Plastic bearing barrel

Abstract

The invention discloses a plastic bearing bucket in the technical field of plastic bearing buckets, which comprises a bucket body and a receding bin arranged at the top of the bucket body and capable of communicating with the bucket body; the injection opening is located in the top of the barrel body and is coaxial with the receding bin, and the inner wall of the top of the injection opening can be in threaded connection with a sealing cover; the partition plate is arranged between the receding bin and the injection opening in a sealed mode and elastically slides relative to the receding bin through an elastic telescopic piece. The partition plate can divide the receding bin into a receding cavity communicating with the outside and a fusion cavity fused with the barrel body. The limiting frame is fixedly arranged between the barrel body and the injection opening and used for limiting the lower limit of movement of the partition plate; and the exhaust groove is formed in the top of the receding bin and used for air intake and exhaust of the receding cavity, the partition plate ascends and descends in the additionally-arranged receding bin, the size of the fusion cavity is adjusted, the variable of the storage space caused by deformation of the barrel body is balanced, and the situation that the sealing effect of the sealing cover is affected due to internal pressure increase caused by compression deformation of the barrel body is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of plastic carrying barrels, in particular to a plastic carrying barrel. Background Art

[0002] Plastic load-bearing barrels are widely used in the chemical industry because of their corrosion resistance and low cost; they are often used for the storage and transportation of materials.

[0003] In order to reduce the water hammer effect and leakage during the transfer process, the load-bearing barrel is usually filled with relatively full materials, and then the barrel body is sealed through the threaded cover body and the sealing tape. However, the load-bearing barrel will encounter many inevitable deformations during the transfer process, such as deformation caused by lifting, deformation caused by collision between barrels during transportation, etc.; in order to avoid gas leakage caused by material volatilization and liquid leakage, the volume difference in the barrel cavity caused by deformation can usually only be compensated by compressing a small amount of air in the cavity. When the deformation is large, the air pressure will increase sharply and break through the sealing tape to cause leakage. This is also the fundamental reason why droplets often appear around the lid of the plastic barrel; that is, reducing the water hammer effect and preventing transfer leakage are mutually constrained in the application of plastic barrels and are difficult to solve. Summary of the invention

[0004] The technical problem of the present invention is to provide a plastic carrying barrel, which can be raised and lowered in an additional clearance bin by a partition plate to adjust the size of the fusion cavity, balance the variables of the storage space caused by the deformation of the barrel body, and avoid the increase of internal pressure caused by the compression deformation of the barrel body, which affects the sealing effect of the sealing cover.

[0005] To achieve the above object, the present invention provides the following technical solution: a plastic carrying barrel, comprising a barrel body, and further comprising: The yielding bin is arranged on the top of the barrel and can be communicated with the barrel; A nozzle is located at the top of the barrel and is coaxially arranged with the relief bin, and the inner wall of the top of the nozzle can be threadedly connected to a sealing cover; A partition plate is sealed and arranged between the clearance chamber and the nozzle, and is elastically slidably arranged with the clearance chamber through an elastic telescopic member; the partition plate can divide the clearance chamber into a clearance cavity communicated with the outside and a fusion cavity fused with the barrel body; The limit frame is fixed between the barrel and the pouring port and is used to limit the lower limit of the partition plate; The exhaust groove is opened on the top of the concession chamber and is used for the intake and exhaust of the concession chamber.

[0006] As a further solution of the present invention, the outer wall of the injection nozzle is provided with a clamp, and a fastening cover with a trumpet-shaped cross-section is fixed on the top of the partition plate. The outer wall of the injection nozzle is provided with a lever arm for rotation through a connecting piece, and the lever arm is arranged in a circular array, and the two ends are respectively in contact with the outer wall of the clamp and the inner wall of the fastening cover.

[0007] As a further solution of the present invention, the clamp includes arc-shaped clamps arranged in a circular array, the number of the arc-shaped clamps is in multiple relation with the number of lever arms, each of the arc-shaped clamps is fixed with a pin at one end and a slot at the other end; the arc-shaped clamps are slidably arranged with adjacent arc-shaped clamps through the pins and the slots.

