Background of the Invention
[0001] The invention disclosed herein pertains to an accumulator for accumulating a substantial
length of a running web such that if the infeed to the accumulator is stopped or slowed
for a short interval, the web in storage is paid out continuously to a web utilizing
machine so the machine has a constant supply and need not be stopped or slowed during
any part of the interval.
[0002] One common use of a web accumulator is where a web is fed from a primary supply reel
and it is necessary to splice the leading end of the web from a standby supply reel
to the trailing end of a web from the primary supply reel in a manner which will not
cause interruption of the web supply to a web consuming or utilizing device. In some
known accumulators there is a row of spaced apart rollers on one swingable arm cooperating
with another row of rollers which may be stationary or swingable on another arm. When
the one arm with a row of spaced apart rollers on it is swung away from stationary
rollers or the row of rollers on the other arm and the web is looped around the two
sets of rollers, a substantial length of web can be accumulated. During normal running
of the web, the arms will be urged to their maximum separation from each other for
accumulating and storing the maximum length of web. If the supply of web to the accumulator
is stopped for a short interval, the tension due to drawing web from the outfeed end
of the accumulator causes the sets of rollers to move toward each other while the
length of web in storage is paid out. After the end of the interval during which web
infeed to the accumulator is stopped, the two relatively movable sets of rollers separate
again to accumulate and store another length of web.
[0003] There is another general type of accumulator which has a set of rollers mounted on
a movable carriage which can run linearly toward or away from a set of corresponding
stationary rollers. The web is looped back and forth between the rollers on the movable
and stationary components so that web is accumulated as the movable carriage moves
away from the stationary assembly.
[0004] In application of web accumulators where web tension is of concern, designers must
face the problems associated with friction and inertia. The consequence of these two
factors may be appreciated when it is realized that the web may be running at a very
high rate of speed when suddenly, for some reason, such as when making a splice, the
infeeding web is stopped or decelerated. This change in web motion will result in
a reaction by the components of the accumulator. Most notable of these reactions is
the motion imparted to the movable assembly of the accumulator, whether swinging arm
or linear carriage. Minimizing the inertia and friction associated with this reaction
will minimize tension transients, and is a prime advantage of the invention described
herein.
[0005] Also notable is the change in speed of the individual rollers. While roller inertia
can actually be of benefit during a sudden deceleration, it must also be overcome
when the infeeding web is returned to the original running speed. The roller nearest
the infeed may have come to a complete stop, while each succeeding roller has slowed
to some speed slightly higher than the roller preceding it. As the web at the infeed
is accelerated it can only be drawn into the accumulator as fast as the rollers can
resume their original speeds. Since the force to accelerate these rollers is provided
only by the tension in the web, it can be seen that minimizing the number of rollers
and their inertias can allow a given system to operate successfully at lower web tensions.
In prior art machines, friction and inertia are significant factors which limit their
usefulness at low tensions. Thus, there is an important need for a web accumulator
which provides the benefits of low friction and minimized inertia, allowing it to
handle the most delicate of webs at high speeds without breakage or loss of control.
[0006] A known web accumulator is disclosed in Patent Number US-A-3540641, which embodies
all the features in the preamble of claim 1. The piston of a double acting fluid cylinder
carries a rack, which engages a sprocket on one of the axle shafts. Thus linear movement
of the piston rod causes a proportional change in the angle of the arms when the tension
in the web changes.
Summary of the Invention
[0007] The present invention provides a web accumulator comprising:
a base;
first and second axle shafts arranged with their axes in parallel and journalled
for turning relative to said base, the axes of the axle shafts being spaced from each
other along a common centreline;
first and second arms fastened to said axle shafts respectively, for swinging in
spaced apart parallel planes in response to turning of said axle shafts, said arms
extending in generally opposite directions from the respective shaft axes;
first and second wheel means fastened to said first and second axle shafts respectively;
a force producing actuator;
a flexible member formed in a closed loop around both of said wheel means and engaged
with said wheel means for turning said wheel means and the arms with said axle shafts
in response to translation of said flexible member resulting from one axle shaft being
driven rotationally, the rotation of said one axle shaft causing one arm to swing
through an angle away from one side of said centreline and the other arm to swing
away through a corresponding angle from the other side of said centreline until the
arms attain a predetermined maximum angle; and
a series of spaced apart rollers supported on each arm, the rollers on each arm
extending from the plane in which that arm swings towards the plane in which the other
arm swings to provide for a web being looped around rollers on opposite arms in succession
such that the maximum length of web accumulated in said accumulator occurs when the
arms are swung to their said maximum angle;
CHARACTERIZED BY further comprising:
a web infeed roller rotatable on the first axle shaft and a web outfeed roller
rotatable on the second axle shaft;
a torque arm fastened to one axle shaft and having a curved profile surface whose
radius from the axis of said axle shaft varies over the length of the surface; and
a flexible element connected between said actuator and said curved surface whereby
said flexible element is maintained in tangential contact with said curved surface
at points along said surface having radii of different lengths as said torque arm
is rotated owing to tension developed in said flexible element that results from actuation
of said actuator;
wherein changes in the moment of force, defined by the length of the radius at
the point of tangency times the tension in the flexible element, cause the torsional
force on the axle shaft and first and second arms to vary in correspondence with the
angle of the arms with respect to said centreline.
