JPH10330989A - Rotary galvanizing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply plating of a uniform and sufficient thickness on the inner side of cup-shaped cases as well. SOLUTION: This plating device has a bar-shaped cathode 3 disposed freely turnably horizontally in a plating cell 1 and hooking jigs 6 which are arranged radially orthogonally with the axial line of this cathode 3 on the outer peripheral of a bearing part fitted to the cathode 3 and have work mounting parts having forked front ends and hold works 4 by the spring pressures thereof. The hooking jigs 6 are immersed into a plating liquid in such a manner that the works 4 mounted at least to the one work mounting parts emerges from the plating liquid. The works 4 mounted at the hooking jigs 6 are rationally moved in the plating liquid by rotating the cathode 3, by which the plating liquid is discharged from the works 4 once every time the works 4 emerge into the air from the plating liquid at every one turn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electrogalvanization, and more particularly to a plating method for plating on a cup-shaped case so as to provide even plating by rotating the case.

[0002]

2. Description of the Related Art In electroplating, a work (item to be plated) is immersed in an aqueous solution containing metal ions, and a direct current is applied between the work and a suitable soluble or insoluble anode as a cathode to form a metal on the surface of the work. Of the film is electrolytically deposited. As plating by the immersion method, there are (a) a static plating method and (b) a barrel plating method. The static plating method of (a) is a method which is usually performed, in which a work is hooked on a hooking jig and suspended and immersed in a plating bath.
The barrel plating method of (b) is a method used for plating small items such as screws and washers. A work is put in a barrel, and the barrel is immersed in a plating solution and rotated. There is a tilting rotary plating method in which a work is directly put into the container and the tall bath is rotated to perform plating.

As a plating method for a cup-shaped case as a work, a static plating method is generally used. The work is mounted on a hooking jig as shown in FIG. 4 and immersed in a plating solution to be connected to a cathode. The plating is performed in a stationary state. This hooking jig has a bar-shaped hooking portion 41 having one end formed in a key shape, and is disposed at an appropriate interval so as to be orthogonal to the hooking portion 41, and has a forked tip, and holds the case by its spring pressure. It comprises a rib 44 provided with a work mounting portion 42. Reference numeral 43 denotes an insulating portion for preventing plating on portions other than required portions. To do this,
When rotating plating is performed in a barrel or barrel bath using the barrel plating method, workpieces may collide with each other and be damaged, or even plating may not be obtained because an appropriate current does not flow inside the case. To do that.

However, when plating is performed by this static plating method, uniform plating can be obtained on the outside of the work.
There is a problem that a plating having a uniform and sufficient thickness cannot be obtained inside the work. The reason why uniform plating cannot be obtained is that the water in the plating solution is immersed in the plating solution out of the hydrogen gas generated when electrolysis is performed by energizing the electroplating and the air inside the work before immersion It is considered that a portion of the air that has not been completely exhausted sometimes covers the inside of the work unevenly.

[0005] Further, the reason that plating having a sufficient thickness cannot be obtained is that the plating solution inside the work is almost in a stagnant state, and cannot be sufficiently exchanged with a solution containing new metal ions. It is considered that the replenishment of water is not sufficiently performed. That is, the well-known metal deposition process is hindered by the accumulation of air and hydrogen gas and the shortage of metal ions. Currently, in order to solve such a problem, the hooking jig is forcibly moved to reduce hydrogen gas or hydrogen gas as much as possible. The air is evacuated, and the plating solution remaining inside is replaced.

[0006]

However, in the method of forcibly moving the hooking jig, the work is detached from the hooking jig when it is strongly moved, or an appropriate plating film formation process is hindered depending on the way of moving. In order to solve this disadvantage, after plating, perform a secondary processing to protect the inside of the work by painting or coating, or put an auxiliary electrode on each work to uniformly metalize inside the work. Is deposited.
However, performing a secondary processing or attaching an auxiliary electrode requires an extra step.
In particular, the plating work for attaching the auxiliary electrode is a factor of high cost, and is usually avoided. The present invention has been made in order to solve the above-mentioned problems, and a rotating galvanizing method capable of applying plating having a uniform and sufficient thickness to the inside, and achieving this with high productivity. The purpose is to provide.

