FI126900B

FI126900B - Procedure and arrangement for analyzing a property of a weld joint

Info

Publication number: FI126900B
Application number: FI20156027A
Authority: FI
Inventors: Perttu Sipilä; Kai Niiranen
Original assignee: Optiweld Oy
Priority date: 2015-12-29
Filing date: 2015-12-29
Publication date: 2017-07-31
Also published as: FI20156027A7; WO2017115015A1

Description

METHOD AND ARRANGEMENT FOR ANALYSING A PROPERTY OF A WELD SEAM

TECHNICAL FIELD OF THE INVENTION

The invention relates to a method and arrangement for analysing a property of a weld seam, such as a weld seam quality, cross-sectional profile, toughness, long-term sustainability or fatigue strength or opening angles, curvature, depth, full penetration, seam width, humping, or a degree of asymmetry during welding.

BACKGROUND OF THE INVENTION

Number of methods and techniques are known to analyse properties of a weld seam, such as visually estimating or scanning or imaging by laser or X-ray or other radiating devices. The laser scanner devices are typically based on triangulation measurement, where the weld seam is scanned over with a predefined frequency so that the measurement can be determined for later use. Also a CMOS camera imaging is used for determining of the weld seam dimensions and shapes. It is also known to use cameras to take images or video-radiographic images of the cross section of the weld joint and to compare its parameters to a predetermined shape of desired weld in order to provide estimation about the quality.

There are however some disadvantages relating to the known prior art. Even if the optical imaging systems are typically relatively fast and non-invasive, their accuracy and resolution is not good enough to be able to generate so accurate surface profile of the weld seam that to overall quality could be estimated and determined in a reliable way enough. In addition e.g. using shorter wavelengths, such as x-rays or gamma-rays is not often suitable for accurate surface profile, as well as also the health risk in these techniques is significant.

SUMMARY OF THE INVENTION

An object of the invention is to alleviate and eliminate the problems relating to the known prior art. Especially the object of the invention is to provide a system for analysing properties of a weld seam in a reliable way enough and to get so accurate surface profile of the weld seam that all of the important surface shapes related to the weld seam that makes possible to predict its long-term sustainability or fatigue strength from the profile parameters can be achieved.

The object of the invention can be achieved by the features of independent claims.

The invention relates to an arrangement for analysing a property of a weld seam according to claim 1. In addition the invention relates to a method for analysing a property of a weld seam according to claim 16, as well as to computer program product according to claim 17.

According to an embodiment of the invention at least one property of an weld seam is analysed by providing a spectre of electromagnetic radiation band to an object representing the weld seam so that different wavelengths of said radiation are focused to different depths in a direction of a normal of the object The object representing the weld seam is either the weld seam to be determined as such or alternatively a casting mould representing the weld seam, such as a silicone casting mould. According to the embodiment at least a wavelength focused on and reflected from the depth of the surface of said object is received and analysed. In analysing the wavelengths with intensities over a predetermined threshold value are selected, and one of which wavelength is then construed to represent the wavelength focused on and reflected from the depth of the surface of the object. The electromagnetic radiation band is advantageously continuous spectre and comprises ultraviolet spectral range, visible spectral range and/or infrared spectral range.

It is assumed that only the wavelengths reflected from the surface or some other point of the object are able to have intensity over the predetermined threshold value. In addition the wavelength travelled the shortest path is construed to represent the wavelength focused on and reflected from the depth of the surface of the object at a certain location to be determined. This is because no reliable wavelength can be reflected in the area between a device outputting said spectre of electromagnetic radiation band and the object (thus travelling more shorter path), and in other hand the wavelength travelled the longer path will represent wavelength either reflected behind or beyond the surface of the seam or having multiple reflections and being thus non-reliable.

Depending how the spectre is generated, so whether the shortest wavelengths are focused closer to the device and the longest behind the object or vice versa, the shortest or longest wavelength of said selected wavelengths determines the depth (or Z-coordinate) of the surface of the object at a certain point.

The length (or at least relative length) of the path of each wavelength can be deduced based on the wavelength, i.e. the colour of the wavelength, since the shortest and longest wavelengths of the radiation are focused to different depths so that the wavelength between the shortest and longest wavelengths is focused essentially to a depth of a median surface level of the object.

