How to add segments of fiber-reinforced thermoplastic filament to a curve

Abstract

A method for adding segments of a fiber-reinforced thermoplastic filament 111 in additive manufacturing. Adding filament segments involves three processes: (1) determining where the filament segments should be added, (2) dispensing each filament segment at the desired location, and (3) packing each filament segment to remove adhesions and voids. Packing of the filament segments is performed by steering an actuation wheel along the filament. In the illustrated embodiment, the actuation wheel is steered about a yaw axis 313 offset from an actuation wheel axis 312 by a distance s (a positive real number).

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This application relates generally to additive manufacturing processes, and more particularly to additive manufacturing processes that utilize segments of fiber reinforced thermoplastic filaments as elemental units of manufacture. [Background technology]

[0002] It is well known in the art of additive manufacturing that just as a building can be constructed by adding bricks, one after the other, in specific locations and in a specific order, a product can be assembled by adding segments of fiber-reinforced thermoplastic filaments, one after the other, in specific locations and in a specific order, where the segments of filament are long, thin, and resemble moist spaghetti when heated to a temperature near a first temperature and dry spaghetti when cooled below a second temperature.

[0003] Adding a segment of filament consists of three tasks: (1) Determining where each segment of filament should be added (2) providing each segment of the filament at a desired location; (3) Packing each segment of the filament to remove adhesions and voids. Each of these will be considered in turn.

[0004] The task of determining where each segment of filament should be placed is performed by an engineer, a CAD design system, or both. This task can be performed before the first filament is added, but can also be performed in real time during production to compensate for any differences between where the filament segment is actually added and where it should have been added. The longitudinal location of the filament segment to be added shall be referred to as the "target path."

[0005] The target route is: (i) One or more straight sections; (ii) one or more plane curves, (iii) one or more non-planar curves; (iv) one or more combinations of i, ii, and iii Includes.

[0006] Since the filament segments cannot resist gravity and the buoyancy of the air, the filament segments must be provided in whole or in part on a surface of a support structure. Short segments of the filament can be cantilevered or suspended, but the substantial location of the segment must be directly braced. The support structure for the filament segments can be, but is not limited to: (i) Building materials, (ii) a mold; (iii) a mandrel; (iv) Shelf location, (v) one or more additional segments of a filament; (vi) one or more combinations of i, ii, iii, v, and vi Includes.

[0007] Because the target path represents the location where each segment of the filament should be added, the target locations will be near but not at the surface of the support structure. In many cases, the target path will follow the contour of the surface of the adjacent support structure.

[0008] The step of delivering a segment of filament to a desired location includes defining a length of the segment of filament such that the longitudinal axis of the segment is precisely aligned with the intended path.

[0009] The step of packing the filament segment includes forcing the filament into a support structure; (i) adhesion / sticking of the filament to the supporting structure; and (ii) Removal of air pockets (e.g., voids) We guarantee this. Typically, the process of packing a segment of filament involves steering an actuator wheel along the length of the filament, similar to winding laminate or plywood.

[0010] Generally, the success of a filament segment addition manufacturing operation depends on the ability of the system to add each filament segment precisely along a desired path. Unfortunately, there are some things that preparation cannot do. Summary of the Invention [Problem to be solved by the invention]

[0011] Some embodiments of the present invention allow for the addition of filament segments to a support structure without the necessary costs and drawbacks of the prior art, and in particular, some embodiments of the present invention allow for the addition of filament segments to a support structure with greater spatial precision than the prior art.

[0012] In some forms of the prior art, a task of dispensing a segment of filament finishes dispensing the segment before the loading of the segment begins. In other words, a segment of filament is dispensed along a target path, and the segment is loaded after all of the filament has been dispensed. This is disadvantageous for a variety of reasons.

[0013] In some alternative forms of the prior art, and according to the form shown, the step of dispensing is carried out simultaneously with the task of stuffing. To understand this, consider four adjacent portions of a segment of a filament: (1) The first part of the filament segment to be provided and stuffed (2) a second portion of the filament adjacent to and packed into the first portion; (3) a third portion of the filament adjacent to the second portion and being packed; (4) a second portion of the filament adjacent to the third portion and intended to be packed after the third portion is packed; Please take the following into consideration.

