SU1324800A1 - Instrument transducer of welding current - Google Patents

Abstract

The invention relates to equipment for measuring welding process parameters and is intended to measure welding current on resistance welding machines. The aim of the invention is to reduce the measurement error of the welding current. The error due to transients in the current sensor is eliminated by the sampling-storage device, at the output of which, the voltage before the next measurement is equal to the residual output voltage of the function block from the previous measurement. At the adder, the magnitude of this voltage is subtracted from the voltage coming from the functional unit during the measurement. This ensures high accuracy of measurements at any period following welding pulses. Elimination in the current-free pause of interference to the recording device is achieved by using an electrode position sensor, the output of which is connected to the control input of the sampling-storage device. 2 pe. (L O9 to 4 00

Description

eleven

The invention relates to equipment for measuring the parameters of the welding process and is intended to measure the welding current on resistance welding machines.

The method of the invention is to reduce the measurement error of the welding current.

Figure 1 shows a block diagram of a welding current measuring transducer; Fig. 2 is a schematic diagram of a current transducer.

The device contains a current sensor 1 (Fig. 1), to the output of which the functional unit 2 is connected, an adder 3, a sampling-storage device 4, the inputs of which are connected to the output of the functional unit 2, and an electrode position sensor 5, the output of which is connected to the control the input of the sampling-storage device, the output of the sampling-storage device is connected to the inverter input of the adder.

In the welding current measuring transducer (fng.2), a current sensor with non-magnetic gaps in the magnetic conductor is used as a current sensor, which ensures the linearity of the magnetization characteristic of the transformer. Functional block 2 consists of an integrator 6 with an offset limiter 7 and an adder 8 The inverting inputs of the integrator and adder are connected to shunt 9 in the secondary circuit of the current transformer, the non-inverting input of the adder is connected to the integrator's output, the output of the adder is the output of the functional unit and connected to the device input 4 samples and the inverting input of the adder 3, the non-inverting input of the adder 3 is connected to the output of the sampling-storage device. The electrode position sensor 5, the output of which is connected to the control input of the sampling-storage device, contains a comparator 10 on the basis of an operational amplifier, supplying a positive polarity + EOV, which through RC circuit 11 and microswitch 12 is connected to the zero level bus.

Measuring converter welding current works as follows.

With diluted electrodes, the electrode position sensor is formed

248002

Control signal for the sample storage device. At the same time, it is in the sampling mode, i.e. the voltage on its input and output is equal to

 between themselves. As a result, the two inputs of the adder (inverting and non-inverting) receive the same voltage voltage and are subtracted, which provides a zero value

fO of the output voltage, and therefore excludes the passage of a non-informative signal.

When the electrodes are closed, the electrode position sensor generates a signal on the pack 5, which transfers the storage sampling device to the storage mode, i.e. the voltage at its output is equal to the voltage at the output of the functional unit, which was at the time of switching. When a welding current appears, the signal from the output of the current sensor is fed to the input of the functional converter. From the output of the function block, the voltage goes to the adder, where the output voltage of the sample-hold device, i.e. residual voltage after the previous measurement.

thirty

When the electrodes are spread, the sampling-storage device goes back into sampling mode and zero is maintained at the output of the adder.

jj is the value of the output voltage.

In the example of implementation of the proposed device (FIG. 2) with the diluted electrodes, the microswitch 12 is open, the voltage

40 non-inverting input of the operational amplifier is applied directly to the inverting - via a voltage divider. From the output of the operational amplifier voltage

45 of the positive polarity is applied to the control input of the sample-storage device, which provides the sampling mode. When the electrodes are closed, the microswitch grounds the noninverting input of the op amp. At the output of the operational amplifier, the voltage changes polarity, so that the sampling and storage device is put into storage mode55. RC circuit AND provides protection against mechanical bounce of the microswitch. Thus, the electrode position sensor provides control of the storage sampling device.

The voltage from the mount 9, proportional to the secondary current, is fed to the inverting inputs of the integrator 6 and the adder 8, the voltage at the integrator's output is proportional to the magnetizing current. The integrator bias limiter 7 ensures stable operation of the functional unit. At the output of the adder 8, as a result of the addition of voltages proportional to the magnetizing current and the secondary current, a voltage proportional to the primary current is obtained.

Thus, due to the continuous operation of its auto-tuning function block at the output, realized with the help of a sampling-storage device and an adder, the welding current measuring transducer provides high accuracy of measurement

four

any period of the pulse.

la invention

A welding current transducer containing a current sensor and a functional unit connected to the output of a current sensor, characterized in that, in order to reduce the measurement error of the welding current, an electrode position sensor, a sampling-storage device and an adder, the inverting input of which is connected to the non-inverting function block output — with the output of the sample storage — the signal input of the sampling storage device is connected to the output of the function block, and the control input — with the output m electrode position sensor.

Vshod

I bbtxod

Claims (1)

Claim 5 A welding current measuring transducer comprising a current sensor and a functional unit connected to the output of a current sensor, characterized in that, in order to reduce the measurement error of the welding current, an electrode for positioning the electrodes, a sampling-storage device and an adder with an inverting input connected to it 15 with the output of the functional block, non-inverting - with the output of the sampling-storage device, the signal input of the sampling-storage device is connected to the output of the functional 20 units, and the control input with the output of the electrode position sensor.