Explosion-proof dust remover for environment-friendly engineering construction

Abstract

The invention relates to the technical field of dust removal equipment, in particular to an anti-explosion dust remover for environment-friendly engineering construction.The anti-explosion dust remover comprises a dust remover box body and an air inlet pipeline communicated with one end of the top of the dust remover box body, a mounting frame is fixedly mounted at the top end in the dust remover box body, and a plurality of evenly-distributed splitter plates are arranged in the mounting frame; and protective shells are fixedly installed on one sides of the multiple splitter plates correspondingly, an adjusting mechanism is arranged at one end of the interior of the mounting frame, a moving mechanism is arranged in the mounting frame, and scraping mechanisms are arranged in the multiple protective shells correspondingly. The dust collector has the beneficial effects that after dust generated by environmental protection engineering construction enters the dust collector box body, airflow entering the dust collector box body can be shunted through a plurality of shunting plates, so that a filter cartridge positioned below an air inlet pipeline is prevented from bearing front impact of high-speed and high-concentration dust particles for a long time.

Description

Technical Field

[0001] This invention relates to the field of dust removal equipment technology, specifically to an explosion-proof dust collector for environmental engineering construction. Background Technology

[0002] In environmental protection engineering construction, dust collectors are the core equipment for dust pollution control. They need to be scientifically selected (such as bag filters, electrostatic precipitators, etc.) based on the engineering conditions (such as flue gas volume, dust characteristics, emission requirements), and through precise installation and commissioning, ensure that they are efficiently integrated with the overall engineering treatment process to achieve dust emission standards.

[0003] A cartridge dust collector is a dust collector that uses cartridges as filtration elements and employs pulse-jet cleaning for reverse cleaning. During operation, dust-laden airflow enters the dust collector housing at high speed through the inlet. The cartridges below the inlet are subjected to the direct impact of high-velocity, high-concentration dust particles, resulting in a significantly higher processing load on some sections of the cartridges below the inlet compared to other locations. Under prolonged operation, compared to cartridges in other positions, the cartridges below the inlet experience faster and thicker dust buildup due to the continuous exposure to high-concentration dust, making them more susceptible to damage. During pulse cleaning, thicker dust layers require greater energy to be thoroughly removed. If the cleaning capacity is insufficient, the remaining dust layer will clump together, affecting subsequent dust collection operations. Summary of the Invention

[0004] The purpose of this invention is to provide an explosion-proof dust collector for environmental engineering construction, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an explosion-proof dust collector for environmental engineering construction, comprising a dust collector housing and an air inlet duct connected to one end of the top of the dust collector housing. An installation frame is fixedly installed at the top of the dust collector housing, and the installation frame is positioned directly below the air inlet duct. Multiple evenly distributed diversion plates are arranged inside the installation frame. A protective shell is fixedly installed on one side of each of the diversion plates. A connecting shaft is fixedly installed inside each of the diversion plates. A movable shell is arranged inside each of the protective shells. Both ends of the connecting shafts are rotatably connected to the installation frame. An adjustment mechanism is provided at one end inside the installation frame. A movable mechanism is provided within the installation frame. A scraping mechanism is provided inside each of the protective shells.

[0006] Preferably, the dust collector housing has multiple evenly distributed filter cartridges fixedly installed inside, a pulse jet cleaning system fixedly installed on one side of the dust collector housing, and a dust discharge pipe and an air outlet pipe connected to the bottom of the dust collector housing, with a dust discharge valve installed inside the dust discharge pipe.

[0007] Preferably, a spark arrester is fixedly installed at the top of the dust collector housing near the air inlet duct, and the outlet of the spark arrester is connected to the air inlet duct.

[0008] Preferably, the adjustment mechanism includes a cylinder and multiple transmission gears. The cylinder is fixedly installed at one end inside the mounting frame. The multiple transmission gears are respectively fixedly sleeved on the outside of one end of multiple connecting shafts. A rack is fixedly installed at the telescopic shaft end of the cylinder. The rack meshes with the multiple transmission gears. Guide rods are slidably sleeved at both ends of the rack. Both guide rods are fixedly installed inside the mounting frame.

