JP2010105018A - Method for manufacturing welded can body, welded can body, and device for manufacturing welded can body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a welded can body, which has excellent repair weldability of a seam welded edge, to provide a welded can body, and to provide a device for manufacturing a welded can body. <P>SOLUTION: In the method, a welded can body 12 is manufactured by superposing edge parts 10a, 10b of a metal blank, which are opposed to each other, to form a can-body shape 10 with a superposed portion 10c, and by bringing linear electrodes 3, 4 respectively into contact with both surfaces of the superposed portion 10c to perform electric resistance mash seam welding. An outside edge C1 is shape-formed by radiating a laser beam L along the outside edge C1 of a seam welded portion B to melt the outside edge C1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a welded can body used for beverages, a welded can body, and an apparatus for manufacturing a welded can body.

  A welded can body used for a coffee beverage can or the like is usually manufactured by overlaying opposing edge portions of a metal blank such as a tin-plated steel plate and welding the overlapped portion with an electric resistance mash seam. However, on the side of the mash seam welded portion, a step portion having a relatively steep slope and an irregular cross-section or a hollow portion is formed (C1 and C2 portions in FIG. 4). In order to prevent rusting and corrosion due to contents, this weld is usually repaired by applying paint and drying to form a paint film. There is a problem that it is easy to produce a missing part or a part where the coating film is very thin, and therefore it is difficult to obtain a satisfactory repair effect.

  In order to solve the above problem, Patent Document 1 or Patent Document 2 discloses a method of reducing the step by devising the shape of the wire electrode used for electric mash seam welding.

  Patent Document 3 discloses a method for manufacturing a welding can body that uses a laser for welding to reduce the level difference of the welded portion.

  However, in the invention of Patent Document 1 or Patent Document 2, the welding state fluctuates due to a slight change in the contact state with the electrode, so that it is not always possible to obtain a sufficient effect for the elimination of the step and the gap portion. was there. Moreover, in the welding method by the laser described in patent document 3, when welding the very thin metal blank about 0.1-0.2 mm of plate | board thickness used for a normal drink can, the metal blank edge of a welding part is carried out. There is a problem that poor welding is likely to occur due to a slight change in the degree of overlap.

JP-A-62-275582 Japanese Unexamined Patent Publication No. 63-149087 JP-A-61-202789

  As described above, the welded can body has a stepped portion and a burrow in the welded portion, and the stepped portion is repaired by applying a rust and anticorrosion coating, but the coating thickness is reduced at the corners of the stepped portion. In addition, there is a problem that coating failure is likely to occur, such as the paint does not reach the hollowed portion and a void is formed, and corrosion and rust are generated in the welded portion.

  An object of the present invention is to provide a welded can body, a manufacturing method and an apparatus for manufacturing a welded can body, in which the above-described problems are solved and the repairability of a welded portion by paint is improved.

  As a result of investigations to solve the above problems, the inventors of the present invention irradiate a seam weld end of electric resistance mash seam welding to melt the seam weld end, and determine the surface tension at the time of melting. It was discovered that by using the shape of the end to make use of it, it was possible to eliminate the problem of the level difference in the end of the weld seam and the gap.

  That is, the present invention is as follows.

  In the method for manufacturing a welded can body of the present invention, opposing edge portions of a metal blank are overlapped to form a can body formed body having an overlap portion, and line electrodes are brought into contact with both surfaces of the overlap portion, respectively. In the method of manufacturing a welded can body by welding an electric resistance mash seam, a laser beam is irradiated along the outer end of the seam welded portion of the welded can body that has been mash seam welded. The outer end portion is shaped by melting the end portion.

  The method for manufacturing a welding can body according to the present invention is characterized in that the laser beam is irradiated during a transfer movement between a mash seam welding step and a step of applying a corrosion-preventing coating to the seam welded portion. .

