JP2008055448A - Weld joint structure, and lap fillet welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weld joint structure and a lap fillet welding method capable of suppressing an increase of the thickness of a member and enhancing the strength. <P>SOLUTION: The weld joint structure 1 of a first invention comprises a first base material part 2, a second base material part 3 lapped on the first base material part 2, and a weld metal 4 formed on a corner between a surface of the first base material part 2 and an end face of the second base material part 3. The end face of the second base material part 3 is inclined so that the first base material part 2 side is located to the distal side from its opposite side, and a throat a1 of the weld metal 4 is not less than the thickness d2 of the second base material part 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a welded joint structure and a lap fillet welding method.

Conventionally, lap fillet welding is known as one of the methods for welding members together. In this overlap fillet welding, another member (hereinafter referred to as “second member”) is overlapped with a certain member (hereinafter referred to as “first member”), and the corner of the surface of the first member and the end surface of the second member is overlapped. Welding is performed.
Japanese Patent Laid-Open No. 8-25080

  In order to improve the strength of the welded joint formed by lap fillet welding as described above, it is effective to increase the “throat thickness” of the fillet (welded metal). However, to increase the throat thickness, it is necessary to increase the fillet leg length. In order to increase the leg length of the fillet, it is necessary to increase the thickness of the second member, but there is a risk of increasing the material cost and reducing the productivity.

  An object of the present invention is to provide a welded joint structure and a lap fillet welding method capable of suppressing an increase in thickness of a member and improving strength.

  A welded joint structure according to a first aspect of the present invention includes a first base material part, a second base material part overlapped with the first base material part, a corner of the surface of the first base material part and an end surface of the second base material part. And a weld metal formed on the surface. And the end surface of the 2nd base material part inclines so that the 1st base material part side may be located in the back side rather than the opposite side, and the throat thickness of a weld metal is more than the thickness of the 2nd base material part Have a size of

  In this welded joint structure, the end surface of the second base material part is inclined so that the first base material part side is located on the back side with respect to the opposite side of the end face of the second base material part. The throat thickness of the weld metal can be made larger than when perpendicular to the surface of the material part. For this reason, the strength of the weld metal can be improved by making the throat thickness of the weld metal larger than the thickness of the second base material portion while suppressing an increase in the thickness of the second base material portion. Thereby, in this welded joint structure, an increase in the thickness of the member can be suppressed and the strength can be improved. Moreover, it can suppress that a weld metal becomes a weakest cross section by making the throat thickness of a weld metal more than the thickness of a 2nd preform | base_material part. For this reason, in this welded joint structure, variation in strength due to variation in the leg length of the weld metal can be reduced.

  The welded joint structure of the second invention is the welded joint structure of the first invention, wherein the thickness of the first base material part is smaller than the thickness of the second base material part.

  In this welded joint structure, since the thickness of the first base material portion is smaller than the thickness of the second base material portion, the material cost of the first base material portion is reduced. For this reason, in this welded joint structure, the manufacturing cost can be reduced. Moreover, since the thickness of the first base material portion does not affect the throat thickness of the weld metal, there is little risk of reducing the strength of the weld metal.

  A welded joint structure according to a third aspect is the welded joint structure according to the second aspect, wherein the second base material portion is superposed so as to be in contact with the outer surface of the first base material portion. And the weld metal is formed in the corner of the outer surface of a 1st preform | base_material part, and the end surface of a 2nd preform | base_material part.

  In this welded joint structure, cracks are more likely to occur from the outer surface of the first base metal part than the second base metal part or the weld metal. For this reason, even if a crack occurs, the crack is generated on the outer surface of the first base material portion, so that it is easily visible from the outside, and safety can be improved.

  The overlapped fillet welding method of the fourth invention includes a step of overlapping the first member and the second member, and a step of performing fillet welding on the corners of the surface of the first member and the end surface of the second member. And the end surface of the 2nd member inclines so that the 1st member side may be located in the back side rather than the opposite side in the state where the 1st member and the 2nd member were piled up.

