Fiber-Reinforced Thermoplastic Laminate

Abstract

A fiber-reinforced thermoplastic laminate is disclosed that comprises continuous reinforcing fiber. The laminate is custom designed and fabricated to be molded into a specific article of manufacture. The laminate comprises a plurality of thermoplastic patches that are disjoint and some of which partially overlap.

Claims

1. A method for fabricating a fiber-reinforced thermoplastic laminate, the method comprising: assembling a first thermoplastic patch that is substantially planar onto a second thermoplastic patch that is substantially planar; and consolidating the first thermoplastic patch and the second thermoplastic patch into a fiber-reinforced thermoplastic laminate.

2. The method of claim 1: wherein the first patch comprises parallel reinforcing fibers in a first direction; and wherein the second patch comprises parallel reinforcing fibers in a second direction; and wherein the first direction is different than the second direction.

3. The method of claim 1: wherein the first patch comprises a first shape; and wherein the second patch comprises a second shape; and wherein the first shape is different than the second shape.

4. The method of claim 1 further comprising: cutting the first patch from a sheet of fiber-reinforced thermoplastic; and cutting the second patch from the sheet of fiber-reinforced thermoplastic.

5. A fiber-reinforced thermoplastic laminate comprising: a first layer of patches that comprises: (i) a first thermoplastic patch that is substantially planar, and (ii) a second thermoplastic patch that is substantially planar, wherein the first thermoplastic patch and the second thermoplastic patch are disjoint and do not overlap; and a second layer of patches that comprises: (i) a third thermoplastic patch that is substantially planar, and (ii) a fourth thermoplastic patch that is substantially planar, wherein the third thermoplastic patch and the fourth thermoplastic patch are disjoint and do not overlap; and

6. The method of claim 5: wherein the first patch comprises parallel reinforcing fibers in a first direction; and wherein the second patch comprises parallel reinforcing fibers in a second direction; and wherein the first direction is different than the second direction.

7. The method of claim 5: wherein the first patch comprises a first shape; and wherein the second patch comprises a second shape; and wherein the first shape is different than the second shape.

8. An article of manufacture comprising: a non-planar fiber-reinforced thermoplastic laminate that comprises: (1) a first layer of patches that comprises: (i) a first thermoplastic patch that is substantially planar, and (ii) a second thermoplastic patch that is substantially planar, wherein the first thermoplastic patch and the second thermoplastic patch are disjoint and do not overlap; and (2) a second layer of patches that comprises: (i) a third thermoplastic patch that is substantially planar, and (ii) a fourth thermoplastic patch that is substantially planar, wherein the third thermoplastic patch and the fourth thermoplastic patch are disjoint and do not overlap.

9. The method of claim 8: wherein the first patch comprises parallel reinforcing fibers in a first direction; and wherein the second patch comprises parallel reinforcing fibers in a second direction; and wherein the first direction is different than the second direction.

10. The method of claim 8: wherein the first patch comprises a first shape; and wherein the second patch comprises a second shape; and wherein the first shape is different than the second shape.

11. A method comprising: cutting: (i) a first thermoplastic patch that is substantially planar, and (ii) a second thermoplastic patch that is substantially planar, wherein the second thermoplastic patch lies at least partially on the first thermoplastic patch; and assembling and consolidating the first thermoplastic patch and the second thermoplastic patch into a fiber-reinforced thermoplastic laminate; and thermoforming the fiber-reinforced thermoplastic laminate into an article of manufacture.

12. The method of claim 11: wherein the first patch comprises parallel reinforcing fibers in a first direction; and wherein the second patch comprises parallel reinforcing fibers in a second direction; and wherein the first direction is different than the second direction.

13. The method of claim 12: wherein the first patch comprises a first shape; and wherein the second patch comprises a second shape; and wherein the first shape is different than the second shape.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] FIG. 1 depicts a flowchart of the salient tasks associated with the illustrative embodiment of the present invention.

[0070] FIG. 2a depicts an orthographic top view of cover 200, drawn to scale, as shown.

[0071] FIG. 2b depicts an orthographic front view of cover 200, drawn to scale as shown.

