Equipment wire clamp and preparation method thereof

Abstract

The invention relates to the technical field of electric power fittings, in particular to an equipment wire clamp and a preparation method thereof.The equipment wire clamp comprises an aluminum substrate, one end of the aluminum substrate is in bolted connection with a plurality of glands, the other end of the aluminum substrate is provided with a welding groove, a copper plate is welded in the welding groove, and a welding layer formed by brazing paste for welding is arranged between the aluminum substrate and the copper plate; the brazing paste comprises solder alloy powder and soldering flux according to the mass ratio of (7-8): 1; the solder alloy powder comprises 7%-9% of nickel powder, 4%-6% of zinc powder, 0.5%-0.9% of nano titanium carbide and the balance tin powder. The soldering flux comprises the following raw materials of, by mass, 8%-10% of ethylene-vinyl acetate copolymer, 12%-15% of rosin, 23%-27% of activating agents, 1%-2% of surface active agents, 0.8%-1.5% of film forming agents, 4%-6% of thixotropic agents, 0.2%-0.5% of zinc fluoborate and the balance solvents. And the copper-aluminum welding strength in the copper-aluminum equipment wire clamp is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electric power fittings, in particular to a device wire clamp and a preparation method thereof. BACKGROUND

[0002] The device wire clamp is used for connecting the outgoing terminal plate of an electrical device (such as a transformer, a circuit breaker, a mutual inductor, a disconnector, a wall bushing, etc.) to the down lead of an overhead conductor of a power distribution line, and the most commonly used device wire clamp is a copper-aluminum device wire clamp. Because of the differences in chemical activity and electrical conductivity between copper and aluminum, if the two are directly connected, an original cell reaction is likely to occur at the contact surface, resulting in electrochemical corrosion, increased contact resistance at the connection part, heating, and fracture, which further leads to power failures such as wire breakage, short circuit, and power outage, and seriously endangers the safe and stable operation of the power equipment.

[0003] At present, the copper-aluminum device wire clamp on the market mainly adopts welding or casting connection. However, this type of connection cannot form a metallurgical bond at the copper-aluminum joint surface, and the weld seam, as a weak link in the joint structure, has low mechanical strength and is prone to cracks and cracking, which leads to equipment damage and power outage accidents. SUMMARY

[0004] In order to improve the strength of the copper-aluminum welding in the copper-aluminum device wire clamp, the application provides a device wire clamp and a preparation method thereof.

[0005] In a first aspect, the application provides a device wire clamp, which adopts the following technical scheme: A device wire clamp, comprising an aluminum base plate, a plurality of gland nuts are bolted to one end of the aluminum base plate, a welding groove is arranged at the other end of the aluminum base plate, and a copper plate is welded in the welding groove; a welding layer formed by a brazing paste is arranged between the aluminum base plate and the copper plate. The brazing paste comprises a solder alloy powder and a flux in a mass ratio of (7-8) : 1; the solder alloy powder comprises raw materials in the following mass percentages: nickel powder 7-9%, zinc powder 4-6%, nano-titanium carbide 0.5-0.9%, and the balance being tin powder; and the flux comprises raw materials in the following mass percentages: ethylene-vinyl acetate copolymer 8-10%, rosin 12-15%, activator 23-27%, surfactant 1-2%, film-forming agent 0.8-1.5%, thixotropic agent 4-6%, zinc fluoborate 0.2-0.5%, and the balance being a solvent.

[0006] By adopting the above technical scheme, the weld is wrapped up by adopting the sinking brazing process through the welding groove, the entry of air and water into the weld can be reduced, and the spreadability of the brazing paste can be improved by adding nickel in the solder alloy powder of the brazing paste, and the expansion rate is improved; the melting point of the brazing paste can be reduced by zinc powder, and the capillary filling is promoted; the grain size can be refined by nano-titanium carbide, and the welding strength is improved; at the same time, the activator and the surfactant in the flux, and the thixotropic agent can cooperate with each other, the spreadability of the brazing paste on the aluminum / copper surface can be significantly improved, and the air hole defect can be reduced; by the welding structure design of the aluminum substrate and the improvement of the brazing paste, the copper-aluminum dissimilar welding strength is greatly improved, and the quality of the equipment clamp is greatly improved.

[0007] Preferably, the nickel powder is a nickel powder loaded with graphene oxide on the surface.

