JP2002295676A - Bellows pipe and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bellows pipe and a manufacturing method therefor, in which a sealing member is axially urged to the inside of a pipe material, hydraulic pressure chamber in the pipe material is sealed using a simple structure, and sufficient sealing property and the pipe material is deformed by a high pressure in the inside. SOLUTION: Circumferential projections 15, projected to an inner surface, are formed on respective sides 14 of a belows forming part 13 of the pipe material 10; respective O-rings 26, provided on draw back molds 20, 21 inserted from both sides of the pipe material 10, are urged to the circumferential projections 15 to position the draw back molds 20, 21 and seal the hydraulic pressure chamber 29, to which high pressure is fed to deform the pipe material 10. Since the pipe material 10 and the draw back molds 20, 21 are fitted loosely, the seal is hardly damaged at insertion of the draw back molds 20, 21; and molding of the bellows pipe, in which linear pipe parts 12, 12 and the bellows molding part 13 are made to an integral structure, is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, an engine which is disposed between an engine and a processing apparatus to guide exhaust gas discharged from the engine to the processing apparatus, and which is caused by heat and vibration transmitted. TECHNICAL FIELD The present invention relates to a bellows tube for relieving excessive stress generated by the bellows and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in an engine, especially a diesel engine, exhaust gas discharged from the engine contains diesel particulates such as soot generated by incomplete combustion. An exhaust system may be provided with a diesel particulate filter (hereinafter abbreviated as DPF) in order to remove the diesel particulates by a filter for processing. Generally, the DPF is arranged in close proximity to the diesel engine, but is manufactured separately from the diesel engine. In order to introduce exhaust gas into the DPF, the engine is driven by an exhaust pipe connected to the exhaust port of the DPF.
Connected to.

However, an exhaust pipe connected to a processing device such as a DPF repeatedly undergoes thermal expansion and thermal contraction due to the passage of high-temperature exhaust gas when the engine is started and stopped. When the vehicle is mounted on a vehicle, repeated compression / tension stress is applied by vibrations generated during the running of the vehicle. Since such repetitive stress causes metal fatigue at seams such as welding pipes, conventionally, a bellows exhibiting spring characteristics is interposed in the exhaust pipe, and the bellows absorbs and relieves the repetitive stress. In addition, fatigue of the connection of the exhaust pipe to the engine and the processing device is avoided, and the durability of the exhaust system is ensured. As shown in FIG. 8, the bellows tube 30
Straight pipe sections 3 provided on the engine side and DPF side, respectively
2 and 32, and flanges 3 for connecting each end of the straight pipe portions 32 and 32 to the exhaust port of the engine and the inlet of the DPF.
6 and 36 and a bellows forming portion 33 for connecting the straight pipe portions 32 and 32 respectively. Straight pipe section 32,3
2 and the bellows forming portion 33 are manufactured as separate bodies, and the ends 34, 34 of the straight pipe portions 32, 32 and the ends 35, 35 of the bellows forming portion 33 are respectively overlapped and fixed by welding. I have. In addition, the flanges 36, 36 also have
2 and 32 are manufactured separately, and are fixed by welding at the joint 37.

In the exhaust pipe connecting the engine and a processing device such as a DPF, since the bellows pipe 30 is interposed as described above, the repetitive stress caused by heat and vibration is reduced, but the bellows Part 33 and straight pipe parts 32,3
When welding is performed with No. 2, there is still concern about machining of the welded joint surface, resulting in material loss, poor welding, and the like.
To ensure that the exhaust gas is introduced into the processing equipment without causing any leaks, all the manufactured exhaust pipes are checked for leaks to determine whether or not there is any leak. The 100% inspection, which must be performed because of this, is one of the factors that increase the manufacturing cost of the exhaust pipe.

A method of forming a bellows forming part in the middle of a pipe by hydraulic forming is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-27766.
No. 0 discloses this. According to this molding method, as the first molding step, the upper end and the lower end of the metal tube are sealed and clamped and held by the mold, so that the bellows forming area of the metal tube is not moved by the liner. Surrounded by a restrained split mold. The discharge amount of the liquid pressure medium supplied to the inside of the metal tube by the pump is controlled according to the overhang amount of the metal tube detected by the sensor.
When the predetermined overhang amount is detected, the supply of the liquid pressure medium to the inside of the metal pipe is temporarily stopped. In the second molding step, the split metal mold which has been movable by removing the liner is pushed in the axial direction together with the upper mold while maintaining the pressure inside the metal pipe, so that the protruding metal pipe is split. Is further deformed according to the molding shape inside and is formed into a bellows.

