Hydraulic remote control reducing eccentric reamer while drilling

Abstract

The utility model discloses a hydraulic remote control variable-diameter eccentric reamer while drilling, which comprises a body, and a plurality of reaming section radial holes are uniformly formed in the height direction and the circumferential direction of a middle reaming section; the periphery of the large-diameter end of the upper core shaft at the upper part is propped against the inner wall of the central hole of the body; the large-diameter end of the lower core shaft at the upper part is screwed with the lower end of the upper core shaft; the taper sleeves are stacked in multiple layers and fixed to the periphery of the upper mandrel, and taper sleeve slopes are symmetrically arranged on the peripheral wall of each taper sleeve; the reaming pistons are respectively positioned in the radial holes of the reaming sections, and the piston inclined surfaces of the inner ends of the reaming pistons are respectively connected with the inclined surfaces of the corresponding taper sleeves through dovetail grooves and dovetail tenons; the mandrel spring sleeves the periphery of the upper mandrel and is supported between the bottom of the large-diameter end of the upper mandrel and the taper sleeve; the periphery of the lower mandrel is sleeved with the controller, and a control guide groove is formed in the outer wall of the controller; and the inner end head of the control pin is embedded in the control guide groove. The telescopic state of the reaming piston can be adjusted through hydraulic remote control, the borehole treatment time is shortened, and the construction risk is reduced.

Description

Technical Field

[0001] The utility model relates to a drilling reamer, in particular to a hydraulic remote-controlled variable-diameter eccentric drilling reamer. The utility model utilizes a remote-controlled telescopic variable-diameter reaming piston based on the principle of a conventional eccentric stabilizer to improve the application efficiency of the eccentric reamer, and belongs to the technical field of drilling eccentric reaming. Background Art

[0002] Common reaming-while-drilling tools used in drilling operations include reamers and eccentric reamers. Reamers typically employ one or two sets of spiral blades slightly smaller than the wellbore diameter, mounted on the outer surface of the tool body. These blades scrape the wellbore while drilling, achieving micro-reaming while drilling. Eccentric reamers typically employ one or two sets of eccentrically positioned spiral blades mounted on the outer surface of the tool body. These blades utilize the uneven mass of the tool, generating lateral centrifugal force upon rotation, thereby expanding the wellbore to a larger diameter than the tool's outer diameter.

[0003] With the current trend of low-cost exploration and development, the proportion of long open holes and slim wells is increasing. The well sections of the same drilling are getting longer and longer. Due to the large differences in lithology and pressure systems of the upper and lower formations and the long construction period, the upper and lower wellbores of the same drilling have different shrinkage degrees. The wellbore processing time in the later stage of construction of the same drilling is relatively long. There is even the possibility of leakage formation due to poor annular space and high circulating pressure loss. The wellbore shrinkage is serious, resulting in abnormalities such as drill bit sticking and eye reamer.

[0004] The following problems exist in the actual reaming process of the drilling reamer and the eccentric drilling reamer:

[0005] 1. Reamers and eccentric reamers are generally placed in the drill pipe section of the drill string assembly and are larger than the drill string. They play a role in expanding the upper wellbore while drilling during drilling. However, since the construction time of the upper wellbore is longer than that of the newly drilled wellbore, the formation is prone to hydration and expansion due to the long soaking time. In addition, the blades are large in size, and mud cake and formation rock cuttings are easily wrapped around the reamer blades, which poses a risk of mud balling, reduces the annular fluid flow channel, and correspondingly increases the annular pressure loss.

[0006] 2. In the past, both reamers while drilling and eccentric reamers were equipped with fixed blades on the reamer body. If rapid drilling or annular passage needs to be improved due to downhole abnormalities, the circulation passage cannot be reduced due to the fixed blades of the reamer. In addition, rapid drilling may cause swabbing or high friction due to the presence of the fixed blades, inducing overflow and downhole collapse, making it difficult to achieve the purpose of rapid drilling. The adaptability to different wellbore conditions is poor.

[0007] 3. Generally, when drill bit is stuck and backturned underground, milling operation is required. If the reamer is buried below the backturn point, the outer diameter of the fixed blade is larger than the inner diameter of the milling barrel and the milling drill bit, especially the eccentric structure. The milling barrel cannot insert the reamer, and the milling operation cannot continue, making it difficult to salvage the drill tool. Utility Model Content

[0008] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and utility model title of this application, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0009] In view of the above problems and / or the problems existing in the prior art, the present utility model is proposed.

