A retractable blade PDC bit

Abstract

The present application belongs to the technical field of drilling equipment, and particularly relates to a telescopic blade PDC drill bit. The telescopic blade PDC drill bit comprises an outer cylinder, at least one fixed blade fixedly arranged at the end of the outer cylinder, at least one movable blade slidingly arranged at the end of the outer cylinder in the axial direction, and a telescopic mechanism arranged in the outer cylinder and connected with the movable blade, the telescopic mechanism being arranged to be capable of controlling the movable blade to axially telescope in response to the pressure of drilling fluid, so that the movable blade is in a working state or a non-working state. The present application can change the number of blades, so as to adapt to the stratum with large lithology change.

Description

Technical Field

[0001] This invention belongs to the field of drilling equipment technology, specifically, it relates to a telescopic blade PDC drill bit. Background Technology

[0002] Drill bits are a major component of drilling equipment. Their main function is to break rocks and form wellbores. They are used in the oil and gas, geological exploration, and drilling industries.

[0003] PDC drill bits are tools that use polycrystalline diamond composite blades as cutting elements to break rocks through scraping. Conventional PDC drill bits have fixed blades, and the number of blades on the bit is determined by the formation conditions. In other words, different formations often require drill bits with different numbers and structures of blades to maximize drilling efficiency. PDC drill bits suitable for hard, difficult-to-drill formations have more blades, allowing for more cutting teeth and increasing the drill bit's lifespan in these formations; however, this reduces the drill bit's ability to penetrate the formation. PDC drill bits suitable for medium-soft formations can improve their penetration ability and rock-breaking efficiency by reducing the tooth density, but this negatively impacts their lifespan. When encountering formations with significant lithological variations during drilling, a single drill bit's blade number and cutting structure cannot simultaneously match multiple formations. In this case, neither drill bit lifespan nor rock-breaking efficiency can be guaranteed, requiring frequent tripping and bit replacement, which undoubtedly prolongs the drilling cycle and increases drilling costs. Therefore, traditional PDC drill bits have difficulty simultaneously improving both mechanical drilling speed and drill bit life in heterogeneous formations, and they are poorly adaptable to formations with significant lithological variations. Summary of the Invention

[0004] To address the technical problems described above, this invention aims to provide a telescopic blade PDC drill bit, which can change the number of blades to adapt to formations with significant lithological variations.

[0005] According to the present invention, a telescopic blade PDC drill bit is provided, comprising:

[0006] outer cylinder;

[0007] At least one fixed blade is fixedly installed at the end of the outer cylinder;

[0008] At least one movable blade is slidably disposed at the end of the outer cylinder along the axial direction;

[0009] And a telescopic mechanism disposed inside the outer cylinder, the telescopic mechanism being connected to the movable cutter blade, the telescopic mechanism being configured to respond to the pressure of the drilling fluid and control the movable cutter blade to extend and retract axially, thereby putting the movable cutter blade into a working state or a non-working state.

[0010] In one specific embodiment, the telescopic mechanism comprises a core pipe coaxially slidingly arranged in the outer cylinder, one end of the core pipe being fixedly connected with the movable blade.

[0011] In one specific embodiment, the telescopic mechanism further comprises:

[0012] a resilient member, axial ends of the resilient member being connected with the core pipe and the outer cylinder respectively;

[0013] a slip ring shaft, the slip ring shaft being circumferentially rotatably arranged in the outer cylinder;

[0014] a grooved wheel assembly, the grooved wheel assembly being coaxially fixed on the core pipe, the grooved wheel assembly being adapted with the slip ring shaft,

[0015] a differential pressure surface being arranged at the end of the core pipe for responding to the pressure of the drilling fluid.

