Procedure for control of spark gap during vacuum arc melting and facility for implementation of this procedure

FIELD: metallurgy.

SUBSTANCE: invention refers to specific electro-metallurgy, particularly to vacuum arc re-melting of high reaction metals and alloys and can be implemented at melting ingots out of titanium alloys. The procedure for control consists in determination of actual value of a spark gap and in adjusting position of a consumable electrode relative to a melted ingot by results of arc voltage measurements, in successive selection of current pulses of reverse polarity and in measuring their duration. An interface and normalising block regulating an input signal to a specified value at bandwidth 50 kHz is arranged in the installation. A computer recognises voltage pulses of reverse polarity and duration in a specified range at sampling frequency not less, than 40 kHz.

EFFECT: upgraded accuracy of measurement.

2 cl, 2 dwg, 1 ex

 

The invention relates to the field of special electrometallurgy, namely, vacuum arc melting highly reactive metals and alloys, and can be used in the melting of ingots from titanium alloys.

The main control parameters of the vacuum arc melting (var) are: maintaining a stable arc current, the interelectrode gap and the pressure in the furnace. Properly selected and maintained these parameters in a stationary regime melting exert a decisive influence on the structural and chemical homogeneity of the metal. Of these options, the most difficult to control is the interelectrode gap as directly producing its measurement is extremely difficult. Therefore, modern management system of var as a measure of the determination of the interelectrode gap using indirect parameters such as the voltage drop across the arc and the frequency of drip closures. The quality management of the var process requires finding and using data that contains reliable information about the magnitude of the interelectrode gap.

The known method of vacuum arc remelting ingots of titanium alloys, including the measurement of arc voltage with obtaining a controlled voltage signal, the analysis of its changes, the adjustment of athodoemeri electrode relative to the melted ingot. Voltage measurement is done with a frequency of not more than 1000 Hz, followed by separation of the signals in arc voltage with a frequency of 300 and/or 600, and/or 900 Hz and the definition of the interelectrode gap (patent RU 2278176 C1, publ. 20.06.2006).

The disadvantage of this method is the dependence of the frequency of the monitored signal from the frequency of operation of the system pulse-phase control power supply of the furnace of the SDT. Changing the frequency of operation of the system pulse-phase control source will cause an error in determining the magnitude of the arc gap at low values of current.

The closest analogue to the claimed invention is a method of control and regulation of the interelectrode gap during vacuum arc melting, including the measurement of arc voltage with obtaining a controlled voltage signal, the analysis of its changes and adjustments to the consumable electrode relative to the melted ingot (patent RU 2227167, publ. 20.04.2004) prototype.

The disadvantage of this method is complex circuit device to control the interelectrode gap during vacuum arc melting.

A device in the method of vacuum arc remelting ingots with the maintenance of the interelectrode gap parameters frequency drip zamyka the rd. Patent US 4578795 from 25.03.1986, Stenzel and F.-C. Thomas - prototype. The control device includes a voltage sensor, a comparator, a microprocessor, a controller-the controller and the drive.

A disadvantage of the known device are possible errors in the evaluation of the interelectrode gap due to noise imposed on the signal short drip circuits and cause errors in the estimation of the interelectrode gap.

The aim of the present invention is to provide a method of control of the interelectrode gap in the range 560 mm and a transfer control electrode holder during vacuum arc-melting device for its implementation.

The problem is solved in that in the method of control and regulation of the interelectrode gap during vacuum arc melting, including the measurement of arc voltage, obtaining a controlled voltage signal, the analysis of its changes, the definition of it the actual interelectrode gap and regulating the position of the consumable electrode relative to the melted ingot, the measuring voltage is produced with a frequency of not less than 40 kHz, and as a controlled voltage signal using the selected pulse voltage with a reverse polarity voltage and a duration of 0.15 MS.

This result in the implementation of the image is etenia is achieved by the device control and regulation of the interelectrode gap during vacuum arc melting, containing analog-to-digital Converter, the computer and the drive electrode with a proportional-integral controller with block mates and normalization of the input signal characterizing the arc voltage to a certain value at a bandwidth of 50 kHz, and the computer made with the possibility of the selection pulse voltage with a reverse polarity and a duration within the specified range at a frequency of not less than 40 kHz.

The block diagram of the device shown in figure 1, and figure 2 - chart recording of voltage on the arc.

The device includes: unit 1 - unit, normalizing the arc voltage signal with a bandwidth of at least 50 kHz; block 2 (ADC) - high-speed analog-to-digital Converter with a sampling frequency not lower than 40 kHz; block 3 (PC) - industrial computer that implements the algorithm of computer processing (programmatically determines the magnitude of the interelectrode gap and control the movement of a consumable electrode); block 4 - drive movement of a consumable electrode; block 5 - vacuum arc furnace.

