CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of German Patent Application No. 10 2006 013 221.1, filed Mar. 22, 2006. The disclosure of the above application is incorporated herein by reference.

FIELD

The present invention relates to a method for the cutting of paper products, wherein the paper products are trimmed at at least one side in a cutting apparatus.

BACKGROUND

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

A cutting process of the above-described type is generally known from the prior art and serves, for example, to trim the paper products coming from a printing machine at, for example, three sides to the desired format. The side trimming is carried out, for example, with rotary cutting knives which are fitted with individual blades and carry out the trimming against a counter knife. Cutting processes are also known, wherein two rotary cutting knives meshing with one another are used to cut the paper products.

Although the known cutting processes have proven themselves, the problem can occur when using rotary cutting knives as the cutting means, in particular on the cutting of very thick paper products such as catalogs, telephone books or the like, that the trimmed side of the paper product does not have the desired surface property due to cutting tracks.

SUMMARY

It is the object of the invention to provide a method for the cutting of paper products with which in particular thick paper products can be cut using rotary cutting knives such that a cut surface is created which is free of cutting tracks.

This object is satisfied in that, following the side trimming, the previously trimmed side of the paper products is ground to refine the cut surface. In accordance with the invention, a grinding process takes place following the cutting process in which the previously trimmed side of the paper products is initially ground only by so much until any cutting tracks still present are removed, for example by approximately 1/10 mm. Very thick paper products such as telephone books or the like can also be cut to a desired format by the cutting process in accordance with the invention using rotary cutting knives, with the products resulting from the process having an extremely uniform cut surface which is free of any cutting tracks.

The method in accordance with the invention is suitable for any type of paper products, for example magazines, stacks of magazines, catalogs, telephone books or also pressed or bundled stacks of single sheets.

Advantageous embodiments of the invention are described in the description, in the drawings and in the dependent claims.

In accordance with a first advantageous embodiment, the paper products are held in a pressed together state at the start of the cutting up to the end of the grinding, i.e. the paper products are pressed together continuously during cutting and grinding at least at the side at which they were previously trimmed. The pressing together can take place in an advantageous manner with the help of pressing bands which are already present on the cutting apparatus. An extremely high quality of the ground surface results from the grinding of the product sides in the pressed state, with the products not being able to be reorientated between cutting and grinding.

In accordance with a further embodiment of the invention, the paper products can be conveyed during the cutting. A relative movement between the product to be ground and the grinding device used hereby results during the grinding process, which increases the uniformity of the grinding, but also the processing speed. This can also be achieved in that the cutting and grinding devices are moved relative to the product.

In accordance with a further advantageous embodiment of the invention, the paper products are ground using a grinding wheel which is oriented slightly obliquely to the previously trimmed side of the paper product. It is ensured with this embodiment that the paper product can be moved into the grinding device without problem since the grinding wheel forms a conical inlet for the paper product due to its slightly oblique orientation.

It can be advantageous due to the fineness of the paper dust arising for an extraction of grinding dust to take place during the grinding.

In accordance with a further aspect of the invention, this relates to a grinding apparatus comprising a conveying device with which paper products can be transported along a conveying path, with a pressing device being provided in the region of the conveying path with which the conveyed paper products are pressed together at at least one side during the transport. In accordance with the invention, a grinding device is provided in the region of the pressing device with which the paper products are ground in the region of the pressed together side.

Previously trimmed paper products can be ground off at their cut surface using the continuous grinding device in accordance with the invention such that a surface property is created which is free of grinding tracks. In this connection, it can be ensured with the help of the pressing device that the paper products, and also the individual sides of the paper products, are not displaced during the grinding process.

In accordance with an advantageous embodiment, the grinding device can have a grinding wheel which is oriented slightly obliquely to the conveying path so that it is ensured that the paper products can move securely into the grinding apparatus.

In accordance with a further advantageous embodiment, the grinding device has a grinding wheel which can be adjusted in the direction of the paper product to be ground, for example with the help of a spring, a motor, a positioning cylinder or the like. It is hereby ensured that no canting can occur on the moving of the paper product into the grinding device. At the same time, the depth of the grind can be influenced by the surface pressure and the pressing time.

In accordance with a further advantageous embodiment, the grinding device has at least two grinding wheels which are mounted on a changing device. The changing device can, for example, have a rotatable support on which the at least two grinding wheels are mounted so that, by rotation of the carrier, one of the grinding wheels can be brought into its working position and the other grinding wheel can be replaced and/or cleaned.

In accordance with a further advantageous embodiment, a cutting device is provided in front of the grinding device in the conveying direction with which the paper products are trimmed in the region of the pressed together side. In this embodiment, the grinding apparatus can simultaneously be used to carry out the edge trimming.

In accordance with a further advantageous embodiment, the grinding apparatus has a protective housing which prevents a spreading of grinding dust. The protective housing can be provided with a dust extraction.

In accordance with a further aspect of the present invention, this relates to a grinding tool for the carrying out of the method in accordance with the invention, with the grinding tool having a grinding disk on which a grinding wheel provided with holes is fastened by means of a clamping ring, with a plurality of elongate passages being provided in the grinding disk via which an extraction of grinding dust can take place.

