Airtightness rapid detection device for diaphragm production line

Abstract

The application discloses a kind of airtightness rapid detection device for diaphragm production line, it is related to diaphragm airtightness rapid detection technical field.The shell is placed in the shell inside bottom end and is equipped with placing table, the shell inside top is equipped with pressure table by first electric push rod, the pressure table left and right sides are equipped with pressing rod, and the pressing rod bottom is equipped with extrusion block.The present application, by setting the rotating plate, connecting rod and pressure holding rod, can flatten the diaphragm when the pressure table and the placing table are closed, and the wrinkles of the diaphragm can cause local stress concentration, form a small gap or cover the real defects.After flattening, the diaphragm surface is flat, the leakage path of the detection gas is clear, and the misjudgment caused by wrinkles is avoided.The contact surface of the flattened diaphragm and the sealing ring is flat, the pressure distribution is uniform, and the local overpressure caused by the sealing ring wear or plastic deformation can be avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rapid detection of diaphragm air tightness, in particular to a rapid air tightness detection device for diaphragm production line. BACKGROUND

[0002] The diaphragm air tightness detection device is a special equipment for detecting whether various diaphragms (such as filter membranes, diaphragms, sealing membranes, etc.) have leakage and whether the air permeability meets the standard, so as to verify the air tightness performance. It quantitatively or qualitatively judges the sealing integrity of the diaphragm by simulating the pressure, medium and other conditions in the actual working environment of the diaphragm, and is one of the core equipment for controlling the quality in the production and application of diaphragms.

[0003] When detecting the air tightness of the diaphragm, the existing equipment is usually inconvenient to pull the diaphragm to be detected flat, and the wrinkles or bending of the diaphragm can cause local stress concentration, form a small gap or deformation area, the wrinkles can cover the actual existence of a small hole or crack, and the gas can diffuse through the internal channel of the wrinkles, rather than directly detected from the outside, thereby affecting the detection result of the diaphragm, and when detecting the thicker diaphragm, the sealing performance of the sealing ring is not increased synchronously, the thicker diaphragm usually has higher rigidity and resilience, which can cause a small gap between the contact surface of the diaphragm and the sealing ring, at this time, the detection gas can leak through the gap, affecting the detection effect of the diaphragm.

[0004] In view of the above problems, it is urgent to make innovative design on the basis of the original. SUMMARY

[0005] The purpose of the present application is to provide a rapid air tightness detection device for diaphragm production line, so as to solve the problem that the existing equipment is usually inconvenient to pull the diaphragm to be detected flat, and the wrinkles or bending of the diaphragm can cause local stress concentration, and when detecting the thicker diaphragm, the thicker diaphragm usually has higher rigidity and resilience, which can cause a small gap between the contact surface of the diaphragm and the sealing ring, the technical scheme of the present application provides a solution significantly different from the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a rapid airtightness testing device for a diaphragm production line, comprising a housing, a placement platform installed at the bottom of the housing, a pressure platform installed at the top of the housing via a first electric push rod, pressure rods installed on the left and right sides of the pressure platform, a squeezing block installed at the bottom of the pressure rods, a vertically limited sliding plate in the internal cavity of the placement platform, a sealing ring installed at the top of the sliding plate, a sealing adjustment assembly installed inside and on the side of the placement platform, a rotating plate arranged in the internal cavity of the pressure platform, a connecting rod slidably limited in the internal groove of the rotating plate, a holding rod arranged at the end of the connecting rod away from the rotating plate, a groove opened at the bottom of the pressure platform, the holding rod sliding within the groove, and a flattening adjustment mechanism installed at the top of the rotating plate and the top of the connecting rod;

[0007] The flattening adjustment mechanism includes a mounting bracket installed on the top of the connecting rod, a buffer platform that is limited and slidable inside the mounting bracket, and a sliding rod that is limited and slidable in the protrusion at the top of the connecting rod. A sleeve is installed at the top of the rotating plate, and a connecting plate is fitted on the outer surface of the sleeve. A third electric push rod is installed on the top of the connecting plate, and the protruding end of the third electric push rod passes through the connecting plate and is fitted with a pressing block. A fixing rod is installed at the top of the cavity inside the placement platform, and the sleeve is fitted on the surface of the fixing rod.

