JP2012176417A - Method for manufacturing impeller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an impeller that can enhance working efficiency while avoiding an increase in cost, and also can obtain a high-strength impeller.SOLUTION: The method for manufacturing an impeller includes a forging step of subjecting an outer circumferential region 16 that is a predetermined range from an outer circumferential side toward a radially inner side of an inclined curved surface 12 of an impeller material 11, to forge processing using molds 21, 21 corresponding to a flow path, sequentially in a circumferential direction of the material to form a groove 13 in a part to be formed into the flow path and also to form a raised part 14 in a part to be formed into a blade.

Description

  The present invention relates to an impeller manufacturing method in which a hub and a blade are integrally formed from a base material.

An impeller used in a rotary machine such as a centrifugal compressor is formed by welding a hub fixed to a rotary shaft, a plurality of blades protruding from the surface of the hub, and a shroud covering the upper side of the blade to each other. It is common to be manufactured.
However, in the impeller manufacturing method in which the three members are welded to each other in this way, when the flow path formed between the blades is narrow, it is difficult to insert and operate the welding torch into the flow path. There is a problem that this defect is easily generated.
In addition, since the three members are welded together, there is a problem that the number of locations where the deformation occurs due to high temperatures locally due to an increase in the number of weld locations.

  As a means for solving such a problem, the hub and the blade are integrated from the impeller material by using a mill tool having a blade provided at the tip and cutting the flow path in the impeller material as a base material. A method of manufacturing an impeller to be cut out is known.

  In addition, Patent Document 1 proposes a method of manufacturing a titanium impeller by forging. According to this method, the entire base material made of titanium is forged to form a shape close to the final product, that is, a shape having a hub and a blade as a prototype, and then a machine is formed in these prototype portions. By processing, an impeller as a final product including a hub and a blade is obtained.

JP 2005-48769 A

However, the impeller manufacturing method using the mill tool has a problem that it takes a long time to integrally cut the hub and the blade from the impeller material, and the working efficiency deteriorates.
In addition, as shown in Patent Document 1, in the impeller manufacturing method using forging, the strength of the base material structure can be improved by forging, so that the strength can be improved. There is a concern that the manufacturing cost will increase due to an increase in the amount of consumption and the number of man-hours.

  The present invention has been made in view of such problems, and an impeller manufacturing method capable of improving work efficiency while avoiding an increase in cost and capable of obtaining a high-strength impeller. The purpose is to provide.

In order to solve the above problems, the present invention provides the following means.
That is, in the impeller manufacturing method according to the present invention, a plurality of blades extending in a radial direction are provided on a disc-shaped hub at intervals in the circumferential direction, and a flow path is formed between adjacent blades. A manufacturing method comprising: forming a base material having an inclined curved surface that gradually slopes toward one end side from a disk-shaped member made of carbon steel; and extending from the outer peripheral side of the inclined curved surface toward the radially inner side. For each outer peripheral side region that is a predetermined range, a forging process using a mold corresponding to the flow path is sequentially performed in the circumferential direction, thereby forming a groove portion in a portion that becomes the flow path and the blade A forging step for forming a rising portion in a portion to be formed, and cutting the inner circumferential side region radially inward of the groove portion, the rising portion and the outer peripheral side region of the base material, the hub, The blade and Characterized in that it comprises a finishing step of forming a serial flow path.

According to the impeller manufacturing method having such characteristics, a groove and a rising portion that become a flow path and a blade are formed by forging only the outer peripheral side region of the base material, not the whole base material. Then, a blade and a flow path are formed by finishing. In this way, by performing the finishing process after forming the general shape of the impeller by forging, it is possible to improve the working efficiency as compared with the case where the base material is cut from the beginning.
Here, when the impeller rotates, the centrifugal force increases toward the outer peripheral side, so that the stress generated inside increases toward the outer peripheral side. Further, since the hub thickness decreases toward the outer peripheral side, the hub rigidity also decreases toward the outer peripheral side. Therefore, on the outer peripheral side of the hub, there is a concern about breakage / deformation due to the influence of the stress.
On the other hand, in the present invention, since the forging process is performed on the outer peripheral side region of the base material, the strength is increased on the outer peripheral side of the base material due to the densification of the structure. Thereby, the intensity | strength which can endure the said centrifugal force is realizable also on the outer peripheral side of a thin hub, and the whole impeller can be made high intensity | strength.
Furthermore, since the forging is performed only on the outer peripheral side region of the base material, the heating energy consumption and the number of man-hours can be suppressed as compared with the case where the entire base material is forged, and an increase in cost can be avoided. . In other words, by forging only the portions that require particularly high strength, it is possible to obtain a high-strength impeller while reducing costs.

