Patent Publication Number: US-2012036977-A1

Title: Cutter and anvil arrangement for a fiber placement head

Description:
FIELD OF THE DEVICE 
     The device relates to a head for applying fiber composite material to an application surface in which the individual lanes of fiber composite material are each driven by a drive roll and a backup roll that includes a cutter and an anvil for cutting the composite material. 
     BACKGROUND 
     Composite lay-up machines are well known in the art. Such machines can be divided into two basic types, fiber placement machines that lay bundles of individual fibers onto a surface, and tape laying machines that apply fiber composite material in the form of a wide tape onto a surface. If the surface that receives the fiber composite material is fairly continuous, and does not have a lot of contour, a tape laying machine is normally used. If the surface is highly contoured or discontinuous because of the presence of openings in the surface, a fiber placement machine is normally used. 
     SUMMARY 
     A fiber placement head for a fiber placement utilizes individual roller sets comprising a drive roll and backup roll for each tow lane in which each drive roll has a tow cutting and restarting mechanism carried on the roll&#39;s circumference. Each drive roll is geared to and meshes with a back-up roll that is half the diameter of the drive roll and that captures the tow material in a drive roll nip that is formed therebetween. The drive roll carries two cutters and two restarting zones, each of which are 180 degrees apart and that mesh with one anvil on the back-up roll. Each cutter has a blade edge that that is angled to provide a shearing motion across the anvil edge. Each cutter is mounted in the drive roll by a blade guide insert that can be ground to precisely control the position of the cutter on the drive roll. The anvil can be flipped over when one side wears out to renew the anvil cutting edge. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is perspective view of the fiber delivery mechanism in a fiber placement head. 
         FIG. 2  is a detail of a drive roll and a portion of a backup roll showing the two opposed cutting blades. 
         FIG. 3  is a detail sectional view showing the drive roll in position prior to cutting the composite material. 
         FIG. 4  is a detail sectional view showing the drive roll as the cutter begins to cut the composite material. 
         FIG. 5  is a detail sectional view showing the drive roll after the cutter has cut through the composite material. 
         FIG. 6  is a detail sectional view of the circular area shown in  FIG. 4  showing the cutter blade and the anvil. 
         FIG. 7  is a detail perspective view showing the cutter blade and the anvil. 
         FIG. 8  is a detail view taken along line  8 - 8  of  FIG. 6  showing the cutter blade prior to cutting the fiber tow. 
         FIG. 9  is a perspective view of an anvil. 
         FIGS. 10 and 11  are front and side views, respectively, of a cutter blade. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  is a perspective view of the fiber delivery mechanism  10  in a fiber placement head. The mechanism  10  comprises a frame structure  12  which supports an upper array of drive roll assemblies  14  and lower array of drive roll assemblies  16 . Each drive roll assembly comprises a drive roll  18  and a back-up roll  20  that is half the diameter of the drive roll  18 . Each drive roll assembly  14  and  16  feeds fiber composite material along a fiber composite path or lane to the compaction roll  22  located at the front of the frame as well known in the art. The fiber composite materials in the upper and lower lanes are interleaved at the compaction roll  22  to form a continuous layer of side-by-side strips on the application surface. The compaction roll  22  is formed by a series of side by side roller segments  24  so that the outer surface of the compaction roll may adapt to the contour of the surface to which the composite material is being applied. The frame  12  also supports an upper array of restart pinch roll assemblies  26  and a lower array of restart pinch roll assemblies  28  that are positioned between the drive roll assemblies  14  and  16 , respectively, and the compaction roll  22 . The restart pinch roll assemblies  26  and  28  drive the fiber composite material to the compaction roll  22  after the material has been cut by one of the cutters on the drive roll. 
