Week 11- Assembly Workbench
OBJECTIVE: To create a quick return mechanism and CV joint parts in the part workbench or generative workbench and assemble
them following all the guidelines.
SOFTWARE USED: CATIA V5.
INTRODUCTION:
a) QUICK RETURN MECHANISM:
A quick return mechanism is an apparatus to produce a reciprocating motion in which the time is taken for travel in return stroke
is less than in the forward stroke. It is driven by a circular motion source (typically a motor of some sort) and uses a system of links
with three turning pairs and a sliding pair.
There are three types of the quick return mechanism
1. Hydraulic drive
2. Crank and slotted link mechanism
3. Whitworth mechanism
A quick return mechanism is a mechanism that produces a reciprocal effect so that the system takes less time in the return
stroke while comparing with forwarding stroke. In the quick-return mechanism, a circular movement like the crank and lever
mechanism is converted into reciprocal movement but the return time is different from the forward moment. In several
applications, this process is used. Some of them are shaper, slotter, screw-press, mechanical drive, etc. The time required for
cutting is reduced with the assistance of a quick return mechanism.
b) CV JOINT:
Constant-velocity joints (also known as homokinetic or CV joints) allow a drive shaft to transmit power through a variable angle, a
constant rotational speed, without an appreciable increase in friction or play. They are mainly used in a front-wheel-drive vehicle
Modern rear-wheel-drive cars with independent rear suspension typically use CV joints at the ends of the rear axle half-shafts and
increasingly use them on the drive shaft.
All front-wheel-drive cars have Constant Velocity joints or CV joints on both ends of the drive shafts (half shafts). Inner CV joints
connect the drive shafts to the transmission, while the outer CV joints connect the drive shafts to the wheels. Many rear-whee
drive and four-wheel drive cars, as well as trucks, also have CV joints.
The CV joints are needed to transfer the torque from the transmission to the drive wheels at a constant speed while
accommodating the up-and-down motion of the suspension. In front-wheel-drive cars, CV joints deliver the torque to the front
wheels during turns. There are two most commonly used types of CV joints: a ball-type and a tripod-type. In front-wheel-drive
cars, ball-type CV joints are used on the outer side of the drive shafts (outer CV joints), while the tripod-type CV joints are mostly
used on the inner side (inner CV joints).
PROCEDURE:
1)First create all the parts of QUICK RETURN MECHANISM as well as of CV JOINT.
2)Create all the parts separately in the part workbench or generative workbench.
3)First create the sketch of the part in the sketching workbench and make sure that the sketch is Iso constraint.
4)Then pad that sketch using pad feature in a part workbench or extrude and trim accordingly in generative workbench.
5)Use Boolean operations and add or remove to obtain the required output.
6)While creating the parts in a generative workbench make sure that you close the surface of the part you created.
7)Create all the parts and save the CAT. Part of all the parts that you have created separately.
8)Then go to the assembly workbench and open all the parts that you created using the “open existing component” feature.
9)Then assemble them accordingly using the constraint toolbox and move the parts in various directions as you need using movable
toolbar.
COMMANDS USED:
1.PAD
2.UNION TRIM
3.EXTRUDE
4.EXTRAPOLATE
5.TRIM
6.SPLIT
7.CLOSE SURFACE
8.COINCIDE
9.CONSTRAINT
10.MOVE
CONCLUSION:
The quick return mechanism and cv joint assembly has been done following all the guidelines