US2231662A - Hosiery machine drive - Google Patents

Description

Feb. 11, 1941.

c. w, BRAKE ETAL HOSIERY MACHINE DRIVE Filed Nov. 12, 1957 3 Sheets-Sheet 1 lNvENToRs 675615161' Drake and Knit/ing Mac/zine will R. ara/ing.

Feb. 11, 1941. c, .w' BRAKE ENL- 2,231,662

HOSIERY MAICHINE DRIVE Filed Nov,A 12, '1931 3 sheets-sheet 2 Patented Feb. 11, 1941 UNITED STATES' PATENT OFFICE HO SIERY MACHINE DRIVE Application November 12, 1937, Serial No. 174,201

14 Claims.

Our invention relates, generally, to variable speed machinery drives, and, more particularly to a system of speed control for full-fashioned hosiery knitting machines.

In the operation of fullfashioned hosiery machines,l it is necessary that the machine be driven at different speeds for the several different steps in the knitting process. A very low speed, approximately 10 to 15 percent of the normal highest knitting speed, is necessary while the machine is being started and while the welt is being turned. During the forming of certain parts of the hose, a speed of approximately 80 percent of the highest knitting speed is necessary.

While the number of knitting stitches per course is being reduced to produce a narrowing of the hose, a speed of approximately 35 to 40 percent of maximum knitting speed is required. This is known as the narrowing process and the speed is reduced from normal running speed only during the short interval necessary for reducing the number of stitches in the courses.

It is necessary that a high torque be maintained throughout the range of speeds of 10 percent to maximum andvery considerable difficulty has been experienced in providing a drive system that will satisfy the desired speed and torque requirements.

An object of our invention is to provide a control system for an electric motor driven fullfashioned hosiery machine which shall function to provide a wide range of speeds while maintaining a high torque.

Another object of the invention is to provide a control system for an electrically driven fullfashioned hosiery machine which shall function to automatically govern the speed of the machine to provide the necessary speed for the several operations of the machine.

A further object of the invention is to provide a motor control system for an induction motor driven machine which shall function to provide a wide range of speeds for the machine while maintaining a desirable speed-torque characteristic at extremely low speeds.

These and other objects and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a diagrammatic illustration of a preferred embodiment of the invention showing the cooperative relationship of the several elements of the control system.

Fig. 2 is a diagrammatic illustration of another embodiment of the invention in which additional automatic features are included.A

Figs. 3 and 4 are charts showing the conditions of the relays and switching devices of the control systems of Figs. 1 and 2, respectively, for 5 producing the desired speeds, and

Fig. 5 is a chart showing the approximate speed-torque characteristics of a motor under control of the systems of Figs. l and 2.

In practicing the invention, weprovide relay means for varying the resistance in the rotor circuit of an induction motor to vary the motor speed within the higher speed ranges. Control of the motor to secure extremely low speeds is provided by varying the load on a generator driven by the motor. The actuation of the relays is under manual control for certain of the speeds and automatic control for other speeds.

Referring to Fig. 1 of the drawings, a knitting machine is driven by a wound rotor induction motor l0 which is energized from the alternating current power source XYZ through the contact elements l2 of relay I. The wound rotor circuit of the motor I0 has variable resistances i4 and I6, I8 and 20, 22 and 24 in its three branches 25 and connections are made through the contact `elements 26 of relay 2 and 28 'of relay 3 for shorting out various values of these resistances so as to vary they resistance in the wound rotor circuit and in this manner vary the speed torque 30 A characteristic of the motor l0.

A series excited generator 30 is connected to be driven by the motor I0 and a resistance 32.may be connected in series circuit relation with generator 30 through the contact element 34 of 35 relay 4. A circuit is arranged through contact element 36 of relay 5 for shorting out a part of the resistance 32 to vary the load on the generator 30.

Whenl the rotor circuit is controlled by contact elements 26 of relay 2, the minimum of resistance is connected in the rotor of the motor i0 and the motor will have a speed torque characteristic whichwill rbe a curve which will lie between the curves A and B of Fig. 5, depending upon the values of the resistance in the rotor circuit which, in turn, depend upon the position of the movable contacts on the variable resistors Il, I6 and 22. The speed of the knitting machine under these conditions at the torque re- 5o quired for operating the knitting machine would lie somewhere between the intersections of lines A and B of Fig. 5 and the broken line ordinate which will represent knitting machine speeds of between and 75 courses per minute.

