MXPA97004633A - Optical inspection device for direct inspection of solded or soldier joints - Google Patents

Abstract

The invention relates to a test apparatus for the direct evaluation of parts (1, 2) connected to each other by means of welded or soldered pieces (3). By means of a guiding unit (4 to 7) the parts (1,2) connected to each other is maintained at a constant distance from a sensor unit (8a, 8b) placed on at least one of the sides, but preferably in both sides of the parts (1, 2). The sensor units (8a, 8b) are part of a test apparatus that also includes an evaluation unit. At least one sensor unit (8a) includes a joint search unit (11), a two-dimensional sensor (12) and a fault detection unit (13), and, as a rule, a three-dimensional sensor of the joint profile ( 14). The two-dimensional joint sensor, the fault detection unit (13) and the three-dimensional sensor of the joint profile are placed in the center of the joint (3), depending on their position as determined by the joint search unit ( eleven). If the two-dimensional sensor (12) detects a fault by means of the evaluation unit, a fault detection unit is activated, which analyzes the location of the fault by means of the photo-section procedure. The three-dimensional sensor of the profile of the joint also works by means of the photo-section procedure, in combination with the triangulation of the light beam. The measurement results can be used for statistical process control (SPC) and / or to control the welding and soldering process, as well as the production facility.

Description

OPTICAL INSPECTION DEVICE FOR DIRECT INSPECTION OF WELDED OR WELDED JOINTS In order to maximize its weight and strength, the size of the structural elements is determined according to the local load. Especially in the automotive industry there has been a transition to individually determining the dimensions of the structural elements that have a different thickness, for example, determining the areas susceptible to collapse with a dimension that is thinner than the compartment for the passengers. To satisfy these demands, structural elements are used, consisting of parts with different dimensions that are connected to one another by means of a joint, more specifically, a welded piece. The quality of the welded piece is a decisive factor so that these structural elements can perform their function during the operation.

The normal method to verify a welded piece is by means of an optical inspection carried out by a specialized operator.

It is clear that this method can not ensure an objective inspection using identical criteria. The optical detection of a fault by an operator is absolutely impossible when a structural element passes through a test station at the normal process speed of, for example, 12m / min. Moreover, it is often difficult to distinguish by visual inspection a real flaw from an apparent one.

This may also be due to the different reflection properties of the surfaces of the structural elements, which may or may not have metallic coating. The dirt on the surface and color of the annealed steel in the area of the weldment makes it difficult to distinguish between real and merely apparent faults.

In a process just released for the measurement of seals in the course of a system is monitored joints (DE 43 12 241 Al), the surface of a piece is illuminated in the area of the board and is recorded by means of a area image recorder to make an evaluation of the image by shade of gray. The board is also examined intermittently by means of the photo-section procedure. The evaluation of the image by tonality of the gray is carried out by means of the photo-section procedure between the projection phases. The purpose of this procedure is to locate the position of the welded piece on the surface, and not evaluate its quality.

One of the purposes of the invention is to provide a test apparatus for welded parts or welded joints of parts connected to each other, which identifies and analyzes failures even at high rates of productivity.

This problem is solved by a test apparatus that has the following characteristics: a) The parts connected to one another are kept some distance from a sensor unit by means of a guide unit. b) The information related to the position of the joint is provided by a joint search unit having an optical sensor in whose measuring field is the joint, and an evaluation unit connected to the sensor. c) Depending on the information related to the position of the joint, a two-dimensional optical sensor whose measuring field is adapted to the width of the joint is placed in position by means of an adjustment element, in such a way that the center of the joint and the center of the measuring field coincide exactly, and d) Depending on the two-dimensional faults detected by the two-dimensional sensor, a fault detection unit is activated and analyzes the location of the fault.

