CN113021826A

CN113021826A - Production method of self-extinguishing electric cable

Info

Publication number: CN113021826A
Application number: CN202110220123.6A
Authority: CN
Inventors: 李淋舟
Original assignee: Chongqing Pigeon Electric Wire and Cable Co Ltd
Current assignee: Chongqing Pigeon Electric Wire and Cable Co Ltd
Priority date: 2021-02-26
Filing date: 2021-02-26
Publication date: 2021-06-25
Anticipated expiration: 2041-02-26
Also published as: CN113021826B

Abstract

The invention discloses a production method of a self-extinguishing thermal cable in the field of cable production, which comprises the following steps: A. extruding the insulating layer on the surface of the cable core by using an extruder to form a semi-finished cable; B. preparing a forming die; C. forming die is used at cable semi-manufactured goods outer shaping from sheath layer of putting out a fire outside on the extruder, including the second air cavity that is annular evenly distributed, there is the semiellipse shape gasbag strip that is annular evenly distributed in the second air cavity outside, all be equipped with first air cavity in the gasbag strip, first air cavity cross-sectional profile semicircular in shape, form first breakthrough point between first air cavity top and the gasbag strip top, form the second breakthrough point between adjacent gasbag strip transition department and the second air cavity, first air cavity and second air cavity are intracavity all filled with inert gas, inert gas's density in the first air cavity is greater than the inert gas's in the second air cavity density. The invention can produce the cable with the self-extinguishing function, and solves the problems that the cable in the prior art can not automatically prevent fire and retard flame, and can not effectively control the fire in time.

Description

Production method of self-extinguishing electric cable

Technical Field

The invention relates to the field of cable production, in particular to a production method of a self-extinguishing thermal cable.

Background

The wire and the cable are one of important materials for the infrastructure of the modern society, are used for providing energy or transmitting information for daily life, industrial production, information transmission and the like of people, and are an indispensable part of infrastructure for the development of the modern society. The main structure of the cable is a wire wrapped by a sheath material and an insulating material, the wire is mainly a metal wire, certain heat can be generated due to the existence of resistance in the process of transferring electric energy, particularly, a large amount of heat can be generated in the using process of a part of electric wires and cables with large transmission current and high voltage, and the spontaneous combustion phenomenon caused by overheating exists in the long-time using process. In addition, the electric wire and the cable have more combustion caused by the influence of the external environment in the use process. The fire can cause the sheath layer of the electric wire and cable to lose efficacy and then destroy the internal insulation and conductor to cause damage and other problems, and the fire seriously causes the fire to endanger the personal and property safety, so the fire resistance of the electric wire and cable is particularly important. The insulation and sheath materials are improved in the prior art, the flame-retardant material is researched and developed to be added into the insulation layer and the sheath layer as one of the components, but the common electric wire and cable has a multilayer structure, and the flame-retardant material is not added into each layer, so that spontaneous combustion caused by self overheating of the cable can be avoided to a certain extent, but the spontaneous combustion cannot be completely avoided, and partial sheath material can still be ignited due to overheating, and then an external object is ignited to cause a fire disaster. To sum up, the fire-proof and fire-retardant properties of the existing electric wire and cable still have defects, so that the electric wire and cable cannot be effectively and reliably prevented from burning, and the fire can not be effectively and timely prevented from being enlarged.

Disclosure of Invention

The invention aims to provide a production method of a self-extinguishing electric cable, which is used for producing the electric cable with the self-extinguishing function and solving the problems that the electric cable in the prior art cannot automatically prevent fire and retard flame and cannot effectively control the fire in time.

In order to achieve the purpose, the basic technical scheme of the invention is as follows: a production method of a self-extinguishing electric cable comprises the following steps:

A. extruding the insulating layer on the surface of the cable core by using an extruder to form a semi-finished cable;

B. preparing a forming die;

C. forming from the restrictive coating that puts out a fire with forming die outside cable semi-manufactured goods on the extruder, from the restrictive coating that puts out a fire including the second air cavity that is annular evenly distributed, there are a plurality of gasbag strips that are annular evenly distributed in the second air cavity outside, all be equipped with first air cavity in every gasbag strip, gasbag strip cross-section profile is semiellipse shape, first air cavity cross-section profile semicircular in shape, form first point of penetrating between first air cavity top and the gasbag strip top, it pierces through the point to form the second between adjacent gasbag strip transition department and the second air cavity, first air cavity and second air cavity are intracavity all filled with inert gas, inert gas's density is greater than the density of inert gas in the second air cavity in the first air cavity.