When only contact elements 28 of relay 3 are closed, such a resistance will be connected in the rotor circuit of motor I0 as will give it the speed torque characteristics which will lie between the curves B and C of Fig. 5, depending upon the amount of the resistance in the motor circuits, which is variable as stated hereinbefore, and this speed range will represent a knitting machine speed of between 40 and 60 courses per minute.

With contact elements 26 and 28 in the open circuit position, and contact element 34 of relay 4in the closed circuit position, the generator 30 and its connected resistance 32 will constitute such a load upon the motor I0 as to give it a net speed torque characteristic as is represented by the curve D of Fig. 5, the net torque in this instance being the torque required by the knitting machine itself, disregarding the torque required by the loaded generator 3U. It will be seen that the knitting machine speed atl its required torque will be approximately 30 courses per minute under these conditions.

When it is necessary that the knitting machine be operated at a still lower speed, contact element 36 of relay 5 is closed to short out part of resistance 32 and thus increase the load on the generator 30. The net speed torque characteristic curve of the motor under these conditions is represented by the curve E of Fig. 5, and it will be seen that a knitting machine speed of approximately 8 courses per minute is produced under these conditions.

Relay I is controlled by a circuit which extends from one conductor Y of the source of alternating current through conductor 38, conductor 40, control device 42 in its MI position, conductor 44, the contacts of limit switch CC, conductors 46 and 48, the coil of relay I and conductors 50 and 52 to another conductor Z of the source of alternating current. After relay I has been energized, it will be seen that it closes its Contact element 54 which completes a holding circuit for relay I through conductor 56 and the control device 42 when the control device is in positions M2 and M3.

The relay 2 is controlled by a circuit which extends from the conductor Y of the source of alternating current through the conductors 38 and 48, contact element 54, conductor 56, control device 42 in the M3 position, conductor 58, contact element 60 of relay 5, conductor 62', the coil of relay 2, contact element 64 of relay 3, and the conductor 52 to the conductor Z of the source of alternating current.

The control circuit of relay 3 extends from the conductor Y of the source of alternating current through conductor 38, to control device 42 either through conductor 40 or through conductor 4U, contact element 54 and conductor 56,conductor 44, the contacts of limit switch CC, conductor 46, the contact elements of the limit switch N, conductor 66, the contact element 88 of relay 5, conductor 10, the coil of relay 3 and the conductor 52 to the conductor Z of the source of alternating current.

The control circuit for relay 4 extends from the conductor Y of the source of alternating current through conductor 38, either conductor 48 or conductor 40, contact element 54 and conductor 58, the control device 42, the conductor 44, the contacts of limit switch CC, conductors 48, 48 and 12, the coil of relay 4, conductor 14, contact element 'I6 of relay 2', conductor 18, contact element 80 of relay 3 and conductor 52 to conductor Z of. the source of alternating current.

A similar circuit is established @through relay 5 between conductors 48 and 52 by conductor 82, the coil of relay 5, conductor 84, switch element 8C and conductor 86.

A control device 88 driven, as shown, in synchronism with the knitting machine is provided for actuating the limit switches N and CC after predetermined numbers of courses have been knitted. The control device 88 comprises a series of belt 90 and 82 upon which are mounted protuberances 94 in such positions and of such length as to hold the contacts of the limit switches N and CC in open circuit position for the desired intervals at the desired points in the process of knitting. The limit switch N is provided for produc- 'ing the "narrowing speed which is a speed of approximately 30 courses per minute, which is necessary in the knitting of the hose to permit reducing the number of stitches per course in the stocking. This speed is maintained for only very short intervals and it is, therefore, necessary that the protuberances 94 be very narrow so that limit switch N will be held in open circuit position for only a short time.

The contacts of the limit switch CC are connected to deenergize the relay I and, therefore, to deenergize the motor I0 at certain predetermined intervals in the knitting operation when certain machine adjustments must be made with the knitting machine idle.

