RU2110382C1 - Method for pumping lamp of solid-body radiator under pulse-periodic conditions and device for its embodiment - Google Patents

Abstract

FIELD: laser engineering, more specifically, laser treatment of metals. SUBSTANCE: method consists in lamp firing, arc initiation and voltage increase that results in rise of current flow through lamp up to occurrence of generation. After lamp firing positive half-cycles are supplied with frequency of 150-180 Hz, stationary arc is formed with current of 15-17 A, half-cycle duration is changed from 3.0 to 6.5 ms and pulse is formed with power determined by the offered mathematical relation. The device for embodiment of the offered method consists of successively connected transformer, three-phase rectifier and firing unit. Control unit and DC amplifier are successively connected to each other and to rectifier, and additional injection unit is parallel to rectifier. The device is additionally provided with shock-wave protection unit and high-voltage protection unit. Shock-wave protection unit is provided between rectifier and pumping lamp with series-parallel connection. High-voltage protection unit is arranged between rectifier and firing unit with series-parallel connection. Provision is also made of contactor switch installed between additional injection unit and rectifier. EFFECT: higher efficiency. 4 cl, 5 dwg, 1 tbl

Description

 The invention relates to laser technology, namely to metal processing by a laser beam.

 Known lasers of the "Quantum" series, having a pulsed pump source of lamps, which have found application in technological processes of welding, marking of metals and alloys [1].

 However, their use in the technology of cutting materials is difficult due to the low pulse repetition rate, and, as a result, the low average radiation power.

 LIT series lasers used in sheet metal cutting technology have a pulsed power supply for pump lamps [2].

 The disadvantages of the known laser are the introduction of electrical noise into the CNC units of the equipment combined with the laser, as well as the low electrical safety of the personnel from accidental breakdowns by electric current.

 The closest technical solution to the invention is a method of pumping a lamp of a solid-state emitter using the example of a power supply SPIK 1, in which the lamp is ignited by applying a high voltage short pulse of 25-30 kV, supplying a supply voltage of 1500 V to form a stable arc in the lamp, applying power supply to the lamp. With a change in the supply voltage to the lamp, the current passing through it changes, and with an increase in the pump current, generation appears at the output of the emitter [3].

 The disadvantages of the continuous method of pumping the lamp are the limited range of the continuous mode, since when processing materials, the boundary edges overheat and violate its structure, the tediousness of the selection of the technological mode of processing both by the pump current and by the nomenclature of materials. When using continuous radiation, it is not possible to increase the output radiation power, in order to increase the power, it is necessary to switch to other more powerful systems.

 The closest device of the same purpose to the claimed device in the group of inventions according to the totality of features is a device for pumping solid-state emitter lamps, consisting of a transformer, a three-phase rectifier and an ignition unit connected in series, while the control unit and the current amplifier are connected in series with each other and the rectifier and the make-up block parallel to the rectifier.

 A disadvantage of the known device is the presence of a capacitive filter consisting of a choke and a set of electrolytic capacitors, which must be maintained. Being inoperative for 10-15 days, before work, it is necessary to train the capacitors of the power system by charging and discharging with a gradual increase in voltage to working, and maintain at operating voltage for at least 30 minutes. In addition, the service life of capacitors is limited and their cost is high.

 EFFECT: improved technological characteristics of processing by increasing the radiation power density on the surface of the processed material.

где

оптимальная плотность мощности лазерного излучения;
η - коэффициент повышения КПД системы при переводе ее из непрерывного в импульсно-периодический режим = 1,1-1,12;
P_{ср.непр.} - средняя мощность непрерывного режима излучения;
n - длительность полуволны периода повторения импульсов, мс;
m - длительность импульса в период одной полуволны, мс.The specified single technical result in the implementation of the group of the invention is achieved by the fact that in the known method of pumping a lamp of a solid-state emitter in a pulse-periodic mode, which consists in igniting the lamp, forming an arc, increasing the voltage and, as a result, increasing the current through the lamp until generation occurs, the feature is that after the lamp is fired, positive half-waves are fed with a frequency of 150-180 Hz, they form a steadily burning arc with a current of 15-17 A, change the half-wave duration from 3.0 to 6.5 ms and form mpuls power determined from the relationship:

Where

optimal power density of laser radiation;
η is the coefficient of increase in the efficiency of the system when it is transferred from continuous to a pulse-periodic mode = 1.1-1.12;
P _cf. - the average power of the continuous radiation mode;
n is the half-wave duration of the pulse repetition period, ms;
m is the pulse duration in the period of one half-wave, ms.

