APPARATUS FOR COMPOSITE TAPE DISPENSING
Technical Field
The present invention relates to an apparatus for dispensing composite tape,
and more particularly, to an apparatus for laying down prepreg tapes with precision.
The apparatus can lay down prepreg onto a molding structure having a contoured
surface or a flat surface along a linear or non-linear path.
Background
In composite technology, a resin preimpregnated web or tape may be used to
construct the particular component desired. Prepreg materials consist of aligned
reinforcing fibers (typically carbon, glass, or aramid fibers) that are pre-impregnated
with a polymer and used as an intermediate product in the molding of composite
structures. Very often these fibers are collimated in a unidirectional configuration
forming tape-like products that are typically 12 to 60 inches (30.5 to 152.4 cm) wide.
The composite structure is built up of successive layers of the tape applied to
a working surface such as, for example, a molding tool, mandrel, or any surface
used to form composite parts. When building up a composite wind blade, wind blade
spar, or wing structures, for example, from prepreg tapes, long lengths (i.e., greater
than 40 meters) of prepreg tape are laid down on a molding tool with great precision.
Precise filament alignment is required to achieve the desired composite properties.
In addition, uniform compaction of the prepreg tape during the laminate build-up is
required to minimize entrapped air, which can cause voids in the cured composite
laminate. Very slight misalignment of fiber orientation can cause significant loss of
critical engineering properties. For example, 5 to 10 degrees off orientation can
cause a 10 to 20% loss in composite modulus of elasticity. Voids in the composite
can also result in lower composite properties. Greater than 2% voids can cause
significant loss of inter-laminar shear strength and can act as sites for damage
growth in the composite during service life.
Composite wind blade spars are often straight-sided laminates of varying
thickness, for example, from approximately 0.1 inch (0.25 cm) to over 1.5 inches
(3.81 cm) thick. They are typically laid up mold surfaces that can range from flat to
varying degrees of concave or convex curvature. For example, the wind blade spar
may be flat at the tip and curved at the root. This configuration further adds to the
complexity of laying down prepreg tapes with extreme precision. Hand layup of
these spars with prepreg tapes is extremely difficult and time consuming, and
assuring precision is even more difficult. The alternate extreme to hand layup
involves the use of automated tape laying machines. These types of machines have
been developed for over two decades, primarily for aerospace structures. While
these machines are designed to lay down prepreg tapes with extreme precision,
these machines are very expensive and overly complex for wind blade spars.
Summary
The present invention is directed to an apparatus that is capable of laying
down a wide prepreg product for a structure having in-plane curvature, while
significantly reducing the effects of wrinkling on the inner radius.
In one aspect of the invention, there is provided an apparatus to apply a resin
impregnated tape to the surface of a molding tool, the apparatus including: an upper
frame rotatably mounted to a base frame, the upper frame having mounted thereon
and rotatable therewith a spool holding assembly for holding a spool of resin
impregnated tape wound thereon, a tape compaction assembly including a
compaction roller configured to conform to the surface of the molding tool for
compacting the resin impregnated tape onto the surface of the molding tool, and a
tape tensioning system for exerting tension on the resin impregnated tape. The base
frame includes a tracking system for tracking the surface of the molding tool, the
base frame being reciprocally movable with respect to the surface of the molding
tool.
In one embodiment, the spool holding assembly includes an alignment system
for laterally aligning the spool of prepreg tape relative to the surface of the molding
tool.
In one embodiment, the compaction roller includes a plurality of contiguous
disks supported on an axle, the disks having a central bore diameter that is greater
than the outer diameter of the axle.
In one embodiment, the upper frame rotates at least 180° on the base frame
to permit changing the direction of application of the resin impregnated tape on the
surface of the molding tool. The apparatus may further include a turntable coupled
to the upper frame and the base frame to permit rotation of the upper frame on the
base frame.
In one embodiment, the tape tensioning system includes an actuated disk
brake. The disk brake may be manually or automatically actuated.
In one embodiment, the molding tool includes at least one rail and the tracking
system includes at least two guide rollers that engage the at least one rail.
