SU1423313A1 - All-purpose power source for arc welding - Google Patents

Abstract

This invention relates to a welding technique and is intended for arc welding with a melting and non-melting electrode. The goal is to expand technological capabilities. The device contains a controlled energy converter, current and voltage sensors with adjustable transmission coefficients. The control signal generating unit contains the first and second transfer coefficient control nodes, a switch with two inputs and two outputs, and an adder-amplifier with four inputs. The control signal conditioning unit allows you to smoothly or stepwise rotate the external voltage-current characteristic by up to ± 90 relative to its initial position. The device allows to obtain various universal characteristics of the power source by turning it relative to a preselected point. 1 h, p. f-ly, 3 ill. with (L

Description

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to

WITH

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This invention relates to a welding technique and is intended for arc welding with a fusible or non-consumable electrode.

The aim of the invention is the expansion of the technological capabilities of the equipment and the improvement of the quality of the welded joints due to the preliminary installation before welding.

about p

any (negative o i- -5-- 8Un

E1

zero

ei „

31

 Oh or positive

a) tilt output static91

This current-voltage characteristic of the power source of the electric arc, as well as the adjustment of the welding process by smooth or abrupt rotation of this characteristic by up to ± 90 relative to its initial position.

Fig. 1 shows a functional diagram of the proposed universal power source for arc welding; Fig 2 - external static. current-voltage characteristics of the power supply; in fig. 3 is a control circuit from a computer.

The universal power source for arc welding contains a controlled energy converter 1, current sensors 2 and voltage 3, output terminals 4, control signal generation unit 5, error amplifier 6 with three inputs 7, 8 and 9, setpoint 10, unit 11 maximum current limits, diodes 12 and} 3, the same terminals of which are connected to the input

the control signal generating unit 5 and one output each - to the outputs of the error amplifier 6 and the maximum current limit unit 11, while the output of the controlled energy converter 1 and the current sensor 2 input

connected in series and connected to the output terminals 4e in parallel with which the input of the voltage sensor 3, the outputs of the setting device 10, the current sensors 2 and the voltage 3 are connected respectively to the first Y, second 8 and third 9 inputs of the error amplifier 6, the output of the control shaping unit 5 The signal is connected to the control input of the controlled energy converter 1, and the input of the maximum current limit unit 11 is connected to the output of the current sensor 2.

Q

five

0

five

p

0

five

0 5

In addition, the error amplifier contains the first 14 and second 15 control ratios for the transfer coefficients, the switch 16 with two inputs and two outputs, cct 1-amplifier 17 with four inputs, the input of the first transmission coefficient adjusting node 14 is the first 7, and the inputs of the switch 16 - the second 8 and third 9 inputs of the error amplifier 6, the output of which is the output of the adder-amplifier 17, One output of the switch 16 is connected to the input of the second transmission-ratio control unit 15, and the other output is from The input of the adder amplifier 17, the remaining inputs of which are connected one at a time to the input of the first 14 and the outputs of the first 14 and second 15 nodes for adjusting the transfer coefficients, the adjustment nodes 14 and 15 being made with the same values of the transfer coefficients. The output signal of the setting device 10 is opposite in polarity to the output signals of the current sensors 2 and voltage 3,

The potentiometer that controls the voltage gain of the setpoint device is connected by point 18 to the input of the amplifier, the adjustable voltage is removed from point 19, and point 20 is connected to the zero power bus.

The potentiometer in block 15 is connected to the input of the amplifier by point 15, the adjustable voltage is removed from point 22, and point 23 is connected to the zero power supply bus.

The external static current-voltage characteristics of the source in Fig. 2 are shown with a section of natural characteristic 24, with a maximum current limit of 25. The family of characteristics when welding with a tungsten electrode in inert gases of a low-amp arc (switch 16 in the position shown in Fig. 1) contains g characteristic 26 for the transmission coefficient of the signals of the first and second control unit, which is within the range O - K il / varnish characteristic 27 for K 0 | 28 - / Ki, oh.

The family of characteristics at welding with a shchim electrode in protective gases (switch 16 in the opposite position, shown in FIG. 1) contains 142

life: characteristic 29 for 0 K- | K | :

characteristic 30 for K 0; the characteristic is 31 dL - | K | „d K 0.

The device works as follows.

Managed transducer 1 power. This translates the energy of the network into a welding voltage and a current supplying an electric arc, the magnitudes of which depend on the control signal supplied from the control signal generating unit 5 to the control input of the energy converter 1.

The input of the control signal generating unit 5 from the output of the error amplifier 6 is supplied with the signal of the difference between the corrected signal of the sensor 10 and the complex current and voltage feedback signal.

The adjusted setpoint signal Uj is the sum of the actual output signal of the setter 10 with the same signal, but multiplied by the transmission coefficient K of the first control unit 14, which is adjustable from a negative value to an absolute value equal to it. -1 to +1. In this way,

and mU, + pk, from, (1)

where type is the scaling factors of summation, with m p / K, /;

| tg 1 "oka

K, |., „„ - the maximum absot / "QKC

lute value of the coefficient K.

The complex feedback signal for current and voltage Uoj, depending on the position of switch 16, is defined as the sum of the signal UQCT from the output of current sensor 2 with the signal Ujj (, n from the output of voltage sensor 3 multiplied by the transfer coefficient K of the second control node which is structurally made similarly to the first one and is controlled simultaneously with it within the same limits. With the position of the switch 16 shown in Fig. 1, the complex feedback signal is

UOCK lUocT - K, and ",".

