The flat thread is also called the end thread. And its tooth shape is the same as the rectangular thread, but the flat thread is usually the thread processed on the end face of the cylinder or the disc. The trajectory of the turning tool relative to the workpiece when machining a flat thread is an Archimedes spiral, which is different from the normally machined cylindrical thread. This requires one revolution of the workpiece, and the middle carriage moves the pitch on the workpiece laterally. Below we will specifically introduce how to turn plane threads in machining.
Features of threads:
In mechanical machining, we use thread connections widely, both external and internal. There are four main types according to the shape of the thread profile: triangular thread, trapezoidal thread, serrated thread and rectangular thread. According to the number of threads of the thread: single thread and multi-thread thread. In various machines, the role of threaded parts is mainly the following: First, for fastening and connection. The second is to transmit power and change the form of exercise. Using triangular threads to connect other parts. And use trapezoidal threads and rectangular threads to transmit power and change the form of motion. Their technical requirements and processing methods vary depending on their application.
How to machining?
In order to effectively reduce the processing difficulty of machining threads, improve work efficiency, and ensure the quality of thread processing, we usually use CNC machine tools.
We use three commands G32, G92 and G76 in CNC machining.
G32: It can process single-stroke thread, single programming task is heavy, and the program is more complicated;
G92: Can realize a simple thread cutting cycle. And it’s helpful for simplifying program editing, but requires the workpiece blank to be roughed beforehand.
G76: Overcome the shortcomings of the command G92, can complete the workpiece in one time. Saving programming time is a great help for simplifying the program.
G32 and G92 are straight-cut cutting methods, and the two cutting edges are easy to wear. This is mainly due to the simultaneous work of the two side edges, the large cutting force and the difficulty in cutting. When cutting a thread with a large pitch, the cutting edge wears faster due to the large depth of cut, which causes an error in the diameter of the thread. However, the precision of the processed tooth shape is high, so it is generally used for small pitch thread processing. Due to the fact that its tool movement cutting is done by programming, the machining program is longer. But it is more flexible.
G76 is a diagonal cutting method. Because it is a single-sided edge machining, the right edge is easily damaged and worn, making the machined thread surface not straight. In addition, once the tool nose angle changes, the accuracy of the tooth shape is poor. However, the advantage of this machining method is that the cutting depth is decreasing, the tool load is small, and the chip removal is easy. Therefore, the processing method is suitable for the processing of large pitch threads.
