BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to a draft device and, more particularly,
to a draft device having belt-driven bottom rollers having adjustable roller gauge
and used in the prespinning process in which a plurality of slivers is drafted by
the draft device used in, e.g., a drawing frame and a comber, and combined into a
strand of sliver.
[0002] In such draft device, the nip distance of the rollers (hereinafter referred to as
"roller gauge") is adjusted depending on the type of fibers to be spun by a spinning
machine. In a draft device whose bottom rollers are driven by a belt, the roller gauge
is adjusted after the belt is loosened and subsequently the tension of the belt is
adjusted to a desired value by a tension adjustment device. When the belt is lengthened
over time, the tension of the belt is also adjusted by the tension adjustment device.
[0003] Published Japanese Translation
H05-502271 of PCT International Publication discloses a draft device for drawing a sliver as shown
in FIG 6. The draft device has drive pulleys 71, 72 that are driven by a flat belt
73 and a deflecting roller 74 provided between the drive pulleys 71 and 72 for changing
the running direction P of the flat belt 73. Tension of the flat belt 73 is adjusted
by another deflecting roller 76 having a tension lever 75 fixed thereto. The tension
lever 75 is pivotally supported on a shaft 77. The deflecting roller 76 is urged through
the tension lever 75 by a spring 78 whose length is set to a predetermined dimension
so that the flat belt 73 is provided with an initial predetermined tension. The position
of the deflecting roller 76 is fixed on the above condition by a clamp screw 79.
[0004] In reducing the tension of the flat belt 73 of the draft device of the above Publication,
with the clamp screw 79 loosened, the tension lever 75 is tilted in the counterclockwise
direction in FIG. 6 against the urging force of the spring 78 thereby to reduce the
tension of the flat belt 73 and then the clamp screw 79 is tightened to fix the tension
lever 75 in its tilted position. The tension lever 75 and the clamp screw 79 are located
below the drive pulleys 71, 72 of the draft device. In a drawing frame and a comber
having the above arrangement, the positions of the tension lever 75 and the clamp
screw 79 are located below the frame to which the bracket supporting the bottom rollers
of the draft device is adjustably mounted, with the result that it is troublesome
to release the urging force of the spring 78 in changing the roller gauge. Additionally,
the adjusted tension of the flat belt 73 may be varied depending on a work person
performing the adjustment.
[0005] The present invention is directed to providing a draft device which allows a work
person to release the tension of the belt easily in roller gauge adjustment and also
to adjust the tension of the belt properly and easily after having adjusted the roller
gauge.
SUMMARY OF THE INVENTION
[0006] A draft device in the prespinning process includes a bottom roller whose roller gauge
is adjustable, a belt for driving the bottom roller, a tension pulley that can urge
the belt downward, a support member for supporting the tension pulley, an urging member
that can urge the support member downward so as to provide a desired tension to the
belt through the tension pulley and an urging force releasing device for releasing
an urging force of the urging member. The urging force releasing device is provided
above the tension pulley so as to be operable above the tension pulley.
[0007] Other aspects and advantages of the invention will become apparent from the following
description, taken in conjunction with the accompanying drawings, illustrating by
way of example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The features of the present invention that are believed to be novel are set forth
with particularity in the appended claims. The invention together with objects and
advantages thereof, may best be understood by reference to the following description
of the presently preferred embodiments together with the accompanying drawings in
which:
FIG. 1 is a schematic side view of a driving mechanism for a back bottom roller of
a draft device according to an embodiment of the present invention;
FIG. 2 is a schematic side view showing the draft device and a coiler according to
the embodiment of FIG. 1;
FIG. 3A is a cross-sectional view taken along the line A-A of FIG. 4 showing a tension
adjustment device;
FIG. 3B is a partially enlarged cross-sectional view showing a cap and a spring of
the tension adjustment device of FIG. 3A;
FIG. 4 is a schematic plan view of the driving mechanism for bottom rollers of the
draft device according to the embodiment;
FIG. 5 is a cross-sectional view of a tension adjustment device according to an alternative
embodiment of the present invention; and
FIG. 6 is a schematic side view of a tension adjustment device according to a prior
art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0009] The following will describe a draft device according to the embodiment of the present
invention with reference to FIGS. 1 through 4. As shown in FIG. 2, the draft device
according to the embodiment is designated generally by numeral 11. A plurality of
slivers supplied from a plurality of combing heads (not shown) or from a plurality
of cans of a drawing frame (not shown) is drafted in the draft device 11 and delivered
to a coiler 13 through a gatherer 12. The draft device 11 is of a three-roller type
having a front bottom roller 14, a middle bottom roller 15 and a back bottom roller
16. A front top roller 17, a middle top roller 18 and a back top roller 19 are provided
at positions corresponding to the front bottom roller 14, the middle bottom roller
15 and the back bottom roller 16, respectively. The bottom rollers 14, 15, 16 and
the top rollers 17, 18, 19 form three pairs of rollers, namely front, middle and back
pairs of bottom and top rollers, respectively. A deflecting roller 20 is provided
in front of the front bottom roller 14 with respect to the traveling direction of
fleece F for changing the traveling direction of the fleece F delivered from the pair
of front bottom and front top rollers 14, 17 to downward movement.
