DEVICE AND METHOD FOR APPLYING ADHESIVE TO A SUBSTRATE

Abstract

A device for applying adhesive to a substrate, having an application roller that is rotatable about an axis, an installation for dispensing adhesive to a circumferential area of the application roller, a dispensing region of the application roller for dispensing adhesive from the application roller, and having a doctor blade, wherein the dispensing region for adhesive in the rotation direction of the application roller is located behind the installation for dispensing the adhesive to the application roller and ahead of the doctor blade. In such a device it is provided that the application roller is rotatable about a vertical axis and the excess adhesive wiped by the doctor blade reaches a collection installation that is located below the doctor blade. In a method for applying adhesive to a substrate, excess adhesive that has not been applied to the substrate is disposed of.

Claims

1. A device for applying adhesive to a substrate, comprising: an application roller that is rotatable about an axis; an installation for dispensing adhesive to a circumferential area of the application roller; a dispensing region of the application roller for dispensing adhesive from the application roller; and a doctor blade for wiping excess adhesive from the application roller; wherein the dispensing region for adhesive in the rotation direction of the application roller is located behind the installation for dispensing the adhesive to the application roller and ahead of the doctor blade; and wherein the application roller is rotatable about a vertical axis and the excess adhesive wiped by the doctor blade reaches a collection installation that is located below the doctor blade.

2. The device according to claim 1, wherein the application roller is configured as a drivable cylinder.

3. The device according to claim 1, wherein the installation for dispensing adhesive is configured as a nozzle.

4. The device according to claim 4, wherein the nozzle is a slot die.

5. The device according to claim 4, wherein the slot die has a vertical slot, and wherein the extent of the vertical slot is adjustable.

6. The device according to claim 5, wherein the extent of the vertical slot is non-modifiable at a lower end and is modifiable in an upper region.

7. The device according to claim 4, wherein the slot die is mounted in such a manner that the spacing from the application roller is modifiable.

8. The device according to claim 1, wherein a rotation direction of the application roller is counter to a displacement direction of the substrate.

9. The device according to claim 8, wherein the displacement direction of the substrate is a rectilinear and horizontal displacement direction of the substrate.

10. The device according to claim 4, wherein the slot die and the doctor blade are diametrically located.

11. The device according to claim 4, wherein the slot die and the doctor blade mutually enclose a circular angle of about 160° to about 200°.

12. The device according to claim 11, wherein the circular angle is about 180°.

13. The device according to claim 4, wherein a dispensing region of the slot die and a vertical in relation to a surface of the substrate that is to be provided with adhesive enclose a circular angle of about 80° to about 100°, and wherein a wiping region of the doctor blade and the vertical in relation to the surface of the substrate that is to be provided with adhesive enclose a circular angle of about 60° to about 120°.

14. The device according to claim 13, wherein the dispensing region and the vertical enclose a circular angle of about 90°, and wherein the wiping region and the vertical enclose a circular angle of about 90°.

15. The device according to claim 1, wherein the application roller, the installation for dispensing adhesive, and the doctor blade are mounted in a first support, and wherein the first support is horizontally guided in a second support and is spring-mounted horizontally in a direction of contact of the application roller with the substrate.

16. The device according to claim 1, wherein the application roller is heatable by means of a heating installation.

17. The device according to claim 16, wherein the application roller, the installation for applying adhesive, the doctor blade, and the heating installation are mounted in an overhung position on the same side.

18. A method for applying adhesive to a substrate by means of a device according to claim 1, the method comprising: applying adhesive to the application roller as the application roller is rotating; transferring adhesive from the application roller to the substrate as the substrate is conveyed in a rectilinear manner along the application roller; wiping excess adhesive that has not been applied to the substrate from the application roller; and disposing of the excess adhesive.

19. The method according to claim 18, further comprising applying adhesive by means of the application roller counter to a transportation direction of the substrate with a circumferential speed of the application roller being about one to about two times a speed of the substrate.

20. The method according to claim 18, wherein the exit of adhesive from the installation for dispensing adhesive is cycled in such a manner that the application of adhesive to the substrate commences with a leading edge of the substrate and ends with a trailing edge of the substrate, and wherein a width of the application of adhesive to the application roller corresponds to the thickness of the substrate.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0040] The invention is visualized in the figures by means of an exemplary embodiment of the invention in a schematic illustration, without being limited to this exemplary embodiment.

[0041] FIG. 1 shows a plan view of a device according to the invention, having a transportation system and substrates that are conveyed by means of the transportation system.

[0042] FIG. 2 shows an enlarged fragment of the region of the application roller that is illustrated in the context of the device according to FIG. 1.

