Note: Descriptions are shown in the official language in which they were submitted.
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Method and Apparatus to Continuously Separate
Cut Pieces from Flexible Material
This application claims the benefit of United States Provisional
Application No. 60/677,244, filed May 3, 2005 and entitled Vacuum Roller.
BACKGROUND OF THE INVENTION
This invention relates to the field of selecting and removing pattern
pieces that have been severed or cut from a web or sheet of flexible material,
while the pattern pieces are still embedded within the web, both being
supported on a common surface.
This invention also relates to the field of vacuum rollers where one or
more said rollers are disposed along the path of an advancing web said rollers
being oriented such that each roller's axis of rotation is both orthogonal to
the
advance direction of the web and orthogonal to the surface normal of the web
and said rollers. are positioned such that the web travels around at least a
portion of the arc of each said roller.
This invention also relates to the field of steering and guiding webs,
tapes, sheets and conveyer belts both with uniform material properties, and
those with non-uniform material properties.
This invention also relates to the field of effecting or influencing a process
to be performed on a web, tape, sheet or conveyer belts where the level of
pressure on the web must be applied in an arbitrary programmed manner over
the material surface.
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The webs or sheets are normally comprised of films, laminates, fibers
woven materials or animal hides as are used in technical textiles, apparel,
furnishings, engineering membranes, composite materials such as tapes,
wovens that may be pre-impregnated with adhesives or liner material and
nanostructured compositions such as distributed or aligned carbon nanotubes
which may further be embedded in a polymer web or sheet. Semi rigid foils
and semi rigid sheet metal webs or pieces may also be manipulated with the
apparatus described here.
The web or sheet in which the pattern pieces are embedded is supported
on a planar, cylindrical, or curved surface. The vacuum roller axis may be in
relative translational motion to the material support surface. The vacuum
roller has its rotational axis orthogonal to the relative direction of travel
of the
material surface and orthogonal to the normal vector of the material surface.
The vacuum roller is rotating so that the surface of the vacuum roller
and the surface of the material are in registration (no relative motion).
Prior art vacuum roller designs present a variety of methods to achieve
the application of selective vacuum to a portion of the arc of a roller. This
arc
portion is to remain generally stationary with respect to the machine
configuration, such that as the roller rotates, its surface ports are
successively
ported to either vacuum, pressure or closed.
Most of these designs are intended to provide vacuum retention and
motion to a web or sheet of flexible material by "pulling" vacuum through the
surface of a roller into the hollow core of the roller. The core has a
rotating
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joint at one or both ends that allows the attachment of a non-rotating vacuum
hose to a remote vacuum pump or source.
In the prior art, the general design schemes provide for the "zoning" of
vacuum and or positive pressure to a portion of the arc of the roller. Vacuum
is ported to the roller surface to draw the web or sheet into intimate contact
with the roller surface. At a pre-determined position of rotation, usually
when
the sheet leading edge is tangent to another roller, the vacuum is switched to
a
positive pressure to "push" the sheet or web leading edge away from the
current roller onto the next roller or conveyer. These roller pressure
transitions
are effected at specific arc locations and are in effect across the length of
the
roller at any specific arc position.
The prior art vacuum roller systems lack the ability to selectively control
the presence of vacuum at each of the surface ports of the roller
independently
of one another. The prior art fails to provide a mechanism to permit roller
pressure transitions which do not either apply to an entire row of surface
ports
along the roller or to an entire ring of surface ports around the
circumference
of the roller.
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SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a fully
addressable vacuum/pressure roller. A vacuum roller for conveying a web or
sheet type material, comprises a rotatable roller having an external surface.
The rotatable roller has a plurality of bores there through, each of which
bores
terminates at a surface port in the external surface of the rotatable roller.
A
plurality of addressable valves are in fluid communication with the plurality
of
bores. The plurality of addressable valves is also in fluid communication with
both a vacuum source and a pressure source. A means for addressably
controlling the state of each of the plurality of valves is provided to
selectively
permit the fluid communication through a respective one of the bores between
the vacuum source or pressure source and a respective one of the surface
ports. One method to addressably control each of the plurality of valves is to
utilize a programmable controller programmed with software that performs the
switch sequencing and a data base or data file that the software accesses, the
data represents the desired state of each of the valves at all times and/or
positions during operation.
