JP2009248190A - Manufacturing method of weld joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a weld joint which suppresses burn-through at an end face of a tube and thermal distortion of a flange and which fully satisfies welding quality. <P>SOLUTION: This is a manufacturing method of a weld joint comprising a tube 1 and a planar flange 2. With an end face 1a of a tube 1 arranged midway inside a small diameter part 3a of a through-hole 3 of the flange 2, a corner part 3d is formed in the innermost side of a step part 3c connecting the large diameter part 3b and the small diameter part 3a of the through-hole 3. Then, an electrode 5a is directed to the corner part 3d, rotating a TIG welding torch 5, fusing the step part 3c, and welding the entire circumference of the tube 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a welded joint used for joining a pipe and a flange.

  The exhaust pipes connected to the vehicle internal combustion engine are fastened by welding and fixing plate-like flanges to the ends of the exhaust pipes and fastening the flanges with bolts, nuts, or the like. .

  And as a manufacturing method of the welded joint which welds and fixes a flange to the end part of an exhaust pipe, it is common to form a weld part between the annular step part in a flange, and a pipe end part. For example, in Patent Document 1, as shown in FIG. 6, a stepped portion 102 is formed on the inner peripheral surface of the through-hole of the flange 101, and the stepped portion 102 and the end surface 104 of the pipe 103 are flush with each other. Is rotated along the end face 104 to weld the through hole and the pipe all around. For such welding, MIG welding in which a welding rod (wire) is melted by arc heat is generally used.

  However, when TIG welding is applied to the welded joint manufacturing method disclosed in Patent Document 1, if TIG welding is performed with the electrode 105a of the TIG welding torch 105 directed between the stepped portion 102 and the end surface 104, the thickness of the end surface 104 is increased. Since the thickness is much smaller than the thickness of the flange 101, that is, the heat capacity of the end face 104 is smaller than the heat capacity of the flange 101, there is a possibility that the melted portion 106 may occur on the end face 104. Therefore, as shown in FIG. 7, when the electrode 105a is shifted and directed toward the flange 101 having a large heat capacity (left direction in the figure), the problem of the end face 104 being melted is solved, but the amount of heat input to the flange 101 is increased. Therefore, the flange 101 is distorted by heat, the flatness of the flange fastening surface 107 is deteriorated, and the fastening property (sealing property) between the flanges may be impaired. Moreover, there exists a possibility that the crater 108 may arise in the flange 101, and there exists a possibility that welding quality cannot fully be satisfied.

Japanese Utility Model Publication No. 63-154888

  In view of the above problems, the present invention, when joining the annular stepped portion in the flange and the pipe end by TIG welding, suppresses melting of the end face of the pipe and thermal distortion of the flange and sufficiently satisfies the welding quality. An object of the present invention is to provide a method for manufacturing a welded joint.

  In order to solve the above-mentioned problem, according to the invention of claim 1, a method for manufacturing a welded joint comprising a pipe and a plate-like flange, wherein the end face of the pipe is disposed in the middle of the small diameter portion of the through hole of the flange. In this state, a corner portion is formed on the innermost side of the step portion connecting the large diameter portion and the small diameter portion of the through hole, the electrode is directed to the corner portion, the TIG welding torch is rotated, and the step portion is Melt and weld the tube all around.

  In the second invention, in the first invention, the TIG welding torch is rotated with a filler material interposed between the small diameter portion and the pipe.

  According to the present invention, when joining the annular stepped portion in the flange and the pipe end by TIG welding, it is possible to suppress the melting of the end face of the pipe and the thermal distortion of the flange and to sufficiently satisfy the welding quality. it can.

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

  FIG.1 and FIG.2 shows the manufacturing method of the welded joint which concerns on the 1st Embodiment of this invention, and is the TIG welding example which does not use a filler metal. FIG. 1 is a cross-sectional view showing a state before welding the end face 1a of the tube 1 and the through hole 3 of the flange 2, and represents the left half of the shaft 1b of the tube 1. FIG. FIG. 2 is a cross-sectional view showing a state after the end surface 1a and the through hole 3 are welded. The upper part of the figure is the upper part in the welding position, and the pipe is supported substantially vertically.

  The metal pipe 1 can be any pipe such as an electric resistance steel pipe or a pipe formed by welding two monaca halves. Moreover, the cross-sectional shape orthogonal to the axis | shaft 1b of the pipe | tube 1 is arbitrary, such as a perfect circle, an ellipse, an ellipse, the shape which connected several different circular arcs, and a polygon. In addition, the pipe 1 may be a multiple pipe. In this case, the manufacturing method of the present invention is applied to at least one pipe.

