GB2148771A - Rotary cutting machine - Google Patents

Abstract

A rotary cutting machine comprising a rotatable anvil 1 supported by a rigid frame, two or more cutters 12, 13, 14 supported by the frame and each rotatable about an axis extending parallel to the anvil, and an arrangement 3, 5, 6, 9, 15 for driving the cutters in synchronism with the anvil. The position of each cutter relative to the anvil is independently adjustable to determine the gap between the cutter and the anvil. The series of independently positionable cutters can be of solid section, with each cutter being relatively short and of small diameter. <IMAGE>

Description

SPECIFICATION Rotary cutting machine The present invention relates to rotary cutting machines.

Rotary cutting machines are known for cutting predetermined shapes from sheets of material such as paper. Such machines generally comprise a rotatable cutter having a cylindrical surface from which a blade defining the predetermined shape projects a short distance, and a rotatable anvil having a smooth cylindrical surface, the anvil and cutter being positioned with their axes of rotation parallel such that as the anvil and cutter rotate in synchronism a sheet of material placed between them is cut to the predetermined shape.

The gap between the tip of the cutter blade and the anvil is of course critical to the operation of the machine. If for example one is seeking to cut out adhesive labels of the type on which addresses are printed by computer equipment it is necessary to cut through an adhesive facing paper of a laminated sheet without cutting through a backing paper on which the facing paper and the labels cut therefrom are carried. As a further example, if one is seeking to cut out carton blanks it is necessary for the cutter to sever the sheet material being processed but not to bear against the anvil to the extent that the cutter and/or anvil are damaged.

In known rotary cutting machines the cutter blade/ anvil gap is determined by bearers supported at each end of the cutter and defining cylindrical surfaces which bear on the surface of the anvil. The bearers are ground to a suitable diameter which is slightly larger than the diameter of the cutter blades so that when the bearers are forced against the anvil by pressure screws acting on slidable cutter bearing housings a predetermined gap is defined between the cutter blades and the anvil. The cutter is directly driven by a gear meshing with a gear rotating with the anvil.

If the cutter is relatively short, for example only a few inches long, it can be made sufficiently rigid for the above described arrangement to work satisfactorily. With longer cutters however the forces applied to the cutter via the bearing housing, bearers and blades cause the cutter to bend. When this occurs the gap between the cutter blade and anvil increases towards the centre of the cutter. The anvil can be shaped so as to compensate for this effect but this increases the cost of the anvil and does not avoid the need for careful setting of the forces acting on the cutter.

Because of the above problems it has been difficult to produce a conventional type of rotary cutting machine with a long cutter.

British Patent No. 2 049 527 describes an arrangement in which an attempt is made to overcome the above problems by providing at least one sleeve intermediate the bearers at the ends of the cutter against which sleeve a pressure roller bears. The force applied by the roller can be adjusted so as to counteract the forces on the cutter which tend to cause it to bend. This arrangement however requires very careful setting up if the various forces applied to the cutter are to be accurately balanced out.

It is an object of the present invention to obviate or mitigate the above problems.

According to the present invention, there is provided a rotary cutting machine comprising a rotatable anvil supported by a rigid frame, at least two cutters supported by the frame and rotatable about axes parallel to the anvil, the cutters being spaced apart relative to each other in the direction of the rotation axis of the anvil, means for driving each of the cutters in synchronism with rotation of the anvil, and means for independently adjusting the position of each cutter relative to the anvil to determine the gap between the cutter and the anvil.

Preferably the driving means comprises at least one lay shaft extending parallel to the anvil rotation axis, the lay shaft or shafts engaging the anvil and the cutters.

By providing a series of independently positionable cutters which can be of solid section the individual cutters can be relatively short and of relatively small diameter. It is therefore not necessary to compensate for any bending of the cutters. In addition, a damaged or worn cutter can be easily replaced without having to touch any of the other cutters.

Two or more lay shafts may be provided, each driving at least two cutters.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a schematic perspective view of major components of an embodiment of the invention; and Fig. 2 illustrates the support structure for the cutter and lay shaft assembly shown in Fig. 1.

Referring to Fig. 1 an anvil 1 is supported on a shaft 2 to which a gear 3 is keyed. A lay shaft 4 extends parallel to the anvil axis and supports gears 5,6,7 and 8. Gear 5 meshes with gear 3 and gears 6, 7 and 8 mesh with intermediate gears 9, 10 and 11 respectively.

Three cutters 12, 13 and 14 are supported independently of each other in separate housings with their axes parallel to the anvil axis and the layshaft. Gears 15, 16 and 17 are keyed to the cutters and mesh with the intermediate gears 9, 10 and 11.

Thus when the anvil 1 is rotated each of the cutters 12, 13 and 14 also rotate, the circumferential speeds of the anvil and cutters being equal. Another layshaft 18 driving two further cutters (not shown) is provided, the further cutters being positioned so as to register with the spaces between cutters 12 and 13 and between cutters 13 and 14.

Each cutter supports a series of cutter blades defining a series of rectangular formations suitable for cutting out rectangular adhesive labels from a laminated sheet (not shown) which in operation passes around the anvil beneath the cutters. The illustrated arrangement can thus cut out five rows of labels from a single laminated sheet.

Referring now to Fig. 2, the support structure for the cutter 12 is illustrated, each of the cutters being similarly supported. The machine has a cast lower frame 19 which is substantially rigid. The frame also comprises an upper cross member 20. A bracket 21 is slidable along the cross member 20 and may be secured in any desired position relative thereto by a bolt 22. The bracket 21 supports a swing arm 23 on which gears 6 and 9 are mounted, the gear 6 being keyed to but slidable along the layshaft 4. The angular position of the swing arm can be adjusted by a clamp 24.

The cutter 12 is supported between two arms 25 only one of which is shown, the arms being mounted on a block 26 slidable in machine tool bed type slots 27 along the lower machine frame. The arms 25 are positioned relative to the block by a conventional machine tool type cam slide and wedge arrangement adjustable by means of a screw 28. Thus the cutter 12 can be positioned by sliding the block 26 to the desired position, adjusting the screw 28 to set the cutter-anvil gap as desired.

Drive for the cutter can then be provided by sliding the bracket 21 to the desired position, and adjusting the swing arm to engage the gears 9 and 15.

It will be appreciated that cutters of various types and sizes can be readily mounted in the machine as desired and that any damaged or worn cutter can be easily replaced. Furthermore, if the cutters do not require bearers running in contact with the anvil the whole width of the material can be used to form cut out labels. In addition, as the anvil/cutter gap is adjustable the same cutter can be used to cut a variety of material thicknesses.

The gear train linking the layshaft to the cutters may be provided with helical teeth so that perfect register between the different cutters can be achieved by adjustment of the position of the gear supporting swing arms in the direction parallel to the anvil axis.

Claims (4)

1. A rotary cutting machine comprising a rotatable anvil supported by a rigid frame, at least two cutters supported by the frame and rotatable about axes parallel to the anvil, the cutters being spaced apart relative to each other in the direction of the rotation axis of the anvil, means for driving each of the cutters in synchronism with rotation of the anvil, and means for independently adjusting the position of each cutter relative to the anvil to determine the gap between the cutter and the anvil.

2. A rotary cutting machine according to claim 1, wherein the driving means comprises at least one layshaft extending parallel to the anvil rotation axis, layshaft or shafts engaging the anvil and each of the cutters.

3. A rotary cutting machine according to claim 2, comprising at least two layshafts each driving at least two cutters.

4. A rotary cutting machine substantially as hereinbefore described with reference to the accompanying drawings.