Self-circulating nitrogen heating system and heating method for vulcanizing machine

Abstract

The invention discloses a self-circulating nitrogen heating system and a heating method for a vulcanizing machine. The heating system comprises an air supply pipeline, which is connected with a low-pressure air intake device and a high-pressure air intake device; a radiator, a gas circulation pump and a low-temperature gas heater are arranged on the air supply pipeline in sequence; a total circulation pipeline and a preheating circulation pipeline arranged in parallel are connected between the end and the head end of the air supply pipeline, a preheating circulation valve is arranged on the preheating circulation pipeline, a shaping ventilation pipeline, a high-temperature ventilation pipeline and a low-temperature ventilation pipeline arranged in parallel are connected between the head end of the total circulation pipeline and the end of the air supply pipeline, a shaping cut-off valve group is arranged on the shaping ventilation pipeline, a high-temperature cut-off valve and a high-temperature gas heater are arranged on the high-temperature ventilation pipeline, a low-temperature cut-off valve is arranged on the low-temperature ventilation pipeline, and a total circulation cut-off valve is arranged at the end of the total circulation pipeline. The invention can achieve better temperature and pressure control, reduce energy waste, and is conducive to improving vulcanization quality.

Description

Technical Field

[0001] The invention relates to the technical field of bladder vulcanizing machines, and in particular to a self-circulating nitrogen heating system and a heating method for a vulcanizing machine. Background Art

[0002] The bladder vulcanizer uses the molding method to manufacture tires. During the vulcanization process, the bladder is heated by a heating medium, and the outer mold is heated by electric heating. In traditional bladder vulcanizers, the bladder is heated by high-temperature steam heated by a boiler. Because the pressure and temperature of the heating medium need to be adjusted at different times during the entire bladder vulcanization process, and the pressure and especially the temperature control of high-temperature steam are difficult to adapt to this adjustment, later only the initial preheating of the bladder was carried out by steam, and during normal bladder vulcanization operations, electrically heated nitrogen was used for self-circulation heating. However, this heating method still has the following problems. First, a boiler is usually used with multiple vulcanizers. Even if only one vulcanizer is in production, the boiler must be turned on, and the boiler energy consumption is serious. Second, the temperature of electrically heated nitrogen drops seriously after heat exchange, and its temperature control is also difficult to adapt to the temperature adjustment at different times, and even the temperature required for vulcanization in the bladder cannot be reached, resulting in defects in the final tire vulcanization quality. Third, steam and nitrogen use the same pipeline to pass through the capsule vulcanizer. During the vulcanization production process, liquid water produced by steam will inevitably be mixed into the nitrogen, which will cause the nitrogen to be impure, and in turn make it more difficult to control the heating temperature and pressure of the nitrogen when it is heated alone. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a self-circulating nitrogen heating system and a heating method for a vulcanizing machine which can achieve better temperature and pressure control, reduce energy waste, and improve vulcanization quality.

[0004] In order to solve the above technical problems, the technical solution of the present invention is: a self-circulating nitrogen heating system for a vulcanizer comprises an air supply pipeline, wherein the air supply pipeline is connected with a low-pressure air intake device and a high-pressure air intake device; a radiator, a gas circulation pump and a low-temperature gas heater are sequentially arranged on the air supply pipeline; a total circulation pipeline and a preheating circulation pipeline arranged in parallel are connected between the end and the head end of the air supply pipeline, and a capsule arrangement of the vulcanizer is connected to the total circulation pipeline; a preheating circulation valve is arranged on the preheating circulation pipeline, and a shaped ventilation pipeline, a high-temperature ventilation pipeline and a low-temperature ventilation pipeline arranged in parallel are connected between the head end of the total circulation pipeline and the end of the air supply pipeline, a shaped ventilation pipeline is provided with a shaped cut-off valve group, a high-temperature cut-off valve and a high-temperature gas heater are provided on the high-temperature ventilation pipeline, a low-temperature cut-off valve is provided on the low-temperature ventilation pipeline, and a total circulation cut-off valve is provided at the end of the total circulation pipeline.

