BACKGROUND ART In general, a beverage can is wide-spreadly used since it can store the beverages for a long period of time and provide an easy handling thereof. The beverage can includes a cylindrical body made of metal such as steel or non-ferrous metal such as aluminum, and an aluminum end seamed with an upper portion of the cylindrical body.

The aluminum end has a score line for allowing a portion of the end to be easily torn to free an opening through which the beverage is poured out. A tab is provided in the end to push the score line to open the can.

Accordingly, in order to enjoy the beverage contained within the can, the tab has to be lifted off the end to tear the score line formed in the end. With this manner that the beverage contained within the can is dispensed through the opening defined with the score line torn by the tab, the consumer can simply enjoy the beverage.

The present invention relates to a method of manufacturing a tab attached to the can end to provide the consumer with convenience, on which a commercial indicium or a commercial design is applied for an aesthetic purpose, wherein an expensive aluminum material of which the tab is normally made is replaced with a cheap steel material which can increase the quality of a printed commercial indicium due to its remarkable coloration property, thereby reducing the manufacturing cost and enabling a higher quality of a steel design tab. Hereinbelow, the commercial indicium applied on the tab includes a logo of a manufacturer of the beverage can, an image, advertising copies, characters such as an animation character for promoting sales of the goods or a caricature of a famous person, an image of fruit in case that the can contains a fruit beverage, a logo and a mascot for a championship game, and logos and trademarks for private companies.

Meanwhile, although decorating the tab or applying the commercial design on the tab by using a laser etching has been proposed, it is not appropriate for a mass production due to a reduced productivity caused by the laser etching.

In order to solve those problems, the Applicant suggested in Korean Patent Laid-Open Publication No. 2000-72711 filed on September 21,2000, a method and an apparatus for attaching a sticker having commercial indicium to a beverage can. The method comprises the steps of forming a tab of a predetermined shape; transferring the tabs to the next step, arranging the formed tabs in three rows on a moving conveyor belt; attaching stickers to top surfaces of the tabs which are arranged in three rows, by using rotating rollers for attaching the sticker, respectively; determining if the sticker has been exactly positioned on the tab; and stacking the tab on an can end supplied from other place.

In the method disclosed in the application, although the customer interest on the

product or a whole appearance of the product can be enhanced by attaching the sticker having thereon characters and marks indicating the kinds of products to the top surface of the tab during the manufacturing process of the can, it is easy for the characters or the marks to be lost during dealing with the can or the transferring process and to be changed in color after a long period of time has been elapsed, since they exist in the form of sticker.

The Applicant also suggested in Korean Patent application No. 10-2001-8020 filed on February 17,2001, which discloses a method of manufacturing an aluminum design tab attached to a beverage can. The method comprises the steps of painting an aluminum coil for the tab with desired color, printing the commercial indicium of characters, images and letters represented with various colors on the painted surface of the coil for the tab, varnishing the printed surface of the coil for the tab, performing a pitch-align to ensure that the commercial indicium is located in an exact location within the tab which will be made, forming the aligned coil into a tab by a conversion press, and stacking the newly made tab on a center of a shell supplied from other place.

Although the method of manufacturing the aluminum tab does not require a separate anticorrosive process since the tab is made aluminum, in order to use steel in stead of aluminum as a material of which the tab is made, appropriate steel material and hence an anticorrosive process are necessary.

DISCLOSURE OF THE INVENTION It is, therefore, a primary object of the invention to provide a method of making a design tab for a beverage can, wherein printing a commercial indicium or a commercial design on a surface of a steel coil for the tab whose curling portion is

blocked is performed and then a varnishing process is performed before a tab forming process by using a conversion press, thereby increasing a quality of the printed commercial indicium, and anticorrosive processes for preventing the steel material from becoming rusty are added to allow replacing the aluminum for the tab with a cheap steel material which can increase the quality of the printed indicium due to its remarkable coloration property, thereby reducing a manufacturing cost.

In order to achieve the object, the present invention provides a method of making a design tab with a commercial indicium for a beverage can provided with a cylindrical body containing the beverage, an end seamed with an upper portion of the cylindrical body and having a score line for allowing a portion of the end to be easily torn to free an opening through which the beverage is dispensed out, the method comprising the steps of : painting a steel coil for the tab with a desired color; printing the commercial indicium of characters, images and letters represented with various kinds of colors on the painted surface of the steel coil for the tab; varnishing the printed surface of the steel coil for the tab; performing a pitch-align to ensure that the commercial indicium is located in an exact location within the tab which will be made; forming the pitch-aligned steel coil into a tab by a conversion press; applying a quick-drying paint on a cut cross-section of the steel coil for the tab as an anticorrosive; stacking the tab on a center of a shell supplied from other place; and applying a quick-drying paint on portions of the tab at which the tab is separated from a skeleton.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and features of the instant invention will become apparent from the following description of preferred embodiments taken in conjunction

with the accompanying drawing, in which: Fig. 1 shows a block diagram of the inventive method for making a steel design tab of a beverage can.

