Method for producing a balance correction sheet for die-cutting machines

Abstract

[0036] To provide a method for easily producing a balance correction sheet capable of eliminating individual variations in pressing force inherent in a die cutting machine. A balance correction die (D) having a plurality of regularly arranged cutting blades is mounted in a die cutting machine, and a test paperboard is placed on a cutting plate. A laminated sheet, which is peelably laminated and has substantially the same outer shape as the test paperboard, is disposed either on the reverse side of the balance correction die or the cutting plate. The method includes a step of gradually increasing the pressing force of the die cutting machine until cut portions are formed in the test paperboard, and a step of sequentially peeling off, one by one, the regions of the laminated sheet (F) corresponding to the cut portions in the test paperboard under the same pressing force until no cut portions are formed in the test paperboard. These steps are repeated until all cutting blades simultaneously cut through the test paperboard. Representative [FIG. 4]

Description

METHOD FOR PRODUCING A BALANCE CORRECTION SHEET FOR DIE-CUTTING MACHINES

[0001] The present invention relates to a method for producing a balance correction sheet used in die-cutting machines, which are employed for die-cutting sheets to form external shapes of paper containers, corrugated cardboard, or for cutting resin plates or films.

[0002] Paper containers, also referred to as packaging containers or paper boxes, are formed by die-cutting and folding paper, corrugated cardboard, coated paper, resin materials, or composite sheets made of a combination of multiple papers, or paper and resin or metal, and bonding the folded parts. Paper containers are lightweight, easy to carry, and widely used across many industrial fields.

[0003] In a known die-cutting machine, a die used for cutting the sheet into a paper container shape is produced by laser processing a veneer board according to the contour of the container and the folding lines. The die includes through-grooves for embedding cutting blades and creasing members. The creasing members are configured to protrude downward to a lesser extent than the cutting blades. During cutting and creasing, rubber members arranged on the die press the sheet to prevent movement. The die performs cutting while simultaneously forming fold lines. The counterpart to the die, called a counter plate or base plate, is made of synthetic resin such as metal, ABS, PBT, PPS, or phenolic resin. It is formed from sheet-like, plate-like, or film-like substrates and machined using NC machines based on CAD data for the die. The machining forms grooves corresponding to the creasing members and cuts out areas to match the outer contour where the cutting blades contact (see DRAWING. 1). Alternatively, flat cutting plates without grooves may be used.

[0004] As shown in DRAWING. 1, the die is mounted on the upper platen of the die-cutting machine, while the counter plate is affixed to the cutting plate and placed below the die to receive the blade edge. The cutting plate is mounted to the lower platen (not shown), typically using a chase frame, and positioned to correspond to the die on the upper platen. To perform the die-cutting, the sheet is inserted between the die and the cutting plate, the lower platen is moved upward and then downward, executing the cutting process. The cutting blade forms the shape of the container while the creasing member and the groove on the counter plate create fold lines. The result is a blank, which can be folded and glued along the fold lines to form a container. In addition to the configuration described above, other configurations exist (not shown), where perforation blades create zipper lines in the sheet during the die-cutting and creasing process. While DRAWING. 1 shows the die on the upper side and the cutting plate on the lower side, a reverse configuration is also possible.

[0005] Although a single blank may be formed per stroke of the die-cutting machine, it is preferable for productivity to form multiple blanks simultaneously four blanks per stroke.

[0006] To uniformly cut multiple blanks, it is necessary that the pressing force from the die be applied evenly across the sheet. However, uneven pressure may occur due to maintenance issues or aging of the die-cutting machine. Various measures have been taken to reduce such pressure irregularities and achieve uniform cutting.

[0007] The present inventors disclosed in Patent Document 1 a balance correction sheet made from a laminated sheet structure of peelable sheets to compensate for pressure imbalance caused by distortion or wear in the driving components of the die-cutting machine. The laminated sheet features areas with shallow cuts where pressure is weak and deeper cuts where pressure is strong, and is partially removed in accordance with cut depth. This results in increased thickness in low-pressure areas and reduced thickness in high-pressure areas, thereby equalizing the applied pressure.

