PART HOLDING TOOLS

Abstract

TOOL FOR HOLDING A PART The invention relates to Tool (1) for holding a part (2) comprising: a lower plate (10), an upper plate (11) parallel to the lower plate (10) and movable in translation, characterized in that each of the upper (10) and lower (11) plates comprises a block of foam (30, 31), the foam having a density of less than 300 kg / m3. This allows isostatic support on all points of contact of the part, which improves the extraction of the iso-surface of the part during analysis. The foam must be sufficiently rigid to avoid crumbling which would cause the initial support of the part to be lost. This density guarantees the geometry of the foam for use of at least 100 assemblies and disassemblies of the part without crumbling. Figure to be published with the abstract: Figure 1

Description

Title of the invention: TOOL FOR HOLDING A PART TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is the field of non-destructive testing, and specifically by X-ray tomography.

[0002] More particularly, it relates to a part holding tool which is versatile for controlling material health and dimensions from tomographic data produced in several independent acquisitions. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Contact control with a Coordinate Measuring Machine (CMM) or optically allows precise dimensional measurements to be made but has the following disadvantages: • No access to internal areas of parts with complex geometry, • No capacity to carry out a material health check.

[0004] There is also tomography control, which consists of reconstructing the volume of an object from a series of measurements taken from outside the object. However, for large parts, it is necessary to carry out several independent acquisitions in order to control the entire part. The registration of acquisitions is not controlled for dimensional control without dedicated tooling and registration protocol. These measurements are therefore particularly problematic for aeronautical parts such as upper diaphragm tubes (UDT: Upper Diaphragm Tube).

[0005] In the context of X-ray tomography control of a composite part, there is a need to be able to carry out a double control, of material health and dimensions, from a tomographic reconstruction based on several acquisition sets. But without dedicated tooling, dimensional control cannot be carried out according to the rules of the art, in particular with regard to the accuracy of the registration. Summary of the invention

[0006] The invention offers a solution to the problems mentioned above, by providing a reliable solution to guarantee a recalibration between the acquisitions allowing the reconstruction of a tomographic volume with sufficient precision for dimensional control, while guaranteeing accessibility for material health control.

[0007] The tool for holding a part according to the invention comprises: • a lower tray, • an upper plate parallel to the lower plate and movable in translation, • it is characterized in that each of the lower and upper plates comprises a block of foam, the foam having a density of less than 300 kg / m3. This allows isostatic support at all contact points of the part, which improves the extraction of the iso-surface of the part during analysis. The foam must be sufficiently rigid to avoid crumbling which would cause the initial support of the part to be lost. This density guarantees the geometry of the foam for use of at least 100 assemblies and disassemblies of the part without crumbling.

[0008] Advantageously, the tooling comprises at least three balls with a density of less than 3g / m3, preferably less than 2.8g / m3, arranged in a plane parallel to the two plates. The low-density calibrated balls are preferably aligned with the overlapping areas of the acquisition scans and without any contact point with the part. For three balls, the spacing is at least 90° between two balls to ensure correct registration on each overlapping area. For a number greater than three, the balls will be spaced at least 45° apart, which makes it possible to insert eight balls without loss of quality on the registration.

[0009] Advantageously, the balls have a diameter of 6mm ±0.2mm. These balls are used for calibration and can be made of aluminum, but balls made of ceramic or other denser material are prohibited. They are of standard size and therefore easy to find on the market.

[0010] Advantageously, the balls are held in a holding element connected to tubes, preferably hollow. This makes it possible to reduce the impact of artifacts on the part. These holding elements are, for example, foam blocks, “transparent” to X-rays.

[0011] Advantageously, the tubes are hollow and have a wall thickness of less than 3 mm, preferably less than 2 mm.

[0012] Advantageously, the tubes have a density of less than 2g / m3. Preferably the tubes are made of carbon.

[0013] Advantageously, the balls are fixed to the hollow tubes by a holding element with a density of less than 300 kg / m3. This element may be foam.

[0014] Advantageously, the holding elements are adjustable in height on the tubes. It is thus possible to position each ball at a desired height. Each holding element, for example foam blocks, is provided with a screw, preferably a butterfly screw at the rear allowing the assembly to be tightened and loosened and moved on the tube.

[0015] Advantageously, the foam block of the lower plate has a bearing surface inclined relative to the lower plate. This makes it possible to reduce edge effects and improve the extraction of the iso-surface.

[0016] Advantageously, the support surface is inclined by 5 to 10° relative to the plate.

[0017] Advantageously, the trays are rotating. BRIEF DESCRIPTION OF THE FIGURES

[0018] The figures are presented for information purposes only and in no way limit the invention.

[0019] [Fig. 1] is a section of a holding tool according to the invention,

[0020] [Fig.2] is a section of the bottom of the tool,

[0021] [Fig.3] shows a detail of the positioning of the part on the foam

[0022] [Fig.4] is a view along a section IV-IV,

[0023] [Fig.5] is a perspective view of the tooling according to the invention. DETAILED DESCRIPTION

[0024] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0025] Throughout the description, the upper part of the figures will be called “top” or “upper” and the lower part of said figures will be called “bottom” or “lower”.

[0026] In [Fig.l], we can see the tool 1 with a part 2 to be measured, here an upper membrane tube (UDT).

