Method and system for preparing a rubber mixture

Abstract

The invention relates to a method for preparing a rubber mixture (3), comprising the steps of: mixing the rubber mixture (3) in a first rubber mixer; processing the rubber mixture into a defined shape (15) in a shaping machine (1a); cooling the defined shape (15) of the rubber mixture (3) in a cooling device (5); cutting off one or more pieces (16) from the defined shape (15) of the rubber mixture (3); weighing a defined mass (17) of the one or more pieces (16) of the rubber mixture (3); pressing the defined mass (17) of the rubber mixture into a bale (13); and feeding the bale (13) into a second rubber mixer. The invention furthermore relates to a system for carrying out the method.

Description

[0001] P2023,0616 WO N June 28, 2024 - 1 - Description Method and arrangement for preparing a rubber mixture The present invention relates to a method and an arrangement for preparing rubber mixtures. In particular, the use of anti-adhesion agents in so-called batch-off systems during rubber processing poses a significant problem, since anti-adhesion agents are associated with a multitude of disadvantages and risks. Such anti-adhesion agents are, for example, a dispersion of zinc stearate or magnesium stearate. These challenges include, among other things, the precise monitoring of the anti-adhesion agent concentration, which requires complex measuring technology and maintenance, as well as the contamination of the systems by dripping solution, which leads to deposits in the systems.The use of anti-adhesion agents can also impair product quality, as they are an unwanted foreign substance that is not part of the rubber formulation. Furthermore, uneven distribution during the application of the anti-adhesion agent can lead to excessive layer thicknesses and cause feed problems in subsequent mixing processes, as, for example, a lubricating film on the rotors and the material strips hinders feed into the mixing chambers. P2023,0616 WO N June 28, 2024 - 2 - Furthermore, there is a risk of the formation of harmful bacteria and foaming in the anti-adhesion agent film, which requires the use of additional chemicals. Another problem is the integration of strip cutters into the mixing process, as picking up a rubber strip and placing it on a strip cutter conveyor belt usually requires manual processes.Both the position and the shape of the strip are generally undefined, which makes automating the process difficult. One object of the present invention is to provide an improved preparation method and a corresponding arrangement. The present invention particularly relates to a method for preparing a rubber mixture. The method comprises at least the following steps: - mixing the rubber mixture in a first rubber mixer, - processing the rubber mixture in a shaping machine to a defined shape, - cooling the defined shape of the rubber mixture in a cooling device, - cutting one or more pieces from the defined shape of the rubber mixture, - weighing a defined mass of the one or more pieces of the rubber mixture, - pressing the defined mass of the rubber mixture into a bale, - adding the bale to a second rubber mixer. P2023,0616 WO N 28.June 2024 - 3 - The process can be repeated several times, for example, between a second and third or between a third and fourth, etc., rubber mixer. The process can be carried out repeatedly using the same arrangement or equipment or using different arrangements and equipment. Repeated mixing is particularly necessary to improve the mixing quality or to provide different mixing and ambient conditions for different mixing processes. In particular, vulcanization-inducing chemicals, for example, are often only added during the second or third mixing run. In the first step, the rubber compound is transferred from the first rubber mixer to a forming machine, such as an extruder or a rolling mill.This can be a sub-machine of the rubber mixer, arranged below the rubber mixer so that the rubber mixture can be ejected from the mixing chamber into the shaping machine. For example, the rubber mixture is formed into a suitable, manageable shape in the shaping machine for removal and further processing. The rubber mixture is preferably removed from the shaping machine in the form of strips. "Strips" means that the rubber mixture has a strip shape, i.e. the length of the surface of the formed molded body preferably significantly exceeds the width of the surface and a height perpendicular to the width and length of the strip is significantly smaller than the flat dimensions of the strip. Such strips are also referred to as skins in rubber processing.Pieces, especially sections of a defined length, can be easily cut from a strip and processed further. The comparatively low strips also have the advantage that the rubber material can be quickly cooled to a temperature close to ambient temperature through heat exchange with the environment, as the strip-shaped molded body of the rubber mixture then has a high surface-to-volume ratio. Due to the defined length of the sections, they can be easily handled by automation, which facilitates the automated production of bales of a specified size. For example, the defined length is up to one meter. The pieces are preferably transported automatically to a scale and weighed. The pieces can be stacked. It is preferable to place as many pieces on the scale until a defined mass is reached.For this purpose, pieces can be cut off and weighed until the defined mass is reached. Once the defined mass is reached, the conveyor belt can