[0008] An important feature of the invention is that a constant force applied by the actuator
can produce a torsional force on the arms that varies with angular position. The varying
radii of the torque arm can be selected to compensate for the varying force vector
between the web and arm angles, resulting in an effectively constant web tension,
regardless of arm position.
Description of the Drawings
[0009]
FIGURE 1 is a front elevational, mostly diagrammatic, view of a web handling machine
in which the new accumulator may be installed;
FIGURE 2 is a front elevational view of the accumulator with its roller carrying arms
angulated to the position in which the maximum length of web is accumulated;
FIGURE 3 is similar to FIGURE 2 except that the arms of the accumulator would be moving
towards each other as would he the case when infeed of web is stopped and the great
length of web which is stored in the accumulator is being paid out;
FIGURE 4 is a view taken on the line 4--4 in FIGURE 5 of the mechanism for driving
the arms apart in unison to effect accumulation of a length of web;
FIGURE 5 is a side elevational view taken on the line 5--5 in FIGURE 4, of the assembled
accumulator with some parts being shown in section;
FIGURE 6 shows the two arms of the accumulator swung past each other to provide a
clear passageway for threading the web into the accumulator at the start of a web
run;
FIGURE 7 shows the position of the arms immediately after the web has been threaded
into the accumulator and separation of the arms is underway to increase the length
of the web which is to be held in storage;
FIGURE 8 is a front elevational view of an alternate but preferred embodiment of the
new accumulator;
FIGURE 9 is similar to FIGURE 8 except that the arms are swung to a position wherein
a substantially minimum amount of web would be in storage; and
FIGURE 10 is a view, partly in section, taken on a line corresponding with 10-10 in
FIGURE 9.
Description of a Preferred Embodiment
[0010] FIGURE 1 illustrates an arrangement in which the new accumulator, generally designated
by the numeral 10, can be used advantageously. In this figure, web 11 is being fed
from a supply reel 12 from which the web runs to a splicer 13. The splicer may be
any of a variety of conventional splicers which can join the leading end 14 of a web
from a standby supply reel 15 to the trailing end of the web from the primary supply
reel when the web is just about ready to run out from the primary supply reel. A pair
of translating belt devices 16 and 17 are provided for rotating the primary and standby
supply reels, respectively, for the purpose of feeding out the web to the accumulator
downstream. Typical reel driver 16 comprises a belt 18 running on rollers 19 and 20.
Roller 20 is fixed to a shaft 21 which is driven rotationally by a motor, not visible,
which is behind the front plate 22 of the machine. The belt and rollers are carried
on a frame 23 which has an arm 24 connected to the piston rod 25 of a pneumatic actuator
26. The actuator 26 is used to push the belt 18 into frictional driving relationship
with the periphery of roll of web on the supply reel. This supply reel drive device
16 is a well known type. After the web passes through accumulator 10 it goes through
a metering device 27 which is symbolically represented. From the metering device,
the web is drawn in the direction of the arrow 28 into a web utilizing device, not
shown, which could be a disposable diaper making machine.
[0011] Normally, the web 11 after leaving splicer 13, will continue over idler rollers 29
and 30 to the infeed roller 35 of the accumulator 10. And, after being looped back
and forth in the accumulator to lengthen the amount of web in storage, the web continues
from the outfeed roller 36 of accumulator 10.
[0012] When the web on primary supply reel 12 is depleted to the extent that its trailing
end is about to unwind from the reel, drive 16 decelerates reel 12 so as to bring
it to a stop, at which time the splicer 13 splices the leading end of the web on reel
15 to the expiring web. It is quite typical that conventional splicers would simultaneously
sever the expiring web, leaving what is now a continuous web running from the reel
15 through to the web accumulator. After a short interval, during which said splicing
action occurs, the run of web between splicer 13 and the infeed roller 35 is not moving,
and is under essentially the same tension as it is in regular feeding of the web.
Of course, at this time the great length of web which is formed within the several
loops in the accumulator is being paid out of the accumulator from outfeed roller
36.
