WO2014198946A1

WO2014198946A1 - Extruder for treatment unit for plastics materials, and treatment unit comprising such an extruder

Info

Publication number: WO2014198946A1
Application number: PCT/EP2014/062465
Authority: WO
Inventors: Carolina MARCHANTE
Original assignee: Marchante Carolina
Priority date: 2013-06-14
Filing date: 2014-06-13
Publication date: 2014-12-18
Also published as: FR3006935A1; FR3006935B1

Abstract

Extruder (8) for a treatment unit (2) for plastics materials, the extruder comprising: an extrusion casing (61) delimiting an extrusion chamber (62) and having a first, upstream end portion (61a) and a second, downstream end portion (61b) longitudinally opposite the first, upstream end portion, a first feed opening (39) fluidically connected to the extrusion chamber and intended to be connected to a first feed device (4), and a second feed opening (49) fluidically connected to the extrusion chamber and intended to be connected to a second feed device (5), the extruder being characterized in that the first and second feed openings are disposed on the first, upstream end portion and are substantially opposite one another.

Description

Extruder for a plastics processing unit, and processing unit comprising such an extruder

The present invention relates to an extruder for a plastics processing unit, and a processing unit comprising such an extruder.

A plastics processing unit, and more particularly a plastics recycling unit, comprises, in a known manner, in particular:

a grinding device arranged to grind plastic material,

a first large volume stirring tank connected to the grinding device and arranged to vacuum stir the crushed plastic material coming from the grinding device;

a second agitating tank, of a volume smaller than that of the first stirring tank, connected to the first stirring tank and arranged for vacuum stirring the crushed plastic material coming from the first stirring tank,

an extruder arranged to be supplied with crushed plastic material from the second agitation tank,

an extrusion die disposed downstream of the extruder, and

- A cutting device, also called pelletizer or granulator, arranged to cut into pellets the extruded plastic material.

The cascade arrangement of the first and second agitation tanks of such a processing unit significantly reduces the production speed of the plastic granules, which affects the efficiency of the processing unit.

In addition, such a configuration of the first and second stirring tanks makes it difficult to control the residence time of the plastic material in each of the first and second stirring tanks, and thus the control of the operating parameters (in particular the parameters of pressure, speed and temperature) of the extruder. Such a disadvantage is detrimental to obtaining uniform granules having predetermined intrinsic characteristics, such as a predetermined intrinsic viscosity, at the outlet of a cutting device disposed downstream of the extruder. The present invention aims to remedy all or part of these disadvantages.

For this purpose, the present invention relates to an extruder for a plastics processing unit, the extruder comprising:

an extrusion casing delimiting an extrusion chamber and comprising a first upstream end portion and a second downstream end portion opposite longitudinally to the first upstream end portion;

a first feed opening fluidly connected to the extrusion chamber and intended to be connected to a first feed device, and

a second feed opening fluidly connected to the extrusion chamber and intended to be connected to a second feed device,

the extruder being characterized in that the first and second feed openings are disposed on the first upstream end portion and are substantially opposed to each other.

Such a configuration of the extruder enables the extruder to be fed synchronously from the first and second feeders. Such synchronized feeding of the extruder is more particularly retained when the plastic material to be recycled does not require a long drying time before its introduction into the extruder, which is for example the case of polypropylene and polyethylene

Such synchronized feeding of the extruder makes it possible to optimize the filling speed and the filling rate of the extruder, which makes it possible to increase the production rate of the extruder, and therefore the efficiency of a unit of the extruder. treatment comprising such an extruder.

Such a configuration of the extruder also makes it possible alternately to supply the extruder from the first and second feed devices. Such synchronized feeding of the extruder is more particularly retained when the plastic material to be recycled requires a long drying time before its introduction into the extruder, which is for example the case of polyester.

In such a case, the first and second feed devices are fed alternately with crushed plastic material, and the operating parameters (in particular the pressure, the temperature and the volume of plastic material) of the first feeder are kept substantially identical to those of the second feeder. These provisions make it possible to keep the feeding conditions of the extruder substantially constant, and thus to ensure a substantially constant pressure at the outlet of the extruder. This results in particular the easy obtaining of uniform granules and having predetermined intrinsic characteristics.

