Cable capable of delaying burst and combustion under overload short circuit condition and production method

Abstract

The invention discloses a cable capable of delaying burst and combustion under overload and short circuit conditions and a production method, and relates to the technical field of cables, the cable takes an annealed annealed copper wire as a conductor, takes halogen-free low-smoke flame-retardant cross-linked polyolefin as an insulating layer, and takes a nylon cable material as a protective layer; wherein the nylon cable material is prepared from the following components in percentage by mass: 90% of PA11, 9% of PA66, 0.5% of an antioxidant and 0.5% of an anti-hydrolysis agent; the insulating layer and the protective layer form a double-layer co-extrusion covering layer which is wrapped outside the conductor; according to the invention, through the cooperation of the halogen-free low-smoke flame-retardant cross-linked polyolefin of the insulating layer and the nylon cable material of the protective layer, after the conductor is overloaded and short-circuited to cause high temperature, the cable is delayed to burst, and the contact time of external oxygen in the insulating layer is prolonged, so that the effect of delayed combustion is realized; the problem that an existing explosion-delay flame-retardant cable does not have long-time explosion-delay and combustion-delay performance under the overload short circuit condition is solved.

Description

Technical Field

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

[0002] With the rapid development of industrialization and urbanization, the electrification degree of various buildings and facilities is constantly improving. However, as the core component of power transmission, cables face complex environments and potential dangers during use, such as high temperature, mechanical shock, chemical corrosion and fire. In particular, in summer or under extreme working conditions, short-term excessive current may cause local high temperature of the cable, causing the cable to burst and burn. In these cases, the performance of traditional cables may not be sufficient to cope with harsh conditions, making it difficult to effectively ensure the safe operation of facilities and personal safety.

[0003] In fire accidents, cables are often an important factor in the source of fire or the spread of fire. For example, when cable materials burn, they release high-temperature flames, toxic smoke and corrosive gases, which not only endanger life safety, but may also cause damage to secondary equipment. In addition, in flammable and explosive places, such as petrochemicals and mines, sparks or high temperatures generated by cables may directly cause explosions. Therefore, it is an inevitable demand to develop cables with both delayed burst and delayed combustion functions.

[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 functionality at high temperatures.

[0007] (3) Anti-mechanical impact technology: Use metal armor and high-strength outer sheath to enhance the cable's impact 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 down the spread of flames by adding flame retardants (such as aluminum hydroxide, magnesium hydroxide, etc.) to the outer sheath or insulation layer. Flame-retardant cables are divided into single flame-retardant type and low-smoke halogen-free flame-retardant type. Low-smoke halogen-free materials are more environmentally friendly and reduce toxicity and corrosiveness during combustion.

[0011] The delayed burst characteristics of explosion-retardant cables are achieved through a multi-layer structure, such as metal armor, pressure-resistant sheath and tensile core wire. This design can effectively cope with mechanical shock, high pressure and environmental stress, ensuring that the cable will not break or leak external sparks.

[0012] Although the current 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. Current high-voltage and low-voltage power rooms are equipped with intelligent monitoring. Therefore, if electronic components have a delay function under extreme working conditions, when an overload and short circuit occurs, they will not burn immediately due to high temperature, but will delay burst and combustion within a certain delay time, so that intelligent monitoring can have enough time to warn when uncontrollable failures occur in electronic components; and 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, the application of this technology 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 prior art 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 with delayed explosion and combustion under overload and short circuit conditions, so as to solve 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 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 capable of delayed explosion and combustion under overload and short circuit conditions, comprising a conductor: annealed soft copper wire; an insulating 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%, 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 wrapped around the conductor, and 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, the cable can be delayed to explode and burn after the conductor is overloaded and short-circuited to cause 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 of the embodiments, 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.

