CN112483005B

CN112483005B - Rock breaking drill bit for underground drilling tool

Info

Publication number: CN112483005B
Application number: CN201910864077.6A
Authority: CN
Inventors: 玄令超; 孙明光; 刘晓丹; 张海平; 臧艳彬; 王甲昌; 张仁龙
Original assignee: China Petroleum and Chemical Corp; Sinopec Research Institute of Petroleum Engineering
Current assignee: China Petroleum and Chemical Corp; Sinopec Research Institute of Petroleum Engineering
Priority date: 2019-09-12
Filing date: 2019-09-12
Publication date: 2023-01-20
Anticipated expiration: 2039-09-12
Also published as: CN112483005A

Abstract

The invention provides a rock breaking drill bit for a downhole drilling tool, comprising: the drill bit comprises a drill bit base body, wherein a first cavity and a second cavity are arranged in the drill bit base body; the power mechanism is arranged in the first cavity and comprises an impeller capable of rotating under the action of the drilling fluid; the impact generating mechanism is connected to the lower end of the power mechanism and can generate periodic water hammer pulse pressure under the rotation action of the impeller; the impact mechanism is arranged in the second cavity and is connected with the impact generation mechanism through a transmission rod; the elastic energy storage part is arranged between the impact generation mechanism and the inner wall of the first cavity and interacts with the impact generation mechanism through periodic water impact pulse pressure, so that the impact generation mechanism can generate periodic impact force, the periodic impact force is transmitted to the impact mechanism through the transmission rod, and the impact mechanism and the blade interact to impact and cut mixed rock breaking.

Description

Rock breaking drill bit for downhole drilling tool

Technical Field

The invention belongs to the technical field of tools for oil and gas exploration and development, and particularly relates to a rock breaking drill bit for an underground drilling tool.

Background

The PDC drill bit is widely applied to drilling and development of petroleum and natural gas due to the characteristics of high drilling speed, long service life, flexible design and the like. The conventional PDC drill bit can only cut and break rock at the bottom of a well to form a smooth bottom hole model, cannot form an irregular bottom hole such as a broken pit at the bottom of the well, cannot break the rock in multiple dimensions to release the ground stress in advance, and has low mechanical drilling speed and low drilling efficiency when the drill bit is used in a hard stratum. The impact or extrusion rock breaking mode of the roller cone bit and the mixed bit can improve the mechanical drilling speed and the rock breaking efficiency of the bit to a certain extent, but the bearing in the bit of the type has a large drilling load, so that the bit has short service life and poor safety performance.

Currently, rotary percussion drilling techniques are widely used due to the higher drilling speeds. The rotary impact drilling technology enables the ground stress to be released in advance by pushing the PDC drill bit to impact the stratum to generate an impact crushing pit, so that the difficulty of crushing rocks by the follow-up PDC cutting teeth is reduced, and the comprehensive rock crushing efficiency and the drilling speed of the drill bit are improved. The existing percussion drilling tools include hydraulic jet impactors, hydraulic pulse impactors, torque impactors, composite impactors and the like, and all of the tools are formed by connecting an impact tool to the upper part of a PDC drill bit, so that impact force is applied to the whole drill bit to break a stratum. However, such impact tools have large overall power and large hydraulic energy consumption, and PDC bits connected to these drilling tools have poor impact resistance, so that rock breaking efficiency is improved, and at the same time, cutting teeth of the PDC bits are broken or excessively worn, and the PDC bits fail quickly in a hard formation, thereby seriously affecting drilling construction efficiency and increasing production cost.

Disclosure of Invention

In view of at least some of the above-mentioned technical problems, the present invention proposes a rock breaking drill bit for a downhole drilling tool, which is capable of generating a periodic impact force and of acting on a single tooth of the rock breaking drill bit to provide the rock breaking drill bit with a rock percussive breaking function, so that rock is percussive broken while the drill bit cuts the broken rock. In addition, the rock breaking drill bit can enable the rock breaking teeth to impact the stratum to form an irregular shaft bottom model, and the difficulty of cutting and breaking rock of the blade of the follow-up drill bit is reduced. The rock breaking drill bit can be suitable for deep wells and ultra-deep wells, is high in applicability, and remarkably improves rock breaking efficiency and drilling speed in hard formations.

