Week 3:- BiW Fixture Design Methodologies Challenges
Que 1st Ans:-
Design Methodology
It is nothing but steps followed during the concept of design stages of fixture design. The Design Methodology includes the following parameters:-
1] Purchase Order
2] Input from Customers
3] Percentage completion criteria
4] Design Output
Que 2nd Ans:-
Input from Customers are as follows:-
1] Functional Requirements
2] Preferred standard Components
3] Car Products
4] Layout
5] Ergo Data
6] Weld Study
7] Standard Detailing Templets
Que 3rd Ans:-
Input from Car Product includes:-
1] GD & T
2] Part List
3] Cad Files of Car Parts
4] Clamp Plan
5] Product Assembly Process sheet
Que 4th Ans:-
The Clamping plan of the part is the plan which defines the location of the clamp, pin, rest, dumps, etc while doing the operation to ensure the geometry of the assembly.
Que 5th Ans:-
The fixture layout depicts the arrangement of locators and clamps around the workpiece. The position of the locators and clamps is one of the major factors which cause the elastic deformation of the workpiece during machining.
Fixture Provides Information of
- Flow of parts
- Robot Stations
- Pitch Stations
- Accessories like tool changers and tip dressers
- Sub Assembly links
- Platform height
- Loading / Unloading Sequence.
Que 6th Ans:-
Ergo data. Ergonomics defines as the study of human behaviour and movements. The ergo data like the height, distance from the fixture is given as an input by the customer and the design of the fixture must adhere to these data. This design will result in ease of operation for the operator of the fixture.
Que 7th Ans:-
Weld Study includes:-
1) Weld Gun Details
2) Weld Matrix & Weld Points
A] Geo Weld Points
B] Re- Spot Weld Points
Que 8th Ans:-
Percentage completion Criteria
Percentage Completion Criteria is followed by the design stages and dispatched stages of the welding fixtures.
0-25% Input and concept design.
25-40% Concept approval and simulation.
40-85% Design freezing and detailing.
85-100% Check and Final dispatch.
Que 9th Ans:-
-The output is 3D models and the 2D drawing of the tools.
- Utilized tools required two types of drawing sheets
- Key sheet in the index of units and their placement on the tool base
- Layout sheet a detailed fitting of the individual units to include all their components
The Output should compile the following points
- Approved standard component to be used where possible
- Design must be as simple and economical as possible
- Design must comply with all current safety and ergonomics requirements
- Design must provide for controlled and damaged free handling of product
- Adequate error-proofing provision must be incorporated into each design by providing Proximity switches, rough locators etc.
-The weight of the moving parts must be kept to a minimum while maintaining maximum strength
- Frames and structures ate to be simpler and sturdy
- Design clearance and accessibility for routine maintenance and service
- Motion control must be considered on any moving types of equipment
- Designer is responsible to validate clamps and all weld guns.
Que 10th Ans:-
Structuring a design tree
- Structuring a design tree implies a process where all the assemblies and parts are named in specific standards different customers have a set of standards to structure a design tree
- It is an important process that helps us to identify a specific part of the assembly as to which project tool or unit it belongs to
- This helps us to avoid errors during design study manufacturing assembly inspections etc
- If the parts are assembled ate not named properly on the design tree is not structured properly it will create confusion to understand the design may create major possibilities of making errors
- It can help us to identify the number of items the same type of different types that ate being used in an assembly.
Que 11th Ans:-
In general, a unit is a device having a specific function, especially one forming part of the complex mechanism
The TYpes of Units are as follows:-
1] Simple Unit
A) Rest Unit
B) Fixed Pin Unit
C) Retract Pin unit
D) Rough locator unit
E) Sensor UNit
F) Base UNit
2] Complex Unit
A) Slide Unit
B) Dump Unit
Que 12th Ans:-
A fixed pin unit is a unit designed to locate the car panel using pins. The purpose of a fixed pin unit is to locate the pin at a specific location that does not change the orientation of the workpiece.
Fixed Pin has the following components:-
- Pin
- Pin Retainer
- Shims/ Spacers
- Block
- Blade or adapter plate
- Riser
Que 13th Ans:-
Parts of Fixed Uni are as follows:-
- Rest unit.
- Fixed pin units.
- Retract pin units.
- Rough locator unit.
- Sensor unit.
- Base unit.
Que 14th Ans:-
Rest Unit
A Rest unit is a unit designed to rest/ support the car panel using NC blocks/ Mylars/ Rests.
It contains the following parts:-
- Clamp Arm
- Finger
- Backup/Rest
- Shims/ Spacers
- Plate
- Pneumatic Clamp Cylinder
- Stander Riser
Que 15th Ans:-
Fundamentals Of Sensor Unit Design
- Every single base panel which are being welded in a tool should be sensed
- Each panel should be sensed by 1 or 2 sensors depending on the size of the panel Preferred to be in diagonal opposite ends to the panel
- Every sensor should be mounted in a 3 directional adjustable way in general
Types of Sensors Used in General
1] Proximity Sensor
2] LASER sensor
3] Photoelectric sensor
Que 16th Ans:-
Rough locators are majorly used in manual fixtures. The rough locators will guide the operators to place the part in the correct position and orientation. The rough locator can be a standard part or take part.
Fundamentals of Rough Locators
- Rough locators should be placed at the edge of the car panel, which has to guide
- Rough locator has to be placed at the same angle of the car part edge with a minimum distance
- Rough locator has to be placed at the same angle of the car part edge with a minimum distance of 2.5 mm from the edge of the car part
- Rough locators should start guiding the panel before 10 to 15 mm to the start of the pin engagement.
- The slots should be in the direction of the car body part guiding
Que 17th Ans:-
Base Unit is the unit designed to mount all the other units of the tool also other parts necessary for a tool like parametric valve box, trucking cable path will also be mounted on to a base unit
Parts in Base unit:-
- Trunking channel
- Baseplate
- Valve Box
- Measuring hole cover
- Eyebolt
- Pedestal
- Weld Bars
- Floorplate
Que 18th Ans:-
A dump unit is a complex unit to design due to space constraints there is less space available & have to adjust all the parts in available space. It consists of a dump cylinder to operate clamping & unclamping car panels.
Que 19th Ans:-
Slide units are positioning units that are used to position the fixtures, weld gun, units, robots into position for further operations. slider units are most commonly used where there is the actuation in the specific direction is not possible