FR2567448A1 - Dispenser for a high-viscosity elastomer - Google Patents

Abstract

The present invention relates to the supply of a high-viscosity pasty substance, especially an elastomer of the butyl rubber type, from a container containing it, with a view to working it and dispensing it. It provides for heating up a limited volume of high-viscosity material, the cross-section of which volume becomes smaller as it approaches an outlet via which the heated-up material is extracted by virtue of a pressure exerted on the heated-up volume. The invention also provides a device for implementing this method. It applies to the dispensing of a bead of plastic material serving as insert for multiple glazing.

Description

DISTRIBUTION OF A HIGH VISCOSITY ELASTOMER
The present invention relates to the supply of a pasty substance with a high viscosity, in particular an elastomer of the butyl rubber type, from a reservoir containing it in order to work and distribute it, in particular to form a continuous bead intended for serve as a spacer between two consecutive glass sheets of multiple glazing.

 It is known to work a material such as butyl rubber, and for example to extrude therefrom a continuous bead of gauges to space the glass sheets in multiple glazing using a worm extruder, to preheat the raw material to pass through the extruder.

 Thus, a bead can be supplied quickly enough to deposit it continuously directly on the edge of sheets of scrolling glass facing the extruder.

 It is also possible, after each extrusion stop at the corners of the glass sheets, to restart the supply of cord and its laying along another straight side of said glass sheets, practically instantaneously.

 However, to obtain these performances, it is necessary to operate with extruders having reservoirs for raw materials intended to feed the worm, of small dimensions and reserves of low raw materials. Thus, it is commonly used with butyl rubber bars of the order of 10 kg capable of being quickly heated to supply the endless screw of the extruder quickly and at the desired rate.

 Such a process is for example described in the French patent publications FR 2 294 313 and FR 2 294 140.

 The use of reduced reserves of material to obtain both the malleability suitable for feeding a plodder and the flow sufficient to satisfy the needs of an automatic chain, requires frequent restocking stops on the one hand, hence yield losses, and costly packaging on the other hand.

 Furthermore, the cord output speeds currently obtained, although already high, are difficult to increase because of the difficulty in reheating the plastic material, which makes it impossible to increase the rate of automatic production lines for multiple glazing, whereas the other stations in these same chains are not saturated and would accept higher speeds.

 It is also known, but for plastics with a much lower viscosity, of the polysulfide type which have a practically liquid consistency, to exert pressure on a reservoir containing said plastics, using a flat plate, forming tank cover, heating or not, able to enter said tank. The plastics are thus propelled through an outlet orifice with which the tray is provided.

 But when the plastics are much thicker, which is the case for those of the butyl rubber type whose Shore hardness at ambient temperature is of the order of 700, the pressure exerted by the plate and the possible heating which does not affect that a thin layer of material, have no effect, so that the flow through the outlet is practically zero.

 The present invention aims to improve the production lines of multiple glazing by avoiding the drawbacks encountered in roving on current machines, namely limit flow rates, frequent replenishment in particular.

 In addition, it makes it possible to supply with greater certainty of good quality, plastic cords and consequently multiple glazing.

 For this, it proposes to extract from a large reserve of pasty material of high viscosity, in particular an elastomer of the butyl rubber type, of the heated material of lower viscosity, for example to supply a working machine with said material, in particular a extruder to form a bead intended to serve as an interlayer between two consecutive sheets of glass in multiple glazing, by heating as and when required, a limited volume of material with high viscosity, the volume of which is as much more reduced than it is closer to the outlet, in particular towards the machine for working the material such as a extruder, a pressure being for this applied to this limited volume and heating up.

 The invention also provides a device for implementing this method, this device comprising a heating piston equipped with a material outlet, for example to a material working machine such as a extruder, intended to be applied against the material at high viscosity to constitute one of the walls or an element of one of the walls of the large reserve of pasty material with high viscosity, this piston having a shape such that it delimits a volume of pasty material whose cross section is all the more reduced that it is closer to the outlet with which said piston is provided, this piston also having on its face in contact with the material, heating appendages which plunge into said material, and this piston being applied with pressure against the material contained in Reserve.

 In a particular embodiment, the material reserve is a barrel, in particular that in which the said material is delivered and the piston is arranged as a cover on the barrel.

The piston may have the shape of an eonic surface, in particular the surface of a cone with a circular base.
Advantageously, the wall of the reserve opposite the piston, in particular the bottom of the ftt, has a shape complementary to that of the piston equipped with its heating appendages.

