US3185908A - Motor speed control apparatus for steel slitting machine - Google Patents

Description

H. B. HOLLIS May 25, 1965 MOTOR SPEED CONTROL APPARATUS FOR STEEL SLITTING MACHINE Original Filed Aug. 24, 1962 2 Sheets-Sheet 1 VENTOR. KS HOLLIS M G .W

HUBERT BROO ATTQRNEY y 25, 1965 H- B. HOLLIS 3,185,908

MOTOR SPEED CONTROL APPARATUS FOR STEEL SLITTING MACHINE Original Filed Aug. 24, 1962 2 Sheets-Sheet 2 INVENTOR. HUBERT BROOKS HOLLIS AT TOR NEY United States Patent MOTQR SPEED CONTROL APRARATUS FOR STEEL SLIT'IENG MACHINE Hubert Brooks Hollis, 717 W. Madison Ave., Montebello, Calif. Continuation of application Ser. No. 219,153, Aug. 24, 1962. This application Oct. 19, 1964, Ser. No. 406,658

Claims. (Cl. 318-6) This invention relates to speed control devices, and concerns itself more particularly with apparatus for controlling the speed of electric motors and the like; such as those employed as the prime mover for the coiler of steel slitting machines. This application is a continuation of pending application, Serial No. 219,153, filed August 24, 1962, and entitled Speed Control Apparatus for Steel Slitting Machine.

In the prior art, many speed control devices have been proposed for controlling the speed of electric motors used for driving conveyor belts, continuous strips, recording and film tapes, and even fabric slitting machines, which have not been so in their adaptation to heavy industry, such as sheet steel coiling.

Accordingly, it is a primary object of the instant invention to provide an automatic speed control device for electric motors, and the like, which in turn accurately and effectively control the linear speed of a large, heavy continuous strip such as sheet steel.

Another object of the invention is to provide a speed control device of the type described which is readily adaptable to existing manual controls without extensive alterations.

A further object of the invention is to provide a speed control device of the type described which is adaptable to existing manual controls, and which further provides the quick and easy selection of either manual or automatic control.

Other objects and advantages of the invention will become apparent as the description proceeds, and a more comprehensive understanding of it will be afforded from the following detailed description when considered in conjunction with the accompanying drawings, in which like reference numerals have been used in the different views to designate like parts, and in which:

FIGURES 1 and 2 are plan and side elevational views, respectively, of a steel slitting machine in conjunction with which the instant invention may be used by way of example;

FIGURE 3 is a cross-sectional view of a speed adjusting unit of the speed control device of the instant invention illustrating its adaptation to existing manual controls;

FIGURE 4 is a front view of the unit illustrated in FIGURE 3 taken along the line 4-4 thereof;

FIGURE 5 is a schematic diagram of the speed control device of the present invention showing all parts thereof; and

FIGURE 6 is a wiring diagram of the same illustrating the circuitry for the electrical components thereof.

Although not intended to be limiting in any sense of the word, a preferred embodiment of the invention has been illustrated and will be described in connection with its use for controlling the linear speed of a continuous 3,185,908 Patented May 25, 1965 The slitting machine thus described performs two functionsor operations on the continuous sheet steel strip as it passes from the uncoiler 11 to the coiler 17. Firstly, it shot blasts the strip 20 to remove the scale and rust from both sides thereof and, secondly, it slits it into a number of strips of smaller width and coils them into individual rolls such as 21, 22, 23 and 24.

To properly perform these functions it is necessary to move the sheet steel through the machine at a continuous linear speed. However, the physical characteristics of the material handled, and the machine itself, makes this very difiicult. Usually the roll of steel placed on uncoiler is as much as thick, four feet wide, 700 feet long, and weighs between nine and ten tons. This strip is slit into four strips which are wound on the coiler spindle 25 to form coils having an inside diameter of thirty inches, an outside diameter of sixty inches and weighs over two tons.

