JPH07103878B2 - Pump casing and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pump casing for manufacturing a steel sheet by press forming or the like, and more particularly to a pump casing for a centrifugal pump.

[Conventional technology]

Conventionally, when a steel plate is press-molded to manufacture a casing, it has been constituted by a cylindrical outer casing and a guide vane or a volute member that forms a flow path inserted inside as a separate body.

FIG. 7 (a) is a vertical sectional view showing the above conventional example, and FIG. 7 (b) is an AA vertical sectional view of the same. This is a volute caulking made by pressing a metal plate without using a cast product.
The volute casing that forms the volute chamber 4 that guides the liquid to be ejected to the ejection port 11 has side plates 5 and 6 on both sides,
A peripheral side plate 7 provided on the peripheral edge of each of the side plates 5 and 6, and a volute vane 8 provided in a space formed by the side plate and the peripheral side plate and extending to a predetermined position in the circumferential direction. The side plates 5, 6, the peripheral side plates 7, and the volute vanes 8 are all formed by molding a metal plate, and the volute casing is radially arranged from the winding start 8a of the volute to a predetermined position 8b. By biasing it, the flow passage cross section of the volute chamber increases as it goes to the discharge port side, and up to the discharge port 11 thereafter, the volute casing is biased in the axial direction so that the flow passage cross section of the volute chamber goes to the discharge port side. It is configured to increase with increasing.

And in the above-mentioned conventional example, since the volute casing, that is, the side plates 5 and 6, the peripheral side plate 7, the volute vanes 8 and the outer plate 9 are all manufactured by press-molding a metal plate, compared with the case of conventional casting. Manufacture is easy and inexpensive, and by biasing the volute channel in the radial direction and the axial direction, the overall radial dimension can be reduced, and the cost can be reduced.

[Problems to be Solved by the Invention]

In the above-mentioned conventional example, since the volute vane 8 is provided inside the pump casing from the winding start portion 8a to the winding end portion 8b, the outer diameter of the outer casing becomes large, and accordingly, the pressure-resistant upper plate thickness is increased. There is a problem in that reinforcement is necessary to prevent an increase in the number of side walls and deformation of the side walls, and as described above, an extra flow path member (volute vane 8) is provided outside the impeller. However, if the method of expanding the volute in the axial direction is adopted in order to save the space of the above, there is a problem that the deterioration of the pump performance cannot be avoided.

Further, in any of the above cases, there is no continuity in the shape in the portion where water flows from the inner flow path member to the outside, which causes the generation of noise and the reduction in efficiency.

In another conventional example, German Patent Application Publication No. 2047501 has a different structure of a volute casing by a press,
That is, there is disclosed a pump casing that expands the volute area in the axial direction inside the cylindrical casing. Since this method increases the volute in the axial direction, its effect is far less than that of the method in which it increases in the radial direction, and it is a compromise solution. Especially, in the case of an impeller having a high rotation speed, there is a drawback that the hydraulic loss becomes extremely large.

In another conventional example, German Patent Publication No. 3008672 discloses a structure of a pump casing in which a volute area is enlarged in a radial direction inside a cylindrical casing. In this case, there is a drawback in that the required material is very large and the manufacturing cost is high.

In another conventional example, French Patent No. 1563797 shows a structure in which a volute part is provided on the outer side in the radial direction of the casing, but the volute part is formed by dividing the casing into two parts and is press-formed integrally with a cylindrical casing. Since it is not, a means for joining is required.

The present invention solves the above problems, and a pump casing and a manufacturing method thereof which directly form a flow passage without providing a separate flow passage member inside a press-molded cylindrical outer casing. It is intended to provide a way.

[Means for Solving the Problems]

In order to achieve the above object, the present invention has one opening of a cylindrical container-shaped casing body, which is manufactured by press-molding a steel plate having an opening on one side and a bottom on the other side, and a flange on the outside. To form a casing flange and open the other bottom to serve as a suction port, at a position radially opposite to the impeller of the intermediate cylindrical part, in the radial direction from the unprocessed cylindrical surface and toward the discharge port. The feature is that the volute part that is projected to increase gradually is integrally formed by press working.

