EP3309096B1

EP3309096B1 - Device for removing a metal strap from a sheet coil

Info

Publication number: EP3309096B1
Application number: EP17195723.6A
Authority: EP
Inventors: Gian Mario FOPPA VINCENZINI
Original assignee: Asservimentipresse Srl
Current assignee: Asservimentipresse Srl
Priority date: 2016-10-13
Filing date: 2017-10-10
Publication date: 2019-05-22
Anticipated expiration: 2037-10-10
Also published as: EP3309096A1; PL3309096T3; IT201600102867A1; TR201909679T4; ES2742882T3

Description

The present invention relates to a device for removing a metal strap from a sheet coil.
As is known, a sheet coil is obtained by winding a sheet in the form of a strip around itself. As the sheet stores elastic energy during the winding step the coil tends to open. In order to prevent this, a plurality of straps (bands of metal material of different thickness and length) are wrapped around the coil. In particular, each strap is positioned circumferentially around an outer surface of the sheet, and transversely on the end faces of the coil. These transverse straps are also positioned longitudinally inside a central hole of the same coil and on the outer surface of the coil orthogonally to the circumferential straps. The straps thus surround the coil internally and externally and hold it closed upon itself.
When the sheet is to be used, it is necessary to cut each metal strap to release the same sheet. This cut is carried out in different ways. For example, the cut can be carried out manually using special scissors or similar tools and or even a hammer and chisel. However, this process is very dangerous for the operator as the head of the coil, i.e. the start of the strip wound around itself (in a spiral) tends to spring towards the outside of the coil as soon as the strap is cut. This occurs due to the elasticity of the sheet, i.e. the elastic energy stored during the winding step. This outward movement of the head of the coil can be dangerous for the operator carrying out cutting of the straps.
These problems occur even if the coil is mounted, to carry out cutting of the straps, on a decoiler and is retained by one or more pressure arms, which manage only to reduce the spring of the head of the coil, but not to eliminate it completely.
There is also known a process for removing a strap from sheet coils that tends to overcome the problems of the manual process described above. This solution is the subject matter of a previous patent IT 1366420 by the same Applicant and provides for the use of two electrodes that are brought into contact with the metal strap. By sending a low voltage and high intensity current to the two electrodes, this current passes inside a short section of the strap, heating it and melting it. The intrinsic tension of the coil, which tends in any case to unwind, causes breakage of the strap in the portion between the two electrodes. Advantageously, air must be provided between the strap and the coil, air that preferably is only present where the head of the coil starts.
Document GB 2242417 A discloses a device for removing a thermoplastic adhesive tape from a coil of sheet material. The device is provided with a heating element capable of causing breakage of the adhesive tape. However, the heating element is fixed relative to the adhesive tape and, consequently, relative to the coil of sheet material.
Document WO 85/01532 A1 discloses a method and a device for the magnetic heating of a coil of sheet material. The device is hinged on a support element to move away from or towards the coil, so that it can carry out a movement only in one direction relative to this coil.
Finally, document EP 0438130 A2 discloses a device for electromagnetic induction heating for straightening sheet material. However, this device is not provided with specific means for movement of the frames that form the heating elements.
All these technical solutions, although optimal, are improved according to the present invention, as it is necessary for the removing device to be positioned easily and precisely on the side of the sheet coil.
In fact, the object of the present invention is to provide a device for removing a metal strap from a sheet coil that is improved over prior art solutions.
In particular, an object of the present invention is to provide a device of the aforesaid type that can be used by an operator who remains at a distance from the sheet coil, that allows breakage of each strap closing this coil and that is in any case extremely safe for the operator carrying out the cutting operation of each strap.
Another object is to provide a device of the aforesaid type that does not require the introduction of electricity in the strap (and consequently in the sheet coil).
A further object is to provide a device of the aforesaid type that is compact and easy to position on the side of a sheet coil.
These and other objects, which will be apparent to a person skilled in the art, are achieved by a device according to the content of the appended claims.
For a better understanding of the present invention there are attached, purely by way of non-limiting example, the following drawings, wherein:

