Method for producing a workpiece made from a fiber-reinforced thermoplastic material

Abstract

Method for producing at least one workpiece (1; 18) comprising at least locally a rounded shape and / or an angle and formed from a fiber-reinforced thermoplastic material, wherein the method comprises the following successive steps - at least one step (100; 110) of winding at least one fiber pre-impregnated with a thermoplastic material around a mandrel (M) to form a layered stacking (8; 21) on the mandrel comprising a wound layer of fibers or several wound and superimposed layers of fibers, - at least one step (200; 210) of cutting out the formed layering (8; 21), and - at least one step (300; 310) of removing the cut-out layer layer from the mandrel (M).

Description

Technical field of the invention

[0001] The present invention relates generally to workpieces made from a composite material comprising a thermoplastic, fiber-reinforced material.

[0002] More precisely, the invention relates to a method for manufacturing a workpiece which at least locally comprises a rounded shape and / or an angle and which is formed from a thermoplastic, fiber-reinforced material, such as a molded part used to join at least two elements. State of the art

[0003] The use of a molded part made of composite material, in particular a thermoplastic material reinforced with fibers such as glass or carbon fibers, is particularly advantageous for replacing metal molded parts in areas where weight saving is essential, such as in aviation.

[0004] Certain types of fittings have, at least locally, complex shapes that are rounded and / or include an angle.

[0005] It is known to manufacture these molded parts from sheets formed from a flat stack of layers of fibers bonded together by a thermoplastic material.

[0006] The sheets are deformed and arranged to create a preform. Certain sections of the sheets are curled, folded, or cut and shifted to form the rounded sections and angles of the molded part to be produced.

[0007] However, curling the sheets to produce non-developing, rounded or angular shapes according to such a manufacturing process involves mechanical weaknesses, which greatly impairs the performance of the molded part by reducing its mechanical strength properties.

[0008] Furthermore, the correct arrangement of the material of the sheets of rounded sections and the angles to form the preform remains complex, which limits industrialization. Summary of the invention

[0009] The aim of the invention is therefore to overcome these disadvantages and to provide a simple method for producing a workpiece, such as a molded part, made from a thermoplastic, fiber-reinforced material and comprising non-deploying, complex sections that preserve the mechanical properties of the workpiece.

[0010] Therefore, a method for producing one or more workpieces is proposed which at least locally have a rounded shape and / or an angle and which are formed from a thermoplastic, fiber-reinforced material, characterized in that it comprises the following successive steps: - at least one step of winding at least one fiber pre-impregnated with a thermoplastic material around a mandrel to form a layered structure on the mandrel comprising a wound layer of fibers or several wound and superimposed layers of fibers, - at least one step of cutting out the formed layered structure, - at least one step of removing the cut-out layer from the mandrel.

[0011] In one embodiment, the workpiece to be produced is obtained directly from the cut-out layered material.

[0012] In another embodiment, the manufacturing process comprises one or more preforms of the workpiece to be produced, which are obtained from the cut-out layered structure, and further comprises a step of inserting one or more of the preforms into a mold and overmolding with a thermoplastic material.

[0013] For procedural reasons, the cut-out layered structure or preform may have a slightly different shape than the shape of the final workpiece to be produced, whereby the overmolding step in the mold may make it possible to obtain the desired final shape.

[0014] In one embodiment, the manufacturing process may comprise several winding steps, several cutting steps for the formed layered structures, several steps of removing one or more preforms of the workpiece, which are to be produced from each cut-out layered structure, from the mandrel, wherein the manufacturing process further comprises a step of stacking several obtained preforms on top of each other, wherein the overmolding step is carried out on the stacked preforms.

[0015] In one embodiment, the step of cutting out the layered structure can lead to the production of two identical workpieces during the step of removing them from the mandrel.

[0016] Preferably, the step of wrapping the fiber around the mandrel is controlled by a computer.

[0017] Advantageously, the winding step can be supported by laser heating to keep the thermoplastic material of the pre-impregnated fiber in a liquid state.

