A coal mill

Abstract

The present invention discloses a coal mill, belonging to the field of coal mills. The coal mill includes a main shaft, a grinding disc and a shell, a grinding disc sealing structure between the grinding disc and the shell, and a sealing base and a sealing ring between the main shaft and the shell; the sealing base is installed at the bottom of the shell, with a center hole in the middle for the rotating shaft to pass through, and a ring-shaped sealing cavity opening toward the center hole therein; the sealing ring is an annular structure with a mounting hole in the middle, which is sleeved on the main shaft through the mounting hole, and the outer side wall of the annular main body extends outwardly in the circumferential direction to form a main lip and at least one auxiliary lip matched with the main lip; the main lip extends into the sealing cavity to contact and seal with the inner wall of the sealing cavity, and the auxiliary lip extends into the sealing cavity to contact and seal with the inner wall of the sealing cavity or is located outside the sealing cavity to contact and seal with the outer wall of the sealing cavity. The present invention overturns the sealing structure in the prior art in which the seal and the main shaft move relative to each other, and effectively improves the sealing between the main shaft and the shell.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mills, and relates to the sealing technology of coal mills, and more specifically to the sealing structure of a grinding disc and a main shaft in a coal mill. Background Art

[0002] Coal mill is the key equipment for breaking coal and other block materials into powdery materials. It is widely used in cement, silicate products, new building materials, refractory materials, fertilizers, black and non-ferrous metal beneficiation, glass and ceramics and other production industries for dry or wet grinding of various ores and other grindable materials.

[0003] From the working principle point of view, coal mills can be divided into ball mills and roller mills. The structure of roller mills is as follows: Figure 1 As shown, the working principle is as follows: the driving device 3 drives the grinding disc 1 to rotate by driving the main shaft 2, and the grinding roller 4 is installed on the loading frame above the grinding disc 1. The hydraulic loading device 5 provides the grinding pressure of the grinding roller 4 when working by applying a pressing force to the loading frame; when the coal mill is working, the material falls from the coal drop pipe 6 above the grinding disc 1 to the center of the grinding disc 1, and the driving device 3 drives the grinding disc 1 to rotate, and at the same time, hot air enters the coal mill from the air inlet; as the grinding disc 1 rotates, the material moves to the edge of the grinding disc 1 under the action of centrifugal force, and is crushed by the grinding roller 4 when passing through the annular groove on the grinding disc 1; the crushed material is carried up by the high-speed airflow of the wind ring formed by the hot air at the edge of the grinding disc 1, and moves upward with the airflow into the separator at the top of the coal mill; when passing through the upper separator, under the action of the rotating rotor of the separator, the coarse powder will fall on the grinding disc 1 and be re-ground, and the qualified fine powder will be discharged from the mill together with the airflow and collected by the dust collecting device, which is the product.

[0004] When the coal mill is working, in order to allow the coal powder to be smoothly sent out of the coal mill with the air flow, the hot air will form a large wind pressure inside the coal mill, which will dry the sent coal powder on the one hand, and send the coal powder out from the coal powder outlet on the top of the coal mill on the other hand. However, this will cause the coal powder to drill into any gap under the action of the internal wind pressure, and the main shaft is in a rotating state when working, and it cannot be an integrated structure with the stationary coal mill shell, that is, there must be a gap between the coal mill shell and the main shaft. Therefore, the coal powder will drill out from the gap between the main shaft and the coal mill shell under the grinding disc under the wind pressure, causing a large amount of coal powder to leak and pollute the environment. To this end, existing coal mills generally have a sealed air chamber around the main shaft below the grinding disc, and seals are installed between the shell of the sealed air chamber and the bottom of the grinding disc, and between the shell of the sealed air chamber and the main shaft. When the coal mill is working, sealed air is blown into the sealed air chamber to compensate for the wind pressure of the hot air in the coal mill, thereby preventing coal powder from leaking under the action of the hot air.

[0005] For example, the patent document with Chinese patent application number: CN201920609491.8 and publication date: January 17, 2020 discloses a coal mill base sealing assembly and a coal mill, which belongs to the field of coal mill sealing structure. The assembly includes an inner sealing shell and an outer sealing shell connected to each other in an L-shaped structure, an inner sealing wind chamber is formed between the inner sealing shell and the lower part of the grinding disc, and an outer sealing wind chamber is formed between the outer sealing shell and the main shaft, and the outer sealing wind chamber and the inner sealing wind chamber are interconnected structures. The assembly is provided with a sealing structure at the upper and lower ends of the outer sealing wind chamber, and sealing wind is introduced into the outer sealing wind chamber between the two sealing structures. The assembly prevents coal powder from leaking from the gap between the outer sealing shell and the main shaft through a double sealing structure, and blows the coal powder that enters the bottom of the grinding disc with the hot air into the coal mill by introducing sealing wind, thereby further preventing coal powder from leaking.

