1 1) Company Profile- TAL Mfg Solutions is the subsidiary of TATA Enterprises. The company merged out from TATA group in the year 2000. 1.1) About TAL TAL is India’s premier manufacturing solutions provider to the automotive and auto-ancillary industry; It is a wholly owned subsidiary of Tata Motors, India's largest automobile company. Tracing its origins to the mid 1960’s, TAL was formed by the merger of the resources of the Machine Tool and Growth Divisions of the Tata Motors – Pune facility in March, 2000. A business unit structure brings in focused competencies in design and manufacture of a wide range of precision machine tools, equipment and unit material handling systems for automotive industries and fluid power solutions for the tipper truck markets, from its current facility in Pune, India. This focus coupled with successful and innovative solutions have been responsible for its rapid growth (6-year CAGR: 26% approx.). TAL has design, NPD and manufacturing facilities at Pune and is setting up a new factory to cater to Aerospace requirements and its expansion plans at Nagpur, India TAL Manufacturing Solutions is a company focused on offering cost-effective and total solutions in the field of manufacturing engineering. A pioneer in its area of expertise, TAL'S international-standard technology and its talented team of professionals make it a premier player in the machine tools and equipment-building industry. TAL has designed, built and installed thousands of machine tools for the production shops of Tata enterprises, automobile and other divisions, and it has been responsible for putting up the manufacturing facilities of the TATA Enterprise. PDF created with pdfFactory Pro trial version www.pdffactory.com
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1
1) Company Profile-
TAL Mfg Solutions is the subsidiary of TATA Enterprises. The company merged out from TATA group in the year 2000.
1.1) About TAL
TAL is India’s premier manufacturing solutions provider to the automotive and
auto-ancillary industry; It is a wholly owned subsidiary of Tata Motors, India's largest
automobile company. Tracing its origins to the mid 1960’s, TAL was formed by the
merger of the resources of the Machine Tool and Growth Divisions of the Tata
Motors – Pune facility in March, 2000. A business unit structure brings in focused
competencies in design and manufacture of a wide range of precision machine tools,
equipment and unit material handling systems for automotive industries and fluid
power solutions for the tipper truck markets, from its current facility in Pune, India.
This focus coupled with successful and innovative solutions have been responsible
for its rapid growth (6-year CAGR: 26% approx.). TAL has design, NPD and
manufacturing facilities at Pune and is setting up a new factory to cater to Aerospace
requirements and its expansion plans at Nagpur, India
TAL Manufacturing Solutions is a company focused on offering cost-effective
and total solutions in the field of manufacturing engineering. A pioneer in its area of
expertise, TAL'S international-standard technology and its talented team of
professionals make it a premier player in the machine tools and equipment-building
industry.
TAL has designed, built and installed thousands of machine tools for the
production shops of Tata enterprises, automobile and other divisions, and it has
been responsible for putting up the manufacturing facilities of the TATA Enterprise.
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As seen in the layout TAL has one of the best equipped shops which include almost all types machines as listed below.
• WALDRICH COBURG’ Plano Machining Centre, PMC 2500 AT-M2 • DIXI' 510 5-Axis CNC Horizontal Jig Boring Machine
• SIP' 6A & 7A Vertical Jig Boring Machines
• MAS' WKV 100 Jig Boring Machines
• 'WALDRICH COBURG' Slide way Grinding Machines
• FORTUNA' Cylindrical Fine Grinding Machine
• STUDER' Cylindrical Fine Grinding Machine
• WOTAN' Internal Grinding Machines
• REISHAUER' Gear Grinding Machines
• A fully equipped Fabrication Shop, Heat Treatment facilities
1.8.)IT’S PRODUCTS ARE:-
Their main products are CNC’S with horizontal and vertical machining centre’s (HMC’s and VMC’s resp.), Special purpose machines like gear shaping, counter boring machines.
