Method for partially plating a cylindrical member

Abstract

To provide a method for plating a part of a reliable cylindrical member.SOLUTION: A method for plating a part of a cylindrical member, capable of plating an inner peripheral surface of the cylindrical member having an annular recessed part formed on the inner peripheral surface comprises the steps of: inserting the tip part of a protective bag having a balloon inserted from a communication opening communicated to the annular recessed part into the annular recess part; inflating the balloon inserted into the protective bag and closing the annular recessed part to tie the opening of the balloon; closing the communication opening; masking the entire cylindrical member with a masking resin; peeling the masking resin on the inner peripheral surface of the cylindrical member; and plating the inner peripheral surface of the cylindrical member after peeling the masking resin.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present application relates to a method for selectively plating a cylindrical member. [Background technology]

[0002] Conventionally, one method for applying partial plating is to cover the parts that do not need to be plated with a masking resin. However, when attempting to apply partial plating to a cylindrical member, if the internal shape of the cylindrical member is complex and the opening leading to the interior of the cylindrical member is small, there is a problem in that if the masking resin gets inside the cylindrical member, it becomes very difficult to remove the masking. Therefore, it is difficult to apply the method of masking the interior of a cylindrical member using only a resin masking.

[0003] To address the above problem, Patent Document 1 discloses a method in which a rubber masking member is press-fitted into the inner diameter of a cylindrical member to mask the portions of the inner surface of the cylindrical member that do not need to be plated, and then plating is performed in this state to plate the exposed portions of the inner surface of the cylindrical member.

[0004] When performing such partial plating, Ni plating is applied to the entire inner surface of the introduction pipe using electroless plating or electrolytic plating. A cylindrical rubber masking member is then press-fitted into the inner diameter of the introduction pipe. When the masking member is press-fitted into the introduction pipe, the outer surface of the masking member adheres closely to the inner surface of the introduction pipe, masking the adhered area and preventing the plating solution from penetrating. Au plating is then applied to the exposed portion of the inner surface of the introduction pipe using electrolytic Au plating. In this case, the masked area is not plated with Au, and only the sealing portion (soldered portion) of the inner surface of the introduction pipe is partially plated with Au. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-251889 Summary of the Invention [Problem to be solved by the invention]

[0006] The conventional partial plating method for cylindrical members described in Patent Document 1 described above involves masking the cylindrical members by pressing in a rubber masking member, which poses a problem in that masking is not possible without equipment for pressing in the rubber masking member.

[0007] Furthermore, a conventional method for partially plating a cylindrical component involves covering the parts that do not need to be plated with a masking resin. However, when attempting to partially plate a cylindrical component, the internal shape of the cylindrical component is complex, and the opening leading to the interior of the cylindrical component is small and inaccessible, making it extremely difficult to remove the masking if the masking resin gets inside the component. Therefore, there is a problem that the method of masking the interior of a cylindrical component using only a resin masking is difficult to apply.

[0008] The present application discloses a technique for solving the above-mentioned problems, and its purpose is to provide a method for partially plating a cylindrical member, which plates the inner surface of the cylindrical member while preventing the masking resin from entering the annular recess formed on the inner surface of the cylindrical member. [Means for solving the problem]

[0009] The method for selectively plating a cylindrical member disclosed in the present application includes the steps of: An internal cavity is formed between an inner peripheral surface formed inside a cylindrical member and penetrating in the axial direction and an outer surface of the cylindrical member, a part of the inner peripheral surface in the axial direction is open over the circumferential direction, and a communication opening is provided that communicates from the outer surface to the inner peripheral surface via the internal cavity. A method for selectively plating a cylindrical member, comprising the steps of: The aforementioned The tip of the protective bag with the balloon inserted through the communication opening Until the opening on the inner circumferential surface is covered and inflating the balloon inserted inside the protective bag. The boundary between the inner circumferential surface of the cylindrical member and the balloon is closed. a step of masking the entire cylindrical member with a masking resin; a step of peeling off the masking resin from the inner peripheral surface of the cylindrical member; and a step of plating the inner peripheral surface of the cylindrical member from which the masking resin has been peeled off. [Effects of the Invention]

[0010] According to the method for selectively plating a cylindrical member disclosed in the present application, the tip portion of a protective bag into which a balloon is inserted is plated. formed on the inner surface After being inserted into the annular recess, the balloon is inflated to close the annular recess, thereby providing a highly reliable method for partial plating of cylindrical members in which the masking resin does not penetrate into the annular recess. [Brief explanation of the drawings]

