CZ308321B6 - Measuring set for continuously evaluating quality during robotic welding - Google Patents

Abstract

The measuring assembly for continuously evaluating the quality of robotic welding seams includes intelligent sensors (IS), industrial or personal computer (O) with touch screen for operator access to the measured data, network server (P) for data acquisition, and operator computer (O ) connected to a local area network (LAN). The intelligent sensor (IS) comprises two main electronic circuits, forming an analogue part and a digital part, the analogue part is electrically connected to measure electric current by a converter (11) to a conductor (1) passing through the sensor (IS) and in which the electronic circuits for filtering the voltage input signal are located in this analogue part, when the direct connection of the intelligent sensor (IS) to the positive and negative poles of the power source is used to measure the arc voltage. The digital part of the intelligent sensor (IS) includes a CPU processor motherboard, RAM, analogue / digital converters (10, 12), and an interface with the module (15) for Ethernet communication and LAN and POE power. The currently measured weld data is temporarily stored in RAM and after measurement is sent to the operator computer (O) for evaluation.

Description

The invention relates to the field of inspection devices for detecting weld defects during welding, in particular for robotic welding.

Prior art

Defects in welds can be caused by insufficient preparation of welded parts, especially insufficient preparation of welded surfaces, incorrect assembly of welded parts, incorrect welding procedure, non-compliance with technological procedure, etc., or hardening of the weld - cooling of the weld pool when internal stress arises.

Weld inspection is therefore one of the necessary operations related to the production of welded parts. The level of inspection varies according to customer requirements, standards, purpose, etc. Destructive tests are used for inspection, which serve primarily to verify the production technology or to inspect a sample from the production series, as well as non-destructive tests and methods to inspect the resulting weld without it has been damaged. Non-destructive methods can be applied to every weld of each product.

Surface defects of welds are most often inspected visually or by capillary method. Internal weld defects are usually detected by X-ray or ultrasound imaging. Tests, both destructive and non-destructive, are usually specified by the relevant technical standard.

In addition to the above-mentioned inspections intended for already created welds, methods are also known which continuously monitor the formation of a weld. Continuous (on-line) monitoring of welds is one of the non-destructive methods that can significantly reduce the need for non-destructive inspections of created welds, or even completely replace them. They are used mainly in mass production in robotic workplaces, where these methods are faster and cheaper.

The continuous methods used so far can then be divided into two groups. These are, on the one hand, methods which use sensors to evaluate the resulting weld and, on the other hand, methods which use sensors to monitor the parameters of the welding process.

The first group includes methods which, based on the measurement of the specified physical quantities of the weld created, monitor the course of its formation and compare it with the course of the previously measured flawless weld. Based on the deviations, it is determined whether the weld is OK or defective. These known methods include Measurement of acoustic emission, Thermovision inspection of welded joints, Continuous inspection of the welding process using spectrometry, Measurement of the ultraviolet component of emerging welds and others.

The second group includes methods which, on the basis of continuous measurement of the parameters of the welding apparatus, monitor the process of weld formation and compare it with the course of the previously measured flawless weld. These known methods include measurement of welding voltage and current, measurement of the length of the unwound wire, measurement of the amount of protective atmosphere gas and others.

The essence of the invention

The object of the present invention is to present a new concept of a measuring set for continuous quality control of welds with the connection of an internal intelligent sensor, enabling the connection of an intelligent sensor to the positive or negative pole of a welding source for measurement.

- 1 CZ 308321 B6 welding current and welding voltage, and at the same time enabling the connection of one or more of these intelligent sensors to a measuring set for measuring welds, in particular during robotic welding.