[0010] The purpose of the utility model is to overcome the problems existing in the prior art and provide a hydraulic remote-controlled variable diameter eccentric reamer while drilling, which is easy to operate and highly efficient. It can realize the hydraulic remote control adjustment of the telescopic state of the reaming piston according to different wellbore conditions during the downhole reaming operation, thereby reducing the wellbore processing time, reducing the construction risk, and improving the processing capability in complex fault conditions.

[0011] In order to solve the above technical problems, the utility model of the hydraulic remote control variable diameter eccentric drilling reamer comprises:

[0012] The main body has a reaming section in the middle, and multiple reaming section radial holes are evenly arranged along the height and circumference of the reaming section;

[0013] An upper core shaft is provided with an upper core shaft large diameter end at the upper portion, and the outer periphery of the upper core shaft large diameter end abuts against the upper inner wall of the central hole of the body;

[0014] The lower core shaft has a large diameter end provided on the upper portion thereof, and the center hole of the large diameter end of the lower core shaft is screwed to the lower end of the upper core shaft through a tapered female buckle;

[0015] Cone sleeves are stacked in multiple layers and fixed on the outer periphery of the upper core shaft, and the outer peripheral wall of each cone sleeve is symmetrically provided with a cone sleeve inclined surface;

[0016] The reaming pistons are located in the radial holes of the reaming sections, and the inner ends thereof are provided with piston slopes, and each piston slope is connected to the corresponding cone sleeve slope through a dovetail groove and a dovetail tenon;

[0017] A core shaft spring is sleeved on the outer periphery of the upper core shaft and supported between the bottom of the large diameter end of the upper core shaft and the uppermost tapered sleeve;

[0018] A controller is sleeved on the outer periphery of the lower core shaft, and a control guide groove is provided on the outer wall of the controller;

[0019] The control pin is screwed into the radial hole of the main body, and the inner end thereof is embedded in the control guide groove.

[0020] As an improvement of the present invention, a balancing piston is sleeved on the outer periphery of the middle portion of the lower core shaft, and the outer periphery of the balancing piston abuts against the inner wall of the body.

[0021] As a further improvement of the present invention, a pressure differential piston is provided below the balancing piston, the pressure differential piston is sleeved on the lower outer periphery of the lower core shaft, and a reducing groove is provided on the upper part of the pressure differential piston; a limit pin is embedded in the lower radial hole of the main body, and a limit pin through hole is provided along the axis of the limit pin, and the inner end of the limit pin is embedded in the reducing groove.

[0022] As a further improvement of the present invention, a throttle cone coaxial with the lower core shaft is provided below the lower core shaft, and the outer periphery of the throttle cone is fixed to the lower inner wall of the body through a hollow bracket.

[0023] As a further improvement of the present invention, the control guide groove extends vertically, a through control pin center hole is provided along the axis of the control pin, and a transformer joint is provided at the outer end of the control pin center hole.

[0024] As a further improvement of the present invention, the bottom of the large diameter end of the upper core shaft is supported on thrust bearing 1, the bottom of thrust bearing 1 is supported on the top of the upper spring seat, the upper end of the core shaft spring is against the bottom of the upper spring seat, the lower end of the core shaft spring is supported on the lower spring seat, and the bottom of the lower spring seat is supported on the inner step of the body.

[0025] As a further improvement of the present invention, the top of the large diameter end of the lower core shaft abuts against the bottom of the bottom tapered sleeve, the bottom of the large diameter end of the lower core shaft is supported on thrust bearing 2, the bottom of thrust bearing 2 is supported on the top of the controller, the bottom of the controller is supported on the bottom ring through thrust bearing 3, the bottom of the bottom ring is supported on the locking ring, and the locking ring is fixed on the outer periphery of the lower core shaft.

[0026] As a further improvement of the present invention, the control guide groove is wavy and surrounds the outer circumference of the controller.

[0027] As a further improvement of the present invention, the dovetail heights on the inclined surface of the cone sleeve are different on the same cross section.

