RU2647413C2 - Method of electrochemical processing with unshaped electrode tool and devices for its implementation - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to the field of electrochemical processing and can be used to cut narrow curved grooves and slots in parts made of high-strength steels and alloys. In the method, the electrochemical processing is carried out by multi-coordinate movement in several successive transitions by a rotating electrode tool, made in the form of a fixed at both ends long elastic plate of permanent cross-section with a substantially different ratio of overall dimensions in the direction of the symmetry axes rotating around the longitudinal axis. At that, in the method the first transition can be carried out at a constant voltage, at that, the axes of the plate initial and final cognominal cross-sections are turned relative to each other about the longitudinal axis, by a certain angle of shear γ, providing the creation of a screw twisting of the electrode tool. first transition can also be performed on a pulsed voltage, without the plate first twisting at a shear angle of γ=0. At that, voltage pulse or a group of voltage pulses switching phase in each turn of the electrode tool is varied depending on the direction of the supply vector, ensuring the switching of a pulse or a group of pulses at a time, when the axis of symmetry parallel to the long side of the cross section of the electrode tool with the supply vector forms a predetermined angle of ϕ, less than 90 degrees, and switching off the voltage after turning the electrode tool by an angle of 2ϕ from the moment of switching on. At that, further transitions are carried out in the groove previously obtained at the first transition, at that, the voltage pulses are supplied synchronously with the rotation of the electrode tool, but with a pulse switching on phase shift and the pulse switching off phase by 90 degrees relative to the supply velocity vector in the direction of the finally processed groove surface.

EFFECT: providing a larger depth of the cut groove, the possibility of a complex contour cutting with the generatrix variable slope angles.

26 cl, 11 dwg, 1 ex

Description

The invention relates to the field of electrochemical processing (ECHO), mainly cutting narrow curved grooves and slots in parts of high strength steels and alloys with a non-profiled electrode-tool in the form of a rod fixed on one side or a plate fixed on both ends, and can be used, for example, in the manufacture of die cutting dies and drawing dies.

A known method of wire electrochemical cutting (US patent No. 4052274, MKI ² B23P 1/12, 10/04/1977), in which the billet and cathode are installed opposite each other in a bath with an electrolyte and a pulse current is passed between them. In this case, the part moves relative to the electrode-tool. A thin wire is used as the cathode, the end sections of which are fixed in the support device.

The disadvantage of this method is that it does not provide control and management of the distribution of the intensity of electrochemical dissolution along the length of the electrode tool. Unevenness in the distribution of current density can occur due to significant gradients of gas filling and electrolyte temperature. Increasing the pause between pulses and reducing the pulse duration to reduce gradients is associated with a loss of performance.

There is also known a method of electrochemical processing of a metal surface in a flowing electrolyte using a tool electrode consisting of elementary whisker electrodes moving relative to the machined surface (AS USSR No. 1035902, B23H 3/00, 05/15/1986), in which, in order to increase processing quality, reducing electrolyte consumption and improving sanitary and hygienic working conditions, the process is carried out at current densities of 2-8 A / cm ² , the speed of movement of the electrode tool 1-40 cm / min, the pressure of the pressure electrode tool m 0.05-1 kg / cm ² , the whisker electrodes of which are made of carbon fiber material with a specific electrical resistance of 0.01-0.25 Ohm⋅cm.

The disadvantage of this method is that, firstly, the high resistivity of the material of the electrode-tool will cause a significant ohmic voltage drop with a corresponding change in current density along the length of the processed surface; secondly, it is very problematic to make such an electrode with a small diameter, for example, less than 200 microns; the use of low current densities is unacceptable for a number of materials, because able to cause passivation and does not provide the required surface quality and performance.

There is also known a method of electrochemical treatment with a non-profiled electrode-tool moving along its axis (AS USSR No. 513824, B23P 1/04, 05/15/1976), in which, in order to improve the accuracy of processing, an uniform electrolyte film is created on the electrode-tool thickness, constant composition and concentration by extracting it from an aqueous electrolyte solution at a speed of 1-20 m / s.

The disadvantage of this method is that it requires constant rewinding of the electrode wire, which should have a considerable length; for implementation also requires sufficiently sophisticated mechanical devices for tensioning and rewinding the wire at high speed. It is also highly doubtful that a thin water film is capable of efficiently updating the interelectrode medium; it is very possible that with a relatively large thickness of a narrow slot to be cut, it will be destroyed mechanically or due to gas filling and heating processes.

There is also known a method of electrochemical processing with a non-profiled electrode (Japanese patent No. 54-137196, B23H 7/02, 7/04, 04/17/77, in which the non-profiled electrode tool (EI) is positioned obliquely with respect to the workpiece electrode (EZ) ) In this case, the processing of the arcuate section of the conical surface of the EZ is performed, starting from the rectilinear section of the conical surface. When implementing the method on the arcuate sections maintain a constant width of the processing groove, providing the required dimensional accuracy. For this, the width of the processing groove, the corresponding feedrate of the electrode-tool for a given height of the EM and the operating voltage are controlled so that, at the processing speed of the arcuate section for a given height of the EM, the working voltage provides the same width of the groove of the processing as in the straight section.

The disadvantage of this method is that only a change in the feed rate of the EI and a change in voltage do not guarantee the uniformity of metal removal along the entire length of the EI and the achievement of minimum lateral gaps.

There is also a method of electrochemical processing (US patent No. 4213834, MKI ³ B23P 1/14, 07/22/1980), in which the process is carried out on a pulsed current with vibration of the electrode-tool. In this case, the supply of current pulses is carried out mainly in the phase of the closest approximation of the electrodes, and the supply of EI is regulated by comparing with the absolute value of the second derivative of the electric resistance of the MEP.

