JP2002346671A - Butterfly valve and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a butterfly valve having high productivity and excellent shape accuracy by reducing the number of molding man-hours of the inner tube of the butterfly valve. SOLUTION: A peripheral wall of a round tubular material tube is bent and formed, and a hydraulic forming tube 4 in which a plurality of wavy projections 40, 40... are provided in the longitudinal direction at every pitch is manufactured. This hydraulic forming tube 4 is cut in the shaft cross section at neat the apex of each the wavy projection 40, 40..., the half parts of the wavy projections 40, 40... are remained on both sides of a short tubular body, and these comprise an inner tube 1 as gasket seats 10, 10... whose diameters are expanded in a circular plate shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a butterfly valve (butterfly valve) having a structure in which a flow passage inside a valve box is opened and closed by a valve plate that swings around a valve axis substantially orthogonal to the flow passage, and its manufacture. More specifically, the inner cylinder provided with a disk-shaped gasket seat at both ends of the cylindrical portion forming the flow path is fitted in a cylindrical outer cylinder as an outer shell formed separately from the inner cylinder. The present invention relates to a butterfly valve which is fixed to constitute the valve box and a method for manufacturing the butterfly valve.

[0002]

2. Description of the Related Art A butterfly valve (butterfly valve) in which a flow passage formed inside a valve box is opened and closed by a valve plate that swings around a valve axis substantially orthogonal to the flow passage, It has a structural advantage that the configuration is simple, and has an operational advantage that the opening and closing operation from fully closed to fully opened can be performed by swinging the valve shaft and the valve plate by approximately 90 °. It is widely used mainly as a valve for opening and closing a flow path in a piping system for low-pressure fluid.

[0003] The valve plate of such a butterfly valve is a disk having flat portions at two locations radially opposed to each other on the circumferential surface thereof, and a valve protruding from each of the flat portions in the radial direction. It is supported in the valve box via a shaft. Therefore, the flow path inside the valve box in which such a valve plate is disposed increases the close contact with the seal ring held on the peripheral surface of the valve plate when the valve plate is closed, in order to obtain a reliable closed state. The cross section has a cross-sectional shape corresponding to the valve plate, that is, a circular cross-section having two flat portions for valve shaft insertion at radially opposed positions.

[0004] Japanese Patent Publication No. 3-50150 and Japanese Patent Publication No. 3-75791 by one of the applicants of the present invention disclose the formation of a flow path in order to realize the above-mentioned flow path inside the valve box with high accuracy. A butterfly valve is disclosed in which an inner cylinder is manufactured by press-molding a tube material, and the inner cylinder is internally fitted and fixed to an outer cylinder having a simple cylindrical shape to constitute a valve box.

FIG. 8 is an external perspective view of an inner cylinder of this type of butterfly valve. As shown in the figure, the inner cylinder 1 has a gasket seat 10 having a flat bottom and a disc shape with both ends of a cylindrical portion forming a flow path being enlarged in diameter.
The gasket seats 10 and 10 are used to form the valve box by being fitted inside a cylindrical outer cylinder through these gasket seats 10 and fixed to each other by joining means such as welding. .

The valve plate 3 for opening and closing the inner flow passage of the inner cylinder 1 has a disk shape as schematically shown by a two-dot chain line in FIG. In some places, a flattened seat for projecting the valve shaft 30 as a swing shaft
In order to correspond to these seat portions 31, 31, the cylindrical portion of the inner cylinder 1 has two flat portions 11, which have an appropriate width and are radially opposed to each other. An insertion hole 12, 12 for the valve shaft 30 is formed in the center of the flat portion 11, 11.

FIG. 9 is an explanatory view of a conventional manufacturing procedure of the inner cylinder 1 as described above. In manufacturing the inner cylinder 1, FIG.
As shown in FIG. 9A, a circular tube cut in advance to a predetermined length is used as a raw tube A. First, as shown in FIG. 9B, both ends of the raw tube A are tapered. First molded tube A ₁
Create and then subjected to molding to increase the inclination angle of the expansion ratio and the taper portions at both ends enlarged diameter portion of the first forming tube A ₁ stepwise, FIG 9 (c) and FIG. 9 (d) As shown in the second,
The third formed pipes A ₂ and A ₃ are prepared.

