Machine Design Lab-I

7/31/2019 Machine Design Lab-I

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area, weight, volume, centre of gravity and moment of inertia. In FEA the object is

divided into large number of finite elements which form an interconnecting network

network concentared nodes. By using a computer with significant computational

Capabilities, the entire object can be anlysed for stress- strain, heat transfer coefficient

at nodes. By determining the inter relating behaviours of all nodes in the system, the

behaviour of the entire object can be assessed.

Design review & Evaluation:Checking the accuracy of the design can be accomplished conveniently on the graphical

terminal. Semiautomatic dimensioning and tolerance routines which assign size specification to

surface indicated by the user help you to reduce the possibility of dimensioning errors. The

designer can zoom in on part design details and magnify the image on the graphics screen for

close scrutiny. One of the most important evaluation feature available on some computer aided

design systems is KINEMATICS. The available kinematics packages provide the capability to

animate the motion of the simple designed mechanisms such as hinged component & linkages.

Commercial kinematics software available is ADAMS (Automatic Dynamic Analysis ofMechanical Systems).

Automated Drafting:It involves the creation of hard-copy engineering drawings directly from the CAD data base.

Most of the CAD systems are capable of generating as many as six views of the parts.

Engineering drawings can be made into company drafting standard by programming the

standards into the CAD system. Implementation of computer in the design stage becomes the

subset of design process. Once the conceptual design materializes in the designer mind the

geometric model starts by the appropriate CAD software. The choice of geometric model to

CAD is analogous to the choice of a mathematical model to engineering analysis. A valid

geometric model is created by definition translator, which converts the designer input into theproper database format. In order to apply engineering analysis in geometric model, interface

algorithms are provided by the system to extract the required data from the model database to

perform the analysis. In case of FEA, these algorithms from the finite element modeling

package of the system. Design testing & evaluation may require changing the geometric model

before finalizing it. When the final design is achieved the drafting & detailing of the model

starts, followed by documentation & production of final drawings.

Geometric modelling:

A geometric modeling is defined as the complete representation of an object that includes in

both graphical and non-graphical information. In computer-aided design, geometric modelingis concerned with the computer compatible mathematical description of the geometry of an

object. The mathematical description of the geometry of an object to be displayed and

manipulated on a graphics terminal through signal from CPU of the CAD system. The software

that provides geometric modeling capabilities must be designed for efficient use of both by the

computer and the human designer. To use geometric modeling, the designer construct the

graphical image of the object on the CRT screen of the IGS system by inputting three types of

commands to the computer. The first type of command generates basic geometric elements

such as points, lines, and circles. The second command types is used to accomplish scaling,

rotation or other transformations of these elements. The third type of command causes the

various elements to be joined into desired shape of the object being created on the ICG system.

During this geometric modeling process the computer converts the commands intomathematical model, stores it in the computer data files and displays it as an image on the

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screen. The model can be subsequently being called from the data files for review, analysis or

alteration. The most advanced method of geometric modeling is solid modeling in three

dimensions. This method uses solid geometry shapes called primitives to construct the object.

Basically there are three types of modelling, They are:

a. Wire Frame Modelingb. Surface Modeling

c. Solid Modeling

Wire frame model Introduction:This is the basic form of modeling; here the objects drawn will be simple but more verbose,

geometric model that can be used to represent it mathematically in the computer. It is

sometimes referred as a stick figure or an edge representation of the object. Typical CAD/CAM

system provides users with possibly three modes to input coordinates: Cartesian, Cylindrical or

Spherical. Each mode has explicit or implicit inputs. Explicit input could be absolute or

incremental coordinates. Implicit input involves user digitizes..A wire frame model consists ofpoints, lines, arcs, circles &curves. Early wire frame modeling techniques developed in 1960s

were 2-dimensional. They are not centralized &associative. Later in 1970s the centralized,

associative database concepts enabled modeling of 3D objects as wire frame models that can be

subject to 3-dimensional transformations.

Wire frame entities:Wire frame Entities are divided into 2 types are:

a. Synthetic Entities: Splines & Curves

b. Analytic Entities: Points, lines, Circles, arcs, conics, fillet, chamfer

Surface Modelling:A surface model of an object is more complete and less ambiguous representation than it wire

frame model. It is also richer in associated geometric contents, which make it more suitable for

engineering and design applications. Surface model takes one step beyond wire frame models

by providing information on surfaces connecting the object edges. Creating a surface have

some quantitative data such as point & tangents & some qualitative data like desired shape &

smoothness. Choice of surface form depends on type of application.