The disadvantage of this method is that it does not consider such important processing parameters as a non-profiled cylindrical EI, such as the EI rotation frequency. It does not allow to control and manage cavitation processes and changes in gas filling of the electrolyte along the length of EI. Does not contain functionality to reduce the width of the slotted groove.

The closest in technical essence and the achieved result to the claimed method is a method of electrochemical treatment with a rotating rod non-profiled electrode-tool, along the outer surface of which a continuous flow of electrolyte moves (as USSR AS No. 327752, MKI ² B23P 1/04, 07/05/1976 g .), in which, with the aim of increasing productivity and processing accuracy, the electrolyte flow is forcibly formed using a nozzle nozzle into a high-speed jet, coaxial to the electrode. According to this method, the velocity of the electrolyte stream is selected depending on the thickness of the workpiece, but not less than 5 m / s, also to control the technological parameters and change the cutting width, the diameter of the stream, the speed of the electrode and the voltage across the electrode gap are changed.

The disadvantage of this method is that achieving a continuous stream of electrolyte around the electrode-tool over a length of more than 20 mm is very problematic, and secondly, temperature gradients and gas filling of the electrolyte will inevitably arise along the length of the stream, which reduce the processing performance in general. In the prototype method, the issue of reducing the taper or the angle of inclination of the walls of the slot to be cut at the inlet and outlet of the electrode-tool from the interelectrode gap is also not resolved.

Thus, the known methods of electrochemical processing cannot provide stable and high-performance electrochemical cutting of narrow grooves and crevices in parts of large thickness. Since they do not provide actions for the effective evacuation of products of electrochemical reactions and the alignment of the physicochemical properties of the interelectrode medium in the entire volume of the interelectrode space.

A known machine for electrochemical processing with a non-profiled electrode-tool (Japanese patent No. 54-146100, B23H 7/02, 05/08/77), which contains an electrode-tool, forming an electrode gap (MEP) with the electrode-blank. MEP is filled with a working fluid and an electric current is passed through it, cutting EZ. EI and EZ move relative to each other, while the EZ is processed along a given contour. According to this invention, the machine contains two reservoirs with working fluids having a relatively high and relatively low resistivity, as well as a third reservoir with a mixture of these fluids, so as to obtain a fluid with the desired resistivity. The machine contains pumps connected to the respective tanks, and a valve that is connected to the third tank and the exhaust pump. The valve changes the direction of fluid flow. There is also a program-controlled regulator that controls the pumps, the valve and changes the position of the EZ.

The disadvantage of this machine is that, firstly, the problem of efficiently updating the interelectrode medium when cutting narrow and deep grooves is not solved; secondly, the high cost and complexity of the design; thirdly, a significantly different rate of updating the interelectrode medium at the inlet, in the middle and at the outlet of the electrolyte from the slot to be cut. The latter affects the intensity of the anodic dissolution and the shape of the groove.

Also known is a machine for electrochemical cutting with a cylindrical electrode, containing mechanisms for moving the product and (or) tool located on the bed, a chamber with a working head-bracket and electrode and a system for supplying electrolyte to the working area (AS USSR No. 342748, MKI ² B23P 1 / 04, 05.07.76), in which, in order to ensure the accuracy of processing by forming a tightly closed electrolyte jet, the working head is equipped with a conoidal nozzle, inside of which, along its axis, an electrode-tool is placed. To ensure coaxiality of the electrolyte stream and the electrode, it is equipped with a mutual alignment system of the guide nozzle and the electrode, made in the form of movable upper and lower electrode supports, bearing mounted cones and adjustment mechanisms. In this case, the adjustment mechanism is made in the form of spring-loaded levers with slots constantly pressed to the set screws through which an electrode is passed.

The disadvantage of this machine is that the electrolyte stream formed in the working head retains its continuity over a relatively short length, which does not allow for efficient evacuation of products of electrochemical reactions with a groove thickness of more than 20 mm and does not allow to cut narrow (less than 0.5 mm) grooves.

Known tool head for electrochemical treatment with a non-profiled electrode-tool, containing two brackets and a nozzle for forming an electrolyte jet (AS USSR No. 621521, MKI ² B23P 1/04, 08/30/78), in which, in order to exclude ripples and spatter the electrolyte stream, the nozzle exit end face is made in the form of a diverging cone, and a chamber with holes for the inlet and outlet of the electrolyte is placed on the lower bracket, the inlet opening being 1.2-2.0 of the jet diameter, and the outlet hole located on the side wall of the chamber stie, providing her the incomplete filling of electrolyte.

The disadvantage of this device is that the nozzle forming the electrolyte stream does not allow for the efficient evacuation of products of electrochemical reactions along the entire length of the tool electrode, especially when cutting narrow and deep grooves.

Known electrochemical machine for shaped cutting with an electrode wire or rod, containing an electrolyte supply system, a direct current source, mechanisms for longitudinal and transverse movement of the table with the workpiece located on the bed, a working head mounted inside the working chamber in the form of a bracket with two mutually centered supports intended for fastening electrode tool. The upper support with a cone-shaped or conically converging nozzle forms an electrolyte stream coaxially with the electrode-tool. In the lower support, the rotation of the pinion-roller adjusts the tension of the electrode-tool. The working head, mounted on the vertical part of the bed, provides the installation of the electrode tool perpendicularly or at an angle of at least 75 ° relative to the working plane of the table (Electrochemical machine model MA4429. Electrophysical and electrochemical machines. Catalog of domestic machines. M., NIIMASH, 1969) .

This machine is the closest to the claimed and adopted by us as a prototype.

The disadvantage of this machine is that the electrolyte stream formed in the working head does not allow for efficient evacuation of sludge with a workpiece thickness of more than 20 mm. The non-sliding bracket and the absence of a mechanism for changing the angle of inclination of the longitudinal axis of the electrode-tool relative to the working plane of the table during the cutting process limits the technological capabilities of the machine. In addition, there is no possibility of continuous adjustment of the tension of the electrode-tool, eliminating the curvature of its axis under the action of forces arising in the interelectrode gap, a change in its temperature or twist angle.

