OFFSET PRINTING MACHINE FOR THICK SHEET PAPERS
Technical Field
The present invention relates to an offset printing machine for thick sheet papers and, more particularly, to an off printing machine using a PS plate formed of an aluminum plate on which a film is printed in order to obtain print quality as high as photographs.
Background Art
In general, a thick sheet paper such as a corrugated cardboard is printed in such a manner that, when an ink roller coats ink on an embossed-carved protruded portion of a convex plate (resin plate or rubber plate) attached to a printing roller, the printing roller prints a figure or letter having the shape of the protruded portion on one side of the corrugated cardboard passing through a press roller. However, this method using the convex plate cannot realize printing with picture quality as high as photographs because it cannot perform dot printing. Thus, it is impossible to print various and complicated designs on a paperboard used for boxes with this method.
Accordingly, there was proposed a method by which a surface sheet is first printed using rotary printing and offset printing while transferring a thin master sheet rolled on a roll and then the printed sheet is attached onto a corrugated cardboard. This technique needs the additional process of attaching the thin surface sheet onto the corrugated cardboard and requires the separate surface sheet, to result in an increase in the manufacturing cost of packing boxes when the sheet is used for the boxes. This remarkably deteriorates competitiveness of the packing box in the market.
Meantime, according to the agricultural products standard, the width of a
sheet for a packing box holding 10 kilograms is abovel,535mm. However, the width of a printing sheet, generally used, is 1,090mm. Thus, the surface sheet of the box cannot be printed at once because the width of the packing box is wider than that of the whole uncut paper for printing. Accordingly, it is required that the surface sheet is divided into two pieces to be printed and then they are pieced together to form the box. This increases the serial process such as printing, attachment, outer line cutting, banding and iron pin fixing operations twice, considerably extending a period of time required for assembly process and remarkably decreasing working efficiency. Furthermore, it is impossible to automate the procedure of fabricating the boxes for packing agricultural products.
Disclosure of Invention
An object of the present invention is to provide an offset printing machine for thick sheet papers which is able to directly print a photograph-like clear picture on the surface of a thick sheet paper to obtain high picture quality and increase competitiveness of boxes for packing agricultural products in the market owing to a simple box printing process.
To accomplish the object of the present invention, there is provided an offset printing machine for thick sheet papers, comprising: a printing part 10 in which a PS plate 13a formed of an aluminum plate on which a film is printed is attached onto the outer surface of a printing roller 13 that comes into contact with a plurality of ink rollers 11 and water coating rollers 12 to be rolled together, and a press roller 15 is placed under a rubber roller 14 coming into contact with the printing roller 13 to be rolled together; a paper feeding part 20 in which thick sheet papers are contained in a paper feeding box 21 placed at one side of the printing part 10, the thick sheet papers being pushed by a push bar 23 to be discharged one by one through an outlet 22 at which a separating plate 22a is set; a transfer part 30 in which paper feeding rollers 31 having the press roller 15 placed between them are
placed at the side of the outlet 22 of the paper feeding box 21, a plurality of guide roller 32 are placed on the paper feeding rollers 31, and belts 31a and 32a wrap around the paper feeding rollers 31 and guide rollers, respectively; and a paper discharging part 40 in which paper discharging rollers 33 around which a belt 33a is wrapped are located at one side of the transfer part 30, and a paper storage case 41 for storing printed thick sheet papers 1 is located at one side of the paper feeding rollers.
Brief Description of the Drawings
Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 illustrates an offset printing machine according to an embodiment of the present invention; and
FIG. 2 is a perspective view of the offset printing machine according to the present invention.
Best mode for Carrying Out the Invention
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
Referring to FIGS. 1 and 2, the outer surface of a printing roller 13 comes into contact with a plurality of ink rollers 11 and water coating rollers 12 to be rolled together. The ink rollers 11 are placed on the top of the printing roller 13 and the water coating rollers 12 are located at one side of the printing roller. A PS plate 13a formed of an aluminum plate on which a film is printed is attached onto the outer surface of the printing roller 13. This PS plate 13a is formed in a manner that a photosensitive material is previously coated on the thin aluminum plate so that a
letter or figure can be engraved thereon using the film. The PS plate 13a can be kept for a long period of time without being affected by temperature and humidity and it is widely used for printing with high picture quality because its engraving process is simple. A rubber roller 14 comes into contact with the bottom of the printing roller 13 to be rolled together with the printing roller 13, and a press roller 15 is placed under the rubber roller 14, having a predetermined interval. The above- described configuration serves as a printing part 10 that transfers ink to allow the surface of a thick sheet paper 1 to be printed.
