US3372886A - Paper reel tension control - Google Patents

Description

March 12, 1968 J, J. M DONALD 3,

PAPER REEL TENSION CONTROL Fild May 18, 1966 39 32 39 7 mn mu. 7

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INVENTOR.

I John J. Mc Donald BY United States Patent Ofi ice 3,372,886 Patented Mar. 12, 1968 3,372,886 PAPER REEL TENSION CONTROL John J. McDonald, Park Ridge, N.J., assignor to R. Hoe & Co. Inc., New York, N.Y., a corporation of New York Filed May 18, 1966, Ser. No. 551,050 2 Claims. (Cl. 242-75.42)

ABSTRACT OF THE DISCLOSURE A device for controlling the tension in a paper web having a belt driven about an idler pulley and which is in contact with the periphery of a web roll. Means for exerting a force on the idler pulley in response to reac tions of a web tension sensor and in a direction substantially parallel to the belt course leading from the web roll, resulting in a change in belt tension and consequently a shift in belt pitchline. This in turn causes minute variations in the speed of thed riven belt to thereby vary the torque exerted by the belt on the web roll which ultimately affects the tension of the web.

This invention relates to improvements in paper reel tension controls, such as are commonly used in supplying paper webs to web printing machines.

It has been proposed to control web tension in response to a floating roller or other sensor by varying the speed of drive of the tension control belts. Controls of this type are apt to be critical in their operation or not sufficiently sensitive and rapid in their response, depending on the particular type of variable speed drive which is used and upon whether the paper roll drive is of a slipping type.

Accordingly, the variable speed belt controls which have been proposed have not made sufiicient improvement to justify their use with belt tensioning devices of the type shown, for example, in prior Patents 2,617,610; 2,682,027; 3,217,999 and 2,344,952, and in which driven belts carried in a movable frame are used to accelerate the new roll prior to splicing and tension it during the major part of the time it feeds the web to the printing machine. The conventional, and generally very satisfactory, control method used in such devices utilizes movement of the belt frame, varying both wrap and tension, to regulate the torque applied to the. paper roll. In practice, the speed of the driving belt may differ from that of the paper roll periphery by only a few feet per minute so that belt pulley speed control of the order of a fraction of one percent, or even finer, is needed. Having in mind the unavoidable eccentricity of the web rolls, and consequent fluctuation of paper roll peripheral speed, conditions may occur where the direction of slip reverses, with a theoretical corresponding reversal as between the tensioning of the belt courses.

' It is an object of the present invention to provide a tension belt speed control for paper roll reels, which is compatible with existing systems and permits obtaining better control with little or no increase in cost or complication of equipment.

A further object is to provide a belt speed control which is useable as a substitute for existing control systems and provides both a simpler control, but also a better one. I

While applicable to other types of arrangement, the invention will be described, for definiteness, with relation to a reel of the type disclosed in the above-mentioned patents. In such reels, the tension control is effected by pivotally moving an idler pulley mounting about the axis of another idler pulley, thereby varying both the angle of wrap on the paper roll and the belt tension. The moving idler pulley is spring-mounted so that the tension depends on several different factors and the direction of movement for controlling tension is the same as that for positioning the belt to follow the paper roll as it decreases in diameter. In the present control system, the instantaneous, fine control of tension is achieved by minutely varying the belt speed, the variation being achieved by varying the effective pitch line of the belt, as by varying the tensioning force on the move-able idler, but in a direction substantially at right angles to the belt positioning adjustment.

With the foregoing objects in mind, as well as others which will appear, the invention will now first be fully described with reference to the accompanying drawing, and the features forming the invention will then be pointed out in the appended claims.

In the drawing:

FIG. 1 is a schematic and diagrammatic side elevational view of a reel embodying the invention in a preferred form;

FIG. 2 is an enlarged view of part of FIG. 1, showing the tension belt arrangement and a modified control therefor; and

FIG. 3 is a diagrammatic enlarged view of the belt and drive pulley.