Further, the distance between the uncoiler and coiler is approximately eighty feet, and the entire motive power for the movement of the steel through the machine is supplied through the coiler 17, all of which make the movement of the steel strip erratic. Moreover, this condition is further aggravated by the fact that the strip occasionally possesses wrinkles which, as they pass through the guide rolls of the machine, cause the strip to momentarily slow down and then surge forward. Obvious also, is the fact that as the diameter of the coils on the coiler increases, the linear speed of the strip increases. With these conditions imposed, plus the additional requirement that the strip must pass between the shot blast units at a uniform rate of speed to prevent under or over cleaning (pitting), it will be apparent that the speed of the strip through the machine is critical. Also, where production standards or incentive systems are'in effect, it is necessary to have a fixed machine speed as a base upon which time study calculations can be made.

Heretofore the problem of controlling the speed of the strip through the machine has been met by having an operator manually control the speed of the coiler motor at all times during the operation of the machine. Here, the operator is required to continuously observe the speed of the motor on a tachometer graduated to register the linear speed of the strip and manually operate the coiler motor rheostat so as to maintain a constant speed for the strip at, say, fifteen feet per minute. With the injection of the human factor into this operation, overcontrolling of the motor often results. The present invention meets all of the exacting requirements of the aforestated problem and overcomes the deficiency of erratic overcontrol resulting from manual operation.

With reference to FIGURE 5 of the drawings, the speed control'apparatus of the instant invention, in a preferred embodiment thereof, comprises a speed pick-up head, an electric timer, a relay switching device, and a speed adjusting unit (FIGURES 3 and 4) designated, generally and respectively, by the reference numerals 26, 27, 28 and 29. The pick-up head 26 consists of a small rubbertired wheel 30 to which is attached a switch operating cam 31 positioned to actuate a first limit switch 32 and a second limit switch 33. The limit switch 32 is a single pole, single throw switch which is normally open, and switch 33 is of the same type, but normally closed.

In the illustrated use of the apparatus of the present in vention, the pick-up head 26 is mounted on the upper shot blast unit 13 so as to have its wheel 30 frictionally engage the steel strip 20. Here the diameter of the wheel 30 is chosen to translate the linear motion of the strip 20 into rotary motion proportionate to the former. The timer 27 may take any suitable form of those commercially avail- =3: able, such as an Eagle Microfiex Timer, No. C-231, as may the relay 28 which is of the three pole type, with two poles normally open and one pole normally closed.

As illustrated in FTGURES 3 and 4, the speed adjusting unit 29 is contained in a housing 34, which may be attached to an existing speed adjusting device such as a rheostat 37 by conventional fastening means such as screws or the like. A manual control knob 38 for the rheostat 37 is mounted externally of the housing 34 for manual operation of the former through means of a shaft 3?, which shaft by screws 36 is connected to the rheostat as shown in FIGURE 3. Automatic movement of rheostat 37 is effected by means of a reversible speed reducer motor 49 through a gear box 41, a reduction gear 42, and clutch 43 splined to the shaft 39 and movably engageable with a gear wheel 44 of the reduction gear 12. The motor 40 may, for example, take the form of a Bodine speed reducer motor, Type NCl34R, manufactured by the Bodine Electric Company, of Chicago, Ill.

A clutch 43 is engaged with the gear wheel 44 by means of a clutch solenoid acting through a clutch arm as, the former device being under the control of a selector switch 47 operable externally of the housing 34. A friction brake 48 (FIGURE 4) comprising two oak blocks 49 and 50 which are adjustably spring-loaded by means of two butterfly bolt, nut, and spring assemblies 51 and 52, is provided to limit the overtravel of the rheostat 37 at the end of a correcting motion. Here, due to the large gear reduction between the motor 40 and shaft 39, the rheostat 37 would coast past its proper setting if rotation of the shaft were not dampened by the brake 48. It is to be understood that a clutching or electric brake could be substituted for the friction brake if desired.

For the sake of simple description and ease in tracing the circuits for the apparatus as shown in FIGURES and 6, the conductors, lines, and contacts of the various electrical components are designated by letters and reference numerals depicting function. Thus, the control circuit is connected to an electric supply, which may be 110 volts, by the lines L1 and L2, and the connections with these lines at the contact points of the various components are similarly designated. A timing motor of the timer 27 is designated M, and the contacts of the timer by the circled reference numerals as shown in FIGURE 5. Also, a conductor 59 connects the switch 33 to a normally open contact of the relay 28, and a line 64 connects a normally closed contact of the relay to the reverse pole of the motor 4%. Additionally, the timer 27 is further designated TRI to differentiate the same from its contact elements designated TRl-A, TRIB, and TRLC. Similarly, the relay 28 is further designated CR1 to differentiate the same from its contacts CRT-A, CRT-B, and CRI-C. All other components in FIGURES 5 and 6 are shown as previously designated.

