Title:
Tensiometer control system
United States Patent 2249839


Abstract:
My invention relates, generally, to strip tensioning devices and, more particularly, to means for controlling the operation of tensiometer devices for subjecting a strip of material to tension as it passes between two work devices. In the manufacture of sheet steel, it has been found efficient...



Inventors:
Lessmann, Gerhard P.
Application Number:
US22894138A
Publication Date:
07/22/1941
Filing Date:
09/08/1938
Assignee:
WESTINGHOUSE ELECTRIC & MFG CO
Primary Class:
Other Classes:
72/164, 72/205, 72/453.01
International Classes:
B21B37/50; G01L5/04
View Patent Images:



Description:

My invention relates, generally, to strip tensioning devices and, more particularly, to means for controlling the operation of tensiometer devices for subjecting a strip of material to tension as it passes between two work devices.

In the manufacture of sheet steel, it has been found efficient and economical to subject the steel to tension as it passes in the form of a strip, through a tandem rolling mill. A very successful form of tensioning device for this purpose is disclosed in my copending application Serial No. 133,419, filed March 27, 1937, now Patent No. 2,189,609, to which reference is made for a complete description of its construction and operation. The device disclosed by the above-identified application comprises generally a bell crank upon one arm of which there is mounted an idling roller which bears against the strip as it passes between adjacent roll stands of a tandem mill deflecting the strip from the normal pass line and thus tensioning the strip. The tensioning force is applied to the bell crank by means of a pressure fluid operated piston, the tension being controlled by controlling the fluid pressure acting on the piston and regulating the speed of the rolls of the adjacent roll stands to limit the amount of deflection of the strip by the idling roller.

In some mills it is desirable that such tensioning devices may be capable of producing an extremely wide range of strip tensions, since, for a given, strip thickness, the total strip tension will vary with the width of the strip being rolled if a definite unit tension is desired. Furthermore, each grade of steel requires a different unit tension and this makes it necessary that a wide range of unit tensions be available so that a variety of grades of steel may be rolled in the mill.

In order to expedite the operation of the tensioning device and to render it less dependent upon manual manipulation, it has been found desirable to provide an automatic control system for the tensioning device.

It is, therefore, an object of my invention to provide an automatically controlled tensioning device for a strip rolling mill.

Another object of the invention is to provide a control system for a strip tensioning device which shall function to provide a wide range of tensions.

A-further object of the invention is to provide a control system for a strip tensioning device which shall function to provide a wide range of manually selectable tensions and which shall operate to apply or release the selected tension in response to predetermined mill conditions.

Another object of the invention is to provide a-simple and efficient strip tensioning device for a strip rolling mill-which shall be inexpensive to manufacture, install and maintain.

These and other objects and advantages of my invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which like reference characters designate like elements and-in which: Figure 1 is a diagrammatic illustration of a portion of a strip rolling mill and a strip tensioning device and control therefor embodying the principal features of my invention, Figs. 2 through 8 are diagrammatic illustrations of various control systems for strip tensioning, devices embodying the principal features of my invention.

In its general aspects, a preferred- embodiment of my invention, shown diagrammatically in Fig. 1, comprises a tensioning device 10 actuable by pressure fluid operated pistons 12 and 14, piston 14 having a larger diameter than piston 12, to apply a transverse force to the strip 16 as it passes between adjacent reducing roll stands 18 and 20, thus tensioning the strip. The tension on the strip depends upon the fluid pressure on the operating pistons-and is maintained at a predetermined adjustable amount by a fluid pressure regulating valve 22 which is disposed between a high pressure fluid-reservoir as shown and the operating pistons. This general arrangement of pressure fluid operated strip tensioning device is described in detail in my above referred to copending application to which reference is made for a more detailed description of its structure and operation.

The tensioning device 10 is normally held in an inoperative position, as shown in Fig. 1, by means of a biasing spring 24 which may be compressed and moved out of engagement with the tensioning device by a fluid pressure operated piston 26. An electromagnetically operated valve system 28 selectively causes either piston- 12 or piston 14, depending upon the desired strip tension, to actuate the tensioning device and withdraws the spring 24 from operative relation with the tensioning device.

A generally similar and more simple system is shown in Fig. 2. This figure shows an operating system employing a single piston for operating the tensioning device.

In Fig. 3 there is shown an operating system in which the regulated operating fluid pressure is applied to the operating piston continuously, the biasing spring 24 normally overcoming the force of the operating piston. In this embodiment the tensioning device is operated upon contraction of the spring 24 by the piston 26.

The embodiment shown in Fig. 4 is generally similar to that of Fig. 2 with the two pistons 12 and 14 dperated together.

Another embodiment of the invention is shown in Fig. 5. This system operates essentially the same as that shown in Fig. 3 with the two pistons 12 and 14 operating simultaneously.

The system of Fig. 6 provides selective operation of either or both of pistons 12 and 14, differing from the system of Fig. 1 in that both of the pistons may be operated simultaneously.

A control system by which the two pistons of the system shown in Fig. 5 may be operated selectively is shown in Fig. 7.

The control system of Fig. 8 differs from that of Fig. 7 in that the two operating pistons may be selectively operated separately or simultaneously.