[0010] The coiler 13 includes a coiler trumpet 21, a pair of coiler calendar rollers 22
and a tube wheel 23. The sliver S traveling downward from the gatherer 12 is passed
through the coiler trumpet 21 and the pair of coiler calendar rollers 22 to be pressed
again thereby and delivered into a can 24 by the tube wheel 23.
[0011] The following will describe the driving mechanism for the bottom rollers of the draft
device 11. As shown in FIG. 4, the front bottom roller 14 is rotatably supported between
a pair of brackets 30 and a pulley 31 is fixedly mounted on one end of the front bottom
roller 14 for rotation therewith. As shown in FIGS. 1 and 4, the pulley 31 is driven
by a drive motor 32 through a belt 35 that is wound around the pulley 31, another
pulley 34 provided below the pulley 31 and a drive pulley 33 that is fixed on output
shaft of the drive motor 32 for rotation therewith.
[0012] As shown in FIG. 4, the middle bottom roller 15 is rotatably supported between a
pair of brackets 36 and a pulley 37 is fixed on one end of the middle bottom roller
15 for rotation therewith. The pair of brackets 36 are mounted to the frame (not shown)
by bolts 38 in such a way that the position of the brackets 36 are adjustable in the
direction perpendicular to the axial direction of the middle bottom roller 15. The
back bottom roller 16 is rotatably supported between a pair of brackets 39 and a pulley
40 is fixed on one end of the back bottom roller 16 for rotation therewith. The pair
of brackets 39 are fixed to the frame (not shown) by bolts 41 at a position that is
adjustable in the direction perpendicular to the axial direction of the back bottom
roller 16.
[0013] As shown in FIGS. 1 and 4, the back bottom roller 16 is driven by a drive motor 42
through a belt 48 that is wound around four pulleys 40, 44, 45, 46, a tension pulley
47 and a drive pulley 43 that is fixed on the output shaft of the drive motor 42 for
rotation therewith.
[0014] Like the back bottom roller 16, the middle bottom roller 15 is driven by a drive
motor 49 through a belt 50. As shown in FIG. 4, the drive motors 42 and 49 are disposed
symmetrically with respect to an imaginary line extending across the front, middle
and back bottom rollers 14, 15, 16 at the longitudinal center thereof as seen in FIG.
4. The middle bottom roller 15 is driven by the drive motor 49 through the belt 50
that is wound around four pulleys 37, 52, 53 (one pulley is hidden behind the pulleys
52, 53 in the drawing), a tension pulley 55 and a drive pulley 51 that is fixed on
the output shaft of the drive motor 49 for rotation therewith. For the sake of convenience
of illustration, the driving mechanism for the middle bottom roller 15 is omitted
in FIG. 1.
[0015] The belts 35, 48, 50 are made of toothed belt and the drive pulleys 33, 43, 51 and
other pulleys (e.g. pulleys 40, 45, 46) are made of toothed pulley. All the pulleys
are engaged with and wound around by the toothed belts.