In its preferred embodiment and illustrated application, the apparatus controls the speed of the motor 18, and consequently, the speed of the strip 20 through the steel slitting machine. With the pick-up head 26 mounted as shown in FIGURE 2, its pick-up wheel 3% is held in frictional engagement with the strip 20 and is rotated by the movement of the strip through the machine. Here, by way of example only, it will be assumed that for the correct speed of the strip, say fifteen feet per minute, the diameter of the wheel 30 is such that it will be caused to make one complete revolution in four seconds by the movement of the strip 20 at this correct and desired speed. Assuming further that the limit switches 32 and 33 are so mounted that their trips are located three-fourths of a revolution apart, and that the timer 27 (TRI) is set for three seconds, then, as the control cycle is initiated, the cam 31 on wheel Ed is moved to close the limit switch 32. This causes the relay 28 to close (CRT-A and CRT-B to close, CRI-C to open) and lock itself in through L2, 59, and the normally closed switch 33. The closing of relay 28 (CRI-A) initiates the start of the timer 27 (TRI), and

if the strip 2t) is moving at less than its desired speed of fifteen feet per minute, the following events will occur.

At the end of three seconds the cam 31 will not have moved far enough to trip the switch 33, and the timer 27 (TRI) will go into timed out position (TRLC closes and both TRI-A and TRLB open), but will still be energized from relay 28 (CRT-A). In this position, contacts 5658 of timer 27 (TRLC) close, and send a signal to the motor 40 which in turn moves the rheostat 37 to increase the speed of the motor 18, the coiler 17 and lastly the steel strip 23. This circuit is traceable from L2, 59 of the relay 28; 59, 56 of switch 33; and 56, 53 of timer 27 (TRI-C).

The signal just described continues to be sent until the pick-up wheel 30 and its cam 31 rotates to open switch 33, thus opening the holding circuit for the relay 28 previously described. This in turn causes the relay 2% to drop out (CRLA and CRI-B open and CRLC closes), the timer 27 is de-energized and returns to its ofl position, with the result that the motor 4t) ceases to advance. If, on the other hand, the strip 20 is moving faster than its desired speed of fifteen feet per minute, the pick-up wheel 39 and its cam 3-1 will rotate to open switch 33 before the three-second timing interval of the timer 27, initiated as described above, is completed. Consequently, the relay 23 will drop out, but the timer 2'7 (TRI) will continue timing, since it is held in by its own holding circuit L2, 54 (TRi-A) through the jumper from 54 to 53.

A signal is then sent from L2, 54 (TRLA) through the jumper 54 to 53, and 53, se of (CRI-C) to reverse the motor 49, which through the same sequence of operations as described above for increase, decreases the speed of the strip 20. The signal will continue until the timer 27 (TRI) has completed its three-second timing period and is returned to the off position, at which time the motor 46! ceases its retarding motion.

As a third condition, if the strip 20 is moving at its correct and desired rate of speed, fifteen feet per minute, the relay 28 and the timer 27 will both trip out at the same instant and no corrective signal will be sent to the motor 4%). Thus, it is seen that the rheostat 37 may be considered as a controller for any prime mover, such as the motor 18, and that the motor 49 represents a signal responsive means. As such, the latter receives a first signal through the timer switch TRI-C to advance the motor 4% and a second signal through the relay switch CRT-C to retard the same, in which case TRIC may be considered a first switching means and CRLC a second switching means, aside from the other similar elements of both employed to condition holding circuits.

Further, the switch 32 which closes momentarily to condition TRIC to pass a first signal to the motor 40, and CRI-C to pass a second signal to the same upon drop out of CR1, may be considered as a third switching means. Likewise, switch 33 may be considered as a fourth switching means, and the wheel 39 and cam 31 as a rotatable switch operating means. Broadly then, switch 32 which is normally opened, is closed momentarily to initiate a time cycle for timer 27. This timer, as previously described, is conditioned to pass a signal to motor 40 through TRI-C which closes when the timer ends the time cycle for which it is set, defined as timed out position. Further, when the timer is de-energized it assumes its off position and passes no signal. Further, CRI-C which is normally closed, is locked open upon energization of CR1 and closes upon drop out of the latter. TRI-A lOCks TRI (solenoid and motor M) during the period the timer 27 is timing, and TRI-B normally closed, opens when timer 27 assumes its timed out position.