[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 has the same thickness as the counterclockwise spiral glass fiber layer; and 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 of the embodiments, 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 bursting and burning in the case of overload and short circuit, comprising the following steps:

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

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

[0028] S2.1: The drying temperature of the dryer is set to 90°C and the machine is heated for 5 minutes;

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

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

[0031] S4: The PA mixture of S2 is transferred into a screw extruder, and the mixed material of S3 is added, and the PA mixture and the mixed material are mixed and evenly extruded and pelletized to form mixed 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 blank 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 respectively, fusing them and wrapping them outside the conductor, and extruding and pulling out the finished cable wire;

[0035] S7.1: An axial air cooling device shall be installed 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 rolls the insulation pellets and the blended pellets in the first hopper and the second hopper into the melt in the heating channel respectively;

[0039] S7.5: Feed the conductor of S7.3 first, and pull out the wire 1-2m from the extrusion outlet to complete the pre-pulling 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, and 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 cable blank wire of the conductor in layers;

[0041] S7.6: Pull the cable blank wire of S7.5 out of the discharge port of the extruder to form a finished cable wire, pass it through the axial flow air cooling device of S7.1, and cool the finished cable wire to room temperature;

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

[0043] S9: Introduce the finished cable wire of S8 into the winding machine and reel it for packaging.

[0044] Another method for producing a cable capable of delayed explosion and combustion under overload and short circuit conditions is also 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 talcum powder coating machine are sequentially arranged in a direction from the conductor entering to the finished cable discharging; the method comprises the following steps:

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

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

[0047] S2.1: The drying temperature of the dryer is set to 90°C and the machine is heated for 5 minutes;

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

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

[0050] S4: The PA mixture of S2 is transferred into a screw extruder, and the mixed material of S3 is added, and the PA mixture and the mixed material are mixed and evenly extruded and pelletized to form mixed 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 a preheating device, and heating the conductor to 80-90° C. when the conductor passes through the preheating device;

[0053] S7: loading the insulating pellets into the hopper of the first extruder, melting the insulating pellets through the first extruder and wrapping them around the conductor of S6 to form a first insulating layer, and pulling out the first blank wire from the discharge port;

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

[0055] S8.1: passing the first blank wire of S7 through the first heat preservation device for heat preservation, and introducing it into the first weaving device, winding the first layer of spiral glass fiber on the first blank wire in a clockwise or counterclockwise direction, and pulling out the second blank wire;

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

[0057] S8.3: The third blank wire of S8.2 is introduced into the second heat preservation device and then introduced into the second weaving device, and the second layer of spiral glass fiber is wound on the third blank wire in the opposite winding direction to S8.1, and the fourth blank wire is pulled out;

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

[0059] S10: Introduce the fifth blank 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 outside the fifth blank wire to form a first layer of protective layer, and pull out the sixth blank wire from the discharge port;

[0060] S11: introducing the sixth blank wire of S10 into the third heat preservation device, and then introducing it into the third weaving device, spirally winding the silicon carbide reinforcing wire on the sixth blank wire in a clockwise or counterclockwise direction, and pulling out the seventh blank wire;

[0061] S12: Introduce the seventh blank 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 blank wire to form a second protective layer, and pull out the cable blank wire from the discharge port;

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

[0063] S14: passing the finished cable wire of S13 through a talcum powder coating machine, and coating the finished cable wire with talcum powder, so that the surface oxidation of the finished cable wire is slowed down and the surface wear is reduced;

[0064] S15: Introduce the finished cable wire of S14 into the winding machine and wrap it.

[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] Anti-oxidation 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 heat 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 part 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 extension and burst performance of the cable; effectively avoiding the spark or arc leakage caused by the burst of the protective layer of the cable, 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 protection. Under high temperature conditions caused by overload and short circuit, halogen-free, low-smoke, flame-retardant cross-linked polyolefin can quickly form a carbonized layer, isolate the oxygen supply, delay 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 thermal barrier, which gradually absorbs heat energy under high temperature conditions to avoid rapid temperature rise in a short period of time to cause burst 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 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; the safety and reliability of the cable are significantly improved, and the produced delayed burst and delayed combustion cables are particularly suitable for industrial, construction and public facility environments with high cable safety requirements, and have 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 drawings required for use in the implementation mode will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

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

[0082] The reference numerals are 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 covering 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 reinforced wire. DETAILED DESCRIPTION

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

[0090] A specific embodiment provides a cable that can delay bursting and burning in the event of an overload and short circuit. Through the combination of halogen-free, low-smoke, flame-retardant cross-linked polyolefin in the insulating layer and nylon cable material in the protective layer, the cable can be delayed in bursting after the conductor is short-circuited and the high temperature is caused, thereby prolonging the time for external oxygen to contact the insulating layer, thereby achieving the effect of delayed combustion. This effectively solves the problem that the existing delayed explosion and 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 limited to the solutions of 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 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, and through the cooperation 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 explode and burn with delay.

