A high-frequency welding method for transformer leads

Abstract

The present invention belongs to the field of transformer lead connection, and specifically discloses a high-frequency welding method for transformer leads, including the following steps: S1: stripping the insulated copper stranded wire to be welded, and rounding the ends of the insulated copper stranded wire and the flat copper wire; S2: inserting the portions of the insulated copper stranded wire and the flat copper wire to be welded into a connecting sleeve, adding solder to the connection between the insulated copper stranded wire and the flat copper wire, and heating the connecting sleeve using a high-frequency welding inductor; S3: cooling the connecting sleeve after heating; S4: insulating the connecting sleeve. The technical solution provided by the present invention has the following advantages over the prior art: the present invention welds the insulated copper stranded wire and the flat copper wire through high-frequency welding, and has a fast welding speed, strong current-carrying capacity, a small space required for the operating area, and a smooth and round electrode shape. The use of a silver welding rod as a solder guide for the solder liquid improves the filling rate of the silver solder liquid during the welding process.

Description

Technical Field

[0001] The invention belongs to the technical field of transformer leads, and in particular relates to a high-frequency welding method for transformer leads. Background Art

[0002] The existing technology for connecting transformer leads internally often uses phosphor copper welding. This results in poor electrode shape, concentrated electric fields, difficult-to-clean oxide layers after welding, and a high risk of cold joints. This ultimately results in multiple, thick shielding layers at the connection point, large insulation dimensions, and poor heat dissipation. Later, cold pressing was used. While this method addressed the hazards and pollution associated with using a fire source on the transformer, its electrode shape and final dimensions required a significant amount of space.

[0003] High-frequency welding primarily utilizes the skin effect of high-frequency current to concentrate high-frequency electrical energy on the surface of the weldment. It also utilizes the proximity effect to control the location and range of the high-frequency current flow path. When the high-frequency current is required to be concentrated on a specific part of the weldment, the two metal materials can be joined by forming a current loop between the conductor and the weldment and placing the conductor close to that part of the weldment, forming adjacent conductors. High-frequency welding results in a small heat-affected zone and rapid heating, significantly improving welding speed and weld quality.

[0004] If high-frequency welding is used to weld the leads of the transformer, although it can avoid the problems of large insulation size and local overheating caused by cold welding in the existing technology, due to the influence of the surface flatness and edge straightness of the connecting sleeve, there are currently insurmountable problems such as high burrs inside and outside the weld, poor electrode shape, copper foam generated by filing and contamination of the winding. Therefore, there is currently no precedent for using high-frequency welding method to weld the leads. Summary of the Invention

[0005] The invention provides a high-frequency welding method for transformer leads, which is used to solve the current problems of high burrs inside and outside the weld, poor electrode shape, and copper foam generated by filing and contaminating the winding.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: a high-frequency welding method for transformer leads, which includes the following steps:

[0007] S1: Strip the insulated copper stranded wire to be welded, and round the ends of the insulated copper stranded wire and the flat copper wire;

[0008] S2: inserting the insulated copper stranded wire and the flat copper wire to be welded into a connecting sleeve, adding solder to the connection between the insulated copper stranded wire and the flat copper wire, and heating the connecting sleeve using a high-frequency welding inductor;

[0009] S3: After the heating is completed, the connecting sleeve is cooled;

[0010] S4: Insulate the connecting sleeve.

[0011] In a preferred embodiment of the present invention, the wire stripping in step S1 is performed by using a step-by-step cutting method to strip the insulation layer of the insulated copper stranded wire into a cone shape, and the length of the cone is at least ten times the thickness of the insulation layer.

[0012] In a preferred embodiment of the present invention, in step S1, when a paint film is formed on the rectangular copper wire, the rectangular copper wire is first stripped of the paint by induction heating.

[0013] In a preferred embodiment of the present invention, in step S1, copper tape is wrapped around the ends of the insulated copper stranded wires and / or the flat copper wires.

[0014] In a preferred embodiment of the present invention, in step S2: a chromium layer or a nickel layer with a thickness of 18-22 μm is provided on the surface of the connecting sleeve.

[0015] In a preferred embodiment of the present invention, in step S2: a feeding hole is provided on the connecting sleeve, and the feeding hole is used to place a silver welding rod between the insulated copper stranded wire and the flat copper wire.

