A rubber mixing structure of an internal mixer rotor set

Abstract

The utility model provides a kind of rubber uniform mixing structure of internal mixer rotor set belongs to internal mixer rotor set technical field, this rubber uniform mixing structure of internal mixer rotor set includes one rotor shaft, two rotor blades, one rotor chamber, the central axis of the rotor shaft extends along horizontal direction, the rotor blade is sleeved on the outer circumferential surface of the rotor shaft, the rotor blade is connected with the rotor shaft by key;Can solve the problem that the mixing and dispersion of rubber are carried out by internal mixer rotor set in prior art, the blade shape of rotor blade and the structure of rotor chamber are relatively simple, leading to the flow pattern of rubber in internal mixer is single, easy to form local stagnation area, so that various compounding agents in rubber, especially carbon black, white carbon black etc., cannot be thoroughly and uniformly dispersed, thereby leading to mixing quality instability, affect the performance and batch consistency of final product.

Description

Technical Field

[0001] This utility model belongs to the technical field of internal mixer rotor assembly, and specifically relates to a rubber compound uniform mixing structure for internal mixer rotor assembly. Background Technology

[0002] Internal mixers are key mixing equipment in the rubber, plastics, and other polymer materials industries. Their core component is the rotor assembly, the performance of which directly determines the quality of the compounded rubber. In traditional internal mixer designs, the rotor blades typically employ simple geometric shapes, such as single or double helical structures, coupled with smooth rotor chamber walls. This structure relies primarily on the macroscopic shearing and tumbling effects generated by the high-speed rotation of the rotor for mixing. However, this traditional internal mixer structure often fails to achieve satisfactory mixing results when handling rubber compounds with high filler content, high viscosity, or extremely high dispersion requirements. Especially when adding easily agglomerated compounding agents such as carbon black, silica, and nanomaterials, the simple blade shape cannot provide sufficient strong shearing force at the microscopic level to deagglomerate and uniformly disperse these powders, leading to problems in the final compounded rubber. Undispersed agglomerates form "black spots" or "white spots." Furthermore, the simple blade structure easily creates flow dead zones between the rotor blades and the rotor chamber wall, causing some rubber compounds to remain in the internal mixer for too long, even undergoing excessive shearing and scorching, while other compounds are discharged insufficiently, severely affecting the batch stability of the mixing quality. Existing internal mixer technologies mainly compensate for structural deficiencies by increasing rotor speed, extending mixing time, or performing multiple mixing cycles. However, these methods all lead to drawbacks such as increased energy consumption, reduced production efficiency, and increased risk of rubber compound thermal degradation. Therefore, finding a uniform mixing structure for the internal mixer rotor assembly that can effectively improve the rubber compound flow pattern and enhance shear-kneading is a key technical problem urgently needing to be solved in the field of polymer material processing. Utility Model Content

[0003] In view of this, the present invention provides a rubber compound homogenization structure for a mixer rotor assembly, which can solve the problem that in the prior art, when the mixer rotor assembly mixes and disperses the rubber compound, the blade shape of the rotor blades and the structure of the rotor chamber are relatively simple, resulting in a single flow pattern of the rubber compound inside the mixer, which easily forms local stagnation areas. This makes it impossible for various compounding agents in the rubber compound, especially carbon black and silica, to be thoroughly and uniformly dispersed, thus leading to unstable mixing quality and affecting the performance and batch consistency of the final product. The homogenization effect of the existing mixer rotor assembly is difficult to meet the increasingly higher requirements of modern high-quality rubber products for mixing quality.

[0004] This utility model is implemented as follows:

[0005] This utility model provides a rubber compound homogenization structure for a rotor assembly of an internal mixer, comprising a rotor shaft, two rotor blades, and a rotor chamber. The central axis of the rotor shaft extends horizontally. The rotor blades are fitted onto the outer circumferential surface of the rotor shaft and are connected to the rotor shaft by a key. Each rotor blade has a working surface for direct contact with the rubber compound, and the working surface extends along both the axial and circumferential directions of the rotor shaft. The rotor chamber is located outside the rotor blades and has a cavity space for accommodating the rotor blades. The rotor rotates within the chamber space. The working surface of the blade has a helical geometry. The inner surface of the rotor chamber has a rotor chamber working inner surface for forming a gap with the working surface of the blade. The rotor chamber working inner surface extends along the axial direction of the rotor shaft. The rotor blade is made of alloy steel, the rotor shaft is made of structural steel, and the rotor chamber is made of wear-resistant alloy cast iron. At least two helical ridges for promoting the mixing of the adhesive are provided along the circumferential direction on the working surface of the blade. The height of the helical ridges gradually decreases along the axial direction of the rotor blade. The two ends of the rotor shaft extend out of the rotor chamber for connection with the drive mechanism.

