FR2570323A1 - Improvement to the dispensing of plastic materials, especially for the manufacture of multiple-glazing sealing strips - Google Patents

Abstract

The invention relates to the dispensing of a low-viscosity elastomer at a constant specified rate, apart from intermittent stoppages. In order to do this, the elastomer, having the desired viscosity characteristics, is stored continuously in a variable-volume storage container, despite dispensing stoppages, at an average rate which is possibly less than the dispensing rate when the outlet is open. It applies to the supplying of a bead of elastomer intended to form multiple-glazing inserts.

Description

PERFECTED! #ENT IN THE DISTRIBUTION OF PLASTICS
ESPECIALLY FOR THE MANUFACTURE OF SEALS
MULTIPLE WINDOWS
The present invention relates to the distribution of an elastomer and in particular its distribution at a constant determined flow rate between distribution stops, this elastomer of the butyl rubber type being in particular intended for the manufacture of a seal for multiple glazing.

 Multiple glazing consists of two or more sheets of glass arranged parallel to each other, at a certain distance from each other. Interleaves are provided between the glass sheets and at their periphery to maintain the desired distance between them and seals ensure the tightness of the enclosed spaces. The spacers can be metallic profiles, but can also be continuous plastic cords, in particular based on butyl rubber, these cords contributing at the same time to sealing and thereby strengthening the action of the seals also in material plastic, in particular silicone or polysulphide, placed outside the spacers.

 Such glazing with seals and spacers made of plastic materials are in particular described in French patent publications 1,439,844, 2,211,413, 2,294,313.

 The interlayer is a calibrated bead, precisely deposited on a sheet of glass, at its periphery, successively on each of its rectilinear sides. In the angles the removal is interrupted and the cord is guided in its turn, without being cut, so as to have the same dimensional characteristics as in its rectilinear portions and to present an aesthetic appearance.

 The installation of the interlayer in the corners of a glazing is described in the publication of French patent 2,294,140.

 During the execution of the turn, the cord distribution means are stopped; they are put back into action to continue laying the cord along the next rectilinear edge of the glazing. The difficulties in laying the bead lie mainly in the sufficiently rapid reheating of the plastic material, initially thick, hard (hardness of the order of 700 Shore), with high viscosity, to supply the production lines for multiple glazing production lines , at the necessary flow rate, a cord of said plastic material, perfectly calibrated, with a determined viscosity which in any event must be much lower than initially. The difficulties are all the more important as the speed of the chains is higher and that the height of the bead which defines the thickness of the blade of gas enclosed in the multiple glazing is greater.

 Up to now, extruders or extruders have been supplied, powered by large motors capable of providing significant forces, using small quantities of plastic material, easily and quickly reheatable to be able to meet the demand for cord. However, the increase in the speeds of the production lines and at the same time the growing demand for more insulating glazing having thicker enclosed air or gas layers, therefore requiring higher cords, means that the reheating of the plastic material 'is more fast enough and that the already significant means of driving extruders or extruders are no longer sufficient.

 In addition, the supply of said extruders or extruders with small amounts of plastic material, requires frequent restocking, which results in yield losses.

 The present invention aims to remedy the drawbacks and inadequacies of the previous installations, in particular large and even excessive material to respond to the stops and resumptions of supply of the cord at the passage of the angles of the glazing, material with performances however insufficient to meet the increase chain speeds and heights of cords.

For this, it offers to store continuously plastic material having the necessary viscosity characteristics or close to what is necessary to form the bead, in a store.
of variable volume, close to the place of supply of the cord, continuously as long as the maximum possible volume is not filled, despite frequent stops in the distribution of the cord, at an average flow which may be lower than that at which the cord when this is issued.

 It also proposes a device for implementing this process, in which the plastic material distribution circuit comprises a magazine consisting of a reservoir closed by a sliding piston inside this reservoir, recalled in the inside said tank by a cylinder type return means.

 The return force of the piston is constant and such that the pressure it exerts on the plastic material is less than the pressure under which said plastic material is supplied to the store.

 Preferably, this magazine is coupled to a means which continuously supplies it with plastic material, this supply means consisting of a heating piston equipped with a material outlet, intended to be applied with pressure against the viscous material. high contained in an enclosure, this piston having a shape such that it delimits a volume of material whose section is all the more reduced as it is closer to the outlet, this piston having on its face in contact with the material , heated appendages which plunge into said material.

 In a particular embodiment, this piston has a conical shape and the heating appendages directed along the axis of movement of the piston are included # inside the volume delimited by the piston.

The invention will now be described in more detail with reference to the accompanying figures which represent Figure 1: a diagram of the store with variable volume, Figure 2: a diagram of the entire distribution system of ~ my
third plastic
Figure 1 shows schematically a store M with variable volume, arranged on the distribution circuit of a plastic material, preferably at the end of this circuit close to the place of use of said plastic material.

 This store M comprises a tank 1, preferably cylindrical for reasons of ease of sealing, provided with an inlet opening 2 and an outlet 3. Inside this tank 1 can move a piston 4 traversed over its entire length by a channel 5 for supplying the plastic material which opens out inside the tank 1. This channel 5 is connected at its upstream end to means for supplying the plastic material, not shown on this figure 1.