A known unipolar pulse generator for electrochemical processing (RF patent No. 2203785, B23H 1/02, B23H 3/02, 05/10/2003), consisting of a single-phase transformer, the primary winding of which is connected to the mains voltage, the secondary power winding through a power thyristor is connected to the interelectrode gap, shunted by the diode in the opposite direction. In parallel to the power thyristor, an LC circuit from a series-connected capacitor and inductance is connected through a switching thyristor. In parallel with the LC circuit, a transformer recharge winding is connected through a recharge thyristor and a two equal circuit connected in opposite-series, recharge and commutation transformer windings through a shunt thyristor. Such a generator can generate one or two pulses synchronously with the frequency of the network with an inclined peak of the pulse, and the amplitude of the pulse is controlled by shifting the phase of the pulse.

The disadvantage of the analogue is limited functionality due to the lack of regulation of the duration and phase of the pulse. In addition, the generator is not able to work both in constant voltage mode and in pulse current mode with good voltage stabilization.

A known power source containing a stabilized voltage source and an electronic key ("Physicochemical processing methods in the production of gas turbine engines" edited by B.P. Savushkin, M. 2002, p. 30).

This power source is the closest to the claimed and adopted by us as a prototype.

The disadvantage of the prototype is the limited functionality due to the lack of regulation of the duration and phase of the pulse.

The task to which the invention is directed is the expansion of functionality, improving the accuracy of processing and surface quality.

The technical result is the provision of a large depth of the slotted groove, the possibility of complex contour cutting with variable angles of inclination of the generatrix.

The problem is solved, and the technical result is achieved by the method of electrochemical treatment with a rotating non-profiled electrode-tool, including the supply of electrolyte to the treatment zone through a nozzle, according to which, according to the invention, the processing is carried out by multi-axis movement in several successive transitions by the electrode-tool, made in the form fixed from both ends of a long elastic plate of constant cross section with a significantly different ratio of overall dimensions in the direction of the axes of symmetry rotating around the longitudinal axis, the first transition being carried out at constant voltage, while the axis of the initial and final cross sections of the same name of the plate are rotated relative to each other, around the longitudinal axis, by a certain angle of shift γ, ensuring the creation of a helical twist of the electrode tool, and subsequent transitions are carried out in the groove previously obtained at the first transition, while voltage pulses are supplied synchronously with the rotation of the electrode-tool, also ak and recessing groove on the pulse voltage, but with an offset phase switching pulse and the phase of the pulse by 90 degrees with respect to the feed rate of the vector in the direction toward the surface of the slot machined clean.

The problem is solved, and the technical result is also achieved by the method of electrochemical treatment with a rotating non-profiled electrode-tool, including the supply of electrolyte to the treatment zone through a nozzle, according to which, according to the invention, the processing is carried out by multi-axis movement in several successive transitions by the electrode-tool, made in the form of fixed with both ends of a long elastic plate of constant cross section with a significantly different ratio of overall p of measurements in the direction of the axis of symmetry, rotating around the longitudinal axis, the first transition is carried out at a pulse voltage, without first twisting the plate at a shear angle γ = 0, while changing the phase of the voltage pulse or group of voltage pulses in each revolution of the electrode-tool, depending on the direction supply vectors so that the inclusion of a pulse or group of pulses is carried out at the moment when the axis of symmetry parallel to the long side of the cross section of the electrode-tool forms by the feed vector, the predetermined angle ϕ is less than 90 degrees, and the voltage is turned off after turning the tool electrode by an angle of 2ϕ from the moment of switching on, and subsequent transitions are carried out in the groove previously obtained at the first transition, while voltage pulses are supplied synchronously with the rotation of the electrode tool, as well as when cutting a groove at a pulsed voltage, but with a shift of the pulse on and phase off phases by 90 degrees relative to the feedrate velocity vector towards the machined surface ited groove.

In addition, according to the invention, they can change the width of the slot to be cut by adjusting the angle of the voltage pulse ϕ, since as the angle of the voltage pulse ϕ increases, the width of the groove b increases, and when the angle of the voltage pulse ϕ decreases, the groove width b decreases.

In addition, according to the invention, in the case of reducing the width of the groove to the length of the long side of the cross section of the electrode-tool when a contact occurs between the electrode-tool and the workpiece, the supply of the electrode-tool is stopped for a period of revolution.

In addition, according to the invention, the rotation frequency and the twist angle can be changed in such a way that, with an increase in the thickness of the part, the twist and the number of revolutions are increased without exceeding the threshold for cavitation in the interelectrode space along the entire length of the tool electrode, and with a decrease in the thickness of the part, the twist is increased and reduce the rotational speed, while providing sufficient conditions for the evacuation of products of electrochemical reactions from the interelectrode space and preventing a critical increase in the lawn olneniya electrolyte or effervescence.

In addition, according to the invention, the occurrence of cavitation in the interelectrode space can be controlled by a sharp, higher than an empirically determined setting, increase in the electrical resistance of the interelectrode gap along the leading edge of the pulse.

In addition, according to the invention, a critical increase in gas filling of the electrolyte can be controlled by a sharp, higher than an empirically determined set point, increase in electrical resistance of the interelectrode gap along the trailing edge of the pulse.

In addition, according to the invention, when cutting parts with an inclined generatrix to obtain a given part size, the axis inclination of the electrode of the tool can be adjusted in accordance with the magnitude and sign of the difference in the velocities of the feed vectors of the electrode of the tool in its initial and final section, so that with a positive the magnitude of the difference in the velocities of the supply vectors, the slope of the axis of the electrode of the tool with respect to the vertical axis of the machine is increased, and if negative - reduced.

