Sealing method of middle-high voltage electric heating tube

Abstract

The invention relates to the technical field of electric heating tube sealing, in particular to a sealing method for a middle-high voltage electric heating tube. In order to solve the technical problem that an existing sealing technology for the middle-high-voltage electric heating tube has defects, according to the sealing method for the middle-high-voltage electric heating tube, the prefabricated glue prefabricated blocks with the porosity being 0% are used, the pressure resistance certainty of a tube opening is guaranteed, the glue prefabricated blocks can be manufactured in advance in batches, solidification time is not needed, and the production efficiency is greatly improved; and in the sealing process, the first glue layer with the small thickness is arranged, so that curing is faster, the glue infiltration amount is smaller, and generated bubbles are fewer. In addition, gaps among the electric heating tube, the glue prefabricated block and the lead-out rod are sealed through the mixed glue layer, the side wall glue layer and the inner ring glue layer, and full sealing is achieved; and the thicknesses of the mixed glue layer, the side wall glue layer and the inner ring glue layer are relatively small, the curing time is short, and the production efficiency is also ensured.

Description

Technical Field

[0001] The invention relates to the technical field of electric heating pipe sealing, and in particular to a sealing method for medium- and high-voltage electric heating pipes. Background Art

[0002] Glue filling and sealing is a critical process for the production of medium and high voltage electric heating tubes (medium and high voltage generally refers to greater than or equal to 4kV), because the glue that solidifies after glue filling needs to be used as a sealant to isolate the entry of moisture in the air to avoid the insulation material in the metal tank from getting damp and reducing its pressure resistance; secondly, for medium and high voltage electric heating tubes, the glue itself needs to have a high insulation strength to prevent conduction between the exposed lead rod and the metal tube wall.

[0003] Some existing solutions use vulcanized rubber or soft silicone for sealing, and use its soft and deformable characteristics to fill the electric heating pipe mouth to achieve a sealing effect. However, this method is often used for electric heating pipes below the voltage level. When the voltage level is higher than 4kV, these materials themselves cannot achieve the required electrical strength.

[0004] There is also a plan to use epoxy resin glue for potting. The specific method is to take glue A (epoxy resin) and glue B (curing agent) respectively, mix them and pour them into the electric heating pipe mouth, forming a certain liquid level height on the surface of the insulating powder layer, and it can achieve a higher electrical strength after solidification; but because the AB glue is a liquid with high fluidity when it is just poured, and the insulating powder itself is a granular substance, there are air pores inside the powder layer, so the glue will penetrate into the insulating powder layer, and the air in the pores will float up to form bubbles, and finally form holes or pits on the surface after the glue solidifies.

[0005] For low-voltage electric heating tube products, the voltage resistance requirement is not high, so small pores or pits can be accepted. However, for medium and high voltage electric heating tubes, the requirements for the glue insulation thickness are more stringent. Pores or pits mean the lack of glue in that part, which will make its insulation strength unable to meet the performance requirements. Summary of the invention

[0006] In view of the technical problem that the existing sealing technology for medium and high voltage electric heating pipes has defects, the present invention provides a sealing method for medium and high voltage electric heating pipes, which ensures the pressure resistance certainty of the pipe mouth by using a prefabricated glue prefabricated block with a porosity of 0%, and the glue prefabricated blocks can be produced in batches in advance without the need for solidification time, thereby greatly improving the production efficiency; and, in the sealing process, a first glue layer with a smaller thickness is provided, so that the curing is faster, the glue seepage is less, and the generation of fewer bubbles is less; in addition, the gap between the electric heating pipe, the glue prefabricated block and the lead-out rod is sealed by a mixed glue layer, a side wall glue layer and an inner ring glue layer, so as to achieve full sealing; and the thickness of the mixed glue layer, the side wall glue layer and the inner ring glue layer is also smaller, and the curing time is short, which also ensures the production efficiency.