The third molded tube A ₃ shown in FIG. 9 (d) has the enlarged diameter portions at both ends provided with the required enlarged diameter ratio and shape as the gasket seats 10, 10. And the cross-sectional shape of the circular tube used as the base tube A. Then
The third necessary or locations of the tubular portion circumferential surface of the forming tube A ₃ is flattened,
As shown in FIG. 9 (e), said creating a fourth forming tube A ₄ comprises a flat portion 11, 11 (only one side is shown), and finally, the insertion hole 12 in the center of the flat portion 11, 11, Open 12 and
The inner cylinder 1 as shown in FIG. 9F and FIG. 8 is manufactured.

[0009] Figure 10 is an illustration of a second method of molding from the molding pipe A ₂ into the third forming tube A ₃ in the above manufacturing procedures. The third molded tube A ₃ is obtained by press-molding the second molded tube A ₂ between the upper mold B and the lower mold C. Upper die B and the lower mold C, the maximum inner mold B _1, the C _1, the enlarged diameter end of the third forming tube A ₃ having an outer shape corresponding to the inner dimensions shape of the third half of the forming tube A ₃ They are integrally formed inside cylindrical outer dies B ₂ and C ₂ having an inner diameter corresponding to the outer diameter.

A second forming tube A ₂ as the material, FIG. 10 (a)
As shown in (1), it is set coaxially on the lower die C, and is clamped between the lower die C and the upper die B approaching and moving toward the lower die C. After this,
When the upper mold B is further moved closer, each inner mold B _1,
Each half of the upper and lower second forming tube A ₂ is made to the enlarged diameter so as to conform to the shape of C _1, as shown in FIG. 10 (b), when the upper die B and the lower die C has joined together, these Half of each side is formed by the inner dies B ₁ and C ₁ to obtain a third formed tube A ₃ . The molding of the raw tube A into the first molded tube A ₁ and the molding of the first molded tube A ₁ into the second molded tube A ₂ are similarly performed using the corresponding upper and lower dies. Done.

[0011]

In the manufacturing method of the inner cylinder 1 performed as described above [0008], separate the molding process from blank tube A to the third forming tube A ₃ a plurality of times, the outer diameter of the blank tube A This is because the diameter expansion ratio from the gasket to the outer diameter of the gasket seats 10 is large. Since the outer diameter of the gasket seats 10 and 10 is selected according to the required area of the gasket to be mounted on this,
In some cases, the diameter expansion ratio is further increased, and four or more molding steps are required.

The upper mold B and the lower mold C used for molding the third molded pipe A _{3 have} a contact surface with the second molded pipe A ₂ in order to enable deformation when the two are approached. must have a tapered surface, the third forming tube a ₃ on both sides of the gasket seat 10, 10 is formed along the tapered surface, shallow outer peripheral side, and the inner peripheral side with deep tapered bottom desirable Flat-bottomed disk-shaped gasket seat 10,
In order to form 10, another one-step molding is required for shape correction.

As described above, in the manufacture of the conventional inner cylinder 1 of a butterfly valve, a large number of molding steps are required for forming the gasket seats 10, and thereafter, the flat parts 11, 11 are formed. ,
In addition, a large number of man-hours are required including drilling of the insertion holes 12 and 12, and there is a problem that it is difficult to ensure accuracy in each molding process.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and reduces the number of molding steps for the inner cylinder of a butterfly valve, and provides an inner cylinder that can be manufactured with high productivity and good shape accuracy. It is another object of the present invention to provide a butterfly valve provided with the same and a method of manufacturing the butterfly valve.

