Crack evolution measurement device, mounting plate and corresponding method

Abstract

A device is proposed for measuring the evolution of a crack present on a structure. The device comprises a measuring gauge (1) having a main body (10) from which extend two measuring arms (11, 12) movable relative to each other and each equipped with a positioning pin (13, 14), and a set of mounting plates (2, 3) intended to be fixed on either side of the crack and into which the positioning pins (13, 14) of the gauge are engaged. The pins are each mounted for rotation at one end of one of the measuring arms about at least one axis of rotation, the pins and the plates being configured to allow reversible locking of the positioning pins in the associated plates. Figure 1

Description

Title of the invention: Device for measuring the evolution of cracks, corresponding fixing plate and method Technical field

[0001] The invention relates to the field of metrology, and more particularly to the field of structural instrumentation.

[0002] The invention relates more specifically to a technique for measuring the evolution of a distance between two points of a structure. Such a technique is mainly used to follow the evolution of a crack, that is to say the evolution between two points located on either side of the crack (a first point being located in the vicinity of one lip thereof and a second point being located in the vicinity of the opposite lip thereof).

[0003] This type of technique finds applications particularly, but not exclusively, in the field of construction and civil engineering where the materials used are subjected to severe testing. The environment, the effects of time and the various stresses to which they may be subject affect their original properties, leading to structural disorders whose evolution it may be important to monitor.

[0004] Here, the term "disorder" means an abnormal deformation of a structure. A disorder is, for example, constituted by a crack, a misalignment, a shear creating relative displacements in at least one direction of two parts of the structure normally occupying a reference position. The term "structure" means a solid element or an assembly of solid elements of an artificial or natural type. Without being exhaustive, a structure is, for example, constituted by a wall, a facade, a wall of a building, an assembly of beams forming a framework, a bridge deck, an element of a work of art or a building made of masonry or concrete, or a natural wall such as a rock, a cliff, a tree trunk, etc. Technological background

[0005] In the remainder of this document, we will focus more particularly on describing the problem existing in the field of civil engineering with which the inventors of the present invention were confronted, in particular for measuring the evolution of cracks on a building structure. The invention is of course not limited to this particular context of application, but is of interest for any technique for measuring the evolution of the displacement between at least two points of a structure having to face a similar or similar problem.

[0006] It is common for civil works and constructions to require occasional or periodic observation. Implement actions to stabilize, or even to secure the structure concerned, requires having factual and reliable information on the nature of the disorder observed, and measuring the evolution of this disorder over time in order to know the trend, identify the cause and define the type of repair to be considered.

[0007] In the state of the art, there are different types of measuring gauges, each corresponding to a particular type of disorder. A measuring gauge is an instrument configured to deliver measurements representative of the spacing of a crack. Such measurements can be carried out periodically over time in order to identify the type and monitor the observed disorder. These measurements can be carried out on a single axis or on several axes, and in a single plane or on several distinct planes (this is the case, for example, when a crack is present at the junction between two perpendicular work planes and it is desired to follow the evolution of this crack in the vicinity of this closed angle). In order to avoid human errors in reading and interpretation, more and more measuring gauges are equipped with a display screen and an on-board microprocessor to allow direct and precise digital reading of the measurements.

[0008] The solution described in patent document FR2965612 is based on the use of a measuring gauge carrying a measuring member and a target, the measuring gauge and the target being fixed on either side of the crack to be studied. The measuring gauge is placed on its fixing plate so that the measuring member can cooperate with the target surface of said target. The measuring gauge is further provided with a direct reading screen to indicate the measured distance between the target surface of the target and the support surface of the plate. However, such a solution requires the use of specific elements, in particular a target in the form of a square. It also requires the gauge to be held manually during the measurement operation, which induces a dependence of the operator on the quality of the measurement carried out. The precision and repeatability of the measurements are therefore not optimal with such a solution.Furthermore, it is limited to measurement configurations with flat surfaces: it is therefore not compatible with certain types of disorder (miscropping or crack present at a closed angle). Finally, it is not possible to carry out measurements for cracks whose spacing is greater than a certain distance, typically of the order of 5 centimeters.

[0009] In order to accurately assess the evolution of cracks over time, some state-of-the-art devices have been designed to remain in place for long periods (several weeks, or even several months typically). However, such an approach is not optimal since it requires a design adapted to the device's environment, which is more or less expensive and complex to implement. In particular, the device and its components must be designed sufficiently robust to withstand climatic variations and possible bad weather (and thus guarantee stability of measurements), and configured to be completely autonomous for long periods during which no recharging or maintenance can be ensured.

[0010] There is therefore a real need to propose a device for measuring crack development which is versatile, of increased precision, and which can guarantee the repeatability of measurements over time, or even improve their reproducibility. Summary of the invention

[0011] In a particular embodiment of the invention, a device is proposed for measuring the evolution of the distance between at least two points of a structure. The device comprises a set of fixing plates each intended to be fixed to one of the points of the structure and a measuring gauge having a main body from which extend two measuring arms movable relative to each other. The measuring arms are each provided with a positioning pin intended to be secured to one of the fixing plates of said set of plates. The device according to the invention is characterized by the fact that: - the positioning pins are each mounted so as to be rotatable at one end of one of the measuring arms around at least one axis of rotation so as to make each positioning pin rotatable along said at least one axis of rotation relative to the measuring arm associated with it, and - the positioning pins and the fixing plates are configured to allow reversible attachment of the positioning pins in the associated plates.