[0006] However, this solution will have some problems in actual work. First, the main shaft and the two dynamic sealing structures are in relative rotational motion. Long-term working conditions will cause the contact surface between the dynamic sealing structure and the main shaft to be worn, affecting the sealing performance of the main shaft. Secondly, although the sealing air introduced into the external sealing air chamber can blow the coal powder into the coal mill to prevent coal powder leakage, it will also enlarge the gap between the dynamic sealing structure and the main shaft, increasing the risk of coal powder leakage.

[0007] At the same time, the sealing wind will enlarge the gap between the dynamic sealing structure at the lower end and the main shaft, which will cause a large amount of sealing wind to leak from there, resulting in wind pressure loss, making it difficult to control the output frequency of the sealing wind, and failing to ensure a good balance of wind pressure between the outer sealing wind chamber and the inside of the coal mill, affecting the sealing stability. When the sealing wind is stopped or the amount of air blown into the sealing wind is small, the pressure in the outer sealing wind chamber will be lower than the internal pressure of the coal mill, resulting in a back suction phenomenon, causing the hot wind to drive the coal powder into the outer sealing wind chamber and the gap between the main shaft and the dynamic sealing structure. On the one hand, it aggravates the wear between the dynamic sealing structure and the main shaft, and on the other hand, it will also cause the loss of hot air, reducing the efficiency of the hot air in the coal mill to discharge the coal powder from the upper part of the coal mill.

[0008] In particular, due to the characteristics of the main shaft during rotation, it will inevitably have a small radial swing when rotating, which makes the contact precision between the sealing lip of the dynamic seal structure and the main shaft inconsistent, and even different gaps appear, causing uneven wear of the dynamic seal structure, loss of wind pressure and leakage of coal powder, and internal hot air loss. Therefore, the sealing stability of the dynamic seal structure at the main shaft of this solution is relatively poor, it is relatively easy to leak, the sealing life is relatively short, and maintenance is more frequent.

[0009] Another example is the Chinese patent application number: CN201822124796.8, the patent document with the publication date of November 12, 2019, which discloses a sealing device for the lower frame of a coal mill, including an inner sealing mechanism installed in the slag discharge chamber and an outer sealing mechanism installed at the lower end of the main shaft. The inner sealing mechanism is composed of a first elastic seal, a metal soft seal, a pressure-resistant bracket, and a fixed ring, which seals the space between the bottom of the slag discharge chamber and the lower part of the grinding disc to prevent coal powder from leaking out. The outer sealing mechanism includes a second elastic seal, a sealing pressure ring and a metal anti-wear layer, which is provided with a sealing cavity in the circumference of the lower part of the main shaft, and the second elastic seal is arranged in the cavity and close to the main shaft to seal the main shaft.

[0010] Compared with the above scheme, although the structure of this scheme is different, it also has some of the problems mentioned above. That is, the main shaft and the second elastic seal perform relative rotational motion, which is a dynamic sealing structure. Long-term working conditions will cause the contact surface between the second elastic seal and the main shaft to wear, affecting the sealing performance of the main shaft. Similarly, when the main shaft swings radially, it will cause uneven wear of the second seal, loss of wind pressure and leakage of coal powder, and internal hot air will also be lost; at the same time, coal powder will also enter between the contact surface between the second elastic seal and the main shaft, further aggravating the wear rate of the second elastic seal and reducing the sealing performance. Summary of the invention

[0011] 1. Problems to be solved

[0012] The present invention provides a coal mill, the purpose of which is to solve the problem that the sealing between the main shaft and the shell of the coal mill is relatively poor, leakage is more likely to occur, the sealing life is relatively short, and maintenance is more frequent. The coal mill changes the sealing form between the main shaft and the shell, subverts the sealing structure of the relative movement between the seal and the main shaft in the prior art, effectively improves the sealing between the main shaft and the shell, improves the sealing performance, prolongs the life of the seal, and reduces the maintenance frequency.

[0013] 2. Technical solution

[0014] To solve the above problems, the present invention adopts the following technical solutions.

[0015] A coal mill comprises a main shaft, a grinding disc and a housing, a grinding disc sealing structure is provided between the grinding disc and the housing, and a main shaft sealing structure is provided between the main shaft and the housing; the main shaft sealing structure comprises a sealing base and a sealing ring, and the main body of the sealing ring is an annular structure with a mounting hole in the middle;

[0016] The sealing ring is sleeved on the main shaft through the mounting hole and rotates synchronously with the main shaft. The outer wall of the annular main body extends outwardly from the circumference to form a sealing lip, which includes a main lip and at least one auxiliary lip matched with the main lip.

[0017] The sealing base is installed at the bottom of the housing, and is an annular structure as a whole, with a central hole in the middle for the shaft to pass through; the sealing base has an annular sealing cavity, and the sealing cavity is an open structure toward the central hole;

[0018] The main lip of the sealing ring extends into the sealing cavity and contacts and seals with the inner wall of the sealing cavity; the auxiliary lip of the sealing ring extends into the sealing cavity and contacts and seals with the inner wall of the sealing cavity, or the auxiliary lip of the sealing ring is located outside the sealing cavity and contacts and seals with the outer wall of the sealing cavity.