In each of these control systems the actuation of the tensioning device is under the control of a load responsive relay 30 which initiates the operation of the control valve system in response to the load on the roll stand preceding the tensioning device, so that the tensioning device may be in operation when the leading end of the strip bridges the roll stands adjacent the tensioning device.

Referring to the drawings for a more detailed description of my invention, in Fig. 1, the tensioning device 10 comprises a bell crank 32 pivotally mounted upon a support 34. The bell crank 32 has an arm 38 upon which there is rotatably mounted an idling roller 38. The bell crank 32 also has arms 40 and 42, a roller 44 being mounted upon the end of the arm 42 in cooperative relation with a plate member 46 which is biased by the spring 24 to bear against the roller 44 to hold the bell crank 32 in an inoperative position shown in the drawings with the idling roller 38 below the normal pass line between the roll stands 18 and 20.

The plate 46 is connected by a stem 48 to the piston 26 which operates in the cylinder under fluid pressure to retract the plate 46 against the tension of the spring 24 to thus remove the retracting bias from the bell crank 32.

The arm 40 of the bell crank 32 is connected by means of a rod 52 with the pistons 12 and 14 which are operated by fluid pressure in the cylinders 54 and 56, respectively. The actuation of the arm 40 by a predetermined fluid pressure in the cylinder 54 after the spring 24 has been retracted will force the arm 40 upward to rotate the bell crank 32 in a clockwise direction and thus cause the idling tension roller 38 to engage and deflect the strip 16 upward from its normal pass line and thereby subject it to tension. In the preferred embodiment of my invention, the normal operating position of the bell crank 32 will be such that the arm 40 will be substantially horizontal or parallel to the normal pass line between the roll stands 18 and 20 and the arm 36 will be positioned at an angle of substantially 510 from the arm 40. With this positioning of the arms 36 and 40, a substantially constant tension will be maintained in the strip 16 within a predetermined range of deflection of the strip 16 while a constant pressure is applied to the piston which actuates the arm 40. The details of the dimensions and the relative positioning of the arms 36 and 40 are fully discussed in miy above-referred to patent.

Thus, with a predetermined pressure range available through the adjustment of the valve 22, a predetermined range of tensions may be applied to the strip 16 by applying the range of pressures made available by the pressure regulating valve 22 to the piston 12. If a higher strip tension is desired, the predetermined range of fluid pressures made available by the pressure regulating valve 22 may be applied to the piston 14 and the piston 14 being larger than piston 12, a greater force will be applied to the arm 40 for a given pressure on piston 14 than on piston 12. An electromagnetic valve system 28 is provided for selectively actuating the pistons 12 or 14 as desired.

The control for the piston 12 comprises an electromagnetically operated valve 58 which is connected by conduits 60 to a regulated pressure reservoir in which a predetermined pressure is maintained by the pressure regulating valve 22.

The valve 58 is connected by a conduit 62 to the cylinder 54. The cylinder 54 is connected to an electromagnetic valve 64 by means of a conduit 66 and the valve 64 is, in turn, connected by a conduit 68 to the cylinder 50. An electromagnetic operating release valve 70 has one side connected by a conduit 72 to the cylinder 50 and its other side is open to the atmosphere.

A conduit 74 connects a release valve 76 with the conduit 66. The release valve 76 has one side open to the atmosphere.

In a similar manner an electromagnetically operated control valve 78 is connected between the cylinder 56 and the regulated pressure reservoir by means of conduits 80 and 82. A control valve 84 is connected between the cylinder 56 and the conduit 68 by means of conduits 86 and 88 and a conduit 92 connects one side of a release valve 90 with the conduit 86, the release valve 90 having its other side open to the atmosphere.

An electrical control system for the electromagnetic valves is provided and is made responsive to the potential drop across the interpole winding 94 of the drive motor 95 of the roll stand 18. A selector switch 96 is provided to select those parts of the valve control system which will cause piston 12 or 14 to be energized by fluid pressure, as desired. The selector switch 96 comprises a movable contact element 91 which, when moved in the left-hand direction, will engage fixed contact elements 98 and 100, and a second movable contact element 102 which, when moved in the right-hand direction, will engage contact elements 100 and 103. When it is desired to operate the tensioning device 10 by means of fluid pressure applied to piston 12, the selector switch 96 is manually actuated in the left-hand direction and then when the strip is fed through the mill and is engaged by the rolls of the roll stand 18, the increase in the load on the drive motor 95 will energize the relay 30 because of the increase in potential drop across the interpole winding 94, and will close a circuit for the control valves 58, 64, 70 and 76 which extend from one side X of a suitable source of electric current, indicated by conductors XY, through the conductors 104 and 108, the contact element 108 of relay 30, the conductor 110, the winding of valve 70, the conductor 112, the contact element 97, the conductor 114, the operating winding of valve 64, the conductor 116, the operating winding of valve 76, the conductor 118, the operating winding of valve 58-and the conductor 120 to the other power conductor Y.

A similar control circuit is provided for the control valves 78, 84, 90 and 70 which control the operation of the piston 14. This circuit extends from the conductor X through the conductors 104 and 106, contact element 108, conductor 1-10, the operating winding of valve 70, the conductor 112, contact element 102, the conductor 122, the operating winding of valve 84, the conductor 124, the operating winding of valve 90, the conductor 126, the operating winding of valve 78 and conductors 128 and 120 to conductor Y.

