US2454863A - Web tension equalizing device - Google Patents

Description

Fatented ov. 3%, i9

Guy 3.

End i 1&1 New J rey F t- TENSION EQUALIZING DEVIGE Crocker, New Brunswick, N. 3., assor to Tape Corporation, a corporation of Application July 21,1945, Seriai No. coasts (This invention relates to apparatus for controlling the tensionof webs, for example paper, in the course of unwinding the web from a roll or winding it onto a roll. a

It is well known that flexible webs, such as paper, are dificult to wind and unwind uniformly and to keep straight and flat because the variations in the thickness, elasticity and other characteristics of the web causes the tension in the web to vary from time to time across the width of the web. This may cause the web to run crooked, wrinkle, bunch, sag, or tear unless some means is provided to keep the web under uniform tension across its width by counteracting the efiects of the variations. Numerous devices have been proposed for keeping the web under uniform tension, but those which have come to my attention are expensive or complicated to build and maintain or do not satisfactorily control the tension of the web.

It is one of the objects of my invention to provide an improved, simple and economical means for maintaining uniform tension across the width of a web being wound or unwound, or being passed through any desired machine for processing.

In the accompanying drawings,

Fig. i is a diagrammatic view in perspective of a portion of a web treating machine embodying my invention,

Fig. 2 is a section on the plane determined by the lines 2-2a, looking in the direction of the arrow, showing the parts in the position indicated in Fig. i, and

Fig. 3 is a corresponding section showing the parts in a difierent position.

Referring to the drawings, iii designates a web, for example of paper, which is being unwound connected to the pivots by two oflset arms at arfrom a supply roll i2 and is wound on a take-up roll it after being processed, as by being coated by a spreading knife it disposed between a pair of supporting rollers it. The take-up roll moves the web in the direction of the arrow in Fig. 1. After being coated at the spreading knife, the web is passed through any suitable drier, oven, or other desired processing apparatus it. The roll i2 is braked by any suitable form of brake, not shown, to prevent the web from unwinding too fast and to preserve the desired ten sion in the web.

In order to preserve a uniform tension across the width of the web, in spite of the tendency to vary the tension of increments across the width of the web, I provide a tension bar it of the form shown in Figs. 2 and 3 between the supply roll it and the first supporting roll it. As shown a Ciao. (c1. arr-2.1)

best in Fig. 3, the bar has a pair of aligned pivots it supported in any suitable fixed bearings 22 on the machine frame 23. The portion of the bar between the pivots is of z-form; that is, it includes a central straight sloping portion 2% ranged at 180 to each other. The center it of the straight central portion it lies on the axis til-30 of the pivots 2b. This axis is placed so that it will always be above the varying upper surface of the roll it from which the paper is unwound, the surface being represented by the dotted line it.

men operation is started, the tension bar is placed as shown in Figs. 1 and 2, so that the portion between the pivots .lies in a horizontal plane and the paper is fed across the bar and through the machine. As long as the paper remains uniform and straight and the tension of the two edges of the web is the same, the bar remains in the position shown in Fig. 2 and the paper drags across it; However, just as soon as the tension on one side of the paper, for example the left, shown in Fig. 3, becomes less than the tension on the other side of the web, the

.high tension side pushes down its end than? central portion 243, rotating the bar from the fiat position shown in Fig. 2 to some sloping position asindicated in Fig. 3. The bar is rotated by the web until the rising and i'ailingends oi the sloping portion to equalize the tension between the sides oi the web. It the difierence between the tension on the sides increases the bar is rotated still further, its maximum position of correction being shown in Fig. 3 with the arms 2i? at right angles to the line of travel of the web. An decrease in the difference of tension between. the two sides automatically moves the bartoward the fiat position until the tension again becomes equal.

n will be noted that the centerat or? the bar remains in the axis of rotation, the bar in effect having two arms 2E and 250 which simultaneously move toward and away from the web as the diiierence in tension varies.

The bar may be made of any suitable material, for example hardened and polished steel, or glass. The bearings 22 are of any mourn suitable type which will reduce friction to a minimum. The entirearrangement is simple and inexpensive and operates automatically without any attention on the part of an operator to preserve uniform tension across the width of the web.