[0012] Thus, the present invention proposes to provide the measuring device with an articulated system for securing to plates fixed to the structure, making it versatile and freely configurable. Thus, unlike traditional devices, it is possible to use the same device regardless of the measurement configuration (planar configuration, closed angle configuration, etc.).

[0013] According to a first implementation, the set of plates is made up of two fixing plates for carrying out single-axis measurements (in a single direction). In this case, a first plate is previously fixed to a first point of the structure in which one of the positioning pins of the gauge engages, and a second plate is previously fixed to a second point of the structure in which the other positioning pin of the gauge engages.

[0014] According to a second implementation, the set of plates is made up of three fixing plates for carrying out bi-axis measurements (in two directions). In this case, a first, second and third plate are previously fixed respectively on a first, second and third point of the structure, the first and second plates being intended to receive the positioning pins of the gauge for the first measurement and the first and third plates being intended to receive the positioning pins of the gauge for the second measurement (the first plate being used in common for both measurements). The second and third plates being intended to receive the positioning pins of the gauge for a reference measurement.

[0015] Thus, the present invention makes the device more convenient to handle, while allowing a wide variety of measurements of the distance between at least two points of a structure, for example chosen on either side of a crack or deformation.

[0016] The positioning pins are secured in the associated plates using reversible securing means belonging to the group comprising: magnetic securing means, securing means by clipping, by snap-fastening, securing means by pinning. This list is not exhaustive.

[0017] According to a particular aspect of the invention, the measuring arms are composed of an arm movable in translation and a fixed arm extending along a measuring axis, the positioning pin associated with the movable arm being mounted movable in rotation about at least one axis of rotation orthogonal to the measuring axis, and the positioning pin associated with the fixed arm being mounted movable in rotation about a first axis of rotation orthogonal to the measuring axis and a second axis of rotation coaxial with the measuring axis. Such an articulation system makes the positioning of the gauge on the plates easy and precise.

[0018] According to an even more advantageous characteristic, the positioning pin associated with the mobile arm can be mounted mobile in rotation around two axes of rotation, as for the other pin of the gauge.

[0019] According to a particular implementation, the female securing housing comprises a plurality of lateral tabs elastically deformable between a locked position and an unlocked position, the unlocked position being taken momentarily during the introduction of the male securing portion into the female securing housing.

[0020] According to a particular configuration, the male securing portion comprises a temporary displacement member and a locking member, and the lateral tabs have in the vicinity of their free end a protrusion forming a projection, the temporary displacement member being shaped to temporarily act on the projections of the lateral tabs to temporarily deform the lateral tabs during the introduction of the male securing portion into the housing of female connection. "Locking" means keeping the pin in position in the plate.

[0021] According to a particular implementation, the fixing plates are each provided with a plurality of lateral grooves. This is a technical solution facilitating the development of injection tools for the manufacture of the plates.

[0022] According to a particular aspect of the invention, the fixing plates have a base in which a central through hole is provided intended to accommodate an element for fixing to the structure, a plurality of through openings distributed around the periphery of said base and a plurality of contact pins distributed over a contact face of said base.

[0023] In another particular embodiment of the invention, a fixing plate is proposed intended to be part of a set of fixing plates included in the aforementioned measuring device (in any one of its embodiments).

[0024] In another particular embodiment of the invention, a method is proposed for measuring the evolution of the distance between at least two points of a structure by means of a measuring gauge, the measuring gauge being provided with two measuring arms movable relative to each other and positioning pins each mounted movable in rotation at one end of one of the measuring arms around at least one axis of rotation. Such a method is characterized by the fact that it implements the following steps:

[0025] - installation of the measuring gauge by securing the positioning pins in a first pair of fixing plates of a set of fixing plates previously fixed on the structure, a first plate being fixed on a first point of the structure and a second plate being fixed on a second point of the structure

[0026] - measuring the distance between said first and second points of the structure.

[0027] Thus, the present invention offers a simple and convenient implementation mode for the operator, whatever the measurement configuration. Indeed, the fixing plates of the first pair can be fixed on the same plane or on two separate planes of the structure. In addition, the installation and measurement steps can be repeated to characterize the evolution of the distance separating the first and second points over a given time interval.

[0028] According to a particular aspect of the method, the step of placing the measuring gauge is also carried out for a second pair of fixing plates of said set previously fixed on the structure, the second pair comprising a third fixing plate fixed on a third point of the structure and said first fixing plate fixed on the first point, the measuring step is also carried out to measure the distance between said first and third points of the structure and the distance between said second and third points of the structure. Figures

[0029] Other characteristics and advantages of the invention will appear more clearly on reading the following description of a preferred embodiment, given as a simple illustrative and non-limiting example, and the appended drawings, among which:

[0030] [Fig-1] schematically represents a device for measuring the evolution of a crack according to a particular embodiment of the invention;

[0031] [Fig.2] is a side view illustrating the structural details of a posi pawn operation according to a first implementation of the invention;

[0032] [Fig.3] is a perspective view of the positioning pin illustrated in [Fig.2];