[0018] Preferably, the fiber is wrapped around the mandrel to form several angles relative to the axis of the mandrel.

[0019] For example, the material of the fibers wrapped around the mandrel can be selected from: carbon, glass, Kevlar® or a mixture thereof.

[0020] Advantageously, several cut-out layer stacks or several preforms can be joined by a welding step, such as a step of ultrasonic welding.

[0021] Alternatively, several cut-out layered components or multiple preforms can be joined together in a single solidification step through heating. Heating allows the thermoplastic material to melt again. The differently heated cut-out layered components or the differently heated preforms to be arranged are joined together during the cooling of the thermoplastic material.

[0022] The invention also relates to a molded part made of composite material, which is produced by carrying out the manufacturing process described above. Brief character description

[0023] Further objectives, advantages and features will become apparent from the following description, which is given for illustrative purposes only and with reference to the attached drawings, in which: [ Fig. 1] represents a first molded part to be produced, [ Fig. 2] is a flowchart that shows the steps of a manufacturing process for the in Fig. 1 represents the first molded part according to an exemplary embodiment of the invention, [ Fig. 3A], [ Fig. 3B], [ Fig. 3C], [ Fig. 3D] and [ Fig. 3E] schematic perspective views of the in Fig. 1 first molded part shown in different steps of the manufacturing process according to an exemplary embodiment of the manufacturing process of the invention, [ Fig. 4] represents a second molded part to be produced, [ Fig. 5] is a flowchart that shows the steps of a manufacturing process for the in Fig. 4 represents the second molded part according to an exemplary embodiment of the invention, and [ Fig. 6A] and [ Fig. 6B] Schematic perspective views of the in Fig. Figure 4 shows the second molded part in different steps of its manufacture according to an exemplary embodiment of the manufacturing process of the invention. Detailed description of the invention

[0024] Fig. Figure 1 shows a first exemplary embodiment of a workpiece 1 to be manufactured. The workpiece 1 to be manufactured is a T-shaped fitting used to connect two ball joint elements that move relative to each other, and which are intended in particular to be used in the field of aviation.

[0025] Below, the molded part according to the first exemplary embodiment is referred to as the "first molded part".

[0026] The first fitting 1 comprises a body 2. The body 2 comprises a first section 2a, which is also called the cheek, and a second section 2b, which has the shape of a base and includes a fastening zone for the first element to be joined.

[0027] The first section 2a includes a through-hole 3 located near an upper end and designed to accommodate a ball joint. The first section 2a and the second section 2b are monolithic and each extend along substantially perpendicular geometric planes.

[0028] The term “essentially perpendicular” should be understood here to mean that the angle formed between the two geometric planes is enclosed within a range of 60° to 90°.

[0029] The cheek 2a here comprises a first and a second opposing main surface 4 and 5. The two main surfaces 4, 5 are essentially parallel and diverge away from each other in a lower section of the cheek in one direction until they come into contact with the base.

[0030] The first shaped piece 1 shown comprises two complex sections, each formed by a projection. A first projection 6 extends at the junction of the first surface 4 and the base 2b, and a second similar projection extends at the junction between the second surface 5 and the base 2b. These projections 6 provide a wave-like appearance to the body 2 and improve the stiffness of the first shaped piece 1.

[0031] A first exemplary embodiment of the manufacturing process according to the invention, which is designed to produce the first molded part 1 from composite material formed from thermoplastic, fiber-reinforced material, is described with reference to the flowchart in Fig. 2 described.

[0032] As in Fig. As shown in Figure 3A, during step 100, one or more pre-impregnated fibers made of a thermoplastic material are wound around a mandrel M to form a layered structure 8 on the mandrel M, consisting of several layers of wound fibers stacked on top of each other. In one variant, the layered structure 8 can comprise a single layer of wound fibers.

[0033] In the exemplary embodiment shown, a fiber in the form of a band is wound around the mandrel M.

[0034] According to an alternative, several fibers can be wound around the mandrel M simultaneously.