[0008] By adopting the above technical scheme, the nickel powder is loaded with graphene oxide on the surface, on the one hand, the high electron mobility of graphene oxide can improve the conductive performance of the welding point; on the other hand, the graphene oxide coated nickel powder can isolate air and prevent the high-temperature oxidation of nickel powder, reducing the problem of increased contact resistance caused by oxidation; on the other hand, as an interface reinforcing phase, graphene oxide can also relieve stress cracking caused by the difference in thermal expansion coefficient between aluminum and copper; in many ways, the welding strength is improved.

[0009] Preferably, the nickel powder loaded with graphene oxide on the surface is prepared by reacting the nickel powder with a cationic surfactant and then reacting with graphene oxide.

[0010] By adopting the above technical scheme, the nickel powder surface can be charged by cationic surfactant treatment, and then adsorbed on the surface of the nickel powder by electrostatic attraction with graphene oxide. This method is very easy to operate and efficient, and the concentration of graphene oxide dispersion can be judged by color with the naked eye.

[0011] Preferably, the surfactant is polyglyceryl-3 polydimethylsiloxyethyl dimethicone.

[0012] By adopting the above technical scheme, polyglyceryl-3 polydimethylsiloxyethyl dimethicone can be anchored on the surface of metal particles through siloxane bond, and at the same time, steric hindrance effect can be formed by polyglycerol chain to prevent the aggregation of metal particles, and the interfacial tension between metal particles and flux can be reduced, the uniform dispersion of nanoparticles can be improved, especially for the dispersion of nano-titanium carbide; and it is found that it can improve the interaction between metal particles, reduce internal friction, reduce the viscosity of the system, and has a significant effect on the improvement of spreadability; it can also effectively reduce the sedimentation and stratification of metal particles, and improve the stability of the brazing paste.

[0013] As preferred: the activator is a mixture of triethanolamine and carboxyl-terminated hyperbranched polyester, and the mass ratio of triethanolamine and carboxyl-terminated hyperbranched polyester is 1:(3-5).

[0014] By adopting the technical scheme, the carboxyl-terminated hyperbranched polyester is compounded to efficiently and clearly remove the oxide film on the aluminum surface, prevent re-oxidation, and the hyperbranched polymer has very low viscosity, can penetrate more into the surface of the welding part, and improve the wetting effect.

[0015] As preferred: the solvent is a mixture of glycerol, ethylene glycol methyl ether and diethylene glycol monobutyl ether, and the mass ratio is 3:2:3.

[0016] By adopting the technical scheme, the raw materials in the flux are better dissolved in the solvent, and the uniformity of the system is stronger.

[0017] As preferred: the preparation method of the brazing paste is as follows: The rosin in the flux is stirred and mixed with the solvent, and heated to completely dissolve the rosin, then the ethylene-vinyl acetate copolymer is added, stirred to dissolve, then the activator and the surfactant are added, stirred to dissolve, heated to 65-75 DEG C, then the thixotropic agent is added, stirred uniformly to obtain the flux, then the solder alloy powder is added, and the stirrer is used to mix uniformly to prepare the brazing paste.

[0018] By adopting the technical scheme, the solder alloy powder is added to the flux after the raw materials in the flux are gradually dissolved, and then stirred to prepare the brazing paste, so that the preparation method is simple and suitable for mass production.

[0019] As preferred: the shape of the gland is "W" type.

[0020] By adopting the technical scheme, the "W" type gland can form a reaction force, and the nut can be prevented from falling off after the bolt is installed.

[0021] In a second aspect, the application provides a preparation method of a device wire clamp, which adopts the following technical scheme: A preparation method of a device wire clamp, comprising the following steps: S1, groove milling: grooves are milled on the aluminum substrate to obtain welding grooves, the groove depth is 1.5-2.5 mm, and the surface roughness is not greater than 3.2, and then polishing is performed; S2, chemical etching: the welding groove part of the aluminum substrate is soaked in a sodium hydroxide aqueous solution, the temperature is kept at 60-70 DEG C, then washed with clean water, soaked in a nitric acid solution, taken out and dried after welding, and used; S3, polish the welding surface of the copper plate, then place it in alcohol for cleaning, and complete the welding within one hour after drying; S4, the oxygen pressure of flame brazing is 3-5 MPa, the acetylene flow is 10-20 L / min, the welding time is 1-2 min, first brush the brazing paste evenly on the inner wall of the welding groove, then paste the copper plate into the welding groove after brushing the brazing paste around the copper plate, press the block on the copper plate, the block is provided with a weight sensor, and the gravity is displayed on the display in real time, the welding gap is controlled to be 0.05-0.07 mm by adjusting the weight of the block, the brazing gun heats the bottom of the work, and brazing is performed; S5, post-welding treatment: after the crude product after welding is immersed in clean water, the excess part is removed, and the device wire clamp is prepared after polishing.

