KR101670690B1

KR101670690B1 - Current sensing device for welding monitering device

Info

Publication number: KR101670690B1
Application number: KR1020150051330A
Authority: KR
Inventors: 심성수
Original assignee: 심성수
Priority date: 2015-04-11
Filing date: 2015-04-11
Publication date: 2016-10-31
Also published as: KR20160121342A

Abstract

An object of the present invention is to provide a current sensing device for a welding monitoring device capable of precisely detecting a secondary current of a welding machine.
In order to achieve the above object, the present invention provides a current sensing device for a welding monitoring device for measuring a current of a welding current at a welding current monitoring device, the current sensing device comprising: Moon coil; An integrator for integrating the electromotive force generated in the Troy month coil; An A / D converter for digitally changing an output signal of the integrator; A comparator having an input of an electromotive force generated from the Trojan coil; A counter having an output of the comparator as an input; And a processor for calculating a welding current at the welding machine using the signal of the counter and the signal of the A / D converter.

Description

Technical Field [0001] The present invention relates to a current sensing device for a welding monitoring device,

The present invention relates to a current sensing device for a welding monitoring device, and more particularly to a current sensing device for a welding monitoring device applicable to a welding monitoring device.

Generally, welding, especially spot welding, is also referred to as spot welding, and is mainly used for welding a plate material. In principle, a welding material is inserted between electrodes, and a pressure is applied to the pressing portion by resistance heat Is used as a welding method.

In order to improve the quality of the spot welding as described above, it is necessary to appropriately adjust the pressing force, the energizing time, and the current density. For example, if the pressing force is large, the contact resistance is decreased and the welding progress is not good. If the pressing force is large, sparks appear when passing the current, and the welding progress is not good and the electrode and the welding surface are infringed.

The welding surface should be clean and flat, and no solvent is used. The welding time is very short because the heating area is narrower than the butt welding. In addition, when reaching the welding temperature, when the pressure is increased, the welded part weakens as it enters the concave part. If the pressure is weak, it is impossible to complete the welding, and if the above conditions are not satisfied, welding failure occurs.

In addition, in the industrial field, there is a case where the quality change of the raw material and the working conditions cause the change of the entrance, and such a change of the welding environment causes the welding failure. However, since there is no separate monitoring device, Quality control is carried out.

In addition, the spot welder itself includes functions such as control of electrical characteristics, etc. However, the welder usually controls the power of the primary side so that it is somewhat difficult to monitor the characteristics of the welding base material.

In order to overcome such disadvantages, Patent No. 760513 has been proposed. The present invention relates to an automatic monitoring apparatus for an optimal condition for welding a spot welder, and more particularly, to a welding current measuring unit for measuring a welding current during spot welding; A welding current display unit for displaying the welding current measured by the welding current measuring unit; An upper / lower limit setting unit for setting an upper / lower limit value of the welding current; An upper / lower limit display unit for displaying upper / lower limit values set by the upper / lower limit setting unit; A warning light display lamp divided into an upper limit alarm operation, a lower limit alarm operation and a normal operation according to a comparison result between the measured welding current and predetermined upper and lower limit values; And a main MCU for controlling the operation of the automatic light monitoring device, the main MCU controlling the operation of the beacon lamp according to a result of comparing the welding current measured by the welding current measuring unit with predetermined upper and lower limit values; It is possible to monitor the occurrence of defects caused by changes in raw materials or work conditions that may occur in the spot welding operation used in an industrial field, thereby providing effects such as the original prevention of defective products from being dispatched .

The above-mentioned patent has an advantage of being able to monitor the welding state by measuring the welding current, especially the secondary current of the spot welding and managing the upper limit value, and is mounted and used in a facility including the spot welding process.

Meanwhile, the spot welding monitoring apparatus as described above uses a Troyundo coil (Rogowski coil) as a sensor for measuring a secondary current. The coil is wound in the circumferential direction of the wire through which the secondary current of the toroidal coil flows, and the secondary current value is sensed based on the voltage induced in accordance with the current. Thus, even if there is no electrical connection to the welding machine itself, There is an advantage that the current can be detected.

The voltage induced in the Rogowski coil is first integrally integrated through an integrator, converted into a digital signal by A / D conversion, and then input to a signal processor to perform a monitoring function.

In this case, the spot welder can be divided into an AC type and a DC type. In the case of the AC type, the current sensing method using the Troy month coil can detect relatively accurate values. However, in the case of the DC type, Therefore, there is a disadvantage in that the monitoring function is performed based on the relatively estimated value since the accurate current value can not be measured.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a current sensing device for a welding monitoring device capable of precisely detecting a secondary current of a welding machine.

In order to achieve the above object, the present invention provides a current sensing device for a welding monitoring device for measuring a current of a welding current at a welding current monitoring device, the current sensing device comprising: Moon coil; An integrator for integrating the electromotive force generated in the Troy month coil; An A / D converter for digitally changing an output signal of the integrator; A comparator having an input of an electromotive force generated from the Trojan coil; A counter having an output of the comparator as an input; And a processor for calculating a welding current at the welding machine using the signal of the counter and the signal of the A / D converter.

Advantageously, the output of the Trojan coil is processed by a differential amplifier, and the output of the differential amplifier is provided as an input to the integrator and the comparator.

More preferably, the output of the differential amplifier is processed by a low-pass filter, and the output of the low-pass filter is provided as an input of the integrator and the comparator.

More preferably, the processing apparatus calculates the duty ratio of the secondary current of the welding machine by the counter, and calculates the magnitude of the secondary current of the welding machine by the A / D converter.

