Patent Application
20220404806
This application claims the benefit of the French patent application No. 2106404 filed on Jun. 17, 2021, the entire disclosures of which are incorporated herein by way of reference.
The present invention relates to a method for assisting with the positioning of a drill bit for boring a component and potentially a plurality of components for the assembly thereof
In industry, in particular in the aeronautical industry, it is often necessary to create bores in a component. To this end, it is known to position the component on a machine tool bearing a drill bit, and to program the machine tool such that the drill bit and/or the plate is/are moved so as to align the drill bit with the position at which the bore needs to be created.
In spite of all the care taken during the positioning of the components, the positioning of the bore may be slightly different from what is expected. Such a difference may be due, for example, to the tolerances of the machine tool, a slight discrepancy in the positioning of the component, etc.
In other words, the position of each bore is determined with respect to the reference frame of the machine tool, and incorrect positioning of the component or the tolerances of the machine tool have an impact on the position of the bores.
In particular, when a component has a large size, a slight discrepancy in the positioning of the component or in the movement of the drill bit may have significant consequences on account of the great length of the component.
Moreover, when it is necessary to fix two components together, the above method is carried out for each component and the discrepancies are copied over to each component and add up, making assembly difficult.
It is an object of the present invention to propose a method for assisting with the positioning of a drill bit for boring a component, and potentially a plurality of components for the purpose of assembling them.
To this end, there is a proposed a method for assisting with the positioning of a drill bit for boring a component, carried out with the aid of a machine tool having a control unit, a drill head bearing the drill bit and at least one optical sensor secured to the drill head, wherein the method involves:
for a first component,
With such a method, the component is drilled precisely on the basis of a triangulation with respect to notable points on the components and not with respect to the machine tool.
Advantageously, before the first capturing step, the method involves a uniqueness step, during which the face of the first component to be drilled is rendered unique by putting notable points on the face.
Advantageously, there is at least one additional component, and the method involves:
and, for each additional component,
Advantageously, before the third capturing step, the method involves a uniqueness step, during which the face of each additional component to be drilled is rendered unique by putting notable points on the face.
The features of the invention that are mentioned above, and others, will become more clearly apparent from reading the following description of an exemplary embodiment, the description being given in relation to the appended drawings, in which:
Although the following description is oriented more particularly toward the case of an assembly of several components 102a-c, the method according to the invention that is described below may be used first and foremost in the case of the drilling of a single component 102a and optionally in the case of the drilling of several components 102a-c for the purpose of assembling them.
The general principle of the invention comprises using at least one optical sensor, for example a camera, in order to capture at least one image of the or each component including the face to be drilled, to construct a digital representation of the or each component, to identify the notable points thereon, and, on the basis of these notable points, the machine tool calculates the appropriate position at which the machine tool needs to position the drill bit. The aim is to create bores 106a-b, for example for the fitting of the bolts 104a-b, on the basis of a reference frame associated with the component 102a-c and not on the basis of a reference frame associated with the machine tool.
As the case may be, it may be sufficient to have a digital representation of the entire component or only of the surface to be drilled, for example when the component is only a flat panel. Thus, as the case may be, the use of a single optical sensor capturing a single image may be sufficient, in combination with a method for contour detection for example in order to obtain a two-dimensional digital representation of the surface to be drilled. However, it may be necessary to use several optical sensors, each capturing at least one image, and then to use a method for example of the stereo-correlation type in order to obtain a three-dimensional (3D) digital representation of the component.
The machine tool has a drill head bearing a drill bit and movement means which make it possible to move the drill head in the entire space covered by the machine tool. Each movement means is for example a motor-driven slide system. The machine tool also has a motor driving the drill bit in rotation.
The machine tool also has at least one optical sensor secured to the drill head in order to obtain a two-dimensional digital representation of the component or at least two optical sensors in order to obtain a two-dimensional digital representation of the component.
The machine tool also has a control unit which controls each movement means, the or each optical sensor and the drill bit motor, and a schematic depiction of which is shown in
The control unit 300 has, connected by a communication bus 302: a processor 304 or CPU (“Central Processing Unit”); a RAM 306 (“Random Access Memory”); a ROM 308 (“Read Only Memory”); a storage unit 310 such as a hard disk or a storage medium reader, such as an SD (“Secure Digital”) card reader; at least one communication interface 312, allowing, for example, the processing unit to communicate with the movement means, the or each optical sensor, the motor driving the drill bit in rotation, etc.
The processor is capable of executing instructions loaded into the RAM from the ROM, from an external memory (not shown), from a storage medium (such as an SD card), or from a communication network. When the machine tool is powered up, the processor is capable of reading instructions from the RAM and of executing them. These instructions form a computer program causing the processor to implement all or part of the algorithms and steps that are described below.
All or part of the algorithms and steps that are described below may be implemented in the form of software by the execution of a set of instructions by a programmable machine, for example a DSP (“Digital Signal Processor”) or a microprocessor, or may be implemented in the form of hardware by a machine or a dedicated component, for example an FPGA (“Field-Programmable Gate Array”) or an ASIC (“Application-Specific Integrated Circuit”).
