Patent Grant
10611094
This application is the National Stage of International Application No. PCT/FR2015/053654, filed Dec. 18, 2015. The International Application claims priority to French Application No. 14 62943, filed Dec. 19, 2014. The International Application published on Jun. 23, 2016 as WO/2016/097656. All of the above applications are incorporated herein by reference.
The present invention relates to the assembly of two parts, i.e. a part made of a metal material and a part made of an organic-matrix composite material.
It relates in particular to a method for obtaining such an assembly, as well as an assembly consisted of two parts assembled together.
In many fields, in particular that of transport, the multi-material structures become widespread in order to respond to the increasing demands of the users (in particular in terms of lightening of the structures, aesthetics and implementation of new functionalities such as electrical insulation or damping).
It is hence frequent to need to associate parts made of a metal material with parts made of an organic-matrix composite material.
To ensure a satisfying stiffness of two parts assembled together, it is often preferable to make intimate links, generally obtained by welding.
Now, in practice, the metal materials and the organic-matrix composite materials are not compatible between each other for the implementation of a heterogeneous welding.
For this reason, the current technologies for the assembly of such materials are:
But the mechanical assembly technology has in particular for drawback to generate an increase of the structure weight due to the link elements added. Moreover, a drilling of the parts for positioning these link elements may generate zones of weakness, of stress concentration or of fracture ignition.
As for the bonding assembly, it has for drawback to require a surface preparation, and also not to allow a reliable prediction of the long term behaviour of this bonding.
In this context, there exists a need for new technologies for assembling parts made of a metal material and parts made of an organic-matrix composite material.
The present invention relates to a new technology for assembling a part made of a metal material (hereinafter called “metal part”) and a part made of an organic-matrix composite material (hereinafter called “composite part”), which has for interest to be based on a welding assembly.
For that purpose, the present invention provides to add a metal insert in the composite part, at a surface to be welded, a portion of which is arranged in an exposed manner so as to be assembled by a high-speed welding technique to a complementary surface of the metal part.
The method according to the invention comprises the following successive steps:
a) a step of providing said two parts,
wherein said parts each have a surface intended to be welded to a complementary surface of the other part, and
wherein said surface to be welded of said composite part consists, at least partially, in an exposed portion of at least one metal insert that is partially embedded into said composite part,
b) a step of positioning said surfaces to be welded opposite to each other and remote from each other, and
c) a step of projecting (or thrusting or accelerating) at high speed the surface to be welded of the metal part and/or of the exposed portion of the metal insert, against one another, to obtain high-speed pressing of said surfaces to be welded against each other and to obtain a weld between the exposed portion of the metal insert of the composite part and the complementary portion of the surface to be welded of the metal part.
According to other advantageous characteristics, which can be taken in combination or independently from each other:
The present invention also relates to a composite material part, having a surface to be welded that is formed, at least partially, by an exposed portion of at least one metal insert partially embedded into said organic-matrix composite material part.
According to a particular embodiment of this composite material part, the metal insert consists in a plate provided with through-holes having a flared shape on the side of the exposed portion; said metal insert is added into the composite part so that the composite material fills at least a part of said through-holes.
According to another particular embodiment, the composite part has a front face provided with the surface to be welded, and the metal insert of the composite part is located back from the front face of said composite part.
The invention also relates to an assembly comprising a part made of a metal material and a part made of a composite material, wherein said composite part includes at least one metal insert partially embedded into said composite part, wherein said at least one metal insert has an exposed portion at the surface of said composite part that is welded to a complementary portion of the surface of the metal part.
The present invention will be further illustrated, without being limited thereby, by the following description of various embodiments illustrated in the appended figures, in which:
As shown in
For the sake of simplification, these parts 1, 2 are also referred to as “metal part 1” and “composite part 2”, respectively.
By “assembly”, it is understood in particular a link that is permanent, or non-dismountable (subjected to degradation or deterioration), between the two parts 1, 2 at the welding zone 3.
By “assembly”, it is understood in particular a “weld” ensuring a continuity of the nature of the material to be assembled.
By “assembly”, it is advantageously understood an assembly by high-speed pressing, preferably as a magnetic-pulse welding technique.