The problem is solved, and the technical result is also achieved by a machine for electrochemical processing with a non-profiled electrode-tool containing an electrolyte supply system, a power source, a bed with a mechanism for moving the workpiece located on it, a working chamber and a working head - a bracket that carries two mutually centered supports for fixing tool electrode, of which the top with a nozzle nozzle, ensuring the alignment of the electrolyte stream and the electrode tool, and the bottom with a mechanism, according to the invention, the electrode-tool is made in the form of a fixed cross-sectional elastic plate fixed at both ends with a substantially different ratio of overall dimensions in the direction of the axis of symmetry, the supports for fixing the electrode-tool are capable of synchronous and / or / independent rotation from individual drives, and the upper part of the working head is a half-bracket made with the possibility of reinstalling and / or / carrying out the working feed in the direction of the longitudinal axis of the electric ode-tool from a separate drive.

In addition, according to the invention, the movement mechanism of the workpiece contains a table driven by a two-axis planar servomotor in the form of two spaced support strips.

In addition, according to the invention, the working head - the bracket is mounted on a gimbal suspension with the possibility of independent tilt of the longitudinal axis of the electrode-tool in two mutually perpendicular planes, with a single center of rotation located at the level of the working surface of the table support strips.

In addition, according to the invention, low-inertia servomotors can be used as motors for supporting the rotation of bearings for securing the tool electrode, with the possibility of controlling the torsion angles of the tool electrode and limiting the occurring torque on the motor shaft.

In addition, according to the invention, the electrical insulation and kinematic connection of the engines with supports for fixing the electrode-tool can be provided by a gear-belt transmission.

In addition, according to the invention, electrical insulation and centering of the supports for securing the electrode-tool can be provided in pairs with duplexed angular contact bearings with ceramic rolling bodies with the possibility of compensating for the runout of the supports when fixing the electrode-tool.

In addition, according to the invention, the contact rings of the current supply can be mounted on each support for fixing the electrode-tool.

In addition, according to the invention, the mechanism of tension of the electrode-tool of the lower support can be equipped with an electromechanical drive and a sensor for monitoring the tension force.

In addition, according to the invention, the supply of electrolyte to the upper support can be provided using a rotary coupling.

In addition, according to the invention, in order to protect the lower support from penetration of the electrolyte, compressed air is supplied by means of a rotary coupling.

In addition, according to the invention, the longitudinal axis of the electrode-tool may not coincide with a parallel axis of rotation.

The problem is solved, and the technical result is also achieved by the power source of the machine for electrochemical processing with a rotating non-profiled electrode tool containing a stabilized voltage source and an electronic switch, which, according to the invention, contains a high-speed analog-to-digital converter and a voltage setting correction circuit combining the key control function moreover, the inputs of the analog-to-digital converter are connected directly to the load, and the output to the input of the circuit to rrektsii voltage setting, the outputs of the voltage setting correction circuit connected to the input of a controlled source of stabilized voltage input to the key management and to the input of the measurement start analog-to-digital converter.

The invention is illustrated by drawings.

In FIG. Figure 1 shows the waveforms of changes in current and voltage on the interelectrode gap with a surge of voltage along the leading edge of the pulse.

In FIG. Figure 2 shows the waveforms of changes in current and voltage on the interelectrode gap with a surge of voltage along the trailing edge of the pulse.

In FIG. 3 shows a direct-current groove slotting circuit with a displacement (relative rotation) of the initial and final cross sections of the tool electrode.

In FIG. Figure 4 shows the groove slotting scheme without shifting the initial and final sections (without twisting the plate) with the inclusion of the operating voltage pulse, carried out in a phase depending on the direction of the electrode's velocity vector V.

In FIG. 5 shows a diagram of the implementation of groove cutting in a pulsed mode.

In FIG. 6 is a diagram of a second passage in a pre-cut groove.

In FIG. 7 shows a general view of the machine.

In FIG. 8 shows the upper support of the electrode-tool.

In FIG. 9 shows the lower support of the electrode-tool.

In FIG. 10 shows a diagram of a power source.

In FIG. 11 shows a schematic of an electronic key.

The essence of the method is as follows.

To ensure the accuracy of processing, it is necessary to ensure the stability of the properties of the interelectrode medium along the length of the MEP, which can be caused by an increase in gas filling or boiling of the electrolyte, or the appearance of cavitation cavities.

Cavitation phenomena arise for reasons related to the nature of the movement of the electrolyte flow in the MEP sections having small radii of curvature of the streamlined surfaces at relatively high fluid velocities. For example, this is possible with a high frequency of rotation of the electrode-tool, or a high inlet pressure and a large MEZ, etc. Cavitation cavities (cavities) are filled with electrolyte vapors and gas and, as a rule, arise before a current pulse is applied, at relatively large gaps. With a decrease in the rate of relative movement of the electrolyte, for example, by reducing the MEZ, reducing the inlet pressure, etc. action - cavitation cavities may disappear. Their appearance leads to an increase in the electrical resistance of the MEA, which can be detected by analyzing the shape of the current pulses and the voltage on the MEA. So, for example, the occurrence of cavitation is controlled by a sharp, higher empirically determined setpoint - R _cav , by an increase in the electrical resistance of the interelectrode gap along the leading edge of the pulse (Fig. 1). As the setting R _cav , the electric resistance of the MEP at the leading _{edge of the} pulse at low electrolyte pumping rates can be taken. Those. at pumping speeds at which the change in speed does not affect the MEP resistance along the leading edge of the pulse. It should be borne in mind that the measurement of the MEP resistance is performed after the completion of transient electrical processes in the power circuit of the power source. When cutting grooves in parts of constant thickness, the angle of inclination of the helical line is set so as to ensure the angle of inclination of the longitudinal patterns on the side surface to the axis of the electrode-tool in the range of 50 ... 70 degrees.