In addition, such alternating feeding of the extruder makes it possible to ensure a substantially continuous supply of the extruder, which makes it possible to increase the rate of production of the extruder, and therefore the yield of a processing unit comprising such an extruder.

According to one embodiment of the invention, the first and second feed openings arranged substantially facing one another.

According to one embodiment of the invention, the extruder comprises a discharge opening fluidly connected to the extrusion chamber and intended to be connected to an extrusion die, the discharge opening being arranged on the second downstream end portion.

According to one embodiment of the invention, one of the first and second feed devices is a screw feeder, which allows for example to feed the extruder with a powdery material so as to modify the properties of the plastic material introduced into the extruder via the other feeding device.

According to one embodiment of the invention, the first and second feed openings are disposed on either side of a vertical plane passing through the longitudinal axis of the extruder.

According to one embodiment of the invention, the first and second feed openings are oriented substantially horizontally, and preferably substantially radially.

According to one characteristic of the invention, the extrusion casing comprises a first lateral portion and a second lateral portion opposite to the first lateral portion, the first and second feed openings being respectively disposed on the first and second lateral portions.

According to one embodiment of the invention, the extruder comprises at least one endless screw disposed in the extrusion housing. The worm is advantageously arranged to move the plastic material introduced into the extrusion chamber to the discharge orifice.

The present invention further relates to a plastics processing unit comprising:

an extruder according to the invention,

a first feed device connected to the first feed opening and arranged to supply the extruder with a first material via the first feed opening, and

- A second supply device connected to the second feed opening and arranged to feed the extruder with a second material via the second feed opening.

According to one embodiment of the invention, the first feed device is arranged to feed the extruder with a first powdery or granular material.

According to one embodiment of the invention, the second feed device is arranged to feed the extruder with a second powdery or granular material.

The first material may for example be the same or different from the second material.

According to another embodiment of the invention, at least one of the first and second materials is a plastic material.

According to another embodiment of the invention, the first and second materials are plastics, which may for example be identical or different.

According to one embodiment of the invention, each of the first and second feed devices comprises a feed casing. The feed casing of each of the first and second feed devices is preferably stationary.

According to a characteristic of the invention, at least one of the first and second feed devices comprises stirring means arranged to stir the material contained in said feed device. Advantageously, each of the first and second feed devices comprises stirring means arranged to stir the material contained in said feed device.

According to one embodiment of the invention, the stirring means belonging to the at least or to each of the first and second devices feeders comprise at least one rotary stirring member. The at least one stirring member is preferably rotatably mounted about a substantially vertical axis of rotation.

According to one embodiment of the invention, at least one rotary stirring member comprises at least one cutting edge. Such a stirring member thus forms a rotary cutting member arranged to agitate the material contained in the corresponding feed device.

According to one embodiment of the invention, the processing unit comprises first rotational drive means arranged to drive in rotation the at least one stirring member of the first feed device, and second drive means. rotary drive arranged to rotate the at least one stirring member of the second feed device.

According to one characteristic of the invention, the processing unit comprises:

first closing means arranged between the first feed opening of the extruder and an outlet orifice provided on the first feed device, the first closing means being movable between an open position allowing the feeding the extruder via the first feeder, and a shutter position preventing feeding of the extruder via the first feeder, and

second closing means arranged between the second feed opening of the extruder and an outlet orifice provided on the second feed device, the second closing means being movable between an open position allowing the feeding the extruder via the second feeder, and a shutter position preventing feeding of the extruder via the second feeder.

According to one embodiment of the invention, the first and second shutter means respectively comprise first and second shutter valves. According to one embodiment of the invention, the first and second shut-off valves are respectively first and second shut-off solenoid valves.

According to a characteristic of the invention, the processing unit further comprises a vacuum pump connected to the first and second feed devices, the vacuum pump being arranged to generate a depression in the first and second feed devices, and preferably in the feed casings of the first and second feeding devices.

a first depressurization line fluidly connected, on the one hand, to the vacuum pump and, on the other hand, to a depressurization orifice provided on the first feed device,

a second depressurization line fluidly connected, on the one hand, to the vacuum pump and, on the other hand, to a depressurization orifice provided on the second feed device.

