Note: Descriptions are shown in the official language in which they were submitted.
~1535713
SELF I~CTIJATI~IG YARN FEED AND D~IVF~ BELT
ARRANGE`l~::NT F'OR CIRCULAI~ :~NI'rrrING ,~CH:~.`IES.
Background of the Invention
_ _
The present invention relates to yarn feed de~ices
for use in conjunction with circular knitting machines and
to drive means for such yarn feed devices. More particularly,
the invention is directed to a self actuating yarn feed
device for use in conjunction with a circular knitting
machine requiring uniform or non-uniform xates of delivery of
yarn to the various feeds or in conjunction with the knitting
machine having striping boxes or similar means requiring
selective, intermittent delivery of particular yarns during
the knitting operation. The yarn feed device utilizes a
feed wheel having arl outer cylindrical surface that is
divided into an upper high friction yarn advancing portion
and a bottom, low friction yarn idling portion. Additionally, the
present invention relates to a means of driving the yarn
feed device incorporating a series of belts, each operable
at a different speed for precisely feeding the appropriate
quantity of a particular yarn to the associated yarn feed in
the knitting area of the machine.
lq~&~S's ~
Description of the Prior ~rt
Positive yarn Eeed devices are well known in the
knitting art. For example, the device disclosed in U. S.
Patent No. 3,090,215 provides a positive yarn feed by the use of
a feed wheel or roller associated with each yarn cone. A plurality
of feed wheels are arranged in a circular array adjacent the
yarn cones, and each feed wheel is powered by a rotating flat
tape contacting the circumferential surface of the feed roller.
Positive feed of the yarn is accomplished by passing the yarn
between the outer cylindrical surface of the feed wheel and the
inside surface of the flat tape. This device, however, does not
have a provision for stopping a particular yarn feed and adds
substantial difficulty to the initial set-up of the machine or
the restart of a machine after there has been a pressoff. Most
significantly, such device cannot be utilized on knitting
machines having pattern wheels or striping boxes requiring
non-uniform or intermittent yarn feed.
Improved yarn feed devices such as those disclosed
in U. S. Patent Nos. 3,802,228; 3,418,831i 3,950,966 and 4,043,155
attempted to overcome the difficulties discussed above. The
3,802,228 patent discloses a positive yarn feed device that
can be moved manually to an out-of-action position to allow the
knitting machine to be set up or to manually by-pass certain
feed devices at the appropriate intervals during the knitting
operation. The device of the 3,651,668 patent also provides
positive feed of yarn and contains provisions for directing the
yarn to a non-feed position. However, there are no provisions
for automatic operation between the feed and the non-feed
position in either device.
~15~5 ~ ~
The device disclosed in the 3,41~,831 patent uses
mechanical or electrical means to automatically operate the
positive feed feature. However, both the electrical and the
mechanical embodiments of this device are complex utilizing
yarn guide brackets movable from a first yarn idling position
to a second yarn advancing position, to direct the yarn
between the surface of the feed wheel and the flat tape at
the appropriate time.
The devices of U. S. Patent Nos. 3,950,966 and
4,043,155 utilize the combination of a weighted arm and friction
devices on the yarn itself to move the yarn from a feed to a
non-feed position. Such devices, however, require substantial
time to set up as both the amount of friction and the position
of the counterweights must be precisely adjusted on each
individual yarn feed. During operation of the knitting machine,
when yarn is drawn off the cones the tension and the surface
friction of the yarn entering the feed device may vary thereby
requiring readjustment of both the counterweights and the
friction devices for continued proper operation. Otherwise, there
may be overfeed of yarn or "hunting" of the weighted arm
resulting in failure of the positive feed device to remain fully
activated.
Although the devices of the 3,950,966 and 4,043,155
patents direct the yarn between the cylindrical surface of
the feed wheel and the tape when in the feed position, there is
a commercially available feed device incorporating a feed wheel
having high and low friction portions of its cylindrical surface.
However, such device uses a spring controlled arm to move the
yarn from the feed to the non-feed position. Such device is
;3S~
unsatisfactory for the same reasons as the devices clisclosed in
patent Nos. 3,950,966 and 4,043,155. These devices all utilize
preset and constant parameters (e.g., the force exerted by a
counterbalance or a spring; friction on the surface of yarn)
to respond to variations inherent in the knitting process such
as tension on the yarn wound on the cone or non-uniformity of
the surface of yarns.