The principle and the advantages of the scheme are as follows: in practical application, a cable semi-finished product with an insulating layer is formed first, and then a self-extinguishing sheath layer with a special structure is extruded and formed on the cable semi-finished product by using a special forming die. The self-extinguishing sheath layer produced by the mould structure has a double-layer air cavity structure, can respectively contain inert gases and has thin-wall penetrating points. If the self-extinguishing cable produced like this meets external fire in the use, first penetrating point is located the outside and is influenced by the fire and inside atmospheric pressure influences and breaks at first for the inside inert gas of first air cavity releases in the second air cavity earlier, and the inert gas suppression of the inert gas of first air cavity release with the second air cavity release is on the cable surface, and oxygen near isolated cable, and then realize the fire prevention fire-retardant of self-extinguishing of cable.

And C, further, the forming die prepared in the step B comprises a cylindrical outer die and a cylindrical core die, the outer die is divided into a forming section and a connecting section along the axis direction, the outer die comprises a second core die, a first core die and a die holder which are connected in an embedded mode from inside to outside, the inner side wall of the forming section of the die holder is processed into a plurality of continuous forming grooves which are uniformly distributed in an annular mode, the forming section of the first core die is processed into a plurality of forming columns which are uniformly distributed in an annular mode, the forming section of the second core die is processed into an annular forming plate, each forming column is correspondingly located in one forming groove, the die holder is provided with a material injection hole communicated to the forming grooves, the middle of the connecting section of the second core die is provided with a material feeding hole, and the core die. The core mold is used as a guide structure of the cable semi-finished product to guide the cable semi-finished product to be conveyed along the central axis of the outer mold. The outer die is used as a sheath layer forming die, the inner side space surrounded by the forming plates on the second die core is used as an extrusion forming space of the solid sheath layer tightly attached to the cable insulating layer, and the outer wall of the forming plate, the surface of the forming column and the inner wall of the die holder are surrounded to form an extrusion forming space of the hollow sheath layer surrounding the solid sheath layer. The sheath material gets into from annotating material hole and feed port in the extrusion molding process, and the shaping post forms a plurality of first air cavities of surrounding the distribution of cable semi-manufactured goods in the hollow sheath layer inside during extrusion molding, forms the first penetrating point of thin-walled structure between the tank bottom in shaping post and shaping groove. The forming plate forms a second air cavity surrounding the semi-finished cable between the hollow sheath layer and the solid sheath layer, and a second penetrating point of a thin-wall structure is formed between the part between the adjacent forming grooves and the forming plate.

And further, processing the forming groove into a semi-elliptical groove in the step B, processing the forming column into a semi-cylinder, positioning the center of the cross section of the forming column on the short shaft of the cross section profile of the forming groove, and filling the sheath material between the forming column and the forming groove with an extrusion forming air bag strip in the step C. The thickness of the jacket material outside the first air cavity is gradually thickened from the middle to the two sides as the optimization, the structure strength is enough, the inert gas in the first air cavity can be stably and effectively restrained, the prepressing force from the two sides to the middle is provided, the penetrating point of the first air cavity is guaranteed to be preferentially broken when the first air cavity takes effect, the inert gases with different densities can be further combined to be used, the inert gas in the first air cavity can be pressed on the surface of the cable, the more stable and effective fire extinguishing and flame retardant effects are further obtained, the appearance contour of the self-extinguishing cable produced in the mode is provided with a plurality of arc-shaped surfaces, and the external force impact resistance is better.

Furthermore, in the step B, the material injection hole is communicated to the end part of the short shaft of the cross section outline of the forming groove, and in the step C, the sheath material enters the forming groove from the material injection hole to form a first penetrating point. The sheath material can be directly injected to the first air cavity penetrating point preferably, so that the sheath material is ensured to be preferentially filled and molded at the first air cavity penetrating point with a narrow molding space, and the defect that the sheath material at the first air cavity penetrating point is not filled completely is effectively avoided.

And further, in the step B, an inflation channel is arranged in the forming column and the forming plate, inflation holes are formed in the end parts of the forming column and the forming plate, and in the step C, inert gas enters the first air cavity and the second air cavity from the inflation holes. The flowing air flow is preferably formed in the forming column and the forming plate, the inert gas can be directly filled in the forming column and the forming plate, so that the forming column and the forming plate can be cooled and shaped to a certain degree through the flowing air flow while forming the first air cavity and the second air cavity, the inert gas is injected in real time, the formed self-extinguishing cable is directly produced, and the production is more efficient.

