Threaded CNC cutting process

Nanjing Yongguang Group Computer Application Center (210006) Zhou Yonglin wipe, which will lead to the formation of built-up edge, high surface roughness and the right working distance is the thread distance. The use of indexable thread turning tools for threading in the CNC lathes and machining centers for the correct and rational selection of threads is very important to the user. This article discusses this.

The cutting process of the thread depends on the structure of the part being machined and the CNC machine used. In general, the right-handed edge is used to machine the right-handed thread and the left-handed edge is used to machine the left-handed thread. This has the advantage that the support of the blade is the most stable. Of course, the opposite method can also be applied.

Consistent, so as to avoid excessive wear on the side of the blade and shorten the life of the tool as much as possible.

D2??Medium diameter A??The angle of inclination of the blade can usually be indexed. The angle of inclination of the thread turning tool is determined by the knife pad. The standard knife is + but for internal thread tools with diameters of 16mm and 020mm, there is no knife pad due to small space. Therefore, it is not machinable when the blade inclination angle is greater than +2°.

The threading method of thread turning is determined by the cutting machine tool, the workpiece material, the insert geometry and the pitch of the thread being machined. There are usually four types of feeding methods: the most common cutting method, the cutting of the left and right edges of the turning tool simultaneously The axial cutting component is offset, which partially overcomes the phenomenon that the turning tool is biased due to the axial cutting component. Uniform wear on both sides can ensure the shape of the teeth is clear, but there are problems such as poor chip removal, poor heat dissipation, and concentrated stress. It is suitable for cutting the thread D single-side infeed tool with a pitch of 1.5mm or less and cutting in the direction of the radial angle. The chips are rolled up from the blade to form strips of chips, which is better for heat dissipation. The disadvantage is that the other blade is cut in the direction of 30° angle due to the non-cutting of the workpiece. The cutting edge is cut on both sides to form roll-shaped chips, the chip removal is smooth, the heat dissipation is good, and the rough surface value of the thread surface is low. In general, this is the best way to turn stainless steel, alloy steel and carbon steel. This method is used in about 90% of threaded materials. This method is best used for threading on CNC lathes. Generally, fixed cycles can be called for easy programming.

The left and right sides alternately feed the knife alternately to the left and right alternately, that is, each time the radial feed is made, the lateral direction is shifted to the left or to the right by a certain distance, so that only one side of the turning tool participates in the cutting. This method is generally used for threading of general lathes and media distances above 3mm, and programming on CNC lathes is more complicated.

Thread milling is mainly used in CNC boring and milling machines such as machining centers. Generally, the small-diameter internal thread (矣20mm) can be tapped, but for the machining of large-diameter internal threads and the machining of external threads, there are many problems in tapping and threading, so the medium-cut iron cutting is the best processing. means.

Thread milling is different from thread turning and X. This is because 瞟 数控 CNC milling is mainly realized by the three-axis linkage and helical interpolation machining of the machine tool, that is, while the two-axis is arc-sensitive processing, The three-axis linear feed motion, the axial movement distance milling, is a single-blade milling process, so the feed mode is preferably a radial direct feed cutting method, so that the two cutting edges are simultaneously cut and the force is relatively uniform. It can guarantee thread precision and CNC programming is relatively simple.

Second, the choice of thread turning and milling cutting The choice of thread cutting amount (cutting speed, backing amount, number of passes) is determined by the material of the tool and the part. The cutting speed of thread turning is generally 25%~50% lower than that of ordinary turning. The choice of thread backing and the number of passes is also particularly important. The correctness of the D value is directly related to whether the medium is qualified or not. The amount directly affects the size of the cutting force. The amount of knives to be eaten is to follow the principle of decreasing, that is, the latter knife must be smaller than the previous knife, and the minimum back knife value is not less than. 5 stomach. The following two tables provide the value of the inner and outer media of the metric. This table is also suitable for the milling of threads.

Table 1 ISO rice grain back knife value (external thread) (mm) pitch back child cutting times taste distance back knife amount of cutting times table 2ISO meters grain back knife value (internal thread) cadmium distance back knife knife cutting The number of times of cutting the back of the knife is the number of cuttings for CNC boring and milling machines. Although the milling thread is realized by three-axis helical interpolation, it is different from the turning thread, but the cutting amount can still be selected. The relevant cutting parameters of the grain. Since the milling thread is made by single-blade cutting, the cutting speed should be half of the turning speed, and the value of the backing knife can still be selected by turning.

