An end discharge device for reducing the residual of a large-diameter steel pipe inner surface modification liquid

Abstract

The present application relates to the technical field of metal pipe processing, and particularly relates to an end discharging device for reducing the residue of inner surface modification liquid of large-diameter steel pipe, which comprises a slip ring rotatably installed at the end of the steel pipe, the wall surface of the slip ring abuts against the end surface of the end of the steel pipe, a slip ring liquid outlet groove is formed in the wall surface of the slip ring for guiding the liquid in the steel pipe out, a sleeve ring is installed at the end of the steel pipe, the sleeve ring is provided with a sleeve ring liquid outlet hole, and a flow guide channel extending to the direction of the slip ring and communicating with the sleeve ring liquid outlet hole is arranged on the inner wall of the sleeve ring, wherein the slip ring liquid outlet groove and the sleeve ring liquid outlet hole are aligned by rotating the slip ring, so as to form a liquid outflow channel together with the flow guide channel.

Description

Technical Field

[0001] This invention relates to the field of metal pipe processing technology, and in particular to an end discharge device for reducing the residue of modified liquid on the inner surface of large-diameter steel pipes. Background Technology

[0002] Large-diameter stainless steel pipes are widely used in corrosive environments such as chemical, marine, and metallurgical industries due to their excellent structural performance. Traditional solutions in these applications often use nickel-based alloy pipes to meet corrosion resistance requirements, but the high cost of raw materials significantly increases construction and equipment manufacturing costs. To reduce material costs while maintaining corrosion resistance, the industry commonly employs ionic liquid surface modification technology to treat the inner surface of ordinary large-diameter stainless steel pipes. This technology forms a strong, dense, and corrosion-resistant film on the inner surface of the pipe, enabling ordinary stainless steel pipes to achieve corrosion resistance close to that of nickel-based alloys, thus significantly controlling costs. Ionic liquid, the core medium in this surface modification process, is expensive and has high viscosity at room temperature. Furthermore, its unique chemical properties mean that it volatilizes upon contact with air, producing harmful gases that not only endanger the health of on-site personnel but also cause air and soil pollution. Additionally, the ionic liquid itself deteriorates upon contact with air, rendering it unusable. Therefore, reducing the residue and loss of ionic liquid and avoiding its contact with air are key issues that urgently need to be addressed in the ionic liquid surface modification process.

[0003] In existing technologies, the recovery of ionic liquid after modification of the inner surface of steel pipes is mostly carried out by purging the pipe with high-purity gas from one end. However, this method has significant drawbacks: Firstly, the high viscosity of the ionic liquid makes it easy for liquid residue to accumulate at the bottom of long, large-diameter steel pipes, at pipe wall joints, and in dead corners of the drainage structure. High-purity gas purging is difficult to effectively clean these areas, resulting in a large waste of ionic liquid. Secondly, in order to improve the purging effect, existing technologies require a large amount of high-purity gas, which further increases the process operating cost. Moreover, the lack of an effective sealing structure during the purging process makes it easy for the ionic liquid to come into contact with air, causing the volatilization of harmful gases and deterioration of the ionic liquid. Summary of the Invention

[0004] Therefore, in view of the above problems, the present invention proposes an end discharge device for reducing the residue of modified liquid on the inner surface of large-diameter steel pipes.

[0005] This invention is achieved through the following technical solution: an end discharge device for reducing the residue of modified liquid on the inner surface of large-diameter steel pipes, comprising:

[0006] A slip ring is rotatably mounted on the end of a steel pipe. The wall of the slip ring abuts against the end face of the steel pipe. A slip ring outlet groove is provided on the wall of the slip ring for drawing out the liquid inside the steel pipe.

[0007] A collar is installed at the end of a steel pipe. The collar has a collar outlet hole, and the inner wall of the collar has a guide channel that extends toward the slip ring and communicates with the collar outlet hole.

[0008] By rotating the slip ring, the slip ring outlet groove can be aligned with the sleeve ring outlet hole, thereby forming an outlet channel for liquid to flow out together with the guide channel.

[0009] As a further improvement of the present invention, a sealing ring is provided between the slip ring and the collar, and a flow passage is provided on the sealing ring, the flow passage corresponding to the liquid outlet hole of the collar.

[0010] As a further improvement of the present invention, the collar includes a sleeve portion and a connecting portion, the sleeve portion being sleeved on the end of the steel pipe, and the connecting portion being fixedly connected to the sealing ring by a third fastener.