[0005] As a preferred technical solution, a nitrogen recovery pipeline is provided on the total circulation pipeline between the total circulation cut-off valve and the capsule, and a nitrogen recovery valve is provided on the nitrogen recovery pipeline.

[0006] As a preferred technical solution, a nitrogen exhaust pipeline is provided on the total circulation pipeline between the total circulation cut-off valve and the capsule, and a capsule exhaust valve is provided on the nitrogen exhaust pipeline.

[0007] As a preferred technical solution, a vacuum pipeline is provided on the total circulation pipeline between the total circulation cut-off valve and the capsule, and a vacuum valve is provided on the vacuum pipeline.

[0008] As a preferred technical solution, a vulcanization temperature sensor is provided on the total circulation pipeline before the capsule air intake.

[0009] As a preferred technical solution, a return air temperature sensor is provided between the air supply pipeline and the total circulation pipeline and the preheating circulation pipeline.

[0010] As a preferred technical solution, the low-pressure air intake device includes a low-pressure nitrogen air intake pipeline connected to the air supply pipeline, and a low-pressure nitrogen air intake valve and a low-pressure nitrogen air filter valve are provided on the low-pressure nitrogen air intake pipeline.

[0011] As a preferred technical solution, the high-pressure air intake device includes a high-pressure nitrogen air intake pipeline connected to the air supply pipeline, and a high-pressure nitrogen air intake valve and a high-pressure nitrogen air filter valve are provided on the high-pressure nitrogen air intake pipeline.

[0012] The heating method of the self-circulating nitrogen heating system of the vulcanizing machine comprises the following steps:

[0013] Step 1: The low-pressure air intake device supplies low-pressure nitrogen to the air supply pipeline, the preheating circulation valve is opened, the low-temperature gas heater and the gas circulation pump are operated, and the radiator is not operated; the low-pressure nitrogen circulates between the air supply pipeline and the preheating circulation pipeline, and is gradually preheated to a low-temperature temperature;

[0014] Step 2: close the preheating circulation valve, open the shaping cut-off valve group and the total circulation cut-off valve, keep the low-temperature gas heater and the gas circulation pump working, and keep the radiator inoperative; low-pressure and low-temperature nitrogen enters the capsule to perform capsule pre-shaping;

[0015] Step 3: close the stereotyped cut-off valve group, open the high-temperature cut-off valve, the high-temperature gas heater works, the low-temperature gas heater and the gas circulation pump keep working, and the radiator keeps not working; when the low-pressure and low-temperature nitrogen passes through the high-temperature ventilation pipeline, the high-temperature gas heater raises the temperature again to form low-pressure and high-temperature nitrogen, and the low-pressure and high-temperature nitrogen enters the capsule to provide heat for the vulcanization operation, and the nitrogen is self-circulated between the gas supply pipeline, the high-temperature ventilation pipeline and the total circulation pipeline to maintain the high temperature of the vulcanization operation at the capsule;

[0016] Step 4: close the high-temperature shut-off valve, stop the high-temperature gas heater, open the low-temperature shut-off valve, the high-pressure air intake device supplies high-pressure nitrogen to the air supply pipeline, the low-temperature gas heater and the gas circulation pump keep working, and the radiator starts working; the high-pressure nitrogen is heated by the low-temperature gas heater to form high-pressure low-temperature nitrogen, and the high-pressure low-temperature nitrogen enters the capsule for cooling and shape preservation. The high-pressure nitrogen passing through the capsule is first cooled by the radiator, and then heated to the low-temperature temperature by the low-temperature gas heater and recirculated; the temperature at the capsule gradually decreases and is finally maintained at the low-temperature temperature level of the nitrogen;

[0017] Step 5: Stop the low-temperature gas heater, the gas circulation pump and the radiator, and discharge the nitrogen in the gas supply pipeline, the total circulation pipeline and the low-temperature ventilation pipeline.

[0018] As a preferred technical solution, the method of external exhaust treatment in step five includes high-pressure nitrogen recovery and residual nitrogen discharge.

