US3097511A

US3097511A - Warp knitting machines

Info

Publication number: US3097511A
Authority: US
Priority date: 1956-03-16
Publication date: 1963-07-16
Anticipated expiration: 1980-07-16
Also published as: DE1165799B; DE1729736U

Description

y 1963 A. w. H. PORTER 3,097,511

WARP KNITTING MACHINES 7 Filed March 11, 1957 2 Sheets-Sheet l Inventor I /4//an W/XPoraer Attorneys y 1963 A. w. H. PORTER 3,097,511

WARP KNITTING MACHINES Filed March '11, 1957 2 Sheets-Sheet 2 Inventor B M AttornZs United States Patent 3,097,511 WARP KNITTING MACHINES Ailan Wiiliam Henry forter, Burton-on-Trent, England, assignor to Hohonrn-F.N.F. Limited Filed Mar. 11, 1957, Ser. No. 64:5,tifl3 Claims priority, application Great Britain Mar. 16, 1956 17 Claims. (Cl. 66-86) This invention relates to mechanisms for controlling the tension in the warp threads of high speed warp knittlng machines.

A mechanism for this purpose has been used which comprises a tension bar over which the threads are led, and which is mounted on a support in which there are two resilient connections of different strengths and natural frequencies of vibration. The weaker connection deflects to absorb fluctuations which occur in the tension of the warp threads during each knitting cycle, and the stronger connection yields substantially only under a persistent increase in the mean tension of the threads. The movement of a member carried by the stronger resilient connection is used to control a mechanism which changes the speed of rotation of the warp beam and so adjusts the tension in the Warp threads as necessary.

The fluctuations in the tension of the threads which occur in each knitting cycle are cyclical and produce a vibration in the Weaker resilient connection, the frequency of which is equal to the number of courses knitted per second by the machine. In order that resonance does not occur, the natural frequency of the weaker resilient connection must be higher than the frequency at which it is thus caused to vibrate. To obtain the high natural frequenoy which is thus necessary, which must usually be over 1500 cycles per minute, the Weaker resilient connection must have considerable stiffness. Since of course, the stronger connection is even stiffer a persistent increase in tension of the Warp threads of considerable magnitude is necessary to cause the stronger resilient connection to yield and so vary the speed of the warp beam. The mechanism cannot therefore, be made to respond sensitively.

According to the present invention, the tension bar over which the threads are led, is connected through a stronger resilient connection to a speed-control member, movement of which actuates a mechanism for adjusting the speed of rotation of the warp beam, the speed-control member being connected through a weaker resilient connection to a fixed support and also being connected to a device which acts to damp out oscillations in the member at frequencies of the order of that at which the machine operates.

A fluid damping device may be used, for example, one in which a vane is caused to move through a viscous fluid, or a dash-pot in which a piston moves within a cylinder and forces fluid through a restricted orifice.

Preferably, however, the device comprises a mass which is large compared with that of the tension bar, the speedcontrol member being connected to the large mass through a mechanism which, when actuated by movement of the member, causes a greater movement of the large mass.

The tension bar is enabled to vibrate due to yielding of the stronger resilient connection in response to the cyclical fluctuations in the tension of the warp threads, but due to the action of the damping device the member to which the tension bar is connected is not able to respond, and the weaker resilient connection is not appreciably deflected. However, as soon as a persistent increase in the tension of the warp threads occurs, the weaker resilient connection can respond readily without it being necessary for a large deflection of the stronger connection to take place first and consequently, the speed of the warp beam is quickly adjusted as necessary to correct the persistent change in tension.

The large mass must be arranged so that it is in neutral equilibrium and thus when it is moved, it does not exert any restoring force on the member to which the tension bar is connected which moves only against the weaker resilient connection. For this reason, the large mass is preferably a flywheel. A fly-wheel having a low fre quency characteristic will, however, allow oscillation of the whole system to take place when, during starting and stopping, the frequency of the machine is about the same as that of the fly-wheel and weaker resilient connection. To prevent this happening 3, fluid damping device may be used in conjunction with the fly-wheel and in this case may be connected to the fly-wheel itself.

An example of a knitting machine constructed in accordance with the invention is illustrated in the accompanying drawings in which:

FIGURE 1 is a diagrammatic side elevation of the mechanism fitted on a warp knitting machine.

FIGURE 2 is a side elevation of the mechanism in detail.

FIGURE 3 is an elevation of the mechanism viewed from the opposite side of FIGURE 2.

FIGURE 4 is a diagrammatic view showing the mechanism electrically connected to a variable speed gearing for driving the warp beam.

