CN114837549A

CN114837549A - Screw drill

Info

Publication number: CN114837549A
Application number: CN202110145214.8A
Authority: CN
Inventors: 任宪可; 王春阳; 李明谦; 李连强; 郝健
Original assignee: BOHAI PETROLEUM EQUIPMENT (TIANJIN) ZHONGCHENG MACHINERY MANUFACTURING CO LTD; China National Petroleum Corp; CNPC Bohai Equipment Manufacturing Co Ltd
Current assignee: BOHAI PETROLEUM EQUIPMENT (TIANJIN) ZHONGCHENG MACHINERY MANUFACTURING CO LTD; China National Petroleum Corp; CNPC Bohai Equipment Manufacturing Co Ltd
Priority date: 2021-02-02
Filing date: 2021-02-02
Publication date: 2022-08-02

Abstract

The application discloses a screw drill, which belongs to the field of petroleum drilling and workover, wherein one end of a bypass valve assembly in the screw drill is connected with one end of an anti-falling assembly; the anti-drop assembly comprises an anti-drop short circuit and an anti-drop pull rod positioned in the anti-drop short circuit; the stator in the motor assembly comprises a stator pipe and a right-handed spiral rubber bushing positioned in the stator pipe, the right rotator is positioned in the stator pipe, one end of the right rotator is in threaded connection with one end of the anti-falling pull rod through right-handed threads, and the stator pipe is in threaded connection with the anti-falling short joint through left-handed threads; one end of a universal shaft in the universal shaft assembly is connected with one end of the right rotator, and the universal shaft shell is connected with the stator tube; one end of a transmission shaft in the transmission shaft assembly is connected with the other end of the universal shaft, and the other end of the transmission shaft is used for being connected with the drill bit. The problem of the junction of each subassembly of screw rod drilling tool among the correlation technique is easily not hard up is solved, the effect of the fastening nature between each subassembly of screw rod drilling tool has been reached.

Description

Screw drill

Technical Field

The application relates to the field of oil drilling and workover, in particular to a screw drilling tool.

Background

When crude oil, natural gas or underground deposits deeply buried in a formation are produced, mechanical equipment is used to drill the formation into a cylindrical bore hole having a certain depth, which is a drilling hole in oil production operations. One well drilling method commonly used is rotary drilling, where rock is broken up by the cutting or grinding action produced by the rotation of the drill bit. The screw drilling tool is a positive displacement type underground power drilling tool which takes drilling fluid as power and converts liquid pressure energy into mechanical energy, and the screw drilling tool is connected with a drill bit, so that the drilling speed of the drill bit can be improved.

A screw drilling tool in the related art comprises a bypass valve assembly, an anti-drop assembly, a motor assembly, a universal shaft assembly and a transmission shaft assembly, wherein the transmission shaft is coaxially connected with a drill bit. When the screw motor is in work, media such as slurry, clear water and the like are injected into the screw motor, so that the screw motor drives the universal shaft and the transmission shaft to further rotate the drill bit, and the purpose of converting liquid pressure energy into mechanical energy is achieved.

However, in the above-mentioned related art screw drill, the joints of the respective components are easily loosened during use.

Disclosure of Invention

The embodiment of the application provides a screw drill. The technical scheme is as follows:

in a first aspect, a screw drill is provided, the screw drill comprising a bypass valve assembly, an anti-drop assembly, a motor assembly, a cardan shaft assembly and a transmission shaft assembly;

one end of the bypass valve assembly is connected with one end of the anti-falling assembly;

the anti-drop assembly comprises an anti-drop short circuit and an anti-drop pull rod positioned in the anti-drop short circuit;

the motor assembly comprises a stator and a right rotator, the stator comprises a stator pipe and a right-handed spiral rubber bushing positioned in the stator pipe, the right rotator is positioned in the stator pipe, one end of the right rotator is in threaded connection with one end of the anti-falling pull rod through a right-handed thread, and the stator pipe is in threaded connection with the anti-falling short joint through a left-handed thread;

the universal shaft assembly comprises a universal shaft shell and a universal shaft positioned in the universal shaft shell, one end of the universal shaft is connected with one end of the right rotator, and the universal shaft shell is connected with the stator tube;

the transmission shaft assembly comprises a transmission shaft shell and a transmission shaft positioned in the transmission shaft shell, one end of the transmission shaft is connected with the other end of the universal shaft, and the other end of the transmission shaft is used for being connected with a drill bit.