[0035] Each fiber is initially pre-wound onto a head.

[0036] To perform the thread winding, the mandrel M is rotated around its axis X.

[0037] A partial step of the initial winding of the pre-impregnated fibers around the mandrel M allows a first layer to be formed around the mandrel M. This first layer is formed by rotating the mandrel M about its axis X and shifting the heads that carry the fibers parallel to the axis X.

[0038] Subsequently, a series of partial steps of winding the fibers enables the layering 8 to be formed by superimposing the layers one on top of the other around the mandrel M.

[0039] According to an alternative, the layering 8 can be formed from a single layer of wound fibers.

[0040] Advantageously, step 100 of winding the fibers around the mandrel M can be controlled by a computer and thus automated.

[0041] Preferably, each fiber is wound around the mandrel M to advantageously form several angles relative to the axis X of the mandrel M, in order to improve the final mechanical strength properties of the first manufactured component 1. Preferably, the angle varies between 0 and 90°.

[0042] For example, for the same layer of fibers, the angle formed relative to the axis X of the mandrel M may be essentially constant plus or minus 5°, and for each new layer, the angle formed relative to the axis X of the mandrel M for that new layer may differ from the angle of the previous layer, while remaining essentially constant plus or minus 5° during the formation of that new layer.

[0043] The fibers can be, for example, glass fibers, carbon fibers, Kevlar® fibers, or any other suitable material.

[0044] The thermoplastic material is selected, for example, from the group of the following materials: PEEK, PEKK, PPS, PEAK or any other suitable material.

[0045] With regard to the Fig. 3A and Fig. 3B In this first exemplary embodiment, the mandrel M has an outer surface comprising first and second grooves M1 and M2, which are radially opposite and are designed to form first and second grooves 13 and 14 on the layering 8 and the first and second projections 6 of the first molded part 1 to be produced.

[0046] In step 200, the layering 8, which is obtained at the end of step 100 of the thread winding, is cut out.

[0047] The number of cutouts can vary as a function of the number and shape of the preforms that are to be obtained for the production of the desired workpiece.

[0048] As in Fig. As shown in Figure 3B, in the first exemplary embodiment, four cutouts are made in the layered structure 8. The number of cutouts can, of course, vary.

[0049] Subsequently, in step 300, the cut-out sections of the layer layering 8 are removed from the mandrel M to obtain the workpiece to be produced, which is the first molded part in this first illustrated exemplary embodiment.

[0050] The first and second ends 9 and 10 of the layering 8 are removed via two cutouts formed in a plane perpendicular to the axis of the mandrel M and are not used.

[0051] Two other cutouts are formed in two different planes parallel to the axis X of the mandrel M to obtain identical first and second middle sections, forming first and second preforms 11 and 12, which are essentially identical.

[0052] Each of the first and second preforms 11 and 12 includes one of the first and second grooves 13 and 14.

[0053] As in Fig. As can be seen in 3C, the first and second opposing main surfaces are each formed from one of the preforms obtained in this way from the common layering 8 formed in step 100 of the thread winding, and positioned against each other.

[0054] In the with reference to Fig. In the exemplary embodiment shown in 3D, the first and second preforms 11 and 12 are subsequently positioned in a mold 15 to carry out an additional overmolding step 500, also known as injection molding. The overmolding is carried out using a thermoplastic material.

[0055] Preferably, the overmolding is carried out using a thermoplastic material identical to the thermoplastic material of the pre-impregnated fibers used for step 100 of the thread winding around the mandrel M. The thermoplastic material can, for example, be reinforced with fibers.

[0056] In the exemplary embodiment shown, thermoplastic, fiber-reinforced material 16 is added to the first and second preforms 11 and 12 by overmolding in order to join the first and second preforms 11 and 12 and to form the base 2b of the first molded part 1.

[0057] According to an alternative to the overmolding step 500, the first and second preforms 11 and 12 can be joined by a welding step, for example an ultrasonic welding step.

