WO2013004812A1

WO2013004812A1 - Micromachine for mechanical tests of tension and compression type having optimized accessibility

Info

Publication number: WO2013004812A1
Application number: PCT/EP2012/063233
Authority: WO
Inventors: Raphael PESCI; Olivier BOMONT; Marc WARY; Jérémy BIANCHIN; Lionel Simon; Daniel Boehm; Jean-Michel HECKER; Xavier PEIFFERT
Original assignee: Arts
Priority date: 2011-07-06
Filing date: 2012-07-06
Publication date: 2013-01-10
Also published as: FR2977670A1; FR2977670B1

Abstract

The invention relates to a tension micromachine intended to be used in an electronic scanning microscope enclosure or with a diffraction apparatus, comprising two jaws (1) carried by two supports, each jaw (1) being intended to receive an end of a mechanical specimen (4), and means for exerting loads on the supports tending to separate them or to bring them closer together along a longitudinal direction (AL), each jaw (1) comprising a base (2) and a flange (3) for fixing an end (21) of a specimen (4) to the jaw (1) while clamping it between the flange (3) and the base (2) by means of at least two screws (12-5) each passing through the flange (3) and at least a part of the base (2), these two screws (12-15) being situated on either side of the specimen end (21).

Description

TENSION AND COMPRESSION TYPE MECHANICAL TEST MICROMACHINE HAVING OPTIMIZED ACCESSIBILITY

The invention relates to a micromachine for carrying out mechanical tests including traction and / or compression on a mechanical specimen, by installing this micromachine in the enclosure of a scanning electron microscope (SEM) or with a diffraction apparatus, to directly analyze the surface of the specimen while subjected to mechanical stress.

BACKGROUND OF THE INVENTION

In general, such a traction micromachine must imperatively have a small enough space to allow its installation in this type of device. In practice, dimensions smaller than 200 mm × 200 mm × 60 mm are sought for such a micromachine.

When carrying out a test, a mechanical specimen is mounted in this micromachine, and the assembly is installed in the enclosure of a scanning electron microscope or under a diffraction apparatus. The course of the test consists in controlling the traction micromachine to urge the test piece by subjecting it to increasing traction forces, or to increasing elongation at a predetermined speed, at the same time as the surface of the test piece is observed. and analyzed.

The analyzes may be performed in a scanning electron microscope (SEM) or by X-ray diffraction, neutron scattering or synchrotron radiation. Such tests can in particular be carried out under different deformation rates (driving force or displacement): what is more, it is possible to carry out in a scanning electron microscope EBSD maps (Electron BackScatter Diffraction) or EDS (Energy Dispersive Spectoroscopy) while maintaining the loading applied.

In practice, each specimen end is locked in a jaw of the machine so as to be rigidly secured to this jaw, firmly. Given the forces involved, the jaws have relatively large dimensions vis-à-vis the test specimen, while the length of the test piece is between 45 and 60 millimeters, so that the distance between a jaw of the other is relatively weak.

In return, the observation of the surface of the test piece with a diffraction apparatus requires a very clear access to the observed face. Concretely, it is necessary to have an opening angle as large as possible on the upper face of the test piece, whereas in practice this angle is significantly limited by the short useful length of the test piece, the large volume occupied by the jaws at each end of this test piece.

OBJECT OF THE INVENTION

The object of the invention is to provide an arrangement for increasing this opening angle significantly so as to simplify the implementation of such tests.

SUMMARY OF THE INVENTION

For this purpose, the subject of the invention is a traction micromachine intended to be used in an electron microscope chamber, comprising two jaws carried by two supports, each jaw being intended to receive an end of a mechanical test-tube, and means for exerting on the supports efforts tending to separate them from one another or to bring them closer to one another in a longitudinal direction, each jaw comprising a base and a flange for fixing a specimen end to the jaws by clamping it between the flange and the base by means of at least two screws each passing through the flange and at least a part of the base, these two screws being located on either side of the specimen end, the flange comprising a central region; gripping the end of the specimen and two wings each extending each central portion, each leg being traversed by at least one screw, and wherein each flange of the flange is offset from the central region of the flange towards the central portion of the flange. 'base.

The invention also relates to a micromachine as defined above, in which each jaw further comprises a spacer interposing between the specimen end and the base, and / or a spacer interposing between the end specimen and the flange, blocking pins each passing through the flange and each spacer, each spacer having a ridged surface intended to bear against the end of the test piece during tightening.

The invention also relates to a micromachine as defined above, wherein the means for exerting on the movable supports efforts tending to bring them closer or to separate them from one another comprise two ball screw type systems located on both sides of the pair of bits.

