JP2003040265A - Welding can body with code mark and method for forming the code mark - Google Patents

Abstract

[PROBLEMS] To provide a welded can body with a code mark with good production efficiency and a method for applying the code mark. SOLUTION: A code mark 5 is engraved by laser light on at least a part of a metal surface of a portion surrounded by a weld seam 4 on which a coating printing of the welding can body 1 is not performed and an elongated region 3 on both sides thereof. The code mark 5 is protectively coated with a transparent resin film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding can barrel having a code mark used for quality control and production control, and a method for forming the code mark.

[0002]

2. Description of the Related Art It is common practice to give a code mark to a product in order to distinguish the origin and manufacturing history of the product. As a marking method, a marking method using a code mark punch or a thermosetting ink is used. And U
Printing using a V (ultraviolet) curing ink or the like, or an inkjet method is generally adopted. One example thereof is described in JP-A-6-156503.

[0003] In this publication, a welding seam in which the welding can body is not painted and printed by an inkjet printing method,
Welding cans with code marks (numbers, symbols, signs, etc.) such as the date and time of can manufacturing and the name of the manufacturing line printed on a part of the long and narrow areas on both sides of the can, and a protective coating applied on top of it And its printing method are described.

[0004]

The ink used in the above-mentioned conventional ink jet printing method is a specific ink generally used for an ink jet printing apparatus using a quick-drying solvent. The ink easily causes troubles such as bleeding and ink clogging, and it is necessary to regularly clean and clean the nozzle portion. In order to prevent troubles,
Even when it is not used for a long time, it is necessary to clean and clean the nozzle. However, this kind of work
There is an inconvenience that extra time is required in addition to the production time.

Further, in the conventional ink jet printing method,
It was necessary to always prepare consumables such as ink and solvent. Furthermore, since protective coating is applied immediately after printing with an inkjet, the protective coating that can be used is limited in order to prevent ink bleeding on the printed code marks.

The present invention has been made in view of the above technical problems, and an object thereof is to provide a welded can barrel with a code mark and a method for providing the code mark with high production efficiency. is there.

[0007]

In order to solve the above-mentioned problems, the invention of claim 1 is surrounded by the weld seam of the welding can body and the long and narrow regions on both sides thereof, which are not coated and printed. In a welding can barrel having a code mark on at least a part of the metal surface within the part, the code mark is marked by irradiating the metal surface with a laser beam, and the code mark is protected by a transparent resin coating. It is a welding can body with a code mark, which is characterized by being covered.

Therefore, according to the first aspect of the present invention, at least a part of the metal surface of the weld seam, which is the unpainted portion of the welding can body, and the elongated regions on both sides of the weld seam, is irradiated with laser light. A code mark is engraved on the metal surface. Thereafter, a transparent paint is applied to the code mark or a transparent thermoplastic resin film is adhered to the code mark for protective coating, thereby improving the rust resistance of the welding can body. Further, since the code mark is formed by shaving the metal surface with the laser beam, even when the code mark is engraved on the portion where the metal surface is oxidatively discolored, the code mark becomes a bare metal color and easy to read.

According to the second aspect of the present invention, a metal plate having a surface excluding both ends for welding is coated and formed into a tubular shape, and the both ends are welded and joined, and the welding is performed. At least a part of the metal surface in the unpainted elongated area on the seam and its both sides is irradiated with laser light to engrave a code mark, and immediately after that, the area including the code mark is not coated. A method of forming a code mark is characterized in that the surface of the metal exposed portion in the area is coated with a transparent paint and then the transparent paint is dried.

Therefore, according to the second aspect of the present invention, after being welded to form the can body, the outer surface of the welded joint portion of the welded can body is transferred to the coating device for coating the transparent paint while being transported.
The code mark engraved with the laser beam is immediately coated with transparent paint by the subsequent coating device and dried, so that the protection by the protective coating is sufficient.

According to a third aspect of the present invention, a metal plate having a surface excluding both ends for welding is coated and painted, and the both ends are welded and joined together. A non-painted area including the code mark immediately after irradiating a laser beam on at least a part of the metal surface in the seam and the non-painted area on both sides of the seam. A transparent thermoplastic resin film is attached to the surface of the metal-exposed portion of the inside, and thereafter, the thermoplastic resin film is heated to be welded to the surface of the metal-exposed portion by a method of forming a code mark. is there.

Therefore, according to the third aspect of the present invention, after the can body is formed by welding, the outer surface of the welded joint portion of the weld can body is transferred to the device for adhering the transparent thermoplastic resin film. , The code mark engraved with laser light,
A transparent thermoplastic resin film is immediately applied in the subsequent device and heated and welded, so that the code mark is sufficiently protected.