[0027] The tool 1 comprises a lower plate 10 and an upper plate 11 parallel to each other and connected to each other by several tubes 12 (here three), preferably made of carbon. The upper plate 11 is movable in translation on the tube 12. The tool 1 is rotatable around an axis X located at the center of the plates 10 and 11 in order to be able to establish the measurements over the entire surface of the part 2.

[0028] The lower plate 10 is secured to a lower foam block 30 and the upper plate 11 to a foam block 31. The two foam blocks 30 and 31 are arranged opposite each other. The foam blocks 30 and 31 are low density, i.e. less than 300 kg / m3. These foam blocks have a height h of approximately 130 mm.

[0029] The tubes 12 each comprise at least one holding element 13 connected to a ball 14 which can for example be inserted at the end of the holding element 13. These holding elements 13 with their respective balls 14 form a series where these elements converge and are coplanar, it can be made of a block of foam which is held on the tube 12 which is part of the structure of the holding tool 1 and they are adjustable in height by means of screws 4 (see [Fig.5]). In the example illustrated in [Fig.l], there are two series of holding elements 13. The series of holding elements 13 with their balls 14 are distributed uniformly over the height of the tubes 12. In the example illustrated, the series of holding elements 13 are placed at a distance di of 220mm and d2 430mm from the lower plate 10 for a part 2 with a height of 650mm, but these spacings are adjustable from 50mm to 600mm. It is possible to changing the holding elements 13 to change the spacing between the balls 14, by choosing holding elements 13 that are longer or shorter.

[0030] These balls 14 are used for calibrating the part 2. The distance between the tube and the end of the ball 14 is approximately 50mm.

[0031] The holding elements 13 are preferably of the foam type with a density of less than 300 kg / m3. The balls 14 preferably have a density of less than 3 g / cm3 or even 2.8 g / m3, they may be made of carbon. Their diameter is approximately 6 mm ± 0.2 mm.

[0032] The foam blocks 30 and 31 each have a groove 300 and 310 for positioning the part 2. These grooves 300 and 310 have a depth p of approximately 5 mm and a width 1 of approximately 8 mm. To lighten the foam blocks 300 and 310, these are hollowed out in their center.

[0033] The lower foam block 30 has an upper surface inclined at an angle α relative to the horizontal, i.e. relative to the plane of the lower plate 10. This makes it possible to reduce edge effects and improve the extraction of the iso-surface.

[0034] The tubes 12 are preferably hollow, for example made of carbon, and of low thickness, which makes it possible to reduce edge effects and to improve the impact of artifacts on the part 2. Their external diameter is less than 10 mm ± 1 mm and their thickness less than 2 mm.

[0035] We will now describe how to use tool 1.

[0036] The holding elements 13 are adjusted in height according to the part 2 to be measured and the screws 4 are tightened to immobilize the holding elements 13.

[0037] The part 2 is inserted laterally and placed on the lower foam block 30 in the groove 300, then the upper plate 31 is lowered with its foam block 310 until the groove 310 fits into the upper part of the part 2. The balls 14 must be 10 mm apart from the part in order to avoid ball artifacts being projected onto the part; this safety distance guarantees that the quality of the digital volume of the part is not degraded. When the part 2 has a surface of revolution, this must be at the center of the axis of rotation X of the tool 1.

[0038] Once the part 2 is in place and fixed on the tool 1, the measurements can begin. The measurements are carried out successively by rotating the tool 1 with the part 2, the rotation is carried out in jerks over ranges of approximately 0.2°. The foam blocks constitute supports which prevent any vibration during the rotation of the part 2.

Claims

Claims

1. Tool (1) for holding a part (2) comprising: - a lower plate (10), - an upper plate (11) parallel to the lower plate (10) and movable in translation, - characterized in that each of the lower (10) and upper (11) plates comprises a block of foam (30, 31), the foam having a density of less than 300 kg / m3 and that the two blocks of foam (30, 31) are arranged opposite each other

2. Holding tool (1) according to the preceding claim, characterized in that it comprises at least three balls (14) with a density of less than 3g / m3, preferably less than 2.8g / m3, arranged in a plane parallel to the two plates (10, 11).

3. Holding tool (1) according to the preceding claim characterized in that the balls (14) have a diameter of 6mm ±0.2mm.

4. Holding tool (1) according to one of claims 2 or 3 characterized in that the balls (14) are held in a holding element (13) connected to tubes (12), preferably hollow.

5. Holding tool (1) according to the preceding claim, characterized in that the tubes (12) are hollow and have a wall thickness of less than 3 mm, preferably less than 2 mm.

6. Holding tool (1) according to one of claims 4 or 5 characterized in that the tubes (12) have a density of less than 2g / m3

7. Holding tool (1) according to one of claims 4 to 6 characterized in that the balls (14) are fixed to the tubes (12) by a holding element (13) with a density of less than 300 kg / m3.

8. Holding tool (1) according to one of claims 4 to 7 characterized in that the holding elements (13) are adjustable in height on the tubes (12).

9. Holding tool (1) according to one of the preceding claims, characterized in that the foam block (30) of the lower plate (10) has a support surface inclined relative to the lower plate (10).

10. Holding tool (1) according to the preceding claim, characterized in that the support surface is inclined by 5 to 10° relative to the lower plate (10).

11. Holding tool (1) according to one of the preceding claims, characterized in that the plates (10, 11) are rotating.

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