A method of manufacturing a multi-layered lateral composite strip for a fuse

Abstract

The application provides a preparation method of a multilayer lateral composite strip for a fuse, and specifically comprises the following steps: vacuum smelting and pouring oxygen-free copper into a plate with N square grooves, then putting silver blocks into the square grooves, heating under a protective gas, and then hot pressing by an extruder; then heating under a protective gas, opening and breaking by concave-convex rollers, milling off the upper and lower surfaces, and finishing rolling to a finished product. The square groove structure can accurately position the silver layer, save noble metals to the maximum extent, and ensure that the circuit protection equipment is cut off when an abnormal current appears in the circuit; through the concave-convex roller rolling composite, the problem of cracks generated between the silver and copper interfaces and the poor lateral bonding strength can be effectively solved, so that the bonding strength is firm and reliable, the lateral composite strength is high, and the yield is high. Moreover, the strip manufactured by the method has stable performance and can be mass-produced.

Description

A method for preparing multilayer lateral composite strip for fuses Technical Field

[0001] This invention belongs to the technical field of composite materials, and specifically relates to a method for preparing a multilayer lateral composite strip for fuses. Background Technology

[0002] A fuse is an electrical device that uses a metal conductor as a fusible element to break a circuit. When the current in the protected circuit exceeds a specified value, and after a certain period of time, the heat generated by the fusible element melts it, thus protecting the power system, various electrical equipment, and household appliances. Fuses are widely used in low-voltage power distribution systems, control systems, and electrical equipment as short-circuit and overcurrent protection devices, and are one of the most commonly used protective devices. During a short circuit, the current in the circuit is at its maximum, undoubtedly far exceeding the rated current of the equipment. If the circuit is not broken in time, the electrical equipment will quickly burn out due to the large current. Therefore, to promptly cut off the circuit and protect equipment from damage, a fuse is used. Its principle is that when a large current is generated in the circuit, the fuse wire quickly melts before the equipment is damaged, thus achieving the purpose of cutting off the circuit. Cu / Ag multilayer strip uses side-composite technology to replace traditional pure silver products, using Cu in non-functional positions to save precious metal usage. When the current is overloaded, the Ag at the melt location melts quickly, providing timely and effective protection.

[0003] The manufacturing technology for through-hole composite silver-copper strips is complex, and relevant research institutes and enterprises both domestically and internationally possess their own unique technologies. Melt-bonded strips prepared using existing methods involve complex processes, high production costs, and are prone to cracking at the silver-copper interface, resulting in low yields. Achieving high bonding strength while maximizing silver savings has long been a challenge in the industry, becoming a major obstacle to the development of fuses.

[0004] Layered composite materials refer to composite materials in which the reinforcing phases are layered and stacked, that is, the reinforcing phases are arranged in parallel layers, and the layers are connected by the matrix material. The strength of layered composites is achieved through large deformation and diffusion annealing heat treatment. However, in lateral composites, cracks are easily generated at the silver-copper interface during the rolling process, resulting in poor lateral bonding strength. Inaccurate silver layer positioning also leads to less silver saving.

[0005] Patent CN101670365B discloses a method for preparing a double-sided inlaid composite strip. This patent involves creating strip-shaped through holes along the length of a strip-shaped copper plate, inlaying silver-copper alloy / silver into these holes to form a composite plate, vacuum brazing the composite plate, and then cold rolling, annealing, and precision rolling to the finished product. However, because this method uses cold rolling after vacuum brazing, under the high pressure of the rollers, ordinary layered composites (i.e., top and bottom pressing) suffer from delamination and cracking at the composite joints due to the lack of left and right side protection.

[0006] The applicant previously disclosed a method for preparing a side-coated silver-copper composite strip in patent CN102814324B. This patent involves machining one or more grooves along the length of a copper plate, placing a silver plate into the grooves, and then performing large-variable cold rolling, diffusion annealing, and a second cold rolling to prepare the silver-copper composite strip. Because this method involves placing the silver plate in grooves on the copper plate surface, during cold-pressing and deformation rolling, under the large deformation of the upper and lower rollers, one side lacks copper layer protection. Under the pressure of the upper and lower rollers, the side with copper layer protection deforms less, while the other side deforms more. Simultaneously, delamination and cracking may occur at the composite joint. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings and deficiencies of the existing technology and to provide a method for preparing multilayer lateral composite strip for fuses. The technical solution adopted by this invention includes the following steps:

[0008] S1. Oxygen-free copper is added to a vacuum induction melting furnace and cast into a plate with a length of A, a width of B, and a thickness of C. N square grooves extending along the length A are provided on one side of the plate formed by the width B and the thickness C. The length a of a single square groove is less than A, the width b is less than B / N, and the thickness c is less than C. That is, the square groove does not penetrate the plate, so that each square groove has only one opening on the side formed by the width B and the thickness C.