[0006] The technical advantages of the rubber compound homogenizing structure of the internal mixer rotor assembly provided by this utility model are as follows: The rubber compound homogenizing structure of the internal mixer rotor assembly achieves reliable power transmission between the rotor blades and the rotor shaft by fitting two rotor blades onto the outer circumferential surface of the rotor shaft and connecting them with a key. This ensures that the rotor blades can rotate stably within the rotor chamber and apply shearing and mixing action to the rubber compound. The working surface of the rotor blades is designed in a helical shape. This helical shape can generate continuous axial pushing and radial tumbling action on the rubber compound when the rotor blades rotate, effectively preventing the rubber compound from stagnating within the internal mixer. The stagnation in the section ensures that the rubber compound receives sufficient movement and mixing; the arrangement of at least two helical ridges along the circumferential direction on the working surface of the blades enhances the local shearing and dispersion effect of the rubber compound during the mixing process, promoting the uniform dispersion of compounding agents; the height of the helical ridges gradually decreases along the axial direction of the rotor blades. This height variation design allows the rubber compound to experience progressively increasing compression and shear strength as it moves from the feeding zone to the discharging zone, which is beneficial for adaptive mixing of the rubber compound at different stages, ultimately achieving uniform mixing of the rubber compound, avoiding uneven mixing, and improving the mixing quality.

[0007] Based on the above technical solution, the rubber compound homogenization structure of the internal mixer rotor assembly of this utility model can be further improved as follows:

[0008] The spiral ridges on the rotor blades are arranged in an alternating pattern, such that the axial distance between adjacent spiral ridges changes along the circumferential direction.

[0009] The beneficial effects of the above-mentioned improvement scheme are as follows: The spiral ridges are distributed in an alternating pattern on the rotor blades, causing the axial distance between adjacent spiral ridges to change along the circumferential direction. This alternating arrangement breaks the uniformity of the rubber flow, forcing the rubber to undergo more complex reorientation and diversion and merging in the axial and circumferential directions when the rotor blades rotate, increasing the relative movement and alternating mixing frequency between different positions within the rubber. The change in axial distance along the circumferential direction further intensifies the shear rate difference and pressure fluctuation in local areas, significantly improving the dispersion effect of the rubber at the microscopic level, effectively avoiding the mixing dead angle caused by a single shear direction, thereby greatly improving the uniform mixing efficiency of the internal mixer rotor group for the rubber without adding complex parts.

[0010] Furthermore, the rotor blades are provided with grooves for improving the shear force of the rubber compound, and the grooves extend axially along the working surface of the blades.

[0011] The beneficial effects of the above-mentioned improvement scheme are as follows: The rotor blades are provided with grooves for improving the shear force of the rubber compound. The grooves extend axially along the working surface of the blades. This structure utilizes the grooves to form local accumulation and strong extrusion of the rubber compound when the blades rotate, increasing the contact friction between the rubber compound and the rotor blade surface and the shear stress between internal molecules, which significantly improves the shearing and kneading ability of the rubber compound. The axially extending grooves can guide the rubber compound to generate additional eddies and tumbling during the mixing process, breaking the original flow pattern. This is beneficial for re-entraining the rubber compound adhering to the blade surface or rotor chamber wall into the main flow, ensuring that all rubber compounds can be fully mixed and dispersed, effectively preventing the adhesion and retention of rubber compounds on the inner wall of the internal mixer, and further improving the mixing uniformity.

[0012] Furthermore, the cross-sectional shape of the groove is arc-shaped, and the arc-shaped groove has a curvature that varies along the depth direction.

[0013] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the cross-sectional shape of the groove is arc-shaped, and the arc-shaped groove has a varying curvature along the depth direction. This arc-shaped cross-sectional design avoids excessive stress concentration on the rubber material by sharp edges, allowing the rubber material to flow smoothly in the groove and reducing the risk of local overheating. The varying curvature along the depth direction causes the groove to exert different compression and shearing effects on rubber material layers of different thicknesses. The deeper rubber material is subjected to milder shearing, while the surface rubber material is subjected to stronger shearing, forming a gradient shear field, which promotes the dispersion and homogenization of different components inside the rubber material. This special curvature variation effectively improves the filling and emptying efficiency of the rubber material in the groove, further enhancing the groove's ability to mix and disperse the rubber material.

