KR100368768B1 - Mash seam-welding device and method thereof - Google Patents

Abstract

The conveyor system is divided into two-stage and three-stage ball conveyors, and a base frame is applied so that the slides can be moved in parallel to each other, so that the welder body moves the two-stage and three-stage ball conveyors continuously to at least three sheets of different steel sheets. In order to provide a mash seam welding apparatus and method for enabling welding work, to effectively respond to changes in product specifications in one working environment, and to provide flexibility in the working environment and production management,

In mash seam welding device,

A pair consists of two sets of ball conveyors consisting of two rows, each divided into a two-stage ball conveyor and a three-stage ball conveyor with the clamping means, and the first and second articles of the two and three stage ball conveyors Pushing means each configured to push the trailing steel plate to the clamping means is configured,

A mash seam welding device further comprising a left and right moving means at a lower portion of the main body of the welder so as to slide in parallel in the longitudinal direction with respect to the two-stage and three-stage ball conveyors;

Welding method of the mash seam welding apparatus which overlaps the preceding steel plate and the following steel plate on the conveyor apparatus, and fixes them respectively through the clamping means and piezoelectrically welds the overlap section through the upper and lower electrode wheels interlocked with the welder main body. in,

The conveyor apparatus is divided into a two-stage ball conveyor for welding two sheets of steel sheet, and a three-stage ball conveyor for welding three sheets of steel sheet, and a welder body is connected to the two-stage ball conveyor along a longitudinal direction on one side of the conveyor. Mash seam welding, characterized in that the slide can be moved so as to move between the three-stage ball conveyor so that a plurality of steel plates can be welded by the upper and lower electrode wheels through the two-stage welding process and the three-stage welding process. Provide a method.

Description

Mesh seam welding device and its method {MASH SEAM-WELDING DEVICE AND METHOD THEREOF}

The present invention relates to a mash seam welding apparatus and a method thereof, and more particularly, to be able to continuously weld a plurality of sheets of different thicknesses or materials in a single working environment without any additional process, product specifications The present invention relates to a mesh seam welding apparatus and a method for effectively responding to the change of the.

In general, the mash seam welding apparatus is a device for welding a single steel plate by piezoelectric agglomeration through upper and lower electrode wheels by overlapping two sheets of steel sheets having different thicknesses or materials, and as shown in FIG. The preceding clamp 107 and the trailing clamp 109 are respectively configured to support it on the conveyor 105 for supplying the preceding steel sheet 101 and the trailing steel sheet 103, and between the preceding and trailing clamps 107 and 109. In the welder body 111, the upper and lower electrode wheels 115 and 117 connected to the pressure cylinder 113 are configured.

Accordingly, when the wire and trailing steel plates 101 and 103 made of two steel sheets are supplied and overlapped through the conveyor 105, the preceding and trailing clamps 107 and 109 respectively fix them, and at this time, the welding machine main body 111 is advanced. While the pressure cylinder 113 is operated, upper and lower electrode wheels 115 and 117 weld overlapping sections of the preceding and following steel sheets 101 and 103.

As the welder main body 111 moves forward as described above, the pressurizing cylinder 113 is released while the welder main body 111 is reversed again and the upper and lower electrode wheels 115 and 117 are removed from the welded state. This will complete the mash seam welding of the two different steel sheets.

However, according to the mash seam welding apparatus and the welding method as described above, the working environment is fixed to weld two different steel sheets, which is advantageous for mass production of a product made by welding only two steel sheets. In order to weld three or more different steel sheets, an additional process must be added, and in particular, even in the production of multiple products, it is difficult to deal with flexibly in terms of work environment and production management.

Therefore, the present invention was created to solve the above-mentioned problems, an object of the present invention is to divide the conveyor apparatus into a two-stage and three-stage ball conveyor, by applying a base frame to be able to slide in parallel, The welding machine main body can continuously weld at least three sheets of different steel sheets while moving the two-stage and three-stage ball conveyors, effectively responding to changes in product specifications in one working environment, and working environment and production management. It is to provide a mash seam welding apparatus and a method for providing flexibility to the.

1 is a perspective view schematically showing a mesh seam welding apparatus according to the present invention.

Figure 2 is a schematic plan view schematically showing the main configuration of the mash seam welding apparatus according to the present invention.

Figure 3 is a schematic diagram showing a welding sequence according to an embodiment of the mash seam welding apparatus according to the present invention.