Yarn feed drive means utilizing drive belts in
various planes corresponding to the heights of the various feed
wheels are known. However, such devices utilize either a plurality
of drive belts driven at the same respective circumferential
speeds, as in U. S. Patent No. 3,785,176, or utilize relatively
complex and expensive driving wheels having variable circumferences
against which the flat tape rotates, as in U. S. Patent No.
3,243,091.
357~3
Summary of the Invention
Broadly, it is an object of the present invention to
provide an improved apparatus for positive feed of yarn which
eliminates one or more of the aforesaid shortcomings of the
prior art. Specifically, it is within the contemplation of the
present invention to provide improved positive yarn feeding
apparatus which incorporates a plurality of feed wheels. Each
feed wheel has an outer cylindrical surface, the top portion of
which is covered with a high friction material and the
bottom portion of which is of low friction material, such as
polished steel. A fixed yarn inlet guide directs the yarn
along the top, high friction surface of the feed wheel.
When tension is placed upon the yarn as a result of demand
for yarn by the needles, the high friction surface of the
rotating feed wheel draws yarn at the appropriate speed.
The feed wheel is caused to rotate by one of two or more
drive belts each of which are located in a different horizontal
plane. Each drive belt can be rotated at a different circumferential
speed relative to the other drive belts by virtue of the
drive means assembly of the present invention.
It is a primary object of the present invention to
provide a yarn feed apparatus that is capable of responding
substantially instantaneously to both demand and non-demand of yarn.
It is a further object of the present invention to
provide a yarn feed apparatus that is self actuating yet can
be used in conjunction with knitting machines requiring
uniform, non-uniform or intermittent yarn feed in conjunction
with pattern wheels, striper boxes or the like withou~
requiring modifications to the yarn feed structure.
5~
It is a further object of the present invention to pro-
vide a yarn feed device which has few moving parts and requires
little or no adjustment for different yarns.
It is a further object of the present invention to
provide a yarn feed device that is self-actuating and need not
be manually moved from the non-feed to -the feed position or from
the feed to the non-feed position in order to set up the machine
or to restart the machine after a yarn breaks thereby resulting
in higher production from each machine.
It is a further object of the present invention to
provide a yarn feed apparatus that can be easily fit on existing
knitting machines.
It is a ~urther object of the present invention to
provide a yarn feed apparatus that can supply different selections
of yarn at different respective speeds of feed relative to the
other yarns.
It is a still further object of the present invention to
provide a means of varying the speed of either one or more yarns
utilizing readily available economical components such as a
variable speed V-belt pulley.
In accordance with an illustrative embodiment demonstrating
ob~ects and features of the present invention, there is provided
a positive yarn feed device for a knitting machine comprising
a mounting frame, a feed wheel mounted on said frame for rotation
about a vertical axis. The feed wheel has an outer cylindrical
surface that is divided into an upper segment and a lower
segment by a medial plane perpendicular to the vertical axis.
The upper segment of the cylindrical surface has a relatively
high friction surface and the lower segment has a relatively
low friction surface. Means are provided for rotating the
feed wheel. A fixed yarn guide means is mounted on the
frame in operative relationship to the feed wheel and a yarn
5~
inlet guide lS mounted in the fixed yarn guide meanC;. The yarn
inlet guide has a bottom e~it surface defining an e~i-t plane
which is above the medial plane of the roller whereb~ yarn
exiting from the yarn inlet guide in the fixed yarn ~Juide
means is delivered to the upper segment of the feed wheel.
The present invention also provides drive means for
- the plurality of positive yarn feed devices on a knittiny
machine having multiple feeds which comprises a support frame
and a first plurality of yarn feed wheels rotatably mounted on
a bracket attached to the support ~rame in a first common
horizontal plane. A second plurality of feed wheels are rotatably
mounted on a bracket attached to the support frame in a second
common horizontal plane. A first drive means is associated with
the first plurality of yarn feed wheels and a second drive means
associated with the second plurality of yarn feed wheels. Means
for propelling the first drive means and the second drive means
comprise a drive frame having a first vertical shaft rotatably
mounted in the drive frame with the first variable speed driven
pulley journaled at one end thereof and an output pulley journaled
at the other end wherein the output pulley rotates in the first,
common horizontal plane responsive to rotation of the first
variable speed driven pulley. A second vertical shaft is rotatably
mounted in the drive frame having a second variable speed driven
pulley journaled at one end thereof in a plane common to the
first variable speed driven pulley and an output pulley journaled
at the second end wherein the output pulley rotates in the second
common horizontal plane responsive to rotation of the second
variable speed driven pulley. The drive shaft and a drive pulley
journaled to the drive shaft in a plane common-to the first and
~5~5~
second variable speed driven pulleys are provide~ alony with means
for connecting the drive pulley to the first and second variable
speed driven pulley. Means are provided for rotatiny the drive
shaft.
