SU727365A1 - Method of automatic electric-arc welding by modulated-current penetrated arc - Google Patents

Description

I

The invention relates to the field of welding and can be used for submerged free or compressed arc welding, both with controlled penetration depth and through penetration.

A known method of automatic electric arc welding with adjustable welding, which is carried out by measuring the temperature of the sliding pad and influencing the welding parameters 1.

The disadvantage of this method is that it requires cumbersome mechanical devices to move the sliding lining, and it also has a large inertia in transmitting the signal from the welding zone to the actuator. This is due to the inertia of the process of heat distribution in a sliding lining.

A known method of automatic pulse welding with a non-melting electrode in a protective gas with penetration through which uses an optical sensor that records the intensity of the light emitted by the root surface of the schv. The signal generated by the optical sensor interrupts the pulse of the welding current 2.

However, this method requires for the implementation of cumbersome mechanical systems necessary for moving and sighting an optical sensor, as well as its indication

Essentially zasi: ft from tё yrrepatypii.

Of the known methods of automatic arc welding, a submerged arc modulated current closest to the invention according to the technological essence and the achieved result is a method with automatic adjustment of penetration by varying the pulse duration of the welding current 3.

The method allows to interrupt the welding pulse, the current at the time of through-melting, or with a certain delay.

from the moment of receiving the signal about through penetration. The signal about the presence of through-melting is obtained using a photo sensor located on the back side of the welded part, which

reacts to the luminous flux of the plasma.

The disadvantage of this method is limited use, as in many welded structures it is difficult or impossible to access the reverse side of the seam at all (for example, pipes, box girders, etc.); and also complex control systems: to implement the method, cumbersome mechanical systems are required to install and move the photosensor, which significantly complicates the technological preparation of the method. The purpose of the invention is to precisely meter the energy used for penetration, and to simplify the method and equipment for its implementation. This is achieved by the fact that in the proposed method, the moment of current pulse disconnection is measured by comparing the voltage across the arc in the current pulse interval with the reference voltage. FIG. Figure 1 shows the voltage and current plots; in fig. 2 shows the functional scheme of the device; DZG | ShY11izy method. Power supply of an osuTs1ystbl yT modulated current. In this case, the pulse current / c, the pause current / n and the pause duration tr are set by the program, and the pulse duration is tu. during welding Change depending on the immersion of the arc in the metal being welded 16 while the current flowing impultea: The immersion of the arc in the metal depends on the arc pressure, which is proportional to the square of the welding current, and the flow time of the impulse current (J (. Under the action of the arc pressure melt; The molten metal is displaced from the crater, and the arc is immersed in the metal. With increasing arc immersion, the arc length component of the arc length increases in the metal being welded. This leads to an increase in arc voltage C. The arc arc voltage is compared with When the voltage of the arc of the reference voltage Uo is reached or with a certain delay, the impulse current is turned off. During the pause, the crater becomes depleted and the weight of the molten metal decreases. The initial arc length is equal to the open pilot, and, the next is sufficient, and the initial voltage on the arc is established. During the pause, the weld pool crystallizes. After a pause, the current is switched on, and the process is passed. The reference voltage Uo T ort is determined by the arc voltage Ug., At. which disable the pulse of the welding current. This voltage corresponds to a certain depth of immersion of the arc in the metal, and therefore, to a certain depth of penetration. By setting the reference voltage UQ to the voltage of the arc U at the time of the breakthrough of the plasma with the reverse strobe beam, the pulse current will turn off at the time of through-melting. The delay and switching off of the current of the pulse relative to the moment of receiving the signal about the presence of through-melting allows adjusting the width of the reverse side of the face. Example. Butt-weld plates of steel 12X18H9T with a thickness of 3 mm without butchering with automatic welding. Welding lead immersed arc. The arc is powered by a modulated current. The modulated current is obtained by introducing a ballast rheostat into the welding circuit. The pulse current / U, the pause current / n and the pause duration tn are programmed (350 A, 10 A, 4 s, respectively), and the pulse duration is changed depending on the arc immersed in the metal. The reference voltage is set to 15 V. The depth of the arc in the metal, and hence the depth of penetration, is contracted by the voltage on the arc Ug .. When the voltage on the arc reaches 15 V, the pulse current In turns on, the current of the pause In for 4 s. The bath is in equilibrium and crystallizes. The initial length of the arc is established, equal to the opening of the component, and, therefore, the initial voltage is established on the arc. After a pause, the impulse current is turned on and the process continues. In the welding circuit of the power source W with the supplying external characteristic, a ballast resistor 2 is included, which limits the current during a pause / c, which is shunted by a thyristor switch 3 during a pulse. Modulated current is obtained by switching the thyristor switch on and off. key 3. The signal to the thyristor key 3 from the comparator unit 4 through the amplifier 5 and the delay unit .6, turns off the pulse current / c. It stops the pause current In through a time equal to the duration of the activation of the current payzytn, the signal received in the block forming the duration of the pause 7, turns on the current pulse / c. The reference voltage is generated in the block forming the voltage of the voltage 8. Adjusting the pulse duration of welding ToK depending on the immersion of the arc allows you to get seams with a controlled penetration depth and, as a limiting case, with through penetration. The depth of penetration and the production of end-to-end penetration of fire are affected by the change in the welding process between the size of the gap between the parts to be welded, the blunting of edges and other disturbances, such as heat sink conditions at the beginning and end of the welding process. The use of the proposed method provides an accurate dosing of the energy used for penetration, the expansion of the technological possibilities of the application of the method and the simplification of its implementation in comparison with the known methods.

Claims (3)

1. Japanese Patent No. 46-9647, cl. 12 in 1. 2. US patent number 3702915, cl. 219-137, 1973. 3. Zh- “Welding production- :, 1975, No. 3, p. 19 - 20 (prototype). 727365 U2.2