Casting method for ultrahigh-voltage cable conductor joint

Abstract

The invention discloses an ultrahigh-voltage cable conductor joint casting method, which comprises the following steps of: taking two sections of cables to be welded, reserving conductor core wires at the ends to be welded on the two sections of cables, obliquely cutting the welding ends of the conductor core wires, taking a quartz tube, connecting a quartz funnel to the upper end of the middle part of the quartz tube, inserting the welding ends of the two sections of conductor core wires into the quartz tube from the two ends of the quartz tube respectively, abutting against each other to form a V-shaped groove, pouring welding metal liquid into the quartz funnel until the V-shaped groove is filled with the welding metal liquid to be saturated, heating, fusing the conductor core wires and the welding metal liquid, carrying out water cooling on the surface of the quartz tube, and cracking the quartz tube after complete cooling and shaping, so as to obtain a finished product. And the welded conductor core wire is polished, and the outer layer of the conductor core wire is repaired, so that welding is completed. According to the casting method for the conductor joint of the ultrahigh-voltage cable, the connection quality of the ultrahigh-voltage cable is high, the operation difficulty is low, and the connection quality is stable.

Description

Technical Field

[0001] The invention relates to the field of cables, in particular to a casting method for an ultra-high voltage cable conductor joint. Background Art

[0002] With the rapid development of my country's economy, the social goal of universal electricity has been achieved, and electricity supply is still guaranteed in some remote areas. In the process of long-distance power supply, it is necessary to lay long-distance ultra-high voltage cables, but due to the limitations of ultra-high voltage cable production and transportation, the length of ultra-high voltage cables is limited, and it is difficult to achieve the goal of laying a single ultra-high voltage cable throughout the entire process, so ultra-high voltage cables need to be connected; and in the process of using ultra-high voltage cables, high voltage breakdown, environmental damage and other factors are prone to cause cable damage, so cable repair operations are required, and the damaged area of ​​the ultra-high voltage cable is cut off before connection.

[0003] The traditional method of connecting ultra-high voltage cables is to place two sections of ultra-high voltage cables opposite to each other and then fix them by argon arc welding, oxygen acetylene welding or explosion welding. However, these welding methods have the following disadvantages: 1. Because the conductor core wire is made of multiple metal conductor wires twisted together, there are many gaps between the metal conductor wires, which easily produces a large number of pores during the welding process; 2. During the welding process, the temperatures of several welding methods are relatively high, which can easily cause overheating of the conductor and severe annealing of the metal conductor wire, and can also easily damage the semiconductor tape and insulation layer of the ultra-high voltage cable; 3. In explosive welding, due to the limitation of welding rods, cat's eyes are easily formed during welding, and welding impurities are easily mixed into the welding joints; at the same time, it is difficult for welding rods to meet the electrical and mechanical properties of ultra-high voltage cable conductors; 4. Several welding methods have high operating requirements. The operator's operating level will directly affect the quality of welding. At the same time, the stable performance of welding is difficult to guarantee and fluctuates greatly. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for casting an ultra-high voltage cable conductor joint which has high ultra-high voltage cable connection quality, low operation difficulty and stable connection quality.

[0005] The technical solution adopted by the present invention to solve the above problem is a method for casting an ultra-high voltage cable conductor joint, comprising the following steps: S1: Take two sections of cables to be welded, cut off the outer structure of the conductor core wire on one end of the two sections of cables to be welded, and only keep the conductor core wire; S2: The welding end of the conductor core wire is cut obliquely, and a V-shaped groove is formed when the welding ends of two sections of the conductor core wire are against each other; S3: Take a quartz tube with a diameter equal to the diameter of the conductor core wire, and connect a quartz funnel to the upper middle end of the quartz tube; S4: inserting the welding ends of the two conductor core wires into the quartz tube from both ends of the quartz tube respectively, the welding ends of the two conductor core wires abut against each other to form a V-shaped groove, and the V-shaped groove is arranged below the quartz funnel; S5: molten welding metal; S6: preheating the quartz tube and quartz funnel; S7: pour the welding metal liquid into the quartz funnel until the welding metal liquid fills the V-shaped groove saturated; S8: Raise the temperature, heat the quartz tube and the quartz funnel, and melt the conductor core wire at the welding end, so that the conductor core wire and the welding metal liquid are fused; S9: When the conductor core wire and the welding metal liquid are completely fused, stop heating; S10: Cooling the surface of the quartz tube with water; S11: After the conductor core wire and the welding metal liquid are completely cooled and shaped, the quartz tube is broken; S12: Grinding the welded conductor core wire; S13: Repair the outer layer of the conductor core wire; S14: Cable welding is completed.

