CNC machining process design

The process design of CNC machining must be considered comprehensively, paying attention to the correct division of the process, the reasonable arrangement of the sequence and the connection between the NC machining process and the ordinary process.

1. CNC machine is divided <br> <br> compared with ordinary machining step, more concentrated processing step, according to the processing characteristics of CNC machine tools, the division processing step are the following ways:

1) According to the clamping positioning division process This method is generally adapted to the workpiece with a small amount of processing, mainly by dividing the processing part into several parts, and processing each part in each process. For example, when machining the shape, it is clamped in the inner cavity; when the inner cavity is machined, it is clamped in the shape.

2) According to the tool division process, in order to reduce the number of tool changes and the idle time, you can use the principle of tool concentration to divide the process, use a knife to complete all the machining parts that can be processed in one setup, and then change the second knife. , processing other parts. This method is mostly used in special CNC machine tools or machining centers.

3) Dividing the parts that are easy to produce deformation by rough and fine machining. Considering the processing precision and deformation of the workpiece, the process can be divided according to the principle of coarse and fine machining, that is, coarse and fine.

In the division of the process, it is necessary to be flexible according to the structural requirements of the workpiece, the way the workpiece is mounted, the processing technology of the workpiece, the performance of the CNC machine tool, and the organization and management of the factory.

2. Arrangement <br> <br> processing sequence processing sequence should be arranged according to the structure and condition of the blank workpiece, workpiece positioning and mounting selecting and focusing on the rigidity of the workpiece is not destroyed, to minimize the deformation, so the processing sequence arrangement The following principles should be followed:

1) The processing of the previous process can not affect the positioning and clamping of the next process. 2) The outer contour of the workpiece after machining the inner cavity of the workpiece. 3) Minimize the number of repeated positioning and tool change. 4) Multi-process in one installation and processing In the middle, the process of less rigid damage to the workpiece is arranged first.

Step 3. ordinary NC machining step due to the convergence <br> <br> NC machining step interspersed among the entire workpiece machining process, the procedures required to establish mutual status request, such as the allowance of reservation, positioning surface With the accuracy of the hole and the tolerance of the shape and position, the technical requirements of the orthopedic process, the heat treatment of the blank, etc., each process must be considered comprehensively.

4. The main task of CNC machining step and the processing route design <br> <br> design CNC machining step: a step of determining the specific process contents, cutting parameters, process equipment, installation and positioning of the tool trajectory, is programmed Be prepared. The setting of the machining route is a very important link. The machining route is the movement track of the tool point relative to the workpiece during the cutting process. It not only includes the content of the machining process, but also reflects the arrangement of the machining sequence. Therefore, the machining route is An important basis for writing machining programs.

1) Principle 1 for determining the machining route The machining route should ensure the accuracy and surface roughness of the workpiece to be machined.

2 Design the processing route to reduce the idle travel time and improve the processing efficiency.

3 Simplify numerical calculations and reduce blocks to reduce programming effort.

4 Determine the number of cycle machining according to the shape, stiffness, machining allowance, and rigidity of the machine tool system.

5 Reasonably design the cutting and cutting direction of the tool. The unidirectional approach positioning method is adopted to avoid the positioning error caused by the backlash of the transmission system.

6 Reasonable selection of milling or up-cut milling in milling. Generally speaking, CNC machine tools use ball screws with small movement clearance, so the advantage of down-cut milling is more than that of up-cut milling.

2) CNC machine tool processing route 1 CNC lathe machining route CNC lathe turning end machining path shown in Figure 1 AB-0p-D, where A is the tool change point, B is the point of entry, C-0p is the tool cutting path, 0p is Cut out the point, D is the retraction point.

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