A hub-driven grinding device and a method of retrofitting the same

Abstract

The present application belongs to vertical roller mill equipment technical field, especially to a kind of hub-driven grinding device and its reforming method, the hub-driven grinding device includes mill roller, the mill roller rear end is equipped with straight intersection shaft speed reducer, straight intersection shaft speed reducer passes through the torsion shaft in mill roller, drive fixed shaft wheel system located in the front end of mill roller;The fixed shaft wheel system includes sun gear located at the end of torsion shaft, the sun gear is engaged with planetary gear, the planetary gear is installed between axle end cover and planet carrier by planetary gear pin shaft, the hub of the mill roller is equipped with inner ring gear, the inner ring gear is engaged with planetary gear.The present application provides a kind of hub-driven grinding device and its reforming method, improves the grinding efficiency, the output of mill, and saves power consumption.

Description

Technical Field

[0001] This invention belongs to the technical field of vertical roller mill equipment, and particularly relates to a hub-driven grinding device and its modification method. Background Technology

[0002] Existing technology:

[0003] Vertical roller mills are widely used in the production of powder materials such as raw materials, pulverized coal, and cement. However, due to technological advancements in roller presses, particularly in raw material grinding, the advantages of vertical roller mills, particularly their low power consumption, have gradually diminished. Currently, energy conservation and emission reduction are top priorities for production enterprises. Existing raw material mill retrofitting solutions generally include air rings, high-efficiency classifiers, and adjustments to operating parameters, but there have been no significant improvements in the grinding mechanism itself. Some owners are even willing to invest heavily in replacing their original vertical mill systems with raw material roller press final grinding systems.

[0004] However, the inventors of this application have discovered that the aforementioned prior art has at least the following technical problems:

[0005] The working principle of a roller press consists of two opposing and synchronously rotating extrusion rollers. The material is actively bitten into the grinding zone and rapidly crushed in the high-pressure zone, but it can only perform one grinding cycle. The working principle of a vertical mill is that the grinding disc rotates actively, while the grinding rollers rotate passively, extruding the material on the grinding disc. This allows for multiple grinding cycles within the mill, but material can accumulate and slip at the front of the grinding rollers, leading to significant mill vibration. When grinding easily grindable materials, increasing the roller pressure in a vertical mill exacerbates the vibration problem. Comparing the two, the roller press has two actively rotating extrusion rollers, while the vertical mill only has an actively rotating grinding disc. The roller press has slightly lower unit projected pressure and grinding efficiency compared to the roller press, but its investment cost is higher.

[0006] The difficulty and significance of solving the above technical problems:

[0007] Therefore, based on these issues, a hub-driven grinding device and its modification method are proposed. Compared with conventional vertical mills and roller presses, it offers several advantages: the material is actively bitten into the grinding zone on the grinding disc, allowing for higher roller pressure and multiple grinding processes within the mill; it solves the problem of material accumulation at the front end of the grinding rollers affecting the stability of the material layer in vertical mills, thus improving grinding efficiency; and its investment cost in upgrading and modifying vertical mills is lower than that of roller presses, making it of significant practical importance. Summary of the Invention

[0008] The purpose of this application is to provide a hub-driven grinding device and its modification method to solve the technical problems in the prior art, thereby improving grinding efficiency, mill output, and saving power consumption.

[0009] The technical solution adopted in this application embodiment to solve the technical problems existing in the prior art is as follows:

[0010] A hub-driven grinding device includes a grinding roller, a right-angle shaft reducer at the rear end of the grinding roller, and a fixed-axis gear train at the front end of the grinding roller via a torsion shaft inside the grinding roller. The fixed-axis gear train includes a sun gear at the end of the torsion shaft, which meshes with planet gears. The planet gears are mounted between a shaft end cover and a planet carrier via planet gear pins. An internal gear ring is installed inside the hub of the grinding roller, and the internal gear ring meshes with the planet gears.

[0011] The planetary carrier is fixed relative to the grinding roller shaft, and the hub rotates in the opposite direction to the sun gear.

