In general, his invention relates to machines which lay strips of
composite material onto a surface, and particularly but not exclusively, where
it is desirable to compact strips having tails, i.e., trailing sections of material
which are less than full strip width. In particular, this invention relates to
compaction of composite tape by a compactor having at least two levels of compaction
In the field of advanced composites, where a composite tape of fibre
reinforced resin is laid on a tool to create laminated structures such as aircraft
parts, it is necessary to lay progressive runs of tape at angles other than 90°
and 0° with the tool. When laying cross plies, for example at 45°, it is often
necessary to cut the end of the tape strip at some angle other than 90° with the
tape length, and a problem may arise when a primary compacting member spans adjacent
pieces, which are carried on a backing.
US-A-4557783 addresses the problem of tail compaction in a composite
tape laying machine. The machine and compaction device are shown herein as Prior
Art Figures 1, 2a, 2b, and 2c. The entire disclosure and teaching of the '783 patent
is expressly incorporated herein by reference. Prior art Figure 1 depicts a high
rail gantry tape laying machine 10 wherein a tape laying head 11 is transported
coordinately on horizontal side rails 12 and transverse gantry rails 13 under a
program commanded by a numerical control (NC) unit 14. A contoured tape laydown
surface 15, or tool, is positionable with respect to the tape laying head 11 to
form laminated composite structures. The tape laying head 11 comprises, in part,
a main frame 16 supporting a tape supply reel 17. The supply reel 17 carries a
tape structure 18 comprising a filamentous composite tape and a paper backing.
The tape structure 18 is trained under a tape compactor unit 19 and backing is
accumulated on a take-up reel 20, in a manner well-known in the art. The tape laying
head 11 is movable along a vertical, or Z-axis 21 to adapt to changing tool heights
along the tape path, and the entire tape head 11 is rotatable around the vertical
axis 21. Figure 2a depicts a schematic of the tape laying head 11 movable in a
direction "X" with respect to a tool 22. The tape laying head 11 has a supply reel
17 which feeds out a tape structure 18 comprising a composite tape 23 releasably
attached to a backing 24 such as a paper strip. The tape structure 18 feeds through
a cutter unit 25 and tape guide chute 26 to its lowermost position, adjacent the
tool 22, where it then passes under a presser shoe or primary compactor 27 of the
tape compactor unit 19. As the tape 23 is pressed against the laydown surface 28
of the tool 22, the backing 24 is separated and pulled onto the take-up reel 20
on the head 11. Since the compactor 27 will ultimately see a tape tail 29, as depicted
in Figure 2b, and since the compactor 27 presses against the backing 24 in order
to force the tape 23 against the laydown surface 28, it is obvious that the following
section 30, complementary to the tail 29, would also be stuck down if there were
only one compactor 27. To obviate this difficulty in handling the tail 29, the
prior art tape head 11 includes a tail compactor 31, which is a roller 32, carried
on a pivotable bell crank 23. The bell crank 23 is swung from a pivot joint 34
on the head 11 by a cylinder 35, reacting against the head 11, to drive the tail
compactor 31 against the tape 23 in the manner shown in Figure 2c. The tail compactor
31 is located at a spot between the backing 24 and the previously laid tape 23a,
so that it contacts only tape 23 when swung into the "down" position. Through linkage
36 attached from the bell crank 33 to the primary compactor 27 and to a backing
guide 37, the downward stroke of the tail compactor 31 with respect to the tape
laying head 11 forces the primary compactor 27 and entire tape head 11 up, away
from the laydown surface 28, and the linkage 36 also moves the backing guide 37
into a position to help steer the backing 24 on its way to the take-up reel 20.
Certain features are noteworthy: Since the primary compactor is affixed
to the tape head, the primary compaction force is provided by the head itself.
And, since the tail compactor is thrust into position by reaction against the tape
laying head, the tail compaction force is likewise provided by the head itself.
Additionally, the primary and tail compactors, as depicted, are spaced from one
another along a horizontal plane, and this may prohibit application of the head
to certain contoured parts which deviate substantially from a flat surface, along
the tape length.
