Direct discharge pipeline welding device

Abstract

The invention belongs to the technical field of coal mine underground pipeline welding, and particularly relates to a direct discharge pipeline welding device which comprises a pair of lower trays, a pair of upper cover discs and an injection unit. The lower tray can be fixedly buckled into a circular ring body, the upper cover disc can be fixedly buckled into a fan-shaped body, and a vertically-through hole channel is formed between the circular ring body and the fan-shaped body. A column casing is arranged on the lower tray, a guide rod is arranged on the upper cover disc, and the column casing and the guide rod can be selectively switched between a fixed matching state and a movable matching state. The spraying unit is fixedly matched with the lower tray and comprises a plurality of nozzles which are arranged on the lower tray in a pivoted mode and arranged on the semi-circumference at intervals, and spraying openings of the nozzles can turn over in the radial direction. And an inclined surface part corresponding to the upper part of the nozzle is formed on the upper cover disc. Dust attached to the pipe wall of the straight pipe can be cleaned, the concentration of combustible gas near the welding position is fully reduced, the quality of butt welding seams between the straight pipes can be improved, and the safety of welding operation can be improved.

Description

Technical Field

[0001] This invention belongs to the field of underground pipeline welding technology in coal mines, and specifically relates to a straight-line pipeline welding device. Background Technology

[0002] In underground coal mine operations, the underground pump room plays a crucial role in drainage, and the stable operation of its direct discharge pipeline is directly related to the safe production of the mine. However, the environment of the underground pump room is extremely complex, with air humidity often exceeding 80%, and the air filled with large amounts of dust and flammable and explosive gases such as methane. Dust easily adheres to the welding area of ​​the straight pipe, causing welding defects. Flammable and explosive gases such as methane affect the safety of straight pipe welding operations, requiring extremely high welding skills.

[0003] A portable semi-automatic welding device, commonly used in welding operations of straight pipes in pump room wells, improves welding efficiency compared to conventional welding devices. However, because this portable semi-automatic welding device lacks specific mechanisms to address the high dust and flammable / explosive gas environments in pump rooms, dust adhering to the pipe walls and flammable / explosive gases in the air remain the main factors restricting further improvements in welding quality and efficiency when using it for welding straight pipes in underground pump rooms. Furthermore, significant safety hazards remain. Summary of the Invention

[0004] To overcome the adverse effects of dust adhering to the walls of straight pipes on welding operations, this invention provides a straight-pipe welding device that can clean the dust adhering to the walls of straight pipes and sufficiently reduce the concentration of combustible gases near the welding position, thereby helping to improve the quality of butt welds between straight pipes and enhance the safety of welding operations.

[0005] The technical solution adopted by this invention to solve its technical problem is: a straight-line pipe welding device, comprising a pair of lower trays, a pair of upper cover plates, and a spraying unit. The two lower trays can be fixedly fastened into a ring. The two upper cover plates can be fixedly fastened into a sector shape, and a central hole is formed at the center of the sector shape, communicating vertically with the axial hole of the ring formed by the two upper trays. Multiple vertically upward-extending cylindrical columns are provided on the lower trays. Multiple vertically downward-extending guide rods are provided on the upper cover plates, each corresponding to one of the cylindrical columns, allowing the guide rods to pass through the cylindrical columns and extend below the lower end face of the lower trays.

[0006] The upper part of the cylinder has an external threaded section, and the end of the external threaded section is formed into an external conical surface. Multiple axial grooves are formed on the upper part of the external threaded section, distributed alternately around the circumference. A threaded sleeve is disposed on the external threaded section, and a tapered hole is formed on the upper part of the inner wall of the threaded sleeve. When the threaded sleeve is screwed on to move up and down relative to the external threaded section, the tapered hole can match the external conical surface, allowing the cylinder / lower tray and guide rod / upper cover plate to selectively switch between a fixed matching state and a movable matching state, thereby achieving adjustment of the vertical distance between the lower tray and the upper cover plate.

[0007] The injection unit is fixedly matched with the lower tray and includes multiple nozzles pivotally mounted on the inner bottom surface of the lower tray and arranged alternately on a semicircle. The nozzle orifices can be flipped radially, maintaining either an outward-facing or inward-facing position. An inclined surface is formed on the upper cover plate, corresponding to the multiple nozzles. The airflow ejected from the nozzles is directed outwards onto the inclined surface and is deflected by the inclined surface to the axis of the annular body formed by the two lower trays.