figure 1 shows a front view of a sheet coil provided with straps that hold it closed;
figure 2 shows, enlarged, the detail indicated with the letter A in figure 1, and schematically a part of the device according to the present invention;
figure 3 shows a view analogous to figure 2 but during a phase of cutting of the strap;
figure 4 shows a view analogous to figure 2 but in an advanced phase of the strap cutting process;
figure 5 shows a block diagram of the device according to the present invention;
figure 6 shows a rear view of a first embodiment of the device according to the present invention;
figure 7 shows a side view of the part of the device of figure 6;
figure 8 shows an exploded view of the part of the device according to the invention shown in figures 6 and 7;
figure 9 shows a side view of a second embodiment of the device according to the present invention;
figure 10 shows a top view of the device of figure 9; and
figure 11 shows an embodiment of the movement and adjustment means associable with the device according to the present invention.

With reference to figure 1, a sheet coil is generally indicated with reference number 1. As shown, the coil 1 is provided with a plurality of layers of one-piece metal sheet superimposed in the form of a spiral and held closed by means of a plurality of metal straps 3 and 4. In particular, each strap 3 is a transverse strap that surrounds the end parts of the coil 1 and is arranged on the outer surface 5 of this coil 1, parallel to the longitudinal axis of the same coil 1 and inside a hole 6 of this coil 1. The strap 4, or circumferential strap, is instead arranged on the surface 5 of the coil 1, around it.
Preferably, a plurality of straps 4 is arranged on the surface 5 of the coil 1.
The sheet coil 1 is provided with a head 6 and, in proximity of this head 6, a space 7 is provided between the coil 1 and each strap 4 arranged circumferentially on the surface 5 of this coil 1.
According to the present invention, a removing device 10 is designed to operate in the space 7, said removing device 10 being configured to carry out the separation of the strap 4 into two parts.
Generally, the removing device 10 comprises a melting heating element 11 that is defined by an electric resistor (acting as inductor) in which the electric current is made to pass. The melting heating element or inductor 11, when passed through by the electric current, generates an oscillating magnetic field. When the inductor 11 is taken in proximity of the strap 4, the current that passes through the inductor 11 causes or induces a current in the strap 4 through the Joule effect. This causes heating of the strap 4 and therefore its localized melting, i.e. melting thereof in a portion 13 positioned in front of the melting heating element or inductor 11. At this point, the intrinsic tension of the wound coil 1, tension that tends to cause the head 6 of the coil 1 to open, generates a force F (see figure 4) acting on the same head 6 of the coil 1 that tends to press on the strap 4 from the inside of the same strap 4. This force F causes breakage of the heated portion 13 of the strap 4 and consequently cutting of the strap 4.
The melting element or inductor 11 is taken to a distance comprised between 0.5 and 3 mm to be effective in the action on the strap 4. Moreover, in order to obtain correct heating and, consequently, breakage of the strap 4, the heating induced on the strap 4 is carried out on a portion 13 having a length ranging between 8 mm and 12 mm.
Naturally, the melting element or inductor 11 can also be taken in proximity of portions of the straps 4 that are not positioned at the head 6 of the sheet coil 1, i.e., that are not positioned at the aforesaid space 7.
More in particular, the removing device 10 according to the present invention will now be described with reference to possible embodiments thereof, given purely by way of non-limiting example, shown in figures 5 to 10.
The removing device 10 according to the present invention comprises, in general terms, a current generator 20, for example solid-state, of compact size and supplied via normal connection to the electricity network 21 or via a battery. Operation of the current generator 20 is controlled via a microprocessor control unit 23.
The current generator 20 is connected to at least one heating or melting element 11. Figure 5 shows two melting elements 11 arranged on both sides of the current generator 20 and designed to operate both on the left side and on the right side of this current generator 20. The current generator 20 contained in a power unit 24, known per se, is connected to a heating member 25 of the melting element 11 and is activated by a drive member 26, which can be a pedal drive. Naturally, other types of drives of the current generator 20 are possible for the person skilled in the art.
The removing device 10 comprises a heating head 30 of the melting element or inductor 11. The heating head 30 comprises a body 30A supported by a support apparatus 31. Between the heating head 30 and the support apparatus 31 there is interposed a connection element 32. According to the embodiment of figures 6 to 8, the connection element 32 consists of a flat structure sliding on a base 33. According to the embodiment of figures 9 and 10, at least one actuator cylinder 34, which can be of hydraulic, pneumatic or electrical type, is operatively associated with the connection element 32.
