Large Bevel Gears - Arnesen Marketing Company · 2010-09-01 · Olper Straße 10–12 · 51491 Overath Germany Text: ... environment and making efficient use of energy. Taking part

The Technical Magazineof the Gearing Partners Klingelnberg and Liebherr

No. 19/2010

Shaping

Large Bevel Gears

Efficient Gear Cutting in High-Strength Materials

Breakthrough to a New Dimension

2sigma RepoRt 19/2010

sigma REPoRT No. 19

Publisher

Sigma Pool

Klingelnberg GmbH Peterstraße 45 · 42499 Hückeswagen Germany

Liebherr-Verzahntechnik GmbH Kaufbeurer Straße 141 · 87437 Kempten Germany

Editorial Staff

Andreas Montag Phone +49 2192 81-370 [email protected]

Editorial Contributions

Dr.-Ing. Christoph Bunsen, Dipl.-Ing. Rudolf Houben, Dipl.-Ing. Stefan Jehle, Dr.-Ing. Andreas Mehr, Dipl.-Ing. Günter Mikoleizig, Dipl.-Ing. Michael Potts, Dr.-Ing. Wilfried Schäfer, Joachim Schuon

Editing and Design

C&G: Strategische Kommunikation GmbH, Olper Straße 10–12 · 51491 Overath Germany www.c-g-gmbh.de

Text: Tobias Hartmann Graphics: Viola Dreyling

Photos

C&G:, Klingelnberg, Liebherr

IMPRINT

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14

Cost Effective Shaping

Blue Competence®


Ready for Large Tasks

Customer Portrait SCHOTTEL-Group

Automatically More Productive


Extending our LeadershipGaining a strong position through Blue Competence®

Dear Readers,

Energy efficiency and conserving resources are important

issues of our time, which have received special attention from

the world’s media in recent years. They are not exactly new

topics, and German industry in particular has been addressing

them successfully for some time. Even if we do not always

manage to attract media attention for our many improve-

ments, large or small, which we achieve, it is in the nature

of our engineers to continue accomplishing more from less.

I would even say that it is one of the core competencies of

German engineering. In the Sigma Pool, both Liebherr and

Klingelnberg have initiated the development of dry cutting of

gears and together with our customers we have successfully

introduced and implemented this process in today’s state of

the art large batch gear production. For example, most bevel

gears today are “dry-cut”, using no oil as lubricant, with

better surface quality and are machined in only 1/3 of the

time. I believe that we very rarely find a better example for

improving productivity and quality and at the same time save

valuable resources. Consequently it is not necessary for there

to be a contradiction between environmental protection and

competitiveness.

The German machine tool sector has already done a great

deal to assume a leading role in respect to energy efficiency.

For example, machines from Liebherr and Klingelnberg are

equipped with maintenance-free direct drives, converting

the energy from braking back into electrical power instead

of wasting it as heat. Additionally, systems are used to switch

off power on idle devices. All this means that our machines

are already energy efficient, despite their high power ratings,

and they are bringing the current trend towards resource

protection to the shop floor right now.

Liebherr and Klingelnberg are by far not the only companies

who have adapted their machines to become more energy effi-

cient. Many other German machine tool builders have already

worked intensively on this issue. Their efforts are apparent in

the Blue Competence® campaign run by the German Machine

Jan Klingelnberg CEO Klingelnberg Group, Board Member of the VDW

Tool Builders’ Association e. V. (VDW). You will find more about

Blue Competence® on Page 9. We – the companies partici-

pating in this campaign – wish to underline the fact that

German machine tool makers are already providing machines

to the global manufacturing environment that combine pro-

ductivity, quality and reliability with a real contribution to

energy efficiency and sustainability. Already today, our ability

to do this significantly sets us apart from our global compe-

tition and gives the user of our equipment a leading edge in

Blue Competence®.

Our commitment to environmental protection and support for

the Blue Competence® campaign is not just a moral obliga-

tion. We believe that accepting the challenge and using our

technological know-how to further improve energy efficiency

and resource protection in our machines will extend our

market leadership and make us better and more successful

companies in the future.

We are conscious of our responsibility for protecting the

environment and making efficient use of energy. Taking part

in Blue Competence® gives us the opportunity not only to do

something beneficial, but to talk about it as well!

I wish you interesting reading.

Yours

Jan Klingelnberg


efficient use of energy in manufacturing – a vital competitive factor. German machine tool manufacturers traditionally rely on energy-saving solutions which reduce resource costs. the outward expression of this philosophy is found in the Blue Competence® framework.

Identifying Potentials – Using Resources Efficiently


“Blue Competence®”

Reduced idling power

Today’s machines are often optimized for the working process

and less attention is paid to the idling process. In order to en-

sure the machine’s temperature stability outside the working

process, idling energy is often not used productively.

High-efficiency ancillary units

In hydraulic systems, for example, 8 Watt valves can be used

instead of the normal 30 Watt valves. It is also possible to use

electric motors with a higher efficiency rating, reducing the

energy employed. Some customers are already using these

ancillary units. Higher investment costs are quickly paid off in

lower energy costs.

Intelligent standby modes

Measurements from the automotive sector show that the

electricity requirement for manufacturing plant in the stand-

by mode, for example during a works assembly meeting, still

amounts to roughly 60 % of the energy used in normal pro-

duction.

Just as in the case of the idling process, there is a conflict

of goals with ideal temperature control of the machine. The

length of time which a break in production will take and the

point at which the machine must again have reached the ideal

process parameters are factors which always need to be taken

into account here.

Condition monitoring

Continuous condition monitoring discovers unused poten-

tials or “power hogs“ in the energy demand of the machine.

Air consumption in production (unscheduled escapes of com-

pressed air) can, for example, have a negative effect on the

energy balance.

Minimization of operating supplies

The energy and resource balance of a machine tool can also

be optimized by minimizing the use of operating supplies. In-

stead of re-lubrication at intervals it is possible to use lifetime

lubrication for bearings. Over-dimensioned cooling systems,

quality problems with filtering and oil carried off with chips

from the process likewise lead to unnecessary use of operat-

ing supplies.➔

The manufacturing companies increasingly factor energy effi-

ciency into their processes. Rising energy prices influence the

cost-effectiveness of production – the focal point is their core

element, the machine tool. This is the starting point for cur-

rent efforts to identify and release the efficiency potentials

which – despite all previous optimization – are still slumber-

ing in the system.

The electric motors in the machine tool are the chief devour-

ers of electrical current. They power the main spindles, pro-

vide hydraulic pressure and move cooling lubricant and chips

through the system. In reality, however, the situation is much

more complex: there are potentials for optimization at the

most diverse points.

If one looks holistically at the energy requirements of a machine

or at its energy saving potential, the following main areas of

relevance appear:

process optimization•

need-based drive power•

reduced idling power•

high-efficiency ancillary units•

intelligent standby modes•

condition monitoring•

minimization of operating supplies •

Process optimization

The task is to optimize machine tools in such a way that their

consumption of resources is minimized. Because idling power

constitutes a large proportion of total energy consumption,

it is advantageous to machine workpieces as rapidly as possi-

ble, so that if there is a shortage of parts the – most efficient

possible – standby mode is activated. Liebherr provides the

plant user with measuring and visualization tools to optimize

sequences in this respect.

Need-based drive power

Many of today’s machine tools are overpowered. This is due

partly to the demand for flexibility – the machines should be

designed for larger future applications – and partly to a kind

of “arms race” aimed at having the highest drive power in the

market. The power actually used for the application is often sig-

nificantly less than the potential provided by the machine.



Example from practice: hydraulic shaping machines

Liebherr hydraulic shaping machines illustrate the potential

improvements in energy efficiency which can be released by

systematic changes in design and process technology.

Hydraulic shaping machines are employed in the manufac-

turing of large module gears, which for geometrical reasons

cannot be produced using rotating tools – for example inter-

nal gears. If especially large forces are needed to manufacture

these gears, the machines work on hydraulic rather than

mechanical principles (see Fig. 1).