 The piston 4 is recalled inside the tank 1 by a system exerting a constant force, in particular one -or several veri-ns and as in the example shown, two jacks 6 and 7 each connected on the one hand to the tank 1 and on the other hand to the piston 4. To allow the fixing of the jacks 6 and 7, the downstream end of the tank 1, therefore close to its outlet 3, is crimped in a base 8, while the rear end of the piston 4 is surrounded by a plate 9; the jacks 6 and 7 arranged on each side of the tank 1 and appearing thereto, being fixed by one of their ends to the base 8, by the other end to the plate 9.

 The return force of the piston 4 is such that the pressure which it exerts on the plastic material is less than the pressure under which said plastic material is supplied to the magazine M, for example of the order of half.

 The end of the piston 4 pressed into the tank 1 is equipped with annular segments 10 ensuring the seal between the inside of the tank and the outside, and improving the scraping of the side wall of the tank 1.

 Stops 11 and 12, end of stroke of the piston 4 inside the tank 1, in each of the two possible directions of movement of said piston 4 are also provided. These stops 11 and 12 are biased by contact elements 13 and 14 belonging to the piston 4 and arranged, one 13 determining the maximum insertion position on the rear part of said piston, the other 14 determining the maximum withdrawal position , therefore the maximum volume inside the tank 1, on the front end of said piston 4.

 An intermediate contact element 50 integral with the piston 4 is provided, this element 50 triggering the supply of material to the store M by the supply means placed upstream, without affecting the movement of said piston.

 The contact between the stop 11 and the corresponding element 13 controls the stopping of the injection of plastic material through the outlet 3.

 The contact between the stop 12 and the corresponding element 14 indicates that the volume of material in the store M is at its maximum high level and this triggers the interruption of the supply of material to the store N by the supply means placed in upstream.

 Advantageously to avoid the cooling of the plastic material and even to perfect its heating so that it reaches the desired consistency, the walls of the reservoir 1 as well as those of the channel 5 are heated, for example by electrical resistors 15 and 16.

 Preferably this variable volume store M is coupled to means for supplying the plastic, which operate continuously. These means, visible in FIG. 2, include a heating piston 20 fitted with an outlet 21 for the plastic material; this piston 20 is intended to be applied with pressure against the plastic material contained in an enclosure 22. It has a shape such that it delimits a volume of material whose section is all the more reduced as it is close to the outlet 21 and it has on its face in contact with the plastic master heating appendages 23, which plunge into said plastic.

 In a particular embodiment, this piston 20 is a cone with a circular base. It constitutes the cover of the enclosure 22 and can slide inside said enclosure under the action of jacks 24 connected on the one hand to said piston 20 and on the other hand to a fixed frame which is not shown or more simply to enclosure 22.

 Advantageously, to reduce handling, this enclosure 22 is constituted by the barrel in which the plastic material is delivered.

 The heating appendages 23 preferably have the same direction as that of the sliding movement of the piston 20 inside the enclosure 22, namely, parallel to the axis of the cone that constitutes the piston 20.

 Advantageously, these appendages 23 are contained in the volume delimited by the piston.

 To allow use of all of the plastic material contained in the enclosure 22, its bottom 25 has a shape complementary to that of the piston 20, namely pierced with a well 26 for housing the appendages 23 and conical when said piston 20 is itself conical.

 Possibly to facilitate softening of the plastic, the whole of the enclosure 22, as well as the conduits which connect it to the store M are heated by resistors 27, 28.

 To facilitate the routing of the plastic, pumps 29, 30 in particular with gears, can be mounted on the outlet 21 of the enclosure 22 and also on the outlet 3 of the store II with variable volume. The pump 30 is in particular a positive displacement pump.

 Advantageously also, in order to obtain an immediate, net stop or resumption, of the flow of plastic material through the outlet 3, when the latter is closed, or respectively open, without alteration of the pressure under which the plastic material is maintained, compression cylinders 31, 32 as already described in the French patent published under No. 2 207 799 can be provided.

 The invention operates as described below.

 Plastic material which has already been considerably heated and softened is continuously supplied to the store M through the inlet opening 2 and then through the channel 5, under pressure P, with a substantially constant average flow rate. In certain cases, this average flow rate may be lower than that to which the multiple glazing intermediate cord must be supplied when one is in the cord supply phase, that the outlet 3 is open and that the cord is of large cross section.

If the outlet 3 is open, a cord is therefore supplied and the quantity of plastic material required is extracted from the store M under the effect of the single ~ thrust of the piston 4 recalled by the two jacks 6 and 7 in the case where the means material supply arranged upstream do not charge. In this case the piston 4 advances inside the cylinder thus reducing the volume of stored material. When the stop 11 and the element 50 come into contact, the material supply means arranged upstream are put back into action. If the supplied cord is of large section and the quantity of material delivered through the outlet 3 is greater than the quantity of material supplied to the store
M, the piston continues to advance and the reserve continues to decrease until contact with the stop 11 and the element 13, which interrupts any flow through the outlet 3. If on the contrary the quantity of material delivered through of the outlet 3 is less than the quantity of material supplied to the store M, the piston 4 recedes despite the thrust of the jacks 6 and 7, so that the pressure at the outlet of the store M remains substantially of the order of that exerted by the two cylinders.

