Improvements to heat sealing jaws

Abstract

A sealing jaw assembly for impulse sealing heat sealable materials, the jaw assembly comprising an elongate jaw body, an elongate jaw cover and a sealing band. The elongate jaw body having a base for abutting with a press and a stem comprising a proximal region adjacent the base, the stem extending from the proximal end to a distal end and comprising side walls between the proximal and distal ends. The elongate jaw cover for mounting on the elongate jaw body and for contacting the heat sealable materials during impulse sealing. The sealing band supported at the distal end of the jaw body for providing heat to the jaw cover and heat sealable material. The stem comprises heat insulating regions adjacent the side walls to inhibit heat transfer to the jaw cover.

Description

Improvements to heat sealing jaws

[0001] This document claims priority to Australian patent application no 2024902515 filed on 13 August 2024, the contents of which are hereby incorporated by reference in their entirety.Technical Field

[0002] The present disclosure relates generally to sealing heat sealable material, and more particularly to a heat sealing jaw assembly.Background

[0003] Heat sealing jaws seal heat sealable material together, along seams. With the heat sealing process, pockets can be formed: whether of insulation, or of packaging, or other forms.

[0004] To seal heat sealable material layers together, a portion, usually linear, of the layers, is located between an active and a passive jaw bar, or two active jaw bars. There may be a pre-compression phase where the jaws press the heat sealable material layers along the line, without sealing. Then, a controlled heat source is applied through one or more of the active jaw bars, while pressing the layers together with the one or more jaw bars.

[0005] Good sealing depends on equal and even heating and contact between the jaws for the full length of the jaws.

[0006] Some materials demand rapid cooling and others demand slower cooling. Different materials do require different heating and cooling and pressing control regimes.

[0007] With some jaw designs, even with good heating and cooling control, the heating strip bunches up under the impulse heating and causes uneven sealing.

[0008] Sometimes it is a heating strip cover over the jaw that also bunches.

[0009] Some known jaw designs do not allow sufficient jaw closure pressures which can be desirable for certain heat sealable materials.

[0010] Some known jaw designs provide only a thin finished seam, which does not allow even compression of the heat sealable material across a width of a jaw body. Furthermore, some jaw designs only provide a seam which is less than 50% of a jaw width.

[0011] Some jaws are unsuitable for use with some materials, such as IXPE, since the seam they provide is not as wide as the jaw body and pre-compression width.

[0012] Some jaw designs use glass reinforced TEFLON tape jaw covers, which can burn and bunch or ripple.

[0013] Heat flow between various parts of the jaw assembly in known jaw designs is haphazard, making it difficult to control heat in the seal contact faces.

[0014] Some designs cause a cut line to the heat sealable films when sealing & joining IXPE laminated blank (film / foam / film).

[0015] Some designs of sealing jaw cannot be used in wet environments and with wet fill products.

[0016] The present disclosure seeks to provide a new sealing jaw that substantially ameliorates one or more of the abovementioned disadvantages.Summary of the Disclosure

[0017] Broadly, the present technology seeks to provide a sealing jaw assembly configured to provide a plurality of different and controlled temperature zones disposed throughout different jaw assembly components.

[0018] In accordance with a first aspect of the invention, there is provided a sealing jaw assembly for impulse sealing heat sealable materials, the sealing jaw assembly comprising: an elongate jaw body comprising: a base for abutting with a press; and a stem comprising a proximal region adjacent the base, the stem extending from the proximal end to a distal end and comprising side walls between the proximal and distal ends,an elongate jaw cover for mounting on the elongate jaw body and for contacting the heat sealable materials during impulse sealing; a sealing band supported at the distal end of the jaw body for providing heat to the jaw cover and heat sealable material, and wherein the stem comprises heat insulating regions adjacent the side walls to inhibit heat transfer to the jaw cover.

[0019] The sealing jaw body may be formed from materials that provide controlled thermal and electrical conductivity. The jaw body may be made from a low thermal conductive material to reduce heat loss or transfer, preferably from a low thermal and non-electrical conductive material.

