JPH09239453A - Formation of bellows and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compact a device, to reduce the necessary working force and to obtain a bellows enabling stable seal by expanding/shrinking a core between a die bringing into contact with one side of end part of a base stock pipe and a die bringing into contact with the other side of the end part thereof. SOLUTION: The inner pressure is made to high by supplying hydraulic medium into a hydraulic chamber 10 in the inner part of the base stock pipe 1 by a pump 104 and a pressure controller 108, and the base stock pipe 1 is bulged along split dies 4a, 4b, 4c, 4d surrounding the base stock pipe 1 and the crest parts are formed and the supply of the hydraulic medium is stopped. Successively, spacers 5 are taken off and an upper die 2 is pressed with a slider 60 and pushed down in the axial direction to compression-deform the base stock pipe 1. After completing the formation, the load of the slider 60 in a press machine is removed and the hydraulic medium remained in a hydraulic chamber 10 is escaped and the bollows as a product is taken out by taking off the upper die 2 and the split dies 4a, 4b, 4c, 4d, 4e.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bellows molding method and apparatus thereof, and more particularly to a bellows molding method and a molding apparatus for molding a bellows by applying hydraulic pressure to a straight tube. Used for large bellows for wiring equipment such as gas insulated switchgear.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a bellows by hydraulic forming, a straight tubular base pipe is surrounded by a corrugated split mold having the same axis as the base pipe, and the base pipe is pressurized from inside by a hydraulic medium. The pressure was applied to form the bellows along the corrugated split mold. Alternatively, the straight tubular shell is surrounded by a plurality of split molds having the same axis as the straight pipe, and the split molds are arranged at equal intervals, and as a primary step, the blank pipe is pressurized from inside by a hydraulic medium. The ridges are formed on the blank pipes located between the split dies, and then, as a secondary step, the blank pipes are compressed axially while the hydraulic pressure is applied to the interior of the blank pipes, while the split dies are axially compressed. It was moved to form a bellows. As such a conventional bellows molding method, for example, JP-A-56-1219 and JP-A-59-232.
The thing described in the 627 publication is mentioned.

10 and 11 show a bellows molding apparatus using a conventional core. FIG. 10 is a vertical cross-sectional view showing the structure of a conventional bellows molding apparatus using a core, and FIG.
It is sectional drawing which shows the state which bellows-molded by the apparatus of FIG. In FIG. 10, reference numeral 1 is a straight tubular element pipe for forming a bellows. The core 72 is fixed to the lower mold 3 and fitted in the upper mold 71 with a through hole. The upper mold 71 with a through hole through which the core is inserted and the lower mold 3 are in contact with both open ends of the base pipe 1, and the inside of the base pipe 1 is sealed to form a hydraulic chamber 10.

The upper die 71 with a through hole is provided with a vent hole 7 for venting air existing in the hydraulic chamber 10 when the hydraulic chamber 10 is filled with the hydraulic medium. 7 is connected to the air bleeding valve 102. The lower mold 3 is provided with a hydraulic pressure supply hole 9 for filling the hydraulic pressure chamber 10 with a hydraulic medium, and the hydraulic pressure supply hole 9 is provided with a pressure regulator 108, a stop device, and a stop mechanism via a coupler 107. It is connected to the valve 109 and the relief valve 110.

Split molds 4a, 4b, 4c, 4d and 4e are molds for molding bellows. The spacer 5 is for arranging the split molds 4a, 4b, 4c, 4d, 4e at equal intervals. An O-ring 74 is attached to seal the inside of the base pipe 1 by the upper mold 71 with a through hole and the lower mold 3 that are in contact with the open end of the base pipe 1 to perform sealing. Further, in the portion where the core 72 is fitted with the through-hole upper mold 71, the core 72 is not leaked to the hydraulic medium filled in the hydraulic chamber 10 and the space between the core 72 and the through-hole upper mold 71. An O-ring 73 seals so that it can slide. Reference numeral 60 denotes pressure applied by the slider of the press machine. By applying pressure by the press, the upper die 71 with through holes is pressed.
Is pushed in in the axial direction.

More specifically, first, one end of the core 72 is attached to the lower mold 3. Raw pipe 1
Are attached to the lower mold 3 with the same axis as the core 72, and the split dies 4a, 4b, 4c, 4d, and 4e are set at equal intervals using the spacer 5, and the core 72 is penetrated. It is fitted and attached to the through hole of the upper die 71 with a hole, and the inside of the raw tube 1 is sealed to form the hydraulic chamber 10.

