GB2159453A

GB2159453A - Apparatus for cutting sheets

Info

Publication number: GB2159453A
Application number: GB08513162A
Authority: GB
Inventors: Esa Paananen
Original assignee: ARTJERVEN METALLI Oy
Current assignee: ARTJERVEN METALLI Oy
Priority date: 1984-05-30
Filing date: 1985-05-24
Publication date: 1985-12-04
Also published as: SE8502642D0; GB2159453B; FI842155A; FI71083B; FI71083C; GB8513162D0; FI842155A0; DE3518148A1; SE8502642L

Abstract

The apparatus, particularly for cutting long steel sheets in their longitudinal direction, which comprises a table (2) for carrying a sheet (3) to be cut and a cutting unit (1) associated with the table and provided with rotary cutters (4,5). To enable the apparatus to cut arbitrarily long steel sheets, the cutting unit (1), which is adapted to be movable along the side of table (2) upon guide rails (21,22), is provided with disc-shaped cutters (4,5) respectively above and below a gap (16) arranged to receive the edge of a sheet, the cutters being mounted on shafts (6 and 7), journalled in cutting unit (1) and extending above and below gap (16) so as to engage with mechanically rotatable transmission means (10,9,8). The motor driving the means 8-10 also, via a sprocket & chain, moves the cutting unit lengthwise of the table. <IMAGE>

Description

SPECIFICATION Apparatus for cutting sheets The present invention relates to an apparatus for cutting sheets, particularly for cutting long steel sheets in their longitudinal direction, said apparatus being of the type comprising a table for carrying a sheet to be cut and a cutting unit associated with the table, the cutting unit being displaceable on guide rails lengthwise of the table and being provided with disc-shaped rotary cutting blades or cutters above and below a sheet to be cut and being mounted on shafts which are journalled in the cutting unit, the shafts extending above and below the plane of a sheet to be cut, and the shafts being in engagement with mechanically rotatable transmission means.

Equipment of this type has been earlier used as thin sheet cutters, as set forth e.g. in US Patent Specifications Nos. 4,346,635 and 2,777,521. In those specifications, a continuous band of sheet is pulled over a certain distance onto a cutting table, whereafter a cutting unit movable above the table travels an equal distance and cuts or shears the sheet into strips of a certain width. These prior art mechanisms include several drawbacks and limitations. They can only be applied to cutting strips of equal widths. Also the possibilities of adjusting the width of such strips are quite limited and the same goes for the widths of sheets to be worked on. The sheets to be cut must be flat, i.e. there must not be folded edges or attached projections.The apparatus is only capable of cutting in one direction, so an unloaded return stroke is required (during which a band to be cut is shifted forward). In practice, these prior art mechanisms cannot be applied to cutting thicker sheets. If there is a rather narrow strip to be cut at the fringe of a thicker sheet, the cutting must be effected in two steps (first through part of the sheet thickness and then through the remainder) to avoid distortion of the strip. This capability of two-step cutting is not possessed by equipment intended for the production of strips or stripes from bands of thin sheet. In the prior art sheet cutters or guillotines, used in engineering workshops and capable of cutting or shearing also wedge-shaped and thick steel sheets, the length of a cutting edge matches the length to be sheared.

Such mechanisms are highly robust in design, heavy and expensive. Despite that, their cutting length is limited, so that only the heaviest and most expensive guillotines are capable of cutting standard sheets in longitudinal direction.

It is an object of the present invention to provide an apparatus of the above-mentioned type for cutting sheets, wherein the above drawbacks and limitations are mitigated or avoided.

According to the present invention then, in apparatus of the type described, the cutters are mounted adjacent to the side edge of the table and the cutting unit, positioned substantially beyond the side edge of table and leaving the space above the table unoccupied, is provided with a gap open at its side facing the table, said gap constituting a lateral extension of the supporting table top on the side of the cutters opposite to the table for receiving and passing therethrough a strip to be cut off a sheet.

The invention will now be further described by way of example with reference to the accompanying drawings, in which: Figure 1 shows an apparatus of the invention in cross-section, Figure 2 is a plan view of the cutting unit forming a part of the apparatus, Figure 3 is a diagrammatic plan view of the cutting table of the apparatus to a smaller scale, and Figure 4 shows a detail of the cutting in axial section of the table.

The apparatus is provided with a cutting unit 1 and an arbitrarily long cutting table 2, fitted with guide rails 21 and 22 on which the cutting unit 1 is mounted by means of rollers 18, 19, 20 so as to be displaceable along the side of table 2. As shown in Figures 1 and 2, the cutting unit 1 is mounted on table 2 by means of rollers 18, 19 on a levershaped support frame to be carried by guide rails 21, 22 fixed below said table 2, so that rollers 18 which are a distance away from cutting unit 1 roll along the underside of guide rail 21, and while roll 19, which is nearer to cutting unit 1, rolls along the top surface of guide rail 22.

The cutting unit 1 is provided with disc-shaped cutters 4 and 5, whose cutting edges are tangential to or touch each other in a proper fashion for shearing a sheet 3 therebetween. Cutters 4 and 5 are mounted on shafts 6 and 7 respectively which are journalled in bearings 12, 14 and 14; 15 respectively in the frame of cutting unit 1 between side plates 17. Bearing 12 is a special one as mentioned hereafter. Between shafts 6 and 7 is a gap 16 defined by a U-shaped guard for receiving the edge of a sheet 3 to be sheared. In the present case, the horizontal width of gap 16 is of the same order as that of table 2.

Mounted on the ends of shafts 6 and 7 are intermeshed gears 8, the lower gear 8 being meshed with a gear 9 at the end of a transmission shaft 10.

