Device for mixing a rubber mixture

Abstract

Device (100) for mixing a rubber mixture, comprising a mixing chamber (10) with a mixing chamber wall (15), a rotor (20) comprising a rotor body (22) which rotates in the mixing chamber (10), and a rotor shaft (25) which extends along a first longitudinal direction (L1) and penetrates an opening (16) of the mixing chamber wall (15). The device (100) further comprises a dust seal (30) suitable for sealing the mixing chamber (10), comprising an inner dust seal ring (31) arranged on the rotor (20), an outer dust seal ring (33) arranged on a first circumferential surface (17) of the opening (16), and a piston ring (50) arranged on a second circumferential surface (34) of the outer dust seal ring (33) and suitable for realizing a seal between the outer dust seal ring (33) and the first circumferential surface (17).

Description

[0001] The present disclosure relates to an apparatus for mixing rubber compounds.

[0002] An internal mixer is typically designed to produce a batch of mixtures through a series of processing steps. The processing steps include charging materials of different compositions, such as rubber or plastic, into a mixing chamber, kneading the materials by rotors located within the chamber, and discharging the mixture from the mixing chamber to the outside through a trapdoor after a certain amount of mixing. In such a mixer, the rotor shaft of the rotor is arranged to penetrate into the mixing chamber. Therefore, it is necessary to provide a leakage prevention means on the rotor shaft to prevent the contents of the mixing chamber from leaking out of the mixing chamber.

[0003] It is desirable to create a device for mixing rubber compounds which is easy to maintain, enables satisfactory sealing and reliable operation of the device with as few failures as possible.

[0004] According to one embodiment, a device for mixing a rubber mixture comprises a mixing chamber with a mixing chamber wall, a rotor comprising a rotor body that rotates in the mixing chamber, and a rotor shaft that extends along a first longitudinal direction and penetrates an opening in the mixing chamber wall. The device further comprises a dust seal suitable for sealing the mixing chamber, comprising an inner dust seal ring arranged on the rotor, an outer dust seal ring arranged on a first circumferential surface of the opening, and a piston ring arranged on a second circumferential surface of the outer dust seal ring, and suitable for realizing a seal between the outer dust seal ring and the first circumferential surface.

[0005] For example, two rotors are arranged side by side in the mixing chamber along a second longitudinal direction. The second longitudinal direction is oriented perpendicular to the first longitudinal direction. Alternatively or additionally, the rotors can also be arranged one above the other, perpendicular to the first longitudinal direction and the second longitudinal direction. The rotor body is designed to rotate in the mixing chamber and knead a mixture that is introduced into the mixing chamber. The device further comprises a dust seal, which is designed to seal the mixing chamber.

[0006] The dust seal of the device, for example, an internal mixer, comprises the inner dust seal ring and the outer dust seal ring. The inner dust seal ring is attached to the rotor, and the outer dust seal ring is recessed into the mixing chamber wall. In particular, the outer dust seal ring is arranged on the first circumferential surface of the opening in the mixing chamber wall. The dust seal is arranged at each of the openings where the rotor shaft penetrates the mixing chamber wall. For example, a mixing chamber comprises two rotors, each with a rotor shaft that penetrates two mixing chamber walls. Accordingly, the mixing chamber has four openings that must be sealed to prevent the mixture and / or dust from escaping from the mixing chamber.

[0007] The inner dust seal ring, for example, is designed in two parts. Specifically, the inner dust seal ring is formed from two circular ring sections that, when assembled, form a single ring. During initial assembly, the inner dust seal ring can be pulled onto the rotor shaft and connected to the rotor body. The connection between the inner dust seal ring and the rotor body is achieved, for example, by means of screws. During maintenance of the device, the inner dust seal ring must be designed in two parts when replacing it to ensure the easiest possible disassembly and to allow for simple reassembly.

[0008] The outer dust sealing ring, for example, is designed in at least two parts. In particular, the outer dust sealing ring is formed from two circular ring sections that, when assembled, form a single ring. During maintenance of the device, the outer dust sealing ring must be designed in at least two parts when replacing it to ensure the easiest possible removal and to allow for easy reassembly.

