A manufacturing method for a polypropylene cable terminal at 35 kV and below and a polypropylene cable terminal

Abstract

The present invention discloses a method for manufacturing a 35kV and below polypropylene cable terminal and a polypropylene cable terminal, the method comprising: stripping the cable end to expose the cable conductor and the cable insulation layer; winding the polypropylene insulation tape back and forth from the cut of the insulation shielding layer to the cable conductor for multiple times; putting a stress cone sleeve on the outside of the insulation shielding layer and the polypropylene insulation tape; then winding the polypropylene insulation tape back and forth from the insulation shielding layer to the cable conductor on the outside of the stress cone to a shuttle shape; heating and heat-insulating the polypropylene insulation tape, welding the cable insulation layer, the insulation shielding layer, the stress cone and the polypropylene insulation tape into one; installing a multi-umbrella-shaped rubber sleeve and a cable terminal. The polypropylene cable terminal obtained by the above method can remove the sliding surface between the cable accessories and the cable end, solving the problem of discharge caused by the appearance of air gaps on the sliding surface due to the decrease in adhesion and the problem of the electrical performance of the cable accessories decreasing due to aging in the later stage.

Description

Technical Field

[0001] The present invention relates to the technical field of cable installation, and particularly relates to a method for manufacturing a polypropylene cable terminal with a voltage of 35 kV or below and a polypropylene cable terminal. Background Art

[0002] Cross-linked polyethylene is widely used in current power cable materials due to its good electrical properties and heat resistance. However, when the cross-linked polyethylene cable reaches the end of its service life, due to its stable molecular structure and being a thermosetting material, it is difficult to degrade or recycle, which has an adverse impact on the environment. Therefore, environmentally friendly polypropylene cables have been applied, and the related cable accessory installation technology has also become the focus of research.

[0003] Currently, cold-shrink prefabricated rubber accessories are used to manufacture polypropylene cable terminals. They are prefabricated in the factory and then, through an expanding technology, a drawable expanding cylinder is used to expand their inner diameter, facilitating the fitting of the cold-shrink prefabricated rubber accessories onto the cable end during on-site use. Due to the certain elasticity of the cold-shrink prefabricated rubber accessories, they can fit onto the cable end. There is a rubber stress cone inside the cold-shrink prefabricated rubber accessory, which fits with the outer semi-conductive layer cut of the cable, and can equalize the concentrated electric field at the cut, avoiding cable operation failures caused by electric field concentration. The polypropylene cable terminals manufactured by the prior art have the following deficiencies:

[0004] When the cold-shrink prefabricated rubber accessory is in use, it fits onto the cable end, and there is a sliding surface between the cold-shrink prefabricated rubber accessory and the cable end. If other impurities such as conductive dust are left on this sliding surface during the installation of the cold-shrink prefabricated rubber accessory, the polypropylene cable terminal is likely to gradually generate creepage traces at the outer semi-conductive cut of the cable during long-term operation, ultimately leading to cable failures. At the same time, since the lifespan of the cold-shrink prefabricated rubber accessory is shorter than that of the cable, especially outdoors, it is more easily affected by various radiations, resulting in easier aging of the cold-shrink prefabricated rubber accessory. Power cable maintenance personnel need to regularly replace the cable accessories that have been in operation for a long time. If the replacement is not timely, after the cold-shrink prefabricated rubber accessory ages, its electrical performance deteriorates and it is prone to deformation, causing insufficient adhesion force at the sliding surface, and the cold-shrink prefabricated rubber accessory will slide, leading to cable failures, and its maintenance cost is relatively high. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned existing problems, and provide a method for manufacturing a polypropylene cable terminal with a voltage of 35 kV or below. The polypropylene cable terminal obtained by the above manufacturing method can remove the sliding surface between the cable accessory and the cable end, avoid the phenomenon of creepage traces generated at the outer semi-conductive cut of the cable, solve the problem of discharge caused by air gaps appearing at the sliding surface due to the decrease in adhesion force, and solve the problem of the deterioration of the electrical performance of the cable accessory due to its aging in the later stage, and can effectively reduce the later maintenance cost.

