US3446451A - System for controlling web tension - Google Patents

Description

y 1969 H. R. WILCOX SYSTEM FOR CONTROLLING WEB TENSION Sheet Filed Aug. 22, 1967 FIG.|

AIR SUPPLY AIR ACTUATE BRAKE OR CLUTCH FIG. 2

I INVENTOR. HAROLD R. WILCOX BY 0710M m @JI ATTORNEYS May 27, 1969 H. R. WILCOX Filed Aug. 22, 1967 Sheet 2 012 BRAKE To 64 CLUTCH F I G. 3

\REG. V

INVE NTOR. FIG 4 HAROLD R. WILCOX ATTORNEYS 3,446,451 SYSTEM FOR CONTROLLING WEB TENSION Harold R. Wilcox, Maynard, Mass., assignor to Riggs & Lombard, Inc., Lowell, Mass, a corporation of Massachusetts Filed Aug. 22, 1967, Ser. No. 662,334 Int. Cl. B65h 77/00 US. Cl. 24275.43 10 Claims ABSTRACT OF THE DISCLOSURE A beam carries a tension detecting roller to actuate a ball valve also carried by the beam. The valve is connected to a clutch or brake which controls a roller in engagement with the web. As the tension changes, the beam is moved causing the valve to be actuated and vary the braking or clutching action.

BACKGROUND OF THE INVENTION Field of the invention This invention relates generally to web control systems and more particularly is directed towards a new and improved system for maintaining a uniform longitudinal tension on a moving web.

Description of the prior art There are a great many processes and apparatus which involve a running web where it is desirable to maintain a constant and uniform longitudinal tension On the web as it moves along. For example, in the manufacture of textiles maintenance of web tension is important at various stages of production. Various mechanisms have been developed heretofore for the purpose of controlling the web tension in a predetermined manner. Systems presently available have been found to be generally unsatisfactory for one reason or another. For example, most systems are highly complicated installations involving a great many interacting components all of which must be working perfectly for the system to operate as intended. Generally, systems of this type are highly expensive and because of their complexity tend to be unreliable particularly for long periods of operation. Furthermore, systems presently available are not readily adjustable to accommodate different types of webs. It is therefore an object of the present invention to provide a new and improved system for controlling longitudinal tension on a moving web and one which is of a simple, low-cost construction and which is readily adjustable.

Summary of the invention This invention features a system for controlling web tension comprising a roller mounted on a resilient beam and engaging the moving web. The beam carries a movable nozzle element which is connected to the air supply for an air-actuated clutch or brake. The movable nozzle is provided with a valve element which is positioned by means of a screw adjusting device mounted on a fixed portion of the frame whereby manipulation of the screw adjusting device preloads the beam and allows the valve to bleed air from the system when the web tension reaches a predetermined level. As the web tension increases the valve opens and bleeds air from the air system. This in turn modifies the action of the air brake or clutch which in turn corrects the web tension.

Brief description of the drawings FIG. 1 is a partially sectional view in side elevation and somewhat diagrammatic view of a web tension control system made according to the invention,

FIG. 2 is a detail view in end elevation thereof,

nited States Patent 3,446,451 Patented May 27, 1969 FIG. 3 is a somewhat diagrammatic view in perspective showing a modification of the system, and,

FIG. 4 is a top plan view, also somewhat digrammatic, showing a further modification of the invention.

Description of the preferred embodiments Referring now to FIGS. 1 and 2 of the drawings, the reference character 10 generally indicates a moving web running about a tension detecting roller 12 and thence to a second roller 14 which may be a take-up roller for winding up the web 10 or a driven roller for advancing the web further along. In either event, the roller 14 is drivingly connected to an air-actuated speed control device such as a slip clutch or brake depending upon the particular application. The air-actuated device 16 is connected via a conduit 18 to a source of compressed air with a pressure regulator 20, a gauge 22 and a needle valve 24 being located in the line. Typically the unit 16 will operate at 60 psi. for which will be set on the pressure regulator 20 and the needle valve will be set to pass 1 c.f.rn. of air when operating. These values are only typical and obviously may be varied according to the specific requirements.