A method of drawing an integrally molded flanged bellows tube without the need for welding has been proposed (JP-A-9-239472). According to this method of drawing a bellows with a flange, a hollow cylindrical material having a connection portion for flange processing or screw processing at both ends is rolled into a central cylindrical portion using a spindle machine. The bellows forming portion having a predetermined thickness and a predetermined length is formed by rolling while moving the roller in the lateral direction while pressing the roller.

However, since the pipe material for piping is usually used as it is formed by a hot rolling mill without being subjected to grinding or polishing, both the inner surface and the outer surface exhibit a rolling surface. , Circularity, cylindricity, and surface roughness (smoothness) are low. For this reason, in the above-mentioned method of forming a bellows pipe by hydraulic pressure, sealing when expanding by hydraulic pressure is important, and it is made of a ring-shaped elastic body or the like in order to securely seal the upper and lower molds to the metal pipe. A complicated mechanism including a sealing structure and a clamp structure such as a telescopic ring-shaped mold for preventing the metal tube from being pulled in during molding is used. Moreover, this sealing structure requires multiple seals to enhance the sealing performance, which increases the manufacturing cost and may damage the pre-installed seal when inserting the seal tube due to the long cylindrical portion. There is also.

[0008]

SUMMARY OF THE INVENTION In a bellows tube for forming a bellows by applying a high pressure to the inside of the pipe material to cause the pipe material to plastically deform and to manufacture the bellows, the inner surface of the straight pipe portion is made of a pipe material. The processing accuracy such as roundness, cylindricity, surface roughness, etc. is not high and it has a straight shape, so a sealing structure and a clamp structure are required to press the sealing member radially against the straight inner surface. It gets complicated. Therefore, by simply pressing the sealing member in the axial direction inside the straight pipe portion, the hydraulic chamber formed inside the pipe material is sealed with a simple structure and with sufficient sealing performance, and the pipe material is There is a problem to be solved in that the pipe material is easily deformed while holding the pipe.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and it is possible to determine a forming range of a bellows and to set an internal When a high pressure is applied, a simple seal is provided to prevent the liquid from leaking, the seal is hardly damaged, and the pipe material and the mold fitted to the pipe material are loosely fitted. An object of the present invention is to provide a bellows tube that can ensure sufficient sealing performance with a single seal even when the tube is in a closed state, and a method for manufacturing the same.

[0010]

According to the present invention, there is provided a straight pipe portion provided on both sides in the longitudinal direction, and a bellows forming portion formed integrally with the straight pipe portions between the straight pipe portions, The present invention relates to a bellows tube having a convex ridge formed on an inner peripheral surface on both sides of the bellows forming portion. This bellows pipe has one of the straight pipes connected to an exhaust pipe of a diesel engine, and the other of the straight pipes has a diesel particulate filter for removing particles in exhaust gas discharged from the diesel engine. Connected between the diesel engine and the diesel particulate filter.

According to this bellows pipe, the straight pipe portion and the bellows forming portion are formed integrally without welding. Therefore, an inconvenience such as stress concentration occurring at the welded joint between the straight pipe portion and the bellows forming portion does not occur in the bellows tube. It is possible to press the seal ring provided on the mold against the convex ridge formed on the inner peripheral surface on both sides of the bellows forming part, and from the inside while maintaining the integrity of the pipe material. The bellows can be manufactured by the deformation due to the hydraulic pressure. Also, when this bellows pipe is applied between the diesel engine of the vehicle and the diesel particulate filter, the bellows pipe receives heat from the high-temperature exhaust gas passing through the inside when the engine starts operating, and stops the operation of the engine. As a result, the flow of the exhaust gas stops and the cooling is caused by the cooling, and thus the thermal stress is applied, or the mechanical stress is applied by the vibration generated with the traveling of the vehicle. Is absorbed and relaxed.

Further, according to the present invention, on both sides of a predetermined width region along a longitudinal direction of the pipe material, convex ridges which protrude inside the pipe material are formed, and seals are formed at both ends of the pipe material at both ends. A seal between the pipe material and the shift mold is inserted by inserting a shift mold having a ring and pressing the seal ring against the convex peripheral strip,
The bellows forming portion is formed by deforming the predetermined width region of the pipe material according to a bellows forming die arranged outside thereof by the pressure of the liquid supplied into the pipe material sandwiched between the double-sided molds. And a method for manufacturing a bellows tube. In the method for manufacturing a bellows pipe, the convex circumferential ridge is formed by forming a concave circumferential groove in a corresponding outer peripheral portion of the pipe material by plastic working.

