A dual-purpose reverse circulation drilling rig for down-the-hole drilling

Abstract

The application relates to a dual-purpose reverse circulation drilling machine of a down-the-hole drill, and relates to the field of reverse circulation drilling machines, which comprises a drilling machine body, a drill rod arranged on one side of the drilling machine body and a drill bit arranged on the drill rod, further comprises a reaming assembly, a casing assembly and a transmission part. The reaming assembly is used for changing the drilling diameter of the drill bit; the casing assembly is used for supporting the well casing installed in the well; and the transmission part is used for driving the casing assembly to be separated from the well casing after the drilling is completed. Through cooperation of the reaming assembly, the casing assembly and the transmission part, the drilling machine body can adapt to the change of the well diameter during the drilling process, and the applicability is wider.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of reverse circulation drilling machines, in particular to a dual-purpose reverse circulation drilling machine for pipe lowering. BACKGROUND

[0002] A drilling machine is a mechanical device used in exploration, earthwork or mineral resource development operations, which drives a drilling tool into the ground to break the rock at the bottom of the hole. The existing drilling machine is composed of a lifting system, a rotating system, a circulating system, a power system, a transmission system, a control system, a base and other auxiliary equipment. The reverse circulation drilling machine protects the drilling through the circulation of drilling fluid and brings the drilling cuttings out of the drilling. The drilling fluid is delivered into the drilling from the wellhead (the outside of the drill pipe) by a mud pump, and then extracted from the middle of the drill pipe by compressed air or a mud pump. The reverse circulation drilling machine has strong cuttings removal capacity and performs well in drilling in formations with large particles such as gravel layers.

[0003] The reverse circulation drilling machine in the related art has the functions of drilling and pipe lowering. After drilling is completed, the reverse circulation drilling machine does not need to use a crane to hoist and place the well pipe into the drilling, and has wide applicability.

[0004] For the related art described above, the inventors believe that for drilling with special requirements, such as changing the diameter of the drilling hole to a specified depth, the drill pipe needs to be lifted to replace the drill bit, and then drilling is performed again. After drilling is completed, the drill pipe is lifted again to support the well pipe, and then the well pipe is installed into the drilling. At this time, the reverse circulation drilling machine cannot perform drilling and pipe lowering operations simultaneously. SUMMARY

[0005] In order to adapt to the situation where the diameter of the pipe well needs to be changed during drilling, the present application provides a dual-purpose reverse circulation drilling machine for pipe lowering.

[0006] The present application provides a dual-purpose reverse circulation drilling machine for pipe lowering, which adopts the following technical solution:

[0007] A dual-purpose reverse circulation drilling machine for pipe lowering, comprising a drilling machine body, a drill pipe arranged on one side of the drilling machine body, and a drill bit arranged on the drill pipe, further comprising:

[0008] A reaming assembly for changing the drilling diameter of the drill bit;

[0009] A pipe lowering assembly for supporting the well pipe installed in the drilling;

[0010] A transmission member for driving the pipe lowering assembly to disengage from the well pipe after drilling is completed.

[0011] By adopting the technical scheme, the reaming assembly can change the drilling diameter of the drill bit, the downpipe assembly supports the well pipe to be installed in the well after drilling is completed, the transmission member drives the downpipe assembly to be separated from the well pipe after downpipe is completed, the drilling machine body can still drill and downpipe simultaneously in the case of changing the drilling diameter during drilling, and the adaptability is wider.

[0012] Optionally, the reaming assembly comprises a reaming rod arranged on the side wall of the drill bit and a hinge shaft for mounting the reaming rod, the reaming rod is rotationally connected to the outer side wall of the drill bit through the hinge shaft, and the reaming assembly further comprises a first electric telescopic rod arranged in the drill bit, and the end of the movable end of the first electric telescopic rod is slidably connected with the reaming rod.

[0013] By adopting the technical scheme, the first electric telescopic rod can control the rotation angle of the reaming rod through the telescopic degree of the movable end, that is, the drilling diameter of the drill bit can be changed, and the operation is convenient and fast.

[0014] Optionally, the reaming rod and the hinge shaft are symmetrically arranged in two groups on the outer side wall of the drill bit, the first electric telescopic rod is a bidirectional telescopic rod structure, and the ends of the two movable ends of the first electric telescopic rod are slidably connected with the corresponding reaming rods respectively.

