Leak-proof star-shaped feeder

Abstract

The utility model provides a leakproof star-shaped feeder, and relates to the technical field of material conveying, the leakproof star-shaped feeder comprises: a housing, the upper part of which is provided with a feed inlet and the lower part of which is provided with a discharge outlet; the rotating shaft is transversely arranged in the shell, and the end part of the rotating shaft is connected with the shell through a bearing; the blades are located between the feeding port and the discharging port, one ends of the blades make sealing contact with the inner wall of the shell, the other ends of the blades are in transmission connection with the rotating shaft, and the multiple blades are arranged in the circumferential direction of the rotating shaft at intervals; the first sealing structure is arranged between the rotating shaft and the shell and is positioned between the bearing and the blade; the second sealing structure is arranged between the rotating shaft and the shell and located between the first sealing structure and the blade; a closed cavity is formed between the first sealing structure and the second sealing structure; and the pressure measuring instrument is communicated with the closed cavity. Compared with the prior art that maintenance measures are taken after the accident occurs, the leakage risk can be detected and found in advance, and the accident of harmful gas leakage can be avoided by adopting preventive maintenance measures.

Description

Technical Field

[0001] This utility model relates to the field of material conveying technology, and in particular to a leak-proof star feeder. Background Technology

[0002] The rotary feeder mainly consists of an impeller, a housing, a reducer, and a motor. Its working principle is that material falls and fills the gaps between adjacent blades of the impeller; then, as the blades rotate, the material is discharged.

[0003] When using a star feeder in the polysilicon production process, the gas inside the polysilicon production equipment is toxic, thus imposing strict requirements on the star feeder for leak-free operation and high airtightness.

[0004] However, despite the sealing measures taken by existing rotary feeders, there is still a risk of leakage in actual use. Moreover, once a leakage occurs, it can often only be dealt with after the fact, which is a delay and poses a potential hazard to the production process. Utility Model Content

[0005] In view of the above situation, this utility model provides a leak-proof rotary feeder, which aims to solve the technical problem that although existing rotary feeders have adopted sealing measures, there is still a risk of leakage in actual use, and once leakage occurs, it can often only be dealt with after the fact, which is a delay and brings potential hidden dangers to the production process.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] This utility model provides a leak-proof rotary feeder, comprising:

[0008] The shell has a feed inlet at the top and a discharge outlet at the bottom;

[0009] The rotating shaft is horizontally arranged inside the housing, and the end of the rotating shaft is connected to the housing through a bearing;

[0010] The blades are located between the inlet and outlet. One end of the blade is in sealed contact with the inner wall of the housing, and the other end is connected to the rotating shaft for transmission. Multiple blades are arranged at intervals along the circumference of the rotating shaft.

[0011] The first sealing structure is disposed between the shaft and the housing, and between the bearing and the blade;

[0012] The second sealing structure is disposed between the rotating shaft and the housing, and between the first sealing structure and the blade; a sealed cavity is formed between the first sealing structure and the second sealing structure;

[0013] The pressure measuring instrument is connected to the sealed cavity.

[0014] In some embodiments of this utility model, the second sealing structure includes a second sealing ring.

[0015] In some embodiments of this utility model, the second sealing structure further includes a positioning sleeve, which has a central hole along its axial direction. One end of the positioning sleeve has a storage groove with a diameter larger than that of the central hole. The central hole is connected to the storage groove. The positioning sleeve is fitted onto the rotating shaft through the central hole, and the second sealing ring is disposed in the storage groove.

[0016] In some embodiments of this utility model, a plurality of second sealing rings are arranged at intervals along the axial direction of the positioning sleeve and adjacent second sealing rings are separated by retaining rings.

[0017] In some embodiments of this utility model, a third sealing structure is also included, which is disposed between the rotating shaft and the housing, and located between the second sealing structure and the blade.

[0018] In some embodiments of this utility model, the third sealing structure includes a third sealing ring; one side of the third sealing ring has a second opening with a V-shaped cross-section, one end of the second opening is narrowed and the other end is open.

