Manufacturing method of direct current fuse

Abstract

According to the manufacturing method of the direct-current fuse, provided by the invention, a plurality of functional aids such as polyether-ether-ketone (PEEK), polybutylene terephthalate (PBT), boron nitride micro powder, mica powder, antimony trioxide, graphene nanosheets and flexible polyester fibers are introduced into an insulating shell material, so that the heat conductivity, dielectric strength and thermal shock resistance of the insulating shell are remarkably improved; the problem of shell bulging or bursting caused by instantaneous high temperature in the arc fusing process can be effectively avoided, and long-term stable operation of the fuse is ensured; the end cap is formed by punching a T2 red copper material and is subjected to silver plating treatment, and is matched with an elastic arc-shaped plugging metal sheet structure, so that the conductivity and the oxidation resistance are improved, and the electrical contact reliability between the fusible core and the end cap is also enhanced; meanwhile, by arranging an expansion sealing structure formed by the double annular grooves and the annular rubber rings, the produced direct-current fuse can be detachably connected, the end caps are effectively prevented from loosening, and the vibration resistance and the air tightness of the whole machine are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuses, and in particular to a method for manufacturing a DC fuse. Background Art

[0002] A fuse is an electrical protection device that automatically disconnects the circuit by melting its fuse element when the current exceeds a specified value. Its operating principle is that when the current exceeds the set value and persists for a certain period of time, the current flowing through the fuse element raises its temperature to its melting point, causing it to melt and interrupt the current flow, thereby protecting the circuit and equipment. Fuses offer advantages such as simple structure, rapid response, and reliable protection. Therefore, they are widely used in high and low voltage power distribution systems, control systems, and various electrical equipment. They are currently one of the most common and fundamental short-circuit and overload protection devices.

[0003] Existing DC fuses usually include basic components such as end caps, fuse cores, and insulating casings. The fuse core is used to achieve the power-off function in the event of overcurrent, the end caps are used to connect to the external circuit, and the insulating casing is responsible for electrical insulation, mechanical protection, and thermal isolation. Currently, commonly used insulating materials are mostly engineering plastics such as polybutylene terephthalate (PBT), polycarbonate (PC), or nylon (PA). However, these materials often face risks such as melting, thermal deformation, and even bursting in high-temperature and high-voltage DC working environments, making it difficult to meet the needs of long-term stable operation. Especially at the moment of melting, due to the concentrated release of arc heat, if the thermal conductivity of the insulating casing is insufficient, heat accumulation can easily form in local areas, causing carbonization of the material or rupture of the casing, which in turn causes secondary failures.

[0004] Furthermore, existing fuses typically utilize a one-piece sealed structure, with the internal fusible core (also known as the fuse element) non-removably enclosed in an insulating housing. When the fuse element blows due to a fault current, the entire fuse must be replaced, increasing maintenance costs. Furthermore, the damaged fuse housing is often made of non-recyclable materials, such as thermosetting plastics, which can pollute the environment and make it difficult to meet current green and sustainable development requirements. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a method for manufacturing a DC fuse, which solves the problems of poor thermal stability of the insulating shell, insufficient thermal conductivity, limited structural sealing, and high replacement and maintenance costs of DC fuses.

