WO2000007742A1

WO2000007742A1 - Coating apparatus

Info

Publication number: WO2000007742A1
Application number: PCT/GB1999/002422
Authority: WO
Inventors: Steven Jacombs; Kevin Haynes
Original assignee: Hayneswood Engineering Sales Limited
Priority date: 1998-08-07
Filing date: 1999-08-06
Publication date: 2000-02-17
Also published as: AU5293699A; GB9817194D0

Abstract

A coating apparatus for coating a continuous roll of substrate (31), for example steel or aluminium in sheet-like form, includes an enclosed reservoir (34) which contains coating material under pressure. The enclose reservoir (34) is mounted in close proximity to an engraved roller (36) and coating material is applied from the enclosed reservoir (34) under pressure onto the surface of the engraved roller (36). The coating material is then transferred from the engraved roller (34) to an application roller (37) which then applies the coating material to the surface of the substrate (31). The application of coating under pressure onto the engraved roller (34) reduces coating wastage and the use of the engraved roller (34) ensures accurate application and removes the necessity for constant monitoring of the gap betwen the roller (34) and the roller (37).

Description

COATING APPARATUS

This invention relates to a coating apparatus and in particular to

coating apparatus for applying a coating to a continuous roll of a sheet-like

metallic substrate (referred to in the art as a coil).

Conventionally a coating is applied to a roll of sheet-like metallic

substrate by passing the substrate around a driven roller. As the substrate

passes around the driven roller, a coating is applied to the surface of the

substrate by one or more coating application rollers mounted such that their

respective circumferential surfaces contact the surface of the substrate as

it passes around the driven roller. The application rollers are mounted such

that their circumferential sur aces are in close proximity to the

circumferential surfaces of respective take up rollers which take up coating

from an open reservoir and transfer this to the application roller for

application to the substrate.

A problem arises with this known apparatus insofar as it is necessary

to continuously monitor and adjust, where necessary, the gap between the

surface of the application roller and the take up roller to ensure that the

correct thickness of coating material is applied and that the coating material

is therefore applied in an accurate manner. A further problem arises with

this known apparatus insofar as due to the manner of take up of coating

from an open reservoir, it is possible for considerable coating material

wastage to occur due to the inaccuracy of this take up. This wastage can

be as much as 10 to 1 5% of the coating material used. A still further problem arises due to the manner of take up of coating material insofar as

it is not usually possible to ensure that the coating material is taken up

evenly by the take up roller and therefore to ensure that an even coating is

eventually applied to the substrate.

It is an object of the present invention to provide a coating apparatus

in which these problems are overcome or at least minimised.

Thus and in accordance with a first aspect of the present invention

there is provided a coating apparatus, particularly for coating a continuous

roll of sheet-like metallic substrate, said apparatus comprising an enclosed

reservoir containing coating material under pressure, an engraved roller

disposed in close proximity to said enclosed reservoir to take up coating

material therefrom and an application roller to take up coating material from

said engraved roller and apply said material to a surface of a substrate.

With this arrangement, with the use of an engraved roller, it is

possible to arrange for the take up of coating material to be (considerably

more) accurate than with conventional apparatus. Furthermore the

application of coating under pressure onto the engraved roller reduces

coating wastage since only the amount of coating required to fill the

engraved pattern is used. Furthermore use of an engraved roller means that

once the engraved roller has been manufactured to particular predetermined

parameters for a particular application, there is no necessity to arrange for

continuous monitoring of a gap between the engraved roller and the

application roller since no gap is necessary as the thickness of coating is controlled by the depth of the engraved pattern.

Preferably one or more doctor blades are provided which wipe the

surface of the engraved roller to remove coating from areas of the roller

other than the engraved pattern and ensure that a uniform depth of coating

is provided in the engraved pattern.

Preferably the reservoir is enclosed by rear, top and bottom walls of

the reservoir and at least a part of the surface of the engraved roller. Most

preferably, the reservoir is enclosed by rear, top and bottom walls of the

reservoir, at least a part of the surface of the engraved roller and said one

or more doctor blades.

Preferably a pair of doctor blades are provided, one depending from

a top wall of the reservoir and the other extending upwardly from a bottom

wall of the reservoir, both blades terminating adjacent the surface of the

engraved roller.

In accordance with a second aspect of the present invention there is

provided a method of applying a coating to a continuous roll of sheet-like

metallic material comprising applying coating material to a surface of an

engraved roller under pressure from an enclosed reservoir of coating

material, transferring the coating material from the engraved roller to an

application roller and applying the coating material from the application roller

to the substrate.

