JPH09273421A - Joint and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent leakage of emission gas and the like from an engine from a joint main body and to improve an appearance. SOLUTION: A joint main body 3 is formed of a single cylindrical molded body. The main body 3 is formed into a taper gradually tapering down from the upstream side to the downstream side as a whole. An exhaust pipe connection port 7, to which two exhaust pipes 2 are connected together, is formed in the upstream end of the joint main body 3. A pair of throttle parts 8a, 8b drawn by press molding are formed in the upper part and the lower part of the width directional central part of the exhaust port 7. In a manufacturing method of the joint main body 3, a molding material is spread around its axial line in an expansion process, and the spread molding material is pressed in its radius direction in a pressing process, and the spread part, in the molding material is drawn in the radius direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint in which a plurality of connection pipes are connected to at least one of the connection ports provided at both ends of a joint body, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, as a joint of this type, for example, there is a joint for connecting an exhaust pipe connected to an engine of a two-wheeled vehicle and a joint pipe connected to a muffler. That is, as shown in FIG. 7, the joint body 30 of this joint is composed of first and second concave members 31 and 32, and both concave members 31 and 32 are butted against each other. Each concave member 31, 3
Flange portions 31a and 32a are provided on both side edges of 2 in a protruding manner.
The flange portions 31a and 32a are fixed to each other by fillet welding. The interior of the joint body 30 is tubular because the biconcave members 31 and 32 are fixed to each other. Further, an exhaust pipe connection port 33 is formed at the downstream end of the joint body 30, and the downstream ends of a pair of exhaust pipes 34 are connected to the connection port 33. On the other hand, a joint pipe connection port 35 is formed at the upstream end of the joint body 30, and the joint pipe 36 is connected to the joint pipe connection port 35. And
Exhaust gas emitted from the engine is exhaust pipe 3
4, through the joint body 30 and the joint pipe 36 to a muffler (not shown).

To manufacture the joint body 30, the sheet metal is shirred and then the sheet metal is press-molded by a press die. As a result, the flange portions 31 are provided on both side edges.
Each concave member 31, 32 having a, 32a is molded. Next, the leading edge of each of the flange portions 31a and 32a is trimmed. Thereafter, the concave portions of the both concave members 31 and 32 are opposed to each other and the flange portions 31a and 32a are brought into contact with each other, and in this state, the both flange portions 31a and 32a are fillet welded and fixed to each other.

[0004]

However, in the joint body 30 described above, the flange portion 31 of the biconcave members 31 and 32 is formed.
If the welding process between a and 32a is poor, the flange portion 31a,
There is a possibility that the 32a will not be welded together without a gap. Therefore, the exhaust gas may leak from the defective welding portion. In the case of fillet welding, both flanges 31a,
A welding mark was always left on 32a. Therefore, since such a welding mark is visually recognized from the outside, there is a problem that the appearance is poor.

When manufacturing the joint body 30, shearing of sheet metal, press forming of sheet metal, trimming of flange portions 31a and 32a, biconcave members 31 and 32 are performed.
Many processes such as fillet welding are required. As a result, there has been a problem that the number of steps required for manufacturing increases and the manufacturing cost increases.

Further, when the flange portions 31a and 32a of the biconcave members 31 and 32 are welded to each other, metal particles are scattered during the welding, so that spatter is attached around the flange portions 31a and 32a. Therefore, an additional work process for removing the spatters is required, resulting in an additional number of processes required for manufacturing, resulting in a higher manufacturing cost.

The present invention has been made to solve the above problems. A first object of the present invention is to prevent exhaust gas from an engine from leaking from the joint body and to provide a good appearance. To make it better. The second purpose is to reduce the number of steps required for manufacturing and reduce the manufacturing cost.

[0008]

According to a first aspect of the present invention, first and second connection ports for connecting a connection pipe to the joint body are provided at both ends of the joint body, and both the connection are provided. In a joint in which a plurality of connection pipes are connected to at least one connection port of the ports, the gist is that the joint body is molded from a single tubular molding material. Therefore, according to the invention described in claim 1, for example, when exhaust gas or the like from the engine passes through the inside of the joint body, the exhaust gas does not leak from the joint body.

