Tubular flow dust-containing ventilation and exhaust mechanism

Abstract

The invention relates to the technical field of pipeline cleaning, and discloses a tubular flow dust-containing ventilation and exhaust mechanism which comprises an exhaust pipe, an air inlet pipe is fixedly connected to the side wall of the exhaust pipe and used for introducing dust-containing gas, one end of the exhaust pipe is fixedly connected with a blockage clearing pipe, and a whistle type sounder is arranged in the blockage clearing pipe. A whistle type sounder is connected with an air source through an air supply pipe, compressed air in the air source passes through the whistle type sounder, flows at a high speed and vibrates under the action of the whistle type sounder, the vibration is spread out in the form of sound waves through a gas medium, and the frequency range of the vibration is generally dozens of hertz to several kilohertz. Acoustic waves enable accumulated dust particles to vibrate in the propagation process, due to the fact that the binding force between the accumulated dust particles and the binding force between the accumulated dust and the heated surface are relatively weak, under the action of the acoustic waves, the binding force is damaged, and the accumulated dust particles can fall off from the inner wall of the exhaust pipe.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline cleaning, and in particular to a tubular flow dust-containing ventilation and exhaust mechanism. Background Art

[0002] Sonic soot blower is a device used for soot blowing in main pipelines. It is mainly used in heating furnaces, atmospheric furnaces, waste heat furnaces, power station boilers and other heat exchangers and denitration reactors in power plants that use pulverized coal, fuel oil and various gases as fuels. It is used to remove the soot accumulation on the superheater, convection section, economizer, preheater, denitration reactor catalyst surface and other parts. Diaphragm type soot blower is widely used in denitration reactor catalysts and boiler heat exchangers due to its high sound intensity, maintenance-free and flexible installation.

[0003] The prior art, such as the Chinese patent "CN209819566U", provides a sonic soot blower, including a sonic generator, a sonic outlet pipe, a universal elbow connected between the sonic outlet pipe and the sonic generator, and a sealing device arranged between the sonic outlet pipe and the universal elbow; the end of the universal elbow is inserted into the sonic outlet pipe, and the outer wall of the universal elbow is against the inner wall of the sonic outlet pipe; the sealing device includes an elastic ring sleeved on the universal elbow, an elastic ring sleeved on and fixed to the elastic ring, a clamping ring sleeved on the universal elbow and threadedly connected to the outer wall of the universal elbow, and a clamping part sleeved on the elastic ring for clamping the elastic ring, and the clamping ring is arranged on the side of the elastic ring away from the sonic outlet pipe. The utility model has the following effects: the scheme uses a new mechanical structure to achieve a good sealing effect between the sonic outlet pipe and the universal elbow in the sonic soot blower, effectively reducing the leakage of compressed air and improving the working performance of the sonic soot blower.

[0004] In the prior art, the motor and rotor of a whistle-type sound generator need regular maintenance. The motor should be regularly checked for lubrication, and grease should be added every six months. The blades on the rotor should be checked for wear and deformation. The blades can be cleaned and balanced every year or so to ensure that they rotate smoothly and produce stable sound waves. However, since the sound generator can generally be connected to the pipeline through a flange, each installation and disassembly is more troublesome, and repeated disassembly of the installation flange will cause wear at the connection, resulting in a decrease in its sealing performance. Summary of the invention

[0005] The purpose of the present invention is to provide a tubular flow dust-containing ventilation and exhaust mechanism in order to solve the above-mentioned problems and overcome the defects of the prior art, as described in detail below.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a tubular flow dust-containing ventilation and exhaust mechanism, comprising an exhaust pipe, a side wall of the exhaust pipe is fixedly connected to an air inlet pipe for receiving dust-containing gas, and one end of the exhaust pipe is fixedly connected to a clearing pipe for clearing dust attached to the inner wall of the exhaust pipe;

[0008] A sealing mechanism is provided at the connection between the exhaust pipe and the clearing pipe, for improving the air tightness of the connection between the exhaust pipe and the clearing pipe;

[0009] A connecting mechanism is provided at the connection between the exhaust pipe and the clearing pipe, which is used for connecting the exhaust pipe and the clearing pipe;

[0010] The inner wall of the clearing pipe is fixedly connected with a whistle-type sound generator, which is used to generate high-speed flow and vibrating airflow and inject it into the interior of the exhaust pipe.

