Week 7- Base Unit Design Challenges 2

Challenge-7 week-7 Base unit design Challenge-2

Aim:
Design a base units for the units designed such as pin and clamp units in the previous challenge with all weldments for the given car panel. Design the complete fixture assembly and constrained the panel using 3-2-1 principle.

Introduction

Base Unit
All other assembled units, such as clamps, pins, and swivels, are secured to a base unitpresented in the below figure. Other components required for operation include the valve box, Trunking channel, base plate, measuring hole cover, eye bolt, pedestal, weld bars, and floor plate, which are all included with the base unit. A trunking cable path is also supported by the base unit. The base plate is made of steel and aluminium and ranges in thickness from 25 to 40 mm. A number of holes in the base plate have been drilled to serve as mounting points for the clamp unit, pin unit, and so on. A base plate size must be designed with the BCS co-ordinate system in mind, as it covers all units with its outer peripheral individual opening.

The procedure for creating the base unit is as follows:-

• A Rectangular Base plate is created with required dimensions, and make sure that every unit must be inside by around 25 mm from the outer edge.
• Further base plate is supported by square tube with good strength (50x50x3mm) from all four side. Also one middle support is provided for betters support.
• Below the base plate small square plates are created for mounting of base plate and legs.
• Further four Pedestal (resting legs) were created with square tubes.
• Finally, the lower plate for the leg to stay were created which will support the base leg.

3-2-1 principle Used for restricting the degree of freedom of panel.

Any 3D body/part has three axes that run along the x, y, and z axes. It has the ability to move along any of these axes or to direct its movement to one of these three axes. The body can rotate around these axes at the same time. As a result, the total amount of freedom with which the body can move is six. All degrees of freedom (DOF) must be restricted to process the body by arranging suitable locating points and then clamping it in a fixed and required position.

Locating a part to be machined involves mainly three steps: Supporting, Positioning, and Clamping. All fixtures work on 3-2-1 principle. The best and the most cost effective method of part location is referred to as the 3-2-1 method.

To establish the part plane, three locator blocks are used. Three locators or supports are positioned beneath the workpiece. The primary locating surface is usually equipped with three locators. The 3-2-1 method restricts 6 degrees of freedom by introducing a minimum of 1 clamping and 2 pin unit. The clamp unit restricts two axial movements, one upward and one downward. The other two pin units limit radial movement.

By employing 3-2-1 principle, the degrees of freedom were restricted fully for the give panel as presented in the below figure. And all the units were mounted on the base unit.

Different units were used to restrict the movement as presented in the below figures, so any operation can be done properly.

Total units used to restrict the movements-

Total swivel clamp with pin: 05
Total clamp units:03
Total pin units: 05

Orange panel restricted by one swivel clamp with pin and one pin unit and blue panel is restrcted by one clamp and one swivel clamp with pin and one pin unit.

Normal view of Fixture assembly.

Conclusion:
The movements of the given panel were restricted by using the 13 different units by considering all the parameters. The 3-2-1 principle was used to each part separately to restrict the overall degree of freedom of the given panel.