Assembly of parts made from thermoplastic material and method for assembling such parts by means of thermoplastic riveting

Abstract

This invention relates to an assembly of regions (10a, 10b) of composite parts (2a, 2b) with thermoplastic matrix, including a plurality of riveting points along regions (10a, 10) of the parts that overlap through the superposition of two faces (12a, 12b) of these regions (10a, 10b) which are positioned facing one another, each region (10a, 10b) having another, opposite, face (11a, 11b) which remains visible with the part (2a, 2b). The riveting is performed using assembly ties (6) made of thermoplastic resin-based composite material compatible with the material of the parts (2a, 2b). These ties (6), which are made up at least in part of a stitch of backstitch produced using a filament of a material selected from a fiber coated with aramid resin, a carbon fiber and a glass fiber, are embedded in said regions (10a, 10b) and passing right through the same with an orientation comprised between 30 and 90 with respect to their faces (11a, 11b; 12a, 12b).

Claims

1. An assembly method for composite parts with a thermoplastic-matrix material, using thermoplastic riveting, the method comprising the following steps: overlapping first and second parts by superposing two edge faces of regions facing one another, each part having another opposite face, which remains visible; bringing a holed heating panel into position on each visible face in such a way that the holes are positioned facing one another; heating the visible faces to a temperature higher than the melting point of the thermoplastic-matrix material of the parts to begin melting regions of the superposed faces; inserting at least one holing spike through a first holed heating panel, with successive holing of the first and of the second parts, creating at least one cylindrical bore; withdrawing the holing spike by continuously moving in the same direction of the insertion or in the opposite direction of the insertion; replacing one of the holed heating panels with a non-holed heating panel; and removing a second holed heating panel, thus uncovering a visible face; wherein an assembly tie comprising a strand made of a composite material with a thermoplastic matrix is then inserted into the cylindrical bore; wherein the strand is cut off in situ at a correct height; wherein a second non-holed heating panel is positioned on the uncovered face, also covering the cut strand; wherein the two non-holed heating panels then compress and heat the two edges of the parts made of thermoplastic material.

2. The assembly method as claimed in claim 1, wherein the assembly tie is made of a thermoplastic material having a reinforcing element that has a shape that complements the at least one cylindrical bore.

3. The assembly method as claimed in claim 2, wherein, in the event that the assembly tie is a reinforcing element, the reinforcement element is carried through after the holing spike which emerges from the thermoplastic material by traveling in the direction in which is introduced.

4. The assembly method as claimed in claim 1, wherein the assembly tie protrudes beyond the visible face of the first part and is cut before consolidation tooling is installed.

5. The assembly method as claimed in claim 1, wherein provision is made for automating steps of simultaneous assembly of several parts that are to be assembled.

6. The assembly method as claimed in claim 5, wherein a holing grid for the holing of the parts is used for simultaneously holing the parts using a plurality of holing spikes.

Description

DESCRIPTION OF THE FIGURES

(1) Further information, features and advantages of the present invention will become apparent from reading the following nonlimiting description given with reference to the attached figures which respectively depict:

(2) FIG. 1: a view of one example of steps of the method for assembling two parts made of thermoplastic material by thermoplastic riveting;

(3) FIG. 2: a variant of the method of FIG. 1, using a stitch;

(4) FIG. 3: a view of riveting according to one exemplary embodiment of the invention using a staple; and

(5) FIG. 4: a variant of the method of FIG. 1, using a cylindrical bore for a strand with a countersunk head and an end that is domed by means of a rivet-heading tool.

(6) In the figures of this document, elements that are identical or analogous are identified by the same reference sign which refers to the passage(s) of the description in which it is mentioned.

DETAILED DESCRIPTION

(7) FIG. 1 gives an example in seven main steps of the method according to the invention for assembling, by thermoplastic riveting, two parts 2a, 2b of the architecture of an airplane door made of thermoplastic material. In this example, the parts 2a, 2b are assembled via their end regions delimited by their edges 10a and 10b, but the method may be applied to the assembly of parts in regions situated at the center of these parts. The thermoplastic material here is PEEK (phenylene polyetheretherketone). This riveting involves the use of a holing spike 1, two holed heating panels 3a and 3b for the passage of the holing spike 1, and two non-holed heating panels 30a and 30b.