[0006] A method for manufacturing a DC fuse, which is used to manufacture a DC fuse, wherein the DC fuse includes a pair of end caps, a fusible core, and an insulating shell, wherein the end caps are buckled and arranged at both ends of the insulating shell, a positioning groove is provided on the side of the end cap close to the insulating shell, a pair of opposite arc-shaped plug-in metal sheets are provided in the middle of the end cap, the inner side of the side wall of the end cap is recessed toward the outer side and is provided with at least one annular groove, the side edge of the insulating shell is provided with an insulating positioning column adapted to the positioning groove, a limiting structure for a limited fusible core is provided in the insulating shell, the outer side walls of the two ends of the insulating shell are recessed inwardly with annular fixing grooves, and the annular fixing groove is sleeved with a groove that matches the annular groove. The invention relates to a ring-shaped rubber ring for expansion connection, wherein the manufacturing method of the DC fuse comprises the following steps: (1) preparing a raw material mixture of an insulating shell, wherein the mixture is configured as follows in terms of mass percentage: polyetheretherketone (PEEK) 20-30%, polybutylene terephthalate (PBT) 15-25%, boron nitride powder (BN) 10-20%, mica powder 5-10%, antimony trioxide 3-6%, silane coupling agent 0.5-1%, polytetrafluoroethylene powder 1-3%, coated graphene nanosheets 0.1-0.5%, flexible polyester fiber chopped strands 0.5-1%, antioxidant and ultraviolet absorber 0.1-0.3% each; (2) preparing the raw material mixture of the insulating shell, wherein the raw material mixture of the insulating shell is configured as follows in terms of mass percentage: polyetheretherketone (PEEK) 20-30%, polybutylene terephthalate (PBT) 15-25%, boron nitride powder (BN) 10-20%, mica powder 5-10%, enhancing insulation and dielectric strength, antimony trioxide 3-6%, silane coupling agent 0.5-1%, polytetrafluoroethylene powder 1-3%, coated graphene nanosheets 0.1-0.5%, flexible polyester fiber chopped strands 0.5-1%, antioxidant and ultraviolet absorber 0.1-0.3% each; (3) preparing the raw material mixture of the insulating shell, wherein the raw material mixture of the insulating shell is configured as follows: polyetheretherketone (PEEK) 20-30%, polybutylene terephthalate (PBT) 15-25%, boron nitride powder (BN) 10-20%, mica powder 5-10%, enhancing insulation and dielectric strength, antimony trioxide 3-6%, silane coupling agent 0.5-1%, polytetrafluoroethylene powder 1-3%, coated graphene nano The mixture is granulated in a twin-screw extruder, the extrusion temperature is controlled at 250-290°C, and the shear rate is controlled at 150rpm to obtain a granular material for injection molding of an insulating shell; (3) the insulating shell is prepared by injection molding process, the mold temperature is controlled at 80-100°C, the holding pressure is 70-90MPa, the time is 6-12 seconds, and the mold is cooled and demoulded to form an insulating shell, the positioning column, the limiting structure, and the annular fixing grooves at both ends are integrally formed inside the insulating shell, and an annular rubber ring is set on the annular fixing groove after molding; (4) the end cap is manufactured, the end cap is stamped and formed by T2 copper material, and the surface is coated with a silver layer with a thickness of 1-3μm to improve the conductive performance and anti-oxidation Performance; (5) A pair of arc-shaped plug-in metal sheets are fixed in the middle of the end cap, and the arc-shaped plug-in metal sheets are made of elastic copper alloy material. They are first hot-bent into a structure including a first arc segment, a straight segment and a second arc segment, and then the first arc segment is welded to the inner side of the end cap by welding; (6) A fusible core is manufactured, which is a hollow glass fiber tube or an alumina ceramic tube, and a low-melting-point silver-copper alloy wire is passed through the inside thereof, and metal contacts are welded at both ends, and the metal contacts are silver-plated copper sheets; (7) One end of the insulating shell is connected to the end cap, and then the fusible core is inserted into the through hole in the middle of the insulating shell, and the metal contact at one end of the fusible core is inserted between the plug-in metal sheets between the installed end caps, and then the end cap on the other side is tightened.

[0007] Preferably, the arc-shaped plug-in metal sheet includes a first arc segment, a straight segment connected to the first arc segment, and a second arc segment connected to the other end of the straight segment. The first arc segments of the two arc-shaped plug-in metal sheets are welded on the end caps, the straight segments of the two arc-shaped plug-in metal sheets are abutted, and the second arc segments of the two arc-shaped plug-in metal sheets are relatively arranged with a gap.

[0008] Preferably, the limiting structure comprises a plurality of groups of relatively arranged arc-shaped fixing members arranged inside the insulating shell, wherein two of the arc-shaped fixing members are arranged in a group and are located on the same horizontal plane.