[0019] In some embodiments of this utility model, the outer wall of the third sealing ring has outwardly extending wings; the third sealing structure also includes a pressure ring, which is connected to the housing, and one end of the pressure ring has an annular protrusion. The end face of the annular protrusion is used to press the wings of the third sealing ring tightly onto the end of the positioning sleeve, and the third sealing ring is disposed between the annular protrusion and the rotating shaft.

[0020] In some embodiments of this utility model, it further includes:

[0021] Fixed plate, fastened inside the housing;

[0022] The moving plate is arc-shaped, with its inner side in sliding and sealing contact with the end of at least one blade, and its outer side connected to the fixed plate through an elastic component.

[0023] There are two moving plates, which are symmetrically arranged on opposite sides of the rotating shaft. A first gap is left between the upper ends of the two moving plates, and a second gap is left between the lower ends. The first gap is aligned and connected to the feed port, and the second gap is aligned and connected to the discharge port.

[0024] In some embodiments of this utility model, it further includes:

[0025] An axial channel is arranged inside the pressure ring along the axial direction; a blocking plate is provided inside the axial channel.

[0026] A radial channel is arranged radially within the pressure ring. One end of the radial channel is connected to the axial channel, and the other end extends to the outer wall of the pressure ring. The radial channel is filled with hydraulic oil.

[0027] A guide rod with a piston mounted on it, the piston being in sliding seal engagement with the axial channel; one end of the radial channel is located between the piston and the plug plate; the guide rod sliding seal penetrates the plug plate.

[0028] An elastic strip is provided at one end of the guide rod, and the end of the elastic strip slides in contact with the inner wall of the second opening;

[0029] A spring is used to move the elastic strip toward the end where the second opening narrows;

[0030] The movable column has one end in contact with the inner side of the moving plate and the other end extending into the pressure ring and slidingly sealing with the radial channel.

[0031] In some embodiments of this utility model, it also includes an annular movable side plate, which is sleeved on the rotating shaft. One side of the movable side plate is connected to the pressure ring through a telescopic structure. There is a gap between the movable side plate and the side of the blade. One side of the movable side plate faces the moving plate and has an inclined surface. The inner side of the moving plate has a wedge block, one side of which is inclined and slides in contact with the inclined surface.

[0032] The embodiments of this utility model have at least the following advantages or beneficial effects:

[0033] Compared to taking maintenance measures after an accident occurs, this embodiment can detect leakage risks in advance and adopt preventive maintenance measures to avoid accidents involving the leakage of harmful gases.

[0034] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the leak-proof star feeder provided in Example 1;

[0037] Figure 2 for Figure 1 Top view;

[0038] Figure 3 for Figure 1 Sectional view along direction AA;

[0039] Figure 4 for Figure 3A sectional view along the BB direction;

[0040] Figure 5 for Figure 3 A magnified view of the area at position C in the middle;

[0041] Figure 6 This is an exploded view of the second and third sealing structures.

[0042] Figure 7 This is a schematic diagram of the leak-proof star feeder provided in Example 2;

[0043] Figure 8 for Figure 7 A magnified view of the area at position D in the middle;

[0044] Figure 9 This is a schematic diagram of the elastic strip provided in Example 3;

[0045] Figure 10 for Figure 9 A magnified view of the area at position E in the middle;

[0046] Figure 11 for Figure 10 A magnified view of the middle F position;

[0047] Figure 12 for Figure 9 A magnified view of the area at position G.

[0048] icon:

[0049] 1-Shell, 11-Inlet, 12-Outlet

[0050] 2-Shaft, 21-Bearing

[0051] 3-blade, 31-mounting sleeve,

[0052] 41 - First sealing ring,

[0053] 51-Second sealing ring, 511-First opening, 52-Positioning sleeve, 521-Center hole, 522-Placement slot, 53-Retaining ring,

[0054] 6-Sealed cavity,

[0055] 71-Pressure measuring interface, 72-Pressure measuring instrument

[0056] 81-Third sealing ring, 811-Second opening, 812-Wing, 82-Pressure ring, 821-Annular protrusion

[0057] 91-Fixed plate, 92-Moving plate, 921-Wedge block, 93-Arc-shaped spring piece, 94-Axial channel, 941-Blocking plate, 95-Radial channel, 96-Guide rod, 961-Piston, 97-Elastic strip, 98-Moving column, 99-Moving side plate, 991-Inclined surface. Detailed Implementation

[0058] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the present invention.

