A cable capable of delayed explosion and combustion in the event of overload and short circuit and its production method

Abstract

The invention discloses a cable capable of delayed explosion and combustion in the event of an overload and short circuit, and a production method thereof, relating to the technical field of cables. The cable uses annealed soft copper wire as a conductor, a halogen-free, low-smoke, flame-retardant cross-linked polyolefin as an insulation layer, and a nylon cable material as a protective layer; wherein the nylon cable material is composed of a mass ratio of PA11:90%, PA66:9%, an antioxidant:0.5%, and an anti-hydrolysis agent:0.5%; the insulation layer and the protective layer form a double-layer co-extruded covering layer wrapped around the conductor; the invention uses the combination of the halogen-free, low-smoke, flame-retardant cross-linked polyolefin of the insulation layer and the nylon cable material of the protective layer, so that after the conductor is overloaded and short-circuited to cause high temperature, the cable is delayed in explosion, and the time for external oxygen to contact the insulation layer is prolonged, thereby achieving the effect of delayed combustion; the problem that the existing explosion-delayed flame-retardant cables do not have the performance of delayed explosion and delayed combustion for a long time in the event of an overload and short circuit is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, in particular to a cable capable of delayed explosion and combustion in the event of overload and short circuit. Background Art

[0002] With the rapid development of industrialization and urbanization, the electrification of various buildings and facilities continues to increase. However, cables, as core components of power transmission, face complex environments and potential hazards during use, such as high temperatures, mechanical shock, chemical corrosion, and fire. In particular, in summer or under extreme operating conditions, short-term excessive currents can cause localized high temperatures in cables, leading to bursts and combustion. In these situations, the performance of traditional cables may not be sufficient to cope with these harsh conditions, making it difficult to effectively ensure the safe operation of facilities and personal safety.

[0003] In fire incidents, cables are often a major source of ignition or a factor in the spread of fire. For example, when cables burn, they release high-temperature flames, toxic smoke, and corrosive gases, which not only endanger lives but can also damage secondary equipment. Furthermore, in flammable and explosive environments, such as petrochemical plants and mining, sparks or high temperatures generated by cables can directly trigger explosions. Therefore, the development of cables with both delayed burst and delayed combustion features is essential.

[0004] At present, through the optimization of new materials and structures, the performance of delayed burst and delayed combustion cables has been improved, which is specifically reflected in the following aspects:

[0005] (1) Flame retardant technology: The application of flame retardants effectively reduces the possibility of cables spreading flames in fire.

[0006] (2) Fire-resistant technology: Use high-temperature resistant materials (such as mica tape) to ensure that the cable maintains electrical function at high temperatures.

[0007] (3) Anti-mechanical shock technology: Metal armor and high-strength outer sheath are used to enhance the cable's shock resistance and avoid the risk of explosion.

[0008] (4) Environmental protection and low toxicity: Low smoke zero halogen (LSZH) technology reduces the release of toxic gases in fires and increases the probability of survival of personnel.

[0009] There are many types of delayed burst and delayed combustion cables, including:

[0010] Flame-retardant cables effectively slow the spread of flames by adding flame retardants (such as aluminum hydroxide and magnesium hydroxide) to the outer sheath or insulation layer. Flame-retardant cables are divided into single flame-retardant and low-smoke halogen-free flame-retardant types. Low-smoke halogen-free materials are more environmentally friendly and reduce toxicity and corrosiveness during combustion.

[0011] The delayed burst characteristic of explosion-retardant cables is achieved through a multi-layer structure, including metal armor, pressure-resistant sheath, and tensile core wire. This design effectively withstands mechanical shock, high voltage, and environmental stress, ensuring that the cable does not break or leak external sparks.

[0012] Although today's cables are relatively mature in terms of delayed burst, flame retardancy and insulation, there are still technical challenges. Delayed burst and delayed combustion cables are core components of modern industrial and urban facilities. Today's high-voltage and low-voltage power rooms are equipped with intelligent monitoring. Therefore, if electronic components have a delay function under extreme working conditions, they will not burn immediately due to high temperature when overload and short circuit occur. Instead, they will delay bursting and burning within a certain delay time, so that intelligent monitoring can have enough time to warn when uncontrollable failures occur in electronic components. Among them, if the cable can achieve delay and have both delayed burst and delayed combustion performance, keep up with the current technological development of safety electrical components, and use this technology, it will further improve the comprehensive performance of delayed burst and delayed combustion cables, and provide a more solid guarantee for the safety of electricity use in life and industry.

[0013] In summary, it is found that the existing technology has at least the following technical problems:

[0014] The existing explosion-delayed flame-retardant cables do not have the problem of long-term delayed explosion and delayed combustion performance under overload and short-circuit conditions. Summary of the Invention

[0015] The purpose of the present invention is to provide a cable that can delay explosion and combustion under overload and short circuit conditions, so as to solve the problem that existing explosion-delayed flame-retardant cables do not have the performance of delayed explosion and delayed combustion for a long time under overload and short circuit conditions.

[0016] The various technical effects that can be produced by the preferred technical solutions among the various technical solutions provided by the present invention are described in detail below.