[0019] By adopting the above technical solution, the present invention achieves the following beneficial effects:

[0020] (1) By selectively inputting low-pressure nitrogen and high-pressure nitrogen into the pipeline, the nitrogen pressure can be adjusted at different times of vulcanization to achieve better pressure control;

[0021] (2) Before supplying air into the capsule, circulating heating is performed in the closed-loop pipeline of the air supply pipeline and the preheating circulation pipeline, which can reduce heat loss and ensure a higher preheating rate. The closed-loop pipeline has a simple structure and is easy to match one machine. Therefore, the use of boiler steam can be abandoned in the preheating stage of the vulcanizer, and it is not affected by the number of vulcanizers opened, so that energy is used more reasonably and energy waste is reduced.

[0022] (3) Two-stage heating is used in the positive vulcanization stage. Nitrogen has a good temperature raising effect and is more likely to form the high temperature required for vulcanization. The first stage of heating uses a low-temperature gas heater that originally preheats nitrogen, which can simultaneously achieve the effect of simplifying the system pipeline design and improving temperature controllability;

[0023] (4) During the over-vulcanization stage, high-pressure nitrogen is used for low-temperature heating, and the heat is dissipated by the radiator, so that the bladder gradually gets rid of the high-temperature environment. This can reduce the burning phenomenon of the tire during the over-vulcanization stage, ensure the quality of the tire, and at the same time reduce energy consumption and achieve energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The following drawings are intended only to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0025] Figure 1 It is a schematic diagram of an embodiment of the present invention.

[0026] In the figure: 1-air supply pipeline; 11-low-pressure air intake device; 12-high-pressure air intake device; 13-radiator; 14-gas circulation pump; 15-low-temperature gas heater; 2-total circulation pipeline; 21-nitrogen recovery pipeline; 22-nitrogen recovery valve; 23-nitrogen exhaust pipeline; 24-capsule exhaust valve; 25-vacuum pipeline; 26-vacuum valve; 27-vulcanization temperature sensor; 28-return air temperature sensor; 29-total circulation cut-off valve; 3-molding ventilation pipeline; 31-molding cut-off valve group; 32-molding front cut-off valve; 33-molding pressure-stabilizing valve; 34-molding rear cut-off valve; 4-high-temperature ventilation pipeline; 41-high-temperature cut-off valve; 42-high-temperature gas heater; 5-low-temperature ventilation pipeline; 51-low-temperature cut-off valve; 6-preheating circulation pipeline; 61-preheating circulation valve; 7-capsule; 8-central mechanism; 81-central ventilation pipeline. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with the accompanying drawings and examples. In the following detailed description, exemplary embodiments of the present invention are described only by way of illustration. Needless to say, those of ordinary skill in the art will recognize that the described embodiments may be modified in a variety of ways without departing from the spirit and scope of the present invention. Therefore, the drawings and description are illustrative in nature and are not intended to limit the scope of protection of the claims.

[0028] like Figure 1 As shown, the self-circulating nitrogen heating system of the vulcanizer includes an air supply pipeline 1, and the air supply pipeline 1 is connected with a low-pressure air intake device 11 and a high-pressure air intake device 12. The low-pressure air intake device 11 is used to supply low-pressure nitrogen to the air supply pipeline 1, and the high-pressure air intake device 12 is used to supply high-pressure nitrogen to the air supply pipeline 1. In this embodiment, the nitrogen pressure is adjusted at different vulcanization time periods by selectively inputting low-pressure nitrogen and high-pressure nitrogen, so as to achieve better pressure control.

[0029] The low-pressure air intake device 11 of this embodiment includes a low-pressure nitrogen air intake pipeline connected to the air supply pipeline 1, and a low-pressure nitrogen air intake valve and a low-pressure nitrogen air filter valve are provided on the low-pressure nitrogen air intake pipeline. The high-pressure air intake device 12 includes a high-pressure nitrogen air intake pipeline connected to the air supply pipeline 1, and a high-pressure nitrogen air intake valve and a high-pressure nitrogen air filter valve are provided on the high-pressure nitrogen air intake pipeline.

