Automated fabric layup system and method

To apply a resin impregnated fabric to a substrate, a device includes a surface having a layer of material and a first edge. The surface moves relative to the substrate and to conform to the substrate. The layer of material is compatible for use with the resin. The first edge is disposed at the front of the surface relative to the movement of the device to the fabric. The first edge is curved with a center portion of the first edge being relatively forward of a pair of side portions of the first edge.

FIELD OF THE INVENTION

The present invention generally relates to a device, system and method of fabricating a composite item. More particularly, the present invention pertains to an automated fabric layup device and system and a method of use.

BACKGROUND OF THE INVENTION

Composite structures are typically constructed from multiple layers or plies. The plies, in turn, are generally made up of a series of courses that slightly overlap or abut one another. These courses may include a variety of materials such as glass, aramid, and carbon fiber, various other fibers, and the like. In addition, the fibers may be oriented in a single direction or woven into a fabric. The course material may further be pre-impregnated with a resin and are often dispensed from a roll. In roll form, the course material typically includes a separator film or backing film of plastic, paper, or the like. This backing film generally prevents resin coated or pre-impregnated course material (prepreg) from adhering to itself.

The courses are generally laid upon the form or tool along a “natural path” of the course material. The term “natural path” refers to the path the course material would follow when rolled out on to the surface of the tool. Deviations from the natural path are generally achieved by applying force across the width of the course material. When the force applied exceeds the flexing capacity of the material, wrinkles or bridges form in the course material. In addition, the wider the course is, the more prone the course material is to wrinkle. However, in general, it is advantageous to utilize relatively wide course material so as to increase layup rates. Conventional methods of constructing contoured composite structures from fabric course material employ skilled technicians to hand lay the fabric. These technicians pull on the edges and corners of the fabric to deform or trellis the weave of the fabric. In this manner, the fabric is induced to conform to the contour.

When laying a course adjacent to a previously applied course the natural path of the course across a contour may cause the courses to diverge or converge. In order to prevent gaps or excessive overlap, the side edge or profile of the course is trimmed to maintain an appropriate relationship. Conventional methods of trimming or profiling also generally employ skilled technicians to perform these tasks. As a result, hand layups of contoured surfaces with fabric course material is expensive and time consuming.

Accordingly, it is desirable to provide a system for generating composite items that is capable of overcoming the disadvantages described herein at least to some extent.

SUMMARY OF THE INVENTION

The foregoing needs are met, to a great extent, by the present invention, wherein in some embodiments an automated lamination system for generating composite items from fabric ply material and a method of using such a system is provided.

An embodiment of the present invention relates to a device to apply a resin impregnated fabric to a substrate. The device includes a surface having a layer of material and a first edge. The surface moves relative to the substrate and to conform to the substrate. The layer of material is compatible for use with the resin. The first edge is disposed at the front of the surface relative to the movement of the device to the fabric. The first edge is curved with a center portion of the first edge being relatively forward of a pair of side portions of the first edge.

Another embodiment of the present invention pertains to a device to apply a resin impregnated fabric to a substrate. The device includes a supply reel, a cutting system, and a pressure shoe. The supply reel supplies the resin impregnated fabric. The cutting system cuts resin impregnated fabric. The pressure shoe presses the resin impregnated fabric on to the substrate. The pressure shoe includes a surface having a layer and a first edge. The surface moves relative to the substrate and to conform to the substrate. The layer of material is compatible for use with the resin. The first edge is disposed at the front of the surface relative to the movement of the pressure shoe to the fabric. The first edge is curved with a center portion of the first edge being relatively forward of a pair of side portions of the first edge.

Yet another embodiment of the present invention relates to a system for fabricating a composite item from a resin impregnated fabric placed on a layup form. The system includes a fabric lamination machine that includes an end effector. The fabric lamination machine moves the end effector along a natural path across the layup form. The end effector includes a supply reel and a pressure shoe. The supply reel retains a supply of the resin impregnated fabric. The resin impregnated fabric is withdrawn from the supply reel at a feed rate. The pressure shoe presses the resin impregnated fabric on to the layup form. The pressure shoe includes a surface having a layer of material and a first edge. The surface moves relative to the layup form and conforms to the layup form. The layer of material is compatible for use with the resin. The first edge is disposed at the front of the surface relative to the movement of the pressure shoe to the resin impregnated fabric. The first edge is curved with a center portion of the first edge being relatively forward of a pair of side portions of the first edge.

