Sealing method for medium-high voltage electric heating tube

Abstract

The present application relates to the technical field of electric heating tube sealing technology, and particularly relates to a sealing method of a medium-high voltage electric heating tube. In view of the technical problem of defects existing in the sealing technology of the medium-high voltage electric heating tube, the sealing method of the medium-high voltage electric heating tube, by using a pre-prepared glue preform block with a porosity of 0%, guarantees the pressure resistance certainty of the pipe opening, and the glue preform block can be prepared in batches in advance, without solidification time, greatly improving the production efficiency. In the sealing process, a first glue layer with a small thickness is arranged, so that the solidification is faster, the glue infiltration amount is less, and the air bubbles are less. In addition, the gap between the electric heating tube, the glue preform block and the lead-out rod is closed by the mixed glue layer, the side wall glue layer and the inner ring glue layer, so that sufficient sealing is achieved. The thickness of the mixed glue layer, the side wall glue layer and the inner ring glue layer is also small, the solidification time is short, and the production efficiency is also guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sealing of electric heating tube, in particular to a sealing method of medium and high voltage electric heating tube. BACKGROUND

[0002] Glue sealing is a key process for the production and manufacture of medium and high voltage electric heating tube (medium and high voltage generally refers to greater than or equal to 4kV), because the glue solidified after glue sealing needs to isolate the water vapor in the air from entering, so as to avoid the moisture resistance of the insulation material in the metal tank from being reduced; secondly, for medium and high voltage electric heating tube, the glue itself needs to have high insulation strength to prevent the electric conduction between the exposed lead rod and the metal tube wall.

[0003] In the existing scheme, part of the sealing is carried out by using vulcanized rubber or soft silicone, which can achieve the sealing effect by filling the electric heating tube port with the deformable soft state of the material, but this method is commonly used for electric heating tubes below the voltage level, and when the voltage level is higher than 4kV, the material itself cannot meet the required electrical strength;

[0004] There is also a scheme for sealing by using epoxy resin glue, which specifically comprises taking A glue (epoxy resin) and B glue (curing agent), mixing them and then pouring them into the electric heating tube port to form a certain liquid level on the surface of the insulation powder layer, so as to achieve high electrical strength after solidification; but since the AB glue is a liquid with high flowability when it is just poured, and the insulation powder is a granular material with air voids in the powder layer, the glue will sink into the insulation powder layer, and the air in the voids 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 requirement for voltage resistance is not high, so small air holes or pits can be accepted, but for medium and high voltage electric heating tube, the requirement for the insulation thickness of the glue is relatively strict, and air holes or pits mean the absence of glue at that part, which will make the insulation strength unable to meet the performance requirements. SUMMARY

[0006] In view of the technical problems of the existing sealing technology of medium and high voltage electric heating tube, the present application provides a sealing method of medium and high voltage electric heating tube, which uses a pre-prepared glue preform with a gas hole rate of 0% to ensure the voltage resistance certainty of the tube port, and the glue preform can be made in batches in advance without solidification time, greatly improving the production efficiency; and in the sealing process, a first glue layer with small thickness is set to make the solidification faster, the glue sinkage smaller and the air bubbles fewer; in addition, the gap between the electric heating tube, the glue preform and the lead rod is closed by the mixed glue layer, the side wall glue layer and the 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 small, the solidification time is short, and the production efficiency is also ensured.