The tension detector web roller 12 is supported at its ends by means of bearings 26 one of which bearings is mounted in turn upon a resilient support generally indicated by reference character 28. The resilient support includes a beam arm 30 on the upper surface of which is mounted the bearing 26 and which beam arm extends out from a spacing block 32. The block in turn is fastened to a parallel beam 34 fixed to a mounting stand 36. The block 32 is located off to the side of the vertical center line of the roller and insofar as the beam arm 30 is of a slightly resilient material, such as steel, it will deflect to a certain extent upon the application of a load to the roller 12 as occasioned by tension on the web 10. Typically deflection of the beam will be on the order of .O08"-.0O9".

Carried on the outer end of the beam arm 30 is a nozzle 40 which is connected by a flexible conduit 42 to the conduit 18 which delivers air to the air-actuated device 16. The conduit 42 serves as a bleeder line for the system with the air being delivered into the nozzle at inlet opening 44 and out of the nozzle through an outlet port 46 formed at the base of a conical valve seat 48 formed in the upper face of the nozzle. Trapped in the conical Seat 48 of the nozzle is a ball element 50 which is held by means of an overhead screw 52 threaded through a fixed bracket 54 mounted on the lower fixed beam 34. The screw 52 is provided with a locking nut 56 for locking the screw in a selected position.

With the screw holding the ball fully down against the valve seat the nozzle will be shut off and no air will escape from the bleeding line 42. Under these conditions the air being delivered to the air-actuated device 16 will remain constant and the system will be stable. Assuming that for one reason or another, the tension on the web 10 changes. An increase in the web tension will place a greater load on the tension detecting roller 12 and will cause the beam 30 to deflect downwardly. This movement of the beam 30 will cause the nozzle 40 to drop down to an extent corresponding to the movement of the roller 12 and the beam 30. When the nozzle drops down the air in the bleeder line 42 will be released past the ball element 50, this in turn creating a drop in the pressure in the main air line 18. The decrease in the pressure to the air-actuated unit 16 will cause a reduction in the braking or clutching action imparted to the roller 14 and this, in turn, will decrease the tension on the web 10. As the web tension decreases the beam 30 will rise reducing the amount of air escaping from the nozzle 40 or shutting it off altogether depending upon the amount of correction that takes place in the web tension. In any event, the system will return to a stable condition and the tension on the web will be maintained. In practice, the response is extremely fast and once the tension has been set it will normally remain constant with corrections taking place automatically.

The use of the resilient beam along with a simple flow control valve minimizes air loss and the ball relief type of valve attached directly to the beam has the further advantage in that with the screw adjustment on top to clamp down the ball it is possible to pre-stress the beam and allow the ball valve to bleed only when additional tension occurs on the cloth or web.

The single air line 18 connects with the air-actuated device 16 which typically may be either a disc type of brake or a slip clutch depending upon whether the system is being used in an arrangement for controlling the tension in a brake type of let-off unit or whether it is in use to control tension in the case of rolling up a web. The system has many other uses. For example, for controlling the tension in a let-off unit it may be connected with an air brake. For a centerline type of roll-up or a surface type of roll-up the air pressure to a slip clutch may be controlled in order to maintain a constant controlled tension on the web.

Another use of the system would be in connection with a closed vessel using a fixed shaft with a roll mounted on the fixed shaft. The shaft may be sealed within the sides of the vessel and a sensor of the type disclosed above located on the outside of the unit. The roll can then rotate on the shaft itself within the unit.

In certain applications, as in the textile industry, it is common practice to unroll the web from. one roll onto another and then reverse the direction of the web to rewind the web back onto its original roll. In such applications it is desirable to utilize the slip type of clutch on a specific roll when rolling up and likewise to use an air brake on the same roll when the fabric is being pulled off of this particular roll. Such a system is shown in FIG. 3. In FIG. 3 the reference character 60 indicates a feed roll and reference 62 indicates a take-up roll with the reference character 64 indicating a web passing over a web tension roller 66 mounted in the manner disclosed in FIGS. 1 and 2. As shown in FIG. 3 the take-up roll 62 is operatively connected to an air-actuated slip clutch 68 at one end and an air brake 70 at the opposite end. The units 68 and 70 are provided with conduits 72, 74, 76 and 78 which connect with a solenoid actuated four-way valve 80. The valve 80, in turn, to a source of compressed air. As in the principal embodiment a bleeding line 84 connects with the main line 82 and to a resilient beam actuated nozzle relief valve 86 of the same type as in FIGS. 1 and 2.

