SU408729A1 - DEVICE FOR AUTOMATIC EXCITATION OF THE ARC WHEN ELECTRIC WELDING IS MELTING - Google Patents

Description

one

This invention relates to the field of automatic electric arc welding.

Devices are known for automatically initiating an arc during electric welding with a melting electrode, consisting of a welding current source, an electrode feed mechanism with an adjustable feed rate, a welding current sensor, and a control unit connected to the electrode feed mechanism and a welding current source.

The operation of the known devices is based on the fact that when the end of the electrode feeding at a constant speed comes in contact with the product, a command mechanism from the welding current sensor reverses the feed mechanism. When this occurs, the accelerated removal of the electrode from the product in the opposite direction, resulting in an arc. Next, the feeder again iodizes the electrode to the product at the rate of electrode melting in a steady state welding mode.

However, such devices are not sufficiently reliable in operation in some cases of welding, for example, in automatic welding with iodine flux with patient speeds of a single electrode of a melting electrode and patient electrode diameters. The reasons for the low reliability of the devices are due to the lack of electrical contact between the mounted electrode and the product due to oxides on the metal surface, the flux crust (frozen at the end of the electrode after the end of the previous welding) or the dry flux granule trapped between the electrode end and the product.

Another reason for the low reliability is frequent breaks in the electric arc with increasing speed of the reversing mechanism. For these reasons, manual (non-automatic) excitation is resorted to.

arc, for example, stripping the end of the electrode and the product, prior to their electrical shorting, and then tearing off the electrode with simultaneous switching on of the welding voltage.

All this does not allow to fully automate welding processes and reduces productivity.

The aim of the invention is to eliminate

these shortcomings.

This is achieved by the fact that the proposed device is additionally equipped with a vibrator, a key and an electrode feed speed switch, while the input of the vibrator is connected with the output of the control unit through the key; the current sensor output is connected to the control; it has a key input and an electrode feed speed switch input, and the electrode feed speed switch output is

the input of the feeder electrode.

In addition, if there is a vibrator on the welding machine for other needs (for example, to improve the formation and properties of the NSA, as well as increase the welding speed), this vibrator can be used to initiate the arc, if it is provided with a vibration frequency switch, whose input is connected to the output of the welding current sensor, and the output is connected to the input of the vibrator, while the output of the wired unit is connected to another input of the vibrator.

FIG. 1 schematically shows a device for automatically initiating an arc at electric welding with a melting electrode, a block diagram; in fig. 2 is a block diagram of a device for the case of using a vibrator sticking on a welding machine; in fig. 3-option scheme of the device.

The proposed device consists of a mechanism / supply of a melting electrode with an adjustable feed rate; welding current sensor 2; a control unit 5 connected to the electrode feeding mechanism 1 and the welding current source 4; vibrator 5 end of the electrode; key 6 and switch 7 of the electrode feed rate. The output of the vibrator is connected to the control unit via key 6. The output of current sensor 2 is connected to the control input of key 6 and to the input of switch 7, the output of which is connected to the input of mechanism 1.

A device whose block diagram is shown in FIG. 2 differs from that described above only in that, instead of key 6, it contains a non-switch 8 vibration frequency, the input of which is connected to the output of welding current sensor 2, and the output is connected to the input of vibrator 5, while the output of control unit 3 is connected to another input of vibrator .

On the electrical circuit of the device (see Fig. 3), the electrode feeding mechanism / is represented in the form of a direct current electric motor with independent excitation and feed rollers. The role of welding current sensor 2 is performed by a current transformer. The control unit 5 is represented as a contactor 9 and a control key 10.

The source 4 of the welding current is a welding transformer. Vibrator 5 from a direct current electric motor with independent excitation and an eccentric device acting on the end of the electrode through the guide channel. The key 6 is the current relay 11 with normally closed contacts. The role of the switch 7 of the speed of the electrode nodal is performed by two pairs of contacts 12 of the same current. 13 — melting electrode; 14 — detail. (The dotted line conventionally shows the position of the end of the melting electrode during its vibration).

If the device uses a vibrator that is already on the welding machine, then instead of the key 6, the vibration frequency switch 8 must be set, which is played by the current relay 11 together with the resistance 15.

In both cases, the electric motor of the electrode iodatching mechanism is powered via the rectifying bridge 16 from the transformer p.

The excitation of the welding arc using the proposed device (see Fig. 1) occurs as follows.

On command from the control unit, simultaneously with the welding current source, the vibrator 5 of the electrode end and the mechanism / nodaci of the electrode are turned on. An electrode is supplied to set the product to be welded at a reduced rate, corresponding to the electrode melting rate at the moment of initiation of the arc. When this occurs, the penetration of the electrode core through the flux layer jc to the product being welded, destruction of the crust at the end of the electrode, mutual cleaning of the end of the electrode and the product and their repeated intermittent contact, which promotes the initiation of the arc. When the welding current is detected, a signal appears at the output of sensor 2

current. This signal switches key 6 to the “closed” state, and the switch of the electrode feed rate to the high-speed state. The vibrator is turned off; the electrode is fed at a rate corresponding to the nominal mode of welding.

The operation of the device shown in FIG. 2 differs only in that when the current in the welding circuit is detected, the signal at the output of the welding current sensor 2 transfers the vibrator 5, using the vibration frequency switch 8, from the higher vibration frequency required to initiate the arc, to the frequency corresponding to the nominal mode welding.

The operation of the device is based on a change in the voltage on the core of the electric motors supplying the electrode and the vibrator using the relay 11 welding current.

Subject invention

Device for automatic excitation of the arc during electric welding with a melting electrode, consisting of a source of welding current, an electrode feed mechanism

Adjustable iodine speed, welding current sensor and control unit associated with the electrode nodache mechanism and welding current source, characterized in that, in order to eliminate manual electrode and product cleaning and increase the reliability of automatic arc excitation, the device is equipped with a vibrator, key and switch the electrode feed rate, while the vibrator input is connected to the output of the key control unit, the current sensor output is connected to the key input and to the input of the speed switch to the electrode, and the output of the non-speed switch electrode nodachi - with the input of the feeder

electrode.

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