Spiral optical fiber sensor for geophysical prospecting

Abstract

The invention discloses a geophysical prospecting spiral optical fiber sensor, which comprises an outer sheath and an inner sheath, a spiral winding mechanism is arranged between the outer sheath and the inner sheath, the spiral winding mechanism comprises at least three spiral optical fibers arranged in a circumferential array, a composite support core is arranged in the inner sheath, and the spiral angle of the spiral optical fibers is 30-60 degrees; wherein the spiral optical fiber can be adjusted at 30 degrees, 45 degrees and 60 degrees, and particularly relates to communication sensing technical equipment. By adopting a spiral winding structure of a plurality of spiral optical fibers, the lateral sensitivity of the spiral optical fibers is enhanced by using a spiral angle to improve the quality and efficiency of seismic data, and the inner layer is provided with a composite support core which is closer to the outer layer than an optical fiber arranged on a central shaft, so that the sensitivity is further improved; and the spiral angle of the spiral optical fiber can be adjusted through the position of the sensor, so that more accurate measurement precision can be obtained.

Description

Technical Field

[0001] The invention relates to the field of communication sensing technology, in particular to a spiral optical fiber sensor for geophysical exploration. Background Art

[0002] Geophysical fiber optic sensors use the wavelength, intensity and phase of light transmitted to detect the environment by utilizing the fluctuations caused by reflection, absorption and heat dissipation when light encounters the object being measured when the optical fiber transmits light.

[0003] According to patent number CN110268229B, publication (announcement) date: 2021-09-28, a disclosed optical fiber sensor comprises: a central core formed at the center of the optical fiber, and at least one peripheral core formed in a spiral winding manner around the central core, and the ratio of the effective refractive index of the central core to the effective refractive index of the peripheral core is set in such a way that the optical path length difference between the central core and the peripheral core becomes smaller than the optical path length difference when the effective refractive indices of the central core and the peripheral core are the same.

[0004] In the prior art including the above-mentioned patent, the light-guiding optical fiber in the optical fiber sensor is mostly arranged along the axial direction. When the optical fiber is arranged in the axial direction, the area on the axial side that receives the reflected wavelength is limited, resulting in weak fluctuations during detection. When targeting seismic data, the small-frequency afterwaves that arrive in advance are not easy to be detected. Summary of the invention

[0005] The purpose of the present invention is to provide a spiral optical fiber sensor for geophysical exploration, aiming to solve the above problems.

[0006] In order to achieve the above-mentioned object, the present invention provides the following technical solution: a spiral optical fiber sensor for geophysical exploration, comprising an outer sheath and an inner sheath, a spiral winding mechanism is arranged between the two, the spiral winding mechanism comprises at least three spiral optical fibers arranged in a circumferential array, a composite support core is arranged in the inner sheath, and the spiral angle of the spiral optical fiber is 30°~60°; Wherein, the spiral optical fiber is adjusted at 30°, 45° and 60°.

[0007] Preferably, the outer wall of the outer sheath is provided with a spiral expansion groove, the inner wall of the inner sheath is provided with a pulling groove, and the spiral expansion groove includes the following three stations: First station: the spiral expansion groove is driven to stretch and fix to limit the spiral optical fiber to 30°; Second station: the spiral expansion slot is not restricted to drive the spiral optical fiber to 45°; The third station: the spiral expansion groove is driven to shrink and fix to limit the spiral optical fiber to 60°.

[0008] Preferably, a covering spiral strip is arranged in the spiral expansion groove, a plurality of docking posts are arranged on the covering spiral strip, and a through hole penetrating the spiral expansion groove is opened on the outer sheath; Wherein, the spiral expansion groove is driven to switch to the third working position to drive the docking column to be inserted into the through hole for fixing; The covering spiral strip rebounds, driving the spiral expansion groove to maintain the second working position.

[0009] Preferably, it also includes a spiral filling strip, on which elastic buckle plates corresponding to the docking posts are provided, and the spiral filling strip is driven to be clamped on the spiral expansion groove to drive the elastic buckle plate to be clamped on the docking post, so that the spiral expansion groove is driven to switch to the first working position.

