PDC drill bit with impact function

Abstract

The PDC drill bit with the impact function comprises a drill bit body and an impact generating device, a flow passing channel is formed in the drill bit body, the impact generating device comprises a rotary driving part, a cylindrical cam, an impact hammer and a supporting assembly, a cam block is fixedly arranged on the impact hammer, a curve groove is formed in the cylindrical side wall of the cylindrical cam, and the cylindrical cam is fixedly connected with the supporting assembly. And the cam block can be inserted into the curve groove in a sliding manner and can form a cam pair with the cylindrical cam. The rotary driving part is connected with the cylindrical cam and can drive the cylindrical cam to rotate together when fluid flows through the flow passing channel so as to drive the punch hammer to move up and down in a reciprocating mode through the cam pair, and impact force generated by downward movement of the punch hammer can act on the drill bit body or act on a punch head which is installed in the drill bit body and can stretch out or retract back to the drill bit body. The PDC drill bit with the impact function is simple in structure, the rock breaking efficiency of the drill bit can be effectively improved, and the problem that the rock breaking efficiency of hard formations difficult to drill in a deep well is low is solved.

Description

Technical Field

[0001] The present invention relates to the fields of technical equipment for oil and gas drilling engineering, mining engineering, building foundation engineering construction, geological drilling, tunnel engineering, hydrology and trenchless drilling, and in particular to a PDC drill bit with impact function. Background Art

[0002] Polycrystalline diamond composite drill bits are referred to as PDC (polycrystalline diamond compact bit) drill bits. PDC drill bits rely on high-hardness, wear-resistant, self-sharpening polycrystalline diamond composite pieces (referred to as PDC teeth or cutting teeth) as cutting elements to shear and crush rocks. PDC drill bits have high mechanical penetration speed, long service life, and low drilling cost in soft to medium-hard formations, so they are widely used in drilling oil and gas wells.

[0003] Although PDC teeth have high hardness, their impact resistance and thermal wear resistance are limited. When PDC drill bits drill in hard formations, highly abrasive formations, and severely inhomogeneous formations (soft and hard interlayers, gravel-containing layers, etc.), it is easy to cause rapid wear and failure of the composite piece. One of the most typical forms of failure is the impact collapse of the diamond layer of the composite piece. The collapse of the composite piece greatly reduces the cutting efficiency and working life of the drill bit. The main reason for the collapse of the composite piece is the impact force from the bottom of the well. In addition to the impact caused by the inhomogeneity of the rock, in more cases, the impact force borne by the cutting teeth comes from the vibration of the drill bit, especially the lateral vibration. Usually, the most prone position of composite piece collapse on the drill bit is the crown of the drill bit with a relatively high cutting speed and the radial area outside the crown. Excessive wear of the cutting teeth in the local radial area of ​​the drill bit will produce annular grooves on the blade body. Once the annular groove appears, the cutting ability of the drill bit is basically lost. Summary of the invention

[0004] The purpose of the present invention is to provide a PDC drill bit with an impact function, which has a simple structure and can effectively improve the rock breaking efficiency of the drill bit, thereby solving the problem of low rock breaking efficiency in hard formations that are difficult to drill in deep wells.

[0005] The object of the present invention is achieved by providing a PDC drill bit with an impact function, comprising:

[0006] The drill bit body has an axially extending flow passage therein and a plurality of rock breaking blades at the lower end thereof, and a plurality of cutting teeth are arranged on the rock breaking blades;

[0007] An impact generating device is arranged in a flow passage, and comprises a rotating driving member, a cylindrical cam, a hammer and a supporting assembly; the cylindrical cam is axially positioned in the flow passage so as to be rotatable through the supporting assembly, and the hammer is inserted in the supporting assembly so as to be movable up and down; a cam block is fixedly arranged on the hammer, and a curved groove is provided on the cylindrical side wall of the cylindrical cam, the cam block can be slidably inserted in the curved groove and can form a cam pair with the cylindrical cam; the rotating driving member is connected to the cylindrical cam, and can drive the cylindrical cam to rotate together when the fluid flows through the flow passage, so as to drive the hammer to reciprocate up and down through the cam pair, and can apply the impact force generated by the downward movement of the hammer to the drill body or to the punch installed in the drill body and capable of extending or retracting into the drill body.

