GB2093766A

GB2093766A - Improvements in roofing panels

Info

Publication number: GB2093766A
Application number: GB8131541A
Authority: GB
Original assignee: WEATHERSPAN Ltd
Current assignee: WEATHERSPAN Ltd
Priority date: 1981-02-24
Filing date: 1981-10-20
Publication date: 1982-09-08

Abstract

Chipboard panels (10) are fed through a coating station (16) in end- to-end or side-by-side abutting relationship. A web (91) is fed from a supply roll (42), disposed generally above the coating station (16), and around a sink roller (95) disposed in a heated vat (18) of molten bitumen. Bitumen is also fed from an outlet (49) of the vat (18) onto the panels (10) so as to form a bitumen puddle immediately upstream of the coating station (16) to which the bitumen- impregnated web is guided. A heated applicator roller (28) presses the web onto the panels (10). Sand is fed from a hopper (31) to the thus felted panels to prevent sticking. The reverse sides of the panels can be wax-coated. <IMAGE>

Description

SPECIFICATION Improvements in roofing panels The present invention relates to the manufacture of roofing panels and more particularly to a method and apparatus for coating board, such as chipboard, with bitumen and applying felt to the board.

There have been various proposals for applying bitumenised felt to chipboard in the manufacture of roofing panels. One way is to apply bitumen to the panels and then, while the bitumen is still molten, to bring a bitumenised felt into contact with the coated board and thereafter allowing bitumen to set. In theory there is no need to feed molten bitumen onto the boards; the bitumenised felt itself contains sufficient bitumen and, by heating the bitumen on the felt immediately before it is brought into contact with the board, a puddle of bitumen can be formed and can be maintained, sufficient for the purpose of bonding the felt to the board.

British Patent No. 1,524,734 describes a more sophisticated method and apparatus wherein chipboards are coated on one face with bitumen and a saturated felt is immediately thereafter applied to the board, the saturated felt being obtained by feeding a fibre mat through a hot impregnating vat containing bitumen. A disadvantage with this method and apparatus is that there are two vats, one for feeding the bitumen onto the boards and the other for dipping the felt. Furthermore the felt impregnated with the bitumen has to be handled between the dipping vat and the roller by which the felt is applied to the boards. The long run of hot impregnated felt is difficult to handle and forms a heat trap, making the working conditions for the personnel operating the apparatus very unpleasant.Furthermore the need to pass the hot impregnated felt over numerous guide rollers renders the apparatus prone to the development of faults.

A method of treating panels in accordance with the present invention comprises moving panels through a coating station, heating bitumen in a vat disposed adjacent the coating station, feeding molten bitumen from the vat to the coating station to form a puddle on the moving panels, feeding a web through the molten bitumen in the said vat and directly to the coating station and applying the dipped web to the panels at the coating station.

Thus, by means of the present invention, the felt is manufactured immediately before it is applied to the boards and there is no long run of impregnated felt to handle. Furthermore only one vat is needed.

Apparatus according to the invention for applying bitumenised felt to panels comprises means for moving the panels through a coating station, a vat disposed adjacent the surface of the panels to be coated upstream of the coating station, means for heating bitumen in the vat, means for supplying molten bitumen from the vat to said surface of the panels at the coating station to form a bitumen puddle on the panels, means for feeding a web through the vat and means for applying the dipped bitumen impregnated web to the panels at the coating station.

Whilst it is possible for the supply role for the web to be located at the upstream side of the vat, such an arrangement is not entirely satisfactory since fumes from the vat tend to become trapped beneath the web which is being fed to the vat.

Also several sink rolls must be provided for guiding the web through the vat unless the web is to overlie substantially the whole of the upper surface of the bitumen in the vat. Thus, it is preferable for the supply roll for the web to be located at the downstream side of the vat, for example generally above the coating station. In this way the web is fed into the vat at the same end as it is withdrawn, thereby leaving substantially the whole of the upper surface of the molten bitumen in the vat unobstructed whereby fumes from the vat can be readily removed and substantially the whole of the region of the vat can be ventilated to keep it cool and thereby more pleasant for the operating personnel.Only a single sink roll is provided for guiding the web within the vat but in those instances wherein it is desired for the web-to remain in the vat for a longer period, additional sink rolls can be provided, whilst retaining the entry and exit of the web at the same end of the vat.