To this end, according to the present invention, a rock breaking drill bit for a downhole drilling tool is proposed, comprising: the drill bit comprises a drill bit base body, wherein a first cavity extending axially is arranged in the drill bit base body, and a second cavity is arranged in a blade on the drill bit base body; the power mechanism is arranged in the first cavity and comprises an impeller capable of generating rotary power under the action of drilling fluid; the impact generating mechanism is connected to the lower end of the power mechanism and can generate periodic water hammer pulse pressure under the rotation action of the impeller; the impact mechanism is arranged in the second cavity and is connected with the impact generation mechanism through a transmission rod and can reciprocate in the second cavity; wherein impact take place the mechanism with be equipped with elastic energy storage spare between the inner wall of first cavity, elastic energy storage spare with periodic water hammer pulse pressure is right impact takes place the combined action of mechanism, can make impact and take place the mechanism and produce periodic impact force, and will periodic impact force passes through the transfer line transmits for impact mechanism, thereby make impact mechanism with the wing of a knife combined action is strikeed and is cut mixed broken rock.

In a preferred embodiment, the power mechanism comprises a guide wheel for suspending and supporting the impeller, the guide wheel is provided with a plurality of drilling fluid flow passages which are uniformly distributed in the circumferential direction, and the drilling fluid flow passages are configured into arc-shaped through holes which partially extend in the circumferential direction.

In a preferred embodiment, a first shoulder is arranged in the first cavity, and the guide wheel is fixedly mounted on the first shoulder and is in rotational connection with the impeller through a bearing.

In a preferred embodiment, the impact generating mechanism comprises a movable throttle disc fixedly connected with the impeller and a static throttle disc arranged at the downstream end of the movable throttle disc, the movable throttle disc and the static throttle disc rotate relatively under the action of the impeller, so that the flow area of the impact generating mechanism changes periodically to form a throttling effect, periodic water hammer pulse pressure is formed on the static throttle disc, and the static throttle disc reciprocates up and down under the action of the water hammer pulse pressure and the elastic energy storage part to generate periodic impact force.

In a preferred embodiment, the dynamic throttle plate is provided with a first eccentric flow passage, the static throttle plate is provided with a second eccentric flow passage, and the first eccentric flow passage and the second eccentric flow passage are periodically overlapped and staggered under the rotation action of the dynamic throttle plate, so that the flow area of the impact generating mechanism is periodically changed.

In a preferred embodiment, each of the first eccentric flow passage and the second eccentric flow passage is configured to extend partially in a circumferential direction, and an arc angle of the circumferential extension is greater than 180 °.

In a preferred embodiment, a punch hammer is fixedly connected to an end of the static throttle disc opposite to the dynamic throttle disc, and a free end of the punch hammer is configured as a pear-shaped hammer head and is in contact with the transmission rod for transmitting the periodic impact force to the impact mechanism.

In a preferred embodiment, a second shoulder is arranged on the inner wall of the first cavity, one end of the elastic energy storage part is mounted on the second shoulder, and the other end of the elastic energy storage part is in contact with the end face of the static throttle disc.

In a preferred embodiment, the impact mechanism comprises a conical rock breaking tooth and a cylindrical base connected to the end of the conical rock breaking tooth, the diameter of the cylindrical base is set to be larger than that of the conical rock breaking tooth to form a step, and the end face of the cylindrical base is in contact with the end face of the transmission rod.

In a preferred embodiment, an anti-falling ring is fixedly mounted on the inner wall of the second cavity, the conical rock breaking tooth is sleeved in the anti-falling ring, and a return spring is arranged between the anti-falling ring and the step part.

Drawings

The present invention will be described below with reference to the accompanying drawings.