[0008] Preferably, the number of connecting rods is four sets, and the inside of the rotating plate is provided with four sets of arc-shaped grooves, which are evenly distributed in a circular shape inside the rotating plate. The connecting rods slide within the arc-shaped grooves inside the rotating plate.

[0009] Preferably, the surface of the placement platform has a groove that extends through the internal cavity of the placement platform, the moving plate slides vertically within the groove, and the surface of the extrusion block has an inclined surface.

[0010] Preferably, the buffer platform is composed of two parallel circular plates and a spring perpendicular to the two circular plates. A protruding rod is installed at the upper end of the top circular plate of the buffer platform, and the protruding rod passes through the top of the mounting frame. The bottom end of the bottom circular plate of the buffer platform is connected to the pressure rod, and the bottom of the pressure rod is designed with a semi-circular arc.

[0011] Preferably, a spring is fitted on the surface of the slide rod, and the spring is connected to the top protrusion of the connecting rod. An inclined block is installed at one end of the slide rod near the buffer platform, and the inclined surface of the inclined block abuts against the upper protrusion of the top circular plate of the buffer platform. The end of the protrusion at the other end of the slide rod is designed as a semi-circular arc and abuts against the inclined surface of the holding block.

[0012] Preferably, the sleeve surface is provided with a spiral groove, the bottom boss of the fixing rod slides within the spiral groove of the mounting frame, and a spring is installed at the top of the sleeve, with the other end of the spring connected to the top of the cavity inside the placement platform.

[0013] Preferably, the sealing adjusting assembly comprises a resisting frame installed at the side end of the placing table, a moving frame is installed at the top of the resisting frame close to the side of the placing table, a top block is rotatably connected in the moving frame, a second electric push rod is installed at the left end of the moving frame, an insertion block is installed at the extension end of the second electric push rod, and a resisting block is installed at the bottom of the moving plate.

[0014] Preferably, a spring is installed at the side of the resisting frame close to the placing table, and the other end of the spring is connected with the side end of the placing table, and a convex block is installed at the side of the resisting frame away from the placing table, and the surface of the convex block is in a semicircular arc shape.

[0015] Preferably, a torsion spring is installed between the top block and the moving frame, an inclined slot is formed at the bottom of the top block, the insertion block is in abutment with the inclined slot at the bottom of the top block, and an inclined surface is arranged on the surface of the top block and in abutment with the bottom of the resisting block.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] 1. According to the present application, the film can be flattened when the pressing table and the placing table are closed by arranging the rotating plate, the connecting rod and the pressing rod, the film wrinkles can cause local stress concentration, form a small gap or cover the real defects, after flattening, the film surface is flat, the leakage path of the detected gas is clear, the misjudgment caused by wrinkles is avoided, and the contact surface between the flattened film and the sealing ring is flat, the pressure is uniformly distributed, the local overpressure caused sealing ring wear or plastic deformation can be avoided, and the flattening adjusting mechanism can be established to synchronously adjust the flattening force of the pressing rod according to the thickness of the film, the pressing force of the pressing rod is dynamically adjusted according to the film thickness, the flattening force and the film stiffness and elastic modulus are matched, and the detection error is eliminated from the root.

[0018] 2. According to the present application, the pressure of the sealing ring on the film can be increased when the pressing table and the placing table are closed by arranging the moving plate and the sealing ring, the elastic decline of the sealing ring caused by creep or fatigue after long-term use can be avoided, the permanent deformation of the sealing ring can be automatically compensated by the continuous pressing function of the moving plate, the sealing adjusting assembly can be established to dynamically adjust the pressure of the sealing ring according to the thickness of the film, the problems of insufficient sealing ring pressure, loose sealing, excessive pressure that may injure the thin film and cause the film to be damaged and the detection result to be distorted are avoided, the permanent deformation of the sealing ring can be filled in real time by the pressing and automatic compensation functions of the moving plate, the sealing ring can be tightly attached to the film at all times with the set pressure, and the detection error caused by the sealing gap is eliminated from the source. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a schematic view of the main structure of the present application;

[0020] Figure 2The structure schematic diagram of the placing table and the pressing table of the present application;