[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] Anti-oxidation 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 heat 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 part 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 the 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 extension and burst performance of the cable; effectively avoiding the spark or arc leakage caused by the burst of the protective layer of the cable, 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 protection. Under high temperature conditions caused by overload and short circuit, halogen-free, low-smoke, flame-retardant cross-linked polyolefin can quickly form a carbonized layer, isolate the oxygen supply, delay 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, so that the insulation and protective materials of the cable can 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, and the insulation layer and the protective layer jointly form a thermal barrier, which gradually absorbs heat energy under high temperature conditions to avoid rapid temperature rise in a short period of time to cause burst or combustion. The protective layer can enhance the protection 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.

[0104] Based on the first embodiment of the cable that explodes and burns with 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 mixer to form a PA mixture;

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

[0107] S2.1: The drying temperature of the dryer is set to 90°C and the machine is heated for 5 minutes;

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

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

[0110] S4: The PA mixture of S2 is transferred into a screw extruder, and the mixed material of S3 is added, and the PA mixture and the mixed material are mixed and evenly extruded and pelletized to form mixed 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 blank 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 respectively, fusing them and wrapping them outside the conductor, and extruding and pulling out the finished cable wire;

[0114] S7.1: An axial air cooling device shall be installed 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 rolls the insulation pellets and the blended pellets in the first hopper and the second hopper into the melt in the heating channel respectively;

[0118] S7.5: Feed the conductor of S7.3 first, and pull out the wire 1-2m from the extrusion outlet to complete the pre-pulling 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, and 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 cable blank wire of the conductor in layers;

[0120] S7.6: Pull the cable blank wire of S7.5 out of the discharge port of the extruder to form a finished cable wire, pass it through the axial flow air cooling device of S7.1, and cool the finished cable wire to room temperature;

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

[0122] S9: Introduce the finished cable wire of S8 into the winding machine and reel it for packaging.

[0123] When applied, 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 implementation of the cable that bursts and burns with time delay in the 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 also includes a glass fiber reinforcement layer 5; the insulating layer 2 is divided into a first insulating layer 21 and a second insulating layer 22; the first insulating layer 21 is wrapped around the conductor 1, and the second insulating 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] When applied, the heat insulating property 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, and 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 of 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, it also includes silicon carbide reinforcement wires 6 ; the silicon carbide reinforcement wires 6 are spirally fused 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 delayed burst and delayed combustion cables made of silicon carbide reinforced wire 6 are generally only used in high-risk chemical field scenarios.

[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. The finished cable can avoid bursting in the overload protection layer 3 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 production method of a reinforced cable with delayed bursting and delayed 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 talcum powder coating machine are sequentially arranged in the direction from the conductor entering to the finished cable discharging;

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

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

[0136] S2.1: The drying temperature of the dryer is set to 90°C and the machine is heated for 5 minutes;

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

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

[0139] S4: The PA mixture of S2 is transferred into a screw extruder, and the mixed material of S3 is added, and the PA mixture and the mixed material are mixed and evenly extruded and pelletized to form mixed 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 a preheating device, and heating the conductor to 80-90° C. when the conductor passes through the preheating device;

[0142] S7: loading the insulating pellets into the hopper of the first extruder, melting the insulating pellets through the first extruder and wrapping them around the conductor of S6 to form a first insulating layer, and pulling out the first blank wire from the discharge port;

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

[0144] S8.1: passing the first blank wire of S7 through the first heat preservation device for heat preservation, and introducing it into the first weaving device, winding the first layer of spiral glass fiber on the first blank wire in a clockwise or counterclockwise direction, and pulling out the second blank wire;

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

[0146] S8.3: The third blank wire of S8.2 is introduced into the second heat preservation device and then introduced into the second weaving device, and the second layer of spiral glass fiber is wound on the third blank wire in the opposite winding direction to S8.1, and the fourth blank wire is pulled out;