Optionally, the anti-drop assembly further comprises an anti-drop nut and an anti-drop baffle disc, the anti-drop short joint comprises a first pipe section and a second pipe section which are connected, and the inner diameter of the second pipe section is smaller than that of the first pipe section;

the other end of the anti-falling pull rod penetrates through the opening and is sequentially connected with the anti-falling baffle disc and the anti-falling nut through right-handed threads, the outer diameter of the anti-falling baffle disc is larger than the inner diameter of the second pipe section, and the diameter of the anti-falling pull rod is smaller than the inner diameter of the second pipe section.

Optionally, the other end of the drive shaft has a left turn buckle according to the american petroleum institute standard.

Optionally, one end of the bypass valve assembly is in threaded connection with the anti-drop short joint through left-hand threads.

Optionally, the right rotator is formed by machining a disc milling cutter, the included angle direction of the machining axis of the disc milling cutter is opposite to the included angle direction of the machining axis of the left rotator, and the included angle ranges from 5 degrees to 80 degrees.

Optionally, the right-handed spiral rubber bushing in the stator is formed by arranging a mandrel in the stator tube, injecting rubber into the stator tube, and then forming the rubber, wherein the mandrel is formed by machining a disc milling cutter, and the direction of the included angle of the machining axis of the disc milling cutter is the same as the direction and the range of the included angle of the machining axis of the disc milling cutter during machining of the right rotator.

Optionally, the surfaces of the mandrel and the rotor are formed by swinging and processing the surfaces of the mandrel and the rotor along two directions of a included angle of a processing axis through a polishing machine, and the swinging angle is-60 degrees to 60 degrees.

Optionally, the cross-section of the stator has a short hypocycloid equidistant line.

Optionally, the cross section of the right rotor is a conjugate curve of an equidistant line of the short hypocycloid.

Optionally, the anti-falling assembly further comprises a shock-absorbing structure, and the shock-absorbing structure is located on one side of the anti-falling baffle disc facing the rotor.

The technical scheme provided by the embodiment of the application can have the following beneficial effects:

the utility model provides an including the bypass valve subassembly, prevent falling the subassembly, motor element, the screw rod drilling tool of universal shaft subassembly and transmission shaft subassembly, the bypass valve subassembly with prevent falling the subassembly and be connected, the stator passes through left-handed threaded connection and prevents falling short circuit threaded connection, right rotor and stator meshing in the motor element, after power fluid pours into, the rotor is rotatory, the pressure energy with power fluid converts mechanical energy into, the universal shaft subassembly turns into the dead axle of transmission shaft with the eccentric motion of right rotor and rotates back with power transmission to the transmission shaft subassembly, the transmission shaft subassembly is with power transmission to rather than the drill bit of being connected. In the drilling operation, when the reverse drilling is met, the screw drill can rotate anticlockwise, and the left-hand thread connection is screwed more and more tightly in the rotation process of the drill bit. The problem of the junction of each subassembly of screw rod drilling tool among the correlation technique is easily not hard up is solved, the effect of the fastening nature between each subassembly of screw rod drilling tool has been reached.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application.

FIG. 1 is a schematic structural diagram of a screw drill according to an embodiment of the present disclosure;

FIG. 2 is a schematic structural diagram of another screw drill provided in an embodiment of the present application;

FIG. 3 is a partial schematic view of the progressive cavity drill of FIG. 2;

FIG. 4 is a cross-sectional view of the motor assembly of the progressive cavity drill of FIG. 2.

With the above figures, there are shown specific embodiments of the present application, which will be described in more detail below. These drawings and written description are not intended to limit the scope of the inventive concepts in any manner, but rather to illustrate the inventive concepts to those skilled in the art by reference to specific embodiments.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The power liquid of the screw drill can be slurry or clear water, the power liquid is pumped into the screw drill through a slurry pump, the power liquid enters a screw motor through a central hole of a pipe column, the screw motor converts the liquid pressure energy of the power liquid into mechanical energy, the mechanical energy of the motor is transmitted to a drill bit through a transmission shaft, the screw drill is used as a channel for conveying a high-pressure working medium and a rod piece for supporting the counter torque of the drill bit in the process of underground drilling, and the screw drill does not do rotary motion when doing rotary motion.