Yet another embodiment of the present invention pertains to an apparatus for fabricating a composite item from a material placed on a layup form. The apparatus includes a means for determining a first location on the layup form to place the material, a means for determining a second location on the layup form to stop placing the material, and a means for cutting the material to generate a first edge that substantially conforms to the layup form at the first location in response to the first edge being different from the layup form at the first location. In addition, the apparatus includes a means for tacking the first edge to the layup form at the first location and a means for applying the material along a natural path of the layup form between the first location and the second location. The material is urged outward from about a longitudinal centerline of the material by movement of a curved surface relative to the material. The apparatus further includes a means for cutting the material to generate a second edge that substantially conforms to the layup form at the second location in response to approaching the second location.

Yet another embodiment of the present invention relates to a method of fabricating a composite item from a material placed on a layup form. In this method, a first location is determined on the layup form to place the material, a second location is determined on the layup form to stop placing the material, and the material is cut to generate a first edge that substantially conforms to the layup form at the first location in response to the first edge being different from the layup form at the first location. In addition, the first edge is tacked to the layup form at the first location, the material is applied along a natural path of the layup form between the first location and the second location. The material is urged outward from about a longitudinal centerline of the material by movement of a curved surface relative to the material and the material is cut to generate a second edge that substantially conforms to the layup form at the second location in response to approaching the second location.

Yet another embodiment of the present invention pertains to a computer readable medium on which is embedded computer software comprising a set of instructions for executing a method of fabricating a composite item from a material placed on a layup form. In this method, a first location is determined on the layup form to place the material, a second location is determined on the layup form to stop placing the material, and the material is cut to generate a first edge that substantially conforms to the layup form at the first location in response to the first edge being different from the layup form at the first location. In addition, the first edge is tacked to the layup form at the first location, the material is applied along a natural path of the layup form between the first location and the second location. The material is urged outward from about a longitudinal centerline of the material by movement of a curved surface relative to the material and the material is cut to generate a second edge that substantially conforms to the layup form at the second location in response to approaching the second location.

DETAILED DESCRIPTION

The present invention provides, in some embodiments, a system for placing plies to generate a composite item and a method of using this system. In an embodiment, the invention provides for a numerically controlled (NC) automated fabric lamination machine (AFLM). This lamination device includes a positioning device to position an end effector. The positioning device includes any suitable device such as a gantry, robotic armature, wheeled or tracked vehicle, and/or the like. The end effector generally includes any device suitable to be positioned by the positioning device. For example, end effectors include milling, dispensing, and/or finishing heads or modules. In a particular example, the end effector includes a dispensing head to place plies, or resin impregnated fabric, upon a layup mold or tool. Typically, the ply material is slightly tacky and will adhere to the surface of the tool, or previously applied plies, in response to a sufficient amount of compressive force. To apply this force, the end effector includes a pressure shoe module. In addition, the end effector includes a cutting assembly having a rotating anvil to support cuts in the ply material.

The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout.FIG. 1is a perspective view of an automated fabric lamination machine (AFLM)10suitable for use with an embodiment of the invention. As shown inFIG. 1, the AFLM10includes a positioning device12to control the movement of an end effector14relative to a layup mold or tool16. In various forms, the positioning device12includes any suitable system to control the movement of the end effector14relative to the tool16. Examples of suitable systems include an armature type device as illustrated inFIG. 1, a gantry type device, and the like. In an embodiment of the invention, the positioning device12is configured to control twelve axes of movement (seven axes of the positioning device and five axes of the end effector14). However, it is to be understood that the specific number of axes may depend upon the particular operating condition and thus, the number of axes controlled is not critical to the invention.

