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Vacuum Heat Treatment Furnace

Vacuum Sintering Furnace

Vacuum Brazing Furnace

Saw Hob Vacuum Furnace Application

Before the vacuum gas quenching furnace is widely used, the heat treatment of high-speed steel generally uses a vacuum oil quenching furnace. Although the vacuum oil quenching furnace treatment solves the problem of surface oxidation of the workpiece, it has the following obvious defects: ①The cooling rate cannot be controlled, so The deformation of the workpiece is large; ②Austempering at a certain temperature cannot be carried out, also called graded quenching; ③Quenching oil can also cause carbonization on the surface of the workpiece, which increases the workload of subsequent grinding. The working principle of the vacuum gas quenching furnace is that after the workpiece is heated in a vacuum environment, the inert gas (usually nitrogen and argon as process gas) is quickly injected into the furnace to make it reach a high pressure state (usually 6-20kg pressure), and Through the cooling circulation system in the furnace body, the process gas flows rapidly on the surface of the workpiece, thereby taking away the heat of the workpiece, allowing the workpiece to cool down quickly to achieve the purpose of quenching.

Compared with vacuum oil quenching, the vacuum high-pressure gas quenching process has the following main advantages: ①The surface quality of the workpiece is good, no oxidation, no carbon increase; ②The cooling speed is relatively uniform during vacuum quenching, and the deformation of the workpiece is small; ③The cooling speed during vacuum quenching The controllability is good, and isothermal quenching can be realized; ④ Vacuum quenching does not require post-cleaning, so there is cleaning agent residue on the surface of the workpiece; ⑤ Quenching gas can be directly discharged or recovered, and the on-site working environment is much better than that of the vacuum oil quenching furnace workshop.
Because the processing and molding of the saw blade hob is more complicated, the processing time is longer, the weight of the hob blank is heavier, and the price of raw materials is relatively high. In order to improve the life of the M42 hob and solve the problems of toughness and wear resistance, the commonly used process is high-pressure gas quenching. Here, a vacuum furnace with a maximum quenching pressure of 10kg produced by SIMUWU Company is used for heat treatment, and an isothermal cooling process is used for testing. Isothermal The advantage of cooling can reduce the possibility of workpiece deformation and cracking, and at the same time can increase the strength and toughness of the workpiece.

Vacuum heat treatment process
Considering that the diameter of the M42 high-speed steel raw material is large and the carbide segregation is large, the material is brittle when the hardness is high, so the vacuum heat treatment process adopts the isothermal method for cooling. After different vacuum heat treatment process tests and saw hob cutting performance tests. Reasonable selection of quenching temperature and time, cooling pressure, isothermal temperature and isothermal time, and finally use 1160 ° C for 60 minutes, cooling with 8-9 bar, and isothermal at about 300 ° C for 1 hours, then rapidly cooled to room temperature, and then tempered three times at a high temperature of 550°C.

M42 saw blade hob vacuum heat treatment test
The material to be processed is alloy spring steel X32 with a thickness of 1.6mm. The hobbing depth is 8mm. Continuous cutting can achieve a cutting life of 25,000-30,000 meters. The life is about doubled.

Discussion and Analysis of Saw Hob Vacuum Furnace Technology
The so-called hardenability is also the cooling rate. Here, aside from many complicated principle formulas, the cooling rate is related to the three factors of the processed charge, cooling medium and equipment.
(1) Factors of the charge to be processed: charging weight, charging method, workpiece material, workpiece size, workpiece shape, workpiece structure, etc. (2) Cooling medium factors: type of cooling gas, high-speed steel routinely chooses practical and cheap nitrogen . (3) Equipment factors: gas pressure, gas flow and velocity, and heat transfer capacity of heat exchangers. Different furnace types, when the factor of the furnace material to be processed and the factor of the cooling medium can be consistent, the most influential factor is the equipment factor. The quenching pressure used this time is only 8-9 kg (the designed quenching pressure of the furnace is 10 kg), which is far lower than the conventionally recognized pressure quenching of 13-15 kg or more, but the process test results are still very satisfactory.