Metal welding ring and preparation method thereof

Abstract

The invention discloses a metal welding ring and a preparation method thereof.The metal welding ring is provided with an annular body, the annular body is of a closed structure, and a plurality of holes are formed in the annular body so that an expansion space can be provided for the annular body in the heating process of the annular body. The closed annular structure of the metal welding ring can reduce the internal stress of the metal welding ring, and a plurality of pores are formed in the metal welding ring, so that the metal welding ring can expand towards the positions of the pores when being heated and deformed in the welding process. The stress of the welding ring can be reduced and a buffer and dispersion space is provided for the thermal expansion stress of the welding ring through the closed annular structure and internal pores, so that the condition of ring flying of the metal welding ring is avoided. The distance between the upper end and the lower end of the radial section of the annular body is gradually decreased or increased in the direction away from the center of the annular body, the molten welding rings can be guided to be evenly distributed and extend on the surface of a to-be-welded connector, gaps of the connector are fully filled, and the welding effect is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding materials, and in particular relates to a metal welding ring and a preparation method thereof. Background Art

[0002] In modern industrial production, metal welding rings are widely used for precision connections due to their precise dimensions and ease of automated operation. Currently, the mainstream method for manufacturing metal welding rings is through extrusion and drawing. However, this process results in significant internal stress within the metal welding rings. When these metal welding rings with internal stress are heated during welding or brazing, especially during rapid temperature increases, the internal residual stress is violently released. This uneven and violent stress release can cause the welding ring to deform or even momentarily bounce out of its intended position before or just after melting, a phenomenon known as "flying rings." This prevents welding at the designated location, wastes material, and affects welding accuracy.

[0003] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0004] The object of the present invention is to provide a metal welding ring with lower internal stress, which can avoid flying rings and improve welding accuracy.

[0005] In order to achieve the above-mentioned purpose, a technical solution provided by a specific embodiment of the present invention is as follows: a metal welding ring, which has an annular body, the annular body is a closed structure and has multiple pores inside the annular body to provide expansion space for the annular body during the heating process of the annular body.

[0006] In one or more embodiments of the present invention, the radial cross-section of the annular body is circular, semicircular, D-shaped, trapezoidal or triangular.

[0007] In one or more embodiments of the present invention, the distance between the upper and lower ends of the radial cross section of the annular body gradually decreases in a direction away from the center of the annular body.

[0008] In one or more embodiments of the present invention, the distance between the upper and lower ends of the radial cross section of the annular body gradually increases in a direction away from the center of the annular body.

[0009] Compared to existing techniques, the closed ring structure of the metal welding ring of the present invention reduces internal stress within the ring and features multiple internal pores, allowing the ring to expand toward the locations of the pores when deformed by heat during welding. The closed ring structure and internal pores reduce stress within the ring and provide a buffer and dispersion space for thermal expansion stress, preventing the ring from "flying." Furthermore, the distance between the upper and lower ends of the radial cross-section of the ring body gradually decreases or increases as it moves away from the center of the ring body. This guides the molten ring to spread evenly across the surface of the joint to be welded, fully filling the gaps within the joint and improving the welding effect.

[0010] The technical solution provided by another specific embodiment of the present invention is as follows: A method for preparing a metal welding ring includes: uniformly mixing welding powder, molding material and placeholder to obtain a first mixed powder; placing the first mixed powder into an annular mold and performing compression molding in a molding machine to obtain an annular green body; transferring the annular green body to a sintering furnace, heating the annular green body to degrease the annular green body and keeping it warm; continuing to heat the body so that the placeholder is completely decomposed to form pores in the annular green body and sintering it, and cooling it to room temperature under a protective atmosphere to obtain a metal welding ring.

[0011] In one or more embodiments of the present invention, the average particle size D50 of the welding powder is between 10 μm and 100 μm; and / or the welding powder is selected from one of electrolytic copper powder, phosphor copper powder, nickel powder, boron powder, silicon powder, and chromium powder; and / or the mass percentage of the welding powder is between 75% wt and 94.5% wt.

