Manufacturing method for tin-plated copper wire

Abstract

The present invention provides a method for manufacturing tin-plated copper wire that achieves uniform plating thickness in both the circumferential and longitudinal directions. [Solution] A method for manufacturing tin-plated soft copper wire according to one embodiment comprises an immersion step, a first slitting step, and a second slitting step. In the immersion step, the soft copper wire CW is passed through a plating tank 20 in which tin plating solution is stored to allow the tin plating solution to adhere to the surface of the soft copper wire CW. In the first slitting step, the soft copper wire CW is passed through a slitting mechanism 30 to remove a portion of the tin plating solution adhering to the surface of the soft copper wire CW. In the second slitting step, the soft copper wire CW is passed through a die 40 to remove a portion of the tin plating solution adhering to the surface of the soft copper wire CW. The slitting mechanism 30 is provided around the soft copper wire CW and comprises a scraping section that surrounds the entire circumference of the soft copper wire CW, and a heat-shrinkable tube provided around the scraping section and surrounding the entire circumference of the scraping section. The scraping section is tightened radially inward by the heat-shrinkable tube.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a tin-plated copper wire.

Background Art

[0002] Generally, the plating film of a tin-plated copper wire is formed by a melting plating method. For example, when forming a plating film on the surface of soft copper wire, which is an example of copper wire, the soft copper wire is immersed in molten tin (Sn). In the following description, molten tin (Sn) may be referred to as "tin plating solution".

[0003] It is desirable that the thickness (plating thickness) of the plating film formed as described above is uniform in both the circumferential direction and the longitudinal direction of the copper wire. Therefore, when forming the plating film of a tin-plated copper wire by the melting plating method, an operation or process for removing the excess tin plating solution adhering to the surface of the copper wire to adjust the plating thickness is required. Such an operation or process is generally called "drawing". For example, Patent Document 1 describes the adjustment of the plating thickness using a drawing die.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to manufacture a higher-quality tin-plated copper wire, further uniformization of the plating thickness is required.

[0006] An object of the present invention is to provide a method for manufacturing a tin-plated copper wire that uniformizes the plating thickness in both the circumferential direction and the longitudinal direction.

Means for Solving the Problems

[0007] A method for manufacturing tin-plated copper wire according to one embodiment comprises an immersion step, a first slitting step performed after the immersion step, and a second slitting step performed after the first slitting step. In the immersion step, the copper wire is passed through a plating tank containing a tin plating solution to allow the tin plating solution to adhere to the surface of the copper wire. In the first slitting step, the copper wire is passed through a slitting mechanism to remove a portion of the tin plating solution adhering to the surface. In the second slitting step, the copper wire is passed through a die to remove a portion of the tin plating solution adhering to the surface. The slitting mechanism used in the first slitting step comprises a scraping section provided around the copper wire and surrounding the entire circumference of the copper wire, and a heat-shrinkable tube provided around the scraping section and surrounding the entire circumference of the scraping section. The scraping section is tightened radially inward by the heat-shrinkable tube. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method for manufacturing tin-plated copper wire that makes the plating thickness uniform in both the circumferential and longitudinal directions. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing an example of a manufacturing apparatus capable of carrying out a copper wire manufacturing method according to one embodiment. [Figure 2] Figure 1 is a longitudinal cross-sectional view of the aperture mechanism. [Figure 3] Figure 1 is a cross-sectional view of the aperture mechanism. [Figure 4] Figures 2 and 3 are explanatory diagrams showing an example of a method for manufacturing the aperture mechanism. [Figure 5] Figures 2 and 3 are other explanatory diagrams showing an example of a method for manufacturing the aperture mechanism. [Figure 6] Figures 2 and 3 are other explanatory diagrams showing an example of a method for manufacturing the aperture mechanism. [Figure 7] Figures 2 and 3 are other explanatory diagrams showing an example of a method for manufacturing the aperture mechanism. [Figure 8] Figures 2 and 3 are other explanatory diagrams showing an example of a method for manufacturing the aperture mechanism. [Figure 9] Figures 2 and 3 are other explanatory diagrams showing an example of a method for manufacturing the aperture mechanism. [Modes for carrying out the invention]

[0010] The embodiments of the present invention will be described in detail below with reference to the drawings. In all drawings used to illustrate the embodiments, the same or substantially identical components and elements will be denoted by the same reference numerals. Furthermore, components and elements that have already been described will not be repeated in principle.