[0021] Figure 3 The structure schematic diagram of the placing table and the pressing table of the present application;

[0022] Figure 4 The structure schematic diagram of the placing table and the pressing table of the present application; Figure 3

[0023] Figure 5 The structure schematic diagram of the placing table and the pressing table of the present application;

[0024] Figure 6 The structure schematic diagram of the placing table and the pressing table of the present application; Figure 5

[0025] Figure 7 The structure schematic diagram of the placing table and the pressing table of the present application;

[0026] Figure 8 The structure schematic diagram of the placing table and the pressing table of the present application;

[0027] Figure 9 The structure schematic diagram of the placing table and the pressing table of the present application;

[0028] Figure 10 The structure schematic diagram of the placing table and the pressing table of the present application;

[0029] In the figure: 1, the shell; 2, the placing table; 3, the first electric push rod; 4, the pressing table; 5, the pressing rod; 6, the extrusion block; 7, the moving plate; 8, the sealing ring; 901, the abutting frame; 902, the moving frame; 903, the top block; 904, the second electric push rod; 905, the plug block; 906, the abutting block; 10, the rotating plate; 11, the connecting rod; 12, the pressing rod; 131, the mounting frame; 132, the buffer table; 133, the sliding rod; 134, the sleeve; 135, the connecting plate; 136, the third electric push rod; 137, the pressing block; 138, the fixed rod. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0031] Please refer to Figures 1-10 ​​The application provides a technical scheme: a gas tightness rapid detection device for a diaphragm production line, which comprises a shell 1, a placing table 2 is installed at the bottom of the shell 1, a pressing table 4 is installed at the top of the shell 1 through a first electric push rod 3, pressing rods 5 are installed on the left and right sides of the pressing table 4, extrusion blocks 6 are installed at the bottom of the pressing rods 5, a moving plate 7 is vertically limited and slides in the internal cavity of the placing table 2, a sealing ring 8 is installed at the top of the moving plate 7, a sealing adjusting assembly is installed in the internal cavity of the placing table 2 and at the side end, a rotating plate 10 is arranged in the internal cavity of the pressing table 4, a connecting rod 11 is limited and slides in the sliding groove in the rotating plate 10, a pressing rod 12 is arranged at the end of the connecting rod 11 away from the rotating plate 10, a groove is formed in the bottom of the pressing table 4, the pressing rod 12 is limited and slides in the groove, and a flattening adjusting mechanism is installed at the top of the rotating plate 10 and the top of the connecting rod 11.

[0032] The number of the connecting rods 11 is four groups, four groups of arc-shaped grooves are formed in the rotating plate 10 and are evenly distributed in a circumferential shape in the rotating plate 10, the connecting rods 11 are limited and slide in the arc-shaped grooves in the rotating plate 10, a groove is formed in the surface of the placing table 2 and penetrates the internal cavity of the placing table 2, the moving plate 7 is vertically limited and slides in the groove, and an inclined surface is formed in the surface of the extrusion block 6.

[0033] The diaphragm to be detected is placed on the top of the placing table 2, at this time, the controller drives the extending end of the first electric push rod 3 to drive the pressing table 4 to descend, so that the pressing table 4 is closed with the placing table 2, at this time, the controller sprays gas from the placing table 2 to press the diaphragm, so as to detect the gas tightness of the diaphragm.

[0034] As an embodiment of the application, the flattening adjusting mechanism comprises a mounting frame 131 installed at the top of the connecting rod 11, a buffer table 132 is limited and slides in the mounting frame 131, a sliding rod 133 is limited and slides in the protrusion at the top of the connecting rod 11, a sleeve 134 is installed at the top of the rotating plate 10, a connecting plate 135 is sleeved on the outer surface of the sleeve 134, a third electric push rod 136 is installed at the top of the connecting plate 135, the extending end of the third electric push rod 136 penetrates the connecting plate 135 and is provided with a pressing block 137, a fixed rod 138 is installed at the top of the internal cavity of the placing table 2, and the sleeve 134 is sleeved on the surface of the fixed rod 138;