[0012] The embodiments of this application may also employ the following technical solutions:

[0013] In the aforementioned hub-driven grinding device, the end cap of the grinding roller shaft is further connected to the planetary carrier via a planetary gear pin. A spacer and a sliding bearing are provided between the planetary gear pin and the planetary gear, with the two spacers located at both ends of the sliding bearing.

[0014] A fixed-axis gear train is a planetary gear transmission with a fixed planetary carrier. The sun gear meshes with three planetary gears simultaneously. This configuration allows for a smaller outer diameter of the torque shaft, which in turn allows for smaller dimensions of the grinding roller shaft, upper rocker arm, and fixed-axis gear train, enabling the construction of the hub-driven grinding device at a lower cost.

[0015] In the aforementioned hub-driven grinding device, the grinding roller shaft is further described as having a hollow structure, with a self-aligning bearing installed inside the shaft end cover, and the torque shaft is fixed inside the grinding roller shaft via a thrust self-aligning roller bearing and a self-aligning bearing.

[0016] This structure facilitates the use of a variable frequency motor located outside the mill to drive the hub, enabling the active rotation of the grinding rollers. This configuration allows the torque shaft to be rotatably fixed within the grinding roller shaft, transmitting rotation and torque.

[0017] In the aforementioned hub-driven grinding device, the grinding roller shaft is further provided with an oil inlet hole and an oil return hole. The grinding roller bearing and the fixed shaft gear train have a common oil chamber, that is, part of the grinding roller bearing and the fixed shaft gear train are located below the grinding roller oil level line. The oil chamber is lubricated by forced circulation of thin oil and is equipped with a separate lubrication oil station.

[0018] Approximately one-third of the way down the grinding roller bearing is below the oil level. Oil enters the chamber through the inlet hole on the grinding roller shaft, using a high-level inlet and low-level return system. The circulating oil removes heat generated during operation and impurities from the oil chamber, extending the service life of the bearings and the fixed-shaft gear train.

[0019] In the aforementioned hub-driven grinding device, the grinding disc is further driven by the main motor via a reducer;

[0020] The rocker arm device includes an upper rocker arm, a lower rocker arm, and a rocker arm shaft, which are fixed in a bearing seat in the bracket. The lower rocker arm is hinged to a hydraulic cylinder.

[0021] The grinding roller assembly rotates around the rocker arm shaft under the pulling force of the hydraulic cylinder, grinding the material on the grinding disc. The pulling force of the hydraulic cylinder is transmitted to the material on the grinding disc and the grinding disc through the bracket, lower rocker arm, upper rocker arm, grinding roller shaft, hub, and roller sleeve; the grinding roller rotates around the rocker arm shaft under the action of the hydraulic cylinder, compacting and grinding the material on the grinding disc; the upper rocker arm can rotate around the rocker arm shaft and can be flipped out from the lower rocker arm for easy installation and maintenance of the grinding roller.

[0022] In the aforementioned hub-driven grinding device, the grinding roller assembly is further fixedly connected within the upper rocker arm. The grinding roller assembly includes a roller sleeve, a hub, a grinding roller bearing, and a grinding roller shaft. The roller sleeve and the hub are detachably rigidly connected. A grinding roller bearing is provided between the hub and the grinding roller shaft. The grinding roller bearing is a double-row tapered bearing and a cylindrical bearing, wherein the double-row tapered bearing is located at the large end of the grinding roller, and the cylindrical bearing is located at the small end of the grinding roller.

[0023] This configuration results in the smallest bearing size and the best cost; the double-row tapered bearings are installed with negative axial clearance, which helps to increase the service life of the grinding roller bearings and the fixed-axis gear train.

[0024] In the aforementioned hub-driven grinding device, the right-angle shaft reducer is further driven by a variable frequency motor via a universal coupling. The right-angle shaft reducer is connected to a torque shaft via a drum gear coupling. The variable frequency motor is horizontally mounted and fixed on a motor support, which is made of concrete. The centerline of the variable frequency motor is arranged at 90° to the centerline of the grinding roller.

