CN115874915A

CN115874915A - Self-adaptive screw drill

Info

Publication number: CN115874915A
Application number: CN202111148357.0A
Authority: CN
Inventors: 玄令超; 王甲昌; 张海平; 张仁龙; 孙峰; 陶兴华; 刘晓丹; 胡彦峰; 索忠伟
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: 2021-09-29
Filing date: 2021-09-29
Publication date: 2023-03-31

Abstract

The invention provides a self-adaptive screw drill, which comprises: a cylindrical housing; the power main shaft is used for connecting a power motor, the power main shaft is concentrically arranged in the cylindrical shell and can rotate relative to the cylindrical shell, and the power main shaft is provided with a first central flow passage; the output main shaft is used for connecting a drill bit, the output main shaft is arranged at the lower end of the power main shaft and is provided with a second central flow channel extending along the axial direction, and an elastic part is sleeved on the output main shaft; the power main shaft is constructed to drive the output main shaft to rotate so as to transmit power of the power motor to the drill bit, the output main shaft can move upwards relative to the power main shaft when the torque of the drill bit is too large so as to reduce the soil depth of the drill bit, pressure pulses can be generated when the output main shaft moves upwards to the highest point, meanwhile, the output main shaft compresses the elastic piece to store energy in the ascending process, and elastic potential energy can be released after the elastic piece reaches the highest point, so that the output main shaft impacts the drill bit under the combined action of the pulse pressure and the elastic piece.

Description

Self-adaptive screw drill

Technical Field

The invention belongs to the technical field of drilling tools, and particularly relates to a self-adaptive screw drilling tool.

Background

With continuous exploitation of oil and gas fields, oil and gas exploration gradually advances to a deep layer, the proportion of complex strata and difficult-to-drill strata is increased, the rock breaking difficulty is increased, and the requirements of oil and gas well engineering on drilling speed increasing technologies and tools are more urgent. In order to meet the construction requirements in difficult formations, many acceleration tools based on screw drilling tools have emerged.

At present, most of the speed-up drilling tools use a screw or a turbine and other rotary power sources to drive a hammer to generate impact load by using the difference of the rotating speed between a stator and a rotor. However, the prior art accelerated drilling tools still have some problems. For example, most of the speed-up drilling tools have a single function, sacrifice the rotating speed of a screw drill and only realize axial impact, and have low mechanical drilling speed and low drilling efficiency. In addition, when the drill meets a hard stratum or the depth of penetration of the drill is large, the torque of the drill is too large, so that the underground power motor generates a stagnation phenomenon, even the underground motor is damaged, the efficiency of drilling operation is seriously influenced, and the application range of the speed-up drilling tool is small.

Disclosure of Invention

In view of the above technical problems, the present invention is directed to a self-adaptive screw drill, which can adaptively retract a drill when a torque of the drill is too large, so as to reduce a depth of penetration of the drill and reduce the torque of the drill, thereby preventing a motor from generating a drag phenomenon in a well, and generating a pulse pressure to impact the drill, which is very advantageous for improving a drilling operation efficiency.

To this end, according to the present invention, there is provided an adaptive screw drill comprising: a cylindrical housing; the power main shaft is used for connecting a power motor, the power main shaft is concentrically arranged in the cylindrical shell and can rotate relative to the cylindrical shell, and the power main shaft is provided with a first central flow passage; the output main shaft is used for connecting a drill bit, the output main shaft is arranged at the lower end of the power main shaft and is provided with a second central flow passage extending along the axial direction, and an elastic part is sleeved on the output main shaft; the power main shaft is configured to drive the output main shaft to rotate so as to transmit power of the power motor to a drill bit, the output main shaft can move upwards relative to the power main shaft when torque of the drill bit is too large so as to reduce soil depth of the drill bit, pressure pulses can be generated when the output main shaft moves upwards to the highest point, meanwhile, the output main shaft compresses the elastic part in the ascending process to store energy, and elastic potential energy can be released after the elastic part reaches the highest point, so that the output main shaft impacts the drill bit under the combined action of the pulse pressure and the elastic part.