The rock stratum environment is complicated in the pit, at the in-process of drill bit probing, run into comparatively hard rock layer or when needing to carry out the slope broken rock, the rotary motion of drill bit rotates irregularly, or produce the reversal under the hindrance of hard material, the reversal operation in-process, the reverse force of drill bit is exerted on the screw rod drilling tool, thereby each subassembly in the screw rod drilling tool that leads to being connected with the drill bit is under reverse effort, connecting piece between the subassembly is not hard up, lead to the power transmission ability between the screw rod drilling tool subassembly to weaken, the drilling ability of drill bit reduces behind the power transmission of motor to the drill bit, to originally more difficult broken rock work of just hard rock, need the drilling of suspending, take out the back with the screw rod drilling tool, overhaul and fasten each subassembly.

In addition, the components of the screw drill connected by the drill bit may break and fracture the string of the screw drill under the reverse acting force. The tubular column of screw rod drilling tool can fall into in the pit after the fracture, need suspend the well drilling this moment, use fishing tool in the pit will fall into the broken pit shaft in the rock seam and not hard up the other spare parts of the screw rod drilling tool that falls into thereupon salvage out one by one after, change screw rod drilling tool and drill bit again and carry out the drilling operation, above-mentioned process of salvaging debris in the pit is wasted time and energy, and has increased the drilling cost, has influenced the oil development progress.

The embodiment of the application provides a screw drill, which can solve the problems existing in the related art.

Fig. 1 is a schematic structural diagram of a screw drill according to an embodiment of the present disclosure.

The progressive cavity drill includes a bypass valve assembly 10, a drop prevention assembly 20, a motor assembly 30, a universal shaft assembly 40, and a drive shaft assembly 50.

One end of the bypass valve assembly 10 is connected to one end of the drop prevention assembly 20.

The drop prevention assembly 20 includes a drop prevention short 21 and a drop prevention pull rod 22 located in the drop prevention short 21.

The motor assembly 30 comprises a stator 31 and a right rotator 32, the stator 31 comprises a stator tube 311 and a right-handed spiral rubber bushing 312 positioned inside the stator tube 311, the right rotator 32 is positioned in the stator tube 311, one end of the right rotator 32 is in threaded connection with one end of the anti-falling pull rod 22 through a right-handed thread, and the stator tube 311 is in threaded connection with the anti-falling short joint 21 through a left-handed thread.

The universal shaft assembly 40 includes a universal shaft housing 41 and a universal shaft 42 located in the universal shaft housing 41, one end of the universal shaft 42 is connected to one end of the right rotator 32, and the universal shaft housing 41 is connected to the stator tube 311.

The drive shaft assembly 50 includes a drive shaft housing 51 and a drive shaft 52 located in the drive shaft housing 51, one end of the drive shaft 52 being connected to the other end of the cardan shaft 42, the other end of the drive shaft 52 being adapted for connection to a drill bit.

To sum up, the embodiment of the application provides a screw rod drilling tool including bypass valve subassembly, prevent falling the subassembly, motor element, universal shaft subassembly and transmission shaft subassembly, the bypass valve subassembly with prevent falling the subassembly and be connected, the stator passes through left-handed threaded connection and prevents falling short circuit threaded connection, right rotor and stator meshing in the motor element, after power fluid pours into, the rotor is rotatory, the pressure energy with power fluid converts mechanical energy into, the universal shaft subassembly turns into the dead axle of transmission shaft with the eccentric motion of right rotor and rotates the back with power transmission to transmission shaft subassembly, the transmission shaft subassembly is with power transmission to rather than the drill bit of being connected. In the drilling operation, when the reverse drilling is met, the screw drill can rotate anticlockwise, and the left-hand thread connection is screwed more and more tightly in the rotation process of the drill bit. The problem of the junction of each subassembly of screw rod drilling tool among the correlation technique is easily not hard up is solved, the effect of the fastening nature between each subassembly of screw rod drilling tool has been reached.

Optionally, the right rotator is processed by a disc milling cutter, the direction of the included angle of the processing axis of the disc milling cutter is opposite to the direction of the included angle during processing of the left rotator, and the included angle ranges from 5 degrees to 80 degrees.

Optionally, the right-handed spiral rubber bushing in the stator is formed by rubber after the mandrel is arranged in the stator tube and rubber is injected into the stator tube, the mandrel is processed by a disc milling cutter, and the direction of the included angle of the processing axis of the disc milling cutter is the same as the direction and the range of the included angle of the right rotator during processing.

