Tellerman, Edward M. (East Rockaway, NY)
Tellerman, Nathan J. (Hewlett Harbor, NY)
Handelsman, Robert L. (Commack, NY)

04/734742

03/23/1971

06/05/1968

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Stop-Motion Devices Corporation (Plainview, NY)

318/6

66/157, 200/61.140, 57/80

D04B35/10; D04B35/00; B65H59/38

318/6,40,436 200/61.13,61.14 57/80 66/157

3343008

Filament tension monitoring devices

September 1967

Banchroft

Dobeck, Benjamin

We claim

1. Yarn tension control means for controlling the tension in yarn travelling from a source of supply to a work station on a knitting machine comprising:

2. Yarn tension control means in accordance with claim 1, wherein said electrically operated means comprises an electric motor operatively connected to said reel, and motor control circuitry for selectively adjusting the direction and magnitude of rotational force applied to said reel for correspondingly selectively adjusting the direction and magnitude of lineal force applied to the free end of said tape and to said yarn sensing means.

3. Yarn tension control means in accordance with claim 2, wherein there is provided a contact member adapted to be normally supported by the travelling yarn portion which is in engagement with the yarn sensing means when the latter is in said normal operating position thereof, said contact member being automatically movable to a stop motion circuit completing position thereof when said yarn sensing means is moved to said another position thereof in response to an increase in yarn tension which overcomes the opposing force selectively applied to said yarn sensing means by said electric motor.

4. Yarn tension control means in accordance with claim 2, wherein said motor control circuitry comprises:

5. Yarn tension control means for controlling the tension in yarn travelling from a source of supply to a work station on a knitting machine comprising:

6. Yarn tension control means in accordance with claim 5, wherein said yarn sensing means comprises a pair of spaced loops through which the travelling yarn is passed and wherein said contact member includes a tongue normally supported by the portion of the travelling yarn between said loops.

7. Yarn tension control means in accordance with claim 6, wherein said contact member includes an electrical contact element automatically biased into stop motion circuit completing position when said tongue ceases being supported by said travelling yarn portion.

8. Yarn tension control means for controlling the tension in yarn travelling from a source of supply to a work station on a knitting machine comprising:

9. Yarn tension control means in accordance with claim 8, wherein said means for selectively controlling said net opposing force comprises an electric motor operatively connected to said reel. 16Yarn tension control means in accordance with claim 11, wherein there is provided motor control circuitry for selectively adjusting the direction and magnitude of rotational force applied to said reel for correspondingly selectively adjusting the direction and magnitude of linear force applied to the free

BACKGROUND OF THE INVENTION

Modern day knitting machines are usually equipped with means for automatically stopping the machine when a fault in the knitting process occurs. These means are commonly known as stop motions and are adapted to instantaneously detect knitting faults such as yarn breakage or variations in yarn tension beyond a permissible range. Such stop motions usually consist of a yarn sensing device which is in operative relation with respect to the yarn in such manner that when the yarn tension exceeds the permissible range, the sensing device will be operative to cause the completion of an electrical circuit which will in turn cause the interruption of the drive motor for the knitting machine. Examples of yarn tension control devices in existence today are shown in U.S. Pat. Nos. 2,242,875, 2,515,479 and 3,257,518, all of which are assigned to the assignee hereof. It is important and necessary to provide, in a yarn tension control device, means for adjusting the range of tension permissible in yarn before activation of the stop motion so that the device can be adapted for the wide variety of yarns which may be used in the knitting machine and the wide variety of articles which may be knitted by the machine.

