introduction
The ideal machining program should not only ensure the production of qualified workpieces that conform to the drawings, but also enable the function of the CNC machine tools to be properly applied and fully utilized. CNC machine tool is a high-efficiency automation equipment, its efficiency is 2 to 3 times higher than that of ordinary machine tools. To fully utilize this feature of CNC machine tools, the workpiece must be processed before programming, and the economy should be selected according to specific conditions. A reasonable process plan. The inconsistency of CNC Machining process is an important factor affecting the processing quality, production efficiency and processing cost of CNC machine tools. This paper starts from the production practice, discusses and summarizes some process problems in the CNC turning process.
1 Division of CNC machining operations
Processing parts on CNC machine tools, the process is relatively concentrated, one assembly should complete all the steps as much as possible, the common process division principle has the following two.
Guaranteed accuracy principle
CNC machining has the conditions of concentrated processes. The roughing and finishing are often done in one clamping to ensure the machining accuracy of the parts. When the thermal deformation and the cutting force deformation have a great influence on the machining accuracy of the parts, coarse and fine machining should be carried out. Take it apart.
Principle of improving production efficiency
In CNC machining, in order to reduce the number of tool changes and save the tool change time, the machining parts that need to be processed by the same tool should be completed, and then another tool is used to process other parts. At the same time, the air travel should be minimized. When using the same tool to machine multiple parts of the workpiece, the shortest route should be used to reach each machining part.
In actual production, CNC machining often divides the process according to the tool or the machining surface.
2 selection of tool location
In CNC machining, the NC program should describe the trajectory of the tool relative to the workpiece. In CNC turning, the formation of the workpiece surface depends on the position and shape of the moving blade envelope, but in programming, it is only necessary to describe the trajectory of a selected point on the tool system. The tool position of the tool is the point at the tool that is selected on the tool to represent the position of the tool. The machining path described by the program is the motion track of the point.
In CNC turning, theoretically, any point on the tool can be selected as the tool position, but in order to facilitate programming and ensure machining accuracy, the choice of tool position has certain requirements and skills. In CNC machining, the selection of the tool point generally follows the following rules: the end mill should be the intersection of the tool axis and the tool bottom: the ball end milling cutter is the ball center: the drill bit should be the drill tip: the turning tool should be a hypothesis At the tip or tip arc center, the tool knives should be selected when selecting:
Select the point on the tool that can be directly measured. The measurement point when the tool point is pre-adjusted with the tool length should be as consistent as possible:
Where possible, the tool location should be directly related to the size of the more demanding or the size that is difficult to measure:
The selected tool position enables the tool limit position to be directly reflected in the program's motion command:
Programmers should have a customary tool location selection method, which should not be changed:
The selected tool location should be graphically indicated in the tool adjustment diagram.
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