PLATING DEVICE
Disclosed is a plating device that has a plating tank that retains a plating fluid and carries out magnetic metal plating on a shaft shaped member immersed in the plating fluid as a negative electrode. The plating device is provided with: a plurality of shielding jigs that are fitted to the outer peripheral surface of the shaft shaped member and regulate the part of the shaft shaped member being plated; and a positive electrode provided in the vicinity of the shaft shaped member and having an output part that faces the part being plated. A center position in the axial direction of the shaft shaped member for the part being plated and a center position of the output part are aligned within a prescribed allowable value for the center positions.
The present invention relates to a plating device, for example a plating device for forming magnetostrictive films in a magnetostrictive torque sensor by a magnetic alloy plating process.
BACKGROUND ARTVehicles are commonly equipped with, for example, electrically-powered power steering devices. An electrically-powered power steering device generates assistive torque to reduce the steering torque needed to be produced in the steering system through operation of the steering wheel by the driver. By generating assistive torque, the electrically-powered power steering device can reduce the burden on the driver. An electrically-powered power steering device has a steering torque sensor for detecting steering torque; the torque sensor for detecting torque, such as steering torque, acting on a shaft-shaped member (also called a pivot, pinion shaft, or input shaft), can be constituted, for example, by a magnetostrictive torque sensor which utilizes magnetostrictive effect by a plurality of magnetostrictive films having mutually different magnetic anisotropy.
For example, Patent Literature 1 discloses a plating device employed for forming two magnetostrictive films by plating of a plated portion of a shaft-shaped member, doing so prior to imparting having mutually different magnetic anisotropy to the films. Due to the flow of current from the positive electrode (a metal cage or metal pellets) of the plating device to an exposed portion or non-masked portion (negative electrode, plated portion) of the shaft-shaped member, metal ions (e.g. Ni ions or Fe ions) present in the plating fluid are deposited on the negative electrode side, forming a magnetic alloy plating such as a magnetostrictive film or the like.
However, because the lines of current (lines of electrical force) lead towards the plated portion (negative electrode) from the entirety of the positive electrode, the lines of current are dependent upon the pattern, such as the length, of the positive electrode, and cannot flow uniformly into the plated portion. Stated another way, depending on the type of specifications required of an electrically-powered power steering device, it may be necessary for the lines of current to flow more uniformly into the plated portion. Specifically, in the plating device disclosed in the aforementioned Patent Literature 1, it is indicated to form the shielding jig at the center to a smaller diameter than the diameter of the shielding jigs above and below, to thereby establish a uniform current density distribution over the entire surface of the plated portion. However, the inventors have found that, in actual practice, the current density distribution over the surface of the plated portion in an axial direction of a shaft-shaped member will differ depending on the location of the plated portion, in a manner dependent upon the pattern of the positive electrode, and that variability of thickness of the magnetic alloy plating may not always be kept within the allowable range, depending on the type of specifications.
PRIOR ART LITERATURE Patent LiteraturePatent Literature 1: Japanese Patent Application Laid-Open
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- Publication No. 2008-101243
An object of the present invention is to provide a plating device whereby it is possible to more form a magnetic alloy plating to more uniform thickness.
Solution to ProblemAccording to a first aspect of the present invention, there is provided a plating device having a plating tank retaining a plating fluid, the device being used to carry out magnetic alloy plating of a shaft-shaped member immersed in the plating fluid, the shaft-shaped member serving as a negative electrode, wherein the plating device has a plurality of shielding jigs fitted about an outer peripheral surface of the shaft-shaped member and defining a plated portion on the shaft-shaped member, and a positive electrode disposed surrounding the shaft-shaped member, and having an output portion facing the plated portion. The center position of the plated portion and the center position of the output portion in the axial direction of the shaft-shaped member are aligned to within a predetermined tolerance relating to the center position.