[0011] As a further improvement of the present invention, it also includes a mandrel inserted inside the steel pipe, the length of which is greater than the length of the steel pipe, and both ends of which protrude from the steel pipe.

[0012] The mandrel is provided with a limiting device, which is used to keep the slip ring always abutting against the end face of the steel pipe.

[0013] As a further improvement of the present invention, the limiting device includes a fixing block, which is installed on the part of the mandrel that protrudes from the steel pipe. The side wall of the fixing block is provided with a first fastener, which is inserted into the interior of the fixing block and abuts against the mandrel to achieve the positioning and fixing of the fixing block on the mandrel.

[0014] As a further improvement of the present invention, the mandrel is provided with locking ends at both ends, the diameter of the locking ends being smaller than the diameter of the mandrel body, the locking ends passing through the fixing block and being provided with at least one second fastener for locking.

[0015] As a further improvement of the present invention, a rubber ring is provided between the second bolt and the fixing block. The rubber ring is frustoconical, with its reduced-diameter end inserted into the fixing block.

[0016] As a further improvement of the present invention, it also includes a placement seat and a flipping drive mechanism. The placement seat is used to place the steel pipe, and the flipping drive mechanism is connected to the placement seat and is used to drive the placement seat to flip and tilt.

[0017] As a further improvement of the present invention, it also includes a frame, wherein the placement seat is disposed on the frame and one end of the placement seat is hinged to the frame; the flipping drive mechanism includes a telescopic cylinder disposed on the frame and the telescopic cylinder is connected to the other end of the placement seat, and the tilting of the placement seat is controlled by the telescopic cylinder.

[0018] As a further improvement of the present invention, a rotating motor is provided on the placement base, and a transmission gear is provided at the output end of the rotating motor, the transmission gear being used to drive the steel pipe to rotate.

[0019] By adopting the aforementioned technical solution, the present invention has at least the following beneficial effects:

[0020] I. This invention utilizes a rotary alignment design between the slip ring and the collar, allowing the liquid outlet holes of both the slip ring and the collar to be adjusted to the lowest point of the steel pipe's cross-section as needed. During drainage, the operator simply rotates the slip ring to align the two outlet holes, allowing the liquid inside the pipe to flow smoothly through the guide channel. This structure effectively overcomes the problem of liquid accumulation caused by differences in steel pipe wall thickness and structural dead angles, ensuring the complete drainage of viscous ionic liquid, significantly reducing ionic liquid loss, and saving on the cost of using expensive ionic liquids. Simultaneously, the adjustable outlet position design makes it easier for the liquid to flow out under gravity, reducing reliance on high-pressure gas purging, lowering high-purity gas consumption, and further reducing process operating costs.

[0021] II. This invention incorporates a sealing ring between the slip ring and the collar ring. The sealing ring has a flow-through hole corresponding to the liquid outlet hole of the collar ring, and the collar ring is fixedly connected to the sealing ring via a connecting part. This design creates a rotary seal between the sealing ring and the slip ring wall: when the slip ring rotates to the discharge position, the flow-through hole on the sealing ring communicates with the two liquid outlet holes, ensuring unobstructed discharge; when the slip ring rotates to other positions, the sealing ring blocks the channel, preventing the ionic liquid from seeping out. Ionic liquids release harmful gases upon contact with air. This sealing structure ensures that the ionic liquid does not come into contact with outside air throughout the discharge process, preventing the release of harmful gases that could harm the health of operators. It also prevents environmental pollution and deterioration of the ionic liquid, allowing the recovered ionic liquid to be reused and further reducing media loss.

[0022] III. This invention uses a mandrel penetrating a steel pipe as the installation reference. The mandrel is longer than the steel pipe, with both ends protruding from the pipe. A limiting device is provided on the mandrel, including a fixing block installed on the protruding portion of the mandrel. A first fastener on the side wall of the fixing block abuts against the mandrel for positioning, thereby supporting and limiting the slip ring, ensuring the slip ring always tightly abuts against the end face of the steel pipe. Locking ends with a diameter smaller than the main body are provided at both ends of the mandrel. After the locking ends protrude from the fixing blocks, they are locked by a second fastener to prevent axial movement of the fixing blocks. This multi-locking structure ensures precise and reliable alignment of the end device at both ends of the long steel pipe, avoiding sealing failure or misalignment of the liquid outlet due to loosening, and meeting the surface modification process requirements of large-diameter, long steel pipes.

