High-roundness high-voltage shielding thin-wall locomotive cable and preparation method thereof

Abstract

The invention relates to the technical field of wires and cables, in particular to a high-roundness high-voltage shielding thin-wall locomotive cable and a preparation method thereof, and the high-roundness high-voltage shielding thin-wall locomotive cable comprises a plurality of cable cores which comprise power cable cores and / or control cable cores; the cable comprises a cable core, a plurality of cable core sleeves, the cable core sleeves are extruded on the outer wall of the cable core or are independently extruded and formed, and the cable core sleeves are extruded by a mold after being extruded to form a hexagon with the section shape being a preset size or a local outline spliced with the hexagon, so that the plurality of cable core sleeves can be mutually spliced to form a cable core group with the preset section shape. According to the invention, the cable core sleeve is designed into a hexagonal structure which can be seamlessly spliced, so that the high filling rate of the cross section of the cable core and the surface contact mode between the cable core units are realized, the independent cable cores can be integrated into a whole, the torsion resistance, impact resistance and bending deformation resistance of the cable are enhanced, and the service life of the cable is prolonged. The problems of insulation layer damage and structure out-of-roundness caused by internal stress concentration of a multi-core thin-wall cable are solved.

Description

Technical Field

[0001] This invention relates to the field of wire and cable technology, and more specifically to a high-roundness, high-voltage shielded, thin-walled locomotive cable and its preparation method. Background Technology

[0002] In the field of railway locomotives and EMUs, with the continuous improvement of train intelligence and lightweight design, the electrical equipment inside the carriages is becoming increasingly dense, and the control systems are becoming more complex. This trend has led to a significant increase in the number of cores in the cables required for vehicle wiring to meet the transmission needs of power distribution, control signals, and data communication. At the same time, due to the extremely limited installation space inside the car body, almost stringent requirements have been placed on the miniaturization, lightweighting, and high reliability of cables. Against this backdrop, thin-walled cables, which can effectively reduce outer diameter and weight while ensuring electrical performance, have become the mainstream choice for locomotive and rolling stock cables.

[0003] However, in the traditional process of stranding dozens (e.g., up to 60 cores) of independent thin-walled insulated wire cores into a single cable core, it is necessary to accurately calculate the stranding pitch, stranding direction, and amount and shape of filler material for each wire core in order to compensate for the unavoidable geometric gaps between the wire cores. Moreover, the more cores there are, the more complex the design and process calculation of the stranding structure becomes, and it is difficult to guarantee the consistency between theoretical calculations and actual cable formation results.

[0004] Meanwhile, while the thin-walled structure gives the cable its lightweight and slender characteristics, it also makes its core relatively weak. In the complex multi-core stranding process, the round cores mainly make point or line contact, resulting in poor structural stability. When the cable is subjected to mechanical stresses such as vibration and bending during locomotive operation, the internal cores are prone to relative displacement and slippage. This may not only cause the cable core structure to become loose and out of round, but also pose a risk of stress concentration in the local thin-walled insulation layer, leading to damage and threatening electrical safety. Summary of the Invention

[0005] To address the technical problems existing in existing thin-walled locomotive cables, according to a first aspect of the present invention, a high-roundness high-voltage shielded thin-walled locomotive cable is proposed, comprising: Multiple conductors, including power conductors and / or control conductors; Multiple core sleeves are extruded onto the outer wall of the core or extruded independently, and after extrusion, they are pressed by a die to form a hexagon with a predetermined cross-sectional shape or a partial outline that is spliced ​​with the hexagon, so that multiple core sleeves can be spliced ​​together to form a core group with a predetermined cross-sectional shape. Multiple filler strips are provided, each filler strip having a first side surface and a second side surface. The first side surface of the filler strip has a contour that matches the outer wall of the core assembly, and the second side surface of the filler strip has an arc surface that matches the outer tangent circle contour of the core assembly. After the multiple filler strips fill the gaps on the outside of the core assembly, they are twisted together with the core assembly and wrapped and fixed by the wrapping tape layer to form a cable core with a circular cross-section. A braided shielding layer is wrapped around the outer wall of the cable core; The outer sheath is extruded onto the outer wall of the braided shielding layer; The core assembly includes a first core sleeve of a first size and multiple second core sleeves of a second size, or the core assembly includes only multiple second core sleeves of a second size. The cross-sectional shape of the first core sleeve can be formed by splicing multiple second core sleeves. The multiple core sleeves are in surface-to-surface contact with each other, and the core sleeves and the filler strip are in surface-to-surface contact with each other, so that the cable core forms a dense cross-section.