[0016] The following will describe the tension adjustment devices 56, 57 for the belts 48,
50, respectively. Since the tension adjustment devices 56 and 57 are substantially
identical, the following description will be focused on the tension adjustment device
56 for the belt 48. As shown in FIGS. 1, 3A and 4, the tension adjustment device 56
includes a housing 59, a support member 58, a tension pulley 47 and a cylindrical
guide 61 having a small-diameter portion 61A and a large-diameter portion 61 B. The
tension pulley 47 is rotatably supported by the support member 58 that is supported
by the housing 59 in such a way that the support member 58 is movable in vertical
direction relative to the housing 59. As shown in FIGS. 1 and 3A, the support member
58 is formed in L-shape and has formed therethrough in lower part thereof an elongated
hole 58A extending in vertical direction. The guide 61 is fixed to the housing 59
by a bolt 60 (shown in FIGS. 3A and 4) and the guide 61 is engaged at the small-diameter
portion 61A thereof with the elongated hole 58A. The guide 61 is in contact at the
large-diameter portion 61 B thereof with the surface of the support member 58 on the
tension pulley 47 side thereof and the support member 58 is guided vertically in a
manner that the small-diameter portion 61A of the guide 61 slides in the elongated
hole 58A.
[0017] A spring such as a coil spring 62 as the urging member of the present invention is
fixed at the lower end thereof to the upper surface of the support member 58 for urging
the support member 58 downward. The tension adjustment device 56 further includes
a support part 63 that is formed to project horizontally from the upper potion of
the housing 59 and has formed therethrough a screw hole 63A at a position corresponding
to the coil spring 62. A cap 64 is screwed into the support part 63 so that the external
thread 64B of the cap 64 is engaged with the screw hole 63A of the support part 63.
The cap 64 is formed therein with a recess 64A receiving therein the upper portion
of the coil spring 62. In the embodiment, contact of the head of the cap 64 with the
upper surface of the support part 63 serves to prevent the cap 64 from being screwed
in further. The cap 64 has formed in the upper surface of the head thereof a recess
64C that is engageable with the tip of a screwdriver. The cap 64 functions as the
urging force releasing device of the present invention for releasing the urging force
of the coil spring 62.
[0018] The following will describe the operation of the above draft device 11. In the draft
device 11, the front bottom roller 14, the middle bottom roller 15 and the back bottom
roller 16 are driven by the drive motors 32, 49, 42, respectively, at such speeds
that provide the desired draft ratio. A plurality of slivers S is drafted into a plurality
of fleece F at the desired draft ratio and delivered from the paired front rollers.
Subsequently, the plurality of fleece F are passed through the gatherer 12 and the
coiler trumpet 21, collected into a strand of sliver S, pressed again through the
paired coiler calendar rollers 22 of the coiler 13 and delivered into a can 24 through
the tube wheel 23.
[0019] The middle bottom roller 15 and the back bottom roller 16, whose roller gauges are
adjustable, are driven through the belts 48, 50 provided with a desired tension by
the tension pulleys 47, 55 that are urged downward, respectively. The tension pulleys
47, 55 provide the tension to the belts 48, 50 by the coil springs 62 urging the support
members 58 of the tension pulleys 47, 55 downward, respectively.
[0020] In adjusting the roller gauge, the work person releases the urging force of the tension
pulleys 47, 55 on the belts 48, 50, respectively, by removing the cap 64 from the
support part 63. Then, the positions of the back bottom roller 16 and the middle bottom
roller 15 are adjusted by changing the fixing positions of the brackets 39, 36 so
as to adjust the roller gauge to a target value. The work person may remove the cap
64 by putting the tip of the screwdriver in the recess 64C of the cap 64 and turning
the screwdriver. The work person can operate the urging force releasing device easily
for releasing the urging force of the coil spring 62 because the cap 64 as the urging
force releasing device is located above the tension pulleys 47, 55.
[0021] After the roller gauge has been adjusted, the work person screws the cap 64 into
the screw hole 63A of the support part 63 until the external thread 64B of the cap
64 is prevented from being screwed into the screw hole 63A further, in other words,
until the head of the cap 64 comes in contact with the upper surface of the support
part 63. In this state of the cap 64, the tension adjustment devices 56, 57 are set
to a state in which the coil springs 62 urge the tension pulleys 47, 55 through the
support members 58 so as to provide the desired tension to the belts 48, 50, respectively.
