JP2791740B2 - Composite plating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for applying, for example, nickel plating to the inner peripheral surface of a hollow member such as an engine cylinder.

[0002]

2. Description of the Related Art For example, since a piston slides inside an engine cylinder, it is necessary to improve the wear resistance of the inner peripheral surface of the cylinder particularly when the cylinder block is made of an aluminum alloy. By the way, when an opening must be provided on the inner peripheral surface of a cylinder as in a crank scavenging two-stroke engine, it is difficult to fit a sleeve into the cylinder. Composite plating may be applied to the peripheral surface. In order to apply composite plating to the inner peripheral surface of such a cylinder, electrodes are inserted with a gap between the inner peripheral surface of the cylinder and silicon carbide fine particles mixed in nickel sulfate in the gap. There is known a method in which a so-called nicazil plating in which fine particles of silicon carbide are contained in nickel by flowing a composite plating solution is performed. However, the flow rate of the composite plating solution cannot be made too high in order to include the fine particles in the composite plating layer, so that the flow of the composite plating solution in the gap becomes laminar. Then, on the upstream side of the composite plating solution, fine particles such as silicon carbide are well contained in the composite plating layer. The inclusion amount of fine particles of
There is a problem that the composite plating layer becomes uneven between the upstream side and the downstream side.

In order to solve such a problem,
For example, Japanese Patent Application Laid-Open No. 52-93636 discloses a technique in which the flow direction of a composite plating solution is reversed at regular intervals.

[0004]

In the above-described conventional method in which the flow direction of the composite plating solution is reversed at regular intervals, the state of the composite plating at both end portions of the cylinder can be made the same, but the center portion is formed at both ends. There is a disadvantage that the composite plating is less likely to occur than the portion, and the tendency increases as the length of the cylindrical portion increases.

In view of the above problems, an object of the present invention is to provide a composite plating apparatus capable of uniformly performing composite plating on the inner peripheral surface of a hollow member.

[0006]

According to a first aspect of the present invention, there is provided an apparatus for performing composite plating on an inner peripheral surface of a hollow member. An electrode inserted with a predetermined gap between the electrode and the inner peripheral surface, and an ejection port facing below the electrode in the inserted state, and an inner diameter of the ejection port. Is provided with a composite plating solution supply pipe having the same diameter as or smaller than the outer diameter of the electrode, and supplying the composite plating solution containing bubbles to the gap from the discharge port. .

According to a second aspect of the present invention, in the first aspect of the present invention, the distal end of the electrode is formed to have a gradually decreasing diameter toward the distal end.

[0008]

When bubbles are mixed in the composite plating solution, the bubbles rise and the composite plating solution is agitated, and the flow of the composite plating solution in the gap becomes turbulent, and the downstream portion of the inner peripheral surface also flows. A composite plating solution containing fine particles is supplied to make the composite plating layer uniform. Further, when the inner diameter of the discharge port is equal to or smaller than the outer diameter of the electrode, all the bubbles contained in the composite plating discharged from the discharge port to the hollow portion once strike the tip of the electrode. Then, the bubbles adhere to the surface of the electrode, and rise in the gap while remaining attached to the surface of the electrode. Since the bubbles rise while pushing away the composite plating solution located above the bubbles, the rising of the bubbles pushes the composite plating solution containing a large amount of fine particles near the electrode surface toward the inner peripheral surface side of the hollow member, thereby causing the inner peripheral surface to move. The composite plating solution containing a large amount of fine particles is supplied over the entire area of the surface, so that the inclusion amount of the fine particles in the composite plating layer becomes more uniform.

[0009] When the moving direction of the bubble suddenly changes when the bubble colliding with and adheres to the tip of the electrode rises along the surface of the electrode, the bubble may be separated from the surface of the electrode. Thus, as described above, the tip of the electrode is gradually reduced in diameter toward the tip, so that the moving direction of the bubbles does not suddenly change, and the separation of the bubbles is prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG.
It is a cylinder block of a stroke engine, and is provided with a cylinder Wc that penetrates vertically, and a space S for air supply and scavenging is provided in the cylinder Wc so as to be opened. And sealed. The cylinder block W is mounted on the holding table 1 and is set such that the composite plating solution supply pipe 11 provided on the holding table 1 and the cylinder Wc coincide. An electrode 2 having a substantially hemispherical tip is inserted into the cylinder Wc from above, and a gap G is formed between the electrode 2 and the inner peripheral surface Wf of the cylinder Wc. The composite plating solution supplied from the solution supply pipe 11 is set so as to flow through the gap G. Here, assuming that the diameter of the electrode 2 is D, and the inside diameter of the discharge port 11a of the composite plating solution supply pipe 11 that faces the tip of the electrode 2 is d, in the case of this embodiment, D
> D.