The yarn tension sensing means available in stop motions in current use, as typified in the above patents, are usually associated with spring means which define a mechanical force which must be overcome by the yarn sensing device, in response to increased tension of the yarn, before the sensing means becomes operative to activate the stop motion. Thus, the permissible yarn tension range is selected by adjusting the spring force acting upon the yarn sensing device. Such mechanical means are not wholly satisfactory because the range of adjustment is limited and accurate selection of a particular tension range is not easily obtainable. Another drawback of present day yarn tension sensing means is that the spring force acting thereagainst is not a constant, being a function of any physical displacement of the spring, which displacement does take place during the limited permissible motion of the yarn tension sensing means before it becomes operative to activate the stop motion. This variation of the spring force for any particular setting thereof, will cause, during normal operation of the knitting machine, substantial physical oscillation of the yarn sensing device due to variations in yarn tension which do not exceed the permissible maximum. A further drawback of conventional yarn tension sensing means is that they are usually fixedly positioned at locations on the knitting machine which are not easily accessible.

SUMMARY OF THE INVENTION

In accordance with the present invention, the yarn sensing device, which comprises a pair of eyes or loops through which the yarn is passed, is carried at the end of a tape which is wound onto a roller. In accordance with such arrangement, increased tension on the yarn will cause the end of the tape to be pulled downwardly, unwinding the roller. In the normal operating position of the tape, and of the yarn carrying loops, the yarn portion between the loops supports a fly wire or tongue which is pivotally mounted so that when it is unsupported, it is gravitationally biased to a position in which it is operative by means of a contact finger to close a contact for completing an electrical circuit which in turn is operative to activate the stop motion. During normal operation of the knitting apparatus, the yarn portion between the loops supports the tongue to prevent the latter from completing the stop motion activating electrical circuit.

When the tension of the yarn passing through the loops is increased beyond the permissible range, the yarn will cause downward movement of the loops, possible by the unwinding of the tape, and thus remove the yarn portion between the loops from the position in which it supports the tongue, in turn permitting the latter to move under gravitational force and activate the stop motion. Should the yarn run out as a result of a break, the tongue will similarly drop down under the action of gravity to activate the stop motion.

The tape carrying roller is driven by a motor provided with control means so that said motor can be operated to move the tape either downwardly for gaining easy access to the yarn sensing device, or upwardly so that the yarn sensing device can be restored to its normal operating condition. In the normal operating position of the tape, the motor control means can be adjusted so as to apply to the tape an upward force which would have to be overcome by increased yarn tension before the yarn sensing device can move downwardly in order to activate the stop motion. This static force imparted to the tape can be varied electrically by controlling the amount of current flow through the motor and in this manner the permissible tension on the yarn can be adjusted accurately and within a far greater range than is available by the spring means used in connection with conventional yarn sensing devices as aforedescribed.

Furthermore, the upward force applied to the tape through the motor remains constant as it is not a function of the movement of the tape, thus preventing the occurrence of undesirable oscillations and fluctuations in the yarn sensing device during the operation of the machine. Because adjustment of tension range is a matter of electrical motor control, the latter can be located in an easily accessible location though the normal location of the yarn sensing device is not easily accessible.

BRIEF DESCRIPTION OF THE DRAWINGS.

FIG 1 is a schematic representation of the yarn tension control device in accordance with the invention;

FIG. 2 is a circuit diagram of the control circuitry for the yarn tension control device in accordance with the invention;

FIG. 3 is a front elevation view of the preferred embodiment in accordance with the invention, with part of the front wall removed for purposes of illustration;

FIG. 4 is a right side view thereof;

FIG. 5 is a top view thereof, with the top wall removed, for purposes of illustration;

FIG. 6 is a section taken along line 6-6 of FIG. 3;

FIG. 7 is a section taken along line 7-7 of FIG. 3;

FIG. 8 is a view similar to FIG. 7 showing the yarn tension control device in condition for activating the stop motion;

FIG. 9 is a perspective view, on an enlarged scale, showing the manner in which the yarn sensing member is attached to the end of the tape; and

FIG. 10 is a view similar to FIG. 8 showing a modified embodiment of the invention

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the schematic representation in FIG. 1, there is shown a roller 10 on which there is wound a tape 12, the end of which is provided with a yarn sensing member 14 having a pair of laterally offset spaced loops 16 through which is passed yarn 18 as it proceeds from the supply thereof to the knitting machine. During normal operation of the yarn tension control device, the tape is in its uppermost position as shown by the full lines in FIG. 1, which uppermost position is determined by the engagement of stop means 20 on the tape and roller housing 22. A wire 24 is pivotally mounted as at 26 to housing 22 and is supported, during normal operation, between loops 16 by the yarn 18 passing therethrough. During such normal operation, portion 28 of wire 24, on the opposite side of pivot 26, is out of engagement with electrical contact 30.

