METHOD FOR DIMENSIONAL MEASUREMENT OF A METAL PLATE

Abstract

The present invention relates to the field of quality control in the metallurgical industry, and more specifically to a method for the dimensional measurement of a metal plate. The invention relates to a method for the dimensional measurement of a metal plate comprising the following steps: placing the metal plate in an area called the "acquisition zone" defined by the range of a set of scanners; placing localization elements in the acquisition zone; simultaneously acquiring a laser point cloud on all faces of the metal plate using the set of scanners; generating a measurement report by acquiring and processing the point cloud data via metrology software using the following process: i) acquiring point clouds using each scanner in the set of scanners;ii) exporting the point clouds acquired by each scanner to a computer interface and registering the point clouds via the computer interface to obtain a global point cloud; iii) importing the global point cloud into the metrology software; iv) determining at least one plate dimension by processing the global point cloud via the metrology software and obtaining a measurement report; optionally, comparing this measurement report with a standard measurement report presenting at least one target plate dimension. The present invention is useful, for example, for quickly and efficiently determining the dimensions of a metal plate, for example, an aluminum plate, whether or not it contains deformations.

Description

Title of the invention: METHOD FOR DIMENSIONAL MEASUREMENT OF A METAL PLATE Technical field of the invention

[0001] The present invention relates to the field of quality control in the metallurgical industry, and more specifically to a method of dimensional measurement of a metal plate.

[0002] The present invention is useful, for example, for quickly and efficiently determining the dimensions of a metal plate, for example an aluminum plate including or not deformations. Previous art

[0003] Dimensional measurement is a systematic step in the production of metal plates. This makes it possible, in particular, to identify plates with dimensions outside of tolerances or specifications, i.e., plates that will have excessive scalping and will therefore be too short or too thin for the desired applications.

[0004] Dimensional measurement is generally the technique used to dimension metal plates. Manual control is carried out by an operator using a tape measure, a ruler, a square, and / or any other measuring device of this type. However, this technique is the source of numerous difficulties, the three main ones being human error during measurement, the lack of reliability in measurement repeatability, the measurement time, and the time required to analyze the collected measurements.

[0005] In order to avoid such pitfalls, several solutions have been developed in the prior art.

[0006] It was considered to use a profilometer, an instrument used to measure the relief of a surface, particularly for the purpose of evaluating its roughness or micro-geometry. This device uses LIDAR (laser imaging detection and ranging) laser remote sensing, a remote measurement technique based on analyzing the properties of a light beam reflected back to its emitter. Unfortunately, this does not allow for reliably obtaining all the dimensions of a plate. Indeed, implementing a dimensional measurement technique for a metal plate using a profilometer involves moving the plate or the profilometer itself to obtain all the plate profiles. However, such movement generates vibrations and / or oscillations that lead to measurement errors.

[0007] Another approach considered involves the use of structured light devices. These devices comprise a projector that projects a light pattern onto an object, and a camera that records any deformations of the projected light pattern. The data collected, particularly the distances between the different points of the pattern, are then analyzed to generate a 3D model. Unfortunately, this is not suitable for the metallurgy sector because this technology cannot measure large objects, such as metal plates. Furthermore, this technology is sensitive to variations in light, which can negatively affect the quality and reliability of the measurements.

[0008] Thus, to date, no dimensional measurement method for a metal plate that is satisfactory in terms of reliability or repeatability has been proposed. There is therefore a real need to find a fast, and consequently economically advantageous, and accurate method that does not present the drawbacks of the prior art. Description of the invention

[0009] The present invention is specifically designed to meet these needs and resolve the problems and drawbacks of the prior art by providing a method for the dimensional measurement of a metal plate. The method of the invention advantageously eliminates data entry errors by an operator, ensures repeatability of the measurements performed, and improves the speed of dimensional measurement while automatically archiving the collected information. Furthermore, the method according to the invention effectively detects all metal plates that do not meet precise specifications, i.e., metal plates that do not have the expected dimensions. Since the method according to the invention is easy to implement and quick, it is also very economically advantageous.

[0010] A first object of the present invention is a method for dimensional measurement of a metal plate comprising the following steps: - placement of the metal plate in an area called the "acquisition zone" defined by the range of a set of scanners; - implementation of a localization element in the acquisition area; - creation of a simultaneous laser point cloud on all faces of the metal plate using the set of scanners; - generation of a measurement report by acquiring and processing point cloud data via metrology software using the following process: i) acquisition of point clouds using each scanner in the set of scanners; ii) export of the point clouds acquired by each scanner to a computer interface and registration of the point clouds via the computer interface to obtain a global point cloud; iii) importing the global point cloud into the metrology software; iv) determining at least one plate dimension by processing the global point cloud via the metrology software and obtaining a measurement report; - possibly, comparison of this measurement report with a standard measurement report presenting at least one target plate dimension.

