A medium-speed coal mill with permanent magnet variable loading force

Abstract

An embodiment of the present disclosure provides a permanent magnetic variable loading force medium-speed coal mill, comprising: a grinding barrel; a permanent magnetic variable loading force control device, arranged in the grinding barrel; a grinding disc, arranged in the grinding barrel; a grinding roller, arranged in the grinding barrel, and the grinding roller and the permanent magnetic variable loading force control device are arranged correspondingly; wherein the permanent magnetic variable loading force control device is used to provide an adjustable loading force and act on the grinding roller to adjust the pressing force between the grinding roller and the grinding disc. In the present disclosure, an adjustable loading force is provided by the permanent magnetic variable loading force control device, thereby adjusting the pressing force between the grinding roller and the grinding disc. The permanent magnetic variable loading force control device can accurately control the pressing force between the grinding roller and the grinding disc, thereby optimizing the coal grinding process and improving the coal grinding efficiency.

Description

Technical Field

[0001] The embodiments of the present disclosure belong to the technical field of medium-speed coal mills for coal-fired power station boilers, and particularly relate to a permanent magnet variable loading force medium-speed coal mill. Background Art

[0002] The pulverizing system is one of the most important auxiliary equipment of coal-fired power units. The coal required for boiler combustion is dried and ground into suitable particle size through the pulverizing system and then transported to the combustion system for the next reaction.

[0003] Medium-speed coal mill systems are currently the most widely used type of coal pulverizing system in power plant boilers. A medium-speed coal mill requires sufficient loading force on the internal grinding rollers to ensure that the raw coal trapped between the rollers and the grinding discs is ground into qualified pulverized coal for external supply. Existing medium-speed coal mills use either hydraulic or spring systems to provide loading force, and both types have extensive application experience.

[0004] However, for spring-loaded medium-speed coal mills, the non-adjustable nature of the springs forces the mill to operate under fixed loading conditions, significantly reducing its adjustability. For hydraulically loaded medium-speed coal mills, pressure in the hydraulic system is transmitted via tie rods and mechanical mechanisms, leading to frequent tie rod breakage, impacting equipment stability.

[0005] In response to the practical problems existing in the above-mentioned equipment, designing a variable loading system that can be flexibly adjusted and has stable operation is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art and provide a permanent magnet variable loading force medium speed coal mill.

[0007] One aspect of an embodiment of the present disclosure provides a permanent magnet variable loading force medium speed coal mill, comprising: a grinding drum;

[0008] A permanent magnet variable loading force control device is provided on the grinding cylinder;

[0009] a grinding disc, disposed in the grinding cylinder;

[0010] A grinding roller is arranged in the grinding cylinder, and the grinding roller is arranged corresponding to the permanent magnetic variable loading force control device;

[0011] The permanent magnet variable loading force control device is used to provide an adjustable loading force and act on the grinding roller to adjust the pressing force between the grinding roller and the grinding disc.

[0012] Optionally, the permanent magnet variable loading force control device includes a rotating mechanism and a permanent magnet magnetic assembly kit;

[0013] The rotating mechanism is rotatably connected to the wall of the grinding cylinder, and the rotating mechanism has an annular cavity;

[0014] The permanent magnet assembly kit includes a static permanent magnet kit and a dynamic permanent magnet kit; along the radial direction of the grinding cylinder, the static permanent magnet kit can be slidably arranged on the cylinder wall of the grinding cylinder and corresponds to the position of the grinding roller; the dynamic permanent magnet kit is arranged on the inner wall of the annular cavity and is arranged opposite to the static permanent magnet kit with the same pole;

[0015] According to the magnetic repulsion generated by the same poles of the dynamic permanent magnet set and the static permanent magnet set being arranged opposite to each other, the static permanent magnet set is moved radially along the grinding cylinder and drives the grinding roller to move, so as to adjust the pressing force between the grinding roller and the grinding disc.

[0016] Optionally, the rotating mechanism includes a rotating drum and an adjusting member provided on the rotating drum; the rotating drum has the annular cavity;

[0017] The outer wall of the grinding cylinder is provided with a guide rail; the end of the rotating cylinder close to the wall of the grinding cylinder is provided with a slide groove adapted to the guide rail; the rotating cylinder and the grinding cylinder are rotatably connected by the adapted installation of the slide groove and the guide rail;

[0018] The adjusting member is used to drive the rotating drum to rotate on the grinding drum, so as to adjust the magnetic repulsion between the moving permanent magnet set and the static permanent magnet set.

