Carbide tool model

1. Hardness and strength of carbide cutting tools

Hardness refers to the elastic limit of the metal, and its value is related to the composition of the alloy, processing conditions and use methods.

Generally take HV10H (Shorwitz alloy) as an example, when its hardness value is HV50, the corresponding elastic limit is 1σ. As the amount of cobalt increases, the strength and hardness increase. When the cobalt content is 5%~20%, the strength is higher. When 25%~50%, the hardness is the highest; After more than 50%, the strength decreases.

Generally, when the use temperature is higher than 800 ° C, the metal material begins to embrittlement.

2. Main parameters of carbide cutting tools

The main parameters include hardness, elastic limit, hardenability and wear resistance.

1. Hardness: Taking HRC40-60 as an example, when the hardness is HRC45-50, it refers to the amount of elastic deformation in the metal material, that is, the elastic limit of the alloy. The main parameters of the cobalt carbide blade are: hardness: A120-40, D25-30 as an example. HV50, which corresponds to the elastic limit of 0.35±0.01σ (-0.1) σ; Hardness of cobalt carbide blade: HV50-570, which corresponds to the elastic limit of 0.04±0.02σ; The strength and hardness of the cobalt carbide blade are more than 2 times higher than that of HV50.

2. Elastic limit: Take D25-30 as an example.

3. Processing technology of carbide cutting tools

Carbide blade hardenability determination: at room temperature, with 10℃/min cold oil flow into the carbide blade, measured hardness of 50 HRC. After quenching, the surface of the carbide blade is smoothed with a grinder or a grinding wheel, and then the workpiece is quenched in the furnace at 500 ° C ~600 ° C. There are a lot of residual hardened layers in the workpiece that can not be smoothed and should be removed, otherwise it will affect the service life of the tool. After sintering at 1000~1500℃ for 20 min, after quenching (temperature is 1000℃) treatment, then grinding. Grinding, deburring and other processes should be carried out after grinding.

4. Use and maintenance of cemented carbide tools

1. Cutting quantity

Carbide blade in grinding processing, should be strictly in accordance with the requirements of the appropriate cutting amount. If the ordinary turning tool is used, the chips will be pulled off due to the cutting force; If high speed turning tool is used for grinding, the chip will collapse due to the impact and vibration of the chip moving at high speed. If the workpiece is processed with carbide blades, it is necessary to choose large and high-precision tools and tool bars as far as possible, and use high-speed steel tools, and appropriately increase the flow rate of coolant; In the processing, try to use low speed cutting (such as no-load operation). In addition, the following points should be noted:

2. Remove the chips on the back and tip of the knife in time during processing; 2. Try not to wash the tool directly with water on the workpiece, so that the residual liquid is easy to adhere to the tip of the tool and the back of the tool; 3. When the carbide blade cracks, the blade should be replaced in time; 4. The tool life is increased with the extension of the use of time, in order to extend the tool life can be appropriately increased hardened layer thickness or carburizing process to improve its wear resistance.