FR2636357A1 - Process and apparatus for the continuous coating of webs of great lengths - Google Patents

Abstract

The invention relates to a process for coating a web of great length in a coating machine and to an apparatus for carrying out this process. The process is characterised in that an endless loop is formed with the web to be coated by joining its two ends to one another, and in that the loop thus formed is passed continuously through the coating machine. The invention is used for the multi-layer coating of fabric webs of great length.

Description

 The present invention relates to a method for coating a strip, in particular of fabric, of great length in a loom to be coated, as well as a device for implementing this method.

 It is known that, in the looms to be coated, a strip of fabric of great length successively passes through a coating station, or it is coated, on one side or on both, with a coating which is for example a solution of rubber in a suitable solvent, and a tunnel oven or coating is dried. At the end of the loom, the coated strip is wound on a take-up reel, most often with the interposition of an intermediate strip between its turns, in order to prevent them from adhering to each other.

 Each strip generally passes several times through the stirrup, in order to coat it with a plurality of layers, the number of these possibly being for example between 4 and 20. For each pass, the machine must be interrupted and the coated spool must be resumed. to bring it back in tette of the trade, which represents each time a significant loss of time, since of the order of 15 to 20 minutes, and a considerable expense in dividers.

 The object of the present invention is therefore to overcome these drawbacks and to propose a coating process of the kind specified above which, compared with known processes, provides a significant gain in productivity and significantly reduces the consumption of dividers.

 According to the invention, this object, as well as others which will appear subsequently, such as the production of a coated strip whose surface condition is improved, are achieved by a process of the kind specified above which is -characterized by the fact that an endless loop is formed with the strip to be coated by joining together its two ends, and that the loop thus formed is passed continuously through the loom to be coated.

 We understand that, thanks to the fact that the fabric is in the form of an endless loop, the coating is carried out continuously, and it is possible to apply as many layers as desired without it being necessary, for each pass, to wind the coated strip on a reel with the interposition of an interlayer, to stop the machine, and to bring the full reel back to the loom to make it undergo a new coating.

 It is clear that this results in a considerable saving of time, and that the use of dividers is no longer necessary only once for each coil, whereas it was once by coating pass, which translates into significant savings.

 It also results from this that it is then possible without problem to increase the number of layers, by giving them a smaller thickness, since this does not lead to a prohibitive increase in the duration of the treatment. The advantage is that the thin layers contain less solvent per unit area, and therefore produce fewer bubbles or craters, so that a much higher surface quality is obtained.

 In order to be able to easily treat strips of very different lengths, it is advantageous to have a strip of variable capacity pass through the strip to be treated which, moreover, absorbs variations in length which may occur during treatment. In addition, the numerous rollers of such a variable capacity reserve produce a calendering effect on the strip after each coating pass, which improves its surface condition.

 To form a new endless strip of fabric to be coated in the process according to the invention, the procedure is advantageously as follows: the endless strip of coated fabric is cut in place in the loom, its rear end is connected, in the direction of its travel, at the front end of the blank strip, the single strip thus formed continues to run through the loom by winding the strip of coated fabric on the output roll on a take-up spool until all its length has passed through the loom, the coated strip is separated from the virgin strip, and the latter is closed on itself by connecting its two ends together.

 This procedure is simple and quick, the ends of the strips preferably being connected to each other by welding or by gluing. In addition, the coated strip can be wound without difficulty on its take-up reel with the interposition of an intermediate strip between its various turns.

 The invention also relates to a device for implementing the process specified above, which is characterized in that it successively comprises a coating station, a tunnel oven, a reserve with variable capacity, and rollers return to return the strip being processed to its starting point upstream of the coating station.

 In the variable capacity reserve, the strip passes successively over a series of upper and lower rollers, the latter producing the calendering effect which was mentioned above and which improves the surface condition of the final strip.

 The device according to the invention is advantageously equipped with a welding or bonding station upstream from its coating station, which preferably includes two parallel lower rollers with fixed transverse axes which are located above the strip during processing, an upper roller which is parallel to the first two, which is located between them in the longitudinal direction and which passes under the strip, means for moving up the lower roller from its normal position where it is substantially below said upper rollers, and vice versa, and a welding or bonding device arranged transversely with respect to the strip, between the lower rollers and the upper roller when the latter is in the high position.

 To replace a coated and finished strip with a blank strip, it suffices to cut the latter, to connect its rear end, in the direction of travel, to the front end of the blank strip, by means of the welding device or seam specified above, to drive through the loom the blank strip by means of the coated strip which is connected to it, and to separate the two strips when their junction point has arrived at the welding or sewing station, the coated tape having been wound on a take-up reel as it left the loom. I1 then only have to close on itself the blank strip by gluing or welding so that it can be treated in turn.