While the device has been illustrated as applied to a web moving in a horizontal plane, it

is equally adaptable to webs moving in a vertical plane or in any desired direction, the rod being balanced in its bearings and not dependent upon gravity but being operated solely by the pressure of the paper in contact with the rod.

I claim as my invention:

1. Tension control apparatus comprising in combination means-for moving a web in the direction of its length and an elongated tension regulating member pivoted on an axis transverse to the length of the web and parallel to the normal plane of the web and adapted to contact the web along the length of the member, an intermediate point of said member being in the axis of the member and the member having a portion on one side of said point adapted to move in the direction toward the web when tension on one side of the web decreases, and havinga portion on the other side of said point adapted simultaneously to move in the direction away from the web.

2. Tension control apparatus comprising in combination means for moving a. web in the direction of its length and a tension regulating bar adapted to extend across the web and pivoted for rotation on an axis transverse to the length of the web and parallel to the normal plane of the web, the bar having a portion between the pivots .adapted to contact the web along the length of said portion, said portion being inclined to the axis and extending on opposite sides of the axis.

3. Tension control. apparatus comprising in combination means for moving a web in the direction of its length and a tension bar adapted to contact the web across the width of the web and pivoted on an axis parallel to the normal plane of the Web, the bar being rotatable on its axis in response to variation or tension on opposite edges of the web, the portion of the bar in contact with the web being inclined to the pivot axis whereby rotation of the bar about its axis by the web inclines said portion of the bar to the normal plane of the web.

4. Tension control apparatus comprising in combination means for moving a web in the direction of its length and a tension bar adapted to contact the web across the width of the web and pivoted on an axis parallel to the normal plane of the web, the bar being rotatable on its axis in response to variation of tension on opposite edges of the web, the portion of the bar in contact with the web being inclined to the pivot axis and extending on opposite sides of the axis whereby rotation of the bar about its axis by the web inclines said portion with respect to the normal plane of the web.

5. Tension control apparatus comprising in combination means for moving a web in the direction of its length and a tension bar adapted to contact the web across the width of the web and pivoted on a fixed axis parallel to the normal plane of the web, the bar being rotatable on its axis in response to variation of tension on oppo-v site edges of the web, the portion of the bar in contact with the web being inclined to the pivot axis whereby rotation of the bar about its axis by the web inclines said portion with respect to the normal plane of the web.

6. Tension control apparatus aomprlsing in combination means for moving a web int e direction of its length and a tension bar ad pted to contact the web across the width of the eb and pivoted on an axis disposed across the web, the bar being rotatable on its axis in response to variation of tension on opposite edges of the web, the portion of the bar midway between the edges of the web coinciding with the axis of the bar and the portion of the bar contacting the web being inclined in opposite directions from the axis whereby rotation of the bar about its axis inclines said last mentioned portion with respect to the normal plane of the web.

7. Tension control apparatus comprising in combination means for moving a web in the direction of its length and a tension bar adapted to contact the web across the width of the web and pivoted on an axis disposed across the web, the bar being rotatable on its axis in response to V variation of tension on opposite edges of the web,

the portion of the bar midway between the edges of the web coinciding with the axis of the bar,

the portion of the bar adapted to contact the web on one side of said midway point being inclined to the axis in the direction of motion of the web and the contacting portion on the opposite side of said midway point being inclined to the axis away from the direction of motion of the web.

8. Tension control apparatus for webs comprising in combination means for moving a web in the direction of its length, a Z-s'naped bar disposed in a plane and adapted to contact the web across the width of the web, the bar being pivoted on a longitudinal axis for rotation with variations in the tension of the opposite edges of the web, the portion of the bar on one side of the center of the web being inclined to the axis in the direction of travel of the web and the portion of the bar on the other side of the center of the web being inclined to the axis opposite to the direction of travel of the web whereby rotation of the bar will move the bar toward the normal plane of the web on one side of the center of the web and away from the normal plane of the web on'the other side of the center of the web.

GUY J. CROCKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Date

Images