[0020] The heat sealing jaw body may be formed from a metal and / or ceramic and / or a composite. The heat sealing jaw body may be formed from a metal and / or ceramic and / or a composite which is coated to provide low thermal and electrical conductivity.

[0021] In an embodiment the heat sealing jaw body is formed of glass fibre reinforced resin such as a high strength glass reinforced epoxy resin.

[0022] In an embodiment the heat sealing jaw body is an impulse sealing jaw, with a sealing band configured to be electrically energised or heated by conduction. The sealing band may be formed from a metallic material, such as stainless steel, nickel, or of an alloy thereof. For example, the sealing band may be formed from a nickel alloy such as nichrome (a nickel-chromium alloy), a stainless steel, or Alloy-20 (a nickel-iron-chromium alloy), The sealing band may be formed from a substrate coated or plated with a metallic material or an alloy thereof, such as nickel, coppernickel, graphite or carbon-based coatings, silver, or the like.

[0023] The sealing band may be coated to provide additional electrical isolation and facilitate smooth expansion / contraction between the sealing band and the jaw cover. The sealing band may be coated with Teflon. The arrangement may reduce sealing band expansion due to the rapid heat transfer to the sealing jaw cover, mitigating the current industry need of matching sealing jaw length to product seal length.

[0024] In an embodiment the heat sealing jaw body is heated by controlling the temperature of a working fluid in galleries disposed inside the jaw.

[0025] A portion of the heat sealing jaw, being a jaw cover, may be cooled by controlling the temperature of a working fluid disposed in the galleries inside the jaw body.

[0026] In embodiments, the elongate jaw cover comprises: an elongate base portion for locating on the jaw body adjacent the proximal portion of the stem of the jaw body; an elongate hollow sheath extending from the base portion, the elongate hollow sheath for receiving the stem of the jaw body and comprising a substantially flat end for contacting a heat sealable material for sealing.

[0027] The heat sealable material may comprise at least one layer. The heat sealable material may be a multi-layer sheet material. The heat sealable material may comprise a polymer sheet material laminated to a surface of an insulation material such as a foam material. The heat sealable material may comprise an insulation layer sandwiched between outer layers of a polymer sheet material. The polymer sheet material may be a flexible material such as polyethylene, polypropylene, or the like. The polymer sheet material may be provided with a reflective coating or layer, an antimicrobial coating or layer, or the like. The insulation material may comprise a foam material, such as a closed or open cell foam material, a cross-linked foam material, or any suitable combination thereof.

[0028] In an embodiment the jaw cover is extruded in a single unified piece from a thermally conductive material. The thermally conductive material may enable rapid heat transfer from the sealing band through the cover to the material being sealed. The thermally conductive material may be aluminium or aluminium alloy, preferably the aluminium is a high strength aluminium, such as 6000 series or 7000 series. The jaw cover may be an extruded aluminium.

[0029] The jaw cover may act as a heat sink drawing heat over the full length of the sealing band irrespective of the width of the material being sealed. The jaw cover may reduce the physical and thermal stresses caused by repeated heating and cooling of the sealing band, reducing the risk of the sealing band breaking. In particular, the jaw cover may prevent portions of the sealing band longer than the width of the material being sealed or not in contact with the work piece from beingoverheated and damaged. The jaw cover may allow a long jaw to be used on any smaller seal length formats.

[0030] In an embodiment the elongate base portion of the jaw cover includes one or more side bodies for drawing heat from the sheath. The side bodies may include galleries in fluid communication with a working fluid. The side bodies may be a cooling system, such as a cooler or a manifold, the working fluid passing through the galleries to draw heat from the sheath. The side bodies may be a water-cooled manifold. The walls of the sheath may be cooled via the cooling system providing controlled temperature zones in the region being sealed.

[0031] In an embodiment, additional heat insulating regions can be located on the side bodies. The insulating regions may be located on an outer side of the side bodies. The heat insulating regions may include channels or recesses located on the surface of the side bodies to provide an air gap between the side bodies and an adjacent clamp when present. The insulating regions configured to reduce heat transfer to and from the clamp. The insulating region may include a heat insulating material on the surface of the side bodies and / or in the channels when present.