[0016] In a preferred embodiment of the present invention, in step S2, the position of the feed hole corresponds to the connection position of the insulated copper stranded wire and the flat copper wire.

[0017] In a preferred embodiment of the present invention, in step S2: the center of the feed hole is located at the axial midpoint of the connecting sleeve.

[0018] In a preferred embodiment of the present invention, in step S2: the axial length of the feed hole along the connecting sleeve is 1.8-2.2 mm, the circumferential length of the feed hole along the connecting sleeve is 7.5-8.5 mm, the inner diameter of the connecting sleeve is 9.8-28.1 mm, the outer diameter of the connecting sleeve is 14.0-33.3 mm, the single-side wall thickness of the connecting sleeve is 2.05-2.5 mm, and the length of the connecting sleeve is 48-70 mm.

[0019] In a preferred embodiment of the present invention, in step S2: a U-shaped inductor is used to heat the connecting sleeve from both ends toward the middle.

[0020] In a preferred embodiment of the present invention, in step S2: during the heating process, when the temperature of the connecting sleeve is higher than the melting point of the silver solder rod, the silver solder rod is added to the inside of the connecting sleeve through the feed hole; when solder overflows from both ends of the connecting sleeve and the feed hole, the addition of the silver solder rod is stopped.

[0021] In a preferred embodiment of the present invention, in step S2: after stopping the feeding, the connecting sleeve is repeatedly heated 2 to 3 times.

[0022] In a preferred embodiment of the present invention, in step S3, asbestos cloth soaked in 94%-96% alcohol is used to cool the connecting sleeve.

[0023] In a preferred embodiment of the present invention, in step S4: before the insulation treatment, the oxide layer and foreign matter on the connecting sleeve and the welding point are removed.

[0024] In a preferred embodiment of the present invention, step S4 specifically includes: wrapping the connecting sleeve with at least one layer of semi-conductive paper, and then wrapping the connecting sleeve with at least two layers of crepe paper, wherein the crepe paper is crepe paper stretched 70% to 90%.

[0025] The technical solution provided by the present invention offers the following advantages over existing technologies: The present invention utilizes high-frequency welding to weld insulated copper strands and flat copper wires, resulting in high welding speeds, strong current-carrying capacity, a small operating area, and smooth, rounded electrodes. The use of a silver welding rod as a guide for the soldering fluid improves the silver soldering fluid filling rate during the welding process. The present invention also offers advantages such as ease of operation, easy temperature control, high welding speeds, and smooth, no-smear welds. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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 of the present invention. For ordinary technicians in this field, without paying any creative work, they can also obtain drawings of other embodiments based on these drawings.

[0027] Figure 1 Yes; a high-frequency welding method for transformer leads described in one embodiment of the present invention.

[0028] As shown in the figure: 10-insulated copper stranded wire, 20-flat copper wire, 30-connecting sleeve, 301-feed hole, 40-insulation layer, 50-insulation part. DETAILED DESCRIPTION

[0029] For ease of understanding, the high-frequency welding method for transformer leads is described below in conjunction with embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0030] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations and positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0032] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0033] The present invention discloses a high frequency welding method for transformer leads, referring to Figure 1 As shown, in the present invention, the insulated copper strands 10 and the flat copper wires 20 in the transformer are welded by high-frequency welding, which includes the following steps.

[0034] 1. Strip the wire.

[0035] The insulating layer 40 on the insulated copper stranded wire 10 is stripped by a step-by-step cutting method, exposing about 100 mm of the insulated copper stranded wire 10. During stripping, the insulating layer 40 on the insulated copper stranded wire 10 is tapered, and the length of the tapered layer is at least ten times the thickness of the insulating layer 40.

[0036] In this step, if the rectangular copper wire 20 is coated with a paint film, the paint needs to be removed in advance because the paint surface will affect the quality of high-frequency welding. In the present invention, the rectangular copper wire 20 is removed by high-frequency induction heating.

[0037] 2. Repair the lines.

[0038] The insulated copper stranded wire 10 and the flat copper wire 20 are rounded flush with each other.