       FIG. 2  is a detail view of a drive roll  18  and a portion of a backup roll  20 . The drive roll  18  is mounted by bearings (not shown) on a non-rotating drive roll hub  32  that is secured to the outside frame member  12 . The drive roll  18  may be driven by a drive pinion  34  that engages the internal gear teeth  35  of a ring gear  36  that is attached to the drive roll  18 . Rotation of the drive roll  18  is transferred to the backup roll  20  by a drive transfer arrangement that drivingly couples the drive roll and the backup roll together. In the embodiment shown, external gear teeth  38  on the ring gear  36 , best seen in  FIG. 3 , engage gear teeth  40  on the outside of the backup roll  20 , to positively couple the rotation of the drive roll to the backup roll. The drive roll has two cutter assemblies  48  spaced one hundred and eighty degrees apart so that a diameter line  39  joining corresponding parts of the two cuter assemblies passes through the center of rotation  41  of the drive roll. A drive surface  43  is formed on the outer circumference of the drive roll following each cutter assembly  48 . A tow ejector foot  66  is positioned between the cutter assembly  48  and the drive surface  43  of the drive roll. The backup roll has an anvil  80  mounted on its outer surface, and a backup drive surface  49  is formed on the outer surface of the backup roll following the anvil. A drive roll nip  42  is formed between the drive roll  18  and the backup roll  20 . Fiber tow  44  is delivered to the drive roll nip  42  from an upstream fiber path chute  46 , and passes through the drive roll nip  42  into a downstream fiber path chute  47 . 
       FIG. 3  is a detail sectional view showing the drive roll in position prior to cutting the composite material. The cutter assembly  48  comprises a cutter retainer  50 , a cutter blade  52 , and a cutter guide insert  56  having a blade guide surface  57 . The cutter retainer  50  is attached to the drive roll  18  by suitable fasteners such as screws  51  for rapid mounting and removal. The cutter blade  52  has a knife edge  54  and is mounted between the cutter retainer  50  and the blade guide surface  57  of the cutter guide insert  56 . The cutter guide insert  56  mounts into the drive roll and is secured by a fastener post  55 . The cutter guide insert  56  can be removed and the blade guide surface  57  can be ground to fit during assembly of the drive roll in order to precisely position the cutter blade  52  on the drive roll. The blade guide surface  57  is coincident with the diameter line  39  of the drive roll  18 . A similar cutter assembly  48  is mounted on the opposite side of the drive roll  18 , and the ability to precisely position the two diametrically opposed cutter blades  52  on the drive roll by means of the removable blade guide inserts  56  allows the cutter blades  52  to be precisely positioned on the diameter line  39 . This precise positioning of the two cutter blades  52  allows the blades to mate with the one anvil  80  on the back up roll  20 . 
     The cutter blade  52  has a ramp portion  58  and a spring retaining finger  60  that is formed below the ramp portion  58 . A compression spring  62  is located in a spring pocket  64  formed in the cutter blade retainer  50 , and the end of the spring  62  presses against the underside of the retaining finger  60 . A tow ejector foot  66  is positioned behind the cutter blade retainer  50  and is mounted on a pivot shaft  67 . The tow ejector foot  66  has a ramp surface  68  leading to a lobe  69 , and a return spring seat surface  70 . A compression spring  72  is mounted between the return spring seat surface  70  and another spring retaining surface (not shown) that is part of the drive roll assembly. A cam wheel  74  is mounted on a pivot  76  that is mounted on the non-rotating drive roll hub  32 . The cam wheel  74  is in a position to impact on the ramp surface  58  of the cutter blade  52  and the ramp surface  68  of the tow ejector foot  66  as these elements rotate past the cam wheel. An anvil  80  and an anvil retainer  82  are mounted on the outer circumference of the backup roll  20 . The anvil retainer  82  is held in place by one or more fastening elements such as a screw  81 .  FIG. 3  shows the drive roll in a position just before the cam wheel  74  impacts on the ramp surface  58  of the cutter blade  52 . 