[0009] The dust seal further comprises the piston ring, which is arranged on the second circumferential surface of the outer dust sealing ring and is suitable for creating a seal between the outer dust sealing ring and the first circumferential surface. The piston ring is interrupted and can be pulled over the outer dust sealing ring. The piston ring is pulled over the outer dust sealing ring during initial assembly and fastened. During maintenance of the device, for example to change the dust sealing rings, the piston ring is only pulled off the outer dust sealing ring and remains in place on the rotor shaft. The piston ring can be manufactured to fit precisely before initial commissioning. This avoids, for example, the need to readjust the piston ring during subsequent maintenance.The friction between the first circumferential surface of the mixing chamber wall opening and the outer dust seal ring is defined and remains unchanged when a piston ring is used. This significantly simplifies the replacement of the dust seal rings. Since the seal between the outer dust seal ring and the first circumferential surface is realized by the piston ring, the seal needs to be replaced less frequently than, for example, an O-ring. This means that the piston ring can remain on the rotor shaft and does not need to be constructed in two parts, which reduces assembly effort. At the same time, re-adjusting the piston ring, i.e. the seal, is avoided. This has the advantage of making assembly less error-prone.

[0010] According to at least one embodiment, the device comprises a hydraulic cylinder which is suitable for pressing the outer dust sealing ring against the inner dust sealing ring along the first longitudinal direction in order to prevent the rubber mixture from escaping from the mixing chamber.

[0011] The outer dust seal ring is pressed against the inner dust seal ring using at least one hydraulic cylinder with a preset hydraulic pressure. Alternatively, more than one hydraulic cylinder is used per dust seal. This allows for a uniform contact pressure of the outer dust seal ring against the inner dust seal ring along its circumference.

[0012] According to at least one embodiment, a first end face of the inner dust sealing ring and / or a second end face of the outer dust sealing ring comprises hardened material or is formed from such a material.

[0013] The hardened material is, for example, hardened steel. The material of the two end faces is harder than the inner dust sealing ring and the outer dust sealing ring. The hardness of the material of the two end faces is preferably the same. The hardness of the material of the two end faces is, for example, in a range of 35 to 65 HRC (Rockwell hardness). The two end faces come into contact when the two dust sealing rings are pressed together. The inner dust sealing ring rests on the rotor body and is fastened to the rotor body, for example with screws, so that it can rotate together with the rotor body. The outer dust sealing ring is fixedly arranged on the first circumferential surface and does not rotate when the rotor shaft rotates. This creates friction and material wear between the first end face and the second end face.

[0014] According to at least one embodiment, the outer dust sealing ring comprises a first lubrication channel through which a lubricant is supplied to the second end face for lubrication between the inner dust sealing ring and the outer dust sealing ring.

[0015] At least one first lubrication channel is provided in the outer dust seal ring, through which a lubricant, such as oil, is forced onto the two end surfaces between the inner dust seal ring and the outer dust seal ring for lubrication. The number of first lubrication channels is not limited to a single one and can include a plurality of first lubrication channels. The amount of lubricant is adjustable.

[0016] According to at least one embodiment, the mixing chamber wall comprises a second lubrication channel through which a lubricant is guided to the side of the mixing chamber wall facing the rotor body.

[0017] This creates lubrication between the rotor body and the mixing chamber wall, binding any dust generated during mixing. The dust and lubricant form a pasty mass, preventing the dust from escaping from the mixing chamber. The lubricant can be oil, for example, and the amount of lubricant is adjustable.

[0018] According to at least one embodiment, the piston ring comprises hardened material or is formed from such a material.

[0019] In this context, hardened material is, for example, hardened steel. Due to the arrangement of the rotor body, an axial force acts on the rotor, particularly on the rotor shaft. This axial force causes an axial displacement of the rotor with each revolution within the scope of the axial play of the rotor shaft. The outer dust seal ring follows this axial movement, and thus also the installed piston ring. This leads to a load on the piston ring. By using hardened materials, the piston ring is less susceptible to friction and thus less wear, which leads to better sealing and a lower-maintenance device. The hardness of the piston ring material, for example, ranges from 20 to 50 HRC (Rockwell hardness).

