A multi-stage processing forming process for copper wire rod

Abstract

This invention discloses a multi-stage processing and forming process for copper wire, including a drawing forming process and a rolling forming process. The drawing forming process straightens the copper wire and refines its shape, while the rolling forming process flattens the copper wire, increasing its width-to-thickness ratio. The drawing forming and rolling forming processes are used alternately to process the copper wire, with the final forming process being a drawing forming process, resulting in a flat wire. A winding mechanism (2) is set after the final forming process to collect the formed flat wire and provide traction force. A traction mechanism (11) is set between the drawing forming and rolling forming processes to provide traction assistance for the copper wire's forward movement, enabling the copper wire to continuously move through all the drawing forming and rolling forming processes, achieving continuous production. This invention has the advantages of high production efficiency, low production failure rate, high production qualification rate, no sharp edges, and a small footprint for process implementation.

Description

Technical Field

[0001] This invention belongs to the field of enameled wire, and particularly relates to a multi-stage processing and forming process for copper wire in enameled wire. Background Technology

[0002] The core components of enameled wire include the inner copper wire and the outer enamel film. Copper wire is mainly divided into round wire and flat wire. The advantage of round wire is that it is easy to form and process, while the advantage of flat wire is that it has a high space utilization rate, can improve the slot fill factor, resulting in a high power density and better heat dissipation. Therefore, flat wire is generally used for enameled wire in the power motor of new energy vehicles.

[0003] Generally speaking, the larger the width-to-thickness ratio of flat wire, the higher the slot fill factor. Ordinary flat wire (width-to-thickness ratio less than 4:1), such as the flat wire width and thickness of a certain motor with 2.6, can be obtained by drawing with a die. However, ultra-wide flat wire (width-to-thickness ratio greater than 8:1) is easily torn when formed by drawing and is generally obtained by rolling.

[0004] Compared to ordinary flat wire, ultra-wide flat wire has a greater amount of copper filling in the same stator volume, making it easier to meet the requirements of "small size and high power" for power motors in the future development of new energy vehicles.

[0005] Ultra-wide flat wire is not yet widely used, mainly because there are three common methods for forming flat wire: drawing, rolling, and slitting. For drawing, a copper rod is pulled through a multi-stage drawing die. When the width-to-thickness ratio of the drawn flat wire is large, the tensile resistance of the multi-stage drawing die accumulates at the end, making the copper wire prone to breakage and resulting in a high production failure rate. For rolling, a round wire is passed between two rolls of a rolling mill and rolled into a flat wire. However, if the round wire has defects such as hard bending deformation or roundness deviation, the rolled flat wire will have corresponding defects such as bending and inconsistent cross-sectional shapes. A larger width-to-thickness ratio will further amplify these defects, leading to a lower yield rate. Furthermore, the rolled copper wire will have relatively sharp edges on both sides of the rolling plane, causing stress concentration in the paint film during subsequent painting, making the paint film prone to cracking. The longitudinal shearing method involves directly cutting copper strips into the required flat wires. However, during the cutting process, the flat wires are affected by the lateral force of the cutting tool, causing them to bend to the side. Furthermore, the edges formed after cutting are too sharp, which can cause stress concentration in the paint film during subsequent painting, making the paint film prone to cracking and unusable. Summary of the Invention

[0006] The purpose of this invention is to provide a multi-stage processing and forming process for copper wire. This invention has the advantages of high production efficiency, low failure rate, high yield rate, no sharp edges, and a small footprint.

[0007] The technical solution of this invention is a multi-stage processing and forming process for copper wire, including a drawing forming process and a rolling forming process. The drawing forming process straightens the copper wire and refines its shape, while the rolling forming process flattens the copper wire to improve its width-to-thickness ratio. The drawing forming process and the rolling forming process are used alternately to process the copper wire, with the final forming process being a drawing forming process, resulting in a flat wire with rounded edges and a width-to-thickness ratio ≥8. After annealing, pickling, washing, and drying, the flat wire is used to manufacture enameled wire for power motors in new energy vehicles.

[0008] In the aforementioned multi-stage processing and forming process for copper wire, a winding mechanism is set up after the final forming process. The winding mechanism collects the formed flat wire and provides traction force for the copper wire. A traction mechanism is set up between the drawing and forming process and the rolling forming process to provide traction assistance for the copper wire to move forward, so that the copper wire can move continuously through all the drawing and forming processes and the rolling forming process, thereby realizing continuous production.

[0009] In the aforementioned multi-stage processing and forming process for copper wire, a softening process is set between the drawing and forming process and the rolling process. The softening process heats the copper wire to 450-550℃ to avoid excessive hardening and cracking during the forming process.

[0010] In the aforementioned multi-stage processing and forming process for copper wire, the drawing and rolling processes are carried out in an oxygen-free workshop with an oxygen concentration of less than 100 ppm.

