Crimping and coining device for processing a steel panel

Abstract

A device (1) for crimping and coining a metal product comprises a mold formed by an upper part (2) and a lower part (3), each of which carries a rotating roller (4) on which a first tool (5) is mounted, which provides raised elements (6) on one of said tools (5) and corresponding recessed elements (7) on the other tool (5) so as to form a punch / die system suitable for performing a coining operation, and each roller (4) also carries at least one other similar tool (S') parallel to it and angularly spaced, which differs from it in terms of the coining elements (6', 7'), means (8, 9) also being provided for the synchronized rotation of the rollers (4), configured to place the pair of tools (5, S') selected for the work in progress at an opposite working position.

Description

[0001] CRIMPING AND COINING DEVICE FOR PROCESSING A STEEL PANEL

[0002] The present invention relates to a crimping and coining device for processing a steel panel, typically used to produce the cylindrical shell of a washing machine or dryer drum, and a related station comprising said device in which other processing steps are also performed (e.g., calendering, preparation of crimping flaps). In the following, specific reference will be made to the production of a washing machine drum, but it is clear that the device described here and the station comprising it can be applied to the production of other products that use a metal strip as the starting material and require the same processing steps, such as air conditioning or ventilation ducts (HVAC sector) and containers (e.g., cans, bins) for packaging food and non-food products.

[0003] As is well known, a washing machine includes a drum into which the items to be washed are loaded, this drum having a cylindrical shape with perforated walls to allow the washing liquid to enter and exit. To create this cylindrical shape, a stainless steel strip wound in a coil is unwound by a unwinding reel, which feeds the strip to a bench on which various tools and devices are placed to hold the strip, cut a rectangular panel from it, and form the aesthetic geometry and deep-drawn holes for water drainage on said panel. The panel thus processed is then joined with one short side folded over the other to form a cylindrical shell which, thanks to subsequent processing, will become the drum of a domestic washing machine / dryer. This joining of the two short sides of the rectangular panel can be either mechanical (crimping) or by fusion of the overlapping joint by resistance welding, or of the butt joint by laser or plasma welding.

[0004] In the case of mechanical joining by crimping, which is done by overlapping the end flaps of the panel and folding them twice over themselves using a mold, the tensile strength of the joint is increased by performing the crimping operation together with the coining operation. For this purpose, the crimping die, which consists of an upper part and a lower part, has raised elements on one part and corresponding recessed elements on the other part, thus forming a punch / die system that causes localized deformation of the joint. This deformation reinforces the joint, making it more difficult for the two crimped flaps, which are no longer flat, to slide relative to each other, thus increasing the tensile and peel strength of the joint in pull -off tests, so that the drum structure is more robust both for its end use and in the processing stages following crimping. KR 2011 / 0067640A describes a device of this type according to the preamble of claim 1.

[0005] A characteristic aspect of the production of any type of crimped product (drums, pipes, containers) is that the coining must only extend partially along the joint, as the end portions of the joint are usually subject to subsequent processing. For example, in the case of a drum, at the ends of the cylindrical shell thus formed it is necessary to create flanges with or without circumferential grooves for the assembly of the pieces that form the mouth of the drum at one end and the bottom of the drum at the other end.

[0006] The crimping and coining die must therefore be specific for each depth size of the product to be manufactured, since as the length of the joint varies, so must the extension of the punches and dies that constitute the coining elements. Consequently, since a processing station comprising the crimping and coining device is typically capable of manufacturing products in a wide range of sizes, there is the problem of replacing the mold (or parts of it) each time the size of the product being processed changes.

[0007] This clearly involves the inconvenience of stopping production and entering the operating area of the line containing the station in question to change the mold. Usually, the line is protected by nets equipped with electro-controlled doors that, when opened, activate the switch on the electrical panel and cause the station devices to move to a safe position, which then requires time to reset after the mold has been replaced.

[0008] The purpose of the present invention is therefore to provide a crimping and coining device that overcomes the above-mentioned drawbacks. This purpose is achieved by means of a device in which the mold comprises a pair of rollers, each of which carries a plurality of tools for crimping and coining products of different sizes, said device also comprising actuators for rotating said rollers in order to select the appropriate pair of tools for the product being processed.

[0009] The main advantage of the device in question is therefore that it allows the size of the product being processed to be varied without having to manually replace the mold, as is the case in prior art stations. This translates into lower costs and higher productivity, thanks to the elimination of the labor and machine downtime required for traditional mold replacement.

[0010] Another important advantage of the aforementioned device, in its preferred form, is that it allows automatic selection of the pair of tools according to the size of the product detected by appropriate sensors, thus eliminating potential selection errors by the operator.

[0011] Yet another advantage of this device lies in the fact that it is made with components of limited cost and size, so that a station incorporating it costs only slightly more than a traditional station, since all the other components of the station remain unchanged, as does the production process.

