The invention relates to a cutting device for cutting from a width of a foldable sheet material with a determined breadth sheets having respective beginning and end profiles extending over the breadth.

Such a cutting device is intended particularly for cutting from a width of endless cardboard sheets which are provided in the longitudinal direction of the width with crease lines in longitudinal direction, and which are provided on their end surfaces with crease lines in transverse direction for folding over end parts therealong which are bounded on their ends by respective beginning and end profiles.

It is known to cut sheets from endless cardboard using a cutting frame or stamp cutting knife which is pressed into the cardboard width to be cut.

In order to cut sheets from cardboard in such a manner relatively great forces have to be exerted on the cutting frame, for which purpose heavy cutting machines are required. The forces are transmitted by the constituent parts of the machine to the floor surface on which the machine is placed, which entails obvious drawbacks. The known cutting machines are moreover expensive, while rapid wear of the knives in the cutting 'frame quickly results in qualitatively less good cut edges in the sheets, and in relatively high operational costs.

It is an object of the invention to provide a cutting device of a relatively light construction with which intis possible to cut sheets from a width of endless sheet material, in particular cardboard, wherein the exerted forces are absorbed in the machine itself, and wherein problems of wear with cutting knives do not occur, or at least only in small measure.

It is a further object to provide a cutting device which is durable and relatively cheap to use.

These objectives are achieved with a cutting device of the type specified in the preamble, which according to the invention comprises a frame which is horizontal in operating situation for guiding a width of a foldable sheet material thereover in a determined transport direction, a stamp which can be placed above this frame and coupled to this frame and which is provided successively in the transport direction with knives corresponding with the beginning profile and the end profile, wherein the central surface of the stamp bounded by these knives corresponds to waste pieces for cutting out of the width, and the peripheral surfaces adjacent to the central surface correspond to respectively a beginning part and an end part of successive sheets, and a pressure roller suspended under and from this frame in a carriage and displaceable in contact with these knives, which carriage is coupled rigidly to the frame on a first side in axial direction of the pressure roller and coupled movably to the frame on an opposite second side in axial direction of the pressure roller.

In a cutting device according to the invention the sheets are cut from the width of sheet material by guiding this width over the frame, carrying the stamp with the knives onto the width and displacing the carriage with pressure roller along the underside of the width, wherein the pressure roller presses against the knives and the desired profile is thus formed on the end surfaces of the sheet for cutting. Because the stamp and the pressure roller are both coupled to the frame, the forces exerted by the stamp and the pressure roller are absorbed within the construction of the cutting device, inside the part of this construction in which the stamp and the pressure roller are arranged. Because the carriage is coupled rigidly to the frame on only one

side in axial direction, i. e. it is fixed, the occurrence of frictions in the suspension of the carriage, and thereby the occurrence of wear of the pressure roller and the knives and the ensuing reduced quality of the cut edges of the sheets for cutting, are prevented.

In one embodiment of a cutting device according to the invention the carriage is guided on its first side over a rail with a wedge-shaped cross-section.

In another embodiment the cutting device according to the invention is provided with a pneumatic drive for the carriage.

In an advantageous embodiment the cutting device is provided with a drive spindle for the carriage, wherein the carriage is preferably coupled to a spindle nut which is displaceable along the drive spindle and which is received for movement over a predetermined distance in directions transversely of the drive spindle in a housing coupled fixedly to the carriage.

In this latter embodiment, mechanical stresses possibly occurring in the construction cannot be transmitted to the carriage by the drive spindle as if there were a cardan joint between the carriage and the drive spindle.

In yet another embodiment the cutting device is provided with a belt of a flexible material tensioned horizontally by the carriage on either side of the pressure roller and round two reversing rollers extending parallel to the pressure roller for the purpose of providing a guide surface for a width of sheet material for guiding over the frame.

In a preferred embodiment of a cutting device according to the invention the pressure roller is at least provided with a surface layer of a plastic material on a basis of polychloroprene.

It has been found that a pressure roller with at least one surface covering of polychloroprene, a strong

and very wear-resistant plastic material known under the trade name of neoprene, can particularly withstand the repetitive load by the knives at the same position each time, without local crumbling of the material and ensuing formation of peripheral tracks in the pressure roller.