US-A-4954204 teaches a presser member for contoured surfaces, and
the entire disclosure and teaching of the '204 patent is expressly incorporated
herein by reference. The '204 device is depicted herein as Prior Art Figures 3,
4, 5a, 5b, and 5c. With reference to Prior Art Figure 3, the '204 patent teaches
a presser member 38 which is affixed to the bottom of a tape laying head 11, as
a primary compactor, but wherein the primary compaction force is obtained from
an actuator 39 within the device itself; thus the presser member elements move
with respect to the tape head 11. The presser member elements comprise a shoe
plate stack 40, i.e., plurality of adjacent shoe plates 41 of common cross-section
(see Figure 4), which may adapt to contours occurring across the tape strip 23.
The presser member 38 is a four-bar linkage of the double-slider type, where a
horizontal slider 42 is connected by a control link 43 to a vertical slider (the
shoe plate stack 40). The presser member 38 has a housing 44, quarter-rounded at
its lower rear surface and hollowed out to accommodate detail pieces. The top of
the housing supports a centrally located air cylinder 45, having a piston rod 46
extending frontwardly, i.e., to the right of the figure. Immediately adjacent the
front of the cylinder 45 is a pair of parallel guide rods 47a,b, one at each side
of the assembly. The horizontal slider 42 rides on the guide rods 47a,b, and the
end of the piston rod 46 is affixed to the slider 42.
Figure 4 shows the shoe plates 41 in relation to the control link
43 and a control rod 48 which extends through the shoe plates 41. At the interior
of the housing 44 is the actuator 39 for biasing the plates 41 downwardly, away
from the housing 44. The actuator 39 is a closed bladder spring, where a chamber
49 is faced with a flexible membrane 50 which contacts the top edges of the shoe
plates 41. Pressurized fluid is ducted into the chamber through a port 51 to load
the compliant membrane 50 against the shoe plates 41.
Figure 5a is a diagrammatic view of the elements of Figure 3, showing
the quarter-round housing 44 supporting the vertically movable shoe plate stack
40, with a latch finger 52 "up" and the slider 42 moved to the right against the
latch finger 52. The control link 43 is shown connected to the control rod 48
which evens out, or "nulls" all plates at a known dimension, Z'. The downward biasing
force provided by the membrane 50 is depicted as a bladder spring 53 reacting against
the top edge 51 of the shoe plates 41. The position of the elements in Figure 5a
is used for programming all vertical, or Z-axis dimensions, providing a known point
from which the shoe plates 41 may float up and down. Figure 5b depicts elements
of Figure 5a in an alternate position, where the latch finger 52 is "down" and
the slider 42 is moved leftwardly to the fully-retracted position. This position
of the presser member 38 is used for compacting a tape strip 23 against the tool
laydown surface 28. The control link 43 has moved the horizontal control rod 48
to an intermediate position within the shoe plate slot 54; the shoe plates 41 are
free to float on tool contours as the bladder spring 53 biases the entire shoe
plate stack 40 against the tape 23. Figure 5c depicts the latch finger 52 retracted,
and the slider 42 now fired to the fully-advanced position, all the way to the
right. The control link 43 now pulls the control rod 48 to a new raised position,
thus fully-retracting the vertically-movable shoe plates 41 upwardly into the housing
44, compressing the biasing bladder spring 53. This position permits the use of
auxiliary equipment, such as a tail compacting roller 55.
The present invention provides a compactor assembly for composite
material, and method of use, wherein a primary compactor is independently powered
with respect to a machine head and combined with a secondary compactor which is
likewise independently powered with respect to the head, and where at least one
of the compactors may be operated with at least two different levels of compaction
The present invention also provides a composite tape strip compactor
assembly, and method of use, in which a main compactor is adaptable to contour
changes occurring across the tape strip and a tail compactor is capable of tail
compaction on surfaces deviating substantially from a flat plane along the tape
length, and where at least one of the compactors may be operated with at least
two different levels of compaction force.