They also provide fixtures for various other companies. Their CNC machines are as shown below:-
Fig. V400(VMC) Fig. V500 PLUS (VMC)
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To reduce the weight of existing spindle housing casting without compromising the strength and to modify it to eliminate its drawbacks for reducing manufacturing cost
2.2 SCOPE OF PROJECT:-
1. Study of various components (along with spindle housing) and their sub-assemblies of VMC machine.
2. Identification of the item for weight reduction & improvement in design. 3. Study of component & its assembly interface & existing design features. 4. Listing requirements of design features that are required for design of spindle
housing. 5. Collection of technical data and literature survey. 6. Solid Modeling and FE analysis of existing spindle housing. 7. Concept design of spindle housing with different shape & ribbing structures for
strengthening. 8. Finalization of concept for max. strength to weight ratio with the help of FE analysis. 9. Detailed design & modeling of new spindle housing taking in to account design
considerations & functional features for improved design.
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Weight reduction is one of the important criteria for any product. While designing a component its strength to weight ratio, manufacturing process, assembly process, serviceability, etc are considered to keep cost of product minimum.
For the objective of cost reduction, it was decided to reduce the weight of major casting components of all VMC’s. Each of its casted components (base, column, top piece, saddle, spindle housing) were distributed among us. I was given the spindle housing for weight reduction for one of the VMCs named V400 low weight.
With reference to existing spindle housing weight was to be reduced without compromising the strength. Required improved design features also to be added in new spindle housing eliminating the drawbacks listed below:-
1. Unwanted cutouts on outer face of ribs which increased machining cost. 2. Entire outer face of was considered while machining and all outer dimensions were
needed to be controlled. 3. Manufacturing and assembling cost of spindle housing cover was more. 4. Weight was more. 5. Spindle cooling arrangement was not proper. 6. Fumes entered the spindle motor from bottom.
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Designing of a component involves determining the kinematic arrangement, force analysis, selection of materials and proportioning of geometry which may be controlled by one or all of following: strength, rigidity, critical speed, appearance, fabrication and foundry practice.
Design of a component must involve a plan as shown:-
Fig.4.1.1 Factors involved in design of a component
4.2 METHODOLOGY FOR DESIGN & DEVELOPMENT OF NEW PRODUCTS:
Methodology for designing & developing of new product can be applied for tooling, also. Product development is the process of creating a new product to be sold by a business or enterprise to its customers.
In the document title, Design refers to those activities involved in creating the styling, look and feel of the product, deciding on the product's mechanical architecture, selecting materials and processes, and engineering the various components necessary to make the product work.
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Development refers collectively to the entire process of identifying a market opportunity, creating a product to appeal to the identified market, and finally, testing, modifying and refining the product until it is ready for production.
The process of developing new products varies between companies, and even between products within the same company. Regardless of organizational differences, a good new product is the result a methodical development effort with well-defined product specifications and project goals.
Table 4.1 Design and development methodology for new products.
Concept
Development
System-Level
Design
Detail
Design Manufacturing
Testing and
Refinement
Production
Ramp-Up
Study feasibility
of product
concepts.
Develop
industrial
design concepts
Build and test.
Experimental
prototypes
Generate
alternative
Architectures.
Define systems
and interfaces
Refine industrial
design.
Define part
geometry Spec
Materials Spec
Tolerances
Industrial design
control
documentation
Estimate
manufacturing
cost.
Identify suppliers
Make/buy study
Define final
assembly
scheme
Reliability,
Performance
and life tests.
Get regulatory
approvals.
Implement
design changes
Evaluate
early
production
output
4.3 STRENGTH AND RIGIDITY OF MACHINE FRAMES (RIBBING PATTERNS):-
4.3.1 Requirements of a machine frames: The frames and their components are the load carrying and supporting bodies of machine tools. They are required to support and guide the individual constructional and functional elements; their size and shape is determined by particular functions of the machine. Their form is basically dependent upon the position and length of the moving axes and upon the consequential arrangement of the components and sub-assemblies (e.g. works spindles, slides, supports, drives, motors, control units). In addition, they are influenced by the
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magnitude of the process forces and accessibility for their own construction, as well as their use and operation.
