A propulsion device for an eight-legged drilling rig

Abstract

This invention relates to the field of drilling equipment technology, specifically to a propulsion device for an eight-legged drilling rig, comprising an outer arm assembly, a hydraulic cylinder mounting arm assembly, and an inner arm assembly. The outer arm assembly includes an outer arm cylinder with a drill rod fixing seat on its lower side for connection to a drilling rig drive assembly. The hydraulic cylinder mounting arm assembly includes a mounting arm cylinder sleeved inside the outer arm cylinder and reciprocating relative to the axis of the outer arm cylinder. The inner arm assembly includes an inner arm cylinder sleeved inside the mounting arm cylinder and reciprocating relative to the axis of the mounting arm cylinder. An inner arm connecting assembly for connecting an impactor connector is fixedly connected to the right end of the inner arm cylinder. A hydraulic drive device is disposed within the inner arm cylinder, which enables the inner arm cylinder to extend and retract within the mounting arm cylinder and the mounting arm cylinder to extend and retract within the outer arm cylinder. This device helps improve the stability of the telescopic arm and achieves three-stage extension and retraction to meet drilling requirements.

Description

Technical Field

[0001] This invention relates to the field of drilling equipment technology, and more specifically to a propulsion device for an eight-legged drilling rig. Background Technology

[0002] In modern engineering operations, hydraulic telescopic booms serve as key components of equipment such as drilling rigs, and their performance directly determines the overall working range, operational efficiency, and stability of the machine. Currently, the most common telescopic booms on the market are rectangular and circular cross-sections. Among them, circular cross-section telescopic booms are increasingly widely used due to their advantages such as high torsional strength, uniform stress distribution, and aesthetically pleasing appearance.

[0003] Existing circular hydraulic telescopic booms typically use a single hydraulic cylinder in conjunction with a wire rope or chain telescopic mechanism to achieve multi-stage extension and retraction. However, under long-term high-load operation, the wire rope or chain is prone to stretching, wear, and even breakage, leading to asynchronous extension and retraction of each boom section. This not only affects operational accuracy but also poses serious safety hazards. Furthermore, replacing and maintaining the wire rope or chain is cumbersome, increasing equipment maintenance costs and downtime. Summary of the Invention

[0004] The purpose of this invention is to provide a propulsion device for an eight-legged drilling rig. This device helps to improve the stability of the telescopic boom and achieves three-stage telescopic extension of the outer boom cylinder, mounting boom cylinder, and inner boom cylinder by setting a hydraulic drive device to meet the drilling requirements.

[0005] The technical solution of the present invention is as follows: a propulsion device for an eight-legged drilling rig, comprising an outer arm assembly, a hydraulic cylinder mounting arm assembly, and an inner arm assembly. The outer arm assembly includes an outer arm cylinder, the lower side of which is provided with a drill rod fixing seat for connection with a drilling rig drive assembly. The hydraulic cylinder mounting arm assembly includes a mounting arm cylinder sleeved inside the outer arm cylinder and reciprocating relative to the axis of the outer arm cylinder. The inner arm assembly includes an inner arm cylinder sleeved inside the mounting arm cylinder and reciprocating relative to the axis of the mounting arm cylinder. An inner arm connecting assembly for connecting an impactor connector is fixedly connected to the right end of the inner arm cylinder. A hydraulic drive device is provided inside the inner arm cylinder, the hydraulic drive device being used to realize the extension and retraction of the inner arm cylinder within the mounting arm cylinder and the extension and retraction of the mounting arm cylinder within the outer arm cylinder.