With this method it is possible to ensure the even application of a

coating to a continuous roll of substrate. Preferably the substrate is provided in the form of a continuous roll

and is fed to the application roller, is coated thereby and is then wound

once again into a finished roll.

The second aspect of the invention can include any one or more of

the features of the first aspect of the invention.

The invention will now be described further by way of example only

and with reference to the accompanying drawings in which:-

Fig. 1 shows a diagrammatic representation of one form of

conventional coating apparatus; and

Fig. 2 shows a diagrammatic representation of one form of coating

apparatus according to the present invention.

Referring now to the drawings, there is shown in Fig. 1 a

conventional form of coating apparatus 10 for coating a continuous roll of

substrate 1 1 , for example steel or aluminum, in sheet-like form. The

continuous roll of substrate 1 1 is referred to in the art as a coil. The

substrate 1 1 is fed around the driven roller 12 from a storage roll (not

shown) to a finished roll (not shown). As the substrate 1 1 passes around

the driven roller 1 2 it passes at least one coating application device 13

which applies a coating material to one surface of the substrate 1 1 . In the

embodiment shown in Fig. 1 , a pair of coating application devices 13 are

provided, one to apply coating material to each respective side of the

substrate 1 1 . In practice, however, any number of coating application

devices 13 can be used as desired or as appropriate. Each coating application device 1 3 comprises a reservoir of coating

material 14, a take up roller 16 to take coating up from the reservoir 1 and

an application roller 17 to take coating from the take up roller 1 6 and apply

to the surface of a substrate 1 1 .

The reservoir 14 of coating material comprises an open topped

receptacle containing coating material.

The take up roller 16 comprises a rubber, steel or ceramic roller

mounted such that upon rotation its surface takes up coating from the

reservoir. Alternatively the take up roller 1 6 can be formed from any

suitable material, as desired, or as appropriate.

The application roller 17 also comprises a rubber, steel or ceramic

roller mounted in such a manner that its surface is in close proximity to both

a surface of the take up roller 16 and the surface of the substrate to which

the coating is to be applied.

In use, as substrate 1 1 is fed around the driven roller 12, each

application device 13 applies coating material to a respective surface of the

substrate 1 1 . To do this, the take up roller 16 is rotated such that its

circumferential surface 18 takes up coating material 19 from the reservoir

14 and transfers it to the surface 21 of the application roller 17. The

surface 21 of the application roller 17, when rotated, applies this coating

material to the surface of the substrate 1 1 .

In this conventional system, in order to control the thickness of

coating material applied to the substrate 1 1 , it is usual for there to be a gap (not shown in the drawing for the sake of clarity) between the surface 18

of the take up roller 16 and the surface 21 of the application roller 17. It

will be appreciated that the dimensions of this gap determines the thickness

of the layer of coating material eventually applied to the substrate 1 1 .

Therefore with this conventional system it is necessary for this gap to be

correctly set up prior to the apparatus being operated and for the gap to be

continuously monitored during operation to ensure that an accurate and

even application of coating material to the substrate 1 1 is achieved.

Furthermore due to the manner in which the take up roller 16 takes up

coating material from the open top reservoir 14 there is considerable scope

for wastage of coating material and it is not uncommon in these

arrangements for there to be a wastage of approximately 10 to 15% of the

coating material used.

Referring now to Fig. 2 there is shown one form of coating apparatus

30 according to the invention in which more accurate application of a

coating material to a substrate can be achieved with minimal or no wastage

of coating material.

In the apparatus of Fig. 2, similarly to the conventional apparatus, the

substrate 31 is fed around a driven roller 32 from a storage roll to a finished

roll. As the substrate 31 passes around the driven roller 32 it passes at

least one application device 33 which applies a coating material to one

surface of the substrate 31 . As with the conventional system of Fig. 1 ,

whilst in Fig. 2 a pair of application devices 33 are shown, each one of which applies a coating material to a respective surface of the substrate 31 ,

in practice any number of application devices 33 can be used as desired or

as appropriate.

The application device 33 as used in the apparatus of the invention

is considerably different from that used in the conventional apparatus. The

application device 33 comprises an enclosed reservoir 34 of coating

material, a take up roller 36 in close proximity to the reservoir 34 to take up

coating material from the reservoir 34 and an application roller 37 to take

up coating material from the take up roller 36 and transfer it to the

substrate 31 .