[0019] Optionally, the static permanent magnet kit includes a static permanent magnet group, a sliding cylinder and an abutment member; a sliding hole is provided on the cylinder wall of the grinding cylinder;

[0020] The slide cylinder is passed through the slide hole, the static permanent magnet group is provided at the first end of the slide cylinder, and the abutment is provided at the second end of the slide cylinder; the abutment is used to abut against the grinding roller;

[0021] The slide cylinder moves in the radial direction of the grinding cylinder according to the magnetic repulsion force, so that the abutment member abuts against the grinding roller to adjust the pressing force between the grinding roller and the grinding disc.

[0022] Optionally, there are multiple moving permanent magnet sets; around the axial direction of the rotating drum, multiple moving permanent magnet sets are arranged on the inner wall of the annular cavity at intervals;

[0023] There are multiple static permanent magnet groups; around the axial direction of the slide cylinder, multiple static permanent magnet groups are arranged in a ring at intervals on the first end of the slide cylinder;

[0024] Wherein, the plurality of moving permanent magnet kits and the plurality of static permanent magnet groups are arranged in one-to-one correspondence.

[0025] Optionally, the moving permanent magnet set is in a bar shape, and the moving permanent magnet set includes a first moving magnet group and a second moving magnet group that are arranged opposite to each other;

[0026] The first moving magnet group and the second moving magnet group respectively include a plurality of moving permanent magnets arranged along the length direction of the moving permanent magnet set.

[0027] Optionally, along the length direction of the moving permanent magnet set, the width dimensions of the moving permanent magnet set are equal; correspondingly, the magnetic moments between the moving permanent magnets of the first moving magnetic group and the moving permanent magnets of the second moving magnetic group gradually increase.

[0028] Optionally, along the length direction of the moving permanent magnet set, the spacing between the first moving magnetic group and the second moving magnetic group is equal; the width dimensions of the plurality of moving permanent magnets corresponding to the first moving magnetic group and the second moving magnetic group are gradually reduced.

[0029] Optionally, the repulsive force between the static permanent magnet kit and the dynamic permanent magnet kit satisfies the conditional formula:

[0030] f(M j ,M dp ,r)=k×(M j ×M dp ) / r 2 ,

[0031] Among them, f(M j ,M dp , r) is the magnetic repulsion between the dynamic permanent magnet suite and the static permanent magnet suite, r is the distance between the dynamic permanent magnet suite and the static permanent magnet suite, k is the magnetic repulsion constant, M j is the effective magnetic moment of the static permanent magnet set, M dp is the effective magnetic moment of the moving permanent magnet kit;

[0032] Among them, the constraint condition is: 0.8×F min ≤f(M j ,M dp ,r)≤1.5×F max , design the static permanent magnet kit M j The effective magnetic moment range.

[0033] Optionally, the repulsive force between the static permanent magnet set and the dynamic permanent magnet set

[0034] Satisfy the conditions:

[0035] f(M j ,M dp ,r+h)=k×(Mj ×M dp ) / (r+h) 2 ,

[0036] Among them, f(M j ,M dp , r+h) is the magnetic repulsion between the dynamic permanent magnet set and the static permanent magnet set, r is the distance between the dynamic permanent magnet set and the static permanent magnet set, h is the distance between the grinding roller and the grinding disc, k is the magnetic repulsion constant, M j is the effective magnetic moment of the static permanent magnet set, M dp is the effective magnetic moment of the moving permanent magnet kit;

[0037] Among them, the constraint condition is: 0.6×F min ≤f(M j ,M dp ,r+h)≤

[0038] 1.1×F max , design the M of the moving permanent magnet kit dp The effective magnetic moment range and the width size of a single moving magnet.

[0039] The beneficial effects of the embodiments of the present disclosure include:

[0040] In the present disclosure, an adjustable loading force is provided by a permanent magnetic variable loading force control device, thereby adjusting the pressing force between the grinding roller and the grinding disc. The permanent magnetic variable loading force control device can accurately control the pressing force between the grinding roller and the grinding disc, thereby optimizing the coal grinding process and improving the coal grinding efficiency. In addition, the loading force can be flexibly adjusted according to different coal types and working conditions to ensure that the coal mill operates in the best condition. By accurately controlling the pressing force, excessive wear of the grinding roller and the grinding disc caused by excessive pressure can be avoided, thereby extending the service life of the equipment. And a reasonable distribution of loading force can make the wear of the grinding roller and the grinding disc more uniform, further extending the service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a structural schematic diagram of a permanent magnet variable loading force medium speed coal mill according to an embodiment of the present disclosure;

[0042] Figure 2 This is a structural diagram of a permanent magnet variable loading force control device according to an embodiment of the present disclosure;

[0043] Figure 3 This is a partial structural diagram of a static permanent magnet kit according to an embodiment of the present disclosure;

[0044] Figure 4 Schematic diagram of the structure of a moving permanent magnet kit according to an embodiment of the present disclosure.

