Combined special-shaped roller bit

Abstract

The present application belongs to the technical field of drill bits for oil and gas drilling and rock drilling in geological exploration, and provides a combined special-shaped roller bit. The present application comprises a roller body and cutting teeth arranged thereon, the cutting teeth comprising extrusion teeth and chisel teeth working in time sequence: along the rotation direction of the roller body, at least one group of paired units composed of extrusion teeth and chisel teeth are arranged in time sequence, the extrusion teeth contacting the bottom rock before the chisel teeth; the impact side of the extrusion teeth is provided with a jointing slope surface for manufacturing cracks in rock in advance; the cutting edge of the chisel tooth is aligned with the root area of the crack manufactured by the extrusion tooth in time sequence and space to wedge into the rock along the crack to perform a chisel action; the chisel tooth is further provided with a hydraulic buffer structure at the root position and connected with the roller body; wherein the hydraulic buffer structure is configured to allow the chisel tooth to produce a retraction displacement to absorb impact energy when the chisel tooth bears a load exceeding a preset threshold.

Description

Technical Field

[0001] This invention relates to the field of drill bit technology for drilling in mining, oil and gas wells and geological exploration, specifically to a combined special-shaped roller cone drill bit. Background Technology

[0002] In oil and gas drilling and mining rock drilling operations, roller cone bits are the main tools for breaking rocks. The bit body is equipped with several roller cones, each with multiple rings of cutting teeth. During drilling, the roller cones rotate on their own axis and revolve around the bottom of the well under the action of drilling pressure and rotation, while the cutting teeth periodically impact, squeeze, and scrape the rock at the bottom of the well.

[0003] In traditional roller cone designs, the cutting teeth on the same gear ring are of the same type, such as wedge-shaped or conical teeth, evenly spaced circumferentially. Each cutting tooth impacts and compresses the rock independently, contacting a completely untreated rock surface without prior tooth treatment. There is no division of labor or coordination among the teeth for rock breaking. All cutting teeth are rigidly fixed to the roller cone housing using interference fit or welding, with no buffering mechanism between the teeth and the housing. This design easily leads to low rock-breaking energy utilization and limited mechanical drilling speed. Independent operation results in localized fracture pits and irregular crack propagation, a low proportion of large-volume rock cuttings being removed, and significant energy being consumed in repeated rock cutting grinding. Furthermore, it has poor resistance to abnormal impacts and is prone to chain-reaction tooth breakage. Rigid fixing allows the peak impact force to be directly transmitted to the tooth body and roller cone body; when this force exceeds the bending strength of the cemented carbide, tooth breakage occurs, and the failure of one tooth can trigger a chain reaction of damage to adjacent teeth. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a combined non-standard roller cone drill bit that can solve the problems of low rock-breaking efficiency and easy tooth breakage due to rigid connection of traditional cutting teeth.

[0005] This invention provides a combined special-shaped roller cone drill bit, comprising a roller cone body and cutting teeth arranged thereon. The cutting teeth include pressing teeth and shovel teeth that work in sequence: along the rotation direction of the roller cone body, at least one pair of paired units consisting of pressing teeth and shovel teeth are arranged sequentially, with the pressing teeth contacting the rock at the bottom of the well before the shovel teeth; the impact-facing side of the pressing teeth has a fracture-creating slope for creating a fracture in the rock first; the cutting edge of the shovel teeth is aligned temporally and spatially with the root region of the fracture created by the pressing teeth to wedge into the rock along the fracture and perform a shoveling action; the shovel teeth are also provided with a hydraulic buffer structure located at their root position and connected to the roller cone body; wherein the hydraulic buffer structure is configured to allow the shovel teeth to retract and absorb impact energy when the shovel teeth are subjected to a load exceeding a preset threshold.

[0006] Furthermore, the groove-creating slope of the extrusion tooth is composed of an upper slope and a lower slope. The upper slope is used to create radial cracks, and the lower slope is thickened to form a reinforcing rib. The back side of the extrusion tooth is set as a steep slope to provide operating space for the rear shovel tooth.