[0059] In the description of the embodiments of this utility model, it should be understood that the terms "upper", "lower", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this utility model.

[0060] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0061] In this embodiment of the invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment of the invention according to the specific circumstances.

[0062] The embodiments of this utility model will be described in detail below.

[0063] Example 1

[0064] See Figures 1-6 This embodiment provides a leak-proof star feeder, including a housing 1, a rotating shaft 2, blades 3, a first sealing structure, a second sealing structure, a pressure measuring interface 71, and a pressure measuring instrument 72.

[0065] The upper part of the housing 1 has a feed inlet 11 and the lower part has a discharge outlet 12. The feed inlet 11 is used to connect to a material conveying pipeline, and the discharge outlet 12 is used to connect to polysilicon production equipment.

[0066] The rotating shaft 2 is arranged horizontally inside the housing 1, and the end of the rotating shaft 2 is connected to the housing 1 through the bearing 21.

[0067] The blade 3 is located between the inlet 11 and the outlet 12. One end of the blade 3 is in sealed contact with the inner wall of the housing 1, and the other end is connected to the mounting sleeve 31. Multiple blades 3 are arranged at intervals along the circumference of the mounting sleeve 31. The mounting sleeve 31 is fitted on the rotating shaft 2 and the two are driven by a key.

[0068] The first sealing structure is disposed between the rotating shaft 2 and the housing 1, and is located between the bearing 21 and the blade 3.

[0069] The second sealing structure is disposed between the rotating shaft 2 and the housing 1, and is located between the first sealing structure and the blade 3; a sealed cavity 6 is formed between the first sealing structure and the second sealing structure.

[0070] The pressure testing interface 71 is installed on the housing 1 and can be connected to the sealed cavity 6.

[0071] The pressure measuring instrument 72 is connected to the pressure measuring interface 71.

[0072] The working principle of the leak-proof star feeder is as follows: When the rotating shaft 2 rotates at a constant speed, the material entering the housing 1 from the feed inlet 11 falls and fills the space between two adjacent blades 3. As the rotating shaft 2 and the blades 3 rotate, the material is discharged from the discharge outlet 12. The first and second sealing structures create a multi-stage seal between the rotating shaft 2 and the housing 1, reducing the probability of harmful gas leakage. Furthermore, they facilitate the formation of a sealed cavity 6 between the first and second sealing structures. A pressure measuring instrument 72 is used to detect pressure changes in the sealed cavity 6 to predict leakage risk. Specifically, when the second sealing structure fails, harmful gas enters the sealed cavity 6 from between the rotating shaft 2 and the housing 1, causing the pressure in the sealed cavity 6 to rise. The pressure data detected by the pressure measuring instrument 72 increases, indicating an impending leak (because the first sealing structure operates better than the second sealing structure, its lifespan is longer; often, the first sealing structure is still functioning even when the second sealing structure fails, and leakage only occurs when both the first and second sealing structures fail). Therefore, the second sealing structure needs to be replaced promptly. In other words, compared to taking maintenance measures after an accident occurs, this embodiment can detect leakage risks in advance and adopt preventive maintenance measures to avoid accidents involving the leakage of harmful gases.

[0073] The first sealing structure includes a first sealing ring 41 in an annular shape, and the second sealing structure includes a second sealing ring 51 in an annular shape. The inner side of the second sealing ring 51 is in direct or indirect contact with the rotating shaft 2, and the outer side is in direct or indirect contact with the housing 1, thereby achieving a seal.

