JPH0311230Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a device for plating the outer circumferential surface of a piston in a reciprocating engine, particularly the skirt portion.

Conventional Technology For example, pistons in vehicle engines are exposed to high temperatures and pressures and must withstand high-speed reciprocating motion, so they are now made of aluminum alloy in order to be lightweight and have good thermal conductivity. It's coming. However, if the cylinder block is also made of aluminum alloy to reduce weight, seizure is likely to occur at the contact surface between the piston and cylinder. Therefore, the parts that cause friction with the inner surface of the cylinder, that is, the skirt part, are plated with an iron-based alloy to improve wear resistance and seizure resistance.

Conventionally, electroplating has been generally used as the plating method, but in order to prevent deterioration of properties such as dimensional accuracy, weight, and thermal conductivity, various measures have been taken to apply plating only to the skirt portion as much as possible. is being done. For example, the American magazine “Plaiting”
August, 1974, pages 741-746 describes rack 1 shown in FIG. That is, in the rack 1 shown here, a pair of shielding plates 3 made of an insulating material such as synthetic resin are attached to a conductive contact bar 2 in parallel with each other, and the inner surface (opposing surface) of the shielding plates 3 is attached to a conductive contact bar 2. is provided with an engagement plate 6 that is inserted into the ring groove 5 of the piston 4 to hold the piston 4, and an opening 8 having substantially the same shape as the skirt portion 7 of the piston 4 is formed below the engagement plate 6. Furthermore, the contact bar 2 includes an engaging plate 6.
A pin 9 is formed which fits into the piston boss of the piston 4 held by the piston 4 and is electrically connected to the piston 4. In the rack 1 shown in FIG. 4, the contact bar 2 is electrically connected to the cathode, and the shielding plate 3
Plating is performed by arranging a flat anode (not shown) parallel to the plate and applying electricity in the plating solution.
In that case, since only the skirt portion 7 faces the anode plate through the opening 8, only the skirt portion 7 is plated.

Problems to be Solved by the Invention However, according to the above-mentioned Rack 1, a large number of pistons 4 can be plated at the same time, or a chemical conversion treatment etc. can be performed as a pre-plating process, but the plating is Although the skirt portion 7 to be treated has an arcuate surface, the anode is flat like the shielding plate 3, so the distance between the surface of the skirt portion 7 and the anode is not constant, and the distance is around 10 μm. There was a problem that variations occurred in the plating film thickness, which caused dimensional errors in the piston 4 itself. Furthermore, in Rack 1, the entire piston 4 held is immersed in the plating liquid or chemical conversion treatment liquid, but in that case, the plating liquid or chemical conversion treatment liquid may enter into the ring groove 5. , both etching and plating are applied to the ring groove 5, and as a result,
There was a problem that the surface roughness of the ring groove 5 deteriorated and required machining after plating.

In view of the above-mentioned circumstances, the object of this invention is to provide an electroplating device that can plate only the skirt portion of a piston with a uniform thickness.

Means for Solving the Problems In order to achieve the above object, this invention has a chuck member that grips and suspends the piston by covering the ring groove in which the piston ring is fitted from the outer circumferential side, and a chuck member that grips and suspends the piston from the outer circumferential side, and The present invention is characterized by having an anode plate in the shape of an arcuate plate having substantially the same shape as the skirt portion on the outer peripheral surface of the anode plate.

Function: In the device of this invention, plating is performed by connecting the piston to the cathode in the same manner as in the past, but in this case, the anode plate has almost the same shape as the skirt portion to be plated, and moreover, Since they face each other with a constant spacing, the current across the entire skirt portion is constant, resulting in plating with a uniform thickness.
Furthermore, since the ring groove is covered by the chuck member, it is not plated and its surface roughness does not deteriorate.