[0014] With this background, the inventors of the present invention have discovered that when the target path is curved (both planar and non-planar), segments of the filament are added outside of the target path instead of along the target path (e.g., as shown in FIG. 5, the position of the filament 111 does not coincide with the target path 2065).

[0015] To understand the problem, one must understand how the second portion is introduced into the target path of delivery. In the prior art and in the illustrated embodiment, the second portion is not introduced directly into the target path. There is no machine or mechanism that contacts the second portion.

[0016] Instead, the second portion is indirectly guided between the first and third portions by virtue of its position. In other words, unless movement is restricted, the second portion will be positioned straight between the first and third portions by virtue of the tension between the first and third portions.

[0017] While being packed, the position of the first part is fixed, while the position of the third part is moved laterally in an attempt to bring the second part onto the target path. To achieve this on a curve, the third part is moved to the outside of the curve on the tangent of the curve. Then, while the second part is packed onto the target path, the position of the fourth part is moved laterally in an attempt to bring the third part onto the target path.

[0018] However, in reality, the inventors have found that the working wheel is (i) stuffing a first portion of a filament segment; and (ii) clamping the second portion while the second portion is outside the target path such that the second portion is not directed into the target path; I discovered that.

[0019] This problem can be improved by using a smaller diameter working wheel, but the problem is not completely solved and there are disadvantages to using a smaller working wheel.

[0020] Another measure is to change the way the wheel is steered along the filament. In the prior art and in the illustrated embodiment, the wheel is steered along the filament so that the yaw axis of the wheel intersects and exceeds the target path. However, in the prior art and in the illustrated embodiment, different lines are chosen for the yaw axis of the wheel. These lines are defined in part with respect to a line about which the wheel is substantially symmetric, i.e., the pitch axis of the wheel.

[0021] In the prior art, a line intersecting the pitch axis of the actuation wheel is selected as the yaw axis of the actuation wheel, whereas according to the embodiment shown, a line offset from the pitch axis of the actuation wheel is selected as the yaw axis of the actuation wheel.

[0022] The offset amount is (i) diameter of working wheel, (ii) the cross-sectional dimensions of the filament; (iii) the degree to which the filaments are compressed when packed; (iv) the curvature of the target path relative to the curvature of the working wheel; This is due to several factors, including:

[0023] Furthermore, the amount of offset may vary at different locations along the target path because the curvature of the target path varies at different locations along the target path, and therefore the amount of offset, and the position of the yaw axis of the actuating wheel relative to the pitch axis of the actuating wheel, are dynamically adjusted as the actuating wheel advances along the target path. [Means for solving the problem]