[0072] FIG. 2c depicts an orthographic side view of cover 200, drawn to scale as shown.

[0073] FIG. 2d depicts an isometric perspective drawing of cover 200.

[0074] FIG. 3 depicts a flowchart of the salient tasks associated with task 102—designing the fiber-reinforced thermoplastic laminate from which cover 200 will be fabricated.

[0075] FIG. 4a depicts an orthographic top view of first candidate laminate 400, drawn to scale, as shown.

[0076] FIG. 4b depicts an orthographic front view of first candidate laminate 400, drawn to scale as shown.

[0077] FIG. 5 depicts a schematic composition of the logical layers that compose first candidate laminate 400

[0078] FIG. 6 depicts an orthographic top view of laminate layer 501.

[0079] FIG. 7 depicts an orthographic top view of laminate layer 502, which depicts the shape, location, and orientation of each of the six patches.

[0080] FIG. 8 depicts an orthographic top view of laminate layer 503, which depicts the shape and location of the four segments.

[0081] FIG. 9 depicts an orthographic top view of laminate layer 504, which depicts the shape, location, and orientation of each of the nine patches.

[0082] FIG. 10 depicts an orthographic top view of laminate layer 505.

[0083] FIG. 11 depicts a flowchart of the salient subtasks associated with task 104—fabricating the fiber-reinforced thermoplastic laminate.

[0084] FIG. 12a depicts a flowchart of the orthogonal front view of mold 1200, which is a male mold.

[0085] FIG. 12b depicts a flowchart of the orthogonal side view of mold 1200.

[0086] FIG. 12c depicts a flowchart of the orthogonal side view of mold 1200.

DEFINITIONS

[0087] Article—For the purposes of this specification, the word “article” and its inflected forms is defined to be a synonym of an “article of manufacture.”

[0088] Full Sheet—For the purposes of this specification, a “full sheet” of fiber-reinforced thermoplastic, unreinforced thermoplastic, or fiber reinforcement without thermoplastic is defined as having a footprint equal to or greater than the footprint of the fiber-reinforced thermoplastic laminate.

[0089] Laminate—For the purposes of this specification, the word “laminate” and its inflected forms is defined to be a synonym of “fiber-reinforced thermoplastic laminate.”

[0090] Patch—For the purposes of this specification, a “patch” of fiber-reinforced thermoplastic, unreinforced thermoplastic, or fiber reinforcement without thermoplastic is defined as having a footprint less than the footprint of the fiber-reinforced thermoplastic laminate.

[0091] RTL— For the purposes of this specification, the initialism “RTL” and its inflected forms is defined to be a synonym of “fiber-reinforced thermoplastic laminate.”

DETAILED DESCRIPTION

[0092] FIG. 1 depicts a flowchart of the salient tasks associated with the illustrative embodiment of the present invention.

[0093] At task 101, an engineer with the assistance of a computer-aided design system designs an article of manufacture that is to be fabricated by thermoforming a fiber-reinforced thermoplastic laminate. As part of task 101 the engineer considers: [0094] (i) the desired utility of the article; and [0095] (ii) the desired aesthetics of the article; and [0096] (iii) the desired physical (e.g., structural, thermal, electromagnetic, etc.) attributes of the article; and [0097] (iv) the desired material and production costs to fabricate the article
in order to produce: [0098] (a) a complete specification of the required geometry of the article; and [0099] (b) a complete specification of the physical (e.g., structural, thermal, electromagnetic, etc.) requirements of the article; and [0100] (c) a complete specification of the economic requirements for fabricating the article; and [0101] (d) a complete specification of the post-processing requirements of the article.
In accordance with the illustrative embodiment, the article is the cover for a machine—cover 200. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that fabricate a different article.

[0102] In accordance with the illustrative embodiment, the complete specification of the required geometry of cover is given in FIGS. 2a, 2b, and 2c, which depict orthographic top, front, and side views, respectively, of cover 200. FIG. 2d depicts an isometric perspective drawing of cover 200.

