Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
r~
`'2052.01 1~91~05`
6-W
' HOLD-DOWN FINGER ARRANGEMENT; FOR USE IN PICKING AND TRANS-
'. PORTING MEANS FOR FABRIC
`` SECTIONS AND THE LIKE
The present invention relates to an appar~tus and a method
for picking and separating limp plies from a stack thereof.
The invention finds application in operations wherein
a ply of limp material, typically a piece of fabric, has to be
engaged and lifted from a stack of such plies, and then transported
in a desired manner. In the production of garments, for example,
it is conventional practice to cut simultaneously an entire stack
; of garment sections from a stacked lay-up of fabric sections. The
cut stack of fabric sections is then transferred to a subsequent
production operation, in which the sections are removed one at a
time for such operations as sewing.
In a continuing effort to automate production operations
of all kinds, substantial effort has been devoted to the develop-
ment of systems capable of lifting off and separating the uppermost
ply of fabric from a stack of pre-cut fabric sections and trans- `
porting the separated ply to a desired location for performance
of a production operation. Prior proposals for this purpose have
involved the use of means such as suction devices or pressure sensi-
``:
tive tapes, for example, for lifting off the top ply of a stack.Other arrangements heretofore proposed have involved the use of
needle-like elements for engaging and lifting off the uppermost
ply of a stack. A still further proposal for this purpose is in
U.S. Patent No. 3,756,587. ~ -
Many of the above-mentioned prior proposed arrangements
are effective at a certain level, but each has disadvantages of
: 30 one kind or another which limits its usefulness. For example, in
~4,~ .
1~917105
an operation in which all conditions are fixed, with a single size
and shape of ply and with the ply being at all times of the same
' material, it is frequently possible to adjust and adapt one or more
' of the various prior art devices for operation at a reasonable
~ level of efficiency. However, in a more typical operation, the
,,' equipment may be called upon to handle parts of a variety of sizes
' and/or shapes and also to handle parts of different materials for
'' which the prior art devices are not well suited. Even where a
' production operation involves only a single size and shape of part,
serious problems may be experienced in dealing with a plurality of
' materials on different occasions. All of the prior art systems,
i insofar as the applicant is aware, have significant shortcomings
in an environment requiring the handling of a variety of materials
and/or shapes.
The present invention now provides an apparatus for
picking and separating limp pl~es fro~ a stack'the'r'ebf, wh'ich
.:
,".5 Comprises
. (a) gripping means for engaging a first
....
limited area of the top ply and dis~
placing it away from one edge'of the
'' ply stack through a predetermined
' limited distance,
(b) ply stack hold-down means engageable
`~/ with the top of the stack in a second
' limited area spaced from said one edge a
distance less than, but greater than half
the distance of displacement, whereby to
'` engage all plies below the top ply,
,; including any plies whose'edges are
connected to said top ply,
:
` -
lO9i7~5
(c) control means for lowering said hold-down
means into engaged relation to said stack
. after actuation of said gripping means,
and
(d) means for lifting said top ply.
The present invention also provides the method of
picking and removing limp plies, one at a time, from a stack,
which comprises
; (a) engaging a first limited area of a top
,,
10ply of stack adjac~nt one edge of the
stack and displacing it in a direction
away from said one edge through a
predetermined limited distance,
(b) thereafter pressing downward on said stack .
: in a second limited area between said
; - .
:one edge and said first limited area and
` spaced from said one edge a distance less
~" than the distance of displacement but -
. greater than one-half of said distance of
displacement, wehreby to engage all plies
'`'r below the displaced top ply, including
any plies whose edges are connected to
said top ply, -~
(c) gripping said top ply, and
(d) thereafter removing said top ply.
.~ The present invention is preferably utilized in conjunc-
tion with the apparatus disclosed and claimed in Canadian Patent
Application No. 237240, filed October 8, 1975, now Canadian Patent
.
~,-3-
.
~091705
.-:
. No 1,005,088, from which the present application was divided,
which is.a picking apparatus for nipping and lifting a limp ply,
, .
which apparatus comprises a ply-gripping means including a movable
ply-gripping surface; means for moving said ply-gripping surface
into an adjustable, controlled pressure contact with a first
limited area of the top ply of a ply stack, whereby movement of
said surface will effect displacement of the top ply generally in
the plane in which the ply initially rests; a ply-retaining means
positioned immediately adjacent said movable gripping means; means
for moving said ply-retaining means into an adjustable, controlled
pressure contact with a second limited area of said top ply,
whereby upon movement of said gripping surface toward said retaining
means, said top ply is buckled into a wave between said surface and
said retaining means; said ply-gripping means and said ply-retaining
. .
. means being mounted for individually adjustable controlled pressure
.: .
contact with said first and second areas of the top ply respec-
:,~ tively; and means for nipping and lifting said wave to remove said
: top ply from the ply stack~
;. It will be understood that different ply materials may
have widely different characteristics, such as stiffness, thickness,
weight, roughness or smoothness, and susceptibility to damage or
~- marking. Moreover, with fabric plies involving patterned weaves,
a ply may have varying thickness and a stack of such plies may be
wavy and uneven as a function of the cumulative effect of the indi-
vidual ply variations~ The present invention renders possible the
: accommodation of such variable conditions and can provide reliable
and effective operations under a wide variety of conditions.
In a typical production operation, a stack of cut plies
will have been derived from a prior die cutting operation, in which
a cutting die is driven through a lay-up of fabric elements to cut
,,
:- -4-
~ ~917105
out an entire stack of shaped plies. Often such dies are not
ideally sharp, causing the edge area of adjacent plies to fuse `
together (if of synthetic material) or to become entangled (if of
natural fiber). As a result, in the picking up of a single ply,
one or more adJacent plies often are dragged along by the edges,
such that two or more plies are removed and/or the top of the stack
is disarranged. In general the ply gripping and nipping means are
` located in spaced relation to the ply edges and function to displace
one edge of the ply inwardly of the stack. If additional plies are
10 attached to the displaced edge, they are rolled over and carried
along with it for a short distance, after which they are temporarily
engaged and effectively secured by the stack hold-down element.
,, .
Upon further displacement of the uppermost ply, it is separated
along its displaced edge from the secured, underlying plies. There-
after, and prior to the next ply removal operation, the stack hold-
down element is raised well above the stack, to permit the rolled
over ply to return to its normal, flat condition on the stack.