The masses of the moving components of the machine and the work, as well as the machining forces, must cause only minimal distortions of the machine
4.3.2 Structural design consideration: During the operation of the machine fool, a majority of its structures are subjected to compound loading & their resultant deformation consists of torsion, bending & tension or compression under simple tensile or compressive loading. The strength and stiffness of an element depend only upon the area of cross-section. However, the deformation and stresses in elements subjected to torsion and bending depend, additionally, upon the shape of cross sectional areas. A certain volume of metal can be distributed in different ways to give different values of the moment of inertia and sectional modules. The shape that provides the maximum moment of inertia and sectional modulus will be considered best, as it will ensure minimum values of stresses and deformation. Box type of section was the highest torsional stiffness & in the overall assessment seems best suited both in terms of strength and stiffness. All considerations combined, point towards the overwhelming superiority of box type profile over others for machine tool structure. Bending and torsional resistance of differing cross-sections are shown in figure 4. and 4.10.
Figure 4.9 Bending resistance of differing cross sections
Figure 4.10 Torsion resistance of differing cross sections
Ribbing : Various rib designs for columns are shown in figure 4.11. Bending and torsional
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All these structural design considerations are taken in to account while designing of structural frames for fixtures. 4.4 WHAT IS A SPINDLE? Spindles are rotating drive shafts that serve as axes for cutting tools or hold cutting instruments in machine tools. Spindles are essential in machine tools and in manufacturing because they are used to make both parts and the tools that make parts, which in turn strongly influence production rates and parts quality. The design of the spindle and the quality of the components inside the spindle are major factors that contribute to the spindle's durability and longevity. The spindle should be designed in such a manner so that features that keep chips and coolant are kept out of the spindle's bearing system, like in an air purge system and wipers that use positive lubrication pressure to protect the spindle from contaminants.
Fig. A Typical Spindle Housing
4.5 STUDY OF SPINDLE HOUSING: The housing is a part and parcel of the spindle. The shaft of the spindle and the motor required to run the spindle must be held in a housing, which we refer to as spindle housing.
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The spindle housing is available in various styles and sizes and may be an integral part of the machine tool. The spindle housing is connected to the machine tool by using a flange or attaching bracket.
4.5.1 Materials used in making spindle housing
• Cast Iron • Iron • Stainless steel • Cast aluminum • Brass etc.
4.5.2 Functions of spindle housing The primary functions of a spindle housing are as follows:
• To locate the bearings: High precision bearings, which run at dN values, must be located exactly in terms of size, geometry etc.
• To provide the lubrication required by the spindle. • The housing also provides air seal, cooling water or oil, and other utilities required by
the spindle. If the spindle uses oil lubrication, then the spindle housing includes drilled passages to transfer the oil or oil mist to each bearing, and then again transfer the oil out of the bearing to a return line.
• The spindle housing provides a cooling liquid: This helps in removing heat produced by the spindle motor stator, as this heat would affect the spindle performance as a complete unit.
4.5.3 TYPES OF SPINDLE HOUSING There are various types of spindle housing and depending on the different housing, different mounting types are there for spindles. They are as follows: 1.Cartridge spindle housing This is a popular type of housing used in spindles. This type of housing is the simplest to service, and the tolerances required for high speed are very easy to obtain when the housing of the spindle can be produced as a cylinder. The cylindrical cartridge-style spindle is clamped around the housing with a split-clamp mounting block. Advantages Advantages of this type of mount are as follows:
The split-clamp mounting allows the use of standard off-the-shelf cartridge spindle designs.
• It permits easy axial and rotational adjustments of the spindle housing inside the mounting bracket.
• Once the mounting block has been located, cartridge-style spindles can be removed and re-installed without requiring adjustments of positions.
• The spindle is easy to remove from the mount.
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• This type of split-clamp mounting block usually occupies more space than a block-style spindle housing design or flange mount design.