[0022] By adopting the above technical scheme, the oxidation layer of the aluminum substrate can be removed well through pretreatment, and the welding quality is improved; by adopting the customized sheet-shaped welding sheet, it is not necessary to use an electrode to go around the welding seam, the labor intensity is reduced, the welding efficiency is improved, and the post-welding area is increased by 5%-10%; the weight-adjustable block design is adopted, and the gravity sensor is arranged thereon, different weights can be set according to different products, and the welding gap range after welding is guaranteed; the sinking brazing process is adopted, the welding seam is wrapped up, the polishing process is used to further fill and close the exposed part, and the entry of air and water into the welding seam is reduced.

[0023] In summary, the present application has at least one of the following beneficial technical effects: 1. By using the sinking brazing process, the welding seam is wrapped up, the entry of air and water into the welding seam can be reduced, nickel is added to the solder alloy powder of the brazing paste, the spreadability of the brazing paste is improved, and the expansion rate is improved; the melting point of the brazing paste is reduced by zinc powder, and the capillary filling is promoted; nano titanium carbide can refine the grain and improve the welding strength; at the same time, the activator and surfactant in the flux, and the thixotropic agent can significantly improve the spreadability of the brazing paste on the aluminum / copper surface, and reduce the air hole defect; through the welding structure design of the aluminum substrate and the improvement of the brazing paste, the copper-aluminum dissimilar metal welding strength is greatly improved, and the quality of the device wire clamp is greatly improved.

[0024] 2. The brazing paste prepared by the present application is used for dissimilar metal welding of copper and aluminum, and the welding point fracture strength is 67.8-78.1 N / mm 2 , the welding point shear strength is 74.7-87.5 N / mm 2 , and at the same time, the expansion rate of the brazing paste is maintained at 93.7-96.3%; it shows that the brazing paste has very good spreadability, and after copper-aluminum welding, the welding strength is strong, which can greatly improve the quality of the device wire clamp. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A structural schematic diagram of a device clamp according to Embodiment 1 of the present application.

[0026] Figure 2 A structural schematic diagram of a grommet.

[0027] Figure 3 A structural schematic diagram of a welding layer.

[0028] Reference signs: 1, aluminum substrate; 2, grommet; 3, copper plate; 4, welding layer; 5, wire. DETAILED DESCRIPTION

[0029] The present application will be further described in detail below in combination with specific contents.

[0030] Raw materials The raw materials used in the present application are all commercially available, among which, the rosin is rosin modified with acrylic acid, purchased from Jiangsu Lunfeng Synthetic Technology Co., Ltd.; the polyglyceryl-3 polydimethylsiloxyethyl dimethicone is purchased from Shin-Etsu Silicone International Trade (Shanghai) Co., Ltd., with a model number of KF-6106; the hydrogenated castor oil is purchased from Shanghai Yunhe Material Technology Co., Ltd.; the ethylene-vinyl acetate copolymer is purchased from Dongguan Yuehaoxuan Plastic Co., Ltd.; the carboxyl-terminated hyperbranched polyester has a model number of HyPer C102; and the zinc fluoroborate is purchased from Shandong Yuncheng Hui Nu Chemical Co., Ltd. EMBODIMENTS

[0031] Embodiment 1 A device clamp, as shown in Figure 1 and Figure 2 , comprises an aluminum substrate 1, a plurality of grommets 2 are bolted to one end of the aluminum substrate 1, and the grommets 2 are in a “W” shape. As shown in Figure 1 and Figure 3 , a welding groove (not shown in the figure) is provided at the other end of the aluminum substrate 1, a copper plate 3 is welded in the welding groove, and a welding layer 4 formed by brazing paste used for welding is between the aluminum substrate 1 and the copper plate 3. When the device clamp is used, the wire 5 is placed on the aluminum substrate 1, and then the grommets 2 are fixed by bolts, so that the wire 5 can be fixed between the aluminum substrate 1 and the grommets 2. Moreover, the grommets 2 in a “W” shape can form a counterforce, so that the nut is prevented from falling off after the bolts are installed. Among them, the material of the aluminum substrate 1 is pure aluminum 1060; and the material of the copper plate 3 is T2 copper.