FIGS. 2 and 3are perspective views of the end effector14. As shown inFIG. 2, a pre-impregnated fabric material (“prepreg”)18is stored on a supply roll20. As the prepreg18is dispensed from the supply roll20, a separator or backing film22is stripped away and accumulates on a backing take-up roll24. The prepreg18is conveyed to and wrapped partially around a vacuum cutting drum26or anvil. This cutting drum26includes a porous tube28of a material suitable for use as a knife cutting back-up surface. Examples of suitable materials include ultra high molecular weight (“UHMW”) polyethylene, Delrin®, nylon, acetal, and the like. A vacuum chamber30is disposed within the drum26and configured to draw air through the porous tube28. In this manner, the prepreg18is drawn toward the cutting drum26and essentially held in place along the outside of the tube28. In an embodiment, air is drawn through the cutting drum26at those locations covered by the prepreg18and is essentially sealed at those locations not covered by the prepreg18. In this manner, vacuum pressure is not wasted. In a specific example, the vacuum chamber30includes a seal S that directs the vacuum towards about half of the circumference of the cutting drum26.

The end effector14further includes one or more cutting assemblies32to cut the prepreg18. For example, the end effector14includes a pair of cutting assemblies32configured to cut the prepreg18held on the drum26. In general, the cutting assemblies32perform end cuts, such as leading edge and trailing edge cuts and/or perform cuts to generate side edge profiles. The cutting assemblies32include any suitable device operable to sever or otherwise cut the prepreg18. Suitable devices include ultrasonic knives, saws, lasers, and the like. Furthermore, the cutting assemblies32are configured to perform according to signals from a controlling device. In this regard, to generate edge profiles and diagonal cuts in the prepreg18, movement of the cutting drum26is controlled to coincide with movement of the cutting assemblies32. According to an embodiment, movement of the cutting drum26is utilized to orchestrate movements of the various other components of the AFLM10. For example, in response to the cutting drum26being controlled to advance the prepreg18through the end effector14, the supply roll20is controlled to dispense prepreg18and the positioning device12is controlled to advance the end effector14along the tool16.

According to an embodiment and as illustrated inFIGS. 2 and 3, the cutting assemblies32are offset with regard to their respective positions along the cutting drum26. In this manner, each of the cutting assemblies32are configured to cut across the full width of the prepreg18or any portion thereof without interfering with the action of the one or more other cutting assembly32. It is an advantage of the offset in the cutting assemblies32that while one cutting assembly32is cutting a profile of the prepreg18, another cutting assembly32may perform an end cut.

The end effector14further includes a pressure shoe34and pressure shoe module36. At the beginning of each laydown run, the pressure shoe module36is configured to transfer the prepreg18from the drum26and apply the material on to the tool16. For example, in response to a leading edge of the prepreg18reaching an appropriate position along the drum26, the prepreg18is detachably secured to the pressure shoe34. As shown inFIG. 3, the pressure shoe module36is configured to control the movement of the pressure shoe34from a ‘transfer’ position shown inFIG. 2to a ‘laydown’ position shown inFIG. 3. As the pressure shoe34is moved in this manner, additional prepreg18is fed and processed through the end effector14to provide sufficient slack and form a “loop” of the prepreg18ahead of the pressure shoe34.

In addition, excess prepreg18beyond the edge profile cut by the cutting assemblies32is accumulated on a take-up roll38. In an embodiment, some portion of each side edge of the prepreg18is left uncut. In this manner, a continuous strip of prepreg18is generated that facilitates collection of the prepreg18.

In an embodiment, the pressure shoe module36includes a plurality of linkages40. These linkages40are configured to facilitate movement of the pressure shoe34along the paths42indicated by the dashed lines shown inFIG. 3. In conjunction with the movement of the pressure shoe module36, various other components of the AFLM10are synchronized during transfer. That is the prepreg18being dispensed by the vacuum cutting drum26and the edges profiled by the cutting assemblies32are controlled in such a manner so as to maintain the positional integrity of the prepreg18relative to the pressure shoe34. In other words, sufficient prepreg18is dispensed during the transfer that tension does not build up and cause the prepreg18to slide on the pressure shoe34. In this manner, the cut edges may be accurately placed upon the tool16. It is an advantage of this embodiment that the pressure shoe34initially moves away from the drum26in an essentially tangent manner. That is, relatively little torque is initially applied to the prepreg18. Once sufficient slack has accumulated between the vacuum cutting drum26and the pressure shoe34, the pressure shoe module36is controlled to orient the pressure shoe34and attached prepreg18into the laydown position as illustrated inFIG. 3. According to other embodiments, the pressure shoe module36is controlled to move in a similar manner utilizing other suitable devices. For example, the pressure shoe module36is configured to follow a race or other such channel that conforms to the path42. In another example, a numerically controlled armature is configured to control the pressure shoe module36along the path42.