4 is a view showing a two-stage welding process according to an embodiment of a mesh seam welding apparatus according to the present invention.

5 is a view showing a three-stage welding process according to an embodiment of the mesh seam welding apparatus according to the present invention.

6 is a partial front view of a mash seam welding device according to the prior art.

In order to achieve the above object, the mash seam welding apparatus according to the present invention comprises: a conveyor apparatus for supplying a preceding steel sheet and a trailing steel sheet to be welded; Clamping means for overlapping and fixing the preceding steel plate and the following steel plate on the conveyor apparatus; By installing the upper and lower electrode wheels connected to the pressure cylinder on one side to advance and overlap the overlap section of the preceding steel plate and the following steel plate fixed by the clamping means, the overlap section is piezoelectrically welded by the upper and lower electrode wheels. A welder body; In the mesh seam welding apparatus comprising a forward and backward drive motor for providing the forward and backward driving force by the rack pinion structure to advance the welder body forward and backward,

The conveyor apparatus consists of two sets of ball conveyors, each of which has two rows, and is divided into a two-stage ball conveyor and a three-stage ball conveyor having the clamping means, respectively. The jaw is constituted by pushing means for pushing the preceding and trailing steel plates into the clamping means, respectively.

The lower part of the welder body is characterized in that it further comprises a left and right moving means to slide in parallel in the longitudinal direction with respect to the two-stage and three-stage ball conveyor,

The pushing means is installed between the rows of the first and second sets of the two-stage ball conveyor with the clamping means centered on each other so as to be symmetrical to each other, and operated by hydraulic pressure to right and left of the clamping means, respectively. Two-stage leading and second-stage trailing pushers; A three-stage first, which is installed on one side of each of the first and second sets of the three-stage ball conveyors and is operated by hydraulic pressure to push two preceding steel sheets in order to one side of the clamping means in order. A second leading pusher; Between each row of the first and second sets of the three-stage ball conveyor, the chuck is integrally installed on the other side of the clamping means so as to be operated by hydraulic pressure to push or pull the trailing steel plate to the other side of the clamping means. Characterized in that consisting of a three-stage trailing pusher configured to install,

The left and right moving means are arranged side by side in the longitudinal direction with respect to the two-stage and three-stage ball conveyor, the slide rail is configured in the longitudinal direction on one side end; It is configured at the lower part of the welder body to enable the front and rear slide movement by the front and rear movement drive motor connected to the rack pinion structure, and configured to be able to slide in parallel to the left and right in parallel with the welder body along the slide rail. A base frame; The pinion is mounted on one side of the base frame and is engaged with the rack of the slide rail to the rotating shaft, characterized in that consisting of a left and right drive motor for providing a slide driving force to the base frame,

The clamping means is divided into a preceding clamp for clamping the preceding steel plate and a trailing clamp for clamping the subsequent steel plate, and hydraulic cylinders mounted on the front and rear sides of the two-stage and three-stage ball conveyors, respectively; An upper clamp member connected to an upper end of the piston rod of the hydraulic cylinder; Characterized in that the lower clamp member is installed on the same line as the two-stage and three-stage ball conveyor in the lower portion of the upper clamp member.

And the welding method by the mash seam welding apparatus according to the present invention overlaps the preceding steel plate and the following steel sheet on the conveyor device, and then fixed through the clamping means, respectively, the overlap through the upper and lower electrode wheels interlocking with the welder body In the welding method of the mash seam welding device to weld the section by piezoelectric agglomeration,

The conveyor apparatus is divided into a two-stage ball conveyor for welding two sheets of steel sheet and a three-stage ball conveyor for welding three sheets of steel sheet, and a welder body is connected to the two-stage ball conveyor along a longitudinal direction on one side of the conveyor. It is characterized in that the slide can be moved to move between the three-stage ball conveyor to weld a plurality of steel plates by the upper and lower electrode wheels through the two-stage welding process and the three-stage welding process,

The two-stage welding process includes a first step of disposing the preceding and following steel sheets on both sides of the two-stage ball conveyor with the preceding and trailing clamps interposed therebetween; A second step of pushing the preceding steel plate through the two-stage preceding pusher and clamping it with the preceding clamp; A third step of pushing the trailing steel plate through the two-stage trailing pusher to overlap with the preceding steel plate after the second step, and then clamping it with a trailing clamp; And a fourth step of advancing the welder body forward and backward to weld the piezoelectric agglomerate to the overlap section of the preceding and the following steel sheets by upper and lower electrode wheels.

