Automatic production line for enamel fixed-length steel pipes

Abstract

The utility model discloses an automatic production line for enamel fixed-length steel pipes, which belongs to the technical field of enamel pipe production and comprises a conveying chain and a conveying track, the conveying chain moves on the conveying track and is sequentially provided with a feeding area, an enameling area, a drying area, a firing area and a discharging area along the conveying direction of the conveying chain, and the conveying track comprises a U-shaped temperature expansion joint. The U-shaped temperature telescopic connector is located between the enameling area and the drying area, sliding sleeves are fixedly connected to the two ends of the U-shaped temperature telescopic connector correspondingly, the ends, away from the U-shaped temperature telescopic connector, of the sliding sleeves are slidably connected with the linear rail, rotating blocks are arranged on the two inner side faces of the sliding sleeves, protrusions are arranged on the rotating blocks, and a plurality of limiting blocks are arranged on the two outer side faces of the linear rail correspondingly. The limiting block is provided with a groove used in cooperation with the protrusion. By means of the protrusions, the limiting blocks and the grooves, the conveying track can be lengthened by different lengths, the defect that the conveying chain is not matched with the conveying track due to thermal deformation is overcome, and meanwhile normal work of all areas of a production line cannot be affected.

Description

Technical Field

[0001] The utility model relates to the technical field of enamel tube production, in particular to an automatic production line for enamel cut-to-length steel pipes. Background Art

[0002] Enamel tubes have the characteristics of smooth surface and not easy to deposit, which can prevent scale formation inside the pipeline, reduce the situation of pipeline blockage, and the enamel tubes have strong corrosion resistance and can be used for a long time without being corroded, increasing the service life of the pipeline. Based on the above advantages, enamel tubes are widely used in the field of heat exchange equipment. Due to the increasing demand for customized enamel tubes of specific lengths, the requirements for the skills and physical strength of operators are also getting higher and higher. Therefore, people have started to carry out the automated production of enamel tubes.

[0003] When the conveyor chain in the enamel tube automated production line passes through the high-temperature area, it is prone to heat deformation, resulting in a mismatch with the corresponding conveyor track, reducing the service life of the conveyor chain and lowering the production efficiency; when the enamel tube is sintered, it is mostly directly heated by natural gas, and the temperature cannot be accurately controlled, with weak controllability, resulting in a decline in the quality of the enamel tube.

[0004] In view of the problems existing in the above-mentioned prior art, the utility model combines the design and use experience in related fields for many years and designs an automatic production line for enamel cut-to-length steel pipes to overcome the above defects. Summary of the Utility Model

[0005] For the problems existing in the prior art, the automatic production line for enamel cut-to-length steel pipes provided by the utility model can overcome the disadvantages that the conveyor chain is deformed by heat in the high-temperature area and does not match the conveyor track, extend the service life of the conveyor chain, make the conveyor chain move more flexibly, improve the production efficiency, and can also accurately control the temperature during the sintering of the cut-to-length steel pipe, improving the quality of the enamel of the cut-to-length steel pipe.

[0006] In order to achieve the above object, the technical scheme adopted by the utility model is as follows: an automatic production line for enamel cut-to-length steel pipes, including a conveyor chain, a conveyor track and a fixing frame;

[0007] The conveyor chain moves on the conveyor track, and the fixing frame is located above the conveyor track;

[0008] A loading area, an enameling area, a drying area, a firing area and an unloading area are sequentially arranged along the conveying direction of the conveyor chain;

[0009] The conveyor track includes a U-shaped temperature expansion joint;

[0010] The U-shaped temperature expansion joint is located between the enameling area and the drying area;

[0011] Both ends of the U-shaped temperature expansion joint are fixedly connected with sliding sleeves, and one end of each sliding sleeve far away from the U-shaped temperature expansion joint is slidably connected with a linear track;

[0012] Rotating blocks are respectively arranged on two inner side surfaces of each sliding sleeve. One end of each rotating block is rotatably connected with the sliding sleeve, and a protrusion is arranged at the other end;