The invention also relates to a micromachine as defined above, comprising two fixed guide rails oriented in the longitudinal direction, and wherein the movable supports are connected to the fixed guide rails by slide links oriented in the longitudinal direction.

The invention also relates to a micromachine as defined above, comprising a driving motor of the two ball screw type systems, and chain transmission means connecting this motor to the two ball screw systems. The invention also relates to a micromachine as defined above, wherein each jaw is secured to the movable support which carries it so as to be orientable about a longitudinal axis.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is an exploded view of a jaw according to the invention shown alone;

FIG. 2 is a view from below of a jaw according to the invention in the micromachine according to the invention;

FIG. 3 is an overall view, in perspective, of the micromachine according to the invention;

Figure 4 is a side view of the micromachine according to the invention;

Figure 5 is a top view of the micromachine according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The idea underlying the invention is to provide specific jaws arranged in such a way that the upper face of one specimen is as close as possible to a plane tangent to the upper part of these jaws, these jaws being them. same positioned in an upper region of the traction machine, so as to provide a large opening angle to the upper face of one specimen carried by these jaws.

As shown in Figure 1, the jaw 1 according to the invention comprises a base 2 on which is fitted a flange 3, so as to grip one end or head of a specimen 4 extending in a direction of traction shown by a longitudinal axis AL.

The flange 3 which extends transversely with respect to the longitudinal axis AL has a generally rectangular shape, the transverse direction being represented by an axis indicated by AT in FIG. 1. This flange 3 comprises a central region 5 in the form of a a flat wall, extended by two wings 6 and 7 extending transversely in two opposite directions with respect to the central region 5.

As seen in Figure 1, the two wings 6 and

7 which each have a flat bottom face, are offset relative to the central region 5, in the direction of the base 2 to which the flange 3 is fixed. The lower faces of the wings 6 and 7 are thus at the same level. the other in a vertical direction corresponding to a vertical axis indicated by AV which is normal to the axes AL and AT, but they are located lower than the lower face of the central region 5 of the flange 3.

The upper portion of the base 2 has a shape that is complementary to that of the flange 3 that it receives. This upper portion thus comprises a central region

8 in relief having an upper face located to the right of the central region 5 of the flange 3.

This central region 8 is extended by two lateral portions each having a bearing surface 9, 11 lowered in relation to the central region 8, these bearing faces 9 and 11 thus being located in line with the wings 6 and

7, respectively.

Thus, as shown in Figure 1 where the flange 3 is located above the base 2, the upper portion of the base 2 has a shape which is complementary to that of the flange 3 which itself has a general shape rider, thus fitting into the upper portion of

1 'base 2.

The flange 3 is tightened on the base 2 by means of four screws, marked by 12 to 15. The screws 12 and 13 each vertically traverse the flange 6, at the corresponding holes, and a wedge 17, for screw in the base through its bearing face 9. The screws 14 and 15 vertically pass through the wing 7, at the level of corresponding holes, as well as a wedge 18, to be screwed into the base 2 through its support wall 7.

Complementarily, the jaw is equipped with two spacers 19, 20 which are located between the central region 5 of the flange 3 and the central region 8 of the upper portion of the base 2. Each spacer has a face provided with claws facing the head 21 of the test piece 4 to be received in the jaw, these claws extending transversely so as to avoid longitudinal sliding of the spacer relative to the jaw during the test.

These spacers are held in position in the jaw by means of two pins 22 and 23 oriented vertically. Each pin or rod passes through the flange 3 as well as the two spacers 19 and 20 and the upper face of the central region 8 of the base, at the corresponding holes made in these different components.

When the head 21 of the specimen 4 is in place in the jaw 1, it is thus clamped between the two scratched faces of the spacers 19 and 20 which are themselves compressed between the base 2 and the flange 3, and both Pions 22 and 23 traverse vertically this stack being located on either side of the specimen head 21 along the transverse axis AT.

As can be seen in FIG. 1, the mechanical specimen 4 is in the form of a plane plate of constant thickness which is cut in a contour corresponding to that of the capital letter I, that is to say comprising a body rectangular extended by two ends or heads wider than this body.

The mounting of a test piece in the jaw 1 consists first of all in removing from this jaw 1 the flange 3 as well as the screws 12 to 15, the pins 22, 23, and the upper spacer 20. The test piece is then placed in such a way that the lower face of its head 21 bears on the lower spacer 19 which then rests on the central region 8 of the upper portion of the base 2.