 The task is also achieved by the fact that the device for pumping the lamp of a solid-state emitter in a pulse-periodic mode, consisting of a series-connected transformer, a three-phase rectifier and an ignition unit, while the control unit and the DC amplifier are connected in series with each other and the rectifier, and the makeup unit parallel to the rectifier, is additionally equipped with a shock wave protection unit and a high voltage protection unit, wherein the follower protection unit is connected but-parallel between the rectifier and the pump lamp, and the high voltage protection unit is connected in series-parallel between the rectifier and the ignition unit, while a contactor key is installed between the make-up unit and the rectifier. In addition, the shock protection block consists of a parallel resistor and a diode and a capacitor connected in series with them, and the high voltage protection block consists of a diode connected in series with the parallel capacitors.

 The inventive method and device allow to obtain fundamentally new opportunities for constructing the power characteristics of a laser beam with a higher efficiency of the entire system.

 In FIG. 1 shows a graph of the distribution of radiation power in a series of pulses; in FIG. 2 is a structural diagram of a device according to the 2nd claim; in FIG. 3 is a block diagram of a device according to the 3rd claim; in FIG. 4 is a block diagram of a device according to the 4th claim; in FIG. 5 is a circuit diagram of a device.

 The method of pumping a lamp solid-state emitter in a pulse-periodic mode is as follows.

 The pump lamp is ignited in three stages: at the first stage, high-voltage pulses with a voltage of 25-30 kV and a duration of 0.5-0.6 μs are formed, which, falling on the lamp, form an electric arc in its interelectrode gap. Since the lifetime of this arc is short - 0.2-0.5 μs, in the second stage, the power source for the standby arc with a voltage of 1500-1700 V comes into operation. In the third stage, the main power source is turned on, which pumps the lamp with positive half-waves using thyristors. By changing the opening angle of the thyristors in the rectifier, you can change the half-wavelength, which leads to a change in the current in the lamp and allows you to adjust the output radiation power.

The voltage on the lamp has a pulsating character with a voltage frequency in the network of 150-180 Hz. The current of the duty arc in the pulse-periodic mode is 15-17 A and is set individually for each lamp due to the initial opening angle of the thyristors. Regulation and stabilization of the output current in the rectifier is due to the feedback installed in the positive circuit. The feedback voltage taken to the non-inverting input 3 of the D1 chip from the shunt R _os feedback is set and applied to the inverting input 2 of the D2 chip. A non-inverting input 3 of the D2 chip is supplied with a stabilized reference voltage.

 The stabilization of the output current is as follows. Suppose that the output current of the system has increased, therefore, the feedback voltage from the shunt R, which is fed to input 3 of the D1 chip, has increased. The voltage at the output 6 of the microcircuit D1 increases, and the voltage mismatch at the output 6 of the microcircuit D2 decreases, which leads to an increase in the turn-on angle of the thyristors and a decrease in the output current of the system.

 The half-wave duration is established from the calculation: the minimum duration (3 ms) is selected based on the time required to create the conditions for the generation of radiation (with a smaller value of the minimum duration, the arc will go out), the maximum duration (6.5 ms) is selected based on the energy characteristics of the lamp (at a longer lamp has a longer value).

 Since the lamp operates in a pulsed-periodic mode, the generation from the active element is pulsed, but in contrast to the lamps, the radiation pulse does not arise from a certain value, but from 0, therefore, with the same value of the average power, the peak power is higher by 2- 3 times. This allows you to reduce the time of exposure to the processed material, and as a result, the zone of thermal influence on the processed edge is reduced. This allows you to increase the thickness of the processed material and improve the quality of processing.

 From the graphs presented (Fig. 1), it can be seen that with the proposed pumping scheme of the lamps of a solid-state emitter with the same values of power consumption, it is possible to obtain a higher, 10-12%, output power of the generator compared to the continuous mode, and the proposed method of constructing a mode for following radiation pulses It does not affect the internal resonance processes (thermal lenses of active elements in the generator, the divergence of radiation and the resistance of optical elements).

Hence,
P _cf. = P _av ,
Where
P _cf. - the average power of the pulse-periodic radiation mode;
P _av - the average power of the continuous radiation mode;
η is the coefficient of increase in the efficiency of the system when it is transferred from continuous to a pulse-periodic mode = 1.1-1.12.

где
n - длительность полуволны периода повторения импульсов, мс;
m - длительность импульсов в период одной полуволны, мс.At f = 150 Hz, n = 6.6 ms, m = 2 ... 6.5 ms, I = 17-36 A, the power of a single pulse will take the form:

Where
n is the half-wave duration of the pulse repetition period, ms;
m - pulse duration in the period of one half-wave, ms.