Neglecting the action of the holding circuits for the moment, when switch 32 closes by movement of the rotatable switch operating means 303l, it conditions TRI-C to pass a first signal to motor 44) if timer 27 reaches its timed out position before 30-31 opens normally closed switch 33. Thereafter this signal will continue until switch 33 is opened. If switch 33 is opened by 3031 before the timer 27 has ended the time cycle for which it is set, then a second Signal is passed to motor 40 through CRI-C which moves to its normally closed position when normally closed switch 33 is opened and relay 28 drops out. This signal will continue to be passed by virtue of the fact that TRI is locked in by TRLA until the timer completes its time cycle and returns to its off position. If switch 33 is opened in sequence after the switch 32 is momentarily closed at the same instant the timer 27 has ended the time cycle for which it is set, the latter is de-energized and CRI drops out so that neither a first nor a second signal can be passed to motor 40, and so long as this condition exists, the motor 18 will be operating at its desired speed. If it slows down, the first signal will be sent to motor at), and rheostat 37 will be turned to increase the speed of motor 18; if it runs too fast, the second signal is sent to the motor 40, and rheostat 37 is turned to decrease the speed of motor 18, the speed of the sheet steel strip is increased or decreased, and the speed of travel of 3t)31 is increased or decreased to close the control cycle.

While the normal correct speed for the strip 20 may be fifteen feet per minute, it may be desirable to slow its speed to ten feet per minute for dirtier steel or to increase the speed to twenty feet per minute for cleaner steel. Such an adjustment to the apparatus may easily be made by simply changing the setting on the Eagle Microflex Timer (27) to a different setting. A higher time setting on the dial thereof will cause the strip to run at a slower speed; a shorter timer setting to run faster. These adjustments can be made while the slitting machine is in operation. The sensitivity and response factor of the instant apparatus may be varied by shifting the positions of the trips of the limit switches 32 and 33 in relation to each other, by changing the diameter of the pick-up wheel 30, or by both such changes. And, by proper adjustment the apparatus may be conditioned to hold the speed of the strip 20 within a tolerance of one-tenth of a foot per minute.

Those portions of the control device constituted by the timer 27 and relay 28 may be mounted in any suitable location, while the speed adjusting unit 29 is designed to be mounted on the front of a control panel in place of a rheostat control knob. Additional features of this particular part of the apparatus reside in its means for quickly changing from automatic to manual control. Thus, when the selector switch 47 is moved to Manual the clutch solenoid 45 is de-energized, the clutch 43 is disengaged, and the rheostat 37 is conditioned for manual operation through the shaft 39 by manually turning the knob 38. Also, when the selector switch 47 is turned to Manual the speed control unit is turned off.

Through this expedient, the unit may be conditioned for manual operations and the motor coiler motor 18 may be gradually brought up to the desired speed which will be maintained by the controller apparatus just described. When the slitting machine approaches this desired speed, the selector switch is turned to Automatic and the controller brings it to the correct speed and holds it there.

As a further refinement, this unit can be equipped with limit switches to provide high and low limits for the speed of the coiler motor 18. Further, the unit 29 may be provided with means to automatically return the rheostat 37 to its low limit setting each time the motor 18 is turned off. Such provision will assure that the slitting machine will always be started at slow speed.

Although a preferred embodiment of the invention has been shown and described, and its application in connection with the use of a steel slitting machine presented, it is obvious that the same is susceptible of many other and different embodiments and applications. Thus, to mention only a few, the unit 29 could be used to operate a Reeves Variable Speed Transmission, a US. Varidrive Motor, the throttle of an internal combustion engine, a steam engine, or a braking device, and the device whose speed is to be controlled could take the form of a belt, wheel, vehicle, elevator, etc. On pick-up head 30, the two switches 32 and 33 could be replaced by a single switch actuated by a cam or ramp in such a manner that it would be operated for /4 of a revolution. This would eliminate the holding circuit through CRI-B. CRI would simply turn off and on in conjunction with the switch. The functions of CR1 could be handled by a multi-poled switch that would be physically tripped by the cam or ramp described above. Insofar as these, and all other modifications to which the invention is susceptible, fall within the scope of the appended claims they are considered covered as if described.