[0012] In one or more embodiments of the present invention, the molding material is selected from one or more of zinc stearate, polyvinyl alcohol, polyethylene glycol and polystyrene; and / or the mass percentage of the molding material is between 0.5% wt and 5% wt.

[0013] In one or more embodiments of the present invention, the spacer is selected from one or more of PMMA and PS; and / or the mass percentage of the spacer is between 5% wt and 20% wt.

[0014] In one or more embodiments of the present invention, the decomposition temperature of the spacer is lower than the sintering temperature of the solder powder.

[0015] In one or more embodiments of the present invention, the method for preparing the metal welding ring further includes: re-pressing and cleaning the sintered metal welding ring.

[0016] Compared to existing technologies, the present invention's method for preparing a metal welding ring utilizes a molding process, resulting in a closed metal welding ring structure and significantly reducing internal stress within the ring. Furthermore, by adding a spacer to the raw materials, which decomposes during the sintering stage, pores are created within the metal welding ring, providing space for thermal expansion to buffer and disperse, rather than acting solely on the contact surface between the metal welding ring and the workpiece. This mitigates the problem of metal welding ring displacement during welding and avoids the "flying ring" phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 is a three-dimensional diagram of a metal welding ring in one embodiment of the present invention;

[0019] Figure 2 Schematic diagram of a metal welding ring along the AA axis with a radial cross section in a "D" shape according to one embodiment of the present invention;

[0020] Figure 3 Schematic diagram of a metal welding ring along the AA axis with a triangular radial cross section in one embodiment of the present invention;

[0021] Figure 4 FIG. 1 is a schematic diagram of a metal welding ring along the AA axis in an embodiment of the present invention, wherein the radial cross-section is a trapezoid.

[0022] Description of main reference numerals:

[0023] 1- annular body, 2- pores. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0025] like Figure 1As shown, a metal welding ring according to an embodiment of the present invention comprises an annular body 1. The annular body 1 is a closed structure and has a plurality of pores 2 therein to provide expansion space for the annular body 1 during heating.

[0026] In this embodiment, compared to the open or notched weld rings produced by traditional drawing processes, this metal weld ring is integrally formed, forming a closed ring structure, which reduces internal stress within the metal weld ring. Furthermore, the annular body 1 has multiple pores 2 within it. This allows the metal weld ring to expand toward the locations of these pores 2 when thermally deformed during welding. The thermal expansion stress is then buffered and dispersed by these pores 2 distributed within the annular body 1, thus preventing the metal weld ring from "flying rings."

[0027] In one embodiment, the radial cross-section of the annular body 1 can be circular, semicircular, D-shaped, trapezoidal or triangular, but is not limited to the aforementioned shapes and can be adjusted or selected according to actual use requirements.

[0028] Optionally, the distance between the upper and lower ends of the radial cross-section of the annular body 1 gradually decreases in the direction away from the center of the annular body 1; or, the distance between the upper and lower ends of the radial cross-section of the annular body 1 gradually increases in the direction away from the center of the annular body 1.

[0029] like Figure 2 As shown, taking the radial cross section of the annular body 1 as a D-shape as an example, the arc side of the cross section can be toward the center of the annular body 1 (i.e. Figure 2 The annular body 1 may be convex in the direction opposite to the arrow B), or may be convex in the direction away from the center of the annular body 1 (i.e. Figure 2 (In the direction indicated by arrow B in the middle). When the arc side of the cross section bulges toward the center of annular body 1, the distance between the upper and lower ends of the radial cross section of annular body 1 gradually increases in the direction away from the center of annular body 1. When the arc side of the cross section bulges away from the center of annular body 1, the distance between the upper and lower ends of the radial cross section of annular body 1 gradually decreases in the direction away from the center of annular body 1. Preferably, the arc side of the cross section bulges away from the center of annular body 1 so that the molten metal weld ring will more naturally spread outward along the surface of annular body 1 on the arc side, thereby forming a full, beautiful, and easy-to-inspect weld.