[0009] S2. Fill the square groove in S1 with N cleaned silver plates to form a multi-layer board;

[0010] S3. Place the multi-layer board described in S2 into a heating furnace filled with protective gas, and then place the heated board into an extruder for lateral hot pressing.

[0011] S4. Place the multi-layer sheet described in S3 into a heating furnace filled with protective gas, and hot-roll the heated sheet into a blank; hot rolling is performed using concave and convex rollers, fixing the sheet left and right inside the concave rollers, so that the convex rollers only press down along the length of the sheet to deform it;

[0012] S5. Mill away the upper and lower pure copper planes of the multilayer board described in S4, which are composed of length A and width B, until pure silver is visible.

[0013] S6. Roughly roll the multilayer sheet described in S5, place the rough-rolled sheet in a protective gas heating furnace for protective annealing, cool to room temperature, and then remove and finish roll. Repeat the annealing and finish rolling process until the finished product is obtained. Obtain lateral composite strip for fuses.

[0014] Preferably, in step S1, oxygen-free copper is added to a vacuum melting furnace, and a vacuum is started. After the vacuum degree reaches 5 x 10-3 Pa, the material is energized. When all the metal is melted and no bubbles escape from the surface of the molten pool, the melting process enters the refining stage. The refining time is 10-20 minutes. The material is then poured into a special mold. After it has completely cooled, the vacuuming is stopped. The riser is removed and the square tank is cleaned.

[0015] Preferably, in step S2, a silver plate with a negative tolerance dimension for the square groove is filled into the square groove;

[0016] Preferably, in S3, the protective heating conditions are as follows: the protective gas is argon, the argon concentration is 1.784 kg / m³, the argon pressure is 0.2 MPa, the temperature is 600-700℃, and the holding time is 3-5 h; the extruder hot repressing is performed: the extrusion cylinder and the hot repressing pad are heated to 350-600℃, and the holding time is 2-6 h. The bonding force between the interfaces is improved through thermal diffusion between metal atoms and hot repressing.

[0017] Preferably, in step S4, the protective heating conditions are as follows: the protective gas is argon, with an argon concentration of 1.784 kg / m³, an argon pressure of 0.2 MPa, a temperature of 600-700℃, and a holding time of 3-5 hours. The hot rolling conditions are as follows: the lower roll is a concave roll, and the upper roll is a convex roll. The heated multilayer sheet is placed in the concave roll, with an initial deformation of more than 50%, and subsequent deformations controlled at 20%. The initial deformation refers to the ratio of the change in cross-sectional area of ​​the rolled multilayer sheet before and after rolling to the area of ​​the multilayer sheet before rolling. The deformation per pass refers to the ratio of the change in cross-sectional area of ​​the multilayer sheet per pass to the cross-sectional area of ​​the multilayer sheet before rolling. The hot-rolled billet is placed in an argon-protected furnace and cooled to room temperature before being removed from the furnace. The concave and convex rolls effectively control lateral deformation, improving the bonding strength of the side composite.

[0018] Preferably, in step S6, the milled multilayer board is rough rolled, and the rough rolled board is placed in a protective gas heating furnace for annealing. The annealing conditions are: the protective gas is argon, the argon concentration is 1.784 kg / m³, the argon pressure is 0.2 MPa, the temperature is 600-700℃, the holding time is 3-5 h, and the board is cooled to room temperature before being removed from the furnace; then it is fine rolled and annealed until the finished product is obtained.

[0019] The beneficial effects of this invention are as follows: ① It uses non-penetrating square holes, with copper layers for fixation and protection on both the top and bottom surfaces; ② It uses concave and convex rollers, with the composite plate fixed left and right inside the concave rollers, and the convex rollers pressing down, deforming only along the length of the plate, thus ensuring lateral composite strength; ③ It uses oxygen-free copper vacuum melting and degassing, which can effectively ensure the gas content of the copper, and is cast into shape by molds, which is simpler and more convenient than the grooving method of copper plates, and is less prone to bubbling; ④ It uses extrusion hot pressing, which improves the bonding force between interfaces through thermal diffusion between metal atoms and hot repressing. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0021] Figure 1 shows the plate material cast by vacuum melting;

[0022] Figure 2 shows the concave and convex rolls used for rolling blanks. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0024] The directional and positional terms used in this invention, such as "up," "down," "front," "back," "left," "right," "inner," "outer," "top," "bottom," and "side," are merely for reference to the accompanying drawings. Therefore, the directional and positional terms used are for illustrating and understanding this invention, and not for limiting the scope of protection of this invention.

