JPS5943896A - Method and device for plating on inside surface of metallic object - Google Patents

Abstract

PURPOSE:To plate satisfactorily the inside and outside surfaces of a metallic object in one stage in the stage of plating the metallic object having a deep inside surface, by inserting auxiliary electrodes to the inside surface of the metallic object in addition to anodes provided in a plating cell. CONSTITUTION:A hanger 12 is immersed in a plating cell 11, and anodes 13 are disposed on both sides of the cell 11. The hanger 12 consists of a cathode 121 and an anode 122, and the cathode 121 is connected to a metallic product 4 through plural holding bodies 14 at least one of which consists of a spring body. The product 4 is kept at a minus polarity. The anode 122 is connected to an auxiliary anode 15 which is disposed in the product 4. If the shape of the product 4 consists of a combination of two cup shapes, 2 or >=2 pieces of the anodes 15 are provided. If the product 4 is plated in the above-mentioned way, said product is plated evenly to the deep inside surface thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for plating the inner surface of a metal object having a deep inner surface, such as a pot-shaped metal object.

In the conventional Zn plating method and apparatus, for example, as shown in FIG. 1, an anode 2 made of a Zn plate is disposed at one end or both ends of a plating bath 1, and a metal product 4 to be plated is suspended from a hanger 3 of the cathode. I was doing plating.

However, in the above method, when the product 4 to be plated is in the shape of a pot, the inner surface is deep, so the plating near the bottom of the inner surface is insufficient, and the plating layer becomes uneven.

The present invention aims to improve the above-mentioned drawbacks and provide a plating method and apparatus that can perform good inner plating even on metal objects having deep inner surfaces.

This will be explained in detail below using figures.

In order to improve the drawbacks shown in FIG. 1, it has been proposed to separately perform internal plating as shown in FIG. That is, the metal product 4 whose outer surface has been plated is immersed in a plating bath 5, and the anode 6 made of a Zn plate is inserted into the inner surface of the metal product 4 to perform plating.

The disadvantages of the above method are that the number of steps is large, the plating of the inner and outer surfaces is done in separate processes, so the plating layer lacks homogeneity, and there is a risk of contact between the anode 6 and the metal product 4, resulting in poor workability. It was bad.

Therefore, the inventors of the present invention proposed a method and apparatus as shown in FIG. 3 (r) to enable complete plating of the inner and outer surfaces in just one plating step.

1 on the inner surface of the temporarily plated metal product 4, referring to Figure 3.
A plurality of auxiliary anodes 7 are provided and immersed in the coating tank 5. Then, the outer surface Q of the metal product 4 is directly plated by the anode 8 made of a Zn plate, and the inner surface is plated with ionized Zn ions from the anode 8 by the current from the auxiliary anode 7.

Therefore, it has been found that according to the method and apparatus shown in FIG. 3, the plating on the inner and outer surfaces can be uniformly performed in -times of the plating process.

However, the method and apparatus shown in FIG. 3 have some drawbacks in the following points.

Since the ++O auxiliary anode 7 wears out, it is difficult to use it for a long period of time.

Since there is a risk that the auxiliary anode 7 and the metal product 4 may come into contact with each other, the installation must be done carefully, resulting in poor workability.

In order to improve the above drawbacks, the present invention has the following configuration.

FIG. 4 is a schematic cross-sectional view of one embodiment of the present invention.

A hanger 12 is immersed in the plating bath 11. Anodes 13 made of Zn are located on both sides (front and back in the figure) of the plating tank 11.
are arranged, and a metal product 4 is held in the nozzle 12. The hanger 12 consists of a cathode 121 and a 6i122. communicates with the metal product 4 to make the polarity of the metal product negative. Therefore, one end of the holder 14 for holding the metal product 4 is in contact with the cathode 12□, and the other end is in contact with the metal product 4. The holding body 14 is a metal product 4
It is inserted into the inner surface of the holder 14 and comes into contact with the metal product 4, thereby holding the metal product 4. This holding work is difficult because a part of the holder 14 becomes spring-like and deforms. , at least one of which is made of a spring body.