[0035] The buffer table 132 is composed of two mutually parallel circular plates and springs perpendicular to the two circular plates, a convex rod is installed on the top end of the top circular plate of the buffer table 132, and the convex rod penetrates the top of the mounting frame 131, the bottom end of the bottom circular plate of the buffer table 132 is connected with the pressing rod 12, the bottom of the pressing rod 12 is designed as a semicircular arc, springs are sleeved on the surface of the sliding rod 133, and the springs are connected with the top convex block of the connecting rod 11, a bevel is installed on one end of the sliding rod 133 close to the buffer table 132, the inclined surface of the bevel is in abutment with the top convex rod of the top circular plate of the buffer table 132, the other end of the sliding rod 133 is designed as a semicircular arc, and is in abutment with the inclined surface of the pressing block 137, a spiral groove is formed in the surface of the sleeve 134, the bottom convex block of the fixing rod 138 is limited to slide in the spiral groove of the mounting frame 131, a spring is installed at the top end of the sleeve 134, and the other end of the spring is connected with the top end of the internal cavity of the placing table 2, the establishment of the flattening adjusting mechanism can synchronously adjust the flattening force of the pressing rod 12 according to the thickness of the diaphragm, the pressure of the pressing rod 12 is dynamically adjusted according to the thickness of the diaphragm, the flattening force is matched with the rigidity and elastic modulus of the diaphragm, and detection errors are eliminated from the root;

[0036] When the pressing table 4 and the placing table 2 are about to be closed, the pressing rod 12 is in contact with the diaphragm at this time, the buffer table 132 applies an abutment force to the pressing rod 12, then the pressing table 4 continues to descend, at this time, the pressing rod 12 drives the connecting rod 11 to move upwards, the connecting rod 11 drives the rotating plate 10 to move upwards at the same time, and the third electric push rod 136 drives the rotating plate 10 to rotate in the internal cavity of the placing table 2 at the same time, so that the pressing rod 12 slides in the arc-shaped groove in the rotating plate 10, thereby driving the pressing rod 12 to expand outwardly in the groove at the bottom of the pressing table 4, and the diaphragm is flattened, when a thicker diaphragm is detected, the controller drives the third electric push rod 136 to push the pressing block 137 to move downwards at this time, at this time, the pressing block 137 extrudes the convex block at one end of the sliding rod 133 close to the sleeve 134, so that the sliding rod 133 moves towards the pressing rod 12, thereby causing the bevel at the other end of the sliding rod 133 to extrude the convex rod at the top end of the buffer table 132 to reversely extrude the buffer table 132, so that the pressing force of the buffer table 132 is increased.

[0037] As one of the embodiments of the present application, the sealing adjusting assembly comprises a resisting frame 901 installed at the side end of the placing table 2, a moving frame 902 installed at the top of the resisting frame 901 close to one side of the placing table 2, a top block 903 rotatably connected in the moving frame 902, a second electric push rod 904 installed at the left end of the moving frame 902, an insertion block 905 installed at the extending end of the second electric push rod 904, a resisting block 906 installed at the bottom of the moving plate 7, a spring installed at the side of the resisting frame 901 close to the placing table 2, and the other end of the spring connected with the side end of the placing table 2, a convex block installed at the side of the resisting frame 901 away from the placing table 2, and the surface of the convex block is semicircular. The establishment of the sealing adjusting assembly can dynamically adjust the pressure applied to the sealing ring 8 according to the thickness of the diaphragm, so as to avoid the problems of insufficient pressure of the sealing ring 8, loose sealing, excessive pressure which may injure the thin diaphragm and cause the diaphragm to be damaged, and detection error caused by sealing gap. Through the pressure application and automatic compensation function of the moving plate 7, the permanent deformation of the sealing ring 8 can be filled in real time, so as to ensure that the sealing ring 8 is always tightly attached to the diaphragm with the set pressure, and eliminate the detection error caused by the sealing gap from the source.

