Composite paste packing seal structure

Abstract

The present invention discloses a composite mud-like packing seal structure, which includes a rotating shaft. A stuffing box is sleeved outside the rotating shaft, and the stuffing box is filled with mud-like packing. The outer end opening of the stuffing box is closed by a stuffing gland. The mud-like packing filled in the stuffing box is at least divided into two types according to fluidity. The first mud-like packing with strong fluidity is located in the middle, and the second mud-like packing with weak fluidity is respectively and closely arranged at the inner and outer ends of the first mud-like packing. The beneficial effects of the present invention are as follows: on the premise of maintaining a good sealing effect, it will neither have the problems of easy extrusion and easy loss of the mud-like packing, nor can it keep the rotating shaft rotating with a small rotational resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of sealing materials and structures, and in particular to a composite mud-like packing sealing structure. Background Art

[0002] The paste packing is a new type of dynamic sealing element. The "Proceedings of the 12th International Technical Exchange and Product Exhibition on Friction Sealing Materials" published in May 2010 disclosed "New Type of Dynamic Sealing Element - Paste Packing" by Wang Shijiang, which introduced the paste packing: The paste packing is a paste-like substance made of high-grade synthetic fibers mixed with various oils, greases and adhesives. It is a special mixture of fibers and adhesives. When in use, it needs to be injected into the stuffing box of the equipment through a high-pressure gun. Its basic sealing principle is as follows: During the use of the paste packing, the shear force generated by the movement between the fibers in the middle and the shaft causes the fibers to gradually wind around the shaft as the shaft rotates, and a rotating layer begins to form. As the rotating layer gradually increases, the farther away from the shaft, the smaller the shear force generated by the rotation of the shaft on the fibers, and the worse the ability of the fibers to wind around the shaft. Eventually, after the fibers are a certain distance away from the shaft, they no longer wind around the shaft, thus forming a boundary layer. Outside the boundary layer, the fibers and the inner wall of the stuffing box remain relatively stationary, while in the part of the boundary layer close to the shaft, the paste packing rotates with the shaft. The formation of the boundary layer makes the packing no longer directly rub against the shaft and the inner wall of the stuffing box, but rotate inside the paste packing, thus avoiding the wear of the shaft and the inner wall of the stuffing box. Due to the viscous characteristics of the paste packing, after each boundary layer is formed with the movement of the shaft, both ends of the boundary layer will automatically adhere, making the formation of the boundary layer non-repetitive. In this way, the boundary layer is not just a surface, but a region. In this region, the fibers crisscross and form tiny boundary layers layer by layer. It is these tiny boundary layers that, like a maze, the effect produced by this special structure seals the fluid medium in the boundary layer formed by the packing end ring and the paste packing, thus achieving true zero leakage. Since the raw materials used have a low coefficient of friction, the heat generated by the frictional movement inside the packing is much less than the heat generated by the friction of the braided packing against the shaft. The less the frictional work done, the less the energy consumption. Therefore, the service life of this paste packing is greatly extended, and the energy consumption of the motor is also greatly reduced. Thereafter, the Chinese patent document CN102410215A was published on April 11, 2012, "Layered Shearing Type Sealing Packing for Rotary Pumps and Its Preparation Method", in which asbestos-free mineral fibers, graphite, and lubricating grease are put into a high-speed mixer for mixing, and then fully stirred; the mixture of asbestos-free mineral fibers, graphite, and lubricating grease is kneaded; the kneaded mixture is put into the cavity of a plunger extrusion device for extrusion, and the finished product, the layered shearing type sealing packing for rotary pumps, is obtained after extrusion.Chinese Patent Document CN102433100A was published on May 2, 2012, titled "A Layered Shearing Sealing Filler for Rotary Pumps and Its Preparation Method". Plant fibers are put into a carding machine for carding to make them into fluffy flocculent shapes. The grease and inorganic fillers are subjected to water treatment, then the grease and inorganic fillers are mixed, and then put into a mixer for thorough stirring. The plant fibers are put into the mixer to be mixed with the grease and inorganic fillers. After being evenly mixed, the finished layered shearing sealing filler for rotary pumps is obtained.