As shown in FIGURE 1, a sheet of warp threads 1 pass from a Warp beam 2, over a tension bar 3 and so down to the knitting point. A further sheet of warp threads 4 pass from a Warp beam 5 to the knitting point over a tension bar 6. The tension bar 3 is carried at intervals by spring cantilevers 7 from a shaft 8 and the tension bar 6 is carried by similar arms 9 from a shaft 10. Both the shafts 3 and'ltl are carried at each end of the machine in bearing bushes in brackets 11, which are fixed to a frame 12 of the machine.

As shown in FIGURE 2

sleys

2a and 5a are provided for guiding the sheets of warp threads as they pass from the warp beams to the tension bars 3 and 6 respectively;

and a bell-crank lever 13 is fixed to the shaft 8 and a sim ilar bell-crank lever 14 is fixed to the shaft .11). One arm of the bell-crank lever :13 is formed as a toothed quadrant 15 and meshes with a pinion 16 which is fixed on a stub shaft 17 extending through a bearing in the bracket 11. The stub shaft 17 carries a fly wheel 18 at its end remote from the pinion 16. A rod 18a is pivotally fixed to the second arm 19 of the bell-crank lever 13 and is surrounded by a coiled compression spring 19a which abuts at one end against a lug 20 which is fixed to the bracket 11 and at the other end against a knurled nut 21 on the rod 18a.

One arm 22, of the bell-crank lever 14 meshes with a pinion 23 which is exactly similar to the pinion 16 and which is connected to a fly-wheel 24. A second arm 25 of the bell-crank lever 14 carries a spring 26 which op crates in a similar manner to the spring 19a. The flywheel 18 carries a blade 27 which is positioned between

arms

28 and 29 of micro-switches 30 and 31 respectively. The fly-wheel 24 carries a blade 32 which is similarly positioned between arms 33 and 34 of micro-switches 35 and 36. The positions of the micro-switches 3t), 31, 35 and 36 can each be adjusted "by

micrometer screws

37, 38, 39 and 40.

As shown in FIGURE 4 the micro-switches 3t) and 31 are included in control circuits of an electric motor 41. The motor 41 controls a variable speed gearing 42 included in the drive transmission of the warp beam 2.

The variable speed gearing 42 comprises an input shaft 43 on which a cone 44 is fixed. An idle cone 45 is rotatably mounted beside the cone 44 and -a third similar cone 46 is fixed on an output shaft 47 which either drives the warp beam 2 directly or actuates a mechanism for adjusting its speed of rotation, as hereinafter described. The drive is transmitted frictionally from the cone 44 to the cone 45 by a ring 48 and similarly to the cone 46 by a second ring 49. The ratio of the gearing thus depends on the positions of the

rings

48 and 49 along the axes of the cones. The position of the ring 48 may be varied by rotating a screw-threaded shaft 5G by hand and that of the ring 49 by rotating a similar shaft 51 by means of the motor 41. In the illustrative example, the input shaft 43 of the variable speed gearing 42 is rotated by the main driving motor of the machine, which is not shown, and the output shaft 47 is coupled to either one of the warp beams to drive the warp beam continuously.

As the tension in the sheet of warp threads I fluctuates during each knitting cycle the cantilever springs 7 which are relatively stiff and have a high natural frequency deflect and enable the tension bar 3 to vibrate. The shaft 8 is however, prevented from deflecting against the action of the relatively weak spring 19a because of the inertia of the fly wheel 18. When, however, a persistent increase in the tension of the sheet of warp threads 1 occurs, the tension bar 3 is pushed downwards and the shaft 8 is rocked in a clockwise direction as seen in FIG- URE 2. The bell-crank lever \13 therefore, also rotates in a clockwise direction and rotates the pinion 16 through an angle approximately seven times as great because the radius of the quadrant 15 is approximately seven times as great as the radius of the pinion 16. The blade 27 is thus pushed against the arm 29 which closes the microswitch 31. The shaft 8 forms the speed-control member, movement of which actuates the mechanism for adjusting the speed of the warp beam. In this particular example, the blade 27 which actually operates the speed controlling switch is fixed to the fly-wheel 18 instead of the speed control member itself to increase the sensitivity of the mechanism.

The motor 41 is energised by closure of the microswitch 31 and rotates the shaft 51 in a counterclockwise direction thus moving the ring 49 downwards and so increasing the speed of the warp beam.

If a persistent decrease in the tension of the warp threads occurs, the blade 27 is pushed against the arm 28 and closes the micro-switch 30. The motor 41 is again energised, but in this case rotates the shaft 51 in a clockwise direction and moves the ring 49 upwards so decreasing the speed of the warp beam.

The increase or decrease in the speed of the warp beam causes a decrease or increase in the tension of the warp threads as necessary.

The tension of the sheet of warp threads 4- is controlled in an exactly similar manner.

