Chute for weighing rubber mixture

Abstract

The invention relates to a weighing chute (10) comprising a fixed main frame (18), a movable sub-frame (20), a receiving hopper (14) for receiving a mixture to be weighed and fixedly mounted on the sub-frame, and a weighing sensor (22), a damper (30) interposed between the main frame and the sub-frame, the weighing sensor is movably mounted relative to the main frame between an inoperative position, in which the sub-frame and the receiving hopper rest on the shock absorber rather than on the weighing sensor, and a weighing position, in which the sub-frame and the receiving hopper rest on the weighing sensor rather than on the shock absorber.

Description

Technical Field

[0001] The present invention relates to the weighing of rubber mixtures, particularly rubber mixtures at the outlet of an internal mixer. Background Art

[0002] In tire manufacturing, various rubber mixtures are produced in an internal mixer from various products (carbon black, natural and / or synthetic rubber, chemicals, oils, etc.).

[0003] If the various mixing products are weighed or dispensed 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 dispensing performed upstream and to ensure that there is no mixture residue in the internal mixer.

[0004] Document CN 104441297 describes a weighing chute adapted to be placed under an internal mixer.

[0005] The first drawback of the solution disclosed in document CN 104441297 is that: the frame 2 of the weighing chute is connected to the underside of the internal mixer by means of a connecting flange 1. Specifically, the vibrations generated by the internal mixer may interfere with the measurements made by the weighing sensors of the weighing chute.

[0006] Another drawback of the solution disclosed in document CN 104441297 is that: since the weighing chute and its frame 2 are suspended from the internal mixer, when the mixture falls from the internal mixer towards the weighing chute, the weighing chute and its frame 2 may also transmit vibrations or shocks to the internal mixer. This transmission of vibrations or shocks from the weighing chute to the internal mixer is undesirable because it will gradually damage the connection between the internal mixer and its own frame or certain components of the internal mixer.

[0007] Document CN 104441297 proposes installing rubber seals to attenuate the vibration transmission between the internal mixer and the weighing chute. However, considering the weight of the mixture to be weighed (several hundred kilograms) and the weight of the weighing chute and its frame (several hundred kilograms), these simple rubber seals are not sufficient to quickly and effectively attenuate the vibrations. In addition, such seals cannot completely absorb the shocks and significant kinetic energy generated when a mixture weighing several hundred kilograms falls into the weighing chute. Moreover, in the solution proposed in document CN104441297, whenever a new mixture drops, the cylinder 5 provided between the frame 2 and the mixing container 6 must absorb this kinetic energy, and these actuators are generally not designed to withstand such repeated shocks and they are likely to be quickly damaged in such use.

[0008] Document CN 104441297 also proposes inserting shock absorbers 4 between the mixing container 6 and the weighing sensors 3. However, these shock absorbers 4 are useless when the mixture falls into the container 6 because at this time the container is resting on the cylinder 5 rather than on the weighing sensors. Summary of the Invention

[0009] The present invention aims to overcome the drawbacks of the prior art by proposing an arrangement of a weighing chute that can better manage the vibrations and shocks that may occur during the use of such a weighing chute (e.g., for weighing a rubber mixture falling from a mixer). At the same time, the present invention also aims to provide a weighing solution that offers better weighing performance, particularly in terms of the time required for weighing, the weighing resolution, and the reliability and repeatability of the measurement.

[0010] To this end, the present invention relates to a weighing chute for weighing a mixture (particularly a rubber mixture, e.g., a mixture from a mixer), the weighing chute comprising a fixed main frame, a movable sub-frame, a receiving hopper for receiving the mixture to be weighed and fixedly mounted on the sub-frame, and weighing sensors.

[0011] According to the present invention, shock absorbers are interposed between the main frame and the sub-frame, and the weighing sensors are movably mounted relative to the main frame between a rest position and a weighing position. In the rest position, the sub-frame and the receiving hopper rest on the shock absorbers rather than on the weighing sensors. In the weighing position, the sub-frame and the receiving hopper rest on the weighing sensors rather than on the shock absorbers.

