WO2014088501A1

WO2014088501A1 - Flatbed applicator and a method for joining or laminating flat substrates

Info

Publication number: WO2014088501A1
Application number: PCT/SE2013/051443
Authority: WO
Inventors: Göran Johansson
Original assignee: Rollsroller Ab
Priority date: 2012-12-04
Filing date: 2013-12-04
Publication date: 2014-06-12
Also published as: SE1251370A1

Abstract

A flatbed applicator (1), for joining a first, thin, flat substrate and a second, flat substrate during a joining operation, comprising a table top (6), which exhibits a flat table surface (7) for supporting the substrates, two parallel, elongated guide and support means (13), and a traverse assembly (14), which is movable along the guide and support means and in the longitudinal direction (L) of the table top and which extends across the table top perpendicularly to said longitudinal direction (L) and comprises a squeezing means in the form of a squeeze roll (23), which extends across at least the major portion of the width (b) of the table top, said squeeze roll being vertically adjustable to enable it to be brought between a first, inactive position, where the squeeze roll clears and does not interact with the table top and/or said first and second substrates laid out on the table top, and a second, active position, where the squeeze roll interacts with the table top and/or said first and second substrates laid out on the table top, wherein the traverse assembly is adapted to be moved along the guide and support means during the joining operation with the squeezing means in the active position with said substrates between itself and the table top while the squeeze roll is caused to rotate about its axis and to exert a predetermined squeezing force upon the substrates. According to the invention, the flatbed applicator comprises heating means, which are adapted to bring the shell surface of the squeeze roll to a desired temperature or a desired temperature range during the joining operation, said desired temperature or desired temperature range exceeding the temperature of the air surrounding the squeeze roll.

Description

Flatbed applicator and a method for joining or laminating flat substrates

The present invention relates to a flatbed applicator, adapted for joining or laminating a first, flat substrate and a second, thin, flat substrate during a joining operation, comprising: - a table top, which exhibits a flat table surface for supporting the substrates;

- two parallel, elongated guide and support means; and

- a traverse assembly, which is movable along the guide and support means and in the longitudinal direction of the table top, and which extends across the table top perpendicularly to said longitudinal direction and comprises a squeezing means in the form of a squeeze roll, which extends across at least the major portion of the width of the table top, said squeeze roll being vertically adjustable to enable it to be brought between a first, inactive position, where the squeeze roll clears and does not interact with the table surface and/or said first and second substrates laid out on the table surface, and a second, active position, where the squeeze roll interacts with the table surface and/or said first and second substrates laid out on the table surface.

The invention also relates to a method for joining or laminating a first, flat substrate and a second, thin, flat substrate. A flat applicator of the above-mentioned type is usually called a flatbed applicator or flatbed laminator. One example of a flatbed applicator is the device which is marketed under the trademark ROLLSROLLER^® and described in US 6,102,096, whereas lamination by means of the flatbed applicator is described in US 6,406,582. The present invention also relates to a method for joining or laminating two substrates by means of a flatbed applicator.

In particular, the present invention relates to a flatbed applicator and a method for applying a self-adhesive fabric/foil to a support, e.g. for manufacturing flexible face signs or traffic signs. In the present context, "fabric" does not have to be woven. One problem here is that the adhesive substance on the fabric/foil either has not been applied with a uniform thickness on the substrate thereof or cannot be caused to spread out into an even layer during the joining operation on the flatbed applicator. When the self-adhesive fabric/foil is transparent, an uneven layer of adhesive substance will therefore be visible in the product manufactured in the flatbed applicator. As a rule, the layer of adhesive substance is more uneven and/or of a lower quality on a more inexpensive self-adhesive fabric/foil than on a more expensive one. Furthermore, the adhesive substance may contain micro-droplets of water, and when the product manufactured in the flatbed applicator is subjected to heating, e.g. by radiation from the sun, the water in the micro-droplets may evaporate and form vapour blisters, which causes the foil to come loose from the substrate. Furthermore, a milky white discolouration, resulting from the squeezing pressure being unable to squeeze out micro-bubbles of air from the adhesive substance, may appear.

The object of the present invention is to produce a flatbed applicator of the above- mentioned type and a method enabling a quicker and more reliable joining of two flat substrates.

The flatbed applicator according to the invention is characterized in that it comprises heating means, which are adapted to bring the shell surface of the squeeze roll to a desired temperature or a desired temperature range during the joining operation, said desired temperature or desired temperature range exceeding the temperature of the air surrounding the squeeze roll.

Since the squeeze roll is heatable, a joining temperature can be selected at which a more inexpensive and/or an unevenly applied adhesive substance is heated and spreads out into an even film by the pressure and heat from the heated squeeze roll, and at which the micro- droplets and any micro-bubbles can move through the heated adhesive substance to a side edge of the self-adhesive fabric/foil.

In the production of graphic signs, i.e. production of e.g. tension fabric displays and decoration, the heating means are suitably adapted to bring the shell surface of the squeeze roll to a desired temperature or a desired temperature range between 25 °C and 250 °C.

The lower temperatures are sufficient for manufacturing flexible face signs or traffic signs, whereas real textile printing requires higher temperatures. In the present context, textile refers to materials and products made of natural and/or synthetic fibres by textile technology.

The heating means can be disposed radially outside the squeeze roll and can then comprise e.g. IR radiators. In a preferred embodiment, however, they are instead disposed inside the squeeze roll, and are then suitably disposed at a radial distance from the axis of rotation of the squeeze roll that is at least 0.8 times the radius of the squeeze roll, preferably at least 0.9 times the radius of the squeeze roll. Since the squeezing by means of the squeeze roll is performed intermittently in the flatbed applicator, it is important that all surface areas on the shell surface are within the predetermined temperature range when initiating the application operation in the flatbed applicator, and it is therefore important that the temperature control can be executed rapidly. Furthermore, the location of the heating means close to the shell surface enables them to be turned off except at the instant when the squeeze roll is used, and to thereby save energy, on the one hand, and to prevent the top side of the squeeze roll from becoming hotter than the bottom side, on the other hand.