[0013] Attention is now invited to FIGURE 2 wherein the parts of the accumulator are in
the position in which they would be during storage of the maximum amount of web as
is the case when the web is being drawn out of the accumulator and is being fed into
the accumulator at the same rate. In other words, in this example, the swinging arms
37 and 38 are swung apart as far as is practical in FIGURE 2 to store the maximum
amount of web 11 in the form of loops running back and forth between the arms. Arms
37 and 38 are clamped to axle shafts 39 and 40, respectively, for rotating with the
axle shafts. The axes of the axle shafts 39 and 40 lie on a center line which is marked
41 in FIGURE 2. As will be explained shortly hereinafter, axle shafts 39 and 40 are
driven apart in unison so that the arms always maintain the same angular separation
from common center line 41. The arms 37 and 38 turn clockwise together and counterclockwise
together.
[0014] Attention is now invited to FIGURES 2, 4 and 5 for a discussion of how the arms are
driven apart to bring about the accumulation of web and how the arms swing toward
each other to pay out accumulated web to the outfeed when infeed of web is stopped
for a short interval. First refer to FIGURE 4 which shows that the mechanism for operating
the arms 37 and 38 is contained within a housing whose front wall 42 appears in FIGURE
4 and whose rear wall 43 appears in FIGURE 5. In the latter figure the end walls 44
and 45 of the housing are also visible. The housing is much like a box whose rear
wall 43 is fastened to the front face plate 22 of the machine depicted in FIGURE 1.
[0015] Considering FIGURES 4 and 5, primarily, one may see that the rotatable axle shafts
39 and 40 have tooth wheels in the form of sprockets 46 and 47 fastened to them. Sprocket
46 is bolted to a clamp 48 which provides for clamping the sprocket to axle shaft
39 by way of tightening a clamping screw 49. A key and keyway, not visible, may also
engage the sprocket to the axle shaft. The other sprocket 47 is similarly bolted to
a clamping member 50 which is provided with a screw 51 which can be tightened to clamp
the sprocket to axle shaft 40. Axle shaft 40 is journaled in ball bearings 52 and
53 which are set in suitable counterbored holes in the front and rear walls 42 and
43, respectively, of the drive mechanism housing. The other axle shaft 39 is similarly
journaled for rotation in ball bearings 54 and 55. Swinging arm 37 is clamped to axle
shaft 39 by means of a clamping element 56 which is essentially a split ring that
is engaged to the shaft by tightening a machine screw 57. Swinging arm 38 is similarly
clamped to axle shaft 40 by means of a clamping member 58. The previously mentioned
outfeed roller 36 is shown in FIGURE 5 to be journaled for rotation on axle shaft
39 by means of two internal bearings 59 and 60. The roller is secured against shifting
axially by collars 61 and 62 which are clamped to axle shaft 39. Tubular roller 36
is preferably composed of a strong lightweight material so the roller has low inertia
and requires the least amount of torque to start and stop. Previously mentioned infeed
roller 35, as shown in FIGURE 5, is journaled for rotation on axle shaft 40. Roller
35 is prevented shifting axially on axle shaft 40 by means of axially spaced apart
collars 64 and 65 which are clamped to axle shaft 40. From inspection of FIGURE 5,
it will be evident that arms 37 and 38 swing in planes which are parallel to each
other.
[0016] Referring further to FIGURE 5, arm 37 has mounted to it several rollers 70, 71, 72
and 73. These rollers are freely rotatable on respective shafts 74, 75, 76 and 77.
Arm 38 has mounted to it an equal number of rollers 78-81. These rollers are mounted
for rotation on respective shafts 82, 83, 84 and 85. Roller 78 is typical. It is also
preferably composed of a lightweight rigid material for the sake of minimizing inertia.
Roller 78 is journaled for rotation on shaft 82 by means of two ball bearings 86 and
87. The outboard end of shaft 82 is provided with a c-ring 88 for retaining bearing
87 on the shaft. The other bearing 86 is pressed on the shaft and retained against
axial movement by abutting a shoulder 89 on the shaft 82. Typical roller shaft 82
is mounted to arm 38 by means of a machine screw 90.
[0017] As will be explained in detail later, arms 37 and 38 are driven rotationally, in
this illustrative embodiment, by means of two pneumatic actuators 96 and 97, whose
piston rods 98 and 104 are interconnected by two chains 115 and 118. The chains engage
the toothed wheels or sprockets 46 and 47 for rotating the axle shafts 39 and 40 and
the arms 37 and 38 thereon to accumulate web in response to movement of the pistons
100 and 101. When infeed of web to the accumulator stops, the continued draw on the
web at the outfeed causes the arms to swing toward each other. Two pneumatic actuators
96 and 97 are illustrated but it should be understood that either actuator could be
removed and replaced with a section of chain and the remaining actuator could be replaced
by a single actuator of sufficiently larger piston area to produce the actuating force
which is the sum of the forces of the two actuators.