[0008] Optionally, the two lower trays are respectively provided with half-cylinder one and half-cylinder two, and when the two lower trays are fixedly fastened into a ring, the cylindrical cavity formed by half-cylinder one and half-cylinder two can communicate with the shaft hole of the ring in the vertical direction. Half-cylinder one and half-cylinder two are fixedly connected in a detachable manner by multiple stud assemblies.

[0009] Optionally, the lower tray is a separate structure from the first and second semi-cylinders. Both the outer walls of the first and second semi-cylinders have radially extending flanges. Multiple screws are mounted on each flange, and a threaded ring and a spring are fitted onto the section of each screw extending above the flange. The lower end face of the lower tray has threaded countersunk holes that correspond one-to-one with the screws. The two ends of the spring contact the upper end face of the threaded ring and the lower end face of the lower tray, respectively.

[0010] Optionally, multiple magnetic blocks are distributed on the opposite end faces between the two lower trays, and the magnetic blocks on the end faces of the two lower trays can attract each other, thereby holding the two lower trays together by magnetic attraction and keeping them in a snap-fit ​​state as a ring.

[0011] Optionally, the two upper cover plates are respectively provided with half-cylinder three and half-cylinder four, and when the two upper cover plates are fixedly fastened into a fan shape, the cavity formed by the fastening of half-cylinder three and half-cylinder four is vertically connected to the central hole of the fan shape. Half-cylinder three and half-cylinder four are detachably fixedly connected by multiple stud assemblies.

[0012] Optionally, an axial flange is formed at the edge on the upper end surface of the lower tray, and when the two lower trays are fastened together, the axial flanges formed on the two lower trays can be engaged to form an annular flange body. The cylinders all extend upward from the upper end surface of the axial flange.

[0013] Optionally, an arc-shaped groove is formed on the upper surface of the lower tray near the axis, and when the two lower trays are fastened together, the arc-shaped grooves formed on the two lower trays can be matched to form an annular groove.

[0014] Optionally, an axial flange is formed on the lower end face of the upper cover plate at the edge of the circumferential side, and after the two upper cover plates are fastened together, the axial flanges formed on the two upper cover plates can be engaged to form a semi-circular flange body. The guide rods all extend downward from the lower end face of the flange body.

[0015] The beneficial effects of this invention are: it can clean the dust adhering to the wall of straight pipes and significantly reduce the concentration of combustible gases near the welding position, which helps to improve the quality of butt welds between straight pipes and improve the safety of welding operations. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a partial cross-sectional structure in the main view of this application.

[0017] Figure 2 for Figure 1 A magnified schematic diagram of the structure at point A in the middle.

[0018] Figure 3 This is a top view of the lower tray in its assembled state.

[0019] Figure 4 This is a schematic diagram of the upper cover plate in its assembled state, viewed from below.

[0020] Figure 5 This is a schematic diagram of the lower tray in its split state, viewed from below.

[0021] Figure 6 This is a top view of the upper cover plate in its split state.

[0022] In the diagram: 100 Straight Pipe 1, 200 Straight Pipe 2, 300 Weld Seam; 10 Lower Tray, 11 Half-Cylinder 1, 111 Half-Cylinder 2, 1111 Stud 1, 1112 Nut 1, 112 Protruding Column 1, 113 Through Hole 1, 12 Column, 121 External Thread Section, 1211 External Thread Surface, 1212 Axial Groove, 1213 External Conical Surface, 13 Threaded Sleeve, 131 Conical Hole, 14 Annular Groove, 15 Inner Bottom Surface, 16 Magnetic Block; 20 Upper Cover Plate, 21 Half-Cylinder 3, 211 Half-Cylinder 4, 2111 Stud 2, 2112 Nut 2, 212 Protruding Column 2, 213 Through Hole 2, 22 Guide Rod, 23 Inclined Section; 30 Spray Unit, 31 Nozzle; 1 Edge Plate, 2 Screw, 3 Threaded Ring, 4 Spring Component, 5 Axial Protruding Column. Detailed Implementation