[0009] Preferably, the moving mechanism includes a second cylinder, which is fixedly installed on one side of the mounting frame. A moving frame is fixedly installed on the output shaft end of the second cylinder. A guide rod is slidably sleeved on the end of the moving frame away from the second cylinder. The guide rod is fixedly connected to the mounting frame. A transmission shaft is fixedly installed on the end of the moving frame near the adjustment mechanism. A transmission rod is rotatably installed on the bottom of two adjacent moving shells. A transmission frame is rotatably installed on the bottom of the two moving shells at both ends. A groove is opened on the side of the two transmission frames away from the multiple moving shells. The two transmission shafts are respectively located inside the two grooves.

[0010] Preferably, the scraping mechanism includes two scraping plates and two connecting components. The two scraping plates are symmetrically arranged inside the movable shell. Two symmetrically arranged guide rods are fixedly installed on the side of each scraping plate that is away from each other. A connecting plate is fixedly installed on the side of each pair of adjacent guide rods that is away from the corresponding scraping plate. All four guide rods are slidably connected to the corresponding movable shell. Multiple evenly distributed springs are fixedly installed between the side of each connecting plate that is away from each other and the inner wall of the corresponding movable shell. A positioning hole is opened at the same end of each of the two connecting plates.

[0011] Preferably, the connecting assembly includes a positioning rod, a flipping rod, an unlocking rod, and a wedge block. The positioning rod, flipping rod, and unlocking rod are all located at the same end inside the movable shell. The positioning rod cooperates with a corresponding positioning hole. The positioning rod and the unlocking rod are slidably installed at one end inside the movable shell. A spring is fixedly installed between the side of the positioning rod away from the connecting plate and the inner wall of the movable shell. The flipping rod is rotatably connected to the movable shell. The two ends of the flipping rod are slidably connected to the positioning rod and the unlocking rod, respectively. The wedge block is fixedly installed at the top of the corresponding protective shell. The wedge block cooperates with the connecting plate.

[0012] Preferably, both ends of the flipping rod are fixedly installed with sliding rods, and the positioning rod and the unlocking rod are provided with sliding grooves at the ends near the sliding rods, with the two sliding rods respectively set inside the two sliding grooves.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] 1. After the dust generated during environmental engineering construction enters the dust collector housing, multiple diversion plates can divert the airflow into the dust collector housing, allowing the airflow to act on the filter cartridges on both sides. This prevents the filter cartridge located below the air inlet duct from being subjected to the direct impact of high-speed, high-concentration dust particles for a long time. It also prevents the dust layer on its surface from accumulating faster and thicker, extending the service life of the filter cartridge below the air inlet duct and ensuring the dust removal effect of the pulse jet cleaning system on the filter cartridge, thus not affecting subsequent dust removal work.

[0015] 2. The scraping mechanism, in conjunction with the moving mechanism, can clean the surfaces of multiple diverter plates, preventing dust from accumulating on the surfaces of the diverter plates during long-term operation and affecting the diversion effect. At the same time, during the return stroke of the scraping mechanism after cleaning the diverter plate surfaces, the scraping blades of the scraping mechanism no longer contact the diverter plate surfaces, thus preventing the uncleaned dust from being pushed into the corresponding protective housing, and avoiding the accumulation of dust inside the protective housing that would prevent the moving housing from being able to retract inside. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0017] Figure 2 This is a schematic diagram of one side of the dust collector housing of the present invention;

[0018] Figure 3 This is a partial structural diagram of the present invention;

[0019] Figure 4 This is a schematic diagram of the adjustment mechanism structure of the present invention;

[0020] Figure 5 This is a schematic diagram of the bottom structure of the mounting frame of the present invention;

[0021] Figure 6 This is a schematic diagram of the mobile frame structure of the present invention;

[0022] Figure 7 This is a schematic diagram of the multiple movable shell structures of the present invention;

[0023] Figure 8 This is a schematic diagram of the flow divider structure of the present invention;

[0024] Figure 9 For the present invention Figure 8 Enlarged view of point A in the image;

[0025] Figure 10 This is an internal view of the movable shell of the present invention;

[0026] Figure 11 This is a partial view of the interior of the movable shell of the present invention.

