A monitoring system for rock burst

Abstract

A monitoring system for rock burst, characterized in that it includes a borehole stress gauge and a borehole stress gauge driving device; when installing the borehole stress gauge in a borehole, one end of the outer sleeve is sleeved on the left end of the left end cover, the socket I is connected to the socket II by an insertion rod, one end of the rotating rod is inserted into the slot, and the outer sleeve and the rotating rod are pushed in the borehole to push the borehole stress gauge to a specified position of the borehole; the rotating rod is rotated, the rotating rod drives the connecting rod to rotate, the connecting rod pushes the push rod to move linearly, the push rod pushes the upper pressure plate to move upward, and makes the upper pressure plate and the lower pressure plate close to the borehole wall and generate a certain pre-pressure, so as to realize the active pressure bearing of the borehole stress gauge; then the rotating rod and the outer sleeve are removed from the borehole. The outer sleeve is connected to the left end cover by the insertion rod, and when the rotating rod is rotated, the operator holds the outer sleeve, which effectively prevents the outer sleeve and the borehole stress gauge from rotating.

Description

Technical Field

[0001] The present invention relates to the technical field of rock burst monitoring, and in particular to a rock burst monitoring system. Background Art

[0002] At present, in the mine, the mining of coal will inevitably cause the redistribution of the rock stress field. The new stress field distribution state has an extremely important impact on the stability of the tunnel and the mining area. Especially for deep mining mines, rock bursts caused by the high concentration of surrounding rock stress field often occur. Rock bursts are a dynamic phenomenon characterized by sudden, rapid and violent destruction of coal and rock masses around mine tunnels and mining areas due to the release of deformation energy. In essence, it is caused by the sudden release of a large amount of elastic energy. The rock burst problem is essentially a stress problem of coal and rock masses. Therefore, for the monitoring of rock bursts, "stress" is the most reliable physical quantity. Therefore, accurately monitoring the changes in surrounding rock stress is of great significance to maintaining the safety of mining areas and tunnel spaces.

[0003] For monitoring of rock burst, it is usually necessary to install a borehole stress gauge in a deep blind borehole of Φ40 to Φ60 with a hole depth of 8-25 meters. Connect various components as required and push the borehole stress gauge into the borehole.

[0004] The prior art has the following technical problems:

[0005] 1. The design principles of existing borehole stress sensors are basically divided into the following two types:

[0006] (1) Using the hydraulic principle through the built-in oil cylinder or oil bag, during installation, the drilling stress sensor is first pushed to the preset drilling depth position through the installation tool, and then the volume of the hydraulic oil chamber is changed through a manual hydraulic pump or tool to ensure that the pressure-bearing surface of the drilling stress sensor is in close contact with the hole wall, thereby achieving the effect of active pressure bearing. When the top plate is under pressure, the pressure plate is displaced under the action of stress, causing the volume of the hydraulic chamber to decrease, thereby increasing the pressure. Under the action of liquid pressure, the local position of the cylinder body with the stress strain gauge is elastically deformed, and the stress value is calculated by the pressure formula. The drilling stress sensor produced by this principle has the problem of poor linearity or inaccurate or ineffective force measurement due to leakage in or out of the hydraulic chamber.

[0007] (2) The non-active pressure-bearing borehole stress sensor is a sensor with a strain gauge directly installed in the hole, and the filling material is used to ensure that the sensor is in full contact with the hole wall. However, the construction is very difficult, and it is easy for the filling to be incomplete or the filling material to be inappropriate, resulting in pressure release. It is also easy to inaccurately measure or fail to measure the actual stress.

[0008] 2. In the prior art, it is very difficult to push the borehole stress gauge into place in the borehole.

[0009] This is the shortcoming of the existing technology. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a monitoring system for rock burst in view of the deficiencies in the prior art. The borehole stress gauge used does not require hydraulic medium, can actively bear pressure, and is convenient to install in the borehole.