I claim:

1. In combination with a machine having an electric prime mover for driving a roll to move a strip of material, a device for manually or automatically adjusting the linear speed of said strip to a desired rate, including:

(a) a rheostat comprising a rotatable shaft for controlling the magnitude of the electric current flowing to said prime mover, said shaft when rotated in a first direction increasing the quantity of said current flowing to said prime mover to increase the rate of rotation of said prime mover and roll, with said shaft when rotated in a second direction decreasing the quantity of said current flowing to said prime mover to decrease the rate of rotation of said prime mover and roll;

(b) first means for manually rotating said shaft;

(c) a reversible electric motor that rotates in a first direction upon receiving a first electric signal and in a second direction upon receiving a second electric signal;

(0.) a clutch interposed between said shaft and motor to permit said shaft to be rotated in either a first or second direction by said motor;

(e) a movable arm for moving said clutch to an engaging or disengaging position;

(f) a solenoid, which when energized, moves said arm to place said clutch in an engaging position to permit said shaft to be rotated by said motor;

(g) a selector switch, which when in a closed position, energizes said solenoid from a source of electric power to permit said shaft to be driven by said motor, with said switch when in an open position permitting said first means to be used to manually rotate said shaft;

(h) a first normally open switch and a second normally closed switch spaced therefrom;

(i) a rotatable cam, which as it rotates sequentially and momentarily, closes said first switch and opens said second switch;

(j) second means for rotating said cam at a rate that is proportional to the linear speed of said strip;

(k) an electrically operated timer which after actuation takes a predetermined period of time to reach a timed-out position, which period is the same length of time as that required by said cam to close said first switch and open said second switch when said strip is moving at said desired rate; and

(I) first and second normally open electrical circuits including holding means, of which said first and second switches and said timer form a part, for sending said first and second signals to said motor, said timer being started when said cam closes said first switch, said first circuit being closed to send said first signal when said timer has reached said timed-out position prior to opening of said second switch by said cam, which first signal continues to be sent until said cam opens said second switch, with said second circuit being closed to send said second signal when said cam opens said second switch prior to said timer reaching said timed-out position, with said second signal continuing to be sent until said timer reaches said timed-out position, and with neither said first nor second circuits being closed it said cam opens said second switch concurrently with said timer as it reaches said timed-out position.

2. A device as defined in claim 1 which further includes relay means for holding said first circuit in a closed condition from the time said timer has reached said timedout position until said cam opens said second switch.

3. A device as defined in claim 1 which further includes relay means for holding said second circuit in a closed condition from the time said second switch is opened by said cam until said timer reaches said timedout position.

4. A device as defined in claim 1 wherein said second means comprises a rubber-tired wheel that is in frictional contact with said strip and rotated thereby.

5. A device as defined in claim 1 wherein said holding means includes a control relay, with relay means for holding said control relay in a closed condition from the time said first switch is closed by said cam until said second switch is opened by said cam.

No references cited.

ORIS L. RADER, Primary Examiner.

Claims (1)

