A pressure-controlled expandable centralizing mechanism

Abstract

The present invention provides a pressure-controlled expansion type centralizing mechanism, which includes a centralizer body. An expansion sleeve is sleeved outside the centralizer body. A metal support plate is arranged on the outer side wall of the expansion sleeve. A rotating sleeve is rotatably arranged inside the centralizer body. A piston rod is arranged inside the rotating sleeve. Piston heads are arranged at both ends of the piston rod. A left limit sleeve is arranged on the left side of the left piston head. A sliding piston body is arranged at the right end of the right piston head. A compression spring is sleeved outside the sliding piston body. A right limit sleeve is arranged on the right side of the sliding piston body. The present invention can adjust the drilling direction with the downhole survey instrument during the drilling process of a mine directional drill as needed. During drilling, the pressure-controlled expansion type centralizing mechanism supports the borehole coal wall. After the direction adjustment is completed, the centralizer returns to its original position without affecting drilling. It is convenient to operate and use, has good stability, and improves the drilling accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of expandable centralizing mechanisms, and particularly to a pressure-controlled expandable centralizing mechanism. Background Art

[0002] Most of the existing centralizers are non-tension alloy centralizers, which are wear-resistant and high-temperature resistant. The disadvantage is that when encountering soft coal seams or voids in coal and rock, they cannot adjust the drilling direction according to the measurement-while-drilling instrument, and cannot effectively play a centralizing role, resulting in poor drilling accuracy. Moreover, the centralizing pieces of the non-tension alloy centralizer are always located outside the drill pipe during drilling, which will inevitably increase the diameter of the drill pipe invisibly during drilling, thereby increasing the resistance during drill pipe drilling. In severe cases, it may even affect the normal drilling work of directional drilling. Summary of the Invention

[0003] In view of this, the present invention provides a pressure-controlled expandable centralizing mechanism, which can adjust the drilling direction according to the measurement-while-drilling instrument as needed during the drilling process of a mine directional drill. During drilling, the pressure-controlled expandable centralizing mechanism supports the coal wall of the borehole. After the direction adjustment is completed, the centralizer returns to its original position without affecting drilling. It is convenient to operate and use, has good stability, increases the centralizing effect, and improves the drilling accuracy.

[0004] To solve the above technical problems, the present invention provides a pressure-controlled expandable centralizing mechanism, including a centralizer body. The centralizer body is cylindrical. An expansion sleeve is sleeved outside the centralizer body, and both ends of the expansion sleeve are fixed on the centralizer body. A plurality of metal support plates are evenly arranged on the outer side wall of the expansion sleeve. A rotating sleeve is rotatably arranged inside the centralizer body. A plurality of high-pressure medium inlets are arranged circumferentially on the outer side wall of the left side of the rotating sleeve. A high-pressure medium guiding hole adapted to the high-pressure medium inlet is opened on the outer side wall of the centralizer body. A plurality of high-pressure medium outlets are arranged circumferentially on the outer side wall of the right side of the rotating sleeve. A high-pressure medium discharge hole adapted to the high-pressure medium outlet is arranged inside the rotating sleeve. A piston rod is slidably arranged inside the rotating sleeve. Piston heads are arranged at both ends of the piston rod. A left limit sleeve is arranged on the left side of the left piston head. A sliding piston body is arranged at the right end of the right piston head. A compression spring is sleeved outside the sliding piston body. A right limit sleeve is arranged on the right side of the sliding piston body.

[0005] The high-pressure medium supplied to the drill pipe by the water supply device in the present invention. Here, high pressure can select high-pressure water. It should be clear that when the high-pressure medium is not pressurized, the restoring elastic force of the compression spring is greater than the pressure of the medium. After the medium is pressurized, under the action of the high pressure of the high-pressure medium, the piston head on the left is pushed to drive the piston rod to move to the right, and the piston head on the right will push the sliding piston body to move to the right, thereby further compressing the compression spring. When the pressure reaches the minimum compression length of the compression spring, the piston head on the left will move to the right side of the high-pressure medium inlet, and the piston head on the right will move to block the high-pressure medium discharge port. At this time, the high-pressure medium inlet will open, and at the same time the outlet will close. The high-pressure medium will flow into the high-pressure medium guiding hole through the water inlet and finally enter the expansion sleeve. At this time, the expansion sleeve will expand rapidly due to the injection of the high-pressure medium, and then push the metal support plate located outside the expansion sleeve to move outward until it closely adheres to the coal wall, thereby realizing the function of straightening and supporting. When drilling in this coal seam or the bottom extraction roadway, while the drill rig rotates and drills, it will drive the rotating sleeve to rotate together. At this time, the straightening mechanism does not move. At the same time, when turning is required, the supply of the high-pressure medium is stopped. At this time, due to the tension of the compression spring being greater than the pressure of the medium, the piston rod will return to its original position under the action of the tension of the compression spring. At this time, the inlet closes, the outlet opens, and the medium will flow out through the high-pressure medium discharge port and be discharged through the high-pressure medium outlet hole. Since the medium in the expansion sleeve decreases, the expansion sleeve will shrink, and at the same time the metal support plate will retract.