FIG. 4is a perspective view of the pressure shoe34and pressure shoe module36according to an embodiment shown inFIG. 1. As shown inFIG. 4, the pressure shoe34includes a contact surface44, conforming material46, and vacuum ports48. The contact surface44includes a flexible material suitable for use with the resin impregnated prepreg18. Examples of suitable materials include polyethylene polymers, UHMW polyethylene, Delrin®, nylon, acetal, and the like. In addition, the contact surface44includes a curved forward edge50. It is an advantage of embodiments of the invention that the curved forward edge50facilitates an outward spreading of the prepreg18as the prepreg18is being applied to the tool16. This outward spreading reduces a tendency of the prepreg18to “wrinkle” when applied to a curved tool16. To explain, when a fabric is draped over a double convex male surface such as a dome, excess fabric accumulates along the edge. If this excess fabric is not dealt with, wrinkles will result. By pulling or stretching the fabric along the edges or at the corners of the fabric and in line with the direction the fabric is being placed, the excess fabric is displaced. This “stretching” causes the angle between longitudinal and crosswise (warp and fill) yarns to deviate from 90 degrees in some areas, but the length of each individual yarn remains essentially constant. This change in angle between warp and fill fibers is called “trellising.”

The conforming material46includes a foam or other such compressible and resilient material that provides support for the contact surface44and facilitates conformation of the contact surface44to a contour of the tool16. More particularly, the conforming material46facilitates conformation to positive and negative radius contours that are in line with the contact surface44, perpendicular to the contact surface44, and/or at an oblique angle to the contact surface44. The amount of curvature the conforming material46is able to accommodate is dependent upon a variety of factors, such as, for example: length, width, thickness, compressibility, and resilience of the conforming material46.

In an embodiment, the vacuum ports48are disposed in close proximity to a trailing edge52of the contact surface44. The vacuum ports48are in fluid connection to a vacuum source such as, for example a vacuum pump, vacuum producing venturi, and/or the like. For example, as illustrated inFIG. 4, each vacuum port48is connected to a respective vacuum hose54, which in turn, is connected to a vacuum manifold56. The vacuum manifold56is in fluid connection to a vacuum producing venturi58that is powered via a pressure hose60that supplies compressed air. To decrease the radius of curvature of the vacuum hoses54and thereby decrease the tendency of the vacuum hoses54to “kink”, the vacuum hoses54are routed to vacuum ports48as illustrated inFIG. 4. It is an advantage of such a routing scheme that by routing the vacuum hoses54that supply vacuum to the more centrally located vacuum ports48to the vacuum manifold relatively closer (proximal) to the vacuum source than the relatively distal vacuum ports48the vacuum force of the vacuum ports48that are relatively centered upon the contact surface44are increased.

In various other embodiments, the vacuum ports48are disposed about the middle and/or curved forward edge50of the contact surface44. In addition, although the vacuum ports48are illustrated inFIG. 4as being substantially uniform in size and spaced substantially evenly along the trailing edge52, in other embodiments, the spacing and/or port diameter is heterogeneous. For example, to increase vacuum holding potential near the center of the contact surface44, the vacuum ports48are disposed more densely towards the center of the contact surface44. Furthermore, the vacuum ports48need not be holes, but rather, include porous or permeable material.