[0032] Among them, the brazing paste comprises a flux and a solder alloy powder, and the preparation method of the brazing paste is as follows: S1. The solder alloy powder includes tin powder, nickel powder, zinc powder, and nano-titanium carbide. The mass percentage of each raw material is as follows: 8% nickel powder, 5% zinc powder, 0.7% nano-titanium carbide, and the balance is tin powder. The nickel powder, zinc powder, nano-titanium carbide, and tin powder are mixed evenly to obtain the solder alloy powder. The average particle size of nano-titanium carbide is 50nm; the average particle size of nickel powder is 15um. S2. The flux comprises the following raw materials in the following mass percentages: 9.5% ethylene-vinyl acetate copolymer, 13.5% rosin, 25% activator, 1.5% surfactant, 1% film-forming agent, 4.5% thixotropic agent, 0.3% zinc fluoroborate, and the balance being solvent; wherein, the activator is a mixture of triethanolamine and carboxyl-terminated hyperbranched polyester in a mass ratio of 1:4; the surfactant is polyglycerol-3-dimethylsiloxane; the film-forming agent is polyethylene glycol, PEG-2000; the thixotropic agent is hydrogenated castor oil; and the solvent is a mixture of glycerol, ethylene glycol methyl ether, and diethylene glycol monobutyl ether in a mass ratio of 3:2:3. S3. Prepare the flux paste according to a mass ratio of solder alloy powder to flux of 7.5:1, as follows: Rosin in the flux is stirred and mixed with solvent, and heated until the rosin is completely dissolved. Then, ethylene-vinyl acetate copolymer is added and stirred until dissolved. Then, activator and surfactant are added and stirred until dissolved. The temperature is raised to 70°C, thixotropic agent is added, and stirred evenly to obtain flux. Then, solder alloy powder prepared by S1 is added and mixed thoroughly and evenly using a mixer to obtain brazing paste.

[0033] The manufacturing process of the equipment wire clamp includes the following steps: S1. Milling groove: Mill a groove on the aluminum substrate 1 to obtain a welding groove with a groove depth of 2mm and a surface finish of no more than 3.2. S2. Polishing: Polish the inside of the welding groove, using sandpaper for rough polishing and cloth wheel for fine polishing; S3. Chemical texturing: Immerse the welding tank portion of the aluminum substrate 1 in a 15% sodium hydroxide aqueous solution, maintain the temperature at 60-70℃, immerse for 20 minutes, rinse with clean water, and then immerse in a 10% nitric acid solution. Remove and dry before use during welding. S4. Polish the welding surface of copper plate 3 gradually with 400 grit, 600 grit, 800 grit and 1200 grit sandpaper, then place it in alcohol and clean it with ultrasonic vibration to remove surface dust. Let it air dry naturally for later use. Complete the welding within one hour after drying. S5, flame brazing (acetylene and oxygen) oxygen pressure 3-5 MPa, acetylene flow 10-20 L / min, welding time 1-2 min, first brush uniform brazing paste on the inner wall of the welding groove, copper plate 3 around the brush brazing paste after paste into the welding groove, the pressure block is pressed on the copper plate 3, the pressure block is provided with a weight sensor, and the weight is displayed on the display in real time, the welding gap is controlled by fine-tuning the weight of the pressure block, the brazing gun is heated to the bottom of the work, brazing, liquid filler metal can wet the welding metal, and fill all the gaps, and achieve good intermetallic bonding between copper and aluminum materials, cool, and complete the welding; S6, post-welding treatment: after the welding of the crude product is immersed in water, the excess part is removed using a fine copper brush, and the crude product is polished using a polishing machine to obtain the device clamp; a small sample for inspection is cut out using a metallographic cutting machine, first coarsely polished using sandpaper, then finely polished using a polishing cloth, immersed in dilute hydrochloric acid with a mass fraction of 8-10% for 30 min, and the weld size is detected using a metallographic microscope, and the weld gap is required to be 0.05-0.07 mm.

