Welded shield pressure relief drill rod for outburst coal seam and sealing assembly method of welded shield pressure relief drill rod

Abstract

The outburst coal seam welding type shield protection pressure relief drill rod comprises a strip-hole outer pipe, a strip-hole inner pipe is arranged in the strip-hole outer pipe, and a slag inlet plate is arranged at a first strip-shaped hole or a round hole in the pipe wall of the strip-hole outer pipe; an axial flow supply channel flowing in the drill bit direction is formed between the inner wall of the strip-hole outer pipe and the outer wall of the strip-hole inner pipe, a center hole of the strip-hole inner pipe forms a slag discharging channel, the flow direction of the slag discharging channel is opposite to that of the axial flow supply channel, and the slag discharging channel and the axial flow supply channel are isolated from each other. The pipe walls of the strip-hole outer pipe and the strip-hole inner pipe are provided with slag inlet channels which are communicated with the slag inlet holes and the slag discharge channel; the method has the beneficial effects that welding seam sealing is adopted, the sealing problem between the radial slag inlet channel and the axial flow supply channel is solved, the overall strength of the drill rod is improved, and insertion sealing between the inner pipes of the drill rod is more reliable through the detachable and reusable positioning tool.

Description

Technical Field

[0001] The present invention relates to the technical field of gas drainage boreholes in outburst coal seams, and particularly to a welded shielded pressure-relief drill pipe for outburst coal seams and its sealing assembly method. Background Art

[0002] At present, the drill pipes used for drilling along the coal seams in soft outburst coal seams in China mainly include grooved drill pipes, ribbed drill pipes and prismatic grooved drill pipes, with the patent numbers being: ZL200610111830.7, ZL200920088879.4, ZL200910064973.0 respectively, and the applicant being Henan Polytechnic University. The technical features of these three patents are mainly reflected in the improvement of the outer shape of the drill pipe. By setting spiral grooves, spiral ribs and axial edges on the outer surface of the drill pipe, the slag discharge effect of the drill pipe is improved. The improvement of the outer shape of these drill pipes has also been transplanted to the cable-connected drill pipes and cable-free drill pipes used for directional drilling, and has been adopted in China for about eighteen years, which has played a certain role in improving the slag discharge effect and increasing the drilling depth. The common feature of these drill pipes is that air flow, water flow or air-water linkage is used as the slag discharge medium. The annular space between the outer surface of the drill pipe and the borehole wall is the slag discharge channel, referred to as the external slag discharge channel for short. The central hole of the drill pipe is the flow supply channel, supplying air flow or water flow to the drill bit. For outburst coal seams, the outer wall of the external slag discharge channel is soft coal body with a relatively high gas pressure gradient and extremely easy to collapse. Drilling dynamic phenomena such as ground stress, coal bumps and outburst holes can all cause the collapse, caving and blockage of the external slag discharge channel. The external slag discharge channel is a very unstable slag discharge channel, and the difficult slag discharge is the fundamental reason for the difficult drilling in soft outburst coal seams. In addition, due to the existence of the external slag discharge channel, the diameter of the drill pipe must be smaller than the diameter of the drill bit, and the disturbance space of the drill pipe is relatively large, resulting in serious borehole deviation. Although the directional drilling technology can solve the problem of borehole deviation, since the drilling in soft outburst coal seams is also difficult, and the cost of pressing the drill and losing the drill of the directional drilling tool is too high, the directional drilling technology is rarely used in soft outburst coal seams. The depth of the boreholes drilled along the coal seams in soft outburst coal seams is shallow and the borehole deviation is serious. It is forced to construct cross-cut boreholes in the floor rock roadway to eliminate the extraction blind area, resulting in a high cost of gas control in outburst mines, which has become a recognized problem in gas extraction and gas control in soft outburst coal seams.

[0003] In view of the problems of difficult slag discharge, shallow drilling depth, and serious drilling deviation in soft outburst coal seams, the applicant proposed the drilling idea of "shield protection and pressure relief drilling". The core content includes: First, abandon the external slag discharge channel and construct an internal slag discharge channel inside the drill pipe to solve the problem of difficult slag discharge in soft outburst coal seams; Second, abandon the external slag discharge channel. If conditions permit, make the diameter of the drill pipe equal to or close to the diameter of the drill bit, limit the disturbance space of the drill pipe, and then reduce the drilling deviation. Reducing the drilling deviation is not only beneficial to deep hole drilling but also beneficial to accurately eliminating the extraction blind area; Third, pressuring and jamming the drill is a common phenomenon in drilling in soft outburst coal seams. Only 20%-30% of the drill slag in soft outburst coal seams comes from the drill bit, and 70%-80% of the drill slag comes from the deformation and damage of the borehole wall. It is necessary to set up a radial slag discharge and pressure relief channel in the radial direction of the drill pipe to enable the drill pipe to have the function of self-pressure relief. To implement the above drilling idea, a drill pipe with a special structure needs to be designed. The structural characteristics of the drill pipe are: a ring-shaped flow supply channel is set in the axial direction of the drill pipe, an axial internal slag discharge channel is set in the axial center of the drill pipe, and a slag discharge and pressure relief channel composed of numerous radial holes is set in the radial direction of the drill pipe.