[0008] In a preferred embodiment of the present invention, an anvil is provided at the bottom of the flow channel and below the hammer, the bottom surface of the anvil can be against the drill body, and the lower end of the hammer can exert an impact force on the anvil when the hammer moves downward to transfer the impact force to the drill body.

[0009] In a preferred embodiment of the present invention, a connecting piece is connected to the lower end of the hammer, and at least one mounting cavity is provided in the drill bit body, the upper end of the mounting cavity is connected to the flow channel, and the lower end thereof is connected to the rock breaking end of the corresponding rock breaking blade; a punch capable of axial movement is provided in each mounting cavity, and the upper end of each punch is connected to the connecting piece. The hammer can drive each punch to move axially through the connecting piece during the up and down movement, so that the lower end of the punch extends out of or retracts into the mounting cavity.

[0010] In a preferred embodiment of the present invention, the axis of the punch is parallel to the axis of the hammer; the connecting member includes at least one transverse connecting rod, the axis of the transverse connecting rod is perpendicular to the axis of the hammer, the first end of the transverse connecting rod is connected to the lower end of the hammer, and the second end of the transverse connecting rod is fixedly connected to the upper end of the corresponding punch.

[0011] In a preferred embodiment of the present invention, the distance between the axis of the punch and the axis of the drill body satisfies 0≤S≤2 / 3R; wherein S is the distance between the axis of the punch and the axis of the drill body, and R is the radius of the drill body.

[0012] In a preferred embodiment of the present invention, an angle is provided between the axis of the punch and the axis of the hammer, and the axis of the punch is arranged obliquely outward and downward from the center of the drill body; the connecting piece includes an adapter and at least one oblique connecting rod, the lower end of the hammer is connected to the first end of each oblique connecting rod through the connecting piece, and the second end of the oblique connecting rod is fixedly connected to the upper end of the corresponding punch, and the hammer can drive the punch to move back and forth along its axial direction through the adapter and the oblique connecting rod.

[0013] In a preferred embodiment of the present invention, an impact tooth is installed at the lower end of the punch.

[0014] In a preferred embodiment of the present invention, the impact teeth are conical teeth, wedge-shaped teeth or spherical teeth.

[0015] In a preferred embodiment of the present invention, the rotary drive member includes a connecting shaft and an impeller, the impeller and the cylindrical cam are both sleeved and fixed on the connecting shaft, and the cylindrical cam is arranged close to the lower end of the drill body, and the impeller has a plurality of blades arranged circumferentially at intervals, and the plurality of blades can drive the impeller to rotate under the action of the fluid.

[0016] In a preferred embodiment of the present invention, the support assembly includes two support plates arranged in parallel and spaced apart from each other, the two support plates are fixedly connected to the drill body, the connecting shaft and the hammer are located between the two support plates, the two ends of the connecting shaft are rotatably connected to the two support plates, and the two ends of the hammer pass through corresponding through holes opened on the two support plates.

[0017] As described above, the PDC drill bit in the present invention can convert the energy of the fluid flowing through the flow channel into the impact force of the hammer by setting an impact generating device in the drill bit body, and realize the up and down reciprocating motion of the hammer by using the cylindrical cam and the cam block on the hammer. Since the cylindrical cam is a spatial cam, the cam block is always in sliding contact with the cylindrical cam and moves up and down with the rotation of the cylindrical cam, thereby driving the hammer to move up and down. The entire movement process of the hammer is a continuous movement process, and the impact force generated is a flexible impact rather than a hard impact. The impact is relatively mild, which is more conducive to improving the service life of the drill bit. The reset of the hammer does not require other auxiliary components such as springs, and can be achieved by relying solely on the rotation of the cylindrical cam. The structure is simpler and more reliable. The entire impact generating device is a purely mechanical structure with high energy transfer efficiency, no need for pressure holding, can reduce damage to the upper drill string and drill bit, and is more conducive to extending the service life of the drill bit. At the same time, by applying the impact to the drill bit body or the punch inside the drill bit body, and using a combination of dynamic and static methods or impact-scraping and cutting methods to break the rock, the rock breaking efficiency of the drill bit can be effectively improved, solving the problem of low rock breaking efficiency in hard formations that are difficult to drill in deep wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0019] in:

[0020] Figure 1 : A schematic structural diagram of a PDC drill bit with impact function provided by the present invention.