Surface Entities:Similar to wire frame entities, existing CAD / CAM systems provide designers with both

analytic and synthetic surface entities. Analytic entities include plane surface, ruled surface,surface of revolution, and tabulated cylinder. Synthetic entities include the bicubic Hermite

spline surface, B spline surface, rectangular and triangular bezier patches, rectangular and

triangular Coons patches, and Gordon surface. The mathematical properties of some of these

entities are covered in this chapter for two purposes. First, it enables users to correctly choose

the proper surface entity for the proper application. For example, a ruled surface is a linear

surface and does not permit any twist while a B spline surface is a general surface. Second

users will be in a position to better understand CAD/CAM documentation and the related

modifiers to each surface entity command available on a system. The following are

descriptions of major surface entities provided by CAD/CAM systems

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Solid Modeling:A solid model of an object is more complete representation than its surface model. It is unique

from the surface model in topological information it stores which potentially permits functional

automation and integration. Defining an object with the solid model is the easiest of the

available three modeling techniques. Solid model can be quickly created without having to

define individual locations as with wire frames. The completeness and unambiguity of solidmodels are attributed to the information that is related database of these models stores

(Topology: It determines the relational information between objects.) To model an object

completely we need both geometry & topological information. Geometry is visible, whereas

topological information are stored in solid model database are not visible to user. Two or more

primitives can be combined to form the desire solid. Primitives are combined by

Boolean Operations. Different Boolean operations are:

1. Union(U)

2. Intersection(n)

3.Difference(-)

Solid entities:There are a wide variety of primitives available commercially to users. However, the four most

commonly used are the block, cylinder, cone, and sphere. These are based on the four natural

quadrics: planes cylinders, cones, and spheres.

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EXPERIMENT 1

Aim: To create a rectangle using extrude base/boss command.

Procedure:1. Open the new part drawing.

2. Select the front plane.

3. Go to normal to the selected plane and select sketch.

4. Go to sketch and pick up the rectangle drawing tool.

5. Now, go to the center of the selected plane and keeping the center as the midpoint, draw

a rectangle.

6. Select the smart dimension tool.

7. Select the breadth side of the rectangle and enter the dimension as 20mm.

8. Now, select the length side of the rectangle and enter the dimension as 40mm.

9. Now, go to exit sketch.

10. Select the extrude base/boss tool.11. Enter the extrude dimension as 20mm.

12. Click on ok.

Result: The specified drawing is complete.

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EXPERIMENT 1

Aim: To create a rectangle using extrude base/boss command.

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EXPERIMENT 2

Aim: To create a hollow rectangular block using extrude boss/base and extrude cut command.


2. Select the top plane.

3. Go to normal to the selected plane and select sketch.

4. Go to sketch and pick up the rectangle drawing tool.

5. Now, go to the center of the selected plane and keeping the center as the midpoint, draw

a rectangle.

6. Select the smart dimension tool.

7. Select the breadth side of the rectangle and enter the dimension as 20mm.

8. Now, select the length side of the rectangle and enter the dimension as 40mm.

9. Now, go to exit sketch.

10. Select the extrude base/boss tool.

11. Enter the extrude dimension as 20mm.

12. Click on ok.

13. Now go to the sketch tab and select the top plane for sketching.

14. Select the rectangle tool.

15. Select the center of the plane and draw a rectangle such that the center of the rectangle

and the plane coincide.

16. Now, select smart dimension and set the dimensions equal to 10X30 mm.

17. Exit sketch mode and go to the features pane.

18. Select the extrude cut tool and select the sketch.

19. In the extrude cut option panel select the cut through all option.20. Click ok.


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EXPERIMENT 3

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Aim: To create a hexagonal bolt using swept boss/base command and chamfer command.

Procedure:

1. Open the new part drawing.2. Select the front plane.

3. Go to sketch and select hexagon tool.

4. Select the center of the plane and draw a hexagon.

5. Use smart dimension to make the sides of hexagon equal to 20mm. .

6. Now, exit sketch and go to extrude tool.

7. Extrude the hexagon to 20mm. .

8. Go to sketch and select circle tool.

9. Draw a circle such that the center of the circle and the center of the center of plane and

hexagon coincide.

