GB1604046A

GB1604046A - Selective coating of steel strip

Info

Publication number: GB1604046A
Application number: GB24743/77A
Authority: GB
Original assignee: British Steel Corp
Current assignee: British Steel Corp
Priority date: 1977-06-14
Filing date: 1977-06-14
Publication date: 1981-12-02
Also published as: SE7806819L; AU3704478A; BE868085R; DE2825869A1

Description

(54) SELECTIVE COATING OF STEEL STRIP (71) We, BRITISH STEEL CORPORATION, a Corporation incorporated and existing under the Iron and Steel Act 1967 whose principal office is at 33 Grosvenor Place, London, S.W.1 do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to the production of coated strip and is concerned with the production of strip in which the coating is continuously applied to selected regions only.

The present invention is particularly, though not exclusively concerned with the production of steel strip provided with a coating of adhesive which is effective to bond an outer layer of plastics material optionally having a decorative finish or pattern. In one conventional process for producing such a coated product, moving steel strip is adhesively treated and is subsequently presented with a similarly moving film of plastics material which is then bonded to its steel substrate by, for example pressure applied at the nip between two rolls.

The adhesive, or any other coating material, is in general applied by way of roller coating or other suitable means in an arrangement which is capable of coating strip of different widths. In most cases this can be achieved only by coating the whole of and beyond the width of all but strip of the greatest width the arrangement can accommodate.

In the case where the coating is to be selectively applied, for example must terminate short of the strip edge, an unwanted border of coating will accordingly nonetheless remain, and it is an object of the present invention to produce a method for the selective continuous coating of strip material.

According to the broadest aspect of the present invention, apparatus for applying a surface coating to moving strip comprises an arrangement for transferring fluid coating material from a source to the strip surface together with control means which are responsive to the position of a strip edge and which are effective to prevent coating material from the source reaching a selected region of the strip required to remain uncoated, whereby the width of the uncoated region and its position relative to the edge remains substantially constant irrespective of lateral strip movement.

In a preferred embodiment of the invention the control means are effective to prevent coating material reaching a region of the strip lying adjacent an edge.

The coating arrangement may comprise spraying or roller coating. In the case of spraying a masking member spatially interposed between the source and the surface of the strip may be provided to prevent the incidence thereon of coating material.

In the case of roller coating, the coating may be prevented by the provision of a mechanism arranged to continuously remove coating material from that region of the applicator roll which is contiguous with the region of strip selected to remain uncoated.

Suitably the coating material is removed by blades which engage the applicator roll and are effective continuously to scrape off coating material transferred from the source.

Preferably the blades are secured to one end of a pivoted lever which carries at its other end a shoe arranged to engage the edge of the strip so that the blades move in unison with any lateral movement of the strip.

The apparatus of the invention may be used to produce strip in which a region adjacent each of the edges remains uncoated.

In this case the coating prevention means are provided adjacent each of the strip edges and in one embodiment are both arranged to respond to the position of one edge only, for example by being mechanically coupled to one another. Alternatively each of these means may operate separately of one another by being independently responsive to the position of the adjacent strip edge.

An embodiment of the invention will now be particularly described by way of example with reference to the accompanying drawing in which Figure 1 is a schematic side view of an adhesive coating station in a line for the continuous production of plastics coated steel strip and Figure 2 an end-on view of parts of the station illustrated in Figure 1.

Referring to the drawings, Figure I illustrates a station at which a layer of a suitable adhesive material is applied to one surface of steel strip 2 which at a subsequent station is coated with a film of plastics material in the manner disclosed and claimed in our Patent No. 1 550 817.

The plastics film is, in this embodiment of the invention, to be applied so as to terminate short of each of the edges of the strip 2 so as to leave adjacent each edge a border region which can be easily welded without further cleaning or other preparation. In most cases this requires the adhesive underlying the plastics film also to terminate short of each strip edge. Ideally, the line at which the adhesive terminates should be coincident with the edge of the applied plastics film and this coincidence should be maintained irrespective of any lateral drift or wander of the strip itself.

This may be achieved by the arrangement shown in Figure 1 in which the adhesive is applied by a roller coating technique from a source bath 4. Coating material is transferred to the strip 2 tensioned over roll 6 by way of a pickup roll 8 and a continuous applicator roll 10 supported for retention on framework 12.