An increase in gas filling or boiling of an electrolyte is a consequence of the passage of current through the electrolyte in the MEP. The intensity of these processes increases at the stage of an increase in the MEZ. Their consequence is also an increase in the electrical resistance of the MEA, which can be detected by analyzing the shape of the current pulses and the voltage on the MEA. So, for example, the occurrence of the limiting gas filling and boiling of the electrolyte is controlled by a sharp, higher than the empirically determined setting R _ags , an increase in the electrical resistance of the interelectrode gap along the trailing edge of the pulse (Fig. 2).

Thus, the limitation of the helix inclination angle and the limitation of the highest EI rotation frequency and the minimum MEZ (determined by the feed rate) can be determined by an indirect parameter - the electric resistance of the MEA at the leading and trailing edges of the pulse. In this case, the processing process is carried out at the optimum angle of inclination of the helix of the risks, the maximum possible feed rate and the frequency of rotation of the EI, at which there are no values of the electric resistance of the MEP along the leading and trailing edges of the pulses exceeding the specified ones. The MEP resistance can be taken as the setting, at which the operating current decreases by more than 80%, which corresponds to the maximum permissible gas filling of the MEP.

In some cases, it may turn out to be convenient to use not the absolute values of the resistance settings, but relative equivalents, for example, the ratio of the resistances along the leading (trailing) edge to the minimum MEP resistance in a pulse.

When grooving a groove in the constant operating voltage mode (Fig. 3), the initial and final cross sections of the electrode-tool, made in the form of a plate, are rotated relative to each other by an angle γ, providing screw twist of the plate. The electrolyte is supplied along the longitudinal axis of the electrode-tool, after which the rotation of the electrode-tool is started, a constant operating voltage is applied and the electrode-tool is moved along a predetermined path with a given speed. The presence of a screw twist of the plate contributes to a more intensive movement of the electrolyte along the axis of the electrode-tool, due to which the conditions for the evacuation of dissolution products from the interelectrode gap are improved. During processing, the value of the twist angle γ can be rapidly changed to correct the hydrodynamic conditions of the environment of the interelectrode gap, for example, when the thickness of the cut workpiece is changed.

When grooving a groove in a pulsed mode (Fig. 4), the supply of a pulse of the operating voltage is carried out synchronously with the rotation of the electrode-tool, made in the form of a plate of rectangular cross section, without creating a twist. One of the two narrow edges of the electrode-tool is accepted as working. During periods of time free from the supply of operating voltage, due to the rotation of the electrode-tool, the interelectrode medium is updated and reaction products are evacuated. The operating voltage pulse is switched on in the phase ϕ ₀ + 2π⋅n, see Fig. 5 (n is the number of revolutions), which depends on the direction of the electrode velocity vector V, the shutdown is performed in the phase ϕ ₁ + 2π⋅ (n + 1), and the condition 2π⋅ϕ ₀ = ϕ ₁ is satisfied, the position of the electrode is taken as the zero angular position when the axis of symmetry of the cross section parallel to the larger side coincides with the velocity vector, while the working face of the electrode forms a minimum interelectrode gap S _min with the surface of the part.

Thus, the switching on of the operating voltage pulse occurs at the moment when the axis of symmetry of the cross section parallel to the larger side forms an angle ϕ = 2π-ϕ ₀ = ϕ ₁ with the feed vector of the electrode-tool, called the angle of switching on the pulse, turning off after turning the tool by 2⋅φ angle (relative to the moment of inclusion), respectively, the voltage pulse duration depending on the rotational speed of the electrode-tool: t _and = φ / π⋅ω, where ω - the angular velocity. The angle ϕ determines the intensity of the dissolution process and affects the accuracy and width of the groove at a given speed of movement of the electrode-tool. With increasing values of the angle ϕ, the width of the slot to be cut increases, while decreasing the value of the angle ϕ, the groove becomes narrower. The limits for changing the values of the angle of inclusion of the voltage are limited to an interval from 0 to 90 degrees, since at values of the angle of inclusion greater than 90 degrees, the effects associated with this processing method disappear. For one revolution of the electrode-tool, two pulses can be supplied, in the first and second half-cycles of rotation, due to the symmetry of the electrode (in this case, both narrow edges of the electrode are accepted by the workers), also, under too unfavorable conditions for updating the interelectrode medium, it is possible to apply one pulse per a few revolutions.

For certain values of the feed speed of the electrode-tool, the ratio of the sides of its cross section and the angle of inclusion of the voltage ϕ, the width of the slot to be cut may be equal to the length of the diagonal section, in this case, when turning, in the phase close to ϕ ₂ , the contact of the electrodes will occur, while the supply of the electrode-tool is stopped, which resumes if there is no contact during the next revolution.

When making the second pass in a groove previously cut under high-performance modes (Fig. 6), the operating voltage pulses are supplied synchronously with the rotation of the tool electrode, as well as when grooving the groove in a pulsed mode, but with a shift of the on phase ϕ ₀ and off phase ϕ ₁ , 90 degrees relative to the feedrate velocity vector towards the surface of the groove that is being cleaned.

The state of the interelectrode medium and the efficiency of the process of evacuation of dissolution products from the interelectrode gap are monitored by changing the conductivity, for which the processing is interrupted, namely, the operating voltage pulses are turned off and the electrode is stopped (without stopping its rotation) for the time required to completely update the interelectrode environment, after which the operating voltage pulses are turned on, the current is measured in each pulse and the average conductivity is calculated, from pulse to pulse n ovodimost reduced to its stabilization, to minimize the difference between clean and cluttered intervals conductivity change-speed tool electrode and / or electrolyte velocity of the jet emerging from the nozzle.