be stopped temporarily. It is also possible to increase the blade speed of the cutting device shortly before the weight is reached, thus achieving fine dosing. With a constant strip feed, the strips become smaller and the dosing becomes finer. In this way, for example, a tolerance of + / - 1% of the weight to be dosed can be achieved. Alternatively, it is also possible to cut off only a single, longer piece for the defined mass and to select the length so that the defined mass is achieved. The piece can, for example, be in the form of a long strip, which can be folded several times and arranged in several layers before pressing.Subsequently, the defined mass of the rubber mixture is pressed into a bale in a further step. The specified defined mass and the baler preferably also determine the maximum dimensions of the bale. The rubber bales are then transported, preferably automatically, to a feeding device of the second rubber mixer. The transport can be carried out, for example, by means of a conveyor belt, a driverless transport system, in particular a robot, but also, for example, by means of a forklift. Manual processes and activities can thus be largely or completely avoided. The process is easily automated, as the rubber mixture can be fed from the cooling device into a cutting device directly or via automated intermediate stations. In the cooling device, the rubber mixture is cooled, for example, to a predetermined temperature.For example, the rubber mixture is cooled to approximately room temperature. Cooling the rubber mixture P2023,0616 WO N June 28, 2024 - 6 - prevents any change in the material, for example due to thermal decomposition of the rubber components. Furthermore, the cooling reduces the stickiness of the rubber material. The cooling device is designed, for example, as a chamber of a batch-off system. Preferably, the rubber mixture is cooled until the rubber mixture has a desired stickiness and dimensional stability that does not hinder or facilitate handling of the rubber material, but still ensures good bonding of the rubber material into bales during pressing. Cooling can be passive or active, e.g., by air cooling using a fan or by immersion in a fluid, such as water.In particular, cooling can take place in a cooling device, especially a cooling system. The rubber mixture is preferably immersed in a water bath for cooling and then optionally dried, preferably air-dried. For example, the coolant is pure water or a water-alcohol mixture to avoid contamination of the rubber material with foreign substances. An active drying process prevents the accumulation of moisture in devices used during the process where moisture is undesirable. Drying with air can also serve for cooling. P2023,0616 WO N June 28, 2024 - 7 - To prevent the rubber material, which can, for example, have the shape of a flat strip, from sticking together during drying, the rubber material is preferably guided in a meandering pattern over appropriately arranged transport devices.Preferably, the rubber bale is free of anti-adhesion reagents when added to the second rubber mixer. This is achieved by the described process, in which the addition of anti-adhesion reagents is not required and therefore their addition can preferably be omitted. Rather, a certain stickiness of the rubber material is desired in order to form the described bales. Likewise, no intermediate steps are required, such as storage or transport steps, for which the stickiness of the rubber material must be further reduced. Preferably, the entire process is carried out automatically, which is made possible by carrying out the described steps in the specified order. Automation is achieved in particular by using suitable automated transport devices such as conveyor belts and robots between the individual processing devices.For example, no intermediate storage step is required between the ejection of the rubber material from the first rubber mixer and the addition of the rubber bale to the second rubber mixer. In particular, no intermediate storage step is required between the discharge from the cooling device and the weighing of the defined mass. The rubber material is transported and further processed directly from processing station to processing station, preferably in an automated manner. Unintentional sticking of the rubber material during storage is thus prevented. Alternatively, an intermediate storage step for the rubber bales can also be provided. All process steps described here and below are preferably always carried out in the described order, since the specified order ensures a process that is easy to automate.The present invention further relates to an arrangement for preparing a rubber mixture. In particular, the present invention relates to an arrangement for preparing the rubber mixture according to the method described above. Features described with regard to the arrangement can also apply to the method described above, and vice versa. The arrangement comprises at least a first rubber mixer, a shaping machine, a cooling device, a cutting device, a scale, a baler, a second rubber mixer, and transport devices between the individual devices. Preferably, said devices are arranged such that the rubber mixture passes through them in the stated order. The first rubber mixer comprises a mixing chamber in which the rubber mixture is mixed. The rubber mixture is ejected from the mixing chamber and subjected to a shaping P2023,0616 WO N 28.June 2024 - 9 - machine in the form of an extruder and / or rollers, for example, formed into a long, flat strip and