Accordingly in accordance with a separate aspect of the present invention, a method of treating panels comprises moving panels through a coating station, heating bitumen in a vat disposed adjacent the coating station, feeding molten bitumen from the vat to the coating station to form a puddle on the moving panels, and feeding a continuous web from a supply roll disposed at the same end of the vat as the coating station to the panels at the coating station. Thus in accordance with this aspect of the present invention the front end of the vat and substantially the whole of its top are left unobstructed to improve ventilation around the vat and to facilitate the removal of fumes.

Whilst according to one embodiment of this aspect of the invention the web is a fibrous web which is fed into the vat at one end and is withdrawn from the vat at the same end before being applied to the panels, it is also possible for the web to be in the form of a felt which can then be fed directly from the supply roll to the coating station, without in any way obstructing the vat. A further advantage of this arrangement is that the run of felt from the supply roll to the coating station is very small and no guide rolls other than possibly a tension roll are required for the felt.

Apparatus according to another aspect of the invention for applying bitumenised felt to panels comprises means for moving the panels through a coating station, a vat disposed adjacent the surface of the panels to be coated upstream of the coating station, means for heating bitumen in the vat, means for supplying molten bitumen from the vat to said surface of the panels at the coating station to form a bitumen puddle on the panels, and means for supporting a supply roll of a web adjacent that end of the vat which is also adjacent the coating station, whereby the web can be fed directly from the supply roll to the coating station without passing substantially above the vat.

In one embodiment of this aspect of the invention a sink roll is provided for guiding the web into and out of the vat. In another embodiment of the invention the supply roll is a felt and is so supported that the felt does not pass into or above the vat.

The panels with which the present invention is concerned will usually be chipboard panels and such panels are normally supplied as rectangular panels measuring eight feet by four feet, that is to say, approximately 2.44 metres by 1.22 metres.

Generally the panels are fed through the apparatus in end-to-end relationship but according to yet another aspect of the present invention, a method of treating rectangular panels comprises moving the panels through a coating station in side-byside abutting relationship and feeding molten bitumen and a web or felt to the panel at the coating station, the width of the web or felt being commensurate with the length of the panels.

The panels with the felt thus applied to one side can be used as they are. However it is preferable, particularly in the case of chipboard, to render the other side of the panels waterproof. In accordance with one preferred embodiment of the invention the other sides of the panels are coated with wax.

To this end, the panels are turned over and then fed through a second coating station at which wax is poured onto the panels from a second vat and the panels are fed past a weighted roller which acts as a doctor to maintain a wax puddle at the respective coating station. Additional heat can be applied to the puddle for the purpose of ensuring that the wax soaks into the panel.

In an alternative embodiment, the panels are turned over and then fed again through the previously mentioned apparatus in order to apply bitumen and a second felt layer to the other side.

The invention is further described by way of example with reference to the drawings in which: Fig. 1 is a perspective view of apparatus in accordance with one embodiment of the invention for applying bitumenised felt to roofing panels such as chipboard panels, Fig. 2 is a somewhat diagrammatic perspective view of the vat for the bitumen in the apparatus of Fig. 1, Fig. 3 is a diagrammatic side elevation of further apparatus for applying a wax coating to the other side of the panels, Fig. 4 is a perspective view of a modification of the apparatus of Figure 1, Fig. 5 is a diagrammatic side elevation of a further modification of the apparatus of Fig. 1, and Fig. 6 is a similar diagrammatic side elevation but showing another embodiment of apparatus for applying bitumenised felt to roofing panels.

Fig. 1 shows chipboard panels 1 O-of roofing grade being successively fed from an input stack 11 to an output stack 12 along a substantially horizontal roller conveyor 13. At the input end the panels 10 are fed between a drive roller 14 and a pinch roller 1 5, e.g. manually, and thereafter the panels once in the nip push the preceding panels before them in end-to-end abutting relationship as shown; the panels being moved continuously by the roller conveyor. The conveyor 13 transports the panels substantially horizontally through a coating station 1 6 at which bitumen is applied to the upper face of the panels and an impregnated web is pressed onto the coated panels.

