Patent Description:
In order to fabricate composite parts, tows of unhardened fiber-reinforced composite materials are precisely laid-up onto a layup mandrel. The mandrel itself must be precisely positioned within a stationary work cell, or the tows will not be placed in desired locations on the mandrel. Therefore, indexing must be performed upon the stationary mandrel in the cell, in order to ensure that the tows do not exhibit an out of tolerance condition, including laps or gaps when they are later placed onto the mandrel. If the mandrel is not in a desired position within the cell, it must be reoriented and re-indexed, which results in increased time and labor.

The abstract of <CIT> states "A method and apparatus for aligning an actual surface with the internal coordinate system of a machine working thereon is disclosed. A part program controls the motions of a tape laying machine for depositing composite tape on the surface of a mandrel marked with a plurality of reference points. A probe assembly is attached to the tape laying head of the machine and can be used to measure the coordinates of the reference points on the mandrel surface relative to the internal coordinate system of the machine. These measurements and corresponding points on a representative surface permit a transformation function to be generated based upon the rotation and translation of one surface with respect to the other. The geometric data of instructions of the part program are transformed from their orientation relative to the reference surface to a new orientation relative to the mandrel surface by the transformation function before being applied to the tape laying machine.

The various examples described herein provide dynamic systems for indexing a lamination machine to a layup mandrel or other rigid tool that proceeds in a process direction during fabrication (e.g., periodically, continuously, etc.). These dynamic systems enable indexing to be performed in environments where the rigid tool is regularly moved, unlike environments that expect a rigid tool to be held stationary within a cell. These dynamic systems may also provide input for modifying Numerical Control (NC) programs, in order to account for deviations of a rigid tool from an expected position and/or orientation. This eliminates the need to re-position the rigid tool if the rigid tool is not perfectly aligned.

One example is a method for indexing a layup mandrel for a composite part. The method includes identifying a surface of a layup mandrel that travels in a process direction during fabrication of a composite part, placing a lamination head in contact with the surface, traversing the surface of the layup mandrel with the lamination head, acquiring a stream of 3D coordinates of the lamination head as the lamination head traverses the surface, characterizing the layup mandrel based on the stream of 3D coordinates, altering a Numerical Control (NC) program that directs layup of fiber reinforced material at the layup mandrel, based on a difference between the alignment of the layup mandrel and a nominal alignment of the layup mandrel.

A further example is a system for indexing a layup mandrel for a composite part. The system includes a lamination head comprising: a roller, a suspension that enables deflection of the roller, a position sensor that measures deflection of the roller, and a dispenser that dispenses tows of fiber-reinforced material. The system further includes a controller that identifies a surface of a layup mandrel that travels in a process direction during fabrication of a composite part, directs the lamination head to place a roller of a lamination head in contact with the surface, directs the lamination head to traverse the surface with the roller, acquires a stream of 3D coordinates of the roller as the roller traverses the surface, determines an alignment of the layup mandrel based on the stream of 3D coordinates, and alters a Numerical Control (NC) program that directs layup of fiber reinforced material at the layup mandrel, based on a difference between the alignment of the layup mandrel and a nominal alignment of the layup mandrel.

A further example is an apparatus for indexing a layup mandrel for a composite part. The apparatus includes a lamination head comprising a roller, a suspension that enables deflection of the roller, a position sensor that measures deflection of the roller, and a dispenser that dispenses tows of fiber-reinforced material.

Other illustrative embodiments and examples (e.g., methods and computer-readable media relating to the foregoing embodiments) may be described below. The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings.

The figures and the following description provide specific illustrative embodiments of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the disclosure and are included within the scope of the disclosure. Furthermore, any examples described herein are intended to aid in understanding the principles of the disclosure, and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the disclosure is not limited to the specific embodiments or examples described below, but by the claims.

Composite parts, such as Carbon Fiber Reinforced Polymer (CFRP) parts, are initially laid-up onto a rigid layup mandrel in multiple layers that together are referred to as a preform. Individual fibers within each layer of the preform are aligned parallel with each other, but different layers exhibit different fiber orientations in order to increase the strength of the resulting composite part along different dimensions. The preform includes a viscous resin that solidifies in order to harden the preform into a composite part (e.g., for use in an aircraft). Carbon fiber that has been impregnated with an uncured thermoset resin or a thermoplastic resin is referred to as "prepreg. " Other types of carbon fiber include "dry fiber" which has not been impregnated with thermoset resin but may include a tackifier or binder. Dry fiber is infused with resin prior to curing. For thermoset resins, the hardening is a one-way process referred to as curing, while for thermoplastic resins, the resin reaches a viscous form if it is re-heated.

<FIG> is a block diagram of a line assembly system <NUM> for a composite part in an illustrative embodiment. Line assembly system <NUM> comprises any system, device, or component operable to iteratively pulse a layup mandrel <NUM> (e.g. for a half-barrel section of fuselage approximately twenty to forty feet long) along a track <NUM> or other pathway in a process direction <NUM> (e.g., via an Autonomous Guided Vehicle (AGV). For example, the layup mandrel <NUM> may be pulsed for its entire length, a fraction of its length (e.g., a few inches), or may be continuously moved in the process direction <NUM>. Line assembly system <NUM> is further capable of laying up a laminate comprising layers of fiber-reinforced material onto the layup mandrel <NUM> (e.g., in pauses between pulses, or during continuous motion of the layup mandrel <NUM>).

