Counter-guard

Abstract

Counter guard with holding means designed to hold the counter-guard plate on a counter-pressure cylinder of a punching device during use, wherein the counter-guard has a flexible, tensile-resistant base plate made of a first material, as well as a protective layer which, in use, forms the radially outer surface of the counter-guard and consists of a second material that is softer than the first material, characterized by that the protective layer consists of a rubber-elastic deformable material.

Description

[0001] The invention relates to a counter-guard plate, as is known from practice and used in punching devices. The known counter-guard plate has holding means which are designed to hold the counter-guard plate on an impression cylinder of a punching device during use. The holding means can, for example, be designed such that the counter-guard plate is ferromagnetic and is magnetically held on the impression cylinder, or the holding means can, for example, be designed as rails which are received in corresponding grooves in the impression cylinder so that the counter-guard plate can be clamped onto the impression cylinder. It is also known from practice to fix counter-guard plates using double-sided adhesive tape or adhesive, in particular spray adhesive.

[0002] The known counterguard plate also features a flexible, tensile-resistant base plate made of a first material. The flexibility of the base plate allows it to be adapted to the respective diameter of the impression cylinder, allowing the counterguard plate to be mounted on the impression cylinder without play. The tensile strength ensures that the base plate is not stretchable and its secure hold on the impression cylinder is guaranteed. For example, it is known in practice to use a thin steel sheet as a base plate.

[0003] Furthermore, the known counter-shield plate has a protective layer which, during use, forms the radially outer surface of the counter-shield plate and consists of a second material that is softer than the first material. "Softer" in this context means that the protective layer offers less resistance than the base plate to the penetration of a foreign body. Such foreign bodies, during operation of the punching device, are the punching lines or creasing lines of a punching or creasing plate of the punching device. Such a plate is clamped, for example, onto a rubber blanket cylinder or magnetic cylinder, and the material web to be punched or creasing is guided between the rotating rubber blanket cylinder or magnetic cylinder and the counter-rotating impression cylinder.This proposal specifically concerns the processing of paper webs or sheets, so that paper will always be referred to below as the material to be punched. The cutting-edge punching lines completely penetrate the paper to be punched and penetrate into the protective layer of the counter-guard plate. In practice, the penetration depth can be adjusted so that the punching lines extend, if possible, through the entire thickness of the protective layer and penetrate into the protective layer as far as the base plate of the counter-guard plate, in order to ensure reliable and complete severance of the paper. The bead-like creasing lines deform the paper and, together with the paper, penetrate into the protective layer of the counter-guard plate without severing the paper.

[0004] The materials used for the protective layer must meet different requirements. During punching, a protective layer material that is too hard leads to premature wear of the punching lines, as the cutting-like tips of the punching lines become blunt prematurely. During creasing, a protective layer material that is too hard leads to pressure that the creasing lines exert on the paper and is damaging to the paper. This can lead to the paper breaking when the sheet of paper is later folded along the crease lines. If the protective layer material is too soft, the counterpressure for the punching and creasing lines is too low, meaning that reliable cutting of the paper during punching and the creation of a sufficiently sharply contoured groove embossed into the paper during creasing cannot be guaranteed. In addition, it is fundamentally necessary to adjust the creasing line to the height of the paper or sheet.of the paper sheet in order to create sufficiently functional fold lines. It is therefore known to use counter-guard plates with differently designed protective layers for punching and creasing.

[0005] The invention is based on the object of improving a generic counter-guard plate in such a way that it can be used both for punching and for grooving and enables punching and grooving in a single operation.

[0006] Features of the invention are defined in claims 1 and 8. Further advantageous aspects, details, and embodiments of the invention emerge from the dependent claims and the description.

[0007] According to a first aspect of the invention, a counter-guard plate is provided, comprising holding means which are adapted to hold the counter-guard plate on an impression cylinder of a punching device during use, wherein the counter-guard plate comprises a flexible, tensile-resistant base plate made of a first material, and a protective layer which, during use, forms the radially outer surface of the counter-guard plate and consists of a second material which is softer than the first material, wherein the protective layer consists of a rubber-elastic deformable material.

[0008] In other words, the invention proposes that the protective layer be made of a rubber-elastic, deformable material. Firstly, such a material exhibits high restoring forces, which is particularly advantageous when setting up the punching device. If the position of the punching or creasing plate on its cylinder still needs to be slightly adjusted after initial test runs, the rubber-elastic, deformable material does not exert any lateral forces on the punching or creasing lines penetrating the protective layer, which would lead to undesirable warping of the paper. This applies in particular to the creasing lines, whose position, due to their width, may partially overlap with the original position during the initial test runs after an adjustment of the creasing plate.If indentations in the protective layer of the counter-guard plate have already been created as a result of plastic, permanent deformation during the initial test runs, these indentations can lead to undesirable movement of the paper after the creasing plate is repositioned. Due to the restoring forces of the rubber-elastic, deformable material, the protective layer of a counter-guard plate according to the invention exhibits no such plastic deformation after the test runs.

