GB2034203A

GB2034203A - Applicator Bar

Info

Publication number: GB2034203A
Application number: GB7940342A
Authority: GB
Original assignee: TBA Industrial Products Ltd
Current assignee: TBA Industrial Products Ltd
Priority date: 1978-11-22
Filing date: 1979-11-21
Publication date: 1980-06-04

Abstract

A comb applicator bar for applying liquid or paste coating compositions to a moving substrate in sheet form comprises a bar 3 having a plurality of identical parallel grooves 4 in its surface, the grooves being of non- uniform depth, so that the amount of composition applied can be adjusted by rotating the bar about its axis. <IMAGE>

Description

SPECIFICATION Improvements in and Relating to Coating Apparatus This invention relates to the application of liquid or paste coating materials to a sheet substrate. It is particularly applicable to the coating of substrates in the form of elongate webs of indefinite length.

Coating substrates of uniform thickness and/or surface characteristics is reasonably straightforward. A simple doctor blade or roller nip can be used, either in the form of a straight edge device, or in the form of a comb applicator which applies discrete stripes of coating materitial. The stripes are subsequently caused to flow into one another to form a uniform layer.

Whilst the comb technique is effective for irregular substrates, since it applies stripes of coating material regardless of the thickness of the substrates, it is not readily adjustable. The slots in the comb, or the grooves in a comb roller are not adjustable and even if the comb is provided with an adjustable plate to set the slot depth, it is difficult to obtain accurate settings across the width of the comb.

The present invention provides a comb applicator which in use is mounted in nonrotating, sliding contact relation to a substrate to be coated with liquid or paste coating material, the applicator comprising a bar having a plurality of substantially identical parallel grooves defined in its surface, said grooves being of non-uniform depth, so that in use the amount of material applied can be adjusted by rotation of the bar about its axis.

Preferably the bar is cylindrical and the grooves are eccentrically-disposed relative to the axis of the bar, said eccentricity preferably being such as to confer on them a depth which varies relative to the surface of the bar from zero to a maximum at some other point on the bar's circumference.

The applicator bar of the invention is preferably mounted so that it can be easily rotated relative to its longitudinal axis to apply stripes of coating material of a desired size. In this respect, unlike the adjustable or non-adjustable comb, it is possible to set the groove depth by simply rotating the bar about its axis; no precision measurement is necessary to achieve the same groove depth over the width of the substrate.

Unlike the comb roller, a single bar can accommodate the whole range of stripe sizes required in practice. The grooves as seen in plan may be square or v-shaped.

Where the substrate is irregular in some respects, for example, as is a conveyor belt carcase impregnated with a PVC material which has subsequently been gelled, the applicator bar of the invention may be used to apply a final surface coating of the same or another PVC to one side of the carcase, without the problems of control and adjustability encountered with prior art applicators.

A particularly preferred arrangement is one in which coatings are simultaneously applied to both sides of a substrate. This can be accomplished by using two horizontally spaced bars, one on each side of the substrate which is then caused to travel in a substantially vertical path between them. This technique is especially useful in conveyor belt manufacture.

In order that the invention be better understood, a preferred embodiment of it will now be described by way of example with reference to the accompanying drawing in which Figure 1 a is a plan view of part of an one applicator bar according to the invention; Figure 1 b is a plan view of another bar according to the invention; Figure 2 is a cross-sectional side view of the bar of Figure 1 a or 1 b on line AA of the latter Figure; Figure 3 shows the bar of Figure 2 in use.

In Figures 1 a and 1 b a cylindrical bar 3 has a plurality of equally spaced parallel grooves 4 along its length. The grooves differ only in that Figure 1 a has 'square' grooves; Figure 1 b shows "V" grooves. Each groove is eccentric with respect to the longitudinal axis of the bar, so that as shown, the groove depth varies from one side of the bar to the other, (although as is clear from Figure 2, there is a line of symmetry).

In Figure 2, the groove 4 has zero depth at 5 on the circumference and a maximum depth is the vicinity of 6. The use of the applicator bar is illustrated by Figure 3 in which the bar is shown in running contact with a conveyor belt carcase 7. A PVC plastisol, 8 is applied to the carcase just ahead of the bar, referring to the direction of motion indicated by an arrow and stripes of the PVC material appear downstream of the bar, only one such stripe 9 being shown in the Figure in question, of course. It will be clear that the depth of the size of the stripe 9 is a function of the groove depth at point of contact with the carcase 7 and any desired size can be selected by simply rotating the bar about its axis, subject to the constraints imposed by the geometry of the grooves in this particular example.

It will be appreciated that this arrangement may be turned on its side so that the belting carcase travels in a vertical path. Its other face could then be simultaneously coated by means of a similar applicator bar mounted parallel to the first one.