A valve assembly is provided for use in a rotatable vacuum roller having
an external surface and a plurality of bores there through, each of which
bores terminates at a surface port in said external surface of the rotatable
roller. The valve assembly comprises a plurality of addressable valves each of
which is in fluid communication with a vacuum source and a pressure source
and one of said surface ports. A means for addressably controlling the state
of
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each of the plurality of valves is provided to selectively permit the fluid
communication through a respective one of the bores between the vacuum
source or the pressure source and a respective one of the surface ports.
The present invention describes a vacuum roller that allows the
selective application of vacuum or pressure to any desired surface port around
the roller's circumference and along the roller's length. This is programmable
so that any selected surface port may have its state changed at any time
during
operation. This "porting" is dynamic. The addressable valve in fluid
connection
with each surface port cari be switched instantly while the roller is
rotating.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1A is a perspective view of a schematic of an apparatus in
accordance with an embodiment of the present invention.
Figure lB is a cross-sectional view of the roller shown in Figure 1A
taking along lines lB-1B.
Figure 1C is an enlarged view of a portion of the roller shown in Figure.
1B.
Figures 2A and 2B are perspective and top views respectively of an
example of pressure distribution along a single row of surface ports.
Figures 3A and 3B show a conveyorized, two axis cutting system that
incorporates an example of the system described herein.
Figures 4A and 4B show an addressable vacuum roller having an array
of surface ports in accordance with one example of the present invention.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning now to the drawings, and first with reference to Figures 1A, 1B,
and 1C, an apparatus according to an embodiment of the present invention is
shown generally by reference numeral 101. There is provided a fully
addressable vacuum/pressure roller. As used herein, the word "addressable"
refers to the identification of a location by an address or a name in order to
facilitate information transfer. The use of an addressable control mechanism
provides the ability to independently switch any single surface port (also
referred to as aperture) to either vacuum, pressure or off (closed) without
reference to the state of neighboring surface ports. Addressable control
enables a vacuum roller to function with precision and specificity
facilitating
for example picking up and releasing work pieces having complex shapes from
within a web or sheet.
Also, although the examples discussed herein include roller systems, it is
envisioned that the addressable controls may be incorporated in other endless
surfaces in circuitous motion applications including conveyorized belt systems
generally. The use of addressable valves can benefit this entire class of
moving
systems that move in a loop.
Returning again to Figures 1A, 1B and 1C, a Vacuum roller 101 for
conveying a web or sheet type material (Not Shown), comprises a rotatable
roller 102 having an external surface 103. The rotatable roller 102 has a
plurality of bores 104 there through, each of which bores 104 terminates at a
surface aperture or port 105 in the external surface 103 of the rotatable
roller
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102. The surface ports 105 may preferably be disposed in a grid pattern of
rows along the longitudinal direction of the rotatable roller 102 and rings
(or
columns) around its circumference. The rows are parallel to the axis of the
roller and perpendicular to the direction of rotation of the roller.
A plurality of addressable valves 107 are in fluid communication with the
corresponding plurality of bores 104. The plurality of addressable valves 107
is
also in fluid communication with a vacuum source 108. This is achieved by
having a vacuum manifold 109 inside a rotating roller. The vacuum manifold
may be non-rotating, but is usually an axis-symmetric coaxial tube that
rotates
with the rotatable roller 102 to provide both a vacuum manifold and act as the
primary structural support for the roller. A rotating slip joint is used at
the
end of the roller to allow fluid communication of the non-rotating vacuum
source 108 with the rotating roller's vacuum manifold 109.
