Chute for weighing a rubber mixture

Abstract

The invention relates to a weighing chute (10), the weighing chute (10) comprising a stationary main frame (18), a movable sub-frame (20), a receiving hopper (14) for receiving a mixture to be weighed fixedly mounted on the sub-frame, and weighing sensors (22), vibration dampers (30) being inserted between the main frame and the sub-frame, and the weighing sensors being movably mounted with respect to the main frame between an inoperative position in which the sub-frame and the receiving hopper rest on the vibration dampers and do not rest on the weighing sensors, and a weighing position in which the sub-frame and the receiving hopper rest on the weighing sensors and do not rest on the vibration dampers.

Description

CHUTE FOR WEIGHING A RUBBER MIXTURE

[0001] The present invention relates to the weighing of a rubber mixture, in particular at the outlet of an internal mixer.

[0002] In the manufacturing of tires, different rubber mixtures are made in internal mixers from different products: carbon black, natural and / or synthetic rubber, chemicals, oils, etc.

[0003] If the various mixed products are weighed or dosed upstream of the internal mixer, it is also necessary to weigh the mixture at the outlet of the internal mixer to check the weighing and dosing carried out upstream and to ensure that no mixture remains in the internal mixer.

[0004] Document CN 104441297 describes a weighing chute suitable for placement under an internal mixer.

[0005] A first drawback of the solution presented in this document CN 104441297 lies in the fixing of the frame 2 of the weighing chute under an internal mixer via fixing flanges 1. In fact, an internal mixer generates vibrations likely to interfere with the measurements carried out by the weighing sensors of the weighing chute.

[0006] According to another disadvantage of the solution presented in document CN 104441297, by being suspended from the internal mixer, the weighing chute and its frame 2 can also transmit vibrations or shocks to the internal mixer when the mixture falls from the internal mixer to the weighing chute. This transmission of vibrations or shocks from the weighing chute to the internal mixer is not desirable because it can gradually damage the fixing of the internal mixer to its own frame or certain components of the mixer.

[0007] Document CN 104441297 provides for the installation of rubber seals to attenuate the transmission of vibrations between the mixer and the weighing chute. However, given the mass of the mixtures to be weighed, a few hundred kilograms, and the mass of the weighing chute and its frame, several hundred kilograms, these simple rubber seals are not sufficient to quickly and effectively attenuate vibrations. In addition, such seals do not fully absorb the shock and significant kinetic energy generated by the fall of a mixture weighing a few hundred kilograms into the weighing chute.Also, in the solution presented in document CN 104441297, it is the jacks 5 provided between the chassis 2 and the mixing receptacle 6 which must absorb this kinetic energy each time a new mixture is dropped, whereas these actuators are generally not designed to withstand such repeated shocks and they risk being damaged very quickly with such use.

[0008] Document CN 104441297 also provides for inserting vibration absorbers 4 between the mixture receptacle 6 and the weighing sensors 3. However, these vibration absorbers 4 are not useful when the mixture falls into the receptacle 6 because, at that moment, the receptacle rests on the jacks 5 and not on the weighing sensors.

[0009] The present invention aims to remedy the drawbacks of the prior art by proposing an arrangement of a weighing chute offering better management of vibrations and shocks that may be generated during the use of such a weighing chute, for example for weighing a rubber mixture falling from an internal mixer. At the same time, the invention also aims to provide a weighing solution that offers better weighing performance, in particular in terms of time required for weighing, weighing resolution, and reliability and repeatability of measurements.

[0010] To this end, the invention relates to a weighing chute for weighing a mixture, in particular a rubber mixture, for example one coming from an internal mixer, the weighing chute comprising a fixed main chassis, a mobile secondary chassis, a hopper for receiving a mixture to be weighed, fixedly mounted on the secondary chassis, and weighing sensors.

[0011] According to the invention, vibration dampers are interposed between the main frame and the secondary frame, and the weighing sensors are mounted to be movable relative to the main frame between a rest position in which the secondary frame and the receiving hopper rest on the vibration dampers and do not rest on the weighing sensors, and a weighing position in which the secondary frame and the receiving hopper rest on the weighing sensors and do not rest on the vibration dampers.

[0012] In the weighing chute according to the invention, the vibration dampers are devices dedicated to absorbing shocks and vibrations. These dampers do not have a lifting function likely to be damaged by the repetition of shocks and vibrations due to the reception of a product weighing several hundred kilograms such as a rubber mixture intended for the manufacture of tires.

