U.S. patent application number 11/726166 was filed with the patent office on 2007-09-27 for oscillating control device for linear knitting machines thread-guide bars.
This patent application is currently assigned to SANTONI S.P.A.. Invention is credited to Tiberio Lonati.
Application Number | 20070220925 11/726166 |
Document ID | / |
Family ID | 38222332 |
Filed Date | 2007-09-27 |
United States Patent
Application |
20070220925 |
Kind Code |
A1 |
Lonati; Tiberio |
September 27, 2007 |
OSCILLATING CONTROL DEVICE FOR LINEAR KNITTING MACHINES
THREAD-GUIDE BARS
Abstract
An oscillating control device (1) for thread-guide bars (2) of
linear knitting machines (60), comprising a support (5) that can
rotate around a middle axis (6) to which at least one thread-guide
bar (2) can be associated, movement means (10) for the support (5),
and transmission means (20) operatively connected to the movement
means (10) for imparting an oscillating movement to the support
(5). The transmission means (20) are operatively associated to the
support (5) on at least two separate actuating points (7a, 7b) for
moving it with an oscillating movement in a balanced manner with
respect to the middle axis (6) thereof. In particular, a pushing
action and a pulling action are applied simultaneously on the two
actuating points (7a, 7b) by the movement means (10) through the
transmission means (20).
Inventors: |
Lonati; Tiberio; (Brescia,
IT) |
Correspondence
Address: |
PEARNE & GORDON LLP
1801 EAST 9TH STREET, SUITE 1200
CLEVELAND
OH
44114-3108
US
|
Assignee: |
SANTONI S.P.A.
|
Family ID: |
38222332 |
Appl. No.: |
11/726166 |
Filed: |
March 21, 2007 |
Current U.S.
Class: |
66/204 |
Current CPC
Class: |
D04B 27/24 20130101;
D04B 27/08 20130101; D04B 27/26 20130101 |
Class at
Publication: |
66/204 |
International
Class: |
D04B 23/00 20060101
D04B023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 23, 2006 |
IT |
BS2006A000066 |
Claims
1. An oscillating control device (1) for thread-guide bars (2) of
warp linear knitting machines (60), comprising: a support (5) that
can rotate around a central axis (6) to which at least one
thread-guide bar (2) can be associated, movement means (10) for
said support (5), and transmission means (20) operatively connected
to the movement means (10) for imparting an oscillating movement to
said support (5); characterized in that said transmission means
(20) are operatively associated to said support (5) on at least two
separate actuating points (7a, 7b) for moving said support (5)
according to said oscillating movement in a balanced manner with
respect to said central axis (6).
2. The device (1) according to claim 1, characterized in that said
actuating points (7a, 7b) are opposed with respect to a vertical
plane containing said central axis (6).
3. The device (1) according to claim 1, characterized in that a
pushing action and a pulling action are applied simultaneously on
said two actuating points (7a, 7b) by said movement means (10)
through said transmission means (20).
4. The device (1) according to claim 1, characterized in that said
transmission means (20) comprise main transmission means (21)
operatively connected to said movement means (10), and secondary
transmission means (25) operatively associated to said main
transmission means (21) and moved by said main transmission means
(21), said main transmission means (21) acting upon said support
(5) at a first (7a) of said actuating points and said secondary
transmission means (25) acting upon said support (5) on a second
(7a) of said actuating points.
5. The device (1) according to claim 4, characterized in that said
main and secondary transmission means (21, 25) exert simultaneously
onto said support (5), by means of the corresponding actuating
points (7a, 7b), said pushing action said the pulling action,
respectively, or vice versa.
6. The device (1) according to claim 4, characterized in that said
transmission means (20) further comprise connection means (30)
between said main transmission means (21) and said secondary
transmission means (25), designed to transmit synchronously to said
secondary transmission means (25) the movement supplied by said
movement means (10) through said main transmission means (21).
7. The device (1) according to claim 4, characterized in that said
main transmission means (21) comprise a main shaft (22) operatively
connected to said movement means (10), and a main connecting rod
(23) operatively associated to said main shaft (22) and to said
support (5) on said first actuating point (7a).
8. The device (1) according to claim 7, characterized in that said
main transmission means (21) further comprise a main eccentric pin
(24) associated to a portion of said main shaft (22), said main
connecting rod (23) being associated to said main shaft (22) by
means of said main eccentric pin (24).
