FR3146089A1 - THERMOCOMPRESSION DEVICE FOR THE MANUFACTURE OF MECHANICAL PARTS - Google Patents

Abstract

The invention relates to a thermocompression device for manufacturing mechanical parts comprising a first part and a second part configured to form, by nesting, a cavity having the shape of a mechanical part to be manufactured and a first interstitial zone, formed between the first part and the second part when they are nested, and extending in a first direction. The thermocompression device further comprises at least one second interstitial zone, formed between the first part and the second part when they are nested, extending between the cavity and the compression chamber, in a second direction distinct from the first direction. Figure for abstract: Figure 5

Description

THERMOCOMPRESSION DEVICE FOR THE MANUFACTURE OF MECHANICAL PARTS

The invention relates to the field of manufacturing mechanical parts and it concerns in particular a thermocompression device for this manufacturing.

It is known to manufacture certain mechanical parts, in particular mechanical parts of aircraft turbomachines, by a molding process called thermocompression, that is to say a process in which material is put under pressure, at a given temperature, in a mold (i.e. in a cavity formed in the mold) having the shape of a part to be manufactured in order to ultimately obtain said part.

There shows an embodiment of a mold 101 (or thermocompression device) according to the prior art and the shows an enlargement of a portion of this device 101. The thermocompression device 101 comprises a first portion 103, also called a punch, and a second portion 105, also called a die. The punch 103 and the die 105 are configured to fit into each other and form within them, once fitted, a cavity 107 having predetermined dimensions corresponding to those of the mechanical part to be manufactured.

In the example shown, the punch 103 comprises a system 109 for injecting molten polymer into the cavity 107 while the die 105 is configured to receive a fibrous preform 111 for the purpose of manufacturing a mechanical part in composite material.

In particular, as it is represented in a simplified manner in the , during a first step of manufacturing the part (shown in the left part), the molten polymer is injected into the cavity 107. Then, during a second step (shown in the right part), under the combined effect of a determined temperature to which the device 101 is brought and the pressure generated in the cavity 107 by the fitting of the punch 103 into the die 105, the molten polymer spreads into the cavity and diffuses into the fiber preform so as to form the mechanical part 117 made of composite material.

In the example shown, the punch 103 is inserted into the die 105 in the direction symbolized by the arrows 115 until the desired pressure is generated in the cavity 107 to form the mechanical part 117.

Furthermore, in addition to the elements already described, the thermocompression device 101 also comprises compression chambers 113. These are interstitial zones, distinct from the cavity, formed between the punch 103 and the die 105 when they are fitted together and which extend in the direction of insertion of the punch 103 into the die 105.

Indeed, at the level of the respective walls of the punch 103 and the die 105 which slide along one another when the punch 103 is inserted into the die 105, there is an interstitial zone in which material used for the manufacture of the part is or may be engaged. Thus, each compression chamber 113 is capable, during the manufacture of the part, of filling up in whole or in part with the material of the part under the effect of the pressure generated in the device 101.

The filling of the compression chamber 113 causes the existence of a protrusion of the part which is finally extracted from the device. This protrusion extends in the direction of the compression chamber 113.

There schematically shows an example of a part 117 extracted from a thermocompression device such as the thermocompression device 101 described with reference to FIGS. 1 and 2. The burrs 301 are defects in the part 117 which is extracted from the thermocompression device which must subsequently be removed to obtain a finished part with the desired dimensions.

In particular, obtaining the finished part requires an operation called deburring which consists of removing existing burrs. As illustrated in , such an operation can, for example, be carried out by a human operator using a specific tool to remove existing burrs. In any case, given the shape and arrangement of the burrs generated by such a device, deburring is a complex and lengthy operation.

The present invention provides a solution to these drawbacks.

Thus, one objective of the invention is to offset the compression chamber(s) of a thermocompression device, by introducing an intermediate zone between the cavity of the device and the compression chamber, so as to obtain a part that is easier to deburr and, consequently, so as to simplify the manufacture of a finished part.

For this purpose, the invention according to a first aspect relates to a thermocompression device for the manufacture of mechanical parts comprising:

- at least a first part and a second part configured to form, by fitting said first part into said second part in a first direction, a cavity having the shape of a mechanical part to be manufactured; and,

- at least one first interstitial zone called a compression chamber, distinct from the cavity, formed between the first part and the second part when said first part and said second part are fitted together, and extending longitudinally in the first direction,

said thermocompression device being characterized in that it further comprises at least one second interstitial zone called a burr zone, formed between the first part and the second part when said first part and said second part are fitted together, and extending longitudinally between the cavity and the first interstitial zone, in a second direction distinct from the first direction, preferably perpendicular to said first direction.

