DESCRIPTION:

Technical field of the invention

The invention relates to a drum for use in a cutting device for cutting leaves from flowers of plants, which drum is open at both ends and has a drum wall provided with openings, wherein during operation the leaves to be cut off protrude through the openings in the drum wall.

Background of the invention

A cutting device provided with a drum according to the preamble of claim 1 is known from US 2017/0164557 Al. The drum of this known cutting device has a wall formed by a plate provided with perforations. In use, flowers are fed into the drum through an open end and the drum is rotated along one or more knives. During rotation leaves protrude through the perforations to outside the drum and are thereby cut off by the knives.

US10,602,679B2 discloses a drum apparatus for use in a cutting device. The drum apparatus is provided with a drum, the wall of which is formed by wall elements distributed over the circumference and spaced apart from one another, which wall elements are for instance designed as rods. In this case, too, during rotation of the drum leaves of the flowers protrude through the openings present between adjacent wall elements to be cut off by the knives.

The wall of the drum is regularly damaged during use in a cutting device, for example because when flowers are introduced into the drum, hard objects unintentionally get between the flowers and during the rotation of the drum protrude through the openings and get trapped between the knives and the drum wall, thereby deforming (indenting) the drum wall.

Repairing a damaged (indented) drum is time-consuming because damaged wall elements or sometimes the entire wall has to be replaced. Summary of the invention

An object of the invention is to provide a cutting device according to the preamble of claim 1 in which the repair of damaged drums can be carried out faster and cheaper. To this end the drum according to the invention is characterized in that the drum wall is wholly or largely manufactured from memory metal. Preferably, the entire drum wall is made of memory metal. Memory metal and its characteristic properties are generally known, inter alia from MEHRPOUYA M ET AL: “An investigation on the optimum machinability of NiTi based shape memory alloy”, Database accession no. 17461332; & Materials and Manufacturing Processes Taylor & Francis UK, part 32. No. 13, pages 1497-1504, ISSN: 1042-6914, DOI: 10.1080/10426914.2017.1279290.

Memory metal objects, because of their ability to return to their original shape when heated, and because of their price, are mainly used in medicine, where they are often used for stents. Memory metal is also used as an actuator. However, it is not obvious to make construction parts of memory metal with the aim to dent them by heating when indented. This application is outside the more common applications in switches and sensors. To manufacture a drum wall from memory metal in particular is so far from known applications that this has never been thought of and is therefore not obvious.

Alloys often used as memory metal (shape memory alloy) are copper- zinc-aluminium alloys. Preferably, however, a nickel-titanium alloy (Nitinol) is used as memory metal for the drum wall, despite the fact that this is much more expensive than the more common copper-zinc-aluminium alloys. The advantage of Nitinol as a memory metal compared to other memory metals is that it is relatively strong, so that objects made from it can be thin. This is particularly favorable when used in drums of cutting devices, because preferably as many leaves as possible have to be cut off from the flowers. By using drums with thin walls, greater parts of the leaves protrude from the drum and greater parts of the leaves are cut off. In addition, nickel-titanium alloys have better mechanical properties, such as the greater degree of deformation, while still returning to the original shape.

In one embodiment, the drum wall is made of a plate and the openings being formed by perforations in the drum wall. In another embodiment, the drum wall has a number of elongate wall elements extending parallel to the longitudinal axis of the drum and being distributed over the circumference of the drum and being spaced apart, the space between the wall elements forming the openings through which the leaves to be cut off stick out during operation.

In this latter embodiment, the drum preferably has two rings spaced apart, one at each end of the drum, the elongated wall elements being attached to the rings at their ends and extending between the rings, and the drum furthermore has tensioning means for keeping the wall elements taut between the two rings, which tensioning means are connected to the two rings and exert an axial force on each of the rings, which forces are directed away from each other.

In an embodiment, the tensioning element extends in the middle of the drum and is connected to the rings near the ends via connecting constructions, one of the ends being movable relative to the respective connecting construction. By applying one centrally arranged tension element, the force exerted on the rings is distributed evenly over the rings, so that the same tension force acts on all wall elements.

In another embodiment, the cutting device has at least three tensioning elements which are distributed over the circumference of the rings and which extend between the rings and which extend between or next to the wall elements. The advantage of this is that there is nothing inside the drum that hinders the introduction of plants to be processed.

Preferably, the tensioning means furthermore have at least one adjusting element, wherein the tensioning element or each tensioning element is attached with a first end to one of the rings or to one of the connecting structures and is coupled with the other, second end via the adjusting element with the other ring or the other connection construction, whereby the adjusting element can be used to move the rings apart or towards each other.

