WO2004055313A1

WO2004055313A1 - Deposited body from galvanized steel sheet, steel door, and method of making deposited body

Info

Publication number: WO2004055313A1
Application number: PCT/JP2002/013223
Authority: WO
Inventors: Toshihiko Tsukayama; Ryoji Tomiyama; Akikuni Uchida
Original assignee: Sanwa Shutter Corporation
Priority date: 2001-06-21
Filing date: 2002-12-18
Publication date: 2004-07-01
Also published as: CN1714220A; JP2003001456A; CN100526592C

Abstract

In making a deposited body from a galvanized steel sheet by laser beams, formation of pits in the deposited area is prevented without using a feeler or the like. In forming parent and child doors (1, 2) by suitably cutting and bending a galvanized steel sheet to provide front and rear steel sheets (3, 4) and welding the latter, the deposited area is formed such that, for example, the sheet surface of one steel sheet is abutted against the sheet end surface of the other steel sheet, in such a manner that the front end surface (corresponding to the plate end surface of the invention) (3d), which is the cut plane of the right-hand side bend (3b) of the front steel sheet (3) is abutted against the front surface (sheet surface) of the horizontal right-hand side end edge of the rear steel sheet (4), whereupon the abutted portion is welded by yag laser.

Description

Description Zinc steel plate welded body, steel door, and welded body welding method Technical Field

The present invention belongs to the technical field of a welded body of a galvanized steel sheet, a steel door, and a welded method of the welded body, which are galvanized on the surface of a thin plate-shaped steel sheet. Background art

In general, it is known to increase strength and durability by using a metal material as a building material. As such a metal material, a galvanized steel sheet with a zinc-plated surface is used. By using the galvanized steel sheet, the anti-corrosion property of the surface of the plate material can be enhanced.

By the way, when constructing, for example, a building fixture for construction using a galvanized steel plate, specifically, a door to be installed in an opening, a pair of front and back steel plates (face plates) cut into appropriate dimensions are appropriately bent, and then By welding the necessary parts, a door with a predetermined door thickness is formed between the front and back steel plates. And, as the means for welding, arc welding is generally used, but since the welding method by arc welding is to melt and join the joint portions of metal materials at a high temperature state, There was inevitably a problem that the plate surface near the joint would be distorted or twisted. Therefore, as shown in Fig. 2 1 and 2 2, the bent parts 4 3 a, 4 3 b, 4 3 c, 4 4 a, 4 4 b, 4 4 c of the pair of front and back steel plates 4 3 and 4 4 The comrades dealt with the above-mentioned problems by spot welding, but there is a problem that the welding strength is reduced by doing so, and between the pair of steel plates 4 3 and 4 4 In addition, there is another problem in that it is necessary to interpose not only a plurality of aggregates 5 arranged at the center of the door but also aggregates (so-called power frames) 5 arranged around the four circumferences of the door. .

On the other hand, welding means using a laser beam have been proposed in recent years. In this laser beam welding, the area around the weld does not become hot and the laser -Because the radiation range of the beam is small, there is an advantage that the spa evening does not scatter and almost no bead is generated, and it is possible to weld between different materials such as steel and stainless steel. It is possible to reduce the distortion and twist caused by welding, reduce the aggregate and reduce the need for hard bones.Furthermore, post-treatment such as polishing work and putty repair work after welding Simplification of the system and so on.

However, when welding the galvanized steel plate as described above by welding with one laser beam, for example, as shown in FIG. 23, a bent piece 4 5 a bent into one galvanized steel plate 45, as shown in FIG. And the bent pieces 4 6 a folded in a folded state with a gap in the surface thickness direction on the side of the other galvanized steel plate 4 6 with respect to the bent pieces 45 a When the comrades are in contact with each other, and the contact surfaces of the bent pieces 4 5 a and 4 6 a are welded, a professional hole is formed in the welding process, and pits (dents) are formed on the welding surface. (Refer to the photograph shown in Fig. 24), and there are problems that the welded part becomes weak and the appearance is damaged. For laser beam welding, low melting point zinc (melting point: approx. 4 20 ° C, boiling point: approx. 9 20 ° C) is converted to high melting point iron (melting point: approx. 1580 ° C). Although it will melt in advance, because the time until the steel melts is instantaneous, the steel has already melted before the zinc vaporizes, and the vaporization of zinc and the melting of the steel It is assumed that bubbles are left on the welding surface because they occur in the simultaneous progress state. In particular, as described above, this phenomenon occurs when zinc is vaporized when welding with a large contact area, such as welding between wide contact surfaces in the contact direction of the welding torch. It is known that this phenomenon occurs remarkably because there is no escape. Therefore, in order to deal with this, a filler with a high melting point, for example, copper wire (melting point: about 1> 10 CTC) is added to the welding surface, and the temperature drop of the molten zinc part is measured in advance. In addition to making the mouth hole difficult, it is possible to eliminate the professional hole by vaporizing zinc while the temperature rises slowly, and it is possible to actually eliminate the pitch. (See the photo shown in Fig. 25). However, adding a filler in this way is expensive. In addition, there is a problem that the workability is inferior and the finish is not beautiful, and there is a problem to be solved by the present invention.

Furthermore, when forming a door using such a galvanized steel sheet, a bent portion is formed on at least three sides of a pair of front and back steel plates, and these bent portions are integrated by welding to form a predetermined portion. It has been proposed to form doors with a door thickness. When mass-producing such steel doors by laser one-beam welding, dimensional errors when cutting steel sheets, errors when forming bent parts Need to be considered. On the other hand, in the welding of the bent parts, in order to ensure the welded part and achieve a beautiful finish, when the laser beam welding is performed with a small contact area of the bent parts, the contact area is small. Because of the small amount, the dimensional error that occurs in the steel plate makes it difficult to make contact over the entire length of the bent parts, and a gap may be formed. In this case, if the steel plate is thick, laser beam welding can be used to fill the gap, but the thinner the steel plate, the more difficult it is to fill the gap and absorption of dimensional errors is reduced. There is also a problem that the rate of occurrence of defective products will increase, and there is also a problem that the present invention intends to solve. Disclosure of the invention

The present invention has been made in view of the above circumstances and has been created for the purpose of solving these problems, and is a welded body formed by welding galvanized steel plates, The plate end surface of the other steel plate is abutted against the plate surface of the other steel plate, and the abutting portion is welded by laser one beam welding.

By doing so, the galvanized steel sheet can be welded using a single laser beam, and a reliable welding without a pitting can be performed.