The reel structure generally is like that shown in the above-mentioned patents, to which reference may be made for details of construction which, in themselves, form no part of the present invention. Pedestal 1 supports the shaft 3 of spider 2 having three sets of arms for supporting paper rolls in the respective web-supply, expiring and preparation positions A, B and C. Paper roll 4, in the position A, is shown as supplying the web W to a printing machine (not shown), the web passing around the successive rollers 5 to 9. Roller 8 is a floating roller, rising and falling as the tension increases and decreases. Proper tension is maintained by controlling the action of belts 11, which run around pulleys 12, 13 and 14, and engage the periphery of paper roll 4 for exerting regulating torque thereon. Pulley 12 is supported on a fixed shaft and driven by the press at a surface speed slightly less than that of the printing cylinders (and web W), pulley 13 also rotates on a fixed axis but is idle, and idle pulley 14 is mounted for adjustment to vary the wrap of the belts 11 on the paper roll 4 and follow the roll as it decreases in diameter. The mounting comprises arms 15 swinging about the axis of pulleys 13, the pulleys 14 being pivotally carried at the lower ends of arms 16 which are pivotally attached to arms 15 at 17 and urged in belt tensioning direction by a tension spring means 18 (FIG. 1).

In the construction of the said prior patents, the upper ends of springs 18 are fixedly secured to arms 15, so that the spring tension and hence the belt tension are determined by the roll diameter and the position of arms 15, along with the angle of wrap of the belts on the paper roll. According to the present invention there is provided for the springs 18 an adjustable upper end attachfollower roller 21 which runs against cam 22, the rotary position of which is adjusted by the floating roller 8 through means indicated symbolically at 25, and which may be mechanical, electrical or hydraulic. Roller 8, acting as the tension sensor, drops in response to falling tension and rises in response to rising tension, effecting a corresponding angular adjustment of cam 22. Specifically, the means 25 may be .the same circuitry as shown in the above-mentioned prior patents for actuating motor M which controls the belt wrap, but applied to rotative adjustment of the cam.

The adjustment of motor M and arms 15 moved therebymay be transferred to the control of limit switch 27 (instead of the floating roller as in the prior arrangement), carried by an arm 15 and reading, through the belt, the position of the paper roll periphery with relation to the mounting for the pulley 14. As shown, connections 28 from switch 27 lead to a motor relay control 30 which supplies current from power lines L-l, L2, to .the motor M through lines 29, for causing the belts 11 to follow the roll 4 as it decreases in diameter. Where the geometry permits, adjustment of arms 15 may be omitted. Where provided, it may involve only one or two settings or may approximate a slow continuous movement, but, in either case, the adjustment of tensioning force on the idlers 14 is so rapid that it is not interfered with by any positioning movements of arms 15.

It will be noted that the movement of pulley 14 in swinging about pivot 17 is practically at right angles to the movement as arms 15 are adjusted, so that the two adjustments are substantially independent.

In the modification shown in FIG. 2, there is substituted for the spring 18 and cam 22, a pneumatic control comprising a pilot valve 31 adjusted by the floating roller through arm 32 and connected to valve box 33 by airlines 34, so that the supplying and exhausting of air to the cylinder 36 controls the tension on the belts. Cylinder 36 is attached at 37 to an arm 15 and at 38 to the upper end of arm 16, thus exerting a controlled tensioning force F on the pulley 14. Shop air may be supplied through connections 39 for operating this equipment, as the pressures required are not high.

FIG. 3 indicates schematically at r the radius of the pitch line of belt 11 as it goes around pulley 12. This radius determines the linear speed of travel of the belt as it passes around the pulley while a corresponding radius about the center of paper roll 4 determines the ratio between linear speed of the contacting belt surface and the linear speed of the belt in its straight courses. It will be apparent that shifting of belt pitchlines can disturb the action of prior reel tensions to a point where actual reversal of desired direction of drive of the belts on the paper roll can occur. In the system of the present invention, the shifting of pitchlines in response to tension variation is utilized to vary the torque and permits operation with little or no perceptible movement of the belt pulleys and practically instantaneous response to tension change at the sensor.