As a primary step, the stop valve 109 is opened to supply the hydraulic medium to the hydraulic chamber 10 inside the raw pipe 1 by low-pressure water supply, and when the hydraulic medium flows out from the ventilation hole 7, the air vent valve 102 And close the stop valve 10 at the same time.
9 is also closed to temporarily stop the supply of the hydraulic medium. After that, the pump 104 and the pressure adjuster 108 continue to supply the hydraulic medium to the hydraulic chamber 10 inside the raw pipe 1 to increase the internal pressure of the hydraulic chamber 10 to partially cut the raw pipe 1 into the split mold 4a. , 4b, 4c, 4
The ridges are formed by bulging along d and 4e to stop the supply of the hydraulic medium.

Next, as shown in FIG. 11, the spacer 5 between the split dies 4a, 4b, 4c, 4d, 4e is removed as a secondary step, and the state in which the hydraulic pressure is applied to the inside of the raw tube 1 is maintained. An upper die 71 with a through hole is formed by the slider 60 of the press.
Is pushed in the axial direction to compressively deform the blank tube 1 which is partially bulged. At this time, the upper die 71 with the through hole is the core 7
2 is used as a guide to slide, and the split mold that surrounds the raw pipe 1 with the same axis as the raw pipe 1 also moves. Here, when the base tube 1 of which a part is bulged by the upper die 71 with a through hole is compressed and deformed, the volume of the hydraulic chamber 10 inside the base tube 1 becomes small and acts on the inside of the base tube 1. Since the applied pressure becomes high, the inside of the hydraulic chamber 10 is adjusted by the relief valve 109 so as to be constant.

After the completion of molding, the slider 60 of the pressing machine pushed in the axial direction is unloaded, and all the hydraulic medium remaining in the hydraulic chamber 10 inside the raw pipe 1 is released.
Upper mold 71 with through holes and split molds 4a, 4b, 4c, 4
Remove d and 4e and take out the bellows which is a molded product.

As described above, there has been a molding method using a core in the related art. However, the role of the core is to guide the core when it is pushed in axially or to prevent the core tube from buckling in the core tube during compression deformation. This is to prevent one of the molds contacting the end of the tube and the core is fixed, and the other mold is provided with a through hole so that the mold can be slid with the core as a guide. ing. Alternatively, each of the molds is provided with a through hole so that the mold can be slid with the core as a guide.

[0011]

In the above-mentioned conventional method, it is remarkable especially when a bellows is formed by using a large-diameter raw pipe, but in the primary step, after forming a mountain portion on the raw pipe, When the base pipe is compressed and deformed in the axial direction with the liquid pressure applied inside the base pipe, the die contacting the end of the base pipe has a large pressure receiving area affected by the liquid pressure. For this reason,
In addition to the force of axially compressing the raw pipe, a force to oppose the hydraulic pressure inside the raw pipe is required, which requires a large processing force for bellows molding. Moreover, when molding a bellows with high peaks, the amount of pushing of the raw pipe increases, so
A long core is required in the axial pushing direction of the raw pipe, and it is necessary to avoid interference with the core during molding in the conventional structure where the core cannot expand and contract, and avoid the core when attaching and detaching the raw pipe and molded products. There is. For this reason, not only the stroke range of the press becomes large, but also the space between the beds of the press becomes large, and an excessively expensive equipment is required.

On the other hand, in the above bellows molding method, in order to mold the bellows, the pressure is applied by the hydraulic medium filled inside the raw pipe, so that the hydraulic medium must be sealed so as not to leak from the raw pipe. However, especially when the raw pipe is a welded pipe, the roundness of the raw pipe itself is poor, and when the raw pipe is attached to the mold, the conventional O-ring damages the O-ring, and the O-ring is damaged. Has a problem with his life.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to form a bellows by hydraulic forming using a straight tube.
It is an object of the present invention to provide a bellows molding method and a device thereof, which make the device compact, reduce the processing force required for molding, and enable stable sealing. Another object of the present invention is to provide a sealing mechanism that facilitates attachment / detachment of a raw tube and a molded product.

[0014]

In order to achieve the above object, the most basic structure of the bellows molding method according to the present invention is to seal both open ends of a bellows forming shell with a mold. A core for guiding the mold is provided, and the element pipe is surrounded by a plurality of split molds having the same axial center as the element pipe, and a hydraulic pressure is applied to the inside of the element pipe, whereby In the bellows molding method of molding a bellows by applying a force in an axial direction to the mold after bulging a part along the plurality of split molds, the core contacts one end of the raw pipe. The mold is adapted to expand and contract between the mold and the mold in contact with the other end.

