Views: 64 Author: Site Editor Publish Time: 2022-04-11 Origin: Site
With the continuous development of manufacturing industry, the application of hard-to-process materials with high hardness, high wear resistance, high heat resistance and high chemical stability is increasing.
In order to solve the problem of poor machining performance and difficulty of machining parts of difficult-to-machine materials, the application of various new tool types such as carbide coated tools, diamond, ceramic, cubic boron nitride and other superhard tools is becoming more and more widespread. Through further theoretical research and processing practice, it is proved that: choosing suitable tool material, determining reasonable tool geometry parameters, optimizing and improving the structure of the tool, and choosing the correct processing method are effective ways to improve the processing efficiency of the tool in processing high hardness materials.
Characteristics of high hardness materials.
Common high hardness materials are: chilled cast iron, hardened steel, powder metallurgical materials and other special materials. The processing characteristics of high hardness materials.
1, high hardness (generally above HRC45, some can be as high as HRC68), high strength, low plasticity.
2, the cutting edge is easy to crumble, wear, cutting chips and cutting edge contact short, cutting force and cutting heat concentrated in the tool near the edge, easy to make the cutting edge crumble and wear.
3, low thermal conductivity, cutting heat is difficult to take away through the chip, so the cutting force is large, cutting temperature is very high, the tool wear is serious, easy to cause the knife or broken edge.
4, in addition, in the processing of cold hard cast iron, the edge of the workpiece is also easy to crumble, flaking.
When cutting such materials, if the cutting fluid cooling, may make the tool to bear the intermittent heating - cooling caused by thermal shock, the temperature of the violent changes are likely to cause the carbide cutting edge shattering. On the contrary, if compressed air is used for cooling, it can not only keep the temperature of the tool constant, but also blow the chips away from the cutting area to avoid damage to the tool due to the secondary cutting effect of the high hardness chips.
To achieve cutting processing of high hardness materials, the tool hardness must be much higher than the hardness of the material to be cut. In addition, due to the cutting of high hardness materials, the temperature of the cutting head is very high, so the cutting tool also needs to have the following characteristics.
1. high resistance to plastic deformation, i.e. good high temperature hardness.
2. good chemical stability, i.e. no chemical reaction with the material to be cut, oxygen, cutting fluid, etc., and no thermal decomposition phenomenon.
3. good thermal conductivity, that is, the high-temperature tool head will not be defective due to thermal shock.