To implement the method proposed a new design of the machine. The machine (Fig. 7) contains a frame 1, on which a two-axis planar servo drive 2 of the cantilever table 3 moving mechanism is mounted for mounting and securing the workpiece 4. In the working chamber 5, on the uniaxial supports 6, 7, a frame 8 is mounted on which the support 9 the working head-brackets 10 carrying the electrode-tool 11. The arrangement of the supports 6, 7 and 9 corresponds to the gimbal, and the change in the angle of the longitudinal axis of the electrode-tool in two, required for cutting the product with an inclined generatrix mutually perpendicular planes is provided by the corresponding rotation of the half frame 8 and the working head-clamp 10, carried out by servomotors 12, 13. Located on the ends of the working head-clamp 10, the upper 14 and lower 15 supports for mounting the electrode-tool are made with the possibility of synchronous or independent rotation from individual drives with servomotors 16, 17. The upper part of the bracket 10 is movable with the ability to change the distance between the upper support 14 and table 3 in accordance with the height of the workpiece 4. The possibility of working feed in the case of cantilever fastening in the upper support 14 of the electrode of the tool 11, for example, when flashing holes, is provided from a separate drive with a servomotor 18.

The upper support of the electrode-tool (Fig. 8) contains a hollow spindle 20 rotated by the pulley 19, mounted on two spaced apart duplex angular contact bearings 21 with ceramic, for electrical insulation, rolling elements. An eccentric sleeve 22 with a collet clamp is installed in the spindle bore, at the end it secures the electrode-tool with the required cross-sectional configuration and its necessary centering. The system of mounting holes at the end of the eccentric sleeve 22 and the nozzle 23 allows you to change their relative angle of rotation and to form the electrolyte supplied through the rotary coupling 24 into a stream coaxial with the electrode-tool. The current supply to the spindle or rather the support of the electrode-tool is provided by a rotating contact device 25.

The lower support of the electrode-tool (Fig. 9) consists of a hollow spindle 27 driven by a gear belt drive 26 mounted on angular contact bearings 28 with ceramic rolling bodies. The electrode-tool is mounted in the spindle with a collet clamp 29. In order to ensure the required electrode-tool tension, the housing of the spindle assembly 30 is axially movable in the guide sleeve 31, which is carried out and controlled by the electromechanical actuator 32 through the lever 33 according to the magnitude of the tension force. To protect against electrolyte leakage through the slots of the collet clamp 29, compressed air is supplied to the hollow spindle 27 through the rotary coupling 34. The current supply to the spindle of the lower support of the electrode-tool is provided by a rotating contact device 35.

To implement the method, a new power source is also proposed (Fig. 10), capable of operating both in constant voltage mode and in pulse current mode with good voltage stabilization and with the ability to control the duration and phase of the pulse. The power supply with the specified properties is built on the basis of an adjustable voltage regulator with a transistor switch. Such power sources are used in electrochemical processing. The stabilized voltage source 36 maintains a constant predetermined voltage across the capacitor 37. The electronic switch 38 opens at the right time and creates a voltage pulse at the load 39. The advantage of such a power source is its complete controllability in terms of voltage, pulse duration, and phase of pulse supply. It is worth noting that the creation of such a power source does not constitute a difficult technical task up to a current that does not exceed the permissible current of one transistor (up to several hundred amperes), which is quite sufficient for the proposed method.

The disadvantage of such a power source is that the voltage is controlled to an electronic switch, a variant (special case) of the circuit of which is shown in FIG. 11. As the switching element, a transistor 40 is used, for example, a MOS transistor. To protect the transistor 40 from overload, a current sensor 41, for example a resistor, is installed in the power circuit. The driver 42 is designed to convert the control signal into a signal of the required level to control the transistor 40 and controls the current, preventing it from exceeding the permissible value. Depending on the driver circuit, the voltage drop across the resistor at maximum current can be from 0.2 to 0.7 V. Transistor 40 is also not an ideal switch and voltage from a few millivolts at minimum current and up to 2-3 V can drop on it. maximum current. There is also a voltage drop on the wires connecting the power source to the load. Thus, the voltage at the load may differ from the set by an amount unacceptable for the proposed method (up to 4 volts). Moreover, this value depends on the current and cannot be taken into account and compensated in advance.

In order to increase the accuracy of voltage stabilization of a switching power supply, consisting of a stabilized power supply 36 and an electronic switch 38, a voltage setpoint correction circuit 43 is added to the circuit, which combines the electronic key control functions and a high-speed analog-to-digital converter (ADC) 44, with the inputs of the analog-to-digital converter connected directly to the load (interelectrode gap), and the output to the input of the voltage setting correction circuit 43. The circuit outputs correction settings voltage 43 are connected to the input of a controlled source of stabilized voltage, to the control input of the electronic switch 38 and to the input of the measurement start of the analog-to-digital Converter 44. The machine operates as follows.

For electrochemical cutting of a closed loop in the workpiece blank 4, a technological hole is pre-flashed, the center of which by repositioning the table 3 is aligned with the intersection point of the axis of the supports 6, 7 of the half frame 8 and the support 9 of the working head-bracket 10. Passed through the technological hole and fixed in the upper 14 and the lower 15 supports of the working head 10, the electrode-tool 11 is controlled by relative rotation of the spindles 20, 27 is twisted (if necessary) by a given angle, and by moving the casing of the spy fittings assembly 30 actuator 32 carried out its tension. After turning on the synchronized rotation of the spindles 20, 27 kinematically connected with the servomotors 16, 17, feeding the electrolyte through the nozzle 23 using the rotary coupling 24 and supplying the process current through the slip rings 25, 35, program-controlled movement of the table 3 and a change in the angle of inclination of the longitudinal axis electrode-tool 11 in two mutually perpendicular planes is the process of cutting.

For flashing holes in the upper support 14 of the working head - brackets 10, the electrode-tool 11 is fixed. After setting the required angle of inclination of the longitudinal axis of the electrode-tool, turning on the spindle 20, feeding the electrolyte using the rotary coupling 24 and supplying the technological current through the contact ring 25 of the working by feeding the upper movable part of the bracket 10, the working end of the electrode-tool 11 is fed into the workpiece 4.

