CN111834958A - Single-core cross-linked power cable insulating joint of 500kV and below and manufacturing process - Google Patents
Single-core cross-linked power cable insulating joint of 500kV and below and manufacturing process Download PDFInfo
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- CN111834958A CN111834958A CN202010716891.6A CN202010716891A CN111834958A CN 111834958 A CN111834958 A CN 111834958A CN 202010716891 A CN202010716891 A CN 202010716891A CN 111834958 A CN111834958 A CN 111834958A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G1/00—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines
- H02G1/14—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for joining or terminating cables
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Abstract
A manufacturing process of single-core cross-linked power cable insulation joints of 500kV and below comprises the steps of heating an extrusion molding machine body mold, a supporting heating insert mold and an extrusion glue injection mold to an extrusion temperature of 90-105 ℃, starting a preheated plastic extruding machine, injecting glue into the extrusion molding machine body mold through the extrusion glue injection mold, and expanding a rubber elastic rubber pipe by the glue when the glue is filled in the whole extrusion molding machine body mold and flows out from a glue discharging opening; and heating the body mold and the support heating insert mold of the extrusion molding machine, heating the cable conductor at the joint, and performing rapid grafting and crosslinking reaction on the colloid under given conditions. The manufacturing process is convenient to operate, the manufactured insulating joint and the cable body can form equivalent connection characteristics, and the mechanical and electrical properties of the cable body are met; the insulating layer has good cross-linking with the original cable and other recovery layers, and the generation of a movable interface is avoided.
Description
Technical Field
The invention relates to the field of cable joints, in particular to an insulating joint of a single-core cross-linked power cable of 500kV or below and a manufacturing process thereof.
Background
With the development of urban construction, the application of power cables is becoming more and more extensive. The high-voltage single-core crosslinked cable generally comprises a metal conductor, a conductor shielding layer, an insulating shielding layer, a buffer layer, a metal sheath, an outer protective layer and the like. The cable can be considered as a primary winding of an air core transformer between the conductor and the metal sheath. When the conductor of the cable passes through alternating current, a part of magnetic lines of force generated around the conductor of the cable are hinged to the metal sheath, the metal sheath generates induced voltage, the magnitude of the induced voltage is in direct proportion to the length of a cable line and the current flowing through the conductor, when the cable is long, the induced voltage on the sheath is superposed to the extent of endangering personal safety, and when the line has short circuit fault, is subjected to operation overvoltage or lightning impact, high induced voltage can be formed on the shield, and even the insulation of the sheath can be punctured. At present, the method for reducing the induced voltage of the metal sheath of the single-core cable mostly adopts a cross interconnection grounding mode, namely, a single-core cable line is divided into three small sections or multiple sections of three with equal length, an insulating joint is arranged between every two small sections, and the three-phase outer shields at the insulating joint are connected in a transposition mode through a cross interconnection box by using a coaxial cable, so that the induced voltage on the line is reduced. However, the existing manufacturing process is complex, equivalent connection is not easily formed between the insulating joint and the cable body, mechanical and electrical properties of the cable body cannot be met, a movable interface is easy to generate and contains harmful factors such as micro air gaps, micro water, impurities and the like, interface polarization and air gap surface discharge are easily caused, and serious hidden danger is brought to power grid operation. Meanwhile, most wire cores of the existing insulated joints are mechanically connected, and the contact resistance at the connecting part is large, so that heating is easily caused; the forming device is also adopted to manufacture the insulating joint, but the existing forming device has the defects of complex internal structure, large volume and inconvenient operation, and a movable interface is easy to exist between the formed insulating joint and the insulation of the cable main body.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides an insulating joint of a single-core crosslinked power cable of 500kV or below and a manufacturing process thereof.
