Crimping type cable connector based on nickel-titanium shape memory alloy and connection method

Abstract

The invention relates to the technical field of cable connection, in particular to a crimping type cable connector based on nickel-titanium shape memory alloy and a connection method. The connector comprises a connecting pipe and a copper lining, the connecting pipe is a nickel-titanium shape memory alloy cylinder, and the copper lining is tightly attached to the inner wall of the connecting pipe. The shape memory effect of the nickel-titanium shape memory alloy can ensure uniform crimping and avoid stress concentration. The nickel-titanium shape memory alloy has a strong crimping effect, so that the cable connector has excellent mechanical performance and stability, and the service life of the connector is prolonged. The nickel-titanium shape memory alloy has the characteristics of corrosion resistance and high and low temperature resistance, and can be suitable for severe environments. The copper lining tightly attached to the interior of the connecting pipe can remarkably reduce contact resistance, enhance electrical connection and reduce energy loss. The cable connector disclosed by the invention is extremely simple and convenient to install on an engineering site, and crimping can be completed by heating without a complicated tool.

Description

Technical Field

[0001] The present invention relates to the technical field of cable connection, and particularly relates to a crimp-type cable connector based on nickel-titanium shape memory alloy and a connection method thereof. Background Art

[0002] As a key component in the cable power transmission system, the performance of the cable connector is directly related to the operation safety and efficiency of the entire power system. In modern power systems such as high-voltage power transmission, rail transit, and new energy power generation, the cable connector not only has to withstand the long-term action of high voltage and large current, but also has to cope with the influence of complex mechanical stress and environmental factors. This often requires the connector to have better anti-loosening performance, corrosion resistance, and longer service life.

[0003] Traditional cable joints generally adopt the hexagonal circumferential pressure connection method, that is, through the externally applied mechanical pressure, the metal sleeve of the connector undergoes plastic deformation to tightly wrap the cable conductor, thereby realizing the electrical connection and mechanical fixation of the cable core. Although this connection method meets the basic electrical connection requirements to a certain extent, many technical limitations are exposed in practical applications. First, the hexagonal circumferential pressure connection method will produce significant stress concentration at the joint. When the cable is subjected to mechanical vibration, temperature change, or external tensile force, these stress concentration points are prone to looseness, or the initiation and propagation of microcracks are caused, ultimately leading to the fracture and failure of the joint. In addition, the on-site installation difficulty of using this method is relatively high, and it is necessary to precisely control the crimping force and angle. Improper operation may result in loose crimping or over-crimping, affecting the connection quality.

[0004] Therefore, developing a new type of cable connector has important engineering significance and market demand. The new type of cable connector should be able to reduce stress concentration, avoid the generation of looseness and cracks, and have high electrical connection reliability. At the same time, it has strong environmental adaptability, can withstand complex environments such as corrosion, high and low temperatures, and has a long service life. In addition, it can simplify the on-site installation process and reduce the technical dependence on construction personnel. Solving the technical bottleneck of the traditional connection method through technological innovation will provide an important guarantee for the safe and stable operation of the power system, and at the same time will promote the progress of cable connection technology and the development of the industry. Summary of the Invention

[0005] The purpose of the present invention is to provide a crimp-type cable connector based on nickel-titanium shape memory alloy and a connection method thereof. By utilizing the characteristics of nickel-titanium shape memory alloy, the connector can achieve a tight connection to the cable joint and resist deformation during the normal operation state of the cable, thereby improving the reliability of the cable connector.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] A crimp-type cable connector based on nickel-titanium shape memory alloy, comprising a connecting tube and a copper inner lining; the connecting tube is a nickel-titanium shape memory alloy cylinder; the copper inner lining is closely attached to the inner wall of the connecting tube.

[0008] Preferably, the material of the connecting tube is nickel-titanium shape memory alloy with a phase change temperature of 50 - 60 °C.

[0009] Preferably, for the connecting tube, when the temperature is higher than the phase change temperature of the nickel-titanium shape memory alloy, the diameter of the cylinder is slightly smaller than the diameter of the cable core (the diameter of the cylinder is 0.1 - 0.2 mm smaller than the diameter of the cable core), and when the temperature is lower than the phase change temperature of the nickel-titanium shape memory alloy, the diameter of the cylinder is slightly larger than the diameter of the cable core (the diameter of the cylinder is 2 - 3 mm larger than the diameter of the cable core).