[0008] As a further solution of the present invention, the elastic telescopic parts are distributed in a circular array above the partition plate and are radially slidably arranged along the clearance bin. A synchronization structure is arranged between the fastening cover and the elastic telescopic parts. The synchronization structure can adjust the distance between the elastic telescopic parts and the edge of the partition plate according to the lifting distance of the partition plate.

[0009] As a further solution of the present invention, the synchronization structure includes: The driven hood has an "eight"-shaped cross section and rises and falls synchronously with the partition plate; Synchronous grooves are provided on the side wall of the driven cover and are arranged in a circular array; The synchronous bracket is fixedly arranged at the fixed end of the elastic telescopic member, and a synchronous sheet is fixedly arranged at the end thereof, and the synchronous sheet is fitted to both sides of the inner and outer sides of the driven cover.

[0010] As a further solution of the present invention, the elastic telescopic member comprises: A sliding sleeve and a movable column, wherein the sliding sleeve and the movable column are slidably arranged, and a return spring is arranged between the sliding sleeve and the movable column; The slide rails are arranged in pairs and are respectively fixed on the top of the partition plate and the bottom of the clearance bin; The sliders are arranged in pairs and are respectively fixed to the sliding sleeve and the movable column. The sliders are all slidably arranged in the sliding rails.

[0011] As a further solution of the present invention, an adjustment plate is slidably arranged in the sliding sleeve, the adjustment plate is fixed to the top of the reset spring, the adjustment plate is threadedly connected to an adjustment bolt, and the top of the adjustment bolt is rotatably arranged with the slider and passes through the slider.

[0012] As a further solution of the present invention, the lever arm includes a power arm and a resistance arm, the power arm and the resistance arm are fixed to each other, and the intersection of the power arm and the resistance arm is the hinge point of the lever arm; the power arm and the resistance arm are respectively in contact with the fastening cover and the clamp, and the length of the power arm is greater than the length of the resistance arm.

[0013] Compared with the prior art, the present invention has the following beneficial effects: In the present invention, the makeshift bin is divided into a makeshift chamber and a fusion chamber by a partition plate; when the internal space of the barrel body is reduced due to deformation, the pressure below the partition plate is greater than the pressure above the partition plate, causing the partition plate to rise and the volume of the fusion chamber to increase, compensating for the reduction in storage space caused by the deformation of the barrel body, so that the internal pressure of the barrel body is relieved, avoiding the seal of the sealing cover from being damaged, and improving the sealing effect and sealing pressure resistance of the plastic load-bearing barrel; at the same time, the temperature difference occurring during the long-term storage of the liquid can also be adjusted by moving the partition plate up and down, adjusting the actual use volume in the barrel body, balancing the variables of thermal expansion and contraction of the liquid and air, and reducing the impact on the sealing of the plastic load-bearing barrel; the partition plate only compensates for the actual volume of the barrel body when the barrel body is excessively deformed, thereby avoiding leakage of harmful gases inside the barrel body and avoiding the aggravation of the water hammer effect caused by the increase in space.

