Linear permanent magnet motor for ball mill

Abstract

The application relates to the field of ball mill driving devices, in particular to a linear permanent magnet motor for a ball mill. The linear permanent magnet motor for the ball mill comprises a rack, a rotatable ball mill barrel body is arranged on the rack, further comprises: a rotor assembly, the rotor assembly is fixed to the outer circumferential surface of the ball mill barrel body, the rotor assembly comprises a plurality of magnetic steels distributed along the circumference; a stator module, the stator module is two groups, symmetrically arranged on the rack and wrapped outside the rotor assembly, the stator module comprises an annular cover, a stator core fixed in the cover and a stator coil embedded in the stator core; wherein, the inner arc surface of the stator core and the rotor assembly form a working air gap. The linear permanent magnet motor for the ball mill provided by the application directly integrates permanent magnets in the ball mill barrel body to form a rotor, and the stator winding module is symmetrically and non-contactly wrapped outside the rotor, and the barrel body is driven to rotate through the interaction of the rotating magnetic field and the permanent magnetic field.

Description

Technical Field

[0001] This invention relates to the field of ball mill drive equipment, and more particularly to a linear permanent magnet motor for ball mills. Background Technology

[0002] Ball mills are heavy-duty grinding equipment widely used in industries such as mining, metallurgy, building materials and chemicals. They use the rotation of the cylinder to drive the internal grinding media (such as steel balls) to impact and grind materials.

[0003] Currently, the drive system for the ball mill cylinder primarily uses a high-power electric motor as the drive source. Its output shaft is connected to a large reducer (usually a parallel shaft or planetary gear reducer) via a coupling. The reducer converts the high-speed, low-torque output of the motor into a low-speed, high-torque output that meets the process requirements of the ball mill. The reducer's low-speed output shaft then drives a large open gear (large gear ring) fixed to the ball mill cylinder via a rigid or semi-flexible coupling. The motor / reducer assembly then meshes with this large gear ring through a small gear, ultimately transmitting power to the cylinder and driving its rotation.

[0004] As described in patent number 202411071253.8, "A Permanent Magnet Motor for an External Rotor Ball Mill" includes an external rotor and a stator. The stator has a hollow shaft, and a feed pipe for a screw feeder is fixed inside the hollow shaft. The feed pipe passes through the hollow shaft and extends into the ball mill on one side of the permanent magnet motor. The ball mill and the permanent magnet motor are connected by a motor-ball mill connecting flange. The ball mill has a first liner and a second liner. The first liner is fixed to the side of the motor-ball mill connecting flange, and the second liner is fixed to the inner wall of the ball mill cylinder. The beneficial effects of this invention are: the screw feeder enters the ball mill through the hollow shaft permanent magnet motor, the flange, and the end of the ball mill, realizing continuous feeding of the horizontal ball mill without stopping the machine; and the addition of the flange makes it easier to replace the end liner at the feed end of the ball mill, simplifying the structure of the ball mill.

[0005] However, the following defects and shortcomings still exist in the application implementation process: This structure not only suffers from a long and inefficient transmission path, but also exhibits severe wear on the gear pairs under harsh conditions of low speed and heavy load. This necessitates continuous and extensive forced lubrication to maintain operation, resulting in significant oil consumption and on-site pollution. During operation, the periodic meshing impact of the gears generates substantial vibration and noise, further deteriorating the working environment. Furthermore, the structure has numerous components and requires stringent alignment precision; any failure in any part can easily trigger a chain reaction, leading to heavy maintenance workload, high downtime risk, and persistently high operating costs.

[0006] Therefore, it is necessary to provide a new linear permanent magnet motor for ball mills to solve the above-mentioned technical problems. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the present invention provides a linear permanent magnet motor for ball mills.

[0008] The linear permanent magnet motor for ball mills provided by this invention includes a frame, on which a rotatable ball mill cylinder is mounted, and further includes: A rotor assembly is fixed to the outer circumferential surface of the ball mill cylinder, and the rotor assembly includes a plurality of fan-shaped magnets distributed along the circumference. The stator module consists of two sets, symmetrically arranged on the frame and covering the outside of the rotor assembly. The stator module includes an annular outer cover, a stator core fixed inside the outer cover, and stator coils embedded in the stator core. The inner arc surface of the stator core forms a working air gap with the rotor assembly.

[0009] Preferably, two axially distributed retaining rings are fixed on the outer circumferential surface of the ball mill cylinder, and an annular mounting groove is formed between the two retaining rings and the outer wall of the ball mill cylinder. The plurality of magnets are adaptedly embedded and fixed in the mounting groove.