Measuring set for continuous evaluation of weld quality, especially in robotic welding, including intelligent sensors, the number of which in the measuring set depends on the number of connected robotic manipulators and welding sources in one welding cell, industrial or personal computer with touch screen for operator access to measured data, a network server for collecting measured data, and an operator computer-connected local area network (LAN) according to the present invention, the essence of which is that the intelligent sensor consists of two main electronic circuits, a first, an analog electronic circuit and a second, digital electronic circuit, a first, analog electronic circuit used for measuring electric current by means of a current / voltage and voltage converter is electrically connected to a conductor passing through an intelligent sensor, said first, analog electronic circuit comprising at least one filter for filtering the input voltage signal, and further includes analog / digital converters when a direct connection of an intelligent sensor to the positive and negative poles of a welding source is used to measure the electric voltage of the welding arc. The measurement of the electric current is then preferably realized by a so-called Hall probe or by means of a shunt. The second, digital electronic circuit of the intelligent sensor, includes a motherboard with a CPU, RAM, and an interface with a module for Ethemet communication and power on ethemet (POE).

In the preferred embodiment, the currently measured weld data are temporarily stored in the RAM memory and, after the measurement is completed, are sent to the operator computer for their evaluation.

The intelligent sensor further comprises input and output connectors for welding cables for connecting this intelligent sensor to the welding circuit and for connecting the sensor directly to the welding source, and a system, preferably a mechanical switch, for selecting the welding voltage signal source as internal or external. wherein the intelligent sensor can be connected to the positive or negative pole of the welding source. The electronic devices included in the intelligent sensor allow its easy connection to the welding circuit. The connection of the intelligent sensor to the positive pole of the welding source also allows the voltage to be measured directly in the intelligent sensor. When connecting the intelligent sensor to the negative pole of the welding source, it is then necessary to bring the signal source from the positive pole of the welding source to the intelligent sensor. For this purpose, the intelligent sensor is then equipped with a connector for connecting a wire with a positive welding voltage signal, and an external voltage signal source is then selected by the included mechanical switch.

A measuring assembly comprising these intelligent sensors, preferably 1 to 4 pieces of intelligent sensors per welding cell, serves to process and analyze the course of welding current and voltage from several welding sources simultaneously, and its further advantage is easy connection of a measuring assembly containing intelligent sensors. , with the current welding infrastructure in manufacturing companies.

For the selected internal design of the intelligent sensor, it is possible to work in practice in two modes and their combinations, when in the first mode the intelligent sensor can record only welds or, in the second mode, can directly evaluate these welds and inform the superior unit of possible weld defect. and upon request, send a complete record of the defective weld for detailed analysis. In this mode, the intelligent sensor can also start recording the faulty weld in the mode of simply recording voltage and current waveforms and then continuously read the recorded waveforms from the master system via TCP / IP communication. These waveforms are then evaluated separately by the operator's workplace.

The sensor part is able to record current and voltage with a frequency of up to 40 kHz, which is optimal for evaluating the welding method CMT (cold metal transfer), while its own

-2 GB 308321 B6 the measurement of the course of welding current and voltage takes place automatically. Automatic measurement simplifies the operation of the welding cell.

In the case of a predefined sequence of welds, this measuring set comprising at least one intelligent sensor allows the welds to continuously evaluate independently and immediately transmit information about the detected weld defect to the robotic workplace control system (PLC) and then send a weld log via Ethernet on request.

From the measured data, the individual welded joints on the weldment can be automatically analyzed in the operator's computer, and the operator can display information on the status of individual welds of the current weldment in a simplified form on the display panel. Using Ethernet and POE (power on ethemet) interfaces, it is also easy to integrate a measurement set including intelligent sensors into a corporate network, including remote management and data storage in a central database.

Explanation of drawings

The invention will be explained in more detail with the aid of the drawings, in which FIG. 1a shows a diagram of a measuring assembly and FIG. 1b shows a detail of a circuit diagram of an intelligent sensor; FIGS.

