A stress cone structure for a cable termination

Abstract

The utility model provides a kind of stress cone structure of cable terminal head belongs to cable stress cone technical field, the stress cone structure of this cable terminal head, including conical body, inner liner and outer sheath, the conical body is hollow circular conical platform shape, the ratio of the major diameter and minor diameter of conical body is 4:1~2:1, the inner liner is set on the inner conical surface of conical body, and inner liner is made of silicone rubber material, the outer sheath is coated on the outer conical surface of conical body, and outer sheath is made of ethylene-propylene rubber material, it is characterized in that, the inner conical surface of conical body is evenly distributed with multiple spiral ridges along axial direction, the spiral angle of spiral ridge is 15~30 °, each spiral ridge extends from the minor end to the major end of conical body, the inner liner is embedded in the spiral groove formed between adjacent two spiral ridges, and the outer sheath is tightly combined with the outer conical surface of conical body by vulcanization process.

Description

Technical Field

[0001] This utility model belongs to the field of cable stress cone technology, and more specifically, relates to a stress cone structure for a cable termination. Background Technology

[0002] Cable terminations are critical components in power cable systems, used to connect cables to electrical equipment or overhead lines. The stress cone structure, as a core component of the cable termination, primarily functions to smoothly transition the electric field distribution at the cable termination location from a radial distribution inside the cable to an axial distribution outside, preventing insulation breakdown caused by electric field concentration. During long-term operation of power cables, the stress cone structure needs to withstand the heat generated by the load current and the cyclic effects of thermal expansion and contraction caused by changes in ambient temperature. It also needs to withstand mechanical vibrations and stresses during cable laying and operation. Existing stress cone structures typically employ a simple superposition of a conical body and an inner lining layer. The inner lining layer is bonded to the conical body using adhesives or mechanical compression. This bonding method is effective during the initial operation of the cable. While the existing adhesive can generally meet performance requirements, as operating time increases, the adhesive will fail due to aging, and the mechanical clamping force will weaken due to material creep. This can lead to slippage or detachment between the inner liner and the conical body. Once the inner liner shifts, it will disrupt the original electric field distribution design, causing a sharp increase in local electric field strength, forming a weak point in the insulation, which may eventually lead to a breakdown accident. To solve this problem, existing technologies have attempted to increase the amount of adhesive or increase the clamping force, but these methods are only temporary solutions and cannot fundamentally solve the problem of insufficient bonding strength between the inner liner and the conical body. Therefore, there is an urgent need for a new type of stress cone structure that can achieve a firm and reliable bond between the inner liner and the conical body, ensuring the long-term safe and stable operation of the cable termination. Utility Model Content

[0003] In view of this, the present invention provides a stress cone structure for cable terminations, which can solve the problem that the bonding strength between the inner lining and the cone-shaped body in the existing stress cone structure of cable terminations is insufficient. During long-term operation of the cable, the inner lining is prone to slippage or detachment due to thermal expansion and contraction cycles and mechanical vibration, which causes electric field distribution distortion and excessively high local electric field intensity, ultimately leading to insulation breakdown accidents and seriously threatening the safe and stable operation of the power system.

[0004] This utility model is implemented as follows:

[0005] This utility model provides a stress cone structure for cable termination heads, used to achieve uniform electric field distribution at cable termination positions. It includes a conical body, an inner liner, and an outer sheath. The conical body is a hollow frustum-shaped cone with a large-end diameter to small-end diameter ratio of 4:1 to 2:1. The inner liner is disposed on the inner conical surface of the conical body and is made of silicone rubber. The outer sheath covers the outer conical surface of the conical body and is made of EPDM rubber. Multiple spiral ridges are evenly distributed axially on the inner conical surface of the conical body, with a helix angle of 15° to 30°. Each spiral ridge extends from the small end to the large end of the conical body. The inner liner is embedded in a spiral groove formed between adjacent spiral ridges. The outer sheath is tightly bonded to the outer conical surface of the conical body through a vulcanization process.