The surface of the molding tool may include at least one of a convex contour
and a concave contour.
The width of the resin impregnated tape applied to the molding tool, in one
embodiment, is within the range of about 11.5 inches (292 mm) to about 60 inches
( 152.4 cm).
In a further aspect of the invention, that apparatus further includes a slitter for
slitting the resin impregnated tape lengthwise into a plurality of strips, the slitter
mounted on and rotatable with the upper frame. The slitter may include a plurality of
stationary or rotary knives.
In one embodiment, the plurality of strips of resin impregnated tape is uniform.
In another embodiment, the width of the plurality of strips of resin impregnated tape
is non-uniform.
In one embodiment, the apparatus further includes a plurality of accumulator
rollers disposed downstream of the slitter, each accumulator roller being
independently activatable for accumulating and de-accumulating a portion of a
respective strip of resin impregnated tape, the accumulator rollers mounted on and
rotatable with the upper frame.
In one embodiment, the apparatus further comprising a controller configured
to control at least one of: the placement of the resin impregnated tape on the surface
of the molding tool; the tension exerted by the tensioning system on the tape; the
direction in which the tape is applied to the surface of the molding tool; and the
speed at which the tape is applied to the surface of the molding tool.
Brief Description of the Drawings
In the annexed drawings, like references indicate like parts or features:
FIG. 1 is a perspective view of an apparatus for laying down prepreg tape
according to an embodiment of the invention.
FIG. 2 is a top view of the apparatus of FIG. .
FIG. 3 is a front view of the apparatus of FIG. 1 with a spool of prepreg
material mounted thereon.
FIG. 4 is a side view of the apparatus of FIG. 1 with a spool of prepreg
material mounted thereon.
FIG. 5 is a perspective view of an embodiment of the apparatus for laying
down prepreg tape according to the invention as positioned on a molding tool.
FIG. 6 is a front view of the apparatus of FIG. 5 .
FIG. 7 is a perspective view of the apparatus of FIG. 5, illustrating rotational
motion of the upper frame.
FIG. 8 is a perspective view of an apparatus for laying down prepreg tape that
includes tape slitting and dispensing assemblies in accordance with an embodiment
of the present invention.
FIG. 9 is a side view of the apparatus of FIG. 8 .
FIG. 10 is a top view of the apparatus of FIG. 8 .
FIG. 11 is an enlarged top view of the tensioning system of the apparatus of
FIG. 8 .
FIG. 12 is a side view of a section of the apparatus of FIG. 8 with a spool of
prepreg material mounted thereon.
FIG. 3 is a perspective view of the tape alignment assembly of the apparatus
of FIG. 8 .
FIG. 14 is a bottom view of the tape positioning assembly of the apparatus of
FIG. 8 .
FIG. 15A is a schematic drawing illustrating a prepreg tape dispensed using
conventional apparatus in a linear direction.
FIG. 15B is a schematic drawing illustrating a prepreg tape dispensed using
conventional apparatus in a non-linear direction.
FIG. 16 is a photograph showing a prepreg tape dispensed using
conventional apparatus onto a curved surface.
Detailed Description
The apparatus of the present invention is useful for forming composite
laminated structures by applying tape of continuous fibers that have been
preimpregnated with a resin binder onto a surface of a mold, mandrel or tool. The
fibers may consist of carbon, glass, ceramic, metal, and/or polymers. The resin
binder may be a thermoset or thermoplastic resin.
In one aspect of the invention, an apparatus for laying down a wide,
unidirectional prepreg tape for a structure, and in particular, for a wind blade, is
provided. The apparatus includes a spool holder for demountably holding a spool of
a continuous web of prepreg material having a wide width. The apparatus includes a
mechanism for properly placing the prepreg on the surface of the molding tool. In
addition, the apparatus includes a rotatably mounted prepreg tape placement
assembly for bi-directional tape placement and compaction.
