Near-spherical particle brazing filler metal and processing method and device thereof

Abstract

The present application relates to the technical field of brazing material processing, in particular to a kind of near-spherical particle brazing filler metal and its processing method and device.The processing method of near-spherical particle brazing filler metal includes the following steps: the brazing filler metal wire is pre-cut into similar pod shape, and laser absorption paint is coated at the joint of the pre-cut incision, then the joint of the incision is fused by laser, and near-spherical particle brazing filler metal is obtained.The present application is to pre-cut mechanically, and at the same time, high-energy absorption graphite paint is coated at the joint of the incision, and a laser generator is added at the back end to melt the fine wire and form near-spherical brazing filler metal.The method uses less equipment, has low energy consumption, high efficiency, high material utilization rate, basically no loss, the size of near-spherical brazing filler metal is easy to control, and uniformity is good.

Description

Technical Field

[0001] This invention relates to the field of brazing material processing technology, and more specifically, to a near-spherical brazing filler metal and its processing method and apparatus. Background Technology

[0002] Brazing is a method of welding in which a filler metal is placed on the base material to be welded. Heating melts the filler metal while the base material remains unmelted, forming a chemical-metallurgical bond at the interface. Brazing plays an irreplaceable role in connecting complex structures and precision joints. Filler metals are typically in the form of wires, sheets, strips, or powder. However, with the increasing complexity of structural components due to technological advancements, the required form of filler metal has become more diverse. Spherical filler metals, with their precise weight, are important for spot welding and fixing complex components. In this application, a pneumatic welding torch picks up the filler metal ball, and resistance welding is used to fix the workpiece. At this stage, the filler metal ball is not completely melted; subsequent heating melts it completely, achieving precision welding of complex components.

[0003] In existing technologies, brazing filler metal balls are generally prepared by cutting wire into granules, which are then ground into spherical particles. The grinding process results in significant material loss, and brazing filler metals typically contain precious or rare metals, leading to high material and processing costs. Grinding causes substantial material waste.

[0004] Laser cutting is an effective processing method, but different materials have different laser absorption rates. In particular, silver alloys and copper alloys have high laser reflectivity, requiring high laser power to form droplets into spheres. This increases equipment costs, reduces efficiency, and makes it difficult to control droplet size.

[0005] Therefore, it is of great significance to provide a method and apparatus for processing near-spherical brazing filler metal particles with low material loss, low energy consumption and controllable size.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The primary objective of this invention is to provide a method for processing near-spherical brazing filler metal particles, thereby addressing the technical problems of high material loss, high energy consumption, and difficulty in controlling the size of spherical filler metal in existing methods. The method of this invention requires less equipment, consumes less energy, is highly efficient, has high material utilization, and allows for easy control of the size and uniformity of the near-spherical filler metal.

[0008] The second objective of this invention is to provide a near-spherical particle brazing filler metal, which is prepared by the near-spherical particle brazing filler metal processing method described above.

[0009] A third objective of the present invention is to provide an apparatus for processing near-spherical particle brazing filler metal, which is applicable to the processing method of near-spherical particle brazing filler metal as described above.

[0010] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0011] A method for processing near-spherical solder particles includes the following steps:

[0012] The brazing wire is pre-cut into a pod shape, and a laser-absorbing coating is applied to the cut joint. Then, a laser is used to melt the cut joint to obtain the near-spherical brazing wire particles.

[0013] Preferably, the brazing wire includes any one of copper alloy wire, silver alloy wire, nickel alloy wire, and iron alloy wire.

[0014] Preferably, the diameter of the solder wire and the length of a single pre-cut segment are both matched with the diameter of the near-spherical solder particles.

[0015] Preferably, the diameter of the cut joint is 0.2mm-d / 2, where d is the diameter of the brazing wire.

[0016] Preferably, the laser-absorbing coating comprises the following components by weight percentage:

[0017] Graphite powder 40%-70%, high molecular organic materials 4%-8%, thickener 2%-5%, and solvent 20%-52%.

[0018] Preferably, the graphite powder has a particle size of less than 10 μm.

[0019] Preferably, the polymeric organic material includes at least one of polyacrylate, polyvinyl butyral, and polyvinylpyrrolidone.