According to a second aspect of the present invention, there is provided an expanding step of expanding at least one end side opening of the tubular cylindrical forming material around the axis of the forming material, and an opening of the forming material expanded in the expanding step. And a pressing step of pressing the portion in the radial direction thereof. Therefore, according to the invention described in claim 2, in the expanding step, the forming material is expanded around the axis of the same material. Then, in the pressing step, when the expanded forming material is pressed along the radial direction, the expanded portion of the forming material is squeezed in the radial direction.

According to a third aspect of the present invention, in the expanding step, a mandrel movable along the axial direction of the forming material is pushed into the opening of the forming material, so that the opening of the forming material is formed. The point is that it can be expanded. Therefore, according to the invention described in claim 3, in addition to the function of the invention described in claim 2, the core material is pushed into the molding material, so that the molding material is expanded around its axis.

According to a fourth aspect of the present invention, in the expanding step, at least two cores having different diameters are pushed into the opening of the molding material in order from a core having a smaller diameter. The gist is that the opening of the molding material is gradually expanded. Therefore, according to the invention described in claim 4, in addition to the effect of the invention described in claim 3, when the mandrel having a smaller diameter is pushed into the molding material, the molding material expands in the radial direction. To be Then, when the mandrel having the larger diameter is pushed into the forming material, the forming material is further expanded in the radial direction. Therefore, the molding material is gradually expanded through at least two steps.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in a joint connected to an exhaust pipe of a two-wheeled vehicle will be described below with reference to the drawings.

As shown in FIG. 1, an upstream end of an exhaust pipe (connection pipe) 2 is connected to an engine 1 of a motorcycle. Although only one exhaust pipe 2 is shown in FIG. 1, four exhaust pipes 2 are connected to the engine 1. The downstream ends of the two exhaust pipes 2 are connected to the upstream ends of one joint pipe (connection pipe) 4 via the joint body 3. That is, as shown in FIG. 3, two exhaust pipes 2 are assembled for each joint body 3. A muffler 5 is connected to the downstream end of the joint pipe 4. Exhaust gas from the engine 1 is exhausted to the outside via the exhaust pipe 2, the joint body 3, the joint pipe 4 and the muffler 5.

As shown in FIGS. 2 and 3, the joint body 3 is
Is formed from a single molding material (shown in FIG. 4) 6 described later, and the joint body 3 is formed in a tubular shape. That is, the entire joint body 3 is formed so as to gradually become thinner from the upstream side to the downstream side. In other words, the upstream side of the joint body 3 expands in the width direction of the joint body 3.

At the upstream end of the joint body 3, an exhaust pipe connection port (first connection port) 7 for collectively connecting the two exhaust pipes 2 is formed. A pair of narrowed portions 8a and 8b narrowed by press molding are formed above and below the central portion in the width direction of the exhaust pipe connection port 7, and the narrowed portions 8a and 8b are separated by a predetermined distance. The exhaust pipe connecting port 7 is a pair of connecting portions 9a and 9b with the throttle portions 8a and 8b as boundaries, and the inner diameters of the connecting portions 9a and 9b are equal to the outer diameters of the exhaust pipes 2. ing. That is, the downstream end of each exhaust pipe 2 is inserted into each connecting portion 9a, 9b. Further, a step portion 7a is formed on the inner end of the exhaust pipe connection port 7 along the periphery thereof.
The downstream end of the exhaust pipe 2 is connected to each connecting portion 9
When inserted into a and 9b, the downstream end of each pipe 2 is positioned by abutting against the stepped portion 7a.

On the other hand, a joint pipe connection port (second connection port) 10 for connecting the joint pipe 4 is formed at the downstream end of the joint body 3. The downstream end of the joint pipe 4 is inserted into the joint pipe connection port 10. Also, joint pipe connection port 1
At the inner end of 0, a step portion 10a is formed along the peripheral edge thereof. Then, when the downstream end of the joint pipe 4 is inserted into the joint pipe connection port 10, the downstream end of the pipe 4 is positioned by being brought into contact with the step portion 10a.