In this embodiment, the line assembly system <NUM> includes tracks <NUM>, which transport the layup mandrel <NUM> (or other rigid tool <NUM>) in a process direction <NUM>. The layup mandrel <NUM> includes a first side surface <NUM>, a second side surface <NUM>, and a layup surface <NUM>. A lamination machine <NUM> applies a laminate (not shown in <FIG>) in layup region <NUM> of the layup mandrel <NUM>. This laminate will be hardened into a composite part after the layup mandrel <NUM> is further transported in the process direction <NUM>. The operations of the lamination machine <NUM> and/or other stations disposed in serial along the process direction <NUM> are managed by controller <NUM>. In one embodiment, controller <NUM> determines a progress of the layup mandrel <NUM> along the track <NUM> (e.g., based on input from a technician, in accordance with an automated process such as input from a camera or physical sensor, such as a linear or rotary actuator), and uses this input to manage the operations of the lamination machine <NUM> in accordance with instructions stored in a Numerical Control (NC) program. Controller <NUM> may be implemented, for example, as custom circuitry, as a hardware processor executing programmed instructions, or some combination thereof.

The lamination machine <NUM> moves along a frame <NUM> via actuators <NUM>, and includes a lamination head <NUM> that performs layup of fiber-reinforced material. Lamination head <NUM> places fiber-reinforced material upon layup mandrel <NUM> or a prior placed ply of fiber-reinforced material to create a lamination. The lamination head <NUM> includes a roller <NUM> that travels along a layup surface <NUM> of the layup mandrel <NUM>, and further includes a suspension <NUM> which permits limited displacement of the roller <NUM> along all three axes. The suspension <NUM> supports the roller <NUM> while permitting limited deflection of the roller <NUM> by the layup surface <NUM>. For example, the suspension <NUM> may press the roller <NUM> into the layup surface <NUM>, resulting in deflection from a default position if the layup surface <NUM> is above or below an expected position. The lamination head <NUM> further includes a position sensor <NUM> (e.g., a linear sensor, laser sensor, infrared sensor, etc.) that detects displacement of the roller <NUM> along three dimensions. Lamination head <NUM> further includes a dispenser <NUM> which applies tows of unidirectional fiber reinforced material (e.g., CFRP) in accordance with instructions from the NC program <NUM> stored in controller <NUM>.

Because the layup mandrel <NUM> may be tens of feet long, even small angular deviations of the layup mandrel <NUM> from an expected orientation result in substantial differences in the locations where tows are placed by the lamination machine <NUM>. For example, an angular deviation of less than a degree may result in inches of positional offset at one or more locations on the layup mandrel <NUM>. This presents a problem because tows are expected to be placed in precise locations and orientations at the layup mandrel <NUM> (e.g., locations that are specified to within fractions of an inch). Furthermore, gaps and/or overlaps between tows beyond tolerance are not permissible. To address these concerns and ensure that layup is performed in a desired manner without a need to reorient the layup mandrel <NUM>, the line assembly system <NUM> includes one or more of the following components discussed below to facilitate indexing of the layup mandrel <NUM> to the lamination machine <NUM>. Furthermore, localized variations may exist at the layup mandrel <NUM>, for example if a component placed at the layup mandrel <NUM> deviates from an expected position. In one embodiment, the roller <NUM> of the lamination head <NUM> utilizes the position sensor <NUM> to determine displacement over time as the roller <NUM> proceeds along a layup surface <NUM> of the layup mandrel <NUM>. For example, the roller <NUM> may traverse first side surface <NUM> or second side surface <NUM> by following a nominal (expected) path (i.e., a path comprising a series of 3D coordinates), and deviations from the nominal path <NUM> may be recorded by the position sensor <NUM> at each of multiple locations along the surface(s) that were traversed. Controller <NUM> may then alter the NC program <NUM> to account for these differences. It is understood that NC program <NUM> includes a portion that controls the indexing operations described herein as well as a portion that controls the placement of composites materials such as fiber tows.

In a further embodiment, the lamination machine <NUM> is placed a predetermined and precisely known offset O from an indexing head <NUM>. In various embodiments, lamination machine <NUM> includes an indexing head <NUM>, or lamination machine <NUM> swaps out its lamination head <NUM> for an indexing head <NUM>. In such an embodiment, the indexing head <NUM> includes an indexing end <NUM> that traverses grooves, for example first groove <NUM> and/or second groove <NUM>, that have been precisely placed onto/machined into the layup mandrel <NUM> (or other rigid tool <NUM>) (e.g., to within tolerance), and a sensor <NUM> records positional deviations from an expected nominal path of the indexing end <NUM> as the indexing end <NUM> traverses the first groove <NUM> and/or second groove <NUM>. The deviations may be recorded, for example, once per half-inch of travel of the roller <NUM>, and may be recorded to tolerance requirements. This information may be utilized by controller <NUM> to update the NC program <NUM>.