Further, the invention of claim 4 is the method of forming a code mark according to claim 2 or 3, characterized in that the laser light is YAG laser light.

Therefore, in the invention of claim 4, the code mark of claim 2 or 3 is applied to the metal surface, which is a portion not subjected to coating printing, very finely using a YAG laser, and of the base material. It is engraved with a small amount of depth compared to its thickness.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a welding can body in which a code mark of the present invention is printed, and FIG. 2 is an enlarged view of a main part. In the drawing, reference numeral 1 is a welding can barrel, which has a portion 2 on which a decorative print (not shown) is applied over a wide area, an elongated narrow area 3 on which a decorative print is not applied, and a narrow width at the center of the narrow area 3. And a weld seam 4. The above-mentioned decorative printing is a case of directly printing on dozens of can body plates and a polyester which is previously subjected to gravure printing and protective coating as described in, for example, Japanese Patent No. 3054942 and Japanese Patent No. 2873746. The film may be attached to the can body coil via an adhesive.

A code mark 5 is provided on the weld seam 4. The code mark 5 in FIG. 2 is, in order from the bottom, the factory name, can manufacturing line name, (welding machine number), year, month, and year.
Indicates day, hour, and minute. For example, the first T is the Tokyo factory, 05 is the 5th line after Hai Phong, the next KDZ is April 26, 2001, and TP is 19:30. There is. In this embodiment, since the alphabet representing the last minute unit is set to be changed to another alphabet every 2 minutes, different code marks 5 are provided every 2 minutes on the welding seam 4 of the can body even with the same welding machine. It is stamped.

Of course, it may be changed in units of 1 minute, 5 minutes, or 10 minutes. Also, it is clear that there is no need to display if there is only one welding machine per can making line. It should be noted that reference numeral 6 in FIG. 1 denotes a can lid that is wound and fixed to the welded can body 1.

FIG. 3 is a diagram showing a process of forming the can body of the present invention. The welding machine 7 shown in FIG. 3 includes upper and lower electrode rolls and a wire electrode (not shown) wound around the outer periphery thereof. When the overlapped overlapped parts of the rolled can body blank pass between the wire electrodes between the upper and lower electrode rolls, a current flows between the wire electrodes so that the overlapped parts generate heat and are welded. Has become.

Reference numeral 8 denotes an inner spray device for applying a protective paint to a non-painted region (a region corresponding to the narrow region 3 where no painting is printed) on the inner surface side of the can body.
Here, a protective coating is applied to the weld seam on the inner surface side and both sides thereof.

Reference numeral 9 denotes a laser marker, which is irradiated by the laser marker 9 so that the laser beam is irradiated to at least a part of the welding seam 4 of the welding can body 1 and the narrow region 3 where no painting is printed. The mouth is located directly above the weld seam 4. Reference numeral 10 is an external spray device for applying a transparent protective coating so that laser light is printed on at least a part of the narrow region 3 of the welding can body 1 on which the decorative printing is not applied. Although not shown, the welding can body 1 is sandwiched by two endless belts so that the position of the welding seam 4 is not displaced (preferably a magnet belt is used) in the arrow direction of FIG. While being transported, the code mark 5 is engraved and the protective paint is applied. Reference numeral 11 is a drying furnace for drying the protective coating applied to the weld seam on the inner and outer surfaces of the can body and both sides thereof.

The laser marker 9 has a wavelength of 1.6.
A μm 30 W YAG (Y3Al5O12: yttrium aluminum garnet) laser is used.
More specifically, the laser marker 9 is made by Keyence L
Model D-Y9700 with D-type YAG laser marker
(Fine beam) is used.

The flow of engraving the code mark 5 in the welding can body according to the above specific example will be described. First, as the can material, an ultra-thin tin-plated steel plate (“Canlite” manufactured by Nippon Steel Corporation) having a plate thickness of 0.175 mm, a longitudinal length of 107.95 mm and a lateral length of 165.65 mm is adopted. In the ultra-thin tin-plated steel plate (not shown), 1.90 mm wide areas not provided with decorative printing are provided on both sides in the lateral direction of one surface, and further, one side of both ends in the lateral direction of the other surface is provided. Except for the width of 90 mm, an epoxy phenolic paint for the inner surface of the can or a thermoplastic resin film is applied to make a can body blank containing 190 g.