[0017] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0018] The present invention provides a cable that can delay explosion and combustion in the event of an overload and short circuit. The cable comprises an annealed soft copper wire as a conductor, an insulating layer comprising a halogen-free, low-smoke, flame-retardant cross-linked polyolefin, and a protective layer comprising a nylon cable material. The nylon cable material is composed of a mass ratio of PA11: 90%, PA66: 9%, an antioxidant: 0.5%, and an anti-hydrolysis agent: 0.5%. The insulating layer and the protective layer form a double-layer co-extruded covering layer that is wrapped around the conductor. Through the combination of the halogen-free, low-smoke, flame-retardant cross-linked polyolefin in the insulating layer and the nylon cable material in the protective layer, the cable can delay explosion and combustion when the conductor is overloaded and short-circuited, resulting in high temperature.

[0019] In one embodiment, the insulating layer is wrapped around the conductor, and the protective layer is wrapped around the insulating layer.

[0020] In one embodiment, it further includes a glass fiber reinforcement layer; the insulation layer is divided into a first insulation layer and a second insulation layer; the first insulation layer is wrapped around the conductor, and the second insulation layer is wrapped around the glass fiber reinforcement layer.

[0021] In one embodiment, the glass fiber reinforcement layer includes a clockwise spiral glass fiber layer, a counterclockwise spiral glass fiber layer and a retaining layer; the clockwise spiral glass fiber layer and the counterclockwise spiral glass fiber layer are respectively placed inside or outside the retaining layer.

[0022] In one embodiment, the clockwise spiral glass fiber layer and the counterclockwise spiral glass fiber layer have the same thickness; the thickness of the retaining layer is at least three times that of the clockwise spiral glass fiber layer or the counterclockwise spiral glass fiber layer.

[0023] In one embodiment, the retaining layer is halogen-free, low-smoke, flame-retardant cross-linked polyolefin.

[0024] In one embodiment, it further includes a silicon carbide reinforcement wire; the silicon carbide reinforcement wire is spirally fused into the protective layer.

[0025] Also provided is a method for producing a cable capable of delayed explosion and combustion in the event of overload and short circuit, comprising the following steps:

[0026] S1: PA11 and PA66 are fully mixed in a blender to form a PA mixture;

[0027] S2: Transfer the PA mixture into the dryer for drying;

[0028] S2.1: Set the drying temperature of the dryer to 90°C and heat up for 5 minutes;

[0029] S2.2: Place the PA mixture in the dryer and bake for 4 minutes;

[0030] S3: Evenly mix the antioxidant and the anti-hydrolysis agent to form a mixed material;

[0031] S4: The PA mixture of S2 is transferred to a screw extruder, and the mixed component of S3 is added. The PA mixture and the mixed component are evenly mixed and extruded into pellets to form blended pellets;

[0032] S5: Insulation pellets made of halogen-free, low-smoke, flame-retardant cross-linked polyolefin;

[0033] S6: heating the conductor composed of annealed soft copper wire to 80-90°C;

[0034] S7: Wrapping a double-layer co-extruded covering layer on the conductor; loading the cable base wire in S6, the blended pellets in S4 and the insulating pellets in S5 into the extruder, heating the blended pellets and the insulating pellets separately, fusing them and wrapping them around the conductor, and extruding the finished cable wire;

[0035] S7.1: Install an axial flow air cooling device at least 1 m from the extrusion outlet of the extruder;

[0036] S7.2: Load the blended pellets in S4 into the second hopper of the extruder; load the insulation pellets in S5 into the first hopper of the extruder;

[0037] S7.3: Introduce the conductor in S6 into the cable inlet of the extruder;

[0038] S7.4: The extruder draws the insulation pellets and blended pellets in the first and second hoppers into the melt in the heating channel respectively;

[0039] S7.5: Feed the conductor of S7.3 first and pull out 1-2m of wire from the extruder to complete the pre-extrusion of the conductor. The conductor continues to be fed and passes through the cable channel of the co-extrusion die head.

[0040] Then, the S7.4 insulating pelletized melt is injected into the first coating channel, and the S7.4 blended pelletized melt is injected into the second coating channel. The first coating channel and the second coating channel are connected to the co-extrusion die head. The molten material flows into the co-extrusion die head. The insulating pelletized melt and the blended pelletized melt are formed into a double-layer structure in the co-extrusion die head through the internal flow channel according to the thickness ratio of the insulating layer and the protective layer. The insulating layer and the protective layer are layered and covered on the outer surface of the conductor cable blank.

[0041] S7.6: Pull the cable blank from S7.5 out of the extruder outlet to form a finished cable. Pass it through the axial flow air cooling device in S7.1 to cool it to room temperature.

[0042] S8: Apply talcum powder on the surface of the finished cable in S7 to prevent surface oxidation and reduce surface wear;

[0043] S9: Introduce the finished cable from S8 into the winding machine for winding and packaging.

[0044] Another method for producing a cable capable of delayed explosion and combustion in the event of an overload or short circuit is also provided. The method comprises the following steps: a preheating device, a first extruder, a first heat preservation device, a first weaving device, a second extruder, a second heat preservation device, a second weaving device, a third extruder, a fourth extruder, a third heat preservation device, a third weaving device, a fifth extruder, an axial flow air cooling device, and a talc powder coating device are sequentially arranged from the direction from the conductor entering to the discharge of the finished cable; the method comprises the following steps:

[0045] S1: PA11 and PA66 are fully mixed in a blender to form a PA mixture;

[0046] S2: Transfer the PA mixture into the dryer for drying;

[0047] S2.1: Set the drying temperature of the dryer to 90°C and heat up for 5 minutes;

[0048] S2.2: Place the PA mixture in the dryer and bake for 4 minutes;

[0049] S3: Evenly mix the antioxidant and the anti-hydrolysis agent to form a mixed material;