 On the contrary, if the outlet 3 is closed and the upstream material supply means flow, the piston recedes as soon as the pressure exerted by the material inside the magazine exceeds that exerted by the jacks, so as to increase the volume plastic material in store M.

 This volume can increase until contact between the plate 14 and the stop 12.

 In normal operation, that is to say during the delivery of the cord for the manufacture of multiple glazing interspersed with stops at each angle of the glazing, the piston 4 oscillates inside the reservoir 1 without practically ever reaching the two stops 11 and 12.

 The volume of this reserve of plastic material in the magazine M, therefore the location of the stops 11, 12, 50 and 14 is determined so that, taking into account the rate of replenishment, the speed of travel of the glazing units to receive a cord, maximum dimensions of said bead, maximum dimensions of glazing, the supply of the bead is possible. Thus, thanks to such a store M, it is possible to supply sufficient plastic material, quickly enough to deposit a continuous bead on a glazing of 4 m × 2.50 scrolling at speeds of the order of 20 or 30 m / min.

 This possible variation in volume of the magazine M allows the continuous operation of the supply means placed upstream at a lower flow rate than that of the cord when it is delivered.

 The conical heating piston 20 is therefore regularly pressed by the jacks 24 inside the enclosure 22, at a speed lower than that which would require intermittent operation. This relatively slow descent speed, the particular shape of the piston 20, the presence of heating appendages which penetrate into the material therefore allow a distribution of plastic material at the end of the outlet 3, at a high flow rate, from quantities high raw material with high viscosity.

 In addition, the possibility of the piston retreating inside the reservoir 1 makes it possible to obtain, through the outlet 3, a plastic material delivered under a substantially constant pressure and determined almost exclusively by the return force of the two jacks.

 This therefore allows a much more constant quality of the plastic material supplied through the nozzle.

Claims (14)

 1. Method for dispensing at low viscosity, a plastic material of the butyl rubber type, with a high but intermittent flow rate from a reserve of said material with higher viscosity, while having a reduced, lower heating power to that necessary for passing the plastics material from its high viscosity to its low viscosity at the speed required by the distribution when the latter is open, in particular for manufacturing a bead intended to form the interlayer of multiple glazing, characterized in that '' it consists in storing plastic material having the necessary viscosity characteristics or close to what is necessary, in a variable volume, continuously as long as the maximum capacity of the variable volume is not reached, at an average flow sometimes lower than that to which the plastic material is distributed when the distribution is open, this average flow rate of low viscosity plastic material being sufficient low so that it can be obtained by applying the available heating power, this variable volume increasing when the distribution is closed and on the contrary being restricted when the distribution is open.  2. Method according to claim 1, characterized in that to supply the variable volume, a limited amount of high viscosity plastic material is heated, an amount the section of which is all the more reduced the closer it is to an outlet by or the heated material is extracted, by means of a pressure exerted on the heated quantity, against the direction of the direction of extraction.  3. Method according to any one of claims 1 or 2, characterized in that all of the plastic in the distribution circuit is heated.  4. Device for dispensing a low viscosity plastic material at a high but-intermittent flow rate from a reserve of said higher viscosity material, in particular for manufacturing a bead intended to form the interlayer of multiple glazing units, characterized in that that it comprises a magazine M consisting of a reservoir 1 closed by a piston 4 sliding inside this reservoir 1, returned to the interior of said reservoir with a constant force by a return means of the jack type.  5. Device according to claim 4, characterized in that the return force of the piston is such that the pressure which it exerts on the plastic material enclosed in the magazine M is less than the pressure under which the magazine M is supplied with material plastic.  6. Device according to any one of claims 4 or 5, characterized in that the magazine M is supplied with plastic material by a supply means comprising a heating piston equipped with a material outlet and intended to be applied with pressure against the high viscosity material contained in an enclosure, this piston having a shape such that it delimits a volume of material whose section is all the more reduced as it is closer to the outlet, this piston having on its face in contact with the material, heated appendages which plunge into said material.  7. Device according to claim 6, characterized in that the piston has a conical shape.  8. Device according to one of claims 6 or 7, characterized in that the heating appendages are directed parallel to the axis along which the piston moves under the effect of the pressure exerted on it.  9. Device according to one of claims 6 to 8, characterized in that the heating appendages are included inside the volume delimited by the piston.  10. Device according to one of claims 6 to 9, characterized in that the bottom of the enclosure has a shape complementary to that of the piston equipped with its heating appendages.  11. Device according to one of claims 4 to 10, characterized in that the conduits and walls which contain the plastic material are heated.  12. Device according to one of claims 4 to 11, characterized in that it further comprises at least one pump, in particular with gears.  13. Device according to claim 12, characterized in that a pump is disposed on the outlet through the conical heating piston, another being arranged at the outlet of the variable volume store.  14. Device according to any one of claims 4 to 13, characterized in that at least one compression and decompression cylinder is disposed at the outlet of the variable volume store.