[0045] In the figure, 1. grinding cylinder; 2. permanent magnet variable loading force control device; 3. grinding disc; 4. grinding roller; 11. guide rail; 21. rotating mechanism; 22. static permanent magnet kit; 23. dynamic permanent magnet kit; 211. rotating cylinder; 212. adjusting member; 213. annular cavity; 221. static permanent magnet group; 222. sliding cylinder; 223. abutment member; 231. first dynamic magnet group; 232. second dynamic magnet group; 233. dynamic permanent magnet. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0047] The following is a further detailed description of the embodiments of the present application in conjunction with the accompanying drawings and examples. The detailed descriptions and drawings of the following examples are used to illustrate the principles of the present application, but are not used to limit the scope of the present application, that is, the present application is not limited to the described embodiments. In the description of the present application, it should be noted that, unless otherwise specified, the meaning of "multiple" is more than two; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inside", "outside", etc. is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not perpendicular in the strict sense, but is within the allowable error range. "Parallel" is not parallel in the strict sense, but is within the allowable error range.

[0048] It should also be noted that, in the description of this application, unless otherwise specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0049] like Figure 1-4 As shown, a permanent magnetic variable loading force medium-speed coal mill comprises a grinding drum 1, a permanent magnetic variable loading force control device 2, a grinding disc 3, and a grinding roller 4. The permanent magnetic variable loading force control device 2 is disposed in the grinding drum 1, the grinding disc 3 is disposed within the grinding drum 1, and the grinding roller 4 is disposed within the grinding drum 1, with the grinding roller 4 being disposed corresponding to the permanent magnetic variable loading force control device 2.

[0050] The permanent magnet variable loading force control device 2 is used to provide an adjustable loading force and act on the grinding roller 4 to adjust the pressing force between the grinding roller 4 and the grinding disc 3 .

[0051] In the present disclosure, an adjustable loading force is provided by a permanent magnetic variable loading force control device 2, thereby adjusting the pressing force between the grinding roller 4 and the grinding disc 3. Through the permanent magnetic variable loading force control device 2, the pressing force between the grinding roller 4 and the grinding disc 3 can be accurately controlled, thereby optimizing the coal grinding process and improving the coal grinding efficiency. In addition, the loading force can be flexibly adjusted according to different coal types and working conditions to ensure that the coal mill operates in the best state. By accurately controlling the pressing force, excessive wear of the grinding roller 4 and the grinding disc 3 caused by excessive pressure can be avoided, thereby extending the service life of the equipment. And a reasonable distribution of loading force can make the wear of the grinding roller 4 and the grinding disc 3 more uniform, further extending the service life of the equipment.

[0052] In some embodiments, the permanent magnet variable loading force control device 2 includes a rotating mechanism 21 and a permanent magnet assembly. The rotating mechanism 21 is rotatably connected to the wall of the grinding cylinder 1 and has an annular cavity 213 .

[0053] The permanent magnet assembly includes a static permanent magnet assembly 22 and a dynamic permanent magnet assembly 23. Along the radial direction of the grinding cylinder 1, the static permanent magnet assembly 22 is slidably arranged on the wall of the grinding cylinder 1 and corresponds to the position of the grinding roller 4. The dynamic permanent magnet assembly 23 is arranged on the inner wall of the annular cavity 213 and is arranged opposite to the static permanent magnet assembly 22 with the same pole.

[0054] Among them, according to the magnetic repulsion generated by the same-pole relative arrangement of the dynamic permanent magnet set 23 and the static permanent magnet set 22, the static permanent magnet set 22 is moved radially along the grinding cylinder 1 and drives the grinding roller 4 to move, so as to adjust the pressing force between the grinding roller 4 and the grinding disc 3.

