Cutting device

A device for simultaneous three-sided trimming of products in a plurality of cutting stations includes a common upper knife carrier operable in a vertical motion, blades to be attached to the upper knife carrier for at least front edge trimming and top and bottom trimming of the products and a first drive for driving the upper knife carrier. A conveyor system has top-related and bottom-related pairs of conveyor belts for conveying the products through the cutting stations of the device and a second drive driving the conveyor system. The first and second drives are self-contained, mutually independent drives connected to one another by control units. The top-related and bottom-related pairs of conveyor belts of the conveyor system are each driven by self-contained, mutually independent, position-controlled drives.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority, under 35 U.S.C. § 119, of German Patent Application DE 10 2012 005 462.9, filed Mar. 20, 2012; the prior application is herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a device and a method for the simultaneous three-sided or tri-lateral trimming of products. The device includes a plurality of cutting stations with a common upper knife carrier which is operable in a vertical motion, at least blades for front edge trimming and for top and bottom trimming of the products to be attached to the upper knife carrier, a first drive driving the upper knife carrier, a conveyor system having top-related and bottom-related pairs of conveyor belts for conveying the products through the cutting stations of the device, and a second drive driving the conveyor system, in which the first and second drives are self-contained, mutually independent drives connected to one another by control units.

In the production of brochures, the products, which have been collated and stitched, are cut in a device constructed for three-sided trimming, for example a trimmer. That is carried out in the cutting stations for the trimming of the front edge and the top and/or bottom by using movable upper blades acting against fixed lower blades or cutting bars.

Such a trimmer is known from European Patent Application EP 1 152 310 A1. The trimmer has a common upper knife carrier which is operable in a vertical motion by a servomotor. The upper blades for the front edge trimming and for the top and bottom trimming are mounted on the upper knife carrier. The front edge trimming is carried out in a first cutting station and the top and bottom trimming in a second cutting station. The trimmer has a conveyor system for the products in order to convey the products to the cutting stations and to convey them therefrom. The process of the three-sided trimming is carried out in that case in individual steps. The conveyor system conveys the product to the first cutting station and stops the product in the exact position required. Then the front edge trimming is effected. Subsequently, the product is conveyed by the conveyor system to a second cutting station and stopped in the exact position required. Then top and bottom trimming is effected. Subsequently, the three-sided trimmed product is conveyed to a delivery tray. The conveyor system known from European Patent Application EP 1 152 310 A1 includes top-related and bottom-related pairs of belts between which the product is clamped in a force-locking manner. The pairs of belts in that case are driven through continuous drive shafts by an independent drive, for example by a servomotor. A force-locking connection is one which connects two elements together by force external to the elements, as opposed to a form-locking connection which is provided by the shapes of the elements themselves.

In order to adjust the cutting device to different product formats, the distance between the two pairs of belts also has to be adjusted to the respective product format. In order to facilitate that, moveable form-locking connections between drive shafts and the timing belt pulleys of the conveyor belts are provided. The form-locking connections are in the form of polygonal shafts or splined shafts and, due to the alternating load resulting from accelerating and decelerating the products, are subject to high wear. They can consequently become unserviceable and cause costly repairs. The conveyor belts themselves are also subject to wear and require regular replacement. Changing the conveyor belts requires a lot of work due to the continuous shafts which drive the two pairs of belts. Furthermore, the installation and removal of an additional processing device, for instance a center trimming device, also involves a lot of work.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a cutting device, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which assures reliable conveying of products and at the same time simple adaptation of the device to different product formats.

With the foregoing and other objects in view there is provided, in accordance with the invention, a device for the simultaneous three-sided or tri-lateral trimming of products, comprising a plurality of cutting stations. Moreover, the device has a common upper knife carrier which extends through the cutting stations. The upper knife carrier is operable in a vertical motion by using a first drive. At least the blades for front edge trimming and for top and bottom trimming are mounted on the upper knife carrier. The products are conveyed through the cutting stations of the device by a conveyor system having top-related and bottom-related pairs of conveyor belts. The drives for the vertical motion and the conveyor system are each implemented as self-contained mutually independent drives, and connected to one another by control devices.

The drive for the top-related and bottom-related pairs of conveyor belts of the conveyor system has self-contained mutually independent position-controlled drives for each of the two pairs of conveyor belts. As a result, no form-locking continuous connections prone to wear are required in the drive train. The replacing of the conveyor belts is significantly simplified, as is the installation and removal of additional processing devices, for instance for blank separation or special blanking.

In accordance with another advantageous feature of the invention, the drives of the top-related and bottom-related pairs of conveyor belts are governed by motion profiles through the control units or through a central machine control unit. The motion profiles for the two pairs of belts herein can be identical or different in each case. Thus, it is possible to control conveying of the product from one cutting station to another in such a way that different transport paths are consciously selected for the top and bottom ends of the product in order to achieve the desired cutting result.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures of the drawings in detail and first, particularly, toFIG. 1Athereof, there is seen a representative example of a cutting device19for edge trimming with separate drive devices according to the prior art. A first drive motor1generates a motion of an upper knife carrier2, on which upper blades3are mounted. The direction of product flow is indicated by arrows T. A second drive motor4drives belts7,8of a conveyor system9through respective first and second continuous drive shafts5,6. Control units10,11which are provided for the two drive motors1,4can communicate with one another by a connection12for an exchange of data and/or control signals. Moreover, the connection12can also lead to a central machine control unit18.