[0008] Japanese Patent No. 5197870

[0009] However, the method of creating the balance correction sheet described above is complicated due to the need to half-cut the laminated sheets and selectively remove different numbers of layers according to local pressure variations. As a result, implementing this method has been difficult. Therefore, the object of the present invention is to provide an easy method for producing a balance correction sheet capable of eliminating pressure unevenness in a die-cutting machine.

[0010]

[0011] The method of producing a balance correction sheet for a die-cutting machine according to the present invention is characterized in that: a die having cutting blades and a cutting plate positioned to face the die are arranged to form blanks by cutting sheets; to resolve individual pressure imbalance specific to the machine and apply uniform pressure, a balance correction test die with regularly arranged blades is mounted on the die-cutting machine; test cardboard is placed on the cutting plate to identify pressure variations; a laminated sheet stack, peelably layered and having an outer shape substantially identical to the test cardboard, is positioned on the back side of the cutting plate or under the test die. The method involves incrementally increasing the pressing force of the machine until partial cuts appear on the test cardboard. Then, for each partially cut area, the corresponding region of the laminated sheet is peeled off one sheet at a time, placing new test cardboard with each peel, and repeating until all blades simultaneously cut through the test cardboard. This results in a balance correction sheet with a thickness profile adapted to the pressure imbalance of the machine. When the laminated sheet is installed on the upper platen side, it is sandwiched between a protective plate mounted on the rear plate of the chase holding the balance test die and a cover sheet made of resin film or thin metal. This configuration prevents shifting and damage of the laminated sheet. The cover sheet also facilitates easy removal and future maintenance, such as re-adjusting the balance after long-term use.

[0012] To ensure correct removal of sheet areas corresponding to cut sections of the test cardboard, markings are made around those regions and identifiers are applied to distinguish them from other parts. Identifiers may include color coding or other visual marks applied to each sheet of the laminated structure.

[0013] Furthermore, if pressure imbalance reoccurs over time in a die-cutting machine already fitted with a balance correction sheet created by this method, additional sheets may be overlaid and peelably applied to the existing correction sheet, reflecting prior pressure imbalance and enabling rapid re-balancing without producing a new sheet from scratch.Effects of the Invention

[0014] According to the present invention, unlike conventional methods requiring partial cutting of layers based on cut depth, the method relies on a simple and repeatable operation of peeling individual sheets from the top surface of the laminated sheet, allowing rapid creation of a balance correction sheet. This enables efficient correction of pressure imbalance in the die-cutting machine. By applying identifiers to the laminated sheet or individual layers, missed removals can be prevented and pressure imbalance can be visualized. Moreover, since the balance correction sheet is composed of peelable laminated layers, if pressure imbalance arises due to aging, new laminated sheets can be simply overlaid on the existing one, allowing the reuse of prior correction profiles and significantly reducing time and steps for maintenance compared to creating a new correction sheet.

[0015] is a schematic diagram illustrating a general die-cutting machine, including the embodiment of the present invention.is a diagram illustrating the laminated sheet in the present embodiment.is a diagram illustrating the balance correction die in the present embodiment.is a schematic diagram illustrating the condrawinguration of the die-cutting machine during preparation for balance correction sheet production in the present embodiment.is a schematic diagram illustrating the die-cutting machine when preparation for producing the balance correction sheet is complete in the present embodiment.is a diagram illustrating part of the process of creating the balance correction sheet in the present embodiment.is a diagram illustrating the test cardboard used in the present embodiment.is another diagram illustrating the test cardboard used in the present embodiment.is a diagram illustrating the positional relationship between the laminated sheet and the test cardboard during the balance correction sheet creation process.is a diagram illustrating the laminated sheet during the balance correction sheet creation process.is a diagram illustrating the laminated sheet during the balance correction sheet creation process.is an image illustrating the step of removing part of the laminated sheet during the creation of the balance correction sheet in the present embodiment.is an image illustrating the state of the test cardboard upon completion of the balance correction sheet in the present embodiment.is a diagram illustrating another example of a balance correction die, different from the one in the aforementioned embodiment.Modes for Carrying Out the Invention

[0016] Hereinafter, specific embodiments for implementing the present invention will be described in detail with reference to the drawings. (Die-Cutting Machine) DRAWING. 1 is a schematic diagram showing a known die-cutting machine 1 into which the balance correction sheet S of the present embodiment is introduced. It is a cross-sectional view schematically showing the relationship between the die-cutting die 11, a sheet of paper P to be converted into a carton by die cutting, and the cutting plate 21.

