Lifting device and rotary drilling rig

Abstract

The present invention discloses a lifting device and a rotary drilling rig, relating to the technical field of engineering machinery. The lifting device is arranged on the rotary drilling rig and includes a pulley assembly, a winch, and a wire rope extending from the winch. The pulley assembly includes a movable pulley, a large pulley, and a fixed pulley respectively arranged on the mast of the rotary drilling rig. The fixed pulley is located between the large pulley and the movable pulley. The wire rope passes through the large pulley, the movable pulley, and the fixed pulley in sequence and is connected to a power head. The movable pulley is used to connect to the power head of the rotary drilling rig and drive the power head to move via the wire rope. There are three force application points between the wire rope and the power head. Three sections of wire rope apply tension to the power head at the three force application points, respectively, so that the lifting force of the wire rope is three times the lifting force. This solves the technical problem that there is no rotary drilling rig with a wire rope lifting force of three times the lifting force in the prior art. At the same time, the lifting mechanism can reduce the tensile strength requirements of a single wire rope while ensuring the tension of the wire rope.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering machinery, and in particular to a lifting device and a rotary drilling rig. Background Art

[0002] A rotary drilling rig is a construction machine suitable for drilling holes in building foundation projects. It is mainly suitable for construction in sandy soil, clay soil, silty soil and other soil layers. It is widely used in various foundation construction projects such as cast-in-place piles, continuous walls, and foundation reinforcement.

[0003] Wire rope is a critical consumable material during the operation of rotary drilling rigs and a crucial component in ensuring safe production. Currently, common wire rope lifting capacities for rotary drilling rigs are 1x or 4x, but not 3x. However, in practice, there is still a need for rotary drilling rigs with wire ropes capable of 3x. Summary of the Invention

[0004] The object of the present invention is to provide a lifting device and a rotary drilling rig to solve the technical problem in the prior art that the rotary drilling rig cannot achieve a 3-fold lifting rate of the wire rope.

[0005] The embodiment of the present invention is achieved as follows:

[0006] According to one aspect of an embodiment of the present invention, a lifting device is provided, which is arranged on a rotary drilling rig and includes a pulley assembly, a winch and a wire rope extending from the winch. The pulley assembly includes a movable pulley, and a large pulley and a fixed pulley respectively arranged on the mast of the rotary drilling rig. The fixed pulley is located between the large pulley and the movable pulley. The wire rope passes through the large pulley, the movable pulley and the fixed pulley in sequence and is connected to the power head of the rotary drilling rig. The movable pulley is used to connect to the power head of the rotary drilling rig and drive the power head to move through the wire rope.

[0007] In an optional embodiment of the present invention, the above-mentioned large pulley is rotatably connected to the mast through a pulley frame, the pulley frame and the mast are at a preset angle and form an accommodating space, the mounting frame of the fixed pulley extends into the accommodating space and is respectively fixed to the pulley frame and the mast, and the fixed pulley is located outside the accommodating space.

[0008] In an optional embodiment of the present invention, the preset angle is 15° to 60°.

[0009] In an optional embodiment of the present invention, the mounting frame includes an upper rib plate and a lower rib plate, and an angle between the upper rib plate and the lower rib plate is equal to a preset angle.

[0010] In an optional embodiment of the present invention, the upper rib plate and the pulley frame are correspondingly provided with a first mounting hole, and the first connecting member connects the upper rib plate to the pulley frame through the first mounting hole, and the lower rib plate and the mast are correspondingly provided with a second mounting hole, and the second connecting member connects the lower rib plate to the mast through the second mounting hole.

[0011] In an optional embodiment of the present invention, the above-mentioned large pulley includes a first large pulley and a second large pulley, the first large pulley and the second large pulley are located in the same plane, and the wire rope passes around the first large pulley and the second large pulley in sequence.

[0012] In an optional embodiment of the present invention, the movable pulley, the first large pulley and the second large pulley are located in the same plane.

[0013] In an optional embodiment of the present invention, the plane where the fixed pulley is located is perpendicular to the plane where the movable pulley is located.

[0014] In an optional embodiment of the present invention, a hook is provided at one end of the steel wire rope extending out of the winch.

[0015] Another aspect of an embodiment of the present invention provides a rotary drilling rig, which includes a mast, a power head and a lifting device of any one of the above items, the lifting device includes a large pulley and a fixed pulley, the large pulley and the fixed pulley are respectively connected to the mast, the power head is located on the side of the mast, and the movable pulley is connected to the power head.