Third, the thread turning and milling NC program preparation For the CNC lathe, the general standard thread turning programming command is G33 (fixed pitch cutting), G34 (pitch incremental variable pitch butterfly cutting), G35 (pitch decreasing pitch) Thread cutting). The media distance is specified by /, human ruler, where K /, A: respectively correspond to the X and Z axes. However, general CNC systems and machine tool manufacturers provide threaded turning fixed cycles for users to use, just enter the necessary parameters. H has to use the G command and the programming method of calculating the coordinate point by itself when processing a special butterfly pattern.

The thread milling process is programmed differently than CNC turning. The main use of G02, G03 circular interpolation command, that is, the second axis linear interpolation at the same time as the two-axis circular interpolation, forming a helical interpolation movement, the following is the ordinary internal thread M30X 2, deep 14mm CNC milling program The amount of the back knife is 1.2mm, and the direct cutting method is adopted.

F200 takes the blade compensation, and the radial feed to the backing knife position is often due to the correctness of the selection of the tool (including the blade, the knife pad and the tool bar), the feeding mode, the cutting amount, etc. in the crepe cutting. Affect the processing quality of crepe, such as: the surface of the thread has a shock pattern, the surface roughness value 篼 This may be due to the excessive extension of the part or tool, the rigidity is poor, the tool center is too 篼, the cutting amount, the blade, the blade are not selected correctly. Caused by other factors. It can be used to increase or decrease the cutting speed, shorten the outer extension of the tool, adjust the center height or the feed mode, use the side feed or the radial feed, fully cool, and increase the number of passes.

The tool wears fast and the tool life is short. Because the cutting speed is too fast, the cooling is not enough, the cutting times are too many, and the blade number is incorrect. It can reduce the cutting speed, fully cool, reduce the number of cutting, select the blade with good hardness of the wear-resistant blade D, change the cutting angle, increase the cooling, increase the cutting speed, reduce the amount of back-feeding, and adjust the center 篼.

Two cutting edges wear unevenly into the knife mode, cut people angle workers (cold processing> Shan Dongfang Construction Machinery Factory (Haiyang City 265100) Yu Guobo years achieved sales revenue of 296 million yuan. Need a variety of bearing brackets Most of the materials use HT200. The bearing brackets are as shown.

The traditional processing process, first scribing the bottom surface, and then processing on the T611 boring machine, each piece of correction is required during processing, the clamping is troublesome, time-consuming and laborious, and inefficient.

Insufficient processing capacity, therefore, we designed a H7rr35) with a center height of 257s for the bearing bracket with the design of the special tooling fixture for the vehicle, which is the main size of the workpiece. According to this, the fixture is designed as shown. The fixture is used on the CW6263 lathe.

The jig consists of a main body 3 and a three-jaw self-centering chuck 4. Disassemble one of the claws of the three-jaw self-centering chuck, the left end of the main body 3 is connected with the chuck, and is fastened by the bolt 1. The positioning surface of the bearing bracket of the A-side table is provided with two notches for facilitating the free movement of the claws. s Firstly ensure the center of the bearing bracket 5, and then use the three claws to choose from improper, to change the way of feeding and cutting the angle.

The built-up edge on the cutting edge increases the cutting speed, increases cooling, and uses a coated carbide insert to cut with a modified side feed.

The tool produces excessive plastic deformation. This is due to poor cooling and high cutting speed. The selected blade number is wrong, and the amount of back-feeding knife is too large. Should reduce the amount of back knife, increase cooling, reduce cutting speed, increase the number of cutting, using high hardness, wear-resistant hard alloy or Xu layer blade.

The top of the thread has burrs to increase the cutting speed, and the workpiece is clamped for machining by the automatic centering principle with the cutting center chuck 4.

Then tighten the chuck to clamp the workpiece.

The vehicle generation completely meets the requirements of the bearing bracket, ensuring the dimensional accuracy and positional accuracy, and saving the workpiece marking and correction, ensuring the quality, and improving the work efficiency by 1.8 times.

For the bearing brackets with different center heights, the horn can be adjusted, but it needs to be fastened with bolts.

Balance adjustment is required before use to avoid centrifugal force affecting the quality of the workpiece and the pressure plate on the equipment.

The size of each part of the main body can be determined according to the size of the bearing bracket. The book is edited by China National Machine Tool Corporation Beijing Guoji Exhibition Center, which brings together products of more than 500 companies, 1717 pages, 16 pages, two volumes, including: Volume: Metal cutting Machine tools; the next volume: forging machinery, casting machinery, woodworking machinery, machine tool attached to the top of the blade.

Parts, CNC systems and machine tools. The price is 350 yuan (including the mail chip is not easy to control to reduce the cutting speed, adjust the feed mode, use the improved side feed cutting, increase cooling.

fee). If you want to purchase, please contact Yu Jiahong, Information Service Department of China National Machine Tool Corporation, No. 19, Beijing Neifang Fangjia Hutong, F. Postcode: 100007, Tel: (010)64017S32-,

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