, Preferably, a ply transport shutter means is provided forcooperative action with ply nipping and lifting means such that,
20 when a single ply has been separated off the stack and lifted at -
one edge, a plate-like transport shutter is inserted between the
stack and the partially lifted ply, to complete the ply separation
and thereafter to remove the ply from the area of the stack to
another location. It will be understood, in this respect, that even
after being nipped and separated from the stack at one edge, a ply
may still be fused or entangled with lower plies of the stack along
its other edges, such that simply attempting to lift the ply from
the stack might well cause removal or displacement of one or more
additional plies. The plate-lîke transport shutter is actuated for
,
~ ~91~5
:
movement generally in a plane parallel to the surface of the
stack, and is inserted between the stack and lifted ply, while
the lifted ply is still nipped, to progressively sever or dis-
engage the lifted ply from the remainder of the stack. The trans-
port shutter moves from the nipped edge of the ply toward its
free edge, to keep the ply in tension while effecting progressive
edge engagement. At the end of the disengagement stroke of the
shutter, the freed ply rests on the upper surface of the shutter
;, .
~ and can be transported away when the shutter is retracted. To
,.,
advantage, while one ply is being transported by the shutter,
another can be nipped and lifted, enabling optimum overall
'::
efficiencies to be realized.
Preferably, a method and means is provided for reorienting
a fabric ply, as necessary, after separation and transfer, to
assure proper alignment of the ply with the sewing machine or
, ,:,.,
other production apparatus. In this respect, it will be appre-
ciated that the initial stack of plies may be somewhat irregular
from its preliminary handling. Thus, the uppermost plies of the
.; .
stack, as they are presented to the nipping elements, may be less
than perfectly positioned in the first instance and may in any
,
event be subject to a certain amount of displacement and dis-
orientation in the course of nipping, lifting and transporting.
In practice, ideal conditions are almost never experienced, and
the separated play is thus often in need of final positioning
and orientation before processing. Advantageously, final posi-
tioning and orientation are achieved by means of a pair of sweep
arms, which engage an edge of ply and are actuated through a
lateral sweep movement along the ply edge, while the ply is
lightly urged in the direction of such edge. This combined
action quickly positions and rotationally orients the ply with
respect to the reference axes of the system.
-6-
~ lO9i70S
For a better understanding of the invention, reference
should be made to the following detailed description of a preferred
embodiment and to the accompanying drawings, in which
Figure 1 is a top plan view of a ply separating and
transporting system incorporating the invention, as utilized, for
example, in the handling of fabric sections in the manufacture of
wearing apparel.
. Figure 2 is a side elevational view of the system o
, . . .
Fig. 1.
Figs. 3 and 4 are enlarged, fragmentary view of a ply
nipping and lifting mechanism incorporated in the system of Fig. l,
.
illustrating a sequence of positions of such mechanism.
Figs. 5 and 6 are enlarged, fragmentary front and side
views of a ply gripping wheel utilized in the mechanism of Figs. 3
and 4. ~ -
Fig. 7 is an enlarged, fragmentary view of ply gripping
`~' and nipping elements incorporated in the apparatus.- Figs. 8 and 9 are enlarged, fragmentary top and bottom
views of a ply gripping wheel utilized in the apparatus together
20 with means for rotating the wheel.
Fig. 10 is a fragmentary view of a restraining shoe means
used in the apparatus for both restraining and subsequently nipping
a ply of material.
Figs. 11-14 are sequential views illustrating the manner
of operation of the ply nipping and lifting means as incorporated
in the apparatus of the invention, in conjunction with stack hold-
down means.
Figs. 1~-19 are sequential views illustrating the manner
of operation of the transport shutter means in effecting completion
30 of ply separation and transporting.
' ~ .
.. .
iO9i7~
Figs. 20-22 are sequential views illustrating the manner
of operation of the ply positioning and reorientation means.
` Referring now to the drawings, and initially to Figs. 1
. . .
and 2 thereof, there is shown a ply lifting and transporting
means as typically used in the performance of a subassembly
operation in the manufacture of wearing apparel. A stack 34 of
individual fabric sections (shirt pocket sections in the illus-
tration) is supported along side a conveyor belt 36 leading to
a sewing machine or other processing apparatus (not shown). The
mechanism of the invention serves to nip, separate and lift plies
of fabric, one at a time, from the stack 34, and to transport
them to the conveyor belt 36. After proper positioning and re-
orienting of the fabric section, it is deposited on the belt 36
for conveyance to the processing apparatus.
Typically, the stack 34 of fabric plies may be several
inches thick, comprising a large number of individual plies of
material. The stack is received within a suitable stack guide
. .
and is supported by a movable platform. The stack guide and
platform are purely conventional elements, forming no part of the
present invention, and are therefore not illustrated. It will be
understood however, that the stack guide includes a plurality of
vertically disposed guide elements for loosely guiding and con-
taining the side and end edges of the stack 34. The platform,
upon which the entire stack is supported, moves vertically within
such guides and is controlled by suitable means of conventional
and well known construction to maintain the top ply of the stack
approximately at a desired, predetermined level. Thus, as plies
; are successively removed from the top of the stack, the reduced
stack height may be sensed and the stack-supporting platform
incrementally raised to raise the top of the stack to the desired
height.
--8--
10917()S
In its illustrated form, the apparatus includes a pair of
:frame members 41, 42 which support the working parts of the appa-
ratus in desired relation to the ply stack and to the conveyor
36. A shaft 37 extends between the frame members and forms a
pivot support for a lifting arm assembly, generally designated
by the numeral 31, which comprises a pair of arm pla$es 90, 91,
journaled on the shaft 37 and connected together in spaced rela-
tion. At its outer end, the lifting arm 31 supports a ply picking ~ -
unit, generally designated by the numeral 92, to be described in
further detail.
, As reflected in Figs. 1 and 2, the lifting arm assembly 31
includes an upwardly extending lever arm 93. This arm is con-
nected by a pin 94 to the piston rod 44 of a pneumatic actuator
: 43, sometimes referred to as the lifting actuator. The body of
the lifting actuator is in turn connected to an upward extension
95 of a central frame plate 96, mounted in fixed relation to the
outer frame plates 41, 42. To advantage, the actuator rod 44
is not directly connected to the pin 94, but is slidably asso-
ciated therewith, with the pin 94 being urged against the head
88 of the actuator rod by means of a light, compression spring
85. The initial compression in the spring 85 is determined by
means of threaded collars 87 adjustable positioned on the actua-
tor rod. The arrangement is such that, when the actuator 43
is operated through a full stroke in the extending direction,
the maximum torque imparted to the lifting arm assembly thereby
'~will be accurately limited by the adjusted setting of the spring
85. The latter merely compresses when the arm assembly meets a
predetermined resistance, permitting the rod 44 to slide through
the connecting pin 94 (see Fig. 4). Desirably, the spring 85
has a relatively small spring constant, such that some degree of
-8a-
,' , .
