Fiber placement machine for removing composite tape film

Abstract

A fiber placement head for applying multiple composite tape segments to a mold, comprising: a supply roller for storing and supplying a composite tape having a backing film to the fiber placement head; a film roller for receiving the backing film from the composite tape removed from the film roller; an electric motor that rotates the supply roller or the film roller; and a slip clutch coupled to the supply roller or the film roller, allowing relative displacement of the angular position of the film roller with respect to the angular position of the supply roller.

Description

Technical Field

[0001] This application relates to a fiber placement machine, and more particularly, to a fiber placement head that effectively manages the removal of a film from a composite tape. Background Art

[0002] Fiber placement machines are used to manufacture composite workpieces. A composite material in the form of a fiber material impregnated with resin is applied by the machine to a mold or mandrel at precise positions and lengths to jointly form a composite workpiece. The fiber placement machine moves a fiber placement head above the mold to precisely apply a composite tape in the final shape of the composite workpiece. As the fiber placement head moves, it leaves multiple composite tape segments, also known as courses, or tows, behind the mold. Although multiple composite tape bundles can be applied simultaneously as part of a course, the fiber placement head can control each tow individually as part of applying a course. The automatic application of these composite tape segments into the mold involves the cooperation of various machinery that can hold, move, and ultimately cut the composite tape.

[0003] The composite fiber tapes used in fiber placement machines can be impregnated with a resin that is activated by heating after or during application to the mold. The composite fiber tapes can be packaged on rolls or tubes such that the tape is wound around the roll or tube until it is needed. Then, the end of the tape is supplied into the fiber placement machine, which pulls the composite fiber tape out of the roll / tube. However, the resin pre-impregnated into the composite fiber tape can be somewhat sticky, so a film - sometimes referred to as a plastic interleave - can be provided on one side of the tape so that when the tape is stored on the tube / reel, one part of the composite fiber tape does not contact another part of the tape. This arrangement can prevent multiple parts of the composite fiber tape from inadvertently attaching to each other. The film is removed from the tape before application to the form or mandrel. It is advantageous to manage the film when it is removed from the composite fiber tape applied to the mold / mandrel. Summary of the Invention

[0004] In one embodiment, a fiber placement head for applying multiple composite tape segments to a mold includes a supply roll for storing and supplying a composite tape having a backing film to the fiber placement head; a film roll for receiving the backing film from the composite tape removed from the film roll; an electric motor for rotating the supply roll or the film roll; and a slip clutch coupled to the supply roll or the film roll, the slip clutch allowing a relative displacement of the angular position of the film roll relative to the angular position of the supply roll. Description of the Drawings

[0005] Figure 1 A perspective view of an embodiment of a fiber placement machine is depicted;

[0006] Figure 2Depicts another perspective view of an embodiment of the fiber placement head;

[0007] Figure 3 Depicts a perspective view of an embodiment of a portion of the fiber placement head;

[0008] Figure 4 Depicts a cross-sectional view of an embodiment of a portion of the fiber placement head;

[0009] Figure 5 Depicts another perspective view of an embodiment of a portion of the fiber placement head

[0010] Figure 6 Depicts another perspective view of an embodiment of a portion of the fiber placement head;

[0011] Figure 7 Depicts a cross-sectional view of an embodiment of a portion of the fiber placement head; and

[0012] Figure 8 Depicts a cross-sectional view of an embodiment of a portion of the fiber placement head. Detailed Description