In this structure, the welded body according to the present invention can be a steel door configured by using a pair of front and back galvanized steel sheets.

Further, in this, the front and back steel plates constituting the steel door of the present invention are used. That is, the side of one steel plate is bent, and the end surface of the other steel plate is abutted against the plate surface of the bent portion and welded.

And this invention comprises the steel door which formed the bending part in the peripheral part of at least three sides of a pair of front and back steel plates, and laser beam welded the bending part which mutually opposes, and had predetermined | prescribed dough thickness. In doing so, the steel door is formed by forming the upper or lower edge of the peripheral edge, or the bent parts of the upper and lower edges into L-shaped L-shaped parts. The door thickness is adjustable and laminated.

And by doing in this way, it can weld in the state which can be adjusted in the door thickness direction, and it can be made not to have a gap in the butt | matching part of the bending parts in a right-and-left edge part, and laser one beam Welding by welding can be performed reliably and firmly, and the occurrence of defective products can be reduced when mass-producing steel doors.

In this structure, the left and right edges of the steel door of the present invention are constructed by welding the abutting portions between the plate surface of the bent portion of one steel plate and the end surface of the bent portion of the other steel plate. In this way, in addition to the adjustment in the door thickness direction, it is possible to adjust in the left-right direction, making the welding more reliable and stronger, and the reliability of the product Can be improved.

Furthermore, in this, the bent portions of the steel plates facing each other according to the present invention are formed such that one is an L-shaped L-shaped portion and the other is a folded-back folded portion, and the plate end surface of the L-shaped portion Can be configured to abut against the plate surface of the folded-back portion so that the door width can be adjusted freely, and the welding can be surely and strengthened to improve the reliability of the product.

Further, in this structure, the bent portion at one edge of the front steel plate of the present invention is formed into an L-shaped portion, the bent portion at the other edge is formed into a folded portion, and the bent portion at one edge of the back steel plate is formed. The bent part at the other edge is formed into an L-shaped part, and the edge of the L-shaped part projects into the plate surface of the folded-up part so that the door width can be adjusted. It can be configured so that it can be applied, and the welding is reliable and strong, and the reliability of the product can be improved. Further, in the present invention, when welding galvanized steel plates, the plate end surface of the other steel plate is abutted against the plate surface of one steel plate, and the abutting portion is welded over the entire length by laser beam welding. It is.

And by doing in this way, a welding part can be made into the firm thing in which a peat is not formed.

Brief Description of Drawings

Fig. 1 is a front view of the door.

FIG. 2 is a cross-sectional view taken along the line XX of FIG.

FIG. 3 is a cross-sectional view taken along line YY of FIG.

FIGS. 4 (A), (B), and (C) are cross-sectional views of the main parts. FIG. 5 is a photograph of a part of the welded portion corresponding to the cross-sectional view of FIG. 4 (A).

FIG. 6 is a photograph of a part of the welded portion corresponding to the cross-sectional view of FIG. 4 (B).

FIG. 7 is a photograph of a part of the welded portion corresponding to the cross-sectional view of FIG. 4 (C).

FIG. 8 is an overall front view of the steel door in the second embodiment. 9 (A) and 9 (B) are the XX sectional view and the YY sectional view of FIG. 8, respectively.

FIG. 10 is a ZZ cross-sectional view of FIG.

FIGS. 11 (A) and (B) are front views of a conventional door and a new door, respectively, illustrating the state of measurement of the distortion of the plate surface in the second embodiment.

FIG. 12 is a table showing measured values of a gap gauge for measuring distortion of a steel door in the second embodiment.

FIG. 13 is a cross-sectional view of a steel door in the third embodiment. FIG. 14 is a front view of the main door in the fourth embodiment.

FIG. 15 is a cross-sectional view of the main door in the fourth embodiment. FIG. 16 is a longitudinal sectional view of the main door and the child door in the fourth embodiment. FIG. 17 is a front view of the child door in the fourth embodiment.

FIG. 18 is a cross-sectional view of the child door in the fourth embodiment.

FIGS. 19 (A), (B), and (C) are cross-sectional views of relevant parts in the fifth, sixth, and seventh embodiments, respectively.

FIGS. 20 (A), (B), (C), and (D) are cross-sectional views illustrating the eighth, ninth, +, and eleventh embodiments, respectively.

Figure 21 is a front view of conventional door D.

FIGS. 22 (A) and (B) are a YY sectional view and an XX sectional view of FIG. 21, respectively.

FIG. 23 is a cross-sectional view of the main part in another conventional example.

FIG. 24 is a photograph of a part of the welded portion corresponding to a cross-sectional view of another conventional example.

FIG. 25 is a photograph of a portion of the welded portion (addition of filler) corresponding to a cross-sectional view of another conventional example. BEST MODE FOR CARRYING OUT THE INVENTION

Next, a first embodiment of the present invention will be described with reference to the drawings in FIGS.

In the drawings, 1 is a main door composed of a steel door attached to an opening of a building, and the main door 1 is provided so as to be able to open and close and swing through a hinge 1 a fixed to the right end surface. It has been. The left side of the main door 1 is provided with a child door 2 composed of a steel door, which is adjacent to the main door 1. The pair of parent door 1 and child door 2 are configured to partition the opening. ing. The child door 2 is provided with a hinge 2a on the left end face, and is set so as to be able to provide a wide opening by swinging open and swinging together with the parent door 1.

The main door 1 is finished in the vertical direction finding dimension H, the horizontal direction finding dimension S, and the expected size (door thickness) D. So-called galvanized steel sheet It is used. The front and back plates (hereinafter referred to as front and back steel plates) 3 and 4 are formed into the main door 1 by cutting, bending, and welding as appropriate, but the front steel plate 3 has a top half of the upper end surface on the upper edge. Folding part 3 a for forming the part is bent in an L shape, and the bent part 3 b for forming the right end face on the right edge is bent in the L shape, and the left edge A bent portion 3 c for forming the eye plate is formed in a folded shape so as to cover the right edge of the child door 2 at the portion.