[0003] In the art, there have been small-scale applications of mud-like fillers in dynamic sealing structures. Through the feedback of the results of these small-scale applications, the following problems are found: The fluidity of the mud-like filler determines its degree of deformation, and the quality of the degree of deformation determines its sealing effect. A mud-like filler with strong fluidity and good deformation degree can provide a good sealing effect, but conversely, it will also bring problems such as easy extrusion and easy loss. In order to prevent the problems of extrusion and loss, it is necessary to reduce the fluidity of the mud-like filler, but this will also cause the rotational resistance of the rotating shaft to increase and the energy loss to increase. Summary of the Invention

[0004] In order to overcome the above problems, the present invention provides a composite mud-like filler sealing structure, which, on the premise of maintaining a good sealing effect, will neither have the problems of easy extrusion and easy loss of the mud-like filler, nor will it cause the rotating shaft to rotate with a small rotational resistance.

[0005] In order to achieve the object of the invention, the present invention adopts the following technical solutions:

[0006] A composite mud-like filler sealing structure includes a rotating shaft. A stuffing box is sleeved outside the rotating shaft. The stuffing box is filled with a mud-like filler. The outer end opening of the stuffing box is closed by a stuffing gland. The mud-like filler filled in the stuffing box is at least divided into 2 types according to fluidity. The first mud-like filler with strong fluidity is located in the middle, and the second mud-like fillers with weak fluidity are respectively closely arranged at the inner and outer ends of the first mud-like filler.

[0007] In the composite mud-like packing seal structure of this solution, mud-like packing is filled in the stuffing box. The mud-like packing is at least divided into two categories according to fluidity. The first mud-like packing has strong fluidity and is located in the middle. The second mud-like packing has weak fluidity and is divided into inner and outer sections, which are respectively closely located at both ends of the first mud-like packing. In such a structure, the front end and the rear end of the stuffing box are filled with the second mud-like packing with weak fluidity, and the middle section is filled with the first mud-like packing with strong fluidity. The two kinds of mud-like packing respectively focus on undertaking different functions: the second mud-like packing with weak fluidity is responsible for preventing extrusion at both ends, and the first mud-like packing with strong fluidity is responsible for reducing the rotational resistance of the rotating shaft. Due to the inherent characteristic that the mud-like packing only generates circumferential movement when rotating with the rotating shaft, after being completely filled, the first mud-like packing and the second mud-like packing will not cross the common interface and enter each other's interior, resulting in mixing. Therefore, no matter how the rotating shaft rotates, the first mud-like packing and the second mud-like packing always maintain their inherent positions and always undertake their respective different functions. Therefore, by using this solution, on the premise of maintaining a good sealing effect, neither the problem of easy extrusion and easy loss of the mud-like packing will occur, nor can the rotating shaft rotate with a small rotational resistance. If necessary, those skilled in the art can also cite more kinds of mud-like packing, arrange them in sequence according to fluidity, place the one with the best fluidity in the middle of the axis direction, and arrange the ones with poor fluidity from the middle to the ends in the axis direction.

[0008] Preferably, a end ring is provided between the inner end of the stuffing box and the inner end of the second mud-like packing located inside; a end ring is provided between the inner end of the stuffing gland and the outer end of the second mud-like packing located outside. By using end rings at both the inner and outer ends of the stuffing box, the gaps at the inner and outer ends of the stuffing box can be further eliminated through the extrusion deformation of the end rings, avoiding the extrusion of the mud-like packing.

[0009] Preferably, the material of the end ring is polytetrafluoroethylene. Polytetrafluoroethylene has the characteristics of excellent self-lubricating circumferential compensation. Using it as an end ring can effectively reduce the friction force and keep the rotating shaft rotating with a small rotational resistance.

[0010] There are various specific structures of the end ring. Two of them are listed here: As one of the preferences, a spring that can expand and contract radially is embedded in the end ring, and an O-ring installation groove is provided on the outer side surface of the end ring, and an O-ring is embedded in the O-ring installation groove. The specific structure given in Chinese Patent Document CN201531600U can be referred to.