[0055] In the present disclosure, the magnetic repulsion between the dynamic permanent magnet assembly 23 and the static permanent magnet assembly 22 allows precise control of the compressive force between the grinding roller 4 and the grinding disc 3, thereby achieving fine-tuning of the coal grinding process. The stability and adjustability of the magnetic repulsion ensures stable operation of the coal mill under various operating conditions, improving the precision and consistency of coal grinding. Precise control of the magnetic repulsion prevents excessive wear of the grinding roller 4 and grinding disc 3 due to excessive pressure, thereby extending the service life of the equipment.

[0056] In some embodiments, the rotating mechanism 21 includes a rotating drum 211 and an adjusting member 212 disposed on the rotating drum 211 , and the rotating drum 211 has the annular cavity 213 .

[0057] The outer wall of the grinding cylinder 1 is provided with a guide rail 11, and the end of the rotating cylinder 211 close to the cylinder wall of the grinding cylinder 1 is provided with a slide groove adapted to the guide rail 11. The rotating cylinder 211 and the grinding cylinder 1 are rotationally connected through the adaptation installation of the slide groove and the guide rail 11.

[0058] The adjusting member 212 is used to drive the rotating drum 211 to rotate on the grinding drum 1 , so as to adjust the magnetic repulsion between the moving permanent magnet set 23 and the static permanent magnet set 22 .

[0059] In the present disclosure, the relative position between the dynamic permanent magnet assembly 23 and the static permanent magnet assembly 22 can be precisely adjusted by driving the rotating drum 211 to rotate by the adjusting member 212, thereby precisely controlling the magnitude of the magnetic repulsion. The design of the rotating mechanism 21 allows for continuous adjustment, making the adjustment of the magnetic repulsion more flexible and precise.

[0060] Furthermore, by precisely controlling the magnetic repulsion force, it is possible to ensure that the pressing force between the grinding roller 4 and the grinding disc 3 is always maintained within an optimal range, thereby improving the accuracy and stability of coal grinding.

[0061] In some embodiments, the static permanent magnet assembly 22 includes a static permanent magnet group 221 , a sliding cylinder 222 and an abutment member 223 , and a sliding hole is provided on the cylinder wall of the grinding cylinder 1 .

[0062] The slide cylinder 222 is passed through the slide hole. The static permanent magnet group 221 is provided at the first end of the slide cylinder 222 . The abutment member 223 is provided at the second end of the slide cylinder 222 . The abutment member 223 is used to abut against the grinding roller 4 .

[0063] The slide cylinder 222 moves in the radial direction of the grinding cylinder 1 according to the magnetic repulsion force, so that the abutment member 223 abuts against the grinding roller 4 to adjust the pressing force between the grinding roller 4 and the grinding disc 3 .

[0064] In this disclosure, the design of the slide 222 and abutment 223 allows precise control of the position of the static permanent magnet assembly 221, thereby accurately adjusting the compressive force between the grinding roller 4 and the grinding disc 3. The slide 222 moves radially within the grinding drum 1 in response to the magnetic repulsion force, rapidly responding to changes in the magnetic repulsion force and ensuring timely adjustment of the position of the grinding roller 4. The design of the slide 222 and abutment 223 ensures that the compressive force between the grinding roller 4 and the grinding disc 3 remains within an optimal range, improving the accuracy and stability of coal grinding.

[0065] In some embodiments, there are multiple moving permanent magnet sets 23 , which are arranged on the inner wall of the annular cavity 213 at intervals around the axial direction of the rotating cylinder 211 .

[0066] There are multiple static permanent magnet groups 221 axially arranged around the slide cylinder 222 , and the multiple static permanent magnet groups 221 are arranged at intervals in a ring at the first end of the slide cylinder 222 .

[0067] The plurality of moving permanent magnet sets 23 and the plurality of static permanent magnet groups 221 are arranged in a one-to-one correspondence.

[0068] In this disclosure, the annular arrangement of multiple dynamic permanent magnet assemblies 23 and multiple static permanent magnet groups 221 ensures uniform distribution of magnetic force along the radial direction of the grinding drum 1, avoiding the problem of excessive or weak local magnetic force. This uniform magnetic force distribution ensures a more uniform pressing force between the grinding roller 4 and the grinding disc 3, improving the consistency and stability of the coal grinding process.

[0069] The corresponding arrangement of the plurality of moving permanent magnet sets 23 and the static permanent magnet group 221 makes the adjustment of the magnetic force more precise, and the relative position of each magnet can be flexibly adjusted as needed, thereby achieving fine control of the pressing force.