The width of the prepreg tape product is typically in the range of about 11.5
inches (292 mm) to about 60 inches (152.4 cm). In one embodiment, the width of
the prepreg tape is about 12 inches (30.5 cm) to about 60 inches ( 152.4 cm), or
about 11.5 inches (292 mm) to about 15.75 inches (400 mm). In general, it is
advantageous to use wider prepreg tape so as to increase the rate of prepreg tape
lay down, and thus increase production efficiency. With the apparatus of the present
invention, it is possible to further increase production rates by providing bi-directional
tape placement and compaction. Application of the prepreg material on the molding
tool may be carried out in the forward direction and in the reverse direction.
Referring to FIGS. 1-3, in one embodiment of the invention, the prepreg tape
laying apparatus is a carriage 10 that includes an upper frame 12 rotatably mounted
to a base frame 14. Mounted on the upper frame 12 are a prepreg spool holding
assembly 16 and a compaction assembly 18 . The base frame 14 includes a tracking
system 20 to precisely place the prepreg material on the surface of the molding tool.
The spool holding assembly 16 includes a spindle 22 and spool supports 24
mounted on spindle 22. Spool supports 24 include quick-adjust pins 26 that contact
the inside of the prepreg spool core to center the spool 80 on the spindle 22. The
spool holding assembly 16 enables rapid prepreg spool change-out and positioning.
Spindle 22 is supported at each end by trusses 28 on the upper frame 12 .
Referring to FIG. 3, the carriage 10 includes a spool positioning system 30
that includes disk 32 and lateral adjustment bracket 34. The spool positioning
system 30 controls the lateral position of the spool of prepreg material on the
carriage throughout the prepreg dispensing operation. Disk 32 is fixed to spindle 22.
The disk 32 is positioned between the arms of a U-shaped bracket 34. A pad 36
coupled to each arm of the bracket 36 contacts the disk 32. Using positioning
handle 3 1, small lateral (i.e., perpendicular to the direction of tape application)
adjustments in the alignment of the prepreg tape can be made by laterally moving
the bracket 34 during tape dispensing as necessary.
The carriage 10 includes a tensioning system 38 for maintaining a suitable
level of tension on the prepreg material during dispensing operation. A friction
adjuster 40 applies pressure to the disk 32 and pads 36 within the bracket 34 to
establish a baseline resistance to rotation of the prepreg roll during the dispensing
operation. This adjuster 40 can be either manually operated or automatically
operated based on feedback from tension monitoring sensors (not shown).
The tensioning system 38 includes a spring-loaded arm 42 that provides a
measurement of the tension on the prepreg tape. The force of the spring 44 on the
spring-loaded arm 42 also compensates for minor fluctuations in force that result
from the propulsion of the prepreg dispensing carriage 10 and from the diametric
change of the prepreg material as it is dispensed from the spool. In one
embodiment (not shown), the tensioning system may further include sensors for
tension monitoring and adjustment. Tension roller 47 attached to lateral bar 46
positions the prepreg tape near the surface of the molding tool in preparation for the
compaction step.
The compaction assembly 18 acts to press down the prepreg material as it is
dispensed onto the surface of the molding tool. The compaction assembly applies
compaction pressure regardless of the twist and curvature of the molding tool
surface. A compaction roller 48 is made up of a plurality of thin, heavy contiguous
disks 50 on a lateral axle 52 with the flat faces of the disks pressed together. The
disks 50 have a central bore diameter that is larger than the diameter of the axle 52.
The disks 50 have polished faces and/or friction reducing media on the faces of the
disks to enable independent movement of each disk. The heavy disks 50 are able to
move vertically, so that the edge of each disk contacts the prepreg material to
provide compaction. Adjacent the last disk at each end are retention members 54 on
the axle 52 to maintain the lateral position of the disks 50 and limit their motion to
rotation about the axle and translation perpendicular to the axle 52. Swing away arm
56 of the compaction assembly 18 is pivotably mounted on the upper frame 12 at
pivot point 58. The rotational movement of the compaction assembly 18 enables the
operator to lift the compaction assembly off of the prepreg tape when the compaction
assembly is not in use. The compaction assembly 18 may optionally include other
features, including flexible-urethane or pneumatic shaped rollers, and spring or
pneumatic loaded "fingers'Varms (not shown).
