GB2241469A - Laminating machines - Google Patents

Abstract

A method and apparatus for bonding a protective film 15 onto a substrate sheet 75, for example a data bearing document. The machine includes a frame 7 for lifting and supporting magazine rolls 8, 9 of film in operative positions, pivotable infrared heaters 12 for heating an adhesive face of the film to bonding temperature, heated nip rollers 20 and subsequent pressure rollers 22, 25, 26 to provide bonding pressure, wheels 27 to press film into a longitudinal gap between substrate sheets, and cooling rollers 23, 24 which may be pivoted to bend the laminate path for straightening any curl produced by bonding. A guillotine separates the sheets of substrate transversely after bonding. <IMAGE>

Description

LAMINATING MACHINES This invention relates to machines for laminating a protective film onto a substrate such as a data-bearing document. For example, paper menus or timetables may be laminated with transparent protective film on one or both faces to extend their life and improve their appearance.

This treatment can also be used to preserve old documents.

A tough abrasion resistant coating can also extend the life of fairly sturdy items, such as, plastic bus-passes, signs, etc.

A commonly used film comprises a tough flexible sheet, usually of polyester, which is coated on one face with a bonding material which is to serve as an adhesive, usually polyethylene. This bonding layer must be heated and pressed onto the substrate to achieve adhesion. Film may be bonded onto one or both faces of a substrate and in the latter case the films may be bonded together around the edges of the substrate sheet to form an encapsulate laminated material.

At present, machines are often used to carry out the laminating process (hereinafter referred to as machines of the type described). One common problem with known laminating machines is in achieving even heating of the film to a specific suitable temperature which will ensure good bonding over the whole area.

Typically the film is heated in either of two ways.

Heat may be applied to the polyester or other outer layer so that heat passes by conduction to the polyethylene or other adhesive layer. This is usually achieved by contact of the polyester face with rollers heated by rod heaters.

This type of heater often produces hot/cold spots, and thus does not heat the film evenly. Other heating methods include the use of hot oil heated rollers, solid rubber rollers with electric heater elements moulded inside, and hot shoes over which the film is passed. In every case, if the machine is stopped, there will be residual heat which may damage the film which is stationary at that position.

Since bonding is impaired due to uneven or insufficient heating which may result from the above method, it has been necessary to use relatively slow laminating speeds.

Alternatively, the bonding side of the film may be heated, usually by use of radiant heaters and not by contact since the bonding layer must be brought to or close to, its melting point. Again, if the machine is stopped, residual heat from the heaters may damage or set fire to the stationary film.

According to a first aspect of the present invention there is provided a laminating machine for bonding film onto a substrate, having a radiant heater for heating a bonding layer of the film, movable between a position in which heat is directed towards a path followed by the film before bonding, and a position in which heat is directed away from the film path. Preferably, the heater is of the infrared type, and there are preferably a plurality of heaters each provided with a reflector jacket to direct the heat. These jackets may include means for passing air, which may be chilled, through the reflector jacket to assist cooling of the heaters, for example, when the machine is stopped. Preferably, each heater and its associated reflector is movable by pivoting to direct the heat either towards or away from the film path.

Thus, it is possible to remove applied heat from the film, for example, when the machine is stopped. This means that more powerful heaters may be used. For example, the heaters may be of the medium wave infrared type, and may be positioned very close to the film for heating, for example 3mm from the film. Thus, the film is heated rapidly, and the laminating process may run faster. Also to increase the amount of heat applied to the film, a further reflector may be mounted on an opposed reflector jacket provided on the opposite side of the film path, to reflect heat from the heaters back onto the film. Also residual heat may escape into the jacket, for example, when the machine is stopped and the jacket may also include a tube to carry cooling air.The opposed reflector jacket may be positioned very close to the film in use of the machine, and thus it may be movable away from the film path to facilitate loading of the film into the film path.

The film preferably comprises a protective web coated on one face with a bonding material. In the use of such a film it is preferably the bonding face which faces the radiant heater.

Another serious difficulty with the laminating process is caused by the fact that the heated film shrinks on cooling after bonding, and thus the laminate tends to curl. The problem is worse when the substrate is to be covered with film on one side only. The laminate then tends to curl with the film on the inside.

According to a second aspect of the present invention there is provided a machine of the type described, having rollers mounted on either side of a laminate path in staggered formation, a first roller, which is on one side of the laminate path being movable towards a roller on the other side of the laminate path such that the laminate path is deviated from a straight line configuration between the rollers.

Preferably the rollers are mounted in pairs on supporting members, and movement of the roller is preferably a pivotal movement of one pair about one end of the supporting member, such that one roller moves towards a gap between each roller of an opposite pair causing the laminate to follow a serpentine path.

Curling may also occur if uneven tension is applied to the material. It is desirable to create a strong and even tension in the film and the laminate for good bonding.