[0021] Figure 2 : Another structural schematic diagram of the PDC drill bit with impact function provided by the present invention.

[0022] Figure 3: Another structural schematic diagram of the PDC drill bit with impact function provided by the present invention.

[0023] Figure 4 :for Figure 3 A simplified structural diagram showing the position relationship between the punch and cutting teeth.

[0024] Figure 5 : A schematic diagram of the structure of the punch provided by the present invention when it is arranged obliquely.

[0025] Figure 6 : A schematic structural diagram of the impact generating device provided by the present invention.

[0026] Description of Figure Numbers:

[0027] 1. Drill bit body; 11. Flow passage; 12. Rock breaking blade; 121. Cutting teeth; 13. Joint; 14. End head; 15. Spray hole; 16. Mounting cavity;

[0028] 2. Rotating driving member; 21. Connecting shaft; 211. Impeller shaft; 212. Cylindrical cam shaft; 22. Impeller;

[0029] 3. Cylindrical cam; 31. Curved groove;

[0030] 4. hammer; 41. cam block; 42. transverse connecting rod;

[0031] 5. Support plate;

[0032] 6. Chopping board;

[0033] 7. Punch; 71. Impact tooth; 72. Protrusion. DETAILED DESCRIPTION

[0034] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0035] like Figures 1 to 6 As shown, this embodiment provides a PDC drill bit with impact function, including:

[0036] The drill bit body 1 has an axially extending flow passage 11 therein, and a plurality of rock breaking blades 12 are provided at the lower end thereof, and a plurality of cutting teeth 121 are provided on the rock breaking blades 12;

[0037] An impact generating device is arranged in a flow passage 11, and comprises a rotary drive member 2, a cylindrical cam 3, a hammer 4 and a support assembly; the cylindrical cam 3 is rotatably positioned axially in the flow passage 11 through the support assembly, and the hammer 4 is arranged in the support assembly so as to be movable up and down; a cam block 41 is fixedly provided on the hammer 4, and a curved groove 31 is provided on the cylindrical side wall of the cylindrical cam 3, the cam block 41 can be slidably inserted in the curved groove 31 and can form a cam pair with the cylindrical cam 3; the rotary drive member 2 is connected to the cylindrical cam 3, and can drive the cylindrical cam 3 to rotate together when the fluid flows through the flow passage 11, so as to drive the hammer 4 to reciprocate up and down through the cam pair, and can make the impact force generated by the downward movement of the hammer 4 act on the drill body 1 or on the punch 7 installed in the drill body 1 and capable of extending or retracting the drill body 1.

[0038] Among them, the upper and lower directions mentioned in the text only refer to Figures 1 to 3 The upper and lower positions are shown in the figure for easy understanding. When in use, the upper end of the drill bit body 1 is connected to the drill rod so that the entire drill bit is lowered into the oil well together with the drill rod. The fluid (such as drilling fluid) flows through the flow channel 11, and the cylindrical cam 3 rotates, thereby driving the hammer 4 to reciprocate up and down to generate an impact force. When the impact force on the hammer 4 directly impacts the entire drill bit body 1, the drill bit can break the bottom of the well by combining dynamic and static (i.e., combining impact vibration with drilling pressure) to improve the energy utilization of the drill bit, and the impact force acts on the entire drill bit. When breaking the rock, the force dispersed on each cutting tooth 121 is relatively small, which can be more conducive to protecting the entire drill bit and increasing the service life of the cutting tooth 121. When the impact force on the hammer 4 acts on the punch 7, the drill bit can break the bottom of the well through a mixed method of impact-scraping (i.e., using the impact of the punch 7 and the scraping of the cutting teeth 121) to improve the drilling efficiency of the drill bit, and the cutting teeth 121 are no longer subjected to impact loads, thereby reducing the probability of impact failure of the cutting teeth 121, which is beneficial to extending the service life of the drill bit.

