Fiber placement head with enhanced restart

Abstract

A fiber placement head for applying a plurality of composite tape segments to a mold, the fiber placement head including: a pre-start lane assembly having a pre-start power roller that moves the composite tape segments from a composite tape supply; a restart lane assembly having a restart power roller that also moves the composite tape segments from the composite tape supply; and a cutting lane assembly having a reciprocating cutting blade, wherein the pre-start power roller draws the composite tape from the composite tape supply and the restart power roller positions the composite tape segments on the mold.

Description

[Technical field]

[0001] This application relates to fiber placement machines and, more particularly, to fiber placement heads. [Background technology]

[0002] Fiber placement machines are used to create composite workpieces. Composite material or tape in the form of resin-impregnated fibrous material is mechanically applied to a mold or mandrel in precise locations and lengths to collectively form the composite workpiece. The fiber placement machine moves a fiber placement head over the mold to precisely apply the composite tape to the final shape of the composite workpiece. As the fiber placement head moves, it leaves multiple composite tape segments, also called courses or tows, on the mold. Multiple composite tape segments may be applied simultaneously as part of a course, but the fiber placement head can control each of the tows individually as part of applying the course. The automated application of these composite tape segments to the mold involves the cooperation of a diverse array of machines that hold, move, and ultimately cut the composite tape. Summary of the Invention [Problem to be solved by the invention]

[0003]

[0003] A fiber placement head may include cutting, clamping, and moving elements that draw the composite tape from a supply, segment each lane of the composite tape, and apply the composite tape segments to the mold. As the speed at which the fiber placement head applies the composite tape segments increases, the challenge of coordinating with sufficient precision the cutting, clamping, and moving of the composite tape through the head and to the mold also increases. [Means for solving the problem]

[0004]

[0004] In one embodiment, a fiber placement head for applying multiple composite tape segments to a mold includes a pre-start lane assembly having a pre-start power roller that moves the composite tape segments from a composite tape supply, a restart lane assembly having a restart power roller that also moves the composite tape segments from the composite tape supply, and a cutting lane assembly having a reciprocating cutting blade, wherein the pre-start power roller draws the composite tape from the composite tape supply and the restart power roller positions the composite tape segment on the mold.

[0005]

[0005] In one embodiment, a fiber placement head for applying a plurality of composite tape segments to a mold includes a pre-start lane assembly having a pre-start power roller for moving a composite tape segment from a composite tape supply source, a restart lane assembly having a restart power roller for similarly moving the composite tape segment from the composite tape supply source, and a cutting lane assembly having a reciprocating cutting blade, wherein the pre-start power roller draws the composite tape from the composite tape supply and reduces the amount of tension between the pre-start power motor and the restart power motor as the restart power roller positions the composite tape segment on the mold. [Brief description of the drawings]

[0006] [Figure 1] 1 is a perspective view of one embodiment of a fiber placement machine. [Diagram 2]

[0007] FIG. 2 is another perspective view of an embodiment of a fiber placement head. [Diagram 3]

[0008] FIG. 2 is a perspective view of one embodiment of a portion of a fiber placement head. [Figure 4]

[0009] FIG. 2 is another perspective view of an embodiment of a portion of a fiber placement head. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007]

[0010] A fiber placement machine may use a robotic arm carrying a fiber placement head with a cut, clamp, and restart (CCR) assembly. The CCR assembly includes a plurality of cut lane assemblies, clamp lane assemblies, restart lane assemblies, and pre-start lane assemblies, each of which may be removably coupled to the fiber placement head. Each lane assembly may be designed to process one or more strands of composite tape passing through it. The pre-start and restart lane assemblies may cooperate to pull the composite tape from a fiber source and move the tape to a mold.

[0008]

[0011] Previous fiber placement heads have lacked a pre-start lane assembly, and instead rely solely on the restart lane assembly and its driven rollers to both pull the fiber from a composite tape source, such as a spool, and deliver the composite tape to the mold. The use of a restart lane assembly to both remove the composite tape from the composite tape source and to feed the composite tape so that it can be positioned on the mold at faster layup speeds (e.g., >900 in / min), can increase tension on the composite tape as it is pulled from the composite tape source. For example, at faster layup speeds, the pinch lane assembly can hold a composite tape segment and then suddenly release the segment. The release of the composite tape segment can impose a momentary spike in tension on the composite tape segment as the pinch lane assembly releases the tape and the restart lane assembly accelerates the composite tape segment into the mold. Tension spikes can cause the composite tape segment to shift or slip relative to the restart roller, resulting in positional inaccuracies as the tape segment is applied to the mold.