[0018] In FIGURE 2, arms 37 and 38 are both rotated through an angle relative to imaginary
center line 41 which provides for storing the maximum length of web 11 in the loops
of web spanning between the arms. Arms 37 and 38 are swung by the greatest angular
amount as in FIGURE 2 when web 11 is being fed into infeed roll 35 and is being drawn
out of the accumulator over outfeed roll 36. In FIGURE 7, arms 37 and 38 are swung
close to each other which is a condition that occurs when infeed of web 11 is stopped
and the accumulator has paid out just about all of the web it is permitted to pay
out over the outfeed roller 36 before infeed of web must continue. The manner in which
the arms 37 and 38 are induced to swing out as in FIGURE 2 for storing the maximum
amount and are allowed to yield toward each other as in FIGURE 7 to give up the stored
amount of web will now be discussed in more detail in reference to FIGURES 4 and 5.
[0019] As previously mentioned in respect to FIGURE 4, a sprocket 47 is fastened to axle
shaft 40 for the infeed roller 36 and another sprocket 46 is fastened to the outfeed
roller axle shaft 39. Two pneumatic actuators 96 and 97 are mounted to the wall 42
of the housing. Actuator 96 has a piston rod 98 which extends slidably and sealably
through both ends of the cylinder of actuator 96. The piston fixed to rod 98 is drawn
in solid lines and is marked 100. Under ordinary operating conditions, that is, when
arms 37 and 38 are swung through the maximum angle relative to center line 41, piston
100 will be shifted by air pressure to its phantom line position designated by the
numeral 100'. Actuator 97 is similar to actuator 96. They drive and yield together
and each contributes one-half of the force for swinging arms 37 and 38. Thus, when
the piston 100 in actuator 96 is in its solid line position, piston 101 in actuator
97 is positioned as shown in hidden lines. The volume 102 on one side of piston 100
is occupied by air under pressure under all operating conditions of the accumulator.
The pressure tends to force piston 100 to the left to develop a force which is translated
to web tension. Similarly, when the volume 103 on the left side of piston 101 in actuator
97 is subjected to the same air pressure, piston 101 is biased to the right in FIGURE
4. The piston rod 104 of actuator 97 also extends through both ends of the actuator
cylinder 105. Pressurized air is supplied to the pressurizing volumes 102 and 103
of the actuators through a supply line 106. The pressurized air enters actuator 97
by way of inlet elbow 107 and pressurized air enters actuator 96 through an elbow
108. There are filter devices 109 and 110 connected to the respective cylinders 99
and 105 to allow exhaust of air when the pistons shift from their home position as
depicted in FIGURE 4. The filters also prevent air containing contaminants from being
drawn into the actuator cylinders when the pistons retract to their home positions
depicted in FIGURE 4. A flexible member in the form of a chain 115 has one of its
end 116 connected to an end of piston rod 98 of actuator 96 and has its other end
117 connected to an end of piston rod 104 of actuator 97. Chain 115 is engaged with
sprocket 46 for driving axle shaft 39. Another chain 118, has one of its ends 119
fastened to piston rod 98 of actuator 96 and the other of its ends 120 fastened to
the piston rod 104 of actuator 97. It would be possible to use toothed pulleys in
place of sprockets 46 and 47 and to use toothed timing belts in conjunction with the
pulleys instead of using chains.
[0020] It will be evident that when air pressure is applied in volumes 102 and 103 of actuators
96 and 97, respectively, pistons 100 and 101 will shift in opposite directions and
the chains running on sprockets 46 and 47 will drive axle shafts 39 and 40 and the
arms 37 and 38 thereon in unison. When pistons 100 and 101 are in the positions in
which they are depicted in FIGURE 4, arms 37 and 38 are departed by the least angular
amount from the center line which extends between the axes of axle shafts 39 and 40.
As the pistons begin to move, the arm 38 passes through a position represented by
phantom lines and marked 38'' and the other arm 37 moves through an angular position
represented by the phantom lines marked 37''. When the arms are in the position represented
by phantom lines 37'' and 38'' they are positioned approximately as depicted in FIGURE
3.
