JP2010155275A - Weld joint and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weld joint comprising a double exhaust pipe and a flange, and capable of preventing any fusion of an end face of an inner pipe, and a method for manufacturing the same. <P>SOLUTION: In the weld joint comprising a double exhaust pipe 1 consisting of an inner pipe 2 and an outer pipe 3, and a plate-like flange 4, an end face 2a of the inner pipe 2 is arranged on the inner side of the direction of a pipe axis 1a from an end face 3a of the outer pipe 3, and an end 2b of the inner pipe 2 and an end 3b of the outer pipe 3 are welded to each other at at least one part W1. The end 3b of the outer pipe 3 is fitted to a through-hole 4a of the flange 4, and welded all around to an inner surface of the through-hole 4a. A weld bead W2 formed by the all-around welding is separated from the end face 2a of the inner pipe 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a welded joint composed of an exhaust double pipe and a plate-like flange used in a vehicle, and a manufacturing method thereof.

  In the exhaust system of a vehicle, an exhaust double pipe composed of an outer pipe and an inner pipe is employed in order to suppress the temperature drop of the exhaust gas when starting the internal combustion engine and activate the catalyst at an early stage.

  For example, Patent Document 1 and Patent Document 2 are known as welded joints in which a plate-like flange is welded and fixed to the end portion of the exhaust double pipe. In Patent Document 1, the ends of the superposed inner and outer pipes are welded by spot welding, the end of the outer pipe is fitted into the through hole of the flange, and the end face of the outer pipe and the flange are cornered in the through hole. A structure for welding by arc welding such as meat welding is disclosed. Further, the thickness of the outer tube is set to a dimension that functions as a strength holding member, for example, 1.5 to 2.5 mm, and the thickness of the inner tube is thinner than the outer tube so that the heat capacity can be reduced. .6 to 0.8 mm.

  However, in the welded joint disclosed in Patent Document 1, since the heat capacity of the inner tube is smaller than the heat capacity of the outer tube, when the end surface of the outer tube and the flange are welded, the heat capacity of the outer tube and the flange is adjusted. If the amount of heat input for welding is set, the end face of the inner pipe having a small heat capacity may be melted (blown out).

  On the other hand, in Patent Document 2, the end surface of the outer tube and the end surface of the inner tube are shifted in the tube axis direction, the end surface of the outer tube is fillet welded in the hole of the flange, and the end surface of the inner tube is filleted to the outer tube. Although the structure to weld is disclosed, it is not easy to fillet weld the end face of the thin inner tube with a plate thickness of 0.6 to 0.8 mm, and the end face may be melted.

JP-A-9-151730 JP 2005-180270 A

  In view of the above problems, an object of the present invention is to provide a welded joint that can prevent fusing of the end face of the inner pipe in a welded joint including an exhaust double pipe and a flange, and a method for manufacturing the same.

  In order to solve the above problems, according to the invention of claim 1, in a welded joint comprising an exhaust double pipe composed of an inner pipe and an outer pipe and a plate-like flange, the end face of the inner pipe is placed on the outer face. The inner pipe end and the outer pipe end are welded to at least one place from the pipe end surface in the pipe axial direction, and the outer pipe end is fitted into the through hole of the flange. The inner surface of the through-hole is welded all around, and a weld bead formed by the all-around welding is separated from the end surface of the inner tube.

  According to a second invention, in the first invention, the outer tube is formed by combining two halves, and a notch is formed at the tip of the mating part of the two halves, and the two halves The portion where the mating portion and the peripheral edge of the through hole intersect is welded from the outer surface side of the half body, and the notch and the flange are connected to the inside of the through hole and to the inner side of the through hole. The welding bead formed by welding from the outer surface side of the half body and the welding bead formed in the notch are overlapped with each other.

  According to a third aspect, in the first aspect, the through-hole comprises a small diameter portion, a large diameter portion, and a step portion connecting the small diameter portion and the large diameter portion, and the end surface of the outer tube is disposed inside the small diameter portion. The TIG welding torch is rotated with the electrodes directed to the corners formed on the innermost side of the stepped portion, and the stepped portion is melted so that only the outer tube is entirely within the through hole. Weld around.

  According to invention of Claim 4, it is a manufacturing method of the welded joint which consists of an exhaust double pipe comprised by an inner pipe and an outer pipe, and a plate-shaped flange, Comprising: The edge part of the said inner pipe is made into the said outer pipe | tube. A step of welding at least one end of the inner tube and an end of the outer tube disposed on the inner side in the tube axis direction from the end surface; and fitting the end surface of the outer tube to the through-hole of the flange; The method includes a step of welding all the way around the inner surface of the through-hole, and a weld bead formed by the all-around welding is separated from the end surface of the inner tube.