[0006] Another object of the present invention is to provide a polypropylene cable terminal produced by a manufacturing method for polypropylene cable terminals of 35 kV and below.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] A manufacturing method for polypropylene cable terminals of 35 kV and below, comprising the following steps:

[0009] (1) Cable stripping pretreatment:

[0010] Perform a stripping operation on the cable end to expose the cable conductor and the cable insulation layer at the cable end. The material of the cable insulation layer is polypropylene;

[0011] (2) Cable and stress cone winding treatment:

[0012] (2.1) Wind the polypropylene insulating tape back and forth from the cut of the insulation shield layer towards the cable conductor for multiple times, so as to cover the cut of the insulation shield layer and the cable insulation layer near the cut with the polypropylene insulating tape;

[0013] (2.2) Fit the stress cone on the outside of the insulation shield layer and the polypropylene insulating tape;

[0014] (2.3) Then wind the polypropylene insulating tape back and forth from the insulation shield layer towards the cable conductor on the outside of the stress cone until it forms a spindle shape; thus covering the insulation shield layer, the stress cone and the cable insulation layer with the polypropylene insulating tape;

[0015] (3) Cable end heating and fusion welding treatment:

[0016] Heat and keep warm the spindle-shaped polypropylene insulating tape, and fuse the cable insulation layer, the insulation shield layer, the stress cone and the polypropylene insulating tape into one body; the polypropylene insulating tape forms a restored insulation layer after melting;

[0017] (4) Installation of the multi-umbrella rubber sleeve and the cable terminal:

[0018] Install the multi-umbrella rubber sleeve, and the multi-umbrella rubber sleeve covers the outside of the insulation shield layer, the restored insulation layer and the cable insulation layer; install the cable terminal at the end of the cable conductor.

[0019] A preferred embodiment of the present invention, wherein in step (1), the specific steps of performing the stripping operation on the cable end are:

[0020] Remove the outer structure at the end of the cable to expose the insulation shielding layer; sequentially remove a part of the insulation shielding layer and the cable insulation layer to expose the cable conductor and the cable insulation layer; the outer structure includes a cable outer sheath and a metal sheath, and the metal sheath is located inside the cable outer sheath; after exposing the cable conductor and the cable insulation layer, chamfer the cut of the insulation shielding layer with a tool and perform a grinding treatment to make the cut of the insulation shielding layer round and without steps, and clean the cut.

[0021] Preferably, in step (2), the shape of the stress cone is a "son" shape, and the stress cone includes a straight segment and a curved arc segment; the straight segment of the stress cone covers the outside of the insulation shielding layer and the polypropylene insulating tape; the curved arc segment of the stress cone faces the cable conductor. The stress cone can equalize the electric field concentrated at the cut, avoiding cable operation failures caused by electric field concentration.

[0022] Preferably, the material of the insulation shielding layer contains polypropylene. In step (2), the stress cone is pre-fabricated in the factory. The insulation shielding layer material is extruded, heated, and divided through an extruder; the insulation shielding layer material is squeezed into the stress cone forming die, and the temperature of the stress cone is controlled by controlling the forming temperature. After cooling, the stress cone is taken out from the stress cone forming die. The purpose is that the stress cone is made of the insulation shielding layer material, that is, the materials of the insulation shielding layer and the stress cone are the same, both containing polypropylene. During the heat fusion treatment, since the material of the polypropylene insulating tape is polypropylene, the melted polypropylene insulating tape can be connected to the surface of the stress cone and the surface of the insulation shielding layer to form an integral body, preventing the existence of a sliding surface between the stress cone, the insulation shielding layer, and the cable insulation layer, and not damaging the original cable structure.

[0023] Preferably, between step (2) and step (3), the following steps are further included:

[0024] Installation of heating auxiliary materials at the cable end: Install heating auxiliary materials outside the polypropylene insulating tape wound to form a spindle-shaped structure, and install a temperature sensor on the heating auxiliary materials;

[0025] Between step (3) and step (4), the following steps are further included:

[0026] Removal of heating auxiliary materials at the cable end: After the heat preservation is completed, wait for the cable end to cool to room temperature, remove the heating auxiliary materials, and expose the restored insulation layer. By setting the heating auxiliary materials, it can protect the polypropylene insulating tape during heating, and the temperature sensor is used to detect the heating temperature of the cable end and monitor the heating temperature in real time.

[0027] Preferably, the heating auxiliary materials include a rubber soft film, tin foil, a polyimide tape, a silicone rubber heating tape, and a heat insulation cloth; when installing the heating auxiliary materials, the rubber soft film, tin foil, polyimide tape, silicone rubber heating tape, and heat insulation cloth are sequentially installed outside the polypropylene insulating strip material that forms a spindle-shaped structure after winding, and a temperature sensor is installed on the silicone rubber heating tape.