The piston principle of a hydraulic shaping machine functions

as follows: a shaping tool is linked to a piston rod. This piston

rod is hydraulically operated from both sides – it is either it-

self the piston or it is operated by a cylinder-piston system.

Hydraulic pressure is now used to move the tool down (usu-

ally shaping motion) and up (reverse stroke – the process may

also partly include “drawing”).

The oil pressure and oil mass, or more precisely the oil mass

flow, are now fixed as a function of the geometry and tech-

nology parameters and controlled via a servo-valve. The

geometry parameters include the position and length of the

gear being machined, the technology parameters include

among other variables the cutting speed and chip thick-

ness.

During the shaping process, the following requirements

arise, starting at the top dead center: the piston must be-

gin its movement with maximum acceleration so that it has

reached the technologically desirable cutting speed before

entering the workpiece. It must then provide the chip remov-

ing force at a speed as constant as possible. The piston rod is

decelerated in as short a time as possible, so that it does not

collide with the geometry of the workpiece when it leaves

the gear. Once the cut is finished, the tool exits, and comes

to a standstill within a few millimetres. It is now retuned as

quickly as possible to the starting point (reverse stroke). This

stroke must take place as rapidly as possible – it has a sig-

nificant influence on the total machining time. The software

and metrology control the individual process steps and mon-

itor them in a closed loop.

In order to guard against all eventualities, the hydraulic

sub-assembly produces at least the pressure and mass flow

required to operate the above process steps reliably, and is

Fig. 1: Internal gear on a hydraulic shaping machine



Load Sensing“If a continuously displaceable directional valve is to achieve a through-flow independent of load pressure and hence capable of providing sensitive speed control for the load, the pressure dif-ferential across the directional valve must be kept constant. Inno-vative systems of this kind, which apart from providing sensitive control also reduce losses, are characterized as “load-sensing”. Load-sensing systems are fitted either with a fixed displacement pump and a pressure compensator or, to save more energy, with a combined pressure/through-flow control system”.

(from Gerhard Bauer: Ölhydraulik. Grundlagen, Bauelemente, Anwendungen, 9th edition 2009)

dimensioned accordingly. The servo-valve blows the product

of generated pressure and mass flow which is not needed by

the process back into the tank.

Specific measures to optimize efficiency

There was an important starting point here: might the assem-

bly be oversized, not with regard to the maximum power itself,

but with respect to the ratio of constantly available maximum

power to the power required in the process?

Together with the Institute for Fluid Power Drives and Con-

trols of the RWTH Aachen (IFAS), the Liebherr development

team performed measurements and tests. While a machine

was being commissioned for a customer, a technically demand-

ing shaping process was observed and the pressures and mass

flows were measured at various locations (e.g. servo-valve

inflow and outflow). Relatively poor process efficiency became

apparent: the power maintained was substantially greater than

actually required. A principle well known in hydraulics, but not

yet exploited in the hydraulic shaping machine, provided a rem-

edy in the form of load-sensing (see info box).

The change in design was based on calculations by IFAS.

Simulation software determined the energy requirement for

the individual steps in various shaping processes with varying

external loads. These measurements were also used to verify

simulation of the corresponding operating point. ➔



The energy flow diagrams (Fig. 2) indicate the enormous po-

tential for savings by this process. In the concrete example,

the energy input is reduced by 28 % for the same effective

useful power.

In order to profit from theses improvements, the new machine

must be fitted with a variable displacement pump and

additional measuring devices.

To this is added the appropriate software to ensure that the

process takes place reliably and in the usual quality under all

conditions. Now that the new system with load-sensing has

been proved in practice, it can be retro-fitted to existing

machines, replacing the former hydraulic system.

The example of hydraulic shaping machines shows that it is

worth looking even at mature systems – there is always some-

thing to improve. ■

Joachim Schuon

Head of Control Development and Electrical DesignLiebherr-Verzahntechnik GmbH Kempten

[email protected]

Dr.-Ing. Christoph Bunsen

Head of Design and Development Liebherr-Verzahntechnik GmbH Kempten

[email protected]

M

otor

pro

cess

80

% e

ffici

ency

Pu

mp

70%

effi

cien

cy

Shap

ing

hydr

aulic

s Pump input power14,450 W

Electric motor power loss3,612 W

Pump power loss4,414 W

Hydraulic power10,036 W

Storage 472 W

Effective power2,088 W

Flow controller1,000 W

Cylinder friction (forward and reverse stroke)449 W

Valve losses 6,344 W Losses in safety valve and yoke 104 W

Power loss· RSV in tank line 186 W· Tank line 180 W

Power loss· RSV in inflow 123 W· Feed lines 82 W· High-pressure filter 37 W

Pu

mp

70%

effi

cien

cy

Shap

ing

hydr

aulic

s

Pump input power10,387 W

Electric motor power loss2,597 W

Pump power loss3,116 W

Hydraulic power7,271 W

Effective power2,083 W

Flow controller548 W

Cylinder friction (forward and reverse stroke)450 W

Valve losses 3,141 WLosses in safety valve and yoke 211 W

Power loss· RSV in tank line 255 W· Tank line 307 W

Power loss· RSV in inflow 0 W· Feed lines 239 W· High-pressure filter 108 W

M

otor

pro

cess

80

% e

ffici

ency

Proc

ess F

orce

15

kN

BEFo

RE10

0 %72

%

AFTE

R

Fig. 2: Energy flows of a shaping machine with hydraulic main drive (example of an energy flow diagram for 26 mm plunge depth)

Proc

ess F

orce

15

kN



Energy-efficient solutions are something German machine

tool manufacturers have been providing for a long time. With

their campaign on Blue Competence® – Taking the initiative

on energy and environment – they are also actively putting

this across to the outside world.

Numerous different measures improve the use of resources

in machine tools. In recent years, for example, more energy-

efficient components have been fitted to machines, together

with closed systems for recycling surplus energy. Added to

this are demand-related energy use and process planning

aimed at global system optimizetion.

These improvements mark out German suppliers in contrast

with their international competitors. They have a clear market

advantage in relation to Asian suppliers, for example, who

are only now beginning to utilise feedback-capable drive and

inverter technology in their machines.

One aim of the Blue Competence® campaign will be to make

the technology benefits of German machine tools clear to

customers, and systematically stimulate demand.

But Blue Competence® is not just market driven. Efficient use

of resources is something legislators are equally concerned

with. As part of an EuP directive, the European Commission

plans to lay down what is needed for an energy-saving

machine tool. At the beginning of this year, it commissioned

preparatory studies looking into mandatory requirements in

this sphere. For its part, industry has already been working

with the EU commission for some time on a voluntary self-

regulation concept, including realistic steps to improve prod-

uct efficiency.

As part of this voluntary commitment, the approach fol-

lowed by the German Machine Tool Builders’ Association e.V.

(VDW) has been to systematise technical and organisational

measures and assess their efficiency potentials. In this pro-

cess, the VDW is providing the chair and secretariat for a new

ISO working group which will lay down internationally agreed

standards for efficiency measures and ways of rating them.

Blue Competence® represents a pledge by German machine

tool builders that their products will meet the highest

requirements in terms of energy efficiency and will comply

with applicable standards. ■

Taking the initiative on energy and environment

A guest contribution by:

Dr.-Ing. Wilfried SchäferCEO of the German Machine Tool Builders’ Association e.V. (VDW)


Ready for Large Tasks


Large Measuring Centers

In manufacturing, precise measurements are the cornerstone

for complying with very tight tolerances and ensuring the

efficiency of the entire operation. Large measuring centers

have to be fast and easy to operate in order to determine the

current quality of the workpiece and decide on any necessary

corrections in the process chain.