[0006] Preferably, the power core includes a first conductor, a first insulation layer, and a first shielding layer, and the control core includes a twisted pair and a second shielding layer covering the twisted pair.

[0007] Preferably, the first shielding layer includes a copper strip shielding layer longitudinally wrapped around the first insulation layer or a copper wire loosely wound structure layer loosely wound around the first insulation layer, and the second shielding layer includes a copper strip shielding layer longitudinally wrapped around the outer wall of the twisted pair or a copper wire braided shielding layer woven around the twisted pair.

[0008] Preferably, the core sleeve includes an outer support layer and an inner semi-conductive shielding layer, wherein the support layer includes an irradiated cross-linked polyolefin support layer and the semi-conductive shielding layer includes a semi-conductive cross-linked polyolefin shielding layer.

[0009] Preferably, the support layer of the core sleeve is further provided with tensile cores, and at least two tensile cores are provided along the diagonal direction of the core sleeve, and the tensile cores include aramid fiber bundles.

[0010] Preferably, the core assembly includes a first core sleeve of a first size and a plurality of second core sleeves of a second size, wherein the plurality of second core sleeves are located outside the first core sleeve, and the plurality of second core sleeves form a predetermined gap with the wrapping tape layer, the gaps formed by the plurality of second core sleeves and the wrapping tape layer are of the same size, the first core sleeve is used to accommodate the power core, the plurality of second core sleeves are used to accommodate the control core, or some of the second core sleeves are hollow or solid structures.

[0011] Preferably, the core assembly includes only a plurality of second core sleeves of a second size, the plurality of second core sleeves being in surface-to-surface contact with each other, and the two or more adjacent second core sleeves on the outermost layer forming a gap of a predetermined shape, and the gaps of the plurality of predetermined shapes having the same size, the second core sleeves being used to accommodate power cores and / or control cores, or a portion of the second core sleeves having a hollow or solid structure.

[0012] Preferably, the outermost layer of the core group is a second core sleeve, and the number of the outermost second core sleeves is 6n, where n is a positive integer greater than 1. The outermost second core sleeve contains power cores and / or control cores and / or hollow structures and / or solid structures.

[0013] According to a second aspect of the present invention, a method for preparing a high-roundness, high-voltage shielded thin-walled locomotive cable as described above is provided, comprising the following steps: Step S1: Prepare the cores: Prepare an appropriate number of power cores and / or control cores as required; Step S2, Extruding and pressing to form a core sleeve: The core prepared in step S1 is passed through an extruder to extrude molten polymer material to form a core sleeve blank outside the core; or, a hollow or solid core sleeve blank is independently extruded; before the core sleeve blank is completely cooled and solidified, it is passed through a sizing die with a predetermined cross-sectional shape to extrude the blank into a core sleeve with a hexagonal cross-sectional shape of a predetermined size or a core sleeve with a partial contour spliced ​​with the hexagon of the predetermined size; Step S3: Constructing a core assembly: The core sleeves obtained in step S2 are spliced ​​together according to a preset arrangement rule, so that the core sleeves are in face-to-face contact to form a core assembly with a predetermined cross-sectional shape. Step S4, extruding filler strips and cabling: according to the core group, filler strips of a predetermined shape are extruded, and the core group obtained in step S3 is twisted together with multiple filler strips. The filler strips fill the gaps on the outermost side of the core group. Then, wrapping tape is used to wrap and fix the twisted structure to form a cable core with a circular cross-section. Step S5, Braided Shielding: The outer wall of the cable core obtained in step S4 is braided to form a braided shielding layer; Step S6, Extruding the outer sheath: An outer sheath is formed by extruding the braided shielding layer to form the locomotive cable.