To offer a possibility of a rapid control of the heating power, the heating means disposed inside the squeeze roll advantageously comprise one or several heating wires for electrical heating. In a first embodiment, said one or several heating wires run in straight grooves, which are parallel to the axis of rotation of the squeeze roll and extend from a first end to a second end of the squeeze roll. In a second embodiment, said one or several heating wires instead run in helical grooves about the axis of rotation of the squeeze roll. In both cases, it is suitable that the grooves have a V-shaped cross-section. Such a cross-section enables the heating wires to increase their length when during heating, and to decrease it during cooling, without this having any influence on the shape of the shell surface of the squeeze roll. In the above-mentioned first embodiment, the further advantage is gained that a possibility of an enhanced temperature control of the shell surface when the roll is heated, but in a resting position, is obtained. When using helical grooves, it is suitable that the heating wire comprises a first conductor portion, which runs in a first helical groove from the first end to the second end of the squeeze roll, and a second conductor portion, which is disposed in series with the first conductor portion and which runs in a second helical groove from the second end of the squeeze roll and back to the first end thereof, said second helical groove being parallel to the first helical groove. Thereby, the magnetic field produced around the helical, second conductor portion neutralizes the field produced by the first helical conductor portion when current flows through the conductor portions.

Irrespectively of whether the heating of the shell surface of the squeeze roll takes place from the outside or from the inside, it is suitable that the flatbed applicator comprises a control device, which comprises a control unit for supplying and controlling the energy to said heating means in order to maintain the temperature of the shell surface at said desired temperature or within said desired temperature range. When the heating device is located inside the squeeze roll, it is suitable that the squeeze roll comprises an overheating protector, which is adapted to interrupt the current through said one or several heating wires when the temperature in the squeeze roll exceeds a predetermined temperature. Furthermore, it is suitable that the control device comprises one or several temperature transmitters for direct or indirect measurement of the temperature of the shell surface, wherein said one or several temperature transmitters can comprise one or several sensors for detecting thermal radiation from the shell surface of the squeeze roll, said one or several sensors being disposed such that they have an unobstructed field of view to the shell surface. Said one or several sensors is/are adapted to transmit actual temperature values of the temperature of the shell surface to said control unit, wherein the control unit is adapted to control the energy supplied to the heating means so that the temperature of the shell surface is maintained at said desired temperature or within said desired temperature range.

When the heating means are disposed inside the squeeze roll, it is suitable that it comprises a circularly cylindrical tubular member, axle journals which are disposed at the ends of the tubular member, a first layer of an elastic material surrounding the tubular member, a second layer of an elastic material surrounding the first layer, and a third layer of an elastic material surrounding the second layer, said third layer forming the shell of the squeeze roll and having a hardness that is less than the hardness of the first layer and the second layer, wherein said one or several heating wires are disposed in recesses in the first layer and are covered by the second layer. In a squeeze roll with external heating, the two inner layers can be combined into a single layer.

Preferably, said first layer and said second layer consist of EPDM rubber, which has a hardness in the range of 70-80 °degrees Shore, whereas said third layer consists of an EPDM rubber with textile fibres mixed into it, said third layer having a hardness in the range of 35-55 degrees Shore. EPDM rubber is heat resistant and can also be replaced by silicone rubber. The layers are suitably joined together with each other by vulcanizing, but it is also possible to use a glue for joining them together.

The method according to the invention is characterized by the steps specified in claim 18.

In the following, the invention will be described more closely with reference to

accompanying drawings.

Figure 1 is a perspective view which shows an embodiment of a flatbed applicator according to the invention. Figure 2 is a perspective view which shows guide and support means, and a traversing carriage of the flatbed applicator of Figure 1.

Figure 3 is a perspective view which shows a guide being part of the guide and support means of Figure 2.

Figure 4 is a perspective view which shows a traverse assembly being part of the flatbed applicator of Figure 1. Figure 5 is a perspective view which shows a traversing carriage being part of the traverse assembly of Figure 4 and which is also shown in Figure 2.

Figure 6 is a schematically simplified cross-sectional view of the roll of Figure 7. Figure 7 is a side view of a squeeze roll in the flatbed applicator of Figure 1.

Figure 8 is a longitudinal sectional view of the roll of Figure 7, along the section indicated by VIII-VIII in Figure 7. Figure 9 is a schematically simplified cross-sectional view of a roll that is an alternative to the roll of Figures 6-8.

Figure 10 is a schematic perspective view of the roll of Figure 9, with the outermost rubber layer removed for the purpose of showing the longitudinal grooves for the heating wires.

Figure 11 is a simplified scheme for the control of the temperature of the shell surface of the squeeze roll.

Figure 12 is a front view of a portion of the traverse assembly and shows means for setting the desired temperature of the shell surface of the squeeze roll and means for measuring actual temperature thereof.

Figure 13 is a side view of an upper portion of the traverse assembly of Figure 4, and which in addition to the squeeze roll shows means for lifting and lowering thereof.

Figure 14 is a perspective view of the same upper portion of the traverse assembly and shows means for controlling the heating of the squeeze roll. Figures 15-24 show different steps when laminating a self-adhesive foil to a substrate by means of a flatbed applicator according to the invention. Figure 1 shows one embodiment of a flatbed applicator 1 according to the invention, wherein said flatbed applicator, in the shown embodiment, is used for joining or laminating a first substrate, in the form of a thin, flexible and self-adhesive fabric/foil, and a second substrate, in the form of a thin substrate. The substrate can e.g. be a thin, flexible fabric, e.g. a polymer fabric. The substrate can alternatively be a rigid sheet, such as e.g. a sheet of metal, a sheet of glass or a sheet of hard plastic.