The device operates as follows. When a signal voltage unit 1 normalizes the input signal to a certain value, while performing the role of filters bandwidth of at least 50 kHz. Further, through the ADC signal in the industrial computer and subjected to computer processing according to a certain algorithm, calculates the magnitude of the interelectrode gap and a command is issued to the actuator 4 to move the consumable electrode vacuum arc furnace 5.

The method of control is implemented as follows. There is a permanent measurement of arc voltage with a frequency of at least 40 kHz. This frequency is optimized for use regulators working on the pulses of short circuits, because the minimum pulse width should be not less than 0.1 MS, during which the signal voltage with reverse polarity. Shorter pulses do not carry useful information. To ensure this polling frequency (40 kHz) block normalization has a bandwidth of 50 kHz.

Converted in blocks 1 and 2 the signal is sent to the system computer processing, where for a given algorithm is the selection of the signal characteristic of the pulses. Under the characteristic pulses are understood to be present in the voltage signal furnace pulses with opposite polarity (when the anode is a bar, and a cathode - consumable electrode), i.e., pulses with a voltage of less than 0 V, and a duration in the range 0.15,0 MS (figure 2). From the characteristic of the pulses is cutoff "Sumava the pulses, which are not informative. Of the remaining pulses in accordance with the Weibull distribution is picking the most important informative in terms of pulses, which in the following are averaged at a certain time interval. Averaging is exposed to the duration of the selected pulse. The resulting signal on the predetermined experimental data allows to calculate the amount of actual interelectrode gap with an accuracy of 5 mm In the future to provide a control signal to the actuator moving consumable electrode is used, the algorithm is a standard PI controller (proportional-integral controller). The coefficients of the PI controller is chosen experimentally taking into account the actual speed of melting at currents less than 10 kA. PI controller compares the actual value of the interelectrode gap with the desired setting value of the interval, and generates a control signal to the actuator for moving consumable electrode vacuum arc furnace.

An example of a specific implementation.

The melting of the consumable electrode was carried out in a vacuum arc furnace DTV-G equipped with a control system of the heat.

For consumable electrode alloy Ti-10V-2Fe-3Al diameter of 690 mm, length 2100 mm cutter was made token (longitudinal Cana is ka 120 mm) for fixing the beginning of the elimination of shrinkage of the shell (voor). The electrode was loaded into the mold with a diameter of 770 mm After loading and alignment of the electrode made its welded to the candle. The furnace was evacuated and turned on the power source. Next were melting process within 36 hours for a given technology with the control and management of the movement of the electrode holder on the basis of the signals characteristic of the pulses. After melting the setup value of the interelectrode gap should be 24 mm; in fact, the measured interelectrode gap was 22 mm

Proposed method of control vacuum arc melting in comparison with the known allows you to effectively monitor and regulate the interelectrode gap is within 560 mm regardless of the frequency of operation of the system pulse-phase control power supply of the furnace SDT with a simplified hardware diagram of a device for monitoring the interelectrode gap during vacuum arc melting.

1. The method of control and regulation of the interelectrode gap during vacuum arc melting, including the measurement of arc voltage, obtaining a controlled voltage signal, the analysis of its changes, the definition of it the actual interelectrode gap and regulating the position of the consumable electrode as in plusimage ingot, characterized in that the measuring voltage is produced with a sampling frequency of at least 40 kHz, and as a controlled voltage signal using the selected pulse voltage with a reverse polarity voltage and a duration of 0.15 MS.

2. Device control and regulation of the interelectrode gap during vacuum arc melting, containing analog-to-digital Converter, the computer and the drive movement of the electrode with a proportional-integral regulator, characterized in that it is provided with a connection unit and the normalization of the input signal characterizing the arc voltage to a certain value at a bandwidth of 50 kHz and with a selectable pulse ECM voltage with a reverse polarity and a duration within the specified range when the sampling frequency is not less than 40 kHz.



 

Same patents:

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy field and can be used for operation of arc furnace, containing at least one electrode. In the method it is implemented tapping stage, at that at least to one electrode during the time being in switched on condition (t'3, t'f, t"f) it is input energy, and during the time being in off mode (t'03, t'04> t"04) the energy is not input. Herewith the beginning of tapping stage (T'TO) fall on the least being time on state (t'f, t"f). Herewith to at least one electrode energy at least from time to time is input also during the tapping stage. Adjusting device contains model for energy balance and mass and is implemented with ability of regulation of electrode position and input of energy to it. Invention provides tapping to start earlier than at usual running regime of arc furnace that leads to considerable advantage by time, reduction of energy consumption and electrodes, and also of more efficiency. Preliminary calculation of changing the energy content of melt material during the time of tapping stage provides desirable energy content of raw steel and counteracts the risk of its overheating.