[0020] According to at least one embodiment, the sealing between the outer dust sealing ring and the first circumferential surface is achieved by a plurality of piston rings.

[0021] According to at least one embodiment, the piston ring is arranged in a groove of the outer dust sealing ring.

[0022] It is possible to use a plurality of piston rings to improve the seal between the outer dust seal ring and the first circumferential surface of the opening in the mixing chamber wall. In particular, a plurality of piston rings can be arranged in the groove.

[0023] According to at least one embodiment, the outer dust sealing ring comprises a support part and a lining part facing the inner dust sealing ring.

[0024] The lining part is arranged along the first longitudinal axis between the inner dust sealing ring and the carrier part and rests against the inner dust sealing ring. The carrier part rests against the hydraulic cylinder. The carrier part is bolted to the lining part, for example.

[0025] When there is friction between the two dust sealing rings, the lining part is the first to wear out. This makes it possible to delay replacing the inner dust sealing ring. This is advantageous because the inner dust sealing ring is more difficult to disassemble due to its design. For this purpose, the lining part has a softer material than the first end face and / or the outer dust sealing ring or is made of such a material. Bronze or an alloy containing bronze, for example, is used as a softer material. By dividing the outer dust sealing ring into the lining part and the carrier part, only the lining part needs to be replaced when it wears out. In this way, the carrier part can also be designed as a one-piece ring, since replacing it and the associated complete detachment of the carrier part from the rotor shaft is avoided.The lining part, for example, is made of two sections so that it can be reassembled for maintenance even after initial installation. In particular, the lining part is formed from two circular ring sections that form a ring when assembled. Since the lining part is intended as a wear part and is designed to wear down in a targeted manner to protect the first end face from abrasion, there is no need to lubricate the first end face.

[0026] According to at least one embodiment, the groove is arranged on the carrier part and / or on the covering part.

[0027] During operation, not the entire lining part is worn, so the groove can be located on the lining part. The piston ring is therefore located in the groove on the lining part.

[0028] Alternatively, the groove is located on the carrier part. Accordingly, the piston ring is located in the groove on the carrier part. This has the advantage that there is no need to worry about the complete wear of the lining part. As a further alternative, the carrier part and the lining part each have a groove. A piston ring is located in each of the two grooves to improve the seal between the outer dust seal ring and the first circumferential surface. More than one piston ring can also be used per groove.

[0029] The invention is explained in more detail below with reference to figures.

[0030] They show: Fig. 1 is a schematic view of a device for mixing a rubber mixture, Fig. 2 a schematic representation of a section of a device according to an embodiment, Fig. 3 a schematic representation of a section of a device according to an embodiment, Fig. 4 a schematic representation of a section of a device according to an embodiment, Fig. 5 a schematic representation of a section of a device according to an embodiment, Fig. 6 a schematic representation of a section of a device according to an embodiment.

[0031] Fig. Figure 1 shows a schematic view of a device 100 for mixing a rubber mixture. The device 100 comprises a mixing chamber 10 with a mixing chamber wall 15. In Fig. 1, the mixing chamber 10 is shown as an example with four mixing chamber walls 15. The device 100 is not limited to four mixing chamber walls 15. Any number of mixing chamber walls 15 is possible, arranged to enclose a volume within the mixing chamber 10.