 The proposed method is implemented in a device that consists of a series-connected transformer 1, a three-phase rectifier 2, consisting of diodes UD1 ... UD3 and thyristors UT1 ... UT3, an ignition unit 3 and connected in series with each other and a rectifier 2, a control unit 4 and a direct current amplifier (DCT) 5. The direct current amplifier is assembled on 2 integrated circuits - operational amplifiers D1 and D2 and is designed to amplify feedback voltage, set a given output current value, and also set power adjustment units. A shock wave protection unit 6, consisting of a resistor and a diode connected in parallel with each other and a capacitor in series with them, and a high voltage protection unit 7, consisting of a diode connected in series with the parallel connected capacitors, are installed on the device. In addition, the shock protection block is connected in series-parallel between the rectifier 2 and the pump lamp, and the high voltage protection block 7 is connected in series-parallel between the rectifier 2 and the ignition unit 3. A contactor key 9 is provided between the make-up block 8 and the rectifier 2.

 Working power source for the proposed method is as follows.

 Three-phase voltage with a frequency of 50 Hz is supplied to rectifier 2. From the control unit 4 at idle (without load), short pulses are sent to the thyristor control electrodes so that the thyristors are ajar and ready for operation. At the input of the source there is a voltage of ≈ 250 V.

 When the lamp is ignited, short high-voltage pulses are formed in the ignition unit 3, which, falling on the pump lamp, form an electric arc. At this time, the contactor K1 is turned on, which supplies an additional voltage (feed voltage) = 1500-1700 V. The power source starts to produce pulses from the rectifier with a frequency of 150-180 Hz supplied to the lamp.

 When the lamp is ignited, short high-voltage pulses (20-30 kV) are formed in the ignition unit, which can penetrate to the power supply elements, and lead to breakdown due to the large potential difference on the electrodes. In order to avoid this, a high-voltage protection unit 7 is introduced, which does not affect the quality of the output pulses (does not smooth them due to the low capacitance), but prevents the possibility of the passage of a short high-voltage pulse into the power section.

 At the initial time, the resistance of the formed arc is minimal, and the voltage at its electrodes corresponds to the idle speed of the source (max), which leads to a rapid increase in the passage of current through the lamp and the occurrence of a shock wave in it. In order to avoid the occurrence of a shock wave capable of incapacitating a lamp, a shock wave protection unit 6 is introduced into the negative circuit of the lamp.

 As a result of the tests carried out at f = 150 Hz and I = 17-36 A, comparative characteristics were obtained for processing steels 65 G and 40 X with a thickness of 4 mm in continuous and pulse-periodic modes (table).

Sources of information
1. Gerasev S. A., Gerasev O.A., Nikitin A.M., Opre V.M. Modern power systems for solid-state laser technological installations. - L., 1990.

 2. Golubev V.S., Lebedev F.V. Physical fundamentals of technological lasers. - M.: Higher School, 1987.

 The power supply system, testing and monitoring the operation of the SPIK-1 emitter. Passport URM 2.625.004 PS.

Claims (4)

1. The method of pumping lamps of a solid-state emitter in a pulse-periodic mode, which consists in igniting the lamp, forming an arc, increasing the voltage and, as a result, increasing the current through the lamp until generation occurs, characterized in that after the lamp is ignited, positive half-waves are supplied with a frequency of 150 - 180 Hz, they form a steadily burning arc with a current of 15 - 17 A, change the half-wave duration from 3.0 to 6.5 ms and form a pulse with a power of

where η = 1.1-1.12 is the coefficient of increase in the efficiency of the system when it is transferred from continuous to a pulse-periodic mode;
R _{with p . n e r n} - mean power continuous wave mode;
n is the half-wave duration of the pulse repetition period, ms;
m is the pulse duration in the period of one half-wave, ms.  2. A device for pumping a lamp of a solid-state emitter in a pulse-periodic mode, consisting of a series-connected transformer, a three-phase rectifier and an ignition unit, while the control unit and the DC amplifier are connected in series with each other and the rectifier, and the make-up unit is parallel to the rectifier, characterized in that the device is additionally equipped with a block of protection against a shock wave and a block of protection against high voltage, and the block of protection against a shock wave is connected in series in parallel about between the rectifier and the pump lamp, and the high voltage protection unit - sequentially in parallel between the rectifier and the ignition unit, while a contactor key is installed between the make-up unit and the rectifier.  3. The device according to claim 2, characterized in that the shock wave protection unit consists of a parallel-connected resistor and a diode and a capacitor connected in series with them.  4. The device according to claim 2, characterized in that the high voltage protection unit consists of a diode connected in series with parallel connected capacitors.

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