[0032] In an embodiment the sheath includes a very thin distal flat end for rapid heat transfer from the heated sealing jaw body.

[0033] In an embodiment the sheath includes a distal flat end for rapid heat transfer from a heated sealing band. The distal flat end of the sheath may form a sealing contact face. The distal flat end of the sheath may be machined down to a minimum thickness (-200 micron). The thin sealing face of the jaw cover may allow rapid heat transfer from the sealing band, promoting fast sealing. The sealing contact face heated by the sealing band can provide a controlled temperature zone in the jaw assembly.

[0034] The sealing surface may be substantially planar, facilitating even compression of the sheet material across the full width of the jaw body. The seal width may be adjusted by temperature and dwell time to 100% of the jaw width, unlike conventional systems where the seal width may be less than the jaw width, often less than 50% of the jaw width, The seal width can be indexed to a pre-compression width.

[0035] The distal flat end of the sheath may have a thinner wall than the side walls of the sheath. The thinner distal wall may provide faster thermal energy transfer thanthe thicker side walls. The thermal energy may transfer from the hotter regions of the sheath (heated by the sealing band) to the cooler areas (cooled by the side bodies). In use, providing the sheath with a thinner distal wall heated by the sealing band and thicker side walls cooled by a cooling system in the side bodies may provide a temperature gradient across the jaw cover and thereby on the surface of the sheet material being sealed and joined.

[0036] In an embodiment the sheath and / or the base of the jaw cover and / or sealing band and / or jaw body flat end contact face are coated in an electrically insulating material. The sealing jaw cover may be heat treated / tempered after machining. The sealing jaw cover may be surface treated after manufacture (e.g. hard anodised, micro arc oxidation or coated) to provide electrical isolation from the electrically energised sealing band. In an embodiment, the sealing jaw cover may be treated using micro arc oxidation.

[0037] The jaw cover may be mounted on the jaw body. In some embodiments, lower surfaces of the jaw cover abut upper surfaces of the base of the jaw body. In other embodiments there may be a gap or void between the jaw cover and the base of the jaw body. The voids may allow the jaw cover to expand / flex under heat sealing / compression force. Further, the void provides clearance for the clamping plate bolts to travel through the clamping plates to engage with the jaw body.

[0038] In an embodiment the jaw body includes a flat distal end.

[0039] In an embodiment the jaw body stem includes a heating / cooling zone. The heating / cooling zone may be preferably located in the distal end of the stem. The heating / cooling zone in the jaw body stem can provide a controlled temperature zone in the jaw assembly.

[0040] In an embodiment the heating / cooling zone includes galleries for receiving a working fluid. The working fluid may be circulated heating fluid, such as hot water, polyol, oil, etc. or may be a circulated cooling fluid, such as air, water, polyol, etc.

[0041] In an embodiment the working fluid is heated or cooled to maintain a heating zone in the jaw body of about 50 degrees Celsius to about 100 degrees Celsius, of about 60 degrees Celsius to about 90 degrees Celsius, or about 65 degrees Celsius to 80 degrees Celsius for impulse sealing, and of about 80 degrees Celsius to about 200 degrees Celsius, of about 100 degrees Celsius to about 190 degrees Celsius, orabout 110 degrees Celsius to 180 degrees Celsius for permanent heating jaw sealing.

[0042] In an embodiment the cooling zone is maintained by a working fluid in galleries in a jaw cover, of about 10 degrees Celsius to about 50 degrees Celsius, of about 20 degrees Celsius to about 40 degrees Celsius, or of about 25 degrees Celsius to about 35 degrees Celsius.

[0043] In an embodiment the galleries are in fluid communication with a heat exchanger and a heating and / or cooling fluid system.

[0044] In an embodiment there is provided a sealing band electrical insulator for mounting between the heating sealing band and the distal end of the jaw body. The insulator acting to electrically insulate the sealing band from the jaw body. The insulator may inhibit heat transfer from the jaw body to the jaw cover or vice versa.