[0016] In one specific embodiment, the grooved wheel assembly comprises an upper grooved wheel and a lower grooved wheel fixedly connected coaxially, a plurality of first slopes being uniformly arranged circumferentially at the lower end of the upper grooved wheel, a plurality of second slopes being uniformly arranged circumferentially at the upper end of the lower grooved wheel, a low-position groove and a high-position groove being arranged at both ends of the second slope respectively, the low-position groove and the high-position groove corresponding to two adjacent first slopes respectively.

[0017] In one specific embodiment, a sliding ring is coaxially rotatably arranged on the inner wall of the outer cylinder, at least one of the slip ring shafts being arranged on the inner wall of the sliding ring, the central axis of the slip ring shaft coinciding with the diameter of the sliding ring.

[0018] In one specific embodiment, the slip ring shaft is rotatably connected with the sliding ring through a bearing.

[0019] In one specific embodiment, in the working state of the movable blade, the height difference between the movable blade and the working end face of the fixed blade is zero, and in the non-working state of the movable blade, the height difference between the movable blade and the working end face of the fixed blade is 0-5 mm.

[0020] In one specific embodiment, the movable blade is fixedly connected with the core pipe through a pin shaft, a pin hole being arranged radially on the outer wall of the core pipe, a through hole being arranged radially on the movable blade, the pin shaft being arranged in the pin hole and the through hole.

[0021] In one specific embodiment, the outer cylinder comprises:

[0022] an outer housing;

[0023] an upper joint arranged at the upper end of the outer housing;

[0024] and a lower joint arranged at the lower end of the outer housing;

[0025] Wherein, the axial two ends of the elastic member respectively abut against the core pipe and the lower joint, and the sliding ring shaft is arranged between the upper joint and the outer housing.

[0026] In one specific embodiment, a drill bit body is fixedly arranged at the end of the lower joint away from the outer housing, the fixed blade wing is fixedly arranged on the drill bit body, and the movable blade wing is arranged in an axial sealing sliding manner on the drill bit body.

[0027] Compared with the prior art, the application has the following advantages.

[0028] The application is provided with a fixed blade wing, a movable blade wing and a telescopic mechanism, which can drive the movable blade wing to axially telescope in response to the pressure of the drilling fluid, so as to realize the downhole adjustment of the number of drill bit blade wings according to the change of drilled strata, and overcome the poor stratum adaptability of the existing fixed blade wing drill bit. The telescopic mechanism can make the movable blade wing axially extend outward in response to the pressure of the drilling fluid when facing hard strata, so that the movable blade wing and the fixed blade wing jointly perform drilling work at this time, the number of blade wings is more, more cutting teeth can be arranged, and the service life of the drill bit in hard and difficult-to-drill strata can be improved; the telescopic mechanism can make the movable blade wing axially retract inward in response to the pressure of the drilling fluid when facing medium-soft strata, so that only the fixed blade wing performs drilling work at this time, the number of blade wings is less, the ability of the drill bit to cut into the strata can be improved, and the rock breaking efficiency can be improved.

[0029] The relative height difference of the fixed blade wing and the movable blade wing can be changed according to the design parameters of the groove wheel assembly, so as to prolong the service life of the drill bit while ensuring the rock breaking efficiency of the drill bit. BRIEF DESCRIPTION OF DRAWINGS

[0030] The application will be described below with reference to the drawings.

[0031] Figure 1 shows the external structure schematic diagram of one embodiment of the telescopic blade wing PDC drill bit according to the application;

[0032] Figure 2 shows the sectional view of one embodiment of the telescopic blade wing PDC drill bit according to the application;

[0033] Figure 3 shows the schematic diagram of the core pipe according to the application;

[0034] Figure 4 shows the schematic diagram of the groove wheel assembly according to the application;

[0035] Figure 5A schematic view of a sliding ring according to the present application is shown.

[0036] Figure 6 A schematic view of a deployment of a sheave assembly according to the present application is shown.

[0037] Figures 7-11 A schematic view of different positions of the sheave assembly working with the sliding ring shaft is shown.

