Cutting heat and cutting temperature
When cutting metal, the work done due to chip shear deformation and the work done by the friction of the rake and flank faces of the tool are converted into heat, and this heat is called cutting heat. Although the heat of cutting is low to the tool, the temperature on the rake and flank flanks affects the cutting process and the wear of the tool. The cutting edge and cutting temperature have an important impact on tool loss, tool life and thermal deformation of the machining process system.
(1) Causes of cutting heat Under the action of the tool, the metal to be cut undergoes elastic and plastic deformation and consumes work, which is an important source of cutting heat. In addition, the friction between the chip and the rake face, and between the workpiece and the flank face, is also energy-consuming and generates a lot of heat. Therefore, there are three heating areas during cutting, namely the contact area between the shear surface, the chip and rake face, the contact area between the flank face and the transition surface, and the three heating areas correspond to the three deformation zones. Therefore, the source of cutting heat is the chip deformation work and the friction work of the rake and flank faces. When cutting fluid is used, the cutting heat on the tool, workpiece and chips is mainly carried away by the cutting fluid; When cutting fluid is not used, the cutting heat is mainly carried away or transferred from the chips, workpieces and tools, with the chips taking the most heat.
(2) Factors affecting cutting heat and cutting temperature
1) The influence of cutting amount on cutting heat. Cutting speed" has the greatest impact, "doubling the cutting temperature increases the cutting temperature by 32%; The effect of feed f is second, "Doubling the cutting temperature by 18%; The amount of back eating knife a has the least impact,". Doubling the cutting temperature by 7%. The main reason for these laws is the cutting speed. Increase, the friction between the tool and the chip increases dramatically; Back to eat the amount of knife. Increase, although the deformation and friction increase, but the heat dissipation conditions are significantly improved.
2) The influence of the workpiece material. The workpiece material mainly affects the cutting temperature through hardness, strength and thermal conductivity.
The hardness and strength of the material are low, the thermal conductivity is high, and the cutting temperature is low. 3) The influence of the geometric angle of the tool. Increasing the rake angle Y can reduce deformation and friction, and reduce the cutting temperature. y. If it is too large and reduces the volume of the cutter head, the heat dissipation will also be worse. Practice shows that the rake angle y=15° is the most effective for reducing the cutting temperature: the entering angle κ decreases, the cutting deformation and friction increase, and the cutting heat increases, but the cutting temperature decreases because the volume of the cutter head increases after x, and the heat dissipation is greatly improved.
4) The effective pouring method of cutting fluid is a very important measure to reduce the cutting temperature.