[0019] As a further improvement of the technical solution, the auxiliary lip has one; the root of the auxiliary lip is close to the root of the main lip, and the main lip and the auxiliary lip gradually move away from each other as they extend outward; or the root of the auxiliary lip is far from the root of the main lip, and the main lip and the auxiliary lip gradually move closer to each other as they extend outward.

[0020] As a further improvement of the technical solution, the auxiliary lips are two, namely the first auxiliary lip and the second auxiliary lip, which are respectively located on both sides of the main lip; the root of the first auxiliary lip is close to the root of the main lip, and the main lip and the first auxiliary lip gradually move away from each other as they extend outward, and the first auxiliary lip contacts and seals with the inner wall of the sealing cavity; the root of the second auxiliary lip is far away from the root of the main lip, and the main lip and the second auxiliary lip gradually move closer to each other as they extend outward, and the second auxiliary lip contacts and seals with the outer wall of the sealing cavity.

[0021] As a further improvement of the technical solution, it also includes a pre-tightening member, which is an annular elastic member; when the root of the auxiliary lip approaches the root of the main lip, the main lip and the auxiliary lip gradually move away from each other as they extend outward, and the pre-tightening member is sleeved on the outer wall of the sealing ring between the main lip and the auxiliary lip;

[0022] Alternatively, when the root of the auxiliary lip is away from the root of the main lip and the main lip and the auxiliary lip extend outward and gradually approach each other, the preload component is sleeved on the outer wall of the sealing ring close to the auxiliary lip relative to the main lip and / or on the auxiliary lip.

[0023] As a further improvement of the technical solution, when the root of the auxiliary lip is away from the root of the main lip, the main lip and the auxiliary lip gradually approach each other as they extend outward, and a limiting convex ring is protruded on the side of the outer wall of the sealing ring opposite to the auxiliary lip to limit the axial movement of the preload member.

[0024] As a further improvement of the technical solution, a preload is mounted on the outer wall of the sealing ring between the main lip and the first auxiliary lip; the preload is mounted on the outer wall of the sealing ring close to the second auxiliary lip relative to the main lip, and / or on the second auxiliary lip.

[0025] As a further improvement of the technical solution, a limiting convex ring for limiting the axial movement of the preload member is protruded from the side of the outer wall of the sealing ring opposite to the second auxiliary lip.

[0026] As a further improvement of the technical solution, the preload member is a clamp or a spring.

[0027] As a further improvement of the technical solution, the sealing base includes a substrate, an annular wall and a sealing ring disk; the substrate is a flange disk, which is installed on the shell by bolts, or the substrate is welded to the shell, or the substrate and the shell are an integral structure; the sealing ring disk and the substrate are spaced apart and connected through the two ends of the annular wall, so that a sealed cavity space is enclosed between the substrate, the annular wall and the sealing ring disk.

[0028] As a further improvement of the technical solution, the sealing base is provided with an oil filling port for injecting lubricating medium into the sealing cavity.

[0029] 3. Beneficial effects

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) A coal mill of the present invention changes the sealing form between the main shaft and the housing, overturning the dynamic sealing structure in the prior art in which the seal and the main shaft move relative to each other, and adopts a form in which the seal and the main shaft move synchronously, without relative movement between the two, so that dust is difficult to enter between the seal ring and the main shaft, and coal powder leakage will not occur here; and the structural form of the sealing lip is designed, adopting a main and auxiliary lip matching structure, especially the main lip matches with two auxiliary lips respectively to form two sets of sealing structures. Among them, the main lip and the first auxiliary lip extend into the sealing cavity to form a relatively closed space, and the second auxiliary lip presses the outer surface of the sealing ring disk from the outside to form a structure that bites the sealing ring disk with the main lip; at this time, the sealing ring and the main shaft move synchronously as a whole. Compared with the traditional rotating dynamic seal between the main shaft and the casing, even if the main shaft swings radially, there will generally be no gap between the sealing ring and the main shaft, and the friction between the two will not cause the sealing ring to be damaged; at the same time, the main lip, the first auxiliary lip and the second auxiliary lip jointly form a triple sealing structure inside and outside the sealing cavity. If the hot air drives the coal powder into the main shaft sealing structure, it needs to pass through the triple seals in sequence before it leaks, which effectively improves the sealing between the main shaft and the casing. In particular, the sealing air enters the sealing cavity through the first auxiliary lip, which will cause the main lip and the first auxiliary lip of the sealing ring to open outward, further pressing the inner wall of the sealing cavity, and the sealing air will hardly leak out, and the sealing air pressure will hardly be lost. Even if the main lip and the first auxiliary lip are worn, the sealing performance can be well guaranteed. At the same time, the second auxiliary lip can also prevent the outside air from being sucked back into the sealing cavity when the sealing air is stopped, which can effectively prevent the outside dust from flowing into the sealing lip of the sealing ring and the sealing cavity, thereby aggravating the wear of the sealing lip and extending the service life of the sealing ring.

