Abstract: This paper introduces the calculation of the program and the problems in programming when machining multi-stage throttle stem of the control valve by CNC lathe. In recent years, the rapid development of numerical control technology, numerical control machine tool application and popularity of the more and more extensive, in the machinery manufacturing industry has been a large number of applications. It can be multi-coordinate linkage and easy to achieve many common machine is difficult to complete or can not be processed curves and surfaces. The multistage throttling control valve produced by our company has a great market share because of its stable work and good regulating performance. However, its multistage throttling stem is complicated in shape and difficult to process. If using a lathe with a significant number of single-board machine for processing. The program uses binary digital code preparation, the process cumbersome, heavy workload, error-prone. It is not possible to digitally modify and set the machining parameters directly. However, the use of CNC lathe programming can quickly and reasonably prepared parts processing program to achieve high-precision parts requirements. This article CK0620 CNC machine tools (operating system dual 8031 ​​as the main control unit of the two-axis CNC system) as an example of multi-stage throttle valve programming steps. 2 program calculated stem (Figure 1) throttle shape line data in Table 1. Table 1 Regulating valve stem Multi-level throttle line data H 1 2 3 4 5 6 7 8 9 10 X 15.957 15.943 15.928 15.912 15.895 15.876 15.855 15.832 15.807 15.779 Z 0.999 1.998 2.998 3.999 4.997 5.997 6.996 7.996 8.995 9.994 H 11 12 13 14 15 16 17 18 19 20 X 15.748 15.714 15.677 15.636 15.591 15.542 15.489 15.431 15.368 15.3 Z 10.993 11.991 12.99 13.988 14.985 15.983 16.979 17.975 18.971 19.965 H 21 22 23 24 25 26 27 28 29 30 X 15.226 15.146 15.06 14.967 14.867 14.759 14.643 14.518 14.383 14.237 Z 20.958 21.95 22.941 23.929 24.916 25.599 26.879 27.855 28.827 29.792 H 31 32 33 34 35 36 37 38 39 40 X 14.078 13.904 13.712 13.499 13.261 12.994 12.692 12.35 11.962 11.521 Z 30.75 31.699 32.637 33.561 34.469 35.356 36.217 37.046 37.836 38.577 Note: H-travel . In order to program the convenience and simplicity, using incremental coordinates to measure the value. The positive direction of the tool movement is the distance between the tool and the workpiece. The U value is the incremental value along the X axis and the W value is the increasing direction along the Z axis. After (Table 1) finishing calculated CNC lathe machining travel coordinates (Table 2). Table 2 Machining coordinates (U) X 0.7 0.65 0.62 0.6 0.5 0.48 0.43 0.38 0.35 0.32 0.29 (W) Z 1 1 1 1 1 1 1 1 1 1 1 (U) X 0.27 0.25 0.23 0.22 0.2 0.19 0.18 0.16 0.15 0.14 0.13 ( W) Z 1 1 1 1 1 1 1 1 1 1 1 (U) X 0.12 0.11 0.11 0.1 0.13 0.13 0.11 0.09 0.07 0.06 0.03 (W) Z 1 1 1 2 2 2 2 2 2 2 Note: U shape line The coordinate is calculated by taking the absolute value multiplied by 2 after subtracting any two values ​​of X from the last item. Then through the round and the late adjustment U diameter value. Similarly, the value of W is also subtracted from the last value of Z after taking two absolute values. After rounding and post-adjustment to get W value. But (Table 2) the value of each pair of relative coordinate changes should not be too large. To ensure that the shape of the surface after processing smooth. 3 program to write multi-level stem throttle line are the same, but the first level of the arc transition and the back two or three slightly different, to be written separately, and two or three levels of repeatedly processing the shape line G22 LXXXX ... G80 Note: (1) The program loop instruction starts from the following program of G22 instruction, ends a cycle till G80, and then returns below G22 A program execution. (2) The number of cycles is represented by L, and the four digits after L (0 ~ 9999) indicate the number of cycles. If L0000 then the program skips the loop content and executes downwardly; L0002 indicates that the loop content is executed twice, and so on. Program in Incremental Size, the program starts at the first level of throttling arc R20, starting point from the R20 arc starting X, Z coordinates 5mm apart. The programming procedure is as follows: N010 G00 U-10 N020 G01 W-4.73 F30 W direction infeed N030 G02 U-0.66 W-19.19 I34.76K-9.89 F30 N040 G01 U0 .62 W-1 F30 N050 G01 U0.61 W-1 F30 N060 G01 U0.60 W-1 F30 N070 G01 U0.60 W-1 