Such a grinding tool is particularly suitable for the grinding of previously trimmed paper products since the grinding wheel can be replaced easily with the help of the clamping ring. Furthermore, generally known holes are provided in the grinding wheel so that extraction can take place through the grinding wheel. Due to the elongate passages in the grinding disk, a large-area extraction of the grinding dust is possible so that the spread of dust is minimized overall.

In accordance with a further advantageous embodiment, the passages can be curved in a plan view and can extend from a radially inner end to a radially outer end. In this manner, the rotation of the grinding wheel can also advantageously be used to convey the grinding dust arising within the passages with an elongate curve and, depending on the direction of rotation, to the radially inner end or to the radially outer end of the passages.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 is a sectional view of a grinding apparatus; and

FIG. 2 is a plan view of the grinding disk of the grinding apparatus of FIG. 1.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

FIG. 1 shows a section through a grinding apparatus which has a conveying device in the form of a belt pair 10, 11 which is driven by a drive device, not shown, and between which paper products P, for example telephone books or the like, can be transported along a conveying path. A pinch roller 12 and 14 is respectively provided beneath the lower transport belt 10 and above the upper transport belt 11 and is pressed in the direction of the paper product P via means which are not shown. The two pinch rollers 12 and 14 form a pressing device with which a side of the paper product P can be pressed together during the transport along the conveying path.

Furthermore, FIG. 1 shows a grinding device 20 which is provided in the region of the pressing device 12, 14 and with which the paper products P can be ground in the region of the pressed together product side. For this purpose, the grinding device 20 has a grinding wheel 22 which is shown by broken lines in FIG. 1 and which is clamped with the help of a clamping ring 24 to a grinding disk 26 which is screwed by means of screws 23 to a shaft 28 which can be driven via a motor which is not shown. The shaft 28 is supported on a base body 30 which can be moved on a carriage 34 with the help of an adjustment drive 32 such that the grinding wheel 22 can be positioned in the direction of the paper product P. A spindle 33 is set into rotation by actuating the adjustment drive 32 and in turns moves the base body 30 to the right or to the left in the vertical direction in FIG. 1. A control is provided in this process which always positions the grinding wheel 22 by a spacing of approximately 1/10 mm in the direction of the paper product P when the latter has passed the outer periphery of the grinding wheel 22 and is transported past the grinding wheel. The carriage 34 can subsequently be moved back again.

FIG. 2 shows a plan view of the grinding disk 26 of FIG. 1. As can be recognized, a total of twelve elongate passages 27 are provided in the grinding disk 26 in the embodiment shown which are each open toward the front side and rear side of the grinding disk 26 and through which an extraction of grinding dust can take place. The passages 27 are curved in a plan view and extend from a radially inner end A to a radially outer end B.

As FIG. 1 illustrates, the grinding disk 26 is connected via screws 25, which clamp the clamping ring, to an intermediate ring 29 in which a ring-shaped extraction passage 40 is provided which opens into a connected passage 42 for extraction. The intermediate ring seals with respect to components 36 and 38 fixed to the housing via a seal which is not shown and is accepted in a ring groove 44.

Since the grinding wheel 22 is provided with holes, the paper dust which arises during grinding can be extracted through the holes of the grinding wheel. For this purpose, underpressure is applied to the connected passage 42 so that the grinding dust moves through the holes of the grinding wheel 22 first into the elongate passages 27 of the grinding disk 26 and from there into the ring-shaped extraction passage 40 of the intermediate ring 29 before it is sucked into the connected passage 42. Since the grinding wheel 22 or the grinding disk 26 in FIG. 2 rotate counter clockwise, this rotary movement supports the transporting of the paper dust within the passages 27 in the direction of the outer end B. This contributes to a more uniform transporting away of the arising grinding dust being able to take place.

Alternatively, a dust extraction can also take place via a hollow shaft, with in this case the inner ends A of the passages 27 being guided into the interior of the hollow shaft and the direction of rotation of the grinding wheel being reversed.

Furthermore, the described grinding apparatus can be provided in a protective housing which additionally prevents a spreading of grinding dust.

The grinding apparatus in accordance with the invention, or the grinding device 30, is preferably integrated into a rotary cutting machine such as has been disclosed in German patent application 10 2005 001 471 of Jan. 12, 2005. The disclosure of this patent application is explicitly included by reference in the content of the present application.

In rotary cutting apparatus of this type, two rotary cutting knives meshing with one another are provided, with the paper products being pressed and guided between an upper and a lower transport belt. If the grinding device 30 in accordance with the invention is integrated into such a cutting apparatus, it can be advantageous to incline the grinding wheel 22 in FIG. 1 slightly around a vertical axis so that the grinding plane extends at a small acute angle to the previously trimmed side of the paper product P to form a product inlet.

In the method in accordance with the invention for the cutting and grinding of paper products, the individual paper products are trimmed at at least one side in a cutting apparatus such as is disclosed in the previously named German patent application 10 2005 001 471. After the trimming, the trimmed side remains held inside the pressing device and the paper product is led past the grinding apparatus 20 with the help of the conveyor belts 10, 11 such that, following the side trimming, the previously trimmed side can be ground to refine the cut surface. In this connection, the actuating motor 32 is controlled such that the grinding wheel 22 is briefly set on the paper product P led past. The paper product P is therefore both held in a pressed together state during the grinding and conveyed in the conveying direction during the grinding. At the same time, an extraction of the grinding dust through the previously described passages 27, 40 and 42 takes place during the grinding.

The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.