OVERLAY SHEET TENSIONER APPARATUS

Abstract

An apparatus is provided for handling overlay sheet material on a cutting apparatus including a conveyor for moving work material in a longitudinal direction and a support for positioning a tensioner frame adjacent the conveyor. A tensioner frame, attached to the support, has a nip wheel and a drive for rotating the nip wheel with a tangential speed in excess of the longitudinal conveyor speed attached to the tensioner frame. The nip wheel engages the overlay sheet material applying a tension thereto in the same longitudinal direction as the conveyor.

Claims

1. An apparatus for handling overlay sheet material on a cutting apparatus, comprising: a conveyor for moving work material in a longitudinal direction in the cutting apparatus; a support for positioning a tensioner frame adjacent the conveyor; a tensioner frame attached to the support; a nip wheel rotatably attached to the tensioner frame; and a drive attached to the tensioner frame for rotating the nip wheel with a tangential speed in excess of the longitudinal conveyor speed; wherein the nip wheel engages the overlay sheet material applying a tension thereto in the same longitudinal direction as the conveyor.

2. An apparatus for handling overlay sheet material on a cutting apparatus in accordance with claim 1, wherein the drive further comprises an electric motor operatively connected to the nip wheel.

3. An apparatus for handling overlay sheet material on a cutting apparatus in accordance with claim 1, wherein the drive further comprises a drive wheel operatively connected to the nip wheel.

4. An apparatus for handling overlay sheet material on a cutting apparatus in accordance with claim 1, further comprising a slip clutch on the nip wheel.

5. An apparatus for handling overlay sheet material on a cutting apparatus in accordance with claim 1, wherein the support provides for the tensioner apparatus to move between a first active position and a second inactive position.

6. An apparatus for handling overlay sheet material on a cutting apparatus in accordance with claim 1, wherein the tangential speed of the nip wheel is approximately 20% faster than the longitudinal conveyor speed.

7. A method for handling overlay sheet material on a cutting apparatus, comprising: moving overlay sheet material in a longitudinal direction on a conveyor of the cutting apparatus; engaging the overlay sheet material with a nip wheel rotatably attached to a support adjacent the conveyor; rotating the nip wheel with a drive having a tangential speed in excess of the longitudinal conveyor speed; and attaching a nip wheel rotatably to the tensioner frame; and applying tension to the overlay sheet material in the same longitudinal direction as the conveyor.

8. A method for handling overlay sheet material on a cutting apparatus in accordance with claim 7, wherein rotating the nip wheel with the drive further comprises using an electric motor operatively connected to the nip wheel.

9. A method for handling overlay sheet material on a cutting apparatus in accordance with claim 7, wherein rotating the nip wheel with the drive further comprises using a drive wheel operatively connected to the nip wheel.

10. A method for handling overlay sheet material on a cutting apparatus in accordance with claim 7, wherein rotating the nip wheel with the drive further comprises using a slip clutch on the nip wheel.

11. A method for handling overlay sheet material on a cutting apparatus in accordance with claim 7, wherein engaging the overlay sheet material with a nip wheel rotatably attached to a support further comprises moving a tensioner apparatus between a first active position and a second inactive position.

12. A method for handling overlay sheet material on a cutting apparatus in accordance with claim 7, comprising rotating the nip wheel at a tangential speed 20% faster than the longitudinal conveyor speed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a perspective view of an overlay sheet tensioner in accordance with a first embodiment of the invention in an active position;

[0011] FIG. 2 is a perspective view of the overlay sheet tensioner of FIG. 1 in operation;

[0012] FIG. 3 is a perspective view of the overlay sheet tensioner of FIG. 1 in an inactive position;

[0013] FIG. 4 is a perspective view of an overlay sheet tensioner in accordance with a second embodiment of the invention in an active position;

[0014] FIG. 5 is a perspective view of the overlay sheet tensioner of FIG. 4 mounted on a take-off table;

[0015] FIG. 6 is a perspective view of the overlay sheet tensioner of FIG. 4 in an inactive position; and

[0016] FIG. 7 is a perspective view showing a cutting machine in which the present invention may be embodied.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Referring to FIG. 7, an apparatus 10 is shown for cutting a single ply or multiple plies 12 of limp material 13, referred to as a layup 14, into individual parts 16 of predetermined size and shape includes a cutting apparatus 20 and a take-off table 23. The cutting apparatus 20 includes a cutter table 24 for supporting the layup 14 and a cutter head 26 movable with respect to the cutter table 24.

