U.S. patent number 3,877,334 [Application Number 05/418,548] was granted by the patent office on 1975-04-15 for method and apparatus for cutting sheet material with a fluid jet.
This patent grant is currently assigned to Gerber Garment Techology, Inc.. Invention is credited to Heinz Joseph Gerber.
United States Patent |
3,877,334 |
Gerber |
April 15, 1975 |
Method and apparatus for cutting sheet material with a fluid
jet
Abstract
A high velocity fluid cutting jet is utilized as a cutting tool
to cut pattern pieces from limp sheet material. The limp material
is spread on a support surface and is compressed into a hardened
mass by evacuating air from within the material or applying a
positive external pressure to an exposed portion of the sheet
material. By compressing and hardening the material, the cutting
jet passes through the material along a reduced dimension and the
material cannot flutter or deflect away from the jet. A sharper and
more accurate cut results.
Inventors: |
Gerber; Heinz Joseph (West
Hartford, CT) |
Assignee: |
Gerber Garment Techology, Inc.
(East Hartford, CT)
|
Family
ID: |
23658588 |
Appl.
No.: |
05/418,548 |
Filed: |
November 23, 1973 |
Current U.S.
Class: |
83/22; 83/177;
83/169; 83/451; 83/53 |
Current CPC
Class: |
B26D
7/018 (20130101); B26F 3/004 (20130101); Y10T
83/364 (20150401); Y10T 83/0591 (20150401); Y10T
83/0443 (20150401); Y10T 83/263 (20150401); Y10T
83/748 (20150401) |
Current International
Class: |
B26D
7/01 (20060101); B26F 3/00 (20060101); D06h
007/00 (); B26f 003/00 () |
Field of
Search: |
;83/22,53,169,177,747,451,925CC |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Meister; J. M.
Attorney, Agent or Firm: McCormick, Paulding & Huber
Claims
I claim:
1. Apparatus for cutting sheet material comprising:
supporting means defining a fluid permeable support surface on
which the sheet material may rest and a fluid collection chamber
below the surface and communicating with the surface for the
transfer of fluid from the surface to the chamber;
a cutting tool mounted above the support surface and including a
fluid jet nozzle directed toward the fluid permeable support
surface to impinge a high velocity fluid cutting jet upon the sheet
material;
controlled drive means for moving the cutting tool and the sheet
material relative to one another in directions parallel to the
support surface to move the fluid cutting jet from the nozzle along
a desired line of a cut on the material; and
means for compressing the sheet material on the support surface at
least in the region of the material being cut by the jet including
vacuum generating means cooperating with the fluid collection
chamber and the fluid permeable surface for drawing a vacuum or
reduced pressure in the region of the sheet material being cut.
2. Apparatus for cutting as defined in claim 1 wherein:
the supporting means comprises a porous, fluid permeable bed
defining the support surface; and
the vacuum generating means is connected to the porous bed and
communicates with the sheet material on the support surface through
the porous bed.
3. Apparatus as defined in claim 2 wherein:
the porous, fluid permeable bed comprises a bed of bristles having
free ends substantially in a common plane to thus define the
support surface.
4. Apparatus as defined in claim 2 wherein:
the porous, fluid permeable bed comprises a honeycomb structure
having cells opening at the support surface.
5. Apparatus for cutting as defined in claim 1 wherein:
the means for compressing further comprises an air-impervious
overlay spread upon the sheet material to be cut.
6. Apparatus for cutting as defined in claim 1 wherein:
the supporting means comprises a conveyor having a movable conveyor
surface defining a portion of the support surface.
7. Apparatus for cutting as in claim 1 wherein:
the supporting means comprises a pair of conveyors placed
end-to-end with an intervening gap between the conveyors; and the
fluid jet nozzle is directed toward the intervening gap.
8. Apparatus for cutting sheet material as in claim 1 wherein:
the compressing means further comprises a roller positioned
adjacent the cutting tool and on the sheet material; and
the controlled drive means also moves the roller and the sheet
material relative to one another in one coordinate direction.
9. Apparatus for cutting sheet material as in claim 1 wherein:
the compressing means further comprises a pair of parallel rollers
positioned adjacent the cutting tool on the sheet material and an
endless belt mounted on the rollers and having one belt portion
resting against the sheet material.
