DESIGN OF I.C ENGINE CAM SHAFT Acamshaftis a shaft to which
acamis fastened or of which a cam forms an integral part. Camshafts
are responsible for the accurately-timed fuel injections required
by internal combustion engines. Camshafts have multiple cams on
them, which are used to open valves through either direct contact
or pushrods. A camshaft is directly coupled to the crankshaft, so
that the valve openings are timed accordingly. Then with the use of
CREO three-dimensional model of the cam shaft is obtained. Once the
CAD model is obtained, the part is analyzed using SOLID WORKS
simulation tool by applying chilled iron material and the loads are
applied. The materials used in the camshaft depend upon the quality
and type of engine being manufactured. For most mass-produced
automobiles, chilledcast ironis used. This material is a good
choice for high volume production. A chilled iron camshaft has a
resistance against wear because the camshaft lobes have been
chilled, generally making them harder. When making chilled iron
castings, other elements are added to the iron before casting to
make the material more suitable for its application.
INTRODUCTIONCAM:A projection on a rotating part in machinery,
designed to make sliding contact with another part while rotating
and to impart reciprocal or variable motion to it.Cams are used to
convert rotary motion into reciprocating motion
CAMSHAFT:A shaft with one or more cams attached to it, e.g.
working of valves in an internal combustion engine is controlled by
camshaft. Cam shaft is called the brain of the engine.
CAM TERMINOLOGY
Base Circle:The smallest circle centered on the cam rotation
axis, and tangent to the cam surface.The size of the base circle is
dictated by spatial restrictions of the application.
Trace point:A theoretical point on the follower, corresponding
to the point of a fictitious knife-edge follower. It is used to
generate the pitch curve. In the case of a roller follower, the
trace point is at the center of the roller.
Home Position:The orientation of the cam that corresponds to 0on
a displacement curve.
Reference Circle (or prime circle):A circle centered at the cam
axis whose radius is equal to the distance to the trace point.It is
the smallest circle from the cam center through the pitch curve
Pressure Angle:The angle between the direction of motion of the
follower and the direction of thecamcontact forceis called pressure
angle.Pressure angle should not exceed 30.Pitch curve: The path
generated by the trace point at the follower is rotated about a
stationary cam.Working curve: The working surface of a cam in
contact with the follower. For the knife-edge follower of the plate
cam, the pitch curve and the working curves coincide. In a close or
grooved cam there is an inner profile and an outer working
curve.
CAM SHAPE
1. PLATE CAMORDISC CAM:The follower moves in a plane
perpendicular to the axis of rotation of the camshaft. A
translating or a swing arm follower must be constrained to maintain
contact with the cam profile. 2. GROOVED CAMorclosed cam:This is a
plate cam with the follower riding in a groove in the face of the
cam.
Grooved cam
1. CYLINDRICAL CAMOR BARREL CAMThe roller follower operates in a
groove cut on the periphery of a cylinder. The follower may
translate or oscillate. If the cylindrical surface is replaced by a
conical one, a conical cam results 2. END CAM This cam has a
rotating portion of a cylinder. The follower translates or
oscillates, whereas the cam usually rotates. The end cam is rarely
used because of the cost and the difficulty in cutting its
contour.
Cylindrical cam and End cam
MOTIONOF THE CAM
When the cam turns through one motion cycle, the follower
executes a series of events consisting of rises, dwells and
returns.Riseis the motion of the follower away from the cam
center,dwellis the motion during which the follower is at rest;
andreturnis the motion of the follower toward the cam center.
Lift:Lobe lift is the distance the lifter moves in one
directionLobe lift is the difference in measurement between the
nose of the lobe and the base circle of the lobeValve lift is what
most people are taking about when they refer to lift and is simply
lobe lift multiplied by the rocker arm ratio
MATERIALS USED IN CAMSHAFT:
Camshaft material is the most important detail in stopping
premature wear of performance camshafts.There are various materials
that camshafts are manufactured from:-
CAST IRONS
1. HARDENABLE IRON:This is Grade 17 cast iron with an addition
of 1% chrome to create 5 to 7% free carbide.After casting, the
material is flame/or induction hardened, to give a Rockwell
hardness of 52 to 56 on the C Scale. It is not the most suitable
material for performance camshafts in overhead cam (OHC)
engines.