The technical scheme of the invention is as follows:
a manufacturing process of an insulating joint of a single-core cross-linked power cable of 500kV or below comprises the following steps:
1) selecting a semi-conductive shielding material to manufacture a partially-crosslinked horn-shaped geometric stress control cone in a factory;
2) selecting a crosslinkable polyethylene resin composition as a main insulating material of the joint;
3) stripping a cable conductor, a conductor shielding layer, a cable insulating layer, an insulating shielding layer, a metal sheath and an outer protective layer according to the process size; respectively sleeving an insulating copper shell, a heat-shrinkable tube, a partially cross-linked geometric stress control cone and an expanded rubber elastic sleeve on a cable; integrally welding the cable conductors at two ends by adopting a fusion welding mode to form a welding end, and processing the welding end until the size of the welding end is consistent with that of the cable conductor; adopting a semi-conductive belt or a semi-conductive pipe made of a semi-conductive shielding material to recover a conductor shielding layer, winding a layer of heat-resistant isolation film, installing a semi-heated mold and heating, raising the temperature to a set crosslinking temperature, synchronously and gradually tightening the mold in the temperature raising process, carrying out heat preservation and pressure maintaining for a certain time, naturally cooling to the ambient temperature, then carrying out mold removal, and carrying out shape modification treatment on the recovered joint conductor shielding layer until the joint conductor shielding layer is smooth and flat;
4) installing an extrusion glue injection mould to one end of the joint, wherein the extrusion glue injection mould is used for providing molten glue; contracting the rubber elastic sleeve to a joint position, wherein a rubber outlet of the extrusion rubber inlet mould is communicated with an inner side cavity of the rubber elastic sleeve; installing an extrusion molding machine body mold to the periphery of the joint and fixedly connecting the extrusion molding machine body mold with an extrusion glue injection mold, wherein the extrusion molding machine body mold consists of two symmetrical machine body half molds and forms a joint mold cavity; pushing the partially cross-linked geometric stress control cone to one end matched with the rubber elastic sleeve, pushing the support heating insert mold into a partially cross-linked geometric stress control cone socket groove, and then fixedly connecting the support heating insert mold with an extrusion molding machine body mold; the supporting heating insert mold consists of two symmetrical supporting heating insert half molds, each supporting heating insert half mold comprises a supporting horn section and a straight line section, and the supporting horn sections and the straight line sections are matched with the shapes of the partial cross-linking geometric stress control cones;
5) heating the extrusion molding machine body mold, the support heating insert mold and the extrusion glue injection mold to an extrusion temperature of 90-105 ℃, starting the preheated extruding machine, the crosslinkable polyethylene resin composite material forms flowable colloid after passing through an extruding machine, and then is injected into an extrusion molding machine body mould through an extrusion glue injection mould, when the colloid is filled in the whole die of the extrusion molding machine body and flows out from the colloid discharging port, the colloid fills up the rubber elastic rubber tube, because the elastic property of the rubber elastic sleeve compresses the internal colloid and the colloid has the expansion property under the action of the internal temperature of the extrusion molding machine body mold, the designed elastic rubber sleeve can provide stable internal pressure, because the rubber has certain heat resistance, the poor crosslinking caused by the overheating of the joint due to the direct heating of the colloid by the mold of the extrusion molding machine body can be avoided;
6) closing the extruding machine, heating the extrusion molding machine body mold and the support heating insert mold, heating the cable conductor at the joint, performing rapid grafting and crosslinking reaction on the colloid under the conditions of a given temperature of 145-.
Preferably, the semiconductive shielding material mainly comprises ethylene-vinyl acetate copolymer, conductive carbon black, antioxidant and crosslinking agent.
Preferably, the crosslinkable polyethylene resin composition mainly comprises a polyethylene resin, a chemical crosslinking agent, an antioxidant and a crosslinking promoter.
Preferably, the method further comprises a step 7) of removing all the dies and the rubber elastic sleeve after naturally cooling to room temperature, polishing and shaping the insulating layer of the insulating joint until the surface is smooth and flat, and covering the insulating layer with a stress control cone by 2-12mm to form an insulating section of the insulating shielding layer of the cable at two ends.