Fig. 1 shows the structure of a rock breaking drill bit for a downhole drilling tool according to the present invention.

Fig. 2 shows the structure of the impeller in the rock breaking drill bit of fig. 1.

Fig. 3 shows the structure of the guide wheel in the rock breaking drill bit of fig. 1.

Fig. 4 shows the construction of the dynamic throttle disc in the rock breaking drill bit of fig. 1.

Fig. 5 is a partially enlarged view of the area a shown in fig. 1.

In the present application, the drawings are all schematic and are used only for illustrating the principles of the invention and are not drawn to scale.

Detailed Description

The invention is described below with reference to the accompanying drawings.

In this application it is to be noted that the end of the wellbore below the rock breaking drill bit for a downhole drilling tool according to the invention remote from the wellhead is defined as the lower end or similar and the end near the wellhead is defined as the upper end or similar.

Fig. 1 shows the structure of a rock breaking drill bit 100 for a downhole drilling tool according to the present invention. As shown in fig. 1, the rock breaking drill bit 100 includes a drill bit base 10. The drilling end of the drill bit base body 10 is provided with a plurality of blades for cutting and breaking rock. The upper end of the drill base 10 is provided with a coupling 11, which coupling 11 is used for mounting the rock breaking drill 100 to an upper drilling tool (not shown). In one embodiment, the coupling 11 is configured as a tapered coupling button to fit with a coupling of an upper drill to fixedly couple the rock breaking drill bit 100 to the upper drill. The joint form of the rock breaking drill bit 100 can ensure the tightness of the connection between the rock breaking drill bit and the upper drilling tool, so that the safety performance of the rock breaking drill bit is ensured, and the rock breaking drill bit is convenient and quick to install.

According to the invention, a first cavity 20 for the arrangement of components is provided in the interior of the drill base body 10. As shown in fig. 1, the first cavity 20 extends axially inward from the upper end face of the drill base 10. The first cavity 20 is configured to include an upper cylindrical cavity portion and a lower cylindrical cavity portion, the diameter of which is set larger than that of the upper cylindrical cavity portion. A first shoulder 21 is provided on the inner wall of the first cylindrical cavity portion in the first cavity 20, and a second shoulder 22 is formed at the junction of the first cylindrical cavity portion and the second cylindrical cavity portion in the first cavity 20. The function of the first and

second shoulders

21, 22 will be described below.

In this embodiment, a second cavity 30 is further provided in the drill base body 10 in communication with the first cavity 20. The second cavity 30 is arranged inside a blade on the rock breaking drill bit 100. According to the invention, a second cavity 30 is provided in the plurality of blades of the rock breaking drill bit 100. As shown in fig. 1, the second cavity 30 is configured as a cylindrical cavity, and the diameter of the second cavity 30 is smaller than that of the cylindrical cavity portion of the first cavity 20. The second cavity 30 is disposed inside the blades to adapt to the distribution of the blades, so that the axis of the second cavity 30 is distributed at an angle to the axial direction of the first cavity 20. One end of the second cavity 30 is communicated with the first cavity 20, and the other end extends to the end of the drill base 10, so that the first cavity 20 and the second cavity 30 jointly penetrate through the drill base 10.

In addition, a flow passage 12 for flowing drilling fluid is arranged inside the drill bit base body 10, and the flow passage 12 is communicated with the rotary cavity part of the first cavity 20 and extends to the tail end of the drill bit base body 10. During operation, drilling fluid from the drilling device is discharged through the first cavity 20 in the drill bit body 10 and further through the flow passage 12.

According to the invention, the rock breaking drill bit 100 further comprises a power mechanism 40. As shown in fig. 1, the power mechanism 40 is disposed within the first cavity 20 and is mounted within the cylindrical cavity portion of the first cavity 20. The power mechanism 40 comprises an impeller 41, and the impeller 41 can rotate under the action of the drilling fluid. Fig. 2 shows the structure of the impeller 41, and as shown in fig. 2, the impeller 41 is constructed in a spiral multi-vane structure. During operation, drilling fluid can flow through the blades to drive the impeller 41 to rotate rapidly.