A paper feeding box 21 is placed at one side of the printing part 10, and thick sheet papers 1 are contained in the paper feeding box 21. An outlet 22 at which a separating plate 22a is set is located at the bottom of the paper feeding box 21. A push bar 23 moving horizontally by power is placed at the side opposite to the outlet 22 to push the lowest thick sheet paper 1 in the paper box 21 toward the outlet 22. Upon operation of the push bar 23, the lowest thick sheet paper 1 is pushed by the push bar 23 to be out of the box 21 through the outlet 22. Here, the separating plate 22a set at the outlet 22 controls the space of the outlet 22 to discharge the thick sheet papers one by one. The aforementioned configuration serves as a paper feeding part 20 for storing the thick sheet papers and feeding them one by one. A pair of paper feeding rollers 31 is placed at the side of the outlet 22 of the paper feeding box 21, having a predetermined interval, and the press roller 15 is located between these paper feeding rollers 31. A thick sheet paper transfer belt 31a wraps around the paper feeding rollers 31 and the press roller 15. A plurality of guide rollers 32 are placed on the paper feeding rollers 31, and a transfer belt 32a wraps around the guide rollers 32. This configuration serves as a transfer part 30 for transferring the thick sheet paper between the rubber roller 14 and the press roller 15.
Paper discharging rollers 33 around which a belt 33a is wrapped are located at one side of the transfer part 30, and a paper storage case 41 for storing printed
thick sheet papers 1 is placed at one side of the paper discharging rollers. This configuration serves as a paper discharging part 40 for transferring the printed thick sheet papers 1 to store them in the paper storage case 41.
According to the present invention constructed as above, when the lowest thick sheet paper 1 contained in the paper feeding box 21 is discharged through the outlet 22 by the operation of the push bar 23, the paper is supplied between the transfer belts 31a and 32a which respectively wrap around the paper feeding rollers 31 and the guide rollers 32, to be transferred between the rubber roller 14 and the press roller 15. Then, a picture or letter transferred to the rubber roller 14 is printed on the surface of the thick sheet paper 1 while the paper is passing between the rubber roller 14 and the press roller 15. Specifically, the ink rollers 11 coat ink on the PS plate 13a attached onto the printing roller 13 and the water coating rollers 12 put water on the PS plate 13 a. Then, the ink coated in the form of the figure or letter engraved on the PS plate 13a is transferred to the rubber roller 14, thereby being printed on the thick sheet paper 1 passing between the rubber roller 14 and the press roller 15. The printed thick sheet paper 1 passes the paper discharging rollers 33 to be stored in the paper storage case 41.
The present invention prints figures or letters on the thick sheet paper using the PS plate 13a capable of dot printing so that it can realize printing with high picture quality. Simultaneously, the surface of the thick sheet paper 1 such as corrugated cardboard is directly printed to improve convenience of printing process. Accordingly, it is possible to solve the problems in the conventional method of printing a separate surface sheet and attaching the printed surface sheet onto the thick sheet paper, to maximize printing operation efficiency.
Therefore, boxes for packing agricultural products are simply fabricated only through outer line cutting, banding and iron pin fixing processes after printing of the thick sheet paper so that the working process required for manufacturing the boxes can be minimized to rapidly form the boxes, improving competitiveness of
the packing boxes in the market.
Moreover, printing operation is not affected by the size of the thick sheet paper because it is directly carried out on the surface of the thick sheet paper, resulting in improvement in working efficiency. Furthermore, the entire process including supply, transfer, printing and storage of the thick sheet paper is automatically performed to enable realization of factory automation.
Industrial applicability
As described above, the present invention directly prints figures or letters on the surface of the thick sheet paper through the offset printing technique using the PS plate capable of dot printing to realize printing with picture quality as high as photographs. In addition, the printing operation can be simply carried out without being affected by the size of the paper, and the working process required for fabricating packing boxes is minimized to realize easy and simple manufacturing of boxes, improving competitiveness of the boxes for packing agricultural products in the market.