[0011] The present invention is realized by the following technical measures: a monitoring system for rock burst, comprising a borehole stress gauge and a borehole stress gauge driving device; the borehole stress gauge comprises an upper pressure plate and a lower pressure plate, the left end of the lower pressure plate is fixedly connected with a left end cover or the lower pressure plate and the left end cover are integrally formed, the right end of the lower pressure plate is fixedly connected with a right end cover or the lower pressure plate and the right end cover are integrally formed, the upper pressure plate is slidably arranged between the left end cover and the right end cover, and a pushable support is arranged between the upper pressure plate and the lower pressure plate A push rod is provided for moving the upper pressure plate up and down, and a stress-sensitive component and a conversion circuit thereof are attached to the lower pressure plate, and the stress-sensitive component and the conversion circuit thereof are connected to a display instrument outside the borehole through a data line, and the stress-sensitive component and the conversion circuit thereof are prior art and will not be described in detail here; a connecting rod for driving the push rod is connected to one end of the push rod, and the connecting rod is arranged through the left end cover, and the connecting rod is threadedly connected to the left end cover, and a slot is arranged at one end of the connecting rod, and a jack I is arranged at one end of the left end cover;

[0012] The drilling stress gauge driving device comprises an outer sleeve, a rotating rod is arranged inside the outer sleeve, the rotating rod is threadedly connected to the outer sleeve, and a socket II matching with the socket I is arranged at one end of the outer sleeve;

[0013] When installing the drilling stress gauge in the borehole, one end of the outer sleeve is sleeved on the left end of the left end cover, the socket I is connected with the socket II by the plug rod, one end of the rotating rod is inserted into the slot, and the outer sleeve and the rotating rod are pushed in the borehole to push the drilling stress gauge to the specified position of the borehole; the rotating rod is rotated, the rotating rod drives the connecting rod to rotate, the connecting rod pushes the push rod to move linearly, the push rod pushes the upper pressure plate to move upward, and makes the upper pressure plate and the lower pressure plate close to the borehole wall and generate a certain pre-pressure, so as to realize the active pressure of the drilling stress gauge; then the rotating rod and the outer sleeve are removed from the borehole. The outer sleeve is connected to the left end cover by the plug rod, and when the rotating rod is rotated, the operator holds the outer sleeve, which effectively prevents the outer sleeve and the drilling stress gauge from rotating.

[0014] Preferably, the lower pressure plate and the left end cover are provided with a wire hole I for placing the data line, and the outer sleeve is provided with a wire hole II for placing the data line. Providing wire hole I and wire hole II facilitates the placement of the data line.

[0015] Preferably, one end of the outer sleeve connected to the drilling stress gauge is a bell mouth, and the maximum outer diameter of the outer sleeve is smaller than the maximum outer diameter of the left end cover.

[0016] Preferably, the outer sleeve can be detachably assembled and connected by a plurality of outer sleeve segments; the rotating rod can be detachably assembled and connected by a plurality of rotating rod segments. The outer sleeve and the rotating rod are both assembled from multiple segments, thus avoiding the problem that the outer sleeve and the rotating rod are too long and difficult to operate, and the outer sleeve can protect the rotating rod inside it.

[0017] Preferably, a plurality of outer sleeve segments are threadedly connected to form the entire outer sleeve, and a plurality of rotating rod segments are threadedly connected to form the entire rotating rod.

[0018] Preferably, one end of the rotating rod and the slot are provided with teeth that cooperate with each other, so that the rotating rod can drive the connecting rod to rotate when inserted into the slot.

[0019] The structure of the borehole stress gauge can be set in the following three forms:

[0020] (i) The push rod includes a push rod body and a spherical protrusion arranged on the push rod body, the upper pressure plate is provided with a groove I that cooperates with the spherical protrusion, the lower pressure plate is provided with a groove II that cooperates with the spherical protrusion, the spherical protrusion is in point contact with the groove I, and the spherical protrusion is in point contact with the groove II.

[0021] When installing the borehole stress sensor in the borehole, the operator inserts the long rod into the slot and then rotates the connecting rod. Since the connecting rod is threadedly connected to the left end cover, the connecting rod can pull the push rod to move back and forth left and right during the rotation process; by pulling the push rod to move linearly back and forth, the push rod can push the upper pressure plate to move up and down along the left end cover and / or the right end cover, and at the same time, the upper and lower pressure plates will be close to the borehole wall and generate a certain pre-pressure to achieve active pressure. The impact ground pressure is transmitted to the lower pressure plate through the upper pressure plate and the spherical protrusion. The pressure-sensitive component and its conversion circuit convert the elastic change of the lower pressure plate and transmit it to the display instrument through the data line, and the change in pressure value is read through the display instrument.