[0012] In the weighing chute according to the present invention, the shock absorbers are devices dedicated to absorbing shocks and vibrations. These shock absorbers do not have a lifting function and may be damaged by the repeated shocks and vibrations caused by receiving products weighing hundreds of kilograms (e.g., a rubber mixture for manufacturing tires).

[0013] Advantageously, but not necessarily, the present invention can also provide:

[0014] - The weighing sensors are mounted on a lifting device mounted on the main frame, and the lifting device enables the weighing sensors to move from their rest position to their weighing position and from their weighing position to the rest position.

[0015] - The lifting device allows the weighing sensors to move such that the weighing position of the weighing sensors is higher than their rest position.

[0016] - When the weighing sensors are in their weighing position, these weighing sensors are located above the shock absorbers.

[0017] - More specifically, when the weighing sensors are in their weighing position, the weighing surfaces of these weighing sensors are located above the receiving surfaces of the shock absorbers.

[0018] - The weighing chute includes control means for checking the measurements made by the weighing sensors.

[0019] - The control device includes means for applying a predetermined force to the sub-frame when the load cell is in its weighing position.

[0020] The present invention also relates to an apparatus for producing a rubber mixture, for example in a tire manufacturing plant, comprising a mixer for producing the rubber mixture and a weighing chute according to the present invention, said weighing chute being located below the 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 mixer is mounted. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features and advantages of the present invention will become apparent from the following description. This specification is provided by way of non-limiting example and with reference to the accompanying schematic drawings, in which:

[0022] - Figure 1 depicts the reception of the product to be weighed in a weighing chute according to the present invention,

[0023] - Figure 2 depicts the weighing of the product to be weighed using a weighing chute according to the present invention,

[0024] - Figure 3 depicts the unloading of the product after weighing using a weighing chute according to the present invention,

[0025] - Figure 4 depicts the receiving configuration of the product to be weighed in a weighing chute according to the present invention,

[0026] - Figure 5 depicts the inspection step of the weighing chute according to the present invention without the product to be weighed,

[0027] - Figure 6 depicts the verification step of the measurement performed by the load cell of the weighing chute according to the present invention. DETAILED DESCRIPTION

[0028] The present invention relates to a weighing chute, particularly a weighing chute for weighing a rubber mixture produced by a mixer. In the context of this use, as Figure 1 shown, the weighing chute 10 is preferably arranged below the mixer 12 for producing the mixture to be weighed. More specifically, the weighing chute 10 includes a receiving hopper 14 for receiving the mixture to be weighed, and the mixer 12 includes an outlet 16 for discharging the mixture, and the receiving hopper 14 is located below the discharge outlet 16 of the mixer.

[0029] The weighing chute 10 according to the present invention includes a fixed main frame 18, a movable sub-frame 20, and a load cell 22. The receiving hopper 14 for receiving the mixture to be weighed is fixedly mounted on the sub-frame 20.

[0030] To prevent vibrations or shocks from being transmitted 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.

[0031] To receive the mixture M under the internal mixer, the top of the receiving hopper 14 is open. The receiving hopper 14 is, for example, in the shape of a parallelepiped and includes side walls 26 that form the parallelepiped. The bottom of the hopper 14 can be closed to receive the mixture M to be weighed or opened after weighing to discharge the mixture M. To this end, the receiving hopper 14 preferably includes at the bottom two doors P1, P2 that are arranged opposite each other and are rotatably mounted relative to the side walls 26 of the chute. For example, these doors P1, P2 are rotated by cylinders 28. For example, the door-actuating cylinders 28 are pneumatic to increase the speed of opening / closing and locking / unlocking of the doors P1, P2 and to enable them to absorb the shock when the mixture falls on the closed doors P1, P2.

[0032] To limit the mass of the receiving hopper 14, the side walls 26 of the hopper are made, for example, of an aluminum-based alloy. By limiting the mass of the hopper, load cells 22 with better resolution or sensitivity can be utilized, thus providing better measurement accuracy. However, to ensure mechanical resistance to the shocks generated by the repeated fall of the mixture M into the hopper 14, the doors P1, P2 are preferably made of steel.