MODES OF CARRYING OUT THE INVENTION Hereinbelow, preferred embodiment of the inventive method of manufacturing a steel design tab of a beverage can is described with reference to an accompanying drawing.

Fig. 1 shows a block diagram of the inventive method for manufacturing a steel design tab of a beverage can.

In order to increase the quality of the goods and a workability in forming a curled steel design tab on which commercial indicia, e. g., a logo of a manufacturer of the beverage can and various characters such as an animation character are printed, the present invention exemplifies a method wherein printing such commercial indicium on a surface of a coil (a curl portion not subjected to a punching in the tab forming process) is performed before forming the tab using a conversion press. That is, since time interval between forming the tab and then attaching the tab to the shell is no more than 0.1 second, during manufacturing a complete can end by forming the tab and then attaching the tab to the shell in the conversion press, it is somewhat impossible to put the printing process between forming the tab and attaching the tab to a shell; and, even if the printing process is put between those processes, only a reduced productivity will be expected. Accordingly, in the present invention, printing the commercial indicium on a steel design tab is previously preformed through processes shown in Fig. 1.

First, a steel coil for a steel tab starts to be slowly unrolled from a steel coil

wound into a form of roll; and then both surfaces of the steel coil are painted in a desired color as a next step.

Next, printing the commercial indicium with various kinds of colors on the painted coil for the steel tab is performed. At the moment, for printing the commercial indicium, various printing rollers are arranged in multi-steps manner. An oil-based ink or a UV ink is continuously supplied to a surface of the roller from an ink reservoir.

Accordingly, the oil-based ink or the UV ink is applied on both surfaces of the steel coil, when the steel coil painted with various kinds of colors passes through the rollers arranged in multiple steps.

Next, after the printing step where the surfaces of the steel coil for the tab are printed with various kinds of colors, the steel coil is subjected to a varnishing process for protecting the printed commercial indicium thereon. For the varnishing process, preferably, a W varnish or an oil-based varnish is used as coating material by using a curing device using an ultra violet ray. In the varnishing process, the coating is performed in such a manner that both surfaces of the steel coil for the tab are coated by various kinds rollers arranged in a multi-steps manner, with coating material such as the UV varnish or the oil-based varnish continuously supplied to the surface of the roller from a varnish reservoir.

After the varnishing process, a pitch-align process is performed for ensuring an exact pitch alignment during punching the tab. The steel coil for the tab exactly aligned through the pitch-align process enters into a tab-forming process by a pitch transfer device, to be formed into the tab of a predetermined shape by a conversion press.

Next, in order to prevent a cut cross-section of a peripheral of the tab cut into the predetermined shape from becoming rusty, an anticorrosive process is performed on

the cut cross-section by using, e. g., a spray. Preferably, a quick-drying paint is sprayed as the anticorrosive.

The steel tab with the commercial indicium formed by the press is attached to the shell supplied from other place and is packed as a finished product. Then, it is supplied to a manufacturing line for the beverage cans.

Finally, for portions of the tab at which the tab is separated from the skeleton in a stacking process, an anticorrosive, e. g., a quick-drying paint is sprayed on those portions to protect them.

The method for manufacturing the tab with the commercial indicium constructed in this manner can be summarized as follows: That is, the method of manufacturing a curled steel design tab includes the steps of : painting the steel coil for the tab with desired colors; printing a commercial indicium, e. g., a character, an image or letters, with various kinds of colors on the painted surface of the steel coil for the tab; varnishing the surface of the steel coil for the tab having been printed; performing a pitch-align to exactly locate the steel coil for the tab by adjusting the location of the steel coil for the tab; forming the pitch-aligned steel coil into a tab by a conversion press; applying a quick-drying paint on a cut cross- section of the steel coil for the tab as an anticorrosive; stacking the tab on a center of the shell supplied from other place; and applying a quick-drying paint on portions of the tab at which the tab is separated from a skeleton. With the series of processes like these, a center portion of the tab enclosed at its head portion has the commercial indicium such as characters, images, a logo and a trademark of a company exactly printed thereon, so that the customers interest in the product having the steel design tab can be increased.

Further, adding the anticorrosive process for preventing the steel material from becoming rusty enables replacing the aluminum for the tab with a cheap steel material

which can increase the quality of the printed indicium due to its remarkable coloration property, thereby reducing a manufacturing cost.

The present invention of a method of manufacturing a steel design tab of a beverage can, wherein a steel coil for the tab is initially painted and then subjected to a varnishing process through printing the commercial indicium on the tab before a tab forming process, and the steel coil enters into the tab forming process by using a pitch- align device, has advantage that the commercial indicium can be properly printed on the curled surface of the tab. Further, since the steel portion is completely protected by the anticorrosive processes, the expensive aluminum material can be replaced with the cheap steel material which can increase the quality of the printed indicium due to its remarkable coloration property, thereby reducing the manufacturing cost and enabling a higher quality of a steel design tab.

Although the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.