[0013] Advantageously but not necessarily, the invention may also provide that: - the weighing sensors are mounted on a raising and lowering device mounted on the main chassis, the raising and lowering device allowing the weighing sensors to be moved from their rest position to their weighing position, and from their weighing position to their rest position, - the lifting and lowering device allows the weighing sensors to be moved so that the weighing position of the weighing sensors is above their rest position, - the weighing sensors are located above the vibration dampers when these weighing sensors are in their weighing position, - more precisely, the weighing surfaces of the weighing sensors are located above the receiving surfaces of the vibration dampers when these weighing sensors are in their weighing position, - the weighing chute includes a device for monitoring the measurements taken by the weighing sensors, - the control device comprises means for applying a predetermined force to the secondary chassis when the weighing sensors are in their weighing position.

[0014] The invention also relates to an installation for producing a rubber mixture, for example in a tire manufacturing plant, comprising an internal mixer for producing a rubber mixture and a weighing chute according to the invention and located under this internal mixer for weighing the mixture produced by the mixer. Advantageously, the main frame of the weighing chute is independent of the frame on which the internal mixer is mounted.

[0015] Other characteristics and advantages of the invention will appear in the description which follows. This description, given by way of example and not as a limitation, refers to the schematic drawings attached in the appendix and in which: - figure 1 illustrates the reception of a product to be weighed in a weighing chute according to the invention, - figure 2 illustrates the weighing of a product to be weighed with a weighing chute according to the invention, - figure 3 illustrates the unloading of the product after weighing with a weighing chute according to the invention, - figure 4 illustrates the configuration for receiving a product to be weighed from a weighing chute according to the invention, - figure 5 illustrates a step of checking the absence of product to be weighed in a weighing chute according to the invention, - figure 6 illustrates a step of verifying the measurements carried out by the weighing sensors of a weighing chute according to the invention.

[0016] The invention relates to a weighing chute particularly intended for weighing rubber mixtures produced by internal mixers. In the context of this use, and as illustrated in FIG. 1, the weighing chute 10 is preferably arranged under the internal mixer 12 which produces the mixture to be weighed. In more detail, the weighing chute 10 comprising a receiving hopper 14 for a mixture to be weighed and the internal mixer 12 comprising an outlet 16 for discharging the mixture, the receiving hopper 14 is positioned under the discharge outlet 16 of the internal mixer.

[0017] The weighing chute 10 according to the invention comprises a fixed main frame 18, a movable secondary frame 20, and weighing sensors 22. The receiving hopper 14 for a mixture to be weighed is fixedly mounted on the secondary frame 20.

[0018] In order to avoid the transmission of vibrations or shocks between the internal mixer 12 and the weighing chute 10, the main frame 18 of the weighing chute is independent of the frame 24 on which the internal mixer is mounted.

[0019] For receiving a mixture M under an internal mixer, the receiving hopper 14 is open at the top. This receiving hopper 14 is for example parallelepiped and comprises side walls 26 forming a parallelepiped. The lower part of the hopper 14 can be closed to receive the mixture M to be weighed or open to evacuate the mixture M after weighing. For this purpose, the receiving hopper 14 preferably comprises at the bottom two doors P1, P2 arranged in an opposing manner and mounted to be able to rotate relative to the side walls 26 of the chute. For example, these doors P1, P2 are rotated by cylinders 28. For example, the cylinders 28 for actuating the doors are pneumatic to promote the speed of opening / closing and locking / unlocking of the doors P1, P2, and to allow the shock to be absorbed when a mixture falls onto the closed doors P1, P2.

[0020] To limit the mass of the receiving hopper 14, the side walls 26 of the hopper are for example made of an aluminum-based alloy. By limiting the hopper mass, it is possible to use weighing sensors 22 with better resolution or sensitivity and therefore offering better measurement accuracy. However, for reasons of mechanical resistance to shocks generated by the repeated falling of the mixtures M into the hopper 14, the doors P1, P2 are preferably made of steel.

[0021] Advantageously, the actuators 28 for actuating the doors P1, P2 and the doors P1, P2 make it possible to absorb part of the kinetic energy transmitted to the secondary chassis and to the main chassis of the chute when a mixture M falls into the receiving hopper 14.

[0022] According to the invention and to best absorb the vibrations and shocks that can be transmitted between the internal mixer and the weighing chute, vibration dampers 30 are interposed between the main chassis 18 and the secondary chassis 20 on which the receiving hopper 14 is mounted.