[0011] As a second preference, a sealed elastic cavity is provided in the cross-section of the end ring. The shape of the elastic cavity is V-shaped, and the central axis of the V-shape extends along the axial direction of the end ring; the distance between the upper and lower cavity surfaces of the elastic cavity is larger at the upper end of the V-shape and smaller at the lower end of the V-shape. It is also possible to provide a sealed elastic cavity in the cross-section of the end ring. The shape of the elastic cavity is V-shaped, and the central axis of the V-shape extends along the axial direction of the end ring. The distance between the upper and lower cavity surfaces of the elastic cavity is larger at the upper end of the V-shape and smaller at the two lower ends of the V-shape (taking the inverted V-shape as an example). When axially compressed, the end ring can effectively expand radially, thereby guiding the end ring to improve the sealing effect.

[0012] As a preference, thermal conductive graphite is added to the polytetrafluoroethylene of the end ring material. By adding an appropriate amount of thermal conductive graphite, the thermal conductivity of the end ring material can be improved, and the sealing failure caused by the curling of the polytetrafluoroethylene fiber due to heat can be avoided.

[0013] As a preference, a packing filling hole is provided on the side wall of the stuffing box. The inner end of the packing filling hole corresponds to the area where the first mud-shaped packing is located. When it is necessary to supplement the first mud-shaped packing, it can be filled through the packing filling hole using a filling device. The filling device is an existing technology.

[0014] As a preference, the axial length of the contact surface between the first mud-shaped packing and the rotating shaft is greater than the axial length of the contact surface between the second mud-shaped packing and the rotating shaft. The greater the axial length of the contact surface between the first mud-shaped packing and the rotating shaft, the smaller the rotational resistance of the rotating shaft. On the premise of ensuring the sealing effect, the axial length of the contact surface between the first mud-shaped packing and the rotating shaft can be increased as much as possible.

[0015] As a preference, the filling method of the mud-shaped packing includes the following steps:

[0016] A1. Place the end ring at the inner end into the stuffing box through the outer end opening of the stuffing box;

[0017] B1. Place the preformed annular second mud-shaped packing into the stuffing box through the outer end opening of the stuffing box;

[0018] C1. Place the preformed annular first mud-shaped packing into the stuffing box through the outer end opening of the stuffing box;

[0019] D1. Repeat step B1;

[0020] E1. Place the end ring at the inner end into the stuffing box through the outer end opening of the stuffing box;

[0021] F1. The outer end opening of the stuffing box is sealed by a stuffing gland, and an axial pre-tightening force is applied. For the above structure, this solution presents a method of filling different fluidity mud-like packing into the stuffing box in layers. The plasticity of the mud-like packing can be fully utilized. Each layer of mud-like packing is pre-formed into a suitable ring according to the size of the stuffing box, and then the end ring at the inner end, the annular second mud-like packing, the annular first mud-like packing, the annular second mud-like packing, and the end ring at the outer end are sequentially placed into the stuffing box to pre-position these five structures in the stuffing box. Then, the outer end opening of the stuffing box is sealed by a stuffing gland, and finally, a pre-tightening force towards the inner side of the stuffing box is applied to the stuffing gland by means of thread fastening or the like to maintain an appropriate pressure of the mud-like packing in the stuffing box. Those skilled in the art can adjust the magnitude of the pre-tightening force according to factors such as the pressure of the sealed object, the fluidity of the mud-like packing, and the objective conditions of the working environment. The advantage of this method is fast filling speed and high efficiency.

[0022] Preferably, a stuffing filling hole is provided in the middle of the side wall of the stuffing box. The stuffing filling hole is opened in the middle of the side wall of the stuffing box and has two functions. One is that during initial installation, mud-like packing can be filled into the stuffing box through the stuffing filling hole, and the other is that during later use, the pressure of the mud-like packing in the stuffing box can be adjusted through the stuffing filling hole to adapt to different working environments and different sealing requirements. For continuously used equipment and devices, this solution can be adjusted without shutting down and disassembling the sealing structure, which is of particular positive significance. The stuffing filling hole is provided with a closing structure such as a hole plug. After filling is completed, the stuffing filling hole can be closed with the hole plug.