[0004] Based on the above drilling idea and drill pipe structure, the applicant has applied for a number of patents successively. The application numbers are: 202110726041.9; 202110903532.6; 202111152968.2; 202111237232.5; 202210013684.3; 202210249463.6; CN202311137536.3. These patents mention the problems of "interfitting and sealing between the outer pipe and the inner pipe" and "coaxial positioning between the outer pipe and the inner pipe". The former is the need for isolation and sealing of the "radial slag inlet channel and the axial flow supply channel", and the latter is the need for plug-in sealing between the "inner pipes" after the drill pipes are connected. The method given for the former is glue-applied interfitting and sealing, and the method given for the latter is to use a detachable and reusable positioning ring to achieve coaxial positioning, so as to achieve coaxial plug-in sealing between the inner pipes. We found the following defects still exist during the actual trial production process: First, even for precision cold-drawn steel pipes, there are still large errors in wall thickness, pore diameter, straightness, etc. This makes it very difficult to insert and fit the inner pipe and the outer pipe. If a large insertion gap is designed in advance, although the insertion and fitting problem can be solved, it will lead to a decrease in the reliability of glue sealing, because the thicker the glue layer, the worse the sealing effect, that is, it is difficult to isolate and seal the "radial slag inlet channel and the axial flow supply channel".

[0005] Second, the glue layer does not have the ability to resist torsion and shear. Under the interference of the torque and heat of the drill pipe, the glue layer is prone to aging and detachment. This will not only cause air leakage between the "radial slag inlet channel and the axial flow supply channel", but also cause the coaxial positioning between the inner and outer pipes to fail, and then cause the plug-in sealing between the inner pipes to fail, that is, cause air leakage between the "axial flow supply channel and the axial internal slag discharge channel". Summary of the Invention

[0006] The object of the present invention is to provide a welded shielded pressure relief drill pipe for outburst coal seams and its sealing assembly method. Aiming at the problems existing in the prior art, the large-gap glue-sealing process is cancelled, and it is changed to welding and sealing after positioning by a tooling, so as to achieve precise circumferential positioning, axial positioning and coaxial positioning, and at the same time improve the overall torsional strength of the drill pipe.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A welded shielded pressure relief drill pipe for outburst coal seams includes a slotted outer pipe, a slotted inner pipe is arranged inside the slotted outer pipe, and a slag inlet plate is arranged at the first strip hole or round hole on the pipe wall of the slotted outer pipe; An axial flow supply channel flowing towards the drill bit is formed between the inner wall of the slotted outer pipe and the outer wall of the slotted inner pipe, and a slag discharge channel flowing in the opposite direction to the axial flow supply channel and isolated from each other is formed in the central hole of the slotted inner pipe. A through slag inlet hole is opened on the slag inlet plate, and a slag inlet channel communicating the slag inlet hole with the slag discharge channel is opened on the pipe walls of the slotted outer pipe and the slotted inner pipe.

[0008] Furthermore, one or a plurality of spiral grooves evenly distributed in the circumferential direction and a plurality of axial grooves evenly distributed in the circumferential direction are arranged on the outer surface of the slotted outer pipe. A female thread and a male thread that can be connected to the female thread of another slotted outer pipe are respectively arranged at both ends of the slotted outer pipe, and a thread sealing ring is arranged at the root of the female thread.

[0009] Furthermore, the two ends of the slotted inner pipe are respectively processed into a female end round pipe and a male end round pipe that can be connected to the female end round pipe of another slotted inner pipe, and a special-shaped sealing ring is arranged on the female end round pipe.

[0010] Furthermore, at least one first strip hole is opened on the slotted outer pipe, a convex rib is arranged on the slotted inner pipe, and a second strip hole corresponding to the first strip hole one by one is opened on the convex rib.