[0014] In the present invention, the fastening cover is driven to rise and contact with the lever arm through the partition plate, so that the inner end of the lever arm squeezes the clamp, and the clamp is tightened to fit the nozzle and the sealing cover tightly, thereby improving the sealing effect between the sealing cover and the nozzle; and the more serious the deformation of the barrel body is, the tighter the fit between the sealing cover and the nozzle is, and the better the sealing effect of the plastic load-bearing barrel is; conversely, the clamp loosens the nozzle, and the sealing cover and the nozzle maintain a normal sealing effect, reducing the high-strength extrusion between the sealing cover and the nozzle, avoiding irreversible deformation of the sealing cover and the nozzle, affecting the sealing effect, and at the same time facilitating the disassembly of the sealing cover, reducing the difficulty of using the plastic load-bearing barrel. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0016] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a schematic diagram of the overall cross-sectional structure of the present invention; Figure 3 For the present invention Figure 2 The enlarged structural diagram at A in the middle; Figure 4 It is a schematic diagram of the principle structure of the present invention; Figure 5 This is an exploded structural diagram of the nozzle and its connection relationship of the present invention; Figure 6 For the present invention Figure 5 The enlarged structural diagram at B in the middle; Figure 7 It is a schematic cross-sectional structure diagram of the elastic telescopic member and its connection relationship of the present invention; Figure 8For the present invention Figure 5 The enlarged structural diagram at C in the middle; Fig. 9 This is a schematic diagram of the clamp structure of the present invention; In the accompanying drawings, the components represented by the reference numerals are listed as follows: 1. Barrel body; 2. Make way bin; 21. Make way cavity; 22. Partition plate; 23. Exhaust groove; 3. Injection port; 31. Sealing cover; 32. Limiting frame; 4. Hoop; 41. Arc splint; 42. Latch; 43. Slot; 5. Fastening cover; 51. Connecting piece; 52. Lever arm; 521. Power arm; 522. Resistance arm; 6. Elastic telescopic piece; 61. Sliding sleeve; 62. Movable column; 63. Reset spring; 64. Slide rail; 65. Slider; 71. Adjustment plate; 72. Adjustment bolt; 8. Synchronous structure; 81. Driven cover; 82. Synchronous groove; 83. Synchronous bracket; 84. Synchronous plate. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] See also Figure 1-9 The present invention provides a technical solution: a plastic carrying barrel, comprising a barrel body 1, and further comprising: The yielding chamber 2 is arranged on the top of the barrel body 1 and can be communicated with the barrel body 1; The nozzle 3 is located at the top of the barrel body 1 and is coaxially arranged with the clearance bin 2. The inner wall of the top of the nozzle 3 can be threadedly connected to the sealing cover 31; The partition plate 22 is sealed and arranged between the clearance chamber 2 and the nozzle 3, and is elastically slidably arranged with the clearance chamber 2 through the elastic telescopic member 6; the partition plate 22 can divide the clearance chamber 2 into a clearance cavity 21 communicating with the outside and a fusion cavity fused with the barrel body 1; The limiting frame 32 is fixed between the barrel body 1 and the nozzle 3 and is used to limit the lower limit of the partition plate 22; The exhaust groove 23 is provided at the top of the clearance chamber 2 and is used for the intake and exhaust of the clearance chamber 21; For details, see Figure 2-Figure 4 , inject the liquid into the barrel body 1 through the injection port 3, and tighten the sealing cover 31 on the injection port 3 to isolate the liquid in the barrel body 1 from the outside; The partition plate 22 divides the clearance bin 2 into a clearance chamber 21 and a fusion chamber; when the internal space of the barrel body 1 is reduced due to deformation, the pressure inside the barrel body 1 and the fusion chamber increases; when the pressure of the gas on the partition plate 22 increases to exceed the pre-tightening force applied to the partition plate 22 by the elastic telescopic member 6, the partition plate 22 rises, and the volume of the fusion chamber increases, compensating for the shrinkage of the storage space caused by the deformation of the barrel body 1, so that the internal pressure of the barrel body 1 is relieved, and the seal of the sealing cover 31 is prevented from being damaged, thereby improving the sealing effect and sealing pressure resistance of the plastic load-bearing barrel, and when the barrel body 1 is restored, the partition plate 22 can be reset under the action of the elastic telescopic member 6, so that the preset volume of the barrel body 1 remains stable; At the same time, the temperature difference that occurs during the long-term storage of the liquid can also be adjusted by moving the partition plate 22 up and down, thereby adjusting the size of the fusion chamber, increasing the actual usable volume of the carrying barrel, balancing the variables of thermal expansion and contraction of the liquid and air, and reducing the impact on the sealing of the plastic carrying barrel.

[0019] Since the present invention can compensate for the temporary volume change of the barrel body by driving the partition plate 22 to move by pressure, it can avoid material leakage caused by deformation of the barrel body 1. Secondly, since the partition plate 22 can be reset, that is, the partition plate 22 only compensates the actual volume of the barrel body 1 when the barrel body 1 is excessively deformed, it can avoid the leakage of harmful gases inside the barrel body and the aggravation of the water hammer effect caused by the increase in space.

[0020] The reasons for the leakage of plastic barrels during transportation also include: the sealing cover 31 is usually not absolutely tightened. This is because, on the one hand, absolute tightening will make the process of disassembling and assembling the sealing cover 31 more difficult, and on the other hand, maintaining absolute tightening for a long time will cause fatigue damage to the nozzle 3.