[0038] When the pressing table 4 is lowered and the placing table 2 is closed, the pressing rod 5 is driven to move downward, the extrusion block 6 at the bottom end of the pressing rod 5 will gradually contact the convex block at the side of the resisting frame 901 away from the placing table 2, and gradually apply pressure to the convex block. At this time, the resisting frame 901 drives the moving frame 902 to move towards the inside of the placing table 2, and when the moving frame 902 moves, the inclined surface of the top block 903 applies pressure to the resisting block 906 at the bottom of the moving plate 7, so that the resisting block 906 drives the moving plate 7 to move upward. At this time, the moving plate 7 drives the sealing ring 8 to move upward to seal the diaphragm. When a thicker diaphragm is detected, the controller drives the second electric push rod 904 to extend the insertion block 905 to extrude the inclined groove at the bottom of the top block 903, so that the angle of the inclined surface of the top block 903 is increased, thereby increasing the distance of the moving plate 7 driven by the resisting block 906 to move upward, and increasing the pressure applied to the diaphragm by the sealing ring 8.

[0039] Working principle: during detection, first, the diaphragm to be detected is placed on the top of the placing table 2. At this time, the controller drives the first electric push rod 3 to extend the extending end to drive the pressing table 4 to descend, so that the pressing table 4 is closed with the placing table 2. At this time, the controller sprays gas from the placing table 2 to apply pressure to the diaphragm, so as to detect the air tightness of the diaphragm.

[0040] When the pressing table 4 and the placing table 2 are about to be closed, the buffer table 132 exerts a resistance force on the pressing rod 12 at this time, and then the pressing table 4 continues to descend, at which time the pressing rod 12 drives the connecting rod 11 to move upwards, the connecting rod 11 moves upwards while driving the rotating plate 10 to move upwards, and at the same time, the third electric push rod 136 bottom boss limits and slides in the internal spiral groove of the sleeve 134, thereby driving the rotating plate 10 to rotate in the cavity of the placing table 2, so that the pressing rod 12 slides in the internal arc-shaped groove of the rotating plate 10, thereby driving the pressing rod 12 to expand outwardly in the groove at the bottom of the pressing table 4, and the diaphragm is pulled flat, and when a thicker diaphragm is detected, the controller drives the third electric push rod 136 to drive the pressing block 137 to move downwards at this time, at which time the pressing block 137 extrudes the protrusion close to one end of the sleeve 134 of the slide rod 133, so that the slide rod 133 moves towards the pressing rod 12, thereby making the other end of the slide rod 133 extrude the top protrusion of the buffer table 132 to make it reversely extrude the buffer table 132, so as to increase the pressing force of the buffer table 132;

[0041] When the pressing table 4 descends and the placing table 2 is closed, the pressing rod 5 moves downwards, and the bottom extrusion block 6 gradually contacts the protrusion away from the placing table 2 side of the resistance frame 901 and gradually exerts a pressure thereon, at which time the resistance frame 901 drives the moving frame 902 to move towards the inside of the placing table 2, and when the moving frame 902 moves, the inclined surface of the top block 903 exerts a pressure on the resistance block 906 of the moving plate 7 bottom, so that the resistance block 906 drives the moving plate 7 to move upwards, at which time the moving plate 7 drives the sealing ring 8 to move upwards to seal the diaphragm, and when a thicker diaphragm is detected, the controller drives the second electric push rod 904 to drive the plug block 905 to extend and extrude the bottom inclined groove of the top block 903, so as to increase the angle of the inclined surface of the top block 903, thereby increasing the distance of the resistance block 906 driving the moving plate 7 to move upwards, and increasing the pressure of the sealing ring 8 exerted on the diaphragm.

[0042] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can make modifications to the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to part of the technical features, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A kind of air-tightness quick detection device for diaphragm production line, including shell (1), it is characterized by: The inside bottom of the shell (1) is provided with a placing table (2), the inside top of the shell (1) is provided with a pressing table (4) through a first electric push rod (3), the left and right sides of the pressing table (4) are provided with pressing rods (5), the bottom of the pressing rod (5) is provided with an extrusion block (6), the inside cavity of the placing table (2) is vertically limited to slide a moving plate (7), the top of the moving plate (7) is provided with a sealing ring (8), the inside of the placing table (2) is provided with a sealing adjusting assembly, the inside cavity of the pressing table (4) is provided with a rotating plate (10), the inside sliding groove of the rotating plate (10) is limited to slide a connecting rod (11), the end, away from the rotating plate (10), of the connecting rod (11) is provided with a pressing rod (12), the bottom of the pressing table (4) is provided with a groove, the pressing rod (12) is limited to slide in the groove, and the top of the rotating plate (10) and the top of the connecting rod (11) are provided with a flattening adjusting mechanism. The flattening adjusting mechanism comprises a mounting frame (131) mounted on the top of the connecting rod (11), a buffer table (132) limited to slide in the mounting frame (131), and a sliding rod (133) limited to slide in the protrusion on the top of the connecting rod (11), the top of the rotating plate (10) is provided with a sleeve (134), the outer surface of the sleeve (134) is sleeved with a connecting plate (135), the top of the connecting plate (135) is provided with a third electric push rod (136), the third electric push rod (136) penetrates through the connecting plate (135) and is provided with a pressing block (137), the top of the sleeve (134) is provided with a sleeve (134), and the surface of the sleeve (134) is sleeved with a sleeve (134).