  The welding can body of the present invention is formed by superposing the opposing edge portions of the metal blank to form a can body forming body having the overlapping portion, and contacting the line electrodes on both surfaces of the overlapping portion, respectively. In a welding can body manufactured by resistance mash seam welding, after the seam welding process, the outer end is melted by irradiating a laser beam along the outer end of the seam weld. The part is shaped and processed.

  In the welding can body of the present invention, the dimension of the outer end melted by the laser beam irradiation is a melting depth of 50% or more of the step of the outer end, and 50% of the step of the outer end. It is the above melting width.

  The apparatus for manufacturing a welded can body of the present invention forms a can body forming body having an overlapped portion by superimposing the opposing edge portions of a metal blank, and makes line electrodes contact with both surfaces of the overlapped portion, respectively. In a welding can barrel manufacturing apparatus that manufactures a welded can barrel by electric resistance mash seam welding, a seam weld end portion is provided between the mash seam welding mechanism and a coating mechanism for applying a corrosion-preventing coating to the seam welded portion. As a laser beam irradiation mechanism for irradiating a laser beam, a laser oscillator and a laser focusing optical mechanism are provided.

  In the welding can barrel manufacturing apparatus according to the present invention, the laser beam irradiation mechanism includes a sensor that detects a passing position of the welding can barrel, and starts and stops oscillation of the laser oscillator based on a detection signal of the sensor. It is characterized by having a mechanism to control.

  In the welding can barrel manufacturing apparatus of the present invention, the laser beam irradiation mechanism includes a sensor that detects a seam weld line position of mash seam welding, and a control mechanism that controls the laser beam irradiation position based on a seam position detection signal from the sensor. It is characterized by having.

  According to the present invention, the shape of the mash seam weld end portion of the weld can body is improved, and the problem of the occurrence of a step or a hollow portion at the end portion is solved. According to the present invention, it is possible to obtain a welded can body in which the overlapping portion of the edge portion has a curved cross section smoothly connected at the welded portion, and the repairability of the welded portion by the paint is improved. That is, it is possible to provide a welded can body excellent in corrosion resistance paint resistance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a diagram showing an outline of the present invention. The welded can body 12 is formed by stacking opposing end edges of a can body preform formed of a metal blank such as tin-plated steel plate, tin-free steel, ultra-thin nickel-plated steel plate, or ultra-thin nickel / tin composite-plated steel plate. In addition, the overlapping portion is formed by electric resistance mash seam welding. In the present invention, the laser beam L is irradiated along the seam weld line 13 outside the seam weld B of the weld can body 12 to melt the outer end of the seam weld B, and the surface tension generated at the time of melting is melted. The shape of the outer end portion of the seam weld B is shaped using the action. In FIG. 1, D shows a laser irradiation completion part.

  FIG. 2 shows an outline of the configuration of a manufacturing apparatus that implements the present invention. In FIG. 2, 1 is an internal electrode roll, 2 is an external electrode roll, and 3 and 4 are a first line electrode and a second line electrode supported by the internal electrode roll 1 and the external electrode roll 2 during welding, respectively. 5 is a mandrel.

  As shown in FIG. 3, the metal blank is molded into a cylindrical can body preform 10 and moved in the direction of the arrow Z in FIG. 2, while the outer edge 10a and the inner side of the can body preform 10 face each other. The overlapping portion 10c with the end edge portion 10b is welded (mash seam welding) by being pressed and energized by the pair of wire electrodes 3 and 4, and the welding can body 12 is manufactured.

  By mash seam welding, the edge portions 10a and 10b are reduced in order to reduce the difference in thickness of the overlapped portion 10c (normally, the thickness of the overlap welded portion is about 1.1 to 1.8 times the thickness of the metal blank). 4), as shown in the cross-sectional photograph of the welded portion in FIG. 4, a shape having a step or a minute burred portion is left at the can inner end portion C2 and the outer end portion C1 of the seam welded portion. .

