RU2054346C1 - Welding apparatus - Google Patents

Abstract

FIELD: welding production. SUBSTANCE: apparatus includes the electric welding converter 1, the arc current relay 5, the setter 9 of arc turning-on signal; the pickup 10 of turned-on state of the switching device 2; the idle stroke voltage relay 16, the AND-gates 6, the OR-gates 7. EFFECT: increased degree of safety upon error operations of the arc current relay. 2 cl, 1 dwg

Description

 The invention relates to welding production and is aimed at improving the safety of welders, mainly in electric arc and plasma welding and cutting.

 Known devices for switching on an electric welding transducer, for example a rectifier, an inverter or a matching transformer, which provide for automatic blocking of the arc supply when its current is reduced to a level below the working one.

 The aim of the invention is to increase the level of electrical safety with false included relay current arc.

 The drawing shows an electrical functional diagram of the device.

 The welding device comprises an electric welding transducer 1, a power switch 2 connected between the network leads 3 and the power transducer, which is connected by a power output to the arc-forming electrode 4. The signal output of the converter is connected to the arc current relay 5. There is also a logical element OR 7, to the first input of which 8 is connected the setter 9 of the arc enable signal.

 An additional sensor 10 for the switched-on state of the switch 2 is introduced into the device, for example, on the basis of signal contacts or a reed switch switched simultaneously with the power contactors of the switch, or based on an intermediate relay mounted on the power output of the switch. Thus, the sensor 10 with its input (mechanical, electrical or magnetic) is connected to the additionally introduced corresponding (mechanical, electrical or magnetic) output 11 of the power switch.

 The sensor 10 is connected with its output to the first input 12 of the element 6, connected by the second input 13 to the output of the relay 5 and the output to the second input 14 of the element 7, the output of which is connected to the control input 15 of the power switch 2.

 To the output of the Converter is connected to the relay 16 open circuit voltage, which has a threshold above the operating voltage of the arc, but not above the open circuit voltage. Relay 16 is connected by its inverse output to the third input 17 of element 6.

 As a converter 1, an inverter, a rectifier, or a power isolation transformer can be used. The switch 2 can be made on the contact-mechanical or semiconductor basis. The arc-forming electrode 4 can be performed, for example, for either an open or a plasma arc of alternating or direct current. The current relay 5 can be performed, for example, on the basis of a combination of a measuring shunt or current transformers with electronic threshold devices, or on the basis of a reed switch. Elements 6, 7, 9, 10, 16 can be performed on contact-mechanical or semiconductor devices. The setter 9 in the simplest case can present a button with a self-reset, and in automated devices a logical device with one or a group of control inputs.

 The operation of the device is as follows.

 By pressing a button or by means of an external signal, the setter 9 is turned on and generates an enable signal, which is supplied to input 8 and includes an element 7, which in turn turns on the switch 2 at the input 15. As a result, a supply voltage is supplied to converter 1, the converter provides arc switching on electrode 4 by supplying electric energy to it. When the arc current reaches the normalized level, the arc current sensor 5 is turned on.

 In addition, when the switch 2 is turned on, a signal appears at the output 11, which leads to the inclusion of the sensor 10. Thus, after ignition of the arc due to the supply of signals to the inputs 12 and 13, the element 6 is turned on and supplies a signal to the input 14 of the element 7. Next, the setter 9 is turned off , i.e. ceases to produce an enable signal, however, this does not turn off the element 7, since the signal continues to be supplied to its input 14. The arc can be turned off in one of the known ways, for example, by increasing its length above the critical one, reducing the voltage of the converter 1 when the switch 2 is turned off. In addition, the arc can be turned off if, for some external reason or intentionally, the arc current decreases so much that this will lead to the shutdown of relay 5, which in turn will turn off the elements 6 and 7 of switch 2. Switch 2 disconnects the power to converter 1, as a result the arc goes out. Thus, a voltage blocking on the electrode 4 occurs.

 With the additional activation of the relay 16, the operation is carried out in the same way, except that the element 6 is turned on only if signals are supplied not only to the inputs 12 and 13, but also to the input 17 with the relay 16, when the arc voltage is lower than the open circuit voltage .

 Let us now consider the operation of the device with a false alarm relay 5.

 After turning on the arc when it is faulty, for example, due to sticking of the contact of relay 5, element 6 at input 12 and, accordingly, element 7 will be turned off at least until the signal from master 9 is supplied. Thus, the absence of voltage on the electrode is guaranteed for the case under consideration 4 even with a faulty relay 5.

 However, if the arc can be turned off, it can or should be done by increasing its length above the critical one or by reducing the voltage of the converter lower than necessary for arcing, using relay 16. In this device, after the arc goes out due to a malfunction of relay 5 to both inputs 12 and 13 element 6 signals are given.

 However, due to this extinction of the arc, the voltage at the electrode 4 rises and becomes equal to the open circuit voltage, as a result of which the relay 16 is turned on and the signal disappears at the input 17, as a result, the elements 6 and 7 are sequentially turned off, and then the switch 2, which in turn acting on the sensor 10 additionally and at the input 12 blocks the element 6, due to which the voltage is completely blocked.

Claims (2)

 1. DEVICE FOR WELDING, comprising an electric welding transducer connected through a power switch to a network, an arc current relay connected to an output of an electric welding transducer, an OR element connected to an arc switching signal setter as the first input, and an And element, characterized in that, for the purpose of to increase electrical safety during false switching on of the arc current relay, a switch-on sensor for the switch-on state is introduced into it, the input connected to the output of the power switch, and the output to the first input of the And element, the second input of which of the arc current is connected to the relay, and the output - to the second input of the OR gate, whose output is connected to a control input of the power switch.  2. The device according to claim 1, characterized in that an open-circuit voltage relay is connected to it, connected to the third input of element I.