2.SPHEROIDAL GRAPHITE CAST IRON KNOWN AS SG IRON:
A material giving similar characteristics to hardenable. Its
failing as a camshaft material is hardness in its cast form, which
tends to scuff bearings in adverse conditions. The material will
heat treat to 52 to 58 RockwellC. This material was used by Fiat in
the 1980s
3.CHILLED CHROME CAST IRON:Chilled iron is Grade 17 cast iron
with 1% chrome. When the camshaft is cast in the foundry, machined
steel moulds the shape of the cam lobe are incorporated in the
mould. When the iron is poured, it hardens off very quickly (known
as chilling), causing the cam lobe material to form a matrix of
carbide (this material will cut glass) on the cam lobe. This
material is exceedingly scuff-resistant and is the only material
for producing quantity OHC performance camshafts.
CONCLUSION OF CAST CAMSHAFTS:When purchasing a camshaft, enquire
which material the camshafts are produced from. A chilled iron
camshaft may be more expensive, but its resistance to wear in all
conditions, far exceeds any other type of cast iron.
STEEL CAMSHAFTS
1.CARBON STEEL EN8(BS970 080M40)/EN99(BS970 070M55):Used mainly
in the 1930 to 1945 period and is currently used for induction
hardened camshafts in conjunction with roller cam followers, due to
the through-hardening characteristics of the material.2. ALLOYED
STEELS EN351 AISI 8620 and EN34:Used by British Leyland in the A
Series and B Series engine and best when run against a chilled cam
follower.3.NITRIDING STEEL EN40B:The best steel for camshafts. When
nitrided it gives a surface hardness and finish similar to chilled
iron.We used this when replacing chilled iron camshafts in
competition engines. This material is used on several of the
current F1 engines.
CONCLUSIONIn general, steel is a good camshaft material.
However, the type of steel has to be matched with the cam follower
it runs against, as different grades of steel have different scuff
characteristics.
DESIGN PROCEDURE:
Profile Design according to requirement:Design a cam for
operating the exhaust valve of an oil engine. It is required to
give equal uniform acceleration and retardation during opening and
closing of the valve each of which corresponds to 69 of cam
rotation. The valve must remain in the fully open position for 20
of cam rotation.
The lift of the valve is 37.5 mm and the least radius of the cam
is 40 mm. The follower is provided with a roller of radius of 20 mm
and its line of stroke passes through the axis of the cam.
Proposed Profile Design:ConstructionFirst of all, the
displacement diagram, as shown in Fig 1, is drawn as discussed in
the following steps:
1.Draw a horizontal line ASTP such that AS represents the
angular displacement of the cam during opening ( i.e out stroke) of
the valve (equal to 60), to some suitable scale. The line ST
represents the dwell period of 20 i.e the period during which the
valve remains fully open and TP represents the angular displacement
during closing (i.e return stroke) of the valve which is equal to
60.
fig. 1
1.Divide AS and TP into any number of equal even parts (say
six).2.Draw vertical lines through points 0, 1, 2,3 etc. and equal
to lift of the valve i.e 37.5 mm.3.Divide the vertical lines 3f and
3f into six equal parts as shown by the points a, b, c. .. and a, b
, c in figure 1.4.Since the valve moves with equal uniform
acceleration and retardation, therefore the displacement diagram
for opening and closing of a valve consists of double
parabola.5.Complete the displacement diagram as shown in Fig. 1
Fig- 2
Now the profile of the cam, with a roller follower when its line
of stroke passes through the axis of cam as shown in Fig 2
METHODS OF MANUFACTURING:
1.CASTING: Chilled cast iron is primarily used for production of
cam shaft. The development of automobile industry and engine power
brings up more advance requirement for properties of camshaft. In
casting process, there are more chances of casting defects such as
shrinkage defect, porosity, crack, insufficient pouring. However
for higher loads in roller contact, cast camshafts with induction
hardened cam lobes can be used.