[0007] Furthermore, the shovel tooth has a forward tilt angle, its cutting surface is composed of an upper cutting slope and a lower thickened slope, and its back is provided with a single inclined surface for chip removal.

[0008] Furthermore, the squeezing teeth are primarily arranged in the inner region of the roller cone body, while the shovel teeth are primarily arranged in the outer region of the roller cone body, forming a zoned collaborative operation of inner squeezing and outer shoveling. In practical applications, the squeezing and shovel teeth, working in sequence, break the traditional mode of independent operation of existing roller cone cutting teeth. They are arranged sequentially along the rotation direction of the roller cone, with different functions, complementary shapes, and sequential relationships, forming a complete collaborative rock-breaking process of "first squeezing to crack, then shoveling and peeling." When the squeezing tooth impacts the rock at the bottom of the well, its sharp upper slope can efficiently create initial, directional radial cracks on the rock surface. The lower slope angle is increased, forming a thickened and reinforced rib structure to ensure the bending strength of the tooth and prevent fracture. The back side of the squeezing tooth is designed as a steep slope. Besides discharging rock cuttings, the more important function of this steep slope is that its inward-curving geometry provides a spacious, interference-free cutting space for the shovel teeth that follow. The forward tilt angle ensures that the cutting edge of the shovel tooth, in its timing and spatial position as it reaches the bottom of the well with the rotation of the tooth wheel, is precisely aligned with the root or extension area of ​​the crack created on the slope by the preceding extrusion tooth. This allows for precise wedging into the rock along the crack during further loading, performing shoveling and stripping, rather than blindly impacting or chiseling like traditional teeth. The cutting surface of the shovel tooth consists of an upper slope and a lower thickened slope. The lower thickened slope is used to strengthen the tooth tip and resist lateral wear and bending stress. The back of the shovel tooth has a single inclined surface for chip removal. This single inclined surface is specifically designed to smoothly guide and discharge large pieces of rock chips, preventing them from clogging between the teeth.

[0009] In terms of the macroscopic layout of the roller cone bit, this invention adopts functional zoning. The extrusion teeth are mainly arranged in the inner region of the roller cone body, that is, the region near the center line of the bit, and undertake the main impact pre-fracking function; the shovel teeth are mainly arranged in the outer ring region of the roller cone body, that is, the gauge-maintaining region near the well wall, and undertake the main functions of cuttings removal and well wall dressing and gauge maintenance. This forms a zoned and coordinated pattern of inner extrusion and outer shovel, allowing different types of teeth to exert maximum efficiency in their most advantageous radial positions.

[0010] Furthermore, the hydraulic buffer structure includes: the shovel tooth has a crown section and a column section, which are integrally formed; a sleeve, which is fixed in the mounting hole of the roller cone body; the column section and the inner hole of the sleeve are in a sliding sealing fit; a closed hydraulic cavity defined by the bottom end face of the column section and the bottom face of the inner hole of the sleeve; the closed hydraulic cavity is filled with an incompressible fluid medium. In practical applications, the purpose of this design is to provide a non-rigid, self-adaptive mounting structure for the shovel tooth, creating a controllable hydraulic buffer layer between the roller cone housing and the shovel tooth body.

[0011] Furthermore, the blade of the shovel is internally equipped with a hydraulic vibration chamber, which extends from the crown section to the column section and is in fluid communication with the closed hydraulic chamber. The hydraulic vibration chamber and the closed hydraulic chamber together form a composite cavity, configured such that, during drilling, in response to the alternating load borne by the blade, the internal fluid medium flows back and forth between the hydraulic vibration chamber and the closed hydraulic chamber to excite the blade to generate high-frequency micro-amplitude vibrations. In practical applications, this integrated hydraulic vibration function, combined with the aforementioned hydraulic buffer structure, passively excites high-frequency micro-amplitude vibrations of the blade during drilling. This vibration, on the one hand, reduces the effective friction coefficient of the cutting interface, making cutting smoother; on the other hand, it effectively prevents rock cuttings from adhering and accumulating, significantly reducing the risk of mud packing.