[0015]

A butterfly valve according to a first aspect of the present invention has a cylindrical body having flat portions for inserting a valve shaft at two locations radially opposed to each other. A butterfly valve having a valve box formed by internally fitting and fixing an inner cylinder having a gasket seat whose diameter is increased in a dish shape to an outer cylinder via the gasket seat. A molded tube formed by bending into a waveform at predetermined intervals in the longitudinal direction is cut at an axial section near the apex of each waveform, and half of the waveform remaining on both sides of each cut piece is configured as the gasket seat. It is characterized by the following.

In the present invention, a molded pipe having a peripheral wall in which a plurality of corrugated projections are juxtaposed at appropriate pitches in the axial direction is used as a material, and this molded pipe is used as a shaft near the apex of each waveform. The inner half of the butterfly valve is cut in cross section and the half of the waveform remaining on both sides of each cut piece is used as a gasket seat.

A butterfly valve according to a second aspect of the present invention is characterized in that a hydraulic formed tube formed by the action of hydraulic pressure applied to the inside thereof is used as the formed tube.

In the present invention, the peripheral wall of the tubular material tube is bent and formed by the action of the hydraulic pressure introduced into the inside of the tube to form a plurality of corrugated projections arranged at appropriate pitches in the axial direction. This hydraulic tube is cut at the axial section near the top of each waveform, and the half of the waveform remaining on both sides of each cut piece is used as a gasket seat to form the inner cylinder of the butterfly valve. I do. This type of hydroformed pipe has been commercialized as a flexible tube that is used in the middle of the piping system to absorb the vibration of the piping system for fluid transport.

Further, according to a third aspect of the present invention, there is provided a method for manufacturing a butterfly valve, comprising a cylindrical shape having flat portions for inserting a valve shaft at two locations opposed in a radial direction, and both end portions in the axial length direction. In a method of manufacturing a butterfly valve having an inner cylinder which is internally fitted and fixed to an outer cylinder via a gasket seat formed by expanding the diameter of a circular plate into a disc shape, a material pipe inserted through a mandrel is provided. The mandrel is sandwiched between a pair of dies which are separated from and in the axial direction on the outside of the mandrel, and these dies are moved along the mandrel while applying hydraulic pressure to the inside of the material pipe. Hydraulic forming in which the peripheral wall of the material pipe which bulges outward by the action of the hydraulic pressure is bent into a waveform along the mating shape of the two dies, thereby forming a waveform at predetermined intervals in the axial direction. A hydraulic molded tube having a peripheral wall having a bent portion is manufactured, and the hydraulic molded tube is Of cut in the axial cross-section near the apex of the waveform, characterized in that it constitutes the inner cylinder half portion of the waveform that remains on both sides of each cut piece as the gasket seat.

In the present invention, a hydraulic mandrel for manufacturing a flexible tube, which includes a cylindrical mandrel and a pair of molds which are separated from and separated in the axial direction outside the mandrel, is inserted through the mandrel. A peripheral wall having a plurality of corrugated portions at predetermined intervals in the axial direction by repeating a molding procedure in which the molds holding the outside of the material pipes are moved close to each other while applying hydraulic pressure to the inside of the material pipe. After manufacturing the hydraulic formed tube comprising, by the procedure of cutting this hydraulic formed tube near the apex of each waveform bent portion, the number of butterfly valve inner cylinders corresponding to the number of the formed waveform bent portion, Each of them is manufactured with high productivity and good shape accuracy by one molding.

Further, a method for manufacturing a butterfly valve inner cylinder according to a fourth invention of the present invention is the method for manufacturing a butterfly valve according to the third invention, wherein the mandrel and the clamping portion of the material tube of the pair of molds are provided. The two parts radially opposed to each other have a flattened circular cross section, and the flat part for inserting the valve shaft is formed at once by the approaching operation of the mold in the process of the hydraulic forming. I do.