[0033] Advantageously, when the mixture M falls into the receiving hopper 14, the door-actuating cylinders 28 of the doors P1, P2 and the doors P1, P2 are able to absorb some of the kinetic energy transmitted to the secondary frame and the main frame of the chute.

[0034] According to the invention, to best absorb the vibrations and shocks that may be transmitted between the internal mixer and the weighing chute, vibration dampers 30 are interposed between the main frame 18 and the secondary frame 20 on which the receiving hopper 14 is mounted.

[0035] The vibration dampers 30 are preferably viscoelastic dampers, for example made of silicone elastomers. These vibration dampers 30 do not provide a lifting function and do not require any mechanical return springs or additional return gases. Due to their viscoelastic design, these vibration dampers completely absorb the energy released by the shock of the 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 the BC1N series of vibration dampers sold by the company.

[0036] Since the hopper 14 is, for example, a parallelepiped, the weighing chute 10 includes four vibration dampers 30, one at each lower corner of the receiving hopper 14.

[0037] Still according to the invention, the load cells 22 are movably mounted relative to the main frame 18 of the chute in Figure 1 the stationary position shown andFigure 2 Between the weighing positions shown, in the rest position, the sub-frame 20 and the receiving hopper 14 rest on the shock absorbers 30 rather than on the load cells 22, and in the weighing position, the sub-frame 20 and the receiving hopper 14 rest on the load cells 22 rather than on the shock absorbers 30.

[0038] For the mobility relative to the main frame 18 of the chute, the load cells 22 are mounted, for example, on a lifting device 32 mounted on the main frame 18, the lifting device 32 enabling the load cells 22 to be moved from their rest position to their weighing position and from their weighing position to their rest position. For example, the lifting device 32 includes an eccentric wheel 34 rotatably mounted relative to the main frame 18 and a platform 36 mounted on the eccentric wheel 34, the load cells 22 being mounted on this platform 36. For example, the eccentric wheel 34 is rotated by an electric motor via a pulley and belt drive (not shown). The eccentric wheel 34 is capable of driving the platform 36 with a combined rotational and translational movement, which makes it possible to increase or decrease the relative height of the load cells 22 relative to the main frame 18. More generally, the lifting device 32 allows the load cells 22 to be moved such that the weighing position of the load cells is higher than their rest position.

[0039] According to the invention, in the weighing position of the load cells, the receiving hopper 14 and the sub-frame 20 rest only on the load cells. To this end, when these load cells are in their weighing position, the load cells 22 are located above the shock absorbers 30. More specifically, when these load cells 22 are in their weighing position, the weighing surface 38 of the load cells is located above the receiving surface 40 of the shock absorbers.

[0040] Since the hopper 14 is, for example, a parallelepiped, the weighing chute 10 includes four load cells 22, one at each lower corner of the receiving hopper 14. For example, the weighing chute 10 includes two lifting devices 32 arranged on both sides of the hopper 14, and two load cells 22 are mounted on the platform 36 of each lifting device 32.

[0041] For example, the load cells 22 provide 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 include bent double built-in beams, the deformation of which is measured by a meter mounted in a Wheatstone bridge, the imbalance of which is proportional to the load to be measured.

[0042] Once weighed by the load cells 22, the mixture M is discharged, for example, by a discharging device 42 located below the weighing chute 10 (more specifically, below the doors P1, P2 of the weighing chute), as Figure 3As shown. During the discharge of the mixture M, the receiving hopper 14 is rested on the shock absorber 30, just as during the reception of the mixture M. Optionally, the discharging device 42 may be a device for shaping the mixture M, such as a calender or an extruder.