[0032] (2) A coal mill of the present invention has a pre-tightening member in the form of an annular elastic member mounted on the outer wall of the sealing ring, which can apply radial pre-tightening force to the installed sealing ring to ensure the tightness of the sealing ring and the main shaft, so that the two always rotate synchronously and reduce the possibility of dust entering the interface between the two. In particular, when the pre-tightening member is mounted between the main lip and the first auxiliary lip, the pre-tightening member can also squeeze the main lip and the first auxiliary lip to both sides, so that the V-shaped structure formed by them opens outward, and the contact tightness between the main lip and the first auxiliary lip and the inner wall of the sealing cavity is further strengthened, further improving the sealing performance, and having the function of compensating the wear of the sealing lip. When the pre-tightening member is mounted on the outer wall of the sealing ring close to the second auxiliary lip opposite to the main lip, it can squeeze the second auxiliary lip, so that the contact tightness between the second auxiliary lip and the outer wall of the sealing ring disk is further strengthened, further improving the sealing performance, and having the function of compensating the wear of the sealing lip.

[0033] (3) In a coal mill of the present invention, the sealing lip is arranged on the outer wall of the sealing ring. Compared with the conventional dynamic seal in which the sealing lip is arranged on the surface in contact with the main shaft, the sealing lip can be extended to a longer height, so that even if the sealing lip is greatly worn against the wall of the sealing chamber during operation, the sealing lip can still be kept in close contact with the wall of the sealing chamber with the sealing air, thereby ensuring the sealing performance of the main shaft;

[0034] (4) A coal mill of the present invention has an oil filling port connected to the sealing cavity on the sealing base. Lubricating medium such as grease, graphite or butter can be injected into the sealing cavity through the oil filling port, so that an oil film can be formed on the inner wall of the sealing cavity where the sealing lip contacts, thereby reducing friction resistance, reducing the wear of the sealing lip, and extending the service life of the sealing cavity. At the same time, the lubricating medium filled in the sealing cavity can also further improve the sealing performance of the sealing cavity.

[0035] (5) A coal mill of the present invention has a sealed air chamber baffle disposed around the main shaft, and an elastic seal is installed on the sealed air chamber baffle to partition the sealed air chamber into an annular space formed between the enclosing guard plate and the sealed air chamber baffle and a narrow and long slit space formed between the sealed air chamber baffle and the main shaft sealing structure, thereby further improving the sealing effect, further improving the sealed air pressure maintaining effect, and further reducing the possibility of hot air back suction; and the metal soft seal can adapt to the high-temperature sealing environment caused by the hot air and is not easily damaged.

[0036] (6) A coal mill of the present invention is provided with a scraper at the outer side of the lower part of the grinding disc. The scraper can rotate synchronously with the grinding disc to scrape away the gangue and gravel that cannot be blown up by the airflow due to their large mass and overflow from the side of the grinding disc under the action of centrifugal force, and discharge them through the gravel coal discharge port provided on the coal mill, thereby preventing the gangue and gravel, which are relatively hard debris, from staying in the coal mill and causing great wear to the parts of the coal mill. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of a coal mill in the prior art;

[0038] Figure 2 It is a schematic diagram of the sealing structure between the grinding disc and the main shaft in the coal mill of the present invention;

[0039] Figure 3 for Figure 2 A partial enlarged view of the middle A;

[0040] Figure 4 It is a schematic structural diagram of the sealing ring of the present invention.

[0041] In the figure:

[0042] 100, sealing ring; 110, main lip; 120, first auxiliary lip; 130, second auxiliary lip; 140, preload member; 150, limiting convex ring;

[0043] 200, spindle;

[0044] 300, sealing base; 310, sealing chamber; 320, flange; 330, sealing ring; 340, ring wall;

[0045] 400, grinding disc;

[0046] 500, housing; 510, air inlet; 520, enclosure guard plate; 530, metal soft seal; 540, clamping flange; 550, sealing air chamber baffle; 560, elastic seal;

[0047] 600. Scraper. DETAILED DESCRIPTION

[0048] The present invention is further described below in conjunction with specific embodiments and drawings.

[0049] Example

[0050] The existing coal mill structure is as follows Figure 1 As shown, its working principle has been described in detail in the background technology. The coal mill is provided with dynamic sealing structures between the shell and the bottom of the grinding disc, and between the shell and the main shaft, and a sealed wind chamber is formed between the two dynamic sealing structures. Through a detailed analysis of the background technology, we know that when the existing coal mill is working, the seal at the main shaft adopts a more conventional dynamic seal, that is, the sealing lip is in contact with the main shaft through rotation. However, under the harsh working conditions of the coal mill internal wind pressure, large internal dust, and radial swing of the main shaft, it is difficult for the traditional dynamic seal to ensure the stability of the seal, which is prone to leakage, and the sealing life is relatively short, which will lead to more frequent maintenance.

[0051] In order to solve the above problems, this embodiment provides a coal mill, which changes the sealing form between the main shaft and the housing, subverts the dynamic sealing structure of relative movement between the seal and the main shaft in the prior art, and adopts the form of synchronous movement of the seal and the main shaft, without relative movement between the two, in order to improve the sealing between the main shaft and the housing. At the same time, the sealing structure between the grinding disc and the housing is also optimized to improve the overall sealing effect. The specific sealing structure and working principle of the coal mill are described in detail below.

