JPS6034636B2 - Method and device for preventing plating from turning in electric plating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electroplating, and more particularly, to prevention of plating from turning around in electroplating, which prevents plating from being applied to the back side of an object to be plated during electroplating. METHODS AND APPARATUS.

Electroplating is carried out by placing the object to be plated as a cathode in an electrolytic solution, making an anode in the electrolytic solution made of the metal to be plated, and passing a direct current through the object.

For example, in a half-split plain bearing used as a bearing for an internal combustion engine, lead plating is applied to the inner surface of the sliding bearing as an overlay. Care must be taken to ensure that this is not the case. For this reason, in the past, the inner surface of the slide bearing and the anode were made to face each other to facilitate plating on the inner surface, and at the same time, the electrolyte that had flowed to the back side of the slide bearing was blocked as much as possible from the electrolyte on the inner surface to prevent the current from sliding. This prevents the plating from going around to the back surface of the bearing, and prevents plating from being applied to the back surface of the sliding bearing. However, considering the process involved in mass production and the fact that some sliding bearings have oil holes that penetrate the inner and back surfaces, it is necessary to prevent the electrolyte from going around to the back side of the sliding bearing. However, it is virtually impossible to completely block the electrolyte that has gone around to the back side and the electrolyte on the plated side.
For this reason, it was necessary to remove the plating applied to the back surface by buffing or the like. In view of these points, the present invention is designed to perform normal electroplating on the object to be plated, by placing a back-turn prevention electrode on the back side of the object while applying a potential to the same machine. By applying a potential between the deposition potential and the elution potential when the potential of the plated object is taken as a reference potential between the back-turn prevention electrode and the reverse side prevention electrode, plating is prevented from being applied to the back surface of the object to be plated. The present invention provides a method and apparatus for achieving the same.

The present invention will be described below with reference to the illustrated embodiments. In FIGS. 1 and 2, 1 is a plating tank, 2 is an electrolytic solution, 3 is an anode, and 4 is a frame housing a half-split plain bearing 6 as an object to be plated. The pedestal 4 includes a box-shaped main body 6 and a support base 7 housed within the main body.

The support stand 7 has a substantially trapezoidal groove 8 extending perpendicularly to the plane of the drawing on the left side surface of FIG. is installed. Rod-shaped permanent magnets 10 are inserted and fixed into each of the pipes 9, so that the slide bearings 5 can be attracted to the pair of pipes 9 by the magnets 10. The support stand 7 is biased in the direction of FIG. It is held on the inner surface of the front plate 6a.

This front plate 6a has a boopa-shaped opening 1 whose outside is widened.
2 is formed along the longitudinal direction of the groove 8, and this gate 12 is formed along the longitudinal direction of the groove 8.
is opposed to the anode 3, so that the inner surface 5a, which is the plated surface of the sliding bearing 5 held in the main body 6 via the closure 12, is opposed to the anode 3. Further, the green portion 12a of the open row 2 on the support stand 7 side is made to protrude slightly inward along the contour of the opening 12, so that each of the current paths between the inner surface 5a of the sliding bearing 5 as a cathode and the anode 3 is The distances are made approximately equal in each portion of the inner surface 5a, thereby making it possible to form a uniform plating tank. Further, the pair of stainless steel pipes 9 are connected to the negative side of the first DC power source 14 via a conductive wire 13,
The positive side of the DC power supply 14 is connected to the anode 3 via a conductive wire 15.

Therefore, the current flows from the positive side of the DC power supply 14 to the conductive wire 15,
It flows to the negative side of the DC power supply 14 via the anode 3, the electrolytic solution 2, the sliding bearing 5, the pipe 9 and the conductive wire 13, and the inner surface 5a of the sliding bearing 5 is plated as is conventionally known.
However, in this embodiment, in order to prevent the back surface 5b of the slide bearing 5 from being plated, a conductive wire 16 is provided as an electrode to prevent reverse rotation, facing the back surface 5b. .