The upper spacer 20 is then positioned on the upper face of the head 21, after which the flange 3 is placed on the assembly, before engaging the two pins 22 and 23 vertically in the corresponding holes so that they through the flange and the spacers and the upper face of the portion 8. The screws 12 to 15 can then be engaged in the corresponding holes, and then tightened so as to completely secure the test piece with the jaw.

As can be seen in FIG. 2, the jaw 1 is secured to a mobile support 24 of the traction machine by means of an indexable link at different angular positions around the longitudinal direction. For this purpose, the base of the jaw 1 comprises a cylindrical or bearing portion 25 protruding from the rear face of this base 2, that is to say the face opposite to the direction in which the test piece 4 extends.

This bearing 25 engages in a corresponding bore of the mobile support 24, thus allowing the jaw to rotate about a longitudinal axis. Complementarily, the base 2 comprises in its lower portion a through hole, oriented parallel to the axis AL, and receiving an indexing pin 26 can thus engage in one of several holes 27-29 made to the face mobile support 24 against which bears the jaw 1 when in place.

When the bearing 25 is in place, it protrudes beyond the movable support 24, to receive a fastening element such as a nut, and / or a sensor measuring the forces exerted by the jaw on the support 24, that is, that is, the tensile forces experienced by the test piece. As will be understood, the assembly of the jaw 1 consists of engaging its bearing 25 in the corresponding hole of the mobile support 24, then to place it at the desired angular orientation around the longitudinal direction, to engage the pin 26 through the base 2 and the movable support, then to mount the fastening element on the part of the bearing protruding from the mobile support 24.

In the example of Figure 2, three orientations of the jaw are possible, spaced from each other by about a quarter turn around the longitudinal direction. Advantageously, the number of holes of the movable support is greater than in the example of the figures, so as to allow any inclination of the jaw, and therefore the specimen, between 30 and 70 degrees in increments of 10 degrees.

The traction machine per se, which is shown as a whole in FIG. 3, indicated by 31, comprises a frame 32 comprising a base 33 having the general shape of a rectangular plate and carrying on its upper surface two transverse fixed supports 34 and 36 located respectively at the front and rear ends of the base 33 relative to the longitudinal direction AL.

In this machine, the test piece 4 mounted is located substantially in the center of the frame, having its first end carried by the jaw 1 and its second end carried by another jaw, marked by 37, and which is of the same type as the jaw. 1. The jaws 1 and 37 are carried respectively by the movable support 24 and the movable support 38, these supports being movable in translation in the longitudinal direction AL.

Each movable support 24, 37 is carried by two ball screw systems extending longitudinally being disposed on either side of the jaws 1 and 37, these jaws being located one along the other. central longitudinal axis AL of the traction machine. The first ball screw system comprises a screw 39 extending longitudinally and having its ends carried by the fixed supports 34 and 36, respectively. This screw comprises successively along the longitudinal direction two threaded portions in the opposite direction and which each extend over a half of the length of the screw.

One of these portions is engaged in a ball bushing 41 which is rigidly secured to the first movable support 24, and the other portion, threaded in the opposite direction, is engaged in another ball bushing 42 which is rigidly secured to the second mobile support 38. Thus, when the screw 39 rotates in one direction, it tends to move the movable supports 24 and 38 away from each other, which corresponds to a tensile test, and when it turns in the opposite direction it tends to bring them closer to one another, which corresponds to a compression test of one specimen.

The second ball screw system is of the same type as the first, it comprises a second screw 43 comprising two threaded portions in opposite directions respectively engaged in a ball socket 44 secured to the first movable support 24 and in another ball socket 46 rigidly secured to the second movable support 38.

The two screws 39 and 43 are rotated by an electric motor 47, of the step type, which is carried by the frame 32 extending longitudinally along the screw 39. The motor shaft 48 of this motor 47 passes through the transverse fixed support 36, and carries at its end a pinion, which rotates jointly screws 39 and 43 through a chain transmission system and toothed wheels.

Under these conditions, when the motor 47 is actuated to rotate in a first direction of rotation, it exerts, via the screws 39 and 43, a pair of rotation tending to move away from each other the movable supports 24 and 38, to urge the test piece 4 in traction. When the motor rotates in the opposite direction, it urges the specimen 4 in compression.

As can be understood, these two ball screw systems, located on either side of the assembly formed by the test piece and the two jaws which bear it, contribute to ensuring that the test piece is subjected to a tensile stress. pure along its longitudinal axis, as they ensure that the two movable supports remain parallel to each other throughout the test.