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

[0148] S10: Introduce the fifth blank 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 outside the fifth blank wire to form a first layer of protective layer, and pull out the sixth blank wire from the discharge port;

[0149] S11: introducing the sixth blank wire of S10 into the third heat preservation device, and then introducing it into the third weaving device, spirally winding the silicon carbide reinforcing wire on the sixth blank wire in a clockwise or counterclockwise direction, and pulling out the seventh blank wire;

[0150] S12: Introduce the seventh blank 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 blank wire to form a second protective layer, and pull out the cable blank wire from the discharge port;

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

[0152] S14: passing the finished cable wire of S13 through a talcum powder coating machine, and coating the finished cable wire with talcum powder, so that the surface oxidation of the finished cable wire is slowed down and the surface wear is reduced;

[0153] S15: Introduce the finished cable wire of S14 into the winding machine and wrap it.

[0154] The finished cable line made by the composition, structure and production method of the first embodiment and the finished cable line made by the composition, structure and production method of the second embodiment were fed with a short-term high current exceeding 50-80% of the critical current of the finished cable line, and the experimental results were shown in the following table:

[0155]

[0156] From the above experimental results, it can be seen that the finished cable line of the first embodiment only has an insulating layer and a protective layer. When a current of 1.8 times the maximum critical current is passed through the finished cable line in the implementation, it can persist for at least 2 minutes without bursting or burning, even if the finished cable line is delayed for at least 2 minutes before bursting or burning. The finished cable line of the second embodiment, by adding a glass fiber reinforcement layer with heat insulation performance, a glass fiber reinforcement layer that increases the mechanical strength of the insulating layer, and a silicon carbide reinforcement line that increases the mechanical strength of the protective layer, does not burst under a short-term high current of 1.8 times the critical current, but also melts and fails. Compared with the first embodiment, the delayed failure time of the protective layer of the finished cable line is significantly enhanced, and the external oxygen is delayed from contacting the insulating layer, thereby increasing the delayed combustion time of the insulating layer to a greater extent.

[0157] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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, after the conductor is overloaded and short-circuited to cause high temperature, the cable will explode and burn with delay.

2. The cable capable of delayed explosion and combustion under overload and short circuit conditions according to claim 1 is characterized in that: The insulating layer is wrapped around the conductor, and the protective layer is wrapped around the insulating layer.

3. The cable capable of delayed explosion and combustion under overload and short circuit conditions according to claim 2 is characterized in that: Also includes fiberglass reinforcement; The insulating layer is divided into a first insulating layer and a second insulating layer; the first insulating layer is wrapped around the conductor, and the second insulating layer is wrapped around the glass fiber reinforcement layer.

4. The cable capable of delayed explosion and combustion under overload and short circuit conditions according to claim 3 is characterized in that: The glass fiber reinforcement layer comprises 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.

5. The cable capable of delayed explosion and combustion under overload and short circuit conditions according to claim 4, characterized in that: The clockwise spiral glass fiber layer has the same thickness as the counterclockwise spiral glass fiber layer; 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.

6. The cable capable of delayed explosion and combustion under overload and short circuit conditions according to any one of claims 4 or 5, characterized in that: The retaining layer is halogen-free, low-smoke, flame-retardant cross-linked polyolefin.

7. The cable capable of delayed explosion and combustion under overload and short circuit conditions according to claim 6, characterized in that: It also includes a silicon carbide reinforcement wire; the silicon carbide reinforcement wire is spirally fused into the protective layer.

