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Патент USA US3022035

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Feb. 20, 1962
Filed Aug. 3, 1959
4 Sheets-Sheet 1
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Feb. 20, 1962
E. J. SAXL '
Filed Aug. 3, 1959
4 Sheets-Sheet 2
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324mm JISaJGZ,
Feb. 20, 1962
Filed Aug. 3, 1959
4 Sheets-Sheet 5
Feb. 20, 1962
Filed Aug. 3, 1959
4 Sheets-Sheet 4
United States Patent Office
Patented Feb. 20, 1962
inertia, a braking device for applying varying amounts
Erwin J. Sax], Harvard, Mass, assignor to Tensitron, Inc,
Harvard, Mass, a corporation of Massachusetts
Filed Aug. 3, 1959, Ser. No. 831,352
8 Claims. (Cl. 242-155)
of drag to the wheel, and a replaceable cover for the
wheel made of elastic material and having a groove in
which the ?lament is engaged. The cover preferably has,
in the groove, transverse serrations which provide good
traction between the wheel and the ?lament but are yield
able to avoid crimping the ?lament. The device is pref
erably provided with a stop mechanism which stops the
wheel, when the winding or other machine is stopped, to
This invention relates to devices for controlling the
running tension of yarn, Wire and similar ?lamentary 10 prevent overrunning.
materials during such operations as knitting, weaving,
In the drawings illustrating the invention:
de-reeling, or winding. This application is a continua
FIG. 1 is a front view, with part of the casing broken
tion-in-part of the inventor’s copending application Serial
No. 511,202, ?led May 26, 1955, now abandoned.
The control of tension of a running ?lament is of ut 15
most importance in many operations. In the textile ?eld,
for example variations in tension of the yarn during the
various yarn preparatory operations results in ?aws in the
cloth, uneven selvages, non-uniform load distribution over
the individual components, such as the strands or shrouds
of parachutes, cordage and the like, with resulting impair
ment to shock load strength, and other defects. When
away, of preferred form of a tension control device con
structed according to the invention;
FIG. 2 is a cross-section taken along line 2—2 of FIG. 1;
FIG. 3 is a fragmentary cross-section, somewhat en
larged, taken along line 3-3 of FIG. 1;
FIG. 4 is a fragmentary cross-section, somewhat en
laroed, taken along line 4—4 of FIG. 1;
FIG. 5 is a side view of the tension wheel;
FIG. 6 is a rear elevation of the wheel;
FIG. 7 is a rear view of one form of expendable cover
synthetic yarns are used, excessive tension, though below
the breaking point of the yarn, may result in a permanent
for the wheel;
deformation which changes the dye absorption and light
larged, taken along line 8--8 of FIG. 7;
FIG. 9 is a side elevation, partly in cross-section, of
re?ecting characteristics of the yarn. In wire handling
FIG. 8 is a fragmentary cross-section, somewhat en
operations, for example, in winding coils for precision
an alternate form of expendable cover;
electrical components, it is essential to maintain correct,
FIG. 10 is an electrical schematic diagram of a circuit
uniform tension in order to produce coils of uniform
for energizing the drag magnet;
electrical characteristics. Variation in the tension on the 30
FIG. 11 is a horizontal, fragmentary cross-section of a
wire during winding will result in tighter or looser wind
modi?cation of the control device, taken in the same gen
ing and therefore variation in the number of ampere
eral region as FIG. 3;
turns between one coil and another. If the wire is
FIG. 12 is a fragmentary cross-section taken along line
stretched beyond its elastic limit, its diameter is perma
12—12 of FIG. 11; and
nently reduced and its ohmic resistance is increased. Such 35
HG. 13 is an end elevation, on a somewhat reduced
defects, in a lamp or tube ?lament for example, will
scale, of the control device of FIG. 11.
produce “hot spots” and cause the ?lament to burn out
As shown in FIGS. 1 through 4, the various parts of
before its normal life or load limit is reached. Control
the device are supported on a casing 20 having a front
of tension is especially important when winding ?ne
plate 20a and are enclosed at the rear by a cover plate 21.
enamelled wire, such as that commonly used for coils in to The casing is mounted in any convenient manner, for ex
electrical components. Excessive stretching, even though
ample by means of a post 22 and clamp block 23 above
the tension is within the elastic limit of the wire itself,
a bobbin holder 24, containing a bobbin 25 of conventional
produces “crazing,” or microscopic cracks, in the insula
type from which the yarn, wire or other ?lamentary mate
tion which is less elastic than the wire. This condition is
rial 26 is to be run off overhead.
likely to cause short circuits in the coil.