[0011] Preferably, an end cap is fixedly connected to the clearing pipe at one end away from the exhaust pipe, and the air supply pipe connected to the rotary flute sounder passes through the end cap and extends to the outside of the clearing pipe for connecting to an air source, and the gas of the air source should be an inert gas.

[0012] Preferably, the gas supply pipe is provided with a check valve for preventing gas backflow, and the gas supply pipe is provided with a pressure relief valve for relieving pressure in the gas supply pipe.

[0013] Preferably, the sealing mechanism comprises a disc, the disc is fixedly connected to one end of the exhaust pipe, one end of the clearing pipe corresponding to the disc is fixedly connected to a connecting disc, and the connecting disc is fixedly connected to the disc.

[0014] Preferably, an annular groove is provided on one side of the corresponding circular disc of the connecting disc, a sealing ring is slidably connected to the inner wall of the annular groove, a spring is connected between the sealing ring and the inner wall of the annular groove, and a groove for embedding the sealing ring is provided at the position corresponding to the sealing ring on the circular disc.

[0015] Preferably, the connecting mechanism comprises a plurality of sets of articulated rods, which are hinged at a side of the connecting disk away from the circular disk and extend to the outside of the connecting disk. The articulated rods are located at a side of the circular disk away from the connecting disk and are fixedly connected with locking buckles for clamping the circular disk, and a groove for embedding the locking buckles is provided on the surface of the circular disk.

[0016] Preferably, the outer wall of the clearing pipe has an axially rotatable swivel, the inner wall of the swivel has an arc groove corresponding to the position of the hinged rod, the inner wall of the arc groove is slidably connected with a guide column, and the guide column is fixedly connected to the hinged rod at the corresponding position.

[0017] Preferably, a first end face ratchet is fixedly connected to the side of the rotating ring away from the connecting disk, the end face of the first end face ratchet is provided with a second end face ratchet that cooperates with each other, the inner wall of the second end face ratchet is fixedly connected with a connecting key, and a key groove for the sliding of the connecting key is provided on the outer wall of the clearing pipe at the position corresponding to the connecting key.

[0018] Preferably, a push block is fixedly connected to a side of the second end face ratchet away from the connecting plate, and the outer wall of the clearing pipe is threadedly connected to a threaded sleeve via an external thread, and the end face of the external thread abuts against the push block.

[0019] The beneficial effects are:

[0020] 1. The present invention connects dust-containing gas through an air inlet pipe arranged on the side wall of the exhaust pipe, and the gas is discharged from the exhaust pipe. A clearing pipe is connected at one end of the exhaust pipe, and a rotary flute-type sound generator is arranged inside the clearing pipe. The rotary flute-type sound generator is connected to an air source through an air supply pipe. The compressed air in the air source passes through the rotary flute-type sound generator. Under the action of the rotary flute-type sound generator, the compressed air in the air source flows and vibrates at a high speed. This vibration is transmitted through the gas medium in the form of sound waves, and the frequency range is generally between tens of hertz and several thousand hertz. The sound waves cause the dust particles to vibrate during the propagation process. Since the binding forces between the dust particles and between the dust and the heating surface are relatively weak, these binding forces are destroyed under the action of the sound waves, and the dust particles will fall off from the inner wall of the exhaust pipe, thereby achieving the purpose of cleaning.

[0021] 2. The present invention can improve the overall sealing of the pipeline and avoid the safety hazard of gas leakage by arranging a sealing mechanism at the connection between the clearing pipe and the exhaust pipe. The sealing of the connection between the clearing pipe and the exhaust pipe can be improved by the larger fitting area between the disc and the connecting disc. A sealing ring is arranged in the annular groove of the connecting disc and supported by a spring. When the disc and the connecting disc are fitted together, the sealing ring is always pressed against the disc under the action of the spring tension, thereby further improving the sealing and avoiding the situation where the sealing ring is worn out after repeated disassembly, resulting in a loose fit.