The inner life of gear trains for wind turbines is especially

quality-sensitive. These include cylindrical gears, cylindrical

Where large powers and high torque are required, large gears are the answer: in marine drives, cement and coal mills, wind turbines and hydroelectric power plant. to provide a sustainable guarantee of high standards with respect to running properties, efficiency and low noise emissions, test facilities must assure quality and design in the manufacturing process. Klingelnberg has completely redeveloped its range of large industrial measuring centers and adapted them for current market needs.

gear shafts, rings with internal gearings and planetary gears.

Safe, reliable operation – even in heavy weather conditions

– is absolutely essential, as the only way to safeguard a long

and economic operating lifetime.

The increasing size of parts is leading to ever greater chal-

lenges for production quality. Customers or classification

societies need complete documentation, and this can be

assured only by regular measurement and testing. The high ➔



The rotary table and the linear axis measuring attachment are

supported on a load-bearing machine bed. Combined with a

suitable foundation, this provides a geometrically reliable base

for the measuring machine. The machine design enables inspec-

tion of various diameters and distances on the the same work-

piece in one set-up. The gear measuring centers are optionally

available with a straight horizontal measuring axis, including

a 3D stylus system or a downward angled measuring arm.

The horizontal axis is useful in versatile applications for disc-

shaped workpieces and shafts and for gear-cutting tools. The

angled variant is particularly suited for testing gears in planetary

systems used in the wind power sector. Here the task of mea-

surement is to test internal gears with large gear widths and

to perform high-precision dimension, dimensional (MFL)

measurements in workpiece bores. The angled measuring arm

can move the 3D stylus head inside the bore close to the mea-

suring point, ensuring high measuring accuracy.

Special features are used to facilitate loading prior to a mea-

surement. Shaft-type workpieces can optionally be clamped

with a column and tailstock for a fixing range up to 2,500 mm,

so that they can be fixed between centres. Disc-shaped work-

pieces are placed on the rotary table of the measuring machine.

Depending on the size of the workpieces, extra fixtures are

available for this purpose. To make an accurate measurement,

Legend: highlysuitable ••• planned () verysuitable •• notplanned o suitable •

Measurements

P 150–P 350 P 150 W–P 350 W

Cylindrical gear outside teeth ••• ••

Cylindrical gear inside teeth •• •••

Cylindrical gear shafts ••• ••

Bevel gear wheel •• (•••)

Bevel gear pinion shaft ••• (••)

Worm gears ••• (••)

Gear worms ••• (••)

Gear-cutting tools •• o

MFL-shafts ••• ••

MFL-bores • •••

Roughness cylindrical gear ••• (••)

Roughness bevel gear ••• (••)

Grinding burn cylindrical gear (••) (••)

Gear Measuring Centers

Workpiece diameter Workpiece weight

mm kg

P 150 1,800 8,000

P 150 W 1,500 8,000

P 250 2,800 15,000

P 250 W 2,500 15,000

P 350 3,800 20,000

P 350 W 3,500 20,000

requirements for process reliability and the associated quality

documentation call for robust metrology near to the produc-

tion line. Manufacturers of large gears consequently need high-

precision measuring devices which can be operated as easily

as possible.

The new range of models in the P series meet this need.

Klingelnberg now offers continuous measuring technology in

the applications sector up to 3,800 mm. This satisfies maxi-

mum quality requirements and the standards of the classifica-

tion societies. The new machine versions combine demanding

geometry measuring tasks with high-precision gear measure-

ment.

Main goal: shorter floor-to-floor measuring times

Measuring centers for large gears are suitable for measuring

workpieces with an outside diameter up to 3,800 mm and a

weight up to 20,000 kg. The machines have a rotary table and

three linear measuring axes for acquiring measuring data. The

new rotary table provides high running accuracy (radial and

axial runout < 0.5 µm) – important prerequisites for accurate

measurement of size, shape and position deviations during

a single work cycle. A high-precision angle measuring sys-

tem is integrated in the rotary table axis for rotational posi-

tion acquisition. 3D stylus systems with digital data encoders

are used for optimum measured data logging on the tooth

flanks. The traversing paths of the linear axis allow inspection

of up to 800 mm in the horizontal plane and vertical distances

up to 2,000 mm. The rotary table and the linear measuring

axes are powered directly by AC motors for greater guiding

accuracy.



the position of the workpiece axis is

determined in relation to the rotary table

axis. On the P series machines, this can

be done by scanning the reference sur-

face. All measuring movements are then

performed within the workpiece coordi-

nate system.

The control compensates deviations

in a range up to 10 mm. This feature

greatly simplifies loading of the mea-

suring machine, as the operator no

longer has the time consuming task of

aligning the heavy workpieces with the

rotary table axis. Centering elements

together with a mm scale are quite suf-

ficient. As an alternative, the measur-

ing machines can be aligned mechani-

cally via an air bearing integrated in the

rotary table. This can be used to align

even heavy workpieces exactly.

Using the control software, the oper-

ator can quickly create a measuring

program to define the measurement

sequence. He enters the test param-

eters together with the standards or

directives for analysis. The desired and

actual form can then be compared

reliably using the analysis software. This

is important, as large gears with high

profile and tooth trace loads need es-

pecially large modifications. Measuring

times are shortened by programming

fixed measurement sequences, and the

centre performs the prescribed steps

iteratively.

There are various ways of documenting

the results (Fig. 1): apart from print-outs

there is the option of further on-line

processing. The bevel gear closed

loop concept networks the inspection

machine with the other production

units via a database, so that logged

data can be transferred directly to the

gear machining process and the tool

settings.

Versatile adaptability

In addition to the standard equipment, users can opt for additional features

to customize a measuring center. This enables them to respond specifically to

a measuring situation.

Depending on the application, the extra features will substantially reduce

measuring time and provide more flexibility. Special locating and centering ele-

ments aid positioning of disc-shaped workpieces, allowing external or inter-

nal centering. A plastic coating prevents the workpiece from being damaged

during crane loading. The resulting centering accuracy in the millimetre range

is sufficient to start the measuring run immediately. ➔

Fig. 1: Inspection chart: Involute and Lead


Additional mounting tables with different diameters (Fig. 2)

are available for large ring-shaped workpieces. These are

designed to be changed with a short set-up time and effort.

The fixtures used on the rotary table also fit the mounting

tables.

Centers are preferred for fixing shaft-type workpieces. Tail-

stocks in different types are available. Detachable columns

with a tailstock are used for small workpieces or gear-cutting

tools. Fixed columns with tailstock are available for testing ex-

tremely long and large shafts, enabling measurements on up

to 2,500 mm fixing lengths. The column can be moved using

a wireless remote control to adjust the arm for the necessary

fixing length or to adapt it for the loading position.

An optional automatic stylus changer speeds up the process if

a number of different measurements are made in succesion.

The stylus is then changed automatically during the measur-

ing sequence. Precision is maintained due to the high center-

ing accuracy of the stylus holder plate. If the stylus still needs

to be calibrated for certain measurements, this is done outside

the center of the machine. The operator sees the necessary

instructions for a manual stylus change on the screen.

The P series machines also have an optional

feature for measuring surface roughness on the

tooth flanks. The procedure is simple to adapt and func-

tions on the skid plate principle. The parameters it provides

a single run, together with other measurements, are the

centre line average (Ra), the average peak-to-valley height

(Rz) and the maximum peak-to-valley height (Rt). The spe-

cial stylus system is changed either manually or automatically.

Appropriate roughness sensing systems are available for the

respective module sizes.

Precise results can be obtained only if the workpiece tempera-

ture at the time of measurement is taken into account. A differ-

ence of a few degrees Celsius from the reference temperature

(20 °C) will cause results to deviate by two-figure microme-

tre amounts when determining test parameters for profile

tooth traces and for the base tangent length. To avoid such in-

accuracies, the new P machines provide an optional work-

piece temperature sensor. This has to be placed manually on

the workpiece prior to the measuring run. The temperature

measurement takes only a few seconds. All subsequent mea-

surements are then related to the reference temperature.