Also moulted upon the framework is a tubular guide 14 of circular section which extends across the width of the strip 2 and which supports two laterally movable carriages 16and gru Carriages 16 and 18, which can freely slide along the guide 14, carry adjustable blades 20 and 22 whose free ends are biased agaaast and engage the surface of the applicator roll IQ.

Carria 16 and 18 are coupled by a tensioned flexible wire 24 which at one end is connected to a pivoted lever arm 26 by way of pulleys 28, 30 and 32. As shown in Figure 2, arm 26 also carries a shoe 34 which slideably engages one edge of the strip 2 downstream of the applicator roll 10. In this embodiment shoe 34 is gravitationally biased against the edge of the strip by way of a weight 36 which operates on carriages 16 and 13 by way of a continuation of wire 24 extenig over pulley 38. Weight 36 which also telissons the wire 24 moves in a guide 40 to constrain lateral movement.

In use af the apparatus of the invention, adhesive in the process of being transferred to strip 2 from source 4 will initially form a coating on applicator roll 10 but will he removed from selected regions by blades 20 and 22 before reaching the strip 2. Strip 2 will accordingly receive a coating only from those regions of the applicator roll 10 on which blades 20 and 22 do not operate.

Blades 20 and 22 are adjusted by way of the screw/slot combination shown to ensure that the regions of the strip 2 remain uncoated to the required width. Since blades 20 and 22 move in response to the lateral position of the strip over the tensioning roll 6, the uncoated regions will remain in the same relative position notwithstanding lateral wander. Since the width of the blades remains constant both the width and the position of the uncoated region of the strip 2 accordingly also remain constant.

It will be appreciated that while two blades have been shown to prevent coating on edge regions of the strip 2, one or more blades may be used to prevent a coating being applied to other regions of the strip 2. It will also be appreciated that while the blades are shown as being mechanically coupled to the shoe which is responsive to the position of the strip edge, other methods of coupling, for example pneumatic, hydraulic, or electric coupling may be employed.

It will also be appreciated that while the invention has been described with reference to the coating of strip with an adhesive as an intermediate step in a process for producing plastics coated steel strip, it may equally be applied to the selective coating of any metal or non-metal strip by other materials, for example paint or size. The invention may for example be applied to the continuous coating of metal strip with liquid systems such as alkyds, epoxys, acry licks, polyestcr and vinyls. In the case where a roller coating technique is employed, the the roller contiguous with the strip may be arranged to move in the same direction as the strip at the point of contact or in the reverse direction depending upon the nature of the coating material and the substrate.

WHAT WE CLAIM IS: 1. Apparatus for applying a surface coating to moving strip comprising an arrangement for transferring fluid coating material from a source to the strip surface together with control means which are responsive to the position of a strip edge and which are effective to prevent coating material from the source reaching a selected region of the strip required to remain uncoated, whereby the width of the uncoated region and its position relative to the edge remains substantially constant irrespective of lateral strip movement.

2. Apparatus as claimed in Claim 1 wherein the control means are effective to prevent coating material reaching a region of tile strip lying adjacent an edge.