[0011] Furthermore, at least one first positioning hole is opened on the slotted outer pipe, and a second positioning hole corresponding to the first positioning hole one by one is opened on the convex rib.

[0012] Furthermore, the slag inlet plate is installed in the first strip hole, the slag inlet hole is a tapered hole, and the opening on the larger side of the tapered hole faces the center of the slotted outer pipe.

[0013] Furthermore, the present invention also provides a sealing assembly method for the welded shielded pressure relief drill pipe for outburst coal seams. Based on the aforementioned welded shielded pressure relief drill pipe for outburst coal seams, it includes the following steps: S1. Insert the inner pipe with strip holes into the inner cavity of the outer pipe with strip holes, and place the female end circular pipe on the side of the female thread. Then, use the strip hole alignment die to preliminarily align the first strip hole with the second strip hole, and align the end face of the male end circular pipe with the end face of the male thread side of the outer pipe with strip holes; S2. Place a female end coaxial positioning ring between the female end circular pipe and the female thread, and place a male end coaxial positioning ring between the male end circular pipe and the male thread, so as to adjust the radial positions of the female end circular pipe and the male end circular pipe to make them coaxial with the female thread and the male thread respectively; S3. Drill a second positioning hole based on the first positioning hole and anchor a bearing positioning pin to fasten the inner pipe with strip holes and the outer pipe with strip holes to each other. Then, remove the strip hole alignment die; S4. Use the first strip hole as the welding torch inlet to seal-weld the contact seam between the first strip hole and the second strip hole; S5. Heat-treat the semi-finished drill pipe after the seal-welding to eliminate internal stress, and remove the female end coaxial positioning ring and the male end coaxial positioning ring for coaxial positioning; S6. Install a special-shaped sealing ring and a screw thread sealing ring, and conduct batch pressure testing on the semi-finished drill pipe after heat treatment; S7. For the semi-finished drill pipe with qualified pressure resistance, install the slag inlet plate into the first strip hole.

[0014] Furthermore, in S7, the slag inlet plate and the outer pipe with strip holes are fixed by inserting and then spot-welding.

[0015] Furthermore, for the semi-finished drill pipe with unqualified sealing pressure resistance in S6, repair welding treatment needs to be carried out until the pressure resistance reaches the standard.

[0016] The beneficial effects of the present invention are as follows: 1. A relatively large gap is pre-designed between the inner pipe with strip holes and the outer pipe with strip holes, so that the inner pipe and the outer pipe can be easily inserted, and the insertion of the inner and outer pipes can be conveniently realized; at the same time, the reliable isolation between the axial flow supply channel flow direction and the slag discharge channel can be realized.

[0017] 2. Utilize the gap between the inner pipe and the outer pipe, cooperate with the recyclable positioning tooling, realize circumferential positioning, axial positioning and coaxial positioning, and realize the preliminary positioning between the inner pipe with the tooling and the outer pipe; at the same time, change the circular holes on the inner pipe and the outer pipe to strip holes, create space for the use of the welding torch, and replace the glue sealing with weld sealing to realize the reliable sealing of the "radial slag inlet channel and the axial flow supply channel".

[0018] 3. Heat-treat the semi-finished product after welding to remove the welding stress, and then remove the positioning tooling to realize the final positioning between the inner pipes, that is, realize the reliable sealing between the "axial flow supply channel and the axial inner slag discharge channel".

[0019] 4. The large-gap glue coating sealing process is cancelled and replaced by welding and sealing after tooling positioning. While achieving precise circumferential positioning, axial positioning, and coaxial positioning, the overall torsional strength of the drill pipe can be improved. In addition, the assembly difficulty is reduced and the processing efficiency is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the overall structure diagram of the welded shielded pressure-relief drill pipe in Embodiment 1; Figure 2 It is the structural schematic diagram of the slotted outer pipe in Embodiment 1; Figure 3 It is the structural schematic diagram of the slotted inner pipe in Embodiment 1; Figure 4 It is the structure diagram of the slag inlet plate in Embodiment 1; Figure 5 It is the assembly schematic diagram of the welded shielded pressure-relief drill pipe in Embodiment 1; Figure 6 It is the schematic diagram of the connection and sealing method of the slotted inner pipe and the slotted outer pipe in Embodiment 1; Figure 7 It is the external structure diagram of the welded shielded pressure-relief drill pipe in other embodiments; Figure 8 It is the cross-sectional view of the welded shielded pressure-relief drill pipe in other embodiments; Figure 9 It is the structural schematic diagram of the slag inlet plate in other embodiments.

