WO2016044874A1

WO2016044874A1 - Method for monitoring an arc process carried out by a burner, and device for carrying out said method

Info

Publication number: WO2016044874A1
Application number: PCT/AT2015/050236
Authority: WO
Inventors: Daniel ANGERMAYR; Günther REINTHALER
Original assignee: Fronius International Gmbh
Priority date: 2014-09-24
Filing date: 2015-09-24
Publication date: 2016-03-31
Also published as: AT515916B1; AT515916A4; DE102015211335B4; DE102015211335A1

Abstract

The invention relates to a method and a device for monitoring an arc process carried out by a burner (1), in particular a welding process, wherein the burner (1) moves along a processing path (x), and images (P_i) of the surroundings of the arc (2) are captured with a refresh rate (f_B), using a monitoring system (3) connected to the burner (1) and having at least one camera (4), and the images (P_i) are displayed on a display device (10), wherein, with the refresh rate (f_B), at least two images (P_ij) having a different exposure time (t_Bj) are captured after one another. In order to improve the quality of the captured images, despite the very bright arc (2), sections (P'_ij) are cut out of each of the at least two images (t_ij) having a different exposure time (t_Bj), and combined with an assembled image (Ρ''_i), and the assembled image (Ρ''_i) is displayed.

Description

A method of monitoring an operation performed by a burner arc process and apparatus for carrying out Ver ^¬ proceedings

The invention relates to a method for monitoring an operation performed by a burner arc process, particularly the welding process, the burner performs a movement along a processing path, and connected by means of the burner, at least one camera comprising Überwachungssys ^¬ tems images of the surroundings of the arc with a Refresh rate will be recorded and the pictures on one

Display device are shown, with the refresh rate in succession at least two images are recorded with different exposure time.

Furthermore, the invention relates to a device for carrying out above-mentioned method for monitoring a process performed with a movement along a machining path exporting burner arc process, in particular Schweißpro ^¬ zesses, connected to a with the burner, at least one camera comprehensive monitoring system for producing images of the environment the arc with a Bildwiederholfre ^¬ quency, a display device for displaying the images, and with a device for controlling the monitoring system for receiving at least two images with the refresh rate and different exposure time in a row.

Systems for monitoring arc processes, especially welding processes, using cameras are already well known. The images recorded during the monitoring process can be used to observe the work process, in particular the welding process, and influence parameters. For example, WO 2012/119170 A1 describes a method and a device for monitoring an arc process, in which the burner performs a pendulum motion.

JP 2001 138049 A describes a method for monitoring a machining process, wherein the machining area is recorded with two cameras with different exposure times and an image processing from these pictures created artificial image and the display is displayed.

In the observation of arc processes with a camera that resulting from the very high light intensity of the Lichtbo ^¬ gene due to the high dynamic range of the monitored area is a fundamental problem. The dynamic range is the ratio of the largest to the smallest light intensity, ie the ratio of extremely high radiation intensity of the arc to the particularly low intensity around the light ^¬ arc. With ordinary cameras, such a dynamic range can not be achieved. Special HDR (High Dynamic Range) cameras are also rarely able to represent an arc process to peacefully ^¬ and are also very expensive. The use of high-speed cameras with a particularly high frame rate and low exposure time is also eliminated due to the size of such cameras and the cost.

Also covering the area of the arc would allow for ei ^¬ ner reducing the dynamic range, however, is undesirable since this could not be observed relevant areas of the arc process. For the observer, however, the entire context of the arc process is of importance, which in the case of a welding process from the end of the arc

Welding wire over the arc, the molten pool, the sweat ^¬ seam and the surrounding area extends.

The object of the present invention is to provide a method and an apparatus for monitoring an operation performed by a burner arc process by which a better visual recognition of the monitored arc process can be achieved, despite the large differences in brightness in ^¬ nerhalb of the observed area. The on ^¬ wall and the size of such a device should

be as low as possible. Disadvantages of known methods and devices should be avoided or at least reduced.