[0010] Preferably, the copper inner lining is a copper strip, and multiple copper strips are symmetrically arranged and adhered to the inner wall of the connecting tube using conductive adhesive.

[0011] Preferably, the conductive adhesive is a mixture with resin as the matrix and conductive powder as the filler.

[0012] A crimp-type cable connection method based on nickel-titanium shape memory alloy, using the above connector, the specific steps are as follows:

[0013] Step 1: Pretreatment of the cable. Strip the insulation layer at the end of the cable to expose the cable core; clean the surface of the cable core to ensure there is no oxide layer or dirt.

[0014] Step 2: Install the connector. Under the condition that the temperature is lower than the phase change temperature of the nickel-titanium shape memory alloy, cold-expand the diameter of the connecting tube so that its inner diameter is larger than the outer diameter of the cable conductor; put the cold-expanded connector on the cable conductor.

[0015] Step 3: Heat and fasten. Use a heating device to heat the connector to a temperature higher than the phase change temperature of the nickel-titanium shape memory alloy to make it return to the preset crimping shape and tightly wrap the cable conductor.

[0016] Step 4: Cool and shape. After stopping heating, the connector cools to room temperature, maintains the crimping shape, and check whether the crimping quality meets the requirements.

[0017] Step 5: Clean the connector, wrap insulating material outside the connector to complete the cable connection.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The shape memory effect of the nickel-titanium shape memory alloy can ensure uniform crimping and avoid stress concentration. The nickel-titanium shape memory alloy has a strong crimping effect, enabling the cable connector to have excellent mechanical properties and stability, and extending the service life of the connector. The nickel-titanium shape memory alloy has the characteristics of corrosion resistance and resistance to high and low temperatures, and can be applied to harsh environments. The closely fitting copper inner lining inside the connecting tube can significantly reduce the contact resistance, enhance the electrical connection, and reduce energy loss. The cable connector described in the present invention is extremely simple to install at the engineering site, without the need for complex tools, and the crimping can be completed by heating. Description of the Drawings

[0020] Figure 1 Cross-sectional view of the preset crimping shape for the cable connector;

[0021] Figure 2 Cross-sectional view of the cable connector after low-temperature diameter expansion;

[0022] Figure 3 Cross-sectional view at the cable connector after the cable connection is completed;

[0023] In the figure: 1 - connecting tube; 2 - copper inner lining; 3 - outer insulation layer; 4 - cable core. Detailed Embodiments

[0024] The following further describes the detailed embodiments of the present invention in conjunction with the drawings and technical solutions.

[0025] A crimping-type cable connector based on a nickel-titanium shape memory alloy according to the present invention, as Figure 1 shown, includes a connecting tube 1 and a copper inner lining 2; the connecting tube 1 is a nickel-titanium shape memory alloy cylinder; the copper inner lining 2 is closely attached to the inner wall of the connecting tube 1.

[0026] Preferably, the material of the connecting tube 1 is a nickel-titanium shape memory alloy with a phase transition temperature of 50 - 60 °C. The nickel-titanium shape memory alloy has high flexibility at temperatures below the phase transition temperature (martensite phase) and can expand in diameter; at temperatures above the phase transition temperature (austenite phase), it returns to the preset shape, achieves fastening, and resists deformation.

[0027] Preferably, the connecting tube 1 has a preset crimping shape (cylindrical shape) at a temperature above the phase transition temperature (austenite phase), and the diameter of the cylinder is slightly smaller than the diameter of the cable core.

[0028] Preferably, the copper inner lining 2 is a copper strip, and multiple copper strips are symmetrically arranged and adhered to the inner wall of the connecting tube 1 using conductive adhesive to enhance the electrical connection performance of the cable core 4.

[0029] Preferably, the conductive adhesive is a mixture with a resin as the matrix and conductive powder as the filler.

[0030] A crimping-type cable connection method for a nickel-titanium shape memory alloy, using the above connector, the steps are as follows:

[0031] Step 1: Pretreatment of the cable. Strip the insulating layer from the end of the cable to expose the cable core 4. Clean the surface of the cable core 4 to ensure that there is no oxide layer or dirt.