1. IN COMBINATION WITH A MACHINE HAVING AN ELECTRIC PRIME MOVER FOR DRIVING A ROLL TO MOVE STRIP OF MATERIAL, A DEVICE FOR MANUALLY OR AUTOMATICALLY ADJUSTING THE LINEAR SPEED OF SAID STRIP TO A DESIRED RATE, INCLUDING: (A) A RHEOSTAT COMPRISING A ROTATABLE SHAFT FOR CONTROLLING THE MAGNITUDE OF THE ELECTRIC CURRENT FLOWING TO SAID PRIME MOVER, SAID SHAFT WHEN ROTATED IN A FIRST DIRECTION INCREASING THE QUANTITY OF SAID CURRENT FLOWING TO SAID PRIME MOVER TO INCREASE THE RATE OF ROTATION OF SAID PRIME MOVER AND ROLL, WITH SAID SHAFT WHEN ROTATED IN A SECOND DIRECTION DECREASING THE QUANTITY OF SAID CURRENT FLOWING TO SAID PRIME MOVER TO DECREASE THE RATE OF ROTATION OF SAID PRIME MOVER AND ROLL; (B) FIRST MEANS FOR MANUALLY ROTATING SAID SHAFT; (C) A REVERSIBLE ELECTRIC MOTOR THAT ROTATES IN A FIRST DIRECTION UPON RECEIVING A FIRST ELECTRIC SIGNAL AND IN A SECOND DIRECTION UPON RECEIVING A SECOND ELECTRIC SIGNAL; (D) A CLUTCH INTERPOSED BETWEEN SAID SHAFT AND MOTOR TO PERMIT SAID SHAFT TO BE ROTATE DIN EITHER A FIRST OR SECOND DIRECTION BY SAID MOTOR; (E) A MOVABLE ARM FOR MOVING SAID CLUTCH TO AN ENGAGING OR DISENGAGING POSITION; (F) A SOLENOID, WHICH WHEN ENERGIZED, MOVES SAID ARM TO PLACE SAID CLUTCH IN AN ENGAGING POSITION TO PERMIT SAID SHAFT TO BE ROTATED BY SAID MOTOR; (G) A SELECTOR SWITCH, WHICH WHEN IN A CLOSED POSITION, ENERGIZES SAID SOLENOID FROM A SOURCE OF ELECTRIC POWER TO PERMIT SAID SHAFT TO BE DRIVEN BY SAID MOTOR, WITH SAID SWITCH WHEN IN AN OPEN POSITION PERMITTING SAID FIRST MEANS TO BE USED TO MANUALLY ROTATE SAID SHAFT; (H) A FIRST NORMALLY OPEN SWITCH AND A SECOND NORMALLY CLOSED SWITCH SPACED THEREFROM; (I) A ROTATABLE CAM, WHICH AS IT ROTATES SEQENTIALLY AND MOMENTARILY, CLOSES SAID FIRST SWITCH AND OPENS SAID SECOND SWITCH; (J) SECOND MEANS FOR ROTATING SAID CAM AT A RATE THAT IS PROPORTIONAL TO THE LINEAR SPEED OF SAID STRIP; (K) AN ELECTRICALLY OPERATED TIMER WHICH AFTER ACTUATION TAKES A PREDETERMINED PERIOD OF TIME TO REACH A "TIMED-OUT" POSITION, WHICH PERIOD IS THE SAME LENGTH OF TIME AS THAT REQUIRED BY SAID CAM TO CLOSE SAID FIRST SWITCH AND OPEN SAID SECOND SWITCH WHEN SAID STRIP IS MOVING AT SAID DESIRED RATE; AND (L) FIRST AND SECOND NORMALLY OPEN ELECTRICAL CIRCUITS INCLUDING HOLDING MEANS, OF WHICH SAID FIRST AND SECONE SWITCHES AND SAID TIMER FORM A PART, FOR SENDING SAID FIRST AND SECOND SIGNALS TO SAID MOTOR, SAID TIMER BEING STARTED WHEN SAID CAM CLOSES AND FIRST SWITCH, SAID FIRST CIRCUIT BEING CLOSED TO SEND SAID FIRST SIGNAL WHEN SAID TIMER HAS REACHED SAID "TIMED-OUT-" POSITION PRIOR TO OPENING OF SAID SECOND SWITCH BY SAID CAM, WHICH FIRST SIGNAL CONTINUES TO BE SENT UNTIL SAID CAM OPENS SAID SECOND SWITCH, WITH SAID SECOND CIRCUIT BEING CLOSURE TO SEND SAID SECOND SIGNAL WHEN SAID CAM OPENS SAID SECOND SWITCH PRIOR TO SAID TIMER REACHING SAID "TIMED-OUT" POSITION, WITH SAID SECOND SIGNAL CONTINUING TO BE SENT UNTIL SAID TIMER REACHES SAID "TIMED-OUT" POSITION, AND WITH NEITHER SAID FIRST NOR SECOND CIRCUITS BEING CLOSED IF SAID CAM OPENS SAID SECOND SWITCH CONCURRENTLY WITH SAID TIMER AS IT REACHES SAID "TIMED-OUT" POSITION.

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