[0070] In some embodiments, the moving permanent magnet set 23 is in a bar shape, and the moving permanent magnet set 23 includes a first moving magnet group 231 and a second moving magnet group 232 that are oppositely arranged.

[0071] The first moving magnet group 231 and the second moving magnet group 232 each include a plurality of moving permanent magnets 233 arranged along the length direction of the moving permanent magnet assembly 23 .

[0072] In the present disclosure, the first moving magnetic group 231 and the second moving magnetic group 232 respectively include a plurality of moving permanent magnets 233 arranged along the length direction of the moving permanent magnet set 23. This layout ensures the uniform distribution of magnetic force in the radial direction of the grinding cylinder 1, avoiding the problem of local magnetic force being too strong or too weak.

[0073] The uniform magnetic force distribution makes the pressing force between the grinding roller 4 and the grinding disc 3 more uniform, thereby improving the consistency and stability of the coal grinding process.

[0074] The arrangement of the plurality of moving permanent magnets 233 allows for more precise adjustment of the magnetic force, and the relative position of each moving permanent magnet 233 can be flexibly adjusted as needed, thereby achieving fine control of the pressing force.

[0075] In some embodiments, along the length direction of the moving permanent magnet set 23, the width of the moving permanent magnet set 23 is equal, and the magnetic moments between the moving permanent magnets 233 of the first moving magnet group 231 and the moving permanent magnets 233 of the second moving magnet group 232 are gradually increased. Figure 4 , pointing upward along the moving permanent magnet kit 23 from left to right.

[0076] In the present disclosure, the widths of the plurality of moving permanent magnets 233 corresponding to the first moving magnet group 231 and the second moving magnet group 232 are tapered. This design ensures a more uniform distribution of magnetic force along the length of the moving permanent magnet assembly 23. The tapered width design reduces excessive concentration of magnetic force in certain areas, thus avoiding uneven compaction caused by excessive localized magnetic force.

[0077] The tapered width dimension design makes the magnetic force contribution of each moving permanent magnet 233 more balanced, and the relative position of each moving permanent magnet 233 can be flexibly adjusted as needed, thereby achieving fine control of the pressing force.

[0078] In some embodiments, the first moving magnet group 231 and the second moving magnet group 232 are spaced evenly apart along the length of the moving permanent magnet assembly 23. The widths of the moving permanent magnets 233 corresponding to the first moving magnet group 231 and the second moving magnet group 232 are gradually reduced.

[0079] In the present disclosure, the widths of the plurality of moving permanent magnets 233 corresponding to the first moving magnet group 231 and the second moving magnet group 232 are tapered. This design ensures a more uniform distribution of magnetic force along the length of the moving permanent magnet assembly 23. The tapered width design reduces excessive concentration of magnetic force in certain areas, thus avoiding uneven compaction caused by excessive localized magnetic force.

[0080] The tapered width dimension design makes the magnetic force contribution of each moving permanent magnet 233 more balanced, and the relative position of each moving permanent magnet 233 can be flexibly adjusted as needed, thereby achieving fine control of the pressing force.

[0081] In some embodiments, the static permanent magnet group 221 is in a bar shape. Along the length direction of the static permanent magnet group 221 , the static permanent magnet group 221 includes a plurality of static permanent magnets arranged at equal intervals.

[0082] In some embodiments, the repulsive force between the static permanent magnet assembly and the dynamic permanent magnet assembly satisfies the conditional formula:

[0083] f(M j ,M dp ,r)=k×(M j ×M dp ) / r 2 ,

[0084] Among them, f(M j ,M dp , r) is the magnetic repulsion between the dynamic permanent magnet suite and the static permanent magnet suite, r is the distance between the dynamic permanent magnet suite and the static permanent magnet suite, k is the magnetic repulsion constant, M j is the effective magnetic moment of the static permanent magnet set, M dp is the effective magnetic moment of the moving permanent magnet set.

[0085] Among them, the constraint condition is: 0.8×F min ≤f(M j ,M dp ,r)≤1.5×F max , design the static permanent magnet kit M jThe effective magnetic moment range.

