Week 6:- Clamp Unit & Pin-Clamp Unit Design Challenge

AIM: To design and understand the concept of Swivel Clamp Unit & Pin Clamp Unit.

CLAMP UNIT:

A clamp unit is a unit designed to clamp/hold the car panel with NC blocks/Mylar/Rest by using a pneumatic clamp cylinder.

The different parts of a clamp unit are:-

Clamp Mylar/Finger: Finger is a NC Block which is mounted on the clamp Arm of the cylinder and will press the car panel towards the rest, So that it holds the car panel.

Rest Mylar: A rest mylar is a NC block which is fixed to the unit to support the car panel, Also it resists the clamping force of the finger and thus clamp the car panel.

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 clamp cylinder.

• Clamp arms are different for different bore of the cylinder
• Clamps arms are available in different hole pitch
• Clamp arms are available as :
• Middle Arm – A10
• Right Arm – A11
• Left Arm – A12

Clamp Cylinder: A clamp cylinder is a pneumatic device which works with pressurised air. The clamp cylinder is used to open and close the parts fixed to the clamp arm fixed to the clamp body.

• Clamp cylinders are Bought out parts. Some of the manufacturers are: Tunkers and Destaco
• Clamp cylinders are in general 40,50.63 and 80 bore capacity
• Opens up to 135 degree for horizontal clamp mounting
• Opens up to 105 degree for vertical clamp mounting

PIN UNIT:

Fixed pin unit is a unit designed to locate the car panel using pins.

The pin unit is used to restrict the degrees of freedom of a part while welding operation.

Components of a Pin Unit:

Pin:

• Pin is a part which locates the car panel.
• A pin can either be a make part or a standard part.
• Pin should have grinding surface on shaft with fits on to which the pin retainer will be fitted.
• The mounting surface of the pin should be a fine machined surface.
• The pin should have a step machine surface to lock the rotation, which matches with the pin retainer.
• The mounting surface of the pin retainer to the blocks should be a machined surface.
• Pin must have a fastening provision like tapped hole from the bottom or a V grove from the side.

Pin Retainer:

• Pin Retainer is a part which holds the pin in position, the pin retainer can either be a make part or a standard part.
• Pin retainer should have a hole with a fit, on to which the pin will be fixed.
• The pin mounting surface of the pin retainer should be a fine machined surface.
• The pin mounting surface of the pin retainer should have a step to lock the rotation of the pin.
• The pin retainer will be fixed to a block or a L block to the riser with 2 dowel holes(pins) and at least with one screw hole to maintain the tolerance.

Block/L Block: These parts are mainly used to accommodate the shimming directions as per fundamental in general. Also in some cases these are used for other design feasibility.

Shims/Spacers: Shims and spacers are some standard parts which are used for adjustments of locators (NC Blocks and Pin retainers) for obtaining the desired values for the precise working of a unit with respect to car part. In general, to adjust the Design to manufacturing deviation.

Blade: Blade is part like a plate, which connects the parts of a unit to a riser. In general the blade can be either a make part or a standard part.

Riser: Riser is a part on which all the parts of a unit are mounted, and it is mounted on the base plate of a tool. In general, the riser can either be make part or a standard part.

Dowel holes and machined surfaces: All make parts which are to be assembled with tolerance should be designed with 2 dowel holes and at least of 1 to 6 threaded/free hole. And to be fine machined for the mounting surface with 3 to 5 mm step machining.

Process Followed to Design the Swivel Clamp Units & Pin Clamp Unit:

• Launch the CATIA V5 application and create new product file as (P002_Z02_ST02_00_00)
• Create another five product files into the main product file as (P002_Z02_ST02_00_00_COMPONENT),(P002_Z02_ST02_01_00_SWIVEL_CLAMP_UNIT),(P002_Z02_ST02_02_00_SWIVEL_CLAMP_UNIT), (P002_Z02_ST02_03_00_SWIVEL_CLAMP_UNIT) & (P002_Z02_ST02_04_00_PIN_CLAMP_UNIT)
• Into the (P002_Z02_ST02_00_00_COMPONENT) file add the car panel
• And into the (P002_Z02_ST02_01_00_SWIVEL_CLAMP_UNIT) product file create multiple part files for clamp mylar,rest mylar,clamp arm,swivel cylinder,blade,riser & stopper
• Double click on the clamp mylar part file, select the plane and sketch the mylar profile then pad it for 20mm.Create dowel holes.
• Follow the exact same procedure to make rest mylar
• Using snap/smart move allign both the mylar with respect to the car panel
• Add the swivel cylinder part file which was provided
• Create the clamp arm using pad command
• Allign the clamp arm with swivel cylinder
• Into the clamp arm part file insert additional body and create the two plates
• Create the blade such that it is properly alligned with cylinder and clamp arm plates
• Make a stopper block to place between the blade and clamp arm
• Select the riser part file sketch the profile for riser and pad it.Also create the dowel holes
• Provide necessary fillet/chamfer to parts
• Make sure all the parts are accurately placed in their desired location
• Make sure all the dowel holes are properly alligned
• For a pin clamp unit form a pin,pin retainer,L block & arm and attach it to the riser