Additionally the spectre lines of the electromagnetic radiation band can be emitted so that a planar beam cone is provided of the wavelength and again to extend over the weld seam (or object) and further on at least two bodies (typically sheet or plates) to be welded by said weld seam. By providing a planar beam cone a cross-sectional profile can be better determined by one shot. In addition the planar beam cone is spread wider, a mutual disposition or placing, bending or alignment, such as linear or angular misalignment of the bodies to be welded can be determined based on the received wavelengths of the cone reflected from the bodies.

According to an embodiment the electromagnetic radiation, so typically at least partially visible light from the radiation source (advantageously not a point-like source, but with a circular emission), is divided to different wavelengths (colours), where each colour is focused to a certain own depth. Each colour is additionally spread and “extended” to a planar or line beam. As can be seen each colours are reflected, at least in principle, in a certain (own) direction (independently of each other wavelength), especially in the question of weld seam. The focused wavelength will be reflected at maximum intensity from a certain focus spot (on the surface of the object or weld seam) and non-focused will be reflected area located somewhere else that said objet or weld seam of interest. The receiving unit or detector is advantageously arranged (focused) to receive reflections reflected essentially and optimally from the profile cross-section. Because the non-focused wavelengths will be reflected from the area locating outside the area of the object or the weld seam, they will be reflected and passed by the side of the detector and additionally with smaller intensity than the beams focused on and reflected from the object or the weld seam. Again it might be that numbers of wavelengths focused outside the object or the weld seam (in addition to the desired wavelength focused on the object or the weld seam) may be received by the detector, whereupon the wavelength with the shortest path (top reflected) is selected.

According to embodiments of the invention a cross-sectional profile, comprising also joint or groove or notch areas, of the weld seam can be determined based on the determined depths. It is to be noted that when the spectre of electromagnetic radiation band (so the arrangement) and the object are moved in relation to each other, multiple images can be captured in real-time during moving and the longitudinal or overall profile or other properties along the length of the seam can be determined.

In addition it is to be noted that different exposure times can be used in order to achieve information from the points of the surface having e.g. different inclination angle in relation to the emitted spectre, namely with a first short exposure time a surface profile having front surface essentially perpendicular to the radiation beam will be exposed enough but the surface having inclined surface profile will be underexposed, and again with a second long exposure time the surface having inclined surface profile in relation to the radiation beam will be exposed enough but the surface profile having front surface essentially perpendicular will be overexposed. By combining these images a satisfactory result can be achieved so that the whole surface profile of the object is imaged accurate enough. Naturally number of different exposure times can be used.

The properties, such as cross-sectional profile or the like described in this document, can be determined by comparing measured parameter, such as geometric parameter, like a cross-section profile, to a predetermined corresponding parameter or to respective reference value or respective tolerance interval of a reference weld seam, such as to a cross-section profile the reference weld seam. In generally the measured parameters are compared to a predetermined statistical distribution, which represent the corresponding parameters. These predetermined corresponding parameters or statistical distribution data are advantageously stored into a memory means.

According to an embodiment controlling information is generated to a weld seam manipulating device based on the measured parameters, in order to control the weld seam manipulating device to produce the weld seam so that the quality parameters correspond and match with a certain tolerance to the predetermined reference weld seam parameters. The controlling information can also be used for indicating the determined quality parameters to the user, such as especially indicating if the determined quality parameters does not fulfil the required level. The indication may be implemented e.g. by sound, visually and/or via tactile feedback, for example.

According to an embodiment the weld seam manipulating welding device is a welding device e.g. in a laser welding process, whereupon the controlling information is data used to controlling welding parameters of the welding device, such as current, length of arc, angle, position or speed, or even ON/OFF -type information to stop or start the welding process. By controlling the welding process by the welding parameters the welding device is advantageously controlled to produce the weld seam so that properties of the weld seams, such as cross-sectional profile, opening angles, curvature, depth, full penetration, seam width, humping, and a degree of asymmetry during welding among other, correspond and match with a certain tolerance to the predetermined reference weld seam parameters.

According to an embodiment the weld seam manipulating welding device is a marking or painting device, and wherein the generated controlling information is information used to control the marking or painting device to mark or paint a certain point of the weld seam if a certain parameter of said weld seam at said certain point does not correspond or match respective reference values or respective tolerance intervals of a reference weld seam.