[0014] Furthermore, the working surface of the rotor blade is provided with a stepped structure for forming a shearing action, and the stepped structure is arranged to gradually increase in the radial direction of the rotor blade.

[0015] The beneficial effects of the above-mentioned improvement scheme are as follows: The working surface of the rotor blades is provided with a stepped structure for forming a shearing action. The stepped structure is arranged to gradually increase in the radial direction of the rotor blades. When the rotor blades rotate, this stepped structure forms multi-level shear surfaces at the edges and sides of the steps, which forces the rubber compound to undergo multiple rapid changes in speed and direction when flowing through these steps, generating a strong multi-level shearing action. The gradually increasing radial direction ensures that the shearing action has an increasing or decreasing intensity change from the blade root to the blade tip, realizing a gradual mixing process of the rubber compound. In particular, a high shear zone is formed at the acute angle of the steps, which effectively tears and disperses agglomerates, improves the dispersion uniformity of compounding agents, and significantly enhances the mixing efficiency and quality of the internal mixer rotor assembly.

[0016] Furthermore, the ratio of the width of the stepped structure along the axial direction of the rotor blade to the minimum circumferential distance between two adjacent helical ridges is greater than 1:3.

[0017] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the ratio of the width of the stepped structure along the axial direction of the rotor blade to the minimum circumferential distance between two adjacent helical ridges is greater than 1:3. This dimensional ratio ensures that the stepped structure has sufficient width in the axial direction to effectively divert and shear the flowing rubber material, while its width relative to the distance between the helical ridges does not excessively occupy the flow channel of the rubber material. The ratio of more than 1:3 allows the stepped structure and the helical ridges to form a composite motion mode that combines axial pushing and turning with strong radial shearing when they work together. This avoids insufficient shearing effect due to the stepped structure being too narrow or flow obstruction due to the stepped structure being too wide, thereby optimizing the stress state of the rubber material on the rotor blade and maximizing the uniform mixing efficiency of the rotor assembly.

[0018] Furthermore, the outer circumferential surface of the rotor blade is provided with a guide groove for guiding the flow of the rubber material, and the guide groove extends along the axial and circumferential directions of the rotor blade.

[0019] The beneficial effects of the above-mentioned improvement scheme are as follows: the outer circumferential surface of the rotor blade is provided with a guide groove for guiding the flow of rubber material. The guide groove extends along the axial and circumferential directions of the rotor blade. When the blade rotates, the guide groove can capture part of the rubber material pushed by the blade and guide it back to other areas of the rotor chamber along the specific direction of the channel. This enhances the macroscopic circulation and tumbling of the rubber material inside the internal mixer and effectively avoids local short circuits or stagnation of the rubber material. The axial and circumferential extension design allows the guide groove to adapt to the complex flow trajectory of the rubber material, forming a continuous internal circulation loop, which further promotes the full convection mixing inside the rubber material and significantly improves the overall mixing uniformity of the internal mixer for large-volume rubber materials.

[0020] Furthermore, the inner working surface of the rotor chamber is provided with a protruding structure that matches the working surface of the rotor blades, and the protruding structure is used to enhance the kneading effect on the rubber material.

[0021] The beneficial effects of the above-mentioned improvement scheme are as follows: The inner working surface of the rotor chamber is provided with a protruding structure that matches the working surface of the rotor blades. The protruding structure is used to enhance the kneading effect on the rubber material. When the rotor blades rotate, the protruding structure forms a dynamic and changing narrow gap with the working surface of the blades. When the rubber material flows through these gaps, it will be subjected to strong compression and kneading action. This action is similar to the effect of a kneader, which efficiently deconstructs and disperses the internal molecular structure of the rubber material and the agglomerates of fillers, thereby greatly improving the efficiency of dispersion and mixing. The presence of the protruding structure increases the residence time of the rubber material in the rotor chamber, allowing the rubber material to undergo mixing and shearing treatment for a longer period of time, further improving the mixing quality.

[0022] Furthermore, the number of protrusions on the inner working surface of the rotor chamber is eight, and they are evenly distributed along the circumference of the rotor chamber.

