CAD Record

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WELDING

Introduction

Welded joints are used where parts are to be joined permanently. Welding is also used to

fabricate parts instead of casting or gorging. Parts produced like this are light, strong and economical

also. To form a welded joint, the part to be joined are heated to a high temperature either by electric

arc or gas, up to fusion temperature and then a filler material is used to fuse along with the base parts.

The high temperature fuses the metals completely with each other. On cooling, the joint is formed that

is as strong as the base part.

Specifying a Welded joint

A weld symbol shows only the groove shape, while a welding symbol consists of many

other elements as described and shown in fig 1(A) and 1(B) for arrow towards right and left

respectively.

For example, the welding symbol shown in fig 1(C) gives the following information:

Weld size is 8 mm (The left most element on reference line).

Groove shape is double V with groove angle 60.

Root opening not indicated hence taken as zero.

Welding is on both sides as the weld symbol is on top and bottom of the reference line.

Weld metal forms convex surface and letter M indicates that the weld surface is to be

machined.

Welding is done for 20 mm length leaving a blank length of 10 mm.

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WELDING JOINTS

WELD SYMBOLS

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WELDING SPECIFICATIONS


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RIVETED JOINTS

Introduction

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Classification of Riveted Joints

Riveted joints can be classified as under:

Riveted Joint

TYPES OF RIVET HEADS

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Chain Zigzag

Lap Joint Butt Joint

Single cover plate or double cover plate

Single

riveted

Double

rivetedTripple

rivetedSingle

riveted

Double

riveted

Tripple

riveted

Chain Zigzag Chain Zigzag Chain Zigzag


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BOLTS AND NUTS

Introduction

All machines are composed of separate parts which are held together by some joint. The

joint may be permanent like welding, riveting or temporary using bolts and nuts. This later provides

the advantage that the parts can be separated whenever required. Bolts and nuts are mostly used for

temporary fastenings. Standardization of such widely used product is necessary for interchangeability.

A bolt is a cylindrical part having a hexagonal or square head on one side and threads,

partially or completely on the cylindrical part. The counter part of the bolt is a nut that is also either

hexagonal or square and his internal threads with same pitch as that of the bolt.

The part to be joined together are drilled with a hole of the same size as the body diameter

of the bolt or slightly more for easy insertion. The bolt is then passed through the part to be joined

and then the nut is tightened on the threads of the bolt. When the nut is rotated, it advances on the

threaded body of the bolt and clamps the parts.

A washer is placed below the nut so that the surface of the part is not spoiled due to

tightening of the nut. It also increases the contact area, thereby reducing the local intensity of stress.

Fig14.1 shows an assembly of to parts with bolt, nut and washer.

Lock Nut

A lock nut is an additional nut placed theoretically below the main nut (fig14.9A). Its thickness is

2/3

rd

of the standard nut. The arrangement of placinglock nut below the main nut causes problems while

tightening, if head thickness is lesser than thickness of

spanner. Therefore, sometimes lock nut is placed above

the main nut (14.9B). For a lock nut, both the surfaces,

i.e top and bottom are chamfered.

While using, first tighten the lock nut. Then holding the

lock nut by a spanner, tighten the main nut with another

spanner. This causes tension at the threaded surfaces.

This force keeps both the nuts tight and thus they are

prevented from loosening.

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SCREWS

A screw is smaller in size both for diameter and length than a bolt, and has threads for the entire

length of the shank. The head is not hexagonal but circular. The various shapes of the heads used for

the screws are shown in Fig14.7. There are many types of screws as follows

1. Cap screw

2. Machine screw

3. Set screw

4. Wooden screw

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KEYS

A shaft is used to transmit power but generally not alone. Power is transmitted through pulleys and

belts, gear or sprokets. These machine components are to be fixed on the shaft such that they do not

slip while transmitting torque. To fix these components on shafts, a key is used. Keys are made of

steel to withstand both shear and compressive stresses caused during power transmission.

Key is a machine component, inserted between shaft and hub of the rotor to prevent circumferential

relative movement between them. It is shown in fig.16.3. keyway is the groove milled on the shaft

and its mating part. Key is inserted in these grooves after aligning them.

Keyway can be made either by a vertical milling machine (fig. 16.4A) or by horizontal milling

machine (fig. 16.4B. A vertical milling machine gives constant depth for the whole length but the

ends are semi-circular. A horizontal milling machine gives variable depth at the ends of the keyway.