The object of the invention is achieved in terms of the method in that sections of each of the at least two images with different exposure time are cut out and combined into a composite image, and the composite image is displayed on the display device. The present invention therefore combines at least two images taken in succession with different exposure times and simultaneously displays them on the display device. Thus is able through the different exposure times both the areas with high light intensity and the Be ^¬ rich are displayed optimally with low light intensity and the user, both places with high

To look at light intensity as well as places with low light intensity optimal and draw appropriate conclusions from the pictures. A special HDR camera to handle the large dynamic range or an expensive high-speed camera is not required. By combining several images with different exposure times relatively inexpensive cameras (for example, cameras in CMOS technology) can be used with ge ^¬ ing size, which can be attached to the burner, in particular welding torch. An image is composed of several subregions, which subregions are formed from the images with different exposure time. For example, the region of the arc, the ^¬ cherweise is übli in the middle of the entire image, formed from a ent ^¬ speaking lying in the middle portion of the image having the lowest exposure time, whereas the more distant from the arc ranges from partial areas of the images with the higher exposure times are formed. Such a composite image provides the viewer both in the areas with high light intensity and in the preparation ^¬ chen with low light intensity high contrast and optimal image quality, so from all of the assembled ^¬ compound image areas conclusions about the arc process can be made.

Advantageously, the at least two images are captured with an exposure time which is less than the Bildwiederholperiodendauer defined by the image ^¬ repetition frequency, preferably between 0.01 ms and 20 ms. The maximum Belich ^¬-up time is defi ^¬ ned by the used refresh rate. For example, the maximum exposure time at a standard refresh rate of 50 Hz is 20 ms. The subregions can be formed, for example, by circular surfaces or circular rings. Such a configuration of the partial areas ^¬ is preferred, although other shapes, ^¬ example, square regions, or other geometric shapes may be selected arbitrarily.

Smoothing the transitions between the subregions of the at least two images with different exposure time results in smoother transitions between the subregions and thus a more uniform overall image. In this case, different ^¬ Liche smoothing methods can be used, which allow the transition between the partial regions of the images having different exposure times according to extend, and the impression of a single image and not the composition is brought several ^¬ rer images.

While recording at least two images a Be ^¬ lighting can be activated. By such lighting, the image quality can be further increased. In the case of arc processes, red-light illumination in particular has proven to be particularly suitable since an arc radiates little power in this wavelength range. The lighting can be permanently activated or controlled synchronously with the shutter speed of the camera. As illumination entspre ^¬ sponding light emitting diodes or arrays may be a plurality of light emitting diodes used that can be arranged because of the small size simply ne ^¬ ben or near the camera to the burner.

During the recording of at least two images with different exposure time ^¬ Licher various filters can be applied. Through such filters, in particular gray value filters, the quality of the images, in particular those with a short ^exposure time, can be further increased. Particularly suitable are switchable filters, which may be formed for example by appropriate liquid crystals.

An offset between the at least two consecutively recorded images with different exposure time can be corrected when displaying the images on the display device. In particular, during rapid movements of the burner along the processing path, such a correction of the offset between two consecutively recorded images for a high-quality overall image can prove or prove necessary. The correction is effected by software by means of a corresponding image processing before the display of the images on the display device.

The refresh rate is preferably selected between 10 Hz and 100 Hz. Such values have been mentioned as preferred ^¬.

In addition to the images or partial images, certain process parameters can also be displayed. Such process parameters may provide the user with further interesting information about the arc process. For example, at a

Welding process the welding current used, the Drahtvorschubge ^¬ speed and the like. displayed on the display ^¬ who.

The inclusion of at least two images with different Be ^¬ exposure time can be synchronized with the arc process ^¬ the order still to be able to achieve better results. A

Such synchronization of the recordings of the at least two images with different exposure times is particularly useful in processes, in which the arc is temporarily removed by a short circuit, such as a short-circuited ^¬ welding process. Thus, the images can be taken at times when no or only a light arc is burning, whereby the image quality can be improved due to the lack of a bright arc. For example, the voltage signal can be used in a welding process for triggering the image recordings. In this way, a representation could take place in which the arc is quasi hidden by pictures are taken only at times when no arc burns.

The at least two images with different exposure times, the portions of these images and or or composed of the Teilbe ^¬ rich images possibly together with product Measurement parameters can be saved for later use. For example, after an arc process, the stored data may be processed for quality analysis or for documentation purposes.

Alternatively, or in addition to storing the at least two images with different exposure times, the Teilbe ^¬ rich these images and or or to ^¬ from the partial areas sammengesetzten images can be transmitted in any case together with process parameters as well as to certain destination addresses. In this way, the data obtained during the arc process to remote destinations, such as a welding center, transferred and processed there.