[0009]

[0012] Including a pre-start lane assembly in addition to a restart lane assembly in the fiber placement head can avoid momentary spikes in tension on the composite tape to pull the composite tape from the composite tape source and accurately position the composite tape segment on the mold. For example, the pre-start assembly can include power rollers and pinch rollers that are positioned proximate to the composite tape source and collectively responsible for drawing the composite tape from the source. The performance of the pre-start assembly can be designed to pull the composite tape from the composite tape source and deliver it toward the pinch lane assembly and restart lane assembly. The restart lane assembly can include power rollers and pinch rollers and can be primarily responsible for positioning the composite tape on the mold. The restart lane assembly and the pre-start lane assembly can cooperate to introduce some slack in the composite tape between them. For example, the pre-start lane assembly can operate its power rollers at a slightly faster angular velocity than the power rollers of the restart lane assembly. This can reduce or eliminate tension on the composite tape segment downstream of the pre-start lane assembly and can also help the restart lane assembly to more accurately position the composite tape segment on the mold.

[0010]

[0013] One embodiment of a fiber placement machine 10 is shown in FIG. 1. The fiber placement machine 10 includes a robot arm 12 detachably coupled to a fiber placement head 14. The robot arm may be supported by a base 16 on which the robot arm moves linearly about an axis (x). A number of movable segments 18 may extend outwardly from the base 16, which may move, for example, by pivoting, rotating, or telescoping. The robot arm 12 may move about a number of axes relative to the base 16. For example, a first segment 18a may be rotatably coupled to the base 16 at one end such that the robot arm 12 may rotate about the base 16. A second segment 18b may be pivotally coupled to the first segment 18a, and a third segment 18c may be pivotally coupled to the second segment. A fourth segment 18d may be coupled to the third segment 18c and telescopically move away from and toward the third segment 18. The segments 18 may be moved relative to one another using a fluidic ram, an electric motor, or a combination thereof, or other drive elements to move the distal end of the robot arm 12 relative to a mold 20 or mandrel used to create a workpiece.

[0011]

[0014] A microprocessor (not shown) in communication with a computer readable storage medium having executable instructions may control the movement of the fluid ram, electric motor, or other drive elements, thereby controlling the motion and position of the moveable segment 18 of the robot arm 12. The microprocessor may be any type of device capable of processing electronic instructions, including microcontrollers, host processors, controllers, and application specific integrated circuits (ASICs). The microprocessor may be a dedicated processor used solely to provide control of the robot arm 12, or may be shared with other machine functions. The microprocessor executes various types of digitally recorded instructions, such as software or firmware programs stored in memory. Communication between the microprocessor and mechanisms, such as the fluid ram or electric motor, that move the robot arm may occur via a communication bus. The robot arm 12 may move the fiber placement head 14 along three axes to position the head 14 for servicing or to apply composite tape to the mold 20. This is one embodiment of a robot arm 12 that may be used with a fiber placement head, although other embodiments of robot arms or mechanical devices that apply composite tape may be used as well.

[0012]

[0015] The end of the robotic arm 12 distal to the base 16 can include a chuck 22 that releasably engages the fiber placement head 14. The chuck 22 and a portion of the fiber placement head 14 can have corresponding features such that the chuck 22 can releasably grip the fiber placement head 14. In one embodiment, the fiber placement head 14 includes a cylindrical shank that extends perpendicular to a surface of the head 14. The robotic arm 12 can position the chuck 22 such that the chuck 22 engages the shank and the fiber placement head 14 is resiliently coupled to the arm 12.