In one embodiment, a helical spline extending along the axial part is arranged on the outer wall surface of the output main shaft, a helical spline groove capable of being matched with the helical spline is arranged on the inner wall surface of the power main shaft, the output main shaft and the power main shaft are connected with the helical spline groove through the helical spline,

the helical spline is capable of being screwed upwardly relative to the helical spline groove to move the output spindle upwardly relative to the power spindle.

In one embodiment, the pitch of the helical spline is set in the range of 100-800mm, and the helix angle of the helix formed by the helical extension of the helical spline is in the range of 5-85 degrees.

In one embodiment, the helical splines are provided with a width in the range of 40-200mm and a depth in the range of 5-20 mm.

In one embodiment, a first eccentric hole communicated with the first central channel is arranged in the power main shaft, the first eccentric hole is located at the axial inner end of the spiral spline groove, a second eccentric hole communicated with the second central channel is arranged at the upper end of the output main shaft, and the first eccentric hole and the second eccentric through hole are overlapped to form throttling when the output main shaft moves upwards to the highest point, so that pressure pulse is generated.

In one embodiment, an annular limiting groove is formed in the outer surface of the output main shaft, a through hole is formed in the side wall of the power main shaft, a limiting block is installed in the through hole, the axial inner end of the limiting block extends into the annular limiting groove,

the axial width of the annular limiting groove is larger than that of the limiting block.

In one embodiment, the cylindrical housing is configured to include an upper shell, a middle joint, and a lower shell fixedly connected in sequence from top to bottom.

In one embodiment, a bearing string is sleeved on the power main shaft, the bearing string is arranged between the upper shell and the power main shaft, and a first anti-wear assembly and a second anti-wear assembly are respectively arranged at two ends of the bearing string.

In one embodiment, an adjusting retainer ring and a limiting member are respectively arranged at two ends of the elastic member, an upper end surface of the adjusting retainer ring is in contact with a lower end surface of the power main shaft, the limiting member is fixedly connected with the output main shaft,

the output main shaft compresses the elastic part through the limiting part in the upward movement process relative to the power main shaft.

In one embodiment, a limiting cylinder is fixed at the lower end of the lower shell, and a centering wear-resistant assembly is arranged between the limiting cylinder and the output spindle.

Compared with the prior art, the method has the advantages that:

the self-adaptive screw drill tool can adapt to underground working conditions and automatically adjust when the torque of the drill bit is too large, can rotate for a certain distance relative to the power main shaft to move upwards under the matching action of the spiral spline and the spiral spline of the output main shaft, and compresses the elastic part to store energy so as to reduce the soil depth of the drill bit. On the one hand, bit torque is reduced by reducing bit penetration. On the other hand, the output main shaft moves upwards relative to the power main shaft, and pressure pulses are generated when the output main shaft moves upwards to the highest point, so that the generated pressure pulses act on the output main shaft and are further transmitted to the drill bit, the impact force of the drill bit is enhanced, meanwhile, the elastic part is compressed by the output main shaft in the ascending process to store energy, and elastic potential energy is released after the output main shaft ascends to the highest point. Therefore, the phenomenon of stagnation of the underground motor can be effectively prevented. And the output main shaft can impact the drill bit under the combined action of the pulse pressure and the elastic piece, so that the underground working performance of the self-adaptive screw drilling tool is greatly improved, the drilling operation efficiency is greatly improved, and the drilling construction effect is obviously enhanced. In addition, the self-adaptive screw drill is convenient to operate, can self-adapt to the actual working condition in the well in the working process, is automatically adjusted, and has strong adaptability.

Drawings

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

Fig. 1 shows the structure of an adaptive screw drill according to the present invention.

Fig. 2 schematically shows the structure of the helical spline on the output spindle.

Fig. 3 schematically shows the structure of the helical spline grooves on the power spindle.

Fig. 4 schematically shows the distribution structure of the first eccentric holes on the power main shaft and the second eccentric holes on the output main shaft.