The angled measuring arm of the W version is fitted with a

monitoring camera. The ultra-compact camera can be fixed

flexibly on the measuring arm according to the intended mea-

surement and the required viewing angle. Its primary task is

to let the operator view the position of the stylus on the

Fig. 2: Mounting table with support and centering element


Dipl.-Ing. Günter Mikoleizig

Head of Design and Development for Gear Testing MachinesKlingelnberg GmbH

[email protected]

monitor of the control unit when measuring inside gear teeth,

and make any necessary corrections.

Feedback from the industry is the basis for developing new

gear testing machines and measuring concepts. The main

focus is on key market requirements for faster processes with

simultaneously high quality standards. The modular design

enables us to customize measuring devices for individual

demand in the industry. ■

Gear measuring center P 150 W Accurate and fast measurements of workpieces upt to 1,500 mm diameter and a weight of up to 8,000 kilograms


Measuring arm with monitoring camera


one-off and small batch production revolves around one central question: how can I automate production with small batch sizes and a big part range cost-effectively?

Automatically More Productive


Pallet Handling System

This leads to further questions: What level of automation do I need to man-

ufacture small batches and a wide range of variant geometries most cost-

effectively? How can I decouple people’s jobs and work times from machine

requirements? Companies with pallet handling systems for manufactur-

ing centers achieve efficient one-off production through increased machine

utilization and extended unmanned operation, coordinated using flexible

control software.

Manufacturing batch sizes of 1 means companies face one central problem

again and again: a low level of automation hampers optimum use of machine

capacity, resulting in comparatively long machining and set-up times and high

unit costs.

Cutting unit costs by 20 %

Raising the level of automation in one-off production cuts wage costs and

boosts machine efficiency. Liebherr’s PHS handling systems tap unused

potentials and cut unit costs by more than 20 %. For workpieces with around

two hours of machining time, costs can be cut by as much as a third. This is

achieved by optimizing machine workloads, reducing manning requirements

and slimming down total investment.

Fixtures are set up in parallel time to primary machining, using separate sta-

tions (Fig. 1) which are available in different variants: for moving, tilting and

turning. Meanwhile the operator can make use of machining running time

for other tasks, meaning that set-up costs are not included in the machine

hourly rate. Flexible fixtures with all-

purpose clamping systems help to keep

down the number of pallets required

(Fig. 2). Multiple reclampings lengthen

machine running times and increase

work inventories in a system. ➔

Fig. 1: Performing set-ups alongside primary machining time takes the pressure off the machine hourly rate

Fig 2: Flexible fixtures with all-purpose clamping systems are the key to a smaller pallet park.

Reduce unit costs by more than 20 %

optimum use of machine capacity•

lower total investment costs•

trouble-free runs with tailor-made software control•

2 machines with pallet changer

1 machine with pallet changer and PHS

unit costs

unit costs

batch batch



Pallet handling systems also cut labor needs by extending un-

manned running times – you can get a third shift and extra

production at weekends.

Lower total investment costs

Wasted productivity due to sub-optimum use of machine

capacity creates a higher ma-

chine requirement – you can

reduce this by improving ca-

pacity utilization to as much

as 90 %. For example, in-

stead of two machines with

a pallet changer, achieving

a capacity utilization of just

75 %, you can use just one

machine with a pallet chang-

er and a PHS pallet handling system – giving you approx-

imately the same number of units. If you need more at a

later stage, you can retrofit the system with extra machining

centers. Extra investment costs are paid off in a comparatively

short time through higher productivity, depending on your in-

dividual plant situation.

optional fixture and materials management

Efficient coordination of resources used for a certain kind of

work or production is a central problem in machine plan-

ning. All too often, unnecessary stops hold up the production

flow. So how can one design and control the use of fixtures

and material so as to save time and costs? System-integrated

fixture and materials management can underpin your

manufacturing environment. Unfinished and finished parts

are stored in the system on europallets, together with the

change over fixture parts. Where necessary these are placed

ready for the operator next to the set-up station. You cut

logistics effort and space requirements significantly.

Consulting identifies individual improvement potentials

In the planning phase, you work jointly with Liebherr to de-

velop a solution which suits your needs. After analyzing cur-

rent status, you choose the system modules you need for your

application. Then, prior to commissioning, Liebherr trains your

personnel in system areas like NC programming and tools,

preparing them for their new tasks.

You need optimization in small series production, too

Due to growing product individualization, small series pro-

duction is playing an increasingly important role by com-

parison with mass production. You have to realize a wider

parts spectrum and various different work processes just as

you do in one-off production – though for a larger number

of units. The task for your company is still to reduce non-

productive times and expand

unmanned or low-manned

operation. Depending on your

needs, the pallet handling

system can also support small-

series production – providing

an extra robot is available to

load the machine. You can

realize this either in an un-

manned operation or along-

side one-off manufacturing, using another machine if one is

available. You get the same significant increases in productiv-

ity as in one-off production.

Workshop operations are still possible

For manual maintenance and testing work, operators can

still access the machining center via the patented front open-

ing (Fig. 3) and use the machines in workshop operations.

This accessibility likewise means that you can load the ma-

chine manually or load heavy parts using an indoor crane – a

significant advantage for automated systems.

“…We know about all the things users

are going to need…”(Stefan Jehle / Liebherr-Verzahntechnik GmbH)

Fig. 3: Simple access via patented front opening



Dipl.-Ing. Stefan Jehle

Product Manager Liebherr-Verzahntechnik GmbH

[email protected]

version sizepallet with workpiece

workpiece diameter

kg mm

PHS 750 PHS 750-L 500 1,000

PHS 750-M 750

PHS 750-H 1,200

PHS 1500 PHS 1500-L 1,500 1,150/1,800

PHS 1500-M 2,000

PHS 1500-H 2,500

PHS 3500 PHS 3500-L 3,500 1,900/2,500

PHS 3500-M 5,000

PHS 3500-H 6,500

Software prevents down times due to missing parts

Cell control is by the modular Soflex PCS system

(Fig. 4), specially developed for controlling manu-

facturing processes. The software keeps process-

es transparent and optimizes your use of capacity

– an important contribution to lean production.

Down times due to missing parts or missing NC

programs are significantly reduced. The ability to

manufacture in line with demand, right down to

lot size one production, benefits companies with

varying production schedules. Tied-up capital is

freed for other tasks by reducing inventories. The

software controls workpiece transport, manages

interim storage, tools and fixtures and provides

NC machining data. It is flexible so that you can

adapt it for individual plant needs: if desired, it

can coordinate additional areas of production not

linked to the pallet handling system, and visual-

ize them clearly on the central control panel. The software

communicates with all common controls and higher-level ERP

systems. “Our background in our own gear manufacturing is

a huge advantage when it comes to design of pallet handling

systems: we know about all the things users are going to

need”, Stefan Jehle, product manager at Liebherr Gear Tech-

nology, points out referring to the company’s knowledge of

the sector. If there are problems during unmanned operation,

the system texts the operator on his mobile phone, so that he

can carry out remote diagnosis or maintenance on line.

Modular building blocks

Liebherr’s PHS pallet handling system comes in three versions,

for workpiece diameters between 1,000 and 2,500 mm and

weights from 500 to 6,500 kg. These different sizes and the

storage system with its modular design mean you can find in-

dividual solutions and add elements as you go along, to give

yourself a tailor-made pallet handling system (Fig. 5). ■

Fig. 4: SOFLEX-PCS-Software visualizes processes clearly and optimizes your use of capacity

Fig. 5


Cost Effective Shaping Efficient Gear Cutting in High-Strength Materials

Gear shaping in high-strength materials is still a largely unresearched area. Liebherr presents state-of-the-art insights emerging from fundamental studies of the topic.


