KR102235832B1 - Portable type welding inspection appatatus and inspection method - Google Patents

Abstract

A portable welding defect inspection apparatus and inspection method are disclosed.
Among them, the inspection device includes a housing; A laser vision sensor installed in the housing and including a laser light source for scanning two or more laser beams on a welding surface of a workpiece, and an image camera for obtaining a profile of a weld bead by detecting the laser light scanned on the welding surface; And a standard data storage unit in which standard welding condition information for welding process, joint shape, wire feeder speed, welding current, welding voltage, and welding speed, and standard dimension information of the welding unit are stored. A profile storage unit for receiving the image of the welding bead obtained from the image camera of the laser vision sensor unit, processing the image, and converting the image into a digital profile and storing it; A dimension calculation unit that calculates a cross-sectional dimension of a weld bead of a profile stored in the profile storage unit; A control module comprising; a control module comprising; a defect determination unit configured to determine whether the welding bead is defective by comparing the welding condition information and standard dimension information of the data storage unit with the cross-sectional dimension information calculated by the dimension calculation unit. _{The dimension factor calculated by the negative is the distance L 1} between the left bead point and the right bead point of the weld bead; _{A distance L 2} between the L ₁ and the vertices of the semicircular weld bead; _{A distance L 3} between the bead point on the left side of the weld bead and the straight line of the lower base material; The area A of the weld bead on the L _{1; An angle θ 1} between a straight line of the lower base material and a straight line of a weld bead 2 mm away from the straight line of the lower base material; It characterized in that it further comprises an angle θ ₂ ; between the straight line of the lower base material and the L _1.

Description

Portable type welding inspection appatatus and inspection method}

The present invention is for inspecting welding quality for fillet welds that are welded along the boundary of a round member such as a nut, and more particularly, detection of a weld bead based on profile data acquired by a laser vision sensor, and The present invention relates to a portable type welding defect inspection device and inspection method that is equipped with all functions capable of precisely performing inspection for major welding defects required in actual production sites and is easy to carry.

Welding is widely used as a method of joining metal materials because it simplifies the structure by naturally making the joint shape of the structure, provides homogeneous and high strength, and at the same time is inexpensive.

However, in general, the welded part and the metal in the vicinity thereof change the internal structure of the metal due to a rapid temperature change within a short time, resulting in brittleness, residual stress, pores, etc., and in many cases accompanied by various cracks. This may weaken the joint performance of the welding material, failing to satisfy the joint properties required for the welded structure, and may cause destruction of the weld joint.

As described above, various defects that appear to be unsatisfactory in appearance or performance occurring in the welding portion are referred to as welding defects, and prevention of welding defects is also the most difficult part in welding technology.

On the other hand, the degree of occurrence of welding defects increases as the strength of the material increases. Therefore, in order to secure the stability of the structure, a sufficient review is required at each stage of selection, design, construction, and inspection of materials that can suppress the occurrence of defects as much as possible during welding.

As an inspection method for welding defects, non-destructive inspection methods include RT (Radiographic Testing), UT (Ultrasonic Testing), MT (Magnetic Testing), PT (Penetrant Testing), and ET (Eddy Current Testing). Of the above methods, RT and UT are used for internal inspection and the rest are used for external inspection. These inspection methods must be equipped with a high level of inspection technology capability and auxiliary equipment, and in particular, the external inspection methods are inconvenient to make a suitability/nonconformity determination with the naked eye.

In general, as a method of determining defects outside of welding, a method of determining defects after obtaining 2D information of a welding part through a CCD camera, undergoing an image processing process, and calibrating it in 3D has been mainly used.

Barnett et al. acquired a two-dimensional image using a CCD camera in "laser guidance system for robot (Robotics welding, springer-Verlag, 1987)" and measured the intensity of the cross-section and longitudinal section of the ripple of the welding bead. A technique for determining weldability by calculation was disclosed. Here, the integral value and standard deviation of the pixel intensity were obtained using the brightness of the cross-sectional pixel, and the weldability of the bead was judged by judging that it was good welding when it had a dense and regular ripple.

