Connecting structure and connecting method for aluminum alloy cable

Abstract

The invention relates to the technical field of cable connection, in particular to a connection structure and method for an aluminum alloy cable, and the method comprises the steps: selecting an aluminum alloy copper connection structure with consistent performance; an aluminum alloy conductor is welded to the aluminum end terminal welding area through an ultrasonic welding method, the technological parameter initial value of ultrasonic welding is determined according to the welding target parameter, and the initial technological parameter is subjected to negative feedback adjustment according to the trial operation result; whether the ultrasonic welding equipment can meet the welding requirement of the aluminum alloy conductor or not is judged according to the heat input of the ultrasonic welding equipment; the relation between the welding temperature and the target temperature range is evaluated, the change trend of the welding temperature is judged, and the power of ultrasonic welding equipment is adjusted; and after welding is completed, heat treatment and surface treatment are carried out, and double-wall heat shrink tube sealing is carried out on the connecting part. According to the invention, the aluminum alloy cable is connected with the connection structure, the conductivity similar to that of a copper terminal is provided, and the efficiency and stability of current transmission are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of cable connection, and in particular to a connection structure and a connection method for aluminum alloy cables. Background Art

[0002] The aluminum alloy copper connection structure for aluminum alloy cables is usually composed of two materials: aluminum alloy and copper. Aluminum alloy is widely used in power transmission and distribution systems due to its advantages such as light weight, good conductivity and relatively low price. Copper is widely used in electrical connections due to its excellent conductivity and good mechanical properties. The connection structure solves the compatibility problems that may occur when aluminum alloy cables are directly connected to copper equipment by combining these two materials.

[0003] Chinese Patent Publication No.: CN110444987A discloses a connection method and connection structure between an aluminum alloy automobile cable and a copper terminal. The connection method includes: stripping out the aluminum alloy conductor in the aluminum alloy automobile cable, and then welding the aluminum alloy conductor to the copper terminal by ultrasonic welding; coating a layer of high temperature and corrosion resistant sealant layer on the surface of the aluminum alloy conductor at the welding position and curing it; heat shrinking and coating a layer of thermoplastic sleeve on the sealant layer, the aluminum alloy conductor, the copper terminal at the welding position and the outer sheath of the aluminum alloy automobile cable; it can be seen that the connection method and connection structure between the aluminum alloy automobile cable and the copper terminal have the following problems: the aluminum alloy cable is directly connected to the copper conductor, the connection part is improperly handled, and the contact part of the copper-aluminum alloy conductor will produce severe electrochemical corrosion, thereby losing the electrical and mechanical properties of the copper-aluminum connection, and the expansion coefficient and hardness of the aluminum alloy and copper are different, the heat generation of the line under different loads is different, causing metal expansion, and the plastic deformation of the aluminum alloy leads to poor contact. Summary of the invention

[0004] To this end, the present invention provides a connection structure and a connection method for an aluminum alloy cable, so as to overcome the problems in the prior art that the aluminum alloy cable is directly connected to the copper conductor, the connection parts are improperly processed, the contact parts of the copper-aluminum alloy conductors will produce serious electrochemical corrosion, thereby losing the electrical and mechanical properties of the copper-aluminum connection, and the aluminum alloy and copper have different expansion coefficients and hardnesses, the circuit generates different heat under different loads, causing metal expansion, and the aluminum alloy plastic deformation leads to poor contact.

[0005] To achieve the above object, the present invention provides a connection structure and a connection method for aluminum alloy cables, comprising: Step S1, selecting an aluminum alloy copper connection structure with consistent performance according to the chemical properties, electrical properties, mechanical properties and creep properties of the aluminum alloy; Step S2, trimming the outer conductive layer of the aluminum alloy cable, stripping off the aluminum alloy conductor in the aluminum alloy cable, cleaning the exposed part of the aluminum alloy cable, and removing the oxide layer and impurities; Step S3, placing the cleaned aluminum alloy conductor on the aluminum end of the connection structure, ensuring that the conductor is in close contact with the connection structure, and using a crimping tool to crimp the conductor to the aluminum end according to a standard torque value; Step S4, using an ultrasonic welding method to weld the aluminum alloy conductor to the aluminum terminal welding area. Before welding, determine the initial values ​​of the ultrasonic welding process parameters according to the target parameters of the welding, and conduct a trial run with the initial process parameters, and negatively feedback adjust the initial process parameters according to the trial run results; determine whether the ultrasonic welding equipment can meet the welding requirements of the aluminum alloy conductor according to the heat input of the ultrasonic welding equipment; during the welding process, detect the welding temperature according to the initial detection cycle, evaluate the relationship between the welding temperature and the target temperature range, determine the change trend of the welding temperature, and adjust the power of the ultrasonic welding equipment according to the change trend; Step S5, after welding is completed, clean the welding area, remove excess solder or flash, and perform necessary heat treatment and surface treatment; Step S6, after the welding area is cleaned, the connection part is sealed with a double-wall heat shrink tube; The initial values ​​of the process parameters include the initial frequency, initial amplitude and initial welding time of ultrasonic welding, and the target parameters include the target height and target effective area of ​​the aluminum alloy conductor after welding.