[0011] In the aforementioned multi-stage processing and forming process for copper wire, the copper wire is subjected to two or more continuous rolling processes during the rolling forming step.

[0012] In the aforementioned multi-stage processing and forming process for copper wire, the multi-stage processing and forming process is implemented by a multi-stage forming device set in an oxygen-free workshop. In the direction of copper wire movement, the multi-stage forming device includes an unwinding mechanism and a winding mechanism. Multiple wire drawing dies are provided between the unwinding mechanism and the winding mechanism. At least two rolling mills are provided between adjacent wire drawing dies. A softening mechanism and a traction mechanism are provided between the wire drawing die and the rolling mill.

[0013] In the aforementioned multi-stage processing and forming process of copper wire, the softening mechanism is an induction coil connected to an electromagnetic induction heating device, and the copper wire passes through the induction area of ​​the induction coil.

[0014] In the aforementioned multi-stage processing and forming process of copper wire, the traction mechanism includes a frame, a speed-regulating motor is provided on the frame, and a roller is provided at the output end of the speed-regulating motor and rotatably connected to the frame. A spiral material groove is provided on the outer surface of the roller, and the copper wire is spirally wound along the material groove and passes through the roller. At least one floating pressure roller is provided on the outer side of the roller, and the pressure roller presses the copper wire tightly against the roller to increase the friction between the copper wire and the roller.

[0015] In the aforementioned multi-stage processing and forming process for copper wire, the traction mechanism is located between the softening mechanism and the drawing die, and the copper wire passes through the axis of the induction coil.

[0016] In the aforementioned multi-stage processing and forming process of copper wire, the roller is a hollow structure. One end of the roller is connected to a speed-regulating motor through a magnetic coupling, and the other end of the roller is provided with a conductive slip ring. The fixed end of the conductive slip ring is connected to the frame through a bracket, and the rotating end of the conductive slip ring is connected to an induction coil. The induction coil is fixed inside the roller, and a gap of 0.5-2mm is formed between the induction coil and the roller. Both ends of the roller are provided with heat dissipation holes.

[0017] Compared with existing technologies, this invention combines the existing drawing and rolling methods, alternating between them. An additional traction mechanism is added at the end of each drawing operation to provide traction force. This achieves continuous production and high efficiency while avoiding the accumulation of resistance at the end of multiple drawing operations that could lead to copper wire breakage, resulting in a lower production failure rate. Furthermore, the copper wire is drawn and trimmed before rolling, resulting in high straightness, a regular shape, and no defects, thus improving the product qualification rate. Finally, the forming process is completed by drawing, refining the copper wire's shape. The resulting flat wire has rounded corners along its edges, preventing stress concentration in the enamel film during enameling and avoiding cracking. Moreover, because rolling allows for greater deformation of the copper wire, it can be formed into flat wires in relatively fewer passes, requiring a shorter production line and a smaller footprint. Therefore, this invention has the advantages of high production efficiency, low production failure rate, high product qualification rate, no sharp edges, and a smaller footprint. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the layout of the multi-stage molding device in the workshop according to Example 1.

[0019] Figure 2 This is a schematic diagram of the traction mechanism in Example 1.

[0020] Figure 3 This is an axial schematic diagram of the roller in Example 1.

[0021] Figure 4 This is a schematic diagram showing the change in the cross-sectional shape of the copper wire during the forming process in Example 1.

[0022] Figure 5 This is a schematic diagram of the layout of the multi-stage molding device in the workshop according to Example 2.

[0023] The labels in the attached diagram are as follows: 1-unwinding mechanism, 2-winding mechanism, 3-drawing die, 4-rolling mill, 5-induction coil, 6-frame, 7-speed regulating motor, 8-roller, 9-feed trough, 10-pressure roller, 11-traction mechanism, 12-magnetic coupling, 13-conductive slip ring, 14-support, 15-slider, 16-slide rail, 17-compression spring, 18-heat dissipation hole. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0025] Example 1: A multi-stage processing technology for copper wire, including a drawing process and a rolling process. The drawing process straightens the copper wire and refines its shape. The rolling process flattens the copper wire twice or more to increase its width-to-thickness ratio. The drawing and rolling processes are used alternately, with the final forming process being a drawing process. A final refinement of the copper wire's shape yields a flat wire with a width-to-thickness ratio ≥8 and rounded corners. After annealing, pickling, washing, and drying, the flat wire is used to manufacture enameled wire for new energy vehicle power motors.

[0026] A winding mechanism 2 is set up after the final forming process. The winding mechanism 2 collects the formed flat wire and provides traction force for the copper wire. A traction mechanism 11 is set up between the drawing forming process and the rolling forming process to provide traction assistance for the copper wire to move forward, so that the copper wire can move continuously through all the drawing forming process and the rolling forming process to achieve continuous production.