[0033] [Fig.4] is a perspective view illustrating the structural details of a turntable fixing according to a first implementation of the invention;

[0034] [Fig.5] is a perspective view of the underside of the mounting plate illustrated in [Fig.4] ;

[0035] [Fig.6] is a detailed view of an elastic side tab provided in the plate illustrated in figures 4 and 5;

[0036] [Fig.7] and [Fig.8] illustrate examples of possible orientation of the posi pins operation of the measuring gauge according to the invention;

[0037] [Fig.9] represents the measuring device according to the invention in a configuration of closed angle measurement;

[0038] [Fig. 10] is a perspective view illustrating a positioning pin according to a second implementation of the invention;

[0039] [Fig. 11] is a perspective view illustrating a fixing plate according to a second implementation of the invention;

[0040] [Fig. 12] is a perspective view illustrating a positioning pin according to a third implementation of the invention;

[0041] [Fig. 13] is a perspective view illustrating a fixing plate according to a third implementation of the invention;

[0042] [Fig. 14] illustrates an example of a calibration plate used for zeroing the device according to the invention;

[0043] [Fig. 15] represents an example of a template for installing plates in a single-axis measurement configuration;

[0044] [Fig. 16] represents an example of a bi-axis measurement configuration requiring the use of a trio of fixing plates according to the invention;

[0045] [Fig. 17] represents an example of a template for installing plates in a bi-axis measurement configuration;

[0046] [Fig. 18] a perspective view illustrating a positioning pin according to a fourth implementation of the invention;

[0047] [Fig. 19] is a perspective view illustrating a fixing plate according to a fourth implementation of the invention. Detailed description of the invention

[0048] In the figures of this document, identical elements are designated by the same numerical reference.

[0049] The general principle of the invention is based on the use of a system of articulated solidarization on a structure offering a versatile and reliable measuring device (repeatability, reproducibility) over time.

[0050] In the remainder of this document, the invention is more particularly described in the context of monitoring a crack present on a building structure (wall, floor or ceiling). Indeed, it appears that the field of construction is particularly affected by this phenomenon, which can jeopardize the stability of buildings or structures, or even compromise the safety of its occupants. Observing cracks makes it possible to measure their possible evolution over time and to intervene accordingly. The invention is of course not limited to this particular field of application, but is applicable to any sector or application requiring a measuring device for the effective monitoring of the evolution of a structural disorder and / or movements between two points of a structure.

[0051] Single-axis measurement (pair of plates)

[0052] Two particular configurations of the device are proposed: a so-called "planar" measurement configuration allowing measurement of the evolution of cracks located in a single plane of the structure and a so-called "closed angle" measurement configuration allowing measurement of the evolution of cracks located in a closed angle (generally at the joint between two planes of the structure). The first configuration is described below in relation to [Fig. 1], while the second configuration is described further on in relation to [Fig. 9].

[0053] We now present, in relation to Figures 1 to 5, a device for measuring the evolution of a crack according to a particular embodiment of the invention.

[0054] As illustrated in [Fig.l], the device 100 comprises a measuring gauge 1 having a main body 10 from which extend two measuring arms 11-12 movable relative to each other. The measuring arm 11 is a fixed arm, integral with the body 10, extending along the measuring axis X, while the measuring arm 12 is an arm mounted movable in translation along the measuring axis X (a telescopic arm or sliding arm or equivalent member). The measuring arms 11-12 are respectively provided with positioning pins 13-14 making it possible to position the measuring gauge 1 on either side of the crack F.

[0055] The main body 10 of the gauge 1 comprises a position sensor (not shown) connected to the measuring arms 11-12, a direct digital reading display screen 15, an autonomous power supply source of electrical energy (not shown). The gauge 1 is also equipped with a processing unit (or microcontroller) electrically connected to these different elements for control purposes. The gauge 1 is configured to measure, by means of the sensor, the relative displacement of the movable arm with respect to the fixed arm with a resolution of the order of 0.01 mm and deliver data representative of the spacing of the crack F.

[0056] The device 100 further comprises a set of fixing plates 2-3 fixed to the structure on either side of the crack F and in which the positioning pins 13-14 of the gauge 1 engage respectively. The fixing plates are fixed to the structure by means of a conventional fixing system of the type comprising a dowel and a screw for example.

[0057] The crack F illustrated here is located on the same plane of the structure. In this “planar” measurement configuration, it should be noted that the positioning pins 13 and 14 of the gauge are arranged parallel to each other and both extend perpendicularly to their respective arms.

[0058] Advantageously, the positioning pins 13-14 are reversibly secured to the fixing plates 2-3 respectively. The principle of reversible securing of the pin to the plate is described in more detail below in relation to Figures 2 to 5. It allows, in particular, simple, rapid and precise installation of the gauge in the fixing plates fixed to the structure, as well as simple and rapid removal of the gauge from the fixing plates.

[0059] According to another advantageous characteristic of the invention, the positioning pins 13-14 are each mounted so as to be movable in rotation at the free end of one of the measuring arms around at least one axis of rotation, so as to make each positioning pin of the gauge 1 movable in rotation along the axis(es) of rotation concerned. The principle of articulation of the positioning pins to the measuring arms is detailed below in relation to FIGS. 7 and 8. It has the effect, in particular, of making the device much more versatile than the measuring devices of the state of the art.