[0039] Therefore, the PDC drill bit in the present application can convert the energy of the fluid (such as drilling fluid) flowing through the flow channel 11 into the impact force of the hammer 4 by setting an impact generating device in the drill bit body 1, and realize the up and down reciprocating motion of the hammer 4 by using the cylindrical cam 3 and the cam block 41 on the hammer 4. Since the cylindrical cam 3 is a spatial cam, the cam block 41 is always in sliding contact with the cylindrical cam 3 and moves up and down with the rotation of the cylindrical cam 3, thereby driving the hammer 4 to move up and down. The entire movement process of the hammer 4 is a continuous movement process, and the impact force generated is a flexible impact rather than a hard impact. The impact is relatively mild, which is more conducive to improving the service life of the drill bit. The reset of the hammer 4 does not require other auxiliary components such as springs, and can be achieved by only relying on the rotation of the cylindrical cam 3. The structure is simpler and more reliable. The entire impact generating device is a purely mechanical structure with high energy transmission efficiency, no pressure holding, can reduce damage to the upper drill string and drill bit, and is more conducive to extending the service life of the drill bit. At the same time, the impact is applied to the drill body 1 or the punch 7 inside the drill body 1, and rock breaking is carried out by combining dynamic and static methods or impact-scraping methods, which can effectively improve the rock breaking efficiency of the drill bit and solve the problem of low rock breaking efficiency in hard formations that are difficult to drill in deep wells.

[0040] Specifically, the drill bit body 1 generally includes a joint 13 and an end portion 14 connected in an upper and lower manner. The joint 13 is a tubular structure and is used to connect to the drill rod. A plurality of rock-breaking blades 12 are evenly spaced along the circumference of the end portion 14, and a chip groove is formed in the area between two adjacent rock-breaking blades 12. A plurality of cutting teeth 121 are evenly arranged on each blade, and the rock-breaking blades 12 drive the cutting teeth 121 to rotate to achieve rock breaking. It can be understood that a plurality of spray holes 15 are opened in the lower end of the drill bit body 1, and the upper end of each spray hole 15 is connected to the lower end of the flow channel 11, and the lower end of each spray hole 15 passes through the drill bit body 1 downward, that is, passes through the end portion 14 downward, and generally each spray hole 15 is connected to the corresponding chip groove.

[0041] For the embodiment in which the impact force of the hammer 4 acts directly on the drill body 1, refer to Figure 1 An anvil 6 is provided at the bottom of the flow channel 11 and below the hammer 4. The bottom surface of the anvil 6 can be against the drill body 1. The lower end of the hammer 4 can exert an impact force on the anvil 6 when the hammer 4 moves downward, so as to transmit the impact force to the drill body 1.

[0042] During installation, the anvil 6 can be directly placed at the bottom of the flow channel 11 to abut against the drill body 1. The area of ​​the anvil 6 is relatively small, which is smaller than the flow area of ​​the flow channel 11 and will not affect the flow of the drilling fluid. The hammer 4 directly acts on the anvil 6 during impact, which can protect the drill body 1 to a certain extent.

[0043] In this way, when working, the impact generating device directly impacts the drill bit body 1, relying on the high-pressure energy of the drilling fluid to break the rock and improve the energy utilization rate of the drill bit; the drill bit uses the impact method to obtain large-sized rock cuttings, and relies on large rock cuttings to determine the geological stratum; when the drill bit is directional drilling, due to the bending of the wellbore trajectory and the irregularity of the well wall, the friction resistance between the drill string and the drill bit and the wellbore increases, especially in horizontal wells, some rock cuttings near the drill bit cannot be removed in time, forming sand at the bottom of the well, which hinders the drill bit from drilling forward, and there is a certain frequency of impact vibration in the drill bit body 1, which reduces the friction resistance between the drill bit and the wellbore, reduces the wrapping force of the sand at the bottom of the well on the drill bit, and thus reduces the occurrence of decompression of the drill bit.

[0044] For the embodiment in which the impact force of the hammer 4 acts on the punch 7 in the drill body 1, refer to Figure 2 and Figure 3 A connecting piece is connected to the lower end of the hammer 4, and at least one mounting cavity 16 is provided in the drill bit body 1. The upper end of the mounting cavity 16 is communicated with the flow channel 11, and the lower end thereof is communicated with the rock breaking end of the corresponding rock breaking blade 12; a punch 7 capable of axial movement is provided in each mounting cavity 16, and the upper end of each punch 7 is connected to the connecting piece. The hammer 4 can drive each punch 7 to move axially through the connecting piece during the up and down movement, so that the lower end of the punch 7 extends out of or retracts into the mounting cavity 16.

[0045] In this way, the impact generated by the impact generating device directly acts on the rock breaking punch 7 during operation, and the cutting teeth 121 are no longer subjected to impact loads, which can reduce the probability of impact failure of the cutting teeth 121 and is beneficial to extending the service life of the drill bit.