It is preferable in an alternative embodiment to provide, in addition to
the vacuum source, a positive pressure source 110. The pressure source will
enable positive air pressure to be used to discharge a piece of web material
from the vacuum roller by progressively pushing the piece away as the web and
roller advance. In this embodiment, the plurality of addressable valves 107 is
also in fluid communication with a pressure source 110. This is achieved by
having a pressure manifold 111 inside a rotating roller. The pressure manifold
111 may be non-rotating, but is usually an axis-symmetric coaxial tube that
rotates with the rotatable roller 102 to provide both pressure and act as the
primary support for the roller.
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Vacuum and pressure are commuted from remote pumps (not shown)
and compressors (not shown) to the rotating vacuum manifold 109 and
pressure manifold 111 through rotating slip joints 112 located at the end of
the
roller shaft. This design provides for both angular and axial zoning of vacuum
or pressure to the external surface 103 of the rotatable roller 102.
Figure 2A shows a representative pressure distribution diagram along a
single row 206 of an addressable vacuum roller. The high pressure zones 201
show positive pressure intended to push away web portions that intersect row
206, the low pressure zones 202 show vacuum intended to retain web portions
that intersect row 206.
Successive rows would generally have different pressure distribution
profiles valving vacuum for example to ports that are in contact with portions
of the web that are to retained by the roller, positive pressure to portions
of the
web that are to be removed from the roller, and closing the valve where no
material is in contact with the roller (not shown).
Vacuum and pressure levels are shown on the diagrams with magnitudes
of - 200 mb for the vacuum and + 200 mb for the pressure. However, these are
shown as examples only. Appropriate levels would need to be investigated to
be compatible with the web or sheet material to be manipulated and to allow
the addressable vacuum roller to function as intended.
With reference to Figure 2A and 2B, the following example is by way of
illustration only and is not intended to be limiting. A vacuum roller can be
provided which is suitable for the handling of 48" wide plasticized vinyl webs
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for example 0.030" thick. The vacuum roller in the present example has an
outside diameter of 10.0 inches and an active length of 48.0 inches. The axial
port pitch of the surface ports is 2.0 inches which corresponds to 25 equally
spaced surface apertures or ports along the roller's axis, the circumferential
port pitch of the surface ports is about 1.6 inches, which corresponds to 20
equally spaced surface ports around the roller's circumference. The surface
speed at which the web would travel while passing around the rotatable roller
is 40.0 inches/second. With these specifications, the rotatable roller would
have 500 surface ports. A programmable controller suitable for controlling the
embodiment of the invention which selectively provides both vacuum and
pressure in the rotatable roller would require 1000 output switches, 500 two
state switches to select vacuum and 500 two state switches to select positive
pressure. In the case of a vacuum only design, the programmable controller
would require 500 two state outputs.
An alternative control system could provide for a switching matrix that
utilizes a row and column multiplexer and a toggle valve at each surface port.
Such a multiplexed system would utilize momentary signal levels to switch
valve states, requiring only 45 outputs - 25 for the axial addresses and 20
for
the circumferential addresses.
Control method
A means for addressably controlling the state of each of the plurality of
valves is provided to selectively permit the fluid communication through a
respective one of the bores between the vacuum source and a respective one of
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the surface apertures or ports. A large number of valves and associated ports
is controlled by a valve control system such as a remote dedicated computer or
programmable logic controller (PLC), or an embedded control system or
combination thereof, with the required input/output hardware and software to
perform the switch sequencing. The valve control system discussed by example
herein is an electronic control system. Other valve control systems based on
pneumatics or mechanical linkages or hybrid combinations of control systems
may also be employed.
In the examples of web and sheet applications that follow, the X direction
is along the long axis of the web also the direction of travel, the Y
direction is
orthogonal to both the X axis and the web surface normal vector and the Z axis
is normal to the surface of the web or sheet. Since these webs or sheets are
generally flexible, the coordinate frame indicated here is relative to the
surface
of the web or sheet at any one point on its surface.
The control system software is limited to the function of 1) knowing the
state of each of the valves (C=closed, V=vacuum and P= positive pressure), 2)
knowing the x-position of the roller surface with respect to the x-position of
the
web and 3) being able to read a command file that describes the boundaries of
the cut pieces in x, y coordinates relative to the web origin.