The three-stage welding process includes a first step of disposing the first and second leading steel sheets and the following steel sheets on both sides of the three-stage ball conveyor with the preceding and trailing clamps interposed therebetween; A second step of pushing the first leading steel sheet through a three-step first leading pusher and clamping the first clamp after the first step; A third step of pushing the trailing steel plate through the three-stage trailing pusher to overlap one end of the first leading steel sheet after the second step, and clamping the trailing clamp; A fourth step of firstly welding the main body of the welder forward and backward from the third step by piezoelectric agglomeration between the overlapping sections of the first leading steel plate and the subsequent steel plate by upper and lower electrode wheels; A fifth step of clamping the other end of the first leading steel plate side again with the trailing clamp, among the primary welded steel sheets, while drawing out the first welded steel sheet through the chuck integrally formed with the third stage trailing pusher after the fourth step; Steps; A sixth step of pushing the second leading steel sheet through the three-stage second leading pusher to overlap the primary welded steel sheet and clamping the preceding clamp after the fifth step; The welding machine main body is moved back and forth again, and the seventh step of secondary welding by piezoelectric pulverizing the overlap section of the second leading steel sheet and the primary welded steel sheet by the upper and lower electrode wheels.

Hereinafter, the preferred configuration and operation of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view schematically showing a mash seam welding apparatus according to the present invention, Figure 2 is a schematic plan view schematically showing the main configuration of the mash seam welding apparatus according to the present invention, The welding apparatus includes a conveyor apparatus 10 for supplying a welded steel sheet, a clamping means 20 for fixing the welded steel sheet on the conveyor apparatus 10, and a welder for piezoelectric agglomeration of the welded steel sheet by an electrode wheel. A forward and backward drive motor 43 for providing a forward and backward driving force to the main body 30 and the welder main body 30, pushing means for pushing the welded steel sheet into the clamping means 20, and the welder main body ( It consists of a left and right moving means 40 for sliding 30 in parallel with respect to the conveyor device (10).

The welded steel sheet is divided into preceding steel sheets 50, 51 and 52, which are first introduced into the clamping means 20 by the pushing means, and subsequent steel sheets 60 and 61, which are subsequently introduced.

And the conveyor apparatus 10 is composed of two pairs of ball conveyor consisting of two rows, this ball conveyor is again a two-stage ball conveyor 11 for welding two sheets of steel and three stages for welding three sheets of steel It is divided into a ball conveyor 12, and the clamping means 20 and the pushing means are configured, respectively.

In this case, the pushing means is configured in the first (13, 14) and the second (15, 16) of the two-stage and three-stage ball conveyor (11, 12), respectively, the preceding and following steel sheet (50, 51) , 52, 60 and 61 are pushed into the clamping means 20.

The clamping means 20 is a two-stage and three-stage leading clamps 21 and 22 for clamping the leading ends of the preceding steel sheets 50, 51 and 52, which are introduced by the pushing device, and the leading ends of the following steel sheets 60 and 61. Is divided into two-stage and three-stage trailing clamps (23, 24) clamped in the state overlapping with the preceding steel sheets (50, 51), each of the configuration is the two-stage and three-stage ball conveyor (11, 12) The hydraulic cylinder 25 is mounted on the line and the trailing side of the upper side, respectively, and the upper clamp member 25 is connected to the upper end of the piston rod of the hydraulic cylinder 27, respectively. The lower clamp member 26 is provided on the same line as the single and three stage ball conveyors 11 and 12.

And the pushing means is a two-stage leading and two-stage symmetrical with each other on both sides of the clamping means (20) between the rows of the first, second set (13, 15) of the two-stage ball conveyor (11) The trailing pushers 71 and 72 are installed to operate by hydraulic pressure to push the leading and trailing steel sheets 50 and 60 to the two-stage line and the trailing clamps 21 and 23, respectively.

In addition, between the rows of the first and second pairs 14 and 16 of the three-stage ball conveyor 12, three-stage first and second leading pushers 73 and 75 on one side of the clamping means 20. Is installed and operated by hydraulic pressure so as to push the two preceding steel sheets 51 and 52 to the three stage preceding clamp 22 in sequence, and the third stage trailing pusher 74 on the other side of the clamping means 20. Is installed and operated by hydraulic pressure is configured by integrally installing a chuck (not shown) to push or pull the trailing steel plate 61 to the three-stage trailing clamp 24.

