SU775195A1 - Method of stabilizing alternating polarity current galvanic process - Google Patents

Description

The invention relates to electroplating and can be used in the process of chromium plating with alternating polarity. A known method of stabilizing the galvanic process at a current of alternating polarity involves adjusting the magnitude of the bath current and correcting the amount of electricity flowing through the bath during periods of anodic polarity is inversely proportional to the voltage deviation on the electrodes from the set value during cathodic polarity 1 The disadvantage of the known method is in the instability of the performance of the process of galvanic processing of products. The aim of the invention is to stabilize the performance of the galvanic processing process in a continuous technological process of manufacturing products. The goal is achieved by adjusting the current of the bath to correct the amount of electricity flowing through the bath during periods of anodic polarity is inversely proportional to the voltage deviation of the electrodes from a predetermined value during the cathode polarity, and adjusting the amount of electricity to the bath depending on directly proportional to the change in current output. The method is carried out as follows. When the chrome plating bath is operating, the electrolyte is gradually depleted in chromic anhydride, and the current efficiency and electrical conductivity of the electrolyte decrease. The degradation of conductivity with stable values of current and temperature leads to an increase in the voltage on the electrodes of the bath, which is an indirect parameter for estimating the magnitude of the current output. To compensate for the reduction in coating thickness due to a decrease in current efficiency, it is necessary to reduce the amount of electricity flowing through the bath during anodic polarity without changing its duration by reducing the anodic current. At the same time, the duration of the electroplating process, which is the sum of the cathodic and anodic polarities, remains constant.

the rhythmic release of parts and the incorporation of galvanic processing into a continuous technological process of manufacturing products is provided.

The method is carried out using a device whose block diagram is shown in the drawing.

The electroplating bath 1 is powered by a reverse thyristor rectifier 2 having an automatic current control system, for example, consisting of current transformers 3 and a regulator 4 controlling the ignition circuit of the thyristor rectifier 2. The anode current correction circuit consists of a memory v. 5 with a current sensor 6, which changes the gain of amplifier 5, and element 7, which detects a change in voltage on the electrodes of the bath 1. In the 7-hour element, the voltages from the electrodes of bath 1, removed by potentiometer 8, to a comparison resistor 9 via a separation diode 10. This voltage is compared to a stable voltage on a silicon Zener diode 11. The voltage taken from a resistor 9 is fed to a storage amplifier 5. The signal from an amplifier 5 is fed to a regulator 4 to correct the anode current value .

Example. Piston rings are chrome plated on a variable polarity current in an electrolyte of the following composition, g / l:

SgOg. 260

H SQj2.3-2.6

Ct-OQ, Not more than 10

FeNe more than 5

with a current output of 15%, with a duration of repetitive cathode polarity of 20 min, duration of repetition to an anodic polarity of 40 s; the total coating thickness is 0.16 + 0.01 mm, the cathode polarity current is 800 A, the anodic polarity is 400 A. After treatment of 600 piston rings, the electrolyte composition changes as a result of a decrease in the concentration of chromic anhydride () from 260 to 210 g / l, and the current efficiency is also reduced from 15% to 12%. The consequence of this is an increase in voltage on the electrodes of the bath during cathodic polarity from 5 to 6 V. To obtain a given coating thickness (0.15 mm) and maintain an anodic polarity time of 40 s with further chromium plating in this electrolyte the current is reduced to 320 A. A change in voltage at the electrodes of the bath by 1 V during cathode polarity is detected by element 7 and fed to a memory amplifier 5, which. changes the setting of the anode current of the regulator 4 and reduces the current to 320 A. The correction of the value of the current of the anode polarity occurs continuously. In this case, the duration of both cathodic and anodic polarities, and therefore the total time of the process, is not. vary.

The proposed method allows to stabilize the process in time

0 to create an automated electroplating area, carrying out the rhythmic production of parts, and embed galvanic processing in a continuous process

5 manufacturing products.

Claims (1)

Invention Formula A method of stabilizing a galvanic process on a variable polarity current, including regulating the magnitude of the bath current and correcting the amount of electricity flowing through the bath during periods of anodic polarity is inversely proportional to the voltage deviation on the electrodes from the predetermined value during cathodic polarity, characterized in , in order to stabilize the performance of the process of galvanic processing in a continuous technological process of manufacturing products, the correction of the amount of electricity is exhibit a change in the magnitude of the anode current depending bath, directly proportional to the current efficiency change. Sources of information taken into account in the examination 1. Author's certificate of the USSR 0 per application 2567383, C 25 D 21/12, 1978. X