EP0140785B1 - Winder with controlled compression - Google Patents

Description

The invention relates to techniques for packaging products such as mineral wool felts. These low density products, due to their resilience, are advantageously compressed during storage and transport.

For light felts, a traditional conditioning consists in rolling up the felt on itself by compressing it. Cylindrical rollers are thus formed, the stability of which is ensured by the packaging usually consisting of a sheet of paper or of a polymer material.

If it is advantageous, in terms of size, to strongly compress the felt, the compression ratio chosen must also take into account the thickness recovery capacity of the product during its implementation. The qualities of the felts, in particular the insulating qualities, are in fact a function of their thickness. Experience shows that to ensure a satisfactory thickness recovery when the product ceases to be compressed, it is necessary to limit the compression rates imposed.

The best possible winding for these products is that which, by ensuring uniform compression over the entire length, allows to operate at the highest admissible rate without compromising the quality of the product. It is also the winding which guarantees the quality of the product in a packaging offering the minimum size.

Different means have been proposed to achieve this result.

Typically the felt is led into a space delimited by two conveyor belts and a compression roller. These mats and this roller drive the felt in a rotational movement leading to its winding on itself. The compression roller can move so as to gradually increase the space in which the felt is wound.

To achieve uniform compression of the felt, it is necessary that the pressure exerted by the compression roller increases with the number of turns of the wound felt. The law of growth of the pressure to be applied depends on many parameters.

So far, the means used to increase the pressure exerted are not entirely satisfactory.

In the most usual mode as described for example in patent US-A-3 991 538, the increase in the pressure exerted results directly from the increase in the “diameter of the wound felt. For example, the compression roller is arranged at the end of a movable arm. The crescent felt roller repels the compression roller. A pneumatic cylinder fixed on the arm carrying the compression roller exerts a reaction which tends to oppose the movement of the arm. The pressure in the pneumatic cylinder which is transmitted via the arm and the compression roller to the felt during winding is all the greater the greater the displacement of the compression roller.

Even when such means are refined, it does not succeed in practice to follow satisfactorily the progression necessary to ensure a uniform compression ratio of the felt over its entire length. Typically, there is most often a higher compression in the center of the winding compared to that which is exerted on the part located at the periphery. Given the imperatives of thickness recovery, this leads to reducing the compression on the entire winding. Consequently, the packaged products are either shorter or more voluminous than would be necessary if the conditioning of the felt was perfectly mastered.

Furthermore, an additional difficulty results from the need on certain installations to process various products, the characteristics of which, in particular with respect to compression, may be very different from one another. Under these conditions, with each change of production, it is necessary to modify the mechanical arrangement which imposes relatively long and delicate adjustments.

The invention proposes to provide means for ensuring a more uniform product winding over their entire length. The invention also proposes to provide means conveniently adaptable to the treatment of various products.

To achieve these results, according to the invention, a device is used such that the compression exerted on the felt does not result from a passive reaction, but on the contrary, from a movement of the compression members according to a program well determined by l 'operator. For this purpose, the compression members are associated with motor means capable of ensuring a modification of their relative arrangement so that at any time, during the winding of the felt, the space left available between these members determines for each turn a well-defined compressed thickness, depending on the length of the felt already wound up.

The motor means ensuring the movement of the compression members are controlled by control means associated with measurement means and calculation means. This movement takes place according to a predetermined program.

The calculation means establish the operating instructions of the driving means as a function of various variable parameters of the installation. One or more of these parameters are measured directly by appropriate means during operation, and are transmitted for processing to the calculation means. Other variable instructions can also be entered by the operator.

More specifically, the invention relates to a device for forming rollers from strips of compressible material comprising a set of at least three members delimiting a space in which the winding takes place, these members being animated so that in contact with them the strip is wound on itself in the space which they delimit, at least one of these members being movable relative to the others during operation, these members being respectively a first conveyor on which the belt is transported to this space, a second conveyor arranged at the end of the first and making an acute angle with the first and a compression roller, the compression roller being located in the angle of the conveyors (see US-A-3,991,538), characterized in that the compression roller is moved by motor means such as a hydraulic cylinder or the like directed by means of control means by calculation means which operate s According to a program in memory and from the measurements transmitted by sensors according to the course of the formation of the roller and a position encoder transmitting a signal corresponding to the position of the compression roller.