Important elements of the drives generating the two motion sequences are shown inFIG. 1B. The first drive motor1generates a vertical anharmonic oscillating motion of the upper knife carrier2using a timing belt15, a timing belt pulley16and a transmission17. During a cutting action, the upper blades3are pressed against lower blades13. The second drive motor4drives the shafts5,6by using a mechanical transmission14, in such a way that the belts7,8of the conveyor system are moved. The arrows T again mark the direction of the product flow.

FIGS. 2 and 3illustrate a cutting device20according to the invention in which, for the sake of clarity,FIG. 3illustrates only a top-related conveyor system and omits control units and connections. The cutting device20has an upper knife carrier25which is set into vertical motion by a drive motor21. The upper knife carrier25extends through all of the cutting stations. There are three cutting stations in the present example: a station26for front edge trimming, a station27for top and bottom trimming and a further processing station28for special blankings or for blank separation. Corresponding upper blades29,30,31,32are attached to the upper knife carrier and are moved toward lower blades33shown inFIG. 4and thus carry out the edge trimming or special blanking or blank separation of a product40. The product40is conveyed by a conveyor system34through the individual cutting stations26,27,28of the device20. For this purpose, the conveyor system34has top-related35,36and bottom-related37,38pairs of conveyor belts between which the product40is clamped. The top-related pairs of conveyor belts35,36are driven by an independent drive motor23, and the bottom-related pairs of conveyor belts are driven by an independent drive motor22.

The individual independent drives21,22,23are linked to one another by way of their respective control units47,48,49through a connection50for the exchange of data and/or control signals. Moreover, they can be additionally connected to a central machine control unit51. This enables the respective drives22and23to be governed by a defined motion profile and thus to accelerate and convey the product40individually by its top or bottom sides.

FIG. 4illustrates the important components of the conveyor system34. The direction of transport of products40,40′,40″ is illustrated by arrows T. In the present exemplary embodiment, the conveyor system34extends through the three cutting stations. In the first station26, the front edge trimming is effected by the upper blade29and the lower blade33. In the second station27, the top and bottom trimming is effected by the upper blades31,30and the lower blade33. In the third station28, blank separation is effected by using the separating blade32and the lower blade33. In the second or third station, special blanking can also be carried out, in addition, by using corresponding cutting dies41. During the cutting, the product40remains stationary. After completion of the respective cutting operation the product40is conveyed to the next cutting station. The conveyance of the products is carried out by using the two pairs of conveyor belts35,36,37,38which are disposed opposite one another in pairs and clamp the product in each case at the top side and the bottom side in a force-locking manner.

The top-related35,36and bottom-related37,38pairs of conveyor belts are each driven by the respective independent drive motors22,23with respective components of drive trains42,43. Each of the two drive trains42,43is formed from the following components:timing belt pulleys60,61on motor shafts (the timing belt pulley61being concealedFIG. 4);timing belt pulleys63,64for driving shafts65,66for the upper belts35,37;timing belt pulleys67,68for driving shafts69,70for the lower belts36,38(the shaft70being concealed inFIG. 4);timing belt pulleys71,72used as deflection and tensioning devices (the timing belt pulley71being concealed inFIG. 4); andtiming belts73,74with toothing on two sides.

The product40is accelerated by the conveyor system34within the device20, conveyed in the correct position to the respective cutting station and then decelerated until stopped. This operation is repeated for further processing steps and finally for conveying the product from the device20to a conveyor system disposed downstream of the device20, to a processing device or to a delivery tray.

FIG. 5shows, by way of example, a possible motion profile of a pair of conveyor belts for an entire working cycle (0-360°) of the cutting device. InFIG. 5, the upper diagram illustrates the travel of a cam disk in degrees of rotation, the diagram in the center illustrates the first derivative as standardized velocity (ds/dPhi) and the lower diagram illustrates the second derivative as standardized acceleration (dv/dPhi), each over 0°-360° (x axis), corresponding to a machine cycle. Reference numerals100,105respectively indicate the bottom dead center of the upper knife carrier at 0° and 360°. At this point, the cutting operation is completed but the product is not yet released. Accordingly, the pair of conveyor belts is not yet in motion. At a point101the product is released and the conveying operation can commence. Accordingly, at the point101the travel of the cam disk is still zero, as is the velocity. The acceleration of the conveyor belts commences at the point101, as is shown in the lower diagram ofFIG. 5. The acceleration of the conveyor belts continues until a point102(approx. 164°). Up to there the cam disk has covered a distance of approximately 130 degrees of rotation and the conveyor belts are moving at a standardized velocity of 3.2. No further acceleration occurs until a point103, with the conveyor belts thus continuing to move at the same velocity. From the point103to a point104the positioning of the product in the next cutting station takes place or a new product is positioned in the first cutting station. Accordingly, the conveyor belts are correspondingly decelerated until stopped. From the point104to a point105the belts remain stationary. In the respective cutting station the product is clamped by using non-illustrated clamping bars, the upper knife carrier is lowered to its bottom dead center and thus the edge trimming of the product40is carried out.