[0043] According to the present invention, the method for weighing the mixture M using the weighing chute 10 comprises the following steps, as shown respectively Figures 1 to 4 as follows:

[0044] - Receiving the mixture M in the receiving hopper 14, the hopper 14 and the sub-frame 20 being rested on the shock absorber 30, and the doors P1, P2 of the hopper being closed,

[0045] - Actuating the lifting device 32 such that the hopper 14 containing the mixture M and the sub-frame 20 are rested only on the load cells, the doors P1, P2 of the hopper remaining closed, and weighing being carried out by means of the load cells 22,

[0046] - Actuating the lifting device 32 such that the hopper 14 containing the mixture M and the sub-frame 20 are no longer rested on the load cells 22 but on the shock absorber 30, and opening the doors P1, P2 of the receiving hopper 14 in order to discharge the weighed mixture M into the discharging device 42,

[0047] - Closing the doors P1, P2 of the receiving hopper 14 in order to allow the reception of a new mixture M to be weighed, the hopper 14 and the sub-frame 20 remaining rested on the shock absorber 30.

[0048] Advantageously, the weighing method may also comprise an additional step of weighing the empty hopper after discharging the weighed mixture M and before receiving the new mixture M to be weighed. As Figure 5 shown, this step is particularly intended to check that there is no residue of the mixture in the hopper 14. To carry out this additional step, the lifting device 32 is actuated such that the empty hopper 14 and the sub-frame 20 are rested only on the load cells 22.

[0049] In parallel with this control step or at a predetermined frequency (for example corresponding to several measurement cycles for different successive mixtures), the weighing method may also comprise a step of verifying the measurements carried out by the load cells of the weighing chute 10 according to the present invention. For this purpose, as Figure 6As shown, the weighing chute 10 may include a control device 44 for checking the measurements made by the load cells. For example, the control device 44 includes means 46 for applying a predetermined force F to the sub-frame 20 when the load cells 22 are in their weighing position. These means 46 for applying the force F are in the form of a counterweight 48, for example, which can be fixed to or removed from the sub-frame 20 by an actuation system 50. For example, the frame 20 includes a link arm 52 and the counterweight 48 is suspended from the link arm 52 only when the actuation system 50 permits. For example, the actuation system 50 is a support plate 54 that is vertically translated by an electric screw drive. The support plate 54 supports the counterweight 48 to remove it from the sub-frame 20 and no longer supports the counterweight 48 to fix it to the sub-frame 20. For example, two counterweights 48 are provided on both sides of the receiving hopper 14 and the two counterweights 48 can be fixed to or removed from the sub-frame 20 by the same actuation system 50. When these counterweights 48 are supported by the sub-frame 20 and the sub-frame 20 and the receiving hopper 14 are resting on the load cells 22, the counterweights 48 can apply a known force F to the load cells through the sub-frame 20, thereby verifying their measurement accuracy.

[0050] Finally, the invention also relates to an apparatus 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 below the internal mixer 12 for weighing the mixture M produced by the internal mixer.

Claims

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

2. The weighing chute (10) according to claim 1, wherein, The weighing sensors are mounted on a lifting device (32) mounted on the main frame, the lifting device enabling the weighing sensors to move from their rest position to their weighing position and from their weighing position to their rest position.

3. The weighing chute (10) according to claim 2, wherein, The lifting device (32) allows the weighing sensors (22) to move such that the weighing position of the weighing sensors is higher than their rest position.

4. The weighing chute (10) according to claim 3, wherein, When the weighing sensors are in their weighing position, these weighing sensors are located above the shock absorbers.

5. The weighing chute (10) according to claim 4, wherein, When the weighing sensors are in their weighing position, the weighing surfaces (38) of these weighing sensors are located above the receiving surfaces (40) of the shock absorbers.

6. The weighing chute (10) according to any one of the preceding claims, comprising control means (44) for checking the measurements made by the weighing sensors.

7. The weighing chute (10) according to claim 6, wherein, The control means comprise means (46) for applying a predetermined force to the secondary frame when the weighing sensors are in their weighing position.

8. An apparatus for producing a rubber mixture, for example in a tyre manufacturing plant, comprising an internal mixer (12) for producing a rubber mixture (M) and a weighing chute (10) according to any one of the preceding claims, the weighing chute (10) being located below the internal mixer for weighing the mixture produced by the internal mixer.

9. The apparatus for producing a rubber mixture according to claim 8, wherein, 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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