EFFECT: receiving of ability tapering to start earlier, than at usual running regime of arc furnace that leads to considerable advantage by time, reduction of energy consumption and electrodes, and also of more efficiency.

16 cl, 3 dwg

FIELD: electrometallurgy.

SUBSTANCE: method consists in the control of reactive power of two and more arc furnaces by means of its sequential start into simultaneous operation, at that distance of proposed priority is defined by means of formula and depends on melt average duration, melting average duration, finishing average duration, average deviation of melting process, average duration of furnace downtime.

EFFECT: productivity improvement and decreasing of electricity specific consumption, reduction of negative impact of furnaces group to supply mains.

1 dwg, 1 ex, 1 tbl

FIELD: metallurgy.

SUBSTANCE: invention concerns electroslag remelting and can be used in mode controllers of electroslag furnace. Method includes control of operating current and definition by its modulated curve of formation moment of drop on the end of electrode. Smelting is implemented in pulsed operation by means of current interruption at the moment of drop of liquid metal initiation on the end of electrode, defining by curve of flux bath active resistance, with creating operational current pause of duration equal to time of tip leakage at purely thermal process of electrode burn-off and further rising of current till operating value after breakaway of the first drop and at the moment of further drop formation. Facility is additionally outfitted by three-input block of meter of tip leakage electrode metal into no-current condition, containing of electronic switch, constant-current source, voltage inverter and second threshold element. Invention provides rising of electroslag remelting efficiency and quality of ingot metal by means of drops breakage of electrode metal at the moment of its formation on electrode.

EFFECT: productivity improvement of electroslag remelting and metal quality.

3 cl, 2 tbl, 2 dwg

FIELD: metallurgy.

SUBSTANCE: invention refers to electrothermics, particularly to automated position regulators of electrodes of electric arc steel smelting furnaces. According to the invention for each phase of the electric arc furnace the regulator contains a setting power mechanism, a unit of a dead band, an output of which is connected with the input of controlled reverse converter, to the output of which an electric engine of electrode travel is connected, and a threshold component, the output of which is connected to the control input of a controlled switch. The regulator is equipped with a magnifier, with a limit unit, an aperiodic filter, a summator and a unit for separation of error signal module, the output of which is connected to the input of the threshold component, while the input is connected with the output of the setting power mechanism, the first input of the summator and input of the magnifier, the output of which via the limit unit is connected with the input of the control switch, the output of which via the aperiodic filter is connected to the second input of the summator, the output of which is connected with the input of dead band unit.

EFFECT: upgraded efficiency of furnace and reduction of specific consumption of electric power.

3 dwg

FIELD: metallurgy, namely ore reducing furnaces, particularly improved operational reliability of self-firing electrodes at long time idling periods of furnaces for optimal setting of their operation mode.

SUBSTANCE: method comprises steps of controlling heat condition of bath of furnace; measuring nominal electric current of electrode, thermal e.m.f. of electrode-ground circuit; determining initial heating up current for further changing electric parameters according to desired program. In order to realize it, temperature of furnace bath inner wall is measured and temperature of electrode working surface at nominal electric current is detected. Initial heating up electric current is determined by means of mathematical expression.

EFFECT: improved technological and economical factors of ore furnace operation, enhanced strength of electrodes due to high reliability of estimation of their thermal state and providing optimal heating up mode of furnace after idling period.

1 dwg

FIELD: metallurgy.

SUBSTANCE: method for monitoring and controlling operation modes of scull vacuum electric arc furnace comprises steps of controlling voltage drop on arc and inter-electrode spacing; additionally creating in crucible volume sign-variable magnetic field whose intensity vector is directed normally relative to vector of electric arc discharge current; cyclically moving arc discharge along end of consumable electrode; monitoring electric arc discharge along end of electrode by means of program controlled video camera. Duration and intensity of pulses of sign-variable magnetic field is controlled by means of coils. Melt in crucible is agitated in horizontal and vertical planes due to interaction of coil magnetic field with electric currents spreading along scull.

EFFECT: improved explosion-proof properties of vacuum electric arc scull furnaces, enhanced uniformity of melt.