A vat 18 is supported above the conveyor 13 adjacent the upper surface of the panels at the upstream side of the coating station 1 6. The construction of the vat 1 8 will be described in more detail with reference to Fig. 2 but in Fig. it can be seen that molten bitumen from the vat is poured onto the panels through an outlet manifold 1 9 to form a bitumen puddle 20 at the coating station. A web 21 of the kind suitable for making roofing felt is drawn from a supply roll 22 whose means of support have been omitted from Fig. 1 of the drawings for the sake of clarity. The web 21 is passed through the vat 1 8 around guide rollers 23 and 26 and sink rollers 24 and 25 which are disposed within the vat. The vat contains submerged heaters for maintaining bitumen in the vat in a molten state.The vat is replenished from time to time in order to keep it full of molten bitumen.

The bitumen impregnated web 27 leaving the vat is guided around the guide roller 26 down to the coating station 1 6 at which a weighted applicator roller 28 is disposed. The means for supporting the applicator roller 28 are not shown in the drawing. The applicator roller 28 is vertically guided and is held down under gravity, additional weight being provided for this purpose if need be.

The roller 28 is water cooled, water supply and return pipes 29 for this purpose being shown diagrammatically. The water is passed through the interior to the roller 28 from end-to-end. It can be seen that the puddle 20 of bitumen is trapped in the nip between the boards and the impregnated web 27 and the weight of the applicator roller 28 is chosen so that excess bitumen is squeezed out of the nip. Trapping of the web in the nip of the roller 28 causes the web continuously to be withdrawn from the support roller through the vat onto the upper surface of the boards due to the continuous movement of the latter effected by the roller conveyor. Spring biassed fences 30 are provided at opposite sides of the panels 10 at the coating station 1 6 to prevent the bitumen spilling freely over the sides of the panels, whilst permitting some bitumen to be spread over the panel side edges. The continuous advance movement of the panels prevents the bitumen spreading from the puddle too far backwards.

A dusting hopper 31 is disposed above the impregnated web 27 in order to apply sand or other suitable aggregate to the upper surface of the web and thereby provide a suitable surface finish and prevent the roller 28 from sticking to the web. Small dusting hoppers 32 are disposed at the sides of the panels downstream of the coating station 1 6 for the purpose of coating any bitumen which oozes out from the sides. Finally the panels pass beneath a further dusting hopper 33 to ensure that sufficient dressing is on the coated faces of the panels to prevent the panels from sticking to one another in the stack 12.

Fig. 2 of the drawings shows the vat 1 8 in somewhat more detail. The vat contains two submerged gas burners 35 fed with gas through a conduit 36. The combustion gases are conducted through submerged heater tubes 37, preferably of square section as shown, and are conducted to flue outlets 38. It will be seen that each of the two burners 35 feeds a central limb 37a which in turn feeds two side limbs 37b which lead to the individual flues 38. The limbs 37a and 37b extend transversely across substantially the full width of the vat.

Fig. 2 also shows the outlet 39 which is controlled manually by meansof a valve 40 and which leads to the manifold 19 of Fig. 1.

Fig. 2 also shows the sink rollers 24 and 25.

The sink rollers are driven to the ends of pivoted arms 41 and 42, only the arms at the far side in Fig. 2 being shown (the arms of the near side have been omitted in order to reveal the details of the vat). The sink rollers 24 and 25 are shown in their elevated positions in which they are placed for the purpose of threading the web through the apparatus. Thus in their raised positions the sink rollers are clear of the molten bitumen. After the web has been threaded the sink rollers are lowered to their positions shown in Fig. 1 in order to immerse the web in the molten bitumen in the vat.