[0009] Preferably, a plurality of telescopic springs are evenly connected between a side of the arc-shaped fixing member away from the other arc-shaped fixing member and an inner side wall of the insulating shell.

[0010] Preferably, the number of the annular groove and the number of the annular rubber ring are both set to 2.

[0011] Preferably, the maximum diameters of the two outermost annular rubber rings of the insulating shell are smaller than the maximum diameters of the two innermost annular rubber rings of the insulating shell.

[0012] Preferably, in the injection molding process of step (3), an ultrasonic vibration-assisted molding step is added, an ultrasonic transducer is provided on the outside of the molding mold, and ultrasonic waves with a frequency of 20 to 40 kHz and an amplitude of 5 to 15 μm are applied during the injection cooling stage.

[0013] Preferably, a fluorosilicone coating is coated on the outer surface of the annular rubber ring, and the thickness of the fluorosilicone coating is 10 to 50 μm.

[0014] Preferably, the inner surface of the insulating shell is further provided with a ceramic coating layer, the thickness of the ceramic coating layer is 50-100 μm, and the material is aluminum silicate ceramic slurry coating and sintering at 850° C.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention provides a method for manufacturing a DC fuse. By introducing multiple functional additives such as polyetheretherketone (PEEK), polybutylene terephthalate (PBT), boron nitride powder, mica powder, antimony trioxide, graphene nanosheets and flexible polyester fiber into the insulating shell material, the thermal conductivity, dielectric strength and thermal shock resistance of the insulating shell are significantly improved, which can effectively avoid the problem of shell bulging or bursting due to instantaneous high temperature during arc fusing, and ensure the long-term stable operation of the fuse; the end cap is stamped and formed of T2 copper material and silver-plated, and is combined with an elastic arc-shaped plug-in metal sheet structure, which not only improves the conduction The electrical properties and anti-oxidation ability are improved, and the electrical contact reliability between the fuse core and the end cap is enhanced; at the same time, the expansion sealing structure realized by arranging double annular grooves and annular rubber rings can realize the detachable connection of the produced DC fuse, and effectively prevent the end cap from loosening, and improve the vibration resistance and air tightness of the whole machine; therefore, the manufacturing method of the DC fuse adopts standardized injection molding, extrusion, stamping, welding and other processes, which is suitable for mass production and has good product consistency; at the same time, the use of recyclable thermoplastic materials and the production of the fuse is detachable and designed to facilitate later maintenance and recycling, which is in line with the trend of green environmental protection and energy conservation and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the cross-sectional structure of the DC fuse according to the present invention;

[0018] Figure 2 This is a schematic top view of the insulating housing of the present invention;

[0019] in:

[0020] 10-end cap, 20-fuse core, 30-insulating shell, 40-arc-shaped plug-in metal sheet, 50-annular groove, 60-annular fixing groove, 70-annular rubber ring, 80-arc-shaped fixing piece, 21-metal contact, 41-first arc-shaped segment, 42-straight segment, 43-second arc-shaped segment. DETAILED DESCRIPTION

[0021] The embodiments described below are only some of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] See Figure 1 as well as Figure 2, this embodiment provides a method for manufacturing a DC fuse, which is used to manufacture a DC fuse, the DC fuse comprising a pair of end caps 10, a fuse core 20, and an insulating shell 30, the end caps 10 are snap-fitted onto the two ends of the insulating shell 30, a positioning groove is provided on the side of the end cap 10 close to the insulating shell 30, a pair of opposite arc-shaped plug-in metal sheets 40 are provided in the middle of the end cap 10, the inner side of the side wall of the end cap 10 is recessed toward the outer side to form at least one annular groove 50, the side edge of the insulating shell 30 is provided with an insulating positioning column adapted to the positioning groove, a limiting structure for limiting the fuse core 20 is provided in the insulating shell 30, the outer side walls of the two ends of the insulating shell 30 are recessed inwardly with annular fixing grooves 60, and an annular rubber ring 70 is sleeved on the annular fixing groove 60 and is tightly connected to the annular groove 50.