[0013] A plurality of groups of limiting blocks are respectively arranged on two outer side surfaces of the linear track, and each group of limiting blocks is arranged on the linear track at intervals;

[0014] One group of the limiting blocks includes a first limiting block and a second limiting block, and the first limiting block and the second limiting block are arranged in sequence along the conveying direction of the conveying chain;

[0015] The side surface of the first limiting block far away from the U-shaped temperature expansion joint is in a slope shape from low to high. The lowest point of the slope-shaped side surface is on the same horizontal plane as the lower surface of the linear track, and a channel only allowing the protrusion to pass through is arranged between the highest point of the slope-shaped side surface and the second limiting block;

[0016] A groove matched with the protrusion is arranged on the side surface of the second limiting block far away from the U-shaped temperature expansion joint, and gaps allowing the protrusion to pass through are respectively left between the side surface of the first limiting block close to the U-shaped temperature expansion joint and the side surface where the groove is located and between the lower surface of the second limiting block and the lower surface of the linear track;

[0017] When the sliding sleeve slides, the side surfaces where the protrusions on the rotating blocks are located are respectively in contact with the outer side surfaces of the first limiting block and the outer side surfaces of the second limiting block;

[0018] It includes a spring. Two ends of the spring are respectively fixedly connected to the linear track and the sliding sleeve, and the spring is in a tensioned state;

[0019] A horizontally outward tensioning mechanism with variable force is arranged at the inflection point of the U-shaped temperature expansion joint.

[0020] Preferably, the horizontally outward tensioning mechanism includes a hook, a steel wire rope, a pulley and a plurality of counterweights;

[0021] The hook is fixed at the inflection point of the U-shaped temperature expansion joint, the pulley is fixed on a fixed frame, the hook and the plurality of counterweights are connected by a steel wire rope, the number of the counterweights at the end of the steel wire rope is adjustable, and the steel wire rope is hung on the pulley.

[0022] Preferably, the conveying track is provided with a plurality of 180° turning tracks;

[0023] A steering structure is arranged on the 180° turning track;

[0024] The steering structure includes a fixed shaft and a steering wheel;

[0025] The fixed shaft is vertically and fixedly connected to the fixed frame, and the steering wheel is sleeved on the fixed shaft and rotates around the fixed shaft;

[0026] A groove is provided on the outer edge of the steering wheel, and an arc-shaped limiting groove is formed between the 180° turning track and the groove;

[0027] The conveying chain is located in the groove.

[0028] Preferably, a plurality of furnace bodies are provided in the firing zone, and a furnace lining is provided in the furnace body;

[0029] The furnace lining is composed of high-purity refractory fiber folding blocks.

[0030] Preferably, a plurality of "N"-shaped electric heating elements are embedded in the furnace lining. The "N"-shaped electric heating elements are connected end to end and arranged around the furnace lining. The "N"-shaped electric heating elements are fixed in the furnace lining by magnetic nails.

[0031] Preferably, a temperature controller is further included, and the temperature controller automatically controls the temperatures of the drying zone and the firing zone.

[0032] Preferably, a high-temperature radiation layer is provided on the inner surface of the furnace lining.

[0033] Preferably, a plurality of hot air blowers are provided in the firing zone. A heat supply pipeline is connected to the air outlet of the hot air blower, and the hot air blower and the drying zone are connected through the heat supply pipeline.

[0034] Preferably, a plurality of temperature measuring instruments are provided in both the drying zone and the firing zone.

[0035] The beneficial effects of the utility model are as follows:

[0036] 1. Through the U-shaped temperature expansion joint and the sliding sleeve of the utility model, the sliding of the U-shaped temperature expansion joint is realized. The steering blocks on the sliding sleeve are respectively used in cooperation with the limiting blocks on the straight track to realize the extension of different lengths of the conveying track, so that the conveying chain is always in a tensioned state, avoiding the deformation of the conveying chain due to heat or long-term operation and the mismatch with the conveying track.

[0037] 2. The utility model adds a steering structure, enabling the conveying chain to operate smoothly at the 180° turning track, improving production efficiency.