[0086] In some embodiments, the repulsive force between the static permanent magnet assembly and the dynamic permanent magnet assembly satisfies the conditional formula:

[0087] f(M j ,M dp ,r+h)=k×(M j ×M dp ) / (r+h) 2 ,

[0088] Among them, f(M j ,M dp , r+h) is the magnetic repulsion between the dynamic permanent magnet set and the static permanent magnet set, r is the distance between the dynamic permanent magnet set and the static permanent magnet set, h is the distance between the grinding roller and the grinding disc, k is the magnetic repulsion constant, M j is the effective magnetic moment of the static permanent magnet set, M dp is the effective magnetic moment of the moving permanent magnet set.

[0089] Among them, the constraint condition is: 0.6×F min ≤f(M j ,M dp ,r+h)≤1.1×F max , design the M of the moving permanent magnet kit dp The effective magnetic moment range and the width size of a single moving magnet.

[0090] A specific example provided by the present disclosure includes:

[0091] The coal mill includes a permanent magnet variable loading force control device, which is used to adjust and control the pressing force between the grinding roller and the grinding disc in the coal mill.

[0092] The permanent magnet variable load force control device includes a rotating mechanism and a permanent magnet magnetic assembly, as well as an adjustment mechanism (i.e., an adjustment member) arranged on the rotating mechanism. The permanent magnet magnetic assembly includes a moving permanent magnet assembly and a static permanent magnet assembly with the same polarity opposite to each other, wherein a magnetic repulsion force is generated between the two permanent magnets with the same polarity opposite to each other. The adjustment mechanism is used to adjust the rotation angle of the rotating mechanism, thereby adjusting the rotation position of the moving permanent magnet assembly. The magnetic moments between the permanent magnets on the moving permanent magnet assembly at different positions are different, thereby generating different same-polarity magnetic repulsion forces with the static permanent magnet assembly.

[0093] The rotating mechanism is used to evenly distribute the magnetic repulsion between the moving and static permanent magnets. Specifically, it is a rigid rotating mechanism. The rigidity of the rotating mechanism provides mechanical support, ensuring that the radial position of the moving permanent magnet relative to the mill wall remains unchanged.

[0094] Multiple sets of dynamic permanent magnets are evenly arranged along the circumference of the rotating mechanism (matching the number of grinding rollers) and fixed to the inner wall of the rotating mechanism's annular cavity. These sets rotate along the grinding drum along with the rotating mechanism. The static permanent magnets are slidably connected to the mill drum wall (matching the number and position of the static permanent magnets as the grinding rollers) and can move radially along the mill drum wall.

[0095] The dynamic permanent magnet set and the static permanent magnet set are arranged opposite to each other with the same poles in the diameter direction of the coal mill cylinder wall. During the rotation adjustment process of the dynamic permanent magnet set, a partial magnetic group with the same area as the static permanent magnet set is always maintained to cooperate with the static magnetic group to generate magnetic repulsion.

[0096] Multiple sets of dynamic permanent magnets are evenly spaced along the circumference of the rotating mechanism (matching the number of grinding rollers). They are fixedly connected to the inner wall of the rotating mechanism's annular cavity and can rotate along the mill barrel with the rotating mechanism. Static permanent magnets are slidably connected to the mill barrel (matching the number and position of the grinding rollers) and can move radially along the mill barrel. The dynamic and static permanent magnets are positioned opposite each other in the radial direction of the mill barrel, with the same polarity.

[0097] An annular guide rail is provided on the outer side of the cylinder wall of the coal mill, and the rotating mechanism has a slide groove adapted to the guide rail. The rotating mechanism utilizes the slide groove to rotate along the guide rail around the cylinder wall. An adjusting part is installed at the lower part of the rotating mechanism, and the adjusting part drives the rotating mechanism to rotate.

[0098] refer to Figure 4 The moving permanent magnet kit is designed as a variable magnetic moment strip structure, which includes a first moving magnet group and a second moving magnet group arranged relatively to each other. The width dimension of the moving permanent magnet kit remains unchanged, and the width dimension of the moving magnet gradually decreases from one end to the other end of the moving permanent magnet kit, that is, the magnetic moment gradually increases (decreases). In order to ensure that the rotating structure is subjected to uniform force, the moving magnet group adopts an end-to-end arrangement structure. Along the circumferential (incomplete) direction of the moving magnet group, the area of ​​the middle area where the moving magnet is not installed increases (decreases) successively, and the area where the moving magnet is installed is designed to have equal width in the vertical width direction. In addition, the moving magnet group can also be designed according to a design method in which the width of the magnets at different positions is equal, but the effective magnetic moment gradually changes, that is, along the direction of the moving magnet, under the condition of the same magnet surface area, the effective magnetic moment gradually increases (decreases).

