Week 7:- Base Unit Design Challenges 1

Q1- What is the base unit? what are the typical parts of the base unit?

Ans- A Base unit is the unit designed to mount all the other units ( Clamp unit, Pin unit, Rest unit etc.) of the tool also other parts necessary for a tool like pneumatic valve box, trunking cable path will also be mounted on to a base unit.

PARTS OF BASE UNIT

a) Base plate : Base plate is a machined plate of 25 to 40 mm thickness made of steel and aluminium on to which the holes are drilled to mount the individual units like clamp unit, pin units etc. of a tool.

b) Pedestal : A pedestal is a part which connects the base plate to the floor plate. A pedestal is a standard part in general and in some cases it can be a welded frame integrated with the base plate.

• A standard Pedestal can be of different height and different sizes.
• Depends on the size of the base plate, the number of pedestal varies for load distribution.
• A pedestal are of different types with different inclinations.

c) Valve box : Valve box is a standard part which will accomodates all the pneumatic valves for the units.

d) Eye bolt: Eye bolts are used for the transporting of the tool, using lift hooks, fork lift holes will also be provided in some cases for transporting purpose.

e) Floor plate : Floor plate is grouted to the floor with fixed bolt on the ground. Floor plates are also called as Foundation plates.

f) Trunking channel : It is duct that carries all the electrical and pneumatic connections (wires and pipes) for units of the tool.

It has very minimal thickness.

Q2 What are the points need into account while designing the base units ?

Ans-2 Fundamentals of base plate design:

• A base plate size should cover all the units with its outer periphery including opening.
• A base plate is preferred to be designed with respect to BCS Coordinates.
• A base plate should be drilled with datum holes / measuring holes in line with a pitch of 1000 mm in general.
• Number of datum holes is depend on the size of the base plate.
• Datum holes should be drilled at nominal values of coordinates and in terms of 50 and 100 (In general)
• Datum holes should be drilled with dia100 mm away from other units.
• Datum hole should be covered with cover plates.

Few points need to consider for floor plates :

• There will be a clearance of 10mm maintained between the pedestal base plate and the floor plate.
• This clearance will be used by the levelling screws for levelling th entire tool.
• Weld bar are to be used to weld the positions permanently after levelling is done.
• A weld bar is a plate along the sides of the base plate of the pedestal.

Gun study

Gun study is a process where positioning of spot gun or weld torch is to be checked, to avoid clash between gun and other parts of the fixture and check the gun feasibility.

In this process designer usually takes the gun tip to respective spot or weld position at various orientation and checks if there are any clashes between any part of the gun and fixture.

Q3 What is a dump unit?

A dump unit is a unit in which an assembly of other units like pin unit, rest unit, clamp unit etc. is mounted on a large bore of cylinder sufficiently enough to validate the total load due to various units.

A dump unit is basically used in conditions where we have constraints the mount panel from above the main part or constraints with gun positioning.

Q4- What are the points we need to consider while designing the dump unit ?

Ans- Points we need to consider while designing the dump unit.

• Dump unit need not necessarily to be used in fixture design, It depends on the condition and various constraints.
• Dump cylinder validation must be done as per the total weight mounted on the cylinder.
• Shock absorbers must be implemented to avoid vibrations.
• Proper opening and closing of dump unit must be checked.
• Frame mounting the dump unit should have strength to bear different static and dynamic loads.

Q5 - What is a slide unit?

A slide unit is a unit in which an assembly of other units like pin unit, rest unit, clamp unit etc. is mounted on a sliding mechanism with the help of cylinders.

A slide unit is basically used in conditions where we have constraints to mount a panel to slide in to the main assemb;y or constraints with gun positioning.

Q6 - What are the points we need to consider while designing the slide units?

Ans - Points we need to consider while designing the slide unit.

• Slide unit need not necessarily to be used in fixture design, it depend on the conditions and various constraints.
• Slide cylinder validation must be done as per the total weight and force exerted on the cylinder.
• Shock absorbers must be implepented to avoid vibrations.
• Proper opening and closing of slide unit must be checked.
• Sensors should also be provided to ensure the position of slide unit in automation.
• Mechanical stoppers need to be provided for positioning.
• Sliding mechanism can be formed through various means such as LM-rails and guide, Ball screw, manual, cylinders, motors etc.