[0058] After the overmolding step, the resulting workpiece 17, which is in Fig. 3E is shown, removed in a step of 600 from the form 15.

[0059] According to embodiments, step 600 of removal can optionally be followed by steps 700 to complete the workpiece 17, for example, steps for machining and / or polishing and / or surface treatment and applying a coating and / or inserting a tenon to obtain the first molded part 1, as in Fig. 1 is shown.

[0060] Fig. Figure 4 shows a second embodiment of a workpiece to be manufactured. The workpiece to be manufactured is a fitting known as a corner fitting, which serves to connect, reinforce and stiffen three planes together, and which is intended in particular for use in the field of aerospace.

[0061] Below, the molded part according to the second embodiment is referred to as the "second molded part".

[0062] The second molded part 18 comprises a body 19. The body 19 comprises a first section 19a, a second section 19b and a third section 19c, which are one-piece and each extend in different geometric planes.

[0063] The first and second sections 19a and 19b form two wings, the connection of these forms a bending line 20 and extends in two essentially perpendicular planes.

[0064] The third section 19c extends in a plane that is substantially perpendicular to the plane of the first section 19a and substantially perpendicular to the plane of the second section 19b, and extends from a first end of the first section 19a to a first end of the second section 19b.

[0065] The term “essentially perpendicular” should be understood here to mean that the angle formed between the pairwise considered geometric planes is enclosed within a range of 60° to 90°.

[0066] The outer surface of each first section 19a, second section 19b and third section 19c forms a connecting zone with one of the three levels of an arrangement in which the second fitting 18 is to be attached.

[0067] A second exemplary embodiment of the manufacturing process according to the invention, which is provided for the simultaneous production of two second molded parts 18, which are made of composite material and which are formed of thermoplastic material reinforced with fibers, is described with reference to the flowchart of Fig. 5 described.

[0068] As in Fig. As shown in Figure 6A, during step 110 one or more pre-impregnated fibers made of a thermoplastic material are wound around a mandrel M to form a layered stacking 21 on the mandrel M, which consists of several layers of fibers that are wound and stacked on top of each other.

[0069] In the exemplary embodiment shown, a fiber in the form of a band is wound around the mandrel M.

[0070] According to an alternative, several fibers can be wound around the mandrel M simultaneously.

[0071] Each fiber is initially pre-wound onto a head.

[0072] To perform the thread winding, the mandrel M is rotated around its axis X.

[0073] A partial step of the initial winding of the pre-impregnated fibers around the mandrel M allows a first layer to be formed around the mandrel M. This first layer is formed by rotating the mandrel M about its axis X and shifting the fibers parallel to the axis X.

[0074] Subsequently, a series of partial steps of winding the fibers enables the layering 21 to be formed by superimposing the layers one on top of the other around the mandrel M.

[0075] According to an alternative, the layering 21 can be formed from a single layer of wound fibers.

[0076] Advantageously, step 110 of winding the fibers around the mandrel M can be controlled by a computer and thus automated.

[0077] Preferably, each fiber is wound around the mandrel M to advantageously form several angles relative to the axis X of the mandrel M, in order to improve the final mechanical strength properties of the manufactured second component 1. Preferably, the angle varies between 0 and 90°.

[0078] For example, for the same layer of fibers, the angle formed relative to the axis X of the mandrel M may be essentially constant plus or minus 5°, and for each new layer, the angle formed relative to the axis X of the mandrel M for that new layer may differ from the angle of the previous layer, while remaining essentially constant plus or minus 5° during the formation of that new layer.

[0079] The fibers can be, for example, glass fibers, carbon fibers, Kevlar® fibers, or any other suitable material.

[0080] With regard to the Fig. 6A and Fig. 6B In this second exemplary embodiment, the mandrel M has a first and a second angular section M3 and M4, which are radially opposite and which extend axially between the two ends of the mandrel M, each being provided to form a bending line of one of the two second molded parts 18 to be produced.

[0081] In step 210, the layering 21, which is obtained at the end of step 110 of the thread winding, is cut out.