In one embodiment, indexing is performed at least according to the following description. A layup mandrel <NUM> (also referred to herein as a tool, a rigid tool <NUM>, and an arcuate tool) is carried upon a track <NUM> comprising a rail system (e.g., embedded within the floor, affixed to the floor, etc.). The rails are positioned in locations known to the controller <NUM>. The layup mandrel <NUM> has been fabricated according to precise dimensions, and this precise layup enables the layup mandrel <NUM> to be precisely located based on a traversal of its surface(s) (e.g., first side <NUM> and/or second side <NUM>) or groove(s) (e.g., first groove <NUM> and/or second groove <NUM>). Thus, once this rigid tool <NUM> has been traversed by a roller <NUM> or indexing head <NUM>, the 3D position and orientation of the rigid tool <NUM> is known, without the need for a full scan via probes or optical technology at each station in an assembly line.

Traversal by a roller <NUM> or indexing head <NUM> therefore operates as a short cut to characterizing surface geometry and orientation, without the need for a full scan via probes or optical technology at each station, such as lamination station <NUM>, in an assembly line. This technique benefits from the rigidity of the layup mandrel <NUM> (or its lack of deflection, particularly deflection outside of tolerance) as it passes through the lamination machine <NUM> from one micro pulse to the next. A micro pulse is an advancement of the layup mandrel <NUM> by a distance less than the length of the layup mandrel <NUM>. A pulse is an advancement of the layup mandrel <NUM> by a distance equal to or greater than the length of the layup mandrel <NUM>. The preciseness of the tooling, the layup upon the tooling, and the lack of change to the tooling and the layup due to rigidity of the system from one micro pulse to the next enables characterization of the structure being micro pulsed, without rescanning after each pulse. The pulsing does not sufficiently disrupt the configuration of the layup mandrel <NUM> nor does it disrupt a preform upon it. Hence, the technique of characterization may be repeated successfully after each micro pulse.

Because of the precise indexing performed, the lamination machine <NUM> (or another other tool) at a station in an assembly line knows exactly where it is relative to the rigid tool <NUM>, such as layup mandrel <NUM>, before work is performed at the layup mandrel <NUM>. The 3D position and orientation of the rigid tool <NUM> is then established or indexed into any NC programming or other automated system in use at the station. After initially establishing this information, downstream stations or tools may assume that the layup mandrel <NUM> has not changed its orientation and/or contour as it proceeds, or pulses, along the assembly line. Therefore, no setup time or scanning is needed after each micro pulse of the rigid tool <NUM> by a distance in the process direction <NUM> (e.g., a micro pulse of one foot, several inches, a pulse of an entire length of the rigid tool <NUM>, etc.). That is, because the precise shape of the rigid tool <NUM> is already known (i.e., to within tolerance), traversing sides <NUM>, <NUM>, traversing grooves <NUM>, <NUM> and/or layup surfaces <NUM> are precisely fabricated into the layup mandrel <NUM> enables the controller <NUM> to determine a precise orientation and/or location of the rigid tool <NUM> (e.g., to within tolerance) relative to a lamination machine <NUM>. When the two are in a known relationship, layup operations at the lamination machine <NUM> can be altered to accommodate the rigid tool <NUM>.

In one embodiment, lamination machine <NUM> comprises one of multiple stations that are disposed along the tracks <NUM> and are separated in the process direction <NUM> by less than the length of the rigid tool <NUM>. Work performed by other stations may comprise performing additional layup, inspecting a green (uncured) laminate, and/or performing other tasks.

Illustrative details of the operation of line assembly system <NUM> will be discussed with regard to <FIG>. Assume, for this embodiment, that a layup mandrel <NUM> has proceeded along tracks <NUM> to a lamination machine <NUM>, but that the precise position and orientation (e.g., to a fraction of an inch and to the hundredth of a degree) of the layup mandrel <NUM> is not known. Thus, if the lamination machine <NUM> proceeds according to a "default" NC program and the layup mandrel <NUM> has even a slight deviation from nominal, laps or gaps may occur that are not within a desired tolerance, and the resulting laminate may have to be reworked.

<FIG> is a flowchart illustrating a method <NUM> for operating an indexing system based on the position of a roller <NUM> for a lamination head <NUM> in an illustrative embodiment. The steps of method <NUM> are described with reference to line assembly system <NUM> of <FIG>, but those skilled in the art will appreciate that method <NUM> may be performed in other systems. The steps of the flowcharts described herein are not all inclusive and may include other steps not shown. The steps described herein may also be performed in an alternative order.

Initially, a layup surface <NUM> of the layup mandrel <NUM> is identified <NUM> by controller <NUM>. The layup mandrel <NUM> travels in a process direction <NUM> during fabrication of a composite part. For example, the layup mandrel <NUM> may be periodically "micro pulsed" a predetermined distance in the process direction <NUM> over time (e.g., one foot every fifteen minutes, and/or pulsed the entire length of the layup mandrel <NUM> every two hours, etc.), or may be continuously moved in the process direction <NUM> at a predetermined rate (e.g., one inch per minute). The controller <NUM> may identify the layup surface <NUM> of the layup mandrel <NUM> based on preprogrammed information indicating an expected start position of first side surface <NUM> or second side surface <NUM> of the layup mandrel <NUM>, or may visually inspect the layup mandrel <NUM> to identify the first side surface <NUM> and/or second side surface <NUM>.