[0060] For better readability of the figures, the mechanical axes of the positioning pins of the device are represented in dotted lines: XI, Y1 for the positioning pin of the fixed arm and Z2 for the positioning pin of the mobile arm.

[0061] As illustrated in Figures 7 and 8, the positioning pins 13-14 are articulated on the free end of the measuring arms 11-12 respectively, in the following manner:

[0062] - the positioning pin 13 associated with the fixed arm 11 is mounted to be mobile in rotation on the one hand around a first rotation axis Y1 orthogonal to the measurement axis X of the device and on the other hand around a second rotation axis XI coaxial with the measurement axis X,

[0063] - the positioning pin 14 associated with the movable arm 12 is mounted movable in rotation around a rotation axis Z2 orthogonal to the measurement axis X of the device (the two axes may or may not be intersecting depending on the embodiment chosen).

[0064] In this way, the articulation of the positioning pin 13 has two degrees of freedom allowing, on the one hand, freedom of rotation around the axis of rotation Yl, and on the other hand, freedom of rotation around the axis of rotation XI, thus making the pin 13 mobile in rotation at the end of the fixed arm 11 according to the axes of rotation Yl and XI. In the example illustrated in the figures, this mechanical connection between the pin 13 and the arm 11 is ensured by means of a double pivot connection. Any other mechanical member fulfilling this function, such as for example a finger ball joint, can of course be envisaged.

[0065] As for the positioning pin 14, the latter has a single degree of freedom in rotation around the axis of rotation Z2, thus making the pin 14 mobile in rotation at the end of the mobile arm 11 along the axis of rotation Z2. This mechanical connection between the pin 14 and the arm 12 is ensured by means of a simple pivot connection.

[0066] Alternatively, the positioning pin 14 can also be mounted so as to be able to rotate about two axes of rotation, these two axes being orthogonal to the measuring axis X of the device. Such a configuration allows the positioning pin 14, just like the pin 13, to be articulated at the end of the movable arm 12 with two degrees of freedom (in addition to the sliding movement of the movable arm along the X axis).

[0067] It is this combination of connections, as well as their positioning relative to each other, which makes it possible to guarantee the isostatism of the device whatever the initial orientation of the plates, while guaranteeing a repeatable measurement.

[0068] The principle of reversible pin-on-plate attachment according to a first implementation of the invention is described below, in relation to Figures 2-3 and 4-5. Figures 2-3 illustrate two particular views of the positioning pin 13 of gauge 1 described above and Figures 4-5 illustrate two particular views of the fixing plate 2 intended to receive the positioning pin 13 by clipping. Since the positioning pins 13 and 14 of gauge 1 are identical, as are the fixing plates 2 and 3, only the technical details of the pin 13 and its associated fixing plate 2 are set out here, the technical details of the pin 14 and its associated fixing plate 3 being able to be repeated identically (except for the configuration of articulation to the mobile arm). Positioning pawn

[0069] The positioning pin 13 according to the invention comprises an upper portion 130, a lower portion 132 and a central portion 131, arranged between the upper and lower portions. The lower portion acts as a centering and securing element. It is called the “male securing element” in the remainder of the description. The portions 130, 131 and 132 are generally cylindrical in shape, each having a different diameter. The central portion 131 has a larger diameter than that of the lower portion 132 so as to define a projecting surface 131-1 serving as a stop when inserting the part.The upper portion 130 and the fixed arm 11 are secured by an L-shaped connecting yoke 15 in which two perpendicular through bores are provided: the first bore is arranged to receive the rotation axis Y1 itself cooperating with the upper portion 130, and the second bore is arranged to receive the rotation axis XI itself cooperating with the fixed arm 11, so as to form the double pivot connection discussed above for the pin 13 (similar to a ball joint with finger).

[0070] According to this first implementation, the male securing portion 132 is composed of a centering and temporary displacement member 132-2, arranged at the free end thereof, and a locking member 132-1 formed between the displacement member 132-2 and the central portion 131. It further comprises a central clearance. Mounting plate

[0071] The fixing plate 2 according to the invention comprises a body of overall cylindrical shape with a central recess defining a base 25 from which there is a peripheral side wall 22, delimiting a female securing housing 21. The female securing housing 21 is intended to cooperate with the male securing portion 132 of the positioning pin. The side wall 22 has a thickness defining a flat upper surface, of annular shape, intended to serve as a flat support for the projecting surface 131-1 of the central portion 131. A plurality of centering grooves (six in this case), referenced 24a to 24f, regularly distributed on the side wall 22 of the plate and intended to cooperate with the male portion 132, is also provided to guarantee the centering of the pin in the plate during its assembly and the repeatability of this operation.The base 25 is provided with a central through hole intended to receive a fixing element to the structure (not shown), such as a fixing screw for example, to securely fix the plate to the structure. The female housing 21 comprises a plurality of lateral tabs, in this case three, referenced 24a, 24b, 24c, regularly arranged at the level of the lateral wall 22 of the plate. Each lateral tab acts in a way like a “fixing clip”. More precisely, each lateral tab is shaped to be elastically deformable between a locked position and an unlocked position, the unlocked position being taken momentarily. tangently when introducing the male portion 132 into the female housing 22 and when removing the male portion 132 from the female housing 22. The fixing plate 2 further comprises a plurality of through openings (24-1, 24-2, 24-3) regularly distributed around the periphery of the base 25 to evacuate water from the plates during bad weather and a plurality of contact pins (26) regularly distributed on the contact face of the base 25 intended to be transferred onto the structure to increase the adhesion of the plate to the surface of the structure and thus prevent it from sliding on the structure.