[0016] The beneficial effects of the embodiments of the present invention include:

[0017] This embodiment provides a lifting device, mounted on a rotary drilling rig, for lifting the power head of the rotary drilling rig. The lifting device includes a pulley assembly, a winch, and a wire rope extending from the winch. One end of the wire rope is connected to the winch, and the other end passes through the pulley assembly and is connected to the power head of the rotary drilling rig. The winch winds the wire rope around a drum, thereby lifting the power head. The pulley assembly includes a movable pulley, a large pulley, and a fixed pulley, respectively, mounted on the mast of the rotary drilling rig. The fixed pulley is located between the large pulley and the movable pulley. The wire rope passes through the large pulley, the movable pulley, and the fixed pulley in sequence before connecting to the power head. The movable pulley is connected to the power head of the rotary drilling rig and drives the power head via the wire rope. The wire rope passes through the movable pulley, forming two force application points between the wire rope and the power head via the movable pulley. The two sections of wire rope each apply tension to the power head via the movable pulley. After the wire rope finally passes through the fixed pulley, its end is connected to the power head, forming a third force application point. The above-mentioned wire rope winding method is different from other common wire rope winding methods in the prior art. There are three force application points between the wire rope and the power head. The three sections of wire rope apply tension to the power head at the three force application points respectively. The tension on the wire rope is only one-third of the gravity on the power head, that is, the lifting force of the wire rope is 3 times, which solves the technical problem that there is no rotary drilling rig with a wire rope lifting force of 3 times in the prior art. At the same time, the lifting mechanism can reduce the requirements for the tensile strength of a single wire rope while ensuring the tension of the wire rope. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a schematic diagram of the structure of a lifting device provided in an embodiment of the present invention;

[0020] Figure 2 The second structural diagram of the lifting device provided by the embodiment of the present invention;

[0021] Figure 3 This is a schematic structural diagram of a fixed pulley in a lifting device provided by an embodiment of the present invention.

[0022] Icons: 100-lifting device; 110-wire rope; 120-movable pulley; 130-large pulley; 131-first large pulley; 132-second large pulley; 140-fixed pulley; 150-pulley frame; 160-mounting frame; 161-upper rib plate; 162-lower rib plate; 163-first mounting hole; 200-mast. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] In the description of the present invention, it should be noted that the terms "inside" and "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The terms "setting" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] A rotary drilling rig is a construction machine suitable for drilling holes in building foundations. In the prior art, common rotary drilling rigs have wire rope lift forces of 1x or 4x, but not 3x. However, in practical applications, there is still a need for rotary drilling rigs with a wire rope lift force of 3x.

[0026] Figure 1 This is one of the structural diagrams of the lifting device provided in the embodiment of the present invention, please refer to Figure 1This embodiment provides a lifting device 100, which is installed on a rotary drilling rig and is used to lift the power head of the rotary drilling rig. The lifting device 100 includes a pulley assembly, a winch, and a wire rope 110 extending from the winch. One end of the wire rope 110 is connected to the winch, and the other end passes through the pulley assembly and is connected to the power head of the rotary drilling rig. The winch uses a drum to wind the wire rope 110, thereby lifting the power head. The pulley assembly includes a movable pulley 120, a large pulley 130 and a fixed pulley 140, which are respectively installed on the mast 200 of the rotary drilling rig. The fixed pulley 140 is located between the large pulley 130 and the movable pulley 120. The wire rope 110 passes through the large pulley 130, the movable pulley 120, and the fixed pulley 140 in sequence before being connected to the power head. The movable pulley 120 is connected to the power head of the rotary drilling rig and drives the power head through the wire rope 110. The wire rope 110 passes around the movable pulley 120, forming two force application points between the wire rope 110 and the power head via the movable pulley 120. The two sections of wire rope 110 respectively apply tension to the power head via the movable pulley 120. After the wire rope 110 finally passes around the fixed pulley 140, its end is connected to the power head of the rotary drilling rig, forming a third force application point. The above-mentioned wire rope 110 winding method is different from other common wire rope 110 winding methods in the prior art, so that there are three force application points between the wire rope 110 and the power head. The three sections of wire rope 110 apply tension to the power head at the three force application points respectively. The tension on the wire rope 110 is only one-third of the gravity on the power head, that is, the lifting force of the wire rope 110 is 3 times, which solves the technical problem that there is no rotary drilling rig with a lifting force of the wire rope 110 of 3 times in the prior art. At the same time, the lifting mechanism can reduce the requirements for the tensile strength of a single wire rope 110 while ensuring the tension of the wire rope 110.

