The extrusion tap control software of NC tap grinder is introduced in this paper. The technological characteristics of relief grinding of extruded tap with polygonal cross section are studied. The electronic cam function of TRIO motion controller and virtual axis technology are used to solve the problem of overlapping the trajectory of relief grinding between the front taper thread and the polygon section of the extrusion tap, and the pitch error of the top of the teeth in the transition zone between the front taper thread and the straightening thread. The NC display, control and management of extrusion tap processing are realized by touch screen man-machine dialogue. With the wide application of non-ferrous metals, alloys and other materials with good plasticity, especially in the IT industry, chips are discharged when cutting taps are used. Cold extrusion chip-free processing is a new method of internal thread processing, that is, cold extrusion is used to make the bottom hole of the workpiece plastic deformation and form internal thread, and the surface of the thread is smooth, strong and wear-resistant. The application of this technology is becoming more and more extensive, and the grinding of extruded taps has been paid more and more attention. Most of the equipment for extrusion tap processing in domestic tool industry are traditional mechanical threading grinders. It is difficult to adjust the relief grinding of polygonal cross section, thermostatic element and the pitch error of the top of the teeth in the transition zone exists. Some enterprises choose imported fully automatic CNC extrusion tap grinder, but the price is expensive and the maintenance is inconvenient. According to the market demand, the extrusion tap control software is developed on the basis of the original NC tap grinder. The parameters of human-machine setting for truncation are as follows: angle of ridge top and round angle theta, angle of falling arc beta 1, angle of inner circle gamma 1, angle of rising arc beta 2, and relief abrasion K. B. Straightening area teeth: the top of the threaded teeth is of the same height. C. Transition zone teeth: As shown in Figure 4, the area where the bottom of the teeth rotates from point A to point B is the transition zone from the front cone zone to the straightening zone thread. D. Thread full length (L) with inverted taper and tail taper at the end of thread. Thread processing needs to move the workpiece to the right P/2 to ensure that the step break point is eaten by the bottom of the teeth. In order to ensure that the width of the front cone is the same as that of the aligning top, the height of the front cone is 2.5*H during thread processing. Error analysis of top pitch in transition zone: The pitch of traditional thread grinder is a mechanical hanging wheel structure with constant bottom pitch. But there is pitch error in the transition zone.
In the actual tapping process, the top of the transition zone bears great force and is easy to crack. Fig. 3 The top width of ridge teeth in transition zone is 0.06mm, and the pitch of adjacent top teeth in transition zone is 0.48 mm. The top width of the front cone and straightening zone is 0.
1 mm and the pitch of the top is 0.5 mm. In order to ensure that the top pitch of transition zone is correct. Fig. 4 uses the inverse derivation method to arrange the top pitch of the front cone and the aligning thread according to the P value.
The bottom of all threaded teeth is connected by drawing point method. Results The trajectory of the transition zone at the bottom of the threaded teeth is AB oblique segment, and the distance between AB is P X. Compensation value is X=P/2*Tan30*Tana, alpha is the angle of the front cone, P is the pitch. The trajectory decomposition method is adopted: the trajectory is decomposed into two simpler mathematical models, and then the two mathematical models are superimposed to form a complex trajectory. Mathematical model of virtual axle 6: The motion track of axle 6 is the front cone of extrusion tap. Workpiece 360 degrees take 100 points. Control is shown in Fig. 5 and Fig. 6 below. Mathematical model of axis 2: The trajectory of relief grinding of axis 2 is a polygon section. The electronic cam is defined as 100 points per degree, 120 points of triangular type and 12 000 points per degree.
Thread full-length cycle control is shown in Figure 7 below. The motion program is: CAMBOX (0,12000,16,12000,3) AXIS (2) superimposes the axle 6 trajectory on axle 2 and instructs ADDAX (6) AXIS (2) to realize the relief grinding motion of the front cone and polygon cross section.
Mathematical model of virtual axle 7: The trajectory of axle 7 is shown in Fig.
9 as compensation X of top pitch in transition zone. One circle of work piece takes 100 points. The compensation of pitch error on top of teeth in transition zone and the processing of full thread pitch are realized. CONCLUSION: The relief grinding motion of the front cone thread and polygon section of the extrusion tap is numerically controlled. Section only needs to set parameters according to the process, so it is easy to operate. The design of extrusion tap control software is reasonable, which improves the quality and processing efficiency of extrusion tap. But the equipment is manually loaded and unloaded, while the American fully automatic CNC extrusion tap grinder is fully automatic control, with high production efficiency and low labor force. So the intelligent control of the equipment still has a lot of room for development.