[0050] S4: The PA mixture of S2 is transferred to a screw extruder, and the mixed component of S3 is added. The PA mixture and the mixed component are evenly mixed and extruded into pellets to form blended pellets;

[0051] S5: Insulation pellets made of halogen-free, low-smoke, flame-retardant cross-linked polyolefin;

[0052] S6: introducing the conductor composed of annealed soft copper wire into the preheating device, and heating the conductor to 80-90°C while the conductor passes through the preheating device;

[0053] S7: Insulation pellets are loaded into the hopper of the first extruder, and the insulation pellets are melted and wrapped around the conductor of S6 by the first extruder to form a first insulation layer, and the first blank wire is pulled out from the discharge port;

[0054] S8: Insulation and wrapped with glass fiber reinforcement layer;

[0055] S8.1: Pass the first yarn from S7 through the first heat preservation device for heat preservation, and introduce it into the first weaving device. Wrap the first layer of spiral glass fiber around the first yarn in a clockwise or counterclockwise direction, and draw out the second yarn.

[0056] S8.2: Introduce the second wire in S8.1 into the cable inlet of the second extruder, load insulation pellets into the hopper of the second extruder, melt the insulation pellets and wrap them around the second wire to form a retaining layer, and pull out the third wire from the discharge port;

[0057] S8.3: The third yarn of S8.2 is introduced into the second heat-insulating device and then introduced into the second weaving device. A second layer of spiral glass fiber is wound around the third yarn in the opposite winding direction to S8.1, and a fourth yarn is pulled out.

[0058] S9: Introduce the fourth blank wire from S8.3 into the cable inlet of the third extruder, load insulation pellets into the hopper of the third extruder, melt the insulation pellets and wrap them around the second blank wire to form a second insulation layer, and pull out the fifth blank wire from the discharge port;

[0059] S10: Introduce the fifth billet wire of S9 into the cable inlet of the fourth extruder, load the blended pellets into the hopper of the fourth extruder, melt the blended pellets and wrap them around the fifth billet wire to form a first layer of protective layer, and pull out the sixth billet wire from the discharge port;

[0060] S11: The sixth base wire of S10 is introduced into the third heat preservation device and then introduced into the third weaving device, and the silicon carbide reinforcing wire is spirally wound on the sixth base wire in a clockwise or counterclockwise direction to pull out the seventh base wire;

[0061] S12: Introduce the seventh base wire of S11 into the cable inlet of the fifth extruder, load the blended pellets into the hopper of the fifth extruder, melt the blended pellets and wrap them around the seventh base wire to form a second protective layer, and pull out the cable base wire from the discharge port;

[0062] S13: The cable blank wire of S12 is passed through an axial flow air cooling device to cool the cable blank wire to obtain a finished cable wire;

[0063] S14: The finished cable wire of S13 is passed through a talcum powder coating machine, and talcum powder is coated on the finished cable wire to slow down the oxidation of the surface of the finished cable wire and reduce the surface wear;

[0064] S15: The finished cable of S14 is introduced into the winding machine for winding and packaging.

[0065] The beneficial effects of the present invention are as follows:

[0066] (1) Realization of delayed burst performance

[0067] The protective layer of the cable is made of nylon cable material composed of PA11 and PA66 in a ratio of 90% and 9%, with antioxidants and anti-hydrolysis agents added. The protective layer has the following excellent properties: high toughness and impact resistance. Since PA11 and PA66 are both polymer materials, they can maintain the integrity of the cable structure under the high temperature and mechanical stress generated when the cable is overloaded and short-circuited, effectively delaying the occurrence of bursting.

[0068] Antioxidation and hydrolysis resistance: The addition of antioxidants and anti-hydrolysis agents enhances the stability of the nylon material of the protective layer in high temperature and humid environments, preventing the material performance from being reduced due to environmental deterioration, thereby further improving the delayed burst performance.

[0069] Thermoplasticity: Thermoplasticity enables nylon to absorb some of the heat energy when heated, avoiding the direct concentration of heat energy in a local area and reducing the possibility of rapid disintegration of the material.

[0070] Through the optimized combination of PA11, PA66, antioxidants and anti-hydrolysis agents, the cable can maintain the integrity of its outer layer for a certain period of time in a high-temperature environment caused by overload and short circuit, that is, the integrity of the protective layer is maintained for a certain period of time, thereby achieving the cable's extended burst performance; effectively avoiding spark or arc leakage caused by the burst of the cable's protective layer, thereby ensuring the safety of the power room or line environment.

[0071] (2) Realization of delayed combustion performance

[0072] The insulation layer is made of halogen-free, low-smoke, flame-retardant cross-linked polyolefin, which has excellent flame retardant properties and environmental friendliness. Under high temperature conditions caused by overload and short circuit, the halogen-free, low-smoke, flame-retardant cross-linked polyolefin can quickly form a carbonized layer, isolate the oxygen supply, slow down the spread of combustion, and achieve delayed combustion performance of the cable, thereby further improving the delayed burst effect of the cable.

[0073] The cross-linked structure of halogen-free, low-smoke flame-retardant cross-linked polyolefin can enhance thermal stability: after the molecular chain of the cross-linked polyolefin is cross-linked, the heat resistance is greatly improved, and it can maintain structural stability for a long time under high temperature conditions, avoiding accelerated combustion due to material decomposition.