[0015] By adopting the technical scheme, the arrangement of the two groups of reaming rods makes the drill bit more stable during drilling.

[0016] Optionally, a connecting groove is arranged on the side wall of the well pipe, a clamping groove is arranged on the side wall of the connecting groove, the downpipe assembly comprises a second telescopic rod vertically arranged on one side of the drill bit, the movable end of the second telescopic rod is arranged opposite to the connecting groove, an installation groove is arranged on the movable end of the second telescopic rod, and an elastic member for clamping the well pipe is arranged in the installation groove.

[0017] By adopting the technical scheme, when the well pipe is connected, the elastic member is used to clamp the well pipe, and the installation and dismounting between the second telescopic rod and the well pipe are more convenient when the well pipe is installed to the specified position.

[0018] Optionally, a clamping groove is arranged on the side wall of the connecting groove, when the movable end of the second telescopic rod enters the connecting groove, the installation groove is in communication with the connecting groove, the elastic member comprises a clamping block slidably arranged in the clamping groove, and a first spring fixedly arranged between the bottom surface of the clamping block and the bottom of the installation groove and used for driving the clamping block to enter the clamping groove.

[0019] By adopting the technical scheme, the second telescopic rod supports and fixes the well pipe through the connection of the clamping block and the clamping groove, and the installation is simple and convenient.

[0020] Optionally, the transmission member is a connecting pipe, one end of the connecting pipe is in communication with the inside of the fixed end cavity of the first electric telescopic rod, and the communication position is between the two movable ends of the first electric telescopic rod; the other end of the connecting pipe is in communication with the inside of the fixed end cavity of the second telescopic rod, and the communication position is always above the bottom surface of the movable end of the second telescopic rod; the inside of the fixed end cavity of the first electric telescopic rod, the inside of the fixed end cavity of the second telescopic rod and the inside of the connecting pipe are filled with fluid, when the movable end of the first electric telescopic rod is retracted, the fluid in the fixed end of the first electric telescopic rod is extruded and enters the fixed end of the second telescopic rod through the connecting pipe, so that the movable end of the second telescopic rod is retracted.

[0021] By adopting the above technical scheme, the fluid flows in the fixed end of the first electric telescopic rod and the fixed end of the second telescopic rod through the connecting pipe, the movable ends of the first electric telescopic rod and the second telescopic rod can be retracted and extended at the same time, so that the second telescopic rod can be controlled in linkage by controlling the first electric telescopic rod.

[0022] Optionally, a recess groove is formed on the drill bit for mounting the second telescopic rod, and a recess assembly is further included, the recess assembly is used to drive the second telescopic rod to retract into the recess groove when the hole expander is retracted.

[0023] By adopting the above technical scheme, the second telescopic rod will not interfere with the installation of the well pipe due to the arrangement of the recess assembly.

[0024] Optionally, a sliding groove is formed on the inner side wall of the recess groove, the recess assembly includes a control member arranged in the sliding groove, the control member includes a second spring arranged in the sliding groove, a baffle connected with the second spring and a control rod mounted on the baffle, one end of the control rod away from the baffle is connected with the second telescopic rod, and the second spring is in a stretched state when the movable end of the second telescopic rod is connected with the well pipe.

[0025] By adopting the above technical scheme, when the movable end of the second telescopic rod is disconnected with the well pipe, the second spring restores the deformation, so that the control rod drives the second telescopic rod to retract into the recess groove.

[0026] Optionally, the recess assembly further includes a connecting rod, one end of the connecting rod is fixed on the movable end of the first electric telescopic rod close to the second telescopic rod, the other end of the connecting rod abuts against the control rod, and a control groove is formed on the control rod, the connecting rod abuts against the side wall of the control groove close to the second telescopic rod when the movable end of the second telescopic rod is connected with the well pipe.

[0027] Through the cooperation of the connecting rod and the control groove, the movable end of the first electric telescopic rod can drive the control rod to push the second telescopic rod out of the accommodation groove when the movable end extends out of the drill bit.

[0028] To sum up, the present application has at least one of the following beneficial technical effects:

[0029] 1. Through the cooperation of the reaming assembly, the downpipe assembly and the transmission member, the drill body can adapt to the change of the diameter of the pipe well during the drilling process, and has wider applicability.