  In this overlapped fillet welding method, the end surface of the second member is inclined so that the first member side is located on the back side of the opposite side, so that the end surface of the second member is relative to the surface of the first member. Therefore, it is possible to easily form a weld metal having a large throat thickness as compared with the case of being vertical. Thereby, in this lap fillet welding method, the increase in the thickness of the member can be suppressed and the strength can be improved.

  In the welded joint structure according to the present invention, since the throat thickness of the weld metal can be increased, the throat thickness of the weld metal is reduced to the thickness of the second base material portion while suppressing an increase in the thickness of the second base material portion. It is possible to improve the strength of the weld metal with the above size. Thereby, in this welded joint structure, an increase in the thickness of the member can be suppressed and the strength can be improved.

<Configuration of welded joint structure>
A welded joint structure 1 according to an embodiment of the present invention is shown in FIG. The welded joint structure 1 includes a first base material part 2, a second base material part 3 superimposed on the first base material part 2, a surface of the first base material part 2, and an end surface of the second base material part 3. And a weld metal 4 formed at the corner.

  The second base material part 3 is overlapped so as to be in contact with the surface of the first base material part 2, and the weld metal 4 is a corner between the surface of the first base material part 2 and the end face of the second base material part 3. Is formed. The end surface of the second base material part 3 is inclined so that the first base material part 2 side is located on the back side with respect to the opposite side, and the throat thickness a1 of the weld metal 4 is the second base material part 3. The thickness is greater than or equal to d2.

  Here, the inclination of the end face of the second base material part 3 is set so that the throat thickness a1 of the weld metal 4 is equal to or greater than the thickness d2 of the second base material part 3. For example, when the leg lengths a2 and a3 of the weld metal 4 are equal legs, the angle formed by the end surface of the second base material part 3 and the surface of the first base material part 2 should be 67.4 degrees or less. Is obtained by calculation. The “throat thickness” here means the height (see reference numeral a1 in FIG. 1) of the joint having a triangular cross section determined by the size of the weld metal 4 (see reference numeral a1 in FIG. 1). The shortest distance from the cross-sectional route to the surface may be used as the throat thickness.

  In addition, the thickness d1 of the first base material part 2 is smaller than the thickness d2 of the second base material part 3 and is large enough to cause cracking in preference to the second base material part 3 and the weld metal 4. Is set.

<Contents of lap fillet welding method>
The weld joint structure 1 is formed by the lap fillet welding method shown in FIG. As shown in FIG. 3, this overlap fillet welding method includes a first step S <b> 1 for overlapping the first member 11 and the second member 12, and the surface of the first member 11 and the end surface 13 of the second member 12. A second step S2 and a third step S3 for fillet welding the corners to be configured are provided.

  In the first step S1, the first member 11 and the second member 12 are set. Here, the first member 11 and the second member 12 are overlapped so that the front end portion of the second member 12 overlaps the surface of the first member 11. The distal end portion of the second member 12 is processed so that the end surface 13 thereof is inclined. In the state where the first member 11 and the second member 12 are overlapped, the end surface 13 of the second member 12 is It inclines so that the member 11 side may be located in the back | inner side rather than the opposite side. Here, the angle θ1 of the end surface 13 of the second member 12 is an angle corresponding to the angle of the end surface of the second base material part 3 described above, but due to the penetration during welding, Since it does not completely coincide with the end surface of the second base material part 3, the angle θ1 may be set so as to be the angle of the end surface of the second base material part 3 after welding. For example, the angle θ1 may be set to 70 ° or less.