automatically discharged onto a conveyor belt. From there, the rubber mixture is fed to the cooling device. Particularly when cooling with fluids or water, a drying device is preferably provided or arranged in which the rubber material is dried from the water or fluid, for example by a drying and / or cooling fan, and further cooled. From the cooling and drying device, the rubber material is then transported, preferably automatically, for example by means of a conveyor belt, to the cutting device. As previously described, the described arrangement or method thus allows the omission of anti-adhesion agents, which are an undesirable additive to the rubber material and can also be hazardous to health when handling the rubber material.The rubber material is drawn in the cooling device merely through a simple fluid, such as water or a water-alcohol mixture, for cooling purposes. The rubber material is automatically cut into smaller pieces on the conveyor belt by the cutting device, in particular a strip cutter, and transported to the scales, e.g., until a defined mass of rubber material is stored on the scales. For this purpose, the scales can, for example, comprise a suitable trough. The scales can be arranged directly behind the cutting device, so that, for example, the cut-off pieces from the strip cutter fall directly onto the scales. The rubber material, which is preferably in strip form, is preferably automatically deposited such that several layers of strips are arranged one above the other, thus forming a stack of rubber material.The rubber material is then automatically transported to a baling press, for example by tilting the trough, and pressed into a bale. Alternatively, the rubber material can also be pressed directly in the trough. The rubber material is then transported, preferably automatically, for example to a feeding device of the second rubber mixer. For example, the first rubber mixer and the second rubber mixer can also be the same rubber mixer. Preferably, the two rubber mixers are different rubber mixers. Transport to the feeding level is carried out, for example, by a robot, conveyor belt, or forklift. The bales are stored, for example, in transport compartments or on pallets with separating films. The separating films serve to prevent the bales from sticking to the transport device. The bales are automatically added to the feeding device.Further processing or weighing of the bales before or in the feeding device P2023,0616 WO N June 28, 2024 - 11 - is not necessary, so that the equipment expenditure on the feeding level can be reduced and space can be saved. The method and the arrangement are then described by way of example in a figure. The invention is not limited to the exemplary figure. Figure 1 shows a schematic representation of an exemplary arrangement and an exemplary method according to the present invention. Figure 1 shows an example of the arrangement according to the invention. The arrangement has a first rubber mixer 1 for mixing a rubber mixture 3 and a shaping machine 1a for processing the rubber mixture into a defined shape 15, in particular a strip shape. The arrangement has a conveyor belt 2 as a transport device for removing the rubber material 3 from the shaping machine 1a.The arrangement comprises a batch-off device 4, which comprises a cooling device 5 in the form of a dipping tank, a transport device 6, e.g., rollers, over which the rubber material 3 is guided in a meandering manner, and a drying and cooling fan 7 as a drying device. The entire batch-off device 4 can be regarded as a cooling device. P2023,0616 WO N June 28, 2024 - 12 - The dipping tank contains pure water or a water-alcohol mixture as a coolant, but no anti-adhesion agent. The arrangement comprises a cutting device 8 following the batch-off device 4, in particular a strip cutter, which cuts the strip-shaped rubber material 3 into pieces 16, in particular sections of a defined length. The arrangement comprises a scale 9 with a trough 10 in which the pieces 16 of the rubber material 3 are stacked and weighed up to a defined mass 17.The defined mass 17 is, for example, no more than 40 kg or no more than 35 kg and at least 25 kg or 30 kg, so that the bales 13 are well suited for feeding a rubber mixer. The arrangement comprises a baler 11 into which the defined mass 17 of rubber material 3 is automatically emptied from the scale and pressed into a bale 13. The bale 13 preferably has an approximately cuboid shape, with the dimensions of the bale 13 preferably being between 500x300x150 millimeters and 850x400x250 millimeters. Furthermore, the arrangement comprises a transport device 12 that transports the pressed bales 13 to the second rubber mixer 14. The method for preparing a rubber mixture 3 can be carried out by means of the arrangement. In the first rubber mixer 1, the rubber mixture 3 is mixed and then formed into a P2023,0616 WO N 28 in the forming machine 1a.June 2024 - 13 - processed into a defined shape 15, in particular into a strip. The strips are cooled in the batch-off device 4. Directly at the exit of the batch-off device 4, the strips are cut into pieces 16 by the cutting device 8. A defined mass 17 of the pieces 16 is weighed. For this purpose, the pieces 16 fall, for example, directly from the cutting device 8 into the trough 10, which stands on the scale 9. As soon as the desired mass is reached, the cutting device 8 can be stopped and the defined mass 17 is transported to the baling press 11 and pressed there into a bale 13. The bale 13 can then be fed into a second rubber mixer 14.

