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KR-20260063914-A - Method for effectively handling the discharge of defective paper from an offset printing press

KR20260063914AKR 20260063914 AKR20260063914 AKR 20260063914AKR-20260063914-A

Abstract

The present invention relates to a method for processing defective items in an offset printing die-cutting machine with an improved rejector function, which enables cost reduction by significantly reducing the defect rate through the development of a dedicated rejector controller and setting the 'length equal division processing' option to On to reduce the number of defective items ejected and improve recognition errors. That is, in a method for processing defective output of an offset printing die-cutting machine comprising: a camera shooting unit (1); a product inspection unit (2) for determining whether there is a defect based on data transmitted from the camera shooting unit; a rejecter-dedicated controller (defective product location calculator) (3) for transmitting a gate operation signal when a defect signal is received from the inspection unit; and a rejecter (4) for selecting and discharging defective paper when a gate operation signal is received from the rejecter-dedicated controller (defective product location calculator) (3), A process of photographing the surface of the paper in the above camera shooting unit (1) and transmitting the image to an inspection device; A process of transmitting a defect signal to a rejecter-dedicated controller (3) when a defect is determined by the above-mentioned inspector (2); When a defect signal is transmitted to the rejecter-dedicated controller (3), the product detection sensor (41) of the rejecter (4) counts the number of paper sheets; When the number of papers corresponding to the distance between the product detection sensors (41) in the above inspection device (2) is counted from the product detection sensors (41), the process of determining the corresponding papers as defective papers in the rejector-dedicated controller (3); A process for determining whether the length of a fault signal is less than or equal to a certain value; When the length of the defective signal is less than or equal to a certain value, the rejecter-dedicated controller (3) recognizes the defective paper as one sheet even if two sheets of paper are detected while the defective signal is On; When the length of the defective signal exceeds a certain value, the rejecter-dedicated controller (3) recognizes the number of defective papers as equal to the number of papers detected during the defective signal On period; The process is characterized by discharging defective paper starting from the paper identified as defective paper by the rejecter-dedicated controller (3), and discharging from the rejecter (4) the number of sheets recognized as defective paper in the previous process plus one additional discharge sheet.

Inventors

  • 한재호

Assignees

  • 주식회사 한국팩키지

Dates

Publication Date
20260507
Application Date
20241031

Claims (7)

  1. A method for processing defective output of an offset printing die-cutting machine comprising: a camera shooting unit (1); a product inspection unit (2) for determining whether there is a defect based on data transmitted from the camera shooting unit; a rejecter-dedicated controller (defective product location calculator) (3) for transmitting a gate operation signal when a defect signal is received from the inspection unit; and a rejecter (4) for selecting and discharging defective paper when a gate operation signal is received from the rejecter-dedicated controller (defective product location calculator) (3). A process of photographing the surface of the paper in the above camera shooting unit (1) and transmitting the image to an inspection device; A process of transmitting a defect signal to a rejecter-dedicated controller (3) when a defect is determined by the above-mentioned inspector (2); When a defect signal is transmitted to the rejecter-dedicated controller (3), the product detection sensor (41) of the rejecter (4) counts the number of paper sheets; When the number of papers corresponding to the distance between the product detection sensors (41) in the above inspection device (2) is counted from the product detection sensors (41), the process of determining the corresponding papers as defective papers in the rejector-dedicated controller (3); A process for determining whether the length of a fault signal is less than or equal to a certain value; When the length of the defective signal is less than or equal to a certain value, the rejecter-dedicated controller (3) recognizes the defective paper as one sheet even if two sheets of paper are detected while the defective signal is On; When the length of the defective signal exceeds a certain value, the rejecter-dedicated controller (3) recognizes the number of defective papers as equal to the number of papers detected during the defective signal On period; A method for processing defective paper discharge of an offset printing die-cutting machine, characterized by the process of discharging defective paper starting from the paper identified as defective paper by a rejecter-dedicated controller (3), and discharging from the rejecter (4) the number of sheets recognized as defective paper in the previous process plus one additional discharge sheet.
  2. In Article 1, A method for processing defective output of an offset printing die cutter, characterized in that, in the process of determining whether the length of a defective signal is less than or equal to a certain value, the length of the defective signal is determined to be less than or equal to the time taken to travel half the length of one sheet of paper at the lowest printing speed.
  3. In Article 1, A method for processing defective output of an offset printing die cutter, characterized in that, in the process of determining whether the length of a defective signal exceeds a certain value, it is determined whether the length of the defective signal exceeds the time required to travel half the length of one sheet of paper at the lowest printing speed.
  4. In Paragraph 2 or 3, A defect ejection processing method for an offset printing die cutter, characterized in that the time taken to cover half the length of one sheet of paper at the lowest printing speed for the length of the defect signal is 32 to 52 ms.
  5. In Article 1, A method for discharging defective paper from an offset printing die-cutting machine, characterized in that a rejecter-dedicated controller (3) causes the gate (42) of the rejecter (4) to operate to discharge defective paper, and when a defective product arrives at the gate (42) of the rejecter (4), the rejecter (4) discharges the defective paper using an air cylinder.
  6. In Article 1, A method for discharging defective parts from an offset printing die-cutting machine, characterized by using a rejecter-only controller (3) with a response speed of 0.4 ms or less instead of a drive unit controller, and using a 'length equal division processing On' method instead of a 'length equal division processing Off' method.
  7. In Article 1, A method for discharging defective paper from an offset printing die-cutting machine, characterized in that the above-mentioned inspection device (2) determines whether the product is good or bad based on the captured image, and if it is defective, transmits a defective signal to a rejecter-dedicated controller (3) via a relay, and the rejecter-dedicated controller (3) identifies the location of the defective product and calculates the quantity of defective products, and then operates a solenoid valve (32) for gate driving, thereby discharging defective paper through a rejecter (4) whenever the gate (42) opens.