[0010] Preferably, the outer cover is fixed to the frame by a support frame and coaxially sleeved outside the mounting groove. The outer cover has two radially outward protruding sections, and the stator module is installed in the protruding sections.

[0011] Preferably, the stator core is fan-shaped, and multiple stator cores are spliced ​​and fixed along the circumferential direction. Multiple axially extending grooves are opened on the inner arc surface, and the stator coil is embedded and fixed in the grooves. Each stator core has multiple axially distributed blind holes on its inner circumferential surface. A distance sensor is embedded in each blind hole to monitor the distance between the stator core and the rotor assembly in real time.

[0012] Preferably, the protruding section is externally covered with a water cooling system.

[0013] Preferably, the water cooling system includes a water-cooled outer shell that fits against the outer wall of the protruding section. The water-cooled outer shell integrates a main supply pipe, a main return pipe, and multiple branch channels connecting the two. The branch channels are independent and isolated from each other.

[0014] Preferably, the number of the branch channels matches the number of sector partitions divided along the circumference of the stator core, and the flow area of ​​each branch channel corresponds to the position of one of the sector partitions in the circumferential direction.

[0015] Preferably, each of the branch channels is equipped with an independently controlled micro pump at its inlet end to draw coolant from the main supply pipeline and control the flow rate of coolant flowing into the branch channel.

[0016] Preferably, two symmetrically arranged bearing chambers are fixed on the frame, and the main shafts at both ends of the ball mill cylinder are installed in the bearing chambers via heavy roller bearings.

[0017] Compared with related technologies, the linear permanent magnet motor for ball mills provided by this invention has the following advantages: The permanent magnet is directly integrated into the ball mill cylinder to form the rotor. The stator winding module is symmetrically and non-contactly wrapped around the outside of the rotor. The rotation of the cylinder is directly driven by the interaction between the rotating magnetic field and the permanent magnetic field, so as to eliminate the friction loss of all intermediate mechanical transmission links. At the same time, there will be no obvious rigid collision, thus avoiding loud noise.

[0018] By setting up an independent water-cooling circuit corresponding to the stator core and combining it with a real-time air gap monitoring unit, the working air gap can be controlled in real time. When the system operates and the local air gap shrinks abnormally due to uneven temperature, the control system can immediately enhance the cooling intensity of the corresponding area, actively suppress the thermal expansion of the stator at that point, thereby quickly restoring and maintaining the optimal air gap to ensure the high efficiency and safety of the drive system. Attached Figure Description

[0019] Figure 1 A schematic diagram of a preferred embodiment of the linear permanent magnet motor for ball mills provided by the present invention; Figure 2 As shown in this invention Figure 1 A partial structural diagram; Figure 3 This is a schematic diagram of the rotor assembly shown in this invention; Figure 4 This is a schematic diagram of the stator module shown in the present invention; Figure 5 This is a schematic diagram of the water cooling system shown in this invention; Figure 6 This is a schematic diagram of the stator core structure shown in this invention; Figure 7 This is a schematic diagram of the operation process of the water cooling system shown in this invention.

[0020] The following are the labels in the diagram: 1. Frame; 2. Ball mill cylinder; 3. Retaining ring; 4. Mounting groove; 5. Magnet; 6. Support frame; 7. Outer cover; 8. Protruding section; 9. Stator coil; 10. Stator core; 11. Distance sensor; 12. Water-cooled housing; 13. Branch channel. Detailed Implementation

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0026] Please see Figures 1 to 7 This invention provides a linear permanent magnet motor for a ball mill. The linear permanent magnet motor for a ball mill includes a frame 1, on which a rotatable ball mill cylinder 2 is mounted. Specifically, two symmetrically arranged bearing chambers are fixedly mounted on the frame 1. The main shafts at both ends of the ball mill cylinder 2 are mounted in these bearing chambers via heavy roller bearings, thereby achieving stable support for the cylinder and ensuring that it can rotate smoothly around its own axis.

[0027] Two retaining rings 3 are welded and fixed to the outer circumference of the ball mill cylinder 2, which are distributed along the cylinder axis. The outer diameter of the retaining rings 3 is slightly larger than the outer diameter of the ball mill cylinder 2, thus forming an annular mounting groove 4 between the two retaining rings 3 and the outer wall of the ball mill cylinder 2. The rotor assembly is installed inside the mounting groove 4.

[0028] The rotor assembly includes multiple fan-shaped magnets 5 (i.e., permanent magnets). These magnets 5 are tightly assembled into a complete annular magnetic ring according to their magnetization direction (radial magnetization, with adjacent magnets having opposite polarities), and are fitted into the mounting groove 4. The back of each magnet 5 is bolted to the ball mill cylinder 2 to ensure it does not loosen or shift under high-speed rotation and heavy-load conditions.

