There are several common methods for cnc to clamp workpieces:
1, vise direct clamping: This clamping method is the simplest, most convenient and most economical clamping method in NC milling. In order to make the positioning datum coincide with the design datum and process datum, the soft jaws should be roughly milled and finely milled before machining, so as to ensure the parallelism of the two jaws to one axis of the machine tool and the verticality to the other two axes of the machine tool. The precision of positioning datum is high, and the positioning error is far less than the requirements of the part itself, so that the part will not be out of tolerance because of the vice problem. This clamping method needs less auxiliary time, is convenient to clamp, saves the manufacturing cost and time of the fixture, and is widely used in small batch production and single-piece trial production.
2. Pressing and clamping of pressure plate: This clamping method is the most commonly used clamping method in NC milling. Because the clamping force generated by the direct clamping of the vice is relatively large, the parts are deformed. Even by adjusting the clamping force, the deformation problem cannot be avoided. This clamping method has the advantages of low manufacturing cost, short cycle and simple structure. However, this clamping method takes a long time, and the parts need to be clamped twice, so it is skillful and the clamping force should be appropriate to prevent the parts from being deformed.
3. Fixture clamping: It is a common clamping method for complex parts. This fixture has high manufacturing cost, long tooling cycle and complex structure, but this clamping method has short clamping time, reliable and convenient clamping, and is suitable for mass production of parts.
4, vice and V-block clamping: generally used for small parts, the overall size is below 15mm, due to the small size of the parts, the above three methods can not be used for clamping, multi-process processing is carried out on the ordinary milling machine, all the processing contents of the parts are clamped on the CNC machine tool at one time, and then the parts are cut off with a saw blade.
The requirements for NC clamping workpieces are as follows:
1, the clamping device should not affect the feed, and the machined parts should be open.
2, must ensure the minimum clamping deformation, ensure the accuracy of parts.
3. Convenient loading and unloading, and the auxiliary time is as short as possible. If conditions permit, pneumatic and hydraulic jigs or multi-station jigs should be used for large batch parts.
4. For small parts or parts with short processing time, consider clamping several parts or dozens of parts at the same time on the workbench for processing. To improve efficiency.
5. The fixture structure should be as simple as possible to reduce the fixture manufacturing cost. When the processing batch of parts is small, try to use general fixtures such as combined fixtures and adjustable fixtures; Special fixture should be considered in mass production of parts, but the cost can be reduced.