[0012] The present invention will be further described below through specific embodiments.
[0013] The sawtooth thread turning method includes the following steps:
[0014] a. Preparation before turning: select the tool that meets the requirements according to the geometric parameters of the thread, determine the roughing amount and finishing allowance, and complete the tool setting work;
[0015] b. Rough turning: Turning by shifting straight forward method. First, take the working surface of the thread groove as the reference, move the tool forward, after cutting to a certain depth, retract the tool, and then move the tool pallet to the non-working surface of the thread groove by one less than The tool nose width is 0.5~1mm, and the tool is fed again. When the cutting edge of the working surface of the tool is close to the last feeding position or the tool is close to the bottom position of the thread, the feeding is stopped, and the tool is retracted after turning. Repeat the above steps until The width of the thread groove is only the amount of light knife left;
[0016] c. Finish turning: also adopts the shifting straight forward turning method. Firstly, the working surface of the thread groove is turned, and at least two radial feeds are used when the tool is fed. The cutting edge and the thread of the working face of the tool are guaranteed during the last feed. The working surface of the groove is in full contact, and then the tooth bottom and the non-working surface of the thread groove are turned in the same way.
[0017] The geometric parameters of the cutting part of the turning tool have a great influence on the surface quality and cutting performance of the part. The geometric shape and related parameters of the tool should be correctly selected according to the shape of the part, the installation position of the tool, and the processing method. Cutting tools for sawtooth thread, considering the convenience of grinding and toughness and other factors, in most cases are grinding with high-speed steel tools, before the formal processing, the rough machining amount and finishing allowance need to be calculated and determined.
[0018] When roughing, first feed the tool based on the thread groove working surface. At the beginning, the straight approach is generally used, because the front body of the tool tip is too small, and the high-speed steel has poor heat resistance and poor heat dissipation. , The strength is poor, so the depth of the knife is not easy to be too large. After the first thread groove is cut, retract the tool to the starting position, move the tool holder to the non-working surface of the thread groove a distance less than the width of the tool nose by 0.5-1mm, and feed again, this time the tool will work The face cutting edge is about to touch the working surface of the previously turned thread groove or when the tool approaches the bottom of the thread, and then turn it. After the thread groove is cut, repeat the above steps again until the width of the thread groove is only left Up to the amount of light knife, the amount of light knife refers to the fine turning allowance of 0.10~0.30mm on each side.
[0019] The advantage of this shifting straight forward method is that the chips are discharged obliquely outwards, and it is not easy to scratch the working surface of the thread groove. At the same time, the chip evacuation is smooth, and the chips will not cause burning, beating, gnawing, sticking and scratching on both sides due to stacking. The two sides of the thread groove processed in this way can obtain a good roughness value, generally between Ra3.2 and Ra6.3, which lays a good foundation for obtaining a good surface roughness for fine turning. The working surface of the thread groove may be There will be some unevenness, and these defects can be left to be processed in finishing.
[0020] When finishing, the shifting straight forward method is also used, and the finishing tool must be sharp and the cutting edge flat. If the thread groove is deep and the entire side surface is prone to chattering, the turning should be divided into at least two times. When the depth is reached, the entire side surface is just flat and the roughness meets the requirements, it is not easy to repeatedly turn, otherwise it may cause Tremor, thereby destroying the flatness. Then use the same method to turn the bottom and non-working surface of the thread groove.
[0021] When the tool is turned to a certain depth, the chip removal problem will occur when the depth of the tool is 3 mm on one side. Because the tool eats the tool on three sides, the chips are crowded together and go out. At this time, the chip removal is not smooth, although there is sufficient The cooling fluid is poured, but the cutting temperature at the front of the tool tip will rise rapidly, which will cause errors. Therefore, the depth of the first feed should not be greater than 3mm.
[0022] According to the choice of the tool, the feed is carried out according to the shift and straight approach. It is possible that the tool has moved laterally to the thread groove and only the amount of light left is left. The tool has not been processed to the bottom of the thread. The tooth bottom on the side is bottom turned. In order to improve efficiency, the axial feed can be directly used for machining when turning the bottom of the tooth.
[0023] In the whole turning process, cutting fluid is indispensable because high-speed steel tools are used for turning. When rough turning, because a large amount of excess metal needs to be removed, a large amount of cutting heat will be generated. In order to reduce cutting temperature and reduce tool wear, an emulsion with a concentration of about 5% is generally used. A lower concentration of aqueous solution has better permeability And cooling performance, can achieve cooling effect. When finishing turning, the surface roughness value is required to be small. Generally, a higher concentration emulsion of 10% to 15% is used to make the surface smooth and shiny with mirror effect. A 1:3 mixture of kerosene and engine oil can also be used. The good permeability, cleaning and lubricity of kerosene can be used to maintain the sharpness of the cutting edge and smooth chip removal. The surface after turning is not as good as high-concentration emulsions. Good, but the actual roughness value is comparable and can improve tool durability.
[0024] The key point of the present invention is that it adopts the feed method of the shifting straight forward method. Although some operation steps are added in actual application, it solves the problem of chip removal and ensures the accuracy and roughness of the thread. , It will not cause burning, beating, gnawing, piercing and scratching the sides of the thread groove, etc., and has good practicability and application prospects.