[0007]

SUMMARY OF THE INVENTION The present invention provides a method for rotary galvanizing, comprising:
A rod-shaped cathode provided horizontally and rotatably in a plating tank, and a bearing portion fitted around the cathode, radially arranged perpendicularly to the axis of the cathode, and the tip becomes a forked shape, and the spring pressure is used for the tip. A hooking jig provided with a work mounting portion for holding a case, wherein the hooking jig is immersed in a plating solution so that the case attached to at least one of the work mounting portions comes out of the plating solution; By rotating the case attached to the hooking jig by rotating the plating solution in the plating solution, the plating solution is discharged from the case once each time the case comes out of the plating solution into the air once per rotation. It is characterized by doing.

Here, the rotation speed is 5 to 7 rotations / minute, and the plating bath composition is 29 to 30 g / zinc metal.
Liter, sodium cyanide 60-70 g /
Liter and a mixture of 1 g / liter or less of sodium sulfide, and the M ratio (sodium cyanide (g /
Liter) / metal zinc in liquid (g / liter) 2.2
The composition is characterized by having a bath composition of ~ 2.4.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In an embodiment of the present invention, in a galvanizing method using a cup-shaped case as a work, a rod-shaped cathode provided horizontally and rotatably in a plating tank is fitted with the cathode. The outer periphery of the bearing portion is provided with a hooking jig provided radially perpendicular to the axis of the cathode and having a bifurcated tip and having a work mounting portion for holding the case by its spring pressure, and at least one work mounting jig. The hooking jig is immersed in the plating solution so that the case attached to the portion comes out of the plating solution, and the case attached to the hooking jig is rotated in the plating solution by rotating the cathode. By doing so, the plating process is performed such that the case exchanges the plating solution inside the work once per rotation.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A rotary galvanizing method according to the present invention will be described.
This will be described below with reference to FIGS. FIG. 1 is a longitudinal sectional front view of a main part showing an arrangement of electrode plates when performing electroplating by a plating apparatus using the rotary galvanizing method of the present invention.
1 is a longitudinal sectional view showing a shape of a hooking jig according to the present invention. In FIG. 1, 1 is a plating tank, 2 is an anode, 3 is a cathode, 4 is a work, 5 is a plating solution, and 6 is a hooking jig. The plating solution 5 is set so that at least one work 4 comes out of the plating solution when the hooking jig 6 is immersed. Further, the cathode 3 is rotatable by a rotation driving device (not shown) capable of freely setting a rotation speed,
It is also provided vertically.

In FIG. 2, a hooking jig 6 includes a bearing 61 fitted to the cathode 3, and
The workpiece mounting portion 62 is arranged radially perpendicular to the axis of
Of the cartilage 64 provided with The bearing 61 is made of copper, and the ribs 64 are made of spring brass. For example, urethane coating is applied to unnecessary portions other than the inside of the bearing 61 with the cathode 3 and the work mounting portion 62 so as to prevent unnecessary plating. , Insulated. 63 is this urethane coating part. The hook jig 6 was fitted and fixed to the cathode 3, and was rotatable at the same time as the cathode 3.

Next, taking as an example a cup-shaped case made of steel (SPCC) as shown in FIG. 3 as a work, a method of galvanizing using such a plating apparatus will be described. . 3A is a longitudinal sectional view of the case, and FIG. 3B is a perspective view.

The bath composition of the zinc plating solution is suitable for a plating environment in which metal ions are precipitated while rotating the work 4 and the work is brought into contact with the outside air once during one rotation while rotating. 60 g / liter of zinc cyanide (the amount of zinc metal = 6)
0 × 0.48 = 29 g / l), sodium cyanide 65 g / l, sodium hydroxide 75 g / l, sodium sulfide 0.1 g / l, M ratio (sodium cyanide (g / l) in liquid / liquid) The plating solution was 2.25 of zinc metal (g / liter).

