Method and device for non-destructive testing of weld seams

Abstract

A method for detecting the integrity of a joint (12; 106; 130; 140; 150; 160; 170) of a multi-part workpiece (100), comprising: acquiring a first image of the workpiece (100); subjecting the workpiece (100) to a load; acquiring a load image of the workpiece (100); comparing the first image of the workpiece (100) with the load image of the workpiece (100) to generate a shear image; and comparing the shear image with a reference image to detect the joint (12; 106; 130; 140; 150; 160; 170) of the multi-part workpiece (100), wherein comparing the shear image with the reference image comprises measuring an area of ​​the joint (12; 106; 130; 140; 150; 160; 170).

Description

TECHNICAL AREA

[0001] This disclosure concerns the non-destructive testing of a weld fusion. BACKGROUND

[0002] The information in this section provides only background information regarding the present disclosure and cannot establish the state of the art.

[0003] Joining is a process for joining two materials to form a single, cohesive material within a workpiece. The joining process can include gluing, welding, and crimping. The two materials can be the same material, i.e., metals or plastics combined, or different materials, i.e., a combination of different metals or a combination of metals and plastics. In the case of welding, the two materials typically have a similar chemical composition, e.g., each consisting of ferrous or non-ferrous metals, or they can have different chemical compositions, e.g., by combining ferrous and non-ferrous materials.Welding processes can include many forms including arc welding, oxygen-fueled flame welding, resistance welding, electroslag welding, laser welding, ultrasonic welding and electron beam welding.

[0004] Welding can be localized or extend over the length of the interaction with the workpiece. Examples of localized welding include spot welding and projection welding. Spot welding is typically a form of resistance welding in which two electrodes hold the workpiece together and current is passed through the electrodes to form a weld nugget. Projection welding uses raised sections on one or both of the materials being joined. Heat can be applied to these raised sections to create a weld nugget at the projections.

[0005] The welding process has many parameters that must be considered, including duration and the amount of energy used. Once these have been determined, the welding process can be repeated consistently. A change in either the duration or the amount of energy supplied can result in poor weld integrity or no weld integrity at all if an incomplete or no weld is formed in the workpiece. An incomplete, poorly intact, or no weld leads to inferior joint properties, such as strength and electrical conductivity, and can cause unexpected workpiece behavior. SUMMARY

[0006] A method for detecting the integrity of a joint of a multi-part workpiece comprises taking a first image of the workpiece, loading the workpiece, taking a loading image of the workpiece, and comparing the first image of the workpiece with the loading image of the workpiece to determine the integrity of the joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] One or more embodiments will now be described by way of example with reference to the accompanying drawings, in which:

[0008] Fig. 1 schematically illustrates an exemplary inter-cell connector with a plurality of welds for use in a battery in accordance with the disclosure;

[0009] Fig. 2 a schematic illustration of a shearography testing device in use on a workpiece in accordance with the present disclosure;

[0010] Fig. 3 a schematic illustration of an exemplary workpiece with a connected surface and a free surface with a representative shear diagram during a stress in accordance with the disclosure;

[0011] Fig. 4-1, Fig. 4-2 and Fig. 4-3 Schematic illustrations of shearography results during vibration testing of a workpiece with three good spot welds at different vibration frequencies, 4.5 kHz, 9.3 kHz and 11.5 kHz, in accordance with the present disclosure; and

[0012] Fig. 5-1, Fig. 5-2 and Fig. 5-3 Schematic illustrations of shearography results during vibration testing of a workpiece with a single good spot weld at different vibration frequencies, 5.0 kHz, 8.7 kHz and 11.9 kHz, in accordance with the present disclosure. DETAILED DESCRIPTION

[0013] Now, with reference to the drawings, which are shown only to illustrate certain exemplary embodiments and not to limit them, the following is illustrated Fig. 1. Schematic representation of an exemplary inter-cell connector 10 , which has a large number of connection points, i.e. spot welds 12 , includes, for use in a battery. The cell connector 10 includes a connector rail 14 , to produce a variety of plates 16 to connect them. The connector rail 14It has a generally U-shaped cross-section, which extends from a first end 18 to a distal second end 20 extends. The U-shaped cross-section includes a base. 22 and a first and a second fastening element 24 or 26 The second ending 20 includes a connecting flag 28 , to connect the battery to other batteries and devices as required for a specific application.