[0006] The axial section of the sliding piston body is cross-shaped. A first annular sealing ring is arranged between the maximum diameter of the sliding piston body and the inner side wall of the rotating sleeve. One end of the compression spring is arranged on the right end face of the vertical part of the maximum diameter of the sliding piston body, and the other end of the compression spring is arranged on the left side wall of the vertical part of the right limit sleeve. A high-pressure medium outlet hole is penetrated through the left side of the sliding piston body. The first annular sealing ring should be made of rubber material with high compressive resistance, wear resistance and high temperature resistance. The first annular sealing ring can avoid the leakage of the medium and can realize the effective sealing between the sliding piston body and the inner side wall of the rotating sleeve.

[0007] A wear-resistant sleeve is arranged outside the rotating sleeve and inside the straightening device main body. The rotating sleeve is rotatably arranged in the wear-resistant sleeve.

[0008] A second annular sealing ring is arranged on the outer side wall of the piston head. The second annular sealing ring should be made of rubber material with high compressive resistance, wear resistance and high temperature resistance. The second annular sealing ring can avoid the leakage of the medium and can realize the effective sealing between the piston head and the inner side wall of the rotating sleeve.

[0009] At both the left and right ends of the centralizer body, there are compression sleeves for fixing the ends of the expansion sleeve. An annular groove is provided on the inner side wall of the vertical part of the compression sleeve. An expansion locking ring is provided in the annular groove and on the outer side wall of the centralizer. The two ends of the expansion sleeve are fixed on the outer side wall of the centralizer body through the expansion locking ring. The outer side wall of the expansion sleeve is in contact with the inner side wall of the expansion locking ring, and the outer side wall of the expansion locking ring is in contact with the inner side wall of the annular groove. The expansion locking ring can be used to compress and fix the expansion sleeve on one hand, and can increase the tightness of the connection between the compression sleeve and the centralizer body on the other hand.

[0010] There are 8 metal support plates, which are evenly distributed on the axial outer side wall of the expansion sleeve. The metal support plates should be made of steel plates that are resistant to compression, wear, and not easily deformed. The metal support plates are used to support the coal wall and straighten the drilling of the drill bit, which is beneficial to improving the drilling accuracy, increasing the straightening effect, and enhancing the stability of the drilling rig during drilling.

[0011] In summary, compared with the prior art, the present application includes at least one of the following beneficial technical effects:

[0012] 1. Under the action of the high pressure of the high-pressure medium, the high-pressure medium will push the piston head on the left to drive the piston rod to move to the right, and the piston head on the right will push the sliding piston body to move to the right, thereby further compressing the compression spring. When the pressure reaches the minimum compression length of the compression spring, the piston head on the left will move to the right side of the high-pressure medium inlet, and the piston head on the right will move to block the high-pressure medium discharge port. At this time, the high-pressure medium inlet will open, and at the same time the outlet will close. The high-pressure medium will flow into the high-pressure medium guiding hole through the water inlet and finally enter the expansion sleeve. At this time, the expansion sleeve will expand rapidly due to the injection of the high-pressure medium, and then push the metal support plates located outside the expansion sleeve to move outward until they are close to the coal wall, thereby achieving the straightening and supporting effect.