[0025] A variable frequency motor, fixed on a motor support, is connected to a right-angle shaft reducer via a universal coupling, thereby driving the grinding roller assembly. The grinding roller assembly is directly driven by the variable frequency motor and is evenly distributed on the grinding disc. By adjusting the motor speed, the grinding rollers and the grinding disc are ensured to rotate synchronously in opposite directions, thus achieving the optimal operating state of the vertical mill.

[0026] The centerline C1 of the variable frequency motor is arranged at 90° with the centerline C2 of the grinding roller, which facilitates the installation and maintenance of the grinding roller and the horizontal installation of the motor. The universal coupling can compensate for the fluctuation of the right-angle shaft reducer during the operation of the grinding roller. The drum gear coupling can compensate for the misalignment during installation and the deformation of the torsion shaft after bearing load, effectively reducing the impact of impact load on the right-angle shaft reducer and protecting the gears.

[0027] In the aforementioned hub-driven grinding device, the right-angle shaft reducer further includes: a bevel gear shaft, a bevel gear, a gear shaft, a large gear, and an output shaft. The bevel gear shaft is provided with a bevel gear and meshes with the bevel gear mounted on the gear shaft. The small gear is integrally formed on the gear shaft and meshes with the large gear mounted on the output shaft. The output shaft is a solid shaft and is connected to a drum-shaped gear coupling.

[0028] In the aforementioned hub-driven grinding device, the bevel gear and the output end of the output shaft are located on the same side of the reducer housing.

[0029] The gears and the output shaft are located on the same side of the reducer housing, facilitating gear lubrication. The right-angle shaft reducer includes a single-stage bevel gear drive and a two-stage parallel shaft drive, both using oil bath lubrication. The input shaft of the right-angle shaft reducer is horizontally arranged, coaxial with the centerline of the frequency converter motor, allowing for horizontal installation of the frequency converter motor. The output shaft is located on the same axis as the grinding roller shaft.

[0030] A method for modifying a hub-driven grinding device, the method comprising the following steps:

[0031] The original main motor, reducer, grinding disc, hydraulic cylinder, and lower rocker arm of the mill are retained; the original frame is removed and replaced with a hub-driven grinding device, which includes a grinding roller device, upper rocker arm, right-angle shaft reducer, universal coupling, frequency converter motor, and motor support. The upper rocker arm is connected to the original lower rocker arm and hydraulic cylinder.

[0032] The grinding rollers and grinding disc rotate synchronously in opposite directions. The rotational speed of the grinding rollers is adjusted according to the working conditions. The material is actively bitten into the grinding zone on the grinding disc, improving the stability of the material layer. Higher roller pressure can be used to improve the grinding efficiency of the mill. This technology enables the upgrading and transformation of vertical mills to increase production, reduce transformation costs, and improve the performance of vertical mills. It can be applied to existing vertical mills of various types, such as flat disc conical rollers, cup-shaped tire rollers, and flat disc column rollers.

[0033] One or more technical solutions provided in the embodiments of this application have at least the following beneficial effects:

[0034] 1. This invention is an upgrade and transformation of existing traditional vertical mill structures. While retaining the original main motor, main reducer, grinding disc, etc., the original pressurizing device is replaced with a hub-driven grinding device to improve the performance of the mill.

[0035] 2. The vertical mill modification method of the present invention significantly improves grinding efficiency compared with existing vertical mill modification schemes and significantly reduces the cost of replacing roller presses, thus having higher promotion and application value.

[0036] 3. This invention is actually based on a new grinding mechanism. The grinding rollers and grinding disc rotate synchronously in opposite directions, which can use higher roller pressure. The grinding energy is effectively transferred and utilized, making it more energy-efficient than traditional vertical mills.

[0037] 4. The grinding device of the present invention has a certain margin of error. When a variable frequency motor fails, the mill can continue to produce, thereby improving the operating rate of the equipment.

[0038] 5. In this invention, the torsion shaft is located inside the grinding roller bearing. The torsion shaft only bears torque, while the grinding roller shaft only bears bending moment, thus realizing the active rotation of the grinding roller.