[0011] [Figure 1] 1A and 1B are perspective views showing a method for partially plating a cylindrical member according to embodiment 1, in which (a) is a perspective view of the cylindrical member before plating, (b) is a perspective cross-sectional view of the cylindrical member showing the portion that does not require masking with diagonal lines, and (c) is a cross-sectional view of the cylindrical member. [Figure 2] 1 is a cross-sectional view showing a cylindrical member according to a first embodiment. [Figure 3] 1A and 1B are cross-sectional views showing steps in a method for selectively plating a cylindrical member according to embodiment 1, in which (a) is a cross-sectional view showing a state in which a protective bag and a balloon have been inserted into an annular recess, and (b) is a cross-sectional view showing a state in which the balloon has been inflated to block the annular recess and mask the small opening. [Figure 4] 1A and 1B are cross-sectional views showing steps in a method for selectively plating a cylindrical member according to embodiment 1, in which (a) is a cross-sectional view showing a state in which the entire cylindrical member is masked with a masking resin, and (b) is a cross-sectional view showing a state in which the masking resin on the inner surface of the cylindrical member has been peeled off. [Figure 5] 1A and 1B are cross-sectional views showing steps in a method for selectively plating a cylindrical member according to embodiment 1, in which (a) is a cross-sectional view showing the state after plating has been applied to the inner surface of the cylindrical member, and (b) is a cross-sectional view showing the state after the masking resin on the cylindrical member has been peeled off and the protective bag and balloon have been removed. DETAILED DESCRIPTION OF THE INVENTION

[0012] Embodiment 1 A first embodiment of the present invention will be described below with reference to Figures 1 to 3, where the same or corresponding components and parts are designated by the same reference numerals in each figure. Figure 1 is a perspective view showing a method for selectively plating a cylindrical component according to the first embodiment, where (a) is a perspective view of the cylindrical component before plating, (b) is a perspective cross-sectional view of the cylindrical component with hatched areas indicating areas that do not require masking, and (c) is a cross-sectional view of the cylindrical component. Figure 2 is a cross-sectional view of a cylindrical component according to the first embodiment, where (a) is a cross-sectional view showing a circular cylindrical shape, and (b) is a cross-sectional view showing a circular, partially deformed cylindrical shape.

[0013] Fig. 3 is a cross-sectional view showing a process of the method for selectively plating a cylindrical member according to embodiment 1, where (a) is a cross-sectional view showing a state in which a protective bag and a balloon are inserted into the annular recess, and (b) is a cross-sectional view showing a state in which the balloon is inflated to close the annular recess and mask the small opening. Fig. 4 is a cross-sectional view showing a process of the method for selectively plating a cylindrical member according to embodiment 1, where (a) is a cross-sectional view showing a state in which the entire cylindrical member is masked with a masking resin, and (b) is a cross-sectional view showing a state in which the masking resin has been peeled off the inner surface of the cylindrical member. Fig. 5 is a cross-sectional view showing a process of the method for selectively plating a cylindrical member according to embodiment 1, where (a) is a cross-sectional view showing a state in which the inner surface of the cylindrical member has been plated, and (b) is a cross-sectional view showing a state in which the masking resin has been peeled off the cylindrical member and the protective bag and balloon have been removed.

[0014] In Figures 1 and 2, 1 denotes a cylindrical member made of, for example, an aluminum cast member having an inner circumferential surface 2 to be plated, 3 denotes a member opening of the cylindrical member 1, 4 denotes an annular recess formed, for example, near the center of the inner circumferential surface 2 of the cylindrical member 1, 5 denotes an internal cavity having a casting surface formed inside the cylindrical member 1, and 6 denotes a communicating opening formed from a small hole that communicates from the outer surface of the cylindrical member 1 to the annular recess 4.

[0015] The cylindrical member 1 can be applied to a cylindrical inner peripheral surface 7 shown in Fig. 2(a) or a cylindrical inner peripheral surface 8 that is a partially deformed circle shown in Fig. 2(b). The inner peripheral surface of the cylindrical member 1 does not need to be a perfect cylinder, and a structure in which the cylindrical inner peripheral surface 8 shown in Fig. 2(b) is applied to the inner peripheral surface 2 of the cylindrical member 1 will be described as an example.

