Determine the cutting route and arrange the processing sequence
The tool path is the motion path of the tool in the whole machining process. It not only includes the content of the work step, but also reflects the order of the work step. The cutting route is one of the bases for programming. Pay attention to the following points when determining the cutting route:
1. Seeking the shortest processing route: reducing the empty tool time can save nearly twice the positioning time and improve the processing efficiency.
2. The final contour is finished in one cutting: in order to ensure the roughness requirements of the workpiece contour surface after machining, the final contour should be arranged to be processed continuously in the last cutting.
3. Select the cutting in and cutting out direction: when considering the cutting in and cutting out (cutting in and cutting out) route of the tool, the cutting out or cutting in point of the tool should be on the tangent along the contour of the part to ensure the smooth contour of the workpiece; Avoid scratching the workpiece surface by vertically cutting up and down on the contour surface of the workpiece; Try to reduce the pause during contour machining (elastic deformation caused by sudden change of cutting force) to avoid leaving knife marks.
4. Select the route to make the workpiece deform less after machining: for slender parts or thin plate parts with small cross-sectional area, the cutting route should be arranged by several times of cutting to the final size or by symmetrically removing the allowance. When arranging the work steps, the work steps with less damage to the rigidity of the workpiece should be arranged first.
2、 Determine positioning and clamping scheme
The following problems should be paid attention to when determining the positioning and clamping scheme:
(1) Try to unify the design basis, process basis and programming calculation basis;
(2) Concentrate the process as much as possible, reduce the clamping times, and try to process all the surfaces to be processed after one clamping;
(3) Avoid using the clamping scheme with long manual adjustment time;
(4) The action point of the clamping force should fall on the part with good rigidity of the workpiece.
3、 Determine the relative position of the tool and the workpiece
For CNC machine tools, it is very important to determine the relative position between the tool and the workpiece at the beginning of processing. This relative position is achieved by confirming the tool setting point. Tool setting point refers to the reference point that determines the relative position of the tool and the workpiece through tool setting. The tool setting point can be set on the machined part or at a certain position on the fixture that has a certain size connection with the part positioning benchmark. The tool setting point is often selected at the machining origin of the part.
The selection of tool setting points should follow the following principles:
(1) The selected tool setting point should make programming simple;
(2) The tool setting point should be located at a position that is easy to align and determine the machining origin of parts;
(3) The tool setting point should be selected at a convenient and reliable position for inspection during processing;
(4) The selection of tool setting points should be conducive to improving the machining accuracy.
4、 Determine the cutting amount
For high-efficiency metal cutting machine tools, the processed materials, cutting tools and cutting parameters are the three major elements. These conditions determine the processing time, tool life and processing quality. Economic and effective machining methods require reasonable selection of cutting conditions.