[0013] A fiber placement machine may include a fiber placement head that carries one or more reels of composite tape for application to a mold. A number of composite tape segments may be applied to the mold and together form a composite part. When supplying the composite tape from the reel, a backing film (plastic scrim) may be removed from the tape. A supply spindle may carry the supply reel, and a separate film reel carried by a film spindle may receive the removed backing film from the composite tape as the tape is pulled from the supply reel. The film spindle may be connected to an electric motor that rotates the film spindle and helps maintain tension on the backing film collected by the film spindle. Initially, when the supply reel of the composite tape includes an initial amount of tape, it is at an initial diameter. As the composite tape is removed from the supply reel and the backing film is received by the film spindle, the diameter of the supply reel decreases and the diameter of the film reel increases. The changing diameters of the supply reel and the spindle reel may change the diameter ratio of these reels. A slip clutch may be coupled to either the supply spindle or the film spindle such that the electric motor rotating the film spindle can rotate at an angular velocity greater than that of the supply spindle and the film spindle, thereby maintaining tension on the composite tape and the backing film when removing the backing film from the tape.

[0014] Figure 1An embodiment of a fiber placement machine 10 is shown. The fiber placement machine 10 includes a robotic arm 12 that is removably coupled to a fiber placement head 14. The robotic arm may be supported by a base 16 on which the robotic arm moves linearly about an axis (x). A plurality of movable segments 18 that can be moved, for example, by pivoting, rotating, or telescoping, may extend outwardly from the base 16. The robotic arm 12 may be movable relative to the base 16 about a plurality of axes. For example, a first segment 18a may be rotatably coupled to the base 16 at one end such that the robotic arm 12 can 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 move telescopically away from and toward the third segment. The segments 18 may be moved relative to each other using fluid pistons, electric motors, or some combination of these or other drive elements to move the distal end of the robotic arm 12 relative to a mold 20 or mandrel for manufacturing a workpiece.

[0015] A microprocessor (not shown) in communication with a computer-readable storage medium having executable instructions may control the movement of the fluid pistons, electric motors, or other drive elements, and thus control the movement and position of the movable segments 18 of the robotic arm 12. The microprocessor may be any type of device capable of processing electronic instructions, including microcontrollers, main processors, controllers, and application-specific integrated circuits (ASICs). It may be a dedicated processor solely for performing the control of the robotic arm 12 or may be shared with other machine functions. The microprocessor executes various types of digital storage instructions, such as software or firmware programs stored in a memory. Communication between the mechanism for moving the robotic arm, such as a fluid piston or an electric motor, and the microprocessor may be performed via a communication bus.

[0016] The robotic arm 12 can move the fiber placement head 14 along three axes to position the head 14 for servicing or applying a composite tape to the mold 20. While this is one embodiment of the robotic arm 12 that can be used with a fiber placement head, other embodiments of robotic arms or mechanical devices for applying composite tapes may also be used. The end of the robotic arm 12 remote from the base 16 may include a chuck 22 that releasably engages the fiber placement head 14. The chuck 22 and a portion of the fiber placement head 14 may 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 orthogonally to the surface of the head 14. The robotic arm 12 can position the chuck 22 to engage the shank and the fiber placement head 14 is elastically coupled to the arm 12.

[0017] As Figures 2 - 6As shown, the fiber placement head 14 can include a creel frame 24, a plurality of spools 26 that carry composite tape as a tape source for the head 14, and a cut, clamp, restart (CCR) assembly 32. The CCR assembly 32 can include a compaction roller 34 (or alternatively a compaction slider) that can receive the composite tape from the spools 26 and apply it to the mold 20 to fabricate a composite part. The creel frame 24 includes a plurality of outer surfaces 36 and spindles 38 mounted orthogonally with respect to the outer surfaces 36. In some embodiments, a pneumatic, mechanical, or fluid-controlled dancer element can be used to move the spindles 38 to create tape tension, which helps maintain tension on the composite tape when applying the tape to the mold 20. More specifically, as Figures 3 - 6 shown, the fiber placement head 14 can include a supply spool 26a and a film spool 26b carried by a supply spindle 38a and a film spindle 38b, respectively. A dancer roller 28 can also be carried by the fiber placement head 14 to help manage the tension of the composite tape as it unwinds from the supply spool 26a. In one embodiment, the dancer roller 28 can move along a linear slider 29 in response to a force provided by a dancer arm 30. This will be discussed in more detail below. The composite tape can unwind from the supply spool 26a, travel past the dancer roller 28 to the film spool 26b where a backing film is gathered, and enter the compaction roller 34 for eventual application to the mold 20.