[0011] By "metal plate" is meant a plate comprising a metal or an alloy, that is to say a mixture of metals. For example, the plate may comprise at least one metal selected from cast iron, iron, steel, copper, nickel, aluminum, lead, zinc, tin, tungsten, molybdenum, tantalum, magnesium, cobalt, bismuth, cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium, germanium, vanadium, gallium, hafnium, indium, niobium, rhenium, thallium, preferably at least aluminum, and even more preferably the plate may be an aluminum plate.

[0012] Advantageously, the metal plate can have a length ranging from 1,500 to 10,000 mm, preferably from 2,000 to 9,500 mm and even more preferably from 2,200 to 9,200 mm.

[0013] Advantageously, the metal plate can have a width ranging from 900 to 3,000 mm, preferably from 900 to 2,750 mm and even more preferably from 950 mm to 2,500 mm.

[0014] Advantageously, the metal plate can have a thickness ranging from 100 to 800 mm, preferably from 200 to 700 mm and even more preferably from 370 to 630 mm.

[0015] The term "scanner" refers to a device capable of analyzing an object and / or its immediate surroundings to gather information on its shape and possibly its appearance. For example, a scanner may be chosen from a P30 reference scanner, marketed by LEICA Geosystems SAS, located in France; a P40 reference scanner, marketed by LEICA Geosystems SAS, located in France; a P50 reference scanner, marketed by LEICA Geosystems SAS (France); an RTC 360 scanner, marketed by LEICA Geosystems SAS (France); or any other 3D scanner known to those skilled in the art. Since the RTC 360 reference scanner is functional but may induce a loss of precision, the scanner may preferably be chosen from a P30, P40, or P50 reference scanner, or any other 3D scanner known to those skilled in the art.

[0016] By "acquisition zone" is meant an area in which the metal plate enters the range of the scanner assembly, that is to say an area for which The entire set of scanners can simultaneously detect the metal plate. The acquisition area can include a vertical axis and a horizontal axis.

[0017] By "localization element," we mean an element that allows the exact location of a point in a given space to be determined by precise 3D measurements. Thus, the localization element is a simple part, for example, spherical in shape, that allows the different points to be positioned relative to each other. These points, which form what is called a point cloud, can be transmitted to a scanner. This scanner can then measure the point density at 10m, generate a photo, in color or black and white, and / or size an acquisition window.

[0018] The localization element can be chosen from a sphere, a paper target, a checkerboard, a flat target, and a reference surface, preferably a sphere, and even more preferably a white sphere.

[0019] Advantageously, several localization elements can be placed in the acquisition zone. Preferably, the number of localization elements is between 4 and 6, and preferably the number of localization elements is 6.

[0020] Advantageously, if there are several localization elements, then the localization elements can be identical or different.

[0021] Advantageously, the localization element can be positioned arbitrarily within the acquisition area. Preferably, if the number of localization elements is from 4 to 6, then the localization elements can be positioned at different heights and with a circular distribution from the center of the acquisition area. Preferably, if the number of localization elements is from 4 to 6, then the localization elements can be positioned so that each scanner is able to detect at least 4 localization elements detected by another scanner.

[0022] By "measurement report" is meant a file or document comprising all or part of the measurements obtained by the method according to the invention.

[0023] The term “metrology software” means software that allows a user to create and / or execute a measurement routine. For example, the metrology software may be chosen from Spatial Analyzer (trademark), marketed by Hexagon metrology SAS, located in Saint Aubin, Polyworks (trademark), marketed by Polyworks Europa (France), and Metrolog X4 (trademark) marketed by Métrologie Group France.

[0024] By "computer interface," we mean a computer program enabling interaction between a computer system and its user, for example, between a scanner and its user. Advantageously, the computer interface allows the measurement parameters to be transmitted to the set of scanners, the measurements to be initiated, and the XYZ coordinates of the point clouds for each of the set to be retrieved. scanners, to calculate the registration parameters of the point clouds, to generate a global point cloud and to import said global point cloud into the metrology software.