[0023] Preferably, for the composite mud-like packing sealing structure provided with a stuffing filling hole, the filling method of its mud-like packing includes the following steps:

[0024] A2. Place the end ring at the inner end into the stuffing box from the outer end opening of the stuffing box;

[0025] B2. Rotate the rotating shaft, and at the same time, inject the second mud-like packing into the stuffing box through the stuffing filling hole so that the second mud-like packing forms a cylindrical shape in the middle of the rotating shaft;

[0026] C2. Continuously rotate the rotating shaft, and at the same time, inject the first mud-like packing into the stuffing box through the stuffing filling hole, divide the second mud-like packing in the stuffing box axially into two parts, and continuously squeeze the two parts of the second mud-like packing towards both ends;

[0027] D2. When the stuffing box is filled with mud-like packing, stop injecting the first mud-like packing;

[0028] E2. The closed packing filling hole, the outer end opening of the stuffing box is sealed by the packing gland, and an axial pre-tightening force is applied. For the structure provided with the packing filling hole, this solution also gives the method of filling different fluidity mud-like packings into the stuffing box in layers. First, place the end ring at the inner end into the inner end of the stuffing box, then inject the second mud-like packing into the stuffing box through the packing filling hole, and rotate the rotating shaft while injecting. Utilizing the inherent surface tension of the mud-like packing, the second mud-like packing forms an annular structure in the stuffing box with the inner side gripping the rotating shaft and the outer side closely adhering to the inner wall of the stuffing box. The opening of the packing filling hole is located at the axial middle of this annular structure. Then continue to inject the first mud-like packing into the stuffing box through the packing filling hole, and still need to rotate the rotating shaft while injecting. Since the inner end of the packing filling hole opens into the annular structure formed by the second mud-like packing, the injection action of the first mud-like packing cuts the second mud-like packing circumferentially. As more and more of the first mud-like packing is injected, the second mud-like packing is divided into two parts and is respectively squeezed towards the two axial ends. As the first mud-like packing is continuously injected, the volume of the first mud-like packing in the middle becomes larger and larger, and the second mud-like packing at both ends continuously translates towards the ends until the stuffing box is filled. Finally, seal the packing filling hole, then seal the outer end opening of the stuffing box with the packing gland, and apply the preset axial pre-tightening force. The advantage of this method is that the first mud-like packing and the second mud-like packing are installed without gaps and the filling effect is good.

[0029] The beneficial effects of the present invention are: on the premise of maintaining a good sealing effect, neither the problem of easy extrusion and easy loss of the mud-like packing will occur, nor can the rotating shaft rotate with a small rotational resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic structural diagram of Embodiment 1 of the present invention;

[0031] Figure 2 is a schematic structural diagram of Embodiment 2 of the present invention;

[0032] Figure 3 is a schematic cross-sectional view of an end ring;

[0033] Figure 4 is a schematic cross-sectional view of another end ring.

[0034] In the figure: 1 rotating shaft, 2 stuffing box, 21 packing filling hole, 3 packing gland, 4 fastening bolt, 5 end ring, 51 spring, 52 O-ring seal, 53 elastic cavity, 61 first mud-like packing, 62 second mud-like packing. DETAILED DESCRIPTION OF THE INVENTION

[0035] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly explained and described below with reference to the accompanying drawings. However, the following embodiments are only the preferred embodiments of the present invention, rather than all embodiments. Based on the embodiments in the implementation manners, other embodiments obtained by those skilled in the art without creative efforts all fall within the protection scope of the present invention.

[0036] Embodiment 1: As Figure 1 shown, a composite mud-like packing seal structure includes a rotating shaft 1. A stuffing box 2 is sleeved outside the rotating shaft 1. The left end inside the stuffing box 2 is the inner end, and only a through hole for the rotating shaft to pass through is reserved at the inner end. The right end is the outer end, and the outer end is an open end. An end ring 5 is tightly installed at the inner end of the stuffing box 2, and an end ring 5 is also installed at the outer end. The cross-sectional dimension of the end ring 5 is equivalent to that of the stuffing box 2. Mud-like packing is filled between the inner and outer end rings 5. The right side of the outer end ring 5 is closed by a packing gland 3 and fastened by fastening bolts 4.

