TECHNICAL FIELD

The present invention relates to a heat treatment device and a heat treatment method, in particular to a continuous heat treatment method and device for an alloy workpiece or a metal workpiece.

BACKGROUND

The Nd—Fe—B rare earth permanent magnet material, which is currently an industrially produced magnet with the highest magnetic energy product, is widely used in the fields of wind power generation, servo motors, household appliance compressors, new energy auto motors, etc., and has the advantages of small size and high efficiency as compared to other magnets.

To obtain a magnet of desired properties, the Nd—Fe—B material is typically subjected to processes such as melting, crushing, pressing, sintering, heat treatment, etc. The heat treatment here includes a first-stage heat treatment and a second-stage heat treatment, typically at 800° C.-950° C. and 400° C.-650° C. respectively.

In the prior art, the Nd—Fe—B material is heat-treated using a single-chamber heat treatment furnace, where heating and cooling occur repeatedly. The heating and the cooling rates are difficult to control, which in turn increases energy consumption. Therefore, it is difficult to produce a Nd—Fe—B material of excellent properties and consistency by using the traditional single-chamber heat treatment furnace. In addition, since the single-chamber heat treatment furnace generally has a cylindrical furnace body, the inner wall of the cylindrical furnace body functions as a heat source, and the materials are mostly three-dimensional stacked in multiple rows, resulting in various distances from the materials at different positions to the heat source; the temperature consistency and uniformity within the furnace are therefore less ideal, which is particularly the case in the temperature difference between the core material and the peripheral material. Such an arrangement of the materials also limits the ability of the single chamber heat treatment furnace to cool down quickly.

SUMMARY

In view of the above problems, the present invention provides a continuous heat treatment device for an alloy workpiece or a metal workpiece, which can improve a cooling rate and production efficiency and improve product consistency.

The present invention adopts the following technical solutions:

A continuous heat treatment device for an alloy workpiece or a metal workpiece, comprising a first heat treatment chamber, a first cooling chamber, a second heat treatment chamber, and a second cooling chamber disposed in sequence by means of airtight devices, as well as a transfer system disposed among the chambers to transfer the alloy workpiece or the metal workpiece; both the first cooling chamber and the second cooling chamber adopt an air cooling system; a cooling air temperature of the first cooling chamber is 25° C. or above and differs from a heat treatment temperature of the first heat treatment chamber by at least 450° C.; a cooling air temperature of the second cooling chamber is 25° C. or above and differs from a heat treatment temperature of the second heat treatment chamber by at least 300° C.; and the pressures of the cooling chambers are 50 kPa-100 kPa.

The present invention adopts separately disposed heat treatment chambers and cooling chambers (adopting an air cooling system) and defines cooling air temperatures for the cooling chambers; a high-temperature material may be rapidly and uniformly cooled down according to a required cooling process after the completion of heat treatment of the material, optimizing the phase composition and distribution of the grain boundary microstructure of the alloy workpiece or the metal workpiece. The air cooling system can implement a forced convection to quickly remove the heat of the material, and can control the cooling rate according to the variable speed of a fan.

In the present invention, the pressures of the cooling chambers are 50 kPa-100 kPa, which is a conventional selection in the industry. The content range described above is therefore not tested or verified in the embodiments.

Another object of the present invention is to provide a continuous heat treatment method for an alloy workpiece or a metal workpiece. The continuous heat treatment method can improve the cooling rate and production efficiency and improve the properties and consistency of the products.

The present invention adopts the following technical solution:

A continuous heat treatment method for an alloy workpiece or a metal workpiece, wherein the method comprises a first-stage heat treatment, a first-stage air cooling treatment, a second-stage heat treatment, and a second-stage air cooling treatment performed in sequence in air-tight chambers, wherein a cooling air temperature of the first-stage air cooling treatment is 25° C. or above and differs from a heat treatment temperature of the first-stage heat treatment by at least 450° C.; and a cooling air temperature of the second-stage air cooling treatment is 25° C. or above and differs from a heat treatment temperature of the second-stage heat treatment by at least 300° C.

It should be noted that any numerical range disclosed in the present invention includes all point values in this range.

