Motor core production method and heat treatment device used therefor
The present invention relates to a motor core production method including: a preparation step of preparing a laminate of electromagnetic steel sheets each processed into a predetermined shape; a first heating step of heating the laminate at an atmospheric temperature of 500° C. to 800° C. in an atmospheric gas comprising at least one kind selected from the group consisting of a low oxidizing gas and a reducing gas, and having a dew point of −20° C. or lower; and a second heating step of soaking the laminate at 1,000° C. to 1,200° C. in a vacuum of 100 Pa or less after the first heating step, and a heat treatment device for performing the production method.
1 . A motor core production method comprising:
a preparation step of preparing a laminate of electromagnetic steel sheets each processed into a predetermined shape;
a first heating step of heating the laminate at an atmospheric temperature of 500° C. to 800° C. in an atmospheric gas comprising at least one selected from the group consisting of a low oxidizing gas and a reducing gas, and having a dew point of −20° C. or lower; and
a second heating step of soaking the laminate at 1,000° C. to 1,200° C. in a vacuum of 100 Pa or less after the first heating step.
2 . The motor core production method according to claim 1 , wherein the laminate is heat-treated in a state of being placed on a jig made of a C/C composite.
3 . The motor core production method according to claim 1 , wherein the low oxidizing gas is nitrogen gas, and the reducing gas is at least one selected from the group consisting of hydrogen gas and carbon monoxide gas.
4 . The motor core production method according to claim 1 , wherein each of the electromagnetic steel sheets before the first heating step has an average crystal grain size of less than 100 μm.
5 . The motor core production method according to claim 4 , wherein the each of electromagnetic steel sheets after the second heating step has an average crystal grain size of 100 μm to 300 μm.
6 . The motor core production method according to claim 1 , further comprising a degreasing step of evaporating oil content adhering to the electromagnetic steel sheets constituting the laminate,
wherein the degreasing step is performed before the first heating step.
7 . The motor core production method according to claim 6 , wherein the degreasing step comprises heating the laminate at 300° C. to 500° C. in a vacuum of 100 Pa or less.
8 . The motor core production method according to claim 1 , further comprising an annealing step of annealing the laminate after the second heating step.
9 . The motor core production method according to claim 8 , wherein the annealing step comprises cooling the laminate at a predetermined cooling rate.
10 . The motor core production method according to claim 8 , further comprising a rapid cooling step of rapidly cooling the laminate after the annealing step.
11 . The motor core production method according to claim 1 , wherein the atmospheric gas in the first heating step is a mixed gas comprising nitrogen gas and at least one selected from the group consisting of hydrogen gas and carbon monoxide gas.
12 . The motor core production method according to claim 1 , wherein the first heating step comprises heating the laminate at an atmospheric temperature of 600° C. to 750° C.
13 . The motor core production method according to claim 1 , wherein the second heating step comprises soaking the laminate at 1,050° C. to 1,150° C.
14 . The motor core production method according to claim 1 , wherein the atmospheric gas in the first heating step has a dew point of −30° C. or lower.
15 . The motor core production method according to claim 1 , wherein the vacuum in the second heating step is 10 Pa or less.
16 . The motor core production method according to claim 1 , wherein the laminate is a rotor core or a stator core.
17 . The motor core production method according to claim 1 , wherein the electromagnetic steel sheets are non-oriented electromagnetic steel sheets.
18 . The motor core production method according to claim 2 , wherein the jig comprises a plurality of sheet-shaped trays and spacers erected at corners of the trays, and wherein a plurality of laminates are placed on each tray.