In addition, Soudronic of Switzerland projects 5 lasers at a time using the laser vision sensor MVS-10 to determine the shape of the welded part of the tailored blank welding, and after acquiring and image processing a 2D image with a CCD camera. The weld defect was determined by calculating seam concavity, seam convexity, misalignment, bead width, and lack of penetration.

However, since the conventional laser vision sensor has a low speed, there is a problem that it cannot be used in a process that requires a high processing speed. Moreover, the conventional technologies simply measure the size of the bead of the welding part using a laser vision sensor, or only present the technology of tracking the welding line, and it is pointed out that the development of an algorithm to find the bead of the welding part or detect the appearance defect of the welding part is insufficient. There was this.

Document 1: Registered Patent Publication No. 10-1-26720 Document 2: Unexamined Patent Publication No. 10-2013-0038001

The present invention provides an all-in-one type portable welding quality inspection device capable of detecting welding beads and inspecting major welding defects required at an actual production site based on profile data acquired by a laser vision sensor. Is in.

In addition, the present invention is to provide an inspection method using the portable type welding quality inspection device.

The technical problem to be achieved by the present invention is not limited to the technical problems mentioned above, and other technical problems that are not mentioned can be clearly understood by those of ordinary skill in the technical field to which the present invention belongs from the following description. There will be.

According to an embodiment of the present invention for achieving the above technical problem, the housing; A laser vision sensor installed in the housing and including a laser light source for scanning two or more laser beams on a welding surface of a workpiece, and an image camera for obtaining a profile of a weld bead by detecting the laser light scanned on the welding surface; And a standard data storage unit in which standard welding condition information for welding process, joint shape, wire feeder speed, welding current, welding voltage, and welding speed, and standard dimension information of the welding unit are stored. A profile storage unit for receiving the image of the welding bead obtained from the image camera of the laser vision sensor unit, processing the image, and converting the image into a digital profile and storing it; A dimension calculation unit that calculates a cross-sectional dimension of a weld bead of a profile stored in the profile storage unit; A control module comprising; a control module comprising; a defect determination unit configured to determine whether the welding bead is defective by comparing the welding condition information and standard dimension information of the data storage unit with the cross-sectional dimension information calculated by the dimension calculation unit. _{The dimension factor calculated by the negative is the distance L 1} between the left bead point and the right bead point of the weld bead; _{A distance L 2} between the L ₁ and the vertices of the semicircular weld bead; _{A distance L 3} between the bead point on the left side of the weld bead and the straight line of the lower base material; The area A of the weld bead on the L _{1; An angle θ 1} between a straight line of the lower base material and a straight line of a weld bead 2 mm away from the straight line of the lower base material; An angle θ ₂ between the straight line of the lower base material and the L ₁ ; is provided with a portable welding quality inspection apparatus further comprising.

Preferably, it may further include a display unit provided on one side of the housing and outputting together the length, penetration, and tensile strength values of the weld bead calculated by the dimension calculating unit, and the determination result determined by the failure determination unit. have.

Preferably, it may further include a charging module provided inside the housing to supply power to the inspection device.

Preferably, the control module may further include an orthogonal projection calculating unit that calculates a slope from two or more profiles obtained by two or more laser light sources, and calculates an orthogonal projection from the slope value.

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According to another embodiment of the present invention, there is provided a welding quality inspection method using the portable welding quality inspection apparatus described above, wherein the welding quality inspection method includes receiving an image from the laser vision sensor, and a profile storage unit of the control module By doing so, it may include performing image processing including grabbing, filtering, thresholding, thinning, and profiling of the weld bead.

Preferably, it may further include calculating range data after the profiling step.

According to an embodiment of the present invention, it is possible to quantitatively provide information on the shape of the weld bead and whether or not there is a defect, thereby increasing the reliability of inspection of the weld bead, and providing visual feedback on whether the bead is defective or not, the bead defect in the production line. Can respond quickly.

In addition, according to an embodiment of the present invention, since image processing of 100 frames or more per second is possible, it can be effectively applied to an actual production line, thereby contributing to productivity improvement. Furthermore, when the inspection result is online, welding defects are determined in real time. There is an advantage that it is possible to find defective products and perform reinforcement welding for those defects immediately.