[0039] 6. The fixed-axis wheel system of the present invention is located at the front end of the grinding roller, so that the outer diameter of the torque shaft can be as small as possible, and the specifications of the grinding roller shaft and the upper rocker arm can also be as small as possible, so as to construct the hub-driven grinding device at a lower cost.

[0040] 7. The configuration of the grinding roller bearing in this invention is cost-effective. The double-row tapered bearing is installed with negative axial clearance. The grinding roller bearing and the fixed-axis gear train have a common oil chamber, which helps to increase the service life of the grinding roller bearing and the fixed-axis gear train. Attached Figure Description

[0041] The technical solutions of the embodiments of this application will be further described in detail below with reference to the accompanying drawings. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of this application. In addition, unless otherwise specified, these drawings are only intended to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0042] Figure 1 This is an isometric view of a hub-driven grinding device;

[0043] Figure 2 This is the front view of the grinding roller assembly and drive unit;

[0044] Figure 3 This is a front view of a hub-driven grinding device;

[0045] Figure 4 This is a diagram showing the before and after comparison of the renovation;

[0046] Figure 5 This is a sectional view of a right-angle shaft reducer;

[0047] Figure 6 This is an enlarged view of a fixed-axis gear train.

[0048] In the diagram: 1. Roller sleeve, 2. Hub, 3. Double row tapered roller bearing, 4. Cylindrical bearing, 5. Internal gear ring, 6. Planetary gear, 7. Sliding bearing, 8. Spacer ring, 9. Planetary gear pin, 10. Planetary carrier, 11. Sun gear, 12. Torque shaft, 13. Self-aligning bearing, 14. Shaft end cap, 15. Grinding roller shaft, 15a. Oil inlet, 15b. Oil return hole, 16. Thrust self-aligning roller bearing, 17. Upper rocker arm, 18. Lower rocker arm, 19. Rocker arm shaft, 20. Support, 20a. Shaft 21. Bearing seat, 22. Drum-shaped gear coupling, 23. Right-angle shaft reducer, 24. Universal coupling, 25. Variable frequency motor, 26. Motor support, 27. Hydraulic cylinder, 28. Main motor, 29. Reducer, 30. Grinding disc, 30. Bevel gear shaft, 30a. Bevel gear, 31. Pellet gear, 32. Gear shaft, 32a. Pinion, 33. Large gear, 34. Output shaft, 35. Reducer housing, 36. Grinding roller oil level line, C1. Center line of variable frequency motor, C2. Center line of grinding roller. Detailed Implementation

[0049] The hub-driven grinding device includes a grinding roller assembly, a drive unit, a rocker arm assembly, a hydraulic cylinder, and a bracket; the grinding roller assembly includes a roller sleeve, a hub, a grinding roller bearing, and a grinding roller shaft, which are fixedly connected inside the upper rocker arm.

[0050] The drive unit includes a right-angle shaft reducer located at the rear end of the grinding roller and a fixed-axis gear train located at the front end of the grinding roller, which are connected by a torsion shaft located inside the grinding roller; a variable frequency motor fixed on a motor support is connected to the right-angle shaft reducer through a universal coupling, thereby driving the grinding roller device.

[0051] The rocker arm assembly includes an upper rocker arm, a lower rocker arm, and a rocker arm shaft, all fixed within a bearing housing in a bracket. The lower rocker arm is hinged to a hydraulic cylinder, and the grinding roller assembly rotates around the rocker arm shaft under the pulling force of the cylinder, grinding the material on the grinding disc.

[0052] Hub-driven grinding device retrofit method: This method is used to upgrade existing vertical mills. The original main motor, reducer, grinding disc, hydraulic cylinder, and lower rocker arm are retained, while a new grinding device including grinding rollers, upper rocker arm, and hub drive is installed. The grinding rollers and grinding disc rotate synchronously in opposite directions, enabling technological upgrades to increase production capacity, reduce costs, and improve the performance of the vertical mill.