[0006] Compared with the prior art, the advantages of the present invention are: the welding method of the present invention uses a quartz tube as a connection mold, the structure finally formed by the welding method is stable, and has nothing to do with the operation level of the operator. It only needs to ensure the integrity of the operation to ensure the welding quality, thereby ensuring the connection quality of the cable; In steps S2-S4, it is ensured that the welding metal liquid can flow smoothly into the quartz tube, and the welding metal liquid can be fully contacted with the metal conductor wires in the conductor core wires at both ends, so that each metal conductor wire is connected. At the same time, the welding end of the conductor core wire is cut obliquely to ensure that each metal conductor wire can be melted, thereby ensuring the connection quality. If a planar structure is adopted, the metal conductor wires in the central area are less heated, and the melting condition will be significantly lower than that of the metal conductor wires in the outer circle. In step S5, the welding molten metal can be directly welded with the same material as the metal conductor wire, or a modifier can be added to the welding molten metal to increase the electrical performance and mechanical function of the welding point, thereby ensuring the welding quality and even enhancing the molding quality of the cable at the welding point to avoid repeated damage at this point; In step S6, the fluidity of the welding metal liquid in the quartz funnel and the quartz tube can be ensured to avoid premature solidification and affect the welding quality; In steps S7-S10, the welding operation of the two conductor core wires is completed; In step S11, the quartz tube is separated. First, the price of the quartz tube is relatively low, and it can be used as a disposable mold. There is no need to worry about the reuse of the quartz tube. At the same time, the traditional split mold is prone to form a joint seam at the joint. During the heating process, the joint seam is prone to deformation, which is not conducive to high-quality molding of casting welding. In addition, there are many processes and it is relatively complicated, which affects the welding efficiency. The quartz tube is used as the mold because the melting point of the quartz tube is higher than that of the conventional metal conductor wire. The quartz tube will not be deformed while the conventional metal conductor wire is melted. At the same time, the quartz tube is a transparent tube, which makes it easy to observe the molten connection state inside the quartz tube, better control the melting time, and ensure the welding quality.

[0007] As an improvement of the present invention, the conductor core wire material is copper, the welding metal liquid raw material is red copper, in step S6, the preheating temperature is 1000~1100℃, in step S8, the heating temperature is 1200~1300℃, through the improvement, the melting point of the quartz tube is 1713℃, the softening temperature is 1630℃, the melting point of copper is 1083℃, the preheating temperature is to ensure the fluidity of the welding metal liquid in the quartz funnel and the quartz tube, the heating temperature is to ensure the molten mixed connection of the welding metal liquid and the conductor core wire, and the temperature is limited to avoid severe annealing of the conductor core wire.

[0008] As an improvement of the present invention, the conductor core wire material is aluminum, and the welding metal liquid raw material is a conductive aluminum alloy. In step S6, the preheating temperature is 600~700℃, and in step S8, the heating temperature is 1200~1300℃. Through the improvement, the melting point of the quartz tube is 1713℃, the softening temperature is 1630℃, and the melting point of aluminum is 660℃. The preheating temperature is to ensure the fluidity of the welding metal liquid in the quartz funnel and the quartz tube, and the heating temperature is to ensure the molten mixed connection of the welding metal liquid and the conductor core wire. At the same time, the temperature is limited to avoid severe annealing of the conductor core wire.