In the prior literature, for example in patent US-A-4164177, there is the description of automated installations for the formation of felt rolls, but the devices considered are not of the type of those used according to the invention. In particular, these prior devices are distinguished by the means used for the formation of the winding. Being different in the means used, these installations are also different in the automated systems used and in the functions which they fulfill.

• la figure 1 est une vue schématique d'une enrouleuse telle que celle mise en oeuvre selon l'invention,
• la figure 2 est un schéma montrant différents éléments commandant le fonctionnement de l'enrouleuse,
• la figure 3 est un schéma présentant divers paramètres géométriques pris en considération dans la détermination du programme de commande de l'organe de compression, dans un mode de réalisation de l'invention,
• les figures 4a à 4d sont des schémas montrant les variations d'épaisseur des produits déconditionnés suivant qu'ils ont été enroulés par une technique selon l'invention ou par une technique traditionnelle.

The invention is described in more detail below, with reference to the drawing boards in which:

• FIG. 1 is a schematic view of a winder such as that used according to the invention,
• FIG. 2 is a diagram showing different elements controlling the operation of the winder,
• FIG. 3 is a diagram showing various geometric parameters taken into account in determining the control program for the compression member, in one embodiment of the invention,
• FIGS. 4a to 4d are diagrams showing the variations in thickness of the unpackaged products depending on whether they have been wound up by a technique according to the invention or by a traditional technique.

The winder shown in Figure 1 can be used for the formation of rolls of glass wool felts or similar compressible products.

This reel can be placed directly at the end of a production line for these felts. The manner in which the fibers are produced is immaterial to the invention. It suffices, in particular after the polymerization step of the binder which makes the fibers adhere to each other, that the felt thus formed has good resilience, in other words that it can undergo significant compression and then resume most of its initial thickness when it ceases to be compressed.

It goes without saying that among the mineral felts, only those that are described as "light" lend themselves to this mode of conditioning. For densities greater than 30 kg / m ³ and thicknesses greater than 20 mm, even if the packaging includes a certain compression, this can only be exerted on flat products. In the same way, the felts coated on at least one of their faces can be rolled up provided that the coating can undergo a significant bending without damage. This is particularly the case for Kraft papers, coatings of films of aluminized or non-aluminized polymer materials, and generally thin and flexible coatings.

The felt 1 progresses on the conveyor 2 in the direction indicated by the arrow. The conveyor 2 is set in motion by the motor 3 by means of a belt 4 and the drive drum 5.

A chassis 6, spanning the conveyor 2, supports two arms 7 and 8. These arms are mobile in rotation respectively around the axes 9 and 10 carried by bearings fixed on the chassis 6.

The arm 7 carries a conveyor 11 whose end furthest from the axis 9 is located opposite the end of the conveyor 2 at a short distance from the latter. This distance is as short as possible. Its purpose is to facilitate the initiation of the winding by leaving the felt a minimum of space. This distance must however be sufficient to avoid any risk of friction of the conveyors on one another.

The conveyor 11 is inside an envelope which is only partially shown in the figure for reasons of clarity. The limit of the missing part of the envelope is indicated in dotted lines.

In this position, the faces of the conveyors form an angle of less than 90 ° between them. This angle is advantageously between 40 and 80 ° and preferably close to 60 °.

The conveyor 11 is set in motion by the motor 3, by means of a deformable articulated transmission not shown. This articulated transmission is such that it allows the tilting of the arm 7 in the manner described below.

. A jack 13 fixed on a support 33 integral with the chassis 6 makes it possible to tilt the arm 7 so as to separate the end of the conveyor 11 from that of the conveyor 2. In the separated position, the distance separating the two conveyors is greater than the diameter of the felt rollers formed to allow the evacuation of the latter.

The power supply and the control of the jack 13 are not shown.

The arm 8 comprises two identical parts located on either side of the arm 7 which they frame.

The lower ends of the two parts of the arm 8 carry two rollers 14 and 15. These rollers are rotated by means of chains, not shown, located along the arm itself. The drive is provided by the motor 3. The return wheels of the movement of the chains are coaxial with the axis of rotation 10 of the arm 8, so that a movement of the arm 8 can be done without modifying the tension of the chains . A variable speed drive, not shown, is interposed on the transmission system.

