US3694722A

US3694722A - Speed reducing apparatus for a cloth spreading machine

Info

Publication number: US3694722A
Application number: US125470A
Authority: US
Inventors: Robert G Reed
Original assignee: Cutters Machine Co Inc
Current assignee: Saber Industries Inc
Priority date: 1971-03-18
Filing date: 1971-03-18
Publication date: 1972-09-26
Anticipated expiration: 1989-09-26
Also published as: DE2204409A1; CA957049A; JPS5733259B1; GB1361687A

Abstract

An electrically driven and controlled cloth spreading machine including means for controlling the high and low speeds of the machine, and for dynamically braking the machine from a high speed to a pre-set low speed upon signal.

Description

ii I

United States Patent Reed [4 Sept. 26, 1972 [5 SPEED REDUCING APPARATUS FOR A [56] References Cited- CLOTH SPREADING MACHINE UNITED STATES PATENTS [721 Invent Reed Nashville, Tenn. 2,760,135 8/1956 Hillyer ..3l8/368 x Assignee; Cutters Machine Company Inc Martin X Nashville, Tenn. Primary Examiner-Bernard A. Gilheany [22] 'Flled: March 1971 Assistant Examiner W. E. Duncanson, Jr. [21] App} 125,470 Attorney-Harrington A. Lac'key I s 57 ABSTRACT s [52] US. Cl ..3l8/368, 318/375 [51] Int. Cl. ..H02r 3/12 electfilcally f and controlleqcloth f m [58] Field of Search ..318/364-36 6, 368, machme mcludmg meaffs for trolling the high and e low speeds of the machine, and for dynamically brakmg the machine from a high speed to a pre-set low speed upon signal.

7 Cleims, 2 Drawing Figures 3 A A LOW VOLTAGE A.B.D Ac "I I SUPPLY 1 AC AC 2 a9 S 9 Ac w X I t 2 DYNAMIC BRAKE 2 e 75 TIME- 74%; D DELAY V u it 76 CONTROL Z8 L 4re scnumoc: 69/ L 4 76 S MOTOR SPEED CONTROL i M AQE'AEE REVERSING '79, CONTROL 4] 79- v I l 1 CLOTH D H FEED 58 X a l STOP- 62 is; W 66 START m 1 L SPEED CONTROL 57 l .l. i

so r. 1i Y Z; V i i, v 69 L DRIVE-STOP 9 CONTROL 0 4 'r' i i 4? l LO 50 -51 men ow SPEED 49 DYNAMIC BRAKE TRIGGER "1mm m2 3.694.722

SHEET 1 0F 2 REV POWER DRIVE INVENTQ 3 [2055/87 6. 550

TORNEY SPEED REDUCING APPARATUS FOR A CLOTH SPREADING MACHINE BACKGROUND OF THE INVENTION each reversing station for cooperative engagement with the catcher mechanism to form folds in the ends of the layers of cloth. However, in order to minimize damage to the machine and cloth, and jerking and irregular folding of the cloth at each reversing station, various electrical switch controls have been adopted in order to reduce the speed of the machine just prior to its cooperation with the catcher mechanism. It is also known to resume the high speed of the machine as soon as possible after it has reversed its movement and formed the fold in the layer of cloth.

In the co-pending application of Robert W. Benson et al., Ser. No. 857,509, filed Sept. 12, 1969, for ELECTRICALLY CONTROLLED CLOTH SPREADING MACHINE, a dynamic braking circuit is employed with the electrical drive motor in order to decelerate the machine from its high speed to its preset low speed. However, the dynamic braking circuit is energized for a pre-set time by an electrical time-delay circuit. It has been found that where the machine is moving at high speeds, other than the pre-set high speed, the machine will not necessarily move at its preset low speed at the termination of the energization of the dynamic braking circuit. For example, if, for some reason the machine has been travelling at substantially less than high speed when the dynamic braking circuit is energized,then when the pre-determined time period of energization of the braking circuit is terminated, the machine may come to a full stop, or a slow speed less than the pre-set low speed. Then, when the speed control over the electrical drive resumes, the machine will re-start and accelerate until it attains the pre-set low speed. Thus, time is wasted, rather than saved, in decelerating the machine from its high speed to its low speed, preparatory to cooperating with the catcher mechanism.