[0009] As an improvement of the present invention, step S7 also includes step S7.1: performing mud sealing on the gaps between the quartz tube and the conductor core wires at both ends of the quartz tube. Through the improvement, when the quartz tube is sleeved on the conductor core wire, there is a size deviation between the tube diameter of the quartz tube and the wire diameter of the conductor core wire, and the conductor core wire is formed by twisting metal conductor wires, so that a gap is easily formed between the quartz tube and the conductor core wire. The gap at the end is sealed by mud sealing, while the gap between the metal conductor wires does not need to be sealed. The gap is smaller after twisting, and the gap is longer. The welding metal liquid is not easy to penetrate from the gaps between the metal conductor wires. The mud seal is not only easy to obtain, cheap or even free of charge, but also has high sealing effectiveness. After the welding of the conductor core wire is completed, the mud seal can be dried and cleaned, and it is not easy to have residues, which will not affect the use quality of the conductor core wire. It is the best material for short-term sealing with the conductor core wire.

[0010] As an improvement of the present invention, step S7 further includes step S7.2: the welding metal liquid has overflow in the quartz funnel. Through the improvement, the fullness of the welding metal liquid filling is ensured.

[0011] As an improvement of the present invention, step S7 also includes step S7.3: using the resonance of a tuning fork to reciprocate around the outside of the quartz tube until no bubbles are generated. Through the improvement, bubbles in the welding molten metal are eliminated to ensure the welding quality. At the same time, the overflowing welding molten metal in the quartz funnel can fill the space of the bubbles.

[0012] As an improvement of the present invention, step S8 also includes step S8.1: using a tuning fork resonance to reciprocate around the outside of the quartz tube until no bubbles are generated. Through the improvement, bubbles formed in the gaps between the original metal conductor wires in the molten state are eliminated to ensure the welding quality. At the same time, the overflowing welding metal liquid in the quartz funnel can fill the space of the bubbles.

[0013] As an improvement of the present invention, after completing step S9, the method further includes step S9.1: heating the mud seal until the mud seal is dried and cracked, and cleaning the mud seal. Through the improvement, the mud seal can be removed.

[0014] As an improvement of the present invention, the length of the quartz tube is not less than eight times the diameter of the conductor core wire. Through the improvement, during the melting process, only the welding end needs to be melted, but the connection stability of the quartz tube still needs to be ensured, and the connection between the quartz tube and the non-melting section of the conductor core wire needs to be fixed, so the length of the quartz tube needs to be longer.

[0015] As an improvement of the present invention, a water-cooling tube for cooling the quartz tube and the conductor core wire is wound around the connection between the end of the quartz tube and the conductor core wire. Through the improvement, when the welding metal liquid or the molten metal conductor wire moves toward the end of the quartz tube, it can solidify in time, and can also block the diffusion of heat, limiting the heat to the welding area, avoiding a large range of heating of the metal conductor wire, causing damage to the semiconductor strip and the insulation layer of the cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall cross-sectional structure when the welding metal liquid is injected into the quartz tube of the present invention.

[0017] Figure 2 It is a schematic diagram of the overall cross-sectional structure of the welding end of the molten conductor core wire of the present invention.

[0018] Figure 3 It is a schematic diagram of the conductor core wire welding forming structure of the present invention.

[0019] Figure 4 It is a schematic diagram of the enlarged structure of the connection between the quartz tube and the quartz funnel of the present invention.