On the other hand, the back steel plate 4 has a bent portion 4 a for forming the back half of the upper end surface at the upper edge portion bent in an L shape, and a bent portion for forming the left end surface at the left edge portion. The part 4 b is bent, but the bent part 4 b is set to be shorter (thinner) than the door thickness D by the expected dimension T of the face plate 3 c. Then, in the integration of the front and back steel plates 3 and 4, one leg piece of the aggregate 5 is fixed to the upper end portion and the lower end portion of the back steel plate 4 in advance, and one of the aggregate 5 is attached to the left and right edges of the back steel plate 4. Secure the leg piece 5a. The aggregate 5 arranged on the left edge has a different shape from other aggregates 5 provided around the periphery of the main door 1, but the reinforcing function is the same. Then, the adhesion of the aggregate 5 to the front and back steel plates 3 and 4 is welding by a laser beam (in this embodiment, a jaggerizer), and the aggregate laser beam is irradiated from the inner surface of one aggregate leg piece 5a. As a result, welding is performed (in the figure, the welding direction is indicated by an arrow W). Further, in this case, the welding of the aggregate 5 to the back steel plate 4 is spot-like welding. Even if it is welded to steel plates 3 and 4, the steel plates 3 and 4 will not be distorted and twisted, and there will be no weld marks on the exposed surfaces (outer surfaces) of the steel plates 3 and 4. However, in the present embodiment, it is sufficient to fix the surface steel plate 3 and the other leg piece 5b of the aggregate 5 with a double-sided tape or the like that does not depend on the laser beam. In this embodiment, Adhering with double-sided tape T.

Subsequently, both steel plates 3 and 4 are brought into contact with each other. The front end surface is a cut surface of the bent portion 3 b on the right side of the front steel plate 3 with respect to the front side surface (plate surface) of the right and left ends of the back steel plate 4. (Corresponding to the plate end face of the present invention) 3d (see Fig. 4 (A)), while the spacer 6 is interposed between the aggregate 5 and the bent portion 3b, Folding The front end surface 3 Θ that is the cut surface of the portion 3 a is abutted against the front end surface 4 c that is the cut surface of the back steel plate 4 and the upper bent portion 4 a, and the bent piece constituting the face plate 3 c The front end surface 4d, which is a cut surface of the bent portion 4b on the left side of the back steel plate 4, is abutted against the back side surface of the steel plate (see FIG. 4 (B)). Each of these abutting portions is sequentially welded over the entire length by an assembler so that the respective portions are integrally fixed. Incidentally, each welded part thus formed is a beautiful welded part without pits, and has an appearance that will not be damaged by design even if it is exposed to the outside (No. 5 (Refer to the photo in Fig. 6) Furthermore, between the front and back steel plates 3 and 4, a metal aggregate 5 is arranged around the four circumferences, and only the core material 7 is arranged at the center. This is because, as a result of welding with a laser, there is little distortion between the steel plates 3 and 4, and the reinforcing strength of the welding strength is sufficiently reinforced by the aggregate 5 around the circumference.

In the figure, 8 is a handle for opening and closing, and 9 is a lock device mounting portion.

On the other hand, the child door 2 is formed as follows. The child door 2 is finished in the upper and lower direction finding dimension H, the left and right direction finding dimension S l, and the expected dimension (door thickness) D. Steel plates 10 and 11 are made of galvanized steel sheets with galvanized surfaces, and are constructed by cutting, bending, and welding a pair of front and back steel plates 10 and 11 as appropriate. . The front steel plate 10 has a bent portion (not shown) for forming a front half of the upper end surface at the upper edge portion, which is bent in an L shape, and a left end surface at the left edge portion. From the left-right direction dimension S 1 to receive the side plate (door-to-door) 3 c on the main door 1 side. Is also formed in a narrow shape, and a bent portion 10 b that bends to the back side is bent in an L shape at the right end portion thereof.

On the other hand, the back steel plate 11 is formed with a bent portion (not shown) for forming the back side half of the upper end surface at the upper edge, and the right edge is bent toward the front side. Then, the first bent portion 1 1 a for forming the right end surface and the second bent portion 1 1 b facing the left side from the edge of the first bent portion 1 1 a are folded back. Song formed The Here, the first bent portion 11a is dimensioned to a length obtained by subtracting the length in the front and back direction of the bent portion 10b of the right side edge of the front steel plate 10 from the door thickness dimension D. The plate surface of the second bent portion 11 b is set to face the front end surface 10 c which is a cut surface of the right edge bent portion 10 b.

And, one piece of the aggregate 5 is fixed to the left edge part of the back steel plate 1 1 while the front and back steel plates 10 and 11 are fixed to the upper end and the lower end of the back steel plate 10 in advance. 5a is fixed by using a laser beam in the same manner as the main door 1, but the surface steel plate 10 and the other leg piece 5b of the aggregate 5 are fixed by the double-sided tape T.

Subsequently, both steel plates 10 and 11 are brought into contact with each other. The front end surface, which is a cut surface of the left bent portion 10 0 a of the front steel plate 10, with respect to the front side surface of the left and right ends of the back steel plate 1 1 1 0 c (see Fig. 4 (A)), and the front end surfaces, which are the cut surfaces of the upper bent parts of the front and back steel plates 10 and 11, are also abutted, and facing the face plate 3 c At the part, the front end face 10 c, which is a cut surface of the right bent part 10 b of the front steel plate 10 0, is abutted against the left front face of the second bent part 1 1 b (Fig. 4). (See (C)). And each of these abutting parts is welded over the entire length with a jig laser, so that each part is fixed integrally. In this case, each welded part is a beautiful welded part without pits. It is welded so that it will not be damaged in design even if it is exposed to the outside (see the photographs in Figs. 5 and 6).

In this way, the parent and child doors 1 and 2 have a beautiful finish with no pits in the welded parts, and the upper ends of the doors 1 and 2 are abutted against the end faces of the galvanized steel plates. The abutting surface is welded by applying a torch of a laser laser at a substantially right angle. Therefore, in the upper part, only the plate thickness is in contact and the contact area is small, and the vaporized zinc can escape from the plate surface side opposite to where the torch is applied. It is presumed that it is not formed and can be welded without pits.

In addition, as shown in Figs. 4, 5, 6, and 7, the welding at the left and right sides of each door 1 and 2 has an angle of approximately 90 degrees with respect to the plate surface of the galvanized steel plate. In this case, the torches of the countersink are attached and welded at an angle of approximately 45 degrees to each plate surface. The welded portion is in contact with the thickness of the galvanized steel sheet in the contact direction of the torch, and the contact area is small, and the zinc bubbles are on the opposite side of the contact with the torch. It is presumed that it is possible to escape from the gap, and that beautiful welding can be performed without forming a peat at the welded portion.