[0006] The technical effects of the stress cone structure for cable termination provided by this utility model are as follows: By setting multiple spiral ridges evenly distributed along the axial direction on the inner conical surface of the conical body, and embedding the inner lining layer into the spiral groove between adjacent spiral ridges, the contact area and mechanical interlocking force between the inner lining layer and the conical body can be significantly increased, effectively preventing the inner lining layer from slipping or falling off due to thermal expansion and contraction during cable operation. At the same time, the special structure of the spiral ridges makes the electric field distribution more uniform, avoiding the risk of insulation breakdown caused by local electric field concentration. The outer sheath is tightly bonded to the conical body through a vulcanization process, further enhancing the overall sealing performance and mechanical strength.

[0007] Based on the above technical solution, the stress cone structure of the cable termination head of this utility model can be further improved as follows:

[0008] The spiral ridge has a trapezoidal cross-section, with the upper base width being smaller than the lower base width, and the angle between the two sides of the trapezoid and the inner conical surface of the conical body being 60° to 80°.

[0009] The beneficial effects of adopting the above-mentioned improved scheme are as follows: The spiral ridge adopts a trapezoidal cross-section design, with the upper base width being smaller than the lower base width, making the spiral groove a wedge-shaped structure that is narrower at the top and wider at the bottom. When the inner lining is embedded in the spiral groove, it will form a self-locking effect. Even when the cable is subjected to axial tension or torsional torque, the inner lining is not easy to come out of the spiral groove. A specific angle is set between the trapezoidal waist and the inner conical surface, which not only ensures sufficient mechanical strength but also avoids stress concentration, effectively improving the long-term reliability and service life of the stress cone structure.

[0010] Furthermore, an annular boss is provided on the large end face of the conical body. The inner diameter of the annular boss is coaxially set with the inner diameter of the large end of the conical body, and the height of the annular boss is 1 / 10 to 1 / 5 of the axial length of the conical body.

[0011] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the annular boss on the large end face of the conical body can provide stable support and positioning reference for the connection of the cable terminal head with other electrical equipment. The annular boss is coaxial with the inner diameter of the large end, which ensures the alignment accuracy during installation and avoids uneven stress distribution caused by installation deviation. The height of the annular boss is controlled within a reasonable range, which not only meets the mechanical strength requirements, but also does not excessively increase the amount of material used and the overall weight, which helps to reduce manufacturing costs and simplify installation operations.

[0012] Furthermore, the thickness of the inner lining layer gradually increases from the small end to the large end along the axial direction of the conical body, and the ratio of the inner lining layer thickness at the small end to the inner lining layer thickness at the large end is 1:3 to 1:2.

[0013] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the design of the inner liner thickness gradually increasing from the small end to the large end along the axial direction is adapted to the electric field intensity distribution law at the cable terminal position. A thinner inner liner is used in the small end region where the electric field intensity is higher to ensure a smooth electric field transition, while a thicker inner liner is used in the large end region where the electric field intensity is lower to provide better mechanical protection. This gradual thickness design enables the electrical and mechanical properties of the stress cone structure to be coordinated and optimized, effectively avoiding the problem of local overheating or mechanical damage caused by unreasonable inner liner thickness.

[0014] Furthermore, the outer surface of the outer sheath is provided with multiple annular anti-slip patterns, which are evenly distributed along the axial direction of the conical body, and the distance between two adjacent annular anti-slip patterns is 3 to 5 times the width of the annular anti-slip pattern.

[0015] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: setting multiple equally spaced annular anti-slip patterns on the outer surface of the outer sheath can significantly increase the friction coefficient of the outer sheath surface, allowing installers to grip the stress cone structure more firmly when installing or maintaining cable terminals, preventing installation errors or personal injury caused by hand slippage. The spacing design of the annular anti-slip patterns has been optimized, ensuring good anti-slip effect while avoiding affecting the overall strength and sealing performance of the outer sheath due to excessively dense patterns.

[0016] Furthermore, the top of the spiral ridge is provided with an arc-shaped transition surface, the radius of curvature of which is 1 / 2 to 2 / 3 of the height of the spiral ridge. The arc-shaped transition surface is used to form a smooth contact with the inner lining layer.

[0017] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the top of the spiral ridge is provided with an arc-shaped transition surface, which eliminates the risk of sharp edges cutting and damaging the inner lining layer. The arc-shaped transition surface forms a smooth contact with the inner lining layer, making the contact stress distribution more uniform and avoiding the generation of stress concentration points. The radius of curvature of the arc-shaped transition surface is precisely calculated, which not only ensures good fit with the inner lining layer, but also maintains the mechanical strength that the spiral ridge should have. This design significantly improves the fatigue resistance of the inner lining layer and the reliability of the overall stress cone structure.