[0007] The technical scheme provided by the application is a sealing method for a medium-high voltage electric heating tube, comprising: preparing a glue preform: using a flat mold to prepare a glue preform with a porosity of 0%, the glue preform being provided with a lead rod hole in the middle part, and the thickness of the glue preform being 7-10 mm; inserting a lead rod: filling the electric heating tube with insulating powder to form an insulating powder layer, wrapping an insulating sheath on one end of the lead rod through a heat shrink process, and inserting part of the lead rod into the insulating powder layer, with a gap being reserved between the bottom end of the insulating sheath and the insulating powder layer; first glue filling: filling glue with a depth of 1-2 mm on the surface of the insulating powder layer to form a first glue layer, part of the glue infiltrating into the insulating powder layer to form a co-infiltration layer, waiting for 6-8 h until the first glue layer is in a semi-cured state, and the co-infiltration layer gradually solidifies, with air bubbles formed in the process of glue infiltration into the insulating powder layer forming pits on the surface of the first glue layer; placing the glue preform: laying an annular semi-cured glue layer with a thickness of 1-3 mm on the bottom surface of the glue preform, and pressing the glue preform into the tube opening of the electric heating tube, with the lead rod passing through the lead rod hole and sinking into the first glue layer at the bottom of the glue preform; in the process of sinking the glue preform into the first glue layer, the annular semi-cured glue layer gradually covers and fills the pits on the surface of the first glue layer, and the first glue layer and the annular semi-cured glue layer gradually mix to form a mixed glue layer; extruding the glue preform: extruding the glue preform towards the insulating powder layer until the thickness of the mixed glue layer is extruded to less than 2 mm, at the same time, part of the glue in the mixed glue layer overflows between the glue preform 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 rod and the inner wall of the lead rod hole to form an inner ring glue layer; glue solidification and molding: keeping the position of the glue preform unchanged, and waiting for the glue to fully solidify until the sealing is completed.

[0008] Optionally, after the glue solidification and molding, a quick-drying glue is laid on the surface of the glue preform.

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

[0010] Optionally, a scale is arranged on the groove rod.

[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 preform.

[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 preform.

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

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

[0017] Compared with the prior art, the technical scheme provided by the present application has the following beneficial effects: for the technical problem of defects existing in the prior art sealing technology of the middle and high voltage electric heating tube, the sealing method of the middle and high voltage electric heating tube provided by the present application uses the prefabricated glue prefabricated block with a porosity of 0%, which guarantees the pressure resistance certainty of the pipe opening, and the glue prefabricated block can be made in batches in advance, without solidification time, greatly improving the production efficiency; and during the sealing process, the first glue layer with small thickness is set, so that the solidification is faster, the glue infiltration amount is less, and the air bubbles are less; in addition, the gap between the electric heating tube, the glue prefabricated block and the lead-out rod is closed by the mixed glue layer, the side wall glue layer and the inner ring glue layer, so that the sealing is realized; and the thickness of the mixed glue layer, the side wall glue layer and the inner ring glue layer is also small, the solidification time is short, and the production efficiency is also guaranteed. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The structure diagram of the glue prefabricated block provided by the embodiment of the present application.

[0019] Figure 2 The process diagram of inserting the lead-out rod provided by the embodiment of the present application.

[0020] Figure 3 The process diagram of the first glue pouring provided by the embodiment of the present application.

[0021] Figure 4 The process diagram of putting the glue prefabricated block provided by the embodiment of the present application.

[0022] Figure 5 The process diagram of extruding the glue prefabricated block provided by the embodiment of the present application.

[0023] Figure 6 The structure diagram of the pipe opening of the electric heating tube after extruding the glue prefabricated block provided by the embodiment of the present application. DETAILED DESCRIPTION

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

[0025] The application will be described in further detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, and not to limit the application. In addition, it should be noted that only parts related to the application are shown in the drawings for ease of description. The first, second, and the like in the application are set for the convenience of describing the technical solutions of the application, and have no specific limiting effect, and are all generic. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. In the description of the application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. Unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements inside. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances. The technical solutions in the same embodiment and the technical solutions in different embodiments can be arranged and combined to form new technical solutions that do not exist contradictions or conflicts, which are within the scope of the application.

[0026] The embodiment provides a sealing method of a medium-high voltage electric heating tube 11, which comprises preparing a glue preform 10. As shown in the drawings, Figure 1 The glue preform 10 is prepared by using a flat mold to prepare the glue preform 10 with a porosity of 0%. The glue preform 10 is provided with a rod guide hole 100 in the middle part. The thickness of the glue preform 10 is generally 7-10 mm, so as to meet the insulation strength requirement of the medium-high voltage electric heating tube 11.

[0027] For this embodiment, the process of making the glue preform 10 can be done independently, that is, the glue preform 10 can be made in advance in large quantities in the factory. The material of the glue preform 10 is generally epoxy resin glue, and because it is made industrially using a flat mold, a glue preform 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 a lower range value. Referring to the porosity measurement form of the traditional glue filling sealing method, the glue preform 10 of the present embodiment can fully meet the insulation strength requirements of the medium and high voltage heating tube 11 (≥4kV) in engineering practice, and is regarded as having a porosity of 0%.

