Device for the contactless three-dimensional inspection of a mechanical component with toothing

Abstract

A device is proposed for the contactless three-dimensional inspection of a circular, mechanical component (20) with toothing having a main axis of rotation, comprising: means for scanning the teeth, comprising at least one first pair of laser measurement modules (12A, 12B) and means for the rotational driving (11), about the main axis, of said component relative to the laser measurement modules; means for rebuilding a virtual three-dimensional representation of the component using data coming from said scanning means; means of dimensional inspection using the three-dimensional representation; each pair of modules comprising a first module oriented towards a first face of a tooth and a second module oriented towards a second face of a tooth; the modules being oriented relative to the component so that during a rotation of the component, the scanning means scan the first and second faces of each tooth throughout their thickness and depth.

Claims

1. A method of contactless three-dimensional inspection of a circular mechanical component with toothing having a main axis of rotation, teeth of said toothing having a defined thickness and a defined depth, each tooth having a first face and a second face, the method comprising: engendering rotation, about the main axis, of said circular mechanical component relative to laser measurement modules, or vice versa, in which the laser measurement modules include a first module oriented towards the first face of a tooth and a second module oriented towards the second face of a tooth; scanning each of said teeth with the laser measurement modules while a rotational drive engenders the rotation, the laser measurement modules being oriented relative to said circular mechanical components so that during the rotation of said laser measurement modules or of said circular mechanical component about the main axis, said scanning entails a scan of said first and second faces of each tooth throughout their thickness and depth; building a virtual three-dimensional representation of said circular mechanical component using data coming from said scanning; and performing dimensional inspection using said virtual three-dimensional representation.

2. The method of claim 1, wherein each laser measurement module comprises a source of emission of a laser beam oriented relative to the main axis of rotation and relative to a radial axis of said circular mechanical component, and a laser beam receiver oriented to pick up the laser beam coming from said circular mechanical component.

3. The method of claim 2, wherein the laser beam is oriented relative to the main axis of rotation by a first angle ranging from 10 to 45 degrees and relative to the radial axis by a second angle ranging from 10 to 45 degrees.

4. The method of claim 1, further comprising driving the circular mechanical component in translation along the main axis relative to the laser measurement modules, or vice versa.

5. The method of claim 4, wherein said circular mechanical component with toothing includes a shaft with toothing disposed along the main axis and comprising a plurality of toothings placed one after the other along the main axis of rotation.

6. The method of claim 1, wherein the first and second module comprise a first pair of laser measurement modules, and wherein the laser measurement modules comprise a second pair of laser measurement modules, each module of the first and second pairs being placed at the level of each toothing of said plurality to enable a scanning of said first and second faces of each tooth throughout their thickness and depth and for each toothing.

7. The method of claim 6, further comprising driving the circular mechanical component in translation along the main axis relative to the laser measurement modules, or vice versa, and further comprising a third pair of laser measurement modules oriented relative to said circular component so that, during the rotation of said modules or said circular mechanical component about the main axis and during the translation of said modules or of said circular mechanical component relative to the main axis, said scanning furthermore entails a scan of said shaft throughout its rim and its height.

8. The method of claim 1, wherein said circular mechanical component with toothing is a toothed wheel comprising a circular hole having the main axis of rotation of said circular mechanical component as its axis and further comprising an additional laser measurement module oriented relative to said circular mechanical component so that, during the rotation of said modules or of said circular mechanical component about the main axis, said scanning entails a scan of the circular hole throughout its surface.

9. The method of claim 1, wherein the circular mechanical component with toothing belongs to a group comprising one or more of a component with straight toothing, a component with helical toothing, and a component with herringbone toothing.

10. The method of claim 1, wherein the laser measurement modules include a line-type laser emitting source.

Description

5. BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) Other features and advantages of the disclosure shall appear from the following description given by way of an indicatory and non-exhaustive example and from the appended drawings of which:

(2) FIG. 1 is a view in perspective or three-quarter view of a set of measurement modules of a three-dimensional inspection device, according to one particular embodiment of the disclosure, performing a scan of the surface of a toothed wheel;

(3) FIGS. 2A-2F are schematic views showing different phases of the process of laser scanning of the toothed wheel illustrated in the context of the embodiment of FIG. 1;

(4) FIG. 3 presents the schematic structure of a three-dimensional inspection device in the form of schematic blocks according to one particular embodiment of the disclosure;

(5) FIG. 3A illustrates an example structure of the inspection device for a particular embodiment;

(6) FIG. 4 is a view in perspective or three-quarter view of a three-dimensional inspection device performing a scan of the surface of a shaft with multiple toothings according to one particular embodiment of the disclosure;

(7) FIGS. 5A-5C represent partial and detailed views of the inspection device illustrated in FIG. 4;

(8) FIG. 6 is a drawing illustrating a particular orientation of a laser beam for a measurement module scanning a tooth face.