In order to achieve the above object, the second structure of the bellows molding method according to the present invention is to seal both open ends of a straight tubular blank for forming the bellows with a mold, A core for guiding the mold is provided, and the element tube is surrounded by a plurality of split molds having the same axis as the element tube, and a hydraulic pressure is applied to the inside of the element tube, thereby part of the element tube is In a bellows molding method of molding a bellows by applying an axial force to the mold after swelling along the plurality of split molds, the core is inside the sealed raw tube. , One of which is fixed to one mold that contacts the end of the tube,
The other is an expandable core having a piston and a cylinder in contact with the other die in contact with the end of the shell, and having a hydraulic chamber inside the core. After swelling along the plurality of split molds, the mold in which the base pipe and the expansion / contraction core are in contact with each other in the axial direction in a state in which a hydraulic pressure is applied to the inside of the base pipe by a secondary process When the base tube is pushed in and the base tube is compressed and deformed, the expansion core is contracted while allowing the hydraulic medium filled in the hydraulic chamber inside the expansion core to escape in cooperation with the mold for pushing in the axial direction. It is made by forming a bellows.

Further, in order to achieve the above object, the most basic structure of the bellows molding apparatus according to the present invention is a mold for sealing both open ends of a raw tube for forming the bellows, and the mold. A core for guiding, a plurality of split molds that surround the raw pipe on the same axis as the raw pipe, and a hydraulic pressure is applied to the inside of the raw pipe to cause a part of the raw pipe to run along the split molds. In a bellows molding apparatus provided with a liquid pressure supply means for swelling and a pressurizing means for applying a force in an axial direction to the split mold, the core has a mold contacting one end of the shell and a mold for the other. An expansion / contraction core is composed of a cylinder fixed to one mold and a piston which is in contact with another mold and slides in the cylinder between the mold contacting the end.

Furthermore, in order to achieve the above object,
A second configuration of the bellows molding apparatus according to the present invention is a mold for sealing both open ends of a straight tubular raw pipe, and a hydraulic medium for expanding the raw pipe inside the raw pipe. A first die having a hydraulic pressure supply hole for supplying the liquid, and a second metal die having a vent hole for removing air existing in the raw pipe when filling the hydraulic medium in the raw pipe. A mold, a core for guiding the mold, a hydraulic pressure supply means for supplying a hydraulic medium to the first mold, and the element pipe surrounded by the same axial center as the element pipe. A plurality of split molds for bulging a part of the blank tube by applying hydraulic pressure to the spacers, spacers for arranging the split molds at equal intervals, and the split tube together with the blank tube partially bulged. In a bellows molding apparatus which comprises a pressurizing means for applying a force in an axial direction to the mold, and which molds a bellows from a straight tube by hydraulic molding, the core is Liquid sealed between the first mold and the second mold, which is sealed inside the core by a cylinder fixed to one of the molds and a piston in contact with another mold and sliding in the cylinder. An expansion core forming a pressure chamber, wherein the first mold is a liquid for supplying a passage leading to the inside of the expansion core and a hydraulic medium for swelling the raw pipe into the raw pipe. A die having a pressure supply hole, an insertion portion of the element pipe and a die for sealing the inside of the element tube, an insertion portion of the piston in which the expansion and contraction core is not fixed and a die contacting with the piston,
Sealing means is provided on the piston and the insertion portion of the cylinder in the expandable core.

In addition, the bellows molding apparatus of the present invention for carrying out the above-mentioned molding method using a straight tube-shaped tube has a structure in which the open end of the tube is sealed to form a hydraulic chamber inside the expansion core. A hydraulic pressure supply hole for supplying a hydraulic medium that is smaller than the pressure for expanding the base pipe and that does not allow the piston to descend due to its own weight, and a hydraulic pressure for expanding the base pipe inside the base pipe. There was a first mold with a hydraulic pressure supply hole for supplying a hydraulic medium to the hydraulic chamber inside the expandable core and the internal pipe by sealing the open end of the raw tube as well. A second mold having a vent hole for letting air escape, and between the first mold and the second mold, one is fixed to the mold inside the tube, and the other is fixed to the mold. The expansion core in contact with, the insertion portion of the element tube and the mold for sealing the inside of the element tube, An insertion portion between an unfixed piston and a mold in contact with the piston, a sealing means in the insertion portion of the piston and the cylinder for creating a fluid pressure chamber sealed inside the core in the expandable core, and the fluid pressure supply hole. Hydraulic pressure supplying means for supplying a hydraulic medium to a mold having a mold, a split mold for molding the ridges of the bellows, and a hydraulic pressure in the primary step to swell a part of the raw pipe. Sometimes, it is provided with spacers for arranging the split dies at equal intervals, and means for pushing the split dies in the axial direction at the same time as the blank tube partially bulged after the primary step.