The controller <NUM> directs the lamination machine <NUM> to place <NUM> itself (i.e., via the roller <NUM>) in contact with first side surface <NUM>, or second side surface <NUM>. The lamination head <NUM> traverses <NUM> the first side surface <NUM>, or second side surface <NUM> with the roller <NUM>. During this process, the layup mandrel <NUM> remains in position. The roller <NUM> proceeds along a nominal path indicative of an expected position of the layup mandrel <NUM> along its length. As used herein, a "path" is a series of positions that may be measured and compared to a stream of 3D coordinates. If the layup mandrel <NUM> is not in an expected position and/or orientation, the roller <NUM> encounters physical resistance from the surface being traversed, and this physical resistance causes the roller <NUM> to deflect from the nominal path. These deflections are indicative of a surface geometry, such as contour, of the layup surface <NUM>, first side surface <NUM>, and second side surface <NUM>, and are recorded by the position sensor <NUM>.

In the next step, controller <NUM> acquires <NUM> a stream of three dimensional (3D) coordinates of the lamination head <NUM> (i.e. the roller <NUM>) as the lamination head <NUM> traverses the layup surface <NUM>. This may comprise acquiring a coordinate from the position sensor <NUM> periodically over time or space (e.g., every tenth of an inch, every tenth of a second, etc.), and storing the stream of coordinates in memory.

Continuing, the controller <NUM> characterizes <NUM> (e.g., determines an alignment and/or shape of the layup mandrel <NUM> to within a tolerance) based on the stream of 3D coordinates. This may be performed by loading a known shape of the layup mandrel <NUM> into memory, and applying a mathematical transform to a nominal alignment of the shape that causes the shape to match the stream of 3D coordinates. In further embodiments, the alignment of the layup mandrel <NUM> is more generally determined as either aligned or not aligned, based whether the stream of 3D coordinates is within a tolerance of the nominal path (e.g., a fraction of an inch of the nominal path).

Finally, the controller <NUM> alters <NUM> the NC program <NUM> that directs layup of fiber reinforced material at the layup mandrel <NUM>, based on a difference between the alignment of the layup mandrel <NUM> and a nominal alignment of the layup mandrel <NUM>. In one embodiment, this comprises applying a mathematical transform to coordinates found in instructions in the NC program <NUM>, based on a mathematical transform that was determined earlier. In a further embodiment, this comprises identifying locations in the NC program <NUM> that correspond with locations in the nominal path, and altering the locations in the NC program <NUM> by an amount equal to the differences detected from the nominal path in the stream of 3D coordinates. In yet another embodiment, the NC program <NUM> is altered in real time as needed to accommodate the laid down thickness of the laid down material already placed upon the layup mandrel <NUM> at a particular point during the layup process.

Method <NUM> provides a technical benefit over prior systems and techniques, because it enables a rigid tool <NUM> to be precisely indexed to a lamination machine <NUM>, without the need for additional indexing equipment of any kind. In particular, probes and other devices are not needed to perform indexing, and the lamination machine <NUM> is capable of adapting to changes from a nominal orientation, without having to re-orient a layup mandrel <NUM>. In an embodiment, the layup mandrel <NUM> may weigh hundreds or even thousands of pounds and would be difficult to re-orient as needed.

<FIG> is a perspective view of lamination head <NUM> traversing first side surface <NUM> of a layup mandrel <NUM> in an illustrative embodiment. According to <FIG>, the layup mandrel <NUM> proceeds in a process direction <NUM>, and includes first side surface <NUM> and second side surface <NUM>. The lamination head <NUM> will perform layup of fiber-reinforced material along region <NUM> between first side surface <NUM> and second side surface <NUM>, and is mounted to an extensible arm <NUM> (e.g., a robotic arm formed from a kinematic chain of rigid bodies and actuators, a telescopic arm, etc.) that moves laterally with respect to frame <NUM> as frame <NUM> moves along track <NUM>. The frame <NUM> moves backward <NUM> and forward <NUM> with respect to the process direction <NUM> along the tracks <NUM> and/or supports (not shown). The lamination head <NUM> in <FIG> is shown as performing an initial indexing operation by traversing the first side surface <NUM> and second side surface <NUM>, prior to initiating layup at the layup mandrel <NUM>. These operations may be performed during continuous motion of the layup mandrel <NUM> (e.g., at a slow rate of speed), or during pauses between pulses of the layup mandrel <NUM> in the process direction <NUM>. Furthermore, these operations could also occur during each micro pulse, pulse and/or layup operations may occurs during pauses between micro pulses or pulses.

<FIG> is a top view of a rigid tool <NUM> (e.g., layup mandrel <NUM>) that is not within a nominal orientation in an illustrative embodiment, and corresponds with view arrows <NUM> of <FIG>. As shown in <FIG>, the layup mandrel <NUM> exhibits an angular offset θ from a nominal alignment <NUM> of less than one degree (the less than one degree offset is shown in exaggeration in <FIG>). However, the layup mandrel <NUM> has a length L (e.g., twenty-five feet, forty feet, etc.). This means that differences in position (Δ) accrue that result in deviations of region <NUM> from nominal layup region <NUM>, and these differences in position may exceed a desired tolerance. Hence, if a default NC program is utilized to lay up fiber reinforced material. Tows of fiber reinforced material result in out-of-tolerance conditions when not placed as desired, necessitating re-work of a laminate prior to or after curing.