[0012] Further advantages and features of the device according to the present invention will be apparent to those skilled in the art from the following detailed description of one embodiment thereof with reference to the accompanying drawings, in which:

[0013] Fig.1 is a partial perspective view from above of a processing station comprising a device according to the present invention;

[0014] Fig. 2 is a perspective view from below of the upper part of the aforementioned device;

[0015] Fig. 3 is a perspective view from above of the lower part of the aforementioned device; and

[0016] Fig. 4 is a perspective view from above of the aforementioned device with the mold closed in the final operating position with a first pair of selected tools, but without the jointed panel, which has been omitted for clarity.

[0017] Referring to Fig.1, it can be seen that a processing station traditionally comprises a frame structure carrying a plurality of tools and devices, including a pair of molds S1, S2 for folding the short sides of a rectangular panel previously cut from a stainless steel strip and subjected in sequence to the forming, deep drawing and blanking stages in one or more previous stations of the line. After the short sides have been prepared for crimping, a pair of picking and rotating arms B1, B2 convert the panel from a flat structure to a cylindrical structure, bringing the short sides into overlap at the crimping and coining device 1.

[0018] Once these operations have been completed, the joined panel is sent to the subsequent stages of transformation into a finished washing machine drum. The molds S1, S2, and arms B1, B2 are not described in detail since their structure and operation are known to a person skilled in the art as they are prior art devices. With reference to Figures 2-4, the innovative device 1 according to the invention is now illustrated, comprising a mold formed by a movable upper part 2 and a fixed lower part 3. Each part comprises a roller 4 carrying a plurality of tools 5, 5' (two in the example shown) arranged longitudinally and angularly spaced so as to extend along the folded sides to be crimped in correspondence with the corresponding opposing tools on the other part of the mold.

[0019] The tools 5, 5' mounted on one of rollers 4, for example that of the upper part 2, have a series of punches 6, 6' that extend along a coining zone and cooperate with corresponding dies 7, 7' formed on the tools 5, 5' of the other roller 4, i.e. that of the lower part 3 in the example illustrated. In this example, the coining area of the first tool 5 is larger than that of the second tool 5', as better illustrated in Fig.3, so that the operator can select the pair of tools 5 or 5' depending on the height of the panel being processed.

[0020] This selection is made by rotating the two rollers 4 in a synchronized manner so that the required pair of tools is positioned opposite each other to act on the panel when the mold is closed, for example, the first pair of tools 5 as shown in Fig.4, while the other pair 5' is rotated to a non-operating position. The selection can be made manually by the operator via a specific interface, or the device can also include a control unit (not shown) that detects the dimensions of the product being processed using specific sensors and automatically selects the correct pair of tools.

[0021] The rotation of rollers 4 is performed using known rotation means, for example with a rack and pinion mechanism. More specifically, as shown in Figures 2 and 4, in which the proximal support of rollers 4 has been removed for clarity, each roller 4 has a pinion 8 at one end, which is integral with it and coaxial with its axis of rotation, which is engaged by a rack 9, preferably controlled by a pneumatic or electric actuator. The movement of rack 9 causes roller 4 to rotate to the angular position corresponding to the selected pair of tools.

[0022] It is clear that the embodiment of the device according to the invention described and illustrated above is only one example that is subject to numerous variations. In particular, the number and spacing of the tools on rollers 4 can vary freely depending on construction requirements, as can the means of rotation of rollers 4 (e.g., gears driven by an electric motor or a ratchet mechanism). Furthermore, the arrangement of the coining elements may vary as long as their relative positioning is maintained, so that the location of the punches and dies may be reversed (punches on part 2 and dies on part 3), as may the movement of the two parts 2 and 3 of the mold, which may also both be movable.

[0023] Finally, rollers 4 may have any cross-sectional shape (circular, polygonal, irregular), and the dimensions and / or shape of the pairs of punch / die elements on the tools and their longitudinal spacing may also vary.

Claims

CLAIMS1. A device (1) for crimping and coining a metal product comprising a mold formed by an upper part (2) and a lower part (3), each of which carries a tool (5) which provides raised elements (6) on one of said tools (5) and corresponding recessed elements (7) on the other tool (5) so as to form a punch / die system suitable for obtaining a coining, as well as actuation means for closing said mold on a metal product being processed by means of mutual approach of said parts (2, 3) of the mold, said device (1) being characterized in that each part (2, 3) of the mold further comprises a rotatable roller (4) carrying said tool (5) and also carrying at least one other similar tool (5') parallel thereto and angularly spaced which differs from it in coining elements (6‘, 7'), and in that it further comprises means for the synchronized rotation of said rollers (4) configured to arrange in opposing working position the pair of tools (5, 5') selected for the current processing.

2. A device (1) according to claim 1, characterized in that it comprises a control unit configured to detect the dimensions of the product being processed by means of appropriate sensors and automatically select the correct pair of tools (5, 5').

3. A device (1) according to claim 1 or 2, characterized in that the means for the synchronized rotation of the rollers (4) comprise a pinion (8), integral with the roller (4) and coaxial to its axis of rotation, and a rack (9) engaging said pinion (8).

4. A device (1) according to claim 3, characterized in that, the rack (9) is driven by a pneumatic or electric actuator.

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