SU1480992A1 - Arrangement for igniting arc between nonconsumable electrode and article - Google Patents

Abstract

The invention relates to power transducer devices that power consumers with an arc load, and can be used in mechanical engineering and shipbuilding, where plasma torches are used. The purpose of the invention is to improve the dynamic characteristics of the plasma arc, as well as energy and weight and size parameters. The device contains a power transformer, the primary winding of which is connected to the mains through counter-connected thyristor pairs, and the secondary winding is connected via an uncontrolled rectifier containing a current sensor and a smoothing choke in the output circuit to the electrodes of the plasma torch. An oscillator is connected to the cathode and the burner nozzle. The device also contains an RC charging circuit and analog switches (AK). The middle point of the charging circuit is connected to one of the inputs of the comparison device. Its other input is connected to the output of the current sensor, and the output is connected through the AK to the phase shift unit. AK is also connected between the phase shift lock device and the phase shift block. The control inputs of all AKs are connected to the outputs of the control unit, the inputs of which are connected to the current sensor and the midpoint of the charging circuit. Information about the current of the plasma arc and the voltage on the capacitor of the charging circuit is fed to the input of the control unit, which, according to a predetermined algorithm, controls the AC, changing the topology of the entire control system of the device so that a smooth ignition of the plasma arc is achieved and stabilized. 1 il.

Description

The invention relates to devices for welding with a non-consumable electrode and can be used for automatic welding of various structures in transport engineering and other sectors of the national economy.

The purpose of the invention is to improve the quality of the welded joint by eliminating contamination of the weld metal and electrode.

The drawing shows a block diagram of the device.

The device for initiating the arc comprises a burner 1 with non-melting electrode 2 and filler wire 3 placed therein, article 4,. the first 5 and second 6 current sources, the first outputs of which are connected to

product 4. The second output of the first source 5, the current is connected to the non-consumable electrode 2, and the second output of the second current source 6 is connected to the input of the power switch 7, the control input of which is connected to the third output of the first current source 5 through the first sensor 8 power switch 7 through the current lead 9 is connected to the filler wire 3, the Third output of the second current source 6 through the second sensor 10 current is connected to the second input of the drive 11 of the filler wire 3, the first input of which is connected to the inputs of the first 5 and 6 second current sources. The current lead 9 is insulated relative to the welding torch 1 by means of an insulating sleeve 12.

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Sources 5 and 6 are power sources of an arc with a steeply dipping characteristic, for example, type VSVU, Sensors 8 and 10, the presence of current - relay circuits that react to a change in voltage at the output of the current source from idle to working (in VSVU-315) the standard arc relay). Drive supply 11 Filler wire - reversing drive of any type. Welding torch 1 secures the non-melting electrode 2, isolates the filler wire 3 and protects the weld zone.

The device for exciting the arc works as follows.

After supplying the protective gas to the welding torch 1 by the Start command, acting on the inputs of the current sources 5 and 6 and the first input of the filler wire supply drive 11, the said sources 5 and 6 of the current are turned on. Non-consumable electrode 2 is at a given distance 1 from surface of the product 4. The end of the filler wire 3 can be at an arbitrary distance from the surface of the product 4 At this initial moment of the current flow circuit from both sources 5 and 6 of the current is open. At the second outputs of sources 5 and 6 of the current there are signals about the presence of voltage at idle. The first current presence sensor 8 opens the power switch 7 with a signal, and the second current presence sensor 10 turns on the drive 11.

When the filler wire touches the surface of the product 4 through the metal contact bridges formed at the contact, the second current source 6 is closed — the power switch 7 — the filler wire 3 — product 4, through which the current flows, heating the contact bridges. The voltage at the output of the second current source 6 decreases to working, as a result of which the signal at the output of the second sensor 10 current presence changes to the opposite. The filler wire supply drive 11 switches to reverse and the filler wire 3 breaks off from the product 4. contact metal bridges that arise when touched

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filler wire 3 products 40 As a result, the auxiliary arc is excited, which burns between the filler wire 3 and product 4. Under the action of the high temperature of the auxiliary arc, the protective gas of the arc gap between the product 4 and the non-melting electrode 2, which is in the peripheral zone, is ionized action auxiliary arc. Electrode 2 warms up and a main arc arises between product 4 and non-consumable electrode 2 o. The signal from the output of the first current sensor 8 closes the power switch 7 and the supply circuit of the filler wire 3 breaks. The arc turns off, the voltage increases at the output of the second current source 6. up to the value of the no-load level, as a result of which the signal from the output of the second sensor 10 in the presence of current switches the actuator 11 to feed the wire 3 to the welding zone. The device switches to the welding mode of operation. If, after the filler wire 3 is cut off from the surface of the product 4, the main arc is not ignited, the auxiliary arc is stretched to a natural break, after which the filler wire 3 is re-supplied to the surface of the product 4. The supply voltage of the second source 6 is selected so that the end the filler wire 3 did not melt during the burning of the auxiliary arc, thus preventing metal spraying of the wire when the arc is excited and contaminating the tungsten electrode with it. The described cycle can be repeated many times on the drive of the main arch.

When the arc is repeatedly excited, there are no splashes and splashes of the main and filler metal, the seam has a shiny surface, and the seam metal does not contain intermetallic inclusions,

Claims (1)

Invention Formula A device for initiating an arc between a non-consumable electrode and a product, containing a current source connected to a non-consumable electrode and product, as well as an actuator for feeding an attachment wire, the first input of which is connected to the input source current, characterized in that, in order to improve the quality of the welded joint by eliminating contamination of the weld and electrode, it further comprises a second current source, two current presence sensors and a power switch, the first output of the second current source connected to the product, second exit through power the key is with the filler wire, the third output through the first current presence sensor is with the second input of the filler wire feed drive, the third output of the first current source, the second current presence sensor is connected to the control input of the power switch, and the current source inputs are interconnected.