[0020] Preferably, the thickener comprises methylcellulose and / or ethylcellulose.

[0021] Preferably, the solvent includes at least one selected from trichloroethylene, dichloroethylene, carbon tetrachloride, toluene, p-xylene, ethyl acetate, dimethyl sulfoxide, butyl acetate, methanol, ethanol, chloroform, and acetone.

[0022] Preferably, the power of the laser is 500-5000W.

[0023] A near-spherical particle brazing filler metal is prepared by the processing method of the near-spherical particle brazing filler metal described in any of the foregoing embodiments.

[0024] An apparatus for processing near-spherical brazing filler metal particles, applicable to the processing method of near-spherical brazing filler metal particles as described in any of the foregoing embodiments, comprising:

[0025] Two symmetrically arranged, adjustable horseshoe-shaped disc cutters are used to pre-cut the brazing wire passing through their gap. The horseshoe-shaped disc cutters include a disc and a plurality of horseshoe-shaped cutters fixed on the disc. The plurality of horseshoe-shaped cutters are evenly distributed around the circumference of the disc.

[0026] A laser-absorbing coating feeding device is used to supply laser-absorbing coating to the horseshoe-shaped cutter;

[0027] A laser generator, located downstream of the disc horseshoe-shaped cutter, is used to melt the pre-cut portion of the brazing wire;

[0028] The receiving bin is used to collect near-spherical brazing filler metal particles.

[0029] Preferably, the laser-absorbing coating feeding device includes a coating box and laser-absorbing coating inside the coating box. The side wall of the coating box near the horseshoe-shaped cutter is made of a flexible porous material. When the horseshoe-shaped cutter rotates, it passes through the coating box and comes into contact with the flexible porous material to pick up the laser-absorbing coating. When pre-cutting the brazing wire, the laser-absorbing coating is applied to the cut joint of the brazing wire.

[0030] Preferably, the flexible porous material includes any one of sponge, cotton, and absorbent paper.

[0031] Preferably, the viscosity of the laser-absorbing coating is 2000-5000 cP.

[0032] Preferably, the horseshoe-shaped cutter is made of any one of cemented carbide, high-speed steel, or superhard materials.

[0033] Preferably, the gap 'a' between the two disks satisfies the following conditions: a≥d, 0.2mm≤a-2h<d / 2, where d is the diameter of the brazing wire and h is the height of the horseshoe-shaped cutter head.

[0034] Preferably, the rotational linear velocity V1 of the horseshoe-shaped roller cutter and the wire feeding velocity V2 of the brazing wire satisfy the following relationship: V2=lNV1 / [π(D+2h)], where l is the length of a single pre-cut segment, N is the number of horseshoe-shaped cutters on a single disc, D is the diameter of the disc, and h is the height of the cutting head of the horseshoe-shaped cutter.

[0035] Preferably, the laser generator is a YAG laser generator or a semiconductor laser generator.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] The method of this invention first pre-cuts the wire into a shape similar to a bean pod, and coats the diameter change area with a laser-absorbing coating to form a high-energy absorption zone at the cut joint. Then, the diameter change area is melted by laser cutting to form a near-spherical brazing filler metal. This method of the invention does not require equipment such as cutting machines, ball-making machines, and ball-grinding machines, so it uses less equipment, has low cost, and high efficiency. In addition, the material utilization rate is high and there is basically no loss. The required laser power is low, and the energy consumption is significantly reduced compared to simply using laser to melt droplets into spheres. Moreover, the size of the obtained near-spherical brazing filler metal is controllable and the uniformity is good. Attached Figure Description

[0038] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 A process flow diagram for preparing near-spherical particle solder provided in an embodiment of the present invention;

[0040] Figure 2 This is a product image of the near-spherical brazing filler metal prepared in Example 1 of the present invention;

[0041] Figure 3 This is a product image of the near-spherical brazing filler metal prepared in Example 2 of the present invention.

