DE20004811U1 - Device for applying hot melt adhesives - Google Patents

Description

TERMEER STEINMEISTER & PARTNER GBR

PATENT ATTORNEYS - EUROPEAN PATENT ATTORNEYS

Dr. Nicolaus ler Meer, Dipl.-Chem. Helmut Sieinmeister, Dipl.-Ing.

Peter Urner, Dipl.-Phys. Manfred Wiebusch

Gebhard Merkle, Dipl.-Ing. (FH)

Mauerkircherstrasse 45 Artur-Ladebeck-Strasse 51

D-81679 MUNICH D-3361 7 BIELEFELD

HAU POl /0OG

St/fü/li

14.3.2000

H & H Maschinenbau GmbH

Industrieweg 6

32457 Porta Westfalica

"DEVICE FOR APPLYING HOT MELT ADHESIVES"

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"DEVICE FOR APPLYING HOT MELT ADHESIVES"

The invention relates to a device for applying hot melt adhesive or other viscous masses, with an adhesive container having an outlet opening on the lower side, an application roller below the outlet opening and a device for dosing the adhesive to be applied.

Devices for applying viscous masses and in particular hot melt adhesives using application rollers have been known in various designs for a long time.

In a simple design, similar to printing machines, molten hot melt adhesive is introduced by means of pipes into the open, wedge-shaped space above a roller gap between two parallel rollers, an application roller and a metering roller. Such devices are suitable for larger application thicknesses with relatively rapid adhesive throughput, but not for applying very thin layers in the range of a few μπα. With such thin layers, the adhesive remains above the roller gap for a relatively long time, so that in the conventional, completely open system it oxidizes and thus changes its properties and can ultimately no longer be processed.

There are therefore also systems in which a heated adhesive container is located above an applicator roller. This container contains a larger supply of adhesive that is less affected by oxidation and cooling. The adhesive is metered using a metering scraper that is positioned against the circumference of the applicator roller in the manner of a doctor blade commonly used in the printing industry. Devices of this type also cause considerable problems when applying thin layers in the range of a few μιλ, for example 9 to 12 μιδ. Adhesive manufacturers have not yet succeeded in producing hot melt adhesives that are completely free of granular particles in the range of a few μιλ in diameter, or in sieving out such granular particles. Furthermore, particles can get into the system from outside. This means that the particles gradually settle in the dosing gap between the application roller and the dosing scraper, so that no adhesive can pass through the dosing gap. The particles in the dosing gap are characterized by

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as clearly visible stripes in the applied layer.

Therefore, there is currently no application system that makes it possible to apply a completely uniform adhesive layer with a thickness of just a few μm without leaving streaks.

The invention is therefore based on the object of creating a device of the above type which ensures a completely uniform application of adhesive layers even in the range of a small thickness of a few μηι.

This object is achieved according to the invention in a device of the above type in that the metering device comprises a metering roller arranged parallel to the application roller, forming an adjustable roller gap with the latter and rotatable together with the application roller in the opposite direction of rotation to the latter.

By adjusting the width of the roller gap, the thickness of the applied layer can be set very precisely. If there are granular particles in the adhesive mass, these are not held in place, unlike with a doctor blade, but are crushed by the interaction of the two rollers in the roller gap and carried through the gap. The aforementioned streaking in the applied layer therefore does not occur.

The peripheral surface of the application roller is completely smooth and should be particularly hard.

Preferably, the metering roller is displaceable substantially perpendicular to its longitudinal axis and substantially in a horizontal direction to adjust the roller gap.

The gaps between the edges of the lower outlet opening of the adhesive container and the corresponding outer sides of the respective rollers on both sides of the pair of rollers formed by the application roller and the metering roller are preferably closed by closure flaps which extend parallel to the two rollers. These closure flaps are preferably pivotable about their longitudinal axis between a position in which they tightly close the aforementioned gap and a further position in which

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they leave a small, adjustable gap between them and the outside of the two rollers. This prevents the two rollers, which naturally move downwards in the common roller gap and upwards on the opposite outside, from stripping off excess adhesive on the outside of the closure flaps.

The closure flaps preferably have a closure edge that can be placed against a surface line of the circumference of the respective roller and a sealing surface that rests against a seal on the underside of the adhesive container. When the closure flaps rotate about their longitudinal axis, the sealing surface, which preferably runs concentrically to the axis of rotation in the upper area, remains in contact with the seal, while the tapered closure edge can form a fine gap with the surface line of the corresponding roller.

The closure flaps preferably have levers projecting perpendicular to their longitudinal axes, to which control cylinders act which control the very slight rotation of the closure flaps between two end positions predetermined by stops.