Present machines have a method of restricting rotation of the magazine roll of film for this purpose. Fixings to hold the shaft ends are mounted directly onto the main frame of the machine, and the shaft ends have mounted on them the necessary restriction to brake the film roll.

However, this method does not maintain constant tension since there is no compensation for the changing diameter of the roll as the film is used. Also, it creates difficulties when loading a magazine roll, as manual rotation of the roll is not easy. Since the rolls of film are placed manually into position, (although on larger machines a hoist may be used) handling problems also limit the weight and diameter of a roll which can be used with such machines.

According to a third aspect of the invention there is provided a mobile frame for use with a laminating machine, and securable thereto provided with shaft holders to support a magazine roll of film, the frame having means to lift the shaft holders to a position corresponding to an operational position of the roll.

Preferably, the frame carries a roll of film to be used with a laminating machine of the type described. The frame may have additional shaft holders for supporting a further magazine roll. The supported rolls may be upper and lower magazine rolls carrying film for bonding onto either face of a substrate sheet.

According to a fourth aspect of the present invention, there is provided a machine of the type described, having a tension roller around which the film passes, and brake means actuable to restricting rotation of the tension roller. By braking the tension roller by a variable amount, a constant tension may be maintained in the film as the magazine roll is used.

Existing machines are adapted either to laminate film onto one side of a substrate material or to laminate film onto both sides. Thus it is necessary to have two machines if both operations are to be performed, which is costly both initially and in terms of space, maintenance etc.

According to a fifth aspect of the present invention, there is provided a machine of the type described having a pair of bonding rollers drivable by drive means, and means to disconnect one roller of the pair from the drive means, brake means being provided to restrict rotation of the one roller.

Film is fed only by a roller which is driven, and thus the machine may be operated to bond film onto one side only of a substrate material. Since rotation of the roller may be restricted on the side of the substrate which has no film, the frictional force created between the substrate and the roller helps reduce the tendency of the laminated material to curl with the film on the inside.

Laminating machines are usually of fixed mechanical construction, which causes difficulties with initially feeding the film through the machine and especially if there is a fault and the web is carried around one of the rollers. The assembly may then have to be dismantled to remove the foul-up and to rethread the machine.

According to a sixth aspect of the present invention, there is provided a machine of the type described, having an upper roll supporting frame and a lower roll supporting frame, which frames are movable with respect to one another. Preferably, they are pivotable about a point at one end of the frames. Thus the material may more easily be loaded or removed from the machine. This can also facilitate the cleaning of adhesive from the rubber covered rollers.

At present, sheets of substrate material are fed into a laminating machine by hand. The position of the trailing edge of a sheet is guessed, and a new sheet is placed in position. Alternatively, the lower film supply may be carried over the rollers ahead of the nip rollers to form a type of conveyor, and the next sheet is placed as near as possible so that a minimum gap is formed between the sheets as the new sheet is carried forwards. Neither of these methods can guarantee a uniform gap which can be cut by a single operation to leave a suitable even edge on both pieces of material.

According to a seventh aspect of the present invention there is provided a machine of the type described having a feed table, sensing means mounted close to a bonding area of the machine which produces a signal when there is no substrate sheet adjacent the sensing means, and drive means actuable to drive a substrate sheet along the feed table towards the machine in response to the signal.

The sensing means may comprise two sensors each mounted on a bar, one on either side of the substrate path.

The upper bar may also serve as abutment means for a substrate sheet placed on top of a lower sheet being drawn into the machine. When the trailing edge of the lower sheet leaves the gap between the sensors, the upper bar may move away to allow the. upper sheet to be driven into the machine. The drive means may comprise a wheel and may be actuable by pivoting the wheel towards the feed table to engage a sheet. It may drive the sheet towards the machine at a speed greater than the speed at which a sheet is drawn into the machine, such that the upper sheet may catch up with the lower sheet to form a predetermined small gap.

The laminating process may be used to laminate a web of film onto a number of widths of substrate material.

For example, there may be four pieces of substrate along the width of the machine.

It may be required to press the film together in the longitudinal gaps between substrate sheets, for example, to produce an encapsulate material. To achieve this, rollers having a low surface hardness have been provided, to which it is necessary to apply a high pressure so that the roller will deform and sufficient pressure will be applied to the gap. This puts the entire width of the material under such high pressure that pressure sensitive laminating materials may be damaged. Also, ridges may be formed in the rollers where they have deformed into the gaps, especially after long runs.

According to an eighth aspect of the present invention there is provided a machine of the type described having a wheel aligned with a longitudinal gap between sheets of substrate material in a laminate web, which wheel presses the film into the gap. Preferably there are two such wheels corresponding to each gap and mounted above and below the gap respectively. Thus a high pressure need be applied only in the area of the gap, and the roller may be made of a harder material.