3. Apparatus as claimed in Claim 1 or Claim 2 wherein the coating arrangement comprises a sprayer.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Figure 1 is a schematic side view of an adhesive coating station in a line for the continuous production of plastics coated steel strip and Figure 2 an end-on view of parts of the station illustrated in Figure 1. Referring to the drawings, Figure I illustrates a station at which a layer of a suitable adhesive material is applied to one surface of steel strip 2 which at a subsequent station is coated with a film of plastics material in the manner disclosed and claimed in our Patent No. 1 550 817. The plastics film is, in this embodiment of the invention, to be applied so as to terminate short of each of the edges of the strip 2 so as to leave adjacent each edge a border region which can be easily welded without further cleaning or other preparation. In most cases this requires the adhesive underlying the plastics film also to terminate short of each strip edge. Ideally, the line at which the adhesive terminates should be coincident with the edge of the applied plastics film and this coincidence should be maintained irrespective of any lateral drift or wander of the strip itself. This may be achieved by the arrangement shown in Figure 1 in which the adhesive is applied by a roller coating technique from a source bath 4. Coating material is transferred to the strip 2 tensioned over roll 6 by way of a pickup roll 8 and a continuous applicator roll 10 supported for retention on framework 12. Also moulted upon the framework is a tubular guide 14 of circular section which extends across the width of the strip 2 and which supports two laterally movable carriages 16and gru Carriages 16 and 18, which can freely slide along the guide 14, carry adjustable blades 20 and 22 whose free ends are biased agaaast and engage the surface of the applicator roll IQ. Carria 16 and 18 are coupled by a tensioned flexible wire 24 which at one end is connected to a pivoted lever arm 26 by way of pulleys 28, 30 and 32. As shown in Figure 2, arm 26 also carries a shoe 34 which slideably engages one edge of the strip 2 downstream of the applicator roll 10. In this embodiment shoe 34 is gravitationally biased against the edge of the strip by way of a weight 36 which operates on carriages 16 and 13 by way of a continuation of wire 24 extenig over pulley 38. Weight 36 which also telissons the wire 24 moves in a guide 40 to constrain lateral movement. In use af the apparatus of the invention, adhesive in the process of being transferred to strip 2 from source 4 will initially form a coating on applicator roll 10 but will he removed from selected regions by blades 20 and 22 before reaching the strip 2. Strip 2 will accordingly receive a coating only from those regions of the applicator roll 10 on which blades 20 and 22 do not operate. Blades 20 and 22 are adjusted by way of the screw/slot combination shown to ensure that the regions of the strip 2 remain uncoated to the required width. Since blades 20 and 22 move in response to the lateral position of the strip over the tensioning roll 6, the uncoated regions will remain in the same relative position notwithstanding lateral wander. Since the width of the blades remains constant both the width and the position of the uncoated region of the strip 2 accordingly also remain constant. It will be appreciated that while two blades have been shown to prevent coating on edge regions of the strip 2, one or more blades may be used to prevent a coating being applied to other regions of the strip 2. It will also be appreciated that while the blades are shown as being mechanically coupled to the shoe which is responsive to the position of the strip edge, other methods of coupling, for example pneumatic, hydraulic, or electric coupling may be employed. It will also be appreciated that while the invention has been described with reference to the coating of strip with an adhesive as an intermediate step in a process for producing plastics coated steel strip, it may equally be applied to the selective coating of any metal or non-metal strip by other materials, for example paint or size. The invention may for example be applied to the continuous coating of metal strip with liquid systems such as alkyds, epoxys, acry licks, polyestcr and vinyls. In the case where a roller coating technique is employed, the the roller contiguous with the strip may be arranged to move in the same direction as the strip at the point of contact or in the reverse direction depending upon the nature of the coating material and the substrate. WHAT WE CLAIM IS:

1. Apparatus for applying a surface coating to moving strip comprising an arrangement for transferring fluid coating material from a source to the strip surface together with control means which are responsive to the position of a strip edge and which are effective to prevent coating material from the source reaching a selected region of the strip required to remain uncoated, whereby the width of the uncoated region and its position relative to the edge remains substantially constant irrespective of lateral strip movement.

4. Apparatus as claimed in Claim 3

wherein the control means comprises a masking member interposed between the spray source and the strip surface.

5. Apparatus as claimed in Claim 1 or Claim 2 wherein the coating arrangement comprises a roller coater.

6. Apparatus as claimed in Claim 5 wherein the control means incorporates a member effective to remove coating material from the selected region of a roll which corresponds to the region of the strip to remain uncoated.

7. Apparatus as claimed in Claim 6 wherein the member operates on the applicator roll.

8. Apparatus as claimed in Claim 6 or Claim 7 wherein the member comprises a blade engaging the roll.

9. Apparatus as claimed in any preceding Claim wherein the control means are secured to a pivoted lever engaging an edge of the strip.

10. Apparatus as claimed in any one of Claims 1 to 8 wherein the control means are slidably carried on a support extending across the width of the strip.

11. Apparatus as claimed in Claim 10 Claim 10 wherein the control means are connected by way of a tensioned filament to a shoe engaging the strip edge.

12. Apparatus as claimed in any one of Claims 1 to 8 wherein the control means respond to the strip edge by electrical, pneumatic or hydraulic means.

13. Apparatus for applying a surface coating to moving strip substantially as hereinbefore described with reference to the accompanying drawings.

14. Apparatus for applying a surface coating to moving strip substantially as shown in and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.