Whilst the panels in the stack 12 coated on one side with bitumenised felt may be considered as a finished product, it is preferable in the case of chipboard to render the other side of the panels waterproof. One way of doing this is to turn over the stack of panels 12 and feed them through a waxing device such as is shown in Fig. 3 of the drawings. It is conceivable to turn the panels over one at a time as they come off the feiting apparatus of Fig. 1 by means of a turnover device 45 and immediately feed the panels to the waxing device of Fig. 3. Alternatively, the panels need not run continuously from one apparatus to the other and instead the stack 1 2 of Fig. 1 can be inverted as such and placed at the input end of the waxing apparatus of Fig. 3.In either event the panels 50 are fed along a roller conveyor 53 from a turnover device 45 or from the input stack, through a waxing station 56 and to an output stack (not shown). Since the panels have been inverted the lower faces of the panels on the conveyor 53 are the faces which have been covered with a bitumenised felt. The panels are feld, e.g.

manually, between a drive roller 54 and a pinch roller 55 so that the panels push the preceding panels before them in end-to-end abutting relationship as shown. An applicator roller 68 is disposed at the waxing station 56 and is held down by gravity rather like the roller 28 of Fig. 1.

A wax puddle is maintained on the panels at the waxing station 56 immediately upstream of the applicator roller 68. Wax is fed to this puddle from a vat 58 which contains a single immersed gas burner. The vat 58 is thereby kept full of molten wax. The wax is fed from an outlet 69 to a manifold 49 which feeds the wax to the puddle. A valve 70 is used to manually control the wax flow to the puddle.

It is important that the wax should soak into the panels in order that it will not be simply removed when the panels rub against one another. To this end the panels themselves are heated by means of gas burners 65 which add heat to the puddle of molten wax and thereby promote heating of the panels themselves and the soaking of the wax into the panels. As in the apparatus of Fig. 1, side fences 60 press against the side edges of the panels to prevent the wax from flowing freely over the side edges. In practice some of the wax does flow over the side edges and serves to coat the side edges. Likewise some of the wax flows between the abutting edges of the panels and thereby also coats these edges. To collect any excess wax which may drip through, a collecting tray can be disposed beneath the waxing station 56 and the wax can be returned to the vat 58 from time to time.

Weighted doctor blades 51 can be arranged at 45 to the path of movement of the panels downstream of the waxing station 56 for brushing off surplus wax. Finally the wax face can be coated with fine sand or other suitable separating agent from a dusting hopper 63.

Instead of coating the reverse sides of the panels with wax, it is possible to coat them with bitumen e.g. by means of an apparatus similar to that of Fig. 3. Alternatively it is possible to coat them with felt. This can simply be achieved by taking the stack 12 of Fig. 1, inverting the stack and then putting the panels through the same apparatus again but the other way up.

In order to improve the appearance of the panels and possibly in order to help to coat the panel edges, the panel edges can be sprayed with a bitumen solution e.g. in the stack 11 of Fig. 1.

The subsequent coating steps ensure that adequate bitumen or wax impregnates the edges of the panels.

In the modification shown in Figure 4, cooling of the roller 28 is omitted and consequently the roller is heated by the freshly bitumenised web 21.

In practice, on start-up of the apparatus, the roller 28 is heated by any convenient means, e.g. gas burners, to a temperature such as to maintain any bitumen adhering thereto from the web in a molten condition. Although on start up, the rollers acquires a coating of bitumen from the dipped web, the coating once formed, does not accumulate any further bitumen from the web due to its molten condition. Subsequently, the coating is maintained in a molten condition on at least its external surface in contact with the web, by heat from the web. The use of the "hot" roller therefore has the advantage that, following start up, there is no removal of bitumen from the dipped web.

Consequently, the sand may be, and preferably is, applied to the web downstream of the roller 28 as indicated in Figure 4 by the positioning of the sand hopper 31 downstream of the roller 28.

Figure 4 also shows an auxiliary or pre-melt vat 101 to melt down bitumen feedstock before it enters the vat 18; and this pre-melt vat may also be used in the Figure 1 embodiment. The pre-melt vat as shown in Figure 4, is positioned adjacent the lateral side of vat 1 8 bearing the sink rollers.

The vat contains a gas burner (not shown) of a similar kind to those used in vat 18 housed again in a square-section tube 105 communicating with a further similar tube 107 serving as a gas flue in a like manner to the arrangement used in vat 1 8.