Assuming a web which is 60" wide and a web tension at the reel of 1 lb. per inch of width, these being reasonably typical figures, the Web exerts an average torque, under constant press speed conditions, of 60 pounds multiplied by the paper roll radius, tending to accelerate the paper roll. Belts 11 exert an opposing torque, averaging the same belt peripheral force on the paper roll, less whatever is required to overcome frictional factors and produce the slight acceleration involved in increasing angular velocity with decreasing diameter. The difference in belt tension on the two sides of drive pulley 12 (or paper roll 4) will be approximately 60 pounds over-all, or, where two 4" belts are used, about 30 pounds per belt and 7.5 pounds per inch of belt width. The speed in the tight course will, with belting of usual type, be about 0.2% higher than that in the slack course. Since the angle of wrap around drive pulley 12 is about 180, and

leather surface belts are used on a cast-iron pulley, there will ordinarily be no slip, while the belts will ordinarily slip on the paper roll when operating with a normal wrap angle, such as, for example, thirty or forty-five degrees.

By adjusting cam 22, the tension in springs 18 can be varied from about lbs. to about 400 lbs., varying the tension in the belt courses at pulley 14 accordingly. Thus the belt tensions can be varied from 100 lbs. and lbs. in the slack and tight sides, respectively, to 400 and 460 lbs., respectively. The full specified range of tension adjustment may correspond to only about a 2.0% change in belt length, or a movement of pulley 14 of only about an inch. Since the spring tension changes involved in controlling the web tension are small, the corresponding movements of pulley 14 are hardly noticeable and produce no appreciable change in the angle of wrap on the paper roll.

The change in belt pressure, per pound change of spring force on pulleys 14-, is only a small percentage of the existing pressure on the paper roll and causes only a correspondingly small percentage change in drive (braking) torque. The change in belt pressure, however, in making a correspondingly small percentage change in belt speed, due to shifting of the effective belt pitch-line, may produce a very large percentage change in the (slip) velocity between belts and paper roll. For example, if the speed of paper feed is 1000 ft./min. and the slip velocity is 1%, or 10 ft./min., a change of only /1o% in the belt speed will amount to 10% of the slip speed, and also 10% of the power transmitted from belts to paper roll. Assuming, by way of example, drive pulley diameter of six inches and belt thickness of five-sixteenth inch, a pitchline shift of 0.003 will amount to a speed change of ten percent of the slip speed. The adjustment in the tension difference, belt pressure and torque required to produce the indicated change in power transmitted are instantaneous and automatic.

Change of effective pitch line radius with given change in tension depends upon a number of factors, and principally the following: material and diameter of driving and driven pulleys or other elements (e.g., the paper roll); belt thickness; presence or absence of slip on surface of driver and driven elements; compressibility of belt (unit volume) and ability of belt to flow; homogeneity of belt and location of any comparatively inextensible layers. Once the system has been calibrated for use with a particular type of belt, it is ordinarily necessary only to continue to use the same belt (within usual commercial tolerances on the belt specifications).

What is claimed is:

1. A paper web roll tension control comprising an arm, driving and idle pulleys mounted on said arm, a belt supported and driven by said pulleys with a course having a wrap angle around the periphery of a paper web roll, a floating roller for sensing tension variations in the web, a valve connected to the floating roller and actuated in response to movement of said roller, a link connected at one end thereof to said floating roller and at the other end thereof to said valve for connecting said floating roller to said valve, a pneumatic cylinder mounted on said arm for exerting a regulable force on said idle pulley in a direction substantially parallel to the belt course leading from the web roll to said idle pulley, a source of air connected to said valve by airlines for supplying air to said cylinder when actuated by said valve, whereby the force exerted on said idle pulley causes a tensioning of the belt r'e's ulting in a shift of the belt pitchline which causes a variation in the torque exerted by the belt on the web roll.

2. A paper web roll tension control comprising an arm, driving and idle pulleys mounted on said arm, a belt supported and driven by said pulleys with a course having a wrap angle around the periphery of a paper web roll, a floating roller for sensing tension variations in the web, a rotatably mounted cam its rotary position being adjusted by said floating roller, means connecting said floating roller to said Cam for adjusting the rotary position of said cam, a spring connected at one end to said cam and at its other end to said idle pulley for exerting a force on said idle pulley in response to rotation of said cam in a direction substantially parallel to the belt course leading from the web roller to said idle pulley, whereby said force exerted on said idle pulley causes a tensioning of the belt resulting in a shift of the belt pitchline which causes variations in the torque exerted by the belt on the web roll.

References Cited UNITED STATES PATENTS FRANK I. COHEN, Primary Examiner. 10 N. L. MINTZ, Assistant Examiner.

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