Title: Device for spacing rollers

The present invention relates to a device for adjusting the gap between two or more rollers. More especially the invention relates to a device for adjusting the gap between a flexible die on a magnetic cylinder and an anvil cylinder on a cutting station or rotary press.

Cutting stations such as rotary press cutting stations have a flexible die in the form of a sheet which is wrapped around a rotating magnetic roller or cylinder, and an anvil roller or cylinder which co-rotates with the flexible die. Material to be cut or worked on, such as paper, label stock or film, is passed between the rotating flexible die and anvil cylinder. The gap between the flexible die or cutting shim and the surface of the anvil cylinder needs to be set accurately. If the gap is too narrow, the cutting blades on the flexible die can be damaged or wear out. If the gap is too wide, the material is not cut or worked on properly.

A particular problem arises when forming one or more perforation in materials such as paper using a conventional rotary cutting station. The flexible die has a number of perforating edges which pierce the material against the anvil roller to create the cuts or perforations in the material.

A problem with this is that the gap between the flexible die and the anvil cylinder has to be kept to within a very, fine tolerance. If the gap is too large the perforations are not formed properly. If the gap is too small, the perforating edges wear against the anvil roller.

It is know to provide a "gap setter" to help set the gap between a flexible die and anvil cylinder, but these are expensive, complicated, and frequently unreliable. Breakdowns often result in extensive down time whilst the gap setter is return to the manufacturer for repair . Another disadvantage of known gap setting devices is that they do not allow a specific, known size of gap to be set instead a process of trial and error is used which is slow and can lead to damage of the cutting blades.

The invention seeks to provide an improved device for adjusting the gap between a or flexible die and anvil cylinder. The device may also be used for adjusting the gap between any two or more rollers in applications other than rotary press cutting stations.

In a first aspect the present invention relates to a gap adjusting device for adjusting the gap between a pair of first and second rollers comprising at least one pair of spacing wheels or rollers adapted to engage and rotate with the circumference of the first roller and being connected to the second roller, and adjustable spacing means to adjust the distance between the or each pair of spacing wheels or rollers in use movement of the or each pair of spacing wheels or rollers apart by said adjustable spacing means causes the first and second rollers to move together, and movement of the or each pair of spacing wheels or rollers together by said adjustable spacing means causes the first and second rollers to move apart.

In a second aspect the present invention relates to a device, wherein the second roller is connected to the or each pair of spacing wheels or rollers through at least one radial bearing mounted on the axis of the second roller, each radial bearing having a circumference which engages with one of said pair of wheels or rollers, and each radial bearing allowing the second roller to rotate about its axis independently to the rotation of the bearing circumference.

In a further aspect the invention relates to a device, wherein two pairs of spacing wheels or rollers are provided adapted to engage with each end of the first roller, and a pair of radial bearings are provided one on each end of an axis of the second roller, and each radial bearing engages with a pair of wheels or rollers.

In a further aspect the invention relates to a device, wherein the or each pair of spacing wheels or rollers is supported in and projects from a housing, one spacing wheel of each pair being fixed to the housing and the other wheel being secured to the housing by a slider which slides relative to the housing thereby adjusting the distance between a pair of spacing wheels or rollers.

In a further aspect the invention relates to a device, wherein a sensor is provided to sense movement of the slider relative to the housing whereby to give a reading of the size of the gap between the first and second rollers.

In a further aspect the invention relates to a device, wherein the sensor is a linear transducer or a linear encoder.

In a further aspect the invention relates to a rotary press comprising the gap adjusting device wherein the first roller has a shim cutter and the second roller is an anvil cylinder.

In a further aspect the invention relates to a rotary cutting unit for creating cuts or perforations in material comprising: a first rotating cylinder with a plurality of perforating edges thereon and an anvil belt having a resilient surface adapted to co-rotate adjacent the first cylinder wherein in use the material to be cut or perforated passes through a gap between the cylinder and the belt, and the gap between the perforating edges and the belt is adjusted such that the each perforating edge penetrates the material to be cut or perforated and depresses the resilient surface of the belt as it enters the gap and the surface of the belt recovers as it rotates away from the cylinder.