The metering roller is preferably mounted in bearing rings which have an eccentric bore and are in turn rotatably mounted in bores in the bearing housing. By rotating these bearing rings, the metering roller can be adjusted relative to the application roller. The bearing rings can be rotated, for example, by providing a worm gear profile on the circumference of the bearing rings, into which a worm rotatably mounted in the bearing housing engages. The adhesive container preferably has a lid so that unnecessary cooling and increased oxygen access to the adhesive are avoided. It is even possible to provide a protective gas above the adhesive level.

Further features and advantages of the invention emerge from the subclaims.

In the following, preferred embodiments of the invention are explained in more detail with reference to the accompanying drawings.

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Fig. 1 is a schematic vertical section through an adhesive container with dosing system;

Fig. 2 is an enlarged partial view of Figure 1 in a vertical section;

Fig. 3 is a further enlarged partial view of Figure 2.

Fig. 1 shows a vertical section of an adhesive container 10 which essentially has the shape of a funnel and has an outlet opening 12 on the lower side. The side walls designated 14 and 16 and shown in Fig. 1 converge in several steps at an angle downwards to a passage 18 and from this passage 18 diverge again at an angle. Below the passage 18 there is an application roller 20 which runs perpendicular to the plane of the drawing in Fig. 1 and next to this there is a metering roller 24 which forms an essentially vertical roller gap 22 with the application roller and which also extends perpendicular to the plane of the drawing in Fig. 1. The entire outlet opening 12 has the shape of an elongated rectangle in horizontal cross section, the longer axis of which runs perpendicular to the plane of the drawing in Fig. 1.

There are holes 26, 28, 30, 32, 34, 36 in the side walls 14, 16 of the adhesive container 10. These holes serve to accommodate heating cartridges (not shown) which heat the adhesive container to such an extent that adhesive blocks (not shown) placed in the adhesive container can be melted and brought to the correct application temperature.

The axes of the application roller 20 and the metering roller 24 are at least substantially at the same height, and the roller gap 22 can be changed by moving the metering roller 24 in a horizontal direction from right to left in the figure and thus perpendicular to its longitudinal axis. This will be explained in more detail later.

Between the outer sides of the application roller 20 and the metering roller 24 and the edges of the outlet opening 12 there are unmarked gaps which are closed by means of closure flaps 38,40. The two closure flaps 38,40 can each be slightly pivoted about an axis 42,44. These axes 42,44 extend parallel to the two rollers 20,24 on the

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both outer sides of this pair of rollers. The closure flaps 38,40 have wedge-shaped, tapered closure edges 46,48 (see also Figure 2) on the inner sides facing the two rollers 20,24 and sealing surfaces 50,52 on the essentially opposite outer surfaces facing the edges of the outlet opening 12, which run essentially concentrically to the axes 42,44 and rest against the underside of the edges of the outlet opening 12. In the wedge-shaped spaces formed by the two sealing surfaces 50,52 and the bottom of the adhesive container 10 there are sealing strips 54,56, approximately in the form of rubber strips with a circular cross-section. To support these sealing strips, retaining brackets 58,60 are attached to the lower outer corners of the container bottom. On their unmarked horizontal lower legs there are pressure pieces 62,64 which can be moved with the aid of unmarked screws in such a way that they press the sealing strips 54,56 into the wedge-shaped space formed between the container bottom and the respective sealing surface 50,52 of the closure flap.
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The application roller 20 and the metering roller 24 are driven in opposite directions of rotation by a drive mechanism (not shown). The direction of rotation is indicated by the arrows (not shown) in Figure 1 or Figure 2. Accordingly, a downward movement of the peripheral surfaces occurs in the roller gap 22, while an upward movement takes place on the opposite outer sides. During the joint downward movement of the roller surfaces, adhesive is carried along by the application roller 20. This adhesive is applied to the underside of the application roller 20 onto a material 66 to be coated, which runs between the application roller 20 and a pressure roller 68 arranged below the application roller.

During operation of the system, i.e. during rotation of the two rollers 20 and 22, the two sealing edges 46 and 48 of the sealing flaps 38 and 40 are located at a small distance from the surface of the two rollers 20, 22. The distance must only be a few μm, but it must be ensured that the adhesive remaining on the two rollers 20, 24 is not stripped off by the sealing edges 46, 48, but returns to the adhesive bath inside the adhesive container 10. Only when the system is switched off and the two rollers 20, 24 are no longer rotated by the drive (not shown), the gap between the sealing edges 46, 48 is closed.

closing edges 46,48 and the peripheral surface of the rollers 20,24. This is done by the closing flaps 38,40 being slightly

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Angles can be rotated. For this purpose, they are connected to levers 70,72 which project to the right and left, i.e. outwards, and which extend radially in relation to the rotation axes of the closure flaps. Further levers 74,76 are firmly connected to these levers 70, 72, the end regions of which point diagonally upwards and outwards are pivotally connected to piston rods 82,84 of control cylinders 86,88 by means of axes 78,80. The control cylinders 86,88 are firmly connected at their upper ends, opposite the axes 78,80, to side parts of the machine frame (not shown). Upper and lower stops 94,96 and 98,100, which interact with the levers 74,76, are also attached to these side parts 90,92. The stops 94,96 and 98,100 thus determine the pivoting angle of the closing flaps 38,40 between the open and closed positions.