[0103] Cover 200 is 80.0 (Δx) by 80.0 mm (Δy) by 60.0 mm (Δz). The salient features of cover 200 are a concave depression (when viewed from the top) and a depressed shoulder in one quadrant. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that have any required geometry.

[0104] In accordance with the illustrative embodiment, the complete specification of the physical requirements of cover 200 comprises a detailed specification of the structural properties (e.g., tensile strength, compressive strength, stiffness, modulus, etc.) of each portion of cover 200. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that have any physical requirements.

[0105] In accordance with the illustrative embodiment, the complete specification of the post-processing requirements of cover 200 comprises a requirement that the base be die cut from the square laminate from which it is formed, and that the top side of cover 200 be sanded and painted. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that have any post-processing requirements.

[0106] At task 102, the engineer designs a custom fiber-reinforced thermoplastic laminate from which cover 200 will be thermoformed. Task 102 is described in detail in FIG. 3 and the accompanying text.

[0107] At task 103, the mold, post-processing die, and clamping frame for thermoforming the laminate designed in task 102 is designed and fabricated in well-known fashion. In accordance with the illustrative embodiment, the mold is a “male” mold, as shown in FIGS. 12a, 12b, and 12c, but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which a female or a hybrid mold is used.

[0108] At task 104, the fiber-reinforced thermoplastic laminate that is designed in task 102 is fabricated. Task 104 is described in detail in FIG. 11 and the accompanying text.

[0109] At task 105, the article that is designed in task 101 is fabricated by thermoforming the fiber-reinforced thermoplastic laminate that was designed in task 102 and fabricated in task 104. It will be clear to those skilled in the art how to perform task 105.

[0110] At task 106, the article that was thermoformed in task 105 is post processed in accordance with the post-processing requirements to produce the finished article of manufacture. It will be clear to those skilled in the art how to perform task 106.

[0111] FIG. 3 depicts a flowchart of the salient tasks associated with task 102—designing the fiber-reinforced thermoplastic laminate from which cover 200 will be fabricated.

[0112] At task 301, an engineer with a computer-aided design system custom designs a fiber-reinforced thermoplastic laminate that will be thermoformed into cover 200. As part of this task, the engineer considers: [0113] (i) the required geometry of the article in general, and, in particular, how the different portions of the laminate must stretch and be displaced to conform to the contour of the mold; and [0114] (ii) the physical requirements of the article in general, and, in particular, whether the laminate will satisfy the physical requirements of the article after the laminate has been stretched and deformed; and [0115] (iii) the economic requirements of the article; and [0116] (iv) the post-processing requirements of the article
to produce a complete specification of the laminate, which includes, among other things: [0117] (i) a description of the overall dimensions of the laminate; and [0118] (ii) a description of the number of layers that will compose the laminate; and [0119] (iii) a description of whether each layer comprises: [0120] a full sheet of thermoplastic embedded with reinforcing fiber, or [0121] a full sheet of thermoplastic without reinforcing fiber, or [0122] a full sheet of reinforcing fiber without thermoplastic, or [0123] one or more patches of thermoplastic embedded with reinforcing fiber, or [0124] one or more patches of thermoplastic without reinforcing fiber, or [0125] one or more patches of reinforcing fiber without thermoplastic, or [0126] one or more metallic or plastic structural inserts. [0127] (iv) a description of the overall dimensions and relative location of each piece in each layer; and [0128] (v) for each piece that comprises a thermoplastic, a description of which thermoplastic(s) will compose that layer; and [0129] (vi) for each piece that comprises reinforcing fiber, a description of the chemical makeup of the reinforcing fiber (e.g., carbon, glass, aramid, hemp, etc.); and [0130] (vii) for each piece that comprises reinforcing fiber, a description of whether the reinforcing fiber are continuous or chopped; and [0131] (viii) for each piece that comprises reinforcing fiber, a description of the number or density of the fibers; and [0132] (ix) for each piece that comprises continuous reinforcing fiber, a description of whether the reinforcing fiber are unidirectional or multidirectional; and [0133] (x) for each piece that comprises continuous reinforcing fiber, a description of the angular orientation of the fibers; and [0134] (xi) for each piece that comprises continuous reinforcing fiber, a description of whether any continuous fibers are to be severed; and if so where the cuts should be; and [0135] (xii) for each metallic or plastic structural insert, a description of its size, shape, location, and material composition.