At present, the method of separating the substrate sheets after lamination is to pass the continuous web to a simple guillotine where it is stopped at a predetermined position so that a blade may be operated to cut the film between sheets. This interferes with the continuous movement of the web from the machine.

According to a ninth aspect of the present invention there is provided a guillotine assembly for use with the laminating machine to cut a web of laminate, the assembly comprising: a mobile clamp frame including means to clamp the web of laminate in response to a signal produced by means for sensing a gap between sheets of substrate material in the laminate; and a blade carrier mounted on the clamp frame and movable with respect to the clamp frame in response to a signal produced by sensing means for sensing the position of the gap; and means to operate a blade mounted on the blade carrier to cut the web.

According to a tenth aspect of the present invention there is provided a method of transversely cutting a moving web of material at a predetermined cutting position comprising the steps of: clamping the web to a clamp frame; moving the frame at the same speed as the web; sensing the cutting position; moving a blade carrier mounted on the clamp frame to the cutting position; and operating a blade mounted on the blade carrier to cut the web.

The moving web may be a laminate web produced by a laminating machine, and the cutting position may be a transverse gap between substrate sheets of the laminate.

Some laminating processes produce a single sided laminate in which the transverse edges of the sheets of substrate overlap slightly in order to reduce the risk of adhesive contacting the rollers.

These sheets have been separated by attempting to slide a knife from one side to the other, or by flicking the overlapping edge of a sheet to break the film, and then tearing the sheets apart by pulling the flicked edge.

According to an eleventh aspect of the present invention, there is provided a guillotine mechanism for use with a laminating machine to separate substrate sheets laminated on one side with a film, the mechanism comprising: means for causing a gap to be formed between an overlapping transverse edge of a substrate sheet, and an overlapped edge of another sheet; first cutting means insertable into the gap; and second cutting means actuable to cooperate with the first cutting means to cut the film transversely between the substrate sheets.

According to a twelfth aspect of the present invention there is provided a method of transversely separating substrate sheets of a single sided laminate produced by a laminating process, the method comprising the steps of: causing a gap to be formed between an overlapping transverse edge of a substrate sheet and an overlapped edge of another sheet; inserting first cutting means into the gap; and cutting the film between the sheets by means of second cutting means cooperating with the first cutting means.

The gap may be formed by causing the path followed by the laminate through the mechanism to be curved. This may be achieved by moving a guide roller towards the laminate path, such that the laminate passes over the guide roller. The mechanism may include drivable inlet and outlet rollers, for driving the laminate through the mechanism. Sensing means may be provided to sense the proximity of the overlapping edge, and to actuate the means to form the gap, for example by pivoting the roller towards the laminate path to engage the laminate. The sensor may also actuate the first cutting means, which may be a rotatable knife, to move to a position in which it may enter the gap produced, for example a position adjacent the guide roller.

After insertion of the rotatable knife, the guide roller may be moved away from the laminate, such that it returns to a straight path, thus rotating the knife, and the laminate may be stopped for example by disconnecting the drive of the inlet and outlet rollers during actuation of the second cutting means, which may be a knife extendible towards the laminate path, and retractable. The outlet rollers may then be driven to discharge the cut laminate, and the rotatable knife may be positioned such that it guides the leading edge of the next laminate sheet towards the outlet rollers.

According to a thirteenth aspect of the present invention there is provided a laminating machine for bonding film onto a substrate document, comprising an upper roller supporting frame and a lower roller supporting frame, the frames being pivotable with respect to one another from a closed operational position to an open position to facilitate loading or removal of material, each frame supporting:: a tension roller around which a web of film is passed, having adjustable braking means actuable to alter the tension in the web of film; a radiant heater provided with a jacketed reflector, which is movable to direct radiant heat onto the film or away from the film; a pressure bonding roller which, in the operational position of the frames, forms a gap with the bonding roller supported on the other portion such that bonding pressure is applied to the film and the substrate material when they pass through the gap; a free-running pressure roller which applies further pressure to the bonded laminate; a driven pressure roller which creates tension in the laminate; and a cooling roller which contacts the laminate to extract heat from it by conduction.

According to a fourteenth aspect of the invention there is provided a method of bonding film onto a substrate, the film comprising a web of protective material provided on one face with a layer of bonding material, the method comprising the steps of: feeding the film web around a brakable tensioning roller and adjusting the braking to maintain a substantial ly constant tension in the film web; feeding the film web past a radiant heater such that the bonding material reaches a bonding temperature; feeding the film web and a substrate material between a pair of driven bonding rollers such that the bonding material contacts the substrate to form a laminate material; feeding the laminate between further driven pressure rollers to apply tension to the laminate, and to cooling rollers to remove heat from the laminate by conduction;; moving the cooling rollers to deviate the path of the laminate when curling of the laminate occurs.