[0018] The cutter table 24 includes a frame 32 and extends in a lateral, or Y-coordinate, direction from a console side 34 to a remote side 36 and in a longitudinal, or X-coordinate, direction from a take-on end 40 to a take-off end 42. The cutter table includes a conveyor 44 with a permeable bristle surface 46 that advances the layup 14 in the X-coordinate direction.

[0019] A cutter beam 52 supports the cutter head 26 and is movable in the X-coordinate direction along a pair of guide rails 54 secured to the cutter frame 32. The cutter beam also supports the camera 30 mounted on the other side of the beam 52 to avoid interference with the cutter head 26. The cutter head 26, which cuts the layup 14, and the camera 30, which scans the upper ply 12, move in the lateral or Y-coordinate direction across the cutter beam 52. A cutter tool 56 is supported within the cutter head 26.

[0020] The cutting apparatus 20 also includes an operator control panel 62 formed substantially integrally with the beam 52 and including a plurality of function buttons. The cutting apparatus 20 also includes a computer 66 with a monitor 68 and a keyboard 70 for controlling various cutting operations. The computer 66 includes data 72 such as cut data and matching data.

[0021] A roll of thin air-impermeable overlay material 96 is disposed substantially adjacent to the take-on end 40 of the cutter table 24 of the cutter apparatus 20. A layer of the thin overlay material 96 is spread over the air-permeable layup 14 for facilitating vacuum hold-down of the layup 14 during cutting operations.

[0022] A take-off table 23 is disposed at the take-off end 42 of the cutter table 24 for accommodating cut parts 16 subsequent to the cutting operation. The take-off table 23 includes a conveyor 50 that clears the material advanced from the cutter table 24.

[0023] In accordance with the invention, an overlay material tensioner is provided adjacent the take-off end 42 of cutter table 24 for maintaining tension on the overlay material as it comes off of cutter table 24 onto take-off table 23. The overlay tensioner may be rotatably mounted on a pivot support rod 108 fixedly attached to the side of cutter table 24 and/or take-off table 23. Preferably, two overlay material tensioners are provided per cutting table, one on each side of take-off table 23.

[0024] As shown in FIG. 1, a first embodiment of an overlay material tensioner 102 in accordance with the invention includes a tensioner frame 104 adapted at one end 106 to rotate about a pivot support rod 108 via hole 110, an electric motor 112 mounted on the tensioner frame 104 and a nip wheel 114 at the other end 116 of the tensioner frame 104 for engaging with the overlay material 96. The rotor shaft of the electric motor 112 is connected to a belt drive pulley 118 to transfer power via a drive belt 119 to a belt drive pulley 120 connected to the axle of the nip wheel 114. The belt drive pulley 120 of the nip wheel 114 may include a slip clutch 122 to control the amount of power transferred from the electric motor 112 to the nip wheel 114. It will be appreciated that the surface of the nip wheel 114 should have high coefficient of friction to insure firm engagement with the overlay material 96.

[0025] In a first active position, shown in FIG. 2, the overlay material tensioner 102 may engage the overlay material 96 between the nip wheel 114 and the take-off table 23 adjacent the take-off end 42 of cutter table 24. An enable switch (not shown) may be provided such that when the overlay material tensioner 102 is in the active down position the electric motor 112 may be energized by a conveyor signal of the cutting table 24.