The present invention further provides a compactor assembly for composite
tape, and method of use, in which a main compactor is utilized for laying essentially
a full-width tape strip at a tape laydown point defined with respect to a tape
laying head, and in which the main compactor is displaced by a tail compactor which
may finish laying the tail of the tape strip at the tape laydown point, and where
at least one of the compactors may be operated with at least two different levels
of compaction force.
The present invention further provides a compactor assembly for composite
tape, and method of use, wherein main compaction and tail compaction occur at substantially
the same point with respect to the tape laying head which carries the compactor
assembly, and where at least one of the compactors may be operated with at least
two different levels of compaction force.
The present invention further provides a compactor assembly for composite
tape, and method of use, wherein primary tape strip compaction and tail compaction
are independent of tape laying head movement and are provided by the same actuator,
carried by the tape laying head, and where at least one of the compactors may be
operated with at least two different levels of compaction force.
The present invention further provides a compactor assembly for composite
tape, and method of use, in which linkage is utilized for simultaneously switching
positions of the main compactor and tail compactor with respect to a tape laydown
point, and where at least one of the compactors may be operated with at least two
different levels of compaction force.
The present invention further provides a method for compacting composite
materials, comprising the steps: placing composite material on a support surface;
positioning a compaction frame proximal said support surface; providing a compaction
element on said frame between said frame and said material; providing a fluid actuator
between said element and said frame; porting pressurized fluid into said actuator;
applying a first compaction force to said material with said compaction element;
varying the pressure of said pressurized fluid; and applying a second compaction
force to said material with said compaction element.
There will now be given a detailed description, to be read with reference
to the accompanying drawings, of a tape laying machine and method of laying composite
tape which have been selected to illustrate the invention by way of example.
In the accompanying drawings:
- Figure 1 is a perspective view of a prior art tape laying machine.
- Figure 2a is a side elevational view of a prior art compactor assembly performing
a main compaction operation.
- Figure 2b is a plan view of a prior art tape strip having an angled tail.
- Figure 2c is a side elevational view of the prior art compactor assembly of
Figure 2a, performing a tail compaction operation.
- Figure 3 is a side elevational view of a prior art compactor.
- Figure 4 is a front elevational view, in partial section, taken along the
- line 4-4 of Figure 3. Figures 5a, 5b, and 5c are diagrammatic views of the
prior art compactor of Figure 3.
- Figure 6 is a side elevation of a tape compactor assembly of the tape laying
machine which is the preferred embodiment of this invention.
- Figure 7 is a front elevational section, taken along the line 7-7 of Figure
- Figure 8 is a rear view, taken in the direction of arrow 8 of Figure 6.
- Figure 9 is an elevational section, taken along the line 9-9 of Figure 6.
- Figure 10 is a sectional view, taken along the line 10-10 of Figure 6.
- Figures 11a, 11b, and 11c are diagrammatic views of the tape compactor assembly
of Figure 6.
- Figure 12 is an elevational section, taken along the line 12-12 of Figure 11b.
- Figure 13 is an elevational section, taken along the line 13-13 of Figure 11c.
- Figure 14 is a side elevational view of a tape compactor assembly.
- Figure 15 is an elevational section through a tape compactor, illustrating
a work surface having a valley.
- Figure 16 is an elevational section through a tape compactor, illustrating
a work surface having a peak.
- Figure 17 is a diagrammatic view, in perspective, showing a compaction roller
on a tape tail.
- Figure 18 is a graph plotting compactor air pressure vs. tape tail length.
- Figure 19 is an elevational section through a segmented compactor for composite
It should be noted that certain attitudinal references are employed
herein, e.g., "horizontal", "vertical", and the like. Such references are only
for the convenience of the reader, and the machine structure is not so limited;
those skilled in the art will appreciate that the spatial ordinates of the machine
may be changed to suit a variety of tasks within the scope of the invention.
