JPH1133715A - Method of welding inner corner of t joint and t joint structural member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To weld even the inner corner of thick plate welded structural member rectangular T joint without a generation of defect by a narrow grove welding method. SOLUTION: A weld zone of the inner corner is divided into peripheral ranges centering on the inflection point and the range of the right and left sides, which are handled as an aggregate of linear welding respectively. As to the welding sequence, the periphery of the inflection point is completed to the groove surface portion first to form a weld bead 111, and then right and left weld beads 112 and 113 are formed in the same way. In this method, the groove rear portion and bead surface already formed to be the first ending point of each pass arc form the substrate face of the boat form, and the shielding of shielded gas can be securely held.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a T
The present invention relates to a welding method and a T-joint structure at a joint corner.

[0002]

2. Description of the Related Art There are many cases where a main joint is wound around a rectangular T-joint welding line, such as a pressure vessel designed and manufactured with a welding structure. In this case, inner and outer welding are performed at a corner of a corner. Work always accompanies. FIG. 7 is an external view showing an example of the pressure vessel. The pressure vessel 1 comprises an upper case 2 and a lower case 3. The upper case 2 is formed by multi-layer welding of the entire periphery of the upper flange 4 and the upper plate 6 by a T-joint welded portion 8 having a rectangular welding line. Similarly, the lower case 3 is formed by the lower flange 5 and the lower plate. 7 is formed by multi-layer welding at a T-joint weld. For this T-joint welding, a JIS Z3021 welding symbol 形 -shaped T-joint (Description example-6) is often used. FIG. 8 shows that the multi-layer welding using the T-shaped joint is performed by the upper plate 6.
FIG. 4 shows a cross section taken between the upper flange 4 and the upper flange 4. A cross-section to be welded between the upper plate 6 and the horizontal flange 4 is formed. (About 30 °). Reference numeral 10 denotes a backing material. When both members to be welded here are thick plates, each pass welding 9 (the longitudinal direction is perpendicular to the drawing) is sequentially laminated from the back portion of the backing material 10 to the surface layer portion, and the multilayer Welding 8 is completed.

FIG. 2 shows another shape of a T-joint. It shows a joint cross section in narrow groove welding, in which the groove surface is not sharpened as in the case of the D-type, and a parallel groove having a constant root interval of the section to be welded. For this reason, compared with the above-mentioned R-shaped joint, the cross-sectional area to be welded is extremely small, about 1/3 with respect to the same plate thickness t. The first welding bead 11 can be completed.

[0004]

Generally, in the case of T-joint welding, manual arc welding using a covered arc welding rod or semi-automatic arc welding using a coil material is performed as shown in FIG. Perform multi-layer welding. During the inner circumferential portion of the rectangular welding line in this welding process, in the former manual arc welding, there is no interference of the welding rod at the bending point, so that the direction of the rod movement is suddenly changed, and the continuous welding is performed. Welding is possible. However, it is not efficient as a whole due to manual work. On the other hand, in the latter semi-automatic arc welding, since the tip of the welding torch interferes with the groove surface when constructing the inner peripheral portion, continuous welding of the corner is performed while adjusting the aiming direction of the arc in advance. In other words, the welding may be performed while using the torch advance angle and the receding angle properly, or the arc may be cut off once at the bending point, and the torch angle may be changed to start again. However, a sudden change in the torch angle or a joint of the weld bead tends to cause a shield defect of the encapsulating gas, and easily causes a welding defect.

[0005] The narrow groove welding method described above is a very effective means for reducing the welding cost because its cross-sectional area to be welded is small, but it is the same as semi-automatic arc welding for inner corner welding. The torch interferes with the groove surface, and practical use is considerably difficult. For this reason, this narrow groove welding method is currently applied to outer corner welding at the joints of vertical columns in the building industry, but has not yet been put to practical use in inner corner welding.

SUMMARY OF THE INVENTION It is an object of the present invention to automatically weld the inner periphery of a thick T-joint by using a narrow groove welding method that can reduce welding cost and also to prevent welding defects. Method and welding method at T-joint corner
It is to provide a joint structure.