[0028] Compared with the existing technology, the present invention has achieved the following beneficial effects: 1. By utilizing the eccentric setting of the reaming piston of the reaming tool, a lateral centrifugal force is generated when the drill string rotates, and the wellbore is expanded to a larger outer diameter than when the eccentric reaming piston is extended, so as to adapt to different wellbore conditions and construction procedures, thereby further reducing the wellbore processing time, reducing construction risks, and improving the processing capability in complex fault situations;

[0029] 2. This hydraulic remote-controlled variable-diameter eccentric underdrilling reamer is equipped with a resettable mandrel structure inside the drill bit sub. It has a simple and reliable structure and stable performance. Compared with existing underreamers, its use does not bring other risks to drilling operations.

[0030] 3. This hydraulic remote-controlled variable diameter eccentric under-drilling reamer utilizes the effect of fluid flow to control the expansion and contraction of the reaming piston, thereby controlling the expansion and contraction of the eccentric blades. It is more adaptable to different wellbore conditions than existing underreamers.

[0031] 4. The hydraulic remote-controlled variable diameter eccentric drilling reamer has the same body size as conventional drilling tools. If an abnormality occurs and salvage is required, it will not affect the salvage operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. The drawings are only provided for reference and explanation, and are not intended to limit the present invention. Among them:

[0033] Figure 1 This is a structural diagram of the hydraulic remote-controlled variable-diameter eccentric drilling reamer of the utility model;

[0034] Figure 2 This is a cross-sectional view of a connection method between the inclined surface of the cone sleeve and the inclined surface of the piston in the utility model;

[0035] Figure 3 This is a perspective view of another embodiment of the cone sleeve in the present invention;

[0036] Figure 4 A perspective view of another embodiment of the reaming piston in the present invention;

[0037] In the figure: 1. Main body; 2. Upper core shaft; 3. Thrust bearing 1; 4. Upper spring seat; 5. Core shaft spring; 6. Lower spring seat; 7. Taper sleeve; 7a. Taper sleeve inclined surface; 7b. Dovetail groove; 8. Reaming piston; 8a. Piston inclined surface; 8b. Dovetail tenon; 9. Lower core shaft; 10. Thrust bearing 2; 11. Controller; 11a. Control guide groove; 12. Thrust bearing 3; 13. Bottom ring; 14. Locking ring; 15. Control pin; 16. Balance piston; 17. Pressure difference piston; 18. Limit pin; 19. Throttle cone. DETAILED DESCRIPTION

[0038] In the following description of the present invention, the terms "upper", "lower", "front", "back", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device must have a specific direction.

[0039] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below with reference to specific figures. Obviously, the embodiments described are only a part of the present invention, not all of the embodiments.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0041] like Figure 1 As shown, the hydraulic remote-controlled variable-diameter eccentric underdrilling reamer of the present invention includes a body 1, an upper mandrel 2, a mandrel spring 5, a taper sleeve 7, a reaming piston 8, a lower mandrel 9, a controller 11, a control pin 15, a balancing piston 16, a pressure differential piston 17, a limit pin 18, and a throttle cone 19. The upper end of the body 1 is provided with a drill pipe box connected to the upper drill pipe. The middle portion of the body 1 is provided with a reaming section, with multiple reaming section radial holes uniformly arranged along the height and circumference of the reaming section. The lower end of the body 1 is provided with a drill pipe pin connected to the lower drill pipe.

[0042] The upper and lower mandrels 2 and 9 are located in the center hole of the main body. The upper mandrel 2 is provided with a large-diameter upper mandrel end, the outer periphery of which abuts against the upper inner wall of the main body center hole. The lower mandrel 9 is provided with a large-diameter lower mandrel end. The center hole of the large-diameter lower mandrel end is screwed to the lower end of the upper mandrel 2 via a tapered female thread.

[0043] Multiple tapered sleeves 7 are stacked around the outer circumference of the upper mandrel 2, each positioned to correspond to the reaming section of the body 1. Each sleeve 7 is symmetrically provided with three or four tapered sleeve slopes 7a on its outer circumference, with the lower end of each sloped surface 7a tilted toward the body axis. The top sleeve rests against the lower outer step of the upper mandrel 2.

[0044] A reaming piston 8 is provided in the radial hole of each reaming section. The inner end of each reaming piston 8 is provided with a piston slope 8a. Each piston slope 8a corresponds to the corresponding tapered sleeve slope 7a and is connected to the dovetail tenon through a dovetail groove.