In the normal operating position of the tape as shown in FIG. 1, it will be evident that downward movement of the tape, in response to increased tension in the yarn, will take place when the downward force applied by the yarn overcomes the upward force acting on the tape. Such upward force consists of the normal frictional force in roller 10 and all elements connected thereto required to be overcome to initiate counterclockwise movement of roller 10 (viewing FIG. 1) plus any additional static force imparted to roller 10 by motor 32 which is operatively connected thereto. BY means of motor control 34 as will more fully be described hereafter with reference to FIG. 2, the net upward force applied to the tape can be accurately selected within a wide range to meet the desired requirements of the particular yarn.

The operation of the yarn tension control device is as follows: The desired yarn tension beyond which the stop motion is intended to be activated is adjusted through motor control 34, providing the requisite net static upward force on the tape. When the yarn tension exceeds the permissible range, the yarn passing though loop 16 pulls the latter down unwinding tape 12, until the yarn between loop 16 is no longer in the path of movement of wire 24, as shown by the dashed lines in FIG. 1, causing wire 24 to pivot under the action of gravity until portion 28 thereof engages contact 30 to complete a circuit through stop motion 36 which, as previously explained, automatically interrupts the drive motor for the knitting machine. A lamp 38 may be provided in series with contact 30 so that the latter will be lit upon activation of the stop motion to provide an immediate visual signal of the location of the activated yarn tension control device.

It will also be noted from FIG. 1 that upon breakage of yarn 18, the yarn will cease supporting wire 24 and thus also activate the stop motion for interrupting the knitting machine drive motor.

Tape 12 is of sufficient length os that, if desired, roller 10 can be unwound under the control of motor 32 to lower yarn engaging loops 16 to a level where these are easily accessible for inspection, rethreading, or any other purpose, eliminating the inconvenience usually caused by the inaccessibility of the yarn sensing device. To restore the tape and yarn sensing device to its operating position, the tape can easily be wound onto roller 10 under control of motor 32 with maximum speed and convenience.

Motor 32 is thus seen as performing the function of lowering and raising the tape as well as imparting to the tape a selected net upward force for adjusting the permissible yarn tension. The manner in which the motor is controlled will now be described with reference to the circuit diagram of motor control 34 as shown in FIG. 2.

Referring now to FIG. 2, there is shown motor 32 and the manner in which it is controlled by the circuitry in motor control 34.

Motor M is a conventional DC motor which can rotate in either direction depending on the direction of current flow therethrough. As shown in FIG. 2, current flow downwardly through motor M as shown by arrow D will cause the motor to rotate so as to unwind tape 12 (moving the tape downwardly). Conversely, current flow upwardly through the motor in FIG. 2 as shown by arrow U will cause the motor to rotate so as to wind up tape 12 (moving the tape upwardly). A relay 40 controls a pair of switches 42 and 44 as follows: When relay 40 is unenergized, switches 42 and 44 are in the position as shown in FIG. 2, in engagement with contacts 46 and 48, respectively. When relay 40 is energized, switches 42 and 44 are in engagement with contacts 50 and 52, respectively. A toggle switch 54 operates switch blades 56 and 58 so that they are movable from the position as shown in FIG. 2 in which they engage contacts 60 and 62, respectively, to their other position in which they are in engagement with contact 64 and dummy contact 66, respectively. Resistors 68, 70 and 72 are conventionally adjustable resistors while resistor 74 cooperates with movable contact arm 76. Pushbuttons 78 and 80 are normally biased in the position shown in FIG. 2 in which they engage contact 82 and dummy contact 84, respectively, and are independently manually movable into engagement with contacts 86 and 88, respectively. A battery 90 is provided for supplying power to motor M and the control circuit therefor. A pair of diodes 92 and 94 perform their conventional function of permitting current flow in only one direction, as shown.