[0007] The technical solution provided by the present invention is: a sealing method for medium and high voltage electric heating pipes, comprising: making a glue prefabricated block: using a flat mold to make a glue prefabricated block with a porosity of 0%, a lead rod hole is arranged in the middle of the glue prefabricated block, and the thickness of the glue prefabricated block is 7-10mm; inserting a lead rod: filling insulating powder in the electric heating pipe to form an insulating powder layer, wrapping an insulating sheath at one end of the lead rod by a heat shrink process, inserting part of the lead rod into the insulating powder layer, and retaining a gap between the bottom end of the insulating sheath and the insulating powder layer; first glue pouring: pouring glue with a depth of 1-2mm on the surface of the insulating powder layer to form a first glue layer, wherein part of the glue infiltrates into the insulating powder layer to form a co-infiltration layer, waiting for 6-8h until the first glue layer is in a semi-cured state, and the co-infiltration layer gradually solidifies, and the bubbles formed in the process of the glue infiltrating into the insulating powder layer form pits on the surface of the first glue layer as the glue solidifies; putting in the glue prefabricated block; Block making: a 1-3mm thick annular semi-solidified glue layer is laid on the bottom surface of the glue prefabricated block, the glue prefabricated block is pressed into the nozzle of the electric heating tube, the lead-out rod passes through the lead-out rod hole, and sinks into the first glue layer at the bottom of the glue prefabricated block; in the process of the glue prefabricated block sinking into the first glue layer, the annular semi-solidified glue layer is used to gradually cover and fill the pits on the surface of the first glue layer, and the first glue layer and the annular semi-solidified glue layer are gradually mixed to form a mixed glue layer; extruding the glue prefabricated block: extruding the glue prefabricated block in the direction of the insulating powder layer until the thickness of the mixed glue layer is extruded to less than 2mm, and at the same time, part of the glue in the mixed glue layer overflows between the glue prefabricated block and the tube wall of the electric heating tube to form a side wall glue layer, and part of the glue overflows between the lead-out rod and the inner wall of the lead-out rod hole to form an inner ring glue layer; glue solidification molding: keep the position of the glue prefabricated block unchanged, wait for the glue to fully solidify, and complete the sealing.

[0008] Optionally, after the glue is solidified and formed, quick-drying glue is applied on the surface of the glue prefabricated block.

[0009] Optionally, a groove rod is fixedly provided on the inner wall of the electric heating tube, and a groove is provided on the edge of the glue prefabricated block, and the groove is matched with the groove rod.

[0010] Optionally, the groove rod is provided with a scale.

[0011] Optionally, the thickness of the side wall glue layer is 0.1-0.5 mm.

[0012] Optionally, the upper surface of the side wall glue layer is flush with the upper surface of the glue prefabricated block.

[0013] Optionally, the thickness of the inner ring glue layer is 0.1-0.5 mm.

[0014] Optionally, the upper surface of the inner ring glue layer is flush with the upper surface of the glue prefabricated block.

[0015] Optionally, while waiting for the glue to fully solidify and until the sealing is completed, hot air is used to blow the tube opening of the electric heating tube.

[0016] Optionally, the distance between the bottom end of the insulating sheath and the top opening of the electric heating tube is 15 to 20 mm.

[0017] The technical solution provided by the present invention has the following beneficial effects compared with the prior art: in view of the technical problem that the existing sealing technology for medium and high voltage electric heating pipes has defects, the sealing method for medium and high voltage electric heating pipes proposed by the present invention ensures the pressure resistance certainty of the pipe mouth by using a prefabricated glue prefabricated block with a porosity of 0%, and the glue prefabricated blocks can be produced in batches in advance without the need for solidification time, thereby greatly improving the production efficiency; and, in the sealing process, a first glue layer with a smaller thickness is provided, so that the curing is faster, the glue seepage is less, and fewer bubbles are generated; in addition, the gap between the electric heating pipe, the glue prefabricated block and the lead-out rod is sealed by a mixed glue layer, a side wall glue layer and an inner ring glue layer to achieve full sealing; and the thickness of the mixed glue layer, the side wall glue layer and the inner ring glue layer is also smaller, and the curing time is short, which also ensures the production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of the glue prefabricated block proposed in an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the process of inserting and extracting the rod according to an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the first glue filling process proposed in an embodiment of the present invention.

[0021] Figure 4 A schematic diagram of the process of placing a glue prefabricated block according to an embodiment of the present invention.

[0022] Figure 5 A schematic diagram of the process of extruding a glue prefabricated block according to an embodiment of the present invention.

[0023] Figure 6 This is a schematic diagram of the structure of the electric heating pipe orifice after the glue prefabricated block is extruded according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the accompanying drawings and embodiments.