According to an embodiment the weld seam manipulating welding device is a sanding machine and wherein the generated controlling information is information to control said sanding machine to sand or polish a certain point of the weld seam if a certain parameter of said weld seam at said certain point does not correspond or match respective reference values or respective tolerance intervals of a reference weld seam.

The seam quality might be assessed as unsatisfactory for example if the geometric parameter determined does not correspond to a respective reference value or lies outside of a respective tolerance interval.

The method of the embodiments can be implemented by a handheld device or arrangement, or an arrangement being integrated into a production line (on-line installation) or being a portion of a welding arrangement. In addition at least some of the steps to implement the embodiments, such as especially for analysing the properties of the weld seam, can be implemented by running a computer program product on a data processing means. The computer program product code may be stored in a media run on the data processing means, or it may be stored into data cloud system. In addition the computer program product can be used, when run, to provide the control information to weld seam manipulating welding device. In addition the measured data can also be stored into the memory, e.g. to the cloud system, for possible later use or quality inspection purposes.

According to an exemplary implementation some embodiments of the invention can be implemented by a LCI (Lateral Chromatic Imaging) device which produces at least one light line (planar beam) over the weld seam. The LCI device is capable of creating an accurate line image of the cross section of the weld seam. Thus the three-dimensional course of the weld seam can be accurately detected and its geometrical data measured. Especially e.g. groove or notch in front of the weld seam can be seen and measured and the parameters of its shape can be determined, such as opening angles, curvature, depth, width etc. These are one of the most important parameters with which makes possible to accurately estimate the quality of the weld seam, such as toughness, long-term sustainability, fatigue strength or the like. The LCI device can be advantageously moved along the weld seam and similarly taking multiple images in real-time. These images can be transferred to a processing device, which analyses those using specified algorithms and gives an estimation of the weld seam quality. This result can be transferred to the welding robot or available to a person and thereby adjust the weld seam quality even during the welding process.

The present invention offers advantages over the known prior art, such as the possibility to measure very accurately the whole profile of the seam, also the groove or notch areas. For example LCI technology enables to have pm (micrometer) resolution image over the whole weld seam and all of its noteworthy surface shapes relating to it. Furthermore the embodiment of the invention also enables imaging a butt joint and T-connected parts (T-joints) because of its imaging technology, accuracy and mechanical size. The embodiments of the invention are also not sensitive to imaged weld seam vibration during measurement. In addition the invention enables measuring, analysing and feedback to the system in real time. Having this accurate image and fast analyse enables higher quality examination of the weld seam than before. Moreover the measurement and determination can be done in real-time which allows to produce feedback information to the welding system, for example, to adjust the welding parameters and therefore achieve higher quality weld seam.

BRIEF DESCRIPTION OF THE DRAWINGS

Next the invention will be described in greater detail with reference to exemplary embodiments in accordance with the accompanying drawings, in which:

Figure 1 illustrates a principle of an exemplary arrangement for analysing a property of a weld seam (side view) according to an advantageous embodiment of the invention,

Figure 2 illustrates an exemplary arrangement for analysing a property of a weld seam (front view) according to an advantageous embodiment of the invention, and

Figure 3 illustrates an exemplary arrangement for analysing a property of a weld seam of t-connected parts (front view) according to an advantageous embodiment of the invention.

DETAILED DESCRIPTION

Figure 1 illustrates a principle of an exemplary arrangement 100 for analysing properties of a weld seam 101 (side view) according to an advantageous embodiment of the invention, wherein the arrangement 100 comprises an optical component 102, such as a prism, lens or optical lattice, for providing a spectre 103 of electromagnetic radiation band to the weld seam 101. The spectre 103 is spread so that different wavelengths 103A, 103B, 103C of the radiation are focused to different depths l^, h2, h3 in a direction of a normal 104 of the weld 101. In addition the arrangement comprises also a receiving component 105 for receiving at least a wavelength 106B focused on and reflected from the depth h2 (level) of the surface of the weld seam 101 at a certain point of the weld seam. The receiving component comprises 105 a detector, such as a line detector, CCD device, or an imaging spectrometer. One example is e.g. a 2048x1088 matrix detector. The arrangement may also comprise a source 111 for generating the electromagnetic radiation band, such as a laser source.