As previously stated, motor M performs the function of (1) moving the tape downwardly, (2) moving the tape upwardly, and (3) applying a static force on the tape in order to adjust the permissible tension on the yarn. The manner in which these three functions are performed by the motor, through motor control 34, will be described.

DOWNWARD MOVEMENT OF THE TAPE

Such downward movement is accomplished by depressing pushbutton 78, the down push button, so that it is in engagement with contact 86. In such position of pushbutton 78, it will be evident that there is no current flow through relay 40, regardless of the position of toggle switch 54, because both contacts 82 and 88 are open, whereby switches 42 and 44 remain in the position as shown in FIG. 2, namely, in engagement with contacts 46 and 48, respectively. Accordingly, when pushbutton 78 is depressed, there is current flow from the positive terminal of battery 90, through contact 46, switch 42, down through motor M, switch 44, contact 48, terminal 96, variable resistor 70, contact 86, pushbutton 78 and back to the negative terminal of battery 90. Such complete current flow path causes motor M to turn in a direction to unwind the tape for so long as pushbutton 78 is depressed Variable resistor 70 controls the amount of current flow through motor 32 while pushbutton 78 is depressed, to in turn control the speed at which the tape is unwound.

UPWARD MOVEMENT OF THE TAPE.

Such upward movement is obtained by depressing pushbutton 80 so that it engages contact 88. The depression of pushbutton 80 completes the following circuit: Positive terminal of battery 90, terminal 98, terminal 100, relay 40, terminal 102, diode 94, contact 88, pushbutton 80, and back to the negative terminal of battery 90. This circuit path energizes relay 40 which in turn causes switches 42 and 44 to engate contacts 50 and 52, respectively, and in turn completing the following circuit: Positive terminal of battery 90, terminal 98, terminal 100, contact 52, switch 44, up through motor M, switch 42, contact 50, terminal 96, terminal 104, variable resistor 72, diode 92, terminal 106, contact 88, pushbutton 80 and back to the negative terminal of battery 90. Such complete path permits current flow through motor M in a direction to move the tape upwardly with resistor 72 being adjustable to control the speed of the movement of the tape.

APPLICATION OF STATIC VERTICAL FORCE ON THE TAPE

The previous description has indicated that, in the absence of any static force applied by the motor to the tape, there exists an upward force on the tape (due to the friction of the roller, etc.) which must be overcome before the tape can move downwardly in response to increased yarn tension. This force can be increased or decreased by the motor. Insofar are increasing that force is concerned, it will be evident that such can be done by permitting current flow through the motor in a direction to wind up the tape, providing a static force on the tape since in the normal operating position thereof, it is at its uppermost position where it is prevented by stop 20 from moving further upwardly. Thus if, for example, the normal frictional forces to be overcome amount to 20 grams, such can be increased by any desired amount.

Assuming again that the static frictional force on the tape to be overcome is 20 grams, it will be evident that such force can be decreased by permitting current flow through the motor in a direction to unwind the tape but only sufficiently to provide a downward force less than 20 grams, probably not greater than 15 grams. If for example sufficient current were permitted to flow through motor M to define a downward force on the tape of 10 grams, it would be insufficient to cause downward movement of the tape but it would reduce by 10 grams the amount of force to be overcome by the increased yarn tension to cause downward movement of the tape and activation of the stop motion.