2.FORGING: Forged or manufactured from a steel bar camshafts are
also used for certain high loaded diesel engines. These are
produced on computer-controlled forging systems with integrated
heat treatment or machined from steel bar.
3.MACHINING:Machining is necessary for giving final dimension to
the cam.
A.While using Casted or Forged CAM only Final Machining is
require to achieve final size within the required tolerances. In
this process casted or forged CAM are in the required shape but
their size is maintained by machining and finishing operation.
B.While Using Metal Billet (metal rod), the profile of cam is
obtained by removing excess material which from metal billet. In
this process only machining is required to manufacture CAM.
A detailed description of the processes for mass manufacturing
is as follows:
1.TURNING & DRILLING:The raw forging is put in this machine
and center drilling and turning on one side is done here.
2.TURNING: Here the turning of the 6 journals takes place. There
are 4 tools used for this turning Rough, Neutral, Left and Right
tool. Also, Grooving and Parting operation is performed on the left
side of the shaft.
3.DRILLING:This machine drills the diameter 4.5 dowel hole which
is used as reference for further operations.
4.GRINDING JOURNALS:Here grinding and finish grinding of the 6
journals takes place. Carborundum wheels are used for grinding.
5.GRINDING ON FACE: An angular grinding wheel is used for the
face grinding operation. At this stage, inspection is done after
every 10 components using gauges.
6.DRILL DOVEL HOLE:Grinding of the Cam is done here. The dowel
hole is taken as the reference.
7.LAPPING:To give superfinish in microns, lapping is done using
lapping paper on the Cams.
8.SLITTING:This machine makes a slit in the right side of the
shaft to fit in the engine. The cutter used is a Saw cutter and
pneumatic deburring is done here.
9.AIR & WATER CLEANING:This is the Washing Machine where
water and air jets are used to clean the component of dust, oil,
chips etc.
10.INSPECTION:This is a Measuring Machine used to check for
tolerances - Runouts and Diameters of journals ( all 6 and center
4). The machine then declares the component as OK, NG, or BAD.
INTRODUCTION TO CAD
Computer-aided design (CAD), also known as computer-aided design
and drafting (CADD), is the use of computer technology for the
process of design and design-documentation. Computer Aided Drafting
describes the process of drafting with a computer. CADD software,
or environments, provides the user with input-tools for the purpose
of streamlining design processes; drafting, documentation, and
manufacturing processes. CADD output is often in the form of
electronic files for print or machining operations. The development
of CADD-based software is in direct correlation with the processes
it seeks to economize; industry-based software (construction,
manufacturing, etc.) typically uses vector-based (linear)
environments whereas graphic-based software utilizes raster-based
(pixilated) environments.CADD environments often involve more than
just shapes. As in the manual drafting of technical and engineering
drawings, the output of CAD must convey information, such as
materials, processes, dimensions, and tolerances, according to
application-specific conventions.CAD may be used to design curves
and figures in two-dimensional (2D) space; or curves, surfaces, and
solids in three-dimensional (3D) objects. CAD is an important
industrial art extensively used in many applications, including
automotive, shipbuilding, and aerospace industries, industrial and
architectural design, prosthetics, and many more. CAD is also
widely used to produce computer animation for special effects in
movies, advertising and technical manuals. The modern ubiquity and
power of computers means that even perfume bottles and shampoo
dispensers are designed using techniques unheard of by engineers of
the 1960s. Because of its enormous economic importance, CAD has
been a major driving force for research in computational geometry,
computer graphics (both hardware and software), and discrete
differential geometry. The design of geometric models for object
shapes, in particular, is often called computer-aided geometric
design (CAGD).Current computer-aided design software packages range
from 2D vector-based drafting systems to 3D solid and surface
modellers. Modern CAD packages can also frequently allow rotations
in three dimensions, allowing viewing of a designed object from any
desired angle, even from the inside looking out. Some CAD software
is capable of dynamic mathematic modeling, in which case it may be
marketed as CADD computer-aided design and drafting.CAD is used in
