Horizontal dryer shaft body coaxial sealing structure and sealing method

Abstract

The invention discloses a coaxial sealing structure for a shaft body of a horizontal drying machine, and relates to the technical field of powder drying equipment. The structure comprises a shaft body and a box body, a double-spiral material pushing shaft sleeve is welded on the shaft body, and a combined sealing box is fixed on the box body. The double-helix material pushing shaft sleeve is in clearance fit with the inner side wall of the combined sealing box, two annular grooves with air holes are formed in the combined sealing box, and the air hole in the right side is connected with a high-pressure air source so that a two-way sealing air curtain can be formed in the clearance. A spiral blade is arranged at the right end of the double-spiral material pushing shaft sleeve, and a spiral structure groove is formed in the outer circular surface of the spiral blade. The high-pressure air curtain is used for preventing powder from invading and blowing out abrasion residues, meanwhile, the rotating spiral blades and the spiral grooves are used for pushing the powder back to the box body, pollution is thoroughly eradicated, the service life of a sealing system is remarkably prolonged, and the device is particularly suitable for the fields of medicine, food, electronic-grade powder and the like with ultra-clean requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of powder drying equipment, in particular to a horizontal dryer shaft body coaxial sealing structure and sealing method. BACKGROUND

[0002] The horizontal dryer is a key equipment widely used in the chemical, food, pharmaceutical, electronic and other industries for drying powder and particle materials. Its core structure includes a fixed box (vessel) and a shaft body with a spiral ribbon agitator inside. The shaft body usually penetrates the box side wall from the drive end (usually the left side) into the interior, so there is an annular gap between the shaft body and the box. In order to prevent the powder from escaping from this gap during drying and to ensure the working pressure or vacuum degree inside the equipment, it is crucial to set a reliable shaft seal here.

[0003] Currently, the most common sealing method in this field is contact sealing, such as packing seal or mechanical seal (lip seal ring, O-ring, etc.). The basic principle is to install a sealing element between the shaft body and the box, relying on the interference fit and elastic contact between the sealing element and the surface of the shaft body to achieve sealing effect. In view of the defects of this technology, the industry has made many improvement attempts, but none of them has fundamentally solved the problem.

[0004] For example, in the patent application with publication (announcement) number CN202310223172.2, named "Mechanical seal special for horizontal dryer", a cooling cavity is set in the sealing box and cooling water is introduced to reduce the temperature of the sealing area, aiming to solve the problem of axial displacement and performance decline of mechanical seal due to thermal expansion. This scheme delays the aging of the sealing element to some extent, but it does not change the nature of the contact and friction between the sealing element and the shaft body, so it cannot avoid the core defect of material pollution by wear particles. It also has no effective countermeasures for the accelerated wear caused by powder intrusion into the sealing surface.

[0005] For another example, in the utility model patent with authorization announcement number CN222416009U, named "Bearing and mechanical seal combination device for horizontal dryer", the overall firmness and stability are improved through the combination design of gland, screw, multiple circular rings and dynamic ring. This scheme focuses on improving the mechanical reliability of the structure, but it still cannot provide a fundamental solution to the problems of sealing element wear, powder intrusion and material pollution caused thereby in dynamic operation.

[0006] In summary, the sealing schemes in the existing technology (including the above cited patents) mostly focus on delaying wear, enhancing cooling or improving structural stability. They all belong to improvements within the "contact sealing" framework, and have the following common defects that cannot be overcome: 1. Cannot prevent pollution: the direct contact friction between the seal and the rotating shaft body will inevitably produce wear particles (such as rubber chips, polytetrafluoroethylene chips, etc.), which will directly invade the equipment cavity and cause fatal pollution to the powder products that require ultra-clean, such as medicines and food.

[0007] 2. Easy to be affected by powder invasion: the powder in the drying process is easy to invade the sealing surface. These small powder particles act as abrasives and can sharply accelerate the wear of the seal, even scratch the surface of the shaft body, damage the sealing integrity, and form a vicious cycle of sealing failure and increased pollution.