Referring to FIG. 4, as the prepreg material 82 is unwound from the spool 80,
it passes over redirect roller 43 and is then positioned near the surface of the
molding tool by tension roller 47. The carriage 10 travels across the surface of the
molding tool in the direction indicated by the arrow. The compaction assembly 18 is
lowered so that compaction roller 48 contacts the prepreg tape 82 and applies
compaction pressure to compress the prepreg tape 82 to the surface of the molding
tool 60.
Referring to FIGS. 5 and 6, the carriage 10 may be moved over the surface
64 of a molding tool 60 by wheels 70 positioned on each of the four corners of the
base frame 14. The carriage 10 may be self-propelled using, for example, an
electric motor (not shown). In one embodiment, the carriage 10 is guided by a rail 62
positioned along the surface of the molding tool 60.
In the illustrated embodiment, the components of the tracking system 20 of
the carriage 10 are integrated into the carriage 10 and are coordinated with the
configuration of the molding tool 60 to assure the proper placement of the prepreg
tape. Typically, the coordination focuses on a specific feature of the final composite
structure. As an example, the point where the centerline of a wind blade spar cap
contacts the surface of the molding tool 60 may be used as a "key characteristic".
Tracking system 20 maintains precise position of the prepreg dispensing carriage
relative to the key characteristic. Components of the tracking system 20 may be
embedded in the molding tool surface 64 or in a separate guide rail 62 positioned on
the edges of planar portions 68 of the molding tool at either side of a central concave
portion 66 of the molding tool 60 as shown in FIGS. 5-7.
The tracking system 20 includes at least one pair of guide rollers 72 mounted
to the end of at least one of the legs 74 of the base frame 14 of the carriage and
proximate to wheel 70. The pair of guide rollers 72 are space apart so that they
engage both sides of rail 62 and traverse along the axis of the rail 62. A second pair
of guide rollers 72 may be mounted to a second leg 74 on the same side of the base
frame proximate to the second wheel 70. The guide rollers 72 are coordinated with
the molding tool to provide definitive position of the carriage 10; provide proper twist
of the carriage 10 to mirror that of the molding tool 60; and maintain contact of the
carriage 10 to the molding tool 60 along the entire length of the molding tool.
Tracking guide rollers 72 also help to eliminate pull-off of the carriage resulting from
forces needed to propel the carriage along the molding tool.
In one alternative embodiment, the one or more rails are positioned under the
molding tool, rather than on the surface of the molding tool. In another alternative
embodiment, a separate rail is not used to guide the carriage. Instead, the molding
tool surface itself incorporates key features that are tracked by the carriage so as to
assure the proper placement of the prepreg material.
The compaction roller 48 exerts a compressive force to the prepreg tape by
contacting the top surface of the structural composite being laminated as the tape is
deposited on the molding tool. The compaction roller 48, made up of a plurality of
thin heavy, contiguous disks 50, is able to conform to the contours of the surface of
the molding tool 64, and in particular, is conformable to the concave portion 66 of the
molding tool so as to reduce the tendency of the tape to wrinkle when applied to the
concave (or convex) portions of the molding tool surface. With the compaction roller
48, the prepreg tape can be applied to molding tool surfaces having areas of varying
degrees of concave curvature, areas having varying degrees of convex curvature
and areas that are flat. The prepreg tape any also be applied along a non-linear
path on the molding tool surface.
Referring to FIG. 7, the upper frame 12 is rotatably secured to base frame 14
by turntable 76, which enables rotating the prepreg material by 180 degrees without
removing the dispensing carriage 10 from the molding tool 60. The turntable 76
allows the prepreg material to pass through the center of the apparatus 10 during the
dispensing operation. The locking member 78, when engaged, prevents rotational
movement of the upper frame 12 relative to the base frame 14, and establishes the
proper location of the prepreg spool for each direction of dispensing on the molding
tool 60.
The apparatus of the present invention may further include means for guiding
the prepreg lay down to assure controlled fiber alignment. The operation of the
carriage assembly 10 may be controlled by a controller (not shown). For example,
the carriage may be connected to a controller that is configured to control the
placement of the prepreg tape, the tension on the tape, the direction in which the
prepreg tape is applied to the surface of the molding tool and the speed at which the
prepreg tape is laid down.