[0021] The drawings are only for illustrative purposes and should not be construed as a limitation of this patent; for better illustration of this embodiment, some components in the drawings are omitted, enlarged, or reduced, and do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present invention will be further described below with reference to the drawings.

[0023] Embodiment 1 As Figure 1 and Figure 5 shown, the welded shielded pressure-relief drill pipe for outburst coal seams in this embodiment includes a slotted outer pipe 1. The outer diameter of the slotted inner pipe 2 is smaller than the inner diameter of the slotted outer pipe 1. The axial length of the slotted inner pipe 2 is slightly smaller than the axial length of the slotted outer pipe 1, and the two are coaxial. The slotted inner pipe 2 is placed in the inner cavity of the slotted outer pipe 1. A slag inlet plate 3 is arranged at the first strip hole 11 on the wall of the slotted outer pipe 1; An axial fluid supply channel 4 flowing towards the drill bit is formed between the inner wall of the strip-hole outer pipe 1 and the outer wall of the strip-hole inner pipe 2. The central hole of the strip-hole inner pipe 2 forms a slag discharge channel 5 that flows in the opposite direction to the axial fluid supply channel 4 and is isolated from each other. During the working process of the drill pipe, fluid is supplied to the drill bit through the axial fluid supply channel 4, and at the same time, the slag generated at the drill bit can be discharged along the slag discharge channel 5. The feed plate 3 is provided with a through feed hole 31, and a feed channel 6 connecting the feed hole 31 and the slag discharge channel 5 is radially provided on the circumferential walls of the strip-hole outer pipe 1 and the strip-hole inner pipe 2. The slag around the drill pipe can flow along the feed hole 31 and the feed channel 6, and finally enter the slag discharge channel 5 and be discharged.

[0024] As Figure 2 shown, three spiral grooves 13 and axial grooves 17 with a certain depth are circumferentially arrayed on the outer surface of the strip-hole outer pipe 1. The two ends of the strip-hole outer pipe 1 are respectively provided with a female thread 14 and a male thread 15 that can be connected to the female thread 14 of another strip-hole outer pipe 1. A thread seal ring 16 is provided at the root of the female thread 14.

[0025] As Figure 3 shown, the two ends of the strip-hole inner pipe 2 are respectively processed into a female end circular pipe 24 and a male end circular pipe 25 that can be connected to the female end circular pipe 24 of another strip-hole inner pipe 2. A special-shaped seal ring 21 is provided on the female end circular pipe 24.

[0026] In the actual use process, due to the relatively deep drilling, multiple strip-hole outer pipes 1 and strip-hole inner pipes 2 need to be assembled and used. The strip-hole outer pipes 1 are sequentially connected through the female threads 14 and male threads 15 at their two ends, and are sealed by the thread seal rings 16. The strip-hole inner pipes 2 are sequentially connected through the female end circular pipes 24 and male end circular pipes 25 at their two ends, and are sealed by the special-shaped seal rings 21. As Figure 6 shown, it is a schematic diagram of the connection and sealing method of the strip-hole inner pipe and the strip-hole outer pipe. In this embodiment, as shown in 6-a, a thread seal ring 16 is arranged at the end of the female thread 14, and the male thread 15 is screwed in and sealed by relying on this thread seal ring 16. When the drill pipes are butted, the strip-hole inner pipes 2 in the inner cavity are also butted and sealed in sequence. A special-shaped seal ring 21 is installed on the female end circular pipe 24 at one end of the strip-hole inner pipe 2 to achieve overlapping and staggered butt joint sealing with the male end circular pipe 25 of another butted strip-hole inner pipe 2; in some embodiments, as shown in 6-b, the sealing method of the thread seal ring 16 remains unchanged, the special-shaped seal ring 21 is changed to a common seal ring, a sealing groove is processed on the inner side of the female end circular pipe 24, and the common seal ring is installed. When butting with another strip-hole inner pipe 2, inserting the male end circular pipe 25 can achieve sealing.

[0027] After the inner pipe 2 with strip holes is inserted into the outer pipe 1 with strip holes and positioned using a positioning tooling, it is necessary to ensure that the end face of the male end circular pipe 25 of the inner pipe 2 with strip holes is aligned with the end face of the male thread 15 of the outer pipe 1 with strip holes, so that the inner pipe 2 with strip holes is welded in the inner cavity of the outer pipe 1 with strip holes, and the slag inlet channel 6 and the fluid supply channel 4 are sealed and isolated from each other.