[0028] Preferably, after the heating auxiliary materials at the cable end are removed, the following steps are further included:

[0029] Treatment of the cable end shape: The surface of the restored insulating layer is polished in shape so that the restored insulating layer is evenly transitioned with the cable insulating layer and the insulating shielding layer, and the dust on the surface of the restored insulating layer is cleaned to keep the surface of the restored insulating layer clean.

[0030] Preferably, in step (3), a heating die is used to heat and keep warm the shuttle-shaped polypropylene insulating strip; the heating die includes an upper heating module and a lower heating module; both the upper heating module and the lower heating module include an inner die and an outer die, a die cavity is provided between the two inner dies, the die cavity is matched with the shuttle-shaped polypropylene insulating strip, and the outer die is arranged outside the inner die; a plurality of heating units are provided on the inner die, and the plurality of heating units are arranged along the outer contour of the shuttle-shaped polypropylene insulating strip; each heating unit independently controls its heating temperature. In the above structure, the plurality of heating units are arranged along the outer contour of the shuttle-shaped polypropylene insulating strip, that is, the plurality of heating units are arranged in a shuttle shape along the axis direction of the inner die, and the distance between each heating unit and the outer surface of the shuttle-shaped polypropylene insulating strip is the same. Since the polypropylene insulating strip is shuttle-shaped, the heating units are also arranged in a shuttle shape after arrangement; since the polypropylene insulating strip is of a shuttle-shaped structure and the stress cone is in a "son" shape, the radial thickness of the polypropylene insulating strip is different. If the temperature-controlled heating equipment in the prior art is used for heating, the polypropylene insulating strip will be unevenly heated in each area, resulting in disordered flow and uneven distribution after the polypropylene insulating strip melts, and the connection with the cable insulating layer, insulating shielding layer, and stress cone is not unified and the fusion is uneven. It is possible that the thicker part is not completely melted, and the thinner part transfers heat to the cable insulating layer, insulating shielding layer, or stress cone for a long time, resulting in the complete destruction of the structures of the cable insulating layer, insulating shielding layer, and stress cone, affecting the quality of the heat fusion connection and further affecting the quality of the polypropylene cable terminal; in the above structure, by providing a plurality of heating units, each heating unit can be independently controlled. The heating unit corresponding to the thinner part of the polypropylene insulating strip reduces the heating temperature, and the heating unit corresponding to the thicker part of the polypropylene insulating strip increases the heating temperature, so that the heat is evenly distributed in each area of the polypropylene insulating strip, and the polypropylene insulating strip flows evenly and is evenly distributed after melting, ensuring that the polypropylene insulation is integrated with the cable insulating layer, insulating shielding layer, and stress cone, and will not damage the structures of the cable insulating layer, insulating shielding layer, and stress cone, ensuring the quality of the heat fusion connection.

[0031] Preferably, an installation groove for installing a heating unit is provided on the inner mold, and a heat insulation member is provided between two adjacent heating units. The depth of the inner side surface of the heat insulation member extending inward is greater than the depth of the inner side surface of the installation groove extending inward; a heat conducting member is provided on the installation groove, and the heat conducting member is located inside the heating unit. In the above structure, when heating the spindle-shaped polypropylene insulating tape, the heating unit generates heat, and the heat is transferred to the inner mold through the heat conducting member and then transferred to the polypropylene insulating tape through the inner mold, so that the polypropylene insulating tape melts; in order to ensure that the heat is transferred along the radial inner side, by setting the heat insulation member, the axial transfer of heat is blocked, and the heat between each heating unit will not affect each other. The depth of the inner side surface of the heat insulation member extending inward is greater than the depth of the inner side surface of the installation groove extending inward, effectively blocking the axial transfer of heat on the inner mold, ensuring that the heat can be better transferred to the polypropylene insulating tape, and improving the melting effect and accuracy.

[0032] A polypropylene cable terminal is obtained by a manufacturing method of a polypropylene cable terminal with 35 kV or less.

[0033] The present invention has the following beneficial effects compared with the prior art:

[0034] 1. In the manufacturing method of a polypropylene cable terminal with 35 kV or less in the present invention, by using a polypropylene insulating tape consistent with the cable insulation layer material, through heating, the cable insulation layer, insulation shielding layer, stress cone and the polypropylene insulating tape are welded into one body, removing the sliding surface between the stress cone and the cable end in the cable accessory. The polypropylene insulating tape welds the stress cone, cable insulation layer and insulation shielding layer well together without damaging the original cable structure, avoiding the phenomenon of creepage traces at the outer semiconductive cut of the cable, and solving the problems of discharge caused by the air gap generated by the sliding surface due to the decrease in adhesion and the problem of discharge caused by the air gap generated by the sliding surface due to the decrease in adhesion.

