Several (but not all) the pages and images are reproduced. Some of the images are large and will take time to load. Although the equipment designs may appear archaic, they were in fact the latest technology of the period: This is a good illustration of how technology has changed in the last 50 years.

A great deal of development work on the two-drum winder has been done in recent years. For one thing, it has been specialized by the addition of features designed specifically for handling a particular sheet. Furthermore, because most paper machine speeds have increased greatly, new problems inherent in high-speed operation have been encountered and solved. It is common practice to make processing equipment, such as winders and supercalenders, capable of running at speeds between two-and-a-half and three times paper machine speed to give the operators a chance to adjust slitters and splice breaks while still keeping up with the machine. Thus, many papers are now being wound at speeds of 4000 FPM and up. Increased speeds tend to turn minor annoyances into real obstacles. A condition which is troublesome at 600 FPM can be disastrous at 2000 FPM. For example, a bottom slitter shaft designed to run at 600 FPM can be given a static balance once and forgotten. One designed for 2000 or 3000 FPM presents an entirely different problem. It must he carefully dynamic-balanced to start with, and care-fully watched in the mill. It takes very little mishandling to spring it enough so that at high speeds it will vibrate sufficiently to damage the blades or to break the sheet. Since good edges are an essential in a finished roll, the slitter section of the winder is one- which has undergone a number of improvements.

Good slitting depends upon a variety of factors, the first of which, of course, is the keeping of slitter blades and bands in top-notch condition. One prime cause of difficulty in keeping the blades and bands sharp and properly set is a vibrating bottom slitter shaft. For this reason, we have eliminated the slitter shaft on many modern winders and have substituted individually motor-driven bottom bands. This not only eliminates the shaft with its tendency to whip, but also makes it a very simple matter to remove any one of the hands for sharpening.

Another requirement for good roll edges is that all of the rolls in the winder be in proper alignment. One roll out of line can cause serious difficulties with interweaving and centering the finished roll on its core. This, plus the increased speed required of the rolls, has led to the use of anti-friction bearings throughout. The tendency for a-plain bearing to wear oversize and thus allow misalignment has thereby been over-come.

A third requirement for good roll edges is a proper spreading device. On most winders this consists merely of a flexible bar which can be bent into a bow, but on, papers where it is important to prevent any possibility of scuffing the surface, we have frequently used a heavily crowned roll as a spreader. For this same reason, slitter guard boards have been replaced by rolls.

In the above, I have been referring to shear slitters only, but the same difficulties of blade condition, balance, and spreading apply equally well to score slitters. We are currently investigating the possibilities of an improved design of rider roll slitters. In the past, these have been objectionable chiefly because of the large amount of dust created. By redesigning the blade and mounting we can minimize the dust. One advantage of the rider slitter is, of course, that the problem of spreading is eliminated. Another important one is that the sheet is threaded and started full width, eliminating the necessity for handling individual strips. This last is particularly important on counter roll winders where many slits are made and the cycle is extremely fast.

Control of sheet tension in the finished roll is of vital importance. In a two-drum winder, tension is introduced into the sheet by means of three devices. First is the unwind stand brake; second, the differential between the speed of the two drums; and third, the tension obtained from a driven rider roll at the start. To make a satisfactory finished roll, the winder operator should have sensitive and convenient means for controlling each of these three factors.

There are a number of designs of unwind stand brakes in present use. Probably the most common is a drum with a strap or band wrapped around it. The tension in the brake band can be controlled either by means of a hand screw, or, if an air piston or a diaphragm is attached to one end of the band, the tensions can be controlled by means of a pressure regulator. This brake, although very common, is not ideal, particularly on fine papers. The reason is that the braking effect produced is not proportional to the tension applied to the strap. The brake is regenerative in the sense that a small load applied to the band is automatically built up by the rotation of the brake drum. This tends to make the brake grab and jerk.

To give more accurate control of the unwind stand tension, two newer designs have been developed. One is the disc brake in which a revolving disc of brake lining material is squeezed between two flat, water-cooled metal surfaces by means of pressure applied through an air-operated diaphragm. The second is a shoe-type brake in which the brake shoes are squeezed against a revolving brake drum by means of an air diaphragm. In either of these brakes the air pressure applied can be made directly proportional to the braking effect. There is no regenerative action if the design is correct. To make control of any of these brakes as convenient and simple as possible, a pressure regulator and gauge are placed in the operator's panel. Since the panel is located where the operator can see both the unwinding sheet and the roll which is forming on the drums, he can make whatever adjustments are necessary without moving from his normal position.

The major part of the tension which is developed in the finished roll of paper should be introduced by means of a differential in speed between the front and back winder drums. There are a number of drives which lend themselves to easy tension control, but the two most common are drives consisting either of vari-pitch V belts connecting the two drums or of two individual motors, each driving one drum. If the V belts are used, one drum, normally the front one, is driven by a D.C. motor and the back drum is driven by V belts off the motor inshaft. The V belt pitch-changer motor control is mounted on the operator's panel so that the adjustment is easy and convenient.

The double motor drive is one in which each drum has its individual D.C. motor. Rheostats in the field circuits of the motors and are mounted on the panel so that the operator can readily adjust the torque applied to each of the drums. With this arrangement, it is possible to go from a condition where both motors are putting in the same torque to one in which one of the motors is doing all the driving while the other is acting as a generator. Thus, any desired sheet tension can be achieved. Amp meters for each motor are mounted on the winder panel to give the operator a convenient means of checking the amount of tension introduced at this point.

Each of these drives has particular advantages depending upon the sheet to be wound and the type of roll desired, but the important point is that both allow for adjustment of the wind-up tension.

The third means of introducing tension into the roll is the driven rider roll. It is, of course, very desirable to have a driven rider roll down on the winding roll at the start. At this time, the roll of paper is so light in weight that it is difficult to introduce much tension by means of the winder drum because there is little traction. Two things affect the amount of tension introduced by a rider roll. The first is the driving torque. of the various possible ways to drive a rider roll, the most flexible and compact is a D.C. electric motor. Power readily is supplied by the main winder drive generator so that the speed ties in with that of the drums and the torque is adjustable. The torque control is a rheostat mounted in the operator's panel, and an amp meter indicates the tension being added to the winding roll.

The second factor which will control the effect of the rider roll is the amount of weight acting to press the rider roll down onto the roll of paper. The weighting of the roll is controlled by means of a large air cylinder mounted at the back of the winder or in the basement. An air-pressure regulator and a pressure gauge mounted in the operator's panel give complete control of weighting and, thus, a measure of the tension being added.

This flexibility of control is important since the rider roll will introduce a substantial percentage of the roll tension at the start, but this percentage will drop rapidly as the weight of the roll, and consequently its traction on the drums, builds up.

The winder described above is of the more or less conventional design. There are numerous variations of this design which have been developed for highly specialized applications. There are tissue and crepe wadding machines with multiple tape driven unwind stands and score slitters; book paper winders with center-winding drives on the core shafts; and others of less general interest. In addition, the "push button" equipment for shaft and roll handling has kept pace with the winder speeds so that the roll is ejected, the shaft pulled out, the rolls lowered or rolled onto conveyors or trucks, new cores threaded onto the shaft and the shaft rolled into starting position, all by air valves and push buttons.

The advances made in winder design during recent years have been in the direction of greater flexibility of control-with the result that high-quality rolls can be made to the most exacting specifications and in the direction of labor saving designs and devices which make possible greatly increased production without the slightest sacrifice of quality.