The test apparatus according to the invention gathers the elements that are decisive for the geometric and qualitative evaluation of the joint in an optimum measuring position, so that the faults in the surface and the width of the joint can be satisfactorily identified even with high production rates. The results of the analysis can be displayed and recorded, for example, in the form of a report of the article under test, or used to control the welding process or solder welding. In particular, the known process of photo-section has become the process established to analyze the location of the faults (Germán Journal: "Kontrolle", September 1991, pages 5 to 14). However, if the only objective is to determine the area in which the detected fault extends, it would be sufficient not to study the point by means of the photo-section procedure, but to make the joint be recognized by an appropriate sensor by means of the use of adequate additional lighting.

Because the quality of the joint also depends, for example, on whether it has decreased or is too high, according to a feature of the invention the geometry of the joint is determined by means of a three-dimensional sensor of the joint profile that works with the photo-section procedure and is based on the triangulation principle of the light beam.

To obtain the optimum position and perform an accurate optical determination of the joint, according to a first feature of the invention and depending on the information related to the position of the joint provided by the joint search unit with the optical sensor and the unit When the evaluation element is connected, the adjustment element places the three-dimensional optical sensor of the joint profile so that the center of the joint and the center of the measuring field coincide exactly.

Preferably, a three-dimensional optical sensor of the joint profile is placed in each of the lateral parts connected to each other.

For the precise optical determination of the width of the joint, a distinction must be made between the joint, the smoke deposit and the colors of the annealed steel of the metal surfaces. According to a feature of the invention, structured area lighting is used to illuminate the joint, especially using infrared light, to eliminate these interferences.

For the optical examination of a welded piece or welded joints, as a rule, it is not enough to examine the joint only from one side of the parts connected to each other. Likewise, according to another feature of the invention, a two-dimensional optical sensor and a fault detection unit are provided on each of the two sides of the parts connected to one another.

The invention will now be explained in greater detail, with reference to an embodiment thereof which is illustrated in the drawings, in which it is shown: Fig. 1 a test apparatus without evaluation unit for a welded part, seen in the direction in which the joint runs, Fig. 2 the test apparatus shown in Fig. 1, shown schematically without the evaluation and guidance units, and viewed transversely to the direction in which the joint runs.

Fig.3 a diagram that illustrates the measurement principle of the beam triangulation.

Fig. 4 a schematic presentation of the photo-section procedure used in conjunction with the light beam triangulation.

Fig. 5a an image of a welded piece, provided by a two-dimensional sensor, and Fig. 5b the image of the location of a fault, which provides and analyzes a fault detection unit.

Referring to the Fiy. 1, between the ldillo and 4,!?, G, 7 of a guide unit is placed a structural element that includes two sheets of metal 1, 2 with different thickness, connected to each other by means of a welded piece 3. Therefore, the structural element 1, 2 can be moved in the direction of the welded part 3. Positioned in rigid spatial relationship to the rollers 4 to 7 is a test apparatus including an upper sensing unit 8a and a sensor unit lower 8b. The welded part 3 and the adjacent areas are illuminated by means of structured illumination of area 9a, 9b, specifically using infrared light. The angle of incidence, the wavelength and similar issues of the illumination 9a, 9b are selected in such a way that the interferences such as dirt, reflections and the like are materially suppressed to the maximum to take the image.

As shown in Fig. 2, the upper test apparatus has a number of units 11, 12, 13, 14 arranged one after the other in the direction in which the welded piece 3 runs. The welded piece 3 is first scanned by means of a joint search unit 11 having an optical sensor lia. Due to the position of the welded piece 3 it can also be located with a lateral displacement in relation to the center shown in Fig. 1, the joint search unit 11, with its sensor lia, must cover the entire range of possible positions of the joint 3. Next a connected evaluation unit (not shown) analyzes the place where the joint 3 is located. The evaluation unit issues an adjustment signal to an adjustment element 15. According to the adjustment signal, the adjustment element 15 adjusts the sensor unit 8a-8b transversely to the direction in which the welded part 3 runs, so that the two-dimensional optical sensor 12a may follow in series the sensors 13a, 14a of the following units 13, 14 arranged centrally in relation to the welded part 3. Then the two-dimensional sensor 12a provides an image, as shown in Fig. 5a. The evaluation unit of the two-dimensional sensor 12a analyzes the images in search of actual or apparent faults, and also to determine the width of the joint. However, this information related to faults does not allow to distinguish between real and apparent faults.

