JPS6127597B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention The present invention relates to an impeller for a centrifugal pump, an aeration device, etc., and a method for manufacturing the impeller.

As is well known, impellers used in centrifugal pumps, aeration equipment, etc. are required to have excellent wear resistance for the impeller disc and vane plate portion, while the boss portion is required to be easily post-processed, such as by grinding. This is necessary.

However, in the past, the impeller disk and vane plates were formed by pouring molten metal into a mold in which the boss was supported internally and a space was provided around it. Therefore, a metal having a lower melting temperature than the impeller disc and vane plate cannot be used for the boss part. Metals with high melting temperatures are also hard and difficult to process. The material used for the impeller is usually chrome steel, but as it is hard and difficult to grind, the cast impeller is first annealed and then the end face and inner circumference of the boss are ground. After finishing the material to the desired dimensions, it is re-quenched and the resulting distortion is removed by grinding, which is an extremely complicated process.

The object of the present invention is to mold parts that do not require post-processing from a hard material with high wear resistance, and mold parts that do not require post-processing from a relatively soft material that is easy to post-process. The objective is to supply impellers with high durability and precision at low cost.

(2) Structure of the Invention In the impeller according to the present invention, the impeller disk and the impeller plate are arranged on the circumferential side of the boss portion, which is compression-molded by melting a metal that is softer and has a lower melting temperature than the impeller disk and the impeller plate. The inner circumferential edge of the wheel disc engages, or a locking piece protruding from a key point on the inner circumference of the impeller disc engages, thereby integrally joining the boss part. In addition, in the method for manufacturing an impeller of the present invention, the impeller disk and the impeller plate are supported in a predetermined mold, and a space portion having the same shape as the circumferential side of the boss portion described later is formed in the center of the impeller disk and the impeller plate. A metal that is softer and has a lower melting temperature than the disc and vane plate is melted and injected into the space, and then compressed in the axial direction by a forging mold to form the boss part and into the circumference thereof. By engaging the inner peripheral portion of the impeller disk, the boss portion is integrally connected to the impeller disk and the blade plate.

The drawings of the embodiment will be explained below. In FIG. The boss portion 3 is required to be made of a metal having a higher melting temperature than the boss portion 3, and is made integrally by casting from a hard material such as chrome steel. The boss portion 3 is required to be made of a metal having a lower melting temperature than the impeller disc 1 and the vane plate 2, and is compression molded by melting a relatively soft material such as gunmetal.

For melting and compression molding the boss portion 3, a mold 4 as shown in FIG. 3 is used. The mold 4 includes a lower mold 4a on which the impeller disc 1 and the vane plate 2 are placed, and a lower mold 4a that fits over the lower mold 4a to cover the impeller disc 1 and the vane plate 2, and a central part of the mold 4. It consists of an upper mold 4b that forms a predetermined space 5, and a forging mold 4c that is press-fitted into the space 5 through a hard hole 6 of the upper mold 4b. A sprue 7 that communicates into the space 5 through the hard hole 6 is bored in the part. Then, the impeller disc 1 and the blade plate 2, which were cast in advance and made integrally as shown in FIGS. 2A to 2C, are supported on the lower mold 4a, and then the upper mold is molded as shown in FIG. 3A. 4b and into the space 5 formed by joining them together, a molten liquid such as gunmetal is poured from the sprue 7 as shown in Figure B, and then the forging mold 4c is lowered through the hard hole 6 as shown in Figure C. to compress it in the axial direction. Then impeller disk 1
The gap g that had been generated near the inner circumferential portion of the impeller disk 1 is gradually eliminated, and the inner circumferential edge 1e of the impeller disk 1 is firmly attached to the circumferential side of the boss portion 3. Then, the impeller taken out from the mold 4 has a shaft hole 3h bored in the center of the boss part 3, an end face part 3x and an inner periphery 3.
It can be finished to the required dimensions by grinding y.