  After the completion of welding, the outer end C1 having the step ho shown in FIG. 4 is painted and repaired by the repair coating apparatus 6 (FIG. 2) for applying a rust and anticorrosion paint. However, at the corner portion of the outer end C1, the coating thickness becomes thin, or coating failure such as the formation of a cavity due to the paint not reaching the corner portion is likely to occur, which causes corrosion and rust in the seam welded portion B. There was a problem.

  The welding can barrel manufacturing apparatus of the present invention has a laser beam irradiation mechanism 20 shown in FIG. For convenience of illustration, the laser beam irradiation mechanism 20 is irradiated with the laser beam L emitted in parallel to the arrow Z from the laser oscillator 21 by being bent in the direction of the welding can body 12 (downward) by the reflection mirror 22. However, as will be described later, in order to control the laser beam irradiation position in accordance with the change in the position of the seam weld line, the actual laser beam irradiation mechanism 20 is rotated in a direction perpendicular to the paper surface. Is installed.

  Before the seam welded portion B is subjected to the repair coating by the repair coating device 6, the laser beam L is irradiated aiming at the outer end C1 of the seam welded portion B. FIG. 5 shows a cross-sectional photograph of the overlapped portion 10c in which the shape of the end is shaped by laser light irradiation. The outer step C1 in FIG. 4 is melted by irradiating the laser beam, and the step and the sag portion formed on the outer side of the seam weld end by utilizing the action of the surface tension at the time of resolidification are shown in FIG. It is possible to obtain a cross-sectional shape that is shaped like the end portion C11 so that the outer end edge portion 10a gently connects to the surface of the inner end edge portion 10b. Since the outer end C11 in FIG. 5 is smooth, the rust-proof and anti-corrosion paint is uniformly applied, and sufficient rust and corrosion resistance can be ensured.

  The present invention irradiates a laser beam to the outer end of the seam welded portion B of the welding can body 12 during the transfer movement between the mash seam welding step and the step of applying a corrosion prevention coating to the seam welded portion B. In addition, by using only a laser device and an optical mechanism related to laser light irradiation as a mechanism necessary for laser light irradiation, a laser beam scanning over the entire moving mechanism of the welding can barrel 12 and the entire length of the seam weld B is performed. Therefore, it is possible to realize an inexpensive and simple manufacturing apparatus for a welding can body.

  In the present invention, a welding can body detector 31 shown in FIG. 2 is provided as a sensor for detecting the passing position of the welding can body, the position of the welding can body 12 in the Z direction is detected, and welding is performed below the laser light irradiation position L0. Laser oscillation is started at the timing when the can body 12 moves, and the laser light irradiation is stopped at the timing when the welding can body 12 completes passing through the laser light irradiation position L0. By stopping the laser oscillation when the welding can body 12 is not present, it is possible to prevent the apparatus body from being irradiated with laser light and prevent damage to the apparatus.

  In a normal can making apparatus, a Z-shaped guide rail 41 shown in FIG. 6 is used in order to accurately mold the overlap portion during mash seam welding. For this reason, in the stage before mash seam welding, the can body preform 10 formed into a cylindrical shape is limited in the degree of freedom of rotation, and the outer edge portion 10a and the inner edge portion 10b are overlapped. The position of the part does not shift in the circumferential direction. However, after the mash seam welding is completed, the cylindrical welding can body 12 is formed, so that it is restrained by the guide roll 41, but the seam weld line 13 position by the rotation in the circumferential direction is moved during the next process. Deviation occurs. In addition, at both ends of the welding can body 12, the amount of heat generated at the time of welding increases, so the deformation of the seam overlap portion due to the pressurization at the time of welding is large, and the position of the seam weld line 13 bends in the circumferential direction. There is.

  According to the study by the present inventors, the fluctuation width of the seam weld line 13 due to the above rotation and bending is usually about 0 to 0.5 mm. Therefore, even when the seam weld line position is changed, the beam diameter in the orthogonal direction of the seam weld line 13 is set to 1 mm as the beam diameter irradiated with the laser beam to the seam weld B. Even if the seam weld line position fluctuates during the transport movement of 12, the seam weld outer end C1 can be reliably irradiated with laser light.