The object according to the invention is also achieved by an above-mentioned device for monitoring an arc process, in which the control device for cutting out subregions of the at least two images with different exposure time and for combining the subregions into a composite image, and the display device for displaying the composite image is trained. A derarti ^¬ ge device is relatively simply with standard and

inexpensive cameras and a corresponding control device feasible. For the achievable advantages, reference is made to the above description of the method. When Rea ^¬ capitalization of the controller by a microcontroller the necessary actions with appropriate PROGRAMMING ^¬ tion of the microcontroller are relatively easy to implement.

The monitoring system may include lighting. As already mentioned above, lighting in the red wavelength range is particularly suitable. Red light emitting light ^¬ diodes are available with relatively high light output with a small size.

The lighting can be formed, for example, by an array of light emitting diodes. Such an array of, for example, light-emitting diodes can be arranged next to or around the optics of the camera of the monitoring system. Before the at least one camera, a preferably switchable filter can be arranged. Various technologies, such as liquid crystals, can be used.

For documentation purposes or later analyzes, a memory for storing the at least two images with different exposure time, the subregions of these images and / or the images composed of the subregions may possibly be provided together with process parameters.

To forward the information to remote evaluation or the like. can be at most provided together with process parameters comprises means for transmitting the at least two images with different exposure times, the portions of these images and or or the composite part from the preparation ^¬ chen images.

The invention will be explained in more detail with reference to the accompanying drawings. Show:

Figure 1 is a schematic schematic diagram of a burner for ^¬ leadership of an arc process with a device for monitoring the arc process.

Figure 2 is a schematic diagram of the in-housed Lichbogenprozess ^¬ nen and displayed images according to a variant embodiment. and

3 shows a flowchart for illustrating a variant of the method according to the invention.

1 shows a schematic schematic diagram of a burner 1 for performing an arc process, in particular a welding torch for carrying out a welding process, with a device for monitoring the arc process. Between the burner 1 and the workpiece to be machined (not shown), an arc 2 is ignited and bridged by means of a material supplied via a welding wire, a gap between two workpieces or the surface of the workpiece coated. To control the arc process, a Monitoring system 3 may be arranged on the burner 1, which includes a camera 4 and possibly a lighting 5. Before Ka ^¬ mera 4 different filter 6 can be arranged to increase the Qua ^¬ formality of the captured images. The burner 1 is connected via a hose package 7 to the power source 8. A control means 9 of the monitoring system 3 serves to ent ^¬ speaking control of the camera 4. According to the invention, the control means 9 is formed to cooperate with the camera 4 to ^¬ least two images P _{± j} depending refresh rate f _B with different exposure times t _Bj receive in succession, and these at least show two images P _{± j} with different exposure time t _Bj on the display device 10. ^¬ advantageous way be enough, from the captured images P _{± j}

different exposure time t _Bj sections P ' _{± j} cut out ^¬ and summarized into a composite image Ρ'Ί, as will be described in more detail with reference to the following figures 3 and 4.

The control device 9 can be provided with a memory 11 for storing the at least two images P _{± j} with different exposure time t _Bj , the partial areas P ' _{± j of} these images P _{± j} and / or the images zusammen' composed of the partial areas P ' _{± j} . Ί, if necessary together with process parameters of the arc process, be connected. Furthermore, a transmission device 12 can be provided, via which the relevant data, in particular the images P _{± j} with different exposure time t _Bj , the partial areas P ' _{± j of} these images P _{± j} , the images composed of the Teilbe ^¬ rich P' i _j images Ρ'Ί, possibly process parameters, can be transmitted to specific destinations. The

Transmission device 12 may in particular be formed by a corresponding interface to the World Wide Web or an internal ^database . In addition, an interface 13 can still be provided on the control device 9. A derarti ^¬ ge interface 13 an acoustic Einrich ^¬ tung example, can be controlled.