[0038] 3. The utility model adopts electric heating elements, uses the temperature controller to set the temperatures in the drying zone and the firing zone, monitors and adjusts the temperature in real time, realizes precise temperature control, improves the quality of enameling of fixed-length steel pipes, provides a high-temperature radiation layer on the inner surface of the furnace lining, enhances the erosion resistance of the furnace lining, improves the service life of the furnace lining, and enhances the heat preservation performance; the electric heating elements in the furnace lining are in an "N" shape, enabling the fixed-length steel pipes to be heated evenly during sintering, with good sintering effect, and can significantly improve the quality of enameling of fixed-length steel pipes.

[0039] 4. The utility model transfers the waste heat in the firing area to the drying area through a hot air blower, which serves as the first heat source in the drying area to preheat the enamel cut-to-length steel pipe, effectively utilizing the waste heat after the sintering of the cut-to-length steel pipe and reducing the heat energy consumption. Description of the Drawings

[0040] Figure 1 It is a schematic diagram of an automatic production line for enamel cut-to-length steel pipes.

[0041] Figure 2 It is a bottom view of a U-shaped temperature expansion joint in an automatic production line for enamel cut-to-length steel pipes.

[0042] Figure 3 It is a front view of a U-shaped temperature expansion joint in an automatic production line for enamel cut-to-length steel pipes.

[0043] Figure 4 It is a front view of a sliding sleeve in an automatic production line for enamel cut-to-length steel pipes.

[0044] Figure 5 It is a bottom view of a steering structure in an automatic production line for enamel cut-to-length steel pipes.

[0045] In the figure: 1 - loading area, 2 - enameling area, 3 - drying area, 4 - repair area, 5 - firing area, 6 - unloading area, 7 - U-shaped temperature expansion joint, 8 - sliding sleeve, 9 - hook, 10 - counterweight, 11 - steel wire rope, 12 - linear track, 13 - fixing frame, 14 - pulley, 15 - rotating block, 16 - protrusion, 17 - first limit block, 18 - second limit block, 19 - groove, 20 - limit groove, 21 - fixed shaft, 22 - steering wheel, 23 - conveyor chain, 24 - 180° turning track, 25 - spring. Detailed Embodiment

[0046] For the convenience of those skilled in the art to understand, the following further describes the present utility model in conjunction with the accompanying drawings.

[0047] An automatic production line for enameled fixed-length steel pipes, comprising a conveying chain, a conveying track, and a fixing frame 13. The conveying chain 23 moves on the conveying track. The fixing frame 13 is located above the conveying track. A loading area 1, an enameling area 2, a drying area 3, a firing area 5, and a blanking area 6 are sequentially arranged along the conveying direction of the conveying chain 23. The conveying track includes a U-shaped temperature expansion joint 7 and several straight tracks 12. The U-shaped temperature expansion joint 7 is located between the enameling area 2 and the drying area 3. Both ends of the U-shaped temperature expansion joint 7 are fixedly connected with sliding sleeves 8. One end of the sliding sleeve 8 away from the U-shaped temperature expansion joint 7 is slidably connected with the straight track 12. Rotating blocks 15 are respectively arranged on the inner sides of the two sliding sleeves 8. One end of the rotating block 15 is rotatably connected with the sliding sleeve 8, and the other end is provided with a protrusion 16. Several groups of limiting blocks are respectively arranged on the outer sides of the two straight tracks 12. Each group of limiting blocks is arranged at intervals on the straight track 12. A group of limiting blocks includes a first limiting block 17 and a second limiting block 18. The first limiting block 17 and the second limiting block 18 are arranged in sequence along the conveying direction of the conveying chain 23. The side of the first limiting block 17 away from the U-shaped temperature expansion joint 7 is a slope-shaped surface from low to high. The lowest point of the slope-shaped surface is on the same horizontal plane as the lower surface of the straight track 12. A passage for only the protrusion 16 to pass through is provided between the highest point and the second limiting block 18. A groove 19 for cooperating with the protrusion 16 is provided on the side of the second limiting block 18 away from the U-shaped temperature expansion joint 7. A gap for the protrusion 16 to pass through is left between the side of the first limiting block 17 close to the U-shaped temperature expansion joint 7 and the side where the groove 19 is located, and between the lower surface of the second limiting block 18 and the lower surface of the straight track 12. When the sliding sleeve 8 slides, the side where the protrusion 16 is located on the rotating block 15 is respectively in contact with the outer side of the first limiting block 17 and the outer side of the second limiting block 18, including a spring 25. Both ends of the spring 25 are respectively fixedly connected to the straight track 12 and the sliding sleeve 8. The spring 25 is in a tensioned state. A horizontally outward tensioning mechanism with a variable force is provided at the inflection point of the U-shaped temperature expansion joint 7.