The maximum protruding portion of the volute portion integrally formed by press working on the intermediate cylindrical portion of the cylindrical container-shaped casing body described above is connected to the discharge port through a nozzle that is smoothly welded.

It is characterized in that the overhanging portion of the volute portion integrally formed by the press working is formed so that the width dimension is constant over the entire region and the overhanging height gradually increases in the radial direction.

Further, it is characterized in that the cross-sectional shape of the overhanging portion of the volute portion integrally formed by the press working is trapezoidal or arcuate.

The volute part formed integrally with the intermediate cylindrical part so as to project outward has a cylindrical part formed with a flange expanded outward at one opening, and a concave part corresponding to the volute is formed on the inner surface. It is integrally set by so-called bulge molding in which it is set and mounted in an outer mold, internal pressure is applied to the inside of the cylindrical part, and the cylindrical part is pushed up from below by a pressing mold so as to follow the inner surface of the outer mold. However, the manufacturing method is as follows.

That is, a metal plate is press-molded to form a cylindrical container-shaped casing body having an opening portion on one side and a bottom portion on the other side, and the casing body is formed so as to form a casing flange extending outward from the opening portion. The step of press-molding, and the volute part projecting radially outward from the cylindrical surface of the casing body at the axially intermediate part facing the impeller in the radial direction so as to form a flow path around the pump impeller. The step of press-molding the volute part comprises: (a) forming a recess corresponding to the volute part on the inner surface; A step of setting a cylindrical container-shaped casing body inside the outer mold, and (b) a step of applying internal pressure to the cylindrical portion of the cylindrical container-shaped casing body. Characteristically, the outer mold is composed of a separate mold, and in addition to applying internal pressure, the pressing mold is pressed in the axial direction of the cylindrical surface of the cylindrical container-shaped casing body, and the nozzle has the maximum volute part. The nozzle is characterized in that it is connected to an opening provided in the projecting portion, and the nozzle is characterized in that it is connected to the discharge port on the other side.

[Work]

INDUSTRIAL APPLICABILITY The present invention relates to an inner surface of an intermediate cylindrical portion (itself) of a bowl-shaped cylindrical container-shaped casing body having an opening portion on one side and a bottom portion formed on the other side formed by press-forming a steel plate, and Since the volute parts that project radially in the opposite direction are integrally formed by known bulge forming, during pump operation, the pump casing is driven through the casing flange part integrally formed in one opening on the drive side. When the inner impeller is rotated, the fluid sucked from the suction port formed at the bottom of the cylindrical container-like casing is
The pressure is boosted by the impeller, collected by the volute part inside the casing, and guided to the discharge port through the nozzle connected to form a smooth flow path at the maximum part of the volute part overhanging part, and discharged to the outside.

As described above, since the volute part is molded outward from the casing body, the flow path has a smoother shape than the conventional example, and the volute part (overhang) that requires a gradually increasing cross-sectional area of the flow path Since the shape from (part) to the discharge port through the nozzle is close to the ideal shape, there are steps and gaps between the volute part and the pump casing (outer casing) compared to the conventional example in which the volute is installed. Therefore, there is no performance deterioration or noise generation.

On the other hand, since the diameter of the pump casing is smaller than that of the conventional example, it is possible to reduce the wall thickness corresponding to the internal pressure and increase the rigidity.

Further, since the stick-out part of the volute part is formed so that the width dimension is constant over the entire area and the overhanging height thereof is gradually increased in the radial direction, the water discharged from the impeller smoothly enters the volute part. It is able to flow in, which in turn improves hydraulic efficiency.

Further, when the overhanging portion of the volute portion is integrally formed by bulge forming in order to form the cross-sectional shape of the overhanging portion into a trapezoidal shape or an arcuate shape, the arcuate cross-sectional shape is more desirable. When the cross-sectional shape is arcuate in this way, the following advantages occur.

(I) The so-called contact area with the fluid (wetting surface) is small and the flow path resistance is reduced, so the hydraulic efficiency is improved.