[0008] 3. High maintenance cost: due to the above reasons, the seal needs to be replaced frequently, resulting in increased equipment downtime, high maintenance cost, and serious impact on the continuity and economy of production.

[0009] Therefore, there is an urgent need in the art for a new sealing structure that can break out of the traditional contact sealing mindset, not only to block the outward leakage of internal wear particles, but also to effectively prevent the invasion of external powder, and fundamentally solve the problem of two-way pollution path. SUMMARY

[0010] In view of the above, in order to overcome the defects of the prior art, the present application provides a horizontal dryer shaft body coaxial sealing structure and sealing method, which effectively solves the problems of the existing equipment, such as the inability to prevent pollution, the easy invasion of powder, and the high maintenance cost of the sealing structure at the end of the main shaft of the dryer.

[0011] The technical solution solved is that a shaft body and a box body of a dryer are provided, the shaft body is sleeved with a double helical pushing shaft sleeve on the outside, the double helical pushing shaft sleeve rotates with the shaft body, the box body is fixed with a combined sealing box, the double helical pushing shaft sleeve is in the combined sealing box, the shaft body penetrates through the combined sealing box, and the left end is supported on the left end of the combined sealing box through a bearing; the double helical pushing shaft sleeve and the inner side wall of the combined sealing box are in clearance fit, two annular grooves are formed on the inner side wall of the part of the double helical pushing shaft sleeve in the combined sealing box, gas holes are arranged on the two annular grooves, and the gas hole on the right side is in communication with a high-pressure gas source; a helical blade is fixed at the right end of the double helical pushing shaft sleeve, the helical blade is adapted to the inner side wall of the combined sealing box, and a helical structure groove is formed on the part of the outer cylindrical surface of the double helical pushing shaft sleeve between the helical blade and the annular groove.

[0012] Further, the left end of the combined sealing box is provided with a bearing seat, two locating bearings are installed in the bearing seat, a spacing inner ring and a spacing outer ring are installed between the two locating bearings, the outer ring of the two locating bearings can clamp the spacing outer ring, and the inner ring of the two locating bearings can clamp the spacing inner ring; a bearing gland is installed at the left end of the box body; the bearing gland presses the outer ring of the left bearing; a locking nut is arranged at the left side of the bearing gland, the locking nut is sleeved on the shaft and is screwed together through a threaded structure; when the locking nut is screwed, the nut can clamp the two locating bearings and the spacing inner ring therebetween through the top ring to the right, forming an integral whole.

[0013] Further, a cavity is formed in the middle of the combined sealing box, a double helical pushing shaft sleeve is fixedly sleeved on the right part of the shaft body, and the left end of the double helical pushing shaft sleeve terminates at the middle cavity of the combined sealing box; a packing group is sleeved on the double helical pushing shaft sleeve, the packing group is composed of a plurality of sealing rings, the packing group is located in the packing groove at the right part of the cavity of the combined sealing box, and the packing group seals between the shaft body and the box body; an annular packing gland is sleeved on the left end of the double helical pushing shaft sleeve, the right end of the packing gland abuts against the packing group to make the plurality of sealing rings in the packing group closely close to each other; the left end of the packing gland is outwardly folded to form a folded edge, and the folded edge and the right side wall of the cavity are fixed together through a plurality of bolt and nut structures.

[0014] Further, an annular corrugated plate is fixed to the outside of the right end of the combined sealing box, the cross section of the corrugated plate is in a wave shape, and the outer edge of the corrugated plate is fixed to the box body.

[0015] The present application has a clever structure, through the creation of "high pressure gas sealing barrier and double mechanical return" collaborative mechanism, the high pressure gas flowing into the combined sealing box forms a double gas curtain, completely blocks the wear and tear of the pollutants into the box body and the invasion of the powder into the sealing area; at the same time, the double physical barrier composed of helical blade and helical groove actively pushes the powder back to the box body, so as to solve the pollution problem, significantly improve the sealing reliability and equipment life, and realize the super clean production. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a front view of the present application.