Embodiments Hereinafter, embodiments of this invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing an embodiment of this invention, and the device shown here is a system in which a chuck member 10 for holding a piston 4 in a suspended state and an anode plate 11 are integrally assembled and suspended. piston 4
It is configured to rotate. That is, the chatter member 10 has a split-collect type structure, in which two to four gripping claws 13 divided by a slit 12 are connected and integrated at the base end, and the gripping claws 13 are held together by elasticity. Each gripping claw 13 is configured to open, and furthermore, a protrusion 14 is formed on the inner circumferential surface of the tip end of each gripping claw 13 to fit into the ring groove 5 of the piston 4. This chuck member 10 has an outer cylinder 15
It is attached to the lower end of a rotary shaft 17 provided inside via a bearing 16 with an insulating plate 18 in between, and a flange 19 is provided at the lower end of the outer cylinder 15. An anode brush 20 and a cathode brush 21, which are different from each other in the radial direction, are mounted facing downward. Further, on the outer periphery of the intermediate portion of the chuck member 10, an energizing holding plate 22 made of an insulating material is arranged so as to face the flange 19, and the anode brush 20 is mounted on the outer periphery of the upper surface of the energizing holding plate 22. An anode conductive plate 24 is provided to be pressed into contact with the anode conductive plate 24, and a cathode conductive plate 25 is provided on the inner circumferential side thereof to be pressed into contact with the cathode brush 21. Further, the chuck member 10 is made of a conductive material, and one of its gripping claws 13 is fixed to the current-carrying holding plate 22 and electrically connected to the cathode conductive plate 25. . On the other hand, a pair of anode plates 11 electrically connected to the anode conductive plate 24 are provided on the lower surface of the current-carrying holding plate 22.
is installed. The anode plate 11 has an arcuate shape so as to face the skirt portion 7 of the piston 4 held by the chuck member 10 at a constant interval, and is formed in substantially the same shape as the skirt portion 7 as shown in FIG. ing.

On the other hand, to explain the configuration for opening and closing the chuck member 10, a wedge member 26 is vertically movable between the outer peripheral surface of the gripping claw 13 in a free state among the gripping claws 13, the flange 19, and the energizing holding plate 22. The chuck member 10 is configured to be closed by lowering the wedge member 26.

To explain the operation of the device configured as described above, first, in order to grip the piston 4,
The chuck member 10 is opened by moving the wedge member 26 upward as schematically shown in FIG. The chuck member 10 is closed by pushing down the wedge member 26. As a result, the protrusions 14 provided on the inner peripheral surface of the lower end of each gripping claw 13 enter and engage with the ring groove 5 of the piston 4, and
The gripping claw 13 covers the entire ring groove 5. The piston 4 held by the chuck member 10 in this way is
It is located in the middle of the pair of anode plates 11, and the skirt portion 7 faces the anode plates 11 at a constant interval. Therefore, if the upper end of the skirt portion 7, that is, the lower end of the ring groove 5, is immersed in the plating liquid 27, and the piston 4 and the anode plate 11 are energized,
Plating is applied to the skirt portion 7 of the piston 4.
In this case, since the anode plate 11 is arc-shaped and spaced apart from the skirt portion 7 at regular intervals, the thickness of the plating film formed on the skirt portion 7 can be made uniform; The plate 11 has the same shape as the skirt part 7, and the ring groove 5 has the gripping claw 1.
3, it is possible to give the skirt portion 7 a glare. Further, when plating is performed using the above-mentioned apparatus, the piston 4 and the anode plate 11 are rotated together with the chuck member 10 and the energizing holding plate 22 via the rotating shaft 17. In this way, the diffusion layer at the interface between the piston 4 and the anode plate 11 can be made small and a high current density can be maintained, thereby increasing the speed of plating.

Effects of the invention As is clear from the above explanation, according to the device of this invention, instead of using a shielding plate, the anode plate is made to have almost the same shape as the skirt of the piston, and the anode is placed at a constant distance from the skirt. Since the plate is formed into an arc shape, it is possible to almost eliminate variations in the plating thickness of the skirt portion and improve dimensional accuracy. Further, since the ring groove of the piston is covered by the chuck member, the surface roughness of the ring groove does not deteriorate, and the conventional machining of the ring groove after tightening can be eliminated.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of this invention, Fig. 2 is a view showing the shape of the anode plate and is a view taken along the - line in Fig. 1, and Fig. 3 is a diagram showing the chuck member opened. FIG. 4 is a perspective view showing a conventional plating rack. 4...Piston, 5...Ring groove, 7...Skirt portion, 10...Chuck member, 11...Anode Board.

Claims (1)

[Scope of utility model registration request] A chuck member that covers the ring groove in which the piston ring is fitted from the outer circumferential side to grip and suspend the piston, and a chuck member that faces the skirt portion at a constant interval on the outer circumferential surface below the ring groove and is approximately the same as the skirt portion. An electroplating device for a piston, characterized in that it has an anode plate in the form of an arc plate having the same shape.