If you want to improve the technology of CNC machining, you must first understand the content of the process design of CNC machining, broaden the depth and breadth of the thinking mode of researchers, and take into account every factor that may cause loopholes when programming CNC machining. Only in this way can the work efficiency of CNC machining be guaranteed.
1. Arrangement of CNC machining sequence
The arrangement of the CNC machining sequence should be based on the structure of the workpiece and the status of the blank, select the positioning and installation method of the workpiece, and focus on ensuring that the rigidity of the workpiece is not damaged and minimize deformation. Therefore, the arrangement of the CNC machining sequence should follow the following principles:
1) The CNC machining of the previous process cannot affect the positioning and clamping of the next process
2) First CNC machine the inner cavity of the workpiece and then CNC machine the outer contour of the workpiece
3) Minimize the number of repeated positioning and tool changes
4) Among the multiple processes of CNC machining at one time, arrange the process with less rigid damage to the workpiece first.
2. Division of process
Compared with the CNC machining of ordinary machine tools, the CNC machining process is more concentrated. According to the CNC machining characteristics of the CNC machine tool, the CNC machining process can be divided in the following ways:
1) Divide the process according to the clamping and positioning
This method is generally suitable for workpieces with little CNC machining content. It mainly divides the CNC machining parts into several parts, and CNC processes one part of each process. For example, when CNC machining the shape, it is clamped with the inner cavity; when CNC is machining the inner cavity, it is clamped with the shape.
2) Divide the process according to the tools used
In order to reduce the number of tool changes and idle time, the principle of tool concentration can be used to divide the process. In one clamping, one tool can be used to complete all CNC machining parts that can be processed by CNC, and then the second tool can be used to CNC process other parts. . This method is mostly used on special CNC machine tools or CNC machining centers.
3) Divide the process by rough and fine CNC machining
For parts that are prone to CNC machining deformation, considering the CNC machining accuracy and deformation of the workpiece, the process can be divided according to the principle of separating rough and fine CNC machining, that is, rough first and then fine.
In the division of the process, it should be flexibly grasped according to the structural requirements of the workpiece, the installation method of the workpiece, the CNC machining process of the workpiece, the performance of the CNC machine tool, and the factory production organization and management, and strive to be reasonable.
3. Design of CNC machining procedures and CNC machining routes for CNC machine tools
The main task of the CNC machining process design of the CNC machine tool: to determine the specific CNC machining content, cutting amount, process equipment, positioning and installation method, and tool movement trajectory of the process, so as to prepare for the programming. Among them, the setting of the CNC machining route is a very important link. The CNC machining route is the movement track of the tool position relative to the workpiece during the cutting of the CNC machining process. It not only includes the content of the CNC machining process, but also reflects the arrangement of the CNC machining sequence. , so the CNC machining route is an important basis for writing CNC machining programs.
1) Determine the principle of CNC machining route
① The CNC machining route should ensure the accuracy and surface roughness of the CNC-machined workpiece.
② The design of CNC machining routes should reduce idle travel time and improve CNC machining efficiency.
③ Simplify numerical calculation and reduce program segments, reducing programming workload.
④ According to the shape, stiffness, CNC machining allowance, stiffness of the machine tool system, etc. of the workpiece, determine the number of CNC machining cycles.
⑤ Reasonably design the cutting-in and cutting-out directions of the tool. The one-way approach positioning method is adopted to avoid the positioning error caused by the backlash of the transmission system.
⑥ Reasonable selection of down milling or up milling in milling CNC machining. Generally speaking, CNC machine tools use ball screws with small movement gaps, so down milling has more advantages than up milling.
2) CNC machining route of CNC machine tools
3) CNC machining route for turning end face of CNC lathe
4. The connection between CNC machining process and ordinary process
Since the CNC machining process is interspersed in the entire process of the CNC machining of the workpiece, each process needs to establish state requirements for each other, such as the reservation of the CNC machining allowance, the accuracy and shape tolerance requirements of the positioning surface and the hole, and the orthopedic process. Technical requirements, heat treatment of blanks and other requirements, each process must be considered comprehensively
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