[0014] Preferably, in step S2, the sizing die includes two pairs of pressure rollers. The first pair of pressure rollers is used to shape the upper and lower parts of the blank, and the second pair of pressure rollers is used to shape the left and right sides of the blank. The polymer material used when extruding the wire core sleeve blank is irradiated cross-linked polyolefin, the extruder head temperature is 175~195℃, and the die temperature is 165~185℃. After the blank passes through the sizing die, it immediately enters the cooling water tank for cooling and shaping.

[0015] Compared with the prior art, the high-voltage shielded thin-walled locomotive cable design proposed in this invention achieves a high filling rate of the cable core cross-section by designing the core sleeve as a hexagonal structure that can be seamlessly spliced. The surface contact mode between the core units can integrate independent cores into a whole, enhancing the cable's resistance to torsion, impact and bending deformation, thereby solving the problem of insulation layer damage and structural out-of-roundness caused by internal stress concentration in multi-core thin-walled cables. The high-voltage shielded thin-walled locomotive cable of the present invention, based on the same basic unit core group configuration scheme, allows for flexible integration of power cores, control cores and functional reserved cavities of different specifications according to requirements. This is beneficial to achieving the roundness of the cable cross section, while simplifying the design, manufacturing and material management of the cable, and reducing the reliance on complex stranding calculations and manual filling skills. Attached Figure Description

[0016] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings.

[0017] Figure 1 This is a schematic diagram of the first structure of the high roundness high voltage shielded thin-walled locomotive cable shown in this invention.

[0018] Figure 2 This is a schematic diagram of the second structure of the high roundness high voltage shielded thin-walled locomotive cable shown in this invention.

[0019] Figure 3 This is a schematic diagram of the mold extruding the first wire core sleeve according to the present invention.

[0020] Figure 4 This is a schematic diagram of the extrusion molding of the first wire core sleeve by the mold shown in this invention.

[0021] Figure 5 This is a schematic diagram of the mold extruding the second core sleeve according to the present invention.

[0022] Figure 6 This is a schematic diagram of the second wire core sleeve being extruded using the mold shown in this invention. Detailed Implementation

[0023] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0024] {Example 1} Combination Figure 1 and Figure 2 As shown, the high roundness high voltage shielded thin-walled locomotive cable of this embodiment includes multiple cores 10, multiple core sleeves 20, multiple filler strips 30, a braided shielding layer 50, and an outer sheath 60.

[0025] Optionally, depending on user requirements, the conductor 10 may include a power conductor 11 and / or a control conductor 12.

[0026] Preferably, the wire core 10 includes a power wire core 11 and a control wire core 12 to achieve integrated transmission of power distribution and control signals, meeting the needs of intensive wiring of the vehicle's electrical system.

[0027] Furthermore, the core sleeve 20 is extruded onto the outer wall of the core 10 or extruded independently, and after extrusion, it is pressed by a die to form a hexagon with a predetermined cross-sectional shape or a partial outline that is spliced ​​with the hexagon, so that multiple core sleeves 20 can be spliced ​​together to form a core group with a predetermined cross-sectional shape.

[0028] In this way, by regularizing the external shape of the core sleeve 20 into a hexagon, multiple core sleeves 20 can achieve seamless surface contact when spliced, making the internal structure of the cable core dense, which helps to ensure the roundness and structural stability of the cable and avoid damage to the thin-walled insulation layer caused by core sliding and squeezing.

[0029] Furthermore, in combination Figure 1 As shown in Figure 2, the filler strip 30 is configured to include a first side surface and a second side surface. The first side surface of the filler strip 30 has a contour that matches the outer wall of the core assembly, and the second side surface of the filler strip 30 is configured to have an arc surface that matches the outer tangent circle contour of the core assembly. After multiple filler strips 30 fill the gaps on the outside of the core assembly, they are twisted together with the core assembly and wrapped and fixed by the wrapping tape layer 40 to form a circular cross-section cable core.

[0030] This allows the filler strip 30 to accurately and stably fill the outermost gap, forming a rounded cable core cross-section together with the core assembly. This lays a solid foundation for the uniform coverage of the subsequent shielding layer and sheath, and effectively improves the bending performance and appearance consistency of the cable.