Furthermore, in the step B, a plurality of notches are formed in the forming plate, and each notch faces one forming column correspondingly. As preferablely like this through the setting of incision in the crowded fashioned in-process solid restrictive coating of sheath material and cavity restrictive coating be connected and form wholly, the shaping back second air cavity has a plurality ofly and encircles in the semi-manufactured goods cable outside, the support on solid restrictive coating can be obtained to the cavity restrictive coating, guarantees in the use that the cable core circumference of cable can both obtain gaseous fire prevention fire-retardant protection to the incision makes the second air cavity pierce through the point and keeps effective effect thickness towards the shaping post.

Further, in the step C, the sheath material is heated to over 180 ℃, and the heated sheath material is injected into the outer die from the material injection hole and the material feeding hole simultaneously under the pressure of 0.8-1.5 MPa. The temperature is preferably adopted to ensure the thermoplasticity of the sheath material, the pressure in a specific range is matched to ensure that the sheath material can be effectively coated on a cable semi-finished product after being injected from the feed port, and the sheath material enters from the material injection hole to completely fill the gaps among the forming columns, the forming grooves and the forming plates, so that the first air cavity and the second air cavity are ensured to be complete in structure, good sealing performance is achieved, and the leakage of filled inert gas is effectively avoided.

Further, the cable semi-finished product is arranged in the core mould in a penetrating mode in the step C, the end portion of the cable semi-finished product is kneaded and sealed after the sheath material is extruded, and then the cable semi-finished product and the end portion of the cable semi-finished product are pulled at the speed of 10-30 m/min. The end parts of the first air cavity and the second air cavity are preferably sealed through kneading, so that the subsequent inflation stability is ensured, and sufficient shaping time is provided by controlling the drawing speed, so that the stability in molding of the first air cavity and the second air cavity is further ensured.

And C, filling carbon dioxide gas into the inflation channel of the forming column, filling nitrogen gas into the inflation channel of the forming plate, wherein the filling pressure of the carbon dioxide gas and the nitrogen gas is 0.15-0.2 MPa. The optimal inert gas is relatively low in acquisition cost, the limitation on inflation pressure ensures that the first air cavity and the second air cavity have pre-pressure, the regularity of the appearance can be ensured, and the inert gas can be timely released to extinguish fire and retard fire when the inert gas meets a fire condition through the matching of internal air pressure and external fire condition.

And further, in the step C, the cable formed with the self-extinguishing sheath layer is cooled by air and then water, wherein the air cooling temperature is 20-25 ℃, the time is 5-10S, and the water cooling is carried out by adopting a room temperature water tank to cool to room temperature. As preferring like this earlier through the air-cooled precooling of stereotyping of restrictive coating of extruding of short time, guarantee restrictive coating shape stable in structure, first air cavity, second air cavity receive the extrusion to glue glutinous in avoiding transportation process, and then carry out ultimate cooling through the water-cooling and stereotype for regular, the inside inert gas of the self-extinguishing power cable appearance of production effectively fills, possesses reliable effectual fire-retardant property from extinguishing.

Drawings

FIG. 1 is an isometric view of a forming die in an embodiment of the invention;

FIG. 2 is a front view of a forming die in an embodiment of the present invention;

FIG. 3 is a side view of a forming die in an embodiment of the present invention;

FIG. 4 is a sectional view taken along line A-A of FIG. 3;

fig. 5 is a cross-sectional view of a self-extinguishing cable in an embodiment of the present invention.

Detailed Description

The following is further detailed by way of specific embodiments:

reference numerals in the drawings of the specification include: the die holder comprises a die holder 1, a forming column 2, a forming plate 3, a forming groove 4, a material injection hole 5, an inflation hole 6, a mountain-shaped bulge 7, a notch 8, a core die 9, a first die core 10, a second die core 11, a feeding hole 12, a cable core 13, an insulating layer 14, a solid sheath layer 15, a first air cavity 16, a second air cavity 17, a first penetration point 18 and a second penetration point 19.