[0099] refer to Figure 3 In some embodiments, the static magnetic group is designed as a fixed magnetic moment structure.

[0100] In some embodiments, the size of the moving magnet group is larger than the size of the static magnet group.

[0101] The rotating structure is a cylindrical structure, and the dynamic permanent magnet sets are evenly arranged on the inner surface of the cylinder. The magnetic repulsion generated between each group of corresponding dynamic permanent magnet sets and static permanent magnet sets is equal and evenly distributed on the wall of the cylinder. All magnetic repulsion forces act along the normal direction of the cylinder wall (the axial direction of the cylinder), thereby compensating each other and not generating forces in other directions of the cylinder.

[0102] As the rigid structure rotates, the magnetic repulsion between the dynamic permanent magnet assembly and the static permanent magnet assembly changes due to the variable magnetic moment design of the dynamic permanent magnet assembly, but the rotating structure can always maintain radial force balance.

[0103] As the moving permanent magnet assembly rotates synchronously under the pull of the adjusting element, its variable magnetic moment design causes its effective magnetic moment to change, resulting in a corresponding change in the magnetic repulsion between it and the static permanent magnet assembly. The greater the effective magnetic moment of the moving permanent magnet assembly directly opposite the static permanent magnet assembly, the greater the magnetic repulsion between the moving and static permanent magnet assembly. This results in a greater force transmitted from the static permanent magnet assembly to the grinding roller, which in turn transmits a greater force to the grinding disc, resulting in a greater loading force on the coal mill. Conversely, a smaller loading force on the coal mill decreases.

[0104] The designed working distance between the dynamic permanent magnet set and the static permanent magnet set is r, the distance between the grinding roller and the grinding disc is h, and the minimum loading force during the coal mill startup phase is F min The maximum load force of the coal mill is F max , the effective magnetic moment of the static permanent magnet set is M j , the effective magnetic moment of the moving permanent magnet set is M dp , system design constraint 1 is:

[0105] 0.8×F min ≤f(M j ,M dp ,r)≤1.5×F max

[0106] Design M according to constraint 1 j ;

[0107] Constraint 2 of the system design is:

[0108] 0.6×F min ≤f(M j ,M dp ,r+h)≤1.1×F max

[0109] Design M according to constraint 2 dp The effective magnetic moment range and the width size of a single moving magnet.

[0110] The loading force adjustment is performed according to a step-by-step variable loading force strategy. The angle of each rotation of the adjustment mechanism is guaranteed to span at least one minimum permanent magnet unit. Based on this constraint, the width of the minimum permanent magnet unit and the single-step adjustment angle of the actuator are reasonably designed.

[0111] It is understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present disclosure, and the present disclosure is not limited thereto. Those skilled in the art may make various modifications and improvements without departing from the spirit and substance of the present disclosure, and such modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A permanent magnet variable loading medium speed coal mill, characterized in that: include: grinding cylinder; A permanent magnet variable loading force control device is provided on the grinding cylinder; a grinding disc, disposed in the grinding cylinder; A grinding roller is arranged in the grinding cylinder, and the grinding roller is arranged corresponding to the permanent magnetic variable loading force control device; The permanent magnet variable loading force control device is used to provide an adjustable loading force and act on the grinding roller to adjust the pressing force between the grinding roller and the grinding disc; The permanent magnet variable loading force control device includes a rotating mechanism and a permanent magnet magnetic assembly kit; The rotating mechanism is rotatably connected to the wall of the grinding cylinder, and the rotating mechanism has an annular cavity; The permanent magnet assembly kit includes a static permanent magnet kit and a dynamic permanent magnet kit; along the radial direction of the grinding cylinder, the static permanent magnet kit can be slidably arranged on the cylinder wall of the grinding cylinder and corresponds to the position of the grinding roller; the dynamic permanent magnet kit is arranged on the inner wall of the annular cavity and is arranged opposite to the static permanent magnet kit with the same pole; According to the magnetic repulsion generated by the same poles of the dynamic permanent magnet set and the static permanent magnet set being arranged opposite to each other, the static permanent magnet set is moved radially along the grinding cylinder and drives the grinding roller to move, so as to adjust the pressing force between the grinding roller and the grinding disc.