Moreover, there is a lack of fundamental scientifically-based

knowledge needed to design gear shaping processes for mate-

rials of this nature without previous testing, and to realize them

immediately in production. Users and machine tool and tool

manufacturers consequently face very high risks when they

decide to use a manufacturing process of this type.

objectives and procedure

The objective of Liebherr-Verzahntechnik GmbH is to be able

to design a reliable and efficient gear shaping process for

high-strength materials with a tensile strength Rm of 1,100

to 1,400 N/mm² by varying technology parameters and tool

technology, while achieving economic tool lives.

The wear mechanisms in gear shaping of conventional gear

materials (Rm < 1,100 N/mm²) are known, involving, for ex-

ample, crater wear and cutting edge rounding or shifting.

It is not known what types of wear and what wear mecha-

nisms occur during the shaping of high-strength materials.

It is, however, necessary to know this in order to design and

optimize tool technology. The

first step is, therefore, to ac-

quire and characterize the

wear mechanisms on the tool

as a function of the materi-

al and its strength and of the

technology parameters.

It is also important to create

a basis or reference for previ-

ous knowledge from research

or from industrial practice. This

makes it easier to transfer all

the empirical technology and

tool parameter know-how

[6] for a known material, for

example 42CeMo4, to higher-

strength materials. Liebherr has

conducted initial fundamental

studies in close collaboration

with industrial partners. The

resulting insights have already

been integrated into current

production. This report pres-

ents a small selection of uni-

versally applicable results. Our

technology experts will gladly

assist you with further ques-

tions. ➔

Shaping

Starting point and motivation

Alongside the development of new alternative drives, the

trend towards more efficient conventional gears continues

undiminished. One central feature is lightweight and com-

pact gearbox construction, frequently resulting in hard-to-

access machining points like shouldered shafts, inside gears

or outside gears next to collars, where for design reasons

there is only limited scope for tool withdrawal. Gears of this

nature remain the special province of generating gear shap-

ing. Apart from the types of gear already noted (Fig. 1),

another field of applications for generating gear shaping

is the machining of inside gears, where tool withdrawal is

not restricted by a kind of floor. In this area, shaping com-

petes directly with the usually productive broaching process.

The choice between gear shaping and broaching for inside

machining is made on economic grounds and with an eye to

the required workpiece quality.

Machining gears in high-strength and hardened materials

Obtaining the high load capacities which power gear trains

have to achieve increasingly depends on the use of high-

strength or even hardened materials. Research studies into

the machining of hardened steels [2] and the use of broach-

ing [3] and shaping [4, 5] in gearmaking have led to the fol-

lowing conclusions: Machining hardened steels is possible in

principle, but not cost-effective. Process reliability continues to

be very low, so that the use of gear shaping as a hard finishing

process has never become established in industry.

More widespread is the shaping of materials with a tensile

strength Rm of 900 to 1,100 N/mm². The current trend is

towards high-alloyed and high-strength materials with a tensile

strength between 1,100 and 1,400 N/mm². Machining these

materials economically and with high precision is currently one

of the main challenges for gear shaping.

This trend conflicts both with long years of experience by

machine tool, tool and gear manufacturers and with inten-

sive research activity in the field of generating gear shaping –

even today we have no trustworthy principles and know-how

for technology and tool design or knowledge of wear mech-

anisms which could enable us to predict:

achievable gear and surface qualities, •

process stability and•

tool lives.• Fig. 1: Gear making cases which are the special province of gear shaping [1]


Shaping

Results of wear investigations on shaping cutters

Fig. 2 compares the wear on ASP2052 cutters with a TiN coating (top) and

with a (Ti,Al)N coating (center) used to machine an EN-GJS-900-8 with a ten-

sile strength of 900 N/mm² (generally referred to as ADI900). The cutting edge

of one (Ti,Al)N-coated cutter (bottom) was also intentionally rounded. The

design of the cutting data and the geometry of the cutting wedge were iden-

tical on all three cutters. They were tested at constant cutting parameters. All

three cutters were used up to a width of wear land VB of 0.15 mm and the

resulting tool lives were documented (Figures 3 and 4).

As is apparent in Fig. 2, the design of the cutting edge and the choice of coat-

ing both influence the wear behaviour. All three tools exhibit abrasive wear,

but the cutting edge wear resistance is significantly better on the (Ti,Al)N

variant with the rounded cutting edge (bottom). This contributes to a clear

increase in the tool life attained at the same width of wear land.

Influence of tool technology on the tool life

It is already known for other machining processes like turning and milling that

a systematic rounding of the cutting edges will substantially lengthen tool

lives. Tests to date have demonstrated that this also applies to gear shaping.

Fig. 3 shows the tool life diagram for an ASP2052 tool with (Ti,Al)N and a

defined cutting edge rounding used to machine various test materials.

The tensile strength of a 42CrMo4 was varied between Rm = 900 N/mm² and

Rm = 1,000 N/mm². Increasing the tensile strength by 100 N/mm² causes the

WorkpieceModule 3 mm

Pressure angle 20°

Gear width 40 mm

Reference profile DIN861 2

Coating (Ti,AI)N

Cutting edge rounded

Cutting parametersCutting speed 25 m/min

Generating feed 0.3mm/DH

Infeed per cut 2.25 mm

No. of cuts simulated 3

Infeed depth 6.75 mm

Tip chip thickness 0.14 mm

Mean chip thickness 0.09 mm

Fig. 2: Wear behaviour on different shaping cutters

Fig. 3: Tool life diagram – machinability of different materials (ASP 2052 tool material with (Ti,Al)N and cutting edge rounding)

Nu

mb

er o

f cu

ts

Cutting speed (m/min.)

0 10 20 30 40 50 60 70 80 90 100 110 120

350

325

300

275

250

225

200

175

150

125

100

75

50

25

0

42CrMo4V 42CrMo4V2 EN-GJS-900-8 C10

C10


Shaping

Dr.-Ing. Andreas Mehr

Applications technology for grinding and shapingLiebherr-Verzahntechnik GmbH

[email protected]

tool life at a cutting speed vc of 25 m/min to fall considerably.

In a comparison of tool lives, the EN-GJS-900-8 material with

a tensile strength of 900 N/mm² lies between the 42CrMo4

with 900 and that with 1,000 N/mm². This means that the

EN-GJS-900-8 with the same tensile strength of 900 N/mm² is

harder to machine than the 42CrMo4. Fig. 4 below summa-

rizes the achieved tool lives in metres per cutter tooth for the

type of tool concerned under the same test conditions.

outlook and further steps

Together with an industrial partner and Kempten university

of applied sciences, Liebherr has submitted a research ap-

plication on the generating gear shaping of high-strength

materials, in order to acquire further fundamental know-

how. The next tests will focus on the question of how chip

thickness affects the wear behaviour of the cutters and their

tool lives. In addition, machining tests will be performed on

further material variants with tensile strengths exceeding

1,200 N/mm² – all with the central objective of increasing the

future efficiency of generating gear shaping in high-strength

materials. ■

WorkpieceModule 3 mm

Pressure angle 20°

Gear width 40 mm

Reference profile DIN861 2

Cutting parametersCutting speed 25 m/min

Generating feed 0.3mm/DH

Infeed per cut 2.25 mm

No. of cuts simulated 3

Infeed depth 6.75 mm

Tip chip thickness 0.14 mm

Mean chip thickness 0.09 mm

Literature

[1] Verzahntechnik Lorenz GmbH & Co: Verzahnwerkzeuge – Ein Handbuch für Konstruk-tion und Betrieb, 3rd edition, Karlsruhe: G. Braun GmbH, 1977[2] Ackerschott, G.: Grundlagen der Zerspanung einsatzgehärteter Stähle mit geometrisch bestimmter Schneide. RWTH Aachen, doctoral thesis, 1989[3] Klinger, M.: Räumen gehärteter Werkstoffe. RWTH Aachen, doctoral thesis, 1993

Fig. 4: Comparative tool life as a function of tool type

Too

l lif

e (m

/to

oth

)

Tool type

TiN (Ti,AI)N (Ti,AI)N rounded

[4] Peiffer, K.: Wälzstoßen einsatzgehärteter Zylinderräder. RWTH Aachen, doctoral thesis, 1991[5] Vüllers, M.: Hartfeinbearbeitung von Verzahnungen mit beschichteten Hartmetallwerkzeu-gen. RWTH Aachen, doctoral thesis, 1998[6] Doerfel, O.: Optimierung der Zerspantechnik beim Fertigungsverfahren Wälzstoßen. University of Karlsruhe (TH), doctoral thesis, 1998


Rubrik

Large bevel gears can only be used to the optimum if all the steps in their production are interlinked from the very beginning: starting from design through manufacturing and on to assembly inside the gear housing. Klingelnberg’s new large bevel gear manufacturing unit is the core element in the large bevel gear process chain. It is the basis for producing high-quality bevel gear sets, with short delivery times and planning reliability for customers.