[0074] The first sealing ring 41 and the second sealing ring 51 have the same shape. One side of the second sealing ring 51 has a first opening 511 with a cross-section that is approximately V-shaped. One end of the first opening 511 is narrowed, and the other end is open and curved inward. By adjusting the size of the open end of the first opening 511, the preload of the second sealing ring 51 during assembly can be adjusted, which helps to improve the airtightness of the first sealing ring 41.

[0075] To facilitate the positioning of the second sealing ring 51, the second sealing structure also includes a positioning sleeve 52. The positioning sleeve 52 has a central hole 521 along its axial direction, and one end of the positioning sleeve 52 has a storage groove 522. The diameter of the storage groove 522 is larger than the diameter of the central hole 521, and the central hole 521 communicates with the storage groove 522. The positioning sleeve 52 is fitted onto the rotating shaft 2 through the central hole 521. The second sealing ring 51 is disposed in the storage groove 522 of the positioning sleeve 52. Multiple second sealing rings 51 are arranged at intervals along the axial direction of the positioning sleeve 52, and adjacent second sealing rings 51 are separated by retaining rings 53. After the positioning sleeve 52 is fitted onto the rotating shaft 2, the storage groove 522 is blocked by the housing 1, and the second sealing ring 51 is confined within the storage groove 522.

[0076] Understandably, sealing measures should also be taken between the outer side of the positioning sleeve 52 and the housing 1.

[0077] The leak-proof star feeder also includes a third sealing structure, which is located between the rotating shaft 2 and the housing 1, and between the second sealing structure and the blade 3. As can be seen from the foregoing, the first sealing structure, the second sealing structure, and the third sealing structure are arranged sequentially and at intervals along the axial direction of the rotating shaft 2, and the multi-stage sealing improves the airtightness.

[0078] The third sealing structure includes a ring-shaped third sealing ring 81. The inner side of the ring-shaped third sealing ring 81 is in direct or indirect contact with the rotating shaft 2, and the outer side is in direct or indirect contact with the housing 1, thereby achieving a seal.

[0079] The third sealing ring 81 has a second opening 811 on one side with a generally V-shaped cross-section. One end of the second opening 811 is narrowed, and the other end is open and curved inward. The outer wall of the third sealing ring 81 has outwardly extending wings 812. By adjusting the size of the open end of the second opening 811, the preload of the third sealing ring 81 during assembly can be adjusted, which helps to improve the airtightness of the third sealing ring 81.

[0080] To facilitate the positioning of the third sealing ring 81, the third sealing structure also includes a pressure ring 82. The pressure ring 82 is connected to the housing 1. One end of the pressure ring 82 has an annular protrusion 821. The end face of the annular protrusion 821 is used to press the wing 812 of the third sealing ring 81 tightly onto the end of the positioning sleeve 52. The third sealing ring 81 is disposed between the annular protrusion 821 and the rotating shaft 2, thereby realizing the positioning of the third sealing ring 81.

[0081] Understandably, sealing measures should also be taken between the pressure ring 82 and the housing 1.

[0082] In other embodiments, the first sealing structure, the second sealing structure, and the third sealing structure may include sealing packing.

[0083] Example 2

[0084] This embodiment is a further improvement based on Embodiment 1.

[0085] See Figures 1-8 The leak-proof star feeder also includes a fixed plate 91 and a moving plate 92. The fixed plate 91 is fastened inside the housing 1. The moving plate 92 is arc-shaped. The inner side of the moving plate 92 is in sliding sealing contact with the end of at least one blade 3, and the outer side is connected to the fixed plate 91 through an elastic component. There are two moving plates 92, which are symmetrically arranged on opposite sides of the rotating shaft 2. A first gap is left between the upper ends of the two moving plates 92, and a second gap is left between the lower ends. The first gap is aligned and connected with the feed port 11, and the second gap is aligned and connected with the discharge port 12.

[0086] The end of blade 3 is easily worn. With the above solution, after the end of blade 3 is worn, the restoring force of the elastic component pushes the moving plate 92 to keep the moving plate 92 in contact with the end of blade 3, thereby ensuring good airtightness between blade 3 and moving plate 92 and preventing harmful gases from entering the feed inlet 11.

