Week 5:- Rest Unit & Clamp Unit Design Challenge

Rest Unit & Clamp Unit Design

Aim

• To Design 3 Different types of Power Clamp Unit with Different Riser, Blade and Clamp Arm for the given Car Panel.
• To Design 2 Different types of Rest Unit for the given Car Panel.

CLAMP UNIT

Clamp is device used to hold the workpiece temporarily and securely at the desired location with the help of clamping force. This unit is designed to clamp or hold the panel with NC blocks/

Mylar/ Rest by using a pnuematic cylinder.

PARTS OF THE CLAMP UNIT

MYLAR/ NC Block

• Mylar is the part that holds the panel from above and below during the operation.
• The top side of Mylar is called the clamping Mylar. Whereas, the bottom side Mylar is known as resting Mylar.
• Every Clamping Mylar will have a resting Mylar.
• It holds the panel in such a way that it does not deform during the welding process.
• A standard mylar may have dimension of 20*20mm. Depending on the angle of cros-section mylar may have shimming in one or two diemension. It is attached to other parts with help of bolts and dowels.

RISER

• A riser is a part that is used to raise the height of the fixture to attach the other componenets.
• The raiser is fixed to the base of the fixture and the blade is mounted on the riser. It can be in L shape, T shape or any other custom shape.

BLADE

Blades are plates that are attached to the riser to get to the required mounting height.

CLAMP

A Clamp is a device used to hold the part firmly in the assembly fixture and ensures no movement during operation on the part. The clamp must be placed in such a way that it does not

hinder the operation.

CLAMP PLAN

The clamp plan shows the area where the part can be clamped without any damage. The clamp plan data is usually provided by the customer. It gives the details on the location of pins, rest units, Clamp units, Dumps, etc. The clamping locations is given in form of coordinates.The clamp position in some cases will be in such a way that it might damage the tool, or very near to pin position. In such cases, We should not take the decision to change the clamp plan without discussing it with the customer. Typical parts of a clamp unit are as follows.

FINGER / CLAMP MYLAR

A Finger is an NC Block, Which is mounted on the Clamp arm of the cylinder, and will press the car panels towards the rest, so it holds the car panel.

REST Rlock

Rest is an NC block, which is fixed to the unit to support the car panel, also it resists the clamping force of the finger, and thus clamps the car panel.

Shims

Shims are strips of metal used to adjust the part alignment with height adjustment upto some extent. Shims can also be referred as washers. These can be incorporated between blocks to make minor adjustments. It thickness ranges from 0.25 to 2mm. It is generally made of SAE grade cold rolled steel and coating of black oxide may be provide for corrosion resistance.

CLAMP ARM

A Clamp arm is a bought-out part, to which all the movable parts are fixed. In general, a clamp arm is a part of a clamp cylinder. They are available in different bore size and hole pitch.

EXAMPLE

Middle arm - A10

Right arm - A11

Left arm - A12

CLAMP CYLINDER

A Clamp Cylinder is a pneumatic device that works with pressurized air. The Clamp cylinder is used to open and close the parts fixed to the clamp arm fixed to the clamp body. Clamp arms are generally bought out parts and the major manufacturers are tunkers and destaco. They are available in various bore sizes like 50mm, 63mm, 80mm.

3-2-1 Principle

It is an work-holding principle where three pins are used to locate the part. The 1st principle plane either XY, YZ, ZX and the second pin is located on the 2nd plane which is perpendicular to the 1st plane, and third pin on the plane which is mutually perpendicular to the 1st and 2nd planes, this arrangement constrains the movement of the workpiece along all three axes. Thus, the 3-2-1 principle is used to restrict the 12 degrees of freedom of a part.

Rest Unit

This unit is used to rest/support the panel. Proper flat surface should be chosen so the panel can rest without any deviation. No clamping force is applied to rest the panel on the rest unit. It is generally used in combination with locating unit or clamp unit to save cost.

Parts of the Rest unit

• NC Block
• Spacer/ shim pack
• Blade
• Riser

A Simple Support/ Rest unit

Rest Unit 1

Rest Unit 2

Clamp Unit 1

Clamp Unit 2

Clamp unit 3

Assembly Images

Conclusion

Thus the 3 Different types of Power Clamp Unit with Different Riser, Blade and 2 Different types of Rest Unit for the given Car Panel is designed using the catia v5.