the design of tools and machinery and in the drafting and design of
all types of buildings, from small residential types (houses) to
the largest commercial and industrial structures (hospitals and
factories). CAD is mainly used for detailed engineering of 3D
models and/or 2D drawings of physical components, but it is also
used throughout the engineering process from conceptual design and
layout of products, through strength and dynamic analysis of
assemblies to definition of manufacturing methods of components. It
can also be used to design objects. CAD has become an especially
important technology within the scope of computer-aided
technologies, with benefits such as lower product development costs
and a greatly shortened design cycle. CAD enables designers to lay
out and develop work on screen, print it out and save it for future
editing, saving time on their drawings.Types of CAD Software2D
CADTwo-dimensional, or 2D, CAD is used to create flat drawings of
products and structures. Objects created in 2D CAD are made up of
lines, circles, ovals, slots and curves. 2D CAD programs usually
include a library of geometric images; the ability to create Bezier
curves, splines and polylines; the ability to define hatching
patterns; and the ability to provide a bill of materials
generation. 3D CADThree-dimensional (3D) CAD programs come in a
wide variety of types, intended for different applications and
levels of detail. Overall, 3D CAD programs create a realistic model
of what the design object will look like, allowing designers to
solve potential problems earlier and with lower production costs.
Some 3D CAD programs include Autodesk Inventor, Co Create Solid
Designer, Pro/Engineer Solid Edge, Solid Works, Unigraphics NX and
VX CAD, CATIA V5.
3D Wireframe and Surface ModelingCAD programs that feature 3D
wireframe and surface modeling create a skeleton-like inner
structure of the object being modeled. A surface is added on later.
These types of CAD models are difficult to translate into other
software and are therefore rarely used anymore. Solid ModelingSolid
modeling in general is useful because the program is often able to
calculate the dimensions of the object it is creating. Many
sub-types of this exist. Constructive Solid Geometry (CSG) CAD uses
the same basic logic as 2D CAD, that is, it uses prepared solid
geometric objects to create an object. However, these types of CAD
software often cannot be adjusted once they are created.
INTRODUCTION:CREO1. CAD Computer aided design (cad) is defined
as any activity that involves the effective use of the computer to
create, modify, analyze, or document an engineering design. CAD is
most commonly associated with the use of an interactive computer
graphics system, referred to as cad system. The term CAD/CAM system
is also used if it supports manufacturing as well as design
applications. 2. Introduction to CREOCREO is a suite of programs
that are used in the design, analysis, and manufacturing of a
virtually unlimited range of product. In CREO we will be dealing
only with the major front end module used for pan and assembly
design and model creation, and production of engineering drawings
Schamtickoo(4) . There are wide ranges of additional modules
available to handle tasks ranging from sheet metal operations,
piping layout mold design, wiring harness design, NC machining and
other operations. In a nutshell, CREO is a parametric,
feature-based solid modeling system, Feature based means that you
can create part and assembly by defining feature like extrusions,
sweep, cuts, holes, slots, rounds, and so on, instead of specifying
low-level geometry like lines, arcs, and circle& features are
specifying by setting values and attributes of element such as
reference planes or surfaces direction of creation, pattern
parameters, shape, dimensions and others. Parametric means that the
physical shape of the part or assembly is driven by the values
assigned to the attributes (primarily dimensions) of its features.
Parametric may define or modify a features dimensions or other
attributes at any time. For example, if your design intent is such
that a hole is centered on a block, you can relate the dimensional
location of the hole to the block dimensions using a numerical
formula; if the block dimensions change, the centered hole position
will be recomputed automatically. Solid Modeling means that the
computer model to create it able to contain all the information
that a real solid object would have. The most useful thing about
the solid modeling is that it is impossible to create a computer
model that is ambiguous or physically non-realizable.PTC was
founded in 1985, by Samuel Peisakhovich Ginsberg, who previously
worked at Prime Computer, Computer vision (CV) and Applicon.