[0030] like Figure 3 As shown, when the radial cross section of the annular body 1 is a triangle, the sharp corner of the triangle can be oriented toward the center of the annular body 1 (i.e. Figure 3Preferably, when the sharp corner is raised away from the center of the annular body 1, the molten solder ring will more naturally spread and fill outward along the sharp corner under the capillary action, which can also effectively guide the flow of solder to form a full and uniform external weld.

[0031] like Figure 4 As shown, when the radial cross section of the annular body 1 is a trapezoid, the top of the trapezoid can be toward the center of the annular body 1 or away from the center of the annular body 1 (i.e. Figure 4 In the opposite direction of arrow B), preferably, the top of the trapezoid is away from the center of the annular body 1. Such a setting can better utilize the capillary effect to effectively guide the molten welding ring to the gap area that needs to be filled, ensuring sufficient filling of the inside of the joint to be welded.

[0032] In summary, the closed annular structure of the metal welding ring can reduce its internal stress and has multiple pores 2 inside, allowing the metal welding ring to expand toward the location of the pores 2 when it is thermally deformed during welding. The closed annular structure and internal pores 2 can reduce the stress of the welding ring and provide a buffer and dispersion space for the thermal expansion stress of the welding ring, thereby preventing the metal welding ring from "flying ring" from occurring. Furthermore, the distance between the upper and lower ends of the radial cross-section of the annular body 1 gradually decreases or increases in the direction away from the center of the annular body 1, which can guide the molten welding ring to be evenly distributed and extended on the surface of the joint to be welded, fully filling the gaps in the joint and improving the welding effect.

[0033] A method for preparing a metal welding ring in another embodiment of the present invention includes steps S1 to S4.

[0034] Step S1: uniformly mix welding powder, molding material and placeholder to obtain a first mixed powder.

[0035] Specifically, in step S1, welding powder, molding material, and placeholder are placed in a mixer and mixed to obtain a first mixed powder. The mixer can be a V-type mixer, a double-cone mixer, a planetary mixer, a forced mixer, or a ball mill. These mixers provide an efficient mixing environment for the raw materials, ensuring thorough mixing of the welding powder, molding material, and placeholder while avoiding over-grinding and powder agglomeration.

[0036] Preferably, the welding powder, molding material and placeholder are mixed in dry air or an inert atmosphere with low humidity to prevent the welding powder, such as copper powder, from absorbing moisture or undergoing preliminary oxidation during the mixing process.

[0037] In one embodiment, the average particle size D50 of the welding powder is between 10 μm and 100 μm. Preferably, the average particle size D50 is between 30 μm and 80 μm. An average particle size of welding powder below 10 μm results in poor powder flowability and difficulty agglomerating during subsequent pressing. An average particle size greater than 100 μm makes subsequent sintering and densification difficult, requiring longer sintering times or higher sintering temperatures.

[0038] The welding powder is selected from one or more of electrolytic copper powder, phosphor copper powder and nickel powder.

[0039] The molding material is selected from one or more of zinc stearate, polyvinyl alcohol, polyethylene glycol, and polystyrene, with the mass percentage of the molding material ranging from 0.5% to 5% by weight. The molding material acts as a lubricant during the molding process, reducing friction between powder particles and between the powder and the mold wall, thereby lowering the required molding pressure, improving the uniformity of the green body density, and ensuring the strength of the green body.

[0040] The spacer is selected from one or more of PMMA and PS, and the decomposition temperature of the spacer is lower than the sintering temperature of the solder powder. The mass percentage of the spacer is between 5% wt and 20% wt, preferably between 7% wt and 12% wt.

[0041] Step S2: placing the first mixed powder into an annular mold and performing compression molding in a molding machine to obtain an annular green compact.

[0042] Specifically, in step S2, the first mixed powder is fed into an annular mold in a hydraulic press or a mechanical press and pressed under a pressure of 400-800 MPa for 10-30 seconds, and then demolded to obtain an annular green body.