9. The device (1) according to claim 7, characterized in that said
secondary transmission means (25) comprise a secondary shaft (26)
operatively associated to said connection means (30), and a
secondary connecting rod (27) operatively associated to said
secondary shaft (26) and to said support (5) on said second
actuating point (7b) and designed to cooperate with said main
connecting rod (23) for moving said support (5) according to said
oscillating movement.
10. The device (1) according to claim 9, characterized in that said
oscillating movement imparted by said main connecting rod (23) and
by said secondary connecting rod (27) to said support (5) is
sinusoidal.
11. The device (1) according to claim 9, characterized in that said
secondary transmission means (25) further comprise a secondary
eccentric pin (28) associated to a portion of said secondary shaft
(26), said secondary connecting rod (27) being associated to said
secondary shaft (26) by means of said secondary eccentric pin
(28).
12. The device (1) according to claim 9, characterized in that said
connection means (30) comprise a main pulley (31) integrally
associated to said main shaft (22), a secondary pulley (32)
integrally associated to said secondary shaft (26), and a
connection belt (33) associated to the said main pulley (31) and to
said secondary pulley (32) for transmitting the movement of said
main pulley (31) to the secondary shaft (26) by means of said
secondary pulley (32).
13. The device (1) according to claim 1, characterized in that it
further comprises at least one secondary support (8) to which one
of said thread-guide bars (2) can be associated, said at least one
secondary support (8) being associated to said support (5).
14. The device (1) according to claim 7, characterized in that said
movement means (10) comprise at least one dedicated motor (11).
15. The device (1) according to claim 14, characterized in that
said main shaft (22) is connected integrally to said dedicated
motor (10), and in that said main connecting rod (23) is designed
to convert a rotational motion of said main shaft (22) generated by
said dedicated motor (11) into said oscillating movement for said
support (5).
16. The device (1) according to claim 14, characterized in that
said dedicated motor (11) is a brushless motor.
17. The device (1) according to claim 1, characterized in that said
movement means (10) can be operatively associated to a central
motor (13) of said machine (60), designed to move the needles of
said machine (60).
18. The device (1) according to claim 17, characterized in that
said movement means (10) comprise a first movement pulley (14)
operatively associated to said main shaft (22), a second movement
pulley (15) that can be operatively associated to said central
motor (13), and a movement belt (16) operatively connected to said
first (14) and to said second (15) movement pulley for transmitting
to said first movement pulley (14) the movement of said second
movement pulley (15).
19. The device (1) according to claim 17, characterized in that
said movement means (10) further comprise first means (17) for
varying the rotational speed of said main shaft (22) with respect
to the rotational speed of said central motor (13) associated to
said movement belt (16).
20. A warp linear knitting machine (60) characterized in that it
comprises at least one oscillating control device (1) for
thread-guide bars (2) according to claim 1.
21. The machine (60) according to claim 20, characterized in that
it comprises at least two of said devices (1), one of said devices
(1) being positioned on a first end portion (3) of said at least
one thread-guide bar (2) and one being positioned on a second end
portion (4) opposite said first end portion (3), so as to prevent
torsions of said at least one thread-guide bar (2).
22. The machine (60) according to claim 21, characterized in that
it further comprises at least one intermediate support (9)
associated to said at least one thread-guide bar (2) on an
intermediate portion (2a) thereof located between said first (3)
and said second (4) end portion, for supporting said at least one
thread-guide bar (2), said intermediate support (9) being movable
according to said oscillating movement around said second middle
axis (6).
23. The machine (60) according to claim 20, characterized in that
it further comprises control means (40) designed to ensure the
synchronism between said oscillating movement of said supports (5)
of said devices (1) and to ensure the continuity of movement for
said at least one thread-guide bar (2) in case of failures.
24. The machine (60) according to claim 23, characterized in that
said control means (40) comprise an auxiliary shaft (41)
operatively associated to said secondary shafts (26) of said two
devices (1) associated to said at least one thread-guide bar (2),
designed to stiffly connect said secondary shafts (26).
25. The machine (60) according to claim 20, characterized in that
it further comprises coordination means (50) between said central
motor (13) and said dedicated motors (11), designed to adapt the
movement of said dedicated motors (11) to the movement of said
central motor (13) for synchronizing the movement of said at least
one thread-guide bar (2) to the movement of the needles.