According to one embodiment of the invention, the processing unit comprises:

first closing means disposed on the first depressurization pipe, the first closing means being movable between a closed position in which the first closure means close the first depressurization pipe, and an opening position in which the first closure means closing means open the first depressurization pipe, and

second closing means disposed on the second depressurization pipe, the second closure means being movable between a closed position in which the second closure means close the second depressurization pipe, and an opening position in which the second closure means closing means open the second depressurization pipe.

According to one embodiment of the invention, the first and second closure means respectively comprise first and second closure valves. According to one embodiment of the invention, the first and second closing valves are respectively first and second closing solenoid valves.

According to one embodiment of the invention, the processing unit comprises a supply device arranged to contain plastic material, the supply device being connected to the first and second feed devices and being arranged to supply the first and second plastic feeders. According to one embodiment of the invention, the processing unit comprises:

a first supply circuit connected on the one hand to the supply device and on the other hand to an inlet port provided on the first supply device, and

a second supply circuit connected on the one hand to the supply device and on the other hand to an inlet port provided on the second supply device.

According to one embodiment of the invention, the first supply circuit is arranged to supply, for example by gravity, the first plastic supply device.

According to one embodiment of the invention, the second supply circuit is arranged to feed, for example by gravity, the second plastic feed device.

a first injection pipe connected to the first supply circuit and arranged to inject neutral gas into the first supply circuit, and

a second injection pipe connected to the second supply circuit and arranged to inject neutral gas into the second supply circuit.

According to one embodiment of the invention, the first and second injection lines are connected to at least one source of neutral gas.

According to one embodiment of the invention, the processing unit comprises:

upstream primary shut-off means and downstream primary closure means arranged on the first supply circuit, the upstream primary shut-off means being movable between a shut-off position in which the upstream primary shut-off means close off the first supply circuit, and an open position in which the upstream primary shut-off means open the first supply circuit, the downstream primary shut-off means being movable between a shut-off position in which the primary shutter down shut off the first power supply circuit, and an open position in which the downstream primary closure means open the first power supply circuit, and

upstream secondary shut-off means and downstream secondary closure means disposed on the second feed circuit, the upstream secondary closing means being movable between a shut-off position in which the upstream secondary shut-off means close off the second supply circuit, and an open position in which the upstream secondary closure means open the second supply circuit, the downstream secondary closure means being movable between a closed position in which the means for closing secondary shutoff down close the second supply circuit, and an open position in which the secondary secondary closure means open the second supply circuit.

According to one embodiment of the invention, the upstream primary closure means are offset relative to the primary downstream sealing means along the first supply circuit.

According to one embodiment of the invention, the upstream secondary closure means are offset with respect to the secondary downstream closure means along the second supply circuit.

According to one embodiment of the invention, the first injection pipe opens into the first supply circuit between the primary downstream and upstream sealing means.

According to one embodiment of the invention, the second injection pipe opens into the second supply circuit between the secondary downstream and upstream filling means.

According to one embodiment of the invention, the vacuum pump is connected to the supply device, and is arranged to generate a vacuum in the supply device.

According to one embodiment of the invention, the treatment unit comprises a third depressurization line fluidly connected on the one hand to the vacuum pump and on the other hand to a depressurization orifice provided on the supply device.

According to one embodiment of the invention, the processing unit comprises third closure means disposed on the third depressurization pipe, the third closure means being movable between a closed position in which the third means closing closure the third depressurization pipe, and an open position in which the third closure means open the third depressurization pipe.

According to one embodiment of the invention, the third closure means comprise a third closure valve. According to one embodiment of the invention, the third closure valve is a third closing solenoid valve.

According to one embodiment of the invention, the supply device comprises heating means arranged to heat the plastic material contained in the supply device.

These provisions make it possible to dry the plastic material contained in the supply device before its introduction into the extruder, and thus to reduce the moisture content of the plastic material contained in the supply device.

According to one embodiment of the invention, the heating means are arranged to heat the plastic material at a temperature below the melting temperature of said plastic material.

According to one embodiment of the invention, the heating means comprise at least one infrared radiation source.