10. Apparatus for cutting sheet material as defined in claim 1
wherein:
the compressing means further comprises a pressure chamber
positioned adjacent the cutting tool above the support surface and
having one side confronting the sheet material on the support
surface and having at least one aperture exposing the sheet
material to pressure within the chamber.
11. Apparatus for cutting sheet material as in claim 10
wherein:
the pressure chamber and the cutting tool are structurally
connected together; and
the drive means moves the cutting tool together with the pressure
chamber relative to the sheet material.
12. Apparatus for cutting sheet material as defined in claim 1
wherein:
the means for compressing further comprises a pair of parallel
rollers positioned adjacent the cutting tool above the support
means and the sheet material resting upon the support surface, and
an endless belt formed by an air-impervious material and mounted on
the rollers whereby the one portion of the belt between the rollers
and the sheet material resting upon the support surface may rest in
sealing relationship upon the sheet material.
13. Apparatus for cutting sheet material as defined in claim 1
wherein:
the compressing means further comprises means for sealing the sheet
material spread upon the supporting means including a roller
supported with the cutting tool for movement by the controlled
drive means and a strip of air-impermeable material wound upon the
roller whereby the strip may be anchored to the supporting means
and the roller may move with the cutting tool while the strip of
air-impermeable material is reeled onto or off of the roller in
accordance with the controlled movement of the cutting tool
relative to the sheet material on the support surface.
14. Apparatus for cutting as defined in claim 13 wherein:
the sealing means includes a pair of rollers mounted at opposite
sides of the cutting tool for movement with the tool relative to
the sheet material on the support surface and strips of
air-impervious material wound upon the respective rollers.
15. A method of cutting pattern pieces from limp sheet material
comprising the steps of:
placing the limp sheet material on a fluid permeable support
surface in a spread condition;
applying a compressive force to the spread sheet material in a
direction generally normal to the plane of the material and the
support surface on which the material is spread by drawing a vacuum
from a chamber below the fluid permeable support surface through
the support surface;
generating a fluid cutting jet;
directing the fluid cutting jet onto the compressed sheet material
at a cutting point to cut through the material in the direction
normal to the material and the support surface;
collecting the spent fluid from the jet in the chamber below the
permeable support surface; and
controllably moving the spread sheet material and the fluid cutting
jet relative one another in directions generally parallel to the
plane of the sheet material to move the cutting point of the jet
along a desired line of cut defined by the periphery of a pattern
piece.
16. The method of claim 15 wherein:
the step of applying further comprises generating a region of
increased air pressure over the limp sheet material in the spread
condition.
17. The method of claim 15 wherein:
the step of applying comprises applying an additional compressive
force to the exposed surface of the sheet material in a localized
region of the spread material adjacent the cutting point of the
fluid jet; and
an additional step comprises controllably moving the additional
compressive force and the sheet material relative to one another
during the step of directing to maintain the cutting point of the
fluid jet and the localized region subjected to the compressive
force in adjacent relationship.
18. A method of cutting sheet material as defined in claim 17
wherein:
the step of applying an additional compressive force comprises
generating a positive holddown pressure over the spread sheet
material adjacent the fluid cutting jet.
19. A method of cutting as in claim 18 wherein:
the step of generating a positive holddown pressure comprises
generating a region of increased air pressure over the spread sheet
material.
20. A method of cutting as in claim 18 wherein:
the step of generating a positive holddown pressure comprises
placing a roller on the spread sheet material adjacent the cutting
jet.
21. A method of cutting as in claim 18 wherein:
the step of generating a positive holddown pressure comprises
placing a pair of parallel rollers and an endless belt extending
around the rollers on top of the spread sheet material.
Description
BACKGROUND OF THE INVENTION
The present invention relates to the field of cutting and, more
particularly, is concerned with the cutting of sheet materials such
as limp fabrics, plastics, paper, leather, rubber and the like by
means of a high velocity fluid cutting jet.
The use of high velocity fluid jets for cutting limp materials
including clothing and upholstery fabrics has been contemplated in
the past; however, the cutting jet has never actually attained
complete acceptance or reached full development in the commercial
field of cutting limp sheet material.
The fluid cutting jet has several advantages when compared, for
example, to a mechanical cutting blade in that the jet never needs
sharpening, it does not have to change elevation during a cutting
operation and it is an omni-directional tool, that is, it has no
specific orientation and hence a complete control axis is
eliminated in an automatically controlled machine using the jet.
Also, although a laser beam is similar to a cutting jet in these
respects, the cutting jet offers the further advantage that it can
penetrate through materials to much greater depths than the laser
and without burning the materials.