[0035] 2. In the manufacturing method of a polypropylene cable terminal with 35 kV or less in the present invention, since the material of the polypropylene insulating tape is the same as that of the cable insulation layer at the cable end, both are polypropylene, its service life is high. Compared with thermosetting materials such as cross-linked polyethylene and rubber materials, it can be heated and used repeatedly, and its service life is the same as that of the cable itself; it can effectively reduce the later maintenance cost.

[0036] 3. In the method for manufacturing a 35kV and below polypropylene cable terminal of the present invention, the material of the polypropylene insulating tape is consistent with the material of the cable insulation layer in the cable end, and the insulating shielding layer and the stress cone material are the same, both containing polypropylene, so that the compatibility between the cable end and the polypropylene insulating tape is improved, and the compatible surfaces between the two are closely connected without gaps, avoiding discharge at the compatible surface when the cable is running. Compared with traditional cold-shrink prefabricated rubber accessories, its quality and operation safety are higher.

[0037] 4. A method for manufacturing a 35kV and below polypropylene cable terminal in the present invention, wherein the multi-umbrella-shaped rubber sleeve is an enhanced insulation structure with large and small umbrellas arranged alternately, and has no stress cone. It has good holding force and can be completely attached to the insulation surface of the restored fusion-type terminal, thereby improving the insulation performance of the fusion-type terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the structure after the cable end in the present invention is stripped.

[0039] Figure 2 It is a schematic diagram of the structure of the cable end after heating and welding treatment in the present invention.

[0040] Figure 3 It is a schematic diagram of the structure of the polypropylene cable terminal in the present invention.

[0041] Figure 4 It is a schematic diagram of the three-dimensional structure of the heating mold in the present invention when in use.

[0042] Figure 5 It is a schematic diagram of the three-dimensional structure of the heating mold in the present invention which hides the upper heating module or the lower heating module when in use.

[0043] Figure 6 It is a cross-sectional view of the heating mold in the present invention.

[0044] Figure 7 for Figure 6 A partial enlarged view of point A in the middle.

[0045] Figure 8 It is a schematic diagram of the structure of the heating unit and the heat conducting member in the present invention. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0047] Example 1

[0048] See also Figures 1 - 3, this embodiment discloses a manufacturing method of a polypropylene cable terminal 1 with a voltage of 35 kV and below, including the following steps:

[0049] (1) Cable stripping pretreatment:

[0050] Perform a stripping operation on the cable end to expose the cable conductor 11 and the cable insulation layer 12 at the cable end. The material of the cable insulation layer 12 is polypropylene; specifically:

[0051] Strip each layer structure at the cable end according to the process dimensions, remove the outer layer structure at the cable end to expose the insulation shielding layer 13; sequentially strip a part of the insulation shielding layer 13 and the cable insulation layer 12 according to the process dimensions to expose the cable conductor 11 and the cable insulation layer 12; chamfer and polish the cut edges of the insulation shielding layer 13 and the cable insulation layer 12 with a tool so that the cut edges of the insulation shielding layer 13 and the cable insulation layer 12 are round and have no steps, or only chamfer and polish the cut edge of the insulation shielding layer 13 with a tool so that the cut edge of the insulation shielding layer 13 is round and has no steps; clean the cut edge; the outer layer structure includes a cable outer sheath and a metal sheath, and the metal sheath is located inside the cable outer sheath.

[0052] (2) Winding treatment of the cable and the stress cone 14:

[0053] (2.1) Wind the polypropylene insulating tape back and forth 2-3 times from the cut of the insulation shielding layer 13 towards the cable conductor 11 in a semi-covered manner, so as to cover the cut of the insulation shielding layer 13 and the cable insulation layer 12 near the cut with the polypropylene insulating tape;

[0054] (2.2) Fit the stress cone 14 on the outside of the insulation shielding layer 13 and the polypropylene insulating tape;

[0055] (2.3) Then wind the polypropylene insulating tape back and forth from the insulation shielding layer 13 towards the cable conductor 11 on the outside of the stress cone 14 until it is spindle-shaped, that is, olive-shaped; thus covering the insulation shielding layer 13, the stress cone 14, and the cable insulation layer 12 with the polypropylene insulating tape.

[0056] (3) Installation of heating auxiliary materials at the cable end:

[0057] Install heating auxiliary materials on the outside of the polypropylene insulating tape formed into a spindle-shaped structure after winding, and install a temperature sensor on the heating auxiliary materials; by setting the heating auxiliary materials, protection can be provided during the heating of the polypropylene insulating tape, and the temperature sensor is used to detect the heating temperature at the cable end and monitor the heating temperature in real time.