Next, various mold apparatuses for manufacturing the joint configured as described above will be described. The joint body 3 includes a first expanding mold device 11 shown in FIGS. 4 (a) and 4 (b), a second expanding mold device 12 shown in FIGS. 5 (a) and 5 (b), and FIG. (A) to (c) shown in FIG.
3 is manufactured. First, the first expanding mold device 11 will be described. As shown in FIGS. 4 (a) and 4 (b), the first expanding die device 11 includes the first die 1
4 and a first mandrel 15 that can be brought into and out of contact with the first die 14. A first molding hole 16 extending in the vertical direction is formed in the first die 14. A lower portion of the first molding hole 16 is a circular hole-shaped insertion portion 16a, and the diameter of the insertion portion 16a is equal to the outer diameter of the molding material 6. Then, the insertion portion 16
The lower part of the molding material 6 can be inserted into the inside of a, and in this insertion state, the molding material 6 is supported in an upright state.

Further, an inclined portion 16b is formed from the central portion of the first molding hole 16 to its upper portion. This inclined portion 16
b is expanded at a predetermined inclination angle as it goes upward from the upper edge of the insertion portion 16a.

On the other hand, the first mandrel 15 is formed in a cylindrical shape, and the press-fitting portion 1 having a truncated cone shape is formed at the lower end thereof.
5a are formed. The press-fitting portion 15a has a shape corresponding to the inclined portion 16b of the first molding hole 16. Then, with the molding material 6 inserted in the insertion portion 16a of the first molding hole 16, the first mandrel 15 approaches the first die 14 and is pushed into the upper opening 6a of the molding material 6. As a result, the molding material 6 can be expanded along the inclined portion 16b from the central portion to the upper end.

Next, the second expanding die unit 12 will be described. As shown in FIGS. 5A and 5B, the second expansion die device 12 includes a second die 17 and a second mandrel 18 that can be brought into contact with and separated from the second die 17. It consists of and. A second molding hole 19 extending in the vertical direction is formed in the second die 17. The lower portion of the second molding hole 19 is a circular hole-shaped insertion portion 19a,
The diameter of this insertion portion 19a is equal to the outer diameter of the molding material 6. That is, the insertion portion 19a of the second molding hole 19 has the same diameter as the insertion portion 16a of the first molding hole 16. The lower part of the molding material 6 can be inserted into the insertion portion 19a, and in this insertion state, the molding material 6 is supported in an upright state.

The central portion of the second molding hole 19 is an inclined portion 19b, and this inclined portion 19b is the insertion portion 1 described above.
As it goes upward from the upper edge of 9a, it gradually expands at a predetermined inclination angle. The inclination angle of the inclined portion 19b of the second forming hole 19 is wider than the inclination angle of the inclined portion 16b of the first forming hole 16.
Further, the upper portion of the second molding hole 19 is a circular hole-shaped vertical portion 19c, and the diameter of the vertical portion 19c is larger than the diameter of the insertion portion 19a.