  Further, according to the present invention, a welding line detector 30 (FIG. 2) is provided as a sensor for detecting the position of the seam weld line, which is a camera image sensor that detects the position of the seam weld line 13 coaxially with the laser beam to be irradiated. The laser beam reflecting mirror 22 installed in front of the condensing lens 23 is, for example, a galvanometer mirror, and controls the setting angle of the reflecting mirror 22 based on the detection signal of the welding line detector 30 to control the seam welding line 13. The beam position can be corrected so that the end is irradiated with laser light. Thus, by providing a mechanism for controlling the laser beam irradiation position according to the variation of the seam welding line 13, it is not always necessary to set the laser spot diameter to 1 mm, and is generally about 10 μm to 0.5 mmφ. Processing is possible even with a laser beam having a small focused spot diameter.

  The detection of the seam weld line position is not necessarily limited to the image detection method by the image sensor, and for example, using the temperature distribution measurement result of the temperature sensor of the weld seam part generally used for detecting the seam welding failure. A method for detecting the seam welding position can also be used. Alternatively, a method of condensing a laser beam on a linear spot and irradiating the seam welded portion and detecting a seam weld end from the shape change of the linear laser spot can be used.

  In addition to the galvanometer mirror, a beam driving method using an acousto-optic element can be used as the laser beam irradiation position driving means. Further, by using an fθ lens as the condensing lens, it is possible to obtain a stable laser condensing that eliminates the influence of aberrations and the like that occur during beam driving.

  Furthermore, if the laser beam irradiation position is in the range of A part in FIG. 2 (immediately after electric resistance seam welding and the unwelded part is restrained by the Z-type guide rail 41 in FIG. 6), Z in FIG. Since the variation of the seam welding position is suppressed by restraint by the guide rail 41 of the mold, the laser beam irradiation can be performed more stably on the seam welding outer end C1.

  7A to 7C are enlarged cross-sectional views showing the state of laser light irradiation in the vicinity of the seam weld B. B0 is a weld line of the lap part welded by electric resistance seam welding. As shown in FIGS. 7A to 7C, in the present invention, the laser beam L is irradiated so as to include the seam weld outer end C1. Moreover, as shown in FIG. 8, you may irradiate the laser beam L from diagonally upward outside the seam welding outer end C1. The thickness of the metal blank used for the welding can body is usually very thin, about 0.1 to 0.3 mm, and the welded portion is subjected to pressure deformation due to pressurization during seam welding. Usually, it is relatively small, about 0.01 to 0.2 mm. Therefore, as shown in FIG. 7A, the seam weld outer end C1 is irradiated with laser light L from substantially vertically above, and as shown in FIG. 8, the seam weld outer end C1 is aimed obliquely from above. There is no significant difference in the melt shapeability of the seam weld outer end C1 when the laser beam L is irradiated, and the irradiation direction of the laser beam L is from the direction in which the laser beam L is easily irradiated due to the apparatus configuration of the welding machine. Irradiation is sufficient.

  Moreover, in this invention, it was set as the laser beam irradiation conditions which obtain 50% or more of the fusion depth h and the melt width w of the level | step difference ho (FIG. 4) of the seam welding outer side end C1 before laser beam irradiation.

  The condensing spot shape d of the laser beam of the present invention is not necessarily limited to a circle as shown in FIGS. 7 and 8, and the outer end of seam welding, which is the gist of the present invention, is irradiated with the laser beam. A laser beam having a condensing spot shape such as a linear shape or an elliptical shape can be used as long as it meets the purpose and satisfies the above-described molten state.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  The present inventors investigated and examined the relationship between the laser processing conditions such as the laser beam irradiation position, laser output, laser beam irradiation speed, and laser beam focusing shape, and the shaped shape after melting of the seam weld outer end C1. . That is, under the laser light irradiation conditions obtained by combining various laser outputs, laser light irradiation speeds, and laser light condensing shapes, the metal blank ingot 42 shown in FIG. On the basis of the melt depth h and the surface melt width w, the melt-shaped shapes of the seam weld outer end C1 were compared and examined.