[0032] The device 100 further comprises a rotor 20 with a rotor body 22 and a rotor shaft 25. The rotor shaft 25 extends along a first longitudinal direction L1 and penetrates at least one opening 16 of the mixing chamber wall 15. In Fig. 1, one of the rotor shafts 25 penetrates two of the mixing chamber walls 15 at the respective openings 16. Alternatively, only one rotor 20 with a rotor body 22 and a rotor shaft 25 can be arranged in the device 100. Alternatively, more than two rotors 20 are arranged in the device 100, each comprising a rotor body 22 and a rotor shaft 25. For example, two rotors 20 are arranged next to one another in the mixing chamber 10 along a second longitudinal direction L2. The second longitudinal direction L2 is oriented perpendicular to the first longitudinal direction L1. The rotors 20 can alternatively or additionally also be arranged one above the other, perpendicular to the first longitudinal direction L1 and to the second longitudinal direction L2. The rotor body 22 is suitable for rotating in the mixing chamber 10 and for kneading a mixture that is admitted into the mixing chamber 10.

[0033] The device 100 further comprises a dust seal 30 which is suitable for sealing the mixing chamber 10. The dust seal 30 is shown in the view of Fig. 1 is arranged along the second longitudinal direction L2 between the rotor shaft 25 and a first circumferential surface 17 of the opening 16. The dust seal 30 extends along the first longitudinal direction L1 and circumferentially surrounds the rotor shaft 25. The device 100 comprises, for example, four dust seals 30, one of which is arranged in each of the four openings 16 in order to prevent or at least reduce the escape of the rubber mixture and / or dust generated in the mixing chamber 10 from the mixing chamber 10.

[0034] In the following, the Fig. 2 to 6, the invention is explained in more detail using a section of the device 100 which runs along a section axis AA.

[0035] Fig. Figure 2 shows a schematic representation of a section of the device 100 for mixing a rubber mixture. The section axis AA runs parallel to the longitudinal axis L1 and centrally through the rotational axis of the rotor 20 with the rotor shaft 25 and the rotor body 22. In Fig. 2, the mixing chamber 10 is shown as an example with a single mixing chamber wall 15. Arranged within the mixing chamber 10 is the rotor body 22, which is suitable for rotating in the mixing chamber 10 and for kneading a mixture that is introduced into the mixing chamber 10. The mixture is processed, for example, into a rubber mixture. The rotor shaft 25 extends along the first longitudinal direction L1 and penetrates the opening 16 of the mixing chamber wall 15. The device 100 further comprises the dust seal 30, which is suitable for sealing the mixing chamber 10. The illustration in Fig. 2 is provided for clarity and is not intended to be limiting. In this sense, the device 100 is not limited to a single mixing chamber wall 15, a single rotor 20, and a single dust seal 30.

[0036] The dust seal 30 comprises an inner dust seal ring 31, an outer dust seal ring 33, and a piston ring 50. The inner dust seal ring 31 is arranged on the rotor 20 and circumferentially surrounds the rotor shaft 25. The inner dust seal ring 31 is arranged, in particular, along the second longitudinal direction L2 between the rotor shaft 25 and the first circumferential surface 17 of the opening 16. The inner dust seal ring 31 bears against the rotor body 22 and is fastened to the rotor body 22, for example, with screws, so that it can rotate together with the rotor body 22.

[0037] The outer dust seal ring 33 is arranged at least partially along the second longitudinal direction L2 between the rotor shaft 25 and the first circumferential surface 17 and is recessed into the opening 16. The outer dust seal ring 33 is pressed against the inner dust seal ring 31 by at least one hydraulic cylinder 40 with a preset hydraulic pressure. More than one hydraulic cylinder 40 can also be used to uniformly press the outer dust seal ring 33. The inner dust seal ring 31 and the outer dust seal ring 33 comprise a first end face 32 and a second end face 35, respectively. The first end face 32 and / or the second end face 35 comprise a hardened material or are formed from such a material. The hardened material is, for example, hardened steel. The material of the end faces 32, 35 is harder than the inner dust seal ring 31 and the outer dust seal ring 33.The hardness of the material of the two end faces 32, 35 is preferably equally hard. For example, the hardness of the material of the two end faces 32, 35 is in a range of 35 to 65 HRC.