In a cutting device according to the invention the central surface of the stamp is preferably covered with a relatively poorly compressible material and the peripheral surfaces are covered with a relatively readily compressible material.

It has been found during cutting of sheets using a stamp covered in such a manner that the parts corresponding with the central surface to be removed from the width are compressed to form waste pieces easily removed from the stamp, while the end and beginning parts corresponding with respective peripheral surfaces also have their original thickness after cutting.

The central surface is for instance covered with a rubber with a determined first Shore value for the hardness, and the peripheral surfaces are covered with a rubber with a second Shore value for the hardness which is lower than the first Shore value.

So as to prevent wear of the pressure roller the device is provided in yet another embodiment with a flat plate between the knives and the displaceable pressure roller for the purpose of providing an indirect contact between the knives and the pressure roller.

The invention will be elucidated hereinbelow on the basis of embodiments and with reference to the drawings.

In the drawings Fig. 1 shows in cut-away perspective view a part of an embodiment of a cutting device according to the invention, Fig. 2 shows in perspective view a carriage with a pressure roller for the device shown in fig. 1, and

Fig. 3 is a front view of the carriage shown in fig. 2 in the operative situation.

Corresponding components are designated in the figures with the same reference numerals.

Fig. 1 shows a part of a cutting device 1 in a schematically represented cutting and folding line 2 for endless cardboard. Shown are a horizontal frame 3 over which the cardboard for cutting is guided, and an auxiliary frame 4 which is coupled fixedly to this frame and in which a stamp 5 is mounted. Stamp 5 is pivotable relative to auxiliary frame 4 and is shown in folded- open position. Stamp 5 is provided with knives (not shown), wherein the central surface 6 of stamp 5 bounded by these knives corresponds to waste pieces to be cut from the width of cardboard, and the peripheral surfaces 7 adjacent to central surface 6 correspond to respectively an end part and a beginning part of successive sheets. The central surface 6 is covered with a layer of a hard rubber, the peripheral surfaces 7 are covered with a soft rubber type. The central surface 6 corresponds to waste pieces to be cut out, the peripheral surfaces 7 on the left in the drawing correspond to the end parts of a first packaging for cutting, the peripheral surfaces 7'on the right in the drawing (with the shown transporting direction 8 upstream of the peripheral surfaces 7 on the left) correspond to the end parts of a second packaging for cutting. Stamp 5 can be folded down and connected fixedly to auxiliary frame 4 on fixing supports 9, in which situation the knives of stamp 5 extend downward to a position just above the surface of a width of cardboard to be cut. Further coupled to auxiliary frame 4 is a frame 10 with four rotatable discs 11 for arranging crease lines in longitudinal direction in the width of cardboard. In order to arrange crease lines in transverse direction suitable pressing elements are arranged at the locations suitable for the purpose in

stamp 5. These pressing elements are metal strips similar to the knives, albeit without sharp cutting edge.

Fig. 2 shows a carriage 13 in which a pressure roller 14 is suspended. In the operative situation the carriage 13 is coupled to frame 3, wherein carriage 13 is fixed on its left-hand side in axial direction of pressure roller 14 (shown in fig. 3) and is guided on the right-hand side 15 on cylindrical wheels 16 over a rail (shown in fig. 3) with a rectangular cross-section such that carriage 13 is movable on its right-hand side 15 in axial direction of pressure roller 14. Carriage 13 is displaceable in transverse direction 12 of the cardboard width in a manner such that the pressure roller 14 is displaceable in transverse direction 12 of the cardboard width under frame 3 and in contact with the knives of stamp 5 (in folded-down position).

Fig. 3 is a front view in operative situation of the carriage 13 shown in fig. 2. Carriage 13 is suspended on its right-hand side 15 with cylindrical wheels 16 from a rail 17 of rectangular cross-section which is mounted on an element 18 coupled to frame 3 of the cutting device, is suspended on its left 24 upper side with wheels 19 provided with a V-shaped groove 23 which co-act with a rail 21 which has a wedge-shaped cross-section on its upper side, wherein cylindrical wheels 16 co-act with the flat underside of rail 21 which is mounted on an element 22 coupled to frame 3 of the cutting device.