1) Knowing the state of each valve is most easily achieved by setting all
of the valves into a known position prior to operation and then tracking the
state changes invoked by the control system within the controller software.
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2) The x-position of the roller surface with respect to the x-position of the
web is achieved by either starting both at pre-determined positions or, at a
time when the roller and web are not moving the operator can enter the current
x-position of both the web and the roller into the controller software. After
either of these initializations are completed an encoding device tracks the
roller
rotational position and the control system either tracks the web or sheet x-
position by means of an encoding devise or the controller software calculates
the web x-position based on the roller's rotational motion and estimates of
web
motion relative to the roller surface, if any.
A vision system could be utilized to scan and inspect the moving web
upstream of the vacuum roller. This vision system would detect the positions
of the cut lines and also detect flaws in the web material or in the cut
lines,
and construct the appropriate commands to allow the vacuum roller to position
and switch the valve states so as to manipulate different portions of the web
as
intended, the cut pieces removed for further handling and flawed portions of
the web discarded.
3) The control software performs a simple raster scan on the web and
produces an image of the vacuum roller valve locations superimposed on an
image of the pattern pieces. The vacuum roller valve state at each valve
location is then determined and stored for retrieval when the vacuum roller is
in motion.
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As the vacuum roller rotates during operation, the control system
determines the timing of the valve state transitions based on the x-position
of
the roller from the encoder and the stored valve states.
An example vacuum roller command file fragment required to operate the
vacuum roller valve structure shown in FIGURE 4A and 4B to pick up a
diamond shaped pattern piece out of a web is shown below.
row column - > Y axis
1 C C C C C C C C C C C C C C C C C C C C C C C C
2 C C C C C C C C C C C C C C C C C C C C C C C C
V 3 C C C C C C C C C C C V C C C C C C C C C C C C
4 C C C C C C C C C C V V V C C C C C C C C C C C
X 5 C C C C C C C C C V V V V V C C C C C C C C C C
a 6 C C C C C C C C V V V V V V V C C C C C C C C C
x 7 C C C C C C C V V V V V V V V V C C C C C C C C
i 8 C C C C C C C C V V V V V V V C C C C C C C C C
s 9 C C C C C C C C C V V V V V C C C C C C C C C C
C C C C C C C C C C V V V C C C C C C C C C C C
11 C C C C C C C C C C C V C C C C C C C C C C C C
12 C C C C C C C C C C C C C C C C C C C C C C C C
13 C C C C C C C C C C C C C C C C C C C C C C C C
14 C C C C C C C C C C C C C C C C C C C C C C C C
C C C C C C C C C C C C C C C C C C C C C C C C
Where C identifies a closed port, no fluid contact with either the vacuum
or pressure manifold.
and V identifies surface port locations that are in. fluid communication
with the vacuum manifold.
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Control method - Example with multiplexed switch array
For simplicity, the example described here is for a vacuum roller that is
able to provide only vacuum ( port valve open ) or no pressure ( port valve
closed) to any one of its surface ports.
Figure 4A shows an addressable vacuum roller 101 with an array of
surface ports 105 in fluid communication with an addressable valve (not
shown), the addressable valve can switch the port from fluid communication to
a vacuum source (not shown) or to a closed state where no air flow is allowed
to pass through the port.
As the roller 101 rotates, its rotational position is reported to the digital
control computer 441 by an absolute digital encoder 440. The control
computer compares the roller position to the position in a pre-calculated file
of
the valve states required to be switched along each row as that row passes a
specific point in the roller's rotation, usually a point where the web or a
cut
piece is either entering or exiting tangent to the roller's surface.
The control computer transmits signals 411 to a column select switch
bank 413 closing any number of normally open switches 405. At the
appropriate time, the control computer transmits signals 412 to a row select
switch bank 414 closing a single normally open switch 406.
The selected switch closures allow current to flow from the electrical
power source 426 through the switch 405 out to the roller valve (not shown) in
fluid communication with the surface port 105, the current then flows along
the conductor 415, through the valve's solenoid actuator ( not shown ), then
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along conductor 416 to the row select switch 406 then to the electrical power
source's ground 427.