The enclosed reservoir 34 comprises a rear wall 36, top wall 37 and

bottom wall 38. A doctor blade 39 depends downwardly from the top wall

37 and another doctor blade 41 projects upwardly from the bottom wall 38,

both doctor blades 39,41 terminating at the surface of the take up roller 36

for a purpose to be described hereinafter.

The reservoir 34 has an open front part which in the apparatus of the

invention is closed off, to give an enclosed reservoir, by positioning of the

take up roller 36 such that at least a part of its surface 42 of the roller 36

extends into and closes off the open front part of the reservoir 34.

The take up roller 36 comprises an engraved roller having a

preselected engraved pattern engraved onto the surface thereof. This

pattern can be as few as 1 1 "cells" per linear inch and as many as 250

"cells" per linear inch engraved with the surface of the roller 36. The engraved pattern has a particular depth and size and is configured to give

a desired thickness and extent of coating to the substrate. The engraved

pattern can comprise a multiplicity of engraved "cells" of many different

configurations such as for example quadrangular or pyramid and can of any

desired density.

The application roller 37 is a rubber roller of the same type as used

in the conventional apparatus. Alternatively, as with the conventional

apparatus, the application roller can be formed with any suitable material,

as desired, or as appropriate.

In use, the engraved roller 36 rotates with its surface 42 in close

proximity to the open front of the reservoir 34. Coating material is applied

under pressure to the surface 42 of the roller 36 and enters the engraved

pattern. The doctor blades 39,41 wipe the surface of the engraved roller

36 as it rotates and therefore coating material is removed from the surface

of the roller 36 other than in the region of the engraved pattern. As the

engraved roller 36 continues to rotate the material within the engraved

pattern is transferred to the surface 43 of the application roller 37. Rotation

of the application roller 37 causes application of the coating to the

substrate.

It will be noted from Fig. 2 that there is a no gap between the surface

42 of the engraved roller 36 and the surface 43 of the application roller 37.

This arises due to the fact that all the coating material is confined within the

engraved pattern on the engraved roller 36 and the thickness of the coating eventually applied is dictated solely by the depth of the engraved pattern.

There is no coating on the surface 42 of the engraved roller 36 other than

in the engraved pattern. Therefore there is no need for a gap between the

engraved roller 36 and the application roller 37. The lack of a gap means

that the transfer of coating material from the engraved roller 36 to the

application roller 37 is accurate and reduces coating material wastage. It

also leads to the removal of the requirement for initial set up and continuous

monitoring of such a gap as is required in conventional apparatus.

Furthermore the application of coating material to the surface 42 of

the engraved roller 36 under pressure leads to a uniform and even

application of the material onto the engraved pattern of the roller 36. This

means that the pattern is completely filled with coating material as required

and results in a considerably more accurate application of material to the

substrate. Furthermore this means of application of coating material to the

engraved roller further reduces material wastage.

It is of course to be understood that the invention is not intended to

be restricted to the details of the above embodiments which are described

by way of example only.

Claims

CLA1MS

1 . A coating apparatus, particularly for coating a continuous roll of

sheet-like metallic substrate, said apparatus comprising an enclosed

reservoir containing coating material under pressure, an engraved

roller disposed in close proximity to said enclosed reservoir to take up

coating material therefrom and an application roller to take up coating

material from the engraved roller and apply the material to a surface

of a substrate.

2. A coating apparatus according to claim 1 , wherein one or more

doctor blades are provided which wipe the surface of the engraved

roller to remove coating from areas of the roller other than the

engraved pattern and ensure that a uniform depth of coating is

provided in the engraved pattern.

3. A coating apparatus according to claim 1 or claim 2, wherein the

reservoir is enclosed by rear, top and bottom walls of the reservoir

and at least a part of the surface of the engraved roller.

4. A coating apparatus according to claim 3, wherein the reservoir is

enclosed by rear, top and bottoms walls of the reservoir, at least a

part of the surface of the engraved roller and said one or more doctor

blades.

5. A coating apparatus according to claim 2, wherein a pair of doctor

blades are provided, one depending from a top wall of the reservoir

and the other extending upwardly from a bottom wall of the reservoir, both blades terminating adjacent the surface of the

engraved roller.

6. A method of applying a coating to a continuous roll of sheet-like

metallic material comprising applying coating material to a surface of

an engraved roller under pressure from an enclosed reservoir of

coating material, transferring the coating material from the engraved

roller to an application roller and applying the coating material from

the application roller to the substrate.

7. A method according to claim 6, wherein the substrate is provided in

the form of a continuous roll and is fed to the application roller, is

coated thereby and is then wound once again into a finished roll.