[0006] Furthermore, the hydraulic drive device includes a first cylinder body, a second cylinder body, and a cylinder rod body, which are sequentially sleeved from the outside to the inside. The second cylinder body has a second cylinder body seal and a second cylinder body piston correspondingly arranged at its left and right ends. The first cylinder body is internally connected to the second cylinder body seal, and the right side of the second cylinder body seal is connected to the left side of the inner arm cylinder body. The second cylinder body seal can drive the first cylinder body to reciprocate along the axis of the second cylinder body. The left end of the cylinder rod body is provided with a cylinder rod body connecting ring, a first inlet / outlet port, and a second inlet / outlet port. An integral cylinder rod body connecting piece and a second cylinder body end cap are sleeved on the cylinder rod body. The right end of the cylinder rod body is provided with a cylinder rod body piston. The left end of the second cylinder body is sleeved outside the second cylinder body end cap and forms a seal with the cylinder rod body connecting piece. The first inlet / outlet port and the second inlet / outlet port are respectively connected to the second cylinder body and the first cylinder body.

[0007] Furthermore, the left and right ends of the outer boom cylinder are respectively provided with the first set of welded parts and the first dustproof component of the outer boom, and the cylinder rod connecting ring is connected to the first set of welded parts of the outer boom; the left and right ends of the mounting boom cylinder are respectively provided with the first connecting component and the second dustproof component, and the cylinder rod connecting piece is connected to the first connecting component and can slide back and forth along the cylinder rod axis.

[0008] Furthermore, the first set of welded components of the outer arm includes an outer arm pin fixing block, which is fixedly connected to the outer arm end cap. The outer arm cylinder is detachably connected to the outer arm pin fixing block. After the outer arm cylinder is connected to the outer arm pin fixing block, a pin hole perpendicular to its axis is formed. The pin hole is used to connect a pin, and the pin is connected to the cylinder rod connecting ring.

[0009] Furthermore, the inner wall of the right end of the outer arm cylinder is provided with three first keyways spaced apart along the circumferential direction, and the outer wall of the mounting arm cylinder is provided with three sets of first protruding keys evenly distributed along the circumferential direction. The first protruding keys are arranged along the axial direction of the mounting arm cylinder and match the first keyways. The inner wall of the right end of the mounting arm cylinder is provided with three second keyways spaced apart along the circumferential direction, and the outer wall of the inner arm cylinder is provided with three sets of second protruding keys evenly distributed along the circumferential direction. The second protruding keys are arranged along the axial direction of the inner arm cylinder and match the second keyways.

[0010] Furthermore, the first dustproof component includes a second set of welded parts for the outer arm, several dustproof pads for the outer arm, and a fixing ring. The second set of welded parts for the outer arm is fixedly connected to the right end of the outer arm cylinder. Several dustproof pads for the outer arm are placed between the second set of welded parts for the outer arm and the fixing ring. The second set of welded parts for the outer arm is fixedly connected to the fixing ring. The fixing ring is provided with third keyways at intervals to match the three sets of first protruding keys evenly distributed along the circumferential direction on the outer wall of the mounting arm cylinder.

[0011] Furthermore, both the outer arm dustproof pad and the fixing ring are formed by joining two half-piece components; and the joints between the layers of the outer arm dustproof pad and between the joints of the outer arm dustproof pad and the fixing ring are staggered in the circumferential direction; the internal connection relationship of the second dustproof component is the same as that of the first dustproof component, and the size of the corresponding component of the second dustproof component is smaller than the size of the corresponding component of the first dustproof component.

[0012] Furthermore, the inner arm connecting assembly includes an inner arm sealing plate fixed to the right end of the inner arm cylinder. The inner arm sealing plate is fixedly connected to a rectangular frame. The rectangular frame has a first through hole penetrating the front and rear sides. The impactor connector extends into the rectangular frame and is fixed by a drill bit connecting pin passing through the first through hole. The drill bit connecting pin has a second through hole on its front side. The second through hole is connected to a limiting device to prevent it from sliding out of the first through hole.

[0013] Furthermore, the limiting device includes a nut assembly, wherein the drill bit connecting pin passes through the second through hole by a bolt and is fixed by the nut assembly.

[0014] Furthermore, the limiting device includes a fixing plate fixed to the front side of the rectangular frame, a pin passing through the fixing plate, the pin passing through a second through hole, and a third through hole for connecting an R-type plug at the right end of the pin.