[0023] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the number of the raised structures on the working inner surface of the rotor chamber is 8, and they are evenly distributed along the circumference of the rotor chamber. The 8 evenly distributed raised structures ensure that the rubber material is subjected to a strong kneading and squeezing action at 8 different positions during each rotation of the rotor blade. This high-frequency, multi-point kneading treatment greatly improves the uniformity and efficiency of mixing and avoids mixing dead zones caused by insufficient number or uneven distribution of raised structures. The uniform distribution ensures that the rubber material is treated evenly along the entire length of the rotor blade, further improving the overall mixing quality.

[0024] Furthermore, the axial length of the protrusion structure on the inner working surface of the rotor chamber is greater than the axial length of the groove on the rotor blade.

[0025] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the axial length of the protrusion structure on the inner working surface of the rotor chamber is greater than the axial length of the groove on the rotor blade. This axial length design relationship ensures that the protrusion structure on the rotor chamber has a sufficiently long coverage range in the axial direction, so that its kneading effect on the flowing rubber can continue for a longer distance, enhancing the thoroughness of kneading; the axial length of the protrusion structure is greater than the axial length of the groove, so that during the rotation of the rotor blade, the protrusion structure not only interacts with the groove, but also cooperates with other parts of the working surface of the blade to form more complex and varied gaps and flow paths, thereby maximizing the role of the rotor chamber wall in promoting rubber mixing.

[0026] Compared with existing technologies, the beneficial effects of the rubber compound homogenization structure of the internal mixer rotor assembly provided by this utility model are as follows: The rubber compound homogenization structure of the internal mixer rotor assembly of this utility model, by introducing rotor blades with helical ridges, grooves, and stepped structures, and the inner working surface of the rotor chamber with protruding structures, collectively forms a complex, multi-stage shearing and kneading mixing field. This composite structure significantly improves the technical problems of single rubber compound flow patterns and insufficient mixing in existing technologies. The helical blade working surface and the staggered helical ridges cause the rubber compound to be pushed and tumbled simultaneously in the axial and circumferential directions, effectively avoiding rubber compound stagnation and short circuits. The grooves and stepped structures... The structure provides localized strong shear zones, especially the stepped structure that gradually rises radially, creating multi-stage shearing that efficiently tears and disperses compounding agent agglomerates. The raised structures on the inner working surface of the rotor chamber, in conjunction with the rotor blades, apply a strong kneading action to the rubber compound, further improving dispersion uniformity. Through the ingenious design of the shape, size, and positional relationship of these components, the homogenizing structure of this invention not only enhances the shearing, extrusion, and kneading action on the rubber compound but also promotes macroscopic convection and microscopic dispersion, ultimately achieving efficient, thorough, and uniform mixing of the rubber compound. This significantly improves the quality and production efficiency of the compound, overcoming the problem of uneven mixing in existing technologies. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic diagram of a rubber compound homogenization structure for a rotor assembly of an internal mixer;

[0029] Figure 2 This is a schematic diagram of the contact position between the rotor blades and the rotor chamber.

[0030] Figure 3 This is a schematic diagram of the cross-sectional structure of the rotor blades;

[0031] The attached diagram lists the components represented by each number as follows:

[0032] 1. Rotor shaft; 2. Rotor blades; 21. Groove; 22. Helical ridge; 3. Rotor chamber; 31. Protruding structure. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0034] like Figure 1-3 The diagram shows a schematic of the rubber compound homogenization structure of a mixer rotor assembly provided by this utility model. The structure includes a rotor shaft 1, two rotor blades 2, and a rotor chamber 3. The central axis of the rotor shaft extends horizontally. The rotor blades are fitted onto the outer circumferential surface of the rotor shaft and are connected to the rotor shaft by a key. Each rotor blade has a working surface for direct contact with the rubber compound, extending along both the axial and circumferential directions of the rotor shaft. The rotor chamber is located outside the rotor blades and has a cavity space for accommodating the rotor blades. The blades rotate within the chamber space of the rotor chamber. The working surface of the blades has a helical geometry. The inner surface of the rotor chamber has a working inner surface for forming a gap with the working surface of the blades. The working inner surface of the rotor chamber extends along the axial direction of the rotor shaft. The rotor blades are made of alloy steel, the rotor shaft is made of structural steel, and the rotor chamber is made of wear-resistant alloy cast iron. At least two helical ridges 22 for promoting the mixing of the adhesive are provided along the circumferential direction on the working surface of the blades. The height of the helical ridges gradually decreases along the axial direction of the rotor blades. The two ends of the rotor shaft extend out of the rotor chamber for connection with the drive mechanism.

