Trapezoid Thread Turning on CNC Lathe
Trapezoidal thread plug gauge
We know that when turning trapezoidal threaded workpieces on CNC lathes, the surface roughness of the threads cannot be well ensured during high-speed turning, failing to meet the machining requirements, and the production efficiency is low at the time of low-speed turning, and it can be directly changed from high speed to low-speed turning. It will lead to thread chaos. I have experimented that the problem of turbulence in variable-speed turning can be solved by a simple and practical method. When turning threads, it can be turned at a higher speed and then at a low speed to finish the car and fix the light, thereby improving the production efficiency. The thread's dimensional accuracy and surface roughness are well guaranteed. 1. Variable gear turning method of trapezoidal threadThe following takes the processing of trapezoidal thread Tr36×6 as an example to introduce how to turn the trapezoidal thread on the CNC lathe of the CST980T system. Trapezoid thread workpiece shown in Figure 1.
(1) Change the workpiece coordinate system so that the turning tool does not touch the surface of the workpiece. After the roughing, the roughing tool is stopped at position X200 Z50. At this time, G50 X192 is input after the input mode, which changes the coordinate system. This is equivalent to moving the origin of the coordinate system in the positive direction of the X axis by 4mm, which is a distance slightly larger than a tooth height. At this time, the spindle speed of the lathe is lowered. If the speed is adjusted to 25r/min and the program is re-run, the roughing tool will move the vehicle to the surface of the workpiece near the workpiece surface. as shown in picture 2.
(2) Make the turning tool and the trapezoid thread groove of the car re-alignment. Because the turning tool feed speed is very slow, we can see that the turning tool is not coincident with the original thread trapezoidal thread groove, and the turning tool is biased. After a short distance, as shown in Figure 2, the goal is to reorient the turning tool to the trapezoidal thread groove in the car. The principle of operation is the same as turning a multi-start thread on a CNC lathe. This is achieved by changing the axial starting position before turning the turning tool, that is, modifying the Z-20 in the above-mentioned block G00 X40 Z-20. We can judge the generous distance to be adjusted by naked eyes. For example, we can change Z-20 to -21. After running the program, we find that the trapezoid thread groove of the turning tool and the car has not been completely aligned. Then modify the Z value and run the program again until the turning tool is completely aligned with the trapezoid thread groove. As shown in Figure 3.
(3) Restore the original workpiece coordinate system, start the finishing process To facilitate understanding and less error-prone, the tool is still moved to the X200 Z50 position. In the input mode, G50 X208 is executed, the original workpiece coordinate system is repaired, and the program is run again. It is possible to finish the trapezoidal thread at a low speed. In the finishing vehicle, the above method of changing the axial starting position before the turning of the thread turning tool is used to trim both sides of the trapezoidal thread, and at the same time, the number of times of the cutting is controlled through the measurement to make the thread meet the dimensional accuracy requirements.
After experiments, when the rotation speeds of high-speed and low-speed turning are fixed, the displacement of the turning tool needs to be fixed. With this data, it is not necessary to repeat the following when the turning tool is chipped or the tool change is required after wear. The adjustment step directly offsets the starting point of the thread at the corresponding position in the low-speed finisher. The processing example given in this article was completed on the CNC machine tool factory called CJK61352ACNC CNC lathe. When the spindle speed of lathe is changed from 560r/min to 25r/min, the trapezoidal screw turning tool needs to shift to the left by 1.8mm on the Z axis.Of course, if we still need to change the axial starting position before thread turning to reshape both sides of the trapezoidal thread at a time during mass production and processing, the production efficiency will be greatly reduced. To solve this problem, we can turn the trapezoidal thread left and right. The side of the processing process were compiled into two subroutines, each call to make the lathe axis offset 0.1mm, in the first piece of the workpiece to determine the number of subroutines to be called in the test, which will be the entire process into the program, That is, the lathe can be automatically run from the processing of the second workpiece until the workpiece is processed.
Trapezoidal thread gauge
2. The realization of variable-speed turning trapezoidal thread on simple CNC lathe Some functions such as the GSK980T, FANUC-OTE, etc. have a relatively simple CNC programming system because of the presence of compound instructions, but they do not have such functions in some domestic economic CNC lathes. At this time, we can compile the roughing process of the just-slanting method into subroutines. Each time we call a turning tool, we feed a small distance on the X-axis and Z-axis, and determine that the subroutine is called by the main program in the first test. The number of times. After completion of the roughing, the method described in the text is used to debug the displacement of the thread turning tool after changing from a high-speed roughing vehicle to a low-speed finishing vehicle to move axially, and then the machining processes of the left and right sides of the finishing thread are subprogrammed respectively. The main program can be called. 3. Points to note (1) Add cutting fluid when cutting, depending on the situation to see if you want to add the top. (2) After turning the tool from high speed to low speed, it must be strictly aligned with the trapezoidal thread groove, and be careful when operating. The method of gradually recovering the coordinate system can be adopted, that is, several times of the correction of the turning tool, so that the turning tool is gradually turned to the bottom of the alveolus. (3) The width of the cutter head of the trapezoidal thread coarse turning tool cannot be too different, otherwise the cutting allowance will be too large after the tool change, and the column collapse will occur. (4) For some large-pitch threads, the spindle speed during turning cannot be too high. Refer to the highest feedrate of the machine. Otherwise, problems such as out-of-step will occur. 4 Conclusion The actual processing proves that the above method of gear-cutting the trapezoidal thread on a CNC lathe is feasible and has achieved a very good processing effect. For other large-pitch triangular threads, worms, etc., only methods such as oblique approach, stratified approach, etc., that are used to feed the roughing tool are programmed into subroutines to debug the change from high-speed roughing to low-speed finishing. After the displacement of axial movement, the left and right sides of the fine thread are also programmed into subroutines, which can be called in the main program to complete the machining.ABS Rod sold by AHD,it's quality has been rigorously screened, with light weight, good chemical resistance, long service life, good heat preservation, smooth inner wall, no scale, no bacteria, low friction coefficient and small water flow resistance (flow rate can be increased by 30%) High impact strength, simple connection, etc.
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Product |
Diameter(mm) |
Length(mm) |
Color |
Density(g/cm³) |
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ABS ROD |
20-200 |
2000 |
Nature |
1.06 |
ABS Rod
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