[0006] Furthermore, after the test run is stopped, the test piece height and the test piece effective area are checked, and the height difference and area difference between the test piece height and the test piece effective area and the target height and the target effective area are calculated. If the height difference or area difference is greater than the difference evaluation value, it is judged that the specimen cannot meet the target parameter requirements for welding the aluminum alloy conductor and the connecting structure, and the initial process parameters are adjusted according to the actual difference between the specimen height and effective area of ​​the specimen and the target height and target effective area of ​​the pipe product.

[0007] Further, if the height difference is greater than the height difference evaluation value and the test piece height is less than the target height, the initial amplitude of the ultrasonic welding is increased according to the ratio of the height difference to the height difference evaluation value; If the area difference is greater than the area difference evaluation value and the effective area of ​​the specimen is less than the target effective area, the initial welding time of the ultrasonic welding is increased according to the ratio of the area difference to the area difference evaluation value; Among them, the height difference evaluation value is the allowable welding height error value, and the area difference evaluation value is the allowable welding effective area error value.

[0008] Furthermore, the maximum welding temperature value of the aluminum alloy conductor during ultrasonic welding is compared with the target temperature range. If the maximum welding temperature value is greater than or equal to the maximum target temperature, it is judged that the ultrasonic welding equipment can meet the welding requirements of the aluminum alloy conductor; If the maximum welding temperature value is less than the minimum target temperature value, it is determined that the ultrasonic welding equipment does not meet the welding requirements of the aluminum alloy conductor.

[0009] Furthermore, when the ultrasonic welding equipment does not meet the welding requirements of the aluminum alloy conductor, the ultrasonic welding equipment is controlled to perform welding at maximum power, and the initial pressure on the aluminum alloy conductor is increased according to the ratio of the maximum welding temperature value to the maximum target temperature.

[0010] Furthermore, according to the initial detection cycle, the temperature of the aluminum alloy conductor is directly measured by a temperature measuring device such as an infrared thermal imager to detect the welding temperature, and for any welding temperature value, the temperature difference between the target temperature minimum value and the target temperature maximum value is calculated. If the temperature difference is greater than the temperature difference evaluation value when the welding temperature value Ci is lower than the target temperature range, the power of the ultrasonic welding equipment is increased according to the ratio of the temperature difference value to the temperature difference evaluation value; If the temperature difference is greater than the temperature difference evaluation value when the welding temperature value Ci is higher than the target temperature range, the power of the ultrasonic welding equipment is reduced according to the ratio of the temperature difference evaluation value to the temperature difference; Among them, the temperature difference evaluation value is the welding temperature error value.

[0011] Furthermore, when the welding temperature value Ci is within the target temperature range, a welding temperature change curve of the aluminum alloy conductor is drawn according to the welding temperature, and a derivative function of the temperature change curve is obtained, and the temperature change curve of the aluminum alloy conductor and its derivative function are analyzed to determine the change trend of the welding temperature. If the temperature difference of the temperature change curve at any time point is less than the temperature difference evaluation value, and the slope of the temperature change curve at any time point is greater than zero, it is judged that the welding temperature of the aluminum alloy conductor is rising and the welding temperature is approaching the maximum target temperature. If the temperature difference of the temperature change curve at any time point is less than the temperature difference evaluation value, and the curve slope of the temperature change curve at any time point is less than zero, it is judged that the welding temperature of the aluminum alloy conductor is decreasing and the welding temperature is approaching the minimum target temperature.

[0012] Furthermore, when the welding temperature is approaching the maximum target temperature, the power of the ultrasonic welding equipment is reduced according to the rising rate of the welding temperature, and the adjusted power is equal to the product of the initial welding power and the difference between 1 and the slope of the curve; when the welding temperature is approaching the minimum target temperature Ce1, the power of the ultrasonic welding equipment is increased according to the decreasing rate of the welding temperature, and the adjusted power is equal to the quotient of the initial welding power and the difference between 1 and the slope of the curve.