[0038] Figure 12 A schematic view of a movable blade according to the present application is shown.

[0039] In the figure: 20, outer barrel; 30, telescopic mechanism; 1, upper joint; 2, sliding ring; 3, bearing; 4, sliding ring shaft; 5, outer housing; 6, elastic member; 7, lower joint; 8, pin shaft; 9, sheave assembly; 91, upper sheave; 92, lower sheave; 910, first slope; 920, second slope; 921, low position groove; 922, high position groove; 10, cutting tooth; 11, movable blade; 12, nozzle; 13, fixed blade; 14, core pipe; 140, pin hole; 141, differential pressure surface; 142, small diameter part; 143, large diameter part; 15, liquid flow channel; 110, drill bit body; 111, through hole; 1101, central axis; 100, telescopic blade PDC drill bit.

[0040] In the present application, all the drawings are schematic drawings, only for illustrating the principles of the present application, and are not drawn in actual proportion. DETAILED DESCRIPTION

[0041] The present application will be described below by means of the drawings.

[0042] It should be noted that in the present application, the direction provided with the fixed blade 13 according to the present application is described as "down" or similar terms, i.e. Figure 1 the right side of ; and the end provided with the upper joint 1 is described as "up" or similar terms, i.e. Figure 1 the left side of .

[0043] Figure 1 A structure of a telescopic blade PDC drill bit 100 according to the present application is shown. As shown in Figure 1 and Figure 2 , the telescopic blade PDC drill bit 100 comprises an outer barrel 20, a fixed blade 13, a movable blade 11 and a telescopic mechanism 30.

[0044] At least one fixed blade 13 is fixedly arranged at the lower end of the outer barrel 20, and at least one movable blade 11 is slidingly arranged.

[0045] The telescopic mechanism 30 is arranged inside the outer cylinder 20, specifically, the telescopic mechanism 30 is arranged in the liquid flow channel 15 inside the outer cylinder 20, and the lower end of the telescopic mechanism 30 is connected with the movable blade wing 11. The telescopic mechanism 30 is arranged to be able to control the telescopic movement of the movable blade wing 11 along the axial direction in response to the pressure of the drilling fluid, so as to make the movable blade wing 11 in the working state or the non-working state.

[0046] In a specific embodiment, the outer cylinder 20 comprises an upper joint 1, an outer shell 5, a lower joint 7 and a drill bit body 110 which are coaxially and fixedly connected from top to bottom.

[0047] An external thread is arranged at the upper end of the upper joint 1 for connecting with other downhole tools. An internal thread is arranged at the lower end of the upper joint 1, and an internal thread is arranged at the upper end of the outer shell 5. The upper joint 1 and the outer shell 5 are fixedly connected through the threads. An internal thread is arranged at the lower end of the outer shell 5, and an external thread is arranged at the upper end of the lower joint 7. The outer shell 5 and the lower joint 7 are fixedly connected through the threads. The drill bit body 110 is fixedly arranged at the lower end of the lower joint 7.

[0048] A nozzle 12 is arranged at the lower end of the drill bit body 110, which is communicated with the liquid flow channel 15. The drilling fluid can flow to the outside of the telescopic blade wing PDC drill bit 100 through the liquid flow channel 15 and the nozzle 12.

[0049] A plurality of fixed blade wings 13 are uniformly arranged at the lower end of the drill bit body 110 in the circumferential direction, and a plurality of cutting teeth 10 are arranged on the fixed blade wings 13. A plurality of movable blade wings 11 are uniformly arranged on the drill bit body 110 in the circumferential direction, and a plurality of cutting teeth 10 are arranged on the movable blade wings 11. Each movable blade wing 11 is arranged on the drill bit body 110 in a sealing sliding connection along the direction of the central axis, and the movable blade wing 11 is fixedly connected with the telescopic mechanism 30. The tooth profile of the fixed blade wing 13 and the movable blade wing 11 and the cutting teeth 10 arranged thereon can be designed according to the blade wing in the prior art.