It is appreciated, however, that the flatbed applicator according to the invention can be used for other joining or laminating applications. The flatbed applicator 1 comprises a support frame 2, which in the shown embodiment comprises a framework with stays and struts forming a leg frame 3, which, if needed, can be equipped with lockable wheels 4 at the bottom for movement of the flatbed applicator 1. In the shown embodiment, the support frame 2 also comprises channel-shaped shelves 5, forming storage compartments for e.g. tools and substrate materials. The support frame 2 is preferably of metal.

Furthermore, the flatbed applicator 1 comprises a substantially rectangular table top 6, which is supported by the support frame 2 and exhibits a substantially horizontal and flat table surface 7, which is delimited by two parallel long sides 8 and two parallel short sides 9 of the table top 6. The table top 6 is fixedly connected to the support frame 2, so that the support frame 2 and the table top 6 form a stable and non-resilient structure. The table top 6 most preferably comprises a horizontal frame or framework of steel girders 10, a glass sheet 11 which rests on the frame 10, and a comparatively soft fabric or cutting mat 12 which rests on the glass sheet 11.

In its transverse direction T, the table top 6 has a predetermined width, which is preferably in the range of 100-250 cm, and, in its longitudinal direction L, a predetermined length, which is preferably in the range of 200-1000 cm. Furthermore, the flatbed applicator 1 comprises guide and support means in the form of two horizontal and parallel guides 13 (see Figures 2 and 3), which extend in the

longitudinal direction L of the table top 6 at each long side 8, below the plane of the table top 6, and a traverse assembly 14 (see Figures 1 and 4), which is adapted to travel along the guides 13 carried by travelling means 19, which are best shown in Figure 5.

The guides 13 are fixedly connected to the table top 6 via vertical struts 15, which are attached to the bottom side of the table top 6, so that the guides 13 extend in parallel with, and slightly below and inside, the long sides 8 of the table top 6. At the short sides 9 of the table top 6, the guides 13 preferably extend all the way to the edge of the table top 6. In the shown embodiment, each guide 13 consists of an elongated pipe, which has been reshaped by rolling into a substantially T-shaped cross-section, wherein the resulting top portion 16 of the T is fixedly connected to the vertical struts 15, and wherein the resulting vertical post of the T is a box girder 17, which has a rectangular cross-section, so that one long side of the girder 17 is facing outward. The resulting pipe being T-shaped in cross-section preferably consists of metal. The traverse assembly 14 comprises travelling means in the form of two carriages 19, which are adapted to travel along a respective one of the guides 13. For this purpose, each carriage 19 comprises suitable slide or roller bearings, which are adapted to interact with corresponding sliding or travelling tracks on the top, bottom and outer side of the guide 13. The carriages 19 have a predetermined extension in the longitudinal direction of the guides 13, whereby it is ensured that the carriages 19 are mutually parallel. In the embodiment shown in Figure 5, each carriage 19 has six wheels, three at each end, for bearing abutment against the top, bottom and outer side of the guide 13. Furthermore, the traverse assembly 14 comprises two substantially vertical posts 20, which at their lower end are fixedly connected to a respective one of the carriages 19 via a substantially horizontal strut 21. The posts 20 extend upwardly above the plane of the table surface 7 outside the respective long side 8 of the table top 6. In the embodiment shown in Figure 4, also the posts 20 are provided with a respective holder 20' for a respective end of a roll of web material, not being shown but extending in parallel with the traverse assembly. The traverse assembly 14 also comprises and elongated, rigid and substantially horizontal beam 22 (see Figures 1 and 4), which is fixedly connected to the upper ends of the posts 20. If desired, the beam

22 can of course also be disposed on the bottom side of the table top 6.

Accordingly, the guides 13 constitute guide and support means for the traverse assembly 14, wherein the carriages 19 with their slide or roller bearings constitute the travelling means of the traverse device 14, which comprise guiding and bearing means interacting with the guide and support means to enable a linear movement of the traverse assembly 14 in the longitudinal direction L of the table top 6 while maintaining good stability of the traverse assembly 14 in a vertical direction as well as in the movement direction of the traverse assembly 14. Accordingly, the traverse assembly 14 extends in the transverse direction T of the table top 6, but is adapted to move in the longitudinal direction L of the table top 6.

Inside of each post 20 and above the respective long side 8 of the table top 6, the traverse assembly 14 comprises a vertically aligned mounting member 23 which, when the beam 22 is disposed above the table top 6, is connected at its upper end to the beam 22 and extends vertically downward therefrom. At its lower end, each mounting member 23 comprises an axle seat 24' in the form of a bearing housing (see Figure 11), in which mounting member a squeezing means in the form of a substantially horizontal roll 24 is rotatably mounted. Accordingly, the mounting members 23 with the axle seats 24' constitute mounting means for the roll 24, which extends substantially across the entire width b of the table top 6. In other words, one end 25 of the roll 24 (see Figure 8) is disposed at one long side of the table surface 7, and the other end 26 (see Figure 8) is disposed at the other long side of the table surface 7.