[0020] As shown in the figure: 1. cable, 1.1. conductor core wire, 2. V-groove, 3. quartz tube, 3.1. exhaust slope, 4. quartz funnel, 5. mud seal, 6. electromagnetic heater, 7. tuning fork, 8. water cooling tube. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0022] like Figure 1-3 As shown, a method for casting an ultra-high voltage cable conductor joint comprises the following steps: S1: Take two sections of cable 1 to be welded, cut off the outer structure of the conductor core wire 1.1 on one end of the two sections of cable 1 to be welded, and only keep the conductor core wire 1.1; S2: The welding end of the conductor core wire 1.1 is cut obliquely, and when the welding ends of two sections of the conductor core wire 1.1 are butted against each other, a V-shaped groove 2 is formed; S3: Take a quartz tube with a diameter equal to the diameter of the conductor core wire 1.1, and a quartz funnel 4 is connected to the upper middle end of the quartz tube; S4: insert the welding ends of the two conductor core wires 1.1 into the quartz tube 3 from both ends of the quartz tube 3, respectively, the welding ends of the two conductor core wires 1.1 abut against each other to form a V-shaped groove 2, and the V-shaped groove 2 is arranged below the quartz funnel 4; S5: molten welding metal; S6: preheating the quartz tube 3 and the quartz funnel 4; S7: pouring the welding metal liquid into the quartz funnel 4 until the welding metal liquid fills the V-shaped groove 2 to saturation; S7.1: Seal the gap 5 between the quartz tube 3 and the conductor core wire 1.1 at both ends of the quartz tube 3; S7.2: There is overflow of the welding metal liquid in the quartz funnel 4; S7.3: The tuning fork 7 is resonated and reciprocated around the outer side of the quartz tube 3 until no bubbles are generated; S8: raising the temperature, heating the quartz tube 3 and the quartz funnel 4, and melting the conductor core wire 1.1 at the welding end, so that the conductor core wire 1.1 is fused with the welding metal liquid; S8.1: The tuning fork 7 is resonated and reciprocated around the outside of the quartz tube 3 until no bubbles are generated; S9: After the conductor core wire 1.1 and the welding metal liquid are completely fused, the heating is stopped; S9.1: heating the mud seal 5 until the mud seal 5 is dried and cracked, and cleaning the mud seal 5; S10: Cooling the surface of the quartz tube 3 with water; S11: After the conductor core wire 1.1 and the welding metal liquid are completely cooled and shaped, the quartz tube 3 is broken; S12: grinding the welded conductor core wire 1.1; S13: Repair the outer layer of the conductor core wire 1.1; S14: The welding of cable 1 is completed.

[0023] When the conductor core wire 1.1 is made of copper, the raw material of the welding metal liquid is red copper, in step S6, the preheating temperature is 1000-1100°C, and in step S8, the heating temperature is 1200-1300°C.

[0024] When the conductor core wire 1.1 is made of aluminum, the raw material of the welding metal liquid is a conductive aluminum alloy, the preheating temperature in step S6 is 600-700°C, and the heating temperature in step S8 is 1200-1300°C.

[0025] A welding device for implementing a casting method for an ultra-high voltage cable conductor joint comprises a quartz tube 3, a quartz funnel 4, a mud seal 5, an electromagnetic heater 6 and a tuning fork 7.

[0026] The diameter of the quartz tube 3 is equal to the wire diameter of the conductor core wire 1.1, and the length of the quartz tube 3 is not less than eight times the wire diameter of the conductor core wire 1.1, that is, the end of the conductor core wire 1.1 to be welded needs to be inserted into the quartz tube 3 at least a distance four times the wire diameter of the conductor core wire 1.1, wherein the conductor core wire 1.1 inserted into the quartz tube 3 is divided into four processing sections, and from the welding end of the conductor core wire 1.1 to the direction away from the other conductor core wire 1.1, there are an inclined cutting section, a melting section, a buffer section, and a cooling section. The inclined cutting section is used to perform an inclined cutting on the welding end of the conductor core wire 1.1 to ensure that the metal conductor wire in the conductor core wire 1.1 is in full contact with the welding metal liquid, so that each metal conductor wire is connected and each metal conductor wire is melted to ensure the connection quality; the melting section melts the conductor core wire 1.1 through the electromagnetic heater 6 to ensure that the conductor core wire 1.1 is fully fused with the welding metal liquid to ensure the welding quality; the buffer section is arranged between the melting section and the cooling section to provide a temperature buffer space to avoid the conductor core wire 1.1 The temperature changes from extremely hot to extremely cold, causing a serious annealing reaction, which is not conducive to the electrical and mechanical stability of the conductor core wire 1.1; the cooling section is used to cool down the residual heat diffused from the welding melt, block the diffusion of heat, limit the heat to the welding area, avoid large-scale temperature rise of the metal conductor wire, and cause damage to the semiconductor tape and the insulation layer of the cable 1. At the same time, when the welding metal liquid or the molten metal conductor wire moves to the end of the quartz tube 3, the cooling section can solidify in time to avoid the molten welding metal liquid or the molten metal conductor wire from diffusing over a long distance.