[0023] It should be noted that when the internal fuse 20 needs to be replaced, the end cap 10 on one side is removed, and then the broken fuse 20 is taken out, and then the new fuse 20 is inserted. One end of the fuse 20 is inserted between the arc-shaped plug-in metal sheet 40 of the other end cap 10 that has not been unscrewed or has been unscrewed and cleaned and continues to be plugged into one end of the insulating shell 30. At the same time, the fuse 20 is restricted by the limiting structure, which also facilitates the insertion of the other end of the fuse 20 between the arc-shaped plug-in metal sheet 40 of the other end cap 10, and then the end cap 10 is inserted through the other end of the insulating shell 30. At this time, the positioning groove and the insulating positioning column cooperate to achieve rapid positioning and stable connection of the end cap 10, and then the end cover continues to be pressed down for installation. The annular rubber ring 70 provided on the insulating shell 30 is tightened to the annular groove 50 of the annular groove 50 provided on the side wall of the end cap 10, thereby forming a tightly fitting sealing connection structure, which effectively prevents external impurities such as dust and water vapor from invading the interior of the fuse, thereby improving its overall protection performance and environmental adaptability. After installation is completed, the fuse core 20 is securely positioned by the limiting structure to avoid displacement or loosening during use, thereby ensuring stable and reliable electrical connection.

[0024] Specifically, the manufacturing method of the DC fuse includes the following steps: (1) preparing a raw material mixture of the insulating shell 30, wherein the mixture is configured as follows in mass percentage: polyetheretherketone (PEEK) 20-30%, polybutylene terephthalate (PBT) 15-25%, boron nitride powder (BN) 10-20%, mica powder 5-10%, antimony trioxide 3-6%, silane coupling agent 0.5-1%, polytetrafluoroethylene powder 1-3%, coated graphene nanosheets 0.1-0.5%, flexible polyester fiber chopped strands 0.5-1%, antioxidant and ultraviolet absorber 0.1-0.3% each; in this embodiment, polyetheretherketone (PEEK) and polybutylene terephthalate (PBT) are used as the main matrix resins, taking into account the structural strength and processing fluidity at high temperature, ensuring that the shell can maintain dimensional stability both during the injection molding process and in service; boron nitride (BN) The synergistic filling of BN) micropowder and mica powder significantly improves the thermal conductivity and dielectric strength of the material, effectively suppressing the risk of carbonization, breakdown or explosion of the material caused by local temperature rise; antimony trioxide provides good flame retardancy, inhibiting the spread of combustion during arc impact; silane coupling agent enhances the bonding strength between the inorganic filler and the resin interface, ensuring uniform distribution and structural stability of the mixture; polytetrafluoroethylene micropowder gives the material excellent arc resistance and self-lubrication, enhancing its surface insulation and anti-fouling capabilities; graphene nanosheets provide significant thermal conductivity reinforcement and crack blocking effects at extremely low addition levels, while also possessing certain electromagnetic shielding capabilities; flexible polyester fiber chopped strands serve as a reinforcing phase to improve the toughness and impact resistance of the composite material, preventing structural rupture caused by external force impact; the synergistic use of antioxidants and UV absorbers can delay the thermal oxidation degradation and photoaging process of the polymer chain, improving the long-term reliability of the product in complex outdoor or high-humidity and heat environments. The synergistic effect of all the above ingredients gives the resulting composite material excellent mechanical strength, dimensional stability, thermal conductivity, electrical insulation, flame retardancy and weather resistance. These properties meet the requirements of high-voltage DC fuses for shell materials under harsh operating conditions such as high voltage, high current, and high-frequency fusing, providing a solid guarantee for the safety and life of the fuse.