[0035] In the above technical solution, the spiral ridges are distributed in an alternating manner on the rotor blades, so that the axial distance between adjacent spiral ridges changes along the circumferential direction.

[0036] Furthermore, in the above technical solution, the rotor blade is provided with a groove 21 for improving the shear force of the rubber material, and the groove extends axially along the working surface of the blade.

[0037] Furthermore, in the above technical solution, the cross-sectional shape of the groove is arc-shaped, and the arc-shaped groove has a curvature that varies along the depth direction.

[0038] Furthermore, in the above technical solution, the working surface of the rotor blade is provided with a stepped structure for forming a shearing action, and the stepped structure is arranged to gradually increase in the radial direction of the rotor blade.

[0039] Furthermore, in the above technical solution, the ratio of the width of the stepped structure along the rotor blade axial direction to the minimum circumferential distance between two adjacent helical ridges is greater than 1:3.

[0040] Furthermore, in the above technical solution, a guide groove for guiding the flow of rubber material is provided on the outer circumferential surface of the rotor blade, and the guide groove extends along the axial direction and circumferential direction of the rotor blade.

[0041] Furthermore, in the above technical solution, a protruding structure 31 is provided on the inner working surface of the rotor chamber, which cooperates with the working surface of the rotor blades. The protruding structure is used to enhance the kneading effect on the rubber material.

[0042] Furthermore, in the above technical solution, there are 8 protrusions on the inner working surface of the rotor chamber, which are evenly distributed along the circumference of the rotor chamber.

[0043] Furthermore, in the above technical solution, the axial length of the protrusion structure on the inner working surface of the rotor chamber is greater than the axial length of the groove on the rotor blade.

[0044] The following is a specific embodiment 1 of this utility model: The rubber compound homogenizing structure of the internal mixer rotor assembly in this embodiment 1 includes a rotor shaft, two rotor blades, and a rotor chamber. The rotor shaft is made of 45 steel and is tightly connected to the two rotor blades by a spline connection. The rotor blades are made of high-chromium cast iron, and the working surface of the blades is designed with a double helix structure. The helix angle of the blades is 20°. Two helical ridges are evenly arranged along the circumference on the working surface of each rotor blade. The two helical ridges are staggered along the axial direction. The height of the helical ridges increases from 2mm at the feed end. The axial length decreases uniformly to 0.5mm at the discharge end, with a height reduction gradient of 25mm / m. Five axially extending grooves are provided on the rotor blades. The cross-section of these grooves is arc-shaped, and the curvature in the depth direction gradually increases from the outer surface inwards to enhance the kneading effect on high-viscosity adhesives. Furthermore, a three-tiered stepped structure is provided on the working surface of the blades near the blade tip. This stepped structure gradually increases in elevation along the radial direction of the rotor blades. The axial width of the stepped structure is 1 / 8 of the total axial length of the rotor blades, and the minimum circumferential distance between it and two adjacent helical ridges is... The ratio is 1:25; the rotor chamber is made of nickel-hard cast iron, and its working inner surface has eight hemispherical protrusions evenly distributed along the circumference. The axial length of the protrusions is 12 times the axial length of the grooves on the rotor blades, and the height of the protrusions is 5mm. The protrusions are used to apply a strong kneading effect to the rubber compound flowing through them when the rotor blades rotate; four guide grooves extending along the axial and circumferential directions are provided on the outer circumferential surface of the rotor blades to enhance the macroscopic circulation of the rubber compound; in practical applications, this rotor assembly is used to mix natural rubber compound containing 70 parts carbon black. With the rotational speed set at 40 r / min and the mixing temperature controlled at 140℃, the carbon black agglomerates in the rubber compound are rapidly and efficiently dispersed through the combined shearing action of the spiral ridges, grooves, and stepped structures on the rotor blades, as well as the kneading action provided by the protruding structure of the rotor chamber. At the same time, the function of the guide channel ensures that the rubber compound is fully turned over and convectively mixed. The structure of this embodiment significantly improves the dispersion uniformity of carbon black through the synergy of multiple mixing mechanisms, solves the problem of "black spots" that easily occur when traditional internal mixers process high-filler rubber compounds, shortens the mixing cycle, and improves production efficiency.