Nozzles for the fluid cutting jets operate in a pressure range
between 10,000 psi and 100,000 psi. The velocity of the fluids at
these pressures varies between 1,000 feet per second and 3,000 feet
per second but the quantity of fluid involved is minimal since the
throat diameters of the nozzles from which the jets issue are in
the order of 0.004 inches to 0.010 inches.
With such high velocities, the fluid jet may displace the material
being cut or cause the material to flutter unless it is held
rigidly. The cutting of limp sheet materials such as fabrics,
plastics, paper and the like is especially prone to such a problem
due to the fact that the materials are not capable of supporting
themselves and are particularly weak when subjected to out-of-plane
forces. The materials also tend to diffuse the jet by shreading and
interfering with the jet and by capturing fluid which separates
from the mainstream of the jet.
In accordance with the present invention, the problems associated
with fluid-jet cutting operations are circumvented by compressing
the materials into a hardened mass which can be more easily
shattered by the fluid jet. In addition, apparatus employed to
compress the material also aids in holding the material in place so
that a more accurate cutting of the material along a desired path
results.
SUMMARY OF THE INVENTION
The present invention relates to a method and apparatus for cutting
sheet material by means of a high velocity fluid cutting jet. A
principal feature of the present invention is the compressing of
the material being cut into a hardened mass to permit the fluid jet
to pass through the material more easily and to hold the material
in place for accurate cutting.
The cutting apparatus which carries out the method of the invention
is comprised of supporting means defining a support surface on
which the sheet material may rest while it is being cut. The
cutting tool takes the form of a fluid jet nozzle, mounted above
the support surface, and associated pumping equipment. The nozzle
is constructed and oriented to direct a high velocity fluid jet
toward the support surface so that impingement of the jet upon the
sheet material performs the cutting function. Controlled drive
means moves the tool and the sheet material relative to one another
in directions parallel to the support surface to cause the jet
emanating from the nozzle to translate along a desired line of cut
on the material.
In accordance with the present invention, the sheet material being
cut by the fluid jet is compressed at least in the region where the
jet is operating. Compressive forces are applied to the sheet
material in a direction generally normal to the plane of the
material and the support surface on which it rests.
Various devices are employed to generate the compressive forces. A
vacuum can be generated within the material by apparatus and in the
manner described in U.S. Pat. No. 3,495,492 issued to the Assignee
of the present invention. This patent also discloses rollers and a
travelling belt mounted on the rollers which rest upon the material
and contribute to the compressive forces. Pressure can also be
applied to the sheet material by the use of a powered roller as
disclosed in U.S. Pat. No. 3,693,489 or by applying increased air
pressure to an exposed surface of the sheet material as disclosed
in U.S. Pat. No. 3,750,507, each of which patents issued to the
Assignee of the present invention.
The various compressing means may also be used in combination to
achieve maximum hardness within limp sheet material especially when
the materials are spread in a multitiered layup on the support
surface.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a cutting apparatus comprising one
embodiment of the present invention.
FIG. 2 is a transverse cross sectional view of the cutting
apparatus as viewed along the sectioning line 2--2 in FIG. 1.
FIG. 3 is a cross-sectional view of the cutting apparatus similar
to that in FIG. 2 and shows an alternate construction of the
support bed on which the sheet material is spread.
FIG. 4 is a longitudinal cross-sectional view of a cutting
apparatus comprising still another embodiment of the present
invention.
FIG. 5 is a longitudinal cross-sectional view of a cutting
apparatus comprising one further embodiment of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates in a perspective view a cutting apparatus of the
present invention. The apparatus, generally designated 10, is a
numerically controlled cutting machine which is connected by means
of a control cable 12 to a numerical controller (not shown) which
generates all of the necessary cutting commands from a previously
established or simultaneously generated cutting program. The cable
12 also transmits signals from the cutting machine to the
controller to coordinate the sequencing of the program with the
operation of the cutting machine.
The cutting apparatus 10 includes a vacuum holddown table 14 of the
type disclosed in U.S. Pat. No. 3,495,492 referenced above.