       FIG. 4  is a detail sectional view showing the drive roll as the cutter begins to cut the composite material. Rotation of the drive roll  18  causes the cam wheel  74  to displace the cutter blade  52  against the force of the compression spring  62 , extending the knife edge  54  into the composite material  44  in the drive roll nip  42 . The blade  52  is actuated by the cam wheel along a line  53  that is coincident with the diameter line  39  that passes through the center  41  of the drive roll  18 . 
       FIG. 5  is a detail sectional view showing the drive roll after the cutter has cut through the tow material  44 . The knife edge  54  of the cutter blade  52  cuts through the composite material  44  and shears against the edge of the anvil  80  that is mounted on the back-up roll  20 . The synchronized rotation of the drive roll  18  and the backup roll  20  ensures that the anvil  80  is always in a shearing relationship with the cutter blade  52  when the cam wheel  74  impacts the cutter. In the position shown, the blade guide surface  57  is in alignment with the diameter line  39  of the drive roll  18  and the diameter line  78  that extends from the center  79  of the backup roll  20 . 
       FIG. 6  is a detail sectional view of the circular area shown in  FIG. 4  showing the cutter blade  52  and the anvil  80 . The anvil  80  is held in an anvil pocket  45  on the backup roll  20  by the anvil retainer  82 , and a recess  85  is formed between the body of the anvil  80  and the anvil retainer  82 . The knife edge  54  of the cutter blade extends into the recess  85  as it shears the fiber tow against the shear edge  83  of the anvil  80 . A guide foot  87  on one end of the shear edge  83  of the anvil is provided to receive and guide the tip  84  of the cutter blade  54  as the blade is driven into contact with the shear edge of the anvil. A tow pocket  86  is formed in the cutter blade  52  to allow the cutter blade to complete its cutting stroke without damaging the trailing end of the cut tow  44 . 
       FIG. 7  is a detail perspective view showing the cutter blade  52  and the anvil  80  after the drive roll  18  and the backup roll  20  have rotated past the position in which the cutter blade  52  cuts the tow material. The anvil  80  is held by the anvil retainer  82  in the anvil pocket  45  formed in the backup roll  20 . 
       FIG. 8  is a detail view taken along line  8 - 8  of  FIG. 6  showing the cutter blade prior to cutting the fiber tow. The cutting edge  54  of the blade is at an angle A to the shear edge  83  of the anvil  80 . The blade initially contacts the guide foot  87  on the anvil. The guide foot  87  positions the blade  52  so that it sweeps tightly across the shear edge  83 . The end  91  of the blade edge  54  that first contacts the guide foot  87  may be flattened to reduce the wear of the blade on the guide foot  87 . 
       FIG. 9  is a perspective view of an anvil  80 . Although the element  80  is called an anvil, it does not function as an anvil in the sense that the knife edge  54  of the cutter blade does not cut the fiber tow  44  by pressing the fiber tow against the anvil surface. A shear edge  83  is formed along the leading upper surface of the anvil  80 , and the cutter blade  52  cuts the tow by sweeping along the shear edge  83 . The anvil  80  has a mirrored design with two guide feet  87  and two shear edges  83 . This enables the anvil to be flipped over when one of the shear edges  83  wears so that the other shear edge can be used before replacing the anvil completely. 
       FIGS. 10 and 11  are front and side views, respectively, of a cutter blade  52 . The cutting edge  54  of the blade is at an angle A to a line  89  that is parallel to the shear edge  83  of the anvil  80 . The angle A may be between 5 and 25 degrees, and an angle of between 9 and 15 degrees is preferred. It has been determined that having an angle A on the blade provides an improved shearing motion across the shear edge  83 . The blade  52  features a ramp  58  that contacts the cam wheel  74 . The ramp  58  provides smooth and uniform motion of the blade  52  along the line of motion  53  as it rotates past the cam wheel  74  with minimum impact load on the cam wheel  74 . 
     Having thus described the invention, various modifications and alterations will be apparent to those skilled in the art, which modifications and alterations will be within the scope of the invention as defined by the appended claims.