In this embodiment, the power mechanism 40 further includes a guide wheel 42. The guide wheel 42 is seated on the first shoulder 21 of the first chamber 20 for suspension support of the impeller 41. As shown in fig. 3, guide wheel 42 is configured to be cylindrical. The guide wheel 42 is fixedly mounted on the first shoulder 21 and is fixedly connected to the drill base body 10. A mounting hole 421 axially penetrating the guide wheel 42 is provided in the middle of the guide wheel 42. Meanwhile, a first mounting joint 411 of a cylindrical shape axially outward is provided at one end (upper end in fig. 1) of the impeller 41. The first mounting fitting 411 is fittingly mounted into the mounting hole 421 of the guide wheel 42 through a bearing, so that the impeller 41 is rotatably connected with the guide wheel 42. The guide wheel 42 is provided with a plurality of drilling fluid flow passages 422 which are evenly distributed in the circumferential direction. In one embodiment, the drilling fluid flow passage 422 is configured as an arcuate through bore that extends partially circumferentially. During operation, drilling fluid from the upper drill string passes through the drilling fluid flow passage 422 in the stator 42, thereby driving the impeller 41 to rotate. In one embodiment, the flow passage of the guide wheel 42 may be disposed axially through the guide wheel 42 to form a straight flow passage. In an embodiment not shown, the flow channel of the guide wheel 42 may be configured as a spiral flow channel, and the rotation direction of the flow channel is set to be opposite to the spiral direction of the impeller 41, so that the drilling fluid flow direction can be changed by a large angle to increase the flow channel speed of the drilling fluid, and further, the rotation speed and the rotation power of the impeller can be increased.

According to the invention, the rock breaking drill bit 100 further comprises an impact generating mechanism 50. As shown in fig. 1, the impact generating mechanism 50 is provided at the lower end of the power mechanism 50. The impact generating mechanism 50 includes a dynamic throttle plate 51 and a static throttle plate 52 that are relatively rotatable. The movable throttle disc 51 is fixedly connected with the impeller 41 so as to be capable of synchronously rotating with the impeller 41. The static throttle disc 52 is arranged at the downstream end of the movable throttle disc 51, and during the working process, the static throttle disc 52 does not rotate and can reciprocate up and down relative to the movable throttle disc 51 under the action of drilling fluid.

In the present embodiment, the movable throttle disk 51 is configured in a cylindrical shape. The outer diameter of the movable orifice disc 51 is smaller than the diameter of the cylindrical cavity portion of the first cavity 20. A second mounting tab 511 having a cylindrical shape is provided at a central portion of one end surface of the dynamic throttle plate 51. Meanwhile, the other end (lower end in fig. 1) of the impeller 41 is provided with a first mounting portion 412 extending axially inward. The movable throttle plate 51 is fittingly mounted into the first mounting part 412 of the impeller 41 through the second mounting joint 511, so that the movable throttle plate 51 is fixedly connected with the impeller 41. The movable throttle disk 51 is provided with a first eccentric passage 512 axially penetrating the movable throttle disk 51, and the first eccentric passage 512 is configured to extend partially in the circumferential direction and extend in the circumferential direction at an arc angle of more than 180 °. The static throttle disc 52 is also configured in a cylindrical shape having an outer diameter smaller than the diameter of the cylindrical cavity portion of the first cavity 20, and the static throttle disc 52 is capable of moving up and down in the axial direction of the cylindrical cavity portion of the first cavity 20. The stationary throttle plate 52 is provided with a second eccentric passage 522 axially penetrating the stationary throttle plate 52, the second eccentric passage 522 being configured to extend partially in the circumferential direction, and the circumferentially extending arc angle being greater than 180 °. Fig. 4 schematically shows a three-dimensional structure of the dynamic throttle disk 51.