Basically, such a table has a porous, fluid permeable bed 16
defining a support surface on which the sheet material is placed in
a spread condition. A vacuum or plenum chamber 18 in the lower
portion of the table communicates through the porous bed 16 with
the sheet material spread on the support surface. The vacuum
chamber 18 is connected by means of a conduit 20 to a vacuum pump
(not shown) which has a size sufficient to maintain a reduced
pressure at the surface of the bed 16 below the sheet material. It
is desirable to establish a plurality of vacuum zones throughout
the table and to operate only the zone or zones over which the
cutting tool is operating at a given time during a cutting
operation. A zoned table is disclosed in U.S. Pat. No.
3,495,492.
The sheet material to be cut is placed on the surface of the porous
bed 16 in a spread condition. To increase the productive output of
the apparatus 10, a multi-tiered layup L is formed by placing many
sheets of the material on top of one another. If the sheet material
is air-permeable, the upper ply of the layup L may be covered with
an impermeable overlay 22 such as a sheet of polyehtylene film. The
film may also be spread over the uncovered portions of the bed 16.
Such a film prevents leakage through the permeable layup and porous
bed and enables the sheet material to be compressed more firmly
into a hardened condition.
It has been fouond that by compressing limp sheet materials into a
hardened condition, they react more uniformly to a cutting tool
even though the individual characteristics of the material in the
non-compressed condition are not changed. The materials, are,
accordingly, described as being "normalized" by the compressive
forces. The compressive forces produced by the vacuum table 14 are
caused by atmospheric pressure, and at locations within the layup,
the forces operate in a direction generally perpendicular to the
plane of the material and the supporting surface of the bed 16.
The cutting tool of the present invention is comprised principally
of a fluid jet nozzle 24 from which a high velocity fluid cutting
jet emanates during a cutting operation. The nozzle 24 is connected
directly to a Y-carriage 26 at a fixed elevation above the support
bed 16. The Y-carriage is movable relative to the table 14 in the
illustrated Y-direction and is supported on an X-carriage 28 which
spans the table 14 in the Y-direction and is movable relative to
the table in the illustrated X-direction.
The X-carriage 28 rests upon a pair of parallel racks 30 supported
longitudinally along the edges of the table 14 by a series of
brackets 32. An X-drive motor 34 mounted on the carriage 28 rotates
two pinions (not shown) engaging the respective racks 30 at
opposite sides of the table to translate the X-carriage 28 and
Y-carriage 26 over the layup L in the X-direction. The motor 34
receives displacement command signals through the cable 12 from the
controller in accordance with the cutting program.
The Y-carriage 26 is suspended over the work surface of the bed 16
on a guide rail 36 and a lead screw 38 mounted on the X-carriage. A
Y-drive motor 40 rotates the lead screw 38 which is threadably
engaged with the Y-carriage 26 to cause the carriage to translate
back and forth on the X-carriage and over the work surface of the
bed 16 in the Y-direction. Like the X-drive motor 34, the Y-drive
motor 40 receives displacement commands from the controller in
accordance with the cutting program. The drive motors 34, 40 and
the carriages 26, 28 produce composite motions of the fluid jet
nozzle 24 in the X- and Y-directions to permit the jet produced by
the nozzle to translate progressively along a cutting path P
defined by the periphery of a pattern piece to be cut from the
layup L.
As best seen in FIG. 2, the jet nozzle 24 is mounted from the
Y-carriage 26 to direct the fluid jet A toward the bed 16 along an
axis generally normal to the plane of the sheet material and the
support surface on which the material rests. A fluid pressurizing
pump 50 is mounted at one end of the X-carriage 28 and is connected
with the nozzle 24 on the Y-carriage 26 by means of a flexible
hydraulic conduit 52 and a hydraulic intensifier 54.
The pump 50 has illustrated includes a small integral reservoir in
which a pressurizing fluid is stored. The intensifier 54 is a
pressure amplifier having small and large area pistons and also
includes a fluid reservoir in which the cutting fluid, usually
water, is stored. In one form of the invention, the pump produces
an output pressure in the order of 3,000 psi and the pressurizing
fluid is then energized throughout the hydraulic conduit 52 and in
the pressure intensifier 54 on the Y-carriage 26. Within the
intensifier 54 the pressurizing fluid energizes the cutting fluid
by boosting it to a nozzle pressure in the range of 10,000 psi to
100,000 psi. The cutting fluid leaving the intensifier 54 at the
elevated pressure passes through a connecting conduit 56 to the
nozzle 24 and is discharged from the throat of the nozzle as the
high velocity fluid cutting jet A. Typically, the nozzle has a
throat aperture in the range of 0.004 inch to 0.010 inch so that
the jet A is an extremely fine high velocity stream which is fully
capable of penetrating multiple layers of limp fabric material even
after the material has been compressed in a hardened condition by
the vacuum generated within the bed 16.