In addition, according to an exemplary embodiment of the present invention, all functions are integrated in a housing to be configured in a portable type, so that an operator can selectively inspect beads that need to be inspected while carrying them, thereby improving inspection efficiency.

These effects of the present invention are not limited to the above effects, and should be understood to include all effects that can be deduced from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a schematic configuration diagram of another inspection apparatus according to the present invention.
2 is a block diagram illustrating a configuration of a control module.
3A, 3B, and 3C are diagrams illustrating a method of image processing using a laser vision sensor according to an embodiment of the present invention.
4A and 4B are diagrams for explaining feature extraction of a weld bead, FIG. 4A is a diagram for detecting a straight line of a base material, and FIG. 4B is a diagram for detecting a measurement element of a weld bead.
5 is an input layer of welding information and welding part shape information.
6 is a diagram illustrating a method for obtaining an orthogonal projection (vertical section).
7 is a graph of the error rate of each length, penetration and strength prediction.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art may easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary. In addition, terms such as "unit", "group", and "module" described in the specification mean a unit that processes at least one function or operation, which can be implemented by hardware or software, or a combination of hardware and software.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a schematic configuration diagram of an inspection apparatus according to the present invention, FIG. 2 is a block diagram for explaining the configuration of a control module, and FIGS. 3A and 3B are views for explaining feature extraction of a welding bead, and FIG. 3 A, b, and c are diagrams showing a method of image processing using a laser vision sensor according to an embodiment of the present invention, and FIGS. 4a and 4b are views for explaining feature extraction of a weld bead, and FIG. 4a is a base material 4B is a diagram for detecting a measurement element of a weld bead, FIG. 5 is an input layer of welding information and weld shape information, and FIG. 6 is a diagram for obtaining an orthogonal projection (vertical cross section of the bead). It is a figure explaining the method, and FIG. 7 is a graph of the error rate of each length, penetration, and strength prediction.

As shown in the above drawing, the portable type welding defect inspection apparatus (hereinafter abbreviated as'inspection apparatus') 100 according to the present invention is composed of a housing 110, a laser vision sensor 120, and a control module 130. I can.

As the inspection device 100 has a built-in laser vision sensor 120 and a control module 130 in the housing 110 and has an integrated structure, it is easy to measure while moving the welding bead of various objects as well as carrying and storing it. It is possible to implement a portable type inspection device that can be used.

The laser vision sensor 120 includes a laser light source 123 that scans two or more laser beams on a welding surface of a workpiece, and an image camera 121 that detects laser light scanned on the welding surface to obtain a profile of a welding bead. ) Can be included. Preferably, the laser vision sensor 120 according to the present invention may be applied with a laser structured light and a high-precision 3D vision camera.

The above-described laser vision sensor obtains a height profile and an image using a laser triangulation (laser triangulation) technique. The laser line is projected onto the weld bead and the sensor image so produced is interpreted by the camera core and converted into a single height profile. Preferably, the image camera 121 may be provided with a ring-shaped ring light 122 around its tip in order to obtain a clear and bright image.

The control module 130 detects the dimensions of the profile transmitted from the laser vision sensor 120 and determines whether the bead welding is defective by comparing it with standard data. Standard welding condition information about (joint geometry), wire feed speed, welding current, welding voltage, welding speed, and standard dimension information of the welding part are stored. It may include a standard data storage unit 131. The standard data storage unit 131 stores standard values of welding conditions and welding dimensions, and serves as a reference value of the measured welding dimensions.

In addition, the control module 130 receives the image of the welding bead obtained from the image camera 121 of the laser vision sensor 120, converts the image into a digital profile and stores the image processing 132 It may further include.

Here, the image processing process includes filtering, binarization, thinning, and profiling of the image grabbed while the current image is being grabbed. It is to be done at the same time.