[0043] FIG. 3 shows a side view of the device according to FIG. 1, viewed from the side of the substrate.

[0044] FIG. 4 shows an enlarged fragment A of FIG. 3, of a rearward peripheral region of the application roller with the doctor blade.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0045] By means of the device 20, which is also referred to as the adhesive applicator, adhesive 8 is applied by means of a slot die 1 to a rotating heatable application roller 5 that is configured as a hollow cylinder and by counter rotation transfers the adhesive 8 to a face 25 of a moving cuboid substrate 6, and wherein adhesive which after the transfer of adhesive to the substrate 6 still adheres to the application roller 5 is wiped off by means of a doctor blade 11, this wiped adhesive 15 no longer being returned to the device.

[0046] The device 20 and a transportation system 7 for conveying the substrate 6 are illustrated in FIG. 1. The slot die 1 is supplied with adhesive from an adhesive-application apparatus 21 by way of a tube 2. The slot die by way of a longitudinal guide 4 is held in a first support 3. By way of the longitudinal guide 4 the potential for displacing the slot die 1 in the longitudinal direction, transversely to the axial direction of the heatable application roller 5, is achieved. On account thereof, the spacing of the nozzle slot from the application roller 5 can be modified. Furthermore, in the case of a large spacing it is possible for a cover to be attached over the nozzle slot, by way of which cover blocking of the nozzle slot by cross-linked PUR adhesive can be prevented in particular with PUR adhesive. This is required when an edge-banding machine, in the context of which the device 20 is being used, is not operated for a prolonged period and no adhesive is being processed. The longitudinal guide 4 for mounting the slot die 1 is designed such that the slot die 1 can be readily dismantled for cleaning and maintenance purposes. The application roller 5 is located so as to be approximately parallel, in particular parallel with the nozzle slot of the slot die 1. Said application roller 5 is drivable by a regulated motor, and transports the adhesive 8, specifically an adhesive film 8, which is applied by the slot die 1, toward a substrate 6.

[0047] Heating of the application roller 5 is performed by a fixedly installed stationary heating element which is to be found inside the interior of the application roller 5. The heating element is heated by way of heating cartridges. A liquid heat transfer medium is employed for transferring the heat from the heating element to the rotating application roller 5. The application roller 5 is mounted in an overhung position, and the heating element is likewise mounted in an overhung position and is supported on the mounting side.

[0048] The motor for driving the application roller 5, and the heating cartridges of the application roller 5, are connected to a controller 22 of the adhesive-application apparatus 21.

[0049] The transportation system 7 is driven by an edge-banding machine. This transportation system 7 has, for example, upper and lower belt tapes and rollers, the substrate being held and transported therebetween. The substrate 6 herein is transported by the transportation system 7 past the application roller 5. The substrate is clamped between the belt tapes and the rollers in such a manner that the substrate is not laterally displaced even if and when slight transverse forces act on the substrate. The application roller 5 contacts the substrate 6 when the substrate 6 is being transported past the application roller. As is visualized by the arrow 23, the application roller 5 rotates counter to the running direction of the substrate 6, the latter being visualized by the arrow 24, such that the adhesive film 8 is wiped from the application roller 5 and is transferred to that narrow edge, thus that narrow lateral face 25 of the substrate 6 that faces the circumferential face 26 of the application roller 5 and is located parallel with the rotation axis of the application roller 5. The adhesive film 8 by the slot die 1 is applied to the application roller 5 at a width b (see FIG. 3) which corresponds exactly to the thickness of the substrate 6, or is slightly narrower than the latter. On account thereof, almost one hundred percent of the adhesive that is transported on the application roller 5 is stripped when the adhesive is wiped off by the substrate 6. The exit of adhesive from the slot die 1 is cycled by the controller of the adhesive-application apparatus 21 in such a manner that the beginning of the adhesive film commences exactly with the leading edge 9 of the substrate 6, and the end terminates exactly with the trailing edge 10 of the substrate 6. The circumferential speed of the application roller 5 is readjustable. A circumferential speed which corresponds approximately to one to two times the substrate speed is preferred. This guarantees that adhesive is very cleanly transferred from the application roller 5 to the substrate 6. If the circumferential speed of the application roller 5 is modified, this will have an influence on the cycling of the adhesive film 8 at the slot die. The controller 22 of the adhesive-application apparatus 21 automatically adapts the cycling to the new conditions. An application of adhesive that is not continuous on the substrate 6 can also be implemented by way of this type of adhesive application from the slot die 1 by way of the application roller 5 to the substrate 6. Arbitrary application patterns with interruptions in the adhesive can be implemented.