[0019]

DETAILED DESCRIPTION OF THE INVENTION Each embodiment of the present invention will be described below with reference to FIGS. [Embodiment 1] FIG. 1 is a vertical sectional view of a bellows molding apparatus showing an embodiment of the present invention, and FIG. 2 is a vertical sectional view showing a state where bellows molding is performed by the apparatus of FIG. In FIG. 1, reference numeral 1 is a straight tube-shaped tube for forming a bellows, and the material of the tube 1 is stainless steel, aluminum or the like. Reference numeral 2 denotes an upper die (a movable die) related to the second die having the vent hole 7, and 3 denotes a lower die (fixed die) related to the first die having the hydraulic pressure supply holes 8 and 9. Side mold), 4 (collective term for 4a, 4b, 4c, 4d, 4e),
A plurality of split molds which are a mold for enclosing the base pipe 1 at the same axis as the base pipe and applying a hydraulic pressure to the base pipe 1 to bulge a part of the base pipe 1 to form a bellows. 5 is a split mold 4a, 4b,
It is a spacer for arranging 4c, 4d, and 4e at equal intervals.

Reference numeral 11 denotes a cylindrical piston, for example, which has one end in contact with the upper mold 2 and is fitted into the upper mold 2, and 12 is, for example, a cylindrical cylinder whose one end is fixed to the lower mold 3. . The expandable core 15 composed of the piston 11 and the cylinder 12 has a hydraulic chamber 20 therein, and the piston 1 is driven by the hydraulic medium filled in the hydraulic chamber 20.
1 moves and the expandable core 15 expands and contracts. The expandable core 15 has the same axial center as that of the base pipe 1, is located between the upper mold 2 and the lower mold 3, and forms the hydraulic chamber 10 with the base pipe 1.

The bellows molding apparatus shown in FIGS. 1 and 2 will be described in more detail. The upper mold 2 and the lower mold 3 are in contact with the open end of the base pipe 1, and the inside of the base pipe 1 is sealed to form a hydraulic chamber 10. The upper mold 2 has a vent hole 7 for venting air existing in the hydraulic chamber 10 when the hydraulic chamber 10 is filled with the hydraulic medium, and the vent hole 7 is an exhaust provided with an air vent valve 102. It is connected to a pipe. The lower die 3 has a hydraulic pressure supply hole 9 for filling the hydraulic chamber 10 with the hydraulic medium, and a hydraulic pressure for filling the hydraulic chamber 20 in the expansion core 15 with the hydraulic medium. There is a supply hole 8. The hydraulic pressure supply hole 8 is provided with a pump 104, a pressure regulator 105, and a relief valve 10 via a coupler 103.
6, connected to the high-pressure hose 111, the hydraulic pressure supply hole 9 through the coupler 103, the pump 104, the pressure regulator 10
8, the stop valve 109, the relief valve 110, and the high pressure hose 111.

In order to seal the inside of the raw pipe 1 by the upper mold 2 and the lower mold 3 which are in contact with both open ends of the raw pipe 1, the ring-shaped hollow elastic body 22 is used for sealing. Further, the piston 11 forming the expandable core 15 is the expandable core 1
The hydraulic chamber 20 inside 5 is sealed, and the O-ring 21 seals with the cylinder 12 in order to move the piston 11. Further, the piston 11 is sealed by the O-ring 21 so that the expandable core 15 is not affected by the hydraulic medium filled in the hydraulic chamber 10 even in the portion in contact with the upper mold 2. Reference numeral 60 indicated by a large arrow indicates a slider of the press machine, and the upper mold 2 is pushed in in the axial direction by pressing with a press.

First, in the expandable core 15, the cylinder 12 is attached to the lower mold 3, and at this time, the position of the piston 11 is at the lowermost position and is in contact with the lower mold 3.
Next, the blank tube 1 is attached to the lower mold 3 in such a manner that the core tube 1 has the same axis as the expansion core 15, and the split molds 4a, 4b, 4c, 4d,
4e are set so as to be arranged at equal intervals using the spacers 5, and the upper die 2 is attached to seal the inside of the raw tube 1 to form the hydraulic chamber 10. After that, a hydraulic medium is supplied to the expansion / contraction core 15 by the pump 104 and the pressure regulator 105 to raise the piston 11 of the expansion / contraction core 15 until it comes into contact with the upper mold 2, and the liquid inside the expansion / contraction core 15 is reached. Forming a pressure chamber 20,
The inside of the hydraulic chamber 20 is held at a constant pressure so that the piston 11 does not descend, and the hydraulic chamber 20 is fitted into the upper mold 2.

As a primary step, the stop valve 109 is opened to supply the hydraulic medium to the hydraulic chamber 10 inside the raw pipe 1 by low-pressure water supply, and when the hydraulic medium flows out from the ventilation hole 7, the air vent valve 102 And stop valve 109 at the same time
Also close to temporarily stop the supply of hydraulic medium. After that, the pump 104 and the pressure adjuster 108 continue to supply the hydraulic medium to the hydraulic chamber 10 inside the raw pipe 1 to increase the internal pressure of the hydraulic chamber 10 to partially remove the raw pipe 1 from the raw pipe 1. The ridges are formed by bulging along split dies 4a, 4b, 4c, 4d, and 4e that surround the element tube 1 in the same axis, and the supply of the hydraulic medium is stopped.