[0022] (ii) The push rod includes a push rod body and a hemispherical protrusion arranged on the push rod body, the upper pressure plate is provided with a groove I that cooperates with the hemispherical protrusion, the hemispherical protrusion is in point contact with the groove I, the lower pressure plate is provided with a groove III that cooperates with the push rod body, and the push rod body is in contact with the inner wall of the groove III.

[0023] (III) The push rod includes a push rod body and a hemispherical protrusion arranged on the push rod body, the lower pressure plate is provided with a groove II that cooperates with the hemispherical protrusion, the hemispherical protrusion and the groove II are in point contact, the upper pressure plate is provided with a groove IV that cooperates with the push rod body, and the push rod body is in contact with the inner wall of the groove IV.

[0024] The second and third structural forms are improvements on the first structural form. The borehole stress gauge is installed in the borehole, and the upper pressure plate is moved upward by pushing the push rod to realize active pressure bearing. On the basis of realizing active pressure bearing, since the push rod body is in contact with the upper pressure plate or the lower pressure plate, the rock burst pressure can be transmitted to the lower pressure plate in a relatively uniform distribution, thereby improving the stability and accuracy of the rock burst pressure monitoring by the stress sensitive components.

[0025] Preferably, a slot is provided on the push rod, and a claw is provided on the connecting rod. The claw can rotate in the slot, and the slot limits the position of the claw in the left-right direction.

[0026] Preferably, the right end of the left end cover is provided with a guide groove I and / or the left end of the right end cover is provided with a guide groove II, and the left end and / or the right end of the upper pressure plate are provided with a guide protrusion, and the upper pressure plate can move up and down along the guide groove I and / or the guide groove II through the guide protrusion.

[0027] Compared with the prior art, the present invention has the following advantages: the rock burst monitoring system is installed in the borehole, and the upper pressure plate is moved upward by pushing the push rod to realize active pressure bearing. On the basis of realizing active pressure bearing, since the push rod body is fitted with the upper pressure plate or the lower pressure plate, the rock burst pressure can be transmitted to the lower pressure plate in a relatively uniform distribution, thereby improving the stability and accuracy of the rock burst monitoring by the stress sensitive components.

[0028] It can be seen that compared with the prior art, the present invention has substantial characteristics and progress, and the beneficial effects of its implementation are also obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description will be briefly introduced below. Obviously, the accompanying drawings in the following description 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.

[0030] Figure 1 It is a structural schematic diagram of the present invention;

[0031] Figure 2 It is a schematic diagram of the installation of the outer sleeve and the rotating rod;

[0032] Figure 3 for Figure 1 Schematic diagram of the structure of the borehole stress gauge;

[0033] Figure 4 Schematic diagram of the structure of the drilling stress gauge Figure 1 ;

[0034] Figure 5 for Figure 4 Structural schematic diagram of the middle and upper pressure plate;

[0035] Figure 6 for Figure 4 Structural schematic diagram of the middle and lower pressure plates;

[0036] Figure 7 for Figure 4 Schematic diagram of the structure of the middle push rod;

[0037] Figure 8 Schematic diagram of the structure of the drilling stress gauge Figure 2 ;

[0038] Fig. 9 for Figure 8 Structural schematic diagram of the middle and lower pressure plates;

[0039] Fig.10 The structure diagram of the left end cover Figure 1 ;

[0040] Fig.11 The structure diagram of the left end cover Figure 2 ;

[0041] Fig.12 It is a structural schematic diagram of the right end cover;

[0042] Fig.13 for Fig. 9 Schematic diagram of the structure of the middle push rod.