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llSr~JS ~ C~
Brief Descri~ n of the Drawings
. . _ _ .
The above brief description, as well as further
objects, features and advantages of the present inven-tion, will
be more fully appreciated by reference to the following detailed
description of the presently preferred, illustrative embodiment
according to the present invention, when taken in conjunction
with the accompanying drawings, wherein:
FIG. 1 is a side elevational view of the improved
yarn feed drive means of the present invention, shown in con-
junction with a portion of a circular knitting machine, wherein
some components of the machine are shown schematically;
FIG. 2 is a plan view of the drive portion of the
machine, with portions of the support structure cut away for
clarity;
FIG. 3 is a side elevational view taken from the
left of FIG. 1, with portions of the circular knitting
machine broken away;
FIG. 4 is a sectional view taken substantially along
the line 4-4 of FIG. 1 in the direction of the arrows showing
the relative position of the feed wheel assemblies and a striper
box
FIG. S is an end elevational view showing the
details of a feed wheel assembly of the present invention;
FIG. 6 is a side elevational view of the feed wheel
taken from the left of FIG. 5;
FIG. 7 is a side elevational view of the feed
wheel assembly of the present invention in a larger scale
showing the position of the yarn on the feed wheel in the
~ii3570
various conditions;
FIG. 8 is a side elevational view of an alternate
embodiment of a feed wheel assembly of the present invention; and,
FIG. 9 is an end elevational view of the alternate
embodiment of FIG. 8.
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~ . . , ~
~S3~7~?
Detailed Description
Referring now to the clrawings and specifically to
FIG. 1, there is provided an improved ~arn feed device in
accordance with the present invention for use in conjunction
with a circular knitting machine. The preferred embodiment of
the present invention is shown in conjunction with a knitting
machine utilizing a striper box 12 and four alternately
fed yarns Ya, Yb, Yc and Yd at each striper box. A typical
machine may contain thirty two (32) striper boxes and one hundred
and twenty eight (128) yarns and associated yarn feed assemblies.
The present invention contains provisions whereby the speed
at which each of the yarns is fed can be varied relative to
the other yarns to compensate for variations in the yarn or
the yarn supply requirements of a particular pattern.
The yarn feed structure 10 of the present invention
includes a plurality of feed wheel assemblies 11 mounted from
fixed rings 14, 16 supported above the primary knitting elements
(not shown) of a circular knitting machine, and typically beneath
the cones of yarn (also not shown). In the conventional manner,
a striper box 12 is associated with each feed, and where the
striper box 12 utilizes four different colored yarns Ya, Yb, Yc
and Yd, each yarn is advanced by a separate feed wheel assembly
11. In order to facilitate the installation of four feed whee~
assemblies 11 each feed wheel assembly is suspended from either
fixed ring 14 or 16 by alternating short brackets 20 and long
brackets 22. Each feed wheel assembly is comprised of a feed
~15~570
wheel or roller 18, 19 rotatably mounted Erom short and long
brackets 20, 22, respectively. ~he other components compr,ising
the feed wheel assembly 11 are discussed more fully below with
reference to FIGS. 4 through 7.
A plurality of feed wheels 18 suspended from short
brackets 20 mounted on fixed ring 14 around the circumference of
fixed ring 14 define a first horizontal plane of rotation, and
the plurality of feed wheels 19 suspended from long brackets
22 mounted on the fixed ring 14 define a second horizontal plane
of rotation below the first horizontal plane of rotation.
' Similarly, the plurality of feed wheels 18 suspended from the
short brackets 20 mounted on the fixed ring 16 define a third
horizontal plane of rotation below the second horizontal plane
of rotation and the plurality of feed wheels 19 suspended from
the long brackets 22 mounted on the fixed rings 16 define a
fourth horizontal plane of rotation below the third horizontal
plane of rotation.
Each feed wheel 18, 19 is separated into an upper
yarr. engaging portion ~4 and a lower driving portion 26 by a
central flange 28. A first feed belt 30 extends around the
circumference of fixed ring 14 in engagement with the surface
of lower driving portion 26 of each feed wheel 18 mounted from
fixed ring 14 in the first horiæontal plane of rotation. A
second feed belt 32 engages the surface of the corresponding
lower driving portion 26 of feed wheels 19 extendin~ from fixed
rings 14 in the second horizontal plane of rotation. In a
similar manner, a third feed belt 34 engages the surface of lower
driving portion 26 of feed wheels 18 extending from fixed ring 16
and a fourth feed belt 36 engages the circumference of lower
-12-
~153570
driving portion 26 of feed wheels l9 extending from fixed ring 16 in
the third and fourth horizontal planes of rotation, respectively.