2. A permanent magnet variable loading force medium speed coal mill according to claim 1, characterized in that: The rotating mechanism includes a rotating drum and an adjusting member provided on the rotating drum; the rotating drum has the annular cavity; The outer wall of the grinding cylinder is provided with a guide rail; the end of the rotating cylinder close to the wall of the grinding cylinder is provided with a slide groove adapted to the guide rail; the rotating cylinder and the grinding cylinder are rotatably connected by the adapted installation of the slide groove and the guide rail; The adjusting member is used to drive the rotating drum to rotate on the grinding drum, so as to adjust the magnetic repulsion between the moving permanent magnet set and the static permanent magnet set.

3. The permanent magnet variable loading medium speed coal mill according to claim 2, characterized in that: The static permanent magnet kit includes a static permanent magnet group, a sliding cylinder and an abutment member; a sliding hole is provided on the cylinder wall of the grinding cylinder; The slide cylinder is passed through the slide hole, the static permanent magnet group is provided at the first end of the slide cylinder, and the abutment is provided at the second end of the slide cylinder; the abutment is used to abut against the grinding roller; The slide cylinder moves in the radial direction of the grinding cylinder according to the magnetic repulsion force, so that the abutment member abuts against the grinding roller to adjust the pressing force between the grinding roller and the grinding disc.

4. The permanent magnet variable loading medium speed coal mill according to claim 3, characterized in that: There are multiple moving permanent magnet sets; around the axial direction of the rotating drum, multiple moving permanent magnet sets are arranged on the inner wall of the annular cavity at intervals; There are multiple static permanent magnet groups; around the axial direction of the slide cylinder, multiple static permanent magnet groups are arranged in a ring at intervals on the first end of the slide cylinder; Wherein, the plurality of moving permanent magnet kits and the plurality of static permanent magnet groups are arranged in one-to-one correspondence.

5. The permanent magnet variable loading medium speed coal mill according to claim 1, characterized in that: The moving permanent magnet set is in a bar shape, and comprises a first moving magnet group and a second moving magnet group that are arranged opposite to each other; The first moving magnet group and the second moving magnet group respectively include a plurality of moving permanent magnets arranged along the length direction of the moving permanent magnet set.

6. The permanent magnet variable loading medium speed coal mill according to claim 5, characterized in that: Along the length direction of the moving permanent magnet set, the width dimensions of the moving permanent magnet set are equal; the width dimensions of the moving permanent magnets corresponding to the first moving magnet group and the second moving magnet group are gradually reduced.

7. The permanent magnet variable loading medium speed coal mill according to claim 5, characterized in that: Along the length direction of the moving permanent magnet set, the distances between the first moving magnetic group and the second moving magnetic group are equal; correspondingly, the magnetic moments between the moving permanent magnets of the first moving magnetic group and the moving permanent magnets of the second moving magnetic group gradually increase.

8. The permanent magnet variable loading medium speed coal mill according to claim 1, characterized in that: The repulsive force between the static permanent magnet set and the dynamic permanent magnet set satisfies the conditional formula: f(M j , M dp , r)=k×(M j ×M dp ) / r 2 , Among them, f(M j , M dp , r) is the magnetic repulsion between the dynamic permanent magnet set and the static permanent magnet set, r is the distance between the dynamic permanent magnet set and the static permanent magnet set, k is the magnetic repulsion constant, M j is the effective magnetic moment of the static permanent magnet set, M dp is the effective magnetic moment of the moving permanent magnet kit; Among them, the constraint condition is: 0.8×F min ≤ f(M j , M dp , r) ≤ 1.5×F max , design the static permanent magnet kit M j The effective magnetic moment range.

9. The permanent magnet variable loading medium speed coal mill according to claim 1, characterized in that: The repulsive force between the static permanent magnet set and the dynamic permanent magnet set satisfies the conditional formula: f(M j , M dp , r+h)=k×(M j ×M dp ) / (r+h) 2 , Among them, f(M j , M dp , r+h) is the magnetic repulsion between the dynamic permanent magnet set and the static permanent magnet set, r is the distance between the dynamic permanent magnet set and the static permanent magnet set, h is the distance between the grinding roller and the grinding disc, k is the magnetic repulsion constant, M j is the effective magnetic moment of the static permanent magnet set, M dp is the effective magnetic moment of the moving permanent magnet kit; Among them, the constraint condition is: 0.6×F min ≤ f(M j , M dp , r+h) ≤ 1.1×F max , design the M of the moving permanent magnet kit dp The effective magnetic moment range and the width size of a single moving magnet.

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