The metal part 1 is advantageously made of a metal material chosen among steel, aluminium alloy and titanium.
The metal part 1 is advantageously in the form of a plate.
As developed hereinafter, if this metal part 1 includes a portion to be projected 15, at least this portion to be projected 15 includes a thickness comprised between 0.5 and 3 mm.
All or part of the metal part 1, if it is fixed, may have any thickness.
This metal part 1 has in particular two opposite faces (
For its part, the composite part 2 is consisted of a material comprising:
The fibres of the reinforcing material are characterized by their composition (metal, glass, polymer, carbon, vegetable, . . . ), length (short (0.1 to 1 mm), long (1 to 50 mm) or continuous (longer than 50 mm), and arrangement (mat or woven) or multi-material NCF.
The continuous fibres may be arranged parallel to each other, for a unidirectional reinforcement, or according to a predefined angle (45° for example relative to each other), for a multidirectional reinforcement, or also randomly.
By “NCF” or “Non Crimp Fabrics”, it is understood a multi-axial fabric that is consisted of several unidirectional (UD) webs (or layers), sawn together with a thread (generally PET).
For example, a +45°/−45° biaxial NCF material is a fabric consisted of two UD webs: the first web is consisted of a +45° UD and the second web is consisted of a −45° UD. There also exist 0°/90° biaxial NCF materials or 0°/+45°/−45° triaxial NCF materials.
This composite material may also be stratified, formed of several plies (not shown).
By “ply”, it is commonly understood the composite semi-product (fibres plus matrix) in almost-bidimensional shape; it is also understood a thickness composed of parallel strands or “tapes”, linked by matrix.
The organic matrix is advantageously chosen among the thermosetting materials or the thermoplastic materials.
By “thermosetting material”, it is understood in particular:
By “thermoplastic material”, it is understood in particular:
For its part, also, the composite part 2 is advantageously in the form of a plate, having a thickness comprised between 0.5 and 10 mm.
This composite part 2 includes in particular two opposite faces (
According to the invention, the surface to be welded 11 of the metal part 1 is intended to be assembled, by a high-speed projecting technique, with the surface to be welded 21 of the composite part 2.
For that purpose, as illustrated in
To obtain such an assembly (whereas the respective materials are incompatible for a welded link), the composite part 2 provided includes at least one metal insert 5 that is partially embedded at its surface to be welded 21 (
During the high-speed projecting step, the surface to be welded 11 of the metal part 1 is then pressed at high speed against the surface to be welded 21 of the composite part 2, hence causing a phenomenon of welding between the metal insert 5 of the composite part 2 and a complementary portion of the surface to be welded 11 of the metal part 1.
A welding link is hence obtained, with no material adding, between the metal insert 5 and the metal part 1 (corresponding to a continuity of the matter between each other).
The metal insert 5 is hence housed in the composite part 2, at the zone in which it is desired to make the assembly with the metal part 1.
For this reason, according to the case, the metal insert 5 may be placed remote from the edge of the composite panel 2, but also along this edge.
The metal insert 5, and the implantation thereof in the composite part 2, are described in more detail hereinafter in relation with
Herein, the metal insert 5 is implanted into the composite part 2 so as to show an exposed portion 51 that is naked at its surface to be welded 21 (
By “exposed portion”, it is hence understood a portion of the surface of the metal insert 5 that is directly accessible at the surface to be welded 21 of the composite part 2. In particular, this exposed portion 51 of the metal insert 5 must not be covered with the composite material, in particular with the organic matrix.
The metal insert 5 is made of a material that is chosen as a function of the material constituting the metal part 1 to be assembled.
In particular, this material is chosen so as to allow a technique of welding by dynamic pressing between the exposed portion 51 of the metal insert 5 and the surface to be welded 11 of the metal part 1.
For example, this metal insert 5 may be made of steel or an aluminium alloy when the metal part 1 is made of an aluminium alloy.
By way of non-limitative example, other possible combinations are:
Such a metal insert 5, for example in the form of a plate or a platen, includes:
For example, this metal insert has a thickness comprised between 0.1 and 3 mm.