Next, as a secondary step shown in FIG.
The spacer 5 between a, 4b, 4c, 4d, and 4e is removed, and the upper mold 2 is pressed by the slider 60 of the press machine in the axial direction while the hydraulic pressure is being applied to the inside of the raw tube 1. The base tube 1 that is partially bulged is compressed and deformed. At this time, in conjunction with the upper mold 2, the split mold 4 that surrounds the piston 11 of the expandable core 15 and the base pipe 1 in the same axis
a, 4b, 4c, 4d and 4e also move.

When the piston 11 of the expandable core 15 descends, the volume of the hydraulic chamber 20 inside the expandable core 15 decreases and the pressure acting on the inside increases, so that the relief valve 106 causes the hydraulic chamber 20 to move. Adjust so that the internal pressure of is constant. Similarly, when the base tube 1 that is partially bulged by the upper mold 2 is compressed and deformed, the hydraulic chamber 10 inside the base tube 1 is compressed.
Since the volume is decreased and the pressure acting on the inside of the raw pipe 1 is increased, the relief valve 109 is used to adjust the inside of the hydraulic chamber 10 to be constant.

After the completion of molding, the slider 60 of the pressing machine pushed in the axial direction is unloaded, and remains in the hydraulic chamber 20 inside the expandable core 15 and the hydraulic chamber 10 inside the raw pipe 1. All the hydraulic medium escapes, the upper mold 2 and the split molds 4a, 4b, 4c, 4d, 4e are removed, and the bellows, which is a molded product, is taken out.

In the embodiment shown in FIG. 1, the upper die 2
Although the recessed portion is provided so that the piston 11 of the expandable core 15 can be fitted therein, an example in which such a recessed portion is not provided will be described below. [Embodiment 2] FIG. 3 is a longitudinal sectional view of a bellows molding apparatus showing another embodiment of the present invention. In the figure, those having the same reference numerals as those in FIG. 1 are the same as those in the previous embodiment, and therefore their explanations are omitted. The device shown in FIG. 3 is different from the device shown in FIG. 1 in that the piston 11 of the expansion / contraction core 15 is different.
Is in contact with the lower surface of the upper mold 2A so as to abut.

Here, the upper surface of the piston 11 and the upper mold 2A
If the bottom surface of the
When a slight gap is created between the upper surface of the piston 11 and the lower surface of the upper mold 2A, the hydraulic medium filled in the hydraulic chamber 10 inside the raw tube 1 enters and the hydraulic pressure is increased. As a result, the expandable core 15 does not serve as a core. Therefore, a ring-shaped groove is provided on the upper surface of the piston 11, and the O-ring 25 is fitted into the groove, and the expandable core 1
By applying hydraulic pressure by the hydraulic medium filled in the hydraulic chamber 20 inside 5, the upper mold 2A is pressed against the lower surface of the upper mold 2A while pressing the upper surface of the piston 11 having the O-ring 25 attached thereto. The piston 11 is moved in conjunction therewith. Even with such a bellows forming apparatus, as shown in FIGS.
The same effects as those of the embodiment shown in are obtained.

[Third Embodiment] FIG. 4 is a vertical cross-sectional view of a bellows molding apparatus showing still another embodiment of the present invention. In the figure, those having the same reference numerals as those in FIG. 1 are the same parts as those in the embodiment shown in FIG. In the device shown in FIG. 4, the expandable core 1 is similar to the device shown in FIG.
Although the upper surface of the piston 11 of 5 corresponds to the lower surface of the upper mold 2A, it is not affected by the hydraulic pressure due to the hydraulic medium filled in the hydraulic chamber 10 inside the base tube 1. The position of the O-ring 26 thus attached is at the end of the upper surface of the piston 11, and it is considered that the O-ring 26 is not affected by the hydraulic pressure more than in the case of FIG.

[Fourth Embodiment] FIG. 5 is a vertical cross-sectional view of a bellows molding apparatus showing still another embodiment of the present invention. In the figure, those having the same reference numerals as those in FIG. 1 are the same parts as those in the embodiment shown in FIG. Figure 1 above
In the device shown in FIG. 4 to FIG. 4, the expandable core 15 is composed of the piston 11, the cylinder 12 and the hydraulic chamber 20, but in the device shown in FIG. 5, the upper mold 2 and the piston 11 in FIG. An integrated mold 51 having a structure in which the above is integrated is used.