Table 1 shows an example of the welding conditions studied, the melting depth h, the melting width w obtained by irradiation of the metal blank metal 42 in FIG. 9, and the step ho of the seam welding outer end C1 before laser light irradiation. (FIG. 4) and the result of shape evaluation of the seam weld outer end C11 (FIG. 5) after laser light irradiation under the same laser light irradiation conditions are shown. A mark ◯ shows that the step and gap between the outer edge portion 10a and the inner edge portion 10b have been eliminated in the seam welded portion B after the laser beam irradiation. A cross indicates that the step or gap between the outer edge portion 10a and the inner edge portion 10b remained in the seam welded portion B even after the laser beam irradiation. Note that the laser beam irradiation was performed in an N ₂ purge atmosphere. In Table 1, numerical values with an underline are portions that do not satisfy the conditions of the present invention.

  In the processing under various laser light irradiation conditions, the step of the seam weld outer end C1 is performed under the condition that the melting depth h and the melting width w are both 50% or more of the initial step height (step ho). And the excuse was resolved. The reason why the laser beam irradiation condition does not need to be the condition for melting the entire initial level difference ho is that the level difference of the seam weld outer end C1 that irradiates the laser beam is the end of the metal blank. Since the direction in which the applied heat escapes is limited to one side where the metal blank base material exists, melting can be achieved more efficiently than a metal blank that can diffuse heat in the left-right direction, resulting in less input heat. This is because the entire step is melted, and melting sufficient to eliminate the step ho can be obtained.

  From the above, in order to shape the seam weld outer end C1 into a gentle shape effective for repair coating after welding, a melting depth of 50% or more of the step ho of the seam weld outer end C1 before laser light irradiation. It was found that it was necessary to use laser light irradiation conditions for obtaining h and melt width w.

  Below, the Example which manufactured the welding can body is shown. In the examples, a metal blank of tin-free steel was used. However, any metal blank such as tin-plated steel, tin-free steel, ultra-thin nickel-plated steel, ultra-thin nickel / tin composite-plated steel can be used. Materials may be used.

  Further, in this embodiment, the laser beam is irradiated to the seam welded portion through the very complicated mechanical structure in the vicinity of the continuous can mechanism, welding mechanism, and repair coating mechanism of the mash seam welder. A fiber laser was used in consideration of the fact that the light exit port is small, has excellent installation flexibility, has excellent condensing performance, and can obtain a small condensing diameter of 1.0 mmφ or less even with a long-focus lens. However, any laser can be applied as long as it is generally used for metal processing, such as a carbon dioxide laser, a YAG laser, and a disk laser.

  In addition, by providing a sufficiently wide space between the mash seam welding and the repair coating mechanism, or by moving the welded can body after seam welding to another production line, laser light irradiation such as a semiconductor laser is performed. It is also possible to use a laser that requires space.

A tin-free steel blank having a surface treatment layer comprising a metal chromium layer having a thickness of 0.15 mm, a metal chromium amount of 120 mg / m ² , and a chromium oxide amount of 18 mg / m ² (in terms of metal chromium) Thus, the can body preform 10 having an inner diameter of 52 mm, a width of the overlapping portion of 0.4 mm, and a height of 136 mm was formed without removing the surface treatment layer from the vicinity of the overlapping portion. The overlapping portion 10c (see FIG. 3) of the can body preform 10 was mash seam welded in a nitrogen gas atmosphere using the welding mechanism of the manufacturing apparatus shown in FIG. The current for mash seam welding was 3000 A, the applied pressure during welding was 40 kg, and the moving speed of the can body preform during welding (mash seam welding speed) was 60 m / min. When the seam welded portion was examined after welding, it was confirmed that a step having a step ho = 60 μm was present in the welding under the above welding conditions (comparative example).