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Saddle Keys

Saddle keys are only in hub and not in shaft. They are likely to slip and hence used only for light

work. They transmit torque only by friction between the metallic surfaces. It thickness is kept D/12

and width as D/4 where D is the shaft diameter (Fig 16.5). A taper of 1:100 is given on thickness.

Only frictional force is used to keep them in position. Their bottom face can be flat or hollow.

Thickness at the thicker end is called nominal thickness.

For a flat key, the shaft is also made flat at the position of key (Fig. 16.5A). A Hollow key (concave

key) has the same curvature at the bottom as the shaft. The shaft is not modified at all (Fig16.5B). Flat

key is slightly superior to hollow keys as the flat surface of the shaft resists relative motion.

Sometimes a set screw is also used for light applications to tighten the hub on the shaft (Fig.16.5C),

e.g. ratio knobs are tightened with a screw on its side.

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FIT AND TOLERANCE

TOLERANCE:

A tolerance is the total amount by which a specific dimension may vary; thus, the tolerance is the

difference between the maximum and minimum limits.

Types of Tolerance:

1. Unilateral Tolerance:

A unilateral tolerance is a tolerance in which variation is permitted only in one direction

from the specified dimension. Example: 1.400 +0.000/-0.006

2. Bilateral Tolerance:

A bilateral tolerance is a tolerance in which variation is permitted in both directions from a

specified dimension (example 0.005)

Fit:

Fit is general term used to signify the range of tightness or looseness, which may result from the

application of a specific combination of allowances and tolerance in the design of mating part

features. Fits are four general types: Interference, transition, line and clearance.

1. Interference Fit:

An interference fit is one having limits of size so prescribed that an interference

always results when mating parts are assembled.

2. Transition Fit:

A transition fit is one having limits of size so prescribed that either a clearance or an

interference mat result when mating parts as assembled.

3. Line Fit:

A line fit is one having limits of size so prescribed that surface contact or clearance

may result when mating parts as assembled.

4. Clearance Fit:A clearance fit is one having limits of size defined such that a clearance always results

when mating parts are assembled.

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INTRODUCTION TO SOFTWARE

DWGeditor is designed for anyone who wants a fast and efficient CAD program with all the power

and versatility of standard programs such as AutoCAD by Autodesk, Inc., or MicroStation by Bentley

Systems, Inc., at an affordable price. Using today's advanced technology, DWGeditor integrates the

Microsoft Windows interface with a powerful CAD engine.

DWGeditor provides unparalleled compatibility with AutoCAD, using most of the same file formats

including those for drawings (.dwg files), linetypes, hatch patterns, and text styles. You can also use

AutoCAD menu files and run AutoLISP by Autodesk, Inc., programs. If you have written your own

ADS (AutoCAD Development System by Autodesk) programs, simply recompile them to link withthe DWGeditor libraries provided on your compact disc. Many third-party ADS programs already

support DWGeditor. If you have a program that is not already supported, ask your software vendor to

provide an IntelliCAD-compatible version of their program.

DWGeditor is more compatible with the AutoCAD program than any other CAD product, delivers ad-

ditional tools with advanced CAD features, and has a seamless Microsoft Windows integration. This

powerful program provides a superb combination of features for CAD users like architects, engineers,

and designers.

DWGeditor incorporates all the standard features found in other CAD programs, along with features

and capabilities you won't find anywhere else. Its multiple-document interface (MDI) lets you open

and work with several drawings at the same time. You can easily copy drawing entities between

drawings. In addition, the powerful Drawing Explorer lets you manage information and settings and

quickly copy layers, linetypes, and other information between drawings.

When you start DWGeditor, the program automatically creates a new drawing based on a template

drawing, DWGeditor.dwg. This template includes predefined settings such as drawing units, text size,

and drawing area. You can either use these settings or change them according to your needs. There is

nothing unique about a template drawing. You can use any drawing as a template for future drawings.

You can save many steps by basing a new drawing on an existing template. By doing this, a new

drawing will contain all the settings and entities you need. When you open a new drawing from your

custom template, you can modify existing settings and delete any entities that you don't need.

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Ex.No:1Plummer Block

Date:

Aim:

To draw the assembled view of the plummer block using given part drawing.

Software Used:

Solidworks2009 DWG editer

Tools used:

A system loaded with Solidworks DWG editer an a printing device.

Sketch of the plummer block with dimension indicated.

Make a hard copy using printer.