[0025] (2) The prepared mixture is granulated in a twin-screw extruder, the extrusion temperature is controlled at 250-290°C, and the shear rate is controlled at 150rpm to obtain a granular material for injection molding of the insulating shell 30; the mixture is efficiently mixed and granulated by a twin-screw extruder, the extrusion temperature is controlled in the range of 250-290°C and the shear rate is maintained at 150rpm, so that each component is fully melted and evenly dispersed, while avoiding thermal degradation and adhesion. The obtained injection molding particles have stable particle size and are evenly dispersed, ensuring good material fluidity and filling properties in the subsequent injection molding process, thereby improving the consistency and mechanical strength of the insulating shell.

[0026] (3) The insulating shell 30 is prepared by injection molding process, the mold temperature is controlled at 80-100°C, the holding pressure is 70-90 MPa, the time is 6-12 seconds, and the mold is cooled and demolded to form an insulating shell, which has the positioning column, the limiting structure, and the annular fixing grooves 60 at both ends integrally formed inside. After molding, an annular rubber ring 70 is sleeved on the annular fixing groove 60; the insulating shell prepared by injection molding process is not only accurate in size and high in molding efficiency, but also realizes the integral molding of the positioning column, the limiting structure and the annular fixing groove 60, significantly reducing the accumulation of assembly tolerances and manual errors, and improving the assembly accuracy and mechanical stability of the overall structure; controlling key parameters such as mold temperature, holding pressure and cooling time helps to avoid internal stress and shrinkage deformation, so that the insulating shell has excellent dimensional stability and heat resistance; after molding, the annular rubber ring 70 is sleeved on the annular fixing groove 60 to improve the sealing and seismic resistance of the shell and the end cap 10.

[0027] (4) The end cap 10 is made of T2 copper material with high conductivity. The structural consistency and precision are ensured by a stamping process. At the same time, a silver layer with a thickness of 1 to 3 μm is uniformly electroplated on its surface, which significantly improves its corrosion resistance, conductivity and contact stability, helps to maintain reliable electrical performance under high voltage and high current impact conditions, and extends the overall service life of the fuse.

[0028] (5) A pair of arc-shaped plug-in metal sheets 40 are fixed in the middle of the end cap 10. The arc-shaped plug-in metal sheets 40 are made of elastic copper alloy material. They are first hot-bent into a structure comprising a first arc segment 41, a straight segment 42 and a second arc segment 43, and then the first arc segment 41 is welded to the inner side of the end cap 10 by welding. The arc-shaped plug-in metal sheets 40 are made of elastic copper alloy and are pre-bent to form a structure comprising a first arc segment 41, a straight segment 42 and a second arc segment 43, so that they have excellent elasticity and fatigue resistance. This structure can form a stable and elastic contact fit after the fuse 20 is inserted, thereby achieving reliable electrical connection and conduction between the fuse 20 and the end cap 10 during use, avoiding heating or even breakdown problems caused by poor contact.

[0029] (6) Manufacturing the fuse core 20, which uses a hollow glass fiber tube or an alumina ceramic tube as a base, and a low-melting-point silver-copper alloy wire is passed through the inside to ensure that it can quickly fuse under overcurrent conditions; the silver-plated copper contacts set at both ends further enhance the electrical connection performance and anti-oxidation life, making the fuse core 20 sensitive to action and reliable in melting, and having excellent overload protection effect in various DC systems.

[0030] (7) One end of the insulating housing 30 is connected to the end cap 10. Then, the fuse core 20 is inserted into the through hole in the middle of the insulating housing 30. The metal contact 21 at one end of the fuse core 20 is inserted between the plug-in metal sheets between the installed end caps 10. Then, the end cap 10 on the other side is tightened. The entire installation and assembly process is simple in structure, highly efficient, and does not rely on welding technology, making it easy to repair and replace. At the same time, the assembled fuse has strong airtightness and high mechanical strength, making it suitable for stable operation of high-voltage DC systems.