The heating head 30 is movable and tiltable relative to the support apparatus 31 and, consequently, relative to each strap 3 or 4. The removing device 10 is in fact provided with manual movement and adjustment means, which comprise, for example, micrometer screws 36, or motorized movement and adjustment means, which comprise the aforesaid actuator cylinders 34 with respective stepper motors (not shown), interposed between the heating head 30 and the support apparatus 31 to carry out movement of this heating head 30 relative to this support apparatus 31. Preferably, according to the embodiment of figures 6 to 8, there are provided one or more micrometer screws 36 interposed between the body 30A of the heating head 30 and the flat structure 32 of the support apparatus 31.
Movement of the heating head 30, adjusted in a precise manner, allows optimal positioning of the heating or melting element 11 in the operating area on the strap 3 or 4. Movement of the heating head 30 is therefore adjustable along horizontal axes orthogonal to one another, and can be carried out by means of a tilting of the heating head 30 in a vertical direction. It is also possible to rotate the heating head 30 by a predefined angle, preferably equal to 360°.
The heating head 30 comprises a metal connector or lead 37 to the end of which there is welded the inductor 11 generating the electromagnetic field. Above the connector 37 there is preferably a pilot light provided that indicates operation of the heating head 30. On the back of the aforesaid heating head 30 there is provided the output of a power supply cable 40 connected to the current generator 20. The lead 37 can have a variable length and comprise pipes 38a, 38b arranged parallel to each other containing resistive metal wires designed to define the inductor 11 projecting from the lead 37.
Figure 11 shows, by way of non-limiting example, some components of the movement and adjustment means associable with the heating head 30, with the support apparatus 31 and with the respective connection element 32. As shown in figure 11, the heating head 30, the support apparatus 31 and/or the respective connection element 32 are arranged to carry out a plurality of distinct and independent movements relative to the coil 1 on which the straps 3 and 4 are positioned. For example, the heating head 30 can carry out a rotation movement about a first vertical axis A passing through said heating head 30. The connection element 32 can carry out a rotation movement about a second horizontal axis B passing through this connection element 32. The assembly formed by the heating head 30 and by the connection element 32 can carry out a translation movement relative to the support apparatus 31 along a third horizontal axis C passing through this support apparatus 31. The assembly formed by the heating head 30 and by the connection element 32 can also carry out a rotation movement relative to the support apparatus 31 about a fourth vertical axis D passing through this support apparatus 31. Finally, the assembly formed by the heating head 30 and by the connection element 32 can carry out a translation movement relative to the support apparatus 31 along a fifth horizontal axis E passing through this support apparatus 31 and perpendicular to the third horizontal axis C.
The combination of the aforesaid movements, and the operation of the heating head 30, can be carried out manually, using the related selectors and push buttons positioned on a control panel 35 of the removing device 10, or by means of a semi-automatic or automatic cycle.
The heating head 30 is cooled, by means of a fluid coolant, by a cooling device 22. The cooling is also provided for the lead 38. The lead 38 is preferably welded to the body 30A of the heating head 30.
The inductor 11 used for the heating head 30 can have powers ranging between 2 kW and 4.5 kW. The specific current intensities can be calculated as a function of the section of the strap to be cut. By means of a current intensity of the order of 13A/16A it is possible to melt a normal strap 3 or 4 used to hold a closed sheet coil.
The heating head 30 is subject to motor means (hydraulic or pneumatic, not shown) or is movable manually in order to be moved towards the strap 3 or 4 when this requires to be cut.
In this regard, when the heating head 30 is moved towards the strap, the current that passes through the resistor acting as inductor 11 generates an oscillating magnetic field that causes an induced current in the strap, overheating and therefore melting it. The intrinsic tension of the sheet coil (which tends to unwind) favours complete breakage of the strap, i.e., its separation into two parts.
The device 10 can be used in any position of any strap, although it is preferable to use it in the space 7 between the strap 4 and the sheet coil. This facilitates the opening of the strap in a position in which this strap is not in contact with the sheet and is particularly subject to the force F of the strip that tends to unwind.
There have been described some particular embodiments of the present invention. However, a person skilled in the art may provide other possible embodiments in the light of the preceding description, solutions that must be considered as falling within the scope of the claims below.