In order that the present invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a diagrammatic side view of a laminating machine according to one embodiment of the invention, Figure 2 is a perspective view of a mobile film roll carrying frame for use with the machine of Figure 1, Figure 3 is a side view of part of the chain drive of the frame shown in Figure 2, Figure 4 is an enlarged view of part of the machine of Figure 1, Figure 5 is an enlarged view showing the ends of the tension rollers in the machine of Figure 1, Figure 6 is a side view of the arrangement shown in Figure 5, Figure 7 is a diagrammatic side view of a single sided guillotine mechanism, Figure 8 is a plan view of the lower nip roller of Figure 4, and the associated drive mechanism, Figure 9 is an enlarged view of another part of the machine of Figure 1, Figure 10 is a part sectional view of a cooling roller for use in the machine of Figure 1, Figures 11 to 13 show various positions of the cooling rollers, in end view, Figures 14 and 15 are diagrammatic side views of the feeding mechanism of the machine, Figure 16 is an enlarged view of the nip rollers, wheels and first pressure rollers, in end view, of the machine of Figure 1, Figure 17 is a side view of the wheels of Figure 16, Figure 18 is a perspective view of a guillotine assembly for use with the laminating machine, Figure 19 is a diagrammatic plan view of a sheet feed system, and Figure 20 is another side view of the machine of Figure 1.

Referring to Figure 1, a laminating machine indicated generally by 1, comprises a main frame 2 on which is mounted a lower roller supporting frame 3 having a perpendicularly extending portion 4 at one end. A substantially symmetrical upper roller supporting frame 5 with a perpendicular portion 6 is pivotally attached to the lower frame 3 so that the machine may be opened for loading or removal of material (Figure 20), by means of an actuating cylinder 17. A mobile frame 7 carries upper and lower film magazine rolls 8,9 of film, the upper roll being lifted by means of a chain drive (Figures 2 and 3). The frame 7 may be positioned adjacent one end of the machine 1 such that the film rolls 8,9 are positioned adjacent the horizontal ends of the portions 4,6. The film 16 passes around tension rollers 10 and 11 and between jacketed radiant heaters 12 and jacket 13.

Substrate material is fed into the gap between pressure rollers 20 known as nip rollers, where bonding of the hot film 16 and the substrate takes place. There may be several sheets of substrate positioned side by side.

The horizontal portions of the roller supporting frames 3,5 carry one pair of free-running pressure rollers 22, and two sets of cooling rollers 23,24 and driven pressure rollers 25,26 between which the laminate 28 passes. The freerunning rollers 22 assist bonding and the driven rollers 25,26 are provided with a speed differential which creates tension in the laminate 28. The cooling rollers 23,24 form staggered pairs such that one roller may be moved into the gap between the opposite pair to control curling of the laminate 28. These rollers 23,24 remove heat from the laminate directly by conduction. The tension in the film facilitates the action of the cooling rollers 23,24.

Wheels 27 are supported just beyond the nip rollers for pressing the film in the longitudinal gaps between pieces of substrate material 75.

A guillotine assembly 30 may be positioned at the other end of the machine 1. This provides means for transversely cutting the laminate web between sheets of substrate material whilst it is moving from the machine 1.

Alternatively, a single side guillotine mechanism may be used for this purpose, in the case of substrate laminated on one side only.

Referring now to Figures 2 and 3, the magazine roll carrying frame 7 is angled and mounted on four wheels 40.

Guide pins 41 engage bushes on the main frame 2 of the machine 1 when the frame 7 is in position. It includes lifting chains 42 on either side with associated chain guards 43. Each chain 42 has a shaft holder 44 into which each end of the shaft 8a of the upper magazine roller 8 can be placed. A lifting motor 45 and an associated control panel 46 are fixed to the frame 7. Shaft holders 47 are provided for accommodating the shaft 9a of lower magazine roll 9, and are fixed to the frame 7.

The laminating film 16 comprises a web of material which may be a protective material, in this case polyester, which is coated on one side with a bonding layer of polyethylene.

Adjacent each roll of film 8,9 are tension rollers 10,11. The tension rollers 10,11 shown in more detail in Figures 5 and 6, are rubber covered. One of the rollers 11 has a braking system comprising a wear-resistant disc 53 mounted on the shaft 54 of the roller 11, and two braking pads 55,56. The first pad 55 is mounted on a pressure unit 58 which is slidably mounted on a fixing 59 attached to the side frame 57. A compressed air inlet 60 provides means to control the position of the unit 58 and thus the braking pressure on the disc 53.

As shown in Figure 4, the jacketed heaters 12 each comprise an infrared heating member 61, a reflector 62 and a cooling jacket 63. Each heater 12 is pivotable about a point 64 which may comprise a tube through which cooling air may be passed. Thus the heater may face.towards the film 16 in operation (solid lines) or away from it (broken lines) for example when the machine is stopped. The opposing reflector jacket 13 is positioned close to the film and also includes a reflector 65. It may be moved away from the film path to facilitate loading of the film (broken lines).