In operation, the lower end surface of the dynamic throttle disk 51 is in contact with the upper end surface of the static throttle disk 52 in the initial state. And the impeller 41 continuously rotates under the action of the drilling fluid, and the movable throttle disc 51 rotates relative to the static throttle disc 52 along with the synchronous rotation of the impeller 41. The first eccentric flow passage 512 and the second eccentric flow passage 522 are periodically partially overlapped and staggered, and there is always partial overlap to ensure the circulation of the drilling fluid. Thus, the flow area of the impact generating mechanism 50 is periodically changed to generate a throttling effect, so that the drilling fluid generates periodic pulse pressure on the static throttle disc 52.

In the present embodiment, a hammer 53 is also fixedly connected to the lower end of the static throttle disc 52. The lower end surface of the static throttle disc 52 is provided with a second mounting part extending axially inwards, and one end (the upper end in fig. 1) of the impact hammer 53 is fittingly mounted in the second mounting part to form a fixed connection with the static throttle disc 52. The other end (lower end in fig. 1) of the hammer punch 53 is configured as a pear-shaped hammer head. During operation, the hammer 53 moves in synchronization with the static throttle disc 52 and serves to transmit the impact force generated by the static throttle disc 52 to the downstream end.

According to the present invention, the impact generating mechanism 50 further comprises an elastic energy storage member 54, the elastic energy storage member 54 is disposed between the static throttle disc 52 and the inner wall of the first cavity 12, and the inner diameter of the elastic energy storage member 54 is larger than the outer diameter of the impact hammer 53, so that the impact hammer 53 can pass through the elastic energy storage member 54 to be fixedly connected with the static throttle disc 52. In one embodiment, the elastic energy storage member is a disc spring set. The elastic energy storage member 54 is mounted on the second shoulder 22 in the first cavity 20, and one end of the elastic energy storage member 54 is supported on the second shoulder 22, and the other end thereof is in contact with the end surface of the static throttle disc 52 to which the hammer 53 is connected, so as to support the static throttle disc 52. The elastic energy storage member 54 can make the static throttle disc 52 reciprocate under the action of the generated periodic impulse pressure, so as to generate periodic impulse force.

In the actual operation of the impact generating mechanism 50, the impeller 41 rotates under the action of the drilling fluid, and the movable throttle disc 51 rotates relative to the static throttle disc 52 along with the synchronous rotation of the impeller 41. When the movable orifice disc 51 rotates to make the first eccentric flow passage 512 and the second eccentric flow passage 522 intersect and overlap in a small area, the drilling fluid is blocked from flowing and a pulse pressure is generated and applied to the upper end surface of the static orifice disc 52, so that the static orifice disc 52 is pushed downwards to form an impact force. At the same time, the elastic energy storage member 54 is compressed to store energy. When the movable throttle 51 rotates to make the first eccentric flow passage 512 and the second eccentric flow passage 522 overlap in a large area, the drilling fluid flows smoothly and is decompressed. At the same time, the elastic energy storage member 54 is reset and pushes the static throttle disk 52 upward. This causes the static throttle disc 52 to perform a periodic reciprocating motion, thereby generating a periodic impact force.

According to the invention the rock breaking drill bit 100 further comprises a transmission rod 55. As shown in fig. 1, the transmission rod 55 is a cylindrical straight rod which is concentrically installed in the second cavity 30 and can move in the axial direction of the second cavity 30. One end (upper end) of the transmission rod 55 protrudes out of the second chamber 30 to be located in the rotary chamber portion of the first chamber 20, and is in contact with the pear-shaped hammer of the punch 53 connected to the lower end of the static throttle disk 52. The transmission rod 55 is used to transmit the periodic impact force generated by the impact generating mechanism 50.