[0072] According to this first implementation, the lateral tabs of the plate are each formed by a U-shaped cutout on the surface of the side wall 22 so as to give them a capacity for elastic deformation substantially perpendicular to the surface of the side wall 22 when the male portion 132 of the positioning pin is introduced into the female housing 20 of the plate. To do this, as illustrated in [Fig. 6], the lateral tab 23a is U-shaped in the lying position, which extends parallel to the base 25 following the curve of the side wall. The lateral tab 23a also has, in the vicinity of its free end, a tooth 230, extending parallel to the base 25, and shaped so as to project from the side wall towards the center of the plate. The other two side tabs 23b and 23c are identical to the side tab 23a and perform the same function. Securing the pin-plate assembly

[0073] To measure the spacing of the crack F along the X axis, the operator first mounts the gauge 1 on the fixing plates 2 and 3 previously fixed to the structure on either side of the figure F.

[0074] The example of securing the pin 13 in the plate 2 is described below.

[0075] The operator proceeds to position the gauge 1 so as to place the axis of the pin 13 in the axis of the corresponding plate 2, then proceeds to insert it. The introduction of the male portion 132 of the pin 13 inside the female housing 21 of the plate causes the temporary displacement member 132-2 to temporarily act on the teeth of the lateral tabs 23a to 23c to momentarily deform the lateral tabs (this is then referred to as the unlocked position), until the projecting surface 131-1 reaches the abutment of the flat support of the fixing plate (this is then referred to as the locked position). The particular shape of the tooth allows the surface 131-1 to be pressed against the surface 22 with permanent tension. The tooth is therefore always in contact with the conical surface connecting the members 132-2 and 132-1. The centering of pin 13 in the female housing of the plate is ensured by the centering grooves when it is introduced.The positioning pin 13 is thus “locked” to the fixing plate 2 intended for it.

[0076] Thus, the male portion 132 fulfills two functions here: clipping on the one hand and short centering in the plate on the other hand (thanks to the member 132-2 which ensures this second function by cooperating with the six gadroons of the plate). It is this centering function, coupled with the flat support (overhanging surface 131-1 in contact with the upper annular surface 22) which guarantees the repeatability of the positioning of the pins.

[0077] The same securing operation is carried out with the positioning pin 14 and its associated fixing plate 2. The two securing operations can be carried out simultaneously or sequentially. The concave shape of the pins makes them easier to grip. In the locked position, each pin is therefore pressed against the flat support and the base of the fixing plate, thus holding the measuring gauge 1 securely in place without the need to manually hold the gauge for measurement. Such a mechanism allows easy and precise securing of the gauge to the structure. It should also be noted that the device according to the invention uses a set of identical plates, which makes it possible, on an industrial scale, to manufacture only one type of plates (and associated positioning pins), significantly reducing the manufacturing cost of the constituent parts of the device.The present invention therefore presents a definite advantage in terms of assembly ergonomics and manufacturing cost.

[0078] Once the measuring gauge 1 is secured to the plates 2 and 3 and held in position thanks to the elastic tabs, a measurement (or a series of measurements) of the spacing of the figure F along the X axis is carried out. The pin-plate fastening system according to the invention, as described above, thus offers the possibility of autonomously holding the measuring gauge without an operator. By eliminating the influence of the operator, the measurements carried out with the device of the invention are therefore more precise than with the devices of the state of the art.

[0079] Once the measurement (or series of measurements) is complete, the operator removes the measuring gauge 1 from the fixing plates 2-3. Other single-axis measurements may be carried out, punctually or periodically over time, in order to evaluate the evolution of the crack F over time (comparison and estimation of the difference between the values ​​recorded over time).

[0080] It will be noted that the particular shape of the lateral tabs combined with the presence of the centering grooves ensures the repeatability of the measurements over time without influence from the operator. Separation of the pin-plate assembly

[0081] For detachment, the operator removes the pins by applying sufficient removal force along the pin / plate axis. To avoid any movement of the plates relative to the surface on which they are fixed, the operator can hold the plate by the periphery, and use the concave shape 131 of the pin to pull the latter. It is also possible to proceed with a simultaneous removal of the measuring gauge by pulling directly on the central body of the gauge, separating the two pins at the same time, although this approach is less recommended.

[0082] The fixing plates 2-3 according to the invention typically have an outside diameter of 33 mm, for 8 mm in height, and the housing 21 has a diameter of 22 mm for 6 mm in height. The centering is achieved by the inscribed circle defined by the gadroons at 21.80 mm. As for the positioning pin 13, the upper 130, central 131, lower 132-1 and lower 132-2 portions have a diameter of 14, 32, 20.3 and 21.7 mm respectively. Thus, to guarantee the repeatability of the positioning of the measuring gauge, the positioning pins use a flat support over a circumference of 27.5 mm. The position along the axis O of the member 132-2 and the flatness of the surfaces 131-1 and 22 must be as precise as possible. To obtain the isostatism of the system, the pin-plate assembly is shaped to define a short centering and a plane support, which removes 5 degrees of freedom (3 in translation and 2 in rotation).The last degree of rotational freedom is eliminated by the second pin-plate assembly, which orients the assembly along the axis formed by the 2 plates. In the example illustrated here, the 21.7 mm diameter of the 132-2 bead is only 0.8 mm high to ensure the feasibility of short centering.