[0031] Preferably, the arcuate plug-in metal sheet 40 includes a first arcuate segment 41, a straight segment 42 connected to the first arcuate segment 41, and a second arcuate segment 43 connected to the other end of the straight segment 42. The first arcuate segments 41 of the two arcuate plug-in metal sheets 40 are welded to the end cap 10, and the straight segments 42 of the two arcuate plug-in metal sheets 40 abut against each other. The second arcuate segments 43 of the two arcuate plug-in metal sheets 40 are arranged opposite each other with a gap therebetween. During assembly, the metal contacts 21 at both ends of the fuse 20 are first inserted through the gap between the second arcuate segments 43. During insertion, the arcuate segments have a limited elastic expansion capability. As the metal contacts 21 continue to be inserted and contact the straight segment 42, they are compressed and clamped between the two straight segments 42 under appropriate pressure, thereby achieving a stable electrical connection with high conductivity. Therefore, the arc-shaped plug-in metal sheet 40 not only enables the metal contact 21 to be quickly inserted and removed, but also effectively prevents the connection from loosening or falling off due to factors such as vibration, thermal expansion and contraction through the clamping effect of the straight section 42, further improving the reliability and structural stability of the connection. In addition, since the metal contact 21 and the plug-in metal sheet are elastically connected, it is also convenient for the replacement and maintenance of the fuse core 20 in the future, improving the maintainability and service life of the entire device. It should be noted that in an emergency situation, if the fuse core 20 cannot be found, a small copper wire can be used as the fuse core 20 for emergency use. When using copper wire, the copper wire needs to be set longer so that the end of the copper wire is clamped between the plug-in metal sheets or can be wrapped around the arc-shaped plug-in metal sheet 40. The longer setting is because the copper wire needs to be inserted into the insulating shell 30 first, and then the two ends of the copper wire are connected to the arc-shaped plug-in metal sheet 40, and then the end cap 10 is inserted into the insulating shell 30.

[0032] Preferably, the retaining structure includes multiple sets of oppositely positioned arc-shaped fixing members 80 disposed within the insulating housing 30, wherein two of the arc-shaped fixing members 80 are arranged in a group and located on the same horizontal plane. The two arc-shaped fixing members 80 are symmetrically distributed on either side of the fusible core 20 in the radial direction. Their curvatures match the outer surface contour of the fusible core 20, forming a partially enclosing clamping structure. This provides a stable retaining effect on the fusible core 20 without affecting the insertion and removal operations of the fusible core 20.

[0033] Preferably, multiple telescopic springs are evenly connected between the side of the arc-shaped fixing member 80 facing away from the other arc-shaped fixing member 80 and the inner sidewall of the insulating housing 30. These telescopic springs impart a certain elastic tension to the arc-shaped fixing member 80, allowing it to properly yield when inserting the fusible core 20. Once installed, they also provide a clamping and securing effect on the fusible core 20, preventing it from shaking, becoming loose, or axially slipping during transportation, vibration, or use. Of course, the arc-shaped fixing member 80 can also be fixedly connected to the insulating housing 30, but this will not be discussed further here.

[0034] Preferably, the number of the annular groove 50 and the annular rubber ring 70 is set to 2. The maximum diameter of the two outermost annular rubber rings 70 of the insulating shell 30 is smaller than the maximum diameter of the two inner annular rubber rings 70 of the insulating shell 30. When the end cap 10 is inserted into the insulating shell 30, the annular rubber ring 70 with a larger outer diameter forms a tight crimping fit with the annular groove 50 on the side wall of the end cap 10 to achieve a tight connection; while the smaller diameter rubber ring on the inner side is embedded in the corresponding groove to provide secondary sealing and anti-escape ability, thereby achieving step-by-step locking and multiple sealing as a whole, and improving the tightness and stability of the connection part. It should be noted that the diameter of the two outermost annular rubber rings 70 is smaller, so that the large annular fixing groove 60 on the end cap can first pass through this annular rubber ring 70 and then connect with the large annular rubber ring 70 on the inner side.