With the aid of the or each optical sensor, at least one image of the first component 102a to be drilled including the face to be drilled on which notable points 202 are identified is captured and then saved in the storage unit 310. The presence of these notable points 202 which vary from one component 102a-c to another allows unique identification of each component 102a-c. The notable points 202 are identified for example by the control unit 300 through a difference in contrast between the notable points 202 and the first component 102a with the aid of appropriate image processing software.
On the basis of the or each image thus captured, the control unit 300 will calculate a digital representation of the first component 102a. This digital representation may be a two-dimensional digital representation or, as already explained, the capture of two images by different optical sensors makes it possible to use a stereo-correlation method to obtain a 3D digital representation of the first component 102a.
On the basis of the design data of the first component 102a that are received, for example from CAO software, and constitute a digital design representation, the control unit 300 digitally superposes the digital representation of the first component 102a calculated beforehand and the digital design representation of the first component 102a, including the centers of the bores 106a-b to be created.
Following superposition of the two digital representations, it is then possible to evaluate the position of each center of a bore 106a-b with respect to several of the notable points 202, thereby effecting a transfer of the centers of bores to the digital representation calculated.
On the basis of this superposition, the distances of the center of each bore 106a-b from a plurality of notable points 202 on the face of the first component 102a are evaluated by the control unit 300. The position of the center of each bore 106a-b is thus determined by triangulation with respect to the different notable points 202 on the face of the first component 102a. While the triangulation can be effected on the basis of two notable points 202, the greater the number of notable points 202, the greater the precision, and preference will be given to using as a basis an image in which the center of the bore 106a-b to be drilled is at the center of a plurality of notable points 202.
Each notable point 202 is conflated with its barycenter or is divided into a number of pixels and each pixel becomes a notable point 202.
On the basis of this determination of the position of the center of each bore 106a-b with respect to the notable points 202 and by analysis of the image of the face of the first component 102a captured live by the or each optical sensor, the control unit 300 then orders the drill head to move, by actions on the movement means, so as to position the drill bit vertically in line with the center of each bore 106a-b to be created. By virtue of each image received live by the control unit 300 during the movement of the drill head, the control unit 300 detects the notable points 202 used for the triangulation, and determines the position of the center from these different notable points 202 on the face of the first component 102a and the previously calculated distances. Each bore 106a-b is then created in the first component 102a.
The identification of the position to be reached comprises, for example, finding the image of the notable points 202 surrounding the center of the bore to be drilled in the first component 102a, for example using the Haar cascade method.
The position of the center of the bore 106a-b is therefore evaluated on the basis of the physical data of the first component 102a and no longer on the basis of the intrinsic data of the machine tool, giving rise to greater precision.
When it is envisaged to assembly several components together, it is desirable to align the bores of the different components 102a-c to allow easy assembly.
Once the bores 106a-b have been created in the first component 102a, a new image of the first component 102a including the face drilled with the bores 106a-b is captured by the or each optical sensor and saved in the storage unit 310. Then, the control unit calculates a new digital representation of the first component 102a from the or each image thus captured.
For a second component 102b, a similar process is carried out with, in the same way, notable points 202 arranged on the face of the second component 102b that needs to be drilled. At least one image of the additional component 102b including this face to be drilled is captured by the or each optical sensor and saved in the storage unit 310. As in the case of the first component 102a, a digital representation of the additional component 102b is calculated from the or each image thus captured.
The digital representation of the drilled first component 102a and the digital representation of the additional component 102b are then superposed in the position that the two components 102a-b need to take up in the assembly 100, making it possible to place the bores in the first component 102a on the image of the face of the second component 102b and thus to align the different bores 106a-b for the purpose of assembly.
On the basis of this superposition and in a similar way to before, the distance of the center of each bore 106a-b in the second component 102b with respect to each notable point 202 on the face of the second component 102b is evaluated by the control unit 300.
As before, with the aid of the or each optical sensor, the control unit 300 determines the position of the center of each bore 106a-b to be created in the second component 102b from the different notable points 202 on the second component 102b that arise from the images captured live. Then, each bore 106a-b is created in the second component 102b.
The same process is repeated for each complementary component 102c to be assembled.
Such a process is therefore relatively simple to implement and the use of a plurality of points for the triangulation and positioning of the drill head makes it possible to achieve a high level of precision.
Moreover, all the data thus collected about the different components are stored and can be retrieved if necessary, for example in the case of maintenance or replacement of a component.
for the first component 102a,
When there is at least one additional component 102b-c, the method also involves:
for the first component 102a, after the first positioning step 412,
and, for each additional component 102b-c,
From the second positioning step 426, the process loops to the third capturing step 418 for each additional component 102b-c.
As explained above, the notable points 202 may be features of the component 102a-c or points added to the face of the component 102a-c either by the deposition of points of paint or by the placement of a printed sheet.
When there is a single component 102a to be drilled, the method then involves, before the first capturing step 404, a uniqueness step 402, during which the face of the first component 102a to be drilled which is seen by the or each optical sensor is rendered unique by putting notable points 202 on the face.
In the case of an assembly 100, the method then involves, before the third capturing step 418, a uniqueness step 402, during which the face of each additional component 102b-c to be drilled which is seen by the or each optical sensor is rendered unique by putting notable points 202 on the face.
In the embodiment of the invention presented in
While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2106404 | Jun 2021 | FR | national |
