Design of Welding Fixture for Automobile Mould Manufacturers

1. Automobile mould manufacturers' design requirements for body welding fixtures

(1) For body parts and assemblies that should be interchangeable after stamping parts assembly and welding, all matching parts of the body should be used, especially the shape and size of the holes meet the technical requirements.

(2) Assembly, positioning and clamping can be carried out quickly and accurately, and the welding parts should be easy to operate. After the clamping mechanism is released, the weldment can be easily taken out from the fixture, which is safe and reliable.

(3) When designing the fixture, attention should be paid to the conduction and insulation of some parts on the fixture to improve the assembly and welding quality of the body.

(4) Due to the complex structure of the vehicle body, the design of positioning parts and clamping parts should fully consider the generalization and standardization of processing technology and parts, so as to facilitate the replacement of wearing parts and restore the original design accuracy.

(5) The assembly and welding fixtures of the body assembly are complex and heavy, and often need to be adjusted and corrected by adjusting the sample holder during manufacture and use.

2. Selection of assembly and welding positioning benchmarks for automobile mould manufacturers

When the workpiece is clamped, the datum used to make the workpiece occupy the correct position in the middle of the fixture is called the positioning datum. The correct choice of positioning reference will directly affect the assembly accuracy of the workpiece.

3. Positioning methods and elements of auto mold manufacturers

The main clamping object of automobile body assembly and welding fixtures for automobile mould manufacturers is stamping parts. Due to the complex manufacturing shape and easy deformation, the fixture design should consider the positioning of the curved surface shape, the platform shape on the curved surface, the steps formed by the stretching and bending of the workpiece, the trimming window and outer edges, mounting holes and process holes.

Due to the complex shape of the stamping part, it is in direct contact with the positioning element during the clamping process, which determines the special shape of the positioning element. The selected targeting features are as follows:

(1) Locating pin: Locating pin positioning is the positioning method adopted by the welding fixture in the normal assembly. The cab bottom plate reinforcement beam is thicker and more rigid, which can be regarded as rigid assembly. The suspension holes on the base plate can be positioned with two cylindrical pins. 

(2) Positioning block: The door opening of the cab and the front and rear windshields are positioned by the positioning block on the positioning body. The positioning block and the body are designed separately, which avoids the entire profiling process and makes the manufacturing and adjustment of the positioning parts very simple and convenient.

(3) Semi-circular block: In general, cylindrical workpieces are positioned with V-shaped blocks. However, when the positioning elements in the welding fixture need to conduct electricity at the same time, or when the thickness of the workpiece tube wall is less than 0.5D (D is the diameter of the workpiece), in order to prevent the clamping deformation of the workpiece, semicircular blocks are often used for positioning. The minimum diameter of the semicircle block hole shall be the maximum diameter of the workpiece positioning datum axis.

(4) Surface positioning plate.