According to this method of manufacturing a bellows pipe, convex ridges are formed on both sides of the bellows forming portion of the pipe material so as to protrude on the inner surface, and a single O-ring is provided in an approaching mold inserted from both sides of the pipe material. As a sealing member,
The protruding ridge is a ridge that does not impede the flow of the fluid that passes through the inside. By pressing the sealing means against the ridge in the axial direction, a simple and complete seal can be obtained, and the sealing ridge is provided. Is held. Since the liquid pressure is applied only to the necessary portion where the bellows should be formed, it is possible to form a bellows tube having a single structure from the straight pipe portion to the bellows forming portion with a press machine having a small clamping force. Further, since the pipe material and the closing mold are loosely fitted, the seal is not easily damaged when the closing mold is inserted. By forming a concave circumferential groove on the outer peripheral portion corresponding to the convex rim of the pipe material by, for example, roll forming for pressing a roll, the convex rim can be easily formed on the inner surface of the pipe material. it can.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a bellows pipe according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a side view showing an embodiment of a bellows tube according to the present invention in a cross section of an upper half, FIG. 2 is a side view of the bellows tube shown in FIG.
FIG. 2 is an enlarged sectional view of a portion indicated by A of the bellows tube shown in FIG. 1.

In FIG. 1, a bellows tube 1 has straight pipe portions 2 on both sides in the longitudinal direction, and both straight pipe portions 2 are formed with a bellows forming portion integrally formed with both straight pipe portions 2. 3 are connected. On both sides 4, 4 of the bellows forming portion 3, convex ridges 5, 5 protruding from the inner peripheral surface of the tube are formed. The end portions of the straight pipe portions 2 are formed on integral flanges 6 having a double structure. Bellows tube 1
From the flanges 6, 6 to the bellows forming portion 3 through the straight pipe portions 2, 2 and both sides 4, 4, an integrated pipe structure formed of one pipe material is provided. Therefore, since there is no weld fixing portion, it is possible to avoid in advance a problem such as metal fatigue which tends to occur peculiarly to the welded portion.

The flanges 6 and 6 have an integral double structure in which the end of the pipe material is enlarged and a part thereof is folded inward. Because of such an integrated double structure,
Flange rigidity is improved. That is, as shown in FIG. 3, the flange 6 is formed by enlarging and deforming the end portion of the straight pipe portion 2 to the outside and folding it inward at the folded portion 8. It is formed by pushing it inside. As shown in FIG. 2, a plurality of mounting holes 7 (only some of them are denoted by reference numerals) are formed in each flange 6 at equal intervals. The flanges 6, 6 are attached to, for example, an exhaust pipe of a diesel engine and an exhaust gas inlet of a DPF, respectively, by inserting and tightening attachment bolts (not shown) into the attachment holes 7. Regarding the flange 6, instead of the double structure shown in FIGS. 2 and 3, a flange having a single-layer structure in which the end portion of the straight pipe portion 2 is simply expanded and deformed outward as conventionally used, A structure in which the flange sealing surface is tightened by a separately manufactured flange ring (not shown) may be used.

Next, a method of manufacturing a bellows pipe according to the present invention will be described with reference to FIGS. FIGS. 4 to 6 are views showing the process of manufacturing the bellows pipe according to an embodiment of the present invention. FIG. 4 is a view showing a state in which a convex ridge is formed on the inner peripheral surface of the pipe material. Is a view showing a state in which a closing mold is inserted into the inside of a pipe material and a bellows forming mold is arranged on an outer peripheral portion, and FIG. 6 is a view showing a state in which a bellows is formed by applying liquid pressure inside the pipe material. .
First, as shown in FIG. 4, a straight pipe material 10 having a circular cross section is prepared, and both sides 14, 14 of a predetermined width region 13 along a longitudinal direction in which a bellows is to be formed between straight pipe portions 12, 12. At 14, the inner peripheral portion 1 of the pipe material 10
For example, convex ridges 15, 15 which protrude in a semicircular shape when viewed in a cross section along the pipe axial direction are formed in 1. Convex circumference 1
5 and 15 can be formed, for example, by subjecting the corresponding outer peripheral portion of the pipe material 10 to roll forming. That is, the pipe material 10 is rolled while being pressed against the outer peripheral portion of the pipe material 10 to plastically deform the pipe material 10 to form the concave circumferential grooves 16, 1.
6 is formed, the inner peripheral portion 1 corresponding to the concave peripheral grooves 16, 16 is formed.
The convex ridges 15, 15 are formed by the bulging deformation occurring in 1. As will be described later, the size of the convex ridges 15 and 15 is as follows.
It is large enough to achieve sealing performance in cooperation with the seal ring, and may be sufficiently small compared to the size of the corrugation of the bellows to be formed. The effect on the passage of fluid is small. As will be described later, the convex circumferential strips 15 on both sides 14 serve to seal the hydraulic pressure during bellows molding.

