Induction sealing system

Abstract

The present disclosure relates to an induction sealing system for heat sealing packaging material for producing sealed packages of pourable food products, said sealing system may include a sealing jaw and a counter-jaw. In some embodiments, the sealing jaw may include at least one inductor device having at least one active surface configured to contact said packaging material; at least one flux-concentrating insert; a supporting body including heat-conducting material, said supporting body housing, said at least one inductor device and said flux-concentrating insert; and an interactive surface configured to press against said packaging material. In some embodiments, the counter-jaw may include at least one pressure pad made of elastomeric material, said at least one pressure pad configured to provide a counter pressure to the sealing jaw, wherein said at least one pressure pad has an arched convex contact area with height in the direction towards the sealing jaw.

Claims

1. An induction sealing system for heat sealing packaging material for producing sealed packages of pourable food products, said sealing system comprising: a sealing jaw consisting of: at least one inductor device having at least one active surface facing said packaging material when in use; an insert comprising magnetic flux-concentrating material; a supporting body comprising heat-conducting material, wherein said at least one inductor device and said insert are housed within said supporting body; and a plastic member securing the insert and the at least one inductor device to the supporting body, the plastic member comprising an interactive surface configured to press against said packaging material when in use and a ridge protruding outward from the interactive surface of the plastic member and extending along a length of the sealing jaw; and a counter-jaw comprising at least one pressure pad made of elastomeric material, said at least one pressure pad configured to provide a counter pressure to the sealing jaw, wherein said at least one pressure pad has an arched convex contact area, wherein the arched convex contact area comprises ends and a middle portion between the ends, the middle portion closer to the sealing jaw than to the ends, wherein an apex of the arched convex contact area is aligned with the ridge of the plastic member of the sealing jaw; wherein said at least one inductor device comprises a first inductor device having a first active surface and a second inductor device having a second active surface; and wherein said ridge of said plastic member is positioned between and is spaced from the first and second active surfaces.

2. The induction sealing system according to claim 1, wherein said ridge is aligned with a center of a width of the at least one pressure pad.

3. The induction sealing system according to claim 1, wherein said apex of the arched convex contact area is aligned with a center of a width of the at least one pressure pad.

4. The induction sealing system according to claim 1, wherein a width of said at least one pressure pad is equal to or larger than a combined width of said at least one active surface and said interactive surface when the at least one pressure pad is compressed during use.

5. The induction sealing system according to claim 1, wherein said at least one inductor device is made of copper.

6. The induction sealing system according to claim 1, wherein said plastic member comprises a width that is orthogonal to the length of the sealing jaw, and wherein said ridge is aligned with a middle of the width of the plastic member.

7. The induction sealing system according to claim 1, wherein: said supporting body comprises a cutting groove, said cutting groove at least partially separating: the supporting body into a first portion and a second portion; the plastic member into a first portion and a second portion; and the insert into a first portion and second portion; said first portion of the plastic member secures the first portion of the insert to the first portion of the supporting body; and said second portion of the plastic member secures the second portion of the insert to the second portion of the supporting body.

Description

DESCRIPTION OF THE DRAWINGS

(1) In the following the present invention will be described in greater detail together with the accompanying drawings, in which

(2) FIG. 1 is cross sectional view of a package unit comprising two induction sealing systems according to the prior art.

(3) FIG. 2 is cross sectional view of the induction sealing system according to the present invention having a sealing jaw and a counter-jaw.

DETAILED DESCRIPTION

(4) Number 1 in FIG. 1 indicates as a whole a packaging unit for producing aseptic sealed packages 2 of a pourable food product, such as pasteurized or UHT milk, fruit juice, wine, etc., from a tube 3 of packaging material.

(5) The packaging material has a multilayer structure (not shown), and comprises a layer of fibrous material, normally paper, covered on both sides with respective layers of heat-seal plastic material, e.g. polyethylene; and the side of the packaging material eventually contacting the food product in package 2 also has a layer of electrically conductive barrier material, e.g. aluminium, in turn covered with one or more layers of heat-seal plastic material.

(6) Tube 3 is formed in known manner upstream from unit 1 by longitudinally folding and sealing a web of heat-seal sheet material, is filled with the sterilized or sterile-processed food product, and is fed by known devices (not shown) along a vertical path in a direction A.

(7) Unit 1 comprises two forming assemblies 4, which move vertically along respective rails (not shown) and interact cyclically and successively with tube 3 to grip it at equally spaced cross sections and perform induction heat-seal and cutting operations on tube 3.

(8) Each forming assembly 4 substantially comprises a slide (not shown) which runs along the respective rail; and two jaws 5, 6 (only shown as necessary for a clear understanding of the present invention) hinged to the slide about respective horizontal axes, and movable between a closed position and a fully-open position.