[0045] Figure 2The figure shows a first connection mode between the tapered sleeve inclined surface 7a and the piston inclined surface 8a. A dovetail groove is provided on the piston inclined surface, and a dovetail tenon is provided on the tapered sleeve inclined surface. The dovetail tenon is inserted into the dovetail groove. When the tapered sleeve moves downward, the reaming piston 8 is pushed outward along the radial hole of the reaming section through the cooperation of the dovetail groove and the dovetail tenon, so that the outer end of the reaming piston is exposed outside the body 1 to realize the reaming operation; the outer wall of each reaming piston is provided with cutting teeth to improve the cutting effect.

[0046] Figure 3 、 Figure 4 The figure shows a second connection mode between the tapered sleeve inclined surface 7a and the piston inclined surface 8a. A dovetail tenon 8b is provided on the piston inclined surface 8a, and a dovetail groove 7b is provided on the tapered sleeve inclined surface 7a. The dovetail tenon 8b is still inserted in the dovetail groove 7b.

[0047] When pressure builds up in the center hole of the body, the central fluid pushes the upper mandrel 2 downward, overcoming the tension of the mandrel spring 5. The upper mandrel 2 pushes the tapered sleeves downward, and each tapered sleeve squeezes out the reaming pistons 8 on the outer periphery. When pressure is relieved from the center hole of the body, the tension of the mandrel spring 5 pushes the large-diameter end of the upper mandrel upward, and the upper mandrel 2 and each tapered sleeve move upward synchronously, pulling the reaming pistons 8 radially back.

[0048] The bottom of the large diameter end of the upper core shaft is supported on the thrust bearing 3, the bottom of the thrust bearing 3 is supported on the top of the upper spring seat 4, the core shaft spring 5 is sleeved on the outer periphery of the upper core shaft 2, the upper end of the core shaft spring 5 is against the bottom of the upper spring seat 4, the lower end of the core shaft spring 5 is supported on the lower spring seat 6, and the bottom of the lower spring seat 6 is supported on the inner step of the main body and is located above the uppermost tapered sleeve.

[0049] The top of the large diameter end of the lower core shaft rests against the bottom of the bottom tapered sleeve, and the bottom of the large diameter end of the lower core shaft is supported on the thrust bearing 2 10. The bottom of the thrust bearing 2 10 is supported on the top of the controller 11. The controller 11 is sleeved on the outer periphery of the lower core shaft 9. The bottom of the controller 11 is supported on the bottom ring 13 through the thrust bearing 3 12. The bottom of the bottom ring 13 is supported on the locking ring, and the locking ring is fixed to the outer periphery of the lower core shaft 9.

[0050] The outer wall of the controller 11 is provided with a control guide groove 11a. A control pin 15 is threaded into a radial hole in the body. The inner end of the control pin 15 engages in the control guide groove 11a of the controller 11 to control the raising and lowering of the controller 11. When the control pin 15 slides relative to the top of the control guide groove 11a, the controller 11 reaches the lower limit position, at which point the reaming pistons 8 extend to their maximum position. When the control pin 15 slides relative to the bottom of the control guide groove 11a, the controller 11 reaches the upper limit position, at which point the reaming pistons 8 fully retract, preventing the tool from scraping against the wellbore wall during raising and lowering.

[0051] The first design of the control channel 11a extends vertically, with a central bore extending through the axis of the control pin 15. A pressure-transformer connector is installed at the outer end of the central bore. Fluid flow from the annulus of the main body is regulated by the pressure-transformer connector and enters the control channel 11a, providing an upward reaction force for the controller 11. When the pressure at the outer periphery of the main body exceeds the pressure at the central bore, the larger diameter end of the lower mandrel is lifted upward, simultaneously with the upward movement of the upper mandrel 2. The pressure-transformer connector adjusts the opening of the outer port of the control pin's central bore, achieving a certain degree of pressure reduction.

[0052] The second design for the control guide groove 11a is a wavy shape that surrounds the outer circumference of the controller 11. In this case, the annular space of the main body does not need to be pressurized. Each time the central hole of the main body is pressurized, the controller 11 slides downward. After the pressure is released, the controller 11 slides upward. Each time the controller 11 slides, it rotates a certain angle, and this cycle repeats.