Fig. 3 of the drawings shows the position of the various control switches and the several relays for producing the desired operating speeds ofthe knitting machine. In the usual cycle of operation for knitting full-fashioned hose, a speed of approximately 8 courses per minute is iirst produced to get the machine started. A knitting speed of from 60 to 75 courses per minute is then produced to knit the welt of the hose. While the Welt is being turned, a speed of approximately 8 courses per minute is necessary. For normal knitting, the high speed of from 60 to 75 courses per minute is used. During the narrowing operation, a speed of approximately 30 courses per minute is employed andfor certain parts oi the knitting, it is necessary that a slow speed of from 40 to 60 courses per minute be provided. The chart of Fig. 3 illustrates which switches and relays are closed and energized to produce the various speeds necessary by the system of Fig. 1.

In the operation of the device of Fig. l, the starting speed is produced by closing a push button switch 8C and moving control device 42 to the MI position. It will be seen that this switching operation will cause relay I to energize the motor I0 through its contact elements I2, relay 5 will be operated to close its contact element 36 and relay 4 will be energized to close its contact element 34. The circuit of relay 2' will remain open, since its complete circuit depends upon the control device 42 being in the M3 position and the circuit of relay 3 will be opened by contact element 68 of relay 5. Thus, it will be seen that the motor I0 will have a net speed torque characteristic approximately as represented by the curve E of Fig. 5, and that the knitting machine will be operated at a speed of approximately 8 courses per minute. Y

When it is desired to run the knitting machine at high speed, control device 42 is moved to the M3 position and the push button switch 8C is I moved to open circuit position, In this step of the operation of the system, it will be seen that relays will be closed, producing the speed torque char- Il aaaisa lines A and B of Fig.5,'or a speed of from 60 to 'I5 courses per minute depending upon the position of the movable contacts upon the variable resisl tors Il, I3 and 22. Itwillbeseenthatwith relays 2 and 3 energized, contact elements Il and Il will be in the open circuit position toinsure that the relay l be deenergized. K

After the welt of the stocking is knitted and is ready to be turned, a 'speed of approximately 8 courses per minute is produced by closing the push button switch'lC with the control devicer 42 in the M3 position. This will produce the desired speed by energization of the relays described herei'nbefore in connection with the starting speed of the knitting machine.

After the welt is turned, the normal high speed of from 60 to' 75 courses per minute is again produced by moving the push button switch 3C to the open circuit position.

After knitting has progressed at the high knitting speed to where it is necessary to perform the narrowing action, the belt 9| will have moved to such a position as to cause one of the protuberances 24 to engage the limit switch N and open its contacts. It will be seen that this operation will cause relay 3 to be deenergized, which will close its contact element Il and open its contact element 04. The opening of contact element 64 will cause the deenergization of relay 2 and its contact element I3 will close to complete a circuit through relay l. With only relay l energized, all of the resistance 32 will be lconnected in circuit with the generator andthe knitting machine speed of approximately 30 courses per minute will be produced, since the motor i0 will then have the characteristic substantially as illustrated by curve D in Fig. 5.

For producing the slow knitting speed, of from 40 tof'60 courses per minute, control device l2 is moved to the M2 position while relays 2-and 3 are energized, thus deenergizing relay 2 and leav-y ing only the relay 3 energized. With only relay 3 energized, lcontact elements 23 will connect such a resistance in the rotor circuit of the motor Ill as to produce the speed torque characteristics represented by the range of characteristics between lines B and C in Fig. 5.

The operation of the lixnit switch CC is obvious from the drawings, since its contacts-are connected in series circuit relation with relay I whichcontrols the energization ofthe motor Il through its contact elements I2. Should this limit switch operate while the control device l2 is in the M3 position, it will be seen that the machine will be shut down until the control device is again moved to the Mi position, since the stick circuit comprising contact element N and conductor li upon which the energization of relay I depends while the control device I2 is in the M3 position, is opened by the deenergization of relay i and the consequent movement of the contact element Il to the open circuit position.