[0027] like Figure 1 , Figure 2 As shown, a water cooling tube 8 for cooling the quartz tube 3 and the conductor core wire 1.1 is wound around the connection between the end of the quartz tube 3 and the conductor core wire 1.1, so as to form a cooling section inside the quartz tube 3, wherein the water cooling tube 8 is respectively wound around the end area of ​​the quartz tube 3 and the area where the conductor core wire 1.1 just leaves the quartz tube 3, and the water cooling tubes 8 in the two areas are respectively arranged at both ends of the mud seal 5. First, the water-cooling tube 8 wound around the end area of ​​the quartz tube 3 indirectly cools the conductor core 1.1 through the quartz tube 3 in the radial direction, and the water-cooling tube 8 wound around the area where the conductor core 1.1 just leaves the quartz tube 3 directly cools the conductor core 1.1 in the axial direction of the conductor core 1.1, thereby improving the cooling effectiveness and ensuring the cooling effect; at the same time, because the water-cooling tubes 8 in the two areas are respectively arranged at both ends of the mud seal 5, the influence of high temperature on the mud seal 5 during the S6-S8 steps can be fully blocked, thereby slowing down the drying process of the mud seal 5 in the S6-S8 steps, ensuring the effectiveness of the mud seal 5, and forming a blocking air pressure in the gap between the quartz tube 3 and the conductor core 1.1, effectively preventing the molten conductor core 1.1 of the welding metal liquid from leaking out of the gap between the quartz tube 3 and the conductor core 1.1. In step S9.1, only low-temperature heating of 100-200°C is required to clean the mud seal 5 structure layer by layer, and the electrical and mechanical properties of the conductor core 1.1 will not be affected.

[0028] In step S10, the water cooling process does not rely solely on the water cooling tube 8 wound around the quartz tube 3 and the conductor core wire 1.1 for water cooling, but after the electromagnetic heater 6 is removed, a new water cooling tube is wound around the quartz tube 3 to cool together with the water cooling tube 8.

[0029] The mud seal 5 is a structure after the soil is fixed.

[0030] The electromagnetic heater 6 is a conventional device. In the present invention, it is only necessary to ensure that the electromagnetic heater 6 fully covers the molten conductor core wire 1.1 of the quartz tube 3, the area of ​​the welding molten metal and the quartz funnel 4, and heats them stably and evenly.

[0031] The tuning fork 7 is a conventional tuning fork. It is only necessary to select a tuning fork 7 with a resonance frequency closer to the conductor core wire 1.1 according to the material of the conductor core wire 1.1. Then, when executing steps S7.3 and 8.1, the main concentration area is the melting area of ​​the conductor core wire 1.1. If there are bubbles in the welding molten metal and the molten conductor core wire 1.1 molten metal, the bubbles will float up during the resonance process and exchange with the welding molten metal overflowing from the quartz funnel 4, thereby ensuring high-quality forming of the conductor after welding without bubbles.

[0032] like Figure 4As shown, in order to ensure that the bubbles are quickly exchanged with the welding molten metal overflowing from the quartz funnel 4, an exhaust slope 3.1 is provided at the connection between the quartz tube 3 and the quartz funnel 4. When the bubbles float up and collide with the exhaust slope 3.1, the bubbles can quickly move toward the quartz funnel 4 with the vibration to complete the exchange with the welding molten metal overflowing from the quartz funnel 4. The conical structure formed by the exhaust slope 3.1 can be eliminated in step S12.

[0033] Through the design of the present invention, a method for casting a conductor joint of an ultra-high voltage cable is provided, which has high welding quality, low operation difficulty and stable connection quality for the conductor core wire 1.1 of the cable 1, eliminates welding pores, cat's eyes, impurities and other undesirable welding phenomena in the traditional welding process, and avoids severe annealing reaction caused by welding and damage to other structures of the cable 1. In addition, because the quartz tube 3 is a transparent tube, the melting state of the conductor core wire 1.1 and the welding progress can be monitored at any time, thereby ensuring efficient and high-quality completion of welding.