The mounting members 23 also comprise actuators for vertical movement of the roll 24 between an upper, non-operative or inactive position, where the roll 24 does not interact with the table surface 7, and a lower, operative or active position, which constitutes a squeezing position of the roll 24, where the shell surface 27 of the roll 24 interacts with the table surface 7 or with substrates laid out on the table surface 7. Such an actuator preferably comprises at least one pneumatic cylinder disposed in each mounting member 23 for simultaneous, vertical movement of the axle seats, but alternatively other actuators, such as hydraulic, electric or mechanic actuators, can be used. The pneumatic cylinder has piston rod, protected by a surrounding bellows 16, and, for operating the pneumatic cylinders to raise and lower the roll, on top of the traverse assembly 14 at each side of the flatbed applicator 1 , there is an operating lever for controlling the pressurized air, suitably in the form of a joystick 50, see Figures 1 and 12. On the side of the beam 22, close to the ends thereof, there is an emergency stop button 51 , a manometer 52 for measuring the pressure of the pressurized air, and a regulator 53 for setting the desired pressure.

According to an alternative, not shown embodiment of the traverse assembly, the roll 24 is movably mounted to the posts 20, so that the roll 24 can be moved up and down along these between said upper and lower positions by means of actuators for vertical movement of the roll 24, said actuators being arranged inside the posts 20. In this embodiment, the beam 22 can be omitted, wherein the roll 24 is the only part of the traverse assembly which extends across the table surface 7.

Preferably, the roll 24 is releasably mounted to the traverse assembly 14, so that it easily can be replaced, e.g. by rolls having other dimensions or characteristics, e.g. other surface characteristics.

The roll 24 suitably comprises a circularly cylindrical tubular member 28, which extends in the axial direction of the roll and forms the core of the roll 24 (see Figures 6, 7 and 8). The tubular member 28 is preferably of metal, and preferably has an outer diameter in the range of 70-110 mm and a material thickness in the range of 2-20 mm. Axle journals 29 are disposed at the ends of the tubular member 28. Also the axle journals 29 are preferably of metal, and they are preferably connected to the inner delimiting surface of the tubular member 28, as is shown in Figure 8.

The roll 24 further comprises a first layer 30, surrounding the tubular member 28, of a heat resistant, elastic material, e.g. EPDM or silicone rubber. The layer 30 has a radial thickness which is preferably in the range of 4-20 mm. The layer 30 can be glued and/or shrink fitted to the tubular member 28, or be fixedly disposed to the tubular member 28 in another way known in the art, so that the layer 30 does not slip on the tubular member 28. Preferably, the layer 30 is comparatively hard, and has suitably a hardness in the range of 70- 80 degrees Shore.

The roll 24 further comprises a second layer 31 of an elastic material, said second layer 31 surrounding the first layer 30. The layer 31 is rotationally symmetrical and has a radial thickness which is preferably in the range of 1-5 mm. Preferably, the second layer 31 is of the same material as the first layer 30.

The roll 24 further comprises a rotationally symmetrical, third layer 32 of a heat resistant, elastic material, said third layer 32 surrounding the second layer 31. The layer 32 forms the shell of the roll 24 and serves the purpose of interacting with the table surface 7 and substrates laid out on the table surface 7, when the roll 24 is at its lower position. The layer 32 has a radial thickness which is preferably in the range of 2-10 mm. Preferably, the third layer 32 is a fibre-reinforced polymer, e.g. an EPDM rubber with textile fibres mixed into it, which has proved to have characteristics which prevent substrates being processed from sticking to the roll. Preferably, the layer 32 has a hardness that is less than the hardness of the underlying layers 30 and 31, e.g. a hardness in the range of 35-55 degrees Shore. The different elastic layers 30, 31 and 32 may be shrink fitted and/or glued to each other, or fixedly disposed to each other in other ways known in the art, so that the layers 30, 31 and 32 do not slip relative to each other, but they are preferably vulcanized to each other.

In the embodiment shown in Figures 6-8, the roll 24 further comprises an electrical conductor 33, which follows a helical path around the first layer 30. The conductor 33 can be in the form of a metal wire with a circular cross-section, but can alternatively be in the form of a flat belt. In case the conductor 30 is in the form of a metal wire with a circular cross-section, the wire preferably exhibits a diameter in the range of 0.5-4 mm, or more preferably of 2-3 mm.

Preferably, the electrical conductor 33 is disposed in a recess 34 in the first layer 20, so that it is recessed therein. The recess 24 is suitably constituted of grooves 34. According to a preferred path, the conductor 33 runs from the first end 25 of the roll 24 in a first helical groove 35, to the second end 26 of the roll, where the path of the conductor 33 turns and runs in a second helical groove 36 back to the first end 25, said second helical groove 36 running in parallel with the first helical groove 35. Accordingly, the conductor 33 comprises a first, helically wound conductor portion 37, which runs from the first end 25 of the roll 24 to the second end 26 thereof, and a second helically wound conductor portion 38, which is disposed in series with the first conductor portion 37 and runs from the second end 26 of the roll 24 and back to the first end 25 thereof. By arranging the conductor 33 in this way, the advantage is obtained that the magnetic field produced by a current flowing through the first conductor portion 37 is substantially completely neutralized by the magnetic field produced by the current flowing through the second conductor portion 38. Preferably, both conductor portions exhibit a pitch in the range of 10-15 mm/revolution.

At the second end 26 of the roll 24, where the path of the conductor 33 turns, the roll 24 exhibits an overheating protector 39, which is disposed between, and in series with the conductor portions 37 and 38. The overheating protector 39, which is placed in a recess 40 of its own in the layer 30, is adapted to interrupt the current when the temperature in the roll 24 exceeds a predetermined temperature, at which temperature the roll 24, the table surface 7, or substrates laid out on the table run the risk of being damaged, which temperature, for example, can be in the range of 110-130 °C, but also up to approx.

250 °C, depending on the materials selected for the components in question. At the first end 25 of the roll 24, the conductor portions 37, 38 are connected to a respective slip ring (not shown), which are integrated into a swivel coupling 41 (see Figure 1 1) disposed on the axle journal 29 to form a power transmission means between the rotating roll and the mounting member 23, in a known way.