Claims

A device for removing a metal strap (3, 4) from a sheet coil (1) comprising breaking means (11) of the strap (3, 4), designed to allow said strap (3, 4) to be removed from the sheet (1), wherein the breaking means are a heating element (11) designed to be positioned at, but at a distance from, a part (13) of the strap (3, 4) to heat it so as to allow breakage of the strap (3, 4) and removal from the sheet coil (1), the device being characterized in that said heating element (11) is movable relative to the strap (3, 4) and is carried by a heating head (30) that is associated with a support apparatus (31), wherein the removing device (10) is provided with movement and adjustment means (34, 36) interposed between the heating head (30) and the support apparatus (31) to carry out the movement of said heating head (30) relative to said support apparatus (31) along at least two spatial axes orthogonal to one another, said movement and adjustment means (34, 36) being designed to allow tilting in vertical direction and rotation by a predefined angle of said heating head (30).
The device according to claim 1, characterized in that said heating element (11) consists of an electric resistor in which current circulates when taken in proximity of the part (13) of the strap (3, 4) to be heated, heating of said part (13) taking place through magnetic induction.
The device according to claim 2, characterized in that said electric resistor (11) is carried in a cantilevered fashion from said heating head (30) and is associated with leads (38) projecting from said heating head (30), the heating head (30) being cooled by means of a coolant fluid.
The device according to any one of claims 1 to 3, characterized in that between said heating head (30) and said support apparatus (31) a connection element (32) is interposed, wherein said heating head (30), said support apparatus (31) and/or the respective connection element (32) are arranged to carry out a plurality of distinct and independent movements relative to the sheet coil (1) on which the straps (3, 4) are positioned, and wherein said movements are selected in the group consisting of:
- a rotation movement of said heating head (30) about a first vertical axis (A) passing through said heating head (30);

- a rotation movement of said connection element (32) about a second horizontal axis (B) passing through said connection element (32);

- a translation movement of the assembly formed by said heating head (30) and by said connection element (32) relative to said support apparatus (31) along a third horizontal axis (C) passing through said support apparatus (31);

- a rotation movement of the assembly formed by said heating head (30) and by said connection element (32) relative to said support apparatus (31) about a fourth vertical axis (D) passing through said support apparatus (31); and

- a translation movement of the assembly formed by said heating head (30) and by said connection element (32) relative to said support apparatus (31) along a fifth horizontal axis (E) passing through said support apparatus (31) and perpendicular to said third horizontal axis (C).
The device according to claim 4, characterized in that said movement and adjustment means (34, 36) comprise at least one actuator cylinder (34) associated with said connection element (32), said actuator cylinder (34) being alternatively hydraulically, pneumatically or electrically driven.
The device according to claim 4, characterized in that said connection element (32) is formed by a flat structure sliding on a base (33), wherein the movement and adjustment means (36) comprise one or more micrometer screws (36) interposed between the body (30A) of the heating head (30) and the flat structure (32) of the support apparatus (31).
The device according to any one of the preceding claims, characterized in that the part (13) of the strap subjected to heating is positioned at a head (6) of the sheet coil (1) and in particular at a space (7) between the sheet and the strap.