Thus, thanks to the fact that the compression chamber is offset from the end of the part by the addition of a small width of material pinching with zero or very low final thickness, the invention makes it possible to obtain burrs which extend in the extension of the shape of the part and which are therefore easier to eliminate by a simple finishing operation or even to completely eliminate the very existence of burrs at the end of thermocompression.

The thermocompression device according to the invention may comprise one or more of the following features, taken in isolation from one another or in combination with one another:

- the mechanical part to be manufactured is a mechanical part of an aircraft turbomachine.

- the device further comprises a system for injecting a liquefiable material into the cavity, formed in the first part and comprising at least one conduit passing through said first part from an external surface of said first part to the cavity so as to allow the injection of said liquefiable material from outside the thermocompression device into said cavity.

- the at least one burr zone has a substantially constant thickness in the second direction.

- the at least one burr zone has an increasing thickness, in the second direction, from the cavity to the compression chamber.

- the at least one burr zone has a decreasing thickness, in the second direction, from the cavity to the compression chamber.

- the at least one burr zone has a length in the second direction of between 0.5 mm and 10 mm, preferably of between 0.5 and 4 mm.

- the thermocompression device comprises a number of parts greater than or equal to 4, positioned side by side according to a bidirectional matrix, forming cavities between each part when said parts are fitted together, so as to manufacture a mechanical part in the form of a grid, preferably a thrust reverser grid for an aircraft nacelle.

- at least one burr zone is not located at an edge of the cavity.

- the liquefiable material is a polymer and the second part is configured to receive a fibrous preform so that said thermocompression device makes it possible to manufacture a mechanical part in composite material, for example a part of a propulsion unit or a grid-type part.

• positionnement d’une matière comportant au moins une structure fibreuse entre la première et deuxième partie ;
• compression de la matière par déplacement de la première partie vers la seconde partie ;
• consolidation de la matière par solidification ; et,
• démoulage de la pièce.

Furthermore, the invention according to a second aspect relates to a method of using a device according to the first aspect comprising the steps of:

• positioning of a material comprising at least one fibrous structure between the first and second part;
• compression of the material by displacement of the first part towards the second part;
• consolidation of matter by solidification; and,
• demolding the part.

The present invention will be better understood and other details, characteristics and advantages of the present invention will appear more clearly on reading the description of a non-limiting example which follows, with reference to the appended drawings in which:

there is a schematic representation of an embodiment of a thermocompression device according to the prior art;

there is a schematic representation of an embodiment of a part of a thermocompression device according to the prior art;

there is a schematic representation of a mechanical part manufactured by a thermocompression device according to the prior art;

there is an illustration of the deburring of a mechanical part manufactured by a thermocompression device according to the prior art;

there is a schematic representation of a first embodiment of a thermocompression device according to the invention;

there is a schematic representation of a second embodiment of a thermocompression device according to the invention;

there is a schematic representation of a third embodiment of a thermocompression device according to the invention;

there is a schematic representation of a mechanical part manufactured by a thermocompression device according to the invention;

there is a schematic representation of a fourth embodiment of a thermocompression device according to the invention; and,

there is a step diagram of an embodiment of a method of using the device according to the invention.

In reference to the , we will now describe an embodiment of a thermocompression device 501 according to the invention. The represents only a part of the device located at an edge of a cavity of the device described below.

Device 501 is a thermocompression device for the manufacture of mechanical parts such as, for example, mechanical parts of aircraft turbomachines.

The device 501 comprises a first part 503 and a second part 505 which are configured to form, by nesting the first part 503 in the second part 505 in a first direction X, a cavity 507 having the shape of a mechanical part to be manufactured. In different embodiments of the invention, the nesting of the two parts of the device may involve the movement of a part which is movable towards the other part which is fixed or the movement of two movable parts towards each other, in all cases in the first direction X.

The device 501 further comprises an interstitial zone 509 called a compression chamber which is distinct from the cavity and formed between the first part and the second part when they are nested. This compression chamber 509 extends longitudinally in the direction X.

In particular, as can be seen in FIG. 5, the compression chamber 509 is located at the level of walls of the first part 503 and the second part 505 which move opposite each other and along each other when the two parts 503 and 505 are fitted together.