Feed belts 30, 32, 34, 36 are shown to be of flat belt
construction, although it should be understood that feed belts
of any suitable construction such as "V" belts, round belts and
the like can be utilized. In fact, as more fully described below,
substantially any type of flexible drive means including chains,
notched belts and the like can be utilized in conjunction with the
feed wheel assemblies 11 without departing from the scope of the
present invention. Since the feed belt does not come into contact ~
with the yarn, it is even possible to use a chain or other
drive belt requiring lubrication since the lubricant would
not contaminate the yarn. Even more significantly, the same feed
belt can be used to drive feed wheels furnishing yarns of
different color or fiber without the feed belt contaminating the
different yarns since the feed belt, at no time contacts the yarn.
Referring to FIGS. 2 and 3, there is provided a drive
frame 38 cantilevered radially outward from the center of the
circular knitting machine by an upper main support 39 mounted
to support column 41, generally in the area of the circular
knitting machine drive motor housing 40. Main drive shaft 42
extends upwardly from drive motor housing 40 and is rotated by a
variable speed drive (not shown). ~lain drive pulley 44 is
journaled to main drive shaft 42 and main drive belt 46,
which is of a "~" ~elt construction in the preferred embodiment,
is rotated by main drive pulley 44. Main drive belt 46 couples
main drive pulley 44 to a quartet of variable pulleys, each
of which is associated with means for driving the first, second,
third and fourth feed belts 30, 32, 34, 36, respectively.
The first, second, third, and fourth variable pulleys 4~, 50,
570
52, 54 are each mounted to one end of corresponding jack
shafts 56, 58, 60 and 62 in a plane of rotation cor~lon to the
plane of rotation of main drive pulley 44. Each jack shaft is
suspended in a substantially vertical orientation by upper and
lower bearing assemblies 64a, 64b mounted to drive frame 38.
In accordance with the present invention, each feed
belt 30, 32, 34 and 36 can be driven at a difrerent peripheral
speed relative to the other belts.
For the sake of illustration, the rotation of
first feed belt 30 will be described. Main drive pulley 44
is connected to the first variable pulley 48 by the main
drive belt 46. First variable pulley 48 is journaled to one
end of the first jack shaft 56 and the first feed belt
pulley 66 is located along the length of first jack shaft
56 and journaled thereto at the height of the first horizontal
plane of rotation. A pair of idler pulleys 68, 68, are xotatably
mounted from idler brackets 70, 70 extending from fixed ring
14. In order to change the speed of rotation of first feed
belt 30 relative to the spe~fl of rotation of main drive
shaft 42, upper and lower flanges 48a and 48b of first
variable pulley 48 are moved axially relative to each other,
thereby changing the radial distance at which the main drive
belt 46 engages the first variable pulley 48. When flanges
48a and 48b are moved closer together, the effective diameter
of first variable pulley 48 is increased resulting in a
decrease speed of rotation of first jack shaft 56 relative
to main drive shaft 42. Conversely, by moving flanges 48a
and 48b further apart, main drive belt 46 engages first
variable pulley 48 at a shorter rate of distance resulting
in higher speed of rotation of first jack shaft 56 and
corresponding increase in the perpendicular speed of first
l~lS357~
feed belt 30.
Second jack shaft 58 contains second variable pulley
50 and second feed belt pulley 72 ~ournaled thereto. Second
drive belt pulley 72 is locatea axially along the length oE
second jack shaft 58 in the second horizontal p~ane of
ro-tation in substantial alignment with the lower driving portion
26 of feed wheels 19 extending from long brackets 22 mounted
on fixed ring 14. Second feed belt 32 is directed over idler
pulleys 68 rotatably mounted from low brackets 78 extending
from fixed ring 14. The third jackshaft 60 contains corresponding
third variable pulley 52 and third feed belt pulley 74
axially located in the third horizontal plane of rotation; and
fourth jack shaft 62 contains fourth variable pulley 54 and
fourth feed belt pulley 76 axially located in the fourth
horizontal plane of rotation. Proper tension is maintained
on thi.rd and fourth feed belts 34, 36 by idler pulleys 68,
68 m~unted to either high bracket 70 or low bracket 78 suspended
from fixed ring 16.