[0017] Figure 2 It is a front view of the present application. Figure 1 It is an enlarged view of A in the middle.

[0018] Figure 3 It is an enlarged view of B in the middle. Figure 1 It is an enlarged view of B in the middle.

[0019] Figure 4 It is a front view of the double helical pushing shaft sleeve in the present application.

[0020] Figure 5 It is a three-dimensional structure diagram of the double helical pushing shaft sleeve and the helical structure groove and helical blade thereon in the present application. DETAILED DESCRIPTION

[0021] The specific embodiments of the present application are further described in detail below with reference to the accompanying drawings.

[0022] By Figures 1 to 5 Given, the present application includes the shaft body 12 and the box body 13 of the dryer, the shaft body 12 is externally fitted with a double helical pushing shaft sleeve 10, the double helical pushing shaft sleeve 10 rotates with the shaft body 12, the box body 13 is fixed with a combined sealing box 9 (see Figure 1 ), the double helical pushing shaft sleeve 10 is in the combined sealing box 9, the shaft body 12 penetrates the combined sealing box 9, the left end is supported by the bearing at the left end of the combined sealing box 9; the double helical pushing shaft sleeve 10 is gap-fitted between the inner side wall of the combined sealing box 9, two annular grooves are formed on the inner side wall of the part of the combined sealing box 9 where the double helical pushing shaft sleeve 10 is located (see Figure 1 ), air holes are arranged on the two annular grooves, and the air hole on the right side is communicated with the high-pressure gas source; the right end of the double helical pushing shaft sleeve 10 is fixedly provided with a helical blade (see Figure 1 、 4 , 5), the helical blade is adapted to the inner side wall of the combined sealing box 9, and a helical structure groove is formed on the part of the outer circular surface of the double helical pushing shaft sleeve 10 between the helical blade and the annular groove (see Figure 1 、 4 , 5).

[0023] It is worth noting that the high pressure in the high-pressure gas source described herein is a relative concept, the gas source pressure is higher than the atmospheric pressure and the working gas pressure in the box body 13, and in the drying process, the box body 13 is generally in a state of micro-negative pressure.

[0024] In order to install the shaft body 12 and improve the coaxiality of the shaft body 12 and the combined sealing box 9, the left end of the combined sealing box 9 is provided with a bearing seat, two positioning bearings 4 are installed in the bearing seat, a spacing inner ring 5 and a spacing outer ring 6 are installed between the two positioning bearings 4, the outer ring of the two positioning bearings 4 can clamp the spacing outer ring 6, and the inner ring of the two positioning bearings 4 can clamp the spacing inner ring 5; the bearing gland 1 is installed at the left end of the box body 13; the bearing gland 1 presses the outer ring of the left bearing; the left side of the bearing gland 1 is provided with a locking nut 3, the locking nut 3 is fitted on the shaft body 12 and the two are screwed together through the thread structure; when the locking nut 3 is screwed, the nut can clamp the two positioning bearings 4 and the spacing inner ring 5 therebetween through the top ring 2 to the right, forming a whole.

[0025] In order to install the filler group 8, i.e. the sealing element, similar to the traditional one, a cavity is formed in the middle of the combined sealing box 9, the double helical pushing shaft sleeve 10 is fixedly fitted on the right part of the shaft body 12, and the left end terminates at the middle cavity of the combined sealing box 9 (see Figure 1), the double helix pushing shaft sleeve 10 is sleeved with a packing group 8, the packing group 8 is composed of multiple sealing rings, the packing group 8 is in the packing groove in the right part of the cavity of the combined sealing box 9, and the packing group 8 seals between the shaft body 12 and the box body 13; the double helix pushing shaft sleeve 10 is sleeved with an annular packing gland 7 at the left end, the packing gland 7 abuts against the packing group 8 to make the multiple sealing rings in the packing group 8 close to each other; the left end of the packing gland 7 is outwardly folded to form a folded edge, and the folded edge and the right side wall of the cavity are fixed together through multiple bolt and nut structures.