In the present invention, when the peripheral wall of the material pipe is bent into a corrugated shape by setting the shapes of the mandrel and the mold, the tubular portion between each corrugated portion is formed in the axial section required for the butterfly valve inner cylinder. That is, the two portions radially opposed to each other are formed into a circular cross-section having a flattened shape, and the post-forming of the cylindrical portion between the gasket seats obtained by cutting at the top of the corrugation becomes unnecessary, thereby further reducing man-hours.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a longitudinal sectional view of a butterfly valve according to the present invention. This butterfly valve is the same as
As in the butterfly valve disclosed in Japanese Patent Publication No. 50, Japanese Patent Publication No. Hei 3-75791, etc., a valve in which an inner cylinder 1 forming a flow path is internally fitted and fixed to an outer cylinder 2 having a simple cylindrical shape. A valve plate 3 is provided inside the box.

The inner cylinder 1 is formed by forming gasket seats 10 and 10 having a flat bottom and a disc shape by expanding the diameters of both ends of a cylindrical portion forming a flow path, and through these gasket seats 10 and 10. And is fixed inside by a joining means such as welding. The valve plate 3 is a disk having an integrally provided radially penetrating valve shaft 30, a rubber seal ring 31 wound around the outer periphery thereof, and fitted into the cylindrical portion of the inner cylinder 1.

The valve shaft 30 protrudes outside the inner cylinder 1 through insertion holes 12 and 12 (see FIG. 8) formed at corresponding positions of the inner cylinder 1, and has a short protrusion on one side. The portion is supported by a support bush 13 disposed inside the outer cylinder 2 so as to face an outer position of the corresponding insertion hole 12. The long protrusion on the other side extends radially through the peripheral wall of the outer cylinder 2 and extends into the support cylinder 20 facing the outer position of the insertion hole 12 on the same side. It is supported by a support bush 14 fitted to the.

At the end of the support cylinder 20 extending outward from the outer cylinder 2, a fixed flange serving as a mounting seat for opening / closing operation means (not shown) such as an opening / closing lever, an opening / closing handle, and an opening / closing motor is provided.
23 are provided. The tip of the valve shaft 30 has an annular collar.
It is sealed by an O-ring 25 that has been prevented from coming off by 24, protrudes substantially at the center of the fixed flange 23, and is connected to the operating means attached to the fixed flange 23.

In the butterfly valve configured as described above, annular gaskets G, G are attached to gasket seats 10, 10 on both sides of the inner cylinder 1, and between the pipe flanges F, F indicated by two-dot chain lines in FIG. By inserting these pipe flanges F, F in the circumferential direction with a plurality of through bolts 15, 15,... And pressing against the gaskets G, G, the valve box including the inner cylinder 1 and the outer cylinder 2 is closed. It is used by being installed in the middle of the piping system in a liquid-tight manner.

In this state, the inner cylinder 1 forms a flow path which is continuous with the piping system, and this flow path is opened and closed by the valve body 3 which swings together with the valve shaft 30 in accordance with the operation of the operating means. FIG.
Shows the state of the valve body 3 when fully closed, at this time, the valve body 3 is orthogonal to the axis of the inner cylinder 1, and the flow path is formed through the outer peripheral seal ring 31. It is closed by the valve body 3 which is in close contact with the first cylindrical portion. The valve element 3 in such a state
Swings 90 ° together with the valve shaft 30 to become parallel to the axis of the inner cylinder 1, and the flow path is fully opened except for the thickness of the valve body 3.

As shown in FIG. 8, the inner cylinder 1 of the butterfly valve as described above has flat portions of appropriate width at two radially opposed portions of the cylindrical portion sandwiched between the gasket seats 10 on both sides. Parts 11, 11, and the center of these flat parts 11, 11,
It is configured by opening insertion holes 12 and 12 through which 30 is inserted. The feature of the present invention resides in the configuration of the inner cylinder 1 as described above, and further in the method of manufacturing the inner cylinder 1. FIG. 2 is an explanatory diagram of a manufacturing procedure of the inner cylinder 1 of the butterfly valve according to the present invention.