As described above with specifi~ reference to rirst
jack shaft 56 and its associated first variable pulley 48
and first feed belt pull.ey 66, each of the second, third and
fourth variable pulleys 50, 52, 54 are likewise adjustable by
axial movement of their respective flanges. Drive belt idler
pulley 80 is rotatably mounted on swing arm 82 extending from
the bottom of drive frame 38 whereby the position of drive
belt idler pulley 80 can be varied to maintain the proper
tension on main drive belt 46 to assure that there will be no
slippage. The substantially vertical position of main drive
shaft 42 is maintained by support collar 84 extending s~-
3~ stantially horizontally from support.col~n 41.
~ 5357~
The present invention allows each plurality of fcedwheel asse~lies 11 corresponding to a particular yarn
to be fed at constant rates of feed different than the rates
of feed of the other pluralities of yarn feed wheels due primarily
to stitch construction. This feature is also advantageous when
there are differences in the respective yarns due to different
dyes, finishes, size and fiber types.
The construction of the drive frame assem~ly of the
present invention enables this invention to be utilized on a
large variety of circular knitting machines from the coarser
eight cut machines to the finer thirty-two cut machines with-
out substantial modification. Further, the drive assembly
utilizes readily available parts which, with the exception of the
variable pulleys, are commonly used in the knitting industry.
By virtue of the wide range of adjustments possible with the
variable pulleys, the present invention can be used in con-
junction with machines set up for substantially any type of
stitch such as loopin~ stitches requiring more yarn, or tight
stitches requiring the feed of substantially less yarn.
The self actuating positive yarn feed aspect of the
present invention is best shown by reference to FIGS. 4
through 7. In particular, FIG. 4 shows a pair of feed wheel
assemblies 11 each comprising a feed wheel 19, rotatably
mounted from a long bracket 22, mounted on fixed rings 14,
16. In operation, yarn Yb is directed to the top feed wheel
assembly 11 mounted to a fixed ring 14 from a yarn storage
cone (not shown) through a conventional friction device 86.
-16-
115357~?
However, in the present invention pre-friction is not critical.
Yarn ~b is next led through yarn inlet guide 88 mounted in a
fixed yarn guide 89 and wrapped around the cylindrical
surface of upper yarn engaging portion 24 of feed wheel 19.
Yarn Yb exits from the feed wheel assembly 11 through the
yarn outlet guide 90 (best shown in FIG. 5), is passed
through to a conventional stop motion assembly 92, and is
fed to an appropriate yarn finger 94 within striper box 12.
The lower feed wheel assembly 11, suspended from
fixed ring 16, is used to feed yarn Yd from the yarn cone to
the appropriate yarn finger 94 in striper box 12. As is
more fully described below, upper feed wheel assembly 11 is
shown with the yarn Yb in the non-feed position, while lower
feed wheel assembly 11 is in the feed position with yarn
Yd being caused to advance by contact with the upper yarn
engaging portion 24 of feed wheel 19. In such case, yarn
fin~er 94d is activated to allow knitting of yarn Yd.
Feed wheel 18 rotatably mounted from short bracket
20 is shown in enlarged scale in FIG. 5. For clarity, short bracket
20 will be described as being mounted to a segment of fixed
ring 14 so that the feed wheel assembly 11 is driven by first feed
belt 30. It should be understood that FIG 5 could also refer
to a feed wheel assembly 11 suspended from fixed ring 16 and
driven by third feed belt 34.
As shown in FIG. 5, feed wheel 18 is constructed
of upper yarn engaging portion 24 and lower driviny portion 26
separated by central flange 28. The upper yarn engaging portion
24 of feed wheel 18 is defined by the central flange 28 and
l~S3S~o
top flange 96 of feed wheel 18. In accordance with the present
invention, upper yarn engaging portion 24 is Eurth~r divided
into a yarn drive surface 98 and a yarn idle surface 100 on each side
of a medial plane through the upper yarn engaging portion 24
perpendicular to the axis of rotation of feed wheel 18. The
yarn drive surface 98 contains a relatively high friction
material for example, a band of rubber 102 such as Silicone, butyl,
neoprene and the like. The friction between the high friction
surface and yarn Y causes yarn Y to be drawn at a linear
speed substantially identical to the circumferential speed
of the rotating feed wheel 18. Yarn idle surface 100 of
upper yarn engaging portion 24 of feed wheel 18 is constructed
of a material having a low coefficient friction such as
polished metal rods 104 or a smooth, polished cylindrical
surface. When the yarn Y is in contact with yarn idle
surface 100 of feed wheel 18, 19, the low friction between
the yarn and the yarn idle surface allows the yarn to remain
in contact with the rotating feed wheel without having the
yarn advance.