In cases in which the center position of the plated portion of a shaft-shaped member and the center position of the output portion of the positive electrode are aligned in the axial direction of the shaft-shaped member, the lines of current flowing into the plated portion are symmetrical with respect to the center position of the plated portion. Consequently, despite variability of thickness of the magnetic alloy plating, by virtue of being symmetrical with respect to the center position of the plated portion, the magnetic alloy plating can be formed to more uniform thickness.
Stated another way, in cases in which the lines of current flowing into a plated portion are not symmetrical with respect to the center position of the plated portion, and moreover the thickness of the magnetic alloy plating is at its thickest or thinnest at a position furthest away from the center position of the plated portion (one end location of the plated portion), the difference between that thickness and the thickness of the magnetic alloy plating at the one end location of the plated portion will exceed the difference when the lines of current flowing into the plated portion are symmetrical with respect to the center position of the plated portion. Consequently, the variability of thickness of magnetic alloy plating observed when the lines of current flowing into the plated portion are not symmetrical with respect to the center position of the plated portion may fail to be kept within the allowable range at, for example, at one end location of the plated portion.
Accordingly, a magnetic alloy plating can be formed to more uniform thickness by aligning the center position of the plated portion of the shaft-shaped member and the center position of the output portion of the positive electrode to within an tolerance relating to center position, in order to keep the variability of thickness of magnetic alloy plating to within the allowable range throughout the entire plated portion.
In the first aspect, in preferred practice, the length of the plated portion and the length of the output portion of the positive electrode are aligned to within a predetermined tolerance relating to the length, in an axial direction of the shaft-shaped member.
In cases in which the length of the plated portion of the shaft-shaped member and the length of the output portion of the positive electrode are aligned in the axial direction of the shaft-shaped member, the lines of current flowing into the plated portion will be perpendicular to the plated portion surface. Consequently, the current density distribution will be uniform over the entire surface of the plated portion, allowing the magnetic alloy plating to be formed to more uniform thickness.
Consequently, by aligning the length of the plated portion of the shaft-shaped member and the length of the output portion of the positive electrode to within a predetermined tolerance relating to length such that variability of thickness of magnetic alloy plating is kept to within the allowable range throughout the entire plated portion, the magnetic alloy plating can be formed to more uniform thickness.
In the first aspect, in preferred practice, the plating device further has a shield disposed between the positive electrode and the shaft-shaped member.
The shield allows positive electrode output portions to be formed in portions of the positive electrode, instead of using the entire positive electrode as the output portion.
In the first aspect, in preferred practice, the pattern of the shield defines the pattern of the output portion of the positive electrode, the pattern of the shield being determined such that variability of thickness of the magnetic alloy plating is kept to within an allowable range.
Depending on the type of positive electrode, there may be instances in which the center position of the plated portion of the shaft-shaped member and the center position of the output portion of the positive electrode cannot be aligned. Or, depending on the type of positive electrode, there may be instances in which the lengths of the plated portion of the shaft-shaped member and the length of the output portion of the positive electrode cannot be aligned. Accordingly, the pattern (the center position and length) of the output portion of the positive electrode is adjusted through adjustment of the pattern of the shield, whereby the metallic alloy plating can be formed to more uniform thickness.
Moreover, depending on the type of shaft-shaped member, the pattern, such as the length, of the plated portion may differ. In such cases as well, with a single positive electrode, by adjusting the pattern of the shield, the metallic alloy plating can be formed to more uniform thickness while achieving compatibility with shaft-shaped members and plated portions of various different types.
In the first aspect, the shield is preferably of assembly type detachable from the positive electrode.
By making the shield replaceable, the metallic alloy plating can be formed to more uniform thickness, while achieving compatibility with shaft-shaped members and plated portions of various different types.
In the first aspect, in preferred practice, the plating device is further provided with a plating fluid spray nozzle having plating a fluid spray orifice facing the plated portion, the plating fluid spray nozzle being of assembly type detachable from the plating tank.