The invention will now be described in more detail with reference to the accompanying figures which represent Figure 1: a schematic overview of a milking installation.
elastomer of the butyl rubber type for example
for the manufacture of a cord used as an inter
calaire in multiple glazing, Figure 2: a section of the elastomer preparation station in view
of the feed for example of a extruder, Figure 3: a more detailed section of the piston belonging to the station
shown in Figure 2.

 FIG. 1 is a diagram showing the circuit of an elastomer of the butyl rubber type, for example in an automatic production line for multiple glazing with plastic seals.

 Elastomer 1 is available in a tank 2 and in the example of manufacturing multiple glazing units, it is a question of supplying from this elastomer 1, initially in the tank 2 in the form of a thick, hard paste (its Shore hardness can be greater than 600C and for example of the order of 70), a cord 3 calibrated, continuous, softer (its Shore hardness is of the order of 30 to 50), of much lower viscosity (Mooney viscosity greater than 1150 after 8 min and at 400C as defined in French patent publication No. 2,294,313), this cardoon 3 being intended to be deposited on the periphery of a glass sheet 4 to form an interlayer between this sheet 4 and another sheet, not shown, applied to the other side of the cord 3, parallel to the first sheet 4.

 To do this, use is made of a heating piston 5 applied with pressure to the material 1 of the reservoir 2. This piston 5 is provided with an outlet 6 connected by a conduit 7 to a extruder 8 with a worm screw 9 which delivers at its outlet , through a nozzle 10, the calibrated bead 3, having the desired viscosity, and which deposits it on the glass sheet 4 in relative movement relative to said nozzle 10.

 A pump 11, for example with gears, is placed on the duct 7, near the outlet 6 to help propel the material 1 into the said duct 7.

 The heating piston 2 reservoir 5, object of the invention, will now be described in more detail in connection with FIGS. 2 and 3.

 The heating piston 5 constitutes a wall and preferably for reasons of simplicity and efficiency, the upper wall of the tank 2. It is of a size such that it can penetrate inside the tank 2, seals 12 sealing being provided between the edges of said piston and the walls of the tank 2.

 It is applied with pressure against the material 1 contained in the tank 2. For this, said piston is subjected to the pressure of jacks, for example two in number, 13 and 14, arranged on each side of the tank 2, fixed with on the one hand to a base 15, in particular which also supports the reservoir 2, on the other hand thanks to a gantry 16, at the upper part of the piston.

 It is of such a shape that it delimits a volume of material 1, the section of which is all the more reduced the closer it is to the outlet 6 which equips said piston 5.

 It can have the shape of a conical surface in particular either a cone or a pyramid depending on whether the tank 2 is cylindrical or prismatic, the outlet 6 being arranged at the tip of the cone or of the pyramid.

 The surface of this piston 5 is equipped with heating means such as electric resistors 17.

 This surface is further provided with appendages 18 also heated, directed towards the interior of the tank 2.

 Preferably, for better heating, heating means such as resistors 19 are incorporated in these appendages 18, for example inside cavities 20 provided for this purpose.

 These heating appendages 18 can have various lengths. Preferably, they are all the longer as they are located closer to the axis of the cone or of the pyramid formed by the piston 5.

 Advantageously to facilitate the housing of the piston 5 in the tank 2, in particular at the end of the race, when it comes into contact with the wall of the tank 2 which is opposite to it, in this case the bottom 21 of the tank 2 in the configuration shown in FIG. 2, these appendages 18 are contained inside the volume delimited by this piston 5.

 To facilitate the translational movement of the piston 5 inside the tank 2 under the thrust of the jacks 13 and 14, these appendages are directed parallel to the direction of movement of the piston 5.

 Preferably, the outlet 6 is arranged in the center of the piston 5.

 To assist in the total emptying of the reservoir 2 under the effect of the piston 5 which is pushed, the wall of the reservoir 2 opposite the piston, in particular the bottom 21 in the configuration shown, has a shape complementary to that of the piston. If it does not have this desirable shape, before filling the tank 2 with the material 1, there is inside the tank, against this wall, a core 22 having the desired shape.

 FIG. 3 shows a more detailed view of the piston 5. It can be seen that in the embodiment chosen, the angle at the top of the piston is of the order of 450. To facilitate the movement of the piston 5 inside the elastomer 1, the ends of the appendages 18 are profiled.

 The seal between the piston 5 and the reservoir 2 is for example obtained by a double seal 12 in particular made of rubber or of a material of the same type, placed in peripheral grooves 23 and 24.