More preferably, the processing apparatus is a main processor of a welding monitoring apparatus.

The current sensing device for a welding monitoring device according to the present invention includes a configuration that can be applied to a direct current welding device. In particular, in the direct current method, the current applied to the secondary side of the welding device is precisely detected to improve the monitoring precision of the welding monitoring device Further, when the welding monitoring apparatus as described above is applied to a welding machine, it is possible to produce a high quality product.

1 is a configuration diagram of a current sensing device for a welding monitoring device according to the present invention,
FIG. 2 is a configuration diagram showing an output waveform change according to the comparator shown in FIG. 1,
3 is a cycle of a waveform sensed by the counter shown in FIG. 1,
FIG. 4 is a configuration diagram of a welding monitoring apparatus to which FIG. 1 is applied.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

Although the present invention can be applied to any welding machine driven by electric power, it will be described for the convenience of explanation only for a spot welding machine, but it is obvious that the scope of the right is limited to a spot welding machine.

1, a current sensing device 100 for a welding machine according to the present invention includes a Troy month coil 10, a differential amplifier 10 connected to the Troy month coil 10, a differential amplifier 20, An integrator 40 which is connected to the output side of the low-pass filter 30 and integrates the signal, an A / D converter (not shown) which converts the output signal of the integrator 40 into a digital signal A counter 70 for detecting a time interval of an output signal of the comparator 60 and a counter 70 for detecting a time interval of the output signal of the comparator 60. The counter 70 is connected to the output of the low- And a processing unit 90 for calculating a current by using the signal of the integrator 40 and the signal of the integrator 40.

First, the Troy month coil 10 is composed of a conventional Rogowski coil mounted on the secondary side of the spot welder and generating an induced electromotive force in proportion to the current applied to the secondary side of the welder.

The Troy month coil 10 is configured such that one side is wound with a coil outside the annular type of the derivative.

In this case, the induced electromotive force is in the form of a pulse in the case of the direct current method, but it is general that the induced electromotive force is distorted by adding noise or the like due to the surrounding environment and the response characteristic of the Troy month coil 10.

The output of the Troy month coil 10 is input to the differential amplifier 20. The differential amplifier 20 is configured in such a manner that the output side of the differential amplifier 20 recovers to the input thereof, thereby eliminating the noise of the output signal of the Troy month coil 10.

Accordingly, the signal output from the differential amplifier 20 is in a state in which noise is removed from the output signal of the Troy coil 10.

The output signal of the differential amplifier 20 is filtered by a low-pass filter 30 to remove a high-frequency component. A signal that has passed through the low-pass filter 30 is primarily filtered by the differential amplifier 20 Since the high-frequency component is further removed through the low-pass filter 30 after the removal, the signal interlocked with the welder secondary-side current signal is output relatively accurately.

The output of the low-pass filter 30 is integrated through the integrator 40 and output. At this time, the signal output from the integrator 40 is an RMS value because the electromotive force generated in the Troy coil 10 is finally integrated. That is, the RMS value of the current applied to the secondary side of the welding machine can be calculated.

Meanwhile, the signal output from the low-pass filter 30 is transmitted to the comparator 60. The comparator 60 serves to regenerate some distorted pulse waveforms as normal pulse waveforms, as shown in FIG.

Therefore, the signal output from the comparator 60 is in the form of an accurate pulse.

The output of the comparator 60 is input to the counter 70. The counter 70 senses the interval between the pulses and the pulse in units of time as shown in FIG. The period of the pulse and the width of the pulse can be sensed.

That is, the duty ratio of the DC current applied to the secondary side of the welding machine can be accurately detected through the combination of the comparator 60 and the counter 70.

Therefore, the processing device 90 senses the magnitude of the current through the integrator 40 and senses the duty ratio of the secondary side current of the welder through the counter 70, so that the current finally applied to the secondary side of the welder Can be accurately detected.

As shown in FIG. 4, the current sensing device 100 for a welding machine according to the present invention comprises a sensing part for sensing a secondary side current characteristic of a welding spot among the spot welding monitoring devices, The welding characteristic, the number of energized water, etc., by using the current characteristic of the welder detected through the spot welding process. At this time, the processing device 90 is preferably implemented using a main processor included in the spot welding monitoring device.

Of course, the present invention can be applied to other electric welders in the same manner as described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, And all of the various forms of embodiments that can be practiced without departing from the technical spirit.

10: Troydal coil 20: Differential amplifier
30: Low-pass filter 40: Integrator
50: A / D converter 60: comparator
70: counter 90: processing device
100: Current sensing device

Claims

A current sensing device for a welding monitoring device for measuring a welding current at a secondary side of the welding device and providing the same to a welding monitoring device,
A toroidal coil in which an induced electromotive force is generated by a welding current applied to a secondary side of a welding machine;
An integrator for integrating the electromotive force generated in the Troy month coil;
An A / D converter for digitally changing an output signal of the integrator;
A comparator having an input of an electromotive force generated from the Trojan coil;
A counter having an output of the comparator as an input; And
And a processor for calculating a secondary current of the welding machine using the signal of the counter and the signal of the A / D converter,
Wherein an output of the differential amplifier is provided to an input of the integrator and a comparator,
Wherein the output of the differential amplifier is processed by a low pass filter and the output of the low pass filter is provided as an input to the integrator and the comparator.

delete

The welding apparatus according to claim 1, wherein the processing device calculates the duty ratio of the welding current at the welding current source by the counter, and calculates the magnitude of the welding current at the welding current source by the A / D converter Device.

The current sensing device for a welding monitoring device according to claim 4, wherein the processing device is a main processor of a welding monitoring device.