As shown in part A of
In particular, as illustrated in
In this case, the outer face 53 of the metal insert 5 and the front face 2a of the composite part 2 extend in a same plane, or at least approximately in a same plane.
As an alternative, as illustrated in
For that purpose, the metal insert 5 may be added between the plies (not shown) of the composite part 2.
A cut 25 is then made in the overlying plies with respect to the outer face 53 of the metal insert 5, so as to obtain the exposed portion 51 of the metal insert 5 corresponding to the surface to be welded 21 of the composite part 2.
To optimize the cohesion thereof with the composite material, the surface of the metal insert 5 in contact with this composite material, called the “non-exposed surface”, may be prepared so as to obtain an irregular surface.
By “non-exposed surface”, it is meant in particular the inner face 54 and/or the peripheral contour 55 of the metal insert 5.
For example, a shot blasting may be applied to this non-exposed surface of the metal insert 5, so as to increase the surface of contact between the matrix of the composite part 2 and the metal insert 5.
Moreover, the metal insert 5 may consist in a solid part or a perforated part.
For example, as illustrated in
Each of these through-holes 56 is delimited by a contour 561 that has a flared shape from the inner surface 54 to the outer surface 53 (
These through-holes 56 are advantageously filled with the constitutive material of the composite part 2 (organic matrix and possibly the fibres) so as to increase the mechanical pull-out resistance of the metal insert 5 added on the composite part 2.
The percentage of holes 56 is adapted as a function of the expected compromise between, on the one hand, the welded holding between the metal insert 5 and the metal part 1, and on the other hand, the holding of the metal insert 5 in the composite material.
A solid plate, fixed or to be projected, consists in a plate devoid of through-holes as described hereinabove in relation with
The metal insert(s) 5 of the surface to be welded 21 may have different shapes and sizes, as a function in particular of the desired assembly.
The exposed portion 51 thereof hence also consists in an elongated strip of generally rectangular shape, to obtain a continuous welding zone 3.
For example, by way of indication, the metal insert 5 has a length comprised between 10 and 100 mm and a width comprised between 10 and 30 mm.
Each metal insert 5 has herein a generally square or rectangular shape; its exposed portion 51 hence also consists in a square or rectangular shape.
For example, by way of indication, each metal insert 5 has a length comprised between 20 and 40 mm and a width comprised between 20 and 40 mm.
The composite part 2, with its added metal insert 5, may be obtained by any suitable method.
For example, as illustrated in
Such a method is possible in the case of a composite part 2 made of a thermoplastic material.
Such an operation of inclusion consists in:
In particular, the metal insert 5 is heated up to a temperature that is function of the melting temperature of the matrix of the composite part 2. More precisely, this metal insert 5 is brought to a temperature equal to or higher than this melting temperature.
For example, the metal insert 5 is heated to a temperature of 260° C., with the application of a pressure of 27 bars, for a matrix made of extruded polyamide 6.6.
This assembly could also be obtained by any other method of assembly, for example by seaming (the metal insert 5 is seamed with the pre-impregnated fabrics before consolidation).
Starting from such a composite part 2 with its metal insert 5, as described hereinabove, the step of relative positioning of the two parts 1, 2 is implemented so that the surfaces to be welded 11, 21 extend opposite each other and at a distance advantageously comprised between 0.5 and 1.5 mm.
The high-speed projecting step is for its part implemented so as to obtain a high-speed pressing of the surfaces to be welded 11, 21 against each other and to obtain a weld between the exposed portion 51 of the metal insert 5 of the composite part 2 and the complementary portion of the surface to be welded 11 of the metal part 1.
By “high speed”, it is understood in particular a speed comprised between 150 m/s and 400 m/s.
This projecting step is advantageously implemented through a pulse that is applied to a portion to be projected 15 of the metal part 1 and/or to the exposed portion 51 of the metal insert 5 (hence forming the portion to be projected of this metal insert 5).
Herein, this portion to be projected 15 of the metal part 1 has two opposites surfaces:
A projecting force is hence applied to this portion to be projected 15, in a direction extending from the its rear surface 152 to its front surface 151 and in a direction oriented towards the surface to be welded 21 of the composite part 2.
The projecting step is advantageously obtained through magnetic-pulse projecting means 7.
