A group of collated book signatures or other layers of paper are cut with bevel edged bits spaced around the circular periphery of a wheel by feeding the paper in the same direction as the teeth rotate such that an exposed side of the paper advances in a plane intersecting normal to the circular radius more than half an inch from the outer end of the radius, and such that the bevelled outer corner of the cutting edge enters through the paper plane first and with the edge inclined away from the paper plane at an angle of zero to 20.degree.. At its furthest penetration each cutting edge is inclined at less than 60.degree. to the cutting plane.
A cutting wheel for roughing the backbone of the collated leaves in an unbound book has a number of rough cutting teeth set around the periphery of a disk or like wheel body, each tooth having a cutting edge formed by a leading surface which is inclined radially inwardly and rearwardly with respect to disk rotation so that as the book is fed into the wheel each tooth cuts and partially detaches a series of tab like fragments along the backbone edge of each leaf and then twists the tabs with a tearing action. One or more raker teeth with raking edges slightly below the ends of the cutting teeth edges inclined oppositely to the cutting teeth twist the tabs with reverse twist tearing them from the leaves so as to leave a substantially continuous fibrous edge along the torn edge of the leaves.
A precision book cutting wheel with insertable cutting bits has sockets slidingly receiving the bits and a clamping block for holding the bit in adjusted position. The sockets are inclined at an angle of 20.degree. to 40.degree. to a cutting plane normal to the axis of the wheel, and each bit has an outer cutting edge formed by a bevel parallel to and adjustable to the cutting plane.
An apparatus for simultaneously trimming both lateral marginal portions of a scalloped stream of sheets has a transporting unit which is driven to advance the stream in a horizontal cutting plane flanked by two stationary counterknives which are mounted below the cutting plane and whose cutting portions are disposed in the cutting plane. The sheets in the cutting plane are biased against the transporting unit and their marginal portions are trimmed by the cutting edges of radial knives mounted on two coaxial rotary holders disposed at a level above the cutting plane and each cooperating with a different one of the counterknives. The cutting edges of the knives are inclined with reference to the longitudinal directions of the respective knives and orbit along endless paths which are intersected by the cutting plane so that each cutting edge which reaches the cutting plane moves below such plane before beginning to move upwardly and above the cutting plane. The cutting plane and the cutting edges make an angle of 0.degree.-15.degree. when the cutting edges reach the cutting plane, and the angle between the cutting plane and the cutting edges is 15.degree.-45.degree. when the respective knives extend at right angles to the cutting plane so that the cutting edges are disposed in the lowermost portions of their respective endless paths. The speed at which the cutting edges orbit greatly exceeds the speed of travel of sheets in the cutting plane.
A cutting wheel for roughing the backbone of the collated leaves in an unbound book has a number of rough cutting teeth set around the periphery of a disk or like wheel body, each tooth having a cutting edge formed by a leading surface which is inclined radially inwardly and rearwardly with respect to disk rotation so that as the book is fed into the wheel each tooth cuts and partially detaches a series of tab like fragments along the backbone edge of each leaf and then twists the tabs with a tearing action. One or more raker teeth with raking edges slightly below the ends of the cutting teeth edges inclined oppositely to the cutting teeth twist the tabs with reverse twist tearing them from the leaves so as to leave a substantially continuous fibrous edge along the torn edge of the leaves.
The backbones of successive stacks of signatures of a series of such stacks are trimmed by a rotary implement having two annuli of substantially radially extending orbiting trimming or cutting tools. The tools of one annulus extend radially outwardly beyond the tools of the other annulus, and the tools of one annulus extend axially forwardly beyond the tools of the other annulus. The tools which extend axially forwardly beyond the other tools orbit at a higher speed. The two annuli of tools can be orbited in the same direction or in opposite directions.