On the other hand, the second mandrel 18 is formed in a cylindrical shape, and its diameter is larger than that of the first mandrel 15. A press-fitting portion 18 a having a truncated cone shape is formed at the lower end of the second mandrel 18.
The diameter of a becomes smaller toward the tip side of the second mandrel 18. The press-fitting portion 18a has a shape corresponding to the inclined portion 19b and the vertical portion 19c of the second molding hole 19. Then, with the molding material 6 inserted in the insertion portion 19a of the second molding hole 19, the second mandrel 18 approaches the second die 17 and is pushed into the upper opening 6a of the molding material 6. As a result, the molding material 6 can be expanded along the inclined portion 19b and the vertical portion 19c from the central portion to the upper end. Next, the drawing die device 13
Will be described. As shown in FIGS. 6A and 6B,
The drawing die unit 13 is provided with a lower die 20 and an upper die 21 so that the two dies 20, 21 can approach and separate from each other. The upper surface of the lower mold 20 and the lower surface of the upper mold 21, that is, both molds 2
The aperture recesses 22 and 23 are formed on the surfaces of the apertures 0 and 21 that face each other, and the aperture recesses 22 and 23 are arranged to face each other in the vertical direction. The aperture recesses 22 and 23 of both molds 20 and 21 are
A pair of arc portions 22a, 23a and both arc portions 22a, 23
It is composed of projections 22b and 23b formed between a and a. The arcuate portions 22a and 23a have the same radius of curvature and correspond to the outer peripheral surface of the exhaust pipe 2. The protrusions 22b and 23b correspond to the groove 2a between the exhaust pipes 2.

As shown in FIGS. 6 (a) to 6 (c), the drawing die device 13 is provided with first and second cores 24 and 25, and both cores 24 and 25 are the above-mentioned molds. It can be arranged between 20 and 21. The first core 24 can be inserted from the upper opening 6a of the molding material 6 expanded by the expanding mold devices 11 and 12. First core 2
The tip side of 4 (the lower side of FIG. 6 (c)) is gradually thin and can be inserted into the upper opening 6a of the molding material 6. A pair of recesses 24a corresponding to the protrusions 22b and 23b of the molds 20 and 21 are formed on the upper and lower surfaces of the first core 24. The outer peripheral surface of the first core 24 excluding the recess 24a is formed by the circular arc portions 22a, 2
It corresponds to 3a. A step portion 24b is formed along the outer periphery of the tip of the first core 24.

On the other hand, the second core 25 can be inserted from the lower opening 6b of the molding material 6 which has not been expanded by the expanding die units 11 and 12. Second core 25
A step portion 25b is formed along the outer periphery of the tip portion (upper side in FIG. 6C) of the. Then, when the molds 20 and 21 are approached with both cores 24 and 25 inserted and arranged in the openings 6a and 6b of the molding material 6, the molding material 6
Is to be press molded.

Next, a method of manufacturing a joint, which is carried out by using the mold apparatus having the above-mentioned structure, will be described. (Temporary Expansion Step) First, the temporary expansion step will be described. In this step, the first expanding die device 11 is used. As shown in FIG. 4A, the tubular forming material 6 is set in the first die 14. That is, the first core 15 and the first
The lower end of the molding material 6 is inserted into the insertion portion 16a of the first molding hole 16 in a state where the molding material 6 and the die 14 are spaced apart from each other, and the molding material 6 is held in an upright state. In this state, as shown in FIG. 4 (b), when the first mandrel 15 approaches the first die 14, the first mandrel 15 moves from the upper opening 6 a of the forming material 6 to the inside. Be pushed into. Then, the approaching / separating operation of the first mandrel 15 with respect to the first die 14 is repeated 2-3 times. Then, the upper opening 6a of the molding material 6 is expanded around the axis C thereof. That is,
The first molding hole 16 is expanded so as to come into contact with the inner surface of the inclined portion 16b. Then, the expanded forming material 6 is extracted from the first die 14 and the main expanding step is performed.

(Main Spreading Step) Next, the main spreading step will be described. In this step, the second expanding mold device 12 is used. As shown in FIG. 5A, the molding material 6 that has been molded in the temporary expanding step is set in the second die 17. That is, with the second mandrel 18 and the second die 17 spaced apart from each other, the lower end of the molding material 6 is inserted into the insertion portion 19a of the second molding hole 19 to form the molding material 6
Hold it upright. In this state, as shown in FIG. 5 (b), when the second mandrel 18 approaches the second die 17, the second mandrel 18 causes the upper opening 6 of the forming material 6 to come into contact.
It is pushed in from a. And the second die 17
The approaching / separating operation of the first mandrel 15 with respect to is repeated 2-3 times. Then, the upper opening 6a of the forming material 6 is further expanded around its axis C than in the temporary expanding step.
That is, the inclined portion 19b of the second molding hole 19 and the vertical portion 1
It is expanded so as to contact the inner surface of 9c. After that, the expanded molding material 6 is extracted from the second die 17,
Move to the pressing process.