[0012] Furthermore, the connecting channel between the hydraulic excitation chamber and the closed hydraulic chamber is provided with a cross-sectional abrupt change structure or a damping orifice structure to enhance pressure fluctuations during fluid reciprocating flow, thereby strengthening high-frequency micro-amplitude vibration. In practical applications, the purpose of this design is to enhance high-frequency micro-amplitude vibration; on the one hand, high-frequency micro-amplitude vibration generates a "vibration lubrication" effect at the cutting interface between the shovel teeth and the rock, effectively reducing the effective friction coefficient between the shovel teeth and the rock, making the cutting smoother and reducing drilling torque.

[0013] Furthermore, the incompressible fluid medium is filled into the hydraulic excitation chamber and the closed hydraulic chamber, and the incompressible fluid medium is a high-viscosity grease or silicone oil. The purpose of this design is to make the two chambers and their connecting channels form a complete fluid-filled oscillation system. The viscosity characteristics and bulk modulus of the high-viscosity grease or silicone oil used as the incompressible fluid medium together determine the natural frequency and damping characteristics of the oscillation system.

[0014] Furthermore, the hydraulic buffer structure is configured such that, under overload, the retraction displacement of the shovel teeth is 0.1mm to 0.5mm, and after the load is removed, it is automatically reset by the fluid medium. In practical applications, the peak vibration displacement is always less than one-fifth of the normal cutting depth of the shovel teeth; by configuring it to be much smaller than the average cutting depth of the shovel teeth under normal drilling conditions, it is possible to avoid disrupting the precise cutting of the shovel teeth into the crack.

[0015] As can be seen from the above technical solution, the beneficial effects of the combined non-circular roller cone drill bit provided by the present invention are as follows: (1) In practical application, this design has achieved a transformation in rock breaking and improved drilling efficiency. Through the time-coordinated tooth arrangement system, the traditional "independent impact of each tooth" has been transformed into an orderly division of labor of "front tooth creating a gap and rear tooth stripping". The weak surface of the structure is created first and then targeted stripping is carried out, which greatly improves the energy utilization rate and mechanical drilling speed. Compared with the traditional single tooth drilling, the core idea of ​​this application is to advance from front to back, break first and then expand, and use the point to drive the surface of rock breaking in the drilling process. (2) The most important thing is that, due to the design concept of each tooth pressure performing its own function, the life of the shovel teeth is doubled and abnormal tooth breakage is effectively eliminated; the adaptive hydraulic buffer structure transforms the instantaneous peak impact force into a smooth load, eradicates the main failure mode of rigid tooth breakage, and increases the working life of the drill bit in complex formations by several times. (3) It can also achieve active mud prevention and reduce friction; the composite cavity composed of the hydraulic excitation cavity and the closed hydraulic cavity passively excites the high-frequency micro-amplitude vibration of the shovel teeth, which reduces the friction coefficient of the cutting interface on the one hand, and prevents rock cuttings from adhering and accumulating on the other hand, significantly reducing the risk of mud packing. (4) In actual work, the micro-leakage and fluid flow of the hydraulic buffer structure can dynamically compensate for the progressive wear of the cutting teeth, so that the key collaborative parameters such as the height difference, inclination angle and timing interval between the squeezing teeth and the shovel teeth remain effective in the long drilling cycle. (5) In general, the present invention organically integrates pairing logic, geometry, tilt angle and spacing, partition layout, hydraulic buffer structure and hydraulic excitation cavity to form a powerful, mutually constrained and synergistic overall technical solution, achieving unexpected technical effects. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, the elements or parts are not necessarily drawn to scale.

[0017] Figure 1 A three-dimensional schematic diagram of a combined irregular-shaped roller cone drill bit provided in an embodiment of the present invention; Figure 2 This is a three-dimensional schematic diagram of the extrusion teeth in this invention; Figure 3 This is a three-dimensional schematic diagram of the shovel teeth in this invention; Figure 4 This is a front view schematic diagram of the shovel teeth in this invention; Figure 5 This is a rear view schematic diagram of the shovel teeth in this invention; Figure 6 This is a schematic diagram of the mounting structure of the shovel teeth on the roller body in this invention; Figure 7 for Figure 6 Enlarged structural diagram at point A in the middle; Figure 8 This is a schematic diagram of the center distance L between the extrusion teeth and the shovel teeth in this invention; Figure 9 This is a schematic diagram of the forward tilt angle α in the installation position of the shovel teeth in this invention.