[0050] A further advantage lies in that the adhesive comes into contact with the ambient air only briefly. This reduces the contamination of the adhesive by dust from the environment, and fewer vapors which are released to the ambient air are created. Therefore, the slot die 1 is located such that the application roller 5 has to transport the adhesive only across a short part of the circumference. In the exemplary embodiment this is approximately a quarter of the circumference of the application roller 5.

[0051] In order for the application roller 5, while transferring adhesive to the narrow edge 25 of the substrate 6, to positively contact the substrate 6, said application roller 5 is pressed against the substrate 6 by way of a sprung suspension. The application roller 5 is mounted in the first support 3. The doctor blade 11 is likewise connected to the first support 3. The first support 3 is mounted by way of a linear guide in a second support 12 which is fixedly connected to the machine frame. The first support 3, and thus the application roller 5, are displaceable by the longitudinal guide toward the narrow edge 25 of the substrate 6. A defined pressure by means of springs 13 is exerted by the application roller 5 toward the substrate 6. On account thereof, minor positional deviations of the substrate 6 in the transportation system 7 can additionally be absorbed. In place of the linear guides, the first support 3 could also be suspended in a pivotable manner.

[0052] The application roller 5 is preferably composed of a hardenable material, and is hardened at least in the region of the roller circumference. Alternatively, a surface coating can be employed. On account thereof, the wear on that external face of the application roller 5 that comes into contact with the substrate 6 can be reduced.

[0053] The doctor blade 11 has a doctor knife 14 (FIG. 2) which is connected to the first support 3 by way of a spring steel sheet 27. The doctor knife 14 is set against the circumferential face 26 of the application roller 5 at a slight pressure. Residual adhesive which, once the application roller 5 has transferred the adhesive film to the substrate 6, still adheres to the application roller 5 is wiped off by the doctor knife 14. The wiped adhesive 15 builds up in the forward region of the doctor knife 14 and, once sufficient adhesive has built up, flows in the direction of the rotation axis 28 of the application roller 5, thus downward in the vertical direction. The first support 3 is heated in order to facilitate flowing of the adhesive. Said first support 3 conducts the heat by way of the spring steel sheet 27 to the doctor knife 14. Heat also reaches the wiped adhesive 15 from the heated application roller 5, such that said wiped adhesive 15, following gravity, begins to flow once sufficient wiped adhesive has accumulated.

[0054] The dispensing region of the slot die 1 and a vertical 30 in relation to that surface 25 of the substrate 6 that is to be provided with adhesive 8 enclose an angle of 90°, the wiping region of the doctor blade 11 with this vertical 30 likewise enclosing an angle of 90°.

[0055] It is illustrated in FIG. 3 that the wiped adhesive 15 runs vertically downward, and is collected in a collection trough 16. The collection trough 16 is periodically emptied by hand, and the adhesive is disposed of in particular as residual waste/in-house waste. Almost the entire roller length of the application roller 5 is provided with adhesive if very thick substrates 6 are being processed. In this case, it may happen that the wiped adhesive 15 not only runs down on the doctor knife 14 but also diverts somewhat upward. Therefore, an adhesive deflector 17 (see FIG. 4) is attached to the upper end of the application roller 5. The adhesive deflector 17 is attached between the end of the application roller 5 and a flange 18 of the first support 3. Said adhesive deflector 17 wipes off adhesive which under certain circumstances can reach behind the periphery of the application roller 5, and returns said adhesive back to the doctor knife 14. The flange 18 has an external diameter which corresponds to the diameter of the application roller 5. The doctor knife 14 protrudes beyond the upper periphery of the application roller 5. Said doctor knife 14 herein covers the adhesive deflector 17 and the flange 18 of the first support 3. The doctor knife 14 terminates at a minimum gap on the delimitation face of the first support 3. Adhesive that is caught in this region has to occasionally be removed by hand.

[0056] The width b of the adhesive film 8 is illustrated in FIG. 3. The length of the nozzle slot can be readjusted by the bar 19. Should the substrate 6 be thicker, the length of the nozzle slot is thus enlarged in an upward manner. The lower delimitation of the substrate 6 always remains at the same position. The substrate thickness is modified only in an upward manner. This readjustment of the length of the nozzle slot can be performed by hand or by an actuator. Should the readjustment be performed by an actuator, the latter is thus connected to the controller 22 of the adhesive-application apparatus 21 and is actuated by the latter. The slot die 1 is connected to the controller 22 of the adhesive-application apparatus 21 by way of a cable harness 31. The power for heating the slot die 1, the actuation of the valves for cycling the adhesive output, and the necessary measurement signals are exchanged through the cable harness 31. All heating units of the device 20 are likewise connected to the adhesive-application apparatus 21 and are controlled by the controller of the adhesive-application apparatus 21.