[0030] The gas supply pipeline 1 is provided with a radiator 13, a gas circulation pump 14 and a low-temperature gas heater 15 in sequence. The sequential arrangement should be understood as being arranged in sequence according to the flow direction of nitrogen. Among them, the radiator 13 described in this embodiment generally refers to a heat dissipation box structure that has a heat dissipation pipeline through which nitrogen can pass, and can dissipate heat from the heat dissipation pipeline by means of air cooling or water cooling. When air cooling or water cooling is not performed, the heat loss of the heat dissipation pipeline is relatively limited. The gas circulation pump 14 is used to provide nitrogen self-circulation power, and its structural principle is a well-known technology that can be known to those skilled in the art, and will not be repeated here. The low-temperature gas heater 15 is used to heat nitrogen to a cryogenic temperature, and it is usually an electric coil heating structure.

[0031] A total circulation pipeline 2 and a preheating circulation pipeline 6 arranged in parallel are connected between the end and the head end of the air supply pipeline 1, and a capsule 7 of a vulcanizing machine is connected to the total circulation pipeline 2. In this way, the air supply pipeline 1 can form a closed-loop circulation pipeline of nitrogen with the preheating circulation pipeline 6 and the total circulation pipeline 2 respectively. A preheating circulation valve 61 is provided on the preheating circulation pipeline 6. When the preheating circulation valve 61 is opened, nitrogen can form a closed-loop circulation between the air supply pipeline 1 and the preheating circulation pipeline 6. Among them, the head end and the end of the pipeline involved in this embodiment are both the end where nitrogen enters the pipeline as the head end, and the end where nitrogen leaves the pipeline as the end.

[0032] A shaped ventilation pipeline 3, a high-temperature ventilation pipeline 4 and a low-temperature ventilation pipeline 5 arranged in parallel are connected between the head end of the total circulation pipeline 2 and the end of the air supply pipeline 1. The shaped ventilation pipeline 3 is provided with a shaped cut-off valve group 31, the high-temperature ventilation pipeline 4 is provided with a high-temperature cut-off valve 41 and a high-temperature gas heater 42, the low-temperature ventilation pipeline 5 is provided with a low-temperature cut-off valve 51, and the end of the total circulation pipeline 2 is provided with a total circulation cut-off valve 29. Three parallel pipelines are arranged between the total circulation pipeline 2 and the air supply pipeline 1, and the nitrogen can be selected through which pipeline to enter the capsule 7 according to the pressure and temperature requirements of the nitrogen in different vulcanization periods. Therefore, this embodiment uses a relatively simple pipeline design to achieve flexible control of the temperature and pressure at the capsule 7. Among them, the shaped cut-off valve group 31 includes a shaped pre-cut-off valve 32, a shaped pressure-stabilizing valve 33 and a shaped post-cut-off valve 34 arranged in sequence.

[0033] Preferably, a nitrogen recovery pipeline 21 is provided on the total circulation pipeline 2 between the total circulation shut-off valve 29 and the capsule 7, and a nitrogen recovery valve 22 is provided on the nitrogen recovery pipeline 21. When the vulcanization work is completed, the nitrogen recovery valve 22 can be opened to recover part of the nitrogen in the pipeline to reduce the waste of nitrogen resources.

[0034] Preferably, a nitrogen exhaust pipeline 23 is provided on the total circulation pipeline 2 between the total circulation cut-off valve 29 and the capsule 7, and a capsule exhaust valve 24 is provided on the nitrogen exhaust pipeline 23. When the vulcanization work is completed, the nitrogen filled in the capsule 7 can be discharged by opening the capsule exhaust valve 24.

[0035] Preferably, a vacuum line 25 is provided on the total circulation pipeline 2 between the total circulation shut-off valve 29 and the capsule 7, and a vacuum valve 26 is provided on the vacuum line 25. For a vulcanizer, its capsule 7 is usually equipped with a central mechanism 8 for use. After the vulcanization is completed, the capsule 7 needs to be exhausted, stretched and shrunk. This process requires the central mechanism 8 to be extended synchronously to facilitate the subsequent removal of the vulcanized tire and the placement of the next tire blank. In this embodiment, the vacuum valve 26 is provided, and the nitrogen in the capsule 7 can be forced to be discharged by vacuuming to facilitate its smooth stretching. Of course, the central mechanism 8 in this embodiment is also connected to a central ventilation line 81, so that the central mechanism 8 cooperates with the capsule 7 for stretching or shaping through air intake and exhaust.