[0018] Figure label: 1. Roller body; 2. Extrusion tooth; 3. Shovel tooth; 4. Sleeve; 5. Sealing ring; 6. Snap ring; 7. Enclosed hydraulic cavity; 8. Hydraulic excitation cavity; 9. Connecting channel; 21. Upper slope; 22. Lower slope; 23. Steep slope; 31. Upper cutting edge slope; 32. Lower thickened slope; 33. Back slope; 35. Tooth crown section; 36. Tooth column section; 41. Bottom surface of sleeve inner hole; 91. Abrupt cross-section structure; 361. Bottom end face of tooth column section. Detailed Implementation

[0019] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0020] The basic implementation examples are as follows: Figures 1 to 9 As shown: Example See Figures 1 to 3 This embodiment provides a combined non-circular roller cone drill bit. The drill bit includes a roller cone body 1, on which multiple annularly arranged toothed rings are machined. For ease of explanation, the inner toothed ring is used as an example. It should be understood that the arrangement of other toothed rings can be adjusted in the same way or adaptively with reference to the inner toothed ring, and all fall within the protection scope of this invention.

[0021] Along the circumference of the inner toothed ring, multiple sets of paired units are arranged sequentially and cyclically according to the normal working direction of the drill bit's rotation. Each paired unit consists of a squeezing tooth 2 and a shoveling tooth 3 immediately following it. This fixed sequence of "squeezing and shoveling, squeezing before shoveling" constitutes the most basic temporal coordination relationship. The squeezing tooth 2 contacts the rock at the bottom of the well before the shoveling tooth 3, forming a sequential operation in time and a one-to-one correspondence in space.

[0022] In this embodiment, the center-to-center distance L between the extrusion tooth 2 and the shovel tooth 3 is specifically defined as a preset size that matches the fracture width D that the extrusion tooth 2 can generate in the target formation. Specifically, the center-to-center distance L is 0.8 to 1.2 times the fracture width D. By matching this distance, it is ensured that, in terms of timing, when the shovel tooth 3 reaches the bottom of the well, the fracture created by the extrusion tooth 2 is still open and has not yet closed; in terms of space, the cutting edge of the shovel tooth 3 falls precisely within the effective range of the fracture, thereby achieving precise wedging rather than blind drilling.

[0023] See Figure 2 The extrusion tooth 2 is a one-piece cemented carbide tooth. Its face facing the direction of rotation is the impact surface, which consists of an upper slope 21 and a lower slope 22 at an angle to each other. The upper slope 21 has a small and sharp angle, its function being to efficiently create initial, directional radial cracks on the rock surface when the extrusion tooth 2 impacts the rock at the bottom of the well. The lower slope 22 has a significantly increased angle, smoothly transitioning with the tooth column to form a reinforcing rib structure, ensuring the bending strength of the tooth body and preventing breakage during impact. The face of the extrusion tooth 2 facing away from the direction of rotation is a steep slope 23, which is significantly inward-curving. Besides expelling some rock cuttings, the more important function of this steep slope 23 is that its inward-curving geometry provides a spacious, interference-free cutting space for the following shovel tooth 3, preventing structural collisions or chip blockages with the back of the extrusion tooth 2 during the shoveling action.

[0024] See Figure 3 - Figure 9 The shovel tooth 3 is installed with its entire body facing the direction of rotation, and its axis and the normal at the installation point form a forward tilt angle α. In this embodiment, the value of the forward tilt angle α is preferably 7° to 11°. More preferably, the value of the forward tilt angle α is 9°. By setting the above-mentioned forward tilt angle range, the cutting edge of the shovel tooth 3 can be precisely aligned with the root region of the crack created by the previous extrusion tooth 2 in terms of timing and spatial position when it reaches the bottom of the well as the tooth body 1 revolves. Thus, when further loading is applied, it can accurately wed into the rock along the crack and perform a shoveling and peeling action, rather than blindly impacting or chiseling the rock surface like traditional teeth.