Large Bevel Gear Cutting

The high power capacity of large bevel gears is in demand

above all in marine drive technology, in cement and coal dust

mills and in cone crushers. The groundwork for the appli-

cations-oriented design of a bevel gear based on custom-

er’s specifications takes place in the Klingelnberg KIMoS soft-

ware package (Klingelnberg Integrated Manufacturing of

Spiral Bevel Gears), supplemented by the calculational com-

petence of Klingelnberg’s in-house experts. Table 1 overviews

the input variables and results for a basic design. The macro-

geometry is fixed, allowing for the required power transmis-

sion and transmission ratio, combined with the constraints

imposed by the application, such as operational load peaks,

efficiency and noise behaviour. The proof of strength calcula-

tion determines safety factors for root and flank damage us-

ing the methods laid down in the standard, and compares

results with the specified values.

It is increasingly important to take the environment in which

the gear will operate into account back at the design stage.

Manufacturing and assembly tolerances, load-induced deflec-

tions and thermal influences all cause changes in the relative

spatial position of the pinion and wheel during operation. ➔

Input variables for the basic design are:

torque and speed of rotation•

application•

required safety factors for tooth root • and tooth flank

Results of the basic design are:

macro-geometry • (number of teeth, dimensions, …)

load capacity parameters according to DIN/ISO • and other standards

Table 1: Basic design



This is associated with changes in the

contact pattern position and in the back-

lash. The displacement parameters which

appear can be quantified on the basis

of a holistic static and dynamic analysis.

As part of microgeometry optimization,

systematic flank modifications are made

to compensate these displacements and

obtain an optimum load contact pat-

tern. The flank geometry calculated with

KIMoS is used for a tooth contact analy-

sis to visualize the unloaded and loaded

contact pattern positions (Fig. 1), taking

the operating environment into account.

In this way, it is possible to guarantee

a high degree of planning security at a

very early stage of the product develop-

ment process.

From the melt to the blank

Production of the blank is the first step

in the actual manufacturing process.

The material used for large bevel gears

is almost exclusively 18CrNiMo7-6 case

hardening steel. This is characterized by

high attainable case hardening depth

combined with high core hardness. In-

house regulations on purchasing and

delivery with enhanced requirements

in terms of chemical analysis, grain

size, purity and hardenability are used

to supplement DIN EN 10084, entail-

ing melt selection. During hot working

to a rolled or forged blank, it is neces-

sary to guarantee a minimum strain of

4, combined with optimum grain struc-

ture. The blanks are then soft annealed,

tempered and rough turned on all sides.

Documentation of material properties

Large bevel gear process chain

Fig. 1: Tooth contact analysis in KIMoS: load-free, loaded contact patterns and ease-off (top to bottom)

Drive (Optimization of Concave Pinion Flank)

Contact pattern for Mt = 51725 Nm V=0.00mm, H=0.00mm, J=0.00mm

(Gear flank, Drive) 10mm

Max. pressure 1288 MPa

0 MPa 130 Mpa 1300 Mpa

Tip

Root

Toe

Heel

Tester contact pattern for Mt = 1902 Nm V=0.00mm, H=0.00mm, J=0.00mm

(Gear flank, Drive) 10mm

Tip

Root

Toe

Heel

KIMoS*

designdimensioning



Fig. 2: The C 300 gear cutting machine performs the soft gear cutting and subsequent hard gear cutting process

C 300 gear cutting machine

neutral data machine•

cyclo-palloid process using • a monobloc cutter head => twin spindle

dry cutting•

pre-setting and • take-down station

Fig. 3: Cutting tool

SPIRON-U

and required test results, e.g. ultrasonic and magnetic crack

testing, takes place in the form of an approval test certificate

according to EN 10204.

In the main, manufacturing of large bevel gears is accompa-

nied and checked by the classification societies. One main

requirement is clear identification of the feedstock through-

out the process sequence. Particularly during mechanical pro-

cessing for the purpose of producing turned pieces, it is nec-

essary for the sample number and class stamp to be preserved

on the workpiece. This can be ensured by introducing a suit-

able stamping groove early on, in the rolling or forging blank.

Otherwise the workpiece will need to be restamped by an

approving officer during processing.

Efficient gear cutting on large bevel gears

Soft gear cutting takes place on the newly-developed C 300

bevel gear cutting machine (Fig. 2). This CNC-controlled neu-

tral data machine operates on the proven continuous cyclo-

palloid method using a monobloc cutter head. For this pur-

pose, the machine has twin spindles, allowing the pinion to

be machined in a single fixture. The pre-setting station con-

sists of a rotary table fitted with a measuring arm. This is

used to determine the runout deviation of the workpiece

placed on the faceplate. The operator receives the informa-

tion needed to correct the workpiece alignment via a display.

The finished workpiece is placed on the take-down station so

that the workpiece which has been set up simultaneously ➔

blank production green part machining tool setting


Fig. 4:Closed-Loop

DimensionierungDesign

KIMoS


with main process time can in its turn be fed into the machin-

ing position. This guarantees minimized workpiece chang-

ing times.

The SPIRON-U system (Fig. 3, Page 27) is a completely new

tool concept developed for the C 300. It has enabled the dry

cutting process with coated cemented carbide tools, already

established and proven in series production, to be transferred

to the soft machining of large bevel gears. Together with the

elimination of cooling lubricants, it allows to dispense with

cost-intensive tool conditioning through the use of inserts with

four usable cutting edges. The universal tool system is con-

ceived on a modular basis. It consists of cutter head bodies

with nominal radii of 350, 450, 550 and 650 mm. These are

not restricted to one spiral direction, and can be employed

for both soft and hard gear cutting. The universal blades are

classed by their nominal modules (14–46 mm), each covering

a specific normal module range. A nominal module comprises

four blades: inner and outer blades for the left and right spirals

respectively. The high productivity of the SPIRON-U system is

based on consistent realization of a number of starts z0 = 7 by

dispensing with taper and middle tap – former systems work

with three or five blade groups. The proven concept of skiving

with CBN blades was adapted for the larger number of starts

on the cutter head in hard finishing.

Closed Loop

The new generation of CNC-controlled gear cutting machines

has introduced the closed-loop concept to the world of large

dimensioningdesign

KIMoS

heat treatmentmeasurement and any adjustment if necessary

soft gear cutting



bevel gear manufacturing. It ensures that the property profile

of the finished gear always corresponds to the concept with-

in close tolerances. The heart of the closed-loop concept is a

central production database, where the data records devel-

oped with KIMoS are provided for production. All stations,

beginning with the CS 300 tool-setting unit and going on to

the C 300 gear cutting machine and the P 300 gear measur-

ing center, are networked via this central database, and can

work interdependently (Fig. 4)

The CS 300 tool-setting unit reads in the KIMoS data

records from the central database. The cutter head body is

first equipped manually. It possesses radial slots into which

the blades can be fitted smoothly. Apart from measuring

radial and axial runout, the unit also positions the blades

radially in an automated cycle, fixing them from the rear with

the required torque by means of the integrated screwing

unit. The achievable radial runout tolerance is ± 5 µm, and is

finally documented in a test certificate.