[0024] The illustrated embodiment includes providing a filament on a surface of a support structure along a target path, and packing the filament onto a support structure having an actuator wheel, the actuator wheel having a pitch axis about which the actuator wheel is substantially symmetrical, and a circumferential surface having (ii-a) a nip line segment such that the circumferential surface applies a maximum radial force on a first length of the filament, and (ii-b) a pinch line segment such that the actuator wheel first pinches a second length of the filament between the circumferential surface and the support structure, the pinch line segment being parallel to the pitch axis. a yaw axis, the yaw axis (iii-a) being perpendicular to the pitch axis, (iii-b) having an offset s from the pitch axis that is a positive non-zero real number, and (iii-c) intersecting the pinch line segment; and a roll axis intersecting the pitch axis and the yaw axis and perpendicular to the pitch axis and the yaw axis, wherein progression of the working wheel comprises movement of the working wheel such that the yaw axis intersects the target path and is forward along the target path. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic diagram of the salient components of an additive manufacturing system 100 in accordance with an illustrative embodiment of the present invention. [Figure 2A] FIG. 1 is an orthographic top view of a support structure 106 according to an illustrative embodiment of the present invention. [Figure 2B] FIG. 1 is an orthographic front view of a support structure 106 according to an illustrative embodiment of the present invention. [Figure 2C] FIG. 1 is an orthographic side view of a support structure 106 according to an illustrative embodiment of the present invention. [Figure 3A] FIG. 1 is an orthographic side view of a stuffing tool 108 according to an illustrative embodiment of the present invention. [Figure 3B]FIG. 1 is an orthographic front view of a stuffing tool 108 according to an illustrative embodiment of the present invention. [Figure 3C] FIG. 1 is an orthographic top view of a stuffing tool 108 according to an illustrative embodiment of the present invention. [Figure 4] FIG. 2 is an orthographic top view of the stuffing tool 108 along cross section AA-AA, showing the state of the filament 111 and the straight target path. [Diagram 5] FIG. 1 is a top view of the relationship of the support structure 106, the target path 206, and the filament 111 after the filament 111 has been packed by the actuator wheel 305 and steered using the nip axis 311 as the yaw axis, as in the prior art. [Figure 6] FIG. 1 is a top view of the relationship of the support structure 106, the target path 206, and the filament 111 after the filament 111 has been packed by the actuation wheel 305 and steered using the pinch axis 313 as the yaw axis, as in the illustrated configuration. [Figure 7] FIG. 13 shows an orthographic front view of the stuffing tool 108 along cross section AA-AA at the state of the filament 111 and the recessed target path. [Figure 8] FIG. 13 shows an orthographic front view of the stuffing tool 108 along cross section AA-AA at the state of the filament 111 and the expanded target path. [Figure 9] FIG. 13 shows a flow chart of the operation of the illustrated embodiment. [Figure 10] FIG. 9 shows a flow chart detailing step 904, i.e., stuffing the filament 111 onto the support structure 106 having the stuffing tool 108 by steering the actuating wheel 305 along the filament 111. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] 1 shows a schematic of the salient components of an additive manufacturing system 100 in accordance with an illustrative embodiment of the present invention. The additive manufacturing system 100 includes a platform 101, a robotic fixture 102, a robotic arm 103, a build plate support 104, a build plate 105, a support structure 106, a dispensing head 107, a stuffing tool 108, a controller 109, a filament reel 110, a filament 111, and a build volume 112. The purpose of the manufacturing system 100 is to produce products by successively dispensing finite lengths of filament on top of each other.

[0027] Platform 101 is a rigid structure that ensures that the relative spatial relationships between robot mount 102, robot arm 103, delivery head 107 and stuffing tool 108 are known and maintained with respect to build plate support 104, build plate 105 and support structure 106. It will be clear to one of ordinary skill in the art how to make and use platform 101.

[0028] The robot mount 102 is a rigid and stable support for the robot arm 103. It will be clear to one of ordinary skill in the art how to make and use the robot mount 102.

[0029] The robot arm 103 comprises a six-axis mechanical arm under the control of the controller 109. A non-limiting example of the robot arm 103 is an IRB4600 robot provided by ABB. The robot arm 103 can dispense segments of fiber reinforced thermoplastic filament from any three-dimensional coordinate to any other three-dimensional coordinate in the build volume 112 using the dispense head 107 at any approach angle. The robot arm 103 can: i.+X direction ii. -X direction iii. +Y direction iv. -Y direction v. +Z direction vi. -Z direction vii. In one or more combinations of i, ii, iii, v, and vi, the packing tool 108 can be moved while rotating the approach angle of the packing tool 108 around any line, any planar curve, and any non-planar curve within the build volume 112.

[0030] The build plate support 104 is a rigid and stable support for the build plate 105 and the support structure 106. The build plate support 104 includes a stepper motor that can rotate the build plate 105 (and thus the support structure 106) about an axis perpendicular to the XY plane under the control of a controller 109. It will be clear to one of ordinary skill in the art how to make and use the build plate support 104.

[0031] Build plate 105 is a rigid support to which support structure 106 is rigidly attached such that it cannot move or rotate independently of build plate 105. It will be clear to one of ordinary skill in the art how to make and use build plate 105.