[0025] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are only used to explain the relevant inventions, rather than to limit the invention. It should also be noted that, for the convenience of description, only the parts related to the invention are shown in the accompanying drawings. The words "first", "second", etc. described in the present invention are set for the convenience of describing the technical solution of the present invention, and have no specific limiting effect. They are all general references and do not constitute a limiting effect on the technical solution of the present invention. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a connection between the insides of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Multiple technical solutions in the same embodiment, and multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions without contradictions or conflicts, all of which are within the scope of protection required by the present invention.

[0026] This embodiment proposes a sealing method for a medium- and high-voltage electric heating pipe 11, comprising making a glue prefabricated block 10: the glue prefabricated block 10 is as shown in the attached Figure 1 As shown, a glue prefabricated block 10 with a porosity of 0% is made by using a flat mold. A guide rod hole 100 is provided in the middle of the glue prefabricated block 10. The thickness of the glue prefabricated block 10 is generally 7 to 10 mm to meet the insulation strength requirements of the medium and high voltage electric heating pipe 11.

[0027] For this embodiment, the process of making the glue prefabricated block 10 can be completed independently, that is, the glue prefabricated block 10 can be made in large quantities in advance in the factory. The material of the glue prefabricated block 10 is generally epoxy resin glue, and because a flat mold is used for industrial production, the glue prefabricated block 10 with a porosity of 0% can be achieved. It should be noted that the porosity of 0% here means that the porosity is less than the lower range value, and the porosity measurement form of the traditional glue filling and sealing method can be referred to. The glue prefabricated block 10 of this embodiment can fully meet the insulation strength requirements of the medium and high voltage electric heating pipe 11 (≥4kV) in engineering practice, and is regarded as having a porosity of 0%.

[0028] The sealing method of the medium and high voltage electric heating tube 11 also includes inserting the lead-out rod 14: Figure 2 As shown, insulating powder is filled in the electric heating tube 11 to form an insulating powder layer 12, an insulating sheath 13 is wrapped at one end of the lead-out rod 14 by a heat shrink process, and part of the lead-out rod 14 is inserted into the insulating powder layer 12, and a gap is retained between the bottom end of the insulating sheath 13 and the insulating powder layer 12.

[0029] The step of inserting the lead rod 14 is a preliminary preparation. The lead rod 14 extends from the insulating powder layer 12 of the electric heating tube 11 to the tube mouth for the final wiring. It is necessary to wrap a layer of insulating sheath 13 on the surface of this section of the lead rod 14 through a heat shrink process to ensure that no electrical conduction occurs between the lead rod 14 and the inner wall of the electric heating tube 11. However, since the insulating sheath 13 will shrink during the heat shrink process, as shown in the attached Figure 2 As shown, it can be seen that the bottom end of the insulating sheath 13 near the insulating powder layer 12 is still exposed to the air with a gap of about 1 mm. Preferably, the distance between the bottom end of the insulating sheath 13 and the top tube opening of the electric heating tube 11 is controlled to be 15-20 mm.

[0030] Therefore, the sealing method of this embodiment is used not only to isolate the insulating powder from the air, but also to fill the gap to ensure that the lead-out rod 14 does not break through the air to the wall of the electric heating tube 11 or any other position to conduct electricity. In the traditional glue filling and sealing technology, the thickness of the glue required for sealing here is required to be at least 6 to 8 mm thick to ensure sufficient withstand voltage insulation strength. In this embodiment, the glue prefabricated block 10 with a thickness of 7 to 10 mm directly replaces most of the glue.

[0031] In the traditional process, after the glue is poured into the nozzle of the electric heating tube 11, it is necessary to wait for the glue to gradually solidify and solidify in order to obtain the expected insulation strength and structural strength. The curing of glue is a process that starts from the surface and gradually spreads to the inner core. Under certain working conditions, the length of time it takes to solidify is positively correlated with the thickness of the glue. The thicker the glue is, the slower the curing time. Generally speaking, in the traditional process, it takes about 2 to 3 days for the 6-8 mm thick glue to be initially cured. At this time, the surface has been completely cured, while most of the internal glue has only been initially cured, and the innermost layer has not dried out. It takes about 7 days to completely cure. In the present embodiment, there is no need to pour in a large amount of glue. By making the glue prefabricated block 10 in advance, the curing waiting time can be greatly reduced.