[0011] <Overview> The method for manufacturing tin-plated copper wire according to this embodiment comprises at least an immersion step, a first squeegee step, and a second squeegee step. Details of each step will be explained later, but the immersion step is a step of applying tin plating solution to the surface of the copper wire. On the other hand, the first squeegee step and the second squeegee step are steps of removing the tin plating solution from the surface of the copper wire.

[0012] Figure 1 is a schematic diagram showing an example of a manufacturing apparatus capable of carrying out the copper wire manufacturing method according to this embodiment. The manufacturing apparatus 10 shown in Figure 1 includes a plating tank 20, a drawing mechanism 30, a die 40, and a winding machine 50.

[0013] <Soaking process> In the immersion process of this embodiment, the copper wire CW is passed through a plating tank 20 containing a tin plating solution. Alternatively, in the immersion process of this embodiment, the copper wire CW is immersed in the tin plating solution stored in the plating tank 20. Therefore, when the immersion process is performed, the tin plating solution adheres to the surface of the copper wire CW. In this embodiment, the copper wire CW is a soft copper wire with a diameter of 2.0 mm. Therefore, in the following description, the copper wire CW will be referred to as "soft copper wire CW".

[0014] More specifically, the soft copper wire CW drawn from a drum (not shown) is caused to travel (move) in the direction indicated by the arrow in FIG. 1, and in the process, it passes through the plating bath 20. More specifically, the soft copper wire CW drawn from a drum (not shown) is obliquely downwardly drawn into the plating bath 20. Next, the traveling direction (moving direction / advancing direction) of the soft copper wire CW is converted obliquely upward by the roller 21 provided in the plating bath 20. Thereafter, the soft copper wire CW is drawn out from the plating bath 20.

[0015] Note that the plating bath 20 includes a heater capable of heating tin to a temperature above its melting point. The tin introduced into the plating bath 20 is heated to a temperature above its melting point by the heater provided in the plating bath 20 and melts. Thereafter, the molten tin is maintained in a molten state by the heater.

[0016] <First drawing process> The first drawing process is carried out after the immersion process. In the first drawing process, the soft copper wire CW drawn from the plating bath 20 is passed through a drawing mechanism 30. FIG. 2 is a longitudinal sectional view of the drawing mechanism 30 shown in FIG. 1. FIG. 3 is a cross-sectional view of the drawing mechanism 30 shown in FIG. 1. However, for reasons of convenience, the scales of FIGS. 2 and 3 are different.

[0017] The length L of the drawing mechanism 30 shown in FIG. 2 is approximately 10 [cm]. As shown in FIGS. 2 and 3, the drawing mechanism 30 is a cylindrical body having an inlet 31 and an outlet 32. In the present embodiment, the soft copper wire CW drawn from the plating bath 20 is drawn into the inside of the drawing mechanism 30 from the inlet 31 and drawn out from the outside of the drawing mechanism 30 from the outlet 32. That is, in the first drawing process, the soft copper wire CW drawn from the plating bath 20 is passed through the drawing mechanism 30.

[0018] <The squeezing mechanism 30 removes a part of the tin plating solution adhering to the surface of the passing soft copper wire CW. More specifically, the squeezing mechanism 30 shakes off (drops) a part of the tin plating solution adhering to the surface of the passing soft copper wire CW. In other words, the squeezing mechanism 30 squeezes out a part of the tin plating solution adhering to the surface of the passing soft copper wire CW. The squeezing mechanism 30 mainly shakes off (squeezes out) the tin plating solution by the peripheral edge of the inlet 31.

[0019] Therefore, when the first squeezing process is executed, a part of the tin plating solution adhering to the surface of the soft copper wire CW in the dipping process is removed. Viewed from another perspective, the first squeezing process is a process of removing the excess tin plating solution adhering to the surface of the soft copper wire CW.

[0020] The squeezing mechanism 30 includes a squeezing part (shigoki bu) 33 and a heat shrinkable tube 34. The squeezing part 33 is provided around the soft copper wire CW and surrounds the entire circumference of the soft copper wire CW. The heat shrinkable tube 34 is provided around the squeezing part 33. Furthermore, the heat shrinkable tube 34 surrounds the entire circumference of the squeezing part 33 over the entire length of the squeezing part 33.

[0021] Viewed from another perspective, the squeezing mechanism 30 is a double - structure tunnel through which the soft copper wire CW drawn out from the plating tank 20 passes. The squeezing part 33 constitutes the inner side (inner layer) of the tunnel, and the heat shrinkable tube 34 constitutes the outer side (outer layer) of the tunnel.