[0010] Preferably, the inner wall of the outer sheath and the outer wall of the inner sheath are both provided with matching grooves for limiting the spiral optical fiber.

[0011] Preferably, the composite support core comprises a plurality of hard sleeves arranged in a linear array, and the hard sleeves are provided with telescopic columns inserted into the inner sheath in a circular array.

[0012] Preferably, a stretching portion is provided between the hard sleeves, and the stretching portion corresponds one-to-one to the pulling grooves provided on the inner protective layer.

[0013] Preferably, the hard sleeve is locked in sequence as the spiral expansion groove switches to the third position.

[0014] Preferably, a sheath support portion is provided in the hard sleeve, a conical head is provided at the first end of the sheath support portion, a conical hole facing the second end is opened on the conical head, and the sheath support portion moves as the spiral expansion groove switches to the third station to drive the conical head to be inserted into the conical hole in sequence and locked.

[0015] In the above technical scheme, the spiral fiber optic sensor for geophysical exploration provided by the present invention has the following beneficial effects: by adopting a structure in which multiple spiral optical fibers are spirally wound, the spiral angle is used to enhance the lateral sensitivity of the spiral optical fiber to improve the quality and efficiency of seismic data, and a composite support core is arranged in the inner layer, which is closer to the outer layer than the optical fiber arranged on the central axis, thereby further increasing the sensitivity, and the spiral angle of the spiral optical fiber can be adjusted by the position of the sensor to obtain more precise measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0017] Figure 1 An overall schematic diagram provided for an embodiment of the present invention; Figure 2 An exploded schematic diagram of an outer sheath, a spiral filling strip and a covering spiral strip provided in an embodiment of the present invention; Figure 3 for Figure 2 The enlarged schematic diagram at A in the middle; Figure 4 A schematic diagram of an outer sheath and an inner sheath provided in an embodiment of the present invention; Figure 5 A schematic diagram of an explosion of an inner protective layer and a composite support core provided in an embodiment of the present invention; Figure 6 An overall cross-sectional schematic diagram provided for an embodiment of the present invention; Figure 7 for Figure 6 The enlarged schematic diagram of point B in the middle; Figure 8 A schematic diagram of the helix angle of a helical optical fiber provided in an embodiment of the invention.

[0018] Description of reference numerals: 1. Outer sheath; 111. Spiral expansion groove; 112. Through hole; 113. Anastomosis groove; 12. Inner sheath; 121. Pulling groove; 13. Covering spiral strip; 131. Docking column; 2. Spiral winding mechanism; 21. Spiral optical fiber; 3. Spiral filling strip; 31. Elastic buckle plate; 4. Composite support core; 41. Hard sleeve; 42. Telescopic column; 43. Stretching part; 44. Sheath support part; 441. Conical hole; 442. Conical head. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0020] like Figure 1-8As shown, a spiral optical fiber sensor for geophysical exploration comprises an outer sheath 1 and an inner sheath 12, a spiral winding mechanism 2 is arranged between the outer sheath 1 and the inner sheath 12, the spiral winding mechanism 2 comprises at least three spiral optical fibers 21 arranged in a circumferential array, a composite support core 4 is arranged in the inner sheath 12, and the spiral angle of the spiral optical fiber 21 is 30° to 60°; The spiral optical fiber 21 is adjusted at 30°, 45° and 60°.

[0021] Specifically, the helical angle of the helical optical fiber 21 is Figure 8 As shown, with the central axis of the outer sheath 1 and the inner sheath 12 as a reference, the angle with the inclination direction of the spiral optical fiber 21 is 30°~60°. When in use, all the spiral optical fibers 21 are adjusted to an angle according to the accuracy and position required for detection, and the angle can be 30°, 45° and 60°, thereby increasing the lateral sensitivity of the spiral optical fiber 21 to improve the quality and efficiency of seismic data. The spiral optical fiber 21 in the outer layer is easier to be penetrated by light than that arranged along the central axis, so it can detect seismic data more sensitively.