In manufacturing the inner cylinder 1 of the butterfly valve, FIG.
A hydraulic forming tube 4 as shown in FIG. The hydraulic forming tube 4 is formed by bending the peripheral wall of a cylindrical material tube and arranging a plurality of tubes (3 in the figure) at appropriate intervals in the axial direction.
) Are formed in the middle of the piping system for fluid transport, and various vibrations such as vibrations caused by the action of internal flow and vibrations caused by external vibrations are formed. Are used as a flexible tube that absorbs by the elastic deformation of each of the corrugated projections 40, 40. Note that the number of the corrugated projections 40, 40...
The number is not limited to three as shown in (a), and can be appropriately set within a range not exceeding the size and the length of the material tube to be described later.

The corrugated projections 40 of the hydraulic forming tube 4 used in the present invention have a shaft length approximately twice the depth of the gasket seats 10 at both ends of the inner cylinder 1 to be obtained as a product. Is formed. The length of the cylindrical portion between the adjacent wavy projections 40, 40 corresponds to the cylindrical portion between the gasket seats 10, 10 on both sides of the inner cylinder 1. As shown by a two-dot chain line in FIG. 2A, the flat forming portions 41, 41 corresponding to the flat portions 11,
(Only one side is shown) can be integrally formed.

The hydroformed pipe 4 constructed as described above is cut along an axial section near the apex of each of the corrugated projections 40, that is, along a cutting line shown by a broken line in FIG. Is done. As described above, each corrugated projection 40 has an axial length approximately twice the depth of the gasket seat 10 to be obtained, and a cut piece cut along the cutting line is shown in FIG. As described above, half of the corrugated projections 40 are left on both sides of the short cylindrical body, and these half portions constitute the gasket seats 10 as a disk-shaped enlarged portion.

Therefore, when the flat molded portions 41, 41 are integrally molded, an insertion hole for inserting the valve shaft 30 is provided at the center of the flat molded portions 41, 41.
When the flat portions 11 and 11 are formed by opening 12 and 12, and when the flat forming portions 41 and 41 are not integrally formed, the cylindrical portions of the individual cut pieces are flattened at positions facing the radial direction. After that,
Open the insertion holes 12 and 12 at the center of the flattened part
By configuring 11, 11, the inner cylinder 1 having a shape as shown in FIG. 8 can be manufactured. In the manufacture of such an inner cylinder 1, a molded tube molded by a molding method other than hydraulic molding may be used as long as it has the same shape as the hydraulic molded tube 4.

FIG. 3 shows a raw material tube used for manufacturing the above-described hydroformed tube 4. Material tube 5 as shown
Is a tubular body having a circular cross-section, the tip of which expands in a tapered shape at a small diameter expansion ratio over an appropriate length,
Flat portions 51, 51 (only one side is shown) having a predetermined width are provided at two locations on the circumference of the enlarged diameter portion 50 facing each other in the radial direction, so that the cross-sectional shape of the cylindrical portion of the inner cylinder 1 as a final product is obtained. The corresponding preforming is performed.

This preforming is performed only at the distal end of the material tube 5 so that it can be mounted on a forming apparatus for hydraulic forming. For example, in FIG. As shown in the figure, a punch P having a predetermined cross section having a tapered tip portion having a reduced diameter can be easily implemented by driving the punch P into the tip of a tubular material having a circular cross section. In the case of post-forming the flat forming portions 41, 41, the pre-forming only needs to expand the diameter of the distal end portion of the circular tube to a predetermined inner diameter.

FIG. 4 and FIG. 5 are explanatory diagrams of the forming procedure of the hydraulic forming tube 4. For this molding, a molding apparatus obtained by slightly improving the apparatus practically used for manufacturing the above-described flexible tube is used. This device includes a mandrel 6 and a pair of dies (fixed die 7 and movable die 8) arranged outside the mandrel 6 in the axial direction.