[0032] Step 2: Install the connector. In a low-temperature environment (below the phase transition temperature), fix the connecting tube 1, and use a mechanical diameter-expanding machine to push the diameter-expanding head through mechanical force (such as hydraulic pressure or air pressure), ensuring that the axis of the connecting tube 1 is consistent with the movement direction of the diameter-expanding head, applying a radial force to the connecting tube 1 to achieve cold expansion of the connecting tube 1, so that the inner diameter of the connecting tube 1 is larger than the outer diameter of the cable conductor 4, as Figure 2 shown. Slip the expanded connector over the cable conductor 4.

[0033] Step 3: Heat and fasten. Use a heating device (such as a hot air gun or a heating coil) to heat the connector to a temperature higher than the phase transition temperature of the nickel-titanium shape memory alloy, so that it returns to the preset crimping shape and tightly wraps the cable conductor 4.

[0034] Step 4: Cool and shape. After stopping heating, the connector cools to room temperature, maintains the crimping shape, and checks whether the crimping quality meets the requirements.

[0035] Step 5: Clean the connector, wrap an insulating material around the outside of the connector to form an outer insulating layer 3, and complete the cable connection, as Figure 3 shown.

[0036] Example 1

[0037] Step 1: For a copper-core cable with a diameter of 10 mm, strip the insulating layers from the ends of the two cables, and each cable exposes a 10-mm-long cable core. Clean the surface of the cable core to ensure that there is no oxide layer or dirt.

[0038] Step 2: Select a nickel-titanium shape memory alloy cable connector with a copper inner lining thickness of 0.5 mm, an inner diameter of 9.9 mm, a length of 20 mm, and a phase transition temperature of 50 degrees Celsius. Expand the connector at 20°C so that its inner diameter is 12 mm. Slip the expanded connector body over the cable core.

[0039] Step 3: Use a hot air gun to heat the connector to 70°C to make it return to the preset annular crimping shape and tightly wrap the cable conductor.

[0040] Step 4: After stopping heating, the connector cools to room temperature, maintains the crimping shape, and checks the crimping quality. Touch the two probes of the multimeter to the cable cores at both ends of the connector respectively, and measure that the resistance is almost zero, indicating that the two cable cores are in good contact and the crimping quality meets the requirements. Complete the crimping of the cable cores.

[0041] Step 5: Clean the surface of the connector to ensure there is no dust or oil stain. Select a heat shrinkable tube with a diameter slightly larger than the outer diameter of the connector and slip it over the connector. Use a hot air gun to heat evenly from the middle to both ends, so that the heat shrinkable tube tightly wraps around the connector on the outside of the connector to form an outer insulating layer. Check that the appearance of the insulating layer is intact to complete the cable connection.

[0042] Example 2

[0043] Step 1: Select an aluminum core cable with a diameter of 20 mm, strip the insulating layers at both ends of the two cables, and expose 20 mm long conductors on each cable. Clean the surface of the conductors to ensure there is no oxide layer or dirt.

[0044] Step 2: Select a nickel-titanium shape memory alloy cable connector with a copper lining thickness of 0.5 mm, an inner diameter of 19.9 mm, a length of 40 mm, and a phase change temperature of 60 °C. Expand the diameter of the connector at 20 °C so that its inner diameter is 22 mm. Slip the expanded connector body over the conductor.

[0045] Step 3: Use a heating coil to heat the connector to 80 °C to restore its preset cylindrical crimping shape and tightly wrap the cable conductor.

[0046] Step 4: After stopping heating, the connector cools to room temperature and maintains the crimping shape. Check the crimping quality. Touch the two probes of the multimeter to the cable cores at both ends of the connector respectively, and measure that the resistance is almost zero, indicating that the cable cores at both ends are in good contact and the crimping quality meets the requirements. Complete the crimping of the cable cores.

[0047] Step 5: Clean the surface of the cable connector to ensure there is no dust or oil stain. Wind a polytetrafluoroethylene insulating layer outside the connector. Select a heat shrinkable tube with a diameter slightly larger than the outer diameter of the connector and slip it over the connector. Use a hot air gun to heat evenly from the middle to both ends, so that the heat shrinkable tube tightly wraps around the connector on the outside of the connector to form an outer insulating layer. Check that the appearance of the insulating layer is intact to complete the cable connection.

