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Figure 1 Part Drawing

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Figure 2 Expanded schematic

Our unit processes the parts shown in Fig. 1 (Material: 2OCrMnTi, normalizing, 170-200HB) because it has a large lead of 150mm and is a closed ring 8 shape. We adopted the tapered thread cutting method on CNC lathes to successfully complete the machining of this part. 1 Technological scheme and cutting principle The oil line consists of two closed curves with a phase difference of 180° as shown in the unfolded view of Figure 2. If the ordinary lathe soil is used to make a modified tailstock, it is difficult to complete it once. Only after one curve is drawn, the workpiece is rotated 180° and then re-clamped. The use of a hanging wheel to link the hand-dividing head with the feed mechanism of the milling machine also has a phase problem in milling the part. At the same time, in order to obtain a more ideal curve shape, the smaller the diameter of the milling cutter, the better. This will inevitably lead to a slender cutter shaft, poor rigidity, reducing cutting efficiency. The use of special technological methods for CNC lathes can compensate for the defects of ordinary turning and milling machines. First of all, when a CNC lathe turns a thread, a one-rotation signal is sent from the spindle position encoder. After the CNC system receives this signal, the thread cutter starts immediately. The thread is cut, and the relative distance between the starting points of the tool can be adjusted by adjusting the phase. , namely: S=NL/360
In the formula: S—the relative distance of the starting point of the thread cutter, mm N—the phase difference of the curve, degree L—the thread lead, mm For the part of figure 1, S=180×150/360=75mm, ie the first After the curve processing is completed, the tool is moved to a distance of 75 mm from the original starting point, and the second curve is turned, and the two are combined to form a closed 8-shaped oil line that meets the requirements of the drawings. Second, in order to ensure the aesthetic appearance of the parts, the trajectory of the retracting knife and the curve must be exactly matched. We use the taper thread cutting method to increase the depth of cut in each cycle of the contour profile forming process. After reaching the drawing requirements, we can use the taper thread command to retract the blade. The effect is ideal. 2 Programming According to the geometrical elements of the part outline given in the drawing, the following forming procedure is obtained: Main program O0001; G50 X200.0 Z150.0; Determine the starting point of the machining and the origin of coordinates (the origin of the coordinates is set at the intersection of the center of the part and the front end) G0 X59.0 Z5.0; Sloping line quickly approaching part Z -7.5; Tool reaching oil line starting point A M98 P0002 L8; Calling subroutine 8 times, car first oil line W -75.0; Finishing depth W10.0 U -4.0; Retract the tool with taper threading method to G0 Z -82.5; The tool quickly reaches the starting point of the second curve at the machining point M98 P0003 L8; Call the subroutine 8 times, turn the second curve W75.0; Trim the depth of cut W -10.0 U -4.0; Retract the tool G0 Z5.0 with taper thread; Exit the part cavity X200.0 Z150.0; Go back to the processing starting point M30 with a slash; The main program ends the subroutine O0002; G32 W-75.0 U0 .5 F150.0; Turning curve right-hand part and diametrical feed 0.5mm W75.0; Turning curve left-hand part M99; Subroutine end subroutine G32 W75.0 U0.5 F150.0; Turning curve right-hand part Diameter direction infeed 0.5mm W75.0; Turning curve right-hand part M99; Subroutine ends the above programmed program parts Profiling procedure, if used for actual machining, the rotational speed of the spindle needs incorporated, tool number and tool change command, and the command with the coolant. It should be noted that the spindle speed setting must satisfy both the cutting torque requirement and the maximum feed speed limit in a specific CNC lathe.

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