6. DETAILED DESCRIPTION OF EMBODIMENTS

(9) In all the figures of the present document, the identical elements and steps are designated by one and the same numerical reference.

(10) Referring to FIGS. 1, 2A to 2D, we describe the structure and working of a contactless three-dimensional inspection device 10 according to one particular embodiment of the disclosure, adapted to the inspection of circular mechanical components with toothing taking the form of a toothed wheel (or pinion gear) 20.

(11) The inspection device 10 comprises, in the embodiment illustrated in FIG. 1, an object-holder 11 mounted rotationally mobile relative to a frame (not illustrated in the figure). The object-holder 11 holds the toothed wheel 20 to be inspected within the device. The object-holder 11 cooperates with the system used to drive the object-holder in rotation, the unit forming means for the rotational driving of the toothed wheel according to the disclosure.

(12) In general, a toothed wheel 20 has a main rotation axis Z and a radial axis X orthogonal to the axis Z. Each tooth of the toothed wheel 20 has a given thickness e along the main axis (corresponding to the segment AB) and a given depth p along the radial axis (corresponding to the segment AC). Each tooth also has two main faces F.sub.A and F.sub.B. In this example, the thickness of the toothed wheel 20 is 2.5 cm and its depth is 1 cm for example.

(13) The toothed wheel 20 is an annular component provided with an external toothing and a through hole passing along its main axis. This hole has an internal wall that is smooth or tapped for example.

(14) In FIG. 1, the inspection device 10 according to the disclosure implements four laser measurement modules dedicated to the inspection of the toothing of the toothed wheel 20, namely: a first pair of laser measurement modules 12A-12B dedicated to a first surface measurement of the teeth of the toothed wheel 20 and a second pair of laser measurement module 13A-13B dedicated to a second surface measurement of the teeth of the toothed wheel 20. More particularly, each pair of laser measurement modules (12A-12B; 13A-13B) is constituted by first module (12A; 13A) oriented towards a first face of a tooth of the toothing and a second module oriented towards the second face of a second tooth of the toothing. Thus, the first modules 12A and 13A are disposed appreciably upwards relative to the toothed wheel 20 and the second modules 12B and 13B are disposed appreciably downwards relative to this toothed wheel 20.

(15) For a given pair of measurement modules, the two measurement modules of a given pair are disposed so as to measure a same tooth of the toothing or two distinct teeth of the toothing as is the case in FIG. 1. Each laser measurement module of the two pairs of modules represented here is fixedly attached to a frame by means of a support (not shown) that can be configured or modulated according to the component to be inspected and its dimensional characteristics. This enables the orientation of each measurement module appropriately according to the face of the teeth with which it is associated and the dimensions of the toothed wheel 20.

(16) In the example illustrated herein, the laser measurement modules, 12A, 12B, 13A and 13B are fixed and it is the object-holder 11 that is mobile in rotation about the main axis Z of the toothed wheel 20. Naturally, an alternative embodiment can be envisaged in which the object-holder 11 is fixed and it is the frame to which the modules are fixedly attached that is mobile in rotation about the main axis Z of the toothed wheel 20.

(17) The set of laser measurement modules illustrated herein constitutes the laser scanning means of the device according to the disclosure. The laser scanning means are associated with means for processing measurements acquired by the scanning means (the principle of which is described further below with reference to FIG. 3) to rebuild the three-dimensional surface of the toothed wheel and carry out a dimensional inspection of this toothed wheel.

(18) According to the disclosure, the laser measurement modules 12A, 12B, 13A and 13B are oriented relative to the toothed wheel 20 so that during a rotation of the toothed wheel 20 about its main axis Z, the scanning means scan the first and second main faces F.sub.A and F.sub.B of each tooth of the toothed wheel throughout their thickness e and depth p.