[0083] This is of course an illustrative example and many other dimensions can be envisaged depending on the desired technical needs.

[0084] We now present, in relation to [Fig. 9], an example of use of the device 100 in a closed angle measurement configuration. This particular measurement configuration is adopted in the case where a crack appears between two adjoining surfaces at a closed angle or in the vicinity of the joint between two adjoining surfaces, such as the crack F' for example illustrated in the figure. In such a configuration, the fixing plates 2-3 are each fixed on a separate surface of the structure, the positioning pins 13-14 of the measuring gauge 1 being articulated so as to cooperate respectively with the associated plates 2-3. In the example illustrated here, the positioning pin 13 extends perpendicular to the fixed arm 11 and the positioning pin 14 extends in the axis of the movable arm 11, that is to say in the measurement axis X.Thus, unlike the “planar” configuration where the positioning pins 13-14 are parallel, in the closed angle configuration, the positioning pins 13-14 are perpendicular to each other. This illustration of the device in this second measuring configuration shows the versatility of the device according to the invention. Indeed, thanks to the system of articulation of the positioning pins which makes each positioning pin mobile in rotation along at least one axis of rotation relative to the measuring arm associated with it, it is possible to adapt the measuring device to different measuring configurations. The operations of solida- . The measurement, separation and disengagement techniques described above in relation to the “planar” measurement configuration can be transposed to the present closed angle configuration.

[0085] It will be noted that the fixing plate 2 comprises an identification plate on which is written an identification relating to the pair of plates 2-3, for example a QR code and / or an alphanumeric code, for the purpose of monitoring the measurements.

[0086] We now present, in relation to figures 10 and 11, a first variant of implementation of the pin-plate assembly according to the invention.

[0087] In this variant, the positioning pin 13' comprises an upper portion 130' in the form of a hinge lug, a lower portion 132', called the male securing portion, and a central portion 131', arranged between the upper and lower portions. The portions 131' and 132' are of generally cylindrical shape and have different diameters. The central portion 131' has a larger diameter than that of the lower portion 132' so as to define an overhanging surface 131-1' serving as a stop when inserting the part into the plate. The male securing portion 132' is composed of a temporary displacement member 132-2', of cylindrical shape, arranged at the free end thereof, and of a locking member 132-1', of cylindrical shape and of diameter smaller than that of the member 132-2', formed between the displacement member 132-2' and the central portion 131'.In this variant, the locking member 132-1' is in the form of a groove, unlike the positioning pin 13 where the locking member 132-1 is in the form of a clearance.

[0088] The corresponding fixing plate 2', for its part, differs from the fixing plate 2, in that the elastic lateral tabs 22a', 22b', 22c' are each formed by an inverted U-shaped cutout on the surface of the side wall and each have at its free end a tooth 230' projecting relative to the side wall of the plate in the direction of the central axis thereof. For simplicity, the lateral tabs 22a', 22b', 22c' are said to be oriented downwards. As for the fixing plate 2, the lateral tabs are designed to be elastically deformable between a locked position and an unlocked position, the unlocked position being taken momentarily when the male securing portion 132' is inserted into the female securing housing 21' and when the male securing portion 132' is removed from the female securing housing 21'.The principle of reversible joining explained above in relation to figures 2 to 5 also applies here, only the arrangement of the members of the pin and the lateral tabs of the plate differing from the previous implementation.

[0089] We now present, in relation to figures 12 and 13, a second variant of implementation of the pin-plate assembly according to the invention.

[0090] In this variant, the positioning pin 13” comprises an upper portion 130” in the form of a hinge ear, a lower portion 132”, called the male securing portion, and a central portion 131”, arranged between the upper and lower portions. The portions 131” and 132” are generally cylindrical in shape and have different diameters. The central portion 131” has a larger diameter than that of the lower portion 132” so as to define a projecting surface 131-1” serving as a stop when inserting the part into the plate. The male securing portion 132” is composed of a temporary displacement member 132-2”, of cylindrical shape, arranged at the free end thereof, and a locking member 132-1”, of cylindrical shape and of diameter smaller than that of the member 132-2”, formed between the displacement member 132-2” and the central portion 131”.In this variant, the locking member 132-1” is in the form of a groove formed between the displacement member 132-2' and a third member of cylindrical shape 132-3 and of diameter between the diameter of the displacement member 132-2' and that of the locking member 132-1”.

[0091] The corresponding fixing plate 2”, for its part, differs from the fixing plates 2 and 2' described above, in that the elastic lateral tabs 22a”, 22b”, 22c” are each formed by a U-shaped cutout in the surface of the side wall and each have at its free end a tooth 230'' projecting relative to the side wall of the plate in the direction of the central axis thereof. For simplicity, the lateral tabs 22a”, 22b”, 22c” are said to be oriented upwards. As for the fixing plate 2, the lateral tabs are designed to be elastically deformable between a locked position and an unlocked position, the unlocked position being taken momentarily when the male securing portion 132” is inserted into the female securing housing 21” and when the male securing portion 132' is removed from the female securing housing 21”.The principle of reversible joining explained above in relation to figures 2 to 5 also applies here, only the arrangement of the members of the pin and the lateral tabs of the plate differing from the implementations previously described.