Incidentally, the composite plating solution supply pipe 11 is connected to a pump for supplying a composite plating solution (not shown) through a pipe 12, and an air mixing path 1 is provided in the middle of the pipe 12.
3 are connected. A compressor (not shown) is connected to the air mixing path 13 so that a predetermined amount of air is mixed into the composite plating solution in the pipe 12. The air mixed in this way forms bubbles 14 and moves up the composite plating solution supply pipe 11 together with the composite plating solution, and
a is discharged into the cylinder Wc. Then, the gas flows through the gap G, flows out into the space 31 of the pressing member 3 pressing the upper surface of the cylinder block W, and is returned to the tank (not shown) via the pipe 32. Then, after being evacuated in the tank, it is again sent out to the pipeline 12 by the pump.

According to the above configuration, as shown in FIG.
Since> d is set, all the bubbles 14 in the composite plating solution discharged from the discharge port 11a collide with the tip of the electrode 2 and adhere to the surface of the electrode 2. Since the tip of the electrode 2 is formed in a substantially hemispherical shape, the bubbles 14 attached to the surface of the electrode 2 rise while adhering to the surface without peeling. At this time,
The composite plating solution sufficiently containing fine particles, which is located at the upper part P of the bubble 14 attached to the surface of the electrode 2, is pushed away toward the inner peripheral surface Wf by the rise of the bubble. Since the bubbles 14 rise along the surface of the electrode 2 to a portion corresponding to the upper end of the cylinder Wc, the composite plating solution containing a large amount of fine particles from the electrode 2 side toward the inner peripheral surface Wf over the entire inner peripheral surface Wf. Is supplied to obtain a uniform composite plating layer.

In this embodiment, 400 g of nickel sulfate, 35 g of boric acid, and 60 g of fine powder of silicon carbide are added per liter of water as a composite plating solution.
Further, 2.5 g of saccharin sodium was added to adjust the hardness to pH = 4, and nickel-containing nickel fine particles containing silicon carbide particles were subjected to composite plating, that is, so-called nicazil plating was applied. The composite plating conditions are as follows: the flow rate of the composite plating solution in the gap G when air is not mixed is 15 cm / s, the temperature of the composite plating solution is 60 ° C., and the cathode current density is 28 A / dm ² . Further, although the inner diameter d of the discharge port 11a is smaller than the diameter D of the electrode 2, both may be set to the same size. Even in such a case, all the bubbles 14 may adhere to the surface of the electrode 2. it can.

In the above embodiment, air is simply mixed. However, when the size of bubbles is reduced, air is mixed through a porous material, or the composite plating solution is mixed upstream of the discharge port. What is necessary is just to agitate and to fragment air bubbles. Further, in the above embodiment, the tip of the electrode 2 is formed in a substantially hemispherical shape. However, the electrode 2 may have a tapered shape or another shape as long as it gradually becomes thinner toward the tip. Furthermore, although air was mixed into the composite plating solution, helium gas, argon gas, nitrogen gas, and other inert gases may be mixed.

[0015]

As is apparent from the above description, according to the present invention, the bubbles mixed in the composite plating solution are raised along the electrode, and the composite plating solution containing a large amount of fine particles near the electrode surface is removed. Since supply is performed over the entire peripheral surface, uniform composite plating can be applied to the inner peripheral surface.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an apparatus for carrying out the present invention.

FIG. 2 is a partially enlarged view showing details of bubbles attached to an electrode surface.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Holder 2 Electrode 3 Holding member 11a Discharge port 13 Air mixing path 14 Bubble D Electrode diameter d Internal diameter of discharge port G Gap Wc Cylinder Wf Inner peripheral surface

Continuation of the front page (56) References JP-A-52-39535 (JP, A) JP-A-55-54598 (JP, A) JP-A-52-93636 (JP, A) JP-A-7-118894 (JP) , A) Actual opening 52-111720 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) C25D 7/00-7/12 C25D 15/02

Claims (2)

(57) [Claims] 1. An apparatus for performing composite plating on an inner peripheral surface of a hollow member, wherein the hollow member is held at a predetermined distance from the inner peripheral surface in a state where the generatrix of the inner peripheral surface is oriented vertically. A composite plating solution having an electrode inserted with a gap therebetween and a discharge port facing below the electrode in the inserted state, wherein the inner diameter of the discharge port is equal to or smaller than the outer diameter of the electrode; A composite plating apparatus comprising: a tube; and supplying a composite plating solution containing air bubbles from the discharge port to the gap. 2. The composite plating apparatus according to claim 1, wherein a tip portion of the electrode is formed to have a gradually decreasing diameter toward the tip.