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 should be noted that the end of the adaptive screw drill according to the invention lowered into the wellbore close to the wellhead is defined as the upper end or the like, and the end away from the wellhead is defined as the lower end or the like.

Fig. 1 shows the structure of an adaptive screw drill 100 according to the present invention. As shown in fig. 1, the adaptive screw drill 100 includes a cylindrical housing 1, a power spindle 2 concentrically arranged within the cylindrical housing 1, and an output spindle 4 for connecting a drill bit. The power main shaft 2 is concentrically arranged inside the cylindrical shell 1, and a first central flow passage 21 extending along the axial direction is arranged in the power main shaft 2 and used for flowing drilling fluid. The power main shaft 2 is sleeved with a bearing string 3, so that the power main shaft 2 and the cylindrical shell 1 form rotary connection. The output spindle 4 is concentrically arranged in the cylindrical shell 1 and is arranged at the lower end of the power spindle 2, the output spindle 4 is provided with a second central flow passage 41 extending along the axial direction, and an elastic piece 5 is sleeved on the output spindle 4.

In practice, the adaptive progressive cavity drill 100 is mounted at the lower end of a downhole power motor (not shown). When the underground power motor is in work, the underground power motor drives the power spindle 2 to rotate, the power spindle 2 is constructed to be capable of driving the output spindle 4 to rotate so as to transmit the power of the underground power motor to a drill bit, the output spindle 4 can move upwards relative to the power spindle 2 when the torque of the drill bit is too large so as to reduce the soil depth of the drill bit, pressure pulses can be generated when the output spindle 4 moves upwards to the highest point, meanwhile, the output spindle 4 compresses the elastic piece 5 to store energy in the ascending process, and elastic potential energy can be released after the elastic potential energy reaches the highest point, so that the output spindle 4 impacts the drill bit under the combined action of the pulse pressure and the elastic piece.

According to the present invention, as shown in fig. 1, the cylindrical case 1 is configured to include an upper case 11, a middle joint 12, and a lower case 13 fixedly connected in this order from top to bottom. The power main shaft 2 is correspondingly arranged in the upper shell 11 and the middle joint 12, and the output main shaft 4 is correspondingly arranged in the lower shell 13. The middle joint 12 may be a centralizer (helical centralizer or straight edge centralizer), so that the middle joint 12 can centralize the adaptive screw drill 100, which is very beneficial to enhancing the performance of the adaptive screw drill 100.

In one embodiment, the upper housing 11, the middle joint 12 and the lower housing 13 are all fixedly connected by positive and negative tapered connecting buckles. The connection mode is convenient and quick to install, and the connection stability can be effectively guaranteed.

As shown in fig. 1, the bearing string 3 is disposed between the power spindle 2 and the upper housing 11. Preferably, the bearing string 3 is a TC bearing string, which may be, for example, a cemented carbide bearing or a tungsten carbide bearing, wherein TC refers to tungsten carbide, which is the main raw material for producing cemented carbide. The inner ring of the bearing string 3 is in interference fit with the power spindle 2 to form fixed connection, and the outer ring of the bearing string 3 is in fixed connection with the inner wall of the upper shell 11. The power spindle 2 is thereby rotationally connected to the tubular housing 1 via the bearing train 3.

According to the present invention, a first wear assembly 31 and a second wear assembly 32 are provided at the upper and lower ends of the bearing string 3, respectively. As shown in fig. 1, a first wear assembly 31 is located radially between the power spindle 2 and the upper housing 11. The first wear assembly 31 includes a first wear stationary ring 311 and a first wear moving ring 312. The first anti-abrasion static ring 311 is fixedly connected with the inner wall of the upper shell 11, and the lower end face of the first anti-abrasion static ring 311 abuts against the upper end face of the outer ring of the pressing bearing string 3. In one embodiment, the inner wall of the upper housing 11 is provided with a secondary step with a downward end face, the outer wall of the first anti-wear static ring 311 is provided with a secondary step with an upward end face, and the first anti-wear static ring 311 and the upper housing 11 are installed in a matching manner through the secondary steps to form axial limitation. The first anti-wear ring 312 is fixedly connected with the power spindle 2, and the lower end surface of the first anti-wear ring 312 abuts against the upper end surface of the inner ring of the hold-down bearing string 3. The first wear assembly 31 is effective in preventing wear between the power spindle 2 and the upper housing 11.