[0052] like Figure 2 As shown, the sealing structure of the grinding disc 400 and the main shaft 200 of the coal mill is given. It can be seen that a grinding disc sealing structure is set between the housing 500 and the bottom of the grinding disc 400, and a main shaft sealing structure is set between the housing 500 and the main shaft 200. A sealed wind chamber is formed between the grinding disc sealing structure and the main shaft sealing structure through the housing 500, the grinding disc 400 and the main shaft 200, and sealed wind can be introduced into the sealed wind chamber through the air inlet 510.

[0053] Combination Figure 2 and Figure 3 As shown, the main shaft sealing structure mainly includes a sealing base 300 and a sealing ring 100. Among them, the sealing base 300 is installed on the outer bottom of the shell 500, and can be installed by bolts or welding, or it can be an integral structure with the shell 500. The sealing base 300 is an annular structure as a whole, with a center hole in the middle for the main shaft 200 to pass through, and the sealing base 300 has an annular sealing cavity 310, and the sealing cavity 310 is an open structure toward the center hole. Specifically in this embodiment, the sealing base 300 includes a flange 320, an annular wall 340 and a sealing ring disk 330, and the flange 320 is fixed to the shell 500 by bolts. The sealing ring disk 330 is spaced apart from the flange 320 and connected at both ends of the annular wall 340. Preferably, the sealing ring disk 340 and the flange 320 are basically parallel and spaced apart. In this way, the flange 320, the annular wall 330 and the sealing ring disk 340 enclose a sealing cavity 310 space, that is, Figure 3 The structure of the sealing base 300 is very important, as it cooperates with the sealing ring 100 to form a sealing surface, and is also a key point required to realize the innovative main shaft sealing structure of the present invention.

[0054] like Figure 4As shown, the sealing ring 100 used for sealing at the main shaft 200 is different from the traditional dynamic sealing structure. It is annular in structure as a whole, and has a mounting hole in the middle for mounting the sealing ring 100 on the main shaft 200. However, unlike the structure of the traditional dynamic seal in which the sealing lip extends toward the center on the inner wall of the mounting hole, the sealing ring 100 in this embodiment extends the sealing lip outward in the circumferential direction of the outer wall of the annular body, and the sealing lip is used to cooperate and seal with the above-mentioned sealing base 300. A transition fit or an interference fit can be adopted between the mounting hole of the sealing ring 100 and the main shaft 200. It is necessary to ensure that when the coal mill is working, the sealing ring 100 rotates with the main shaft 200, and there is no relative rotation between the two. The sealing lip of the sealing ring 100 extends into the sealing cavity of the sealing base 300 and contacts and seals with the surface of the sealing cavity, so that the sealing ring 100 and the sealing base 300 are rotated and sealed, which completely subverts the sealing form of the traditional dynamic seal.

[0055] In order to achieve a better sealing effect, this embodiment optimizes the design of the sealing lip structure of the sealing ring 100. Figure 3 and Figure 4 As shown, the sealing ring 100 has at least one main lip 110, which extends into the sealing cavity 310 of the sealing base 300 and contacts and seals with the surface of the sealing ring disk 330. When the main shaft 200 rotates, the main lip 110 and the surface of the sealing ring disk 330 are in friction contact to form a sealing surface. Of course, the sealing ring 100 can also have an auxiliary lip to cooperate with the main lip 110 to improve the sealing performance. In this embodiment, the sealing ring 100 has not only one main lip 110, but also two auxiliary lips, namely a first auxiliary lip 120 and a second auxiliary lip 130, which are respectively located on both sides of the main lip 110. Among them, the root of the first auxiliary lip 120 is close to the root of the main lip 110, and the main lip 110 and the first auxiliary lip 120 gradually move away from each other when extending outward, forming a V-shaped structure. During installation, the main lip 110 and the first auxiliary lip 120 are both extended into the sealing cavity 310 of the sealing base 300, the main lip 110 contacts and seals with the surface of the sealing ring disk 330, and the first auxiliary lip 120 contacts and seals with the surface of the flange 320, thereby completely closing the opening of the sealing cavity 310. The root of the second auxiliary lip 130 is away from the root of the main lip 110, and the second auxiliary lip 130 and the main lip 110 gradually approach each other as they extend outward, forming an eight-shaped structure. During installation, the second auxiliary lip 130 is located outside the sealing base 300, and contacts and seals with the outer surface of the sealing ring disk 330 of the sealing base 300, that is, the sealing ring disk 330 of the sealing base 300 is inserted between the second auxiliary lip 130 and the main lip 110, and is tightly bitten.