[0045] The insulator may resist rapid fluctuations in temperature. During the operational warm up or pre-heating stage, the jaw body, insulator, sealing band and jaw cover thin distal flat end will reach a relatively uniform temp as per the set temperature. During sealing, the sealing band temperature can be raised to the Required Seal Set Temp by introduction of an electrical current into the sealing band.

[0046] A controller may be used to control the heating and cooling of the heat sealing element during impulse sealing. The controller may monitor and control the electrical current and voltage supplied to the heat sealing band, to ensure a consistent and repeatable weld seam quality.

[0047] In an embodiment the sealing band insulator includes a recessed channel for receiving the sealing band. The recessed channel can extend along the longitudinal axis of the jaw body.

[0048] In an embodiment the recessed channel is formed between two shoulders, such as a pair of parallel flanges, located along the outer edges of the insulator. The shoulders provide support to the jaw cover so that the jaw cover extends across the shoulders without touching. The shoulders can absorb heat from the sealing cover promoting higher temperatures in the centre of the jaw cover and lower temperatures along the outside edges promoting different temperature zones and mitigating the formation of cut lines or weakening of the sheet material along the edges of the seal. In addition, the cooler outside edges of the band (and therefore the outside edges ofthe jaw) may reduce or prevent heat transfer to the sheet material preventing softening of the sheet material. This may prevent expansion at the edges of the seals caused by rapidly expanding heated foam cell structure. The cooler outside edges may avoid zipper failures, that is where the seals are well secured, but the container formed from the sheet material is weakened along the seals.

[0049] In an embodiment the sealing band fits in the recessed channel so that its upper surface is flush with upper surfaces of the shoulders of the sealing band insulator.

[0050] In an embodiment there are one or more clamp assemblies provided to clamp the jaw cover to the jaw body. The clamp assemblies clamp the jaw body and the jaw cover together such that the jaw body and the jaw cover abut one another over selected abutting portions. Tightening of the clamp onto the jaw assembly generates a clamp force and friction grip between the jaw cover and the jaw body that resists movement of the jaw cover and jaw body relative to one another.

[0051] In an embodiment the clamp assemblies include clamping plates. The clamping plates configured to be fastened to the side of the sealing jaw assembly.

[0052] The dimensions of the clamping plate may be substantially similar to a side profile of the jaw assembly such that the clamping force is applied substantially evenly across the jaw assembly. The height of the clamping plates may be at least the same as the combined height of the base of the jaw body and the side body of the jaw cover. In embodiments where a gap or void is located between the jaw cover and the jaw body, the height of the clamping plates may be the substantially the same as the combined height of the base, the gap and the side body.

[0053] In embodiments, the clamping plates may be provided with a plurality of apertures spaced apart along the length of the clamping plate, The apertures may be configured to receive a mechanical fastener (such as screws, bolts, pins, rivets or the like) therethrough. The fasteners may be clamping bolts.

[0054] The fasteners may extend through apertures located in the clamping plates to engage with the jaw cover and / or jaw body. Tightening of the fasteners may generate the clamping force on the jaw assembly. The fasteners may removably connect the jaw cover and the jaw body to one another.

[0055] In embodiments where a gap or void is located between the jaw cover and the jaw body, the fasteners may pass through the void to engage with the jaw body, for example with the base of the jaw body. In other embodiments, the fasteners may pass through the jaw body to engage with the opposing clamping plate such that the fastener extends from one side of the jaw assembly to the other. The fastener may be provided with a nut or a locking pin to tighten the fastener and generate a clamping force on the jaw assembly.

[0056] In embodiments where the jaw cover and jaw body abut one another (i.e. there is no gap or void), the fasteners may engage with the jaw cover, for example with a side body of the jaw cover.

[0057] The jaw body may have a plurality of apertures spaced apart along the length of the base. The plurality of apertures in the jaw body may be spaced apart such that they substantially align with the plurality of apertures located in the clamping plates. The apertures in the jaw body may be configured to receive a portion of the fasteners therein. The apertures may be configured to allow the fasteners to pass entirely through the jaw body from one side to the other side.