The cutting action of the jet A at a cutting point on the layup is
produced by having the jet effectively shatter or rip through the
material. By compressing the limp material into a hardened
condition with vacuum, the individual plies of the material cannot
flutter or be displaced by the jet and collectively they are
subjected, as a solid, to the full fracturing forces of the jet. A
sharper cut results. Furthermore, since the vacuum holddown forces
also prevent the sheet material from shifting, the contour of the
cutting path followed by the jet as the nozzle is translated over
the layup matches the programmed cutting path P more
accurately.
One further and significant advantage achieved by combining the
vacuum holddown system with the fluid cutting jet is that the
overall thickness of the layup penetrated by the fluid jet is
reduced and concomittantly the tendency to diffuse and weaken the
jet as the material makes contact with and absorbs fluid at the
outside surface of the jet. Accordingly, the cutting phenomenon
exhibited by the jet in the upper plies of the layup L is
substantially preserved for the lower plies and the same sharp and
accurate cut is achieved throughout the depth of the layup.
The cross sectional view of FIG. 2 illustrates one embodiment of
the table 14 which provides means for generating the vacuum within
the layup L and for disposing of the fluid from the cutting jet
after it cuts through the layup. The bed 16 as illustrated is
comprised of a plurality of bristled mats arranged with the free or
upwardly projecting ends of the bristles 58 in a common plane
defining the support surface of the table. The mats rest upon a
grating 60 which in turn rests upon a series of joists 62 extending
laterally across the table 14 within the vacuum chamber 18. The
joists 62 are fixed in the frame of the table 14 and, therefore,
provide a rigid support for the grating 62 and the bristled mats of
the bed 16.
A vacuum produced within the chamber 18 is also drawn within the
region of the bristles 58 and at the supporting surface of the bed
16 by virtue of the communcation between the chamber 18 and the
lateral edge 64 of the bristles. The vacuum or low pressure at the
surface evacuates air from the layup L and draws the air
horizontally through the bristles as viewed in FIG. 2. The air is
then drawn out through the lateral edge 64 of the bristles down
through the grating 60 and the joists 62 into the vacuum chamber 18
as illustrated by the arrows. The air is then taken from the vacuum
chamber through the conduit 20 connected to the vacuum pump (not
shown).
Precise zoning of the bed 16 so that only limited portions of the
layup adjacent the cutting jet are compressed may be provided by
placing partitions within the bristles and corresponding partitions
forming sub-chambers within the vacuum chamber 18. Valves
associated with the partitioned sub-chambers are, as described in
greater detail in U.S. Pat. No. 3,765,289 having the same assignee
as the present application, operated sequentially by the motion of
the X-carriage 28 and control the generation of vacuum in the
partitioned zones of the bed 16. Only that portion of the layup
being operated upon by the cutting jet is compressed at any given
instant time in the cutting operation. It has been found, however,
that precise zoning of the bristles is not essential even though
separate sub-chambers may be employed within the base of the bed.
The resistance offered by the bristles to air flowing from adjacent
zones is adequate to limit the total flow of air pulled through the
vacuum chamber 18 to the vacuum pump.
The level of the vacuum generated within the layup is preferably
greater than that previously employed with mechanical cutting tools
such as illustrated in the above referenced U.S. Pat. No.
3,495,492. With a mechanical cutting tool, too much vacuum within
the layup of sheet material can cause so much compression of the
sheet material that the material will not permit a mechanical
cutting blade to penetrate easily through the hardened material or
translate along a cutting path through the material. Undue loading
of the blade caused by too much compression causes excessive wear
in the drive carriage and motors and can break the cutting blade.
However, with a fluid cutting jet it is felt that the cutting
operation is improved by greater compression, and vacuums or
reduced pressures in the order of 20 inches of mercury are
considered desirable.
The use of the vacuum table 14 with a fluid cuttingjet nozzle is
particularly advantageous since the vacuum system also disposes of
the spent cutting fluid. In FIG. 2, the vacuum chamber 18 receives
all of the cutting fluid from the jet A because the fluid is drawn
out of the porous bristle bed with the evacuated air. The chamber
18, therefore, serves as a collection chamber for the fluid and the
vacuum pump connected with the chamber continually draws off the
collected fluid.