[0013]

[0016] As shown in FIGS. 2-4, the fiber placement head 14 may include a creel 24 including multiple spools 26 that store composite tape as a supply of composite tape for the head 14, and a cut-clip-and-restart (CCR) assembly 32. The CCR assembly 32 may include a compression roller 34 that may receive the composite tape from the spools 26 and apply it to the mold 20 to create a composite part. The creel frame 24 includes multiple exterior surfaces 36 and a spindle 38 mounted perpendicular to the exterior surfaces 36. The spindle 38 may be moved to generate tape tension using a pneumatically, mechanically, or fluidically controlled dancer element that helps maintain tension on the composite tape as the tape is applied to the mold 20. The composite tape may be unwound from the spools 26 and moved to the compression roller 34 for final application to the mold 20.

[0014]

[0017] The fiber placement head 14 may include a CCR frame 40 for supporting the components of the fiber placement head 14, the CCR assembly 32, and the compression roller 34 that ultimately presses the continuous stream of composite tape segments against the mold 20. Before reaching the compression roller 34, a portion of the composite tape may pass through an upper feed section 42 and another portion of the composite tape may pass through a lower feed section 44. The upper feed section 42 may process the even numbered composite tapes and the lower feed section 44 may process the odd numbered composite tapes that meet at the compression roller 34. As an example, for a fiber placement head 14 having eight fiber paths or lanes, the upper feed section 42 may process the composite tapes identified by numbers 2, 4, 6, and 8, while the lower feed section 44 may process the composite tapes identified by numbers 1, 3, 5, and 7. The upper feed section 42 and the lower feed section 44 may be separated by an angle (α). Upper and lower feed rollers 46, 48 may help direct the composite tape from the spool 26 to the upper and lower feed sections 42, 44, respectively. A plurality of lane assemblies 54 may be included in the upper and lower feed sections 42, 44. Each of the upper and lower feed sections 42, 44 may include a manifold for actuating the moving parts of the lane assemblies 54. An electromechanical valve may abut the lane assemblies 54 to selectively supply compressed air to the assemblies 54 for actuation. In one embodiment, the solenoid valve includes a solenoid that receives a voltage controlled by a switch that a microprocessor opens and closes to control actuation of the lane assemblies 54.

[0015]

[0018] The lane assemblies 54 include a pre-start lane assembly 54a, a nip lane assembly 54b, a restart lane assembly 54c, and a cut lane assembly 54d, which are carried by the CCR frame 40. The lane assemblies 54 collectively pull the composite tape from the spool 26 and apply the tape to the mold 20. The pre-start lane assembly 54a may include a pre-start power roller 56 and a pre-start pinch roller 58, respectively, that initially pull the composite tape 60 from the spool 26. The pre-start power roller 56 may be rotated by an electric motor and may include a motor encoder that sends a signal to the microprocessor indicative of the position of the composite tape 60. The microprocessor may also control the current supplied to the electric motor that drives the pre-start power roller 58. The pre-start motive roller 56 and the pre-start pinch roller 58 may be moved to releasably engage opposite sides of the composite tape 60 and rotate in opposite rotational directions to pull the composite tape 60 towards the other lane assembly 54. In one embodiment, the pre-start motive roller 56 and the pre-start pinch roller 58 may be moved closer to or farther from the composite tape 60 using compressed air. The composite tape 60 may then pass through the nip lane assembly 54b. The nip lane assembly 54b may include nip rollers 62 positioned on opposite sides of the composite tape 60 that releasably engage the tape and hold it in a fixed position for a short period of time. The nip rollers 62 may be moved closer to or farther from the composite tape and held to prevent the rollers 62 from rotating to prevent the tape from moving.

[0016]

