US2682027A - Motor controlled tensioning apparatus - Google Patents

Description

June 1954 c. E. F. wn |s MOTOR CONTROLLED TENSIONING APPARATUS Filed June 2, 1949 INVENTOR waxm ATT'Y.

Patented June 22, 1954 MO'DOR- CONTROLLED TENSTITONING APPARATUS Claude Edward Frederick Willis, Norburyi London; England, assignor to'R. Hoe & Co. Inc., New York, N; 'Y., a corporation of New York Application June2, 1949, Serial No. 96,778

7 Claims. (Cl. 318-330) This invention relatesto improvements web tension-control mechanism forusel in the web supply for printing and other machines in which the web is drawn from a web roll having associated with it a web tension-changer to exert drag on the roll and hence to impose tension to the web, the changer being under the control of a component which responds to change in web tensionand regulates the changer to maintain a sensibly constant tension.

The present invention has for its main object to provide a. mechanism which shall be simple, relatively inexpensive and which shall prevent any appreciable hunting in the control action.

1 The present invention consists broadly stated in providing an electricalnetwork which is so associated with the responsive component and with a Web-tension changer tooperate on a, webroll that it will transmit electrical impulses to effect impulse actuation of the changer for so long as the responsive component is displaced from a predetermined setting corresponding to a predetermined web tension. The network includesmeans by which the frequency'and the duration of' the impulses can be varied to vary the rate of change of drag exerted on the web roll. ..'I'helinvention is illustrated in the accompanying drawing in which Figure 1 is a diagrammatic elevation of a web-feeding mechanism and Figure 2 is a. wiring diagram. Y ,2 1 Referring firstly to Figure 1, ,this'illustrates a stand I which supports a roll 3 from which a web 4 is drawn by a web-using machine such as a webprinting machine; the web being taken over guide rollers 5 and floating roller 6.

The tension of the web 4 is controlled in the arrangement shown by an endless belt (or belts) 1 which passes over pulleys 8, 9 and IQ of which the-pulley I0 is driven by gears II from the machine and the rate at which the pulley i0 is driven is such that the belt travels slightly slower than the speed at which the web 4 is drawn-on by the machine. The belt 1 thus imposes a drag on the roll 3 and hence on the web 4 being drawn from it so as to produce the web'tension, To enable this tension to be varied to obtain a substantially' constant value, the pulley 8 is, mounted on a frame l2 which is capable of being rocked about the centre of theroll 9 so that .by rocking the frame the extent to which the belt 1 wraps aboutthe roll 3 can be varied, thisvariation producing. a variationin the drag on the roll and a corresponding change in web tension. This var iation is controlled automatically by the drop roller 6 which is mountedonan arm-l3 which-can 2 rock about a centre l4 in response to change in web tension. The movement of this arm l3:con-- trols through a linkage i 5 a switch device It and this switch controls the circuit of a reversible electric motor I1 geared to a shaft IS on which the belt frame 12 is mounted.

As will be described more fully, the switch device It comprises an increase switch and a decrease switch so that. depending on whether the web slackens (in which case the drop roller 6 will move down) or tautens (in which case the drop roller 6 will move up) the forward or reverse circuits of the motor [1 will be closed to movethe belt frame I2 either to increase or decrease thewrap of the belt 1 about the roll 3. t

Mechanism operating in this way to effect con-i trol of web tension is well known and further details are therefore believed to be unnecessary for an understanding of the present invention which is concerned with the particular method of controlling the circuit of the reversible motor I1.

Reference will now be made to Figure 2 in which this control is illustrated. In this figure the tension decrease switch is indicated at 20 and the tension increase switch is indicated at 2| these two switches being linked together as shownfor simultaneous operation by the linkage l5 controlled by the drop roller 6. The switches are in series connection respectively with the reverse coil 24 of the motor l1 and the forward coil 25 of the motor.

The switches 20, 2| are connected in feedlines.

26, 21 which are both connected to the supply line L, through a line 36' having in it a switch so. This switch thus controls the supply to both of the switches 29, 2| and hence to both of the motor coils 24, 25 insofar as they are controlled by the switches 20, 2!.