[0021] As a further solution of the present invention, the outer wall of the nozzle 3 is sleeved with a clamp 4, the top of the partition plate 22 is fixed with a fastening cover 5 with a trumpet-shaped cross section, and the outer wall of the nozzle 3 is rotatably provided with a lever arm 52 through a connecting piece 51, and the lever arm 52 is arranged in a circular array, and the two ends are respectively in contact with the outer wall of the clamp 4 and the inner wall of the fastening cover 5; For details, see Figure 2 and Figure 3 When the partition plate 22 rises, the fastening cover 5 rises accordingly, and the fastening cover 5 pushes up the end of the lever arm 52 that contacts it, and causes the lever arm 52 to rotate to squeeze the clamp 4, and the clamp 4 is tightened and causes the nozzle 3 to deform to fit tightly on the sealing cover 31, so as to fill the gap between the threads and improve the sealing effect between the sealing cover 31 and the nozzle 3. Moreover, the more serious the deformation of the barrel body 1 is, the tighter the fit between the sealing cover 31 and the nozzle 3 is, and the better the sealing effect of the plastic load-bearing barrel is. On the contrary, when the partition plate 22 is reset downward, the clamp 4 releases the injection port 3, and the sealing cover 31 and the injection port 3 maintain a normal sealing effect, reducing the high-strength extrusion between the sealing cover 31 and the injection port 3, avoiding irreversible deformation of the sealing cover 31 and the injection port 3 that affects the sealing effect, and at the same time facilitating the disassembly of the sealing cover 31 and reducing the difficulty of using the plastic carrying barrel.

[0022] As a further solution of the present invention, the clamp 4 includes arc-shaped clamps 41 arranged in a circular array, the number of the arc-shaped clamps 41 is in multiple relation with the lever arm 52, one end of each arc-shaped clamp 41 is fixed with a latch 42, and the other end is provided with a slot 43; the arc-shaped clamp 41 is slidably arranged with adjacent arc-shaped clamps 41 through the latch 42 and the slot 43; For details, see Fig. 9 When the lever arm 52 squeezes the clamp 4, first, the arc-shaped clamp 41 contacts it, and the pin 42 at the end of the arc-shaped clamp 41 goes deep into the slot 43 of the side wall of the adjacent arc-shaped clamp 41, shortening the gap between the arc-shaped clamps 41, thereby evenly squeezing the injection port 3, making the injection port 3 evenly stressed, and reducing the harmful deformation caused by uneven stress on the injection port 3.

[0023] In order to reduce the difficulty and cost of installation, the partition plate 22 is usually made of plastic material, and the elastic telescopic part 6 is located in the middle of the partition plate 22 to prevent the partition plate 22 from being bent downward when it is pre-tightened; however, this will cause the outer edge of the partition plate 22 to be slightly bent and deformed when the air pressure is high, and the inner edge is small in size and does not deform significantly with increasing pressure, which can be simply compensated by increasing the thickness of the sealing ring.

[0024] As a further solution of the present invention, the elastic telescopic members 6 are distributed in a circular array above the partition plate 22 and are radially slidably arranged along the clearance bin 2. A synchronization structure 8 is arranged between the fastening cover 5 and the elastic telescopic members 6. The synchronization structure 8 can adjust the distance between the elastic telescopic members 6 and the edge of the partition plate 22 according to the lifting distance of the partition plate 22. Specifically, Figure 2 and Figure 3 When the barrel wall of the barrel body 1 is squeezed and deformed, the partition plate 22 rises, the distance between the clearance bin 2 and the partition plate 22 is shortened, the elastic telescopic member 6 accumulates force and shortens in length, and the synchronous structure 8 synchronously pushes the elastic telescopic member 6 to the edge of the partition plate 22 according to the rising distance of the partition plate 22, so as to avoid excessive deformation of the upper edge of the outer wall of the partition plate 22, resulting in a gap between the outer wall of the partition plate 22 and the inner wall of the clearance bin 2, causing the liquid in the load-bearing barrel to flow out, thereby reducing the sealing effect of the load-bearing barrel; after the barrel wall of the barrel body 1 is restored, the elastic telescopic member 6 extends and resets the partition plate 22; By utilizing the elastic telescopic member 6 that moves radially along the partition plate 22 , it is possible to ensure pre-tightening while avoiding the problem of difficulty in sealing the outer edge of the partition plate 22 due to changes in air pressure.