[0021] During normal operating conditions, that is, when the infeed of web to the accumulator
corresponds with the outfeed of web, the arms 37 and 38 rotate to the position in
which they are depicted in FIGURE 2 wherein they store the maximum amount of web in
the loops between the rollers 70-73 and 78-81 on the respective arms 37 and 38. In
typical applications, the web is fed into the accumulator at a speed regulated by
the position of the arms. This will cause the infeed web speed to equal outfeed web
speed when the arms are positioned for optimum web storage. This will place the arms
approximately as shown in FIGURE 2, with the air cylinder piston 100 at position 100',
as shown in FIGURE 4. Under any condition of infeed and outfeed velocities, the force
developed by the actuators 96 and 97 is translated to rotational forces in the arms
and a resultant tension in the web. If outfeed velocity exceeds infeed velocity, the
differential in web travel will tend to move the arms backwardly, compressing the
air in the cylinders. Pressure regulating devices (not shown) limit the increase in
pressure in the cylinders and therefore regulate the tension.
[0022] It should be noted that since the axle shafts 39 and 40 for the arms are driven together
the arms always will counterbalance each other. It should also be noted that the shafts
and the arms swing clockwise together as they are accumulating a length of web in
loops between them and that they rotate counterclockwise together when infeed of web
is interrupted and outfeed continues as a result of web being drawn by whatever web
consuming or utilizing device is being supplied with the web from the accumulator.
[0023] Observe in FIGURES 4 and 5 that there is another sprocket 125 fastened to axle shaft
39. A chain loop 126 runs over the sprocket for the purpose of driving another sprocket
127. Sprocket 127 is fastened to the shaft 128 of a potentiometer 129. The lead wires,
not shown, come in through a connector 132. The potentiometer is supported on a bracket
130 which is clamped to the front wall 42 of the drive mechanism housing by means
of machine bolts, such as the one marked 131, which pass through slotted holes in
the bracket to provide for shifting the potentiometer until the proper tension is
obtained in chain 126.
[0024] The potentiometer produces an analog signal relating to the angular position of the
arms. This analog signal is typically supplied to the infeed device's web speed controller,
not shown. In the application depicted in FIGURE 1 the motor being controlled is the
previously mentioned motor coupled to the shaft 21 of the belt drive mechanism 16.
If, during regular operation, draw of web at the outfeed of the accumulator 10 increases
such as to cause an angular change in the arm position of the accumulator, for example,
the controller will cause the motor which drives the belt drive 16 to run faster until
normal arm position is restored.
[0025] A feature of the invention is the ease with which the web can be threaded through
the accumulator to begin a web run without the need for zigzagging the web around
the rollers on the arms 37 and 38. Attention is invited to FIGURE 6. Here it will
be noted that arms 37 and 38 are crossed over each other as compared with their angular
positions in FIGURE 2 and 3, for example. Cross-over can be effected by grasping the
outboard end of arm 38, for example, and drawing it past arm 37. Because the arms
swing through an angle relative to the imaginary center line which runs through the
axes of shafts 39 and 40 and the rollers on each of the arms are offset from each
other as they pass the center line, the rollers on one arm can pass through the space
between rollers on the other arm . When the arms are crossed over and spaced apart
as they are in FIGURE 6, it will be evident that the web 11 can be arranged as indicated
without the need for making as much as a semi-circular loop around any of the rollers.
Cylinders 99 and 105 of actuators 96 and 97 can have the normal air pressure applied
to them at the time one arm is swung past the other manually. On the other hand, the
actuator cylinders 99 and 105 can be unpressurized before a web run starts so only
a small manual force is needed to cause them to cross over. It will now be appreciated
why, during normal operation, when the arms are not crossed over, a free space remains
between the end of actuator cylinder 99 and the displaced piston 100'. When the arm
38 is urged into cross-over position as explained in reference to FIGURE 6, piston
100' is compelled to over travel and almost abut the adjacent end of the actuator
cylinder. This amount of travel is all that is necessary to turn the axle shafts 39
and 40 enough to cause the rollers on the two arms to pass each other. Of course,
since the arms are mechanically interconnected by means of the chains when the arm,
such as 38, swings through a small angle, the other arm 37 swings through a corresponding
angle in the other direction relative to the center line and a small amount of movement
of one arm provides a rather large gap between arms for threading the web through
the accumulator when setting up for a run of the machine.
[0026] In FIGURE 7, manually deflected arm 38 has been released and tension is being applied
to the web which causes the arms to swing past each other again. The arms then slowly
swing away from each other in response to the pressure that is applied to the pistons
in the pneumatic actuators 96 and 97.
[0027] In the FIGURE 1-7 embodiment of the invention, the actual tension induced in the
web by the torsional force applied to the arms is a trigonometric function of the
angular relationship between the various web strands and the arms. As the angle between
web and arm is varied from the perpendicular, relatively constant web tension can
be achieved, for example, by having a microprocessor based controller, not shown,
vary the actuator pressure in dependence on the signal received from the potentiometer
129. An alternative embodiment of the accumulator depicted in FIGURES 8-10 overcomes
the variable torque requirement by a purely mechanical rather than electrical method.