[0015] Compared with the prior art, the present invention has the following advantages: 1. This device utilizes a hydraulic drive system to achieve three-stage extension and retraction of the outer boom, mounting boom, and inner boom to meet drilling requirements, thus reducing safety hazards. Simultaneously, it eliminates the cumbersome work of replacing and maintaining wire ropes or chains, reducing equipment maintenance costs and downtime.

[0016] 2. This device, through the cooperation of the limiting components and the protruding key, prevents the outer boom cylinder, the mounting boom cylinder, and the inner boom cylinder from rotating during extension and retraction, thereby improving the stability of the telescopic boom.

[0017] 3. The device has a simple and compact structure, which improves the ease of installation and disassembly. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is an exploded view of the outer arm assembly, the hydraulic cylinder mounting arm assembly, and the inner arm assembly of the present invention. Figure 3 This is an exploded view of the inner arm assembly of the present invention; Figure 4 For the present invention Figure 1 Enlarged view of part A in the middle; Figure 5 For the present invention Figure 1 Enlarged view of part B in the middle section; Figure 6 For the present invention Figure 3 Enlarged view of part C in the middle; Figure 7 This is a schematic diagram of the impactor connector structure of the present invention; Figure 8 This is a schematic diagram of the structure of the first limiting member and the second limiting member of the present invention; Figure 9 This is a schematic diagram of the limiting device structure according to the second embodiment of the present invention; In the diagram: 100-Outer boom assembly, 110-Outer boom cylinder, 1101-First limiting component, 120-Drill rod fixing seat, 130-Outer boom first welded assembly, 1301-Outer boom pin fixing block, 1302-Outer boom end cap, 1303-Pin, 140-Outer boom second welded assembly, 1401-Outer boom dustproof pad, 1402-Fixing ring, 200-Cylinder mounting arm assembly, 210-Mounting arm cylinder, 2101-Second limiting component, 220-First protruding key, 230-First connecting assembly, 240-Second dustproof assembly, 300-Inner boom assembly, 310-Inner boom cylinder, 320-Second protruding key, 330-Cylinder first cylinder, 34 0-Second cylinder body, 3401-Second cylinder body seal, 3402-Second cylinder body piston, 350-Cylinder rod, 3501-Cylinder rod connecting ring, 3502-Cylinder rod piston, 3503-Second cylinder body end cap, 3504-Cylinder rod connecting piece, 3505-First oil inlet / outlet, 3506-Second oil inlet / outlet, 400-Inner arm connecting assembly, 410-Inner arm sealing plate, 420-Rectangular frame, 4201-First through hole, 4202-Second through hole, 4203-Nut assembly, 430-Drill bit connecting pin, 500-Fixing plate, 510-Pin, 520-Third through hole, 600-Impacter connector. Detailed Implementation

[0019] To make the above features and advantages of the present invention more readily understood, specific embodiments are described below in conjunction with the accompanying drawings, but the present invention is not limited thereto. Example 1

[0020] like Figure 1As shown, a propulsion device for an eight-legged drilling rig includes an outer arm assembly 100, a hydraulic cylinder mounting arm assembly 200, and an inner arm assembly 300. The outer arm assembly 100 includes an outer arm cylinder 110, and the lower side of the outer arm cylinder 110 is provided with a drill rod fixing seat 120 for connecting with the drilling rig drive assembly. The drill rod fixing seat 120 is fixed to the drilling rig drive assembly so that it will not slide. The hydraulic cylinder mounting arm assembly 200 includes a mounting arm cylinder 210 sleeved inside the outer arm cylinder 110, which can reciprocate relative to the axis of the outer arm cylinder 110. The inner arm assembly 300 includes an inner arm cylinder 310 sleeved inside the mounting arm cylinder 210, which can reciprocate relative to the axis of the mounting arm cylinder 210. The right end of the inner arm cylinder 310 is fixedly connected to an inner arm connecting assembly 400 for connecting an impactor connector 600. A hydraulic drive device is provided inside the inner arm cylinder 310, which is used to realize the extension and retraction of the inner arm cylinder 310 within the mounting arm cylinder 210 and within the outer arm cylinder 110. The hydraulic drive device drives the inner arm cylinder 310 and the mounting arm cylinder 210 to extend and retract sequentially, and then drilling is performed through the impactor connector 600 installed on the inner arm connecting assembly 400.