[0025] As a further solution of the present invention, the synchronization structure 8 includes: The driven cover 81 has an "eight"-shaped cross section and rises and falls synchronously with the partition plate 22; The synchronization grooves 82 are provided on the side wall of the driven cover 81 and are arranged in a circular array; The synchronous bracket 83 is fixedly mounted on the fixed end of the elastic telescopic member 6, and a synchronous piece 84 is fixedly mounted on the end thereof, and the synchronous piece 84 is attached to both the inner and outer sides of the driven cover 81; Specifically, Figure 5-Figure 7 The driven cover 81 rises synchronously with the partition plate 22. Since the fixed end of the elastic telescopic member 6 of the synchronous bracket 83 is fixed (that is, fixed to the sliding sleeve 61), an axial displacement of the barrel body 1 occurs between the synchronous bracket 83 and the driven cover 81. The driven cover 81 pushes the elastic telescopic member 6 toward the outside of the partition plate 22 through the synchronous piece 84. Conversely, the driven cover 81 descends and the elastic telescopic member 6 moves toward the inside of the partition plate 22, thereby adjusting the distance between the elastic telescopic member 6 and the edge of the partition plate 22 according to the lifting distance of the partition plate 22.

[0026] As a further solution of the present invention, the elastic telescopic member 6 comprises: A sliding sleeve 61 and a movable column 62, wherein the sliding sleeve 61 and the movable column 62 are slidably arranged, and a return spring 63 is arranged between the sliding sleeve 61 and the movable column 62; The slide rails 64 are arranged in pairs and are fixed to the top of the partition plate 22 and the bottom of the clearance bin 2 respectively; The sliders 65 are arranged in pairs and are fixed to the sliding sleeve 61 and the movable column 62 respectively. The sliders 65 are slidably arranged in the sliding rail 64; For details, see Figure 7 When the partition plate 22 rises, the movable column 62 is driven to rise by the slider 65 and the slide rail 64, and the movable column 62 compresses the return spring 63. The return spring 63 is used to push the movable column 62 to move relative to the sliding sleeve 61 in the opposite direction, so as to realize the extension and retraction of the elastic telescopic member 6; The slide block 65 and the slide rail 64 can realize that the elastic telescopic member 6, the partition plate 22, and the clearance bin 2 are relatively fixed in the axial direction, and can slide in the radial direction relative to each other.

[0027] As a further solution of the present invention, an adjustment plate 71 is slidably disposed in the sliding sleeve 61, the adjustment plate 71 is fixed to the top of the return spring 63, the adjustment plate 71 is threadedly connected to an adjustment bolt 72, the top of the adjustment bolt 72 is rotatably disposed with the slider 65 and penetrates the slider 65; For details, see Figure 7Rotating the adjusting bolt 72 can change the position of the adjusting plate 71 in the sliding sleeve 61, thereby changing the position of the top of the reset spring 63, and pressing the movable column 62 downward through the reset spring 63 to lower the partition plate 22, which can prevent the liquid or gas from expanding due to heat, causing the partition plate 22 to rise and the clamp 4 to clamp, making it more difficult to disassemble the sealing cover 31.

[0028] As a further solution of the present invention, the lever arm 52 includes a power arm 521 and a resistance arm 522, the power arm 521 and the resistance arm 522 are fixed to each other, and the intersection of the power arm 521 and the resistance arm 522 is the hinge point of the lever arm 52; the power arm 521 and the resistance arm 522 respectively contact the fastening cover 5 and the clamp 4, and the length of the power arm 521 is greater than that of the resistance arm 522; it can amplify the force of the fastening cover 5 and increase the sealing effect of the injection port 3 and the sealing cover 31.