  According to a fifth aspect, in the fourth aspect, the outer tube is formed by combining two halves, a notch is formed at the tip of the mating portion of the two halves, and the two halves Welding the portion where the mating portion and the peripheral edge of the through-hole intersect from the outer surface side of the half body, the notch and the flange, inside the through-hole, and of the through-hole A welding bead formed by welding from the outer surface side of the half body and a weld bead formed in the notch are overlapped with each other.

  According to a sixth aspect, in the fourth aspect, the through hole comprises a small diameter portion, a large diameter portion, and a step portion connecting the small diameter portion and the large diameter portion, and the end surface of the outer tube is formed on the small diameter portion. The TIG welding torch is rotated with the electrode directed toward the corner formed on the innermost side of the stepped portion, the stepped portion is melted, and only the outer tube is placed in the through hole. Weld all around.

  According to the present invention, in a welded joint including an exhaust double pipe and a flange, it is possible to reliably prevent the end face of the inner pipe having a thin plate thickness from being melted.

  The best mode for carrying out the present invention will be described with reference to FIGS.

  1 to 3 show a welded joint and a manufacturing method thereof according to the first embodiment of the present invention. FIG. 1 is a cross-sectional view of a welded joint, FIG. 2 is a cross-sectional view of an exhaust double pipe 1, and FIG. 3 shows an end 3 b of an outer pipe 3 of the exhaust double pipe 1 in a through hole 4 a of a flange 4. It is sectional drawing which shows the state before fitting and all-around welding. In addition, each figure shows the cross section of the left half from the pipe shaft 1a, and does not show the right half.

  As shown in FIG. 2, the exhaust double pipe 1 is composed of a metal inner pipe 2 and an outer pipe 3, and the outer pipe 3 is externally provided with a gap G on the inner pipe 2. The end 3b of the outer tube 3 is reduced in diameter, and the end 2b of the inner tube 2 is fitted into the end 3b. In addition, the end surface 2a of the inner tube 2 is longer than the end surface 3a of the outer tube 3 on the inner side in the tube axis 1a direction (the lower side in the figure), that is, on the side opposite to the side where the flange 4 is joined to the outer tube 3. The position is shifted by L, for example, 5 mm. The length L is appropriately set according to the formation amount of the weld bead W2 so that the weld bead W2 described later is separated from the end surface 2a of the inner tube 2. In this state, the end 2b and the end 3b are welded at least at one place on the circumference of the pipe by spot welding (spot welding) W1.

  On the other hand, the metal flange 4 is a plate-like body having a thickness larger than that of the outer tube 3, for example, about 10 mm, and a through hole 4 a for fitting the end 3 b of the outer tube 3 is formed at the center. ing. Further, the flange 4 has a plurality of bolt insertion holes 4b for fastening to exhaust system parts such as an exhaust port of an internal combustion engine (not shown), a flanged pipe, and an exhaust gas purification device around the through hole 4a. Drilled at intervals.

  Then, as shown in FIG. 3, the end 3b of the outer tube 3 is fitted into the through hole 4a of the flange 4 so that the electrode 5a of the TIG welding torch 5 is directed to the end surface 3a and rotates around the tube axis 1a. When the entire inner surface of the through hole 4a is welded, as shown in FIG. 1, a weld bead W2 is formed, the outer pipe 3 and the through hole 4a are welded, and a welded joint comprising the exhaust double pipe 1 and the flange 4 is formed. can get. At this time, as described above, the end surface 2a of the inner tube 2 is arranged with a position shifted by a length L from the end surface 3a of the outer tube 3, so that the weld bead W2 is connected to the end surface of the inner tube 2. 2a.

  Therefore, the end surface 2b of the inner pipe 2 is not welded, and the fusing of the end surface of the inner pipe having a small plate thickness can be reliably prevented.

  FIG. 4 shows a welded joint and a manufacturing method thereof according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same aspect part as 1st Embodiment, and the description is abbreviate | omitted.

  The outer pipe 13 of the exhaust double pipe 11 is configured by joining two halves 13a and 13b formed by press-molding a metal plate in the middle, and welding the mating portion 13c over the entire length. A V-shaped cutout 13d is formed at the tip of the mating portion 13c. Note that the cutout portion 13d may have a shape that expands toward the tip, and may be formed in a U shape or an arc shape, for example.

  And the site | part P where the matching part 13c and the peripheral part 4c of the through-hole 4a of the flange 4 cross is spot-welded from the outer surface side of the half bodies 13a and 13b with the welding torch 5, and the weld bead W3 is formed.