According to the invention, the rock breaking drill bit 100 further comprises an impact mechanism 60 mounted in the second chamber 30. Fig. 5 is a partially enlarged view of the area a in fig. 1, showing the structure of the impact mechanism 60. As shown in fig. 5, the impact mechanism 60 includes a conical rock breaking tooth 61, a cylindrical base 62 is provided at an end of the conical rock breaking tooth 61, and an end surface of the cylindrical base 62 contacts with an end surface of the transmission rod 55. The cone-shaped rock breaking tooth 61 is used for receiving periodic impact force transmitted by the transmission rod 55 to perform rock breaking drilling. The diameter of the cylindrical base 62 is set to be larger than that of the cone-shaped rock breaking tooth 61, so that a stepped part is formed at the joint of the cylindrical base 62 and the cone-shaped rock breaking tooth 61, and the cone-shaped rock breaking tooth 61 can axially move in the second cavity 30. In addition, a diameter of an end portion of the second cavity 30 adjacent to the first cavity 20 is set smaller than a diameter of an end portion adjacent to the blade of the drill, so that a second shoulder is formed in the second cavity 30. During the installation, the step part of the cylindrical base 62 of the cone-shaped rock breaking tooth 61 is located on the third shoulder, and the step part can limit the axial movement of the cone-shaped rock breaking tooth 61.

In this embodiment, fixed mounting has anti-drop ring 63 on the inner wall of the one end that is close to the drill bit wing of second cavity 30, and anti-drop ring 63 suit is equipped with reset spring 64 between the step portion of anti-drop ring 63 and the broken rock tooth of tapered 61 on the broken rock tooth of tapered 61. One end of the return spring 64 is located on the end face of the anti-falling ring 63, and the other end of the return spring is in contact with the end face of the stepped portion of the conical rock breaking tooth 61 to support the rock breaking tooth 40. The anti-drop ring 63 can compress the return spring 64 and can prevent the cone-shaped rock breaking teeth 61 from dropping off. The cone-shaped rock breaking teeth 61 reciprocate under the combined action of the periodic impact force transmitted by the transmission rod 55 and the return spring 64, so as to generate the periodic impact force, thereby performing impact rock breaking. In addition, broken rock tooth 61 of conical can retract automatically under reset spring 64's effect to can effectively avoid the stratum excessive wear broken rock tooth 61 of conical, effectively prevent that broken rock tooth 61 of conical from becoming invalid prematurely or coming off, prolong broken rock tooth 61's of conical life.

According to the present invention, the transmission rod 55 and the impact mechanism 60 may be respectively installed in the plurality of second cavities 30, so that the impact generation mechanism 50 and the impact hammer 53 impact the plurality of transmission rods and the impact mechanisms at the same time to jointly achieve single-tooth rock breaking, and simultaneously mix with the cutting rock breaking of the drill bit to perform rock breaking drilling, thereby greatly improving the rock breaking efficiency of the rock breaking drill bit 100.

In operation, when the static throttle disc 52 and the hammer 53 of the impact generating mechanism 50 move down to impact the transmission rod 55, the transmission rod 55 moves down to transmit impact force to the conical rock breaking teeth 61, and the conical rock breaking teeth 61 extend outwards to compress the return spring 64. When the impact force disappears, the static throttle disc 52 and the impact hammer 53 move upwards, the return spring 64 pushes the conical rock breaking teeth 61 to retreat, and the conical rock breaking teeth 61 push the transmission rod 55 to move upwards. Thereby, the conical rock breaking tooth 61 completes one rock breaking impact.