The integral mold 51 is in contact with one open end of the base tube 1 to seal the inside of the base tube 1 and at the same time the expandable core 1
It also plays the role of a movable piston of 5A. Further, in this case, the portion to be sealed is smaller than that of the respective devices shown in FIGS. 1 to 4, and a constant pressure is applied by the hydraulic medium filled in the hydraulic chamber 20 to move the piston 11 to the upper mold. Since there is no need to press it against 2, there is no need to fill the hydraulic chamber 20 with hydraulic medium, and there is no need for the pressure regulator 105 and the relief valve 106 as shown in FIGS.
Air in the hydraulic chamber 20 may be released through the hydraulic pressure supply hole 8.
However, when attaching and detaching the blank pipe and the molded product, the integrated mold 51
A wide frontage is required because the lower surface of the must be raised.

[Embodiment 5] FIG. 6 is a vertical sectional view of a bellows molding apparatus showing still another embodiment of the present invention. In the figure, those having the same reference numerals as those in FIG. 1 are the same parts as those in the embodiment shown in FIG. In the device shown in FIG. 6, as with the previous devices shown in FIGS. 1 to 4, the expansion / contraction core 15B includes a piston 11B and a cylinder 12B.
And an oil pressure chamber 20, but no O-ring is used on the upper surface of the piston, and the configuration of the device is close to that of FIG.
The piston 11B is fixed to the upper mold 2 with a screw 30. However, the sealing material 31 is sandwiched between the upper surface of the piston 11B and the lower surface of the upper mold 2A, and is not affected by the hydraulic pressure of the hydraulic medium filled in the hydraulic chamber 10 inside the raw tube 1. I am trying.

Further, similar to the device shown in FIG. 5, the hydraulic chamber 2
Since it is not necessary to press the piston 11 against the upper mold 2A by applying a constant pressure with the hydraulic medium filled with 0, it is not necessary to fill the hydraulic chamber 20 with the hydraulic medium. The pressure regulator 105 and the relief valve 106 as in each of the above-mentioned devices are not necessary, and the air in the hydraulic pressure chamber 20 may be released through the hydraulic pressure supply hole 8. However, a wide frontage is required when attaching and detaching the raw pipe and the molded product. Alternatively, it is necessary to remove the screw 30 after the completion of molding and raise the upper mold 2A, and first attach the piston 11B to the upper mold 2A with the screw 30 before starting the molding. In FIG. 6, the screw 3
Although 0 indicates one, the piston 11B may be fixed to the upper mold 2A with a plurality of screws.

[Sixth Embodiment] FIG. 7 is a vertical cross-sectional view of a bellows molding apparatus showing still another embodiment of the present invention. In the figure, those having the same reference numerals as those in FIG. 1 are the same parts as those in the embodiment shown in FIG. The expansion / contraction core 15C of the apparatus shown in FIG. 7 is a multi-stage cylinder having a bamboo-like shape including a piston 11C, a cylinder 12, an intermediate cylinder 13 and a hydraulic chamber 20. Although the cylinder 12 is fixed to the lower mold 3, the piston 11C and the intermediate cylinder 13 can move freely and can adapt to the length of the raw tube 1 with good adaptability.

In the apparatus shown in FIG. 7, when the piston 11C and the intermediate cylinder 13 are at the lowest position, the blank tube and the molded product can be easily attached and detached. Also, the number of cylinders forming the steps of the expandable core 15C can be increased, but as the number of steps increases, the diameter of the piston 11C in contact with the upper mold 2C becomes smaller, and the diameter of the piston 11C in contact with the upper mold 2 becomes smaller. , The upper mold 2C is the hydraulic chamber 1 inside the tube 1.
Since it affects the hydraulic pressure receiving area of the hydraulic medium filled with 0, the effect of the core becomes smaller as the diameter of the piston 11C becomes smaller.

In each of the apparatuses shown in FIGS. 1 to 7, the raw tube 1 and the upper die 2 or the integral die 5 which is in contact with the open end thereof.
In order to seal the hydraulic medium filled in the hydraulic chamber 10 inside the raw tube 1 between the lower mold 1 and the lower die 3, a ring-shaped hollow elastic body 22 is used for sealing. Here, details of the ring-shaped hollow elastic body 22 will be described with reference to FIGS. 8 and 9. [Embodiment 7] FIG. 8 is an enlarged cross-sectional view showing a state in which a ring-shaped hollow elastic body is attached to a mold, and FIG. 9 shows expansion of the ring-shaped hollow elastic body when the mold is fitted to a raw pipe. It is an expanded sectional view showing the state where it was made to seal.