In FIGURE 8-10 parts which are similar to parts identified in the previously discussed
embodiment are given the same reference numerals.
[0028] In this embodiment, a varying radius cam 150 is fastened to axle shaft 40 along with
sprocket 47. A closed loop chain 151 wraps around sprocket 47 and also around sprocket
46 which is on the other axle shaft 49. It will be evident that when one sprocket
is forced to turn the other will turn through the same angle and the arms 37 and 38
will swing through a corresponding angle relative to a line passing through the centers
of axle shafts 39 and 40. A short piece of chain 152 is fastened at one end 153 to
the cam and is fastened at the other of its end 154 to the end of a piston rod 155.
Piston rod 155 extends from the cylinder 156 of a pneumatic actuator 157. Cylinder
156 can swivel on a bracket 170. The cylinder has an inlet 164 for pressurized air
and a filter-muffler 165. The end 153 of the chain 152 attaches to the curved cam
150 at the place where the radius of the profile 158 of the cam is minimum. The radius
of the cam increases continually from the point 153 to the end 159 of the cam where
the radius of the cam is largest. The effective radius or moment of rotation arm is
that point at which the chain becomes tangent to the cam profile 158. From this, it
can be seen that a constant force applied by the pneumatic actuator can produce a
torsional force in the arms which varies with angular position. The varying radii
of the cam are selected to compensate for the varying force vector between the web
and arm angles, resulting in an effectively constant web tension, regardless of arm
position.
[0029] FIGURE 9 illustrates this situation where the chain 152 is tangent to the profile
158 of the cam at a point marked 162. The radius of the cam at this point is marked
160. In FIGURE 8 the radius extending from the center of shaft 40 to the point of
tangency between the chain and the profile 158 of the cam is marked 163. It will be
evident that the radius 160 in FIGURE 9 where the arms are close to each other is
substantially greater than the radius 163 in FIGURE 8 where the arms 37 and 38 are
angulated farther apart in FIGURE 8 than they are in FIGURE 9. Since the air pressure
driving the piston in actuator cylinder 156 is held substantially constant, it will
be evident that the tension force in the chain 152 multiplied by the torque radius
163 in FIGURE 8 will result in a torque related to the constant tension in chain 152
multiplied by torque arm 160.
[0030] The pressurized air is supplied to actuator cylinder 156 through a tube 164. The
cylinder is also provided with a combination muffler and filter 165 which prevents
contaminated air being drawn into the cylinder 156 when the piston moves in opposition
to the air pressure due to arms 37 and 38 being forced toward each other while web
infeed is stopped for an interval.
[0031] FIGURE 10 shows how axle shaft 40 is journaled for rotation in ball bearings 52 and
53 which are set in walls 42 and 43 of the mechanism housing as is the case in the
previously described embodiment. In FIGURE 10, however, cam 150 is fastened to shaft
40 and sprocket 47 is fastened to a member 166. Chain 152 is pivotally connected to
cam 150 with a pin 167 as is evident from inspection.
1. A web accumulator (10) comprising:
a base (42);
first and second axle shafts (39,40) arranged with their axes in parallel and journalled
for turning relative to said base (42), the axes of the axle shafts being spaced from
each other along a common centreline (41);
first and second arms (37,38) fastened to said axle shafts (39,40) respectively,
for swinging in spaced apart parallel planes in response to turning of said axle shafts,
said arms extending in generally opposite directions from the respective shaft axes;
first and second wheel means (46,47) fastened to said first and second axle shafts
(39,40) respectively;
a force producing actuator (157);
a flexible member (151) formed in a closed loop around both of said wheel means
(46,47) and engaged with said wheel means for turning said wheel means and the arms
(37,38) with said axle shafts in response to translation of said flexible member (151)
resulting from one axle shaft (40) being driven rotationally, the rotation of said
one axle shaft (40) causing one arm (38) to swing through an angle away from one side
of said centreline (41) and the other arm (37) to swing away through a corresponding
angle from the other side of said centreline (41) until the arms attain a predetermined
maximum angle; and
a series of spaced apart rollers (70-73, 78-81) supported on each arm, the rollers
on each arm extending from the plane in which that arm swings towards the plane in
which the other arm swings to provide for a web (11) being looped around rollers on
opposite arms in succession such that the maximum length of web (11) accumulated in
said accumulator (10) occurs when the arms (37,38) are swung to their said maximum
angle;
CHARACTERIZED BY further comprising:
a web infeed roller (35) rotatable on the first axle shaft (40) and a web outfeed
roller (36) rotatable on the second axle shaft (39);
a torque arm (150) fastened to one axle shaft (40) and having a curved profile
surface (158) whose radius from the axis of said axle shaft (40) varies over the length
of the surface; and
a flexible element (152) connected between said actuator (157) and said curved
surface (158) whereby said flexible element is maintained in tangential contact with
said curved surface (158) at points along said surface having radii of different lengths
as said torque arm (150) is rotated owing to tension developed in said flexible element
(152) that results from actuation of said actuator (157);
wherein changes in the moment of force, defined by the length of the radius (160,163)
at the point of tangency times the tension in the flexible element (152), cause the
torsional force on the axle shaft (40) and first and second arms (37,38) to vary in
correspondence with the angle of the arms with respect to said centreline (41).