[0025] Example 1

[0026] A method for preparing a multilayer lateral composite strip includes the following steps:

[0027] a. Add oxygen-free copper to the vacuum melting furnace and begin evacuating the furnace until the vacuum level reaches 5 x 10⁻⁶. -3 After Pa, the molten metal is energized and melted. When all the metal has melted and no bubbles escape from the surface of the molten pool, the smelting process enters the refining stage, which lasts for 10 minutes. The metal is then poured into a special mold to form a plate with length A, width B, and thickness C. This plate has the following characteristics: there are square grooves in the width B and thickness C directions that do not penetrate to the bottom. The length of a single square groove is a < A, the width is b < B / N, and the thickness is c < C. The number of square grooves N depends on the customer's requirements. After complete cooling, the vacuuming is stopped; the risers are removed and the square grooves are cleaned.

[0028] b. Fill the cleaned square groove with N negative tolerance silver plates after surface cleaning to form a plate;

[0029] C. Place the multilayer sheet described in b into a heating furnace filled with protective gas, and then place the heated sheet into an extruder for hot pressing. The protective heating conditions are: the protective gas is argon, the argon concentration is 1.784 kg / m³, the argon pressure is 0.2 MPa, the temperature is 600℃, and the holding time is 3 hours. The hot pressing in the extruder is carried out at a temperature of 350℃ for the extrusion cylinder and the hot pressing pad, and the holding time is 2 hours. The bonding force between the interfaces is improved through thermal diffusion between metal atoms and hot pressing.

[0030] d. Place the sheet material into a heating furnace with a protective gas supply, and hot-roll the heated sheet material into a billet. Protective heating conditions: the protective gas is argon, argon concentration: 1.784 kg / m³, argon pressure: 0.2 MPa, temperature: 600℃, holding time: 3 hours. Hot rolling conditions: the lower roll is a concave roll, the upper roll is a convex roll. Place the heated multilayer sheet into the concave roll. The initial deformation is greater than 50%, and subsequent deformations are controlled at 20%. The initial deformation refers to the ratio of the change in cross-sectional area of ​​the rolled multilayer sheet before and after rolling to the area of ​​the multilayer sheet before rolling. The deformation per pass refers to the ratio of the change in cross-sectional area of ​​the multilayer sheet in each rolling pass to the cross-sectional area of ​​the multilayer sheet before rolling. Place the hot-rolled billet into an argon-protected furnace, cool to room temperature, and then remove it from the furnace. The concave and convex rolls can effectively control lateral deformation and improve the lateral composite bonding strength.

[0031] e. Mill away the two pure copper surfaces (length A, width B) of the multilayer board described in d to reveal pure silver.

[0032] f. The milled multilayer board is rough rolled, and the rough rolled board is placed in a protective gas heating furnace for annealing. Annealing conditions: the protective gas is argon, the argon concentration is 1.784 kg / m³, the argon pressure is 0.2 MPa, the temperature is 600℃, the holding time is 3h, and the board is cooled to room temperature before being removed from the furnace; finish rolling and annealing are performed until the finished product is obtained.

[0033] Example 2

[0034] a. Add oxygen-free copper to the vacuum melting furnace and begin evacuating the furnace until the vacuum level reaches 5 x 10⁻⁶. -3 After Pa, the molten metal is energized. When all the metal has melted and no bubbles escape from the surface of the molten pool, the smelting process enters the refining stage, which lasts for 20 minutes. The metal is then poured into a special mold (cast into a plate with length A, width B, and thickness C. This plate has the following characteristics: there are square grooves in the width B and thickness C directions that do not penetrate to the bottom. The length of a single square groove is a < A, the width is b < B, and the thickness is c < C. The number of square grooves N depends on the customer's requirements). After complete cooling, the vacuuming is stopped; the risers are removed and the square grooves are cleaned.

[0035] b. Fill the cleaned square groove with N negative tolerance silver plates after surface cleaning to form a plate;

[0036] C. Place the multilayer sheet described in b into a heating furnace filled with protective gas, and then place the heated sheet into an extruder for hot pressing. The protective heating conditions are: the protective gas is argon, the argon concentration is 1.784 kg / m³, the argon pressure is 0.2 MPa, the temperature is 700℃, and the holding time is 5h; the hot pressing in the extruder is carried out by heating the extrusion cylinder and the hot pressing pad at 600℃ for 6h. The bonding force between the interfaces is improved through thermal diffusion between metal atoms and hot pressing.