[0013] 2. When drilling in the coal seam or the bottom gas drainage roadway, when the drilling rig rotates during rotary drilling, it will drive the rotating sleeve to rotate together, and at this time the straightening mechanism does not move. At the same time, when steering is required, the supply of the high-pressure medium is stopped. At this time, due to the tension of the compression spring being greater than the pressure of the medium, the piston rod will return to its original position under the action of the tension of the compression spring. At this time, the inlet is closed and the outlet is opened, and the medium will flow out through the high-pressure medium discharge port to the high-pressure medium guiding hole and finally be discharged through the second water guiding hole. Since the medium in the expansion sleeve decreases, the expansion sleeve will shrink, and at the same time the metal support plates will retract.

[0014] 3. The first annular sealing ring can prevent the leakage of the medium and can effectively seal between the sliding piston body and the inner side wall of the rotating sleeve.

[0015] 4. The metal support plate should be made of steel plate material that is compression-resistant, wear-resistant, and not prone to deformation. The purpose is to improve the support effect of the metal support plate, and under the expansion action of the expansion sleeve, drive the metal support plate to support the coal wall outward and straighten the drill bit during drilling, which is beneficial to improving the drilling accuracy, increasing the straightening effect, and enhancing the stability of the drill during drilling. The second annular seal should be made of rubber material that is compression-resistant, wear-resistant, and high-temperature resistant. The second annular seal can prevent the leakage of the medium and achieve effective sealing between the piston head and the inner wall of the rotating sleeve.

[0016] 5. The pressure-controlled expansion type straightening mechanism can adjust the drilling direction according to the needs of the downhole measuring instrument during the drilling process of the mine directional drill. During drilling, the pressure-controlled expansion type straightening mechanism supports the coal wall of the borehole. After the direction adjustment is completed, the straightener returns to its original position without affecting drilling. The overall structure is simple, easy to operate and use, has good stability, high reliability, simple manufacturing process, increases the straightening effect, and improves the drilling accuracy. Brief Description of the Drawings

[0017] Figure 1 It is a schematic structural diagram of the pressure-controlled expansion type straightening mechanism of the present invention in the closed state;

[0018] Figure 2 It is a left view of the pressure-controlled expansion type straightening mechanism of the present invention in the closed state;

[0019] Figure 3 It is a schematic structural diagram of the pressure-controlled expansion type straightening mechanism of the present invention in the open state;

[0020] Figure 4 It is a left view of the pressure-controlled expansion type straightening mechanism of the present invention in the open state;

[0021] Figure 5 It is an enlarged view of the structure at A in the present invention.

[0022] Description of the Reference Numerals in the Drawings: 100, straightener body; 200, expansion sleeve; 300, metal support plate; 400, rotating sleeve; 500, high-pressure medium inlet; 600, high-pressure medium guiding hole; 700, high-pressure medium discharge port; 800, high-pressure medium discharge hole; 110, piston rod; 210, piston head; 310, left limit sleeve; 410, sliding piston body; 510, compression spring; 610, right limit sleeve; 710, high-pressure medium outlet hole; 810, first annular seal; 910, wear-resistant sleeve; 120, second annular seal; 220, compression sleeve; 320, annular groove; 420, expansion locking ring. Detailed Embodiment

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will combine the drawings of the embodiments of the present invention Figures 1-5, the technical solutions of the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