[0043] In the figure: 1-upper pressure plate, 1.1-groove I, 1.2-guide protrusion, 2-lower pressure plate, 2.1-groove II, 2.2-wire hole I, 2.3-groove III, 3-left end cover, 3.1-through hole, 3.2-guide groove I, 3.3-jack I, 4-right end cover, 4.1-guide groove II, 5-push rod, 5.1-spherical protrusion, 5.2-card slot, 5.3-hemispherical protrusion, 6-connecting rod, 6.1-slot, 6.2-claw, 7-stress sensitive components and conversion circuits thereof, 8-data line, 9-outer sleeve, 9.1-jack II, 9.2-wire hole II, 10-rotating rod, 11-plug rod. DETAILED DESCRIPTION

[0044] In order to make the purpose, features and advantages of the invention more obvious and easy to understand, the technical solution protected by the invention will be clearly and completely described below using specific embodiments and drawings. Obviously, the embodiments described below are only part of the embodiments of the invention, not all of them. Based on the embodiments in this patent, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this patent.

[0045] As shown in the figure, a rock burst monitoring system includes a borehole stress gauge and a borehole stress gauge driving device; the borehole stress gauge includes an upper pressure plate 1 and a lower pressure plate 2, the left end of the lower pressure plate 2 is fixedly connected to a left end cover 3 or the lower pressure plate 2 and the left end cover 3 are integrally formed, and the right end of the lower pressure plate 2 is fixedly connected to a right end cover 4 or the lower pressure plate 2 and the right end cover are integrally formed, Figure 3 The disclosed drilling stress gauge, wherein the lower pressure plate 2 and the left end cover 3 and the right end cover 4 are integrally formed. Figure 4 and Figure 8 In the drilling stress gauge disclosed in the specification, the left end of the lower pressure plate 2 is fixedly connected to the left end cover 3, and the right end of the lower pressure plate 2 is fixedly connected to the right end cover 4.

[0046] The upper pressure plate 1 is slidably arranged between the left end cover 3 and the right end cover 4, and a push rod 5 is arranged between the upper pressure plate 1 and the lower pressure plate 2 to push the upper pressure plate 1 to move up and down. Stress-sensitive components and their conversion circuits 7 are attached to the lower pressure plate 2. The stress-sensitive components and their conversion circuits 7 are connected to the display instrument outside the borehole through the data line 8. One end of the push rod 5 is connected to a connecting rod 6 for driving the push rod 5, and the connecting rod 6 is arranged through the left end cover 3. The connecting rod 6 is threadedly connected to the left end cover 3, and one end of the connecting rod 6 is provided with a slot 6.1, and one end of the left end cover 3 is provided with a socket I3.3.

[0047] The drilling stress gauge driving device comprises an outer sleeve 9, a rotating rod 10 is arranged inside the outer sleeve, the rotating rod 10 is threadedly connected to the outer sleeve, and one end of the outer sleeve 9 is provided with a socket II 9.1 matched with the socket I 3.3.

[0048] When installing the drilling stress gauge in the borehole, one end of the outer sleeve 9 is sleeved on the left end of the left end cover 3, the socket I3.3 is connected to the socket II9.1 through the plug rod 11, one end of the rotating rod 10 is inserted into the slot 6.1, and the outer sleeve 9 and the rotating rod 10 are pushed in the borehole to push the drilling stress gauge to the specified position of the borehole; the rotating rod 10 is rotated, and the rotating rod 10 drives the connecting rod 6 to rotate, and the connecting rod 6 pushes the push rod 5 to move linearly, and the push rod 5 pushes the upper pressure plate 1 to move upward, and makes the upper pressure plate 1 and the lower pressure plate 2 close to the borehole wall and generate a certain pre-pressure, so as to realize the active pressure bearing of the drilling stress gauge; then the rotating rod 10 and the outer sleeve 9 are removed from the borehole.

[0049] The lower pressure plate 2 and the left end cover 3 are provided with a wire hole Ⅰ2.2 for placing the data wire 8, and the outer sleeve 9 is provided with a wire hole II9.2 for placing the data wire 8.

[0050] One end of the outer sleeve 9 connected to the drilling stress gauge is a bell mouth, and the maximum outer diameter of the outer sleeve 9 is smaller than the maximum outer diameter of the left end cover 3.

[0051] The outer sleeve 9 can be detachably assembled and connected by a plurality of outer sleeve segments; the rotating rod 10 can be detachably assembled and connected by a plurality of rotating rod segments. Further, a plurality of outer sleeve segments are threadedly connected to form the entire outer sleeve 9, and a plurality of rotating rod segments are threadedly connected to form the entire rotating rod 10.