[0034] Example 2 A device clamp, which is different from example 1 in that the nickel powder is replaced by equal mass of surface-loaded graphene oxide nickel powder, and the preparation method of the surface-loaded graphene oxide nickel powder is as follows: 5 g of nickel powder is soaked in 1000 mL of aqueous solution of cationic surfactant with a concentration of 1.5 g / L, the cationic surfactant is dodecyltrimethylammonium chloride, after stirring for 30 min, filtration, drying, then adding 500 mL of graphene oxide water dispersion with a concentration of 0.1 g / L, stirring for 15 min, then filtering, drying, to obtain surface-loaded graphene oxide nickel powder.

[0035] Example 3 A device clamp, which is different from example 1 in that the surfactant is equal mass of sodium dodecylbenzenesulfonate, and the remaining steps are the same as example 1.

[0036] Example 4 A device clamp, which is different from example 1 in that the activator is a mixture of triethanolamine and adipic acid with a mass ratio of 1:4, and the remaining steps are the same as example 1.

[0037] Example 5 A device clamp, which is different from example 1 in that no nano-titanium carbide is added to the solder alloy powder, and the remaining steps are the same as example 1.

[0038] Example 6 A device clamp, which is different from example 1 in that 0.05 g of graphene oxide is additionally added to the solder alloy powder, and the remaining steps are the same as example 1.

[0039] Comparative Example Comparative Example 1 A device wire clamp differs from Example 3 in that its solder alloy powder does not contain nano-titanium carbide, while the remaining steps are the same as in Example 3.

[0040] Performance testing Detection methods / test methods Soldering pastes were prepared according to the preparation methods of Examples 1-6 and Comparative Example 1, and then copper and aluminum were welded together using the soldering pastes according to the welding method described in Example 1. The results were then tested according to the following testing methods, and the test results are shown in Table 1.

[0041] The expansion rate, fracture strength, and shear strength of the solder joint shall be tested in accordance with the test methods in SJ / T11390-2009.

[0042] Table 1. Detection results of Examples 1-6 and Comparative Example 1 As can be seen from Examples 1-6, Comparative Example 1, and the test data in Table 1, the solder paste prepared in this application can be used for dissimilar metal welding of copper and aluminum, resulting in a weld joint fracture strength of 67.8-78.1 N / mm². 2 The shear strength of the weld joints is between 74.7 and 87.5 N / mm. 2 Meanwhile, the spread rate of the solder paste remained between 93.7% and 96.3%, indicating that the solder paste of this application has very good spreadability and strong welding strength after copper-aluminum welding, which can significantly improve the quality of equipment clamps.

[0043] The test data from Examples 1-2 show that by loading graphene oxide onto the surface of nickel powder, on the one hand, the high electron mobility of graphene oxide can improve the conductivity of the solder joint; on the other hand, the graphene oxide coating of nickel powder can isolate it from air, prevent the high-temperature oxidation of nickel powder, and reduce the problem of increased contact resistance caused by oxidation; furthermore, as an interface reinforcing phase, graphene oxide can also alleviate stress cracking caused by the difference in thermal expansion coefficients of aluminum and copper. These multiple effects work together to improve the welding strength. In addition, combined with the test data from Example 6, the addition of graphene oxide loaded onto the surface of nickel powder can improve its dispersion and the lubricity between nickel powder and the system, which is beneficial to improving the spread rate.

[0044] As can be seen from the detection data of Example 1 and Example 3, the polyglyceryl-3 polydimethylsiloxy hydroxyethyl dimethicone can be anchored on the surface of the metal particles through the silicon-oxygen bond, at the same time, form a steric hindrance effect through the polyglycerol chain to prevent the aggregation of the metal particles, and also can reduce the interfacial tension between the metal particles and the flux, improve the uniform dispersion of the nanoparticles, especially for the dispersion of nano-titanium carbide; and it is found that it can improve the interaction between the metal particles, reduce the internal friction, reduce the viscosity of the system, and has a significant effect on the improvement of the spreadability.

[0045] As can be seen from the detection data of Example 1 and Example 4, the use of carboxyl-terminated hyperbranched polyester for compounding can efficiently remove the oxide film on the surface of aluminum, prevent its re-oxidation, and the viscosity of the hyperbranched polymer is very low, which can penetrate more into the surface of the welding part to improve the wetting effect.

