Background of the Invention
Field of the Invention
[0001] The present invention relates to a device for detecting looseness in the drafting
rollers of a spinning machine and, more specifically, to a device for detecting looseness
in the drafting rollers of a spinning machine equipped with a drafting device which
is equipped with a plurality of bottom rollers each consisting of a plurality of roller
shafts connected with each other through threaded engagement of screw portions formed
at the ends thereof, each bottom roller being divided into two line shafts and arranged
coaxially, each line shaft being driven from the machine base end side.
Description of the Related Art
[0002] In a spinning machine such as a ring sinning machine, roving supplied from a roving
bobbin is drafted by a drafting device and sent out from a front roller before it
is taken up by a bobbin rotating integrally with the spindle by way of a snail wire,
an anti-node ring, and a traveler traveling on the ring.
[0003] Generally speaking, as shown in Fig.5, a drafting device 51 is of a three line type
consisting of front roller 52, middle roller 53, and back roller 54, and as shown
in Fig.4, front bottom roller 52a, middle bottom roller 53a, and back bottom roller
54a are driven by a single motor 55.
[0004] Further, generally speaking, as shown in Fig. 6, each of the bottom rollers 52a through
54a consists of a plurality of roller shafts 56 which are connected with each other
through threaded engagement of male screw portions 56a and female screw portions 56b
formed at the ends thereof so as to be formed into a single line shaft. And, the fastening
direction of each screw is generally determined according to the direction of the
load received by each of the bottom rollers 52a through 54a. Thus, each of the bottom
rollers 52a through 54a adapted to draft and send out roving R are designed so as
to be fastened when rotated in the fiber bundle (roving) sending out direction (counterclockwise
in Fig. 5).
[0005] Further, recently, there is a tendency for the machine base to have a large number
of spindles (e.g., 400 to 600 spindles on one side). In view of this, an apparatus
has been proposed and put into practical use in which a driving motor is provided
at either longitudinal end of the machine base and in which each bottom roller of
a drafting device is divided substantially at the center into two line shafts, each
line shaft being driven from the machine base end side. Also in the construction in
which each bottom roller is divided into two line shafts, the spindle pitch is entirely
fixed, so that the gap between the opposing end surfaces of the line shafts is as
small as several mm to around 10 mm.
[0006] It is to be noted, however, that, as shown in Fig. 5, the load acting on the back
roller 54 of the drafting device 51 is a resultant force of a reaction force F1 for
drawing in roving R and a pulling force F2 applied by the middle roller 53 through
the fiber. And, since the forces F1 and F2 are in opposite directions, the load acting
when rotating the back bottom roller 54a fluctuates depending upon the magnitude relationship
between the forces F1 and F2. And, when a large difference is generated in the load
acting on the roller shafts 56 constituting the back bottom roller 54a due to non-uniformity,
etc. of the roving supplied to each spindle, relative rotation is generated between
the roller shaft 56 under large load and the roller shaft 56 under small load, so
that there is the possibility of a force causing looseness in the screws being exerted.
When looseness is generated, not only does the drafting fail to be conducted at a
predetermined drafting ratio, but also the back bottom roller 54a expands. And, any
looseness generated is likely to augment with the result that the looseness amount,
that is, the expansion, increases and that the opposing end surfaces of the divided
back bottom roller 54a interfere with each other, resulting in damage to the parts.
Summary of the Invention
[0007] The present invention has been made in view of the above problem in the prior art.
It is an object of the present invention to provide a device for detecting looseness
in drafting rollers of a spinning machine for use in a drafting device of the type
in which a bottom roller consisting of a plurality of roller shafts connected to each
other through threaded engagement of screw portions formed at the ends thereof is
divided into two line shafts and in which each line shaft is driven from the machine
base end side, wherein it is possible to detect generation of looseness in the screw
portions of the roller shafts.
[0008] To achieve the above object, according to this invention, each bottom roller consists
of a plurality of roller shafts connected to each other through threaded engagement
of screw portions formed at the ends thereof, and is divided in the longitudinal direction
into two line shafts. The line shafts are arranged coaxially, and driven from the
machine base end side. And, there is provided detecting means which detects looseness
in the roller shafts on the basis of rotation or axial movement of that roller shaft
of the plurality of roller shafts constituting the back bottom roller which is situated
at the end on the side opposite to the driving side.