The pre-melt vat has an upper wall 111 bearing an aperture around which is mounted an entry chest 113 formed with a lid 11 5. The vat also provides a "drawer" 117 to close the aperture of wall 111 of the vat. In use, pieces of solid bitumen are entered into the chest with the drawer in the closed position, the lid of the chest is then closed and the drawer opened to allow the pieces of bitumen to fall into the vat. Entering the bitumen in this way avoids splashing of the molten bitumen from the vat to the exterior thereof.

The vat 18 is modified by having a port formed therein and covered by a grille 121, and the premelt vat is formed with a complementary aperture 123; the respective side walls of the two vats being secured together to prevent escape of molten bitumen as it passes from the pre-melt vat to vat 1 8 via the grille; the grille being provided to prevent solid lumps of bitumen passing into vat 18.

By use of the pre-melt vat, the feedstock capacity, of the apparatus can be increased to match the production rates that can be achieved with the apparatus, but without requiring any change in the capacity of vat 18, and it also permits a constant level of feedstock to be maintained in vat 1 8. Further, since no solid bitumen is fed to vat 1 8, the risk of damage to the web by solid pieces of bitumen is avoided. This is of especial importance where the web is formed of a rag based paper since such a web is easily damaged.

Fig. 5 of the drawings shows another modification in which the supply roll 92 of the web 91 is diposed at the downstream side of the vat 18. Thus the web 91 is fed from the roll 92, beneath a tensioning roller 93, over a guide roll 94 disposed adjacent the downstream side of the vat 18, down into the vat and around a sink roller 95, up through the vat to a guide roll 96 disposed close to the guide roller 94, and then to the applicator roller 28 at the coating station 1 6. The apparatus of Fig. 5 is otherwise similar to that of Fig. 1 and like parts are denoted by like reference numerals. If the sand hopper 31 cannot be arranged sufficiently close to the coating station, the hopper can discharge under an inclined guide plate 94 so that the sand or other dusting powder can be deposited onto the coated boards close to the applicator roller 28.

Fig. 6 of the drawings shows an apparatus which can be used for the conventional coating process in which a felt 91 a is fed from a supply roll 92 over a guide roll 94a directly to the applicator roller 28. Because a felt is used rather than a web, the felt is not passed through the vat 18 but directly to the puddle to molten bitumen formed on the panels 10 at the coating station 1 6 by the discharge of molten bitumen through an outlet 49 from the vat 18. The embodiment of Fig. 6 is otherwise similar to the preceding embodiments.

The embodiment of Fig. 6 illustrates that, by arranging the felt supply roll 92 adjacent the downstream side of the vat 1 8 the felt does not pass above or close to the vat so that the whole region around the vat can be adequately ventilated to improve the working environment for the operators of the apparatus.

Whilst the drawings illustrate the chipboard panels being passed through the apparatus in endto-end abutting relationship, if the apparatus is made wider, the rectangular panels can be passed through the apparatus in side-by-side abutting relationship, thereby increasing the rate of production. It is necessary in this case however for the web or felt to have a width corresponding to the length of the panels.

Claims

1. A method of treating panels, comprising moving panels through a coating station, heating bitumen in a vat disposed adjacent the coating station, feeding molten bitumen from the vat to the coating station to form a puddle on the moving panels, feeding a web through the molten bitumen in the said vat and directly to the coating station, and applying the dipped web to the panels at the coating station.

2. A method as claimed in claim 1, in which the vat is replenished by supplying bitumen in solid form to the vat and melting the bitumen in the vat.

3. A method as claimed in claim 1, in which the vat is replenished by supplying molten bitumen to the vat.

4. A method as claimed in claim 1,2 or 3, in which the web is fed from a supply roll disposed at the upstream side of the vat.

5. A method as claimed in claim 1,2 or 3, in which the web is fed from a supply roll disposed at the same end of the vat as the coating station.

6. A method of treating panels comprising moving panels through a coating station, heating bitumen in a vat disposed adjacent the coating station, feeding molten bitumen from the vat to the coating station to form a puddle on the moving panels, and feeding a continuous web from a supply roll disposed at the same end of the vat as the coating station to the panels at the coating station.

7. A method as claimed in claim 6, in which the web is a fibrous web which is fed into the vat at one end and is withdrawn from the vat at the same end before being applied to the panels.