According to one embodiment of the invention, the supply device comprises a fixed casing.

According to one embodiment of the invention, the at least one infrared radiation source is oriented towards a lower part of the casing of the supply device.

According to a characteristic of the invention, the supply device comprises an inlet orifice, an outlet orifice, and displacement means arranged to move the plastic material introduced into the supply device from the inlet orifice. in the direction of the outlet.

According to one embodiment of the invention, the displacement means comprise a drive shaft, at least one displacement member integral in rotation with the drive shaft, and rotational drive means arranged to drive in rotate the drive shaft. According to one embodiment of the invention, the displacement means are further arranged to agitate or mix the plastic material contained in the supply device.

According to one embodiment of the invention, the displacement member is a worm.

According to another embodiment of the invention, the displacement member has a generally helical shape.

According to one embodiment of the invention, the outlet of the supply device is connected to the first and second feed devices. Preferably, the outlet of the supply device is connected to the first and second supply circuits.

According to one embodiment of the invention, the inlet of the supply device opens into a first end portion of the fixed housing, and the outlet of the supply device opens into a second portion of the end of the fixed housing opposite longitudinally to the first end portion.

According to one embodiment of the invention, the processing unit comprises connecting means arranged to alternately connect the outlet orifice of the supply device with the first and second supply circuits.

According to one embodiment of the invention, the processing unit comprises transfer means arranged to transfer the plastic material flowing through the outlet orifice of the supply device alternately to the first and second devices of the invention. food.

According to one embodiment of the invention, the transfer means comprise a transfer reservoir comprising an inlet opening connected to the outlet orifice of the supply device, a first outlet opening connected to the first feed device. , a second outlet opening connected to the second feed device, and a worm screw disposed in the transfer tank, the worm being rotatable respectively in a first direction of rotation in which the plastic material contained in the reservoir transfer is moved towards the first outlet opening, and in a second direction of rotation, opposite to the first direction of rotation, in which the plastic material contained in the transfer tank is moved towards the second outlet opening.

According to one embodiment of the invention, the processing unit further comprises at least one conveyor arranged to feed uncrushed plastic at least one of the first and second feed devices. For example, the processing unit comprises a first and a second conveyor arranged to feed unmilled plastic respectively the first and second feed devices.

Anyway, the invention will be better understood from the description which follows with reference to the attached schematic drawing showing, by way of non-limiting example, an embodiment of this processing unit.

Figure 1 is a schematic view of a processing unit according to the invention.

Figure 2 is a sectional view of a supply device belonging to the processing unit of Figure 1.

Figure 3 is a partial perspective view of the processing unit of Figure 1.

Figures 1 to 3 show a processing unit 2 of plastics, and more particularly a recycling unit of plastics, especially polymers, such as polyester, polypropylene and polyethylene.

As shown in FIG. 1, the processing unit 2 comprises:

a supply device 3 intended to contain crushed plastic material,

a first and a second supply device 4, 5 connected to the supply device 3 via a first and a second supply circuit 6, 7, respectively, the first and second supply circuits 6, 7 being arranged to feed , for example by gravity, respectively the first and second feed devices 4, 5 crushed plastic material,

an extruder 8 connected to the first and second feeders 4, 5, and intended to feed a plastic extrusion die (not shown in the figures), and

a vacuum pump 9 connected to the supply device 3 and to the first and second feed devices 4, 5. As shown more particularly in Figures 2 and 3, the supply device 3 comprises a housing 10 defining a drying chamber January 1. The casing 10 is preferably fixed, and advantageously has a generally cylindrical shape.

The supply device 3 further comprises an inlet orifice 12 opening into the drying chamber 11, and arranged to introduce wet plastic material into the drying chamber January 1, and an outlet opening 13 opening into the drying chamber 1 1, and arranged to evacuate at least partially dried plastic material out of the drying chamber 1 1. The inlet port 12 is intended to be connected to a mill (not shown in the figures) disposed upstream of the supply device 3 so as to feed the drying chamber 1 1 crushed plastic material. The outlet orifice 13 is connected to the first and second supply circuits 6, 7, and is arranged to discharge the dried plastic material to the first and second supply circuits 6, 7.