[0031] Furthermore, the braided shielding layer 50 is wrapped around the outer wall of the cable core, and the outer sheath 60 is extruded around the outer wall of the braided shielding layer 50.

[0032] The core assembly includes a first core sleeve 21 of a first size and multiple second core sleeves 22 of a second size, or the core assembly includes only multiple second core sleeves 22 of a second size. The cross-sectional shape of the first core sleeve 21 can be formed by splicing multiple second core sleeves 22. The multiple core sleeves 20 are in surface-to-surface contact with each other, and the core sleeves 20 and the filler strip 30 are in surface-to-surface contact with each other, so that the cable core forms a dense cross-section.

[0033] In this way, the core sleeves 20 and the core sleeves 20 and the filler strips 30 are in surface-to-surface contact, which improves the traditional point and line contact into a stable planar support. This is conducive to integrating multiple independent core units into a whole with unified mechanical properties, thereby improving the cable core's resistance to torsion and flattening, and can evenly distribute external stress, thus enhancing the long-term reliability of thin-walled cables in locomotive vibration environments.

[0034] In an optional embodiment, the core assembly includes only a plurality of second core sleeves 22 of a second size, the plurality of second core sleeves 22 being in surface-to-surface contact with each other, and the two or more adjacent second core sleeves 22 located on the outermost layer forming a gap of a predetermined shape, and the gaps of the plurality of predetermined shapes having the same size, the second core sleeves 22 being used to accommodate power cores 11 and / or control cores 12, or a portion of the second core sleeves 22 having a hollow or solid structure.

[0035] Thus, since all are spliced ​​using the same size second core sleeve 22, the manufacturing and assembly process can be simplified, the process versatility can be improved, and power cores, control cores or reserved cavities can be freely configured in the core sleeve according to actual needs, so as to realize the customization of cable functions.

[0036] Specifically, in combination Figure 1 As shown, the core assembly includes only seven second core sleeves 22, which contain three power cores 11 and four control cores 12, and the second core sleeves 22 are all the same size.

[0037] In an optional embodiment, the core assembly includes a first core sleeve 21 of a first size and a plurality of second core sleeves 22 of a second size, wherein the plurality of second core sleeves 22 are located outside the first core sleeve 21, and the plurality of second core sleeves 22 form a predetermined gap with the wrapping layer 40, the gaps formed by the plurality of second core sleeves 22 and the wrapping layer 40 are of the same size, the first core sleeve 21 is used to accommodate the power core 11, the plurality of second core sleeves 22 are used to accommodate the control core 12, or some of the second core sleeves 22 are hollow or solid structures.

[0038] Thus, the first core sleeve 21 in the center can be used to lay out the power core 11 with a larger cross-section to meet the high power transmission requirements, while the second core sleeve 22 in the periphery is used to lay out the control core 12 or as a reserved channel, which is suitable for integrated transmission scenarios with existing main power and complex branch control signals.

[0039] Specifically, in combination Figure 2 As shown, the core assembly includes a first core sleeve 21 and 12 second core sleeves 22. The first core sleeve 21 houses a power core 11 (compared to...). Figure 1 The power core 11 shown is thicker), and the control core 12 is set inside the second core sleeve 22. Each second core sleeve 22 is the same size.

[0040] In the above embodiments, the outermost layer of the core group is a second core sleeve 22, and the number of the outermost second core sleeves 22 is 6n, where n is a positive integer greater than 1. The outermost second core sleeve 22 contains a power core 11 and / or a control core 12 and / or a hollow structure and / or a solid structure.

[0041] Thus, the aforementioned hexagonal splicing method can achieve gapless filling of the cable core and form a highly stable structure, such as... Figure 1 and Figure 2 The structures shown can all form a regular external outline through the outermost 6n second core sleeves 22, making the specifications of the filler strips 30 uniform and simplifying the cable-making process.

[0042] In an optional embodiment, the power core 11 includes a first conductor 111, a first insulation layer 112, and a first shielding layer 113, and the control core 12 includes a twisted pair 121 and a second shielding layer 122 covering the twisted pair 121.