26. The machine (60) according to claim 25, characterized in that
said coordination means (50) comprise a first detection element
(51) associated to said central motor (13) and designed to detect
the angular position of said central motor (13), at least one
second detection element (52), said at least one second detection
element (52) being associated to each of said dedicated motors (11)
for detecting the angular position of said dedicated motors (11),
and an electronic adjustment element designed to process signals
transmitted by said first (51) and by said second (52) detection
element for synchronizing said dedicated motors (11) with said
central motor (13).
27. The machine (60) according to claim 26, characterized in that
said first (51) and said second (52) detection element comprise
transducers of angular position.
28. The machine (60) according to claim 25, characterized in that
said coordination means (50) further comprise at least one first
coordination pulley (53), associated to each of said dedicated
motors (11), a second coordination pulley (54) associated to said
central motor (13), and a coordination belt (55) operatively
connected to said first (53) and to said second (54) coordination
pulley so as to move said first coordination pulley (53) according
to the movement of said second coordination pulley (54).
29. The machine (60) according to claim 28, characterized in that
said coordination means (50) further comprise second means (56) for
varying the rotational speed of said first coordination pulley (53)
with respect to said second coordination pulley (54).
30. The machine (60) according to claim 28, characterized in that
said dedicated motor (11) has two shafts, the first one made up of
said main shaft (22) and the second one made up of a coordination
shaft (57) operatively connected to said first coordination pulley
(53).
31. The machine (60) according to claim 20, characterized in that
said central motor (13) has two shafts made up of movement shafts
(12) operatively connected to said second movement pulleys (15) for
the two devices (1), associated to said first (3) and to said
second (4) end portion of said at least one thread-guide bar (2),
respectively.
Description
[0001] The present invention relates to an oscillating control
device for thread-guide bars of linear knitting machines, also
known as Raschel-type warp looms, tricot, crochet or the like.
[0002] As is known, Raschel-type linear knitting machines are
provided with a plurality of bars designed to carry a plurality of
thread-holding elements, commonly known as thread-guides. Said bars
should be moved so as to enable the threads associated to the
thread-guides to be correctly fed onto the needles of the knitting
machine for the formation of new fabric with the well-known
technique in which the new thread enters the old loop and the old
loop is discharged and becomes part of the fabric being formed. In
order to achieve its knitting task, the thread-guide bar makes two
basic movements simultaneously, i.e. a first linear movement in
front of the hook of each needle, commonly known as "shog", and an
oscillating movement on the side of each needle for bringing the
threads alternatively before and behind the needle hook, commonly
known as "swing".
[0003] The present invention relates to a device for enabling the
oscillating movement ("swing") for the thread-guides.
[0004] Currently, in linear knitting machines the oscillation of
the thread-guide bars, which is usually of 4.degree. to 10.degree.,
is obtained by means of several methods, all of which exploit
leverage systems, such as quadrilaterals, suitably connected to one
another and derived from systems for handling the rising and
descent of needles for the formation of the knitted stitch, as is
shown for instance in documents WO 03/071018 and U.S. Pat. No.
3,221,520. Accordingly, the whole mechanism of the machine is
rigorously synchronized in its basic movements, whatever the speed
at which the machine is running.
[0005] As is known, thread-guide bars, eight of them being
generally present on double needle-bed machines, are associated to
at least one support, which is in its turn connected to said
leverage systems for transmitting the oscillating movement thereof.
Said bars are connected to two supports, each of them being placed
on one of the end portions thereof. If necessary, it can further be
provided for intermediate resting supports, which can both actively
transmit the oscillating movement and be passively subjected to
it.
[0006] As was already said, the leverages convert the linear
movement resulting from the needles into an oscillating movement
for the thread-guide bars. As a matter of fact, the oscillating
movement is generated by the movement of a rod connected to the
support of the thread-guide bars so as to make it rotate around the
axis of the shaft supporting it. As a rule, as can be seen in FIG.
1, the support of the thread-guide bar is made up of a main body to
which the bars as connected, and of a supporting arm, upon which
the rod acts and which has a main axis basically perpendicular to
the main axis of the main body. Moreover, the support is associated
to the shaft supporting it on the point of connection between the
arm and the main body, which is also the center of rotation for
said support. This particular structure allows to obtain an
oscillating movement for the main body starting from the linear
movement of the arm obtained by means of the rod.
[0007] Known devices as disclosed above show various drawbacks.
