Cryogenic treatment method of forged steel cold rolling roll and its new nozzle

Abstract

The invention discloses a cryogenic treatment method for forged steel cold rolling rolls and a novel nozzle adopted therefor. The nozzle has a mounting part and a nozzle head, and the nozzle head is provided with a large nozzle with a diameter of 0.8-1.2 mm and several nozzles arranged in large nozzles. There are small nozzles with a diameter of 0.4 to 0.6mm around the nozzle; the cryogenic treatment method is as follows: ①Put the forged steel cold roll in the cryogenic box and close the cryogenic box; ②Spray liquid nitrogen from the nozzle into the cryogenic box, and Reduce the temperature in the cryogenic box to ‑160 to ‑120°C for 1 to 2 hours; ③ keep warm at this temperature for 2 to 5 hours; ④ after the heat preservation is over, open the cryogenic box and place the forged steel cold roll at room temperature , naturally returned to room temperature. By designing a new type of nozzle and matching the corresponding cryogenic treatment method, the present invention can make the ejected liquid nitrogen more dispersed and more uniform, so that the surface hardness of the forged steel cold rolling roll is more uniform, and the hardness of the finished product is uniform, and the phenomenon of nozzle clogging is also decrease very much.

Description

technical field [0001] The invention belongs to the technical field of cryogenic treatment, and in particular relates to a method for cryogenic treatment of forged steel cold rolling rolls and a novel nozzle adopted therefor. Background technique [0002] The forged steel cold roll is the most important part of the cold rolling mill. Most of the cold rolls will be subjected to cryogenic treatment during the manufacturing process. It is an extension of the cooling process of the cold roll heat treatment. The cryogenic treatment is to place the cold roll at a specific low temperature. Change the microstructure in the environment to achieve the purpose of improving the comprehensive performance of cold rolling rolls. [0003] At present, the cryogenic treatment of forged steel cold rolling rolls mainly adopts the direct spraying method of liquid nitrogen. The cryogenic treatment equipment mainly includes: liquid nitrogen storage tanks, cryogenic boxes, liquid nitrogen nozzles a...

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Problems solved by technology

[0004] At present, the problem existing in the liquid nitrogen direct spray cryogenic treatment method is that the hardness uniformity of the finished product is poor. After a lot of research, the applicant found that this problem has a lot to do with the existing structure of the liquid nitrogen nozzle.

The liquid nitrogen ejected from this nozzle is relatively concentrated, and the cooling intensity is relatively high, which will cause the temperature of the local area of ​​the forged steel cold roll to be low, resulting in soft bands or even cracks, and it is also prone to nozzle clogging

[0006] Chinese patent document CN103468918A installs a net cover at the nozzle of the liquid nitrogen nozzle so that the sprayed liquid nitrogen is in the form of a fine mist. However, this technical means cannot solve the above problems well.

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