Next, as shown in FIG.
, Are inserted from both ends. In the illustrated example, the closing mold 20 on the left side of the figure is a solid cylinder, but the closing mold 21 on the right side of the figure is a cylinder formed with a liquid communication hole 22a, as described later. Pipe material 10
As shown in FIG. 7 which is an enlarged view of a seal portion between the molds 20 and 21, the taper tapered from the outer peripheral surfaces 23 and 23 of the tips 22 and 22 of the molds 20 and 21 to the mold tip side. Surfaces 24, 24 are formed. A peripheral groove 25 is formed at a portion where each tapered surface 24 is connected to the outer peripheral surface 23.
An O-ring 26 as a seal ring is fitted and attached to each circumferential groove 25. The O-rings 20 and 21 are drawn toward each other as shown in the drawing (for example, the O-rings 21 are fixed to the machine frame of the manufacturing apparatus and the O-rings 20 are drawn toward the O-rings 21) so that each O-ring 26 is made of a pipe material. As a result, the insertion positions of the dies 20 and 21 with respect to the pipe material 10 are determined, and the pipe material 10 is moved toward the dies 20 and 2.
1 and the pipe material 10 and the closing molds 20, 2
1 is sealed.

Before or after this, a bellows forming die 28 is arranged outside the predetermined width region 13 of the pipe blank 10. The bellows forming mold 28 is composed of a plurality of ring-shaped split molds 28a to 28e which can be separated, and is initially separated and distributed over a straight predetermined width region 13 as shown in FIG. The split molds 28a to 28e are such that when assembled in the axial direction, the shape of the inner periphery matches the shape of the bellows forming portion 3 to be formed on the pipe material 10.

Next, as shown in FIG.
A liquid such as water or oil is supplied to a hydraulic pressure chamber 29 formed inside the pipe material 10 sandwiched between the pipes 1 through a communication hole 22a of a close mold 21 on the right side in the figure. The processing steps after a seal having no liquid leakage between the pipe blank 10 and the closing dies 20 and 21 are obtained are described in the above-mentioned Japanese Patent Application Laid-Open No. 10-2.
The same method as that disclosed in JP 77660 can be employed. Pipe material 10 and dies 20 and 21
Is sealed by O-rings 26, 26, so that the liquid does not leak outside through the gap 27. The bellows is formed by applying a hydraulic pressure of about 1000 to 3000 kgf / cm ² to the hydraulic chamber 29 of the pipe material 10 to plastically deform and expand the pipe material 10. As shown in FIG. 6, the predetermined width region 13 of the pipe material 10 is separated from the split dies 28 a to 28 e which gradually gather by applying an axial force to the pipe material 10 while maintaining the hydraulic pressure in the hydraulic chamber 29. Bellows forming mold 28
And is formed into the bellows forming portion 3 shown in FIG. At this time, the outermost split molds 28a,
Since 28e has a shape that fits into the concave circumferential grooves 16, 16, deformation of the convex circumferential stripes 15, 15 due to the O-ring 26 being pressed is suppressed.

The straight pipe portion 12 of the pipe material 10 being formed is
The two sides 14, 14 and the convex ridges 15, 15 are respectively connected to the straight pipe portions 2, 2, the both sides 4, 4, and the convex ridges 5, 5 in the bellows pipe 1 after the completion of forming shown in FIG. It is supported as it is. The axial force due to the liquid pressure is a value obtained by multiplying the projected area of the pipe by the liquid pressure, and this load is supported by an apparatus frame (not shown) via the closing dies 20 and 21. By forming the convex ridges 15 on the inner peripheral surface 11 of the pipe material 10 in advance, the pipe materials 1
The insertion position within 0 is determined. Further, in the bellows molding, since a liquid pressure is applied only to a necessary portion of the pipe material 10 limited by the convex circumferential strips 5, 5, the bellows molding can be performed by a press machine having a small clamping force.

In the above embodiment, the bellows pipe has been described as being applied as a pipe connecting between the diesel engine and the DPF. However, a processing unit other than the DPF, such as a catalytic purifier, etc. The present invention is also applicable to a device in which these devices are housed inside the bellows tube. Alternatively, other than the engine, the present invention can be applied to any use as long as it is a piping system as well as a severe environment such as heat or vibration.