[0136] After considering these factors, the engineer produces a first design for the laminate—first candidate laminate 400. FIGS. 4a and 4b depict orthographic top and front views of first candidate laminate 400, and FIG. 5 depicts a schematic composition of the logical layers that compose first candidate laminate 400. With regard to a “layer,” the elements composing a layer are deposited during the creation of the layup after all of the elements of the “lower” layer are deposited and before any of the elements of the “upper” layer are deposited.

[0137] The overall dimensions of first candidate laminate 400 are 80.0 (Δx) by 80.0 mm (Δy) and has a thickness of 0.3 mm (Δz). It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention of any dimension.

[0138] First candidate laminate 400 comprises five layers: [0139] (i) laminate layer 501, and [0140] (ii) laminate layer 501, and [0141] (iii) laminate layer 503, and [0142] (iv) laminate layer 504, and [0143] (v) laminate layer 505.

[0144] Laminate Layer 501—The principal purpose of laminate layer 501 is to provide bulk thermoplastic adjacent to laminate layer 501, and, therefore, laminate layer 501 is devoid of reinforcing fiber. FIG. 6 depicts an orthographic top view of laminate layer 501. Laminate layer 501 is 80.0 mm (Δx) by 80.0 mm (Δy) by 0.05 mm (Δz). Laminate layer 501 is composed entirely of polyethyletherketone (PEEK). In the process of forming the layup prior to consolidation, layer 501 is deposited first. It will be clear to those skilled in the art how to make laminate layer 501.

[0145] Laminate Layer 502—The principal purpose of laminate layer 502 is to provide radial tensile strength to cover 200. Because the principal purpose of laminate layer 502 is structural, it comprises six patches of thermoplastic that are each embedded with unidirectional continuous reinforcing fiber. FIG. 7 depicts an orthographic top view of laminate layer 502, which depicts the shape, location, and orientation of each of the six patches. Each patch is 0.1 mm thick (Δz) comprises uni-directional continuous carbon-fiber reinforcement that is wetted with, and embedded in, polyethyletherketone (PEEK). In the process of forming the layup, the six patches composing laminate layer 502 are deposited after and onto laminate layer 501. It will be clear to those skilled in the art how to make and use laminate layer 502.

[0146] Laminate Layer 503—The principal purpose of laminate layer 503 is to provide rigidity and puncture resistance to portions of cover 200. Because the principal purpose of laminate layer 503 is structural, it comprises four segments of a metallic ring. FIG. 8 depicts an orthographic top view of laminate layer 503, which depicts the shape and location of the four segments. Each ring segment is made of 304 stainless steel and is 0.1 mm thick (Δz). In the process of forming the layup, the two ring segments are deposited after and onto the six patches of laminate layer 502. It will be clear to those skilled in the art how to make laminate layer 501.

[0147] Laminate Layer 504—The principal purpose of laminate layer 504 is to provide circumferential tensile strength around the base of cover 200 and structural reinforcement in the center of cover 200. Because the principal purpose of laminate layer 504 is structural, it comprises nine patches of thermoplastic that are each embedded with unidirectional continuous reinforcing fiber. FIG. 9 depicts an orthographic top view of laminate layer 504, which depicts the shape, location, and orientation of each of the nine patches. Six patches are rectangular in shape, as shown in FIG. 8, and each comprises uni-directional continuous carbon-fiber reinforcement that is wetted with, and embedded in, polyethyletherketone (PEEK). One patch is circular in shape, as shown in FIG. 8, and comprises bi-directional continuous carbon-fiber reinforcement that is wetted with, and embedded in, polyethyletherketone (PEEK). All nine patches are 0.1 mm thick (Δz). In the process of forming the layup, the nine patches composing laminate layer 504 are deposited after and onto laminate layer 503, but as a practical matter the nine patches composing laminate layer 504 will rest at the same elevation as the two ring segments of laminate layer 503, all of which will rest on the six patches of laminate layer 502. It will be clear to those skilled in the art how to make and use laminate layer 504.