Examples of embodiments of the invention

Example 1

The measuring assembly according to Fig. 1a comprises an intelligent sensor ISi, .. _n and is used to measure electrical voltage and current during pulsed and conventional arc welding (MIG / MAG, TIG / WIG, CMT cold metal transfer). The welding circuit is composed of welding sources Ci ... _n , which are connected to the welding table B, and electrodes in robotic manipulators Ai ... _n . The earth cable G is connected at one end to the negative poles of the welding sources Ci, .. _n and at the other end to the welding table B. The cables Fi .., _n and Di ... _n connect the positive poles of the welding sources Ci ... n to the welding electrodes in robotic manipulators Ai ... _n . Connection of Fi, .. _n and Di cables. not implemented by intelligent sensor ISi, .. _n . Di .. _n cables are not mandatory in the set if the ISi, .. _n sensors are connected by connectors 2 or 3 directly to the Ci ... _n welding sources.

The intelligent sensor ISi, .. _n according to Fig. 1b is composed of two interconnected, mechanically separable electronic circuits, an analog electronic circuit R and a digital, digital, electronic circuit S placed in an electrically non-conductive insulating housing.

Intelligent sensor ISi.,. _n passes an electric conductor 1, which is galvanically connected to the external connectors 2 and 3. Connectors 2 and 3 serve to connect the electric conductor Di _n from the welding source Ci, .. _n and the electric conductor Fi .., _n from the robotic manipulator Ai ... _n .

The galvanic connection 4 between the mechanical switch 5 and the conductor j is realized by the module 18. The module 18 is composed of a slip ring or torsion spring which ensures electrically conductive contact with the through conductor in order to transmit the welding voltage signal from the internal environment of the intelligent sensor to the mechanical. switches 5. In the event that the zero signal of the welding source passes through the conductor 1, the galvanic connection 4 can be interrupted thanks to the module 18. The electrical conductor 6 is galvanically connected to the electrical conductor F in order to transmit the welding voltage signal from the external environment to the mechanical switch 5 via the connector 7. In this exemplary embodiment of the invention, the connection by the conductor 6 is not realized due to redundancy. The sensor components marked with the Rj area are part of the analog electronic circuit.

-3 CZ 308321 B6

The mechanical switch 5 is used to select the signal source (internal or external signal source) of the welding voltage. The welding voltage signal then proceeds to the analog module 8 for filtering and basic signal conditioning. The filtered welding voltage signal then proceeds to the signal amplifier module 9. The modified and filtered welding voltage signal enters the analog / digital converter 10.

The welding current is measured by means of a current / voltage converter 11, through which an electric conductor L passes. The electric signal of the welding current is further transmitted to an analog / digital converter 12. The sensor components marked by area S are part of a digital electronic circuit.

The electronic circuit with the processor 13 is connected to both converters 10 and 12. from which it reads data. The processor communicates with the RAM 14 in which it stores the measured data. The Ethernet communication module 15 for UAN is used to transmit measured data to the superior control system O, to which it is connected by UAN cable E and M via network switch N. Connector 17 connected to digital outputs of the processor is used for digital communication with industrial logic controller (PEC) O using Hi ... _n wires. The industrial logic controller Q is connected primarily to the robotic manipulators Ai .. _n by means of wires Ji, .. _n and serves to control them. The secondary connection of the Q controller to the ISi, .. _n sensors and the industrial computer O via the Hi .. _n and E data wires is an optional accessory for the entire measuring set. Communication between the Q controller and the industrial computer O can also be implemented via the Ethemet UAN interface.

The industrial computer O is used to monitor the progress of the welding process and to evaluate the quality of welds using ISi, .. _n sensors in real time. It is located near the welding cell K.

The collected welding data can be transferred from the operator computer O to the data server P using the industrial computer network ΕΑΝ I.

Example 2

The measuring assembly according to Fig. 2 comprising the intelligent sensor ISi ... _n differs from the exemplary embodiment given in Example 1 in that the sensors ISi ... _n are connected to the ground cable G in such a way that the sensors ISi ... _n are in the assembly connected to the negative poles of welding sources Ci ... _n . This connection does not allow to measure the welding voltage directly from the conductor 1 passing through the sensor. Therefore, the electric wire 6 is galvanically connected to the electric wire F in order to transmit the welding voltage signal from the external environment to the mechanical switch 5 via the connector 7. If the zero signal of the welding source passes through the wire 1, the galvanic connection 4 can be interrupted and the source the welding voltage signal is obtained by a mechanical switch 5 from the conductor 6.