[0037] The mud-like packing filled in the stuffing box 2 is classified into 2 categories according to fluidity. The first mud-like packing 61 with strong fluidity is located in the middle, and the second mud-like packing 62 with weak fluidity is respectively tightly arranged at the inner and outer ends of the first mud-like packing 61. Therefore, from left to right in the stuffing box 2 are arranged as follows: end ring 5, second mud-like packing 62, first mud-like packing 61, second mud-like packing 62, end ring 5. Among them, the axial length of the contact surface between the first mud-like packing 61 and the rotating shaft 1 is greater than the axial length of the contact surface between the second mud-like packing 62 and the rotating shaft 1.

[0038] In this example, the material of the end ring 5 is polytetrafluoroethylene containing 5% heat-conducting graphite, and a spring 51 that can expand and contract radially is embedded therein. An O-ring installation groove is provided on the outer side surface of the end ring 5, and an O-ring 52 is embedded in the O-ring installation groove. For the specific structure, reference can be made to the specific structure given in Chinese Patent Document CN201531600U. The spring 51 of the inner end ring 5 opens to the left, and the spring 51 of the outer end ring 5 opens to the right. For the specific structure of the end ring 5, reference can be made to Figure 3 .

[0039] For the composite mud-like packing seal structure in this example, the filling method of the mud-like packing includes the following steps:

[0040] A1, Place the end ring 5 at the inner end into the stuffing box 2 from the open end at the outer end of the stuffing box 2;

[0041] B1, Place the preformed annular second mud-like packing 62 into the stuffing box 2 from the open end at the outer end of the stuffing box 2;

[0042] C1, Place the preformed annular first mud-like packing 61 into the stuffing box 2 from the open end at the outer end of the stuffing box 2;

[0043] D1. Repeat step B1;

[0044] E1. Insert the end ring 5 at the outer end into the stuffing box 2 through the opening at the outer end of the stuffing box 2;

[0045] F1. Close the opening at the outer end of the stuffing box 2 with the stuffing gland 3 and apply an axial pre-tightening force through the fastening bolt 4.

[0046] Example 2: As Figure 2 shown, it is another composite mud-like packing sealing structure. A stuffing injection hole 21 is provided in the middle of the side wall of the stuffing box 2, and the stuffing injection hole 21 is equipped with a cover.

[0047] In this example, the structure of the end ring 5 is as Figure 4 shown. A sealed elastic cavity 53 is provided in the cross-section. The number of elastic cavities 53 is 2 arranged vertically, and the shape is an inverted V shape. The central axis of the V shape extends along the axial direction of the end ring 5. The distance between the upper and lower cavity surfaces of the elastic cavity 53 is large at the upper end of the V shape and small at the lower end of the V shape.

[0048] The rest is the same as in Example 1.

[0049] For the composite mud-like packing sealing structure in this example, the filling method of the mud-like packing includes the following steps:

[0050] A2. Insert the end ring 5 at the inner end into the stuffing box 2 through the opening at the outer end of the stuffing box 2;

[0051] B2. Rotate the rotating shaft 1, and at the same time inject the second mud-like packing 62 into the stuffing box 2 through the stuffing injection hole 2) so that the second mud-like packing 62 forms a cylindrical shape in the middle of the rotating shaft 1, with its inner side wall wrapping the rotating shaft 1 and its outer side wall closely adhering to the inner wall of the stuffing box 2;

[0052] C2. Continuously rotate the rotating shaft 1, and at the same time inject the first mud-like packing 61 into the stuffing box 2 through the stuffing injection hole 21, divide the second mud-like packing 62 in the stuffing box 2 into two parts axially, and continuously squeeze the two parts of the second mud-like packing 62 towards both ends;

[0053] D2. When the stuffing box 2 is filled with the mud-like packing, stop injecting the first mud-like packing 61;

[0054] E2. Use the cover to close the stuffing injection hole 21, close the opening at the outer end of the stuffing box 2 with the stuffing gland 3, and apply an axial pre-tightening force through the fastening bolt 4.