For processing blind grooves and complex spatial surfaces by electrochemical milling with a non-profiled electrode-tool 11, the kinematics of the executive movements used when flashing holes is supplemented by movements of the table 3.

The power source operates as follows. At the right time, the voltage setpoint correction circuit 43 gives a signal to turn on the electronic switch 38, and after a while the signal to start the ADC 44. After the electronic switch is turned off, a voltage setpoint correction circuit 43 compares the measured value of the voltage at the load with the set voltage value and changes the setting of the stabilized voltage source by the value of the difference between the specified voltage and measured. By the beginning of the next pulse, the stabilized voltage source 36 maintains the voltage across the capacitor 37 higher than that set on the load by the magnitude of the voltage drop across the electronic switch 38 and the wires. Each pulse takes a new measurement, and the value of the stabilized voltage is adjusted depending on the changing current.

Thus, the proposed power source of the machine for electrochemical processing generates at its output a stabilized constant voltage or voltage pulses, consistent with the phase of rotation of the electrode-tool.

Concrete implementation example

The proposed method of electrochemical processing is implemented on a universal copy-stitching electrochemical machine, equipped with: a device for mounting a plate EI, a workpiece feed drive, a working chamber, an electrolyte supply and regeneration system, a switching power supply and a control system made according to this invention.

The electrode tool is made of chromium-nickel stainless steel and was a long elastic plate of constant cross-section with overall dimensions in the direction of the axis of symmetry: 0.25 and 0.12 mm.

The billet electrode (part) was a bar of 10 mm thick Stavax chrome steel.

As an electrolyte, a 10% aqueous solution of NaNO _{3 was used} . The temperature of the electrolyte is 20 ° C.

The electrolyte pressure at the inlet to the nozzle is 6 bar.

In accordance with the proposed method, voltage pulses with an amplitude of 12 V and a duration of 1000 μs were periodically applied to the interelectrode gap periodically, synchronously with the phase of the closest approach of the electrodes, while the rotation frequency was 49 Hz and the angle ϕ was equal to 18 °. In this case, a critical increase in the gas filling of the electrolyte was controlled by a sharp increase in the electrical resistance of the interelectrode gap along the trailing edge of the pulse.

Under these conditions, during electrochemical grooving of the groove, a feed rate of 0.2 mm / min was achieved, the error in the shape of the groove (difference in groove width at the inlet of the electrolyte and the outlet) was 20 μm, and the surface roughness was Ra 0.4 μm.

So, the claimed invention allows to expand the functional and technological capabilities, to increase the accuracy of complex contouring and surface quality, as well as to provide a large depth of cutting slots and grooves with variable angles of inclination of the generatrix.

Claims (26)