In addition, 1 2 is a locking device for locking between the parent and the child doors 1 and 2. In the embodiment of the present invention configured as described above, each of the parent and child doors 1 made of steel is formed by bending front and back steel plates 3, 4, 10 and 1 1 each having a zinc steel plate appropriately cut. In addition to processing, these steel plates 3 and 4, and 10 and 1 1 are joined together and welded. In this case, each welded part is a cut surface with respect to the plate surface in order to reduce the weld area. The plate end surface is abutted, and the abutting portion is welded by a counter-grasser, so that the contact surface in the abutting direction of the welding torch is made smaller than the plate thickness. As a result, the escape of the blowhole generated during welding is secured and pit formation is eliminated, and the welded part can be firmly integrated without using a filler, and the appearance of the welded part is beautiful and excellent in design. Can be a thing. Moreover, there is no need for a bending allowance for welding, unlike the conventional welding of the bent surfaces of the folding parts, which can reduce the weight and cost. The decline can also be measured.

In this way, in the embodiment in which the present invention is implemented, welding is performed on a zinc steel plate by a tag laser, but the steel plates 3 and 4, 10 and 1 1 are connected to each other between the plate surface and the plate surface. Instead of welding and integrating the contact parts, the plate end surface, which is the cut surface of the plate surface, is abutted against the plate surface and welded, and with respect to the abutting direction of the welding torch Since a small contact area corresponding to the plate thickness of the steel plate is welded, even if the steel melts and the zinc vaporizes almost simultaneously, the bubbles are on the back side opposite to the side to which the torch is applied. It is possible to escape from the side, and there is no problem that pits are generated on the welding surface. By the way, when the front and back steel plates are welded using a laser beam, the dimensional error caused by the welding is so small that it is not necessary to consider it. For this reason, when using a means of welding with a gauger, high dimensional accuracy is required at the time of cutting and bending. Therefore, in the case of the main door 1 in the present embodiment, the front end surface 4d of the left bent portion 4b of the back steel plate 4 protrudes from the back surface of the face plate 3c formed to be folded back on the front steel plate 3. As a configuration in which the eye plate 3 c is formed by contact, the dimensional error is absorbed by adjusting the abutting position of the left bent portion 4 b to the eye plate 3 c. Further, in the case of the child door 2, the front end surface 1 that is the cut surface of the front surface steel plate right-hand bent portion 10 0 b is attached to the plate surface of the right-side second bent portion 1 lb that is the portion that receives the face plate 3 c. It is configured to abut against c, and dimensional errors are absorbed by adjusting the abutment position of the right-side bent part 1 O b against the second bent part 1 1 b. The error absorption in the left-right direction in 2 can be achieved. As a result, it is possible to provide a high-quality door while the dimensional accuracy higher than necessary in the left-right direction is not required. Of course, the present invention is not limited to the above-described embodiment. The second embodiment shown in FIGS. 8 to 12 can also be used.

The steel door 13 of the second embodiment is composed of a pair of front and back steel plates 14 and 15 which are metal plates, and the left and right edges and upper edges of each of the steel plates 14 and 15. And a bent portion 14 4 a, 14 b, 14 c, 15 a, 15 b, which constitutes a surface perpendicular to the plate surfaces of the front and back steel plates 2, 3 and becomes the door thickness 1 5 c is bent in an L shape. Then, each of the bent portions 14 a, 14 b, 14 c, 15 a, 15 b, 15 c is brought into contact with each other in abutting manner, and the end surfaces thus brought into contact with each other are laser-beamed. As a result of welding, the prospective surface in the door thickness direction (front-rear direction) is formed by the integrated bent parts 14a, 14b, 14c, 15a, 15b, 15c. Is set to This is a configuration in which the contact state at the upper edge portion of the first embodiment is performed on three sides except the lower edge portion. Even in this case, the contact direction of the welding torch is Therefore, a small contact area corresponding to the thickness of steel plates 14 and 15 is set to be welded. 1 6 is a long aggregate (an aggregate that functions as a central bone) formed by bending a metal plate into a cross-section, and the aggregate 1 6 is composed of front and back steel plates 1 4, 1 A plurality (three in the second embodiment) are arranged in the left-right width direction in a state of extending vertically between the five. Each of these aggregates 16 includes a pair of front and back leg pieces 16a and 16b.

In addition, the lower edge of the steel door 1 3 is provided with an aggregate 16 having a U-shaped cross section for reinforcement between the front and back steel plates 1 4 and 1 5. Is not a reinforcement of the joining of the front and back steel plates 14 and 15 but is a part where a large force is easily applied during use, so it is provided to prevent deformation of the steel plate under the load during use. The purpose of the aggregate 16 to be obtained is the same as that of the aggregate 5 at the lower edge portion provided in the first embodiment. In addition, the reinforcement liner material 17 is welded to each of the attachment portions of the door closer, the hinge (not shown) and the handle 8 by welding with a laser beam.

Here, when welding with a laser beam, the welded part does not reach a high temperature, the radiation range of the laser beam is small, no spatter is scattered, almost no bead is generated, and between different materials, for example, steel It has features such as welding with stainless steel. Thus, in the present embodiment, the steel door 1 is formed by making full use of the above features, and the welded member is distorted and twisted as in the case of arc welding. As a result, there is an advantage that the aggregate can be reduced, the peripheral bones can be omitted, and post-processing such as polishing work and putty repair work after welding can be dispensed with.

Next, the assembly procedure of the steel door 13 will be described. Each of the front and back steel plates 14 and 15 is cut into a predetermined size from a metal plate, and the bent portions 1 4 a, 14 b, and 14 c are formed by bending the left and right edges and the upper edge of the plates. , 15a, 15b, 15c. Subsequently, one leg piece 16 a of the aggregate 16 having a U-shaped cross section is abutted against the back steel plate 15 at an appropriate interval, and a laser beam is applied from the inner surface of the leg piece 16 a. It is set to be integrated by welding. ₍ By the way, the welding of the aggregate 16 to the back steel plate 15 is the same as the first embodiment. However, even in this case, since the aggregate 16 is welded by a laser beam, even if the aggregate 16 is welded to the back steel plate 3 over its entire length, the back steel plate 15 is not distorted or twisted, and no weld marks are left on the exposed surface of the back steel plate 15. This is also possible.