[0148] Laminate Layer 505—The principal purpose of laminate layer 505 is to provide bulk thermoplastic adjacent to laminate layer 504, and, therefore, laminate layer 505 is devoid of reinforcing fiber. FIG. 10 depicts an orthographic top view of laminate layer 505. Laminate layer 505 is 80.0 (Δx) by 80.0 mm (Δy) by 0.05 mm (Δz). Laminate layer 505 is composed entirely of polyethyletherketone (PEEK). In the process of forming the layup prior to consolidation, layer 505 is deposited after and onto laminate layer 504. It will be clear to those skilled in the art how to make laminate layer 505.

[0149] At task 302, the engineer determines if the article can be thermoformed from first candidate laminate 400 and if the resulting article will satisfy the required geometry of cover 200.

[0150] The process of thermoforming attempts to deform first candidate laminate 400—which is substantially planar—into cover 200—which is non-planar—using a vacuum and mold 1200, as shown in FIGS. 12a, 12b, and 12c. The process of deforming a substantially planar laminate into a non-planar article involves applying forces that cause portions of the laminate to stretch and be laterally displaced. The geometry of the article dictates the geometry of the molds, and the geometry of the molds dictates the location, direction, and magnitude of each of these forces.

[0151] In accordance with the illustrative embodiment, the engineer determines that the thermoforming of candidate laminate 400 on mold 1200 will result in an article that satisfies the geometric requirements of cover 200, and, therefore, control passes to task 303. In the counterfactual case where the thermoforming of candidate laminate 400 on mold 1200 will not result in an article that satisfies the geometric requirements of cover 200, control returns to task 301 where the first candidate laminate 400 will be redesigned. It will be clear to those skilled in the art how to perform task 302 on a candidate laminate.

[0152] At task 303, the engineer next determines if the article thermoformed from the second candidate laminate 900 will satisfy the physical requirements of cover 200, as specified in task 101. In accordance with the illustrative embodiment, the engineer accomplishes this by performing finite element analysis on a model of the laminate after it has been molded into the article considering which areas have fiber and which do not.

[0153] In accordance with the illustrative embodiment, the engineer determines that the thermoforming of candidate laminate 400 on mold 1200 will result in an article that satisfies the physical requirements of cover 200, and, therefore, control passes to task 304. In the counterfactual case where the thermoforming of candidate laminate 400 on mold 1200 will not result in an article that satisfies the physical requirements of cover 200, control returns to task 301 where the first candidate laminate 400 will be redesigned. It will be clear to those skilled in the art how to perform task 303 on a candidate laminate.

[0154] At task 304, the engineer determines if the article thermoformed from third candidate laminate 1500 will satisfy the economic requirements of cover 200, as specified in task 101. In accordance with the illustrative embodiment, the engineer determines that the thermoforming of candidate laminate 400 on mold 1200 will result in an article that satisfies the economic requirements of cover 200, and, therefore, control passes to task 103. In the counterfactual case where the thermoforming of candidate laminate 400 on mold 1200 will not result in an article that satisfies the economic requirements of cover 200, control returns to task 301 where the first candidate laminate 400 will be redesigned. It will be clear to those skilled in the art how to perform task 304 on a candidate laminate.

[0155] FIG. 11 depicts a flowchart of the salient subtasks associated with task 104—fabricating the fiber-reinforced thermoplastic laminate.

[0156] At task 1101, an 80.0 mm by 80.0 mm piece of 0.05 mm of unreinforced thermoplastic (i.e., laminate layer 501) is cut in well-known fashion, and deposited by robot. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which the thermoplastic is cut with a laser, knife, high-pressure waterjet, hot wire, or electric arc.

[0157] At task 1102, the six patches of fiber-reinforced thermoplastic (i.e., laminate layer 502) are cut in well-known fashion, deposited by robot onto the thermoplastic composing laminate layer 501 at the location and orientation shown in FIG. 7, and tacked in place to inhibit movement by bulk heating, spot welding, or induction heating in well-known fashion.