[0036] Preferably, a vulcanization temperature sensor 27 is provided on the total circulation pipeline 2 before the air intake of the capsule 7 to detect the temperature of the nitrogen entering the capsule 7 in real time to ensure the normal temperature requirement of the vulcanization operation at the capsule 7. A return air temperature sensor 28 is provided between the air supply pipeline 1 and the total circulation pipeline 2 and the preheating circulation pipeline 6 to detect the temperature of the nitrogen after passing through the capsule 7 in real time, so as to facilitate the adjustment of the circulation speed, heat dissipation intensity, or heating intensity according to its temperature condition.

[0037] The heating method of the self-circulating nitrogen heating system of the vulcanizing machine comprises the following steps.

[0038] Step 1: The low-pressure air intake device 11 supplies low-pressure nitrogen to the air supply pipeline 1, the preheating circulation valve 61 is opened, the low-temperature gas heater 15 and the gas circulation pump 14 are working, and the radiator 13 is not working; the low-pressure nitrogen circulates between the air supply pipeline 1 and the preheating circulation pipeline 6, and is gradually preheated to a low temperature. The nitrogen is circulated and heated in the closed-loop pipeline of the air supply pipeline 1 and the preheating circulation pipeline 6, which can reduce heat loss and ensure a high preheating rate. The closed-loop pipeline has a simple structure and is easy to match one machine. Therefore, the use of boiler steam can be abandoned in the preheating stage of the vulcanizer, and it is not affected by the number of vulcanizers opened, so that energy is used more reasonably and energy waste is reduced.

[0039] Step 2: close the preheating circulation valve 61, open the shaping cut-off valve group 31 and the total circulation cut-off valve 29, keep the low-temperature gas heater 15 and the gas circulation pump 14 working, and keep the radiator 13 not working; low-pressure and low-temperature nitrogen enters the capsule 7 to pre-shape the capsule 7. This step is equivalent to the preheating stage of vulcanization. For the shaping cut-off valve group 31 of this embodiment, which adopts the pre-shaping cut-off valve 32, the shaping pressure-stabilizing valve 33 and the post-shaping cut-off valve 34, the nitrogen entering the capsule 7 can be supplied at a stable pressure, ensuring the smooth progress of the pre-shaping.

[0040] Step 3: close the fixed cut-off valve group 31, open the high-temperature cut-off valve 41, the high-temperature gas heater 42 works, the low-temperature gas heater 15 and the gas circulation pump 14 keep working, and the radiator 13 keeps not working; when the low-pressure and low-temperature nitrogen passes through the high-temperature ventilation pipeline 4, the high-temperature gas heater 42 raises the temperature again to form low-pressure and high-temperature nitrogen, and the low-pressure and high-temperature nitrogen enters the capsule 7 for heating the vulcanization operation, and the nitrogen self-circulates between the gas supply pipeline 1, the high-temperature ventilation pipeline 4 and the total circulation pipeline 2 to maintain the high temperature of the vulcanization operation at the capsule 7. This step is the positive vulcanization stage of the vulcanization process. This embodiment adopts two-stage heating, the nitrogen temperature raising effect is good, it is easier to form the high temperature required for vulcanization, and the high-temperature nitrogen forms a self-circulation in the closed-loop pipeline, which can also reduce heat loss; and the first-stage heating uses the low-temperature gas heater 15 that originally preheats the nitrogen, which can simultaneously achieve the effect of simplifying the system pipeline design and improving the temperature controllability.