[0053] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0054] Example 1

[0055] The existing vertical mill is upgraded by retaining the original main motor 27, reducer 28, grinding disc 29, hydraulic cylinder 26, and lower rocker arm 18; the original frame is removed and replaced with a hub-driven grinding device, including a grinding roller device, upper rocker arm 17, right-angle shaft reducer 22, universal coupling 23, frequency converter 24, and motor support 25; the upper rocker arm 17 is connected to the original lower rocker arm 18 and hydraulic cylinder 26; the grinding roller and grinding disc 29 rotate synchronously in opposite directions, and the speed of the grinding roller is adjusted according to the working conditions.

[0056] The material is actively bitten into the grinding zone on the grinding disc, improving the stability of the material layer; higher roller pressure can be used to improve the grinding efficiency of the mill; thus realizing the upgrading technology transformation of the vertical mill, reducing costs, and improving the performance of the vertical mill.

[0057] Example 2

[0058] The hub-driven grinding device includes a grinding roller assembly, a drive unit, a rocker arm assembly, a hydraulic cylinder, and a bracket; the grinding roller assembly includes a roller sleeve 1, a hub 2, a grinding roller bearing, and a grinding roller shaft 15, and is fixedly connected inside the upper rocker arm 17.

[0059] The drive unit includes a right-angle reducer 22 located at the rear end of the grinding roller and a fixed-axis gear train located at the front end of the grinding roller. The two are connected by a torsion shaft 12 located inside the grinding roller. A variable frequency motor 24 fixed on a motor support 25 is connected to the right-angle reducer 22 through a universal coupling 23, thereby driving the grinding roller device.

[0060] The rocker arm device includes an upper rocker arm 17, a lower rocker arm 18, and a rocker arm shaft 19, and is fixed in a bearing seat 20a in a bracket 20. The lower rocker arm 18 is hinged to a hydraulic cylinder 26, and the grinding roller device rotates around the rocker arm shaft 19 under the action of the cylinder tension, and grinds the material on the grinding disc 29.

[0061] The grinding roller device is directly driven by a variable frequency motor and is evenly distributed on the grinding disc. By adjusting the motor speed, the grinding rollers and the grinding disc are ensured to rotate synchronously in opposite directions, thereby achieving the optimal operating state of the vertical mill.

[0062] The variable frequency motor 24 is horizontally mounted on the motor support 25, which is made of concrete or steel and connected to the torque shaft 12 via a universal coupling 23, a right-angle shaft reducer 22, and a gear coupling 21. The centerline C1 of the variable frequency motor is arranged at 90° to the centerline C2 of the grinding roller, facilitating the installation and maintenance of the grinding roller and ensuring the motor is installed horizontally. The universal coupling 23 can compensate for the fluctuation of the right-angle shaft reducer 22 during the operation of the grinding roller. The gear coupling 21 can compensate for misalignment during installation and for the deformation of the torque shaft 12 under load, effectively reducing the impact of impact loads on the right-angle shaft reducer 22 and protecting the gears.

[0063] The right-angle shaft reducer 22 consists of a primary bevel gear drive and a secondary parallel shaft drive, including: a bevel gear shaft 30, a bevel gear 31, a gear shaft 32, a large gear 33, and an output shaft 34, all lubricated by an oil bath. A bevel gear 30a is mounted on the bevel gear shaft 30 and meshes with the bevel gear 31 mounted on the gear shaft 32; a small gear 32a is integrally formed on the gear shaft 32 and meshes with the large gear 33 mounted on the output shaft 34; the output shaft 34 is a solid shaft and is connected to a drum-shaped gear coupling 21; the output ends of the bevel gear 31 and the output shaft 34 are located on the same side of the reducer housing 35, facilitating gear lubrication. The bevel gear shaft 30 of the input shaft of the right-angle shaft reducer is horizontally arranged and coaxial with the center line C1 of the variable frequency motor, allowing for horizontal mounting of the variable frequency motor 24; the output shaft 34 is located on the same axis as the grinding roller shaft 15.

