During the manufacture of paper, paper is typically stored and transferred as rolls. When handling such rolls, it is extremely important to prevent any damage to the ends of the rolls. Even minor damage to the end of a paper roll denotes rejection of the entire roll since it can no longer be used in high-speed printing machines. The ends of paper rolls are typically protected with circular flaps cut from corrugated cardboard and placed against the end of a paper roll before placing a wrapping around the paper roll. At present, approximately twenty million end cover flaps of this type are used in Finland every year.

In the type of a cutting apparatus described in the introductory paragraph, a bandsaw is used as the cutting device. However, there are several restrictions and problems related to this kind of a cutting apparatus in which the pile of sheets is shaped into the form of a circular cylinder with a bandsaw. With a bandsaw, it is impossible to handle piles consisting of more than a few tens of corrugated cardboard layers since the cutting part of the blade cannot be made very large.

This is based first on the fact that the blade is made of a relatively thin metal band, as a result of which the blade easily bends leading to excessive variation in the shape and size of the flaps cut in case the cutting part is too large. Secondly, the moment of motion required from the saw blade naturally increases as the

thickness of the pile of sheets to be cut grows. Since only a relatively restricted moment of motion can be provided to the blade when using bandsaws, the thickness of the pile to be cut is limited to only a few tens of sheets at a time. The fact that only a small number of sheets can be cut at a time also means that the piles of sheets must be frequently changed, and in practise the cutting of end cover flaps with a bandsaw cutting apparatus is hard manual labour where the person in charge of the bandsaw must change the piles of sheets at a fast pace.

One further limitation to the bandsaw cutting apparatus is that too high a rate of sawing causes tearing of the edges of the flaps cut, as well as entangling of the edges of flaps one upon the other on the pile, leaving these flaps unsuitable for use in automatic wrapping machines of paper rolls in which the flaps are intended to be picked, one by one, by suction from the pile of end cover flaps. When applying this type of picking, the flaps in the pile of end cover flaps must not be entangled to each other since entangling would easily cause interruption in the function of the wrapping machine due to end cover flaps falling in the area between the picking point of end cover flaps and the paper roll.

The purpose of the present invention is to provide a novel cutting apparatus for eliminating the aforesaid problems related to bandsaw cutting apparatuses. The purpose is therefore to produce a cutting apparatus with none of the production restrictions described above nor any quality problems, which cutting apparatus when used will exclude any need for manual transfer or treatment of end cover flaps. This purpose is achieved with a cutting apparatus according to the invention, characterized in that the equipment for forcing the cutting blade to push into the pile of sheets by slashing consists of a feed drive for feeding the support rod so that the cutting blade proceeds in the direction of the axis of the pile of sheets, and that the cutting equipment further consist of a cutting and removal device placed after the blade in the slashing direction of the blade and supported by the support rod of the cutting blade, for cutting and removing the

sheet margin slashed off by the cutting blade from the pile, allowing the cutting blade to proceed over the pile of sheets by its own length thus allowing the cutting of the pile of sheets essentially into the shape of a circular cylinder.

The principle of a cutting apparatus according to the invention as described above is to utilize a slashing blade for cutting, which blade is vertically, in practise preferably from above, pressed into the rotating pile of sheets so that it cuts downwards layer by layer, shaping the pile of sheets into a circular cylinder. This method of cutting does not set any limits to the height of the pile of sheets to be cut. Typically, the corrugated cardboard sheets are piled to the cutting apparatus into piles of, for example, 450 sheets and the cutting apparatus according to the invention is very suitable for cutting a pile of this size at once. Since these types of piles of sheets are typically transferred on loading platforms by a truck or a pump cart or an equivalent vehicle, there is no need for manual handling of flaps separately or in smaller piles.

Preferably the cutting equipment of a cutting apparatus according to the invention further consists of a cutting and removal roll supported by the support rod of the cutting blade and placed after the blade in the slashing direction of the blade, for cutting and removing from the pile the sheet margin slashed off by the cutting blade. If the pile of sheets from which the flaps are to be cut is square and its side essentially equals the diameter of the desired flap, the only thing that is cut off the pile of sheets is in fact the corners of the squares, and in this case it is not necessary to separately take care of the removal of the off-cut margins. However, if the flap to be cut is smaller in its diameter than the side of the pile of sheets, it is necessary to remove the off-cut margin to allow the cutting blade to proceed. In practise, the cutting and removal roll has on its circumference rather short blades placed crosswise to the cutting direction of the cutting blade, which cut the off- cut margin at least from the points where it is narrowest. This type of a cutting

and removal roll does not require a separate rotating mechanism as long as it is pressed against the off-cut sheet margin with suitable force along with the support rod of the cutting blade, since this way the rotating of the pile of sheets itself takes care of the rotating of the cutting and removal roll.

In the following, the cutting apparatus according to the invention is described in more detail with reference to the accompanying drawing which shows a schematic view of the structure of a cutting apparatus according to the invention.