[0016] A method for plating the inner circumferential surface 2 of the cylindrical member 1 with, for example, silver will be described with reference to Figures 3 to 5. In Figures 3 to 5, 9 denotes a rubber balloon, 10 denotes a protective bag made of, for example, fluororesin into which the balloon 9 is inserted, 11 denotes masking tape for closing the communication opening 6, 12 denotes masking resin, and 13 denotes a silver-plated layer applied to the inner circumferential surface 2 of the cylindrical member 1.

[0017] Here, the silver plating is applied to improve electrical conductivity. In a cast cylindrical member 1, if silver plating adheres to the internal cavity 5 of the cylindrical member 1, the silver plating may fall off during use of the product, causing a short circuit. Therefore, it is necessary to partially silver plate only the inner surface 2 of the cylindrical member 1.

[0018] To solve this problem, as shown in Figure 3, the inside of the cylindrical member 1 is masked using a balloon 9, a protective bag 10, and a masking resin 12, and the outside of the cylindrical member 1 is masked using the masking resin 12. This makes it possible to prevent the masking resin 12 or the chemical solution used in the plating process from penetrating into the inside of the cylindrical member 1.

[0019] When masking the parts that do not need to be plated, masking resin 12 and balloons 9 are used in combination, so that partial plating is performed only on the inner surface 2 of the cylindrical member 1 without the masking resin 12 penetrating into the interior of the cylindrical member 1.

[0020] A balloon 9 is placed in a protective bag 10 and inflated through the connecting opening 6 into the annular recess 4 of the cylindrical member 1, sealing the annular recess 4. The cylindrical member 1 is then immersed in liquid masking resin. The masking resin 12 is then removed from the area requiring plating, and plating is then performed. By covering the balloon 9 with the protective bag 10, the protective bag 10 does not dissolve when immersed in high-temperature masking resin during the masking process. Furthermore, the balloon 9 does not burst during the plating process, in which the cylindrical member 1 reacts in an acidic or basic plating solution. Therefore, there is no risk of the liquid masking resin or plating solution leaking into the interior of the cylindrical member 1 during the immersion in the masking resin 12 and plating process. The process steps are detailed below. While the protective bag 10 has been described as being made of, for example, a fluororesin, it is not limited to this material and can be any material that can protect the balloon 9 without dissolving or bursting.

[0021] As shown in Figure 3(a), a balloon 9 inserted into a protective bag 10 through the communication opening 6 is placed in the annular recess 4 of the cylindrical member 1. The tip portion 10a of the protective bag 10 is inserted into the annular recess 4. By covering the balloon 9 with the protective bag 10 made of fluororesin, the masking is maintained without the balloon 9 being dissolved by the high-temperature liquid masking resin or plating solution.

[0022] As shown in Figure 3(b), a balloon 9 is inflated inside the cylindrical member 1 using a balloon pump or the like. At this time, care is taken to ensure that no gaps are formed at the boundary between the inner circumferential surface 2 of the cylindrical member 1 and the balloon 9. This closes the annular recess 4 of the cylindrical member 1 with the balloon 9, preventing the masking resin from entering the annular recess 4 and the internal cavity 5 of the cylindrical member 1. After ensuring that the air in the balloon 9 does not leak out, the opening of the balloon 9 is tied with a rubber band. Thereafter, the communication opening 6 is sealed with masking tape 11. By sealing the communication opening 6 with masking tape 11, the masking resin is prevented from entering the interior of the cylindrical member 1.

[0023] As shown in FIG. 4(a), the entire cylindrical member 1 is immersed in a liquid masking resin bath, and masking resin 12 is applied to the surface of the cylindrical member 1 and the surface of the protective bag body 10.

[0024] As shown in FIG. 4(b), the masking resin 12 is removed only from the inner peripheral surface 2 of the cylindrical member 1, which is the portion that needs to be plated, to prepare for plating.

[0025] As shown in Figure 5(a), silver plating is applied to the inner circumferential surface 2 of the cylindrical member 1 to form a plating layer 13. After plating is complete, the masking resin 12 covering the cylindrical member 1 is peeled off, as shown in Figure 5(b). The masking tape 11 on the communication opening 6 is peeled off, and the balloon 9 inside the cylindrical member 1 is popped. The balloon 9 and protective bag 10 are removed from the inside of the cylindrical member 1 through the communication opening 6.