[0025] By "point cloud acquisition" is meant the collection of information relating to each of the points constituting the cloud. The acquisition of a point can be carried out by a scanner covering at least one area of ​​a metal plate from a surface perspective. Thus, the scanner positions a point in space corresponding to a surface of the metal plate and defines this point relative to the other generated points.

[0026] By “registration”, we mean a process allowing the point clouds of the different scanners to be grouped together in order to form a single point cloud, called the global point cloud, which can then be analyzed.

[0027] By "export" we mean a process of transferring and / or saving data from the set of scanners to a computer interface.

[0028] By "point cloud", we mean a 3D digital representation of a metal plate which consists of several points placed in a coordinate system of x, y and z.

[0029] By "global point cloud" is meant a point cloud resulting from the grouping of at least two point clouds, acquired by at least two scanners, via the computer interface.

[0030] By "import" we mean a process of transferring and / or saving data from a computer interface to a software program.

[0031] By "dimension" is meant one or more of the measurements of the metal plate chosen from the length, the width, the thickness, the longitudinal deflections, the lateral deflections, the transverse deflections, the squareness.

[0032] By "longitudinal deflection" is meant a deflection of a face of the plate along a section in the plane perpendicular to the plane of placement of the plate and in the direction of the length of said plate.

[0033] By "lateral arrows" is meant an arrow from one face of the plate along a section in the plane parallel to the plane of placement of the plate and in the length direction of said plate.

[0034] By "transverse arrows", we mean an arrow from one face of the plate along a section in the plane perpendicular to the plane of installation of the plate and in the direction of the diagonal of said plate.

[0035] By “squaring”, we mean the verification of the perpendicularity of one of the angles between two faces of a metal plate.

[0036] Advantageously, in the method according to the present invention, the step of setting up the metal plate can be preceded by, or can include, a step of removing cutting chips.

[0037] The term "cutting chip" means a metallic splinter or fragment on one of the faces of a metal plate. The chip may originate from a cutting step that produced a metal plate of desired dimensions.

[0038] By "removal step" is meant a step of removing all or part of the cutting chips. Advantageously, the chip removal step can be implemented by an automatic blower system, i.e. a system equipped with a nozzle for expelling the cutting chips, or a simple blower used by an operator.

[0039] Advantageously, in the method according to the present invention, the step of placing the metal plate can be preceded by or can include a step of drying the plate.

[0040] By "drying stage" is meant the removal of all or part of the water contained on the surface of a metal plate.

[0041] Advantageously, the drying step can be implemented by an automatic blower system, i.e. a system equipped with nozzles, or a simple blow gun used by an operator.

[0042] Advantageously, the metal plate can be positioned on a support.

[0043] The term "support" means one or more objects that allow the metal plate to be raised above the ground, i.e., to be elevated above the ground. For example, the support may include mounting blocks, tripods, a metal structure, or the frame of an existing machine.

[0044] Advantageously, the set of scanners may include a scanner placed so as to overhang the metal plate, preferably scanners placed so as to overhang the metal plate.

[0045] Advantageously, the set of scanners may include at least two scanners, preferably at least four scanners.

[0046] Advantageously, the at least four scanners can be positioned to form a space surrounding the metal plate, preferably a rectangle in which the metal plate is located. Preferably, the at least four scanners can be positioned in a configuration comprising two scanners located at a height lower than the height of the metal plate and two scanners located at a height higher than the height of the metal plate.

[0047] The scanner(s) placed under the metal plate make it possible to measure the face of the metal plate oriented towards the ground, so as to measure the thickness of the metal plate when the latter has a twist or an irregularity.

[0048] Advantageously, the scanner assembly may further include at least one additional scanner placed below the metal plate, preferably two additional scanners. For example, the additional scanners may be independently placed at a height lower than the height of the metal plate or at a height higher than the height of the metal plate.

[0049] By "torsion" or "irregularity" is meant a deformation of the metal plate, resulting in the non-flatness of the plate.

[0050] Advantageously, the process of the invention may include the additional steps of - setting up a camera outside the acquisition area; - acquisition of at least one photograph of the metal plate using the camera; - integration of at least one photograph into the measurement report.

[0051] Advantageously, the step of placing the plate in the acquisition zone may include positioning the plate in the acquisition zone with or without an angle of inclination of the plate relative to the horizontal axis of the acquisition zone. For example, the angle of inclination may be greater than 0° and may be less than 180°, preferably less than 90°, preferably less than 45°, even more preferably less than 10°, and even more preferably less than 2.5°. This positioning aims to optimize the measurement uncertainty of the scanners by limiting the angle of incidence of the measurement and to optimize the acquisition time.