In addition to the vacuum manifold56and vacuum producing venturi58, the pressure shoe module36includes a spring62, actuator64, and attachment flanges66. The spring62, or platen, supports the contact surface44and is configured to conform to a contour in the tool16. In this regard, the conforming material46facilitates conformation to relatively small contours in the tool while the spring62facilitates conformation to relatively large contours in the tool. To facilitate these relatively large contours, the spring62includes a sheet of resilient material such as metals, plastics, composites, and/or the like. In a particular example, the spring62includes a sheet of fiberglass that, as shown inFIG. 4, is supported at both ends and configured to flex. To generate a substantially uniform amount of downward pressure across the length of the spring62, the cross-section of the spring62is varied across the length. The amount of curvature the spring62is able to accommodate is dependent upon a variety of factors, such as, for example: length, width, thickness, and resilience of the spring62. For example, in an embodiment, the spring62is configured to facilitate conformation to contours having a positive radius of about 20 inches or greater.

The actuator64applies torque to the linkages40in response to controlling signals. In this manner, the pressure shoe module36is moved between the transfer and laydown positions. The attachment flanges66provide fastening points to attach the pressure shoe module36to the end effector14. In addition, the pressure shoe module36optionally includes a respective exhaust muffler68for each of the vacuum producing venturis58to lessen noise produced therein.

FIG. 5is a perspective view of the end effector14according to an embodiment shown inFIG. 1. As shown inFIG. 5, end effector14includes a housing or frame70to attach and support the various components of the end effector14. The frame70includes a mounting plate72to secure the end effector14to the positioning device12. Additionally shown inFIG. 5is a plurality of actuators74-80configured to respectively control the rotational movement of the supply roll20, backing take-up roll24, vacuum cutting drum26, and take-up roll38. Further illustrated inFIG. 5is a hub82, vacuum hose84, and vacuum producing device86such as a vacuum pump, turbine, and/or venturi/muffler.

FIG. 6is a block diagram of a system90suitable for use with the AFLM10. As shown inFIG. 6, the system90includes a controller92. The controller92is operable to execute computer readable code. In this regard, the system90includes a set of computer readable instructions or code94. According to the code94, the controller92is configured to access a file96. This file96includes one or more of the following: a computer readable model of the composite item; a computer readable representation of the surface of the layup form or the tool16; a computer readable representation of the edges of the tool16; the thickness of the composite item; a source code based upon at least one of the composite item and the tool16; a set of movement instructions based upon the source code; data gathered while laying up the composite item; timestamp information; positional information; identification numbers; and the like. The controller92is further configured to communicate across a network98. The network98is optionally included to provide additional data storage and/or processing capabilities. In this regard, the network includes a database100and a server102. The database100is configured to store a copy of the code94and/or file96. The server102is configured to generate, store, and perform any suitable processing of the code94and/or file96. In this manner, composite items generated on computer aided design (CAD) machines such as the server102, for example, may be forwarded to the AFLM10. In addition, the server102is operable, via the network98, to forward updates for the code94and/or file94. In addition, the system90optionally includes a memory104. If present, the memory104is configured to store a copy of the code94and/or file96.

Also shown inFIG. 6is a positioning device controller106. The positioning device controller106is optionally included in the system90depending upon the requirements of the various actuators and/or servo motors of the AFLM10. That is, depending upon the particular configuration of the AFLM10, a plurality of actuators and/or servo motors modulate the rotation, position, speed, direction, and the like of the various components of the AFLM10. More particularly, these actuators and/or servo motors of the positioning device are at least configured to modulate the various axes of the end effector14and/or AFLM10. If present, parameters of the positioning device controller106are based upon the specification of the various actuators, servos, and/or the controller92. The positioning device controller106, if present, is configured to control some or all of these actuators and/or servo motors. In addition, these actuators and/or servo motors are optionally operable to be modulated by the controller92directly, and thus, the system90may not include the positioning device controller106.

In addition, the controller92is configured to modulate any suitable actuator and/or servo motor, such as the actuators64and74-80and the cutting assemblies32for example, and thereby control the various components of the AFLM10. In this manner, the controller92is configured to control the movement of the prepreg18through the end effector14. In this regard, the actuators74-80are configured to modulate the position, speed, direction, tension, and the like of the prepreg18and the separator film. Furthermore, the controller92is configured to modulate the actuator64and thereby control the pressure shoe module36.