[0048] Example 3

[0049] Step 1: For a copper core cable with a diameter of 15 mm, strip the insulating layers at both ends of the two cables, and expose 15 mm long cable cores on each cable. Clean the surface of the cable cores to ensure there is no oxide layer or dirt.

[0050] Step 2: Select a nickel-titanium shape memory alloy cable connector with a copper lining thickness of 0.5 mm, an inner diameter of 14.9 mm, a length of 30 mm, and a phase change temperature of 55 °C. Expand the diameter of the connector at 20 °C so that its inner diameter is 17 mm. Slip the expanded connector body over the cable cores.

[0051] Step 3: Use a hot air gun to heat the connector to 75 °C to restore its preset annular crimp shape and tightly wrap the cable conductor.

[0052] Step 4: After stopping heating, the connector cools to room temperature, maintaining the crimp shape. Check the crimp quality. Touch the two probes of the multimeter to the cable cores at both ends of the connector respectively, and the measured resistance is almost zero, indicating that the two cable cores are in good contact and the crimp quality meets the requirements. Complete the crimping of the cable cores.

[0053] Step 5: Clean the surface of the connector to ensure there is no dust or oil. Select a heat shrinkable tube with a diameter slightly larger than the outer diameter of the connector and slip it over the connector. Use a hot air gun to heat evenly from the middle to both ends, so that the heat shrinkable tube tightly wraps around the connector on the outside of the connector to form an outer insulation layer. Check that the appearance of the insulation layer is intact to complete the cable connection.

Claims

1. A crimp type cable connector based on nickel-titanium shape memory alloy, characterized in that: The connector comprises a connecting tube and a copper lining; the connecting tube is a nickel-titanium shape memory alloy cylinder; the copper lining is tightly fitted to the inner wall of the connecting tube.

2. A crimp-type cable connector based on nickel-titanium shape memory alloy according to claim 1, characterized in that: The material of the connecting pipe is a nickel-titanium shape memory alloy with a phase transition temperature of 50-60 degrees Celsius.

3. A crimp-type cable connector based on nickel-titanium shape memory alloy according to claim 1, characterized in that: The connecting tube has a cylinder diameter slightly smaller than the cable core diameter when the temperature is higher than the phase transition temperature of the nickel-titanium shape memory alloy, and has a cylinder diameter slightly larger than the cable core diameter when the temperature is lower than the phase transition temperature of the nickel-titanium shape memory alloy.

4. A crimp-type cable connector based on nickel-titanium shape memory alloy according to claim 3, characterized in that: The connecting tube has a cylinder diameter that is 0.1-0.2 mm smaller than the cable core diameter when the temperature is higher than the phase transition temperature of the nickel-titanium shape memory alloy, and has a cylinder diameter that is 2-3 mm larger than the cable core diameter when the temperature is lower than the phase transition temperature of the nickel-titanium shape memory alloy.

5. A crimp-type cable connector based on nickel-titanium shape memory alloy according to claim 1, characterized in that: The copper lining is a copper strip, a plurality of which are symmetrically arranged and adhered to the inner wall of the connecting pipe using conductive glue.

6. A crimp-type cable connector based on nickel-titanium shape memory alloy according to claim 5, characterized in that: The conductive adhesive is a mixture of resin as a matrix and conductive powder as a filler.

7. A crimping type cable connection method based on nickel-titanium shape memory alloy, using the connector according to any one of claims 1 to 6, characterized in that: The specific steps are as follows: Step 1: Pretreatment of the cable: strip the insulation layer of the cable end to expose the cable core; clean the surface of the cable core to ensure there is no oxide layer or dirt; Step 2, installing the connector: cold-expand the connection tube at a temperature lower than the phase transition temperature of the nickel-titanium shape memory alloy so that its inner diameter is larger than the outer diameter of the cable conductor; and the cold-expanded connector is put on the cable conductor; Step 3, heating and tightening: Use a heating device to heat the connector to a temperature higher than the phase change temperature of the nickel-titanium shape memory alloy, so that it can restore the preset crimping shape and tightly wrap the cable conductor; Step 4: Cooling and shaping: After stopping heating, the connector is cooled to room temperature, the crimping shape is maintained, and the crimping quality is checked to see if it meets the requirements; Step 5: Clean the connector and cover the outside of the connector with insulating material to complete the cable connection.

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