Firstly, the systems for transmitting motion from the motor of the
machine to the thread-guide bars are quite complex, since they have
to be extremely accurate because of the narrow spaces in which
needles and thread-guides work with respect to the overall size of
the machines, and require a very large number of components. This
increases costs hugely. Moreover, the mechanical complexity of the
devices strongly limits their speeds of use, and thus said machines
often represent a bottleneck in the manufacturing system into which
they are integrated.
[0008] Secondly, said devices have a very low flexibility, since it
is very difficult to make after-changes to them because of their
complexity. Even maintenance operation for repairing or replacing
elements can be complex. Anyhow, these operations require the
intervention of specialized personnel working for the company that
has made the machines, with subsequent problems of production stops
and further cost increase.
[0009] Eventually, another problem with known systems consists in
the need to continuously invert the direction of movement of the
support, and thus of the thread-guide bars, so as to make
oscillations. As a matter of fact, the masses involved, which are
quite high, have to be pushed in one direction, so as to create a
counterclockwise oscillation for instance, then at stroke end they
have to be braked and pushed in the opposite direction, so as to
make the following clockwise oscillation for instance. Such a
device, therefore, gives rise to several mechanical problems
leading inevitably to solutions involving large overall sizes of
stressed components and strong reductions of operating speeds.
Moreover, said devices generate very strong vibrations that have to
be absorbed by the machine through suitable measures, such as for
instance big anti-vibration supporting structures.
[0010] The state of the art shows devices mitigating the problem
disclosed above, though further increasing costs. They are
basically made up of eccentric systems based on the principle of
connecting rod-crank imparting a sinusoidal movement to the
support, as shown in FIG. 2. The sinusoidal movement of the
connecting rod slows down the stroke of the support on the point of
inversion of the movement, thus greatly reducing vibrations and
discharging the forces of inertia generated on the various
mechanical connections as far as the motor.
[0011] Moreover, known knitting machines can include even more than
two of the conventional devices associated to the ends of the
thread-guide bars. For instance, in a machine with a needle-bed
having a length of about 3.5 m, there can be 8 devices spaced from
one another of about 0.5 m. As a matter of fact, the use of several
devices enables to reduce size and, therefore, to obtain higher
speeds of use. However, in this case the size of the motor and of
the shaft connected thereto significantly increases, since eight of
these devices are fitted onto the shaft, together with other
devices involved in the movement of needles and other elements,
which devices increase the forces of inertia involved due to the
masses in movement that have to be moved in a suitable manner both
at constant speed and during acceleration or braking.
[0012] It should be pointed out that, generally, these devices are
located in the portion containing the rear needle-bed, thus leaving
the front portion of the machine free for different reasons, also
of economical nature. Therefore, the system is not balanced and
gives rise to vibrations occurring also at low speeds (350
oscillations per minute for instance).
[0013] The aim of the present invention is to solve the problems at
the state of the art by proposing an oscillating control device for
thread-guide bars of linear knitting machines without the drawbacks
described above. Therefore, an aim of the present invention is to
propose an oscillating control device for thread-guide bars of
linear knitting machines that enables to reduce the manufacturing
and management costs of the knitting machines. As a consequence, an
aim of the invention is to provide an oscillating control device
for thread-guide bars of linear knitting machines that has a small
number of components and enables to simplify the structure of the
machine and the construction and management thereof, especially as
far as maintenance is concerned.
[0014] A further aim of the invention is to show an oscillating
control device for thread-guide bars of linear knitting machines
that is very accurate and ensures a high quality of the finished
item.
[0015] Still another aim of the present invention is to increase
the operating speed of the knitting machine so that the knitting
station represents no more a bottleneck in the whole manufacturing
process of knitted items.
[0016] Moreover, an aim of the invention is to show an oscillating
control device for thread-guide bars of linear knitting machines
that generates on the supports, and therefore on the thread-guide
bars, a controlled and balanced oscillating movement especially in
the critical steps of acceleration, braking and movement inversion,
so that a strong over-sizing of the structural components of the
machine is not required and the generation of vibrations and shakes
is reduced.
[0017] A final aim of the invention is to show an oscillating
control device for thread-guide bars of linear knitting machines
that enables to balance the forces acting upon the machine, so that
the knitting machine has a compact, rational and dynamically
balanced structure.
[0018] These and other aims that will emerge from the following
description are achieved, according to the present invention, by an
oscillating control device for thread-guide bars of linear knitting
machines in accordance with the appended claims.
[0019] The invention will now be disclosed in further detail thanks
to the drawings, which represent a merely exemplary and
non-limiting embodiment thereof.