[0022] In the above technical solution, a structure in which multiple spiral optical fibers 21 are spirally wound is adopted, and the helix angle is used to enhance the lateral sensitivity of the spiral optical fiber 21 to improve the quality and efficiency of seismic data. A composite support core 4 is arranged in the inner layer, which is closer to the outer layer than the optical fiber arranged on the central axis, thereby further increasing the sensitivity. The helix angle of the spiral optical fiber 21 can also be adjusted by the position of the sensor to obtain more precise measurement accuracy.

[0023] Furthermore, the spiral optical fiber 21 uses a bend-insensitive spiral optical fiber, and the optical fiber must take macrobending loss into consideration. The optical fiber attenuation index after cabling is ≤1dB at a wavelength of 1550nm.

[0024] As an embodiment provided by the present invention, a spiral expansion groove 111 is provided on the outer wall of the outer sheath 1, and a pulling groove 121 is provided on the inner wall of the inner protective layer 12. The spiral expansion groove 111 includes the following three stations: First station: the spiral expansion slot 111 is driven to stretch and fix, so as to limit the spiral optical fiber 21 to 30°; Second station: the spiral expansion slot 111 is not restricted to drive the spiral optical fiber 21 to 45°; The third station: the spiral expansion groove 111 is driven to shrink and fix, so as to limit the spiral optical fiber 21 to 60 degrees.

[0025] Specifically, the spiral expansion groove 111 and the pulling groove 121 are both made of elastic materials, so as to realize the pulling of the sensor. Before setting the sensor, the position of the spiral expansion groove 111 is switched as needed, and the sensor is elongated by stretching, so that the spiral expansion groove 111 is switched to the first position for fixing, so that the thread angle of the spiral optical fiber 21 is 30°. At this time, although the spiral optical fiber 21 is still in a threaded state, its lateral sensitivity is improved, but the number of spiral optical fibers 21 is small under the same unit length, which is suitable for being set at a position with high reflection intensity and easy transmission of light and sound waves. At a position with medium reflection intensity, the spiral expansion groove 111 is switched to the second position, thereby increasing the number of spiral optical fibers 21 under the same unit length and changing the angle of the spiral optical fiber 21, so that the transmission of light and sound waves is easier to detect. At a position with low reflection intensity, high density, and very difficult transmission of light and sound waves, the spiral expansion groove 111 is switched to the third position, at which the spiral angle of the spiral optical fiber 21 is limited to 60°, and the spiral expansion groove 111 is driven to shrink and fix, so as to increase the number of spiral optical fibers 21 under the same unit length, so as to achieve the effect of accurate measurement.

[0026] As an embodiment provided by the present invention, a covering spiral strip 13 is arranged in the spiral expansion slot 111, and a plurality of docking posts 131 are arranged on the covering spiral strip 13. A through hole 112 penetrating the spiral expansion slot 111 is opened on the outer sheath 1; The spiral expansion slot 111 is driven to switch to the third position to drive the docking column 131 to be inserted into the through hole 112 and fixed; The covering spiral strip 13 rebounds, driving the spiral expansion groove 111 to maintain the second working position.

[0027] Specifically, a covering spiral strip 13 is provided in the spiral expansion groove 111. The covering spiral strip 13 is made of elastic plastic and hard plastic, has good elasticity and certain supporting capacity. When the spiral expansion groove 111 is not restricted by external objects, when the spiral expansion groove 111 needs to be switched to the third station, the outer sheath 1 is held and squeezed, and rotated slightly to make the two sides of the spiral expansion groove 111 fit together, and the docking column 131 is inserted into the through hole 112 to fix the spiral expansion groove 111 in the third station. When it is necessary to switch to the second station, the outer sheath 1 is held and pulled to drive the docking column 131 to decouple from the through hole 112, and then the elasticity of the covering spiral strip 13 drives the rebound, thereby maintaining the second station of the spiral expansion groove 111.