[0007]

According to the present invention, in the T-joint narrow groove welding, the welding range is first divided into a range starting from a corner point of the corner and a range on both left and right sides thereof. In the middle, multi-layer welding of corners is performed as a set of linear welding without changing the torch angle. Welding first,
After completing the area around the bending point up to the groove surface, it is moved to the left and right sides. At that time, the start and end points of the arc (start point, creator processing point) in any multi-pass welding 5), the lamination method is such that the groove wall surface and the formed bead surface have a boat-shaped lower ground surface.

[0008]

Embodiments of the present invention will be described below. First, the inner corner portion of the rectangular welding line to which the present invention is applied corresponds to the bending point 81 and the welded portion around the bending point 81 in the external view of the pressure vessel in FIG. FIG. 3 shows the range of formation of the weld metal formed by the welding operation according to the method of the present invention in the inside corner of the corner. In the figure, points a, b, c, d, e, f, g, and h are all on the same plane, that is, on the upper surface of the upper flange 4. Points a ', b', c ', d', e ', f', g ', and h' are T
It is on the groove surface of the upper plate 4 adapted to form a joint narrow groove. Here, the line segments cc ′ and ff ′ represent the surface bending line and the back bending line in the weld metal formation range, respectively. In the present invention, this weld metal formation range is divided into three ranges and welded. The first section is centered on the corner bent portion in FIG. 3, and is divided into a surface gg'c'c, a surface cc'h'h, and a surface hh '.
f'f, a portion surrounded by faces ff'g'g, a second section is a section interposed between planes aa'b'b and gg'c'c, and a third section is plane cc'h ' h and the surface dd'e'e. However, points g, c and h are on a straight line, and points g,
c, h, g ', c', h 'are coplanar. In addition to the backing material 12 shown in FIG.
It is assumed that a backing material is provided on f and the surface ff'e'e.

Next, these first to third sections are sequentially welded by a narrow groove welding method. FIG. 4 shows a laminating method of narrow groove welding in the first section. First, a first pass p1 is horizontally welded on the lower surface side in a deep portion of the groove, and a pass p2 is similarly welded on the upper surface side. Then, the first layer is completed. At this time, the backing material 12 is provided at the back of the groove. Next, a second layer is sequentially laminated by a path p2 (lower side, omitted in FIG. 4) and p3 (upper side, omitted in FIG. 4). Path p9, p10
The fifth layer, which is formed at the middle of the groove depth, is formed in such a manner that the welding beads 121 of the first section are formed by multi-pass lamination. The narrow groove welding in each of these passes is all in the horizontal position, the welding direction can be left or right, and both the arc start point and the creator processing point are backing the back of the groove. The contact surface with the material has a boat-like shape of about 45 ° with respect to the welding direction, so that good welding quality can be easily obtained. In addition, it is sufficiently possible to perform automatic lamination by repeating a linear reciprocating operation by a traveling device holding a welding torch in these welding operations. FIG. 5 is an external view of the weld bead 111 in which the welding in the range of the first section has been completed. FIG. In addition, in order to obtain good welding quality, in particular, at each intersection, the intersection between the weld bead and the wall surface of the groove is arced.
Since it is important to orient the welding wire, the welding wire is provided with a bend in advance by a feed mechanism, but a known technique is used for the method and the like, and a description thereof is omitted here. This is the same in the following.

Next, a narrow groove welding lamination method in the weld metal forming range of the second section will be described with reference to FIG. In FIG.
The first section around the bend point has completed the welding bead 111. In the welding of the second section, first, a point a on the lower surface side of the back of the groove is linearly welded in a horizontal ag direction in a horizontal path in the first pass p1.
Next, the point a ′ on the groove upper surface side is welded by the pass p2, and the first layer is laminated. The welding direction can be either left or right. Thereafter, the multi-pass welding of the second layer,..., The fifth layer (passes p9 and p10 in the middle of the groove depth) is continued. Two weld beads 112 are formed. At this time, the arc start point and the crater processing point for each pass become a bead joint at the contact surface with the bead surface of the welded bead 111, and in each case, about 45 °. Since the boat-shaped lower ground is formed, joining work without any defect can be easily performed.