SUMMARY OF THE INVENTION It is therefore an object of this invention to overcome the above enumerated disadvantages by providing an electrically driven cloth spreading machine, incorporating a dynamic braking circuit, which will rapidly decelerate from high speed to a pre-set low speed, regardless of the time required for deceleration.

Another object of this invention is to provide a speed reducing apparatus for an electrically driven cloth spreading machine including a dynamic braking circuit, in which, upon signal, the dynamic braking circuit is energized and the high speed control circuit is simultaneously de-energized. As soon as the speed of the machine has been reduced to a pre-set low speed, the dynamic braking circuit is immediately de-energized and the low speed control circuit is simultaneously energized.

Accordingly, in the speed reducing apparatus of this invention, the dynamic braking effect will immediately be deactuated as soon as low speed is attained, and completely independently of the time required to decelerate the machine from any high speed to its preset low speed.

The speed reducing apparatus of this invention includes an electrical motor drive, a motor speed control circuit, a dynamic braking circuit, a low-speed switch and a trigger circuit. When the low-speed switch is tripped by a tripping mechanism mounted at a predetermined distance from the catcher mechanism or reversing station, the trigger circuit is conditioned to energize the dynamic braking circuit and simultaneously de-energize the motor speed control and the motor. A fixed voltage is impressed upon the dynamic braking circuit which corresponds to the preset low speed value and is opposite in direction to the back EMF of the motor. Thus, as soon as the back EMF has been reduced to a value equal and opposite to the applied voltage on the dynamic braking circuit, the dynamic braking circuit is de-energized and simultaneously the motor speed control circuit is re-ener'gized to drive the motor at the preset low speed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a cloth spreading machine, made in accordance with this invention, adjacent a catcher mechanism at one end of the travel of the machine; and

FIG. 2 is a schematic circuit diagram of the electrical drive and control system for the machine.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to the drawings, FIG. 1 discloses a cloth spreading machine 10 made in accordance with this invention, including a carrier frame 11 supported by wheels 12 and 13 for longitudinal movement along a spreading table 14. A cloth supply roll 15 is supported for free rotary movement upon standards 16 mounted upon the frame 11 for unwinding and feeding a web of cloth 17. In the machine 10, the web 17 is threaded through an edge control device 18, beneath a pivotally mounted cloth tension rod 19, and then over a driven top feed roll 20. The web 17 then depends through a cloth spreader frame or unit 21, having tuck blades or spreader blades, not shown, for spreading the cloth web 17 in layers 22 upon the table 14. A catcher mechanism 24, including a catcher bar 25, is stationed upon the spreading table 14 at one end of the travel or course of the carrier frame 11 to cooperate with the spreader unit 21 in a wellknown manner to fold the end of each cloth layer 20.

An electrical motor 28 mounted on the frame 11 is operatively connected to drive the left rear wheel, not shown, which is connected by suitable chain and sprocket mechanism, not shown, to transverse drive shaft 29, which in turn is coupled through suitable sprocket and chain mechanism 30 to drive the right rear wheel 12.

The left front wheel behind the right front wheel 13, is drivingly connected to the top feed roll 20, in a wellknown manner, such as disclosed in the co-pending application of Robert W. Benson, et al., Ser. No. 857,509,

so that the top feed roll 20 is driven in the same direction independently of the front wheels 13.

Referring now to the electrical circuit diagram in FIG. 2, a low-voltage supply circuit or module 32 is connected to any suitable source of electricity, not shown, through the power switch 33, which is also disclosed upon the control panel 35 mounted on the side of the frame 1 l, as disclosed in FIG. 1.

The low voltage supply circuit 32 supplies various voltages, including B+ supply voltages, to some of the other circuits of the system, such as the motor speed control circuit 37, the stop-start control circuit 38, the time-delay control circuit 40, the reversing control circuit 41, the cloth feed control circuit 42, and the drivestop control circuit 43. The clutch and brake supply circuit 39 is supplied with A.C. current from the original power source. All of these circuits 32 and 37 43 have been disclosed in block diagram since their specific circuits are not material to this invention. As a matter of fact, most of the circuitry of the block modules or circuits 32, 37 43 can be found in the above cited co-pending application Ser. No. 857,509.