Preferably, the method further comprises the step 8) of uniformly coating the semi-conductive coating on the colloid from the fracture of the insulating shielding layer of the cable at one end to the direction of the stress control cone, covering the top of the stress control cone by no less than 10mm, and winding the semi-conductive rubber belt on the semi-conductive coating in a semi-lap joint manner to recover the insulating shielding layer of the insulating joint; at least one layer of copper net is wound on the semi-conductive rubber belt and is firmly fixed; push away insulating formula copper casing to insulation joint department, the insulating section of epoxy of insulating formula copper casing is placed in the insulating section department of insulation joint insulation shielding layer, adopts the lead sealing with the copper pipe and the cable metal sheath reliable connection of the insulating formula copper casing at both ends, evenly pours into insulating formula copper casing with high-pressure fire-retardant glue and seals the mouth of encapsulating, with thermal contraction pipe heating shrinkage to lead sealing position and cover cable outer protective layer and copper casing protective layer, form cable insulation joint's outer protective layer and resume.
Preferably, in step 5), the extruder is a miniature single screw extruder.
Preferably, in step 6), eddy current induction heating is adopted for heating the cable conductor at the joint.
Preferably, the extrusion glue injection mold comprises a first flow divider, a second flow divider, a first outer mold and a second outer mold; first shunt is for advancing gluey end, the second shunt is for advancing the opposite end of gluey end, first shunt and second shunt merge the back outer wall and form the reposition of redundant personnel structure, the reposition of redundant personnel structure with the inner wall cooperation of first external mold and second external mold forms the stream and glues the way, flow glue the way by the even play of annular is glued after the crowded notes shunt mould advances to glue, realizes right the even crowded notes of crowded notes make-up machine body mould die cavity.
The flow dividing structure comprises a first flow dividing structure positioned at the first flow divider and a second flow dividing structure positioned at the second flow divider; the first flow dividing structure is arranged to enable the first flow divider to be matched with the first outer die to form a first flow channel which divides the flow to two sides and a second flow channel which gradually and uniformly diffuses from two sides to the middle; the second flow dividing structure is arranged to enable the second flow divider and the second outer die to form a third flow channel with two sides gradually and uniformly diffusing towards the middle; the first flow channel, the second flow channel and the third flow channel are combined to form the rubber flow channel; and after the molten rubber material flows out of the first flow channel, the molten rubber material respectively flows to the second flow channel and the third flow channel, so that annular uniform rubber discharging is formed.
Preferably, the first flow channel is located at the lower end of the first flow divider, the first outer mold is provided with a glue inlet, and the glue inlet is communicated with the first flow channels on the two sides.
An insulating joint is manufactured by adopting the process.
The present invention includes but is not limited to the following benefits:
1) the manufacturing process is convenient to operate, the manufactured insulating joint and the cable body can form equivalent connection characteristics, and the mechanical and electrical properties of the cable body are met; the insulating layer has good cross-linking with the original cable and other recovery layers, so that a movable interface is avoided;
2) the insulating joint forming device is simple in structure, easy to assemble on site and convenient to operate by the joint process manufactured by the forming device;
3) the joint forming device has uniform glue discharging and good forming effect.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other solutions can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic view of the installation of the joint forming mold and the elastic rubber bushing of the present invention;
FIG. 2 is a schematic view of the joint forming mold of the present invention filled with glue;
FIG. 3 is a schematic view of the main structure of the insulated joint of the present invention;
FIG. 4 is a schematic view of the overall structure of the insulated joint of the present invention;
FIG. 5 is a graph of the potential and electric field distribution of the insulated joint made in accordance with the present invention;
FIG. 6 is a schematic structural view of a joint forming apparatus provided in the present invention;
FIG. 7 is a schematic view of a structure of a mold for injecting paste according to the present invention;
FIG. 8 is a front view of a first shunt provided by the present invention;
FIG. 9 is a front view of a second diverter provided by the present invention;
FIG. 10 is a schematic diagram of a combination structure of a first shunt and a second shunt provided in the present invention;
fig. 11 is a cross-sectional view of a joint forming apparatus provided by the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be taken as limiting the scope of the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
The technical solution of the present invention will be described in detail with reference to the accompanying drawings 1 to 11 in conjunction with the embodiment.
