Double-layer grouting drill pipe

Abstract

The application discloses a double-layer grouting drill pipe, which comprises an outer pipe and an inner pipe coaxially arranged in the outer pipe, the inner pipe is threadedly connected with the outer pipe, a through hole in the middle of the inner pipe is an inner channel, a gap between the inner wall of the outer pipe and the outer wall of the inner pipe is an outer channel, a tail section of the outer pipe is provided with a connecting inner thread and a concentric positioning sleeve, and a front section of the outer pipe is provided with a connecting outer thread matched with the connecting inner thread and a concentric positioning shaft matched with the concentric positioning sleeve, so that when a plurality of double-layer grouting drill pipes are connected, the connection is realized through the connecting inner thread and the connecting outer thread, and the concentricity is realized through the concentric positioning sleeve and the concentric positioning shaft.

Description

Technical Field

[0001] This invention relates to the field of drilling equipment technology, and in particular to a grouting drill rod. Background Technology

[0002] Existing small-diameter drill rods are made from a single outer tube, making dual-slurry grouting impossible. To achieve dual-slurry grouting, the drill rod must be assembled from an inner and outer tube, resulting in a larger diameter and increased drilling difficulty. Furthermore, the inner tube of current dual-slurry grouting drill rods has a very small diameter, leading to extremely low work efficiency and failing to meet user needs.

[0003] For example, Chinese Patent Application No. 201920381570.8 discloses a dual-liquid grouting drill rod, which has an inner and outer dual-channel structure. The inner tube of the drill rod is inserted into the central through hole of the outer tube of the drill rod. The central through hole of the inner tube of the drill rod is the first transmission channel, and the annular gap between the outer circumferential surface of the inner tube of the drill rod and the inner circumferential surface of the outer tube of the drill rod is the second transmission channel. However, this invention still has the following disadvantages or deficiencies: (1) The diameter of the second transmission channel of the dual-liquid grouting drill rod is relatively narrow, which makes it difficult to meet the actual grouting requirements; (2) The connection between the inner tube of the drill rod and the outer tube of the drill rod is not very firm.

[0004] Therefore, providing a double-layer grouting drill rod with large inner and outer channel diameters, high grouting efficiency, and strong drill rod connection has become an urgent problem to be solved in the industry. Summary of the Invention

[0005] The purpose of this invention is to provide a double-layer grouting drill rod, which allows for control of the drill rod length, has a large diameter for both the inner and outer channels, and achieves high grouting efficiency.

[0006] To achieve the above objectives, the present invention provides a double-layer grouting drill rod, comprising: an outer tube and an inner tube inserted in the outer tube and coaxial with it, the inner tube and the outer tube being threadedly connected, the middle through hole of the inner tube being an inner channel, the gap between the inner wall of the outer tube and the outer wall of the inner tube being an outer channel, the tail section of the outer tube being provided with a connecting internal thread and a concentric positioning sleeve, and the front section of the outer tube being provided with a connecting external thread matching the connecting internal thread and a concentric positioning shaft matching the concentric positioning sleeve, so that when multiple double-layer grouting drill rods are connected, the connection is achieved through the connecting internal thread and the connecting external thread, and the concentricity and coaxiality are achieved through the concentric positioning sleeve and the concentric positioning shaft.

[0007] Optionally, the outer tube includes an outer tube tail section, an outer tube middle section, and an outer tube front section connected in sequence, and the inner tube includes an inner tube tail section, an inner tube middle section, and an inner tube front section connected in sequence, with the inner tube front section and the outer tube front section being threadedly connected.

[0008] Optionally, the interior of the outer tube tail section is a stepped through hole, including the outer tube tail section, the middle section of the outer tube tail section and the front section of the outer tube tail section with the inner diameter decreasing from back to front. The inner wall of the outer tube tail section is machined with connecting internal threads, the inner wall of the outer tube tail section is provided with a concentric positioning sleeve, the front end of the outer tube tail section is provided with the outer tube first positioning flange, the inner wall of the outer tube tail section is machined into a first positioning hole, and a number of first through holes are provided between the inner wall and the outer wall of the outer tube tail section in a direction parallel to the central axis of the outer tube to form the tail section of the outer channel.

[0009] Preferably, 6 to 12 through holes are drilled between the inner wall and the outer wall of the front part of the outer tube tail section, parallel to the central axis of the outer tube, and evenly distributed along the circumference of the tube.