With reference to Figure 6, a tape head 60 is shown with an improved
tape compactor assembly 61 affixed to its bottom surface. The tape head 60 is
of a type which may be used with the tape laying machine 10 of Figure 1. The tape
compactor assembly 61 will move in a forward direction "X" with the tape head 60,
to the right of the figure, when laying tape 23, and the head 60 thus has a front
end 60a, at the right of the figure, and a rear end 60b to the left of the figure
The assembly 61 includes a housing 62 which is quarter-rounded at its lower rear
surface and hollowed out to accommodate detail pieces (not shown). The top surface
of the housing 62 has a frame 63 affixed thereto, which extends frontwardly. The
frame 63 serves as a mounting for an air cylinder 64, which has a piston rod 65
extending frontwardly. The frame 63 also supports a pair of parallel guide rods
66a,b, one at each side of the assembly 61, and a horizontal slider 67 rides on
the guide rods 66a,b and extends across the housing 62 from side-to-side (see also
Figures 7 and 8). The slider 67 is affixed to the piston rod 65.
The horizontal slider 67 has three specific positions:
- (1) fully-retracted, as in Figures 6 and 11a;
- (2) forwardly-advanced against a latch finger 68, as in Figure 11b; and
- (3) fully-advanced to the right with the latch finger 68 retracted, as in Figure
The latch finger 68 is powered in vertical directions by a compact
fluid cylinder unit 69 secured to the bottom of the frame 63. Each side of the
housing 62a,b has a vertical slider 70, constrained to move within a vertical track
71 along a vertical centerline 72 defined on the housing 62. Within the housing
62, immediately behind the vertical slider 70, is a main compactor 73. As shown
in Figure 9, the main compactor 73 comprises a shoe plate stack 74 for contacting
the backing 24 of a tape structure 18. The shoe plate stack 74 is a plurality of
parallel, wafer-like shoe plates 75 guided for vertical movement with respect to
one another within the housing 62. A vertical elongate slot 76 of common size
is provided in line through all of the plates 75, and a control rod 77 extends
horizontally, from side to side through all of the slots 76 and is affixed to the
vertical sliders 70. In the position shown in Figures 6,9, and 11a, the control
rod 77 is positioned approximately mid-way along the vertical slot 76 so it will
not interfere with compactor movement which may require the shoe plates 75 to
adapt to a variety of contours across the tape width. This is the normal tape laying
position. When it is desired to land the compactor 73 and tape 23 on a work surface
78, at the beginning of a tape laying run, the horizontal slider 67 is stopped
against the latch finger 68 as depicted in Figure 11b. In this position, the upper
edges 76a of the slots 76 will rest on the raised control rod 77, causing the bottom
edges 75a of the shoe plates 75 to be in line as shown in Figure 13. This position
is an alignment, or "null" position, setting the bottom edges 75a of the plates
75 at a known relationship to the machine coordinates, for programming purposes.
In order to provide a downward biasing force to all of the plates
75, a bladder spring 79 has been devised, in the manner of U.S. Patent 4,954,204,
wherein the housing 62 has a closed chamber 80 formed immediately above the shoe
plate stack 74. The chamber 80 includes a flexible membrane 81 extending across
the shoe plates 75, in contact with and spanning the top edges 75b. The chamber
80 is provided with an orifice 82 so that air or other fluid medium may be introduced
into the chamber 80 and, thus, pressurize the membrane 81 to provide a downward
biasing force to the entire stack of plates 75. The membrane 81 is yieldable, to
accommodate surface contour variances which will cause the plates 75 to shift vertically,
relative to one another, as the tape 23 is laid.
In the preferred embodiment, the air valve unit 82a (Figures 9, 15,
16) employed to pressurize the bladder spring 79 produces a pressure output which
varies in proportion to the magnitude of an electrical signal. Such a valve unit
is the Pneutronics VIP-FLEX Pressure Control unit, available from LDI Pneutronics
Corp., Hollis, NH 03049. Therefore, this valve unit 82 may be controlled in accordance
with an NC program to vary air pressure and consequent force directed against the
tape 23. As an example, compaction of full-width tape may be performed at a constant
pressure. Next, unit loading on a tapered tail may be kept constant by changing
the total downward force acting on the tail compaction roller; i.e., by varying
air pressure in accordance with the tail profile.