[0050] In a preferred embodiment, the cutting teeth 10 arranged on the movable blade wing 11 and the fixed blade wing 13 are PDC teeth, rotary cutting teeth, buffer teeth, roller teeth or a combination of several kinds of cutting teeth, which can cope with different formation conditions.

[0051] In a preferred embodiment, a baffle (not shown in the figure) for restraining the circumferential deformation of the movable blade wing 11 is arranged on the drill bit body 110, and the number of the baffles is the same as the number of the movable blade wings 11.

[0052] In the present application, as Figures 1-3 and Figure 12As shown, the telescopic mechanism 30 comprises a core pipe 14 coaxially slidingly arranged in the outer cylinder 20, and the lower end of the core pipe 14 is fixedly connected with the movable blade 11. At least one through hole 111 is arranged on the movable blade 11 in the radial direction, and a pin hole 140 corresponding to the through hole 111 is arranged on the core pipe 14. When the movable blade 11 and the core pipe 14 are fixed to each other, the lower end surface of the movable blade 11 axially abuts against the lower end of the core pipe 14, the through hole 111 of the movable blade 11 coincides with the axis of the pin hole 140 of the core pipe 14, the pin shaft 8 enters from the outside of the movable blade 11 along the through hole 111 inwardly, and finally enters the pin hole 140 of the core pipe 14, and a part of the length of the pin shaft 8 is located in the pin hole 140, and the other part of the length of the pin shaft 8 is located in the through hole 111.

[0053] In order to enhance the connection strength of the core pipe 14 and the movable blade 11, a plurality of pin holes 140 and through holes 111 can be arranged.

[0054] Specifically, the core pipe 14 comprises a large-diameter part 143 and a small-diameter part 142 which are coaxially fixedly connected. The inner diameters of the small-diameter part 142 and the large-diameter part 143 are equal, and the outer diameter of the large-diameter part 143 is larger than the outer diameter of the small-diameter part 142.

[0055] The upper end of the lower joint 7 extends to the inside of the outer housing 5, that is, the upper end of the lower joint 7 has an inner diameter smaller than the inner diameter of the lower end of the outer housing 5. The outer wall of the large-diameter part 143 is in contact with the inner wall of the outer housing 5, and the outer wall of the small-diameter part 142 is in contact with the inner wall of the lower joint 7.

[0056] An annular space is formed between the large-diameter part 143, the small-diameter part 142, the lower joint 7 and the outer housing 5, and the elastic member 6 is arranged in the annular space. Specifically, the elastic member 6 is coaxially sleeved on the small-diameter part 142, and the axially opposite ends of the elastic member 6 abut against the large-diameter part 143 and the lower joint 7, respectively.

[0057] In one specific embodiment, the elastic member 6 can adopt any one of a spring, a disc spring and rubber.

[0058] When the movable blade 11 is in a non-working state, the upper end of the core pipe 14 axially abuts against the upper joint 1 under the action of the force of the elastic member 6, and at the same time, the upper end of the movable blade 11 axially abuts against the lower joint 7, that is, the position relationship shown. Figure 2 Preferably, at this time, the height difference between the working end surfaces of the movable blade 11 and the fixed blade 13 is 0-5 mm, that is, the lowermost end of the movable blade 11 is higher than the lowermost end of the fixed blade 13, and the height difference between the lowermost end of the movable blade 11 and the lowermost end of the fixed blade 13 is greater than zero and less than 5 mm, at this time, only the fixed blade 13 participates in rock breaking work, and drilling is carried out.

[0059] When the movable blade 11 is in working state, the height difference between the working end face of the movable blade 11 and the fixed blade 13 is zero, at this time, the movable blade 11 and the fixed blade 13 jointly drill the stratum.