To add further compressive forces to the sheet material in the
layup L, a positive holddown pressure is applied externally to the
layup by an air pressure chamber 70 suspended from the Y-carriage
26 immediately adjacent and surrounding the fluid nozzle 24. The
chamber 70 is formed by an inverted pan or shell having a large
opening confronting the upper ply of the layup. The chamber is
closely spaced to the layup to prevent pressurized air within the
chamber from escaping at a high rate under the edges of the pan.
The escaping air could cause lifting of the upper ply of the layup
or the polyethylene overlay 22 utilized with the vacuum system. The
spacing between the chamber 70 and the layup may be controlled by
the mounting structure supporting the chamber from the Y-carriage
26 or by mounting both the nozzle 24 and the chamber 70 on an
auxiliary carriage at the projecting end of the Y-carriage 26 and
moving the auxiliary carriage by means of a servomotor along an
axis normal to the plane of the sheet material on the support
surface of the bed 16.
To supply a continuous flow of pressurized air to the chamber 70,
an air pump 72 is mounted adjacent to the hydraulic pump 50 on one
end of the X-carriage 28. The air pump 72 has a discharge port
connected by means of a flexible fluid conduit 74 to an inlet
aperture on the upper side of the chamber 70. The chamber,
therefore, encloses a quantity of air at a pressure slightly above
atmospheric pressure and generates a region of increased pressure
locally around the fluid jet A during the cutting operation. As the
jet A is moved along a cutting path P over the sheet material, the
chamber 70 attached to the Y-carriage 26 moves in a corresponding
manner with the jet.
It is contemplated that the air pressure chamber 70 may be used
either in conjunction with the vacuum system or by itself to
generate compressive forces normal to the plane of the sheet
material in the layup L. Quite obviously, the combination of
positive air pressure above the layup and the negative pressure or
vacuum within the layup produces a greater hardening of the sheet
material than either one of the pressures by themselves.
FIG. 3 illustrates another embodiment of the cutting machine 10
having a cutting table 14 in which the bed 16 is comprised of a
metallic honeycomb 80. The honeycomb 80 rests upon the grating 60
in the same manner as the bristled mats in FIG. 2 and defines the
support surface on which the layup L of the sheet material is
spread for the cutting operation. The cells of the honeycomb
structure are most generally hexagonal in shape and are arranged
with the axis of the cells extending perpendicular to the support
surface for the sheet material and parallel to the fluid cutting
jet A. The cells are open at both the top and bottom ends and,
therefore, define passageways between the support surface and the
vacuum chamber 18.
The vacuum system cooperates with the honeycomb bed to compress the
layup of sheet material in essentially the same manner as the
bristle bed in FIG. 2 with one exception. Contrary to the bristles,
the honeycomb 80 is only porous in the vertical direction since the
cells define fluid passageways extending only from the support
surface downwardly through the bed to the grating 60. Accordingly,
lateral and longitudinal air flow in response to vacuum generated
in the chamber 18 is not permitted and zoning, if desired, is
greatly facilitated.
Nevertheless, the direct evacuation of air through the cells of the
honeycomb 80 generates the same low pressure region on the support
surface and within the layup to cause compressive forces to be
applied normal to the sheet material. Further compressive forces
produced by the pressure chamber 70 above the layup augment the
vacuum-generated forces in the same manner as that described in
connection with FIG. 2. Since the fluid jet A may not be entirely
dissipated by the time it passes through the open honeycomb 80 and
the grating 60, the floor of the vacuum chamber 18 absorbs any
residual energy in the jet and the chamber again collects the fluid
for discharge with the evacuated air.
FIG. 4 illustrates still another embodiment of the cutting machine
employing a high velocity-fluid cutting jet. The same reference
numbers are used for previously defined elements. The fluid nozzle
24 is mounted on a Y-carriage 26 for lateral movement over the
layup L of sheet material in substantially the same manner as that
illustrated in FIGS. 1-3. The Y-carriage 26, however, is suspended
from a stationary bridge 90 which straddles the layup. As in the
embodiment of FIGS. 1-3, the hydraulic pump 50 delivers
pressurizing fluid through the flexible conduit 52 to the
intensifier 54 on the Y-carriage and the intensifier pressurizes
the cutting fluid for discharge from the nozzle 24 as the fluid
cutting jet.
