Method for producing chromium plated parts, and chromium plating apparatus
AssigneeHitachi Automotive Systems, Ltd.
InventorsYuichi KOBAYASHI, Kiyokazu NAKANE
Life of this patent
Estimating the term…
Abstract
According to the method for producing chromium plated parts, a plurality of workpieces are immersed in a chromium plating bath, a plating treatment is performed by using a pulse current, and chromium plating layers that have compressive residual stress and suppressed cracking are deposited on surfaces of the plurality of workpieces. A direct current from plating separation lower limit current density up to a range in which the chromium plating layers have compressive residual stress is superimposed during downtime of application of the pulse current.
Claims11
A method for producing chromium plated parts comprising the steps of:
- immersing a plurality of workpieces in a chromium plating bath;
- performing a plating treatment by application of a pulse current;
- and
- depositing chromium plating layers, which have a compressive residual stress, on surfaces of the plurality of workpieces,
- wherein a direct current from a plating separation lower limit current density up to a range in which the chromium plating layers have the compressive residual stress is applied only during a downtime of the application of the pulse current, the direct current (DC) being greater than zero ampere, and
- wherein the plating separation lower limit current density is in a range from 10 to 35 A/dm2,
- wherein the pulse current is caused to pass through a high-pass filter that allows only a pulse waveform to pass therethrough and the direct current is caused to pass through a low-pass filter that allows only a DC waveform to pass therethrough, and both the pulse current and the direct current are then synthesized,
- wherein a pulse waveform shape that prevents a reverse flow of mutual electric currents is adjusted by a pulsed power supply device, and
- wherein the direct current is adjusted by a DC power supply device to be applied during the downtime of the application of the pulse current.
A chromium plating apparatus comprising:
- a treatment tank that accommodates a chromium plating bath;
- cathode electrodes that energize workpieces made of a metal while the workpieces are suspended in the treatment tank;
- anode electrodes that are arranged in the vicinity of the workpieces that are suspended in the treatment tank;
- and
- a pulsed power supply that is connected to the cathode electrodes and the anode electrodes and applies a pulse current thereto,
- wherein the pulsed power supply superimposes a direct current from a plating separation lower limit current density up to a range in which compressive residual stress is obtained during downtime of the pulse current.
Dependencies are inferred from the claim text.