[0027] The components represented by each number in the attached diagram are listed below: 1. Dust collector housing; 2. Filter cartridge; 3. Pulse jet cleaning system; 4. Ash discharge pipe; 5. Air inlet duct; 6. Spark catcher; 7. Mounting frame; 8. Diverter plate; 9. Connecting shaft; 10. Protective shell; 11. Moving shell; 12. Cylinder 1; 13. Transmission gear; 14. Guide rod 1; 15. Cylinder 2; 16. Moving frame; 17. Guide rod 2; 18. Transmission shaft; 19. Transmission rod; 20. Transmission frame; 21. Groove; 22. Scraper plate; 23. Air outlet duct; 24. Guide rod 3; 25. Connecting plate; 26. Spring 1; 27. Positioning hole; 28. Positioning rod; 29. ​​Spring 2; 30. Tilting rod; 31. Unlocking rod; 32. Wedge block; 33. Sliding rod; 34. Slide groove; 35. Rack. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] This invention provides a technical solution: such as Figure 1 - Figure 11 The explosion-proof dust collector for environmental engineering construction shown includes a dust collector housing 1 and an air inlet duct 5 connected to the top of the dust collector housing 1. An installation frame 7 is fixedly installed at the top of the dust collector housing 1 and is located directly below the air inlet duct 5. Multiple evenly distributed diversion plates 8 are arranged inside the installation frame 7. A protective shell 10 is fixedly installed on one side of each diversion plate 8. A connecting shaft 9 is fixedly installed inside each diversion plate 8. A movable shell 11 is arranged inside each of the multiple protective shells 10. Both ends of the multiple connecting shafts 9 are rotatably connected to the installation frame 7. An adjustment mechanism is arranged at one end inside the installation frame 7. A movable mechanism is arranged in the installation frame 7. A scraping mechanism is arranged inside each of the multiple protective shells 10.

[0030] Multiple evenly distributed filter cartridges 2 are fixedly installed inside the dust collector housing 1. A pulse jet cleaning system 3 is fixedly installed on one side of the dust collector housing 1. The bottom of the dust collector housing 1 is connected to the ash discharge pipe 4 and the air outlet pipe 23, and the ash discharge pipe 4 is equipped with an ash discharge valve.

[0031] A spark catcher 6 is fixedly installed at the top of the dust collector housing 1 near the air inlet duct 5, and the air outlet of the spark catcher 6 is connected to the air inlet duct 5.

[0032] The adjustment mechanism includes a cylinder 12 and multiple transmission gears 13. The cylinder 12 is fixedly installed inside one end of the mounting frame 7. The multiple transmission gears 13 are respectively fixedly sleeved on the outside of one end of multiple connecting shafts 9. A rack 35 is fixedly installed on the telescopic shaft end of the cylinder 12. The rack 35 meshes with the multiple transmission gears 13. Guide rods 14 are slidably sleeved on both ends of the rack 35. Both guide rods 14 are fixedly installed inside the mounting frame 7.

[0033] The moving mechanism includes a second cylinder 15, which is fixedly installed on one side of the mounting frame 7. A moving frame 16 is fixedly installed on the output shaft end of the second cylinder 15. A guide rod 17 is slidably sleeved on the end of the moving frame 16 away from the second cylinder 15. The guide rod 17 is fixedly connected to the mounting frame 7. A transmission shaft 18 is fixedly installed on the end of the moving frame 16 near the adjustment mechanism. A transmission rod 19 is rotatably installed on the bottom of two adjacent moving shells 11. A transmission frame 20 is rotatably installed on the bottom of the two moving shells 11 at both ends. A groove 21 is opened on the side of the two transmission frames 20 away from the multiple moving shells 11. The two transmission shafts 18 are respectively located inside the two grooves 21.