[0023] Fourth, this invention includes a frustum-shaped rubber ring positioned between the second fastener and the fixing block, with its reduced-diameter end inserted into the fixing block. When the second fastener is tightened, the rubber ring generates a radial preload, which enhances the sealing of the locking area, preventing gas or liquid leakage from the locking end, and also acts as an anti-loosening element, preventing the fastener from loosening due to vibration. Simultaneously, the elasticity of the rubber material allows it to adapt to temperature changes during the process, maintaining a long-term stable sealing effect.

[0024] V. This invention includes a placement seat and a tilting drive mechanism. The placement seat is used to place the steel pipe, and the tilting drive mechanism is connected to the placement seat. Specifically, the placement seat is mounted on a frame, with one end hinged to the frame. The tilting drive mechanism includes a telescopic cylinder mounted on the frame, which is connected to the other end of the placement seat. During drainage, the telescopic cylinder drives the placement seat to tilt, causing the entire steel pipe to tilt, raising the inlet end and lowering the outlet end. The liquid inside the pipe flows naturally to the outlet end under gravity. This design fully utilizes gravity to assist drainage, significantly improving drainage efficiency, reducing high-pressure gas purging time, reducing high-purity gas consumption, and further compressing process operating costs.

[0025] VI. This invention employs a multi-stage residue reduction design, combining "overall tilting gravity drainage + adjustment of the lowest point of the outlet + high-pressure gas purging + steel pipe rotation assistance," to minimize the residual amount of ionic liquid inside the pipe and significantly improve the ionic liquid recovery rate. The fully sealed design ensures that the ionic liquid does not come into contact with air throughout the entire process from drainage and recovery to device reset, completely solving the problem of harmful gas volatilization. Each functional module has a simple structure and clear operating steps, allowing for seamless integration with existing surface modification production lines and demonstrating promising industrial application prospects. Attached Figure Description

[0026] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings to aid in understanding the objectives and advantages of the present invention, wherein:

[0027] Figure 1 This is a schematic diagram of the end discharge device structure according to an embodiment of the present invention;

[0028] Figure 2This is an enlarged view of the end of the steel pipe in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the slip ring structure according to an embodiment of the present invention.

[0030] The diagram labels are as follows: 1. Slip ring; 2. Slip ring outlet groove; 3. Collar ring; 4. Collar ring outlet hole; 5. Sealing ring; 6. Flow passage hole; 301. Sleeve fitting part; 302. Connecting part; 7. Core rod; 701. Locking end; 8. Fixing block; 9. First fastener; 10. Rubber ring; 11. Placement seat; 12. Frame; 13. Telescopic cylinder; 14. Rotary motor. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0032] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the construction shown in the accompanying drawings. The terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive.

[0033] refer to Figures 1 to 3 The present invention discloses an end-discharge device for reducing residual modified liquid on the inner surface of large-diameter steel pipes, comprising: a slip ring 1, rotatably mounted on the end of the steel pipe, the wall of the slip ring 1 abutting against the end face of the steel pipe end, and a slip ring outlet groove 2 formed on the wall of the slip ring 1. The slip ring outlet groove 2 is used to draw out the liquid inside the steel pipe when the wall of the slip ring 1 abuts against the end face of the steel pipe end. Specifically, when the wall of the slip ring 1 abuts against the end face of the steel pipe end, the outlet hole of the slip ring 1 extends outward from the inner wall of the steel pipe, and its length is greater than the wall thickness of the steel pipe; a collar 3, mounted on the end of the steel pipe, the collar 3 having a collar outlet hole 4, and the inner wall of the collar 3 being provided with a channel for... The slip ring 1 extends in the direction described above and communicates with the liquid outlet hole 4 of the collar ring. By rotating the slip ring 1, the liquid outlet groove 2 of the slip ring can be aligned with the liquid outlet hole 4 of the collar ring, thereby forming an outflow channel for liquid to flow out together with the flow channel. When draining liquid after the surface modification treatment is completed, the operator rotates the slip ring 1 to align the liquid outlet groove 2 of the slip ring with the liquid outlet hole 4 of the collar ring. At this time, the liquid in the steel pipe flows into the liquid outlet hole 4 of the collar ring through the flow channel, and then flows out to the external collection pipeline through the liquid outlet groove 2 of the slip ring. By rotating the slip ring 1 to adjust the position of the liquid outlet hole, the liquid outlet can always be at the lowest point, thereby reducing the ionic liquid residue at the bottom and dead corner areas of the pipe and reducing ionic liquid loss.