  In the impeller manufacturing method according to the present invention, it is preferable that the forging step is performed by a plurality of molds arranged at intervals corresponding to the pitch of the flow path in the circumferential direction.

  According to the impeller manufacturing method having such characteristics, forging can be performed so that the base material is sandwiched between portions between adjacent dies, so that the rising portion formed in the portion between these dies The rising height of can be increased. As a result, the shape of the inclined curved surface of the base material can be made closer to the shape of the final product, so that the subsequent finishing can be easily performed and work efficiency can be improved.

  Furthermore, in the method for manufacturing an impeller according to the present invention, the forging step is performed in a state where an outer peripheral surface of the base material is constrained by a ring-shaped member.

  Thereby, when forging the outer peripheral side region, it is possible to prevent the base material from spreading to the outer peripheral side. Therefore, it can avoid that the outer peripheral side of a preform | base_material becomes thin more than necessary, and a strength falls, and the intensity | strength as the whole impeller can be maintained high.

  According to the impeller manufacturing method of the present invention, the cost is increased by manufacturing the impeller by forging only the outer peripheral side region which is a partial range from the radially outer side to the inner side with respect to the base material. It is possible to improve the working efficiency while avoiding the above, and to obtain an impeller capable of maintaining high strength.

It is a perspective view of the impeller manufactured by the manufacturing method of the impeller of 1st embodiment of this embodiment. It is a perspective view at the time of mounting a disk-shaped member on the table unit regarding the manufacturing method of the impeller which concerns on 1st embodiment of this invention. It is a perspective view explaining a base material formation process about a manufacturing method of an impeller concerning a first embodiment of the present invention. It is a perspective view explaining a forge process regarding the manufacturing method of the impeller concerning a first embodiment of the present invention. It is a perspective view explaining a forge process regarding the manufacturing method of the impeller concerning a first embodiment of the present invention. It is a top view explaining a forge process regarding the manufacturing method of the impeller concerning a first embodiment of the present invention. It is a top view of the impeller material of a forge process regarding the manufacturing method of the impeller which concerns on 1st embodiment of this invention. It is explanatory drawing about a finishing process regarding the manufacturing method of the impeller which concerns on 1st embodiment of this invention. It is a top view explaining a forge process regarding the manufacturing method of the impeller which concerns on 2nd embodiment of this invention.

Hereinafter, an impeller manufacturing method according to a first embodiment of the present invention will be described with reference to the drawings.
The impeller 1 manufactured according to the present embodiment is used for a rotary machine such as a compressor or a turbine, for example, and includes a hub 2 and a blade 3 which are integrated with each other as shown in FIG.
The hub 2 is a substantially disk-shaped member, and one end surface has a small diameter and the other end surface has a large diameter. These two end surfaces are connected by a curved surface that gradually increases in diameter from one end side toward the other end side.

A plurality of blades 3 are provided so as to rise from the curved surface of the hub 2. Each blade 3 extends so as to curve toward one side in the circumferential direction as it goes from the inside in the radial direction to the outside, and in this embodiment, 12 blades 3 are spaced at regular intervals in the circumferential direction. Is formed.
In the impeller 1, a region between adjacent blades 3 on the curved surface of the hub 2 is a flow path 4 through which fluid flows.

Next, the procedure of the method for manufacturing the impeller 1 will be described.
First, an operator performs the impeller material 11 production process. That is, the operator cuts an elongated columnar material made of carbon steel to produce a disk-like member 10 having a substantially circular shape in plan view as shown in FIG.