F30 N080 GO1 UO.S0 W-1 F30 N090 G01 U0.48 W-1 F30 N100 G01 U0.43 W-1 F30 N110 G0l U0.38 W-1 F30 N120 G01 U0.35 W-1 F30 N130 G01 U0.32 W-1 F30 N140 G01 U0.29 W-1 F30 N150 G01 U0.27 W-1 F30 N160 G01 U0.25 W-1 F30 N170 G01 U0.23 W-1 F30 N180 G01 U0.22 W-1 F30 N190 G01 U0.20 W-1 F30 N200 G01 U0.19 W-1 F30 N210 G01 U0.18 W-1 F30 N220 G01 U0.16 W-1 F30 N230 G01 U0.15 W-1 F30 N240 G01 UO.14 W-1 F30 N250 GO1 U0.13 W -1 F30 N260 G01 U0.12 W-1 F30 N270 G01 U0.11 W-1 F30 N280 G01 U0.11 W-1 F30 N290 G01 U0.10 W-1 F30 N300 G01 U0.13 W-2 F30 N310 GO1 U0.13 W-2 F30 N320 G01 U0.11 W-2 F30 N330 G01 U0.09 W-2 F30 N340 G01 U0.07 W-2 F30 N350 GO1 U0.06 W-2 F30 N360 C01 U0.03 W-2.08 F30 (throttle line end) N370 G22 L0002 (cycle start second) N380 G02 U-10.6 W-5.53 I4.84 K-7.63 F30 R8 arc) N390 G02 U1.3 W-12.46 I38.6 K-5.24 F30 (car R20 arc) N400 G02 U0.78 W-0.78 I9.32 K1.81 F30 N410 G01 U0. 72 W-1 F30 (Start of throttle line) N420 G01 U0.65 W-1 F30 N430 G01 U0.62 W-1 F30 N440 O01 U0.60 W-1 F30 N450 G01 U0.50 W-1 F30 N460 G01 U0.48 W-1 F30 N470 G01 U0.43 W-1 F30 N480 G01 U0.38 W-1 F30 N490 G01 U0.35 W-1 F30 N500 G01 U0.32 W-1 F30 N510 G01 U0.29 W- 1 F30 N520 G01 U0.27 W-1 F30 N530 G01 U0.25 W-1 F30 N540 O01 U0.23 W-1 F30 N550 G01 U0.22 W-1 F30 N560 G01 U0.20 W-1 F30 N570 O01 U0 .19 W-1 F30 N580 G01 U0.18 W-1 F30 N590 G01 U0.16 W-1 F30 N600 G01 U0.15 W-1 F30 N610 G01 U0.14 W-1 F30 N620 G01 U0.13 W-1 F30 N630 G01 U0.12 W-1 F30 N640 G01 U0.11 W-1 F30 N650 G01 U0.11 W-1 F30 N660 G01 U0.10 W-1 F30 N670 G01 U0.13 W-2 F30 N680 G01 U0.13 W-2 F30 N690 G01 U0.11 W-2 F30 N700 G01 U0.09 W-2 F30 N710 O01 U0.07 W-2 F30 N720 G01 U0.06 W-2 F30 N730 G01 U0.03 W-2.23 F30 (End of throttle line) N740 G80 (End of cycle) In the program, the second and third throttle lines are programmed by cyclic instruction. Shorten the program length, make it clear and readable, improve the programming speed, reduce the possibility of error, greatly simplifying the programming process. In the program line shape at the beginning and end of the value of some changes, it is mainly based on the measured results in the process of fine-tuning, to achieve the scope of the parts tolerance, which is a normal adjustment. Program car arc command G02 arc counterclockwise milling arc, G03 arc milling clockwise, here the direction setting and commonly used FANUC, SIEMENS system in the direction of the arc command in the opposite direction. The program can be used repeatedly, through several repeated use of the program turning parts on the margin to gradually meet the drawings requirements, the completion of the rough car and finishing car parts processing. 4 Conclusion CNC lathe machining valve multi-stage throttle stem can improve the positioning accuracy and repeat positioning accuracy, making the same batch of stem interchangeability, processing quality and stability, but also greatly reduce the human factor. When the machining trajectory is a curve, the CNC machine can keep the feed constant, so the machining accuracy and surface roughness can not be affected by the complexity of the part shape, thus improving the working efficiency, reducing the processing cost and ensuring the valve is in use Process flow characteristics to meet the design requirements. References [1] Liu Xiongwei. Numerical control machine tool operation and programming training course [M] Beijing: Mechanical Industry Press. 2003. [2] Dai Shu. Metal Cutting Machine [M] Beijing: Mechanical Industry Press, 2001. [3] Fang Yi. CNC machine tool programming and operation [M]. Beijing: National Defense Industry Press, 1999. H 1 2 3 4 5 6 7 8 9 10 X 15.957 15.943 15.928 15.912 15.895 15.876 15.855 15.832 15.807 15.779 Z 0.999 1.998 2.998 3.999 4.997 5.997 6.996 7.996 8.995 9.994 H 11 12 13 14 15 16 17 18 19 20 X 15.748 15.714 15.677 15.636 15.591 15.542 15.489 15.431 15.368 15.3 Z 10.993 11.991 12.99 13.988 14.985 15.983 16.979 17.975 18.971 19.965 H 21 22 23 24 25 26 27 28 29 30 X 15.226 15.146 15.06 14.967 14.867 14.759 14.643 14.518 14.383 14.237 Z 20.958 21.95 22.941 23.929 24.916 25.599 26.879 27.855 28.827 29.792 H 31 32 33 34 35 36 37 38 39 40 X 14.078 13.904 13.712 13.499 13.261 12.994 12.692 12.35 11.962 11.521 Z 30.75 31.699 32.637 33.561 34.469 35.356 36.217 37.046 37.836 38.577 (U) X 0.7 0.65 0.62 0.6 0.5 0.48 0.43 0.38 0.35 0.32 0.29 (W) Z 1 1 1 1 1 1 1 1 1 1 1 (U) X 0.27 0.25 0.23 0.22 0.2 0.19 0.18 0.16 0.15 0.14 0.13 W) Z 1 1 1 1 1 1 1 1 1 1 1 (U) X 0.12 0.11 0.11 0.1 0.13 0.13 0.11 0.09 0.07 0.06 0.03 (W) Z 1 1 1 1 2 2 2 2 2 2 2