A dancer arm 27 is pivoted by a pin or shaft 28 to a
Magnetic recording tape is also very sensitive to vari
block 29 secured to the under side of the casing 20. The
ations in tension, both in recording and reproducing. In
dancer-arm carries three grooved guide pulleys 3t), 31 and
sound reproduction systems, such variations produce dis
32, and is normally urged upward by means of a tension
tortion. In computing and data handling systems, the
spring 33 connected to an adjusting screw 34 mounted on
accuracy of the equipment is affected by variations in 50 a bracket ‘35 on the casing. Mounted on the dancer arm
tape tension.
is a block 36 to which is attached a flux gate 37 of mag
Changes in tension in a running yarn or wire are caused
by a number of factors such as variation in speed of the
motors which drive the winding or other mechanism,
starting and stopping, change in diameter of the winding 55
and unwinding reels as the material is run olf, or the non
mounted on a shaft 41 which runs through a bearing 42
circular shape of a core on which the material is being
wound, as in winding square or rectangular coils.
The principal object of this invention is to provide a
netically permeable material. This gate extends upward
into the casing through a slot 38 in the bottom of the
A wheel, generally indicated by the numeral 40, is
in the front wall 20a of the casing. Mounted behind the
Wheel is a stationary guard 43. A ring-shaped cover,
generally indicated by the numeral 44, is mounted on the
simple and effective device for maintaining substantially 60 wheel. Secured to the shaft 42 behind front Wall 20a
constant tension on a running ?lament under various
is a hollow drum 45, having a rearwardly extending, ex
operating conditions. Another object is to provide a de
ternally threaded, ?ange 45a. A tubular drag cup 46 of
vice which may be used on delicate ?laments, such as
magnetically permeable material is internally threaded
?ne synthetic or glass yarns or insulated wires without
and screwed on to the outside of drum ?ange 45a. [Drag
danger of damage to the material. Still another object is
65 cup 46 has a radially projecting flange 46a by which the
to provide a means of readily adjusting the tension for
cup can be grasped to turn it to adjust its position axially.
different requirements. Another object of the invention is
Mounted in the casing in any suitable manner, for ex
to stop the ?lamentous material quickly when the winding
ample by bolts 59, is a stack of generally U-shaped mag
or other machinery is stopped. Other objects, advantages,
netic laminations 51. A coil 52 is mounted on these
and novel features of the device will be apparent from
laminations and has leads 53 and 54 passing out through
the following description.
the casing. These laminations each have a long upper
The device consists, in general, of a drag wheel of low
leg 51a which extends over the top of cup 46' and a
shorter lower leg 51b. Another stack of laminations 55
is connected to legs 51b by means of non-magnetic bridg
ing plates 56 and 57, and extend around the lower part
of cup .46. -Laminations 55 ‘and-the leg vparts 51a of
laminations 51 are joined together on each side of cup 46
by magnetic bridging pieces 58 and 59, so that the whole
of the recti?er bridge is put through a potentiometer 76
and the coil 52. Resistor 74 provides the “range” or
coarse adjustment, and potentiometer 76-provides ?ne ad
justmeut of the current through coil 52.