By the way, the aggregate 16 is interposed between the front and back steel plates 14 and 15 to regulate the reinforcement of the steel plates 14 and 15 when the steel dough 13 is used, as well as to restrict distortion and stagnation. When the aggregate 16 is welded by arc welding, distortion and twist associated with the welding occur. For this reason, conventionally, the number of aggregates 16 interposed between the steel plates 14 and 15 is increased to prevent distortion and twisting of the back steel plate 14 at the formation stage. Since material 16 is welded to back steel plate 15 by spot welding with a laser beam, there is almost no effect of the plate surface shape on back steel plate 15, and steel door 13 is used as aggregate 16 In this embodiment, only the three aggregates 16 at the center and the aggregate 16 at the lower edge are arranged, as long as the strength enough to withstand stagnation and stagnation in the process can be provided. Yes.

Subsequently, after attaching double-sided tape T to the other leg piece 16b of the aggregate 16 welded to the back steel plate 15, the front steel plate 14 is attached to each bent portion 14a, 14b, 14c. , 15 a, 15 b, 15 c are mounted in such a manner that the end faces of each other abut against each other. Then, the double-sided tape T adhered to the aggregate 16 is adhered to the front steel plate 14, and the contact portions of the end faces of the respective bent portions 14a, 14b, 14c, 15a, 15b, 15c Laser one-beam welding is performed, but the welding is performed using a jig or the like so that the end faces of each bent portion 14a, 14b, 14c, 15a, 15b, 15c are in close contact with each other. By using the steel plates 14 and 15 with both steel plates sandwiched between them, welding can be performed reliably and accurately. At this time, these end faces are welded over the entire length, but the bent parts 14a, 14b, 14c, 15a, 15b, 15c will be distorted and twisted. There is no.

Thus, in the second embodiment, the bent portions 14a, 14b, 1 The end faces of 4 c, 15 a, 15 b, and 15 c are welded over the entire length, and the connection strength between the end faces is secured, and the circumference excluding the lower edge of the steel door 13 as before. There is no need to provide aggregate (stressed bone) at the bent parts 14a, 14b, 14c, 15a, 15b, 15c.

Next, with respect to the state of distortion and twist of the steel door 13 (hereinafter referred to as a new door 13) formed based on the second embodiment, the conventional steel formed by conventional arc welding is used. Explains the results of a comparison with the door made of D, (the door shown in Fig. 11 (A), Fig. 21 and Fig. 22 and hereinafter referred to as the conventional door D ') . In the conventional door D ′, the aggregate 5 is arranged in the horizontal direction between the front and back steel plates 43, 44, and four doors, one more than the new door 13, are arranged, In addition, aggregate 5 as a strength bone is arranged on the four peripheral edges, and each member is integrated by arc welding.

These new and conventional doors 13 and D 'are distorted and twisted by placing each door 13 and D' on a horizontal base with the steel plate 14 facing upwards. The gap between the reference ruler and the surface steel plate 14 can be analyzed by a numerical value measured with a gap gauge. 1 As shown in Fig. 1, the standard ruler is applied to each part A, B, C, D, E (illustrated by solid lines) facing left and right, and it is formed between the standard ruler and surface steel plate 2. The I, II, III, IV, and V measurement lines (shown in broken lines, I is the part 50mm inside from the right end, II is the upper part of the aggregate (central bone), and III is the central bone. Measure with a gap gauge at the intersection with the middle bone, IV is near the middle bone, V is 50mm inside the left edge) Based on this, the lateral distortion of each door 13, D 'will be examined. The results of the above measurements are shown in the table of Fig. 12. The unit of these numerical values is millimeters (mm).

According to the table of FIG. 12, each door 13 and D ′ has a slight gap at the center in the left-right direction, that is, the center is slightly dented. And the numerical value indicating the degree of the dent is that of the conventional door D, The numbers are large, and most of them are over 1 mm. Furthermore, it can be seen that the range of the gap that exceeds 1 mm is wider in the conventional door D 'than in the new door 1 3, so the new door 1 3 It can be said that there is almost no lateral distortion during the welding process. Furthermore, the aggregate 5 as the core of the conventional door D, is provided one more than the aggregate 16 of the new door 1 3, and consideration is given to reducing distortion and twisting of the front steel plate 14. As a result, the new door 1 3 can reduce the lateral distortion of the surface steel plate 14 even if the number of aggregates 1 6 is reduced. It is proved that welding by laser beam, the third welding method, hardly deforms the shape of the steel sheet.

For each door 13 and D ', the vertical (vertical) plate state and the diagonal plate state are also compared and examined in the same way as the horizontal plate state is examined. However, the results of the examination are approximately the same measured values for the new door 13 and the conventional door D ', and the values are relatively small, resulting in slight distortion and twisting. As a result, it is proved that the new door 13 is an excellent product with almost no distortion or twisting on the plate surface.

From these facts, the steel door 1 of the first embodiment is also welded with a small contact area by a single beam, so that welding is performed in the same manner as in the second embodiment. It is presumed that there is no distortion or deformation based on this.

As described above, the steel door 13 of the second embodiment is formed by welding with a laser beam when the front and back steel plates 14 and 15 are integrated with the aggregate 16. It can be seen that the deformation of the steel plates 14 and 15 can be almost eliminated. As a result, the number of aggregates 16 interposed between the front and back steel plates 14 and 15 can be reduced. In addition, the bent portions formed at the left and right edges and the upper edge 14 a, 14 b, 14 c, 15 a, 15 b, 15 c are in a state where the contact area is small. The abutted part is covered over the entire length by a laser beam. As a result, it is not necessary to reinforce the joints by providing strong ribs at the peripheral edge of the steel door 1 3, so the so-called strong ribs can be omitted, reducing the number of parts and reducing weight. It can also simplify the production work.

Moreover, also in the copper door 13 of the second embodiment, the welded portion of the peripheral portion has a small contact area corresponding to the plate thickness of the steel plates 14 and 15, so the welded portion No pits are formed, and the finish can be made beautiful, and the cost can be reduced by not requiring a filler.