The carriage assembly 10 may apply the prepreg material tape starting from
either end of the molding tool 60 and may start and stop according to predetermined
ply locations. A cutter may be used to automatically cut the ply. In one embodiment,
the carriage assembly 10 may include a laser guide (not shown) for determining the
ply locations.
In one embodiment, the carriage assembly may be removably coupled to a
spool loading station.
In another aspect of the invention, there is provided an apparatus that
includes a slitter and accumulator, the apparatus capable of laying down strips of
prepreg material formed from a wide prepreg tape product for a structure having inplane
curvature, while significantly reducing the effects of wrinkling on the inner
radius. The initial width of the prepreg tape product may be in the range of about 12
inches (30.5 cm) to about 60 inches (152.4 cm).
When building up a composite structure from prepreg tapes, the tapes are
usually laid down in straight line directions. Because the tape is being unrolled from
a single spool, the fibers cannot stretch in the lay-down process and cannot slide
relative to one another. As a result, these prepreg tapes cannot be laid down in an
in-plane curvature geometry without creating wrinkling or puckering on the inner
radius.
Referring to FIG. 15A, a prepreg tape 200 dispensed using conventional
apparatus in a linear direction has a plurality of aligned reinforcing fibers 202 that are
pre-impregnated with a polymer. When the tape 200 is applied to a flat, linear
surface, the tape lies smoothly without wrinkling or puckering. FIG. 15B illustrates a
prepreg tape 200 dispensed in a non-linear, curved direction using conventional
apparatus. The tape 200 lies smoothly along the outer edge 204 of the curved
surface. However, along the inner edge 206, wrinkles 208 are formed.
FIG. 16 is a photograph of a 7 inch (17.8 cm) wide strip of prepreg laid down
to an in-plane radius of curvature of 130 feet (39.6 m) using a conventional
apparatus. The wrinkling and puckering 208 on the inner radius 206 can be clearly
seen. This wrinkling creates a loss of orientation of fiber direction and results in loss
of composite mechanical properties in this region. Carbon fiber composites are
particularly sensitive to loss of compression strength due to such loss of fiber
orientation.
Referring to FIGS. 8-1 0, another exemplary embodiment of the prepreg tape
dispensing apparatus of the present invention is illustrated. The apparatus
comprises a movable carriage 0 that includes a spool holding assembly 16 for
demountably holding a spool 80 of a continuous web of prepreg tape material 82
having a wide width. As previously described, this embodiment of the carriage 10
includes an upper frame 12 rotatably mounted to a base frame 14. Mounted on the
upper frame 12 are a prepreg spool holding assembly 16 and a compaction
assembly 18 . The base frame 14 includes a tracking system 20 to precisely place
the prepreg material on the surface of the molding tool. The carriage assembly 10
includes turntable 76 which enables upper frame 12 to rotate relative to base frame
14, such that application of the prepreg tape material on the molding tool 60 may be
carried out in the forward direction and in the reverse direction.
As the prepreg material tape 82 is unwound from the spool 80, it is advanced
to a slitter 90 where it is slit into a plurality of strips 84 of prepreg material. The slitter
90 may include, for example, a plurality of stationary knives 92 or rotary knives. The
number of strips and the width of the individual strips 84 depend on the degree of
non-linearity of the surface of the molding tool 60 to which the strips 84 are applied.
For example, the strips 84 may be uniform in width or may have different widths to
accommodate the non-linear path of the molding tool 60. While the description of
the apparatus herein refers to a molding tool, it is to be understood that the prepreg
material may be applied to the surface of a mold, mandrel, or any other surface used
to form the composite structure in the prepreg dispensing operation.
In another embodiment, the strips 84 are slit during manufacture of the wide
prepreg web prior to being wound on a single spool. The spool 80 of pre-slit strips is
then mounted on the spool holding assembly 16 .