[0055] For the composite mud-like packing seal structure in this example, after being used for a period of time, the packing filling hole 21 can be opened to inject an appropriate amount of the first mud-like packing 61, so as to compensate for the wear of the mud-like packing during daily use. It is also possible to extract or inject the first mud-like packing 61 when the working conditions and sealing requirements change significantly, so as to adjust the sealing effect.

Claims

1. A composite mud-like packing seal structure, comprising a rotating shaft (1), a stuffing box (2) is sleeved outside the rotating shaft (1), the stuffing box (2) is filled with mud-like packing, and the outer end opening of the stuffing box (2) is closed by a stuffing gland (3), characterized in that, The paste-like packing filled in the stuffing box (2) is at least divided into two categories according to fluidity. The first paste-like packing (61) with strong fluidity is located in the middle, and the second paste-like packing (62) with weak fluidity is respectively and closely arranged at the inner and outer ends of the first paste-like packing (61); An end ring (5) is provided between the inner end of the stuffing box (2) and the inner end of the second paste-like packing (62) located inside; an end ring (5) is provided between the inner end of the stuffing gland (3) and the outer end of the second paste-like packing (62) located outside; A sealed elastic cavity (53) is provided in the cross-section of the end ring (5); The shape of the elastic cavity (53) is V-shaped.

2. The composite mud-like packing seal structure according to claim 1, wherein, The central axis of the V shape extends along the axial direction of the end ring (5); the distance between the upper and lower cavity surfaces of the elastic cavity (53) is large at the upper end of the V shape and small at the lower end of the V shape.

3. The composite mud-like packing seal structure according to claim 1, characterized in that, The material of the end ring (5) is polytetrafluoroethylene.

4. The composite mud-like packing seal structure according to claim 3, characterized in that, Thermally conductive graphite is added to the polytetrafluoroethylene of the material of the end ring (5).

5. A composite mud-like packing seal structure according to claim 1 or 2, characterized in that, The axial length of the contact surface where the first paste-like packing (61) contacts the rotating shaft (1) is greater than the axial length of the contact surface where the second paste-like packing (62) contacts the rotating shaft (1).

6. The composite mud-like packing seal structure according to claim 5, characterized in that, The method for filling the paste-like packing includes the following steps: A1. Place the end ring (5) at the inner end into the stuffing box (2) from the outer end opening of the stuffing box (2); B1. Place the preformed ring-shaped second paste-like packing (62) into the stuffing box (2) from the outer end opening of the stuffing box (2); C1. Place the preformed ring-shaped first paste-like packing (61) into the stuffing box (2) from the outer end opening of the stuffing box (2); D1. Repeat step B1; E1. Place the end ring (5) at the outer end into the stuffing box (2) from the outer end opening of the stuffing box (2); F1. Seal the outer end opening of the stuffing box (2) with the stuffing gland (3) and apply an axial pre-tightening force.

7. A composite mud-like packing seal structure according to claim 1 or 2, characterized in that, A stuffing filling hole (21) is provided in the middle of the side wall of the stuffing box (2).

8. The composite mud-like packing seal structure according to claim 7, characterized in that, The method for filling the paste-like packing includes the following steps: A2. Place the end ring (5) at the inner end into the stuffing box (2) from the outer end opening of the stuffing box (2); B2. Rotate the rotating shaft (1), and at the same time inject the second paste-like packing (62) into the stuffing box (2) through the stuffing filling hole (21) so that the second paste-like packing (62) forms a cylindrical shape in the middle of the rotating shaft (1); C2. Continuously rotate the rotating shaft (1), and at the same time inject the first paste-like packing (61) into the stuffing box (2) through the stuffing filling hole (21), divide the second paste-like packing (62) in the stuffing box (2) into two parts axially, and continuously squeeze the two parts of the second paste-like packing (62) towards both ends; D2. When the stuffing box (2) is filled with the paste-like packing, stop injecting the first paste-like packing (61); E2. Seal the stuffing filling hole (21), seal the outer end opening of the stuffing box (2) with the stuffing gland (3) and apply an axial pre-tightening force.

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