[0021] In this embodiment, as Figure 2 , 3 As shown in Figure 6, the hydraulic drive device includes a first cylinder body 330, a second cylinder body 340, and a cylinder rod body 350, which are sequentially arranged from the outside to the inside. A second cylinder seal 3401 and a second cylinder piston 3402 are correspondingly provided at the left and right ends of the second cylinder body 340. The first cylinder body 330 is internally connected to the second cylinder seal 3401, and the right side of the second cylinder seal 3401 is connected to the left side of the inner arm cylinder body 310. The second cylinder seal 3401 can drive the first cylinder body 330 to reciprocate along the axial direction of the second cylinder body 340. The left end of the cylinder rod 350 is provided with a cylinder rod connecting ring 3501, a first oil inlet / outlet 3505, and a second oil inlet / outlet 3506, arranged sequentially from left to right. A cylinder rod connecting piece 3504 and a second cylinder end cap 3503, which are integrally connected, are fitted onto the cylinder rod 350. A cylinder rod piston 3502 is provided at the right end of the cylinder rod 350. The left port of the second cylinder 340 is fitted outside the second cylinder end cap 3503 and forms a seal with the cylinder rod connecting piece 3504. The first oil inlet / outlet 3505 and the second oil inlet / outlet 3506 are respectively connected to the second cylinder 340 and the first cylinder 330.

[0022] The outer boom cylinder 110 has a first set of welded parts 130 and a first dustproof component at its left and right ends, respectively. The cylinder rod connecting ring 3501 is connected and fixed to the first set of welded parts 130. The mounting boom cylinder 210 has a first connecting component 230 and a second dustproof component 240 at its left and right ends, respectively. The cylinder rod connecting part 3504 is connected to the first connecting component 230 and can reciprocate along the axis of the cylinder rod 350.

[0023] Specifically, the first welded component 130 of the outer arm includes an outer arm pin fixing block 1301, which is fixedly connected to the outer arm end cap 1302. The left side end of the outer arm cylinder 110 is detachably connected to the outer arm pin fixing block 1301 by bolts and nuts. After the outer arm cylinder 110 is connected to the outer arm pin fixing block 1301, a pin hole perpendicular to its axis is formed. The pin hole is used to connect the pin 1303. The cylinder rod connecting ring 3501 is connected to the pin 1303.

[0024] The cylinder rod 350 is fixed in place by the action of the pin 1303 and the cylinder rod connecting ring 3501, and the second cylinder 340 is connected to the first cylinder 330. When the telescopic arm extends, the first oil inlet / outlet 3505 feeds oil into the second cylinder 340, and the second oil inlet / outlet 3506 discharges oil into the first cylinder 330. This causes the second cylinder seal 3401 to drive the first cylinder 330 to slide along the axis of the second cylinder 340. Furthermore, because the right side of the second cylinder seal 3401 is connected to the left side of the inner arm cylinder 310, the inner arm cylinder 310 can slide out until the second cylinder seal 3401 reaches the second cylinder piston 3402. When the second cylinder seal 3401 reaches the second cylinder piston 3402, the cylinder rod connector 3504 drives the second cylinder end cap 3503 to slide. The second cylinder end cap 3503 drives the second cylinder 340 to slide along the axis of the cylinder rod 350. Since the cylinder rod connector 3504 is connected to the first connecting assembly 230 of the mounting arm cylinder 210, the mounting arm cylinder 210 extends until the second cylinder end cap 3503 reaches the cylinder rod piston 3502. When retracting, the first oil inlet / outlet 3505 draws oil into the second cylinder 340, and the second oil inlet / outlet 3506 feeds oil into the first cylinder 330. The rest of the principle is the same.