The casing 10 comprises a first end portion 11a and a second end portion 11b opposite longitudinally to the first end portion 11a. According to the embodiment shown in Figure 2, the inlet port 12 is disposed on an upper portion of the first end portion 11a, and the outlet port 13 is disposed on a lower portion of the second end portion 1 1 b.

The supply device 3 also comprises a depressurization orifice 14 opening into the drying chamber 11, and fluidly connected to the vacuum pump 9 via a depressurization line 15. According to the embodiment shown in FIG. Depressurization port 14 is disposed on an upper portion of the second end portion 11b.

The supply device 3 further comprises a plurality of infrared radiation sources 16 disposed in the housing 10 and arranged to heat the plastic material M contained in the housing 10. The infrared radiation sources 16 are advantageously regularly spaced from each other . The sources of infrared radiation 16 are oriented towards a lower part of the drying chamber 11 so as to heat the plastic material M introduced into the drying chamber 11. The infrared radiation sources 16 are for example mounted on a support member 17 extending substantially parallel to the longitudinal axis of the housing 10.

The supply device 3 also comprises a displacement member 18 integral in rotation with a drive shaft 19 extending at least partly inside the housing 10. The drive shaft 19 extends from preferably substantially parallel to the longitudinal axis of the housing 10.

The displacement member 18 has a generally helical shape, and is rotatably mounted about its longitudinal axis. The displacement member 18 may for example be metallic.

According to the embodiment shown in Figure 2, the displacement member 18 is formed by a helical ribbon wound around a winding axis substantially parallel to the longitudinal axis of the housing 10. The winding axis is preferably coincides with the longitudinal axis of the housing 1 0. In addition, the displacement member 18 preferably extends at least partly around the support member 17.

The supply device 3 further comprises a drive motor 21 arranged to rotate the drive shaft 19 about its longitudinal axis. The displacement member 18 is arranged on the one hand to mix the plastic material introduced into the drying chamber 1 1, and on the other hand to move said plastic material towards the outlet orifice 13, when the shaft 19 is rotated by the drive motor 21.

As shown in FIG. 3, the processing unit 2 comprises a transfer tank 22 disposed downstream of the supply device 3. The transfer tank 22 comprises a housing 23 defining an interior volume, an inlet opening 24 connected at the outlet orifice 13 of the supply device 3 so as to supply the housing 23 made of dried plastic material, a first outlet opening 25 connected to the first supply circuit 6 and arranged to discharge the plastic material contained in the housing 23 to the first supply circuit 6, and a second outlet opening 26 connected to the second supply circuit 7 and arranged to discharge the plastic material contained in the housing 23 to the second supply circuit 7. The transfer reservoir 22 also comprises a worm 27 disposed in the housing 23. The worm 27 is rotatable respectively in a first direction of rotation in which the worm 27 moves the plastic contained in the housing 23 in the direction of the first outlet opening 25, and in a second direction of rotation opposite the first direction of rotation, in which the worm 27 moves the plastic material contained in the housing 23 towards the second outlet opening 26 .

The transfer reservoir 23 thus makes it possible, depending on the direction of rotation of the worm 27, to transfer the plastic material flowing through the outlet orifice 13 of the supply device 3 alternately to the first and second devices. supply 4, 5.

As shown in FIG. 1, the processing unit 2 comprises two shut-off valves 28, 29 arranged on the first supply circuit 6, the shut-off valve 28 being arranged upstream of the shut-off valve 29. Each of the shut-off valves 28, 29 is movable between a shut-off position in which said shut-off valve closes the first supply circuit 6, and an open position in which said shut-off valve opens the first circuit. 6. The shut-off valves 28, 29 make it possible to regulate, according to their position, the plastic feed of the first feed device 4.

The processing unit 2 also comprises two shut-off valves 31, 32 arranged on the second supply circuit 7, the shut-off valve 31 being arranged upstream of the shut-off valve 32. Each of the shut-off valves 31, 32 is movable between a closed position in which said shut-off valve closes the second supply circuit 7, and an open position in which said shut-off valve opens the second supply circuit 7. shut-off valves 31, 32 make it possible to regulate, according to their position, the plastic supply of the second supply device 5.