[0023] The vibration dampers 30 are preferably viscoelastic fluid dampers, for example made from a silicone elastomer. These dampers 30 do not provide a lifting function and do not require any mechanical return spring or additional return gas. Thanks to their viscoelastic fluid design, these dampers completely absorb the energy released by the shock of a mixture falling into the hopper and they quickly and effectively reduce the vibrations and their propagation to the main frame 18 of the chute. For example, the vibration dampers 30 are dampers from the BC1N range sold by the company ENIDINE ®.

[0024] The hopper 14 being for example parallelepiped, the weighing chute 10 comprises four vibration dampers 30, one at each lower corner of the receiving hopper 14.

[0025] Still according to the invention, the weighing sensors 22 are mounted to move relative to the main chassis 18 of the chute between a rest position, illustrated in FIG. 1, in which the secondary chassis 20 and the receiving hopper 14 rest on the vibration dampers 30 and do not rest on the weighing sensors 22, and a weighing position, illustrated in FIG. 2, in which the secondary chassis 20 and the receiving hopper 14 rest on the weighing sensors 22 and do not rest on the vibration dampers 30.

[0026] For their mobility relative to the main frame 18 of the chute, the weighing sensors 22 are for example mounted on a raising and lowering device 32 mounted on the main frame 18, the raising and lowering device 32 making it possible to take the weighing sensors 22 from their rest position to their weighing position, and from their weighing position to their rest position. For example, the raising and lowering device 32 comprises eccentrics 34 mounted to move in rotation relative to the main frame 18 and a platform 36 mounted on the eccentrics 34 and on which the weighing sensors 22 are mounted. For example, the eccentrics 34 are driven in rotation by an electric motor via a transmission by pulleys and belts (not shown).The eccentrics 34 make it possible to drive the platform 36 in a combined rotational and translational movement which makes it possible to increase or reduce the relative height of the weighing sensors 22 with respect to the main chassis 18. More generally, the raising and lowering device 32 makes it possible to move the weighing sensors 22 so that the weighing position of the weighing sensors is above their rest position.

[0027] According to the invention, in the weighing position of the weighing sensors, the receiving hopper 14 and the secondary frame 20 rest solely on the weighing sensors. For this purpose, the weighing sensors 22 are located above the vibration dampers 30 when these weighing sensors are in their weighing position. More precisely, the weighing surfaces 38 of the weighing sensors are located above the receiving surfaces 40 of the vibration dampers when these weighing sensors 22 are in their weighing position.

[0028] The hopper 14 being for example parallelepipedal, the weighing chute 10 comprises four weighing sensors 22, one at each lower corner of the receiving hopper 14. For For example, the weighing chute 22 comprises two raising and lowering devices 32 arranged on either side of the hopper 14, two weighing sensors 22 being mounted on the platform 36 of each raising and lowering device 32.

[0029] For example, the load cells 22 offer a resolution of 6000 points corresponding to a measurement interval of approximately 20 g. Preferably, the load cells are bending sensors. For example, these load cells comprise a double embedded beam working in bending and whose deformation is measured by gauges mounted in a Wheatstone bridge and whose imbalance is proportional to the load to be measured.

[0030] Once weighed by the weighing sensors 22, the mixture M is for example evacuated via an evacuation device 42 positioned under the weighing chute 10, and more precisely under the doors P1, P2 of the weighing chute, as illustrated in FIG. 3. During this evacuation of the mixture M and as during the reception of the mixture M, the reception hopper 14 rests on the vibration dampers 30. Optionally, the evacuation device 42 can be a device for shaping the mixture M, such as a calender or an extruder.

[0031] According to the invention, the method for weighing a mixture M carried out with the weighing chute 10 comprises the following steps, respectively illustrated by figures 1 to 4: - reception of the mixture M in the reception hopper 14, the hopper 14 and the secondary chassis 20 resting on the vibration dampers 30, and the doors P1, P2 of the hopper being closed, - implementation of the raising and lowering device(s) 32 so that the hopper 14 containing the mixture M and the secondary chassis 20 rest on the weighing sensors only, the doors P1, P2 of the hopper always being closed, and implementation of the weighing by the weighing sensors 22, - implementation of the raising and lowering device(s) 32 so that the hopper 14 containing the mixture M and the secondary chassis 20 no longer rest on the weighing sensors 22 but on the vibration dampers 30, and opening of the doors P1, P2 of the receiving hopper 14 so as to evacuate the weighed mixture M towards the evacuation device 42, - closing of the doors P1, P2 of the receiving hopper 14 so as to allow the reception of a new mixture M to be weighed, the hopper 14 and the secondary chassis 20 still resting on the vibration dampers 30.

