Share with you the technical features of ordinary thread of Dalian high-speed CNC vertical lathe

1、 Programming and machining of ordinary thread

In the current CNC lathe, there are generally three machining methods for thread cutting: G32 straight cutting method, G92 straight cutting method and G76 oblique cutting method. Due to different cutting methods and programming methods, the machining errors are also different. We should carefully analyze the operation and use, and strive to process parts with high precision.

1. G32 straight cutting method, because both edges work at the same time, the cutting force is large, and it is difficult to arrange cutting, so the two cutting edges are easy to wear during cutting. When cutting threads with large pitch, due to the large cutting depth and rapid blade wear, the pitch diameter error of the thread is caused; However, its tooth shape accuracy is high, so it is generally used for small pitch thread processing. Because the tool movement and cutting are completed by programming, the machining program is long; As the blade is easy to wear, frequent measurement should be done in processing.

2. G92 straight cutting method simplifies programming and improves efficiency compared with G32 instruction.

3. G76 oblique cutting method, because it is processed with one side edge, the processing edge is easy to be damaged and worn, so that the processed thread surface is not straight and the tool tip angle changes, resulting in poor tooth shape accuracy. However, because it works with a single edge, the tool load is small, chip removal is easy, and the cutting depth is decreasing. Therefore, this machining method is generally suitable for large pitch thread machining. Because this machining method is easy to remove chips and the working condition of blade machining is good, this machining method is more convenient when the requirement of thread accuracy is not high. When machining high-precision threads, it can be completed by two knives, i.e. rough turning with G76 machining method, and then finish turning with G32 machining method. However, it should be noted that the starting point of the tool should be accurate, otherwise it is easy to buckle randomly, resulting in the scrapping of parts.

4. After the thread processing is completed, the thread quality can be judged by observing the thread profile, and measures can be taken in time. When the thread top is not sharp, increasing the cutting amount of the knife will increase the large diameter of the thread, which depends on the plasticity of the material. When the top has been sharpened, increasing the cutting amount of the knife will reduce the large diameter in proportion. According to this feature, the cutting amount of the thread should be treated correctly to prevent scrapping.

2、 Detection of common thread

For general standard threads, thread ring gauge or plug gauge is used to measure. When measuring the external thread, if the thread "over end" ring gauge is just screwed in, but the "stop end" ring gauge is not screwed in, it means that the processed thread meets the requirements, otherwise it is unqualified. When measuring internal thread, use thread plug gauge to measure in the same way. In addition to the measurement of thread ring gauge or plug gauge, other measuring tools can also be used for measurement. The pitch diameter of thread is measured with thread micrometer, the pitch diameter of trapezoidal thread and the pitch diameter of worm are measured with tooth thickness vernier caliper, and the pitch diameter of thread is measured with measuring needle according to the three needle measurement method.