A welding cycle, conventional per se, may be summarized by the 6 following steps:
This projecting phenomenon is hence the consequence of an extremely rapid transfer of energy, the power of this process being of the order of several thousands of megawatts, but over very short durations.
This process is practically adiabatic and there is not really heat transfer; the welding between the metal insert 5 and the metal part 1 is performed “in cold state”.
Indeed, the materials advantageously reach no more than 30° C. There is hence no thermally-affected zone in the composite material, which does not lose its properties.
The magnetic-pulse welding process also constitutes a welding method of the “Solid State” type, which means that the material is not melted during the welding cycle.
In the case of a non-electrically conductive metal part, the rear face 152 of the portion to be projected 15 is then advantageously covered with an electrically conductive material forming a “thruster”, for example made of an aluminium alloy, so as to obtain the desired projecting effect.
As an alternative, it may be contemplated to use any other technique adapted to produce a high-speed projecting, for example through a mechanical action or through a laser shock.
In the different cases, under the effect of the propulsion force:
This high-speed pressing then generates a phenomenon of welding between the exposed portion 51 of the metal insert 5 of the composite part 2 and the complementary portion of the surface to be welded 11 of the metal part 1.
A multi-material assembly is hence obtained, comprising a part 1 made of a metal material and a part 2 made of an organic-matrix composite material, wherein said composite part 2 includes a metal insert 5 partially embedded into said composite part 2, which metal insert 5 includes an exposed portion 51 at the surface 2a of said composite part 2, which is welded to a complementary portion of the surface 11 of the metal part 1.
Several embodiments are contemplatable to obtain this positioning and this projecting, as described in more details hereinafter in relation with
In these different embodiments, the projecting step is advantageously implemented so as to obtain a progressive pressing of the surfaces to be welded 11, 21 against each other, to ensure an expulsion of the oxides.
By “progressive pressure”, it is understood in particular a contact between the surfaces to be welded that begins by one spot, then extends along a line, before propagating until the whole surface is in contact (welding surface).
According to a first embodiment illustrated in
The front faces 1a, 2a of the two parts 1, 2, and their respective surfaces to be welded 11, 21, are then separated by a distance equal to the height of the added shims 8.
The projecting step will then propel at high speed the portion to be projected 15 of the metal part 1, towards the surface to be welded 21 of the composite part 2, in the space separating their respective front faces 1a, 2a (
The portion to be projected 15 hence finally has a convex arrangement with respect to the front face 1a of the metal part 1.
According to another embodiment illustrated in
The boss is in particular arranged so as to keep a distance comprised between 0.5 and 1.5 mm between its surface to be welded 11 and the surface to be welded 21 of the composite part 2.
The projecting step will hence propel at high speed the boss-shaped portion to be projected 15 of the metal part 1 towards the surface to be welded 21 of the composite part 2 (
The portion to be projected 15 hence finally has a planar or practically planar arrangement with respect to the metal part 1 (
According to a third embodiment illustrated in part A of
The metal part 1 hence includes:
The projecting step will hence propel at high speed the folding-shaped portion to be projected 15 of the metal part 1 towards the surface to be welded 21 of the composite part 2 (
The composite part 2 is hence finally taken in sandwich between the rear portion 16 and the front portion 17 of the metal part 1 (
According to a fourth embodiment illustrated in
The front faces 1a, 2a of the two parts 1, 2 bear against each other, and their respective surfaces to be welded 11, 21 are then separated by a distance equal to the height of the overlying plies with respect to the outer face 53 of the metal insert 5.
This height also corresponds to the height of the cut 25 formed in the above-mentioned overlying plies.
The projecting step will hence propel at high speed the portion to be projected 15 of the metal part 1, towards the surface to be welded 21 of the composite part 2, in the space separating their respective surfaces to be welded 11, 21 (
The portion to be projected 15 hence finally has a convex arrangement with respect to the front face 1a of the metal part 1, extending within the cut 25.
In this case, the distance between the surfaces to be welded 11, 21 allows a direct welding, without using insulators or studs.