[0043] The first shielding layer 113 includes a copper strip shielding layer that is longitudinally wrapped around the first insulation layer 112 or a copper wire loosely wound structure layer that is loosely wound around the first insulation layer 112. The second shielding layer 122 includes a copper strip shielding layer that is longitudinally wrapped around the outer wall of the twisted pair 121 or a copper wire braided shielding layer that is woven around the twisted pair 121.

[0044] Thus, the outer wall of the power core 11 is shielded with copper tape or loosely wound with copper wire to achieve electric field homogenization and high voltage shielding, while the control core 12 is shielded with braided copper wire to achieve electromagnetic interference resistance and protect weak signals.

[0045] In an optional embodiment, the thickness of the first insulating layer 112 is 0.8~1.2mm, and it is made of irradiated cross-linked polyolefin material to ensure the dielectric strength and heat resistance of the insulating layer.

[0046] Furthermore, the core sleeve 20 includes an outer support layer and an inner semi-conductive shielding layer. The support layer includes a cross-linked polyolefin support layer, and the semi-conductive shielding layer includes a semi-conductive cross-linked polyolefin shielding layer.

[0047] In this way, the outer support layer can provide the main mechanical protection and structural shaping for the wire core, while the inner semi-conductive shielding layer can make good contact with the shielding layer of the wire core to form a smooth equipotential surface, effectively eliminating the risk of surface discharge and optimizing the electric field distribution.

[0048] In an optional embodiment, the support layer of the core sleeve 20 is further provided with tensile cores, and at least two tensile cores are provided along the diagonal direction of the core sleeve 20. The tensile cores include aramid fiber bundles.

[0049] Thus, embedding aramid fiber bundles along the diagonal direction as tensile cores can enhance the axial tensile strength of the core sleeve 20, allowing the tensile load borne by the cable during operation or installation to be transferred from the conductor and thin-walled insulation layer to the aramid fibers.

[0050] {Example 2} Combination Figure 1 ,as well as Figures 3 to 6 As shown, the method for preparing a high-roundness, high-voltage shielded, thin-walled locomotive cable according to the present invention includes the following steps: Step S1: Prepare the cores: Prepare an appropriate number of power cores 11 and / or control cores 12 as required; Step S2, Extruding and pressing to form a core sleeve: The core 10 prepared in step S1 is passed through an extruder to extrude molten polymer material to form a core sleeve 20 blank outside the core 10; or, a hollow or solid core sleeve 20 blank is independently extruded and formed; while the core sleeve 20 blank is not completely cooled and solidified, it is passed through a sizing die with a predetermined cross-sectional shape to extrude and form a core sleeve 20 with a hexagonal cross-sectional shape of a predetermined size or a core sleeve 20 with a partial contour spliced ​​with a hexagon of a predetermined size; Step S3: Constructing a core assembly: The core sleeves 20 obtained in step S2 are spliced ​​together according to a preset arrangement rule, so that the core sleeves 20 are in contact with each other to form a core assembly with a predetermined cross-sectional shape. Step S4, extruding filler strips 30 and cabling: according to the core group, extruding filler strips 30 of a predetermined shape, twisting the core group obtained in step S3 together with multiple filler strips 30, filling the gaps on the outermost side of the core group with filler strips 30, and then using wrapping tape to wrap and fix the twisted structure to form a cable core with a circular cross section. Step S5, Braided Shielding: The outer wall of the cable core obtained in step S4 is braided to form a braided shielding layer 50; Step S6, Extruding the outer sheath: Extruding the braided shielding layer 50 to form the outer sheath 60, thus forming the locomotive cable.

[0051] In this way, the extrusion and die pressing are continuously combined online to achieve efficient, precise and large-scale production of hexagonal core sleeves. Through the shaping process in step S2 and the connection of step S3, the initial roundness of the cable core is guaranteed, making subsequent processes simple and reliable, with high overall production efficiency and good product consistency.

[0052] In an optional embodiment, in step S2, the sizing die includes two pairs of pressure rollers. The first pair of pressure rollers is used to shape the upper and lower parts of the blank, and the second pair of pressure rollers is used to shape the left and right sides of the blank. The polymer material used when extruding the wire core sleeve 20 blank is irradiated cross-linked polyolefin. The extruder head temperature is 175~195℃, and the die temperature is 165~185℃. After the blank passes through the sizing die, it immediately enters the cooling water tank for cooling and shaping.