<FIG> is a perspective view of a roller <NUM> traversing a surface <NUM> that varies with respect to an expected nominal path in an illustrative embodiment. <FIG> corresponds with view arrows <NUM> of <FIG>. In this embodiment, a surface <NUM> includes variations from a nominal path <NUM>. As a lamination head <NUM> attempts to follow the nominal path with a roller <NUM>, the variations in the surface <NUM> enforce variations in position (Δx, Δy, and Δz) upon the roller <NUM>. A sensor (e.g., a sensor that measures positional offsets of components of a suspension that enable the roller <NUM> to deflect) measures these positional offsets for later comparison to a nominal path. In embodiments where the sensor is a rotary sensor that measures degrees of travel/rotation of the roller <NUM>, a larger radius R of the roller <NUM> may result in reduced precision of measurement. The radius R of the roller <NUM> may range from less than an inch to several inches. The sensor may measure these offsets to a fraction of an inch along each axis, and may do so at any suitable rate (e.g., kilohertz, megahertz, etc.). In one embodiment, an example of surface <NUM> is a first side surface <NUM> of layup mandrel <NUM>, and the lamination head <NUM> is further operated to traverse second side surface <NUM> of the layup mandrel <NUM>. In such a case, a controller <NUM> of the lamination head <NUM> acquires a second stream of 3D coordinates of the roller <NUM> as the roller <NUM> traverses the second surface. <FIG> is a view of a roller <NUM> traversing a curved surface in an illustrative embodiment.

According to <FIG>, a lamination head <NUM> traverses the surface <NUM> and the surface <NUM> of a layup mandrel <NUM>. By traversing two surfaces at different sides of the layup mandrel <NUM>, an orientation of the layup mandrel <NUM> along X, Y, and Z axes may be rapidly and precisely determined.

<FIG> is a view of a roller <NUM> traversing a laid-up laminate <NUM> in an illustrative embodiment. According to <FIG>, a position of the roller <NUM> as it follows a surface <NUM> defined by laminate <NUM> is actively tracked during layup to acquire a second stream of 3D coordinates. This information enables a thickness of a resulting laminate <NUM> to be determined, and this information (e.g., the second stream of 3D coordinates, along with any offset information that was previously determined) is passed to a downstream lamination machine <NUM> having a downstream lamination head <NUM> (e.g., as shown in <FIG> below) separated from the lamination head <NUM> by a distance D in the process direction <NUM>. The downstream lamination machine <NUM> updates its own NC program using measurements from the lamination head <NUM> and/or downstream lamination head <NUM>.

<FIG> is a view of a roller <NUM> traversing a laid-up laminate <NUM> that is laid-up around a tight radius in an illustrative embodiment. According to <FIG>, a roller <NUM> of a lamination head <NUM> traverses surfaces of layup mandrel <NUM> and/or laid-up laminate <NUM> within desired tolerances, such as surfaces that correspond with an outer radius of a corner <NUM> of a laminate <NUM>. This may be performed via multiple passes of the roller <NUM> at different arcuate portions of the curve <NUM>, and integrating the resulting sensor data to characterize the curve <NUM> along the length of the laminate <NUM>, which wraps around edge <NUM> and edge <NUM> of layup mandrel <NUM>. This operation may be performed after receiving laminate <NUM> from an upstream station, such as lamination station <NUM> during layup, or after layup before the layup mandrel <NUM> proceeds to a downstream lamination machine <NUM>. The information may then be utilized to alter an existing NC program <NUM>. For example, if the information indicates that a concave radius (not shown) is too small, additional layers may be applied to pad out the outer radius, or the lamination head <NUM> and NC program <NUM> are adjusted to account for the difference in geometry. Likewise, if the information indicates that a convex radius R1 is too large, additional layers may be applied to pad out the outer radius to a desired R1, or the lamination head <NUM> and NC program <NUM> are adjusted to account for the difference in geometry.

<FIG> is a flowchart illustrating a method <NUM> for operating an indexing head <NUM> that traverses grooves <NUM>, <NUM> in a rigid tool <NUM> in an illustrative embodiment. According to <FIG>, method <NUM> includes identifying <NUM> a groove <NUM> that is within a rigid tool <NUM> (e.g., a layup mandrel <NUM> or other component). The groove <NUM> extends in a process direction <NUM> traveled by the rigid tool <NUM> during fabrication of a composite part, and may exhibit an eighth to a quarter inch or more of depth.

An indexing head <NUM> is placed <NUM> into the groove <NUM>. For example, the indexing head <NUM> may be pressed into the groove <NUM> at a desired level of pressure (e.g., twenty-five pounds per square inch). This physically unites an indexing end <NUM> of the indexing head <NUM> with the groove <NUM>, which means that if the groove <NUM> proceeds in an unexpected direction from a nominal path, it causes the indexing head <NUM> to deviate as well. The position of the indexing head <NUM> is measured by a sensor <NUM> over time. Hence, the deviations are capable of being determined by analyzing a stream of 3D coordinates from the sensor <NUM>.