[0053] The dovetail heights on the tapered sleeve inclined surface 7a on the same cross section are different, so that the extension strokes of the reaming pistons 8 on the outer periphery of the tapered sleeve are different. After the reaming pistons 8 are extended, the rotational outer diameters in each direction are different. When rotating, due to the uneven mass, a lateral centrifugal force is generated, resulting in an eccentric effect, which can ream a wellbore size larger than the outer diameter after the reaming pistons are extended.

[0054] A balancing piston 16 is mounted on the outer periphery of the middle portion of the lower core shaft 9. The outer periphery of the balancing piston 16 abuts against the inner wall of the body, which plays a role in straightening. When the core shaft moves downward, the balancing piston 16 can float downward to avoid pressure buildup above the balancing piston 16.

[0055] Below the balancing piston 16 is a differential pressure piston 17, which is fitted around the lower periphery of the lower core shaft 9. A reduced-diameter groove is located on its upper portion. A limit pin 18 is embedded in a radial hole in the lower portion of the body. A limit pin through-hole is provided along the axis of the limit pin 18, with the inner end of the limit pin 18 embedded in the reduced-diameter groove. The differential pressure piston 17 can float up and down within a certain range. When the pressure above is too high, it can release pressure to the annulus through the limit pin through-hole.

[0056] A throttle cone 19 is coaxially mounted below the lower mandrel 9. Its outer periphery is secured to the lower inner wall of the main body via a hollow bracket. As the lower mandrel 9 descends, the upper end of the throttle cone 19 enters the center hole of the lower mandrel, creating a pressure buildup in the central flow. This causes the pump pressure at the wellhead to fluctuate, signaling that the reaming piston has been extended.

[0057] This tool utilizes an internal axially positioned mandrel structure, which drives retractable reaming pistons via a tapered sleeve. Fluid flow controls the downward movement of the mandrel, while the pistons remain stationary axially. As the tapered sleeve descends, its inclined surface propels the pistons radially through dovetail grooves. Due to the varying strokes of the reaming pistons in different circumferential directions, the extended pistons rotate at different outer diameters. As the drill string rotates, the uneven mass of the tool generates lateral centrifugal force, creating an eccentric reaming effect that cuts and scrapes the wellbore wall, achieving reaming-while-drilling.

[0058] When the pump is stopped and there is no liquid flow, the core shaft spring 5 pushes the core shaft upward to reset, and then drives the cone sleeve upward, and the reaming piston retracts. After retraction, the reaming piston is flush with the outer surface of the body. During the drilling process, there will be no abnormal phenomena such as hanging and pulling on the well wall, causing the reamer to be mud-packed, thereby increasing friction and pulling out the piston.

[0059] The extension length, inner diameter, outer diameter and extension length of the main body and reaming piston are designed and adjusted according to the actual size of the wellbore on site.

[0060] Engineering Case 1: If drilling is carried out in a Φ215.9mm wellbore, the main body is selected to be Φ165mm in size, and the reaming piston is designed to be Φ215.9mm in the extended state. During drilling, due to the pump being turned on and the drill string rotating, the hydraulic remote-controlled variable diameter eccentric reamer generates lateral centrifugal force due to its eccentric structure, and the maximum theoretical diameter can be expanded to Φ226mm. After the single rod or column is drilled, the pump is stopped and the reaming piston retracts, which does not increase the friction resistance of drilling and does not cause mud packing to reduce the annular space channel.

[0061] Engineering Case 2: When drilling in a Φ311.1mm wellbore, the main body is Φ203mm in size, and the reaming piston is designed to be Φ311.1mm in the extended position. During drilling, due to the pump being turned on and the drill string rotating, the hydraulic remote-controlled variable diameter eccentric reamer generates lateral centrifugal force due to its eccentric structure, and the maximum theoretical diameter can be expanded to Φ321mm. Similarly, after the single rod or column is drilled and the pump is stopped, the reaming piston retracts, without adding additional friction during tripping or causing mud packing that reduces the annular passage, allowing for rapid drilling.

[0062] The above description is only a preferred embodiment of the present invention, which shows and describes the basic principles, main features and advantages of the present invention, but does not limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. In addition to the above embodiments, the present invention may have other implementation methods without departing from the spirit and scope of the present invention. The present invention may also have various changes and improvements, and all technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents. Technical features not described in the present invention can be achieved by or using existing technologies, and will not be described here.