[0029] An annular outer cover 7 is fixed to the frame 1 via a support frame 6. This outer cover 7 is coaxially fitted onto the outside of the mounting groove 4, maintaining a certain gap with the outer side of the retaining ring 3. The main function of the outer cover 7 is to provide a fully enclosed protection for the mounting groove 4 and the internal magnets 5, isolating them from dust, moisture, and potentially splashed materials generated during the grinding process, and protecting the permanent magnets from contamination and corrosion. The main body of the outer cover 7 is cylindrical, with two symmetrically distributed, radially outward-protruding sections 8, each forming a mounting cavity.

[0030] A stator module is fixedly installed in the mounting cavity of each protruding section 8. The stator module includes a stator core 10 and a stator coil 9. The stator core 10 is formed by stamping and stacking multiple high-permeability silicon steel sheets, and the whole is also fan-shaped. Multiple fan-shaped cores are spliced ​​and fixed along the circumferential direction, and its inner diameter is slightly larger than the outer diameter of the rotor. Multiple axially extending grooves are opened on the inner arc surface of the stator core 10. The stator coil 9 is embedded and fixed in the groove. All coils are connected according to a specific phase sequence (usually three-phase). When three-phase AC power supplied by the frequency converter is applied, a magnetic field rotating uniformly along the circumferential direction is generated in the air gap space inside the stator core 10. This rotating magnetic field interacts with the permanent magnet magnetic field generated by the rotor magnet 5 to generate a continuous tangential electromagnetic force, thereby driving the ball mill cylinder 2 to rotate, realizing direct drive without gears or intermediate transmission components.

[0031] A radial gap, known as the working air gap, is reserved between the inner arc surface of the stator core 10 and the outer surface of the rotor magnet 5. To monitor the uniformity of the air gap in real time, multiple axially distributed blind mounting holes are machined on the inner circumferential surface of each sector-shaped stator core 10. A non-contact distance sensor 11 is embedded inside each blind mounting hole. This allows for real-time and high-precision measurement of the real-time distance between the stator and rotor at corresponding points, and the data is uploaded to the control system.

[0032] A water-cooling system is also installed on the exterior of each protruding section 8 of the outer casing 7. This water-cooling system includes a water-cooled outer shell 12, which fits against the outer wall of the protruding section 8 to form a sealed flow channel space. The water-cooled outer shell 12 integrates a main supply pipe and a main return pipe, as well as multiple completely independent and isolated branch channels 13 connecting the two. The flow area of ​​each branch channel 13 corresponds to the circumferential position of a stator core 10; that is, the number of branch channels 13 matches the number of sections in the stator core 10. Each branch channel 13 is equipped with an independently controlled micro-pump at its inlet to draw coolant from the main supply pipe, precisely controlling the flow rate into that specific channel.

[0033] When the system is running and the temperature rises, the rotor and stator sections have different thermal expansion rates due to differences in materials, heat sources, and heat dissipation conditions. This can lead to a decrease in the air gap in certain areas, directly affecting operational safety and efficiency. In this case, the distance sensor 11 will be the first to detect a decrease in the air gap value in a region corresponding to a certain stator core 10. The control system then activates the micro-pump in the corresponding branch channel 13 to increase the coolant flow rate in that specific channel. This enhanced directional cooling quickly removes heat from the stator core 10 and its coils, suppressing excessive thermal expansion. Conversely, if the air gap increases in a certain area, the cooling intensity can be appropriately reduced to ensure the direct-drive motor always operates in a highly efficient and safe state.

[0034] The specific working principle of this device is as follows: The first step is to power on the entire permanent magnet direct drive system, start the main circulation pump of the control system and water cooling system, ensure that the main supply and return pipelines are unobstructed, and allow the coolant to begin basic circulation. Then, a self-test is performed, recording the initial information measured by each distance sensor 11, and reading and calibrating the current initial air gap value. Afterward, the frequency converter outputs current to the stator coil 9, driving the rotor assembly, composed of the ball mill cylinder 2, retaining ring 3, and magnet 5, to begin slow rotation and smoothly accelerate to the preset operating speed. During this process, the water cooling system maintains basic cooling, and the distance sensors 11 continuously monitor changes in the air gap to ensure smooth startup.