According to one embodiment of the invention, the shut-off valves 28, 29, 31, 32 are solenoid valves, and the processing unit comprises control means arranged to control the operation of these solenoid valves.

The processing unit 2 furthermore comprises a first injection pipe 33 connected to a source of neutral gas S, and arranged for injecting neutral gas in the first supply circuit 6, and a second injection line 34 connected to the source of neutral gas S, and arranged to inject neutral gas into the second supply circuit 7. According to an embodiment of the invention, the first and second injection pipes 33, 34 could be connected to two different sources of neutral gas.

The injection of neutral gas into the first and second supply circuits 6, 7 makes it possible to keep the moisture content of the plastic material coming from the supply device 3 and flowing towards the first and second devices feeding 4, 5.

According to the embodiment shown in the figures, the first injection pipe 33 opens into the first supply circuit 6 between the shut-off valves 28, 29, and the second injection pipe 34 opens into the second circuit d supply 7 between the shut-off valves 31, 32.

The processing unit 2 further comprises a closure valve 35 disposed on the depressurization line 15, the closure valve 35 being movable between a closed position in which the closure valve 35 closes the depressurization line 15, and a opening position in which the closing valve 35 opens the depressurization line 15.

Thus, the vacuum pump 9 is able to generate, depending on the position of the closure valve 35, a vacuum, with respect to the atmospheric pressure, in the supply device 3. The vacuum pump 9 is more particularly arranged to keep the supply device 3 under vacuum

According to one embodiment of the invention, the closure valve 35 is a solenoid valve, and the control means are arranged to control the operation of this solenoid valve.

It should be noted that the shut-off valves 28, 29 allow, according to their position, to ensure a transfer of plastic material to the first feeder 4 while maintaining the depressions present in the supply device 3 and the first feed device 4. Similarly, the shut-off valves 31, 32 allow, depending on their position, to ensure a transfer of plastic material to the second feed device 5 while maintaining the depressions present in the supply device 3 and the second supply device 5.

As shown in FIG. 1, the first feed device 4 comprises a housing 36 delimiting a stirring chamber, an inlet orifice 37 connected to the first feed circuit 6 and arranged to feed the plastic housing 36, an outlet orifice 38 connected to a first feed opening 39 provided on the extruder 8 and arranged to discharge the plastic material contained in the casing 36 to the extruder 8, and a depressurization orifice 41 fluidly connected to the pump vacuum 9 via a depressurization pipe 42. According to one embodiment of the invention, the housing 36 is fixed, and may for example have a generally cylindrical shape.

Preferably, the first feed device 4 further comprises a plurality of rotary stirring members 43 disposed within the housing 36 and each having at least one cutting edge, and the processing unit 2 comprises in addition to first rotary drive means arranged to rotate the stirring members 43, for example along a substantially vertical axis of rotation. The first rotary drive means comprise, for example, a drive motor 44 coupled in rotation to a support shaft 45 supporting the stirring members 43.

The first feed device 4 is arranged to feed the plastic extruder 8 via the outlet orifice 38 and the first feed opening 39. According to one embodiment of the invention, the plastic material is projected towards the the first feed opening 39 via the stirring members 43.

The second feed device 5 comprises a housing 46 defining a stirring chamber, an inlet orifice 47 connected to the second feed circuit 7 and arranged to feed the plastic housing 46, an outlet orifice 48 connected to a second feed opening 49 provided on the extruder 8 and arranged to discharge the plastic material contained in the casing 46 to the extruder 8, and a depressurization orifice 51 fluidly connected to the vacuum pump 9 via a depressurization pipe According to one embodiment of the invention, the housing 46 is fixed, and may for example have a generally cylindrical shape.

Preferably, the second feed device 5 further comprises a plurality of rotary stirring members 53 disposed within the housing 46 and each having at least one cutting edge, and the processing unit 2 further comprises second rotary drive means arranged to drive the stirring members 53 in rotation, for example along an axis of rotation substantially vertical. The second rotary drive means comprise, for example, a drive motor 54 rotatably coupled to a support shaft 55 supporting the stirring members 53.