[0014] The first and second fastening element 24 , 26 are linked to a respective first and second set from a multitude of records 30 , 32 welded. The first and second sets are made from a variety of plates. 30 , 32 includes an inner plate 34 , a medium plate 36 and an outer plate 38 Since the first and second sets are made from a variety of records 30 ,32 are identical [engl. iares], only the first set from a multitude of plates is used. 30 described in detail. The inner plate 34 , the middle plate 36 and the outer plate 38 include a vertical section 40 , which is the vertical fastening element 24 Generally, the parts overlap to join them. In the exemplary embodiment, the connection is made by three spot welds. 12 reached, which is the first set from a multitude of records 30 on the connector rail 14 fix the inner plate 34 runs below the base 22 , is inwards towards the center of the base 22 It is stepped down and then runs in a generally vertical direction downwards from the base. 22 away from a lower edge 42 The middle plate 36 It generally runs vertically downwards to a lower edge. 44, which with the lower edge 42 in a row. The outer plate 38 is around the middle plate 36 symmetrically around the inner plate 34 opposite, i.e., the step goes outwards, from the center of the base 22 away, and has a lower edge 46 up, which with the lower edge 42 in a row. The inner plate 34 , the middle plate 36 and the outer plate 38 They can then be placed in an electrolyte container to initiate a chemical reaction that produces electrical energy. It will be evident that the first and second sets consist of a multitude of plates. 30 , 32a variety of grid plates, plant plates, flat plates, tubular plates or any other electrode capable of transferring electrical energy when placed in an electrolyte.

[0015] Each spot weld 12 the inner plate merges 34 , the middle plate 36 and the outer plate 38 with the connector rail 14 and allows an efficient current flow from each of the inner, middle and outer plates 34 , 36 , 38 to the connector rail 14 The connector rail 14 It transmits the current flow to the other batteries or devices connected to it. A defective spot weld. 12 , which does not perfectly integrate a single plate with the rest of the multitude of plates 30 , 32 and with the connector rail 14The weld melts, creating a suboptimal current flow and potentially preventing any current flow at all. The defective spot weld 12 This can prevent the battery from providing the expected amount of current and thus prevent the proper operation of a powered device. The defective spot weld 12 can be detected using shearing.

[0016] Fig. Figure 2 is a schematic illustration of a shearography testing apparatus. 50 for use on a workpiece 100 e.g. the inter-cell connector 10 The shearography testing apparatus 50 includes a laser 52 , a wedge 54 , a lens 56 and an image recording device 58 The laser 52 is a light-emitting device that can be precisely aimed at illuminating specific areas of a target or the entire target, e.g., the workpiece. 100, to shine on. The wedge 54 It is able to change the path of the light source by a predetermined amount. The lens 56 It receives diverging light emissions and focuses them at a predetermined distance to maintain a scaled image. The image acquisition device 58 A digital image capture sensor, such as a CCD sensor, as is generally known in the technical field, is capable of recording an image projected onto the sensor. The lens 56 is located between the workpiece 100 and the image recording device 58 at a predetermined distance to measure the light emissions in accordance with the shearography testing apparatus 50 to refocus. The wedge 54 is located between the workpiece 100 and the lens 56 and is over half of the lens 56positioned to effect a corresponding change in the light path for one half of the lens 56 to generate incoming light.

[0017] The workpiece 100 is within the shearography testing apparatus 50 arranged in a way that allows the laser 52 the workpiece 100 illuminates. The light from the laser 52 can be achieved by a beam splitter 60 through to the workpiece 100 be projected. The beam splitter 60 The light from the laser is distributed 52 over a larger area than the original light beam, as if through a first beam 62 or a second beam 64 It is shown that the explanation of the first ray 62 and the second ray 64 This only applies to simply defined reference points, and that the section between the first ray 62 and the second beam64 behaves similarly to the nearest reference beam.