In order to distinguish between apparent and real faults, the two-dimensional sensor 12 is connected to a fault detection unit 13. The fault detection unit 13 operates by means of the photo-section procedure and for this purpose has a sensor optical 13a, specifically a CCD matrix camera, a light beam projector 13b and an evaluation unit (not shown). Fig. 5b shows the image taken by the optical sensor 13a.

Therefore, using the sensor unit 8a described above in this document, it is possible to determine the joint width and the actual faults. Because in many cases this information is insufficient to be able to evaluate the quality of a welded part, the fault detection unit 13 is connected to the above-mentioned three-dimensional sensor of the profile of the joint 14 with a laser diode 14a. and a camera with CCD matrix 14b. The three-dimensional sensor of the profile of the joint 14a works by means of the photo-section procedure together with light beam triangulation. In Figs. 3 and 4 the principle of operation is illustrated.

Since the optical evaluation of the quality of a welded part 3 from only one of the sides is not adequate, both sides of the welded part 3 are tested in the embodiment of the invention. However, for this purpose, not all units described for one side should be considered. It is sufficient to have an additional two-dimensional sensor, an additional fault detection unit, and a three-dimensional sensor of the additional welding profile, since the information of the joint search unit can be used to adjust the sensor units on both sides .

The special advantages of the test apparatus according to the invention is that it allows to determine, in a non-destructive manner and directly, the quality of a welded part or of a soldered joint, in terms of joint faults, joint width and profile of the joint. board. The results obtained can be registered and / or used to control the welding process or tin welding, in addition to the production facility. The invention can be used for different types of welded pieces and / or welded joints in different metallic materials with and without metal coatings, including combined constructions and for welded pieces and welded joints produced by means of different processes. It can be used for both fixed and mobile structural components. The test apparatus according to the invention can be used with greater advantage in conjunction with a welding or soldering unit. If the sensor unit is coupled to the process head, the unit is automatically guided together with the welded part. In this case it will only be necessary to determine the precise position of the joint, by means of the joint search unit, to adjust the actual sensor unit.

Claims (6)

1. An optical inspection device for the direct inspection of welded or tin-welded joints, especially metal sheets, connected to each other, with the following characteristics: a) The parts (1, 2) connected to each other are kept at a certain distance from a sensor unit (8a, 8b) by means of a guide unit (4, 5, 6, 7). b) The information related to the position of the joint (3) is provided by a joint search unit (11) having an optical sensor in whose field of measurement the seal (3) resides, and an evaluation unit connected to the sensor (lia) c) Depending on the information related to the position of the joint (3), a two-dimensional optical sensor (12) whose measuring field is adapted to the width of the joint (3) is placed in position by means of an adjustment element (15), in such a way that the center of the joint and the center of the measuring field coincide exactly, and d) depending on the bidirectional faults detected by the two-dimensional sensor (12), a fault detection unit (13) is activated and it analyzes the location of the fault.

2. A test apparatus according to claim 1, characterized in that depending on the information related to the position of the seals (3) provided by the joint search unit (11) with the * optical sensor (lia) and the unit connected evaluation, the adjustment element places a three-dimensional optical sensor of the profile of the gasket (14) -so that the center of the gasket and the center of the measuring field coincide exactly.

3. A test apparatus according to claim 1, characterized in that the three-dimensional optical sensor of the profile of the seal (14) operates by means of the photo-section procedure together with a triangulation of the light beam.

4. A test apparatus according to claim 1 or 2, characterized in that a structured area illumination (9a, 9b) is used to illuminate the joint (3).

5. A test apparatus according to claim 1, characterized in that it has a two-dimensional optical sensor (12) and a fault detection unit (13) on each of the two sides of the parts (1,2) connected to each other

6. A test apparatus according to claim 2, characterized in that it has arranged a three-dimensional optical sensor of the profile of the gasket (14) on each of the sides of the parts (1,2) connected to each other. Word in Fig. 2: Stromversorgung = electric power supply.