[0056] It can be seen from the above spindle seal structure design that the seal ring 100 is fixedly connected to the spindle 200, and the two move synchronously as a whole. Compared with the traditional rotary dynamic seal between the spindle and the housing, even if the spindle 200 swings radially, there is generally no gap between the seal ring 100 and the spindle 200, not to mention the phenomenon that the seal ring 100 is damaged due to friction between the two. In this case, coal powder basically does not enter between the seal ring 100 and the spindle 200, and there is basically no leakage between the two. In order to better adapt to the radial swing of the spindle 200, the diameter of the sealing cavity 310 of the sealing base 300 can be set to be slightly larger than the outer diameter of the sealing lip of the seal ring 100, which can ensure that there is enough radial swing space.

[0057] Then the sealing structure of the sealing ring 100 and the sealing cavity 310 of the sealing base 300 is crucial. In this embodiment, the main lip 110, the first auxiliary lip 120 and the second auxiliary lip 130 together form a triple sealing structure inside and outside the sealing cavity 310. It can be seen that the main lip 110 and the first auxiliary lip 120 are a group that cooperates with each other, and the main lip 110 and the second auxiliary lip 130 are another group that cooperates with each other. If hot air drives coal powder into the sealed air chamber and reaches the main shaft sealing structure, it needs to pass through the triple seals in sequence before leakage occurs, which can effectively improve the sealing between the main shaft 200 and the housing 500. More importantly, due to the V-shaped structure of the main lip 110 and the first auxiliary lip 120, the sealing air enters the sealing cavity 310 through the first auxiliary lip 120, which will open the main lip 110 and the first auxiliary lip 120 of the sealing ring 100 outward, further pressing the inner wall of the sealing cavity 310, just like the vacuum tire structure of a car, the sealing air will hardly leak out, and the sealing air pressure will hardly be lost, so there is no need to compensate the pressure of the sealing air, and the sealing air pressure is also relatively small, which can be kept consistent with or slightly larger than the hot air pressure. Moreover, even if the main lip 110 and the first auxiliary lip 120 are worn, the sealing performance can be well guaranteed. At the same time, the second auxiliary lip 130 can also prevent the outside air from being sucked back into the sealing cavity 310 when the sealing air is stopped, and can effectively prevent the outside dust from flowing into the sealing lip of the sealing ring 100 and the sealing cavity 310, thereby aggravating the wear of the sealing lip and extending the service life. Of course, in order to further improve the sealing effect and reduce friction, a serrated structure can be set at the contact point between the sealing lip and the sealing surface of the sealing ring 100.

[0058] The sealing wind inlet 510 can also be optionally set on the sealing base 300. When the sealing wind enters the sealing cavity 310 of the sealing base 300, the V-shaped structure formed by the main lip 110 and the first auxiliary lip 120 can be directly opened outward, which has a better compression effect on the V-shaped structure and further improves the sealing performance of the lower sealing structure.

[0059] In addition, the traditional dynamic seal generally sets the sealing lip on the surface where the sealing ring and the main shaft 200 are in contact, and the size of the sealing lip will be greatly limited, that is, the height of the sealing lip is relatively short. In this embodiment, the sealing lip is set on the outer wall of the sealing ring 100. Compared with the traditional dynamic seal structure, the sealing lip can be extended to a longer height, so that even if the sealing lip is greatly worn with the wall of the sealing cavity 310 during operation, the sealing air can also make the sealing lip still keep a close fit with the wall of the sealing cavity 310, thereby ensuring the sealing of the main shaft 200. Moreover, because there is no relative movement between the sealing ring 100 and the main shaft 200, the main shaft 200 is no longer limited to a rotating shaft, but can be a square shaft or a rectangular shaft, and the shape of the mounting hole of the corresponding sealing ring 100 matches the main shaft 200, so that the scope of application is wider.

[0060] Taking into account the installation reliability and sealing effect of the sealing ring 100, this embodiment further optimizes the design based on the above-mentioned sealing ring 100, and adds a pre-tightening member 140 structure design, which is a ring-shaped elastic member, which is sleeved on the outer wall of the sealing ring 100 and can apply radial pre-tightening force to the installed sealing ring 100 to ensure the tightness of the sealing ring 100 and the main shaft 200. The two always rotate synchronously, and the possibility of dust entering the interface between the two is further reduced. One or more pre-tightening members 140 can be installed. In this embodiment, it is preferred to install two pre-tightening members 140. Figure 3 and Figure 4 As shown, one of the pre-tightening members 140 is sleeved between the main lip 110 and the first auxiliary lip 120. In addition to the above radial pre-tightening effect, a more prominent effect is that it can squeeze the main lip 110 and the first auxiliary lip 120 to both sides, that is, to make the V-shaped structure formed by them open outward, and the contact tightness between the main lip 110 and the first auxiliary lip 120 and the inner wall of the sealing cavity is further strengthened, further improving the sealing performance, and having the function of compensating the wear of the sealing lip. Another pre-tightening member 140 is arranged on the side of the second auxiliary lip 130 relative to the main lip 110, and is sleeved on the outer wall of the sealing ring 100. At the same time, a limiting protruding ring 150 is protruded on the outer wall of the sealing ring 100 on the other side of the pre-tightening member 140 to limit the axial movement of the pre-tightening member 140. In addition to the aforementioned radial pre-tightening function, the other pre-tightening member 140 has a more prominent function of squeezing the second auxiliary lip 130, so that the contact tightness between the second auxiliary lip 130 and the outer wall of the sealing ring disk 330 is further strengthened, further improving the sealing performance, and also has the function of compensating the wear of the sealing lip. In addition, the two pre-tightening members 140 are arranged at both ends of the axial direction of the sealing ring 100, and the radial pre-tightening force of the sealing ring 100 is more reliable. For the specific selection of the pre-tightening member 140, existing pre-tightening components such as a clamp or a spring can be used. In this embodiment, a clamp is selected.