The layer thickness of the adhesive to be transferred results, as already mentioned, from the width of the roller gap 22 between the application roller 20 and the metering roller 24. To adjust this gap, the metering roller 24 can be adjusted in a horizontal direction according to a double arrow shown in Figure 2. It is thereby displaced transversely to its axis of rotation, as can be seen from Figure 2. This is done in the following way.

Bearing pins (not shown) at both ends of the metering roller 24 are mounted in an eccentric bore of a bearing ring 104, which in turn is arranged to rotate in a bore (not shown) of the bearing housing. To rotate the bearing ring 104, there is a worm wheel profile 106 on its circumference, into which a worm 108 (Figure 3) rotatably mounted in the bearing housing engages. The worm 108 has a head 110 located outside the bearing housing, which in the example shown in Figure 2 is equipped with a hexagon socket for attaching a tool.

By rotating the screw 108, the bearing ring 104 is rotated, and thereby the position of the axis of the metering roller mounted in the eccentric bore 102 of the bearing ring is shifted.

In addition, some parts that have not been discussed so far but are shown in the drawing should be pointed out.

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The adhesive container 10 is closed by a schematically indicated lid 112. This prevents rapid cooling of the adhesive in the adhesive container and oxidation of the adhesive. In the adhesive bath in the area of the outlet opening there is a temperature sensor 114 which senses the adhesive temperature and feeds it to a control (not shown) of the heating cartridges in the bores 26, 28, 30, 32, 34, 36.

The two levers 70,72 on the one hand and 74,76 on the other hand are connected by screws which are not separately marked.
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The stops 94,96 and 98,100 are formed by countered threaded bolts, which enable an adjustment of the pivoting of the levers 74,76.

The cylinders 86,88 are preferably pneumatic cylinders. 15

Claims (12)

1. Device for applying hot melt adhesive or other viscous masses, with an adhesive container (10) which has an outlet opening (12) on the lower side, an application roller (20) below the outlet opening and a metering device for metering the applied adhesive, characterized in that the metering device comprises a metering roller (24) arranged parallel to the application roller (20), forming an adjustable, essentially vertical roller gap (22) with the latter and which can be rotated together with the application roller (20) in the opposite direction of rotation to the latter. 2. Device according to claim 1, characterized in that the application roller (20) has a smooth, hard surface. 3. Device according to claim 1 or 2, characterized in that the metering roller (24) is displaceable substantially perpendicular to its longitudinal axis and substantially horizontally for adjusting the roller gap (22). 4. Device according to one of claims 1 to 3, characterized in that pivotable closure flaps (38, 40) are provided on both sides of the roller pair formed by the application roller (20) and the metering roller (24), which close the spaces between the roller pair and the edges of the outlet opening (12). 5. Device according to claim 4, characterized in that the closure flaps (38, 40) are adjustable between a position which completely closes the intermediate spaces and a position which opens a gap to the outer sides of the rollers (20, 24). 6. Device according to claim 5, characterized in that the closure flaps (38, 40) are rotatable about axes running parallel to the pair of rollers (20, 24). 7. Device according to one of claims 4 to 6, characterized in that the closure flaps (38, 40) have a closure edge (46, 48) which can be placed against a surface line of the circumference of the respective roller (20, 24) and a sealing surface (50, 52) which rests against a seal on the underside of the adhesive container (10). 8. Device according to one of claims 5 to 7, characterized in that levers (70, 72) projecting perpendicularly to their axes of rotation are attached to the closure flaps (38, 40) and can be pivoted about the longitudinal axis of the closure flaps (38, 40) by means of control cylinders (86, 88). 9. Device according to claim 8, characterized in that the rotational movement of the closure flaps (38, 40) is limited to a small angle by stops (94, 96, 98, 100). 10. Device according to one of the preceding claims, characterized in that the metering roller (24) is mounted in bearing rings (104) with eccentric bores (102), which bearing rings are rotatably mounted in bores of the bearing housing. 11. Device according to claim 10, characterized in that the bearing rings (104) have a worm gear toothing (106) on the circumference and that a rotatable worm (108) is mounted in the machine frame, which is in engagement with the worm gear toothing. 12. Device according to one of the preceding claims, characterized in that the adhesive container (10) is closed by a lid (112).