A manufacturing process of an insulating joint of a single-core cross-linked power cable of 500kV or below comprises the following steps:
1) selecting a semi-conductive shielding material to manufacture a partially-crosslinked horn-shaped geometric stress control cone 5 in a factory (the manufacturing is the prior art and is not described again), wherein the semi-conductive shielding material mainly comprises ethylene-vinyl acetate copolymer (EVA), conductive carbon black, an antioxidant and a crosslinking agent;
the geometric stress control cone (which can have different shapes and sizes and is designed according to actual requirements) is designed according to different voltage grades and different cable specifications, so that the distortion field intensity at the insulation shielding fracture of the cable is effectively controlled; the semi-conductive shielding material is made into a partially cross-linked geometric stress control cone in a factory, so that grafting, melting and combination with a joint insulating material at the later stage are facilitated, and the semi-conductive shielding material is well packaged in vacuum.
2) The crosslinkable polyethylene resin composition is selected as a main insulating material of the joint, and mainly comprises polyethylene resin, a chemical crosslinking agent, an antioxidant and a crosslinking promoter.
The partial cross-linking geometric stress control cone made of the cross-linkable polyethylene resin composition and the semi-conductive shielding material and the original insulating layer of the cable can be subjected to cross-linking grafting reaction under certain conditions without air gap fusion, so that the generation of partial discharge caused by the existence of an interface is avoided, and the electrical performance and the heat resistance can meet the requirements of a cable system.
3) Stripping a cable conductor 9, a conductor shielding layer 6, a cable insulating layer 4, an insulating shielding layer 1, a metal sheath 13 and an outer protection layer 12 according to the process size; respectively sleeving an insulating copper shell 22, a heat-shrinkable tube 15, a partially cross-linked geometric stress control cone 5 and an expanded rubber elastic sleeve 400 on a cable; integrally welding the cable conductors 9 at two ends by adopting a fusion welding mode to form a welding end 10, and processing the welding end to be consistent with the cable conductors 9 in size; adopting a semi-conductive belt or a semi-conductive pipe made of a semi-conductive shielding material to recover a conductor shielding layer 6, winding a layer of heat-resistant isolation film (preventing the semi-conductive material from being bonded on a heating mould), installing a semi-heating mould and heating, raising the temperature to a set crosslinking temperature, synchronously and gradually tightening the mould in the temperature raising process, carrying out heat preservation and pressure maintenance for a certain time, naturally cooling to the ambient temperature, then carrying out mould removal, and carrying out shape modification treatment on a recovered joint conductor shielding layer 8 until the joint conductor shielding layer is smooth and flat;
4) installing an extrusion injection glue mold 100 to one end of the joint, the extrusion injection glue mold 100 being used for providing a molten glue stock; contracting the rubber elastic sleeve 400 (playing a role in thermal buffering and providing internal pressure of the mold) to a joint position, wherein a rubber outlet of the extrusion rubber injection mold 100 is communicated with an inner side cavity of the rubber elastic sleeve 400; installing an extrusion molding machine body mold 200 to the periphery of the joint and fixedly connecting the extrusion molding machine body mold 200 with an extrusion glue injection mold 100, wherein the extrusion molding machine body mold 200 consists of two symmetrical machine body half molds and forms a joint mold cavity; pushing a part of the cross-linking geometric stress control cone 5 to one end matched with the rubber elastic sleeve 400, pushing a supporting heating insert mold 300 (the supporting part of the cross-linking geometric stress control cone 5 is not deformed after being heated, or heating can be carried out to ensure that the part of the cross-linking geometric stress control cone 5 is uniformly heated) into a socket of the part of the cross-linking geometric stress control cone 5, and then fixedly connecting the supporting heating insert mold 300 with the extrusion molding machine body mold 200; the supporting heating insert mold 300 is composed of two symmetrical supporting heating insert half molds, each supporting heating insert half mold comprises a supporting horn section 301 and a straight line section 302, and the supporting horn sections 301 and the straight line sections 302 are matched with the shapes of the partial cross-linking geometric stress control cones 5;
in this embodiment, the specific structure of the injection molding die 100 is not limited as long as the injection molding can be realized. Those skilled in the art will appreciate that this functionality can be achieved by a variety of conventional structures.