10917~S
, .
.~:'';
variability in the overtravel of the actuator rod may be accommo-
dated without significantly affecting the compression force applied
by the spring 85.
, In the illustrated arran~ment, the lifting arm assembly
;~ 31 is also acted upon by a torsion spring 86, which is adjusted as
necessary to substantially offset any weight unbalance in the
` overall arm assembly. If desired this could also be accomplished
;
by means of a suitably positioned counterweight, In either case,
: the objective is to closely balance the assembly, so that the
.; lO operating pressures Pxerted by the arm may be very delicately and
precisely controlled by the compression spring 85.
Mounted on the end of the lifting arm assembly 31 is a
picking unit 92 which, when the lifting arm is lowered by extension
; of the actuator 43, is arranged to be brought into engagement with
the uppermost ply 46 of the ply stack 34, for engagement with the
- upper ply in a manner to be described. The picking unit includes
a pair of bearing plates 97 secured to the outer ends of the
lifting arms 90, 91 and rotatably supporting a wheel shaft 98.
Keyed or otherwise secured to the wheel shaft 98 is a ply gripping
wheel assembly 32 and a drive pinion 56a therefor. The pinion 56a
cooperates with a rack element 56, which is guided for longitudinal
movement in meshing relation with the pinion 56a by means of a
back-up roller 80 carried by the li~ting arms.
At its inner end, the rack element 56 is guided by a
bearing block 99 and is connected by a coupler 100 to the operating
rod lOl of an air actuator 55. The actuating rod 101 is normally
urged to an initial static position intermediate its fully extended
or fully retracted positions, by means of compression springs 83,
:.
'~
; -8b-
l~s~l7~ns
.
84 received over the actuating rod 101 and rack 56 respectively.
The spring 83 acts between the end of the actuator and the coupler
100, while the spring 84 acts between the coupler 100 and the
'!'' bearing block 99. The initial compression of the springs 83, 84 is
: such that the opposed compression forces are balanced when the
; actuator rod 101 is in an intermediate position, typically somewhat
toward the extended position from the midpoint of its full stroke.
~.,j
When the actuator 55, which may be referred to as the
nipping actuator, is operated to retract the rod 101, the pinion
56a and associated wheel assembly 32 are rotated in a counter-
clockwise direction, as viewed in the drawings. Suitable means,
not specifically shown, may be provided for adjustably limiting
the retracting stroke of the actuator, although in general it is
. .
sufficient to provide for a fixed stroke sufficient to achieve a
counterclockwise wheel rotation of for example 95-100 degress.
; As will be explained more fully hereinafter, the return of extending
stroke of the nipping actuator 55 is arranged to be somewhat
greater than the retracting stroke, after which the actuating rod
101 is permitted to return to it sneutral or static position. To
this end, the nipping actuator 55 is controlled by a 4-way valve
(not shown), with a one-shot pulse means being associated with the
extending stroke. Thus, after retraction of the rod to rotate the
ply gripping wheel 32 counterclockwise for 95-100 degress, the
4-way valve is reversed and a pulse of air introduced into the
opposite end of the actuator 55, extending the rod 101 sufficiently
to rotate the wheel clockwise through an angle greater than the
;~ counterclockwise rotation. After the pulse has been dissipated,
both end& of the cylinder are exhausted and the actuating rod
returns to its neutral position as determined by the respective
springs 83, 84.
.,
_ g _
- ', ~ ' :
1~)91705
; As reflected particularly in Figs, 5-9, the ply gripping
; wheel 32 advantageously comprises an assembly of toothed discs 48
- provided with a series of radially extending, relatively sharp
` teeth 54. Between the toothed discs 48 are spacer discs 49 of a
somewhat smaller diameter, which pro~ide lateral separation between
the teeth 54 and also serve to limit the effective depth of the
teeth. The specific configuration of the teeth 54 is not known
to be critical, although a relatively sharp, sawtooth configuration
has proven advantageous for use with respect to a wide variety of
ply materials. The principal requirements of the surface charac-
teristics of the wheel assembly 32 are that it be able to establish
an effective gripping relationship with a single ply 46 of material
on the stack 34, to move the ply laterally in the direction of its
principal plane, without detrimentally marking or disfiguring the
ply material. In one advantageous form of the invention, an effec-
tive wheel assembly 32, having a width of about 1/4" is provided
with teeth 54 extending about 0.015 inch beyond the outer diameter
of the spacing discs 49.
Pivotally supported by the wheel shaft 98 is a pressing
; 20 unit generally designated by the reference numeral 102. The
pressing unit includes a supporting lever 103, mounted on the wheel
shaft and provided with an outwardly extending arm 104 and an
upwardly extending arm 105. The arm 105 is normally urged into
contact with an abutment stop 106, by means of a spring 107 carried
~- by the lever arm 105 and a pin 110 carried by a pressure adjustment
lever 111. The pressure adjustment lever 111 is pivotally moun~ed
on the shaft 108 and is frictionally or otherwise retained in a
pre-set position. Counterclockwise pivoting of the adjusting
- lever 111 will result in the application of increased upward
by the spring 107, increasing the clockwise bias of the lever 103.
i,
--10--
10~17~)5
!
.. - 1--
Typically, the spring 107 is very light, affording a delicate bias
adjustment of pivoting movements of the lever 103 about the wheel
.5
shaft 98.
: Secured to the lever arm 104, typically by means of a
mounting screw 61 received in an adjusting slot 62, is a pressing
foot 33a (indicated generally in Fig. 3). In the illustrated
construction, the pressing foot 33a includes a body section 112,
to which are secured a pair of spaced ply stripping plates 113.
As reflected in Figs. 8 and 9, the stripping plates 113 are posi-
tioned in straddling relation to the ply gripping wheel 32, pre-
ferably with the plates being positioned close against the outer
discs of the wheel assembly. The lower surfaces 114 of the
stripping plates 113 constitute stripping surfaces, and the posi-
tioning and orientation of the pressing foot on the lever arm 104
is such that the stripping surface extends in overlapping relation
to the wheel assembly 32, to a point inside the radius of the
spacing discs 49. In addition, in the region of intersection of
; the stripping surfaces 114 with the peripheral outline of the
gripping wheel 32, it is desired that the stripping surfaces 114~ 20 lie at a relatively shallow angle to a tangent plane. As reflected
in Fig. 14, for example, the stripping surfaces 114 are shown to
, lie at an angle "A" of less than 45~ to the wheel tangent. The
, arrangement, as will appear, is such that a fabric ply engaged by
the toothed discs 48 and urged toward the stripping surfaces 114,
will be effectively displaced outwardly from and disengaged by the
teeth 54 of the wheel without damaging or marking the ply material.