The left and right moving means 40 is a slide rail 41 is arranged side by side in the longitudinal direction with respect to the two-stage and three-stage ball conveyor (11, 12), one side end of the slide rail 41 along the longitudinal direction The rack 42 is configured. In addition, the lower portion of the welder body 30 is connected to the front and rear movement drive motor 43 by using the rack pinion structure to enable the front and rear slide movement, and the welder body 30 along the slide rail (41). The base frame 44 is configured to be able to slide in parallel to the left and right directions.

And one side of the base frame 44 is mounted to the pinion 45 engaged with the rack 42 of the slide rail 41 to the rotating shaft to provide a slide driving force to the base frame 44, the left and right drive motor 46 It is possible to slide the welder main body 30 in parallel with the two-stage and three-stage ball conveyors (11, 12) in the longitudinal direction.

Therefore, the welding method according to the mash seam welding apparatus according to the present invention having the configuration as described above overlaps the preceding steel sheets (50, 51, 52) and the following steel sheets (60, 61) on the ball conveyor, and then precede and follow By fixing the clamps 21, 22, 23, 24, respectively, as the welding machine main body 30 advances back and forth, the overlap section is piezoelectrically agglomerated through the upper and lower electrode wheels 80 and 81 that interlock with each other. Weld

At this time, as shown in Figure 3, the ball conveyor is divided into a two-stage ball conveyor 11 for welding two sheets of steel sheet and a three-stage ball conveyor 12 for welding three steel sheets, the ball On one side of the conveyor, the welder main body 30 is slidably movable to move between the two-stage ball conveyor 11 and the three-stage ball conveyor 12 along the longitudinal direction, so that the two-stage welding process (A) and three However, a plurality of steel sheets are welded through the welding process (B).

Here, the two-stage welding process (A), as shown in Figure 4, on the two-stage ball conveyor (11) with the two-stage leading and trailing clamps (21, 23) between both leading and trailing steel plate If (50,60) is arranged (FIG. 4 (a)), then, the two-stage preceding pusher 71 is operated to push the preceding steel plate 50 and put it into the two-stage preceding clamp 21. The preceding clamp 21 clamps the leading end of the preceding steel plate 50 (Fig. 4 (b)).

Thereafter, by operating the two-stage trailing pusher 72 to push the trailing steel sheet 60, the two-stage trailing clamp 23 is introduced into the second-stage trailing clamp 23 to overlap with the preceding steel sheet 50, and then the two-stage trailing clamp 23. The tip of the trailing steel sheet 60 is clamped (FIG. 4C).

Here, the operation of the two-stage line, trailing clamps (21, 23) is connected to the upper end of the piston rod of each hydraulic cylinder (27) mounted on the line, the trailing side of the two-stage ball conveyor 11 is operated upwards When the upper clamp member 25 is lifted and the preceding or trailing steel sheets 50 and 60 are introduced between the upper and lower clamp members 25 and 26 by two-stage line and trailing pushers 71 and 72, The hydraulic cylinder 27 is operated downward to lower the upper clamp member 25 and clamp it together with the lower clamp member 26.

As such, when the preceding and following steel sheets 50 and 60 are fixed by the two-stage line and the following clamps 71 and 72 in the state of overlapping with each other, the welder main body 30 is moved forward and backward so that upper and lower electrode wheels ( The overlapping sections of the preceding and following steel sheets 50 and 60 are piezoelectrically agglomerated and welded by 80 and 81 (FIG. 4 (d)).

At this time, the upper electrode wheel 80 is provided with a pressing force by the pressure cylinder 83 configured on the upper end of the welder body 30, when welding the overlap section, it is pressed simultaneously with the welding.