[0026] In order to install and fix the combined sealing box 9, the combined sealing box 9 is fixed with an annular corrugated plate 11 on the right outer side, the cross section of the corrugated plate 11 is in a wave shape (see Figure 1 、 3 ), and the outer edge of the corrugated plate 11 is fixed on the box body 13.

[0027] In the above, the shaft body 12 is a system driving part, the combined sealing box 9 and the box body 13 are connected and sealed through an annular corrugated plate 11; the inner edge of the corrugated plate 11 is fixed with the outer surface of the combined sealing box 9 through sealing welding, and the outer edge is fixed with the side wall of the box body 13 through sealing welding, so that a reliable static sealing barrier is formed between the two. The corrugated plate 11 structure not only realizes the rigid connection and effective sealing between the combined sealing box 9 and the box body 13, but also can effectively absorb and compensate the vibration, eccentric displacement and installation centering error generated in the rotating process of the shaft body 12 due to its unique flexible deformation characteristics, which not only guarantees the stability of the shaft system operation, but also ensures the long-period sealing reliability of the connection part under dynamic working conditions.

[0028] In the manufacturing process, the double helix pushing shaft sleeve 10 first goes through a rough machining stage, and then is welded with the shaft body 12 into an integral structure, which not only enhances the structural integrity of the part, but also provides a good foundation for subsequent finishing. After welding, the double helix pushing shaft sleeve 10 and the shaft body 12 will enter the finishing process together to ensure that the coaxiality between each machined surface of the double helix pushing shaft sleeve 10 and the shaft body 12 meets the design requirements, and at the same time, the size precision of each key part meets the use needs.

[0029] The combined sealing box 9 as a core functional component needs to strictly control the coaxiality, perpendicularity and dimensional accuracy of each machined surface in the machining process. These geometric accuracies are the key to ensure the coordination and cooperation of the combined sealing box 9 with other components and realize long-term stable operation.

[0030] In the assembly stage, the combined sealing box 9 is precisely assembled with the shaft body 12 through a series of parts such as the bearing gland 1, the top ring 2, the locking nut 3, the positioning bearing 4, and the spacer inner ring 5 and the spacer outer ring 6. The assembly process is through the precise fit of the bearing, aiming to ensure that the shaft body 12 (and the double helix pusher shaft sleeve 10 fixed thereon) and the combined sealing box 9 maintain strict coaxiality and reasonable fit clearance, thereby guaranteeing the precision and reliability of the overall movement. The right end of the combined sealing box 9 is connected with the box body 13 through the corrugated plate 11, which not only fixes the position of the sealing box and prevents it from rotating synchronously with the shaft body 12, but also ensures the sealing performance between the box body 13 and the combined sealing box 9. At the same time, the corrugated plate 11 can effectively compensate for the displacement and coaxial runout that may occur between the shaft body 12 and the box body 13 during equipment operation, eliminating the impact of these deviations on equipment operation without compromising the original fit precision between the combined sealing box 9 and the shaft body 12.

[0031] Subsequently, the filler group 8 is filled into the special filler groove of the combined sealing box 9, and the filler gland 7 is used to uniformly press it to form a reliable seal. Finally, the combined sealing box 9 is installed with the inlet sealing gas source, and the entire assembly process is completed.