Claims

1. A hydraulic remote-controlled variable diameter eccentric reamer, characterized in that: include: The main body has a reaming section in the middle, and multiple reaming section radial holes are evenly arranged along the height and circumference of the reaming section; An upper core shaft is provided with an upper core shaft large diameter end at the upper portion, and the outer periphery of the upper core shaft large diameter end abuts against the upper inner wall of the central hole of the body; The lower core shaft has a large diameter end provided on the upper portion thereof, and the center hole of the large diameter end of the lower core shaft is screwed to the lower end of the upper core shaft through a tapered female buckle; Cone sleeves are stacked in multiple layers and fixed on the outer periphery of the upper core shaft, and the outer peripheral wall of each cone sleeve is symmetrically provided with a cone sleeve inclined surface; The reaming pistons are located in the radial holes of the reaming sections, and the inner ends thereof are provided with piston slopes, and each piston slope is connected to the corresponding cone sleeve slope through a dovetail groove and a dovetail tenon; A core shaft spring is sleeved on the outer periphery of the upper core shaft and supported between the bottom of the large diameter end of the upper core shaft and the uppermost tapered sleeve; A controller is sleeved on the outer periphery of the lower core shaft, and a control guide groove is provided on the outer wall of the controller; The control pin is screwed into the radial hole of the main body, and the inner end thereof is embedded in the control guide groove.

2. The hydraulic remote-controlled variable diameter eccentric reamer while drilling according to claim 1, characterized in that: A balancing piston is sleeved on the outer periphery of the middle portion of the lower core shaft, and the outer periphery of the balancing piston abuts against the inner wall of the body.

3. The hydraulic remote-controlled variable diameter eccentric underdrilling reamer according to claim 2, characterized in that: A pressure differential piston is provided below the balancing piston, and the pressure differential piston is sleeved on the lower outer periphery of the lower core shaft. A reducing groove is provided on the upper part of the pressure differential piston; a limit pin is embedded in the lower radial hole of the main body, and a limit pin through hole is provided along the axis of the limit pin, and the inner end of the limit pin is embedded in the reducing groove.

4. The hydraulic remote-controlled variable diameter eccentric underdrilling reamer according to claim 1, characterized in that: A throttling cone coaxial with the lower core shaft is provided below the lower core shaft, and the outer periphery of the throttling cone is fixed to the lower inner wall of the body through a hollow bracket.

5. The hydraulic remote-controlled variable diameter eccentric underdrilling reamer according to claim 1, characterized in that: The control guide groove extends vertically, and a penetrating control pin center hole is provided along the axis of the control pin. The outer end of the control pin center hole is provided with a voltage transformer joint.

6. The hydraulic remote-controlled variable diameter eccentric underdrilling reamer according to claim 1, characterized in that: The bottom of the large diameter end of the upper core shaft is supported on the thrust bearing 1, the bottom of the thrust bearing 1 is supported on the top of the upper spring seat, the upper end of the core shaft spring is against the bottom of the upper spring seat, the lower end of the core shaft spring is supported on the lower spring seat, and the bottom of the lower spring seat is supported on the inner step of the body.

7. The hydraulic remote-controlled variable diameter eccentric underdrilling reamer according to claim 1, characterized in that: The top of the large diameter end of the lower core shaft rests against the bottom of the bottom tapered sleeve, the bottom of the large diameter end of the lower core shaft is supported on thrust bearing 2, the bottom of thrust bearing 2 is supported on the top of the controller, the bottom of the controller is supported on the bottom ring through thrust bearing 3, the bottom of the bottom ring is supported on the locking ring, and the locking ring is fixed on the outer periphery of the lower core shaft.

8. The hydraulic remote-controlled variable diameter eccentric underdrilling reamer according to any one of claims 1 to 4, characterized in that: The control guide groove is wave-shaped and surrounds the outer periphery of the controller.

9. The hydraulic remote-controlled variable diameter eccentric underdrilling reamer according to any one of claims 1 to 7, characterized in that: The dovetail heights on the tapered sleeve inclined surface on the same cross section are different, and the outer wall of each reaming piston is respectively provided with cutting teeth.

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