[0058] (4) Heating and fusion welding treatment of the cable end:

[0059] Use a temperature control device to heat and keep warm the shuttle-shaped polypropylene insulating tape, and weld the cable insulation layer 12, the insulation shielding layer 13, and the stress cone 14 together with the polypropylene insulating tape; after the polypropylene insulating tape melts, a restored insulation layer 15 is formed.

[0060] (5) Removal of the heating auxiliary materials at the cable end:

[0061] After the heat preservation ends, wait for the cable end to cool to room temperature, remove the heating auxiliary materials, and expose the restored insulation layer 15.

[0062] (6) Treatment of the cable end shape:

[0063] Grind the surface of the restored insulation layer 15 so that the restored insulation layer 15 transitions evenly with the cable insulation layer 12 and the insulation shielding layer 13, clean the dust on the surface of the restored insulation layer 15, and keep the surface of the restored insulation layer 15 clean.

[0064] (7) Installation of the multi-umbrella rubber sleeve 16 and the cable terminal 17:

[0065] Install the multi-umbrella rubber sleeve 16 according to the process dimensions. The multi-umbrella rubber sleeve 16 covers the outside of the insulation shielding layer 13, the restored insulation layer 15, and the cable insulation layer 12; install the cable terminal 17 at the end of the cable conductor 11; complete the production of the polypropylene cable terminal 1.

[0066] See Figures 1 - 3 , in step (1), use 600-mesh sandpaper to polish the cut of the insulation shielding layer 13 and the cable insulation layer 12.

[0067] See Figures 1 - 3 , in step (2), the shape of the stress cone 14 is "r" shaped, which can also be called trumpet shaped. The stress cone 14 includes a straight segment and a curved arc segment, that is, the axial cross-sectional shape of the stress cone 14 is a straight line at one end and an arc curved along the outside at the other end; the straight segment of the stress cone 14 covers the outside of the insulation shielding layer 13 and the polypropylene insulating tape, and the curved arc segment of the stress cone 14 faces the cable conductor 11; the arc port (the port of the curved arc segment) of the stress cone 14 is the midpoint of the shuttle shape. The stress cone 14 can equalize the electric field concentrated at the cut and avoid cable operation failures caused by electric field concentration.

[0068] See Figures 1 - 3, the material of the insulation shielding layer 13 contains polypropylene. In step (2), the stress cone 14 is prefabricated in the factory. The material of the insulation shielding layer 13 is extruded, heated, and branched through an extruder; the material of the insulation shielding layer 13 is extruded into the stress cone forming die, and the temperature of the stress cone 14 is controlled by controlling the forming temperature. After cooling, the stress cone 14 is taken out from the stress cone forming die. The purpose is that the stress cone 14 is made of the material of the insulation shielding layer 13, that is, the materials of the insulation shielding layer 13 and the stress cone 14 are the same, both containing polypropylene. During the heat welding treatment, since the material of the polypropylene insulating tape is polypropylene, the melted polypropylene insulating tape can be connected to the surface of the stress cone 14 and the surface of the insulation shielding layer 13 to form an integral body, preventing a sliding surface between the stress cone 14, the insulation shielding layer 13, and the cable insulation layer 12, and not damaging the original cable structure.

[0069] See Figures 1 - 3 , in step (3), the heating auxiliary materials include a rubber soft film, tin foil, polyimide tape, silicone rubber heating tape, and heat insulation cloth; when installing the heating auxiliary materials, the rubber soft film, tin foil, polyimide tape, silicone rubber heating tape, and heat insulation cloth are sequentially installed outside the polypropylene insulating tape formed into a spindle shape after winding, and a temperature sensor is installed on the silicone rubber heating tape. In step (5), after the heat preservation is completed, when the cable end cools to room temperature, the heat insulation cloth, silicone rubber heating tape, polyimide tape, tin foil, rubber soft film and other heating auxiliary materials are sequentially removed to expose the restored insulation layer 15.

[0070] See Figures 1 - 3 , in step (6), the specific steps for shaping and polishing the surface of the restored insulation layer 15 are as follows: use 240-mesh sandpaper to shape and polish the surface of the restored insulation layer 15 so that the restored insulation layer 15 is evenly transitioned with the cable insulation layer 12 and the insulation shielding layer 13, that is, one end of the restored insulation layer 15 is evenly transitioned with the cable insulation layer 12, and the other end of the restored insulation layer 15 is evenly transitioned with the insulation shielding layer 13; and the overall shape of the restored insulation layer 15 is spindle-shaped, and then use 600-mesh sandpaper to polish the surface of the restored insulation layer 15 to remove the traces of the 240-mesh sandpaper and polish it smoothly.