This conductive wire 16 is arranged and fixed along the bottom center and both sides of a groove 8 formed in the support base 7, and is connected to the negative side of the second DC power supply 18 via the conductive wire 17. is connected to. Further, the positive side of this DC power supply 18 is connected to the conductive wire 1
Connected to 3. In the above configuration, the DC power supply 18
It is clear that electroplating can be applied to the inner surface 5a of the sliding bearing 5 if an optimum value of current is caused to flow from the DC power supply 14 in consideration of the above.

On the other hand, the potential of the DC power supply 18 is set as follows. That is, FIG. 3 shows the relationship between the potential of the back surface 5b of the plain bearing 5 with respect to a certain reference electrode and the current between the conductive wire 16 and the back surface 5b of the plain bearing 5. In the figure, point A is the potential If it is less than that, the sliding bearing 5
Point B indicates the point where the back surface 5b of the plain bearing 5 is plated, and point B indicates the point where the back surface 5b of the plain bearing 5 becomes severely melted, which adversely affects bearing performance. Therefore, it is sufficient to apply a potential between points A and B to the hair circumference prevention electrode 16, thereby effectively preventing the back surface of the sliding bearing 5 from being plated.
In addition, in the relationship between the DC power supplies 14 and 18, the DC electric wire 18
The potential difference is smaller than that of the DC power supply 14, for example, 1/5 to
It is preferable to have a base angle of 1'15. More specifically, FIGS. 4a to 4d show the relative relationship between the potentials of the anode 3, the sliding bearing 5, and the conductive wire 16 as an electrode for preventing backtracking, and the relationship between the potentials of the anode 3, the sliding bearing 5, and the conductive wire 16 as an electrode for preventing backtracking. conductive wire 1
6, that is, a specific method of setting the potential difference of the DC power supply 18. First, as shown in Fig. 4a, if the anode 3 is connected to the positive side of the DC power supply 14, and the inner surface 5a of the sliding bearing 5 is connected to the negative side of the DC power supply 14, facing the anode 3, as shown in Fig. 4b. Absolute potential OV of electrolyte 2
On the other hand, the anode 3 has a positive potential V, and the inner surface 5a of the sliding bearing 5 has a negative potential V2, and the inner surface 5a is plated.

Therefore, it is possible to prevent the back surface 5b of the slide bearing 5 from being plated. As shown in FIG. 5 to the positive side of the DC power source 18 and the conductive wire 16 to the negative side of the DC power source 18, and applying a potential opposite to the potential applied during plating of the inner surface 5a to the sliding bearing 5, as shown in FIG. As shown in b, the potential of the conductive wire 16 becomes a potential V3 lower than the potential V2 of the plain bearing 5, and the back surface 5 of the plain bearing 5
It is possible to prevent plating from being applied to b.

Here, regarding the description of the potential applied to the conductive wire 16, that is, the specific setting of the potential difference of the DC power supply 18, the relative relationship will be explained in detail with reference to FIG. 3, as shown in FIG. 4c. When the DC power supply 18 is a variable DC power supply, the potential of the conductive wire 16 is set to point A in FIG.
Plating deposition potential), that is, the potential difference of the DC power supply 18 is V
If it is set above ^, the back surface 5b of the sliding bearing 5 will be plated, and on the other hand, if the point B (elution potential) in FIG. This will have a negative impact on
Therefore, the potential difference of the DC power supply 18 may be set to the potential difference V^+V8 between the deposition potential and the elution potential with reference to the potential V2 of the sliding bearing 5, and plating on the back surface 5b can be effectively prevented. . In order to confirm the effects of the present invention, a comparison is made with each embodiment. For example, as a specific implementation condition, in FIG. 5 and the counter-rotation prevention electrode 16, and when the current density of the circuit formed by the DC power source 14 is Hiroshi/dm2 (in the case of the conventional example), the back surface 5b of the sliding bearing 5 It will be plated.