• Increased chances for spindle bearing failure. • Possible variations in axial location and orientation. • Additional weight imposed on the machine structure.
2. Flanged cartridge spindle housing Most spindle builders offer flanged cartridge spindle housings, which allow the spindle to be flange or face mounted. This is usually the preferred method of spindle mounting in a machining center. The flange is a simple, round flange ring having a bolt hole pattern that is permanently attached to the spindle housing. Special designs are possible also with flats or other cut-outs as required to accommodate the machine or tool changer design. Advantages The advantages of this type of mounting are:
• Lower chances for spindle bearing failure • Guaranteed repeatability in X, Y, Z locations and squareness when a spindle is re-
mounted. • Very little extra space required. • Spindle removal is easy. • The flange design provides additional clearance to the spindle nose if the mounting
flange can be located further back on the spindle housing. Disadvantages
• Spindle housing can be more expensive than an off-the-shelf cartridge-style spindle. • Spindle can only be removed and installed one way .
3.Block (box) type spindle housing This type of housing is designed to be lifted and transported using either eye bolts or swivel type hoist rings. Spindles are arranged with tapped holes in the top of the spindle housing for accepting eyebolts and such spindles are manufactured to be lifted from the top. Block style housing has jack screw holes both sides and keyway in housing. With this design, the spindle housing has one or more flat sides, which allows the spindle to be mounted directly onto one of the sides. Advantages The advantages of block type mounting are as follows:
• Lower chances for spindle bearing failure caused by mounting problems.
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• It is possible to design good repeatability in X, Y, Z locations and squareness in such designs when a spindle is re-mounted.
• Very little extra space required.
Disadvantages
• Some spindle mount design may be special, and the spindle is more expensive than a standard cartridge-style spindle.
• If the machine design does not include accurate location of the block housing, it becomes very necessary to position the spindle every time it is re-installed.
4.5.4 PARAMETERS TO CONSIDER FOR SPINDLE HOUSING DESIGN For any type of spindle, the housing design parameters include the following:
• Precision dimensions from base to spindle centerline • Spindle-bearing condition • Spindle operating condition • Assembling tolerance • Cooling condition • Geometric dimension • Maximum strength to weight ratio
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4.6.2. REDESIGN OF SPINDLE BOX WITH POLYMER CONCRETE
The aim of this investigation is the possibilities of use of polymer concrete in building machine tools structures. For that purpose, the NC lathe Mazak QT 10 headstock’s housing is completely redesigned and polymer concrete constructive material has been chosen and applied. The available references have shown same examples of use of polymer concrete in substitution of cast iron in the design of machine tool beds. We have decided to investigate the possibilities of the use of polymer concrete in main spindle housing design due to the more demanding requirements connected with the dissipation of temperature, damping and high accuracy of the structure. To be able to redesign the original housing for the purpose of material substitution, we have performed static, dynamic and thermal analysis of the structure. The differences in the material properties (table 1) have initiated an iterative process of redesign with the aim to achieve properties of the original design. Both models, of original and redesigned housing are shown on figure .
a. Original b. Redesigned
Figure . Models of main spindle housing
4.6.3. THEORETICAL AND EXPERIMENTAL STUDY OF NEW DESIGN
We have performed wide numerical and experimental investigations of static, dynamic and thermal behaviour of original and redesigned housing, part of which are presented in this article
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INTRODUCTION TO FE ANALYSIS:- For generations, a matter of concern to engineers has been the determination of stress and strains in machines and structures. The finite element method will solve problems when the component geometry is complex and cannot be modeled accurately with standard strength of material analysis. In these complex cases, the determination of stresses, strains, deformations and loads favors the finite element method. FEA consists of a computer model of a part that is stressed and analyzed for specific results. It is used in new product design and existing product refinement. In case of structural failure, FEA may be used to help design modifications to meet the new condition.