[0009] In this invention, relative rotation is generated in the roller shafts in a condition
in which the difference in the load acting on the plurality of roller shafts constituting
the back bottom roller divided into two line shafts has become large. And, when looseness
is generated in at least a part of the roller shafts, that roller shaft which is situated
at the end on the side opposite to the driving side moves (rotates) to the loosened
side, and its axial movement or rotation to the loosened side is detected by the detecting
means. Thus, on the basis of a detection signal therefrom, it is possible to take
appropriate measures, such as the stopping of the machine base.
[0010] It is also possible for the detecting means to detect the looseness on the basis
of rotation of the roller shaft situated at the end on the side opposite to the driving
side. In this invention, looseness in the roller shafts is detected on the basis of
rotation of the roller shaft situated at the end on the side opposite to the rotating
side of the line shaft. Rotation due to looseness in any one of the plurality of roller
shafts constituting the line shaft is reflected in the roller shaft situated at the
above-mentioned end, so that by detecting rotation of that roller shaft, it is possible
to detect generation of looseness in the roller shafts constituting the line shaft.
In the arrangement in which axial movement of the above-mentioned roller shaft is
directly detected, the gap between the line shafts is small, so that it is difficult
to accurately detect movement that is attributable to looseness in the screw portions
while excluding the influence of expansion of the line shafts due to thermal expansion.
However, in the arrangement in which rotation of the roller shaft is detected, it
is possible to perform detection with sufficient accuracy even if the moving amount
of the roller shaft per rotation of the roller shaft is small.
[0011] It is also possible for the detecting means to detect the above-mentioned looseness
on the basis of relative rotation between the roller shaft situated at the end on
the side opposite to the driving side and the roller shaft situated at the driving
side end. In this invention, the position of the driving side end of the line shaft
is used as a reference, and looseness in the roller shafts is detected on the basis
of relative rotation of the roller shaft situated at the end on the side opposite
to the driving side with respect to it. Thus, looseness in any roller shaft causes
relative rotation of both roller shafts, and as compared to the detecting method based
on the relative rotation of the roller shafts provided at the ends of the two line
shafts whose end surface are opposed, an improvement is achieved in terms of detection
accuracy.
[0012] It is also possible for the detecting means to detect the above-mentioned looseness
on the basis of relative rotation between opposing roller shafts situated at the end
on the side opposite to the driving side. In this invention, it is possible to detect
looseness in the roller shafts constituting one back bottom roller using two sensors.
In a case in which both line shafts are loosened simultaneously and in the same manner,
the above-mentioned roller shafts make no relative rotation, and it is impossible
to detect the looseness. However, this does not lead to any substantial problem since
the probability of both line shafts loosening in the same manner is very low.
[0013] In a spinning machine in which a pair of drafting devices as described above are
provided on the right and left sides, the above-mentioned detecting means is provided
in each of the drafting device.
[0014] In a spinning machine in which a pair of drafting devices as described above are
provided on the right and left sides, the above-mentioned detecting means is provided
in each of the drafting device, and the detecting means detect the above-mentioned
looseness on the basis of rotation of four roller shafts situated at the end on the
side opposite to the driving side. Thus, in this invention, a further improvement
is achieved in terms of detection accuracy.
[0015] The detecting means may be provided with a proximity switch as the detecting portion,
and the roller shaft on the portion-to-be-detected side may be provided with one or
more recesses such that its section in the portion corresponding to the proximity
switch is recessed relative to the section around the same.
[0016] Further, the detecting means may be provided with a proximity switch as the detecting
portion, and the roller shaft on the portion-to-be-detected side may have a substantially
D-shaped section in the portion corresponding to the proximity switch. In this invention,
the possibility of erroneous detection due to the influence of lint is lower as compared
with the case of the detecting portion which detects any photoreception or the photoreception
amount of the photoreceptor portion as in an optical sensor. Further, since the section
of the roller shaft portion constituting the portion to be detected has a substantially
D-shaped sectional configuration, the portion to be detected is not in the way when
arranging the guide plate for the fiber bundle on the downstream side of the back
bottom roller as in the case in which the portion to be detected protrudes from the
peripheral surface of the circular portion.