8. A modification to the method claimed in claim 6, in which the web is in the form of a felt which is fed directly from the supply roll to the coating station.

9. A method as claimed in any of claims 1 to 8, in which the panels are rectangular and are moved through the coating station in end-to-end abutting relationship.

10. A method as claimed in any of claims 1 to 8, in which the panels are rectangular and are moved through the coating station in side-by-side abutting relationship.

11. A method of treating rectangular panels comprising moving the panels through a coating station in side-by-side abutting relationship, and feeding molten bitumen and a web or felt to the panel at the coating station, the width of the web or felt being commensurate with the length of the panels.

12. A method as claimed in any preceding claim, in which the panels are chipboard panels.

13. A method as claimed in any of claims 1 to 12, in which the other sides of the panels are coated with wax.

14. A method as claimed in claim 13, in which the panels are turned over and then fed through a second coating station at which wax is poured onto the panels from a second vat and the panels are fed past a weighted roller whjch acts as a doctor to maintain a wax puddle at the respective coating station.

1 5. A method as claimed in claim 14, in which additional heat is supplied to the puddle for the purpose of ensuring that the wax soaks into the panel.

16. A method as claimed in any of claims 1 to 12, in which the panels are turned over and then passed again through the previously mentioned coating station in order to apply bitumen and a second felt layer to the other side.

1 7. A method of treating panels, substantially as herein described, with reference to the drawings.

1 8. Apparatus for applying bitumenised felt to panels, comprising means for moving the panels through a coating station, a vat disposed adjacent the surface of the panels to be coated upstream of the coating station, means for heating bitumen in the vat, means for supplying molten bitumen from the vat to said surface of the panels at the coating station to form a bitumen puddle on the panels, means for feeding a web through the vat, and means for applying the dipped bitumenimpregnated web to the panels at the coating station.

19. Apparatus as claimed in claim 18, in which web-feeding means includes at least one sink roller disposed in the bath for guiding the web through the molten bitumen in the vat.

20. Apparatus as claimed in claim 19, in which the or each sink roller is displaceably supported for movement to a temporary position outside the vat to facilitate threading of the web.

21. Apparatus as claimed in any of claims 18 to 20, in which the bitumen heating means comprises at least one submerged heater in the vat.

22. Apparatus as claimed in any of claims 18 to 21, in which the bitumen heating means comprises at least one gas-fired heater.

23. Apparatus as claimed in any of claims 1 8 to 22, which further comprises an auxiliary pre-melt vat for melting down replenishment bitumen prior to feed to the first-mentioned vat.

24. Apparatus as claimed in any of claims 1 8 to 23, in which the web-applying means comprises a cooled applicator roller for pressing the impregnated web onto the panels, means being provided for applying a dusting material to the impregnated web surface remote from the panels being provided upstream of the coating station to prevent the web from sticking to the applicator roller.

25. Apparatus as claimed in any of claims 1 8 to 23, in which the web-applying means comprises an un-cooled applicator roller for pressing the impregnated web onto the panels.

26. Apparatus as claimed in any of claims 18 to 25, in which a supply roll for the web is located at the upstream side of the vat.

27. Apparatus as claimed in any of claims 1 8 to 25, in which a supply roll for the web is located at the downstream side of the vat.

28. Apparatus for applying bitumenised felt to panels, comprising means for moving the panels through a coating station, a vat disposed adjacent the surface of the panels to be coated upstream of the coating station, means for heating bitumen in the vat, means for supplying molten bitumen from the vat to said surface of the panels at the coating station to form a bitumen puddle on the panels, and means for supporting a supply roll of a web adjacent that end of the vat which is also adjacent the coating station, whereby the web can be fed directly from the supply roll to the coating station without passing substantially above the vat.

29. Apparatus as claimed in claim 28, in which a sink roll is provided for guiding the web into and out of the vat.

30. Apparatus as claimed in claim 28, in which the supply roll is a felt and is so supported that the felt does not pass into or above the vat.

31. Apparatus as claimed in any of claims 27 to 30, in which the web supply roll is located generally above the coating station.

32. Apparatus for applying bitumenised felt to panels, constructed and adapted to operate substantially as herein described with reference to and as illustrated in the drawings.