[0092] As an alternative to the use of a tooth (in any of the preceding implementations), the lateral tabs according to the invention may be provided with a curved free end and / or a free end with an outgrowth so as to project relative to the lateral wall of the plate in the direction of the central axis thereof.

[0093] [Fig. 14] illustrates an example of a calibration plate 140 used for zeroing the device 100 before measurement. The calibration plate is made from a material with a low coefficient of thermal expansion. This makes it possible not to be dependent on the measuring instrument used or the operator in the event of change. [Fig. 15] shows an example of a 150 template for installing plates in a single-axis measurement configuration allowing precise fixing of the fixing plates on either side of the crack. The center distance between the holes helps with the optimal arrangement of the plates between coplanar surfaces. The distance between the holes and the edges helps with the optimal arrangement between perpendicular surfaces.

[0094] Bi-axis measurement (trio of stages)

[0095] Certain types of structural disorder require measurements to be taken in different directions. [Fig. 16] illustrates an example of a bi-axis measurement with the device of the invention. In comparison with the particular embodiment described above, a bi-axis measurement requires a set of three fixing plates 151, 152, 153. A measurement is taken along the axis A1, the measurement gauge then being positioned on the pair of plates 151-152 fixed on either side of the crack F”. A measurement is taken along the axis A2, the measurement gauge then being positioned on the pair of plates 151-153 fixed on either side of the crack F”. The plate 151 constitutes the common fixing plate, in other words the reference point for the measurements. A distance measurement is taken along axis A3 to determine the distance between plates 152-153 and to enable trigonometric calculation.

[0096] In practice, the operator first proceeds to fix the three plates 151, 152, 153 on the study structure using the installation template 170 illustrated in [Fig. 17]. Then, the operator places the measuring gauge 1 along the axis A3 by securing the positioning pins on the plates 152-153 to carry out the measurement along the axis A3. This measurement is a reference measurement used for trigonometric calculation. It is carried out only once for all at the start of the measurement campaign. Once the reference measurement has been made, the operator removes the gauge 1 from the plates 152-153 and places the gauge 1 along the axis A1 by securing the positioning pins to the first pair of plates 151-152 (in accordance with the principle described above in relation to Figures 1 to 5). Gauge 1 is held in place alone by the plates (i.e. without being held by the operator), then a measurement of the spacing of the crack F” along the axis Al is carried out.Once the first measurement has been carried out, the gauge 1 is removed from the fixing plates 151-152 by separating the positioning pins. The operator then places the measuring gauge 1 along the axis A2 by connecting the positioning pins to the second pair of plates 151-153. The operator carries out a measurement of the spacing of the crack F” along the axis A2. Once the second measurement has been carried out, the gauge is removed from the fixing plates 151-153 by separating the positioning pins. Said first and second measurements mentioned above may be repeated punctually or periodically over time, in order to monitor the evolution of the crack F” over time.

[0097] As a supplement, for the purpose of monitoring measurements, one of the fixing plates of the trio may include an identification plate on which is written a QR code and / or an alphanumeric code for identifying the trio of plates 151, 152, 153.

[0098] In view of the above, the measuring device according to the invention provides in particular, but not exclusively, the following advantages: allows direct reading of a value with a resolution of 0.01 mm, ensures repeatability of the positioning of the pins in the fixing plates, offers versatility in terms of measurement configuration, guarantees that the measuring gauge is held in its independent position, thus freeing it from the influence of the operator on the measurements.

[0099] A third variant implementation of the pin-plate assembly according to the invention is now presented in relation to Figures 18 and 19. This variant implementation is interesting from the point of view of its structural and functional simplicity. Unlike the previous implementations where the reversible joining is ensured by clips, the principle of reversible joining illustrated here is based on a magnetic connection.

[0100] More particularly, the positioning pin 18 comprises an upper portion 180 (for example in the form of an articulation ear connected to the fixed arm), a lower portion 182, called the male securing portion, and a central portion 181, arranged between the upper and lower portions. The central 181 and lower 182 portions are generally cylindrical in shape and have different diameters. The central portion 181 has a larger diameter than that of the lower portion 182 so as to define a projecting surface serving as a stop when the part is inserted into the plate. Compared to the previous variants, the male securing portion 182 is simplified by being composed of a single cylindrical member. The latter has a central clearance in which a magnetic attraction element is fixed (typically a block or a magnetic strip or a set of magnets).

[0101] As for the corresponding fixing plate 19, this does not include elastic lateral tabs unlike the previous variants (the clipping function is present in particular in the case of a plate made of rigid material (stainless steel for example for requirements in aggressive environments for example).

[0102] The plate 19 is composed of a body of overall cylindrical shape with a central recess defining a base 195 and a peripheral side wall 196 which extends from this base, delimiting a female securing housing 192. The body of the plate is made from a metallic material chosen to effectively attract said magnetic attraction element. This female securing housing 192 is shaped to cooperate with the male securing portion 182 of the positioning pin. The side wall 22 has a thickness defining a flat upper surface, of annular shape, intended to serve as a flat support for the surface de- bordering the central portion 181.