Moreover the arrangement comprises also an analysing unit 107 for analysing the received wavelengths 106A, 106B, 106C and to select wavelengths having intensity over a predetermined threshold value. The analysing unit 107 is also configured to construe the wavelength travelled the shortest path to represent the wavelength 106B focused on and reflected from the depth h2 of the surface of the weld seam 101 and thereby configured to determine the depth h2 of the weld seam at said certain point of the weld seam.

The arrangement 100 may also provide, advantageously using the optical emitting components, the spectre lines 103 of said electromagnetic radiation band so that a planar line or beam 108 of each wavelength extend over the weld seam (see Fig 2, a front view) at a certain point in a direction of a cross axis line 109, which is perpendicular both to the normal 104 and longitudinal direction 110 of the weld seam.

In addition the arrangement is additionally configured to receive the reflections of the planar line or beam wavelengths 106A, 106B, 106C focused on and reflected from the different depths hi, h2, h3 of the surface of the weld seam along the cross axis line 109. The arrangement is also configured to determine a cross-sectional profile (see the front view in Fig. 2) of the weld seam 101 at said certain point along of the elongated weld seam.

According to an embodiment the arrangement may also comprise, or is configured to communicate 113 with a welding device 112, whereupon the arrangement is configured provide controlling information to control the welding device 112 to produce the weld seam so that the parameters correspond and match with a certain accuracy to the predetermined reference weld seam parameters. It is to be noted that even if the welding device 112 is depicted as an example, the device 112 can be also other weld seam manipulating device controlled by the arrangement, as is disclosed elsewhere in this document.

Figure 3 illustrates an exemplary arrangement for analysing a property of a weld seam 101 of t-connected parts (front view) according to an advantageous embodiment of the invention.

The invention has been explained above with reference to the aforementioned embodiments, and several advantages of the invention have been demonstrated. It is clear that the invention is not only restricted to these embodiments, but comprises all possible embodiments within the spirit and scope of the inventive thought and the following patent claims. In particularly it is to be noted that even if the determination of the physical weld seam is depicted in Figures, the arrangement and method of the embodiments according to the invention can also be used to analyse and determine a mould of the seam weld, such as a silicon casting mould.

Claims

An arrangement (100) for analyzing a property of a weld (101) comprising: an optical component (102) for delivering an electromagnetic radiation band spectrum (103) to a target representative of said weld (101) such that different wavelengths (103A, 103B, 103C) of said radiation ) focusing on different depths (h-ι, h2, h3) in the normal (104) direction of said object representing said weld, - a receiving component (105) configured to receive at least a wavelength (106B) focused on said weld (101) said object surface depth (h2) and reflected therefrom at a particular point of the seam, characterized in that the arrangement further comprises an analyzing unit (107) configured to analyze said received wavelengths (106A, 106B, 106C) and select a wave of a predetermined intensity and Interpret the shortest track passing n wavelength means wavelength (106B) focused and reflected from the surface depth (h2) of said object representing said weld seam (101), and thus configured to define said weld seam depth (h2) at said particular position of the weld, and exposure time, wherein said first exposure time is shorter than said second to provide information about surface points having a different slope relative to the emitted spectrum (103).

The arrangement of claim 1, wherein the arrangement is further configured to provide spectral lines (103) of said electromagnetic radiation band such that the planar beam (108) covers wavelengths in the direction of the transverse line (109) of the object representing said welding seam (103). 104) that with respect to the longitudinal direction (110) of said weld, the arrangement is further configured to receive wavelengths (106A, 106B, 106C) focused on and reflected at different depths (h-ι, h2, h3) of the surface of said object representing said weld, 109), and thus configured to determine the cross-sectional profile of said weld seam (101) at said particular point of the seam.

An arrangement according to any one of the preceding claims, wherein said arrangement is also configured to define a cross sectional profile of said weld including a joint, groove or notch along a longitudinal direction (110) of said weld based on said specific depths (h-ι, h2, h2) of said weld. at different points.

An arrangement according to any one of the preceding claims, wherein said object representing said welding seam is an actual physical welding seam (101) or a casting mold, such as a silicone casting mold, representing said welding seam (101).