Claims

1. A plastic carrying barrel, comprising a barrel body (1), characterized in that: Also includes: The yield chamber (2) is arranged on the top of the barrel body (1) and can be communicated with the barrel body (1); A nozzle (3) is located at the top of the barrel (1) and is coaxially arranged with the relief chamber (2); the inner wall of the top of the nozzle (3) can be threadedly connected to a sealing cover (31); A partition plate (22) is sealingly disposed between the clearance chamber (2) and the nozzle (3), and is elastically slidably disposed with the clearance chamber (2) via an elastic telescopic member (6); the partition plate (22) is capable of dividing the clearance chamber (2) into a clearance cavity (21) communicating with the outside world and a fusion cavity fused with the barrel body (1); A limit frame (32) is fixedly arranged between the barrel body (1) and the pouring port (3) and is used to limit the lower limit of the movement of the partition plate (22); An exhaust groove (23) is provided at the top of the clearance chamber (2) and is used for the intake and exhaust of the clearance chamber (21).

2. A plastic carrying bucket according to claim 1, characterized in that: The outer wall of the nozzle (3) is sleeved with a clamp (4), the top of the partition plate (22) is fixedly provided with a fastening cover (5) with a trumpet-shaped cross section, and the outer wall of the nozzle (3) is rotatably provided with a lever arm (52) through a connecting piece (51), and the lever arm (52) is arranged in a circular array, and the two ends of the lever arm (52) respectively contact the outer wall of the clamp (4) and the inner wall of the fastening cover (5).

3. A plastic carrying bucket according to claim 2, characterized in that: The hoop (4) comprises arc-shaped clamping plates (41) arranged in a circular array, the number of the arc-shaped clamping plates (41) being in multiple relation with the lever arm (52), one end of each arc-shaped clamping plate (41) being fixedly provided with a latch (42) and the other end being provided with a slot (43); the arc-shaped clamping plates (41) are slidably arranged with adjacent arc-shaped clamping plates (41) via the latch (42) and the slot (43).

4. The plastic carrying bucket according to claim 2, characterized in that: The elastic telescopic members (6) are distributed in a circular array above the partition plate (22) and are radially slidably arranged along the clearance bin (2). A synchronization structure (8) is arranged between the fastening cover (5) and the elastic telescopic members (6). The synchronization structure (8) can adjust the distance between the elastic telescopic members (6) and the edge of the partition plate (22) according to the lifting distance of the partition plate (22).

5. The plastic carrying bucket according to claim 4, characterized in that: The synchronization structure (8) comprises: The driven cover (81) has an "eight"-shaped cross section and rises and falls synchronously with the partition plate (22); Synchronous grooves (82) are formed on the side wall of the driven cover (81) and are arranged in a circular array; The synchronous bracket (83) is fixedly mounted on the fixed end of the elastic telescopic member (6), and a synchronous sheet (84) is fixedly mounted on the end thereof. The synchronous sheet (84) is fitted on both inner and outer sides of the driven cover (81).

6. The plastic carrying bucket according to claim 4, characterized in that: The elastic telescopic member (6) comprises: A sliding sleeve (61) and a movable column (62), wherein the sliding sleeve (61) and the movable column (62) are slidably arranged, and a return spring (63) is arranged between the sliding sleeve (61) and the movable column (62); The slide rails (64) are arranged in pairs and are respectively fixed to the top of the partition plate (22) and the bottom of the clearance bin (2); The sliders (65) are arranged in pairs and are respectively fixed to the sliding sleeve (61) and the movable column (62). The sliders (65) are slidably arranged in the sliding rails (64).

7. The plastic carrying bucket according to claim 6, characterized in that: An adjustment plate (71) is slidably disposed in the sliding sleeve (61), the adjustment plate (71) is fixed to the top of the return spring (63), the adjustment plate (71) is threadedly connected to an adjustment bolt (72), and the top of the adjustment bolt (72) is rotatably disposed with the slider (65) and penetrates the slider (65).

8. The plastic carrying bucket according to claim 2, characterized in that: The lever arm (52) comprises a power arm (521) and a resistance arm (522); the power arm (521) and the resistance arm (522) are fixed to each other, and the intersection of the power arm (521) and the resistance arm (522) is a hinge point of the lever arm (52); the power arm (521) and the resistance arm (522) respectively contact the fastening cover (5) and the clamp (4), and the length of the power arm (521) is greater than that of the resistance arm (522).

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