The operation of the device is as follows:
The ?lament 26 is led around the groove in the cover
of wheel 45 and around guides 30 and 31, as shown in
FIG. 1. These guides hold the ?lament in contact with
assembly forms a magnetic core having a generally cir
cular gap 60 in which cup 46 revolves, and a straight gap
the wheel cover around a considerable part of its pe
61 in which gate 37 moves. up and down. A stack of
circular laminations 62 is mounted inside cup 46. These 10 riphery. The ?lament is led over guide pulley 32 and
from there passed to the Winding or other device. The
laminations are supported by bolting them to an exten~
amount of drag to produce the desired amount of- tension
sion of plate 57. It is understood that the clearance be
on the ?lament is set by means of resistors 74 and 76 and
tween cup 46 and the inner and outer sets of laminations
can also be adjusted by screwing cup 46 in or out along
is somewhat exaggerated in the drawings for clarity. It is
desirable to make the clearance as small as practicable in 15 drum 45 so as to change the depth to which the cup
enters the gap 60 in the magnet core assembly. Pref
order to obtain maximum e?iciency of the magnetic cir
erably, the ?nal adjustments ot-the tension are made
while the machine is running.
A hinge leaf 63 is secured to the leg part 51a of lami
Under the running tension, arm 27 is pulled down
nations 51 and is hinged to an armature 64 made of mag
netic material. The armature carries a yoke 65 which 20 somewhat and gate 37 is partially out of gap 61. An in
crease in tension will cause arm 27 to be pulled down
surrounds drum 45. Armature 64 is urged upward by a
further, drawing gate 37 further out of gap 61. This
tension spring 66, and yoke 65 carries a brake shoe 67
reduces the magnetic ?eld and consequently the drag on
which engages drum 45. When coil 52 is energized, the
cup 46,. restoring the tension to normal. If the tension
magnetic ?eld of the core assembly draws armature 64
drops below normal, arm 27 rises, causing gate 37 to
down and disengages the shoe from drum 45.
close more of gap .61, and the magnetic drag and re
The wheel 40, shown in detail in FIGS. 5 and 6, is
sulting tension are increased. Because of the extremely
made of light weight plastic or aluminum, and has a for
low inertia of the wheel assembly, the ‘response of the
wardly sloping rim 40a, and a’ number of spaced openings
device is practically instantaneous, so that the tension is
4011 from which tabs 400 are bent toward the rear, form
ing with the rim a discontinuous V-shaped peripheral 30 kept uniform within close limits.
elastomeric materiah'such as rubber. The layers are of
As previously stated, the energizing circuit forcoil 52
preferably. includes the starting switch of the machine.
Therefore, the coil becomes deenergized whenever the
machine is stopped, and the brake mechanism, consisting
of armature 64 and yoke 65, goes into operation to stop
the wheel. This positive braking action prevents the ?la
ment from overrunning and building’ up slack, which
contrasting colors so that it will be immediately apparent
might result in a loose coil on a coil winding machine,
when the outer layer has worn through and the cover
should be replaced. The cover has a pair of hollow 40
for example.
groove 40d.
The wheel has a hub 40c and may have
radial sti?ening ribs 40]‘. The wheel is rigid enough to
withstand considerable tension from the wire or yarn pass
ing around it, but is yet of extremely light weight. One
form of wheel cover 44, shown in FIGS. 7 and 8, is
formed of inner and outer layers 44a and 44b of soft
?anges 44c and 4444’, which ?t around rim 40a and tabs
49c, respectively, and de?ne a V-shaped groove 44a. As
shown in FIG. 3, the cover has small transverse ribs 44;‘
in the groove.
An alternative form of cover 70 is shown in FIG. 9.
This cover has the same general shape as that of FIGS.
7' and 8, with hollow flanges 70a and 70b de?ning a V
shaped groove 700, but is made of a ribbed knit material
with the ribs 79d disposed preferably cross-wise, to pro
vide good traction. The cover may be formed by cutting
oii a piece of tubular knit material, impregnating it with,
latex or mild sizing and placing it to dry on a suitably
shaped mandrel. The rubber cover is best for wire, and
The device can, if desired, be used as a ?xed drag de
vice by locking arm27 to the casing in any convenient
manner, or simply by running the ?lament around the
wheel and guides 39, 31 only, skipping guide 32. In op
erations which do not cause appreciable ?uctuations in
the running tension of the ?lament, using thedevice in
this manner may be satisfactory.