As shown in FIG. 3, the mandrel 6 has a cross section corresponding to the tip of the preformed material tube 5, that is, a flat section having a predetermined width is provided at two locations radially opposed to each other in a circular cross section. And has a fixed cross-sectional shape and is immovable in the axial direction. At the tip of the mandrel 6, the other part of the material tube 5, that is, a cylindrical part 60 having a circular cross section corresponding to a circular pipe part that is not preformed is coaxially connected. And a seal ring 61 such as an O-ring,
Sealing portions are formed to seal the inner surface of the material tube 5 which is wound around and which is fitted to the outside as will be described later in a liquid-tight manner. Between these sealing portions, an axial center portion of the mandrel 6 is provided. And a high-pressure liquid (generally high-pressure water) is guided through a pressure guiding hole 63 communicating with the outer periphery near the base end of the cylindrical portion 60.

FIG. 6 is an external perspective view of the fixed mold 7.
As shown in the figure, the fixed mold 7 is provided with a support hole 71 corresponding to the cross-sectional shape of the mandrel 6 at an axial center thereof, and the center of a flat portion provided at two places of the support hole 71 can be divided into two. On one surface (the front surface in FIG. 6) of the periphery of the support hole 71, a molding recess corresponding to a half portion of the wavy projection 40 is provided.
70 are formed. The flat portion on the periphery of the support hole 71 can be formed with high precision by a configuration in which a rectangular block 72 is fitted into a concave groove provided in a continuous portion of the support hole 71 to the split surface.

FIG. 7 is an external perspective view of the movable mold 8.
As shown in the drawing, the movable die 8 has a support hole 81 at the axial center thereof similarly to the fixed die 7,
One side (front in Fig. 7)
A shaping recess 80 corresponding to a half of the corrugated projection 40 is formed so as to surround the outside of the support hole 81.

The support hole 81 of the movable mold 8 is, like the support hole 71 of the fixed mold 7, a flat portion formed by fitting rectangular blocks 82, 82 at two places on the periphery including the split surface. The support hole 81 has a cross-sectional shape corresponding to the mandrel 6 and is formed over a predetermined depth from the one surface. On the inner side of the support hole 81, the cylindrical portion 60 at the tip of the mandrel 6 is provided. Corresponding small-diameter holes 83 having a circular cross section are coaxially connected via tapered reduced-diameter portions. The moving mold 8 shown in FIG.
The shaft length has been reduced from the actual size.

The stationary mold 7 constructed as described above is disposed outside the distal end of the mandrel 6 and shown in FIGS.
The fixed frame 9 which is partially shown inside supports the recess 70 from the opposite side to the surface on which the recess 70 is formed so that it cannot move in the axial direction. In addition, the movable mold 8 configured as described above is provided with the concave portion outside the cylindrical portion 60 connected to the tip of the mandrel 6.
The forming surface of 80 is arranged so as to face the fixed mold 7,
It is configured to be pressed by a press head 90 contacting the other surface and move toward the fixed mold 7 along a guide rod 91 provided between the fixed frame 9 and the fixed frame 9.

The material tube 5 configured as described above is
As shown in FIG. 4 (a), the mandrel 6 is externally fitted to the cylindrical portion 60, and the preformed portion at the distal end is fitted to the mandrel 6 and set. Thereafter, the fixed mold 7 and the movable mold 8 each of which is in a split state are combined, and FIG.
As shown in (b), the outside of the fitting portion to the mandrel 6 is gripped by the support hole 71 on the inner periphery of the fixed mold 7, and the outside of the fitting portion to the cylindrical portion 60 is fixed to the fixed mold 7. The molding preparation is completed by being gripped by the small-diameter hole 83 on the inner periphery of the movable mold 8 that is separated from the mold.

At this time, inside the material tube 5, a seal ring 61 on the outer periphery of the cylindrical portion 60 and a seal ring 62 on the outer periphery on the tip side of the mandrel 6 are provided with the movable mold 8 and the fixed mold 7.
And a pressure chamber sealed on both sides in a liquid-tight manner is formed. The material tube 5 set in this way is connected to the pressure chamber sealed on both sides. It is formed by introducing high-pressure water through the hole 63 and pressing and moving the movable mold 8 by the press head 90. FIG. 5A shows an initial state of molding, and FIG.
(B) shows a state after completion of molding.