As described above, the inner circumferential edge 1e of the impeller disc 1 enters into the circumferential side of the boss portion 3 which is compressed in the axial direction within the space portion 5, and the inner circumferential edge 1e of the impeller disk 1 is inserted into the boss portion 3, and the inner circumferential edge 1e of the impeller disc 1 is joined together as shown in FIG. The impeller is constructed as shown in FIG. 1. In order to prevent slippage at the joint between the boss portion 3 and the impeller disk 1 when the impeller rotates, locking pieces 1f are provided at key points on the inner circumference of the disk. When the locking pieces 1f are made to protrude, rather than simply protruding in the centripetal direction, the locking pieces 1f are tilted or curved vertically as shown in Figure 2B, or twisted in an oblique direction as shown in Figure 2C. If it is curved, the locking effect can be significantly increased, and even if there are some gaps g left on the front and back of the locking piece 1f and on the circumferential side, the joint part will not wobble. There is no.

(3) Effects of the Invention According to the present invention, the impeller disc 1 and the vane plate 2, which do not require post-processing, are made of a hard material with high wear resistance and have excellent durability. boss part 3 that requires post-processing.
Since it is made of a metal that is softer and has a lower melting temperature than the impeller disk 1 and the vane plate 2, the boss end face 3x and inner circumference 3y can be ground without the need for annealing as in the conventional case. can be administered. In addition, as a result of not requiring annealing work for post-processing the boss portion 3, there is naturally no need for re-hardening.
Therefore, since no distortion occurs in the impeller disc 1 and the impeller plate 2, it is possible to obtain a highly accurate impeller without the need for polishing to remove distortion, which is extremely rational and easy to manufacture. This will significantly reduce costs. Moreover, unlike impellers manufactured by conventional methods, the inner peripheral part of the impeller disc 1 is inserted into the boss part 3 so as to wrap around it. Coupled with the fact that the locking piece 1f on the circumferential portion can be formed in various forms, the connection between the boss portion 3 and the impeller disc 1 can be made extremely strong.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of the impeller of the present invention, and FIG. 2 is a diagram illustrating the manner in which the locking pieces protrude from the inner periphery of the impeller disc of the impeller of the present invention, where A is the locking piece. B is a plan view showing an example in which the locking piece is extended straight in the centripetal direction, B is a longitudinal side end view showing an example in which the locking piece is protruded in a bent shape, and C is an example in which the locking piece is curved in a spiral shape. FIG. 3 is a vertical side view showing one process of manufacturing an impeller by the method of the present invention, and A shows a state in which the impeller disc and blade plate are supported in the mold. , B shows the state in which the metal for forming the boss part is melted and injected into a predetermined space in the mold, and C shows the state in which the forging mold is lowered onto the injected molten metal to perform compression molding. Indicates the state in which it is applied. 1... Impeller disc, 1e... Inner peripheral edge, 1f...
Locking piece, 2... Feather plate, 3... Boss portion, 4... Mold, 4e... Forging mold, 5... Space portion.

Claims (1)

[Scope of Claims] 1. The inner circumferential edge of the impeller disk is engaged within the circumferential side of a boss portion that is compression-molded by melting a metal that is softer and has a lower melting temperature than the impeller disk and the impeller disk. An impeller characterized in that the impeller is integrally connected to a boss portion. 2. Projected from key points on the inner periphery of the impeller disk within the periphery of a boss portion formed by melting and compression molding a metal that is softer and has a lower melting temperature than the impeller disk and vane plate. An impeller characterized in that a locking piece engages and is integrally combined with a boss part. 3. The impeller disc and the vane plate are supported in a predetermined mold, and a space having the same shape as the circumferential side of the boss part described later is formed in the center thereof, and is softer than the impeller disc and the vane plate and has a melting temperature. After melting a metal with a low temperature and injecting it into the space, compression is applied in the axial direction using a forging mold to form the boss part, and the inner peripheral part of the impeller disk is inserted into the peripheral side of the boss part. A method for manufacturing an impeller, characterized in that the boss portion is integrally coupled with the impeller disk and the blade plate by doing so.