Pro/ENGINEER (a.k.a. Pro/E), the company's first product, shipped
in 1988. John Deere became PTCs first customer. Once an initial
version of Pro/ENGINEER was developed, the company received venture
capital funding from Charles River Associates and Steve Walske
became the CEO. Pro/ENGINEER was the first commercially successful
parametric feature based solid modeler. Through a combination of
innovative technology, and no-holds-barred sales tactics, PTC
quickly became a major force in the CAD industry. Its strong ascent
continued unabated until the mid-1990s, when the introduction of
Microsoft Windows NT, and the availability of commercial geometric
modeling libraries opened the door to a new generation of low-cost
competitors and PTC's reputation for overly aggressive sales
tactics alienated many of its customers. These competitors,
symbolized by Solid works, squeezed PTC from the bottom, while more
established companies like Uni graphics and IBM held the 'high
ground' in automotive and aerospace industries. PTC's sales began a
multi-year decline from which it took years to recover. It took a
new CAD product and an expanded product line, but PTC has been able
to transform itself over the past 10 years into the third largest
provider of Product Lifecycle Management software.On December 29,
2006 Standard & Poor's bumped PTC off its S&P 500 Index,
and replaced it instead with the newly spun-off natural gas company
Spectra Energy Corp. (NYSE: SE). Parametric then bumped Pier 1
Imports Inc. (NYSE: PIR), a retailer of home furnishings, down one
spot and off the bottom of the S&P Midcap 400 Index In 2008,
PTC once again achieved revenues of over $1 billion something it
had not been able to accomplish since 1999. Creo Elements/Pro, a
product formerly known as Pro/ENGINEER is a parametric, integrated
3D CAD/CAM/CAE solution created by Parametric Technology
Corporation (PTC). It was the first to market with associative
solid software. The application runs on Microsoft Windows platform,
and provides solid modeling, assembly modeling and drafting, finite
element analysis, and NC and tooling functionality for mechanical
engineers. The Pro/ENGINEER name was changed to Creo Elements/Pro
on October 28, 2010, coinciding with PTCs announcement of Creo, a
new design software application suite. CREO Elements/Pro (formerly
Pro/ENGINEER), PTC's parametric, integrated 3D CAD/CAM/CAE
solution, is used by discrete manufacturers for mechanical
engineering, design and manufacturing.
Companies use Creo Elements/Pro to create a complete 3D digital
model of their products. The models consist of 2D and 3D solid
model data which can also be used downstream in finite element
analysis, rapid prototyping, tooling design, and CNC
manufacturing.
All data is associative and interchangeable between the CAD, CAE
and CAM modules without conversion. A product and its entire bill
of materials (BOM) can be modeled accurately with fully associative
engineering drawings, and revision control information. The
associativity functionality in Creo Elements/Pro enables users to
make changes in the design at any time during the product
development process and automatically update downstream
deliverables. This capability enables concurrent engineering
design, analysis and manufacturing engineers working in parallel
and streamlines product development processes.Almost thirty five
years, Pro Engineer has been the most powerful and popular three
dimensional computer aided design software in the industry. It has
the most variety in terms of advancement in product development
capabilities that are currently available on the market. The
current version of Pro Engineer is simple to use and learn. It is
also very affordable, no matter whether you have small or medium
size company.Basically, it has every functionality that a small
business requires to be successful. There are many client
testimonials that provide product feedback. This is very important
because it is always good to hear it straight from your peers. Many
people who represent the small business sector were recently asked
about why they used this particular CAD software.The testimonials
were located in various countries and represented various
industries, too. They explained how the software provided a
positive impact on their operations and the feedback was quite
comprehensive. Almost everyone has business operations that involve
daily tasks, including product design. Some types of projects and
product design include the creation of an overall design for the
primary components. This is an assembly type that could be assisted
by the Pro Engineer program.Once you have created the digital model
you may need to apply plastics on the form. The software allows you
to create the styling and surfacing as it is able to simulate the
characteristics of different materials. This step will then drive
the design for all the product sub-components. The pro Engineer
software allows you to drive the complete design from a single
primary file. When this product is used, be sure to be aware of the
specifications and references in the very beginning of the
project.If changes need to be made, the software can do it
automatically. Both the measurements and the design of the
components can be altered according to your desire. This creates
very big opportunities for time saving processes, which is why this
software program is such a powerful tool. Without the ability to
make changes so easily, you would have to make drafts for every
component on an individual basis.If for example the complete
dimensions of your design change, some types of software would
force you to change each individual component where asPro Engineer
allows you to change all the units and measurements easily in one
go.It can also be used for production. When three dimensional files
are sent to a manufacturer, they can construct the tooling straight
from the files that were sent. Since the file is 3D and it has all
the necessary measurements, it can save you from the task of
needing to create the two dimensional sketches that the
manufacturer used to have to have in order to review the part.You
can easily make call outs to the important measurements that you
want them to perform total analysis on. This is a real time saver.
