122results about "Power source circuits" patented technology

A smooth layer of a metal is electroplated onto a microrough electrically conducting substrate by immersing the substrate and a counterelectrode in an electroplating bath of the metal to be electroplated and passing a modulated reversing electric current between the electrodes. The current contains pulses that are cathodic with respect to said substrate and pulses that are anodic with respect to said substrate. The cathodic pulses have a duty cycle less than about 50% and said anodic pulses have a duty cycle greater than about 50%, the charge transfer ratio of the cathodic pulses to the anodic pulses is greater than one, and the frequency of said pulses ranges from about 10 Hertz to about 12000 Hertz. The plating bath is substantially devoid of levelers and may be devoid of brighteners.

A smooth layer of a metal is electroplated onto a microrough electrically conducting substrate by immersing the substrate and a counterelectrode in an electroplating bath of the metal to be electroplated and passing a modulated reversing electric current between the electrodes. The current contains pulses that are cathodic with respect to said substrate and pulses that are anodic with respect to said substrate. The cathodic pulses have a duty cycle less than about 50% and said anodic pulses have a duty cycle greater than about 50%, the charge transfer ratio of the cathodic pulses to the anodic pulses is greater than one, and the frequency of said pulses ranges from about 10 Hertz to about 5000 Hertz.

In order to shorten a process chain for chip removing processing of a crank shaft after coarse machining and after hardening according to the invention a combination of turn milling or single point milling is proposed as a first step and a subsequent line machining step through finishing or electro chemical etching is proposed.

The invention relates to the metalworking field, particularly to electrochemical sizing machining, and can be used for manufacturing of machine workpieces having an intricate profile and shaping furniture from chromium-containing steels and alloys operating in aggressive environment under excessive friction.

Technical effect: improving machining accuracy by forming a lustrous layer on the machined surface and reduction of concentration of hexavalent toxic chromium ions in a waste electrolyte solution.

Summary of invention: in the initial step, the unipolar electrochemical machining by operating pulses of normal polarity is carried out forming a layer enriched with chromium ions in the electrolyte area adjacent to the workpiece surface, then, upon achievement of the predetermined machining depth, shape and size of the workpiece, the operational current pulses of normal polarity and the machining electrode feeding are turned off and the residual polarization voltage value at the interelectrode gap is measured using the test high-frequency pulses of normal polarity, then low voltage pulses of opposite polarity synchronized with the phase of maximal approximation of the electrodes to each other are turned on and chromium cathode deposition onto the machined workpiece surface is carried out by means of alternating the pulses of opposite polarity with test high-frequency pulses of normal polarity and controlling the chromium deposition by increment of residual polarization value relative to its value after operational pulses of normal polarity.

The invention relates to a method for the production of aero-dynamic structures during the production of integrally bladed gas turbine rotors. Aerodynamic structures of an integrally bladed gas turbine rotor are produced on a rotor disk base body, whereon the end contours are precise, by removing material according to an electrochemical removal process, i.e. by means of an electrochemical machining (ECM)-process. The method comprises the following steps: a) preparing a rotor disk base body which is made of a material which is difficult to machine; b) removing the material which is between the blade wings until a specific dimension is obtained, according to a removal process; c) preparing at least one working electrode in order to finish at least one aerodynamic structure of an integrally bladed gas turbine rotor. The contours of the or each of the working electrodes are adapted to the contours of the aerodynamic structure, which are produced by means of the respective working electrode, such that a gap between the rotor disk base body and a working electrode are produced in an approximately identical manner during the removal process of the material; d) electrochemically machining the or each aerodynamic structure in an electrochemical sinking by placing the rotor disk base body and the or each working electrode in an electrolyte and by applying voltage and/or current, whereby the applied current and/or voltage is temporally pulsed; e) pressure-rinsing the gap which is filled with electrolytes between the aero-dynamic structure and the or each working electrode by a pulsed movement of the or each working electrode.

A switching element (SW1) opens and closes in the frequencies of MHz-order. A reactor (L1) resonates with the stray capacitance between the electrodes and supplies the resulting resonant current to between the electrodes. The resonant current does not flow through a DC power supply (V1). A series resonance between a capacitor (C1) and a stray inductance (Lx) allows the resonant current to be ideally supplied from the rector (L1) to between the electrodes without receiving the influence of the stray inductance (Lx). A high-frequency voltage asymmetrical in the positive and negative directions is applied between the electrodes and a current pulse can be shortened, so that finish machining with a high degree of surface roughness can be performed.

A method for on-line removal of cathode depositions during electrochemical process. The process control unit (30) is arranged to alternate the unipolar machining voltage pulses U1 with the voltage pulses of opposite polarity U2 to the work piece (2) and the cathode (3). The process control unit comprises an arrangement to determine the amount of cathode depositions on-line based on the operational parameter. Only in case the operational parameter exceeds the allowable level, the process control unit (30) alternates the unipolar machining voltage pulses U1 with the voltage pulses of opposite polarity U2. In this case the cathode wear is minimized.

In order to shorten a process chain for material removing machining of a crank shaft after rough machining and after hardening a combination of circumferential turn milling as a first step and subsequent dry grinding as a second step is proposed according to the invention.

The present invention is capable of improving machining accuracy and machining efficiency by providing a regular rest time during a cycle in which machining is considered to become unstable during machining performed by the self-oscillation of a capacitor discharge in which the inter-electrode capacitance of a capacitor is used. This electrical discharge machining apparatus is provided with: a power source; an inter-electrode space formed by an electrode and the workpiece; a current-limiting resistor connected between the power source and the inter-electrode space; a switching element for turning on and off the application of voltage from the power source to the inter-electrode space; an inductance element connected serially between the switching element and the inter-electrode space; and a control unit for controlling the switching element, the control unit causing the switching element to turn on and off according to a switching pattern having an on-pulse duration (ΔT on) such that during the on-pulse time the voltage of the inter-electrode space can reach the voltage of the power source, and a rest duration (ΔT off) that ranges from the duration (ΔT ic) of the discharge current flowing during discharge of the capacitor, to less than the self-oscillation cycle (ΔT so).