[0028] As Figure 2 and Figure 3 shown, on the outer pipe 1 with strip holes, three first strip holes 11 are evenly distributed in a circumferential direction near the female thread 14. Taking the three first strip holes 11 evenly distributed in a circumferential direction as a group, six groups of first strip holes 11 are then arranged at a certain interval along the axial direction. In the specific implementation process, the number of the first strip holes 11 can be arranged more to achieve the maximum slag inlet efficiency on the premise of meeting the application strength safety of the drill pipe. Three ribs are provided on the inner pipe 2 with strip holes, and second strip holes 22 corresponding one by one to the three first strip holes 11 in each group are opened on the three ribs.

[0029] In some embodiments, the first strip holes 11 can also be changed to round holes, that is, the first slag inlet round holes. Correspondingly, the second strip holes 22 also need to be changed to round holes accordingly, that is, the second slag inlet round holes. The first strip holes 11 and the first slag inlet round holes are both opened on the axial groove 17.

[0030] To ensure the implementation of the welding and sealing process, when opening the strip holes, the width of the second strip holes 22 needs to be slightly smaller than the width of the first strip holes 11, and the length of the second strip holes 22 needs to be slightly smaller than the length of the first strip holes 11; when opening the round holes, the diameter of the second slag inlet round holes needs to be smaller than the diameter of the first slag inlet round holes.

[0031] In other embodiments, the number of each group of first strip holes 11 or the first slag inlet round holes can also be set to two, four or other numbers, and all should be included in the protection scope of this application.

[0032] Three groups of first positioning holes 12 are opened on the outer pipe 1 with strip holes (each group includes three, corresponding one by one to the three first strip holes 11 respectively), and second positioning holes 23 corresponding one by one to the first positioning holes 12 are opened on the ribs.

[0033] In this embodiment, the inner hole of the outer pipe 1 with strip holes is circular. In some embodiments, its inner hole can also be polygonal or other special-shaped forms, and all should be included in the protection scope of this application.

[0034] As Figure 4As shown, the slag inlet plate 3 is a special-shaped strip. The slag inlet plate 3 is installed in the first strip hole 11. The slag inlet hole 31 is a tapered hole, and the opening on the larger side of the tapered hole faces the center of the strip hole outer tube 1 (that is, the small hole faces outward to avoid slag inlet blockage). The outer contour size of the slag inlet plate 3 matches the size of the first strip hole 11 (it can just be inserted into the first strip hole 11), so that they can be fitted and installed.

[0035] As Figure 5 shown, this embodiment also proposes a sealing assembly method for the welded shield pressure relief drill pipe in outburst coal seams. Based on the aforementioned welded shield pressure relief drill pipe in outburst coal seams, it includes the following steps: S1. Insert the strip hole inner tube 2 into the inner cavity of the strip hole outer tube 1, and the female end round tube 24 is located on one side of the female thread 14, and align the end face of the male end round tube 25 of the strip hole inner tube 2 with the end face of the male thread 15 of the strip hole outer tube 1. Then, use the strip hole alignment die to preliminarily align the first strip hole 11 with the second strip hole 22; realize the positioning in the axial direction and the circumferential direction; The strip hole alignment die here is in a stepped shape. The outer contour of the first step is the same as that of the second strip hole 22 on the strip inner tube 2, and a large clearance fit is achieved. The outer contour of the second step is the same as that of the first strip hole 11 on the strip outer tube 1, and a large clearance fit is achieved, which is convenient for insertion to realize the preliminary alignment of the first strip hole 11 and the second strip hole 22; S2. Place a female end coaxial positioning ring between the female end round tube 24 and the female thread 14, and place a male end coaxial positioning ring between the male end round tube 25 and the male thread 15, so as to adjust the radial positions of the female end round tube 24 and the male end round tube 25 to make them coaxial with the female thread 14 and the male thread 15 respectively, that is, coaxial with the inner holes at both ends of the strip hole outer tube 1 processed by one-time positioning and clamping of the female thread and the male thread, and realize the coaxial positioning in the radial direction; The female end coaxial positioning ring is an annular workpiece with a thickness of 10 mm. The inner diameter can have a small clearance fit with the outer diameter of the female end round tube 24 at one end of the strip hole inner tube 2, and the outer diameter can have a small clearance fit with the inner diameter of the flange at the end of the female thread 14 of the strip hole outer tube 1; the male end coaxial positioning ring is also an annular workpiece with a thickness of 10 mm. The inner diameter can have a small clearance fit with the outer diameter of the male end round tube 25 at one end of the strip hole inner tube 2, and the outer diameter can have a small clearance fit with the inner diameter at one end of the male thread 15 of the strip hole outer tube 1.