A Brief History:- Finite Element Analysis (FEA) was first developed in 1943 by R. Courant, who utilized the Ritz method of numerical analysis and minimization of variation calculus to obtain approximate solutions to vibration systems. Shortly thereafter, a paper published in 1956 by M. J. Turner, R. W. Clough, H. C. Martin, and L. J. Topp established a broader definition of numerical analysis. The paper centered on the "stiffness and deflection of complex structures". By the early 70's, FEA was limited to expensive mainframe computers generally owned by the aeronautics, automotive, defense, and nuclear industries. Since the rapid decline in the cost of computers and the phenomenal increase in computing power, FEA has been developed to an incredible precision. Present day supercomputers are now able to produce accurate results for all kinds of parameters. How FE Analysis works (PROCEDURE):-
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MESH FORMATION FINAL STRESS ANALYSIS OUTPUT FEA uses a complex system of points called nodes which make a grid called mesh. This mesh is programmed to contain the material and structural properties which defines how the structure would react to certain loading conditions. Nodes are assigned at a certain density throughout the material depending on the calculated stresses. This mesh acts like a spider web- a mesh between two nodes. Usually included in finite element method of stress analysis are the following steps:-
1. Divide the parts into discrete elements. 2. Define the properties of each element. 3. Assemble the element stiffness matrices (done by the software used). 4. Apply known external loads at nodes. 5. Specify part support condition. 6. Calculate stresses in each element (done by the software used).
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It is made up of high quality grey cast iron with heavy ribbing to provide high stiffness and low weight. It bears all the weight of the machine and thus is the most heavy component.
CROSS SLIDE:-
It is mounted on the base and provides Y-axis linear motion. Motion is done with the help of a driving motor and a ball screw arrangement.
SADDLE:-
It is mounted on LM guides on the cross slide and provides X-axis linear motion. Motion is done with the help of a driving motor and a ball screw arrangement.
TABLE OR TOPPIECE:-
It is mounted on the saddle and carries the work piece. T slots are grooved on it which help to mount the work piece in any position.
COLUMN:-
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Column is mounted on the base. It carries the spindle housing and ATC arrangement. It enables Y-axis linear motion. It is also heavily ribbed as the base to avoid deflection.
AUTOMATIC TOOL CHANGER (ATC):-
It is an arrangement for easy storage and retrieval of cutting tool whenever required. It consists of a disc type magazine, an ATC arm, tool holder and tools. ATC arm helps in exchanging the tool as per program.
BALL SCREW ASSEMBLY OR DRIVE ASSEMBLY:-
It converts rotary motion of motor into linear motion. This assembly is used for X,Y and Z axis movement of tool (spindle housing) or work piece (table).
TELESCOPIC COVER:-
It is mounted on the top surface of saddle (X axis), cross slide(Y axis) and LM guide ways(Z axis). They are stainless steel plates which can slide over each other. They prevent entry of chips, coolant, dust and dirt.
ELECTRICAL CABINET:-
It is a rectangular cabinet which contains all necessary electrical parts like fuses, switches and wiring necessary for running of the VMC. It is mounted on the rear side of machine on the column.
6. STUDY OF ALREADY EXHISTING SPINDLE HOUSING:-
Existing spindle housing is box (block) type. The present housing weighs 280kg and carries a weight of motor and spindle which is 98kg (i.e)100kg. It is made up of grey cast iron type 60 & grade 25 as it provides necessary damping to reduce vibrations generated and therefore helps in maintaining high precision.
6.1 PART PROPERTIES
Part Name Spindle housing V400 m/c
Mass 280 kg
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6.3MODELING AND STUDY OF PRESENT DESIGN FEATURES:-
Model on Solid Edge referring its drawing was necessary to understand its dimensions, shapes, errors and where the shape can be reduced or changed completely.
Model drawing is also necessary to carry out the FE Analysis.
Its model is as shown:-
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1. Holes for motor mounting. (6 nos.) 2. Holes for spindle mounting. (6 nos.) 3. Holes for mounting declamping assembly.(4 nos) 4. Threaded holes for eye bolts used for chain attachment of counter balance.(2 nos.) 5. Holes for lubrication of LM Guides (linear motion guides).(12 nos) 6. Holes for mounting keeper plates. (10 nos.) 7. Holes for nut of ball screw. (6 nos.)
