A knife or a plurality of knives is mounted on the circumferential surface of a rotary cutter drum of a cutting machine, as presented in previous applications to ITM Poland Lld. During treatment of organic plant materials, particularly tobacco materials, the materials are wetted so that moisture content is appropriate for the organic plant material type and the type of the process/treatment being carried out. Additionally, the organic plant materials, particularly tobacco materials, may be subjected to liquids of much higher density and viscosity than those of water, remaining partially on external surfaces of the processed particles.

During the cutting/comminuting process of wetted organic plant materials, particularly tobacco materials, the compressing force is applied, keeping the continuously fed material within the cutting zone, as well as the cutting/comminuting forces are applied.

Mainly under these forces some of viscous liquids are squeezed out from a portion of the plant material, the liquids, when mixed with particles of the organic plant material dust, particularly tobacco, tending do settle in the nearest neighbourhood of the cutting/comminuting knives. The settling process of the combination of the above mentioned liquids and the dust as tiny particles causes building up a layer which hardens when drying and adversely affects the subsequent cutting/comminuting process.

Up to now the cleaning operation of surfaces surrounding the revolving knives in the cutter drum for cutting/comminuting organic plant materials, particularly tobacco materials, was performed manually utilising various manual scrapers. In so far produced machines the removal of the buildup was carried out only after stopping the machine, this adversely affecting the quality of the cut/comminuted organic plant material.

According to the invention, the scraper for cleaning surfaces around revolving knives in a cutter drum for cutting/comminuting organic plant materials, particularly tobacco materials, is characterised in that the scraper is mounted in a holder of the rotary shaft of the scraper coupled with the cutter drum shaft, the shaft of the scraper and the cutter drum having a common drive.

Preferably, ratios of the thickness T of the material of the scraper to its working length L satisfy the relationship : T 2 e, where e is the base of the natural logarithm.

Preferably, the dependency: L2 5@ is satisfied between the diameter D of the cutter drum of the cutting machine and the working length L of the scraper.

The cutter drum shaft is coupled with the rotary shaft of the scraper via an assembly of tensioners with a driving tension member, which, preferably, has a form of a toothed belt.

The scraper is located on the side of the cutter drum opposite relative to the cutting/comminution zone.

Preferably, the holder is mounted on the rotary-shaft at two points.

Preferably, the holder is mounted on the rotary-shaft at three points.

The rotational speed n of the shaft of the scraper relative to the rotational speed of the cutter drum of the cutting machine is selected according to the dependency: n=Kn/No, where Kn denotes the number of the cutting/comminuting knives on the circumference of the drum and No is an arbitrary odd natural number. Preferably, the above mentioned dependency is 16: 3, 16 : 5 or 16: 7 so that the scraper removes the buildup from every successive odd knife, starting from the beginning, for example every 3d, every 5th etc.

The rotational speed of the shaft is synchronised with the rotational speed of the cutter drum with the ratio for which the revolving cleaning edge of the scraper contacts every odd in succession blade of the cutting/comminuting knife.

The revolving scraper according to the invention allows for continuous removal of the forming buildup during operation of the cutting/comminuting machine for organic plant materials, particularly tobacco materials.

Employing the inventive scraper allows for continuous, simple, convenient and reliable removal of the buildup from the blade zone of the cutting/comminuting knife.

The working tip of the scraper dives into the contour of the trajectory defined by the knives of the drum so that the amount of the removed buildup is possibly maximal without any collision of the two rotating elements.

The structure of the scraper allows for advantageous vibrations of the scraper material.

The invention will now be described by way of example only with reference to the accompanying drawing, in which:

Fig. 1 is a side view of the scraper according to the present invention, with the shaft being coupled with the cutter drum ; Fig. 2 shows the device from Figure 1 in a perspective view; Fig. 3 shows the configuration of the scraper relative to the cleaned knife during the cleaning operation; Fig. 4 shows geometrical parameters of the scraper according to the invention ; and Fig. 5 shows deflection of the scraper according to the invention.

Figures 1 and 2 show the rotary shaft 4 equipped with the scraper 3, the rotational speed of which is synchronised with the rotational speed of the cutter drum 1 with the ratio for which the revolving cleaning edge of the scraper 3 contacts every odd in succession blade of the cutting/comminuting knife 5. The rotational motion of the scraper 3 is transferred from the shaft of the revolving cutter drum 1 via the driving tension member 2 in a form of a belt or a chain, preferable a toothed belt/chain, via an assembly of tensioners 6,7 to the shaft 4 of the scraper 3. The rotational speed n of the shaft 4 of the scraper 3 in relation to the rotational speed of the cutter drum 1 of the cutting machine is selected according to the dependency : n =-, where Kn denotes the number of the ?) cutting/comminuting knives 5 on the circumference of the cutter drum 1 and No is an arbitrary odd natural number. Preferably, in the above mentioned dependency n is 16: 3, 16: 5 or 16: 7 so that the scraper 3 removes the buildup from every successive odd knife 5, starting from the beginning, for example every 3çd, every 5 etc. Thus after several, for example after 3,5 etc, revolutions, all the knives 5 and/or their surroundings will be subjected to the operation of the scraper 3.

As shown in Fig. 3, the rotary scraper 3 is characteristically configured relative to the cutter drum 1 and its dimensions are beneficially selected so that the rotary tip of the scraper 3 dives into the contour of the trajectory defined by the knives 5 of the cutter drum 1 of the cutting machine so that the amount of the removed buildup is maximal without any collision of the two rotating elements. Preferably, main parameters determining the optimal depth of the penetration into the area external relative to the upper surface of the knife 5 and the external pressing plate 8, are ratios of the working length L of the scraper 3 to the diameter D of the cutter drum 1.

Preferably, the scraper 3 is placed on the side of the cutter drum 1 opposite relative to the cutting/comminution zone.

The geometrical parameters of the scraper 3 arc presented in Fig. 4 and they show preferable proportions of the thickness T of the material of the scraper 3 to its working length L.

Preferably, the dimensions satisfy the relationship : T 2 e, where e is the base of the natural logarithm. The proportion is connected with the functional feature of the scraper 3, the feature being advantageous vibrations of the material of the scraper 3 during its operation. The thickness T of the scraper 3 depends on the material the scraper is made from and on the strength parameters of the material, including rigidity against bending forces and stresses generated due to the operation of the scraper 3 (cyclical interaction with the buildup and its removal) and so occurring deflections d, as shown in Fig. 5.

Additionally, in order to obtain the above mentioned results it is preferable to preserve the following dependency: L/D between the diameter D of the cutter drum 1 of the cutting machine and the working length L of the scraper 3.

The objective of the manner the scraper 3 is mounted, the objective of the type of the material it is made from as well as the objective of the selection of its dimensional proportions is the mechanical removal (scraping) of the buildup which is a mixing of liquids from the cut/comminuted tobacco material with possible admixture of tobacco particles. One way of achieving this objective is mounting the scraper 3 in the holder 9 of the rotary shaft 4 such that the vibrations of the material of the scraper 3 are obtained and maintained in the preferable range. In the presented solution the scraper 3 is mounted at two points, preferably at three points.