[0022] 3. When installing the blockage clearing pipe according to the present invention, the connecting disk is pressed against the circular disk, and the swivel is pushed to rotate. The articulated rod connected to the guide column is pushed to rotate through the arc groove on the swivel, so that the locking buckle connected to the articulated rod is embedded in the groove on the surface of the circular disk to keep the circular disk and the connecting disk in a tight state. After the locking buckle is embedded in the groove on the surface of the circular disk, the threaded sleeve is moved on the external thread of the blockage clearing pipe by twisting the threaded sleeve, and the push block is pushed to connect the second end face ratchet to clamp the first end face ratchet on the swivel, so as to facilitate the swivel, and through the collaborative limiting method, the stability of the overall structure is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a structural schematic diagram of the overall appearance of the present invention;

[0025] Figure 2 It is a schematic diagram of the internal structure of the pipe clearing blockage in the present invention;

[0026] Figure 3 It is a schematic diagram of the structure of the locking buckle in the present invention;

[0027] Figure 4 The present invention Figure 3 A schematic diagram of the structure of the middle locking buckle area;

[0028] Figure 5 It is a structural schematic diagram of the sealing mechanism in the present invention;

[0029] Figure 6 The present invention Figure 1 A schematic structural diagram of the ratchet region of the first end face;

[0030] Figure 7 The present invention Figure 2 A schematic structural diagram of the ratchet region of the first end face;

[0031] Figure 8 It is a schematic structural diagram of the first end face ratchet and the second end face ratchet in the present invention.

[0032] The accompanying drawings are described as follows: 1. Exhaust pipe; 2. Inlet pipe; 3. Sealing mechanism; 31. Disc; 32. Connecting disc; 321. Annular groove; 322. Sealing ring; 323. Spring; 4. Connecting mechanism; 41. Articulated rod; 42. Locking buckle; 43. Guide column; 44. Swivel; 45. Arc groove; 46. First end face ratchet; 47. Second end face ratchet; 471. Keyway; 472. Connecting key; 473. Push block; 48. External thread; 49. Threaded sleeve; 5. Clearing pipe; 51. Rotary flute sounder; 52. End cover; 53. Air supply pipe; 54. Check valve; 55. Pressure relief valve. DETAILED DESCRIPTION

[0033] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0034] See also Figure 1 - Figure 8 As shown, the present invention provides a tubular flow dust-containing ventilation and exhaust mechanism, including an exhaust pipe 1, a side wall of the exhaust pipe 1 is fixedly connected to an air inlet pipe 2 for receiving dust-containing gas, one end of the exhaust pipe 1 is fixedly connected to a clearing pipe 5 for cleaning dust attached to the inner wall of the exhaust pipe 1, a sealing mechanism 3 is provided at the connection between the exhaust pipe 1 and the clearing pipe 5, for improving the airtightness of the connection between the exhaust pipe 1 and the clearing pipe 5, a connecting mechanism 4 is provided at the connection between the exhaust pipe 1 and the clearing pipe 5, and the inner wall of the clearing pipe 5 is fixedly connected to the exhaust pipe 1. A whistle-type sound generator 51 is connected to generate a high-speed flow and vibrating airflow, and inject it into the exhaust pipe 1. The end of the clearing pipe 5 away from the exhaust pipe 1 is fixedly connected to an end cap 52. The air supply pipe 53 connected to the whistle-type sound generator 51 passes through the end cap 52 and extends to the outside of the clearing pipe 5 for connecting to an air source. The gas of the air source should be an inert gas. A check valve 54 is provided on the air supply pipe 53 to prevent gas backflow. A pressure relief valve 55 is provided on the air supply pipe 53 to relieve the pressure of the air supply pipe 53. The pipe 2 is connected to the dust-containing gas, and the gas is discharged from the exhaust pipe 1. A clearing pipe 5 is connected to one end of the exhaust pipe 1. A flute-type sound generator 51 is arranged inside the clearing pipe 5. The flute-type sound generator 51 is connected to the air source through the air supply pipe 53. The compressed air in the air source passes through the flute-type sound generator 51. Under the action of the flute-type sound generator 51, it flows and vibrates at a high speed. This vibration is transmitted through the gas medium in the form of sound waves. The frequency range is generally between tens of hertz and several thousand hertz. The sound waves cause the dust particles to vibrate during the propagation process. The bonding forces between the dust particles and between the dust and the heated surface are relatively weak. Under the action of sound waves, these bonding forces are destroyed, and the dust particles will fall off from the inner wall of the exhaust pipe 1, thereby achieving the purpose of cleaning. If an inert gas is used to connect the air supply pipe 53 to the gas source, when treating flammable and explosive gases such as silane, the amount of dust attached to the pipe wall can be reduced through the action of sound wave vibration, or the dust already attached to the pipe wall can be peeled off from the pipe wall and carried away by the fluid in the exhaust pipe 1, thereby reducing the risk of pipeline blockage and the frequency of maintenance, thereby improving pipeline safety.