The drive motor 130 for the rolls of the roll stand 20 may be manually controlled as indicated to maintain a predetermined amount of slack in- the strip 16 between the roll stands 18 and 20; so that the deflection of the strip 16 by the tensioning device 10 will be maintained within predetermined limits or a suitable regulating device may be provided for the motor 130 to control its speed in accordance with the amount of deflection of the strip 16 by the tensioning device 10, as explained in detail in my hereinbefore referred to copending application.

In the operation of the system of Fig. 1 when a strip of such size or such characteristics as will require only the strip tension available by actuation of the tensioning roll 38 by the piston 12 is to be rolled, the selector switch 98 is actuated manually to move the contact element SS into engagement with the contact elements 98 and 100. When the strip as it is fed through the mill is.engaged by the rolls of roll stand 18, the relay 30 will be energized as hereinbefore described moving its contact elements 108 to closed circuit position. This will energize the valves 58, 64, 70 and 76, as hereinbefore described, to open the valve 58 and admit the pressure fluid to the cylinder 54 to open the valve 64 to admit the pressure fluid to the cylinder 50 to close the valve 7O to prevent fluid flow from the cylinder 50 and to close the valve 76 to prevent fluid flow from the cylinder 54. With the pressure fluid thus made to act upon the pistons 12 and 26, it will be seen that the piston 26 will retract the plate 46 against the tension of the spring 24, thus removing the retracting bias from the tensioning roller 38 and the fluid pressure will act upon the piston 12 to cause the piston to move the tensioning roller 38. to strip tensioning position. While these relays are operating the end of the strip will have progressed from the roll stand 18 to the roll stand 20 and the strip will be in a position, to be engaged by the tensioning roller 38 and.to have tension applied thereto. It is understood-that any suitable time delay may be introduced into the electromagnetic operating system for the valves or the relay 30 may be time delayed so as to permit engagement of the strip 16 by the rolls of roll stand 20 slightly before the tensioning roller reaches the full tensioning position.

When the following end of the strip 16 has passed through the rolls of roll stand 18, it will be seen that the energization of relay 30 will be quickly decreased due to the drop in the load on the drive motor 94 for the rolls of roll stand 18 and the contact element 108 of relay 30 will move to open circuit position causing the deenergization of the valves 58, 64, 70 and 76. The closure of valve 58 will prevent further flow of pressure fluid to the cylinder 54 and the closure of valve 64' will prevent further flow of pressure fluid to the cylinder 50. The opening of the valve 71 will permit flow of pressure fluid from the cylinder 54 to the atmosphere and the opening of the valve 70 will permit the flow of pressure fluid-from the cylinder 50 to atmosphere. With the release of the pressure fluid from the cylinder 54, the operating force will be relieved from the tensioning roller 38 and with the release of the-fluid pressure from the cylinder 50 the retracting force will be released from the spring 24and the spring 24- will force- the plate 46 against the roller 44 on the arm- 42 to move the- tensioningg roller to the inoperative retracted position- shown- in the drawings.

If now the characteristics of the- strip-material 5 or the dimensions of the strip to' be rolled are such as to require a higher tension than can be provided by the piston 1-2, the piston 14, may be placed'into operation by manually actuating the selector switch 96 to cause the contact element 102 to engage the contact elements 1IO and 103.

When the leading end of the strip I1 engages the rolls of roll stand 18, the-relay 30- will be actuated to close the circuit hereinbefore described. to operate the valves 78, 84, 70 and 90; thus operating the piston 26: to remove the retracting bias of the spring. 24 and operating the piston 1-4 to apply tension to- the strip 16; in a manner similar to the operation hereinbefore described in connection with the operation of piston 12.

It will be seen that while the valve system for the piston4 12 is actuated to cause this piston to operate the tensioning device, the valves 18 and 84 will be closed to prevent fluid flow into the cylinder 53. associated with piston It, and, likewise, when the valve system for piston 4: is operated, the valves 58 and 64 will be closed-to prevent pressure fluid flow- into the cylinder 54 associated with piston 12.

In Fig. 2 I have shown an operating system for the tensioning device 10: wherein a single operating piston is connected to actuate the tensioning roller 38, like reference characters in this and the other figures of the drawings desig-5 nating like parts; In this system a selector switch such- as the switch 96 described in connection- with the apparatus of Fig. 1 is not required, and a release valve 90 is also not required. The valve apparatus- comprises a relay control valve 78 connected to the pressure regulating reservoir by conduit 80 and- to the cylinder 56 by conduit 82. A conduit 861 connects the cylinder 50 with the cylinder 56: and the release valve 70 is connected by a conduit 72 to the cylinder 50. The operating- windings of the two control valves 70 and 78 are connected: in a circuit: which extends from conductor X through conductors 104 and 108, the contact element 108, the conductor I10, the operating winding of.valve 70, a conductor 132, the operating winding, of valve 78 and the conductor 134 to conductor Y.