[0074] And due to its low-smoke and halogen-free properties, it produces very little smoke during combustion and no corrosive and toxic gases. It is suitable for use in confined spaces or high-risk places (such as subways and chemical plants), effectively reducing secondary hazards in fires.

[0075] The double-layer co-extrusion covering structure of the insulation layer and the protective layer further improves the delayed combustion performance, ensuring that the heat energy can be transferred and dissipated layer by layer under the high temperature caused by overload and short circuit of the cable, thereby delaying the occurrence and spread of combustion.

[0076] (3) The synergistic effect of the double-layer co-extrusion covering structure. The insulation layer and the protective layer adopt a double-layer co-extrusion covering structure, which enables the insulation and protective materials of the cable to achieve better sealing and uniformity on the conductor, further improving the overall delayed burst and delayed combustion performance of the cable; among them, the sealing is enhanced, and the co-extrusion process ensures the close combination of the insulation layer and the protective layer, avoiding interlayer peeling or cracking due to high temperature or impact during overload and short circuit. The heat shielding effect is enhanced. The insulation layer and the protective layer jointly form a heat barrier, gradually absorbing heat energy under high temperature conditions, avoiding rapid temperature rise in a short period of time to cause bursting or combustion. The protective layer can enhance the protective effect. Even if the insulation layer is partially damaged during overload and short circuit, the protective layer can still provide additional protection, thereby enhancing the overall reliability and safety.

[0077] This structural design ensures maximum utilization of material performance, extends the failure time of the cable under extreme conditions, and buys valuable time for taking further safety measures.

[0078] The present invention selects halogen-free low-smoke flame-retardant cross-linked polyolefin and nylon cable materials as the main materials and adopts a double-layer co-extrusion covering structure, thereby achieving a long-term delayed burst and delayed combustion performance of the cable under overload and short-circuit conditions; significantly improving the safety and reliability of the cable; the produced cable with delayed burst and delayed combustion is particularly suitable for industrial, construction and public facility environments with high cable safety requirements, and has broad application prospects and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are only some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0080] Figure 1 is a schematic cross-sectional view of a cable according to a first embodiment of the present invention;

[0081] Figure 2 2 is a schematic diagram of the cross-sectional structure of a cable according to the second embodiment of the present invention.

[0082] The accompanying drawings are numerals as follows:

[0083] 1. Conductor;

[0084] 2. Insulation layer; 21. First insulation layer; 22. Second insulation layer;

[0085] 3. Protective layer;

[0086] 4. Double-layer co-extrusion cover layer;

[0087] 5. Glass fiber reinforcement layer; 51. Clockwise spiral glass fiber layer; 52. Counterclockwise spiral glass fiber layer; 53. Retention layer;

[0088] 6. Silicon carbide reinforcement wire. DETAILED DESCRIPTION

[0089] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0090] In a specific embodiment, a cable is provided that can delay bursting and burning in the event of an overload and short circuit. By combining the halogen-free, low-smoke, flame-retardant cross-linked polyolefin of the insulation layer and the nylon cable material of the protective layer, the cable can be delayed in bursting after a high temperature is caused by a short circuit in the conductor, thereby prolonging the time for external oxygen to contact the insulation layer, thereby achieving the effect of delayed combustion. This effectively solves the problem that existing explosion-delayed flame-retardant cables do not have the performance of delayed bursting and delayed combustion for a long time in the event of an overload and short circuit.

[0091] In addition, all the contents of the configurations shown in the following embodiments are not necessarily essential as the solution to the invention described in the claims.

[0092] The first implementation of a cable that bursts and burns with a time delay in the event of an overload or short circuit is Figure 1 As shown, it includes a conductor 1: annealed soft copper wire; an insulating layer 2: halogen-free, low-smoke, flame-retardant cross-linked polyolefin; and a protective layer 3: nylon cable material; wherein the nylon cable material is composed of a mass ratio of PA11: 90%, PA66: 9%, antioxidant: 0.5%, and anti-hydrolysis agent: 0.5%; the insulating layer 2 and the protective layer 3 form a double-layer co-extruded covering layer 4 wrapped around the conductor 1. Through the combination of the halogen-free, low-smoke, flame-retardant cross-linked polyolefin of the insulating layer 2 and the nylon cable material of the protective layer 3, after the conductor 1 is short-circuited and causes high temperature, the cable will be delayed in bursting and burning.

[0093] Specifically, the insulating layer 2 is wrapped around the conductor 1 , and the protective layer 3 is wrapped around the insulating layer 2 .

[0094] The thickness ratio of the insulating layer 2 to the protective layer 3 is 2:1.

[0095] The protective layer of the cable is made of nylon cable material composed of PA11 and PA66 in a ratio of 90% and 9%, with antioxidants and anti-hydrolysis agents added. The protective layer has the following excellent properties: high toughness and impact resistance. Since PA11 and PA66 are both polymer materials, they can maintain the integrity of the cable structure under the high temperature and mechanical stress generated when the cable is overloaded and short-circuited, effectively delaying the occurrence of bursting.

[0096] Antioxidation and hydrolysis resistance: The addition of antioxidants and anti-hydrolysis agents enhances the stability of the nylon material of the protective layer in high temperature and humid environments, preventing the material performance from being reduced due to environmental deterioration, thereby further improving the delayed burst performance.

[0097] Thermoplasticity: Thermoplasticity enables nylon to absorb some of the heat energy when heated, avoiding the direct concentration of heat energy in a local area and reducing the possibility of rapid disintegration of the material.