[0087] The elastic component includes an arc-shaped spring sheet 93, the two ends of which are slidably connected to the fixed plate 91 (achieved through the cooperation of structures such as sliders and grooves), and the middle part is arched and fastened to the outside of the moving plate 92.

[0088] Example 3

[0089] This embodiment is a further improvement based on embodiment 2.

[0090] See Figures 1-12 The leak-proof star feeder also includes an axial channel 94, a radial channel 95, a guide rod 96, a spring, an elastic strip 97, and a movable column 98.

[0091] The axial channel 94 is arranged along the axial direction of the pressure ring 82 within the pressure ring 82; a blocking plate 941 is provided within the axial channel 94.

[0092] A radial channel 95 is arranged radially within the pressure ring 82. One end of the radial channel 95 communicates with the axial channel 94, and the other end extends to the outer wall of the pressure ring 82. The radial channel 95 is filled with hydraulic oil.

[0093] A piston 961 is provided on the guide rod 96, and the piston 961 is in sliding sealing fit with the axial channel 94; one end of the radial channel 95 is located between the piston 961 and the plug plate 941; the guide rod 96 slides through the plug plate 941.

[0094] An elastic strip 97 is disposed at one end of the guide rod 96, and the end of the elastic strip 97 slides in contact with the inner wall of the second opening 811.

[0095] One end of the spring is connected to the guide rod 96 and the other end is connected to the axial channel 94. The spring is used to move the elastic bar 97 toward the narrowing end of the second opening 811.

[0096] One end of the movable column 98 contacts the inner side of the movable plate 92, and the other end extends into the pressure ring 82 and slides and seals with the radial channel 95.

[0097] When the elastic component pushes the moving plate 92 towards the blade 3, the moving plate 92 drives the movable column 98, which in turn compresses the hydraulic oil. The hydraulic oil pushes the piston 961 and the guide rod 96, which in turn moves the elastic strip 97 towards the narrowing end of the second opening 811. Since the inner wall of the second opening 811 is inclined, the elastic strip 97 tends to expand the second opening 811 as it moves towards the narrowing end, increasing the contact pressure between the third sealing ring 81 and the annular protrusion 821 of the rotating shaft 2 and the pressure ring 82. This slight movement of the moving plate 92 improves the sealing performance of the third sealing ring 81. The force of the arc-shaped spring piece 93 of the elastic component deforms the elastic strip 97, allowing it to bend without obstructing the normal movement of the moving plate 92.

[0098] Example 4

[0099] This embodiment is a further improvement based on embodiment 3.

[0100] See Figures 1-12The leak-proof star feeder also includes an annular movable side plate 99, which is sleeved on the rotating shaft 2. One side of the movable side plate 99 is connected to the pressure ring 82 via a telescopic structure. There is a small gap between the movable side plate 99 and the side of the blade 3. One side of the movable side plate 99 faces the moving plate 92 and has an inclined surface 991. The inner side of the moving plate 92 has a wedge block 921, one side of which is inclined and slides in contact with the inclined surface 991 of the movable side plate 99. In this way, when the moving plate 92 moves to compensate for the wear at the end of the blade 3, the moving plate 92 can push the movable side plate 99 through the wedge block 921, causing the movable side plate 99 to move towards the side of the blade 3, so as to slightly reduce the gap between the movable side plate 99 and the side of the blade 3. This prevents the material from entering the gap and being ground down to a smaller size before entering between the pressure ring 82 and the rotating shaft 2, thus eliminating the potential risk of material leakage.