The anode 12□ is connected to an auxiliary anode 15, and the auxiliary anode 15 is arranged on the inner surface of the metal product 4.

The number of auxiliary anodes 15 may be one or more, and when the shape of the metal product 4 consists of a combination of two pot-like objects as in the illustrated embodiment, or when it has a special shape, There may also be 21 or more.

Note that the number of metal products 4 installed on the hanger 12 is arbitrary. Further, the cathode 12□ and the anode 122 of the hanger 12 are not coated with insulation except where necessary.

Below, regarding the auxiliary anode 15, (a) and (b) in Fig. 5 are shown.
Explain with reference to.

The auxiliary anode 15 is shown in FIG.
5 has two contact prevention rings 17 fitted therein. The contact prevention ring 17 is made of an insulating type synthetic resin, such as Teflon or nylon (if necessary). Contact prevention ring 17 is '>i11 auxiliary anode 15
The structure is such that it covers as much as possible, and the tip of the auxiliary anode 15 also extends and has a shape.

As shown in FIG. 6, the contact prevention ring 17 has one or more notches 18 formed on its outer periphery to improve the electric field between the auxiliary anode 15 and a metal product (not shown). In the above, the number of contact prevention rings 170 may be one or more.

The structure shown in (b) is another embodiment of the auxiliary anode 15,
A screw 16 is provided at the end of the auxiliary anode 15, and it is screwed into the anode 122 of the hanger and can be replaced at will, which is the same as in (a), but the thickness of the contact prevention ring 171 is reduced by using a thin comb and a notch. The setting is not here. In this embodiment, the contact prevention ring 17. The surface area of the auxiliary anode 15 that comes into contact with the bath liquid increases as the anode becomes thinner, but this also has the disadvantage of making it easier to rub against metal products. In order to improve this drawback even a little, contact prevention rings 17. It is desirable to provide a Further, in this embodiment, the anode 122 of the hanger is divided into two parts, and an auxiliary anode 15 is provided on each part.

As explained above, according to the present invention, even the deep inner surface of a pot-like metal product can be plated evenly in just one process, and costs and production equipment can be significantly reduced. .

Furthermore, if a part of the holder is a spring body, it is not only possible to attach a metal product to the hanger, but also because the holder conducts electricity and uses the metal product as a cathode, which simplifies the structure of the holder. ,
Lighter.

Furthermore, the structure in which the auxiliary anode is detachably attached makes it easy to replace the auxiliary anode before it wears out.

For those equipped with a contact prevention ring, does the contact prevention ring have a cutout, which would make it easier to attach metal products to the nozzle? With this, the electric field can be made good, thereby reducing plating unevenness.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing Kokyo's plating method and equipment, Figure 2
The figure is a schematic diagram showing an example of inner surface plating, FIG. 3 is a schematic diagram showing an embodiment of the present invention, FIG. 4 is a schematic diagram showing a good embodiment of the present invention, and FIGS. ) is a cross section showing an embodiment of the auxiliary anode of the present invention, and FIG. 6 is a perspective view showing an example of a contact prevention ring. Agent Patent Attorney Tsuji San Department Figure 5 (0) (Figure 3 = 55 (

Claims (2)

[Claims] (1) In a method of plating a metal object having a deep inner surface,
A method in which an auxiliary anode is inserted into the inner surface of a metal object in addition to the anode provided in the plating bath, and the inner surface of the metal object is plated. (2) In an apparatus for plating a metal object having a deep inner surface, a noon guard that holds the metal object and the hanger are separated from the cathode and the anode, and the anode of the hanger protrudes toward the inner surface of the metal object and serves as an auxiliary anode. Equipment for plating the inner surface of metal objects made of