[0030] 2. The fluid flows through the connecting pipe in the fixed end of the first electric telescopic rod and the fixed end of the second telescopic rod, and the movable ends of the first electric telescopic rod and the second telescopic rod can be simultaneously retracted and extended, so that the second telescopic rod can be controlled in linkage by controlling the first electric telescopic rod.

[0031] 3. The accommodation assembly can prevent the second telescopic rod from interfering with the installation of the well pipe. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a structure schematic diagram of a downpipe drill dual-purpose reverse circulation drill of the present embodiment;

[0033] Figure 2 It is a sectional structure schematic diagram of a drill bit;

[0034] Figure 3 It is Figure 2 It is a local enlarged schematic diagram of A in the middle.

[0035] EXPLANATION OF REFERENCE NUMERALS:

[0036] 1, drill body; 2, drill rod; 3, drill bit; 31, accommodation groove; 32, sliding groove; 4, reaming assembly; 41, reaming rod; 42, hinged shaft; 43, first electric telescopic rod; 5, downpipe assembly; 51, second telescopic rod; 511, mounting groove; 52, elastic member; 521, first spring; 522, clamping block; 6, connecting pipe; 7, accommodation assembly; 71, control member; 711, second spring; 712, baffle; 713, control rod; 7131, control groove; 72, connecting rod; 8, well pipe; 81, connecting groove; 82, clamping groove. DETAILED DESCRIPTION

[0037] The following will be described in detail in combination with the accompanying Figures 1-3 The present application will be further described in detail.

[0038] Reference will be made to Figure 1 and Figure 2The embodiment of the application discloses a dual-purpose reverse circulation drilling machine of a down-the-hole drill, which comprises a drilling machine body 1, a drill rod 2 vertically arranged on one side of the drilling machine body 1 and a drill bit 3 arranged directly below the drill rod 2 and coaxially arranged with the drill rod 2, the drilling machine body 1 is used for driving the drill rod 2 to rotate around the axis of the drilling machine body 1, and further comprises a reaming assembly 4, a down-the-hole assembly 5 and a transmission part, which are all arranged on the drill bit 3.

[0039] The drill bit 3 is a cylindrical structure made of metal, the reaming assembly 4 comprises a reaming rod 41 and a hinged shaft 42, the reaming rod 41 is made of metal material, the lower end of the reaming rod 41 is movably arranged on the outer side wall of the drill bit 3, the upper end of the reaming rod 41 is provided with the hinged shaft 42, the hinged shaft 42 is fixedly arranged on the side wall of the drill bit 3, and the reaming rod 41 is rotatably arranged on the outer side wall of the drill bit 3 around the hinged shaft 42; the reaming assembly 4 further comprises a first electric telescopic rod 43 fixedly arranged in the drill bit 3, the first electric telescopic rod 43 is horizontally arranged in the drill bit 3, the end of the movable end of the first electric telescopic rod 43 is slidably connected with the reaming rod 41, and the hinged axis of the reaming rod 41 is perpendicular to the movement direction of the movable end of the first electric telescopic rod 43.

[0040] When the diameter of the drilling hole of the drilling machine body 1 changes, the movable end of the first electric telescopic rod 43 extends out of the drill bit 3, and then the end of the movable end of the first electric telescopic rod 43 is slidably connected with the reaming rod 41, the reaming rod 41 rotates around the hinged shaft 42, and the bottom end of the reaming rod 41 gradually moves away from the drill bit 3. Thus, the diameter of the drilling hole of the drill bit 3 can be increased, and the situation that the diameter of the drilling hole needs to be changed during drilling can be adapted.

[0041] The reaming rod 41 and the hinged shaft 42 are symmetrically arranged in two groups on the outer side wall of the drill bit 3, the first electric telescopic rod 43 is a bidirectional telescopic rod structure, and the ends of the two movable ends of the first electric telescopic rod 43 are slidably connected with the corresponding reaming rods 41 respectively. The arrangement of the two groups of reaming rods 41 makes the drill bit 3 more stable during drilling.