5) When the extrusion molding machine body mold 200, the supporting heating insert mold 300 and the extrusion injection molding mold 100 are heated to the extrusion temperature of 90-105 ℃ (the temperature is the cross-linking agent in the cross-linkable polyethylene resin composition for starting reaction and the colloid has good flowing performance), the preheated extruding machine is started, the cross-linkable polyethylene resin composition material forms flowable colloid through the extruding machine, and then is injected into the extrusion molding machine body mold 200 through the extrusion injection molding mold 100, when the colloid 7 is filled in the whole extrusion molding machine body mold 200 and flows out from a colloid discharge port, the colloid 7 fills the rubber elastic rubber hose 400, the rubber elastic hose 400 compresses the internal colloid 7 due to the elastic characteristic of the rubber elastic hose 400, and the colloid 7 has expansion characteristic under the action of the internal temperature of the extrusion molding machine body mold, so that the designed elastic rubber hose 400 can provide stable internal pressure, because the rubber has certain heat resistance, poor crosslinking caused by overheating of the joint due to direct heating of the colloid 7 by the mold 200 of the extrusion molding machine body can be avoided;
6) closing the extruding machine, heating the extrusion molding machine body mold 200 and the support heating insert mold 300, and simultaneously heating the cable conductor 9 at the joint (i.e. heating the inside and the outside simultaneously, wherein the heating of the cable conductor 9 can make the internal temperature more uniform without large temperature gradient deviation, solving the defect that the internal temperature is not uniform due to the heating of a single external mold), when the temperature of the (original) cable insulation layer 4 is increased to 160 ℃, and the surface temperature of the partial cross-linking geometric stress control cone 5 reaches 135-155 ℃ (the temperature at which the partial cross-linking geometric stress cone begins to be grafted and cross-linked with the cross-linkable polyethylene resin composition, and can realize the mutual melting and combination without air gap fusion), the colloid 7 (the cross-linkable polyethylene resin composition) is subjected to rapid graft cross-linking reaction under the conditions of the given temperature of 145-175 ℃, the pressure of 1.0-3.0PMa and the time of 2h-6h, after graft cross-linking reaction, the colloid 7 is grafted and fused with the (original) cable insulation layer 4, the partial cross-linking geometric stress control cone 5 and the recovered joint conductor shielding layer 8.
Preferably, the method further comprises a step 7) of removing all the dies and the rubber elastic sleeve 400 after naturally cooling to room temperature, polishing and shaping the insulating layer of the insulating joint until the surface is smooth and flat, and covering the insulating layer by 2-12mm through the stress control cone 5 to form the insulating section 11 of the insulating and shielding layer of the cable at two ends. The joint insulating layer has no defects such as air holes, impurities, unevenness and the like.
Preferably, the method further comprises a step 8) of uniformly coating the semi-conductive coating 3 on the colloid 7 in the direction from the fracture of the insulating shielding layer 1 of the cable at one end to the stress control cone 5 to cover the top of the stress control cone 5 by no less than 10mm, and winding the semi-conductive rubber belt 2 on the semi-conductive coating 3 in a half lap joint manner to recover the insulating shielding layer of the insulating joint; at least one layer of copper net 17 is wound on the semi-conductive rubber belt 2 and is firmly fixed; pushing an insulating copper shell 22 to an insulating joint, placing an epoxy insulating section 20 of the insulating copper shell 22 at an insulating section 11 of an insulating shielding layer of the insulating joint, reliably connecting copper pipes of the insulating copper shells at two ends with a cable metal sheath 13 by adopting a lead sealing 14, uniformly pouring high-pressure flame-retardant glue 21 into the insulating copper shell 22, sealing a glue pouring opening 19, heating and shrinking a heat shrinkable tube 15 to the position of the lead sealing 14, and covering a cable outer protective layer 12 and a copper shell protective layer 16 to form the outer protective layer recovery of the cable insulating joint; the inner core and the outer core of the coaxial cable are respectively connected with binding posts 18 at two ends of the insulating copper shell, and the reduction of the induced voltage of the cable circuit sheath can be completed by transposition through the cross interconnection box.
Fig. 5 is a distribution diagram of the potential and the electric field of the single-core crosslinked cable insulation joint manufactured by the process of the invention, and it can be seen that the potential and the electric field distribution inside the joint are relatively uniform, the electric field intensity at the position of the insulation section can meet the use requirements of the field, and the stress control cone can well solve the distortion field intensity at the insulation shielding fracture of the cable, and can completely achieve the electric performance of the cable body.