  Next, when the electrode 5a of the TIG welding torch 5 is directed to the end face 13e of the outer tube 13 and rotated around the tube axis 11a, the end of the outer tube 13 is welded all around in the through hole 4a. W2 is formed. This all-around welding is performed on a single plane of the end face 13e without welding along the shape of the notch 13d. The weld bead W2 is separated from the end surface 2a of the inner pipe 2.

  Next, the notch 13d and the flange 4 are welded inside the through hole 4a and from the inside of the through hole 4a, so that a weld bead W4 is formed. The weld bead W4 is separated from the end surface 2a of the inner pipe 2.

  As a result, the weld bead W4 formed in the notch is melted in the plate thickness direction (outer surface direction) of the halves 13a and 13b, so that the already formed weld bead W3 is melted and the weld beads W3 and W4 overlap. Integrate.

  According to the present embodiment, the same effects as those of the first embodiment can be obtained, and when the outer tube is formed by combining the two halves in the middle state, the mating portion and the flange of the halves are surely secured. It is possible to prevent gas leakage from the joint portion between the outer tube and the flange.

  5 and 6 show a welded joint and a method for manufacturing the same according to a third embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same aspect part as 1st Embodiment, and the description is abbreviate | omitted.

  The through hole of the flange 14 includes a small diameter portion 14a, a large diameter portion 14b, and a step portion 14c that connects the small diameter portion 14a and the large diameter portion 14b. The upper surface of the stepped portion 14c is planar, and has a corner portion 14d on the innermost side of the stepped portion 14c.

  Then, the end surface 3a of the outer tube 3 is disposed in the small diameter portion 14a while being shifted by X amount in the direction of the shaft 1a with respect to the corner 3d, and the outer tube 3 and the flange 14 are positioned and fixed by a jig (not shown). The amount of X is appropriately set according to the formation amount of a weld bead W2 described later.

  Next, the electrode 5a of the TIG welding torch 5 is directed to the corner portion 14d and the TIG welding torch 5 is rotated around the tube axis 1a, so that the step portion 14c is melted all around by the TIG arc. Then, as shown in FIG. 6, the melted stepped portion 14c flows down by its own weight toward the end surface 3a and the small diameter portion 14a, and then solidifies by natural cooling to become a weld bead W2 so that the end surface 3a and the through-hole are completely formed. Circumferentially welded. It is desirable that the corner portion 14d has a minimum R shape. Further, the weld bead W <b> 2 is separated from the end surface 2 a of the inner tube 2.

  According to the present embodiment, the same effects as those of the first embodiment can be obtained, and the melted part (step part 14c) separated from the end surface 3a is melted and moved to the welding part. The pipe and the flange can be welded with an amount of heat input sufficient to melt, and the thermal distortion of the flange is suppressed, and the welding quality can be sufficiently satisfied.

  FIG. 7 shows a welded joint and a method for manufacturing the same according to the fourth embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same aspect part as 1st Embodiment, and the description is abbreviate | omitted.

  In the exhaust double pipe 21, the end 12 b of the inner pipe 12 is expanded in diameter, and the end 12 b is fitted into the end 23 a of the outer pipe 23 while shifting its position by a length L.

  According to this embodiment, the same effect as the first embodiment can be obtained.

  FIG. 8 shows a welded joint and a manufacturing method thereof according to the fifth embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same aspect part as 1st Embodiment, and the description is abbreviate | omitted.

  The flange 24 is formed by bending a thin metal plate, for example, a metal plate of about 3 mm by press working.

  According to this embodiment, the same effects as those of the first embodiment can be obtained, and the heat capacity of the flange becomes smaller than that of the first embodiment, so that the temperature of the exhaust gas can be further reduced when the internal combustion engine is started. And the catalyst can be activated early.