[0028] When precise measurement is required, the outer sheath 1 is squeezed and rotated slightly to fit the two sides of the spiral expansion groove 111 and insert the docking post 131 into the through hole 112. At this time, the spiral angle of the spiral optical fiber 21 is limited to 60°, and the spiral expansion groove 111 is driven to shrink and fix, so as to increase the number of spiral optical fibers 21 under the same unit length. When the installation position has a medium reflection intensity, the outer sheath 1 is pulled to drive the docking post 131 to decouple from the through hole 112, and then the elasticity of the covering spiral strip 13 drives the rebound, so as to maintain the second position of the spiral expansion groove 111. When the reflection intensity is high, the outer sheath 1 is driven to stretch and lengthen, so that the spiral expansion groove 111 is switched to the first position and fixed.

[0029] As an embodiment provided by the present invention, it also includes a spiral filling strip 3, on which an elastic buckle plate 31 corresponding to the docking column 131 is provided. The spiral filling strip 3 is driven to be clamped on the spiral expansion groove 111 to drive the elastic buckle plate 31 to be clamped on the docking column 131, so that the spiral expansion groove 111 is driven to switch to the first working position.

[0030] Specifically, the spiral filling strip 3 is a hard plastic strip, and the hard plastic strip can be provided with foam material. When it is necessary to switch the spiral expansion groove 111 to the first station, the elastic buckle plate 31 on the spiral filling strip 3 is snapped onto the docking column 131, and then the spiral filling strip 3 is squeezed into the spiral expansion groove 111 for filling, thereby squeezing the spiral expansion groove 111 and the pulling groove 121 for stretching to change the spiral angle of the spiral optical fiber 21 to 60°. Stretching by filling can extend the use time, and it is not easy to be damaged or change the spiral angle.

[0031] When precise measurement is required, the outer sheath 1 is held and squeezed, and rotated slightly to make the two sides of the spiral expansion groove 111 fit together, and the docking post 131 is inserted into the through hole 112. At this time, the spiral angle of the spiral optical fiber 21 is limited to 60°, and the spiral expansion groove 111 is driven to shrink and fix, so as to increase the number of spiral optical fibers 21 under the same unit length. When the installation position has a medium reflection intensity, the outer sheath 1 is held and pulled to drive the docking post 131 to decouple from the through hole 112, and then the elastic drive of the covering spiral strip 13 rebounds, thereby maintaining the second position of the spiral expansion groove 111. When the reflection intensity is high, the elastic buckle plate 31 on the spiral filling strip 3 is snapped onto the docking post 131, and then the spiral filling strip 3 is squeezed into the spiral expansion groove 111 for filling, thereby squeezing the spiral expansion groove 111 and the pulling groove 121 for stretching, so that the spiral expansion groove 111 is switched to the first position for fixing.

[0032] Furthermore, both the inner wall of the outer sheath 1 and the outer wall of the inner protective layer 12 are provided with matching grooves 113 for limiting the spiral optical fiber 21 .

[0033] Specifically, the two groups of matching grooves 113 overlap with each other to clamp the spiral optical fiber 21 . When the outer sheath 1 and the inner sheath 12 move together, the two groups of matching grooves 113 keep matching and clamping the spiral optical fiber 21 to protect the spiral optical fiber 21 .

[0034] As an embodiment provided by the present invention, the composite support core 4 includes a plurality of hard sleeves 41 arranged in a linear array, and the hard sleeves 41 are provided with telescopic columns 42 inserted into the inner protective layer 12 in a circumferential array.

[0035] Specifically, the hard sleeves 41 are connected in a series to support the inner protective layer 12 to increase the overall pressure resistance of the sensor. The hard sleeves 41 are provided with telescopic columns 42 inserted into the inner protective layer 12 in a circular array. The telescopic columns 42 increase the connection between the composite support core 4 and the inner protective layer 12, and when the inner protective layer 12 and the outer sheath 1 move, the hard sleeves 41 are driven to move together, thereby increasing the overall support without affecting the telescopic d1 of the outer sheath 1.