As shown in fig. 1, a tightening nut 9 is provided at the upper end of the first wear assembly 31, and the tightening nut 9 is fastened to the power spindle 2 by a screw. The tightening nut 9 is used for locking the first anti-wear ring 312 of the first anti-wear assembly 31 on the power spindle 2, so that the first anti-wear ring 312 and the power spindle 2 are relatively static, and the first anti-wear ring 312 and the power spindle 2 are fixedly connected, thereby enhancing the stability of the self-adaptive screw drill 100.

In addition, an adjusting pad can be installed at the upper end of the tightening nut 9 and used as an adjusting piece during installation, so that installation is facilitated.

As shown in fig. 1, the second wear assembly 32 is radially inward of the middle sub 12. The second wear assembly 32 includes a second wear stationary ring 321 and a second wear moving ring 322. The second wear-proof stationary ring 321 forms a fixed connection with the inner wall of the middle joint 12, and the upper end surface of the second wear-proof stationary ring 321 abuts against the lower end surface of the outer ring of the hold-down bearing string 3. In one embodiment, the inner wall of the middle joint 12 is provided with a step with an upward end surface, and the lower end surface of the second wear-resistant stationary ring 321 abuts against the step to form an axial limit. The second anti-wear ring 322 is fixedly connected with the power spindle 2, and the upper end surface of the second anti-wear ring 322 abuts against the lower end surface of the inner ring of the hold-down bearing string 3. The second wear assembly 32 is effective in preventing wear between the power spindle 2 and the middle joint 12.

During operation, the first and

second wear assemblies

31, 32 are able to carry the radial forces generated by the eccentric motion of the rotor in the downhole motor, as well as the oscillation of the cardan shaft body and the fixed-axis rotation of the power spindle 2 itself. Thereby, the guiding ability of the adaptive screw drill 100 and the transmission performance of the power spindle 2 are improved.

According to the present invention, a tightening assembly may also be provided between the bearing string 3 and the second wear assembly 32. As shown in fig. 1, the tightening assembly is disposed between the bearing string 3 and the second wear prevention assembly 32 in the axial direction, and includes an outer tightening sleeve 33 and an inner tightening sleeve 34. The outer jacking sleeve 33 is used for jacking the lower end face of the outer ring of the bearing string 3, and the inner jacking sleeve 34 is used for jacking the lower end face of the inner ring of the bearing string 3. In one embodiment, the inner clamping sleeve 34 is provided with an internal thread, which forms a fixed connection with the power spindle 2 via the internal thread, thereby clamping the inner ring of the bearing string 3, so that the bearing string 3 is axially limited.

According to the present invention, as shown in fig. 1 to 3, a helical spline 42 extending along an axial portion is provided on an outer wall surface of the output spindle 4, a helical spline groove 22 capable of fitting the helical spline 42 is provided on an inner wall surface of the power spindle 2, and the output spindle 4 and the power spindle 2 are connected to the helical spline groove 22 via the helical spline 42. Helical spline 42 can be screwed up relative to helical spline 22 so that output spindle 4 can move up relative to power spindle 2. Thereby, on the one hand, the output spindle 4 can transmit torque through the helical spline 42 and the helically splined groove 22, and on the other hand, the output spindle 4 can move upward or downward relative to the power spindle 2 by the action of the helical spline 42 and the helically splined groove 22.