[0058] In an embodiment the jaw body includes an elongate body, and in cross section including a base for being contacted by a press, and a stem extending therefrom.

[0059] In an embodiment the stem includes a distal end for supporting the jaw cover providing heat to the jaw cover and heat sealable material. The stem is elongate in cross section to rapidly facilitate heat transfer from the jaw body adjacent the jaw cover.

[0060] The stem of the jaw body may comprise one or more heat insulating regions to inhibit heat transfer to the jaw cover. The heat insulating regions may comprise air insulation gaps. The heat insulating regions may include channels or recesses located on the surface of the jaw body to provide an air gap between the jaw body and the jaw cover. In some embodiments a plurality of heat insulating regions may be located on the surface of the jaw body.

[0061] The heat insulating regions may comprise a heat insulating material located on the surface of the jaw body. The insulating material may be located in the channels or recesses located on the surface of the jaw body.io

[0062] In one embodiment the jaw body and jaw cover each include heat insulating regions disposed adjacent the selected abutting portions.

[0063] The sealing jaw assembly according to embodiments of the invention provides a number of different controlled temperature zones, including: Zone 1 : Jaw body is heated / cooled by a circulating working fluid; Zone 2: The sealing surface of the jaw cover is preheated by the sealing band; and Zone 3: The sealing jaw cover side walls are cooled to a preset temperature maintaining temperate zones. In addition, the sealing jaw assembly according to embodiments of the invention comprises a plurality of recessed channels along the outer surface of the sealing jaw body to limit heat transfer between the jaw cover and the jaw body, the channels forming air insulation gaps. Advantageously, different zones of the sealing jaw assembly can operate at different temperature settings providing efficient heating and cooling differentials. The sealing jaw assembly may be particularly useful when sealing and joining high thermal resistive materials such as IXPE laminated sheet materials (film / foam / film) requiring dual (top and bottom) sealing jaw applications. In addition, the sealing assembly according to embodiments removes the high cost / wear component of glass reinforced TEFLON tape covers / sealing bands, avoiding the problematic ripple effect on TEFLON / sealing band and burning of the tape which results from high compressive sealing pressures and use of sealing jaws longer than the width of the material being sealed.Brief Description of Drawings

[0064] Embodiments of the invention will now be described with reference to the accompanying drawings which are not drawn to scale and which are exemplary only and in which:

[0065] Figure 1 is a perspective view of a prior art TEFLON tape-covered impulse jaw sealing assembly showing bunching and rippling;

[0066] Figure 2 is a cross-section isometric view of a jaw assembly of an embodiment of the present disclosure;

[0067] Figure 3 is a cross-section view of an embodiment of jaw cover; and

[0068] Figure 4 is a cross-section isometric view of a jaw cover mounted on an elongate jaw body according to an embodiment of the present disclosure.Detailed Description

[0069] To provide background understanding, reference is made to a previously known impulse sealer 2 shown in Figure 1. This Figure shows an elongate jaw body 5, and that which can be seen is a PTFE tape jaw cover 6. The jaw cover 6 can be seen as burnt and buckled, which leads to poor sealing and leaks.

[0070] One of the features of the embodiments of the instant technology shown in Figures 2-4, is that a jaw cover 30 is formed from a single block of material, extruded and / or machined and / or additively formed. The unified nature of the jaw cover 30, among its other features described below, reduces or substantially eliminates buckling of the cover under the intense and rapidly changing heating and cooling process associated with heat sealing using a sealing band and / or heated jaw body directly underneath a flat cover sheath tip 36.

[0071] Other features of the embodiments shown that may be useful and advantageous in reducing buckling of a distal end 36 of the jaw cover 30 under impulse and / or jaw body heat load are different heat zones 12,14 spaced apart and / or spaced around in different parts of a cross section of the jaw assembly. Galleries allow fluid through these areas for heat transfer. These are described in detail below.