In fact, it can save about twenty per cent of the time that you
would generally spend on the whole process.If you need a powerful
solution for your product development process, Pro Engineer is a
good choice, as it allows you to work more efficiently and with
improved design verification.
There are six core CREO concepts. Those are:1. Solid Modeling 1.
Feature Based 1. Parametric 1. Parent / Child Relationships 1.
Associative 1. Model CentricThe display of CREO will be as below1.
Hide the browser by clicking on the arrows at the right of the
screen, as shown in the figure. You should now see the graphics
area where parts will be displayed. 1. Select [File] -> [Set
Working Directory] from the menu bar, and select the folder in
which you downloaded the part. All work you do will be saved to the
folder you set as the working directory. 1. Select [File] ->
[Open] from the menu bar, and select the part you downloaded. 3
Capabilities and Benefits:1. Complete 3D modeling capabilities
enable you to exceed quality arid time to arid time to market
goals.1. Maximum production efficiency through automated generation
of associative C tooling design, assembly instructions, and machine
code.1. Ability to simulate and analysis virtual prototype to
improve production performance and optimized product design.1.
Ability to share digital product data seamlessly among all
appropriate team members1. Compatibility with myriad CAD
tools-including associative data exchange and industry standard
data formats.
4 Features of CREOCREO is a one-stop for any manufacturing
industry. It offers effective feature, incorporated for a wide
variety of purpose. Some of the important features are as
follows:1. Simple and powerful tool1. Parametric design1.
Feature-based approach1. Parent child relationship1. Associative
and model centric4.1. Simple and Powerful Tool CREO tools are used
friendly. Although the execution of any operation using the tool
can create a highly complex model4.2. Parametric Design CREO
designs are parametric. The term parametric means that the design
operations that are captured can be stored as they take place. They
can be used effectively in the future for modifying and editing the
design. These types of modeling help in faster and easier
modifications of design.4.3. Feature-Based Approach Features are
the basic building blocks required to create an object. CREO models
are based on the series of feature. Each feature builds upon the
previous feature, to create the model (only one single feature can
be modified at a time). Each feature may appear simple,
individually, but collectively forms a complex part and assemblies.
The idea behind feature based modeling is that the designer
construct on object, composed of individual feature that describe
the manner in which the geometry supports the object, if its
dimensions change. The first feature is called the base
feature.4.4. Parent Child RelationshipThe parent child relationship
is a powerful way to capture your design intent in a model. This
relationship naturally occurs among features, during the modeling
process. When you create a new feature, the existing feature that
are referenced, become parent to the feature4.5. Associative and
Model CentricCREO drawings are model centric. This means that CREO
models that are represented in assembly or drawings are
associative. If changes are made in one module, these will
automatically get updated in the referenced module.5. CREO Basic
Design ModesWhen a design from conception to completion in
pro/engineer, the design information goes through three basic
design steps.1. Creating the component parts of the design1.
Joining the parts in an assembly that records the relative position
of the parts.1. Creating mechanical drawing based on the
information in the parts and the assembly.6 Assembly in CREO
:Bottom-Up Design (Modeling): The components (parts) are created
first and then added to the assembly file. This technique is
particularly useful when parts already exist from previous designs
and are being re-used.7.Top-Down Design (Modeling): The assembly
file is created first and then the components are created in the
assembly file. The parts are build relative to other components.