First, the work 4 was subjected to alkali degreasing, pickling, and electrolytic degreasing, which are conventional methods of pretreatment for zinc plating. Next, the work 4 thus pretreated is attached to the mounting portion 62.
The hooking jig 6 was fitted and fixed to the cathode 3, immersed in the plating solution 5 by the above-mentioned rotary driving device, and plated at a predetermined voltage, temperature and time while rotating. The rotation speed of the hooking jig 6 during this plating process was set to 7 rotations / minute, and the jig 6 was continuously rotated without interruption during the plating process.

The rotation speed of 7 revolutions / minute was experimentally obtained by changing the rotation speed in various ways, and the experimental results are shown in Table 1.

[Table 1] As shown in Table 1, the best plating film was obtained at 5 to 7 rotations / minute, and defects were found at 4 rotations / minute or less and at 8 rotations / minute or more.

As described above, since the work 4 is rotated at an appropriate rotation speed, the work 4 always moves with respect to the anodes 2 and 2, and plating work inside the work 4 is prevented. It became possible to improve. In addition, by rotating, the above-mentioned stagnation of hydrogen gas and air can be eliminated. Also, the plating solution inside the work 4 is discharged by putting the work 4 into the air once per rotation, and the plating solution is re-exposed. Since a new plating solution was always taken into the work 4 when it was immersed in 5, the plating having a uniform and sufficient thickness of the plating film became possible.

[0017]

According to the present invention, as described above,
In electrogalvanizing with a cup-shaped case as a work, a bar-shaped cathode provided horizontally and rotatably in a plating tank, and radially arranged perpendicular to the axis of the cathode on the outer periphery of a bearing part fitted with this cathode And the tip becomes bifurcated,
A hooking jig provided with a work mounting portion for holding the case by the spring pressure is provided, and the hooking jig is put into the plating solution so that the case attached to at least one of the work mounting portions comes out of the plating solution. By immersing, rotating the cathode, rotating the case attached to the hooking jig in the plating solution so that the case exchanges the plating solution inside the work once per rotation. Plating treatment is performed. After plating, secondary processing is performed to protect the inside of the work by painting or coating, or an auxiliary electrode is inserted into each work to uniformly deposit metal inside the work. It is possible to provide a rotary galvanizing method that can obtain high quality and high productivity with a simple configuration without the necessity of taking a method of precipitation. The ability.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of an essential part showing an arrangement of electrode plates when electrolytic plating is performed by a plating apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a shape of a hooking jig according to the present invention.

FIG. 3 is an external view of a cup-shaped case serving as a work.

FIG. 4 is a longitudinal sectional view of a conventional hooking jig.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plating tank 2 Anode 3 Cathode 4 Work 5 Plating solution 6 Hook jig 61 Bearing part 62 Work attaching part 63 Urethane coating 64 Branch bone

Claims (2)

[Claims] In a galvanizing of a cup-shaped case, a rod-shaped cathode horizontally and rotatably provided in a plating tank, and a radially orthogonal to an axis of the cathode are provided on an outer periphery of a bearing portion fitted to the cathode. And a hook jig provided with a work mounting portion for holding the case by its spring pressure, wherein the case attached to at least one of the work mounting portions comes out of the plating solution. The hooking jig is immersed in the plating solution as described above, and the case attached to the hooking jig is rotated in the plating solution by rotating the cathode, so that the case is once rotated once in the plating solution. A galvanizing method, wherein the plating solution is discharged from the case once each time the plating solution comes out into the air. 2. The rotation speed is 5 to 7 rotations / minute. The plating bath composition contains 29 to 30 g / liter of zinc metal, and 60 to 70 g / liter of sodium cyanide and 1 g / liter or less of sodium sulfide. In the mixed solution, the M ratio (sodium cyanide (g / liter) in the solution)
2. The method according to claim 1, wherein the bath composition is 2.2 to 2.4 / (metal zinc in liquid (g / liter)).