A novel punch for employment in a machine utilizing a punch ring containing a number of spaced, radially-arrayed holes in which the punches are secured, with the punch ring being used in cooperative relation with a die ring employing a number of dies corresponding to the number of punches used. During synchronous rotation of the punch ring and the die ring, each punch interacts each time with a corresponding die, with this arrangement making it possible for the edges of a continuous roll of paper or the like destined to be used in a computer or other type of business machine to be rapidly and effectively punched. Although interacting punch and die arrangements are well known, in accordance with this invention I utilize punches that have novel domed heads, with this doming advantageously making it possible for the increment of paper about to be punched to be stretched such that at the time the punch actually enters the die, the stretched piece of paper tends to pop away from the rest of the paper the instant it is punched, thus greatly diminishing the chance of "hangers" being created, which would later tend to impair the action of the computer or business machine in which the paper is employed. The doming of the punches also serves the additional advantages of diminishing the chance that a new punch will be broken during its first encounter with its respective die, and minimizing the friction present between each die and punch combination during normal operation of the machine.

A single stroke punch apparatus includes positive removal by compressed air of workpiece slugs which adhere to the punch. A die plate has a series of bushing receiving features formed from two concentric diameters. The die plate has provision for introducing a flow of compressed air into each of the bushing receiving features. A support bushing is mounted in each of the bushing receiving features and has a surface for support of the workpiece which is elevated with respect to the die plate. A slug removal bushing is also mounted in the bushing receiving feature and is pressed into the wall of the support bushing opposite the workpiece supporting surface to form a seal. The wall of the bushing receiving feature, the support bushing, and the slug removal bushing define a passage for the compressed air such that the compressed air impinges upon the punch directly adjacent the end wall of the support bushing to positively remove the punch slug which is adhered to the punch. The slug removal bushing has a passage for disposal of the punch slugs to which a vacuum may be applied to enhance slug disposal.

A device for perforating a web or sheet of material, includes a rotatable male die carrier roll having at least one radially extending cylindrical bore opening into its outer periphery, and a male die holder comprising a hollow cylinder having an outer diameter substantially equal to the diameter of the bore and being removably located within the bore. The outer and inner cylindrical surfaces of the hollow cylinder are substantially smooth, and the cylinder has a through slit extending in a radial direction completely between such surfaces and completely between opposite ends thereof. And, means are provided for applying an external force against the cylinder for frictionally holding a male die member in place therewithin, the slit in the cylinder permitting it to yield to such force supplying means.

A punch assembly is provided for a rotary forms press, for punching holes in a sheet of paper or other material as the material travels between punch and die assemblies. The punch assembly is of the split ring type, and has a hub to be carried on a punch shaft and driven thereby. A split punch ring of multiple segments is provided, for mounting on the hub, with the segments being connected together. The punches are carried by the punch ring. There is a slip fit between the punch ring and the hub to allow movement between the punch ring and hub to accommodate minor repositioning of the punch ring and its punches as the punches enter holes of dies with which they will engage, with the slip fit allowing either rotary repositioning or axial repositioning. Clearance is provided to an enable a limited amount of axial repositioning.

A rotary press punch ring includes a collar mountable on a shaft of a rotary press and a plurality of punch ring segments, each of which carries a plurality of punches. The punch ring segments are removably and interchangeably attached to the collar so that several punches may be removed and replaced as a group by removing and replacing one of the punch ring segments.