8. A method for producing a cable capable of delayed bursting and burning under overload and short circuit conditions according to claim 2, characterized in that: The following steps are involved: S1: PA11 and PA66 are fully mixed in a mixer to form a PA mixture; S2: Transfer the PA mixture into a dryer for drying; S2.1: The drying temperature of the dryer is set to 90°C and the machine is heated for 5 minutes; S2.2: Place the PA mixture in the dryer and bake for 4 minutes; S3: mixing the antioxidant and the anti-hydrolysis agent evenly to form a mixed material; S4: The PA mixture of S2 is transferred into a screw extruder, and the mixed material of S3 is added, and the PA mixture and the mixed material are mixed and evenly extruded and pelletized to form mixed 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 blank 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 respectively, fusing them and wrapping them outside the conductor, and extruding and pulling out the finished cable wire; S7.1: An axial air cooling device shall be installed at least 1 m from the extrusion outlet of the extruder; 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; S7.3: Introduce the conductor in S6 into the cable inlet of the extruder; S7.4: The extruder rolls the insulation pellets and the blended pellets in the first hopper and the second hopper into the melt in the heating channel respectively; S7.5: Feed the conductor of S7.3 first, and pull out the wire 1-2m from the extrusion outlet to complete the pre-pulling 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, and 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 cable blank wire of the conductor in layers; S7.6: Pull the cable blank wire of S7.5 out of the discharge port of the extruder to form a finished cable wire, pass it through the axial flow air cooling device of S7.1, and cool the finished cable wire to room temperature; S8: Apply talcum powder on the surface of the finished cable line of S7 to prevent surface oxidation and reduce surface wear; S9: Introduce the finished cable wire of S8 into the winding machine and wrap it.

9. A method for producing a cable capable of delayed bursting and burning under overload and short circuit conditions according to claim 7, 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 talcum powder coating machine are sequentially arranged; The following steps are involved: S1: PA11 and PA66 are fully mixed in a mixer to form a PA mixture; S2: Transfer the PA mixture into a dryer for drying; S2.1: The drying temperature of the dryer is set to 90°C and the machine is heated for 5 minutes; S2.2: Place the PA mixture in the dryer and bake for 4 minutes; S3: mixing the antioxidant and the anti-hydrolysis agent evenly to form a mixed material; S4: The PA mixture of S2 is transferred into a screw extruder, and the mixed material of S3 is added, and the PA mixture and the mixed material are mixed and evenly extruded and pelletized to form mixed 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 a preheating device, and heating the conductor to 80-90°C when the conductor passes through the preheating device; S7: loading the insulating pellets into the hopper of the first extruder, melting the insulating pellets through the first extruder and wrapping them around the conductor of S6 to form a first insulating layer, and pulling out the first blank wire from the discharge port; S8: Insulation and winding with glass fiber reinforcement layer; S8.1: passing the first blank wire of S7 through the first heat preservation device for heat preservation, and introducing it into the first weaving device, winding the first layer of spiral glass fiber on the first blank wire in a clockwise or counterclockwise direction, and pulling out the second blank wire; S8.2: Introduce the second blank wire of S8.1 into the cable inlet of the second extruder, load the insulating pellets into the hopper of the second extruder, melt the insulating pellets and wrap them around the second blank wire to form a retaining layer, and pull out the third blank wire from the discharge port; S8.3: The third blank wire of S8.2 is introduced into the second heat preservation device and then introduced into the second weaving device, and the second layer of spiral glass fiber is wound on the third blank wire in the opposite winding direction to S8.1, and the fourth blank wire is pulled out; S9: Introduce the fourth blank wire of S8.3 into the cable inlet of the third extruder, load the insulating pellets into the hopper of the third extruder, melt the insulating pellets and wrap them around the second blank wire to form a second insulating layer, and pull out the fifth blank wire from the discharge port; S10: Introduce the fifth blank 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 blank wire to form a first layer of protective layer, and pull out the sixth blank wire from the discharge port; S11: introducing the sixth blank wire of S10 into the third heat preservation device, and then introducing it into the third weaving device, spirally winding the silicon carbide reinforcing wire on the sixth blank wire in a clockwise or counterclockwise direction, and pulling out the seventh blank wire; S12: Introduce the seventh blank 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 blank wire to form a second protective layer, and pull out the cable blank wire from the discharge port; S13: passing the cable blank wire of S12 through an axial flow air cooling device to cool the cable blank wire to obtain a finished cable wire; S14: passing the finished cable wire of S13 through a talcum powder coating machine, and coating the finished cable wire with talcum powder, so that the surface oxidation of the finished cable wire is slowed down and the surface wear is reduced; S15: Introduce the finished cable wire of S14 into the winding machine and wrap it.

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