In a further aspect the invention relates to a rotary cutting unit, wherein gap between the perforating edges and the belt is adjusted using the gap adjusting device.

In a further aspect the invention relates to a rotary cutting unit wherein the belt has a polyurethane surface.

In a further aspect the invention relates to a rotary cutting unit wherein the belt is supported to rotate around a main roller and a take up roller.

The invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a perspective view of part of a rotary press cutting station.

Figure 2 shows a perspective cut away view of part of Figure 1 with a pair of rollers in a housing moved together.

Figure 3 shows a perspective cut away view of part of Figure 1 with a pair of rollers in a housing moved apart.

Figure 4 shows a schematic perspective view of a part of a rotary cutting unit in use perforating paper or other material.

Figure 5 shows a cross section view of a flexible die on a magnetic cylinder and anvil belt.

Figure 6 shows a plan of the detail of the gap setting device.

Figure 7 shows a cross section view along the line A-A of the gap setting device shown in figure

6.

Figure 8 shows a cross section view along the line B-B of the gap setting device shown in figure

7.

Figure 9 shows a schematic perspective view of the gap setting device in contact with a pair of rollers.

FigurelO shows a side elevation of the detail of the gap setting device.

Figure 11 shows the underside of the gap setting device.

Figure 12 shows a cross section view along the line C-C of the gap setting device shown in figure 10.

Referring to Figure 1 there is shown part of a rotary press cutting station 1 according to the present invention. Cutting station 1 has a frame 2 which supports for rotation a magnetic roller 3 with an outer cylindrical flexible die 4 which is set in a recess in the magnetic roller 3 between the ends of roller 3. Roller 3 with flexible die or shim 4 would normally be rotated by a motor or

the like. Adjacent and above flexible die 4 is an anvil roller 5 with a central axial shaft 5A. Anvil roller 5 is shorter than roller 3 with flexible die 4. Anvil roller 5 is supported to move up and down in a track 2 A at each end of roller 5.

A gap setting device 10 is provided at each end of rollers 3 and 5 for adjusting the gap "X" between flexible die 4 on roller 3 and anvil roller 5.

Each gap setting device 10 has a housing 11 secured to the frame 2 by bracket 12 which allows only horizontal movement of the housing 11. A pin on bracket 12 may slide in a slot in the housing 11 (not shown) to allow horizontal movement.

With reference to figure 2 and 9 the gap setting device 10 comprises a pair of spacing wheels 13, 14 adapted to engage and rotate with the circumference of the roller 3 on the end of roller 3. Spacer wheel 13 is fixed to the housing. Spacer wheel 14 is connected to a slider 15 which slides relative the housing 11 by rotation of a shaft 16. Shaft 16 acting on slider 15 acts as an adjustable spacing means to adjust the distance between the spacing wheels 13, 14.

Spacing wheels 13, 14 are connected to the anvil roller 5 by means of a radial bearing 17 which is mounted around anvil roller axial shaft 5 A. The outer circumference of radial bearing 17 sits on and engages the two spacing wheels 13, 14. Radial bearing 17 allows the anvil roller 5 to rotate about its axis independently to the rotation of the bearing 17 circumference.

As shown in Figure 2, if the two spacing wheels 13,14 are moved together the distance between the circumference of the magnetic roller 3 and hence the flexible die 4 and the circumference of the radial bearing is increased whereby the roller 3 with flexible die 4 and the anvil roller 5 move apart. This increases the gap "X" between the flexible die 4 and the anvil roller 5.

As shown in Figure 3, if the two spacing wheels 13,14 are moved apart the distance between the circumference of the flexible die 4 and the circumference of the radial bearing 17 is reduced whereby the roller 3 with flexible die 4 and the anvil roller 5 move together. This decreases the gap "X" between the flexible die 4 and the anvil roller 5.