The groove is traversed <NUM> via the indexing head <NUM>. That is, controller <NUM> operates the indexing head <NUM> to move along a nominal path. If the groove <NUM> deviates from the nominal path, it causes the indexing head <NUM> to deflect from its expected position.

A stream of 3D coordinates of the indexing head <NUM> is acquired <NUM> as the indexing head <NUM> traverses the groove <NUM>. Or in addition to or instead of the 3D coordinates, an arc and orientation of the arc of the indexing head <NUM> is acquired in <NUM> as the indexing head <NUM> traverses the groove <NUM>. This may comprise controller <NUM> sampling input from the sensor <NUM> at a desired rate (e.g., multiple times per second, multiple times per inch, etc.).

An alignment of the rigid tool <NUM> is determined in <NUM> based on the stream of 3D coordinates that was acquired in <NUM>. The determining <NUM> step may be performed in a similar manner to that of method <NUM> provided above.

A Numerical Control (NC) program <NUM> that directs work at the rigid tool <NUM> is altered in <NUM>, based on a difference between the alignment of the rigid tool <NUM> and a nominal alignment of the rigid tool <NUM>. The altering <NUM> step may be performed in a similar manner to the altering <NUM> step described above.

<FIG> is a perspective view of an indexing head <NUM> that follows one or more grooves <NUM> and <NUM> in a rigid tool <NUM> in order to index the rigid tool <NUM> having a layup region <NUM> in an illustrative embodiment. The groove <NUM> follows a series of non-repeating curves <NUM>. In this embodiment, indexing head <NUM> moves perpendicular to the process direction <NUM> along frame <NUM>, and frame <NUM> moves parallel to the process direction <NUM> along tracks <NUM>. The rigid tool <NUM> proceeds downstream in the process direction <NUM> to downstream lamination machine <NUM> having a lamination head <NUM> (i.e., a second, or downstream, lamination head). In this embodiment, the downstream lamination machine <NUM> is separated from the upstream lamination machine <NUM> by a distance D (<FIG>) in the process direction <NUM>.

As shown in <FIG>, each of the grooves <NUM>, <NUM> may exhibit a unique series of non-repeating curves. Hence, each location along the groove <NUM>, <NUM> is uniquely identifiable based on curvature information. By analyzing changes in position of the stream of 3D coordinates, an exact position along the rigid tool <NUM> may therefore be determined (e.g., to the inch, to a fraction of an inch, etc.). In embodiments wherein the grooves <NUM>, <NUM> are each unique, the exact groove <NUM>, <NUM> being traversed may also be determined, based on the curvature of the groove <NUM>, <NUM>. In further embodiments, features of the groove <NUM>, <NUM> are used to communicate information. This information may include width, depth, angle, or slope of the groove walls, or a cross sectional shape such as a triangular, square, rectangular or half circle shape, or an ellipse. This information may further include varying the cross-sectional shape along the groove <NUM>, <NUM>, placing notches or splines along the walls of the groove <NUM>, <NUM>, or applying magnetic fields with strength that varies down the groove <NUM>, <NUM>, etc. This information may be used to indicate specific regions along the length of each groove <NUM>, <NUM>.

<FIG> is a top view of an indexing head <NUM> that follows a groove <NUM>, <NUM> in a rigid tool <NUM> in order to index the rigid tool <NUM> in an illustrative embodiment, and corresponds with view arrows <NUM> of <FIG>. According to <FIG>, each of the grooves <NUM> and <NUM> exhibits a unique, non-repeating series of curves. The rollers <NUM> discussed herein may be made from rigid materials that do not scratch or damage the underlying rigid tool <NUM>. As the rigid tool <NUM> may be made from steel or other metals, the rollers <NUM> may be made, for example, from high-density polyurethane. <FIG> are front views of different rollers for indexing heads <NUM> that traverse grooves in rigid tools in illustrative embodiments, and correspond with view arrows <NUM> of <FIG>.

Specifically, <FIG> illustrates a roller <NUM> having a triangular notch <NUM> for rolling within a triangular groove <NUM>, <FIG> illustrates a roller <NUM> having a rectangular notch <NUM> for rolling within a rectangular groove <NUM>, and <FIG> illustrates a roller <NUM> with a roller ball <NUM> having a semicircular notch <NUM> for traversing a semicircular groove <NUM>.