The time-delay control circuit 40 in FIG. 2 is adapted to control the machine so that it moves in lowspeed away from the catcher mechanism 24 for a pre-determined period before automatically accelerating into high speed.

The motor speed control circuit or module 37 includes high and low speed potentiometers, similar to those disclosed in the co-pending application Ser. No. 857,509, for controlling the SCR bridge circuit 45, in order to drive the electrical motor 28 at a pre-set high speed or a pre-set low speed.

Connected across the motor 28 is the dynamic braking circuit 46, which in turn is connected to and controlled by the high-low speed dynamic brake trigger circuit 47.

The trigger circuit 47 includes a pair of unidirectional, momentary, normally closed, low-speed switches 49 and 50in low-speed switch circuit 51. The low-

speed switches

49 and 50 are mounted in the bracket 52 on the side of the machine 10, as disclosed in FIG. 1, and each

switch

49 and 50 is adapted to be opened by engagement of its corresponding switch lever 53 and 54 upon the trip ramp 55 fixed to the table 14.

The low-speed switch circuit 51 is connected in series with SCR 57 and selector switch relay coil 58. The circuit 51 is also connected through capacitor 59 to the gating lead 60 for the SCR 57.

When the relay coil 58 is energized, it pulls selector switch 62 to its high-speed position, indicated in dashed lines in FIG. 2, to energize the high-speed potentiometer, not shown, within the motor speed control circuit 37. When the relay coil 58 is de-energized, selector switch 62 is moved to its solid-line, low-speed position, as indicated in FIG. 2, to energize the low-speed potentiometer, not shown, within the motor speed control circuit 37.

A lead 64 is connected at one end by contact 65 between the selector switch relay coil 58 and the SCR 57, and at its opposite end to the base of transistor 66. The collector of transistor 66 is connected to the base of transistor 67, the collector of which is connected through capacitor 68 to relay coil 69, which controls dynamic braking relay switch 70. The braking relay switch is normally open, and is adapted to be momentarily closed by the momentary energization of the relay coil 69 through capacitor 68.

The braking relay 70 is in turn connected to the gate lead 71 of SCR 72 in the dynamic braking circuit 46. The SCR 72 is connected in series with the braking resistor 73 and transistor 74, which is so designed and electrically connected within the dynamic braking circuit 46 to apply a fixed voltage upon the dynamic braking circuit 46 when energized. In this respect, a Zener diode 75 is connected in the base-collector circuit of the transistor 74, while resistor 76 is connected in the base-emitter circuit of the transistor 74.

Connected to the junction 78 between the SCR 72 and the braking resistor 73 is a signal lead 79 which communicates with the stop-start control circuit 38. When the dynamic braking circuit 46 is conducting, or energized, a current is transmitted through the signal lead 79 to the stop-start control circuit 38, and conditions the stop-start control circuit 38 to close a switch, not shown, in clamping circuit or lead 80 communicating with the motor speed control circuit 37. When the clamping lead 80 is closed, or is conducting, motor speed control circuit 37 is de-actuated or de-energized so that the SCR bridge circuit 45 is not fired, regardless of the speed setting of the selector switch 62, so that the motor 28 is not driven. In other words, the clamping circuit 80 is essentially a grounding, short, or bypass circuit, so that when the stop-start control circuit is appropriately conditioned by the current through the signal lead 79, clamping circuit 80 is clamped to ground, or closed, so that the signal generated by the motor speed control circuit 37 is grounded through the clamping circuit 80, rather than being supplied to the SCR bridge circuit 45.

One example of such a motor speed control circuit and clamping circuit is disclosed in the co-pending application of Robert W. Benson et al., for NEEDLE POSITIONER FOR A SEWING MACHINE filed on Jan. 20, 1971, under Ser. No. 107,895.