[0018] A portion of the inner surface 42 of the fiber placement head 14 is at Figures 3 - 4Shown in. The various components included in the fiber placement head 14 are shown near the inner surface 42. For example, the fiber placement head 14 can include a rotary drive 46 that mechanically couples the film spindle 38b to the supply spindle 38a and a supply reel tensioner 50. The supply reel tensioner 50 can include an electric motor to rotate the supply spindle 38a. In this embodiment, the rotary drive 46 can include an endless loop 47, such as a belt or a chain, that engages both a film pulley 54 attached to the output shaft 45 of the film reel 26b and a supply pulley 52 that is ultimately coupled to the supply spindle 38a through a slip clutch 48. In some embodiments, the slip clutch 48 can be located near the axial end of the supply reel 26a, while in other embodiments, the clutch 48 can be located radially inside the composite material carried by the supply reel 26a. The diameters of the supply pulley 52 and the film pulley 54 can be selected to maintain a specific ratio. This will be discussed in more detail below. The film pulley 54 and the supply pulley 52 can include a grooved outer axial surface for accommodating an endless loop of a corresponding shape, such that an increased tension correspondingly increases the friction between the endless loop 47 and the pulleys 52, 54. Alternatively, in another embodiment, the pulleys 52, 54 can include radially outward teeth that engage an endless loop implemented as a chain. A dancer idler 58 that includes an idler pulley that is biased into contact with the endless loop can be used to maintain the tension on the endless loop. However, other embodiments are also possible, where the rotary drive is implemented as a gear connection between the output shaft 45 and the supply spindle 38a. In this embodiment, the supply reel tensioner 50 can maintain a defined level of torsional resistance on the supply spindle 38a. The supply reel tensioner 50 can include a servo motor having an output coupled to the endless loop 47 that engages a tension pulley 56 attached to one end of the supply spindle 38a. However, other embodiments are also possible, where the servo motor is axially aligned with the supply spindle 26a and includes an inline gear reducer that is coaxial with the spindle rotation axis.

[0019] The slip clutch 48 may include a clutch input 60 coupled to the supply pulley 52 and a clutch output 62 engaged with and rotating the supply shaft 38a. Below and up to or below a certain amount or level of torque applied to the clutch input 60, the clutch input 60 maintains a fixed angular position relative to the clutch output 62. Once the torque level is exceeded, the slip clutch 48 allows the clutch input 60 to change its angular position relative to the clutch output, thereby limiting the amount of torque transmitted from the clutch input 60 to the clutch output 62. The slip clutch may be implemented in any of a variety of ways, and the amount of torque at which angular displacement occurs may be selected. For example, one or more friction pads may be positioned between the clutch input 60 and the clutch output 62 along the axis of rotation. The clutch input 60 and the clutch output 62 may be coupled to opposite ends of the friction pads. In some embodiments, an axial screw used with a collar may be used to increase or decrease the pressure between the friction pads, thereby increasing or decreasing the torque value at which the clutch output 62 angularly displaces relative to the clutch input 60. The diameter ratio of the supply pulley 52 to the film pulley 54 may be selected such that when the electric motor is operating, the clutch input 60 angularly displaces relative to the clutch output 62, regardless of whether the supply reel 26a is in an initial state (initial diameter), fully wound with the composite tape, or whether the supply reel 26a is in an exhausted state, where a large amount of backing film is wound around the film spindle 38b.