The gap "X" between the rollers will be determined by the size of the two spacing wheels 13, 14 and the length of the shaft 16. Preferably the gap "X" ranges from 0-5mm. More preferably the gap "X" ranges from 0-3.2mm. Preferably the gap "X" size can be changed using the present invention in l-0.5μm increments.

It will be appreciated that whilst roller 3 with flexible die 4 are fixed to the frame 2, anvil roller 5 with radial bearings 17 rest on spacing wheels 13,14 under the influence of gravity and are supported to slide up and down in track 2 A of frame 2. A pressure device (not shown) may be provided to bias the anvil roller 5 and radial bearings 17 towards the spacing wheels 13, 14 in order to maintain the gap between the flexible die and anvil roller while cutting. This also ensures that any back lash is taken up within the system.

It will be appreciated that as the spacing wheel 14 moves towards and away from the spacing wheel 13, so housing 11 will slide relative to bracket 12 in order to maintain symmetry of the spacing wheels 13, 14 about the centre line between the magnetic and anvil rollers.

A sensor such as by way of example only a linear encoder, or a linear transducer 18 is provided to sense and measure movement of the slider 15 relative to the housing 11 whereby, with an appropriate circuit, it is able to give an exact reading of the gap between the flexible die 4 and the anvil roller 5.

In use of the rotary cutting press, the distance or gap between the flexible die and anvil roller can be set accurately depending on the size of the cutting blades on the shim. This saves wear of the flexible die. This also reduces the set up time of the machine as the distance or gap between the flexible die and anvil roller can be set to a known predetermined gap size depending on the application rather than by trial and error.

The gap setting device 10 of the invention can be retro-fitted to existing rotary press cutters. The device self aligns itself between the roller 3 with flexible die 4 and anvil roller 5 and simply needs bracket 12 to secure it to the frame 2.

Optionally the spacing wheels 13, 14 could be replaced by rollers or other adjustable means of separating the rollers.

With reference to figure 4 in a preferred embodiment of the present invention there is provided a rotary cutting unit for creating perforations in materials such as paper, label stock or film.

The rotary cutting unit comprises a first rotating cylinder 3 with a plurality of perforating edges 4 thereon and an anvil belt 10 having a resilient surface adapted to co-rotate adjacent the first cylinder.

The material to be cut or perforated 20 passes between the cylinder and the belt.

The gap between the perforating edges and the belt is adjusted such that the each perforating edge penetrates the material and depresses the resilient surface of the belt, as it enters the gap and the surface of the belt recovers as it rotates away from the cylinder.

The belt may have a polyurethane or like material resilient surface.

As shown in figure 5 the rotary cutting unit has a first rotating roller having a magnetic roller 2 with a flexible die 3 thereon in the form of a sheet which is placed around a rotating magnetic cylinder 2. Flexible die 3 has a plurality of rows of perforating edges 4 on its surface. The rotary cutting unit also has an anvil belt 10 having a resilient surface, e.g. with a polyurethane surface. Belt 10 is supported to rotate around a main roller 1 IA and a take up roller 1 IB. Belt 10 co- rotates adjacent the first magnetic cylinder 2 with flexible die 3 paper or other material 20 passes between the magnetic roller 2 with flexible die 3 and the belt 10.

In use the gap between the perforating edges 4 and the belt 10 is adjusted such that the each perforating edge penetrates the paper or other material and makes a depression 12 in the resilient surface of the belt as it enters the gap and the surface of the belt recovers as it rotates away from the cylinder 2. The perforating edges create one or more cuts or perforations 21 in the paper 20.

The belt 10 has a surface which is sufficiently hard to act as an anvil to allow the perforating edges to make one or more cuts or perforations in the paper or like material as it passes through the gap. The belt 10 surface is sufficiently elastic to allow the belt to return to its original shape even after being repeatedly deformed by the perforating edges.

Optionally the anvil belt forms a sleeve around a single roller rather than the resilient surface being supported between two rollers as shown 5.