[0009] The rubber-elastic, deformable material offers sufficiently high resistance to counterpressure, allowing precisely contoured grooves to be created in the paper using the creasing lines. At the same time, it is sufficiently flexible so that the creasing lines do not adversely compress the paper and break the paper fibers, or lead to subsequent breakage of the paper fibers when the paper is folded along the grooves. Finally, the rubber-elastic, deformable material is so non-abrasive that the punching lines penetrating this material can have a long service life.

[0010] By using the counter-guard plate according to the invention, punching plates can be used that have not only punching lines but also creasing lines, so that the material web to be punched and creasing can be both punched and creasing in a single operation. Accordingly, it is not necessary to convert an existing printing device and punch and creasing the material web in separate operations. This is economically advantageous due to the saved setup time.This is further advantageous because the creasing and punching lines are located on the same punching plate in the desired arrangement, so that firstly any adjustment times required for position correction in the otherwise necessary second work step can be completely eliminated and secondly an optimal quality of the creasing and punched paper sheets can be ensured because an undesirable offset of the punched and grilled lines in the paper sheet is excluded.

[0011] A saving in working time and an increase in the quality of work and the product quality of the finished product - namely a punched sheet of material, in particular paper - can therefore be achieved by a process in which a punching plate is produced which has not only punching lines but also creasing lines, so that it forms a combined creasing and punching plate. Furthermore, this process produces a counter-guard plate which has a flexible, tensile base plate and a protective layer made of a rubber-elastic, deformable material. The combined creasing and punching plate is then clamped into a printing device, for example, on a blanket cylinder, and the counter-guard plate is clamped onto the impression cylinder. The distance between the two cylinders depends on the material to be processed, e.g.a paper web or a paper sheet is adjusted so that the cutting lines completely penetrate the paper during operation of the device and penetrate the protective layer of the counter-guard plate. In particular, the distance between the cylinders can be adjusted so that the cutting lines also completely or at least almost completely penetrate the protective layer of the counter-guard plate, in order to ensure the desired cutting of the paper particularly safely and reliably. However, contact with the base plate of the counter-guard plate is avoided as far as possible to prevent the tip of the cutting line from being blunted or damaged by the base plate.

[0012] Because the protective layer made of rubber-elastic deformable material is arranged on a tensile-resistant base plate, the advantages of the rubber-elastic deformable material can be used without the high deformability of the material - e.g. an extensibility of several 100% - being able to impair the precision of the punching or creasing process by stretching the protective layer in the circumferential direction or in the axial direction of the impression cylinder.

[0013] In a further development, it can be provided that the protective layer is free of fibers.

[0014] The counter-guard plate can be designed so that the protective layer is free of fibers. Unlike a counter-guard plate whose protective layer contains paper fibers or fibers as reinforcement elements for other reasons, the fiber-free protective layer has a less abrasive effect on the punching lines, thus supporting the longest possible service life of the punching lines.

[0015] In a particularly preferred embodiment, it can be provided that the protective layer consists of a rubber material referred to as latex.

[0016] The counter-mudguard can be designed in such a way that the protective layer comprises a rubber material known as latex, in particular consists of such a rubber material. In the narrower sense, latex refers to the milky sap that emerges from a plant, in particular a tree, which contains rubber. Rubber can be produced from the rubber by vulcanization. In practice, however, the end products made from the rubber are often also referred to as "latex" products, e.g. latex gloves. This applies even if the rubber is not naturally obtained but synthetic. In practice, the term "latex" can therefore be used to procure the rubber-elastic, deformable material provided according to the invention, because the material is commercially available and can be ordered easily under this name.

[0017] Advantageously, the elongation at break of the intended rubber-elastic, deformable material under normal conditions can be between 400% and 900%, preferably between 500% and 850%, particularly preferably 700%. The modulus of elasticity can be, for example, between 0.1 MPa and 5 MPa, preferably between 1 MPa and 4 MPa, particularly preferably 3 MPa (in particular at an elongation of 500%). An advantageous tensile strength (crescent) can be between 50 N / mm and 80 N / mm, preferably 70 N / mm, and / or the Shore hardness can be between 30 and 40, preferably 35. Furthermore, it can be provided that the rubber-elastic, deformable material is food-safe, for example, to enable the punching of food packaging or the like without additional protective measures.

[0018] Furthermore, it can be provided that the protective layer has a thickness of 0.4 mm to 1 mm, preferably 0.7 mm.

[0019] The counter-shield can be designed such that the protective layer, in particular the aforementioned latex-coated protective layer, has a thickness of 0.2 mm to 1 mm, preferably 0.4 to 0.8 mm, and particularly preferably 0.7 mm. Due to the rubber-elastic deformability, an excessively thick protective layer can impair the precision of the desired lines in the paper. In initial, non-public tests, a protective layer 0.7 mm thick produced excellent results in terms of precisely designed and easily foldable grooves, as well as reliable cutting of the paper along the punching lines.