Depending on the type of shaft-shaped member, the patterns, such as the center positions, of the plated portions may differ. In such cases, by replacing the plating fluid spray nozzle having plating a fluid spray orifice which faces the plated portion, the metallic alloy plating can be formed to more uniform thickness while achieving compatibility with shaft-shaped members and plated portions of various different types.
In the first aspect, in preferred practice, the center position of the plated portion and the center position of the plating fluid spray orifice are aligned to within a tolerance relating to center position, in the axial direction of the shaft-shaped member.
In cases in which the center position of the plated portion of the shaft-shaped member and the center position of the plating fluid spray orifice (the output portion of the plating fluid nozzle) are aligned in the axial direction of the shaft-shaped member, the lines of flow of the plating fluid flowing to the plated portions will be symmetrical with respect to the center positions of the plated portions. Consequently, despite variability of thickness of magnetic alloy plating, there is symmetry with respect to the center positions of the plated portions, and the metallic alloy plating can be formed to more uniform thickness. Even in cases in which the shaft-shaped member is rotated to stir the plating fluid inside the plating tank, the metallic alloy plating can be formed to more uniform composition.
In the first aspect, in preferred practice, the length of the plated portion and the length of the plating fluid spray orifice are aligned to within a tolerance relating to the length, in an axial direction of the shaft-shaped member.
In cases in which the length of the plated portion of the shaft-shaped member and the length of the plating fluid spray orifices (the output portion of the plating fluid nozzle) are aligned in the axial direction of the shaft-shaped member, the density of the metal ions flowing to the plated portion will be uniform over the entirety of the plated portions. Consequently, the metallic alloy plating can be formed to more uniform thickness. Even in cases in which the shaft-shaped member is rotated to stir the plating fluid inside the plating tank, the metallic alloy plating can be formed to more uniform composition.
It will be readily apparent to a person skilled in the art that various modifications to the aspects according to the present invention shown herein by way of examples are possible without departing from the spirit of the invention.
Certain preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Persons skilled in the art should keep in mind that the present invention is not unduly limited to the embodiments described below.
EmbodimentsIn the example of
Referring to
Referring to
In the example of
In the example of
In the example of
The plating fluid 2 is an alloy plating fluid containing at least two species of metal ions (e.g., Ni ions and Fe ions) in prescribed proportions, and is maintained at predetermined temperature by the plating fluid regulating tank 4. The shield jigs 13, 14, 15, which are made, for example, of insulating resin, are installed about the outside peripheral surface of the shaft-shaped member 5. The shield jigs 13, 14, 15 are of disk shape, preferably 10 mm or larger in size for example, and are separable in diametrical directions, so as to enable attachment to and detachment from the shaft-shaped member 5. The diameter of the intermediate shield jig 14 situated between the shield jigs 13, 15 at either end is preferably formed to be smaller than the diameter of the shield jigs 13, 15 at either end; the intermediate shield jig 14 may be omitted as well.
The rotary retainer device 6 is provided with a rotary shaft 18 made of metal, furnished at a vertical orientation; a lifting/lowering mechanism 19 situated in an intermediate portion of the rotary shaft 18; a bearing 20 situated in a joined portion of the rotary shaft 18 and the lifting/lowering mechanism 19; the retainer member 12 situated at one end of the rotary shaft 18; a motor 21 situated at the other end of the rotary shaft 18; and a feeder brush 23 electrically connected to the negative pole of a power supply 22 situated in proximity to the motor 21. Through up and down motion of the rotary shaft 18 by the lifting/lowering mechanism 19, the rotary retainer device 6 is able to immerse the shaft-shaped member 5 in the plating fluid 2, or withdraw the shaft-shaped member 5 up and out from the plating fluid 2. The rotary retainer device 6 is constituted such that the shaft-shaped member 5 is rotated through rotation of the rotary shaft 18 by the motor 21.