The embodiment provides a production method of a self-extinguishing electric cable, which comprises the following steps:

B. preparing a forming die, as shown in fig. 1 and fig. 2, comprising a cylindrical outer die and a cylindrical core die 9, wherein the outer die is divided into a forming section and a connecting section along the axial direction, the outer die comprises a second core die 11, a first core die 10 and a die holder 1 which are connected in an embedded manner from inside to outside, the inner side wall of the forming section of the die holder 1 is processed into eight continuous forming grooves 4 which are uniformly distributed in a ring shape, the forming grooves 4 are processed into semielliptical grooves, the forming section of the first core die 10 is processed into eight forming columns 2 which are uniformly distributed in a ring shape, each forming column 2 is correspondingly positioned in one forming groove 4, the forming columns 2 are processed into semicylinders, the centers of the cross sections of the forming columns 2 are positioned on the short axes of the cross section outline of the forming grooves 4, the forming section of the second core die 11 is processed into an annular forming plate 3, eight notches 8 are arranged on the forming plate 3, each notch 8 correspondingly faces, a material injection hole 5 communicated to a forming groove 4 is formed in a die holder 1, as shown in a combined drawing of fig. 3 and 4, a short shaft end part communicated to the cross section outline of the forming groove 4 is formed in the material injection hole 5, a feeding hole 12 is formed in the middle of a connecting section of a second die core 11, a core die 9 is arranged in the feeding hole 12 in a penetrating mode, inflation channels are arranged inside a forming column 2 and a forming plate 3, and inflation holes 6 are formed in the end parts of the forming column 2 and the forming plate 3;

C. the semi-finished product of the cable is arranged in a core mould 9 in a penetrating way on an extruder, a self-extinguishing sheath layer is formed outside the semi-finished product of the cable by a forming mould, the sheath material is heated to the temperature above, the heated sheath material is injected into an outer mould from a material injection hole 5 and a material inlet hole 12 at the same time under the pressure of 0.8-1.5MPa, the end part of the extruded sheath material is kneaded and sealed and then is drawn together with the semi-finished product of the cable at the speed of 10-30 m/min; filling carbon dioxide gas into the inflation channel of the forming column 2, and filling nitrogen gas into the inflation channel of the forming plate 3, wherein the filling pressure of the carbon dioxide gas and the nitrogen gas is 0.15-0.2 MPa; cooling the cable with the self-extinguishing sheath layer by air at 20-25 ℃ for 5-10S, and cooling to room temperature by using a room temperature water tank; as shown in fig. 5, the self-extinguishing sheath layer comprises eight second air cavities 17 which are uniformly distributed in an annular shape, eight air bag strips which are uniformly distributed in an annular shape are arranged outside the second air cavities 17, a first air cavity 16 is arranged in each air bag strip, the cross section profile of each air bag strip is semi-elliptical, the cross section profile of each first air cavity 16 is semi-circular, a first penetrating point 18 is formed between the top of each first air cavity 16 and the top of each air bag strip, a second penetrating point 19 is formed between the transition position of each adjacent air bag strip and the corresponding second air cavity 17, inert gases are filled in each first air cavity 16 and the corresponding second air cavity 17, and the density of the inert gases in each first air cavity 16 is greater than that of the inert gases in the corresponding second air cavities.

Before use, the first mold core 10 is nested and inserted in the mold base 1 through a stepped structure, the molding columns 2 are inserted into the molding grooves 4 in a one-to-one correspondence mode, the second mold core 11 is inserted in the inner side of the first mold core 10 through the stepped structure to form an outer mold, the core mold 9 is assembled on an extruder for cable production, the outer mold is concentrically assembled on the outer side of the core mold 9, and the core mold 9 is inserted into the outer mold. In the production process, the cable core 13 is firstly extruded with the insulating layer 14 to form a semi-finished cable product, then the semi-finished cable product is sent into the core mould 9, and the sheath material is added to start the extruder. The sheath material enters the molding cavity on the inner side of the outer mold from the material injection hole 5 and the material feeding hole 12, enters the inner side of the second mold core 11 from the material feeding hole 12 and is coated on the surface of the semi-finished product of the cable in the middle to form a solid sheath layer 15, further enters the gap between the molding plate 3 and the molding column 2 from the notch 8 on the molding plate 3 and is filled in a spreading way towards two sides; the sheath material enters an air cavity between the die holder 1 and the first die core 10 from the material injection hole 5 and is filled from the arc vertex of the forming column 2 to the two sides in a spreading way, so that the sheath material can effectively fill the forming cavity formed by the outer die and the core die 9. In the extrusion process of the sheath material, the forming column 2 forms a first air cavity 16 in the formed sheath, the forming plate 3 forms a second air cavity 17 in the formed sheath, carbon dioxide and nitrogen are continuously input into the forming column 2 and the forming plate 3, the carbon dioxide is injected into the first air cavity 16 from the inflating hole 6, and the nitrogen is injected into the second air cavity 17 from the inflating hole 6. As shown in the figure, the formed self-extinguishing cable is coated with a solid sheath layer 15 outside an insulating layer 14, the outer side of the solid sheath layer 15 is provided with a layer of annular second air cavity 17 filled with nitrogen, the outer side of the second air cavity 17 is provided with a layer of annular first air cavity 16 filled with carbon dioxide, the second air cavity 17 is fan-shaped, and the first air cavity 16 is semicircular. The wall thickness of first air chamber 16 increases from the middle, which is first penetration point 18, to both sides, and first penetration point 18 has a thickness of 0.8mm, so that the carbon dioxide gas inside is squeezed from both sides to the middle. The mountain-shaped protrusion 7 between two adjacent molding grooves 4 forms a sharp groove on the sheath layer as a second penetrating point 19, and the thickness of the second penetrating point 19 is 1 mm. When meetting the condition of a fire in the cable use, first penetrating point 18 is influenced by the condition of a fire earlier and is broken, releases carbon dioxide gas and covers on the cable surface, and second penetrating point 19 releases nitrogen gas after breaking, and nitrogen gas density is less than the carbon dioxide, and then nitrogen gas is suppressed on the cable surface by carbon dioxide, and is isolated with the near air of cable surface for the cable loses the essential oxygen of burning, makes the cable can not be ignited, realizes the fire prevention fire-retardant of self-extinguishing of cable.