Preferably, in step 5), the extruder is a miniature single screw extruder.
Preferably, in step 6), eddy current induction heating is used for heating the cable conductor 9 at the joint.
Preferably, the injection molding die 100 comprises a first shunt 101, a second shunt 102, a first outer die 103 and a second outer die 104; first shunt 101 is for advancing gluey end, second shunt 102 is for advancing gluey opposite end of end, outer wall forms the reposition of redundant personnel structure after first shunt 101 and the merger of second shunt 102, the reposition of redundant personnel structure with the inner wall cooperation of first external mold 103 and second external mold 104 forms glue flowing channel 109, glue flowing channel 109 by after crowded notes shunt mould 100 advances gluey, form the even glue that goes out of annular, the realization is right the even crowded notes of crowded moulding machine body mould 200 die cavity.
The flow dividing structure comprises a first flow dividing structure 107 located at the first flow divider 101 and a second flow dividing structure 108 located at the second flow divider 102; the first flow dividing structure 107 is configured to enable the first flow divider 101 and the first outer mold 103 to cooperate to form a first flow channel 105 divided to two sides and a second flow channel 118 gradually and uniformly diffused from two sides to the middle; the second flow dividing structure 108 is arranged to enable the second flow divider 102 and the second outer die 104 to form a third flow channel 106, wherein the third flow channel is gradually and uniformly diffused from two sides to the middle; the first flow channel 105, the second flow channel 118 and the third flow channel 106 are combined to form the rubber channel 109; after flowing out of the first flow channel 105, the molten rubber material flows to the second flow channel 118 and the third flow channel 106 respectively, so as to form annular uniform rubber discharge. In order to form the first flow channel, the second flow channel, and the third flow channel, in this embodiment, the first flow divider is a peach-shaped flow divider, and the second flow divider is a mountain-shaped flow divider, but those skilled in the art may also set other shapes as long as the first flow channel that divides to both sides, the second flow channel that gradually and uniformly diffuses from both sides to the middle, and the third flow channel that gradually and uniformly diffuses from both sides to the middle can be realized.
Preferably, the first flow channel 105 is located at the lower end of the first flow divider 101, the first outer mold 103 is provided with a glue inlet 112 (communicated with the glue injection port), and the glue inlet 112 is communicated with the first flow channels 105 on the two sides.
Preferably, the first shunting structure 107 includes shunting protrusions, and the glue inlets 112 are respectively communicated to two sides of the shunting protrusions. Of course, those skilled in the art may also omit the flow dividing protrusion, the glue inlet 112 is directly communicated to the joint of the first flow channels 105 on both sides, and the molten glue material enters and then is divided to the first flow channels 105 on both sides.
Preferably, the bottom of the second shunt 102 and the bottom of the second outer die 104 are respectively provided with a first through hole 110 and a first threaded hole 111, and the first through hole and the first threaded hole are locked and matched by using a bolt or a screw; the first shunt 101 and the first outer die 103 are locked and matched in the same manner (i.e. the bottom of the first shunt is provided with a first through hole and a first threaded hole respectively).
Preferably, the second shunt 102 and the second outer mold 104 respectively include a first flange 115 and a second flange 116, and the first through hole 110 and the first threaded hole 111 are respectively disposed on the first flange 115 and the second flange 116; correspondingly, the first through hole and the first threaded hole on the first shunt 101 and the first outer die 103 are also respectively arranged on the flange thereon.
Preferably, the outer walls of the first outer mold 103 and the second outer mold 104 are respectively provided with at least one first connector 113, the first connector 113 is provided with a second through hole 114, and the first outer mold 103 and the second outer mold 104 are connected by bolts and nuts.
Preferably, four first connecting pieces 113 are respectively and rectangularly distributed on the outer walls of the first outer die 103 and the second outer die 104, and the first connecting pieces 113 are connected to the outer walls of the first outer die 103 and the second outer die 104 by welding.
Preferably, the extrusion injection molding machine body mold 100 and the extrusion injection molding machine body mold 200 are connected through a clamping groove, and the support heating insert mold 300 is mounted at the tail end of the extrusion injection molding machine body mold 200 through a bolt or screw connection.