6.4 FE ANALYSIS:- This was followed by its FE analysis on Solid Edge Software to locate its weaker spots and change them accordingly. 6.4.1 LOAD CALCULATIONS:-
For FE Analysis forces applied on the component must be determined. There are two forces acting on this component. They are
1. When doing any operation the component must not fail. So it is necessary to design a component considering the maximum operating force which acts in milling operation. Force calculation is as shown:-
DATA:- Dia. of milling cutter varies from 32mm to 315mm. (TaeguTec manual pg. A 109) Cutter dia. = d = 125mm Minimum number of teeth’s = z = 4 Feed varies from 0.15 to 0.35 Average feed = f = 0.25 Cutting speed = v = 260m/min (TaeguTec pg.A105)
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Depth of cut = ap = 2.5 (TaeguTec pg.A105) Power = P = 9 KW Efficiency = η = 0.6 (varies from 0.5 to 0.75) CALCULATIONS:- Width of cut = L = ¾ D (TaeguTec pg.A107) = ¾ × 125 = 93.75 mm Spindle speed = N = v × 1000 Π × D = 260 × 1000 Π × 125 = 662.08 rpm Feed/min (Table feed) = F = f × z × N (TaeguTec pg.A106) = 662.08mm/min Chip removal rate = Q = L × F × ap (TaeguTec pg.A106) 1000 = 93.75 × 662.08 × 2.5 1000 = 155.175 cm^3/min
Power = P = _Q × Ks_ (TaeguTec pg.A106) 60 × 102 × η Specific cutting force = Ks = P × 60 × 102 × η Q = 9 × 60 × 102 × 0.6 155.175 = 212.972 kg/mm^2
Power = P = Fc × V (M P 2 pg. 1.2) 60 × 102 Cutting force = Fc = P × 60 × 102 V = 9 × 60 × 102 260 = 211.846 kgf (since 1kgf = 10N) = 211.846 × 10
= 2110.846 N
Cutting force of milling cutter is 2110.846 N
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6.4.2 THE FINAL FE ANALYSIS OUTPUT IS AS SHOWN:- Stress limit must be up to 10MPa and deflection limit must be 10 microns (i.e.) 0.01mm for a safe component. FOR STRESS:-
Maximum value of permissible stress is 0.598 MPa
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7.1 INTRODUCTION:- Design problems are usually complex as much as they have several goals, many constraints and even greater number of possible solutions. Design projects should have well defined objectives and constraints, which helps in determining how radically the concepts need to be in fulfilling the requirements. Concept design is considered to be the creative heart of any design process. Concept design generates lot of concepts or ideas then selects the best idea. Good concept design process requires the use of intuition, imagination and logic to come up with creative solution to a well-defined problem. Concept design is the stage of product development that usually demands the greatest creativity. Creativity is required at every stage in the design and development process. The most exciting and challenging design is that which is truly innovative and the creation of radical design variation from anything currently in use. This process of creativity itself has three different stages as shown in figure 4.6
Figure 6 .1 Stages of Creativity Preparation: Preparation for problem solving involves diverging and converging thinking steps. Divergent thinking step is throwing a wide net to catch all possible aspects of the problem and all possible angles of solution. Converging step is to reduce all these possibilities to a single manageable problem definition. This does not mean reducing the problem to a single design
Creativity
Preparation Idea Generation Idea Selection
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with known features or attributes. A problem definition can be quite broad but it needs to have clear goal and boundaries. In this project, the objective is to design assembly fixtures that perform the function of assembling the various parts of steel track and the fixtures are to be manufactured in-house with available resources and technology. Idea generation: Idea generation is the heart of creative thinking. The ideas produced are the lifeblood of any creative process. The initial conceptual development of ideas is the hardest part of any design program. A number of fixture design concepts were developed and these ideas are analyzed for both, technical feasibility and target specification requirements. Idea selection: The role of idea selection is to think of all possible solutions and pick the best. Idea selection aims to identify, the best idea that solves the problem, from among a wide range of ideas created. A great deal of creativity is required in idea selection to mix and match useful elements of different ideas. Idea selection depends on the requirements of product that is to be assembled and analysis of concepts to find out whether or not those requirements are fulfilled by the concept. The Ideas developed are also analysed for their feasibility in different phases as given below. 7.2 RIBBING PATTERNS:-