It will be appreciated that in some instances, it may be desirable
to supply only a fixed pressure to the bladder spring 79. It may also be desirable
to supply two alternative pressures to the bladder spring 79; a first pressure
for main compaction, and a second pressure for tail compaction.
With reference back to Figure 6, a flexible sheet or skid 84 is attached
to the front of the housing 62, and directed around the nose, or bottom edge 75a
of the shoe plates 75 to present a smooth surface against the backing 24. It may
be appreciated, however, that some embodiments may omit the skid 84. The skid
84 is guided around the quarter-round section, within a surface channel or relief
85, and is held taut by a strap 86. The strap 86 is affixed to the skid 84 and
tensioned by a coiling device 87 carried on the tape laying head 60. The tape
structure 18 is shown coming from the tape guide chute 26 to the tape lay-down
point 88 established by the intersection of the vertical centerline 72 and a horizontal
plane 89 defined on the work surface 78. At the tape laydown point 88, while the
head 60 continues moving to the right, tape 23 is deposited on the work surface
78, and the backing 24 is separated from the tape 23 and pulled upwardly against
the skid 84, while running to a take-up reel (not shown).
The roller 90 depicted in Figure 6 is a tail compactor, and is located
between the tape 23 and the backing 24, trailing the tape laydown point 88, in
the manner taught in U.S. Patent 4,557,783, Prior Art Figure 2a. The roller 90
is shown in its home position, swung all the way to the left.
A tail compactor is a secondary compactor used for compacting tape
of less than full width. The roller 90 is carried at one end of a first elongate
link 91, which is pivotally connected at its other end to the vertical slider 70
about a first horizontal pivot axis 92. The horizontal slider 67 has a depending
section 67a at each side of the housing 62 (see Figure 7) which extends approximately
midway down the housing 62, and a second elongate link 93 is pivotally connected
at one end to the horizontal slider 67 about a second horizontal pivot axis 94
while its other link end is pivotally connected to the first link 91 about a third
horizontal pivot axis 95 lying approximately midway between the ends of the first
link 91. The first link 91 also includes a cam follower 96 which extends horizontally
from the link 91 into a cam slot 97 provided on the housing 62 (see also Figure
10). The cam slot 97 governs the first link 91 and, consequently, movement of the
tail compaction roller 90 as the horizontal slider 67 is driven by the cylinder
64. The cam slot 97 is arcuate and upwardly arched, from its initial portion, thereafter
sloping downwardly towards the vertical slider 70. And, while the cam follower
96 is accurately guided within the cam slot 97 for most of the path, the end of
the slot 97 is relieved, as will be described later in connection with Figure 11c.
While the first and second links 91,93 under discussion are shown on one side 62a
of the housing 62, i.e., facing the viewer, it will be appreciated that there are
identical links 91,93 on the opposite side 62b of the assembly 61, and the tail
compaction roller 90 spans the first links 91, as shown in Figure 8.
Operation of the compactor assembly 61 may be appreciated by referring
to diagrammatic Figures 11a-11c.
Figure 11a depicts the elements of Figure 6, where the latch finger
68 is "down" and the slider 67 is moved leftwardly to the fully-retracted position.
In this position, the main compactor 73 or shoe plate stack 74 is biased against
a tape backing 24 which is being stripped from tape 23 laid to the laydown surface
78, and the position of the vertical slider 70 and its control rod 77 is such that
the rod 77 will not hinder vertical float of the plates 75 (see also Figure 9).
The bladder spring 79 biases the entire shoe plate stack 74 against the backing
24 and tape 23, and the shoe plates 75 can float in compliance with contour variances
occurring across the tape width.
