System For Controlling Application Of Braking Force To A Roll Of Sheet Material

Abstract

A system for controlling the application of braking force to a roll of sheet material in which a sensing member controlled by the diameter of the unwinding roll, moves a cam surface to actuate a control device that in turn controls the energization of a brake for such roll, the cam surface being adjustable to provide a braking force that may be varied from zero to a predetermined amount between the extreme ranges of the maximum and minimum roll diameters.

Description

As conducive to an understanding of the invention, it is noted that where a roll of sheet material is mounted on a shaft and the sheet material is drawn from the roll by a subsequent machine which, for example, may be driven printing rollers between which the sheet is drawn at relatively constant high speed, it is important that the unwinding of the sheet from the roll be controlled by suitable braking action to prevent overrunning of the sheet due to the inertia of the roll and also to maintain a constant tension on the sheet.

Where mechanical devices are employed, such as counterweight systems acting on a brake reacting against the roll shaft, they are difficult to adjust and generally do not permit high unwinding speeds.

Where complex electrical or electronic systems are employed to vary the braking action, in addition to being expensive in cost, they are difficult to maintain.

It is accordingly among the objects of the invention to provide a system for controlling the application of braking force to a roll of sheet material, which system has relatively few parts which may readily be assembled and which are not likely to become deranged even with long use and which permits adjustment of the braking force applied to the roll even while the latter is unwinding to insure that uniform tension may be applied to the sheet as it is withdrawn from the roll and also to insure that a braking force will be applied to the roll even when the latter is substantially unwound.

Another object of the invention is to provide a system of the above type in which a cam member operatively engages a control device which in turn controls the amount of braking force, which cam device is moved by a sensing arm, the position of which is determined by the diameter of the roll and which cam member has a cam surface that is adjustable even while the cam member is moved by the sensing arm to provide a braking force that may be varied from zero to a predetermined value between the extreme ranges of the maximum and minimum roll diameters.

According to the invention, the roll of sheet material is mounted on a shaft illustratively positioned in a horizontal plane, which shaft has a brake device illustratively of the pneumatic type associated therewith.

A control device is provided comprising a sensing arm illustratively having a roller on its free end engaging the periphery of the roll of sheet material, and having its other end secured to and extending at right angles from the control shaft of the control device so that the angular position of the control shaft will be determined by the diameter of the roll.

The control shaft is urged by suitable means in direction to urge the roller end of the sensing arm against the periphery of the roll.

The control shaft rigidly mounts a plate extending at right angles thereto, the plate in turn carrying a cam member in the form of an arcuate strip pivoted at one end to the plate on an axis extending at right angles to the plate. The pivot mount of the strip is an eccentric adjustment pivot so that the outer arcuate periphery of the cam strip may be moved toward and away from the axis of the control shaft.

The free end of the arcuate strip rests on a second adjustment member having an eccentric cam surface on which such free end rests. Associated with the cam member is a valve, illustratively an air valve, which has an actuating rod with a roller at its free end adapted to ride on the arcuate outer surface of the cam.

By adjusting the position of the pivotal mount of the arcuate cam as well as the position of the support for the free end of the arcuate cam with respect to the axis of the control shaft, braking force may be provided not only at the commencement of withdrawal of sheet material from the roll, but also when the roll is substantially empty.

In the accompanying drawings in which is shown one of various possible embodiments of the several features of the invention,

FIG. 1 is a fragmentary side elevational view of the control device;

FIG. 2 is a sectional view taken along line 2--2 of FIG. 1,

FIG. 3 is a sectional view taken along line 3--3 of FIG. 1;

FIG. 4 is a graph illustrating the operation of the equipment, and

FIG. 5 is a diagrammatic view showing the control device associated with the roll of sheet material.

Referring now the drawings, as shown in FIG. 5, the roll 11 of sheet material has an axial bore through which extends a shaft 12. One end of the shaft is suitably mounted in a bearing 13 in a vertical frame 14 and the other end of the shaft is mounted in a bearing 15 in a vertical frame 16 which also carries the control device C, the shaft 12 extending through said bearing 15 as at 17.

As shown in FIG. 5, suitable clamp members 18 are mounted on the shaft 12 on each side of the roll 11 and are moved tightly against opposed ends of the roll and locked to the shaft by set screws 19 so that the shaft will rotate with the roll.