[0020] For further development, it may be provided that the protective layer is designed as a material cut from a web.

[0021] The counter-guard plate can be designed in such a way that the protective layer is formed as a material cut from a web. In contrast to, for example, initially applying a liquid material to the base plate and then curing, solidifying, polymerizing, and / or setting this liquid material to create the protective layer, the use of a prefabricated semi-finished product in the form of a web can ensure that a specific thickness of the protective layer is maintained with high precision across the entire surface of the protective layer. In practice, terms such as rubber blanket, rubber film, latex cloth, latex fabric, latex film, latex web, or similar are used, under which rubber-elastic, deformable material is commercially and economically available as web material in various thicknesses.

[0022] Preferably, the protective layer may be made of a non-foamed material.

[0023] The counter-guard plate can be designed such that the protective layer comprises a non-foamed material, in particular consisting of a non-foamed material. Given the thinness of the protective layer, a non-foamed material is more stable and thus easier to process during production of the counter-guard plate than a foamed material such as latex foam. Furthermore, the non-foamed material ensures the desired counter-pressure that the counter-guard plate is intended to exert on the paper, allowing the creasing or punching lines to act on the paper in the desired manner.

[0024] Furthermore, it can be provided that the base plate has a thickness of 0.1 mm to 0.3 mm, preferably 0.15 mm.

[0025] The counter-guard plate can be designed such that the base plate has a thickness of 0.1 mm to 0.3 mm, preferably 0.15 mm. The low thickness of the base plate eliminates undesirable influences from the tensile material when it is applied to the impression cylinder and is thus compressed on its underside or radially inner side and stretched on its top side or radially outer side. Furthermore, the low thickness of the base plate supports a secure hold of the counter-guard plate on the impression cylinder by keeping restoring forces as low as possible, which counteract the curvature of the counter-guard plate and tend to lift the counter-guard plate from the impression cylinder.

[0026] In one embodiment, it may further be provided that the base plate is made of steel.

[0027] The counter-guard plate can be designed in such a way that the base plate is made of steel. This material has proven itself in practice: the counter-guard plate with a thin steel base plate not only has the desired tensile strength, but also the desired flexibility to allow it to be easily bent and applied to the impression cylinder. Furthermore, depending on the design of the steel material, a magnetic attachment or a material-to-material, particularly adhesive, attachment to the impression cylinder can be made possible. Alternatively, initial, non-public tests have shown that a base plate can be made of a plastic material, in particular made of a plastic material, without compromising the previously described required properties.Likewise, material combinations or alternative materials that are similarly hard can be the subject of further design.

[0028] A second aspect of the invention relates to the use of a rubber-elastic deformable material as a protective layer on a counter-guard plate of a punching device.

[0029] Rubber-elastic materials are used in practice for reasons of electrical insulation, slip resistance, or due to their damping properties. The use of a rubber-elastic material as a protective layer on a counter-guard plate of a punching device therefore also represents an aspect of the present invention. In this application, the counter-guard plate can be particularly advantageously designed as explained above with reference to the various design options described.

[0030] Further features, details, and advantages of the invention emerge from the wording of the claims. The invention is not limited to one of the above-described embodiments, but can be modified in a variety of ways. All features and advantages emerging from the claims, the description, and the drawings, including structural details, spatial arrangements, and method steps, can be essential to the invention both individually and in a wide variety of combinations.

Claims

[1] Counter mudguard, with holding means designed to hold the counter-guard plate on a counter-pressure cylinder of a punching device during use, wherein the counter-guard has a flexible, tensile base plate made of a first material, and a protective layer which, in use, forms the radially outer surface of the counter-mudguard and consists of a second material which is softer than the first material, characterized by , that the protective layer consists of a rubber-elastic deformable material. [2] Counter-mudguard according to claim 1, characterized by that the protective layer is free of fibers. [3] Counter-mudguard according to claim 1 or 2, characterized by that the protective layer is made of a rubber material called latex. [4] Counter-mudguard according to one of the preceding claims, characterized bythat the protective layer has a thickness of 0.4 mm to 1 mm, preferably 0.7 mm. [5] Counter-mudguard according to one of the preceding claims, characterized by that the protective layer is designed as a material cut from a web. [6] Counter-mudguard according to one of the preceding claims, characterized by that the protective layer is made of a non-foamed material. [7] Counter-mudguard according to one of the preceding claims, characterized by that the base plate has a thickness of 0.1 mm to 0.3 mm, preferably 0.15 mm. [8] Counter-mudguard according to one of the preceding claims, characterized by that the base plate is made of steel. [9] Use of a rubber-elastic deformable material as a protective layer on a counter-guard plate of a punching device. [10] Use according to claim 9, characterized bythat the counter-mudguard is designed according to one of claims 1 to 8.