(9) In the example shown, jaws 5, 6 of each forming assembly 4 have respective arms 7, 8, which interact with tube 3, extend parallel to a direction B perpendicular to direction A, and are located on opposite sides of tube 3.

(10) Each forming assembly 4 also comprises two facing forming shells 9, 10 hinged to respective jaws 5, 6 and movable between an open position, into which they are pushed by elastic means (not shown), and a closed position, in which they mate to form a space defining the shape and volume of package 2 to be formed in between.

(11) Each forming assembly 4 also comprises an induction sealing jaw 15 and a counter-jaw 16 comprising a cutting knife 32 for respectively performing, on each cross section of tube 3 of packaging material gripped between relative jaws 5, 6, an induction heat-seal operation and a cutting operation along the centre line of the cross section.

(12) The induction sealing system has two sets of jaw-pairs 5, 6 according to the prior art for sealing the tube to make separate pillows intended to become separate packages when cut from each other and folded properly. The induction sealing system has a transversal induction sealing jaw 15 having a supporting body 24 housing a flux-concentrating insert 30 which flux-concentrating insert 30 houses inductor device 20, 21. The inductor device have active surfaces adapted to be pressed against a packing material surface (not shown) to induce current and thereby heat in a metal layer of the packing material during a sealing process. The inductor device 20, 21 and the flux-concentrating insert 30 are locked to the supporting body by a moulded plastic member. The plastic member will also have an outer surface that will be pressed against the packing material during a sealing operation.

(13) The induction sealing system of the prior art also comprises a counter-jaw 15 comprising two pressure pads 31 made of heat-resistant elastomeric material, preferably nitrile rubber, and housed in respective front cavities of the same shape formed in jaw 5 of relative forming assembly 4 and located symmetrically on opposite sides of the centre line A. Pressure pads 31 of each jaw 5 cooperate with active surfaces 25, 26 of inductors 20, 21 of relative jaw 6 to grip and heat seal tube 3 on opposite sides of the centre line A.

(14) With reference to FIG. 1, counter-jaw 16 comprises a substantially flat cutting member 32, which is housed in sliding manner inside a front seat on jaw 5 of relative forming assembly 4, is movable towards the centre line A, and is activated in known manner, not shown, by a hydraulic cylinder built into jaw 5.

(15) Cutting member 32 is normally maintained in a withdrawn rest position, housed completely inside jaw 5, by known elastic means (not shown), and is moved by the relative hydraulic cylinder into a forward cutting position, in which it projects frontwards from jaw 5, engages recess 33 in sealing jaw 15 of relative jaw 6, and cuts along the centre line of the relative cross section of tube 3.

(16) FIG. 2 is cross sectional view of the induction sealing system according to the present invention having a sealing jaw 15 and a counter-jaw 16. The sealing jaw 15 has a supporting body 24 housing a flux-concentrating insert 30, two inductor devices 20, 21 on each side of the cutting groove 33. The parts are fastened by the plastic member 19 comprising the interactive surface 55 surrounding the active surfaces 25, 26 of the inductor devices 20, 21. A ridge 51 is present protruding from the plastic member 19 on each side of the cutting groove along the centre line C of each side of the sealing jaw 15.

(17) The counter jaw 16 comprises a supporting body 56 housing two pressure pads 52. The pressure pads have arced convex contact surfaces 53 where the greatest height of the convex shape, in the direction towards the sealing jaw, of each of the pressure pads, is aligned with the centre line C. The pressure pads 52 are thus to arranged to meet the ridges 51 on opposite sides of the package material (not shown in FIG. 2). The arced convex contact surfaces 53 will be compressed the jaws 15, 16 are pressed together. The shape of the pressure pads 52 are made so that the pressure pads 52 will present a uniform pressure to the sealing jaw 15 when the jaws 15, 16 are completely pressed together and the pressure pads 52 are compressed. When compressed, the width (perpendicular to the centre line C) of the pressure pads 52 will increase so that the entire contact area, 55, 25, 51, 26 of the sealing jaw 15 is exposed to the uniform pressure by the counter-jaw 16. The pressure will naturally still be higher at centre line where the ridges 51 will create a locally increased pressure.

(18) It is to be understood that the ridge 51 protruding from the plastic member 19 on each side of the cutting groove can be arranged over or between the active surface 25, 26 depending on the application. The pressure pads having arced convex contact surfaces 53 where the greatest height of the convex shape, in the direction towards the sealing jaw, of each of the pressure pads, are arranged to meet the ridges 51 on opposite sides of the package material (not shown in FIG. 2). The arced convex contact surfaces 53 are thus placed to align with the ridge 51.

(19) It is understood that other variations in the present invention are contemplated and in some instances, some features of the invention may be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly in a manner consistent with the scope of the invention.