10. Use smart dimension to make the diameter equal to14mm. .

11. Exit sketch and go extrude command.12. Extrude the circle by 100mm. .

13. Now, select the top plane on the tip of the circular stem of the bolt and select sketch.

14. Go to the circle command and draw a circle of 14mm diameter on the plane.

15. Exit sketch and go to the feature tab and select helix/spiral tool under the curves

command.

16. Under the helix/spiral options, select height and pitch type of helix.

17. Enter the height as 100mm and pitch as 6mm. .

18. Now, select the tip of the helix and draw a triangular geometry on the tip of height 3mm

and base 5mm.

19. Go to the swept boss/base tool and then select the geometry and the helix as the path.

20. Click ok.21. Draw a circle on the top side of bolt which touches all the polygon sides internally.

22. Select fillet option in feature tab, in fillet select chamfer and enter distance 3mm and

angle 60.

23. Chamfer is done on hexagonal bolt.


EXPERIMENT 3

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Aim: To create a hexagonal bolt using swept boss/base command and chamfer command.

EXPERIMENT 4

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Aim: To create a helical gear using loft boss/base command.


2. Select the front plane.


4. Select the center of the plane and draw two circles.

5. Use smart dimension to make the circle of diameter equal to 10mm.

6. Now, exit sketch and go to extrude tool.

7. Extrude the circle by 3mm.

8. Go to sketch and select center line tool.

9. Draw a geometry specified in the drawing using the line tool on the surface of the

extruded circle.

10.Now, select the copy entities tool and select the opposite side of the extruded part and

copy the geometry to that side and select delete relationship.

11.Select the rotate tool and rotate the geometry on one side of the extruded part by 10o.

12. Exit sketch and go to the loft boss/base command.

13. Select the two geometries and loft the two geometries.

14. Now, select the circular geometry tool and select the lofted teeth.

15. Select the circular plane as the plane for pattern, and enter the number of patterns as 22.

16.Select the rectangle tool and make a rectangle of the specified on the inner circle of

diameter 4mm of the gear, for creating a notch.

17. Go to the extrude cut tool and select the rectangle and then select the cut through all

option.

18.Click ok.


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EXPERIMENT 4

Aim: To create a helical gear using loft boss/base command.

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EXPERIMENT 5

Aim: To create a simple spring using helix and spiral command.

Procedure:

1. Open the new part drawing.

2. Select the top plane.


4. Draw a circle of diameter 20mm.

5. Now exit sketch and go to the reference geometry tool in the features tab.

6. Select the helix and spiral tool and then select the circle.

7. Give the height of helix as 100mm and the pitch as 6mm.

8. Now, go to the circle tool and draw a circle of diameter 4mm at the tip of the helix such

that the tip of the helix is the center of the circle.

9. Go to the swept boss/base command and select the circle as the reference geometry and

the helix as the path.

10.Click ok.


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EXPERIMENT 5

Aim: To create a simple spring using helix and spiral command.

Image:

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EXPERIMENT 6

Aim: To create an Allen key using swept boss/base command.


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EXPERIMENT 6

Aim: To create an Allen key using swept boss/base command.

Image:

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EXPERIMENT 7

Aim: To create a base of a plumber block.

Procedure:

1. Open the new part drawing.

2. Select the front plane and select the line tool.

3. Draw the specified geometry.

4. Now, use smart dimension and make the sides of the geometry as specified in the

drawing.

5. Select the center line tool and draw a center line.

6. Make the distance between the center line and the inside of the geometry equal to20mm.

7. Now exit sketch and go to the revolve boss/base command.

8. Select the geometry as the entity to be revolved and then select the center line as the

axis.

9. Click ok.


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EXPERIMENT 7

Aim: To create a base of a plumber block.

Image:

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EXPERIMENT 8

Aim:To analyze a hook using Simulation Express.


2. Go to the tutorials section and open the Simulation Express.

3. Open the hookdrawing given as example in the tutorial.

4. Select the simulation express tool and start it.

5. Now, select the fixtures on the hook and click next.

6. Apply the load on the hook at the specified point and also give the amount and direction

of force. Enter the amount of force as 1500N in reverse direction.

7. Now, select the material of the hook. Set it to Alloy Steel.

8. Run the simulation.

9. Play the simulation and check if the hook is deforming as you had planned.

10. Now, select the Von Mises graph and print it.

11. Select the displacement graph and print it.

Result:The analysis is complete.

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EXPERIMENT 8

Aim:To analyze a hook using Simulation Express.

Image:

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Displacement analysis graph

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Von Mises stress analysis graph

Machine Design Lab-I

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Transcript of Machine Design Lab-I