[0061] Furthermore, a pre-tightening member 140 may be mounted on the second auxiliary lip 130 to directly apply radial pre-tightening force to the second auxiliary lip 130, so that the second auxiliary lip 130 is more closely attached to the outer wall of the sealing cavity 310 of the sealing base 300. For the installation of the second auxiliary lip 130, it may be considered to open an annular groove on the second auxiliary lip 130.

[0062] In order to reduce the wear of the sealing ring 100 during operation, the present embodiment has an oil filling port (not shown in the figure) on the sealing base 300 for injecting lubricating medium into the sealing cavity 310. Specifically, it is preferably arranged on the annular wall 340. The oil filling port is in a closed state when the lubricating medium is not injected. Lubricating medium such as grease, graphite or butter can be injected into the sealing cavity 310 through the oil filling port, and an oil film can be formed on the inner wall of the sealing cavity 310 where the sealing lip contacts, thereby reducing friction resistance, reducing the wear of the sealing lip, and extending the service life of the sealing ring 100; at the same time, the lubricating medium filled in the sealing cavity 310 can also further improve the sealing performance of the sealing cavity 310.

[0063] It should be noted that, although the above spindle seal structure is used in a coal mill in this embodiment, it is not limited to the coal mill. As long as it is used in the occasion of a rotating shaft dynamic seal, it can be selectively used in consideration of the above-mentioned harsh working conditions, except that the installation position of the seal base 300 is different and the seal ring 100 is matched with different rotating shafts. Therefore, this embodiment proposes an innovative structure of a rotating shaft dynamic seal, which has a wide range of applications.

[0064] The grinding disc sealing structure is a sealing structure between the housing 500 and the bottom of the grinding disc 400, and can adopt an existing structural form. This embodiment makes some changes based on the existing structure. Figure 2 As shown, in the housing 500, a sealed air chamber baffle 550 is arranged around the outside of the main shaft 200. The top shape of the sealed air chamber baffle 550 corresponds to the bottom shape of the grinding disc 400, and a rotating space for the grinding disc 400 is reserved, thereby forming a narrow gap to reduce the sealing wind from entering the main shaft sealing structure. In the housing 500, an annular enclosure guard plate 520 is arranged outside the sealed air chamber baffle 550. The lower end of the enclosure guard plate 520 is mounted to the bottom of the housing 500 through a flange, and a metal soft seal 530 is installed on the upper end. The metal soft seal 530 contacts and seals with the bottom of the grinding disc 400, thereby forming a sealed air chamber between the enclosure guard plate 520 and the main shaft sealing structure. Because the enclosure guard plate 520 is located near the hot air inlet of the coal mill, the temperature is relatively high, which can reach 300℃~400℃. Conventional seals are easily damaged and lose their function in such a high temperature environment, which increases the risk of coal powder leakage. Therefore, a metal soft seal 530 is used for sealing, which is adapted to the high temperature sealing environment and is not easily damaged. In addition, the metal soft seal 530 can be fixedly installed on the enclosure guard plate 520 through the annular clamping flange 540, which is also convenient for disassembly, assembly and replacement.

[0065] In this embodiment, an elastic seal 560 is further installed on the sealed wind chamber baffle 550, which is also in contact and sealed with the bottom of the grinding disc 200, thereby dividing the sealed wind chamber into two parts, namely, the annular space formed between the enclosing guard plate 520 and the sealed wind chamber baffle 550, and the narrow and long slit space formed between the sealed wind chamber baffle 550 and the main shaft sealing structure, which can further improve the sealing effect, further improve the sealed wind pressure maintaining effect, and further reduce the possibility of hot air back suction.

[0066] In addition, in this embodiment, a scraper 600 is installed at the outer side of the lower part of the grinding disc 400. The scraper 600 can rotate synchronously with the grinding disc 400 to scrape away the coal gangue and stones that cannot be blown up by the airflow due to their large mass and overflow from the side of the grinding disc 400 under the action of centrifugal force, and discharge them through the gravel coal discharge port provided on the coal mill, thereby preventing harder debris such as coal gangue and stones from staying in the coal mill and causing greater wear on the components of the coal mill.

[0067] In summary, a coal mill in this embodiment changes the traditional sealing form between the main shaft and the housing, and the seal moves synchronously with the main shaft as a whole, thereby improving the sealing between the main shaft and the housing, improving the sealing performance, and increasing the service life of the seal.