An arrangement according to any one of the preceding claims, wherein the arrangement also comprises a source (111) for generating said electromagnetic radiation band, and wherein said electromagnetic radiation band is a continuous spectrum and comprises an ultraviolet spectral region, a visible spectral region and / or an infrared spectral region.

An arrangement according to any one of the preceding claims, wherein the optical component comprises a prism, an optical lattice and / or lenses for spreading the electromagnetic radiation band into said spectrum and / or planar beam.

An arrangement according to any one of the preceding claims, wherein the receiving component comprises a detector, such as a line detector, a CCD device or an imaging spectrometer.

An arrangement according to any one of the preceding claims, wherein the arrangement (100, 107) is configured to determine weld quality, toughness, long-term fatigue strength by comparing parameters of a defined cross-section profile to predetermined cross-section profile or equivalent reference values of a reference weld.

An arrangement according to claim 8, wherein the parameters used to determine the quality of said weld are selected from the group consisting of: opening angles, curvature, depth, full penetration, weld width, humping phenomenon, cross section profile and degree of asymmetry during welding.

An arrangement according to any one of the preceding claims, wherein the arrangement (100, 107) is configured to generate control information on the welding joint manipulator (112) for producing the welding joint (101) so that its parameters match and match a predetermined parameter with a certain tolerance.

An arrangement according to claim 10, wherein said welding joint manipulation device is - a welding device (112) and wherein the generated control information is information for controlling welding parameters of said welding device to produce a welding joint (101) such that its parameters match and match a predetermined parameter - or a coloring device and wherein the generated control information is information for directing said marking or coloring device to mark or color a particular point of the weld where the particular parameter of said weld does not match or match the corresponding reference values or generator tolerances of the reference weld, and control information is information for guiding said grinder to grind or rub a particular spot of a weld in the event that said welding seam given parameter is said certain point corresponds to or matches the corresponding comparison with the reference values of the welding seam or the respective tolerance intervals.

An arrangement according to any one of the preceding claims, wherein the welding seam is a welding seam and wherein the arrangement also comprises a welding device (112) and wherein said arrangement is configured to control the welding device (112) with control information according to claim 10 to obtain a welding seam having cross-section of the reference weld with a predefined reference parameter comprising a reference profile.

An arrangement according to any one of the preceding claims, wherein the arrangement is further configured to emit spectral lines (103) of said electromagnetic radiation band such that the planar beam (108) of wavelengths covers an elongate weld (101) and further at least two bodies to be welded by said weld. , 107) is configured to determine the relative position, deflection, or alignment of said at least two bodies, such as linear or angular misalignment, based on the received wavelengths of the cone reflected from said at least two media.

An arrangement according to any one of the preceding claims, wherein the arrangement is configured to move relative to the object representing said weld and to take a plurality of real-time images during movement.

An arrangement according to any one of the preceding claims, wherein the arrangement is a handheld device or an integral part of a welding arrangement.

A method for analyzing a property of a weld (101) comprising the steps of: - providing (102) a spectrum (103) of electromagnetic radiation to a target representative of said weld (101) such that different wavelengths of said radiation are focused at different depths (h-ι); h2, h3) in the direction of the normal (104) of said object representing said weld, - receiving (105) at least a wavelength (106B) focused on the surface depth (h2) of said object representing said weld (101) at a particular point of the elongated weld; characterized by: - analyzing (107) said received wavelengths (106A, 106B, 105C) and selecting wavelengths above a predetermined intensity and interpreting said wavelength of one of the shortest orbits of said shortest orbit to be the wavelength of said target a wavelength (106B) focused and reflected to a depth (h2), and thus defining a depth (h2) of said weld at said particular point in the weld, and - using first and second exposure times, said first exposure time being shorter than said second exposure point having a different inclination relative to the emitted spectrum (103).

A computer program product adapted to perform at least the analysis steps of method claim 16 when running said computer program product on a data processing device for analyzing a property of a weld (101).

The computer program product according to claim 17, wherein said computer program product is further adapted to provide control information to a weld joint manipulator (112), such as a welding device (112), based on said analysis to control welding parameters of said welding device to produce a weld seam (101) a reference weld with predefined reference parameters.