The system90further includes a plurality of sensors configured to sense the various operating conditions of the AFLM10. More particularly, the system90optionally includes sensors to sense any suitable attribute of the AFLM10. Examples of suitable attributes include some or all of the temperature of the prepreg18, the temperature at the location where the separator film22is separated from the prepreg18(release point), feed rate and direction, material placement, backing integrity, supply of prepreg18, prepreg18tension between the supply roll20and the vacuum cutting drum26, prepreg18tension between the vacuum cutting drum26and take-up roll38, and/or the like.

To apply a tackifier to the tool16, the system90optionally includes a tackifier applicator108. The tackifier facilitates first ply adhesion to the tool16. More particularly, tackifier resins modify the Theological properties of an adhesive system. These tackifiers are combined with base polymers/elastomers in adhesives to improve the tack or ability to stick. In general this property is achieved by an increased wetting out onto a surface and improved specific adhesion. More specifically, by modulating the tackifier and base resin combination, the viscoelastic behavior of the adhesive is varied. In addition, the particular tackifier utilized is typically dependent upon its suitability or compatibility with the base resin. For example, suitable tackifiers for use with a bismaleimide (BMI) resin base may include: Toray E-09 manufactured by Toray Composites (America) of Tacoma, Wash.; MSR 355-HSC manufactured by The Boeing Company of Chicago, Ill.; and the like. The invention is not limited to the use of BMI resin and its compatible tackifiers, but rather, any suitable resin and base/tackifier resin system is within the scope of embodiments of the invention. However, tackifier may tend to foul the contact surface44. As the width of the prepreg18is modulated by the cutting assemblies32, so to is the width of the tackifier application modulated. In this regard, the tackifier applicator108applies the tackifier in a controllable manner. In an embodiment, the tackifier applicator108is modulated by the controller92to apply the tackifier to the tool16in an area where the prepreg18is to be placed substantially without overlap into adjacent areas. For example, the tackifier applicator108includes an array of independently controllable spray nozzles that essentially span the width of the prepreg18. In another example, the tackifier applicator108includes a spray nozzle that is controllable to sweep to and fro and thereby span the width of the prepreg18or some portion thereof.

To evaporate the tackifier (“flash off”), modulate the temperature of the tool16, the prepreg18and/or the separator film22, the system90optionally includes a heater110. The heater110includes any suitable heating device such as, for example an electrical heating element and blower, infrared device, induction heater, and/or the like. In a particular example, the heater110includes a heating element and a blower configured to direct a stream of heated air as appropriate. For example, the stream of heated air may be directed aft of the tackifier applicator108and forward of the pressure shoe module36. In addition, the heater110optionally includes a nib heater, chute heater, and release point blower. If present, these devices are modulated by the controller92. The nib heater applies a controlled amount of heat to the tool16, the prepreg18and/or the separator film22in response to controlling signals generated by the controller92. Similarly, the chute heater applies a controlled amount of heat to the prepreg18and/or the separator film22in response to controlling signals generated by the controller92. In addition, the release point blower directs a flow of air toward the release point in response to controlling signals generated by the controller92.

FIG. 7is a system architecture for the controller92suitable for use in the system90. As shown inFIG. 7, the controller92includes a processor116. This processor116is operably connected to a power supply118, memory120, clock122, analog to digital converter (A/D)124, and an input/output (I/O) port126. The I/O port126is configured to receive signals from any suitably attached electronic device and forward these signals to the A/D124and/or the processor116. If the signals are in analog format, the signals may proceed via the A/D124. In this regard, the A/D124is configured to receive analog format signals and convert these signals into corresponding digital format signals. Conversely, the A/D124is configured to receive digital format signals from the processor116, convert these signals to analog format, and forward the analog signals to the I/O port126. In this manner, electronic devices configured to receive analog signals may intercommunicate with the processor116.

The processor116is configured to receive and transmit signals to and from the A/D124and/or the I/O port126. The processor116is further configured to receive time signals from the clock122. In addition, the processor116is configured to store and retrieve electronic data to and from the memory120. Furthermore, the processor116is configured to determine signals operable to modulate the positioning device controller106and thereby control the various actuators and/or servo motors of the AFLM10to exert a particular force and/or rotate to a particular degree. For example, signals associated with rotating the actuator78in a clockwise direction may be forwarded to the actuator78by the processor116via the I/O port126and thereby control the prepreg18to advance.