When manufacturing the roll 24 in the embodiment shown in Figures 6-8, the axle journals 29 are attached to the tubular member 28, for example by means of soldering or welding, whereafter the first layer 30 is attached to the outside of the tubular member 28, for example by means of gluing and/or shrink fitting. Thereafter, the recesses 34 and 40 are milled into the shell surface of the layer 30. Preferably, the recess 34 is milled such that it obtains a V-shaped cross-section. Thereafter, the conductor portions 37, 38 and the overheating protector 39 are connected to each other and are placed in their respective recesses 34 and 40. Thereafter, the second layer 31 is placed on top of the first layer 30. The second layer 31 serves the purpose of covering and protecting the conductor 33 and the overheating protector 39. The second layer 31 also serves the purpose of preventing the conductor 33 from penetrating outwardly in the roll and deforming the substrate-contacting layer 32, e.g. when the conductor 33 expands during heating. If the conductor 33 is allowed to deform the layer 32, irregularities may be formed in the shell surface 27 of the roll 24, which irregularities in their turn may influence and, in the worst case, deform and leave tracks in the substrates which the flatbed applicator 1 is to join together, but by giving the recesses 34 a V-shaped cross-section, it becomes easier to avoid irregularities in the shell surface 27 of the roll 24. Since there is an expansion space for the conductor 33 above the bottom position of the recess 34, the small thermal expansion 33 which the conductor is subjected to in one turn can be accepted, and the thermal expansions of all turns of the conductor 33 will not be accumulated at one end of the conductor 33. Finally, the third layer 32 is placed on top of the second layer 31, whereafter the layers 30-32 are joined together by vulcanizing. Alternatively, the layers 30-32 can be joined together in other ways as the roll 24 is built up, for example by gluing and/or shrink fitting. In an alternative embodiment of the roll 24, shown in Figures 9 and 10, a plurality of heating wires 33' are placed in recesses 34 in the form of straight grooves 35', which are parallel to the axis of rotation of the roll 24 and extend from a first end 25 to a second end 26 of the roll 24. As in the foregoing, the grooves preferably have a V-shaped cross- section, and the heating wires 33' can be connected to each other such that every other heating wire 33' in the circumferential direction of the roll 24 conducts current from the first end 25 of the roll 24 to the second end 26 thereof, whereas the other heating wires 33' conduct the current in the opposite direction. Thereby, slip rings are disposed at the same end of the roll 24. However, it is also conceivable that the slip rings are disposed at a respective end of the roll 24, and that all heating wires 33' conduct current in one and the same direction from one roll end to the other. This embodiment of the roll 24 offers a possibility to arrange the current supply to the heating wires 33' in such a way that only a sector of the periphery of the roll shell 27 is heated. This is an advantage during the short interruptions of the roll displacement which occur during the application of a self-adhesive fabric/foil to a substrate while applying the method described below. When the roll is temporarily halted, a heating of the whole roll shell would cause the heat to rise upward and the top side of the roll would become much hotter than the bottom side.

In another conceivable, but not shown embodiment, the roll 24 is adapted to be heated externally instead of internally. Such external heating can be accomplished with conventional IR radiators which are directed toward the shell surface 27 of the roll 24. They are then preferably mounted on the traverse assembly 14.

As is shown in Figure 11 , the flatbed applicator comprises a control device 43 for supplying and controlling current to the heating means, irrespective of whether these are disposed inside the roll 27 or in external IR radiators for heating the shell surface 27 of the roll 24. Thereby, the control device comprises a voltage source 44 and a control unit 45, which preferably comprises controls for regulating the current through the conductor 33, e.g. in the form of a keypad for setting the desired temperature or desired temperature range of the shell surface of the roll. Some parts of the control device can be mounted to the support frame 2 below the table top 6, but preferably at least some parts of the control unit 45 are mounted to the traverse assembly 14, suitably to the beam 22, as is shown in Figures 11 and 12, where an operator can easily reach the controls thereof.

Electrical wires, connected to the electrical conductor 33 via the above-mentioned slip rings in a swivel coupling 41, run from the control device. Thereby, the slip rings are adapted to ensure the electrical contact between the conductor 33 and the voltage source 44 of the control device when the roll 24 is rotating.

Preferably, the voltage source is adapted to supply low voltage to the conductor 33. As used herein, low voltage refers to a voltage up to 72 V. Accordingly, the voltage source can comprise a battery, or a transformer for stepping the nominal armature voltage down in a known way, but preferably the voltage source 44 delivers normal household voltage and the transformer is disposed in connection to the control unit 45. Accordingly, the conductor 33 functions as a heating wire, by means of which the roll 24 is heatable, so that the shell surface 27 thereof can be brought to a desired temperature or a desired temperature range, wherein the control unit 45 of the control device is adapted to ensure that a suitable current value, e.g. 10 A at 72 V, is fed through the conductor 33, so that the desired temperature or temperature range of the shell surface 27 is reached and maintained, at least when the roll 24 is moved across the table surface 7 in its lower, operative or active position. For this purpose, the control device preferably comprises one or several temperature transmitters 46 for direct or indirect measurement of the

temperature of the shell surface 27. As used herein, direct measurement means that the temperature of the shell surface 27 is measured with a temperature transmitter, which measures the temperature of the shell surface 27 directly. As used herein, indirect measurement means that the temperature of the shell surface 27 is estimated by means of 1 temperature transmitter which measures the temperature inside the roll 24, by means of which measurement value the temperature of the shell surface 27 then can be estimated or calculated. Examples of temperature transmitters 46 for direct measurement are

thermocouples placed on the shell surface or, which is preferred and will be described closer in the following, an IR sensor 46 (see Figures 11 and 12) directed toward the shell surface 27 for remote measurement of the temperature of the shell surface. One example of a temperature transmitter for indirect measurement of the temperature of the shell surface is a thermocouple placed inside the roll.