Optionally, the surfaces of the mandrel and the rotor are machined by swinging of a polishing machine along two directions of a machining axis included angle, and the swinging angle is-60 degrees to 60 degrees.

Optionally, the cross section of the right rotor is a conjugate curve of an equidistant line of a short hypocycloid.

Optionally, the anti-drop assembly further comprises a shock-absorbing structure, and the shock-absorbing structure is located on one side of the anti-drop baffle disc facing the rotor.

Please refer to fig. 2, which shows a schematic structural diagram of another screw drill according to an embodiment of the present application.

Optionally, the other end of the drive shaft 52 has an American Petroleum institute standard left hand clasp 521. The transmission shaft 52 is located in the transmission shaft housing 51, and one end of the transmission shaft 52 is connected to the other end of the universal shaft 42 and receives the force applied by the motor assembly 30 and transmitted by the universal shaft 42. The other end of the transmission shaft 52 is connected with a drill bit (not shown in the figure), the transmission shaft 52 directly transmits the power of the screw drill to the drill bit, therefore, the transmission shaft 52 is an important part in the screw drill, if a common threaded connection buckle is used, in the process of drilling by the drill bit, hard rock stratum is encountered, the rotation motion of the drill bit is irregular, or under the condition that the drill bit generates reverse rotation under the obstruction of hard substances, the other end of the transmission shaft 52 directly receives the reverse rotation force of the drill bit, the other end of the transmission shaft 52 can generate the condition that the screw thread at the other end of the transmission shaft rotates along with the drill bit, and therefore, the screw thread is loose. When the drill bit rotates reversely, the left-handed thread at the other end of the transmission shaft 52 rotates more and more tightly, namely, the connection between the other end of the transmission shaft 52 and the drill bit is firmer and firmer, so that the reduction of the drilling capability of the drill bit or the falling of the drill bit caused by the loosening of the connecting piece is avoided.

The American Petroleum Institute (API) is the major trade-promoting organization for the united states industry, and establishes a number of industry standards and recommendations covering various fields of oil and gas. The left-handed threaded fastener used in the examples of the present application meets the standards set by the American Petroleum institute for left-handed connection threaded fasteners.

The cardan shaft assembly 40 includes a cardan shaft housing 41 and a cardan shaft 42 located in the cardan shaft housing 41. The universal shaft assembly 40 connects the motor assembly 30 and the transmission shaft assembly 50 together, and as a transfer assembly for power transmission, the universal shaft assembly 40 can convert the eccentric motion of the motor assembly 30 into the fixed-shaft rotation of the transmission shaft 52, the universal shaft 42 in the embodiment of the present application is a flexible-shaft type universal shaft, and a petal type universal shaft or a ball-hinged type universal shaft can also be used, and the specific form of the universal shaft is not limited herein.

One end of a universal shaft 42 in the universal shaft assembly 40 is in threaded connection with one end of the right rotor 32 through left-handed threads, the rotation of the drill bit is irregular, or under the condition that the drill bit is reversely rotated due to the obstruction of hard materials, the universal shaft 42 is connected with one end of the right rotor 32 more and more tightly, the threaded connection is firmer, and the weakening of the power transmission of the screw drill caused by the loosening of the connection between the universal shaft assembly 40 of the screw drill and the motor assembly 30 is avoided.

The cardan shaft housing 41 in the cardan shaft assembly 40 is screwed with the stator tube 311 by left-hand threads. Under the condition that the rotation of the drill bit is irregular or the drill bit rotates reversely under the obstruction of hard substances, the universal shaft shell 41 is connected with one end of the stator tube 311 more and more tightly, the threaded connection is firmer, and the power transmission weakening of the screw drill caused by the loose connection between the universal shaft component 40 and the motor component 30 of the screw drill is avoided.

Optionally, one end of the bypass valve assembly 10 is threadedly connected to the anti-short-circuit through left-hand threads. The other end of the bypass valve assembly 10 is connected to a power fluid injection pump (not shown), the bypass valve assembly 10 may include a valve body, a valve sleeve, a valve core and a spring, when power fluid is injected into the screw drill, the valve core slides in the valve sleeve under the action of the fluid pressure, the fluid flow direction of the power fluid can be changed through the sliding motion of the valve core, therefore, the bypass valve assembly 10 is in an open or closed state, that is, during the drill-tripping operation or the drill-down operation, the valve sleeve and the valve body through hole are not closed, the bypass valve assembly is in an open state, when the power fluid is injected, the power fluid can enter the drop prevention assembly 20 through the bypass valve assembly 10, and then enter the motor assembly 30 from the drop prevention assembly 20, the motor assembly 30 converts the pressure energy, when the flow and the pressure of the power fluid reach preset values, the valve core moves downwards, the valve body through hole of the bypass valve assembly 10 is closed, and the bypass valve assembly 10 is in a closed state.