[0101] Finally, it should be noted that the above are merely preferred embodiments of this application and are not intended to limit this application. For those skilled in the art, this application can have various modifications and variations. Without conflict, the embodiments and features described in the embodiments of this application can be arbitrarily combined with each other. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A leak-proof rotary feeder, characterized in that, include: The shell has a feed inlet at the top and a discharge outlet at the bottom; A rotating shaft is arranged laterally inside the housing, and the end of the rotating shaft is connected to the housing via a bearing; The blade is located between the feed inlet and the discharge outlet. One end of the blade is in sealed contact with the inner wall of the housing, and the other end is connected to the rotating shaft for transmission. Multiple blades are arranged at intervals along the circumference of the rotating shaft. The first sealing structure is disposed between the rotating shaft and the housing, and located between the bearing and the blade; The second sealing structure is disposed between the rotating shaft and the housing, and between the first sealing structure and the blade; a sealed cavity is formed between the first sealing structure and the second sealing structure; The pressure measuring instrument is connected to the sealed cavity.

2. The leak-proof rotary feeder according to claim 1, characterized in that, The second sealing structure includes a second sealing ring.

3. The leak-proof rotary feeder according to claim 2, characterized in that, The second sealing structure further includes a positioning sleeve, which has a central hole along its axial direction. One end of the positioning sleeve has a storage groove with a diameter larger than that of the central hole. The central hole is connected to the storage groove. The positioning sleeve is fitted onto the rotating shaft through the central hole, and the second sealing ring is disposed in the storage groove.

4. The leak-proof rotary feeder according to claim 3, characterized in that, Multiple second sealing rings are arranged at axial intervals along the positioning sleeve and adjacent second sealing rings are separated by retaining rings.

5. The leak-proof rotary feeder according to claim 3, characterized in that, It also includes a third sealing structure, which is disposed between the rotating shaft and the housing, and located between the second sealing structure and the blade.

6. The leak-proof rotary feeder according to claim 5, characterized in that, The third sealing structure includes a third sealing ring; one side of the third sealing ring has a second opening with a V-shaped cross-section, the second opening being narrowed at one end and open at the other end.

7. The leak-proof rotary feeder according to claim 6, characterized in that, The outer wall of the third sealing ring has outwardly extending wings; the third sealing structure also includes a pressure ring, which is connected to the housing. One end of the pressure ring has an annular protrusion, and the end face of the annular protrusion is used to press the wings of the third sealing ring tightly onto the end of the positioning sleeve. The third sealing ring is disposed between the annular protrusion and the rotating shaft.

8. The leak-proof rotary feeder according to claim 7, characterized in that, Also includes: A fixed plate is fastened inside the housing. An arc-shaped movable plate has its inner side in sliding and sealing contact with the end of at least one of the blades, and its outer side connected to the fixed plate via an elastic component. There are two moving plates, which are symmetrically arranged on opposite sides of the rotating shaft. A first gap is left between the upper ends of the two moving plates, and a second gap is left between their lower ends. The first gap is aligned and connected to the feed port, and the second gap is aligned and connected to the discharge port.

9. The leak-proof rotary feeder according to claim 8, characterized in that, Also includes: An axial channel is arranged within the pressure ring along the axial direction of the pressure ring; A blocking plate is provided inside the axial channel; A radial channel is arranged radially within the pressure ring, with one end communicating with the axial channel and the other end extending to the outer wall of the pressure ring; the radial channel is filled with hydraulic oil. A guide rod is provided with a piston, which is in sliding seal engagement with the axial channel; one end of the radial channel is located between the piston and the plug plate; the guide rod slides through the plug plate in a sealing manner. An elastic strip is provided at one end of the guide rod, and the end of the elastic strip slides in contact with the inner wall of the second opening; A spring is used to move the elastic strip toward the end where the second opening narrows; The movable column has one end in contact with the inner side of the movable plate and the other end extending into the pressure ring and slidingly sealing with the radial channel.

10. The leak-proof rotary feeder according to claim 8 or 9, characterized in that, It also includes a ring-shaped movable side plate, which is sleeved on the rotating shaft. One side of the movable side plate is connected to the pressure ring through a telescopic structure. There is a gap between the movable side plate and the side of the blade. One side of the movable side plate faces the moving plate and has an inclined surface. The inner side of the moving plate has a wedge-shaped block, one side of which is inclined and slides in contact with the inclined surface.

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