Title:
METHOD AND APPARATUS FOR EXECUTING ANODIC OXIDE COATING TREATMENT TO PISTON
Document Type and Number:
Japanese Patent JPH04224695
Kind Code:
A
Abstract:
PURPOSE:To easily form hardened anodic oxide coating layer only on the top part of a piston in a short time by dipping only the necessary top part of Al alloy-made piston into electrolytic solution and sending electric current while using the piston as an anode. CONSTITUTION:Only the necessary part at the top part of Al alloy-made piston 4 is dipped into the electrolytic solution in the electrolytic vessel 10 and this is used as the anode and the electric current is sent between the anode and a cathode 7, and the tip part of piston is subjected to anodic oxidation to form the hardened anodic oxide coating layer. Ac current from an AC power source 15 is rectified into pulse DC with a rectifier 16 to make flat DC with a smoothing circuit 19 and this is supplied to the piston 4 as the anode and the cathode 7. The current is controlled so that the current density becomes constant until voltage in the electrolytic solution reaches the fixed limit value, and when the voltage in the electrolytic solution reaches the fixed limited value, while holding the voltage to this value, the current is reduced. The hardened anodic oxide coating layer is formed only on the necessary tip part of piston at high velocity without needing any masking, etc.
Inventors:
YAMAGUCHI HIROSHI
Application Number:
JP40651790A
Publication Date:
August 13, 1992
Filing Date:
December 26, 1990
Export Citation:
Assignee:
IZUMI KOGYO CO LTD
International Classes:
C25D11/04; C25D17/06; C25D17/08; (IPC1-7): C25D11/04; C25D17/06; C25D17/08
Attorney, Agent or Firm:
Shotaro Mogami
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