(19) The FIGS. 2A to 2F represent different phases of the laser scanning process for scanning the toothed wheel 20 for a given laser measurement module, such as the module 12B for example. Only the laser beam emitted by the measurement module is illustrated here, for reasons of readability of the drawings.

(20) The measurement module 12B is, in this example, a laser measurement module working according to the principle of laser triangulation. In a known way, such a measurement module is capable of measuring a distance by angular computation. It also covers a wide range of measurements and has high resolution. Known technologies other than laser triangulation can of course be used without departing from the framework of the disclosure. The measurement module 12B comprises a laser emission source 121, for example a laser diode that projects a plane laser beam 16 on one of the faces of the teeth to be scanned (here the main face F.sub.B) and a laser receiver 122, for example a CCD (Charge-Coupled Device) type sensor or CMOS (Complementarity Metal-Oxide-Semiconductor) type sensor. The laser emission source and the corresponding laser receiver are situated on the same face of the measurement module, this face being oriented towards the toothed wheel 20.

(21) The other measurement modules 12A, 13A and 13B are preferably identical. In general, to maximize the laser scanning quality, the measuring modules of each pair must be of identical technology.

(22) When the object-holder 11 (and therefore the toothed wheel 20) is put into rotation, the laser beam emitted by the source is reflected on the face F.sub.B of the toothed wheel 20, for which it is desired to know the position or distance from the laser source (i.e. relative to the measurement module 12B). The laser receiver 122 is oriented to pick up the laser beam coming from the toothed wheel 20. The reflected laser beam reaches the receiver 122 at an angle that depends on the distance. The position of the laser beam reflected on the receiver 122 as well as the distance between the source and the receiver of the measurement module 12B can be used to deduce the information on distance for each measurement point acquired.

(23) The intersection between the laser beam 16 and the face F.sub.B of the tooth forms a scanning laser line 18 that moves on the scanned face F.sub.B as and when the toothed wheel 20 rotates about its main axis, as illustrated in FIGS. 2A to 2F.

(24) More particularly, according to the disclosure, the measurement module 12B is laid out so that the emission source 121 is oriented relative to the main axis of rotation Z on the one hand and relative to a radial axis X of the toothed wheel 20 on the other hand so that the laser line 18 covers the entire depth of the toothed system p (i.e. from head to foot of each tooth) and so that the laser line 18 scans the entire thickness e of the of the toothing as and when the toothed wheel 20 rotates.

(25) In other words, the measurement module 12B is laid out relative to the toothed wheel 20 so that the laser line 18 cover the entire depth of the teeth, the scanning of the teeth on their thickness being obtained through the rotation of the toothed wheel 20.

(26) One of the conditions relating to the orientation of the modules is that the axis of orientation of the laser beam of the modules can be inclined relative to the radial axis and the main rotation axis but should not be orthogonal with the main rotation axis.

(27) FIG. 6 illustrates a particular example of orientation of the laser beam of the measurement module 12B relative to the face of one of the teeth being scanned. P denotes the plane containing main axis Z and the radial axis X. The measurement module 12B is oriented towards the second face F.sub.B so that the laser beam is inclined upwards relative to the radial axis X by an angle θx ranging from 10 to 45 degrees (for example 30 degrees) and by an angle θz relative to the main rotation axis Z ranging from 10 to 45 degrees (for example 20 degrees). The angles θx and θz depend especially on the angle of inclination α of the teeth of the toothing (or helix angle). The angle of inclination α usually varies from 15 to 30 degrees, for example, for pinion-gear type parts.

(28) The same principle can be applied to the first module 12A of the pair of measurement modules 12A and 12B, the laser beam of said module 12A having to be inclined downwards relative to the radial axis X of the angle θx to face the corresponding tooth face F.sub.A.

(29) Finally, to carry out a scan of the toothed wheel 20 in its totality (and not only at the level of the toothing system of the component), the scanning means comprise a fifth laser measurement module 14 distinct from the two pairs of modules 12A-12B and 13A-13B, placed appreciably upwards relative to the toothed wheel 20 so as to enable a laser scan at the upper surface of the toothed wheel 20 and more specifically at the through hole. The measurements derived from this measurement module 14 make it possible to measure the main rotation axis of the toothed wheel 20 and to inspect the dimensions of the through hole. The working of the measurement module 14 is identical to the one described further above for the other measurement modules.