[0002] P2023,0616 WO N June 28, 2024 - 14 - List of reference symbols 1 first rubber mixer 1a shaping machine 2 conveyor belt 3 rubber material 4 batch-off device 5 cooling device 6 transport device 7 drying device 8 cutting device 9 scale 10 tub 11 baling press 12 transport device 13 bale 14 second rubber mixer 15 defined shape 16 pieces 17 defined mass

Claims

P2023,0616 WO N June 28, 2024 - 15 - Patent claims 1. A method for preparing a rubber mixture (3), comprising the steps of: - mixing the rubber mixture (3) in a first rubber mixer (1), - processing the rubber mixture (3) in a shaping machine (1a) to a defined shape (15), - cooling the defined shape (15) of the rubber mixture (3) in a cooling device (5), - cutting off one or more pieces (16) from the defined shape (15) of the rubber mixture (3), - weighing a defined mass (17) of the one or more pieces (16) of the rubber mixture (3), - pressing the defined mass (17) to a bale (13), - adding the bale (13) to a second rubber mixer (14).

2. The method according to claim 1, wherein the rubber mixture (3) is discharged from the molding machine (1a) in the form of strips.

3. The method according to claim 2, wherein the strips are cut into sections of a defined length. 4.Method according to one of the preceding claims, wherein the defined mass (17) contains a plurality of pieces (16).

5. Method according to one of claims 1 to 3, wherein the defined mass (17) contains only one piece (16). P2023,0616 WO N June 28, 2024 - 16 - 6. The method according to one of the preceding claims, wherein the rubber mixture (3) is cut without intermediate storage and without manual handling after passing through the cooling device (5).

7. The method according to one of the preceding claims, wherein, during weighing, further pieces (16) are cut off and weighed together until the defined mass (17) is reached.

8. The method according to one of the preceding claims, wherein, shortly before the defined mass (17) is reached, the size of the pieces (16) is reduced during cutting.

9. The method according to one of the preceding claims, wherein the rubber mixture (3) is immersed in a water bath for cooling and then air-dried.

10. The method according to one of the preceding claims, wherein the bale (13) is free of anti-adhesion reagents upon addition to the second rubber mixer (14).Method according to one of the preceding claims, wherein the entire process is carried out automatically without manual handling of the rubber mixture.

12. An arrangement for preparing a rubber mixture (3) according to the method of one of the preceding claims, comprising a first rubber mixer (1), a shaping machine (1a), a cooling device (5), a cutting device (8), a scale (9), a baling press (11), a second rubber mixer (14), and transport devices (2, 12) between the individual devices. P2023,0616 WO N June 28, 2024 - 17 - Devices, wherein said devices are designed to be passed through by a rubber mixture (3) in the said order.

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