[0022] When the belt 48 or 50 is lengthened due to the temporal change, the belt 48 or 50
needs to be replaced by a new one. Alternatively, the coil spring 62 of the tension
adjustment device 56 or 57 needs to be changed to a spring that provide the desired
tension to the lengthened belt 48 or 50 through the support member 58 and the tension
pulley 47 or 55. The tension adjustment device 56 or 57 of the present embodiment
allows the coil spring 62 to be replaced by a new one having a spring constant that
provides the lengthened belt 48 or 50 with the same urging force as that before the
belt 48 or 50 was lengthened. The tension adjustment device 56 of the present embodiment
also allows the cap 64 to be replaced by a new one that is formed with a recess, such
as 64A, having a depth that permits the cap when screwed into contact with the upper
surface of the support part 63 to provide the desired tension to the lengthened belt
48 or 50.
[0023] The draft device 11 according to the embodiment of the present invention offers the
following advantageous effects.
- (1) In the draft device 11, the middle bottom roller 15 and the back bottom roller
16 whose roller gauges are adjustable are driven by the belts 50 and 48, respectively.
The tension adjustment devices 56, 57 of the draft device 11 include the tension pulleys
47, 55 urging the belts 48, 50 downward, and the urging member (or the coil spring
62) urging downward the support members 58 so that the tension pulleys 47, 55 supported
by the support member 58 urge and provide the belts 50, 48 with the desired tension.
The tension adjustment devices 56, 57 further include the urging force releasing devices
(or the caps 64) that are located at a position above the tension pulleys 55, 47,
respectively, and release the urging force of the urging member (or the coil spring
62). Therefore, in adjusting the roller gauges of the middle bottom roller 15 and
the back bottom roller 16, the operations for releasing the tension of the belts 50,
48 and for providing the desired tension to the belts 50, 48 after the adjustment
of the roller gauges can be accomplished without any difficulty.
- (2) The spring (or the coil spring 62) serves as the urging member of the present
invention. A hydraulic damper may be used as the urging member. However, the use of
the spring is advantageous over the hydraulic damper in that the urging member can
be made compact.
- (3) The coil spring 62 forms a part of the tension adjustment devices 56, 57 for providing
the desired tension to the belts 48, 50, respectively, when the coil spring 62 is
urged by the cap 64 engaged with the upper end of the coil spring 62. The cap 64 is
fixed to the support part 63 projecting from the housing 59 in a manner that the external
thread 64B of the cap 64 is engaged with the screw hole 63A of the support part 63
and contact of the head of the cap 84 with the upper surface of the support part 63
prevents the cap 84 from being screwed in further when the desired tension generated
by the coil spring 62 is provided to the belt 48 or 50. When the cap 64 is removed
from the housing 59, the urging force of the coil spring 62 providing the tension
to the belt 48 or 50 is released. When the cap 64 is screwed again into the screw
hole 63A of the support part 63 until the head of the cap 64 contacts with the upper
surface of the support part 63, the cap 64 is prevented from being screwed further
into the screw hole 63A, and then the coil spring 62 urges the support member 58 thereby
to provide the desired tension to the belt 48 or 50. Thus, the embodiment of the present
invention allows any work person to adjust the tension of the belt 48 or 50.
- (4) In case when the belt 48 or 50 is lengthened due to the temporal change, the tension
adjustment of the lengthened belt may be made by replacing the coil spring 62 or the
cap 64 instead of replacing the belt 48 or 50. Therefore, the cost for part replacement
can be made lower as compared with a case of replacing the belt by a new one.
[0024] The present invention is not limited to the above embodiment, but may be practiced
in various ways as exemplified below.
- A hydraulic damper 65 may be used as the urging member of the tension adjustment device,
as shown in FIG. 5. The hydraulic damper 65 is connected with a transfer valve 69.