[0017] The die-cutting die 11 is manufactured by forming through-grooves for a cutting blade 101 and a creasing rule 102 in a plywood board using laser or router processing, based on the blank outline and crease line layout. The cutting blade 101 and the creasing rule 102 are embedded in the respective through-grooves to form the die. In this embodiment, the die-cutting die 11 is mounted on the upper platen 10 side of the die-cutting machine 1 via a chase (frame), although other mounting configurations may also be used. The creasing rule 102 is set to have a height smaller than that of the cutting blade 101, so that the amount it protrudes downward is also smaller than the cutting blade 101. When performing die-cutting and creasing on paper P, the rubber member 103 disposed on the die-cutting die 11 holds the paper P in place while cutting and creasing are performed.

[0018] A cutting plate 21, which receives the cutting blade 101 during the die-cutting process, is disposed opposite the die-cutting die 11. Similar to the die, the cutting plate 21 is mounted to the lower platen 20 of the die-cutting machine 1 via a chase. The counter plate 22 (faceplate) attached to the cutting plate 21 is made of synthetic resin such as ABS, PBT, PPS, or phenolic resin, and consists of a board, sheet, or film. Using CAD data of the die-cutting die 11, an NC machine cuts grooves at positions corresponding to the creasing rules 102 and cuts away portions corresponding to the cutting blades 101, forming the counter plate.

[0019] A sheet of paper P is inserted between the die-cutting die 11 and the counter plate 22 of the cutting plate 21, and die-cutting is performed by raising and lowering the lower platen 20. (Method of Producing Balance Correction Sheet)

[0020] In the above-described die-cutting process, variation in pressing force applied to the paper is unavoidable. The balance correction sheet S of the present invention aims to even out such force variation and is disposed on the upper platen side (position X in DRAWING. 1) of the die-cutting die 11. The method for producing the balance correction sheet S is described below.

[0021] To produce the balance correction sheet S of the present invention, a laminated sheet F and a balance correction die D are used. DRAWING. 2 schematically shows the laminated sheet F, and DRAWING. 3 shows the balance correction die D. (Laminated Sheet)

[0022] The laminated sheet F comprises multiple peelable sheets Fa laminated in a rectangular form, as shown in DRAWING. 2(b). The laminated sheet F is made of materials such as paper, resin, metal, or composites thereof, and the sheets are peelably bonded or laminated. More specifically, suitable materials include paper, PPS, PP, polyethylene, polystyrene, PVC, PET, polyimide, acetate, acrylic, epoxy, aluminum, iron, stainless steel, or combinations thereof. The sheets Fa may have adhesive layers (rubber-based, acrylic, etc.) on at least one side or may be formed from materials that adhere via surface structure or static electricity. Each sheet Fa has a thickness of From 10 μm or more to 100 μm or less, and the laminated sheet F consists of 5 to 25 layers. Maintenance can be continued semi-permanently by starting with, for example, a 5- or 10-layer sheet and later laminating additional layers as needed. (Balance Correction Die)

[0023] The balance correction die D includes a substrate Da and cutting blades Db (Db1 for horizontal and Db2 for vertical blades) as shown in DRAWING. 3. The substrate Da is a rectangular board made of thick plywood or resin block. Through-grooves are formed at regular intervals in vertical and horizontal directions using laser processing, and the cutting blades Db1 (horizontal) and Db2 (vertical) are embedded to form a grid. DRAWING. 3(a) is a front view showing the blade side of the die D, and DRAWING. 3(b) is a side view of the same. Preferably, the area of the substrate Da is approximately equal to or slightly larger than that of the laminated sheet F. (Preparation for Producing Balance Correction Sheet)