In one embodiment, for a 7 "drill, the pitch of the helical splines 42 is set to be in the range of 100-800mm and the helix angle of the helix formed by the helical extension of the helical splines 42 is set to be in the range of 5-85 degrees. The helical splines 42 are provided with a width in the range of 40-200mm and a depth in the range of 5-20 mm. Accordingly, the helically splined slot 22 is fitted with the helically splined 42. In order to facilitate the engagement of the helical spline 42 with the helical spline groove 22, the width and depth of the helical spline groove 22 are set to be slightly larger than those of the helical spline 42.

According to the invention, a first eccentric bore 211 (see fig. 4) is provided in the power spindle 2, which first eccentric bore 211 is in communication with the first central passage 21, the first eccentric bore 211 being at the most axial inner end of the helically splined groove 22. Meanwhile, a second eccentric hole 411 (see fig. 4) communicating with the second center flow path 41 is provided at the upper end of the output spindle 4. Before the output main shaft 4 moves upwards to the highest point, the first central channel 21 is communicated with the second central flow channel 41 sequentially through the first eccentric hole 211 and the second eccentric hole 411, at the moment, a certain distance is reserved between the axial end face position provided with the first eccentric hole 211 and the axial end face position provided with the second eccentric hole 411, and the first eccentric hole 211 is in a full-open state. When the output spindle 4 moves upward to the highest point, the axial end face position provided with the first eccentric hole 211 coincides with the axial end face position provided with the second eccentric hole 411, the overlapping area of the first eccentric hole 211 and the second eccentric hole 411 is the smallest, the first central channel 21 is communicated with the second central flow passage 41 through the overlapping area of the first eccentric hole 211 and the second eccentric hole 411, and throttling is formed due to the reduction of the area of the overlapping area, so that pressure pulse is generated. The generated pulse pressure can act on the upper end surface of the output main shaft 4 and then is transmitted to the drill bit, so that axial impact can be formed on the drill bit, the impact force of the drill bit can be enhanced very well, and the brick drilling construction can be improved.

As shown in fig. 1 to 3, an annular limiting groove 43 is provided on the outer surface of the output main shaft 4, a through hole 23 is provided on the sidewall of the power main shaft 2, a limiting block 6 is installed in the through hole 23, and an axial inner end of the limiting block 6 extends into the annular limiting groove 43. In the process of entering the well, the self-adaptive screw drilling tool 100 has the advantages that the limiting block 6 can play a good anti-falling role, and the output main shaft 4 is effectively prevented from falling.

When the stopper 6 is installed, it passes through the through-hole 23 from the outside to the inside from the through-hole 23 and is inserted into the annular stopper groove 43. In order to avoid that the limiting block 6 falls out during operation, a sleeve (not shown) is sleeved on the position, corresponding to the through hole 23, of the power main shaft 2

In this embodiment, the axial width of the annular stopper groove 43 is larger than the axial width of the stopper 6. Moreover, the value obtained by subtracting the axial width of the limiting block 6 from the width of the annular limiting groove 43 is greater than the maximum value of the stroke of the output main shaft 4 capable of moving axially relative to the power main shaft 2, so as to ensure that the position of the axial end face provided with the first eccentric hole 211 can coincide with the position of the axial end face provided with the second eccentric hole 411 when the output main shaft 4 moves upwards to the highest point.

According to the invention, the output spindle 4 is arranged concentrically inside the lower housing 13. The elastic piece 5 is sleeved on the output spindle 4 and is positioned between the lower shell 13 and the output spindle 4 in the radial direction. As shown in fig. 1, a stopper ring 51 and a stopper nut 52 are provided at both ends of the elastic member 5, respectively. The upper end surface of the adjusting retainer ring 51 is in contact with the lower end surface of the power main shaft 2 and is used for adjusting the pretightening force of the elastic piece 5. In one embodiment, a gasket may be provided between the adjustment collar 51 and the resilient member 5. The limiting member 52 is fixedly connected to the output spindle 4. Preferably, the limiting member 52 is fixedly connected with the output spindle 4 through a screw thread, so as to axially limit the elastic member 5. During the upward movement of the output shaft 4 relative to the power shaft 2, the elastic element 5 is compressed by the stop element 52, so that the elastic element 5 is charged. The elastic member 5 may be, for example, a disc spring. In the actual construction process, when the torque of the drill bit is too large, the output main shaft 4 can be screwed for a certain distance relative to the power main shaft 2 to move upwards under the matching action of the helical spline 42 and the helical spline groove 22, so that the elastic part 5 is compressed to store energy, and the phenomenon of hysteresis of the downhole motor can be effectively prevented.