  Then, as shown in FIG. 2, the operator places the produced disk-shaped member 10 on the upper surface of the table unit 20 that can be driven to rotate around the vertical axis. At this time, the disk-shaped member 10 is placed so that the member on one side of the disk-shaped member 10 contacts the upper surface of the table unit 20.

  Subsequently, the operator rotates the table unit 20 and the disk-shaped member 10, and presses a roll that moves in the radial direction and the axial direction against the rotated disk-shaped member 10, thereby fixing the disk shape on the disk-shaped member 10. A base material forming step for processing the upper outer periphery of the disk-shaped member 10 is performed by pressing a so-called roll mill (not shown) having a blade provided on the outer peripheral surface against the member 10. As a result, as shown in FIG. 3, an inclined curved surface 12 whose diameter is gradually reduced toward the upper end, that is, toward one end, is formed on the upper portion of the disk-shaped member 10, and the impeller material 11 is completed. The impeller material 11 is a base material of the impeller 1 to be manufactured.

  Next, the operator performs a forging process. This forging process is performed by a pair of molds 21 and 21, as shown in FIGS. The molds 21, 21 are disposed above the outer peripheral side region 15 of the impeller material 11 with an interval corresponding to the pitch of the flow path 4 in the circumferential direction. Here, the outer peripheral side region 15 means an annular region in a predetermined range from the outer peripheral side of the inclined curved surface 12 in the impeller material 11 toward the radially outer side, as shown in FIG. . The outer peripheral side region 15 can be set as an annular region in a range of 1/2 to 1/3 of the radius of the impeller material 11, for example.

  Further, the molds 21 and 21 have a plan view shape corresponding to a plan view shape of the flow path 4 of the impeller 1, that is, a shape that fits in the flow path 4 in the plan view. In the present embodiment, the shape of the molds 21 and 21 in plan view is a substantially square shape that widens toward the radially outer side of the impeller member 11, and the overall shape of the molds 21 and 21 is the substantially square shape. It has a shape extending in the vertical direction, that is, in the axial direction of the impeller material 11.

  As shown in FIGS. 4 and 5, in the forging process, the inclined curved surface 12 of the impeller material 11 is moved by moving the dies 21 and 21 up and down while heating the impeller material 11 to, for example, 1000 ° C. or higher by a heating means (not shown). It is performed by applying pressure by the molds 21 and 21 to the mold. That is, the pair of molds 21 and 21 collide with the inclined curved surface 12 from above to apply pressure to the inclined curved surface 12 to deform the inclined curved surface 12. As a result, as shown in FIG. 6, in the outer peripheral side region 15 of the base material of the impeller material 11, the pair of groove portions 13 recessed by the pressure of the pair of molds 21, 21 and the groove portions 13 are separated in the circumferential direction. A rising portion 14 is formed. The groove 13 and the rising portion 14 are portions that finally become the flow path 4 and the blade 3 of the impeller 1.

The rising portion 14 is a portion sandwiched between the pair of molds 21 and 21, and the carbon steel present in the portion that becomes the groove portion 13 when the groove portion 13 is formed by the pressure of the molds 21 and 21. Is formed by gathering between a pair of molds 21, 21.
In addition, the forging by the pair of molds 21 and 21 is performed by intermittently driving the table unit 20 according to the vertical movement of the molds 21 and 21, so that the outer peripheral side region 15 of the inclined curved surface 12 of the impeller material 11. Sequentially applied circumferentially to the entire area. As a result, as shown in FIG. 7, a plurality of groove portions 13 and rising portions 14 are formed at equal intervals in the circumferential direction over the entire outer peripheral side region 15 of the inclined curved surface 12. In the present embodiment, twelve groove portions 13 and rising portions 14 are formed at intervals of 30 ° in the circumferential direction.

