1, which meets the stability and reliability of workpiece positioning during use;

2, there is enough bearing or clamping strength to ensure the machining process of the workpiece on the fixture;

3, simple and quick operation in the clamping process is satisfied;

4. Wearable parts must be of a structure that can be quickly replaced, and it is best not to use other tools under sufficient conditions;

5, meet the reliability of fixture repeated positioning during adjustment or replacement;

6. Avoid complicated structure and high cost as much as possible;

7, as far as possible, choose standard parts as parts;

8. Form the systematization and standardization of internal products of the company.

Second, the basic methods and steps of fixture design

(1) Design notice, finished parts drawing, blank drawing, process route and other technical data, so as to know the processing technical requirements, positioning and clamping scheme, processing contents of the previous process, blank situation, machine tools, tools, inspection measuring tools, machining allowance and cutting consumption of each process;

(2) Understand the production batch and the demand for fixtures;

(3) Understand the main technical parameters, performance, specifications and accuracy of the machine tool used, as well as the contact size of the structure connected with the fixture;

(4) Standard material inventory of fixture.

Extended data

Whether the fixture design is reasonable or not directly affects the quality, production efficiency and processing cost of the workpiece. In actual production, the design of fixture is mainly based on the processing scheme and the experience of operators. It is necessary to minimize the number of clamping, reduce the frequency of tool changing, complete multiple processes at one time, save auxiliary time and improve production efficiency.

Generally speaking, the commonly used fixtures in CNC milling are as follows:

Universal combined fixture. Suitable for small batch production or developing and milling small and medium-sized workpieces on CNC milling machines.

Special milling fixture. This fixture is specially designed and manufactured for one or several similar workpieces, and is generally used when the annual output is large or it is necessary to develop. Its structure is fixed and it is only used in the specific process of specific parts. The design of this fixture should be simplified and the manufacturing time should be shortened as much as possible.

Multi-station fixture. Multiple workpieces can be clamped at the same time, reducing the number of tool changes. It is convenient to process and load and unload workpieces at the same time, which is beneficial to shorten the auxiliary time and improve the productivity, and is more suitable for medium-batch production.

Pneumatic or hydraulic clamp. Suitable for large-scale production occasions, the use of other fixtures is particularly labor-intensive, which can reduce the labor intensity of workers and improve productivity. However, this fixture has complex structure, high cost and long manufacturing cycle.

Universal milling fixture. There are universal adjustable fixtures, vice, indexing head and three-jaw chuck.