The desired pressure may be established in the regulated pressure reservoir as hereinbefore described in connection with the system of Fig. 1, and when the relay 30 is energized, the valves 70 and 78 will be actuated, the valve 78 then permitting pressure fluid to flow into the; cylinders 58 and 50 and the valve 70 preventing pressure fluid from flowing out of the cylinder 580 By this pressure fluid actuation of the piston 28, the biasing spring 24 will be retracted and the tensioning roller 38 will be moved by piston 14 from the retracted inoperative position shown in the figure to strip tensioning position . When the energization of the relay 30 is decreased,, the valves 70 and 78 will be deenergized by the movement of the contact element 108 of relay 30 to open circuit position. The valve 78 will then close to prevent further flow of pressure fluid to the cylinder 56 and the valve 70 will open to permit flow of the pressure fluid from the cylinders 56 and 50 to the atmosphere. The actuating force will thus be removed from the tensioning device 10 and the retracting force will be removed from the spring 24 permitting the spring to move the tensioning device 10 to the inoperative position shown in the drawings.

In Fig. 3 there is shown another embodiment of the invention in which the operating fluid pressure is maintained constantly upon the operating piston 14 and control valves 84 and 70 are provided for controlling the biasing spring 24'. In this embodiment of the invention, since there is a constant operating force applied to the tensioning device by the piston 14, the retracting spring 24' must be strong enough to counteract the force applied by the piston 14 and to move the tensioning device to the inoperative retracted position against the operating force applied by the piston 14. In order to provide for the retraction of the biasing spring 24', it is necessary to utilize a piston 26' which is larger than the piston 26 described in connection with the devices of Figs. 1 and 2.

The elements of the system comprise the piston 14 operating in the cylinder 56 which is connected to the regulated pressure reservoir by the conduit 80 and to a control valve 84 by a conduit 86. A conduit 88 connects the cylinder 50' with the control valve 84 and the cylinder 50' is connected by a conduit 72 to a release valve 70. A control circuit is provided for the valves and extends from the conductor X through conductors 104 and 106, contact element 108, conductor 110, the operating winding of valve 70, conductor 138, the operating winding of valve 84 and the conductor 140 to the conductor Y.

In the operation of this system when the energization of relay 30 is increased as hereinbefore described, the valve 84 will be opened and the valve 70 will be closed. The opening of vave 84 will permit the flow of pressure fluid to the cylinder 50' and the closure of the valve 70 will prevent the flow of pressure fluid from the cylinder 50'. The application of fluid pressure to the piston 26' in the cylinder 50' will cause the piston 26' to retract the spring 24', thus relieving the retracting bias from the bell crank 32 and permitting the force which is constantly acting upon the bell crank through the piston 14 to move the tensioning device to strip tensioning position. Upon movement of the contact element 108 to open circuit position, the valve 84 will be deenergized and closed, thus preventing further flow of pressure fluid to the cylinder 50' and the valve 70 will be deenergized and opened to permit the flow of pressure fluid from the cylinder 50' to the atmosphere. With the release of fluid pressure from the piston 26', the spring 24' will be allowed to move the bell crank 32 in the counterclockwise direction against the force applied by the piston 14 to move the tensioning roller to inoperative retracted position.

If it is desired to subject the strip to a higher tension than can be provided by the piston 14 alone, the embodiment of the invention shown in Fig. 4 may be employed. In Fig. 4 there is shown the pistons 12 and 14 connected in parallel arrangement in the pressure fluid system to be actuated simultaneously by a control system such as is shown in Fig. 2. By reference to this figure, it will be seen that a conduit 136 is connected to conduct pressure fluid to the cylinder 54 through a conduit 62 and to the cylinder 56 through a conduit 82 simultaneously and that both cylinders 54 and 56 are connected to the conduit 66 which is also connected to the cylinder 50. 'The operation of this system is the same as that described in connection with the system of Fig. 2 with the two pistons 12 and 14 acting simultaneously to provide a strip tension of the order of the sum of the tensions that could be provided by the pistons 12 and 14 acting singly.

In Fig. 5, I have shown a tensioning control system operated substantially the same as the system shown in Fig. 3 with the exception that both of the pistons 12 and 14 are operated simultaneously, as described in connection with the system shown in Fig. 4. In this system it will be seen that a spring 24" is provided, the spring having enough strength to counteract the constant force applied by both pistons 12 and 14 to the tensioning device to hold the tensioning device in the inoperative retracted position. In this system also a larger piston 26" and cylinder 50" are provided to supply the necessary retracting force for the larger biasing spring 24". It will be seen that the cylinders 54 and 56 are both connected by the conduit 80 to the regulated pressure reservoir and both are also connected to the control valve 84. In all respects the operation of this system is substantially the same as the operation of the system described in detail in connection with the showing of Fig. 3.