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

[0029] The step of inserting the lead-out rod 14 is a preliminary preparation work. The lead-out rod 14 extends out of the pipe opening from the insulation powder layer 12 of the heating tube 11, which is used for the final wiring. An insulation sheath 13 needs to be wrapped on the surface of this part of the lead-out rod 14 by heat shrinkage process, which aims to ensure that the lead-out rod 14 does not conduct electricity with the inner wall of the heating tube 11. However, the insulation sheath 13 will shrink during the heat shrinkage process, as shown in FIG. 3, it can be seen that there is still about 1mm gap exposed to the air near the bottom end of the insulation sheath 13 close to the insulation powder layer 12. Preferably, the distance between the bottom end of the insulation sheath 13 and the top pipe opening of the heating tube 11 is controlled to be 15-20mm. Figure 2

[0030] Therefore, the sealing method of the present embodiment not only serves to isolate the insulation powder from the air, but also serves to fill and block the gap, so as to ensure that the lead-out rod 14 does not conduct electricity by air breakdown to the heating tube 11 pipe wall or any other position. In the traditional glue filling sealing technology, the thickness of the glue required to be filled here needs to reach at least 6-8mm thick to ensure sufficient pressure resistance insulation strength. In the present embodiment, the 7-10mm thick glue preform 10 directly replaces most of the glue.

[0031] ​​In traditional processes, after the glue is poured into the inlet of the heating element 11, it must be allowed to gradually solidify to achieve the desired insulation and structural strength. The glue curing process begins with surface drying and gradually diffuses into the core. Under certain operating conditions, the curing time is directly proportional to the glue thickness; the thicker the glue layer, the slower the curing time. Typically, in traditional processes, a 6-8mm thick layer of glue requires approximately 2-3 days for initial curing. At this point, the surface is completely cured, while most of the glue inside is only partially cured, with the innermost layer not yet fully dried. Complete curing takes approximately 7 days. However, in this embodiment, it is unnecessary to pour in a large amount of glue. By prefabricating glue pre-formed blocks 10, the curing time can be significantly reduced.

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

[0033] In addition, in this embodiment, the groove bar 15 is provided with a scale. One of the functions of the scale line is to measure the position of the insulating powder layer 12 at the opening of the heating tube 11 and the thickness of the adhesive layer.

[0034] After inserting the lead-out rod 14, the first potting can be performed: as shown in the attached document. Figure 3 As shown, a 1-2 mm deep adhesive is potted onto the surface of the insulating powder layer 12 to form a first adhesive layer 201. Part of the adhesive seeps into the insulating powder layer 12 to form a co-permeation layer 200. After waiting for 6-8 hours until the first adhesive layer 201 is in a semi-cured state, the co-permeation layer 200 gradually cures. Air bubbles formed during the process of the adhesive seeping into the insulating powder layer 12 form pits on the surface of the first adhesive layer 201 as the adhesive cures.

[0035] During the first glue application, the glue temperature at the injection nozzle is generally 30-40℃. The glue thickness can be measured by the scale lines on the groove rod 15, controlling the amount of glue applied in the first application to be 1-2 mm thick, so that it can cover the part of the lead rod 14 that is not covered with the insulating sheath 13. Since the insulating powder that makes up the insulating layers is itself a granular material, the insulating powder layer 12 has air pores inside. Therefore, after the glue is injected, it begins to slowly seep into the insulating powder layer 12. At the same time, the air in the pores rises and forms bubbles. However, since the first glue layer 201 formed by the first glue application is relatively thin, after the bubbles are formed, the surface tension of the bubbles will break through the binding of the glue and break them, instead of being suppressed in the first glue layer 201. When it solidifies, the bubbles will form pits on the surface of the first glue layer 201.

[0036] In contrast, in existing processes, when 6-8mm of glue is poured in at once, the surface tension of the air bubbles is constrained due to the depth of the liquid and the high pressure. After solidification, the air bubbles remain inside the glue and become pores.

[0037] Furthermore, because thin-layer adhesive cures faster and uses less adhesive, its penetration depth is shallower, resulting in fewer air bubbles rising to the surface. The structural layer formed by the adhesive penetration and bonding with the insulating powder is called the co-permeation layer 200. After the first adhesive layer 201 solidifies, the co-permeation layer 200 is a relatively strong solid mixture, thus serving to fix the surface of the insulating powder layer 12 and prevent it from loosening in subsequent processes.