[0025] In this embodiment, as Figure 1 , 2As shown in Figures 4 and 8, the inner wall of the right end of the outer arm cylinder 110 is provided with three first keyways spaced along the circumferential direction. Specifically, the outer arm cylinder 110 has three first rectangular mounting holes spaced along the circumferential direction near the right end. Each first rectangular mounting hole has a first limiting member 1101 with a radial cross-section in the shape of an "I". The upper and lower surfaces of the middle part of the first limiting member 1101 are flush with the outer and inner walls of the outer arm cylinder 110. The front and rear ends of the first limiting member 1101 are provided with protrusions to form a first keyway on the inner wall of the outer arm cylinder 110. The outer wall of the mounting arm cylinder 210 is provided with three sets of first protruding keys 220 evenly distributed along the circumferential direction. The first protruding keys 220 are arranged along the axial direction of the mounting arm cylinder 210 and match the first keyways.

[0026] The inner wall of the right end of the mounting arm cylinder 210 is provided with three second keyways spaced along the circumferential direction. Specifically, the outer arm cylinder 110 has three second rectangular mounting holes spaced along the circumferential direction near the right end. Each second rectangular mounting hole has a second limiting member 2101 with a radial cross-section in the shape of an "I". The upper and lower surfaces of the middle part of the second limiting member 2101 are flush with the outer and inner walls of the mounting arm cylinder 210. The front and rear ends of the second limiting member 2101 are provided with protrusions to form a second keyway on the inner wall of the mounting arm cylinder 210. The outer wall of the inner arm cylinder 310 has three sets of second protruding keys 320 evenly distributed along the circumferential direction. The second protruding keys 320 are arranged along the axial direction of the inner arm cylinder 310 and match the second keyways.

[0027] The first dustproof component includes a second set of welded parts 140 of the outer arm, several outer arm dustproof pads 1401, and a fixing ring 1402. The second set of welded parts 140 of the outer arm is fixedly connected to the right end of the outer arm cylinder 110. Several outer arm dustproof pads 1401 are placed between the second set of welded parts 140 and the fixing ring 1402. The second set of welded parts 140 and the fixing ring 1402 are fixedly connected by bolts. The fixing ring 1402 is also provided with three third keyways at intervals. The third keyways are used to match the three sets of first protruding keys 220 on the outer wall of the mounting arm cylinder 210.

[0028] In this embodiment, as Figure 4 As shown, the outer arm dustproof pad 1401 and the fixing ring 1402 are both formed by joining two half-piece components; and the joints between the layers of the outer arm dustproof pad 1401 and the joint between the outer arm dustproof pad 1401 and the fixing ring 1402 are all staggered in the circumferential direction.

[0029] The internal connection relationship of the second dustproof component 240 is the same as that of the first dustproof component, and the size of the corresponding part of the second dustproof component 240 is smaller than the size of the corresponding part of the first dustproof component.

[0030] Both the outer arm dustproof pad 1401 and the fixing ring 1402 are made of two half-piece parts joined together and tightened with bolts. This is to facilitate better assembly or maintenance and replacement. The misalignment of the joints is to improve dustproof performance.

[0031] In this embodiment, as Figure 5 , 7 As shown, the inner arm connecting assembly 400 includes an inner arm sealing plate 410 fixed to the right end of the inner arm cylinder 310. The inner arm sealing plate 410 is fixedly connected to a rectangular frame 420. The rectangular frame 420 is provided with a first through hole 4201 penetrating the front and rear sides. The impactor connector 600 extends into the rectangular frame 420 and is fixed by a drill bit connecting pin 430 passing through the first through hole 4201. The front end of the drill bit connecting pin 430 is provided with a second through hole 4202. The second through hole 4202 is connected to a limiting device to prevent the drill bit connecting pin 430 from sliding out of the first through hole 4201.

[0032] Specifically, the limiting device includes a nut assembly 4203, and the drill bit connecting pin 430 passes through the second through hole 4202 by bolts and is fixed by the nut assembly 4203.