Preferably, said temperature transmitter(s) 46 comprise(s) one or several sensors for remote measurement of the temperature of the shell surface 27. Preferably, this or these transmitters comprise(s) one or several sensors 46 for detecting thermal radiation, i.e. radiation in the IR range, said one or several sensors being arranged such that they have an unobstructed field of view to the shell surface 27 of the roll 24. The sensor or sensors 46 can e.g. be disposed at the bottom side of the beam 22 so that they have an unobstructed field of view to the shell surface 27 of the roll 24. Thereby, the sensor or sensors 46 is/are adapted to transmit actual temperature values of the temperature of the shell surface 27 to the control unit 45 of the control device 43, wherein the control unit regulates the current through the conductor 33 so that the temperature of the shell surface is maintained at the desired temperature or within the desired temperature range. Preferably, this regulation is a pulse regulation, wherein the control device 43 switches the current through the conductor 33 off and on so that the desired temperature or desired temperature range is obtained. The current to the control device 43 and further through the control unit 45 to the conductor 33 passes through a current switch 47 and a power selector switch 48, see Figure 14, which both are located between the current source 44 and the control unit 45. The power selector switch 48 controls the power of the current pulse passing to the conductor 33. When the current supply is switched on, a warning light 49, shown in Figure 12 and disposed in the centre of the top side of the beam 22, is illuminated. It is appreciated that the desired temperature or temperature range of the shell surface 27 can vary depending on the type of substrates which are to be joined or laminated and/or depending on the type of adhesive or self-adhesive layers which are used during the joining operation. Accordingly, the control device preferably allows setting of the desired temperature or temperature range before a joining or laminating operation. Trials have shown that the desired temperature, for most substrates and adhesives, is usually in the range of 25-80 °C, and more preferably of 30-60 °C, for fabric/foil or sheet material, but during textile printing up to 250 °C, usually within the range of 60-230 °C. The fabric materials usually have a reinforcement consisting of a polyester core, which is baked into a white pigmented PVC emulsion, and the PVC layer has a top coating of acrylic, which prevents the softener from reacting with the adhesive substance. When foil is applied to fabric or sheet material, the temperature is, as a rule, in the range of 25-60 °C. When processing of textile materials is concerned, the temperature range is 60-230 °C, depending on the type of textile in question, and the ink which is to be heat set into it. The flatbed applicator 1 according to the invention can be used in different ways. In the following, one method will be described more closely with reference to Figures 15-24, where a flexible, self-adhesive fabric/foil 61 is applied onto and attached to a substrate 60. The substrate 60 can e.g. be a rigid sheet, for example of polycarbonate, acrylic, PVC or another plastic, or a second flexible fabric, for example a fabric of textile material.

The self-adhesive fabric/foil 61 exhibits a first layer, which has a front side usually exhibiting some kind of decoration or message. An adhesive, second layer, which in the initial state is covered by a protective film 64, is disposed on the back side of the first layer. In some cases, however, it is desirable to apply only an adhesive layer to a substrate, and thus dispense with decoration or message. This is e.g. the case, if it is desired to manufacture e.g. self-adhesive, flat profiles for use when locking the edges of the fabric/foil in a tension fabric display to the frame on which the fabric/foil is fixed, see e.g. US 5,893,227. In such a case, the self-adhesive fabric/foil is applied e.g. to a 1 mm thick sheet of polycarbonate, or a 3 mm thick sheet of polyacrylate or polycarbonate. These sheets are then cut into profiles of approx. 12 mm width. Before starting an application operation, an operator sets a desired temperature or desired temperature range of the shell surface of the roll by means of a keypad of the control unit 45 of the control device 43 and switches on the current supply to the conductors 33 of the roll 24. Thereby, the control device ensures that the shell surface 27 of the roll 24 is heated to the desired temperature or the desired temperature range. Thereafter, the operator clears the table surface 7 by moving the traverse assembly 14 to one short side of the table top 6. Thereafter, the operator places the substrate 60 on the table surface 7, as is shown in Figure 15. Thereafter, the operator places the self-adhesive fabric/foil 61 on top of the substrate 60, so that the self-adhesive layer, still with the protective film 64 in place, is facing the substrate 60, as is shown in Figurel6, whereafter the operator positions the fabric/foil 61 in a desired position on the substrate 60.

Thereafter, the operator moves the traverse assembly 14, with the roll 24 in its upper position, to a position above the fabric/foil 61 where a first portion 62 of the fabric/foil protrudes on one side on the roll 24, and where a second portion 63 protrudes on the other side of the roll 24, as is shown in Figure 17. Preferably, the traverse assembly 14 is placed substantially straight above the fabric/foil 61 in this step, so that said portions 62, 63 of the fabric/foil are substantially equal in length. Thereafter, the operator brings the roll 24 to its lower position, so that the fabric/foil 61 and the substrate 60 are clamped between the roll 24 and the table surface 7 with said portions 62, 63 of the fabric/foil protruding one each side of the roll 24.

Thereafter, the operator passes the first portion 62 of the fabric/foil over the roll 23, as is shown in Figure 18, so that the first portion 62 is brought to rest upon the second portion 63 of the fabric/foil with the protective film 64 exposed, and so that a first portion 65 of the substrate 60 is exposed. Thereafter, the operator removes the protective film 64 from the first portion 62 of the fabric/foil, so that the self-adhesive layer of the portion 62 is exposed, as is shown in Figure 19, whereafter the operator cuts off the protective film 64 approx. 10 cm from the roll 24, as is shown in Figure 20. Preferably, the operator folds the remaining edge of protective film double, and forces it in under the roll 24, as is shown in Figure 21, which facilitates the removal of the remaining protective film 64, which is done at a later stage, as described in the following.