<FIG> is a cut-through view of an indexing head <NUM> having a roller <NUM> carried by a suspension <NUM> in an illustrative embodiment, and corresponds with view arrows <NUM> of <FIG>. The roller <NUM> includes a notch <NUM> that is triangular in cross-section (corresponding to roller <NUM>) and continues along the curvature of the roller <NUM>, for rolling along a triangular groove. Roller <NUM> and roller <NUM> are capable of replacing roller <NUM> if needed to match groove <NUM> or groove <NUM>, respectively. The roller <NUM> rotates about a bar <NUM>, and linear travel of the roller <NUM> is measured by rotational sensors <NUM>. Suspension cylinders <NUM> and <NUM> (and additional suspension cylinders along an additional axis proceeding into the page) absorb deviations in position caused by the groove when the groove does not follow a nominal path, and these deviations may then be measured by a position sensor. In further embodiments, contours <NUM>-<NUM> and <NUM>-<NUM> (<FIG>) are added to the groove or groove surface to convey additional information to different stations. In further embodiments, multiple grooves <NUM> and/or <NUM> are added to the rigid tool <NUM> to convey additional information to different stations, such as lamination station <NUM> and downstream lamination station <NUM>. For example, each groove may be utilized by a different station for different indexing purposes to conform with different sets of constraints. The information being conveyed by the grooves <NUM> and <NUM> include, but are not limited to layup patterns, ramp rates, ply orientations and other ply or laminate specifics.

Additional embodiments have portions of the grooves <NUM> and <NUM> aimed at conveying information only to lamination station <NUM> and other portions aimed conveying information only to downstream lamination station <NUM>.

<FIG> is a flowchart illustrating a method <NUM> for operating an indexing head <NUM> that traverses a circumferential groove <NUM> in an arcuate tool <NUM> in an illustrative embodiment. The operations of method <NUM> are described with regard to the system depicted in <FIG> and includes identifying <NUM> an arcuate tool <NUM> that travels in a process direction <NUM> during fabrication of a composite part. Method <NUM> is similar to method <NUM> of <FIG> provided above, except that the grooves <NUM>, <NUM> proceed circumferentially with respect to arcuate tool <NUM>. A groove <NUM> is identified <NUM> within the arcuate tool <NUM> that extends along a portion of the arcuate tool <NUM>. An embodiment has groove <NUM> is identified <NUM> within the arcuate tool <NUM> that extends along an arcuate portion of the arcuate tool <NUM>. This may comprise utilizing a camera to detect a position of a groove <NUM> at the arcuate tool <NUM>, placing <NUM> an indexing end <NUM> of an indexing head <NUM> over the groove <NUM>, or placing <NUM> the indexing head <NUM> at a location where the groove <NUM> will mate with the indexing end <NUM> when the arcuate tool <NUM> travels in the process direction <NUM>.

As mentioned, an indexing end <NUM> is placed <NUM> into the groove <NUM>. This may further include placing <NUM> an indexing end <NUM> of a second indexing head <NUM> into a second groove <NUM>. In such an embodiment, the indexing head <NUM> is downstream of the second indexing head <NUM>, and a lamination machine <NUM> is disposed between the indexing heads <NUM>, <NUM>.

The arcuate tool <NUM> is rotated <NUM> relative to the indexing head <NUM> such that the indexing end <NUM> traverses the groove <NUM>. In one embodiment, this comprises rotating the arcuate tool <NUM> about its central axis or via a rotatable support <NUM> (held by a frame <NUM>) that is configured to retain the arcuate tool <NUM>, and that is configured to rotate the arcuate tool <NUM> relative to the indexing head <NUM> such that the indexing end <NUM> traverses the groove <NUM>. In a further embodiment, this comprises moving the indexing heads <NUM> and <NUM> circumferentially about the arcuate tool <NUM>. In embodiments where the arcuate tool <NUM> is moved continuously in the process direction <NUM>, the indexing heads <NUM> and <NUM> match the speed of the arcuate tool <NUM> to remain in position with respect to the arcuate tool <NUM> as the arcuate tool <NUM> moves.

A stream of 3D coordinates of the indexing head <NUM>, <NUM> is acquired <NUM> as the indexing head <NUM>, <NUM> traverses the respective groove <NUM>, <NUM>. This input is acquired from positional sensors (not shown in <FIG> but similar to sensors <NUM> shown in <FIG>) at the indexing heads <NUM>, <NUM>. In one embodiment, a single indexing head traverses multiple grooves of the arcuate tool <NUM> (i.e., by traversing first groove <NUM> over a first period of time, and by traversing second groove <NUM> over a second period of time). This results in multiple streams of 3D coordinates for analysis.

An alignment of the arcuate tool <NUM> is determined <NUM> based on the stream of 3D coordinates. This may be performed in a similar manner to the characterizing <NUM> step of method <NUM> discussed above. A Numerical Control (NC) program <NUM> that directs work at the arcuate tool <NUM> is altered <NUM>, based on a difference between the alignment of the arcuate tool <NUM> and a nominal alignment of the arcuate tool <NUM> as represented by 3D coordinates associated with the nominal path. This may be performed in a similar manner to the altering <NUM> step of method <NUM> discussed above.

With the NC program <NUM> adjusted, the lamination machine <NUM> proceeds to operate its lamination head <NUM> to lay up one or more tows <NUM> for a laminate. The laminate is then hardened into a composite part, such as a half-barrel section of an aircraft fuselage.

Method <NUM> may be particularly valuable in environments wherein a heavy arcuate tool <NUM> (e.g., weighing multiple tons) is held at one end by support <NUM>. In such circumstances, a weight of the arcuate tool <NUM> causes a minor deflection/angular deviation along the length of the arcuate tool <NUM>.