The exemplary compression device 501 shown in only shows a single compression chamber 509, however those skilled in the art will appreciate that the invention applies, in general, to a thermocompression device comprising a number of compression chambers greater than or equal to 1.

The thermocompression device 501 further comprises at least one second interstitial zone 511 called a burr zone which is formed between the first part 503 and the second part 505 when they are nested. The burr zone extends longitudinally between the cavity 507 and the compression chamber 509 in a second direction Y distinct from the first direction X.

The Y direction can form with the X direction an angle between 30° and 90°, preferably close to 90°. In the non-limiting example shown, the second Y direction is perpendicular to the first X direction and extends substantially in line with the shape of the cavity 507.

Thus, in the thermocompression device 501, a liquefiable material (during the manufacture of the part) pressurized in the cavity 507 can flow into the compression chamber 509 via the flash zone 511.

In different configurations of use of the device 501, the material used to manufacture the mechanical part can either be positioned beforehand between the first part 503 and the second part 505 before they are fitted together, or injected, in whole or in part, between the two parts, during compression.

Thus, the thermocompression device 501 may comprise a system for injecting a liquefiable material into the cavity 507 such as that shown in .

Such an injection system may be formed in one of the two parts of the device, for example the first part 503, and comprise at least one conduit passing through this part from an external surface of this part to the cavity so as to allow the injection of the liquefiable material from the outside of the thermocompression device into the cavity.

As a non-limiting example, the liquefiable material injected into the cavity may be a polymer and one of the parts of the device, for example the second part 505, may be configured to receive a fibrous preform so that the thermocompression device makes it possible to manufacture a mechanical part made of composite material.

There shows an example of a mechanical part 701 obtained from the thermocompression device 501. The part 701 comprises two burrs 703. Each burr 703 has a portion which extends substantially in the extension of the shape of the part 701 (generated by the flow of the material in the burr zone) and a portion which extends substantially perpendicular to the other (generated by the flow of the material in the compression chamber).

Advantageously, the profile of the burrs thus obtained simplifies deburring by avoiding the need for complex operations to remove excess material and/or reduces the number of operations necessary to achieve the final shape of the part.

In addition, better control of the burr profile (i.e. their shape and location) also simplifies the manufacturing of mechanical parts with complex shapes at their ends.

Typically, each burr zone 511 may have a length in the second direction Y of between 0.5 mm and 10 mm, for example of between 0.5 and 4 mm, for example equal to 1 mm to obtain the effect (of simplification of the deburring) indicated above without requiring the use of too much space within the thermocompression device.

Furthermore, the thermocompression device may be configured so that each flash zone 511 is not located at an edge of the cavity 507 (as is the case in the example illustrated in ) in order to avoid damaging the part during deburring or making deburring too complex. Furthermore, as also illustrated by the , the burr being offset from the edge of the part, it does not impact the geometry of the molded part in this area.

In any case, the person skilled in the art will know how to adapt the position and dimensions of each burr zone according to the objectives sought.

For example, in different embodiments of the invention each burr zone 511 may have either a substantially constant thickness along the second direction Y as shown in , or an increasing thickness, according to the second direction Y, from the cavity 507 to the compression chamber 509 as shown in , or even a decreasing thickness, according to the second direction Y, from the cavity 507 to the compression chamber 509 as shown in .

Advantageously, a configuration such as that shown in the allows a more pronounced line of weakness to be created (at the junction between the cavity and the burr zone) to further facilitate deburring, whereas a configuration such as that shown in helps facilitate the re-engagement of material into the cavity.

There illustrates yet another embodiment of a thermocompression device 801 according to the invention. In the example shown, the thermocompression device 801 comprises 4 parts 803, 805, 807 and 809 which are positioned side by side according to a so-called bidirectional matrix, that is to say a matrix which comprises two intersecting directions, which can form, for example, square, rectangular, diamond-shaped elements, or even triangles.

All parts form cavities in pairs (i.e. a cavity between each pair of parts) when they are nested. Furthermore, the cavities are all connected to each other and thus form a single overall cavity 811 filled by the liquefiable material when the latter is injected into the overall cavity 811 under pressure.

Such a device, with a number of parts greater than or equal to 4, positioned in this way, makes it possible in particular to manufacture a mechanical part in the form of a grid, such as for example a thrust reverser grid for an aircraft turbomachine nacelle.

Furthermore, as with the embodiments described above, each cavity formed between a pair of portions of the thermocompression device 801 comprises at least one compression chamber 813 and a flash zone 815 which enable flashes to be generated whose shape and arrangement facilitate removal.

