In the process of mechanical processing, it is often difficult to use standard tools for processing, manufacturing non-standard tools is very important. Because the use of non-standard cutting tools in metal cutting is more common in milling, this paper mainly introduces the manufacture of non-standard cutting tools in milling.
Since the purpose of manufacturing standard tools is to cut a large number of general metal and non-metal parts over a large area, the workpiece is made of stainless steel when the workpiece overheats and hardens, the cutting edge is very easy, and the surface of the workpiece is also available. When the geometry is very complex or the roughness of the machined surface is very high, the standard tool cannot meet the machining needs. Therefore, in the process of processing, the tool material, blade shape, geometric Angle and other targets can be designed, can be divided into special orders and non-special orders.
First, non-customized tools mainly solve two problems, size and surface roughness
(a) size problem
You can choose a standard tool of a size similar to your needs, which can be solved by regrinding, but two points should be noted:
1, the size difference is too large, the groove shape of the tool will change, directly affect the chip removal space and geometric Angle, so the size difference is not less than 2mm.
2, if there is no cutter hole cutting machine, with ordinary machine tools can not do, need to use a special 5-axis connecting rod to do. The cost of changing machine grinding is also high.
(2) Surface roughness problem
This can be done by changing the geometrical Angle of the blade. For example, increasing the front and rear angles can significantly improve the surface roughness of the workpiece. However, if the user's machine is not rigid enough, the cutting edge will become blunt and the surface roughness can be improved. This point is very complex and the treatment plant needs to be analyzed before any conclusions can be drawn.
Two, the need to customize the tool is mainly to solve three problems: special shape, special strength and hardness, special tolerance and tip removal requirements
(a) the workpiece has special shape requirements
For example, the machining tool may be lengthened, the end tooth is inverted, and there may be special cone Angle requirements, tool handle structure requirements, blade length size control, etc. If the geometry of such a tool is not very complicated, it is actually quite easy to solve. The only caveat is that non-standard tools are harder to work with. Because high precision itself means high cost and high risk, it will cause unnecessary waste to manufacturers' capacity and their own costs.
(2) the strength and hardness of the workpiece
Workpiece overheating, processing of ordinary tool material is too strong, too hard, or serious tool wear. It needs to be transferred and has special requirements for the material of the tool. The common solution is to choose high-grade tool materials, such as high-speed steel tools with high hardness of cobalt for cutting and tempering workpiece, and high-quality cemented carbide. Machines instead of grinding. Of course, it can also be special. For example, when machining aluminum parts, it may not match the type of carbide tool that is commercially available. Aluminum parts are generally soft, but can be easily processed. The material used for the hard tools is actually aluminum high-speed steel. This material is harder than ordinary high-speed steel, but in the processing of aluminum parts, will cause the affinity of aluminum elements, increase tool wear. At this time, if you want to achieve high efficiency, you can choose cobalt high speed steel instead.
(3) The workpiece has special requirements for blade tolerance and blade disassembly
In this case, a smaller number of teeth and deeper tip slots must be used, but this design can be used in mechanically simple materials, such as aluminum alloys.
In the design and processing of non-standard tool, the geometric shape of the tool is more complex, and it is easy to appear bending deformation, deformation and local stress concentration in the process of heat treatment, which must be avoided in the design. For parts with high stress concentration, add bevel transition or step design for parts with large diameter changes.
If it is an elongated piece with large length and diameter, it needs to be checked and straightened after each fire extinguishing and tempering to control deformation and loss during heat treatment. The material of the tool is more brittle, especially the hard alloy material, if the vibration or processing torque is large, will damage the tool. If broken, the tool can be replaced, but in many cases it will not cause much damage, but when dealing with non-standard tools, the probability of replacement is high, so when the tool is broken, it can cause a lot of damage. Users, including causing delays and other issues.