Rotary press cutters

Abstract: A rotary press cutter assembly comprising a generally cylindrical support (10), a flexible cutting die (12) having a cutting profile (24) thereon, means (24) for detachably securing at least a leading edge (16) of the die (12) on a radially outer surface of the support (10), magnetic strips (14) set in the surface of the support (10) to attract the die (12), and vacuum ports (26) provided in the surface for sucking cut out portions of material onto the die (12).

Description: Technical Field The invention relates to cutters for the production of envelope blanks and profiles from a sheet or continuous web of material. Background Art Traditionally solid rotary cutters have been used in the production of envelope blanks and profiles. Two rotary or web cutters are used to produce the side profiles of the envelope blank from a web of material and are separated on a common shaft in a machine by a further rotary or separating cutter which separates the web of material into individual envelope blanks. When a solid rotary cutter needs to be reground or replaced it is necessary to remove the complete assembly and, where regrinding is required, return the cutter to the manufacturer. This is time consuming and expensive. EP 312 422 discloses a rotary press cutter assembly having a central cylindrical core surrounded by a shell, and a flexible metallic cutting die held on the shell by magnetic attraction. This document is the basis of the preamble of claim 1. EP 277 268 discloses a rotary press cutter which also uses flexible metallic cutting dies. A die is retained in a seat on a cylindrical holder by being clamped at both ends. The Invention The invention provides a rotary press cutter assembly for producing envelope blanks and profiles from a sheet or continuous web of material, comprising: a generally cylindrical support; a flexible cutting die having a cutting profile thereon; magnetic strips set into the surface of the support to attract the die; and vacuum ports provided in the surface of the support for sucking cut out portions of material onto the die; CHARACTERIZED IN THAT means are provided for securing a leading edge only of the die to a radially outer surface of the support so that the remainder of the die is held against the radially outer surface of the support by magnetic attraction only. Such a die can quickly and inexpensively be changed or varied to a die of different profile. The profile need not only comprise the shape of an envelope side or end, but may include the outline of a complete blank, possibly having one or more windows. Thus the overall construction of the machine can be simplified, and particularly the length reduced. Even for a window cutter, it is sufficient for the leading edge only of the die to be secured to the support. If a portion of the material is not cut out, for example if there is to be no window, the vacuum ports need not be used. Otherwise, the ports are arranged to transport a cutout towards a receptable for waste. Drawings Figure 1 is a side elevation of a rotary support of a press cutter assembly according to the invention for a side profile of an envelope blank; Figure 2 is transverse cross section corresponding to Figure 1 with a flexible cutting die mounted in position; Figure 3 is a side view of the assembly corresponding to Figure 2; Figure 4 is a laid-out view of the flexible cutting die from Figure 2; Figure 5 is a side elevation of a rotary support showing the mounting of a cutter assembly according to the invention for separating continuous envelope profiles from a web of material into the individual envelope blanks; Figure 6 is a transverse cross section corresponding to Figure 5 showing the mounting of a flexible cutting die; Figure 7 is a view from the other side of the support of Figure 5; Figure 8 is a view of a flexible window die on a rotary support for a cutter assembly according to the invention; Figure 9 is a transverse cross section corresponding to Figure 8; and Figure 10 is a side view of an adaptor in Figure 8. Best Mode Figures 1 to 4 show an assembly which comprises a generally cylindrical rotary support 10 mounted on a shaft 11, and onto which is mounted a flexible cutting die 12 of spring steel. The die 12 is secured on the radial outer surface of the rotary support 10 by a screw 24 (Figure 2) and magnetic strips 14 which are set in recesses in the surface of the support 10. The die 12 is provided with end flanges 16,18 which are bent out of the plane of the die to sit in and against the side walls of an axial groove 20 formed in the radially outer surface of the support 10. The leading edge flange 16 is provided with through holes for screws 24 to engage threaded recesses in the groove 20. The trailing edge 18 is not secured, as the die is held in position by the magnetic strips 14. The support 10 is provided with air ports 26 in its radially outer surface which register with cooperating ports (not shown) in the die 12, and through which air can be sucked or blown along an axial duct 13 in the shaft 11 to assist in removal of material cut out. The die 12 has a profile 34 for a side of an envelope, and does not include any cut out. When the die 12 becomes worn, or a different envelope profile is required, the screws 24 are removed, and the die 12 is replaced. Figures 5 to 7 show an assembly for separating the continuous side profiles produced by two cutter assemblies as in Figures 1 to 4 into individual envelope blanks by cutting across the web of material. Thus the profile (not shown) is substantially parallel to the shaft 11, unlike the profile 34. The separating cutter assembly of Figures 5 to 7 is mounted in an envelope manufacturing machine to run in synchronisation with the side cutter assemblies of Figures 1 to 4, one side cutter assembly being mounted on each side of the machine in a specific relationship to the separating cutter assembly at a position determined by the design of the machine. Figures 8 to 10 show an adaptor 40 supporting a window die 52 extending around only a part of the circumference of the support 10. At the ends of the adaptor 40, assembly retention screws 41 serve to hold in place end plates 43 while the magnetic strips 14 are secured in place by the setting of an adhesive. A number of adaptors may be secured to the support 10, to extend up to around the full circumference, so that more than one window can be cut per revolution of the support 10.

Claims: A rotary press cutter assembly for producing envelope blanks and profiles from a sheet or continuous web of material, comprising: a generally cylindrical support (10); a flexible cutting die (12) having a cutting profile (34) thereon; magnetic strips (14) set into the surface of the support to attract the die; and vacuum ports (26) provided in the surface of the support for sucking cut out portions of material onto the die (12); CHARACTERIZED IN THAT means are provided for securing a leading edge only of the die to a radially outer surface of the support so that the remainder of the die is held against the radially outer surface of the support by magnetic attraction only. A rotary press cutter assembly according to claim 1 in which the die (12) extends around only a part of the circumference of the support (10), and is supported on an adaptor (40). A rotary press cutter assembly according to claim 1 in which the die (12) includes the outline of a complete envelope blank. A rotary press cutter assembly according to claim 3 in which the die (52) includes the outline of one or more windows.

Inventors: BILLSDON DONALD DAVID, FULLER ROY, BILLSDON, DONALD DAVID, FULLER, ROY
Applicants: MAGNAFLEX SYSTEMS LIMITED
Application year: 1992
Main classification: B26F1
IPC codes: B26F1, B26D7