In case it is desirable that three ranges of tension be provided, the system shown in Fig. 6 may be used. This control system is operative to selectively actuate the tensioning device by either piston 12 or piston 14 or both pistons 12 and 14. The elements of this system are the same as those shown and described in connection with the device of Fig. 1 with the exception of the control circuits for the several valves. In the device of Fig. 6, a selector switch 142 is provided having fixed contact elements 144, 146 and 148 corresponding to the contact elements 98, 100, and 103 of the system of Fig. 1. Movable contact elements 150 and 152 are provided and contact element 150 is so shaped that when it is moved one step in the left-hand direction, the control circuits for the valves which control piston 12 will be energized and when it is moved two steps in the left-hand direction, the control valves for both of the pistons 12 and 14 will be energized. In a like manner when the contact element 152 is moved one step in the right-hand direction, the control valves for the piston 14 will be energized and when it is moved two steps in the right-hand direction, the control valves for both of the pistons 14 and 12 will be energized.

The control circuits for the selection of the operation of either piston 12 or 14 by the movement of the selector switch 142 one step in the left or right-hand directions are the same as those described in detail in connection with the system of Fig. 1 with the movable contact elements 150 and 152 substituted for the movable contact elements 97 and 102 of the device of the system of Fig. 1, and the fixed contact elements 144, 146 and 148 substituted for the fixed contact elements 98, 100 and 103 of the system of Fig. 1. In the second step position of either contact element 150 or 152, it will be seen that the movable contact elements will engage all three of the contact elements 144, 146 and 148, and thus the operating circuits of both sets -of control valves will be ,energized when -the relay -30 moves -its -contact -element 108 to closed.circuit position.

Thus in the operation :of the system of Fig. 6 if it is desiredto provide-a low range of tension on the-strip, the selector.switch 142 may be manually actuated to move the -contact element 1-50 one step into engagement with the contact elements 144 and 1-46 to thus actuate the control valves for the piston 12. If an :intermediate range of tensions is desired, the selector switch 142 may be manually actuated to move the movable contact element 152 one step into :engagement with the contact elements 146 .and 14-8, thus actuating the control valves for the piston 1:4. If it is desired that ;a -still higher :range of tension be ,applied to the strip, the selector switch 1-42 may be manually actuated to.move its movable contact elements IH5O and 1:52 two steps in either the right or left-hand directions to select for ener- ;20 gization the control valvesfor both-of the pistons 12 and 1-4.

In Fig. 7, I have shown a control system for pistons 1.2 and 14 in which either of the pistons may be actuated in a -manner similar to that ;2 shown in Fig. -3. In this: system the control valves .58 and 64 and the release valve 76 are provided for bthe-control of pressure fluid flow to:and from dthe cylinder 54 -and the release valve T0 is pro.vided for the control of pressure fluid flow from ;SC the cylinder -50'. In a like manner control valves .7-8 -and t4 and release valve 90 are -provided for controlling the operation of :piston -14. In this system the spring 24' must be of sufficient strength to overcome the force applied to the bell ;3W crank 32 by the piston -4 under the action of the pressure fluid -similar to that shown in Fig. 3.

A selector switch 154 is provided having movable contact elements 15t and 158 which, when moved in;the left-hand-direction, will establish a connec- 1d tion between fixed contact elements 160 and 162 and 164 and 166, respectively. Movable contact elements 168 and 1710 are also provided and these contact elements when moved in the iright-hand direction will establish connection between the 4 contact elements -162 -and 1t 2 and 166 and 170, respectively.

When the selector switch 154 is actuated in the left-hand direction, the control valve 58 and the release valve 76 will be energized through a cir- '5 cult which extends from the conductor X through the conductor 185, the contact element 158, the conductor -1i8, the operating winding of valve 76, conductor 188, the operating winding of valve 58 and conductor 1i82 to the conductor Y. This :5 energization of valves 58 and 76 will cause valve -58 to open to admit pressure -fluid to the cylinder 54 from -the regulated pressure reservoir and will close valve 76 to prevent the release of pressure -fluid from the cylinder 54. In this 6 condition of the apparatus, the piston 12 will be applying its force to the tensioning device tending to move the tensioning device to operative position -but .this force -will be counteracted by -the biasing spring 24' and the tensioning E device will remain in the retracted inoperative position.

The actuation of the selector switch 154 in the .left-hand =direction will select for operation the control valve 14 and the release valve 10, so that when .the .contact element 108 of the relay 30 is moved to closed circuit position, a circuit will be completed for the valves 64 and 70 extending from the contact .element X to the conductors 104 ýand .106, contact element .108, conductor 110, the operating winding of the valve 70, conductor 112, contact element 156, the conductor 176, the operating winding of valve 64, the conductors 178, 180 and 182 to the conductor Y. This actuation of the valves 64 and -70 will permit the flow of pressure fluid to the cylinder 50' through the conduit 68 and will prevent the flow of pressure fluid from the cylinder 50' through the conduit 72, thus subjecting the piston 26' to fluid pressure to retract -the spring 24' and permit the piston 12 to move the tensioning device to operative position.

In a like manner when the selector switch 154 is actuated in the right-hand direction, a circuit will be closed to energize the control :valve 78 and the release valve 90, the circuit extending from the conductor X through the conductor 185, contact element 170, the conductor 90, the operating winding of valve 90, the 9 conductor 192, the operating windindg of valve 78 and conductors 194 and 182 to the conductor Y.

