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CNC turning parts processing program characteristics and optimization

The characteristics of CNC turning processing technology are mainly determined from the parts processing positioning benchmark, processing requirements of CNC machining in the blank, the experience of process division of labor, the choice of cutting tools and cutting parameters. For the convenience of understanding, the examples are given based on the actual situation. In addition, it focuses on the optimization methods of CNC programs, including the use of cyclic programs to avoid idling tool paths. Processing process, and application subroutine. By comparing the difference before and after optimization, the superiority of the reasonable scheme is shown. Combined with the actual machining experience, a method to eliminate tool marks and thread burrs in the machining process is provided, and the machining program is given.

At present, the application of CNC cutting technology has entered an unprecedented period of rapid development, is developing in the direction of high speed and efficiency. How to improve the efficiency of CNC machine tools, become a new topic in front of us. The key to improve machining efficiency is to understand the characteristics of NC machining, determine reasonable NC machining technology, select efficient cutting tool and compile reasonable program.

CNC processing technology characteristics

There are similarities and differences between the parts processed by CNC machine tools and those processed by ordinary machine tools. CNC machine tools are processed in strict accordance with the processing program.

The workpiece processed is usually more complex than the workpiece processed by ordinary machine tools. CNC machine tools before processing, must be the machine tool movement process, parts of the processing process, tool shape, cutting amount and tool path into the program, so must determine the correctness of the processing program before programming.

According to practical experience, the process has the following characteristics.

1. Have accurate positioning benchmark.

Batch processing, in order to improve the processing efficiency, generally in the program compilation is completed, the first piece of test cut is completed, no longer change the zero point of the program. Therefore, it is required that the position of each part clamped on the machine must be determined by the machine. The default position is the same as the first article. Therefore, all parts must have the same and accurate positioning reference on the machine tool [3]. For example: turning short bar parts, the benchmark is generally on the end face of the chuck or three claws on the step; For turning slender parts (processing needs to be clamped in the main shaft hole parts), the datum is generally guaranteed by the ladder sleeve; For special parts, it is necessary to find the specific clamping method according to the shape of the part. In short, in the clamping to ensure that the parts in the machine tool Z axis coordinates unchanged.

2. There are certain requirements for blank.

According to the characteristics of CNC processing and positioning, CNC processing of blank shape and size also have certain requirements. The margins of each part of the blank should be as consistent as possible, and the deviation should be kept within 2mm. In this way, in CNC processing, not only can reduce the number of unnecessary empty corridors, improve processing efficiency, but also can avoid collisions, collisions and other accidents.

3. Divide the process by tool.

CNC machining process in addition to following the general principles of technology, but also should consider giving full play to the use of CNC machine tools, and try to focus the process. All processes should be completed at once. Because CNC cutting tools play a pivotal role in CNC machining, is the key to high efficiency of CNC machine tools, so often according to the use of cutting tools to divide the process. A total of 5 tools are needed to process the shown parts, namely, offset tool, external groove tool, end groove tool, external thread tool and drill bit. Machining, the first offset tool set 111, thread diameter 100 and the end step are processed, and then change the tool.

4. The choice of cutting tool and cutting parameters is very important.

The high efficiency of CNC machine tools largely depends on the tool only choose the right tool to give full play to the performance of CNC machine tools. Nowadays, there are many kinds of domestic and imported CNC cutting tools. Large tool companies usually mark the blade brand, applicable materials and cutting parameters on the tool box. First, according to the processing parts; Select the type of blade according to the material and machining parts (such as outer circle, thread and groove), and then select the specific blade according to rough and finish machining. After determining the blade, the corresponding cutting parameters can be determined.

How to optimize the numerical control program

When machining parts on ordinary machine tools, the processing process is usually written on the processing process card. The operator processes the parts according to the "procedure" specified in the process card. Cutting parameters and tool paths are determined by the operator based on experience and regulations. However, in the CNC machine tool processing parts, must be processed parts of all the process and process parameters in the form of code programming input to the machine tool, in order to achieve parts processing. Therefore, the programming work is very important. If the programming is reasonable, it can not only produce high quality parts, but also improve the processing efficiency.

1. Adopt circular scheme

Cycle program is widely used in plane end face, car outer circle, drilling, boring and other programming, greatly simplifying the program structure, reduce the workload of programming, improve the processing efficiency.

2. Avoid idling tool path during machining.

Using a loop in your programming can certainly simplify your program, but it's not always good to use it. When the part shape has steps and the processing allowance is not uniform, in order to avoid idling, generally do not use the cycle program. After rough turning, the second order has a large axial allowance. If using the loop program, will produce a large number of empty passes; If you do not use the cycle program, according to the incoming material, the first two large margin of the step surface for turning, and then the shape of the car will avoid empty, improve processing efficiency. .

3. Application subroutine.

The application of subroutines in the program can simplify the main program, reduce programming workload and improve processing efficiency. Parts of the same series of length and diameter can share a subroutine. For the bottom surface of the inner hole of the part, you can use the following program.

4. Programming method to eliminate knife marks.

When writing CNC program, you can use the tool programming method to eliminate the tool marks with a long diagonal line. In addition to the above method of optimizing the program, there are some other programming techniques, such as applying a delay program before the tool number, adding the program number can call the desired tool at any time, regardless of the tool number. The program.

5. Deburr threads.

The burr of the thread is removed by hand grinding with sandpaper on a general lathe, and the burr is automatically removed by program with a slotting knife on a CNC lathe.

Conclusion

To sum up, CNC machining and ordinary machine processing has many differences. It has its own processing technology characteristics, there are many particularities and shortcuts in programming. Only fully grasp and use them, can really play the high efficiency of CNC machine tools, so that they can better serve us.