As shown in fig. 1, a stopper tube 7 is fixed to the lower end of the lower case 13. In one embodiment, the limiting cylinder 7 is fixedly connected with the lower shell 13 through threads. A righting anti-wear component 8 is arranged between the limiting cylinder 7 and the output main shaft 4. The centralizing anti-abrasion assembly 8 comprises a centralizing anti-abrasion movable ring and a centralizing anti-abrasion static ring formed on the inner wall of the limiting cylinder 7. The centering anti-wear ring is fixedly connected with the output spindle 4, for example, by a thread. Wear between the output spindle 4 and the lower housing 13 is thereby effectively prevented by the centralising wear assembly 8.

The operation of the adaptive screw drill 100 according to the present invention is briefly described as follows. Firstly, the self-adaptive screw drilling tool 100 is connected to the lower end of the underground motor, the self-adaptive screw drilling tool is put into a shaft after being assembled, and the output main shaft 4 can be effectively prevented from falling under the action of the limiting block 6 and the limiting cylinder 7 in the process of putting into the shaft. The adaptive screw drilling tool 100 is started when it is lowered to a predetermined position downhole. Under normal working conditions, the power spindle 2 is driven by the downhole power motor to rotate, and the power spindle 2 drives the output spindle 4 to rotate through the cooperation of the helical spline 42 and the helical spline groove 22, so that the power of the downhole power motor is transmitted to the drill bit. When the torque of the drill bit is too large, the output main shaft 4 can adapt to the automatic adjustment of the underground working condition, can be screwed for a certain distance relative to the power main shaft 2 to move upwards under the matching action of the helical spline 42 and the helical spline groove 22, and compresses the elastic part 5 to store energy so as to reduce the soil depth of the drill bit. Thus, in the first aspect, the bit torque is reduced by reducing the bit depth of cut. In a second aspect, the output spindle 4 moves upward relative to the power spindle 2, and when the output spindle 4 moves upward to a highest point, a pressure pulse is generated, so that the generated pressure pulse acts on the output spindle 4 and is further transmitted to the drill bit, thereby enhancing the impact force of the drill bit, and meanwhile, the elastic piece 5 is compressed by the output spindle 4 in an upward process to store energy, and elastic potential energy is released after the output spindle 4 moves upward to the highest point. Thereby, the output spindle 4 is caused to impact the drill bit under the combined action of the pulse pressure and the elastic member 5. This is very useful for improving the downhole working performance of the adaptive screw drill 100, greatly improving the drilling construction efficiency, and significantly enhancing the drilling construction effect.

The self-adaptive screw drill 100 can adapt to the underground working condition and automatically adjust when the torque of the drill bit is too large, can rotate for a certain distance relative to the power spindle 2 to move upwards through the matching action of the spiral spline 42 and the spiral spline groove 22 of the output spindle 4, and compresses the elastic piece 5 to store energy so as to reduce the soil depth of the drill bit. In one aspect, bit torque is reduced by reducing bit depth of penetration. And the other is that the output main shaft 4 moves upwards relative to the power main shaft 2, and pressure pulses are generated when the output main shaft 4 moves upwards to the highest point, so that the generated pressure pulses act on the output main shaft 4 and are further transmitted to the drill bit, thereby enhancing the impact force of the drill bit, and meanwhile, the elastic part 5 is compressed by the output main shaft 4 in the process of going upwards to store energy, and elastic potential energy is released after the output main shaft 4 goes upwards to the highest point. Therefore, the phenomenon of stagnation of the underground motor can be effectively prevented. And the output main shaft 4 can impact the drill bit under the combined action of the pulse pressure and the elastic part 5, so that the underground working performance of the self-adaptive screw drilling tool 100 is greatly improved, the drilling construction efficiency is greatly improved, and the drilling construction effect is obviously enhanced. In addition, the self-adaptive screw drill 100 is convenient to operate, can self-adapt to the actual working condition in the well in the working process, is automatically adjusted, and has strong adaptability.