[0032] The support structure 106 comprises finite lengths of filaments that are delivered and packed into the configuration shown in Figures 2A, 2B, and 2C.

[0033] The dispensing head 107 includes hardware for (i) dispensing a finite length of filament 111 onto the support structure 106 along a target path 206 (as shown in FIG. 2A ) and (ii) stuffing the filament into the support structure 106 using a stuffing tool 108, which is a subassembly of the dispensing head 107. The dispensing head 107 is described in detail in U.S. Patent No. 10,076,870, entitled “Filament Guide,” which issued on September 18, 2018 (Attorney File 3019-142us1), which is incorporated by reference for purposes of describing the dispensing head 107. Further incidental detail regarding the dispensing head 107 is provided in U.S. Patent No. 10,076,870, entitled “Filament Guide,” which issued on September 18, 2018 (Attorney File 3019-142us1), which is incorporated by reference for purposes of describing the dispensing head 107. (i) U.S. Patent No. 10,195,786, issued on February 5, 2019 (Attorney File No. 3019-115us1), for an invention entitled “Heater Filament in a 3D Printing System”; and (ii) U.S. Patent No. 10,046,511, issued on August 14, 2018 for an invention entitled “Reducing Torsion Force on Fiber-Reinforced Thermoplastic Filaments” (Attorney File 3019-143us1); and (iii) as described in pending U.S. patent application Ser. No. 15 / 854,676, filed Dec. 26, 2017, entitled “Fiber Reinforced Thermoplastic Filament Curve Dispensing,” (Attorney Docket No. 3019-157us1), all of which are incorporated by reference, and from reading these disclosures and the incorporated documents, it will be apparent to one of ordinary skill in the art how to make and use alternative embodiments of the present invention that use a combination dispensing head / stuffing wheel.

[0034] The controller 109 contains the necessary software and hardware to instruct the build volume 112, the robotic arm 103, the delivery head 107, and the build plate support 104 to manufacture a product. It will be clear to one of ordinary skill in the art how to make and use the controller 109.

[0035] Filament reel 110 comprises an annular reel that stores 1000 meters of filament 111 and supplies the filament to dispensing head 107. It will be clear to one of ordinary skill in the art how to make and use filament reel 110.

[0036] Filament 111 has a reinforcing fiber traction member substantially parallel to the length of the filament. In the illustrated form, filament 111 has a cylindrical traction preg of continuous 12K carbon fiber impregnated with a thermoplastic resin. Filament 111 has a circular cross section and a diameter of 200 micrometers.

[0037] In the form shown, filament 111 comprises continuous carbon fiber, however, it will be apparent to one of ordinary skill in the art in view of the disclosure herein how to make and use alternative embodiments of the present invention in which filament 111 has a different composition.

[0038] It will be apparent to one of ordinary skill in the art, in view of the disclosure herein, how to make and use alternative embodiments of the present invention in which the filament 111 has a different number of fibers (e.g., 1K, 3K, 6K, 24K, etc.) It will be apparent to one of ordinary skill in the art, in view of the disclosure herein, how to make and use alternative embodiments of the present invention in which the filament 111 has fibers of different materials (e.g., fiberglass, aramid, carbon nanotubes, etc.).

[0039] In the illustrated embodiment, the thermoplastic resin is generally a semi-crystalline polymer, specifically a polyaryletherketone (PAEK), also known as polyetherketone (PEK). In alternative embodiments of the present invention, the semi-crystalline material may be a polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetheretherketoneketone (PEEKK), or polyetherketoneetherketoneketone (PEKEKK). One of ordinary skill in the art would recognize based on the disclosure herein that the disclosed annealing process generally involves elevating the temperature of the semi-crystalline polymer above the glass transition temperature, Tg.

[0040] In an alternative embodiment of the present invention, the semi-crystalline polymer is not a polyaryletherketone (PAEK) but another semi-crystalline thermoplastic (e.g., polyamide (PA), polybutylene terephthalate (PBT), poly(p-phenylene sulfide (PPS), etc.)) or a blend of semi-crystalline and amorphous polymers.

