US2817220A - Electronic controls for circular knitting machines - Google Patents

Description

24, '1957 I P. A. MAHL ER EIAL I 2,817,220

ELECTRONIC CONTROLS FOR CIRCULAR KNITTING MACHINES Filed Feb. 1, 1956 MOTOR 'AND ELECTRONIC cd'ufnol.

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' INVENTORS- PETER A. MAHLER JOHN T MCKIBBIN ATTYS Unite ELECTRONIC CONTROLS FOR CIRCULAR KNITTING MACHINES Application February 1, 1956, Serial No. 562,725

3 Claims. (Cl. 66-56) This invention relates to electronic speed controls for circular knitting machines of the character disclosed in prior United States Patent No. 2,422,568.

In the machine of the patent, means was provided for variably regulating the speed of the machine in accordance with the differing requirements of the several individual operations entailed in forming the end product. The speed variations were obtained through the medium of electronic control devices operatively associated with the electric motor constituting the prime mover of the machine, said devices including a potentiometer actuated directly from the pattern drum of the machine. By reason of technical advances, it has been found practicable to operate circular hosiery knitting machines of this class at relatively high rates of speed and to maintain the high speed constant throughout the forming of the entire stocking with exception only of one or more critical operations wherein it becomes necessary to greatly reduce the operating speed of the machine and, in shifting from one operation to another, where the mechanical moves entailed in the shift are such as to require a momentarily reduced speed. For example, the normal generally sustained operating speed may be of the order of 200 R. P. M., whereas in shifting from circular to oscillatory operation of the needle cylinder at the inception of the toe formation, it may be desirable or necessary to reduce the speed momentarily to as low as 40 R. P. M. or the equivalent.

Other operational shifts may require a speed reduction of considerably lesser but still substantial magnitudes. The prior speed control devices are not well adapted to changes of this magnitude. This is due in part to the fact that the shifts from one operation to another and the actuations of the speed control devices are under control of a common member, namely, the pattern drum so that the mechanical moves entailed in any operational change requiring a reduced knitting speed occurred simultaneously with the actuation of the speed regulating de vices and at the initial relatively high speed. While suitable for machines of the prior art, this type of control is not adapted to present high speed operation. An object of the present invention is to provide an improved speed control system wherein the reduction in speed is efiected in advance of the mechanical moves entailed in changing machine operations.

To this end, another object of the invention is to divorce the speed change function at least in part from the pattern drum so as to afford a high degree of flexibility in the relative timing of the mechanical moves effecting a change of machine operation and the speed change required for said moves or for the new operation.

Still another object is to provide a control system of the stated character characterized by relative simplicity of form and economy of installation.

The invention will be more readily understood by reference to the attached drawing which illustrates diagrammatically a control system made in accordance with the invention.

dtates Patet With reference to the drawing, the pattern drum which controls sequential operations of the machine is indicated by the reference numeral 1, and the numeral 2 indicates a ratchet wheel which is connected to the drum and constitutes an element of the drum indexing mechanism. A pawl 3, pivotally mounted at 4 on one arm 5 of a bell crank lever 6, constitutes the means for actuating the ratchet wheel 2 and for thereby indexing the drum, the lever being mounted on a rock shaft 7 which is oscillated continuously in timed relation with the rotary and oscillatory movements of the needle cylinder (not shown). A pattern chain 8, engaged with a sprocket 9, has attached thereto a ratchet wheel 10 which is actuated by a pawl 11, this pawl being pivotally attached at 12 to the other arm 13 of the lever 6, and being resiliently held in operative position with respect to the Wheel 10 by a spring 14. The ratchet wheel 10 and sprocket 9 are thus turned through a predetermined angle at each oscillation of the lever 6. It will be noted that during each working stroke of the pawl 11, the pawl 3 is being retracted, and vice versa.

The chain 8 carries longitudinally spaced lugs 15 which, as the chain is intermittently advanced as described, individually engage one end 16 of a lever 17 mounted at 18 on a fixed pivot, this lever 17 comprising at the opposite side of the pivot 18 an arm 19 positioned in proximity to one side of the ratchet wheel 2 for operative engagement with the pawl 3. When the lever end 16 is disengaged from the lugs 15 of the chain 8, as shown in the drawing, the said end 16 will be relatively depressed and the arm 19 relatively elevated so as to engage the end of the pawl 3 and to elevate the pawl in respect to the ratchet wheel 2 so that the pawl in its oscillatory movement will ride on the edge of the arm, 19 in a path remote to the ratchet wheel and will be. inoperative to actuate the latter. When the end 16 of the lever 17 is elevated by one of the lugs 15, the arm 19 will be retracted to release the pawl 3 to its normal operative position with respect to the ratchet wheel 2 so that in its working stroke the pawl will then be etfective to actuate the wheel and through the wheel to index the pattern drum 1. This mechanism is essentially the same as that disclosed in the aforesaid United States patent.