[0071] See Figures 1 - 3 , in step (7), the specific steps for installing the cable terminal 17 at the end of the cable conductor 11 are as follows: put the cable terminal 17 on the cable conductor 11, select a suitable crimping die for crimping, and finally restore the rest of the cable structure.

[0072] See Figures 1 - 3In step (7), the multi-umbrella-shaped rubber sleeve 16 is an enhanced insulation structure with large and small umbrellas arranged alternately, and the stress-free cone 14 has a good clamping force and can be completely attached to the insulation surface of the restored fusion terminal, thereby improving the insulation performance of the fusion terminal.

[0073] Example 2

[0074] See also Figures 4 - 8; Other steps of the manufacturing method in this embodiment are the same as those in Embodiment 1. The difference is that in this embodiment, the two steps of installing the cable end heating auxiliary material and removing the cable end heating auxiliary material are not required. In the cable end heating and welding treatment step of step (4), a heating mold is used to heat and keep warm the spindle-shaped polypropylene insulating tape; the heating mold includes an upper heating module 2 and a lower heating module 3; both the upper heating module 2 and the lower heating module 3 include an inner mold 4 and an outer mold 5. A mold cavity 6 is provided between the two inner molds 4, and the mold cavity 6 cooperates with the spindle-shaped polypropylene insulating tape. The outer mold is arranged outside the inner mold 4; a plurality of heating units 7 are provided on the inner mold 4, and the plurality of heating units 7 are arranged along the outer contour of the spindle-shaped polypropylene insulating tape; each heating unit 7 independently controls its heating temperature.In the above structure, the upper heating module 2 and the lower heating module 3 are connected by bolts. When in use, the upper heating module 2 and the lower heating module 3 are covered on the outside of the polypropylene insulating tape of the shuttle structure, and then the upper heating module 2 and the lower heating module 3 are fixed by bolts. Specifically, the two ends of the upper heating module 2 and the lower heating module 3 are fixed by clamps, and the clamps are fixed to the ends of the cables by bolts. The polypropylene insulating tape of the shuttle structure is located in the mold cavity 6 between the two inner molds 4, and then the heating unit 7 is heated to realize the melting of the polypropylene insulating tape; after the polypropylene insulating tape is melted, a recovery insulating layer 1 is formed. 5; the outer mold 5 has a heat-insulating effect to ensure that heat will not be lost; multiple heating units 7 are arranged along the outer contour of the shuttle-shaped polypropylene insulating tape, that is, multiple heating units 7 are arranged in a shuttle shape along the axial direction of the inner mold 4, and each heating unit 7 is at the same distance from the outer surface of the shuttle-shaped polypropylene insulating tape. Since the polypropylene insulating tape is shuttle-shaped, the heating units 7 are also arranged in a shuttle shape; since the polypropylene insulating tape is a shuttle-shaped structure, and the stress cone 14 is in the shape of a "child", the radial thickness of the polypropylene insulating tape is different. If the temperature control heating device in the prior art is used The equipment is heated, resulting in uneven heating of various areas of the polypropylene insulating tape, so that after the polypropylene insulating tape is melted, the flow is disordered and unevenly distributed, and the connection with the cable insulation layer 12, the insulation shielding layer 13, and the stress cone 14 is not uniform, and the blending is uneven, which may cause the thicker part to not be completely melted, and the thinner part transfers heat to the cable insulation layer 12 or the insulation shielding layer 13 or the stress cone 14 for a long time, resulting in the complete destruction of the structure of the cable insulation layer 12, the insulation shielding layer 13, and the stress cone 14, affecting the quality of the heating welding, and then affecting the quality of the polypropylene cable terminal; in the above structure, By setting a plurality of heating units 7, each heating unit 7 can be independently controlled. The heating unit 7 corresponding to the polypropylene insulating tape with a smaller thickness reduces the heating temperature, and the heating unit 7 corresponding to the polypropylene insulating tape with a larger thickness increases the heating temperature, so that the heat in each area of ​​the polypropylene insulating tape is evenly distributed, and the polypropylene insulating tape flows and distributes evenly after melting, thereby ensuring that the polypropylene insulating tape is fused into one with the cable insulating layer 12, the insulating shielding layer 13, and the stress cone 14, and will not damage the structure of the cable insulating layer 12, the insulating shielding layer 13, and the stress cone 14, thereby ensuring the quality of the heating fusion.