That is, as shown in FIG. 1, since the image transmitted from the laser vision sensor 120 contains a lot of noise, a simple low pad filter can be implemented using an average micro filter to remove this. As a result, discontinuous noise can be removed and noise in the vertical direction can be reduced, and filtering and binarization can be performed at the same time. Binarization is an operation of making an image that has passed the filter into only two values, 0 (black) if the value of each pixel is less than the threshold value, and 1 (white) if it is greater than the threshold value. It shows the image when it is completed.

In the thinning process, elements such as erosion, which take a long time, are removed by simplifying the existing thinning process, and it is configured to determine as a line with the thickness of the area selected in the binarization step.

In the profiling, the shortest path between the points at both ends determined as the step of determining the actual line and the noise is determined as the actual line. At this time, it is assumed that the noise component is generated at a distance from the actual line, and the horizontal (x) axis is equally spaced. Fig. 4(c) shows a feature line extraction image completed through a thinning step and a profiling step as described above. The black line in the middle is the feature line.

The boundary line detection algorithm is used for feature line extraction. In general, the boundary line detection algorithm performs a matrix operation using a 3×3 mask on the entire image, so the operation speed is considerably slow. However, since the binarized image is in the form of a simple image, the characteristic line can be found by connecting the central part in the detection part of the laser structured light continuous in the horizontal direction. This method can only be used for images with a single line image, such as laser structured light.

Here, the image processing operation may include a process of selectively calculating distance data. When the position in the image is known from the optical component of the laser vision sensor 120, the actual height can be calculated inversely. Through the actual distance data obtained in this way, the cross section of the three-dimensional shape of the weld bead is acquired.

In addition, the control module 130 may further include a dimension calculation unit 133 that calculates a vertical cross-sectional dimension of a weld bead of a profile stored in the profile storage unit 132.

_{The dimension factor calculated by the dimension calculation unit 133 is a distance L 1} between the left bead point 3 and the right bead point 4 of the welding bead, as shown in FIG. 4B; _{A distance L 2} between the L ₁ and the apex P of the semicircular weld bead; _{A distance L 3} between the bead point on the left side of the weld bead and a straight line of the lower base material; The area A of the weld bead on the L _{1; An angle θ 1} between a straight line of the lower base material and a straight line of a weld bead 2 mm away from the straight line of the lower base material; An angle θ ₂ between the straight line of the lower base material and the L ₁ ; Etc.

The left bead point 1 and the right bead point 2 of the welding bead detect straight lines 1 and 2 of the base material on both sides of the welding bead, as shown in FIG. 4A, and the end points of the straight lines 1 and 2 toward the welding bead And the left point in the drawing is defined as the left bead point, and the right point in the drawing is defined as the right bead point.

For reference, the _{area A of the welding bead on L 1} can be obtained by Equation 1 below.

Here, Δx is an interval between data in the weld bead area, and is 0.05.

k is the total number of data in the weld bead area.

When x=k, the z value is f(x _k ).

When all of the above unknowns are obtained as described above, the length of the weld bead, penetration, and tensile strength thereof are obtained.

In addition, the control module 130 further includes a defect determination unit 134 for finally determining whether a welding bead is defective, and the defect determination unit 134 is a welding condition of the standard data storage unit 131 By comparing the information and standard dimension information with the cross-sectional dimension information calculated by the dimension calculating unit, it is finally determined whether the welding bead is defective, and the result value is output (see FIG. 5).

In addition, the control module 130 calculates a slope (θ) from two or more profiles obtained by two or more laser light sources, as shown in FIG. 6, and calculates an orthogonal projection (vertical cross section) from the slope value. A portion 135 may be further included.

On the other hand, the inspection apparatus 100 according to the present invention is provided on one side of the housing, the angle length, penetration, and tensile strength values of the weld bead calculated by the dimension calculation unit 133, and the defect determination unit 134 The display unit 111 may be further included to output the determination result determined in FIG.

In addition, the inspection apparatus 100 according to the present invention may further include a charging module 140 provided inside the housing 110. The charging module 140 has an advantage that it can operate without using an external power source by providing power to the inspection device 100. Here, the housing 110 may be provided with a USB port for supplying external commercial power to the charging module 140 incorporated therein.