[0034] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. All changes made within the scope of protection of the independent claims of the present invention are within the scope of protection of the present invention.

Claims

1. A method for casting an ultra-high voltage cable conductor joint, characterized in that: The following steps are involved: S1: Take two sections of cable (1) to be welded, cut off the outer structure of the conductor core wire (1.1) at one end of the two sections of cable (1) to be welded, and only retain the conductor core wire (1.1); S2: The welding end of the conductor core wire (1.1) is cut obliquely, and when the welding ends of two sections of the conductor core wire (1.1) are butted against each other, a V-shaped groove (2) is formed; S3: Take a quartz tube (3) with a diameter equal to the diameter of the conductor core wire (1.1), and connect a quartz funnel (4) to the upper middle end of the quartz tube (3); S4: inserting the welding ends of the two conductor core wires (1.1) into the quartz tube (3) from both ends of the quartz tube (3), respectively, the welding ends of the two conductor core wires (1.1) abut against each other to form a V-shaped groove (2), and the V-shaped groove (2) is arranged below the quartz funnel (4); S5: molten welding metal; S6: preheating the quartz tube (3) and the quartz funnel (4); S7: pouring the welding metal liquid into the quartz funnel (4) until the welding metal liquid fills the V-shaped groove (2) to saturation; S8: raising the temperature to heat the quartz tube (3) and the quartz funnel (4) and melt the conductor core wire (1.1) at the welding end, so that the conductor core wire (1.1) and the welding metal liquid are fused; S9: When the conductor core wire (1.1) and the welding metal liquid are completely fused, stop heating; S10: Cooling the surface of the quartz tube (3) with water; S11: After the conductor core wire (1.1) and the welding metal liquid are completely cooled and shaped, the quartz tube (3) is broken; S12: Grinding the welded conductor core wire (1.1); S13: Repair the outer layer of the conductor core wire (1.1); S14: Complete the welding of the cable (1).

2. The method for casting an ultra-high voltage cable conductor joint according to claim 1, characterized in that: The conductor core wire (1.1) is made of copper, the raw material of the welding molten metal is red copper, in step S6, the preheating temperature is 1000-1100° C., and in step S8, the heating temperature is 1200-1300° C.

3. The method for casting an ultra-high voltage cable conductor joint according to claim 1, characterized in that: The conductor core wire (1.1) is made of aluminum, the raw material of the welding molten metal is a conductive aluminum alloy, in step S6, the preheating temperature is 600-700° C., and in step S8, the heating temperature is 1200-1300° C.

4. The method for casting an ultra-high voltage cable conductor joint according to claim 1, characterized in that: Step S7 also includes step S7.1: performing mud sealing (5) on the gap between the quartz tube (3) and the conductor core wire (1.1) at both ends of the quartz tube (3).

5. The method for casting an ultra-high voltage cable conductor joint according to claim 4, characterized in that: Step S7 also includes step S7.2: the welding metal liquid overflows from the quartz funnel (4).

6. The method for casting an ultra-high voltage cable conductor joint according to claim 5, characterized in that: Step S7 also includes step S7.3: using the tuning fork (7) to resonate and move back and forth around the outside of the quartz tube (3) until no bubbles are generated.

7. The method for casting an ultra-high voltage cable conductor joint according to claim 5, characterized in that: Step S8 also includes step S8.1: using a tuning fork (7) to resonate and move back and forth around the outside of the quartz tube (3) until no bubbles are generated.

8. The method for casting an ultra-high voltage cable conductor joint according to claim 4, characterized in that: After completing step S9, the method further includes step S9.1: heating the mud seal (5) until the mud seal (5) is dried and cracked, and cleaning the mud seal (5).

9. The method for casting an ultra-high voltage cable conductor joint according to claim 1, characterized in that: The length of the quartz tube (3) is not less than eight times the diameter of the conductor core wire (1.1).

10. The method for casting an ultra-high voltage cable conductor joint according to claim 9, characterized in that: A water cooling tube (8) for cooling the quartz tube (3) and the conductor core wire (1.1) is wound around the connection between the end of the quartz tube (3) and the conductor core wire (1.1).

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