The fixture of the hottest milling machine

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Fixture of milling machine

1. basic requirements

generally, complex fixture is not required in NC milling, only simple positioning and clamping are required. Its design principle is also the same as that of general milling machine fixture. Combined with the characteristics of NC milling, some basic requirements are put forward here:

· to ensure that all the surfaces to be machined in this process are fully exposed, The fixture should be as open as possible, because a certain calibration distance of 5 points should be maintained between the clamping mechanism elements and the machining surface. At the same time, the clamping mechanism elements are required to be as low as possible to prevent interference between the fixture and the milling machine spindle sleeve, tool sleeve and cutting tool during machining

· in order to keep the installation orientation of the parts consistent with the direction of the machine tool coordinate system and the programming coordinate system, the fixture shall ensure the directional installation on the machine tool, and it is also required to coordinate the positioning surface of the parts to maintain a certain coordinate relationship with the machine tool

· the fixture has good rigidity and stability. Try not to use the design of replacing the clamping point during the processing. When the clamping point must be replaced during the processing, pay special attention not to damage the positioning accuracy of the fixture or workpiece due to the replacement of the clamping point

2. types of common fixtures

there are generally the following types of fixtures commonly used in NC Milling:

· universal combined fixture. It is suitable for small and medium-sized workpieces in small batch production or development to be milled on a CNC milling machine

· special milling fixture. This is a fixture specially designed and manufactured for one or several similar workpieces. It is generally used when the annual output is large or when it is necessary to develop. Its structure is fixed and can only be used in the specific process of a specific part. The design of this kind of fixture should be simplified to shorten the manufacturing time as much as possible

· multi station fixture. Multiple workpieces can be clamped at the same time, which can reduce the number of tool changes. It is convenient to process and stabilize the industrial investment to load and unload workpieces at the same time, which is conducive to shortening the auxiliary time and improving the productivity. It is more suitable for medium batch production

· pneumatic or hydraulic fixture. It is suitable for the production of large quantities of workpieces. The use of other fixtures is particularly laborious and laborious. Driving the control valve of the hydraulic system can reduce the labor intensity of workers and improve productivity. However, such fixtures have complex structures, high costs and long manufacturing cycles

· universal milling fixture. There are universal adjustable fixtures, vice, dividing head and three jaw chuck, etc

3. selection principle of NC milling machine fixture

when selecting fixtures, it is usually necessary to consider the production batch, production efficiency, quality assurance and economy of the product. The following principles can be referred to when selecting:

· when the production volume is small or the development is carried out, universal combined fixtures should be widely used, which marks that Jin min's scientific research strength has reached a new height. Other fixtures should be considered only when the combined fixtures cannot be solved

· special fixture can be considered for small batch or batch production, but it should be as simple as possible

· multi station fixture, pneumatic and hydraulic fixture can be considered for large production batch. (end)

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