[0036] S3. Drill the second positioning hole 23 with the first positioning hole 12 as the reference (that is: first position and drill on the outer wall of the strip hole outer tube 1, and then drill through the strip hole outer tube 1 and the strip hole inner tube 2 at one time, simultaneously forming the first positioning hole 12 and the second positioning hole 23), and anchor the bearing positioning pin 7 (it is not taken out after processing), so that the strip hole inner tube 2 and the strip hole outer tube 1 are fastened to each other, and then remove the strip hole alignment die; S4. Use the first strip hole 11 as the welding torch inlet, seal and weld the contact seam between the first strip hole 11 and the second strip hole 22, and then correct and grind the weld seam; S5. Heat-treat the semi-finished drill pipe after sealed welding to eliminate internal stress, and remove the female end coaxial positioning ring and male end coaxial positioning ring for coaxial positioning. S6. Install the special-shaped sealing ring 21 and the screw thread sealing ring 16, and conduct batch pressure testing on the heat-treated semi-finished drill pipe. For the semi-finished drill pipe that fails to meet the sealing pressure resistance standard, repair welding treatment needs to be carried out until the pressure resistance reaches the standard. The products that cannot be repaired by welding shall be scrapped. S7. For the semi-finished drill pipe that meets the pressure resistance requirements, install the slag inlet plate 3 into the first strip-shaped hole 11 and fix it by spot welding after insertion. The inner width of the slag inlet plate 3 is equal to the width of the second strip-shaped hole 22 on the strip hole inner tube 2. After insertion and buckling, the stepped hole can be eliminated to avoid slag accumulation.

[0037] In this embodiment, by adopting weld sealing, not only the sealing problem between the radial slag inlet channel and the axial fluid supply channel is solved, but also the overall strength of the drill pipe is improved. The detachable and reusable positioning tooling makes the plug-in sealing between the inner tubes of the drill pipe more reliable.

[0038] Embodiment 2 The welded shield pressure relief drill pipe in outburst coal seams described in the present invention, as Figure 7 (b), (c), (d) shown, has various appearance implementation modes (as shown in 7a in the figure, which is the technical solution in Embodiment 1). Specifically, as Figure 7 (b) shown, a plurality of spiral grooves 13 and axial grooves 17 are circumferentially arranged on the outer edge of the strip hole outer tube 1A, and slag inlet round holes are arranged at the intersection of the spiral grooves 13 and the axial grooves 17. At the same time, the supporting slag inlet plate 3 is changed from a long strip shape to a circular shape. As Figure 7 (c) shown, a plurality of spiral grooves 13 and axial grooves 17 are circumferentially arranged on the outer edge of the strip hole outer tube 1B, and slag inlet round holes are arranged at the intersection of the spiral grooves 13 and the axial grooves 17. At the same time, the supporting slag inlet plate 3A is a long strip plate (see Figure 9 ), and the size and layout of the slag inlet holes 31 are the same on the slag inlet plate 3 and the slag inlet plate 3A. On the slag inlet plate 3, a number of protrusions 32 are arranged on the surface where the small mouth of the slag inlet hole 31 is located for slag crushing. The protrusions 32 and the slag inlet holes 31 are arranged alternately to ensure that a number of slag inlet holes 31 on the slag inlet plate 3A coincide with the circular slag inlet channels arranged on the strip hole outer tube 1B. In order to avoid the occurrence of stepped holes at the weld and slag accumulation, first install an annular bushing 18 in the circular slag inlet channel of the strip hole outer tube 1B (see Figure 8 b), and then the slag inlet plate 3A is inserted, buckled and fixed by spot welding. As Figure 7As shown in Fig. (d), a plurality of spiral grooves 13 are circumferentially arranged on the outer edge of the strip-hole outer tube 1C (axial grooves 17 are no longer arranged), the slag inlet round holes replace the first strip hole 11 and are arranged along the spiral grooves 13. Similarly, the slag inlet round holes are spirally arranged corresponding to the spiral ribs on the strip-hole inner tube. The flow supply channel 4 here is spiral. In the above embodiments, except for the mentioned changes, other structures are the same as those in Embodiment 1.