[0048] The horizontal outward tensioning mechanism includes a hook 9, a steel wire rope 11, a pulley 14 and a number of counterweights 10. The hook 9 is arranged at the inflection point of the U-shaped temperature expansion joint 7. The pulley 14 is fixed on the fixed frame 13. The hook 9 and the number of counterweights 10 are connected by the steel wire rope 11. The number of counterweights 10 at the end of the steel wire rope 11 is adjustable. The steel wire rope 11 is hung on the pulley 14. The conveying track is provided with a number of 180° turning tracks 24. The 180° turning track 24 is provided with a steering structure. The steering structure includes a fixed shaft 16 and a steering wheel 17. The fixed shaft 16 is vertically and fixedly connected to the fixed frame 13. The steering wheel 17 is sleeved on the fixed shaft 16 and rotates around the fixed shaft 16. A groove is provided around the outer edge surface of the steering wheel 17. An arc-shaped limiting groove 15 is formed between the 180° turning track 24 and the groove. The conveying chain 23 is located in the groove. The firing area 5 is provided with a number of furnace bodies. The furnace body is provided with a furnace lining. The furnace lining is composed of high-purity refractory fiber folding blocks. A number of "N"-shaped electric heating elements are embedded in the furnace lining. The "N"-shaped electric heating elements are connected end to end and arranged around the furnace lining. They are fixed in the furnace lining by magnetic nails. It also includes a temperature controller. The temperature controller automatically controls the temperatures of the drying area 3 and the firing area 5. A high-temperature radiation layer is provided on the inner surface of the furnace lining. A number of hot air blowers are provided on the firing area 5. A heat supply pipeline is connected to the outlet of the hot air blower. The hot air blower and the drying area 3 are connected by the heat supply pipeline. A number of temperature measuring instruments are provided in both the drying area 3 and the firing area 5.

[0049] Specifically, the pulley 14 changes the acting direction of the force of the counterweight 10 from vertically downward to horizontally outward. Therefore, under the action of the counterweight 10, the U-shaped temperature expansion joint 7 moves outward through the sliding sleeve 8, away from the linear track 12, extending the length of the conveying track. At the initial stage, the rotating block 15 on the sliding sleeve 8 faces the first limit block 17. When the sliding sleeve 8 is subjected to the force of the horizontal pulling mechanism, the protrusion 16 on the rotating block 15 rises along the sloping side surface of the first group of the first limit blocks 17 to the highest point. When the protrusion 16 passes the highest point, it slowly falls under the action of gravity. Since the gap between the highest point of the first limit block 17 and the second limit block 18 is small, the protrusion 16 can be successfully engaged with the groove 19 on the first group of the second limit blocks 18 under the pulling of the horizontally outward force. At this time, the conveyor chain 23 is in a tensioned state. When the conveyor chain 23 is no longer in a tensioned state after running for a period of time, it is necessary to continue to slide the sliding sleeve 8 to reduce the weight of the counterweight 10, so that the pulling force of the spring 25 on the sliding sleeve 8 is greater than the force of the horizontal pulling mechanism. At this time, the protrusion 16 will leave the groove 19 on the first group of the second limit blocks 18, and at the same time, under the action of gravity, the protrusion 16 falls from the gap between the side surface of the first group of the first limit blocks 17 close to the U-shaped temperature expansion joint 7 and the side surface where the groove 19 is located to the bottom of the first group of the first limit blocks 17. At this time, the weight of the counterweight 10 is increased, the force of the horizontal pulling mechanism is greater than the force of the spring 25, and the sliding sleeve 8 drives the protrusion 16 to pass through the gap between the lower surface of the first group of the second limit blocks 18 and the lower surface of the linear track 12, and rises along the sloping side surface of the second group of the first limit blocks 17 to the highest point, and then engages with the second group of grooves 19, completing the second tensioning of the conveyor chain 23. By setting several groups of limit blocks, the conveyor chain 23 can be tensioned multiple times, so that the conveyor chain 23 is always in a tensioned state during the production process, avoiding the occurrence of a gap between the conveyor chain 23 and the conveying track due to thermal deformation or long-term operation deformation. The U-shaped temperature expansion joint 7 is arranged between the enameling area 2 and the drying area 3, without affecting the normal operation of other areas of the production line.