In the drawing, a cutting apparatus according to the invention is shown when it is cutting essentially circular flaps 1 from a pile 3 formed from rectangular sheets 2 piled one upon the other. The pile of sheets 3 is placed on a rotatable support 4.

The support is rotated by means of a chain a cogged belt or corresponding transfer arrangement with an electric motor which again is fed with a suitable frequency converter which can be used for steplessly adjusting the rotating speed of the motor and thus also the rotating speed of the pile 3. This rotation drive is marked in the drawing with a reference number 6. After the pile of sheets 3 has been brought to the rotatable support 4, it is pressed against this support 4 with the help of a hydraulic or pneumatic cylinder 5 adjusted on the head of a rod 13 attached to a body 12. This cylinder 5 is accompanied with a circular disk 14 which is pressed against the pile of sheets with the cylinder 5. Between the cylinder 5 and the disk 14, a bearing 15 is fitted which enables the rotation of the disk 14 in relation to the cylinder 5 and thus the rod 13. With this arrangement. the pile of sheets 3 can be pressed against the support 4 as tightly as desired.

Now that the pile of sheets is pressed to its place, the cutting may be started by putting the pile of sheets in rotation around its vertical axis with the help of the rotation drive 6. Before the rotation drive is started, the cutting equipment 7 is transferred to a position where the cutting blade 8 is located above the topmost

sheet of the pile of sheets 3. As shown in the drawing, the cutting equipment consists of a slashing cutting blade 8 which may be either knife-like or disk-like, and a rod 9 supporting this cutting blade 8 which also enables the placing of the cutting blade to a desired distance from the axis of the pile of sheets 3 to adjust the size of the flaps that are cut correctly. Furthermore, the cutting equipment consists of a feed drive 10 with the help of which the rod 9, and along with it the cutting blade 8, can be transferred in the vertical direction along the body 12 so that the cutting blade proceeds in the direction of the axis of the pile of sheets 3.

The feed drive 10 of the cutting blade consists of an electric motor and an frequency converter feeding it, which are used for moving the support rod 9 at a desired speed in the vertical direction of the body 12. Transmission of power can be accomplished by using, as with the rotation drive 6, a chain or a cogged belt.

When the cutting blade is at its upper position as described above, and the rotation drive 6 has set the pile of sheets 3 in rotation, the blade 8 is begun to be pressed into the pile of sheets 3 with the help of the feed drive 10 so that the rotation of the pile of sheets 3 and the feeding speed of the cutting blade 8 are cyncronized so that the cutting blade moves downwards for example by the thickness of one sheet during one rotation of the pile of sheets 3. Thus the cutting blade always slashes off the corners of a new sheet during each rotation of the pile of sheets 3, and no problems related to the too high feeding speed of the blade arise, for example the tearing of the slashed edges can be avoided.

If the diameter of the flaps to be cut is smaller than the side of the pile of sheets, the cutting blade cuts a pile of flaps in the shape of a circular cylinder around which a continuous margin or frame is left. It is precisely under such conditions, when the diameter of the flap to be cut is smaller than the side of the pile of sheets, when a separate device part for cutting and removing this sheet margin around the off-cut flap is needed. Without a removal device of this type, the

cutting blade can proceed into the pile of sheets only by its own length. In practise, it is therefore almost compulsory to include a cutting and removal device of sheet margins to the cutting apparatus since it, in the first hand guarantees the removal of the sheet margins and, on the second hand directs all the off-cut sheet margins to the same removal direction. As shown in the drawing, the removal device can consist of a cutting and removal roll 16 placed on the support of a support rod 9 after the cutting blade 8 on the slashing direction of the cutting blade 8. The cutting and removal roll includes a roll or disk 16 on the circumference of which rather short gripping and cutting blades 17 are placed crosswise to the slashing direction of the blade 8. Thus the blades are placed essentially to the radius direction of the flaps that are cut. The roll 16 does not require a separate running motor but the rotating motion of the pile of sheets 3 sets it in rotation and makes it push into the sheet margin cut, and slash into it rather short, crosswise slashes which when hitting the narrowest point of the off- cut sheet margin 11 or its proximity are enough to cut the sheet margin and to hurl this off-cut sheet margin in essentially tangential direction from the point of view of the rotating pile of sheets.

As concluded above, the cutting and removal roll 16 of the sheet margin does not require a separate running motor but it can be made to act as desired simply with the help of the rotation of the pile of sheets 3 when this removal roll moves downwards along the support rod 9. However, to produce some degree of flexibility between the removal roll and the support rod 9, it is possible to use, for example, a lever arrangement (not shown) where the rod supporting the cutting and removal roll is supported to the support rod 9 with a hydraulic or pneumatic cylinder. This way the cutting and removal roll can be pressed against the off-cut sheet margin with the desired force, and provide the support of the cutting and removal roll with a hydraulic or pneumatic set of springs in regard to the support rod 9. Above, a cutting apparatus according to the invention is described with the help of just one example-like embodiment and understandably several alterations can be made without deviating from the scope of protection defined by the accompanying claims.