Pivotally secured to the block 112, as by means of a pin
;; 115 (Fig. 7) is a pressing shoe 33 having a pressing surface 116
: along its bottom, which is adapted to press upon the ply stack 34,
-11 -
:. ' ' '
:" lO91t70S
.
when the lifting arm assembly 31 is lowered by extension of the
lifting actuator 43. If desired, the pressing surface may have a
rough surface for enhanced gripping action, or may even have spikes
or pins for use especially with stiff ply materials.
A small spring 57 is connected between the body portion
112 and the pressing shoe 33, urging the foot to pivot clockwise
about the pin 115 to a predetermined limit position, as reflected
in Fig. 7, for example, in such limit position, the upper surface
117 of the pressing shoe desirably lies below the stripping surfaces
114 forming, in effect, a ~aterial receiving or accumulating slot
118. The pressing shoe 33 is also provided with a nipping surface
119 at its end adjacent the wheel assembly 32. The nipping surface
119 forms an acute angle with the bottom surface 116, so as to form
a relatively sharp forward corner 120 and so as to be relatively
; evenly spaced from the outlines of the wheel assembly 32. The
adjustment and orientation of the nipping and pressing foot on the
lever arm 104 is such that, with the pressing shoe 33 in its clock-
wise limit position, there is a gap between the nipping surface 119
and the wheel teeth 54 which is slightly greater than the thickness
of one layer of the ply material,
Nipping of a single uppermost ply 46 from the stack 34,
is accomplished by first energizing the actuator 43 to extend its
operating rod 44 and pivot the lifting arm assembly 31 in a clock-
wise direction. When the picking unit 92 engages the top of the
ply stack, a reaction or resistance force is imparted to the
liftîng arm 31, resisting further clockwise movement. The operating
rod 44 nevertheless is extended through its full stroke while the
- spring 85 compresses to acco~modate continued movement of the rod
without effecting further movement of the lifting arm. The effec-
- 30
-12-
: 1~917()S
tive force applied by the compression spring 85 is adjusted in ~accordance with empirical observations, to accommodate various ~ -
materials, depending upon such factors as ply thickness, density,
resilience, etc. When the compression of the spring 85 is properly
adjusted, a full extension of the operating rod 44 will apply a
. . .
delicately controlled pressure (e.g. a few ounces) to the ply
stack 34, such that the gripping wheel assembly 32 will penetrate
a single ply sufficiently to effectively grip that ply, but will
not penetrate to the depth of a second ply.
.. .
As the lifting arm descends onto the ply stack 34, the
pressing shoe 33 engages the uppermost ply 46 somewhat in advance
of the wheel assembly 32, causing the entire pressing unit 102 to
pivot about the wheel shaft 98, against the biasing action of the
:
spring 107. Thus, in the ply nipping position of the apparatus,
as reflected in Fig. 4, the entire pressing unit 102 is displaced
in a counterclockwise direction from its rest position, such that
. the pressing shoe 33 is urged downwardly onto the ply stack with a
'~ force which is effectively independent of that applied to the wheel
assembly 32 and which is a function of the biasing force of the
.~ . .
- 20 spring 107. This biasing force may be adjusted with precision by
manipulation of the lever arm 111, so that a desired amount of
~, pressing force may be applied to the stack. Typically, enough
pressing force is applied to reliably hold the top ply against
. lateral displace~ent with respect to the shoe, without causing the
, .
. fabric to be mar~ed or otherwise disfugured. It will be understood,
of course, that the pressing unit 102, being mounted for pivoting
movement about a common axis with the gripping wheel assembly 32,
does not change its geometrical relationship to the wheel when
displaced against the resistance of the spring 107.
''
.
109 170 5
:
For a variety of reasons, the upper surface of the ply
stack 34 may be relatively uneven. In part, such unevenness is
accommodated by the spring-biased pivoting movement of the pres-
- sing unit 102, as above described. In addition, the pressing
shoe 33 itself is permitted to orient about the axis of its
pivot pin 115, to accommodate itself to the undulations of the
stack. Thus, when the pressing foot assembly 33a descends, the
shoe 33 may pivot against the biasing action of the spring 57.
If desired, the biasing force of the spring 57 may be varied by
means of an adjusting screw 121.
i A typical ply nipping and lifting sequence is reflected
schematically in the sequential views of Figs. 11-14. Initially,
the entire lifting arm assembly 31 is lowered by energizing the
- lift actuator 43, bringing the gripping wheel 32 into precisely
controlled pressure contact with the upper ply, as determined by
the spring 85, and likewise bringing the pressing shoe 33 into
precisely controlled contact with the ply, under pressure deter-
: mined by the setting of the spring 107. As reflected in the
drawing, the geometrical relationship of the ply stack 34 and
the lifting arm assembly is such that the wheel 32 and pressing
foot assembly 33a engage the ply stack adjacent but spaced in-
wardly a short distance from the edge 122 of the ply stack (which,
for purposes of description, may be considered as the forward
edge).
After the arm assembly has descended onto the stack, the
. nipping actuator 55 is energized to retract its operating rod 101
; and effect counterclockwise rotation of the gripping wheel 32. As
, will be appreciated, the teeth 54 of the gripping wheel, engaging
the uppermost ply 46,drive the ply toward the right as viewed in :~
'
-14-
. ~ '' ' ' .:
~091705
.;
,'"
-.
Fig. 11 substantially in its plane, However, since the ~1~ is held
fixed by the pressing shoe 33, only the edge portion of the ply,
to the left of the shoe, is permitted to move, As a result, the
flexible ply material, in the short area between the bottom of the
wheel 32 and the forward edge 120 of the nipping shoe, is buckled
upwardly, and carried upward and to the right by the rotation of
the wheel. After the first few degrees of rotation, the folded
over leading edge of the upwardly buckled wave of the ply comes into ~-
contact with the stripping surfaces 114~ With continued rotation
~ . -: . .
of the wheel, the ply is progressively diverted outward from and
stripped off the wheel teeth by the stripping surfaces, and a loop
or fold 65 of the ply material accumulates in the slot 118 above
,;
, the pressing shoe, It will be appreciated, in this respect, that
; the material for the accumulating loop is drawn entirely from the
;:
left side of the pressing shoe 33, with the material under the shoe
and to the right of it being held stationary by the pressure of the
shoe.
i ............................................ .