In still further embodiments, grooves <NUM>, <NUM>, <NUM>, <NUM> comprise continuous protrusions from rigid tool <NUM>, arcuate tool <NUM> that are mated to indexing heads <NUM>, <NUM>, <NUM> that have pairs of rollers (e.g., one roller on either side of the protrusion). In yet further embodiments, the grooves <NUM>, <NUM>, <NUM>, <NUM> are not physical grooves, but rather are painted or colored lines that are tracked by sensors in the form of high-precision cameras. The sensors may further comprise distancing sensors such as laser or ultrasonic sensors that track across the rigid tool <NUM>, arcuate tool <NUM> while measuring distance. Thus, indexing may be performed based on imaging from sensors that follow visually distinct patterns at rigid tools, without actually contacting those rigid tools and particularly by indexing head <NUM>.

<FIG> is an example report <NUM> indicating a difference between a nominal position and actual position of one of the indexing heads described herein in an illustrative embodiment. The report comprises a stream of 3D coordinates acquired over time. For each measured 3D coordinate, the controller compares the coordinate to an expected 3D coordinate, and calculates a difference between the measured 3D coordinate and the expected 3D coordinate. The controller then alters instructions in an NC program for performing work (e.g., layup) at the rigid tool being indexed, by identifying positions indicated in the instructions, and applying corresponding differences in position to the instructions.

Referring more particularly to the drawings, embodiments of the disclosure may be described in the context of aircraft manufacturing and service in method <NUM> as shown in <FIG> and an aircraft <NUM> as shown in <FIG>. During pre-production, method <NUM> may include specification and design <NUM> of the aircraft <NUM> and material procurement <NUM>. During production, component and subassembly manufacturing <NUM> and system integration <NUM> of the aircraft <NUM> takes place. Thereafter, the aircraft <NUM> may go through certification and delivery <NUM> in order to be placed in service <NUM>. While in service by a customer, the aircraft <NUM> is scheduled for routine work in maintenance and service <NUM> (which may also include modification, reconfiguration, refurbishment, and so on). Apparatus and methods embodied herein may be employed during any one or more suitable stages of the production and service described in method <NUM> (e.g., specification and design <NUM>, material procurement <NUM>, component and subassembly manufacturing <NUM>, system integration <NUM>, certification and delivery <NUM>, service <NUM>, maintenance and service <NUM>) and/or any suitable component of aircraft <NUM> (e.g., airframe <NUM>, systems <NUM>, interior <NUM>, propulsion system <NUM>, electrical system <NUM>, hydraulic system <NUM>, environmental <NUM>).

As shown in <FIG>, the aircraft <NUM> produced by method <NUM> may include an airframe <NUM> with a plurality of systems <NUM> and an interior <NUM>. Examples of systems <NUM> include one or more of a propulsion system <NUM>, an electrical system <NUM>, a hydraulic system <NUM>, and an environmental system <NUM>. Any number of other systems may be included. Although an aerospace example is shown, the principles outlined in this disclosure may be applied to other industries, such as the automotive industry.

As already mentioned above, apparatus and methods embodied herein may be employed during any one or more of the stages of the production and service described in method <NUM>. For example, components or subassemblies corresponding to component and subassembly manufacturing <NUM> may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft <NUM> is in service. Also, one or more apparatus embodiments, method embodiments, or a combination thereof may be utilized during the subassembly manufacturing <NUM> and system integration <NUM>, for example, by substantially expediting assembly of or reducing the cost of an aircraft <NUM>. Similarly, one or more of apparatus embodiments, method embodiments, or a combination thereof may be utilized while the aircraft <NUM> is in service, for example and without limitation during the maintenance and service <NUM>. Thus, the described elements may be used in any stages discussed herein, or any combination thereof, such as specification and design <NUM>, material procurement <NUM>, component and subassembly manufacturing <NUM>, system integration <NUM>, certification and delivery <NUM>, service <NUM>, maintenance and service <NUM> and/or any suitable component of aircraft <NUM> (e.g., airframe <NUM>, systems <NUM>, interior <NUM>, propulsion system <NUM>, electrical system <NUM>, hydraulic system <NUM>, and/or environmental <NUM>.

Claim 1:
A method (<NUM>) for indexing a layup mandrel (<NUM>) for a composite part, the method (<NUM>) comprising:
identifying (<NUM>) a first side surface (<NUM>) of a layup mandrel (<NUM>) that travels in a process direction (<NUM>) during fabrication of a composite part;
placing (<NUM>) a lamination head (<NUM>) in contact with the first side surface (<NUM>);
traversing (<NUM>) the first side surface (<NUM>) of the layup mandrel (<NUM>) with the lamination head (<NUM>);
acquiring (<NUM>) a stream of 3D coordinates of the lamination head (<NUM>) as the lamination head (<NUM>) traverses the first side surface (<NUM>);
characterizing (<NUM>) the layup mandrel (<NUM>) based on the stream of 3D coordinates; and
altering (<NUM>) a Numerical Control program (<NUM>) that directs layup of fiber reinforced material at the layup mandrel (<NUM>), based on a difference between an alignment of the layup mandrel (<NUM>) and a nominal alignment of the layup mandrel (<NUM>).