Figure 11b depicts the housing 62 with the latch finger 68 "up" and
the horizontal slider 67 moved to the right, against the latch finger 68. In this
position, the vertical slider 70 is driven upward slightly so that its control
rod 77 evens out, or "nulls" all plates 75 at a known dimension, Z' (see also Figure
12). The position of the elements in Figure 11b is utilized for programming all
vertical, or Z-axis dimensions. Figure 11c depicts the latch finger 68 "down",
and the horizontal slider 67 now fired to the fully-advanced position, all the
way to the right. The vertical slider 70 is now driven to a new raised position
where its control rod 77 drives the vertically-movable shoe plate stack 74 to a
fully-retracted upward position into the housing 62, compressing the bladder spring
79 (see also Figure 13). The skid 84 will follow along with the stack 74. Simultaneous
with this movement of the vertical slider 70, in response to horizontal slider
stroke, the first elongate link 91 is swung to a nearly vertical position, governed
through most of its movement by the cam follower 96 travelling in the cam slot
97, so that the tail compaction roller 90 will be switched into the region of the
tape laydown point 88, previously occupied by the now-retracted main compactor
73 (shoe plate stack 74). The linkage, coupled with guidance provided by the cam
follower 96, insures that the tail compaction roller 90 will move along a path
which will not interfere with the substantial slope (approximately 15°) of the
work surface 78 with respect to the horizontal plane 89. With reference to Figure
13, the tail compaction force is accomplished by the same bladder spring 79 which
provides the main compactor force. The compressed bladder spring 79 attempts to
drive the control rod downward along with the vertical slide 70, and the vertical
slide 70 in turn, drives the first elongate link 91 and roller 90 downward against
the tape tail 23a. The sides 97a,b of the cam slot 97 are slightly flared for clearance
(see also Figure 14) when the cam follower 96 is positioned as in Figure 11c, so
the first link 91 and roller 90 may move vertically against the tail 23a.
Thereafter, as the tape head 60 is lifted from the work surface 78
in anticipation of another tape laying run, the horizontal slider 67 is retracted
to the left, causing the tail compaction roller 90 to swing back out to its home
position, and permitting the main compactor 73 (shoe plate stack 74) to descend.
Figures 6-9 depict an ideal situation for the invention, where it
is assumed that the vertical slide 70 will move upward easily when the horizontal
slide 67 is actuated. It is further assumed that the cam follower 96 moves without
shake in the cam slot 97. In actual practice, though, frictional forces are present,
and the cam slot 97 at each side 62a,b, of the housing 62 is manufactured with
clearance; therefore, to ensure quick action and smoothness, a practical embodiment
of the invention is further developed in Figure 14, where the following features
may be seen:
- 1. The cam slot 97 is formed into a cam plate 98 bolted to the sides 62a,b,
of the housing 62; this simplifies machining and heat treatment, as well as alignment
of the right and left side elements.
- 2. A spring-loaded plate 99, slidable on shoulder screws 100, spans the housing
62 and is biased downwardly by springs 101 guided on the shoulder screws 100. The
plate 99 contacts a roller 102 which is clevis-mounted within the first link 91,
just above the cam follower 96. The spring-loaded plate 99 keeps shake out of the
assembly 61 while the tail compaction roller 90 is in its home position, and provides
impetus for the first portion of its advancement to the tape laydown point 88.
- 3. The top portion of the vertical slider 70 is provided with a horizontal
stud 103 which carries an antifriction roller 104. A bracket 105 on the sides 62a,b
of the housing 62 supports a helper cylinder 106. The cylinder 106 has a short-stroke
piston rod 107 linked to a lever 108 pivotally-mounted to the bracket 105. The
lever 108 extends under the roller 104 and serves to provide an initial lifting
force for the vertical slide 70, to overcome friction as the horizontal slide 67
is actuated. Once moving, the mechanical advantage of the horizontal slide 67 over
the vertical slide 70 increases, and the assist provided by the lever 108 is no
longer needed. The piston rod 107, lever 108 and roller 104 are all outside of
the first link 91, to avoid interference.
- 4. The second link 93 is comprised of two link ends 93a,b, connected by a stud
109, threadably received therein, and a locknut 110 secures the assembly once the
proper dimension between the second and third pivot axes 94,95 has been established.
Those skilled in the art will appreciate that the vertical slide 70
may be provided with antifriction elements in certain applications. Similarly,
provision of antifriction elements within the various slides, pivot joints and
rollers herein, are deemed to be well within the ken of the machine designer.