Also in accordance with the principle described in the. aforesaid patent, the machine comprises an electronic control device for effecting variations in the speed of the driving motor (not shown) which constitutes the prime mover of the machine. This device comprises an electronic unit 21 of a character described in the aforesaid patent and in conjunction therewith a potentiometer 22. In the prior device this potentiometer is actuated by a cam ring on the pattern drum to vary the operating speed of the machine as required by any one or more of the operations under control of the pattern drum. In the present invention, the potentiometer 22 is also actuated by a cam element on the drum 1, but the speed control does not in this case lie solely with the potentiometer 22 but lies in part with a second manually adjustable potentiometer 23 which under circumstances described below assumes a part of the speed regulating function.

In the present instance, the potentiometer 22 is set to a position which corresponds to the normal maximum operating speed of the machine, as shown in full lines in the drawing. This setting is obtained through the medium of a pinion 24 operatively connected to the potentiometer, a segmental gear 25 which meshes with the pinion 24, and a stop element 26 associated with the segmental gear 25 and serving to establish that gear in a position affording the said high speed setting of the potentiometer. A spring 27 exerts pressure through an arm 28 on the segmental gear 25 tending to hold that gear in engagement with the stop 26, as shown in full lines in the drawing. Thus under normal conditions, the potentiometer will be r tained at the setting affording the normal high speed operation. The segmental gear 25 may be shifted from its positionon the stop 26 by action of a cam 29 on the pattern druml, this cam moving with the drum in a path which will eventually bring it into operative engagement with the free end of an arm 31 operatively connected with the segmental gear 25. The arm 31 will normally occupy the full line position shown in the drawing. Displacement of the arm 31 by the cam 29 will displace the gear 25 angularly about the axis of its pivot 32 in clockwise direction as viewed in the drawing, and will thereby adjust the potentiometer 22 to a low speed position indicated in broken lines.

The lever 17 which is actuated by the lugs 15 of the pattern chain 8 as previously described, and which controls the position of the pawl 3 with respect to its ratchet wheel 2, is operatively associated with a microswtich 33 in a manner such that when the end 16 of the lever 17 is in the depressed position shown in full lines in the drawing, the switch 33 will be open as illustrated. When, however, the end 16 of the said lever is elevated by one of the lugs 15 of the chain, it will engage an actuating element 34 of the switch 33 and will close the latter. This closing of the switch 33 energizes solenoid 35 of a relay 36 and in so doing will cause the relay to open normally closed switch 37 and to close normally open switch 38. T1118 manipulation of the switches 37 and 38 substitutes the potentiometer 23 for the potentiometer 22 in the motor control circuit containing the source of energy 39 so that the control of the speed of the said motor now becomes a function of the potentiometer 23. The potentiometer 23 is manually pre-set to a position of intermediate motor speed so that the substitution of this potentiometer in the motor control circuit will result in an immediate reduction of speed from the normal high to a selected intermediate speed. As previously set forth, the potentiometer 23 is manually adjustable and may be set to any required or desired intermediate speed.

This transfer of potentiometers occurs on the forward or working stroke of the pawl 11 as previously described and during this working stroke, the pawl 3 has been retracted so that the subsequent reverse oscillation of the lever 6 will cause it to advance in its working stroke. The pawl control element 19 has been retracted at this juncture by action of the lug 15 of the chain 8 on the lever 17 so that the pawl 3 in its working stroke will operate to advance the ratchet wheel 2 and with it, the pattern drum 1. The resulting movement of the drum will bring the cam 29 on the latter into engagement with the arm 31 and will thereby effect a movement of the segmental gear 25 away from the stop 26 and, through the pinion 24, will adjust the potentiometer 22 to a loW speed position indicated in broken lines. This movement of the segmental gear 25 also results in the opening of a normally closed switch 41 in series relation with the switch 33, this actuation of the switch 41 being effected through an actuating element 42 located in the path of the arm 28 of the segmental gear. The opening of the switch 41 which occurs at the end of the angular movement of the segmental gear 25 and after the potentiometer 22 has been adjusted to low speed position, breaks the circuit of the solenoid 35 and results in again closing the switch 37 and opening the switch 38 so that the potentiometer 22 is now restored to the control circuit and the operation of the machine is reduced to the low speed to which the potentiometer 22 is now set. This low speed is below that at which the machine was operating under control of the potentiometer 23.