(Ii) Since the plate thickness of the overhang portion after the bulge molding can be made uniform, the strength of the casing is increased.

(Iii) Internal pressure during bulge molding (internal pressur
e) can be set low, and moldability is improved. In contrast,
When the cross-sectional shape is trapezoidal, a large internal pressure is required to form the corner.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a vertical cross-sectional view of a centrifugal pump provided with a steel plate pump casing showing an embodiment of the present invention.
The same reference numerals as those shown in FIG. 5A indicate the same or similar parts.

In the drawing, 21 is a casing body, and the casing body 21 is formed by first deep-drawing a steel plate by pressing to form a cylindrical container-like body having a flange (flange) opening on one side and a bottom on the other side. As shown in FIGS. 6 (a) and 6 (b), the cylindrical container-shaped body is divided into two outer molds 102a each having a recess 101 corresponding to a volute part having a gradually increased flow passage cross-sectional area on its inner surface. , 102b are set and installed, and an oil pressure or an elastic body such as rubber is put inside the intermediate cylindrical portion to apply an internal pressure in the direction of arrow a, and is pressed in the direction of arrow b from below via the pressing die 103. It is press-molded (so-called bulge molding) so as to raise it, and in this way, an overhanging portion corresponding to the volute portion is provided at a position radially opposed to the impeller 1 of the intermediate cylindrical portion of the casing body 21. 21a is formed and one of the The side openings,
A casing flange 21b is provided, and at the other suction side (left side in the figure) bottom, a pump suction port 21d axially protruding to the center is opened via a casing front face part 21c. It is molded integrally.

The overhanging portion 21a forming the volute portion of the casing body 21 has a volute chamber A formed therein, and the overhanging portion 21a defining the outer periphery of the volute chamber A is radially outward from the outer peripheral wall of the casing body 21. It is formed by bulging. As shown in FIG. 4, the projecting portion 21a is formed in a trapezoidal shape ((a ₁ ) to (c ₁ ) in the figure) or an arc shape ((a ₂ ) to (c ₂ ) in the figure). The width dimension B is constant over the entire area, and the overhanging height H of the overhanging height H is from H _{1 to} H _{3 in} the radial direction along the circumferential direction (counterclockwise direction in the figure) starting from the midway. Thus, the flow passage cross-sectional area of the volute chamber A is gradually increased in the direction in which the fluid flows. FIGS. 4a (a) and 4 (b) show patterns of changes in respective cross-sectional shapes.

The casing flange 21b of the casing body 21 is fastened to the drive side of a bearing, a motor, or the like via a casing cover 22, and the casing front face portion 21c is slightly bulged outward, and the volute inner wall is inside thereof. 23 is installed so as to face the shroud of the impeller 1.

Further, at the suction port 21d portion of the casing body 21, a suction flange 24 having a concentric suction port 24a at the center is welded 24b.
A reinforcing plate 25 is attached to the casing main body 21 via a column 26 on the back side of the pipe connecting flange surface 24c of the suction flange 24.

The maximum part of the flow passage cross-sectional area of the volute overhang 21a is
As shown in FIG. 3, it is located at the uppermost portion, and the edge portion 211a of the largest portion has a substantially circular shape which is the same shape as the edge 27a shown in FIG. 5 (c) in this figure. The edge 211
In a, a nozzle having an edge 27a shown in FIG.
27 is integrally attached by welding, and the nozzle 27
Are communicated with the discharge port 28 so as to form a smooth flow path. In the figure, 3 is a shaft sealing device, 24d is a bolt hole drilled in the pipe connection flange surface 24c, and 25a is a reinforcing plate attached to the inside of the discharge flange 29. When the pump casing is attached to the drive side through the casing flange 21b and the casing cover 22 and the internal impeller 1 is rotated during pump operation, the suction port 24a of the suction flange 24 and the suction formed at the bottom of the casing main body 21. The liquid sucked through the mouth 21d is pressurized by the impeller 1, collected by the volute portion 21a inside the casing, and connected to the end portion 211a of the maximum portion of the volute overhang portion so as to form a smooth flow path. It is guided to the discharge port 28 through the nozzle 27 and discharged to the outside.