[0023] The structures, proportions, and sizes depicted in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or objectives of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, terms such as "upper," "lower," "front," "rear," and "middle" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0024] like Figures 1 to 6 The diagram shows a straight-line pipe welding device, comprising a pair of lower trays 10, a pair of upper cover plates 20, and a spraying unit 30. The lower trays 10 are semi-circular, and the two lower trays 10 can be fixedly fastened into a ring. The upper cover plates 20 are fan-shaped with a central angle approximately (close to) a right angle (the included central angle can be between 90 and 120 degrees), and the two upper cover plates 20 can be fixedly fastened into a roughly semi-circular fan-shaped body. A central hole is formed at the center of the fan-shaped body formed by the fastening of the two upper cover plates 20, communicating vertically with the axial hole of the ring formed by the fastening of the two upper trays 10. See... Figure 1 As shown, straight pipe 100 and straight pipe 200, which are welded together, pass through the shaft hole and the central hole of the annular body, respectively, and are joined together. Therefore, the inner diameters of the shaft hole and the central hole of the annular body are consistent with the outer diameters of the straight pipes (straight pipe 100 and straight pipe 200). The two lower trays 10, when fixedly fastened together, can clamp the straight pipe 100, and the two upper cover plates 20, when fixedly fastened together, can clamp the straight pipe 200. This ensures that the weld seam 300 between the butt joints of the two straight pipes corresponds to the vertical distance between the lower tray 10 and the upper cover plate 20.

[0025] The lower tray 10 is provided with a plurality of vertically upward extending cylinders 12. The upper cover plate 20 is provided with a plurality of vertically downward extending guide rods 22 that correspond one-to-one with the cylinders 12, and the guide rods 22 can all pass through the cylinder cavity of the cylinder 12 and extend to below the lower end face of the lower tray 10. After the cylinders 12 and the guide rods 22 are inserted and matched, the lower tray 10 and the upper cover plate 20 on the front side, and the lower tray 10 and the upper cover plate 20 on the rear side can move up and down relative to each other. Thus, after the two lower trays 10 are fixedly fastened together, and after the two upper cover plates 20 are fixedly fastened together, the annular body (formed by the fixed fastening of the two lower trays 10) can move up and down relative to the sector body (formed by the fixed fastening of the two upper cover plates 20).

[0026] An axial flange is formed at the edge on the upper end surface of the lower tray 10, and when the two lower trays 10 are fastened together, the axial flanges formed on the two lower trays 10 can be engaged to form an annular flange body. The column cylinders 12 all extend upward from the upper end surface of the axial flange.

[0027] An axial flange is formed on the lower end surface of the upper cover plate 20 at the edge of the circumferential side. When the two upper cover plates 20 are fastened together, the axial flanges formed on the two upper cover plates 20 can be engaged to form a semi-circular flange body. The guide rods 22 all extend downward from the lower end surface of the flange body.

[0028] like Figure 1 , Figure 2 As shown, the upper part of the cylinder 12 has an external thread section 121, and the end of the external thread section 121 is formed as an external conical surface 1213 (with the small diameter end being a free end). The upper part of the external thread section 121 has a plurality of axial grooves 1212 distributed alternately around the circumference. A threaded sleeve 13 is disposed on the external thread section 121, and a tapered hole 131 is formed at the upper end of the inner wall of the threaded sleeve 13. The lower part of the inner wall of the threaded sleeve 13 has an internal thread section that matches the external thread surface 1211 on the external thread section 121.

[0029] When the threaded sleeve 13 is screwed on and moved up and down relative to the external thread section 121, the tapered hole 131 can match the external tapered surface 1213, thereby tightening and loosening the inner diameter of the upper port of the column cylinder 12. This allows the column cylinder 12 / the lower tray 10 and the guide rod 22 / the upper cover plate 20 to selectively switch between a fixed matching state and a movable matching state, thereby realizing the adjustment of the vertical distance / position between the lower tray 10 and the upper cover plate 20.

[0030] The injection unit 30 is fixedly matched with the lower tray 10. The injection unit 30 includes four nozzles 31 pivotally mounted on the inner bottom surface 15 of the lower tray 10 and arranged alternately on a semicircle, such that the injection orifices of the nozzles 31 can all be flipped in the radial direction to eject an outwardly inclined airflow (see...). Figure 1 And the inwardly inclined airflow (at which time the jet airflows of multiple nozzles 31 can converge in the direction of the axis extension of the straight pipe).