[0027] It should be noted that, first, there is no restriction on the connection method between the large pulley 130 and the fixed pulley 140 and the mast 200. They can be connected directly or through other parts, as long as the large pulley 130 and the fixed pulley 140 can rotate under the drive of the wire rope 110. Second, there is no restriction on the connection method between the movable pulley 120 and the power head of the rotary drilling rig. They can be connected directly or through other parts, as long as the movable pulley 120 can rotate under the drive of the wire rope 110. Third, there is no restriction on the connection method between the end of the wire rope 110 and the power head. They can be connected directly or through other parts, and can be fixed or detachable. Fourth, there is no restriction on the size and material of the large pulley 130, movable pulley 120, fixed pulley 140 and wire rope 110, but they must ensure sufficient strength.

[0028] In any of the above technical solutions, the large pulley 130 is optionally rotatably connected to the mast 200 via a pulley frame 150. The pulley frame 150 and the mast 200 are arranged at a predetermined angle to form a receiving space. The mounting bracket 160 of the fixed pulley 140 extends into the receiving space and is fixed to the pulley frame 150 and the mast 200, respectively. Furthermore, to avoid affecting the winding and movement of the wire rope 110, the fixed pulley 140 is located outside the receiving space. The lifting force of the wire rope 110 in the above-described lifting device 100 has two magnifications: 3 and 1.

[0029] For example, a pin hole is provided on the pulley frame 150 , and correspondingly, a pin hole is also provided on the mast 200 . The pin shaft connects the pulley frame 150 and the mast 200 through the pin hole, so that the pulley frame 150 can rotate around the mast 200 .

[0030] Please refer to Figure 1 The large pulley 130 is rotatably connected to the mast 200 through the pulley frame 150. When the lifting force of the wire rope 110 is required to be 3 times, the pulley frame 150 is rotated so that the pulley frame 150 and the mast 200 are at a preset angle and form an accommodating space. Then, the mounting frame 160 of the fixed pulley 140 is extended into the accommodating space and fixed to the pulley frame 150 and the mast 200 respectively. At this time, the pulley assembly includes a movable pulley 120, a large pulley 130 and a fixed pulley 140. The wire rope 110 passes around the large pulley 130, the movable pulley 120 and the fixed pulley 140 in sequence. There are three force application points between the wire rope 110 and the power head, namely two force application points formed by the wire rope 110 passing through the movable pulley 120 and one force application point formed by the wire rope 110 being directly connected to the power head. The three sections of wire rope 110 apply tension to the power head at the three force application points respectively. The tension on the wire rope 110 is only one-third of the gravity on the power head, that is, the lifting force of the wire rope 110 is 3 times.

[0031] Figure 2 For the second structural diagram of the lifting device provided by the embodiment of the present invention, please refer to Figure 2 When the lifting force of the wire rope 110 needs to be changed to a 1-fold ratio, the fixing between the mounting bracket 160 of the fixed pulley 140 and the pulley frame 150 and the mast 200 is released, the mounting bracket 160 of the fixed pulley 140 is removed, and the pulley frame 150 is driven to rotate toward the mast 200 so that the above-mentioned accommodation space no longer exists between the pulley frame 150 and the mast 200. Then, the pulley frame 150 is fixed to the mast 200, and at the same time, the movable pulley 120 connected to the power head is removed. At this time, the pulley assembly only includes the large pulley 130. The wire rope 110 is directly connected to the power head after passing around the large pulley 130. There is only one force application point between the wire rope 110 and the power head. The tension on the wire rope 110 is equal to the gravity on the power head, that is, the lifting force of the wire rope 110 is a 1-fold ratio.

[0032] The lifting force of the wire rope 110 in the above-mentioned lifting device 100 can be freely switched between 3 times and 1 times, which can realize both the 3-times CFA method (Continuous Flight Auger long spiral drilling into pipe pumping concrete pouring pile construction) and the standard rotary drilling rig method (i.e. 1-times CFA method). One device has two uses and has great market competitiveness.