[0046] The punch 7 can be, for example, a columnar structure, whose shape matches the shape of the mounting cavity 16, and specifically moves along the axial direction of the mounting cavity 16. The number of mounting cavities 16 is the same as the number of punches 7; when there are multiple mounting cavities 16, the number of mounting cavities 16 corresponding to each rock breaking blade 12 can be the same or different, depending on the needs.

[0047] In specific arrangement, the axis of the punch 7 may be parallel to the axis of the hammer 4, or there may be an angle between them.

[0048] When the axis of the punch 7 is parallel to the axis of the hammer 4, the structure of the connecting piece can be realized as follows: Figure 2 and Figure 3 The connecting member includes at least one transverse connecting rod 42, the axis of the transverse connecting rod 42 is perpendicular to the axis of the hammer 4, the first end of the transverse connecting rod 42 is connected to the lower end of the hammer 4, and the second end of the transverse connecting rod 42 is fixedly connected to the upper end of the corresponding punch 7.

[0049] The number of transverse connecting rods 42 is the same as the number of punches 7. Multiple transverse connecting rods 42 can be integrally formed and then connected to the hammer 4, or multiple transverse connecting rods 42 can be independent components; the second end of each transverse connecting rod 42 extends into the corresponding mounting cavity 16 and is fixedly connected to the upper end of the corresponding punch 7. Generally, when the hammer 4 moves upward to the highest point, the lower end of the punch 7 is completely retracted into the mounting cavity 16 to ensure that the punch 7 can generate a sufficient impact distance; when the hammer 4 moves downward to the lowest point, the position where the lower end of the punch 7 extends out of the mounting cavity 16 should extend the corresponding cutting teeth 121 to ensure that the punch 7 bears the impact load.

[0050] Reference Figure 2 and Figure 3 , the distance R between the axis of the punch 7 and the axis of the drill body 1 satisfies 0≤S≤2 / 3R, where R is the radius of the drill body 1. Each punch 7 can be located at a different radial position of the drill body 1, which can improve the rock breaking efficiency of different areas of the drill bit. Specifically, it can be personalized according to the specific drilling process and conditions to expand the application range of the drill bit.

[0051] When an angle is provided between the axis of the punch 7 and the axis of the hammer 4, the axis of the punch 7 is arranged to be inclined outward and downward from the center of the drill body 1; the structure of the connecting piece can be realized as follows: the connecting piece includes an adapter and at least one oblique connecting rod, the lower end of the hammer 4 is connected to the first end of each oblique connecting rod through the connecting piece, the second end of the oblique connecting rod is fixedly connected to the upper end of the corresponding punch 7, and the hammer 4 can drive the punch 7 to move back and forth along its axial direction through the adapter and the oblique connecting rod.

[0052] Reference Figure 5 The angle a between the axis of the punch 7 and the axis of the hammer 4 satisfies 0°≤a≤45°, and the angle a is controlled within a certain range, so that the punch 7 can impact and crush the rock in each area of ​​the drill bit, improve the diversity of the drill bit design, and broaden the use range of the drill bit. The structure of the specific adapter can adopt any existing form that can realize this function, as long as the adapter and the oblique connecting rod can drive the punch 7 to move along the axial direction of the punch 7 when the hammer 4 moves up and down, and this application does not limit this.

[0053] Further preferably, refer to Figure 3 An impact tooth 71 is installed at the lower end of the punch 7. The impact tooth 71 can be a conical tooth, a wedge-shaped tooth or a spherical tooth. Different types of impact teeth 71 are arranged on the punch 7, which can be applied to formations of different hardness, providing an optional solution for the selection of the drill bit.

[0054] Similarly, generally when the impact ram 4 moves upward to the highest point, the impact teeth 71 are completely retracted into the installation cavity 16 to ensure that the impact teeth 71 can generate sufficient impact distance; when the impact ram 4 moves downward to the lowest point, the position where the impact teeth 71 extend out of the installation cavity 16 should extend beyond the corresponding cutting teeth 121 to ensure that the impact teeth 71 bear the impact load.