It may be noted that, while the actuator for the main compactor 73
comprises a bladder spring 79, having a closed chamber with a membrane covering,
it is also anticipated that the membrane 81 may be omitted, and fluid pressure
may be applied directly against the top of the shoe plate stack 74 to bias the
stack 74 in a downward direction.
It is further contemplated that a resiliently faced element may be
substituted for the main compactor 73, and other devices may be substituted for
the tail compaction roller 90.
The sectional view depicted in Figure 15 shows certain elements of
Figure 9, wherein the main compactor 73, or shoe plate stack 74 is shown distributed
across a tape strip 200 laid in a valley 201 of a work surface 202. In general,
more compaction force is needed to compact the tape strip 200 into the valley 201,
than is needed to compact the tape strip 200 on a flat surface. In this case, therefore,
the valve unit 82a is modified by command from the NC unit 14 to port a higher
pressure P&sub1; into the bladder spring 79 than is required for normal flat laying
runs. As stated before, the air valve unit 82a receives a supply of air or other
fluid from a supply line 203, and is easily modulated or changed in response to
an NC program, since the machine programmer will be well aware of the tool contours
and tape strip placement requirements. As further illustration of the desirability
of having a programmable air pressure and consequent programmable compaction force
capability, Figure 16 depicts the elements of Figure 15 when changing to a profile
which has a peak 204 occurring across the tape width. Here, a lesser compaction
force is needed than is required to lay the tape strip 200 into a valley 201 per
Figure 15, and consequently, the valve unit 82a is managed by further instruction
from the NC unit 14 to reduce the pressure from that of Figure 15 to a reduced
The use of a main compactor 73 as in Figures 15 and 16, is not confined
to a machine of the kind described above (see Figure 1), but is adaptable to other
machines which apply composite material to a support surface; for example, a fibre
placement machine as depicted in U.S. Patent 5,022,952. The entire disclosure and
teaching of the '952 patent is herein expressly incorporated by reference, and
the term "tape laying" is used herein to be deemed to incorporate such fibre placement
Figure 17 discloses a sequence drawing, in perspective, of application
of a variable force tail compactor 205 to a linearly tapering tail 206 of a composite
tape strip 207. In this case, for illustration purposes, five positions are shown
along the tape tail 206 where it is desired to maintain a constant unit loading
on the tail material with a tail compaction roller 90 which extends for the full
width of the tape 207. In this case, therefore, the force applied to the roller
90 should decrease linearly from the beginning 208 of the tape tail 206 to the
end 209. The five positions depicted illustrate force levels F&sub1;, F&sub2;,
F&sub3;, F&sub4; and F&sub5;, which correspond to pressure levels P&sub1;, P&sub2;,
P&sub3;, P&sub4; and P&sub5;. A pressure distribution graph 210 is shown in Figure
18, where the pressure varies linearly for the length of the tail, "L". Thus, the
valve unit 82a is programmed for variable pressure along the tail 206. With reference
back to Figures 9 and 13, the tail compaction force is provided to the roller 90
by the bladder spring 79, pressurized by the valve unit 82a.
The application of a variable force compactor to a variety of composite
materials and machines is further facilitated by a reference to U.S. Patent 4,869,774,
which discloses a segmented compactor 211 which finds application in both tape
laying and fibre placement machines. The entire disclosure and teaching of the
'774 patent is expressly incorporated herein by reference. Figure 19 depicts a
segmented compactor 211 from the '774 patent, which has a reference roller 212
at its centre position flanked by adjacent sliding rollers 213 which may move relative
to the fixed reference roller 212. In this case, the actuator 214 for pressurizing
the movable rollers 213 is also supplied with air from the valve unit 82a, and
regulated by a numerical control program within the NC unit 14.
While the invention has been shown in connection with a preferred
embodiment, it is not intended that the invention be so limited. Rather the invention
extends to all such designs and modifications as come within the scope of the appended
The features disclosed in the foregoing description, or the following
claims, or the accompanying drawings, expressed in their specific forms or in
terms of a means for performing the disclosed function, or a method or process
for attaining the disclosed result, as appropriate, may, separately or in any combination
of such features, be utilised for realising the invention in diverse forms thereof.