[0026] It may be appreciated that by setting an appropriate electric motor speed, a tension is created in the overlay material 96 preventing gathering and bunching of the overlay material. The overlay material tensioner 102 applies tension to the overlay material 96 by trying to drive nip wheel 114 significantly faster than the take-off table conveyor 50. The slip clutch 122 allows the surface speed of the nip wheel 114 to match the surface speed of the take-off table conveyor 50, while generating an adjustable pull force (tension) on the overlay material 96. This tensioning action depends on there being a difference in the coefficients of friction between the nip wheel 114 to overlay material 96 and the overlay material 96 to take-off table conveyor 50.

[0027] The slip clutch torque should be set so that it creates as much tension on the overlay material 96 as possible without tearing the overlay material 96 or creating “excessive” stretching. Slip clutch torque may be adjusted manually by turning the adjustment knob 124 on the slip clutch 122. It will be appreciated that the amount of downward pressure/contact force exerted by nip wheel 114 is important. The higher the downward pressure/contact force, the greater the drive torque necessary and the greater the chance of damaging the overlay material 96 as the overlay material moves relative to the surface of the take-off table conveyor 50, and the less likely the overlay material 96 will actually be able to move across the surface of the take-off table conveyor 50 due to mechanical interlocking of the surfaces. It may be generally advantageous to maintain a relatively low contact force. However, if the contact force is too low, then the lateral tension force will be limited, since the tension force is a product of the contact force and the coefficient of friction between nip wheel 114 and the overlay material 96. Thus, these forces must be balanced in a manner known to those skilled in the art.

[0028] Preferably, the tangential speed of the nip wheel 114 should be approximately 20% faster than the surface speed of the take-off table conveyor 50. It may be appreciated that a benefit of a relatively large speed differential is minimization of the bunching/pleating of the overlay material. A higher speed differential, however, may negatively impact slip clutch life.

[0029] In a second inactive position, shown in FIG. 3, the overlay tensioner 102 in accordance with the invention may be rotated about the pivot support rod 108 so that the overlay tensioner 102 is out of the way for operator operations on the cut material.

[0030] As shown in FIG. 4, a second embodiment 202 of an overlay material tensioner in accordance with the invention includes a first tensioner frame 204 and a second tensioner frame 206. The first tensioner frame 204 comprises an upper frame element 208 and a lower frame element 210. The upper frame element 208 is adapted at one end 210 to rotate about a pivot support rod 207 via hole 211 and the other end 212 is slidably connected to the lower frame element 210. The upper frame element 208 and the lower frame 210 element may be connected by a shock absorber 214.

[0031] The second tensioner frame 206 includes a knurled drive wheel 216 and nip wheel 218 rotatably mounted thereon. The axle of the knurled drive wheel 216 is connected to a belt drive pulley 219 to transfer power via a drive belt 221 to a belt drive pulley 220 connected to the nip wheel 218. The belt drive pulley 220 of the nip wheel 218 may include a slip clutch 222 to control the amount of power transferred from the knurled drive wheel 216 to the nip wheel 218. The knurled drive wheel 216 is sized relative to nip wheel 218 such that the tangential speed of the nip wheel is approximately 20% faster than that of the knurled drive wheel 216.

[0032] In a first active position, shown in FIG. 5, the knurled drive wheel 216 of the overlay material tensioner 202 engages moving take-off table conveyor 50 through the overlay material 96 thereby rotating the knurled drive wheel 216. The belt drive between the knurled drive wheel 216 and the nip wheel 218 rotates the nip wheel 218 adjacent the take-off end 42 of cutter table 24 thereby preventing gathering and bunching of the overlay material 96 as it exits from cutter table 24. The knurled drive wheel 216 requires enough contact force/downward pressure to engage the take-off table conveyor 50 without slipping; The contact force/downward pressure of nip wheel 218 are similar to the motor driven embodiment described above.

[0033] In a second inactive position, shown in FIG. 6, the overlay tensioner 202 may be rotated about the pivot support rod 207 so that the overlay tensioner is out of the way for operator operations on the cut material.

[0034] While the present invention has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art, that various modifications to this invention may be made without departing from the spirit and scope of the present invention.