[0060] According to the present application, as Figure 2 shown, the slip ring shaft 4 is coaxially arranged on the inner wall of the outer cylinder 20, and the groove wheel assembly 9 is coaxially fixed on the core pipe 14 and matched with the slip ring shaft 4. The groove wheel assembly 9 can be fixed with the core pipe 14 by integral molding, or can be separately processed and then fixedly connected.

[0061] Specifically, as Figure 4 shown, the groove wheel assembly 9 includes the upper groove wheel 91 and the lower groove wheel 92 which are coaxially fixedly connected, a plurality of first slopes 910 are uniformly arranged on the lower end of the upper groove wheel 91 in the circumferential direction, a plurality of second slopes 920 are uniformly arranged on the upper end of the lower groove wheel 92 in the circumferential direction, and the inclination directions of the first slopes 910 and the second slopes 920 are opposite. A space for accommodating the slip ring shaft 4 is left between the first slopes 910 and the second slopes 920, and the movement track of the slip ring shaft 4 between the first slopes 910 and the second slopes 920 is as Figures 7-11 shown, which will be described in detail below.

[0062] As Figure 4 and Figure 6 shown, the low-position groove 921 and the high-position groove 922 are respectively arranged at both ends of each second slope 920, that is, the low-position grooves 921 and the high-position grooves 922 are alternately arranged in sequence. At the same time, the low-position grooves 921 and the high-position grooves 922 correspond to the inclined surfaces of the adjacent two first slopes 910 respectively.

[0063] In combination with Figure 2 and Figures 7-11 , the working principle of the groove wheel assembly 9 and the slip ring shaft 4 is as follows.

[0064] Figure 2 The core pipe 14 and the movable blade 11 in the state of contraction, that is, the movable blade 11 is in a non-working state, at this time, the position relationship between the groove wheel assembly 9 and the slip ring shaft 4 is as Figure 7 shown, the slip ring shaft 4 is located in the low-position groove 921.

[0065] When it is needed to extend the movable blade 11, that is, the movable blade 11 works together with the fixed blade 13, the pressure of the drilling fluid in the flow channel 15 is increased, and the core pipe 14 moves downward relative to the outer cylinder 20 in response to the pressure of the drilling fluid to compress the elastic member 6. Since the core pipe 14 is fixedly connected with the groove wheel assembly 9, and the slip ring shaft 4 is axially fixed and axially rotatable relative to the outer cylinder 20, at this time, the groove wheel assembly 9 moves along Figure 7the arrow direction in the figure moves downward relative to the slip ring shaft 4, and moves to the abutment of the slip ring shaft 4 and the first slope 910, as shown in Figure 8 .

[0066] The sheave assembly 9 continues to move downward, at this time, the slip ring shaft 4 rotates in the circumferential direction under the action of the slope of the first slope 910, that is, the slip ring shaft 4 moves to the right in the figure, until the slip ring shaft 4 moves to between the adjacent two first slopes 910, as shown in Figure 9 . Figure 9

[0067] Then, the drilling fluid pressure in the flow passage 15 is lowered, the core tube 14 starts to reset upward under the action of the elastic member 6, at the same time, the sheave assembly 9 also moves upward, as shown in Figure 10 , the sheave assembly 9 moves upward relative to the slip ring shaft 4 along the arrow direction in the figure, until the slip ring shaft 4 contacts the second slope 920.

[0068] The sheave assembly 9 moves upward, at this time, the slip ring shaft 4 rotates in the circumferential direction under the action of the slope of the second slope 920, that is, the slip ring shaft 4 moves to the right in the figure, until the slip ring shaft 4 moves to the high-position groove 922. At this time, the core tube 14 drives the movable blade 11 to move downward to be flush with the fixed blade 13, and the movable blade 11 is fixed. Figure 11

[0069] When it is needed to retract the movable blade 11, that is, only the fixed blade 13 is needed to work, the drilling fluid pressure in the flow passage 15 is again raised and lowered in sequence, and the similar operation process is repeated, so that the slip ring shaft 4 is located in the low-position groove 921.