[0055] Generally, the value range of the relative height M between the position where the impact teeth 71 extend out of the installation cavity 16 and the cutting teeth 121 is: 0 < M ≤ 5 mm. The position of the impact teeth 71 after the impact should be lower than the corresponding cutting teeth 121. In this way, the impact teeth 71 impact and break the rock, and the cutting teeth 121 scrape and break the rock. When designing the drill bit, the relative positions of the impact teeth 71 and the cutting teeth 121 are adjusted according to different lithologies and drilling methods, so as to improve the adaptability of the drill bit to the formation and the rock-breaking efficiency of the drill bit.

[0056] Generally, for the solution where the lower end of the punch 7 is not provided with impact teeth 71, refer to Figure 2 , the lower end of the punch 7 preferably has a downward protruding protrusion 72 to facilitate impact rock breaking.

[0057] Furthermore, in order to facilitate the rotary driving member 2 to drive the cylindrical cam 3 to rotate under the action of the fluid, refer to Figure 6 , the rotary driving member 2 includes a connecting shaft 21 and an impeller 22. Both the impeller 22 and the cylindrical cam 3 are sleeved and fixed on the connecting shaft 21, and the cylindrical cam 3 is arranged near the lower end of the drill bit body 1. The impeller 22 has a plurality of blades arranged at circumferential intervals, and the plurality of blades can push the impeller 22 to rotate under the action of the fluid.

[0058] In order to facilitate the axial positioning of the cylindrical cam 3 by the support assembly and the guiding of the impact ram 4, the support assembly includes two support plates 5 arranged in parallel at an interval up and down. Both support plates 5 are fixedly connected to the drill bit body 1. The connecting shaft 21 and the impact ram 4 are both located between the two support plates 5. The two ends of the connecting shaft 21 are respectively rotatably connected to the two support plates 5, and the two ends of the impact ram 4 respectively pass through the corresponding through holes opened on the two support plates 5.

[0059] Among them, the axes of the connecting shaft 21 and the hammer 4 are parallel to the axis of the flow channel 11 (that is, parallel to the axis of the drill body 1). Generally, in order to facilitate processing and installation, the connecting shaft 21 includes an impeller shaft 211 and a cylindrical cam shaft 212 that are coaxially fixed to each other. The impeller 22 is sleeved and fixed on the impeller shaft 211, and the cylindrical cam 3 is sleeved and fixed on the cylindrical cam shaft 212. The connecting shaft 21 and the hammer 4 are arranged side by side between two support plates 5, and one side of the support plate 5 is fixed to the wall surface of the flow channel 11. The blades on the impeller 22 can be spiral blades, for example, to achieve rotation under the action of the fluid without the need for other power devices. The curved groove 31 on the cylindrical cam 3 extends from the higher point on the cylindrical surface of the cylindrical cam 3 along the circumferential direction to the lower point of the cylindrical surface and then extends along the circumferential direction back to the higher point, forming a closed curve to ensure that the hammer 4 can be reciprocated up and down through the cam block 41 under the continuous rotation of the cylindrical cam 3. During operation, the drilling fluid drives the impeller 22 to rotate when passing through the flow channel 11 in the drill bit. The impeller 22 drives the cylindrical cam 3 to rotate through the impeller shaft 211. With the cooperation of the cam block 41 and the cylindrical cam 3, the cam block 41 drives the hammer 4 to move, thereby converting the rotational motion of the impeller 22 into the impact motion of the hammer 4.

[0060] In summary, the PDC drill bit in this embodiment has the following advantages:

[0061] (1) The drill bit relies on an impact generating device to form an impact of a certain frequency inside the drill bit body. The impact generating device is a purely mechanical transmission structure with high energy transfer efficiency. It does not require pressure holding, reduces damage to the drill string and the drill bit, and is beneficial to extending the service life of the drill bit.

[0062] (2) The energy of the drilling fluid is used to break the rock, thereby improving the utilization rate of the drilling fluid energy of the drill bit. The drill bit breaks the bottom of the well through a combination of dynamic and static methods or a mixed impact-scraping method, thereby improving the drilling efficiency of the drill bit.

[0063] (3) The amplitude and frequency of the impact vibration generated by the impact generating device are appropriate, which can not only effectively break the rock, but also avoid the impact failure of the PDC teeth, thereby increasing the service life of the drill bit.

[0064] (4) Vibration of a certain frequency is generated in the drill bit body, which reduces the contact pressure between the drill bit and the wellbore, reduces the contact area between the wellbore and the well wall, and thus reduces the friction resistance between the wellbore and the well wall, thereby reducing the occurrence of decompression of the drill bit.