In the three-stage welding process, as shown in FIG. 5, the welder main body 30 moves the left and right moving drive motors 46 formed on one side of the base frame 44 on one side of the two-stage ball conveyor 11. After moving to move to one side of the three-stage ball conveyor 12 by the operation of the rack 42 configured on the side end portion of the slide rail 41 and the pinion 45 configured on the rotary shaft of the left-right moving drive motor 46,

When the first and second leading steel sheets 51 and 52 and the trailing steel sheets 61 are disposed on both sides of the three-stage ball conveyor 12 with the three-stage leading and trailing clamps 22 and 24 interposed therebetween (Fig. 5 (a)), and then, by operating the three-stage first leading pusher 73 to push the first leading steel plate 51 and inserting it into the three-stage preceding clamp 22, the three-stage preceding clamp 22 is The distal end of the first leading steel plate 51 is clamped (FIG. 5B).

Thereafter, the three-stage trailing pusher 74 is operated to push the trailing steel plate 61, and the three-stage trailing clamp 24 is introduced into the three-stage trailing clamp 24 to overlap the first leading steel sheet 51, and then the three-stage trailing clamp 24 is operated. ), The leading end of the trailing steel sheet 61 is clamped (Fig. 5 (c)).

Here, the operation of the three-stage line, trailing clamps 22 and 24 is the same as the operation of the two-stage line and the trailing clamps 21 and 23, and thus will be omitted.

As described above, when the first leading and trailing steel plates 51 and 61 are fixed by the three-stage line and trailing clamps 22 and 24 in the state of overlapping with each other, the welder main body 30 is moved back and forth to raise and lower the upper and lower electrodes. By the wheels 80 and 81, the overlap sections of the first leading and trailing steel plates 51 and 61 are piezoelectrically agglomerated to perform primary welding.

At this time, the upper electrode wheel 80 is provided with a pressing force by the pressure cylinder 83 configured on the upper end of the welder body 30, when welding the overlap section, it is pressed simultaneously with the welding.

Subsequently, the primary welded steel plate 62 is pulled out of the primary welded steel plate 62 while pulling out the primary welded steel plate 62 through a chuck (not shown) integrally formed with the three-stage trailing pusher 74. The other end is clamped back to the three-stage trailing clamp 24 (FIG. 5 (d)).

The second leading steel plate 52 is pushed through the three-stage second leading pusher 75 to overlap with the primary welded steel plate 62, and then clamped to the three-stage preceding clamp 22, and the welder main body ( 30 is moved back and forth again to perform secondary welding by piezoelectric agglomeration between the overlapping sections of the second leading steel sheet 52 and the primary welded steel sheet 62 by the upper and lower electrode wheels 80 and 81 (FIG. 5 (e)).

Therefore, according to the mash seam welding apparatus and the method according to the present invention, the welder main body 30 moves the two-stage and three-stage ball conveyors 11 and 12 in order to weld two or three steel sheets, and continuously By welding, the parts can be directly applied without waiting for parts that are applied at the same location, thereby reducing the burden of inventory, increasing production capacity, and actively responding to changes in rapidly changing parts.

As described above, according to the mash seam welding apparatus and method according to the present invention, the welder main body is divided into two- and three-stage ball conveyors by applying a base frame so that the slide can move in parallel. It is possible to continuously weld at least three sheets of dissimilar steel sheets while moving two-stage and three-stage ball conveyors, and it is possible to effectively respond to changes in product specifications in one working environment, There is an effect that can improve the productivity.

Claims (7)