[0034] The scraping mechanism includes two scraping plates 22 and two connecting components. The two scraping plates 22 are symmetrically arranged inside the movable shell 11. Two symmetrically arranged guide rods 24 are fixedly installed on the side of each scraping plate 22 that is away from each other. A connecting plate 25 is fixedly installed on the side of each pair of adjacent guide rods 24 that is away from the corresponding scraping plate 22. All four guide rods 24 are slidably connected to the corresponding movable shell 11. Multiple evenly distributed springs 26 are fixedly installed between the side of each connecting plate 25 that is away from each other and the inner wall of the corresponding movable shell 11. A positioning hole 27 is opened at the same end of each connecting plate 25.

[0035] The connecting assembly includes a positioning rod 28, a flipping rod 30, an unlocking rod 31, and a wedge block 32. The positioning rod 28, the flipping rod 30, and the unlocking rod 31 are all located at the same end inside the movable shell 11. The positioning rod 28 cooperates with the corresponding positioning hole 27. The positioning rod 28 and the unlocking rod 31 are slidably installed at one end inside the movable shell 11. A spring 29 is fixedly installed between the side of the positioning rod 28 away from the connecting plate 25 and the inner wall of the movable shell 11. The flipping rod 30 is rotatably connected to the movable shell 11. The two ends of the flipping rod 30 are slidably connected to the positioning rod 28 and the unlocking rod 31, respectively. The wedge block 32 is fixedly installed on the top of the corresponding protective shell 10. The wedge block 32 cooperates with the connecting plate 25.

[0036] Both ends of the flipping rod 30 are fixedly installed with slide rods 33. The positioning rod 28 and the unlocking rod 31 are both provided with slide grooves 34 at the ends near the slide rods 33. The two slide rods 33 are respectively set inside the two slide grooves 34.

[0037] Working Principle: During use, dust generated during environmental engineering construction first passes through the spark arrester 6, then enters the air inlet duct 5, and finally enters the dust collector housing 1. The spark arrester 6 effectively captures and extinguishes sparks and high-temperature particles from combustion processes (such as boilers, biomass combustion, and welding), fundamentally eliminating a significant ignition source and greatly reducing the risk of combustion or explosion inside the dust collector housing 1. The explosion-proof principle of the spark arrester 6 is based on eliminating the ignition source required for an explosion through a closed-loop process of "interception-cooling-extinguishing": First, utilizing the inertial difference between sparks and airflow, through structures such as labyrinth baffles and metal filters, high-temperature sparks (800-1500℃) generated by upstream processes are forcibly separated and intercepted from the dust-laden airflow, preventing them from entering the dust collector filter bags and other high-temperature components. The dust concentration area is then used to quickly absorb the heat of the sparks by relying on the high thermal conductivity of the metal material or cooling media such as spray water, so that the temperature drops below the ignition temperature of the combustible dust. Finally, by extending the residence time of the sparks in the collector, collecting the intercepted sparks in the isolation area and cleaning them regularly, the sparks are ensured to be completely extinguished and not reignited, thereby cutting off the three elements of explosion of "combustible dust + oxygen + ignition source" and preventing the risk of dust collector explosion from the root. The dust entering the dust collector housing 1 is filtered by multiple filter cartridges 2 and then enters the interior of multiple filter cartridges 2. Finally, it is discharged through the exhaust pipe 23. After the dust removal work is completed, the dust attached to the surface of multiple filter cartridges 2 is cleaned by the pulse jet system 3. Finally, the ash discharge valve inside the ash discharge pipe 4 is opened to discharge the dust and impurities inside the dust collector housing 1.

[0038] By using multiple diversion plates 8 and adjusting their positions via an adjustment mechanism, the airflow entering the dust collector housing 1 can be diverted, allowing the airflow to act on the filter cartridges 2 on both sides. This prevents the filter cartridges 2 located below the inlet duct 5 from being subjected to the direct impact of high-speed, high-concentration dust particles for extended periods, and also prevents the dust layer on their surface from accumulating faster and thicker, extending the service life of the filter cartridges 2 below the inlet duct 5. This ensures the dust removal effect of the pulse jet system 3 on the filter cartridges 2, thus not affecting subsequent dust removal work. The movement process of the adjustment mechanism is as follows: starting cylinder 12, pushing rack 35 to move stably along two guide rods 14. Since multiple transmission gears 13 mesh with rack 35, multiple transmission gears 13 rotate, driving their respective connecting shafts 9 to rotate, which in turn drives multiple diversion plates 8 to rotate. The angle of the multiple diversion plates 8 tilts, thereby adjusting the flow direction of the airflow entering the dust collector housing 1.