[0019] The composite tape 60 may then pass through a restart assembly 54c, which may include a restart power roller 64 and a restart pinch roller 66. The restart assembly 54c may be responsible for precisely positioning the segment of the composite tape 60 on the former 20. The restart power roller 64 may be rotated by an electric motor and may include a motor encoder that may send a signal to a microprocessor (not shown) indicative of the position of the composite tape 60. The microprocessor may also control the electric motor that drives the restart power roller 64 in a manner similar to that described above for the pre-start power roller 56. The restart power roller 64 and the restart pinch roller 66 may be moved to engage opposite sides of the composite tape 60 and rotate in opposite rotational directions to precisely position the segment of the composite tape 60 on the former 20. The pre-start motive roller 58 can be controlled to rotate at an angular velocity greater than the angular velocity at which the restart motive roller 64 rotates for a predetermined period of time such that tension on the composite tape 60 between the motive rollers 58, 64 is reduced or completely removed so that slack exists and the composite tape 60 is not under tension. In another embodiment, the pre-start motive roller 58 can be operated at the same angular velocity as the restart motive roller 64. The restart assembly 54c can then very precisely lay out a segment of the composite tape 60 on the mold 20 without interference of increased composite tape tension. The cutting lane assembly 54d can include a reciprocating cutting blade 68 to selectively cut the composite tape 60 to produce a predetermined length of composite tape 60 that is applied to the mold 20 and is part of the workpiece.

[0017]

[0020] It should be understood that the foregoing is a description of one or more embodiments of the present invention. The present invention is not limited to the specific embodiments disclosed herein, but rather is defined solely by the following claims. Furthermore, the statements contained in the above description are of specific embodiments and should not be construed as limitations on the scope of the present invention or on the definition of the terms used in the claims, unless the terms or phrases are expressly defined above. Various other embodiments, as well as various changes and modifications to the disclosed embodiments, will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to be included within the scope of the appended claims.

[0018]

[0021] In this specification and claims, the terms "eg," "for example," "for instance," "such as," and "like," as well as the verbs "comprising," "having," "including," and other verb forms thereof, when used in conjunction with a list of one or more components or other items, should each be construed as open-ended, that is, the list should not be considered to exclude other additional components or items. Other terms should be construed using the broadest reasonable meaning of those terms, unless those terms are used in a context that requires a different interpretation.

Claims

1. A fiber placement head for applying a plurality of composite material tape segments to a mold, a pre-start lane assembly having a pre-start power roller for moving the composite material tape segment from a composite material tape supply source, a restart lane assembly having a restart power roller for similarly moving the composite material tape segment from the composite material tape supply source, a cutting lane assembly having a reciprocating cutting blade, comprising, wherein the pre-start power roller pulls out the composite material tape from the composite material tape supply source, and the restart power roller positions the composite material tape segment on the mold, the pre-start power roller operates at an angular velocity greater than the angular velocity of the restart power roller, thereby reducing the amount of tension applied to the composite material tape segment between the pre-start power roller and the restart power roller, a fiber placement head.

2. The fiber placement head according to claim 1, wherein the amount of the tension is zero.

3. The fiber placement head according to claim 1, which moves the composite material tape at a layup speed of 22.86 m (900 inches) or more per minute.

4. The fiber placement head according to claim 1, further comprising a pre-start pinch roller releasably engaged with the pre-start power roller to hold the composite material tape segment.

5. The fiber placement head according to claim 1, further comprising a restart pinch roller releasably engaged with the restart power roller to hold the composite material tape segment.

6. A fiber placement head for applying a plurality of composite material tape segments to a mold, a pre-start lane assembly having a pre-start power roller for moving the composite material tape segment from a composite material tape supply source, a restart lane assembly having a restart power roller for similarly moving the composite material tape segment from the composite material tape supply source, a cutting lane assembly having a reciprocating cutting blade, comprising, wherein when the pre-start power roller pulls out the composite material tape from the composite material tape supply source and the restart power roller positions the composite material tape segment on the mold, the amount of tension between the pre-start power motor and the restart power motor is reduced, the pre-start power roller operates at an angular velocity greater than the angular velocity of the restart power roller, thereby reducing the amount of tension applied to the composite material tape segment between the pre-start power roller and the restart power roller, a fiber placement head.

7. The fiber placement head according to claim 6, wherein the amount of the tension is zero. **Claim 8** The fiber placement head according to claim 6, which moves the composite material tape at a laying-up speed of 22.86 m (900 inches) or more per minute. **Claim 9** The fiber placement head according to claim 6, further comprising a pre-start pinch roller that releasably engages with the pre-start power roller to hold the composite material tape segment. **Claim 10** The fiber placement head according to claim 6, further comprising a restart pinch roller that releasably engages with the restart power roller to hold the composite material tape segment.

Images