The plating fluid regulating tank 4 is provided with a stirrer 29, a temperature regulator 30, and a heater 31; the plating fluid 2 is retained inside the plating fluid regulating tank 4. Through stirring of the plating fluid 2 by the stirrer 29, for example, the Ni ion and Fe ions in the plating fluid 2 can be uniformly dispersed, as well as producing uniform temperature throughout the plating fluid 2. The temperature regulator 30 measures the temperature of the plating fluid 2, and controls the heater 31 to maintain the plating fluid 2 at the prescribed temperature.
The plating fluid 2 within the plating fluid regulating tank 4 is supplied to the fluid chamber 7 interior via a plating fluid supply line 32 through which the plating fluid regulating tank 4 interior and the fluid chamber 7 interior communicate. A pump 33, a strainer 34, and a flow meter 35 are situated midway along the plating fluid supply line 32. A controller 36 for regulating the flow rate of the plating fluid 2 is also provided, the controller 36 being connected to the pump 33 via an inverter 37. The flow rate of the plating fluid 2 passing through the plating fluid supply line 32 is measured by the flow meter 35, and the controller 36 compares the measured value thereof to a preset value, and controls the inverter 37. Through regulation of the pump flow rate of the pump 33 by the inverter 37, the flow rate of the plating fluid 2 supplied to the fluid chamber 7 interior, i.e., the flow rate of the plating fluid 2 sprayed from the plating fluid spray orifices 26 (
In the example of
Depending on the type of shaft-shaped member 5, the position at which the plated portion 5s is situated on the shaft-shaped member 5 (the center position 5c) will differ; in the example of
As discussed below, by replacing the shield 10m, compatibility with shaft-shaped members 5 and plated portions 5s of various different types can be achieved in the same manner as with replacement of the plating fluid spray nozzles 9.
In the example of
When the power supply 22 is ON, the plating fluid 2 is sprayed from the plating fluid spray orifices 26 towards the plated portion 5s of the rotating shaft-shaped member 5. In so doing, the plating fluid 2 is supplied to the entire surface of the plated portion 5s, and uniform flow can be obtained over the entire surface of the plated portion 5s. Because the shaft-shaped member 5 rotates, the concentration of Ni ions and the concentration of Fe ions in the plating fluid 2 are maintained at constant levels over the entire surface of the plated portion 5s.
In the example of
In the example of
Even when the Ni ions and the Fe ions in the plating fluid 2 are consumed in the course of carrying out Ni—Fe alloy plating, Ni ions and Fe ions dissolve into the plating fluid 2 from the metal pellets 28 through electrolysis, and maintain the concentration of Ni ions and the concentration of Fe ions in the plating fluid 2 at constant levels, whereby the plating fluid 2 can be easily managed. Because the constitution in one in which the metal pellets 28 are contained within the metal cage 27, the metal cage 27 can be easily supplied with the metal pellets 28, even during the plating process.
In the example of
In the example of
In the example of
The metal cage 27 can be fastened to the plating tank 3 of
In cases in which the metal cage 27 and the shield 10m of
Rather than fastening the shield 10m, 10m of
In the case of application of the shield 10m, 10m of
In each of
Likewise, it is acceptable for the length 5l of the plated portion 5s to be longer that the length 10l of the output portion 10s; for the two to be perfectly aligned; or for the length 5l of the plated portion 5s to be slightly shorter than the length 10l of the output portion 10s, provided that the length 5l of the plated portion 5s (or the lengths 5l, 5l2) and length 10l of the output portion 10s of the positive electrode 10 (or the lengths 10l1, 10l2) are aligned within the prescribed tolerance relating to length, such that the variability of thickness of the magnetic alloy film is maintained within the acceptable range throughout the entire plated portion 5s.
It is preferable to take into consideration the iron composition, not just the film thickness, whereby the center position 5c of the plated portion 5s (or the center positions 5c1, 5c2) and the center position 10c of the positive electrode 10 (or the center positions 10c1, 10c2) can be aligned within the prescribed tolerance relating to center position (
The present invention is not limited to the exemplary embodiments set forth hereinabove, and a person skilled in the art may easily make modifications to o the exemplary embodiments set forth hereinabove, within the technical scope encompassed by the claims.