[0039] Multiple flow dividers 8 guide airflow through their surface shapes. However, over time, dust from the airflow can accumulate on the surfaces of these multiple flow dividers 8, interfering with airflow and affecting the flow divider effect. At this point, cylinder 2 15 is activated, causing the moving frame 16 to slide along guide rod 2 17. The two drive shafts 18 move synchronously. Since the two drive shafts 18 are located inside the two grooves 21, they also drive the two drive frames 20 to rotate synchronously as the drive shafts 18 move. The bottoms of the multiple moving shells 11 are connected by drive rods 19, so the multiple moving shells 11 move synchronously as the moving frame 16 moves. The scraping mechanisms inside the multiple moving shells 11 clean the surfaces of the multiple flow dividers 8 to prevent dust from accumulating on the surfaces of the multiple flow dividers 8 during long-term operation, thus affecting the flow divider effect.

[0040] When multiple movable shells 11 move to the end of the mounting frame 7 away from multiple protective shells 10, multiple scraping mechanisms operate synchronously. The movement process of the connecting component in one of the scraping mechanisms is as follows: the unlocking rod 31 touches the mounting frame 7, and the unlocking rod 31 moves inward into the movable shell 11 under force. The unlocking rod 31 acts on the flipping rod 30, and the sliding rods 33 at both ends of the flipping rod 30 slide under the action of their respective corresponding sliding grooves 34. The end of the flipping rod 30 away from the unlocking rod 31 acts on the positioning rod 28, and the positioning rod 28 moves, disengages from the positioning hole 27, and squeezes the second spring 29. The movement process of the other connecting component in the scraping mechanism is the same as above. At this time, both connecting plates 25 are released from fixation. Under the action of their respective corresponding springs 26, the two connecting plates 25 drive the corresponding guide rods 24 and... The scraping plates 22 move synchronously; the scraping plates 22 in the other multiple scraping mechanisms are all away from their respective diverter plates 8. During the resetting process of the multiple moving shells 11, the multiple scraping plates 22 will not push the uncleaned dust into the corresponding protective shell 10. When the multiple scraping plates 22 enter the corresponding protective shell 10, the multiple wedge blocks 32 cooperate with their respective corresponding connecting plates 25, and the multiple scraping plates 22 are moved under force, so that the positioning holes 27 at one end of the multiple connecting plates 25 correspond to the corresponding positioning rods 28. Under the action of their respective corresponding springs 29, the multiple positioning rods 28 are re-engaged into the corresponding positioning holes 27, realizing the re-fixation of the multiple scraping plates 22. The multiple scraping plates 22 are re-attached to their respective corresponding diverter plates 8, so as to be used for the next cleaning of dust on the surface of the diverter plate 8.

[0041] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An explosion-proof dust collector for environmental engineering construction, comprising a dust collector housing (1) and an air inlet duct (5) connected to one end of the top of the dust collector housing (1), characterized in that: An installation frame (7) is fixedly installed at the top of the dust collector housing (1). The installation frame (7) is located directly below the air inlet duct (5). The installation frame (7) has multiple evenly distributed diversion plates (8) inside. A protective shell (10) is fixedly installed on one side of each of the multiple diversion plates (8). A connecting shaft (9) is fixedly installed inside each of the multiple diversion plates (8). A movable shell (11) is provided inside each of the multiple protective shells (10). Both ends of the multiple connecting shafts (9) are rotatably connected to the installation frame (7). An adjustment mechanism is provided at one end inside the installation frame (7). A movable mechanism is provided in the installation frame (7). A scraping mechanism is provided inside each of the multiple protective shells (10).