[0027] A softening process is set between the drawing and rolling processes. The copper wire is heated to 450-550℃ during the softening process to prevent it from hardening and cracking due to cold work hardening during the forming process.

[0028] like Figure 1 As shown, the multi-stage processing and molding process is implemented through a multi-stage molding device set up in an oxygen-free workshop, where the gas is nitrogen and the oxygen concentration is about 100 ppm.

[0029] In the direction of copper wire movement, the multi-stage forming device includes an unwinding mechanism 1 and a winding mechanism 2. Both the unwinding mechanism 1 and the winding mechanism 2 are prior art. The copper wire coil is disposed in the unwinding mechanism 1, which continuously unwinds the copper wire, as in the copper wire coil unwinding device of application number 201810841446.5 and the copper wire unwinding system for transformer coil winding of application number 202210270424.4. The winding mechanism 2 pulls the copper wire, provides traction assistance for the copper wire to move forward, and rewinds the formed flat wire into a coil, as in the bare copper wire bundling and winding device for storage of application number 202210702720.7, the copper wire winding device with a collection and straightening mechanism of application number 202211347391.5, and the copper wire winding mechanism of application number 202422872791.9.

[0030] Multiple drawing dies 3 are provided between the unwinding mechanism 1 and the winding mechanism 2. At least two rolling mills 4 are provided between adjacent drawing dies 3. The copper wire is flattened once each time it passes through a rolling mill 4. A softening mechanism and a traction mechanism 11 are provided between the drawing die 3 and the rolling mill 4.

[0031] The softening mechanism is the induction coil 5 connected to the electromagnetic induction heating device, with copper wire passing through the axis of the induction coil 5.

[0032] exist Figure 1 In the dashed frame, the wire drawing die 3, the traction mechanism 11, the softening mechanism, and the rolling mill 4 constitute a unit. Multiple units can be set according to the width-to-thickness ratio of the flat wire to reduce the amount of deformation during each forming. In Example 1, two units are taken, and each unit has two rolling mills 4.

[0033] The traction mechanism 11 includes a frame 6, on which a speed-regulating motor 7 is mounted. The output end of the speed-regulating motor 7 is provided with a roller 8 that is rotatably connected to the frame 6. A spiral material groove 9 is provided on the outer surface of the roller 8, and copper wire is spirally wound along the material groove 9 and passes through the roller 8.

[0034] Four floating pressure rollers 10 are provided on the outer side of the roller 8. The four pressure rollers 10 are evenly distributed circumferentially and press the copper wire tightly against the roller 8, increasing the friction between the copper wire and the roller 8. Each end of the pressure roller 10 is provided with a slider 15, and the pressure roller 10 is rotatably connected to the slider 15. The slider 15 is connected to the frame 6 through a slide rail 16. The slider 15 is provided with a compression spring 17 that connects to the frame 6. The compression spring 17 applies pressure to the slider 15, causing the pressure roller 10 to move towards the axis of the roller 8.

[0035] The roller 8 is a hollow structure. One end of the roller 8 is connected to the speed-regulating motor 7 via a magnetic coupling 12, and the other end of the roller 8 is equipped with a conductive slip ring 13. The fixed end of the conductive slip ring 13 is connected to the frame 6 via a bracket 14, and the rotating end of the conductive slip ring 13 is connected to the induction coil 5. The induction coil 5 is fixed inside the roller 8, and a gap of 0.5-2mm is formed between the induction coil 5 and the roller 8, so they are not in direct contact. The induction coil 5 is electrically connected to the electromagnetic induction heating equipment through the conductive slip ring 13. Both ends of the roller 8 are equipped with heat dissipation holes 18.

[0036] Working principle of traction mechanism 11: The speed-regulating motor 7 adjusts its speed according to the moving speed of the copper wire. The speed-regulating motor 7 drives the roller 8 to rotate through the magnetic coupling 12. The output torque of the speed-regulating motor 7 can be adjusted through the magnetic coupling 12. This torque should match the pulling force required for the copper wire to pass through the previous drawing die 3. The copper wire spirals through the feed groove 9. The cross-sectional shape of the feed groove 9 should match the cross-sectional shape of the current copper wire, with the copper wire slightly exceeding the feed groove 9. The pressure roller 10 obtains downward pressure through the compression spring 17, pressing the copper wire tightly against the roller 8. The friction between the copper wire and the roller 8 increases, and the roller 8 provides more sufficient traction force for the movement of the copper wire. The induction coil 5 heats the copper wire wound on the roller 8 to 450-550℃. Due to the large stroke of the copper wire after winding, the heating time is longer, resulting in a better softening effect. The heat inside the roller 8 is discharged through the heat dissipation holes 18 to avoid overheating inside and adversely affecting the induction coil 5.