As an example according to the present invention, the laser beam irradiation mechanism 20 in FIG. As the laser, a single mode fiber laser with a rated output of 500 W was used, and laser light was condensed and irradiated on the seam weld end with a lens having a focal length of 300 mm. The focused spot diameter of the laser light irradiated at this time was 0.2 mmφ, which is a diameter that is 1 / e ² of the peak value of the output distribution. The laser output was 500 W, and the moving speed in the arrow Z direction of the seam-welded welded barrel was 60 m / min, the same as in mash seam welding. The laser beam was irradiated such that the center of the focused spot diameter matched the corner of the mash seam weld end with the center position of the laser beam. The vicinity of the laser beam irradiation part was maintained in a nitrogen gas atmosphere.

  After the laser beam irradiation, the seam welded portion was subjected to anticorrosion repair coating by the repair coating apparatus 6 to manufacture a welded can body. A series of manufacturing steps were continuously performed with the manufacturing apparatus shown in FIG. When the seam welded portion was examined for the welded can body after production, the step of the seam welded portion that existed in the comparative example in which laser light irradiation was not performed disappeared, and a gentle welded portion was obtained, and the corrosion-resistant paint was uniformly applied. It was confirmed that the weld seam was painted.

Under the same conditions as in Example 2, a can body preform 10 was formed, and mash seam welding was performed. Furthermore, the laser beam irradiation mechanism 20 in FIG. 2 focused and irradiated the laser beam on the seam weld end. As the laser, a single mode fiber laser with a rated output of 500 W was used, and laser light was condensed and irradiated on the seam weld end with a lens having a focal length of 300 mm. The condensing diameter of the laser light irradiated at this time was 0.2 mmφ, which is 1 / e ² of the peak value of the output distribution. The laser output was 500 W, and the moving speed in the direction of arrow Z of the welded can body that had been seam welded was 60 m / min, the same as in mash seam welding. The laser beam was applied to a portion where the center of the focused diameter was 0.08 mm away from the corner of the mash seam weld end (the state shown in FIG. 7B). The vicinity of the laser beam irradiation part was maintained in a nitrogen gas atmosphere.

  After the laser beam irradiation, the seam welded portion was subjected to anticorrosion repair coating by the repair coating apparatus 6 to manufacture a welded can body. A series of manufacturing steps were continuously performed with the manufacturing apparatus shown in FIG. When the seam welded portion was examined for the welded can body after production, the step of the seam welded portion that existed in the comparative example in which laser light irradiation was not performed disappeared, and a gentle welded portion was obtained, and the corrosion-resistant paint was uniform. It was confirmed that the weld seam was painted.

Under the same conditions as in Example 2, a can body preform 10 was formed, and mash seam welding was performed. Further, the laser beam was focused and irradiated to the seam weld end by the laser beam irradiation mechanism 20 in FIG. As the laser, a single mode fiber laser with a rated output of 500 W was used, and laser light was condensed and irradiated on the seam weld end with a lens having a focal length of 300 mm. The focused spot diameter of the laser beam irradiated at this time was 0.2 mmφ, which is a diameter that is 1 / e ² of the peak value of the output distribution. The laser output was 500 W, and the moving speed in the direction of arrow Z of the welded can body that had been seam welded was 60 m / min, the same as in mash seam welding. The center of the focused spot diameter was irradiated so that the center position of the laser beam was 0.08 mm away from the corner portion of the mash seam weld end in the opposite direction to that of Example 2 (FIG. 7). (State shown in (c)). The vicinity of the laser beam irradiation part was maintained in a nitrogen gas atmosphere.

  After the laser beam irradiation, the seam welded portion was subjected to anticorrosion repair coating by the repair coating apparatus 6 to manufacture a welded can body. A series of manufacturing steps were continuously performed with the manufacturing apparatus shown in FIG. When the seam welded portion was examined for the welded can body after production, the step of the seam welded portion that existed in the comparative example in which laser light irradiation was not performed disappeared, and a gentle welded portion was obtained, and the corrosion-resistant paint was uniform. It was confirmed that the weld seam was painted.