In the description of the present invention, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to imply that the number of technical features indicated is significant. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

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. An adaptive screw drill, comprising:

a cylindrical case (1);

a power spindle (2) for connection to a power motor, the power spindle being concentrically arranged within the cylindrical housing and being rotatable relative to the cylindrical housing, the power spindle being provided with a first central flow channel (21) extending in an axial direction;

the output main shaft (4) is used for connecting a drill bit, the output main shaft is arranged at the lower end of the power main shaft and is provided with a second central flow passage (41) extending along the axial direction, and an elastic part (5) is sleeved on the output main shaft;

the power main shaft is configured to drive the output main shaft to rotate so as to transmit power of the power motor to the drill bit, the output main shaft can move upwards relative to the power main shaft when the torque of the drill bit is too large so as to reduce the soil-eating depth of the drill bit, and can generate pressure pulses when the output main shaft moves upwards to the highest point, meanwhile, the output main shaft compresses the elastic piece to store energy in the ascending process, and can release elastic potential energy after reaching the highest point, so that the output main shaft can impact the drill bit under the combined action of the pulse pressure and the elastic piece.

2. The adaptive screw drill according to claim 1, wherein a helical spline (42) extending along an axial portion is provided on an outer wall surface of the output spindle, a helical spline groove (22) adapted to the helical spline is provided on an inner wall surface of the power spindle, the output spindle and the power spindle are connected to the helical spline groove through the helical spline,

3. The adaptive screw drill according to claim 2, wherein the pitch of the helical spline is set in the range of 100-800mm, and the helix angle of the helix formed by the helical spline extending helically is in the range of 5-85 degrees.

4. An adaptive screw drill according to claim 2 or 3, wherein the helical splines are provided with a width in the range 40-200mm and a depth in the range 5-20 mm.

5. An adaptive screw drill according to claim 2 or 3, wherein a first eccentric hole (211) is provided in the power spindle and communicates with the first central passage, the first eccentric hole is located at the axially inner end of the helical spline groove, a second eccentric hole (411) is provided at the upper end of the output spindle and communicates with the second central flow passage, and the first eccentric hole and the second eccentric through hole overlap to form a throttle when the output spindle moves upwards to the highest point, thereby generating a pressure pulse.

6. The adaptive screw drill according to claim 1, wherein an annular limiting groove (43) is provided on the outer surface of the output spindle, a through hole (23) is provided on the sidewall of the power spindle, a limiting block (6) is installed in the through hole, the axially inner end of the limiting block extends into the annular limiting groove,

the axial width of the annular limiting groove is larger than the width of the limiting block.

7. The adaptive screw drill according to claim 1, wherein the cylindrical housing is configured to include an upper housing (11), a middle joint (12) and a lower housing (13) fixedly connected in this order from top to bottom.

8. The adaptive screw drill according to claim 7, wherein a bearing string (3) is sleeved on the power spindle, the bearing string is arranged between the upper housing and the power spindle, and a first anti-wear assembly (31) and a second anti-wear assembly (32) are respectively arranged at two ends of the bearing string.

9. The adaptive screw drill according to claim 7, wherein an adjusting retainer ring (51) and a limiting member (52) are respectively arranged at two ends of the elastic member, an upper end surface of the adjusting retainer ring is in contact with a lower end surface of the power spindle, the limiting member is fixedly connected with the output spindle,

10. The adaptive screw drill according to claim 9, characterized in that a limiting cylinder (7) is fixed at the lower end of the lower housing, and a centralizing anti-wear assembly (8) is provided between the limiting cylinder and the output spindle.