SU795795A1 - Apparatus for regulating welding current - Google Patents

Description

(54) DEVICE FOR REGULATING WELDING CURRENT

one

The invention relates to welding equipment, and in particular to welding equipment.

A device for adjusting the ignition angle of power controlled valves in the power sources of the welding arc is known, comprising a phase-rotating circuit consisting of series-connected adjustable resistors and a capacitor and connected to the secondary winding of a power transformer having an average terminal. The magnitude of the welding current is determined by the position of the phase-shifting resistor, and the decrease in the value of the welding current during the crater welding process (shrinkage shell) is switched by the contacts shunting one or more resistors connected in series to the phase-changing circuit 1.

A disadvantage of the known phase-regulating devices is an abrupt reduction of the welding current, leading to the formation of a crater at the end of the weld, which is a welding defect and in all cases should be eliminated. At the same time, the presence of switching contacts reduces the reliability of the phase-adjustable device with an increase in the number of switched resistors and complicates the device to control them.

It is also known a device for adjusting the welding current, comprising a series-connected capacitor and a rectifying bridge connected to the secondary winding of a power transformer having an average terminal. The regulating element consists of a series-connected variable resistor and a transistor connected in accordance with a common emitter circuit, and a rectifier bridge connected to the diagonal. The base-emitter control circuit of the transistor is connected to an additional power source 2.

Claims (2)

The known device does not allow an automatic smooth crater welding mode, since the collector current of the transistor is nonlinear to the control current of the base $ 3 in a wide range of current of the UK collector, the nonlinearity of the current base j8 gain, and the nonlinearity of the input characteristic of the transistor, especially silicon, worsen the smoothness of the regulation of the welding current. The purpose of the invention is to improve the quality of the weld by smoothly reducing the welding current when the crater is welded. The goal is achieved by introducing an integrated amplifier into the device, the input of which is connected to an additional power source and the output to the emitter of a transistor connected according to a common base circuit, the base of the transistor being connected through a capacitor to the input of the integrating amplifier and the collector of the transistor with adjustable resistance. Switching on the transistor according to the common base scheme eliminates the influence of the nonlinear dependence of the base current transfer coefficient on the smoothness of welding current decrease due to the fact that the emitter current transfer ratio i 1 and 1e is 7k. The introduction of the base-emitter circuit of the transistor into the feedback loop circuit is integrated, its amplifier allows to eliminate the influence of the nonlinearity of the input characteristic of the transistor on the smoothness of the welding current decrease. The drawing shows a diagram of the device. The device contains a power transformer 1, a rectifying bridge 2, a transistor 3 connected according to a common base circuit, an adjustable resistance 4 connected to the collector of transistor 3, an integrated amplifier 5 with a capacitor 6 and a load resistance 7 of the integrating amplifier 5, the input of the integrating amplifier 5 is connected through the resistance 8 to the negative terminal 9 of the additional power supply, and through the contacts 10 to the positive terminal 11 of the additional power supply, the output of the device are the terminals 12. Trimmer resistor p 13 used for setting an initial angle of the power plug valves arc power source. The device works as follows. In the initial state, the contacts 10 are closed, and at the output of the integrating amplifier 5 the polarity of the voltage is negative as a result of the transistor 3 being open and in the saturation state. The variable resistor 4 engine through an open collector junction - the base of the transistor 3 is connected to the bottom of the variable resistor 4 according to the scheme, which corresponds to the welding mode. The contacts 10 are opened with the start of the crater brewing process, and the output voltage of the integrating amplifier 5 begins to increase linearly. The time of the crater welding process corresponds to the integration time and is set by the position of the variable resistor 8 engine. A linear increase in the voltage on the load 7 of the integrating amplifier 5 to a positive value causes a linear decrease in the current in the load circuit 7 flowing simultaneously through the emitter-base junction of transistor 3. Thus the control junction current of the transistor 3 is determined by the linearly increasing voltage across the load 7 and depends little on the nonlinearity of the emitter-base transition of the transistor, as a result of which The input characteristic of the transistor 3 is artificially linearized by the feedback circuit of the integrating amplifier 5. During the integration process, a smooth transition of the transistor 3 from the open state to the closed state occurs, which causes a smooth increase in the resistance of the variable resistor 4 to its maximum gates. The contacts 10 are closed again after breaking the welding arc circuit, and the circuit returns to the initial state. The proposed device can be used when welding any products, especially thin-walled stainless steels and titanium with a thickness of 0.5 mm and above. Apparatus of the invention for adjusting the welding current, comprising an electrically connected welding transformer, an additional power source, a transistor, a capacitor connected to the base of the transistor, and adjustable resistance, characterized in that, in order to improve the quality of the weld by smoothly reducing the welding current when crater welding, an integrating amplifier is introduced into the device, the input of which is connected to an additional power source, and the output is connected to the emitter of the transistor included in the circuit Ie with a common base, while the base of the transistor through a capacitor is connected to the input of the integrating amplifier, and the collector of the transistor is connected to an adjustable resistance. Sources of information taken into account in the examination 1.Power source IPID-ZOOM. Instructions for use. NIITekhnologii and organization of production NIAT, 1967. 2. Japanese Patent No. 48-13266, cl. In 23 K 11/24, 1973.