[0010] Preferably, eight through holes are drilled at equal intervals along the circumference of the outer tube between the inner wall and the outer wall of the front part of the outer tube tail section, parallel to the central axis of the outer tube.

[0011] Optionally, the inner circumferential wall of the middle section of the outer tube matches the first positioning flange of the tail section of the outer tube, and the first positioning flange of the outer tube is inserted into the middle section of the outer tube to achieve a positioning connection between the middle section and the tail section of the outer tube. The annular gap between the inner circumferential wall of the middle section of the outer tube and the outer circumferential wall of the middle section of the inner tube forms the middle section of the outer channel, and the middle section of the outer channel is connected to the tail section of the outer channel.

[0012] Optionally, the tail end of the front section of the outer tube is provided with a second positioning flange of the outer tube. The second positioning flange of the outer tube matches the inner peripheral wall of the middle section of the outer tube. The second positioning flange of the outer tube is inserted into the middle section of the outer tube to realize the positioning connection between the front section of the outer tube and the middle section of the outer tube.

[0013] Preferably, the front end of the outer tube tail section is provided with a first conical surface, the tail end of the outer tube middle section is provided with a second conical surface, and the front end of the outer tube middle section is provided with a third conical surface. A first V-shaped annular groove is formed between the first conical surface and the second conical surface. The first V-shaped annular groove is welded or an adhesive is applied to achieve a fixed connection between the outer tube middle section and the outer tube tail section.

[0014] Preferably, the tail end of the front section of the outer tube is provided with a fourth conical surface of the outer tube, and a second V-shaped annular groove of the outer tube is formed between the third conical surface of the outer tube and the fourth conical surface of the outer tube. The second V-shaped annular groove of the outer tube is welded or an adhesive is applied to achieve a fixed connection between the front section of the outer tube and the middle section of the outer tube.

[0015] Optionally, the interior of the front section of the outer tube is a stepped through hole, which includes, from back to front, the tail section of the front section of the outer tube with an inner diameter decreasing sequentially, the middle section of the front section of the outer tube, and the front section of the front section of the outer tube. Several second through holes are provided between the inner wall and the outer wall of the front section of the outer tube in a direction parallel to the central axis of the outer tube to form the front section of the outer channel. The front section of the outer channel is connected to the middle section of the outer channel. The inner wall of the middle section of the front section of the outer tube is machined with an outer tube inner connection thread for threaded connection and fixing of the inner tube.

[0016] Preferably, 6 to 12 through holes are drilled between the inner wall and the outer wall of the front section of the outer tube, parallel to the central axis of the outer tube, and evenly distributed along the circumference of the tube.

[0017] Preferably, eight through holes are drilled between the inner and outer walls of the front section of the outer tube, parallel to the central axis of the outer tube, and evenly distributed along the circumference of the tube.

[0018] Preferably, the front end of the outer tube is made into a flared opening so that the front end of the inner tube can be inserted into the front end of the outer tube during installation.

[0019] Alternatively, the outer part of the front section of the outer tube is roughly in the shape of a four-step stepped structure with a gradually decreasing outer diameter. The first step corresponds to the tail and middle of the front section of the outer tube. The front end face of the first step is provided with a first sealing groove for installing a sealing ring. The connecting external thread is provided on the outer wall of the second step. The concentric positioning shaft is provided on the third step. The fourth step forms the inner tube positioning flange, and its front outer wall is provided with a second sealing groove for installing a sealing ring.

[0020] Alternatively, the interior of the inner tube tail section is a stepped through hole, which includes the inner tube tail section, the inner tube tail section middle section and the inner tube tail section front section with the inner diameter decreasing from back to front. The inner wall of the inner tube tail section middle section is machined with disassembly threads.

[0021] Preferably, the inner hole at the tail end of the inner tube is cylindrical.

[0022] Alternatively, the outer side of the inner tube tail section is in the shape of three steps with a gradually decreasing outer diameter. The first step surrounds the outer periphery of the entire tail section and the outer periphery of about half of the middle section of the inner tube tail section. The second step surrounds the outer periphery of the middle section of the other half of the inner tube tail section and the outer periphery of most of the front section of the inner tube tail section. The third step surrounds the outer periphery of the front section of the remaining inner tube tail section.

[0023] Optionally, the front end face of the first step forms a retaining platform, which abuts against the rear end face of the front part of the outer tube when the inner tube is installed inside the outer tube, thereby limiting the inner tube relative to the outer tube. The outer wall of the second step is provided with a third sealing groove for installing a sealing ring. The third step is provided with a first positioning flange of the inner tube and a first conical surface of the inner tube.

