FR2876788A1 - Performance evaluation unit for physical unit e.g. shape, measuring tool, has blocks comprising holes, where each block is assembled with support piece and/or another block in removable and independent manner in different locations of piece - Google Patents

Abstract

The evaluation unit (1) has blocks (4, 5, 6) respectively comprising holes (3a, 3b, 3c) of predetermined dimension and geometric form. Each block is adapted to be assembled with a support piece (2) and/or with another block, in a removable and independent manner and in different locations of the piece. The piece and/or blocks are formed of honeycomb structure made of material having a low thermal expansion coefficient. An independent claim is also included for a method for evaluation of performance of a physical unit measurement tool.

Description

AVERAGE MEASUREMENT OF MEASUREMENT TOOL PERFORMANCE EVALUATION

  The present invention relates generally to the field of measurement and in particular the field of evaluation of the performance of measurement tools for, for example, to allow calibration.

  More particularly, the invention relates to a means for evaluating the performance of tools for measuring physical quantities such as dimensions, comprising: a support piece; - Geometric shapes of predetermined and known dimensions able to be measured by a measuring tool.

  The invention also relates to a method for evaluating the performance of a tool for measuring physical quantities.

  It is frequently necessary to evaluate the performance of measurement tools such as tools for measuring dimensions, shapes, or other physical quantities. Such measuring tools can be three-dimensional measuring machines, and can use laser, photogrammetric, contact measurement techniques. Commonly such measuring tools are controlled by performing with them measures on performance evaluation means also called standards or references.

  The measurements thus obtained can be compared with predetermined and known measurement values related to the measured evaluation means.

  Classically a means of measuring tool evaluation is a notched ruler made of steel, rack-shaped whose notches are repetitive. Such a rule is long and heavy because it is made of steel which makes it difficult to handle.

  This rule also has the disadvantage of being dedicated to a type of measurement related to the repetitive form of the notches and does not allow to easily vary the type of possible measurements. Such a rule does not make it possible to evaluate the performance of a measuring tool with regard to the measurements made on pieces of complex shapes such as vehicle bodies. On the other hand, such a rule does not make it possible to change the means of evaluation according to the type of measurement to be evaluated.

  It would be necessary to allow an evaluation of measurement tools that can be scalable according to the needs related to the actual use of the measurement tool.

  In this context, the purpose of the present invention is to propose a means of evaluating the performance of measurement tools making it possible to carry out various measurement evaluations, these evaluations being able to evolve according to the needs of the user.

  To this end, the means for evaluating the performance of measurement tools of the invention, moreover in accordance with the generic definition given in the preamble defined above, is essentially characterized in that the geometric shapes are formed at the surface of several separate blocks, each block being adapted to be removably assembled to the support part and / or another block.

  With this evaluation means it is possible to perform a measurement type on one block, another type of measurement on another block and possibly a measurement using two measurement points located respectively on two different blocks. On the other hand, the fact that these blocks are removable makes it possible to modify the evaluation means by adding, removing or replacing one or more blocks by other blocks.

  For example, it is possible for each block to be assembled independently with said support piece. In this way a block can be mounted or removed from its support without necessarily having to disassemble the other blocks of the support.

  It is also possible to ensure that each block is adapted to be assembled, removably, at various locations of said support thereby forming a modular evaluation means.

  The possibility of assembling the same block in several locations of the support involves a standardization of the block assembly means available on the support, which has the advantage of increasing the modularity and scalability of the evaluation means which is therefore, particularly adaptable to the chosen evaluation constraints.

  It is also possible to ensure that the support and / or the blocks are in one or more materials (x) having a thermal expansion coefficient (s) of less than 12 * 10 -6K-1 and preferentially lower (s) to 8 * 10-6K-1, this or these material (s) may be a composite material comprising carbon fibers, and preferably a honeycomb structure comprising carbon.