[0035] In this embodiment, please refer to Figure 3 , Figure 5The sealing mechanism 3 includes a disc 31, which is fixedly connected to one end of the exhaust pipe 1, and a connecting disc 32 is fixedly connected to one end of the clearing pipe 5 corresponding to the disc 31, and the connecting disc 32 is fixedly connected to the disc 31, and an annular groove 321 is provided on one side of the connecting disc 32 corresponding to the disc 31, and a sealing ring 322 is slidably connected to the inner wall of the annular groove 321, and a spring 323 is connected to the position between the sealing ring 322 and the inner wall of the annular groove 321, and a groove for embedding the sealing ring 322 is provided on the disc 31 corresponding to the sealing ring 322. By arranging a sealing ring 321 at the connection between the clearing pipe 5 and the exhaust pipe 1 The sealing mechanism 3 can improve the overall sealing of the pipeline and avoid the safety hazard of gas leakage. The larger fitting area between the disc 31 and the connecting disc 32 can improve the sealing of the connection between the clearing pipe 5 and the exhaust pipe 1. A sealing ring 322 is provided in the annular groove 321 of the connecting disc 32 and supported by a spring 323. When the disc 31 and the connecting disc 32 are fitted together, the sealing ring 322 is always pressed against the disc 31 under the action of the tension of the spring 323, thereby further improving the sealing and avoiding the situation where the sealing ring 322 is worn out after repeated disassembly, resulting in a loose fit.

[0036] For further information, see Figure 2 , Figure 3 , Figure 4 , Figure 6 The connecting mechanism 4 includes a plurality of sets of hinged rods 41, which are hinged on the side of the connecting disk 32 away from the disk 31 and extend to the outside of the connecting disk 32. The hinged rods 41 are located at the side of the disk 31 away from the connecting disk 32, and are fixedly connected with locking buckles 42 for clamping the disk 31. The surface of the disk 31 is provided with a groove for embedding the locking buckles 42. The outer wall of the clearing pipe 5 is axially rotated with a swivel 44, and the inner wall of the swivel 44 corresponds to the position of the hinged rod 41. An arc groove 45 is provided, and the inner wall of the arc groove 45 is slidably connected with a guide column 43, and the guide column 43 is fixedly connected to the hinge rod 41 at the corresponding position. When installing the clearing pipe 5, the connecting plate 32 is pressed against the disc 31, and the rotating ring 44 is pushed to rotate. The hinge rod 41 connected to the guide column 43 is pushed to rotate through the arc groove 45 on the rotating ring 44, so that the locking buckle 42 connected to the hinge rod 41 is embedded in the groove on the surface of the disc 31 to keep the disc 31 and the connecting plate 32 in a close contact state.