[0035] Preferably, in the injection molding process described in step (3), an ultrasonic vibration-assisted molding step is added, an ultrasonic transducer is provided on the outside of the molding mold, and ultrasonic waves with a frequency of 20 to 40 kHz and an amplitude of 5 to 15 μm are applied during the injection molding cooling stage. The high-frequency vibration effect of ultrasonic waves can break the entanglement of molecular chains during the filling and cooling of the molten material, promote the orderly arrangement and directional crystallization of polymer segments, and thus improve the density and crystallinity of the material. At the same time, ultrasonic vibration can effectively reduce the adhesion between the mold and the material, reduce the demoulding resistance, and improve the product dimensional accuracy and surface finish. In addition, the perturbation introduced by the vibration helps the bubble escape and filling uniformly, significantly reduces the probability of internal defects, improves the overall mechanical properties and insulation consistency of the product, and makes the formed insulating shell have better structural strength, dielectric properties and long-life operation stability in a high-voltage direct current environment.

[0036] Preferably, the outer surface of the annular rubber ring 70 is coated with a fluorosilicone coating having a thickness of 10 to 50 μm. This coating can significantly improve the wear and corrosion resistance of the rubber ring, enhance its surface hydrophobicity and anti-adhesion properties, thereby extending the service life of the rubber ring, improving its overall sealing performance and reliability, and adapting it to more severe operating environments.

[0037] Preferably, the inner surface of the insulating shell 30 is also provided with a ceramic coating layer. The thickness of the ceramic coating layer is 50 to 100 μm. The material is aluminum silicate ceramic slurry coated and sintered at 850°C, which can significantly improve the arc resistance and thermal shock resistance inside the fuse.

[0038] The present invention provides a method for manufacturing a DC fuse. By introducing multiple functional additives such as polyetheretherketone (PEEK), polybutylene terephthalate (PBT), boron nitride powder, mica powder, antimony trioxide, graphene nanosheets and flexible polyester fiber into the material of the insulating shell 30, the thermal conductivity, dielectric strength and thermal shock resistance of the insulating shell are significantly improved, which can effectively avoid the problem of shell bulging or bursting due to instantaneous high temperature during arc fusing, ensuring the long-term stable operation of the fuse; the end cap 10 is stamped and silver-plated with T2 copper material, and is combined with the elastic arc-shaped plug-in metal sheet 40 structure, which not only improves the conductivity Energy and anti-oxidation capabilities, and also enhances the electrical contact reliability between the fuse core 20 and the end cap 10; at the same time, the expansion sealing structure achieved by arranging the double annular groove 50 and the annular rubber ring 70 can realize the produced DC fuse with detachable connection, and also effectively prevent the end cap 10 from loosening, and improve the vibration resistance and air tightness of the whole machine; therefore, the manufacturing method of the DC fuse adopts standardized injection molding, extrusion, stamping, welding and other processes, which is suitable for mass production and has good product consistency; at the same time, the use of recyclable thermoplastic materials and the production of the fuse with a detachable design are convenient for later maintenance and recycling, which is in line with the trend of green environmental protection and energy conservation and sustainable development.

[0039] The above disclosures are merely some preferred embodiments of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention are still within the scope covered by the present invention.