[0018] Furthermore, a circular positioning hole is provided on the small end face of the conical body. The geometric center of the circular positioning hole coincides with the axis of the conical body, and the depth of the circular positioning hole is 1 / 20 to 1 / 10 of the axial length of the conical body.

[0019] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: A circular positioning hole concentric with the axis is set on the small end face of the conical body, which provides a precise guiding effect for the insertion and positioning of the cable conductor, ensuring that the cable conductor can be accurately inserted along the axial direction of the stress cone structure, avoiding electric field distortion and mechanical stress concentration caused by insertion angle deviation. The depth of the circular positioning hole is controlled within a reasonable range, which not only meets the positioning function requirements, but also does not excessively weaken the mechanical strength of the small end of the conical body, which is conducive to improving the installation accuracy and electrical performance stability of the cable terminal.

[0020] Furthermore, the conical body is made of epoxy resin material, and the glass transition temperature of the epoxy resin material is higher than 120°C.

[0021] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: The conical body is made of epoxy resin material with a glass transition temperature higher than 120℃, which can ensure that the stress cone structure maintains stable mechanical and electrical properties within the normal operating temperature range of the cable. The epoxy resin material has excellent insulation properties and mechanical strength, as well as good heat aging resistance and chemical corrosion resistance. Even under long-term high temperature and harsh environmental conditions, the conical body will not soften, deform or deteriorate in performance, effectively ensuring the long-term safe and reliable operation of the cable terminal head.

[0022] Furthermore, the outer circumference of the annular boss is provided with a plurality of evenly distributed rectangular grooves, the length direction of the rectangular grooves being parallel to the axis of the conical body, and the depth of the rectangular grooves being 1 / 4 to 1 / 3 of the radial thickness of the annular boss.

[0023] The beneficial effects of adopting the above-mentioned improved scheme are as follows: multiple evenly distributed rectangular grooves are set on the outer circumference of the annular boss. These grooves are used to accommodate fixing clips or fasteners, so that the stress cone structure can achieve a quick and reliable mechanical connection with the external mounting bracket or protective device. The length direction of the rectangular groove is parallel to the axis, which ensures the axial positioning accuracy of the mounting part. The reasonable control of the groove depth not only ensures the embedding depth of the mounting part, but also avoids excessive weakening of the overall strength of the annular boss. This design simplifies the on-site installation process of cable termination and improves construction efficiency.

[0024] Furthermore, the inner liner and the sidewall of the spiral groove are tightly fitted by an interference fit. The outer contour dimension of the inner liner in its free state is larger than the inner contour dimension of the spiral groove, and the interference amount is 5% to 15% of the thickness of the inner liner.

[0025] The beneficial effects of adopting the above-mentioned improved scheme are as follows: The interference fit design between the inner liner and the spiral groove sidewall requires a certain pressure to be applied during the installation process to embed the inner liner into the spiral groove. After installation, the inner liner generates a continuous clamping force on the spiral groove sidewall. This prestressed state can effectively compensate for the dimensional changes of the inner liner when the temperature changes, and prevent loosening of the fit due to thermal expansion and contraction. The interference is controlled within the range of 5% to 15% of the thickness of the inner liner, which ensures sufficient contact pressure and avoids damage to the inner liner or the conical body due to excessive assembly stress.

[0026] Compared with existing technologies, the beneficial effects of the stress cone structure for cable terminations provided by this utility model are as follows: This utility model fundamentally solves the technical problem of insufficient bonding strength between the inner lining layer and the conical body by setting a spiral ridge on the inner conical surface of the conical body and embedding the inner lining layer into a spiral groove. The mechanical interlocking force formed by the spiral ridge, combined with the prestress generated by the interference fit, results in a robust and reliable integrated structure between the inner lining layer and the conical body, effectively resisting the effects of thermal expansion and contraction and mechanical vibration. The self-locking effect generated by the spiral ridge in the trapezoidal cross-section further enhances the stability of the structure. The inner lining layer thickness... The axial gradient design makes the electric field distribution more uniform and reasonable, eliminating the phenomenon of local electric field concentration. The outer sheath is tightly bonded to the conical body through a vulcanization process to form a complete sealed protective layer, effectively preventing the intrusion of moisture and contaminants. The design of the annular boss and circular positioning hole improves the installation accuracy and ease of operation. The excellent comprehensive performance of epoxy resin material ensures the long-term reliability of the stress cone structure. Compared with the existing technology, this utility model significantly improves the electrical performance and mechanical reliability of the cable terminal head, extends its service life, reduces maintenance costs, and provides a more reliable technical guarantee for the safe and stable operation of the power system. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a stress cone structure for a cable termination.