[0041] The filament is an amorphous polymer blended with a semi-crystalline polymer, where the semi-crystalline polymer can be one of the materials described above, 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). Based on the disclosure herein, one of ordinary skill in the art would understand that in blending an amorphous polymer with a semi-crystalline polymer, the disclosed annealing process generally includes a temperature below, and in some cases just below, the glass transition temperature of the semi-crystalline polymer.

[0042] The filaments may be a blend of amorphous polymer with semi-crystalline polymer, with the weight ratio of the semi-crystalline material to the amorphous material ranging from about 50:50 to about 95:5, inclusive, or from about 50:50 to about 90:10, inclusive. Preferably, in the blend, the weight ratio of the semi-crystalline material to the amorphous material may range from about 50:50 to about 95:5, inclusive, or from about 60:40 to about 80:20, inclusive. These ratios selected for any particular application may vary as a function of the materials used and the properties desired for the product.

[0043] In some alternative embodiments of the present invention, the filament is metallic. For example, and without limitation, the filament can be stainless steel, Inconel (nickel / chrome), titanium, aluminum, cobalt chrome, copper, bronze, iron, rare earth metals (e.g., platinum, gold, silver, etc.).

[0044] The build volume 112 is a region of three-dimensional space into which the robotic arm 103 can deliver and pack the filament 111. The support structure 106 resides entirely within the build volume 112.

[0045] 2A, 2B and 2C are orthographic front, side and top views of support structure 106 according to an illustrative embodiment of the present invention.

[0046] In the embodiment shown, the support structure 106 has a rectangular footprint, measuring 100 millimeters wide (e.g., in the Δx direction) and 50 millimeters deep (e.g., in the Δy direction). The bottom surface of the support structure 106 (e.g., the surface adjacent to the build plate 105) is planar, adjacent to the build plate 105, and parallel to the build plate 105. The top surface of the support structure 106 is non-planar and continuous (including non-continuous portions) and is represented by the following equation:

number

[0047] Support structure 106 has a rectangular ground area, however, it will be apparent to one of ordinary skill in the art after reading this disclosure to construct and use alternative embodiments of the support structure pairs having different ground areas.

[0048] Support structure 106 has a footprint of 100 mm by 50 mm, although it will be apparent to one of ordinary skill in the art after reading this disclosure to construct and use alternative embodiments of any size.

[0049] Although the support structure 106 has a bottom surface that is planar, it will be apparent to one of ordinary skill in the art in view of this disclosure to construct and use alternative embodiments in which the bottom surface may have any configuration (e.g., planar, non-planar, irregular, concave, convex, hemispherical, etc.).

[0050] Although support structure 106 has a continuous bottom surface, it will be apparent to one of ordinary skill in the art, after reading this disclosure, how to construct and use alternative embodiments in which the bottom surface has one or more discontinuous features.

[0051] The support structure 106 has a bottom surface adjacent to the build plate 105, although it will be apparent to one of ordinary skill in the art in view of this disclosure how to construct and use alternative embodiments in which the bottom surface does not correspond to the build plate 105.

[0052] Although support structure 106 has a non-planar top surface, it will be apparent to one of ordinary skill in the art, given this disclosure, to construct and use alternative embodiments having top surfaces of any shape (e.g., planar, irregular, concave, convex, hemispherical, etc.).

[0053] Although support structure 106 has a continuous top surface, it will be apparent to one of ordinary skill in the art after reading this disclosure how to make and use alternative embodiments in which the top surface has one or more discontinuous features.

[0054] In the embodiment shown, a length of filament is dispensed and packed onto the top surface of support structure 106. In particular, the filament is dispensed onto support structure 106 such that the longitudinal axis of the filament precisely matches the target path 206 non-planar spatial curve. The filament has a circular cross-section with a diameter of 200 micrometers, and the target path 206 is parametrized by the following function vector:

number

number

number

number

[0055] Although the target path 206 is depicted as a continuous non-planar curve, it will be apparent to one of ordinary skill in the art, given this disclosure, to create and use alternative embodiments of the target path (e.g., straight lines, planar curves, non-planar curves, etc.).