[0042] Figure descriptions: 1-Disc horseshoe-shaped cutter; 11-Disc; 12-Horseshoe-shaped cutter; 2-Laser absorption coating feeding device; 3-Laser generator; 4-Receiving bin. Detailed Implementation

[0043] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0044] like Figure 1 As shown, the first aspect of the present invention provides a method for processing near-spherical solder particles, comprising the following steps:

[0045] The brazing wire is pre-cut into a pod shape, and a laser-absorbing coating is applied to the cut joint. Then, a laser is used to melt the cut joint, resulting in a near-spherical brazing wire particle.

[0046] After pre-cutting, the brazing wire is not completely severed. Its shape resembles a pod with multiple beans arranged in a continuous pattern. The distance from the central axis to different positions along the circumference is basically the same, preventing the brazing wire from being flattened. Pre-cutting can form multiple pre-cut segments of the same length, and the wire diameter becomes thinner at the cut joint between the pre-cut segments, with an arc-shaped transition at the diameter change. After melting the cut joint, it is easy to form a spherical shape. Applying a laser-absorbing coating to the cut joint can form a high-energy absorption zone at the thinnest diameter, which can be melted with relatively low laser power, resulting in low energy consumption. At the same time, since other parts without laser-absorbing coating have a high laser reflectivity, only the thinnest diameter cut joint has a high laser absorption rate. During laser melting, the cut joint can be better positioned, avoiding uneven brazing sphere size due to deviation. This makes it easy to control the size of the near-spherical brazing wire. The near-spherical shape in this invention also includes spherical shapes.

[0047] Traditional ball-making involves precision cutting to grind columnar particles into balls, requiring equipment such as cutting machines, ball-rolling machines, and ball-grinding machines. This process is complex, lengthy, and results in low material utilization, with material loss exceeding one-third, leading to significant waste of high-cost materials. In contrast, the method of this invention uses fewer devices, has lower production costs, higher material utilization, and virtually no material loss.

[0048] Traditional laser droplet formation requires high laser power, especially for silver and copper alloys which have high laser reflectivity, requiring even higher power. This increases equipment costs, reduces efficiency, and makes it difficult to control the size of the molten balls. If laser-absorbing coating is only applied to the cutting area, the coating melts only at the point of contact during laser cutting, leaving the uncut surface flat and unable to achieve spherical particle shearing. While coating the entire surface of the brazing wire with laser-absorbing coating and then using laser droplet formation can create spherical brazing wire and reduce laser power to some extent, the laser power remains high because the entire ball needs to be melted. Furthermore, full coating with laser-absorbing coating cannot provide positioning, the size of the brazing wire is difficult to control, and coating components can easily enter the molten brazing wire, forming impurities. The method of this invention overcomes these shortcomings, significantly reduces laser power and energy consumption, and the size of the near-spherical brazing wire is easy to control.

[0049] In some specific embodiments of the present invention, the brazing wire includes any one of copper alloy wire, silver alloy wire, nickel alloy wire, and iron alloy wire. The method of the present invention is particularly suitable for brazing wires with high laser reflectivity, such as copper alloy wire and silver alloy wire.

[0050] In some specific embodiments of the present invention, the wire diameter of the solder wire and the length of a single pre-cut segment are matched with the diameter of the near-spherical solder particles. The size of the solder wire and the pre-cut size can be determined according to the size of the required solder ball. In general, the wire diameter of the solder wire and the length of a single pre-cut segment can be set to be the same as the diameter of the required solder ball.

[0051] In some specific embodiments of the present invention, the diameter of the solder wire is 1-6 mm, for example, it can be any single value or a range of any two values ​​among 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, and 6 mm. In other embodiments, the diameter of the solder wire can also be other values ​​depending on the size of the desired solder ball.

[0052] In some specific embodiments of the present invention, the diameter of the cut joint is 0.2mm-d / 2, where d is the diameter of the brazing wire. Controlling the diameter of the cut joint to ≥0.2mm aims to avoid collision between the upper and lower cutters or deformation of the wire during pre-cutting. Controlling the diameter of the cut joint to not exceed 1 / 2 of the brazing wire diameter ensures a good pre-cutting effect to form a near-spherical brazing filler metal, while simultaneously reducing laser melting power.

[0053] In some specific embodiments of the present invention, the laser-absorbing coating comprises the following components by mass percentage:

[0054] Graphite powder 40%-70%, high molecular organic materials 4%-8%, thickener 2%-5%, and solvent 20%-52%.