REFERENCE SIGNS LIST
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- O: origin
- 1: plating device
- 2: plating fluid
- 3: plating tank
- 5: shaft-shaped member
- 5c: center position of plated portion
- 5l: length of plated portion
- 5s: plated portion
- 6: rotary means
- 9: plating fluid spray nozzle
- 9b, 9f: plating fluid spray nozzle fasteners
- 10: positive electrode
- 10b, 10n, 10f1: shield fasteners
- 10c: center position of output portion
- 10l: length of output portion
- 10f2: metal cage fastener
- 10m: shield
- 10s: output portion
- 13, 15: shield jigs at either end
- 14: shield jig situated between shield jigs at either end
- 26: plating fluid spray orifices
- 26c center position of plating fluid spray orifice
- 27 metal cage
- 28 metal pellets
Claims
1. A plating device comprising a plating tank retaining a plating fluid, the device being used to carry out magnetic alloy plating of a shaft-shaped member immersed in the plating fluid, the shaft-shaped member serving as a negative electrode, wherein the plating device includes
- a plurality of shielding jigs fitted about an outer peripheral surface of the shaft-shaped member and defining a plated portion on the shaft-shaped member; and
- a positive electrode disposed surrounding the shaft-shaped member, and having an output portion facing the plated portion;
- characterized in that the center position of the plated portion and the center position of the output portion in the axial direction of the shaft-shaped member are aligned to within a predetermined tolerance relating to the center position.
2. The plating device of claim 1, wherein a length of the plated portion and a length of the output portion of the positive electrode are aligned to within a predetermined tolerance relating to the length, in an axial direction of the shaft-shaped member.
3. The plating device of claim 1, further comprising a shield disposed between the positive electrode and the shaft-shaped member.
4. The plating device of claim 3, wherein a pattern of the shield defines a pattern of the output portion of the positive electrode, the pattern of the shield being determined such that variability of thickness of the magnetic alloy plating is kept to within an allowable range.
5. The plating device of claim 3, wherein the shield is of assembly type detachable from the positive electrode.
6. The plating device of claim 1, further comprising a plating fluid spray nozzle having a plating fluid spray orifice facing the plated portion, the plating fluid spray nozzle being of assembly type detachable from the plating tank.
7. The plating device of claim 6, wherein the center position of the plated portion and the center position of the plating fluid spray orifice are aligned to within an tolerance relating to the center position, in the axial direction of the shaft-shaped member.
8. The plating device of claim 7, wherein the length of the plated portion and the length of the plating fluid spray orifice are aligned to within a prescribed tolerance relating to the length, in the axial direction of the shaft-shaped member.
9. The plating device of claim 2, further comprising a shield disposed between the positive electrode and the shaft-shaped member.
10. The plating device of claim 4, wherein the shield is of assembly type detachable from the positive electrode.
11. The plating device of claim 2, further comprising a plating fluid spray nozzle having a plating fluid spray orifice facing the plated portion, the plating fluid spray nozzle being of assembly type detachable from the plating tank.
12. The plating device of claim 3, further comprising a plating fluid spray nozzle having a plating fluid spray orifice facing the plated portion, the plating fluid spray nozzle being of assembly type detachable from the plating tank.
13. The plating device of claim 4, further comprising a plating fluid spray nozzle having a plating fluid spray orifice facing the plated portion, the plating fluid spray nozzle being of assembly type detachable from the plating tank.
14. The plating device of claim 5, further comprising a plating fluid spray nozzle having a plating fluid spray orifice facing the plated portion, the plating fluid spray nozzle being of assembly type detachable from the plating tank.
Type: Application
Filed: Dec 21, 2012
Publication Date: Nov 20, 2014
Inventors: Yutaka Arimura (Wako-shi), Yasuo Shimizu (Wako-shi), Atsuhiko Yoneda (Wako-shi)
Application Number: 14/371,638
International Classification: C25D 21/12 (20060101); C25D 3/56 (20060101); C25D 17/06 (20060101);