[0011] In the same manner, multi-pass welding is also performed on the weld metal forming range in the third section. Thus, welding bead 113
The completed drawing, ie, the inner corner turning T-joint welded part
FIG. 1 shows a state where each of the parts is divided into two parts, and each part is completed by multi-pass welding using lateral narrow groove welding.

As apparent from the above description, according to the welding method in the T-joint corner of the present invention, (1) in all passes, straight welding is performed without changing the torch angle during welding. An extremely stable arc can be maintained. (2) At the initial end of welding, the base surface to be welded has an ideal boat shape, so that the arc can be easily started and cratered. Extremely high quality welding can be performed because no torch interference occurs with the contact surface. (3) Since each pass of the narrow groove welding is a simple straight line welding and the lamination method has regularity, automatic welding can be easily performed. There is a direct effect. Indirectly, the welding work does not require reversal of heavy structures, etc., and the horizontal narrow groove welding is performed in the same posture, so safe and high-quality welding can be performed, and the economy is rich. A welding lamination method can be realized.

[0013]

According to the present invention, in the welding of a rectangular T-joint of a pressure vessel or the like having a welded structure, in particular, when welding the inner periphery of a corner, the welding range is divided into three parts based on the corner point of the corner. Since the straight narrow groove welding can be performed for each, there is an effect that automation can be performed and narrow groove welding with high welding quality can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a completed example of a narrow inner groove welding inside a corner according to the method of the present invention.

FIG. 2 is a view showing a cross section of a narrow groove welding joint.

FIG. 3 is a divided view of a weld metal forming range which is a feature of the present invention.

FIG. 4 is an explanatory view of a narrow groove welding lamination method in a first section of FIG. 3;

FIG. 5 is an external view of a weld bead in a first section of FIG. 3;

FIG. 6 is an explanatory view of a narrow groove welding lamination method in the second section of FIG. 3;

FIG. 7 is an external view of a pressure vessel.

FIG. 8 is a cross-sectional view of a multi-layer welding.

[Explanation of symbols]

 4, 5 Upper and lower flanges 6, 7 Upper and lower plates 10 Backing material 11 Narrow groove welding bead 12 B Forming weld metal forming area 111 First section welding bead 112 Second section welding bead 113 Section 3 welding bead cc 'Surface bending line ff' Back bending line

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B23K 9/173 B23K 9/173 D (72) Inventor Hisao Kato 603, Kandamachi, Tsuchiura-shi, Ibaraki Pref. (72) Inventor Takao Naruse 603, Kandamachi, Tsuchiura-shi, Ibaraki Prefecture Within Hitachi Tsuchiura Engineering Co., Ltd.

Claims (5)

[Claims] 1. A welding method for a T-joint inner turning corner in a T-joint welded portion between a flange of a thick plate welding structure and a side plate, wherein a welding surface of the side plate is formed as a narrow groove welding surface, The weld metal forming range of the inner corner is divided into three parts, and the divided parts are sequentially subjected to multi-pass welding by a narrow groove welding method.
Welding method at the inner corner of the joint. 2. A first portion including a bent line in a deep portion of the weld metal forming range, the first portion including a bent line in a deep portion of the weld metal forming range, by a surface including a bent line of a surface layer portion of the weld metal forming range; The welding method according to claim 1, wherein the first and second portions are divided into second and third portions extending linearly from the first portion. 3. The multi-pass welding in each of the three divided parts is a straight-line welding from the generation of an arc to the crater treatment in each pass welding, and the torch angle is not changed during welding. Claims 1
Item 3. The welding method at the inner corner of the T-joint according to item 2 or 2. 4. The multi-pass welding of the three divided portions is performed by performing the multi-pass welding of the first portion from the deep portion of the groove surface to the surface layer portion, and then performing the multi-pass welding of the second and third portions. 4. The welding method according to claim 3, wherein the multi-pass welding for each of them is performed sequentially from the deep portion of the groove surface to the surface layer portion. 5. A T-joint structure in which a flange and a side plate are welded and joined by a T-joint, wherein a side plate having a weld surface formed as a narrow groove welding surface and a weld metal forming area of a T-joint inner corner are formed. And a connection part which is sequentially multi-pass welded by a narrow groove welding method.