[0052] Advantageously, the analysis step can allow for the recording of one or more measurements of the metal plate chosen from among the length, width, thickness, longitudinal deflections, lateral deflections, transverse deflections, and squareness. Brief description of the figures

[0053] Fig. 1 schematically represents a metal plate (PM) on which is shown, for illustrative purposes, a measurement of length (LO), width (LA), thickness (EP), longitudinal deflection (FLO), lateral deflection (FLA), transverse deflection (FTR) and squareness (EQ).

[0054] Figure 2 schematically represents a top view of an acquisition area (ZA) delimited by four scanners (SC) comprising a metal plate (PM) in which the positioning of the plate in the acquisition zone includes an angle of inclination of the plate of 2.5° with respect to the horizontal axis (AH) of the acquisition zone.

[0055] Figure 3 schematically represents a profile view of a metal plate (PM) comprising a twist on two mounting studs (PP) for which two scanners (SC) are placed under said metal plate so that the measurements take into account said deformation.

[0056] Fig. 4 schematically represents a metal plate (PM) on which are shown, for illustrative purposes, different length measurements (LOI to LO5) for the same face of said metal plate. EXAMPLES

[0057] Other advantages, purposes and particular features of the present invention will become apparent from the following examples, presented for illustrative and non-limiting purposes, in the light of the accompanying figures.

[0058] Example 1: Example of dimensional measurement of a metal plate in an indoor environment

[0059] This example describes a dimensional measurement of a metal plate (MP) in an indoor environment, i.e., subjected to a light intensity of less than 1,000 lux. Indeed, the light intensity in this example is 513 lux.

[0060] The metal plate is made of aluminium (marketed by the company Aluminium Dunkerque, based in France).

[0061] An acquisition zone (AZ) is delimited by positioning four scanners (SC) so as to form a quadrilateral of 12915 mm x 6350 mm.

[0062] The scanners are P30 scanners (marketed by the company LEICA, LEICA Geosystems SAS domiciled in France.

[0063] The metal plate (PM) is positioned on two mounting blocks (PP) such that the center of the plate corresponds to the center of the two mounting blocks with a margin of error of plus or minus 20 mm. It should be noted that the margin of error has no real impact on the measurements as long as the metal plate remains within the measurement area. The two mounting blocks (PP) are positioned at the center of the acquisition area.

[0064] Six white spheres, reference number 109561, marketed by NESTLE, are placed in the acquisition zone to allow for the calibration of the scanners. The spheres are positioned in the acquisition zone so that each scanner can collect data relating to all six spheres.

[0065] An operator uses the computer interface to launch the measurements and obtain a point cloud simultaneously on all faces of the metal plate.

[0066] The computer interface exports the point clouds recorded by the scanners and registers them, so as to obtain a global point cloud including data on all faces of the metal plate.

[0067] Indeed, the scanners measure the plate and the spheres. The various coordinates created by the scanners are sent to the SCAN Press computer interface (marketed by SETIS Group, based in Grenoble, France) via a RJ45 cable. This computer interface allows the generation of different point clouds and their alignment using the received coordinates.

[0068] The data recalibrated from the computer interface and the global point cloud are sent to the Spatial Analyzer metrology software (marketed by the company Hexagon France located in Saint Priest): this is the global point cloud import step.

[0069] A measurement report is generated by the software. This report includes the length (LO), width (LA), thickness (EP), longitudinal deflections (FLO), lateral deflections (FLA), transverse deflections (FTR), and squareness (EQ) of the metal plate. These are the various measurements used to dimension the metal plate, as shown in [Fig. 1].

[0070] The length measurement is derived from the average of the length measurements at every point of the metal plate, as shown in [Fig.4]. The same applies to the other types of measurements.

[0071] Table 1: Measurement set of a metallic place in an indoor environment. [Tables 1] Measurements 1 2 3 4 5 Average Maximum Minimum Length (mm) 4997 4995 4994 4993 4991 4994 4997 4991 Width (mm) 1190 1188 1188 1188 1190 1188.3 1190.2 1185.6 Thickness (mm) 525 521 520 520 522 522.8 525.9 519.1 Longitudinal Deflection (mm) 3 6 4 4.3 6 3 Lateral Deflection (mm) 2 2 5 3 5 2 Transverse Deflection (mm) 3 3 3 3 3 Squareness (°) 89.73 90.29 89.95 90.02 89.50 80.29 89.73

[0072] A first repeatability test, called a "fixed repeatability test", was carried out for this example. For this, the same procedure was implemented more than 10 times without moving the metal plate.