[0043] Among them, the annular mold is a cemented carbide grinding tool with high precision and high wear resistance. The first mixed powder is subjected to 400-800MPa in the annular mold and is pressed and maintained for 10-30s. This pressure range can ensure that the green body obtains sufficient density and strength, while avoiding excessive wear of the mold and cracking of the green body due to excessive pressure. A sufficiently long holding time is conducive to the plastic deformation and rearrangement of the powder particles, reducing elastic recovery, and further improving the density and uniformity of the green body. When demolding, the mold should have a good demolding mechanism, and a small amount of release agent such as graphite emulsion can be used to coat the mold surface to prevent the green body from sticking and being damaged.

[0044] Step S3: transferring the annular green body to a sintering furnace, heating the annular green body to perform degreasing treatment and keeping the temperature.

[0045] Specifically, in step S3, the green body is transferred to a pusher furnace or a mesh belt furnace, and a reducing gas, such as high-purity hydrogen or ammonia, is introduced into the furnace, and then the temperature is slowly increased to 300-600°C at a rate of 2-5°C / min, and then kept warm for 45-120 minutes. The flow rate of the reducing gas can be between 100mL / min-5L / min for experimental equipment. For large-scale industrial reduction furnaces, the flow rate of the reducing gas can be between 5m 3 / h-50m 3 / h.

[0046] During this step, adding reducing gas to the sintering furnace effectively reduces oxides on the surface of the solder powder, preventing further oxidation during sintering and promoting densification of the solder powder within the green body. During the degreasing phase, temperature control, ensuring a high flow rate of reducing atmosphere within the furnace, and efficient exhaust ensure that the molded material is fully decomposed and promptly and thoroughly discharged from the furnace, preventing any residual molded material from affecting the final performance of the metal weld ring.

[0047] Step S4: continue to increase the temperature so that the placeholder is completely decomposed and pores are formed in the annular green body and sintered at the same time, and then cool to room temperature under a protective atmosphere to obtain a metal welding ring.

[0048] Specifically, in step S4, the temperature is rapidly raised to 800°C-1150°C at a rate of 5-10°C / minute at the degreasing temperature for sintering, and during the heating process, the placeholder is completely decomposed to form pores in the annular green body. After reaching the sintering temperature, it is kept warm for 45-120 minutes, and then rapidly cooled to room temperature by furnace cooling or water cooling under a protective atmosphere to obtain a metal welding ring.

[0049] By controlling the sintering temperature, the metal atoms in the solder powder receive sufficient diffusion energy, promoting grain growth and pore shrinkage. Heat preservation ensures complete densification of the solder powder, resulting in the metal solder ring achieving the desired porosity and mechanical properties. Simultaneously, rapid cooling prevents high-temperature oxidation of the metal solder ring, effectively controlling its microstructure.

[0050] In this step, the sintering temperature also needs to ensure that it is greater than the decomposition temperature of the placeholder, so that the placeholder can be completely removed before sintering or in the early stage of sintering without residue, thereby forming the required pores inside the metal welding ring and meeting the required porosity of the metal welding ring.

[0051] In one embodiment, the method for preparing the metal welding ring further includes step S5.

[0052] Step S5: re-pressing and cleaning the sintered metal welding ring.

[0053] Specifically, in step S5, the sintered metal welding ring is re-pressed at a pressure of 600-800 MPa. The cleaning step involves lightly cleaning or polishing the metal welding ring to remove any oxide layer or contaminants on its surface, facilitating subsequent welding. For example, an acid pickling and passivation treatment can be performed to improve the corrosion resistance of the metal welding ring. Furthermore, the re-pressed metal welding ring can be annealed in a protective atmosphere at 400°C-500°C for 20-40 minutes to eliminate the work hardening and residual stress introduced by the re-pressing and restore the plasticity and toughness of the metal welding ring.

[0054] Taking a pure copper welding ring as an example, the specific preparation method of the metal welding ring is as follows.