2 dwg

FIELD: metallurgy, special area of electric engineering concerning electrical arc heating during forging of various alloys, namely - automatic control over current power and position of electrodes of ore-thermal furnaces.

SUBSTANCE: method and system for automatic control are meant for controlling ore-thermal furnace, which has one three-phased or three one-phased furnace transformers, tub with liquid alloy being forged and stock, in which electrodes are positioned, connected by bus packets to low side of transformer. Automatic control system used for realization of method consists of voltage and current meters on the side of high transformer voltage; voltage meters on electrodes of magneto-sensitive elements, connected to current sensor, mounted on low voltage side (further in short network) of transformer. Chains of voltage and current meters on the side of high voltage are connected to first complex parameter meter of three-phased network, while chains of voltage meter and current indicator of short network are connected to second three-phased network parameter meter. Chains of first and second three-phased network parameter meters are connected to programmable logical controller.

EFFECT: increased efficiency.

2 cl, 5 dwg

FIELD: control systems for plasma reducing medium producing devices.

SUBSTANCE: proposed system has separate channels for feeding natural gas, atmospheric air, outlet gas, and water; each of mentioned channels incorporates series-connected control unit, flow regulator, and electronic flow sensor, as well as power supply regulator channel. Outputs of all channels are coupled with plasma generator; inputs of control units and outputs of electronic sensors are connected to computer; installed in gas producer output channel are temperature sensor and spectrometer, their outputs being connected to computer. Such arrangement provides for actually completely automatic process control and adherence to specified technology.

EFFECT: reduced power requirement, enhanced environmental friendliness.

1 cl, 1 dwg

FIELD: technology for adjusting power by phases of three-phased alternating-current electric arc-furnace, related to electric metallurgy and methods for power adjustment in three-electrode alternating-current arc furnaces.

SUBSTANCE: method includes adjusting power by phases by means of changing reactive component of resistance due to enabling of static capacitors battery in parallel to phase of short circuit, capacity of which is determined from electric formula where C - required capacity value of adjusting device, farads; ΔI - difference between active value of short circuit phase current with the least reactive resistance and active current values in one of two other phases, kA; D - area of liquid tub in calm state, m2; E - total area of cross-section of three electrodes, m2; P - nominal power of furnace transformer, Wt; n - mass of liquid component in metallic charging, kg; N - total mass of metallic charging, kg; k - coefficient, considering particularities of physical-chemical processes during melting in electric furnace and equal to (0,1-1,5)·10-11, c·A/Wt2.

EFFECT: increased productiveness of furnaces with decreased specific flow of electric energy.

1 dwg, 1 tbl

FIELD: electric engineering, in particular, electric metallurgy and methods for adjusting power in three-electrode alternating-current arc furnaces.

SUBSTANCE: during movement of electrode of one of three phases in working space of arc furnace to achieve symmetric mode of operation, reactive component of short circuit resistance is adjusted by changing capacities of capacitors batteries, connected in parallel to two other phases of short circuit. Capacity of batteries is selected on basis of empiric relation.

EFFECT: increased productiveness and decreased specific loss of electric energy.

1 tbl

FIELD: metallurgy.

SUBSTANCE: device for control of white alumina melting in electroarc furnace contains electrostatic precipitator implemented with ability of extraction of constant component of furnace voltage, comparator unit, current probe in electrodes. Device is outfitted by two summator, sensor of stages switching of voltage of transformer and microprocessor, herewith on inlets of the first summator there are connected electrostatic precipitator, current sensor in electrodes and sensor of switching of voltage stages of transformer voltage. Outlet of the first summator is connected to the first inlet of comparator, the second inlet of which is connected to microprocessor and outlets-to movement mechanism of electrodes and mechanism of stages switching of transformer voltage, outlets of the second summator are connected to current sensor in electrodes and sensor of stages switching of transformer voltage, and its outlet is connected to metering device of charge.

EFFECT: improvement of quality of received product.

1 dwg

FIELD: electrometallurgy.

SUBSTANCE: method consists in the control of reactive power of two and more arc furnaces by means of its sequential start into simultaneous operation, at that distance of proposed priority is defined by means of formula and depends on melt average duration, melting average duration, finishing average duration, average deviation of melting process, average duration of furnace downtime.

EFFECT: productivity improvement and decreasing of electricity specific consumption, reduction of negative impact of furnaces group to supply mains.

1 dwg, 1 ex, 1 tbl

FIELD: metallurgy of non-ferrous metals.