Preferably, tail fixing threaded holes are uniformly distributed on the circumference of the tail end of the extrusion molding machine body mold 200; a first annular groove 202 is formed in the inner wall of the head end of the extrusion molding machine body mold 200, and correspondingly, a first annular protrusion 201 is formed at the front end of the first annular groove 202; the periphery of the glue outlet end of the glue injection mould 100 is provided with a second annular groove 117, and the first annular bulge 201 is inserted into the second annular groove 117 to form the clamping groove connection.
Preferably, the outer wall of the body half mold is provided with at least one second connector 203, the second connector 203 is provided with a third through hole 204, and the two body half molds are locked by bolts and nuts.
Preferably, four second connecting pieces 203 are respectively and rectangularly distributed on the outer walls of the two half-moulds of the machine body, and the second connecting pieces 203 are connected to the outer walls of the two half-moulds of the machine body by welding.
Preferably, fourth through holes 303 are uniformly distributed on the circumference of the supporting heating insert mold 300, and bolts or screws are used to penetrate through the fourth through holes 303 to be matched with tail fixing threaded holes of the machine body half mold, so as to fix the supporting heating insert mold 300 on the extrusion molding machine body mold 200.
An insulating joint is manufactured by adopting the process.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. A manufacturing process of an insulating joint of a single-core cross-linked power cable of 500kV or below is characterized by comprising the following steps:
1) selecting a semi-conductive shielding material to manufacture a partially-crosslinked horn-shaped geometric stress control cone in a factory;
2) selecting a crosslinkable polyethylene resin composition as a main insulating material of the joint;
3) stripping a cable conductor, a conductor shielding layer, a cable insulating layer, an insulating shielding layer, a metal sheath and an outer protective layer according to the process size; respectively sleeving an insulating copper shell, a heat-shrinkable tube, a partially cross-linked geometric stress control cone and an expanded rubber elastic sleeve on a cable; integrally welding the cable conductors at two ends by adopting a fusion welding mode to form a welding end, and processing the welding end until the size of the welding end is consistent with that of the cable conductor; adopting a semi-conductive belt or a semi-conductive pipe made of a semi-conductive shielding material to recover a conductor shielding layer, winding a layer of heat-resistant isolation film, installing a semi-heated mold and heating, raising the temperature to a set crosslinking temperature, synchronously and gradually tightening the mold in the temperature raising process, carrying out heat preservation and pressure maintaining for a certain time, naturally cooling to the ambient temperature, then carrying out mold removal, and carrying out shape modification treatment on the recovered joint conductor shielding layer until the joint conductor shielding layer is smooth and flat;
4) installing an extrusion glue injection mould to one end of the joint, wherein the extrusion glue injection mould is used for providing molten glue; contracting the rubber elastic sleeve to a joint position, wherein a rubber outlet of the extrusion rubber inlet mould is communicated with an inner side cavity of the rubber elastic sleeve; installing an extrusion molding machine body mold to the periphery of the joint and fixedly connecting the extrusion molding machine body mold with an extrusion glue injection mold, wherein the extrusion molding machine body mold consists of two symmetrical machine body half molds and forms a joint mold cavity; pushing the partially cross-linked geometric stress control cone to one end matched with the rubber elastic sleeve, pushing the support heating insert mold into a partially cross-linked geometric stress control cone socket groove, and then fixedly connecting the support heating insert mold with an extrusion molding machine body mold; the supporting heating insert mold consists of two symmetrical supporting heating insert half molds, each supporting heating insert half mold comprises a supporting horn section and a straight line section, and the supporting horn sections and the straight line sections are matched with the shapes of the partial cross-linking geometric stress control cones;
5) heating the extrusion molding machine body mold, the support heating insert mold and the extrusion glue injection mold to an extrusion temperature of 90-105 ℃, starting the preheated extruding machine, the crosslinkable polyethylene resin composite material forms flowable colloid after passing through an extruding machine, and then is injected into an extrusion molding machine body mould through an extrusion glue injection mould, when the colloid is filled in the whole die of the extrusion molding machine body and flows out from the colloid discharging port, the colloid fills up the rubber elastic rubber tube, because the elastic property of the rubber elastic sleeve compresses the internal colloid and the colloid has the expansion property under the action of the internal temperature of the extrusion molding machine body mold, the designed elastic rubber sleeve can provide stable internal pressure, because the rubber has certain heat resistance, the poor crosslinking caused by the overheating of the joint due to the direct heating of the colloid by the mold of the extrusion molding machine body can be avoided;
6) closing the extruding machine, heating the extrusion molding machine body mold and the support heating insert mold, heating the cable conductor at the joint, performing rapid grafting and crosslinking reaction on the colloid under the conditions of a given temperature of 145-.
