In recent years, the numerical control competition has attracted the attention of all parties, and the content of the competition has gradually enriched. Machining trapezoidal thread is the most basic practice topic in general lathe production practice, and now it has become an important content in NC competition. However, in the practice of CNC lathe, due to the processing technology, there is little practice in processing trapezoidal threads, and the quality of trapezoidal threads processed is poor due to the influence of school equipment. How to process qualified trapezoidal thread with high efficiency and high quality on CNC lathe has become an urgent problem for many instructors. In fact, as long as the process analysis is reasonable and the processing instructions used are appropriate, qualified trapezoidal threads can be processed on the CNC lathe.
The processing method of trapezoidal thread shown in figure 1 is introduced below.
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20 10-7-23 17:26
Figure 1 trapezoidal thread
Analysis on Turning Process of Trapezoidal Thread
There are many processing methods of trapezoidal thread: straight advance method, oblique advance method, left-right cutting method, straight groove turning method, layered method and so on. The variables used and their meanings are shown in table 1.
Table 1 variable and its meaning
Serial number parameter content description
1 # 10 1 The machining diameter of the thread is changed from large radial diameter to small diameter during machining.
2 # 102 The tool borrowing amount on the right side increases with the increase of cutting depth.
3 # 103 The lending amount on the left side decreases with the increase of cutting depth.
4 # 104 cutting depth of each layer can be adjusted according to the situation.
3.2 procedure
Taking Fanuc 0i mateTC system as an example, the processing procedure of trapezoidal thread shown in Figure 1 is as follows:
o 000 1；
t 0 10 1 M03 S300； Change the trapezoidal thread cutter, and the spindle speed is 300 rpm.
G00 X38 Z5 walked quickly to the starting point.
M08 open cooling
# 10 1=36; Nominal diameter of thread
# 102=0; Initial value of right tool borrowing
# 103=- 1.876; Borrow the initial value of the left cutter (tg 15*3.5*2 or 0.938*2)
# 104=0.2; Depth of each bite, initial value
n 1 IF[# 10 1 LT 29]goto 2； Processing to the end of the small diameter size cycle.
G0 Z[5+# 102]； Move quickly to the right to process the cutting point.
g92 X[# 10 1]Z-30 F6； Machining tool on the right side
G0 Z[5+# 103]； Quickly process the cutting point to the left.
g92 X[# 10 1]Z-30 F6； Machining a knife on the left side
# 10 1=# 10 1-# 104; Changing thread machining diameter
# 102=# 102-0. 134*# 104; After changing the cutting depth, calculate the tool borrowing amount on the right (tg 15/2=0. 134).
# 103=# 103+0. 134*# 104; Calculate the left tool borrowing amount after changing the cutting depth (tg 15/2=0. 134).
If [# 10 1 LT 34], then #104 = 0.15; When it is less than 34, the depth of each mouth is 0. 15.
If [# 10 1 LT 32], then #104 = 0.1; When it is less than 32, the depth of each cutter is 0. 10.
If [# 10 1 LT 30], then #104 = 0.05; When it is less than 30, the depth of each cutter is 0.05.
Go to1;
N2 G92 X29 Z-30 F6； Finishing two knives at the bottom diameter.
g92 X29 Z-30 F6；
g00 x 100 z 100 M09； The tool rest quickly retreats, and the cooling is closed.
M05 Spindle Stop
M30 program ends
4 conclusion
In practical teaching and competition, trapezoidal thread is processed in layers by macro program. This simple and easy-to-understand method of turning trapezoidal threads has been fully affirmed and praised. Teachers can explain and teach the turning method to students more vividly and intuitively, and students can generally understand and master this turning method quickly and easily, which greatly reduces the difficulty and intensity of teaching trapezoidal thread turning and has achieved good results in the numerical control skill competition. Only by mastering all kinds of turning methods and skillfully using numerical control instructions can we use them flexibly in the turning process and complete trapezoidal thread turning with high efficiency, high precision and high quality.