  The coefficients of thermal expansion of the material or materials of the blocks and support are preferably chosen to be low in comparison with those of metals usually used in the field of metrology, such as steels whose expansion coefficient is about 12 * 10. -6K-1 and titanium whose coefficient of thermal expansion is about 8 * 10-6K-1. Ideally a honeycomb structure made of a composite material containing carbon is used to form the support and / or the blocks . Such a structure has the advantage of being light, not deformable by thermal expansion effect and relatively invariant in size over time.

  The fact that the evaluation means is insensitive to thermal expansion makes it possible to avoid applying certain correction coefficients of the measurements related to the temperature of the evaluation means. Such an evaluation means could ideally be stored in areas with little or no air conditioning without the need to wear it at a given temperature before having to perform a calibration measurement with this means.

  It is also possible for each block 25 to have a lower flat surface complementary to a positioning surface formed on the support and on which the block is placed.

  Such a surface makes it possible to assemble a block on the support by knowing the proper dispersions of the assembly. Such complementary lower and positioning surfaces in particular make it possible to know the theoretical value of the positioning dispersion existing between each block and the support, and by extension between two blocks assembled on the support.

  There is also provided a method for evaluating the performance of a tool for measuring physical quantities, characterized in that it comprises: at least one measurement step, using said measuring tool, of at least one predetermined physical quantity belonging to a performance evaluation means according to the invention, and at least one step of comparing the result of this measurement with the predetermined physical quantity of the evaluation means.

  This method using the evaluation means according to the invention makes it possible to evaluate the dispersion of a measurement linked to a particular measurement tool and to a particular measurement condition whose difficulty varies as a function of the modular blocks used.

  Other features and advantages of the invention will emerge clearly from the description which is given below, by way of indication and in no way limiting, with reference to the accompanying drawings, in which: FIG. 1 represents a perspective view of a means for evaluating the performance of measurement tools according to the invention.

  As previously announced, the invention relates to a means 1 for evaluating the performance of measuring tools 30 of physical quantities such as dimensions of length, thickness, diameter, color of the surface of the reflection of the material. .

  A support piece 2 comprising this means is formed by a rectangular composite material plate having a lower seating plane 11 adapted to stably maintain said evaluation means, relative to a measurement table (such as a marble table). a three-dimensional measuring machine) on which the evaluation means 1 is placed.

  This support 2 is not very sensitive to expansion because it is carbon. On the other hand, this support 2 has four calibration reference points which can be its lateral faces or elements fixed to the support 2 such as palpable centering balls.

  Three blocks 4, 5, 6 are assembled removably side by side on the support by unrepresented assemblies which may, for example, be of the conical assembly type, cylindrical centering assembly and point support.

  Each block has its own assembly means cooperating with a complementary standard assembly means installed on the support. With such an assembly the expansion proper to a block does not influence the neighboring blocks which reduces the disturbances of measurements by the effect of expansion of a block. On the other hand the fact that each block is assembled independently on the support 1 allows to vary at will the measurement test.

  These blocks 4, 5, 6 have the general shape of cubes of about 10 centimeters of sides.

  Geometric shapes 3a, 3b, 3c are respectively formed on the surface of a first, second and third block 4, 5, 6.

  These geometrical shapes 3a, 3b, 3c have predetermined and known dimensions and are able to be measured by a measuring tool.

  These geometrical shapes 3a, 3b, 3c are circular holes such as the hole 3d of the first block 4 and / or oblong holes 3a and / or forms representative of a vehicle side 10, 3c. These shapes can also be square holes, screws, nuts, studs, block ledges, crimps, curves.

  Preferentially, these forms correspond to actual forms existing on a vehicle body, thus making it possible to reproduce all the dimensions to be measured on a vehicle body and to evaluate the tools for measuring vehicles with respect to forms that are close to reality. industrial products.

  Each of the shapes 3a, 3b, 3c, 3d may be, for example, made in or on an insert assembled on a block at insert receiving sites.

  This allows to adapt on the same block a multitude of forms by simple exchange of inserts on the block.