At the termination of this working stroke of the pawl 3 and the coinciding retractive movement of the pawl 11, the direction of movement of the lever 16 will be reversed with a resulting further indexing movement of the pattern chain 8. The lug 15 of the chain which now supports the end 16 of the lever 17 is of such extent that this indexing movement of the pattern chain fails to release the lever 17 from the lug so that the switch 33 remains closed and the arm 19 of the lever 17 remains in the retracted position permitting the pawl 3 to engage the ratchet wheel 2. The subsequent forward movement of the pawl 3, therefore, againindexes the pattern drum. In the present instance, this indexing movement performs two functions. The initial part of the movement effects the machine adjustment the performance of which has required the reduction to low speed operation. Such adjustment might, for example, reside in the shifting of a clutch to change the full rotary movement of the needle cylinder to oscillatory movement, more particularly in initiating formation of the toe of the stocking. During that portion of the indexing movement of the drum 1 wherein this machine adjustment is effected, the arm 31 is still held in the elevated position by the cam 29, but continued movementof the drum eventually releases the arm 31 from the cam and permits the segmental gear 25 under actuation by the spring 27 to return to the original position against the stop 26. This movement of the segmental gear first releases the actuating element 42 of the switch 41 and permits that switch to close; and subsequently readjusts the potentiometer 22 to the original high speed position. Since the end 16 of the lever 17 remains in'the elevated position on the lug 15 and the switch 33 is therefor closed, the closing of switch 41 energizes the solenoid 35, again opening switch 37 and closing switch 38 and thereby transferring the control of machine speed to the potentiometer 23. The machine then assumes the intermediate speed to which the potentiometer 23 has been set manually. This intermediate speed of operation continues until the next forward movement or working stroke of pawl 11 which results in a further indexing movement of the chain 8 releasing the lever 17 from the lug 15 and permitting the lever to return to the original position shown in the drawing in which the arm 19 serves to elevate the pawl 3 from operative position with respect to the ratchet wheel 20. Release of the lever 17 also results in the re-opening of the switch 33 which breaks the circuit of solenoid 35 de-energizing the latter closing switch 37 and opening switch 33 thereby restoring con trol of machine speed to the potentiometer 22 which now, as described above, occupies the original high speed position.

It will be noted that in this sequence of operation, the transition between the high and low speeds occurs in each direction through the intermediate low speed. It will be noted further that the period of low speed operation is reduced to a minimum consistent with the performance of the machine adjustment requiring the low speed operation.

The sequence of operations set forth above is illustrative only of the principle of the invention. Indexing of the pattern drum may be effected in part, for example, independently of the pawl 3 by auxiliary indexing pawls in accordance with well known principles, and the ability afforded by the invention to transfer in part the speed control function from pattern drum to a separate pattern chain materially increases the flexibility of control in respect particularly to the high speed operations of the modern machine. It will be understood that the device may be utilized at any point or points in the production of a stocking unit by provision of suitable cams on the drum and lugs on the pattern chain to regulate the speed of the machine as required. Where two successive knitting operations may be conducted at the high speed, and the shift from one operation to the other requires a temporary speed reduction to the intermediate range only, the said reduction may be affected by substitution in the control circuit of the potentiometer 23 through the medium of the pattern chain and Without recourse to the pattern drum cam, the control being restored immediately to the potentiometer 22 at the original high speed setting. It will be noted, however, that in each change of operation accompanied by a reduction or speed, the said reduction will occur before the mechanical moves are made which elfect the said operational change.

I claim:

1. A circular knitting machine comprising an electric motor constituting the prime mover for the machine, a pattern drum for governing predetermined operations of the machine, a pattern chain for governing the operations of said drum, an electronic speed control circuit for and including said motor, a variable control unit for said circuit adjustable to efiect variations in the speed of said motor in accordance with variations in the operations of the machine as prescribed by said pattern drum, means for relatively adjusting said unit including a cam follower and a cam carried by the pattern drum and engageable with said cam follower, a second and independent control unit for said circuit, means for selectively and individually connecting said control units in said circuit, and means including separate switch means responsive respectively to movements of said drum and chain for actuating said connecting means to selectively and individually connect said units in the circuit.

2. A circular knitting machine comprising an electric motor constituting the prime mover for the machine, a pattern drum for governing predetermined operations of the machine, a pattern chain for governing the operations of said drum, an electronic speed control circuit for and including said motor, separate control units for said circuit for regulating the speed of the motor, means for selectively and individually connecting said control units in the circuit, an electrical actuator for said connecting means, a pair of separate control switches for said actuator arranged in series with the actuator and with each other, and means carried by the drum and said chain for actuating said switches in response respectively to movements of said drum and chain to connect the said units individually in said circuit in accordance with variations in the operations of the machine as prescribed by the pattern drum.

3. A circular knitting machine comprising an electric motor constituting the prime mover of the machine, pattern mechanism for governing predetermined operations of the machine, an electronic speed control circuit for and including said motor, and means for varying the speed of said motor in accordance with variations in the operations of the machine as prescribed by said pattern mechanism, said speed varying means including separate control units for said circuit, means for selectively and individually connecting said units in the circuit, and means actuated by the pattern mechanism for operating the control unit connecting means in accordance with variations in the machine operations as prescribed by the pattern mechanism.

References Cited in the file of this patent UNITED STATES PATENTS Larkin June 17, 1947

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