[0064] The roller sleeve 1 and the hub 2 are detachably rigidly connected. A grinding roller bearing is provided between the hub 2 and the grinding roller shaft 15. The grinding roller bearing is preferably a double-row tapered bearing 3 and a cylindrical bearing 4, wherein the double-row tapered bearing 3 is located at the large end of the grinding roller and the cylindrical bearing 4 is located at the small end of the grinding roller. This configuration structure has the smallest bearing size and the best cost. The double-row tapered bearing is installed with axial negative clearance, which is beneficial to increasing the service life of the grinding roller bearing and the fixed shaft gear train.

[0065] The grinding roller shaft 15 is equipped with an oil inlet hole 15a and an oil return hole 15b. The grinding roller bearings and the fixed-axis gear train share a common oil chamber. Parts of the grinding roller bearings and the fixed-axis gear train are located below the grinding roller oil level line 36, with approximately one-third of the grinding roller bearings below the oil level. Forced circulation lubrication with thin oil is employed, and a separate lubrication station is configured. Oil enters the chamber through the oil inlet hole 15a on the grinding roller shaft 15, using a high-level oil inlet and low-level oil return method. The circulating oil can remove heat generated during operation and impurities in the oil chamber, extending the service life of the bearings and the fixed-axis gear train.

[0066] The grinding roller shaft 15 is a hollow structure. The torque shaft 12 is fixed inside the grinding roller shaft 15 via a thrust self-aligning roller bearing 16 and a self-aligning bearing 13. The shaft end cover 14 is located at the end of the grinding roller shaft 15, and the self-aligning bearing 13 is installed inside it. This structure facilitates the drive of the hub 2 by the variable frequency motor 24 located outside the mill, thereby realizing the active rotation of the grinding roller. This configuration allows the torque shaft 12 to be rotatably fixed inside the grinding roller shaft 15 and to transmit rotation and torque.

[0067] The fixed-axis gear train is located at the front end of the grinding roller and is a planetary gear transmission with a fixed planetary carrier. A sun gear 11 is located at the end of the torque shaft 12. The shaft end cover 14 is connected to the planetary carrier 10 via three planetary gear pins 9. The planetary gear pins 9 are equipped with spacers 8 for positioning the planetary gears and ensuring gear meshing, sliding bearings 7, and planetary gears 6. The sun gear 11 meshes with all three planetary gears 6 simultaneously. An internal gear ring 5 is installed inside the hub 2 and meshes with all three planetary gears 6 simultaneously. The planetary carrier 10 is fixed relative to the grinding roller shaft 15, and the hub 2 rotates in the opposite direction to the sun gear 11. This configuration allows for a smaller outer diameter of the torque shaft 12, and consequently, smaller specifications for the grinding roller shaft 15, upper rocker arm 17, and fixed-axis gear train, enabling the construction of the hub-driven grinding device at a lower cost.

[0068] The pulling force of the hydraulic cylinder 26 is transmitted to the material on the grinding disc 29 and the grinding disc 29 through the bracket 20, lower rocker arm 18, upper rocker arm 17, grinding roller shaft 15, hub 2, and roller sleeve 1. The grinding roller rotates around the rocker arm shaft 19 under the action of the hydraulic cylinder 26, and compacts and grinds the material on the grinding disc 29. The upper rocker arm 17 can rotate around the rocker arm shaft 19 and can be flipped out from the lower rocker arm 18, which facilitates the installation and maintenance of the grinding roller.

[0069] This technology is used for upgrading existing vertical mills. It retains the original main motor 27, reducer 28, grinding disc 29, hydraulic cylinder 26, and lower rocker arm 18, replacing them with new grinding devices including grinding rollers, upper rocker arm 17, and hub drive unit. It can be applied to existing vertical mills of various types, such as flat disc conical roller, cup-shaped wheel roller, and flat disc column roller, to achieve technological upgrades that increase production capacity, reduce upgrade costs, and improve the performance of the vertical mill.

[0070] In summary, this invention provides a hub-driven grinding device and its modification method, in which the main motor and the variable frequency motor rotate synchronously in opposite directions, improving grinding efficiency and mill output while saving power consumption.