As shown in FIG. 5A, the material tube 5 is
Due to the pressure of the high-pressure water introduced into the pressure chamber, the movable mold 8 is deformed so as to bulge outward between the contact portions of the fixed mold 7 and the movable mold 8. , And butted against the fixed mold 7 as shown in FIG. As a result, the material tube 5 is deformed along the inner surfaces of the recesses 70 and 80 formed at the mating portion of the two dies 7 and 8, and the corrugated projections 40 corresponding to these recesses 70 and 80 are formed. At the same time, one side portion of the wave piece projection 40 is deformed along the inner surface of the support hole 81 of the movable mold 8, and the preform 42 having the outer shape corresponding to the mandrel 6 is integrally formed. .

After the completion of the molding, the fixed mold 7 and the movable mold 8 are opened, and the material tube 5 is moved toward the mandrel 6.
Pre-formed part obtained by the previous molding
4 is fitted to the mandrel 6 and the procedure shown in FIGS. 4 and 5 is repeated to manufacture the hydraulic forming tube 4 shown in FIG.

The hydroformed tube 4 manufactured in this manner requires only one shaping for each of the corrugated projections 40, 40... Arranged in the axial direction, and is obtained by each shaping. The corrugated projections 40, 40... Correspond to the shapes of the recesses 70, 80 of the mating portion of the fixed mold 7 and the movable mold 8 with high accuracy, and high shape accuracy is obtained. The shaping portion 42 is a wavy projection 4 having the flat shaping portions 41, 41.
It becomes a cylindrical part between 0, 40 ... Therefore, the manufacture of the inner cylinder 1 using such a hydraulic forming tube 4 is performed by the gasket seats 1 on both sides.
Batch molding of the flat portions 11 and 11 at 0 and 10 and two locations facing in the radial direction, cutting at the apex of each corrugated projection 40,
Only three steps of drilling the insertion holes 12 and 12 with respect to 11 are required, and compared with the conventional manufacturing method shown in FIG.
Significant man-hour reduction is possible.

[0047]

As described above in detail, in the butterfly valve according to the first invention of the present invention, the peripheral wall is formed into a waveform by bending at predetermined intervals in the axial direction. Cut at the axial cross section near the vertex, and the inner cylinder is configured as a gasket seat with half of the waveform remaining on both sides of each cut piece, so the man-hours required for manufacturing the inner cylinder is greatly reduced, and high productivity is achieved. And a butterfly valve that can be manufactured.

In the butterfly valve according to the second aspect of the present invention, the peripheral wall of the circular material tube is bent and formed by the action of hydraulic pressure introduced into the inside of the circular tube as a molded tube used for manufacturing the inner cylinder. The use of a hydraulically formed tube formed with a plurality of corrugated protrusions arranged at appropriate pitches in the axial direction enables the production of an inner cylinder with high shape accuracy with high productivity and good shape accuracy. Can be provided at low cost.

In the method of manufacturing a butterfly valve according to the third aspect of the present invention, while applying a hydraulic pressure to the inside of the material pipes inserted through the mandrel, the molds for clamping the outsides thereof are moved close to each other. By repeating the forming procedure of abutting each other, a hydraulic formed pipe having a peripheral wall having a plurality of corrugated portions at predetermined intervals in the axial direction is manufactured. By the procedure of cutting
The number of inner cylinders corresponding to the number of corrugated bends can be manufactured with good shape accuracy by one molding for each.

Further, in the method for manufacturing a butterfly valve according to the fourth invention of the present invention, the holding section between the mandrel and the pair of mold material pipes has a circular cross section in which two radially opposed portions are flattened. As a result, in the process of hydraulic forming, the flat portion for inserting the valve shaft can be formed at a time, so that post-forming of the flat portion after cutting at the top of the waveform is not required, thereby further reducing man-hours. The present invention has excellent effects.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a butterfly valve according to the present invention.