[0070] The above process is repeated, since the sheave assembly 9 is connected with the core tube 14, and the core tube 14 is connected with the movable blade 11, thus, the position change of the core tube 14 and the sheave assembly 9 can realize the free switching of the extended and retracted states of the movable blade 11.

[0071] By setting the height difference between the high-position groove 922 and the low-position groove 921, the height difference between the movable blade 11 and the fixed blade 13 in the non-working state can be controlled.

[0072] In a preferred embodiment, in order to enable the movable blade 11 to have different extension amounts to realize different relative working heights of the movable blade 11 and the fixed blade 13, the lower sheave 92 can be provided with multiple sets of different limit positions (sets of high-position grooves 922 and low-position grooves 921 with different height differences), preferably 1-3 sets.

[0073] In a specific embodiment, in order to enable the core tube 14 to respond to the pressure of the drilling fluid, as shown in Figure 2 ​​As shown in the figure, a differential pressure surface 141 is arranged at the upper end of the core pipe 14 to respond to the pressure of the drilling fluid. The pressure receiving area of the upper end of the core pipe 14 is larger than that of the lower end, so when the core pipe 14 is in a pressure environment, the pressure difference between the upper and lower ends of the core pipe 14 is greater than the elastic force of the elastic member 6, and the core pipe 14 can overcome the force of the elastic member 6 and move downward.

[0074] In a preferred embodiment, as shown in the figure, Figure 2 and Figure 5 As shown in the figure, the sliding ring 2 is arranged coaxially on the inner wall of the outer cylinder 20, and at least one sliding ring shaft 4 is arranged on the inner wall of the sliding ring 2, and the central axis of the sliding ring shaft 4 coincides with the diameter of the sliding ring 2. In this embodiment, three sliding ring shafts 4 are uniformly arranged on the inner wall of the sliding ring 2 in the circumferential direction, so that the sliding ring shaft 4 is more stable when matched with the groove wheel assembly 9.

[0075] The sliding ring shaft 4 and the sliding ring 2 can be integrally formed, or the sliding ring shaft 4 and the sliding ring 2 can be connected by welding or interference fit.

[0076] It is easy to understand that although three sliding ring shafts 4 are arranged in this embodiment, the present application is not limited to arranging three sliding ring shafts 4, and those skilled in the art can change the number of sliding ring shafts 4 according to the present application in combination with the actual situation. It is easy to understand that the number of the first slope 910 and the second slope 920 of the groove wheel assembly 9 also changes according to the number of the sliding ring shaft 4. Such changes should be within the scope of the present application.

[0077] In a preferred embodiment, as shown in the figure, Figure 2 The sliding ring shaft 4 is rotatably connected to the sliding ring 2 through the bearing 3. The rotation axis of the sliding ring shaft 4 coincides with the diameter of the sliding ring 2. In this arrangement, when the sliding ring shaft 4 moves along the first slope 910 and the second slope 920, the friction between them can be reduced.

[0078] In a preferred embodiment, the sliding ring shaft 4 and the sliding ring 2 are arranged between the connection gap of the upper joint 1 and the outer shell 5. Specifically, in this embodiment, as shown in the figure, Figure 2 The upper end of the sliding ring 2 is in contact with the upper joint 1, the lower end of the sliding ring 2 is in contact with the outer shell 5, and the outer wall of the sliding ring 2 is in contact with the upper joint 1. Through this arrangement, the installation and disassembly of the sliding ring 2 can be facilitated.