[0018] The first ray 62 beams the first point 66 on the workpiece 100 on, which leads to a lens 56 in a first upper ray 68 and a second lower beam 70 is refracted. The second beam 64 shines the second point 72 on the workpiece 100 on, which leads to a lens 56 in a second upper beam 74 and a second lower beam 76 is broken. The first lower beam 70 and the second lower ray 76 enter the lens 56 one and are at a first projected point 86 and a second projected point 88 on the image recording device 58 projected.

[0019] The first upper ray 68 and the second upper ray 74will be placed on the wedge 54 projected. The wedge 54 breaks up the main part of the first upper ray 68 and the second upper ray 74 and thereby creates a shift of a predetermined amount. The portion of the light that is not shifted is focused by a first focal beam. 80 and a second beam 82 A first image is shown to the image capture device. 58 presented as by the first projected point 86 and the second projected point 88 shown, which represents the surface of the workpiece 100 between the first point 66 and the second 72 represents the first upper ray. 68 and the second upper ray 74 show a focal point along the line 84 at the same distance between the lens 56 and the image recording device 58 like the first beam of light80 and the second focal beam 82 The image capture device 58 A second image is presented, as if by a shifted first projection point. 90 and a shifted second projection point 92 displayed, the latter being the position of the first projected point. 86 corresponds.

[0020] The resulting first and second images represent a superimposed first image on the image acquisition device. 58 ready, which is recorded. The workpiece 100 is subjected to a stress, e.g. changes in strain, temperature, vacuum or vibration, and subsequently the image acquisition device 58 A superimposed stress image is recorded. The first image and the stress image are compared, i.e., added or subtracted, to identify shear lines and impurities in the workpiece. 100to determine and generate a shear pattern. The shear pattern can be compared with a reference image, which shows an expected resulting image. The comparison can be done either manually or automatically. It is obvious that if the workpiece 100 is subjected to vibration stress, the images at the extremes of the excitation of the workpiece 100 , i.e., at a position closest to and furthest away from the image capture device 58 , can be recorded.

[0021] Fig. Figure 3 is a schematic illustration of an exemplary workpiece. 100 with a connected surface such as a weld, a free surface, a surface without any connection, with a representative shear diagram under stress. The workpiece 100 includes an upper element 102 and an adjacent lower element 104, which is a single common connected surface, i.e., a spot weld 106 exhibit. The load is distributed evenly across the workpiece. 100 along the upper and lower elements 102 , 104 in one direction from the spot weld 106 , in the direction indicated by arrows 108 The spot weld is shown. 106 maintains the relationship between the upper and lower elements 102 , 104 upright, whereas deflection increases as the distance from the spot weld increases, as indicated by the dashed lines. The strain diagram 110 shows an area without stretching 112 which of the size of the spot weld 106 This corresponds to a relatively strong stretch. 114 adjacent to the spot weld 106 present, which decreases when the distance from the spot weld is increased. 106 increases.

[0022] It can cause vibration stress. 116 applied to the workpiece. The vibration stress 116 It can be applied randomly or controlled to a specific frequency or range of frequencies. The vibration stress 116 This leads to a similar event as described above regarding the load. That is, if the workpiece 100 The point at which the workpiece is stimulated retains its position. 100 joined, i.e. spot-welded 106 is the relationship between the upper and lower elements 102 , 104 The deflection of the upper and lower elements 102 , 104 The strain increases as the distance from the spot weld increases, as indicated by the dashed lines. The strain diagram 110 remains the same, i.e., the area without stretching. 112 corresponds to the size of the spot weld 106, and a relatively strong stretch 114 adjacent to the spot weld 106 decreases when the distance from the spot weld 106 increases. This relationship applies to a single spot weld. 106 or a series of spot welds. The frequency of the vibration stress 116 It can be modified in this way to match the spacing of the spot welds in order to provide easily distinguishable shearography results. It will be evident that the vibration stress 116 at the natural frequency of the workpiece 100 or may lie on one or more parts that form the workpiece.

[0023] Shearography is capable of measuring the stretching 114 adjacent to the spot welds 106 to detect by identifying a node at the location of the spot weld 106 produced, i.e., the spot welds 106will show a consistently shaded image during the shearography image comparison. Where the spot weld is located 106 If the weld exhibits poor or no weld integrity, the shearography image will show partial deflection by means of a shaded change through the section of the spot weld that exhibits poor or no weld integrity.