[0039] In one embodiment of the present invention, copper tape is wrapped around the ends of the insulated copper stranded wire 10 and the flat copper wire 20. Specifically, at the welding end, the ends are first rounded using a tool. This may result in a deviation between the outer diameter of the rounded end and the inner diameter of the welding sleeve. To reduce this deviation, the rounded end is finally wrapped with copper tape to bring the outer diameter of the wound end closer to the inner diameter of the welding sleeve. This reduces the amount of silver solder used and increases or even ensures welding speed. This ensures that the insulated copper stranded wire 10 and the flat copper wire 20 can be directly connected, and after the welding area is insulated, the outer insulation limit size can be controlled.

[0040] 3. Process the connecting sleeve.

[0041] A connecting sleeve 30 having a size matching that of the insulated copper stranded wire 10 and the flat copper wire 20 is selected, and a chromium layer or a nickel layer having a thickness of 18-22 μm is plated on the surface of the connecting sleeve 30 to enable the connecting sleeve 30 to withstand high temperatures.

[0042] In order to adapt to different sizes (such as 50, 70, 95, 120, 150, 180, 240, 300, 400, 500mm 2 ) is welded to the flat copper wire 20 and the insulated copper stranded wire 10. The inner diameter of the connecting sleeve 30 is usually 9.8-28.1mm, the outer diameter is usually 14.0-33.3mm, the single-side wall thickness is 2.05-2.5mm, and the length is 48-70mm.

[0043] 4. Punch through the material hole.

[0044] A punching machine is used to punch a feed hole 301 in the middle of the connecting sleeve 30, and the processed copper insulated copper stranded wire 10 and the flat copper wire 20 to be welded are inserted into the connecting sleeve 30; then a silver welding rod is placed between the insulated copper stranded wire 10 and the flat copper wire 20 as a filler through the feed hole 301.

[0045] During this step, a feed hole 301 is defined in the center of the connecting sleeve 30. The hole is 2 mm long and 8 mm circumferentially. The solder at the feed hole 301 is squeezed into the inner diameter of the connecting sleeve 30, acting as a stop and reference point when the insulated copper stranded wire 10 and the flat copper wire 20 are inserted from both ends of the connecting sleeve 30.

[0046] The present invention uses a silver soldering rod, which can melt and guide the silver soldering liquid. The cross-sectional size of the silver soldering rod used in the present invention is 2mm×5mm to ensure that the silver soldering rod can move freely in and out of the feed hole 301.

[0047] 5. Heating.

[0048] Specifically, the present invention uses a U-shaped inductor to first heat one end of the connecting sleeve 30, then heat the other end of the connecting sleeve 30, and finally heat the middle part of the connecting sleeve 30. This facilitates the melting and flow of the silver solder rod, and ultimately makes the solder liquid in the sleeve evenly distributed and solidified.

[0049] During the heating process, when the color of the connecting sleeve 30 turns red, silver solder is added to the interior of the connecting sleeve 30 through the feed hole 301 at a uniform rate. When the silver solder overflows from both ends of the connecting sleeve 30 and the feed hole 301 in a liquid state, the addition of silver solder is stopped. By observing whether the solder overflows, it can be determined whether the solder inside the connecting sleeve 30 is saturated. Ensuring the solder is saturated reduces the probability and risk of cold solder joints.

[0050] After stopping the feeding, the connecting sleeve is heated repeatedly 2 to 3 times to discharge the residual gas in the connecting sleeve 30.

[0051] 6. Cool down.

[0052] After the heating is completed, the connecting sleeve 30 is cooled using asbestos cloth soaked in 94%-96% alcohol to reduce the amount of copper oxide remaining on the rectangular copper wire 20 .

[0053] 7. Post-processing.

[0054] The oxide layer and foreign matter on the connecting sleeve 30 and the welding point are removed and insulation treatment is performed.

[0055] An insulating layer 50 is provided on the connecting sleeve 30. Specifically, the insulating layer 50 comprises two layers of semi-conductive paper wrapped in a half-fold manner, with the semi-conductive paper extending within 10 mm from both ends of the sleeve. Crepe paper with a width of less than 40 mm is used to cover the connecting area. To ensure that the crepe paper wrapping process is tight and not loose, the crepe paper is stretched by 70% to 90% in the present invention. At least two layers of stretched crepe paper are then wrapped in a half-fold manner on the connecting sleeve 30. After the multi-layer wrapping, the insulation thickness at the connection is 1.25 times the original insulation thickness, thereby enhancing the insulation strength of the connection.

