The fixture first appeared in the late 18th century. With the continuous advancement of science and technology, fixtures have evolved from an auxiliary tool to a complete range of process equipment. 1. Current status of machine tool fixtures According to statistics from the International Association for Production Research, the number of workpieces produced in medium and small batches has accounted for about 85% of the total number of workpieces. Modern production requires that the varieties of products manufactured by enterprises are frequently updated to meet the needs and competition of the market. However, the average company is still accustomed to using a large number of traditional special fixtures. Generally, in a medium-capacity factory, there are thousands or even nearly 10,000 sets of special fixtures. On the other hand, in a multi-variety production enterprise, every In 3~4 years, about 50~80% of special fixtures will be updated, and the actual wear of the fixture is only about 10~20%. Especially in recent years, the application of new machining technologies such as CNC machine tools, machining centers, group technology, and flexible manufacturing systems (FMS) has put forward the following new requirements for machine tool fixtures: 1) It can quickly and conveniently equip new products for production, in order to shorten the production preparation cycle and reduce production costs; 2) can clamp a set of workpieces with similar characteristics; 3) High-precision machine tool fixtures that can be applied to precision machining; 4) New machine tool fixtures that can be applied to various modern manufacturing technologies; 5) Adopt high-efficiency clamping device with hydraulic station and other power sources to further reduce labor intensity and increase labor productivity; 6) Improve the standardization of machine tool fixtures. 2. The development direction of modern machine tool fixtures The development direction of modern machine tool fixtures mainly includes four aspects: standardization, precision, high efficiency and flexibility. (1) The standardization and generalization of standardized machine tool fixtures are two aspects of interconnection. At present, China has the national standards for fixture parts and components: GB/T2148~T2259-91 and various general fixtures and combination fixture standards. The standardization of machine tool fixtures is conducive to the commercial production of fixtures, which is conducive to shortening the production preparation cycle and reducing the total production cost. (2) Precision With the increasing accuracy of mechanical products, it is bound to improve the accuracy requirements of fixtures. There are many types of precision fixtures, such as multi-toothed discs for precision indexing, which have an indexing accuracy of ±0.1"; high-precision three-jaw self-centering chucks for precision turning with a centering accuracy of 5 μm . (3) Efficient and efficient fixtures are mainly used to reduce the basic time and auxiliary time of workpiece processing to improve labor productivity and reduce labor intensity of workers. Common high-efficiency clamps include automated fixtures, high-speed fixtures, and fixtures with clamping devices. For example, using an electric vise to clamp a workpiece on a milling machine can increase the efficiency by about 5 times; using a high-speed three-jaw self-centering chuck on a lathe ensures that the jaws are still strong at a test speed of 9000 r/min. The workpiece is clamped to the ground so that the cutting speed is greatly improved. At present, in addition to the corresponding high-efficiency and automatic fixtures in the production line and automatic line configuration, various automatic clamping workpiece holders and automatic fixture changing devices have appeared on CNC machine tools, especially in the machining center, giving full play to the numerical control machine tools. effectiveness. (4) The flexibility of the flexible machine tool fixture is similar to the flexibility of the machine tool. It refers to the ability of the machine tool fixture to adapt to the variable factors of the process by adjusting and combining. The main variables of the process are: process characteristics, production batch, shape and size of the workpiece. The new types of fixtures with flexible features include: combination fixtures, universal adjustable fixtures, group fixtures, modular fixtures, and CNC fixtures. In order to meet the needs of modern machinery industry multi-variety, small and medium-sized batch production, expand the degree of flexibility of the fixture, change the non-removable structure of the special fixture to a detachable structure, and develop an adjustable fixture structure, which will be the main direction of the current fixture development. Expansion Joint Covers,Expansion Joint,Expansion Joint System Flooring Accessories,Stair Parts Co., Ltd. , http://www.chaluminumprofile.com