Brief Description of the Drawings
[0017]
Fig. 1 is a schematic plan view of a drafting device according to an embodiment of
the invention;
Fig. 2a is a partially sectioned plan view showing how roller shafts are connected
to each other, Fig. 2b is a schematic end view taken along the line B-B of Fig. 2a,
and Fig. 2c is a schematic end view corresponding to Fig. 2b, showing the driving
side end of a roller shaft;
Fig. 3 is a graph showing the output pulses of proximity switches;
Fig. 4 is a schematic plan view of a conventional drafting device;
Fig. 5 is a schematic side view of a drafting device; and
Fig. 6 is a partially sectioned plan view showing how roller shafts are connected
to each other.
Description of the Preferred Embodiment
[0018] In the following, an embodiment of the present invention applied to a spinning machine
in which a pair of drafting devices are provided on the right and left sides will
be described with reference to Figs. 1 through 3. Fig. 1 is a schematic plan view
of a drafting device in which top roller is omitted.
[0019] As shown in Fig. 1, a drafting device 11 is of a three-line type construction equipped
with a front bottom roller 12, a middle bottom roller 13, and a back bottom roller
14 as the drafting rollers. Each of the bottom rollers 12 through 14 is divided into
two line shafts: 12a and 12b, 13a and 13b, 14a and 14b, and the line shafts of each
pair: 12a and 12b, 13a and 13b, 14a and 14b are arranged coaxially. The line shafts
12a through 14a and 12b through 14b are each driven from the ends of the machine base
by driving motors 15a and 15b.
[0020] The line shafts 12a through 14a are operationally connected by a gear row (drive
gearing) (not shown) contained in a gear box 16a arranged at one end of the machine
base. The line shafts 12b through 14b are operationally connected by a gear row (drive
gearing) (not shown) contained in a gear box 16b arranged at the other end of the
machine base. Rotation of the driving motors 15a and 15b is transmitted to the gear
boxes 16a and 16b through a belt transmission mechanism 17. The driving motors 15a
and 15b are speed-change controlled by a machine base control device 19 through an
inverter 18.
[0021] As shown in Fig. 2a, each of the line shafts 12a through 14a and 12b through 14b
consists of a plurality of roller shafts 21 connected to each other through threaded
engagement of male screw portions 21a and female screw portions 21b formed at the
ends thereof. Fig. 2a shows the line shafts 14a and 14b of the back bottom roller
14. Of the roller shafts 21, both roller shafts 21 situated at the end on the side
opposite to the driving side are supported by bearings 20a at opposing ends thereof.
Further, the roller shafts 21 are supported by bearings 20b in the vicinity of the
connecting portions thereof.
[0022] The back bottom roller 14 is equipped with detecting means for detecting looseness
in that roller shaft 21 of the plurality of roller shafts 21 constituting the back
bottom roller 14 which is situated at the end on the side opposite to the driving
side. The detecting means is designed so as to detect looseness in the roller shafts
on the basis of rotation of the roller shaft 21 situated at the end on the side opposite
to the driving side. In this embodiment, the above-mentioned looseness is detected
on the basis of relative rotation of the roller shaft 21 situated at the end on the
side opposite to the driving side and the roller shaft 21 situated at the driving
side end.
[0023] In this embodiment, the detecting means is equipped with proximity switches 22a and
22b as detecting portions arranged at positions corresponding to the roller shaft
21 situated at the end on the side opposite to the driving side of the line shafts
14a and 14b and proximity switches 23a and 23b (See Fig. 1) as detecting portions
arranged at positions corresponding to the roller shaft 21 situated at the driving
side end. The roller shafts 21 situated at the driving side ends of the line shafts
14a and 14b are free from looseness, so that one proximity switch 23a, 23b is provided
for each of the line shafts 14a and 14b that each consist of two line shafts.
[0024] Further, as shown in Figs. 2b and 2c, each of the roller shafts 21 on the portion-to-be-detected
side has a substantially D-shaped sectional configuration at a position corresponding
to the proximity switch 22a, 22b, 23a, 23b, with a flat portion 21c being formed in
a part of the cylindrical peripheral surface. The positions of the flat portions 21c
are determined such that there is a phase deviation of 180 degrees between the positions
corresponding to the proximity switches 22a and 22b and the positions corresponding
the proximity switches 23a and 23b. Thus, when the roller shafts 21 rotates in a connecting
condition free from looseness, rotation of the back bottom roller 14 by 180 degrees
after the proximity switches 22a and 22b are opposed to the flat portions 21c results
in the proximity switches 23a and 23b being opposed to the flat portions 21c.