Lower driving portion 26 of feed wheel 18 is
defined by the central flange 28 and the bottom flange 106
of feed wheel 18. The cylindrical surface of lower driving
portion 26 is adapted to be engaged by first feed tape 30
contacting a portion of the circumference of lower driving
portion 26. The circumferential speed of the surface of the
rotating feed wheel 18 is substantially equal to the peripheral
speed of rotation of first feed tape 30.
In accordance with the present invention, yarn inlet
guide 88 mounted in the fixed yarn guide 89 has a bottom exit
surface 108 which defines a substantially horizontal exit
-18-
1~53S~O
plane. The exit plane is above the medial plane dividinc~
the upper yarn engaging portion 24 of feed wheel 18 into the
yarn drive surface 98 and the yarn idle surface 100. In such
case, the yarn Y, when driven by the feed wheel assembly 11
exits from the yarn inlet guide 88 in an orienta-tion substanti.ally
coplanar to the exit plane. As shown in FIG. 6 as the feed wheel
18 is caused to rotate in the direction shown by the arrow,
yarn Y is drawn through yarn inlet guide 88 across bottom exit
surface 108 and onto the forming yarn drive surface 98 of
upper yarn engaging portion 24 of feed wheel 18. As feed
wheel 18 continues to rotate, the yarn is fed in the direction
shown by the arrows.
FIG. 7 depicts yarn Y in the feed position Pf, the
non-feed position Pn and an intermediate position Pi. In
normal operation, yarn Y at each feed wheel assembly 11 is
either in the feed position Pf or the non-feed position Pn.
The intermediate orientation Pi is assumed for a short period
of time while the yarn Y is traveling from the non-feed position
Pn to the feed position Pf. Specifically, when yarn Y is
called for by the appropriate yarn finger in a striper box
or by the needles responsive to the operation of a pattern
wheel, cam or similar device, tension is applied to
yarn Y thereby tightening yarn Y around upper yarn engaging
portion 24. By virtue to the fact that yarn Y is led onto
the upper yarn engaging portion 24 of feed wheel 18 through
the yarn inlet guide 88 having a bottom exit surface 108 at
a height above the medial plane of feed wheel 18, tension
on yarn Y causes the yarn to move from the non-feed position
Pn to the intermediate position Pi. When the yarn Y is in
the intermediate position Pi, yarn Y engages the surface of
the high friction surface and, due to the relatively high
~s3s70
friction between the yarn Y and the high friction surface, yarn
Y is drawn along the high friction surface. Substantially
instantaneously yarn Y moves upwardly as shown by the arrow
and assumes the yarn feed position Pf. As long as there is
tension on yarn Y resulting from the knitting of that yarn,
the friction between the yarn and the high friction surface will
result in positive feed of the yarn.
When there is no longer a demand for yarn Y due to
the change of yarn fingers in the strlper box or changing
demand caused by a pattern wheel or cam, a tensile force is
no longer exerted on yarn Y and the force of the yarn Y
against the high friction surface is substantially minimized
resulting in the yarn Y moving downwardly out of engagement
with the high friction surface into the yarn idle surface 100
of ~he upper yarn engaging portion 24 of feed wheel 18 into
the non-feed position designated Pn. Although it is necessary
for the operation of the present invention that the bottom exit
surface 108 of the yarn inlet guide 88 is above the medial
plane of the upper yarn engaging portion 24, the vertical
orientation of yarn outlet guide relative to the medial
plane is not critical. It has been found that the yarn feed
device of the present invention will generally operate with
the yarn outlet guide located either above, below or at the
medial plane.
In some instances, particularly when the period of
non-feed of the yarn is very short, the yarn may remain above
the medial plane. However, the lack of tension on the yarn
will prevent the h gh friction surface from causing the yarn to
be fed.
In order to obtain optimum operation of the present
-20-
~ JS3~'~0
invention, yarn inlet guide 88 and yarn outlet guide 90 should
be oriented relative to the cylindrical surface oE Eeed wheel
18, 19 so that the yarn Y will engage a sufficient length of
the circumference of the feed wheel to result in the feed of
the yarn at a linear speed substantially identical to the
circumferential speed of the rotary feed wheel. When yarns having
different fibers are used, the orientation of the yarn inlet
guide 88 and yarn outlet guide 90 relative to the feed wheel
18, 19 is varied so that the angle between the points of
tangency of the yarn to the cylindrical surface of the feed
wheel is changed. ~hen the amount of friction between the
high friction surface and the yarn is higher due to the nature
of the yarn or the material comprising the friction surface, the
angle between the points of tangency can be lowered and, con-
versely~ when the amount of friction is lower, the angle may be
lncreased to result in a larger length of the cylindrical surface
engaged by the yarn.