  External profiles 9 such as that carried by the first block 4 may also constitute geometric shapes. The outer profile 9 is formed outgrowth of the block and has a particular predefined thickness e. This profile makes it possible to evaluate the ability of a measuring means to measure one or more predefined and known thicknesses.

  Thicknesses representative of thicknesses of body panels can thus be measured.

  At least one of the blocks 4, 5, 6 has wave reflection characteristics such as predefined light or electromagnetic waves, and substantially identical to material wave reflection characteristics such as automotive body sheet. .

  For example, gray blocks will be chosen which is a color close to the color of the raw sheet. Thus, it is possible to evaluate the quality of measurements made by different measuring tools such as light wave reflection measurement tools in conditions close to reality, taking into account the reflection characteristics specific to the material of the invention. constituent of the form or its surface state.

  It is also possible to provide that the shapes are made of different materials if differential reflection measurements are to be made.

  The fact that the blocks 4, 5, 6 are different from each other allows using a single evaluation means to perform several measurements on several interchangeable blocks. It is possible to make each block have a particular shape characteristic to which a particular measurement difficulty corresponds. The assembly of different blocks on the same evaluation means makes it possible to vary, in a modular manner, the number and the difficulty of the measurements authorized by this evaluation means.

  By means of performance evaluation of a measuring tool according to the invention, it is possible to evaluate the real uncertainty of a measuring tool, and this by testing it in conditions close to reality.

Claims (10)

  A method for evaluating (1) the performance of physical size measurement tools such as dimensions, comprising: a support piece (2); geometric shapes (3a, 3b, 3c) of predetermined and known dimensions that can be measured by a measuring tool, characterized in that the geometrical shapes (3a, 3b, 3c) are formed on the surface of several distinct blocks ( 4, 5, 6), each block being adapted to be removably assembled to the support member (2) and / or to another block.   2. Evaluation means (1) according to claim 1, characterized in that each block (4, 5, 6) is independently assembled with said support piece (2).   3. Evaluation means (1) according to one of claims 1 or 2, characterized in that each block (4, 5, 6) is adapted to be assembled, removably, at various locations (A, B, C) of said support (2) thereby forming a modular evaluation means (1).   4. Evaluation means (1) according to one of claims 1 to 3, characterized in that the support (2) and / or the blocks (4, 5, 6) are in one or more materials (x) having one or more coefficient (s) of thermal expansion less than 12 * 10 -6K-1 and preferably less than 8 * 10-6K-1, this or these material (s) possibly being a composite material comprising carbon fibers, and preferably a nest structure. bee comprising carbon.   5. evaluation means (1) according to any one of claims 1 to 4, characterized in that each block (4, 5, 6) comprises a lower flat surface 7 complementary to a positioning surface (8) formed on the support (1) and on which the block (4, 5, 6) is placed.   6. Evaluation means (1) according to any one of claims 1 to 5, characterized in that some of said geometric shapes (3a, 3b, 3c) are circular holes and / or oblong holes (3a) and / or representative forms of a vehicle side (10, 3c).   7. Evaluation means (1) according to claim 6, characterized in that it comprises a plurality of external profiles (9) each having a particular predefined thickness (e) thus making it possible to evaluate the aptitude of a measuring means to measure various thicknesses.   8. Evaluation means (1) according to any one of claims 1 to 7, characterized in that at least one of the blocks (3a, 3b, 3c) has wave reflection characteristics such as waves predefined light or electromagnetic, and substantially identical to material wave reflection characteristics such as a car body sheet.   9. Evaluation means (1) according to any one of claims 1 to 8, characterized in that said blocks (3a, 3b, 3c) are different from each other.   10. A method for evaluating the performance of a tool for measuring physical quantities, characterized in that it comprises: at least one step of measuring, using said measuring tool, at least one predetermined physical quantity belonging to an evaluation means (1) according to any one of claims 1 to 9, and at least one step of comparing the result of this measurement with the predetermined physical quantity of the evaluation means (1).