[0022] Figs. 4 to 9 are explanatory diagrams showing an example of the manufacturing method of the squeezing mechanism 30. As mainly shown in Figs. 4 and 5, a braided tape 35 is wound horizontally around the outer peripheral surface of the soft copper wire CW to form the squeezing part 33. More specifically, the braided tape 35 is wound horizontally around the outer peripheral surface of the soft copper wire CW at a lap rate (lap width) of 1 / 3 to 1 / 2 to form the squeezing part 33.

[0023] In other words, the squeegee portion 33 of the diaphragm mechanism 30 is made up of a braided tape 35 that is wound horizontally around a soft copper wire CW. The width W of the braided tape 35 is 3.0 to 5.0 mm. The individual wires that make up the braided tape 35 are tin-plated soft copper wires, and their diameter is 0.2 to 0.6 mm.

[0024] However, the width W of the braided tape 35 can be changed as appropriate. Also, the strands are not limited to tin-plated soft copper wire, and the diameter of the strands can be changed as appropriate.

[0025] Next, as mainly shown in Figures 6 and 7, the heat-shrinkable tube 34 is placed over the braided tape 35 wrapped around the outer surface of the soft copper wire CW. In other words, the tack portion 33 provided around the soft copper wire CW is inserted into the heat-shrinkable tube 34. As a result, the tack portion 33 is covered by the heat-shrinkable tube 34.

[0026] Subsequently, as mainly shown in Figures 8 and 9, the heat-shrinkable tube 34 covering the braided tape 35 (tightening portion 33) is heated and shrunk. At this time, the heat-shrinkable tube 34 is heated as evenly as possible along its entire length and circumference.

[0027] Then, the braided tape 35 (tightening portion 33) is tightened radially inward by the shrunk heat shrink tube 34. Furthermore, the tightening portion 33 is tightened evenly or substantially evenly along its entire length and circumference. As a result, the inner surface of the tightening portion 33 is pressed against the outer surface of the soft copper wire CW with even or substantially even force.

[0028] The heat shrink tubing 34 is not limited to a specific type of heat shrink tubing. However, the heat shrink tubing 34 is required to have heat resistance such that it does not dissolve or deform when in contact with tin plating solution. Furthermore, the heat shrink tubing 34 is also required to have a uniform shrinkage rate. An example of a heat shrink tubing that satisfies these requirements and can be used as the heat shrink tubing 34 in this embodiment is the heat shrink tubing manufactured by Denka Electron Co., Ltd. (model numbers VL-3.2 or VL-4.8).

[0029] <Second pressing process> The second throttling process is performed after the first throttling process. Refer to Figure 1 again. In the second throttling process, the soft copper wire CW that has passed through the throttling mechanism 30 is passed through the die 40. The die 40 is located downstream (forward) of the throttling mechanism 30 in the direction of travel of the soft copper wire CW and is supported by a support member (not shown).

[0030] Since the diaphragm mechanism 30 and the die 40 are arranged in the above-described positional relationship, the soft copper wire CW drawn out from the plating bath 20 passes through the diaphragm mechanism 30 and the die 40 in that order. The die 40, like the diaphragm mechanism 30, removes a portion of the tin plating solution adhering to the surface of the passing soft copper wire CW. Therefore, in the following explanation, the die 40 may be referred to as the "diaphragm die 40".

[0031] When the second drawing process is performed, a portion of the tin plating solution adhering to the surface of the soft copper wire CW is removed. In other words, the second drawing process is a process for removing excess tin plating solution adhering to the surface of the soft copper wire CW. As a result, a coating of tin plating solution is formed on the surface of the soft copper wire CW, having a thickness corresponding to the difference between the outer diameter of the soft copper wire CW and the inner diameter of the drawing die 40.

[0032] Here, the diaphragm mechanism 30 is positioned upstream (in front of) the diaphragm die 40 in the direction of travel of the soft copper wire CW, and abuts against the diaphragm die 40. More specifically, one end (front) of the diaphragm mechanism 30 abuts against one end (rear) of the diaphragm die 40. As a result, the movement of the diaphragm mechanism 30 in the direction of travel of the soft copper wire CW is restricted by the diaphragm die 40.

[0033] Subsequently, the soft copper wire CW that has passed through the drawing die 40 is wound onto a drum (bobbin) 51 which is rotated by a winding machine 50. The tin plating film formed on the surface of the soft copper wire CW is cooled and hardened between the time the soft copper wire CW passes through the drawing die 40 and when it is wound onto the drum 51. As a result, a plating film of a predetermined thickness is formed on the surface of the soft copper wire CW.