[0031] The upper cover plate 20 has beveled surfaces 23 that correspond to the nozzles 31. The airflow ejected from the nozzles 31 is directed outwards onto the beveled surfaces 23, and is deflected / reflected by the beveled surfaces 23 towards the axis (i.e., the inner side) of the annulus formed by the two lower trays 10. (See [reference]) Figure 1 The dashed arrows shown indicate the path.

[0032] The inclined portion 23 extends obliquely from the root of the flange towards the axis. An arc-shaped groove is formed on the upper end surface of the lower tray 10 near the axis, and when the two lower trays 10 are fastened together, the arc-shaped grooves formed on the two lower trays 10 can be matched to form an annular groove 14. The nozzles 31 are distributed around the annular groove 14.

[0033] After the two lower trays 10 are fastened together, by adjusting the tightness between them and the straight tube 100, the lower tray 10 can rotate relative to the straight tube 100 and remain relatively fixed in the axial direction; similarly, after the two upper cover plates 20 are fastened together, by adjusting the tightness between them and the straight tube 200, the upper cover plate 20 can rotate relative to the straight tube 200 and remain relatively fixed in the axial direction.

[0034] When the nozzle 31 is oriented outward, the vertical distance between the lower tray 10 and the upper cover plate 20 can be controlled to adjust the position of the airflow ejected from the nozzle 31 acting on the inclined surface 23. This allows for the control of the path of the airflow being deflected by the inclined surface 23, thus adjusting the vertical height of the airflow acting on the straight pipe. This enables the airflow to sweep the area near the weld seam 300, reducing and controlling the concentration of combustible gas near the weld seam 300.

[0035] When the nozzle 31 is oriented inward, the vertical distance between the lower tray 10 and the upper cover plate 20 can be controlled to control the position of the airflow ejected by the multiple nozzles 31 acting on the outer wall of the straight pipe, thereby cleaning the dust at the upper and lower positions of the weld seam 300.

[0036] The injection unit 30 also includes a flow pump, a booster pump, and a controller. The controller can adjust the operating status of the flow pump and the booster pump to control the airflow and jet intensity, thereby adapting to the dust cleaning intensity requirements and controlling the concentration of combustible gases. The specific mechanical structure and control circuit structure of the injection unit 30 can be implemented by those skilled in the art based on the technical objectives of this application and with reference to existing technologies. Since it is only an auxiliary part of the technical solution of this application, it will not be described in detail or limited further.

[0037] like Figures 1 to 6The two lower trays 10 are respectively provided with a first half-cylinder 11 and a second half-cylinder 111. When the two lower trays 10 are fixedly fastened into a ring, the cylindrical cavity formed by the first half-cylinder 111 and the second half-cylinder 111 communicates vertically with the shaft hole of the ring. The first half-cylinder 111 and the second half-cylinder 111 are fixedly connected by a plurality of stud assemblies. The stud assembly may include a stud body 1111 and a nut 1112, and correspondingly, a plurality of protruding protrusions 112 and through holes 113 passing through the protruding protrusions 112 are formed on the first half-cylinder 111. The stud body 1111 passes through the through hole 113 in the front-rear direction and extends from the free end / rear end of the protruding protrusion 112 to match the nut 1112.

[0038] The stud body 1111 is integrally formed with the semi-cylinder 111 and can pass through the through hole 113 to match the nut 1112. Tightening the nut 1112 can fix the semi-cylinder 111 and the semi-cylinder 111 together. It should be noted that when the two lower trays 10 and the two semi-cylinders (i.e., the semi-cylinder 11 and the semi-cylinder 111) are integrally formed, by distributing the number and axial distribution of the aforementioned stud assemblies, it is generally sufficient to fix the two lower trays 10 together simultaneously. See [reference needed]. Figure 1 The upper cover plate 20 shown has an engagement structure; when the two lower trays 10 and the two semi-cylinders are separate structures, multiple magnetic blocks 15 need to be distributed on the engagement end faces of the two lower trays 10, and the magnetic blocks 15 on the two lower trays 10 can be attracted together by magnetic force, so that the two lower trays 10 can be tightly held together with a sufficiently large holding force and are not easy to separate.