Now, switch 3!! is electrically operated so that..the supply to the coils 24, 25 under the control of the decrease and increase switches 20, 2! is effected not as a continuous supply but as an intermittent one i. e. the supply is constituted by a series of impulses which will resultin the motor [1 being correspondingly energised and in the belt 1 being moved up or down in a corresponding series of movements. 5

To effect this there is provided an impulsing network indicated within the rectangle A. This network comprises a condenser C shunted by a coil D, and a two-way switch E which is operated by the coil D. Y

The switchE is biased to engage-a contact E charge which connects the condenser C across in accordance with this invention direct current supply lines F, F this charge connection being effected through resistances R, R of which the resistance R is adjustable to enable the rate of charge to be varied. The charging circuit can be traced from the supply line F through the resistances R R to the contact E, thence through the switch arm E and a ballast resistance R to the condenser C, thence through a line F to the supply line F The discharge contact E of the switch E is connected in series with the condenser through resistances R R of which the resistance R is adjustable to enable the rate of discharge of the condenser to be regulated independently of. the rate of charge. The discharging circuit can be traced from one side of the condenser C, through the ballast resistance R to the switch arm E, thence to the contact E to resistances R R through the line F to the other side of the condenser.

The discharge circuit of the network can include directly a coil G to operate the switch 30 by the discharge circuit of the condenser. It is however preferred to use the coil D to operate a relay switch H which is included in series with the coil G across the supply lines F, F This is illustrated in Figure 2, the circuit being traced from the line F to one side of the switch H from the other side of that switch to the coil G and thence to the line F With such an arrangement the condenser C will be charged at a rate governed by the setting of the charge resistance B. When the condenser is charged to a potential which, related to the electrical resistance of the coil D and the mechanical resistance of the switches E and H, is sufficient to operate theswitches the condenser C will be changed-over to the discharge circuit and so will generate an electrical impulse having a duration governed by the setting of the discharge resistance B. When the condenser is discharged to a potential insufficient to hold the coil D energised the condenser C will be transferred back to the charging circuit and so on. Thus a series of control impulses will be generated.

Thus, when either of the increase or decrease switches 20, 2| is moved by the floating roller 6, a corresponding adjustment is made to the belt frame [2 by a series of steps.

The drive for the printing machine would include in the usual manner controls by which the machine can be run at normal running speed or at a slow or inching or crawl speed. It would be arranged that when the motor control is set for normal speed, both the decrease and increase switches 20, 21 would be effective to obtain automatic web-tensicn control. When however the control is set for slow speed running, it would be desirable to arrange that only the tension decrease switch 25 is operative.

To effect this the tension control arrangement includes switches 35, 32 which are respectively operated to close their circuits when the slow and running speed controls are operative. When the slow control is active the switch 3! is closed to complete a circuit from line L to line L? through a relay coil B l which closes a switch 28 in the supply line 26 of the tension decrease" switch 28. At this time switches 23, 29' in the supply line 2'! for the tension increase switch 2| remains open, the switches being operated by arelay coil 33 included with the switch 32 across the supply lines L, U.

When the normal speed switch is rendered active, the switch 32 .is closed. The increase switch 2| is thus also brought into circuit so that the automatic tension control is rendered effective for both the tension increase and decrease conditions.

Both the tension decrease and increase lines 26, 21 include push-button switches by which the belt-arm [2 can be raised and lowered by operator control and this is effected without employing the impulsing arrangement. For this purpose the decrease line 26 has a push button switch 38 which normally closes the automatic control line 26 but which in its operating position completes a circuit through the decrease motor coil 24 from line L to line L through a line 39, which is in shunt across the line 26 with its automatic switch 20. Similarly the increase line includes a push button switch 40 which is normally closed and which when operated opens the automatic control line 21 and closes a line 41 to complete a circuit through the increase coil 25 from line L to line L The web tension circuit would also include a switch 42 which is operated. when the emergency stop switch for the machine is closed. This switch is included in a line 43 with a relay coil 44 across the lines L, L and the coil when energised operates a switch 45 which connects the increase coil 25 across the lines L, L to give full brake action on the roll by causing the belt I to wrap to its full extent about the roll.

The requisite direct current supply to the impulsing network can be obtained when the lines L, L are connected in an alternating current supply by connecting the primary of a transformer 46 across the lines L, L and b feeding the output side of the transformer to a rectifying arrangement 41 of the conventional form.

The motor H for operating the tension control belt I would be of the type having an electromagnetic brake so that on the termination of an operating impulse dispatched to it the motor will be brought quickly to rest.

The impulse generator comprising the charge and discharge circuits referred to could be arranged to be connected into the electrical power supply only when the position of the drop roller .6 calls for tension adjustment. It would however be preferred to have the impulse generator connected into the power supply by the starting of the printing machine.