Useful in new designsIn practice, the combination of Top-Down and
Bottom-Up approaches is used. As you often use existing parts and
create new parts in order to meet your design needs.Degrees of
Freedom:An object in space has six degrees of freedom.1.
Translation movement along X, Y, and Z axis (three degrees of
freedom)1. Rotation rotate about X, Y, and Z axis (three degrees of
freedom)Assembly Constraints:In order to completely define the
position of one part relative to another, we must constrain all of
the degrees of freedom.Mate, Align, and InsertMateTwo selected
surfaces become co-planar and face in opposite directions. This
constrains 3 degrees of freedom (two rotations and one translation)
Mate OffsetTwo surfaces are made parallel with a specified offset
distance.Align CoincidentTwo selected surfaces become co-planar and
face in the same direction. Can also be applied to revolved
surfaces. This constrains 3 degrees of freedom (two rotations and
one translation). When Align is used on revolved surfaces, they
become coaxial (axes through the centers align).
Align OffsetThis can be applied to planar surfaces only;
surfaces are made parallel with a specified offset distance.Align
OrientTwo planar surfaces are made parallel, not necessarily
co-planar, and face the same direction (similar to Align Offset
except without the specified distance).InsertThis constrain can
only be applied to two revolved surfaces in order to make them
coaxial (coincident). Fundamentals of assembly in CREO :In pull
down menu File, select new and then choose Assembly option.
Adding Components:In the pull-down menu, select Insert
>Component>AssembleOr pick the Add Component button in the
right toolbar.Browse and open the file for the first component.
CREO Modules Sketcher (2D) Part (3D) Assembly Drawing and Drafting
Sheet Metal Rendering
Features of CREO engineering:Pro/engineering is a one-stop for
any manufacturing industry. It offers effective feature,
incorporated for a wide variety of purpose. Some of the important
features are as follows: Simple and powerful tool Parametric design
Feature-based approach Parent child relationship Associative and
model centricSimple and Powerful Tool CREO tools are used friendly.
Although the execution of any operation using the tool can create a
highly complex model Parametric Design CREO designs are parametric.
The term parametric means that the design operations that are
captured can be stored as they take place. They can be used
effectively in the future for modifying and editing the design.
These types of modeling help in faster and easier modifications of
design.Feature-Based Approach Features are the basic building
blocks required to create an object. CREO engineering wildfire
models are based on the series of feature. Each feature builds upon
the previous feature, to create the model (only one single feature
can be modified at a time). Each feature may appear simple,
individually, but collectively forms a complex part and assemblies.
The idea behind feature based modeling is that the designer
construct on object, composed of individual feature that describe
the manner in which the geometry supports the object, if its
dimensions change. The first feature is called the base
feature.
Parent Child RelationshipThe parent child relationship is a
powerful way to capture your design intent in a model. This
relationship naturally occurs among features, during the modeling
process. When you create a new feature, the existing feature that
are referenced, become parent to the feature.
Associative and Model CentricPro/Engineering wildfire drawings
are model centric. This means that Pro/Engineering models that are
represented in assembly or drawings are associative. If changes are
made in one module, these will automatically get updated in the
referenced module.CREO Basic Design Modes When a design from
conception to completion in pro/engineer, the design information
goes through three basic design steps.Creating the component parts
of the designJoining the parts in an assembly that records the
relative position of the parts.Creating mechanical drawing based on
the information in the parts and the assembly.