[0024] The Fig. 4-1, Fig. 4-2 and Fig. Figures 4-3 are schematic illustrations of shearography during vibration stress on a workpiece with three good spot welds at different vibration frequencies, 4.5 kHz, 9.3 kHz and 11.5 kHz. Fig. 4-1 represents the workpiece excited to a vibration frequency of 4.5 kHz. 100 and represents three nodes 130 , a left node 131 , a middle node 133 and a right-hand node135 This shows which three spot welds are indicated. The nodes 130 well-formed spot welds indicate, i.e., the respective nodes 130 They correspond to the overall shape of the spot weld. A double image of the left, middle, and right nodes. 131 , 133 , 135 Shear lines appear as a consequence of the shearography images being taken at the extremes of the vibration cycle; that is, the point furthest from the camera and the point closest to the image-taking device are superimposed, as described above. Shear lines appear at a frequency of 4.5 kHz. 132 which revolve around the combination of the three nodes 130 wrap around. The shear lines 132 generally begin below the middle and left nodes 133 or 131 at the edge of the workpiece and run upwards to the corresponding node 130to the left and to the right. The shear lines 132 run around the left node 131 around and above it. The shear lines 132 They continue by extending to the right node with a general upward trend. Further shear lines begin at the top of the middle and right nodes and follow the same general pattern.

[0025] Fig. 4-2 represents the workpiece excited to a vibration frequency of 9.3 kHz. 100 and represents three nodes 140 , a left node 141 , a middle node 143 and a right-hand node 145 which show three spot welds. Each of the nodes 130 shows well-formed spot welds. The double image of the nodes 140This occurs because the shearography images were recorded at the extremes of the vibration cycle, as explained above. Due to the higher frequency relative to Fig. 4-1 the lower shear lines occur 142 along the underside of each of the nodes 140 in a generally semi-elliptical pattern with a closed end in a row with the respective node 140 and an open end extending towards the end of the workpiece. Since each of the left node 141 , the middle node 143 and the right node 145 associated lower shear lines 142 exhibits, the lower shear lines help 142 to determine if the spot weld is well-formed. The upper shear lines 144 begin above each of the nodes 140 , run upwards and turn to the right in a generally horizontal direction.

[0026] Fig. 4-3 represents the workpiece excited to a vibration frequency of 11.5 kHz. 100 and represents three nodes 150 , a left node 151 , a middle node 153 and a right-hand node 155 which show three spot welds. Each of the nodes 150 shows three well-formed spot welds. The double image of the nodes 150 This results in the shearography images being recorded at the extremes of the vibration cycle, as explained above. Due to the higher frequency relative to the Fig. 4-1 and Fig. 4-2 the lower shear lines behave 152 along the underside of the nodes 150 different. The lower shear lines 152 exhibit three groupings, each with a generally semi-elliptical pattern with a closed end towards the node 150there, but only the left set of lower shear lines 152 remains directly below the left node 151 The middle set of lower shear lines 152 is from the middle node 153 shifted and generally under a left side of the middle node 153 aligned. The right set of lower shear lines 152 is below the right node point 155 formed, but continues under a right section of the middle node 153 The upper shear lines 154 are generally above each of the nodes 150 centered and run upwards, then turn right in a generally horizontal direction.

[0027] The Fig. 5-1, Fig. 5-2 and Fig. Figures 5-3 are schematic illustrations of shearography during vibration stress on a workpiece with a single good weld at different vibration frequencies, 5.0 kHz, 8.7 kHz and 11.9 kHz. Fig. 5-1 represents the workpiece excited to a vibration frequency of 5.0 kHz. 100 and shows a single node 160 on, which has a well-formed spot weld and a left and a middle recess 162 , 164 It indicates areas where spot weld formation has failed. A double image of the node. 160 and the left and middle depressions 162 , 164 As a consequence, the extremes of the shearography images of the vibration cycle were recorded; that is, the point furthest from the camera and the point closest to the camera lie on top of each other. The shear lines 166 surround the right node 160due to the stability of the spot weld. Both the left and the middle recess 162 , 164 include a series of shear lines 166 , which are through the left and middle depressions 162 , 164 run through it. The one through the left and the middle depression 162 , 164 shear lines running through 166 show a failed spot weld in each of the left and middle indentations. 162 , 164 to.