[0013] The present invention also provides a connection structure for aluminum alloy cables, characterized in that it comprises: The copper end is provided with a plurality of connection holes, and the plurality of connection holes are sequentially spaced along the axial direction of the copper end, and are used to realize electrical connection and conduction with the copper equipment; Aluminum terminal, which is used to connect with aluminum alloy cable. The aluminum terminal of the connection structure is made of aluminum alloy. Different materials can be used according to different types of aluminum alloy cables to keep the performance consistent with that of aluminum alloy conductors. It can also be designed into various shapes and sizes according to different needs to increase the contact surface and contact area. The crimping wings are wrapped around the outside of the insulation layer of the cable and are used to transfer part of the external force to the connection structure body.

[0014] Furthermore, the aluminum end includes a terminal welding area and a sealing transition area. The terminal welding area, the welding area surface adopts a knurled embossing structure, and there are welding positioning structures on both sides of the terminal welding area. After ultrasonic welding, the aluminum alloy conductor will be embedded in these knurled embossings; The sealing transition area is located at the front end of the terminal welding area and is used to ensure that the front end has sufficient length to be completely filled with the heat shrink tubing.

[0015] Compared with the prior art, the beneficial effect of the present invention is that ultrasonic welding transmits high-frequency vibration waves to the surfaces of two objects to be welded, and under the application of pressure, the two surfaces of the objects are rubbed against each other, thereby forming a fusion between the molecular layers. Through this method, the oxide film on the surface of the aluminum wire can be effectively destroyed, and the free movement of electrons between different aluminum substrate conductors can be achieved.

[0016] Furthermore, increasing the ultrasonic amplitude can increase the welding energy, thereby promoting the melting and bonding of the welding materials and increasing the welding height; extending the welding time can increase the action time of the ultrasonic energy in the welding area, thereby increasing the welding area; through trial operation simulation and prediction of the results of ultrasonic welding with different process parameters, the trial and error cost and material waste can be reduced, and the process parameters can be quickly adjusted and optimized under different material and process conditions.

[0017] Furthermore, if the heat input of the ultrasonic welding equipment to the aluminum alloy conductor at maximum power is not calculated, it is impossible to accurately judge whether the ultrasonic welding equipment can meet the welding requirements of the aluminum alloy conductor, thereby affecting the subsequent adjustment of the welding process. By quantifying the heating capacity of the ultrasonic welding equipment for the aluminum alloy conductor, the accuracy of the connection process between the aluminum alloy cable and the connection structure is improved.

[0018] Furthermore, if the welding temperature during the welding process is not detected and analyzed, improper control of the welding temperature may cause defects such as pores and cracks in the welding interface, affecting the connection quality. By accurately controlling the welding temperature, the occurrence of these defects can be reduced and the reliability of the connection method can be improved. When the welding temperature is within the target temperature range, the change trend of the welding temperature is determined, thereby increasing the accuracy of temperature control and adjustment. At the same time, proper temperature control can increase the welding speed, thereby improving efficiency.

[0019] Furthermore, if the welding area is not sealed after the aluminum alloy conductor and the connecting mechanism are welded, the aluminum alloy conductor will be directly exposed to the air, and the connecting part will produce electrochemical corrosion in a humid or saline environment. The double-wall heat shrink tube is used to isolate the connecting part from the humid or saline environment to avoid affecting the electrical and mechanical properties of the connecting part.

[0020] Furthermore, the knurled embossing structure helps to destroy the oxide layer on the surface of the aluminum alloy conductor, so that the non-oxidized aluminum alloy conductor directly contacts the surface of the copper conductor, and increases the adhesion of the aluminum alloy conductor to the surface of the copper terminal. The spacing of the embossing points can be controlled at 1 mm, and the embossing depth can be controlled at 0.1 mm.

[0021] Furthermore, since the tensile strength and shear strength of aluminum alloy cables are weaker than those of copper cables, their fatigue strength is also weaker than that of copper cables. Therefore, a special structure is needed to improve the fatigue strength of the aluminum alloy cable and the connection structure at the connection part and to resist the external force during the assembly process. In the connection between the connection structure and the aluminum alloy cable, the weakest link is the area between the tail of the connection structure and the insulation layer of the aluminum alloy cable. Therefore, an additional structure is required to increase the strength of this part, that is, to add an insulation skin crimping wing structure at the tail of the connection structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of the steps of a connection method for a connection structure of an aluminum alloy cable in an embodiment of the present invention; Figure 2 A schematic diagram of a connection method of a connection structure for an aluminum alloy cable in an embodiment of the present invention; Figure 3 This is a schematic diagram of a knurled embossing structure for a connection structure of an aluminum alloy cable in an embodiment of the present invention; Figure 4 This is a schematic diagram of a crimping wing structure for a connection structure of an aluminum alloy cable in an embodiment of the present invention; In the figure: 1-copper end, 2-aluminum end, 3-knurling, 4-sealing transition area, 5-crimping wing, 6-aluminum alloy cable, 7-aluminum alloy conductor, 8-double-wall heat shrink tube. DETAILED DESCRIPTION