  In 2nd process S2 and 3rd process S3, as shown in FIG. 4, fillet welding which welds the corner of the surface of the 1st member 11 and the end surface 13 of the 2nd member 12 is performed. Here, the welding torch 14 approaches the first member 11 and the second member 12, and the tip of the welding wire 15 protruding from the tip of the welding torch 14 is the surface of the first member 11 and the end surface 13 of the second member 12. And the welding is started. Then, when the welding torch 14 moves while welding, the weld metal 4 extends over the space between the end surface 13 of the second member 12 and the surface of the first member 11 and the outer portion thereof (see FIG. 1). ) To form the above-described welded joint structure 1. In this fillet welding step, the first fillet welding in the second step S2 and the second fillet welding in the third step S3 are performed.

  First, in the first fillet welding, as shown in FIG. 4A, the tip of the welding wire 15 is close to the route P1 between the first member 11 and the second member 12 along the route P1 (FIG. 4 (in a direction perpendicular to the sheet of FIG. 4), a weld metal (hereinafter referred to as “first layer 16”) is formed in the space near the route P1 between the first member 11 and the second member 12 (hereinafter referred to as “first layer 16”). (Refer FIG.4 (b)). Here, the welding torch 14 is tilted at a predetermined first angle θ2, and moves without weaving.

  When the first fillet welding is completed, the second fillet welding is then performed. In the second fillet welding, as shown in FIG. 4B, the second layer is formed by further welding the outside of the first layer 16 formed by the first fillet welding. At this time, the welding torch 14 moves in parallel to the end surface 13 of the second member 12 along the outside of the first layer 16. The welding torch 14 is inclined at a second angle θ3 larger than the first angle θ2, and moves in a standing state as compared with the case where the first fillet welding is performed. Further, the welding torch 14 moves while weaving at a predetermined frequency and amplitude. The second layer formed by the second fillet welding melts with the first layer 16 and becomes the weld metal 4 together with the first layer 16.

  The overlap fillet welding method is automatically performed by a welding robot, but can also be used in manual welding.

  Moreover, the 1st member 11 and the 2nd member 12 welded by this overlap fillet welding method may be not only a flat plate but a tubular member. For example, as shown in FIG. 5, the lap fillet welding method according to the present invention can be used for joining a circular flange member 17 and a tube material 18. 5A is an external perspective view of a part of the hydraulic cylinder including the flange member 17 and the tube member 18, and shows a state before welding. FIG.5 (b) is sectional drawing of the junction part after welding. Here, the tip of the flange member 17 is overlapped with the outer peripheral surface (outer surface) of the tube material 18, and the weld metal 19 is formed along the corners of the outer peripheral surface of the tube material 18 and the end surface of the flange member 17. ing.

  Further, the welded joint structure and the lap fillet welding method are not limited to the joining of hollow circular pipes, but can also be applied to a case where a hollow circular pipe is overlapped and joined to the outer peripheral surface of a solid cylindrical member. .

<Features>
(1)
In the welded joint structure 1 and the lap fillet welding method of the present invention, the throat thickness a1 of the weld metal 4 is increased by stacking the second member 12 having the inclined end face 13 on the first member 11 and performing fillet weld. Can do. Thereby, the strength can be improved while suppressing an increase in the plate thickness of the second member 12.

  In general, a butt joint structure joined by reverse wave welding is often used as the weld joint structure, but such a structure is excellent in strength, but it is necessary to process the back surface flatly. Therefore, there is a problem that productivity is inferior. Further, in order to increase the thickness of the weld metal and improve the strength of the weld metal, it is necessary to increase the plate thickness of both base materials to be abutted, resulting in an increase in material cost. On the other hand, in the welded joint structure 1 and the lap fillet welding method of the present invention, the plate thickness can be reduced more than the butt joint structure while ensuring the strength of the weld metal, and the material cost can be reduced. Can do. Moreover, the processing required after back wave welding is unnecessary, and the productivity is high.

(2)
In the welded joint structure 1 and the lap fillet welding method of the present invention, the throat thickness a1 can be increased with a small amount of welding compared to the case where the second member 12 having the end surface perpendicular to the first member 11 is welded. . For this reason, productivity can be improved.

