SU795817A1 - Apparatus for automatic control of welding-and-soldering process - Google Patents

Description

one

The invention relates to electric welding equipment, in particular to functional diagrams of automatic devices for resistance welding and can be used in mechanical engineering, instrument making and electronic equipment.

A known block diagram of a device for monitoring the melting stage of a welded-on conductor, in which the duration of the welding cycle is determined according to the melting point of the welded-on conductor or, depending on it, 1.

However, in the known device, setting the reference voltage at the melting point does not usually correspond to actual welding conditions, which limits the possibilities of using the device and reduces its performance.

It is also known a device with voltage stabilization at the electrodes and cut-off of the welding current when the metal is melted in the gap between the electrodes 2.

The drawback of the device is the need to stabilize the voltage on the electrodes, which complicates the design and reduces the quality of welding.

A device for automatic control of the welding-soldering process is known, in which the duration of the welding cycle is set depending on the melting point, which is determined with higher accuracy by differentiating the signal simulating a change in electrical resistance 3.

However, the known device provides a stable quality of welding only in those cases when the actual time of penetration is equal to that entered into the system or, at least, is within a predetermined interval. With possible unforeseen deviations from tolerances of mass, heat capacity, or solder composition, the required melting time can be outside the specified interval, which leads to connection defects. In addition, when switching to welding products with a different averaging penetration time, another appropriate penetration time must be entered into the system, which limits the scope of the system and its performance.

Claims (4)

The closest in technical essence to the proposed device for automatic control of the welding process, containing a welding transformer connected via a rectifier to welding electrodes, a welding time relay in the supply circuit of the welding transformer, a differentiating circuit, an electronic switch 4. However, the device has a low control accuracy. as a result, welding quality decreases due to repeated conversion of the measurement signal. The aim of the invention is to improve the quality of welding. The goal is achieved by inserting a wattmeter into the device, the inputs of which are connected to the welding electrodes and the output of the rectifier, and the output connected in parallel with the inputs of the differentiating circuit and electronic key, the trigger connected between the differentiating circuit and the electronic key, integrators connected to the electronic outputs key, comparator, the inputs of which are connected to the outputs of the integrators, and the output is connected to the input of the welding time relay, the output of the welding time relay is connected in parallel to the trigger input and the second int inputs Thegenerators The drawing shows the functional diagram of the device for automatic control of the welding-soldering process. The device contains a welding transformer 1, a rectifier 2, welding electrodes 3, a welding relay 4, a differentiating circuit 5, an electronic switch 6, a wattmer 7, a trigger 8, integrators 9 and 10, a comparator 11. The device operates as follows. From the welding transformer 1, the current through the rectifier 2, the wattmeter 7 is supplied to the welding electrodes 3. A signal removed from the wattmeter 7, proportional to the power applied to the electrodes, is fed in parallel to the differentiating circuit 5 and the electronic switch 6. In the initial state, the electronic switch passes the signal the first input of the integrator, 9 and further to the first input of the comparator II. At the same time, the same signal is fed to the input of differentiating circuit 5, the output of which is connected to the input of trigger 8. This circuit ensures the singling out of special points on the curve of the functional dependence of resistance on temperature, which records an abrupt change in the speed of the input signal at the moment of resistance jump during melting. The impulse, which fixes the beginning of melting, passes the differentiating circuit 5 flips trigger 8, which switches the output of the electrode key 6 to the input of the second integrator 10. From the outputs of the integrators, signals arrive at the inputs of the comparator 11, in which they are compared in a predetermined ratio the input of comparator 11 is transformed in a given ratio. When the signals are equal, the comparator outputs a signal to the welding relay 4, which, with its contacts, turns off the welding current, sets integrators 9 and 10 and trigger 8 to their initial position. Automatic control of the welding-soldering process is based on the fact that the relationship between energy E | The heating of the parts to be welded to the melting point of solder and the energy E that goes to the solder melt is determined only by the physical parameters of the materials being welded and does not depend on the change in the process parameters and the mass of the solder. E, ((T) dT, (1) where wn, rn is the mass of solder and parts to be welded, respectively; Cu, C are their specific heat capacities; Then is the initial temperature; TPA is the melting point of solder., (2) where q is the specific heat of fusion of the solder. From (1) and (2) it follows that E2 ai (Ei -ag), (3) "JTpd wherea, -t, - jT-jj--, aj. w / C (T) dl (4) j; d dTTo The physical meaning of expression (3) is that the heating energy of the solder from the initial temperature to the melting temperature is proportional to the energy required for complete melting and soldering, and the coefficients ai and a depend on the heat capacity of the solder andparts to be welded, the specific heat of fusion of solder and the mass of parts to be welded, which can be considered constant within a specific technological process.Thus, the proposed device allows to improve the quality of welding-soldering due to the fact that the control mode of welding-soldering welding within specified limits, which may vary in the welding cycle and do not require stabilization of one of the welding parameters, such as voltage across the electrodes. Apparatus of the invention for automatic control of the welding-brazing process, comprising a welding transformer connected via a rectifier to welding electrodes, a welding time relay in the supply circuit of the welding transformer, a differentiating circuit, an electronic switch, characterized in that The device has a wattmeter, the inputs of which are connected to the welding electrodes and the output of the rectifier, and the output is connected to the inputs of the differentiating circuit and an electronic key, a trigger connected between the differentiating circuit and the electronic key, integrators connected to the outputs of the electronic key, a comparator whose inputs are connected to the outputs of the integrators, and the output is connected to the input of the welding time relay, the output of the welding time relay is connected in parallel to the trigger input and second inputs of integrators. Sources of information taken into account during the examination 1. V. Atamanov, A. P. Isaev. The study of the welding process with a micro gap with automatic tracking of the melting stage. “Instruments and control systems, 1970, No. 6, p. 59. 2. Krasuln Yu. L. Nazarov G. V. Micro-welding by pressure. M., “Metallurgists, 1976, p. 139-141. 3. USSR author's certificate number 463524, cl. In 23 K 11/24, 1974. 4. USSR author's certificate number 519301, cl. In 23 K 11/24, 14.03.75.