[0075] See also Figures 4 - 8, an installation groove 41 for installing a heating unit 7 is provided on the inner mold 4, and a heat insulation member 8 is provided between two adjacent heating units 7. The depth of the inner side surface (the side close to the axis of the inner mold 4) of the heat insulation member 8 extending inward is greater than the depth of the inner side surface of the installation groove 41 extending inward, that is, the heat insulation member 8 is closer to the axis of the inner mold 4 than the installation groove 41; a heat conducting member 9 is provided on the installation groove 41, and the heat conducting member 9 is located inside the heating unit 7. In the above structure, when heating the spindle-shaped polypropylene insulating strip, the heating unit 7 generates heat, and the heat is transferred to the inner mold 4 through the heat conducting member 9, and then transferred to the polypropylene insulating strip through the inner mold 4, so that the polypropylene insulating strip melts; in order to ensure that the heat is transferred along the radial inner side, by setting the heat insulation member 8, the axial transfer of heat is blocked, and the heat between each heating unit 7 will not affect each other. The depth of the inner side surface of the heat insulation member 8 extending inward is greater than the depth of the inner side surface of the installation groove 41 extending inward, effectively blocking the axial transfer of heat on the inner mold 4, ensuring that the heat can be better transferred to the polypropylene insulating strip, and improving the melting effect and accuracy.

[0076] The heat conducting member 9 and the heating unit 7 are semi-circular. The temperature of the heating unit 7 can be controlled by voltage, and each heating unit 7 controls the voltage separately, so as to realize the separate control of heat.

[0077] Embodiment 3

[0078] See Figures 1 - 3 , this embodiment discloses a polypropylene cable terminal 1, and the polypropylene cable terminal 1 is manufactured by the manufacturing method of a 35 kV and below polypropylene cable terminal as described in Embodiment 1 or Embodiment 2.

[0079] See Figures 1 - 3 , the polypropylene cable terminal 1 includes a cable end portion and a cable accessory; the cable end portion is the connection end of the cable; it is a part of the cable; it includes a cable conductor 11, a cable insulation layer 12, and an insulation shielding layer 13; the cable insulation layer 12 is provided outside the cable conductor 11, and the insulation shielding layer 13 is provided outside the cable insulation layer 12. The cable end portion also includes an outer layer structure.

[0080] See Figures 1 - 3 , the cable accessory includes a stress cone 14, a restored insulation layer 15, a multi-umbrella rubber sleeve 16, and a cable terminal 17; the cable terminal 17 is installed at the end of the cable conductor 11; the restored insulation layer 15 is formed by melting the polypropylene insulating strip, and the cable insulation layer 12, the insulation shielding layer 13, the stress cone 14, and the restored insulation layer 15 are heat welded into one body; the multi-umbrella rubber sleeve 16 covers the insulation shielding layer 13, the restored insulation layer 15, and the cable insulation layer 12.

[0081] See Figures 1 - 3, in this embodiment, the insulating shielding layer 13 and the stress cone 14 are made of the same material, which includes polypropylene; the materials of the polypropylene insulating tape and the cable insulating layer 12 are both polypropylene. The material of the used polypropylene insulating tape is the same as that of the cable itself, which improves the compatibility between the cable insulating layer 12, the insulating shielding layer 13, the stress cone 14 and the restored insulating layer 15, making the compatible surfaces between them closely connected without gaps, and avoiding discharge at the compatible surfaces during cable operation. Compared with traditional cold-shrink prefabricated rubber accessories, its quality and operation safety are higher.