Fig. 2 shows a schematic diagram of the electric arc process taken on ^¬ and displayed images P _{± j} according to an embodiment of the invention. In this embodiment, the four images Pn to P ₁₄ with different exposure time t _B i to _B 4 further processed by certain sections P 'n to P' _{14 are cut} out of the images Pn to P ₁₄ and assembled into a composite image Ρ'Ί. For example, from the image Pn with the lowest exposure time t _B i, the portion P _'L1 in the center of the image P' n cut, which is located in the center of the arc with a particularly high intensity radiation ^¬. Due to the low exposure time t _B i, however, this area is also displayed optimally for the user. The immediate vicinity of the arc is n by a ent ^¬ speaking portion P _'12 of the image P' in the form of a quadra ^¬ tables frame with a slightly higher exposure time t _B 2 detected. Finally, it is cut out from the picture P ₁₄ with the maximum exposure time t _B 4, the portion P _'14 remote from the arc farthest. In the illustrated embodiment, the subregions are formed in the form of squares or square rings or frames. However, any variants of partial regions, for example circular surfaces or circular rings, are possible.

The subareas P 'n to P' ₁₄ are now combined to form a composite ^¬ th image Ρ'Ί and displayed on the display device 10. Thus, a single image representing sämtli ^¬ surface areas of the arc process optimal, namely, the center of the arc by the partial area P results _'L1 of the image Pii with the lowest exposure to the outer Randbe ^¬ rich, the through part P' ₁₄ of the image P _{14 is formed} with the largest exposure time t _B4 . The transitions between the subregions P ' _L1 to P' ₁₄ can also be smoothed accordingly so that a harmonic composite image Ί'Ί re ^¬ sultiert.

Finally, FIG. 3 shows a flowchart for illustrating a variant of the method according to the invention. When monitoring of the electric arc process in accordance with step 100, a first image Pn is provided with a first exposure time t _B i (step 101), then a second picture P ₁₂ with an exposure ^¬ time t _B2 (step 102), then a third image P ₁₃ with a Be ^¬ exposure time t _B3 (step 103), and finally a fourth image P ₁₄ with an exposure time t _B4 (step 104) was added. The images of the images P _{± j} with different exposure time t _Bj are repeated at the selected refresh rate f _B. Thus, the images P _{± j} can be recorded without interruption, as shown by the dashed line, so that essentially real-time processing can be realized. According to step 105, the recorded images Pn to P _{14 are} further processed and optionally stored, in particular from the images Pn to P ₁₄ corresponding sections P 'n to P' ₁₄ cut out ^¬ cut. The type of subregions may be predetermined or freely selectable by the user. The further processing of the images Pn to P ₁₄ can take place immediately after the acquisition of each individual image P _{± j} or else only after all the images Pn to P _{14 have been} taken. The further processing preferably takes place stepwise, ie after an image P _{± j has been} recorded. According to query 106, the selection is made as to whether smoothing (step 107) is to be performed or not. In the case of performing a smoothing, the transitions between the subregions P ' _L1 to P' _{14 of} the images Pn to P ₁₄ with different exposure time t _B i to t _B 4 are smoothed accordingly. According to step 108 the representation of the partial images formed by the in step 105, P 'ii to P' ₁₄ composite overall image Ρ'Ί carried out on the display device ^¬. With the selected refresh rate f _B is jumped back to the beginning of the process and started with the recording of the next images P _{± j} with different exposure times t _Bj . After completion of the arc process, the process according to step 109 is terminated. Accordingly, the partial images P _{'± j} are renewed with the refresh rate f _B, so resulting in a film for the observer in the overall image ^¬ Ρ'Ί.

The inventive method and the Vorrich ^¬ processing according to the invention enable an optimal representation of a Lichtbogenpro ^¬ zesses despite the high light intensity of the arc.

Claims

Claims:

1. A method for monitoring a performed with a burner (1) arc process, in particular welding process, wherein the burner (1) performs a movement along a processing path (x), and with the help of one with the burner (1) ver ^¬ bound, at least one Camera (4) comprehensive

Monitoring system (3) images (P _± ) of the vicinity of the arc (2) with a refresh rate (f _B ) are recorded and the images (P _± ) are displayed on a display device (10), wherein the refresh rate (f _B ) in a row at least two images (P _{± j} ) are recorded with different exposure time (t _Bj ), characterized in that cut out of each of the at least two images (P _{± j} ) with different exposure time (t _Bj ) partial areas (P ' _{± j} ) and to is shows ^¬ is a composite image are combined (Ρ'Ί), and at ^¬ sammengesetzte image (Ρ'Ί) on the display device (10).