The flow rate of the power fluid injected by the bypass valve assembly 10 is related to the power value generated by the motor assembly 30, when the flow rate of the power fluid is large, the power formed by the motor assembly 30 is larger, so that the power provided for a drill bit is larger, therefore, whether the internal structure of the bypass valve assembly 10 can normally operate is particularly important, before the screw drill provided by the embodiment of the application is used for drilling, whether the power fluid can flow through the bypass valve assembly 10 in the screw drill can be checked, so that the power fluid injected by the bypass valve assembly after the screw drill goes down the well can not normally flow, and the bypass valve assembly can be put into use after being checked to be qualified. In addition, other components capable of improving the performance of the bypass valve assembly and ensuring the flow of the power fluid can be further included in the bypass valve assembly, and the embodiment of the application is not limited again.

Fig. 3 is a partial structural view of the progressive cavity drill of fig. 2, and fig. 3 is a structural view of the motor assembly 30 and the drop prevention assembly 20.

The motor assembly 30 includes a stator 31 and a right rotator 32, the motor assembly 30 is an assembly for providing power to the drill bit, the stator 31 and the right rotator 32 in the motor assembly 30 can be engaged with each other when power fluid is injected, wherein the stator 31 is connected with a sleeve in the motor assembly 30, that is, the stator 31 is generally fixed on the inside of the progressive cavity drill, when the stator 31 and the right rotator 32 are engaged, the stator 31 is in a non-moving state, the right rotator 32 is generally a spiral rod with a spiral structure thereon, when the power fluid is injected, the rotor rotates and is engaged with the stator when rotating, a spiral sealing cavity is formed by using a lead difference between the right rotator 32 and the stator 31, so as to convert the pressure energy of the power fluid into mechanical energy, thereby providing power to the drill bit.

Optionally, the right rotator 32 is formed by machining a disc milling cutter, the included angle direction of the machining axis of the disc milling cutter is opposite to the included angle direction of the machining axis of the left rotator, and the included angle ranges from 5 degrees to 80 degrees. The right rotator 32 is positioned in the stator tube 311, and one end of the right rotator 32 is in threaded connection with one end of the anti-drop pull rod 22 through right-hand threads. The screw rod that a corrosion-resistant and material hardness are high can be selected to right-hand rotary son 32, mills processing to the screw rod, forms right-hand thread, and milling cutter is the rotary cutter who has one or more sword teeth, and wherein disc milling cutter can mill big terminal surface owing to the diameter is great, mills on the screw rod in this application, and the area of milling is great, uses disc milling cutter can increase milling speed. The disc milling cutter can be used on a vertical milling machine, an end face milling machine or a planer type milling machine, and the specific specification and model of the milling machine are not limited in the embodiment of the application.

Because the right rotator 32 in the embodiment of the present application has a different spiral direction from the rotor in the related art, when the right rotator 32 in the embodiment of the present application is manufactured, a milling machine and a disc milling cutter for processing the right rotator are first adjusted, the included angle direction of the processing axis of the disc milling cutter is opposite to the included angle direction when the left rotator is processed, at this time, the milling machine is started, and the disc milling cutter intermittently cuts off the allowance of the screw rod in sequence by each cutter tooth during working, so that the screw rod forms uniformly distributed inclined protrusions and depressions, thereby forming the right rotator 32. The included angle range of the disc milling cutter and the processing axis is 5 degrees to 80 degrees, and the right rotator 32 which is spirally rightward can be processed in the angle range. The helix of the right rotator 32 may comprise a single start or a multiple start helix. The smaller the number of heads of the right rotor 32, the higher the rotation speed, and the smaller the torque; the higher the number of heads, the lower the speed and the higher the torque. In the embodiment of the present application, the number of heads of the right rotator 32 is not limited.