The nip rollers 20, which are substantially identical, have a central rod heater 72 within a steel tube 73 which is covered with an outer layer 74 of a material such as silicone rubber (Figure 4).

The nip rollers 20 are provided with means to drive them at the same speed to produce a product laminated on both sides. For bonding the film 16 onto one side only of the substrate 75, the lower nip roller 20b may be disconnected from the drive system and a brake may be applied to it. Referring to Figure 8, the lower nip roller shaft 86 is connected via a chain 87 drive to a driven shaft 88.

The driven shaft 68 may be selectively connected to a drive shaft 81 by movable gear wheels 82. Movement of the gear wheels 82 is actuated by an air cylinder 83. A pressure unit 84 is provided to apply variable pressure to a braking disc 85 mounted on then nip roller shaft 86.

Wheels 27 are positioned between the nip rollers 20a,b and the free running pressure rollers 22 and are aligned with the gaps between adjacent sheets of substrate 75 to create pressure about the gap area. Referring to Figures 16 and 17 the wheels 27 are mounted on support arms 89, and are of soft rubber to deform into the gap.

The cooling rollers 23,24 are mounted in pairs above and below the laminate path, in a staggered formation. Referring to Figure 10, each cooling roller 90 is supplied with cooling air, which may be chilled, through the centre of a lockable shaft 91. The roller 90 includes a central tube 92 for example of aluminium, which is supported at each end by rotating bearings 93, and in the centre by a block 94. This arrangement provides an air space 95 adjacent the outer tube 96 of the roller 90 through which the air circulates before exhausting through the shaft 91 at the opposite end.

Referring to Figures 11, 12 and 13, the cooling rollers 90 are arranged in upper 101 and lower 102 pairs, which include a connecting piece or bogie 103 which holds the two rollers 90 in relative fixed position. The bogies 103 are pivotable about one end 104 by means of air cylinders 105 disposed at the other end. The arrangement provides for a trough 106 to be made in the path of the laminate 28, to oppose the natural tendency to curl.

An automatic feeding system described in more detail below, feeds a sheet or a set of aligned sheets of substrate material 75 to the laminator 1 by means of suction cups and a vacuum system (not shown) mounted on assemblies which are moved with air cylinders.

A flat feed table 110 is provided to support sheets 75, into which is set a pair of bars 111,112 having sensors 113, near to the nip rollers 20a,b (Figures 14,15). The top bar 111 can be pivoted upwards (as shown in Figure 13).

A set of pivotable rubber wheels 114, which are driven faster than the machine speed are mounted on an assembly below the feed table 110 in alignment with a set of free running upper wheels 115, to selectively drive the substrate to the machine.

The guillotine assembly 30, as shown in Figure 18, comprises a fixed main frame 35 supporting a slidable clamp frame 31 which has a sensor 33 mounted above the laminate path to sense the transverse gap between sheets of substrate material 75. A mobile blade carrier 32 is mounted on the clamp frame 31 and can be moved with respect to the clamp frame 31 by means of a rack 37 engaged by a drive wheel of a stepper motor 38 fixed to the clamp frame 31.

The blade carrier 32 supports a guillotine blade 34 extending transversely of the laminate 75, and a gap sensor position reader 39 connected to a number of gap sensors (not shown).

Slitter knives 116 are mounted on a bracket (see Figure 9) to make longitudinal cuts in the laminate 75 at the edges and between the substrate pieces 75. The knives 116 are mounted on a follower of a threaded shaft (not shown), and can be moved transversely by means of a stepper motor fitted with a series of sensors to detect the positions of the gaps.

The laminating machine 1 may be used for laminating film onto one side of a substrate, or onto both sides.

Substrate material 75 is fed automatically into the laminator l. A multi line feed system shown in Figure 19, includes four magazines 120a-120d of material which in this case is a pile of sheets 75, one for each of four lines.

The forward inner corners 121a-d of the four magazines 120a-d, which may be of various sizes, are placed in predetermined positions. The top sheet 75b,75c of each inner magazine 120b-120c is removed and brought forward, while the top sheet 75a-75d of each outer magazine 120a,120d is brought inwards by a variable amount which depends upon the width of the inner sheets 75b,75c. The four sheets 75a-75d may then be collected and fed to feed table 110 of the machine 1, where they may be each fed, side-by-side, into the machine in the manner described below.

Referring to Figures 14 and 15, when there is no material between the sensors 113, the upper bar 111 rotates upwards and the powered wheels 114 pivot upwards to drive a sheet 75 into the gap between the nip rollers 20a,b. The sheet 75 is then drawn into the machine flat across the feed table 110 by the driven nip rollers 20a,b. The next sheet 75' is dropped onto the first sheet 75 and is pulled along by the sheet 75 until it abuts the top bar 111 and is pulled into abutment with the bar 111 across its entire width.