[0032] In this embodiment, a groove rod 15 is additionally fixedly provided on the inner wall of the electric heating tube 11, and a groove 16 is provided on the edge of the glue prefabricated block 10. The matching arrangement of the groove 16 and the groove rod 15 can play a guiding role, ensuring that the glue prefabricated block 10 can move up and down along the groove rod 15 and remain stable, and can prevent the glue prefabricated block 10 from rotating.

[0033] And, in this embodiment, the groove rod 15 is provided with a scale, and one of the functions of the scale is to measure the position of the insulating powder layer 12 at the tube mouth of the electric heating tube 11 and the thickness of the glue layer.

[0034] After the lead rod 14 is inserted, the first glue filling can be carried out: Figure 3 As shown, glue with a depth of 1 to 2 mm is poured on the surface of the insulating powder layer 12 to form a first glue layer 201, wherein part of the glue seeps into the insulating powder layer 12 to form a co-infiltration layer 200, and 6 to 8 hours are waited until the first glue layer 201 is in a semi-cured state. At the same time, the co-infiltration layer 200 is gradually cured, and bubbles formed in the process of the glue infiltrating into the insulating powder layer 12 form pits on the surface of the first glue layer 201 as the glue solidifies.

[0035] During the first glue pouring process, the temperature of the glue poured into the nozzle is generally 30-40°C. The glue pouring thickness can be measured by the scale line on the slot rod 15, and the amount of the first glue pouring is controlled to be 1-2 mm thick so that it can cover the portion of the lead rod 14 that is not wrapped with the insulating sheath 13. Since the insulating powder constituting the insulating layer is a granular substance, there are air pores inside the insulating powder layer 12. Therefore, after the glue is poured in, it begins to slowly penetrate into the insulating powder layer 12, and synchronously, the air in the pores will float up to form bubbles. However, since the first glue layer 201 formed by the first glue pouring is relatively thin, after the bubbles are generated, the surface tension of the bubbles will break through the bondage of the glue and then burst, and will not be suppressed in the first glue layer 201. When solidified, the bubbles will form pits on the surface of the first glue layer 201.

[0036] In contrast, in the existing process, 6 to 8 mm of glue is injected at one time. The surface tension of the bubbles will be restrained due to the deep liquid level and high pressure. After solidification, the bubbles will remain inside the glue and become pores.

[0037] In addition, since a thin layer of glue cures faster than a thick layer of glue and contains less glue, the depth of the glue penetration is shallower, so that the bubbles that come up are relatively less. The structural layer formed by the combination of the glue penetration and the insulating powder is called the co-infiltration layer 200. After the first glue layer 201 solidifies, the co-infiltration layer 200 is a relatively solid mixture solid, so it has the function of fixing the surface of the insulating powder layer 12 to prevent the insulating powder layer 12 from loosening in subsequent processes.

[0038] After about 6 to 8 hours, the glue constituting the first glue layer 201 has become viscous, that is, in a semi-cured state. At this time, due to its high viscosity, the glue will no longer continue to penetrate into the insulating powder layer 12.

[0039] At this time, the glue prefabricated block 10 can be put in, and the operation is as follows: Figure 4 As shown, a ring-shaped semi-solidified glue layer 202 with a thickness of 1 to 3 mm is laid on the bottom surface of the glue prefabricated block 10, the glue prefabricated block 10 is pressed into the pipe mouth of the electric heating tube 11, and the lead-out rod 14 passes through the lead-in rod hole 100 until the bottom of the glue prefabricated block 10 sinks into the first glue layer 201.

[0040] The annular semi-solidified glue layer 202 conforms to the shape of the glue prefabricated block 10, and the center of the ring needs to provide an escape space for the lead-out rod 14. In the process of the glue prefabricated block 10 sinking into the first glue layer 201, the annular semi-solidified glue layer 202 is used to gradually cover and fill the pits on the surface of the first glue layer 201, and the first glue layer 201 and the annular semi-solidified glue layer 202 are gradually mixed to form a mixed glue layer 203.