[0055] Black graphite powder can improve laser absorption and form a high-energy absorption zone at the cut joint. The role of polymeric organic materials is to enhance the adhesion between the coating and the metal substrate. Furthermore, the low ash content and no residue of polymeric organic materials during the brazing process do not affect the welding effect. Thickeners are used to control the viscosity of the coating to meet the usage requirements.

[0056] In some embodiments, typically but not limitingly, for example, in laser-absorbing coatings, the mass percentage of graphite powder can be any one value or a range of any two values ​​from 40%, 50%, 60%, and 70%; the mass percentage of polymeric organic materials can be any one value or a range of any two values ​​from 4%, 5%, 6%, 7%, and 8%; the mass percentage of thickener can be any one value or a range of any two values ​​from 2%, 3%, 4%, and 5%; and the mass percentage of solvent can be any one value or a range of any two values ​​from 20%, 23%, 28%, 32%, 40%, 45%, and 52%.

[0057] In some specific embodiments of the present invention, the particle size of the graphite powder used is less than 10 μm, preferably less than 5 μm. Using graphite powder with a smaller particle size helps to ensure the uniformity of graphite powder coating.

[0058] In some specific embodiments of the present invention, the graphite powder used is flake graphite powder.

[0059] In some specific embodiments of the present invention, the polymeric organic materials used include at least one of polyacrylate, polyvinyl butyral, and polyvinylpyrrolidone; the above-mentioned polymeric organic materials have strong adhesion to metals, and the brazing process has low ash content and no residue, which does not affect the welding effect.

[0060] In some specific embodiments of the present invention, the thickeners used include methylcellulose and / or ethylcellulose.

[0061] In some specific embodiments of the present invention, the solvent used includes at least one selected from trichloroethylene, dichloroethylene, carbon tetrachloride, toluene, p-xylene, ethyl acetate, dimethyl sulfoxide, butyl acetate, methanol, ethanol, chloroform, and acetone.

[0062] In some specific embodiments of the present invention, the laser power required when using laser melting to cut the joint is 500-5000W. For example, it can be any one value or a range of any two values ​​among 500W, 800W, 1000W, 1500W, 2000W, 3000W, 4000W, and 5000W.

[0063] A second aspect of the present invention provides a near-spherical particle brazing filler metal, which is prepared by the processing method of the near-spherical particle brazing filler metal described in any of the foregoing embodiments.

[0064] like Figure 1 As shown, a third aspect of the present invention provides an apparatus for processing near-spherical solder particles, applicable to the processing method of near-spherical solder particles as described in any of the foregoing embodiments, comprising:

[0065] Two symmetrically arranged horseshoe-shaped cutters 1 with adjustable gap about the solder wire are used to pre-cut the solder wire passing through the gap between them. The horseshoe-shaped cutter 1 includes a disc 11 and a plurality of horseshoe-shaped cutters 12 fixed on the disc 11. The plurality of horseshoe-shaped cutters 12 are evenly distributed around the circumference of the disc 11.

[0066] Laser-absorbing coating feeding device 2 is used to supply laser-absorbing coating to horseshoe-shaped cutter 12;

[0067] Laser generator 3 is located downstream of the disc horseshoe-shaped cutter 1 and is used to melt the pre-cut part of the brazing wire.

[0068] The receiving bin 4 is used to collect near-spherical brazing filler metal particles.

[0069] During pre-cutting, the gap between the two disc horseshoe-shaped cutters 1 can be adjusted according to the wire diameter and pre-cutting depth of the brazing wire. The brazing wire passes through the gap between the two disc horseshoe-shaped cutters 1, and the two disc horseshoe-shaped cutters 1 rotate in opposite directions to perform pre-cutting. The pre-cutting process can ensure that the brazing wire is straight. During the rotation of the disc horseshoe-shaped cutters 1, the laser absorption coating feeding device 2 can coat the laser absorption coating onto the horseshoe-shaped cutter 12. After pre-cutting by the horseshoe-shaped cutter 12, the brazing wire forms a shape similar to a bean pod. The wire diameter becomes thinner at the cut joint, and the brazing wire is pressed with a layer of black laser absorption coating by the cutting head of the horseshoe-shaped cutter 12 at the thinner part, which is beneficial to energy absorption during subsequent laser cutting. The near-spherical brazing wire particles obtained after laser melting enter the receiving bin 4.