According to an embodiment of the invention, the processor116is configured to execute the code94. Based on this set of instructions and signals from the various components of the AFLM10, the processor116is configured to: determine a set of movement instructions; modulate the heater110, tackifier applicator108, cutting assemblies32, and the like.

FIG. 8illustrates steps involved in a method130of placing plies to produce a composite structure or product. Prior to the initiation of the method130, a composite product is designed and, based on this design, a series of computer readable instructions specifying attributes of the composite product is generated. These instructions are utilized to control the operations of the AFLM10. In addition, a form such as the tool16is designed and constructed based upon the design of the composite product. Furthermore, the supply roll20is installed in the end effector14and the prepreg18is threaded through the end effector14as shown and described herein.

At step132, the method130is initiated by turning on the various components of the AFLM10described herein above and executing the computer readable instructions.

At step134, the prepreg18is modulated by the action of the supply roll20, backing take-up roll24, vacuum cutting drum26, and/or the take-up roll38. For example, in response to the end of the prepreg18differing from the edge of the tool16, the vacuum cutting drum26is controlled to rotate and thereby advance or retreat the prepreg18until the prepreg18is in position to be cut by the cutting assemblies32. It is to be noted that in an embodiment, the prepreg18is essentially always cut along one or both edges (profiles) and that the step134is optionally performed to position the prepreg18for a leading edge cut. It is an advantage of this embodiment that a substantially continuous band of edge material is maintained throughout the layup procedure to aid in handling the prepreg18.

At step136, instructions from the file96are utilized for cutting an appropriate leading edge and/or profile for the prepreg18at the start of a course. In response to the instructions, the cutting assemblies32cut the leading edge and/or profile. In addition, profile and diagonal cuts are performed in conjunction with rotation of the vacuum cutting drum26. In this regard, cutting operations and feeding/movement operations are generally performed concurrently. Following the cuts, the prepreg18is advanced to a position at which the prepreg18is removed from the vacuum cutting drum26by the pressure shoe module36. That is, when the leading edge is cut, its position upon the vacuum cutting drum26is known. The vacuum cutting drum26is advanced until the position of the leading edge is located appropriately relative to the pressure shoe module36. As the prepreg18is further advanced and the pressure shoe module36is controlled to move in the lay down position, the prepreg18is preferentially drawn from the vacuum cutting drum26and remains attached to the contact surface44via the action of the vacuum from the vacuum ports48. In addition, while the prepreg18is being advanced, edge profile cuts based on the file96are performed on the prepreg18by the cutting assemblies32.

If tackifier is to be applied to the tool16, the tackifier applicator108is controlled to do so and the heater110is optionally controlled to flash off at least a portion of a solvent in the tackifier. As described herein, the tackifier is applied in a controlled manner according to instructions in the file96. In this manner, there is essentially no excess tackifier applied that might otherwise negatively impact the performance of the pressure shoe module36.

At step138, the prepreg18is “tacked” to a substrate. The substrate includes, at least, the tool16and/or a previously applied course of the prepreg18. For example, the pressure shoe module36is controlled to move into the lay down position and further positioned relative to the tool16via the action of the positioning device12. A downward force is applied to the pressure shoe module36, pressing the prepreg18down upon the tool16with sufficient force to cause adhesion. In addition, the location on the tool16is determined based upon the series of computer readable instruction and/or the location of a previously positioned prepreg18.

At step140, the prepreg18is dispensed along a path across the tool16. In order to minimize deformations in the prepreg18(e.g., wrinkles), this path is typically calculated to coincide with a “natural path” based upon any contours in the tool16. As the end effector14is controlled along the path across the tool16, the prepreg18is advanced via the action of the supply roll20, backing take-up roll24, vacuum cutting drum26, and take-up roll38and edge profiles of the prepreg18are cut via the action of the cutting assemblies32. As the prepreg18is being dispensed or applied to the tool16, the curved leading edge of the contact surface44urges the prepreg18outward from approximately a longitudinal center line of the prepreg18. It is an advantage of an embodiment that this outward urging “forms,” trellises, or alters the angle between the warp and the weft of the prepreg18over contours in the tool16and thereby reduces wrinkles or bridges in the prepreg18.