[0039] The lower tray 10 is a separate structure from the first half-cylinder 11 and the second half-cylinder 111, and is fixedly connected to the lower tray 10 and the half-cylinders by multiple screws 2. Specifically, radially extending flanges 1 are formed on the outer walls of the first half-cylinder 11 and the second half-cylinder 111. Multiple screws 2 are arranged on the flanges 1, and a threaded ring 3 and a spring 4 are sleeved on the section of the screw 2 extending above the flange 1. Multiple axial protrusions 5 are provided on the lower end face of the lower tray 10, and threaded countersunk holes corresponding to the screws 2 are formed on the axial protrusions 5. The two ends of the spring 4 are in contact with the upper end face of the threaded ring 3 and the lower end face of the lower tray 10, respectively. Tightening the threaded ring 3 can adjust the extension and retraction state of the spring 4, thereby controlling the elastic thrust acting on the lower tray 10.

[0040] By designing the lower tray 10, the first half-cylinder 11, and the second half-cylinder 111 as separate structures, the lower tray 10 and the upper cover plate 20, which are connected together, can move vertically relative to the straight pipe (within the extension space of the spring member 4). This allows for convenient control of the airflow acting on the position range above and below the weld seam 300 within the vertical space range of movement, making it easier to complete the dust cleaning operation on the straight pipe wall.

[0041] Two upper cover plates 20 are respectively provided with a third half-cylinder 21 and a fourth half-cylinder 211. When the two upper cover plates 20 are fixedly fastened into a fan-shaped body, the cylindrical cavity formed by the third half-cylinder 21 and the fourth half-cylinder 211 is vertically connected to the central hole of the fan-shaped body. The third half-cylinder 21 and the fourth half-cylinder 211 are detachably connected by multiple stud assemblies. The aforementioned stud assembly may include a stud body 2111 and a nut 2112, and correspondingly, multiple protruding ...

[0042] The stud body 2111 is integrally formed with the semi-cylinder 211 and can pass through the through hole 213 to match the nut 2112. Tightening the nut 2112 can fix the semi-cylinder 21 and the semi-cylinder 211 together.

[0043] In the technical solution of this application, two lower trays 10 that can be selectively fastened into annular bodies and two upper cover plates 20 that can be selectively fastened into fan-shaped bodies are provided to support the first straight pipe 100 and the second straight pipe 200 respectively. This achieves the purpose of constraining the axial alignment (position) of the two straight pipes and controlling the position of the weld seam 300 at the joint end of the two straight pipes between the lower trays 10 and the upper cover plates 20. At the same time, the vertical distance between the lower trays 10 and the upper cover plates 20 can be adjusted, and the spray direction of the nozzles 31 provided on the lower trays 10 can be controlled (spraying upwards to the outside and spraying upwards to the inside), and interacts with the inclined surface 23 to achieve the purpose of cleaning dust on the pipe wall and controlling the concentration of combustible gas in the space near the weld seam 300, thereby improving the quality of the weld seam 300 and operational safety. In particular, by configuring the lower tray 10 with the first half-cylinder 11 and the second half-cylinder 111 as separate structures and connecting them with screws 2, springs 4, etc., it is only necessary to loosen the tightness of the upper cover plate 20 and the second straight tube 200, and apply pressure only to the lower tray 10 to make the lower tray 10 float up and down relative to the first straight tube 100 in the vertical direction. In operation, it is easier to control the airflow acting on the floating space above and below the weld seam 300 and to rotate relative to the straight tube at the same time, making the dust cleaning operation on the (straight tube) wall more convenient, faster and less labor-intensive.