(2)

When switching the switch 16. B other position

 +

(3)

The difference between the complex feedback signal and the adjusted setpoint signal is generated in the adder-amplifier 17 due to the fact that the output signal of the setter 10 is opposite in polarity to the output signals of the current sensors 2 and voltage 3.

The power supply contains an automatic control system that tends to reduce the mismatch to zero, and the expression

Uj and „,.

(four)

Then at the position of the switch shown in FIG.

mU3 + nK, U.j mU ,,, + K, Kj. (5)

After conversion we have

/ KJ VlQUC K

 „

and to

/ kg

and "v. (6)

When switching the switch to another position

/ Kgschaks K

/TO/

("Ax

ost

(7)

The production of termwise multiplication of expressions (6) and (7) by the transfer coefficient oi. The connecting value, the increments of the output voltage of the power source and the magnitude of the voltage gain of the feedback signal for voltage, as well as the transfer coefficient and, coupling, the magnitude of the welding current increment of the power source I and the voltage increment of the feedback signal over current, we will obtain an increase in the output static characteristic of the power supply at the position of the switch 16 shown in FIG. one,

0 G / Ziz (1kix + K) - / K / mox1 | 5 LK

and

(eight)

0

After switching switch 16 to another position

tt "G N / K / moks + K) - KI

and | a

ABOUT

(9)

five

PL K (, kc

The graphical solution of equations (8) and (9) with respect to U and I is right in the coordinates of U and .1, With unchanged parameters oi, / and U and varying the value of the coefficient K in the range of (- / K /, oKc "after

5142.33

switching the switch 16 from to (,. the line will rotate by 180 around the point with coordinates I and and 0 Ujs gfichem obtained in the real power source and the static code will be limited to the verification by the so-called natural characteristic, i.e., output the characteristic -JQ of the given source, without feedback, on the right is the characteristic, which is formed by the maximum current limit unit 11.

In addition to the Toroj regulator; green: the signal level of the generator Uj, it is possible to carry out a parallel transfer of the characteristic, and to change the transfer coefficients oi and p 3 to set before welding and to change the coordinates during welding

of the center of rotation of the characteristic However, it should be noted that changing the coefficient p is necessary in order to maintain the same maximum current, 5 permissible current 5, to adjust the block 1 1 "If this is not desirable for any reason, then the input of the maximum current limit must be connected to -, the output of the current sensor (not shown) for which the coefficient p remains unchanged.

In some cases, it is advisable to use a simplified version of the power source for arc welding; in which there is no first node regulating the transfer coefficient. In this case, the error signal is the difference of the complex feedback signal from the actual signal of the setter. At the same time centers vrash, e nor. Characteristics; will lie at points with coordinates U О ,, I at the position of the switch. 165 shown in FIG. 15 or and -; i Ug .- I-O with a different switch position To, the output current-voltage static characteristics of such a source will be described by formulas;

()

(ten

Management of the characteristics of the proposed source of the punk: it is advisable to carry out automatically in accordance with a given program.,

Jq

j-

20

. ,,

 -

0

136

on commands from a computer, especially when welding by a robot.

When the universal power source is turned on, before initiating the arc, adjusting blocks 2, 3, 10, 14, 15, and 16 sets the output characteristic that is optimal for energizing the arc. Excite an arc with an oscillator (not shown) or short-circuit the electrodes. After excitation of the arc5, manually or automatically, according to signals from a computer, the output characteristic of the source necessary for the particular technological process is established.

For example, when welding with a melting electrode, after initiating the arc, a falling voltamper characteristic of the power source s is established, and when the arc voltage drops below a certain level, the transition from the falling characteristic to the declining one is automatically performed, which eliminates freezing of the electrode. Another characteristic, optimal for the end of the process, naprgtere when welding by robots - to increasing,.

A universal power source for arc welding, can be made for both DC and pulsed or alternating current welding.

The source allows smoothly or stepwise setting the required coefficient of the slope of the characteristic increasing, falling to compensate for disturbances or along the length of the arc, or due to the uneven heat removal during welding of thin-sheet structures. Y5 increase the stability of the system for automatically controlling the output parameters of the source; create an adjustable positive Nak-Pson static current-voltage characteristics of the arc power source during welding with a melting electrode for effective self-regulation of the welding process or to eliminate a crystallized metal drop at the end of the welding cycle; .1: and at the end of the welding electrode,

F o rmu l invention

Claims (1)

1 o Universal power source dp arc welding (content controlled energy converter, current and voltage sensors, master, error amplifier and control signal generating unit, characterized in that, in order to expand technological capabilities, it additionally introduces a switch, containing two inputs and two outputs, an adder-amplifier with Q four inputs and one output, the error amplifier being made containing the first and second nodes with adjustable transfer coefficients, the second and second inputs of the switch are connected respectively to the current and voltage sensors, the inputs of the adder amplifier are connected respectively to the first of the switch outputs, the output of the setpoint generator, and the outputs of the first and second nodes of the error amplifier, whose inputs are connected respectively to the output of the setpoint generator and the second output of the switch , the output of the adder-amplifier is connected to the input of the control signal generating unit, and the nodes of the error amplifier are made with the same absolute and adjustable at values of the transfer coefficients. 2, power supply according to claim 1, characterized in that the current and voltage sensors are made with adjustable transfer coefficients. .g - g: / Uj -dgUj f i atfUj M XU U "at K5, G6U7 | TP / 2 and. my ,thirty . :} f ffUss: Jasp. Ctvm code