[0034] Ionic liquids release harmful gases and deteriorate upon contact with air. If the seal is not tight during discharge, it will cause environmental pollution and waste of the medium. Therefore, a sealing ring 5 is provided between the slip ring 1 and the collar 3. The sealing ring 5 has a flow-through hole 6, which corresponds to the outlet hole 4 of the collar. The collar 3 includes a fitting part 301 and a connecting part 302. The fitting part 301 is fitted onto the end of the steel pipe, and the connecting part 302 is fixedly connected to the sealing ring 5 by a third fastener. The sealing ring 5 is fixed to the collar 3, forming a rotational seal with the wall surface of the slip ring 1. When the slip ring 1 is rotated to align the slip ring outlet groove 2 with the collar outlet hole 4, the flow-through hole 6 on the sealing ring 5 connects with both, forming a complete outflow channel. When the slip ring 1 rotates to other positions, the sealing ring 5 blocks the channel, preventing liquid leakage. This ensures a smooth outflow channel while achieving excellent dynamic sealing performance, effectively preventing ionic liquid leakage and air contact, ensuring operator safety, and avoiding environmental pollution.

[0035] Of course, during the surface modification treatment of the steel pipe, the end device needs to be accurately aligned and kept stable to prevent sealing failure or misalignment of the liquid outlet due to loosening. Based on this, this embodiment also includes a mandrel 7 inserted inside the steel pipe. The length of the mandrel 7 is greater than the length of the steel pipe, and its two ends protrude from the steel pipe. Correspondingly, the slip ring 1 in this embodiment has an outlet hole for the mandrel 7 to pass through, while the remaining wall surface of the slip ring 1 closes the end of the steel pipe. A limiting device is provided on the mandrel 7 to keep the slip ring 1 always in contact with the steel pipe. The limiting device includes a fixing block 8, which is installed on the part of the mandrel 7 that protrudes from the steel pipe. The side wall of the fixing block 8 is provided with a first fastener 9, which is inserted into the fixing block 8 and abuts against the mandrel 7 to achieve the positioning and fixing of the fixing block 8 on the mandrel 7. The mandrel 7 penetrates the steel pipe as an installation reference, and the fixing block 8 is positioned on the mandrel 7 by the first fastener 9, thereby supporting and limiting the slip ring 1 so that the slip ring 1 always abuts against the end face of the steel pipe.

[0036] The mandrel 7 has locking ends 701 at both ends. The diameter of the locking ends 701 is smaller than the diameter of the mandrel 7 body. The locking ends 701 pass through the fixing block 8 and are equipped with at least one second fastener (nut) for locking. After the locking ends 701 at both ends of the mandrel 7 pass through the fixing block 8, they are locked by the second fastener to prevent the fixing block 8 from moving axially. This achieves precise alignment and reliable fixation of the device at the end of the steel pipe, ensuring that the slip ring 1 always keeps a tight contact with the end face of the steel pipe, avoiding sealing failure and misalignment of the liquid outlet due to loosening, and improving the stability and reliability of the device.

[0037] A rubber ring 10 is provided between the second bolt and the fixing block 8. The rubber ring 10 is frustum-shaped, and its reduced diameter end is inserted into the fixing block 8. When the reduced diameter end of the frustum-shaped rubber ring 10 is inserted into the fixing block 8, it generates a pre-tightening force when the second fastener is tightened, which further enhances the sealing and anti-loosening effect.

[0038] Furthermore, when the steel pipe is placed horizontally, the liquid inside the pipe is affected by gravity distribution. If the outlet end cannot be in a low position, it is still difficult to completely drain the liquid by simply rotating the slip ring 1. Based on this, this embodiment also includes a placement seat 11 and a tilting drive mechanism. The placement seat 11 is used to place the steel pipe, and the tilting drive mechanism is connected to the placement seat 11 to drive the placement seat 11 to tilt. Specifically, it also includes a frame 12, on which the placement seat 11 is mounted, and one end of the placement seat 11 is hinged to the frame 12. The tilting drive mechanism includes a telescopic cylinder 1 mounted on the frame 12. 3. The telescopic cylinder 13 is connected to the other end of the placement seat 11. The telescopic cylinder 13 controls the tilting of the placement seat 11. When the steel pipe is placed on the placement seat 11, the telescopic cylinder 13 is activated during drainage. The motor extends or retracts, driving the placement seat 11 to rotate around the hinge point, causing the placement seat 11 and the steel pipe to tilt as a whole. The inlet end is raised and the outlet end is lowered. At this time, the slip ring 1 is rotated to align the outlet hole. The liquid in the pipe flows more smoothly to the outlet under the action of gravity, making full use of gravity to assist drainage, significantly improving drainage efficiency, reducing the amount of high-purity gas used for purging, and reducing process operating costs.