(2) The DC power supply 18 is set to -0.5V, and the current density of the circuit formed by the power supply 18 is set to 0.5V. If I/dm2 (
The potential of the power source 18 is set to the reference potential OV and the elution potential B in FIG.
(set to the potential between points), plating on the back surface 5b of the slide bearing 5 can be completely prevented.

■ The DC power supply 18 is set to 100.1V, and the current density of the circuit formed by the power supply 18 is 0.
．． In the case of 1 A/dm2 (set to a potential between the reference potential OV and the deposition potential point A in FIG. 3), the back surface 5b of the sliding bearing 5 is not plated, as in the case (2).

■ When the DC power supply 18 is -4V and the current density of the circuit formed by the power supply 18 is 5A/dm2 (the third
If the elution point B in the figure is exceeded), the sliding bearing 5
Also, although the slide bearing 5 is used as the object to be plated in the above embodiment, it goes without saying that other objects can be used.
As the direct current, alternating current from an alternating current power source may be converted into direct current via a rectifier.

As described above, according to the present invention, the object to be plated is used as a cathode,
An anode is placed on the surface plating side of the object to be plated, and an electrode to prevent reverse rotation is placed on the back side of the object to be plated.
While applying a potential between the object to be plated and the anode, a potential between the deposition potential and the elution potential when the potential of the object to be plated is taken as a reference potential is applied between the object to be plated and the anti-backflow electrode,
Since it is possible to effectively prevent plating from being applied to the back side of the object to be plated, it is possible to omit the conventional work of removing the plating applied to the back side by buffing after electroplating. It will be done.

[Brief explanation of the drawing]

Fig. 1 is a connection diagram showing an embodiment of the present invention with main parts in cross section, Fig. 2 is a sectional view taken along the Rolo line in Fig. 1, and Fig. 3 is the range of voltage applied to the reverse rotation prevention electrode. FIGS. 4a to 4d are explanatory diagrams showing the relative relationship of the potentials of each part in FIG. 1 and a specific method of setting the potential difference of the DC power supply 18. 1...Plating bath, 2...Electrolyte, 3...
・・・Anode, 4... Frame, 5... Sliding bearing, 5a
...Inner surface (plated surface), 5b... Back surface, 7...
...Support stand, 8...Groove, 9...Pipe, 1
0... Permanent magnet, 14, 18... DC power supply, 16... Conductive wire (reverse rotation prevention electrode). Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. An object to be plated is used as a cathode, an anode is arranged on the side of the surface to be plated of the object to be plated, and a potential is applied between the object to be plated and the anode to electroplat the surface to be plated. In the electroplating method, a back-up prevention electrode is placed on the back side of the object to be plated, and while the potential is applied between the object to be plated and the anode, a plate is placed between the object to be plated and the back-out prevention electrode. A method for preventing plating from turning around in electroplating, which prevents plating from being applied to the back side of an object to be plated by applying a potential between a deposition potential and an elution potential when the potential of the object to be plated is taken as a reference potential. 2. Equipped with a plating tank for storing an electrolytic solution, an anode immersed in the electrolytic solution, an object to be plated as a cathode immersed in the electrolytic solution, and a power source for passing a direct current between the anode and the object to be plated. , in the electroplating device that performs electroplating with the surface to be plated of the object to be plated facing the anode, a back-turn prevention electrode is disposed on the back side of the object to be plated, and the back-turn prevention electrode is connected to the object to be plated. 1. An apparatus for preventing reverse plating in electric plating, characterized in that a power source is provided between which a direct current is applied with the side of the object to be plated as the positive side. 3. The object to be plated is a half-split sliding bearing whose inner sliding surface is the plated surface, and the sliding bearing has its back side attracted and held by a permanent magnet provided on the support stand, and the back side of the slide bearing is held by a permanent magnet installed on the support stand. 3. A plating prevention device for electroplating according to claim 2, characterized in that a prevention electrode is arranged and fixed.