[0038] The two end faces 32, 35 come into contact when the two dust sealing rings 31, 33 are pressed together. The outer dust sealing ring 33 is fixedly arranged on the first circumferential surface 17 and does not rotate during a rotational movement of the rotor shaft 25. This results in friction and material wear between the first end face 32 and the second end face 35. In the outer dust sealing ring 33, at least one first lubrication channel 361 is provided, through which a lubricant, for example oil, is pressed onto the two end faces 32, 35 between the inner dust sealing ring 31 and the outer dust sealing ring 33 for lubrication. The number of first lubrication channels 361 is not limited to a single one and can comprise a plurality of first lubrication channels 361. The quantity of lubricant is adjustable.

[0039] The piston ring 50 is arranged on a second circumferential surface 34 of the outer dust sealing ring 33 and is suitable for creating a seal between the outer dust sealing ring 33 and the first circumferential surface 17 of the opening 16. The piston ring 50 is arranged, in particular, in a groove 39 of the outer dust sealing ring 33. The piston ring 50 comprises a hardened material or is formed from such a material. In this context, hardened material is, for example, hardened steel. The hardness of the material of the piston ring 50 is, for example, in a range of 20 to 50 HRC (Rockwell hardness). Due to the arrangement of the rotor body 25, an axial force acts on the rotor 20, in particular on the rotor shaft 25. This axial force causes an axial displacement of the rotor 20 with each revolution within the scope of the axial play of the rotor shaft 25.

[0040] The outer dust sealing ring 33 follows this axial movement and thus also the installed piston ring 50. This leads to a load on the piston ring 50. The use of hardened materials makes the piston ring 50 less susceptible to friction and thus less prone to wear, which leads to better sealing. When the dust sealing rings 31, 33 are replaced, the piston ring 50 can be pulled off the outer dust sealing ring 33 and remains on the rotor shaft 25 for further use. After the new dust sealing rings 31, 33 have been installed, the piston ring 50 is put back on. It is possible to place a plurality of piston rings 50 in the groove 39 in order to improve the seal between the outer dust sealing ring 33 and the first circumferential surface 17 of the opening 16 in the mixing chamber wall 15.

[0041] Fig. 3 shows a further embodiment of the device 100 in a schematic representation of a section of the device 100. The device 100 is the same as in Fig. 2, with the difference that a second lubrication channel 362 runs through the mixing chamber wall 15. The second lubrication channel 362 guides a lubricant to the side of the mixing chamber wall 15 facing the rotor body 22. This creates lubrication between the rotor body 22 and the mixing chamber wall 15, thereby binding escaping dust. The dust and the lubricant become a pasty mass, preventing the dust from escaping from the mixing chamber 10. The lubricant is, for example, oil, and the amount of lubricant is adjustable.

[0042] Fig. 4 shows a further embodiment of the device 100 in a schematic representation of a section of the device 100. The device 100 is the same as in Fig. 3, with the difference that the outer dust sealing ring 33 comprises a carrier part 37 and a lining part 38. The lining part 38 is arranged along the first longitudinal axis L1 between the inner dust sealing ring 31 and the carrier part 37 and bears against the inner dust sealing ring 31. The carrier part 37 bears against the hydraulic cylinder 40. The carrier part 37 is screwed to the lining part 38, for example.

[0043] When friction occurs between the two dust sealing rings 31, 33, the lining part 38 is the first to wear out. In this way, it is possible to delay the replacement of the inner dust sealing ring 31. This is advantageous because the inner dust sealing ring 31 is more difficult to disassemble due to its design. For this purpose, the lining part 38 has a softer material than the first end face 32 and / or the outer dust sealing ring 33 or is formed from such a material. Bronze or an alloy comprising bronze, for example, is used as a softer material. By dividing the outer dust sealing ring 33 into the lining part 38 and the carrier part 37, only the lining part 38 needs to be replaced when it wears out. In this way, the carrier part 37 can be designed as a one-piece ring, since replacement and the associated detachment of the carrier part 37 from the rotor shaft 25 is avoided.