[0056] The present invention uses high-frequency welding to weld insulated copper stranded wire 10 and rectangular copper wire 20. It features high welding speed, strong current-carrying capacity, a small operating area, and smooth, rounded electrodes. A silver welding rod is used to guide the solder liquid, increasing the silver solder liquid fill rate during the welding process. The present invention offers advantages such as ease of operation, easy temperature control, high welding speed, and smooth, no-frills welds.

[0057] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art will appreciate that the technical solutions described in the above embodiments may be modified or some or all of the technical features thereof may be replaced with equivalents, and that such modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the various embodiments of the present invention.

Claims

1. A high-frequency welding method for transformer leads, characterized in that: The method is to weld the insulated copper strands and flat copper wires in the transformer by high-frequency welding. The following steps are involved: S1: Strip the insulated copper stranded wire to be welded, and round the ends of the insulated copper stranded wire and the flat copper wire; When a paint film is provided on the flat copper wire, the flat copper wire is stripped of the paint by a high-frequency induction heating method; S2: inserting the insulated copper stranded wire and the flat copper wire to be welded into a connecting sleeve, adding solder to the connection between the insulated copper stranded wire and the flat copper wire, and heating the connecting sleeve using a high-frequency welding inductor; The connecting sleeve is provided with a feeding hole, and the feeding hole is used to place a silver welding rod between the insulated copper stranded wire and the flat copper wire; A U-shaped inductor is used to heat the connecting sleeve from both ends to the middle; During the heating process, when the temperature of the connecting sleeve is higher than the melting point of the silver solder rod, add the silver solder rod into the connecting sleeve through the feeding hole; when the solder overflows from both ends of the connecting sleeve and the feeding hole, stop adding the silver solder rod; After stopping the feeding, repeat heating the connecting sleeve 2 to 3 times; S3: After heating, cool the connecting sleeve; use asbestos cloth soaked in 94%-96% alcohol to cool the connecting sleeve; S4: Insulate the connecting sleeve.

2. The high-frequency welding method for transformer leads according to claim 1, characterized in that: In step S1, the wire stripping is performed by using a step-by-step cutting method to strip the insulation layer of the insulated copper stranded wire into a cone shape, and the length of the cone is at least ten times the thickness of the insulation layer.

3. The high-frequency welding method for transformer leads according to claim 1, characterized in that: In step S1 , copper tapes are wound around ends of insulated copper strands and / or rectangular copper wires.

4. The high-frequency welding method for transformer leads according to claim 1, characterized in that: In step S2: a chromium layer or a nickel layer with a thickness of 18-22 μm is provided on the surface of the connecting sleeve.

5. The high-frequency welding method for transformer leads according to claim 1, characterized in that: In step S2: the position of the feed hole corresponds to the connection position of the insulated copper stranded wire and the flat copper wire.

6. The high-frequency welding method for transformer leads according to claim 1, characterized in that: In step S2: the center of the feed hole is located at the axial midpoint of the connecting sleeve.

7. The high-frequency welding method for transformer leads according to claim 1, characterized in that: In step S2: the axial length of the feed hole along the connecting sleeve is 1.8-2.2 mm, the circumferential length of the feed hole along the connecting sleeve is 7.5-8.5 mm, the inner diameter of the connecting sleeve is 9.8-28.1 mm, the outer diameter of the connecting sleeve is 14.0-33.3 mm, the single-side wall thickness of the connecting sleeve is 2.05-2.5 mm, and the length of the connecting sleeve is 48-70 mm.

8. The high-frequency welding method for transformer leads according to claim 1, characterized in that: In step S4: before the insulation treatment, the oxide layer and foreign matter on the connecting sleeve and the welding point are removed.

9. The high-frequency welding method for transformer leads according to claim 8, characterized in that: Step S4 specifically includes: wrapping at least one layer of semi-conductive paper on the connecting sleeve in a half-fold manner, and then wrapping at least two layers of crepe paper in a half-fold manner, wherein the crepe paper is crepe paper that has been stretched by 70% to 90%.

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