[0036] When precise measurement is required, the outer sheath 1 is squeezed and rotated slightly to fit the two sides of the spiral expansion groove 111 and insert the docking post 131 into the through hole 112. At this time, the spiral angle of the spiral optical fiber 21 is limited to 60°, and the spiral expansion groove 111 is driven to shrink and fix to increase the number of spiral optical fibers 21 under the same unit length. When the reflection intensity of the installation position is medium, the outer sheath 1 is pulled to drive the docking post 131 to decouple from the through hole 112, and then the spiral strip 13 is covered. The elasticity drives the rebound, thereby maintaining the second position of the spiral expansion groove 111. When the reflection intensity is high, the elastic buckle plate 31 on the spiral filling strip 3 is clamped on the docking column 131, and then the spiral filling strip 3 is squeezed into the spiral expansion groove 111 for filling, thereby squeezing the spiral expansion groove 111 and the pulling groove 121 for stretching, so that the spiral expansion groove 111 is switched to the first position and fixed. During the process of switching the position of the spiral expansion groove 111, the hard sleeve 41 will slide accordingly to maintain support.

[0037] Furthermore, a stretching portion 43 is provided between the hard sleeves 41. The stretching portion 43 is made of elastic plastic. The stretching portion 43 corresponds one-to-one to the pulling groove 121 provided on the inner protective layer 12, so that when the inner protective layer 12 is stretched or contracted, the stretching portion 43 is driven to move together. The stretching portion 43 increases the tensile strength of the overall sensor, and stretches and contracts with the switching of the spiral expansion groove 111 station, thereby realizing the overall expansion and contraction capability of the sensor.

[0038] As the best embodiment provided by the present invention, the hard sleeve 41 is locked in sequence as the spiral expansion slot 111 switches to the third position; A sheath support portion 44 is provided in the hard sleeve 41, a cone head 442 is provided at the first end of the sheath support portion 44, a cone hole 441 facing the second end is opened on the cone head 442, and the sheath support portion 44 moves as the spiral expansion groove 111 switches to the third station to drive the cone head 442 to be inserted into the cone hole 441 in sequence and locked.

[0039] Specifically, a sheath support portion 44 is provided in the hard sleeve 41, and the sheath support portion 44 is used to increase the pressure resistance of the entire sensor. Figure 7 As shown, the first end is the upper end, and the second end is the lower end. A cone head 442 is provided at the first end of the sheath support portion 44. A cone hole 441 facing the second end is opened on the cone head 442. The circular cross-section of the cone hole 441 is larger than the circular cross-section of the cone head 442. Therefore, when the spiral expansion groove 111 is switched to the third station, the hard sleeve 41 is driven to slide, so that the cone head 442 is inserted into the connected cone hole 441 and locked by the taper. After locking, the connected cone head 442 and cone hole 441 are fixed to each other and cannot be opened from the middle, thereby increasing consistency. Therefore, when the geology is prone to change, the third station is adopted to reinforce the overall sensor. At the same time, the mutually locked cone head 442 and cone hole 441 will also limit the overall bending angle to protect the spiral optical fiber 21.

[0040] Furthermore, a small-sized circle is provided in the middle of the stretching portion 43, and the small-sized circle is made of hard plastic. When the overall sensor is in the first station or the second station and is bent during the arrangement process, the cone head 442 is not inserted into the cone hole 441. During the bending process, the cone head 442 will rotate and move. The greater the bending amplitude, the greater the range of movement. During the bending process, the cone head 442 is restricted by the small-sized circle, resulting in a limited bending angle, so that the maximum bending angle of the local sensor is limited, thereby avoiding the spiral optical fiber 21 from breaking or losing its light-guiding ability due to a large bending angle.

[0041] When precise measurement is required, the outer sheath 1 is squeezed and rotated slightly to fit the two sides of the spiral expansion groove 111, and the docking post 131 is inserted into the through hole 112. At this time, the spiral angle of the spiral optical fiber 21 is limited to 60°, and the spiral expansion groove 111 is driven to shrink and fix, so as to increase the number of spiral optical fibers 21 under the same unit length, and slide with the hard sleeve 41, so as to insert the cone head 442 into the connected cone hole 441, and lock it by the taper. When the reflection intensity of the installation position is medium, the outer sheath 1 is pulled by hand to drive the docking post 131 to decouple from the through hole 112, and then the elasticity of the spiral strip 13 drives the rebound, so as to maintain At the second station of the spiral expansion groove 111, when the reflection intensity is high, the elastic buckle plate 31 on the spiral filling strip 3 is snapped onto the docking column 131, and then the spiral filling strip 3 is squeezed into the spiral expansion groove 111 for filling, thereby squeezing the spiral expansion groove 111 and the pulling groove 121 for stretching, so that the spiral expansion groove 111 is switched to the first station for fixing. During the station switching of the spiral expansion groove 111, the hard sleeve 41 will slide accordingly. During the underground arrangement of the spiral expansion groove 111 at the first station and the second station, the cone head 442 will be restricted by the small-size circle on the stretching part 43, thereby limiting the maximum bending angle and protecting the sensor.