[0041] Step 4: close the high-temperature shut-off valve 41, stop the high-temperature gas heater 42, open the low-temperature shut-off valve 51, the high-pressure air intake device 12 supplies high-pressure nitrogen to the gas supply pipeline 1, the low-temperature gas heater 15 and the gas circulation pump 14 keep working, and the radiator 13 starts working; the high-pressure nitrogen is heated by the low-temperature gas heater 15 to form high-pressure and low-temperature nitrogen, and the high-pressure and low-temperature nitrogen enters the capsule 7 for cooling and shape preservation. The high-pressure nitrogen passing through the capsule 7 is first dissipated and cooled by the radiator 13, and then heated to the low-temperature temperature by the low-temperature gas heater 15 and recirculated; the temperature at the capsule 7 gradually decreases and is finally maintained at the low-temperature level of the nitrogen.

[0042] This step is equivalent to the over-vulcanization stage of tire vulcanization. Under the condition of ensuring the vulcanization temperature, the capsule 7 can gradually get rid of the high temperature environment, thereby reducing the burning phenomenon of the tire during the over-vulcanization stage, ensuring the quality of the tire, and reducing energy consumption to achieve energy saving. In this step, high-pressure nitrogen is used instead of low-pressure nitrogen, which can get rid of the high-temperature environment at the capsule 7 without losing pressure, which is also conducive to ensuring the quality of tire shaping.

[0043] Step 5: Stop the low-temperature gas heater 15, the gas circulation pump 14 and the radiator 13, and discharge the nitrogen in the gas supply pipeline 1, the total circulation pipeline 2 and the low-temperature ventilation pipeline 5. Preferably, the method of external discharge in this step includes high-pressure nitrogen recovery and residual nitrogen discharge. For the present embodiment provided with a nitrogen recovery valve 22 and a capsule exhaust valve 24, the nitrogen recovery valve 22 is first opened to partially recover the high-pressure nitrogen; then the nitrogen recovery valve 22 is closed, and the capsule exhaust valve 24 is opened to directly discharge the nitrogen that cannot be recycled in the pipeline.

[0044] In addition, since the vacuum valve 26 is provided in this embodiment, this embodiment also includes step 6: opening the vacuum valve 26 to evacuate the capsule 7. Of course, at the same time, the central ventilation pipeline 81 supplies compressed air to cooperate with the evacuation of the capsule 7 to make the capsule 7 stretch and shrink.

[0045] This embodiment can coordinate ideal pressure and temperature at each stage of vulcanization in the vulcanizer through reasonable pipeline design and valve body control, which is conducive to ensuring the quality of vulcanization. In addition, each stage adopts nitrogen self-circulation mode to make reasonable use of energy, significantly reduce energy waste, and significantly improve efficiency.