I claim:

1. A high speed flat warp knitting machine having a mechanism for controlling the tension in the warp threads by adjusting the speed of notation of a continuously driven wanp beam, the mechanism comprising a tension bar over which the threads are led and which is connected through a resilient connection to a speed-control member, movement of which :actuates a mechanism for adjusting the speed of rotation of the warp beam, the speed-control member being connected through -a weaker resilient connection to a fixed support and also being connected to a device which acts to damp out oscillations in the member at frequencies of the order of that at which the machine operates.

2. A knitting machine according to claim 1, in which the damping device comprises a mass which is large compared with that of the tension bar and which is connected to the speed-control member by a mechanism, which when actuated by movement of the member causes a relatively greater movement of the mass.

3. A knitting machine according to claim 2, in which the mass is a fly-wheel and the speed-control member is pivotally mounted.

4. A knitting machine according to claim 3, in which a pinion of small radius is rigidly connected to the flywheel and a toothed quadrant of large radius which [l meshes with the pinion is rigidly connected to the speedcontrol member.

5. A knitting machine according to claim 2, in which the mechanism for adjusting the speed of rotation of the warp beam includes an arm fixed to the mass which, upon movement of the mass, closes either one or other of a pair of switches to complete either an electrical circuit which increases the speed of rotation of the warp beam or an electrical circuit which decreases the speed of rotation of the warp beam, depending on the direction of movement of the mass.

6. A knitting machine according to claim 5, in which the distance through which the arm must move to close either one or other of the switches is adjustable by micrometer screws.

7. In a high speed fiat warp knitting machine includ ing a warp beam and variable speed driving means for rotating said warp beam, a mechanism for controlling the tension of the warp threads by adjusting the speed of said driving means, said mechanism including a fixed support, a speed control member movably mounted on said fixed support and operatively connected to said variable speed driving means to adjust the speed thereof, a relatively weak resilient connection resisting movement of said speed control member relatively to said fixed support, a tension bar over which said warp threads pass, a relatively strong resilient connection connecting said tension bar to said speed control member and damping means connected to said speed control member to prevent said member from oscillating in response to vibrations transmitted from said tension bar at frequencies of the order of that at which the machine operates.

8. In a high speed flat warp knitting machine including a warp beam and variable speed driving means for rotating said warp beam, a mechanism for controlling the tension of the warp threads by adjusting the speed of said driving means, said mechanism including a fixed support, a speed control member movably mounted on said fixed support and operatively connected to said variable speed driving means to adjust the speed thereof, a relatively weak resilient connection resist-ing movement of said speed control member relatively to said fixed support, a tension bar over which said warp threads pass, a relatively strong resilient connection connecting said tension bar to said speed control member, a mass, which is large compared with that of said tension bar, movably mounted on said fixed support and means operatively connecting said speed control member to said mass, to cause a relatively large movement of said mass in response to a relatively small movement of said speed control member, whereby vibrations transmitted to said speed control member from said tension bar at frequencies of the order of that at which the machine operates are prevented from causing said speed control member to oscillate with sufficient amplitude to affect said variable speed means.

9. A high speed fiat warp knitting machine as claimed in claim 8, comprising electrical means for adjusting said variable speed driving means, a first circuit for energizing said electrical means to increase the speed of said variable speed driving means, a second circuit for energizing said electrical means to decrease the speed of said variable speed driving means, an arm fixed to said mass for movement therewith, a first switch in said first circuit, a second switch in said second circuit and actuating means for said switches in the path of movement of said arm, whereby movement of said mass in one direction causes said arm to close said first switch to complete said first circuit and movement of said mass in the other direction causes said arm to close said second switch to complete said second circuit.

10. A high speed flat warp knitting machine as claimed in claim 9, further including micrometer screw means for adjusting the position of said actuating means along the path of said arm.

11. In a high speed fiat warp knitting machine including a warp beam and variable speed driving means for rotating said :warp beam, a mechanism for controlling the tension of the wanp threads by adjusting the speed of said driving means, said mechanism including a fixed support, a speed control member pivotally mounted on said fixed support and operatively connected to said variable speed driving means to adjust the speed thereof, a relatively weak resilient connection resisting movement of said speed control member relatively to said fixed support, a tension bar over which said Warp threads pass, a relatively strong resilient connection connecting said tension bar to said speed control member, a flywheel, the mass of which is large compared with that of said tension bar, mounted on said fixed support and means operatively connecting said speed control member to said flywheel to rotate said flywheel through a relatively large angle in response to a relatively small angular movement of said speed control member, whereby vibrations transmitted to said speed control member from said tension bar at frequencies of the order of that at which the machine operates are prevented from causing said speed control member to oscillate with suflicient amplitude to affect said variable speed means.