The stator 31 comprises a stator tube 311 and a right-handed spiral rubber bushing 312 positioned inside the stator tube 311, and the stator tube 311 is in threaded connection with the anti-drop short joint 21 through left-handed threaded connection. Wherein the threaded connection of the stator tube 311 and the anti-drop short 21 meets the API standard. In the embodiment of the present application, in order to avoid a situation of a screw drill falling into a well, an anti-falling assembly 20 is further disposed between the bypass valve assembly and the motor assembly, and after the stator tube 311 of the stator 31 is connected to the anti-falling assembly 20, the motor assembly 30 can be prevented from falling into the well when a casing of the screw drill is broken.

Optionally, the right-handed spiral rubber bushing 312 in the stator 31 is formed by disposing a mandrel in the stator tube 311, injecting rubber into the stator tube 311, and cooling the rubber, the mandrel is formed by machining a disc milling cutter, and the direction of the included angle between the machining axis of the disc milling cutter and the direction and the range of the included angle when machining the right rotator are the same. Since the right rotator 32 rotates in the stator 31. The better the fixity of the stator 31, the longer the service life of the motor assembly 30, so in order to avoid the stator 31 falling off caused by the loose fixation of the stator 31 and the screw drill, the rubber injected into the mandrel can be heated to a flowable state, after the mandrel is arranged in the stator pipe 311, the heated flowable rubber is injected into the stator pipe 311, and after the rubber is cooled and formed, the stator 31 firmly connected with the screw drill sleeve can be formed. The mandrel in the stator 31 determines the overall shape of the stator 31, and in order to enable the stator 31 and the right rotator 32 to be tightly engaged, when the mandrel in the stator 31 is manufactured, the included angle direction of the machining axis of the disc milling cutter and the included angle direction of the machining axis of the right rotator are the same, and the included angle range is also the same, the included angle range in the embodiment of the present application is any value from 5 degrees to 80 degrees, and the specific angle value in the embodiment of the present application is not limited herein.

Optionally, the surfaces of the mandrel and the right rotator 32 are formed by swinging and processing the surfaces by a polishing machine along two directions of a processing axis included angle, and the swinging angle is-60 degrees to 60 degrees. Because the surfaces of the spindle and the right rotor 32 after the disc milling cutter is subjected to cutting processing may be rough, when the surface of the spindle is rough, the injected rubber may be cooled to form a rough and uneven surface, so that the meshing and sealing effects of the stator 31 and the right rotor 32 may be affected, and after the disc milling cutter is formed, the surface of the right rotor 32 and the surface of the spindle need to be ground and polished to make the surfaces smooth and flat. In the embodiment of the present application, the polishing machine is used for polishing, the spindle or the right rotator 32 is rotated at a high speed by a sponge or wool polishing disk mounted on the polishing machine, and the polishing disk and the polishing agent cooperate and rub against the spindle or the right rotator 32, so that the contamination and the shallow mark on the surface of the spindle or the right rotator 32 are removed, and the stator 31 and the right rotator 32 can be better engaged.

Fig. 4 is a cross-sectional view of the motor assembly of the progressive cavity drill in fig. 2, during the engagement process of the stator 31 and the right rotator 32, that is, during the rotation process of the right rotator 32 in the stator, the right rotator 32 rotating around the axis has a plurality of engagement points, and the enclosed cavities of the plurality of engagement points can form a sealed cavity, the volume of the sealed cavity is fixed, and the sealed cavity gradually moves along the axis along with the rotation of the right rotator 32 in the stator 21, so that the pressure energy of the power fluid can be converted into mechanical energy. A cross-sectional view between the stator and the right rotator 32 in which the right rotator 32 is rotated to different angles may be as shown in fig. 4.

Alternatively, the cross-section of the stator 31 has a short hypocycloid equidistant line. The short hypocycloid is a locus of a point which is fixedly connected with a moving circle (generating circle) and is positioned in the moving circle when the moving circle (generating circle) rolls along the inner side of a fixed circle (base circle) on a plane. As shown in fig. 4, in cross section, the right rotor 32 rolls along the inside of the stator 31.

Alternatively, the cross section of the right rotor 32 is a conjugate curve of the equidistant lines of the short hypocycloids. The conjugate curve is a pair of curves of two members which are continuously tangent to each other to realize a given motion law, and when the cross section of the stator 31 has an equidistant line of a short hypocycloid, the cross section of the right rotor 32 is the conjugate curve of the equidistant line of the short hypocycloid.