[0035] The second step: Once the ball mill cylinder 2 reaches a stable operating speed, it enters the grinding stage. At this time, the stator coil 9 continuously supplies operating current to generate a rotating magnetic field, driving the cylinder to rotate at a constant speed. Simultaneously, due to electromagnetic losses and heat generated by material grinding, the stator core 10 and rotor assembly begin to heat up. The distance sensors 11 on the inner arc surface of each stator core 10 begin to collect air gap data at their respective points in real time at a higher frequency and transmit the data to the control system in real time.

[0036] The third step: Once the control system analyzes the data from the distance sensor 11 and identifies a sustained abnormal decrease in the air gap value in a region corresponding to a certain sector of the stator core 10 (indicating that the stator's thermal expansion is more pronounced in that region compared to the rotor), the system sends a command to the inlet micro-pump of the independent branch channel 13 corresponding to that stator core 10. The micro-pump responds to the command by increasing the coolant flow rate in that branch, thereby enhancing the cooling intensity of the stator core 10 and its internal coils, quickly dissipating the accumulated heat to suppress excessive thermal expansion, and thus bringing the air gap back to a safe and efficient set range.

[0037] Step 4: When the grinding operation is completed or the machine needs to be stopped, firstly, the inverter is used by the control system to gradually reduce the output current frequency, driving the ball mill cylinder 2 to decelerate smoothly until it stops rotating completely. During the deceleration and shutdown process, the water cooling system continues to run for a period of time to ensure that the stator and rotor assemblies are cooled to near ambient temperature.

[0038] The circuits and controls involved in this invention are all existing technologies and will not be described in detail here.

[0039] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A linear permanent magnet motor for a ball mill, comprising a frame (1) on which a rotatable ball mill cylinder (2) is mounted, characterized in that, Also includes: The rotor assembly is fixed to the outer circumferential surface of the ball mill cylinder (2), and the rotor assembly includes a plurality of fan-shaped magnets (5) distributed along the circumference. The stator module consists of two sets, symmetrically arranged on the frame (1) and covering the outside of the rotor assembly. The stator module includes an annular outer cover (7), a stator core (10) fixed inside the outer cover (7), and a stator coil (9) embedded in the stator core (10). The inner arc surface of the stator core (10) forms a working air gap with the rotor assembly.

2. The linear permanent magnet motor for a ball mill according to claim 1, characterized in that, Two retaining rings (3) are fixed on the outer circumferential surface of the ball mill cylinder (2) and distributed along the axis. The two retaining rings (3) form an annular mounting groove (4) between the two retaining rings (3) and the outer wall of the ball mill cylinder (2). The plurality of magnets (5) are fitted and fixed in the mounting groove (4).

3. The linear permanent magnet motor for a ball mill according to claim 1, characterized in that, The outer cover (7) is fixed to the frame (1) by the support frame (6) and coaxially sleeved outside the mounting groove (4). The outer cover (7) has two radially outward protruding sections (8), and the stator module is installed in the protruding sections (8).

4. The linear permanent magnet motor for a ball mill according to claim 1, characterized in that, The stator core (10) is fan-shaped, and multiple stator cores (10) are spliced ​​and fixed along the circumferential direction. Multiple axially extending grooves are opened on its inner arc surface, and the stator coil (9) is embedded and fixed in the grooves. Each stator core (10) has multiple axially distributed blind holes on its inner circumferential surface. Each blind hole is embedded with a distance sensor (11) for real-time monitoring of the distance between the stator core (10) and the rotor assembly.

5. The linear permanent magnet motor for a ball mill according to claim 3, characterized in that, The protruding section (8) is externally covered with a water cooling system.

6. The linear permanent magnet motor for a ball mill according to claim 5, characterized in that, The water cooling system includes a water cooling shell (12) that is attached to the outer wall of the protruding section (8). The water cooling shell (12) integrates a main supply pipe, a main return pipe and multiple branch channels (13) connected between the two. The branch channels (13) are independent and isolated from each other.

7. The linear permanent magnet motor for a ball mill according to claim 6, characterized in that, The number of the branch channels (13) matches the number of the fan-shaped partitions divided along the circumference of the stator core (10), and the flow area of ​​each branch channel (13) corresponds to the position of one of the fan-shaped partitions in the circumferential direction.

8. The linear permanent magnet motor for a ball mill according to claim 7, characterized in that, Each of the branch channels (13) is equipped with an independently controlled micro pump at its inlet end to draw and control the flow rate of coolant into the branch channel (13) from the main supply line.

9. The linear permanent magnet motor for a ball mill according to claim 1, characterized in that, Two symmetrically arranged bearing chambers are fixed on the frame (1), and the main shafts at both ends of the ball mill cylinder (2) are installed in the bearing chambers through heavy roller bearings.

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