[0071] The above embodiments have provided a detailed description of the present invention, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A hub-driven grinding device, characterized in that: The hub-driven grinding device includes a grinding roller, which is arranged at an angle. A right-angle shaft reducer is located at the rear end of the grinding roller. The right-angle shaft reducer drives a fixed-axis gear train located at the front end of the grinding roller via a torsion shaft inside the grinding roller. The grinding roller shaft is a hollow structure, with no bearing inside the end of the shaft. A self-aligning bearing is installed inside the shaft end cover. The torsion shaft is fixed inside the grinding roller shaft via a thrust self-aligning roller bearing and a self-aligning bearing. The fixed-axis gear train includes a sun gear located at the end of the torsion shaft. The sun gear meshes with planetary gears. The planetary gears are mounted between the shaft end cover and the planet carrier via planetary gear pins. The shaft end cover at the end of the grinding roller shaft is connected to the planet carrier via planetary gear pins. Spacer rings and sliding bearings are provided between the planetary gear pins and the planetary gears. Two spacer rings are located at both ends of the sliding bearings. An internal gear ring is installed inside the hub of the grinding roller, meshing with the planetary gears. The torsion shaft only bears torque, and the grinding roller shaft only bears bending moment. The modification method of the hub-driven grinding device includes the following steps: retaining the original main motor, reducer, grinding disc, hydraulic cylinder, and lower rocker arm of the mill; removing the original frame and replacing it with a hub-driven grinding device, which includes a grinding roller device, an upper rocker arm, a right-angle shaft reducer, a universal coupling, a frequency converter motor, and a motor support. The upper rocker arm is connected to the original lower rocker arm and hydraulic cylinder.

2. The hub-driven grinding device according to claim 1, characterized in that: The grinding roller shaft is provided with an oil inlet hole and an oil return hole. The grinding roller bearing and the fixed shaft gear train have a common oil chamber, that is, some of the grinding roller bearing and the fixed shaft gear train are located below the grinding roller oil level line. The oil chamber adopts thin oil forced circulation lubrication and is equipped with a separate lubrication oil station.

3. The hub-driven grinding device according to claim 1, characterized in that: The grinding disc is driven by the main motor via a speed reducer; The rocker arm assembly includes an upper rocker arm, a lower rocker arm, and a rocker arm shaft, all fixed in a bearing housing within a bracket. The lower rocker arm is hinged to a hydraulic cylinder.

4. The hub-driven grinding device according to claim 1, characterized in that: The grinding roller assembly is fixedly connected inside the upper rocker arm. The grinding roller assembly includes a roller sleeve, a hub, a grinding roller bearing, and a grinding roller shaft. The roller sleeve and the hub are detachably rigidly connected. A grinding roller bearing is provided between the hub and the grinding roller shaft. The grinding roller bearing is a double-row tapered bearing and a cylindrical bearing, wherein the double-row tapered bearing is located at the large end of the grinding roller, and the cylindrical bearing is located at the small end of the grinding roller.

5. The hub-driven grinding device according to claim 1, characterized in that: The right-angle shaft reducer is driven by the frequency converter motor through a universal coupling. The right-angle shaft reducer is connected to the torque shaft through a drum gear coupling. The frequency converter motor is horizontally mounted and fixed on a motor support. The motor support is made of concrete structure. The center line of the frequency converter motor is arranged at 90° with the center line of the grinding roller.

6. The hub-driven grinding device according to claim 1, characterized in that: The right-angle shaft reducer includes: a bevel gear shaft, a bevel gear, a gear shaft, a large gear, and an output shaft. The bevel gear shaft is provided with a bevel gear, which meshes with the bevel gear mounted on the gear shaft. The small gear is integrally formed on the gear shaft and meshes with the large gear mounted on the output shaft. The output shaft is a solid shaft and is connected to a drum-shaped gear coupling.

7. The hub-driven grinding device according to claim 6, characterized in that: The bevel gear and the output end of the output shaft are located on the same side of the reducer housing.

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