For some purposes it is desirable to connect a revolu
tion counter ?t to shaft 41 to measure the amount of
material which is run over the wheel. For example, in
Winding coils for eleotricial components it is desirable
to maintain accurate control over the number of turns.
The counter can be calibrated to indicate the number
of tunns. ' By controlling the tensions, as well as the
the knit cover for delicate yarns which are very slippery,
number of turns, the electrical characten'stics'of coils
such as nylon, or other synthetics. When using a knit 55 can be controlled with a high degree of precision.
tubular cover, selvages are preferably cross-knit into the
in the modi?ed formof the device shown in FIG. 11,
knitted tubing from which the covers are made so that
individual covers can be cut off without unravelling.
the Wheel and drag cup assembly are the same as in the
form previously described.‘ The magnetic core is made
up of a stack of M-shaped laminations v80 having central
?lament. The ribs increase the traction but, being made 60 legs 85a and short side legs 80b and Silo. ‘ Two stacks of
of relatively soft elastic material, do not crimp or dam
laminations 81 and Y82 are mounted alongside the‘ ends of
age the ?lament. This is especially important in the case
In all cases the cover provides good traction for the
of ?ne wire which, is likely to become jpermanently
legs 8% and "800, respectively, forming gaps 83 and 84.
in place of coil 52, and the device operates in essentially
Arm 27 carries angles 85'and36 which extend up through
orimped when run over rigid “Washboard” wheels of con
ventional type. For use with corrosive ?laments or ?la 65 slots 87 and ‘88 in the casing and form ?ux gates in gaps
83 and 84. The excitingcoil 89 iswound around legs
ments having a corrosive coating, a cover similar to that
Sila. This coil is connected in the circuit of FIG. 10
of FIG. 9 made of ?ne stainless steel mesh may be em
A circuit for'energizing the coil 52 is shown in FIG.
the same’ manner as that previously described, gates 85
10. A pair of terminals 71, 72 are connected to a power
source, which may be AC. or D.C., for example the
on cup 46 as arm 27 moves in response to variations in
source for operating the winding ‘or other machine. The
circuit includes a switch 73, which may be the start and
stop switch of the machine, a variable resistor 74, and a
and 86 moving up and downto alter the magnetic drag
For applications where only a small range of tension
adjustment is required, a permanent magnet may be used
recti?er bridge 75, all connected in series.’ The output 75 in place’ of the electromagnet assembly. Adjustment of
the wheel drag is made entirely by changing the position
posed in one of said end legs, and the other end leg
of the drag cup.
having a third gap, said dancer arm carrying a second
gate movable in and out of said third gap.
The wheel is preferably made as small as feasibly con
sistant with providing enough surface for the ?lament to
run on to supply the necessary traction without damage
to the ?lament. A wheel of 2 to 21/2 inches in diameter
is suitable for most ?ne yarns and wires. The drum and
cup are made as light as possible so that the whole run
5. A device, for controlling tension of a running ?la
ment, comprising a rotatable Wheel assembly including
a wheel, a member having a brake receiving surface, and
a magnetically permeable member, said wheel having a
peripheral surface adapted to engage said ?lament, an
electromagnet creating a magnetic ?eld in which said
ning assembly has a low inertia. This is important not
only to achieve fast response to changes in the magnetic l0 permeable member rotates, means for energizing and de
energizing said electromagnet, a movable armature
?eld but also to prevent breakage of delicate ?laments in
The entire device is relatively inexpensive. The ex
endable covers can be replaced at very little cost and
adapted to move toward said magnet when the magnet is
energized, means for moving said armature away from
said magnet when the magnet is deenergized, and a brake
are slipped on and ed without dismantling or a?ecting 15 member carried by said magnet and disposed to fric
the setting of the device. The device is thus practicable
for controlling individual thread tension, in multiple sta
tion machines, such as multiple coil winders for example.
The term “?lament” is here used in the speci?cation
tionally engage said brake receiving surface when said
magnet is deenergized.