CREO consider these steps as separate modes, each with its own
characteristics, files extensions, and relation with the other
model. As you build a design model it is important to remember that
a information, dimensions, tolerances, and relational formulas are
passed from model to the next bi directional. This means that if
you change your design at any model level. CREO reflect it all
model levels automatically.If it is planned ahead and the use
associative features correctly, you can save significant time in
the design and engineering change order process. Assembly in
CREO:Bottom-Up Design (Modeling): The components (parts) are
created first and then added to the assembly file. This technique
is particularly useful when parts already exist from previous
designs and are being re-used.Top-Down Design (Modeling):The
assembly file is created first and then the components are created
in the assembly file. The parts are build relative to other
components. Useful in new designsIn practice, the combination of
Top-Down and Bottom-Up approaches is used. As you often use
existing parts and create new parts in order to meet your design
needs.Degrees of Freedom:An object in space has six degrees of
freedom. Translation movement along X, Y, and Z axis (three degrees
of freedom) Rotation rotate about X, Y, and Z axis (three degrees
of freedom)Assembly Constraints:In order to completely define the
position of one part relative to another, we must constrain all of
the degrees of freedom. Mate, Align, and Insert MateTwo selected
surfaces become co-planar and face in opposite directions. This
constrains 3 degrees of freedom (two rotations and one translation)
Mate OffsetTwo surfaces are made parallel with a specified offset
distance.Align CoincidentTwo selected surfaces become co-planar and
face in the same direction. Can also be applied to revolved
surfaces. This constrains 3 degrees of freedom (two rotations and
one translation). When Align is used on revolved surfaces, they
become coaxial (axes through the centers align).Align OffsetThis
can be applied to planar surfaces only; surfaces are made parallel
with a specified offset distance.Align OrientTwo planar surfaces
are made parallel, not necessarily co-planar, and face the same
direction (similar to Align Offset except without the specified
distance).InsertThis constrain can only be applied to two revolved
surfaces in order to make them coaxial (coincident).Steps for
modeling of cam shaft in creo:A}Extrude material:
Solid Extrude1. Select the front plane and click at extrude
icon. It will get you into the sketching window.2. Using a circle
tool make a simple circle of your desired diameter (just for
practicing) and click at ok button.
Now the creo parametric will show you the preview of your
extrude. You can change the depth of extrude by moving the white
square. To do this just click and hold at the white square and move
your mouse to change the length.
Two types of extrude depth we can learn at this moment. Blind
SymmetricBlind option is shown in above figure and it is by default
active. To use symmetric option click at extrude depth tool menu
and select the symmetric option you will see that extrude become
equally distributed with reference to sketching plane.
IntroductionAn extrude feature is based on a two-dimensional
sketch. It linearly extrudes a sketch perpendicular to the
sketching plane to create or remove material. You can either select
the sketch first or then start the Extrude tool, or you can start
the Extrude tool and then select the sketch.In this exercise we
will try to learn about Solid Extrude Extrude cut/Add Extrude
Thicken Cut/Add Tapper
Also we will use extrude types such as Blind Symmetric Through
all Through until To selected
Here is the dashboard option used in extrude tool. I label it to
show you the function of the representative option.Solid:this
option is selected by default to make solid extrude.Surface:This
can be used to extrude the sketch as surface.Extrude depth tool: is
used to control extrude by specifying some constraints.Depth
value:used to specify the dimension of depth. Some extrude types do
not need this.Invert tool:used to change the direction of extrude
opposite to the reference direction.Remove material:this tool is
used to remove the material while extruding.Thicken tool:is used to
extrude as thick sheet. Thickness value can be adjust by entering
the value in box (just right to the thicken tool). The invert tool
next to the thicken tool is used to specify the direction of
thickness by three ways.1. One side2. Both sides: thickness will be
symmetric to the sketch boundary.3. Other side
When we click at the extrude depth tool a drop down menu will
open in which you can see the following icons representing the
specific conditions for extrude.one thing you should note that
these option will be available when you will try to make extrude on
existing surface or model.1) Blind:this is the default option. In
simple words the depth is blind for program and we have to provide
it.2)Symmetric:This option provides you the equal extrude on the
both side of sketching plane.3)To next:using this option you can
stop extrude to very next surface that extrude encountered. Depth
dimension is not required for this option4)Through All:This option
will generate extrude that through to the whole model. Depth
dimension is not required.5)Through until:This option will cause
extrude to stop at the specified/selected surface and section must
pass through the selected surface.6)To selected:it is just like the
through until option except that sectiondoes nothave to pass
through the selected surface.
Insert plane parallel to extrude serfaceExtrude with the shape
of cam profile as shown
Make liner pattern of above extruded feature