[0052] One end of the rotating rod 10 is provided with teeth that match each other on the slot 6.1, so that the rotating rod 10 inserted into the slot 6.1 can drive the connecting rod 6 to rotate.

[0053] like Figure 4-7 As shown, the push rod 5 includes a push rod body and a spherical protrusion 5.1 arranged on the push rod body, the upper pressure plate 1 is provided with a groove Ⅰ1.1 that cooperates with the spherical protrusion 5.1, and the lower pressure plate 2 is provided with a groove Ⅱ2.1 that cooperates with the spherical protrusion 5.1, the spherical protrusion 5.1 is in point contact with the groove Ⅰ1.1, and the spherical protrusion 5.1 is in point contact with the groove Ⅱ2.1.

[0054] like Figure 8 , 9 As shown in Figure 13, the push rod 5 includes a push rod body and a hemispherical protrusion 5.3 arranged on the push rod body, the upper pressure plate 1 is provided with a groove Ⅰ1.1 which cooperates with the hemispherical protrusion 5.3, and the hemispherical protrusion 5.3 is in point contact with the groove Ⅰ1.1, and the lower pressure plate 2 is provided with a groove Ⅲ2.3 which cooperates with the push rod body, and the push rod body is in contact with the inner wall of the groove Ⅲ2.3.

[0055] In addition, the drilling stress gauge can also be set to the following structure: the push rod 5 includes a push rod body and a hemispherical protrusion 5.3 arranged on the push rod body, the lower pressure plate 2 is provided with a groove II2.1 that cooperates with the hemispherical protrusion 5.3, the hemispherical protrusion 5.3 and the groove II2.1 are in point contact, the upper pressure plate 1 is provided with a groove IV that cooperates with the push rod body, the push rod body is fitted with the inner wall of the groove IV, and the structure of the groove IV is the same as that of the groove III.

[0056] The push rod 5 is provided with a slot 5.2, and the connecting rod 6 is provided with a claw 6.2. The claw 6.2 can rotate in the slot 5.2, and the slot 5.2 limits the position of the claw 6.2 in the left and right directions.

[0057] The right end of the left end cover 3 is provided with a guide groove I3.2 and / or the left end of the right end cover 4 is provided with a guide groove II4.1, and the left end and / or the right end of the upper pressure plate 1 is provided with a guide protrusion 1.2, and the upper pressure plate 1 can move up and down along the guide groove I3.2 and / or the guide groove II4.1 through the guide protrusion 1.2.

[0058] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0059] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel and inventive features disclosed herein.