Such a metal insert 5, similar to that described hereinabove in relation with
The metal insert 5 advantageously includes through-holes 56 as developed hereinabove in relation with
The opposite integral mounting tabs 57 (connected to the two great sides) are herein divergent relative to each other, moving apart from each other from the metal insert 5.
These mounting tabs 57 are also flexible, so as to be folded over at the time of the mounting of the metal insert 5 onto the composite part 2.
In this respect,
Such a method is possible in the case of a composite part 2 made of a thermoplastic material.
Such an operation of inclusion consists in:
Here again, the metal insert 5 is heated up to a temperature that is function of the melting temperature of the matrix.
During this last step, the integral mounting tabs 57 get into the thickness of the composite part 2 to go out on the side of its rear face 2b, until the outer face 53 of the metal insert 5 extends in the plane, or at least approximately in the plane, of the front face 2a of the composite part 2.
The protruding portion 571 of these integral mounting tabs 57 (going out on the side of the rear face 2b of the composite part 2) are then folded over against the rear face 2b of the composite part 2, advantageously by means of an adapted shape of the fixed portion 61 of the heating press 6.
Here again, the composite part 2 of
The metal insert 5 of the composite part 2 (and in particular its outer face 53) is located back from the front face 2a of said composite part 2, within a blind hole 26 open at said front face 2a and closed at the rear face 2b.
The metal insert 5 is implanted into the composite part 2 so as to have—the exposed portion 51 that is naked at its surface to be welded 21, and—a peripheral portion 58 embedded into the composite material.
The front faces 1a, 2a of the two parts 1, 2 bear against each other; and their respective surfaces to be welded 11, 21 are also separated by a distance equal to the height separating the outer face 53 of the metal insert 5 and the front face 2a of said composite part 2.
This recess advantageously corresponds to the overlying plies with respect to the outer face 53 of the metal insert 5. This height then corresponds to the height of the cut 25 formed in the above-mentioned overlying plies.
The projecting step will hence consist in propelling at high speed the surface to be welded 21 of the composite part 2 (herein the exposed portion 51 of the metal insert 5) towards the surface to be welded 11 of the metal part 1, in the space separating their respective surfaces to be welded 11, 21 (
The projecting force is applied to this exposed portion 51, in a direction extending from its inner face 54 to its outer surface 53 and in a direction oriented towards the surface to be welded 11 of the metal part 1.
The projecting step is advantageously obtained through magnetic-pulse projecting means 7, arranged opposite the rear face 2b of the composite part 2 and the inner face 54 of the metal insert 5.
The exposed portion 51 of the metal insert 5 hence finally has a convex arrangement, towards the front face 1a of the metal part 1 and the front face 2a of said composite part 2, extending within the cut 25.
In this case also, the distance between the surfaces to be welded 11, 21 allows a direct welding, without using insulators or studs.
Generally, the present invention has for interest to allow an efficient assembly between a metal part and a composite part, without affecting their respective properties.
This technical solution has moreover the interest to allow the implementation of conventional means, commonly used for assembling two metal parts together.
| Number | Date | Country | Kind |
|---|---|---|---|
| 14 62943 | Dec 2014 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2015/053654 | 12/18/2015 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2016/097656 | 6/23/2016 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6226152 | Tanaka | May 2001 | B1 |
| 9553296 | Dai | Jan 2017 | B1 |
| 20040028858 | Schnell | Feb 2004 | A1 |
| 20040155030 | Schmidt | Aug 2004 | A1 |
| 20130140853 | Neumann | Jun 2013 | A1 |
| Number | Date | Country |
|---|---|---|
| 1911940 | Sep 1970 | DE |
| 102006024604 | Nov 2007 | DE |
| 102011106700 | Mar 2012 | DE |
| 102011106700 | Mar 2012 | DE |
| 2998210 | May 2014 | FR |
| Entry |
|---|
| International Search Report, dated Apr. 6, 2016, which issued during the prosecution of International Patent Application No. PCT/FR2015/053654, which corresponds to the present application. |
| Written Opinion, dated Apr. 6, 2016, which issued during the prosecution of International Patent Application No. PCT/FR2015/053654, which corresponds to the present application. |
| Number | Date | Country | |
|---|---|---|---|
| 20180050496 A1 | Feb 2018 | US |