 To facilitate these operations, the device advantageously comprises locking clamps for clamping the strips against the lower rollers specified above, as well as means arranged in the vicinity of the welding or sewing station to receive at least one supply reel, at least one take-up reel and / or at least one interlayer reel.

- The description which follows, and which has no limiting character, will make it possible to understand clearly how the present invention can be put into practice. It should be read against the accompanying drawings, among which:
- Figure 1 shows a side view of the loom to be coated according to the invention; and
- Figures 2A to 2D show, in a highly schematic way, the welding or sewing station of the installation of Figure 1 in four successive stages of its operation.

 The loom of FIG. 1 comprises, in a conventional manner, a 1 hour single or double-sided coating station of known type, then a tunnel oven 2, the assembly being crossed in the direction of arrow F by a strip of fabric 3 of great length.

 Here, however, and according to the invention, the strip 3 is in the form of an endless loop which is produced by closing it on itself by sewing or welding, for example.

 On leaving the oven 2, and also according to the invention. the strip 3 enters a reserve with variable capacity which is designated as a whole by the reference 4, which includes a large number of upper rollers 5 and lower rollers 6 and 6 ′, and in which the strip 3 alternates in laces on an upper roller 5 and under a lower roller 6 or 6 '.

 The axes of all the upper rollers 5 are transverse, mutually parallel and located in the same horizontal plane. It is the same for the lower rollers 6 which are located on the inlet side, but the lower rollers 6 'which are located downstream, therefore on the outlet side, are not with fixed axes like the previous ones.

Indeed, they are simply guided at their ends in vertical slides shown schematically in 7, so that they are free to go up and down under the effect of their own weight, to which is possibly added the action of springs that pull them down.

 All these rollers 6 ′ are identical to each other, as are their possible springs, and they are therefore subjected to the same vertical force directed downwards, and, in practice, they all come to be placed substantially in the same horizontal plane whose the height depends on the length of the strip 3 in the reserve 4, which allows the latter to easily absorb significant variations in length of the strip 3.

 It should also be noted that the rollers 5, 6 and 6 ', thanks to their large number, play the role of calendering rollers for the coated fabric and smooth the latter, which improves its surface condition.

 Also according to the invention, the strip 3, after leaving this reserve 4, passes over a transverse deflection roller 8 which is arranged above the reserve in question and which deflects the strip towards the head of the loom. Then, it passes alternately below and above transverse rollers 9 spaced along the installation, in the direction of arrow F ', then, at the front of the loom, on two other deflection rollers 10 and 11 which are arranged in the same vertical plane in front of the loom and which bring it back to the coating station 1 through a sewing or welding station 12.

In the installation which has just been described, the fabric circulates in the form of a loop 3 of 200 to 300 m or more, and it is possible to apply to it continuously a large number of coating layers, without '' it may be necessary to stop the machine every time. We understand that this results in a considerable gain in productivity, and, on the other
Wax, it becomes possible to multiply the layers without the duration of the operation being prohibitive, which allows to apply each time very thin layers, with the advantage that one uses less solvent and qie this avoids the appearance of bubbles or craters, which therefore obviously leads to a much higher surface quality.

 It should be noted here that this installation can result from the simple transformation of an existing coating loom of the conventional type, by the simple and relatively inexpensive addition of the reserve 4 & variable capacity and of a few deflection rollers 8 at 11.

 The welding or sewing station 12 is used to connect the two ends of a long strip of fabric together to transform it into a continuous loop. Its operation will now be described with reference to FIGS. 2 A to 2D.

 In these figures 2, we find the oven 2 and the strip 3, but the latter passes here under the oven 2 to reach the head of the loom after leaving the variable capacity reserve 4 and, therefore, it meets the roller 11 from below, no longer from above.

 FIG. 2A represents the welding or sewing station 12 in its starting position where the coating of the strip 3 is finished and where it is therefore a question of winding the latter on a take-up reel 20 and replacing it with a blank strip which must also be shaped into an endless loop.

 After passing over the deflection roller 11, the strip 3 which moves in the direction of the arrows passes under two upper transverse rollers 24 with fixed axes spaced from one another and, between these two upper rollers 24 and at mid -distance from these, on a lower transverse roller 25 which can be moved upwards in a plane -Wortical and brought back to its initial position of FIG. 2A.

 The grippers 26 allow the band 3 to be clamped on the corresponding roller 5urarieur 24; they are open in the starting position of FIG. 2A.

