RU2131340C1 - Method of and circuit for control of operation of multiple-transformer welding machine - Google Patents

Abstract

FIELD: mechanical engineering; automotive industry; welding of units of any configuration with large number of welding spots. SUBSTANCE: all spots and electrodes with their drives on each station of multiple-transformer welding machine are divided into four groups. Welding time of one group of electrodes is set equal to electrode upsetting time of other group of electrodes, to time of shifting of electrodes of third group to welding place and to move-off of electrodes of fourth group. Computer provides counting of electrode pressure time before welding, and pressure application time after welding. Electrode pressure time before welding is set one for first spot in first cycle. Pressure application time after welding is set after welding of last spot in last cycle. Outputs of computer are connected with inputs of regulator counters, and outputs of counters, with inputs of computer. Welding cycle regulators have one welding current flow time counter. EFFECT: increased welding rate, reduced peak loads on supply circuit, reduced installed power of machine. 3 cl, 2 dwg

Description

 The invention relates to methods for controlling the operation of multi-transformer machines and automatic lines for contact electric welding and can be used in various industries, in particular in the automotive industry, when welding units of any configuration with a large number of welding points (over 30 points at one station).

 Known methods for controlling spot welding, circuits and devices of machines with sequential activation of welding transformers, containing power switching devices in the primary circuit, welding control units or welding current controllers (see, for example, AS N 774852, class B 23 K 11/24, 1980). The device provides for the sequential inclusion of welding machines in groups. The number of cars in the group depends on the supply voltage. In each group, welding is carried out according to the standard cycle - compression, welding, forging, expansion.

 The disadvantage of this control, in addition to peak loads on the power supply network, is the low productivity of welding machines as a result of repeating the complete welding cycle by each group of transformers.

 Closest to the proposed technical solution is the "Control system of the flow line of contact welding" by A. with. USSR N 946853, class B 23 K 11/24, 1982. It contains several autonomous control flows connected by conveying devices, welding current controllers, commutators. Each controller controls one welding machine in each welding cycle. The computer controlling the controllers includes several controllers simultaneously.

 The disadvantages of this control system are the following: the presence of peak loads, low productivity of welding machines, called the simultaneous switching on of machines in a group with a repeatability of the full welding cycle by each group, a small load factor of welding equipment due to the large number of thyristor contactors, welding transformers (welding machines), the presence of shunt currents caused by interphase voltage and voltage between the electrodes from the use of different modes when welding parts of different the ravines.

 The problem solved by the proposed technical solution is aimed at increasing the speed of welding points, reducing peak loads on the power supply network and reducing the installation capacity of the machine. This problem is solved as follows: all points and electrodes for welding these points at the post of a multi-transformer welding machine are divided into four groups, combine the welding time of the first group of electrodes with the compression time of the electrodes of the second group, with the time of movement of the electrodes of the third group to the welding site and with the time of expansion of the electrodes of the fourth group. The compression time of the electrodes is set once before welding the first point of the first group. The exposure time of the electrodes under pressure after welding is set only for the last point in the last group. Welding cycle controllers use one counter for the flow of welding current, and the computer performs the functions of counting the compression time of the electrodes before welding the first point in the first group and holding the electrodes under pressure after welding the last point in the last group.

 The circuit contains welding transformers, thyristor contactors, the control inputs of which are connected to the outputs of the regulators of welding cycles, and the outputs are connected to the welding transformers, a computer that sets the sequence of the regulators and the number of the welding mode, the regulators of the welding cycles having one counter for the duration of the welding current. The inputs of the counters of the regulators are connected to the outputs of the computer, and the outputs of the counters of the regulators are connected to the inputs of the computer.

 In connection with combining the welding operation with the operations of moving groups of electrodes, compression and their expansion, it became possible to perform continuous sequential welding at one point, the cycle time was reduced, the welding speed increased, the machine installed power and peak loads on the power supply network decreased.

 In the prototype, the following takes place: at the same time, several welding machines are switched on (up to 6), the compression time of the electrodes before welding and the exposure time of the electrodes under pressure after welding are set separately for each machine, each machine operates according to a standard sequence: compression, welding, forging, the expansion, the total cycle time of the machine (line) is reduced due to the simultaneous operation of welding machines in the group, increased installation power, a large number of welding machines (transformers, thyristor contactors).