[0098] Through the optimized combination of PA11, PA66, antioxidants and anti-hydrolysis agents, the cable can maintain the integrity of its outer layer for a certain period of time in a high-temperature environment caused by overload and short circuit, that is, the integrity of the protective layer is maintained for a certain period of time, thereby achieving the cable's extended burst performance; effectively avoiding spark or arc leakage caused by the burst of the cable's protective layer, thereby ensuring the safety of the power room or line environment.

[0099] The insulation layer is made of halogen-free, low-smoke, flame-retardant cross-linked polyolefin, which has excellent flame retardant properties and environmental friendliness. Under high temperature conditions caused by overload and short circuit, the halogen-free, low-smoke, flame-retardant cross-linked polyolefin can quickly form a carbonized layer, isolate the oxygen supply, slow down the spread of combustion, and achieve delayed combustion performance of the cable, thereby further improving the delayed burst effect of the cable.

[0100] The cross-linked structure of halogen-free, low-smoke flame-retardant cross-linked polyolefin can enhance thermal stability: after the molecular chain of the cross-linked polyolefin is cross-linked, the heat resistance is greatly improved, and it can maintain structural stability for a long time under high temperature conditions, avoiding accelerated combustion due to material decomposition.

[0101] And due to its low-smoke and halogen-free properties, it produces very little smoke during combustion and no corrosive and toxic gases. It is suitable for use in confined spaces or high-risk places (such as subways and chemical plants), effectively reducing secondary hazards in fires.

[0102] The double-layer co-extrusion covering structure of the insulation layer and the protective layer further improves the delayed combustion performance, ensuring that the heat energy can be transferred and dissipated layer by layer under the high temperature caused by overload and short circuit of the cable, thereby delaying the occurrence and spread of combustion.

[0103] The double-layer co-extrusion covering structure has a synergistic effect: the insulation layer and the protective layer adopt a double-layer co-extrusion covering structure, which enables the insulation and protective materials of the cable to achieve better sealing and uniformity on the conductor, further improving the overall delayed burst and delayed combustion performance of the cable; among them, the sealing is enhanced, and the co-extrusion process ensures the close bonding of the insulation layer and the protective layer, avoiding interlayer peeling or cracking due to high temperature or impact during overload and short circuit. The thermal shielding effect is enhanced. The insulation layer and the protective layer together form a thermal barrier, gradually absorbing heat energy under high temperature conditions, avoiding rapid temperature rise in a short period of time that causes bursting or combustion. The protective layer can enhance the protective effect. Even if the insulation layer is partially damaged during an overload and short circuit, the protective layer can still provide additional protection, thereby enhancing overall reliability and safety.

[0104] Based on the first embodiment of the cable that explodes and burns with a time delay under overload and short circuit conditions, a method for producing the cable is provided, comprising the following steps:

[0105] S1: PA11 and PA66 are fully mixed in a blender to form a PA mixture;

[0106] S2: Transfer the PA mixture into the dryer for drying;

[0107] S2.1: Set the drying temperature of the dryer to 90°C and heat up for 5 minutes;

[0108] S2.2: Place the PA mixture in the dryer and bake for 4 minutes;

[0109] S3: Evenly mix the antioxidant and the anti-hydrolysis agent to form a mixed material;

[0110] S4: The PA mixture of S2 is transferred to a screw extruder, and the mixed component of S3 is added. The PA mixture and the mixed component are evenly mixed and extruded into pellets to form blended pellets;

[0111] S5: Insulation pellets made of halogen-free, low-smoke, flame-retardant cross-linked polyolefin;

[0112] S6: heating the conductor composed of annealed soft copper wire to 80-90°C;

[0113] S7: Wrapping a double-layer co-extruded covering layer on the conductor; loading the cable base wire in S6, the blended pellets in S4 and the insulating pellets in S5 into the extruder, heating the blended pellets and the insulating pellets separately, fusing them and wrapping them around the conductor, and extruding the finished cable wire;

[0114] S7.1: Install an axial flow air cooling device at least 1 m from the extrusion outlet of the extruder;

[0115] S7.2: Load the blended pellets in S4 into the second hopper of the extruder; load the insulation pellets in S5 into the first hopper of the extruder;

[0116] S7.3: Introduce the conductor in S6 into the cable inlet of the extruder;

[0117] S7.4: The extruder draws the insulation pellets and blended pellets in the first and second hoppers into the melt in the heating channel respectively;

[0118] S7.5: Feed the conductor of S7.3 first and pull out 1-2m of wire from the extruder to complete the pre-extrusion of the conductor. The conductor continues to be fed and passes through the cable channel of the co-extrusion die head.

[0119] Then, the S7.4 insulating pelletized melt is injected into the first coating channel, and the S7.4 blended pelletized melt is injected into the second coating channel. The first coating channel and the second coating channel are connected to the co-extrusion die head. The molten material flows into the co-extrusion die head. The insulating pelletized melt and the blended pelletized melt are formed into a double-layer structure in the co-extrusion die head through the internal flow channel according to the thickness ratio of the insulating layer and the protective layer. The insulating layer and the protective layer are layered and covered on the outer surface of the conductor cable blank.

[0120] S7.6: Pull the cable blank from S7.5 out of the extruder outlet to form a finished cable. Pass it through the axial flow air cooling device in S7.1 to cool it to room temperature.

[0121] S8: Apply talcum powder on the surface of the finished cable in S7 to prevent surface oxidation and reduce surface wear;

[0122] S9: Introduce the finished cable from S8 into the winding machine for winding and packaging.