The tensioning element is preferably provided with screw thread at the second end which co-acts with further screw thread of the adjusting element which is rotatably connected to the other connecting construction, the tensioning element and the adjusting element being moved relative to each other in longitudinal direction by rotation of the adjusting element.

In order to be able to remove the drum from a cutting device simply and quickly, an embodiment of the cutting device is characterized in that at least one of the rings has a toothing in the ring on the outside, which toothing has a number of teeth arranged one behind the other in the circumferential direction of the ring, wherein the space between two teeth arranged one behind the other is limited in axial direction of the drum by delimiting parts of the ring present there. The cutting device in which the drum is used should have at least one gear meshing with the teeth in the ring, the meshing teeth of the gear being axially confined between the delimiting portions of the inter-tooth space of the toothing in which the meshing teeth are located. The limiting parts of the ring, which are pressed against the meshing teeth of the gear wheel when the drum moves axially, prevent the drum from shifting in the axial direction. Therefore, the drum need not be enclosed in bearings in the cutting device according to the invention.

Preferably, a circumferential groove is arranged in the ring on the outside of the other ring, the space in the groove being limited in axial direction of the drum by boundary walls of the ring present there. The cutting device in which the drum is used has at least one roller which is partly present in the groove and is confined in axial direction between the boundary walls of the groove. By using this groove it is not even necessary for the teeth to counteract axial displacement of the drum. As a result, it is not necessary to arrange the teeth in one ring and, for example, the teeth can also be present on the ring instead of in it. The teeth could even be omitted completely and the drive could take place by a belt or friction wheels.

The wall elements are preferably formed by wires (cables) or rods with a diameter between 0.5 and 2 mm so that the leaves of the tops of the cannabis plants can stick out more.

The invention also relates to a cutting device for cutting leaves from flowers of plants, comprising the drum described above, first rotation means for rotating the drum about the longitudinal axis, and at least one elongate knife provided with a cutting edge, which knife being next to the drum.

Instead of being integrated in the drum, the tensioning means for keeping the wall elements taut between the two rings can also be present outside the drum in the cutting device and exert an axial force on each of the rings, which forces being directed away from each other. Brief description of the drawings

The invention will be explained in more detail below on the basis of exemplary embodiments of the cutting device according to the invention shown in the drawings. Hereby:

Figure 1 shows a first embodiment of the cutting device, viewed in side view on the rotation means for the knives;

Figure 2 shows the cutting device shown in figure 1, viewed in side view on the rotating means for the drum;

Figure 3 shows the cutting device shown in figure 1 in longitudinal section according to line III- III in figure 1 ;

Figure 4 shows the drum of the cutting device shown in figure 1 with the knives in perspective;

Figure 5 shows the drum shown in figure 4 separately in perspective;

Figure 6 shows a perspective view of a drum of a second embodiment of the cutting device according to the invention;

Figure 7 shows the drum shown in figure 6 in longitudinal section; and

Figure 8 shows a drum of a third embodiment of the cutting device according to the invention in longitudinal section.

Detailed description of the drawings

Figures 1-3 show a first embodiment of the cutting device according to the invention for cutting leaves between the flowers of the tops of cannabis plants. The cutting device 1 has a box 3 in which a frame 5 is present. In the frame 5 there is a rotatable drum 7 into which the buds of cannabis plants to be treated must be placed. The drum 7 has two spaced apart rings 9 and 11, one at each end of the drum 7. These rings are formed by short lengths of tubing. A drum wall is present between the rings 9 and 11, which is formed by a number of elongate wall elements 13, which are attached to the rings 9 and 11 at their ends and extend parallel to the longitudinal axis 15 of the drum 7. The wall elements 13 are distributed over the circumference of the drum 7 and are spaced apart. During operation, the leaves to be cut protrude through the openings 17 present between the wall elements. The wall elements 13 are formed by rods of memory metal with a round cross-section with a diameter of 1 or 1.5 mm. Nitinol is preferably used as memory metal. In figures 4 and 5 the drum 7 is shown separately and the wall elements 13 are clearly visible.

The cutting device 1 furthermore has three knife reels 20, each with three spiral-shaped knives 21, see also figure 4, in which one of the knife reels is clearly visible. The knives are provided with cutting edges 23 which are present on the periphery of the knife reels. The knife reels 20 are present next to the drum 7 and are rotatable about rotation axes 27, the cutting edges 23 of the knives 21 being spaced from the rotation axes 27. The rotation axes 27 are parallel to the longitudinal axis 15 of the drum 7 so that the knives 21 rotate close to the outside of the drum 7 during operation.