2. A web accumulator (10) according to claim 1, wherein said flexible member (151) is
a roller chain and said wheel means (46,47) are sprockets.
3. An accumulator (10) according to claim 1 or claim 2, wherein the actuator (157) is
operated with pressurized air.
4. An accumulator (10) according to any preceding claim, wherein the ends of the rollers
(70-73,78-81), remote from the arm (37,38) on which the rollers are supported, are
free.
1. Zwischenspeicher (10) für Gewebe, mit folgenden Merkmalen:
- Ein Grundteil (42);
- erste und zweite Achswellen (39, 40), deren Achsen parellel zueinander angeordnet
und für eine Drehung relativ zu dem Grundteil (42) über Zapfen gelagert sind, wobei
die Achsen der Achswellen mit Abstand voneinander entlang einer gemeinsamen Mittellinie
(41) angeordnet sind;
- erste und zweite Arme (37, 38), die an den Achswellen (39, 40) befestigt sind, um
in mit Abstand voneinander angeordneten parallelen Ebenen in Reaktion auf eine Drehung
der Achswellen zu schwingen, wobei sich die Arme in im wesentlichen entgegengesetzten
Richtungen von den entsprechenden Wellenachsen erstrecken;
- erste und zweite Radeinrichtungen (46, 47), die an den ersten bzw. zweiten Achswellen
(39, 40) befestigt sind;
- einen eine Kraft erzeugenden Antrieb (157);
- ein flexibles Teil (151), das in einer geschlossenen Schleife um beide Radeinrichtungen
(46, 47) herum ausgebildet ist und in die Radeinrichtungen eingreift, um die Radeinrichtungen
und die Arme (37, 38) mit den Achswellen in Reaktion auf eine Translation des flexiblen
Teils (151) zu drehen, die daraus resultiert, daß eine Achswelle (40) rotationsartig
angetrieben wird, wobei die Rotation der einen Achswelle (40) bewirkt, daß ein Arm
(38) über einen Winkel von einer Seite der Mittellinie (41) weg schwingt und daß der
andere Arm (37) über einen entsprechenden Winkel von der anderen Seite der Mittellinie
(41) weg schwingt, bis die Arme einen vorgegebenen maximalen Winkel erreichen; und
- eine Serie von mit Abstand voneinander angeordneten Rollen (70 bis 73, 78 bis 81),
die an jedem Arm gehaltert sind, wobei sich die Rollen an jedem Arm von der Ebene,
in der der Arm schwingt, zu der Ebene, in der der andere Arm schwingt, erstrecken,
so daß ein Gewebe (11) nacheinander um Rollen an gegenüberliegenden Armen derart geschlungen
ist, daß die maximale Länge des in dem Zwischenspeicher (10) gespeicherten Gewebes
(11) auftritt, wenn die Arme (37, 38) in ihren maximalen Winkel geschwungen sind;
gekennzeichnet durch folgende weitere Merkmale:
- Eine Gewebeeinlaufrolle (35), die auf der ersten Achswelle (40) drehbar ist, und
eine Gewebeauslaufrolle (36), die auf der zweiten Achswelle (39) drehbar ist;
- ein Drehmomentarm (150), der an einer Achswelle (40) befestigt ist und eine gekrümmte
Profiloberfläche (158) hat, deren Radius sich von der Achse der Achswelle (40) über
die Länge der Oberfläche verändert; und
- ein flexibles Element (152), das zwischen den Antrieb (157) und die gekrümmte Oberfläche
(158) gekoppelt ist, wodurch das flexible Element in tangentialem Kontakt mit der
gekrümmten Oberfläche (158) an Punkten entlang der Oberfläche gehalten wird, die Radien
unterschiedlicher Längen haben, wenn der Drehmomentarm (150) infolge einer in dem
flexiblen Element (152) entwickelten Spannung gedreht wird, die aus einer Betätigung
des Antriebs (157) resultiert;
- wobei Veränderungen in dem Kraftmoment, das definiert wird durch die Länge des Radius
(160, 163) an dem Tangentenpunkt mal der Spannung in dem flexiblen Element (152),
bewirken, daß sich die Torsionskraft auf die Achswelle (40) und die ersten und zweiten
Arme (37, 38) entsprechend dem Winkel der Arme bezüglich der Mittellinie (41) verändert.
