When positioning holes processed by workpiece pretreatment, it is necessary to use pins with tolerance for positioning. By matching the accuracy of workpiece hole with the accuracy of pin shape and combining them according to the matching tolerance, the positioning accuracy can meet the actual demand.
In addition, when positioning with pins, one usually uses a straight pin and the other uses a diamond pin, which makes it more convenient to load and unload the workpiece, and it is rare for the workpiece and the pin to get stuck.
Extended data:
basic requirement
1. The key to ensure the machining accuracy of the workpiece is to correctly select the positioning datum, positioning method and positioning element, analyze the positioning error when necessary, and the influence of the structure of other parts in the fixture on the machining accuracy, so as to ensure that the fixture can meet the machining accuracy requirements of the workpiece.
2. To improve the production efficiency, the complexity of the special fixture should be adapted to the production capacity, and various fast and efficient clamping mechanisms should be adopted as far as possible to ensure convenient operation, shorten the auxiliary time and improve the production efficiency.
3. The structure of special fixture with good technological performance should be simple and reasonable, which is convenient for manufacturing, assembly, adjustment, inspection and maintenance.
4, good performance fixture should have enough strength and stiffness, operation should be simple, labor-saving, safe and reliable. On the premise of objective conditions and economy, pneumatic, hydraulic and other mechanical clamping devices should be used as far as possible to reduce the labor intensity of operators.
5. The special fixture with good economy should adopt standard parts and structures as far as possible, and strive for simple structure and easy manufacturing to reduce the manufacturing cost of the fixture. Therefore, in the design, the necessary technical and economic analysis should be carried out on the fixture scheme according to the order and production capacity, so as to improve the economic benefits of the fixture in production.