The carriage 10 includes a mechanism for taking up the difference in length of
the individual strips 84 resulting from the non-linear path of the molding tool 60. In
one embodiment, an accumulator 94 is used. Accumulator 94 includes a plurality of
rollers 96, each strip of prepreg 84 having an associated roller that is independently
extendable and retractable as needed to manage the excess length of the individual
strip resulting from the non-linear path on the molding tool 60. The accumulator
rollers 96 maintain tension in the individual strips 84 so that the individual strips 84
are smoothly applied to the molding tool 60. Extension and retraction of the rollers
96 of the accumulator 94 may be effected by a plurality of actuators 98 coupled to
the rollers 96. In one embodiment, the actuators 98 include air cylinders.
Referring to FIG. 11, the carriage 10 includes a tensioning system 38 that
includes a brake disk 32 fixed to spindle 22, and pneumatically actuated brake pads
100 that apply friction to the disk 32 under programmed control.
Referring to FIGS. 12 and 13, as the prepreg material 82 is unwound from the
spool 80, it is advanced to a slitter 90 where it is slit into a plurality of strips 84 of
prepreg material. The prepreg strips 84 travel over the rollers 96 of the accumulator
94, the path each strip independently controlled to manage any excess length of the
individual strip resulting from the non-linear path on the molding tool 60 to which the
strip is applied. From the accumulator rollers 96, the strips proceed to guide rollers
102 which position the strips near the surface of the molding tool. The compaction
roller 48 contacts the prepreg strips 84 and applies compaction pressure to
compress the prepreg strips 84 to the surface of the molding tool 60. The surface of
the molding surface 60 may include concave and/or convex areas having varying
degrees of curvature, and/or flat areas. Although the path of the individual prepreg
strips 84 on the surface of the molding tool may be nonlinear or curved, the
apparatus 10 is able to lay down the strips with little or no wrinkling of the prepreg
layers and/or gaps between the strips on the mold.
FIGS. 12-14 illustrate the steps involved in the positioning the tape on the
molding tool. Before being slit into strips 84, the tape 82 is guided by the threading
guide 104 along the tape path as shown in FIG. 12, with the slitter 90 inactivated.
The tape 82 is clamped or held to the surface of the mold tool 60. The slitter 90 is
then activated and the carriage 10 begins to move forward (in the direction indicated
by the arrow), pulling the tape 82 until the slit portion of the tape (i.e., the strips 84)
have extended past the compaction roller 48. The tape 84 is then cut laterally and
the carriage 10 advances out of the way so the tape just laid down can be pulled up
and discarded. The carriage 10 then moves to the programmed start position for the
next layer to be applied, and the compaction roller 48 is lowered to begin adhering
the prepreg strips 84 to the molding tool surface 64. From this point, the prepreg
strips 84 are aligned by the crowned accumulator rollers 96 and the crowned guide
roller 102. As the carriage 10 transitions from straight portions of the molding
surface 64 to swept portions, or from one radius of sweep to another, the cross
carriage 106 is shifted laterally by the cross carriage drive motor 104 to keep the
center of the tape aligned with the center of the molding surface. In this
embodiment, the amount of shift is previously input as offset data points into a table
in the controller 112. This same cross carriage 106 is used to move the carriage an
additional or lesser distance as needed to track the tape 82 coming off the spool 80,
as detected by the web edge sensor 110 . This is done to provide a degree of
compensation for tape not evenly wound on the spool 80, or tape 82 that has shifted
on the spool 80 during transport.
The operation of the carriage assembly may be controlled by a controller 112 .
For example, the carriage 10 may be connected to a controller 112 that is configured
to control the placement of the prepreg tape 82 or strips 84, the tension on the tape
or strips, the direction in which the prepreg tape or strips are applied to the surface of
the molding tool 60 and the speed at which the prepreg tape or strips are laid down.
The carriage assembly 10 may apply the prepreg material tape 82 or strips 84
starting from either end of the molding tool 60 and may start and stop according to
predetermined tape or strip locations. A cutter, such as an ultrasonic knife (not
shown) may be used to automatically cut the tape or strips. In one embodiment, the
carriage assembly may include a laser guide for determining the tape or strip ply
locations.