The arm 8 is extended by a counterweight 17 which balances it and makes its movement easier.

According to the invention, the space in which the felt strip is wound up is delimited by two conveyors and a roller. If necessary, at least one of the conveyors could be replaced by a roller fulfilling the same function. Despite a slightly more complicated mechanism, the use of conveyors is advantageous for several reasons.

A first reason is due to the fact that even if the rollers are of relatively large dimensions, the contact with the wound strip takes place on a convex surface which tends to deform the felt more than does a conveyor which has a flat surface. This is important for proper roll formation.

It should be noted in passing that the use of large diameter rollers has the drawback of leading to a winding space which is relatively large in the position corresponding to the start of the operation, which does not allow perfectly satisfactory control of the conditions. imposed throughout the winding.

Another reason is, that by using one or two conveyors instead of one or two rollers whose relative positions are fixed, the support points of the wound felt evolve as a function of the progress of the winding. If one starts from a provision such that the three support points are distributed regularly around the periphery of the felt roll, this regularity disappears very quickly and the maintenance is less well ensured.

It is possible to modify the position not only of the roller which, within the framework of the invention, we call compression roller, but also the set of rollers (or conveyors) with respect to each other so that the points d 'support remains well distributed but this requires a complicated mechanism.

It therefore seems preferable to use conveyors whose relative positions may remain fixed. The increase in the diameter of the felt roll is in fact accompanied by a displacement of the support points on the conveyors, displacement which tends to restore a balanced arrangement of these support points.

The third support point on the compression roller also moves in a movement which maintains this good arrangement. Schematically in this ideal arrangement, the support points are equidistant from each other. To get closer to this arrangement, the distance from the compression roller to the axis of rotation is sufficiently large and the position of this axis is preferably such that the displacement takes place substantially along the bisector of the angle of the two conveyors.

In the following description, we will only refer to the case shown in Figure 1, that is to say one in which the means delimiting the winding space are constituted by two conveyors and a roller, in accordance to the device according to the invention.

In the previous embodiments, a pneumatic cylinder 18 mounted on a support 19 secured to the chassis 6 makes it possible to move the arm 8 through its rod 20.

Still in the previous modes, the pneumatic cylinder intervenes purely passively. When the arm 8, pushed back by the wound felt 21, pivots about the axis 10. The air pressure in the jack increases and, by reaction, the pressure on the felt increases.

According to the invention, the movement of the arm, and consequently the pressure exerted on the felt, follow a preset program. For this, the position of the arm 8 is precisely defined at each instant.

The motor device 18 is thus advantageously a hydraulic cylinder or an electric motor controlled in position. Their power is chosen to be high enough so that the pressure exerted by the felt is practically without influence on the operation of the compression roller, unlike what occurs with the prior pneumatic cylinder.

The supply of the hydraulic cylinder in the case of the invention is carried out in the traditional way by a proportional distributor and a hydraulic group not shown.

In general, according to the invention, the movement of the arm 8 is a function of the length of the wound felt and so that the thickness of each turn of the winding is practically constant.

The winder according to the invention thus comprises at least means making it possible to determine at any time the length of felt wound, a sensor determining with precision the position of the arm 8, and calculation means in which the movement program of the arm 8 is stored. The calculation means receive the signals relating to the length of felt and of the position signals of the arm, and elaborate in response a position instruction of this arm, instruction which is executed by the motor means (hydraulic cylinder, electric motor) indicated above. .

A diagram for controlling the operation of the reel is shown in Figure 2.

A photoelectric cell 22 placed at the entrance to the space in which the winding takes place and above the carpet 2, detects the arrival of a strip of felt and triggers the progress of the ordered. The signal is transmitted to programmable calculation means 23.

The calculation means 23 also receive from a sensor 24, for example a tachometric dynamo, a signal for the speed of progression of the conveyor 2 and consequently of the felt.

The combination of the felt arrival signal and the speed gives the length of the coiled felt.

The calculation means also receive a signal from a position encoder 25 determining the angle of the arm 8 carrying the compression roller with respect to a reference position.

If necessary, an additional sensor makes it possible to measure the initial height of the compression roller with respect to the conveyor 2. This determination is necessary when this height is modified to take account of changes in thickness of the products treated.