[0025] The machine base control device 19 is equipped with a CPU 24, a ROM 25, a RAM 26,
an input device, and an input/output interface (not shown). The CPU 24 controls the
driving motors 15a and 15b through the inverter 18, and controls a motor (not shown)
for driving a lifting driving system and a spindle driving system (not shown), thus
functioning as the control device of the spinning machine.
[0026] The machine base control device 19 is electrically connected to the proximity switches
22a, 22b, 23a, and 23b, and output signals from the proximity switches 22a, 22b, 23a,
and 23b are input to the CPU 24. The CPU 24, which constitutes the detecting means,
makes a judgment, on the basis of a signal thereof, as to whether that roller shaft
21 of each of the line shafts 14a and 14b of the back bottom roller 14 which is situated
at the end on the side opposite to the driving side has made a relative rotation with
respect to the roller shaft 21 at the driving side end; when it is determined that
it has made a relative rotation, an abnormality signal (looseness detection signal)
is output. Further, when it outputs the above-mentioned abnormality signal, the CPU
24 performs control so as to stop the operation of the spinning machine. Thus, the
CPU 24 constitutes a control device which stops the operation of the spinning machine
when a looseness detection signal is output from the looseness detecting device of
the drafting device 11.
[0027] The ROM 25 stores program data and various items of data necessary for the execution
thereof. The program data includes various fiber materials, spinning conditions, such
as spinning yarn number count and number of twist, spindle rotating speed during normal
operation, correspondence data regarding the rotating speeds of the driving motors
for the draft driving system and the lifting driving system, a map indicating the
relationship between RPM and supply electric current amount to the driving motors
15a and 15b at various winding amounts, etc. The RAM 26 temporarily stores data input
from the input device, results of computation processing in the CPU 24, etc. The input
device is used to input spinning condition data, such as spinning yarn number count,
fiber type (material), maximum spindle RPM during spinning operation, spinning length,
lift length, chase length, and the length of the bobbin used.
[0028] Next, the operation of the device, constructed as described above, will be illustrated.
Prior to the operation of the spinning machine, the spinning conditions, such as fiber
material, spinning yarn count, and number of twist, are input to the machine base
control device 19 by the input device. When the operation of the spinning machine
is started, the driving motors 15a and the 15b are rotated and controlled through
the inverter 18 in correspondence with the spinning conditions on the basis of a command
from the machine base control device 19. Further, the driving motor for the spindle
driving system and the lifting system is also controlled such that it attains a predetermined
rotating speed.
[0029] When the spinning machine is operated, roving R runs from the back rollers of the
drafting device 11 and passes between the front rollers to be thereby drafted, and
is then taken up in a take-up portion (not shown) by a bobbin rotated integrally with
the spindle.
[0030] Further, when the spinning machine is operated, the bottom rollers 12 through 14
are rotated at a predetermined speed. Each of the roller shafts 21 corresponding to
the proximity switches 22a, 22b, 23a, and 23b has a flat portion 21c formed at one
position thereof, so that when a roller shaft 21 makes one rotation, one pulse signal
is output from the corresponding proximity switch. As shown in Fig. 3 as the normal
portion, when there is no looseness, pulse signals are alternately output from the
proximity switch 22a on the side opposite to the driving side end and the proximity
switch 23a on the driving side end.
[0031] However, when variation is generated in the load acting on the plurality of roller
shafts 21 constituting the back bottom roller 14, and a great difference in load is
generated between different roller shafts 21, relative rotation is caused between
a roller shaft 21 under large load and a roller shaft 21 under small load. For example,
when relative rotation occurs in the line shaft 14a and the screw portion is loosened,
the roller shaft 21 at the end on the side opposite to the driving side moves to the
opposing, line shaft 14b side. In the condition in which the roller shaft 21 at the
driving side end and the roller shaft 21 on the side opposite to the driving side
make relative rotation as a result of the generation of looseness in the screw portion
of the roller shafts 21, pulse signals are output from the proximity switch 23a at
the same interval as in the normal state, whereas no pulse is generated from the proximity
switch 22a or the interval of generation of pulse signals therefrom is long. Thus,
as shown in Fig. 3 as the abnormal state, a condition is attained in which pulse signals
are successively generated fromthe proximity switch 23a. When this state is attained,
the CPU 24 determines that looseness has been generated in the roller shafts 21, and
output an abnormality signal. On the basis of this abnormality signal, operation stop
control for the machine base is executed, and informing means, such as a buzzer or
an alarm lamp, is driven, and the operator is informed of the abnormality.