[0072] To maintain the different heat zones in the various spaces around the cross section of the jaw assembly there are also provided insulating zones between the heat zones. The insulating zones 27,28 are gaps and recesses located on a surface of the jaw body.

[0073] To further maintain the different heat zones, a jaw body 20 is formed of insulating material such as fibre reinforced epoxy resin and / or from a metal and / or ceramic and / or a composite which is coated to provide low thermal and electrical conductivity. The fibre reinforced resin also is very strong and can withstand repeated heavy pressing.

[0074] The shape of the jaw body also assists heat flow in that the body 20 includes a base 21 and a stem 22 which extends from proximal end 23 to distal end 24. This reduces material between the different heating zones 12 and 14, to inhibit heat transfer therebetween, since one of which is held at a higher temperature and the other is held at a lower temperature.

[0075] There is also a flat distal end 36 with good heat transfer facilitated by a thin, flat sheath end 36, under which is a heat seal band 70 set flush in a recess 75 of an insulator 40 at the distal end 24 or simply by a heated jaw body 20.

[0076] Referring to Figures 2 and 3 there is shown an impulse sealing jaw assembly generally indicated at 10, configured to provide a plurality of different heat zones 12, 14 disposed throughout different jaw assembly components. The heat zone 12 is a cooling zone disposed in an elongate jaw cover 30 and heat zone 14 is a heating zone disposed inside an elongate jaw body 20.

[0077] There is also shown in Figure 2 an elongate impulse jaw body 20 formed of a material that is low in thermal and electrical conductivity. The impulse jaw body is formed from metal and / or ceramic and / or composite which can be coated to provide low thermal and electrical conductivity and includes a base 21 for abutting with a press (not shown) and a stem 22 including a proximal end 23 adjacent the base 21, the stem 22 extending from the proximal end 23 to a distal end 24 and including side walls 25,26 between the proximal end 21 and the distal end 24.

[0078] The stem 22 is for mounting a jaw cover 30 thereon and the stem 22 further includes heat insulating regions 27, 28 located on the side walls 25,26 to inhibit heat transfer to the jaw cover 30. The heat insulating regions may be air gap insulation formed by channels along the longitudinal axis of the stem adjacent the side walls of the sheath. The heat insulating regions may be a heat insulator located between the stem and adjacent side walls of the sheath.

[0079] The elongate jaw cover 30 is configured to locate on the sealing jaw body 20 and includes an elongate base portion 31 for locating on the jaw body 20 adjacent the proximal portion 23 of the stem 22 of the jaw body 20. There is also an elongate hollow sheath 35 extending from the base portion 31 , the elongate hollow sheath 35 being for receiving the distal end 24 of the stem 22 of the jaw body 20 and thatsheath 35 also features a substantially flat end 36 for contacting a heat sealable material (not shown) for sealing.

[0080] The base portion 31 of the jaw cover 30 include one or more side bodies 33, 34 for drawing heat from the sheath. The side bodies 33,34 include coolers 37 which include galleries 38 in fluid communication with cooling fluid.

[0081] The side bodies 33,34 abut a lower region of the stem, insulating regions 28 at the proximal end 23 of the stem are located between the stem and the side bodies. The sheath 35 abuts the side walls of the stem, insulating regions 27 at the distal end 24 of the stem are located between the stem and the sheath. The insulating regions 27,28 include channels or recesses located on a surface of the jaw body 20 to provide an air gap between the jaw body and the jaw cover 30 suitable for an air purge providing physical separation reducing heat transfer cooling the sheath. Also, there are insulating regions 29 of a similar structure on the outer side of the side bodies to reduce heat transfer to and from a clamp 80.

[0082] There is provided a sealing band insulator 40 for mounting between the heating band 70 and the distal end 24 of the jaw body. The sealing band insulator 40 providing electrical insulation and resistance to rapid temperature change. The sealing band insulator 40 includes a recessed channel 75 for receiving the sealing band 70. The sealing band 70 fits in the recessed channel 75 so that its upper surface is flush with upper surfaces of shoulders of the sealing band insulator 40 for good heat transfer to the sheath end 36. Setting the sealing band 70 within the recess 75 of the insulator 40 may restrict sideways movement of the sealing band preventing it from contacting a side wall of the sealing cover 30 and causing an electrical short circuit.