The valve utilized here is of a toggle valve design - the current flowing
through the valve's solenoid switches the surface port 105 into fluid
communication with the vacuum source. When the electrical current is
released, when either switch 405 or 406 are opened, the valve remains in the
state where vacuum is ported through to the surface port 105. The port is
closed when a mechanical link closes all ports along a specific row
simultaneously (not shown ).
The multiplexed design described above allows the selective actuation of
any valve such that the roller can apply selective vacuum force to any surface
port as required.
Utilization - Vacuum Roller Arrangement To Separate
Cut Pattern Pieces From A Passing Web
Figures 3A and 3B show a conveyerized two axis cutting system as are
commonly utilized to continuously cut web material from rolls where uncut roll
goods iri web form 313 are supplied onto a flexible air permeable conveyer 321
in fluid communication with a vacuum manifold 315. The conveyer transports
the material into a cutting zone where a 2 axis cutter carriage 317 cuts
pattern
piece boundaries 328 inside of the web 312. The web is comprised of pattern
pieces 328 embedded within but severed from the surrounding scrap 329.
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The web is advanced until it is under a first vacuum roller 300 of a
traditional zoned vacuum roller design. This roller applies vacuum to it's
surface starting at the position indicated by 331, the vacuum level is
sufficient
to pull the entire web off of the conveyer and advance the web to position 332
where roller 300 closes successive axial rows of surface ports as they pass
position 332, so that the entire web can be picked up by the first addressable
vacuum roller 301. Addressable vacuum roller 301 applies vacuum starting at
position 332 to pull the entire web into intimate contact and away from roller
300.
Roller 301 then selectively switches only the surface ports that are
adjacent to the pattern pieces at position 333 from vacuum to either closed or
to positive pressure, the surface ports that are under the scrap portion of
the
web are maintained in fluid communication with the vacuum source to
maintain intimate contact with roller 301. Addressable vacuum roller 302
applies selective vacuum to surface ports that are adjacent to the pattern
pieces as they pass by position 333. As each row of addressable vacuum roller
302 passes location 334, all surface ports along that row are closed such that
pattern pieces 328 in contact with roller 302 transfer to a conveyer removal
system 340. As each row of vacuum roller 301 passes position 335 all surface
ports along that row are closed, releasing the scrap portions of the web 329
onto an appropriate scrap removal system 350.
The apparatus described above comprises an effective system to separate
cut pattern pieces from a web and deposit the pattern pieces onto an
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appropriate take-away system while also sending the scrap to an appropriate
location. A more advanced system employing a greater number of addressable
vacuum rollers would allow the separation of multiple layers of pattern pieces
and scrap. Such a system would have multiple arrangements of addressable
vacuum rollers, each such arrangement would be of the same general
configuration as described above and presented in Figure 3A and Figure 3B.
Additionally, while the web is shown moving across the roller, it is also
possible
for the web to be stationary and have the roller move across the web. Still
further, they may both move relative to each other at the same time.
Utilization - Differential Pressure To Aid An
Addressable Process On A Web
Further, the addressable vacuum roller disclosed in the present
invention may be utilized to apply selective controlled normal force to
portions
of a web where such variable pressure across and within a web is intended to
even out the tensions of a web with non-uniform elastic properties such as a
web with embroidered emblems embedded within or a web or sheet with non-
uniform structural reinforcement.
These and other objects, aspects and features of the present invention
may be realized by the provision of a vacuum roller. As will be appreciated by
one of ordinary skill in the art, an apparatus according to the invention may
be
suitable for use in any field or industry requiring selecting and removing
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pattern pieces that have been severed or cut from a web or sheet of flexible
material. Accordingly, the present invention should not be viewed as limited
to
any particular use or use in any particular industry. While the foregoing
describes what are considered to be preferred embodiments of the present
invention, it is understood that various modifications may be made thereto and
that the invention may be implemented in various forms and embodiments,
and that it may be applied in numerous applications, only some of which have
been described herein. It is intended by the following claims to claim all
such
modifications and variations which fall within the true scope of the
invention.
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