Claims

1. A method for manufacturing a DC fuse, which is used to manufacture a DC fuse, the DC fuse comprising a pair of end caps, a fusible core, and an insulating shell, the end caps being snap-fitted to both ends of the insulating shell, a positioning groove being provided on a side of the end cap close to the insulating shell, a pair of opposing arc-shaped plug-in metal sheets being provided in the middle of the end cap, at least one annular groove being recessed toward the outer side of the inner side of the side wall of the end cap, an insulating positioning column being provided on the side edge inside the insulating shell to match the positioning groove, a limiting structure for limiting the fusible core being provided inside the insulating shell, an annular fixing groove being recessed inwardly on the outer side walls at both ends of the insulating shell, an annular rubber ring being sleeved on the annular fixing groove to be tightly connected to the annular groove, characterized in that: The manufacturing method of the DC fuse comprises the following steps: (1) preparing a raw material mixture for an insulating shell, wherein the mixture is configured as follows by mass percentage: 20-30% polyetheretherketone, 15-25% polybutylene terephthalate, 10-20% boron nitride powder, 5-10% mica powder, 3-6% antimony trioxide for enhancing insulation and dielectric strength, 0.5-1% silane coupling agent, 1-3% polytetrafluoroethylene powder, 0.1-0.5% coated graphene nanosheets, 0.5-1% flexible polyester fiber chopped strands, and 0.1-0.3% each of an antioxidant and a UV absorber; (2) granulating the prepared mixture in a twin-screw extruder, controlling the extrusion temperature at 250-290° C. and the shear rate at 150 rpm, to obtain a granular material for injection molding of an insulating shell; (3) The insulating shell is prepared by injection molding, the mold temperature is controlled at 80-100°C, the holding pressure is 70-90 MPa, the time is 6-12 seconds, and the mold is cooled and demolded to form an insulating shell, which has the positioning column, the limiting structure, and the annular fixing grooves at both ends integrally formed therein. After molding, an annular rubber ring is placed on the annular fixing groove; (4) manufacturing the end cap, wherein the end cap is stamped and formed from T2 copper material, and the surface is plated with a silver layer with a thickness of 1 to 3 μm to improve the electrical conductivity and anti-oxidation performance; (5) A pair of arc-shaped plug-in metal sheets are fixed in the middle of the end cap. The arc-shaped plug-in metal sheets are made of elastic copper alloy material. The arc-shaped plug-in metal sheets are first hot-bent into a structure including a first arc segment, a straight segment, and a second arc segment. The first arc segment is then welded to the inner side of the end cap; (6) Manufacturing a fusible core, which is a hollow glass fiber tube or alumina ceramic tube, with a low melting point silver-copper alloy wire inserted inside and metal contacts welded at both ends, the metal contacts being silver-plated copper sheets; (7) Connect one end of the insulating shell to the end cap, then insert the fuse into the through hole in the middle of the insulating shell, insert the metal contact at one end of the fuse into the plug-in metal sheets between the installed end caps, and then tighten the end cap on the other side.

2. The method for manufacturing a DC fuse according to claim 1, wherein: The arc-shaped plug-in metal sheet includes a first arc segment, a straight segment connected to the first arc segment, and a second arc segment connected to the other end of the straight segment. The first arc segments of the two arc-shaped plug-in metal sheets are welded on the end caps, the straight segments of the two arc-shaped plug-in metal sheets are abutted, and the second arc segments of the two arc-shaped plug-in metal sheets are relatively arranged with a gap.

3. The method for manufacturing a DC fuse according to claim 2, wherein: The limiting structure includes a plurality of groups of relatively arranged arc-shaped fixing members arranged inside the insulating shell, wherein two of the arc-shaped fixing members are arranged in a group and are located on the same horizontal plane.

4. The method for manufacturing a DC fuse according to claim 3, wherein: A plurality of telescopic springs are evenly connected between one side of the arc-shaped fixing piece away from the other arc-shaped fixing piece and the inner side wall of the insulating shell.

5. The method for manufacturing a DC fuse according to claim 1, wherein: The number of the annular groove and the number of the annular rubber ring are both set to 2.

6. The method for manufacturing a DC fuse according to claim 1, wherein: The maximum diameter of the two outermost annular rubber rings of the insulating shell is smaller than the maximum diameter of the two inner annular rubber rings of the insulating shell.

7. The method for manufacturing a DC fuse according to claim 1, wherein: In the injection molding process of step (3), an ultrasonic vibration-assisted molding step is added, and an ultrasonic transducer is provided on the outside of the molding mold to apply ultrasonic waves with a frequency of 20 to 40 kHz and an amplitude of 5 to 15 μm during the injection cooling stage.

8. The method for manufacturing a DC fuse according to claim 1, wherein: A layer of fluorosilicone coating is coated on the outer surface of the annular rubber ring, and the thickness of the fluorosilicone coating is 10 to 50 μm.

9. The method for manufacturing a DC fuse according to claim 1, wherein: The inner surface of the insulating shell is further provided with a ceramic coating layer. The thickness of the ceramic coating layer is 50-100 μm and the material is aluminum silicate ceramic slurry coating and sintering at 850° C.

Images