[0033] In any of the above technical solutions, optionally, the preset angle is 15° to 60°.

[0034] The preset angle is 15° to 60°, which ensures the strength of the mounting frame 160 while facilitating the connection between the mounting frame 160, the pulley frame 150, and the mast 200. If the preset angle is too small, the accommodation space formed by the pulley frame 150 and the mast 200 is also small. To fit within this accommodation space and be secured, the mounting frame 160 is smaller, resulting in a lower strength and difficulty in securing the mounting frame 160. If the preset angle is too large, the pulley frame 150 will tilt too much, hindering the securement of the pulley frame 150 itself and the securement between the pulley frame 150, the mast 200, and the mounting frame 160.

[0035] Figure 3 For a structural diagram of a fixed pulley in a lifting device according to an embodiment of the present invention, please refer to Figure 3 In any of the above technical solutions, optionally, the mounting frame 160 includes an upper rib plate 161 and a lower rib plate 162, and the angle between the upper rib plate 161 and the lower rib plate 162 is equal to a preset angle, so that the mounting frame 160 just extends into the accommodation space formed by the pulley frame and the mast 200 and is easy to fix without swinging.

[0036] It should be noted that there is no limitation on the connection method between the upper rib plate 161 and the lower rib plate 162. They can be connected through connectors or directly welded, as long as the angle between the upper rib plate 161 and the lower rib plate 162 remains unchanged and equal to the preset angle.

[0037] In any of the above technical solutions, optionally, a first mounting hole 163 is correspondingly provided on the upper rib plate 161 and the pulley frame 150, and the first connecting member connects the upper rib plate 161 to the pulley frame 150 through the first mounting hole 163, and a second mounting hole is correspondingly provided on the lower rib plate 162 and the mast 200, and the second connecting member connects the lower rib plate 162 to the mast 200 through the second mounting hole.

[0038] For example, the first mounting hole 163 and the second mounting hole are both through holes, the first connecting member includes a first bolt and a first nut, and the second connecting member includes a second bolt and a second nut; after the first bolt passes through the first mounting hole 163 on the upper rib plate 161 and the pulley frame in sequence, it is threadedly engaged with the first nut to fix the upper rib plate 161 to the pulley frame 150; after the second bolt passes through the second mounting hole on the lower rib plate 162 and the mast 200 in sequence, it is threadedly engaged with the second nut to fix the lower rib plate 162 to the mast 200; in order to improve the strength of the connection, there can be multiple first mounting holes 163 and second mounting holes, and multiple first mounting holes 163 and multiple second mounting holes can be used to achieve multiple fixations.

[0039] In order to make the steel wire rope 110 smoothly avoid the interference of the mast 200, avoid the oversize of the large pulley 130 simultaneously, in any of the above technical solutions, optionally, the large pulley 130 includes a first large pulley 131 and a second large pulley 132, and the first large pulley 131 and the second large pulley 132 are located in the same plane, and the steel wire rope 110 passes around the first large pulley 131 and the second large pulley 132 in sequence. By controlling the installation distance between the first large pulley 131 and the second large pulley 132, the two ends of the steel wire rope 110 passing around the first large pulley 131 and the second large pulley 132 are located on both sides of the mast 200 and do not interfere with the mast 200. Compared to only arranging a single large pulley 130, arranging two large pulleys 130 (i.e., the first large pulley 131 and the second large pulley 132) can reduce the size of the large pulley 130, not only can reduce costs, but also facilitate installation.

[0040] For example, the bottom surface of the pulley frame 150 is connected to the mast 200, and the first large pulley 131 and the second large pulley 132 are respectively installed at the two ends of the top surface opposite to the bottom surface. The length of the top surface in the winding direction of the wire rope 110 is greater than the length of the mast 200 in this direction. After the wire rope 110 extends from the winch, it passes around the first large pulley 131 and the second large pulley 132 in sequence. The wire rope 110 at both ends of the first large pulley 131 and the second large pulley 132 are respectively located on both sides of the mast 200. Therefore, the wire rope 110 will not interfere with the mast 200. The first large pulley 131 and the second large pulley 132 are located in the same plane, so that the wire rope 110 will not deflect during the winding process, which can reduce the obstruction of the first large pulley 131 and the second large pulley 132 to the reciprocating motion of the wire rope 110.