[0073] A second repeatability test, called a "dynamic repeatability test", was carried out for this example. For this, the same procedure was implemented more than 10 times, moving the metal plate between each procedure.

[0074] Following the fixed and dynamic repeatability tests, the maximum difference observed between the different measurements is less than 2 mm. The acquisition area can therefore be adapted according to the needs (configuration of the environment dedicated to carrying out the measurements).

[0075] Example 2: Example of dimensional measurement of a metal plate in an outdoor environment

[0076] This example describes a dimensional measurement of a metal plate in an outdoor environment, i.e. subjected to a light intensity greater than 1,000 lux.

[0077] It should be noted that the metal plates in Examples 1 and 2 are both aluminum plates marketed by the company Aluminium Dunkerque. However, they differ in that they are not the same plate per se. Indeed, the dimensions of the metal plate used in Example 2 are different from those of the metal plate in Example 1 because each plate produced has slight variations.

[0078] Thus, the objective of example 2 is to demonstrate that the process of the invention works in an outdoor environment and not to obtain measurements demonstrating that the dimensions of the plate of example 2 are identical to those of example 1.

[0079] The same method as in Example 1 is implemented in the present example outside a building, in daylight, on a sunny day.

[0080] Table 2: Measurement assembly of a metallic place in an outdoor environment. [Tables 2] Measurements 1 2 3 4 5 Average Maximum Minimum Length (mm) 4025 4022 4021 4019 4017 4021 4025 4017 Width (mm) 1190 1188 1191 1190 1190 1189 1191 1188 Thickness (mm) 598 597 602 601 601 600 602 597 Longitudinal Deflection (mm) 4 8 6 6 8 6 Lateral Deflection (mm) 5 2 4 3.6 5 2 Transverse Deflection (mm) 7 6 6.5 7 6 Squareness (°) 90.02 90.07 89.71 89.66 89.87 90.07 89.66

[0081] The method of the invention implemented in Example 2 makes it possible to measure the dimensions of a metal plate without the light intensity affecting the measurement process. Thus, this highlights that the method according to the invention is not influenced by variations in light.

[0082] The method of the invention makes it possible to fully dimension a metal plate in a very short time, while eliminating human error by an operator. Furthermore, the method according to the invention is very economically advantageous.

Claims

Demands

1. A method for the dimensional measurement of a metal plate comprising the following steps: - placing the metal plate in an area called the "acquisition zone" defined by the range of a set of scanners; - placing a locating element in the acquisition zone; - simultaneously acquiring a laser point cloud on all faces of the metal plate using the set of scanners; - generating a measurement report by acquiring and processing the point cloud data via metrology software using the following process: i) acquiring point clouds using each scanner in the set of scanners; ii) exporting the point clouds acquired by each scanner to a computer interface and registering the point clouds via the computer interface to obtain a global point cloud; iii) importing the global point cloud into the metrology software;(iv) determination of at least one plate dimension by processing the global point cloud via metrology software and obtaining a measurement report; - possibly, comparison of this measurement report with a standard measurement report presenting at least one plate dimension.

2. Method according to claim 1, wherein the localization element is chosen from a sphere, a paper target, a checkerboard, a flat target and a reference surface.

3. A method according to claim 1 or 2, wherein the step of placing the metal plate is preceded by, or includes, a step of removing cutting chips

4. Method according to any one of claims 1 to 3, wherein the step of setting up the metal plate is preceded by or includes a step of drying the plate.

5. Method according to any one of claims 1 to 4, wherein the scanner assembly further comprises at least one additional scanner placed under the metal plate.

6. Method according to any one of claims 1 to 5, wherein the step of placing the plate in the acquisition zone includes positioning the plate in the acquisition zone with an angle of inclination of the plate relative to the horizontal axis of the acquisition zone greater than 0° and less than 180°.

7. A method according to any one of the preceding claims, wherein the step of determining at least one plate dimension allows one or more of the measurements of the metal plate to be taken, chosen from the length, width, thickness, longitudinal deflections, lateral deflections, transverse deflections, squareness.

8. Method according to any one of the preceding claims, wherein the metal plate has a length from 1,500 to 10,000 mm.

9. Method according to any one of the preceding claims, wherein the metal plate has a width ranging from 900 to 3000 mm.

10. Method according to any one of the preceding claims, wherein the metal plate has a thickness ranging from 100 to 800 mm.

11. A method according to any one of the preceding claims, wherein the metal plate is an aluminum plate.