[0056] Although target path 206 is illustrated as having no discontinuities, it will be apparent to one of ordinary skill in the art after reading this disclosure how to make and use alternative embodiments in which the target path has one or more discontinuities.

[0057] 3A, 3B and 3C are orthographic front, side and top views of stuffing tool 108 in accordance with an illustrative embodiment of the present invention. Stuffing tool 108 includes a tool shank 301, a working wheel bracket 302, a working wheel axel 303, a working wheel bushing 304 and a working wheel 305. Working wheel 305 is substantially symmetrical about a working wheel axis 312.

[0058] In the embodiment shown, the tool shank 301, wheel bracket 302, wheel axel 303, wheel bushing 304, and wheel 305 are each made from stainless steel, however, it will be apparent to one of ordinary skill in the art after reading this disclosure how to make and use alternate embodiments in which all of the components are made from different materials.

[0059] In the embodiment shown, the angular orientation of the actuating wheel 305 changes with respect to the coordinate system of the additive manufacturing system 100 as it packs the filament 111. In the embodiment shown, the angular orientation of the actuating wheel 305 is represented by the following orthogonal axes: (i) pitch axis, (ii) yaw axis, (iii) Roll axis

[0060] In the embodiment shown, the commonly used and customary correspondences to the roll, pitch, and yaw axes used for an aircraft are not applied to the actuation wheel 305 because the similarities when applied to the actuation wheel 305 are not perfect and could lead to confusion.

[0061] In the embodiment shown, the pitch axis of the working wheel 305 is defined to be the working wheel axis 312 about which it is substantially symmetrical.

[0062] In the embodiment shown, the roll axis of the actuation wheel 305 is generally parallel to the direction of movement of the actuation wheel 305 and is therefore defined to be the roll axis 314 (as shown in FIGS. 3A and 3B ). In the embodiment shown, the roll axis 314 intersects the actuation wheel axis 312 and is defined as horizontal (e.g., perpendicular to the z-axis) such that the actuation wheel 305 does not tilt or tilt as it rotates, unlike an aircraft.

[0063] In the prior art, as shown in Figures 3A, 3B, 3C and 4 and described below, the yaw axis of the actuating wheel 305 is the nip axis 311. In contrast, in the illustrated embodiment, as shown in Figures 3A, 3B, 3C and 4 and described below, the yaw axis of the actuating wheel 305 is the pinch axis 313.

[0064] FIG. 4 is an orthographic front view of the stuffing tool 108 along cross section AA-AA on the condition of the filament 111 and the support structure 106 along a straight target path 206.

[0065] In the embodiment shown, the actuator wheel 305 exerts different amounts of radial force on the filament 111 at different points around its circumference. For example, contact line segment 401 is the line segment on the circumference of actuator wheel 305 where actuator wheel 305 first contacts the length of filament 111. The radial force of actuator wheel 305 on filament 111 approaches zero.

[0066] On the other hand, nip line segment 402 is the line segment on the circumference of actuator wheel 305 where actuator wheel 305 exerts the greatest radial force on the length of filament 111 .

[0067] Additionally, pinch line segment 403, on the other hand, is a line segment on the periphery of working wheel 305 where working wheel 305 first pinches a length of filament 111 between its periphery and the support structure, substantially restricting any movement of the filament parallel to working wheel axis 312. It will be clear to one of ordinary skill in the art in view of this disclosure how to determine, either theoretically or experimentally, the location of the pinch line segment in any embodiment. Pinch line segment 403 is always located on the periphery of working wheel 305 between contact line segment 401 and nip line segment 402.