The modiiication of Fig. 2 is similar to that of ,Fig 1, vbut has. in addition, automatic control.

tor the slow knitting speed and the welt turning speed, so that these speeds are produced auto-v a holding circuit for vI and contact elements I2 whichconnectthemotor Iltothe al,

. ternating current source indicated by conductors relation with the coil of relay 2 to connect relay 1o 2I in the circuit corresponding to the ,circuit through relay 2 controlled by the M3 position of controller I2 of Fig. 1. Relay 2-is alsofconnected in series circuit relation with the normally closed limit switch SL which is operated by Dro- 15 tuberances $4 on web I3 of the control device Il,

The circuit of relay 3, which operates its contact elements 23. to connect only a part of the resistances It, 2l, 24 in the rotor circuit 'of the motor il to produce the slow knitting speed is 20 controlledV by normally closed contact element il of relay l and normally closed contact element Il of relay 2,

Relay 4 which closes its contact element 3l to connect the resistance 32 to placca load 25 upon the generator 33 is controlled by the contact element 3l of relay 3.

The relay 5, which actuates its contact element 33 to increase the load on generator 33, is

controlled by push button switch 2C, as described 30 in connection with the device of Fig. 1, and this push button switch 8C is paralleled by normally open contact elements of limit switch W which are controlled by protuberances 34 on the,web IBI of the control device Il sothat the welt turning speed may be produced automatically after the desired number of courses have been' knit in the welt. It will be seen that the contact element 6l of relay 5 of the device of Fig. 2 serves the purpose or both contact nements ce and al 4 of the device of Fig. 1, since the contact Il controls both relays 2 and 3 in the device of Fig. 2.

The chart of Fig. 4 shows the position of Ithe various switches and the energization of the relays oi the device of Fig. 2l for the several conditions of operation for'producing the several necessary knitting speeds. In the operation of the device of Fig. 2, the slow starting speed of 8 courses per minute is produced by rst moving thepusnbuttonswitcnlcmclomcimntpos- W tion and then moving contact deviceJl to closed circuit position which will energize relay I through a circuit which comprises conductor Y. of the source of alternating current. conductor 33, contact device M, conductor ll, contact device 0, conductor u, the contacts of limit switch CC, conductor Il, the coil of relay I and conductors Il and l2 to the conductor Z of the source of oalternating current. At the same time relayslandlwillbeenergiaedtoclosetheircontact elements. and 33 to place the maximum load1monthegenerator3laAtthistimerelays K21|.nd 3 will be deenergiled, since the contact element ofrelaylwillbemuvedtotheopen circuit position, and the maximum resistancewillbeconnectedintherotorcircuit ofthe'motor I l.l Under these conditions, the speedI tomue characteristic of the motor represented .by the curveEofPig.5willbepmducedandtheknit ting machine'will run at a speed of approximately 8 courses per minute.

To produce the high speed necessary for knittingthewelt.thepushbuttonswitch3Cwillbe moved to the open circuit position and the push button switch F will be moved to the closed circuit position. This will energize relay 2 to conf nect the minimum of resistance in, or short circuit, the rotor circuit of motor Il, to produce the speed torque characteristic of motor Il represented by curve A of Fig. 5.

When it is necessary to turn the welt, the welt turning speed of 8 coursesA per minute is produced by the closing of the contact elements of the limit switch W by the protuberances M on the belt I of the control device I8 which will energize relays l and 5 and will cause relay 2 to be deenergized through the opening of the contact element 60 of relay l. Under these conditions, the maximum of resistancejwill be connected in the rotor circuit oi the motor Il and the maximum load will be placed upon the motor I by connecting the minimum resistance in circuit with the generator Il.

After the control device Il permits the limit switch W to move its contacts to open circuit position, the conditions which existed before the contacts of limit switch W were closed will duced by the opening of the contact elements of limit switch N by the control device Il at the proper points in the knitting cycle. It will be seen that when the contact elements of limit switch N are open, relays 2 and 3 will be deenergized and only relay 4 will be energized. This will produce the speed torque characteristic of motor 1 0 represented byn the curve E oi Fig. 5, and will produce a knitting speed of approximately 30 courses per minute.

The slow knitting speed maybe produced automatically by the limit switch SL controlled by the protuberances M on belt 98 of the control device 98 or by moving the switching device F to the open circuit position'. It will be noted that the moving of either switching device F to open circuit position or the opening of the contact elements of limit switch SL will open the circuitof relay 2 to close the circuit through relay 3 by moving the contact element ll of relay 2 to closed circuit position. This operation will cause the contact element 2l of relay 3`to close to connect only a part of the resistances I6, 2li and 2l in the rotor circuit of the motor Il and the speed torque characteristic range produced thereby is represented by the range of speed torque characteristic between the cru'ves B and C of Fig. 5, and will produce knitting speeds of between 40 and 60 courses per minute.