[0025] The cutting edge of the shovel tooth 3 consists of two sections: an upper cutting slope 31 near the tooth tip and a lower thickened slope 32 for reinforcement. The lower thickened slope 32 strengthens the tooth tip, resists lateral wear and bending stress, and extends the service life of the shovel tooth 3. The back of the shovel tooth 3 is a straight backslope 33. This backslope 33 is specifically designed to smoothly guide and discharge large rock chips V cut off by the shovel, preventing rock chips from clogging between the teeth.

[0026] In terms of the macroscopic layout of the roller cone bit, this embodiment adopts functional zoning. In the inner region of the roller cone body 1, i.e., the region near the centerline of the bit, the squeezing teeth 2 are predominantly arranged to undertake the main impact pre-fracking function; in the outer region of the roller cone body 1, i.e., the gauge-maintaining region near the wellbore, the shoveling teeth 3 are predominantly arranged to undertake the main functions of cuttings removal and wellbore trimming and gauge maintenance. This forms a zoned collaborative pattern of inner squeezing and outer shoveling, allowing different types of teeth to exert maximum efficiency in their most advantageous radial positions. It should be noted that "predominant arrangement" means that within the corresponding area, the specified type of teeth constitutes the majority in number or undertakes the main rock-breaking task in that area, and does not exclude the inclusion of a small number of other types of teeth within the area to adapt to local formation variations.

[0027] See Figure 6 The innovation of this embodiment lies in the installation method and internal structure of the shovel tooth 3. The shovel tooth 3 is composed of an integrally formed crown section 35 and a column section 36. The crown section 35 is the bearing part exposed outside the gear body 1, and the column section 36 is the connecting part inserted into the gear body 1. Mounting holes are pre-machined on the gear body 1, and a steel sleeve 4 is fixed inside by interference fit or welding. The inner hole of the sleeve 4 and the column section 36 of the shovel tooth 3 form an axially sliding piston pair through a precision fit. A high-strength, high-temperature resistant sealing ring 5 is embedded near the opening of the inner hole of the sleeve 4 to form a liquid seal and prevent leakage of the internal fluid medium. A retaining ring 6 is inserted into the annular groove of the inner wall of the sleeve 4 and embedded in the limiting step on the column section 36 to limit the maximum outward extension position of the column section 36 and prevent the shovel tooth 3 from dislodging when not in operation.

[0028] Therefore, a closed hydraulic cavity 7 with constant space is formed between the bottom end face 361 of the toothed column section 36 and the bottom surface 41 of the inner hole of the sleeve 4. This closed hydraulic cavity 7 is filled with and permanently sealed with an incompressible fluid medium, preferably a high-viscosity grease or silicone oil, such as high-viscosity silicone oil. Through the above structure, a controllable hydraulic buffer layer is constructed between the toothed wheel housing 1 and the tooth 3, providing a non-rigid, self-adaptive mounting structure for the tooth 3.

[0029] More uniquely, the shovel tooth 3 also contains a hydraulic vibration chamber 8. This hydraulic vibration chamber 8 extends from the crown section 35 towards the column section 36, and its lower end is in fluid communication with the closed hydraulic chamber 7 through a connecting channel 9. The hydraulic vibration chamber 8 and the closed hydraulic chamber 7 together form a composite cavity. This composite cavity is configured such that, during drilling, in response to the alternating load borne by the shovel tooth 3, the internal fluid medium flows back and forth between the hydraulic vibration chamber 8 and the closed hydraulic chamber 7 to excite the shovel tooth 3 to generate high-frequency micro-amplitude vibrations.