[0041] After the steel wire rope 110 passes around the second large pulley 132, it will continue to pass around the movable pulley 120. Similarly, in order to reduce the obstruction of the movable pulley 120 to the reciprocating motion of the steel wire rope 110, in any of the above technical solutions, optionally, the movable pulley 120 is located in the same plane as the first large pulley 131 and the second large pulley 132, thereby ensuring that the steel wire rope 110 located between the first large pulley 131 and the movable pulley 120 is always located in the same plane, which can reduce the resistance to the steel wire rope 110 and make the movement of the steel wire rope 110 more stable. At the same time, it also makes the component of the pulling force provided by the steel wire rope 110 to the power head in the direction of the gravity of the power head greater, and under the premise that the pulling force provided by the steel wire rope 110 remains unchanged, a heavier power head can be lifted.

[0042] After the wire rope 110 passes around the movable pulley 120, it continues to pass around the fixed pulley 140 and is then connected to the power head. In order to reduce the obstruction of the fixed pulley 140 to the reciprocating motion of the wire rope 110 and improve the effect of the tension of the wire rope 110, in any of the above technical solutions, optionally, the plane where the fixed pulley 140 is located is perpendicular to the plane where the movable pulley 120 is located.

[0043] There are many ways to connect the wire rope 110 to the power head. In any of the above technical solutions, optionally, a hook is provided at one end of the wire rope 110 extending out of the winch.

[0044] For example, a hook is provided at one end of the wire rope 110 extending from the winch. Correspondingly, a lifting eye is provided on the power head that mates with the hook. The hook is attached to the lifting eye, securing the wire rope 110 to the power head. The hook comprises a fixed portion and a movable portion, which together form a closed ring. The movable portion is rotatably connected to the fixed portion. To release the connection between the wire rope 110 and the power head, the movable portion is rotated to release the lifting eye from the hook.

[0045] The working principle of the lifting device 100 is:

[0046] The lifting device 100 is installed on a rotary drilling rig and is used to raise the drilling rig's power head. The lifting device 100 includes a pulley assembly, a winch, and a wire rope 110 extending from the winch. One end of the wire rope 110 is connected to the winch, and the other end passes through the pulley assembly and is connected to the drilling rig's power head. The winch reel winds the wire rope 110, thereby raising the power head. The pulley assembly includes a movable pulley 120, a large pulley 130, and a fixed pulley 140, respectively, which are installed on the drilling rig's mast 200. The fixed pulley 140 is located between the large pulley 130 and the movable pulley 120. The wire rope 110 passes through the large pulley 130, the movable pulley 120, and the fixed pulley 140 in sequence. The movable pulley 120 is used to connect with the power head of the rotary drilling rig and drive the power head to move through the wire rope 110. The wire rope 110 passes around the movable pulley 120 so that two force application points are formed between the wire rope 110 and the power head by relying on the movable pulley 120. The two sections of wire rope 110 respectively apply tension to the power head by relying on the movable pulley 120. After the wire rope 110 finally passes around the fixed pulley 140, its end is connected to the power head to form the third force application point. At this time, there are three force application points between the wire rope 110 and the power head. The three sections of wire rope 110 apply tension to the power head at the three force application points respectively. The tension on the wire rope 110 is only one-third of the gravity on the power head, that is, the lifting force of the wire rope 110 is 3 times, which solves the technical problem that there is no rotary drilling rig with a lifting force of 3 times the wire rope 110 in the prior art. At the same time, the lifting mechanism can reduce the requirements for the tensile strength of a single wire rope 110 while ensuring the tension of the wire rope 110.

[0047] This embodiment also provides a rotary drilling rig, comprising a mast 200, a power head, and any of the aforementioned lifting devices 100. The lifting device 100 includes a large pulley 130 and a fixed pulley 140, each of which is connected to the mast 200. The power head is located to the side of the mast 200, and the movable pulley 120 is connected to the power head. The rotary drilling rig can implement a 3x CFA method and has low requirements for the tensile strength of a single steel wire rope 110. In addition, the rotary drilling rig can freely switch between the CFA method and the standard rotary drilling method, achieving dual-purpose use in one machine, which is highly competitive in the market.