It will be apparent that the amount of resistance connected in the output circuit of the generator 30 may be varied by the movable resistor contact which is connected in circuitA by the contact element lt of relay i of the devices of both Figs. 1 and 2, and in this waynarrowing speed torque characteristics other than that represented by the curve D of Fig. 5 may be produced Just as the variation oi the value oi' resistances I4, Il and 22 and Il, 2l and 2l may produce different speed torque characteristics within the range bounded by the linesA, B and B, C.

It is understood that the invention herein disclosed is not.limited in itsapplicationto a knitting but may be applied to'ny m2#- chine where a large range of speeds is necessary :while maintaining a substantiaiLv constant torque on a driven machine. It will be seen that we have provided a system which may be governed automatically or manually for controlling the speed-torque characteristics of a motor so that a high torque may be maintained tion. It is to be understood, however, that the invention is not limited to the precise construc- Ations shown and described but is capable of modiiication by one skilled in the art, the embodiments herein being merely illustrative of the principle of our invention.

We claim as our invention:

1. A speed control system for a knitting machine, comprising, an induction motor for driving the machine, and means for causing said motor to run at a relatively low speed while starting the machine while maintaining a relatively high starting torque comprising a series generator driven by said motor and manually controlled means for placing'a selectively variable load uponsaid generator.

2. In combination, aKV machine which requires a differentv speed for each of a plurality of operations throughout the knitting cycle, an induction motor for driving said machine, a ilrst speed control means ior causing said motor to operate at the lower speeds within the required speed range comprising a series generator driven by said motor and means for varying the load on said generator, a second speed control means i'or causing said motor to operate at the higher speeds within the required speed range comprising means controlled in accordance with the operation of the knitting machine for varying the resistance of the rotor circuit of the motor, and means for actuating said iirst and second speed control means in accordance with a predetermined sequence oi operation during the knitting cycle.

3. In combination, a machine which requires a plurality of diil'erent speeds throughout the knitting cycle, an induction motorior driving said machine, speed y control means for causing said m'otor to operate at the higher `speeds within the required speed range comprising means for varying the resistance oi the rotor circuit of the motor, speed control means for causing said motor to operate at the lower speeds of the required speed range comprising a generator driven by said motor and means for varying the load on said generator, manually controlled means for actuating said speed control means to produce certain of the required motor speeds and other `actuating means for said speed control means controlled by the knitting machine for producing other of the required speeds in a predetermined sequence.

4. A drive system for a machine which re-V quires a wide speed range while maintaining a high torque, comprising, a wound rotor induction motor iordriving the machine, means for varying the rotor circuit resistance to vary the motor speed in the upper part of the speed range, and meansiorvaryingtheloadonthemotortovary themotorspeedinthelowerpartoithespeedmae. comprisinga series generator driven by said motor and means for selectively varying the load on the generator in accordance with the desired-motor speed in the lower part of the speed rans Jr. Y

5. A drive system for a variable speed machine, comprising a wound rotor induction motor for drivingl the machine, means for varying the resistance of the rotor circuit to vary the motor speed in the upper partof the speed range and means for varying the motor speed in the lower part of the speed range, comprising a dynamoelectric machine driven by said motor and means for selectively chanin the load on said dynamoelectric machine in accordance with Vthe desired i motor speed in the'lower part of the speed range.

6. In combination, a hosiery knitting machine, a wound rotor induction mot'or connected to drive said machine, a plurality of ce elements. relay means for connecting various ones of said resistance elements in the rotor circuit of said motor.; a generator driven by said motor, relay means for connecting various ones of said resistance elements in the output circuit of said generator, manually operative means for selectivelyenergizing certain ot. said relays to cause said motor to operate at the desired speeds, and

means automatically operated in a predetermined sequence byv and in accordance with the operation o! said knitting machine for selectively energizing certain of said relays to cause said motor Y to operate at predetermined speeds in a predetermined sequence during the knitting cycle.