 For sealing reasons, a cylindrical tank 2 will advantageously be chosen. It may in particular be constituted by the barrel in which the material 1 is delivered.

 Optionally, to facilitate the preparation of the elastomer for its passage through the extruder 8, the reservoir 2 can be heated, for example by being immersed in a thermostatted bath 25, as is the conduit 7 as well as the extruder 8.

 Instead of the extruder 8, any other means capable of providing a calibrated cord can be provided, in particular a pump.

The device works as follows
A barrel filled with material 1, having a bottom of suitable shape or having received before filling with material 1, a core 22 of suitable shape, is delivered, it is arranged near the place where it is desired to produce the cord 3.

 It can be surrounded by heating means or immersed in a thermostat-controlled bath 25. The upper cover of the barrel is removed and replaced by the crew comprising the piston 5 attached to the gantry 16 and the jacks 13 and 14. The heating means 17 and 19 are powered up. Under the effect of the jacks 13 and 14, a pressure is exerted on the material 1. The heating appendages 18 soften the material, which under pressure, as the piston advances, flows along the conical wall of said piston and is channeled towards the outlet 6 due to the progressive restriction of the section of the volume covered by the piston 5.

 The dissipated heating power therefore affects a volume of material the smaller the closer one is to outlet 6, so that despite the importance of the volume of material contained in the barrel, the flow of softened material through the outlet 6 can be obtained very quickly, at least as quickly as in the devices of the prior art working on loaves of material of only 10 kg.

 The material ejected from the outlet 6 is pushed by the gear pump 11 into the conduit 7. The pressure exerted by this pump 11 and the heating of the conduit 7 further improve the preparation of the material 1. The material thus prepared is then introduced into the extruder or an equivalent device responsible for delivering the calibrated cord.

 The piston 5 can in certain cases constitute only one element of a wall of the tank 2.

 In reinforcement of the jacks 13 or 14 or in their place we can provide weights on the piston 5 or a piston of significant weight, insofar as the said piston is designed to move up and down.

Thus with the device described above, it is possible to obtain a high flow rate of a material, for example based on butyl rubber, initially thick and hard with a low energy expenditure, lower than that required by the prior devices.
More precisely to deliver a material having a hardness
Shore of 70.0, with the previous devices it was necessary to expend an energy of about 20 kW to obtain 0.5 1 of material per minute while with the device of the invention only 10 kW is sufficient to obtain a flow rate of the order 1.5 to 3 1 per minute.

 These figures were obtained without the need to heat tank 2 externally.

 Of course, these figures are only non-limiting examples.

 In the same way the hardness of 70 advanced is only one example; harder materials of the order of 80 ° C. or even more can also be distributed and a fortiori less hard materials;

Claims (12)

 1. Method for extracting from a large reserve of material of high viscosity, in particular an elastomer of the butyl rubber type, of the heated material of lower viscosity, for example to supply a working machine with said material, in particular a extruder to form a cord intended to serve as an interlayer between two consecutive sheets of glass in multiple glazing, characterized in that a limited volume of high viscosity material is reheated, a volume whose section is all the more reduced as it is more near an outlet through which the heated material is extracted thanks to a pressure exerted on the heated volume.  2. Method according to claim 1, characterized in that the pressure is exerted against the direction of the extraction direction.  3. Device for implementing the method according to claim 1 or 2, characterized in that it comprises a heating piston 5 equipped with a material outlet, intended to be applied with pressure against the high viscosity material contained in a tank 2, this piston having a shape such that it delimits a volume of material the section of which is all the more reduced the closer it is to the outlet, this piston having on its face in contact with the material, appendages heaters which immerse in said material.  4. Device according to claim 3, characterized in that the reservoir is a barrel on which the piston is applied.  5. Device according to claim 4, characterized in that the piston has a conical surface.  6. Device according to claim 5, characterized in that the piston is conical or pyramid depending on whether the barrel is cylindrical or prismatic.  7. Device according to claim 6, characterized in that the piston has the shape of the surface of a circular base cone.  8. Salt device # on one of claims 3 to 7, characterized in that the appendages are included inside the volume delimited by the piston.  9. Device according to claim 8, characterized in that the appendages are directed along the axis of the piston.  10. Device according to one of claims 3 to 9 characterized in that the wall of the reservoir opposite the piston has a shape complementary to that of the piston.  11. Device according to one of claims 3 to 10, character ized in that the entire device is heated.  12. Application of the method and the device to the distribution of a plastic material having a Shore hardness which can be as high as about 70 or 800.