The conduits 72 and 78 are bleeding lines which are kept open when either of the units 68 or 70 is inoperative. Depending upon which direction the web 64 is moving the solenoid actuated valve 80 will be shifted to one side or the other to actuate either the clutch or the brake. In winding up a web, the clutch 68 will be employed and the four-way valve will be in the position shown in FIG. 3. This will actuate the clutch and will at the same time bleed air from the brake 70. When the web is being moved in the reverse direction the valve will be shifted to cut off the clutch and deliver air to the brake 70 with the bleeding line from the clutch being open.

Referring now more particularly to FIG. 4 there is shown another modification of the invention and in this embodiment the web tension system is employed in a range drive arrangement. In FIG. 4 a range comprising a series of drive rolls 90 and 92 mounted on a frame 94 is driven by a common drive shaft 96 running along the length of the range. The shaft 96 is drivingly connected to a motor 98 or the like and is employed to transmit driving power to the individual rolls 90 and 92 as through bevel gearing 100. Each roller 90, etc., is provided with an is connected via a conduit 82 air clutch 102 of the slip type with each air clutch operatively connected to a common air supply line 104 by means of a branch line 106. Connected to each branch line is a bleeder line 108 connected to a resilient beam bleeding valve 110 of the sort disclosed in FIGS. 1 and 2. Each valve is operatively connected to a web tension detecting roller 112 and functions in the same manner as in the principal embodiment. The individual sensors are used for controlling the air pressure to the individual slip clutches so that the web may be run through the machine in a synchronized condition.

While the web tensioning system has been disclosed with respect to different specific applications, numerous other applications will appear to those skilled in the art.

Having thus described the invention, what I claim and desire to obtain by Letters Patents of the United States is:

1. A system for controlling web tension, comprising (a) a web-engaging member about which said web travels,

(b) a fixed frame,

(c) a resilient beam mounted at one end to said frame and supporting said member,

(d) a valve having a movable portion carried by said beam and a fixed portion mounted to said frame,

(e) said valve being adapted to open and close upon deflection of said beam in response to changes in web tension,

(f) a pressure responsive fluid actuated device for controlling the speed of said web,

(g) means supplying pressurized fluid to said device and,

(h) a conduit connecting said valve to said means to vary said pressure upon actuation of said valve.

2. A system according to claim 1 wherein said web-engaging member is a roller.

3. A system according to claim 1 wherein said valve includes a ball element trapped between the fixed and movable portions of said valve and a screw threaded through said fixed portion of the frame and engaging said ball element.

4. A system according to claim 1 wherein said fluid actuated device is a brake.

5. A system according to claim 1 wherein said fluid actuated device is a clutch.

6. A system for controlling web tension, comprising (a) a first roll having a length of web wound thereon,

(b) a second roll spaced from said first roll and adapted to wind the web from said first roll,

(0) a pressure responsive fluid actuated clutch operatively connected to said second roll,

(d) a pressure responsive fluid actuated brake operatively connected to one of said rolls,

(e) a multi-position valve connecting said clutch and brake,

(f) control means for operating said multi-position valve for selectively actuating said brake or said clutch,

(g) a pressure relief valve operatively connected to said multi-position valve,

(h) a resilient beam supporting a portion of said relief valve in operative relation to a fixed portion of said relief valve,

(i) web engaging means carried by said beam and adapted to bias said beam and operate said relief valve in response to tension in said web,

(j) operation of said relief valve adapted to alter the pressure to said brake and clutch to maintain tension on said web.

7. A system according to claim 6 wherein said web engaging means is a roller.

8. A system for controlling the tension on a web moving through a range comprising,

(a) a plurality of rollers drivingly engaging said web,

(b) a common drive source for rotating said rollers,

(c) a pressure-responsive fluid-actuated speed control 5 device operatively connected between said source and each of said rollers,

(d) a pressure relief valve for each roller and operatively connected to each device,

(e) means responsive to changes in web tension for actuating said valve whereby pressure at each device will be controlled to maintain tension on said web through said range.

9. A system according to claim 8 wherein said means includes a web engagingmember and a resilient beam supporting said member and fixed to said range, said beam supporting one portion of said valve porting another portion whereby movement of said memand said range supber and beam in response to web tension will actuate said valve.

10. A system according to claim 9 wherein said member is a roller.

5 References Cited UNITED STATES PATENTS 954,089 4/1910 Goss 242-75.43 2,261,891 11/1941 Stewart 242-7543 10 3,330,457 7/1967 Poster et al 24275.43 X

NATHAN L. MINTZ, Primary Examiner.

Images