Claims

1. A rock burst monitoring system, characterized by: It includes a borehole stress gauge and a borehole stress gauge driving device; The borehole stress gauge comprises an upper pressure plate (1) and a lower pressure plate (2); the left end of the lower pressure plate (2) is fixedly connected to a left end cover (3) or the lower pressure plate (2) and the left end cover (3) are integrally formed; the right end of the lower pressure plate (2) is fixedly connected to a right end cover (4) or the lower pressure plate (2) and the right end cover are integrally formed; the upper pressure plate (1) is slidably arranged between the left end cover (3) and the right end cover (4); a push rod (5) is arranged between the upper pressure plate (1) and the lower pressure plate (2) to push the upper pressure plate (1) to move up and down ), a stress-sensitive component and a conversion circuit (7) are attached to the lower pressure plate (2), the stress-sensitive component and the conversion circuit (7) are connected to a display instrument outside the borehole via a data line (8), one end of the push rod (5) is connected to a connecting rod (6) for driving the push rod (5), the connecting rod (6) passes through the left end cover (3), the connecting rod (6) is threadedly connected to the left end cover (3), one end of the connecting rod (6) is provided with a slot (6.1), and one end of the left end cover (3) is provided with a socket I (3.3); The drilling stress gauge driving device comprises an outer sleeve (9), a rotating rod (10) is arranged inside the outer sleeve, the rotating rod (10) is threadedly connected to the outer sleeve, and one end of the outer sleeve (9) is provided with a socket II (9.1) that matches the socket I (3.3); When installing the borehole stress gauge in the borehole, one end of the outer sleeve (9) is sleeved on the left end of the left end cover (3), the socket I (3.3) is connected to the socket II (9.1) by the insertion rod (11), one end of the rotating rod (10) is inserted into the slot (6.1), and the outer sleeve (9) and the rotating rod (10) are pushed in the borehole to push the borehole stress gauge to a specified position of the borehole; the rotating rod (10) is rotated, the rotating rod (10) drives the connecting rod (6) to rotate, the connecting rod (6) pushes the push rod (5) to move linearly, and the push rod (5) pushes the upper pressure plate (1) to move upward, so that the upper pressure plate (1) and the lower pressure plate (2) are closely attached to the borehole wall and generate a certain pre-pressure, so as to realize active pressure bearing of the borehole stress gauge; then the rotating rod (10) and the outer sleeve (9) are removed from the borehole; The push rod (5) comprises a push rod body and a spherical protrusion (5.1) arranged on the push rod body, the upper pressure plate (1) is provided with a groove I (1.1) matching with the spherical protrusion (5.1), the lower pressure plate (2) is provided with a groove II (2.1) matching with the spherical protrusion (5.1), the spherical protrusion (5.1) and the groove I (1.1) are in point contact, and the spherical protrusion (5.1) and the groove II (2.1) are in point contact; Alternatively, the push rod (5) comprises a push rod body and a hemispherical protrusion (5.3) arranged on the push rod body, the upper pressure plate (1) is provided with a groove I (1.1) cooperating with the hemispherical protrusion (5.3), the hemispherical protrusion (5.3) and the groove I (1.1) are in point contact, the lower pressure plate (2) is provided with a groove III (2.3) cooperating with the push rod body, the push rod body is in contact with the inner wall of the groove III (2.3); Alternatively, the push rod (5) comprises a push rod body and a hemispherical protrusion (5.3) arranged on the push rod body, the lower pressure plate (2) is provided with a groove II (2.1) cooperating with the hemispherical protrusion (5.3), the hemispherical protrusion (5.3) and the groove II (2.1) are in point contact, and the upper pressure plate (1) is provided with a groove IV cooperating with the push rod body, and the push rod body is in contact with the inner wall of the groove IV.

2. The rock burst monitoring system according to claim 1, characterized in that: The lower pressure plate (2) and the left end cover (3) are provided with a wire hole I (2.2) for accommodating the data line (8), and the outer sleeve (9) is provided with a wire hole II (9.2) for accommodating the data line (8).

3. The rock burst monitoring system according to claim 1 or 2, characterized in that: One end of the outer sleeve (9) connected to the borehole stress gauge is a bell mouth, and the maximum outer diameter of the outer sleeve (9) is smaller than the maximum outer diameter of the left end cover (3).

4. The rock burst monitoring system according to claim 1 or 2, characterized in that: The outer sleeve (9) is detachably assembled and connected by a plurality of outer sleeve segments; and the rotating rod (10) is detachably assembled and connected by a plurality of rotating rod segments.

5. The rock burst monitoring system according to claim 4 is characterized in that: A plurality of outer sleeve segments are threadedly connected to form an entire outer sleeve (9), and a plurality of rotating rod segments are threadedly connected to form an entire rotating rod (10).

6. The rock burst monitoring system according to claim 1, characterized in that: One end of the rotating rod (10) and the slot (6.1) are provided with teeth that cooperate with each other, so that the rotating rod (10) can drive the connecting rod (6) to rotate when inserted into the slot (6.1).

7. The rock burst monitoring system according to claim 1, characterized in that: The push rod (5) is provided with a slot (5.2), and the connecting rod (6) is provided with a claw (6.2); the claw (6.2) can rotate in the slot (5.2), and the slot (5.2) limits the position of the claw (6.2) in the left-right direction; The right end of the left end cover (3) is provided with a guide groove I (3.2) and / or the left end of the right end cover (4) is provided with a guide groove II (4.1), and the left end and / or the right end of the upper pressure plate (1) are provided with a guide protrusion (1.2), and the upper pressure plate (1) can move up and down along the guide groove I (3.2) and / or the guide groove II (4.1) via the guide protrusion (1.2).

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