[0083] There are clamps 80 provided to clamp the jaw cover 30 to the jaw body 20. The clamps 80 include clamping plates 82 having similar dimensions to the combined heights of the base 21 and side bodies 33,34 and void 50 and the length of the jaw cover 30 / jaw body 20. The clamping plates 82 have a plurality of apertures spaced apart along the length of the plate, the apertures configured to receive a fastener 84 such as a clamping bolt therethrough. The jaw body 20 may have a plurality of apertures (144 in Figure 4) spaced apart along a surface thereof, the apertures in the jaw body aligned with the apertures in the clamping plates and configured to receivea portion of the clamping bolt 84 therein. The clamping bolt may pass entirely through the jaw body to engage with apertures in the opposing clamping plate.

[0084] Voids 50 located between the jaw cover 30 and base 21 of jaw body 20 provide clearance for the clamping plate bolts to travel through, pulling the clamping plates 82 together holding the jaw cover in place.

[0085] The jaw cover 30 is formed from a unified body, and this may be useful for inhibiting rippling and buckling. Even though there is a heat source (a sealing band 40) directly underneath the jaw cover sheath end 36, and that end 36 is thinned down to about 200 microns, the unified nature of the sheath and cover contributes to that end 36 being inhibited from buckling and rippling. The unified jaw cover 36 is extruded from aluminium, coated in an electrically insulating material such as hard anodising, micro arc).

[0086] Referring to Figure 4, there is illustrated a jaw body 120 having a portion of a non-anodised sealing jaw cover 130A and a portion of an anodised sealing jaw cover 130B mounted thereon. Ports 142 connectable to the galleries located in the side bodies 133,134 of the jaw cover enable a cooling fluid (such as air, water, etc.) to be passed through the galleries for cooling the jaw cover.

[0087] A plurality of apertures 144 are spaced apart along the length of the proximal portion of the stem 122 of the jaw body 120. When assembled, a clamping plate bolt may first pass through aperture (84 in Figure 2) in a first clamping plate (82 in Figure 2) and into the void (50 in Figure 2) located between the jaw cover and the base of the jaw body. The clamping plate bolt is passed through an aperture 144 in the jaw body 120 and into an aperture located in the opposing second clamping plate (82 in Figure 2). A nut is tightened on the end of the clamping plate bolt allowing the clamping plates to clamp the jaw cover and jaw body together.IN OPERATION

[0088] To ready the jaw assembly 10 for sealing, the heat zone 14 of the jaw body 20 is measured by a temperature sensor at the distal end 24 and is controlled by the flow of working fluid in the gallery 39 to be at about 40°C to 60°C. A working fluid passing through galleries 38 in the side bodies 33,34 at about 30°C assists in controlling the temperature of the sheath 35.

[0089] Then, to conduct a sealing operation by impulse sealing, the jaw body 20 is pressed against another like jaw body, distal end to distal end, and the temperature of the jaw body 20 is elevated in two stages. First there is a pre-heating stage which provides a pre heat temperature of about 80°C to 90°C, then the sealing band 70 is electrically energised to a sealing temp of about 200°C for a few seconds. A controller can monitor and control the electrical current and voltage supplied to the sealing band during impulse sealing, to ensure a consistent and repeatable weld seam quality.

[0090] Once impulse sealing is complete the injection of electrical energy into the sealing band 70 stops and the thin distal flat end 36 then rapidly cools to the standby temperature which is as mentioned, about 40°C to 60°C.

[0091] The sealing cycle is now complete, and the jaws are opened.

[0092] It will be understood to persons skilled in the art of the disclosure that many modifications may be made without departing from the spirit and scope of the disclosure.

[0093] It is to be understood that any prior art publication referred to herein does not constitute an admission that the publication forms part of the common general knowledge in the art.