[0039] A rotary motor 14 is mounted on the placement base 11. A transmission gear is installed at the output end of the rotary motor 14 to drive the steel pipe to rotate. Specifically, after installation, the transmission gear is located on the output shaft of the rotary motor 14, and a driven gear is positioned around the outer circumference of the steel pipe to mesh with it. Driven by the rotary motor 14, the transmission gear drives the steel pipe to rotate around its own axis. Alternatively, a transmission belt can be installed between the two, with the belt wound around both the transmission gear and the driven gear to form a belt drive structure, thereby driving the steel pipe to rotate around its own axis. During the drainage process, when it is necessary to adjust the position of the outlet or inlet of the steel pipe, the rotating motor 14 is started. The gear transmission makes the steel pipe rotate smoothly, thereby rotating the preset outlet or inlet to adjust the outlet 4 of the collar to a downward position. Of course, in actual operation, it is also necessary to control the mandrel 7 to remain fixed, that is, the steel pipe and the mandrel 7 rotate relative to each other. During the drainage process, the rotating motor 14 is started, and the transmission gear drives the steel pipe to rotate slowly around the mandrel 7 to adjust the angle so that the outlet 4 of the collar is always at the lowest point of the steel pipe cross-section.

[0040] Working principle:

[0041] Step 1: Equipment Installation and Initial Preparation

[0042] The end discharge device (including slip ring 1, collar 3, sealing ring 5 and mandrel 7 limiting structure) described in this embodiment is installed at both ends of the steel pipe. The mandrel 7 and the fixing block 8 ensure that the slip ring 1 at both ends is tightly against the end face of the steel pipe to form a reliable initial seal. The steel pipe with the end device installed is hoisted onto the placement seat 11.

[0043] Step 2: Tilt the whole body (flip-driven)

[0044] Start the flipping drive mechanism (telescopic cylinder 13) to drive the placement seat 11 to flip around one of its hinge points, so that the placement seat 11 and the steel pipe are tilted as a whole; at this time, one end of the steel pipe (liquid inlet end) is raised to become the higher end, and the other end (liquid outlet end) is lowered to become the lower end; this tilting posture makes full use of gravity, so that the liquid in the pipe flows naturally to the lower end.

[0045] Step 3: Adjust the liquid outlet (rotate the steel pipe + rotate slip ring 1)

[0046] At the outlet end (lower end), the rotating motor 14 is started first, which drives the steel pipe to rotate slowly through the transmission gear. When the steel pipe rotates, the collar 3 installed at its end rotates accordingly. When the outlet hole 4 of the collar rotates to the lowest point (directly below), the rotating motor 14 is stopped, so that the outlet hole 4 of the collar is locked in the optimal drainage direction.

[0047] Subsequently, the slip ring 1 at this end is rotated so that the slip ring outlet groove 2 on the slip ring 1 is aligned with the outlet hole 4 of the collar. At this time, the slip ring outlet groove 2, the flow passage hole 6 on the sealing ring 5, and the outlet hole 4 of the collar are connected, forming a complete outflow channel together with the guide channel on the inner wall of the collar 3. The liquid can flow out to the external collection pipeline through this channel.

[0048] Step 4: Adjust the inlet end (rotate the steel pipe + rotate slip ring 1)

[0049] At the liquid inlet end (higher end), the rotating motor 14 is also started, driving the steel pipe to rotate through the transmission gear, so that the liquid outlet hole 4 of the collar rotates to the appropriate position (usually downward or towards the direction that is convenient for connecting the gas source). Then, the slip ring 1 is rotated so that the slip ring liquid outlet groove 2 is aligned with the liquid outlet hole 4 of the collar, forming a gas inlet channel; the liquid inlet hole at this end (i.e. the original liquid outlet hole 4 of the collar) is connected to a high-pressure gas source (such as high-purity nitrogen) as the inlet of the purging gas.

[0050] Step 5: Combined Gravity Drainage and Gas Purging

[0051] Under the influence of gravity, most of the ionic liquid inside the steel pipe is discharged from the outlet end through the outlet channel; when the gravity drainage slows down, high-pressure gas is introduced from the inlet end, and the gas flows along the inside of the steel pipe to the outlet end, forcibly purging the residual ionic liquid on the inner wall of the pipe and in the dead corners of the structure.