[0053] Combination Figure 3 and Figure 4 As shown, the sizing die for the first core sleeve 21 specifically includes a first pair of pressure rollers a120 and a second pair of pressure rollers a110. The surface of the first pair of pressure rollers a120 forms a zigzag surface 121, and the surface of the second pair of pressure rollers a110 forms a concave trapezoidal surface 111. When the first pair of pressure rollers a120 and the second pair of pressure rollers a110 roll synchronously on the surface of the blank, the compression of the zigzag surface 121 and the trapezoidal surface 111 forms a shape as shown in the figure. Figure 4 The first core sleeve 21 is shown.

[0054] Combination Figure 5 and Figure 6 As shown, the sizing die for the second core sleeve 22 specifically includes a first pair of pressure rollers b220 and a second pair of pressure rollers b210. The surface of the first pair of pressure rollers b220 forms a V-shaped concave surface 221, and the surface of the second pair of pressure rollers b210 is a flat surface 211. When the first pair of pressure rollers b220 and the second pair of pressure rollers b210 roll synchronously on the surface of the blank, the compression of the concave surface 221 and the flat surface 211 forms a shape as shown in the figure. Figure 6 The second core sleeve 22 is shown.

[0055] In this way, the sizing die uses two pairs of pressure rollers to extrude and shape the hot blank in steps and directions. Compared with the integral die sleeve, it has less resistance to the blank and more stable forming, which is especially suitable for the precision forming of thin-walled structures.

[0056] Furthermore, specific roller surface profiles can be designed for the different shapes of the first core sleeve 21 and the second core sleeve 22 to ensure the accuracy and consistency of the final product dimensions.

[0057] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A high-roundness, high-voltage shielded, thin-walled locomotive cable, characterized in that, include: Multiple conductors (10), the conductors (10) including power conductors (11) and / or control conductors (12). Multiple core sleeves (20) are extruded onto the outer wall of the core (10) or extruded independently, and after extrusion, they are pressed by a mold to form a hexagon with a predetermined cross-sectional shape or a partial outline that is spliced ​​with the hexagon, so that multiple core sleeves (20) can be spliced ​​together to form a core group with a predetermined cross-sectional shape. Multiple filler strips (30) are configured to include a first side surface and a second side surface. The first side surface of the filler strip (30) has a contour that is adapted to the outer wall of the core group. The second side surface of the filler strip (30) is configured to have an arc surface that is adapted to the outer tangent circle contour of the core group. After the multiple filler strips (30) fill the gaps on the outside of the core group, they are twisted together with the core group and wrapped and fixed by the wrapping tape layer (40) to form a cable core with a circular cross section. A braided shielding layer (50) is wrapped around the outer wall of the cable core; The outer sheath (60) is extruded onto the outer wall of the braided shielding layer (50); The core assembly includes a first core sleeve (21) of a first size and multiple second core sleeves (22) of a second size, or the core assembly includes only multiple second core sleeves (22) of a second size. The cross-sectional shape of the first core sleeve (21) can be formed by splicing multiple second core sleeves (22). The multiple core sleeves (20) are in surface-to-surface contact with each other, and the core sleeves (20) and the filler strip (30) are in surface-to-surface contact with each other, so that the cable core forms a dense cross-section.

2. The high roundness high-voltage shielded thin-walled locomotive cable according to claim 1, characterized in that, The power core (11) includes a first conductor (111), a first insulation layer (112) and a first shielding layer (113), and the control core (12) includes a twisted pair (121) and a second shielding layer (122) covering the twisted pair (121).

3. The high roundness high-voltage shielded thin-walled locomotive cable according to claim 2, characterized in that, The first shielding layer (113) includes a copper strip shielding layer that is longitudinally wrapped around the first insulation layer (112) or a copper wire loosely wound structure layer that is loosely wound around the first insulation layer (112). The second shielding layer (122) includes a copper strip shielding layer that is longitudinally wrapped around the outer wall of the twisted pair (121) or a copper wire braided shielding layer that is woven around the twisted pair (121).