[0023] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0025] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0026] In addition, it should be noted that in the description of the present invention, 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] See also Figure 1 As shown, Figure 1 This is a flow chart of the steps of a connection method for a connection structure of an aluminum alloy cable in an embodiment of the present invention; Figure 2 A schematic diagram of a connection method of a connection structure for an aluminum alloy cable in an embodiment of the present invention; Figure 3 This is a schematic diagram of a knurled embossing structure for a connection structure of an aluminum alloy cable in an embodiment of the present invention; Figure 4 The present invention is a schematic diagram of a crimping wing structure for a connection structure of an aluminum alloy cable in an embodiment of the present invention.

[0028] The present invention provides a connection method for a connection structure of an aluminum alloy cable, comprising: Step S1, selecting an aluminum alloy copper connection structure with consistent performance according to the chemical properties, electrical properties, mechanical properties and creep properties of the aluminum alloy; Step S2, trimming the outer conductor layer of the aluminum alloy cable, stripping off the aluminum alloy conductor in the aluminum alloy cable, cleaning the exposed part of the aluminum alloy cable, removing the oxide layer and impurities to ensure good contact; Step S3, placing the cleaned aluminum alloy conductor on the aluminum end of the connection structure, ensuring that the conductor is in close contact with the connection structure, and using a crimping tool to crimp the conductor to the aluminum end according to a standard torque value to ensure a firm connection; Step S4, using an ultrasonic welding method to weld the aluminum alloy conductor to the aluminum terminal welding area. Before welding, determine the initial values ​​of the ultrasonic welding process parameters according to the target parameters of the welding, and conduct a trial run with the initial process parameters, and negatively feedback adjust the initial process parameters according to the trial run results; determine whether the ultrasonic welding equipment can meet the welding requirements of the aluminum alloy conductor according to the heat input of the ultrasonic welding equipment; during the welding process, detect the welding temperature according to the initial detection cycle, evaluate the relationship between the welding temperature and the target temperature range, determine the change trend of the welding temperature, and adjust the power of the ultrasonic welding equipment according to the change trend; Step S5, after welding is completed, clean the welding area, remove excess solder or flash, and perform necessary heat treatment or surface treatment; Step S6, after the welding area is cleaned, the connection part is sealed with a double-wall heat shrink tube; Specifically, aluminum and oxygen have a strong affinity. Even at room temperature, dense aluminum oxide will form on its surface the moment it comes into contact with air. Although the oxide film prevents oxygen from diffusing into it and plays a good role in corrosion protection in the atmosphere, its good insulation effect prevents electrons from moving from one aluminum-based conductor to another, that is, electrons can only move within the aluminum substrate. Ultrasonic welding transmits high-frequency vibration waves to the surfaces of two objects to be welded, and under the condition of applying pressure, the surfaces of the two objects rub against each other, thereby forming a fusion between the molecular layers. This method can effectively destroy the oxide film on the surface of the aluminum wire and realize the free movement of electrons between different aluminum-based conductors.

[0029] The welding process includes: using the welding machine's fixture to fix the material to ensure that it does not move during the welding process; setting the frequency, amplitude, and welding time of the ultrasonic welding machine according to the material and welding requirements; starting the welding machine, and applying appropriate pressure by pressing the welding head on the material through the welding machine's pressure system; the ultrasonic welding head begins to generate high-frequency vibrations, which are transmitted to the material through the welding head. This vibration generates heat in the welding area, causing the material to melt locally; when the material is partially melted, the pressure is maintained so that the molten material re-solidifies during the cooling process to form a weld.

[0030] During the ultrasonic welding process, the initial values ​​of the process parameters of ultrasonic welding are determined according to the target parameters of welding. The initial values ​​of the process parameters include the initial frequency, initial amplitude, and initial welding time of ultrasonic welding. The target parameters include the target height and target effective area of ​​the aluminum alloy conductor after welding. A trial run is carried out with the initial process parameters.