Next, the can body blank is supplied to the welding machine 7 and rounded so that the decorative printing is on the front side, so that both end edges, which are areas where the decorative printing and the inner surface paint are not applied, are on the upper side. Then, the widths of 0.5 mm at both ends are overlapped. Then, in this state, while the can body blank is being conveyed in the horizontal direction, the overlapping portion is passed between the upper and lower electrode rolls to perform electric resistance seam welding.

Further, with the overlapped portion still on the upper side,
While the can body is held in a narrow pressure by two endless belts with magnets and conveyed in the horizontal direction, the code mark 5 shown in FIG. 2 is applied from the irradiation opening of the laser marker 9 to the welding seam 4 and decorative printing on both sides thereof. At least a part of the unpainted narrow area 3 is imprinted, and then a transparent alkyd resin paint is applied from the outer surface spraying device 10 so as to completely cover the code mark 5 and the area 3 which is not decoratively printed. Spray painting, then transport the can body into the drying oven 11,
The marking is completed by drying the protective alkyd resin paint.

Next, the state in which the code mark 5 is imprinted by the laser marker 9 will be described in more detail. The portion to be engraved is a part of the portion surrounded by the welding seam 4 formed by the ultrathin tin-plated steel sheet having a plate thickness of 0.175 mm as described above and the elongated regions 3 on both sides thereof. The use condition of the laser marker 9 is scan speed 642.5.
mm (equivalent to can transport speed 80 m / min), current value 55 A, frequency 7 KHZ, work pitch 110 mm, character height 1.
The width is 0 mm, the character width is 0.6 mm, and the character pitch is 1.0 mm.

Under the above-mentioned conditions, the result of engraving the code mark 5 shows that the engraved width is 80 μm at a maximum depth of 3 μm from a 1000 times magnified photograph (not shown) of the part marked with the code mark. . Therefore, even in the case of a welded seam where a brown oxide film is generated by the heat during welding, the engraving is applied with the oxide film scraped off.
The code mark is easy to read. Further, visually uniform code marks were obtained from the code-marked characters, and there was no special problem in identifying.

Further, the code mark 5 is formed in a very small part of the area 3 which is not coated and printed, but the maximum depth is 3 μm within the range of variation in the thickness of the can material itself (about 5 μm). Even considering that the thickness of the coating printing is about 8 μm, the influence on the can strength and the can forming is hardly considered.

Therefore, according to the above-described embodiment, by engraving the code mark 5 on the welding can body 1 with the YAG laser beam, the conventionally used ink jet printing method can be abolished. Therefore, it is not necessary to prepare consumables such as ink and solvent used in the inkjet printing method. As a result, it is not necessary to clean or wash the nozzle portion for avoiding troubles such as ink bleeding or ink clogging, so that work efficiency is improved and manufacturing cost can be reduced. Further, since the trouble such as the ink clogging is eliminated, it becomes possible to engrave the code mark 5 on the welding can body 1 without maintenance. Further, the work environment can be improved by reducing the solvent.

Further, since the paint used in the protective coating is not limited as in the ink jet printing method, an inexpensive paint can be selected and the cost can be reduced. In addition, by dry protection coating, neck-in processing after engraving the code mark 5, flange processing, can lid contraction processing and can body transporting process,
Furthermore, since the metal surface is protected in the content filling process, can lid shrinking and sealing process, heat sterilization process, canned product conveying process, etc.,
Code mark 5 and area 3 without paint printing
The problem of more rust and the like disappears.

Further, since the code mark 5 is applied to the region 3 of the welding can body where the decorative printing is not applied, its reading is not influenced by the color of the decorative printing and the decorative printing effect is not diminished. . It is less likely that the color will change due to oxidation during post-processing of the can barrel, heat sterilization of canned food, and the transportation thereof, making it unreadable.

Further, since the laser light is YAG laser light, the code mark 5 can be extremely finely engraved on the metal surface. Therefore, the contours of characters and numbers are sharper and easier to read as compared with printing by the inkjet printing method.

Immediately after the welding of the welding can body 1 and immediately before the protective coating is applied to the slender region 3 including the weld seam 4 which is not subjected to the decorative printing, the laser beam is used to apply the code mark 5 in the region 3. Therefore, the engraved code mark 5 can be covered with a transparent coating film. Therefore, the rust resistance of the code mark 5 is good. Further, except for disposing the laser marker 9 between the welding machine 7 and the outer surface spraying device 10 of the welding can body production line, there is no need to change the conventional line configuration, so that the cost of equipment and the like can be reduced. it can.