4. The high roundness high-voltage shielded thin-walled locomotive cable according to any one of claims 1-3, characterized in that, The core sleeve (20) includes an outer support layer and an inner semi-conductive shielding layer. The support layer includes a cross-linked polyolefin support layer, and the semi-conductive shielding layer includes a semi-conductive cross-linked polyolefin shielding layer.

5. The high roundness high-voltage shielded thin-walled locomotive cable according to claim 4, characterized in that, The core sleeve (20) is further provided with a tensile core in the support layer. At least two tensile cores are provided along the diagonal direction of the core sleeve (20). The tensile cores include aramid fiber bundles.

6. The high roundness high-voltage shielded thin-walled locomotive cable according to claim 1, characterized in that, The core assembly includes a first core sleeve (21) of a first size and a plurality of second core sleeves (22) of a second size, wherein the plurality of second core sleeves (22) are located outside the first core sleeve (21), and the plurality of second core sleeves (22) form a predetermined gap with the wrapping tape layer (40), the gap size formed by the plurality of second core sleeves (22) and the wrapping tape layer (40) is the same, the first core sleeve (21) is used to accommodate the power core (11), the plurality of second core sleeves (22) are used to accommodate the control core (12), or some of the second core sleeves (22) are hollow or solid structures.

7. The high roundness high-voltage shielded thin-walled locomotive cable according to claim 1, characterized in that, The core assembly includes only a plurality of second core sleeves (22) of a second size, the plurality of second core sleeves (22) are in surface-to-surface contact with each other, and the two or more adjacent second core sleeves (22) located on the outermost layer form a gap of a predetermined shape, and the gaps of the plurality of predetermined shapes have the same size. The second core sleeves (22) are used to accommodate power cores (11) and / or control cores (12), or part of the second core sleeves (22) is a hollow or solid structure.

8. The high roundness high-voltage shielded thin-walled locomotive cable according to claim 1, characterized in that, The outermost layer of the core group is a second core sleeve (22), and the number of the outermost second core sleeves (22) is 6n, where n is a positive integer greater than 1. The outermost second core sleeve (22) contains a power core (11) and / or a control core (12) and / or a hollow structure and / or a solid structure.

9. The method for preparing a high-roundness high-voltage shielded thin-walled locomotive cable according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1: Prepare the cores: Prepare an appropriate number of power cores (11) and / or control cores (12) as required. Step S2, Extrusion and Compression Molding of Core Sheath: The core (10) prepared in step S1 is passed through an extruder to extrude molten polymer material to form a core sheath (20) blank outside the core (10); or, hollow or solid core sheath (20) blanks are extruded independently; before the core sheath (20) blank is completely cooled and solidified, it is passed through a sizing die with a predetermined cross-sectional shape to extrude the blank into a core sheath (20) with a predetermined hexagonal cross-sectional shape or a core sheath (20) with a partial contour spliced ​​with the predetermined hexagonal shape. Step S3: Constructing a core assembly: The core sleeves (20) obtained in step S2 are spliced ​​together according to a preset arrangement rule, so that the core sleeves (20) are in face-to-face contact to form a core assembly with a predetermined cross-sectional shape. Step S4, extruding filler strips (30) and cabling: according to the core group, extruding filler strips (30) of a predetermined shape, twisting the core group obtained in step S3 together with multiple filler strips (30), the filler strips (30) filling the gaps on the outermost side of the core group, and then using wrapping tape to wrap and fix the twisted structure to form a cable core with a circular cross section. Step S5, Braided shielding: The outer wall of the cable core obtained in step S4 is braided to form a braided shielding layer (50); Step S6, Extrusion of outer sheath: An outer sheath (60) is formed by extruding the braided shielding layer (50) to form the locomotive cable.

10. The method for preparing a high-roundness, high-voltage shielded, thin-walled locomotive cable according to claim 9, characterized in that, In step S2, the sizing die includes two pairs of pressure rollers. The first pair of pressure rollers is used to shape the upper and lower parts of the blank, and the second pair of pressure rollers is used to shape the left and right sides of the blank. The polymer material used when extruding the wire core sleeve (20) blank is irradiated cross-linked polyolefin. The extruder head temperature is 175~195℃, and the die temperature is 165~185℃. After the blank passes through the sizing die, it immediately enters the cooling water tank for cooling and shaping.

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