Optionally, the drop-preventing assembly 20 includes a drop-preventing short joint 21 and a drop-preventing pull rod 22 located in the drop-preventing short joint 21, the drop-preventing assembly 20 further includes a drop-preventing nut 23 and a drop-preventing baffle disc 24, the drop-preventing short joint 21 includes a first pipe section 211 and a second pipe section 212 which are connected, and an inner diameter of the second pipe section 212 is smaller than an inner diameter of the first pipe section 211; the other end of the drop-preventing pull rod 22 passes through the opening and is sequentially connected with the drop-preventing baffle disc 24 and the drop-preventing nut 23 through right-handed threads, the outer diameter of the drop-preventing baffle disc 24 is larger than the inner diameter of the second pipe section 212, and the diameter of the drop-preventing pull rod is smaller than the inner diameter of the second pipe section. First pipeline section 211 of anti-falling short circuit 21 is connected with the bypass valve subassembly, when the sleeve of screw rod drilling tool splits, because the one end of anti-falling pull rod 22 is connected with motor element 30, anti-falling fender dish 24 card is in second pipeline section 212, the pulling anti-falling pull rod 22 does not drop downwards, motor element 30 of being connected with the anti-falling pull rod 22 other end can not drop, thereby the universal shaft subassembly of being connected with motor element 30, and the transmission shaft subassembly of being connected with the universal shaft subassembly can not drop to in the well, avoided because spare part falls into in the well and shut down the well and salvage the junk, the performance and the oil development efficiency of screw rod drilling tool have been improved.

Optionally, the anti-drop assembly further comprises a shock-absorbing structure, and the shock-absorbing structure is located on one side of the anti-drop baffle disc facing the rotor. The screw rod drilling tool is usually steel or other alloy materials, exemplarily, the screw rod drilling tool can be tungsten alloy material, therefore the weight of screw rod drilling tool is also heavier, when the sleeve pipe fracture, when motor assembly, universal shaft assembly and drive shaft assembly drop downwards, prevent falling to block the dish and move downwards until the card on second pipeline section 212, motor assembly, universal shaft assembly and drive shaft assembly's weight makes and prevents falling to block and produce a great vibrational force between dish and the second pipeline section 212, shock-absorbing structure can reduce the vibrational force between preventing falling to block dish and the second pipeline section 212, reduce the harm that this vibrational force can avoid screw rod drilling tool when vibrational force produces.

The above description is intended to be exemplary only, and not to limit the present application, and any modifications, equivalents, improvements, etc. made within the spirit and scope of the present application are intended to be included therein.

Claims

1. The screw drill is characterized by comprising a bypass valve assembly, an anti-dropping assembly, a motor assembly, a universal shaft assembly and a transmission shaft assembly;

2. The progressive cavity drill of claim 1 wherein the drop prevention assembly further comprises a drop prevention nut, a drop prevention catch, the drop prevention pup joint comprising a first pipe segment and a second pipe segment connected, the second pipe segment having an inner diameter less than the inner diameter of the first pipe segment;

3. The progressive cavity drill of claim 1 wherein the other end of the drive shaft has an american petroleum institute standard left turn buckle.

4. The progressive cavity drill of claim 1 wherein one end of the bypass valve assembly is threadably connected to the anti-shortcircuit via left-hand threads.

5. The progressive cavity drill of claim 1 wherein the right rotor is machined by a disc cutter having an axis of included angle in a direction opposite to an angle of included angle in machining the left rotor, the included angle ranging from 5 degrees to 80 degrees.

6. The progressive cavity drill of claim 5 wherein the right-handed helical rubber bushing of the stator is formed from rubber after a mandrel is placed in the stator tube and the rubber is injected into the stator tube, the mandrel is machined with a disc cutter, and the included angle between the machining axis of the disc cutter and the included angle of the right rotor is the same in both direction and extent.

7. The progressive cavity drill of claim 6 wherein the surfaces of the mandrel and the rotor are machined by a polisher by swinging in both directions at an angle between the machining axes, the angle of swinging being-60 degrees to 60 degrees.

8. The progressive cavity drill of claim 1 wherein the cross-section of the stator has a short hypocycloid equidistant line.

9. The progressive cavity drill of claim 7 wherein the cross-section of the right rotor is a conjugate of the equidistant lines of the short hypocycloids.

10. The progressive cavity drill of claim 2 wherein the anti-dropout assembly further comprises a shock absorbing structure located on a side of the anti-dropout disc facing the rotor.