Athee ti the same timethe control valve 84 and the release valve 70 will be selected for operation by the engagement of contact element 168, with contact elements 162 and 172 through a circuit extending from conductor X through conductors 104 and 106, contact element 108, when it is in closed circuit position, conductor 110, the operating winding of valve 70, conductor 112, contact element 168, conductor 184, the operating winding of valve -84 and the conductors 1-80 and 182 to the conductor Y. Thus the valves 78 and -90 will be selectively operated by the actuation of the selector switch 154 in the right-hand :direction to apply operative force to the tensioning device through the piston 14 and then when the relay '30 moves its contact 108 to its closed circuit position, the valves 70 and 84 will be operated to cause the piston 26' to retract the spring 24' and permit the tensioning device to be operated by the piston 14. Thus it will be seen that the control system of Fig. 7 will selectively actuate the tensioning device by either piston 12 to provide a low range of tensions or cby the piston 14 to provide a higher range of "tensions.

If a low range of tensions, an intermediate orange of tensions and a high range of tensions are desired, the control system of Fig. 8 may 0 be employed. This system will so control the actuation of the tensioning device as to provide a range of tensions with piston 12 acting alone, .piston 14 acting alone or pistons 12 and 14 acting together. This system is very similar to that Sshown in Fig. 7, except that a -selector switch -similar to the selector switch shown in the system of Fig. 6 is provided. In this system the biasing spring 24" -must be made strong enough to counteract the forces applied to the tensioning Sdevice by both pistons 12 and 14 and the piston .26" must be of sufficient size to counteract the biasing spring 24" as was explained in connection with the system of Fig. 5.

In the system of Fig. 8, a selector switch 196 ;5 is provided having movable contact elements 200 and 202 which when moved one step in the left-hand direction will engage contact elements 204 and 206 and 208 and 210, respectively, and when moved two steps in the left-hand direction '0 will engage contact elements :204, 206 and -216 and contact elements 208, 210 and 218, respectively. The selector switch 196 also includes movable contact elements -212 and 214 which when the selector switch is moved one step in 75 the right-hand direction will engage contact elements 204 and 216 and contact elements 208 and 218, respectively, and when moved two steps in the right-hand direction will engage contact elements 204, 206 and 216 and 208, 210 and 218, respectively. Thus the first step in the movement of the selector switch 196 in the left-hand direction will actuate the control valve 58 and the release valve 7S for the piston 12 through a circuit which extends from the conductor X through the conductor 232, contact element 202, conductor 234, the operating winding of valve 76, conductor 236, the operating winding of valve 58 and conductor 228 to the conductor Y. At the same time a circuit will be selected by the engagement of movable contact element 200 with contact elements 204 and 206 which, when the contact element 108 of relay 30 is moved to closed circuit position, extends from the conductor X to the conductors 104 and 106, the contact element 108, conductor 110, the operating winding of valve 70, conductor 112, contact element 200, conductor 220, the operating winding of valve 64, and conductors 224, 226 and 228 to the conductor Y.

In a like manner, when the selector switch 196 is moved one step in the right-hand direction, a circuit extending from conductor X through the conductor 232, contact element 214, conductor 238, the operating winding of the valve 90, conductor 240, the operating winding of valve 78, and conductors 244 and 228 to the conductor Y will be energized to actuate the valves 78 and 90.

At the e same time a circuit will be selected for actuating the valves 84 and 70 when the relay 30 moves its contact element 108 to closed circuit position through a circuit which extends from conductor X through conductors 104 and 106, contact element 108, conductor I !0, the operating winding of valve 70, conductor 112, contact element 212, the conductor 230, the operating winding of valve 84 and the conductors 226 and 228 to the conductor Y. If now it is desired to actuate the tensioning device by both pistons 12 and 14, the selector switch 196 may be moved in either direction two steps to energize the selector circuits for the control valves 58 and 78 and the release valves 76 and 90 simultaneously and to set up the control circuits for the control valves 64, 84 and 70 as hereinbefore described.

It will be seen that I have provided control systems for a fluid pressure operated strip tensioning device which will function to subject a strip of material to any desired range of tensions which will automatically hold the tensioning device in retracted inoperative position while 5 the strip is not in a position to be tensioned by the device, and which, when the strip moves to a position to be tensioned by the device, will automatically operate to apply the desired tension to the strip. 6 In compliance with the requirements of the patent statutes I have shown and described herein the preferred embodiments of my invention. It is to be understood, however, that the invention is not limited to the precise construc- 6; tions shown and described but is capable of modification by one skilled in the art, the embodiments herein shown being merely illustrative of the principles of my invention.

I claim as my invention: 7( 1. In a control system for a strip tensioning device having an idling roller disposed to bear against the strip when actuated to deflect it from its normal pass line as it passes between two work devices to thus subject the strip to tension, 73 means for biasing the roller for movement away from strip tensioning position, counteracting means for rendering said biasing means inoperative to act upon the roller, means for actuating the roller to strip tensioning position and control means for selectively rendering said counteracting means effective or ineffective.

2. In a control system for a strip tensioning device having an idling roller disposed to bear against the strip when actuated to deflect it from its normal pass line as it passes between two work devices to thus subject the strip to tension, means for biasing the roller for movement away from strip tensioning position, counteracting means for rendering said biasing means inoperative to act upon the roller, means for actuating the roller to strip tensioning position, and control means for actuating said counteracting means and said roller actuating means.