(Pressing Step) Next, the pressing step will be described. In this step, the drawing die device 13 is used. As shown in FIGS. 6A and 6C, in a state where the upper mold 21 and the lower mold 20 are separated from each other, the molding material 6 that has been molded in the temporary expanding process and the main expanding process is used in both molds 20 and 21.
Place between. Then, the first core 24 is inserted into the upper opening 6a of the molding material 6 and the second core 25 is inserted into the lower opening 6b of the molding material 6 so that both cores 24, 2
Butt the end faces of the five. In this state, FIG.
As shown in (b), when the two molds 24, 25 are brought close to each other, the molding material 6 is pressed in the radial direction. By this press, the narrowed portions 8a and 8b are molded. or,
The step portions 7a and 10a are also molded together with this press. Therefore, the narrowed portions 8a, 8b and the stepped portions 7a, 1
The joint body 3 is manufactured by molding 0a.

Therefore, in the joint manufactured by the above-mentioned method, when the exhaust gas from the engine 1 passes through the joint body 3, the joint body 3 is press-formed with the forming material 6 and is welded. Since there is no joint, exhaust gas does not leak from the side portion of the joint body 3.

This embodiment has the following effects (1) to (6). (1) By molding the joint body 3 by press-molding the tubular molding material 6, the joint seam in the middle of the joint body 3 is completely eliminated. Therefore, when the exhaust gas from the engine 1 passes through the inside of the joint body 3, it can be reliably prevented from leaking to the outside.

(2) The joint body 3 is formed by press-forming the forming material 6 so that no welding mark is left on the outer surface of the joint body 3. Therefore, the appearance can be improved.

(3) When manufacturing the joint body 3,
After the forming material 6 was expanded by the temporary expanding step and the main expanding step, the forming material 6 was pressed by the pressing step to form the narrowed portions 8a and 8b and the stepped portions 7a and 10a. Therefore, unlike the conventional technology, the shearing process of the sheet metal,
The steps such as the trimming step and the welding step after pressing the sheet metal can be omitted. Therefore, the number of steps required to manufacture the joint body 3 can be reduced, and the manufacturing cost can be reduced.

(4) When manufacturing the joint body 3,
Since the welding process is omitted, spatter accompanying welding does not adhere to the outer surface of the joint body 3. Therefore, the number of steps for removing spatter can be reduced, and thus the manufacturing cost can be further reduced.

(5) In the temporary expanding step or the main expanding step, the cores 15 and 18 are placed in the upper opening 6a of the forming material 6.
By pushing in, the molding material 6 can be expanded around its axis C. Therefore, the molding material 6 can be spread evenly around the axis C, and the delicate joint body 3 can be manufactured.

(6) The forming material 6 was gradually expanded in the temporary expanding step and the main expanding step. That is, in the temporary expanding step, after the first mandrel 15 is pushed into the upper opening 6a of the forming material 6 to expand it, in the main expanding step, the first core 15 is also inserted into the upper opening 6a of the forming material 6. The molding material 6 is expanded by pushing in the second mandrel 18 having a diameter larger than that of the gold 15. Therefore, the molding material 6 can be gradually expanded without applying an excessive force. Therefore, the molding material 6
It is possible to reliably prevent wrinkles and cracks on the outer surface of the.

The present invention may be configured as follows in addition to the above embodiment. (A) In the above embodiment, the joint body 3 is connected to the exhaust pipe 2 of a two-wheeled vehicle, but it may be connected to the exhaust pipe 2 of a three-wheeled vehicle or a four-wheeled vehicle. Also, the joint body 3 is not limited to the exhaust pipe 2,
It may be connected to the intake manifold or the exhaust manifold.