According to this embodiment, since the volute portion 21a is formed so as to stick out from the casing body 21, the flow passage having a smoother shape than that of the conventional example (FIGS. 7 (a) and (b)). Can be Further, since the flow path from the volute part 21a where the flow path cross-sectional area gradually increases to the discharge port 28 via the nozzle 27 can be formed in a shape close to an ideal shape, as compared with the conventional example in which the volute is incorporated, the volute part is formed. There is no step or gap between the pump and the pump casing (outer casing),
Therefore, it is possible to eliminate performance deterioration and noise generation. On the other hand, since the diameter of the pump casing is smaller than that of the conventional example, the wall thickness corresponding to the internal pressure can be reduced, not only the rigidity is increased, but also the size of the bolt inserted into the mounting bolt hole 21e of the casing flange 21b. And the number can be reduced.

FIG. 1a is a longitudinal sectional view showing another embodiment, in which the volute inner wall 23 of FIG. 1 is omitted. Further, FIG. 2 is a longitudinal sectional view showing another embodiment, in which the same reference numerals as those shown in FIG. 1 designate the same parts. In this embodiment, the inner wall 23 of the volute shown in FIG. 1 is omitted, and the casing front surface portion 21c 'is formed in substantially the same shape as the inner wall of the volute. According to this embodiment, the inner wall of the volute is unnecessary as compared with the one shown in FIG. 1, and the production is facilitated.

〔The invention's effect〕

As described above, according to the present invention, one opening of the cylindrical container-shaped casing body is expanded outward to form the casing flange, and the other bottom is opened to form the suction port, and the impeller of the intermediate cylindrical portion is formed. The following effects can be obtained by integrally molding the volute portion that projects outwardly from the cylindrical surface and gradually increases toward the discharge port at a position opposite to.

(I) By forming the volute portion so as to project outward from the casing main body, a flow passage having a smoother shape can be formed as compared with the conventional example in which the volute member is internally provided as a separate body. It can be reduced and the pump performance can be improved.

(Ii) Since the diameter of the pump casing can be made smaller than that of the conventional example, the wall thickness corresponding to the internal pressure can be made thinner and not only the rigidity can be increased, but also the size and number of the mounting bolts for the casing flange can be reduced. .

(Iii) From the volute part that gradually increases the cross-sectional area of the flow path to the discharge port by connecting the maximum overhang part of the volute part integrally formed with the intermediate cylindrical part of the casing body to the discharge port through the nozzle. Since the flow path can be formed into a shape close to an ideal shape, there is no stepped portion or gap between the volute portion and the pump casing as compared with the above-mentioned conventional example, and performance deterioration and noise generation can be eliminated.

In addition, the needle portion of the volute part is formed so that the width dimension is constant and the overhanging height gradually increases in the radial direction over the entire area, so that the water discharged from the impeller smoothly flows into the volute part. It is possible to improve hydraulic efficiency.

Further, by making the cross-sectional shape of the overhanging portion of the volute portion trapezoidal or arcuate, it becomes possible to perform integral molding by bulge molding. In addition, in this case, in particular, the arcuate cross-sectional shape reduces the contact area with the fluid (wetting surface) and reduces the flow path resistance, so not only the hydraulic efficiency is improved, but also the bulge after bulging is increased. Since the plate thickness of the portion can be made uniform, the strength of the casing becomes high, and the internal pressure at the time of bulge forming can be set low, so that formability is improved. The above-described effect is made possible only by integrally forming the overhanging portion of the volute portion with the casing body by the bulge forming method.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a centrifugal pump having a steel plate pump casing showing an embodiment of the present invention, FIGS. 1a and 2 are longitudinal sectional views showing other embodiments, and FIG. 3 is a front view. , FIG. 4 is a cross-sectional view of the same, (a ₁ ) (a ₂ ), (b ₁ ) (b ₂ ),
(C ₁ ) (c ₂ ) and (d) are explanatory views showing two trapezoidal and arcuate sectional shapes of the volute portion at four positions in the circumferential direction, and FIGS. 4a (a) and (b) are volutes. FIGS. 5A to 5D are top views, vertical cross-sectional views, bottom views and side views of the main parts (nozzles), which show changes in trapezoidal and arcuate cross-sectional shapes of the parts. Figure (a) (b)
Is an explanatory view of press working (bulge forming), and FIGS. 7A and 7B are a longitudinal sectional view and an AA sectional view showing a conventional example. 1 ... Impeller, 1a ... Impeller inlet, 2 ... Main shaft, 3 ... Shaft sealing device, 21 ... Casing body, 21a ... Volute part (overhanging part), 21b ... Casing flange, 21c, 21c ′ …… Front part of casing, 21d …… Suction port, 22 …… Casing cover, 23 …… Volute inner wall, 24 …… Suction flange, 24a …… Suction port, 24c, 29 …… Piping connection flange face, 25,25a …… Reinforcement plate, 26 …… Post, 27 …… Nozzle, 28 …… Discharge port, 29 …… Discharge flange, 101 …… Recess, 102a, 102b …… Outer mold, 103 …… Push mold, A …… Volute Chamber, B ... Width of overhang, H ... Overhang height.

