Introduction to Automotive Body-in-White (BIW) Fixture Design - Chapter 2
Welcome to the fascinating world of automotive engineering! Today, we're diving into the essential aspects of Body-in-White (BIW) fixture design. Whether you're a budding engineer or just curious about how cars are put together, this guide is for you.
What is Body-in-White (BIW)?
In the automotive industry, the term Body-in-White (BIW) refers to the stage in car manufacturing where the vehicle's sheet metal components are welded together. This stage is crucial as it forms the car's structural foundation before it moves on to painting and the assembly of other parts. BIW fixture design involves creating the tools that hold, support, and position these body parts during welding and assembly.
Types of Fixtures in BIW
Fixtures are specialized tools that ensure car parts are held securely and precisely during manufacturing. Here's a breakdown of the main types of fixtures used in BIW:
1. Welding Fixtures
These fixtures hold the components in place during various welding processes:
- Spot Welding
- MIG Welding
- Fastener Welding
- Laser Welding
- These can be further classified into geo and respot welding fixtures.
2. Assembly Fixtures
These fixtures ensure that parts are aligned correctly during assembly.
3. Checking Fixtures
Used to inspect the dimensions and geometry of the assembled components.
4. Transport Fixtures
These facilitate the movement of parts between different stages of manufacturing.
The 3-2-1 Principle: Everyone's Favorite
The 3-2-1 principle is a fundamental concept in fixture design. It helps define the location and orientation of a workpiece in space, ensuring it is fully constrained and stable. Here's how it works:
- 3 points establish a plane.
- 2 points establish a line perpendicular to the plane.
- 1 point establishes the final location in the third dimension.
Diamond Pin and Round Pin
Diamond Pin
- Purpose: Locates a part in two directions (X and Y axes).
- Benefit: Allows for thermal expansion without binding the part.
Round Pin
- Purpose: Locates a part in one direction (X or Y axis).
- Benefit: Provides precise positioning.
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The Importance of CAR-LINE
The CAR-LINE is an imaginary line that runs through the center of the vehicle's body. It serves as a reference for aligning and positioning different body components. This line ensures that all parts are symmetrically assembled around the central axis, maintaining the vehicle's structural integrity and aesthetics.
PLP Points: Your Critical Reference Points
PLP (Primary Locating Points) are strategically chosen to ensure the accurate positioning of car body parts during assembly. These points control the position and orientation of components in all three dimensions, providing the best stability and alignment.
Introduction to Standard Parts
Standard parts are essential in fixture design, providing consistency and efficiency. Here are some key components:
- Risers: Elevate and support fixture components.
- Cylinders: Pneumatic or hydraulic components that apply clamping force.
- L-Block: Provides rigid support and alignment.
- Pins: Used for accurate locating and positioning.
- Base: The foundation of the fixture holding all components together.
Various Design Components
Rest Unit
- Function: Supports the workpiece.
- Components: Base plate, riser, and rest pad.
Clamp Unit
- Function: Holds the workpiece securely.
- Components: Clamp arm, cylinder for actuation, and contact pad.
Location Unit
- Function: Ensures precise positioning using pins or blocks.
- Components: Often includes diamond and round pins for accuracy.
On a different note, regarding I/O blocks, prox blocks, and valve blocks: If you know the number of inputs and outputs, as well as your clamping sequence, you should be able to select or recommend the appropriate components. Always recommend a few extra to accommodate any unexpected change requests from the customer after fabrication or commissioning. This buffer is essential and should be considered universally.
Dive Deeper: Learning Resources
There's a wealth of online resources available to help you learn the basics of BIW fixture design. Many tutorials cover topics such as clamping force and cylinder selection. Additionally, each Original Equipment Manufacturer (OEM) has standard guidelines explaining this process, and cylinder manufacturers provide detailed information with safety margins to consider.
Below are some links created by various gentlemen covering technical details to start your learning journey. Enjoy and happy learning!
BIW Fixture Designer , 3D concept, 2D detailling, Quality control, Team leading ,Catia V5, Siemens Nx ,Fides,Solidworks
5 个月Thanks for sharing