Adjustment of the force on the tape to increase the same is obtained by placing the toggle switch in the position as shown in FIG. 2 wherein blades 56 and 58 are in engagement with contacts 60 and 62, respectively. In such position, there is current flow through the following path: Battery 90, terminal 98, terminal 100, relay 40, terminal 102, switch blade 58, contact 62, pushbutton 78 (in its normally undepressed position) and back to the battery. This completed path energizes relay 40 causing switches 42 and 44 thereof to engage contacts 50 and 52, respectively, in turn permitting current flow through the motor as follows: Battery 90, terminal 100, contact 52, switch 44, up through motor M, switch 42, contact 50, terminal 96, terminal 108, switch blade 56, contact 60, resistor 74, contact arm 76, terminal 110 and back to the battery. This results in current flow through the motor in a direction to move the tape upwardly. Since the tape, during the normal operating position thereof is in its uppermost position as defined by the engagement of stop 20 with housing 22, the current flow through motor 32 provides a static additional upward force on the tape with the magnitude of such force being adjustable by movable contact arm 76. As contact arm 76 is moved upwardly, viewing FIG. 2, a greater portion of resistor 74 is in the motor circuit to decrease current flow therethrough and decrease the amount of force provided thereby.

Adjustment of the force on the tape to decrease the same is obtained by placing the toggle switch in position in which blades 56 and 58 thereof are in engagement with contact 64 and dummy contact 66 respectively. In such position of toggle switch 54, there is no current flow through relay 40 whereby switches 42 and 44 thereof remain in engagement with contacts 46 and 48, respectively. In such condition, there is current flow as follows: Battery 90, terminal 98, contact 46, switch 42, down through motor M, switch 44, contact 48, terminal 96, terminal 108, switch blade 56, contact 64, variable resistor 68, resistor 74, movable contact arm 76 terminal 110 and back to the battery. This circuit path provides current flow through the motor in a direction to move the tape downwardly. The amount of force provided by the motor is adjusted by movable arm 76 and in this connection it should be noted that the amount of current flow through motor M should be such as to provide a downward force on the tape less than the normal frictional force acting up on the tape, in order to prevent the tape from physically moving downwardly. Variable resistor 68, in series with the motor for 68, adjustment function thereof, limits current flow through the motor in order to prevent over running of the tape downwardly during the adjustment function.

From the above it is seen that the circuitry in motor control 34 permits motor 32 to perform all of its intended functions, namely, (1) lowering the tape to gain convenient access to the yarn sensing device attached at the end of the tape, (2) raising the tape to restore it to its normal uppermost operating position, and (3) providing a static vertical force on the tape both upwardly and downwardly in order to provide accurate adjustment of the permissible tension for a substantial range.

Referring now to FIGS. 3 to 8, there is shown a specific embodiment of the yarn tension control device 112 in accordance with the invention. Control device 112 comprising a generally rectangular housing 114 made up of upper and lower sections 116 and 118 secured together by means of bolts 120. Housing 114 is provided with a toggle clamp 122 for securement to the channel member of a current supplying stop motion head used on a knitting machine such as shown in U.S. Pat. No. 3,001,389, assigned to the assignee hereof. As described in said U.S. Pat. No. 3,001,389, the attachment of a clamp similar to toggle clamp 122 onto the channel member of the current supplying stop motion head described therein, automatically supplies current to contact 124 on said toggle clamp.

Housing 114 includes roller 126 journaled in a roller casing 127 therefor. Roller 126 is wound thereon a tape 128 which exists from the bottom wall 129 of the housing through a slit 130. The end of the tape is provided with a yarn sensing member 131 consisting of an inverted generally U-shaped wire member having a base 132 and a pair of curved arms 133, terminating in a pair of spaced pigtail-type loops 134 laterally offset from the plane of the tape. As best seen in FIG. 9, the end of the tape is preferably secured between a backing plate 135 and yarn sensing member 131 for better weighting and balancing of the lower end of the tape.

A DC motor 136, mounted in housing 114 by means of bracket 137, is adapted to drive roller 126 through the intermediary of pinion 140 mounted on the motor shaft, and gear 142 mounted on roller shaft 138. Power for motor 136 is supplied by means of motor control 34 (previously described in connection with FIG. 2) through which the motor can be operated to wind the tape onto roller 126, to unwind such roller, or to apply a static force to tape 128.