[0103] The magnetic attraction element is configured to magnetically interact with the base of the fixing plate 19 so that, when the pin 18 is inserted at the bottom of the female housing 192, the pin is held in the locking position by means of the magnetic force. Without a position-holding element, it is advisable for the operator to manually hold the gauge during measurement.

[0104] To ensure the repeatability of the measurements, the pin-plate assembly is shaped so that: the ratio between the centering diameter and the centering length is strictly less than 1 (short centering) on ​​the one hand and that the flat support of the plate and the projecting surface of the pin both have a perfectly flat surface (high quality flatness). The presence of means for holding in position, such as the elastic retaining tabs discussed above in relation to figures 2-5 and 10-13, or the magnetic attraction element discussed above in relation to figures 18-19, also makes it possible to improve the reproducibility of the measurements by eliminating the influence of the operator. These are illustrative examples and other implementations are of course possible without departing from the scope of the invention.For example, it is possible to provide for holding the pin-plate assembly in position using means of securing by snap-fastening, % turn, pinning, to name but a few.

[0105] Generally speaking, the geometric tolerance specifications of the pin-plate assembly are based on a centering clearance between the diameter of the plate and the diameter of the pin of between -5 / 100 and +5 / 100 of a millimeter.

[0106] According to a particular aspect of the invention, the positioning pins are made from a metallic material or a rigid and light metallic alloy based on aluminum for example (which can be covered with a reinforcing layer or an anti-wear coating), or from a thermoplastic polymer-based material. As for the fixing plates, they are made from a metallic material or a metallic alloy such as stainless steel for example, or from a polymer-based material (polyamide or PEEK). It will generally be preferred to use materials allowing easy and precise cooperation between the respective male and female parts of the pins and plates.

Claims

Claims

1. Device for measuring the evolution of the distance between at least two points of a structure, the device comprising: - a set of fixing plates (2, 3) each intended to be fixed to one of the points of the structure;- a measuring gauge (1) having a main body (10) from which extend two measuring arms (11, 12) movable relative to each other, the measuring arms each being provided with a positioning pin (13, 14) intended to be secured to one fixing plate of said set of plates, the device being characterized in that the positioning pins are each mounted movable in rotation at one end of one of the measuring arms around at least one axis of rotation so as to make each positioning pin movable in rotation along said at least one axis of rotation relative to the measuring arm associated with it, and in that the positioning pins and the fixing plates are configured to allow reversible securing of the positioning pins in the associated plates.;

2. Device according to claim 1, in which the measuring arms are composed of a movable arm (12) in translation and a fixed arm (11) extending along a measuring axis (X), the positioning pin (14) associated with the movable arm (12) being mounted movable in rotation around at least one axis of rotation (Z2) orthogonal to the measuring axis, and the positioning pin (13) associated with the fixed arm (11) being mounted movable in rotation around a first axis of rotation (Yl) orthogonal to the measuring axis and a second axis of rotation (XI) coaxial with the measuring axis (X).

3. Device according to any one of claims 1 and 2, in which the positioning pins each comprise a male securing portion (132+131-1) provided to cooperate with a female securing housing (21) of the associated fixing plate.

4. Device according to claim 3, in which the female securing housing comprises a plurality of lateral tabs elastically deformable between a locked position and an unlocked position, the unlocked position being taken momentarily during the introduction of the male securing portion into the female securing housing.

5. Device according to claim 4, in which the male securing portion comprises a temporary displacement member and a locking member, and the lateral tabs have in the vicinity of their free end a protrusion forming a projection, the temporary displacement member being shaped to temporarily act on the projections of the lateral tabs to temporarily deform the lateral tabs during the introduction of the male securing portion into the female securing housing.

6. Device according to any one of claims 1 to 5, in which the fixing plates are each provided with a plurality of lateral grooves.

7. Device according to any one of claims 1 to 6, in which the fixing plates have a base (25) in which a central through hole is provided intended to receive an element for fixing to the structure, a plurality of through openings distributed around the periphery of said base and a plurality of contact pins distributed on a contact face of said base.

8. Fixing plate intended to be part of a set of fixing plates included in a measuring device defined according to any one of claims 1 to 7.

9. Method for measuring the evolution of the distance between at least two points of a structure by means of a measuring gauge (1), the measuring gauge (1) being provided with two measuring arms (11, 12) movable relative to each other and positioning pins (13, 14) each mounted movable in rotation at one end of one of the measuring arms (110, 120) around at least one axis of rotation, the method being characterized in that it comprises the following steps: - positioning the measuring gauge by securing the positioning pins in a first pair of fixing plates (151-152) of a set of fixing plates previously fixed on the structure, a first plate being fixed on a first point of the structure and a second plate being fixed on a second point of the structure; - measuring the distance between said first and second points of the structure.

10. The method of claim 9, wherein the step of placing the measuring gauge is further performed for a second pair of fixing plates (151-153) of said set previously fixed on the structure, the second pair comprising a third plate of fixing fixed on a third point of the structure and said first fixing plate, the measuring step is further carried out to measure the distance between said first and third points of the structure and the distance between said second and third points of the structure.

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