Next, a third embodiment shown in FIG. 13 will be described. The steel door 18 according to the present embodiment is configured to be used independently as with the steel door 13 according to the second embodiment. In this case, the aggregate 5 is provided at a predetermined interval in the left-right direction, and the aggregate 5 is also arranged on the peripheral portion of the steel door 18. Incidentally, aggregate 5 is integrated with spot steel plate 20 but with spot laser beam welding, and with steel plate 19 with double-sided tape T. ,

In this, the front and back steel plates 19 and 20 are integrated with the same configuration as the first embodiment with respect to the upper and lower edges, and the left edge of the front steel plate 19 with respect to the left edge. The abutting portion between the front end surface 19 b of the L-shaped bent portion 19 a and the left plate surface of the back steel plate 20 is integrated as a welded portion, and further, the right side As for the edge, a contact portion between the front end surface 20 a of the L-shaped bent portion 20 a formed on the right edge of the back steel plate 20 and the left plate surface of the front steel plate 19 is formed. It is configured by integrating as a welding part. Even in this case, by welding over the entire length by the laser beam, the integration of the peripheral portion can be ensured and distortion-free, and as in the first and second embodiments. By welding a portion having a small contact area, it is possible to carry out welding with no pitting and excellent design.

Next, the fourth embodiment shown in FIGS. 14 to 18 will be described. <The door of this embodiment is a double-opened (open / close swingable) left and right (parent, child) pair. Among these, of the pair of front and back (front and rear) that constitute the main door 2 1 The steel plates 2 2 and 2 3 are each composed of a rectangular metal plate (steel plate), and bent portions are formed on the left and right edges and the upper edges of the front and back steel plates 2 2 and 2 3 respectively. The opposing members of these bent parts are configured as described later, and by welding (welding (integrating)) each with a laser beam, the front and back steel plates 2 2, 2 3 and In the same way as in the above embodiments, the main door 21 is formed with a door thickness (probable surface) formed by the bent portion.

Between the front and back steel plates 2 2 and 2 3, a plurality of aggregates 5 arranged in parallel with a predetermined interval in the left-right direction and an aggregate at the lower edge portion are respectively arranged. The pair of front and rear leg pieces 5 a and 5 b and the front and back steel plates 2 2 and 2 3 are integrated by a double-sided tape T. Incidentally, the means for fixing the aggregate 5 to the front and back steel plates 2 2 and 2 3 is as described above. The back steel plate 2 3 and one leg piece 5 a are welded by a laser beam, and the front steel plate 2 2 and The other leg piece 5b can be a double-sided tape T.

In addition, the main door 21 has a handle 8 on one side edge, and a hinge 2 provided at a plurality of locations in the vertical direction for connection to the housing on the other side edge (edge on the suspension side). 1 c, necessary parts such as door closer (not shown) are attached. Next, the integration of the front and back steel plates 2 2 and 2 3 at the left edge of the main door 21 will be described. The bent portion at the left edge of the front steel plate 22 is a folded piece that is folded back in a state where the tip faces the right edge and is in contact with the back surface of the front steel plate 22. (Folded portion) 2 2 a is formed. On the other hand, at the left edge of the back steel plate 2 3, the tip is formed into a substantially L-shaped bent piece (L-shaped portion) 2 3 a that is bent so that the tip faces the front steel plate 2 2 side. . Then, the plate end surface which is the front end surface of the back surface side bent piece 2 3 a is abutted against the plate surface (back surface) of the front surface side bent piece 2 2 a, and the inclination is approximately 45 degrees with respect to the abutting portion Integration is achieved by laser-beam welding using a torch (not shown) that faces the direction.

Incidentally, the door thickness of the main door 21 on the left edge side is set based on the length dimension of the back side bent piece 2 3 a. At this time, the plate end surface of the back-side bent piece 2 3 a is positioned on the inner side of the folded end (left edge) of the front-side bent piece 2 2 a. As a result, the folded portion 2 2 a has a folded-back portion side formed in a door-contact portion (eye plate) 2 1 b that protrudes toward the child door 2 4 side.

On the other hand, the bent portion formed on the right edge of the front steel plate 22 is folded in a folded state with the tip facing the left edge and a predetermined gap between the front steel plate 22 and the front steel plate 22. It is bent (formed on the folded part) and includes a first bent piece 2 2 b that faces the back steel plate 2 3 side and constitutes the door thickness, and a second bent piece 2 2 c that faces the left edge side Configured. The bent part formed on the right edge of the back steel plate 2 3 is a bent piece (L-shaped part) 2 3 bent in a substantially L shape with the tip facing the front steel plate 2 2 side. Formed in part b. Then, the plate end surface which is the front end surface of the back surface side bent piece 2 3 b is abutted against the plate surface (back surface) of the second bent piece 2 2 c of the front surface side bent portion, and against the abutting portion, It is integrated by laser beam welding using a torch (not shown) that faces an inclination direction of approximately 45 degrees. The door thickness of the main door 21 on the right edge side is the back side bent piece. It is set based on the length dimension between 2 3 b and the front side first bent piece 2 2 b.

Furthermore, the bent part formed on the upper edge of the front steel plate 2 2 is a bent piece (L-shaped part) that is bent in a substantially L shape with the tip facing the back steel plate 2 3 side. On the other hand, the bent part formed at the upper edge of the back steel plate 2 3 is a bent piece (L-shaped) with the tip facing the front steel plate 2 2 side. Part) 2 3 c is formed. The two bent pieces 2 2 d and 2 3 c are in a state where the plate surfaces are stacked, that is, in the present embodiment, the lower plate surface of the front side bent piece 2 2 d and the back surface Use a torch (not shown) that is placed in a state where it is in contact with the upper plate surface of the side bent pieces 2 3 c and that faces the direction perpendicular to the two plate surfaces. Are integrated by laser one beam welding, and the door thickness of the main door 21 on the right edge side is based on the front side first bent piece 2 2 d and the back side bent piece 2 3 c. Is set.

Incidentally, in this case, there is no consideration for the escape of the professional hole in the welding, but the upper edge of the door is generally arranged in a blindfold, and if the function as an integral part is sufficient The inferiority in design is not necessary to consider so much and it can be said that there is no problem of pits. The lower edges of the front and back steel plates 2 2 and 2 3 remain in a cut state. In the meantime, as described above, the aggregate 5 is integrated with the double-sided tape 6, and the It is a gap between the leg pieces 5a and 5b of the aggregate 5, and the door thickness at the lower edge is set based on the length dimension of the bottom piece 5c.