FIG. 2 is an explanatory view of a manufacturing procedure of an inner cylinder of a butterfly valve according to the present invention.

FIG. 3 is a view showing a material tube used for manufacturing a hydroformed tube.

FIG. 4 is an explanatory view of a forming procedure of a hydraulic forming tube.

FIG. 5 is an explanatory diagram of a forming procedure of a hydraulic forming tube.

FIG. 6 is an external perspective view of a fixed mold used for molding a hydraulic molding tube.

FIG. 7 is an external perspective view of a movable mold used for molding a hydraulic molding tube.

FIG. 8 is an external perspective view of an inner cylinder of the butterfly valve.

FIG. 9 is an explanatory view of a conventional manufacturing procedure of an inner cylinder of a butterfly valve.

10 is an explanatory diagram of a method of forming a formed tube in the manufacturing procedure shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner cylinder 2 Outer cylinder 3 Valve plate 4 Hydraulic forming tube 5 Material tube 6 Mandrel 7 Fixed mold 8 Moving mold 10 Gasket seat 11 Flat part 12 Insertion hole 40 Corrugated projection 41 Flat molded part

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Takami Tanaka, Inventor 1-112 Kitahorie, Nishi-ku, Osaka City, Osaka Prefecture Inside Kurimoto Ironworks Co., Ltd. (72) Hideo Kawamura 1-1-12 Kitahorie, Nishi-ku, Osaka City, Osaka Prefecture No. 19 Inside Kurimoto Ironworks Co., Ltd. 8-8-8 F-term (reference) in Yamamoto Hydraulic Works, Ltd. 3H051 AA02 BB01 CC11 DD02 EE02 3H052 AA02 BA26 CC14

Claims (4)

[Claims] An inner cylinder having a gasket seat whose diameter is increased in a disk shape at both ends in the axial length direction of a cylindrical body having flat portions for inserting a valve shaft at two locations radially opposed to each other. In a butterfly valve configured to form a valve box by internally fitting and fixing to an outer cylinder via a seat, the inner cylinder is formed by bending a peripheral wall thereof into a waveform at predetermined intervals in an axial direction. A butterfly valve, wherein a cut is made at an axial cross section near the apex of each waveform, and half of the waveform remaining on both sides of each cut piece is configured as the gasket seat. 2. The butterfly valve according to claim 1, wherein a hydraulic formed tube formed by the action of hydraulic pressure applied to the inside thereof is used as said formed tube. 3. A gasket seat having a cylindrical shape having flat portions for inserting a valve shaft at two locations opposed in a radial direction, and having both ends in the axial direction expanded in a disk shape. In a method for manufacturing a butterfly valve provided with an inner cylinder that is internally fitted and fixed to an outer cylinder to form a valve box, a material pipe inserted through a mandrel is connected to the mandrel in an axial direction outside the mandrel. It is sandwiched between a pair of molds to be separated, and these molds are brought close together along the mandrel while applying hydraulic pressure to the inside of the material pipe, and bulged outward by the action of the hydraulic pressure. By hydraulic forming in which the peripheral wall of the material pipe is bent into a waveform along the shape of the two molds, a hydraulic molded pipe having a peripheral wall having a waveform bent portion at predetermined intervals in the axial direction is manufactured. This hydroformed tube is cut at the axial section near the top of each waveform, and Method for manufacturing a butterfly valve, characterized in that constituting the inner cylinder half portion of the waveform that remains on both sides of fragment as the gasket seat. 4. A clamping section between said mandrel and said pair of molds for said material tube has a circular cross section in which two radially opposed portions are flattened, and said mold in the process of hydraulic forming is formed. 4. The method for manufacturing a butterfly valve according to claim 3, wherein the flat portion for inserting the valve shaft is formed at once by an approach operation.