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

[0039] At this point, the glue precast block 10 can be placed in, and the procedure is as follows: (see attached diagram) Figure 4 As shown, a layer of annular semi-solidified adhesive 202 with a thickness of 1 to 3 mm is applied to the bottom surface of the adhesive preform 10. The adhesive preform 10 is pressed into the opening of the heating tube 11, and the lead rod 14 passes through the lead rod hole 100 until the bottom of the adhesive preform 10 sinks into the first adhesive layer 201.

[0040] The annular semi-solid adhesive layer 202 conforms to the shape of the adhesive preform 10. The center of the annulus needs to provide clearance for the lead-out rod 14. As the adhesive preform 10 sinks into the first adhesive layer 201, the annular semi-solid adhesive layer 202 gradually covers and fills the pits on the surface of the first adhesive layer 201, and the first adhesive layer 201 and the annular semi-solid adhesive layer 202 gradually mix to form a mixed adhesive layer 203.

[0041] In this operation, a layer of semi-solidified adhesive is applied to the bottom surface of the pre-formed adhesive block 10 to form an annular semi-solidified adhesive layer 202. This layer is required to form an arc-shaped protrusion towards the ground around the central guide rod hole 100. This shape is formed by the tension and gravity of the adhesive itself. Furthermore, due to the plasticity of the semi-solidified adhesive, this shape can also be formed using molds or other artificial methods. During the slow pressing of the pre-formed adhesive block 10, when the annular semi-solidified adhesive layer 202 first contacts the first adhesive layer 201, the central protrusion initially contacts the first adhesive layer 201, and then gradually bonds outwards under pressure. Figure 4 The middle arrow points in this direction, ensuring that the air expelled when filling the dent can be smoothly squeezed out to the surrounding area, preventing the dent from becoming trapped in the glue and forming closed air bubbles, thus ensuring a high yield rate of pressure-resistant products.

[0042] Subsequently, the glue preform 10 needs to be further pressed: the glue preform 10 is pressed towards the insulating powder layer 12 until the thickness of the mixed glue layer 203 is pressed to less than 2mm, at the same time, part of the glue in the mixed glue layer 203 overflows between the glue preform 10 and the tube wall of the electric heating tube 11 to form the side wall glue layer 204, and part of the glue overflows between the lead-out rod 14 and the inner wall of the lead-out hole 100 to form the inner ring glue layer 205.

[0043] As shown in the accompanying drawings Figure 5 and the accompanying drawings Figure 6 As shown in the accompanying drawings, due to the pressing of the glue preform 10, the glue in the mixed glue layer 203 is pressed from about 2mm thick to about 1mm thick, and the remaining glue is pressed to the side wall to form a thin side wall glue layer 204 around the glue preform 10 and a thin inner ring glue layer 205 around the lead-out rod 14. This is because the outer diameter of the glue preform 10 is smaller than the inner diameter of the electric heating tube 11, and the diameter of the lead-out hole 100 of the glue preform 10 is larger than the diameter of the lead-out rod 14. Generally, the thickness of the side wall glue layer 204 and the inner ring glue layer 205 should be controlled within 0.1-0.5mm.

[0044] It is conceivable that, in combination with the aforementioned embodiment of setting scale lines on the slot rod 15, the pressing depth of the glue preform 10 can be determined by the scale lines, and the horizontality of the glue preform 10 can also 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 pressed close to the upper surface of the glue preform 10, such as reaching the same level as the upper surface of the glue preform 10, so as to ensure the depth and prevent overflow.

[0046] Subsequently, the glue can be allowed to solidify and form: the position of the glue preform 10 needs to be kept unchanged, and the glue needs to be allowed to 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, for example, about 0.1-0.5mm as mentioned above, so the solidification speed of the glue will be greatly accelerated, and after about 3-4 days, complete solidification can be completed. Compared with the 6-8mm glue layer in the existing process which needs seven days to solidify, the waiting time for solidification in this embodiment can be shortened by half, which is equivalent to doubling the production efficiency.