In the process of manufacturing the front and back steel plates 2 2 and 2 3 and the aggregate 5, the dimensional errors in the left and right direction (door width direction) 2 2 Folded pieces with a width in the left-right direction 2 2 a, 2nd bent piece 2 2 c against the plate surface 2 3 Left and right bent pieces 2 3 a, 2 3 b It is set so that it can be absorbed by adjusting the position. In addition, the dimensional error in the front-rear direction (door thickness direction) is set so that it can be absorbed by adjusting the overlapping amount of the bent pieces 2 2 d and 2 3 c on the upper edges of the front and back steel plates 2 2 and 2 3 Has been. Thus, for example, even if there is a dimensional error between the bent portions at the left and right edge portions, the amount of overlap with the bent pieces 2 2 d and 2 3 c at the upper edge portion should be adjusted. In addition, the gap is not formed in the butt portion between the bent portions of the left and right edges as well as the upper edge. Note that the error in the upward and downward direction (door height direction) is' cut off at the lower edge, so there is no problem in assembly and no adjustment mechanism is provided.

On the other hand, the child door 2 4 is configured by using a pair of front and back steel plates (steel plates) 2 5 and 2 6 made of metal plates, and the front and back steel plates 2 5 constituting the child door 2 4 The bent portions formed at the left and right edge portions of 26 are constructed as follows.

In other words, the left and right bent portions of the front and back steel plates 2 5 and 2 6 constituting the child door 2 4 are the left bent portion of the front steel plate 25 and the front end faces the right edge side. Folded in a folded shape with a predetermined gap between the steel plate 25 and the first bent piece 2 5a facing the back steel plate 26 and forming the door thickness. The second bent piece 2 5 b facing toward the right side, and the right bent portion is formed into a substantially L-shaped bent piece 2 5 c that bends toward the back steel plate 26. ing. Also, The left bent portion of the back steel plate 26 is composed of a substantially L-shaped bent piece 2 6a that bends toward the front steel plate 25. The right bent portion has a tip at the left edge. 1st bent piece 2 6 which is bent in a folded shape with a predetermined gap between it and the back steel plate 26, and facing the front steel plate 2 5 side. b and a second bent piece 2 5 c facing the right edge side. The upper and lower edges of the front and back steel plates 2 5 and 2 6 are the same as the main door 2 1, and the upper bent portion is formed into L-shaped bent pieces 2 5 d and 2 6 d. The lower edge is cut open.

And the front and back steel plates 25, 26 are a double-sided tape consisting of a plurality of aggregates 5 arranged in the vertical direction between them and an aggregate 5 arranged in the lower side in the left-right direction. The left and right edges and the upper edge face each other, and the front side second bent piece 25 b and the back side bent pieces 26 a Between the end surface, the back side second bent piece 2 6 c at the right edge and between the plate surface of the front side bent piece 2 5 c and the plate end surface of the front side bent piece 2 5 d, 2 The child doors 24 are formed by integrating the 6 d plate surfaces together by welding with a laser beam in the same manner as the parent door 21. At this time, the error in the left-right direction (door width direction) is the L-shaped folding with respect to the plate surfaces of the second folded pieces 2 5 b, 2 6 c with the width in the left-right direction of the front and back steel plates 25, 26. It is absorbed by adjusting the abutment position of the plate end face of the bent pieces 2 5 c, 2 6 a, and the error in the front-rear direction (door thickness direction) is the folding of the upper edge of the front and back steel plates 25, 26 It is set so that it can be absorbed by adjusting the overlapping amount of the curved pieces 2 5 d and 2 6 d. Note that the error in the vertical direction (door height direction) is the same as the main door 24, because the lower end edge is in a state of being cut off, and there is no problem in assembly.

In the child door 2 4, the integrated part with the back steel plate 26 at the right edge of the front steel plate 25 is stepped with respect to the front steel plate 25. When the child door 24 is closed, the stepped portion 2 4 a is set to face the door contact portion 21 b of the parent door 21.

In the fourth embodiment configured as described above, the main door 2 1 and the child door 2 4 Means that bent parts are formed on the left and right edges and upper edges of the front and back steel plates 2 2, 2 3, 2 5 and 26, respectively, and these bent parts are integrated by laser beam welding. The main door 2 1 and the child door 2 4 are each configured to have a door thickness.In this case, the main door 2 1 and the child door 2 4 are welded to each other by laser one-beam welding. It is constructed with a high design that eliminates the need for reinforcement such as the provision of aggregates and does not require post-processing of weld marks. Moreover, in this case, the dimensional error in the left-right direction can be absorbed by making the plate end surface of the bent portion abut against the plate surface of the bent portion that is long in the left-right direction. The dimensional error in the door thickness direction can be absorbed by adjusting the amount of overlap between the plate surfaces of the bent part. As a result, even if a dimensional error occurs in the process of cutting and bending each steel plate 2 2, 2 3, 2 5, 2 6 and aggregate 5, the front and back steel plates 2 2 and 2 3, 2 5 and 2 6 can be absorbed at the stage of abutting, and there is a gap in the welded part of both steel plates 2 2 and 2 3 and 2 5 and 2 6 As a result, it is possible to perform laser one-beam welding in a good butt condition, and welding is ensured and strengthened. Therefore, even in the case of mass production of such steel doors, it is possible to produce with reduced occurrence of defective products, which can be expected to reduce costs o

In addition, in this case, since the welded structure capable of adjusting the door thickness is formed at the upper edge portion, the door thickness direction generated between the left and right edge portions of the front and back steel plates 2 2, 2 3 or 2 5, 26, for example, Dimensional errors can be absorbed by adjusting the amount of overlap with the bent pieces 2 2 d, 2 3 c or 25 d, 26 d in the upper edge.

Furthermore, in the embodiment in which the present invention is implemented, in addition to the adjustment in the door thickness direction, the left and right width direction can also be adjusted, and dimensional errors in both directions can be absorbed. 3 or 25, 26 is a good butt in each direction, and laser beam welding can be performed in this good butt, making it possible to reliably mass-produce superior products. The

Further, according to the present invention, the bent portion is an L-shaped portion, and a portion where the L-shaped portion is overlapped in a stacked manner and laser one-beam welding is performed is a steel door as in the fourth embodiment. It is also possible to dispose at the lower edge instead of the upper edge. In this case, the upper edge may be cut off. Furthermore, it is also possible to provide a configuration in which bent portions are provided on the four circumferences of the steel plate, and the bent portions on the four circumferences are welded by laser one beam. In this, both upper and lower edges are formed in an L-shaped portion. Thus, it can be configured to be adjustable in the door thickness direction. Then, the laser beam welding is performed on the laminated portion of the upper and lower edge portions. In any case, the welded portion (integrated portion) to these laminated portions is located on the upper and lower end surfaces. Because it is blindfolded, there is no inferior design.

