SU499069A1 - Combined sensor - Google Patents

Description

one

The invention relates to the field of automation of welding processes, and specifically to position sensors of a welding head relative to a joint.

Combined sensors are known that are used to guide the welding head along the joint, which contain a magnetic flux injection unit in the products to be welded and a magnetic flux registration unit above the joint.

A combined sensor is known in which the magnetic flux detection unit is composed of a differential fluxgate, a selective amplifier, phase discriminators, a master oscillator, a frequency doubler, a smoothing filter, and a feedback circuit filter.

The disadvantage of the known combined sensor is the noise induced in the fluxgate by the magnetic field of the welding current and limiting the accuracy of the sensor. In addition, they can bring the amplifying path of the magnetic flux detection unit outside the linearity zone, which leads to the loss of useful information about the displacement of the sensor from the interface axis of the welded products.

In order to reduce the noise induced in the fluxgate by the welding current magnetic field, in the proposed sensor, an adder is connected to the magnetic flux recording unit and connected by one input to the output of the feedback circuit filter, and the output to the fluxgate. welding

current.

The drawing shows the functional scheme of the proposed sensor.

The combined sensor contains a block for inserting a magnetic sheet in the products to be welded and a block for recording magnetic flux. The input unit of the magnetic current is composed of an electromagnet 1 and a low-frequency generator 2, a nitrating electromagnet 1. The magnetic flux detection unit is composed of

differential fluxgate 3, designed to convert the movement of the sensor relative to the junction into an electrical signal, the amplifier-converter circuit of this signal and the value of feedback. Differential ferrosonde 3 contains two permalloy cores and a winding: wi - field winding, coa - output winding, with co - compensation winding. The excitation winding is connected to the driving oscillator 4. The amplifying-converting path is composed of a series-connected selective amplifier 5, a phase discriminator 6 receiving a reference voltage from a frequency doubler 7 connected to the driving oscillator 4, a phase

a discriminator 8 receiving the reference voltage from the low-frequency generator 2 and a smoothing filter 9. The feedback circuit is composed of a series-connected feedback circuit filter 10 connected to the output of the phase discriminator 6, and an adder 11 whose output is connected to the compensation winding ferrosonde 3. The adder 11 has a second input for connecting to the welding current source 12.

With the aid of a magnetic flux injection unit in the products to be welded, a variable magnetic flux Q of frequency is excited, which is scattered over the joint of the products. The component of the magnetic flux dispersion intensity, which coincides with the sensitivity axis of differential fluxgate 3, is proportional to the displacement of the sensor from the interface axis. Under the action of this component, an emf is induced in the output winding of the fluxgate. second harmonic of the form

e2 / cl; {2Соо-Q) Cos (2 (yo-I) t-

- (2со-f Q) Cos (2со + и), where: X is the displacement of the sensor from the butt axis, K. is the proportionality coefficient, and oo is the excitation frequency of the fluxgate.

The output signal of the differential flux probe is amplified by a selective amplifier 5 tuned to resonance at frequency 2 (yo and having a passband that captures the side frequencies 2 () oh and 2 (uo-f Q. The amplified signal is sequentially converted by voltage discriminators 6 and 8 into constant voltage). current proportional to the displacement of the sensor from the axis of the junction. Pulsations in the output voltage are suppressed by the smoothing filter 9.

In addition to the alternating magnetic field, excited by the magnetic flux input unit, ferrosonde 3 is affected by an external magnetic field, the main components of which are the constant magnetic field of the Earth and the magnetic field of the welding current. The differential ferrosonde 3 responds only to the component of the external magnetic field strength, which coincides with the sensitivity axis of the magnetic flux probe, and the magnetic field of the welding current is proportional to the welding current. Component

The intensity of the external field along the axis of the sensor is much higher than the amplitude of the variable component of the intensity of the diffusion flow above the joint. High voltage

A second harmonic at the input of the selective amplifier 5, proportional to the intensity of the external magnetic field, can cause an overload of this amplifier. To avoid this, automatic compensation is provided in the external magnetic field flux-gate volume, which is achieved by passing a compensation current through the compensation flux of the flux-gate material, which is formed in the adder 11, as the sum of the currents supplied to

from the filter 10 of the feedback circuit and the source 12 of the welding current. Component of the compensation current supplied to the adder

11c of the feedback circuit filter 10 leads to the compensation of a constant external magnetic field. To compensate for the magnetic field of the welding current, a portion of the welding current is supplied to the adder 11 and removed from the source.

12 welding current.

The tests of the combined sensor, carried out during the welding of magnetic materials with a constant and pulsating current, have shown that the proposed scheme of the sensor makes it possible to reduce the noise induced by the welding current in the ferrosonde.

Claims (1)

Invention Formula A combined sensor comprising a magnetic flux input unit and a magnetic flux detection unit composed of a differential ferrosonde, a selective amplifier, phase discriminators, a master oscillator, a frequency doubler, a smoothing filter and a feedback circuit filter, characterized in that, in order to reduce interference, induced in the fluxgate by the magnetic field of the welding current, an adder connected by one input to the output of the filter of the feedback circuit, and the output to ferro NDU, the second input of the adder is used for connecting it to the welding power source.