All machine setting data required for soft and hard machin-

ing are defined in the KIMoS data record. The section of the

data record necessary in each case is read in by the C 300

bevel gear cutting machine from the central production data-

base. As compared to gear cutting machines of the mechani-

cal generation, this has the following advantages:

Eliminating the laborious manual setting of individual • machine axes from paper setting data means that tool-up times are minimized. At the same time, the machine operator in terms of set-up activities is disburdened.

The individually driven machine axes provide enhanced • degrees of freedom and hence greater flexibility for achieving suitable flank shape modifications.

The P 300 gear measuring center is also integrated in the closed-

loop concept. The nominal data for the pitch and topogra-

phy measurements are read in from the production database.

The actual data of the measurement are also saved in the ➔

CS 300 tool setting unit

testing radial and axial runout•

radial blade positioning•

integrated screwing unit•

P 300 gear measuring center

measurement of pitch and topography•

computer-aided four axis continuous path control•

aligning aids•

tool settingpremachining for hard gear cutting

measurement and any adjustment if necessary


pinion or wheel final machining testing

KIMoS

hard gear cutting C 300


Fig. 5: P 300 test certificate

corresponding data record (Fig. 5). If required, these can

be subjected to a nominal/actual comparison using the

KOMET software. After selecting suitable parameters the

resulting correction data can be transferred via the database

to the gear cutting machine.

In practice, a separate data record is made for each customer

job, to carry out the machining and measuring process

correctly and avoid mix-up. This also assures full documenta-

tion of all relevant process steps.

Heat treatment and hard finishing

Heat treatment in the form of case hardening is absolutely

essential to ensure that the material can meet the demands

and stresses imposed on gear components. This is the only

way to create the graded properties profile: a hard and wear-

resistant surface combined with a tough core. Heat treat-

ment is a core competence for bevel gear manufacturing. The

capacities of the in-house hardening shop were therefore

expanded alongside construction of the new large bevel gear

production facility, and adapted to match the spectrum of

manufactured products.

Heat treatment necessarily entails hardening distortions,

whose minimization is a constant priority. The process chain

was therefore extended to include measurement of distor-

tions on the components. This step directly follows mechan-

ical processing, in the scope of which the reference surfaces

for gear cutting on the pinion and wheel bodies are

machined. On the basis of measured results, data records

required for hardskiving are adjusted individually. The object

is to achieve minimum flank removal, in order to assure a

maximum remaining case hardening depth on the workpiece,

allowing for the required flank modifications. Short process

times are also ensured.

The wheels are first hard machined and measured. After ad-

justment, the same is done to the pinion. This is followed

by final mechanical processing of the wheel body or pinion

shafts and finishing of the bearing seats. Final inspection ends

the process chain.

Documented quality – ready to use

Certification as required is provided to document that the

customer’s specifications and the requirements of the classifi-

cation societies have been fulfilled:

inspection certificate for the material•

contact pattern photographs•

test certificates•

heat treatment certificate (relating to the case • hardening depth achieved)

documentation of mechanical properties•

Each gear set is subjected to a final contact pattern test after

hard gear cutting, in which contact patterns determined un-

der a small test load have to match the prescribed values


final inspection


Dipl.-Ing. Rudolf Houben

Head of Calculation and Design Bevel Gear DivisionKlingelnberg GmbH

[email protected]

Klingelnberg’s New Large Bevel Gear Cutting Line

The new manufacturing location in Hückeswagen

Adding two C 300 machines to the • production area: manufacturing bevel gears up to 3,000 mm diameter

Klingelnberg’s definition of large bevel • gears: diameter 1,100 to 3,000 mm; module 16.5 to 50

simultaneous expansion of existing • capacities in the heat treatment plant

heat treatment of bevel gears up to • 3,000 mm diameter according to the requirements of all classification societies

measuring and test machines up to • 3,000 mm also available

Guidelines for the new production facility

reduce delivery times•

close the process chain•

increase productivity•

optimize set-up times•

reduce idle times in the • process chain

reduce quality costs•

*KIMoS accompanies the entire process chain, provides data for the individual machining steps and makes appropriate updates.

from the KIMoS tooth contact analysis. Provided assumptions made during

dimensioning in relation to displacement values during operation are main-

tained, the contact pattern tests made under load at the customer’s works

should also correspond with the simulated load contact patterns. In certain

cases, a practical certification allows the customer to operate a bevel gear set

of given geometry at a higher power.

Closing the loop

Numerous steps of machining, calculation and documentation lie between

the initial design and the finished and assembled gear set. Two criteria are

crucial along this path:

At the end of the path, the central quality requirements for a bevel • gear have been fulfilled: sustainable load capacity, minimal losses and low noise emissions.

The manufacturing process has been fully documented and is lean – • ensuring the shortest possible process times.

By combining high performance calculation tools with a process- and applica-

tion-optimized machine park, Klingelnberg provides the entire manufacturing

spectrum for large bevel gears from a single source. ■

On the High Seas

Storm-force winds, high waves and extreme temperatures – to reach their goal at sea, offshore supply vessels have to stay maneuverable, even under the hardest conditions. this is an environment that tests men and materials to the limit. the SCHotteL-Group manufactures marine propulsion systems for ships like these, and the bevel gears used in these drives have to meet special demands in terms of operating lifetimes and safety.



SCHoTTEL-Group


SCHoTTEL-Group

Combi Drive (SCD) In the Combi-Drive, the electric motor is integrated vertically in the supporting tube for the rudderpropeller. This arrangement of the electric motor makes the concept comparable to a rudderpropeller with vertical power input (L-system). As neither an upper gear unit nor a cardan shaft is required, the unit remains extremely compact, and from the point of view of the shipyard it is very simple to install in the ship, saving a great deal of space.

Wind force 9. The captain of the supply ship Bourbon Mistral

maneuvers to dock safely with an offshore platform. Powered

by two SCHOTTEL Combi-Drive (SCD) rudderpropellers, the

ship delivers up to 2,700 t of supplies to its destination.

Ships and platforms in the offshore sector are not just ex-

posed to very high stresses. The reliability requirements are

also immense. Any damage would entail downtimes, result-

ing in enormous costs. Shipbuilders and suppliers bear a high

responsibility for the safety of people, the environment and

investments.

As a supplier for the shipping industry and manufacturer of

marine propulsion units, the SCHOTTEL-Group produces a

central component in the complex overall system of the ship.

The 360°-rotatable SCD 2020 propeller units each have a

diameter of 2,650 mm and transmit a power of 2,700 kW –

enough to guide the 4,720 t deadweight plus payload of the

roughly 90 m long Bourbon Mistral precisely to its objective.

Future-oriented technology

A diesel-electric drive, for which the SCD is designed, propels

the supply ship efficiently through the seas. This type of drive

combines mechanical and electrical elements. Intelligent and

efficient power management ensures high efficiency in diesel-

electric ships. This future-oriented technology is increasingly

popular in the marine sector – particularly because of its high

energy efficiency.

Unlike a conventional diesel solution, a diesel-electric con-

cept no longer needs intermediate shafts to transmit power

from the engine. All that is required is cabling to feed current

to the electric motor. This space-saving concept creates

additional loading space in the stern. The flush-mounted

asynchronous electric motor is integrated vertically in the in-

hull supporting tube for the rudderpropeller. The mechanical

gear unit is located in the underwater pod. Power is trans-

mitted from the vertical to the horizontal via a spiral bevel

gear set.