[0070] In some specific embodiments of the present invention, there are two laser absorption coating feeding devices 2, which are respectively matched with two disc horseshoe-shaped cutters 1.

[0071] In some specific embodiments of the present invention, the laser-absorbing coating feeding device 2 includes a coating box and laser-absorbing coating inside the coating box. The side wall of the coating box near the end of the horseshoe-shaped cutter 1 is made of a flexible porous material. The flexible porous material can adsorb the laser-absorbing coating. When the horseshoe-shaped cutter 12 rotates, it passes through the coating box and comes into contact with the flexible porous material. It picks up the laser-absorbing coating by squeezing it. When the brazing wire is pre-cut, the laser-absorbing coating is applied to the cut joint of the brazing wire. This device can realize automatic feeding of laser-absorbing coating during the pre-cutting process and achieve coating at the same time as pre-cutting. It is simple to operate and has high working efficiency.

[0072] In some specific embodiments of the present invention, the flexible porous material includes any one of sponge, cotton, and absorbent paper. The function of the flexible porous material is to adsorb the laser-absorbing coating and to be squeezed during contact with the horseshoe-shaped cutter 12, releasing the laser-absorbing coating and coating it on the cutter head.

[0073] In some specific embodiments of the present invention, the viscosity of the laser-absorbing coating is 2000-5000 cP. For example, it can be any single value or a range of any two values ​​from 2000 cP, 2500 cP, 3000 cP, 3500 cP, 4000 cP, 4500 cP, and 5000 cP. Excessive viscosity of the coating is detrimental to the adsorption of the flexible porous material; excessively low viscosity results in good fluidity of the coating, making it prone to seepage from the flexible porous material. Therefore, it is necessary to reasonably control the viscosity of the laser-absorbing coating.

[0074] In some specific embodiments of the present invention, the horseshoe-shaped cutter 12 is made of any one of cemented carbide, high-speed steel, or superhard materials. Multiple horseshoe-shaped cutters 12 on the same disk 11 may be made of the same material or different materials.

[0075] In some specific embodiments of the present invention, the gap 'a' between the two discs 11 satisfies the following conditions: a ≥ d, 0.2 mm ≤ a - 2h < d / 2, where d is the diameter of the solder wire and h is the height of the horseshoe-shaped cutter head, i.e., the length of the horseshoe-shaped cutter extending out of the disc. The gap 'a' between the two discs 11 refers to the minimum distance between the two discs 11. The purpose of controlling the disc gap a ≥ d is to prevent the solder wire from being flattened by the discs. a - 2h is the minimum gap between the heads of the two horseshoe-shaped cutters 1. The purpose of controlling a - 2h ≥ 0.2 mm is to prevent the upper and lower cutter heads from colliding or the solder wire from deforming. Controlling a - 2h < d / 2 is to ensure that the diameter at the cut joint is less than 1 / 2 of the initial diameter of the solder wire, so as to guarantee the pre-cutting effect.

[0076] In some specific embodiments of the present invention, the rotational linear velocity V1 of the disc horseshoe-shaped cutter 1 and the wire feeding velocity V2 of the brazing wire satisfy the following relationship: V2=lNV1 / [π(D+2h)], where l is the length of a single pre-cut segment, N is the number of horseshoe-shaped cutters on a single disc, D is the diameter of the disc, and h is the height of the horseshoe-shaped cutter head.

[0077] In some specific embodiments of the present invention, the laser generator is a YAG laser generator or a semiconductor laser generator.

[0078] The following detailed description of some embodiments of the present invention is provided in conjunction with specific examples. Unless otherwise specified, all raw materials used in the embodiments can be commercially available. The following embodiments are all implemented using the apparatus provided by the present invention.

[0079] Example 1

[0080] The balls are made using BAg72Cu alloy wire with a diameter of 3mm.

[0081] The horseshoe-shaped cutter is made of YT carbide, with a disc diameter of 30mm and a cutter head height h of 3mm. Four cutter heads are welded on the cutter disc, and the gap (a-2h) between the two disc horseshoe-shaped cutters is adjusted to 1mm.