2. The method according to claim 1, characterized in that the at least two images (P _{± j)} with an exposure time (t _{B j)} up ^¬ taken which is smaller than the Bildwiederholperiodendauer defined by the Bildwiederholfre ^acid sequence (f _B) (T _B = 1 / f _B ), preferably between 0.01 ms and 20 ms.

3. The method according to claim 1 or 2, characterized in that the partial regions (P ' _{± j} ) are formed by circular surfaces or circular rings.

4. The method according to any one of claims 1 to 3, characterized in that the transitions between the subregions (P ' _{± j} ) of the at least two images (P _{± j} ) with different exposure time (t _Bj ) are smoothed.

5. The method according to any one of claims 1 to 4, characterized in that during the recording of the at least two images (P _{± j} ), a lighting (5) is activated.

6. The method according to any one of claims 1 to 5, characterized in that during the recording of the at least two images (P _{± j} ) with different exposure time (t _Bj ) different filters (6) are applied.

7. The method according to any one of claims 1 to 6, characterized in that an offset (Ad) between the at least two successive ^¬ recorded images (P _{± j} ) with different exposure time (t _Bj ) when displaying the images (P _{± j} ) is corrected on the display ^¬ gevorrichtung (10).

8. The method according to any one of claims 1 to 7, characterized in that the image refresh rate (f _B ) is selected between 10 Hz and 100 Hz.

9. The method according to any one of claims 1 to 8, characterized in that in addition to the images (P _{± j} ) or sub-images (P'ij) process parameters are displayed.

10. The method according to any one of claims 1 to 9, characterized in that the recording of the at least two images (P _{± j} ) with different exposure time (t _Bj ) is synchronized with the arc process.

11. A method according to any one of claims 1 to 10, characterized in that the at least two images (P _{± j)} with differing ^¬ cher exposure time (t _{B j),} the partial regions (P'ij) of these images (P _± j), and respectively . or which consist of the partial regions (P'ij) together amount ^¬ translated images (Ρ'Ί) at best be stored together with process parameters.

12. The method according to any one of claims 1 to 11, characterized in that the at least two images (P _± j) with unterschiedli ^¬ cher exposure time (t _Bj ), the sub-areas (P'ij) of these images (Pij) and or or consisting of the partial regions (P'ij) together amount ^¬ translated images (Ρ'Ί) be at most transmitted together with process parameters.

13. An apparatus for carrying out a method for monitoring a performed with a movement along a processing path (x) burner (1) performed

Arc process, in particular welding process, after a of claims 1 to 12, with the burner (1) composites ^¬ NEN, at least one camera (4) comprehensive monitoring system (3) for producing images (P _±) around the arc (2) (with a refresh rate f _B ), a display device (10) for displaying the images (P _± ), and with a device (9) for controlling the monitoring system (3) for receiving at least two images (P _{± j} ) with the image refresh rate (f _B ) and different exposure time (t _Bj) one behind the other, as ^¬ characterized by that the control device (9) for cutting out portions (P _{'± j)} from the at least two images (Pi _j) with different exposure times (t _Bj) and to ^¬ summary of the sub-areas (P ' _{± j} ) to a composite image (Ρ'Ί), and the display device (10) for displaying the composite image (Ρ'Ί) is formed.

14. The device according to claim 13, characterized in that the monitoring system (3) comprises a lighting (5).

15. The apparatus according to claim 14, characterized in that the illumination (6) is formed by an array of light-emitting diodes.

16. Device according to one of claims 13 to 15, characterized in that in front of the at least one camera (4) a preferably ^¬ switchable filter (6) is arranged.

17. Device according to one of claims 13 to 16, characterized in that a memory (11) for storing the at least two images (P _{± j} ) with different exposure time (t _Bj ), the subregions (P ' _{± j} ) of these images ( P _{± j} ) and / or the composite of the sub-areas (P ' _{± j} ) images (Ρ'Ί) is possibly provided together with process parameters.

18. Device according to one of claims 13 to 17, characterized in that a device (12) for transmitting the at least two images (P _{± j} ) with different exposure time

(t _Bj ), the sub-areas (P ' _{± j} ) of these images (P _{± j} ) and / or the composite of the sub-areas (P' _{± j} ) images (Ρ'Ί) is possibly provided together with process parameters.