[0044] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Many aspects of the present invention can be improved without departing from the overall concept. Those skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A straight pipe welding apparatus characterized by comprising: It comprises a pair of lower trays (10), a pair of upper cover plates (20), and a spraying unit (30); The two lower trays (10) can be fixedly buckled into a circular body; the two upper cover plates (20) can be fixedly buckled into a fan-shaped body, and an axial hole is formed in the center of the fan-shaped body and can pass through the axial hole of the circular body vertically; a plurality of cylindrical columns (12) vertically upwardly extending are arranged on the lower tray (10); a plurality of guide rods (22) vertically downwardly extending and corresponding to the cylindrical columns (12) are arranged on the upper cover plate (20); the guide rods (22) can pass through the cylindrical columns (12) and extend below the lower end surface of the lower tray (10). The upper part of the cylindrical column (12) is formed with an external thread segment (121) with an outer conical surface (1213); the upper part of the external thread segment (121) is formed with a plurality of axial grooves (1212) distributed around the circumference; a threaded sleeve (13) is arranged on the external thread segment (121), and a tapered hole (131) is formed on the inner wall of the threaded sleeve (13); when the threaded sleeve (13) is screwed to move up and down relative to the external thread segment (121), the tapered hole (131) can match the outer conical surface (1213), so that the cylindrical column (12) and the guide rod (22) can be switched between the fixed matching state and the movable matching state. The spraying unit (30) is fixedly matched with the lower tray (10) and comprises a plurality of nozzles (31) pivotally arranged on the inner bottom surface (15) of the lower tray (10) and arranged on half of the circumference, so that the spray port of the nozzle (31) can be turned in the radial direction; the upper cover plate (20) is formed with a bevel part (23) corresponding to the upper part of the nozzle (31); the airflow sprayed by the nozzle (31) can be obliquely sprayed on the bevel part (23) and can be deflected to the axial line side of the circular body by the bevel part (23).

2. A straight tube welding apparatus according to claim 1, characterized in that: Half cylinder one (11) and half cylinder two (111) are respectively arranged on the two lower trays (10), and when the two lower trays (10) are fixedly buckled into a circular body, the cylinder cavity formed by the buckling of the half cylinder one (11) and the half cylinder two (111) is vertically through the axial hole of the circular body; the half cylinder one (11) and the half cylinder two (111) are fixedly connected in a detachable manner by a plurality of stud assemblies.

3. A straight tube welding apparatus according to claim 2, wherein: The lower tray (10), the half cylinder one (11), and the half cylinder two (111) are in a split structure; the outer wall of the half cylinder one (11) and the outer wall of the half cylinder two (111) are both formed with a rim plate (1) extending in the radial direction; a plurality of screw rods (2) are arranged on the rim plate (1), and a screw ring (3) and a spring member (4) are arranged on the part of the screw rod (2) extending above the rim plate (1); a threaded counterbore corresponding to the screw rod (2) is arranged on the lower end surface of the lower tray (10); the two ends of the spring member (4) are in contact with the upper end surface of the screw ring (3) and the lower end surface of the lower tray (10), respectively.

4. A straight tube welding apparatus according to claim 3, wherein: A plurality of magnetic force blocks (16) are arranged on the opposite end surfaces between the two lower trays (10), and the magnetic force blocks (16) arranged on the two lower trays (10) can be attracted to each other.

5. A straight tube welding apparatus according to any one of claims 1 to 4, characterized in that: Two upper cover discs (20) are respectively provided with half cylinder three (21) and half cylinder four (211), and when the two upper cover discs (20) are fixed and buckled into a sector body, the cylinder cavity buckled by the half cylinder three (21) and the half cylinder four (211) is through the axial hole of the sector body in the vertical direction; the half cylinder three (21) and the half cylinder four (211) are fixedly connected in a detachable manner through a plurality of stud assemblies.

6. A straight tube welding apparatus as defined in claim 1, wherein: An axial flange is formed on the upper end surface of the lower tray (10) at the edge, and after the two lower trays (10) are buckled together, the axial flanges formed on the two lower trays (10) can be closed into an annular flange body; the cylinder (12) extends upward from the upper end surface of the axial flange.

7. A straight tube welding apparatus as defined in claim 1, wherein: An arc-shaped groove is formed on the upper end surface of the lower tray (10) at the position close to the axial line, and after the two lower trays (10) are buckled together, the arc-shaped grooves formed on the two lower trays (10) can be closed into an annular groove (14).

8. A straight tube welding apparatus as defined in claim 1, wherein: An axial flange is formed on the lower end surface of the upper cover disc (20) at the edge of the peripheral surface side, and after the two upper cover discs (20) are buckled together, the axial flanges formed on the two upper cover discs (20) can be closed into a semicircular annular flange body; the guide rod (22) extends downward from the lower end surface of the flange body.

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