 Pinn understood, the strip 3 comprises a seam or a weld 22 which has Fermis to close it on itself when it is put in place in the trade. We start by stopping the latter so that this seal 22 is at the start of the oven e, which allows the last few meters of the strip to dry, then the strip 3 is made to move backwards, and therefore in the opposite direction. arrows F, until the seal 22 is in the vicinity of the welding or sewing station 12.

 As can be seen in FIG. 2B, the one of the tongs 26 which is closest to the oven 2 is then tightened on the corresponding lower roller 24, which blocks the strip 3 at this location, and the lower roller 25 is lifted 1usqu ' above a welding or sewing device 23, so that the strip 3 takes the form of a peak, and that the seal 22 is at the height of the connection device 23. The cut is then strip 3 at the seam or weld 22.

 In the next phase shown in FIG. 2C, the rear end of the strip 3 is connected to the front end of a new strip 3 'which is wound on a delivery reel 27, this junction taking place by means of the welding or sewing apparatus 23. The loom is restarted and the new strip 3 ′ of the supply reel 27 is driven into the loom by the coated strip 3, as indicated in 29 in dashed lines, the interlayer possibly present between the turns being wound on a take-up reel 28. Simultaneously, the coated strip is wound on the take-up reel 20, an interlayer coming from a supply reel 21 being interposed between its turns, if necessary.

 When all of the coated strip 3 is wound on the reel 21, all of the blank strip 3 ′ is in the installation and its possible interlayer is on the reel 28. Then its running is stopped and it is sewn or welded by means of the device 23, as shown in Figure 2D, the two clamps 26 being clamped and the lower roller 25 being lowered, at least partially.

 It then suffices to loosen the clamps 26 and completely lower the lower roller 25 to return to the starting stage of FIG. 2A, the small loop which is found in FIG. 4D being, of course, absorbed thanks to the reserve with variable capacity 4 of FIG. 1.

 Finally, it should be noted that the method according to the present invention can be improved by using two of the coating looms which have just been described, which halves the execution time.

 The reserve with variable capacity is then located after the two looms if we want to make two plasters on the same face, and between the two looms if we want to make a plaster on the two opposite faces of the bandaged.

Claims (10)

- CLAIMS 1. Method for coating a very long strip in a coating loom, characterized in that an endless loop is formed with the strip to be coated by joining together its two ends, and that the the loop thus formed is passed continuously through the loom to be coated. 2. Method according to claim 1, characterized in that said band is made to cross a reserve with variable capacity. 3. Method according to any one of claims 1 and 2, characterized in that, to form a new endless strip of fabric to be coated, the endless strip of coated fabric is cut in place in the loom, its rear end, in the direction of its travel, at the front end of the blank strip, the single strip thus formed continues to run in the loom by winding at the exit the strip of coated fabric on a take-up reel until that its entire length has passed through the loom, the coated strip is separated from the virgin strip, and the latter is closed on itself by connecting its two ends together. 4. Method according to any one of claims 1 to 3, characterized in that the ends of the strips are connected together by welding or by bonding. 5. Method according to any one of claims 3 and 4, characterized in that one passes the coated strip, after its exit from the tunnel oven, on a plurality of rollers having a calendering effect. 6. Device for implementing the method according to any one of claims 1 to 5, characterized in that it successively comprises a coating station (1), a tunnel oven (2), a reserve to variable capacity (4), and deflection rollers (8, 10, 11) to return the strip (3) during treatment to its starting point upstream of the coating station (1). 7. Device according to claim 6, characterized in that it further comprises a welding or bonding station (12) upstream of said coating station (1). 8. Device according to one of claims 6 and 7, characterized in that said welding or sewing station (12) comprises two parallel lower rollers (24) with fixed transverse axes which are located above said strip ( 3), an upper roller (25) which is parallel to the first two (24), which is located between them in the longitudinal direction and which passes under said strip (3), means for moving up said lower roller (25 ) from its normal position ofi it is substantially below said upper rollers (24), and vice versa, and a welding or bonding device (23) disposed transversely with respect to said strip (3> between said lower rollers (24> and said upper roller (25) when the latter is in the high position.  9. Device according to one of claims 6 to 8, characterized in that it comprises locking clamps (26) for clamping said strip (3) against said lower rollers (24). 10. Device according to one of claims 6 to 9, characterized in that in the vicinity of said welding or sewing station (12), it comprises means for receiving at least one supply coil (27), at least one take-up reel (20) and / or at least one interlayer reel (21, 28>.