The operation of the rock breaking drill bit 100 for a downhole drilling tool according to the present invention is briefly described as follows. During operation of the rock breaking drill bit 100, drilling fluid flows from an upper drilling tool (not shown) into the first cavity 20 of the drill bit base body 10 and flows to the impeller 41 through the drilling fluid flow passage 422 of the guide pulley 42, thereby driving the impeller 41 to rotate at a high speed. The impeller 41 rotates at a high speed and drives the movable throttle disk 51 of the impact generating mechanism 50 to rotate synchronously, while the stationary throttle disk 52 does not rotate. Thus, when the movable orifice disc 51 rotates to overlap the first eccentric flow passage 512 and the second eccentric flow passage 522 to overlap a small area, the flow of the drilling fluid is partially blocked, a large impulsive pressure is instantaneously generated and applied to the upper end surface of the stationary orifice disc 52, thereby pushing the stationary orifice disc 52 and the hammer 53 downward to form an impact force. At the same time, the elastic energy storage member 54 is compressed to be in a contraction power storage state. The hammer punch 53, during the downward movement, strikes and pushes the transmission rod 55 downward, thereby pushing the tapered rock breaking teeth 61 to extend out of the second cavity 30 and generating the rock breaking impact force. Thereby, the impact force of rock breaking is provided to the cone-shaped rock breaking tooth 61 to break rock. At this time, the return spring 64 is in a compressed power storage state. When the impeller 21 rotates continuously, and the movable throttle 51 rotates to make the first eccentric flow passage 512 and the second eccentric flow passage 522 overlap in a large area, the drilling fluid flows smoothly and is decompressed, and the pulse pressure disappears. At the same time, the elastic energy storage member 54 is reset and pushes the static throttle disk 52 upward. At this time, the downward thrust applied to the transmission rod 55 disappears, and the return spring 64 returns to push the tapered rock breaking tooth 61 to retreat and move the transmission rod 55 upward. In operation, the movable throttle disc 51 is continuously rotated by the drilling fluid, so that the first eccentric flow passage 512 of the movable throttle disc 51 and the second eccentric flow passage 522 of the static throttle disc 52 are periodically staggered and overlapped, thereby generating periodic pulse pressure. The static throttle disc 52 is periodically reciprocated by the elastic energy storage member 54 to generate a periodic impact force, and then the periodic impact force is transmitted to the cone-shaped rock breaking teeth 61 through the hammer punch 53 and the transmission rod 55. Meanwhile, the conical rock breaking teeth 61 periodically extend and retract in the second cavity 30 under the action of the return spring 64, and rock breaking impact force is continuously generated to perform impact rock breaking. Therefore, the stratum is impacted and ploughed by the conical rock breaking teeth 61 to form a breaking pit so as to release the ground stress in advance, so that the cutting impact and single-tooth impact mixed impact rock breaking of the rock breaking drill bit 100 is realized, an irregular shaft bottom model is formed, the PDC blades of the follow-up drilling bit are favorable for cutting and breaking rock, and the rock breaking drilling efficiency of the rock breaking drill bit 100 is greatly improved.

The rock breaking drill bit 100 for the downhole drilling tool can generate periodic impact force and can act on a single drill tooth of the rock breaking drill bit to enable the rock breaking drill bit to have a single-tooth impact rock breaking function, so that rock can be broken by impact while the drill bit cuts the rock, and rock breaking by impact and combined cutting and single-tooth impact rock breaking of the rock breaking drill bit 100 are realized. In addition, the rock breaking drill bit 100 can release the ground stress of the rock at the bottom of the well in advance by impacting the rock breaking through the conical rock breaking teeth 61, and can form an irregular bottom hole model, so that the difficulty of cutting and breaking the rock by a follow-up blade is obviously reduced, and the rock breaking efficiency of the drill bit in a hard stratum is further improved. In addition, the rock breaking drill bit 100 has a simple and compact structure, is easy to install and operate, and has high safety performance and long service life.

Finally, it should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and do not limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the foregoing examples, or that equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A rock breaking drill bit for a downhole drilling tool, comprising:

the drill bit comprises a drill bit base body (10), wherein a first cavity (20) extending axially is arranged in the drill bit base body, a second cavity (30) is arranged in a blade on the drill bit base body, the second cavity is arranged in the blade in a manner of adapting to the distribution of the blade, so that the axis of the second cavity and the axial direction of the first cavity are distributed at a certain angle, one end of the second cavity is communicated with the first cavity, and the other end of the second cavity extends to the end part of the drill bit base body;

the power mechanism (40) is arranged in the first cavity and comprises an impeller (41) capable of generating rotary power under the action of the drilling fluid;