    As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, Even if there is a change of the range which does not deviate from the meaning of this invention, it is included in this invention. The cross-sectional shape orthogonal to the tube axis 1a of the exhaust double pipe 1 is arbitrary such as a perfect circle, an ellipse, an ellipse, a shape connecting a plurality of different arcs, a polygon, and the like. Further, the weld bead W1 may be formed by plug welding (plug welding). Further, the weld bead W2 may be formed by using any welding means such as MIG and laser in addition to the TIG welding. In the case of TIG welding, welding may be performed while supplying a welding wire (a filler metal). Further, the outer pipe and the peripheral edge of the through hole of the flange may be joined by adding TIG welding or MIG welding from the outside. Further, a heat insulating material may be filled in the gap G between the outer tube and the inner tube to increase the heat retention of the exhaust gas. In the second embodiment, the weld beads W2 and W4 may be formed of a weld bead that is continuous in a single stroke. The second embodiment adopts the welding method previously proposed by the applicant of the present invention in JP-A-2007-132193, and other embodiments described in JP-A-2007-132193 are also included in the present invention. The The third embodiment adopts a method for manufacturing a welded joint previously proposed in Japanese Patent Application No. 2008-117848 by the applicant, and other embodiments described in Japanese Patent Application No. 2008-117848 are also included in the present invention. Is included. Further, the present invention can be applied to any exhaust pipe double pipe welded joint welded to a flange, and can be applied to, for example, an exhaust manifold, an outer cylinder of a catalytic converter, or an outer cylinder of a silencer. it can.

Sectional drawing which shows the welded joint which concerns on the 1st Embodiment of this invention. Sectional drawing which shows the exhaust double pipe which concerns on the 1st Embodiment of this invention Sectional drawing which shows the state before fitting the end part of the outer pipe | tube of the exhaust double pipe shown in FIG. 2 with the through-hole of a flange, and the perimeter welding of the inner surface of a through-hole Sectional drawing which shows the welded joint which concerns on the 2nd Embodiment of this invention, and its manufacture. Sectional drawing which shows the state before fitting the end surface of the outer tube | pipe of the welded joint which concerns on the 3rd Embodiment of this invention to the through-hole of a flange, and welding all around from an inner side. Sectional drawing which shows the welded joint which concerns on the 4th Embodiment of this invention. Sectional drawing which shows the welded joint which concerns on the 5th Embodiment of this invention.

Explanation of symbols

1 exhaust double pipe 1a, 11a tube axis 2,12 inner pipe 2a, 12a end face 2b, 12b end part 3, 13, 23 outer pipe 3a, 13e, 23a end face 3b, 23b end part 4, 14, 24 flange 4a, (14a) Through hole W1 Spot welding W2, W3, W4 Weld beads

Claims (6)

In a welded joint comprising an exhaust double pipe composed of an inner pipe and an outer pipe and a plate-like flange,
The end surface of the inner tube is disposed on the inner side in the tube axis direction with respect to the end surface of the outer tube, the end portion of the inner tube and the end portion of the outer tube are welded at least one place, and the end portion of the outer tube is connected to the flange And a weld bead formed by welding all around the inner surface of the through hole and spaced from the end face of the inner tube. The outer tube is formed by combining two halves, forming a notch at the tip of the mating portion of the two halves,
Welding the portion where the mating portion of the two halves and the peripheral edge of the through hole cross from the outer surface side of the half,
Welding the notch and the flange from the inside of the through hole and from the inside of the through hole;
The weld joint according to claim 1, wherein a weld bead formed by welding from the outer surface side of the half body and a weld bead formed in the notch are overlapped.   The through-hole is composed of a small diameter portion, a large diameter portion, and a step portion connecting the small diameter portion and the large diameter portion, and an end surface of the outer tube is arranged in the middle of the small diameter portion, on the innermost side of the step portion. 2. The TIG welding torch is rotated with an electrode directed at a formed corner, and the stepped portion is melted to weld only the outer tube in the through hole. The weld joint described. A method for manufacturing a welded joint comprising an exhaust double pipe composed of an inner pipe and an outer pipe and a plate-like flange,
Disposing the end portion of the inner tube on the inner side in the tube axial direction from the end surface of the outer tube, and welding the end portion of the inner tube and the end portion of the outer tube;
Including fitting the end face of the outer tube to the through hole of the flange and welding the entire inner surface of the through hole;
A method for manufacturing a welded joint, wherein a weld bead formed by all-around welding is separated from an end face of an inner pipe. The outer tube is formed by combining two halves, forming a notch at the tip of the mating portion of the two halves,
Welding a portion where the mating portion of the two halves and the peripheral edge of the through hole intersect from the outer surface side of the half,
Welding the notch and the flange from the inside of the through hole and from the inside of the through hole;
The method for manufacturing a welded joint according to claim 4, wherein a weld bead formed by welding from the outer surface side of the half body and a weld bead formed in the notch are overlapped.   The through-hole is composed of a small diameter portion, a large diameter portion, and a step portion connecting the small diameter portion and the large diameter portion, and an end surface of the outer tube is arranged in the middle of the small diameter portion, on the innermost side of the step portion. 5. The TIG welding torch is rotated by directing an electrode toward a formed corner portion, the step portion is melted, and only the outer tube is welded all around in the through hole. The manufacturing method of the welding joint of description.

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