  INDUSTRIAL APPLICABILITY The present invention is used as a technique for smoothening the shape of a step or a hollow portion of an outer seam weld end in a welding can body manufactured by an electric resistance mash seam welder.

It is a perspective view which shows the outline | summary of this invention. It is a figure which shows the outline | summary of the manufacturing apparatus of this invention. It is an expanded sectional view which shows the overlapping state of the metal blank immediately before welding. It is a cross-sectional photograph of the overlapping part of the seam welded part. It is a cross-sectional photograph of the overlapping portion shaped by laser light irradiation. It is sectional drawing which shows the Z-shaped guide rail which overlaps the edge part of a metal blank. It is a schematic diagram which shows the relationship between a seam welding edge part and a laser beam irradiation position. It is a schematic diagram which shows the relationship between a seam welding edge part and a laser beam irradiation angle. It is a cross-sectional photograph of the fusion | melting part obtained by laser beam irradiation to a metal blank metal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal electrode roll 2 External electrode roll 3, 4-wire electrode 5 Mandrel 6 Repair coating apparatus 10 Can body preform 10a Outer edge part 10b Inner edge part 10c Overlapping part 12 Welding can body 13 Seam welding line 20 Laser Light irradiation mechanism 21 Laser oscillator 22 Reflection mirror 23 Condensing lens 30 Seam welding line detector 31 Welding can body detector B Seam welding part B0 Welding line Be Seam welding end L Laser light C1 Seam welding outer end C2 Seam welding inner End C11 Seam welding outer end (immediately after seam welding)
D Laser irradiation completion part ho Step difference h Melting depth w Melting width

Claims (7)

Overlapping edge portions of metal blanks are overlapped to form a can body molded body having an overlapped portion, wire electrodes are brought into contact with both surfaces of the overlapped portion, and electric resistance mash seam welding is performed to weld a can. In the method of manufacturing a welded can body for manufacturing a body,
Welding characterized in that the outer end portion is shaped by irradiating a laser beam along the outer end portion of the seam welded portion of the welding can body after mash seam welding and melting the outer end portion. A method for manufacturing a can body.   The said laser beam is irradiated during the conveyance movement between a mash seam welding process and the process of giving the corrosion prevention coating to the said seam welding part, The manufacture of the welding can body of Claim 1 characterized by the above-mentioned. Method. It is manufactured by superposing the opposing edge portions of the metal blank to form a can body molded body having an overlapped portion, bringing the line electrodes into contact with both surfaces of the overlapped portion, and performing electric resistance mash seam welding. In the welding can body
A welding can body characterized in that after the seam welding process, laser light is irradiated along the outer end portion of the seam welded portion, and the outer end portion is melted to form the outer end portion. .   The dimension of the outer end melted by the laser light irradiation is a melting depth of 50% or more of the step of the outer end and a melting width of 50% or more of the step of the outer end. The welding can body according to claim 3, wherein Overlapping edge portions of metal blanks are overlapped to form a can body molded body having an overlapped portion, wire electrodes are brought into contact with both surfaces of the overlapped portion, and electric resistance mash seam welding is performed to weld a can. In the welding can barrel manufacturing apparatus for manufacturing the barrel,
Between the mash seam welding mechanism and the coating mechanism that coats the seam weld to prevent corrosion, the laser beam irradiation mechanism that irradiates the laser beam to the seam weld end has a laser oscillator and a laser focusing optical mechanism. A welding can barrel manufacturing apparatus characterized by the above.   The laser light irradiation mechanism includes a sensor for detecting a passing position of the welding can body, and includes a mechanism for controlling start and stop of oscillation of the laser oscillator based on a detection signal of the sensor. The apparatus for manufacturing a welded can body according to claim 5.   6. The laser light irradiation mechanism includes a sensor for detecting a seam weld line position of mash seam welding, and a control mechanism for controlling a laser light irradiation position by a seam position detection signal from the sensor. An apparatus for manufacturing a welded can body as described in 1.