[0050] The conveyor chain 23 drives the steering wheel 17 to rotate through friction, reducing the resistance of the conveyor chain 23 when changing direction on the 180° turning track 24, enabling the conveyor chain 23 to operate smoothly on the entire conveying track and improving production efficiency. The furnace lining is composed of high-purity refractory fiber folding blocks, with good energy-saving effect. The electric heating element is in an "N" shape, which can uniformly heat the fixed-length steel pipe, with good sintering effect. Through the temperature controller, the temperatures in the drying area 3 and the firing area 5 are set, and the temperature is monitored and adjusted in real time to achieve precise temperature control and improve the quality of the fixed-length steel pipe enamel.

[0051] Setting a high-temperature radiation layer on the inner surface of the furnace lining can enhance the erosion resistance of the furnace lining, extend the service life of the furnace lining, and enhance the heat preservation performance. The utility model makes full use of the heat in the firing zone 5, and sends the heat dissipated from the sintered sizing steel pipes out of the furnace through a hot air blower to the workstations in the drying zone 3 to preheat the sizing steel pipes in the drying zone 3, reducing heat waste.

[0052] The conveying chain 23 of the utility model is a suspended conveying chain, and the sizing steel pipes are transmitted in a suspended manner. The conveying chain 23 and the automatic enameling machine are controlled by a PLC. The PLC control is arranged in a control cabinet. The conveying chain 23 is made to work intermittently through the PLC controller. The conveying chain 23 accurately moves to the enameling zone 2 and then stops slowly. After the conveying chain 23 stops, the enameling machine performs the enameling work on the sizing steel pipes, realizing the automatic enameling and transmission of the sizing steel pipes. The drying zone 3 is provided with a number of air curtain machines. The air curtain machines adopt the method of gentle blowing on both sides, so that the enameling effect on the surface of the sizing steel pipes is good, there is no enameling flow, and the drying effect is remarkable. The firing zone 5 is provided with a number of air curtain machines. The air curtain machines adopt the method of blowing on both sides, which can effectively prevent the temperature convection in the firing zone 5. A repair area 4 is also provided between the drying zone 3 and the firing zone 5. Workers check the enameling quality of the sizing steel pipes in the repair area 4, and manually repair the sizing steel pipes with defective enameling.

[0053] The specific working process is as follows:

[0054] The horizontal tension mechanism pulls the U-shaped temperature expansion joint 7 to slide outwards, and the protrusion 16 slides over the first group of first limit blocks 17 and is clamped with the notch 19 of the first group of second limit blocks 18. At this time, the conveying chain 23 is in a tensioned state, and then the following steps are carried out:

[0055] S1 Pipe hanging: In the loading area 1, the processed sizing steel pipes are successively hung on the conveying chain 23. The conveying chain 23 adopts a QXG200 heavy-duty conveying chain, with a pitch of 200 mm, a track of 100 mm * 80 mm * 5 mm, and the conveying chain 23 adopts a variable-frequency speed-regulating motor;

