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Features of machine fixtures


First to meet the mechanical processing of the workpiec […]

First to meet the mechanical processing of the workpiece when the clamping requirements. At the same time, CNC machining fixture also has its own characteristics. These features are:
(1) CNC machining for multi-species, small and medium-volume production, in order to be able to clamp different sizes, different shapes of multi-species of the workpiece, CNC machining fixture should be flexible, with appropriate adjustments to hold a variety of shapes and sizes of the workpiece .
(2) the traditional special fixture with positioning, clamping, guidance and tooling four functions, and CNC machine tools are generally equipped with a contact test head, tool presetter and knife parts and other equipment, can be resolved by the machine Knife problem. The precise positioning accuracy of the NC machine tool controlled by the program can realize the tool orientation function in the fixture. So the NC machining fixture generally do not need to guide and knife function, only requires a positioning and clamping function, will be able to meet the requirements, so that the structure can simplify the fixture.
(3) In order to adapt to the high efficiency of CNC machining, CNC machining fixture should be used as far as possible the use of pneumatic, hydraulic, electric and other automatic clamping device fast clamping to shorten the auxiliary time.
(4) The fixture itself should have sufficient rigidity to accommodate large cuttings. CNC machining has the characteristics of the process, in the workpiece of a fixture is necessary to carry out a large rough cutting, but also to achieve the final accuracy requirements of the workpiece finishing, so the fixture stiffness and clamping force to meet the large Cutting force requirements.
(5) In order to meet the numerical control processing, to avoid the fixture structure, including the fixture on the tool movement trajectory of the interference, fixture structure do not interfere with the workpiece on the workpiece parts of the multi-side processing.
(6) fixture positioning should be reliable, positioning components should have a high positioning accuracy, positioning site should be easy to chip, no chip accumulation. If the positioning surface of the workpiece is too small, consider adding a process boss or auxiliary reference.
(7) for small stiffness of the workpiece, should ensure that the minimum clamping deformation, such as the clamping point near the support point, to avoid the clamping force on the workpiece in the hollow area. When roughing and finishing are completed in one step, if the above measures can not control the deformation of the workpiece within the range of machining accuracy, the program should be suspended before finishing, allowing the operator to transform before finishing the rough Clamping force (appropriate to reduce) to reduce the impact of clamping deformation on the machining accuracy.