[0024] Preferably, the outer surface of the first step can be square or hexagonal, for use with a socket wrench to rotate and install the inner tube.

[0025] Optionally, the tail end of the middle section of the inner tube is provided with a second conical surface of the inner tube, the inner peripheral wall of the middle section of the inner tube matches the first positioning flange of the tail section of the inner tube, the first positioning flange of the tail section of the inner tube is inserted into the middle section of the inner tube to achieve positioning connection between the middle section of the inner tube and the tail section of the inner tube, a first V-shaped annular groove of the inner tube is formed between the first conical surface and the second conical surface of the inner tube, the first V-shaped annular groove of the inner tube is welded or an adhesive is applied to achieve fixed connection between the middle section of the inner tube and the tail section of the inner tube, and the front end of the middle section of the inner tube is provided with a third conical surface of the inner tube to achieve fixed connection between the middle section of the inner tube and the front section of the inner tube.

[0026] Optionally, the tail end of the front section of the inner tube is provided with a second positioning flange and a fourth conical surface of the inner tube. The second positioning flange of the inner tube matches the inner circumferential wall of the middle section of the inner tube. The second positioning flange of the inner tube is inserted into the tube of the middle section of the inner tube to realize the positioning connection between the front section of the inner tube and the middle section of the inner tube. A second V-shaped annular groove of the inner tube is formed between the third conical surface and the fourth conical surface of the inner tube. The second V-shaped annular groove of the inner tube is welded or an adhesive is applied to realize the fixed connection between the front section of the inner tube and the middle section of the inner tube.

[0027] Optionally, the outer wall of the front section of the inner tube is machined with an inner tube external connection thread near the front end, and the inner tube external connection thread matches the outer tube internal connection thread to realize the connection between the front section of the outer tube and the front section of the inner tube. The outer wall of the front section of the inner tube is provided with a fourth sealing groove in the middle for installing a sealing ring.

[0028] Preferably, the outer diameter of the first step of the inner tube tail section is smaller than the inner diameter of the middle part of the outer tube tail section, the outer diameter of the first step of the inner tube tail section is larger than the inner diameter of the first positioning hole at the front of the outer tube tail section and smaller than the diameter of the cylindrical surface where the central axis of several through holes of the outer channel at the front of the outer tube tail section is located, and the outer diameter of the second step of the inner tube tail section, the outer diameter of the middle section of the inner tube and the outer diameter of the front section of the inner tube are all slightly smaller than the inner diameter of the first positioning hole at the front of the outer tube tail section.

[0029] Optionally, the connections between the outer tube tail section and the outer tube middle section, the outer tube middle section and the outer tube front section, the inner tube tail section and the inner tube middle section, and the inner tube middle section and the inner tube front section are respectively connected by threaded engagement.

[0030] Preferably, the inner diameter of the inner tube is set to 15-20 mm, the outer diameter of the outer tube is set to 60-65 mm, the wall thickness of the outer tube is set to 10-15 mm, for example 12 mm, and the wall thickness of the inner tube is set to 1.5-3 mm, for example 2 mm.

[0031] Alternatively, the inner tube may be made of seamless tubing.

[0032] Alternatively, the inner tube can be inserted from the tail of the outer tube. The inner tube can be disassembled at the tail using a socket wrench. If the inner tube and the outer tube are stuck together during disassembly, a threaded tool can be used to forcibly pull the inner tube out.

[0033] Generally, after the inner and outer tubes are installed, the distance between the end of the inner tube and the end of the outer tube is about 50 to 100 millimeters, for example, about 85 millimeters.

[0034] The beneficial effects of this invention are: (1) The length of the drill rod can be controlled. When multiple drill rods are connected, they are connected by internal and external threads to ensure the connection strength of multiple drill rods. The matching use of the concentric positioning sleeve and the concentric positioning shaft ensures the concentricity and coaxiality of multiple drill rods; (2) The inner tube and the outer tube are connected by screw threads, which not only ensures the connection strength, but also achieves the airtightness between the inner tube and the outer tube, and fixes the relative position of the outer tube and the inner tube; (3) The setting of the sealing ring can effectively isolate the inner channel and the outer channel, so that the inner and outer channels are separated and a double-layer grouting channel is formed; (4) The inner tube The size can be set to 15-20 mm, and the outer diameter of the outer tube can be set to 60-65 mm, which effectively expands the diameter of the inner and outer channels and improves the grouting efficiency; (5) The inner and outer tubes adopt a three-section design, and the length of the middle section of the inner and outer tubes can be freely measured, so the overall length of the double-layer grouting drill rod can be freely measured according to the requirements, thus improving the flexibility of use; (6) The middle section of the inner and outer tubes can be directly made of standard seamless steel pipes, and only the front and tail sections of the inner and outer tubes need to be specially manufactured, thereby reducing the manufacturing and use costs. Attached Figure Description

[0035] Figure 1 A schematic diagram of the structure of the double-layer grouting drill rod of the present invention is shown.