SUBSTANCE: invention is related to the electric metallurgy and may be used to control the vacuum arc fusion of the high reactivity metals - such as, for instance, titanium. In the method and quality of the technological parameter, an area of a visible section of the liquid metal bath must be chosen. This is then fixed with an optical transducer unit containing an optical axis that runs in parallel to the furnace axis and is located between an internal surface of the casting mold and an outside surface of an electrode being spent. This must be compared with its estimated value expressed as the single-valued function from an argument of displacement of the electrode axes with regard to the furnace axes in two mutually perpendicular directions, and the length of the electrode spent. The safety of an entire fusion process can be thereupon evaluated with the measured and estimated values of the visible image area of the liquid metal bath section that must coincide with each other. The following steps need to be taken to rectify and eliminate any production accidents: to shift the argument values of displacement of the electrode axes more than the threshold values, whereas the electrode's length must be shifted less than the said threshold value. Use of this invention allows to avoid any accidents that could otherwise occur when one performs a process of melting high reactivity metals and alloys. When this is implemented, it shall be possible to nip in the bud any initial moments when the aforementioned accidents may come into play, owning to a range of various technical reasons, e.g. fusion of an electric holder or an alignment error found in the electrode. The invention will preclude appearances of any faulty goods which could happen when, for example, an ingot is fused or when there are any discrepancies discovered in the operation of the furnace.

EFFECT: accident prevention and eradication of any potential faults which might occur when the melting process is conducted.

2 cl, 2 dwg, 1 ex

FIELD: metallurgy, namely ore reducing furnaces, particularly improved operational reliability of self-firing electrodes at long time idling periods of furnaces for optimal setting of their operation mode.

SUBSTANCE: method comprises steps of controlling heat condition of bath of furnace; measuring nominal electric current of electrode, thermal e.m.f. of electrode-ground circuit; determining initial heating up current for further changing electric parameters according to desired program. In order to realize it, temperature of furnace bath inner wall is measured and temperature of electrode working surface at nominal electric current is detected. Initial heating up electric current is determined by means of mathematical expression.

EFFECT: improved technological and economical factors of ore furnace operation, enhanced strength of electrodes due to high reliability of estimation of their thermal state and providing optimal heating up mode of furnace after idling period.

1 dwg

FIELD: processes and equipment for vacuum electric arc melting of highly reactive metals, namely large size ingot mold of crystallizer of vacuum electric arc furnace.

SUBSTANCE: ingot mold of crystallizer of vacuum electric arc furnace is monitored due to receiving objective data concerning its admissible wear degree. Ingot mold is monitored due to scanning magnetic field outside outer cylindrical surface of ingot mold at passing short -circuit electric current in system electrode-ingot mold.

EFFECT: explosion-proof process of refining metallic ingot, increased useful life period of ingot mold of crystallizer due to reading objective data related to wear degree of mold.

2 cl, 1 dwg

FIELD: metallurgy.

SUBSTANCE: method of controlling technology of electric-arc reduction smelting has adjustment of charge, electric and electrode modes due to periodical change in excess or deficiency of carbon in charge, switch of steps of voltage, and electrode switch and transfer. Electric parameters of state of phases and areas of working space of charge, arc and melt are determined as well as deviation of the parameters from preset ones for current moment of reduction cycle. Charge, electric and electrode modes are adjusted accordingly to found deviation.

EFFECT: improved productivity of furnace; reduced energy consumption.

The invention relates to metallurgy

The invention relates to a color electrometallurgy and can be used to control vacuum arc melting highly reactive metals and alloys, such as titanium

The invention relates to metallurgy and can be used in vacuum arc melting highly reactive metals and alloys

The invention relates to a special electrical engineering and can be used for process control vacuum arc melting highly reactive metals and alloys, such as titanium

FIELD: metallurgy.

SUBSTANCE: method involves consumable electrode manufacturing by shaping and compression of charge containing rutile, aluminium grit and fluidised glass as binding agent in a steel shell, and further feed of compressed consumable electrode by lifting device to fixation unit on horizontal bar of vertical stand of electric arc plant. Before feed to the said fixation unit, compressed consumable electrode is dried in drying chamber to dehydratise it. Before the end of consumable electrode drying, flux is loaded and melted into fluid state in crystallising tank by inconsumable graphite electrode mounted on additional horizontal bar of vertical stand. Further the inconsumable graphite electrode is retracted from the crystallising tank, and electric arc is excited between consumable electrode and lower eklectrode of crystallising tank under protective slag layer made of fluidised flux. Lime for melting in slag cover is fed to crystallising tank continuously.

EFFECT: improved quality of consumable electrode, obtainment of ferrotitanium ingot with improved titanium content, automated process of consumable electrode preparation and fusion.

13 cl, 1 ex

Up!