[0048] In addition, during the process of waiting for the glue to solidify completely until the sealing is completed, hot air can be used to blow the pipe opening of the electric heating tube 11 to speed up the solidification. Since industrial production is batch production, a large number of electric heating tubes 11 can be arranged together, at which time hot air at about 70°C can be blown horizontally against the pipe opening of the electric heating tube 11. Since the pipe wall of the electric heating tube 11 is of metal material, it can be easily blown and heated. At the same time, since the thickness of each glue layer is small and close to the inner side of the pipe wall, it can be efficiently heated to about 40-50°C. At this temperature, the glue can quickly solidify and is not prone to deterioration. Under the above conditions, the solidification time of the glue can be further reduced from 3-4 days to 2-3 days, so the entire glue filling and sealing period is shortened by one working day again.

[0049] Further, after the glue is solidified and shaped, a layer of quick-drying glue that is resistant to oxidation or acid corrosion can be applied on the surface of the glue preform 10. The quick-drying glue does not need to provide pressure resistance, but can serve as a secondary seal to strengthen air tightness and play a protective role against oxidation and corrosion of the internal glue.

[0050] The materials of the glue preform 10, the glue, and the quick-drying glue involved in the present embodiment can all be epoxy resins, which can be selected according to the existing glue filling and sealing process for the electric heating tube 11.

[0051] For the sealing method of the medium-high voltage electric heating tube 11 proposed in the present embodiment, the mixed glue layer 203 is composed of the annular semi-solidified glue layer 202 and the first glue layer 201, and the side wall glue layer 204 and the inner ring glue layer 205 are formed by the overflow of the mixed glue layer 203 under pressure. The functions of these structures (referred to as "glue layers" for short) are as follows: Since the glue preform 10 is a solid substance, if it is directly placed on the pipe opening of the electric heating tube 11, it cannot be tightly attached to the insulating powder layer 12. Moreover, the glue preform 10 cannot be absolutely flat with the metal inner wall, so there must be small gaps. Therefore, the existence of these glue layers ensures the tight sealing of the glue preform 10 with each surface.

[0052] The functions of the glue preform 10 are as follows: 1. The glue preform 10 with a porosity of 0% is used to fill most of the space in the pipe opening, thereby ensuring the basic insulation distance; 2. The glue preform 10 can be prepared in advance, thereby saving the long solidification time of the glue in the electric heating tube 11 and speeding up the glue filling and sealing process.

[0053] Compared with the existing glue filling and sealing technology for the electric heating tube 11, the present embodiment has the following beneficial effects:

[0054] 1. The beneficial effects of filling the surface of the insulating powder layer 12 with adhesive with a depth of 1-2 mm to form the first adhesive layer 201 are as follows: (1) The thinner first adhesive layer 201 makes it easier for air bubbles to burst, and unlike a thicker adhesive layer, it does not cause air bubbles to be trapped inside, forming pores that are difficult to fill. (2) The thinner adhesive layer has a smaller total amount of adhesive, cures faster, and produces fewer air bubbles due to less adhesive seepage. (3) The first adhesive layer 201, which is set in a preferred position, can seal the surface of the insulating powder layer 12, preventing the insulating powder from flying and floating, thereby affecting the working environment. At the same time, the co-permeation layer 200 can also fix the surface powder layer and prevent it from loosening in subsequent operations.

[0055] 2. Regarding the use of the pre-made adhesive block 10, the beneficial effects are as follows: (1) Utilizing the characteristic of the pre-made adhesive block 10 having a porosity of 0%, it provides a basic insulation safety distance, ensuring the pressure resistance of the pipe opening. (2) The pre-made adhesive block 10 can be mass-produced, resulting in higher efficiency. (3) Pre-preparing the pre-made adhesive block 10 is equivalent to pre-curing the adhesive, which greatly reduces the curing waiting time of the adhesive in the heating tube 11. The amount of adhesive added subsequently is also very small, and the curing time is short. The combination of the two greatly reduces the construction period of the glue filling and sealing process of the heating tube 11, and improves production efficiency.

