About the processing of thread processing of CNC lathes

Speaking of CNC lathes , it can turn four standard threads, including metric, foot, module, and diameter control. No matter which type of thread is turned, the lathe spindle and the CNC blade must maintain a strict motion relationship: that is, the spindle. Each rotation (i.e., the workpiece rotation), the CNC blade should move evenly the spacing of one (workpiece) guide. The following is to strengthen the mastery of various threads based on the analysis of various threads to better process various threads.

Specification analysis of ordinary threads

CNC lathes also require many specifications for processing ordinary threads. The measurement and analysis of ordinary thread processing specifications mainly includes the following two aspects:

1. Diameter of steel component before thread processing

According to the shrinkage rate of the thread processing tooth type, the workpiece aperture D/D-0.1 P before processing the thread, that is, the thread diameter is reduced by 0.1 pitch, which is usually 0.1 to 0.5 smaller than the thread diameter according to the deformation of the material;

2. Number of thread processing feeds

To increase the thread blade, you can refer to the thread diameter, that is, the last lowering part of the thread blade.

Its diameter is: large diameter - 2 times tooth height; tooth height = 0.54 P (P is the pitch)

The amount of cutting tools used when cutting threads should be continuously reduced, and the actual amount of cutting tools is selected based on the CNC insert material.

About the selection and alignment of ordinary threaded CNC blades

If the tool is installed too high or too low or too high, when the feeding tool reaches a certain thickness, the back of the milling cutter contacts the steel parts, increasing sliding friction, and even bending the workpiece, causing a knife gnawing condition; when feeding the tool, The cutting amount is difficult to discharge, and the direction of the axial force of the feeding tool is the center of the workpiece. In addition, the angle between the screw and the nut is too large, causing the feeding tool to automatically continue to thicken, which makes the feeding tool thicker. Show knife gnawing. At this time, the height-to-wide ratio of the turning tool should be adjusted immediately so that the blade is equidistant from the center line of the workpiece (the tool can be set with the tip of the tail seat). When drilling and semi-finishing, the cutting edge position is 1% higher than the workpiece outlet position D and D (D indicates the hole diameter of the workpiece being processed).

The stiffness of the unstable workpiece cannot withstand the cutting force during cutting, resulting in excessive deflection, which changes the central height between the turning tool and the workpiece (the workpiece is lifted), resulting in a sudden increase in cutting thickness, and a knife-bitching phenomenon occurs. At this time, the workpiece should be clamped firmly, and the tailstock tips can be used to improve the workpiece stiffness.

There are two types of ordinary threaded tool alignment methods: tool test method and automatic tool alignment device. You can directly test-cut with CNC blades, or you can set the workpiece zero point by G50, and use the workpiece movement to set the workpiece zero point for tool alignment. The standard for spiral processing is not high, especially the standard for z-direction tool alignment is not strict enough, and can be processed according to the standard of procedure processing.

About ordinary thread processing

Currently , in CNC lathe processing , there are generally three processing methods for thread processing: G32 direct processing, G92 direct processing, and G76 oblique processing. Due to different turning and programming, the processing errors are also different. We must carefully analyze the applications in production and strive to process high-precision parts.

G32 straight-in turning method, due to the coordinated working of the double-sided edges, the cutting speed is high and the cutting is difficult, so the two-sided edges are easily damaged during turning. When turning large pitch threads, due to the large turning depth, the blade is quickly damaged, which causes deviations in the middle diameter of the thread; but the toothed parts processed are relatively high, so small pitch threads are generally used for processing. Since its blade movement is completed by programming, the machining procedure is relatively long; considering that the blade is prone to wear, it is necessary to ensure frequent measurement during processing.

The G92 direct turning method is optimized to program, and the improvement speed is faster than the G32 console command.

G76 oblique cutting method takes into account that when cutting side edges, the machining side edges are easily damaged or damaged, the machining thread surface is not straight, and the cutting tip angle changes greatly, resulting in poor tooth shape accuracy. However, due to the single-sided cutting, the CNC insert has a small load, is easy to remove chips, and the turning thickness tends to decrease. In this way, this processing method is generally suitable for processing large-game threads. Because this processing method is easy to remove chips and has good cutting edge processing conditions, it is more convenient when the thread precision is not specified. For the processing of higher precision threads, double-cutting can be used, which can be processed with G76 first and G32 processing method to be processed with precision. But remember to remember that the starting point of the cutting tool must be accurate, otherwise it will be easy to buckle randomly and cause parts to be scrapped.

After the thread processing is successful, you can also carefully observe the thread shape to determine whether the thread has quality improvement measures. When the thread head is not pointed, the cutting amount of the lifting knife will increase the large diameter of the thread. The increase amount depends on the ductility of the material. , When the threaded head is pointed, the cutting amount of the enlarged knife will decrease. According to this feature, the cutting amount of the thread should be correctly viewed to avoid scrapping.