The cutting device 1 furthermore has first rotation means 19 for rotating the drum 7 about the longitudinal axis 15, see in particular figure 2. These first rotation means 19 have an electric motor 51 which via a belt 53 drives a gear wheel 55 which is in engagement with a toothing 57 present in one of the rings 11. Furthermore, the cutting device 1 has second rotation means 25 for rotating the knife reels 20, see in particular figure 1. These second rotation means 25 also have an electric motor 61 which drives pulleys 65 mounted on the rotation shafts 27 of the reels 20 via a belt 63.

The ring 9 of drum 7 is loose on rollers (not visible in the figures) and the ring 11 of drum 7 is loose on two gears 55 and 59, see figure 2. The drum 7 can thus in upward direction be taken out of the cutting device by opening a cover on top of the frame. In order to be able to easily remove the drum 7 from the cutting device, the drum is preferably of sturdy design. The strength of the drum 7 is obtained by tensioning means 29 which keep the wall elements 13 taut between the two rings 9 and 11. The tensioning means 29 have a tensioning element 31 formed by a threaded rod which is connected to the two rings 9 and 11 via connecting constructions 33 and 35, see figure 1. These connecting constructions are formed by three arms which are attached with one end to the inside of the rings and which are attached to a sleeve with the other ends, see also figures 4 and 5. One of the sleeves is attached to an end 31a of tensioning element 31 and the other sleeve is provided with internal screw thread into which an adjusting element 37 provided with external screw thread can be rotated, see figure 1. This adjusting element (bush) 37 is provided with an opening 39 with internal screw thread into which the other end 31b of the tensioning element 31 is present. By turning the adjusting element 37, the rings 9 and 11 are moved away from each other, so that the wall elements 13 are put under tension and the drum 7 is given stability. The cutting device 1 furthermore has adjusting means 41 with which the distance between the rotation shafts 27 of the knife reels 20 and the longitudinal axis 15 of the drum 7 can be adjusted, see figures 1 and 2. Each knife reel 20 has three knives 21 which are attached with their ends to discs 43 and which extend helically between the discs, see figures 3 and 4. The discs 43 are mounted on the rotation shafts 27, which with their ends are mounted in slides 45. The pulleys 65 are mounted on one of the ends of the rotation shafts 27. The carriages 45 are displaceable in a direction radial to the longitudinal axis 15 of the drum 7. The position of the slides 45 and thus the distance from the knives 21 to the wall parts 13 of the drum 7 can be adjusted by adjusting screws 47.

In figures 6 and 7 a drum 107 of a second embodiment of the cutting device according to the invention is shown in perspective and in longitudinal section, respectively. Between the rings 109 and 111 there are three tensioning elements 131, which are formed by rods and which are fixed with a first end 131a to one of the rings 109 and which are sticks in a hole 115 in the other ring 111 with the other, second end 131b and can be slid into it. Over part of its length, this hole is provided with internal screw thread, in which an adjusting element 137 provided with external screw thread can be rotated. The wall elements 113 of the drum wall are again designed as memory metal rods and are attached to the rings 109 and 111 at both ends. Here, too, openings 117 are present between the wall elements 113 for allowing leaves to protrude outwards during operation. Between the rings, the wall elements 113 are mutually connected at a number of places by annular bands 112. By turning the adjusting elements 137 further into the holes 115, the rings 109 and 111 are pushed apart, so that the tension in the wall elements 113 increases.

A toothing 133 is arranged in the ring on the outside of the ring 109. This toothing has a number of teeth arranged one behind the other in the circumferential direction of the ring. The space between two teeth located one behind the other is limited in the axial direction of the drum by limiting parts of the ring 109 present there. The rotation means have at least one gear meshing with this gear 133. The meshing teeth of the gear are confined in axial direction between the delimiting parts of the space between the teeth of the toothing in which the meshing teeth are located.

On the outside of the ring 111, a circumferential groove 139 is provided in the ring. The space in the groove 139 is limited in the axial direction of the drum 111 by boundary walls of the ring present there. The shearing device has three rollers, each of which is partly present in the groove 139 and is axially confined between the boundary walls of the groove.

Figure 8 shows a drum 207 of a third embodiment of the cutting device according to the invention in longitudinal section. The wall 213 of this drum is formed from a circular cylindrical tube provided with perforations 217. No tensioning elements are present here between the rings 209 and 211. The wall 213 of this drum 207 is manufactured from Nitinol, so that it is sufficiently rigid in itself and no tensioning means are required.

Here, too, a toothing 233 is present in the ring 209 and a circumferential groove 239 is present in the ring 211 for rotating and retaining the drum 207 in axial direction.

Although the present invention is elucidated above on the basis of the given drawings, it should be noted that this invention is not limited whatsoever to the embodiments shown in the drawings. The invention also extends to all embodiments deviating from the embodiments shown in the drawings within the scope of the invention defined by the appended claims.