7. In combination, a hosiery knitting machine, a wound rotor induction motor connected to drive said machine, a plurality oi resistance elements, relaymeansiorconnectingvariousonesofsaid resistance elements in the rotor circuit oi' said motor, a generator driven by said motor, relay means for connecting various ones ot said resistance elements in the output circuit of said generator, manually operative means for selectively gcertainofsaidrelaystocause said motor to operate at the desired speeds, and means automatically operated in a predetermined sequence by and in accordance with the operation o! said knitting machine for selectively energlzlngcertainoi saidrelaystocausesaidmotor to operate at predetermined speeds in a predetermined sequence-during the knitting cycle, and limit switch means for deener'gizing said motor at predetermined phases of the knitting cycle.

8. In combination, a hosiery knitting machine, a wound rotor induction motor for driving said machine, a plurality oi' resistance elements, relay means ior connecting various ones of said resistance elements in the rotor circuit of said motor to thereby vary the speed of the motor in the upper part of the desired speed range for the knitting machine, a generator driven by said motor and relay means for connecting various .ones of saidoresistance elements in the output circuit of said generator to thereby vary the speed ci said motor in the lower part of the desired speed range for the knitting machine, manual means for selectively said relays to thereby cause said .motor to operate at the desired speed, and a plurality of limit switches actuated in a predetermined sequence by and `il'i accordance with the operation of said knitting with said relays to thereby vary the lmotor in a predetermined sequence during the knitting cycle. y

-9.A drive system for a variablespeed machine, comprising, a wound rotor induction motor /ior driving the machine, means for varying the resistance of the rotor circuit to vary the motor speed in the upper part of the speed range, and meansfor selectively varying the motor speed while maintaining a relatively high motor torque in the lower part of the speed range, comprising, a variable auxiliary loadl ior the motor and means for selectively varying said auxiliary load in accordance with the, desired speed changes in the lower part of the speed range.

10. A control system for a hosiery knitting machine, comprising, an induction motor for driving the machine, and means for causing said motor to run at a relatively low speed while maintaining a relatively high motor torque while starting the machine comprising manually controlled means for placing' an auxiliary load upon said motor, and means i'or selectively varying said auxiliary load in accordance with the desired -motor speed in the lower part oi the motor speed range.

l1. In combination, a hosiery knitting machine which requires a dlflerent speed for eachof several operations throughout the knitting cycle, an induction motor for driving said machine, speed-control means for causing said motor to run at the lower speeds within the required speed range comprising an auxiliary loading means forV the motor,\speed control means for calming said motor to run at the higher speeds within the required speed range comprising means for varying the resistance of the rotor circuit of said motor, and means controlledby the knitting machine for actuating said speed control means in accordance with a predetermined sequence oi operation of the knitting ma'- chine during the knitting cycle. v

12. In combination. a hosiery knitting machine which requires a plurality of diierent speeds throughout the knitting cycle, an induction motor for driving said machine, speed control means for causing said motor to run at the higher speeds within the required speed range comprising vmeans for varying the resistance of the rotor circuit of the motor, speed control means for causing said motor to run at the lower speeds of the required speed range comprising an auxiliary adjustable loading means for said motor, manually controlled means for actuating said speed control means to produce some'ot the required motor speeds and otheractuating means for said speed .control means controlled by the knitting machine for producing other of the required speeds in a predetermined' sequence.

13. In combination, a. knitting machine which requires a,l plurality of diilerent speeds throughout -the knitting cy'cle, a Wound rotor induction motorv for driving said machine, speed control means for causing said motor to run at the higher speeds within the required speed range comprising means for inserting various amounts of resistance in the rotor circuit of the motor, speed control means for causing said motor .to run at the lower speeds of the required speed range comprising an adjustable auxiliary loading means for said;motor, manually controlled means for actuating certain oi.' said speed control means to produce certain of the required speeds, means including a limit switch controlled by the knitting machine for actuating other of said speed control means to produce another of said required speedsat predetermined intervals.

14. In combination, a knitting machine which requires a plurality of different speeds throughout the knitting cycle, a wound rotor vinduction motor for driving said machine, speed control means for causing said motor to operate at the higher speeds within the required speed range 'comprising means for inserting various `amounts of resistance in the rotor circuit of the motor, speed control means for causing said motor to run at the lower speeds of the required speed l0 range comprising a. generator driven by said motormdmeansforvarylnxthelosdonsddlmeratorrmmuslly controlled means for whntinx

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