The transfer valve 69 is selectively connectable through a conduit 67A to an oil tank
66 supplying hydraulic oil to the hydraulic damper 65 at a predetermined pressure
and also to a drain tank 68 through a conduit 67B. When the hydraulic damper 65 is
connected to the oil tank 66 through the conduit 67A, the tension adjustment device
56 hydraulically urges the support member 58 to a position where the support member
58 provides the desired tension to the belt 48 through the tension pulley 47. When
the hydraulic damper 65 is connected to the drain tank 68 through the conduit 67B,
on the other hand, the hydraulic urging force of the tension adjustment device 56
is released. In this case, when the position of the back bottom roller 16 is changed
for adjusting the roller gauge, the positional adjustment of the back bottom roller
16 can be accomplished without any difficulty because of the absence of the tension
to the belt. The transfer valve 69 may be of a hand-operated type having an operation
lever 69A, as shown in FIG. 5. The transfer valve 69 is disposed at such a position
that a work person can operate the operation lever 69A of the transfer valve 69 at
a position that is above the tension pulley 47. The hand-operated valve includes a
detent mechanism (not shown) for keeping the hydraulic damper 65 connected to either
the oil tank 66 or the drain tank 68. The tension adjustment device 57 for the middle
roller belt 50 may have the same structure as the tension adjustment device 56 shown
in FIG. 5. Additionally, in the case when the belt 48 or 50 is lengthened due to the
temporal change, the hydraulic damper 65 connected to the oil tank 66 through the
conduit 67A can urge the support member 58 to a position where the lengthened belt
48 or 50 is provided with the desired tension.
- The transfer valve 69 may be provided by an electromagnetic valve. In this case, the
operating switch of the electromagnetic valve is disposed so that a work person can
operate the operating switch at a position that is above the tension pulley 47.
- The coil spring 62 as the urging member may be replaced by a leaf spring. In this
case, the leaf spring is fixed at the lower end thereof to the support part 63 and
engaged at the upper end thereof with the cap 64. When the cap 64 is screwed into
the screw hole 63A until the cap 64 is brought into contact with the upper surface
of the support member 58, the belt is provided with the desired tension by the leaf
spring.
- When the coil spring is used for the urging member, the lower end of the coil spring
may not be fixed to the support member 58 and only the upper end of the coil spring
may be fixed to the cap 64. In this case, when the cap 64 is removed, the coil spring
is removed together with the cap 64.
- The cap 64 need not be formed with the thread on the entire length of its small diameter
portion. Specifically, no external thread may be formed on part of the cap 64 adjacent
to the tip end thereof and such part is formed with a reduced diameter. In this case,
the number of times of turning the cap 64 until the cap 64 contacts with the upper
surface of the support part 63 is reduced.
- The shape of the recess 64C of the cap 64 need not be slotted, but the cap 64 may
be formed with a Phillips head or a hexagon socket head.
- The structure for fixing the cap 64 to the support part 63 is not limited to the structure
in which the cap 64 is screwed into the screw hole 63A. For example, the cap 64 may
dispense with the external thread 64B and the recess 64C. Instead of the screw hole
63A, the support part 63 may have formed therethrough a hole through which the cap
64 is passed. For holding the cap 64, a retainer may be provided that is movable between
the retaining position for holding the cap 64 and the releasing position for releasing
the cap 64. When the retainer is moved to the releasing position, the cap 64 can be
removed from the hole of the support part 63. When the retainer is moved to the retaining
position, the retainer holds the cap 64 at a position where the support member 58
is urged through the coil spring 62 and the tension pulleys 55, 47 provide the desired
tension to the belts 50, 48, respectively..
- The draft device according to the present invention is not limited to the three-roller
type, but may be of either four-roller type, five-roller type or two-roller type that
is composed of the front roller and the back roller.
- The draft device 11 may dispense with the deflecting roller 20 that is provided in
front of the front bottom roller 14.
- The draft device 11 used in the prespinning process is not limited to a drawing frame
and a comber, but it may be applied to a spinning machine performing a process of
drafting a plurality of slivers into a strand of sliver, e.g., a sliver-wrap machine
or a ribbon-wrap machine.
- The prespinning process may be a process in which a wide fiber bundle (or a web) is
drafted into a sliver, such as carding.
- Instead of the structure in which the urging force of the coil spring 62 is completely
released when the cap 64 is removed, the cap 64 may not be removed when the urging
force is completely released. In this case, the urging force is released in a manner
that the coil spring 62 extends to its free length before the cap 64 is completely
loosened. Alternatively, when the cap 64 is completely loosened, the coil spring 62
extends to a predetermined length and, accordingly, provides small tension that allows
a work person to adjust the roller gauge without any difficulty. In the present invention,
this case is included in the operation of releasing the urging force of the urging
member. In this case, the cap 64 needs not be removed and, therefore, loss of the
cap 64 will not take place and the trouble of reinstalling the cap 64 for providing
the urging force again can be saved.
