The ordinary wire cutting machine tool is a typical two-axis linkage type numerical control machine tool. Generally, it can only be used as a cutting process for various kinds of two-dimensional graphics. The range of its processing technology is relatively narrow. How to broaden the range of the processing technology of ordinary wire-cutting machine tools so that it can better meet the objective production needs has always been the concern of the majority of wire-cutting users. Based on the author's years of practical work experience, this article describes in detail the method of spiral machining on an ordinary wire-cutting machine.
A: The realization of spiral movement
Spiral motion is composed of two basic motions: linear motion and rotational motion. To achieve spiral machining on an ordinary wire-cutting machine, in addition to using a linear (X-axis or Y-axis) linear cutting machine to obtain linear motion, we must also use another axis (Y-axis or X-axis) and necessary The auxiliary device turns the workpiece. Proceed as follows:
1. According to the existing wire-cutting machine used in the step-variable transmission (including gearbox and stepper motor) models directly to the manufacturer to buy another set or create a set of their own. If it is made by oneself, the main parameters (including the parameters of the stepper motor and the speed ratio of the gearbox) are preferably the same as the original one, which can simplify the programming problem in the later specific processing. Also note:
(1) The gears in the gearbox should be engaged with each other without gaps. In order to ensure the machining accuracy, reverse gaps are absolutely not allowed. It is usually possible to eliminate the gear meshing gap by using a two-piece thin gear stack as shown in FIG. 1 and adding a tension spring in the middle.
(2) The front, rear, top, bottom, left and right faces of the gearbox are to be perpendicular to each other, and the shafts in the gearbox must be parallel to each other and perpendicular to the front and rear faces to meet the requirements. The need for calibration and accurate positioning of the workpiece during specific machining.
(3) The production of the output shaft end structure should be conducive to the rapid and accurate positioning of the workpiece.
2. The above step-by-step transmission device as shown in Figure 2 is fixed to the workbench of the WEDM. The gearbox body is calibrated with a dial gauge prior to fixing to ensure that the output shaft of the stepper gear is parallel to the X axis of the machine tool. Connect the wire (four wires) of the Y-axis stepper motor of the wire cutting machine and connect it to the new stepper motor with a wire stub. Pay attention to the correctness of the connection; otherwise, the stepper motor will not work properly.
3. Test the operation of the newly installed stepper. Enter a simple program such as: B0 B0 B4000 GYL2 in the controller, see if its rotation is steady, each gear's meshing condition is ideal, and add lubricant to the gear. Generally, there should be no gaps and no noise in the gears, and the output shaft should be stable and flexible. Consider the length of the count that should be entered if you want to rotate the workpiece one revolution. How to control the rotation direction of the workpiece?
II: Programming and Processing
Figure three
As shown in Fig. 3, a cavity part of a mold for producing a razor screw hob part is shown. The drawings require that ten spiral grooves with a length of 25 mm, a width of 0.12 mm and a relative rotation angle of 90 degrees be machined on the cylinder. Obviously, using conventional processing methods cannot be achieved.
Now, we use the above device to use the line cutting method to complete the processing.
First, the workpiece is fixed to the output shaft of the stepper gear, and the center of rotation of the workpiece is aligned with the axis of the output shaft. I chose to make the end of the output shaft match the 6.00mm boss to match the 6.00mm bore in the workpiece (as shown in Figure 2). Considering that the width of the spiral groove is 0.12 mm (the groove used for the positioning of the groove of this groove type spiral hob) and the discharge gap during wire cutting, an electrode wire with a diameter of 0.1 mm is used.
Next, center the workpiece to ensure that the wire passes through the center of the workpiece.
Then you can enter the program for processing. Taking a machine tool with a 4 mm pitch ball screw as an example, taking into consideration that the output shaft rotates one revolution, the program has a record length of 4,000 units, and the current relative rotation angle is 90 degrees, that is, it requires a rotation of 1/4 week. Therefore, when cutting each spiral groove, the length required for rotation is 1000 units. Therefore, the procedure is as follows:
1. B25000 B1000 B25000 GXL4 (Cut program)
2. B25000 B1000 B25000 GXL2 (retraction program)
3. B0 B0 B400 GYL2 (indexing procedure)
4. B25000 B1000 B25000 GXL4 (Cut program)
5. B25000 B1000 B25000 GXL2 (retraction program)
6. B0 B0 B400 GYL2 (indexing procedure)
7. B25000 B1000 B25000 GXL4 (Cut program)
8. B25000 B1000 B25000 GXL2 (retraction program)
9. B0 B0 B400 GYL2 (indexing procedure)
10. B25000 B1000 B25000 GXL4 (Cut program)
11. B25000 B1000 B25000 GXL2 (retraction program)
12. B0 B0 B400 GYL2 (indexing procedure)
13. B25000 B1000 B25000 GXL4 (Cut program)
14. B25000 B1000 B25000 GXL2 (retraction program)
(The program is completed, in fact, the workpiece can be completed by half a revolution.)
Finally, using the above program to process the workpiece, you can easily get the results required by the drawings. Of course, the processing process should also pay attention to the stability of the processing current and processing speed. It is better to turn off the high frequency in the wire retreat process to prevent repeated cutting and increase the width of the spiral groove.
Three: Conclusion
The realization of the above spiral processing method greatly broadens the range of the processing technology of the ordinary wire-cutting machine tool, so that the ordinary wire-cutting machine tool can better meet the actual production needs. I have been engaged in wire-cutting-related work for many years. During this period, the above-mentioned methods have been successfully used to solve the wire-cutting problem of spiral-type workpieces many times. In addition to this example introduced to everyone, the successful completion of the multi-color ballpoint pen wheel mold parts, lipstick parts for women's lipstick box, cylindrical cam parts, face gear parts and other processing, online cutting spiral processing accumulation A certain amount of experience. Finally, I warmly welcome my colleagues who are interested in the above content to contact me to discuss and make progress together.