For normal operation of yarn tension control device 112, the yarn sensing member 131 is in its uppermost position defined by the physical engagement thereof with housing 114 as best shown in FIGS. 3, 6 and 7. Yarn 144, whose tension is to be controlled, is passed through loops 134 on its way to the knitting machine. In view of the pigtail construction of the loops, the yarn can be threaded therethrough without requiring a break in the yarn. A tongue 146 is pivotally mounted as at 148 and projects outwardly of bottom wall 129, said tongue being provided with a contact finger 152 extending from pivot 148 inwardly of the housing. Contact finger 152 is electrically grounded to the housing through pivot 148. A conductor strip 154 is mounted on terminal 156 insulated from the housing. During normal operation of the knitting machine, tongue 146 is supported by yarn 144 between loops 134 and in such condition, there is no contact between grounded contact finger 152 and conductor strip 154. In the event that the tension on yarn 144 increases to an extent sufficient to provide a downward force on the tape which overcomes the upward force thereon as adjusted by the motor control, the yarn will pull yarn sensing member 131 downwardly, thereby removing the support for tongue 146 and thus freeing the same. In such unsupported free condition, the force of gravity causes tongue 146 to pivot counterclockwise forcing contact finger 152 into engagement with conductor strip 154, thus grounding it. Conductor strip 154 is in turn connected at terminal 156 to wiring 158 which is in series with lamp 160. Lamp 160 is in turn electrically conducting to conducting element 162, which terminates in a conducting surface 163 positioned so that when housing 114 is fully assembled, it comes into electrical contact with conducting element 164 which is in electrical contact with element 124 on the clamp 122. Accordingly, it will be seen that the engagement of contact finger 152 with conductor strip 154 completes an electrical path from contact element 124 on the clamp to ground. It will be understood that the completion of such circuit by means of clamp 122 permits current flow for lighting lamp 160 and activates the stop motion mechanism to immediately interrupt the drive of the knitting machine. Thus, it is clear that the increase in yarn tension beyond the permissible range, adjusted by motor control 34 as described in connection with FIG. 2, causes the automatic completion of circuitry for activating the stop motion and lighting signal light 160. It will also be noted that in the event that there is a break in the yarn, the latter will run out and also terminate its support of tongue 146 to, in turn, complete the circuitry for activating the stop motion.

While the embodiment as shown in FIG. 3 through 8 shows roller 126 to be driven by the motor through the intermediary of a gear train, it will be evident that a direct drive or a capstan drive could be used as well. It will also be noted that, as shown in the dotted lines in FIG. 3, the yarn sensing member 131 can be lowered by means of motor 136 to an easily accessible position for rethreading or for making any other adjustments which may be desired. Following such lowering of the tape and sensing member 131 for the intended purposes, it is a simple matter of restoring the yarn sensing member to its operating position by merely pushing the up button on the motor control and maintaining it depressed until yarn sensing member 131 reaches its uppermost position, when in engagement with the housing 114, which uppermost position is the normal operating position for the yarn control device. All other adjustments, particularly as to the desired tension setting for the yarn are made through the motor control 34 which can be located where most convenient from the operator's point of view. While the weight of the yarn sensing device 131 is sufficient to provide steady downward movement thereof when the down button is depressed, without undue back and forth oscillations of the tape, it may be found preferable to utilize any conventional means for guiding the vertical movement of the yarn sensing device 131 or of the tape. For example, and as shown in FIG. 10, backing plate 135 may be provided with rearwardly extending apertured flanges 165 for receiving therethrough guide rod 166 downwardly extending from bottom wall 129 of the housing.

It will be noted that the various resistances forming part of motor control 34 are selected so as to provide a highly sensitive range of adjustment for the yarn tension control, and the motor control is provided with conventional calibrated members associated with all the variable resistors for providing the requisite visual indication.

In view of the fact that the yarn sensing element is attached to a wound tape, the yarn sensing element is displaceable for a substantial range of movement while retaining the yarn through the loops, making subsequent rethreading unnecessary, in contrast with conventional yarn sensing elements whose displacement is severely limited, resulting in loss of yarn retention.

While we have herein shown and described the preferred embodiments of our invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that in the illustrated embodiments certain changes in the details of construction and in the form and arrangement of parts may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.