[0032] In the initial state of equipment operation, the shaft body 12 is continuously rotated by the driving device. Since the double helix pusher shaft sleeve 10 is welded as a whole after rough machining with the shaft body 12 in the manufacturing process, and then is precisely machined to ensure coaxiality and fit precision, the two form a complete rigid rotating body, realizing synchronous rotation. The combined sealing box 9, which is sleeved outside the double helix pusher shaft sleeve 10, is fixedly connected with the dryer box body 13 through the right end flange, and always remains stationary. At this time, the high-pressure gas source to the gas holes on the upper right annular groove of the combined sealing box 9 has been pre-opened, and clean high-pressure gas is continuously introduced.

[0033] Since the double helix pusher shaft sleeve 10 and the combined sealing box 9 are in precise gap fit, the high-pressure gas rapidly fills the annular gap after entering, and forms a dynamic sealing gas curtain acting on both left and right sides. Under the condition that the flow resistance on both sides is basically balanced, the high-pressure gas will flow to both left and right directions at the same time and in equal amounts, forming a bidirectional sealing barrier.

[0034] The effect of gas flow to the left (resistance to slag): the high-pressure gas flowing to the left effectively sweeps the wear debris (such as rubber particles) generated by the traditional packed seal (consisting of multiple mutually extruded sealing rings) in the left bearing position during operation, and continuously pushes these contaminants to the left, eventually discharging them to the external collection system through the gas holes on the left annular groove, thereby completely eliminating any possibility of wear debris mixing to the right and contaminating the material in the box body 13.

[0035] The rightward airflow (powder blocking): at the same time, the high-pressure gas flowing rightward forms a uniform positive pressure barrier at the gap outlet. This stable air curtain can effectively prevent the powder in the box 13 from invading the gap core area between the combined sealing box 9 and the double helical pushing shaft sleeve 10, and reversely blows the possible invading trace of powder back into the box 13.

[0036] During the stirring process, the powder in the dryer box 13 will try to move to the gap between the shaft 12 and the side wall of the box 13. When the powder approaches the sealing area, it will first encounter the helical blade at the right end of the double helical pushing shaft sleeve 10, which is inside the box 13 and rotates at high speed. The blade acts as the first active defense barrier, using the axial thrust generated during rotation to directly and effectively push most of the powder back into the box 13.

[0037] Even if a small amount of powder manages to pass through the protection of the helical blade, they will enter the gap between the double helical pushing shaft sleeve 10 and the combined sealing box 9. At this time, the helical structure groove located on the left side of the helical blade, which also rotates with the shaft, begins to play the role of the second barrier. These grooves will capture these residual powders and generate a leftward mechanical conveying force during rotation. This leftward mechanical conveying force and the high-pressure airflow flowing rightward form a dynamic balance here, ensuring that these trace amounts of powder are effectively controlled within the sealing area, and ultimately pushed back to the action range of the helical blade under the combined action of mechanical action and airflow, swept back into the box 13 by the blade, thus completing a complete sealing cycle.

[0038] For ease of maintenance, a maintenance opening can be provided near the air hole on the right annular groove. The maintenance opening is in a closed state during daily operation to maintain the sealing integrity. When the equipment needs to be maintained, the maintenance opening can be opened to facilitate the cleaning of possible accumulated debris, residues or powder and other foreign matter, ensuring the long-term reliability of the system.

[0039] The entire system follows the operation principle of "starting the gas first, then starting the machine; stopping the machine first, then stopping the gas", thus ensuring the effectiveness of the sealing during the start-up and stoppage stages. In summary, through the perfect synergy of the bidirectional equal sweeping of high-pressure gas and the mechanical return action of rotating components (double helical pushing shaft sleeve 10, helical blade, helical groove), the invention achieves the absolute blocking of the inward leakage of wear contaminants and the layer-by-layer blocking of the outward invasion of powder, and achieves the final purpose of ultra-clean sealing.