[0055] Step S1: Electrolytic copper powder, zinc stearate, and PMMA with a purity of 99.9% or higher are selected, with the mass percentages being 90% by weight, 0.5% by weight, and 9.5% by weight, respectively. The electrolytic copper powder, zinc stearate, and PMMA are mixed in a V-type mixer and nitrogen is introduced to obtain a first mixed powder.

[0056] Step S2: The first mixed powder is fed into a hydraulic press and a WC-Co alloy mold is used to apply a pressing pressure of 500 MPa and hold the pressure for seconds to obtain a green body.

[0057] Step S3: The green body is transferred into a pusher furnace, hydrogen is introduced, and the green body is slowly heated to 400° C. at a rate of 5° C. / min and kept at this temperature for 90 minutes, and the decomposition products of zinc stearate are promptly discharged from the furnace.

[0058] Step S4: heating the green body to 1000° C. at a rate of 10° C. / min, and then keeping the temperature for 120 minutes to obtain a metal welding ring.

[0059] Step S5: re-pressing the metal welding ring at a pressure of 700 MPa and keeping it at 450° C. for 30 minutes, and then cleaning it to obtain a cleaned metal welding ring.

[0060] In summary, the present method for preparing the metal welding ring utilizes a molding process, which can achieve a closed metal welding ring structure and substantially reduce the internal stress of the metal welding ring. Furthermore, by adding a spacer to the raw material and allowing the spacer to decompose during the sintering stage, pores are left within the metal welding ring, providing space for buffering and dispersing the thermal expansion of the metal welding ring, rather than acting entirely on the contact surface between the metal welding ring and the workpiece. This alleviates the problem of metal welding ring displacement during welding and avoids the "flying ring" phenomenon of the metal welding ring.

[0061] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0062] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A metal welding ring, characterized in that: The invention has an annular body, which is a closed structure and has a plurality of pores inside the annular body to provide expansion space for the annular body when the annular body is heated.

2. The metal welding ring according to claim 1, characterized in that: The radial cross section of the annular body is circular, semicircular, D-shaped, trapezoidal or triangular.

3. The metal welding ring according to claim 2, characterized in that: The distance between the upper and lower ends of the radial cross section of the annular body gradually decreases in a direction away from the center of the annular body.

4. The metal welding ring according to claim 2, characterized in that: The distance between the upper and lower ends of the radial cross section of the annular body gradually increases in a direction away from the center of the annular body.

5. A method for preparing a metal welding ring, characterized in that: include: uniformly mixing welding powder, molding material and placeholder to obtain a first mixed powder; placing the first mixed powder into an annular mold and performing compression molding in a molding machine to obtain an annular green compact; Transferring the annular green compact to a sintering furnace, heating the annular green compact to perform degreasing treatment and keeping the temperature; and The temperature is continued to be raised so that the spacer is completely decomposed to form pores in the annular green body and sintered, and then cooled to room temperature under a protective atmosphere to obtain a metal welding ring.

6. The method for preparing a metal welding ring according to claim 5, characterized in that: The average particle size D50 of the welding powder is between 10 μm and 100 μm; and / or the welding powder is selected from one of electrolytic copper powder, phosphor copper powder, nickel powder, boron powder, silicon powder, and chromium powder; and / or the mass percentage of the welding powder is between 75% wt and 94.5% wt.

7. The method for preparing a metal welding ring according to claim 5, characterized in that: The molding material is selected from one or more of zinc stearate, polyvinyl alcohol, polyethylene glycol and polystyrene; and / or the mass percentage of the molding material is between 0.5%wt and 5%wt.

8. The method for preparing a metal welding ring according to claim 5, wherein: The spacer is selected from one or more of PMMA and PS; and / or the mass percentage of the spacer is between 5% wt and 20% wt.

9. The method for preparing a metal welding ring according to claim 5, wherein: The decomposition temperature of the spacer is lower than the sintering temperature of the solder powder.

10. The method for preparing a metal welding ring according to claim 5, characterized in that: Also includes: The sintered metal welding ring is re-pressed and cleaned.

Images