In the initial adjustment of the pressing foot assembly
on the lever arm 103, the nipping surface 119 is spaced slightly
away from the wheel teeth 54 such that, when a ply loop is driven
between the wheel and the nipping surface and on into the accumu-
lation slot 118, the two layers of fabric are resiliently gripped
between the surface 119 and the wheel assembly 32. At the same
time, the spacing adjustment and the adjustment of the spring 57 is
such that the wheel teeth 54 do not penetrate through to the lower
fabric layer, at least while the shoe 33 is pressed against the ply
stack and the wheel is in motion. If appropriate, the initial
adjusted orientation of the pressing foot assembly 33a may be such
that, when the lifting unit has descended to the Fig, 4 position,
:
:
-15-
.
:
1~9170S
the pressing shoe 33 is caused to pivot counterclockwise a few
degrees, to slightly increase the gap between the nipping surface119 and the wheel 32. When a unit is lifted, the pressing shoe
pivots back toward its initial position, to enhance the gripping
i action.
In the operation of the nipping unit, a full stroke of
the nipping actuator 55, from its intermediate, neutral position,
- is calculated to achieve about 95-100 degrees of counterclockwise
- rotation of the wheel 32, to bring the uppermost ply 46 into the
. 10 condition reflected in Fig, 11, with the loop 65 fully developed
within the accumulation slot 118, As is frequently the case, the
; forward edge 63 of the uppermost ply 46 may be fused to or other-
~: wise entangled with the forward edge 63a of one or more subsequent
plies 64. In such cases, the forward edges of the subsequent ply
.~ or plies are dragged along, when the edge of the topmost ply 46
is displaced by rotation of the gripping wheel 32. Upon completion
:: of the stroke of the nipping actuator 55, a typical condition of
. the fabric plies is as illustrated in Fig. 11,
In accordance with the invention, a hold-down element 68,
movably carried by a support 69, is actuated by completion of the
retracting stroke of the actuator 55 and caused to descend (by
, gravity or other means) upon the ply stack, to the position shown
in Fig, 12. To advangage, the hold-down element 68 includes a down- ~:wardly extending finger 71, which engages the top of the ply stack
at a point spaced inward from the forward edge 122 of the stack a
distance slightly less than the distance through which the uppermost
ply 46 is displaced during the nipping movement of the wheel 32.
Thus, when the hold-down element 68 descends, the finger 71 presses ~:
-16-
d
'
9170S
down upon and restrains the folded over edge of the next ply or
plies. Of course, if the plies separate satisfactorily in the
first instance, the hold-down finger merely descends to the top
of the stack, in the manner reflected in Fig. 14. The downward
; projection of the finger 71 is desired to avoid pressing flat and
thereby creasing a folded over ply section on the frequent
` occasions when edge entaglement does occur.
; As reflected best in Figs. 11-13, in the preferred
embodiment the operative geometrical relationships of the
10 gripping wheel 32, and its actuator, and the hold-down finger
- 71 are as follows: First, the gripping wheel 32 is located so as
to engage the top ply a short distance in from the stack. For
purposes of identification, this distance may be referred to as
.
- a first predetermined distance. Second, upon full actuation of
the nipping actuator 55, the upper ply is displaced 'hrough a
~.~ distance, referred to herein as a second predetermined distance.~.,
The second predetermined distance is less than the first, such
.` that the top ply remains underneath the gripping wheel 32 after
actuation thereof, as shown in Fig. 11. Third, the location of
the hol~down finger 71 is such that it will engage any folded
, over portion of a second ply which remains attached to the first
ply. This relationship is also illustrated in Fig. 11. Thus,
. ,~
the location of the hold-down finger is at a third predetermined
distance from the edge of the ply stack, and this third distance
is less than the second predetermined distance, in order to
clear the back edge of the first ply, but greater than half of
the second predetermined distance, in order to overlie a folded
over second ply. These various geometrical relationships,
reflected in Fig. 11, are required in order for the hold-down
finger 71 to operatively engage and hold back a folded over
second ply, as frequently results from edge entanglement or edge
fusing.
:`. . I
1091705
. . .
; When the hold-down element 68 has descended, the lifting
cylinder 43 is actuated in the reverse or retracting direction, to
.. raise the lifting arm 31 and withit the picking unit g2, The upper-
~ most ply 46 is, at this time, firmly gripped by the wheel teeth 54
against the nipping surface 119 and is thus pulled upward, as
indicated in Figs. 12 and 13, causing the nipped ply 46 to be drawn
. away from the lower plies, held by the finger 71, This action effec-
tively disengages the fused or entangled ply edges 63, 63a, at least
in the area of the picking unit 92.
.. 10 In special applications, where edge entangelement of the
individual plies is a minor problem, it might be feasible to mani-
~ pulate the picking unit 92, after raising of the arm assembly 31,
~ to transport the lifted fabric sections to a further destination,. by bodily movement of the picking unit. However, significant advan-
;~. tages, as well as higher operating efficiencies, are realized by
,
~"~ limiting the functioning of the picking unit to simply nipping and
lifting of an edge of the top ply, and providing separate transport
'. means for lifting and separating the balance of the fabric section
.. and transporting it to its furth~ destination. In this respect, ina typical stack of die cut fabric sections, edge fusing or edge
entanglement can be a problem about the entire periphery of the ~ -
- fabric section. Thus, merely separating the plies along.a forward
- 17a -
1~)91~05
.
edge section, by the procedures thus described, may not under all
; conditions be adequate to achieve effective separation of the upper-
most ply.
After the picking unit 92 has been retracted to its
raised position, as shown in Fig. 14, carrying with it the detached
forward edge of the ply 46, a transport shutter 35 is actuated from
its retracted position, shown in broken lines in Fig. 1, to an
extended position, shown in full lines in Fig. 1. The shutter 35 is
,: suitably guided and supported from the frame plates 41, 42, for
: 10 reciprocating movement in a horizontal plane, between the extended
and retracted limit positions reflected in Fig. 1. Any suitable
i1~ actuating means may be employed, such as an electric motor driving
'~ an endless chain loop (not shown), to which the shutter is connected
A single cycle of the chain loop operates to advance the shutter
from its retracted position to its advanced position and back again
r~ to its retracted position over the conveyor 36. The overall effi-
' ciency of the unit is enhanced by timing the operation of the
; picking and lifting mechanisms to synchronize with the transport
' mechanisms such that, while the shutter 35 is delivering a separated
ply to the conveyor 36, the picking and lifting unit returns to the
ply stack 34 to engage and nip the next ply.