The actual switching system within the stop-start control circuit 38 for closing clamping circuit 80 in cludes a pair of transistors. One transistor is actuated by the current from signal lead 79 to transmit another signal to the second transistor in the camping circuit 80. The second transistor is turned on to render clamping circuit 80 conductive.

A similar result could be obtained by having a relay switch in clamping circuit 80 and a relay coil in signal lead 79. The current through signal lead 79 would energize the relay coil causing the relay switch to close clamping circuit 80.

In the operation of the machine 10, the frame 11 is moved, the top feed roll 20 is driven, and the spreading unit 21 cooperates with the catcher mechanism 24 in a manner similar to that disclosed in the co-pending application Ser. No. 857,509.

The machine 10 travels along the table 14 in high speed after leaving the catcher mechanism at the opposite end of the table from the catcher mechanism 24, and after the machine has travelled away from the catcher mechanism, not shown, in a predetermineed time in low speed, which is controlled by the time-delay control circuit 40. Travelling along the table 14 toward the catcher mechanism 24 in high speed, web 17 is spread over the layers 22.

When the switch actuator lever 54 engages the ramp 55, the slow-speed switch 50 opens momentarily to break the circuit 51 and thereby turn off the SCR 57 and de-energize the relay coil 58, causing the selector switch 62 to assume its solid-line, low-speed position disclosed in FIG. 2. Simultaneously, when the SCR 57 is turned off, the

transistors

66 and 67 are turned on to momentarily energized the relay coil 69, and consequently momentarily close the dynamic brake relay switch 70. I As the relay switch 70 closes, current is supplied through the gate lead 71 to turn on the SCR 72, which energizes the dynamic braking circuit 46. Simultaneously, current passes through the signal lead 79 to close the clamping circuit 80 in the stop-start control circuit 38, thereby grounding the motor speed control circuit 37 to turn off or de-energize the SCR bridge circuit 45 and thereby de-energize the drive motor 28.

As the de-energized motor 28 decelerates, it produces a corresponding back EMF through the braking resistor 73. A constant voltage of a value corresponding to the desired low speed setting of the motor speed control circuit 37 is impressed across the dynamic braking circuit 46 by the transistor 74. This voltage is opposite in direction to the back EMF of the motor 28. When the motor 28 decelerates so that it is running at the pre-set low speed, the back EMF in the braking resistor 73 is equal and opposite to the constant voltage applied to the dynamic braking circuit 46 by the transistor 74. Accordingly, current ceases to flow through the SCR 72 to automatically turn off the SCR 72. Since no current flows through the SCR 72, then no current flows through the signal line 79 to the stop-start control circuit 38 Accordingly, the clamping lead 80 is opened to re-energize' the motor speed control circuit 37, which is already set at its low speed, because of the solid-line position of the selector switch 62. Consequently, the SCR bridge circuit 45 is fired to drive the motor 28 at the constant low speed.

The machine 10 continues at its low speed into the catcher mechanism 24 where the reversing switch plunger 82 is engaged by the lug 83 to actuate the reversing switch, not shown, and energize the reversing control circuit 41 to reverse the motion of the machine 10 out of the catcher mechanism 24. The time-delay control circuit 40 maintains the machine 10 in low speed for a pre-determined period of time. At the end of the period, the speed control circuit 37 is actuated into high speed to resume the spreading operation of the machine down the table 14 in the opposite direction, that is toward the left of FIG. 1.

It will therefore be seen that an improved speedreducing apparatus has been designed, employing a dynamic braking circuit which is automatically energized upon signal to decelerate the motor28 down to, but not below, the preset low speed, at which time the dynamic braking circuit 46 is de-energized and the speed control drive mechanisms are reenergized to drive the motor at a constant low speed.