[0042] Reference Figure 2 and Figure 3The lower pipe assembly 5 comprises a second telescopic rod 51 movably arranged on the outer sidewall of the drill bit 3. The second telescopic rod 51 is vertically arranged on one side of the drill bit 3, and the movable end of the second telescopic rod 51 is vertically arranged upward. A displacement slot 31 is formed in the sidewall of the drill bit 3 for mounting the second telescopic rod 51. The second telescopic rod 51 can be completely retracted into the displacement slot 31. After being retracted into the displacement slot 31, the outer sidewall of the second telescopic rod 51 is flush with the outer sidewall of the drill bit 3. In this embodiment, the sidewall thickness of the second telescopic rod 51 near the displacement slot 31 is more than 5 times the thickness of the other sidewall. When the second telescopic rod 51 extends out of the displacement slot 31 to support the well pipe 8, one side of the second telescopic rod 51 is still located in the displacement slot 31. A mounting slot 511 is formed in the top of the movable end of the second telescopic rod 51. An elastic member 52 is arranged in the mounting slot 511. The elastic member 52 is used for clamping the well pipe 8.

[0043] The inner diameter of the well pipe 8 is greater than the diameter of the drill bit 3. A connecting groove 81 is formed in the lower end surface of the well pipe 8 for embedding the movable end of the second telescopic rod 51. The connecting groove 81 has a circular ring structure in cross section. The movable end of the second telescopic rod 51 is arranged opposite to the connecting groove 81. A clamping groove 82 is formed in the inner sidewall of the connecting groove 81. The clamping groove 82 is in communication with the connecting groove 81, and also has a circular ring structure in cross section.

[0044] When the movable end of the second telescopic rod 51 is mounted in the connecting groove 81, the clamping block 522 compresses the first spring 521, so that the clamping block 522 is retracted into the mounting slot 511. When the movable end of the second telescopic rod 51 is completely inserted into the connecting groove 81, the mounting slot 511 is in communication with the clamping groove 82. At this time, the first spring 521 restores the elastic deformation to eject the clamping block 522 from the mounting slot 511, so that the clamping block 522 is embedded in the clamping groove 82. The second telescopic rod 51 supports the well pipe 8, and the installation is simple and convenient. When the movable end of the second telescopic rod 51 needs to be extended from the connecting groove 81, the movable end of the second telescopic rod 51 moves downward. The clamping block 522 is retracted into the mounting slot 511 under the action of the conical structure, and then moves with the movable end of the second telescopic rod 51 to be separated from the well pipe 8.

[0045] The transmission member is a connecting pipe 6 arranged in the drill bit 3. The connecting pipe 6 is a rubber-made hose. One end of the connecting pipe 6 is in communication with the inside of the fixed-end cavity of the first electric telescopic rod 43, and the communication position is between the two movable ends of the first electric telescopic rod 43. The other end of the connecting pipe 6 is in communication with the inside of the fixed-end cavity of the second telescopic rod 51, and the communication position is always above the bottom surface of the movable end of the second telescopic rod 51. The fixed-end cavity of the first electric telescopic rod 43, the fixed-end cavity of the second telescopic rod 51, and the connecting pipe 6 are filled with a fluid, which can be air, water or other liquid. When the movable end of the first electric telescopic rod 43 is retracted, the fluid in the fixed end of the first electric telescopic rod 43 is extruded and enters the fixed end of the second telescopic rod 51 through the connecting pipe 6, so that the movable end of the second telescopic rod 51 is retracted, so that the movable ends of the first electric telescopic rod 43 and the second telescopic rod 51 can be retracted or extended at the same time.

[0046] In use, the movable end of the first electric telescopic rod 43 is controlled to extend out of the drill bit 3 and abut against the reaming rod 41, thereby driving the reaming rod 41 to rotate around the hinge shaft 42, expanding the drilling diameter of the drill bit 3. At this time, the fluid flows from the fixed end of the second telescopic rod 51 to the fixed end of the first electric telescopic rod 43, so that the movable end of the second telescopic rod 51 extends into the connecting groove 81 and is connected to the well pipe 8, so that the second telescopic rod 51 supports the well pipe 8.

[0047] The drill bit 3 is also provided with a giving component 7. The drill bit 3 is provided with a giving slot 31 for installing the second telescopic rod 51. The side wall of the giving slot 31 is provided with a sliding groove 32. The giving component 7 includes a control member 71 and a connecting rod 72. The control member 71 includes a second spring 711 arranged in the sliding groove 32, a baffle 712 connected to the second spring 711, and a control rod 713 mounted on the baffle 712. One end of the control rod 713 away from the baffle 712 is connected to the outer side wall of the second telescopic rod 51. When the movable end of the second telescopic rod 51 is connected to the well pipe 8, the second spring 711 is in a stretched state. In this embodiment, two second springs 711 are provided, which can make the force on the second telescopic rod 51 more stable.

