Machining thread in machining center is one of the most important applications. In the process of thread processing, the quality and efficiency of the machining directly affect the quality and efficiency of the part. Below we will introduce the thread processing methods commonly used in actual machining, as well as the selection of thread machining tools, NC programming and analysis and explanation of precautions. So that the operator can choose the appropriate processing method to improve the efficiency of the machining center.
A.Flexible tapping and rigid tapping comparison
In the machining center, tapping the tapped hole is a common processing method, and it is suitable for threaded holes with small diameter and low hole position accuracy. It has flexible tapping and rigid tapping two methods.
Flexible tapping, the tap is clamped by a flexible tapping chuck, and the tapping chuck can be axially compensated to compensate the feed error caused by the axial feed of the machine tool and the spindle rotation speed, and ensure the correct pitch. Flexible tapping has the characteristics of complex structure, high cost and easy damage. Rigid tapping, mainly using a rigid spring head to hold the tap, the spindle feed and the spindle speed are consistent with the machine tool, the structure is relatively simple, the price is relatively cheap, and the application is wider, which can effectively reduce the tool cost.
In recent years, the performance of the machining center has gradually improved, and the rigid tapping function has become the basic configuration of the machining center, which is the main method of thread processing.
B.Selection of taps and processing of threaded bottom holes
The taps need to be selected according to the processing materials. According to the different materials processed by the tool company, there will be corresponding tap models. Secondly, pay attention to the difference between the through-hole tap and the blind-hole tap, and the leading end of the through-hole tap is long. And the depth of thread processing cannot be guaranteed, if the blind hole is machined with a through-hole tap.
A.Thread milling features
Thread milling means use thread milling cutters to mill the thread. The advantage of milling threads relative to taps is that they can achieve chip evacuation and cooling, effectively avoiding the quality problems such as tooth loss and chaos in the process of tapping. At the same time, when the diameter of the thread is large, the tap is used for machining, and the spindle power of the machine tool cannot meet the processing requirements. With the drilling machine tapping, the processing efficiency of the thread is low, and the labor intensity of the worker is large. The thread milling process can realize the characteristics of small force and good chip removal, and has the advantages of high thread processing precision and small surface roughness value.
B.The principle of thread milling
a. Thread milling macro processing
During the processing of the cylinder head, there are a plurality of boring holes on the side. Previously, the tapping of the drill tap was used, resulting in high labor intensity, low processing efficiency, quality problems such as tooth loss, and rapid wear. In order to improve the processing quality of the thread, a new tool multi-tooth thread milling cutter is used in the machining, and the horizontal machining center is used for processing.
b. Thread milling multi-tooth milling program
According to the actual measurement, the effective length of the multi-tooth thread milling cutter is larger than the thread length of the threaded hole machining, and the running track of the tool is set. This method ensures that each effective tooth on the multi-blade thread milling cutter participates in the cutting at the same time, thus completing the entire threading process quickly.