[0056] S2 Automatic enameling: The conveying chain 23 hanging with the sizing steel pipes accurately moves to the enameling zone 2 and then stops slowly. The sizing steel pipes are conveyed to the enameling zone 2 for internal and external surface enameling. The enameling zone 2 is provided with 66 enameling workstations, and each enameling workstation is provided with two groups of enameling machines. One group is selected for work during production. One group of enameling machines includes an outer wall enameling machine and an inner wall enameling machine. Each group of enameling machines can simultaneously enamel 11 sizing steel pipes. The enameling zone 2 is 24 meters in total. After enameling, the sizing steel pipes stay for a delay under the condition of meeting the firing set time to make the enamel slurry level.

[0057] S3 Drying: The cut-to-length steel pipes that have completed step S2 are conveyed to the drying area 3. The waste heat from the firing area 5 is transferred to the drying area 3 by a hot air blower to preheat the cut-to-length steel pipes, and then the drying of the cut-to-length steel pipes is completed using electric heating elements. The set temperature of the drying area 3 is 90 - 130 °C;

[0058] S4 Repair: The dried cut-to-length steel pipes are conveyed to the repair area 4. The effective length of the repair area 4 is 12 meters, and the cut-to-length steel pipes with defective enameling are manually repaired here.

[0059] S5 Sintering: The repaired cut-to-length steel pipes are conveyed to the firing area 5 for high-temperature sintering. The firing area 5 is U-shaped, with a heating power of 2250 KW. The temperature of the firing area 5 is set at 700 - 900 °C and can be monitored and adjusted in real time through a PLC;

[0060] S6 Cooling: The temperature of the cut-to-length steel pipes is lower than 50 °C when they reach the offline station after cooling down.

[0061] S7 Pipe Unloading: The cut-to-length steel pipes that have completed step S6 are conveyed to the blanking area 6, and the enameled cut-to-length steel pipes are obtained.

[0062] When the long-term operation causes the conveyor chain 23 to be mismatched with the conveyor track, the weight of the counterweight iron 10 is changed, so that the sliding sleeve 8 rebounds under the action of the spring 25, and the protrusion 16 on the rotating block 15 falls to the bottom of the first group of first limit blocks 17. Then, the weight of the counterweight iron 10 is increased, and the force of the horizontal tension mechanism is greater than the force of the spring 25. The sliding sleeve 8 drives the protrusion 16 on the rotating block 15 to pass through the gap between the lower surface of the second group of second limit blocks 18 and the lower surface of the linear track 12 and is clamped with the groove 19 of the second group of second limit blocks 18 to complete the second tensioning of the conveyor chain 23.

[0063] It should be understood that the use of these embodiments is only for illustrating the present invention and is not intended to limit the protection scope of the present invention. In addition, it should also be understood that after reading the technical content of the present invention, those skilled in the art can make various changes, modifications, and / or variations to the present invention, and all these equivalent forms also fall within the protection scope defined by the appended claims of this application.