[0030] In this embodiment, the connecting channel 9 is provided with a cross-sectional abrupt change structure 91 to enhance pressure fluctuations during fluid reciprocating flow, thereby strengthening high-frequency micro-amplitude vibrations. The cross-sectional abrupt change structure 91 can generate local pressure drops and velocity changes when fluid flows through it, exacerbating unstable fluid flow and thus generating more intense hydraulic oscillations. It is understood that the cross-sectional abrupt change structure 91 can be replaced with a damping orifice structure, or both can be provided simultaneously, to further enhance the vibration effect.

[0031] In practical work: During drilling, the drill bit body 1, bearing drill pressure, rotates in the direction of rotation. The extrusion tooth 2 takes the lead, impacting the rock with its upper slope 21, creating radial fractures. Immediately following, the paired shovel tooth 3 reaches the bottom of the well at a forward inclination angle α, for example, 9°, with its cutting edge facing the root region of the fracture. Under the combined action of drill pressure and torque, the shovel tooth 3 inserts into the fracture like a wedge, peeling off the large, fractured rock cuttings V from the parent rock at the bottom of the well. The peeled rock cuttings V are rapidly carried away from the bottom of the well by the drilling fluid flow along the open channel formed by the backslope 33 of the shovel tooth 3 and the steep slope 23 of the extrusion tooth 2, effectively preventing repeated breakage of the rock cuttings.

[0032] During normal drilling, the shovel tooth 3 is subjected to periodic alternating loads applied by the rock. During the load loading phase, the tooth column section 36 slightly retracts, squeezing some silicone oil from the closed hydraulic chamber 7 into the hydraulic vibration chamber 8 via the connecting channel 9. During the load unloading phase, the silicone oil flows back from the hydraulic vibration chamber 8 to the closed hydraulic chamber 7 via the connecting channel 9. Due to the presence of the abrupt cross-sectional structure 91 and the inertia and compressibility of the fluid itself, this reciprocating flow generates hydraulic oscillations within the composite cavity. These hydraulic oscillations further drive the shovel tooth 3 itself to generate high-frequency micro-amplitude vibrations. In this embodiment, the vibration amplitude during stable operation is controlled between 10 micrometers and 100 micrometers, and the peak vibration displacement is always less than one-fifth of the normal cutting depth of the shovel tooth 3. The high-frequency micro-amplitude vibration produces a "vibration lubrication" effect at the cutting interface between the shovel tooth 3 and the rock, effectively reducing the effective friction coefficient between the shovel tooth 3 and the rock, making the cutting smoother and reducing the drilling torque; at the same time, the vibration can also prevent rock cuttings from adhering and accumulating on the surface of the shovel tooth 3 and the cutting structure, significantly reducing the risk of mud packing on the shovel tooth, which is especially suitable for mud packing formations such as mudstone and shale.

[0033] When encountering a localized hard inclusion, if the squeezing tooth 2 fails to create a sufficient gap, the cutting tip of the shovel tooth 3 will directly impact the intact, hard rock. At this moment, the sudden increase in cutting reaction force overcomes the initial support force of the silicone oil within the closed hydraulic chamber 7. The silicone oil instantly undergoes elastic compression, causing the shovel tooth 3 to retract approximately 0.3 mm into the sleeve 4. This retraction process reduces the peak impact force and transforms it into a lower, slightly longer-lasting force. The energy is dissipated by the elastic compression and viscous flow of the silicone oil, effectively protecting the tooth tip. This retraction displacement is configured within the range of 0.1 mm to 0.5 mm, sufficient to absorb the vast majority of abnormal impact energy, fundamentally eliminating the risk of the tooth tip shattering due to overload.

[0034] When the drill bit passes the hard point, the abnormal reaction force disappears, and the compressed silicone oil expands immediately due to its own elastic restoring force, pushing the tooth column section 36 outward. The shovel tooth 3 precisely returns to its original working position, continuing the next cycle. The entire retraction and rebound process is completed in a very short time, much faster than the time it takes for the drill bit to rotate to the next tooth contacting the bottom of the well, and will not adversely affect the overall drilling efficiency. This cycle repeats continuously, achieving efficient, safe, and self-cleaning synergistic rock breaking.