[0041] In this operation, a layer of semi-solidified glue is applied on the bottom surface of the glue prefabricated block 10 to form an annular semi-solidified glue layer 202, which is required to surround the middle guide rod hole 100 to form an arc-shaped protrusion toward the ground. The formation of this shape is formed by the tension of the glue itself and the action of gravity. Since the semi-solidified glue has a certain plasticity, this shape can also be formed by a mold or other artificial methods. During the process of slowly pressing down the glue prefabricated block 10, when the annular semi-solidified glue layer 202 just contacts the first glue layer 201, the middle protrusion contacts the first glue layer 201 first, and then gradually combines with the surroundings when squeezed, such as Figure 4 The middle arrow points to the direction in which the air is discharged when filling the pits. This can ensure that the air can be squeezed out smoothly to the surroundings to avoid the pits being trapped in the glue and becoming closed bubbles, thereby ensuring the pressure-resistant yield rate.

[0042] Subsequently, it is necessary to continue extruding the glue preform block 10: extrude the glue preform block 10 toward the insulating powder layer 12 until the thickness of the mixed glue layer 203 is extruded to less than 2 mm. At the same time, part of the glue in the mixed glue layer 203 overflows to between the glue preform block 10 and the tube wall of the electric heating tube 11 to form a side wall glue layer 204, and part of the glue overflows to between the lead-out rod 14 and the inner wall of the lead-out rod hole 100 to form an inner ring glue layer 205.

[0043] As attached Figure 5 and attached Figure 6 As shown, due to the extrusion of the glue prefabricated block 10, the glue in the mixed glue layer 203 is squeezed from a thickness of about 2 mm to a thinner thickness of about 1 mm, and the remaining glue is squeezed to the side wall, forming a thin side wall glue layer 204 around the glue prefabricated block 10, and a thin inner ring glue layer 205 around the lead rod 14. This is because the outer diameter of the glue prefabricated block 10 is smaller than the inner diameter of the electric heating tube 11, and the diameter of the lead rod hole 100 of the glue prefabricated block 10 is larger than the diameter of the lead rod 14. Generally speaking, the thickness of the side wall glue layer 204 and the inner ring glue layer 205 should be controlled at 0.1-0.5 mm.

[0044] It is conceivable that, in combination with the above-mentioned embodiment, scale lines are provided on the groove rod 15 , and the pressing depth of the glue prefabricated block 10 can be determined by the scale lines. At the same time, the horizontality of the glue prefabricated block 10 can be ensured by comparing multiple scale lines.

[0045] The height of the side wall glue layer 204 and the inner ring glue layer 205 generally needs to be squeezed to be close to the upper surface of the glue prefabricated block 10, for example, to be flush with the upper surface of the glue prefabricated block 10, thereby ensuring the depth without overflowing.

[0046] Then, you can wait for the glue to solidify and take shape: you need to keep the position of the glue prefabricated block 10 unchanged, and wait for the glue to fully solidify until the sealing is completed.

[0047] At this time, since the mixed glue layer 203 is further thinned to 1mm, the side wall glue layer 204 and the inner ring glue layer 205 are also controlled within a thickness range of less than 1mm, such as the aforementioned 0.1-0.5mm, the curing speed of the glue will be greatly accelerated, and it will be completely cured in about 3-4 days. Compared with the existing process that requires seven days for the 6-8mm glue layer to cure, the waiting time for curing in this embodiment can be shortened by half, which is equivalent to doubling the production efficiency.

[0048] In addition, while waiting for the glue to fully cure and until the sealing is completed, hot air can be used to blow the nozzle of the electric heating tube 11 to speed up the curing speed. Since industrial production is batch production, a large number of electric heating tubes 11 can be arranged together. At this time, hot air at about 70°C can be used to blow horizontally at the nozzle of the electric heating tube 11. Since the tube wall of the electric heating tube 11 is made of metal, it can be easily purged and heated. At the same time, since the thickness of each glue layer is small and close to the inner side of the tube wall, it can be efficiently heated to about 40-50°C by heat transfer. At this temperature, the glue can undergo a curing reaction faster and is not easy to deteriorate. Under the above conditions, the curing time of the glue can be further reduced from 3-4 days to 2-3 days. Therefore, the entire glue filling and sealing period is shortened by 1 working day again.

[0049] Furthermore, after the glue is solidified, a layer of anti-oxidation or anti-acid corrosion quick-drying glue can be applied on the surface of the glue prefabricated block 10. It does not need to provide pressure resistance, but can be used as a secondary seal to enhance air tightness and protect the internal glue from oxidation and corrosion.