Further, since the code mark 5 indicates the line name of the welding machine 7, the date when the can body was welded, and the time of 10 minutes or less, a defect was found in the welded body 1 later. In this case, it is possible to select only the can bodies that were welded at the same time that is likely to be defective and the time before and after that time, and there is no need to unnecessarily collect a large number of can bodies or canned products It takes less time and personnel.

In the above embodiment, the code mark 5
As a protection for the outside, a transparent protective paint is applied to the external spray device 10.
However, the protective coating may be applied by roll coating or by attaching a narrow transparent thermoplastic resin film. The point is that the code mark can be protected and is transparent to the outside so that the code mark can be seen from the outside.

[0035]

As described above, according to the first aspect of the invention, the code mark is engraved on the welding can body by the laser beam, and thereafter, the code mark is protectively covered with the transparent resin film.
The rust resistance of the welding can body can be improved. Further, since the code mark is formed by shaving the metal surface with the laser beam, even when the code mark is engraved on the portion where the metal surface is oxidatively discolored, the code mark becomes a bare metal color and easy to read.

According to the second aspect of the invention, the ink jet printing method used conventionally can be eliminated. Therefore, it is not necessary to prepare consumables such as ink and solvent used in the inkjet printing method. Further, since it is not necessary to perform cleaning or washing for avoiding troubles, work efficiency is improved and manufacturing cost can be reduced. Further, since the paint used in the protective coating is not limited, inexpensive paint can be selected and the cost can be reduced. Further, since the code mark is engraved with the laser beam immediately before the protective coating is applied, the code mark can be covered with the transparent coating film. Moreover, since it is not necessary to change the conventional line configuration except for disposing the laser marker between the welding device of the welding can body production line and the outer surface side protective coating device, it is possible to reduce the cost of equipment and the like. .

According to the third aspect of the invention, the rust resistance of the area where the code mark and the print coating are not applied can be sufficiently ensured. Further, since the inkjet printing method can be abolished, the same effect as in claim 2 can be obtained.

Further, according to the invention of claim 4, by irradiating the YAG laser beam to engrave the code mark, it is possible to engrave the metal surface extremely finely. Therefore, the contours of characters and numbers are sharper and easier to read as compared with printing by the inkjet printing method.

[Brief description of drawings]

FIG. 1 is a perspective view showing a welding can body having a code mark according to the present invention.

FIG. 2 is an enlarged view of a main part of the present invention.

FIG. 3 is a diagram showing a process of forming a can body of the present invention.

[Explanation of symbols]

1 ... Welding can body, 3 ... Area without decorative printing,
4 ... Weld seam, 5 ... Code mark, 7 ... Welder,
8 ... Inner spray device, 9 ... Laser marker, 1
0 ... External spray device, 11 ... Drying furnace.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B41M 5/26 B65D 25/20 Q B65D 25/20 25/34 B 25/34 B41M 5/26 S (72 ) Inventor Hidetomo Obara 5-5-1 Nishihashimoto, Sagamihara City, Kanagawa Yamato Seikan Co., Ltd. Technology Development Center F-term (reference) 2H111 HA14 HA22 HA32 3E061 AA16 AB04 AC02 BA02 BA04 DB04 3E062 AA04 AC03 DA02 DA05 JA04 JB04 JB23 JC03 JD08 4E068 AA01 AB00 AJ04 DA06 DB01

Claims (4)

[Claims] 1. A welding can body in which a code mark is attached to at least a part of a metal surface of a welding seam of the welding can body and a part surrounded by elongated areas which are not coated and printed on both sides thereof. A welded can barrel with a code mark, wherein the code mark is engraved by irradiating the metal surface with laser light, and the code mark is protectively covered with a transparent resin film. 2. A metal plate having a surface excluding both ends for welding which is coated and printed is formed into a tubular shape, and the both ends are welded and joined to each other, and the welding seam and the both sides thereof are coated and printed. At least a part of the metal surface in the unpainted area is irradiated with laser light to imprint a code mark, and immediately after that, the surface of the metal exposed part in the area not coated by painting including the code mark Is coated with a transparent paint, and then the transparent paint is dried. 3. A metal plate having a surface excluding both ends for welding which is coated and printed is formed into a tubular shape, and the both ends are welded and joined to each other, and the welding seam and both sides thereof are coated and printed. At least a part of the metal surface in the unpainted area is irradiated with laser light to imprint a code mark, and immediately after that, the surface of the metal exposed part in the area not coated by painting including the code mark A method for forming a code mark, which comprises: sticking a transparent thermoplastic resin film to the substrate, and then heating the thermoplastic resin film to weld it to the surface of the exposed metal portion. 4. The method of forming a code mark according to claim 2, wherein the laser light is YAG laser light.