In the web supply mechanism shown by way of example in Figure 1 the roll 3 is supported by the stand I through a three-arm spider 2 which, in the well-known manner, provides three roll positions. The position occupied by the roll 3 can be regarded as the running position, the position occupied by the roll 3' as the loading position and the position occupied by the third arm can be regarded as a replacement position to which (when .it is about to expire) the roll 3 will be moved. At this time the roll 3 will occupy a position to be engaged and speeded-up by the belt I and it will also occupy a position where its periphery, to which adhesive has been applied, is adjacent the web passing from the expiring roll. Provision is made (such as an arm l9 carrying a brush and a severing knife) by which at the time web-renewal is to be effected the running web from the expiring roll can be deflected against the periphery of the roll 3 by the brush the arm of which would be lowered from the position shown, whereafter the now expiring .web is severed.

The invention is not however limited to any particular type of web-renewing mechanism but is concerned with the maintenance of a uniform tension in a running web.

Equally the invention is not limited to the method of controlling tension by the belt 1. It could be applied also to the type of tension con trol in which a variable braking action is exerted on the core of a web roll. The whole of the impulsing arrangement can be contained in a casing 48 having calibrated dials to set the variable charge and discharge resistances R, R the easing housing also the various relay coils, contactor switches and so on.

What I claim is:

1. In a device for intermittently energizing an electric motor operably connected to a braking device controlling tension of a web running to a machine, an electrical network arranged to generate electrical impulses in a circuit feeding the motor, the said network including a capacitance, a charging circuit, a dis-charge circuit, a changeover switch arranged to connect the capacitance alternately to the charging and discharge circuits, and control means adjustable to regulate the frequency and the duration of the impulses, the said switch being biased toward charging position and magnetically operated to discharge position when the capacitance becomes charged.

2. In a control device for producing electric current impulses in a circuit, a network including a capacitance, a charging circuit, a discharge circuit, a spring biased change-over switch normally connecting the capacitance in the charging circuit, and a coil connected to move the switch and connect the capacitance to the discharge circuit when the capacitance is charged and to release the switch when the discharge current is materially reduced.

3. In a network for supplying an intermittently flowing current to a motor control circuit, and including a condenser, a charging circuit for the condenser, a discharging circuit for the condenser, a double-throw switch associated with the condenser and actuated by a coil connected in parallel with the condenser to open and close the charging and the discharging circuits alternately, and a contact operated with the double throw switch for effecting closure of a feed switch in the motor control circuit only when the charging circuit is closed, thereby feeding current to the motor control circuit intermittently.

4. In a motor controller as defined in claim 3, the combination therewith of variable resistors in the said charging and discharging circuits.

5. In a network having a relay controlled feed switch for supplying an intermittently flowing current to a motor control circuit and including a condenser, a charging circuit for the condenser, a discharge circuit for the condenser, a doublethrow switch associated with the condenser and actuated by a coil connected in parallel with the condenser to open the charging circuit and simultaneously close the discharge circuit, and contacts operated with the double-throw switch to actuate the relay thereby closing the feed switch to supply a pulsating current to the control circuit.

6. In a motor controller as defined in claim 5, the combination therewith of variable resistors in the said charging and discharging circuits.

7. In an electrical network for providing an adjustably timed pulsating direct current to actuate a circuit control switch, a two-way electrically operated switch having charge and discharge switch contacts and normally biased to close the discharge contact, a condenser connected to a first direct current supply line and through a ballast resistance to the two-way switch, a variable charging resistance connected between the charge switch contact and the first supply line, a variable discharge resistance connected between the discharge switch contact and a second direct current supply line, and a switch operating coil connected between the two-way switch and the second supply line for actuating the twoway switch and the relay switch when the coil is energized.

References Cited in the file of thi patent UNITED STATES PATENTS Number Name Date 2,077,600 Watson Apr. 20, 1937 2,155,431 Wieking Apr. 25, 1939 2,254,039 Kovalsky Aug. 26, 1941 2,267,260 Alexander et al. Dec. 23, 1941 2,361,856 McMullen et al Oct. 31, 1944 2,367,049 Petty Jan. 9, 1945v 2,384,830 Garstang Sept. 18, 1945 2,460,064 Curtis Jan. 25, 1949 2,530,749 Yardeny et al. Nov. 21, 1950

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