(30) It must be noted that, should the toothed wheel to be inspected has a toothing with a thickness such that the size of the laser beam of the scanning means enable only a partial scanning of the thickness of the toothing during rotation, it can be planned that the scanning means are furthermore provided with means for the driving in translation of the toothed wheel 20 along the main axis Z relative to the laser measurement modules (or vice versa) to carry out a full scan of the entire thickness of the toothing. It is therefore possible making provision for a simultaneous or sequenced motion in rotation and translation motion of the component relative to the laser measurement modules (or vice versa).

(31) The number of pairs of the measurement modules is not limited to the example illustrated here above. A greater number (i.e. a number greater than 2) or a smaller number (i.e. a number smaller than 2) could be envisaged without departing from the framework of the disclosure, especially depending on the complexity of the shape of the mechanical component, the number of measurement points desired and/or the processing time desired and/or other parameters that those skilled in the art will deem it appropriate to take into account.

(32) FIG. 3 now presents the generic characteristics of the three-dimensional inspection device 100 in the form of functional blocks, according to one particular embodiment of the disclosure.

(33) The inspection device 100 comprises scanning means 110 for scanning each of the teeth of the toothing of the component to be inspected. These scanning means are provided with laser measurement modules and driving means as described further above with reference to FIGS. 1, 2A to 2F.

(34) The inspection device 100 comprises means 120 for building a virtual three-dimensional representation of the component using data (or measuring points) derived from the scanning means 110. To this end, the inspection device 100 implements a software program for processing clouds of points and for the virtual three-dimensional representation of the component to be inspected. The data coming from the modules take the form of clouds of points of co-ordinates defined in a three-dimensional space. The time needed to read the points is relatively short (between 1 to 30 million points, depending on the number of measurement modules, are acquired in a time span of one second to five seconds). In general, a single 360-degree rotation of the component (at the altitude where the component needs to be measured) is enough to acquire all the measuring points needed for the three-dimensional rebuilding and the dimensional inspection of the component.

(35) The inspection device 100 comprises means of dimensional inspection of the component according to the virtual three-dimensional representation obtained by the building means 120. The inspection means 130 are configured to deliver 140 at least one quantity representing a dimension of the mechanical component or a piece of information accepting or rejecting the component subjected to inspection according to the result of the inspection made by the inspection means 130 (compliance or non-compliance with dictated dimensional and/or geometrical tolerance values, etc.).

(36) Such an inspection device can easily be integrated into a production line.

(37) FIG. 3A illustrates an exemplary structure of the inspection device 100 for a particular embodiment. The inspection device 100 includes at least one non-transitory computer-readable medium 150 and a processor unit 160, e.g. having a microprocessor μP, which is controlled by code instructions of a computer program 170, which is stored on medium 150. When executed by the processing unit 160, the code instructions configure the inspection device 100 to perform and control a contactless three-dimensional inspection as described herein, such as the functional blocks shown in FIG. 3.

(38) Referring now to FIGS. 4, 5A to 5C, we present the structure and working of a contactless three-dimensional inspection device 1 adapted to inspecting circular mechanical parts with toothing systems taking the form of a shaft 5 with multiple toothing.

(39) The inspection device 1 comprises two vertical arms 6A and 6B in the form of tips holding the shaft 5 with toothing at each of its extremities along its main rotation axis. The arm 6B cooperates with a dual rotation and translation drive system enabling the shaft 5 with toothing to be put into rotation and/or translation relative to the frame 7 that is fixed to it. The arm 6A cooperates with a simple system for driving in translation (guidance in translation of the shaft along its main axis). These elements form the means for driving the device according to the disclosure in rotation and in translation.

(40) The shaft 5 with toothing herein has three toothings 50, 51 and 52 placed at different levels of the shaft along the main rotation axis Z. The radial axis of the toothing 50, for example is denoted X, and is orthogonal to Z. Each toothing system can be of a different type (helical toothing, straight toothing, herringbone toothing etc.) and can have different dimensions.

(41) Here below in the description, we shall strive initially to describe the device for carrying out an inspection of the helical toothing 50 of the shaft 5.