[0020] FIGS. 1 and 2 show examples of known oscillating control
devices for thread-guide bars of linear knitting machines;
[0021] FIG. 3 shows a side view of an oscillating control device
for thread-guide bars of linear knitting machines in accordance
with the invention;
[0022] FIG. 4 shows a first schematic front view of a knitting
machine according to the invention in a first embodiment
thereof;
[0023] FIG. 5 shows a schematic front view of a detail of the
machine according to the invention;
[0024] FIG. 6 shows a top view of the machine according to the
invention in the first embodiment thereof;
[0025] FIG. 7 shows a perspective view of the device of FIG. 3
associated to a first end portion of the thread-guide bars;
[0026] FIG. 8 shows a perspective view of the device of FIG. 3
associated to a second end portion of the thread-guide bars;
[0027] FIG. 9 shows a second schematic front view of the machine of
FIG. 4;
[0028] FIG. 10 shows a schematic side view of the machine according
to the invention in a second embodiment thereof.
[0029] With reference to the figures mentioned above, an
oscillating control device 1 for thread-guide bars 2 of linear
knitting machines 60 according to the present invention comprises a
support 5 that can rotate around a middle axis 6 to which at least
one thread-guide bar 2 can be associated, movement means 10 for the
support 5, and transmission means 20 operatively connected to the
movement means 10 for imparting an oscillating movement to the
support 5.
[0030] The device 1 is characterized in that the transmission means
20 are operatively associated to the support 5 on at least two
separate actuating points 7a, 7b for moving it with an oscillating
movement in a balanced manner with respect to the middle axis 6
thereof.
[0031] As can be seen in FIG. 3, said points 7a, 7b for actuating
the support 5 are opposed with respect to a vertical plane
containing the middle axis 6. Moreover, a pushing action and a
pulling action are applied simultaneously on the two actuating
points 7a, 7b, respectively, by the movement means 10 through the
transmission means 20. In further detail, every time the support 5
moves with an oscillating movement, a pushing action is applied on
one of two actuating points 7a, 7b and a pulling action is applied
on the other one. As a consequence, these devices 1 can also be
defined "push-pull" devices.
[0032] It is thus possible to balance the forces acting upon the
device 1 and to control their dynamics effectively. Moreover, the
oscillating movement of the support 5 takes place in a plane
basically perpendicular to the longitudinal development of the
thread-guide bars 2, so that the middle axis 6 of said support 5 is
basically parallel to the main axes of the thread-guide bars 2. The
transmission means 20 comprise main transmission means 21
operatively connected to the movement means 10, and secondary
transmission means 25 operatively connected to the main
transmission means 21 and moved by the latter. The main
transmission means 21 act upon the support 5 on a first actuating
point 7a, whereas the secondary transmission means 25 act upon it
on a second actuating point 7b (FIGS. 3 and 6).
[0033] Advantageously, therefore, the main and secondary
transmission means 21, 25 exert onto the support 5, by means of the
corresponding actuating points 7a, 7b, the pushing action and the
pulling action, respectively, for oscillations in one direction and
vice versa for oscillations in the other direction.
[0034] The transmission means 20 further comprise connection means
30 between the main transmission means 21 and the secondary
transmission means 25, so as to transmit synchronously to the
secondary transmission means 25 the movement supplied by the
movement means 10 through the main transmission means 21 (FIGS. 3
and 6).
[0035] According to the invention, the main transmission means 21
comprise a main shaft 22 operatively connected to the movement
means 10, and a main connecting rod 23 operatively associated to
the main shaft 22 and to the support 5 on the first actuating point
7a. A further component of said means 21 is a main eccentric pin 24
associated to a portion of the main shaft 22, preferably to an end
portion thereof, so that the main connecting rod 23 is fitted onto
the main shaft 22 by means of said main eccentric pin 24 (FIG.
4).
[0036] In their turn, the secondary transmission means 25 comprise
a secondary shaft 26 operatively associated to the connection means
30, and a secondary connecting rod 27 operatively associated to
said secondary shaft 26 and to the support 5 on the second
actuating point 7b.
[0037] Preferably, the secondary transmission means 25 also
comprise a secondary eccentric pin 28 associated to a portion, as a
rule an end portion, of the secondary shaft 26. Here again, the
connecting rod 27 is fitted onto the secondary shaft 26 by means of
said secondary eccentric pin 28.