When the end of the lower sheet 75 passes through the gap between the bars 111,112 it is detected by the sensors 113 and, by use of timers, the top bar 111 pivots upwards clear of the top sheet 75' and the powered wheels 114 lift into contact with the sheet 75', and grip it with the upper wheels 115. The lower wheels 114, which are rotating faster than the machine speed, drive the sheet 75' between the nip rollers 20a,b so that it catches up with the first sheet 75 and a predetermined small gap between the two sheets 75,75' is achieved. The top bar Ill and the lower wheels 114 return to their original positions for loading the next sheet.

The film 16 is loaded onto the frame 7 as shown in Figure 2, by manually placing the shafts 8a,9a of the magazine rolls 8,9 into the shaft holders 44,47. The chain drive 42 is operated to lift the upper roll 8 into its operative position, as dictated by limit switches. The frame 7 is then pushed to the laminator 1 where two guide pins 41 enter a bush on the main frame 2 of the laminator 1 to ensure correct positioning.

After passing over the tension rollers 10,11, which are adjusted for correct tension, the film passes between the radiant heaters 12 and the opposed reflector jacket 13, as shown in Figure 4, for example, such that the bonding face of the film faces the heaters 12. The reflector jacket 13 may be moved aside to load the film, and is then replaced in its working position (shown by solid lines).

The bonding face of the film 16 may thus be brought to melting temperature for correct bonding. Should the machine be stopped during operation, the heaters 12 may be pivoted about the tube 64 to move them away from the stationary film. Air, which may be chilled, may be passed through the tube 64 to assist cooling of the film, and also through a similar tube in the reflector jacket 13, into which residual heat may escape.

The heaters 72 within the nip rollers 20a,b, are used to bring them up to operational temperature at the beginning of a process, so that no heat is lost from the process into the nip rollers 20a,b. Two webs of heated film 16 pass between the nip rollers 20a,b on either side of the substrate 75 in a double-sided lamination process, with the bonding face of the film contacting the substrate 75. Variable bonding pressure is applied by the nip rollers 20a,b to form the laminate 28 which then passes between the wheels 27 which seal the longitudinal gaps between adjacent sheets 75 or lines of substrate.

To laminate a single face only of the substrate 75, the lower nip roller 20b is disconnected from the drive mechanism. Referring to Figure 6, the driven shaft 88 is disconnected from the drive shaft 81 by movement of the connecting gear 82 in a direction to the left in the Fig ure, by actuation of the cylinder 83. Actuation of the pressure unit 84 traps the braking disc 85 and restricts rotation of the lower nip roller shaft 86. Thus a frictional force is transmitted to the lower face of the substrate 75, which is not laminated, which tends to oppose the tendency of the single sided laminate to curl with the laminated side on the inside.

After initial bonding between the nip rollers 20a,b, further pressure is applied by the free running pressure rollers 22. Particularly during high speed lamination, it is important to carry out this repeat pressure in order to assist the bond over a greater time period.

Tension is created in the laminate 28 by the first set of driven pressure rollers 25,26. Part of the tension is transmitted to the nip rollers 20a,b, but, since the free running pressure rollers 22 are not powered, there is tension between the two sets 22,25 of pressure rollers which reduces the tendency to curl and allows the first set 23 of cooling rollers to reduce the surface temperature of the finished laminate 28. The cooling rollers 23,24 extract heat rapidly from the laminate 28 since they are in direct contact with it. The cooling air circulating through each roller 90, may be supplied from a chilled air system.

Also, to oppose the tendency to curl of the laminate 28, the cooling rollers 23,24 may be pivoted to create a trough. For example, Figure 11 shows a position of a set of rollers 90 in which actuation of the cylinder 105 pivots the right hand end of the upper bogie 103 in a downward direction. Thus the right hand roller of the upper pair 101 is pressed into the gap between the rollers of the lower pair 102. Alternatively, as shown in Figure 12, the left hand roller of the lower bogie may be pressed into the gap between the upper rollers. This action can also be used to oppose any natural tendency of the laminate 28 to curl due to tension problems.

During high speed operation it is unlikely that after passing between one set of driven pressure rollers and one set of cooling rollers the temperature will be sufficiently reduced to allow the slitter knife 116 to trim the finished laminate 28. Therefore a second set of cooling rollers 24 and a second set of driven pressure rollers 25 are provided. The pressure rollers 25 create tension and keep the laminate 28 flat, whilst allowing the cooling rollers 24 to be effective.

The laminate 28 may then pass to the guillotine assembly 30 for separating each sheet 75 longitudinally and transversely. When a gap between the trailing edge of one sheet and the leading edge of the next sheet passes the sensing device 33, a signal is generated which times the clamp frame 31 to grip the complete web of laminate 28.