[0031] In this embodiment, a welding target height and a target effective area of ​​the aluminum alloy conductor and the connection structure are set. After the test run is stopped, the test piece height and the test piece effective area of ​​the test run are checked, and the height difference and area difference between the test piece height and the test piece effective area and the target height and the target effective area are calculated. If the height difference and the area difference are less than or equal to the difference evaluation value, it is judged that the test piece can meet the target parameter requirements for welding the aluminum alloy conductor and the connecting structure; If the height difference or area difference is greater than the difference evaluation value, it is judged that the specimen cannot meet the target parameter requirements for welding the aluminum alloy conductor and the connecting structure. The initial process parameters are adjusted according to the actual difference between the specimen height and effective area and the target height and effective area of ​​the pipe product. Wherein, if the height difference is greater than the height difference evaluation value and the test piece height is less than the target height, the initial amplitude of the ultrasonic welding is increased according to the ratio of the height difference to the height difference evaluation value; If the area difference is greater than the area difference evaluation value and the effective area of ​​the specimen is less than the target effective area, the initial welding time of the ultrasonic welding is increased according to the ratio of the area difference to the area difference evaluation value; The height difference evaluation value is the welding height error value, which is set between ±0.1 mm and ±0.5 mm, and the area difference evaluation value is the welding effective area error value, which is set between ±0.1 square millimeters and ±0.5 square millimeters.

[0032] Specifically, increasing the ultrasonic amplitude can increase the welding energy, thereby promoting the melting and bonding of welding materials and increasing the welding height; extending the welding time can increase the action time of ultrasonic energy in the welding area, thereby increasing the welding area; through trial operation simulation and prediction of the results of ultrasonic welding with different process parameters, the trial and error cost and material waste can be reduced, and the process parameters can be quickly adjusted and optimized under different material and process conditions.

[0033] Calculate the heat input of the ultrasonic welding equipment for the aluminum alloy conductor at maximum power. The heat input is equal to the product of the ultrasonic power and the welding time and the quotient of the welding area. The maximum welding temperature value that the aluminum alloy conductor can reach is calculated based on the heat input. The maximum welding temperature value is positively correlated with the heat input. The maximum welding temperature value is equal to the product of the conversion coefficient of heat and temperature, the heat input and the reference temperature value. The maximum welding temperature value of the aluminum alloy conductor during ultrasonic welding is compared with the target temperature range. The upper limit of the target temperature range is the maximum value of the target temperature, and the lower limit is the minimum value of the target temperature. If the maximum welding temperature value is greater than or equal to the maximum target temperature, it is judged that the ultrasonic welding equipment can meet the welding requirements of the aluminum alloy conductor; If the maximum welding temperature value is less than the minimum target temperature value, it is judged that the ultrasonic welding equipment does not meet the welding requirements of the aluminum alloy conductor. When the ultrasonic welding equipment does not meet the welding requirements of the aluminum alloy conductor, the ultrasonic welding equipment is controlled to perform welding at the maximum power, and the initial pressure on the aluminum alloy conductor is increased according to the ratio of the maximum welding temperature value to the maximum target temperature.

[0034] Specifically, if the heat input of the ultrasonic welding equipment to the aluminum alloy conductor at maximum power is not calculated, it is impossible to accurately judge whether the ultrasonic welding equipment can meet the welding requirements of the aluminum alloy conductor, which will affect the subsequent adjustment of the welding process. By quantifying the heating capacity of the ultrasonic welding equipment for the aluminum alloy conductor, the accuracy of the connection process between the aluminum alloy cable and the connection structure is improved.