Claims (10)

[Claims] 1. A pump casing manufactured by press-forming a steel plate, wherein one opening of a cylindrical container-shaped casing body (21) having an opening on one side and a bottom on the other side is formed in a flange shape outward. To the casing flange (21b), and the bottom of the other side as an opening to form the suction port (21d), at a position radially opposite to the impeller (1) of the intermediate cylindrical portion, and radially outward from the cylindrical surface. Moreover, the volute part (21) protruding so as to gradually increase toward the discharge port (28)
A pump casing characterized in that a) is integrally formed by press working. 2. A nozzle welded to form a smooth flow passage at a maximum protruding portion of a volute portion (21a) integrally formed by press working on an intermediate cylindrical portion of a casing body (21) in the shape of a cylindrical container. The pump casing according to claim 1, wherein the pump casing is communicated with the discharge port (28) through the (27). 3. A protruding portion of a volute portion (21a) integrally formed by press working on an intermediate cylindrical portion of a casing body (21) in the shape of a cylindrical container has a width (B) dimension which is constant over the entire area. The pump cane according to claim 1, wherein the overhang height (H) is formed so as to gradually increase in the radial direction. 4. The cross-sectional shape of the projecting portion of the volute portion (21a) integrally formed by press working on the intermediate cylindrical portion of the casing body (21) in the shape of a cylindrical container is trapezoidal or arcuate. The pump casing according to claim 1. 5. A casing flange (21b), which is formed by press forming a metal plate to form a cylindrical container-shaped casing body (21) having an opening on one side and a bottom on the other side, and which extends outward from the opening. Press-forming the casing body (21) so as to form a pump, and an axial intermediate portion radially opposed to the impeller (1) so as to form a flow path around the pump impeller (1). And a step of press-forming a volute part (21a) projecting radially outward from the cylindrical surface of the casing body (21), and a step of forming an opening as a suction port (21d) in the lower part. A method for producing a steel plate pump casing, comprising: 6. The step of press-molding the volute part (21a) comprises: a) a concave portion (101) on the inner surface corresponding to the volute part (21a).
From the step of setting the cylindrical container-shaped casing body (21) inside the outer mold (102a, 102b) having b, and the step of applying internal pressure to the cylindrical portion of the cylindrical container-shaped casing body (21), The method for producing a steel plate pump casing according to claim 5, wherein 7. The method of manufacturing a steel plate pump casing according to claim 6, wherein the outer mold (102a, 102b) is a separate mold. 8. The steel plate pump casing according to claim 5, wherein the pressing die (103) is pressed in the axial direction of the cylindrical surface of the cylindrical container-shaped casing body (21) while applying internal pressure. A method of manufacturing. 9. The steel plate pump according to claim 5, wherein the nozzle (27) is connected to an opening provided in the maximum overhang portion of the volute portion (21a). A method of manufacturing a casing. 10. The method for manufacturing a steel plate pump casing according to claim 9, wherein the nozzle (27) is connected to the discharge port (28) on the other side.