3. In a control system for a strip tensioning device having an idling roller disposed to bear against the strip when moved to strip tensioning position to deflect it from its normal pass line as it passes between two work devices to thus tension the strip, a first means biasing the roller for movement toward strip tensioning position, a second means for biasing the roller for movement away from strip tensioning position, said second biasing means having sufficient force to move the roller away from strip tensioning position against the force of said first biasing means, and counteracting means for rendering said second biasing means inoperative to act upon the roller.

4. In a system for subjecting a strip of material to tension as it passes between two adjacent work devices, an idling roller disposed to be made to bear against the strip and thus subject the strip to tension by deflecting it from its nor0L mal pass line between the work devices, means for biasing the idling roller for movement away from strip tensioning position, counteracting means for rendering said biasing means inoperative to act upon the roller, means for moving said l5 roller to strip tensioning position, and means responsive to the positioning of the leading end of the strip as it passes through said work devices for actuating said counteracting means and said means for moving said roller to strip ten0 sioning position.

5. In a system for subjecting a strip of material to tension while it passes between two adjacent work devices, an idling roller disposed to be actuated into engagement with the strip and thus 5 subject the strip to tension by deflecting it from its normal pass line between the work devices, means for biasing the idling roller for movement away from strip tensioning position, counteracting means for rendering said biasing means in0 operative to act upon the roller, means for moving said roller to strip tensioning position, and means responsive to the position of the strip with respect to said work devices for so actuating said counteracting means and said means for moving J said roller to strip tensioning position as to subject the strip to tension during the time it extends between and is engaged by the work devices.

6. In a system for subjecting a strip of material to tension while it passes between two adjacent work devices, an idling roller disposed to be actuated into engagement with the strip and thus subject the strip to tension by deflecting it from its normal pass line between the work devices, means for biasing the roller for movement away from strip tensioning position, a first operating means for causing the roller to engage and apply a predetermined force to the strip, a second operating means for -causing the roller to engage :and apply a predetermined force to the strip, counteracting means :for rendering said biasing means inoperative to act upon the roller, and means for'selectively actuating said first and second operating means and for actuating said counteracting means. 1 7. In a system for subjecting a strip of material to tension while it passes between two adjacent work devices, an idling roller disposed to be actuated into engagement with the strip and thus subject the strip to tension by deflecting it 1 from its normal pass line between the work devices, means for biasing the roller for movement away from strip tensioning position, a first operating means for causing the roller to engage and apply a :predetermined force to the 2 strip, a second operating means for causing the roller to engage and apply a predetermined force to the strip, counteracting means for rendering said biasing means inoperative to act upon the roller, and means for selectively actuating 2 either or both of said first and second operating means and for actuating said counteracting means.

8. In a control system for a strip tensioning device having an idling roller adapted to be 3 actuated into engagement with the Estrip to deflect it from its normal pass line as it passes between two work devices to thus subject the strip to tension, a first operating means for causing the roller to engage and apply a predetermined force to the strip, a second operating means for causing the roller to engage and apply a predetermined force to the-strip, means-biasing the roller for movement away from strip tensioning position, said biasing means having sufficient force to move the roller away from strip tensioning position against the force -of either said first or said second operating means, means for counteracting said biasing means, means for selectively actuating said first and second operating means, and means for actuating said counteracting means.

9. In a control system for a strip tensioning device having an idling roller adapted to be actuated into engagement with the strip to deflect it from its normal pass line as it passes between two work devices to thus subject the strip to tension, a first operating means for causing the roller to engage and apply a predetermined force to the strip, a second operating means for causing the roller to engage and apply a predetermined force to the strip, means biasing the roller for movement away from strip tensioning position, said biasing means having sufficient force to move the roller away from strip tensioning position against the force of both said first and said second operating means combined, means for counteracting said biasing means, means for selectively actuating either or both of said operating means, and means for actuating said counteracting means.

10. In a system for subjecting a strip of material to tension while it passes between two adjacent work devices, an idling roller disposed to be actuated into engagement with the strip and thus subject the strip to tension by deflecting it from its normal pass line between the work devices, means biasing said roller away from strip tensioning position, pressure fluid operated means for counteracting said biasing means to remove its bias from said roller, pressure fluid operated means for actuating said roller to strip tensioning position, inlet valve means for admitting pressure fluid to both ýof Ssaid pressure fluid operated means, outlet valve means for permitting pressure fluid to flow from both of said pressure fluid operated means, means for simultaneously opening said inlet valve means and closing said outlet valve means, and means 0 for simultaneously closing said inlet valve means and opening said outlet valve means.

11. In a system for subjecting a strip of material to tension while it passes between two adjacent work devices, an idling roller disposed to be actuated into engagement with the strip and thus subject the strip to tension by deflecting it from its normal pass line between the work devices, means biasing said roller away from strip tensioning position, pressure fluid operated ;0 means for counteracting said biasing means to remove its bias from said roller, pressure fluid operated means for actuating said roller to strip tensioning position, means for maintaining fluid pressure on said pressure fluid operated roller ;5 actuating means, said roller biasing means having sufficient force to hold said roller away from strip tensioning position against the force of said roller actuating means, inlet valve means for admitting pressure fluid to said pressure fluid i0 operated counteracting means, outlet valve means for permitting pressure fluid to flow from said counteracting means, means for simultaneously opening said inlet valve means and closing said outlet valve means, and means for simultaneously 35 closing said inlet valve means and opening said outlet valve means.