[0028] Fig. 5-2 represents the workpiece excited to a vibration frequency of 8.7 kHz. 100 and shows a single node 170 and a left and a middle depression 172 , 174 Each image is attached to surfaces where the formation of spot welds has failed. A double image of the node. 170 and the left and middle depressions 172 , 174This occurs because the shearography images were taken at the extremes of the vibration cycle, as explained above. The left and middle depressions 172 , 174 These lines indicate the location of a failed spot weld. 176 surround the right node 170 due to the stability of the spot weld. The shear image of the junction. 170 is smaller than the corresponding indentation, indicating a spot weld that is smaller than expected and poor weld integrity. Both the left and middle indentations 172 , 174 include a series of shear lines 176 , which are through the left and middle depressions 172 , 174 run through and represent failed spot welds at the left and middle depression points.

[0029] Fig.5-3 represents the workpiece excited to a vibration frequency of 11.9 kHz. 100 and shows a single node 180 and a left and a middle depression 187 , 184 Each image is attached to surfaces where the formation of spot welds has failed. A double image of the node. 180 and the left and middle depressions 182 , 184 This occurs because the shear images were recorded at the extremes of the vibration cycle, as explained above. The shear lines 186 surround the right node 180 due to the stability of the spot weld. The right node 180 It has approximately the same shape as the corresponding indentation, indicating a well-formed spot weld. Both the left and the middle indentation 182 , 184 exhibit a number of shear lines 186up, through the left and the middle depression 182 , 184 running through, indicating failed spot welds at each of the left and middle indentation points.

[0030] The above description provides information that can be used to assemble a non-destructive joint detection system when the workpiece is loaded and when images of loaded and unloaded joints, as well as images of loads during excitation extremes, are acquired. One example might be to provide a single frequency that is predicted to produce shear lines for shearographic imaging through unconnected parts to detect a sound joint. Another example might be to tune the vibration frequency to the natural frequency of the connected or unconnected workpiece for shearographic imaging to detect a sound joint. Yet another example might be to provide a range of frequencies for shearographic imaging to detect a sound joint.Another example involves taking an image without a load and then subjecting the workpiece to a stress test. In each case, a series of reference tables or charts can be used to determine acceptable spot weld integrity through inspection, whether performed manually or automatically. Furthermore, an area calculation can be used to determine whether an appropriate degree of joining has occurred at each joint point on a workpiece.

[0031] The disclosure has described certain preferred embodiments and variations thereof. After reading and understanding the description, someone may think of further variations and modifications. Therefore, the disclosure should not be limited to the specific embodiment(s) considered the best way to implement the disclosure, but rather should encompass all embodiments that fall within the scope of protection of the accompanying claims.

Claims

[1] Method for detecting the integrity of a joint of a multi-part workpiece, comprising: a first image of the workpiece is taken; the workpiece is subjected to stress; A stress image of the workpiece is recorded; and The first image of the workpiece is compared with the load image of the workpiece to determine the integrity of the connection point. [2] Method according to claim 1, wherein loading the workpiece comprises exerting a tensile force on the workpiece. [3] Method according to claim 1, wherein comparing the image of the workpiece with the load image of the workpiece to determine the integrity of the joint comprises calculating the area of ​​the joint. [4] Method according to claim 1, wherein the workpiece comprises a multi-part battery connector. [5] Method according to claim 1, wherein the connection point comprises a weld. [6] Method for detecting the joint of a multi-part workpiece, comprising: a first image of the workpiece is taken; the workpiece is set into vibration; A stress image of the workpiece is recorded; and The first image is compared with the stress image to create a shear image. [7] Method according to claim 6, wherein the vibration setting of the workpiece comprises setting the workpiece into vibration at a series of frequencies. [8] Method according to claim 6, wherein the vibration setting of the workpiece comprises setting the workpiece into vibration at a series of predetermined frequencies. [9] Method according to claim 6, further comprising comparing the shear pattern with a reference image to detect the joint of the multi-part workpiece. [10] Method according to claim 9, wherein comparing the shear pattern with the reference image comprises calculating an area of ​​the joint. [11] Method according to claim 6, wherein the connection point comprises an adhesive.

Images