the impact generating mechanism (50) is connected to the lower end of the power mechanism and comprises a movable throttling disc (51) fixedly connected with the impeller and a static throttling disc (52) arranged at the downstream end of the movable throttling disc, and the impact generating mechanism can generate periodic water hammer pulse pressure under the rotation action of the impeller; and

an impact mechanism (60) mounted in the second chamber, the impact mechanism being connected to the impact generating mechanism by a transmission rod (55) and being capable of reciprocating in the second chamber;

the device comprises a static throttling disc, a movable throttling disc, a driving rod, an elastic energy storage piece (54), a second shoulder (22) and a driving rod, wherein one end of the static throttling disc, opposite to the movable throttling disc, is fixedly connected with a punching hammer (53), the free end of the punching hammer is constructed into a pear-shaped hammer head and is in contact with the driving rod, the periodical impact force is transmitted to an impact mechanism, the driving rod is concentrically arranged in the second cavity and can move along the axial direction of the second cavity, one end of the driving rod extends out of the second cavity and is positioned in the rotary cavity part of the first cavity, the elastic energy storage piece (54) is arranged between the impact generation mechanism and the inner wall of the first cavity, the inner wall of the first cavity is provided with the second shoulder (22), one end of the elastic energy storage piece is arranged on the second shoulder, the other end of the elastic energy storage piece is in contact with the end face of the static throttling disc, which is connected with the punching hammer, so as to support the static throttling disc, and the elastic energy storage piece and the impact generation piece and the periodical water impact pulse pressure act on the impact generation mechanism together to enable the impact generation mechanism to generate the periodical impact force to be transmitted to the impact mechanism and the cutting mechanism to be mixed with the blade.

2. A rock drill bit according to claim 1, characterized in that the power mechanism comprises a guide wheel (42) for suspension support of the impeller, the guide wheel being provided with a number of drilling fluid flow channels (422) evenly distributed in the circumferential direction, the drilling fluid flow channels being configured as arc-shaped through holes extending partly in the circumferential direction.

3. A rock breaking drill bit according to claim 2, characterized in that a first shoulder (21) is provided in the first cavity, and the guide wheel is fixedly mounted on the first shoulder and is in rotational connection with the impeller via a bearing.

4. The rock breaking drill bit as claimed in any one of claims 1 to 3, wherein the movable throttle disc rotates relative to the static throttle disc under the action of the impeller, so that the flow area of the impact generating mechanism changes periodically to form a throttling effect, and a periodic water hammer pulse pressure is formed on the static throttle disc, so that the static throttle disc reciprocates up and down under the action of the water hammer pulse pressure and the elastic energy storage member to generate a periodic impact force.

5. A rock breaking drill bit according to claim 4, characterized in that the dynamic throttle plate is provided with a first eccentric flow passage (512), the static throttle plate is provided with a second eccentric flow passage (522), and the first eccentric flow passage and the second eccentric flow passage are periodically overlapped and staggered under the rotation action of the dynamic throttle plate, so that the flow area of the impact generating mechanism is periodically changed.

6. The rock breaking drill bit of claim 5, wherein the first eccentric flow channel and the second eccentric flow channel are each configured to extend partially in a circumferential direction and have a circumferential extension arc angle greater than 180 °.

7. The rock breaking drill bit as claimed in claim 1, characterized in that the impact mechanism comprises a conical rock breaking tooth (61) and a cylindrical base (62) connected to the end of the conical rock breaking tooth, the diameter of the cylindrical base is set to be larger than that of the conical rock breaking tooth to form a step, the end face of the cylindrical base is in contact with the end face of the transmission rod, and the conical rock breaking tooth can extend out of the second cavity under the action of the transmission rod to perform impact rock breaking.

8. The rock breaking drill bit as claimed in claim 7, characterized in that an anti-drop ring (63) is fixedly mounted on the inner wall of the second cavity, the cone-shaped rock breaking teeth are sleeved in the anti-drop ring, a return spring (64) is arranged between the anti-drop ring and the step portion, and the cone-shaped rock breaking teeth can retract into the second cavity under the action of the return spring.