  After such a forging process, the operator performs a finishing process on the impeller material 11 in which the groove 13 and the rising portion 14 are formed. This finishing process is performed on the inner peripheral side region 16 (see FIGS. 6 and 7), which is a portion radially inward of the outer peripheral side region 15 of the groove portion 13, the rising portion 14, and the inclined curved surface 12, for example, FIG. As shown in FIG. Thereby, the hub 2 and the blade 3 are integrally cut out from the base material, and a portion between the adjacent blades 3 on the surface of the hub 2 serves as the flow path 4. The operator then polishes the bottom surface of the flow path 4 and the side surface of the blade 3. Thereby, the impeller 1 shown in FIG. 1 is completed.

  According to the manufacturing method of the impeller 1 as described above, the flow path 4 and the blade 3 are obtained by forging only the outer peripheral side region 15 of the impeller material 11 instead of the entire impeller material 11 as a base material. The groove portion 13 and the rising portion 14 are formed, and then the finishing process is performed to form the blade 3 and the flow path 4. As described above, after the rough shape of the impeller 1 is formed by forging, that is, the impeller 1 is manufactured by cutting the base material from the beginning by performing a finishing process after forming the near net shape. Compared to the above, work efficiency can be improved.

  Here, when the impeller 1 rotates in the rotating machine to which the impeller 1 is attached, the centrifugal force increases toward the outer peripheral side, so that the stress generated inside increases toward the outer peripheral side. Further, since the thickness of the hub 2 becomes smaller toward the outer peripheral side, the rigidity of the hub 2 becomes smaller toward the outer peripheral side. As described above, on the outer peripheral side of the hub 2, there is a concern about breakage / deformation due to the influence of the stress due to an increase in centrifugal force and low rigidity.

  On the other hand, in this embodiment, since the forging process is performed on the outer peripheral side region 15 of the impeller material 11, the strength is increased due to the densification of the structure on the outer peripheral side of the impeller material 11. Thereby, the intensity | strength which can endure the said centrifugal force is realizable also on the outer peripheral side of the hub 2 with thin thickness, and the impeller 1 whole can be maintained at high intensity | strength.

  For example, a method of forging the entire inclined curved surface 12 of the impeller material 11 to achieve near shaping can be considered. Resulting in. In this respect, in the present embodiment, by forging only the outer peripheral side region 15 of the impeller material 11 that should be maintained at a high strength, the consumption amount of heat energy and the number of man-hours are compared with the case of forging the entire impeller material 11. Can be suppressed. That is, the forging process is performed only on the portion requiring particularly high strength, so that the high-strength impeller material 11 can be efficiently manufactured while avoiding an increase in cost.

  Further, by performing forging with a pair of molds 21, 21 arranged with a gap between the flow paths 4 in the circumferential direction, the impeller material 11 is sandwiched by a portion between the pair of molds 21, 21. Therefore, the rising height of the rising portion 14 formed in the portion between the molds 21 and 21 can be increased. As a result, the shape of the inclined curved surface 12 of the impeller material 11 can be made closer to the shape of the final product, so that the subsequent finishing can be easily performed and the working efficiency can be improved.

Next, the manufacturing method of the impeller 1 of 2nd embodiment is demonstrated. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
This second embodiment is different from the first embodiment in the method of the forging process. That is, in the second embodiment, as shown in FIG. 9, the forging process is performed in a state where the outer periphery of the impeller material 11 is restrained by the ring-shaped member 23.

The ring-shaped member 23 is an annular member made of, for example, a steel material, and the inner diameter thereof is set to be substantially the same as the outer diameter of the impeller material 11. Further, the thickness of the ring-shaped member 23, that is, the dimension in the axial direction is set larger than the thickness of the outer periphery of the impeller material 11.
The operator externally fits the ring-shaped member 23 to the outer periphery of the impeller material 11 prior to the forging process. As a result, the inner peripheral surface of the ring-shaped member 23 is in close contact with the outer periphery of the impeller material 11 over the entire circumferential direction, and the entire outer periphery of the impeller material 11 is constrained.

  And after fitting the ring-shaped member 23 to the impeller material 11 in this way, the operator drives the table unit 20 intermittently and moves the pair of molds 21 and 21 up and down as in the first embodiment. Thus, the groove portion 13 and the rising portion 14 are formed in the entire circumferential direction of the inclined curved surface 12 of the impeller material 11.