[0020] Go to Figure 7 , a cross-sectional view of an embodiment of the supply reel 26a in an initial state is shown, and in Figure 8 a cross-sectional view of an embodiment of the supply reel 26a in an exhausted state is shown. In Figure 7In it, the supply reel 26a is wound with the composite tape 64 to full capacity. In this embodiment, the supply reel 26a at full capacity can have a diameter of 8 inches and the film reel 26b can have a diameter of 2.5 inches when empty or nearly empty. Given the angular velocity of the output shaft 45, the ratio between the supply reel 26a at full capacity and the empty film reel 26b is 3.2:1. When the composite tape 64 is supplied to the fiber placement head 14 and deposited on the mold 20, as the film reel 26b receives the backing film 66 removed from the composite tape 64, the diameter of the supply reel 26a decreases while the diameter of the film reel 26b increases. When the composite tape 64 has been removed from the supply reel 26b and the backing film 66 from the removed tape 64 is wound on the film reel 26b, the diameter of the supply reel 26a is 3 inches while the diameter of the film reel 26b is 6.5 inches; the ratio between the depleted supply reel and the film reel filled with the backing film 66 is 1:2.2. The electric motor can rotate the supply pulley 52 relative to the film pulley 54 at an angular velocity such that in one embodiment, there is a ratio of 4:1 so that regardless of the change in the diameters of the supply reel 26a and the film reel 26b, the supply main shaft 38a can be overdriven such that the clutch input 60 undergoes an angular displacement relative to the clutch output 62, thereby maintaining the tension of the backing film 66 when removed from the composite tape 64. At an output shaft angular speed of 2400 revolutions per minute (RPM), the supply reel 26a can rotate at an angular rotation rate of 95.5 RPM while the film reel 26b can rotate at an angular rotation rate of 306 RPM. After all or almost all of the composite tape 64 has been pulled out from the supply reel 26a, the supply reel 26a can rotate at an angular rotation rate of 241 RPM and the film reel can rotate at an angular rotation rate of 118 RPM.

[0021] 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 is defined only by the following claims. Further, the statements included in the foregoing specification relate to particular embodiments and should not be construed as limiting the scope of the present invention or the definition of terms used in the claims, unless the terms or words are explicitly defined above. Various other embodiments and various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. All such other embodiments, changes, and modifications shall fall within the scope of the appended claims.

[0022] As used in this specification and the claims, the terms "such as", "for example", "e.g.", "such", and "like" and the verbs "comprising", "having", "including", and their other verb forms, when used in conjunction with a list of one or more components or other items, each shall be interpreted as open-ended, meaning that the list should not be regarded as precluding other, additional components or items. Other terms shall be construed in their broadest reasonable sense unless used in a context requiring a different interpretation.

Claims

1. A fiber placement head for applying multiple composite tape segments to a tool, comprising: A supply roller for storing and supplying a composite tape having a backing film to the fiber placement head; A film roller for receiving the backing film from the composite tape removed from the film roller; An electric motor that rotates the supply roller or the film roller; And A slip clutch coupled to the supply roller or the film roller, the slip clutch including a clutch input and a clutch output that engages a supply spindle, wherein the clutch output is configured to undergo an angular displacement relative to the clutch input to allow a relative displacement of the angular position of the film roller relative to the angular position of the supply roller.

2. The fiber placement head according to claim 1, further comprising a floating roller that receives the composite tape from the supply roller and conveys the composite tape on an outer surface of the film roller while maintaining tension on the composite tape.

3. The fiber placement head according to claim 1, wherein, The supply pulley rotates at an angular velocity relative to the film pulley such that there is a ratio of 4:1, so that the supply spindle can be overdriven regardless of changes in the diameters of the supply spool and the film spool.

4. The fiber placement head according to claim 3, wherein, The rotary drive includes the supply pulley, the film pulley, and an annular ring.

5. The fiber placement head according to claim 1, further comprising a film spindle for carrying the film roller and receiving a rotational input from the electric motor.

6. The fiber placement head according to claim 1, wherein, The supply spindle is for carrying the supply roller and receiving a rotational input from the electric motor.

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