Command used:

Limits

Zoom

Line

Circle

Offset

Arc

Trim

Polygon

Copy

Move

Mirror

Hatching

Dimension Linear, radius command.

Procedure:

Open Solidworks DWG editer and select the new from file menu.

Set the limits as per the required space of given plummer block.

Set the grid required from the plummer block.

Drawn the assembled view of plummer block using above said commands.

Mark the dimensions and gave the orthographic views before making a hard copy.

Result:

Thus the assembled views of the plummer block were drawn from given part drawing and

hard copy was taken using printer.

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Ex.No:2Flanged Coupling

Date:

Aim:

To draw the assembled view of the Flanged Coupling using given part drawing.

Software Used:


Tools used:


Sketch of the flanged coupling with dimension indicated.


Command used:

Limits

Zoom

Line

Circle

Offset

Arc

Trim

8. Polygon

9. Copy

10. Move

11. Mirror

12. Hatching

13. Dimension Linear, radius

command.

Procedure:


Set the limits as per the required space of given flanged coupling.

Set the grid required from the flanged coupling

Drawn the assembled view of flanged coupling using above said commands.


Result:

Thus the assembled views of the flanged coupling were drawn from given part drawing

and hard copy was taken using printer.

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Ex.No:4Universal Coupling

Date:

Aim:

To draw the assembled view of the universal coupling using given part drawing.

Software Used:


Tools used:

1. A system loaded with Solidworks DWG editer an a printing device.

2. Sketch of the universal coupling with dimension indicated.

3. Make a hard copy using printer.

Command used:

1. Limits

2. Zoom

3. Line

4. Circle

5. Offset

6. Arc

7. Trim

8. Polygon

9. Copy

10. Move

11. Mirror

12. Hatching


command.

Procedure:

1. Open Solidworks DWG editer and select the new from file menu.

2. Set the limits as per the required space of given universal joint.

3. Set the grid required from the universal coupling

4. Drawn the assembled view of universal coupling using above said commands.

5. Mark the dimensions and gave the orthographic views before making a hard copy.

Result:

Thus the assembled views of the universal coupling were drawn from given part drawing

and hard copy was taken using printer.

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Ex.No:5Horizontal Stuffing Box

Date:

Aim:

To draw the assembled view of the horizontal stuffing box using given part drawing.

Software Used:


Tools used:


Sketch of the horizontal stuffing box.with dimension indicated.


Command used:

1. Limits

2. Zoom

3. Line

4. Circle

5. Offset

6. Arc

7. Trim

8. Polygon

9. Copy

10. Move

11. Mirror

12. Hatching


command.

Procedure:


Set the limits as per the required space of given horizontal stuffing box.

Set the grid required from the horizontal stuffing box.

Drawn the assembled view of horizontal stuffing box. using above said commands.


Result:

Thus the assembled view of the horizontal stuffing box was drawn from given part

drawing and hard copy was taken using printer.

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KNUCKLEJOINT


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Ex.No:6Lathe Tail Stock

Date:

Aim:

To draw the assembled view of the lathe tail stock using given part drawing.

Software Used:

Solidworks2009 DWG editer.

Tools used:


Sketch of the lathe tail stock.with dimension indicated.


Command used:

Limits

Zoom

Line

Circle

Offset

Arc

Trim

8. Polygon

9. Copy

10. Move

11. Mirror

12. Hatching


command.

Procedure:


Set the limits as per the required space of given lathe tail stock.

Set the grid required from the lathe tail stock.

Drawn the assembled view of lathe tail stock using above said commands.


Result:

Thus the assembled view of the lathe tail stock was drawn from given part drawing and


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Ex.No:7Connecting Rod

Date:

Aim:

To draw the assembled view of the connecting rod using given part drawing.

Software Used:

Solidworks2009 DWG editer.

Tools used:


Sketch of the connecting rod.with dimension indicated.


Command used:

Limits

Zoom

Line

Circle

Offset

Arc

Trim

8. Polygon

9. Copy

10. Move

11. Mirror

12. Hatching


command.

Procedure:


Set the limits as per the required space of given piston and connecting rod.

Set the grid required from the connecting rod.

Drawn the assembled view of connecting rod using above said commands.


Result:

Thus the assembled views of the connecting rod were drawn from given part drawing and


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Ex.No:8Screw jack

Date:

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Ex.No:9Multi plate clutch

Date:

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Ex.No:10Safety Valves

Date:

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