FIG. 8 shows an alternate construction of a multi-
yarn feed wheel assembly 110 having a multiple feed wheel 112
which takes the place of four individual feed wheel assemblies
11. Multiple yarn feed wheel assembly 110 contains a plurality
of yarn engaging portions 124 with a singlc driving portion
126 concentrically mounted on a common shaft 128 for rotation
about the shaft 128 as a single unit.
Feed wheel assembly 110 includes a main support bracket
130 and upper and lower support arms 132, 134 cantilevered from
the main support bracket 130 to support shaft 128 in a sub-
stantially vertical orientation. Each yarn engaging portion 124
~53S~
is defined by two adjacen-t flan(3es 125, 125. Li~e~/Lse, the driving
portion 126, which can be locate~ in the middle of tlle feed
wheel assembly 110 as shown in F:LGS. 8 and 9 or at any other
position between any two yarn engacJin~ portions 12~ or at the top
or bottom of the stack of yarn engaging portions. It should be
understoôd that the multiple feed wheel 112 can be ormed from
a plurality of individual feed wheels journaled tocrether or it
can be fabricated as a unitary assembly. In eithe~ case, multiple
feed wheel 112 rotates as a single unit.
Each yarn engaging portion 124 of multiple feed wheel
112 is separated into a yarn drive surface 136 and a yarn idle
surface 138 on each side of a medial plane through the yarn
engaging portion 124 perpendicular to the axis of shaft 128~ The
yarn drive surface 13~ contains a relatively high friction
surface such as a band or rubber 140 as in the embodiment of this
invention.A fixed yarn guide 142 is associated with each yarn
engaging portion 124 of the multiple feed wheel 112. In the
embodiment of this invention shown in FIGS. 8 and 9, there are
four fixed yarn guides 142. Each fixed yarn guide 142 has a yarn
inlet guide 144 mounted therein with the axis of the yarn inlet
guide 144 in a substantially vertical orienta-tion. The bottom
exit surface 146 of each yarn inlet guide 14~ defines a substantially
horizontal plane at a height above the medial plane of each
corresponding yarn engaging portion 124. Each fixed yarn guide
142 also includes a yarn outlet guide 150. Yarn outlet guide
150 is located adjacent the yarn engaging portions 124 of
multiple feed wheel 112, the specific orientation of the yarn
outlet guide 150 relative to the medial plane is not critical.
22-
In operation, multiple feed wheel 112 of Inultiple
yarn feed wheel asse-llbly 110 is rotated by a drive belt 148
in the direction shown by the arrow in FIG. 8. As best
shown by the top-most yarn Ya in FIG. 9, when there is a
demand for a particular yarn, the requirement for yarn at
the needles puts the yarn under tension maintainin~ the yarn
tightly against the high friction surface on yarn drive
surface 136. As long as there is demand for the yarn! the
self actuating action of the multiple yarn feed wheel assembly
110 will continue to deliver yarn. Ilowever, when there is
no longer demand for that yarn, the tension on the yarn is
released allowing the yarn to substantially instantaneously
move downwardly off the high friction surface along the yarn
drive surface 136, past the medial plane to assume a position
on the yarn idle surface 138 as shown by the orientation of
yarns Yb and Yd in FIGS. 8 and 9. Again, in some instances,
the yarn will remain above the medial plane but the lack of
tension on the yarn will prevent the high friction surface
from causing the yarn to be fed.
The transition of the yarn from the idle or non-
feed position to the drive or feed position is shown by yarn Yc
in FIGS. 8 and 9. Specifically, in a manner similar to that
described with reference to FIG. 7, yarn Yc in FIGS. 8 and 9 exits
from bottom exit surface 146 of yarn inlet guide 144 at a height
above the medial plane of the third yarn engaging portion 124 on
multiple feed wheel 112. Since yarn Yc is now under tension, the
engagement of yarn Yc with the lower corner of the band of
rubber 140 causes yarn Yc to substantially instantaneously move
onto the high friction surface and to ultimately assume the
position shown at the top-most yarn engaging portion 124 of
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multiple feed wheel 112 shown in F~GS. ~ and 9. ~-L substantially
the same time, yarn Ya will move into the orientation shown
for yarns ~b and Yd in FIGS. 8 and 9.