A conveyor device for supplying a preceding steel sheet and a subsequent steel sheet to be welded; Clamping means for overlapping and fixing the preceding steel plate and the following steel plate on the conveyor apparatus; By installing the upper and lower electrode wheels connected to the pressure cylinder on one side to advance and overlap the overlap section of the preceding steel plate and the following steel plate fixed by the clamping means, the overlap section is piezoelectrically welded by the upper and lower electrode wheels. A welder body; In the mesh seam welding apparatus comprising a forward and backward drive motor for providing the forward and backward driving force by the rack pinion structure to advance the welder body forward and backward, The conveyor apparatus consists of two sets of ball conveyors, each of which has two rows, and is divided into a two-stage ball conveyor and a three-stage ball conveyor having the clamping means, respectively. The jaw is constituted by pushing means for pushing the preceding and trailing steel plates into the clamping means, respectively. The lower part of the welder main body is a mash seam welding device further comprises a left and right moving means to slide in parallel in the longitudinal direction with respect to the two-stage and three-stage ball conveyor. The method of claim 1, wherein the pushing means Between the rows of the first and second sets of the two-stage ball conveyor, each of the clamping means is centered on each other and symmetrically installed on both sides to operate by hydraulic pressure to push the leading and trailing steel plates to the left and right of the clamping means, respectively. With only preceding and two-stage trailing pushers; A three-stage first, which is installed on one side of each of the first and second sets of the three-stage ball conveyors and is operated by hydraulic pressure to push two preceding steel sheets in order to one side of the clamping means in order. A second leading pusher; Between each row of the first and second sets of the three-stage ball conveyor, the chuck is integrally installed on the other side of the clamping means so as to be operated by hydraulic pressure to push or pull the trailing steel plate to the other side of the clamping means. A mash seam welding device comprising: a three-stage trailing pusher configured to be installed. The method of claim 1, wherein the left and right moving means A slide rail disposed side by side in the longitudinal direction with respect to the two-stage and three-stage ball conveyors, and having a rack configured in a longitudinal direction at one end thereof; It is configured in the lower part of the welder body to enable the front and rear slide movement by the front and rear movement drive motor connected to the rack pinion structure, and configured to be able to slide in parallel to the left and right in parallel with the welder body along the slide rail. A base frame; A mesh seam welding apparatus, comprising: a left and right moving drive motor mounted on one side of the base frame to mount a pinion engaged with a rack of the slide rail to a rotating shaft to provide a slide driving force to the base frame. The method of claim 1 or 2, wherein the clamping means A preceding clamp for clamping the preceding steel sheet and a trailing clamp for clamping the subsequent steel sheet, Hydraulic cylinders mounted on the front and rear sides of the two-stage and three-stage ball conveyors, respectively; An upper clamp member connected to an upper end of the piston rod of the hydraulic cylinder; A mash seam welding apparatus comprising a lower clamp member installed on the same line as the two-stage and three-stage ball conveyors under the upper clamp member. Welding method of the mash seam welding apparatus which overlaps the preceding steel plate and the following steel plate on the conveyor apparatus, and fixes them by clamping means, respectively, and piezoelectrically aggregates the overlap section through upper and lower electrode wheels interlocked with the welder main body. To The conveyor apparatus is divided into a two-stage ball conveyor for welding two sheets of steel sheet and a three-stage ball conveyor for welding three sheets of steel sheet, and a welder body is connected to the two-stage ball conveyor along a longitudinal direction on one side of the conveyor. Mash seam welding, characterized in that the slide can be moved so as to move between the three-stage ball conveyor so that a plurality of steel plates can be welded by the upper and lower electrode wheels through the two-stage welding process and the three-stage welding process. Way. The method of claim 5, wherein the two-stage welding process A first step of arranging the leading and trailing steel plates on both sides of the ball conveyor with the preceding and trailing clamps interposed therebetween; A second step of pushing the preceding steel plate through the two-stage preceding pusher and clamping it with the preceding clamp; A third step of pushing the trailing steel plate through the two-stage trailing pusher to overlap with the preceding steel plate after the second step, and then clamping it with a trailing clamp; And a fourth step in which the welder main body is moved forward and backward to piezoelectric agglomerate and weld the overlapping sections of the preceding and following steel sheets by upper and lower electrode wheels. The method of claim 5, wherein the three-stage welding process A first step of disposing first and second leading steel sheets and trailing steel sheets on both sides of the three-stage ball conveyor with the preceding and trailing clamps interposed therebetween; A second step of pushing the first leading steel sheet through a three-step first leading pusher and clamping the first clamp after the first step; A third step of pushing the trailing steel plate through the three-stage trailing pusher to overlap one end of the first leading steel sheet after the second step, and clamping the trailing clamp; A fourth step of firstly welding the main body of the welder forward and backward from the third step by piezoelectric agglomeration between the overlapping sections of the first leading steel plate and the subsequent steel plate by upper and lower electrode wheels; A fifth step of clamping the other end of the first leading steel plate side again with the trailing clamp, among the primary welded steel sheets, while drawing out the first welded steel sheet through the chuck integrally formed with the third stage trailing pusher after the fourth step; Steps; A sixth step of pushing the second leading steel sheet through the three-stage second leading pusher to overlap the primary welded steel sheet and clamping the preceding clamp after the fifth step; The seventh step of the mash seam welding method comprising the seventh step of performing the second welding by welding the main body of the welder back and forth and the piezoelectric agglomeration of the overlap section of the second leading steel sheet and the primary welded steel sheet by the upper and lower electrode wheels. .