[0082] Select flake graphite powder with a particle size <5μm, and mix 60% graphite powder, 5% polyacrylate, 3% ethyl cellulose, 20% trichloroethylene, and 12% carbon tetrachloride by mass percentage to form a uniform black coating with a viscosity of 3200 cP.

[0083] The disc horseshoe-shaped cutter rotates in opposite directions, with the laser-absorbing coating feeding device placed to the side. During the rolling process, the horseshoe-shaped cutter head adheres to the laser-absorbing coating, which is then applied to the interface joint during pre-cutting. The disc horseshoe-shaped cutter pre-cuts the brazing wire, adjusting the wire feed speed to 5 mm / s and the linear speed of the disc horseshoe-shaped cutter to 47.1 mm / s, pre-cutting the brazing wire into a pod shape. The length l of a single pre-cut segment is 3 mm, and the diameter of the brazing wire cut joint is 1 mm. Black laser-absorbing coating adheres to the brazing wire cut joint.

[0084] Adding a 1000W YAG laser generator to the rear end of the brazing wire can melt the wire into a near-spherical brazing wire with a diameter of 3mm. The resulting near-spherical brazing wire products include... Figure 2 As shown 。

[0085] Example 2

[0086] The balls are made using BAg45CuZn alloy wire with a diameter of 1mm.

[0087] The horseshoe-shaped cutter is made of YG carbide, with a disc diameter of 20mm and a cutter head height h of 3mm. Eight cutter heads are welded on the cutter disc, and the gap (a-2h) between the two disc horseshoe-shaped cutters is adjusted to 0.2mm.

[0088] Select flake graphite powder with a particle size <8μm, and mix 70% graphite powder, 2% polyacrylate, 2% polyvinyl butyral, 3% ethyl cellulose, 5% p-xylene, 5% methanol, and 13% ethyl acetate by mass percentage to form a uniform black coating with a viscosity of 2600 cP.

[0089] The disc horseshoe-shaped cutter rotates in opposite directions, with the laser-absorbing coating feeding device placed to the side. During the rotation of the disc horseshoe-shaped cutter, the cutting head adheres to the laser-absorbing coating, which is then applied to the interface joint during pre-cutting. The disc horseshoe-shaped cutter pre-cuts the brazing wire. Adjusting the wire feed speed to 5 mm / s and the linear speed of the disc horseshoe-shaped cutter to 51 mm / s, the brazing wire is pre-cut into a pod shape. The length l of a single pre-cut segment is 1 mm, and the diameter change of the brazing wire is 0.2 mm. Black laser-absorbing coating adheres to the diameter change point of the brazing wire.

[0090] Adding an 800W YAG laser generator to the rear end of the brazing wire can melt the wire into a near-spherical brazing wire with a diameter of 1mm. The resulting near-spherical brazing wire products include... Figure 3 As shown.

[0091] Example 3

[0092] The ball is made of 105 copper alloy wire with a wire diameter of 6mm.

[0093] The horseshoe-shaped cutter is made of PCD material, with a disc diameter of 40mm and a cutter head height h of 4mm. Three cutter heads are welded on the cutter disc, and the gap (a-2h) between the two disc horseshoe-shaped cutters is adjusted to 0.8mm.

[0094] Select flake graphite powder with a particle size <6μm, and mix 40% graphite powder, 1% polyacrylate, 2% polyvinyl butyral, 1% polyvinylpyrrolidone, 2% methylcellulose, 2% ethylcellulose, 10% ethyl acetate, 20% dimethyl sulfoxide, and 22% butyl acetate by mass percentage to form a uniform black coating with a viscosity of 2300 cP.

[0095] The disc horseshoe-shaped cutter rotates in opposite directions, with the laser-absorbing coating feeding device placed to the side. During the rotation of the disc horseshoe-shaped cutter, the cutting head adheres to the laser-absorbing coating, which is then applied to the interface joint during pre-cutting. The disc horseshoe-shaped cutter pre-cuts the brazing wire. Adjusting the wire feed speed to 10 mm / s and the linear speed of the disc horseshoe-shaped cutter to 83.73 mm / s, the brazing wire is pre-cut into a pod shape. The length l of a single pre-cut segment is 6 mm, and the diameter change of the brazing wire is 0.8 mm. Black graphite coating adheres to the diameter change point of the brazing wire.