In FIGS. 8 and 9, 22 is a ring-shaped hollow elastic body having a space 29. FIG. 8 shows a state in which the ring-shaped hollow elastic body 22 having the space 29 is set in the groove 2a provided in the upper mold 2 in the circumferential direction. At this time, the space 29 is not filled with anything. In FIG. 9, after fitting the raw pipe 1 into the upper mold 2, in order to seal the hydraulic medium filled in the hydraulic chamber 10 inside the raw pipe 1 between them so as not to enter, Vent 2
A pressure medium is injected into the inner space 29 of the ring-shaped hollow elastic body 21 through 8 to expand the ring-shaped hollow elastic body 22 and apply an internal pressure P to perform sealing.

After the completion of the bellows molding, the molded product is taken out by removing the pressure medium injected into the internal space 29 of the ring-shaped hollow elastic body 22. Generally, in the case where a solid O-ring is generally applied to the seal, the O-ring is damaged when the raw pipe is attached and the molded product is taken out. In the present invention, by using the ring-shaped hollow elastic body 22 shown in FIGS. 8 and 9, it is possible to easily attach and detach the raw pipe and the molded product.

In each of the above-described embodiments, for example, in FIG. 1, the expansion / contraction core 15 fills the hydraulic chamber 20 inside with the hydraulic medium to move the piston 11 to the upper mold 2 at a constant pressure. Although it is pressed, an elastic member such as a spring may be attached to the hydraulic chamber 20 instead of supplying the hydraulic medium. However, in this case, since the spring is inserted into the hydraulic chamber 20 when the cylinder 12 of the expandable core 15 is fixed to the lower mold 3, the position of the piston 11 is different from that when the hydraulic medium is applied to the upper part. Yes, when the upper mold 2 is pushed in the axial direction through a primary process after being fitted to the upper mold 2, the piston 11 descends in cooperation with the upper mold 2 to move the spring in the hydraulic chamber 20. Shrinks, and after completion of molding, slider 60 of press machine
When the upper die is lifted by unloading the piston, the piston 11 returns to its original position because the spring in the hydraulic chamber 20 is stretched. In this case, there are some difficulties in terms of durability of the spring itself and removal of the molded product for mounting the raw tube. Further, in the above-described embodiment, the example in which only one pump is used as the hydraulic pressure supply means has been described, but it goes without saying that a plurality of pumps may be provided and a high pressure pump and a low pressure pump may be used separately.

[0041]

As described in detail above, according to the present invention, when a bellows is formed by hydraulic forming using a straight tube, the device is compact and the processing required for the forming is performed. It is possible to provide a bellows molding method and apparatus that reduce force and enable stable sealing. Further, according to the present invention, it is possible to provide a sealing mechanism that facilitates attachment and detachment of the raw pipe and the molded product.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a bellows molding apparatus showing an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a state where bellows molding is performed by the apparatus of FIG.

FIG. 3 is a vertical sectional view of a bellows molding apparatus showing another embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view of a bellows molding apparatus showing still another embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view of a bellows molding apparatus showing still another embodiment of the present invention.

FIG. 6 is a vertical cross-sectional view of a bellows molding apparatus showing still another embodiment of the present invention.

FIG. 7 is a vertical cross-sectional view of a bellows molding apparatus showing still another embodiment of the present invention.

FIG. 8 is an enlarged cross-sectional view showing a state in which a ring-shaped hollow elastic body is attached to a mold.

FIG. 9 is an enlarged cross-sectional view showing a state in which the ring-shaped hollow elastic body is expanded and sealed when the die is fitted to the raw tube.

FIG. 10 is a vertical cross-sectional view showing the structure of a bellows molding apparatus using a conventional core.

11 is a cross-sectional view showing a state where bellows molding is performed by the apparatus of FIG.

[Explanation of symbols]

1 ... Element pipe, 2, 2A, 2C ... Upper mold, 3 ... Lower mold, 4,
4a, 4b, 4c, 4d, 4e ... Split mold, 5 ... Spacer,
7, 28 ... Vent hole, 8, 9 ... Hydraulic pressure supply hole, 10, 20 ...
Hydraulic chamber, 11, 11B, 11C ... Piston, 12 ... Cylinder, 13 ... Intermediate cylinder, 15, 15A, 15B, 1
5C ... Expandable core, 22 ... Ring-shaped hollow elastic body 21, 21
5, 26, 27 ... O-ring, 29 ... Space, 30 ... Screw,
31 ... Sealing material, 51 ... Integrated mold, 60 ... Press machine slider, 102 ... Air bleeding valve, 104 ... Pump, 10
5, 108 ... Pressure regulator, 106, 110 ... Relief valve, 109 ... Stop valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiko Kaiki 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Kokubun Plant, Hitachi, Ltd. (72) Inventor Motoo Oga 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture No. 1 Inside the Kokubun Plant of Hitachi, Ltd. (72) Inventor Satoru Shirata 1-1-1 Kokubuncho, Hitachi City, Ibaraki Inside the Kokubun Plant of Hitachi Ltd.