The shutter plate 35 is provided with a tapered leading
edge, the narrowest portion of which is aligned with the picking
unit 92. Thus, when a fabric ply is engaged and lifted by the
picking unit, edge separation of a pair of plies may in some cases
be completely effective only in the immediate vicinity o~ the
picking unit itself. However, the narrow leading edge 123 of the
transport shutter is able to enter between the top and lower plies
in this narrow region. Then,as the shutter continues to advance,
-18-
`:
- 1~)9170S
and while the top ply continues to be held in the picking unit
and the hold-down element 68 continues to hold all of the remain-
. :,'
ing plies of the stack, the tapered side edges 124 of the shutter
progressively enter between the plies and effect complete separa-
tion of the forward edges 63, 63a. The shutter then continues to
advance underneath the top ply 46, gradually lifting that ply up
onto the surface of the shutter and simultaneously progressively
separating any entangled edge areas of the top and lower plies
until, finally, the entire leading edge area 123, 124 of the
shutter emerges behind the back edge 125 of the top ply. When
the shutter is thus in its fully advanced position, all of the
... . .
edges of the top ply will have been freed from the stack, and
, the entire ply will have been lifted above the stack and will be
resting upon the upper surface of the shutter. The shutter then
immediately reverses direction and returns toward its retracted
position over the conveyor 36, carrying with it the separated ply.
The gripping action of the picking unit 92 on the separate
ply, during the progressive interpositioning of the transport
shutter 35, is enhanced by the relatively sharp configuration of
the shoe tip 120. This tip resists movement of the separated
ply in the direction of shutter movement to the right, while the
edges of the ply are being freed by the shutter.
; As reflected in Fig. l, the shutter plate 35, in its fully
extended position, projects beyond the far edge 126 of the
separated ply. Mounted on the upper surface of the plate, ad-
jacent its leading edge are a pair of ply-positioning lugs 74.
These are spaced a short distance on either side of the center-
line of the shutter and include forwardly projecting lips 127
(see Fig. 16). The positioning lugs are adapted, upon the return
or transporting stroke of the shutter 35, to engage the ply edge
': :
. .
: -19-
. ' ' , ~ .
: ~09~7~)5
. .
126, to assure positive engagement of the separated ply and to
assist in its positioning.
Not infrequently, the edges of the separated ply may
exhibit a tendency to curl. Thus, to assure proper engagement
of the positioning lugs 74 with the ply edge 126, a lightweight,
displaceable hold-down element is provided to engage the upper
surface of the separated ply, as it is lifted by the advancing
., .
shutter plate and to hold the ply edge 126 flat ayainst the plate,
at least in the region of the positioning lugs 74, until the ply
,;,, .
is engaged by these lugs. To advantage, the hold-down member
may be in the form of a short length of ball chain or the like
. 81 disposed longitudinally over the centerline of the plate 35
and suspended at both ends by a bar 81a carried by a transverse
rod 82. As reflected in Figs. 16-18, as the shutter plate 35
i~.,
~ advances to its extended or pickup positions, the initially free-
i~^;.' hanging chain 81 is displaced slightly upward, as the ply 46 is
::,
picked up and supported by the advancing plate. A portion of
the chain lies between the positioning lugs 74, so that at least
in that area, the play edge is held flat on the shutter plate.
In some cases, the chain 81 may also be utilized to dissipate
static electrical charges, if any, on the separated ply.
When the transport shutter 35 initiates its return move-
ment, the separated ply typically is engaged by its back edge 126
and carried positively along with the transport shutter, until the
shutter reaches the position shown in broken lines in Fig. 1. How-
ever, immediately prior to the commencement of return movement of
the shutter, the leading edge of the fabric ply must be released
by the picking unit 92 and freed to move with the shutter.
':
:
-20-
.,
., .
:''
10917~5
i~` j
' Reliable and effective castoff of the separated ply from the
`' picking unit 92 is achieved by effecting clockwise rotation of the
;~ gripping wheel assembly 32 through an angle of rotation greater
' than the'counter~lockwise rotation which occurs during the nipping
-~ operation, This is achieved by momentarily energizing the nipping
. actuator 55 in the extending direction, by means of a pulsing valve
- (not shown'), Such momentary energizing of the actuator 55 causes
its operating rod 101 to be'extended to the right, as viewed in the .
drawings, thr:ough and beyond the "neutral" position otherwise ~:
10 determined by the static balance of the springs -83, 84, Thus, if :
the rotation of the wheel 3Z during the nipping operation is on
the order of 95-100 degrees, counterclockwise, the rotation of the
' wheel during the castoff operation typically is on the order of 10-
- 15 degrees greater, or in the'range of 105-115 degrees, for example,
This over rotation in the'castoff direction assures that the fabric
ply will be fully cleared from the picking unit at the time the
. transporting motion of the'shutter plate 35 commences, After the
:' energizing pulse to the actuator 55 has been exhausted and dissi- :
. pated, the spring 84 w~'ll return the operating rod 101 to its
:.'. 20 neutral or static position~ Thi's will impart a slight counter-
clockwise rotation to the wheel 32, but this has no effect, since
' the ply has already been reIeased by the picking unit,
It is contemplated that the movement of the transport
' shutter 35 will be carried out at relatively high speed (e.g, on
t~he order of 2~ inches per second~, To make certain that the
:-: leading edge of the separated ply is not lifted by a current of air . .
during the transport motions, hold-down guide means are provided,
, closely overlying the plane of the shutter plate 35 in the region
.
- ' '
? ~
'' , ' ~ :
} ~5)9i7~5
,,
between the picking unit 92 and the "destination" position over the
conveyor 36. In the illustrated arrangement, the hold-down means
includes a pair of longitudinally extending guide wires 128 s~r~
,.
in cantilever fashion by frame bars 129. The guide wires 128
~; extend in straddling relation to the picking unit 92, and to advan-
tage, are positioned slightly below the picking unit when the
latter is in its upraised position, as shown in Fig. 3, for example.
When the picking unit is raised with a nipped ply, the guide wires
overlie the leading edge of the ply, on either side of the picking
lO unit. As shown in Fig. 2, the shutter plate 35 is spaced slightly
below the guide wires 128 and supports 129 such that, during the
transporting stroke of the plate 35, the central portion of the ply
is closely confined between the guides and the plate.