12. A high speed flat warp knitting machine as claimed in claim 11, in which said means operatively connecting said speed control member to said flywheel includes a pinion of relatively small radius rigidly connected to said flywheel and a toothed quadrant of relatively large radius which meshes with said pinion and is rigidly connected to said speed control member.

13. A high speed flat warp knitting machine as claimed in claim 11, comprising electrical means for adjusting said variable speed driving means, a first circuit for energizing said electrical means to increase the speed of said variable speed driving means, a second circuit for energizing said electrical means to decrease the speed of said variable speed driving means, an arm fixed to said flywheel for movement therewith, a first switch in said first circuit, a second switch in said second circuit and actuating means for said switches in the path of movement of said arm, whereby rotation of said flywheel in one direction causes said arm to close said first switch to complete said first circuit and rotation of said flywheel in the other direction causes said arm to close said second switch to complete said second circuit.

14. A high speed flat warp knitting machine as claimed in claim 13, further including micrometer screw means for adjusting the position of said actuating means along the path of said arm.

15. A high speed flat warp knitting machine, includ ing a warp beam, a variable speed gearing for rotating said Warp beam, and a mechanism for controlling the tension of the warp threads by adjusting the ratio of said variable speed gearing, said mechanism including an electric motor operatively coupled to increase the ratio of said variable speed gearing on rotation in one direction and to reduce the ratio of said variable speed gearing on rotation in the other direction, a first circuit for energizing said motor for rotation in said one direction and a second circuit for energizing said motor for rotation in said other direction, a fixed support, a speed control member pivotally mounted on said fixed support, a relatively weak resilient connection resisting movement of said speed control member relatively to said fixed support, a tension bar over which said warp threads pass, a relatively strong resilient connection connecting said tension bar to said speed control member, a flywheel, the mass of which is large compared with that of said tension bar, mounted on said fixed support and means operatively connecting said speed control member to said flywheel to rotate said flywheel through a relatively large angle in response to a relatively small angular movement of said speed control member, an arm fixed to said flywheel for movement therewith, a first switch in said first circuit, a second switch in said second circuit and actuating means for said switches in the path of movement of said arm, whereby rotation of said flywheel in one direction causes said arm to close said first switch to complete said first circuit and rotation of said flywheel in the other direction causes said arm to close said second switch to complete said second circuit and whereby vibrations transmitted to said speed control member from said tension bar at frequencies of the order of that at which the machine operates are prevented from causing said speed control member to oscillate with suflicient amplitude to aflect said variable speed gearing means.

16. In combination with a warp knitting machine or the like of the type having knitting elements, a warp beam for supplying webs of fibrous material, warp threads or the like to said elements, and driving means for rotating said warp beam which includes a variable driving gear, electric control means for controlling the operation of said driving means, a first tension control member interposed between said warp beam and said knitting elements and in engagement with said Warp threads, said tension control member being oscillated under control of said threads about a mean position corresponding to a mean tension of said threads, a second control member connected to said first control member for movement thereby in one direction or the other from a central normal position in accordance with a persistent movement in said direction of the mean position of successive oscillations of said first control member, means for damping the motion of said second control member, and means actuated by movement of said second control member for actuating said electric control means when said second control member moves a predetermined distance in either direction from its central normal position.

17. A high speed Warp knitting machine as claimed in claim 16 in which said damping means damps the movement of said second control member With equal eflectiveness at all positions of said second control member and regardless of its direction of movement.

References Cited in the file of this patent UNITED STATES PATENTS 2,582,972 Dungler Ian. 22, 1952 2,664,724 Lambach et al. Jan. 5, 1954 2,720,093 Lambach et al. Oct. 11, 1955 2,801,308 Cubellis July 30, 1957 FOREIGN PATENTS 718,097 Great Britain Nov. 10, 1954

Claims

1. A HIGH SPEED FLAT WARP KNITTING MACHINE HAVING A MECHANISM FOR CONTROLLING THE TENSION IN THE WARP THREADS BY ADJUSTING THE SPEED OF ROTATION OF A CONTINUOUSLY DRIVEN WARP BEAM, THE MECHANISM COMPRISING A TENSION BAR OVER WHICH THE THREADS ARE LED AND WHICH IS CONNECTED THROUGH A RESILIENT CONNECTION TO A SPEED-CONTROL MEMBER, MOVEMENT OF WHICH ACTUATES A MECHANISM FOR ADJUSTING THE SPEED OF ROTATION OF THE WARP BEAM, THE SPEED-CONTROL MEMBER BEING CONNECTED THROUGH A WEAKER RESILIENT CONNECTION TO A FIXED SUPPORT AND ALSO BEING CONNECTED TO A DEVICE WHICH ACTS TO DAMP OUT OSCILLATIONS IN THE MEMBER A FREQUENCIES OF THE ORDER OF THAT AT WHICH THE MACHINE OPERATES.