6. A device, for controlling tension of a running ?la
ment, comprising a wheel having a peripheral surface
and claims in a general sense and is intended to include
adapted to engage said ?lament, a brake drum and a
multiple as well as single strand yarns, wires, tapes and
other ?lamentous materials. The device may be adapted
for tape tension or ?lm tension control simply by Widen
ing the bases of the grooves in the wheel and cover.
This will reduce shock tensions on ?lms, tape, and the
like, such as occur in the start-and-stop motion of mov
magnetically permeable member attached to and rotat
able with said wheel, an electromagnet adapted to create
a magnetic ?eld in which said permeable member rotates,
means for energizing and deenergizing said magnet, an
armature hinged to said magnet and disposed to be
drawn toward said magnet when the magnet is energized,
ing picture—cameras and projectors as well as in the rapid
a spring adapted to move said armature away from said
acceleration and stopping, respectively, of data-handling
equipment based upon magnetic recording and locating
devices of magnetizable tape and wire. By reducing
magnet when the magnet is deenergized, and a brake
member cmied by said armature and adapted to fric
30 tionally engage said drum when said armature is moved
shock tensions as outlined above, tension peaks can be
away from said magnet and to be disengaged from said
reduced and the tape thus can be engineered to run
drum when said armature is drawn toward said magnet.
safely at lower breaking strength resulting in the safe use
7. A device for controlling tension of a running ?la
of thinner tapes and larger capacity of the tape drums.
ment, comp-rising a supporting member, a wheel rotatably
35 mounted on said member and having a peripheral surface
What is claimed is:
1. A device, for controlling tension of a running ?la
adapted to engage said ?lament and an axis of rotation,
ment, comprising a supporting member, a wheel rotatably
a substantially tubular drag cup of magnetically perme
mounted on said member and having a peripheral sur
able material disposed concentrically with respect to said
face adapted to engage said ?lament, means for main
wheel, a magnet mounted on said supporting member and
taining said ?lament in contact with said surface, a mag
having a ?rst gap in which a portion of said cup is dis
netically permeable member attached to and rotatable
posed, and a second gap, said magnet being disposed in
?xed position with respect to said wheel axis, an adjustable
connection between said cup and said wheel providing
permeable member being rotatable in said ?rst gap and
movement of said cup along said axis toward and away
braked by the ?eld of said magnet, a dancer arm mounted 45 from said wheel, whereby the portion of said cup disposed
on said supporting member and having means engaging
in said ?rst gap can be varied, a dancer arm mounted on
said ?lament, said arm being movable in response to
said supporting member and having means engaging said
variations in tension of said ?lament, and a gate of mag
?lament, said arm being movable in response to variations
netic material mounted on said dancer arm and extending
in tension of said ?lament, and a gate of magnetic ma
into said second gap and disposed to be moved in and 50 terial mounted on said dancer arm and extending into
out of said gap by movement of said dancer arm, thereby
said second gap and disposed to be moved in and out of
varying the braking e?ect of said magnet on said perme
said second gap by movement of said dancer arm, thereby
able member.
varying the braking eifect of said magnet on said perme
2. A device as described in claim 1, said permeable
able member.
member being of generally tubular shape, and said mag 55
8. A device as described in claim 7, said connection
net having portions disposed inside and outside said
comprising a drum attached to said wheel and threadably
permeable member.
engaged with said cup.
3. A device as described in claim 1, said permeable
member being of generally tubular shape and said mag
References Cited in the ?le of this patent
net including a generally rectangular portion disposed 60
to surround said member and a generally cylindrical por
Wardwell _____________ __ June 5, 1900
tion disposed inside said member, and said second gap
with said wheel, a magnet mounted on said supporting
member and having a ?rst gap and a second gap, said
being disposed in said rectangular portion.
4. A device as described in claim 1, said permeable
member being of generally tubular shape, and said mag 65
net having a central leg extending inside said permeable
member, and a pair of end legs disposed on opposite sides
of said permeable member, said second gap being dis
2,73 8,937
Klein et al ____________ _._ July 19, 1938
Roughsedge __________ __ Mar. 20, 1956
Levine _______________ __ Oct. 30, 1956
France _______________ _.. Dec. 10, 1956
France _____._. _____ _.____.__ NOV. 24, 1958
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