At some point in the operating cycle, after the topmost
ply has been completely separated from the ply stack 34, the stack
hold-down member 68 is released and raised sufficiently high above
, . . .
the stack to free and permit the return to relatively flat condition
of any doubled-over end portion of a ply or plies. In a typical
system, the control signal for raising the stack hold-down element
- 20 68 may be derived from the transport shutter 35 reaching its lifted
position until the next operation of the picking unit 92, to engage
the new topmost ply and displace it laterally to the position shown
in Fig. 11. Conveniently, the hold-down 68 may be an appropriately
weighted element, which is drawn to its down or holding position by
gravity and is lifted at the appropriate time in the operating cycle
; by a solenoid or other actuator means. Desirably, the hold-down
:
element may also be utilized for actuating a stack height control
switch (not shown). Thus, when the hold-down element, upon release
and gravity movement to its holding position, drops beyond a pre-
determined limit point, a suitably positioned switch is actuated toincrementally raise the supporting platform for the ply stack.
-22-
,- ~osl7lns
When the transport shutter 35 has reached its destination~
position,~over the conveyor36,the transported ply is engaged and
held, during the return movement of the shutter plate for pick up
of a subsequent ply. As the shutter plate moves out from under-
neath the restrained ply, it arops onto the conveyor 36, whereupon
it is conveyed away to a subsequent processing operation, such as a
sewing step. Since the ply is progressively reIeased by the re-
turning shutter plate, it is appropriate to momentarily stop the
conveyor 36 while it receives the ply, to avoid skewing the ply by
lo reason of the conveyor motion. Alternatively, a suitable receiving
- platform (not shown) may be extended up in the spaces 130 between
the individual belt sections of the conveyor to receive the ply,
holding it above the conveyor surface. After the shutter has com-
pletely released the ply, the platform may be withdrawn through the '
' spaces 130 to deposit the ply onto the moving conveyor~
' As will be readily appreciated, in the various handlings
` of the ply stack, various displacements and disorientations can and
regularly do occur such that, when the ply is lifted by the picking
unit and received on the transport shutter 35 in the first instance, '
it may be in a somewhat skewed position. Likewise, although it is
intended that the back edge 126 of the separated ply be uniformly
engaged by the positioning lugs 74 in all instances, there may be
occasions when the'friction between the shutter and the ply will '
cause the ply to be accelerated with the shutter plate without
coming into proper contact with the positioning lugs 74 It is
; nevertheless contemplated that the'separated and transported plies
be placed upon the conveyor 36 in an accurately aligned and prDperly
- oriented condition, so that the plies can be effectively received
and utilized in the'processing station which comprises the destin-
ation of the conveyor 36. To this end, a'variety of positioning
and orienting means is provided in;:the illu~tra$ed apparatus.
91~05
,
1 ,
~ To assist in the proper initial engagement of the ply
j~` `
' edge 126 with the shutter plate positioning lugs 74, it may be
'' advantageous to utilize a plurality of light weigt drag bars 73,
which are loosely suspended over the ply stack 34 by means of a
'~ transverse rod 131. The drag bars are arranged to hand freely from
the supporting rod 131 and'have ply engaging surfaces 132~ When l -
the transport shutter plate 35 is actuated to its extended position,¦
lifting up a separated ply, the drag bars are lifted slightly and
swung toward the rear edge of the ply~ When the shutter plate 35
subsequently reverses direction, the'ply is restrained by the drag
~1' bars 73 and urged to slide over the top of the shutter plate 35
rr~
until engaged by the positioning lugs 74. At that time, the re-
straining action of the drag bars 73 is overcome, the bars are
lifted further in their retaining slots 133 and pivoted around with
the movement of the ply, as reflected in Fig. 18, for example.
When the transport shutter 35 reaches its destination
position over the conveyor 36, the leading edge 63 of the ply is
brought into engagement with a pair of widely spaced positioning
lugs 76, which are supported by the central frame plate 96 and
extend downward below the plane of the shutter plate 35 Appro~
priate recesses 133a are provided in the shutter plate for the
accommodation of these positioning lugs~ As will be appreciated,
the location of the lugs 76 is such, in relation to the location of
the shutter-mounted lugs 74 that, when the'shutter plate'is in its
destination position, the transported ply is engaged at both ends
by the lugs 74, 76.
A means is provided for both positioning and orienting
the transported ply before depositing the ply on the conveyor 36
To this end, the equipment includes a pair of retractable sweep
arms 78 mounted on a rock shaft 134 journaled in the'frame plates
41, 42. The shaft 134 is connected by a lever arm 135 to a sweep
arm actuator 77 anchored to the machine frame. When the actuator
-24-
~9i~()5
,:
. .
77 is energized to its extended condition, the shaft 134 is rotated
clockwise and the sweep arms are raised up above the transport
plate 35. When the actuator is retracted, the arms are lowered,
and downwardly offset extensions 136 of the sweep arms are posi-
tioned to overlie in parallel relation to the shutter plate 35 and
the trailing edge region of the separated ply, when the transport
shutter is in its destination position.
~ s reflected best in Fig. 20, the offset extensions 136
of the sweep arms are provided with downwardly projecting posi-
tioning lugs 137, which are somewhat thicker than the thickness of
the separated ply 46. When the sweep arm actuator 77 is retracted,
these lugs 137 are brought to bear resiliently on the upper surface
of the transport plate 35, with a surface sliding relationship,
. ~
such that the plate may subsequently be actuated to move back to
its extended or ply pick up position, with the lugs 137 remaining
in contact with the plate and sliding over its upper surface. The
; . . .
forward-facing edges 138 of the lugs 137 form positioning abutments,
;` for engagement with and alignment of the rear ply edge 126, in the
manner to be described. In this connection, the respective sweep 20 arms 78 may include provisions for slight longitudinal adjustment,
to effect precise alignment of the positioning lugs 137.
After lowering of the sweep arms 78, the transport
shutter plate 35 may commence its extending movement to the ply
pick-up position. As it does so, the ply edge 126 will tend to
engage at least one of the vertical abutment surfaces 138. However,
particularly with the desired rapid movement of the transport
shutter, the mere movement of the shutter cannot be relied upon to
effect proper rotational orientation of the ply in all cases, even
though the ply ~ill be driven up against one of the positioning
lugs 137. Thus, if the transported ply 46 is slightly rotationally
'' ; '
-25-
.. :
l~i7C~S
disoriented, as reflected in broken lines in Fig. 22, as the shutter
35 moves to the right, the ply edge 126 will be urged into engage-
ment with one of the positioning lugs, but the frictional forces
of the shutter plate moving out from under the disoriented ply are
not reliably effective to urge the disoriented ply into contact
with the second positioning lug. Accordingly, provisions are made
for effecting a laterally outward sweeping movement of the sweep
arms 78 during the extending movement of the shutter 35. The
combination of such movements has been found to be highly effective
....