[0048] When the well pipe 8 is installed, the movable end of the first electric telescopic rod 43 is controlled to retract, the reaming rod 41 rotates around the hinge shaft 42 to be in close contact with the side wall of the drill bit 3 without the action force of the movable end of the first electric telescopic rod 43, at this time, the fluid flows from the fixed end of the first electric telescopic rod 43 into the fixed end of the second telescopic rod 51, the movable end of the second telescopic rod 51 retracts into the fixed end of the second telescopic rod 51 under the extrusion of the fluid, so that the movable end of the second telescopic rod 51 is out of the connecting groove 81 of the well pipe 8, and the movable end of the second telescopic rod 51 moves downward in the process of being out of the connecting groove 81, the clamping block 522 is out of the clamping groove 82 and retracts into the installation groove 511 under the action of the necked structure, and then the second telescopic rod 51 is out of the connecting groove 81 of the well pipe 8, and the well pipe 8 is installed on the inner wall of the well.

[0049] The bottom end of the connecting rod 72 is fixed on the movable end of the first electric telescopic rod 43 close to the second telescopic rod 51, and the top end of the connecting rod 72 abuts against the lower end of the control rod 713, the control groove 7131 is arranged on the control rod 713, the arrangement direction of the control groove 7131 is the same as the length direction of the control rod 713, and the length of the control groove 7131 is the transverse distance of the second telescopic rod 51 extending out of the drill bit 3.

[0050] When the movable end of the first electric telescopic rod 43 extends out of the drill bit 3, the connecting rod 72 moves with the extension of the movable end of the first electric telescopic rod 43, and the connecting rod 72 abuts against the side wall of the control groove 7131 close to the second telescopic rod 51, so that the connecting rod 72 drives the control rod 713 to push the second telescopic rod 51 out of the accommodation groove 31; at the same time, the movable end of the first electric telescopic rod 43 extends out of the drill bit 3 to exert an action force on the reaming rod 41, the reaming rod 41 rotates around the hinge shaft 42, the fluid in the fixed end of the second telescopic rod 51 enters the fixed end of the first electric telescopic rod 43 through the connecting pipe 6, and the movable end of the second telescopic rod 51 extends and is embedded in the connecting groove 81, so that the movable end of the second telescopic rod 51 is connected with the well pipe 8. Through the cooperation of the connecting rod 72 and the control groove 7131, the movable end of the first electric telescopic rod 43 can drive the control rod 713 to push the second telescopic rod 51 out of the accommodation groove 31 when the movable end of the first electric telescopic rod 43 extends out of the drill bit 3, so that the second telescopic rod 51 is connected with the well pipe 8, which is simple and convenient to operate.

[0051] The implementation principle of the dual-purpose reverse circulation drilling machine of the down-the-hole drilling machine is as follows: when the drilling machine body 1 needs to adapt to the change of the drilling diameter during drilling, the first electric telescopic rod 43 is started, the movable end of the first electric telescopic rod 43 abuts against the reaming rod 41 and makes the reaming rod 41 rotate around the hinge shaft 42, and the drilling diameter of the drill bit 3 is increased; at the same time, fluid flows from the inside of the fixed end of the second telescopic rod 51 to the inside of the fixed end of the first electric telescopic rod 43, so that the movable end of the second telescopic rod 51 extends into the connecting groove 81 of the well pipe 8 and is connected with the well pipe 8; after the well pipe 8 is installed, the movable end of the first electric telescopic rod 43 is controlled to be retracted, so that the reaming rod 41 rotates and is attached to the side wall of the drill bit 3; at this time, fluid flows from the inside of the fixed end of the first electric telescopic rod 43 to the inside of the fixed end of the second telescopic rod 51, so that the movable end of the second telescopic rod 51 is retracted into the fixed end of the second telescopic rod 51, so that the movable end of the second telescopic rod 51 is separated from the well pipe 8, and the second telescopic rod 51 is retracted into the accommodation groove 31 under the action of the second spring 711, and the well pipe 8 is installed on the inner wall of the well.

