Jan 30, 2020 Viewed: 137 Tag: cncmachining  

Introduction of several thread processing methods commonly used in CNC machining centers

Thread processing is one of the important applications of CNC machining centers. The quality and efficiency of thread processing directly affect the quality of parts and the production efficiency of the machining center.


With the improvement of the performance of CNC machining centers and the performance of tools, the method of thread processing is also continuously improved, and the accuracy and efficiency of thread processing are also gradually improved. In order to enable the technical staff to reasonably choose the thread processing method in the processing process, improve production efficiency and avoid quality accidents, several thread processing methods commonly used in the CNC machining center are summarized as follows:


1. Tap processing method


1. Classification and characteristics of tap processing


Tapping is the most common method for processing threaded holes. It is mainly applicable to threaded holes with smaller diameters (D <30) and lower hole position accuracy.


In the 1980's, all tapped holes were flexibly developed, that is, taps were flexibly tapped, and clamping and tapping chucks could be axially compensated to compensate for errors caused by uneven spindle speeds. Axial advance to ensure correct pitch.


The flexible tapping chuck has a complicated structure, high cost, easy damage and low processing efficiency. In recent years, the performance of CNC machining centers has gradually improved, and the rigid tapping function has become the basic configuration of CNC machining centers.


Therefore, rigid tapping has become the main method of thread processing.

The rigid tap is used to clamp the tap, so that the spindle speed is controlled by the machine tool to maintain consistency.


Compared to flexible tapping chucks, spring chucks are simple in structure, low in price, and widely used. In addition to clamping taps, it can also clamp tools such as end mills and drills, which can reduce tool costs. At the same time, rigid tapping can be used to perform high-speed cutting, improve the efficiency of the machining center, and reduce manufacturing costs.


2. Determine the bottom hole of the thread before tapping


The processing of the thread bottom hole has a great influence on the service life of the tap and the quality of the thread processing. In general, the diameter of the tapped hole drill bit is close to the upper tolerance limit of the diameter of the tapped hole.


For example, M8 threaded hole bottom Ф6.7 + 0.27mm diameter, choose some Ф6.9mm diameter. This can reduce the machining allowance of the tap, reduce the load on the tap, and increase the service life of the tap.


3. Click to select


When selecting a tap, first select the corresponding tap according to the different processing materials. The tool company produces different types of taps according to the different processing materials. Pay special attention when selecting.


Because taps are very sensitive to the material being processed compared to milling and boring tools. For example, the use of cast iron taps to process aluminum parts is prone to thread threads, random buckles, or even broken taps, resulting in scrapped workpieces. Secondly, we should pay attention to the difference between a through hole tap and a blind hole tap. The front-end guide rail of the through-hole tap is long, and the chip removal is the front-end chip removal.


The blind guide has a short front guide and the chip removal is the rear guide. It is impossible to guarantee the depth of thread processing by using a through-hole tap to process blind holes. In addition, if you use a flexible tapping chuck, you should also pay attention to the square of the diameter and width of the tapping handle, which should be the same as the tapping chuck; the diameter of the rigid tapping shank should be the same as that of the spring sleeve. In short, only a reasonable choice of taps can ensure the smooth processing.


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