Claims (9)

[Claims] 1. A plurality of split molds, each of which has a core for sealing the open ends of a blank tube for forming a bellows and which guides the mold, and which has the same axis as the core tube. By applying a hydraulic pressure to the inside of the raw pipe so as to bulge a part of the raw pipe along the plurality of split molds, by applying an axial force to the mold. A bellows molding method for molding a bellows, wherein the core expands and contracts between a mold in contact with one end of the shell and a mold in contact with the other end. 2. A straight tube-shaped tube for forming a bellows is sealed with a mold at both open ends thereof, and has a core for guiding the mold, and the tube is provided with a plurality of cores having the same axial center as the tube. As surrounded by the split mold, by applying a hydraulic pressure to the inside of the raw pipe, after bulging a part of the raw pipe along the split mold, an axial force to the mold. In a bellows molding method for molding a bellows by adding the core, the core is inside the sealed raw tube, one of which is fixed to one of the molds in contact with the end of the raw tube, and the other of which is the raw tube. An expanding and contracting core having a hydraulic chamber inside the core, which constitutes a piston and a cylinder in contact with the other mold contacting the end of the core. After swelling along with, in the state where liquid pressure is applied to the inside of the raw pipe in the secondary step, When the mold in contact with the expansion core is pushed in the axial direction to compressively deform the raw tube, the expansion core is interlocked with the mold pushed in the axial direction so that the expansion core is a liquid inside the expansion core. A bellows molding method, characterized in that a bellows is molded while shrinking while allowing a hydraulic medium filled in a pressure chamber to escape. 3. A mold for sealing both open ends of a blank tube for forming a bellows, a core for guiding the mold, and a plurality of split molds for surrounding the blank tube on the same axis as the core tube. A liquid pressure supply means for applying a hydraulic pressure to the inside of the raw pipe to bulge a part of the raw pipe along the plurality of split dies, and a pressurizing means for applying an axial force to the split dies. In a bellows molding apparatus provided with, the core is a cylinder fixed to one mold and another mold between the mold contacting one end of the shell and the mold contacting the other end. A bellows molding apparatus comprising an expandable core made up of a piston that contacts a mold and slides in the cylinder. 4. A mold for sealing both open ends of a straight tube-shaped base pipe, wherein a hydraulic pressure supply hole for supplying a hydraulic medium for swelling the base pipe is provided inside the base pipe. A first mold having, a second mold having a vent hole for removing air existing in the base pipe when filling the base pipe with a hydraulic medium, and a core for guiding the mold. And a liquid pressure supply means for supplying a hydraulic medium to the first die, and the element pipe is surrounded by the same axis as the element pipe, and the fluid pressure is applied to the element pipe to apply the fluid pressure to the element pipe. A plurality of split dies for partially bulging, spacers for arranging the split dies at equal intervals, and pressurization for applying an axial force to the split dies together with a partially bulged blank tube. And means,
In a bellows molding device for molding a bellows by hydraulic molding from a straight tubular material pipe, the core is between a first mold and a second mold,
An expandable core that forms a sealed hydraulic chamber inside a core with a cylinder fixed to one of the molds and a piston that is in contact with another mold and slides in the cylinder. The mold is a mold having a passage leading to the inside of the expandable core and a hydraulic pressure supply hole for supplying a hydraulic medium for expanding the raw pipe inside the raw pipe. A sealing means is provided for the insertion part of the die for sealing the inside of the tube, the insertion part of the piston to which the expansion core is not fixed and the die in contact with it, and the insertion part of the piston and the cylinder in the expansion core. A bellows molding device characterized by being provided. 5. The passage communicating with the inside of the expansion core of the first mold is smaller than the pressure for expanding the raw pipe in the hydraulic chamber inside the expansion core, and the piston is not lowered by its own weight. The bellows molding device according to claim 4, wherein the bellows molding device is a hydraulic pressure supply hole for supplying a hydraulic medium. 6. The bellows molding apparatus according to claim 3, wherein the piston of the expandable core is fixed to the second mold. 7. The bellows molding apparatus according to claim 3, wherein the piston of the expandable core is integrally formed with the second mold. 8. The bellows molding device according to claim 3, wherein the cylinders of the expandable core are formed in multiple stages. 9. A ring-shaped hollow elastic body for supplying a pressure medium to the internal space to apply a pressure to perform a sealing is inserted into an insertion portion between the raw pipe and a mold for sealing the inside of the raw pipe. The bellows molding apparatus according to any one of claims 3 and 4, characterized in that.