Relative motion of the nozzle 24 and the sheet material in the
Y-direction is produced by the Y-carriage 26 and associated drive
motor. Relative motion of the nozzle and the material in the
X-direction is produced by a pair of conveyors 92 and 94 placed in
end-to-end relationship with an intervening gap between the
conveyors registering with the fluid jet A. The conveyor 92 is
formed by a pair of parallel rollers 96 and 98 extending under the
layup L in the Y-coordinate direction and an endless conveyor belt
100 supported by the rollers 96 and 98. The conveyor 94 is
constructed similarly by a pair of rollers 102 and 104 and a
conveyor belt 106. Auxiliary conveyors 120 and 122 may be provided
to move the layup L on and off of the conveyors 92 and 94.
It will be readily understood that the upper surfaces of the
conveyor belts define a support surface on which the sheet material
is spread. Servo drive motors (not shown) are connected to the
rollers 96, 98, 102 and 104 to drive the belts 100 and 106 which
move the sheet material back and forth in the X-direction relative
to the cutting jet A. Composite motions of Y-carriage 26 and the
conveyors 92 and 94 achieve relative movements of the nozzle and
the layup which permit contoured cutting paths defined by the
peripheries of the pattern pieces to be cut.
The gap between the two conveyors 92 and 94 is filled with a
throatway 108 which supports the sheet material as it passes from
one conveyor to the other. A slot extends in the Y-direction
through the throatway and is aligned with the fluid jet A to permit
the jet to pass into a vacuum chamber 110.
The chamber 110 envelops both of the conveyors 92 and 94 is
connected with a vacuum pump 112 to evacuate the portion of the
layup which is in the region of the fluid jet A. The conveyor belts
100 and 106 are preferably air permeable to draw air from the layup
over a substantial zone of the layup at each side of the cutting
station defined by the bridge 90 and Y-carriage supporting the
nozzle 24. The chamber 110 also collects the fluid from the jet and
the vacuum pump 112 evacuates the fluid along with the air.
A pair of travelling belt systems 130 and 132 are mounted to the
bridge 90 at opposite sides of the fluid nozzle 24 and rest upon
the layer L to generate further compressive forces for hardening of
the sheet material as it passes under the cutting jet A. The belt
system 130 is comprised of a pair of parallel rollers 134 and 136
extending over the layup in the Y-direction and an endless belt 138
mounted on the rollers and having one belt portion resting on the
sheet material. The belt system 132 is constructed in a similar
manner and includes a pair of parallel rollers 140 and 142 and an
endless belt 144 mounted on the rollers.
The rollers 134, 136, 140 and 142 may be either powerdriven rollers
or freely rotated rollers which turn as the conveyors 92 and 94
move the layup under the nozzle 24. If the rollers 134, 136, 140
and 142 are power-driven, the drive motors for the rollers are
coordinated with the servo-motors driving the conveyors 92 and 94
to prevent slippage between the layup and the endless belts 138 and
144.
The weight of the rollers 134, 136, 140 and 142 is supported
entirely by the layup L and hence applies compressive forces to the
portions of the layup lying at each side of the cutting jet under
the belts 138 and 144. Since the belt systems 130 and 132 produce
holddown forces independently of the vacuum chamber 110, they may
be used either by themselves or to augment the compressing forces
produced by the vacuum chamber. Conversely, the vacuum chamber 110
may be used alone or in combination with the belts.
It will be observed that the belt systems 130 and 132 may
complement the vacuum system is the belts 138 and 144 are
manufactured from an air-impermeable material. Such material seals
the layups in the vicinity of the jet A if the material comprising
the layup is air-permeable and, therefore, prevents leakage of air
through the layup into the vacuum chamber even after the layup has
been cut by the jet A. The belts 138 and 144 then serve as a
non-consumable, impermeable overlay and, accordingly, the
impermeable overlay 22 may be omitted.
FIG. 5 is a longitudinal cross-sectional view of still another
cutting apparatus utilizing a water jet cutting tool in combination
with a vacuum table 14. (Elements previously described in
connection with FIGS. 1-3 bear the same reference numerals in FIG.
5). The bed 16 of the table 14 is rendered porous by bristled mats
such as illustrated in FIG. 2, a metallic honeycomb such as shown
in FIG. 3 or any other suitably porous material permitting vacuum
to be generated at the support surface of the bed to compress the
layup resting thereon. The table may also be divided into a series
of laterally extending vacuum zones which are sequentially actuated
as the X-carriage 28 traverses the table in the X direction.