[0029] Figure 2 A bottom view of a stress cone structure for a cable termination;

[0030] Figure 3 This is a cross-sectional view of a stress cone structure for a cable termination.

[0031] The attached diagram lists the components represented by each number as follows:

[0032] 1. Conical body; 2. Inner lining; 3. Outer sheath; 4. Spiral ridge. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0034] like Figures 1-3 The diagram shows a first embodiment of a stress cone structure for a cable termination provided by this utility model. In this embodiment, it is used to install at the cable termination position to achieve uniform electric field distribution. It includes a conical body 1, an inner liner 2, and an outer sheath 3. The conical body is in the shape of a hollow frustum cone, and the ratio of the diameter of the large end to the diameter of the small end of the conical body is 4:1 to 2:1. The inner liner is disposed on the inner conical surface of the conical body and is made of silicone rubber. The outer sheath covers the outer conical surface of the conical body and is made of EPDM rubber. The inner conical surface of the conical body has multiple spiral ridges 4 evenly distributed axially. The spiral angle of the spiral ridges is 15° to 30°. Each spiral ridge extends from the small end to the large end of the conical body. The inner liner is embedded in the spiral groove formed between two adjacent spiral ridges. The outer sheath is tightly bonded to the outer conical surface of the conical body through a vulcanization process.

[0035] In the above technical solution, the cross-section of the spiral ridge is trapezoidal, the width of the upper base of the trapezoid is smaller than the width of the lower base, and the angle between the two waists of the trapezoid and the inner conical surface of the conical body is 60° to 80°.

[0036] Furthermore, in the above technical solution, an annular boss is provided on the large end face of the conical body. The inner diameter of the annular boss is coaxially set with the inner diameter of the large end of the conical body, and the height of the annular boss is 1 / 10 to 1 / 5 of the axial length of the conical body.

[0037] Furthermore, in the above technical solution, the thickness of the inner lining layer gradually increases from the small end to the large end along the axial direction of the conical body, and the ratio of the thickness of the inner lining layer at the small end to the thickness of the inner lining layer at the large end is 1:3 to 1:2.

[0038] Furthermore, in the above technical solution, the outer surface of the outer sheath is provided with multiple annular anti-slip patterns. The annular anti-slip patterns are evenly distributed along the axial direction of the conical body, and the distance between two adjacent annular anti-slip patterns is 3 to 5 times the width of the annular anti-slip pattern.

[0039] Furthermore, in the above technical solution, the top of the spiral ridge is provided with an arc-shaped transition surface, the radius of curvature of which is 1 / 2 to 2 / 3 of the height of the spiral ridge, and the arc-shaped transition surface is used to form a smooth contact with the inner lining layer.

[0040] Furthermore, in the above technical solution, a circular positioning hole is provided on the small end face of the conical body. The geometric center of the circular positioning hole coincides with the axis of the conical body, and the depth of the circular positioning hole is 1 / 20 to 1 / 10 of the axial length of the conical body.

[0041] Furthermore, in the above technical solution, the conical body is made of epoxy resin material, and the glass transition temperature of epoxy resin material is higher than 120°C.

[0042] Furthermore, in the above technical solution, the outer circumferential surface of the annular boss is provided with multiple evenly distributed rectangular grooves. The length direction of the rectangular grooves is parallel to the axis of the conical body, and the depth of the rectangular grooves is 1 / 4 to 1 / 3 of the radial thickness of the annular boss.

[0043] Furthermore, in the above technical solution, the inner liner and the sidewall of the spiral groove are tightly fitted by an interference fit. The outer contour dimension of the inner liner in the free state is larger than the inner contour dimension of the spiral groove, and the interference amount is 5% to 15% of the thickness of the inner liner.