[0033] After the impactor connector 600 is placed into the rectangular frame 420, the drill bit connecting pin 430 passes through the first through hole 4201, and then the bolt passes through the second through hole 4202. After tightening the nut assembly 4203, the impactor connector 600 can be fixed for drilling operations. Example 2

[0034] like Figure 9 As shown, the difference between this embodiment and Embodiment 1 lies in the limiting device; otherwise, they are the same as in Embodiment 1. Specifically, the limiting device includes a fixing plate 500 fixed to the front side of the rectangular frame 420. A pin 510 is provided on the fixing plate 500. The pin 510 can pass through the second through hole 4202, and the right end of the pin 510 is provided with a third through hole 530 for connecting an R-type plug.

[0035] After the impactor connector 600 is placed into the rectangular frame 420, the pin 510 passes through the second through hole 4202, and then the R-type plug is inserted into the third through hole 530 to lock the drill bit connecting pin 430. This method can avoid the inconvenience of installing and disassembling the bolt and nut assembly 4203.

[0036] The above description is only a preferred embodiment of the present invention. For those skilled in the art, designing different forms of propulsion devices for eight-legged drilling rigs does not require creative labor based on the teachings of the present invention. All equivalent changes, modifications, substitutions and variations made in accordance with the scope of the patent application of the present invention without departing from the principles and spirit of the present invention shall be covered by the present invention.

Claims

1. A propulsion device for an eight-legged drilling rig, comprising an outer arm assembly (100), a hydraulic cylinder mounting arm assembly (200), and an inner arm assembly (300), characterized in that, The outer boom assembly (100) includes an outer boom cylinder (110), the lower side of which is provided with a drill rod fixing seat (120) for connection with the drilling rig drive assembly; the hydraulic cylinder mounting arm assembly (200) includes a mounting arm cylinder (210) sleeved inside the outer boom cylinder (110) and reciprocating relative to the axis of the outer boom cylinder (110); the inner boom assembly (300) includes a mounting arm cylinder (210) sleeved inside the mounting arm cylinder (210) and reciprocating relative to the axis of the outer boom cylinder (110). An inner arm cylinder (310) is installed and slides back and forth along the axial direction of the arm cylinder (210); an inner arm connecting assembly (400) for connecting an impactor connector (600) is fixedly connected to the right end of the inner arm cylinder (310); a hydraulic drive device is provided inside the inner arm cylinder (310); the hydraulic drive device is used to realize the extension and retraction of the inner arm cylinder (310) inside the arm cylinder (210) and the extension and retraction of the arm cylinder (210) inside the outer arm cylinder (110).

2. The propulsion device for an eight-legged drilling rig according to claim 1, characterized in that, The hydraulic drive device includes a first cylinder body (330), a second cylinder body (340), and a cylinder rod (350) sequentially arranged from the outside to the inside; the second cylinder body (340) has a second cylinder seal (3401) and a second cylinder piston (3402) respectively arranged on the left and right ends. The first cylinder body (330) is internally connected to the second cylinder seal (3401), and the right side of the second cylinder seal (3401) is connected to the left side of the inner arm cylinder body (310). The second cylinder seal (3401) can drive the first cylinder body (330) to reciprocate along the axis of the second cylinder body (340); the cylinder rod (350) The left end of the cylinder is provided with a cylinder rod connecting ring (3501), a first oil inlet / outlet (3505), and a second oil inlet / outlet (3506). The cylinder rod (350) is fitted with an integral cylinder rod connector (3504) and a second cylinder end cap (3503). The right end of the cylinder rod (350) is provided with a cylinder rod piston (3502). The left port of the second cylinder (340) is fitted outside the second cylinder end cap (3503) and forms a seal with the cylinder rod connector (3504). The first oil inlet / outlet (3505) and the second oil inlet / outlet (3506) are respectively connected to the second cylinder (340) and the first cylinder (330).

3. The propulsion device for an eight-legged drilling rig according to claim 2, characterized in that, The left and right ends of the outer boom cylinder (110) are respectively provided with the first set of welded parts (130) and the first dustproof component. The cylinder rod connecting ring (3501) is connected to the first set of welded parts (130) of the outer boom. The left and right ends of the mounting boom cylinder (210) are respectively provided with the first connecting component (230) and the second dustproof component (240). The cylinder rod connecting part (3504) is connected to the first connecting component (230) and can slide back and forth along the axis of the cylinder rod (350).