(B) In the above embodiment, the two exhaust pipes 2 are connected to the exhaust pipe connecting port 7 of the joint body 3, but any number of pipes may be connected as long as it is two or more. Although one joint pipe 4 is connected to the joint pipe connection port 10 of the joint body 3, any number of joint pipes may be connected.

(C) In the above embodiment, the forming material 6 is expanded in two steps of the temporary expanding step and the main expanding step. However, the pushing speed of the cores 15 and 18 into the forming material 6 is slowed down to perform the main expanding step. The molding material 6 may be expanded only by itself. With this configuration, the first expanding die device 11 can be omitted, and thus the cost of manufacturing equipment can be reduced. Further, instead of expanding the forming material 6 in two steps of the temporary expanding step and the main expanding step, a temporary expanding step may be added between both steps. That is, three or more cores having different diameters may be used to expand the forming material 6 in three or more steps.

(D) The drive source for closing the mold apparatuses 11 and 12 in the temporary expanding step and the main expanding step is not limited to a hydraulic system, a pneumatic system or a mechanical system. Especially if a hydraulic system is adopted, each core 15,
Since the speed at which the 18 is moved toward and away from the respective dies 14 and 17 can be slowed, it is possible to further prevent the molding material 6 from being cracked or wrinkled. Moreover, the number of times of approaching / separating the cores 15 and 18 with respect to the dies 14 and 17 can be set to once.

Next, technical ideas other than the claims that can be understood from the above embodiment will be described together with their effects. (A) The method for manufacturing a joint according to claim 3 or 4, wherein in the expanding step, the molding material is expanded by pressing a cored bar having the same diameter at least twice. With this configuration, it is possible to prevent the expanded molding material from causing springback.

[0040]

According to the invention described in claim 1, it is possible to prevent exhaust gas from the engine from leaking from the joint body. In addition, the appearance can be improved.

According to the second aspect of the present invention, since the number of steps required for manufacturing is reduced, the manufacturing cost can be reduced. According to the invention described in claim 3, in addition to the effect of the invention described in claim 2, since the molding material can be spread evenly, the processing accuracy can be increased and an elaborate joint body can be manufactured. .

According to the invention of claim 4, claim 2
Alternatively, in addition to the effect of the third aspect of the present invention, it is possible to prevent the molding material from wrinkling and cracking even when the moving speed of the cored bar is high.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a usage state of a joint body showing an embodiment of the present invention.

FIG. 2 is likewise a perspective view of the joint body.

FIG. 3 is likewise a sectional view of the joint body.

4 (a) and 4 (b) are sectional views of the mold apparatus showing a temporary expanding step.

5 (a) and 5 (b) are sectional views of the mold device showing the main expanding step.

FIG. 6A is a cross-sectional view of the mold device showing the pressing step.

FIG. 7 is a perspective view of a joint body showing a conventional technique.

[Explanation of symbols]

Exhaust pipe (connection pipe) 2, joint pipe (connection pipe) 4, molding material 6, upper opening 6a, exhaust pipe connection port (first connection port) 7, joint pipe connection port (second connection port) 10 , The first core 1
5, second mandrel 18, joint body 30, axis C.

Claims (4)

[Claims] 1. A first and a second connection port for connecting a connection pipe to the joint body are provided at both ends of the joint body,
A joint in which a plurality of connection pipes are connected to at least one of the connection ports, wherein the joint body is molded from a single tubular molding material. 2. A step of expanding the opening at least on one end side of the tubular cylindrical molding material around the axis of the molding material, and the opening of the molding material expanded in the expanding step along the radial direction thereof. And a method of manufacturing a joint, which comprises a pressing step of pressing. 3. The opening of the molding material is expanded by pushing a mandrel movable along the axial direction of the molding material into the opening of the molding material in the expanding step. 2. The method for manufacturing the joint according to 2. 4. In the expanding step, at least two cores having different diameters are pushed into the opening of the forming material in order from the core having the smaller diameter, whereby the opening of the forming material is formed. The method for manufacturing a joint according to claim 3, wherein the joint is gradually expanded.