12. In a system for subjecting a strip of material to tension while it passes between two adjacent work devices, an idling roller disposed 40 to be actuated into engagement with the strip and thus subject the strip to tension by deflecting it from its normal pass line between the work devices, means biasing said roller away from strip tensioning position, pressure fluid op45 erated means for counteracting said biasing means to remove its bias from said roller, pressure fluid operated means for actuating said roller to strip tensioning position, inlet valve means for admitting pressure fluid to both of said 50 pressure fluid operated means, outlet valve means for permitting pressure fluid to flow from both of said pressure fluid operated means, means for simultaneously opening said inlet valve means and closing said outlet valve means, and means 55 for simultaneously closing said inlet valve means and opening said outlet valve means, said means for actuating said roller comprising a plurality of pressure fluid operated pistons.

13. In a system for subjecting a strip of ma60 terial to tension while it passes between two adjacent work devices, an idling roller disposed to be actuated into engagement with the strip and thus subject the strip to tension by deflecting it from its normal pass line between the work 65 devices, means biasing said roller away from strip tensioning position, pressure fluid operated means for counteracting said biasing means to remove its bias from said roller, pressure fluid operated means for actuating said roller to strip tensioning 70 position, means for maintaining fluid pressure on said pressure fluid operated roller actuating means, said roller biasing means having sufficient force to hold said roller away from strip tensioning position against the force of said 75 roller actuating means, inlet valve means for admitting pressure fluid to said pressure fluid operated counteracting means, outlet valve means for permitting pressure fluid to flow from said counteracting means, means for simultaneously opening said inlet valve means and closing said outlet valve means, and means for simultaneously closing said inlet valve means and opening said outlet valve means, said means for actuating said roller comprising a plurality of pressure fluid operated pistons. 14. In a system for subjecting a strip of material to tension while it passes between two adjacent work devices, an idling roller disposed to be actuated into engagement with the strip and thus subject the strip to tension by deflecting it from its normal pass line between the work devices, means biasing said roller away from strip tensioning position, pressure fluid operated means for counteracting said biasing means to remove its bias from said roller, pressure fluid operated means for actuating said roller to strip tensioning position, said means for actuating said roller to strip tensioning position comprising a plurality of pressure fluid operated pistons, an inlet valve for each of said pistons for admitting pressure fluid to said pistons, an outlet valve for each of said pistons for permitting pressure fluid flow from said pistons, a control valve connected in a fluid conduit between each of said pistons and a common conduit connected to said counteracting means, an outlet valve for said counteracting means, control means for selectively simultaneously opening the inlet valve, closing the outlet valve, and opening the control valve for any one of said pistons and closing the outlet valve for said counteracting means and for simultaneously actuating said selectively operated valves to the positions opposite to their selectively actuated positions.

15. In a system for subjecting a strip of material to tension while it passes between two adjacent work devices, an idling roller disposed to be made to bear against the strip and thus subject the strip to tension by deflecting it from its normal pass line between the work devices, means 4 biasing said roller away from strip tensioning position, pressure fluid operated means for counteracting said biasing means to remove its bias from said roller, pressure fluid operated means for actuating said roller to strip tensioning position, said means for actuating said roller to 50 strip tensioning position comprising a plurality of pressure fluid operated pistons, an inlet valve for each of said pistons for admitting pressure fluid to said pistons, an outlet valve for each of said pistons for permitting pressure fluid flow from said pistons, a control valve connected in a fluid conduit between each of said pistons and a common conduit connected to said counteracting means, an outlet valve for said counteracting means, control means for selectively simultaneously opening the inlet valve, closing the outlet valve, and opening the control valve for any one or all of said pistons and closing the outlet valve for said counteracting means and for simultaneously actuating said selectively operated valves to the positions opposite to their selectively actuated positions.

16. In a system for subjecting a strip of material to tension while it passes between two adSjacent work devices, an idling roller disposed to be made to bear against the strip and thus subject the strip to tension by deflecting it from its normal pass line between the work devices, means biasing said roller away from strip tensioning position, pressure fluid operated means for counteracting said biasing means to remove its bias from said roller, pressure fluid operated means for actuating said roller to strip tensioning position, said means for actuating said roller comprising a plurality of pressure fluid operated pistons, said roller biasing means having sufficient force to hold the roller away from strip tensioning position against the force of all of said plurality of pistons, an inlet valve for each of said pistons for admitting pressure fluid to said pistons, an outlet valve for each of said pistons for permitting pressure fluid flow from the pistons, a control valve connected in a fluid conduit between each of the pistons and a common conduit connected to said counteracting means, an outlet valve for said counteracting means, control means for selectively simultaneously opening the inlet valve, and closing the outlet valve for any one or all of said pistons, control means for thereafter simultaneously opening the control valve of the piston or pistons whose inlet and outlet valves have been selectively operated and closing said counteracting means outlet valve.

GERHARD P. LESSMANN.