[0158] At task 1103, the two stainless steel ring segments (i.e., laminate layer 503) are deposited by robot onto the patches composing laminate layer 502 at the location and orientation shown in FIG. 8.

[0159] At task 1104, the six rectangular patches of fiber-reinforced thermoplastic (i.e., a portion of laminate layer 504) are cut in well-known fashion, deposited by robot onto the thermoplastic composing laminate layer 503 at the location and orientation shown in FIG. 9, and tacked in place to inhibit movement by bulk heating, spot welding, or induction heating in well-known fashion. Also, as part of task 1104, the one circular piece of fiber-reinforced thermoplastic (i.e., the remaining portion of laminate layer 504) is cut in well-known fashion, deposited onto the thermoplastic patch composing laminate layer 502 at the location and orientation shown in FIG. 9, and tacked in position to inhibit its movement.

[0160] At task 1105, an 80.0 mm by 80.0 mm piece of 0.05 mm of unreinforced thermoplastic (i.e., laminate layer 505) is cut in well-known fashion, heated until it is tacky, and deposited by robot.

[0161] At task 1106, a two-dimensional registration mark is added to two opposite corners of the laminate composing laminate layer 505, with an ink-jet printer, silk screen, or laser.

[0162] At task 1107, the layup assembled in tasks 1101 through 1105 is heated and pressed, in well-known form, into a fiber-reinforced thermoplastic laminate in preparation for task 105.

[0163] After reading this specification, it will be clear to those skilled in the art how to make and use alternative embodiments of the present invention that comprise: [0164] (i) a laminate of any dimensions; and [0165] (ii) a laminate that comprises any number of layers; and [0166] (iii) a laminate in which each layer comprises: [0167] thermoplastic embedded with reinforcing fiber, or [0168] thermoplastic without reinforcing fiber, or [0169] reinforcing fiber without thermoplastic, or [0170] any number of patches, or [0171] any number of metal or plastic reinforcing and [0172] (iv) a laminate in which each layer has any dimensions; and [0173] (v) a laminate in which each layer that comprises thermoplastic comprises any thermoplastic(s); and [0174] (vi) a laminate in which each layer that comprises reinforcing fiber comprises any type of fiber (e.g., carbon, glass, aramid, hemp, etc.); and [0175] (vii) a laminate in which each layer that comprises reinforcing fiber comprises continuous or chopped fiber; and [0176] (viii) a laminate in which each layer that comprises reinforcing fiber comprises any number or density of fibers; and [0177] (ix) a laminate in which each layer that comprises continuous reinforcing fiber comprises unidirectional or multidirectional weaves, braids, tows, etc.; and [0178] (x) a laminate in which each layer that comprises continuous reinforcing fiber, comprises continuous fibers at any angular orientation; and [0179] (xi) a laminate that comprises any number or type metallic or thermoplastic inserts or reinforcements; and [0180] (xiii) a laminate that comprises any number or size of thermoplastic patches.

[0181] In accordance with the illustrative embodiment, the candidate layers composed polyethyletherketone (PEEK), but it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention that are composed of any thermoplastic (e.g., polyaryletherketone (PAEK), polyetherketoneketone (PEKK), polyetheretherketoneketone (PEEKK), polyetherketoneetherketoneketone (PEKEKK), polyamide (PA), polybutylene terephthalate (PBT), poly(p-phenylene sulfide) (PPS), etc. When the thermoplastic comprises a blend of an amorphous polymer with a semi-crystalline polymer, the semi-crystalline polymer can one of the aforementioned materials and the amorphous polymer can be a polyarylsulfone, such as polysulfone (PSU), polyethersulfone (PESU), polyphenylsulfone (PPSU), polyethersulfone (PES), or polyetherimide (PEI). In some additional embodiments, the amorphous polymer can be, for example and without limitation, polyphenylene oxides (PPOs), acrylonitrile butadiene styrene (ABS), methyl methacrylate acrylonitrile butadiene styrene copolymer (ABSi), polystyrene (PS), or polycarbonate (PC).