Finally, in a variant of the thermocompression device 501, the parts of the device themselves can be either solid elements which can be broken down into pieces so that they can be easily removed from the part, or liquefiable elements, which are removed from the part after compression (for example by heat to cause them to melt or by dissolution in a liquid).

In reference to the , we will now describe a method 901 of using the device described above.

Step 903 consists of positioning a material comprising at least one fibrous structure (i.e. a preform) between the first and second parts. The fibrous structure may be pre-impregnated (i.e. it incorporates a quantity of liquefiable material within it) or dry (without integrating liquefiable material).

Furthermore, as discussed above with reference to the device, in the various embodiments of the method, liquefiable material may be injected directly into the cavity formed between the first part and the second part by means of an injection system after they have been fitted together or all or part of the material may have been positioned between the first and second parts before they are fitted together.

Step 905 consists of compressing the material by moving the first part towards the second part. This therefore involves fitting the first part into the second part by translating the first part in the X direction.

Step 907 consists of the consolidation of the material by solidification. Concretely, the material which coats the fibers (of the fibrous structure) solidifies and thus gives the part its final shape (with possible burrs).

Step 909 consists of demolding the part. In addition, depending on the final state of the demolded part, a deburring step (simplified thanks to the device and the method) can be carried out to obtain the finished part.

Claims (11)

Thermocompression device (501) for the manufacture of mechanical parts comprising:
- at least a first part (503) and a second part (505) configured to form, by fitting said first part (503) into said second part (505) in a first direction (X), a cavity (507) having the shape of a mechanical part to be manufactured; and,
- at least one first interstitial zone (509) called a compression chamber, distinct from the cavity (507), formed between the first part (503) and the second part (505) when said first part (503) and said second part (505) are fitted together, and extending longitudinally in the first direction (X),
said thermocompression device (501) being characterized in that it further comprises at least one second interstitial zone (511) called a burr zone, formed between the first part (503) and the second part (505) when said first part (503) and said second part (505) are fitted together, and extending longitudinally between the cavity (507) and the first interstitial zone (509), in a second direction (Y) distinct from the first direction (X), preferably forming an angle of between 30° and 90° relative to said first direction (X). Thermocompression device (501) according to claim 1, further comprising a system for injecting a liquefiable material into the cavity (507), formed in the first part (503) and comprising at least one conduit passing through said first part (503) from an external surface of said first part (503) to the cavity (507) so as to allow the injection of said liquefiable material from the outside of the thermocompression device (501) into said cavity (507). Thermocompression device (501) according to claim 2, wherein the liquefiable material is a polymer and the second part (505) is configured to receive a fibrous preform so that said thermocompression device (501) makes it possible to manufacture a mechanical part in composite material. Thermocompression device (501) according to any one of claims 1 to 3, in which the at least one burr zone (511) has a substantially constant thickness in the second direction (Y). Thermocompression device (501) according to any one of claims 1 to 3, in which the at least one burr zone (511) has an increasing thickness, in the second direction (Y), from the cavity (507) to the compression chamber (509). Thermocompression device (501) according to any one of claims 1 to 3, in which the at least one burr zone (511) has a decreasing thickness, in the second direction (Y), from the cavity (507) to the compression chamber (509). Thermocompression device (501) according to any one of the preceding claims, in which the at least one burr zone (511) has a length in the second direction (Y) of between 0.5mm and 10mm, preferably of between 0.5mm and 4mm. Thermocompression device (501) according to any one of the preceding claims, said thermocompression device (501) comprising a number of parts (803, 805, 807, 809) greater than or equal to 4, positioned side by side in a bidirectional matrix, forming cavities between each part when said parts (803, 805, 807, 809) are nested, so as to manufacture a grid-shaped mechanical part. Thermocompression device (501) according to any one of the preceding claims, wherein the at least one burr zone (511) is not located at an edge of the cavity (507). Thermocompression device (501) according to any one of the preceding claims, in which the mechanical part to be manufactured is a mechanical part of an aircraft turbomachine, for example a part of a propulsion assembly or a grid-type part. A method (901) of using the compression device (501) according to any preceding claim, said method (901) comprising the steps of:
- positioning (903) of a material comprising at least one fibrous structure between the first and second part;
- compression (905) of the material by moving the first part towards the second part;
- consolidation (907) of the material by solidification; and,
- demolding (909) of the part.