[0036] Figure 2 A schematic diagram of the structure of the outer tube of the present invention is shown.

[0037] Figure 3 A schematic diagram of the inner tube of the present invention is shown.

[0038] Figure 4 A schematic diagram of the structure of the outer tube tail section of the present invention is shown.

[0039] Figure 5 A schematic diagram of the structure of the inner tube tail section of the present invention is shown.

[0040] Figure 6 A schematic diagram of the structure of the middle section of the outer tube of the present invention is shown.

[0041] Figure 7 A schematic diagram of the structure of the middle section of the inner tube of the present invention is shown.

[0042] Figure 8A schematic diagram of the structure of the front section of the outer tube of the present invention is shown.

[0043] Figure 9 A schematic diagram of the structure of the front section of the inner tube of the present invention is shown.

[0044] Figure 10 A schematic diagram of the combined structure of the double-layer grouting drill rod of the present invention is shown. Detailed Implementation

[0045] The double-layer grouting drill rod of the present invention will now be described in detail with reference to the accompanying drawings.

[0046] As a non-limiting implementation, such as Figure 1 As shown, the double-layer grouting drill rod of the present invention includes an outer tube 1 and an inner tube 2. The inner tube 2 is inserted into the outer tube 1 and is coaxial with it. The inner tube 2 and the outer tube 1 are threaded together. The through hole in the middle of the inner tube 2 is an inner channel 20. The gap between the inner wall of the outer tube 1 and the outer wall of the inner tube 2 is an outer channel 10. The tail section of the outer tube 1 is provided with a connecting internal thread 11 and a concentric positioning sleeve 13. The front section of the outer tube 1 is provided with a connecting external thread 12 that matches the connecting internal thread 11 and a concentric positioning shaft 14 that matches the concentric positioning sleeve 13. Thus, when multiple double-layer grouting drill rods are connected, they are connected by the connecting internal thread 11 and the connecting external thread 12, and concentricity and coaxiality are achieved by the concentric positioning sleeve 13 and the concentric positioning shaft 14. The outer channel 10 includes a tail section, a middle section and a front section connected in sequence.

[0047] like Figure 2 As shown, the outer tube 1 includes an outer tube tail section 1A, an outer tube middle section 1B, and an outer tube front section 1C connected in sequence. Figure 3 As shown, the inner tube 2 includes an inner tube tail section 2A, an inner tube middle section 2B, and an inner tube front section 2C connected in sequence.

[0048] In this non-limiting embodiment, such as Figure 4 As shown, the interior of the outer tube tail section 1A is a stepped through hole, comprising, from back to front, the outer tube tail section 1A-1, the outer tube tail section middle section 1A-2, and the outer tube tail section front section 1A-3. The inner diameters of the outer tube tail section 1A-1, the outer tube tail section middle section 1A-2, and the outer tube tail section front section 1A-3 decrease sequentially. The inner wall of the outer tube tail section 1A-1 is machined with a connecting internal thread 11. The inner wall of the outer tube tail section middle section 1A-2 is provided with a concentric positioning sleeve 13. The front end of the outer tube tail section front section 1A-3 is provided with an outer tube first positioning flange 101 and an outer tube first conical surface 102. The inner wall of the outer tube tail section front section 1A-3 is machined with a first positioning hole 15. Several first through holes are drilled between the inner and outer walls of the outer tube tail section front section 1A-3, parallel to the central axis of the outer tube, thus forming the tail section of the outer channel 10. In this non-limiting embodiment, there may be 6 to 12 through holes evenly distributed along the circumferential direction of the pipe, such as 8 through holes.