Brake mechanism 21 supported by the frame 16 is operatively connected to the protruding end 17 of the shaft to control the rotation of the latter. In the illustrative embodiment shown, the brake 21 is a pneumatic brake controlled by the flow of air under pressure from a valve 22, also shown in FIG. 1.

The frame 16 has spaced parallel transverse supporting members 23 and 24, each of which has an aperture 25 therethrough in which a bearing 26 is mounted. Extending through said bearings is a control shaft 27, the outer end of which mounts a hub 28 which is secured to the shaft 27 by set screw 29.

The hub 28 has extending radially therefrom a sensing arm 31, which, as shown in FIGS. 1 and 5, mounts a roller 32 at its free end designed to be urged against and ride on the periphery of the roll 11 adjacent one end of the roll for example. The other end of the shaft 27, which extends beyond the bearing support 24, mounts a hub 33 which is secured thereto by set screw 34. By reason of the two hubs 28 and 33, the shaft 27 is free to rotate in its bearings 26, while being restrained from axial movement.

The hub 33 is formed integral with the axis of a radially extending sector plate 35, more clearly shown in FIG. 1, the outer periphery 36 of said plate 35 being arcuate as shown. The sector plate 35 adjacent its periphery 36 has a bore 37 therethrough (FIG. 2) which is internally threaded to receive the correspondingly threaded end of a pin 38 which is headed as at 39. The pin 38 extends through the bore 41 of an adjustment sleeve 42, said bore 41 being displaced from the axis of the sleeve 42 so that the latter will be eccentrically mounted on pin 38.

As is clearly shown in FIG. 2, the adjustment sleeve 42 extends outwardly at right angles from the face of sector plate 35 and the reduced diameter portion 43 of sleeve 42 extends through a corresponding bore 44 adjacent one end of a cam member 45.

As is clearly shown in FIG. 1, the cam member 45 is a strip substantially arcuate in contour and more particularly has an arcuate outer edge 46 and two arcuate portions 47 and 48 at its inner edge, the width of the cam member 45 being greatest at the portion thereof defined between the outer edge 46 and the inner edge portion 47.

As shown in FIGS. 1 and 3, the sector plate 35 has an additional bore 49 therethrough which is circumferentially displaced from the bore 37 and positioned closer to the axis of shaft 27 than is bore 37. A headed screw 51 has its inner end screwed into bore 49 and extends through the bore 52 of a second or main adjustment sleeve 53. As is clearly shown in FIG. 3, the bore of adjustment sleeve 53 is of reduced diameter at its inner end defining a passageway 54 through which the screw extends. A hub or collar 55 positioned in the enlarged portion of bore 52 encompasses the end of the screw 51.

The inner end 56 of sleeve 53 defines a cam surface 56a which is eccentric with respect to the axis of screw 51. As is clearly shown in FIG. 3, when the roll 11 is full, the arcuate portion 48 of cam 45 will rest on the cam surface 56a of said main adjustment sleeve 53.

Mounted on the frame 16 is the valve 22 which in the illustrative embodiment shown is a pneumatic valve to control flow of air under pressure from a pneumatic source to the pneumatic brake 21 which may be of any conventional type. The valve 22 is mounted in position such that the axis of a roller 59 at the lower end of the control rod 61 of the valve 22 will be in the same vertical plane as the axis of shaft 27 and in the position shown with the roll having its maximum size would also be in the same vertical plane as the axis of pin 51.

As shown in FIGS. 1, 2 and 5, the shaft 27 mounts a sprocket wheel 62 having an axial hub 63 secured to the shaft 27 by a set screw 64. The sprocket wheel 62 is encompassed by a sprocket chain 65 which also rides around a sprocket wheel 66 which is normally urged in a clockwise direction, referring to FIGS. 1 and 5 by a suitable coil spring S so that the shaft 27 as well as arm 31 and the roller 32 thereon will also be urged in a clockwise direction in order to maintain the roller 32 against the periphery of the roll 11 as the latter becomes of reduced diameter as the material thereon is unrolled, the stops S' limiting rotation of sector plate 35 and shaft 27.

In the operation of the system, by rotation of the adjustment sleeves 42 and 53 the arcuate surface 46 of the cam 45 may be set to a position in which it is part of the arc of circle having the axis of control shaft 27 as its center.