In Figure 1 the means for changing the initial height of the axis 10 of the arm 8 are shown at 29. This is for example a system driven by a screw motor.

Of course, the measurement of the initial height of the arm 8 as well as that of the speed of the conveyor belt 2 can also be introduced by the operator directly into the data supplied to the calculation means. Indeed, these parameters usually remain constant during long periods of operation. Their variations are controlled by the operator who can therefore modify the data entered in the calculation means accordingly.

The means of calculation as a function of these data and of the control algorithm introduced into memory establish instructions which are sent to the commands 26 controlling the operation of the motor means 27 actuating the displacement of the compression roller, and also the means 28 actuating the movement of the back conveyor 11.

The operation of the winder according to the invention is established as follows.

The felt strip 1 carried by the conveyor 2 passes in front of the photoelectric cell 22 and triggers a measurement of the time elapsed in the operating cycle.

Before entering the space defined for winding, the felt strip is compressed by means of the roller 15.

The roller 15 is carried by the arm 8. It is driven like the compression roller 14 and rotates in the opposite direction. The roller 15 makes it possible to prevent the felt from coming into contact with the roller 14 when it is introduced into the space in which the winding takes place. Indeed, the direction of rotation of the roller 14 is such that it would tend to repress the felt instead of facilitating its entry into this space.

The speed of rotation of the roller 15 is adjusted so that the speed at the periphery corresponds substantially to that of the conveyor 2.

The felt driven by the conveyor 2 strikes the back conveyor 11 and folds back on itself. From the conveyor 11, the end of the felt is directed towards the compression roller 14. The roller 14 forces the felt to bend again on itself. From the roller 14, the end of the felt is returned to the conveyor 2 where it comes into contact with the upper face of the felt.

A first loop of felt is thus formed. The roller then progresses in successive thicknesses which are added to each other.

Very soon after the start of winding, the compression roller 14 moves away from its initial position to take account of the increase in volume of the wound felt. The movement is done in the direction indicated by the arrow F by tilting the arm 8. The movement is programmed in order to ensure that all the turns of the roll formed have substantially the same thickness.

It should be noted that the thickness imposed is not necessarily exactly that which is found in the felt roll. It is indeed necessary to take into account the elasticity of the product and the deformations it presents during winding. In practice, the thickness imposed is generally less than that of the felt in the completed roll, and which is no longer maintained by the conveyors and the compression roller.

By deviating from its initial position, the arm 8 progressively increases the distance between the conveyor 2 and the roller 15. This distance becomes such that from a certain moment the roller 15 ceases to be in contact with the felt. The distance is then also sufficient so that the felt carried by the conveyor 2 does not come into contact with the compression roller 14.

At the end of the felt strip 1 a paper or polymer envelope is deposited on one of the faces of the felt. The length of this envelope is such that it completely covers the exterior surface of the roller in a known manner.

During this time, the roller having reached its final dimension, the movement of the arm 8 is interrupted.

The establishment of the envelope on the felt being made, the conditioning of the felt strip is completed for example by gluing the envelope so that it maintains the felt in its final compressed form. The arm 7 moved by the jack 13 rocks. The felt roll which is driven by the conveyor 2 is discharged through the opening cleared between the conveyors 2 and 11.

At the same time, the arm 8 is returned to its initial position. Finally, the arm 7 is also returned to the working position. The reel is ready for processing a new strip of felt.

The rocking movements of arm 7 and return of arm 8 are executed very quickly so that the time interval separating two strips of felt can be very reduced. In practice, the entire ejection of the roll formed and the return to the working position does not exceed two to four seconds.

In these operations, the felt kept compressed is not in strictly cylindrical form. It undergoes a slight crushing at the points of contact with the conveyors and the compression roller. We have seen that the use of conveyors 2 and 11 makes it possible to maintain a relatively large contact surface, in particular compared to that of the compression roller 15. This indeed must necessarily have a small radius of curvature in order to be able to define a Small winding space at the start of the process.

To minimize deformation of the roll during preparation, it may be advantageous to establish slight differences in speed between, on the one hand the conveyor 2, and on the other hand the conveyor 11 and the roll 14. By making sure that the speed of the conveyor 11 and of the roller 14 is slightly higher (in general less than 5%) than that of the conveyor 2, the felt is kept taut between these successive contact points and the appearance of significant deformations which can be harmful is avoided the regularity of the winding.