[0035] In this embodiment, an initial detection cycle is provided, and according to the initial detection cycle, the temperature of the aluminum alloy conductor is directly measured by a temperature measuring device such as an infrared thermal imager to detect the welding temperature. The welding temperature includes an initial welding temperature value C0, a first welding temperature value C1, a second welding temperature value C2, ..., an nth welding temperature value Cn For any welding temperature value Ci, i=1, 2, ..., n, calculate the temperature difference between it and the minimum target temperature and the maximum target temperature. When the welding temperature is lower than the target temperature range, the temperature difference is the difference between the welding temperature and the minimum target temperature. When the welding temperature is higher than the target temperature range, the temperature difference is the difference between the welding temperature and the maximum target temperature. If the temperature difference is greater than the temperature difference evaluation value when the welding temperature value Ci is lower than the target temperature range, the power of the ultrasonic welding equipment is increased according to the ratio of the temperature difference value to the temperature difference evaluation value. If the temperature difference is greater than the temperature difference evaluation value when the welding temperature value Ci is higher than the target temperature range, the power of the ultrasonic welding equipment is reduced according to the ratio of the temperature difference evaluation value to the temperature difference. The temperature difference evaluation value is the welding temperature error value, and the temperature error range of ultrasonic welding is set between ±5°C; If the welding temperature value Ci is within the target temperature range, a welding temperature change curve of the aluminum alloy conductor is drawn according to the welding temperature, and a derivative function of the temperature change curve is obtained, and the temperature change curve of the aluminum alloy conductor and its derivative function are analyzed to determine the change trend of the welding temperature Ci; If the temperature difference of the temperature change curve at any time point is less than the temperature difference evaluation value, and the slope of the temperature change curve at any time point is greater than zero, it is judged that the welding temperature of the aluminum alloy conductor is rising and the welding temperature is approaching the maximum target temperature. If the temperature difference of the temperature change curve at any time point is less than the temperature difference evaluation value, and the slope of the temperature change curve at any time point is less than zero, it is judged that the welding temperature of the aluminum alloy conductor is decreasing and the welding temperature is approaching the minimum target temperature. When the welding temperature value Ci is less than the middle value of the target temperature range, the temperature difference is the difference between the welding temperature value Ci and the minimum target temperature. When the welding temperature value Ci is greater than the middle value of the target temperature range, the temperature difference is the difference between the welding temperature value Ci and the maximum target temperature. The middle value of the target temperature range is equal to the middle value between the minimum target temperature and the maximum target temperature. When the welding temperature is approaching the maximum target temperature, the power of the ultrasonic welding equipment is reduced according to the rising rate of the welding temperature, and the adjusted power is equal to the product of the initial welding power and the difference between 1 and the slope of the curve; when the welding temperature is approaching the minimum target temperature Ce1, the power of the ultrasonic welding equipment is increased according to the decreasing rate of the welding temperature, and the adjusted power is equal to the quotient of the initial welding power and the difference between 1 and the slope of the curve.

[0036] Specifically, if the welding temperature during the welding process is not detected and analyzed, improper control of the welding temperature may lead to defects such as pores and cracks in the welding interface, affecting the connection quality. By accurately controlling the welding temperature, the occurrence of these defects can be reduced and the reliability of the connection method can be improved. When the welding temperature is within the target temperature range, the change trend of the welding temperature is determined, thereby increasing the accuracy of temperature control and adjustment. At the same time, proper temperature control can increase the welding speed, thereby improving efficiency.

[0037] The outer wall of the double-wall heat shrinkable tube shrinks after being heated at high temperature, and the solid glue on the inner wall melts into liquid glue. After fully flowing, it covers the terminal connection part and the surface of the cable insulation skin. After cooling and solidification, it achieves a sealing effect. The wall thickness of the double-wall heat shrinkable tube after heat shrinkage treatment is 1 to 1.5 mm.

[0038] Specifically, if the welding area is not sealed after the aluminum alloy conductor and the connecting mechanism are welded, the aluminum alloy conductor will be directly exposed to the air, and the connecting parts will produce electrochemical corrosion in a humid or salinized environment. The double-wall heat shrink tubing is used to isolate the connecting parts from the humid or salinized environment to avoid affecting the electrical and mechanical properties of the connecting parts.

[0039] The present invention provides a connection structure for aluminum alloy cables, comprising: The copper end is provided with a plurality of connection holes, and the plurality of connection holes are sequentially spaced along the axial direction of the copper end, and are used to realize electrical connection and conduction with the copper equipment; Aluminum terminal, which is used to connect with aluminum alloy cable. The aluminum terminal of the connection structure is made of aluminum alloy. Different materials can be used according to different types of aluminum alloy cables to keep the performance consistent with that of aluminum alloy conductors. It can also be designed into various shapes and sizes according to different needs to increase the contact surface and contact area. The aluminum end includes the terminal welding area and the sealing transition area; The terminal welding area, the welding area surface adopts a knurled embossing structure, and there are welding positioning structures on both sides of the terminal welding area. After ultrasonic welding, the aluminum alloy conductor will be embedded in these knurled embossings; Specifically, the knurled embossing structure helps to destroy the oxide layer on the surface of the aluminum alloy conductor, allowing the non-oxidized aluminum alloy conductor to directly contact the surface of the copper conductor, and increase the adhesion of the aluminum alloy conductor to the surface of the copper terminal. The spacing of the embossing points can be controlled at 1mm, and the embossing depth can be controlled at 0.1mm.