The prepreg tape material 82 on the spool 80 may have a liner or backing
layer adhered to the prepreg tape 82. In one embodiment, the liner or backing layer
of the prepreg material is removed from the underside of prepreg web prior to laying
down the tape 82 or individual strips 84 of prepreg material, and is taken up on liner
take-up roll. In one embodiment (not shown), the prepreg material web 82 includes
a liner on the upper surface of the web that is removed prior to laying down the web.
The carriage assembly may further include means for detecting incomplete removal
of the liner or backing from the prepreg material web.
In one embodiment, the carriage assembly 10 may be removably coupled to a
spool loading station.
EXAMPLE
A four wheeled cart was constructed to hold a spool of prepreg material
having an outside diameter of up to 32 inches (81 .3 cm) and an inside diameter of 12
inches (30.5 cm), and having a length of approximately 1800 feet (549 m). A 600
miNinneter wide web of prepreg was slit into twelve strips of 2 in. (50.8mm) in width
with stationary knives mounted on the cart.
Approximately three spools of prepreg material were used to construct a wind
turbine spar cap. The spools were loaded onto the cart by an overhead crane or
forklift.
The problem of wrinkling was reduced by laying down narrower prepreg strips
from a given radius of curvature. An analysis of this was done for the 130 feet (40
meter) radius of curvature and is shown in Table 1 below. As can be seen for this
particular analysis, when strips are approximately 2.0 inches (5.0cm) wide, the
wrinkling area is reduced to approximately 8% of the baseline for 24 inch (61 cm)
wide prepreg strip.
Table 1
Wrinkle area for a 600mm wide strip on a 40 meter radius
number of strips av. Width mm av width in. wrinkle area %
1 600.00 23.62 4 .181 100.0 Baseline
2 300.00 11.81 2.090 50.0
3 200.00 7.87 1.394 33.3
4 150.00 5.91 1.045 25.0
5 120.00 4.72 0.836 20.0
6 100.00 3.94 0.697 16.7
7 85.71 3.37 0.597 14.3
8 75.00 2.95 0.523 12.5
9 66.67 2.62 0.465 11.1
10 60.00 2.36 0.418 10.0
11 54.55 2.15 0.380 9.1
12 50.00 1.97 0.348 8.3 Target
13 46. 15 1.82 0.322 7.7
14 42.86 1.69 0.299 7.1
15 40.00 1.57 0.279 6.7
16 37.50 1.48 0.261 6.3
17 35.29 1.39 0.246 5.9
18 33.33 1.31 0.232 5.6
19 3 1.58 1.24 0.220 5.3
20 30.00 1.18 0.209 5.0
2 1 28.57 1.12 0.199 4.8
22 27.27 1.07 0.190 4.5
23 26.09 1.03 0.182 4.3
24 25.00 0.98 0.174 4.2
25 24.00 0.94 0.167 4.0
26 23.08 0.91 0.161 3.8
27 22.22 0.87 0.155 3.7
28 2 1.43 0.84 0.149 3.6
29 20.69 0.81 0.144 3.4
30 20.00 0.79 0.139 3.3
3 1 19.35 0.76 0.135 3.2
32 18.75 0.74 0.131 3.1
33 18. 18 0.72 0.127 3.0
34 17.65 0.69 0.123 2.9
35 17. 14 0.67 0.119 2.9
Table 1 cont.
number of strips av. Width mm av width in. wrinkle area
36 16.67 0.66 0.116 2.8
37 16.22 0.64 0.113 2.7
38 15.79 0.62 0.110 2.6
39 15.38 0.61 0.107 2.6
40 15.00 0.59 0.105 2.5
4 1 14.63 0.58 0.102 2.4
While this exemplary lay-up could be achieved by using a prepreg product
that consisted of 2-inch (5.1 cm) wide strips, production and packaging of individual
prepreg strips would add significant cost over starting with a 24 inch (61 .0 cm) wide
prepreg product on a single spool.
The apparatus and process of the present invention is particularly useful for
the construction of wind turbine components. However, the apparatus and process
can also be used for, for example, in the construction of structural and aerodynamic
components for airplanes, helicopters, automobile bodies, rail cars, marine crafts
and the like.