[0045] The following is another specific embodiment 2 of this utility model: This embodiment 2 is based on embodiment 1, and the cross-sectional shape of the groove on the rotor blade used to improve the shear force of the rubber is improved to an inverted triangle. The depth of the groove along the axial direction gradually decreases radially from the root of the blade to the tip of the blade. This inverted triangular groove forms a stronger concentrated shear stress on the rubber when the blade rotates. The two hypotenuses of the inverted triangle contact the rubber to form two shear surfaces, which increases the effective shear area. The design of the groove depth gradually decreasing radially makes the shear strength have a gradient change in the radial direction, realizing the progressive shearing treatment of the rubber, further optimizing the shearing and kneading effect, and improving the ability to break up and disperse hard compounding agents.

[0046] The following is another specific embodiment 3 of this utility model: This embodiment 3 is based on embodiment 1, but the number of protrusions on the inner working surface of the rotor chamber is increased to 10 and they are evenly distributed along the circumference of the rotor chamber. At the same time, the geometry of the protrusions is changed from hemispherical to cylindrical. The narrow gap formed between the cylindrical protrusions and the working surface of the rotor blades has a longer axial contact distance, which enhances the continuity of the kneading action. The increase in the number of protrusions to 10 allows the rubber material to be kneaded at a higher frequency every time the rotor blades rotate, which effectively improves the mixing uniformity of synthetic rubber materials with high viscoelasticity.

[0047] The following is another specific application scenario of this utility model, embodiment 4. This embodiment is applied to the internal mixing of high-fill-content tire tread rubber, including a rotor shaft, two rotor blades, and a rotor chamber, described in detail below: The rotor blades of this embodiment are made of nickel-based high-temperature alloy to cope with the huge frictional heat and wear generated during the mixing process of high-fill-content rubber. The working surface of the rotor blade has four helical ridges, which are symmetrically staggered in the axial direction. Their height decreases uniformly from 35mm at the feed end to 1mm at the discharge end. The ridges adopt a variable pitch design, with a larger pitch in the feed area, which is conducive to rapid feeding, and a smaller pitch in the mixing area, which enhances pushing and shearing. The blade is provided with inverted trapezoidal grooves distributed in a grid pattern along the axial and circumferential directions. The groove depth is 4mm. The grid pattern increases the complexity of the rubber flow path and significantly enhances the squeezing and kneading effect on the rubber. The working surface of the blade is provided with a five-level stepped structure with a step height difference of 0.8mm. The stepped structure is along the axial direction. With a width-to-minimum circumferential distance ratio of 1:18, this multi-stage stepped structure provides extremely high shear stress when compounding highly filled tread compounds, efficiently dispersing large amounts of carbon black and silica additives. The rotor chamber is cast from a highly wear-resistant and thermally conductive copper-based alloy to ensure that the heat generated during the compounding process can be quickly dissipated. Its working inner surface has 12 ellipsoidal protrusions evenly distributed along the circumference, with the axial length of the protrusions set to 15 times the axial width of the stepped structure on the rotor blades, providing a continuous and strong kneading action. In application, this rotor assembly is used to compound high-performance tread compounds containing 80 parts carbon black and 20 parts silica. The rotor speed is set at 50 r / min, and the compounding temperature is controlled at 150℃. The complex blade geometry and the protrusions in the rotor chamber work together to ensure that the highly filled additives are evenly dispersed in a short time, avoiding the degradation of compound performance caused by insufficient dispersion. The final compounded tread compound has excellent wear resistance and low rolling resistance.