A non-consumable sealing device 150 at one side of the cutting jet
nozzle 24 extends between the X-carriage 28 and the adjacent end of
the vacuum table 14. The sealing device 150 is comprised of a
roller 154 mounted on the X-carriage 28 and an impermeable overlay
156 which rests upon the upper tier of the sheet material forming
the layup L. The roller 154 has its axial ends mounted in
vertically oriented slots in the X-carriage 28 so that the roller
is free to shift vertically relative to the carriage 28 and so that
the weight of the roller rests upon the layup immediately adjacent
the cutting jet A. The overlay 156 is a strip of air-impermeable
material such as the polyethylene film which forms the overlay 22
in FIG. 1. The overlay 156 is attached to the one end of the vacuum
table 14 during a cutting operation by an anchoring clamp 158 and
the opposite end is wound upon the roller 154 in substantially the
same manner as a window shade is wound on its supporting roller. A
driving torque is constantly applied to the roller 154 during a
cutting operation (either by a torque motor or a torsion spring not
shown) to keep the overlay 156 under tension and to permit the
overlay to be reeled onto or off the roller 154 in synchronism with
the motion of X-carriage 28 over the layup. Accordingly, the
overlay 156 is laid down upon or retrieved from the layup L as the
X-carriage moves longitudinally back and forth along the table 14
and the entire expanse of the layup between the cutting jet nozzle
24 and the anchoring clamp 158 remains covered and sealed during
the cutting operation. Vacuum or the reduced pressure generated at
the support surface of the porous bed 16 cooperates with the
overlay 156 to compress the layup into a hardened mass, and to
thereby aid the cutting process as described above in connection
with FIGS. 1-3.
A corresponding sealing device 160 extends between the X-carriage
28 and the end of the vacuum table 14 opposite the anchoring clamp
158 to seal that expanse of the layup at the side of the cutting
nozzle 24 opposite the sealing device 150. The device 160 has the
same construction as the device 150 and includes a rotationally
torqued roller 164 supported on the X-carriage 28 and an
air-impermeable overlay 166 wound upon the roller 164 and anchored
at the opposite end of the table.
It will be understood that the sealing devices 150 and 160 at
opposite sides of the cutting jet A, replace the overlay 22 shown
in FIGS. 1-3 and operate in substantially the same manner. Several
points are noteworthy, however. The overlays 156 and 166 are not
consumed or cut during the cutting operation. Also, sealing of the
longitudinal edges of the layup with the overlays 156 and 166 is
accomplished more efficiently by positioning blocks of sealing
material, for example, a closed-cell, foamed plastic, adjacent the
longitudinal edges of the layup and spreading the overlays 156 and
166 over the top of the layup and the sealing blocks. A more
complete description of the windowshade type sealing devices 150
and 160 may be had by reference to U.S. Pat. No. 3,742,802 issued
July 3, 1973 to the Assignee of the present invention.
While the present invention has been described in several preferred
embodiments, it will be understood that still further modifications
and substitutions can be had without departing from the spirit of
the invention. For example, in addition to the bristle bed or
honeycomb beds described above, other liquid permeable materials,
such as open-celled plastic foam, may be employed. Although such
foam may also be cut by the fluid jet A, it can be treated as an
expendible material and may be replaced from time to time after
extended use. The pressure chamber 70 may take other forms such as
illustrated in U.S. Pat. No. 3,750,507 referenced above. Free
rolling spherical weights within a cage suspended from either the
X- or Y-carriages as shown and described in U.S patent application
Ser. No. 282,544, filed Aug. 21, 1972 by the Assignee of the
present invention may be used to compress the sheet material in the
layup. A conveyor-type bed different from that illustrated in FIG.
4 may be formed by mounting segments of honeycomb on interconnected
slats so that an endless belt is formed. The endless sealing belts
138 and 144 shown in FIG. 4 may be attached to the X-carriage in
the embodiment of FIG. 1 for their sealing function. The rollers
136 and 140 can operate without the associated belts as described
in U.S. Pat. No. 3,693,489 referenced above to compress the sheet
material. It will also be understood that the fluid nozzle 24 can
be held by a rigid frame over the layup and the layup can be moved
relative to the nozzle in both the X- and Y-directions.
Accordingly, the present invention has been described in several
embodiments by way of illustration rather than limitations.
* * * * *