[0049] like Figure 6 As shown, the tail end of the outer tube middle section 1B is provided with a second conical surface 103. The inner circumferential wall of the outer tube middle section 1B matches the first positioning flange 101 of the outer tube tail section 1A. Thus, by inserting the first positioning flange 101 of the outer tube tail section 1A into the outer tube middle section 1B, the positioning connection between the outer tube middle section 1B and the outer tube tail section 1A is achieved. After connection, a first V-shaped annular groove is formed between the first conical surface 102 and the second conical surface 103 of the outer tube. The outer tube middle section 1B and the outer tube tail section 1A are fixedly connected as one unit by welding or applying adhesive to the first V-shaped annular groove. Similarly, the front end of the outer tube middle section 1B is provided with a third conical surface 104 for fixed connection between the outer tube middle section 1B and the outer tube front section 1C. The annular gap between the inner circumferential wall of the outer tube middle section 1B and the outer circumferential wall of the inner tube middle section 2B forms the middle section of the outer channel 10.

[0050] like Figure 8 As shown, the tail end of the outer tube front section 1C is provided with an outer tube second positioning flange 105 and an outer tube fourth conical surface 106. The outer tube second positioning flange 105 matches the inner peripheral wall of the outer tube middle section 1B. Thus, by inserting the outer tube second positioning flange 105 into the outer tube middle section 1B, the positioning connection between the outer tube front section 1C and the outer tube middle section 1B is achieved. After connection, an outer tube second V-shaped annular groove will be formed between the outer tube third conical surface 104 and the outer tube fourth conical surface 106. The outer tube front section 1C and the outer tube middle section 1B are fixedly connected as one unit by welding or applying adhesive to the outer tube second V-shaped annular groove.

[0051] The interior of the front section 1C of the outer tube is a stepped through hole, comprising, from back to front, the tail section 1C-1, the middle section 1C-2, and the front section 1C-3 of the outer tube, with the inner diameters of the tail section 1C-1, the middle section 1C-2, and the front section 1C-3 decreasing sequentially. Several second through holes are drilled between the inner and outer walls of the front section 1C, parallel to the central axis of the outer tube, thus forming the front section of the outer channel 10. In this non-limiting embodiment, 6 to 12 through holes, such as 8, may be evenly spaced along the circumference of the tube. The inner wall of the middle section 1C-2 of the outer tube is machined with an inner tube connection thread 18 for threaded connection and fixation of the inner tube 2. In this non-limiting embodiment, the tail section 1C-1 of the outer tube is made into a flared opening to facilitate insertion of the front end of the inner tube 2 into the tail section 1C-1 of the outer tube during installation.

[0052] In this non-limiting embodiment, the outer part of the front section 1C of the outer tube is generally in the shape of a four-step structure with a gradually decreasing outer diameter. The first step S1 corresponds to the tail part 1C-1 and the middle part 1C-2 of the front section of the outer tube. The front end face of the first step S1 is provided with a first sealing groove F1 for installing a sealing ring. The connecting external thread 12 is provided on the outer wall of the second step S2. The concentric positioning shaft 14 is provided on the third step S3. The fourth step S4 forms an inner tube positioning flange, and the outer wall of its front end is provided with a second sealing groove F2 for installing a sealing ring.

[0053] like Figure 5 As shown, the interior of the inner tube tail section 2A is also a stepped through hole, comprising, from back to front, the inner tube tail section 2A-1, the inner tube tail section middle section 2A-2, and the inner tube tail section front section 2A-3. The inner diameters of the inner tube tail section 2A-1, the inner tube tail section middle section 2A-2, and the inner tube tail section front section 2A-3 decrease sequentially. The inner wall of the inner tube tail section middle section 2A-2 is machined with a disassembly thread 16, which is used when disassembling the inner tube. In this non-limiting embodiment, the inner hole of the inner tube tail section 2A-1 is cylindrical.

[0054] The outer surface of the inner tube tail section 2A is roughly in the shape of three steps with a gradually decreasing outer diameter. The first step T1 surrounds the entire outer perimeter of the inner tube tail section 2A-1 and approximately half of the inner tube tail section middle section 2A-2. The second step T2 surrounds the outer perimeter of the other half of the inner tube tail section middle section 2A-2 and most of the outer perimeter of the inner tube tail section front section 2A-3. The third step T3 surrounds the outer perimeter of the remaining inner tube tail section front section 2A-3. The front end face of the first step T1 forms a retaining plate 17, which is used to limit the inner tube 2 relative to the outer tube 1 by abutting against the rear end face of the outer tube tail section front section 1A-3 when the inner tube 2 is installed inside the outer tube 1. The outer wall of the second step T2 is provided with a sealing groove F3 for installing a sealing ring. The third step T3 forms the inner tube first positioning flange 201 and the inner tube first conical surface 202. In this non-limiting embodiment, the outer surface of the first step T1 may be square or hexagonal, for use with a socket wrench to rotate and install the inner tube 2.