[0040] The sealing transition area is located at the front end of the terminal welding area and is used to ensure that the front end has sufficient length to be completely filled with the heat shrink tube; Specifically, since the welding height of large-diameter aluminum alloy cables is relatively large, and the larger the cable diameter, the greater the difference in height with the surface of the connecting structure. For example, the difference in height of a 120 square millimeter aluminum alloy cable can reach 3 to 5 mm; therefore, sufficient sealing transition area must be reserved at the front end of the terminal welding area to ensure that the front end has sufficient length to be completely filled with the heat shrink tube. The length of this area can be controlled at 10 to 16 mm.

[0041] The crimping wings, which embrace the outside of the insulation layer of the cable, are used to transfer part of the external force to the connection structure body, thereby alleviating the direct external force and fatigue load on the root of the aluminum alloy cable.

[0042] Specifically, since the tensile strength and shear strength of aluminum alloy cables are weaker than those of copper cables, their fatigue strength is also weaker than that of copper cables. Therefore, a special structure is needed to improve the fatigue strength of the aluminum alloy cable and the connection structure at the connection part and to resist the external force during the assembly process. In the connection between the connection structure and the aluminum alloy cable, the weakest link is the area between the tail of the connection structure and the insulation layer of the aluminum alloy cable. Therefore, an additional structure is required to increase the strength of this part, that is, to add an insulation skin crimping wing structure at the tail of the connection structure.

[0043] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A connection method for a connection structure of an aluminum alloy cable, characterized in that: include: Step S1, selecting an aluminum alloy copper connection structure with consistent performance according to the chemical properties, electrical properties, mechanical properties and creep properties of the aluminum alloy; Step S2, trimming the outer conductive layer of the aluminum alloy cable, stripping off the aluminum alloy conductor in the aluminum alloy cable, cleaning the exposed part of the aluminum alloy cable, and removing the oxide layer and impurities; Step S3, placing the cleaned aluminum alloy conductor on the aluminum end of the connection structure, ensuring that the conductor is in close contact with the connection structure, and using a crimping tool to crimp the conductor to the aluminum end according to a standard torque value; Step S4, welding the aluminum alloy conductor to the aluminum end by ultrasonic welding, determining the initial values ​​of the ultrasonic welding process parameters according to the target parameters of the welding before welding, and conducting a trial run with the initial process parameters, and adjusting the initial process parameters by negative feedback according to the trial run results; judging whether the ultrasonic welding equipment can meet the welding requirements of the aluminum alloy conductor according to the heat input of the ultrasonic welding equipment; During the welding process, the welding temperature is detected according to the initial detection cycle, the relationship between the welding temperature and the target temperature range is evaluated, the change trend of the welding temperature is determined, and the power of the ultrasonic welding equipment is adjusted according to the change trend; Step S5, after welding is completed, clean the welding area, remove excess solder or flash, and perform necessary heat treatment and surface treatment; Step S6, after the welding area is cleaned, the connection part is sealed with a double-wall heat shrink tube; The initial values ​​of the process parameters include the initial frequency, initial amplitude and initial welding time of ultrasonic welding, and the target parameters include the target height and target effective area of ​​the aluminum alloy conductor after welding.

2. The connection method for the connection structure of aluminum alloy cables according to claim 1, characterized in that: The process of negatively feedback adjusting the initial process parameters according to the trial operation results includes: After the test run is stopped, the test specimen height and effective area are checked, and the height and area differences between the test specimen height and effective area and the target height and effective area are calculated. If the height difference or area difference is greater than the difference evaluation value, it is judged that the specimen cannot meet the target parameter requirements for welding the aluminum alloy conductor and the connecting structure, and the initial process parameters are adjusted according to the actual difference between the specimen height and effective area of ​​the specimen and the target height and target effective area of ​​the pipe product.

3. The connection method for the connection structure of aluminum alloy cables according to claim 2, characterized in that: The process of adjusting the initial process parameters includes: If the height difference is greater than the height difference evaluation value and the test piece height is less than the target height, the initial amplitude of the ultrasonic welding is increased according to the ratio of the height difference to the height difference evaluation value; If the area difference is greater than the area difference evaluation value and the effective area of ​​the specimen is less than the target effective area, the initial welding time of the ultrasonic welding is increased according to the ratio of the area difference to the area difference evaluation value; Among them, the height difference evaluation value is the allowable welding height error value, and the area difference evaluation value is the allowable welding effective area error value.