  According to the manufacturing method of the impeller 1 of the second embodiment, the impeller material 11 can be prevented from spreading to the outer peripheral side when the outer peripheral side region 15 is forged. As a result, it can be avoided that the outer peripheral side of the impeller 1 becomes unnecessarily thin and the strength is lowered, and the strength of the impeller 1 as a whole can be maintained high.

  When forging is performed using a pair of molds 21 and 21 as in this embodiment, the amount of deformation of the impeller material 11 due to a single collision of the molds 21 and 21 with the impeller material 11 is single. Since it becomes larger than the case where forging is performed using the molds 21 and 21, the amount of spread of the impeller material 11 outward in the radial direction is also increased, but the disadvantage is avoided by using the ring-shaped member 23. be able to. Therefore, by using the forging by the pair of molds 21 and 21 and the installation of the ring-shaped member 23, the high-strength impeller 1 can be manufactured more efficiently and at low cost.

As mentioned above, although embodiment of this invention was described in detail, unless it deviates from the technical idea of this invention, it is not limited to these, A some design change etc. are possible.
For example, the shapes of the molds 21 and 21 are not limited to a rectangular shape in plan view, and various shapes can be employed. For example, the groove portion 13 and the rising portion 14 may be formed by using molds 21 and 21 having a planar view shape substantially the same as the planar view shape of the channel 4, that is, a curved planar view shape. In this case, since the groove portion 13 and the rising portion 14 can be made closer to the shape of the flow path 4 and the blade 3, the subsequent finishing process can be performed more easily.

  Moreover, in order to be able to form the flow paths 4 and the blades 3 of various shapes by cutting in the finishing process, the groove portions 13 and the rising portions 14 that can be formed in the flow paths 4 and the blades 3 of the various shapes are provided. You may employ | adopt the metal mold | dies 21 and 21 of the shape to form. That is, rather than using the molds 21 and 21 that can mold the groove 13 and the rising portion 14 corresponding to the impeller 1 having a certain shape, the groove 13 and the rising portion 14 that are versatile for various impellers 1 are used. Molds 21 and 21 that can be molded may be used. In this case, the shape of the molds 21 and 21 in a plan view can be a simple shape such as a substantially rectangular shape or a substantially square shape.

  Further, in the present embodiment, forging is performed with a pair of molds 21 and 21, but forging may be performed with a single mold 21 and 21, and forging with three or more molds 21 and 21. You may go.

  In the embodiment, the manufacturing method has been described by taking an open impeller as an example. However, the present invention may be applied to a manufacturing method of a closed impeller provided with a shroud that covers the entire plurality of blades 3. In this case, the operator welds and fixes the shroud onto the blade 3 after the finishing process.

DESCRIPTION OF SYMBOLS 1 Impeller 2 Hub 3 Blade 4 Flow path 10 Disc-shaped member 11 Impeller material 12 Inclined curved surface 13 Groove portion 14 Raising portion 20 Table unit 21 Mold 22 Roll mill 23 Ring-shaped member

Claims (3)

A method of manufacturing an impeller in which a plurality of blades extending in a radial direction are provided at intervals in a circumferential direction on a hub having a disk shape, and a flow path is formed between adjacent blades,
From a disk-shaped member made of carbon steel, a base material forming step of forming a base material having an inclined curved surface that gradually decreases in diameter toward one end side;
For the outer peripheral side region that is a predetermined range from the outer peripheral side of the inclined curved surface toward the radially inner side, forging using a mold having a shape corresponding to the flow path is sequentially performed in the circumferential direction, A forging step of forming a groove in a portion to be a flow path and forming a rising portion in a portion to be the blade;
A finishing step for forming the hub, the blade, and the flow path by cutting the inner peripheral side region radially inward of the groove portion, the rising portion, and the outer peripheral side region of the base material. An impeller manufacturing method characterized by the above.   2. The impeller manufacturing method according to claim 1, wherein the forging step is performed by a plurality of molds arranged at intervals corresponding to a pitch of the flow path in a circumferential direction.   The impeller manufacturing method according to claim 1, wherein the forging step is performed in a state where an outer periphery of the base material is constrained by a ring-shaped member.

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