Fixture is a kind of process equipment for clamping workpieces, which is widely used in machining, heat treatment, assembly, welding and testing in the process of mechanical manufacturing. Fixtures used on metal cutting machine tools are collectively referred to as machine tool fixtures. Shown today is a quick fixture, a fixture from Japan's Imao.

Machine tool fixtures can be divided into five categories: general fixtures, special fixtures, adjustable fixtures, combined fixtures and assembled fixtures.

1. Universal fixture

The standardized fixtures that can process different workpieces within a certain range are called universal fixtures. Their structure and size have been standardized, and they have a certain degree of versatility, such as three-jaw self-centering chucks, flat-mouth vices for machine tools, four-jaw single clamps. Moving chuck, bench vice, universal indexing head, top, center frame and magnetic table, etc. These clamps are highly adaptable and can be used to clamp a variety of workpieces within a range of shapes and sizes. These fixtures are factory-built and supplied as machine tool accessories, and can be purchased as an option. The disadvantage is that the accuracy of the fixture is not high, the productivity is also low, and it is difficult to clamp workpieces with complex shapes, so it is generally suitable for single-piece small batch production.

2. Adjustable clamps

Some components can be adjusted or replaced to accommodate a variety of workpiece processing fixtures, called adjustable fixtures. Adjustable jig is a new type of jig developed for the defects of general jig and special jig. For workpieces of different types and sizes, it is only necessary to adjust or replace the individual positioning elements and clamping elements on the original fixture. It can generally be divided into general adjustable clamps and group clamps. The general scope of the former is larger than that of general fixtures; the latter is a special adjustable fixture, which is designed according to the principle of grouping and can process a family of similar workpieces, so it is better used in multi-variety, medium and small batch production. economic effect.

3. Combination fixture

A fixture assembled for a certain process of a workpiece using standard combination components and parts is called a combination fixture. The combination jig is a modular jig. The standard modular elements have high precision and wear resistance and can be assembled into various fixtures. The fixture can be disassembled after use, and left to assemble a new fixture after cleaning. Since the use of the combined fixture can shorten the production preparation cycle, the components can be used repeatedly, and has the advantages of reducing the number of special fixtures, etc., the combined fixture is a more economical method in single-piece, medium and small batch production and CNC machining. fixture.

4. Special fixture

A fixture designed and manufactured for a certain process of a workpiece is called a special fixture. In the production of relatively stable products and large batches, various special fixtures are used to obtain higher productivity and processing accuracy. The design cycle of the special fixture is longer and the investment is larger. Special fixtures are generally used in mass production. In addition to mass production, some special fixtures also need to be used in small and medium batch production, but specific technical and economic analysis should be carried out in structural design.

5. Assembly jig

The jig assembled with special standardized and serialized assembly parts is called an assembly jig. It has the advantages of the combined fixture, but it has higher precision, higher efficiency and compact structure than the combined fixture. It often has small hydraulic cylinders in its base plate and clamping parts. Such fixtures are more suitable for use on CNC machine tools.