[0025] A draft device in the prespinning process includes a bottom roller whose roller gauge
is adjustable, a belt for driving the bottom roller, a tension pulley that can urge
the belt downward, a support member for supporting the tension pulley, an urging member
that can urge the support member downward so as to provide a desired tension to the
belt through the tension pulley and an urging force releasing device for releasing
an urging force of the urging member. The urging force releasing device is provided
above the tension pulley so as to be operable above the tension pulley.
1. A draft device (11) in prespinning process comprising:
a bottom roller (15, 16) whose roller gauge is adjustable;
a belt (48, 50) for driving the bottom roller (15, 16);
a tension pulley (47, 55) that can urge the belt (48, 50) downward;
a support member (58) for supporting the tension pulley (47, 55);
an urging member (62, 65) that can urge the support member (58) downward so as to
provide a desired tension to the belt (48, 50) through the tension pulley (47, 55);
and
an urging force releasing device (64) for releasing an urging force of the urging
member (62, 65), characterized in that the urging force releasing device is provided above the tension pulley (47, 55) so
as to be operable above the tension pulley (47, 55).
2. The draft device (11) according to claim 1, characterized in that the urging member (62) is a spring (62).
3. The draft device (11) according to claim 2,
characterized in that the draft device further comprising:
a tension adjustment device (56, 57) adjusting a tension of the belt (48, 50) through
the spring (62), wherein the tension adjustment device including:
a housing (59, 63) having a screw hole (63A); and
a cap (64) engaged with upper end of the spring (62) and having an external thread
(64B), wherein the external thread (64B) of the cap (64) is screwed into the screw
hole (63A) of the housing (59), wherein the tension adjustment device (56, 57) can
prevent the external thread (64B) of the cap (64) from being screwed into the screw
hole (63A) further with the belt (48, 50) provided with the desired tension by the
urging force of the spring (62).
4. The draft device (11) according to claim 3,
characterized in that the tension adjustment device (56, 57) further including:
a guide (61) that is cylindrically-shaped, fixed to the housing (59) and has a small-diameter
portion (61A) and a large-diameter portion (61 B), wherein the support member (58)
having:
an elongated hole (58A) extending in vertical direction, wherein the guide (61) is
engaged at the small-diameter portion (61A) with the elongated hole (58A) so that
the support member (58) is guided vertically.
5. The draft device (11) according to any one of claims 3 through 4,
characterized in that the cap (64) forms the urging force releasing device (64) and further including:
a head, wherein the external thread (64B) of the cap (64) is prevented from being
screwed in further when the head comes in contact with upper surface of the housing
(59).
6. The draft device (11) according to claim 5, characterized in that the urging force releasing device (64) is formed to be no longer removed from the
draft device (11) when the urging force releasing device (64) releases the urging
force of the urging member (62).
7. The draft device (11) according to claim 1, characterized in that the urging member (65) is a hydraulic damper (65).
8. The draft device (11) according to claim 7,
characterized in that the draft device (11) further comprising:
an oil tank (66) supplying hydraulic oil at a predetermined pressure;
a drain tank (68) recovering the hydraulic oil; and
a transfer valve (69) through which the hydraulic dumper (65) is connected to either
the oil tank (66) or the drain tank (68).
9. The draft device (11) according to claim 2,
characterized in that the draft device further comprising:
a tension adjustment device (56, 57) adjusting a tension of the belt (48, 50) through
the spring (62), wherein the tension adjustment device including:
a housing (59, 63) having a hole (63A);
a cap (64) engaged with upper end of the spring (62), wherein the cap (64) is passed
through the hole (63A) of the housing (59), and
a retainer that is movable between a retaining position for holding the cap (64) and
a releasing position for releasing the cap (64), wherein the retainer holds the cap
(64) at a position where the belt (48, 50) is provided with the desired tension by
the urging force of the spring (62) when the retainer is in the retaining position.