[0024] Such as Figures 1-5Shown as follows: This embodiment provides a pressure-controlled expandable centralizing mechanism, including a centralizer body 100. The centralizer body 100 is cylindrical. An expansion sleeve 200 is sleeved outside the centralizer body 100, and both ends of the expansion sleeve 200 are fixed on the centralizer body 100. The expansion sleeve 200 should be selected as a rubber sleeve with good deformation ability, compression resistance and wear resistance. A plurality of metal support plates 300 are evenly arranged on the outer side wall of the expansion sleeve 200. The metal support plates 300 should be selected as steel plates with good rigidity and not prone to deformation. A rotating sleeve 400 is rotatably arranged inside the centralizer body 100. A plurality of high-pressure medium inlets 500 are arranged along the circumferential direction on the outer side wall of the left side of the rotating sleeve 400. The number of the high-pressure medium inlets 500 should be any required number such as 8 - 36. The high-pressure medium inlets 500 are used for the entry of high-pressure medium. A high-pressure medium guiding hole 600 adapted to the high-pressure medium inlet 500 is opened on the outer side wall of the centralizer body 100. The number of the high-pressure medium guiding holes 600 should be more than the number of the high-pressure medium inlets 500. At the same time, the high-pressure medium guiding hole 600 can also be designed as a through groove, and the through groove is arranged along the circumferential direction on the outer side wall of the centralizer body. The high-pressure medium guiding hole 600 is used to guide the high-pressure medium flowing in through the high-pressure medium inlet 500 into the expansion sleeve 200 to realize the expansion of the expansion sleeve 200. A plurality of high-pressure medium outlets 700 are arranged along the circumferential direction on the outer side wall of the right side of the rotating sleeve 400. The number of the high-pressure medium discharge holes 700 should be any required number such as 8 - 36. A high-pressure medium discharge hole 800 adapted to the high-pressure medium outlet 700 is arranged inside the rotating sleeve 400. The number of the high-pressure medium discharge holes 800 should be more than the number of the high-pressure medium outlets 700. The high-pressure medium discharge hole 800 can also be designed as a through groove, and the through groove is arranged along the circumferential direction on the outer side wall of the centralizer body. The high-pressure medium discharge hole 800 is used to discharge the high-pressure medium in the expansion sleeve 200, flow through the high-pressure medium outlet 700, and finally be discharged through the high-pressure medium discharge port. A piston rod 110 is slidably arranged inside the rotating sleeve 400. The piston rod 110 should be selected as steel with good rigidity. Piston heads 210 are arranged at both ends of the piston rod 110. The piston heads 210 should be selected as rubber materials with compression resistance, wear resistance and high temperature resistance. A left limit sleeve 310 is arranged on the left side of the left piston head 210. The left limit sleeve 310 is used to limit the position of the left piston head 210. A sliding piston body 410 is arranged at the right end of the right piston head 210. A compression spring 510 is sleeved outside the sliding piston body 410. A right limit sleeve 610 is arranged on the right side of the sliding piston body 410. The left limit sleeve 310 and the right limit sleeve 610 can be threadedly connected or welded to the inner side wall of the rotating sleeve 400. The right limit sleeve 610 is used to limit the right side of the sliding piston body 410. In the present invention, the high-pressure medium supplied to the drill pipe by the water supply device. Here, the high-pressure medium can be selected as high-pressure water, high-pressure gas such as high-pressure nitrogen, or medium such as wind. It should be clear that,When the high-pressure medium is not pressurized, the restoring elastic force of the compression spring 510 is greater than the pressure of the medium. After the medium is pressurized, under the action of the high pressure of the high-pressure medium, the piston head 210 on the left is pushed to drive the piston rod 110 to move to the right. The piston head 210 on the right will push the sliding piston body 410 to move to the right, further compressing the compression spring 510. When the pressure reaches the minimum compression length of the compression spring 510, the piston head 210 on the left will move to the right side of the high-pressure medium inlet 500, and the piston head 210 on the right will move to block the high-pressure medium discharge port 700. At this time, the high-pressure medium inlet 500 will open, and at the same time the high-pressure medium discharge port 700 will close. The high-pressure medium will flow into the high-pressure medium guiding hole 600 through the high-pressure medium inlet 500 and finally enter the expansion sleeve 200. At this time, the expansion sleeve 200 will expand rapidly due to the injection of the high-pressure medium, and then push the metal support plate 300 located outside the expansion sleeve 200 to move outward until it is close to the coal wall, thus realizing the function of straightening and supporting. When drilling in this coal seam or the bottom extraction roadway, while the drill rotates and drills, it will drive the rotating sleeve 400 to rotate together, and at this time the straightening mechanism does not move. At the same time, when steering is required, the supply of high-pressure medium is stopped. At this time, due to the tension of the compression spring 510 being greater than the pressure of the medium, the piston rod 110 will return to its original position under the action of the tension of the compression spring 510. At this time, the high-pressure medium inlet 500 will close, and the high-pressure medium discharge port 700 will open. The medium will flow out through the high-pressure medium discharge port 700 to the high-pressure medium outlet hole 710 and finally be discharged through the second water guiding hole 900. Since the medium in the expansion sleeve 200 decreases, the expansion sleeve 200 will shrink, and at the same time the metal support plate 300 will retract.