Although the invention has been shown and described with respect to a
certain embodiment or embodiments, it is obvious that equivalent alterations and
modifications will occur to others skilled in the art upon the reading and
understanding of this specification and the annexed drawings. In particular regard to
the various functions performed by the above described elements (components,
assemblies, devices, compositions, etc.), the terms (including a reference to a
"means") used to describe such elements are intended to correspond, unless
otherwise indicated, to any element which performs the specified function of the
described element (i.e., that is functionally equivalent), even though not structurally
equivalent to the disclosed structure which performs the function in the herein
illustrated exemplary embodiment or embodiments of the invention. In addition,
while a particular feature of the invention may have been described above with
respect to only one or more of several illustrated embodiments, such feature may be
combined with one or more other features of the other embodiments, as may be
desired and advantageous for any given or particular application.

Claims
1. A carriage to apply a resin impregnated web to the contoured surface of
molding tool for a wind blade spar cap, the carriage comprising:
an upper frame mounted to a base frame, the upper frame having mounted
thereon:
a spool holding assembly for holding a spool of resin impregnated web
wound thereon,
a web compaction assembly comprising a compaction roller configured
to conform to concave and convex portions of the surface of the molding tool for
compacting the resin impregnated web onto the surface of the molding tool, and
a web tensioning system for exerting tension on the resin impregnated
web;
the base frame comprising:
a plurality of wheels mounted on the base frame and supporting the
carriage, the wheels engaging the surface of the molding tool for propelling the
carriage along the contoured surface of the wind blade spar cap molding tool; and
a tracking system for tracking the surface of the molding tool, the
carriage reciprocally movable with respect to the contours of the surface of the
molding tool.
2. The carriage according to claim 1 wherein the spool holding assembly
comprises an alignment system for laterally aligning the spool of prepreg web
relative to the surface of the molding tool.
3. The carriage according to claim 1 or 2 wherein the compaction roller
comprises a plurality of contiguous disks supported on an axle, the disks having a
central bore diameter that is greater than the outer diameter of the axle.
4. The carriage according to any one of claims 1-3 wherein the upper frame is
rotatably mounted on the base frame.
ZOLTPOI 04WOA
- * 5. The carriage of claim 4 wherein the upper frame rotates at least 180" on the
base frame to permit changing the direction of application of the resin impregnated
web on the surface of the molding tool.
6. The carriage of any one of the preceding claims further comprising a turntable
coupled to the upper frame and the base frame to permit rotation of the upper frame
on the base frame.
7. The carriage of any one of the preceding claims wherein the web tensioning
system comprises an actuated disk brake.
8. The carriage of any one of the preceding claims wherein the molding tool
comprises at least one rail and the tracking system comprises at least two guide
rollers that engage the at least one rail.
9. The carriage of any one of the preceding claims wherein the width of the resin
impregnated web is within the range of about 11.5 inches (292 mm) to about 60
inches (152.4 cm).
10. The carriage of any one of the preceding claims further comprising a slitter for
slitting the resin impregnated web lengthwise into a plurality of strips, the slitter
mounted on and rotatable with the upper frame.
- 11. The carriage of claim 10 wherein the slitter comprises a plurality of knives.
12. The carriage of claim 10 or 11 wherein the width of the plurality of strips of
resin impregnated web is uniform.
13. The carriage of claim 10 or 1 I wherein the width of the plurality of strips of resin
impregnated web is non-uniform.
14. The carriage of any one of claims 10-1 3 further comprising a plurality of
accumulator rollers disposed downstream of the slitter, each accumulator roller being
independently activatable for accumulating and de-accumulating a portion of a
I respective strip of resin impregnated web, the accumulator rollers mounted on and
rotatable with the upper frame.
15. The carriage of any one.of the preceding claims further comprising a
controller configured to control at least one of:
the placement of the resin impregnated web on the surface of the molding
tool; : .
the tension exerted by the tensioning system on the web;
the direction in which the web is applied to the surface of the molding tool;
and
the speed at which the web is applied to the surface of the molding tool.