(8) This method proceeds according to the following steps: Step 1: superposing the edges 10a and 10b of the parts 2a, 2b made of thermoplastic material, these edges 10a, 10b therefore each having: a visible edge face 11a, 11b and a non-visible central edge face 12a, 12b pressed against the other central edge face 12b, 12a; and positioning on each visible edge face 11a, 11b a holed heating panel 3a and 3b; the holes P2 and P3 arein this exampleperpendicular to the edge faces 11a, 11b and 12, 12b, but could be inclined with respect to these faces, particularly in the range of orientations comprised between 30 to 90; Step 2: using the holed heating panels 3a and 3b to heat the edges 10a and 10b of the two parts 2a, 2b made of thermoplastic material, this heating being performed to a temperature a few degrees higher than the melting point of the thermoplastic material; the non-visible central faces 12a and 12b thus progressively beginning to melt together; Steps 3 and 4: inserting a holing spike 1 (arrow F0) through the holed heating panels 3a and 3b, with a first edge 10a followed by a second edge 10b of these two parts made of PEEK being holed almost simultaneously in order to create a cylindrical bore 5 with a circular base in this example; the holing spike 1 is then withdrawn either by continuing to move it in the same direction as its direction of insertion (forward) as in the example, or by moving it in the opposite direction (in reverse); Step 5: replacing one of the holed heating panels (in this exemplary embodiment, the first panel 3b) with a non-holed heating panel 30b so as to allow even heating of the two edges 10a and 10b; and then replacing the second holed heating panel 3a, thus uncovering the visible edge face 11a; a strand 6 made of a composite material with a thermoplastic matrix, in this example made of PEEK, is then inserted into the cylindrical bore 5 using a tool 60 (arrow F1); Step 6: the strand 6 is cut off in situ at the correct height, namely so that it barely protrudes beyond the edge face 11ausing a tool 61 (arrow F2); Step 7: a non-holed heating panel 30a is positioned on the uncovered face 11a, also covering the cut strand 6; the two non-holed heating panels then compress and heat the two edges 10a and 10b of the parts made of thermoplastic material; in this way, this heating allows the two non-visible central faces 12a and 12b and, advantageously, the laminated reinforcing material with high mechanical performance (in this example made of PEEK and carbon fiber) of the assembly parts to melt together with the material of the two edges 10a and 10b.

(9) FIG. 2 shows a variant of the method of FIG. 1 regarding the use of a stitch, produced using two filaments 14 and 15. These filaments are made of fibers coated with thermoplastic resin, of aramid resin of the Kevlar type in this example, which have a high tensile strength. Alternatively, the Kevlar fiber may be replaced with carbon fiber or glass fiber. Steps 1 to 4 of FIG. 1 are identical to those of the method using a strand. Then, for the use of a stitch (or stitching), a stitching needle 13 is introduced into the cylindrical bore 5 from the side of the edge 10a (step 5). The stitching needle 13 carries the filament 14, and this filament 14 is knotted with the other filament 15 which runs along the edge 10b (step 6). Other types of stitch can also be used (lock stitching, etc.).

(10) FIG. 3 illustrates one example of the use of a staple 20 in the context of the method of assembling the two edges 10a and 10b of the parts made of thermoplastic material using thermoplastic riveting. A staple 20, made of thermoplastic material with continuous fibers, is inserted simultaneously into two adjacent bores 5 (cf. FIG. 1, step 4) for thermoplastic riveting according to the invention, via its two legs 21 and 22. The central joining portion 23 of the staple 20 is flattened against the edge 10b during the heating by the heating panels 30a and 30b.

(11) The schematic views in FIG. 4 show a variant of the last steps of the method of FIG. 1, using a particular cylindrical bore 5 to insert (arrow F3) the strand 6. This bore 5 is created by a holing spike (cf. FIG. 1) the geometry of which is adapted in that it has a conical tapered end shape so as to create a corresponding widened entrance 40 for a countersunk head (step 4). Thanks to this widened entrance 40, the strand 6 becomes easier to insert and its anchorage is reinforced in the way described hereinbelow. After insertion, the strand 6 is cut off to leave an excess end portion overhanging the face 11a. Its other edge is headed using a rivet-heading tool which forms a rivet-heading die 41 in the heating panel 30b (step 4). Through compression and heating using the panels 30a and 30b, the other end of the strand 6 is headed into the shape of a hemispherical upset head 62 (step 7). The widened entrance 40 and the rivet-heading die 41 thus allow optimized anchorage of the strand 6, the excess material occupying the empty space of the recesses 40 and 41, thus creating the widened ends of the strand 6.

(12) The invention is not restricted to the exemplary embodiments described and depicted. Thus, in the heating system, the heating part may be the holding spike rather than the heating panels. Or alternatively, non-holed heating panels may supplement the holed heating panels during the course of the steps of the method.

(13) The cylindrical bores created in the heating panels may have a circular, polygonal or oblong base.

(14) The widened entrances to the bores may also be created by any machining method: milling, routing, turning, etc.

(15) Furthermore, the assembly tie may be is made up of a composite material based on thermoplastic resin reinforced with any known and suitable filler element.