[0055] like Figure 7As shown, the tail end of the inner tube middle section 2B is provided with an inner tube second conical surface 203. The inner peripheral wall of the inner tube middle section 2B matches the inner tube first positioning flange 201 of the inner tube tail section 2A. Thus, by inserting the inner tube first positioning flange 201 of the inner tube tail section 2A into the inner tube middle section 2B, the positioning connection between the inner tube middle section 2B and the inner tube tail section 2A is achieved. After connection, an inner tube first V-shaped annular groove is formed between the inner tube first conical surface 202 and the inner tube second conical surface 203. The inner tube middle section 2B and the inner tube tail section 2A are fixedly connected as one unit by welding or applying adhesive to the inner tube first V-shaped annular groove. Similarly, the front end of the inner tube middle section 2B is provided with an inner tube third conical surface 204, which is used to achieve a fixed connection between the inner tube middle section 2B and the inner tube front section 2C.

[0056] like Figure 9 As shown, the tail end of the inner tube front section 2C is provided with an inner tube second positioning flange 205 and an inner tube fourth conical surface 206. The inner tube second positioning flange 205 matches the inner peripheral wall of the inner tube middle section 2B. Thus, by inserting the inner tube second positioning flange 205 into the inner tube middle section 2B, the positioning connection between the inner tube front section 2C and the inner tube middle section 2B is achieved. After connection, an inner tube second V-shaped annular groove will be formed between the inner tube third conical surface 204 and the inner tube fourth conical surface 206. The inner tube front section 2C and the inner tube middle section 2B are fixedly connected as one unit by welding or applying adhesive to the inner tube second V-shaped annular groove.

[0057] The outer wall of the inner tube front section 2C has an inner tube external connection thread 19 near the front end. The inner tube external connection thread 19 matches the outer tube internal connection thread 18. The connection between the outer tube front section 1C and the inner tube front section 2C is achieved through the threaded connection, thereby realizing the connection and fixation between the inner tube 2 and the outer tube 1. The outer wall of the inner tube front section 2C has a sealing groove F4 in the middle for installing a sealing ring.

[0058] Thus, an outer tube 1 is formed by sequentially connecting the outer tube tail section 1A, the outer tube middle section 1B, and the outer tube front section 1C and then fixing them by welding or bonding. An inner tube 2 is formed by sequentially connecting the inner tube tail section 2A, the inner tube middle section 2B, and the inner tube front section 2C and then fixing them by welding or bonding. The inner tube 2 is then inserted into the outer tube 1 from the tail end of the outer tube tail section 1A. The inner tube front section 2C of the inner tube 2 passes sequentially through the outer tube tail section 1A, the outer tube middle section 1B, and the outer tube front section tail 1C-1 of the outer tube front section 1C. Finally, by rotating the inner tube 2, the inner tube external connection thread 19 of the inner tube front section 2C is threadedly connected and fixed to the outer tube internal connection thread 18 of the outer tube middle section 1C-2 of the outer tube front section, thereby fixing the inner tube 2 inside the outer tube 1. After installation, the locking platform 17 of the inner tube tail section 2A abuts against the rear end face of the outer tube tail section front 1A-3 to limit the inner tube 2 relative to the outer tube 1. The sealing ring installed in the sealing groove F3 at the inner tube tail section 2A seals against the inner circumferential wall of the first positioning hole 15 at the outer tube tail section front 1A-3, and the sealing ring installed in the sealing groove F4 at the inner tube front section 2C seals against the inner circumferential wall of the outer tube tail section front 1C-1, thus achieving a sealed isolation between the inner channel 20 and the outer channel 10.