[0032] Advantageously, the weighing method may also comprise an additional step of weighing the empty hopper after evacuation of the weighed mixture M and before receiving a new mixture M to be weighed. This step, illustrated in FIG. 5, aims in particular to check that no mixture remains in the hopper 14. For the implementation of this additional step, the raising and lowering device(s) 32 are implemented in such a way that the empty hopper 14 and the secondary chassis 20 rest on the weighing sensors 22 only.

[0033] In parallel with this control step or according to a predetermined frequency, corresponding for example to several measurement cycles of different successive mixtures, the weighing method can also comprise a step of verifying the measurements made by the weighing sensors of the weighing chute 10 according to the invention. For this purpose, and as illustrated in FIG. 6, the weighing chute 10 can comprise a device 44 for controlling the measurements made by the weighing sensors. For example, this control device 44 comprises means 46 for applying a predetermined force F to the secondary chassis 20 when the weighing sensors 22 are in their weighing position. These means 46 for applying a force F take for example the form of weights 48 which can be secured or detached of the secondary chassis 20 by an actuation system 50. For example, the chassis 20 comprises connecting arms 52 from which the weights 48 are suspended only when the actuation system 50 allows it. For example, an actuation system 50 is a support plate 54 moved in vertical translation by a motorized screw drive. The support plate 54 supports the weight(s) 48 to detach them from the secondary chassis 20 and no longer supports the weight(s) 48 to secure them to the secondary chassis 20. For example, two weights 48 are provided on either side of the receiving hopper 14, two weights 48 being able to be secured or detached from the secondary chassis 20 by the same actuation system 50.These weights 48, when they are supported by the secondary chassis 20 and this secondary chassis 20 and the receiving hopper 14 rest on the weighing sensors 22, make it possible to apply a known force F to the weighing sensors, via the secondary chassis 20, and thus to verify their measurement accuracy.

[0034] Finally, the invention also relates to an installation for producing a rubber mixture, for example in a tire manufacturing plant, comprising an internal mixer 12 for producing a rubber mixture and a weighing chute 10 located under this internal mixer 12 for weighing a mixture M produced by the internal mixer.

Claims

Claims 1. Weighing chute (10) for weighing a mixture (M), in particular a rubber mixture, for example from an internal mixer, the weighing chute (10) comprising a fixed main frame (18), a movable secondary frame (20), a receiving hopper (14) for a mixture to be weighed, fixedly mounted on the secondary frame, and weighing sensors (22), the weighing chute being characterized in that vibration dampers (30) are interposed between the main frame and the secondary frame, and in that the weighing sensors are mounted to be movable relative to the main frame between a rest position in which the secondary frame and the receiving hopper rest on the vibration dampers and do not rest on the weighing sensors, and a weighing position in which the secondary frame and the receiving hopper rest on the weighing sensors and do not rest on the vibration dampers.

2. A weighing chute (10) according to claim 1, wherein the weighing sensors are mounted on a raising and lowering device (32) mounted on the main frame, the raising and lowering device enabling the weighing sensors to be moved from their rest position to their weighing position, and from their weighing position to their rest position.

3. Weighing chute (10) according to claim 2, wherein the raising and lowering device (32) makes it possible to move the weighing sensors (22) so that the weighing position of the weighing sensors is above their rest position.

4. A weighing chute (10) according to claim 3, wherein the weighing sensors are located above the vibration dampers when these weighing sensors are in their weighing position.

5. Weighing chute (10) according to claim 4, wherein the weighing surfaces (38) of the weighing sensors are located above the receiving surfaces (40) of the vibration dampers when these weighing sensors are in their weighing position.

6. Weighing chute (10) according to one of the preceding claims, comprising a device (44) for controlling the measurements carried out by the weighing sensors.

7. Weighing chute (10) according to claim 6, in which the control device comprises means (46) for applying a predetermined force to the secondary chassis when the weighing sensors are in their weighing position.

8. Installation for producing a rubber mixture, for example in a tire manufacturing plant, comprising an internal mixer (12) for producing a rubber mixture (M) and a weighing chute (10) according to one of the preceding claims and located under this internal mixer for weighing the mixture produced by the mixer.

9. Installation for producing a rubber mixture according to claim 8, in which the main frame (18) of the weighing chute is independent of the frame (24) on which the internal mixer is mounted.

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