Claims

1. A comb applicator which in use is mounted in non-rotating, sliding contact relation to a substrate to be coated with liquid or paste coating material, the applicator comprising a bar having a pluraltiy of substantially identical parallel grooves defined in its surface, said grooves being of nonuniform depth, so that, in use, the amount of material applied can be adjusted by rotation of the bar about its axis.

2. A comb applicator according to claim 1 wherein the bar is cylindrical and the grooves are are eccentrically-disposed relative to the axis of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in and Relating to Coating Apparatus This invention relates to the application of liquid or paste coating materials to a sheet substrate. It is particularly applicable to the coating of substrates in the form of elongate webs of indefinite length. Coating substrates of uniform thickness and/or surface characteristics is reasonably straightforward. A simple doctor blade or roller nip can be used, either in the form of a straight edge device, or in the form of a comb applicator which applies discrete stripes of coating materitial. The stripes are subsequently caused to flow into one another to form a uniform layer. Whilst the comb technique is effective for irregular substrates, since it applies stripes of coating material regardless of the thickness of the substrates, it is not readily adjustable. The slots in the comb, or the grooves in a comb roller are not adjustable and even if the comb is provided with an adjustable plate to set the slot depth, it is difficult to obtain accurate settings across the width of the comb. The present invention provides a comb applicator which in use is mounted in nonrotating, sliding contact relation to a substrate to be coated with liquid or paste coating material, the applicator comprising a bar having a plurality of substantially identical parallel grooves defined in its surface, said grooves being of non-uniform depth, so that in use the amount of material applied can be adjusted by rotation of the bar about its axis. Preferably the bar is cylindrical and the grooves are eccentrically-disposed relative to the axis of the bar, said eccentricity preferably being such as to confer on them a depth which varies relative to the surface of the bar from zero to a maximum at some other point on the bar's circumference. The applicator bar of the invention is preferably mounted so that it can be easily rotated relative to its longitudinal axis to apply stripes of coating material of a desired size. In this respect, unlike the adjustable or non-adjustable comb, it is possible to set the groove depth by simply rotating the bar about its axis; no precision measurement is necessary to achieve the same groove depth over the width of the substrate. Unlike the comb roller, a single bar can accommodate the whole range of stripe sizes required in practice. The grooves as seen in plan may be square or v-shaped. Where the substrate is irregular in some respects, for example, as is a conveyor belt carcase impregnated with a PVC material which has subsequently been gelled, the applicator bar of the invention may be used to apply a final surface coating of the same or another PVC to one side of the carcase, without the problems of control and adjustability encountered with prior art applicators. A particularly preferred arrangement is one in which coatings are simultaneously applied to both sides of a substrate. This can be accomplished by using two horizontally spaced bars, one on each side of the substrate which is then caused to travel in a substantially vertical path between them. This technique is especially useful in conveyor belt manufacture. In order that the invention be better understood, a preferred embodiment of it will now be described by way of example with reference to the accompanying drawing in which Figure 1 a is a plan view of part of an one applicator bar according to the invention; Figure 1 b is a plan view of another bar according to the invention; Figure 2 is a cross-sectional side view of the bar of Figure 1 a or 1 b on line AA of the latter Figure; Figure 3 shows the bar of Figure 2 in use. In Figures 1 a and 1 b a cylindrical bar 3 has a plurality of equally spaced parallel grooves 4 along its length. The grooves differ only in that Figure 1 a has 'square' grooves; Figure 1 b shows "V" grooves. Each groove is eccentric with respect to the longitudinal axis of the bar, so that as shown, the groove depth varies from one side of the bar to the other, (although as is clear from Figure 2, there is a line of symmetry). In Figure 2, the groove 4 has zero depth at 5 on the circumference and a maximum depth is the vicinity of 6. The use of the applicator bar is illustrated by Figure 3 in which the bar is shown in running contact with a conveyor belt carcase 7. A PVC plastisol, 8 is applied to the carcase just ahead of the bar, referring to the direction of motion indicated by an arrow and stripes of the PVC material appear downstream of the bar, only one such stripe 9 being shown in the Figure in question, of course. It will be clear that the depth of the size of the stripe 9 is a function of the groove depth at point of contact with the carcase 7 and any desired size can be selected by simply rotating the bar about its axis, subject to the constraints imposed by the geometry of the grooves in this particular example. It will be appreciated that this arrangement may be turned on its side so that the belting carcase travels in a vertical path. Its other face could then be simultaneously coated by means of a similar applicator bar mounted parallel to the first one. Claims

2. A comb applicator according to claim 1 wherein the bar is cylindrical and the grooves are are eccentrically-disposed relative to the axis of the bar.

3. A comb applicator according to claim 1 or claim 2 wherein the depth of the grooves varies relative to the surface of the bar from zero to a maximum at some other point on the surface of the bar.

4. A comb applicator according to any preceding claim, wherein the grooves are of square or V-shaped section.

5. A comb applicator substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.

6. A method of applying coating material to one or both sides of a conveyor belt carcase substantially as described with reference to the accompanying drawings.