[0059] Please refer to Figure 10 A double-layer grouting drill rod is obtained by installing an inner tube 2 into an outer tube 1. During grouting, multiple double-layer grouting drill rods are sequentially rotated and threaded together as needed. Specifically, the inner tube positioning flange at the fourth step S4 of the outer tube front section 1C of one double-layer grouting drill rod is inserted into the inner tube tail section 2A-1 of the inner tube tail section 2A of another double-layer grouting drill rod. The sealing ring installed in the second sealing groove F2 achieves a seal with the inner wall of the inner tube tail section 2A-1, thereby achieving a sealed isolation between the inner channel 20 and the outer channel 10. The concentric positioning shaft 14 at the third step S3 of the outer tube front section 1C of one double-layer grouting drill rod is installed in the concentric positioning sleeve 13 in the middle 1A-2 of the outer tube tail section 1A of another double-layer grouting drill rod, to achieve concentricity and coaxiality between the two double-layer grouting drill rods. The external thread 12 at the second step S2 of the outer tube front section 1C of one double-layer grouting drill rod is threaded to the internal thread 11 at the tail end 1A-1 of the outer tube tail section 1A of another double-layer grouting drill rod, so as to realize the threaded fixed connection between one double-layer grouting drill rod and another double-layer grouting drill rod; the sealing ring installed in the first sealing groove F1 at the first step S1 of the outer tube front section 1C of one double-layer grouting drill rod is used to achieve a sealing fit with the tail end face of the outer tube tail section 1A of another double-layer grouting drill rod, thereby realizing the sealing isolation between the inner channel 20 and the outer channel 10 of the two adjacent double-layer grouting drill rods, as well as the sealing isolation between the outer channel 10 and the outside of the grouting drill rod.

[0060] In this non-limiting embodiment, such as Figures 2-5 As shown, the maximum outer diameter of the first step T1 of the inner tube tail section 2A is smaller than the inner diameter of the middle section 1A-2 of the outer tube tail section. Simultaneously, the maximum outer diameter of the first step T1 of the inner tube tail section 2A is larger than the inner diameter of the first positioning hole 15 of the front section 1A-3 of the outer tube tail section and smaller than the diameter of the cylindrical surface containing the central axis of several through holes of the outer channel 10 of the front section 1A-3 of the outer tube tail section. This allows the locking platform 17 of the inner tube tail section 2A to abut against the rear end face of the front section 1A-3 of the outer tube tail section, thus limiting the inner tube 2 relative to the outer tube 1 without affecting the flow of grout in the outer channel 10. Furthermore, the outer diameter of the second step T2 of the inner tube tail section 2A, the outer diameter of the middle section 2B of the inner tube, and the outer diameter of the front section 2C of the inner tube are all slightly smaller than the inner diameter of the first positioning hole 15 of the front section 1A-3 of the outer tube tail section, so that the inner tube 2 can be smoothly inserted and fixed inside the outer tube 1.

[0061] To achieve the connection, such as Figure 1 and Figure 10 As shown, during installation, the inner tube 2 is inserted from the tail of the outer tube 1. The inner tube 2 is removed and installed at the tail using a sleeve wrench. If the inner tube and the outer tube are stuck together during disassembly, a threaded tool can be used to forcibly pull out the inner tube 2.

[0062] Therefore, the double-layer grouting drill rod of the present invention is assembled from an outer tube and an inner tube. The tail of the outer tube is provided with an internal thread and a concentric positioning sleeve, and the front is provided with an external thread and a concentric positioning shaft. When multiple drill rods are connected, the internal and external threads are connected to ensure the connection strength and concentricity of the multiple drill rods. The inner tube is made of seamless tube and is inserted from the tail of the outer tube and threadedly connected to the outer tube, isolating the inner and outer channels and forming a double grout channel. The sealing ring not only isolates the inner and outer channels to form a double grout channel, but also prevents the grout in the outer channel from flowing out after the two drill rods are installed.