Thereafter, the operator moves the traverse assembly 14, still with the roll 24 in the lower position, across the first substrate portion 65, i.e. across the exposed portion of the substrate 60, as is shown in Figure 22, wherein the heated roll 24 rolls across the substrate portion 65, brings the first portion 62 of the fabric/foil back to its intended position over the substrate 60 and squeezes the exposed, self-adhesive layer of the first portion 62 of the fabric/foil 61 against the substrate 60 in a controlled manner, so that the first portion 62 of the fabric/foil and the corresponding portion of the substrate 60 are joined together with each other under the influence of the pressure and heat from the heated roll 24.

Thereafter, the operator brings the roll 24 to its upper position, and moves the traverse assembly 14 back to a position which is directly in front of the previously cut edge of the protective film 64, whereafter the operator brings the roll 24 to its lower position, so that the fabric 61 and the substrate 60 are once again clamped between the roll 24 and the table surface 7.

Thereafter, the operator passes the second fabric portion 63 over the roll 24, as is shown in Figure 23, so that the second portion 63 of the fabric/foil is brought to rest upon the first portion 62 of the fabric/foil with the protective film 64 exposed and so that a second portion 66 of the substrate 60 is exposed. Thereafter, the operator removes the remaining protective film 64 from the portion 63 of the fabric/foil, preferably by grabbing the above- described, double-folded edge of protective film.

Thereafter, the operator moves the traverse assembly 14 across the second substrate portion 66 in the same way as with the first substrate portion 65, wherein the heated roll 24 brings the second portion 63 of the fabric/foil back to its intended position over the substrate 60 and squeezes the exposed, self-adhesive layer of the second portion 63 of the fabric/foil against the substrate portion 66 in a controlled manner, so that the second portion 63 of the fabric/foil and the substrate portion 66 are joined to each other under the influence of the pressure and heat from the heated roll 24.

Finally, the operator brings the roll 24 to its upper position and moves the traverse assembly 14 to one short side of the table top 6, as is shown in Figure 24, so that the finished laminate can be removed from the table surface 7.

It is appreciated that the flatbed applicator alternatively can be used without heating the roll, in which case the operator simply switches off the current supply to the conductor 33 or sets a desired temperature corresponding to the room temperature in the room where the flatbed applicator is located. Accordingly, the flatbed applicator according to the invention allows laminating or joining of substrates in a first operating mode, where the roll is unheated, and a second operating mode, where the roll is heated. To avoid long waiting times between these operating modes, i.e. for heating and cooling, respectively, of the roll, it is advantageous that the roll is designed such that only the outer portion of the roll 24 is heated in the second, heated operating mode. Trials have shown that the means for heating the shell surface of the roll, i.e. the conductor 33 in the above- described embodiment, preferably should be disposed close to the shell surface of the roll. Preferably, the means for heating the shell surface should be disposed at a radial distance from the axis of rotation of the roll that is greater than or equal to 0.8 times the radius of the roll, and most preferably greater than or equal to 0.9 times the radius of the roll. This arrangement implies that only the outer portion of roll has to be heated and kept heated in the second, heated operating mode, which on the one hand ensures that the desired temperature of the shell surface of the roll is reached quickly when the heating of the shell surface is initiated, and on the other hand that a rapid cooling of the roll is obtained when the heating is interrupted.

In the foregoing, the invention has been described based on a specific embodiment. It is appreciated, however, that other embodiments are encompassed within the scope of the invention. For example, it is appreciated that the heating of the roll can be accomplished in other ways than by the above-described heating wire, e.g. by induction-based heating.

Claims

C L A I M S

1. A flatbed applicator (1), adapted for joining or laminating a first, flat substrate (60) and a second, thin, flat substrate (61) during a joining operation, comprising:

- a table top (6), which exhibits a flat table surface (7) for supporting the substrates (60, 61);

- two parallel, elongated guide and support means (13); and

- a traverse assembly (14), which is movable along the guide and support means (13) and in the longitudinal direction (L) of the table top (6), and which extends across the table top (6) perpendicularly to said longitudinal direction (L) and comprises a squeezing means in the form of a squeeze roll (24), which extends across at least the major portion of the width (b) of the table top (6), said squeeze roll (24) being vertically adjustable to enable it to be brought between a first, inactive position, where the squeeze roll (24) clears and does not interact with the table surface (7) and/or said first and second substrates (60, 61) laid out on the table surface (7), and a second, active position, where the squeeze roll (24) interacts with the table surface (7) and/or said first and second substrates (60, 61) laid out on the table surface (7);

wherein the traverse assembly (14) is adapted to be moved along the guide and support means (13) during the joining operation, with the squeeze roll (24) in the active position with said substrates (60, 61) between itself and the table surface (7) while the squeeze roll (24) is caused to rotate about its axis of rotation and to exert a squeezing force upon the substrates (60, 61),

- heating means (33; 33'), which are adapted to bring the shell surface (27) of the squeeze roll (24) to a desired temperature or a desired temperature range during the joining operation, said desired temperature or desired temperature range exceeding the temperature of the air surrounding the squeeze roll (24),

characterized in that said heating means (33; 33') are disposed inside the squeeze roll (24) for said heating of the shell surface (27), wherein squeezing of the squeeze roll is performed intermittently in the flatbed applicator and that all surface areas on the shell surface are within the predetermined temperature range when initiating the application operation in the flatbed applicator.

2. The flatbed applicator (1) according to claim 1, characterized in that said heating means (33; 33') are adapted to bring the shell surface (27) of the squeeze roll (24) to a desired temperature or a desired temperature range between 25 °C and 250 °C.

3. The flatbed applicator (1) according to claim 1 or 2, characterized in that said heating means (33; 33') are disposed inside the squeeze roll (24) for said heating of the shell surface (27).