[0024] DRAWING. 4 is a schematic perspective view of the die-cutting machine used to produce the balance correction sheet S, and DRAWING. 5 shows the state after preparation is complete. (1) The balance correction die D is mounted on the upper platen side via a chase so that the cutting blades Db face downward. (2) A backing plate W of the chase supports the non-blade side of the die D. A protective plate B and a laminated sheet F are placed on top of this backing plate W. In this embodiment, a cover sheet A made of resin or thin metal is also placed over the laminated sheet F. This arrangement prevents misalignment or damage to the laminated sheet and also prevents adhesive from contaminating other components. The removable cover sheet A facilitates future maintenance when re-balancing is needed. (3) The cutting plate 21 is attached to the lower platen 20. (4) A blade protection sheet C is placed over the cutting plate 21 to protect the cutting blades Db. (5) A test cardboard T of about 0.2 mm thickness and with an outer shape similar to the laminated sheet F is set atop the blade protection sheet C. The protective sheet C is made of PET resin film (approx. 0.2 mm thick), but thickness and material may vary as long as blade protection is ensured. (Steps for Producing Balance Correction Sheet)

[0025] With the die-cutting machine prepared as shown in DRAWING. 5, the following steps are performed:

[0026] (Step 1) Operate the machine to bring the cutting blades Db of the balance correction die D into contact with the test cardboard T (see DRAWING. 6). (Step 2) Gradually increase the pressing force to achieve a half-cut, where the blade penetrates approximately halfway into the test cardboard T (see dashed lines in DRAWING. 7). (Step 3) Further increase the pressure slightly and stop when the blade cuts through the cardboard; record the applied pressure (see DRAWING. 8).

[0027] (Step 4) Align the test cardboard T with the laminated sheet F (see DRAWING. 9(a)), and mark the area on laminated sheet F corresponding to the cut area (see DRAWING. 9(b)). The marked area M indicates regions of higher-than-average pressure. (Step 5) Cut and peel off one layer of the laminated sheet Fa in the marked area M. To prevent missing this step, identifiers (e.g., hatching, colors, symbols) may be added to marked areas (see DRAWING. 10 and DRAWING. 11).

[0028] (Step 6) Place a new test cardboard T on the cutting plate and apply the same pressure used previously to check for any cut areas.

[0029] (Step 7A) If cutting still occurs, repeat Steps 4 to 6 until no cutting is observed. (Step 7B) If no cutting occurs, slightly increase the pressure so the blade penetrates the test cardboard by 0.03 to 0.05 mm deeper than in the previous test.

[0030] (Step 8) If cutting occurs, mark the corresponding area on the laminated sheet F and peel off one layer, then repeat the test as in Step 6. (Step 9A) If cutting still occurs, repeat Step 8. (Step 9B) If no cutting occurs, again slightly increase the pressure (0.03 to 0.05 mm deeper than the previous step).

[0031] As described above, steps 7A to 9B are repeated several times, and a laminated sheet F having thickness variations corresponding to the specific unevenness in pressing force of the die cutting machine is interposed, thereby gradually increasing the pressing force of the die cutting machine 1. Eventually, the test paperboard T is completely punched through by the cutting blade Db (see DRAWING. 12). The laminated sheet F in this state serves as the balance correction sheet S corresponding to the die cutting machine 1, thereby ensuring that the pressing force applied by the die cutting machine 1 becomes uniform.

[0032] (Other Embodiments) In the embodiment described above, the balance correction die D is configured such that the cutting blades Db are arranged in a grid pattern. However, the configuration is not limited to a grid layout, and other arrangements may be employed as long as they allow for identification of punched and unpunched areas, such as the arrangement shown in DRAWING. 13. Any shape can be appropriately selected based on this requirement.