Claims

1. A coaxial sealing structure for the shaft of a horizontal dryer, comprising the shaft (12) and housing (13) of the dryer, characterized in that, The right side of the outer side of the shaft (12) is fixedly fitted with a double spiral pusher bushing (10) that rotates synchronously with it. A combined sealing box (9) is fixed on the box (13). The double spiral pusher bushing (10) is housed in the combined sealing box (9), and the shaft (12) passes through the combined sealing box (9) and is supported at its left end by a bearing. The double spiral pusher bushing (10) and the inner side wall of the combined sealing box (9) are in clearance fit. The combined sealing box (9) has two annular grooves on the inner side wall corresponding to the double spiral pusher bushing (10). Both annular grooves are provided with air holes. The air hole on the right annular groove is connected to a high-pressure air source. The right end of the double spiral pusher bushing (10) is fixed with a spiral blade that extends into the box (13). A spiral structure groove is provided on the outer circumference of the bushing between the spiral blade and the annular groove.

2. The coaxial sealing structure for the shaft of a horizontal dryer according to claim 1, characterized in that, The left end of the combined sealing box (9) is provided with a bearing seat, which supports the shaft (12) through two positioning bearings (4). An inner ring (5) and an outer ring (6) are provided between the two positioning bearings (4). A bearing cover (1) is installed on the outside of the bearing seat, which presses against the outer ring of the positioning bearing (4) on the left. A locking nut (3) is threaded to the left side of the bearing cover (1) on the shaft (12). The locking nut (3) presses against the inner ring of the two positioning bearings (4) and the inner ring (5) of the spacer through a top ring (2) to the right.

3. The coaxial sealing structure for the shaft of a horizontal dryer according to claim 1, characterized in that, A cavity is formed in the middle of the combined sealing box (9), and the left end of the double spiral pusher bushing (10) terminates in the cavity; a packing group (8) is fitted on the right side of the cavity on the double spiral pusher bushing (10), the packing group (8) is composed of multiple sealing rings and is housed in the packing groove of the combined sealing box (9); an annular packing gland (7) is fitted on the left end of the double spiral pusher bushing (10) and presses against the packing group (8), the left end of the packing gland (7) has an outward folded edge, which is fixedly connected to the right side wall of the cavity by fasteners.

4. The coaxial sealing structure for the shaft of a horizontal dryer according to claim 1, characterized in that, The right side of the combined sealing box (9) is fixedly connected and sealed to the box body (13) through an annular corrugated plate (11), and the cross section of the corrugated plate (11) is wavy.

5. The coaxial sealing structure for the shaft of a horizontal dryer according to claim 1, characterized in that, The double helical pusher bushing (10) and the shaft body (12) are welded as a whole.

6. The coaxial sealing structure for the shaft of a horizontal dryer according to claim 1, characterized in that, The air hole on the annular groove on the left side is connected to an external collection device.

7. The coaxial sealing structure for the shaft of a horizontal dryer according to claim 1, characterized in that, The major diameter of the spiral blade and the inner surface of the combined sealing box (9) are in clearance fit.

8. The coaxial sealing structure for the shaft of a horizontal dryer according to claim 1, characterized in that, Near the vent that is connected to the high-pressure gas source, there is also a normally closed inspection port.

9. A sealing method based on the coaxial sealing structure of the horizontal dryer shaft as described in any one of claims 1-8, characterized in that, Includes the following steps: Before starting, first turn on the high-pressure gas source and introduce high-pressure gas into the air hole on the right annular groove. The high-pressure gas forms a bidirectional sealing air curtain in the gap between the double spiral pusher bushing (10) and the combined sealing box (9). Then start the drive device to drive the shaft (12) and the double spiral pusher bushing (10) to rotate; During operation, the air curtain flowing to the left blows out the wear residue generated by the left packing group (8) through the left air hole; the air curtain flowing to the right blocks the powder from entering the gap; at the same time, the rotating spiral blades push most of the powder back into the box (13), and the spiral structure groove pushes the small amount of powder that has entered to the right and is finally pushed back into the box (13) by the spiral blades. When stopping the machine, first stop the drive device, and after the shaft (12) stops rotating, turn off the high-pressure air source.

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