Example 3

The measuring assembly according to Fig. 3 comprising an intelligent sensor ISi. _n differs from the exemplary embodiment given in Example 1 in that the sensors ISi ... _n are not connected to the controller Q and there is no digital communication.

Example 4

The measuring assembly according to Fig. 4 comprising an intelligent sensor ISi. _n differs from the exemplary embodiment shown in Example 3 in that the industrial computer O is not connected via data wires to the controller Q and there is no digital communication.

-4 CZ 308321 B6

Example 5

The measuring assembly according to Fig. 5 comprising an intelligent sensor ISi. _n differs from the exemplary embodiment given in Example 2 in that the sensors ISi, .. _n are not connected to the controller Q and there is no digital communication.

Example 6

The measuring assembly according to Fig. 6 comprising an intelligent sensor ISi. _n differs from the exemplary embodiment given in Example 5 in that the industrial computer O is not connected via data wires to the controller Q and there is no digital communication.

Example 7

The measuring assembly comprising the intelligent sensor ISi .., _n differs from the exemplary embodiment given in Examples 1, 2, 3, 4, 5 and 6 in that the database server P is not part of the assembly and the industrial computer Oje is the final element of the measuring assembly.

Industrial applicability

The intelligent sensor is designed to measure voltage ± 300 V and current ± 400 A with a frequency up to 40 kHz. It can be applied not only to the conductors of welding circuits, but also to any device with the need for short-term measurement of the course of electrical quantities. For example, these are the conductors of powerful electric motors in working machines such as lathes, milling machines, planers, saws, etc.

The intelligent sensor can also be used as a control device for monitoring the load or overload of an electrically driven work machine.

Claims (3)

PATENT CLAIMS A measuring set for continuous evaluation of the quality of robotic welding welds, comprising in its connection intelligent sensors (ISi ... n), an industrial or personal computer (O) with a touch screen for operator access to the measured data, a network server (P) for collecting measured data, wherein the operator computer (O) is connected to the local computer network LAN (I), characterized in that the intelligent sensor (ISi ... _n ) consists of two main electronic circuits, the first, the analog electronic circuit (R) and a second, digital electronic circuit (S), wherein the first, analog electronic circuit (R) is electrically connected to a conductor (1) passing through an intelligent sensor (ISi ... _n ) for measuring electric current and electric voltage from a welding source and comprises analog / digital converters (10 and 12), and the second, digital electronic circuit (S) of the intelligent sensor (ISi ... _n ) comprises a base plate with a CPU (13), RAM (14), and an interface with a module ( 15) for Ethemet communication and POE power supply. Measuring assembly for continuous evaluation of robotic welding weld quality according to claim 1, characterized in that the first, analog electronic circuit (R) of the intelligent sensor (ISi ... n) comprises at least one electronic filter (8) for filtering the input voltage signal , an electrical signal amplifier (9) and a mechanical switch (5) enabling the selection of the welding voltage signal source, wherein a direct connection of the intelligent sensor (ISi ... _n ) to the positive and negative poles of the welding source is used to measure the electric voltage of the welding arc -5 CZ 308321 B6 and the electrical connection of the analog electronic circuit (R) for measuring electric current and electric voltage with the conductor (1) passing through the intelligent sensor (ISi ... _n ) is realized by means of a current / voltage converter (11). A measuring assembly for the continuous evaluation of the quality of robotic welding welds according to claim 2, characterized in that the intelligent sensor (ISi ... _n ) further comprises input and output connectors (2 and 3) for welding cables for connecting said intelligent welding. sensor (ISi ... _n ) into the welding circuit, the intelligent sensor (ISi ... _n ) being connected to the positive pole of the welding source by electrical conductors (Di .. _n ) and a conductor (Fi .. _n ) or to the negative pole of the welding ίο sources (Ci. n) by electric conductors (Di ... _n ) and conductors (G).