2. The process of claim 1, wherein the semiconductive shield consists essentially of ethylene vinyl acetate, conductive carbon black, an antioxidant, and a crosslinking agent.
3. The process of claim 1, wherein the crosslinkable polyethylene resin composition consists essentially of a polyethylene resin, a chemical crosslinking agent, an antioxidant, and a crosslinking promoter.
4. The manufacturing process of claim 1, further comprising a step 7) of removing all the molds and the rubber elastic sleeves after naturally cooling to room temperature, polishing and shaping the insulating layer of the insulating joint until the surface is smooth and flat, and covering the insulating layer with a stress control cone by 2-12mm to form an insulating section of the insulating shielding layer of the cable at two ends.
5. The manufacturing process according to claim 4, further comprising step 8) of uniformly coating a semi-conductive coating on the colloid from the fracture of the insulation shielding layer of the cable at one end in the direction of the stress control cone to cover the top of the stress control cone by no less than 10mm, and winding the semi-conductive coating on the semi-conductive coating by using a semi-lap joint of a semi-conductive rubber tape to recover the insulation shielding layer of the insulation joint; at least one layer of copper net is wound on the semi-conductive rubber belt and is firmly fixed; push away insulating formula copper casing to insulation joint department, the insulating section of epoxy of insulating formula copper casing is placed in the insulating section department of insulation joint insulation shielding layer, adopts the lead sealing with the copper pipe and the cable metal sheath reliable connection of the insulating formula copper casing at both ends, evenly pours into insulating formula copper casing with high-pressure fire-retardant glue and seals the mouth of encapsulating, with thermal contraction pipe heating shrinkage to lead sealing position and cover cable outer protective layer and copper casing protective layer, form cable insulation joint's outer protective layer and resume.
6. The process of claim 1, wherein in step 5), the extruder is a miniature single screw extruder.
7. The process of claim 1, wherein in step 6) the cable conductor is heated at the joint by eddy current induction heating.
8. The manufacturing process of claim 1, wherein the extrusion glue injection mold comprises a first flow divider, a second flow divider, a first outer mold and a second outer mold; the first flow divider is a glue inlet end, the second flow divider is an opposite end of the glue inlet end, the outer wall of the combined first flow divider and second flow divider forms a flow dividing structure, the flow dividing structure is matched with the inner walls of the first outer mold and the second outer mold to form a glue flowing channel, and the glue flowing channel forms annular uniform glue outlet after glue is fed by the extrusion flow divider mold, so that uniform extrusion of the mold cavity of the extrusion molding machine body mold is realized;
the flow dividing structure comprises a first flow dividing structure positioned at the first flow divider and a second flow dividing structure positioned at the second flow divider; the first flow dividing structure is arranged to enable the first flow divider to be matched with the first outer die to form a first flow channel which divides the flow to two sides and a second flow channel which gradually and uniformly diffuses from two sides to the middle; the second flow dividing structure is arranged to enable the second flow divider and the second outer die to form a third flow channel with two sides gradually and uniformly diffusing towards the middle; the first flow channel, the second flow channel and the third flow channel are combined to form the rubber flow channel; and after the molten rubber material flows out of the first flow channel, the molten rubber material respectively flows to the second flow channel and the third flow channel, so that annular uniform rubber discharging is formed.
9. The manufacturing process of claim 8, wherein the first flow channel is located at the lower end of the first flow divider, the first outer die is provided with a glue inlet, and the glue inlet is communicated with the first flow channels on the two sides.
10. An insulated joint, characterized in that it is manufactured by the manufacturing process according to any of claims 1-9.
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