The clamp frame 31 is then driven forward by the motor 38 at the same speed as the laminate 28.

A number of sensors then check the position of the gap in relation to the clamp frame 31. The amount by which the mobile blade carrier 32 must be moved is then calculated, and the stepper motor 38 drives the blade carrier 32 to the correct position above the gap. The guillotine blade 34 is actuated to cut the laminate 28, after which the clamp frame 31 releases the laminate 23b 28 and is driven back to its original position for the next operation.

Initially, the bracket carrying the slitter knives 116 is manually moved transversely into alignment with the longitudinal edges of each substrate sheet of the web of laminated material. As the web 28 moves past the sensors and slitter knife 116 any deviation in the position of the gap between substrate sheets is detected, and the stepper motor (which is not shown) is powered to rotate in either direction. This rotates the threaded shaft and the follower on which the knife 116 is mounted, so that the knife 116 moves either left or right to maintain its position in the centre of the gap.

Alternatively, for a single sided laminate where the transverse edges of the substrate sheets overlap slightly, the sheets may be separated by means of the single sided guillotine, shown in Figure 7.

The single sided guillotine mechanism includes a pair of feed rollers 125,126 at one end and a pair of discharge rollers 127,128 at the other end of the mechanism, one roller 126,127 of each pair being selectively drivable. A rotary knife 129 on one side of the laminate 28 path is pivotable about a central point 130 by means of a drive mechanism (not shown). An extendible knife 131 on the other side of the laminate path is linked to a movable cylinder 132 by a linkage 133 such that one stroke of the cylinder 132 causes the knife 131 to extend towards the rotary knife 129 and then retract again. A press 138 provided adjacent the extendible knife 131, which is actuable by means of a drive cylinder 139 to move towards the laminate path.A guide roller 134 is movable between an inoperative position away from the laminate path (indicated by broken lines) and an operative position in which it bends the laminate path so that a gap 135 forms under the overlapping portion 136 of a transverse edge of a substrate sheet. A sensor (not shown) is provided to detect the presence of the overlapping transverse edge 136 of the substrate sheet.

The laminate 28 is fed into the mechanism between the feed rollers 125,126 by means of the drive connected to, for example, the lower rollers 126, and around the driven discharge roller 127 with the other discharge roller 128 in an inoperative position (indicated by broken lines).

The laminate 28 follows a path indicated by broken lines with the guide roller 134 in the inoperative position, and the rotary knife in a position 129a substantially parallel to the laminate path. When the sensor detects an overlap, the inoperative discharge roller 128 is moved into an operative position (shown by solid lines), the guide roller 134 is moved towards the laminate path to bend the laminate 28 (indicated by solid lines), and the drive on the feed roller 125 is disconnected, the other feed roller 126 being braked to create slight tension in the laminate 28 and gently stretch it.

The rotary knife 129 is moved to a position 129b adjacent the guide roller 134 so that it enters the gap 135 between the overlapping edge 136 and the overlapped edge 137 of adjacent substrate sheets. A signal is produced at this point which reduces the speed of the discharge rollers 127,128, lifts the guide roller 134 clear of the laminate 28, and disconnects the drive of the rotary knife 129. As the laminate 28 is drawn towards the discharge rollers 127,128, the rotary knife 129 is carried around in the gap 135 to a position 129c opposite the extendible knife 131, where it is locked and the drive on the discharge roller 127 stops.

The cylinder 132 performs one stroke, such that the extendible knife 131 extends towards the rotary knife 129 by virtue of the linkage 133 and the two knives 129,131 cut the film 140 between the two edges of the substrate, then moves back clear of the laminate 28. The discharge roller 127 is once again driven to pass the cut leading sheet out of the mechanism.

The separation of the edges 136,137 of the sheets tends to produce a fold in the leading edge 136 of the trailing substrate sheet. The sheet is moved forward by a predetermined distance, and the rotary knife 129 reverses, for example by moving through 2000, to a position 129d in which it presents its flat end 141 towards the knife 129 and traps the edge 136 of the sheet between them so that the fold is flattened.

The free discharge roller 128 returns to an inoperative position (broken lines), and the rotary knife 129 returns to a position 129a substantially parallel to the laminate path, such that it forms a 'table' to guide the leading edge 136 of the laminate between the discharge rollers 127,128. The exact position of the rotary knife 129 is measured at this point so that the exact amount of rotation is known which is necessary for the drive, which may be a stepper motor, to put the rotary knife 129 into the critical position 129b adjacent the guide roller 134 when the next edge is sensed.

The process of operation described above may be altered so that material laminated on both sides, and encapsulate laminated material may also be cut. For example, the rotary knife may be fixed in the cutting position 129c, and the extendible knife 131 may be operated to cut the film in the gap between substrate sheets. For this purpose, the drive on the laminate may be disconnected at the appropriate time when a gap is sensed.