[0048] For example, the mast 200 is vertically mounted, with the large pulley 130 positioned at the top of the mast 200. The movable pulley 120 is connected to the power unit and is positioned on the same side of the mast 200 as the fixed pulley 140, with the fixed pulley 140 positioned between the large pulley 130 and the movable pulley 120. After extending from the winch, the wire rope 110 sequentially winds around the large pulley 130, the movable pulley 120, and the fixed pulley 140 before connecting to the power unit. This method for winding the wire rope 110 differs from other common winding methods for wire ropes 110 in the prior art and enables the implementation of a three-rate CFA method.

[0049] When the rotary drilling rig's power head needs to be raised, the winch winds up the wire rope 110, shortening the length of the wire rope 110 wrapped around the pulley assembly. This shortens the lengths of the three sections of wire rope 110 that apply tension to the power head. The movable pulley 120 moves upward under the action of the wire rope 110, thereby driving the power head upward. Simultaneously, the end of the wire rope 110 also pulls the power head upward. The three sections of wire rope 110 apply tension to the power head at three points of application, simultaneously pulling the power head upward.

[0050] When the power head of the rotary drilling rig needs to be lowered, the winch unwinds the wire rope 110, lengthening the wire rope 110 wound around the pulley assembly. This means that all three sections of wire rope 110 exerting tension on the power head are also lengthened. The movable pulley 120 moves downward under the action of the wire rope 110, thereby driving the power head downward. Simultaneously, the end of the wire rope 110 also drives the power head downward.

[0051] The tension on the wire rope 110 in the rotary drilling rig is only one-third of the gravity on the power head, that is, the lifting force of the wire rope 110 is 3 times, which solves the technical problem that there is no rotary drilling rig in the prior art with a wire rope 110 lifting force of 3 times. At the same time, the lifting mechanism can reduce the requirement for the tensile strength of a single wire rope 110 while ensuring the tension of the wire rope 110.

[0052] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A lifting device, provided on a rotary drilling rig, characterized in that: The invention comprises a pulley assembly, a winch and a steel wire rope extending from the winch, wherein the pulley assembly comprises a movable pulley, and a large pulley and a fixed pulley respectively arranged on the mast of the rotary drilling rig, the fixed pulley being located between the large pulley and the movable pulley, the steel wire rope being connected to the power head of the rotary drilling rig after passing through the large pulley, the movable pulley and the fixed pulley in sequence, and the movable pulley being used to connect to the power head and drive the power head to move through the steel wire rope; The steel wire rope passes around the movable pulley so that two force application points are formed between the steel wire rope and the power head by means of the movable pulley, and the two sections of the steel wire rope respectively apply tension to the power head by means of the movable pulley; after the steel wire rope finally passes around the fixed pulley, its end is connected to the power head of the rotary drilling rig, forming a third force application point; The large pulley includes a first large pulley and a second large pulley, the first large pulley and the second large pulley are located in the same plane, and the wire rope passes around the first large pulley and the second large pulley in sequence; The movable pulley, the first large pulley and the second large pulley are located in the same plane; the plane where the fixed pulley is located is perpendicular to the plane where the movable pulley is located.

2. The lifting device according to claim 1, characterized in that The large pulley is rotatably connected to the mast through a pulley frame. The pulley frame and the mast are at a preset angle and form a receiving space. The mounting frame of the fixed pulley extends into the receiving space and is fixed to the pulley frame and the mast respectively. The fixed pulley is located outside the receiving space.

3. The lifting device according to claim 2, characterized in that The preset angle is 15° to 60°.

4. The lifting device according to claim 2, characterized in that The mounting frame includes an upper rib plate and a lower rib plate, and an angle between the upper rib plate and the lower rib plate is equal to the preset angle.

5. The lifting device according to claim 4, characterized in that The upper rib plate and the pulley frame are correspondingly provided with first mounting holes, and the first connecting member connects the upper rib plate to the pulley frame through the first mounting hole. The lower rib plate and the mast are correspondingly provided with second mounting holes, and the second connecting member connects the lower rib plate to the mast through the second mounting hole.

6. The lifting device according to claim 1, characterized in that One end of the steel wire rope extending out of the winch is provided with a hook.

7. A rotary drilling rig, characterized in that: It comprises a mast, a power head and a lifting device according to any one of claims 1 to 6, wherein the lifting device comprises a large pulley and a fixed pulley, the large pulley and the fixed pulley are respectively connected to the mast, the power head is located on the side of the mast, and the movable pulley is connected to the power head.

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