[0044] The following is a specific embodiment 1 of this utility model: This embodiment provides a stress cone structure suitable for 10kV power cables. The cone-shaped body is made of bisphenol A type epoxy resin material, with 15% silica filler added to the epoxy resin to improve mechanical strength. The glass transition temperature is 135℃. The cone-shaped body is in the shape of a hollow frustum cone, with an outer diameter of 80mm at the large end, an inner diameter of 45mm at the large end, an outer diameter of 35mm at the small end, an inner diameter of 20mm at the small end, an axial length of 120mm, and a ratio of the diameter of the large end to the diameter of the small end of 2.29:1. Six spiral ridges are evenly distributed axially on the inner conical surface of the cone-shaped body. The spiral helix angle of the spiral ridges is 22°. Each spiral ridge... Extending from the small end to the large end, a complete spiral is formed. The cross-section of the spiral ridge is trapezoidal, with an upper base width of 3mm, a lower base width of 6mm, and a height of 4mm. The angle between the two sides of the trapezoid and the inner conical surface is 70°. The top of the spiral ridge has an arc-shaped transition surface with a radius of curvature of 2.5mm. The inner lining is made of silicone rubber with a Shore hardness of 60A and a breakdown field greater than 20kV / mm. The cross-sectional dimensions of the inner lining in its free state are 6.5mm wide and 4.3mm high. Compared with the inner contour dimensions of the spiral groove, the interference in the width direction is 0.5mm, which accounts for 11.6% of the thickness of the inner lining. The thickness of the inner lining along the axial direction of the conical body is... The thickness gradually increases from 3mm at the small end to 8mm at the large end, with a thickness ratio of 1:2.67. The outer sheath is made of EPDM rubber, with carbon black reinforcing agent and antioxidant added. The outer sheath is 5mm thick. The outer surface of the outer sheath has 8 annular anti-slip grooves, evenly spaced along the axial direction. Each anti-slip groove is 3mm wide and 2mm high, with a spacing of 12mm between adjacent grooves, four times the width of the groove. The large end of the conical body has an annular boss with an inner diameter of 45mm (the same as the large end's inner diameter), an outer diameter of 65mm, and a height of 10mm. Six rectangular grooves are evenly distributed on the outer circumference of the annular boss, each groove being 8mm long and 5mm wide. The cone-shaped body has a diameter of 20 mm and a depth of 3 mm, which is 30% of the radial thickness of the annular boss. A circular positioning hole with a diameter of 20 mm (the same as the inner diameter of the small end) and a depth of 8 mm is provided on the small end face of the cone-shaped body. The cone-shaped body is manufactured using a mold casting process. Epoxy resin is cured at 150°C for 4 hours, and after cooling, it is demolded to obtain the cone-shaped body. The inner lining is manufactured into a long strip using an extrusion molding process. The outer sheath is directly formed on the outer conical surface of the cone-shaped body using an injection molding process. The vulcanization temperature is 160°C, and the vulcanization time is 30 min. In this embodiment, the stress cone structure is installed at the terminal position of a 10kV cross-linked polyethylene cable. The cable conductor cross-sectional area is 240 mm², and the insulation layer thickness is 5 mm.After installation, the 5mm stress cone structure underwent a power frequency withstand voltage test at 35kV for 5 minutes. No breakdown or flashover occurred. After the cable was put into operation, the stress cone structure remained stable under changes in load current and ambient temperature. The inner lining did not slip or detach, the electric field distribution was uniform, and the insulation performance was good.

[0045] The following is another specific embodiment 2 of this utility model: This embodiment 2 is based on embodiment 1, increasing the number of spiral ridges from 6 to 8, adjusting the helix angle from 22° to 18°, correspondingly reducing the width of the spiral groove, adjusting the cross-sectional dimensions of the inner liner to a width of 4.8mm and a height of 4.3mm, keeping the interference fit at 0.5mm, and keeping other dimensional parameters of the conical body unchanged. This improvement further increases the contact area between the inner liner and the conical body, resulting in stronger mechanical interlocking force. It is particularly suitable for cable terminals where the installation location experiences significant vibration or needs to withstand large mechanical stress. Test results show that the stress cone structure with 8 spiral ridges exhibits an inner liner displacement of less than 0.1mm when subjected to an axial tensile force of 1000N, which is significantly better than the design with 6 spiral ridges. This embodiment has been successfully applied in rail transit traction power supply systems, effectively addressing cable vibration and mechanical impact caused by train start-stop.