[0037] The working principle of the multi-stage forming device: The copper wire coil is placed on the unwinding mechanism and is released at a uniform speed. The traction mechanism provides auxiliary tension for the copper wire to pass through the corresponding drawing die 3. When the copper wire passes through the drawing die 3, its shape is trimmed, eliminating surface defects and bends. To reduce tensile resistance, a small amount of drawing oil can be added to the copper wire at the drawing die 3, but this is not necessary. The tension required for the copper wire to pass through the corresponding drawing die 3 is provided by both the traction mechanism and the rolling mill. After passing through the drawing die 3, the copper wire is heated to 450-550℃ under the action of the induction coil 5. The work hardening effect generated during the stretching process is basically eliminated, the stress on the copper wire basically disappears, and the hardness is restored. Then, it passes through the rolling mill 4 and is flattened.

[0038] by Figure 1Taking a copper wire with an original diameter of 3.8mm, which needs to be rolled into a flat wire with a thickness of 1mm, a width of 8mm, and a corner radius of 0.4mm as an example, the process is as follows: When the copper wire passes through the first drawing die 3, it is trimmed to a diameter of 3.5mm; when it passes through the first and second rolling mills 4, it is rolled to a thickness of 2.5mm and 1.5mm respectively; when it passes through the second drawing die 3, the shape of the copper wire is refined according to the shape of the copper wire rolled by the second rolling mill 4, eliminating surface defects and making the cross-sectional area of ​​the trimmed copper wire about 8.8 square millimeters; when it passes through the third and fourth rolling mills 4, it is rolled to a thickness of 1.2mm and 1.03mm respectively; when it passes through the third drawing die 3, the shape is refined again, and the final flat wire with a thickness of 1mm, a width of 8mm, and a corner radius of 0.4mm is obtained. The last drawing has the least amount of deformation, mainly to change the sharp edges formed during the flattening of the copper wire into rounded corners.

[0039] By setting up a speed-regulating motor to adapt to the production line speed adjustment; by using a magnetic coupling to avoid the hard transmission of production line load fluctuations to the speed-regulating motor, the failure rate is reduced; by integrating the induction coil into the inside of the roller, the copper wire is spirally wound and heated by the roller, which increases the heating stroke of the copper wire, that is, increases the heating time of the copper wire, improves the softening effect of the copper wire, avoids the copper wire breaking during the forming process, further improves the forming success rate, and greatly shortens the production line length, effectively reducing the floor space.

[0040] Example 2: Unlike Example 1, the traction mechanism 11 is located between the softening mechanism and the drawing die 3, and the copper wire passes through the axis of the induction coil 5. The roller 8 in Example 2 can be a solid structure.

[0041] Compared to Example 2, Example 1, where the copper wire is wound around the roller 8 for heating, occupies less production line length, making the equipment easier to arrange. It also results in less heat loss and greater energy efficiency. However, the heat from the copper wire is transferred to the inside of the roller 8, and the built-in induction coil 5 does not provide excellent heat dissipation. The workshop may require an additional air conditioning system, or, in hot weather, a blower may be used to axially blow air onto the roller 8 to accelerate heat dissipation. Example 2 has a simpler structure, with the induction coil 5 externally mounted for better heat dissipation.

[0042] In the description of the embodiments, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations.

Claims

1. A multi-stage process for forming copper wire rod, the process comprising: The process includes drawing and rolling processes. The drawing process straightens and refines the shape of the copper wire, while the rolling process flattens the copper wire to increase its width-to-thickness ratio. The drawing and rolling processes are used alternately to process the copper wire, with the final forming process being the drawing process, resulting in a flat wire with rounded edges and a width-to-thickness ratio ≥8. After annealing, pickling, washing, and drying, the flat wire is used to manufacture enameled wire for power motors in new energy vehicles. ​ 2. The multi-stage processing forming process of copper wire rod according to claim 1, characterized in that: A winding mechanism (2) is set up after the final forming process. The winding mechanism (2) collects the formed flat wire and provides traction force for the copper wire. A traction mechanism (11) is set up between the drawing forming process and the rolling forming process to provide traction assistance for the copper wire to move forward, so that the copper wire can move continuously through all the drawing forming process and the rolling forming process to achieve continuous production.

3. The multi-stage processing forming process of copper wire rod according to claim 2, characterized in that: A softening process is set between the drawing and rolling processes. The copper wire is heated to 450-550℃ during the softening process to prevent it from hardening and cracking due to cold work hardening during the forming process.

4. The multi-stage processing forming process of copper wire rod according to claim 3, characterized in that: The drawing and rolling processes are carried out in an oxygen-free workshop with an oxygen concentration of less than 100 ppm.

5. The multi-stage processing forming process of copper wire rod according to claim 1 or 3, characterized in that: In the rolling forming process, the copper wire is rolled continuously twice or more.

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