[0065] The above are only exemplary embodiments of the present invention and are not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A PDC drill bit with impact function, It is characterized in that include: A drill bit body, which has an axially extending flow passage therein and a plurality of rock breaking blades at its lower end, wherein the rock breaking blades are provided with a plurality of cutting teeth; An impact generating device is arranged in the flow channel, and comprises a rotary drive member, a cylindrical cam, a hammer and a support assembly; the cylindrical cam is rotatably positioned axially in the flow channel through the support assembly, and the hammer is arranged in the support assembly so as to be movable up and down; a cam block is fixedly arranged on the hammer, and a curved groove is opened on the cylindrical side wall of the cylindrical cam, the cam block can be slidably inserted in the curved groove and can form a cam pair with the cylindrical cam; the rotary drive member is connected to the cylindrical cam, and can drive the cylindrical cam to rotate together when the fluid flows through the flow channel, so as to drive the hammer to reciprocate up and down through the cam pair, and can apply the impact force generated by the downward movement of the hammer to the drill body or to the punch installed in the drill body and capable of extending or retracting into the drill body.

2. The PDC drill bit with impact function as claimed in claim 1, It is characterized in that An anvil is provided at the bottom of the flow channel and below the hammer, the bottom surface of the anvil can be against the drill body, and the lower end of the hammer can exert an impact force on the anvil when the hammer moves downward, so as to transfer the impact force to the drill body.

3. The PDC drill bit with impact function as claimed in claim 1, It is characterized in that A connecting piece is connected to the lower end of the hammer, and at least one installation cavity is provided in the drill bit body. The upper end of the installation cavity is communicated with the flow channel, and the lower end thereof is communicated with the rock breaking end of the corresponding rock breaking blade wing; a punch capable of axial movement is provided in each of the installation cavities, and the upper end of each of the punches is connected to the connecting piece. The hammer can drive each of the punches to axially move through the connecting piece during the up and down movement, so that the lower end of the punch extends out of or retracts into the installation cavity.

4. The PDC drill bit with impact function as claimed in claim 3, It is characterized in that The axis of the punch is parallel to the axis of the hammer; The connecting member includes at least one transverse connecting rod, the axis of which is perpendicular to the axis of the hammer, the first end of which is connected to the lower end of the hammer, and the second end of which is fixedly connected to the upper end of the corresponding punch.

5. The PDC drill bit with impact function as claimed in claim 4, Features The distance between the axis of the punch and the axis of the drill body satisfies 0≤S≤2 / 3R; Wherein, S is the distance between the axis of the punch and the axis of the drill body, and R is the radius of the drill body.

6. The PDC drill bit with impact function as claimed in claim 3, It is characterized in that An included angle is provided between the axis of the punch and the axis of the hammer, and the axis of the punch is arranged to be inclined outward and downward from the center of the drill body; The connecting member includes an adapter and at least one oblique connecting rod. The lower end of the hammer is connected to the first end of each oblique connecting rod through the connecting member, and the second end of the oblique connecting rod is fixedly connected to the upper end of the corresponding punch. The hammer can drive the punch to move back and forth along its axial direction through the adapter and the oblique connecting rod.

7. The PDC drill bit with impact function as claimed in claim 3, It is characterized in that An impact tooth is installed at the lower end of the punch.

8. The PDC drill bit with impact function as claimed in claim 7, It is characterized in that The impact teeth are conical teeth, wedge-shaped teeth or spherical teeth.

9. The PDC drill bit with impact function as claimed in claim 1, It is characterized in that The rotary drive member includes a connecting shaft and an impeller. The impeller and the cylindrical cam are both sleeved and fixed on the connecting shaft, and the cylindrical cam is arranged close to the lower end of the drill body. The impeller has a plurality of blades arranged circumferentially at intervals, and the plurality of blades can drive the impeller to rotate under the action of fluid.

10. The PDC drill bit with impact function according to claim 9, It is characterized in that The support assembly includes two support plates arranged in parallel and spaced apart from each other, the two support plates are fixedly connected to the drill body, the connecting shaft and the hammer are located between the two support plates, the two ends of the connecting shaft are rotatably connected to the two support plates, and the two ends of the hammer pass through corresponding through holes opened on the two support plates.

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