[0046] The following is another specific embodiment 3 of this utility model: This embodiment 3 is based on embodiment 1, and a fine longitudinal groove is set at the bottom of the spiral groove between the spiral ridges on the inner conical surface of the conical body. The longitudinal groove is arranged along the axial direction of the conical body, with a depth of 1mm and a width of 1mm. Three longitudinal grooves are set at the bottom of each spiral groove. The longitudinal groove is used to accommodate excess inner lining material or install lubricant during the installation of the stress cone structure, avoiding local stress concentration caused by material accumulation. At the same time, the longitudinal groove can also provide buffer space for the small deformation of the inner lining during cable operation, further improving the stress cone structure's adaptability to temperature cycles. This embodiment is particularly suitable for areas with large diurnal temperature differences or significant seasonal temperature differences, and can effectively cope with frequent thermal expansion and contraction cycles. Test results show that after 500 temperature cycle tests, the contact pressure between the inner lining of the stress cone structure with longitudinal groove design and the conical body can still be maintained at more than 85% of the initial value, which is significantly better than the design without longitudinal groove.

[0047] Specifically, the principle of this utility model is as follows: This utility model adopts a structural design in which a spiral ridge is embedded and fitted with an inner liner. From a mechanical perspective, this achieves multiple constraints between the inner liner and the conical body. The spiral ridge is evenly distributed along the axial direction of the inner conical surface of the conical body, forming a continuous spiral guide groove. When the inner liner is embedded in the spiral groove, the spiral ridge exerts a bidirectional constraint on the inner liner in both the circumferential and radial directions. The circumferential constraint prevents the inner liner from rotating around the axis of the conical body, while the radial constraint prevents the inner liner from moving outward in the radial direction. The trapezoidal cross-section design of the spiral ridge makes the spiral groove wedge-shaped. After the inner liner is embedded, it forms a wedge-shaped self-locking mechanism. When the cable is subjected to axial tension, the normal pressure between the inner liner and the sidewall of the spiral groove increases with the increase of tension, generating greater frictional resistance and effectively preventing axial slippage of the inner liner. The interference fit design makes the size of the inner liner slightly larger than the size of the spiral groove in its free state. During installation, the inner liner needs to be compressed and deformed. After installation, the inner liner exerts a retaining force on the sidewall of the spiral groove. The continuous elastic clamping force, this prestressed state can compensate for the dimensional changes of the material when the temperature changes, ensuring that the inner liner and the conical body always maintain a tight contact. The axial gradient design of the inner liner thickness is based on the theoretical calculation results of the electric field distribution at the cable terminal. A thinner inner liner is used in the small end area with higher electric field strength, so that the electric field lines can transition smoothly. A thicker inner liner is used in the large end area with lower electric field strength, providing sufficient mechanical protection and insulation margin. The outer sheath undergoes a chemical cross-linking reaction with the conical body through a vulcanization process to form an inseparable integral structure, completely eliminating the possibility of moisture and contaminants penetrating from the interface. The high glass transition temperature of the epoxy resin material ensures that the conical body maintains a rigid state within the cable operating temperature range and will not soften or deform due to temperature rise, providing stable mechanical support for the entire stress cone structure. Through the comprehensive application of the above-mentioned multiple technical means, this utility model fundamentally solves the technical problem of insufficient bonding strength between the inner liner and the conical body.

[0048] The specific operation or use method of this utility model is as follows: First, select a stress cone structure of appropriate size according to the cable specifications. Remove the insulation layer of the cable terminal to the specified length according to the design requirements. Clean the surface of the cable conductor, removing the oxide layer and contaminants. Align the small end of the conical body of the stress cone structure with the end of the cable conductor, allowing the circular positioning hole to fit into the cable conductor. Slowly push the conical body in until the large end annular boss fits against the end face of the cable outer sheath. At this point, the spiral ridge on the inner conical surface of the conical body forms a gap with the surface of the cable insulation layer. Take an inner lining material that matches the spiral groove, align one end of the inner lining with the starting position of the spiral groove, and press it into the spiral groove one turn at a time along the spiral direction. Because the inner lining and the spiral groove are designed with an interference fit, a special tool is required for the pressing process. Apply uniform pressure to ensure the inner lining is fully embedded in the spiral groove and tightly adheres to the groove bottom and sidewalls. After the inner lining is installed, check the overlap position between each ring of inner lining to ensure the overlap length meets the design requirements. Fit the outer sheath onto the outer conical surface of the conical body. Use heating or chemical vulcanization to cause the outer sheath to cross-link with the surface of the conical body, forming an integrated sealed structure. Finally, install the fixing buckle in the rectangular groove of the annular boss to fix the stress cone structure to the cable terminal bracket, completing the installation of the entire cable terminal head. During cable operation, the stress cone structure requires no special maintenance, only periodic visual inspection to confirm that the outer sheath is free from damage and aging, and that the annular boss is firmly fixed. If any abnormalities are found, power should be cut off for repair and replacement of damaged parts.