At step142, the placement of the prepreg18on the tool16is evaluated. For example, an operator or a sensor may sense the relative position of the prepreg18and a previously positioned prepreg18and determine if the distance between these plies is within a predetermined tolerance. If the distance between these plies is not within the predetermined tolerance, an error may be generated at step144. If the distance between these plies is within the predetermined tolerance, it is determined if the end of the path has been reached at step148. In addition to placement of the prepreg18, wrinkles, bridges, foreign objects, debris, and the like are optionally sensed for by an operator and/or sensor. If any such abnormalcy is sensed, an error is generated.

At step148, it is determined if the end of the course has been reached. More specifically, it is determined if the prepreg18that is approaching the cutting assemblies32is to be end cut. If, based on the series of computer readable instruction, it is determined the prepreg18has not advanced to the end of the course, additional prepreg18is dispensed at step140. If, it is determined the prepreg18has advanced to the end of the course, the prepreg18is end cut at step150.

At step150, the end of the prepreg18is cut based upon the series of computer readable instruction contained in the file96, the orientation of a previously positioned prepreg18, and/or the location of a previously positioned prepreg18. In addition, to reduce the likelihood that the prepreg18adheres to the contact surface44, the pressure shoe module36is controlled to maintain a forward movement with respect to the tool16as the end of the prepreg18is applied to the tool16. That is, rather than coming to a stop at the end of the path, the positioning device12controls the end effector14to advance past the end of the path and the pressure shoe module36is optionally controlled to lift off the surface of the tool16as it is advanced past the end of the prepreg18.

In an embodiment, to perform the trailing edge cut and maintain forward movement of the end effector14, the end effector14is controlled to advance a sufficient excess of the prepreg18to complete the cut without stoppage of the end effector14. For trailing edge cuts other than 90° “butt cuts”, little or no excess prepreg18may be required as the cutting assembly32may be sufficiently fast to perform the cut while the prepreg18is in motion. Cuts at about 90° are generally performed while the vacuum cutting drum26is essentially stationary. However, by generating excess prepreg18between the vacuum cutting drum26and the pressure shoe module36, the vacuum cutting drum26may be held in a stationary manner until the cut is completed while the end effector14maintains forward progress. In this regard, some amount of slack or buffer of the prepreg18is generally maintained between the vacuum cutting drum26and the pressure shoe module36as a normal course to reduce tension and thereby facilitate trellising of the prepreg18. In addition, to further facilitate cutting operations described herein, a third cutting assembly32may be included in the end effector14.

At step152, it is determined if the placement of prepreg18on the composite product has been completed. For example, if all of the computer readable instructions in the file96have been completed, it may be determined that the placement of plies for the composite product has been completed and the AFLM10may idle until another series of computer readable instructions is initiated. If is determined the placement of prepreg18for the composite product is not completed, an additional prepreg18placement may proceed at step134.

Following the method130, the composite product may be cured in any suitable manner. In the aerospace industry, thermoset resins are generally utilized to pre-impregnate ply material. These thermoset resins are typically cured by being held at an elevated temperature for a predetermined amount of time. Times and temperatures may be selected depending on the resin used, the size and thickness of the composite product, and the like. An advantage of at least some embodiments of the invention is that the spreading and smoothing capabilities of the contact surface44allows for the use of relatively wider prepreg18. In particular, the use of wider prepreg18while generating contoured composite products is enhanced. In known ply placement systems, wider ply stock tends to wrinkle when applied to contours.

Although an example of the end effector14is shown being controlled by the positioning device12, it will be appreciated that other control systems can be used. In this regard, a gantry system or other such known positioning devices that support and control the movement of any suitable end effector are suitable for use with end effector14which incorporates the pressure shoe module36. Also, although the AFLM10is useful to place plies for composite products in the airline industry it can also be used in other industries that construct composite product. These industries include, but are not limited to, automobile, marine, spacecraft, building, and consumer products.