(42) The inspection device 1 according to the disclosure implements four laser measurement modules to inspect the toothing 50 of the shaft 5, namely: a first pair of laser measurement modules 2A-2B dedicated to a first measurement of the surface of the teeth of the toothing 50 and a second pair of laser measurement modules 3A-3B dedicated to a second surface measurement of the teeth of the toothing 50. More particularly, each pair of laser measurement modules (2A-2B; 3A-3B) is constituted by a first module (2A; 3A) oriented towards a first face F.sub.A of a tooth of the toothing and a second module oriented towards the second face of another tooth of the toothing, according to the same principle as the one developed further above with reference to the toothed wheel (FIG. 1, 2A to 2F). Thus, according to the disclosure, the laser measurement modules 2A, 2B, 3A and 3B are oriented relative to the toothing 50 so that, during a rotation of the shaft 5 about its main axis Z, the scanning means carry out a scanning of the first and second main faces F.sub.A and F.sub.B of each tooth of the toothing 50 throughout its thickness and depth.

(43) In addition to the rotational driving means, means for driving the shaft 5 with toothing in translation are provided in the inspection device 1, to enable the guidance of the shaft along its main axis Z during or not during the rotation of the shaft 5 with toothing (a motion of the shaft in translation can be implemented simultaneously or not simultaneously with a motion in rotation). This makes it possible firstly to carry out a full scan throughout the thickness of a toothing when this toothing has a thickness such that the size of the laser beam of the measurement modules does not enable the entire thickness of the toothing to be covered. Secondly, the translational driving means can be activated to shift the component along the main axis to enable a scanning and an acquisition of the points of measurement of the other toothings 51 and 52 of the shaft (this has the effect of enabling a scanning of the first and second main faces of each tooth throughout its thickness and depth, and to achieve this for each toothing) and, as the case may be, the other parts of the component in order to carry out a complete inspection of the shaft 5 with toothing. It must be noted that to carry out a sequenced scanning of the toothings 50, 51 and 52 using the same pairs of measurement modules, the type of profile and the dimensions must be appreciably similar. This depends on the field of measurement of the measurement modules used in the inspection device (the field of measurement that can effectively vary by a few millimeters to a few centimeters depending on the technology of the measurement modules). As the case may be, the orientation of the laser measurement modules 2A, 2B, 3A, 3B should be adapted to the type of toothing with which the component is provided. A mechanical system of automatic orientation of the modules could be envisaged to adapt in real time to the shape and dimensions of the mechanical component to be inspected.

(44) This configuration enables a sequenced scanning of the different parts of the shaft 5 including all the toothings.

(45) As an alternative to this configuration, the scanning means can include at least one other pair of laser measurement modules (not illustrated in the figures) placed at the level of each toothing of the shaft to enable a scanning and an acquisition of the measurement points of the faces of each tooth of each toothing throughout their thickness and depth (the orientation of the modules is configurable in real time).

(46) This configuration enables a simultaneous scanning of all the toothings placed at different levels along the main axis of the shaft 6 with toothing thus reducing the time of inspection of the component.

(47) Thus, the device according to the disclosure enables an automatic, complete and contactless inspection of the component capable of having a complex shape, especially with several levels of toothings, themselves having different profiles of teeth, different sizes (depth, thickness, diameter etc.).

(48) In addition, the scanning means can be configured to scan not only the toothings but also the surface of the remaining parts of the shaft 5 in order to make it possible to determine the position of the main axis of rotation of the component. In one alternative embodiment, this scanning operation is carried out by the additional measurement modules 4A, 4B, 4C, 4D disposed so as to be fixed relative to the frame 7 and perpendicular to the axis of the component. The surface of said remaining parts of the shaft 5 is checked by activating the means of rotational driving and the means of translational driving of the shaft 5 relative to the measurement modules so as to scan the surface of said remaining parts throughout their rim and throughout their height respectively.

(49) An exemplary embodiment of the present disclosure overcomes the various drawbacks of these prior art techniques of dimensional measurement and inspection.

(50) More specifically, an exemplary embodiment provides an inspection device that enables, contactless, high-speed, complete, automatic, three-dimensional inspection of a mechanical component with toothing.

(51) Although the present disclosure has been described with reference to one or more examples, skilled persons will recognize that changes may be made in form and detail without departing from the scope of the disclosure and/or the appended claims.