[0039] As Figure 8 shown, the cross-sectional view of the protruding coal seam welded shielded pressure relief drill pipe has various assembly combination forms. Specifically, as Figure 8 (a) shown, the inner surface of the strip-hole outer tube 1 is circular, the outer edges of the three ribs of the strip-hole inner tube 2 are arc surfaces, and the cross-section at the contact position between the strip-hole outer tube 1 and the strip-hole inner tube 2 is an arc surface structure; as Figure 8 (b) shown, the inner surface of the strip-hole outer tube 1A is a combination of an arc and a plane, the outer edges of the three ribs of the strip-hole inner tube 2A are planes, and the cross-section at the contact position between the strip-hole outer tube 1 and the strip-hole inner tube 2A is a plane structure. When the strip-hole outer tube 1A bears torque, in addition to the welded connection, this structure itself can make the strip-hole inner tube 2A assist in bearing a certain torque, improving the overall torsional resistance; as Figure 8 (c) shown, the inner surface of the strip-hole outer tube 1C is circular, the protruding ribs of the strip-hole inner tube 2B are spiral structures, and the cross-section at the contact position between the strip-hole outer tube 1C and the strip-hole inner tube 2B is an arc surface structure; as Figure 8 (d) shown, in another embodiment of the strip-hole outer tube 1, the inner surface is a triangular-like structure, the outer edges of the three ribs of the strip-hole inner tube 2C are planes, and the cross-section at the contact position between the strip-hole outer tube 1 and the strip-hole inner tube 2C is a plane structure. When the strip-hole outer tube 1 bears torque, in addition to the welded connection, this structure itself can make the strip-hole inner tube 2C assist in bearing a certain torque, improving the overall torsional resistance; as Figure 8 (e) shown, in the third embodiment of the strip-hole outer tube 1, the inner surface is a triangular-like structure and arc grooves are arranged on the right-angled sides. The outer edges of the three ribs of the strip-hole inner tube 2D are a combination of a plane and an arc surface. The inner hole surface of the strip-hole outer tube 1 and the outer edge of the strip-hole inner tube 2D can be fitted and assembled. Similarly, when the strip-hole outer tube 1 bears torque, in addition to the welded connection, this structure itself can make the strip-hole inner tube 2D assist in bearing a larger torque, improving the overall torsional resistance; as Figure 8 (f) shown, in the fourth embodiment of the strip-hole outer tube 1, three axial protrusions are circumferentially and evenly distributed on the inner surface, the thickness at other positions is relatively thinner, and the first strip hole 11 or round hole is arranged along the axial protrusions, achieving a reduction in weight while maintaining the structural strength. The outer edges of the three ribs of the strip-hole inner tube 2C are planes, and the inner hole protrusions of the strip-hole outer tube 1 are in one-to-one butt joint and fit with the three ribs of the strip-hole inner tube 2C. When the strip-hole outer tube 1 bears torque, in addition to the welded connection, this structure has the ability to improve the overall torsional resistance of the strip-hole outer tube 1; as Figure 8As shown in (g), another embodiment of the strip-hole outer tube 1A is that two axial protrusions are circumferentially distributed on the inner surface, and the thickness at other positions is relatively thinned. Moreover, the first strip hole 11 or circular hole is arranged along the axial protrusion. The strip-hole inner tube 2E is a common circular tube. The two ribs protruding from the inner hole of the strip-hole outer tube 1A are correspondingly fitted with the circular holes arranged on the strip-hole inner tube 2E, and are welded and sealed to isolate the corresponding flow channels and slag discharge channels.

[0040] The above embodiments do not impose any formal restrictions on the shape, material, structure, etc. of the present invention. Any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention all fall within the protection scope of the technical solution of the present invention.

[0041] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation on the protected content of the present invention.

[0042] If terms such as "first" and "second" are used in this article to limit components, those skilled in the art should be aware that the use of "first" and "second" is only for the convenience of describing the present invention and simplifying the description. Without additional declaration, the above terms have no special meaning.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A welded shield pressure relief drill pipe for a protruding coal seam, comprising a strip hole outer pipe (1), characterized in that: A stripe-hole inner tube (2) is arranged inside the stripe-hole outer tube (1), and a slag inlet plate (3) is arranged on the circumferential wall of the stripe-hole outer tube (1); An axial flow channel (4) for flowing in the direction of the drill bit is formed between the inner wall of the strip hole outer tube (1) and the outer wall of the strip hole inner tube (2); a slag discharge channel (5) having a flow direction opposite to that of the axial flow channel (4) and isolated from each other is formed in the central hole of the strip hole inner tube (2); a through slag feed hole (31) is formed on the slag feed plate (3); and a slag feed channel (6) connecting the slag feed hole (31) and the slag discharge channel (5) is formed in the radial direction of the circumferential walls of the strip hole outer tube (1) and the strip hole inner tube (2).