Description

Method for effectively handling the discharge of defective paper from an offset printing die cutter The present invention relates to a method for processing defective items in an offset printing die-cutting machine with an improved rejector function, which enables cost reduction by significantly reducing the defect rate through the development of a dedicated rejector controller and setting the ‘equal length division processing’ option to On to reduce the number of defective items ejected and improve recognition errors. In other words, although the length equal division processing method in conventional printing die-cutting machines has the advantage of reducing waste caused by errors in recognizing defective products, there was a problem in that defect ejection was not properly performed when the printing speed exceeded a certain level due to the slow response speed of the drive unit controller. However, to solve this problem, the present invention uses a rejecter controller with a response speed of 0.4ms or less instead of a drive unit controller, thereby enabling smooth defect ejection even at printing speeds exceeding a certain level even when using the length equal division processing method. Furthermore, if the defect signal is below a certain level and the defective part is recognized as short, the defective part is programmed to be recognized as one sheet and additional ejection is also recognized as one sheet, thereby reducing the number of defective sheets ejected from up to six regardless of defects in the past to only two, thereby significantly reducing manufacturing costs. An offset printing die-cutting machine is a machine that cuts and shapes an image printed on a material such as paper or cardboard into a specific shape. It is mainly used in the packaging industry and is used for the production of product packaging, labels, catalogs, book covers, etc. Offset printing is a method suitable for mass production because it enables high-quality image reproduction. An offset printing die-cutting machine can be seen as having three functions: printing, die-cutting, and packaging production. The printing function uses offset printing technology to print a desired image on paper or cardboard, in which ink is applied to a printing plate and then transferred to the paper through a rubber blanket. The die-cutting function serves to cut printed paper into a desired shape, which allows it to be formed into packaging boxes, labels, etc. The packaging manufacturing function is responsible for the post-processing of folding and bonding printed and die-cut materials to protect or package products. The operating principle of an offset printing die-cutting machine is broadly divided into a printing process and a die-cutting process. The printing process involves pre-engraving an image onto a printing plate. At this stage, the plate is divided into parts that absorb ink and water. Since the parts that absorb water do not receive ink, and ink is applied only to the parts containing the image, the printed plate transfers the image onto a rubber blanket. This blanket then goes through a process of printing the image onto paper or cardboard. The reason this method is called "offset" is that the ink is not transferred directly from the printing plate to the paper but passes through a rubber blanket in between. The die-cutting process involves cutting and folding printed paper into desired shapes using pre-designed molds after printing is complete. These molds are designed with high precision to produce a wide variety of product forms, and can be used to shape packaging boxes, labels, and other printed materials. FIG. 1 is a system configuration diagram of an offset printing die-cutting machine, and FIG. 2 is a system configuration diagram illustrating the internal structure of an offset printing die-cutting machine in more detail, A conventional offset printing die-cutting machine comprises a camera unit (100); an inspector (200) for determining whether there is a defect based on data transmitted from the camera unit; a driving unit controller (defective product location calculator) (300) for transmitting a gate operation signal when a defect signal is received from the inspector; and a rejecter (400) for selecting and discharging defective paper when a gate operation signal is received from the driving unit controller (defective product location calculator). The above camera shooting unit (100) is composed of an inner inspection camera for shooting the inner surface of the paper and a printing surface (outer surface) inspection camera for shooting the outer surface of the paper, and immediately transmits the shooting data to the inspection device (200) after shooting the printing surface (outer surface) and the inner inspection camera. In the above inspection device (200), when a defect is determined, a defect signal is transmitted to the drive unit controller after 1.5m from the inner inspection camera, and the drive