The use of the multiple yarn feed wheel assernbly
110, allows a more compact arrangement for a self actuating mul~iple
yarn feed device. Such device can be simply added to an
existing circular knitting machine having a conventional single
yarn feed and a single drive belt. When the multiple yarn feed
assembly 110 is utilized, however, it is not possible to
independently vary the speed of yarn feed of the individual yarns,
however, this possible disadvantage is overcome by the simplicity
of installation of the multiple yarn feed assembly 110 and the
minimal amount of space required for such assembly.
~ Although not shown, it should be understood that the
present invention can also be utilized with structure comprising
multiple feed wheels having two or three or more than four yarn
engaging portions 124 associated with a single yarn drive surface
130.
The self actuating feature of the present invention
offers many advantages over prior art devices. Most significantly,
this feature of the present invention causes the yarn to be fed
on demand allowing the knitting of more uniform striped or
Jacquard fabric having greater dimensional stability. This
invention can be used in conjunction with striper boxes to
allow the intermittent yet positive feed of the appropriate
yarns in a random order responsive to the operation of the
striper box. Likewise, the present invention can be used in
conjunction with pattern wheels to produce Jacquard patterns
requiring the non-uniform feed of yarn. It has been found
that the appearance and the quality of the fabric are improved
by the positive feed of yarn.
1~ 53S70
When automatic stripincJ machines are use~, it is
necessary .o remove needles in the area of the yarn chz~geover
resulting in the formation of a v~rtical panel ~Ihich is
~enerally known as the selvage or seam. ~enever this seam area
passes over a feed, the fewer needles demand less yarn. Prior
art yarn feed devices, however, typically continue to feed
yarn at a constant rate or respond too slowly to the decrease
in demand resulting in an overfeed of yarn to the needles in
the seam area-and downstream of the seam. Frequently, the
overfed yarn will result in loose stitches often causing
the latches of the needles in the seam area to fail -to open
making a hole or resulting in loose, non-uniform stitches in
the material downstream of the seam. Significantly, the present
invention is capable of responding to the decreased demand
substantially instantaneously thereby avoiding the overfeeding
problem.
Another advantage of the yarn feed device of the
present invention is tha~ when the machine is bein~ set up
initiall~ or restarted after a pressofE or after one o~ more
yarns have broken, there is no need for the operator to manually
override the feed device. Specifically, since the ~arn feed
device of the present invention will not feed yarn unless there
is tension on the yarn, when the knitting machine is operated by
hand, excess yarn will not be fed needlessly which would otherwise
be more susceptible to tangling and subsequently breaking.
The elimination of this problem has been found to substantially
irlcrease the production of fabric on machines utilizing the
present invention. Although some prior art yarn feed devices
can be manually placed in a non-feed posi.ion to avoid these
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1~ S3S7~
;hortcomings, such devices in-trod~1ce anoth~r potent;31 probl~rn.
If the operator does no~ remernber -to restore each fec~l to the
yarn fee~in~ positioII the fabric produced will not be uniform.
The present yarn feed inven-tion has few ~loving parts,
and most significantly, the initial setup requires fe-~, if any,
adjustments. The significant spatial relationship be-tween the
bottom exit surface of the yarn inlet guide relative to the yarn
engaging portion of the feed wheel is set and need not be re-
adjusted.
The yarn feed device of the present invention smoo~hes
out any inconsistencies in pre-tension or tension before the - -
feed device resulting from variations in the winding of the yarn
cone. Unlike many prior art yarn feed devices, such variations in
pre-tension do not affect the operation of the feed device of the
present invention, particularly in the seam, whether or not change-
over occurs. In the present invention, as soon as there is demand
ror yarn at the needles, a preset minimum amount of tension is
applied to the yarn by the needles and a preset rate of yarn will be
detivered by the feed wheel to maintain a uniform level of tension.
20 It has been found that for cotton or poly-cotton yarn knitting, a
jersey stitch, a minimum S grams of tension on the yarn will result
in positive yarn feed. The positive yarn feea is not affected by
any changes in pre-tension.
~ latitude of modification, change in substitution is
intended in the foregoing disclosure and in some instances, some
features of the invention will be employed without a corresponding
use of other features. Accordingly, it is appropriate that the
appended claims be construed broadly and in a manner consis-tent
with the spirit and scope of -the invention herein.
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