[0034] As described above, the manufacturing method for soft copper wire according to this embodiment includes an immersion step, a first throttling step performed after the immersion step, and a second throttling step performed after the first throttling step. In other words, in the manufacturing method according to this embodiment, the step of removing the tin plating solution attached to the surface of the soft copper wire CW in the immersion step is performed two or more times. Therefore, the plating thickness can be controlled more accurately compared to other manufacturing methods in which the step of removing the tin plating solution is performed only once.

[0035] Furthermore, the throttling mechanism 30 used in the first throttling process has a scraping section 33 that is pressed with an even or nearly even force over the entire circumference of the soft copper wire CW. Therefore, after passing through the throttling mechanism 30, the tin plating solution adheres uniformly or nearly uniformly in the circumferential direction to the surface of the soft copper wire CW. In other words, the tin plating solution adheres uniformly or nearly uniformly in the circumferential direction to the surface of the soft copper wire CW after the first throttling process. As a result, the accuracy of adjusting the plating thickness in the second throttling process is improved.

[0036] Furthermore, the pressing of the rubbing section 33 against the soft copper wire CW is achieved by the shrinkage of the heat shrink tubing 34. In other words, the rubbing section 33 can be pressed against the soft copper wire CW with uniform force as long as the heat shrink tubing 34 is heated evenly. Therefore, there is no need to adjust the pressing force of the rubbing section 33 against the soft copper wire CW based on the worker's experience or intuition.

[0037] The present invention is not limited to the embodiments described above, and various modifications are possible without departing from its spirit. For example, the base material of the tin-plated copper wire produced by the method for manufacturing tin-plated soft copper wire of the present invention may be a copper wire other than soft copper wire. More specifically, the copper wire immersed in the tin plating solution in the immersion step may be any of soft copper wire, hard copper wire, semi-hard copper wire, or copper alloy wire. An example of a copper alloy wire is a copper alloy wire containing nickel or tin.

[0038] The squeegee portion of the aperture mechanism can also be constructed from a braided tube. More specifically, in another embodiment, the squeegee portion of the aperture mechanism is formed from a braided tube through which copper wire is inserted. In this embodiment as well, the squeegee portion (braided tube) is tightened radially inward by a heat-shrinkable tube covering it, and is evenly pressed against the outer surface of the copper wire.

[0039] Furthermore, the braided tape 35 shown in Figures 4 and 5 can be replaced with a resin cord (for example, a fluororesin cord). More specifically, in another embodiment, the gripping portion of the throttling mechanism is formed by a resin cord that is spirally wrapped around the outer surface of the copper wire. In this embodiment as well, the gripping portion (resin cord) is tightened radially inward by a heat-shrinkable tube covering it and is evenly pressed against the outer surface of the copper wire. [Explanation of Symbols]

[0040] 10...Manufacturing equipment, 20...Plating tank, 21...Roller, 30...Squeezing mechanism, 31...Inlet, 32...Outlet, 33...Squeezing section, 34...Heat shrink tubing, 35...Braided tape, 40...Die (Squeezing die), 50...Winding machine, 51...Drum (Bobbin), CW...Copper wire (Soft copper wire)

Claims

1. A copper wire is passed through a plating tank containing a tin plating solution in an immersion step to deposit the tin plating solution onto the surface of the copper wire. Following the immersion step, a first throttling step is performed in which the copper wire is passed through a throttling mechanism to remove a portion of the tin plating solution adhering to the surface. The process includes a second drawing step, in which the copper wire is passed through a die to remove a portion of the tin plating solution adhering to the surface, after the first drawing step. The throttling mechanism comprises a scrubbing section provided around the copper wire and surrounding the entire circumference of the copper wire, and a heat-shrinkable tube provided around the scrubbing section and surrounding the entire circumference of the scrubbing section. A method for manufacturing tin-plated copper wire, wherein the aforementioned tightening portion is tightened radially inward by the heat-shrinkable tube.

2. The method for manufacturing a tinned copper wire according to claim 1, wherein the throttling mechanism restricts the movement of the copper wire in the direction of travel by abutting one end against the die.

3. The method for manufacturing a tin-plated copper wire according to claim 2, wherein the stripping portion is composed of a braided tape that is wound horizontally around the copper wire.

4. The method for manufacturing a tinned copper wire according to claim 2, wherein the stripping portion is composed of a braided tube through which the copper wire is inserted.

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