[0079] In the description of the present application, it should be understood that the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0080] In this application, unless otherwise clearly indicated and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be interpreted broadly, for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0081] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0082] Finally, it should be pointed out that the above description is only the preferred embodiments of the present application and does not constitute any limitation on the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or replace some technical features with equivalent ones. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A telescopic blade PDC drill bit, characterized in that, include: outer cylinder (20); At least one fixed blade (13) is fixedly disposed at the end of the outer cylinder (20); At least one movable blade (11) is slidably disposed at the end of the outer cylinder (20) along the axial direction; And a telescopic mechanism (30) is provided inside the outer cylinder (20), the telescopic mechanism (30) is connected to the movable cutter wing (11), the telescopic mechanism (30) is configured to respond to the pressure of the drilling fluid and control the movable cutter wing (11) to extend and retract axially, thereby putting the movable cutter wing (11) into a working state or a non-working state. The telescopic mechanism (30) includes a core tube (14), an elastic element (6), a slip ring shaft (4), and a grooved wheel assembly (9). The core tube (14) is coaxially and slidably disposed inside the outer cylinder (20). One end of the core tube (14) is fixedly connected to the movable cutter blade (11). A differential pressure surface (141) for responding to drilling hydraulic pressure is provided at the end of the core tube (14). The two axial ends of the elastic element (6) are respectively connected to the core tube (14) and the outer cylinder (20). The slip ring shaft (4) is rotatably disposed inside the outer cylinder (20) in a circumferential manner. The grooved wheel assembly (9) is coaxially fixed to the outer cylinder. On the core tube (14), the grooved wheel assembly (9) is adapted to the slip ring shaft (4). The grooved wheel assembly (9) includes an upper grooved wheel (91) and a lower grooved wheel (92) that are coaxially fixedly connected. Multiple first ramps (910) are evenly arranged along the circumference at the lower end of the upper grooved wheel (91), and multiple second ramps (920) are evenly arranged along the circumference at the upper end of the lower grooved wheel (92). A low groove (921) and a high groove (922) are respectively arranged at both ends of the second ramp (920). The low groove (921) and the high groove (922) correspond to two adjacent first ramps (910).

2. The telescopic blade PDC drill bit according to claim 1, characterized in that, A sliding ring (2) is coaxially rotatably provided on the inner wall of the outer cylinder (20), and at least one of the sliding ring shafts (4) is provided on the inner wall of the sliding ring (2), with the central axis of the sliding ring shaft (4) coinciding with the diameter of the sliding ring (2).

3. The telescopic blade PDC drill bit according to claim 2, characterized in that, The slip ring shaft (4) is rotatably connected to the slip ring (2) via a bearing (3).

4. The telescopic blade PDC drill bit according to any one of claims 1 to 3, characterized in that, When the movable blade (11) is in working condition, the height difference between the working end faces of the movable blade (11) and the fixed blade (13) is zero. When the movable blade (11) is not in working condition, the height difference between the working end faces of the movable blade (11) and the fixed blade (13) is 0-5mm.

5. The telescopic blade PDC drill bit according to any one of claims 1 to 3, characterized in that, The movable blade (11) is fixedly connected to the core tube (14) by a pin (8). A pin hole (140) is provided radially on the outer wall of the core tube (14), and a through hole (111) is provided radially on the movable blade (11). The pin (8) is located in the pin hole (140) and the through hole (111).

6. The telescopic blade PDC drill bit according to any one of claims 1 to 3, characterized in that, The outer cylinder (20) includes: Outer shell (5); The upper connector (1) is provided at the upper end of the outer casing (5); And a lower connector (7) provided at the lower end of the outer casing (5); The elastic element (6) has its axial ends abutting the core tube (14) and the lower connector (7) respectively, and the slip ring shaft (4) is disposed between the upper connector (1) and the outer shell (5).

7. The telescopic blade PDC drill bit according to claim 6, characterized in that, A drill bit body (110) is fixedly provided at one end of the lower connector (7) away from the outer shell (5), the fixed blade (13) is fixedly provided on the drill bit body (110), and the movable blade (11) is axially sealed and slidably provided on the drill bit body (110).

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