[0082] As in Fig. As shown in Figure 6B, in the second embodiment shown, a single cutout is made in the layered structure 21. Of course, the number of cutouts can vary.

[0083] Subsequently, in step 310, the cut-out sections of the layering 21 are removed from the mandrel M to obtain the workpieces to be produced, which are the second molded parts 18 in this second exemplary embodiment shown.

[0084] The cutout is made in a plane that is inclined relative to the axis X of the mandrel M in order to obtain two second, essentially identical shaped pieces 18 from the common layering 21.

[0085] According to embodiments, step 210 of cutting out optional steps 610 of finishing the second molded parts 18 may be followed, for example, steps of machining and / or polishing and / or adding material and / or surface treatment and applying a coating.

[0086] In another embodiment, the manufacturing process can comprise several winding steps 100, 110, each of which involves winding one or more fibers pre-impregnated with a thermoplastic material around the mandrel M. The layered structure 8, 21 formed at the end of each winding step is cut out and removed from the mandrel M to obtain several preforms. Alternatively, the multiple winding steps 100, 110 can be performed on several different mandrels.

[0087] The manufacturing process also includes a step of stacking several preforms on top of each other, which are obtained at the end of different winding steps. The overmolding step 500 is thus carried out on the resulting stack of preforms within mold 15.

[0088] The first and second molded parts 1, 18, which are obtained according to the first and second embodiments, are only possible examples of a workpiece to be produced according to the manufacturing process according to the invention, and other shapes or configurations are possible without deviating from the scope of the invention.

Claims

[1] Method for producing one or more workpieces (1; 18) which at least locally comprise a rounded shape and / or an angle and are formed from a thermoplastic, fiber-reinforced material, characterized by that it comprises the following successive steps: - at least one step (100; 110) of winding at least one fiber pre-impregnated with a thermoplastic material around a mandrel (M) to form a layered stacking (8; 21) on the mandrel comprising a wound layer of fibers or several wound and superimposed layers of fibers, - at least one step (200; 210) of cutting out the formed layering (8; 21), and - at least one step (300; 310) of removing the cut-out layer layer (8; 21) from the mandrel (M). [2] Manufacturing method according to claim 1, wherein the workpiece (18) to be produced is obtained directly from the cut-out layer layer (21). [3] Manufacturing method according to claim 1, comprising one or more preforms (11, 12) of the workpiece (18) to be produced, which are obtained from the cut-out layer layer (21), and further comprising a step (400) of inserting one or more of the preforms (11, 12) into a mold (15) and a step (500) of overmolding with a thermoplastic material. [4] Manufacturing method according to claim 3, comprising several winding steps (100; 110), several cutting steps (200; 210) for the formed layered layers, several steps (300; 310) of removing one or more preforms of the workpiece to be produced from each cut-out layered layer from the mandrel, wherein the manufacturing method further comprises a step of stacking several obtained preforms on top of each other, wherein the overmolding step is carried out on the stacking of preforms. [5] Manufacturing method according to one of the preceding claims, wherein several cut-out layer layers or several preforms can be joined by a welding step, such as an ultrasonic welding step. [6] Manufacturing method according to one of the preceding claims, wherein the step (310) of cutting out the layered layer (21) leads to the production of two identical workpieces (18) during the step (300; 310) of removing from the mandrel (M). [7] Manufacturing method according to one of the preceding claims, wherein the winding step (100; 110) is assisted by laser heating to keep the thermoplastic material of the pre-impregnated fiber in the liquid state. [8] Manufacturing method according to one of the preceding claims, wherein the fiber is wound around the mandrel (M) to form several angles relative to the axis (X) of the mandrel (M). [9] Manufacturing method according to any of the preceding claims, wherein the material of the fibers wound around the mandrel (M) is selected from: carbon, glass, Kevlar® or a mixture thereof. [10] Molded part made of composite material, characterized bythat it is manufactured by carrying out the manufacturing process according to one of the preceding claims.

Images