[0123] During application, the temperature of the first coating channel is set to 190-200°C, and the temperature of the second coating channel is set to 260-270°C.

[0124] The second embodiment of the cable that bursts and burns with time delay in case of overload and short circuit is as follows Figure 2 As shown, the difference between this embodiment and the first embodiment is that it further includes a glass fiber reinforcement layer 5; the insulation layer 2 is divided into a first insulation layer 21 and a second insulation layer 22; the first insulation layer 21 is wrapped around the conductor 1, and the second insulation layer 22 is wrapped around the glass fiber reinforcement layer 5.

[0125] Specifically, the glass fiber reinforcement layer 5 includes a clockwise spiral glass fiber layer 51 , a counterclockwise spiral glass fiber layer 52 and a retaining layer 53 ; the clockwise spiral glass fiber layer 51 and the counterclockwise spiral glass fiber layer 52 are respectively placed inside or outside the retaining layer 53 .

[0126] During application, the heat insulation performance of glass fiber is utilized, and a double layer of glass fiber with a reverse spiral is provided to attenuate the heat transfer layer by layer. The double layer of glass fiber with a reverse spiral direction further enhances the mechanical strength of the insulating layer 2.

[0127] Among them, the cross-sectional positions of the clockwise spiral glass fiber layer 51 and the counterclockwise spiral glass fiber layer 52 are staggered. After being formed on the retaining layer 53, the structural stress exerted by the clockwise spiral glass fiber layer 51 and the counterclockwise spiral glass fiber layer 52 on the retaining layer 53 can be reduced.

[0128] Regarding the thickness ratio of the above-mentioned clockwise spiral glass fiber layer 51, counterclockwise spiral glass fiber layer 52 and retaining layer 53, the thickness of the clockwise spiral glass fiber layer 51 is the same as that of the counterclockwise spiral glass fiber layer 52; the thickness of the retaining layer 53 is at least 3 times that of the clockwise spiral glass fiber layer 51 or the counterclockwise spiral glass fiber layer 52.

[0129] The retaining layer 53 is made of halogen-free, low-smoke, flame-retardant cross-linked polyolefin.

[0130] In addition, silicon carbide reinforcement wires 6 are also included; the silicon carbide reinforcement wires 6 are spirally integrated into the protective layer 3 .

[0131] When used, silicon carbide reinforced wire 6 has excellent mechanical properties, high temperature resistance and corrosion resistance, but the price is relatively high. The cables with delayed burst and delayed combustion made of silicon carbide reinforced wire 6 are generally only used in high-risk chemical fields.

[0132] By adding a glass fiber reinforcement layer 5 and adding a silicon carbide reinforcement wire 6 to the protective layer 3, the mechanical properties and internal high-temperature performance of the finished cable are enhanced, and a reinforced delayed burst and delayed combustion cable is achieved. It can avoid the finished cable from bursting when the overload protection layer 3 occurs, and achieve a longer delayed combustion performance.

[0133] Based on the second embodiment of the cable with delayed bursting and burning under overload and short circuit conditions, a method for producing a reinforced cable with delayed bursting and burning is provided, wherein a preheating device, a first extruder, a first heat preservation device, a first weaving device, a second extruder, a second heat preservation device, a second weaving device, a third extruder, a fourth extruder, a third heat preservation device, a third weaving device, a fifth extruder, an axial flow air cooling device, and a talc powder coating device are sequentially arranged in the direction from conductor entry to finished cable discharge;

[0134] The method comprises the following steps: S1: fully mixing PA11 and PA66 in a blender to form a PA mixture;

[0135] S2: Transfer the PA mixture into the dryer for drying;

[0136] S2.1: Set the drying temperature of the dryer to 90°C and heat up for 5 minutes;

[0137] S2.2: Place the PA mixture in the dryer and bake for 4 minutes;

[0138] S3: Evenly mix the antioxidant and the anti-hydrolysis agent to form a mixed material;

[0139] S4: The PA mixture of S2 is transferred to a screw extruder, and the mixed component of S3 is added. The PA mixture and the mixed component are evenly mixed and extruded into pellets to form blended pellets;

[0140] S5: Insulation pellets made of halogen-free, low-smoke, flame-retardant cross-linked polyolefin;

[0141] S6: introducing the conductor composed of annealed soft copper wire into the preheating device, and heating the conductor to 80-90°C while the conductor passes through the preheating device;

[0142] S7: Insulation pellets are loaded into the hopper of the first extruder, and the insulation pellets are melted and wrapped around the conductor of S6 by the first extruder to form a first insulation layer, and the first blank wire is pulled out from the discharge port;

[0143] S8: Insulation and wrapped with glass fiber reinforcement layer;

[0144] S8.1: Pass the first yarn from S7 through the first heat preservation device for heat preservation, and introduce it into the first weaving device. Wrap the first layer of spiral glass fiber around the first yarn in a clockwise or counterclockwise direction, and draw out the second yarn.

[0145] S8.2: Introduce the second wire in S8.1 into the cable inlet of the second extruder, load insulation pellets into the hopper of the second extruder, melt the insulation pellets and wrap them around the second wire to form a retaining layer, and pull out the third wire from the discharge port;

[0146] S8.3: The third yarn of S8.2 is introduced into the second heat-insulating device and then introduced into the second weaving device. A second layer of spiral glass fiber is wound around the third yarn in the opposite winding direction to S8.1, and a fourth yarn is pulled out.