[0032] Similar looseness detection is performed on the other line shaft 14b. In this embodiment,
the CPU 24 performs detection on the four line shafts 14a, 14a and 14b, 14b to see
whether there is any looseness in the roller shafts 21.
[0033] The gap between the opposing surfaces of the pair of line shafts 14a and 14b constituting
the back bottom roller 14 is as small as approximately 10 mm or less. And, the roller
shaft 21 at the end on the side opposite to the driving side also moves to the loosened
side due to thermal expansion of the line shafts 14a and 14b, so that it is rather
difficult to detect the moving amount due to the looseness in the screw portion while
subtracting movement attributable to thermal expansion. However, in the arrangement
in which looseness in the roller shafts 21 is detected on the basis of rotation of
a roller shaft 21, the thermal expansion of the line shafts 14a and 14b has no influence
on the rotation, so that it is easy to accurately detect looseness in the screw portion.
[0034] This embodiment of the invention provides the following advantages:
(1) In the drafting device 11 equipped with the back bottom roller 14 divided into
the two line shafts 14a and 14b, each of the line shafts 14a and 14b being driven
from the machine base end side, there is provided detecting means which detects looseness
in the roller shafts 21 on the basis of rotation of the roller shaft 21 of the plurality
of roller shafts 21 which is situated at the end on the side opposite to the driving
side. Thus, no matter which screw portion may be loosened, it is possible to detect
looseness in the roller shafts 21 and to take appropriate measures, such as stopping
of the machine base, on the basis of the detection signal. Further, it is possible
to accurately detect looseness in the roller shafts 21 without taking into account
the expansion of the line shafts due to thermal expansion. Further, in the arrangement
in which rotation of the roller shaft 21 is detected, detection can be effected with
sufficient degree of accuracy even if the moving amount of the roller shaft 21 per
rotation of the roller shaft 21 is small.
(2) The detecting means detects the looseness on the basis of relative rotation between
the roller shaft 21 situated at the end on the side opposite to the driving side and
the roller shaft 21 situated at the driving side end. Thus, no matter which roller
shaft 21 may be loosened, both roller shafts 21 make relative rotation, and the detection
accuracy is improved as compared with the detection method which is based on relative
rotation between the roller shafts 21 provided at the ends of the two line shafts
14a and 14b whose end surface are opposed to each other.
(3) The proximity switches 22a, 22b, 23a, and 23b are used as the detecting portions
of the detecting means. Thus, the possibility of erroneous detection due to the influence
of lint is lowered as compared with the case of the detecting portion which uses as
the detecting portion an optical sensor or the like which detects any photoreception
in the photoreceptor portion or the photoreception amount.
(4) A substantially D-shaped sectional configuration is imparted to the portions of
the portion-to-be-detected side roller shaft 21, forming the flat portions 21c. Thus,
unlike the case in which the portion to be detected protrudes from the peripheral
surface of the circular portion, there is no protrusion on the outer side of the peripheral
surface of the back bottom roller 14. As a result, the portion to be detected is not
in the way when arranging the guide plate for the fiber bundle on the downstream side
of the back bottom roller 14 in close proximity thereto. Further, when fixing some
other component as the portion to be detected by means of adhesive or the like, the
durability thereof is a matter of concern. However, in the construction in which partial
cutting is effected, there is no need to worry about durability.
(5) Since the operation of the spinning machine is stopped on the basis of a detection
signal issued upon detection of looseness in the screw portion, it is possible to
prevent the operation from being continued in the abnormal state, thus preventing
damage, etc. of the components of the drafting device 11.
(6) In a spinning machine in which a pair of drafting devices 11 are provided on the
right and left sides, each drafting device 11 is equipped with the detecting means.
Thus, it is possible to achieve the advantages (1) through (5) in an ordinary ring
spinning machine, etc.
[0035] The above-described embodiment should not be construed restrictively. For example,
the following modifications are also possible.