It is apparent that with the cam 45 so set, movement of the cam by the sensing arm as the roll 11 unwinds would not cause any movement of the control rod 61 of valve 22. Hence, the valve would remain closed and the brake 21 would not be actuated.

In order to provide desired control of the brake, it is merely necessary to rotate the adjustment sleeve 42 to move the pivoted end of the cam closer to the axis of control shaft 27 and to rotate the adjustment sleeve 53 to move the free end of the cam further away from the axis of the control shaft.

As a result, the control rod 61 will be actuated in both the maximum and minimum diameter conditions of the roll so that the braking force may be exerted by the brake on the roll shaft 12.

It is apparent that such adjustments may be made even while the roll is unwinding and that the cam may be set to any desired position within the limits provided by the adjustment sleeves 42, 53.

In the graph shown in FIG. 4, the abscissa O-X represents the pressure provided by the brake and the ordinate O-Y represents the movement of the cam. The origin O represents the setting of adjustment sleeve 42 in which the pivoted end of the cam 45 is farthest from the axis of the control shaft as shown in FIG. 1.

With this setting, when the sensing arm 31 has moved the sector plate 35 so that the roller 59 is aligned with the axis of adjustment sleeve 42 (which occurs when the roll 11 is substantially empty), the control rod 61 will be fully extended and the air under pressure to the brake 21 will be cut off so no braking action is present.

The position O-1 on the graph represents the setting of adjustment sleeve 42 in which the pivoted end of cam 45 is closest to the axis of control shaft 27.

With this latter setting, when the sensing arm 31 has moved the sector plate 35 so that the roller 59 is aligned with the axis of adjustment sleeve 42, the control rod 61 will be retracted to cause the valve 22 to apply air under pressure to brake 21 so that a braking force will be applied to shaft 12 when the roll is substantially unwound.

It is apparent that by varying both adjustment sleeves 42 and 53 an infinity of intermediate curves can be obtained.

Claims

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A system for controlling the application of a braking force to a roll of sheet material mounted on a shaft with which a brake coacts, said system comprising a control shaft, a sensing device to effect angular displacement of said control shaft about its axis by an amount proportional to the decrease in diameter of said roll as the sheet material is withdrawn therefrom, a movable member controlling said brake to determine the actuation of said brake based on the displacement of said movable member, a plate secured to said control shaft and extending radially therefrom, a cam member comprising a strip having an arcuate outer cam surface engaged by said movable member, said strip being pivoted at one end to said plate on an axis extending at right angles to said plate and having its other end resting on a support secured to said plate and extending at right angles thereto, and means to adjust the distance between the pivoted end of said arcuate strip and the supported end of said arcuate strip from the axis of said control shaft, whereby the position of said cam member may be adjusted with respect to said control shaft to set the force exerted by said brake on said roll shaft as the diameter of said roll increases.

2. The system set forth in claim 1 in which said sensing device comprises a control arm affixed at one end with respect to said control shaft and extending at right angles with respect thereto, the free end of said control arm mounting a roller adapted to ride on the periphery of such roll.

3. The system set forth in claim 1 in which resilient means is provided normally urging said control shaft in direction to retain said roller against the periphery of such roll.

4. The system set forth in claim 1 in which the axis of said control shaft and the axis of said roll lie in the same vertical plane.

5. The system set forth in claim 1 in which a first adjustment sleeve is eccentrically mounted on the axis of said strip, said strip having an opening through which said sleeve extends to define the pivotal mount for said strip whereby upon rotation of said sleeve, the pivoted end of said strip may be moved toward and away from the axis of said control shaft.

6. The system set forth in claim 1 in which a second adjustment sleeve is provided, said sleeve being rotatably mounted on an axis extending at right angles to said plate, said sleeve having a peripheral cam surface which is eccentric with respect to its mounting axis and which defines the support for the free end of said strip.

7. The system set forth in claim 1 in which a first adjustment sleeve is eccentrically mounted on said axis, said strip having an opening through which said sleeve extends to define the pivotal mount for said strip, a second adjustment sleeve is provided, said second sleeve being rotatably mounted on an axis extending at right angles to said plate, said second sleeve having a peripheral cam surface which is eccentric with respect to its mounting axis and which defines the support for the free end of said strip, said sleeves being adjustable to vary the position of the arcuate outer cam surface of said strip with respect to the axis of said control shaft.