[0063] Although preferred embodiments of the invention have been described in detail herein, it should be understood that the invention is not limited to the specific structures and steps described and shown herein, and other variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. A double-layer grouting drill rod, characterized in that, It includes: an outer tube and an inner tube inserted into the outer tube and coaxial with it, the inner tube and the outer tube being threadedly connected, the middle through hole of the inner tube being an inner channel, the gap between the inner wall of the outer tube and the outer wall of the inner tube being an outer channel, the tail section of the outer tube being provided with a connecting internal thread and a concentric positioning sleeve, and the front section of the outer tube being provided with a connecting external thread matching the connecting internal thread and a concentric positioning shaft matching the concentric positioning sleeve, so that when multiple double-layer grouting drill rods are connected, the connection is achieved through the connecting internal thread and the connecting external thread, and the concentricity and coaxiality are achieved through the concentric positioning sleeve and the concentric positioning shaft; The outer tube includes an outer tube tail section, an outer tube middle section, and an outer tube front section connected in sequence, and the inner tube includes an inner tube tail section, an inner tube middle section, and an inner tube front section connected in sequence, with the inner tube front section being threadedly connected to the outer tube front section. The outer tube tail section has a stepped through hole inside, and from back to front includes an outer tube tail section with an inner diameter decreasing sequentially, an outer tube tail section middle section, and an outer tube tail section front section. The inner wall of the outer tube tail section tail section is machined with the connecting internal thread, the inner wall of the outer tube tail section middle section is provided with the concentric positioning sleeve, the front end of the outer tube tail section front section is provided with an outer tube first positioning flange, the inner wall of the outer tube tail section front section is machined with a first positioning hole, and a plurality of first through holes are provided between the inner wall and the outer wall of the outer tube front section parallel to the outer tube central axis to form the tail section of the outer channel. The front section of the outer tube has a stepped through hole inside, and from back to front includes a tail section of the front section of the outer tube with an inner diameter that decreases sequentially, a middle section of the front section of the outer tube, and a front section of the front section of the outer tube. The inner wall and outer wall of the front section of the outer tube are provided with a plurality of second through holes parallel to the central axis of the outer tube to form the front section of the outer channel. The front section of the outer channel is connected to the middle section of the outer channel. The inner wall of the middle section of the front section of the outer tube is machined with an outer tube internal connection thread for threaded connection and fixing of the inner tube. The outer side of the inner tube tail section is in the shape of three steps with a gradually decreasing outer diameter. The front end face of the first step forms a retaining platform, which is used to limit the inner tube relative to the outer tube by abutting against the rear end face of the front part of the outer tube tail section when the inner tube is installed in the outer tube. The outer wall of the second step is provided with a third sealing groove for installing a sealing ring, and a first positioning flange of the inner tube is formed at the third step. The outer wall of the front section of the inner tube is machined with an inner tube external connection thread near the front end. The inner tube external connection thread matches the outer tube internal connection thread to realize the connection between the front section of the outer tube and the front section of the inner tube. The outer wall of the front section of the inner tube is provided with a fourth sealing groove in the middle for installing a sealing ring.

2. The double-layer grouting drill rod as described in claim 1, characterized in that, The inner peripheral wall of the middle section of the outer tube matches the first positioning flange of the tail section of the outer tube. The first positioning flange of the outer tube is inserted into the middle section of the outer tube to achieve positioning connection between the middle section of the outer tube and the tail section of the outer tube. The annular gap between the inner peripheral wall of the middle section of the outer tube and the outer peripheral wall of the middle section of the inner tube forms the middle section of the outer channel. The middle section of the outer channel is connected to the tail section of the outer channel.

3. The double-layer grouting drill rod as described in claim 2, characterized in that, The front end of the outer tube is provided with a second positioning flange, which matches the inner circumferential wall of the middle section of the outer tube. The second positioning flange is inserted into the middle section of the outer tube to achieve a positioning connection between the front section and the middle section of the outer tube.

4. The double-layer grouting drill rod as described in claim 1, characterized in that, The outer section of the outer tube has a four-step shape with a gradually decreasing outer diameter. The first step corresponds to the tail and middle of the outer tube. The front end face of the first step is provided with a first sealing groove for installing a sealing ring. The connecting external thread is provided on the outer wall of the second step. The concentric positioning shaft is provided on the third step. The fourth step forms an inner tube positioning flange. The outer wall of the front end of the inner tube positioning flange is provided with a second sealing groove for installing a sealing ring.

5. The double-layer grouting drill rod as described in claim 1, characterized in that, The interior of the inner tube tail section is a stepped through hole, which includes the inner tube tail section, the inner tube tail section middle section and the inner tube tail section front section with the inner diameter decreasing from back to front. The inner wall of the inner tube tail section middle section is machined with disassembly threads.

6. The double-layer grouting drill rod as described in claim 5, characterized in that, The inner peripheral wall of the middle section of the inner tube matches the first positioning flange of the tail section of the inner tube. The first positioning flange of the tail section of the inner tube is inserted into the middle section of the inner tube to achieve a positioning connection between the middle section of the inner tube and the tail section of the inner tube.

7. The double-layer grouting drill rod as described in claim 6, characterized in that, The front end of the inner tube is provided with a second positioning flange, which matches the inner circumferential wall of the middle section of the inner tube. The second positioning flange is inserted into the middle section of the inner tube to achieve a positioning connection between the front section and the middle section of the inner tube.

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