Workpiece fixturing requirements as jigs and fixtures , the first to meet the mechanical processing. Meanwhile , CNC machining fixture as well as its own characteristics . These features are:
CNC machining for varieties , small batch production , in order to clamping of different sizes , different shapes of many varieties of the workpiece , CNC machining fixture should have a flexible , can be adjusted through a variety of shapes and sizes clamping workpieces .
Traditional dedicated fixture with positioning , clamping , guide and four functions of the knife , and CNC machine tools are generally equipped with a touch test probe , tool presetting and parts and other equipment on the knife , the knife can solve the problem by machine . CNC machine tools by the precise positioning accuracy process control can be realized fixture tool oriented features . So NC machining fixture orientation and generally do not need the knife functions only requires a positioning and clamping function can meet the requirements , which simplifies fixture construction.
In order to meet the high efficiency of CNC machining , CNC machining fixtures should be possible to use pneumatic, hydraulic, electric and other fast automatic clamping device clamped to shorten the auxiliary time .
Fixture itself should have sufficient rigidity to accommodate the large amount of cutting cutting . CNC machining processes has focused features in a workpiece clamping of the cutting force is necessary to carry out a lot of rough , but also to carry out the work to achieve the ultimate precision finishing , so the fixture rigidity and clamping force must meet the large cutting force requirements.
In order to meet various CNC machining , to avoid fixture clamp structure includes the components of the tool path interference , multi- tool fixture structure do not interfere with the processing of the various parts of the surface of the workpiece.
Positioning fixture to reliable positioning element should have a high positioning accuracy , the site should be easy to locate clear debris, no chips accumulates . Such as locating surface of the workpiece is small , consider the creation process bosses or auxiliary reference . The small rigidity of the workpiece, the clamp should ensure minimal deformation, such as a point near the support point of the clamp , the clamping force to avoid the hollow region of the workpiece and the like . When completed with roughing and finishing in one step , if these measures can not be controlled within the range of deformation of the workpiece machining accuracy requirements shall be suspended before finishing the program , allowing the operator to pre- conversion after finishing in the rough clamping force ( appropriately reduced ) to reduce clamping deformation on machining accuracy .