The second feed device 5 is arranged to feed the plastic extruder 8 via the outlet orifice 48 and the second feed opening 49. According to one embodiment of the invention, the plastic material is projected towards the the second feed opening 49 via the stirring members 53.

The processing unit 2 further comprises a shut-off valve 56 disposed between the first feed opening 39 of the extruder 8 and the outlet orifice 38 of the first feed device 4, the shut-off valve 56. being movable between an open position allowing the plastic feed of the extruder 8 via the first feed device 4, and a shut-off position preventing the plastic feed of the extruder 8 via the first feeding device 4.

The processing unit 2 also comprises a shut-off valve 57 arranged between the second feed opening 49 of the extruder 8 and the outlet orifice 48 of the second feed device 5, the shut-off valve 57 being movable between an open position allowing the plastic feed of the extruder 8 via the second feed device 5, and a closed position preventing the plastic feed of the extruder 8 via the second device power supply 5.

The shut-off valves 56, 57 thus make it possible to regulate, according to their position, the plastic feed of the extruder 8.

According to one embodiment of the invention, the shut-off valves 56, 57 are solenoid valves, and the control means are arranged to control the operation of these solenoid valves.

The processing unit 2 further comprises two closing valves 58, 59 disposed respectively on the depressurization lines 42, 52. The closing valve 58 is movable between a closed position in which the closure valve 58 closes the control line. depressurization 42, and an open position in which the valve of closure 58 opens the depressurization line 42, while the closing valve 59 is movable between a closed position in which the closing valve 59 closes the depressurizing line 52, and an opening position in which the closing valve 59 opens the depressurization line 52.

Thus, the vacuum pump 9 is able to generate, depending on the position of the closing valves 58, 59, a vacuum, with respect to the atmospheric pressure, in the first and second feed devices 4, 5. The pump vacuum 9 is more particularly designed to maintain the first and second feed devices 4, 5 under vacuum.

According to one embodiment of the invention, the closing valves 58, 59 are solenoid valves, and the control means are arranged to control the operation of these solenoid valves.

According to the embodiment shown in FIG. 1, the extruder 8 comprises an extrusion casing 61 delimiting an extrusion chamber 62. The extrusion casing 61 comprises a first upstream end portion 61a and a second portion the downstream end end 61b longitudinally opposite the first upstream end portion 61a, the first and second feed openings 39, 49 being disposed on the first upstream end portion 61a. The terms upstream and downstream refer to the direction of flow of the material in the extrusion chamber 62. The extruder 8 further comprises an evacuation opening 65 fluidly connected to the extrusion chamber 62 and intended to be connected. to the extrusion die, the discharge opening 65 being disposed on the second downstream end portion 61b.

The first and second feed openings 39, 49 are arranged substantially facing one another, and are oriented substantially horizontally. Preferably, the first and second feed openings 39, 49 open respectively into first and second lateral portions 63, 64 of the casing 61 of the extruder 8.

According to one embodiment of the invention, the processing unit 2 may comprise a first and a second conveyor (not shown in the figures) arranged to feed unmilled plastic (for example sheets or pieces of film not crushed) respectively the first and second feeders 4, 5. As goes without saying, the invention is not limited to the sole embodiment of this processing unit, described above as an example, it encompasses all the variants.

Claims

1. Extruder (8) for processing unit (2) of plastics, the extruder comprising:

an extrusion casing (61) delimiting an extrusion chamber (62) and comprising a first upstream end portion (61a) and a second downstream end portion (61b) opposite longitudinally to the first portion; upstream end (61 a),

a first feed opening (39) fluidly connected to the extrusion chamber (62) and intended to be connected to a first feed device (4), and

a second feed opening (49) fluidly connected to the extrusion chamber (62) and intended to be connected to a second feed device (5),

the extruder being characterized in that the first and second feed openings (39, 49) are disposed on the first upstream end portion (61a) and are substantially opposite to each other.

2. Extruder according to claim 1, wherein the first and second feed openings (39, 49) are arranged substantially opposite one another.