[0050] The materials of the glue prefabricated block 10, glue and quick-drying glue involved in this embodiment can all be epoxy resins, and the glue selection in the existing glue filling and sealing process of the electric heating tube 11 can be referred to.

[0051] The sealing method for the medium and high voltage electric heating tube 11 proposed in this embodiment involves a mixed glue layer 203 composed of an annular semi-solidified glue layer 202 and a first glue layer 201, and a side wall glue layer 204 and an inner ring glue layer 205 formed by the mixed glue layer 203 overflowing under pressure. The function of these structures (referred to as "glue layers") is as follows: since the glue prefabricated block 10 is a solid material, if it is directly placed at the nozzle of the electric heating tube 11, it will not be able to achieve a tight fit with the insulating powder layer 12, and the glue prefabricated block 10 and the metal inner wall cannot be absolutely flat, that is, there must be a small gap, so the existence of these glue layers ensures the fit and sealing of the glue prefabricated block 10 in contact with each surface.

[0052] The functions of the glue prefabricated block 10 are: 1. The glue prefabricated block 10 with a porosity of 0% is used to fill most of the space at the pipe mouth to ensure the most basic insulation distance; 2. It can be prepared in advance, saving the long curing time of the glue in the electric heating tube 11 and speeding up the construction period of the glue filling and sealing process.

[0053] Compared with the existing glue filling and sealing technology of the electric heating tube 11, the beneficial effects of this embodiment include:

[0054] 1. Regarding the process of filling the surface of the insulating powder layer 12 with glue at a depth of 1 to 2 mm to form the first glue layer 201, the following beneficial effects can be achieved: (1) The thinner first glue layer 201 makes it easier for bubbles to burst, rather than trapping them in a thicker glue layer, forming pores that are difficult to fill. (2) The total amount of glue with a smaller thickness is less, and it cures faster. In addition, since less glue seeps into the surface, fewer bubbles are generated. (3) The first glue layer 201 that is preferentially set can seal the surface of the insulating powder layer 12 to prevent the insulating powder from flying and floating, thereby affecting the working environment. At the same time, the co-infiltration layer 200 can also fix the surface powder layer to prevent it from loosening during subsequent operations.

[0055] 2. The use of the glue prefabricated block 10 has the following beneficial effects: (1) The glue prefabricated block 10 has a porosity of 0%, which provides a basic insulation safety distance and ensures the pressure resistance of the pipe mouth. (2) The glue prefabricated block 10 can be produced in large quantities with higher efficiency. (3) Preparing the glue prefabricated block 10 in advance is equivalent to pre-curing the glue, which greatly reduces the curing waiting time of the glue in the electric heating tube 11. The amount of glue added later is also very small, and the curing time is short. The combination of the two greatly reduces the duration of the glue filling and sealing process of the electric heating tube 11, thereby improving production efficiency.

[0056] 3. Regarding the application of a 1-3mm thick annular semi-solidified glue layer 202 on the bottom surface of the glue prefabricated block 10, the beneficial effects are as follows: (1) The physical properties of having a certain viscosity, not continuing to seep, and being deformable can be used to fill the pits at the bonding interface, and the convex arc shape formed by its natural droop can fully discharge the gas on the surface of the first glue layer 201, avoiding the formation of closed bubbles at the bonding interface, and ensuring the voltage resistance yield. (2) The glue prefabricated block 10 is made of the same material as the glue in the traditional process, so that it can form a higher bonding strength with each glue layer, and the glue material itself has high insulation, thereby ensuring a voltage resistance yield of more than 4kV. (3) The first glue layer 201 and the annular semi-solidified glue layer 202 are gradually mixed to form a mixed glue layer 203. Part of the glue in the mixed glue layer 203 overflows to form a side wall glue layer 204 and an inner ring glue layer 205. These glue layers will act as sealing fillers between the glue prefabricated block 10 and the pipe mouth to ensure the tightness of the pipe mouth.

[0057] The present invention and its embodiments are described schematically above, which is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by it and creatively designs a structure and an embodiment similar to the technical solution without departing from the purpose of the invention, they shall all fall within the protection scope of the present invention.