[0036] It is also possible to omit the proximity switches 23a and 23b provided at the driving
side ends of the line shafts 14a and 14b and to detect looseness in the roller shafts
21 on the basis of rotation of the roller shafts 21 situated at the ends of the pair
of line shafts 14a and 14b on the side opposite to the driving side. The CPU 24 compares
the output pulse signals of the proximity switches 22a and 22b of the pair of line
shafts 14a and 14b, and when the output pulse signals of one of the proximity switches
are input successively, determines that looseness has been generated in the screw
portion. In the case in which the two line shafts 14a and 14b are loosened simultaneously
and in the same manner, the roller shafts 21 make no relative rotation, and it is
impossible to detect movement toward the loosened side. However, this presents substantially
no problem since the probability of the two line shafts 14a and 14b being loosened
simultaneously and in the same manner is very low. In this construction, it is possible
to reduce the number of proximity switches, thereby achieving a reduction in cost.
[0037] In a spinning machine in which a pair of drafting devices 11 are provided on the
right and left sides, instead of performing comparison on the output pulse signals
of the proximity switches 22a and 22b provided in correspondence with the pair of
line shafts 14a and 14b, it is also possible to perform comparison between the proximity
switches of the line shafts driven by the same driving motor. Further, it is also
possible to perform comparison on the output pulse signals of the four proximity switches
22a, 22b, 23a, and 23b. In the arrangement in which comparison is performed on the
output pulse signals of the four proximity switches 22a, 22b, 23a, and 23b, the probability
of all the four line shafts 14a, 14a and 14b, 14b being loosened simultaneously and
in the same manner is lower than in the case of two line shafts, so that it is assumed
that there is practically no fear of erroneous detection.
[0038] It is also possible to set the positions of the flat portions 21c such that in the
condition in which the back bottom roller 14 is rotating in the normal fashion, the
proximity switches 22a, 22b, 23a, and 23b come to face the flat portions 21c simultaneously,
that is, the pulse signals are output simultaneously from the proximity switches 22a,
22b, 23a, and 23b. Further, it is not absolutely necessary to effect phase deviation
by 180 degrees as in the above-described embodiment. The same effect can be obtained
by setting the angle arbitrarily.
[0039] The arrangement in which looseness in the screw portion is detected through comparison
of the output pulse signals of at least two proximity switches should not be construed
restrictively. It is also possible to adopt an arrangement in which it is determined
that looseness has been generated when the rotation speed of the roller shaft 21 as
computed from the output pulse generation interval of the proximity switch 22a for
detecting rotation of the roller shaft 21 situated at the end on the side opposite
to the driving side is different from the rotation speed thereof as computed from
the rotation speed of the driving motors 15a and 15b.
[0040] It is also possible to provide a plurality of (e.g., two) flat portions 21c. In this
case, two pulses are output through one rotation of the roller shaft 21, so that detection
is possible at a stage where the looseness generated is less than in the case of one
flat portion. However, one flat portion suffices.
[0041] Instead of forming the flat portion 21c as the portion to be detected on the roller
shaft 21 by machining, it is also possible to fix an iron piece or a magnet to the
outer periphery of the roller shaft 21.
[0042] The detecting portions (sensors) constituting the detecting means are not restricted
to the proximity switches. It is also possible to use sensors, such as magnetic sensors
or optical sensors.
[0043] It is also possible to adopt an arrangement other than the one in which, on the basis
of detection signals from the sensors, the CPU 24 of the machine base control device
19 detects looseness in the roller shafts 21 on the basis of rotation of the roller
shaft 21 situated at the end on the side opposite to the driving side. For example,
when the proximity switches 22a, 22b, 23a, and 23b are in the normal state, the pulse
signals may be output simultaneously from them, each output signal being input to
an AND circuit. In this arrangement, in the normal state, H-level signals are input
to the AND circuit with the same timing, so that the output is at the H-level in the
while. When looseness is generated, H-level signals are not simultaneously input to
the AND circuit, and its output is at the L-level. Thus, when the output of the AND
circuit does not attain H-level within a predetermined period of time, it is to be
determined that looseness has been generated in the screw portion.