[0037] For further information, see Figure 1 , Figure 2 , Figure 6 , Figure 7 , Figure 8The first end face ratchet 46 is fixedly connected to the side of the swivel 44 away from the connecting disk 32, and the end face of the first end face ratchet 46 is provided with a second end face ratchet 47 that cooperates with each other. The inner wall of the second end face ratchet 47 is fixedly connected with a connecting key 472, and a key groove 471 for sliding the connecting key 472 is provided at the position of the outer wall of the clearing pipe 5 corresponding to the connecting key 472. The second end face ratchet 47 is fixedly connected to the side of the second end face ratchet 47 away from the connecting disk 32. The outer wall of the clearing pipe 5 is threadedly connected with a threaded sleeve 49 through an external thread 48, and the end face of the external thread 48 is against the push block 473. After the locking buckle 42 is embedded in the groove on the surface of the disc 31, the threaded sleeve 49 is screwed to make the threaded sleeve 49 move on the external thread 48 of the clearing pipe 5, and the push block 473 is pushed to connect the second end face ratchet 47 to clamp the first end face ratchet 46 on the swivel 44, so as to facilitate the swivel 44, and improve the stability of the overall structure through the collaborative limiting method.

[0038] How it works

[0039] When in use, by providing a sealing mechanism 3 at the connection between the clearing pipe 5 and the exhaust pipe 1, the sealing performance of the entire pipeline can be improved to avoid the safety hazard of gas leakage. The larger fitting area between the disc 31 and the connecting disc 32 can improve the sealing performance of the connection between the clearing pipe 5 and the exhaust pipe 1. By providing a sealing ring 322 in the annular groove 321 of the connecting disc 32 and supporting it with a spring 323, when the disc 31 and the connecting disc 32 are fitted together, the sealing ring 322 is always pressed against the disc 31 under the action of the tension of the spring 323, thereby further improving the sealing performance and avoiding the sealing ring 322 from being worn out after repeated disassembly. In order to prevent the unclosed fit, when installing the clearing pipe 5, the connecting plate 32 is pressed against the disc 31, and the rotating ring 44 is pushed to rotate. The hinged rod 41 connected to the guide column 43 is pushed to rotate through the arc groove 45 on the rotating ring 44, so that the locking buckle 42 connected to the hinged rod 41 is embedded in the groove on the surface of the disc 31 to keep the disc 31 and the connecting plate 32 in a close fit. After the locking buckle 42 is embedded in the groove on the surface of the disc 31, the threaded sleeve 49 is screwed to move the threaded sleeve 49 on the external thread 48 of the clearing pipe 5, and the push block 473 is pushed to connect the second end face ratchet 47 to clamp the first end face ratchet 46 on the rotating ring 44, so as to facilitate the rotation of the rotating ring 44. By means of collaborative limiting, the stability of the overall structure is improved, and the larger fitting area between the disc 31 and the connecting disc 32 can improve the sealing of the connection between the clearing pipe 5 and the exhaust pipe 1, and by providing a sealing ring 322 in the annular groove 321 of the connecting disc 32 and supporting it through a spring 323, when the disc 31 and the connecting disc 32 fit together, the sealing ring 322 always presses against the disc 31 under the action of the tension of the spring 323, thereby further improving the sealing, and the dust-containing gas is connected to the intake pipe 2 provided on the side wall of the exhaust pipe 1, and the gas is discharged from the exhaust pipe 1, and the clearing pipe 5 is connected at one end of the exhaust pipe 1. A rotary flute sounder 51 is arranged inside the clearing pipe 5, and the rotary flute sounder 51 is connected to an air source through an air supply pipe 53. The compressed air in the air source passes through the rotary flute sounder 51. Under the action of the rotary flute sounder 51, it flows and vibrates at a high speed. This vibration is transmitted through the gas medium in the form of sound waves, and its frequency range is generally between tens of hertz and several thousand hertz. The sound waves cause the dust particles to vibrate during the propagation process. Since the binding forces between the dust particles and between the dust and the heating surface are relatively weak, these binding forces are destroyed under the action of the sound waves, and the dust particles will fall off from the inner wall of the exhaust pipe 1, thereby achieving the purpose of cleaning.