[0052] During the gas purging process, the slip ring liquid outlet groove 2 at the liquid outlet end is aligned with the collar liquid outlet hole 4. The gas carrying the residual liquid is continuously discharged through the outflow channel until no liquid flows out of the pipe.

[0053] Step 6: Drainage completed

[0054] Turn off the high-pressure gas source and disconnect the gas line connection at the liquid inlet; if necessary, rotate slip ring 1 to close the liquid outlet channel, or restore the device to its initial state to prepare for the next surface modification treatment.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An end-discharge device for reducing residual modified liquid on the inner surface of large-diameter steel pipes, characterized in that, include: A slip ring (1) is rotatably installed at the end of a steel pipe. The wall of the slip ring (1) abuts against the end face of the end of the steel pipe. A slip ring outlet groove (2) is provided on the wall of the slip ring (1) for drawing out the liquid inside the steel pipe. A collar (3) is installed at the end of a steel pipe. The collar (3) is provided with a collar outlet hole (4). The inner wall of the collar (3) is provided with a guide channel that extends toward the slip ring (1) and communicates with the collar outlet hole (4). By rotating the slip ring (1), the slip ring outlet groove (2) can be aligned with the sleeve outlet hole (4), thereby forming an outlet channel for liquid to flow out together with the guide channel.

2. The end discharge device for reducing the residue of modified liquid on the inner surface of large-diameter steel pipes according to claim 1, characterized in that: A sealing ring (5) is provided between the slip ring (1) and the collar (3), and a flow hole (6) is provided on the sealing ring (5), which corresponds to the liquid outlet hole (4) of the collar.

3. The end discharge device for reducing residual modified liquid on the inner surface of large-diameter steel pipes according to claim 2, characterized in that: The collar (3) includes a sleeve part (301) and a connecting part (302). The sleeve part (301) is sleeved on the end of the steel pipe, and the connecting part (302) is fixedly connected to the sealing ring (5) by a third fastener.

4. The end discharge device for reducing the residue of modified liquid on the inner surface of large-diameter steel pipes according to claim 1, characterized in that: It also includes a mandrel (7) inserted inside the steel pipe, the length of which is greater than the length of the steel pipe, and both ends of which protrude from the steel pipe; The mandrel (7) is provided with a limiting device, which is used to keep the slip ring (1) always abutting against the end face of the steel pipe.

5. The end discharge device for reducing residual modified liquid on the inner surface of large-diameter steel pipes according to claim 4, characterized in that: The limiting device includes a fixing block (8), which is installed on the part of the mandrel (7) that protrudes from the steel pipe. The side wall of the fixing block (8) is provided with a first fastener (9), which is inserted into the fixing block (8) and abuts against the mandrel (7) to achieve the positioning and fixing of the fixing block (8) on the mandrel (7).

6. The end discharge device for reducing residual modified liquid on the inner surface of large-diameter steel pipes according to claim 5, characterized in that: The core rod (7) has locking ends (701) at both ends. The diameter of the locking end (701) is smaller than the body diameter of the core rod (7). The locking end (701) extends through the fixing block (8) and is provided with at least one second fastener for locking.

7. The end discharge device for reducing residual modified liquid on the inner surface of large-diameter steel pipes according to claim 6, characterized in that: A rubber ring (10) is provided between the second fastener and the fixed block (8). The rubber ring (10) is frustum-shaped and its reduced-diameter end is inserted into the fixed block (8).

8. The end discharge device for reducing the residue of modified liquid on the inner surface of large-diameter steel pipes according to claim 1, characterized in that: It also includes a placement seat (11) and a flipping drive mechanism. The placement seat (11) is used to place the steel pipe, and the flipping drive mechanism is connected to the placement seat (11) and is used to drive the placement seat (11) to flip and tilt.

9. The end discharge device for reducing residual modified liquid on the inner surface of large-diameter steel pipes according to claim 8, characterized in that: It also includes a frame (12), the placement seat (11) is mounted on the frame (12), one end of the placement seat (11) is hinged to the frame (12); the flipping drive mechanism includes a telescopic cylinder (13) mounted on the frame (12), the telescopic cylinder (13) is connected to the other end of the placement seat (11), and the tilting of the placement seat (11) is controlled by the telescopic cylinder (13).

10. An end discharge device for reducing residual modified liquid on the inner surface of large-diameter steel pipes according to claim 8, characterized in that: A rotating motor (14) is provided on the placement seat (11), and a transmission gear is provided at the output end of the rotating motor (14). The transmission gear is used to drive the steel pipe to rotate.

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