An extruder according to claim 1 or 2, wherein the extrusion casing comprises a first lateral portion (63) and a second lateral portion (64) opposite to the first lateral portion (63), the first and second openings power supply (39, 49) being disposed respectively on the first and second side portions (63, 64).

4. Processing unit (2) of plastics, comprising:

an extruder (8) according to one of claims 1 to 3,

a first feed device (4) connected to the first feed opening (39) and arranged to feed the extruder (8) with a first material via the first feed opening (39), and - A second feed device (5) connected to the second feed opening (49) and arranged to feed the extruder (8) with a second material via the second feed opening (49).

5. Treatment unit (2) according to claim 4, wherein at least one of the first and second feed devices (4, 5) comprises stirring means.

6. Treatment unit (2) according to claim 5, wherein the stirring means comprise at least one rotary stirring member (43, 53).

7. Treatment unit (2) according to claim 6, wherein at least one rotary stirring member (43, 53) comprises at least one cutting edge.

8. Treatment unit (2) according to one of claims 4 to 7, which comprises:

first closure means (56) arranged between the first feed opening (39) of the extruder (8) and an outlet orifice (38) provided on the first feed device (4), the first shutter means being movable between an open position allowing feeding of the extruder (8) via the first feed device (4), and a shut-off position preventing feeding of the extruder (8). ) via the first feeder (4), and

second closing means (57) arranged between the second feed opening (49) of the extruder (8) and an outlet orifice (48) provided on the second feed device (5), the second shutter means being movable between an open position allowing feeding of the extruder (8) via the second feed devices (5), and a shut-off position preventing feeding of the extruder (8). ) via the second feed devices (5).

The processing unit (2) according to one of claims 4 to 8, which further comprises a vacuum pump (9) connected to the first and second feed devices (4, 5), the vacuum pump (9), ) being arranged for generating a depression in the first and second feed devices (4, 5).

10. Treatment unit (2) according to one of claims 4 to 9, which comprises a supply device (3) arranged to contain plastic material, the supply device (3) being connected to the first and second feeding devices (4, 5) and being arranged to supply the first and second plastic feed devices (4, 5).

1 1. Treatment unit (2) according to claim 10, which comprises:

- a first supply circuit (6) connected on the one hand to the supply device (3) and on the other hand to an inlet port (37) provided on the first supply device (4), and

- A second supply circuit (7) connected on the one hand to the supply device (3) and on the other hand to an inlet port (47) provided on the second feed device (5).

12. Treatment unit (2) according to claim 11, which comprises:

a first injection pipe (33) connected to the first supply circuit (6) and arranged to inject neutral gas into the first supply circuit (6), and

a second injection pipe (34) connected to the second supply circuit (7) arranged to inject neutral gas into the second supply circuit (7).

13. Treatment unit (2) according to claim 1 1 or 12, which comprises:

upstream primary closing means (28) and downstream primary closing means (29) arranged on the first feed circuit (6), the upstream primary closing means (28) being movable between a first position shutter in which the upstream primary shut-off means (28) close off the first feed circuit (6), and an open position in which the upstream primary shut-off means (28) open the first supply circuit (6), the downstream primary closing means (29) being movable between a closed position in which the downstream primary closing means (29) close off the first supply circuit (6), and an opening position in which the downstream primary closing means (29) opens the first supply circuit (6), and

upstream secondary closing means (31) and downstream secondary closing means (32) arranged on the second feed circuit (7), the upstream secondary closing means (31) being movable between a position of shutter in which the upstream secondary closing means (31) seal the second supply circuit (7), and an opening position in which the upstream secondary closing means (31) open the second supply circuit (7), the downstream secondary closing means (32) being movable between a closed position in which the downstream secondary closing means (32) seal the second supply circuit (7), and a position of opening in which the downstream secondary closing means (32) open the second supply circuit (7).

14. Treatment unit (2) according to one of claims 10 to 13 in combination with claim 9, wherein the vacuum pump (9) is connected to the supply device (3), and is arranged to generate a depression in the supply device (3).

15. Treatment unit (2) according to one of claims 10 to 14, wherein the supply device (3) comprises an inlet port

(12), an outlet (13), and displacement means arranged to move the plastic material introduced into the supply device (3) from the inlet port (12) towards the output (13).