Claims

1. An automatic production line for enameled steel pipes, characterized in that: It comprises a conveying chain (23), a conveying track and a fixing frame (13); The conveying chain (23) moves on the conveying track, and the fixing frame (13) is located above the conveying track; A loading area (1), an enameling area (2), a drying area (3), a sintering area (5) and a unloading area (6) are sequentially arranged along the conveying direction of the conveying chain (23); The conveying track is provided with a U-shaped temperature expansion joint (7); The U-shaped temperature expansion joint (7) is located between the enameling area (2) and the drying area (3); Both ends of the U-shaped temperature expansion joint (7) are respectively fixedly connected with a sliding sleeve (8), and one end of the sliding sleeve (8) away from the U-shaped temperature expansion joint (7) is slidably connected with a linear track (12); The two inner sides of the sliding sleeve (8) are respectively provided with rotating blocks (15), one end of the rotating block (15) is rotatably connected to the sliding sleeve (8), and the other end is provided with a protrusion (16); A plurality of groups of limit blocks are respectively arranged on the two outer sides of the linear track (12), and each group of limit blocks is arranged at intervals on the linear track (12); A group of the limit blocks comprises a first limit block (17) and a second limit block (18), wherein the first limit block (17) and the second limit block (18) are arranged in sequence along the conveying direction of the conveying chain (23); The side of the first limit block (17) away from the U-shaped temperature expansion joint (7) is sloping from low to high, the lowest point of the sloping side surface is on the same horizontal plane as the lower surface of the linear track (12), and a channel is provided between the highest point of the sloping side surface and the second limit block (18) for only the protrusion (16) to pass through; A groove (19) for use with the protrusion (16) is provided on the side of the second limit block (18) away from the U-shaped temperature expansion joint (7), and a gap for the protrusion (16) to pass through is left between the side of the first limit block (17) close to the U-shaped temperature expansion joint (7) and the side where the groove (19) is located, and between the lower surface of the second limit block (18) and the lower surface of the linear track (12); When the sliding sleeve (8) slides, the side surface of the protrusion (16) on the rotating block (15) contacts the outer side surface of the first limiting block (17) and the outer side surface of the second limiting block (18) respectively; It comprises a spring (25), the two ends of which are respectively fixedly connected to the linear track (12) and the sliding sleeve (8), and the spring (25) is in a tensioned state; A horizontal outward tensioning mechanism with variable force is provided at the inflection point of the U-shaped temperature expansion joint (7).

2. The automatic production line for enameled steel pipes of fixed length according to claim 1 is characterized in that: The horizontal outward tensioning mechanism comprises a draw hook (9), a steel wire rope (11), a pulley (14) and a plurality of counterweight irons (10); The draw hook (9) is fixed at the inflection point of the U-shaped temperature expansion joint (7), the pulley (14) is fixed on the fixing frame (13), the draw hook (9) and a plurality of counterweights (10) are connected via a steel wire rope (11), the number of counterweights (10) located at the end of the steel wire rope (11) is adjustable, and the steel wire rope (11) is hung on the pulley (14).

3. The automatic production line for enameled cut-to-length steel pipes according to claim 1 is characterized in that: The conveying track also includes a plurality of 180° turning tracks (24); The 180° turning track (24) is provided with a steering structure; The steering structure comprises a fixed shaft (21) and a steering wheel (22); The fixed shaft (21) is vertically fixedly connected to the fixed frame (13); the steering wheel (22) is sleeved on the fixed shaft (21) and rotates around the fixed shaft (21); and a groove is provided on the outer edge of the steering wheel (22); An arc-shaped limiting groove (20) is formed between the 180° turning track (24) and the groove, and the conveying chain (23) is located in the groove.

4. The automatic production line for enameled steel pipes of claim 1 is characterized in that: The sintering zone (5) is provided with a plurality of furnace bodies, wherein the furnace bodies are provided with furnace linings, and the furnace linings are composed of high-purity refractory fiber folded blocks.

5. The automatic production line for enameled steel pipes of claim 4 is characterized in that: A plurality of "N"-shaped electric heating elements are embedded in the furnace lining. The "N"-shaped electric heating elements are connected end to end and arranged around the furnace lining. The "N"-shaped electric heating elements are fixed in the furnace lining by magnetic nails.

6. The automatic production line for enameled steel pipes of claim 1 is characterized in that: It also includes a temperature controller, which automatically controls the temperature of the drying area (3) and the sintering area (5).

7. The automatic production line for enameled cut-to-length steel pipes according to claim 4 is characterized in that: A high-temperature radiation layer is provided on the inner surface of the furnace lining.

8. The automatic production line for enameled cut-to-length steel pipes according to claim 1 is characterized in that: The sintering area (5) is provided with a plurality of hot air blowers, the air outlets of the hot air blowers are connected with heat supply pipes, and the hot air blowers and the drying area (3) are connected via the heat supply pipes.

9. The automatic production line for enameled cut-to-length steel pipes according to claim 1 is characterized in that: The drying area (3) and the sintering area (5) are both provided with a plurality of temperature measuring instruments.

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