Cutting tool for ordinary thread of Dalian high speed NC vertical lathe

Four standard threads, metric, inch, modulus and diameter control, can be turned on the NC vertical lathe. No matter which thread is turned, the strict motion relationship between the lathe spindle and the tool must be maintained: that is, the tool should move a lead distance evenly every time the spindle rotates (i.e. the workpiece rotates). In the following, through the analysis of ordinary thread, we can strengthen the understanding of ordinary thread, so as to better process ordinary thread.

1、 Installation and setting of common thread cutting tools

If the turning tool is installed too high or too low, when the cutting tool reaches a certain depth, the rear tool surface of the turning tool will support the workpiece, increase the friction, and even bend the workpiece, resulting in tool gnawing; If it is too low, the chip is not easy to be discharged. The direction of the radial force of the turning tool is the center of the workpiece. In addition, the clearance between the transverse lead screw and the nut is too large, resulting in the continuous automatic deepening of the cutting depth, so as to lift the workpiece and gnaw the knife. At this time, the height of the turning tool shall be adjusted in time to make the tool tip equal to the axis of the workpiece (the tool can be adjusted by using the center of the tailstock). During rough turning and semi fine turning, the position of the tool tip is about 1% d higher than the out center of the workpiece (d represents the diameter of the workpiece to be machined).

The workpiece is not clamped firmly, and the rigidity of the workpiece itself cannot bear the cutting force during turning, resulting in excessive deflection, which changes the center height between the turning tool and the workpiece (the workpiece is raised), resulting in a sudden increase in cutting depth and tool gnawing. At this time, the workpiece should be clamped firmly, and the tailstock center can be used to increase the rigidity of the workpiece.

The tool setting methods of ordinary thread include trial cutting method and automatic tool setting by tool setting instrument. You can directly use the tool to test cut and set the tool, or use G50 to set the workpiece zero point, and use the workpiece shift to set the workpiece zero point for tool setting. The tool setting requirements for thread processing are not very high, especially the tool setting in Z direction is not strictly limited, which can be determined according to the programming processing requirements.

2、 Dimensional analysis of common thread

The processing of ordinary thread by NC lathe requires a series of dimensions. The calculation and analysis of the dimensions required for ordinary thread processing mainly includes the following two aspects:

3、 Diameter of workpiece before thread machining

Considering the expansion of thread processing profile, the diameter of workpiece before thread processing is D / d-0.1p, that is, the large diameter of thread is reduced by 0.1 pitch. Generally, it is 0.1 to 0.5 smaller than the large diameter of thread according to the small deformation capacity of material.

4、 Thread machining feed

The thread feed position refers to the thread feed position Z.

Small diameter of thread: major diameter - 2 times of tooth height; Tooth height = 0.54p (P is pitch)

The feed rate of thread machining should be continuously reduced, and the specific feed rate should be selected according to the tool and working material.