  The metal flange 2 is a plate-like body that is thicker than the tube 1, and a through hole 3 is formed in the center thereof. And the through-hole 3 is comprised from the small diameter part 3a, the large diameter part 3b, and the step part 3c which connects the small diameter part 3a and the large diameter part 3b. The upper surface of the step portion 3c is substantially flat, and has a corner portion 3d on the innermost side of the step portion 3c. Further, a plurality of bolt insertion holes 4 for fastening the flange 2 and a flanged pipe (not shown) and exhaust system parts are formed at intervals in the circumferential direction.

  Then, the end surface 1a of the tube 1 is disposed in the small diameter portion 3a while being shifted by X amount in the direction of the shaft 1b with respect to the corner portion 3d, and the tube 1 and the flange 2 are positioned and fixed by a jig (not shown). The amount of X is appropriately set according to the formation amount of the weld bead 6 described later.

  Next, the electrode 5a of the TIG welding torch 5 is directed to the corner 3d and the TIG welding torch 5 is rotated around the shaft 1b, so that the step 3c is melted all around by the TIG arc. The melted step portion 3c flows down by its own weight toward the end surface 1a and the small diameter portion 3a, and then solidifies by natural cooling to become a weld bead 6 so that the end surface 1a and the through hole 3 are welded all around. It is desirable that the corner portion 3d has a minimum R shape.

  According to the present embodiment, the melted part (step part 3c) separated from the pipe end is melted and moved to the welding part, so that the pipe and the flange can be welded with an amount of heat input sufficient to melt the step part 3c. Further, it is possible to suppress the melting of the end face of the pipe and the thermal distortion of the flange, and to sufficiently satisfy the welding quality.

  FIG. 3 shows a method for manufacturing a welded joint according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the aspect same as 1st Embodiment, and the description is abbreviate | omitted.

  The innermost corner 13d of the step 13c in the flange 12 is chamfered. The shape of the step portion 13c and the corner portion 13d is arbitrary as long as the melt volume necessary for forming the weld bead can be secured.

  According to this embodiment, the same effect as the first embodiment can be obtained. Further, the edge portion 13d can be formed by press work regardless of cutting, and the processing cost of the flange can be reduced.

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

  The innermost corner 23d of the step 23c in the flange 22 has a large chamfered shape. The corner 23d may have a large chamfered shape as long as the melt volume necessary for forming the weld bead can be secured.

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

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

  With the filler material 7 (a brazing material such as nickel, silver or copper) interposed between the small diameter portion 3a of the flange 2 and the outer peripheral surface of the tube 1, the TIG welding torch is rotated around the shaft 1b. At the same time that the step portion 3c is melted by the heat input by the TIG arc, the filler material 7 is also melted. The melted filler material 7 fills the gap between the small diameter portion 3 a and the outer peripheral surface of the tube 1 and welds them together. The filler material may be interposed in at least a part (including the entire circumference) of the through hole 3 in the circumferential direction.

  According to this embodiment, the same effects as those of the first embodiment can be obtained, and the pipe and the flange are welded from both the inside and outside, so that both can be welded more firmly.

  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. You may perform this invention, supplying a welding wire (filler material) to a fusion | melting part. Further, TIG welding or MIG welding may be added to the outside of the pipe before and after the present invention. In addition, the number of through holes in the flange is arbitrary, and the present invention is also applied to a joint structure of a common flange in which a plurality of through holes to which a plurality of branch pipes are connected, such as an exhaust manifold (exhaust manifold), are formed. can do.

Sectional drawing which shows the state before welding in the manufacturing method of the welded joint which concerns on the 1st Embodiment of this invention. Sectional drawing which shows the state after welding in the manufacturing method of the welded joint which concerns on the 1st Embodiment of this invention. Sectional drawing which shows the state before welding in the manufacturing method of the welded joint which concerns on the 2nd Embodiment of this invention. Sectional drawing which shows the state before welding in the manufacturing method of the welded joint which concerns on the 3rd Embodiment of this invention. Sectional drawing which shows the state after welding in the manufacturing method of the welded joint which concerns on the 4th Embodiment of this invention. Sectional drawing which shows the welding state regarding the prior art 1 Sectional drawing which shows the other welding state regarding the prior art 1

Explanation of symbols

1 Pipe 1a End face 1b Shaft 2, 12, 22 Flange 3 Through hole 3a Small diameter part 3b Large diameter part 3c, 13c, 23c Step part 3d, 13d, 23d Corner part 5 TIG welding torch 5a Electrode 6 Welding bead 7 Filling material

Claims (2)

A method for manufacturing a welded joint comprising a pipe and a plate-like flange,
A corner is formed on the innermost side of the step portion connecting the large-diameter portion of the through-hole and the small-diameter portion in a state where the end face of the tube is disposed in the middle of the small-diameter portion of the through-hole of the flange, and an electrode is formed at the corner Rotate the TIG welding torch with
A method for manufacturing a welded joint, comprising melting the stepped portion and welding the entire circumference of the pipe.   The method for manufacturing a welded joint according to claim 1, wherein the TIG welding torch is rotated in a state where a filler metal is interposed between the small diameter portion and the pipe.

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