1. The method of electrochemical treatment with a rotating non-profiled electrode-tool, including the supply of electrolyte to the treatment zone through a nozzle, characterized in that the processing is carried out by multi-axis movement in several successive transitions by the electrode-tool, made in the form of a long elastic plate fixed at both ends of a constant cross section with a significantly different ratio of overall dimensions in the direction of the axes of symmetry rotating around the longitudinal axis, the first the transition is carried out at a constant voltage, while the axis of the initial and final cross sections of the same name of the plate are rotated relative to each other, around the longitudinal axis, by a certain angle of shift γ, ensuring the creation of a helical twist of the electrode-tool, and the subsequent transitions are carried out in the groove previously obtained at the first transition, while voltage pulses are supplied synchronously with the rotation of the electrode-tool and with a shift in the phase of switching on the pulse and phase off of the pulse by 90 degrees flax of the feed rate vector in the direction to the surface of the groove to be cleaned. 2. The method according to p. 1, characterized in that the width of the slot to be cut is changed by adjusting the angle of the voltage pulse ϕ, and as the angle of the voltage pulse ϕ increases, the width of the groove b increases, and when the angle of the voltage pulse ϕ decreases, the groove width b decreases. 3. The method according to p. 2, characterized in that when the width of the groove is reduced to the length of the long side of the cross section of the electrode-tool when a contact occurs between the electrode-tool and the workpiece, the supply of the electrode-tool is stopped for a period of revolution. 4. The method according to p. 3, characterized in that they control the occurrence of cavitation in the interelectrode space by a sharp, above empirically determined, increase in the electrical resistance of the interelectrode gap along the leading edge of the pulse. 5. The method according to p. 3, characterized in that they control a critical increase in gas filling of the electrolyte by a sharp, above empirically determined, increase in the electrical resistance of the interelectrode gap along the trailing edge of the pulse. 6. The method according to p. 1, characterized in that the rotation frequency and the twist angle of the electrode-tool change, and with increasing thickness of the part, reduce the twist of the electrode-tool and increase the number of revolutions without crossing the threshold for cavitation in the interelectrode space along the entire length of the electrode -instrument, and with a decrease in the thickness of the part, increase the twist of the electrode-tool and reduce the frequency of its rotation, while ensuring sufficient conditions for the evacuation of products of electrochemical reactions from the interelectrode space, not allowing a critical increase in gas filling or boiling of electrolyte. 7. The method according to p. 1, characterized in that when machining a part with an inclined generatrix to obtain a given part size, the axis inclination of the tool electrode is adjusted in accordance with the magnitude and sign of the difference in the velocity of the supply vectors of the electrode tool in its initial and final section, so so that with a positive value of the difference in the velocities of the supply vectors, the inclination of the axis of the electrode-tool relative to the vertical axis of the machine is increased, and if it is negative, it is reduced. 8. A method of electrochemical treatment with a rotating non-profiled electrode-tool, comprising supplying the electrolyte to the treatment zone through a nozzle, characterized in that the processing is carried out by multi-axis movement in several consecutive transitions by the electrode-tool, made in the form of a long elastic plate fixed at both ends of a constant cross section with a significantly different ratio of overall dimensions in the direction of the axes of symmetry rotating around the longitudinal axis, the first transition carried out at a pulse voltage, without pre-twisting the plate at a shear angle γ = 0, while changing the phase of the voltage pulse or a group of voltage pulses in each revolution of the electrode-tool, depending on the direction of the supply vector, ensuring the inclusion of a pulse or group of pulses at a time when the axis of symmetry parallel to the long side of the cross section of the electrode-tool forms a predetermined angle ϕ with the feed vector less than 90 degrees, and the voltage is turned off after turning the electrode-inst the angle at the angle 2ϕ from the moment of switching on, and subsequent transitions are carried out in the groove previously obtained at the first transition, while voltage pulses are supplied synchronously with the rotation of the tool electrode, as well as when cutting the groove at the pulse voltage, and with the shift of the pulse switching phase and the phase off pulse by 90 degrees relative to the feedrate vector in the direction of the processed clean surface of the groove. 9. The method according to p. 8, characterized in that the width of the slot to be cut is changed by adjusting the angle of the voltage pulse ϕ, and as the angle of the voltage pulse ϕ increases, the width of the groove b increases, and when the angle of the voltage pulse ϕ decreases, the groove width b decreases. 10. The method according to p. 9, characterized in that when reducing the width of the groove to the length of the long side of the cross section of the electrode-tool when a contact occurs between the electrode-tool and the workpiece, the supply of the electrode-tool is stopped for a period of revolution. 11. The method according to p. 10, characterized in that they control the occurrence of cavitation in the interelectrode space by a sharp, above empirically determined, increase in the electrical resistance of the interelectrode gap along the leading edge of the pulse. 12. The method according to p. 10, characterized in that they control a critical increase in gas filling of the electrolyte by a sharp, higher empirically determined, increase in electrical resistance of the interelectrode gap along the trailing edge of the pulse. 13. The method according to p. 8, characterized in that the rotation frequency and the twist angle of the electrode-tool change, and with increasing thickness of the part, reduce the twist of the electrode-tool and increase the number of revolutions without crossing the threshold for cavitation in the interelectrode space along the entire length of the electrode -instrument, and with a decrease in the thickness of the part, increase the twist of the electrode-tool and reduce the frequency of its rotation, while ensuring sufficient conditions for the evacuation of products of electrochemical reactions from the interelectrode space, not allowing a critical increase in gas filling or boiling of electrolyte. 14. The method according to p. 8, characterized in that when processing a part with an inclined generatrix to obtain a given part size, the inclination of the axis of the electrode-tool is adjusted in accordance with the magnitude and sign of the difference in the velocities of the feed vectors of the electrode-tool in its initial and final sections, in this case, with a positive value of the difference in the velocities of the supply vectors, the inclination of the axis of the electrode-tool relative to the vertical axis of the machine is increased, and if it is negative, it is reduced. 15. A machine for electrochemical processing with a rotating non-profiled electrode-tool, containing an electrolyte supply system, a power source, a bed with a mechanism for moving the workpiece located on it, a working chamber and a working head-bracket carrying two mutually centered supports for fixing the electrode-tool, of which upper with nozzle-nozzle, ensuring the alignment of the jet of electrolyte and the electrode-tool, and the lower with a mechanism that regulates its tension, characterized in that the electrode The strument is made in the form of a fixed cross-section of an elastic plate fixed at both ends with a substantially different ratio of overall dimensions in the direction of the axis of symmetry, the supports for fixing the electrode-tool are made with the possibility of synchronous and / or / independent rotation from individual drives, and the upper part of the working head the half-bracket is made with the possibility of reinstalling and / or carrying out a working feed in the direction of the longitudinal axis of the electrode-tool from a separate drive. 16. The machine according to p. 15, characterized in that the mechanism for moving the workpiece contains a table driven by a two-axis planar servomotor in the form of two spaced support strips. 17. The machine according to p. 15, characterized in that the working head-bracket is mounted on a gimbal suspension with the possibility of independent tilt of the longitudinal axis of the electrode-tool in two mutually perpendicular planes, with a single center of rotation located at the level of the working surface of the table support strips . 18. The machine according to p. 15, characterized in that the low-inertia servomotors are used as the motors for supporting the rotation of the supports for fixing the electrode-tool, with the ability to control the twist angles of the electrode-tool and limit the resulting torque on the motor shaft. 19. The machine according to p. 15, characterized in that the electrical insulation and kinematic connection of the engines with supports for fixing the electrode-tool is provided by a gear-belt transmission. 20. The machine according to p. 15, characterized in that the electrical insulation and centering of the supports for fixing the electrode-tool is provided in pairs with duplexed angular contact bearings with ceramic rolling bodies with the possibility of compensating for the runout of the supports when fixing the electrode-tool. 21. The machine according to p. 15, characterized in that the contact rings of the current supply are mounted on each support to secure the electrode-tool. 22. The machine according to p. 15, characterized in that the mechanism of tension of the electrode-tool of the lower support is equipped with an electromechanical drive and a sensor for monitoring the tension force. 23. The machine according to p. 15, characterized in that the supply of electrolyte to the upper support is provided using a rotary clutch. 24. The machine according to p. 15, characterized in that in order to protect the lower support from the penetration of the electrolyte, compressed air is supplied using a rotary coupling. 25. The machine according to p. 15, characterized in that the longitudinal axis of the electrode-tool may not coincide with the axis of rotation parallel to it. 26. The power source of the machine for electrochemical processing by a rotating non-profiled electrode-tool, containing a controlled stabilized voltage source and an electronic switch, characterized in that it contains a high-speed analog-to-digital converter and a voltage setting correction circuit that combines the key control function, and the analog-digital inputs the converter is connected directly to the load, and the output to the input of the voltage setting correction circuit, while the outputs of the correction circuit Voltage Settings are connected to the input of a controlled source of stabilized voltage input to the controllable switch and to the trigger input of analog-digital converter.

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