[0056] 3. The beneficial effects of applying a 1-3 mm thick annular semi-solidified adhesive layer 202 to the bottom surface of the adhesive precast block 10 are as follows: (1) Utilizing the physical properties of certain viscosity, non-seepage, and deformability, it can fill the pits at the bonding interface, and the naturally drooping raised arc shape can fully expel the gas on the surface of the first adhesive layer 201, avoiding the formation of closed air bubbles at the bonding interface and ensuring the yield rate of pressure-resistant products. (2) The adhesive precast block 10 is made of the same material as the adhesive in the traditional process, which enables it to form a high bonding strength with each adhesive layer, and the adhesive material itself has high insulation, thereby ensuring the yield rate of products with a pressure resistance of over 4kV. (3) The first adhesive layer 201 and the annular semi-solidified adhesive layer 202 gradually mix to form a mixed adhesive layer 203. Some of the adhesive in the mixed adhesive layer 203 overflows to form a side wall adhesive layer 204 and an inner ring adhesive layer 205. These adhesive layers will act as a sealing filler between the adhesive preform 10 and the pipe opening to ensure the pipe opening fits tightly.

[0057] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method of sealing a medium-high voltage electrothermal tube (11), characterized in that, The application relates to a method for manufacturing a glue preform (10) of an electric heating tube (11). The method comprises the following steps: manufacturing the glue preform (10) by using a flat mold to manufacture the glue preform (10) with a porosity of 0%, and arranging a lead rod hole (100) in the middle of the glue preform (10), wherein the thickness of the glue preform (10) is 7-10 mm; inserting the lead rod (14) by filling the insulating powder into the electric heating tube (11) to form an insulating powder layer (12), wrapping the insulating sheath (13) on one end of the lead rod (14) by using a heat shrink process, inserting part of the lead rod (14) into the insulating powder layer (12), and reserving a gap between the bottom end of the insulating sheath (13) and the insulating powder layer (12); firstly pouring the glue by pouring the glue with a pouring depth of 1-2 mm on the surface of the insulating powder layer (12) to form a first glue layer (201), wherein part of the glue infiltrates into the insulating powder layer (12) to form a co-infiltration layer (200), waiting for 6-8 h until the first glue layer (201) is in a semi-cured state, and the co-infiltration layer (200) is gradually cured, and the 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) along with the curing of the glue; placing the glue preform (10) by arranging an annular semi-cured glue layer (202) with a thickness of 1-3 mm on the bottom surface of the glue preform (10), and pressing the glue preform (10) into the pipe opening of the electric heating tube (11), and the lead rod (14) passes through the lead rod hole (100) and sinks into the first glue layer (201) at the bottom of the glue preform (10); in the process of sinking the glue preform (10) into the first glue layer (201), the annular semi-cured glue layer (202) gradually covers and fills the pits on the surface of the first glue layer (201), and the first glue layer (201) and the annular semi-cured glue layer (202) gradually mix to form a mixed glue layer (203); extruding the glue preform (10) by extruding the glue preform (10) towards the insulating powder layer (12) until the thickness of the mixed glue layer (203) is extruded to be less than 2 mm, and meanwhile, part of the glue in the mixed glue layer (203) overflows between the glue preform (10) and the pipe wall of the electric heating tube (11) to form a side wall glue layer (204), and part of the glue overflows between the lead rod (14) and the inner wall of the lead rod hole (100) to form an inner ring glue layer (205); 2. A method of sealing a medium-high voltage electrothermal tube (11) according to claim 1, characterized in that, glue solidification molding by keeping the position of the glue preform (10) unchanged and waiting for the glue to be fully cured until the sealing is completed.

3. A method of sealing a medium-high voltage electrothermal tube (11) according to claim 1, characterized in that, After the glue solidification molding, quick-drying glue is arranged on the surface of the glue preform (10).

4. A method of sealing a medium-high voltage electrothermal tube (11) according to claim 3, characterized in that, The inner wall of the electric heating tube (11) is fixedly provided with a groove rod (15), and the edge of the glue preform (10) is provided with a groove (16), and the groove (16) is matched with the groove rod (15).

5. A method of sealing a medium-high voltage electrothermal tube (11) according to claim 1, characterized in that, The groove rod (15) is provided with a scale.

6. A method of sealing a medium-high voltage electrothermal tube (11) according to claim 5, characterized in that, The thickness of the side wall glue layer (204) is 0.1-0.5 mm.

7. A method of sealing a medium-high voltage electrothermal tube (11) according to claim 1 or 5, characterized in that, The upper surface of the side wall glue layer (204) is flush with the upper surface of the glue preform (10). The thickness of the inner ring glue layer (205) is 0.1-0.5 mm.

8. A method of sealing a medium-high voltage electrothermal tube (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 preform (10).

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

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

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