Drive Means

Certain prior art drive means for flat, thin structures such as sheets, tapes and belts have all been designed so as to drive same without regard to the natural tendencies of the driven structure to wander in a horizontal plane as it passes through an opening between drive and idler rollers.

In devices where the horizontal wandering aforedescribed was a problem, it was the practice of the art to provide guide arms or pins on either and both sides of the driven structure to prevent it from wandering from the drive means. It was also the practice to provide the drive means with a variable axis to change the location of driving torque from the driving axis.

It is to the improvement of the aforesaid drive means by a design which limits (eliminates) horizontal wander that this invention has found utility.

More particularly, the drive means of this invention has as an object a drive which will use contact that varies along a horizontal plane in an oscillating fashion to impart motion to a flat, thin sheet, tape or belt such that any tendency of the latter to wander horizontally is negated.

A more specific statement of the object of this invention is to, in combination with an idler roller, disclose a heretofore unheard of drive roller whose drive surfaces are a returning spiral convolution having the form of a development of an elipse on an otherwise plain roller.

Another object of this invention is to form an idler roller from a plurality of discs that are rotatable relative to and independently of each other for supporting a flat, thin sheet, tape or belt with a helical drive means thereabove so that the drive means is operative upon the flat, thin sheet, tape or belt to cause separate discs to idle therewith.

The above description, as well as further objects, features and advantages of the present invention, will be more fully appreciated by reference to the following detailed description of a presently preferred, but nonetheless illustrative, embodiment in accordance with the present invention when taken in conjunction with the accompanying drawings wherein:

FIG. 1 is an isometric view of a drive means in accordance with this invention;

FIG. 2 is a side view along lines 2--2 of FIG. 1;

FIG. 3 is an end view of the drive means of FIG. 1; and

FIG. 4 is a partial plan view along lines 4--4 of FIG. 3 of a drive roller in accordance with this invention.

With more specific regard to FIG. 1, there is shown a flat, thin metal sheet 10 which is being driven in the direction of arrow 12 by means of a drive roller 14 rotatably driven by a shaft 16. As seen shaft 16 is supported by journal blocks 18 and 20 bolted to sides 22 and 24 of a housing or framework within which the drive means of this invention is desired.

As seen the drive for the shaft 16 may be by adapting a pulley 26 to the shaft beyond journal 20. A belt 28 between pulley 26 and another pulley 30 of a motor 32 will drive the shaft 16.

As can also be seen in FIG. 1, the sides 24 and 22 rotatably support a shaft 34 on which a support roller or an idler means 36, comprised of a plurality of low friction, as nylon discs 38, 40, 42, 44, 46, 48 and 50 (See FIG. 3), is held by end collars 52 and 54.

As is seen by the several views, the drive roller 14 of the drive means has a convoluted surface formed as a spiral extension or as a returned helix starting at one end 56 spiraling by means of a raised surface 58 to an opposite end 60, thence back by a spiral surface 62 to end 56. The pitch of the spiral or helical convolute is such as to locate ends 56 and 60 on opposite sides of roller 14. At the same time the path of surfaces 58 and 62 between the ends as well as the surface area A is such that the drive of sheet 10 is by line (point) contact that moves horizontally back and forth.

As can be seen in FIG. 3, the raised surfaces 58 and 62 on roller 14 have greater depth than the space between idler means 36 and roller 14 within which thin flat sheet, tape or belt 10 is located. Also sheet, etc. 10 is of a smaller cross section than the space in the form shown and is flexible to permit it to be pressed downwardly onto the discs 38, 40, 42, 44, 46, 48 and/or 50 progressively as the roller 14 rotates. As can be seen in FIG. 3, sheet, etc. 10 is compressing disc 50 and part of disc 48 due to surface 62 being rotated to drive sheet 10 in the direction of arrow 12. The discs, by being of nylon or other low friction material, permit the compression aforesaid and also permit a non-slip friction drive of the sheet, etc. 10. The edges of surfaces 58 and 62 may be slightly curved or radiused so as to preclude biting or otherwise damaging of the surface of the sheet, etc. Finally as the discs are not keyed to shaft 34, they will not rotate as true idlers until compressed slightly. Collars 52 and 54 serve only to constrain the discs in a horizontal plane without interfering with the relative movement possible between the discs.

While the operation of this invention is readily apparent from the foregoing description of the drawings, it would appear useful to restate it. In operation motor 32 is energized to drive, via belt 28, pulley 26 and thus shaft 16. This will rotate roller 14 clockwise (see arrow 64) to engage drive surface 62 with sheet 10 which may be an endless belt, and the latter on disc means 36.

During the continuous rotation of roller 14, different portions of its drive surfaces progressively engage with the surface 10. For example, if the roller 14 is initially engaged with the surface 10 at the start of its rotation, the point of driving engagement or contact between such roller and surface 10 will progress along the driving surface 62 toward the end 56. This will be in the direction of arrow 66 when the roller 14 rotates in the direction 64. Progressive driving contact then continues without interruption reversing in direction along the surface 58 toward the end 60 which is in a direction opposite to the arrow 66.

This cyclical movement continues without interruption to apply countering forces to the surface 10 that are transverse to the direction of its movement. Thus, if the surface 10 is part of an endless belt, the surface 10 will be walked back and forth along opposite sides of a true center line of its direction of movement. This cyclical walking movement continues without interruption because the transverse driving forces cyclically change in direction and the forces applied in one transverse direction are equal and opposite to those applied in the opposite transverse direction during each cycle of rotation of the roller 14. Hence, even though the surface 10 tends to walk or be moved first in one direction transverse to its given path of movement and then back in the opposite direction transverse to its given path of movement, the essential path of movement of the belt or surface 10 is along a given path. This causes the surface 10 to track cyclically back and forth transverse to its direction of movement but in a resultant essentially straight path of travel.

During this driving movement each of the separate discs of the idler roller means 36, being independently rotatable relative to each other, forms a supporting surface against which the progressive changing driving force of the roller 14 is transmitted. Because the discs of the roller 36 are independent of each other and rotate independently of each other, they reduce what would otherwise be an unequal drag or resistance against the surface 10 that a full roller would generate. Thus, as each idler disc operates under the influence of the drive roller 14, it rotates at the same speed as the drive roller and moves at the same rate as the surface 10 above it and with which it is engaged. Where the surface 10 is part of a continuous loop belt it sometimes happens that one transverse side of the belt is longer than the other transverse side of the belt. Even in such event where such variance in length of the belt's circumference exists, this will not affect the linear direction of travel of the belt because of the independent rotation of the discs of the idler 36 and of the progressive driving engagement of the roller 14. Hence, the drive of the surface 10 is always straight and true. This is also true whether the belt 10 is convex or concave in contour in a direction that is transverse to its length. In such case the drive roller 14 and the engaging configuration of the roller 36 may be congruently and correspondingly shaped in the direction of their axis.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.