FIG. 19 shows the fifth to seventh embodiments. In the fifth embodiment shown in FIG. 19 (A), the steel door 2 7 includes front and back steel plates 28, 2 It is configured so that the bent portions 2 8 a and 2 9 a formed on the peripheral edge of 9 are brought into contact with each other in the overlapping manner on the surface in the thickness direction of the door and welded. Unlike the fourth embodiment, the one's bent portion (in the case of this embodiment, the back side) is such that the outer surfaces of the front and back steel plate bent portions 28a and 29a are flush with each other. On the steel plate side) 29 9 a is formed with a stepped portion 29 9 b.

Further, in the steel door 30 shown in FIG. 19 (B), a prospective surface 3 1a which is a surface in the thickness direction of the door is bent at the periphery of the front steel plate 31 and the prospective surface 3 1a is formed. The bent piece 3 1 b formed inwardly at the front end of the steel plate and the folded piece 3 2 a formed on the peripheral edge of the back steel plate 3 2 are brought into contact with each other in a superposed manner on the back surface side, It is configured to weld. In this case, the folded portion 3 2 c has an R-shaped folded portion, so that the contact area between the folded piece 3 1 b and the folded piece 3 2 c is reduced, and laser beam welding is performed. The blowhole escape is ensured.

Further, the steel door 33 shown in FIG. 19 (C) is a bent piece 3 formed at the peripheral edge of the back steel plate 34 at the one end edge of the prospective surface portion 35 that becomes the door thickness direction surface. 5 a Are welded from the direction orthogonal to the abutting portion, and the peripheral edge of the surface steel plate 3 6 on the bent piece 3 5 a formed at the other end edge portion of the prospective surface portion 35 The parts are brought into contact with each other in a superposed manner, and are welded from the orthogonal direction to the contact part.

In any of the configurations described above, welding with a laser beam over the entire length of the contact portion increases the integrated strength, and the omission or reduction of the aggregate can be achieved. .

Furthermore, it may be as shown in FIG.

That is, in the eighth embodiment shown in FIG. 20 (A), an L-shaped bent piece 3 7 a is formed on the back steel plate 37 side, the first on the front steel plate 38 side, A folded portion with a second bent piece 3 8 a, 3 8 b is formed, and a plate of the second bent piece 3 8 b is formed on the plate surface of the L-shaped bent piece 3 7 a. The end face is abutted and laser beam welding is configured. In this case, as in the case of welding the left and right edge portions of the first embodiment, a laser is applied by applying a torch from an arrow direction inclined approximately 45 degrees with respect to the abutting direction of the plate end surface with respect to the plate surface. One-beam welding is used, and this shape has the advantage that it can be easily positioned by the sensor during welding, enables automatic welding, and can be adjusted in the thickness direction of the door.

Further, in the ninth embodiment shown in FIG. 20 (B), the first, second, and third bent pieces 3 9a, 3 so as to be substantially U-shaped on the surface steel plate 39 side. 9 b and 3 9 c are formed, L-shaped bent piece 40 0 a is formed on the back steel plate 40 side, and the plate end surface of the third bent piece 3 9 c is It is configured to abut against the plate surface of the steel plate 40 and to apply a torch from the direction of the arrow inclined approximately 45 degrees to the abutting portion to perform laser beam welding. This shape also has the advantage that positioning by the sensor is easy and automatic welding is possible, and that adjustment in the thickness direction of the door is possible.

Further, the welded form of the bent portion in the tenth and eleventh embodiments shown in FIGS. 20 (C) and (D) is the bent at the upper edge of the fourth embodiment. The L-shaped bent pieces 4 1 a of the front and back steel plates 4 1, 4 2, 4 2 a It is a structure that can be adjusted in the door thickness direction by welding each other in a laminated form. In this case, as indicated by the arrow in Fig. 20 (C), The torch is tilted approximately 45 degrees to the plate end surface and welded with the torch hitting, and as shown by the arrows in Fig. 20 (D), the torch is orthogonal to the two plate surfaces. In the case of automatic welding, it is difficult to sense the welding position in the case of Fig. 20 (C), so welding is performed as shown in Fig. 20 (D). Can be said to be more effective. In this way, when welding in the orthogonal direction to the two plate surfaces, it is necessary to appropriately adjust the output of the laser beam. Industrial applicability

INDUSTRIAL APPLICABILITY The present invention can be widely applied to a welded galvanized steel sheet that has been galvanized on a thin steel sheet surface, a steel door, and a welding method for the welded body. This is useful when you want to reduce the incidence of defective products when mass-producing steel doors that are one of the welds.

Claims

The scope of the claims

1. A welded body constituted by welding galvanized steel plates, wherein the welded body is abutted against the plate surface of one steel plate, the plate end surface of the other steel plate, and the abutting site is laser beam welding A welded body of galvanized steel that is welded by

2. The welded body of galvanized steel sheet according to claim 1, wherein the welded body is a steel door formed by using a pair of front and back galvanized steel sheets.

3. In claim 2, among the front and back steel plates constituting the steel door, the side portion of one steel plate is bent, and the plate end surface of the other steel plate is abutted against the plate surface of the bent portion and welded. Welded steel sheet.

4. When forming a steel door having a predetermined door thickness by forming a bent portion at the peripheral edge of at least three sides of a pair of front and back steel plates and laser-beam welding the bent portions facing each other. The door made of the upper edge or lower edge of the peripheral edge, or the bent parts of the upper and lower edges are formed into L-shaped L-shaped parts, and these L-shaped parts are adjusted for door thickness. Steel doors that are freely laminated.

5. The left and right edges of the steel door according to claim 4 are formed by welding the abutting portions between the plate surface of the bent portion of one steel plate and the end surface of the bent portion of the other steel plate. Steel door.

6. In claim 5, the bent portions of the steel plates facing each other are formed such that one is an L-shaped L-shaped portion and the other is a folded-back folded portion, and the plate end surface of the L-shaped portion is folded. Steel door that is configured to abut against the plate surface of the door so that the door width can be adjusted.

7. In claim 5 or 6, the bent portion at one edge of the front steel plate is formed into an L-shaped portion, the bent portion at the other edge is formed into a folded portion, and the bent portion at one edge of the back steel plate is formed. The bent part at the other edge is formed into an L-shaped part, and the edge of the L-shaped part projects into the plate surface of the folded-up part so that the door width can be adjusted. A steel door configured to be applied.

8. When welding the galvanized steel plates, the end surface of the other steel plate is abutted against the surface of one steel plate, and the abutting part is made full length by laser beam welding. Welding method of welded body,