[0037] d. Place the sheet material into a heating furnace with a protective gas supply, and hot-roll the heated sheet material into a billet. Protective heating conditions: the protective gas is argon, argon concentration: 1.784 kg / m³, argon pressure: 0.2 MPa, temperature: 700℃, holding time: 5 hours. Hot rolling conditions: the lower roll is a concave roll, the upper roll is a convex roll. Place the heated multilayer sheet into the concave roll. The initial deformation is greater than 50%, and subsequent deformations are controlled at 20%. The initial deformation refers to the ratio of the change in cross-sectional area of ​​the rolled multilayer sheet before and after rolling to the area of ​​the multilayer sheet before rolling. The deformation per pass refers to the ratio of the change in cross-sectional area of ​​the multilayer sheet in each rolling pass to the cross-sectional area of ​​the multilayer sheet before rolling. Place the hot-rolled billet into an argon-protected furnace, cool to room temperature, and then remove it from the furnace. The concave and convex rolls can effectively control lateral deformation and improve the bonding strength of the side composite.

[0038] e. Mill away the two pure copper surfaces (length A, width B) of the multilayer board described in d to reveal pure silver.

[0039] f. The milled multilayer board is rough rolled, and the rough rolled board is placed in a protective gas heating furnace for annealing. Annealing conditions: the protective gas is argon, the argon concentration is 1.784 kg / m³, the argon pressure is 0.2 MPa, the temperature is 700℃, the holding time is 5h, and the board is cooled to room temperature before being removed from the furnace; finish rolling and annealing are performed until the finished product is obtained.

[0040] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a multilayer lateral composite strip for fuses, characterized in that... Includes the following steps: S1. Oxygen-free copper is added to a vacuum induction melting furnace and cast into a plate with length A, width B, and thickness C. N square grooves extending along length A but not penetrating the plate are formed on one side of the plate, where the width B and thickness C are equal to the length of the groove, a < A, width b < B / N, and thickness c < C. S2. Several cleaned silver plates are filled into the square grooves in S1 to form a multi-layer plate. S3. The multi-layer plate from S2 is placed in a heating furnace filled with protective gas, and the heated plate is then placed in an extruder. Lateral hot pressing forming; S4, the multi-layer sheet described in S3 is placed in a heating furnace with protective gas, and the heated multi-layer sheet is hot rolled into a blank; hot rolling uses concave and convex rollers, the multi-layer sheet is fixed left and right in the concave rollers, and the convex rollers are pressed down only along the length direction of the multi-layer sheet to deform it; S5, the upper and lower pure copper surfaces composed of length A and width B of the multi-layer sheet described in S4 are milled off until pure silver is visible; S6, the multi-layer sheet described in S5 is rough rolled, annealed, and fine rolled, and annealed and fine rolled repeatedly until a finished product is obtained, resulting in a multi-layer lateral composite strip for fuses.

2. The method for preparing a multilayer lateral composite strip for fuses according to claim 1, characterized in that: In step S1, oxygen-free copper is added to the vacuum melting furnace, and vacuuming begins, reaching a vacuum level of 5×10⁻⁶. -3 After Pa, the molten metal is energized and melted. When all the metal has melted and no bubbles escape from the surface of the molten pool, the smelting process enters the refining stage, which takes 10-20 minutes. The metal is then poured into a special mold and vacuuming is stopped after it has completely cooled. The risers are removed and the square tank is cleaned.

3. The method for preparing a multilayer lateral composite strip for a fuse according to claim 1, characterized in that: In step S2, a silver plate with a negative tolerance dimension relative to the square groove is filled into the square groove.

4. The method for preparing a multilayer lateral composite strip for a fuse according to claim 1, characterized in that: In S3, the specific conditions for the protective gas are: inert gas protection, temperature: 600-700℃, and holding time: 3-5h; the specific conditions for hot repressing with an extruder are: heating temperature of the extrusion cylinder and hot repressing pad block: 350-600℃, and holding time: 2-6h.

5. The method for preparing a multilayer lateral composite strip for a fuse according to claim 1, characterized in that: In S4, the specific conditions for the protective gas are: inert gas protection, temperature: 600-700℃, and holding time: 3-5h; the hot rolling conditions are: the lower roll is a concave roll, the upper roll is a convex roll, the heated multilayer sheet is placed in the concave roll, the initial deformation is greater than 50%, and then each time it is controlled at 20%.

6. The method for preparing a multilayer lateral composite strip for a fuse according to claim 1, characterized in that: In step S6, the multilayer sheet with exposed silver layer is rough rolled, and the rough rolled sheet is placed in a protective gas and annealed in a heating furnace. The annealing conditions are: the protective gas is argon, the temperature is 600-700℃, the holding time is 3-5h, and the sheet is cooled to room temperature before being taken out of the furnace. The sheet is then fine rolled and annealed until the finished product is obtained.

7. A method for preparing a multilayer lateral composite strip for a fuse according to any one of claims 1-6, characterized in that: The specific conditions for inert gas protection are as follows: the protective gas is argon, the argon concentration is 1.784 kg / m³, and the argon pressure is 0.2 MPa.

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