[0044] The lining part 38 is made of two pieces, for example, so that it can be installed during maintenance even after initial assembly. Since the lining part 38 is intended as a wear part and is designed to wear down in a targeted manner, the first end face 32 is protected from increased wear. During operation, not the entire lining part 38 is worn down, so the groove 39 is arranged on the lining part 38. The piston ring 50 is therefore arranged in the groove 39 on the lining part 38.

[0045] Fig. 5 shows a further embodiment of the device 100 in a schematic representation of a section of the device 100. The device 100 is the same as in Fig. 4, with the difference that the groove 39 is located on the carrier part 37. Accordingly, the piston ring 50 is located in the groove 39 on the carrier part 37. This has the advantage that there is no need to worry about the complete wear of the lining part 38.

[0046] Fig. 6 shows a further embodiment of the device 100 in a schematic representation of a section of the device 100. The device 100 is the same as in Fig. 4, with the difference that the carrier part 37 and the lining part 38 each have a groove 39. A piston ring 50 is arranged in each of the two grooves 39 to improve the seal between the outer dust seal ring 33 and the first circumferential surface 17. More than one piston ring 50 can also be used per groove 39. List of reference symbols 100 Device for mixing rubber mixtures 10 Mixing chamber 15 Mixing chamber wall 16 Opening 17 first circumferential surface 20 rotors 22 rotor body 25 Rotor shaft 30 Dust seal 31 inner dust sealing ring 32 first frontal surface 33 outer dust sealing ring 34 second circumferential surface 35 second front face 361 first lubrication channel 362 second lubrication channel 37 support part 38 covering part 39 groove 40 hydraulic cylinders 50 piston ring L1 first longitudinal direction L2 second longitudinal direction

Claims

[1] Device (100) for mixing a rubber mixture, comprising - a mixing chamber (10) with a mixing chamber wall (15), - a rotor (20) comprising - a rotor body (22) rotating in the mixing chamber (10), and - a rotor shaft (25) extending along a first longitudinal direction (L1) and penetrating an opening (16) of the mixing chamber wall (15), and - a dust seal (30) suitable for sealing the mixing chamber (10), comprising - an inner dust sealing ring (31) arranged on the rotor (20), - an outer dust sealing ring (33) arranged on a first peripheral surface (17) of the opening (16), and - a piston ring (50) which is arranged on a second circumferential surface (34) of the outer dust sealing ring (33) and which is suitable for realizing a seal between the outer dust sealing ring (33) and the first circumferential surface (17). [2] Device (100) according to claim 1, comprising a hydraulic cylinder (40) which is suitable for pressing the outer dust sealing ring (33) along the first longitudinal direction (L1) against the inner dust sealing ring (31) in order to prevent the rubber mixture from escaping from the mixing chamber (10). [3] Device (100) according to one of the preceding claims, wherein a first end face (32) of the inner dust sealing ring (31) and / or a second end face (35) of the outer dust sealing ring (33) comprise hardened material or are formed from such a material. [4] Device (100) according to one of the preceding claims, wherein the outer dust sealing ring (33) comprises a first lubrication channel (361) through which a lubricant is fed to the second end face (35) for lubrication between the inner dust sealing ring (31) and the outer dust sealing ring (33). [5] Device (100) according to one of the preceding claims, wherein the mixing chamber wall (15) comprises a second lubrication channel (362) through which a lubricant is guided to the side of the mixing chamber wall (15) facing the rotor body (22). [6] Device (100) according to one of the preceding claims, wherein the piston ring (50) comprises hardened material or is formed from such a material. [7] Device (100) according to one of the preceding claims, wherein the sealing between the outer dust sealing ring (33) and the first peripheral surface (17) is effected by a plurality of piston rings (50). [8] Device (100) according to one of the preceding claims, wherein the piston ring (50) is arranged in a groove (39) of the outer dust sealing ring (33). [9] Device (100) according to one of the preceding claims, wherein the outer dust sealing ring (33) comprises a support part (37) and a lining part (38) facing the inner dust sealing ring (31). [10] Device (100) according to claim 9, wherein the groove (39) is arranged on the carrier part (37) and / or on the covering part (38).

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