What is claimed is:

l. A speed reducing apparatus for acloth spreading machine having a frame supported for longitudinal movement over a cloth laying surface between reversing stations, a spreader unit to spread cloth in layers, and means for supplying cloth to the spreader unit, comprising: 7

a. electrically energized motor drive means for moving said frame longitudinally of said surface,

b. speed control means for selectively energizing said drive means to move said frame at a low speed, or to move said frame at a high speed substantially faster than said low speed,

c. a dynamic braking circuit connected to said motor drive means,

d. a trigger circuit including a low-speed switch, a

, speed selector switch movable between a high position and a low position, and dynamic brake switch means,

e. said selector switch communicating with said speed control means to selectively energize said drive means in high speed in high position and in low speed in low position,

f. said dynamic brake switch means, when closed, being adapted to energize said dynamic brake cir cuit,

g. said low-speed switch being adapted, when actuated, to move said selector switch to its low position and to close said dynamic brake switch means while the back EMF of said motor drive means is above a pre-set value corresponding to said low speed,

h. signal means communicating with said dynamic braking circuit and with said speed control means for actuating said speed control means to de-energize said drive means while said dynamic brake circuit is energized, and for re-actuating said speed control means to energize said drive means in said low speed while said dynamic braking circuit is deenergized,

i. trip means for actuating said low-speed switch while said frame is moving toward a reversing station.

2. The invention according to claim 1 in which said dynamic braking circuit comprises a gate switch and a braking resistor in series, and means for applying a constant voltage upon said dynamic braking circuit corresponding to said low speed and opposite in direction to said back EMF so that said gate switch turns off when said back EMF is equal to or less than said constant voltage, said dynamic brake switch means, when closed, being adapted to turn on said gate switch.

3. The invention according to claim 2 in which said means for applying a constant voltage comprises a transistor in series with said gate switch and said braking resistor, and a Zener diode in the base-collector circuit of said transistor.

4. The invention according to claim 2 in which said gate switch is an SCR.

5. The invention according to claim 2 in which said signal means comprises a signal circuit connected to said dynamic braking circuit and communicating with said motor speed control means for de-actuating said motor speed control means while said dynamic braking circuit is conducting. I

6. The invention according to claim 5 further comprising a clamping circuit adapted, when closed, to deactuatesaid speed control means and de-energize said drive means, and clamping control means for closing said clamping circuit in response to a signal impressed dynamic braking circuit.

7. The invention according to claim 1 in which said trip means is mounted a distance from said reversing reversing station.

' upon said signal circuit by the energization of said

Claims

1. A speed reducing apparatus for a cloth spreading machine having a frame supported for longitudinal movement over a cloth laying surface between reversing stations, a spreader unit to spread cloth in layers, and means for supplying cloth to the spreader unit, comprising: a. electrically energized motor drive means for moving said frame longitudinally of said surface, b. speed control means for selectively energizing said drive means to move said frame at a low speed, or to move said frame at a high speed substantially faster than said low speed, c. a dynamic braking circuit connected to said motor drive means, d. a trigger circuit including a low-speed switch, a speed selector switch movable between a high position and a low position, and dynamic brake switch means, e. said selector switch communicating with said speed control means to selectively energize said drive means in high speed in high position and in low speed in low position, f. said dynamic brake switch means, when closed, being adapted to energize said dynamic brake circuit, g. said low-speed switch being adapted, when actuated, to move said selector switch to its low position and to close said dynamic brake switch means while the back EMF of said motor drive means is above a pre-set value corresponding to said low speed, h. signal means communicating with said dynamic braking circuit and with said speed control means for actuating said speed control means to de-energize said drive means while said dynamic brake circuit is energized, and for re-actuating said speed control means to energize said drive means in said low speed while said dynamic braking circuit is de-energized, i. trip means for actuating said low-speed switch while said frame is moving toward a reversing station.

4. The invention according to claim 2 in which said gate switch is an SCR.

5. The invention according to claim 2 in which said signal means comprises a signal circuit connected to said dynamic braking circuit and communicating with said motor speed control means for de-actuating said motor speed control means while said dynamic braking circuit is conducting.

6. The invention according to claim 5 further comprising a clamping circuit adapted, when closed, to de-actuate said speed control means and de-energize said drive means, and clamping control means for closinG said clamping circuit in response to a signal impressed upon said signal circuit by the energization of said dynamic braking circuit.

7. The invention according to claim 1 in which said trip means is mounted a distance from said reversing station sufficient to permit said drive means to be energized in low speed before said frame reaches said reversing station.