In the process of mechanical processing, it is often encountered that it is difficult to process with standard tools, so the production of non-standard tools is very important for mechanical cutting.
The use of non-standard tools in metal cutting is more common in milling, so this article mainly introduces the production of non-standard tools in milling.
Since the production of standard tools is aimed at the cutting of common metal or non-metal parts with a wide range of surfaces and large quantities, when the workpiece is overheated and the hardness increases, or the workpiece is stainless steel, it is very easy to stick to the knife, and there are also some surface of the workpiece When the geometry is very complex, or the surface to be processed has a high roughness requirement, the standard tool cannot meet the processing needs. Therefore, in the process of processing, it is necessary to carry out targeted design on the material of the tool, the geometric shape of the knife edge, and the geometric angle, which can be divided into two categories: special order and non-special order.
1. Non-specially customized tools mainly solve two problems, size problem and surface roughness problem.
1. Size problem.
You can choose a standard tool with a size similar to the required size, which can be solved by regrinding, but you also need to pay attention to two points: 1) The size difference should not be too large, generally not more than 2mm, because if the size difference is too large, it will It causes the groove shape of the tool to change, which directly affects the chip space and geometric angle; 2) If it is an end mill with an edge hole, it can be reground on an ordinary machine tool, and the cost is low. If it is a keyway without an edge hole The milling cutter cannot be carried out on ordinary machine tools, and needs to be reground on a special five-axis linkage machine tool, and its cost will be higher.
2. Surface roughness problem.
It can be realized by changing the geometric angle of the blade, such as increasing the degree of the front and rear angles, which will obviously improve the surface roughness of the workpiece. However, if the user's machine tool is not rigid enough, the blunt cutting edge may improve the surface roughness instead. This aspect is very complicated, and a conclusion can only be drawn after analyzing the processing site.
2. The tools that need to be customized are mainly to solve three problems, special shape, special strength and hardness, special chip holding and chip removal requirements.
1. The workpiece to be processed has special shape requirements.
Such as lengthening the tool required for processing, adding end teeth to reverse R, or having special requirements for taper angle, shank structure requirements, blade length size control, etc. If the shape requirements of this type of tool are not very complicated, it is actually easy to solve. The only thing to note is that the processing of non-standard tools is more difficult. Therefore, the user should not overdo it if it can meet the processing requirements. The pursuit of high precision. Because high precision itself means high cost and high risk, which will cause unnecessary waste of the production capacity of the producer and its own cost. Click to get free ☞ 10G tutorials on NC turning (milling), ug programming, cad drawing, NC simulation, NC machinery books, etc.
2. The processed workpiece has special strength and hardness.
If the workpiece is overheated, the strength and hardness are high, and the general tool material cannot be cut, or the tool sticks badly. In this case, it is necessary to put forward special requirements for the material of the tool. The general solution is to choose high-grade tool materials, such as cobalt-containing high-speed steel tools with high hardness to cut quenched and tempered workpiece materials, high-quality cemented carbide tools can process high-hard materials, and even Milling instead of grinding. Of course, there are also some special cases. For example, when processing aluminum parts, there is a kind of superhard tool on the market that is not necessarily suitable. Although aluminum parts are generally soft, it can be said to be an easy-to-process product, but super The material used for hard tools is actually a kind of aluminum high-speed steel. This material is indeed harder than ordinary high-speed steel, but when processing aluminum parts, it will cause the affinity between aluminum elements, which will cause the tool to aggravate wear. At this time, if high efficiency is desired, cobalt high-speed steel can be used instead.
3. The processed workpiece has special requirements for chip containment and chip removal.
At this time, fewer teeth and deeper chip pockets should be used, but this design can only be used for materials that are easier to process, such as aluminum alloys.
In the design and processing of non-standard cutting tools, there are many problems that need to be paid attention to: the geometric shape of the cutting tool is relatively complex. During heat treatment, the cutting tool is prone to bending, deformation, or local stress concentration, which should be avoided during design. For parts prone to stress concentration, add bevel transition or step design to parts with large diameter changes. If it is a slender piece with a relatively large length and diameter, during the heat treatment process, it needs to be inspected and straightened every time it is quenched and tempered to control its deformation and runout. The material of the tool is relatively brittle, especially the material of cemented carbide, which makes the tool break once it encounters a large vibration or a large processing torque during processing. In the processing of conventional tools, Often it will not cause great damage, because the tool can be replaced if it is broken, but in the process of using non-standard tools, since the possibility of replacement is not high, once the tool breaks, it will cause a series of problems, such as delivery Delay, etc., will cause great losses to the user.
The above are all for the tool itself. In fact, the manufacture of non-standard tools is by no means so simple. It is a systematic project. The experience of the manufacturer's design department and the understanding of the user's processing conditions will affect the design and production of non-standard tools. The processing and testing methods of the manufacturer's production department will affect the accuracy and geometric angle of the non-standard tools. The manufacturer's sales department Repeated return visits, collection of data and information will also affect the improvement of non-standard knives, and these will play a decisive role in the success of the user's use of non-standard knives. Non-standard knives are a special kind of knives produced in response to special requirements. Choosing a manufacturer with rich experience will save a lot of time and energy for the user.