[0025] According to an embodiment of the present invention, as Figure 1 and Figure 2 shown, the axial section of the sliding piston body 410 is cross-shaped. A first annular sealing ring 810 is provided between the maximum diameter of the sliding piston body 410 and the inner side wall of the rotating sleeve 400. One end of the compression spring 510 is arranged on the right end face of the vertical part of the maximum diameter of the sliding piston body 410, and the other end of the compression spring 510 is arranged on the left side wall of the vertical part of the right limit sleeve 610. A high-pressure medium outlet hole 710 is penetrated through the left axis of the sliding piston body 410. Here, the high-pressure medium outlet hole 710 is used to guide the high-pressure medium to the drill bit or water drill on the right for cooling the drill bit or water drill. The first annular sealing ring 810 should be made of a rubber material with high compressive resistance, wear resistance and high temperature resistance. The first annular sealing ring 810 can prevent the leakage of the medium and can effectively seal between the sliding piston body 410 and the inner side wall of the rotating sleeve 400.

[0026] According to another embodiment of the present invention, as Figure 1 and Figure 2As shown, a wear-resistant sleeve 910 is provided on the outer side of the rotating sleeve 400 and inside the centralizer body 100, and the rotating sleeve 400 is rotatably arranged within the wear-resistant sleeve 910.

[0027] According to another embodiment of the present invention, as Figure 1 and Figure 2 shown, a second annular sealing ring 120 is provided on the outer side wall of the piston head 210. The second annular sealing ring 120 should be made of a rubber material that is resistant to compression, wear, and high temperatures. The second annular sealing ring 120 can prevent the leakage of the medium and can achieve effective sealing between the piston head 210 and the inner side wall of the rotating sleeve 400.

[0028] According to another embodiment of the present invention, as Figures 1-5 shown, pressing sleeves 220 for fixing the ends of the expansion sleeve 200 are provided at both the left and right ends of the centralizer body 100.

[0029] According to another embodiment of the present invention, as Figures 1-5 shown, an annular groove 320 is provided on the inner side wall of the vertical portion of the pressing sleeve 220, and an expansion locking ring 420 is provided on the outer side wall of the centralizer within the annular groove 320. The two ends of the expansion sleeve 200 are fixed to the outer side wall of the centralizer body 100 through the expansion locking ring 420. The outer side wall of the expansion sleeve 200 is in contact with the inner side wall of the expansion locking ring 420, and the outer side wall of the expansion locking ring 420 is in contact with the inner side wall of the annular groove 320. The expansion locking ring 420 can be used to press and fix the expansion sleeve 200 on the one hand, and can increase the tightness of the connection between the pressing sleeve 220 and the centralizer body 100 on the other hand.

[0030] According to another embodiment of the present invention, as Figure 5 shown, there are 8 metal support plates 300, which are evenly distributed on the axial outer side wall of the expansion sleeve 200. The metal support plates 300 should be made of steel plates that are resistant to compression, wear, and not prone to deformation. The metal support plates 300 are used to support the coal wall and straighten the drilling of the drill bit, which is beneficial to improving the drilling accuracy, increasing the straightening effect, and enhancing the stability of the drilling of the drill rig.

[0031] The usage method of the present invention:

[0032] First of all, it should be clear that the present invention is used to straighten the drill bit and support the coal wall during the drilling process of a mine directional drill in a coal seam or coal and rock. The present invention uses a high-pressure medium supplied by a water supply device to the drill pipe, and realizes the expansion type straightening of the mechanism through the high-pressure medium. The high-pressure medium here can be high-pressure water, high-pressure gas such as high-pressure nitrogen, or other media such as wind. It should be clear that when the high-pressure medium is not pressurized, the restoring elastic force of the compression spring 510 is greater than the pressure of the medium. When the medium is pressurized, under the action of the high pressure of the high-pressure medium, the piston head 210 on the left is pushed to drive the piston rod 110 to move to the right, and the piston head 210 on the right will push the sliding piston body 410 to move to the right, further compressing the compression spring 510. When the pressure reaches the minimum compression length of the compression spring 510, the piston head 210 on the left will move to the right side of the high-pressure medium inlet 500, and the piston head 210 on the right will move to block the high-pressure medium discharge port 700. At this time, the high-pressure medium inlet 500 will open, and at the same time the high-pressure medium discharge port 700 will close. The high-pressure medium will flow into the high-pressure medium guiding hole 600 through the high-pressure medium inlet 500 and finally enter the expansion sleeve 200. At this time, the expansion sleeve 200 will expand rapidly due to the injection of the high-pressure medium, and then push the metal support plate 300 located outside the expansion sleeve 200 to move outward until it closely adheres to the coal wall, thus realizing the straightening and supporting effect. When drilling in this coal seam or the bottom extraction roadway, when the drill rotates, it will drive the rotating sleeve 400 to rotate together, and at this time the straightening mechanism does not move. At the same time, when turning is required, the supply of the high-pressure medium is stopped. At this time, due to the tension of the compression spring 510 being greater than the pressure of the medium, the piston rod 110 will return to its original position under the action of the tension of the compression spring 510. At this time, the high-pressure medium inlet 500 will close, and the high-pressure medium discharge port 700 will open. The medium will flow out through the high-pressure medium discharge port 700 to the high-pressure medium outlet hole 710, and finally be discharged to the drill bit on the right through the second water guiding hole 900 to cool the drill bit. Since the medium in the expansion sleeve 200 decreases, the expansion sleeve 200 will shrink, and at the same time the metal support plate 300 will retract.