The foregoing is merely an example of the present invention and common general knowledge in the art of specific structures and/or features of the invention has not been set forth herein in any way. It should be noted that, for those skilled in the art, without departing from the structure of the present invention, several changes and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.

Claims

1. A production method of a self-extinguishing electric cable is characterized by comprising the following steps: the method comprises the following steps:

B. preparing a forming die;

2. A method of producing a self-extinguishing electric cable according to claim 1, characterized in that: the forming die prepared in the step B comprises a cylindrical outer die and a cylindrical core die, the outer die is divided into a forming section and a connecting section along the axis direction, the outer die comprises a second core die, a first core die and a die holder which are connected in an embedded mode from inside to outside, the inner side wall of the forming section of the die holder is processed into a plurality of continuous forming grooves which are uniformly distributed in an annular mode, the forming section of the first core die is processed into a plurality of forming columns which are uniformly distributed in an annular mode, the forming section of the second core die is processed into an annular forming plate, each forming column is correspondingly located in one forming groove, material injection holes communicated with the forming grooves are formed in the die holder, a feeding hole is formed in the middle of the connecting section of the second core die, and the core die penetrates through the feeding hole.

3. A method of producing a self-extinguishing electric cable according to claim 2, characterized in that: and in the step B, the forming groove is processed into a semi-elliptical groove, the forming column is processed into a semi-cylinder, the circle center of the section of the forming column is positioned on the short shaft of the section outline of the forming groove, and in the step C, the sheath material is filled between the forming column and the forming groove to form the extrusion-molded air bag strip.

4. A method of producing a self-extinguishing electric cable according to claim 3, characterized in that: and in the step B, the material injection hole is formed and communicated to the end part of the short shaft of the cross section profile of the forming groove, and in the step C, the sheath material enters the forming groove from the material injection hole to form a first penetrating point.

5. A method of producing a self-extinguishing cable according to claim 4, characterized in that: and in the step B, an inflation channel is arranged in the forming column and the forming plate, inflation holes are formed in the end parts of the forming column and the forming plate, and inert gas enters the first air cavity and the second air cavity from the inflation holes.

6. A method of producing a self-extinguishing cable according to claim 5, characterized in that: and in the step B, a plurality of notches are formed in the forming plate, and each notch correspondingly faces one forming column.

7. A method of producing a self-extinguishing electric cable according to claim 6, characterized in that: and C, heating the sheath material to be above 165-175 ℃, and injecting the heated sheath material into the outer die from the material injection hole and the material feeding hole simultaneously.

8. A method of producing a self-extinguishing electric cable according to claim 7, characterized in that: and C, penetrating the cable semi-finished product into a core mold, kneading and sealing the end part after the sheath material is extruded, and drawing and demolding the cable semi-finished product together.

9. A method of producing a self-extinguishing electric cable according to claim 8, characterized in that: and C, filling carbon dioxide gas into the inflation channel of the forming column, filling nitrogen gas into the inflation channel of the forming plate, wherein the filling pressure of the carbon dioxide gas and the nitrogen gas is 0.15-0.2 MPa.

10. A method of producing a self-extinguishing electric cable according to claim 9, characterized in that: and C, firstly cooling the cable with the self-extinguishing sheath layer by air at 20-25 ℃ for 5-10 seconds, and then cooling the cable to room temperature by using a room temperature water tank.