[0044] Instead of detecting looseness in the roller shafts 21 on the basis of rotation of
the roller shaft 21 situated at the end on the side opposite to the driving side,
it is also possible to adopt an arrangement in which there is detected axial movement
in the loosened side (opposite to the driving side) of the roller shaft 21 situated
at the end on the side opposite to the driving side by an amount not less than a predetermined
amount. An amount not less than a predetermined amount refers to an amount larger
than the expansion due to thermal expansion.
[0045] Instead of the construction in which the line shafts 12a, 13a, and 14a are driven
by the driving motor 15a and in which the line shafts 12b, 13b, and 14b are driven
by the driving motor 15b, it is also possible to adopt a construction in which the
line shafts 12a, 13a and the line shafts 12b, 13b of the front bottom roller 12 and
the middle bottom roller 13 are respectively driven by driving motors different from
the driving motors 15a and 15b. In this case, changing of the drafting ratio is facilitated.
[0046] The drafting device 11 is not restricted to the three-line type; it may also be a
device having four or more drafting rollers on one side.
[0047] The present invention is applicable not only to a ring spinning machine equipped
with the drafting device 11 on either side but also to a ring spinning machine performing
spinning on one side only, for example, a ring spinning machine which directly spins
fine spinning thread by drafting sliver skipping the stage of roving R.
1. A device for detecting looseness in drafting rollers of a spinning machine equipped
with a drafting device (11) which is equipped with a plurality of bottom rollers (12,
13, 14) consisting of a plurality of roller shafts (21) connected to each other through
threaded engagement of screw portions formed at the ends thereof, each bottom roller
(12, 13, 14) being divided into two line shafts (12a, 12b, 13a, 13b, 14a, 14b) and
arranged coaxially, each line shaft (12a, 12b, 13a, 13b, 14a, 14b) being driven from
the end side of a machine base,
characterized in that the detecting device comprises detecting means (22a, 22b, 24) for detecting looseness
in the roller shafts on the basis of rotation or axial movement of that roller shaft
(21) of the plurality of roller shafts (21) constituting the back bottom roller (14)
which is situated at the end on the side opposite to the driving side.
2. A device for detecting looseness in drafting rollers of a spinning machine according
to Claim 1, characterized in that the detecting means (22a, 22b, 24) detects the looseness on the basis of rotation
of the roller shaft (21) situated at the end on the side opposite to the driving side.
3. A device for detecting looseness in drafting rollers of a spinning machine according
to Claim 2, characterized in that the detecting means (22a, 22b, 23a, 23b, 24) detects the looseness on the basis of
relative rotation between the roller shaft (21) situated at the end on the side opposite
to the driving side and the roller shaft (21) situated at the driving side end.
4. A device for detecting looseness in drafting rollers of a spinning machine according
to Claim 2, characterized in that the detecting means (22a, 22b, 24) detects the looseness on the basis of relative
rotation between opposing roller shafts (21) situated at the end on the side opposite
to the driving side.
5. A device for detecting looseness in drafting rollers of a spinning machine according
to any one of Claims 1 through 4, characterized in that, in a spinning machine having a pair of the drafting devices (11) on right and left
sides, the detecting means (22a, 22b, 23a, 23b, 24) is provided in each drafting device(11).
6. A device for detecting looseness in drafting rollers of a spinning machine according
to Claim 2, characterized in that, in a spinning machine having a pair of the drafting devices (11) on right and left
sides, the detecting means (22a, 22b, 23a, 23b, 24) is provided in each drafting device,
and that the detecting means detects the looseness on the basis of rotation of four
roller shafts (21) situated at the ends on the side opposite to the driving side.
7. A device for detecting looseness in drafting rollers of a spinning machine according
to any one of Claims 2 through 6, characterized in that the detecting means includes a proximity switch (22a, 22b, 23a, 23b) as a detecting
portion, and that the roller shaft (21) on the portion-to-be-detected side has at
least one recess at a position corresponding to the proximity switch (22a, 22b, 23a,
23b) where its section is recessed relative to its section around the recess.
8. A device for detecting looseness in drafting rollers of a spinning machine according
to any one of Claims 2 through 7, characterized in that the detecting means is equipped with a proximity switch (22a, 22b, 23a, 23b) as a
detecting portion, and that the roller shaft (21) on the portion-to-be-detected side
has at a position corresponding to the proximity switch (22a, 22b, 23a, 23b) a substantially
D-shaped section.