[0147] S9: Introduce the fourth blank wire from S8.3 into the cable inlet of the third extruder, load insulation pellets into the hopper of the third extruder, melt the insulation pellets and wrap them around the second blank wire to form a second insulation layer, and pull out the fifth blank wire from the discharge port;

[0148] S10: Introduce the fifth billet wire of S9 into the cable inlet of the fourth extruder, load the blended pellets into the hopper of the fourth extruder, melt the blended pellets and wrap them around the fifth billet wire to form a first layer of protective layer, and pull out the sixth billet wire from the discharge port;

[0149] S11: The sixth base wire of S10 is introduced into the third heat preservation device and then introduced into the third weaving device, and the silicon carbide reinforcing wire is spirally wound on the sixth base wire in a clockwise or counterclockwise direction to pull out the seventh base wire;

[0150] S12: Introduce the seventh base wire of S11 into the cable inlet of the fifth extruder, load the blended pellets into the hopper of the fifth extruder, melt the blended pellets and wrap them around the seventh base wire to form a second protective layer, and pull out the cable base wire from the discharge port;

[0151] S13: The cable blank wire of S12 is passed through an axial flow air cooling device to cool the cable blank wire to obtain a finished cable wire;

[0152] S14: The finished cable wire of S13 is passed through a talcum powder coating machine, and talcum powder is coated on the finished cable wire to slow down the oxidation of the surface of the finished cable wire and reduce the surface wear;

[0153] S15: The finished cable of S14 is introduced into the winding machine for winding and packaging.

[0154] The finished cables made using the composition, structure, and production method of the first embodiment, and the finished cables made using the composition, structure, and production method of the second embodiment, were subjected to a short-term high current exceeding 50-80% of the critical current of the finished cables. The experimental results are shown in the following table:

[0155]

[0156] From the above experimental results, it can be seen that the finished cable of the first embodiment, which only has an insulating layer and a protective layer, can withstand a current of 1.8 times the maximum critical current for at least 2 minutes without bursting or burning. This means that the finished cable takes at least 2 minutes to burst or burn. The finished cable of the second embodiment, by adding a glass fiber reinforcement layer that provides thermal insulation, a glass fiber reinforcement layer that increases the mechanical strength of the insulating layer, and a silicon carbide reinforcement wire that increases the mechanical strength of the protective layer, does not burst even under a short-term high current of 1.8 times the critical current, but it does fail by melting. Compared with the first embodiment, the delayed failure time of the protective layer of the finished cable is significantly increased, and the contact of external oxygen with the insulating layer is delayed, thereby greatly improving the delayed combustion time of the insulating layer.

[0157] The technical features of the above embodiments may be arbitrarily combined. To simplify the description, not all possible combinations of the technical features in the above embodiments are described.

Claims

1. A cable that explodes and burns with a time delay under overload and short circuit conditions, characterized in that: Including conductor: annealed soft copper wire; And insulation layer: halogen-free, low-smoke, flame-retardant cross-linked polyolefin; And a protective layer: nylon cable material; wherein the nylon cable material is composed of a mass ratio of PA11: 90%, PA66: 9%, antioxidant: 0.5%, and anti-hydrolysis agent: 0.5%; The insulating layer and the protective layer form a double-layer co-extruded covering layer wrapped around the conductor. Through the combination of the halogen-free low-smoke flame-retardant cross-linked polyolefin of the insulating layer and the nylon cable material of the protective layer, when the conductor is overloaded and short-circuited, resulting in high temperature, the cable will explode and burn with time. The insulating layer is wrapped around the conductor, and the protective layer is wrapped around the insulating layer; It also includes a glass fiber reinforcement layer; the insulation layer is divided into a first insulation layer and a second insulation layer; the first insulation layer is wrapped around the conductor, and the second insulation layer is wrapped around the glass fiber reinforcement layer; The glass fiber reinforcement layer includes a clockwise spiral glass fiber layer, a counterclockwise spiral glass fiber layer and a retaining layer; the clockwise spiral glass fiber layer and the counterclockwise spiral glass fiber layer are respectively placed inside or outside the retaining layer; The clockwise spiral glass fiber layer and the counterclockwise spiral glass fiber layer have the same thickness; the thickness of the retaining layer is at least 3 times that of the clockwise spiral glass fiber layer or the counterclockwise spiral glass fiber layer; The retaining layer is made of halogen-free, low-smoke, flame-retardant cross-linked polyolefin; It also includes silicon carbide reinforcement wires; the silicon carbide reinforcement wires are spirally fused into the protective layer.