[0026] It is possible to accurately silver-plate only the inner peripheral surface 2 of the cylindrical member 1 using a simple method, without applying silver plating to the casting surface of the internal cavity 5 of the cylindrical member 1 made of aluminum casting. This reduces the cost of silver plating the cylindrical member 1. Also, by not plating the casting surface, which has poor adhesion to silver plating, there is no risk of the silver plating coming off after the product is shipped.

[0027] Although the above embodiment has been described taking an aluminum casting as an example, the present invention is not limited to this, and similar effects can be obtained with castings made of other materials such as iron or copper.

[0028] As described above, the portions of the inner surface 2 of the cylindrical member 1 that do not need to be plated can be masked by inflating the balloon 9 inside the cylindrical member 1, a method that does not rely on equipment. Furthermore, after plating is complete, the balloon 9 can be removed extremely easily by simply removing it from the inside of the cylindrical member 1. Furthermore, because masking is performed using the balloon 9 and masking resin 12, the cylindrical member 1 is not damaged when the masking resin is inserted or removed.

[0029] The annular recess 4 of the cylindrical member 1 is masked with a balloon 9, and then the entire cylindrical member 1 is masked with a masking resin 12. The masking resin 12 is then removed from the inner circumferential surface 2 of the cylindrical member 1, which is the portion requiring plating. The exposed portion of the inner circumferential surface 2 of the cylindrical member 1 is then subjected to partial electrolytic plating to form a plating layer 13. Therefore, no special equipment is required to mask the interior of the cylindrical member 1, and partial plating can be applied to the inner circumferential surface 2 of the cylindrical member 1 with high dimensional accuracy using a simple technique without removing the masking from the interior of the cylindrical member 1. During this process, the annular recess 4 masked with the balloon 9 and the surface layer of the cylindrical member 1 masked with the masking resin 12 are not plated, and only the inner circumferential surface 2 of the cylindrical member 1 is partially plated. Finally, the masking resin 12 is removed, and the balloon 9 and protective bag 10 are removed from the communicating opening 6 of the cylindrical member 1.

[0030] Therefore, after the tip portion of protective bag 10 with balloon 9 inserted therein is inserted into annular recess 4, balloon 9 is inflated to close annular recess 4, thereby providing a highly reliable partial plating method for a cylindrical member that prevents masking resin from entering annular recess 4. In this way, partial plating can be applied with high precision to inner circumferential surface 2 of cylindrical member 1, which has a complex internal shape, without compromising productivity.

[0031] Although the present application describes exemplary embodiments and examples, the various features, aspects, and functions described in one embodiment are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are conceivable within the scope of the technology disclosed in the present specification, including, for example, cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with components of another embodiment. [Industrial Applicability]

[0032] The present invention is suitable for realizing a highly reliable method for selectively plating a cylindrical member, which prevents the masking resin from entering the annular recess. [Explanation of symbols]

[0033] 1 cylindrical member, 2 inner peripheral surface, 4 annular recess, 5 internal cavity, 6 communicating opening, 9 balloon, 10 protective bag body, 11 masking tape, 12 masking resin, 13 plating layer

Claims

1. A method for partially plating a cylindrical member, wherein an internal cavity is formed between an inner peripheral surface formed inside the cylindrical member and penetrating in the axial direction and an outer surface of the cylindrical member, a portion of the inner peripheral surface in the axial direction is opened over the circumferential direction, and a communicating opening is provided that communicates from the outer surface to the inner peripheral surface via the internal cavity, a step of inserting a tip portion of the protective bag into which the balloon has been inserted through the communication opening until the tip portion covers the opening on the inner circumferential surface; a step of inflating the balloon inserted inside the protective bag to close the boundary between the inner circumferential surface of the cylindrical member and the balloon; a step of closing the communication opening; a step of masking the entire cylindrical member with a masking resin; peeling off the masking resin from the inner circumferential surface of the cylindrical member; plating the inner circumferential surface of the cylindrical member from which the masking resin has been removed; A method for selectively plating a cylindrical member, comprising:

2. 2. The method for selectively plating a cylindrical member according to claim 1, wherein the cylindrical member is an aluminum cast member, and the inner peripheral surface of the cylindrical member is selectively silver plated.

3. 3. A method for selectively plating a cylindrical member as described in claim 1 or claim 2, characterized in that after plating the inner surface of the cylindrical member, the masking portion of the cylindrical member is peeled off and the protective bag and the balloon are removed from the cylindrical member.

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