These possible slight differences in speed make it possible to compensate for a possible sliding of the felt on the conveyor 11 or the roller 14, slipping due for example to the small contact surface.

The envelope introduction system is shown diagrammatically in FIG. 1. The cut and partially glued sheets coming from a dispenser, not shown, and also controlled by the calculation means, are conveyed by a conveyor belt 30. They then pass on belts 31, in known manner, so that they are deposited on the end of the upper face of the felt strip at the moment when the latter will enter the winding space.

The envelope sheet is driven by the felt. It is taken in the last turn. This sheet extends beyond the end of the felt strip over a length greater than that of the periphery of the roll, so that it completely envelops it.

We indicated previously that the displacement of the compression roller followed a law making it possible to ensure an equal thickness of the turns. In the case shown in Figure 1, the law chosen is advantageously the following. The symbols used are those shown in Figure 3.

In FIG. 3 are shown schematically the back conveyor 11, the horizontal conveyor 2, the compression roller 14 and the arm 8.

Knowing the final radius R _F of the roll formed and the length of the fiber sheet N, we deduce the thickness E of each turn:

soit:

To have E constant, the movement of the arm 8 carrying the compression roller must be such that at all times the radius R of the roller already formed for a length 1 of the felt is:

is:

A calculation based on the geometry of the system as presented in FIG. 3 makes it possible to express the variations of the angle A made by the arm 8 with the vertical at any time. The calculation means check at all times that the position of the arm actually meets this condition.

avec :

The value of the angle A as a function of the different geometric parameters is of the type:

with:

• L : longueur du bras 8 entre l'axe de rotation et celui du rouleau de compression,
• H + h : distance de l'axe de rotation 10 au tapis convoyeur 2,
• α : angle formé par les directions des deux convoyeurs 2 et 11,
• D : distance séparant le point de concours de la direction des faces des convoyeurs à la projection du centre de rotation du bras 8 sur la face du convoyeur 2.

In these expressions, the different terms denote respectively:

• L: length of arm 8 between the axis of rotation and that of the compression roller,
• H + h: distance from the axis of rotation 10 to the conveyor belt 2,
• α: angle formed by the directions of the two conveyors 2 and 11,
• D: distance separating the point of competition from the direction of the faces of the conveyors to the projection of the center of rotation of the arm 8 on the face of the conveyor 2.

Of course, this expression of the angle of the arm 8 with the vertical only corresponds to the configuration shown. When the various elements constituting the winder are in different - relative positions, another expression must be used for the basis of the program introduced into the calculation means. The preceding expressions are given only as an illustration of the method used.

The geometric conditions which have just been considered constitute only a series of parameters taken into account by the calculation means. The main other parameters include those which depend on the nature of the felt rolled up: initial thickness, total length of the strip, mass per unit area, admissible compression ratio, etc. The values of these parameters can be entered directly by the operator, either separately or globally, by referring to a code to which all the values stored in memory correspond, each product having its own code.

The packaging technique according to the invention was the subject of tests on an industrial line for the production of glass fiber felts.

The felts used consist of fibers produced by a centrifugation technique. In this technique, the molten material is passed through a centrifuge carrying at its periphery a large number of orifices of small diameters. Under the effect of centrifugal force the material is projected through these orifices out of the centrifuge in the form of filaments. These fine filaments are further drawn by hot gas streams along the periphery of the centrifuge at high speed. The fibers produced are collected on a conveyor. On their way to the conveyor they are coated with a binder. The fibers collected are then passed through a treatment chamber in which the binder is polymerized. The sheet of fibers thus formed is cut to the appropriate dimensions. It is this sheet which is wound in the manner described according to the invention.

In industrial plants, usually several centrifugal devices are aligned over the same conveyor.

In the tests carried out, four or five centrifuges were used simultaneously.

The felts prepared during these tests are relatively light; their density varies from 6.8 kg / m ³ to 10.8 kg / m ³ . The fibers are fine; the micronaire is either 2.5 / 5 g or 3.1 / 5 g.

The felts contain 4.5% by weight of binder.

The nominal thickness, that is to say the thickness guaranteed to the user, is for all these products 90 mm. In fact, to take account of the incomplete thickness recovery after storage, an additional thickness is systematically provided in the felt before winding.