[0052] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application, so that: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A dual-purpose reverse circulation drilling rig for both casing drilling and drilling, characterized in that, The drilling rig includes a drilling rig body (1), a drill rod (2) disposed on one side of the drilling rig body (1), and a drill bit (3) disposed on the drill rod (2), and further includes: A reaming assembly (4) is used to change the drilling diameter of the drill bit (3); The downpipe assembly (5) is used to support the well pipe (8) installed in the well; A transmission component, the transmission component being used to drive the downtube assembly (5) to disengage from the well casing (8) after drilling is completed; The reaming assembly (4) includes a reaming rod (41) disposed on the side wall of the drill bit (3) and a hinge shaft (42) for mounting the reaming rod (41). The reaming rod (41) is rotatably connected to the outer side wall of the drill bit (3) through the hinge shaft (42). The reaming assembly (4) also includes a first electric telescopic rod (43) disposed inside the drill bit (3). The end of the movable end of the first electric telescopic rod (43) is slidably connected to the reaming rod (41). The reaming rod (41) and the hinge shaft (42) are symmetrically arranged in two sets on the outer side wall of the drill bit (3). The first electric telescopic rod (43) is a bidirectional telescopic rod structure. The ends of the two movable ends of the first electric telescopic rod (43) are slidably connected to the corresponding reaming rod (41). A connecting groove (81) is provided on the side wall of the well pipe (8), and a snap-fit ​​groove (82) is provided on the side wall of the connecting groove (81). The lower pipe assembly (5) includes a second telescopic rod (51) vertically arranged on one side of the drill bit (3). The movable end of the second telescopic rod (51) is directly opposite to the connecting groove (81). An installation groove (511) is provided on the movable end of the second telescopic rod (51), and an elastic element (52) for snap-fitting with the well pipe (8) is provided in the installation groove (511). The connecting groove (81) has a snap-fit ​​groove (82) on its side wall. When the movable end of the second telescopic rod (51) enters the connecting groove (81), the mounting groove (511) communicates with the connecting groove (81). The elastic element (52) includes a snap-fit ​​block (522) with one end slidably disposed in the snap-fit ​​groove (82), and a first spring (521) fixedly disposed between the bottom surface of the snap-fit ​​block (522) and the bottom of the mounting groove (511) and used to drive the snap-fit ​​block (522) into the snap-fit ​​groove (82). The transmission component is a connecting pipe (6). One end of the connecting pipe (6) is connected to the cavity of the fixed end of the first electric telescopic rod (43), and the connection position is located between the two movable ends of the first electric telescopic rod (43). The other end of the connecting pipe (6) is connected to the cavity of the fixed end of the second telescopic rod (51), and the connection position is always located above the bottom surface of the movable end of the second telescopic rod (51). The cavity of the fixed end of the first electric telescopic rod (43), the cavity of the fixed end of the second telescopic rod (51), and the connecting pipe (6) are filled with fluid. When the movable end of the first electric telescopic rod (43) contracts, the fluid in the fixed end of the first electric telescopic rod (43) is squeezed and enters the fixed end of the second telescopic rod (51) through the connecting pipe (6), causing the movable end of the second telescopic rod (51) to contract.

2. The dual-purpose reverse circulation drilling rig for casing drilling as described in claim 1, characterized in that: The drill bit (3) is provided with a relief groove (31) for the installation of the second telescopic rod (51), and also includes a relief component (7), which is used to drive the second telescopic rod (51) into the relief groove (31) when the reaming rod (41) retracts.

3. A dual-purpose reverse circulation drilling rig for both casing drilling and drilling as described in claim 2, characterized in that: The inner wall of the clearance groove (31) is provided with a sliding groove (32). The clearance component (7) includes a control component (71) disposed in the sliding groove (32). The control component (71) includes a second spring (711) disposed in the sliding groove (32), a baffle (712) connected to the second spring (711), and a control rod (713) installed on the baffle (712). The end of the control rod (713) away from the baffle (712) is connected to the second telescopic rod (51). When the movable end of the second telescopic rod (51) is connected to the well pipe (8), the second spring (711) is in a stretched state.

4. A dual-purpose reverse circulation drilling rig for both casing drilling and drilling as described in claim 3, characterized in that: The clearance assembly (7) also includes a connecting rod (72), one end of which is fixed to the movable end of the first electric telescopic rod (43) near the second telescopic rod (51), and the other end of which abuts against the control rod (713). The control rod (713) has a control groove (7131). When the movable end of the second telescopic rod (51) is connected to the well pipe (8), the connecting rod (72) abuts against the side wall of the control groove (7131) near the second telescopic rod (51).

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