[0035] In summary, this combined non-circular roller cone drill bit achieves high rock-breaking efficiency and extends the service life of the cutting teeth through the organic integration of cutting tooth pairing, geometry, zoned layout, hydraulic buffer structure, and hydraulic vibration chamber; therefore, this device is suitable for industry promotion.

[0036] Numerous specific details are set forth in this specification. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0037] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A combined irregular-shaped roller cone drill bit, comprising a roller cone body and cutting teeth arranged thereon, characterized in that, The cutting teeth include pressing teeth and scraping teeth that work in sequence: Along the rotation direction of the roller body, at least one set of paired units consisting of squeezing teeth and shovel teeth are arranged in sequence, with the squeezing teeth contacting the bottom rock of the well before the shovel teeth. The impact-facing side of the extrusion tooth has a crack-forming slope, which is used to create cracks in the rock in advance. The cutting edge of the shovel teeth is aligned with the root region of the crack created by the extrusion teeth in terms of timing and space, so as to wedge into the rock along the crack to perform a shoveling action. The shovel tooth is also provided with a hydraulic buffer structure located at its root and connected to the tooth body; wherein the hydraulic buffer structure is configured to allow the shovel tooth to generate a retraction displacement to absorb impact energy when the shovel tooth is subjected to a load exceeding a preset threshold.

2. The combined irregular-shaped roller cone drill bit according to claim 1, characterized in that, The groove-creating slope of the extrusion tooth consists of an upper slope and a lower slope. The upper slope is used to create radial cracks, and the lower slope is thickened to form a reinforcing rib. The back side of the extrusion tooth is set as a steep slope to provide operating space for the rear shovel tooth.

3. A combined irregular-shaped roller cone drill bit according to claim 1, characterized in that, The shovel teeth have a forward tilt angle, and their cutting surface is composed of an upper cutting slope and a lower thickened slope. Their back is provided with a single inclined surface for chip removal.

4. A combined irregular-shaped roller cone drill bit according to claim 1, characterized in that, The extrusion teeth are mainly arranged in the inner region of the roller body, and the shovel teeth are mainly arranged in the outer ring region of the roller body, forming a zoned cooperation of inner extrusion and outer shovel.

5. A combined irregular-shaped roller cone drill bit according to claim 1, characterized in that, The hydraulic buffer structure includes: The shovel tooth has a crown section and a column section, and is integrally formed; A sleeve is fixed inside the mounting hole of the toothed wheel body; the toothed section slides and seals with the inner hole of the sleeve. A closed hydraulic cavity is defined by the bottom end face of the toothed column section and the bottom surface of the inner hole of the sleeve; the closed hydraulic cavity is filled with an incompressible fluid medium.

6. A combined irregular-shaped roller cone drill bit according to claim 5, characterized in that, The inside of the shovel tooth is also provided with a hydraulic excitation chamber, which extends from the tooth crown section to the tooth column section and is in fluid communication with the closed hydraulic chamber; The hydraulic excitation chamber and the closed hydraulic chamber together form a composite cavity. This composite cavity is configured such that, during drilling, in response to the alternating load borne by the shovel teeth, the internal fluid medium flows back and forth between the hydraulic excitation chamber and the closed hydraulic chamber to excite the shovel teeth to generate high-frequency micro-amplitude vibrations.

7. A combined irregular-shaped roller cone drill bit according to claim 6, characterized in that, The communication channel between the hydraulic excitation chamber and the closed hydraulic chamber is provided with a cross-sectional abrupt change structure or a damping hole structure to enhance the pressure fluctuation during fluid reciprocating flow, thereby strengthening high-frequency micro-amplitude vibration.

8. A combined irregular-shaped roller cone drill bit according to claim 6, characterized in that, The incompressible fluid medium is filled into the hydraulic excitation chamber and the closed hydraulic chamber, and the incompressible fluid medium is a high-viscosity lubricating grease or silicone oil.

9. A combined irregular-shaped roller cone drill bit according to claim 5, characterized in that, The hydraulic buffer structure is configured such that, in the event of overload, the retraction displacement of the shovel teeth is 0.1 mm to 0.5 mm, and after the load is removed, it is automatically reset by the fluid medium.

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