(3)
In the welded joint structure 1 and the lap fillet welding method of the present invention, the weakest cross section in the welded joint structure 1 is not the weld metal 4 by making the throat thickness a1 larger than the thickness d2 of the second base material part 3. The first base material part 2 can be positioned. Thereby, since the fatigue strength in the welded joint structure 1 is more easily affected by the first base metal part 2 than the weld metal 4, it is suppressed from being affected by the leg lengths a2 and a3 of the weld metal 4 that are likely to vary. As a result, the variation in strength of the welded joint structure 1 is reduced.

(4)
In this welded joint structure 1, the weakest cross section is located in the first base material part 2, so that cracks are preferentially generated from the first base material part 2 over other parts. For this reason, compared with the case where a crack occurs in the weld metal 4 from the route of the weld metal 4, the occurrence of the crack can be easily found.

  Next, an embodiment of the present invention will be described.

〔conditions〕
In this embodiment, overlap fillet welding is performed using a plate-like first member 11 having a thickness d1 of 6 mm and a plate-like second member 12 having a thickness d2 of 9 mm in FIG. The inclination angle θ1 of the end face 13 of the second member 12 is 60 degrees. Welding is performed by automatic welding by a welding robot, and the welding conditions are set so that the leg lengths a2 and a3 (see FIG. 1) of the weld metal 4 are 9 × 9 mm. Specific welding conditions are as follows.

[Welding conditions for first fillet welding]
Welding current: 275A
Welding voltage: 28V
Moving speed of welding torch 14: 33 cm / min
No weaving Inclination angle of the welding torch 14 (first angle θ2): 30 °
[Welding conditions for second fillet welding]
Welding current: 320A
Welding voltage: 32V
Moving speed of welding torch 14: 35 cm / min
Weaving frequency: 3Hz
Weaving amplitude: 1.5mm
Inclination angle of the welding torch 14 (second angle θ3): 55 °
〔result〕
As a result of lap fillet welding under the above conditions, a welded joint structure 1 in which the throat thickness a1 of the weld metal 4 was 11 mm was obtained.

  In addition, as a result of performing a fatigue test on the obtained welded joint structure 1 by fixing the second base material part 3 and repeatedly applying a load (see arrow F1 in FIG. 6) to the first base material part 2, A crack C1 occurred from the toe part P2 between the first base material part 2 and the weld metal 4.

  INDUSTRIAL APPLICABILITY The present invention has an effect of suppressing an increase in thickness of a member and improving strength, and is useful as a welded joint structure and a lap fillet welding method.

Sectional drawing of the welded joint structure which concerns on this invention. The figure which shows the flow of the overlap fillet welding method which concerns on this invention. The figure which shows the 1st member and 2nd member in a 1st process. The figure which shows the 1st member and 2nd member in a fillet welding, and a welding torch. The figure which shows a part of hydraulic cylinder which can apply the welded joint structure which concerns on this invention. The figure which shows the welded joint structure in Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Welded joint structure 2 1st base material part 3 2nd base material part 4 Weld metal 11 1st member 12 2nd member

Claims (4)

A first base metal part;
A second base material portion superimposed on the first base material portion;
Weld metal formed at the corners of the surface of the first base material part and the end face of the second base material part;
With
The end surface of the second base material part is inclined so that the first base material part side is located on the back side of the opposite side,
The throat thickness of the weld metal has a size equal to or greater than the thickness of the second base material portion.
Welded joint structure. The thickness of the first base material part is smaller than the thickness of the second base material part,
The welded joint structure according to claim 1. The second base material part is overlaid so as to contact the outer surface of the first base material part,
The weld metal is formed at corners of an outer surface of the first base material part and an end surface of the second base material part,
The welded joint structure according to claim 2. Superimposing the first member and the second member;
Fillet welding the corners of the surface of the first member and the end surface of the second member;
With
The end surface of the second member is inclined so that the first member side is located on the back side of the opposite side in the state where the first member and the second member are overlapped,
Lap fillet welding method.

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