1. High speed cutting mechanism
High speed cutting refers to the cutting process at a speed much higher than the conventional cutting speed. Therefore, the chip forming process and various phenomena on the contact surface between the tool and the workpiece during high-speed cutting are different from the traditional cutting conditions.
With the increase of cutting speed, the heat transferred into the chip increases, the more heat carried away by the chip, and the less heat transferred into the workpiece and tool. During high-speed cutting, about 80% of the heat is generated by chip deformation, and at the same time, more than 95% of the chip heat is taken away by chips, so the workpiece can basically remain cold, and the machining accuracy of the workpiece is high.
In high-speed cutting, the main forms of tool damage are wear and tear. The damage reason varies with the tool material and workpiece material, mainly due to wear, but some are mainly due to damage, or wear is accompanied by micro chipping edge and damage. With the increase of cutting speed and cutting temperature, the wear mechanism is mainly adhesive wear and chemical wear. In high-speed cutting, the tool wear life is determined based on the relationship between the tool wear life, cutting parameters and cutting conditions.
2. Tool material
Because the contact time between the tool and the workpiece is less and the frequency is high during high-speed cutting, the chip wrinkle can be reduced and the cutting heat can be transmitted to the tool more. Tool material has a great influence on tool life, machining efficiency, machining quality and machining cost. When cutting, the tool should bear the effects of high pressure, high temperature, friction, impact and vibration, so the tool material should have:
(1) Hardness and wear resistance: the hardness of the tool material must be higher than that of the workpiece material.
(2) Strength and toughness: the tool material should have high strength and toughness, so as to withstand cutting force, impact and vibration, and prevent brittle fracture and edge collapse of the tool.
(3) Heat resistance: the tool material has good heat resistance, can withstand high temperature, and has good oxidation resistance.
(4) Process performance and economy: the tool material should have good forging performance, heat treatment performance, welding performance, grinding performance, etc.
3. Tool durability
According to the workpiece materials and processing procedures, the correct selection of tool materials and optimization of cutting parameters are important links to improve the durability of tools and ensure the expected effect of high-speed cutting. In actual production, the best cutting speed and feed speed should be determined through experiments according to the processed materials and process characteristics.