Various conceptual design modeling, followed by its FE Analysis done using the same forces and parameters which were used in the analysis of existing spindle housing were done. Conceptual design means trying out various ribbon patterns and shapes keeping the stress and deflection under a limit and developing a final component. The maximum permissible stress limit is 10MPa and deflection limit must be up to 10 microns (i.e.) 0.01mm for a safe component. 7.2.1 RIBBING PATTERN -1 Starting with a simple design- a normal cylindrical shape with two attaching ribs. It’s model and FE Analysis is as shown:-
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7.2.2 RIBBING PATTERN-2 Just normal holding rib will never work, therefore a box shape was tried next. It’s model and FE Analysis is as shown:-
7.2.3 RIBBING PATTERN-3 Web design inside the box was necessary as it will have the same effect as that shown above , reducing lot of weight.maximum stresses are seen at the joint between the box and vertical face connecting to the column.
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7.2.4 RIBBING PATTERN-4 Maximum stresses are seen at the joint between the box and vertical face connecting to the column, thus it is to be filled with at the corner. Also middle useless part of the web inside the box was to be cutout.
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This model worked as more stresses are seen only at joining corners, so they needed to be either rounded or chamfered.
The more the edge is curved the lesser stress it has. Thus, decreasing the deflection.
The detailed FE Analysis is shown in next finalization article.
8. FINALIZATION:-
Finalization of this ribbing pattern was done on the basis of the results of the FE analysis performed using the same forces. The displacement value was 7 microns, thus below its limit of 10 microns. Stress value was also within permissible limit, which is 10 Mpa. The output of its final FE Analysis is as shown:
STRESS OUTPUT:
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Maximum value of displacement comes out to be 0.007 mm.
Now finishing of this casted component by chamfering, adding fillets or rounding the edges in the casting stage itself is needed. Improved design features are needed to be added in order to eliminate the drawbacks.
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9. MODELING AND ADDITION OF IMPROVED DESIGN FEATURES
Modeling of new spindle housing includes crosschecking all dimensions and tolerances. Finishing of this casted component by chamfering, adding fillets or rounding the edges in the casting stage itself is needed. This also avoids stress concentration. Improved design features are needed to be added in order to eliminate the drawbacks. These improved design features are listed below followed by a figure showing their respective position:-
1. Mounting pads (10 nos.) Initially cutouts were given on outer face of ribs which increased machining cost. By adding raised pads, machining cost and time would be reduced as only their
faces would be needed to be machined. Also the entire outer face dimensions are not
needed to be controlled for cover mounting. 2. Holes for motor mounting. (4 nos.) 3. Holes for spindle mounting. (6 nos.) 4. Holes for declamping assembly.(4 nos) 5. Threaded holes for eye bolts used for chain attachment of counter balance. (2 nos.) 6. Holes for lubrication of LM Guides (linear motion guides).(12 nos) 7. Holes for mounting keeper plates. (10 nos.) 8. Holes for attaching the bracket holding the cable carrier. (2 nos)
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5. Kenneth B & Michael B, “Engg. Materials”, Prentice-Hall of India, pg 28,29 & 593. 6. Mike Baxter, “Product design-A practical guide to systematic methods of new product
development”, Chapman and Hall. Pg. 61-89. 7. Gokhale, Deshpande, ”Practical FE Analysis”, Finite to Infinity Publications. 8. Donaldson, C.Lecain, G.H. and Gwold V.C., “Tool design”, TATA McGraw Hill