Application of domestic hard alloy spiral end mill in machining center
End mills for CNC machining centers are available in a wide range of sizes, from integral alloy end mills to indexable carbide end mills (including modular) and welded carbide end mills 3 class. Classes 1 and 2 have a wide range of uses, while Class 3 spiral end mills have a narrow surface and are not used much. The spiral end mill is analyzed below.
The domestic spiral end mill has been published since the 1980s. At that time, due to the spiral shape of the blade, the process was complicated and difficult, and the production was delayed. Afterwards, the country developed a ministry. There are dozens of professional tool factories that produce spiral end mills with complete specifications. In the past, spiral end mills were used in common milling machines and were used in CNC machining centers. Conventional spiral end mills can cause many disadvantages if they are not properly designed in terms of hard alloy material, blade cross-section dimensions, tool geometry parameters, and tool body strength. The end mill of this structure has its unique advantages, not only the manufacturing process is simple, the cost is low, the most important is the good cutting performance, the cutting edge is sharp, the cutting edge can be repaired many times after being blunt, and the tool is low in cost. It can make up for the shortage of indexable tools in use. If the strength of the tool can be improved and the wear resistance of the tool is increased, such tools are ideal tools.
1. Improvement of spiral end mill
In 1998, Zhuzhou Diamond tried to improve the spiral end mill. The material of the hard alloy blade was changed from the original single YG8 grade to the sub-fine particle YL10.2 and YS25 alloy grade. YL10.2 alloy hardness ≥91.8HRC, bending strength of 4 000N / m2, is mainly suitable for cutting all kinds of cast iron, non-ferrous metals and non-metallic materials. YS25 grade is based on WC-CO-TiC, adding 8% Tac element, corresponding to the scope of ISO P25 ~ P30, mainly used for milling all kinds of steel, especially alloy steel and other materials. Compared with common cemented carbide insert materials, these two alloy materials have greatly improved and improved physical and mechanical properties and performance, and have strong wear resistance, impact toughness, oxidation resistance and anti-adhesion. And anti-diffusion ability; at the same time increase the cross-section size of the spiral carbide insert, the cutter body is quenched, and the tool tip is changed from the original chamfer to the small arc. The improved end mill was used by Suzhou Sodick Sanguang for many years in the pentahedron gantry machining center and received favorable comments. The f50mm new spiral end mill can completely replace the "Sumitomo" same size milling cutter imported from Japan. Its price is 1/4 of the imported knife. Its cutting durability, precision of machined parts and surface roughness are not inferior to those in Japan. Famous brand cutters.
2. Guide rail end mill
On the basis of improving the strength and durability of the spiral end mill, it is only necessary to change the geometrical parameters of the tool to solve the technically difficult finishing. The following describes the newly developed "railway end mill" for the fine-milling guide rail (see the figure). 1). This tool was jointly developed by the author and Tian Runke High-tech, and the tool was manufactured by Zhuzhou Huaxin Carbide Tool Factory.
As we all know, precision machine tools such as EDM wire, EDM machine and CNC machining center, etc., the machine's main large bed, column and carriage are equipped with linear guides with very high precision. The fixed linear guides are two. Two sets of finishing reference planes perpendicular to each other, commonly known as side rails and flat rail faces (see Figure 2), usually two sets of rail faces are 1.1 to 1.5 m long, straightness is 0.005 mm, parallelism is 0.005 mm, and flatness is 0.008. Mm, surface roughness value Ra = 0.8 to 1.6 mm. The processing difficulty and precision are very high. In order to ensure the accuracy of the company, in addition to the selection of high-precision working machines (such as high-precision gantry milling such as Daxie and Mazak), imported hard alloy end mills are also used in the tool configuration. Imported indexable end mills for cutting, so that not only the cost of the tools is expensive, but also the quality of the processing guide rails fluctuates greatly. It is often necessary to manually scrape the scraps to correct or repair the gantry guide grinders. Some companies try to use domestic hard alloy standard spiral end mills. The knife is used to machine the guide surface, but the precision can't be done. It is often necessary to interpolate the program to improve the precision of the working surface. Some large and medium-sized machine tools directly use the CNC gantry guide grinding machine for fine grinding, so that the processing cost is higher. Therefore, finishing high-precision rail surfaces has become a bottleneck for many companies.
The carbide guide fine milling cutter is greatly improved on the basis of the standard spiral end mill. Although the shape is the same, the cutting effect is obviously different. The main improvements are as follows:
(1) Conventional standard spiral end mills, regardless of domestic and foreign products, the cutters are made of dense tooth structure, such as f50mm conventional standard milling cutter z=6, fine milling guide milling cutter z=8~10, so that the number of teeth processed at the same time increases. The cutting is stable.
(2) The geometrical parameters of the tool are changed, the helix angle is different, the 1 blade is 25°, and the adjacent 1 blade is 30°; the end face paying surface (commonly known as the knife gap angle) is reduced and the end face trimming blade is improved. The side cutting edge has a white blade of 0.07 mm and the surface roughness needs to be mirrored.
(3) The cutting head length of the cutting head is shortened, taking 1/2 of the tool diameter and the quenching hardness of the body is 58-60HRC. Rail spiral end mills have been used in Suzhou Sanguang Technology Co., Ltd., Suzhou Wanli Precision Machinery, Jiangsu Suling Precision Machinery, Suzhou Daqi Machinery Co., Ltd. and Changzhou Xinrui for many years, and have achieved good results. See Suzhou for details. The cutting comparison table provided by Sanguang Group (see attached table). The guide rail spiral end mill has been patented and has been authorized by the National Knowledge Industry Bureau in 2014.
Cutting test conclusion: Compared with the previous specifications of cemented carbide milling cutters, the 8-blade new carbide end mills not only improved tool durability by 2 times, but also increased production efficiency by 11% and 38% respectively.
The guide rail spiral end mill is suitable for processing parts with difficult rigidity and high precision machining process due to the sharp cutting edge, stable cutting and high durability. For example, Jiangsu Suling Precision Machinery undertakes a processing task of a famous German company. The Y-axis, Z-axis and column in the three-coordinate measuring instrument are thin-walled frame castings (see Figure 3). The German office in Shanghai used to In Jiangsu and Zhejiang provinces, many powerful mechanical factories have been found to process, but all of them are easy to vibrate due to thin walls, resulting in less precision in milling. Jiangsu Suling Precision selected the guide spiral end mill, which easily processed the above-mentioned difficult-to-machine parts of the company. The inspection accuracy was qualified and the workpiece was sent directly to Germany for assembly.
The spiral end mill can also mill composite materials, such as the printed circuit boards of some instrumentation factories. The bottom plate of the circuit board is a glass laminate covered with a thin non-ferrous metal line, and when the oblique socket of the printed circuit board is milled, With the general milling cutter, the metal circuit and the bottom plate are torn due to the large cutting force, and the tool is passivated very quickly. The spiral end mill with the guide rail can solve this problem smoothly, the work quality is stable, and the tool life is long.
3. Conclusion
The improved spiral end mills have unique advantages in finishing and semi-finishing on the CNC machining center, which can change the tool structure and parameters as well as rough milling.
The domestic hard spiral end mill is a cost-effective tool with good cutting performance and use value in the CNC machining center.
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