2. The air tightness rapid detection device for diaphragm production line according to claim 1, characterized in that: The number of the connecting rod (11) is four groups, four groups of arc-shaped grooves are formed in the inside of the rotating plate (10), and the four groups of arc-shaped grooves are uniformly distributed in a circumferential shape in the inside of the rotating plate (10), and the connecting rod (11) is limited to slide in the arc-shaped groove in the inside of the rotating plate (10).

3. The air tightness rapid detection device for diaphragm production line according to claim 1, characterized in that: The surface of the placing table (2) is provided with a groove, and the groove penetrates the inside cavity of the placing table (2), the moving plate (7) is vertically limited to slide in the groove, and the surface of the extrusion block (6) is provided with an inclined surface.

4. The air tightness rapid detection device for diaphragm production line according to claim 1, characterized in that: The buffer table (132) is composed of two mutually parallel circular plates and a spring perpendicular to the two circular plates, a protruding rod is mounted on the top circular plate of the buffer table (132), and the protruding rod penetrates through the top of the mounting frame (131), the bottom plate of the buffer table (132) is connected with the pressing rod (12), and the bottom of the pressing rod (12) is designed in a semicircular arc.

5. The air tightness rapid detection device for diaphragm production line according to claim 1, characterized in that: The surface of the sliding rod (133) is sleeved with a spring, and the spring is connected with the protrusion on the top of the connecting rod (11), the end, close to the buffer table (132), of the sliding rod (133) is provided with an inclined block, the inclined surface of the inclined block is in abutment with the protruding rod on the top of the top circular plate of the buffer table (132), and the other end of the protruding block of the sliding rod (133) is designed in a semicircular arc and is in abutment with the inclined surface of the pressing block (137).

6. The air tightness rapid detection device for diaphragm production line according to claim 1, characterized in that: The sleeve (134) is provided with a spiral groove, the bottom end of the fixed rod (138) is limited to slide in the spiral groove of the mounting frame (131), the top end of the sleeve (134) is provided with a spring, and the other end of the spring is connected with the top end of the inner cavity of the placing table (2).

7. The air tightness rapid detection device for diaphragm production line according to claim 1, characterized in that: The sealing adjusting assembly comprises a resisting frame (901) mounted on the side end of the placing table (2), a moving frame (902) mounted on the top of the resisting frame (901) and close to one side of the placing table (2), a top block (903) rotatably connected in the moving frame (902), a second electric push rod (904) mounted on the left end of the moving frame (902), and an inserting block (905) mounted on the extending end of the second electric push rod (904), and a resisting block (906) mounted on the bottom of the moving plate (7).

8. The air tightness rapid detection device for diaphragm production line according to claim 7, characterized in that: The resisting frame (901) is provided with a spring mounted on the side of the placing table (2) and connected with the other end of the placing table (2), and a protruding block mounted on the side of the resisting frame (901) away from the placing table (2) and in a semicircular arc shape.

9. The air tightness rapid detection device for a diaphragm production line according to claim 7, characterized in that: A torsion spring is mounted between the top block (903) and the moving frame (902), an inclined groove is formed in the bottom of the top block (903), the inserting block (905) is in abutment with the inclined groove in the bottom of the top block (903), and an inclined surface is arranged on the surface of the top block (903) and in abutment with the bottom of the resisting block (906).

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