[0068] In both the prior art and the illustrated embodiment, the robotic arm 103 packs the filament 111 onto the support structure 106 along the target path 206 by steering the actuator wheel 305. However, there are significant differences in how the actuator wheel 305 is steered between the prior art and the illustrated embodiment. In the prior art, the actuator wheel 305 is (i) by moving the working wheel 305 so that the yaw axis, which is the nip axis 311, intersects with the target path 206 and advances along the target path 206; (ii) by rotating the actuator wheel 305 about the yaw axis, the nip axis 311, to maintain the roll axis, the roll axis 314, substantially parallel to the target path 206 at the point where the yaw axis intersects the target path; (iii) rotating the actuator wheel 305 about a roll axis, the roll axis 314, to maintain the pitch axis, the actuator wheel axis 312, substantially parallel to the support structure 106 at the point where the yaw axis, the nip axis 311, intersects with the support structure 106; The vehicle is steered along a target path 206 .

[0069] In the prior art, the nip shaft 311 is (i) perpendicular to the pitch axis, which is the working axle 312; (ii) intersects with the pitch axis of the working axle 312; (iii) intersects with the midpoint of the nip line segment 402;

[0070] 5 is a top view of the relationship of the support structure 106, the target path 206, and the filament 111 after the filament 111 has been packed by the actuating wheel 305 and steered using the nip axis 311 as the yaw axis, as in the prior art. When the nip axis 311 is used as the yaw axis relative to the actuating wheel 305, it has a detrimental effect in that the actuating wheel 305 "drops" the trailing length of the filament 111 in the target path 206 before it is "locked" in place. In particular, when the nip axis 311 is used as the yaw axis relative to the actuating wheel axis 312, the actuating wheel 305 drops the filament width over the curved portion of the target path 206. This is a distinct disadvantage.

[0071] Meanwhile, in the embodiment shown, the actuator wheel 305 is (i) by moving the operating wheel 305 so that the yaw axis, which is the pinch axis 313, intersects with the target path 206 and moves forward along the target path 206; (ii) rotating the actuation wheel 305 about the yaw axis, the pinch axis 313, to maintain the roll axis, the roll axis 314, substantially parallel to the target path 206 at the point where the yaw axis intersects the target path; (iii) rotating the actuating wheel 305 about the roll axis, the roll axis 314, to maintain the pitch axis, the actuating wheel axis 312, substantially parallel to the support structure 106 at the point where the yaw axis, the pinch axis 313, intersects with the support structure 106; The vehicle is steered along a target path 206 . It will be apparent to one of ordinary skill in the art in view of this disclosure how to make and use alternative embodiments in which the actuator wheel 305 is steered in accordance with i, ii, iii, or any combination of i, ii, and iii.

[0072] In the embodiment shown, the pinch shaft 313 is (i) perpendicular to the pitch axis, which is the working axle 312; (ii) has a non-zero offset s from the pitch axis which is the working axle 312 (i.e. does not intersect with the working axle 312); (iii) intersects with the pinch line segment 403 (eg, at the midpoint of the pinch line segment, etc.). Here, s is a positive real number.

[0073] The value of the offset s depends on the instantaneous curvature of the target path 206 at the pinch axis 31 with respect to the pinch axis 313. For example, the offset s has a value of one when the target path 206 is not curved (e.g., straight) as shown in Figure 4, a larger value when the target path is concave as shown in Figure 7, and a smaller value when the target path is convex as shown in Figure 8. In the illustrated embodiment, the value of the offset s is dynamically adjusted as the working wheel 305 is steered along the target path 206. It will be clear to one of ordinary skill in the art in view of this disclosure how to determine the value of the offset s, either theoretically or experimentally.

[0074] 6 is a top view of the relationship of the support structure 106, the target path 206, and the filament 111 after the filament 111 has been packed by the actuation wheel 305 and steered using the pinch axis 313 as a yaw axis, as in the illustrated configuration. In the illustrated embodiment, the periphery of the actuation wheel 305 precisely packs the filament 111 directly onto the target path 206, regardless of the curvature of the target path 206 and the support structure 106.

[0075] FIG. 9 is a flow chart of the operation of the illustrated embodiment.

[0076] In step 901, a technician using CAD software constructs a desired path on the surface of the support structure 106 along which segments of the filament 111 will be dispensed and packed. It will be clear to one of ordinary skill in the art how to accomplish step 901.