[0096] Adding a YAG laser generator with a power of 1500W to the rear end of the brazing wire can melt the brazing wire into a near-spherical brazing wire with a diameter of 6mm.

[0097] Comparative Example 1

[0098] Comparative Example 1 is similar to Example 1, except that: a disc horseshoe-shaped cutter is used directly to cut the brazing filler metal BAg72Cu alloy wire without laser melting. When only cutting is used, the cutter needs to be adjusted to avoid collision between the upper and lower cutters. Servo precision cutting is used to ensure cutting accuracy. Other equipment parameters are the same as in Example 1. The particle fracture obtained by cutting in this comparative example is flat, but spherical cutting cannot be guaranteed.

[0099] Comparative Example 2

[0100] Comparative Example 2 is similar to Example 1, except that the BAg72Cu alloy wire was not pre-cut. Instead, laser-absorbing coating was directly applied to the cut area, and laser cutting was used to melt through the coating point. The laser power needed to reach 4000W to melt through. The particles obtained in this comparative example without pre-cutting still had a flat cross-section, and spherical particles could not be sheared.

[0101] Comparative Example 3

[0102] Comparative Example 3 is similar to Example 1, except that: the BAg72Cu alloy wire was not pre-cut, the entire outer surface of the wire was coated with a laser-absorbing coating, and the spherical wire was prepared by laser droplet formation. The required laser power is at least 9000W to melt the wire. The melting process requires a large laser power and it is difficult to control the size of the droplets.

[0103] Comparative Example 4

[0104] Comparative Example 4 is similar to Example 1, except that the BAg72Cu alloy wire was not pre-cut and was not coated with laser-absorbing coating. The spherical solder was prepared directly by laser droplet forming method. The required laser power is at least 18000W to melt it. The melting process requires a large laser power and it is difficult to control the size of the droplets.

[0105] Comparative Example 5

[0106] Comparative Example 5 uses a traditional method to cut a 3.2mm diameter BAg72Cu alloy wire into cylindrical segments with a length of 3.2mm, and grind them into spherical brazing filler metal with a diameter of 3mm.

[0107] Test case

[0108] (1) The material utilization rates of Examples 1-3 and Comparative Examples 3-5 were tested respectively, and the test results are shown in Table 1.

[0109] Table 1

[0110] sample Material utilization rate Example 1 99.97％ Example 2 99.68％ Example 3 99.35％ Comparative Example 3 98.56％ Comparative Example 4 97.63％ Comparative Example 5 41.20％

[0111] As can be seen from the data in Table 1, the traditional grinding and ball-making method in Comparative Example 5 has low material utilization and a lot of material waste, while the method of the present invention has high material utilization and virtually no loss.

[0112] (2) Ten samples were randomly selected from the near-spherical particle brazing filler metals prepared in Examples 1-3 and Comparative Examples 3-5, respectively, and the diameter of the near-spherical particle brazing filler metals was tested. The test results are shown in Table 2.

[0113] Table 2

[0114]

[0115]

[0116] As can be seen from the data in Tables 1 and 2, the near-spherical brazing filler metal prepared by the method of the present invention has high material utilization, high dimensional accuracy, and good uniformity. In contrast, although the laser droplet forming method also has a high material utilization, the droplet size is difficult to control, resulting in low dimensional accuracy and poor uniformity of the product. Although the traditional grinding forming method has good dimensional uniformity, it has very low material utilization, large waste, and high cost. Therefore, the method of the present invention has a better overall effect.