Michael Potts is the technology team leader for SCHOTTEL in

Wismar on the Baltic coast. He points out the significance of

reliable gears. “The most important components in rudder-

propellers are the angular gears, which transmit power via

bevel gear sets. Spiral bevel gears are used, because of the

very high torques that have to be transmitted. Klingelnberg

cyclo-palloid gears are characterized by constant whole depth

of teeth and an epicycloid tooth lengthwise profile. The high

contact ratio on this type of gear, combined with their good

noise behaviour, create optimum conditions for our appli-

cation”.

High precision gears

The gear sets used in the SCD drives are manufactured using

the HPG process. In this gear cutting operation, after rough-

ing and case hardening, the pinions and wheels are finished

using CBN tools developed specially by Klingelnberg. This

results in gear sets with high surface quality and precision.

Manufacturing complies with load capacity and classification

society standards. The HPG gears

used by SCHOTTEL for

offshore applications

achieve quality grade

4 or better

RubrikSCHoTTEL-Group

(according to DIN

3965). The

optimum mate-

rial for this kind

of application is

18CrNiMo7-6

steel, which

Klingelnberg

employs as a

standard in bevel gear

production.

Drive manufacturers

take special care to

ensure that the drive

housings are very

stiffly designed. The

bevel gear sets have to be

safeguarded against the excessive loads

and associated displacements which can

occur under extreme conditions.

Ready for extreme conditions

The Bourbon Mistral has successfully

completed its mission. Thanks to the

perfect mesh of the captain's craftmanship,

his skilled crew and reliable technology.

This combination equips the ship for even

the toughest conditions. ➔


Klingelnberg bevel gear in assembly


SCHoTTEL-Group

Cooperation between the SCHoTTEL-Group and Klingelnberg is not confined to offshore applications. Bevel gears from Hückeswagen are also used in so-lutions for the company’s other target markets. In this interview with Sigma Report, Michael Potts, the SCHoTTEL team leader at its location in Wismar, talk-ed about working with Klingelnberg, about SCHoTTEL products and about their field of applications.

Sigma Report: Mr Potts, can you give us an overview of the

range of products which SCHOTTEL offers. What solutions do

you provide in the marine propulsion sector? What are their

main features?

Michael Potts: Our original core product is the SCHOTTEL

rudderpropeller, SRP for short. Then grouped round the SRP

we have other products

we’ve brought on to the

market throughout decades

of company development: the Twin Propeller, Transverse

Thrusters, the Pump-Jet, the Controllable-Pitch Propeller and

the SCHOTTEL Combi-Drive.

Sigma Report: Aside from the offshore segment, what other

applications are your propulsion units operating in?

Michael Potts: Our units are used in tugs, ferries, river craft,

cruise liners, yachts, specialized tankers and military craft.

Sigma Report: How do you go about designing and devel-

oping the bevel gear sets? Can you give us an idea how you

work with Klingelnberg?

Michael Potts: As suppliers for shipyards, we initially receive

a series of design specifications for the drives, including the

Michael Potts runs through the SCHOTTEL group’s products and their fields of application. The core product is the rudderpropeller


SCHoTTEL-Group

Dipl.-Ing. Michael Potts

Group Manager Technology WismarSCHOTTEL GmbH

[email protected]

Twin-PropellerA continuous propeller shaft, on which the bevel gear is mounted, powers two propellers rotating in the same direction. One advantage is that a smaller diameter is required. This technology is used especially in classic ferries.

Transverse ThrustersThis type of unit is mounted in the bow sections of ships and ensures that they can be maneuverd precisely up to the quay. In terms of bevel gears, the structure is the same as that of the rudderpropeller.

Controllable-Pitch PropellersThese propulsion units are especially suitable for container ships, where high maneuver- ability is of only secondary importance. The controllable pitch propellers have a long propeller shaft with hub. They transmit powers up to 30 MW, and unlike rudderpropellers cannot be rotated and are not 360° steerable.

Pump-JetShallow draught vessels benefit from this type of drive, for example the M boats used by the German Defence Force. Water is sucked in and the flow accelerated before being ejected as a jet at the stern, creating the thrust. The pump-jet is also 360° steerable.

bevel gears. What power is required? What kind of engines

are already there? What is the situation we have to install the

drives in, and how much space is available? What’s also im-

portant is where the ship will be used and its applications

profile. Is it an ice-going offshore supply ship, for example, or

a harbour tug in the Mediterranean? These ship parameters

effect into dimensioning of the bevel gear unit.

For the design itself we define data like the mean normal

module, the number of teeth, the contact stresses, the displace-

ment and the installation space. These data are the basis for

making the drawings and they are transferred to Klingelnberg’s

developers specified as macro- and micro-geometries.

Based on the gear sets which Klingelnberg makes accord-

ing to these data, which the classification societies evaluate

on the spot, SCHOTTEL carries out a load test. Based on the

contact pattern of the prototype, we can then go ahead with

production.

Sigma Report: What role does the feedback you get from

the Klingelnberg development department play?

Michael Potts: We naturally make our specifications as ex-

act as possible, but obviously we also rely on the competence

of our partners – after all, they are the experts where bevel

gears are concerned. In the many years we’ve been working

together we’ve developed a good working relationship, and

built up confidence on both sides.

Sigma Report: Mr Potts, thank you very much for talking

to us. ■


SCHoTTEL-Group

SCHoTTEL-Group

The German SCHOTTEL group is one of the world’s leading

manufacturers of high quality marine propulsion systems. It

develops and produces all-round steerable drive and maneu-

vering systems and complete propulsion systems with powers

up to 30 MW for vessels of all types and sizes.

For more than fifty years, shipbuilders and shipowners have

placed their faith in SCHOTTEL propulsion units. The company

supplies both standard drives and tailor-made solutions.

Since it was founded in 1921, the company’s main focus has

been on introducing technical innovations to the market,

making it an important player in the world of shipbuild-

ing. Its propulsion systems power ships of all types and sizes

reliably and cost-effectively. In addition to supplying propul-

sion and manoeuvring systems, SCHOTTEL staff are on call to

assist clients with intensive advice and service. Local presence,

expert on-site know-how and comprehensive service are

fundamental principles of the company philosophy.

Propulsion systems are manufactured at three locations, Spay

on the Rhine and Wismar in Germany as well as Suzhou in

China, using the latest machines and planttechnology.

SCHoTTEL milestones

1921 Josef Becker (1897–1973) founds his craft enterprise in an old barn

1934 Purchase of the present company site and naming as the SCHOTTEL yard

1958 Founding of the first foreign subsidiary in the Netherlands

1986 Delivery of the largest rudderpropeller, with a power of 6,000 kW

1999 Takeover of WPM Wismar Propeller- und Maschinenbau GmbH and creation of a subsidiary, SCHOTTEL-Antriebstechnik GmbH, located in Wismar

2005 Josef Becker posthumously receives the Elmer A. Sperry Award for his invention of the rudderpropeller, making a substantial contribution to improving worldwide transportation

2008 Expansion of production capacity in the factories at Spay, Wismar and Suzhou

2010 Founding of the SCHOTTEL Academy and the Josef Becker research center

Michael Potts explains how the rudderpropeller (SRP) works. This patented all-round steerable marine drive is based on two angular gears, which transmit the torque from two horizontal drive shafts in the hull via a vertical layshaft to the horizontal drive shaft of the propeller; a principle also known as the Z-drive.


Klingelnberg GmbHPeterstraße 45

D-42499 HückeswagenFon +49 2192 81-0

Fax +49 2192 [email protected]

Klingelnberg AGTurbinenstraße 17CH-8023 Zürich

Fon +41 44 2787979Fax +41 44 2731556

[email protected]

Liebherr-Verzahntechnik GmbHKaufbeurer Straße 141

D-87437 KemptenFon +49 831 786-0

Fax +49 831 [email protected]

www.liebherr.com

www.sigma-pool.com

Large Bevel Gears - Arnesen Marketing Company · 2010-09-01 · Olper Straße 10–12 · 51491 Overath Germany Text: ... environment and making efficient use of energy. Taking part

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