Claims

1. A sealing method for a medium- and high-voltage electric heating tube (11), characterized in that: include: Making a glue prefabricated block (10): using a flattened mold to make a glue prefabricated block (10) with a porosity of 0%, a guide rod hole (100) being provided in the middle of the glue prefabricated block (10), and a thickness of the glue prefabricated block (10) being 7 to 10 mm; Inserting the lead-out rod (14): filling the electric heating tube (11) with insulating powder to form an insulating powder layer (12), wrapping an insulating sheath (13) at one end of the lead-out rod (14) by a heat shrink process, and inserting part of the lead-out rod (14) into the insulating powder layer (12), with a gap being retained between the bottom end of the insulating sheath (13) and the insulating powder layer (12); First glue pouring: pouring glue with a depth of 1 to 2 mm on the surface of the insulating powder layer (12) to form a first glue layer (201), wherein part of the glue seeps into the insulating powder layer (12) to form a co-infiltration layer (200), waiting for 6 to 8 hours until the first glue layer (201) is in a semi-cured state, and the co-infiltration layer (200) gradually solidifies, and bubbles formed in the process of the glue seeping into the insulating powder layer (12) form pits on the surface of the first glue layer (201) as the glue solidifies; Inserting the glue prefabricated block (10): laying a ring-shaped semi-solidified glue layer (202) with a thickness of 1 to 3 mm on the bottom surface of the glue prefabricated block (10), pressing the glue prefabricated block (10) into the pipe mouth of the electric heating tube (11), and passing the lead rod (14) through the lead rod hole (100) until the bottom of the glue prefabricated block (10) sinks into the first glue layer (201); In the process of the glue prefabricated block (10) sinking into the first glue layer (201), the annular semi-solidified glue layer (202) is used to gradually cover and fill the pits on the surface of the first glue layer (201), and the first glue layer (201) and the annular semi-solidified glue layer (202) are gradually mixed to form a mixed glue layer (203); Extruding the glue prefabricated block (10): extruding the glue prefabricated block (10) in the direction of the insulating powder layer (12) until the thickness of the mixed glue layer (203) is extruded to less than 2 mm, and at the same time, part of the glue in the mixed glue layer (203) overflows to between the glue prefabricated block (10) and the tube wall of the electric heating tube (11) to form a side wall glue layer (204), and part of the glue overflows to between the lead-out rod (14) and the inner wall of the lead-out rod hole (100) to form an inner ring glue layer (205); Glue solidification and molding: keep the glue prefabricated block (10) in place and wait for the glue to fully solidify until the sealing is completed.

2. A sealing method for a medium- and high-voltage electric heating pipe (11) according to claim 1, characterized in that: After the glue is solidified and formed, quick-drying glue is applied on the surface of the glue prefabricated block (10).

3. A sealing method for a medium- and high-voltage electric heating pipe (11) according to claim 1, characterized in that: A groove rod (15) is fixedly arranged on the inner wall of the electric heating tube (11), and a groove (16) is arranged on the edge of the glue prefabricated block (10), and the groove (16) is matched with the groove rod (15).

4. A sealing method for a medium- and high-voltage electric heating pipe (11) according to claim 3, characterized in that: The groove rod (15) is provided with scales.

5. A sealing method for a medium- and high-voltage electric heating pipe (11) according to claim 1, characterized in that: The thickness of the side wall glue layer (204) is 0.1-0.5 mm.

6. A sealing method for a medium- and high-voltage electric heating pipe (11) according to claim 5, characterized in that: The upper surface of the side wall glue layer (204) is flush with the upper surface of the glue prefabricated block (10).

7. A sealing method for a medium- and high-voltage electric heating pipe (11) according to claim 1 or 5, characterized in that: The thickness of the inner ring glue layer (205) is 0.1-0.5 mm.

8. A sealing method for a medium- and high-voltage electric heating pipe (11) according to claim 7, characterized in that: The upper surface of the inner ring glue layer (205) is flush with the upper surface of the glue prefabricated block (10).

9. A sealing method for a medium- and high-voltage electric heating pipe (11) according to claim 1, characterized in that: While waiting for the glue to fully solidify and until the sealing is completed, hot air is used to blow the pipe opening of the electric heating pipe (11).

10. A sealing method for a medium- and high-voltage electric heating pipe (11) according to claim 1, characterized in that: The distance between the bottom end of the insulating sheath (13) and the top pipe opening of the electric heating pipe (11) is 15 to 20 mm.

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