[0033] As shown in DRAWING. 13(b), the cutting blades Db may be arranged to form multiple triangles. In this case, an interval Y is provided at part of the intersection (contact) points between the blades to prevent perfect triangular cuts. This configuration introduces incisions in the test paperboard T without fully severing it, keeping it as a single connected piece. This has the beneficial effect of facilitating the marking step on the laminated sheet F to outline the positions corresponding to the punched portions, since the test paperboard does not fall apart and the work proceeds smoothly. While DRAWING. 13(b) illustrates a configuration where the interval Y is provided at part of the blade intersections, the interval Y may alternatively be provided at all blade intersections to prevent any contact.

[0034] In the present embodiment, the balance correction die D is described as being disposed on the upper platen 10 side, and the cutting plate 21 on the lower platen 20 side. However, the configuration may be reversed, with the cutting plate on the upper platen side and the balance correction die D on the lower platen side. In such a case, the laminated sheet is arranged on the rear side of the cutting plate.

[0035] As described above, according to the disclosed invention, a balance correction sheet S can be easily created without requiring special skills, simply by preparing the balance correction die D, laminated sheet F, and test paperboard T and repeating a straightforward process. This makes it possible to adjust the die cutting machine 1 to achieve uniform pressing force without variation. Explanation of Reference Signs Reference Sign Description 1 Die cutting machine 10 Upper platen 11 Die (cutting die) 101 Cutting blade 102 Creasing member 103 Rubber member 20 Lower platen 21 Cutting plate 22 Counter plate (face plate) A Cover sheet (of laminated sheet) B Protective plate C Blade protection sheet D Balance correction die Da Substrate (of balance correction die) Db Cutting blade (of balance correction die) Db1 Longitudinal blade (of balance correction die) Db2 Transverse blade (of balance correction die) F Laminated sheet Fa Sheet constituting the laminated sheet M Area of laminated sheet corresponding to punched portion of test paperboard P Sheet (paper) S Balance correction sheet T Test paperboard W Back plate of chase (frame body) Y Gap provided at intersection of cutting blades of balance correction die

Claims

1. A method for producing a balance correction sheet for a die-cutting machine, in which a cutting die and a cutting plate arranged to face each other receive cutting edges of the cutting die, and blanks are formed by punching paper sheets, the method aiming to eliminate individual variations in pressing force specific to the die-cutting machine and to apply a uniform pressing force, the method comprising: mounting a balance-correction die having a plurality of cutting edges arranged in a regular pattern on the die-cutting machine; placing a test paperboard on the cutting plate to measure variations in pressing force; placing a laminated sheet, which is peelably laminated and has substantially the same outer shape as the test paperboard, on the back side of either the balance-correction die or the cutting plate; slightly increasing the pressing force of the die-cutting machine until partially punched portions appear in the test paperboard; peeling off, one by one, the portion of the laminated sheet corresponding to the partially punched portion of the test paperboard, and for each peeling, placing a new test paperboard on the cutting plate; and repeating the process until all the cutting edges of the balance-correction die simultaneously punch through the test paperboard, thereby obtaining a balance correction sheet comprising laminated sheets of varying thicknesses corresponding to the variations in pressing force of the die-cutting machine.

2. The method for producing a balance correction sheet according to claim 1, wherein, to avoid omitting removal of the portions of the laminated sheet corresponding to the punched portions of the test paperboard, markings are provided around the periphery of said portions, and identifiers are applied to distinguish said portions from other parts.

3. The method for producing a balance correction sheet according to claim 1 or 2, wherein when the laminated sheet is placed on the upper platen side of the die-cutting machine, the laminated sheet is sandwiched between a protective plate disposed on a back plate of a chase to which the balance-correction die is fixed, and a cover sheet made of a resin film or thin metal plate.

4. The method for producing a balance correction sheet according to claim 1 or 2, wherein each sheet forming the laminated sheet is provided with an identifier for individual recognition.

5. A method for producing a balance correction sheet, wherein when variations in pressing force occur over time in the die-cutting machine to which a balance correction sheet created according to the method of claim 1 is applied, an updated laminated sheet reflecting the previous variations in pressing force of the die-cutting machine is obtained by additionally stacking and removably laminating a desired number of sheets forming the laminated sheet on the existing balance correction sheet.

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