- 10 in bringing about the desired reorientation of the ply, so`that it
is properly aligned with the conveyor 36 as it is deposited thereon.
The desired sweeping action of the sweep arm 78 is
achieved in the illustrated apparatus by providing a cam plate 139
on the upper surface of the shutter 35. The cam plate is provided
~'~^ with opposed divergently related cam surfaces 79 in its leading
section, arranged for engagement with the inwardly facing side edges
. of the sweep arm positioning lugs 137.
~` When the shutter plate 35 is in its destination position,
and the sweep arms 78 are initially lowered, the divergent cam
surfaces 79 will lie slightly inside of the positioning lugs 137,
as reflected in Fig. 21, for example. Then as the shutter moves to
the right, as indicated in Fig. 22, the lugs are engaged by the cam
surfaces 79, and the sweep arms are displaced laterally outward.
This outward movement is accommodated by pivotal mounting of the
sweep arms on support blocks 140, by means of pivot pins 141.
Spring means 142 (Fig. 1) urge the sweep arms 78 in the return
direction, when released by the cam surfaces 79.
After the shutter plate has moved completely out from
under the transported ply, the ply drops away from the sweep arms
78. Thereafter, the sweep arm actuator 77 may be extended to raise
the arms above the plate to permit a subsequent ply to be trans-
ported to the destination position.
-26-
.,
-
.
lf~917'0S
j
The picking unit, as illustrated, has some important
features, among which are the provisions fox independent movement
of the pre~sing foot assembly with respect ot the gripping wheel,
' while maintainingthe operative geometrical relationships between
these elements, so that the picking unit will accommodate itself
to uneven contours of a ply stack First, the entire picking unit
is arranged to be lowered onto the ply stack with a delicate,
. . .
easily adjustable and accurately controlled pressure, determined
by the precompression setting of the spring 85. In conjunction
with this, the pressing foot assembly itself is independently
yieldably mounted in the picking unit assembly.
The picking unit is advantageously positioned to grip the
top ply of a ply stack adjacent but spaced from the forward edge
. .~ .
of the ply. The picking unit functions initially to displace the
forward edge of the ply toward the back edge, while an intermediate
, portion of the ply is restrained by the pressing foot. This forms :
a wave in the ply, which is guided into an accumulation slot,
forming an upwardly displaced buckle or fold in the fabric, which
~: is easily nipped for withdrawal of the forward edge area of the ply.
Since most typical commercial installations of equipment of this
type will require the handling of ply stacks in which at least some
of the plies will be fused or entangled at the edges, a stack hold-
down element is provided, to engage the top of the ply stack in a
limited area, spaced inward from the forward edge of the plies a
distance slightly less than the extent of lateraldisplacement of the
topmost ply effected by operation of the picking unit. Thus posi-
tioned, the hold-down unit may descend upon the ply stack, after
actuation of the picking unit but before lifting of the nipped ply,
to secure the underlying plies, including any that may have been
,' ~ .
,',
10917(~S
.
:
. looped over and dragged along with the nipped ply because of edge
entanglement. The location and functioning of the hold-.down element
, .
`: provide for significantly improved operation of the'overall system,
` in any operations in which'edge entanglement of the plies is likely
.. to be experienced, which is the'usual case,'
Although'the''picking unit is designed and'intended princi-
. pally for picking up a single:p1;y,excluding.others, there'are some
.~ circumstances under which it is desired to pick up plies two at a
time, In this respect, the picking unit can easil~ be'adjusted to
'`~' 10 pick up precisely two plies, by control of wheeI pressure,selection
of appropriate wheel tooth depth, and the like,'
'. Another particularly advantageous feature'resides in the
'`' combined use of a picking and lifting mechanism for freeing a
limited forward edge area of the top ply, after which thé'remainder
of the ply is freed from the stack by the progressive'interposition,
:. between the part;ally lifted ply and the balance of the stack, of a
flat -plate-like shutter, To best advantage, the'leading edge'of
the shutter is tapered, to gradually complete the'severing action
along:the front edge of the ply; progressive severing of the back
20 edge of the ply is automatically achieved by the progressive inter-
- posing movement of the shutte~, as will be understood~ While the
shut.ter is being interposed between the upper ply and the balance
of the stack, the'ply itseIf is being securely heId by the picking
unit while the balance of the stack is being retained by the hold-
down element. In this respect, the specifically illustrated equip-
ment, intended for t~e handling of relative;y small parts such as
:. shirt pocket patches, funct;ons effectively with'a single picking
unit and single hold-down element. For larger ply sections, it may
be advantageous to utilize two or more picking units, Typically,
there will be a hold-down element associated with and i~ alignment
with each of the picking units.
-28-
.
I~i711~S
: .
Another advantageous feature resides in the provision,
in the picking unit, of an actuating arrangement for the gripping
` wheel 32 whicn provides for a greater displacement of the wheel in
, the cast-off direction than in the pick-up direction. In this
respect, in providing for effective a~d reliable nipping of the
fabric between the gripping wheel and the pressing shoe, it is
equally important to ensure that the nipped fabric is reliably cast-
.....
off and freed from the picking unit for the transport phase. If
there is any hang up of the fabric on the picking unit, the ply will
be crumpled at the start of the return movement of the transport
shutter, and the equipment will malfunction. A simple yet highly
~,
effective overtravel motion is provided for the castoff operation,
by arranging for a neutral or static position of the actuator,
between the extremes of its stroke. On the return or cast-off
stroke, the actuator is momentarily pulsed and then exhausted, so -
that it is driven through and beyond its neutral positon to achieve
the desired overtravel movement in the castoff operation. After
full release of the ply, the mechanism returns to its neutral or
static position.
Another highly advantageous feature resides in the pro-
. vision, for cooperation with the transport shutter plate, of later-
ally moving sweep arms, which form laterally moving edge abutment
; means for a transported ply, which is being released by the trans-
port shutter. The lateral sweep motion of the edge abutments in
conjunction with longitudinal releasing motion of the shutter plate
is highly effective in achieving proper angular orientation of a
- ply at the conclusion of the transport phase.
A balanced arm actuator arrangement of the type described
above is the subject of Canadian Patent Application No. 247,543,
filed March 10, 1976 now Canadian Patent No. 1,005,089.
~ .
., 9
,................................................................ .
,' .