[0077] In step 902, the robotic arm 103 and dispensing head 107, under the control of the controller 109, dispense a length of filament 111 along a target path 206 on the support structure 106. It will be clear to one of ordinary skill in the art how to accomplish step 902.

[0078] In step 903, the robotic arm 103 and stuffing tool 108 stuff the length of the provided filament 111 along the target path 206 above that in step 902. Step 903 is shown in detail in FIG. 10 and the accompanying text.

[0079] It will be apparent to one skilled in the art that steps 902 and 903 may be performed simultaneously on different lengths of filament 111.

[0080] FIG. 10 illustrates a flow chart detailing step 904, i.e., stuffing the filament 111 onto the support structure 106 having the stuffing tool 108 by steering the actuator wheel 305 along the filament 111.

[0081] In step 1001, the robotic arm 103 and stuffing tool 108, under the control of the controller 109, move the actuator wheel 305 so that the yaw axis, which is the pinch axis 313, intersects with and advances along the target path 206. It will be clear to one of ordinary skill in the art, given this disclosure, how to make and use embodiments of the present invention to accomplish step 1001.

[0082] In step 1002, the robotic arm 103 and stuffing tool 108, under the control of the controller 109, rotate the actuator wheel 305 about the yaw axis, the pinch axis 313, to maintain the roll axis, the roll axis 314, substantially parallel to the target path 206 at the point where the yaw axis intersects the target path 206. It will be clear to one of ordinary skill in the art given this disclosure how to make and use embodiments of the present invention to accomplish step 1002.

[0083] In step 1003, the robotic arm 103 and stuffing tool 108, under the control of the controller 109, rotate the actuator wheel 305 about the roll axis, which is the roll axis 314, to maintain the pitch axis, which is the actuator wheel axis 312, substantially parallel to the support structure 106 where the yaw axis intersects the support structure 106. It will be clear to one of ordinary skill in the art given this disclosure how to make and use embodiments of the present invention to accomplish step 1003.

Claims

1. providing a filament (111) along a target path (206) onto a surface of a support structure (106); loading the filament onto a support structure having an actuator wheel by advancing the actuator wheel along the filament; The operating wheel is (i) a pitch axis (312) about which the working wheel is symmetric; (ii) a peripheral surface, the peripheral surface being: (ii-a) a nip line segment (402) where the actuation wheel applies a maximum radial force on a first length of the filament; (ii-b) a pinch line segment (403) such that the actuating wheel first clamps a second length of the filament between the circumferential surface and the support structure to limit any movement of the second length parallel to the pitch axis; A peripheral surface comprising: (iii) a yaw axis (313), which is (iii-a) perpendicular to the pitch axis, (iii-b) having an offset s from the pitch axis that is a non-zero positive real number; (iii-c) intersecting the pinch line segment; and the yaw axis, (iv) a roll axis (314) that intersects the pitch axis and the yaw axis and is perpendicular to the pitch axis and the yaw axis; Equipped with The method of claim 1, wherein advancing the actuating wheel comprises moving the actuating wheel such that the yaw axis intersects the target path and advances along the target path.

2. 2. The method of claim 1, wherein steering the actuating wheel further comprises steering the actuating wheel about the yaw axis to maintain the roll axis parallel to the target path at a point where the yaw axis and the target path intersect.

3. 3. The method of claim 1 or 2, wherein steering the actuating wheel further comprises steering the actuating wheel about the roll axis to maintain the pitch axis parallel to the support structure at a point where the yaw axis intersects with the support structure.

4. 4. The method of claim 1, wherein advancing the working wheel further comprises dynamically adjusting the value of the offset s as a function of the curvature of a target path.

5. 4. The method according to claim 1, wherein the filaments are anisotropic fiber reinforced thermoplastic filaments.

6. The method according to any one of claims 1 to 3, wherein the target path is a planar curve.

7. The method of any one of claims 1 to 3, wherein the target path is a non-planar curve.

8. 4. The method of claim 1, wherein the value of the offset s is a function of a cross-sectional dimension of the filament.

9. 4. A method according to claim 1, wherein the value of the offset s is a function of the diameter of the working wheel.

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