[0042] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A spiral optical fiber sensor for geophysical exploration, characterized in that: It comprises an outer sheath (1) and an inner sheath (12), a spiral winding mechanism (2) being arranged between the two, the spiral winding mechanism (2) comprising at least three spiral optical fibers (21) arranged in a circumferential array, a composite support core (4) being arranged in the inner sheath (12), and a spiral angle of the spiral optical fiber (21) being 30° to 60°; The spiral optical fiber (21) is adjusted at 30°, 45° and 60°.

2. The spiral optical fiber sensor for geophysical exploration according to claim 1, characterized in that: The outer wall of the outer sheath (1) is provided with a spiral expansion groove (111), the inner wall of the inner protective layer (12) is provided with a pulling groove (121), and the spiral expansion groove (111) comprises the following three workstations: First workstation: the spiral expansion groove (111) is driven to stretch and fix, so as to limit the spiral optical fiber (21) to 30°; Second workstation: the spiral expansion slot (111) is not restricted, so as to drive the spiral optical fiber (21) to 45°; Third workstation: the spiral expansion groove (111) is driven to shrink and be fixed, so as to limit the spiral optical fiber (21) to 60 degrees.

3. The spiral optical fiber sensor for geophysical exploration according to claim 2, characterized in that: A covering spiral strip (13) is arranged in the spiral expansion groove (111), a plurality of docking posts (131) are arranged on the covering spiral strip (13), and a through hole (112) penetrating the spiral expansion groove (111) is provided on the outer sheath (1); The spiral expansion slot (111) is driven to switch to the third working position, so as to drive the docking column (131) to be inserted into the through hole (112) and fixed; The covering spiral strip (13) rebounds, driving the spiral expansion groove (111) to maintain the second working position.

4. The spiral optical fiber sensor for geophysical exploration according to claim 3, characterized in that: It also comprises a spiral filling strip (3), on which elastic buckle plates (31) corresponding one to one with the docking posts (131) are arranged, and the spiral filling strip (3) is driven to be clamped on the spiral expansion slot (111) to drive the elastic buckle plate (31) to be clamped on the docking post (131), so that the spiral expansion slot (111) is driven to switch to the first working position.

5. The spiral optical fiber sensor for geophysical exploration according to claim 1, characterized in that: The inner wall of the outer sheath (1) and the outer wall of the inner protective layer (12) are both provided with anastomotic grooves (113) for restricting the spiral optical fiber (21).

6. The spiral optical fiber sensor for geophysical exploration according to claim 2, characterized in that: The composite support core (4) comprises a plurality of hard sleeves (41) arranged in a linear array, and the hard sleeves (41) are provided with telescopic columns (42) inserted into the inner protective layer (12) in a circumferential array.

7. The spiral optical fiber sensor for geophysical exploration according to claim 6, characterized in that: A stretching portion (43) is provided between the hard sleeves (41), and the stretching portion (43) corresponds one-to-one to the pulling grooves (121) provided on the inner protective layer (12).

8. The spiral optical fiber sensor for geophysical exploration according to claim 7, characterized in that: The hard sleeve (41) is locked in sequence as the spiral expansion slot (111) switches to the third working position.

9. The spiral optical fiber sensor for geophysical exploration according to claim 8, characterized in that: A sheath support portion (44) is arranged in the hard sleeve (41), a cone head (442) is arranged at a first end of the sheath support portion (44), a cone hole (441) facing the second end is opened on the cone head (442), and the sheath support portion (44) moves as the spiral expansion groove (111) switches to the third working position, so as to drive the cone head (442) to be inserted into the cone hole (441) in sequence and locked.

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