[0094] In the claims which follow and in the preceding description of the disclosure, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the disclosure.

Claims

Claims1. A sealing jaw assembly for impulse sealing heat sealable materials, the sealing jaw assembly comprising: an elongate jaw body comprising: a base for abutting with a press; and a stem comprising a proximal region adjacent the base, the stem extending from the proximal end to a distal end and comprising side walls between the proximal and distal ends, an elongate jaw cover for mounting on the elongate jaw body and for contacting the heat sealable materials during impulse sealing; a sealing band supported at the distal end of the jaw body for providing heat to the jaw cover and heat sealable material, and wherein the stem includes heat insulating regions adjacent the side walls to inhibit heat transfer to the jaw cover.

2. The sealing jaw assembly in accordance with claim 1 , wherein the jaw body includes an insulator located between the sealing band and the distal end of the jaw body.

3. The sealing jaw assembly in accordance with claim 2, wherein the insulator includes a recessed channel and wherein the sealing band is located in the recessed channel.

4. The sealing jaw assembly in accordance with any one of the preceding claims, wherein the jaw body is made of a low thermal and non-electrical conductive material, preferably wherein the jaw body is made of a fibre-reinforced epoxy resin material.

5. The sealing jaw assembly in accordance with any one of the preceding claims, further comprising one or more galleries disposed within the jaw body, wherein the temperature of the jaw body is controlled by the temperature of a working fluid circulating through at least one of the galleries.

6. The sealing jaw assembly in accordance with claim 5, wherein one of the one or more galleries is located in the distal end of the stem.

7. The sealing jaw assembly in accordance with any one of the preceding claims, wherein the sealing band is coated in an electrical insulating material.

8. The sealing jaw assembly according to any one of the preceding claims, wherein the elongate jaw cover comprises: an elongate base portion for locating on the jaw body adjacent the proximal portion of the stem of the jaw body; an elongate hollow sheath extending from the base portion, the elongate hollow sheath for receiving the stem of the jaw body and comprising a substantially flat end for contacting a heat sealable material for sealing.

9. The sealing jaw assembly according to any one of the preceding claims, wherein the elongate jaw cover is extruded in a single unified piece from a thermally conductive material, preferably wherein the elongate jaw cover is extruded from aluminium.

10. The sealing jaw assembly according to claim 8 or claim 9, wherein the base of the jaw cover includes one or more side bodies for drawing heat from the sheath.

11. The sealing jaw assembly according to claim 10, further including a gallery disposed in each of the one or more side bodies, wherein the temperature of the side bodies is controlled by the temperature of a working fluid circulating through the gallery.

12. The sealing jaw assembly according to any one of the preceding claims, wherein the heat insulating regions include channels or recesses located on a surface of the jaw body to provide an air gap between the jaw body and the jaw cover.

13. The sealing jaw assembly according to any one of the preceding claims, wherein one or more clamp assemblies clamp the jaw body and the jaw cover together,14. The sealing jaw assembly according to claim 13, wherein additional heat insulating regions are located on an outer side of the side bodies to reduce heat transfer to and from the one or more clamp assemblies.

15. The sealing jaw assembly according to claim 13 or claim 14, wherein the one or more clamp assemblies include a clamping plate configured to be fastened to the side of the sealing jaw assembly.

16. The sealing jaw assembly according to claim 15, wherein the clamping plate comprises a plurality of apertures spaced along the length of the plate, the apertures configured to receive a clamping bolt therethrough.

17. The sealing jaw assembly according to any one of claims 8 to 16, wherein the sheath includes a thin distal flat end for rapid heat transfer from the sealing band or heated jaw body to the jaw cover.

18. The sealing jaw assembly according to any one of claims 8 to 17, wherein the sheath and / or the base of the jaw cover are coated in an electrically insulating material.

19. The sealing jaw assembly according to any one of claims 8 to 18, wherein the jaw body includes a flat distal end.

20. The sealing jaw assembly according to any one of the preceding claims, wherein a gap is located between the jaw cover and the base of the jaw body.

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