2. Zwischenspeicher (10) für Gewebe nach Anspruch 1, wobei das flexible Teil (151) eine
Rollenkette ist und die Radeinrichtungen (46, 47) Zahnkränze sind.
3. Zwischenspeicher (10) nach Anspruch 1 oder 2, wobei der Antrieb (157) durch Druckluft
betrieben wird.
4. Zwischenspeicher (10) nach einem der vorhergehenden Ansprüche, wobei die Enden der
Rollen (70 bis 73, 78 bis 81) frei sind, die von dem Arm (37, 38) entfernt sind, auf
dem die Rollen gehaltert sind.
1. Accumulateur de bande (10) comprenant :
une embase (42) ;
des premier et second arbres (39, 40) disposés avec leurs axes parallèles et tourillonnant
pour tourner par rapport à ladite embase (42), les axes des arbres étant espacés l'un
de l'autre le long d'un axe central commun (41) ;
des premier et second bras (37, 38) fixés auxdits arbres (39, 40) respectivement,
pour pivoter dans des plans parallèles espacés l'un de l'autre en réponse à des rotations
desdits arbres, lesdits bras s'étendant dans des directions généralement opposées
depuis les axes respectifs d'arbres ;
des première et seconde roues (46, 47) fixées auxdits premier et second arbres
(39, 40) respectivement;
un organe d'actionnement (157) produisant une force ;
un élément flexible (151) constituant une boucle fermée autour desdites deux roues
(46, 47) et en contact avec lesdites roues pour faire tourner ces dernières et les
bras (37, 38) avec lesdits arbres en réponse à une translation dudit élément flexible
(151) résultant d'un entraînement en rotation d'un arbre (40), la rotation dudit arbre
(40) faisant pivoter un bras (38) selon un angle s'écartant d'un côté dudit arbre
central (41) et l'autre bras (37) d'un angle correspondant depuis l'autre côté dudit
axe central (41) jusqu'à ce que les bras atteignent un angle maximum prédéterminé
; et
une pluralité de rouleaux espacés (70-73, 78-81) supportés par chaque bras, les
rouleaux sur chaque bras s'étendant depuis le plan dans lequel ce bras pivote vers
le plan dans lequel l'autre bras pivote pour amener une bande (11) à former une boucle
autour de rouleaux sur des bras opposés en succession de telle sorte que la longueur
maximum de bande (11) accumulée dans ledit accumulateur (10) se produit lorsque les
bras (37, 38) ont pivoté de leur dit angle maximum,
caractérisé en ce qu'il comporte en outre :
un rouleau d'alimentation de bande (35) pouvant tourner sur le premier arbre (40)
et un rouleau d'extraction de bande (36) pouvant tourner sur le second arbre (39)
;
un bras de torsion (150) fixé à un arbre (40) et possédant une surface profilée
courbe (158) dont le rayon depuis l'axe dudit arbre (40) varie sur la longueur de
la surface ; et
un élément flexible (152) monté entre ledit organe d'actionnement (157) et ladite
surface courbe (158), de telle sorte que ledit élément flexible soit maintenu en contact
tangentiel avec ladite surface courbe (158) en des points le long de ladite surface
ayant des rayons de longueurs différentes lorsque ledit bras de torsion (150) est
tourné grâce à la tension développée dans ledit élément flexible (152) qui résulte
de l'action- nement dudit élément d'actionnement (157) ;
dans lequel des variations du moment de force, défini par la longueur du rayon
(160, 163) au point de tangence multipliée par la tension dans l'élément flexible
(152), provoquent une variation de la force de torsion sur l'arbre (40) et les premier
et second bras (37, 38) en correspondance avec l'angle des bras par rapport audit
axe central (41).
2. Accumulateur de bande (10) selon la revendication 1, dans lequel ledit élément flexible
(151) est une chaîne à rouleaux et lesdites roues (46, 47) sont des pignons.
3. Accumulateur (10) selon la revendication 1 ou la revendication 2, dans lequel l'organe
d'actionnement (157) est actionné par de l'air comprimé.
4. Accumulateur (10) selon l'une quelconque des revendications précédentes, dans lequel
les extrémités des rouleaux (70-73, 78-81), éloignées de l'arbre (37, 38) supportant
les rouleaux, sont libres.