For products wound in the traditional way, this extra thickness is all the more important as it must compensate for the defects of the winding. It is indeed necessary to be able to find at least the nominal thickness at any point of the unwound felt. To take account of the fact that traditionally the first turns of the roller are more strongly compressed and regain their thickness less well, the initial felt in the prior techniques must have a large excess thickness which can reach or exceed 60%.

By way of comparison, the tests were carried out on the same products on a winder according to the invention and on a winder of traditional type in which the felt roll undergoes the reaction of a pneumatic cylinder, the pressure exerted by the roll of felt is bigger.

In the following table appear the thicknesses measured after unpacking for the products A wound in the traditional way and the products B wound according to the technique of the invention. Of course in both cases the length of the felt strip and the final diameter of the roll are the same. In this table, the relative deviation is also indicated.

For these tests, the thickness measurements are carried out in accordance with French standard NF-B-20.101. According to this standard, the thickness is measured under a conventional pressure of 50 N / m ² . Measurements are made every 250 mm lengthwise, and 175 mm from the edges widthwise.

The values given in the table correspond to the average of the values measured over the entire length of the felt strip.

In all these examples, it can be seen that, all other conditions being equal, the winding carried out under the conditions allows a substantial thickness gain gain.

An even more remarkable effect is that the thickness of the unrolled product is much more regular over the entire length. The over-compression of the first turns, which constitutes a relatively frequent defect in the traditional winding mode, has practically disappeared. This regularity is particularly advantageous insofar as it can lead, for example, to a reduction in thickness of the initial felt or to a greater uniform compression.

The profiles of the felts A and B for these four products are shown in Figures 4a to 4d.

The values plotted on the graphs correspond respectively to the averages determined over five equal sections distributed over the entire length of the strip of felt. The results are written from left to right, the left part representing the end located in the center of the roll and the right part representing the end.

In these figures it can be seen that the uniformity of the product has been considerably improved, the thickness recovery is on the whole slightly increasing from the part corresponding to the first turns to that corresponding to the final turns of the roller. This can possibly be explained by the fact that in the program used for these tests, the only condition fixed is a constant thickness of turn. To take account of the variable radius of curvature as the winding and the resulting deformation differences, it may be preferable to program the winding so that the thickness of the turns is slightly decreasing from start to the end of the formation of the rollers.

The means proposed according to the invention also have the remarkable feature that they allow a very convenient modification of operating conditions. For this, it suffices to modify or complete the instruction program stored in the calculation means. No intervention is necessary on the mechanical elements of the device.

For this reason, finding the winding conditions best suited to each type of product can be done without difficulty.

Claims (4)

1. Apparatus for forming rolls from strips (1) of compressible material comprising an assembly of at least three members (2, 11, 14) defining a space in which the rolling takes place, the said members being moved in such a way that upon contact the strip (1) is rolled on itself within the space which they define, one of the said members (14) at least being movable in relation to the others during the course of operation, the said members being respectively a first conveyor (2) on which the strip (1) is transported as far as the said space, a second conveyor (11) disposed at the end of the first and forming an acute angle with the first and a compressing roller (14), the compressing roller (14) being situated at the angle made by the conveyors, characterised in that the compressing roller (14) is displaced by motor means such as a hydraulic jack or similar means (18) under the direction of control means (26) via calculating means (23) which operate according to a memory-stored programme and on a basis of measurement transmitted by pick-ups (22, 24) which follow the progress of formation of the roll (21) and a position coder (25) which transmits a signal corresponding to the position of the compressing roller (14).

2. Apparatus according to Claim 1 in which the compressing roller (14) is disposed on an arm (8) which is operated by a hydraulic jack (18) fed by a proportional distributor and a hydraulic assembly.

3. Apparatus according to Claim 2 in which the position coder (25) rigid with the arm (8) carrying the compressing roller (14) transmits to the calculating means (23) signals corresponding to the position of the arm (8) while it is rotating.

4. Apparatus according to one of Claims 1 to 3, in which the pick-up used comprise detecting means (22) which make it possible to fix the start of introduction of the strip into the space in which the rolling takes place, means coupled on the one hand to time measuring means and on the other to means (24) for measuring the progress of the strip, these means jointly determining the length of the felt which has been rolled.

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