[0038] The secondary connecting rod 27 is designed to cooperate
with the main connecting rod 23 for moving the support 5 with an
oscillating movement.
[0039] The two shafts, the main one 22 and the secondary one 26,
rotate synchronously, whereas their connecting rods 23, 27 operate
with phase opposition due to the different location of the
eccentric pin 24, 28 of the respective shafts 22, 26. Therefore,
while one of them, the main connecting rod 23 for instance, pushes
the support 5 and makes it rotate with respect to its middle axis 6
counterclockwise, the other one, the secondary one 27 for instance,
pulls simultaneously the support 5 cooperating with the main
connecting rod 23 so that said support rotates counterclockwise in
a balanced manner.
[0040] Advantageously, the oscillating movement imparted by the
main connecting rod 23 and by the secondary connecting rod 27 to
the support is sinusoidal and dampened at its ends, i.e. during
movement inversion. This allows to maximize the effectiveness of
the movement since, both during acceleration and during braking,
the two connecting rods 23, 27 cooperate to the movement by sharing
in a fair manner the efforts and the absorptions of the forces of
inertia generated at high oscillating speeds. Thus, this results in
a harmonious movement without all negative components generated in
known devices 1 moved with means operating only on one side, i.e.
with only one connecting rod.
[0041] The connection means 30 comprise a main pulley 31 integrally
associated to the main shaft 22, a secondary pulley 32 integrally
associated to the secondary shaft 26, and a connection belt 33
associated to the two pulleys 31 and 32 for transmitting the
movement of the main pulley 31 to the secondary shaft 26 exactly by
means of the secondary pulley 32. Generally, in double needle-bed
linear knitting machines 60, every support 5 is associated to
approximately eight thread-guide bars 2. Preferably, the bars 2 are
not associated to the support 5 directly but by means of secondary
supports 8, to which only one bar 2 can be associated and which are
integral with the support 5, as shown in FIGS. 3, 4, 5, 7 and 8. It
should be pointed out that every secondary support 8 is integral
with the support 5 as far as rotation is concerned, while it can
move with translational motion with respect to the support 5 so as
to enable the translation of the bars 2 as required for the
movement of said bars 2 commonly known as "shog".
[0042] In a first execution variant shown in detail in Figures 4, 6
and 9, which is also the preferred embodiment of the invention, the
movement means 10 comprise at least one dedicated motor 11. This
dedicated motor .mu.l is designed only to move the support 5 and is
different from the central motor 13 moving the other elements of
the machine 60 such as the needles.
[0043] In this case, therefore, the main shaft 22 is integrally
connected to the dedicated motor 11, and the main connecting rod 23
is designed to convert the rotational motion of the main shaft 22
generated by the dedicated motor 11 into an oscillating motion for
the support 5.
[0044] Preferably, the dedicated motor 11 is a brushless motor, but
other types suitable to this purpose can be used, such as stepper
motors or direct current motors. As an alternative, two dedicated
motors 11 synchronized with one another can be used, so as to move
the main 21 and the secondary 25 transmission means, thus without
the need for connection means 30 whose function is to move the
secondary transmission means 25 starting from the movement of the
main ones 21. Said solution, however, would be highly complex to be
carried out and managed, especially due to the need for a perfect
synchronization between the two dedicated motors 11, and would
significantly increase costs.
[0045] In a second execution variant of the invention shown in FIG.
10, the movement means 10 can be operatively associated to the
central motor 13 of the machine 60. It should be pointed out that
central motor 13 denotes the motor designed to move all the
elements of the machine 60 and in particular the needles. In this
case, therefore, the movement means 10 comprise a first movement
pulley 14 operatively associated to the main shaft 22, a second
movement pulley 15 that can be operatively associated to the
central motor 13, and a movement belt 16 operatively connected to
the first 14 and to the second 15 movement pulley for transmitting
to the first movement pulley 14 the movement of the second movement
pulley 15.
[0046] Advantageously, the movement means 10 can further comprise
first means 17 for varying the rotational speed of the main shaft
22 with respect to the rotational speed of the central motor 13,
associated to the movement belt 16. In further detail, said means
17 consist of reduction gears and are required when the main shaft
22 has to be moved at another angular speed than the one of the
central motor 13 to which it is connected and from which it
receives the movement, as typically occurs in double needle-bed
linear knitting machines 60.
[0047] The inventive idea underlying the present invention extends
also to a linear knitting machine 60 characterized in that it
comprises at least one oscillating control device 1 for
thread-guide bars 2 in accordance with the above description.