[0046] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A heating method, characterized in that: The heating method uses a vulcanizer self-circulating nitrogen heating system; the vulcanizer self-circulating nitrogen heating system includes an air supply pipeline, the air supply pipeline is connected with a low-pressure air intake device and a high-pressure air intake device; a radiator, a gas circulation pump and a low-temperature gas heater are arranged in sequence on the air supply pipeline; a total circulation pipeline and a preheating circulation pipeline arranged in parallel are connected between the end and the head end of the air supply pipeline, the capsule of the vulcanizer is connected to the total circulation pipeline; a preheating circulation valve is arranged on the preheating circulation pipeline, and the total circulation pipeline is connected with the capsule of the vulcanizer; a preheating circulation valve is arranged on the preheating circulation pipeline, and the total circulation pipeline is connected with the capsule of the vulcanizer; a preheating circulation valve is arranged on the preheating circulation pipeline, and the preheating circulation valve is arranged on the preheating circulation pipeline. A shaped ventilation pipeline, a high-temperature ventilation pipeline and a low-temperature ventilation pipeline arranged in parallel are connected between the head end of the loop pipeline and the end of the gas supply pipeline. The shaped ventilation pipeline is provided with a shaped cut-off valve group, the high-temperature ventilation pipeline is provided with a high-temperature cut-off valve and a high-temperature gas heater, the low-temperature ventilation pipeline is provided with a low-temperature cut-off valve, and the end of the total circulation pipeline is provided with a total circulation cut-off valve; the head end and the end of the pipeline are both the end where nitrogen enters the pipeline as the head end, and the end where nitrogen leaves the pipeline as the end; The heating method comprises the following steps: Step 1: The low-pressure air intake device supplies low-pressure nitrogen to the air supply pipeline, the preheating circulation valve is opened, the low-temperature gas heater and the gas circulation pump are operated, and the radiator is not operated; the low-pressure nitrogen circulates between the air supply pipeline and the preheating circulation pipeline, and is gradually preheated to a low-temperature temperature; Step 2: close the preheating circulation valve, open the shaping cut-off valve group and the total circulation cut-off valve, keep the low-temperature gas heater and the gas circulation pump working, and keep the radiator inoperative; low-pressure and low-temperature nitrogen enters the capsule to perform capsule pre-shaping; Step 3: close the stereotyped cut-off valve group, open the high-temperature cut-off valve, the high-temperature gas heater works, the low-temperature gas heater and the gas circulation pump keep working, and the radiator keeps not working; when the low-pressure and low-temperature nitrogen passes through the high-temperature ventilation pipeline, the high-temperature gas heater raises the temperature again to form low-pressure and high-temperature nitrogen, and the low-pressure and high-temperature nitrogen enters the capsule to provide heat for the vulcanization operation, and the nitrogen is self-circulated between the gas supply pipeline, the high-temperature ventilation pipeline and the total circulation pipeline to maintain the high temperature of the vulcanization operation at the capsule; Step 4: close the high-temperature shut-off valve, stop the high-temperature gas heater, open the low-temperature shut-off valve, the high-pressure air intake device supplies high-pressure nitrogen to the air supply pipeline, the low-pressure air intake device stops supplying low-pressure nitrogen, the low-temperature gas heater and the gas circulation pump keep working, and the radiator starts working; the high-pressure nitrogen is heated by the low-temperature gas heater to form high-pressure low-temperature nitrogen, and the high-pressure low-temperature nitrogen enters the capsule for cooling and shape preservation. The high-pressure nitrogen passing through the capsule is first dissipated and cooled by the radiator, and then heated to the low-temperature temperature by the low-temperature gas heater and recirculated; the temperature at the capsule gradually decreases and is finally maintained at the low-temperature level of nitrogen; Step 5: Stop the low-temperature gas heater, the gas circulation pump and the radiator, and discharge the nitrogen in the gas supply pipeline, the total circulation pipeline and the low-temperature ventilation pipeline.

2. A heating method according to claim 1, characterized in that: A nitrogen recovery pipeline is provided on the total circulation pipeline between the total circulation cut-off valve and the capsule, and a nitrogen recovery valve is provided on the nitrogen recovery pipeline.

3. A heating method according to claim 1, characterized in that: A nitrogen exhaust pipeline is provided on the total circulation pipeline between the total circulation cut-off valve and the capsule, and a capsule exhaust valve is provided on the nitrogen exhaust pipeline.

4. A heating method according to claim 1, characterized in that: A vacuum pipeline is provided on the total circulation pipeline between the total circulation cut-off valve and the capsule, and a vacuum valve is provided on the vacuum pipeline.

5. A heating method according to claim 1, characterized in that: A vulcanization temperature sensor is provided on the total circulation pipeline before the air intake of the capsule.

6. A heating method according to claim 1, characterized in that: The low-pressure air intake device comprises a low-pressure nitrogen air intake pipeline connected to the air supply pipeline, and a low-pressure nitrogen air intake valve and a low-pressure nitrogen air filter valve are arranged on the low-pressure nitrogen air intake pipeline.

7. A heating method according to claim 1, characterized in that: The high-pressure air intake device comprises a high-pressure nitrogen air intake pipeline connected to the air supply pipeline, and a high-pressure nitrogen air intake valve and a high-pressure nitrogen filter valve are arranged on the high-pressure nitrogen air intake pipeline.

8. A heating method according to claim 1, characterized in that: The method of external exhaust treatment described in step five includes high-pressure nitrogen recovery and residual nitrogen discharge.

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