[0040] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A tubular flow dust-containing ventilation and exhaust mechanism, characterized in that: It comprises an exhaust pipe (1), the side wall of the exhaust pipe (1) is fixedly connected to an air inlet pipe (2) for receiving dust-containing gas, and one end of the exhaust pipe (1) is fixedly connected to a clearing pipe (5) for clearing dust attached to the inner wall of the exhaust pipe (1); A sealing mechanism (3) is provided at the connection between the exhaust pipe (1) and the clearing pipe (5) for improving the airtightness of the connection between the exhaust pipe (1) and the clearing pipe (5); A connecting mechanism (4) is provided at the connection between the exhaust pipe (1) and the clearing pipe (5), and is used for connecting the exhaust pipe (1) and the clearing pipe (5); The inner wall of the clearing pipe (5) is fixedly connected with a whistle-type sound generator (51) for generating a high-speed flowing and vibrating airflow and injecting it into the interior of the exhaust pipe (1).

2. According to claim 1, a tubular flow dust-containing ventilation and exhaust mechanism is characterized in that: An end cap (52) is fixedly connected to one end of the clearing pipe (5) away from the exhaust pipe (1); an air supply pipe (53) connected to the whistle-type sound generator (51) passes through the end cap (52) and extends to the outside of the clearing pipe (5) for connecting to an air source, and the gas of the air source should be an inert gas.

3. According to claim 2, a tubular flow dust-containing ventilation and exhaust mechanism is characterized in that: The gas supply pipe (53) is provided with a check valve (54) for preventing gas from flowing back, and the gas supply pipe (53) is provided with a pressure relief valve (55) for relieving pressure in the gas supply pipe (53).

4. According to claim 1, a tubular flow dust-containing ventilation and exhaust mechanism is characterized in that: The sealing mechanism (3) comprises a disc (31), wherein the disc (31) is fixedly connected to one end of the exhaust pipe (1), and the end of the clearing pipe (5) corresponding to the disc (31) is fixedly connected to a connecting disc (32), and the connecting disc (32) is fixedly connected to the disc (31).

5. A tubular flow dust-containing ventilation and exhaust mechanism according to claim 4, characterized in that: An annular groove (321) is provided on one side of the circular disc (31) corresponding to the connecting disc (32); a sealing ring (322) is slidably connected to the inner wall of the annular groove (321); a spring (323) is connected between the sealing ring (322) and the inner wall of the annular groove (321); and a groove for embedding the sealing ring (322) is provided at a position on the circular disc (31) corresponding to the sealing ring (322).

6. A tubular flow dust-containing ventilation and exhaust mechanism according to claim 1, characterized in that: The connection mechanism (4) comprises a plurality of sets of hinged rods (41), wherein the plurality of sets of hinged rods (41) are hingedly connected to a side of the connection disk (32) away from the circular disk (31) and extend to the outside of the connection disk (32), and the hinged rods (41) are located at a side of the circular disk (31) away from the connection disk (32), and are all fixedly connected with locking buckles (42) for clamping the circular disk (31), and a groove for embedding the locking buckles (42) is provided on the surface of the circular disk (31).

7. A tubular flow dust-containing ventilation and exhaust mechanism according to claim 6, characterized in that: The outer wall of the blockage clearing pipe (5) is provided with a swivel ring (44) for axial rotation, and an arc groove (45) is provided on the inner wall of the swivel ring (44) at a position corresponding to the hinge rod (41), and the inner wall of the arc groove (45) is slidably connected with a guide column (43), and the guide column (43) is fixedly connected to the hinge rod (41) at the corresponding position.

8. A tubular flow dust-containing ventilation and exhaust mechanism according to claim 7, characterized in that: A first end face ratchet (46) is fixedly connected to a side of the rotating ring (44) away from the connecting plate (32); a second end face ratchet (47) is provided on the end face of the first end face ratchet (46) to cooperate with each other; a connecting key (472) is fixedly connected to the inner wall of the second end face ratchet (47); and a key groove (471) for the connecting key (472) to slide is provided at a position of the outer wall of the clearing pipe (5) corresponding to the connecting key (472).

9. A tubular flow dust-containing ventilation and exhaust mechanism according to claim 8, characterized in that: A push block (473) is fixedly connected to the side of the second end face ratchet (47) away from the connecting plate (32); the outer wall of the clearing pipe (5) is threadedly connected to a threaded sleeve (49) via an external thread (48), and the end face of the external thread (48) abuts against the push block (473).

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