[0023]

According to the bellows pipe according to the present invention, the straight pipe portion and the bellows forming portion are integrated pipes, so that durability and reliability can be improved. In addition, since the straight pipe portion does not use welding for connection with the bellows forming portion, it is possible to obtain a low-cost pipe having no leak failure and applied between the diesel engine of the vehicle and the DPF. Sometimes, an inexpensive DPF exhaust pipe can be obtained. Further, according to the method for manufacturing a bellows pipe of the present invention, on both sides of the bellows forming portion of the pipe material, convex ridges protruding from the inner peripheral portion are formed, and the pipe is simply inserted into both sides of the pipe material. Since one O-ring is provided as a seal ring, by pressing the seal ring against the convex rim in the axial direction, a molding range is determined for bellows molding, and a simple and complete seal is obtained.
A bellows tube having an integral structure from the straight pipe portion to the bellows forming portion can be formed. Also, since the hydraulic pressure application range when forming the bellows is narrow and the hydraulic pressure only needs to be applied to the required locations, multiplexing and large-scale operation are required to secure the hydraulic pressure at both ends of the conventional approach type. It does not require a large seal such as a diameter, and even a large-diameter and long pipe can use inexpensive equipment such as a small press machine with a small clamping force. Since the amount of pressurized liquid for forming the bellows tube is small, the pump capacity can be small, and the cost of the manufacturing equipment can be kept low. In addition, the cycle time for manufacturing one bellows tube is short, the production amount per unit time is increased, and the production efficiency can be improved. Furthermore, since the pipe material and the closing mold are loosely fitted, even if the processing accuracy such as roundness, cylindricity, and surface roughness of the pipe material is not high, when the closing mold is inserted, the seal It is hard to be damaged.

[Brief description of the drawings]

FIG. 1 is a side view showing an upper half of a bellows tube according to an embodiment of the present invention in cross section.

FIG. 2 is a front view of the bellows tube shown in FIG.

FIG. 3 is an enlarged sectional view of a portion indicated by A of the bellows tube shown in FIG. 1;

FIG. 4 is a diagram showing a state in which a convex ridge is formed on the inner peripheral surface of the pipe material in the method of manufacturing a bellows pipe according to the present invention.

FIG. 5 is a view showing a state in which a shift die is inserted into the inside of the pipe material from the state shown in FIG. 4 and a bellows forming die is arranged on an outer peripheral portion;

FIG. 6 is a diagram showing a state in which a bellows is formed by applying a liquid pressure to the inside of the pipe material from the state shown in FIG. 5;

FIG. 7 is an enlarged view of a seal portion between a pipe material and an approach mold in FIG. 5 or FIG. 6;

FIG. 8 is a side view of a conventional bellows tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bellows pipe 2 Straight pipe part 3 Bellows forming part 4, 4 Side of bellows forming part 5 Convex peripheral line 6 Flange 10 Pipe material 11 Inner peripheral part 13 Predetermined width area 14 Side 15 Convex peripheral line 16 Concave peripheral groove 20, 21 Mold 22 Tip 23 Outer peripheral portion of pipe material 26 Seal ring (O-ring) 28 Bellows mold 28a-28e Split mold 29 Hydraulic chamber

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G004 BA04 EA03 FA04 3H104 JA08 JB02 JC08 JD03 LB01 LB38 LF16 LG02 MA01 3J045 AA14 BA04 CB03 DA02 EA10

Claims (4)

[Claims] 1. A straight pipe portion provided on both sides in a longitudinal direction, and a bellows forming portion formed integrally with the straight pipe portions between the straight pipe portions, on both sides of the bellows forming portion. Is a bellows tube having a raised convex ridge on the inner peripheral surface. 2. The bellows pipe according to claim 1, wherein the pipe is applied to an exhaust pipe. 3. A projecting ridge that protrudes inside the pipe material on both sides of a predetermined width region along the longitudinal direction of the pipe material, and seal rings are provided at both ends of the pipe material at both ends. A liquid supplied to the inside of the pipe material sandwiched between the double-sided dies by inserting a nesting die and pressing the seal ring against the convex rim to seal between the pipe material and the nesting die. And forming the bellows forming portion by deforming the predetermined width region of the pipe material according to a bellows forming die arranged outside the pipe material by the pressure. 4. The method for manufacturing a bellows pipe according to claim 3, wherein said convex circumferential strip is formed by forming a concave circumferential groove by plastic working on a corresponding outer peripheral portion of said pipe blank.