2. The explosion-proof dust collector for environmental engineering construction according to claim 1, characterized in that: The dust collector housing (1) has multiple uniformly distributed filter cartridges (2) fixedly installed inside. A pulse jet cleaning system (3) is fixedly installed on one side of the dust collector housing (1). The bottom of the dust collector housing (1) is connected to a ash discharge pipe (4) and an air outlet pipe (23), and an ash discharge valve is installed inside the ash discharge pipe (4).

3. The explosion-proof dust collector for environmental engineering construction according to claim 1, characterized in that: A spark catcher (6) is fixedly installed at the top of the dust collector housing (1) near the air inlet pipe (5), and the air outlet of the spark catcher (6) is connected to the air inlet pipe (5).

4. The explosion-proof dust collector for environmental engineering construction according to claim 1, characterized in that: The adjustment mechanism includes a cylinder (12) and multiple transmission gears (13). The cylinder (12) is fixedly installed at one end inside the mounting frame (7). The multiple transmission gears (13) are respectively fixedly sleeved on the outside of one end of multiple connecting shafts (9). A rack (35) is fixedly installed at the telescopic shaft end of the cylinder (12). The rack (35) meshes with the multiple transmission gears (13). Guide rods (14) are slidably sleeved at both ends of the rack (35). Both guide rods (14) are fixedly installed inside the mounting frame (7).

5. The explosion-proof dust collector for environmental engineering construction according to claim 1, characterized in that: The moving mechanism includes a second cylinder (15), which is fixedly installed on one side of the mounting frame (7). A moving frame (16) is fixedly installed on the output shaft end of the second cylinder (15). A guide rod (17) is slidably sleeved on the end of the moving frame (16) away from the second cylinder (15). The guide rod (17) is fixedly connected to the mounting frame (7). A transmission shaft (18) is fixedly installed on the end of the moving frame (16) near the adjustment mechanism. A transmission rod (19) is rotatably installed on the bottom of two adjacent moving shells (11). A transmission frame (20) is rotatably installed on the bottom of the two moving shells (11) at both ends. A groove (21) is opened on the side of the two transmission frames (20) away from the multiple moving shells (11). The two transmission shafts (18) are respectively located inside the two grooves (21).

6. The explosion-proof dust collector for environmental engineering construction according to claim 1, characterized in that: The scraping mechanism includes two scraping plates (22) and two connecting components. The two scraping plates (22) are symmetrically arranged inside the movable shell (11). Two symmetrically arranged guide rods (24) are fixedly installed on the side of the two scraping plates (22) that are far away from each other. A connecting plate (25) is fixedly installed on the side of the two adjacent guide rods (24) that are far away from the corresponding scraping plate (22). All four guide rods (24) are slidably connected to the corresponding movable shell (11). Multiple evenly distributed springs (26) are fixedly installed between the side of the two connecting plates (25) that are far away from each other and the inner wall of the corresponding movable shell (11). A positioning hole (27) is opened on the same end of the two connecting plates (25).

7. The explosion-proof dust collector for environmental engineering construction according to claim 6, characterized in that: The connecting assembly includes a positioning rod (28), a flipping rod (30), an unlocking rod (31), and a wedge block (32). The positioning rod (28), the flipping rod (30), and the unlocking rod (31) are all located at the same end inside the movable shell (11). The positioning rod (28) cooperates with the corresponding positioning hole (27). The positioning rod (28) and the unlocking rod (31) are slidably installed at one end inside the movable shell (11). A spring (29) is fixedly installed between the side of the positioning rod (28) away from the connecting plate (25) and the inner wall of the movable shell (11). The flipping rod (30) is rotatably connected to the movable shell (11). The two ends of the flipping rod (30) are slidably connected to the positioning rod (28) and the unlocking rod (31), respectively. The wedge block (32) is fixedly installed at the top of the corresponding protective shell (10). The wedge block (32) cooperates with the connecting plate (25).

8. The explosion-proof dust collector for environmental engineering construction according to claim 7, characterized in that: Both ends of the flipping rod (30) are fixedly installed with slide rods (33). The positioning rod (28) and the unlocking rod (31) are provided with a slide groove (34) at the end near the slide rod (33). The two slide rods (33) are respectively set inside the two slide grooves (34).

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