 In FIG. 1 shows a sequence diagram explaining the essence of a method for controlling the operation of a multi-transformer welding machine; in FIG. 2 shows a diagram that implements the method.

 The control circuit of the operation of a multi-transformer welding machine consists of welding transformers, the primary windings of each of them are connected in series with thyristor contactors, the control inputs of which are connected to the outputs of the regulators of the welding cycles, which contain one counter for the duration of the welding current. The inputs of the counters of the regulators of the welding cycles are connected to the outputs of the computer, and the outputs of the counters are connected to the inputs of the computer.

 The computer sets the mode number and the sequence of operation of the regulators of welding cycles, counts the time of compression of the electrodes before welding the first point of the first group and the exposure time of the electrodes under pressure after welding the last point in the last group.

 The implementation of the method of controlling the operation of a multi-transformer welding machine using this scheme is as follows.

 At the beginning of the welding cycle, the computer according to the program issues a command to compress one pair of electrodes of the first group (v.4, v.9) from transformers TC1 and TC2 and simultaneously to move the electrodes of the third group to the welding site, sets the number of the welding mode RCS1 and RCS2 and starts counting the compression time of the electrodes before welding the first point. After counting the compression time of the electrodes T1, the computer issues a “start” command to the input of the welding cycle regulator - RCS1 to start it and a command to compress the electrodes of the second group (see Fig. 1). The RCS1 gives a signal to the thyristor contact TK1 for its inclusion, and the counter RCS1 starts the countdown of the duration of the flow of welding current Tsv. 1 according to the specified mode. The first point is welded (v. 4). The RCS1 regulator disconnects the thyristor contactor TK1 after counting the flow time of the welding current Tsv.1, from the output B of the controller RCS1 a signal is received at the input of the computer from the end of the operation of RCS1. The computer determines the order of start of the next RCS in the group, issues a “start” command to the input of the RCS counter. RCS2 similarly starts the thyristor contactor TK2 in operation. After welding of the last point (t. 9) in the first group, the computer issues a command to start the RCS3 in the second group and a command to compress one pair of electrodes from each transformer of the third group and a command to unclench the electrodes of the first group. After welding of the last point in the second group, the time counter for the duration of the flow of welding current in the RCS5 again issues a computer command. After that, the computer starts the welding of the first point in the third group and simultaneously compresses one pair of electrodes from each transformer of the fourth group, a command to unclench the electrodes of the second group and a command to move the electrodes of the first group to a new welding location. After welding of the third group is completed, the computer issues a command to the counter of the regulator of the fourth group - RCS9 and at the same time commands to expand the electrodes of the third group, to compress the electrodes of the first group and move the electrodes of the second group, etc. After welding of the last point in the last group, the computer counts the exposure time of the electrodes under pressure T2 after welding of the last point. The welding process on a multi-transformer welding machine ends.

Claims (2)

 1. A method for controlling the operation of a multi-transformer welding machine, including the simultaneous compression of one pair of electrodes from each transformer, the series connection of welding transformers, each of which is connected to a corresponding group of electrodes and a separate contactor, electrically connected to a multi-mode regulator of welding cycles, characterized in that all welding points and electrodes with a compression and displacement drive for welding these points at each post of a multi-transformer welding machine are separated and four groups combine the time of welding of the first group of electrodes with the time of compression of the electrodes of the second group, with the time of movement of the electrodes of the third group to the place of welding and with the time of unclenching of the electrodes of the fourth group, the countdown of the time of compression of the electrodes before welding and the exposure time of the electrodes under pressure after welding are performed at computer, moreover, the compression time of the electrodes before welding is set once for the first point in the first cycle, and the exposure time of the electrodes under pressure after welding is set after welding the last point n Latter-cycle.  2. A control circuit for the operation of a multi-transformer welding machine, containing controllers for welding cycles, a computer that determines the sequence of their work, thyristor contactors, the control inputs of which are connected to the outputs of the regulators of the welding cycles, and the outputs are with welding transformers, characterized in that the regulators of the welding cycles are equipped with each one counter for the duration of the flow of welding current, the computer outputs are connected to the inputs of the counters of the regulators, and the outputs of the counters are connected to the inputs of the computer.

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