[0082] The above is the preferred embodiment of the present invention, but the embodiments of the present invention are not limited to the above content. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for manufacturing a 35kV and below polypropylene cable terminal, characterized in that: It includes the following steps: (1) Cable stripping pretreatment: Perform a stripping operation on the cable end to expose the cable conductor and the cable insulation layer at the cable end. The material of the cable insulation layer is polypropylene; (2) Cable and stress cone winding treatment: (2.1) Wind the polypropylene insulating tape back and forth from the cut of the insulation shield layer towards the cable conductor for multiple times; (2.2) Sheath the stress cone on the outside of the insulation shield layer and the polypropylene insulating tape; (2.3) Then wind the polypropylene insulating tape back and forth from the insulation shield layer towards the cable conductor on the outside of the stress cone until it forms a spindle shape; (3) Cable end heating and welding treatment: Heat and keep the temperature of the spindle-shaped polypropylene insulating tape, and weld the cable insulation layer, the insulation shield layer, the stress cone and the polypropylene insulating tape into one body; after the polypropylene insulating tape melts, it forms a restored insulation layer; (4) Installation of multi-umbrella rubber sleeve and cable terminal: Install the multi-umbrella rubber sleeve, and the multi-umbrella rubber sleeve covers the outside of the insulation shield layer, the restored insulation layer and the cable insulation layer; install the cable terminal at the end of the cable conductor; In step (3), a heating mold is used to heat and keep the temperature of the spindle-shaped polypropylene insulating tape; the heating mold includes an upper heating module and a lower heating module; both the upper heating module and the lower heating module include an inner mold and an outer mold. There is a mold cavity between the two inner molds, and the mold cavity cooperates with the spindle-shaped polypropylene insulating tape. The outer mold is arranged outside the inner mold; there are multiple heating units on the inner mold, and the multiple heating units are arranged along the outer contour of the spindle-shaped polypropylene insulating tape; each heating unit independently controls its heating temperature.

2. A method for manufacturing a 35kV and below polypropylene cable terminal according to claim 1, characterized in that: In step (1), the specific steps for performing the stripping operation on the cable end are: Strip the outer structure at the cable end to expose the insulation shield layer; sequentially strip a part of the insulation shield layer and the cable insulation layer to expose the cable conductor and the cable insulation layer; the outer structure includes a cable outer sheath and a metal sheath, and the metal sheath is located inside the cable outer sheath; After exposing the cable conductor and the cable insulation layer, chamfer and polish the cut of the insulation shield layer with a tool to make the cut of the insulation shield layer round and without steps, and clean the cut.

3. A method for manufacturing a 35kV and below polypropylene cable terminal according to claim 1, characterized in that: In step (2), the shape of the stress cone is "儿" shaped, and the stress cone includes a straight section and a curved arc section; the straight section of the stress cone covers the outside of the insulation shield layer and the polypropylene insulating tape, and the curved arc section of the stress cone faces the cable conductor.

4. A method for manufacturing a 35kV and below polypropylene cable terminal according to claim 1, characterized in that: The material of the insulation shield layer contains polypropylene. In step (2), the stress cone is prefabricated in the factory. The insulation shield layer material is extruded, heated and divided by an extruder; the insulation shield layer material is squeezed into the stress cone forming mold, and the temperature of the stress cone is controlled by controlling the forming temperature. After cooling, the stress cone is taken out from the stress cone forming mold.

5. The method for manufacturing a 35kV and below polypropylene cable terminal according to claim 1, characterized in that: Between step (2) and step (3), the following steps are also included: Installation of heating auxiliary materials at the cable end: Install heating auxiliary materials on the outside of the polypropylene insulating tape that forms a spindle shape after winding, and install a temperature sensor on the heating auxiliary materials; Between step (3) and step (4), the following steps are also included: Removal of heating auxiliary materials at the cable end: After the insulation is completed, wait for the cable end to cool to room temperature, remove the heating auxiliary materials, and expose the restored insulation layer.

6. A method for manufacturing a 35kV and below polypropylene cable terminal according to claim 5, characterized in that: The heating auxiliary materials include rubber soft film, tin foil, polyimide tape, silicone rubber heating tape and thermal insulation cloth; when installing the heating auxiliary materials, the rubber soft film, tin foil, polyimide tape, silicone rubber heating tape and thermal insulation cloth are installed in sequence on the outside of the polypropylene insulating tape that forms a shuttle-shaped structure after winding, and a temperature sensor is installed on the silicone rubber heating tape.

7. A method for manufacturing a 35kV and below polypropylene cable terminal according to claim 5, characterized in that: After the heating auxiliary materials at the cable end are removed, the following steps are also included: Cable end appearance treatment: Grind the surface of the restored insulation layer to make a uniform transition between the restored insulation layer and the cable insulation layer and the insulating shielding layer, clean the dust on the surface of the restored insulation layer, and keep the surface of the restored insulation layer clean.

8. The method for manufacturing a 35kV and below polypropylene cable terminal according to claim 1, characterized in that: The inner mold is provided with an installation groove for installing the heating unit, and a heat insulating member is provided between two adjacent heating units. The depth of the inner side surface of the heat insulating member extending inward is greater than the depth of the inner side surface of the installation groove extending inward; the installation groove is provided with a heat conductive member, and the heat conductive member is located on the inner side of the heating unit.

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