[0048] Specifically, the principle of this utility model is as follows: The rubber compound homogenizing structure of the internal mixer rotor assembly of this utility model consists of a rotor shaft, two rotor blades, and a rotor chamber. The rotor shaft is made of structural steel such as 40Cr or 45 steel, which has high precision requirements. It is used to transmit torque and support the rotor blades. Its two ends extend outside the rotor chamber for connecting to drive mechanisms such as gear reducers or motors. The two rotor blades are made of high wear-resistant alloy steel, such as CrNiMo alloy steel or high-chromium cast iron, to cope with wear under high shear forces. The rotor blades are tightly fitted onto the outer circumferential surface of the rotor shaft by key or spline connection to ensure synchronous rotation. The rotor blades have a helical blade working surface, and two or three helical ridges are arranged along the circumferential direction on the blade working surface, preferably two. The helical ridges are staggered on the rotor blades, and the height of the helical ridges extends from the feed end to the discharge end along the axial direction of the rotor blades. The reduction gradient is preferably controlled between 1 and 3 mm / m. The rotor blade is also provided with a groove extending axially along the working surface of the blade. The cross-sectional shape of the groove is arc-shaped, and the curvature gradually increases from the outer surface to the inner surface along the depth direction to optimize the shearing effect. In addition, a stepped structure is provided on the working surface of the blade. The stepped structure is arranged to gradually increase from the inside to the outside along the radial direction of the rotor blade. The width of the stepped structure along the axial direction is preferably between 1 / 10 and 1 / 8 of the total axial length of the blade. The rotor chamber is made of wear-resistant alloy cast iron, such as nickel hard cast iron or high chromium cast iron, which has high strength and wear resistance. Its chamber space is used to accommodate the rotation of the rotor blade. Eight protrusions are evenly distributed along the circumferential direction on the inner working surface of the rotor chamber. The axial length of the protrusions is preferably greater than the axial length of the grooves on the rotor blade. The protrusions are used to knead and squeeze the rubber material when the rotor blade rotates at high speed.

[0049] The reason this invention can solve the technical problem of uneven rubber mixing in existing technologies lies in its composite structural design of rotor blades and rotor chamber, which establishes a highly efficient, multi-dimensional, and gradient shear-kneading mixing field inside the internal mixer. Specifically, the spiral blade working surface provides axial pushing and radial tumbling capabilities for the main body of the rubber compound, ensuring macroscopic convection. The staggered and height-gradient spiral ridges, on the basis of macroscopic flow, increase local circumferential shear and pressure fluctuations, effectively diverting and re-merging the rubber compound, promoting large-scale homogenization. The groove and stepped structure are key to achieving microscopic dispersion. When the rubber compound flows through the groove, it is subjected to strong compression and shear. When it flows through the radially gradually rising stepped structure, the rubber compound is forced through a multi-stage variable speed region, generating extremely high local shear stress at the edge of the steps. Shear stress effectively tears apart compounding agent agglomerates in the rubber compound, achieving fine dispersion of the compounding agents in the polymer matrix. Simultaneously, eight uniformly distributed protrusions on the inner working surface of the rotor chamber create dynamic, constantly changing narrow gaps with the working surface of the rotor blades during high-speed rotation. This forces the rubber compound to undergo high-intensity "kneading" and "compression" as it flows through. This kneading effect is particularly significant in improving the dispersion of high-viscosity rubber compounds, overcoming the shortcomings of relying solely on shearing to thoroughly disperse agglomerates. The design of the axial length of the protrusions being greater than that of the grooves ensures full coverage of the kneading effect. Ultimately, the synergistic effect of these three mixing mechanisms—macro-convective, micro-shear, and strong kneading—breaks the single flow pattern of traditional internal mixers, allowing the rubber compound to be thoroughly and evenly processed in three-dimensional space, thereby significantly improving the dispersion uniformity and mixing quality of the compound.

[0050] The operation or use of the rubber compound mixing structure of this internal mixer rotor assembly first involves adding the raw rubber to be mixed and various compounding agents, such as carbon black, zinc oxide, and stearic acid, into the rotor chamber space through the top feed inlet of the internal mixer according to the order and proportion specified in the formula. Before starting the internal mixer, it is necessary to ensure that the rotor shaft is reliably connected to the external drive mechanism, such as the motor and reducer, through the coupling, and to check that the temperature control system of the rotor chamber is in normal working condition. After starting the drive mechanism, the rotor shaft drives the two rotor blades mounted on it. Inside the rotor chamber, the rotors rotate at high or medium speeds in opposite directions, typically between 20 and 60 r / min. The helical blades of the rotor initially exert axial pushing and radial tumbling forces on the rubber compound within the chamber, causing the compound to move axially from the feed end to the discharge end along the rotor shaft and continuously tumble in the circumferential direction. During this pushing process, the rubber compound flows through the staggered helical ridges on the rotor blades, is diverted, and undergoes initial shearing and pressure fluctuations, promoting initial homogenization of the compound. Subsequently, the compound flows through the rotor... The axial grooves and radially rising stepped structures on the blades subject the rubber compound to strong local shear stress and extrusion in these areas. In particular, the multiple shear surfaces formed radially by the stepped structures efficiently tear and disperse the agglomerates of compounding agents, achieving fine dispersion. Simultaneously, during each rotation cycle of the rotor blades, the rubber compound flows multiple times through the dynamic narrow gap formed between the eight evenly distributed protrusions on the inner working surface of the rotor chamber and the working surface of the blades, experiencing strong kneading action, further improving the uniformity of dispersion. Through the guide grooves on the rotor blades, some of the rubber compound is redirected to other areas of the rotor chamber, enhancing the macroscopic convection circulation of the rubber compound and avoiding local stagnation. The entire mixing process requires controlling the temperature of the rotor chamber wall and rotor blades at the target mixing temperature, such as 120–160°C, through an external cooling or heating system, depending on the type and formulation of the rubber compound, to ensure that the mixing takes place within the optimal temperature window. After the predetermined mixing time or after reaching the set energy consumption value, the bottom discharge gate of the internal mixer is opened to discharge the uniformly mixed rubber compound, thus completing the entire mixing process.