[0033] In addition, it should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0034] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A pressure-controlled expansion type centralizing mechanism, comprising a centralizer body (100), the centralizer body (100) being cylindrical, characterized in that: An expansion sleeve (200) is sleeved outside the centralizer body (100), and both ends of the expansion sleeve (200) are fixed to the centralizer body (100). A plurality of metal support plates (300) are uniformly arranged on the outer side wall of the expansion sleeve (200). A rotating sleeve (400) is rotatably arranged inside the centralizer body (100). A plurality of high-pressure medium inlets (500) are arranged circumferentially on the outer side wall on the left side of the rotating sleeve (400). A high-pressure medium guiding hole (600) adapted to the high-pressure medium inlet (500) is formed on the outer side wall of the centralizer body (100). A plurality of high-pressure medium outlets (700) are arranged circumferentially on the outer side wall on the right side of the rotating sleeve (400). A high-pressure medium discharge hole (800) adapted to the high-pressure medium outlet (700) is arranged inside the rotating sleeve (400). A piston rod (110) is slidably arranged inside the rotating sleeve (400). Piston heads (210) are arranged at both ends of the piston rod (110). A left limit sleeve (310) is arranged on the left side of the left piston head (210). A sliding piston body (410) is arranged at the right end of the right piston head (210). A compression spring (510) is sleeved outside the sliding piston body (410). A right limit sleeve (610) is arranged on the right side of the sliding piston body (410); The axial cross-section of the sliding piston body (410) is cross-shaped. A first annular sealing ring (810) is arranged between the maximum diameter of the sliding piston body (410) and the inner side wall of the rotating sleeve (400). One end of the compression spring (510) is arranged on the right end face of the vertical part of the maximum diameter of the sliding piston body (410), and the other end of the compression spring (510) is arranged on the left side wall of the vertical part of the right limit sleeve (610). A high-pressure medium outlet hole (710) is arranged through the left side of the sliding piston body (410); A wear-resistant sleeve (910) is arranged outside the rotating sleeve (400) and inside the centralizer body (100).

2. The pressure-controlled expandable centralizing mechanism according to claim 1, characterized in that: A second annular sealing ring (120) is arranged on the outer side wall of the piston head (210).

3. The pressure control expansion type centralizing mechanism according to claim 2, characterized in that: Compression sleeves (220) for fixing the ends of the expansion sleeve (200) are arranged at both the left and right ends of the centralizer body (100).

4. The pressure-controlled expandable centralizing mechanism according to claim 3, characterized in that: An annular groove (320) is arranged on the inner side wall of the vertical part of the compression sleeve (220).

5. The pressure-controlled expandable centralizing mechanism according to claim 4, characterized in that: An expansion locking ring (420) is arranged in the annular groove (320) and on the outer side wall of the centralizer. Both ends of the expansion sleeve (200) are fixed to the outer side wall of the centralizer body (100) through the expansion locking ring (420). The outer side wall of the expansion sleeve (200) is in contact with the inner side wall of the expansion locking ring (420), and the outer side wall of the expansion locking ring (420) is in contact with the inner side wall of the annular groove (320).

6. The pressure-controlled expandable centralizing mechanism according to claim 5, characterized in that: The number of the metal support plates (300) is 8, and they are uniformly distributed on the axial outer side wall of the expansion sleeve (200).

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