In addition, since the inspection device 100 according to the present invention measures the welding bead in a state possessed by the operator, the measurement position is not constant, so the photographing angle of the camera 121 is measured and the measured value is measured by the control module ( 130) may further include a gyro sensor (not shown), in particular, a 6-axis gyro sensor.

7 is a graph showing the results of calculating the length, penetration, and strength. As shown in this graph, as a result of verifying the result value calculated by the control module (), the calculation average error of each length is 0.103mm and 2.54%, The average error of calculation of penetration is 0.051mm and 9.87%, and the average error of calculation of strength is 27.379 Mpa and 9.689%. From this, it can be seen that the calculation error rate of this device is remarkably low.

As described above, the portable welding defect inspection apparatus according to the present invention can provide a reliable bead inspection method by being able to quantitatively provide information on the shape of the bead and whether or not there is a defect at high speed. By visually showing, it is possible to implement welding that can compensate for bead defects.

In addition, according to the present invention, since image processing of more than 100 frames per second is possible, it can be effectively applied to an actual production line, thereby improving productivity, and applying it online in real time to determine welding defects in real time to determine defective products. There is an advantage of being able to find and perform reinforcement welding for the defect immediately.

Although the above-described embodiment has been described for a preferred embodiment of the present invention, the present invention is not limited thereto, and it is specified that the present invention can be changed and implemented in various forms without departing from the technical spirit of the present invention.

100: inspection device 110: housing
111: display unit 120: laser vision sensor
130: control module 131: standard data storage unit
132: profile storage unit 133: dimension calculation unit
134: Defect determination unit 135: Orthogonal projection calculation unit
140: charging module

Claims (7)

housing;
A laser vision sensor installed in the housing and including a laser light source for scanning two or more laser beams on a welding surface of a workpiece, and an image camera for obtaining a profile of a weld bead by detecting the laser light scanned on the welding surface; And
A standard data storage unit storing standard welding condition information for welding process, joint shape, wire feeder speed, welding current, welding voltage, and welding speed, and standard dimension information of the welding unit; A profile storage unit for receiving the image of the welding bead obtained from the image camera of the laser vision sensor unit, processing the image, and converting the image into a digital profile and storing it; A dimension calculation unit that calculates a cross-sectional dimension of a weld bead of a profile stored in the profile storage unit; And a control module comprising; a defect determination unit configured to determine whether or not the welding bead is defective by comparing the welding condition information and standard dimension information of the data storage unit with the cross-sectional dimension information calculated by the dimension calculation unit, and
The dimension factor calculated by the dimension calculation unit is,
_{The distance L 1} between the left bead point and the right bead point of the weld bead;
_{A distance L 2} between the L ₁ and the vertices of the semicircular weld bead;
_{A distance L 3} between the bead point on the left side of the weld bead and the straight line of the lower base material;
The area A of the weld bead on the L _{1;
An angle θ 1} between a straight line of the lower base material and a straight line of a weld bead 2 mm away from the straight line of the lower base material;
Portable type welding quality inspection apparatus further comprising an angle θ ₂ ; between the straight line of the lower base material and the L _1.
The method according to claim 1,
It characterized in that it further comprises a display unit that is provided on one side of the housing and outputs together with the angle length, penetration, and tensile strength values of the weld bead calculated by the dimension calculating unit, and the determination result determined by the failure determination unit. Portable type welding quality inspection device.
The method according to claim 1,
Portable welding quality inspection device, characterized in that it further comprises a charging module provided inside the housing to supply power to the inspection device.
The method according to claim 1,
The control module further comprises an orthogonal projection calculating unit that calculates a slope from two or more profiles obtained by two or more laser light sources, and calculates an orthogonal projection, which is a vertical section of the bead from the slope value. Inspection device.
delete A welding quality inspection method using the portable welding quality inspection device according to claim 1,
The welding quality inspection method includes: receiving an image from the laser vision sensor, grabbing, filtering, thresholding, and thinning the welding bead by a profile storage unit of the control module. And performing image processing consisting of profiling.
The method of claim 6,
And calculating range data after the profiling step.

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