The micromachine is further provided with additional guide means, ensuring that the movable supports remain oriented perpendicular to their direction of travel during the test, which further contributes to improving a pure traction or pure compression operation.

As can be seen in FIG. 3, these additional guiding means comprise a rail 50 carried by the frame 32 being oriented longitudinally being located transversely to the opposite of the motor 47. This rail carries two shoes 51 and 52, which are longitudinally movable along this rail 50, being connected thereto each by a slide connection oriented along the longitudinal axis. The shoe 51 is rigidly secured to the movable support 24, and the shoe 52 is rigidly secured to the movable support 38.

The micromachine further comprises another rail carrying two other pads, not shown in the figures, and which is located transversely to the opposite of the rail 50, that is to say in the proximity of the motor 47 that it runs. In the same way, the two other unmarked pads are connected to this other rail by longitudinally oriented sliding links, one of these pads being rigidly secured to the movable support 24, the other pad being rigidly secured to the other support mobile 38. With these four pads and these two additional rails, the movable supports 24 and 38 are subject to a displacement in pure longitudinal translation, and they are not likely to incline relative to the transverse to this longitudinal direction.

The micromachine further comprises a force sensor 49, by which the longitudinal forces exerted by the jaw 1 are transferred to the mobile support 24, as previously explained, these forces thus corresponding to the tensile forces to which the test piece 4 is subjected.

The micromachine is further provided with a displacement sensor 56 comprising a body 53 in which a rod 54 slides, these two parts being movable longitudinally with respect to each other.

As can be seen in particular in FIG. 5, the body 53 is secured longitudinally to the first movable support 24, and the rod 54 is secured to the second mobile support 38. This displacement sensor 56 is thus capable of providing accurate information representative of the displacement of the first support 24 relative to the second support 38, that is to say information representative of the elongation of the specimen 4, at any time during the test.

As illustrated in FIGS. 3 to 5, thanks to the jaws according to the invention, the upper face of the test piece 4 is very clear, that is to say that it can be observed at a very wide angle of view, because it is very close to the upper faces of the jaws in the vertical direction, while being located substantially above the screws 39 and 43.

FIGS. 2 to 4 show by A the angular extent in which the upper face of the test piece can be seen, this extent being represented by an angular sector extending over approximately 150 degrees, in a vertical longitudinal plane, that is to say containing the axes AL and AV.

Claims

A mechanical test micromachine (31) for use in a scanning electron microscope chamber or with a diffraction apparatus, comprising two jaws (1, 37) carried by two supports (24, 38), each jaw ( 1, 37) being adapted to receive an end of a mechanical test piece (4), and means for exerting on the supports (24, 38) efforts tending to separate them from each other or to bring them closer together. one of the other in a longitudinal direction (AL), each jaw (1, 37) comprising a base (2) and a flange (3) for attaching a specimen end (21) to the jaw (1). , 37) by clamping it between the flange (3) and the base (2) by means of at least two clamping screws (12-15) each passing through the flange (3) and at least a part of the base (2), these two screws (12-15) being located on either side of the specimen end (21), the flange (3) comprising a central region (5) coming to grip the end of specimen (21) and two wings (6, 7) each extending this central portion (5), each wing (6, 7) being traversed by at least one clamping screw (12-15), and wherein each wing (6, 7) of the flange (3) is offset from the central region (5) of the flange (3) in the direction of the base (2).

2. Micromachine according to claim 1, wherein each jaw (1, 37) further comprises a spacer (19) interposed between the specimen end (21) and the base (2), and / or a spacer (20) interposed between the specimen end (21) and the flange (3), locking pins (22, 23) each passing through the flange (3) and each spacer (19, 20), each spacer (19, 20) having a grooved surface intended to bear on the specimen end (21) during clamping.

3. Micromachine according to claim 1 or 2, wherein the means for exerting on the movable supports (24, 38) efforts tending to bring them closer or to separate them from one another comprise two ball screw type systems. (39, 43) located on either side of the pair of jaws (1, 37).

4. Micromachine according to one of claims 1 to 3, comprising two fixed guide rails (50) oriented in the longitudinal direction (AL), and wherein the movable supports (24, 38) are connected to the fixed guide rails ( 50) by sliding links oriented in the longitudinal direction (AL).

5. Micromachine according to claim 3, comprising a motor (47) for driving the two ball screw type systems (39, 43), and chain transmission means connecting this motor (47) to the two screw systems to ball (39, 43).

6. Micromachine according to one of the preceding claims, wherein each jaw (1, 37) is secured to the movable support (24, 38) which carries it so as to be orientable about a longitudinal axis (AL).