4. The connection method for the connection structure of aluminum alloy cables according to claim 3, characterized in that: The process of determining whether the ultrasonic welding equipment can meet the welding requirements of the aluminum alloy conductor includes: The maximum welding temperature of aluminum alloy conductors during ultrasonic welding is compared with the target temperature range. If the maximum welding temperature value is greater than or equal to the maximum target temperature, it is determined that the ultrasonic welding equipment can meet the welding requirements of the aluminum alloy conductor; If the maximum welding temperature value is less than the minimum target temperature value, it is determined that the ultrasonic welding equipment does not meet the welding requirements of the aluminum alloy conductor.

5. The connection method for the connection structure of aluminum alloy cables according to claim 4, characterized in that: When the ultrasonic welding equipment does not meet the welding requirements of the aluminum alloy conductor, the ultrasonic welding equipment is controlled to perform welding at the maximum power, and the initial pressure on the aluminum alloy conductor is increased according to the ratio of the maximum welding temperature value to the maximum target temperature.

6. The connection method for the connection structure of aluminum alloy cables according to claim 1, characterized in that: The process of evaluating the relationship between the welding temperature and the target temperature range includes, According to the initial detection cycle, the temperature of the aluminum alloy conductor is directly measured by a temperature measuring device to detect the welding temperature, and for any welding temperature value, the temperature difference between the target temperature minimum value and the target temperature maximum value is calculated. If the temperature difference is greater than the temperature difference evaluation value when the welding temperature value Ci is lower than the target temperature range, the power of the ultrasonic welding equipment is increased according to the ratio of the temperature difference value to the temperature difference evaluation value; If the temperature difference is greater than the temperature difference evaluation value when the welding temperature value Ci is higher than the target temperature range, the power of the ultrasonic welding equipment is reduced according to the ratio of the temperature difference evaluation value to the temperature difference; Among them, the temperature difference evaluation value is the welding temperature error value.

7. The connection method for the connection structure of aluminum alloy cables according to claim 1, characterized in that: The process of judging the change trend of the welding temperature includes: When the welding temperature value Ci is within the target temperature range, the welding temperature change curve of the aluminum alloy conductor is drawn according to the welding temperature, and the derivative function of the temperature change curve is obtained. The temperature change curve of the aluminum alloy conductor and its derivative function are analyzed to determine the change trend of the welding temperature. If the temperature difference of the temperature change curve at any time point is less than the temperature difference evaluation value, and the slope of the temperature change curve at any time point is greater than zero, it is judged that the welding temperature of the aluminum alloy conductor is rising and the welding temperature is approaching the maximum target temperature. If the temperature difference of the temperature change curve at any time point is less than the temperature difference evaluation value, and the curve slope of the temperature change curve at any time point is less than zero, it is judged that the welding temperature of the aluminum alloy conductor is decreasing and the welding temperature is approaching the minimum target temperature.

8. The connection method for the connection structure of aluminum alloy cables according to claim 1, characterized in that: When the welding temperature is approaching the maximum target temperature, the power of the ultrasonic welding equipment is reduced according to the rising rate of the welding temperature, and the adjusted power is equal to the product of the initial welding power and the difference between 1 and the slope of the curve; when the welding temperature is approaching the minimum target temperature Ce1, the power of the ultrasonic welding equipment is increased according to the decreasing rate of the welding temperature, and the adjusted power is equal to the quotient of the initial welding power and the difference between 1 and the slope of the curve.

9. A connection structure for an aluminum alloy cable, using the connection method for the connection structure for an aluminum alloy cable according to any one of claims 1 to 8, characterized in that: include, The copper end is provided with a plurality of connection holes, and the plurality of connection holes are sequentially spaced along the axial direction of the copper end, and are used to realize electrical connection and conduction with the copper equipment; Aluminum terminal, which is used to connect with aluminum alloy cable. The aluminum terminal of the connection structure is made of aluminum alloy. Different materials can be used according to different types of aluminum alloy cables to keep the performance consistent with that of aluminum alloy conductors. It can also be designed into various shapes and sizes according to different needs to increase the contact surface and contact area. The crimping wings are wrapped around the outside of the insulation layer of the cable and are used to transfer part of the external force to the connection structure body.

10. The connection structure for aluminum alloy cables according to claim 9, characterized in that: The aluminum end includes the terminal welding area and the sealing transition area. The terminal welding area, the welding area surface adopts a knurled embossing structure, and there are welding positioning structures on both sides of the terminal welding area. After ultrasonic welding, the aluminum alloy conductor will be embedded in these knurled embossings; The sealing transition area is located at the front end of the terminal welding area and is used to ensure that the front end has sufficient length to be completely filled with the heat shrink tubing.

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