2. A method for producing a cable capable of delayed explosion and combustion under overload and short circuit conditions according to claim 1, characterized in that: The following steps are involved: S1: PA11 and PA66 are fully mixed in a blender to form a PA mixture; S2: Transfer the PA mixture into the dryer for drying; S2.1: Set the drying temperature of the dryer to 90°C and heat up for 5 minutes; S2.2: Place the PA mixture in the dryer and bake for 4 minutes; S3: Evenly mix the antioxidant and the anti-hydrolysis agent to form a mixed material; S4: The PA mixture of S2 is transferred to a screw extruder, and the mixed component of S3 is added. The PA mixture and the mixed component are evenly mixed and extruded into pellets to form blended pellets; S5: Insulation pellets made of halogen-free, low-smoke, flame-retardant cross-linked polyolefin; S6: heating the conductor composed of annealed soft copper wire to 80-90°C; S7: Wrapping a double-layer co-extruded covering layer on the conductor; loading the cable base wire in S6, the blended pellets in S4 and the insulating pellets in S5 into the extruder, heating the blended pellets and the insulating pellets separately, fusing them and wrapping them around the conductor, and extruding the finished cable wire; S7.1: Install an axial flow air cooling device at least 1 m from the extrusion outlet of the extruder; S7.2: Load the blended pellets from S4 into the second hopper of the extruder; The insulation pellets in S5 are loaded into the first hopper of the extruder; S7.3: Introduce the conductor in S6 into the cable inlet of the extruder; S7.4: The extruder draws the insulation pellets and blended pellets in the first and second hoppers into the melt in the heating channel respectively; S7.5: Feed the conductor of S7.3 first and pull out 1-2m of wire from the extruder to complete the pre-extrusion of the conductor. The conductor continues to be fed and passes through the cable channel of the co-extrusion die head. Then, the S7.4 insulating pelletized melt is injected into the first coating channel, and the S7.4 blended pelletized melt is injected into the second coating channel. The first coating channel and the second coating channel are connected to the co-extrusion die head. The molten material flows into the co-extrusion die head. The insulating pelletized melt and the blended pelletized melt are formed into a double-layer structure in the co-extrusion die head through the internal flow channel according to the thickness ratio of the insulating layer and the protective layer. The insulating layer and the protective layer are covered on the outer surface of the conductor cable blank in layers. S7.6: Pull the cable blank from S7.5 out of the extruder outlet to form a finished cable. Pass it through the axial flow air cooling device in S7.1 to cool it to room temperature. S8: Apply talcum powder on the surface of the finished cable in S7 to prevent surface oxidation and reduce surface wear; S9: Introduce the finished cable from S8 into the winding machine for winding and packaging.

3. A method for producing a cable capable of delayed explosion and combustion under overload and short circuit conditions according to claim 1, characterized in that: According to the direction from conductor entry to finished cable discharge, a preheating device, a first extruder, a first heat preservation device, a first weaving device, a second extruder, a second heat preservation device, a second weaving device, a third extruder, a fourth extruder, a third heat preservation device, a third weaving device, a fifth extruder, an axial flow air cooling device and a talc powder coating machine are sequentially arranged; The following steps are involved: S1: PA11 and PA66 are fully mixed in a blender to form a PA mixture; S2: Transfer the PA mixture into the dryer for drying; S2.1: Set the drying temperature of the dryer to 90°C and heat up for 5 minutes; S2.2: Place the PA mixture in the dryer and bake for 4 minutes; S3: Evenly mix the antioxidant and the anti-hydrolysis agent to form a mixed material; S4: The PA mixture of S2 is transferred to a screw extruder, and the mixed component of S3 is added. The PA mixture and the mixed component are evenly mixed and extruded into pellets to form blended pellets; S5: Insulation pellets made of halogen-free, low-smoke, flame-retardant cross-linked polyolefin; S6: introducing the conductor composed of annealed soft copper wire into the preheating device, and heating the conductor to 80-90°C while the conductor passes through the preheating device; S7: Insulation pellets are loaded into the hopper of the first extruder, and the insulation pellets are melted and wrapped around the conductor of S6 by the first extruder to form a first insulation layer, and the first blank wire is pulled out from the discharge port; S8: Insulation and wrapped with glass fiber reinforcement layer; S8.1: Pass the first yarn from S7 through the first heat preservation device for heat preservation, and introduce it into the first weaving device. Wrap the first layer of spiral glass fiber around the first yarn in a clockwise or counterclockwise direction, and draw out the second yarn. S8.2: Introduce the second wire in S8.1 into the cable inlet of the second extruder, load insulation pellets into the hopper of the second extruder, melt the insulation pellets and wrap them around the second wire to form a retaining layer, and pull out the third wire from the discharge port; S8.3: The third yarn of S8.2 is introduced into the second heat-insulating device and then introduced into the second weaving device. A second layer of spiral glass fiber is wound around the third yarn in the opposite winding direction to S8.1, and a fourth yarn is pulled out. S9: Introduce the fourth blank wire from S8.3 into the cable inlet of the third extruder, load insulation pellets into the hopper of the third extruder, melt the insulation pellets and wrap them around the second blank wire to form a second insulation layer, and pull out the fifth blank wire from the discharge port; S10: Introduce the fifth billet wire of S9 into the cable inlet of the fourth extruder, load the blended pellets into the hopper of the fourth extruder, melt the blended pellets and wrap them around the fifth billet wire to form a first layer of protective layer, and pull out the sixth billet wire from the discharge port; S11: The sixth base wire of S10 is introduced into the third heat preservation device and then introduced into the third weaving device, and the silicon carbide reinforcing wire is spirally wound on the sixth base wire in a clockwise or counterclockwise direction to pull out the seventh base wire; S12: Introduce the seventh base wire of S11 into the cable inlet of the fifth extruder, load the blended pellets into the hopper of the fifth extruder, melt the blended pellets and wrap them around the seventh base wire to form a second protective layer, and pull out the cable base wire from the discharge port; S13: The cable blank wire of S12 is passed through an axial flow air cooling device to cool the cable blank wire to obtain a finished cable wire; S14: The finished cable wire of S13 is passed through a talcum powder coating machine, and talcum powder is coated on the finished cable wire to slow down the oxidation of the surface of the finished cable wire and reduce the surface wear; S15: The finished cable of S14 is introduced into the winding machine for winding and packaging.

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