2. The welded shield pressure relief drill pipe for protruding coal seams according to claim 1 is characterized in that: The outer surface of the strip hole outer tube (1) is provided with a spiral groove (13) and an axial groove (17); both ends of the strip hole outer tube (1) are provided with a female buckle (14) and a male buckle (15) that can be connected to the female buckle (14) of another strip hole outer tube (1); and a threaded sealing ring (16) is provided at the root of the female buckle (14).

3. The welded shield pressure relief drill pipe for protruding coal seams according to claim 1 is characterized in that: The two ends of the strip hole inner tube (2) are respectively processed into a female end circular tube (24) and a male end circular tube (25) that can be connected to the female end circular tube (24) of another strip hole inner tube (2), and a special-shaped sealing ring (21) is provided on the female end circular tube (24).

4. The welded shield pressure relief drill pipe for protruding coal seams according to claim 1 is characterized in that: The inner hole of the strip hole outer tube (1) may be circular, polygonal or other special shapes.

5. The welded shield pressure relief drill pipe for protruding coal seam according to claim 1 is characterized in that: The strip hole outer tube (1) is provided with at least two first strip holes (11) or first slag inlet circular holes, the strip hole inner tube (2) is provided with convex ribs, and the convex ribs are provided with second strip holes (22) corresponding one-to-one to the first strip holes (11) or second slag inlet circular holes corresponding one-to-one to the first slag inlet circular holes; The width of the second strip-shaped hole (22) is smaller than the width of the first strip-shaped hole (11), and the length of the second strip-shaped hole (22) is smaller than the length of the first strip-shaped hole (11); The diameter of the second slag inlet circular hole is smaller than the diameter of the first slag inlet circular hole.

6. The welded shield pressure relief drill pipe for protruding coal seams according to claim 5 is characterized in that: At least one first positioning hole (12) is formed on the perforated outer tube (1), and second positioning holes (23) corresponding one to one with the first positioning holes (12) are formed on the convex rib.

7. The welded shield pressure relief drill pipe for protruding coal seams according to claim 6 is characterized in that: The slag inlet plate (3) is installed in the first strip hole (11); the slag inlet hole (31) is a tapered hole, and the opening of the larger side of the tapered hole faces the center of the strip hole outer tube (1).

8. A sealing assembly method for a welded shield pressure relief drill pipe for a protruding coal seam, based on the welded shield pressure relief drill pipe for a protruding coal seam according to claim 7, characterized in that: The following steps are involved: S1, inserting the strip hole inner tube (2) into the inner cavity of the strip hole outer tube (1), with the female end round tube (24) located on one side of the female buckle (14), and then using a strip hole alignment die to preliminarily align the first strip hole (11) with the second strip hole (22), and aligning the end surface of the male end round tube (25) with the end surface of one side of the male buckle (15) of the strip hole outer tube (1); S2, inserting a female coaxial positioning ring between the female round tube (24) and the female buckle (14), and inserting a male coaxial positioning ring between the male round tube (25) and the male buckle (15), thereby adjusting the radial positions of the female round tube (24) and the male round tube (25) so that they are coaxial with the female buckle (14) and the male buckle (15), respectively; S3, drilling a second positioning hole (23) based on the first positioning hole (12), and anchoring a load-bearing positioning pin (7) to fasten the inner tube (2) and the outer tube (1) to each other, and then removing the alignment die for the strip holes; S4, using the first strip hole (11) as an inlet for a welding gun, performing sealing welding on the contact seam between the first strip hole (11) and the second strip hole (22); S5. Heat-treating the semi-finished drill pipe after sealing welding to eliminate internal stress, and removing the female end coaxial positioning ring and the male end coaxial positioning ring used for coaxial positioning; S6, installing the special-shaped sealing ring (21) and the threaded sealing ring (16), and performing batch pressure testing on the semi-finished drill pipes after heat treatment; S7. For the semi-finished drill pipe that meets the pressure resistance requirements, install the slag feed plate (3) into the first strip hole (11).

9. The sealing assembly method of the welded shield pressure relief drill pipe for the protruding coal seam according to claim 8 is characterized in that: The slag inlet plate (3) and the strip hole outer tube (1) in the S7 are fixed by spot welding after insertion.

10. The sealing assembly method of the welded shield pressure relief drill pipe for the protruding coal seam according to claim 8, characterized in that: The semi-finished drill pipe in S6 that does not meet the sealing and pressure resistance standards needs to be repaired by welding until the pressure resistance standards are met.

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