Claims

1. A rubber compound homogenization structure for a rotor assembly of an internal mixer, characterized in that, The device includes a rotor shaft, two rotor blades, and a rotor chamber. The central axis of the rotor shaft extends horizontally. The rotor blades are fitted onto the outer circumferential surface of the rotor shaft and are connected to the rotor shaft by a key. Each rotor blade has a working surface for direct contact with the adhesive material, extending along both the axial and circumferential directions of the rotor shaft. The rotor chamber is located outside the rotor blades and has a cavity space for accommodating the rotor blades. The rotor blades rotate within the cavity space of the rotor chamber. The working surface of the blades has a helical geometry. The inner surface of the rotor chamber has a working inner surface for forming a gap with the working surface of the blades, extending along the axial direction of the rotor shaft. The rotor blades are made of alloy steel, the rotor shaft is made of structural steel, and the rotor chamber is made of wear-resistant alloy cast iron. At least two helical ridges are provided circumferentially on the working surface of the blades to promote adhesive mixing, with the height of the helical ridges gradually decreasing along the axial direction of the rotor blades. The rotor shaft extends out of the rotor chamber at both ends for connection to a drive mechanism.

2. The rubber compound homogenization structure of a mixer rotor assembly according to claim 1, characterized in that, The helical ridges on the rotor blades are arranged in an alternating pattern, so that the axial distance between adjacent helical ridges changes along the circumferential direction.

3. The rubber compound homogenization structure of a mixer rotor assembly according to claim 2, characterized in that, The rotor blades are provided with grooves for improving the shear force of the rubber compound, and the grooves extend axially along the working surface of the blades.

4. The rubber compound homogenization structure of a mixer rotor assembly according to claim 3, characterized in that, The groove has a circular arc cross-sectional shape, and the circular arc groove has a curvature that varies along the depth direction.

5. The rubber compound homogenization structure of a mixer rotor assembly according to claim 4, characterized in that, The rotor blades have a stepped structure on their working surface for generating shearing action, and the stepped structure is arranged to gradually increase in the radial direction of the rotor blades.

6. The rubber compound homogenization structure of a mixer rotor assembly according to claim 5, characterized in that, The ratio of the width of the stepped structure along the axial direction of the rotor blade to the minimum circumferential distance between two adjacent helical ridges is greater than 1:

3.

7. The rubber compound homogenization structure of a mixer rotor assembly according to claim 6, characterized in that, The outer circumferential surface of the rotor blade is provided with a guide groove for guiding the flow of rubber material, and the guide groove extends along the axial and circumferential directions of the rotor blade.

8. The rubber compound homogenization structure of a mixer rotor assembly according to claim 7, characterized in that, The inner working surface of the rotor chamber is provided with a protruding structure that matches the working surface of the rotor blades. The protruding structure is used to enhance the kneading effect on the rubber material.

9. The rubber compound homogenization structure of a mixer rotor assembly according to claim 8, characterized in that, The number of protrusions on the inner working surface of the rotor chamber is eight, and they are evenly distributed along the circumference of the rotor chamber.

10. The rubber compound homogenization structure of a mixer rotor assembly according to claim 9, characterized in that, The axial length of the protrusion on the inner working surface of the rotor chamber is greater than the axial length of the groove on the rotor blade.

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