Transmission shaft 10 is fitted with a sliding clutch 11. Shaft 10 is rotated by means of a drive motor 36 (Figure 2), the same drive motor 36 being also adapted to drive a sprocket 37 which is meshed with a chain or a rack (not shown), extending lengthwise of the table but being fixed in its longitudinal direction. By means of sheaves 38, said chain is guided approximately half a turn around sprocket 37. During the rotation of sprocket 37, the entire cutting unit 1 travels lengthwise of the table and, at the same time, cutters 4 and 5 rotate at a rate matching the travelling speed of cutting unit 1.

Sliding or safety clutch 11 prevents the feed movement of cutting unit 1 if cutters 4 and 5 are incapable of shearing action.

To allow for different sheet thicknesses, the distance between axes of cutters 4 and 5 must be adjustable. Therefore, cutter 4 is journalled on its shaft 6 by means of a clearance bearing 12, fitted with a clearance adjustment screw (not shown). A screw 13 is provided to regulate the counter force exerted by cutter 4 to take up the radial cutting pressure which tends to urge the gap 16 open.

Since, during the cutting operation, sheets 3 must be firmly fixed to the table 2, it is provided at short lengthwise intervals with magnetic anchoring elements 23. If the apparatus is used to cut sheets which cannot be held magnetically, such as plastic sheets, elements 23 may be vacuum-operated anchoring elements.

On the other hand, long and heavy sheets must be placed in position prior to cutting. Therefore, the table is provided with rollers 25 or balls that can be raised and lowered above and below the table top, said table top being provided with openings 24 for and aligned with such rollers or balls.

In order to lift and lower the rollers or balls, the table is provided with the mechanism shown in Figure 4. A shaft 26 journalled to the frame is rotatable either by a hand wheel or mechanically, whereby angled levers 27 rotating with shaft 26 turn arms 29 around pivot points 28 for moving rods 30 in their longitudinal direction or longitudinally of the table. Bevelled faces of slide elements 31 mounted on rods 30 act to lift or lower the rollers 25 or the balls. A journal bearing 32 facilitates the pivoting of rollers 25 in a desired sheet conveying direction. If balls are used, said bearing 32 is of course unnecessary.

In order to avoid the necessity for separate measuring in positioning sheets on the table, the latter is provided with cross-wise adjustable limit stops 35, which are set by means of repeater motors 33 and set screws 34. The distance of limit stops 35 from the line of cutting can thus be set by means of a numerical set and/or display device. By adjusting the limit stops separately, a sheet can be positioned for cutting wedge-shaped pieces as well.

Claims

1. Apparatus for longitudinally cutting sheets, comprising a table for carrying a sheet to be cut and a cutting unit associated with the table, the cutting unit being displaceable on guide rails in the longitudinal direction of the table and being provided with disc-shaped rotary cutters arranged to be located above and below a sheet to be cut and being mounted on shafts which are journalled in the cutting unit, extend above and below the plane of a sheet to be cut and are connected a drive motor for rotatable transmission means wherein the cutters are mounted adjacent to the side edge of the table and the cutting unit, positioned substantially beyond the side edge of table and leaving the space above the table unoccupied, is provided with a gap open at its side facing the table, said gap constituting a lateral extension of the supporting table top on the side of the cutters opposite to the table for receiving and passing therethrough a strip to be cut off a sheet.

2. Apparatus as claimed in claim 1 wherein a sprocket, journalled in the cutting unit and in transmission engagement with a longitudinally fixed chain, rack or the like extending lengthwise of the table, is adapted to be driven by means of the same drive motor and transmission means are as provided for the cutters.

3. Apparatus as claimed in claim 1 or 2, wherein the transmission means comprise a shaft, parallel to said cutter shafts and fitted at its outer end with a gear meshed with other gears mounted on the outer ends of cutter shafts, the transmission shaft being connected through a sliding clutch to a sprocket for moving the cutting unit.

4. Apparatus as claimed in claim 1, 2 or 3, characterized in that one cutter has its shaft journalled by means of a clearance bearing provided with a clearance adjustment screw for shifting the cutter with respect to its shaft, control means being mounted between the clearance bearing and the frame of cutting unit for regulating the radial force acting against that one cutter.

5. Apparatus as claimed in any one of claims 1 to 4, wherein the cutter shafts and their transmission means are protected by a horizontal U-shaped guard, which defines said gap and has side plates, located either side of the U-shaped guard, are within the area of U-bottom designed to have a large surface area for taking up the forces directed on the cutters tending to urge said gap open.

6. Apparatus as claimed in any one of claims 1 to 5, wherein the cutting table is provided with rollers or balls adapted to be raised or lowered above and below the table top for feeding sheets to be cut, the table is provided with magnetic or pneumatic anchoring elements for holding a sheet stationary thereon during the cutting, and the table is provided with limit stops, adjustable cross-wise of the table by means of repeater motors (33), the distance of the stops from the line of cutting being settable by means of a numerical set and/or display device.

7. Apparatus as claimed in any one of claims 1 to 6, wherein the cutting unit is supported on the table by means of rollers in a lever-like supporting frame upon a pair of guide rails fixed below the table in such a manner that the rollers furthest away from cutting unit roll along the bottom surface of one guide rail while the roller closest to the cutting unit rolls along the top surface of the other guide rail.

8. Apparatus as claimed in any one of claims 1 to 7 wherein the horizontal dimension of the gap in a cross-wise direction of the table (2) is of the same order as the width of the table.

9. Apparatus for longitudinally cutting sheets substantially as herein described with reference to and as illustrated in the accompanying drawings.