Claims (18)

CLAYS

1. A laminating machine for bonding film onto a substrate, having a radiant heater for heating a bonding layer of the film, movable between a position in which heat is directed towards a path followed by the film before bonding, and a position in which heat is directed away from the film path.

2. A laminating machine for bonding film onto a substrate, having rollers mounted on either side of a laminate path in staggered formation, a first roller, which is on one side of the laminate path, being movable towards a roller on the other side of the laminate path such that the laminate path is deviated from a straight line configuration between the rollers.

3. A laminating machine for bonding film onto a substrate, having a tension roller around which the film passes, and brake means actuable to restricting rotation of the tension roller.

4. A laminating machine for bonding film onto a substrate, having a pair of bonding rollers drivable by drive means, and means to disconnect one roller of the pair from the drive means, brake means being provided to restrict rotation of the one roller.

5. A laminating machine for bonding film onto a substrate, having an upper roll supporting frame and a lower roll supporting frame, which frames are movable with respect to one another.

6. A laminating machine for bonding film onto a substrate, having a feed table, sensing means mounted close to a bonding area of the machine which produces a signal when there is no substrate sheet adjacent the sensing means, and drive means actuable to drive a substrate sheet along the feed table towards the machine in response to the signal.

7. A laminating machine for bonding film onto a sub strate, having a wheel aligned with a longitudinal gap between sheets of substrate material in a laminate web, which wheel presses the film into the gap.

8. A guillotine assembly for use with the laminating machine to cut a web of laminate, the assembly comprising: a mobile clamp frame including means to clamp the web of laminate in response to a signal produced by means for sensing a gap between sheets of substrate material in the laminate; and a blade carrier mounted on the clamp frame and movable with respect to the clamp frame in response to a signal produced by sensing means for sensing the position of the gap; and means to operate a blade mounted on the blade carrier to cut the web.

9. A method of transversely cutting a moving web of material at a predetermined cutting position comprising the steps of: clamping the web to a clamp frame; moving the frame at the same speed as the web; sensing the cutting position; moving a blade carrier mounted on the clamp frame to the cutting position; and, operating a blade mounted on the blade carrier to cut the web.

10. A guillotine mechanism for use with a laminating machine to separate substrate sheets laminated on one side with film, the mechanism comprising: means for causing a gap to be formed between an overlapping transverse edge of a substrate sheet, and the overlapped edge of another sheet; first cutting means insertable into the gap; and second cutting means actuable to cooperate with the first cutting means to cut the film transversely between the substrate sheets.

11. A method of transversely separating substrate sheets of a single sided laminate produced by a laminating process, the method comprising the steps of: causing a gap to be formed between an overlapping transverse edge of a substrate sheet and an overlapped edge of another sheet; inserting first cutting means into the gap; and cutting the film between the sheets by means of second cutting means cooperating with the first cutting means.

12. A mobile frame for use with a laminating machine, and securable thereto, provided with shaft holders to support a magazine roll of film, the frame having means to lift the shaft holders to a position corresponding to an operational position of the roll.

13. A laminating machine for bonding film onto a substrate, comprising an upper roller supporting frame and a lower roller supporting frame, the frames being pivotable with respect to one another from a closed operational position to an open position to facilitate loading or removal of material, each frame supporting:: a tension roller around which a web of film is passed, having adjustable braking means actuable to alter the tension in the web of film; a radiant heater provided with a jacketed reflector, which is movable to direct radiant heat onto the film or away from the film; a pressure bonding roller which, in the operational position of the frames, forms a gap with the bonding roller supporting on the other portion such that bonding pressure is applied to the film and the substrate material when they pass through the gap; a free-running pressure roller which applies further pressure to the bonded laminate; a driven pressure roller which creates tension in the laminate; and a cooling roller which contacts the laminate to extract heat from it by conduction.

14. A method of bonding film onto a substrate, the film comprising a web of material provided on one face with a layer of bonding material, the method comprising the steps of: feeding the film web around a brakable tensioning roller and adjusting the braking to maintain a substantially constant tension in the film web; feeding the film web past a radiant heater such that the bonding material reaches a bonding temperature; feeding the film web and a substrate material between a pair of driven bonding rollers such that the bonding material contacts the substrate to form a laminate material; feeding the laminate between further driven pressure rollers to apply tension to the laminate, and to cooling rollers to remove heat from the laminate by conduction; moving the cooling rollers to deviate the path of the laminate when curling of the laminate occurs.

15. A laminating machine substantially as described herein, with reference to the accompanying drawings.

16. A method of producing a laminated material substantially as described herein, with reference to the accompanying drawings.

17. Apparatus for cutting a laminated material substantially as described herein, with reference to Figure 7 or Figure 18 of the accompanying drawings.

18. A method of cutting a laminated material substantially as described herein, with reference to Figure 7 or Figure 18 of the accompanying drawings.