[0046] As can be seen from the detection data of Example 1 and Example 6, nano-titanium carbide can refine the grains and improve the welding strength. In combination with Example 3 and Comparative Example 1, the performance of the brazing paste of the present application needs to contain both nano-titanium carbide and polyglyceryl-3 polydimethylsiloxy hydroxyethyl dimethicone at the same time.

[0047] The specific embodiments are only an explanation of the present application, which is not a limitation of the present application, and those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, as long as the modifications are within the scope of the claims of the present application.

Claims

1. A device clip, characterized by: The application relates to an aluminum substrate (1) which is bolted at one end with a plurality of press covers (2) and is provided with a welding groove at the other end, and a copper plate (3) is welded in the welding groove; a welding layer (4) formed by brazing paste is arranged between the aluminum substrate (1) and the copper plate (3). The brazing paste comprises solder alloy powder and a flux in a mass ratio of 7-8:1; the solder alloy powder comprises raw materials in the following mass percentages: 7-9% of nickel powder, 4-6% of zinc powder, 0.5-0.9% of nano titanium carbide, and the balance of tin powder; the flux comprises raw materials in the following mass percentages: 8-10% of ethylene-vinyl acetate copolymer, 12-15% of rosin, 23-27% of an activator, 1-2% of a surfactant, 0.8-1.5% of a film forming agent, 4-6% of a thixotropic agent, 0.2-0.5% of zinc fluoroborate, and the balance of a solvent.

2. A device clip according to claim 1, wherein: The nickel powder is surface-loaded graphene oxide.

3. A device clip according to claim 2, wherein: The surface-loaded graphene oxide nickel powder is prepared by reacting nickel powder with a cationic surfactant and then with graphene oxide.

4. A device clip according to claim 1, wherein: The surfactant is polyglyceryl-3 polydimethylsiloxyethyl dimethicone.

5. A device clip according to claim 1, wherein: The activator is a mixture of triethanolamine and carboxyl-terminated hyperbranched polyester, and the mass ratio of the triethanolamine to the carboxyl-terminated hyperbranched polyester is 1:(3-5).

6. A device clip according to claim 1, wherein: The solvent is a mixture of glycerol, ethylene glycol methyl ether and diethylene glycol monobutyl ether in a mass ratio of 3:2:

3.

7. A device clip according to claim 1, wherein: The preparation method of the brazing paste is as follows: The rosin in the flux is stirred and mixed with the solvent, and then heated until the rosin is completely dissolved; then the ethylene-vinyl acetate copolymer is added and stirred until dissolved; then the activator and the surfactant are added and stirred until dissolved; after being heated to 65-75 DEG C, the thixotropic agent is added and stirred until uniform; the flux is obtained; then the solder alloy powder is added and uniformly mixed by using a stirrer to prepare the brazing paste.

8. A device clip according to claim 1, wherein: The press cover (2) is in the shape of a "W".

9. A method of making a device clip according to any one of claims 1 to 8, characterised in that: The method comprises the following steps: S1, groove milling: grooves are milled on the aluminum substrate (1) to form welding grooves, the groove depth is 1.5-2.5 mm, and the surface roughness is not greater than 3.2; then polishing is performed; S2, chemical etching: the welding groove part of the aluminum substrate (1) is soaked in a sodium hydroxide aqueous solution, the temperature is kept at 60-70 DEG C, then washed with clean water, soaked in a nitric acid solution, and taken out to dry after welding; S3, the welding surface of the copper plate (3) is polished, then placed in alcohol for cleaning, and dried to complete welding within one hour; S4, the oxygen pressure of flame brazing is 3-5 MPa, the acetylene flow is 10-20 L / min, the welding time is 1-2 min, the brazing paste is uniformly brushed on the inner wall of the welding groove, the copper plate is placed in the welding groove after being brushed with the brazing paste around the copper plate, a pressing block is pressed on the copper plate (3), the pressing block is provided with a weight sensor, and the weight is displayed on a display in real time; the weight of the pressing block is adjusted to control the welding gap to be 0.05-0.07 mm; the brazing gun is heated to the bottom of the workpiece to perform brazing; S5, post-welding treatment: the crude product after welding is soaked in clean water to remove the excess part, polished, and then the device clamp is prepared.

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