[0068] The present invention and its embodiments are described schematically above, and the description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by it and designs a structural method and an embodiment similar to the technical solution without creativity without departing from the purpose of the invention, they shall all fall within the protection scope of the present invention.

Claims

1. A coal mill, comprising a main shaft (200), a grinding disc (400) and a housing (500), a grinding disc sealing structure being provided between the grinding disc (400) and the housing (500), and a main shaft sealing structure being provided between the main shaft (200) and the housing (500); the main shaft sealing structure comprising a sealing base (300) and a sealing ring (100), the main body of the sealing ring (100) being an annular structure with a mounting hole in the middle; the characteristics are as follows: The sealing ring (100) is sleeved on the main shaft (200) through the mounting hole and rotates synchronously with the main shaft (200), and a sealing lip is extended outwardly from the outer wall of the annular main body in the circumferential direction, and the sealing lip includes a main lip (110) and at least one auxiliary lip matched with the main lip (110); The sealing base (300) is installed at the bottom of the housing (500), and is an annular structure as a whole, with a central hole in the middle for the rotating shaft to pass through; the sealing base (300) has an annular sealing cavity (310), and the sealing cavity (310) is an open structure towards the central hole; The main lip (110) of the sealing ring (100) extends into the sealing cavity (310) and contacts and seals with the inner wall of the sealing cavity (310); the auxiliary lip of the sealing ring (100) extends into the sealing cavity (310) and contacts and seals with the inner wall of the sealing cavity (310); or the auxiliary lip of the sealing ring (100) is located outside the sealing cavity (310) and contacts and seals with the outer wall of the sealing cavity (310); The sealing base (300) comprises a base plate, an annular wall (340) and a sealing ring disk (330); the base plate is a flange disk (320) mounted on the housing (500) by means of bolts, or the base plate is welded to the housing (500), or the base plate and the housing (500) are an integral structure; the sealing ring disk (330) and the base plate are spaced apart and connected via two ends of the annular wall (340), so that a sealing cavity (310) is enclosed between the base plate, the annular wall (340) and the sealing ring disk (330).

2. The coal mill according to claim 1, characterized in that: The auxiliary lip has one; the root of the auxiliary lip is close to the root of the main lip (110), and the main lip (110) and the auxiliary lip gradually move away from each other when extending outward; or the root of the auxiliary lip is far from the root of the main lip (110), and the main lip (110) and the auxiliary lip gradually move toward each other when extending outward.

3. The coal mill according to claim 1, characterized in that: The auxiliary lips include two, namely a first auxiliary lip (120) and a second auxiliary lip (130), which are respectively located on both sides of the main lip (110); the root of the first auxiliary lip (120) is close to the root of the main lip (110), the main lip (110) and the first auxiliary lip (120) gradually move away from each other when extending outward, and the first auxiliary lip (120) contacts and seals with the inner wall of the sealing cavity (310); the root of the second auxiliary lip (130) is far from the root of the main lip (110), the main lip (110) and the second auxiliary lip (130) gradually move closer to each other when extending outward, and the second auxiliary lip (130) contacts and seals with the outer wall of the sealing cavity (310).

4. The coal mill according to claim 2, characterized in that: It also includes a pre-tightening member (140), which is an annular elastic member; when the root of the auxiliary lip approaches the root of the main lip (110), and the main lip (110) and the auxiliary lip gradually move away from each other as they extend outward, the pre-tightening member (140) is sleeved on the outer wall of the sealing ring (100) between the main lip (110) and the auxiliary lip; Alternatively, when the root of the auxiliary lip is away from the root of the main lip (110), and the main lip (110) and the auxiliary lip extend outward and gradually approach each other, the preload member (140) is sleeved on the outer wall of the sealing ring (100) close to the auxiliary lip on the side of the main lip (110), and / or on the auxiliary lip.

5. The coal mill according to claim 4, characterized in that: When the root of the auxiliary lip is away from the root of the main lip (110), and the main lip (110) and the auxiliary lip gradually approach each other as they extend outward, a limiting convex ring (150) for limiting the axial movement of the pre-tightening member (140) is protruded on the side of the outer wall of the sealing ring (100) opposite to the auxiliary lip.

6. The coal mill according to claim 3, characterized in that: A pre-tightening component (140) is sleeved on the outer wall of the sealing ring (100) between the main lip (110) and the first auxiliary lip (120); the pre-tightening component (140) is sleeved on the outer wall of the sealing ring (100) close to the second auxiliary lip (130) on the side opposite to the main lip (110) and / or on the second auxiliary lip (130).

7. The coal mill according to claim 6, characterized in that: A limiting convex ring (150) for limiting axial movement of the pre-tightening member (140) is protruded on a side of the outer wall of the sealing ring (100) opposite to the second auxiliary lip (130).

8. The coal mill according to any one of claims 4 to 7, characterized in that: The pre-tightening member (140) is a clamp or a spring.

9. The coal mill according to any one of claims 1 to 7, characterized in that: The sealing base (300) is provided with an oil injection port for injecting lubricating medium into the sealing cavity (310).

Images