Impeller brazing method
The present invention relates to an impeller manufacturing method in which a thermal cycle is performed on an assembly body with a brazing material formed of a Ni-containing Au alloy being placed at a bond portion of at least two impeller constituent members. The thermal cycle includes a temperature increasing process with a temperature increasing rate of 20° C./hr. to 100° C./hr., the process including a first intermediate retention and a second intermediate retention each keeping the temperature, the first intermediate retention performed in a temperature range of 500° C. to 850° C. and the second intermediate retention performed in a temperature range of 850° C. to 950° C. (but not including 850° C.). In the thermal cycle, the temperature is increased in a temperature range exceeding 950° C. after the second intermediate retention at a rate lower than that before the second intermediate retention.
1. An impeller manufacturing method in which a thermal cycle is performed, for bonding, on an assembly body with a brazing material interposed at a bond portion between at least two impeller constituent members, wherein
the thermal cycle includes:
a temperature increasing process of increasing a temperature to a retention temperature;
a retaining process of retaining at the retention temperature in a temperature range equal to or higher than a melting temperature of the brazing material; and
a temperature decreasing process of decreasing the temperature from the retention temperature to a room temperature, and
the thermal cycle is performed with the assembly body being placed with respect to a first heating body heating the assembly body from an inner circumferential side of the assembly body,
wherein, in the temperature decreasing process, a retention is performed in a temperature range of 930° C. to 970° C. for 0.5 to 2 hours,
wherein the first heating body is configured to protrude from a shaft hole of the assembly body such that the first heating body is heated by directly receiving heat generated externally,
wherein the first heating body is integrally provided together with a second heating body supporting the assembly body from below in a vertical direction, and
wherein the first heating body and the second heating body are configured to be a heating jig that is made of a carbon, the heating jig heated by heat generated externally.
2. The impeller manufacturing method according to claim 1 , wherein the first heating body satisfies 0.5 h 2 ≦h 1 ≦20h 2 , where h 1 is a height of the first heating body and h 2 , is a height of the assembly body.
3. The impeller manufacturing method according to claim 1 , wherein the first heating body satisfies h 2 ≦h 1 ≦10h 2 , where h 1 is a height of the first heating body and h 2 is a height of the assembly body.
4. The impeller manufacturing method according to claim 1 , wherein a size of the first heating body in a diameter direction is configured to satisfy 0.4R 2 ≦R 1 <R 2 , where R 1 is a diameter of the first heating body and R 2 is a diameter of a shaft hole of the assembly body.
5. The impeller manufacturing method according to claim 1 , wherein a size of the first heating body in a diameter direction is configured to satisfy 0.8R 2 ≦R 1 <0.95R 2 , where R 1 is a diameter of the first heating body and R 2 is a diameter of a shaft hole of the assembly body.
6. The impeller manufacturing method according to claim 1 , wherein the second heating body is disk-shaped, and is configured to have a diameter equal to or larger than an outside diameter of the assembly body.
7. The impeller manufacturing method according to claim 1 , wherein a spacer is interposed between the second heating body and the assembly body.
8. The impeller manufacturing method according to claim 1 , wherein, in the temperature decreasing process, the retention is performed at a temperature of approximately 950° C.