[0117] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for processing near-spherical granular brazing filler metal, characterized in that, Includes the following steps: The brazing wire is pre-cut into a pod shape using two symmetrically arranged, adjustable horseshoe-shaped cutters (1) about the brazing wire. The horseshoe-shaped cutters (1) include a disc (11) and multiple horseshoe-shaped cutters (12) fixed on the disc (11). The multiple horseshoe-shaped cutters (12) are evenly distributed around the circumference of the disc (11). The laser-absorbing coating is supplied to the horseshoe-shaped cutters (12) using a laser-absorbing coating feeding device (2). The brazing wire is pre-cut by the horseshoe-shaped cutters (12) and the laser-absorbing coating is applied to the cut joint formed by the pre-cutting. Then, the cut joint coated with the laser-absorbing coating is melted by a laser to obtain the near-spherical brazing wire particles. The gap 'a' between the two disks satisfies the following conditions: a≥d, 0.2mm≤a-2h<d / 2, where d is the diameter of the brazing wire and h is the height of the horseshoe-shaped cutter head; The rotational linear velocity V1 of the disc horseshoe-shaped hob and the wire feed speed V2 satisfy the following relationship: V2 = l NV1 / [π(D+2h)], where, l N is the length of a single pre-cut segment, N is the number of horseshoe-shaped cutters on a single disk, and D is the diameter of the disk; The brazing wire includes copper alloy wire or silver alloy wire; The laser absorbing coating comprises the following components by weight percentage: 40%-70% graphite powder, 4%-8% high molecular organic material, 2%-5% thickener and 20%-52% solvent.

2. The processing method for near-spherical particle brazing filler metal according to claim 1, characterized in that, It contains at least one of the following features: (1) The wire diameter and the length of a single pre-cut segment of the brazing wire are both matched with the diameter of the near-spherical brazing filler metal; (2) The diameter of the cut connection is 0.2mm-d / 2, where d is the wire diameter of the brazing wire.

3. The method for processing near-spherical particle brazing filler metal according to claim 1, characterized in that, It contains at least one of the following features: (1) The particle size of the graphite powder is less than 10 μm; (2) The polymeric organic material includes at least one of polyacrylate, polyvinyl butyral, and polyvinylpyrrolidone; (3) The thickener includes methylcellulose and / or ethylcellulose; (4) The solvent includes at least one of trichloroethylene, dichloroethylene, carbon tetrachloride, toluene, p-xylene, ethyl acetate, dimethyl sulfoxide, butyl acetate, methanol, ethanol, chloroform, and acetone.

4. The method for processing near-spherical particle brazing filler metal according to claim 1, characterized in that, The power of the laser is 500-5000W.

5. A near-spherical granular brazing filler metal, characterized in that, It is prepared by the processing method of the near-spherical particle brazing filler metal according to any one of claims 1-4.

6. A processing apparatus for near-spherical brazing filler metal particles, characterized in that, A method for processing near-spherical solder particles according to any one of claims 1-4, comprising: Two symmetrically arranged, adjustable horseshoe-shaped disc cutters are used to pre-cut the brazing wire passing through their gap. The horseshoe-shaped disc cutters include a disc and a plurality of horseshoe-shaped cutters fixed on the disc. The plurality of horseshoe-shaped cutters are evenly distributed around the circumference of the disc. A laser-absorbing coating feeding device is used to supply laser-absorbing coating to the horseshoe-shaped cutter; A laser generator, located downstream of the disc horseshoe-shaped cutter, is used to melt the pre-cut portion of the brazing wire; The receiving bin is used to collect near-spherical brazing filler metal particles.

7. The processing apparatus for near-spherical particle brazing filler metal according to claim 6, characterized in that, The laser-absorbing coating feeding device includes a coating box and laser-absorbing coating inside the coating box. The side wall of the coating box near the horseshoe-shaped cutter is made of a flexible porous material. When the horseshoe-shaped cutter rotates, it passes through the coating box and comes into contact with the flexible porous material to pick up the laser-absorbing coating. When pre-cutting the brazing wire, the laser-absorbing coating is applied to the cut joint of the brazing wire.

8. The processing apparatus for near-spherical particle brazing filler metal according to claim 7, characterized in that, The flexible porous material includes at least one of sponge, cotton, and absorbent paper; And / or, the viscosity of the laser-absorbing coating is 2000-5000 cP.

9. The processing apparatus for near-spherical brazing filler metal particles according to claim 6, characterized in that, It contains at least one of the following features: (1) The horseshoe-shaped cutter is made of any one of cemented carbide, high-speed steel, or superhard material; (2) The laser generator is a YAG laser generator or a semiconductor laser generator.

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