4. The flatbed applicator (1) according to claim 3, characterized in that said heating means (33; 33') are disposed at a radial distance from the axis of rotation of the squeeze roll (24) that is greater than or equal to 0.8 times the radius of the squeeze roll (24).

5. The flatbed applicator (1) according to claim 4, characterized in that said heating means (33; 33') are disposed at a radial distance from the axis of rotation of the squeeze roll (24) that is greater than or equal to 0.9 times the radius of the squeeze roll (24).

6. The flatbed applicator (1) according to any one of the claims 3-5, characterized in that said heating means comprises one or several heating wires (33; 33').

7. The flatbed applicator (1) according to claim 6, characterized in that said heating means comprise one or several heating wires (33; 33') in grooves having a V-shaped cross- section.

8. The flatbed applicator (1 ) according to claim 6, characterized in that said one or several heating wires (33') run(s) in straight grooves (35'), which are parallel to the axis of rotation of the squeeze roll (24) and extend from a first end (25) to a second end (26) of the squeeze roll (24).

9. The flatbed applicator (1 ) according to claim 6, characterized in that said one or several heating wires (33) run(s) in helical grooves (35, 36) about the axis of rotation of the squeeze roll (24).

10. The flatbed applicator (1) according to claim 8, characterized in that said one or several heating wires (33) comprise(s) a first conductor portion (37), which runs in a first helical groove (35) from the first end (25) to the second end (26) of the squeeze roll (24), and a second conductor portion (38), which is arranged in series with the first conductor portion (37) and runs in a second helical groove (36) from the second end (26) of the squeeze roll (24) and back to the first end (25) thereof, said second helical groove (36) being parallel to the first helical groove (35).

11. The flatbed applicator (1) according to any one of the claims 6-9, characterized in that it comprises a control device (43), which comprises a control unit (45) for applying and controlling current through said one or several heating wires (33; 33') to maintain the temperature of the shell surface (27) at said desired temperature or within said desired temperature range.

12. The flatbed applicator (1) according to claim 10, characterized in that the squeeze roll (24) comprises an overheating protector (39), which is adapted to interrupt the current through said one or several heating wires (33; 33') when the temperature in the squeeze roll (24) exceeds a predetermined temperature.

13. The flatbed applicator (1) according to any one of the claims 10-1 1, characterized in that the control device (43) comprises one or several temperature transmitters (46) for direct or indirect measurement of the temperature of the shell surface (27).

14. The flatbed applicator (1) according to claim 12, characterized in that said one or several temperature transmitters comprise(s) one or several sensors (46) for detecting thermal radiation from the shell surface (27) of the squeeze roll (24), said one or several sensors (46) being disposed such that they have an unobstructed field of view to the shell surface (27).

15. The flatbed applicator (1) according to claim 13, characterized in that said one or several sensors (46) is/are adapted to transmit actual temperature values of the temperature of the shell surface (27) to said control unit (45), wherein the control unit (45) is adapted to control the energy supplied to the heating means (33), so that the temperature of the shell surface (27) is maintained at said desired temperature or within said desired temperature range.

16. The flatbed applicator (1) according to any one of the claims 6-14, characterized in that the squeeze roll (24) comprises a circularly cylindrical tubular member (28), axle journals (29) which are disposed at the ends of the tubular member (28), a first layer (30) of an elastic material surrounding the tubular member (28), a second layer (31) of an elastic material surrounding the first layer (30), and a third layer (32) of an elastic material surrounding the second layer (31), said third layer (32) forming the shell of the squeeze roll (24) and having a hardness that is less than the hardness of the first layer (30) and the second layer (31), wherein said one or several heating wires (33) are disposed in recesses (34) in the first layer (30) and are covered by the second layer (31).

17. The flatbed applicator (1) according to claim 15, characterized in that said first layer (30) and said second layer (31) consist of EPDM rubber or silicone rubber, having a hardness in the range of 70-80 degrees Shore, and that said third layer (32) consists of an EPDM rubber or a silicone rubber with textile fibres mixed into it, said third layer (32) having a hardness in the range of 35-55 degrees Shore.

18. The flatbed applicator (1) according to claim 16, characterized in that said layers (30, 31, 32) are joined together by vulcanizing.

19. A method for joining or laminating a first, flat substrate (60) and a second, thin, flat substrate ( 1), comprising the steps of:

a) placing the first substrate (60) on a flat table surface (7);

b) placing the second substrate (61) on top of the first substrate (60);

c) bringing a squeezing means in the form of a squeeze roll (24) to a desired temperature or a desired temperature range by heating, said desired temperature or desired temperature range exceeding the temperature of the air surrounding the squeeze roll (24), said squeeze roll (24) being vertically adjustable to enable it to be brought between a first, inactive position, where the squeeze roll (24) clears and does not interact with the table surface (7) and/or said first and second substrates (60, 61) laid out on the table surface (7), and a second, active position, where the squeeze roll (24) interacts with the table surface (7) and/or said first and second substrates (60, 61) laid out on the table surface (7);

d) bringing the squeeze roll (24) to the inactive position and moving it across the

substrates laid out on the table surface (7);

e) bringing the squeeze roll (24) to the active position, so that said substrates (60, 61) are clamped between the squeeze roll (24) and the table surface (7); and

f) moving the squeeze roll (24), in its active position, across the table surface (7) and the substrates (60, 61) laid out on the table surface (7), so that the substrates (60, 61) are joined together with each other under the influence of the pressure and heat from the heated squeeze roll (24) and that said heating means (33; 33') are disposed inside the squeeze roll (24) for said heating of the shell surface (27), wherein squeezing of the squeeze roll is performed intermittently in the flatbed applicator and that all surface areas on the shell surface are within the predetermined temperature range when initiating the application operation in the flatbed applicator.