[0048] In particular, a linear knitting machine 60 in accordance
with the invention generally comprises at least two oscillating
control devices 1 for thread-guide bars 2. Preferably, one of these
devices 1 is located on a first end portion 3 of the thread-guide
bars 2, and another one is located on a second end portion 4,
opposite the first one 3, so as to prevent torsions of said
thread-guide bar 2 during oscillations.
[0049] The machine 60 can further comprise at least one
intermediate support 9 associated to the thread-guide bars 2 on an
intermediate portion 2a thereof, located between the two end
portions 3, 4, so as to support the latter (FIG. 5). Every
intermediate support 9 can move with an oscillating movement around
the central axis. Preferably, the intermediate supports 9 do not
transmit to the thread-guide bars 2 the oscillating motion but only
accompany the oscillations thereof by passively absorbing them. In
some cases, however, the intermediate supports 9 can also actively
transmit the oscillating movement to the bars 2 (which alternative
is not shown).
[0050] Advantageously, every support 5 and every intermediate
support 9 are turnably associated to an oscillating shaft 18 whose
main axis coincides with the central axis 6 around which said
supports 5 rotate. Advantageously, the thread-guide bars 2 can be
associated to every intermediate support, which houses all
thread-guide bars 2, by means of a secondary intermediate support,
as can be seen in FIG. 5.
[0051] The knitting machine 60 further comprises control means 40
designed to ensure the synchronism between the oscillating movement
of the supports 5 of the two devices 1 associated to the end
portions 3, 4 of the thread-guide bars 2, and to ensure the
continuity of movement for the thread-guide bars 2 in case of
failures. Said control means 40 comprise an auxiliary shaft 41
operatively associated to the secondary shafts 26 of the two
devices 1, so as to stiffly connect said secondary shafts 26 (FIGS.
5 and 6).
[0052] The auxiliary shaft 41 has several functions beyond the one
of ensuring the perfect synchronism between the two secondary
shafts 26 as mentioned above. As a matter of fact, the auxiliary
shaft 41 enables to ensure the continuity of movement in case some
components break, such as a connection belt 33 between the main
transmission means 21 and the secondary ones 25 of one of the two
devices 1, since the auxiliary shaft 41 can move the secondary
shaft 26 of the damaged device 1 by exploiting the movement of the
secondary shaft 26 of the undamaged device 1. The same applies to a
breakage or malfunctioning of the movement means 10, especially of
the dedicated motor 11 in the first execution variant of the
devices 1. However, the machine 60 is equipped with suitable
sensors that are able to signal the emergency condition and to stop
said machine 60 with suitable procedures.
[0053] Moreover, the auxiliary shaft 41 is adequately supported and
perfectly able to rotate on its axis 42 at high speeds without
causing unwanted vibrations in the transmission means.
[0054] A linear knitting machine 60 with oscillating control
devices 1 for thread-guide bars 2 according to the first execution
variant also comprises coordination means 50 between the central
motor 13 and the dedicated motors 11 for adapting the movement of
the dedicated motors 11 to the movement of the central motor 13 so
as to synchronize the movement of the thread-guide bars 2 to the
one of the needles. This function is highly important since the
movements of the thread-guide bars 2 and of the needles have to be
extremely stiff and coordinated so that all the needles are always
correctly fed, thus preventing damages to the finished product or
breakage of threads or needles.
[0055] Said coordination means 50 can be either electronic or
mechanical.
[0056] In the first case, the coordination means 50 comprise at
least one first detection element 51 associated to the central
motor 13, designed to detect the angular position thereof, at least
one second detection element 52 for each of the dedicated motors
11, designed to detect the angular position thereof, and an
electronic adjustment element (not shown) designed to process the
signals transmitted by the first 51 and by the second 52 detection
elements so as to synchronize the dedicated motors 11 with the
central motor 13 (FIGS. 4 and 9). For instance, the electronic
adjustment element can be an electronic card connected to the
electronic means running and managing the whole machine 60.
Moreover, the first 51 and the second 52 detection elements can
comprise position transducers of "encoder" or "resolver" type or of
other type, which are able to indicate the exact angular position
of the shaft moving with respect to a reference zero. In
particular, the signal referring to the central motor 13 is
commonly managed as main signal ("master signal") with which all
the other movements of the machine 60 have to comply.