4. The propulsion device for an eight-legged drilling rig according to claim 3, characterized in that, The first welded component (130) of the outer arm includes an outer arm pin fixing block (1301), which is fixedly connected to the outer arm end cap (1302). The outer arm cylinder (110) is detachably connected to the outer arm pin fixing block (1301). After the outer arm cylinder (110) is connected to the outer arm pin fixing block (1301), a pin hole perpendicular to its axis is formed. The pin hole is used to connect a pin (1303), which is connected to the cylinder rod connecting ring (3501).

5. A propulsion device for an eight-legged drilling rig according to claim 1, 2, 3 or 4, characterized in that, The inner wall of the right end of the outer arm cylinder (110) is provided with three first keyways at intervals along the circumferential direction. The outer wall of the mounting arm cylinder (210) is provided with three sets of first protruding keys (220) evenly distributed along the circumferential direction. The first protruding keys (220) are arranged along the axial direction of the mounting arm cylinder (210) and match the first keyways. The inner wall of the right end of the mounting arm cylinder (210) is provided with three second keyways at intervals along the circumferential direction. The outer wall of the inner arm cylinder (310) is provided with three sets of second protruding keys (320) evenly distributed along the circumferential direction. The second protruding keys (320) are arranged along the axial direction of the inner arm cylinder (310) and match the second keyways.

6. A propulsion device for an eight-legged drilling rig according to claim 3 or 4, characterized in that, The first dustproof component includes a second set of welded parts (140) of the outer arm, a plurality of dustproof pads (1401) of the outer arm, and a fixing ring (1402). The second set of welded parts (140) of the outer arm is fixedly connected to the right end of the outer arm cylinder (110). The plurality of dustproof pads (1401) of the outer arm are placed between the second set of welded parts (140) of the outer arm and the fixing ring (1402). The second set of welded parts (140) of the outer arm and the fixing ring (1402) are fixedly connected. The fixing ring (1402) is provided with a third keyway at intervals for matching the three sets of first protruding keys (220) evenly distributed along the circumferential direction on the outer wall of the mounting arm cylinder (210).

7. A propulsion device for an eight-legged drilling rig according to claim 6, characterized in that, The outer arm dustproof pad (1401) and the fixing ring (1402) are both formed by joining two half-piece components; and the joints between the layers of the outer arm dustproof pad (1401) and the joints between the outer arm dustproof pad (1401) and the fixing ring (1402) are all staggered in the circumferential direction; the internal connection relationship of the second dustproof component (240) is the same as that of the first dustproof component, and the size of the corresponding component of the second dustproof component (240) is smaller than that of the corresponding component of the first dustproof component.

8. A propulsion device for an eight-legged drilling rig according to claim 1, 2, 3, 4 or 7, characterized in that, The inner arm connecting assembly (400) includes an inner arm sealing plate (410) fixed to the right end of the inner arm cylinder (310). The inner arm sealing plate (410) is fixedly connected to a rectangular frame (420). The rectangular frame (420) is provided with a first through hole (4201) penetrating the front and rear sides. The impactor connector (600) extends into the rectangular frame (420) and is fixed by a drill bit connecting pin (430) passing through the first through hole (4201). The drill bit connecting pin (430) is provided with a second through hole (4202) on its front side. The second through hole (4202) is connected to a limiting device to prevent it from sliding out of the first through hole (4201).

9. A propulsion device for an eight-legged drilling rig according to claim 8, characterized in that, The limiting device includes a nut assembly (4203), and the drill bit connecting pin (430) passes through the second through hole (4202) by bolts and is fixed by the nut assembly (4203).

10. A propulsion device for an eight-legged drilling rig according to claim 8, characterized in that, The limiting device includes a fixing plate (500) fixed to the front side of the rectangular frame (420), a pin (510) is provided on the fixing plate (500), the pin (510) can pass through the second through hole (4202), and the right end of the pin (510) is provided with a third through hole (530) for connecting the R-type plug.

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