Claims

1. A stress cone structure for a cable termination, used for installation at the cable termination position to achieve uniform electric field distribution, comprising a conical body, an inner liner, and an outer sheath, wherein the conical body is in the shape of a hollow frustum cone, the ratio of the diameter of the large end to the diameter of the small end of the conical body is 4:1 to 2:1, the inner liner is disposed on the inner conical surface of the conical body, the inner liner is made of silicone rubber, and the outer sheath covers the outer conical surface of the conical body, the outer sheath is made of EPDM rubber, characterized in that... The inner conical surface of the conical body has multiple spiral ridges evenly distributed along the axial direction. The spiral ridges have a spiral helix angle of 15° to 30°. Each spiral ridge extends from the small end to the large end of the conical body. The inner lining is embedded in the spiral groove formed between two adjacent spiral ridges. The outer sheath is tightly bonded to the outer conical surface of the conical body through a vulcanization process.

2. The stress cone structure of a cable termination head according to claim 1, characterized in that, The cross-section of the spiral ridge is trapezoidal, with the upper base width being smaller than the lower base width, and the angle between the two sides of the trapezoid and the inner conical surface of the conical body being 60° to 80°.

3. The stress cone structure of a cable termination head according to claim 2, characterized in that, The large end face of the conical body is provided with an annular boss. The inner diameter of the annular boss is coaxial with the inner diameter of the large end of the conical body. The height of the annular boss is 1 / 10 to 1 / 5 of the axial length of the conical body.

4. The stress cone structure of a cable termination head according to claim 3, characterized in that, The thickness of the inner lining layer gradually increases from the small end to the large end along the axial direction of the conical body, and the ratio of the thickness of the inner lining layer at the small end to the thickness of the inner lining layer at the large end is 1:3 to 1:

2.

5. The stress cone structure of a cable termination head according to claim 4, characterized in that, The outer surface of the outer sheath is provided with multiple annular anti-slip patterns. The annular anti-slip patterns are evenly distributed along the axial direction of the conical body, and the distance between two adjacent annular anti-slip patterns is 3 to 5 times the width of the annular anti-slip pattern.

6. The stress cone structure of a cable termination head according to claim 5, characterized in that, The top of the spiral ridge is provided with an arc-shaped transition surface. The radius of curvature of the arc-shaped transition surface is 1 / 2 to 2 / 3 of the height of the spiral ridge. The arc-shaped transition surface is used to form a smooth contact with the inner lining layer.

7. The stress cone structure of a cable termination head according to claim 6, characterized in that, A circular positioning hole is provided on the small end face of the conical body. The geometric center of the circular positioning hole coincides with the axis of the conical body, and the depth of the circular positioning hole is 1 / 20 to 1 / 10 of the axial length of the conical body.

8. The stress cone structure of a cable termination head according to claim 7, characterized in that, The conical body is made of epoxy resin material, and the glass transition temperature of epoxy resin material is higher than 120°C.

9. The stress cone structure of a cable termination head according to claim 8, characterized in that, The outer circumference of the annular boss is provided with a plurality of evenly distributed rectangular grooves. The length direction of the rectangular grooves is parallel to the axis of the conical body, and the depth of the rectangular grooves is 1 / 4 to 1 / 3 of the radial thickness of the annular boss.

10. The stress cone structure of a cable termination head according to claim 9, characterized in that, The inner liner and the sidewall of the spiral groove are tightly fitted by an interference fit. The outer contour dimension of the inner liner in the free state is larger than the inner contour dimension of the spiral groove, and the interference amount is 5% to 15% of the thickness of the inner liner.

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