[0057] This allows to eliminate cams, back gears, leverages, rods,
etc. which are required to connect stiffly and synchronously
elements spaced apart even of some meters and which were difficult
and expensive to be carried out. Despite being of electronic type,
the coordination means 50 of this type are able to connect stiffly
the central motor 13 to the dedicated ones 11, as if there were
actually a stiff mechanical connection between them.
[0058] The rapidity of data transmission and execution makes the
movement between the central motor 13 and the dedicated motors 11
harmoniously connected and rigorously controlled, since the
coordination means 50 can follow in real time speed variations of
the central motor 13 and adapt the mechanisms thereof under their
control, in this case the dedicated motors 11.
[0059] As was already mentioned, the coordination between the
central motor 13 and the dedicated motors 11 can also take place
with mechanical coordination means 50 making use of conventional
transmission. In this case, the coordination means 50 comprise at
least one first coordination pulley 53, each of them being
associated to each of the dedicated motors 11, a second
coordination pulley 54 associated to the central motor 13, and a
coordination belt 55 operatively connected to the first 53 and to
the second 54 coordination pulley so as to move the first
coordination pulley 53 according to the movement of the second one
54. The coordination means 50 can further comprise second means 56
for varying the rotational speed of the first coordination pulley
53 with respect to the second one 54, generally made up of
reduction gears.
[0060] Moreover, in this case every dedicated motor 11 comprises
two shafts, a first shaft made up of the main shaft 22, and a
second shaft made up of a coordination shaft 57 operatively
connected to the first coordination pulley 53.
[0061] This type of coordination means 50, which is perfectly
functional, can introduce some delays due to the imperfect
stiffness of the coordination belts 55, which delays are mitigated
by reducing the operating speed of the machine 60.
[0062] The two types of coordination means 50 can also be used
simultaneously so as to minimize the possible lack of
synchronization between the central motor 13 and the dedicated
motors 11 in case of breakages or failures of the various
components.
[0063] In the solution of embodiment in which a linear knitting
machine 60 comprises oscillating control devices 1 for thread-guide
bars 2 according to the second execution variant, the central motor
13 has two shafts. As a matter of fact, said motor 13 has two
shafts made up of the movement shafts 12 operatively connected to
the second movement pulleys 15 of the two devices 1 associated to
the first 3 and to the second 4 end portion of the thread-guide
bars 2, respectively.
[0064] It should be pointed out that, preferably, all the belts and
pulleys are toothed. However, the terms belt and pulley are to be
construed as general terms representing any transmission element
designed to perform the functions required by a knitting machine 60
in accordance with the inventive idea as described.
[0065] The invention thus conceived can undergo several changes and
variants, all of which fall within the framework of the inventive
idea.
[0066] In practice, any material or size can be used, depending on
the various needs.
[0067] Moreover, all details can be replaced by technically
equivalent elements.
[0068] The invention achieves important advantages.
[0069] Firstly, the presence of transmission means performing
simultaneously a pushing and a pulling action onto the support
makes the inversion of the direction of movement and the steps of
acceleration and braking gradual and smooth. This enables to limit
the size of the mechanical structure of the machine and the
stresses (vibrations, shakes, . . . ) it undergoes during
operation.
[0070] The structure of the machine is further simplified and made
lighter in both execution variants as described also thanks to the
particular shape of the movement means. As a matter of fact, in the
first execution variant the use of dedicated motors allows to
reduce the number of elements controlled by the central motor of
the machine, which can therefore be reduced in size. In this
embodiment, the structure of the machine is further reduced by
using electronic coordination means positively affecting also the
flexibility of the machine itself. In the second execution variant,
the complicated leverages of known machines are replaced by a
simple transmission system using preferably pulleys and belts. This
makes the knitting machine simpler to be carried out and managed,
especially as far as maintenance is concerned, and significantly
reduces the costs thereof. Furthermore, the use of a push-pull
system enables to balance the structure of the knitting machine and
to reduce significantly its vibrations. For instance, the knitting
machine according to the present invention allows to reduce
vibrations also at a speed of 3,000 and more oscillations per
minute.
[0071] Thanks to the lighter structure and the fewer vibrations,
the devices according to the present invention can operate at high
speeds reducing the criticalities of the knitting step with respect
to the other steps of the manufacturing process of knitted
items.
[0072] Finally, a further advantage consists in that the described
devices, by controlling the oscillating movement and ensuring a
high accuracy, ensure a high quality of the knitted items thus
manufactured.
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