AU2231800A - A decortication machine and method of decortication - Google Patents

Description

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1

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION STANDARD PATENT 6 a a.

a. a a a a a.

a "A Decortication Machine and Method of Decortication" The following statement is a full description of this invention, including the best method of performing it known to me: A DECORTICATION MACHINE AND METHOD OF DECORTICATION Field of the Invention The invention relates to a method and machine for the processing of fibrous plant stalks.

More particularly the invention relates to the processing of hemp.

Background of the Invention .:o.0i S Whilst the following discussion concerns processing of hemp, it is to be understood that the same principles may apply to processing of other fibrous plant materials.

S Hemp is well known to be strong and resilient. These characteristics mean that hemp is particular suited to be incorporated into clothing, paper, rope and plaster based building **products.

Cultivation of hemp has previously been severely restricted by government regulation in an attempt to control the production of the well known drug cannabis. Recently, governments •have foreshadowed a lifting of the restriction upon the cultivation of hemp and it is expected that such cultivation will become an important crop for farmers.

The hemp plant is stalk based and the important source of fibrous material is found in the outer layer of the stalk. The stalk also includes a core which is also known as a hurd.

The common approach to recovery of the fibrous material from the stalk has been to attempt to strip the outer layer from the core. This process is commonly known as decortication.

The most basic form of decortication is scutching which entails beating the stalk to loosen the core from the outer fibrous material. The fibrous material is then separated from the core by a mechanised stripping step. This method is labour intensive, time consuming and is not suited to processing of large crops of this stalk.

Another approach is disclosed in patent application PCT/AU97/00329. This application deals principally with a decortication machine which processes green stalks of hemp by rupturing the bonds between the fibre and the hurd, splitting the stalk longitudinally, followed by decortication.

In the arrangement disclosed in this patent application, the rupture of the fibrous outer layer from the core is achieved by distortion. The stalk is passed through a serpentine path defined by a number of offset wheels. In this way the stalk is caused to bend in a number of different directions. As the core and the outer fibrous layer have different radii of S 15 curvature, the core and outer layer are forced to move independently of each other which causes the bonds between them to be weakened or broken.

The next step is splitting of the stalk longitudinally. This is achieved by a knife or saw which splits the stalk into two strips which are then each decorticated. This last step involves passing the strips about rolls which have teeth to strip or chip the core from the outer fibrous layer.

This type of process involves the use of complex mechanical arrangements which are not readily transportable and will require significant tuning to ensure that they can achieve large throughput capacities. Further, the more complex the mechanical arrangement the more expensive the machine and its maintenance.

Object of the Invention It is an object of the present invention to provide a decortication method and machine which is easily transportable and simple to manufacture and maintain.

4 Summary of the Invention According to one form of the invention, there is provided a decortication machine for a stalk having a core and a surrounding fibrous layer, the machine comprising: a substantially linear decortication path; a guide located on the path to receive the stalk and to guide the stalk in a predetermined direction; a splitter located on the path downstream of the guide to partially split the stalk; a spreader located on the path downstream of the splitter to open the stalk along the split and flatten the stalk so that the fibrous layer is beneath the core; and a decorticator located on the path downstream of the spreader to separate the core and the fibrous layer.

According to another form of the invention, there is provided a method of decorticating for a stalk having a core and a surrounding fibrous layer, the method including the steps of: feeding the stalk to a substantially linear decortication path; guiding the stalk in a predetermined direction; partially splitting the stalk; spreading the stalk along the split to flatten the stalk so that the fibrous layer is beneath the core; and S• decorticating the flattened stalk to separate the core and the fibrous layer.

ooooo Preferably the decortication path is a substantially horizontal planar surface.

Preferably, the guide is a roller mounted transversely of the path for rotational movement in the longitudinal direction of that path. The roller may include a pair of convergent surfaces which together define an opening through which the stalk passes. These rollers may be spring mounted to the path to allow them to adjust the opening to permit the root end of the stalk (usually about 16mm) to pass as well as the small end of the stalk (usually about 3mm). Some distortion of the stalk may also occur as it traverses the opening.

Preferably, the splitter is a cutter wheel mounted transversely of the path for rotational movement in the longitudinal direction of the path. The cutter wheel is spaced from the path a distance which is substantially the thickness of the fibrous layer. As such the stalk is not completely cut into two but rather severed down to the approximate depth of the fibrous layer to permit subsequent spreading and flattening of the stalk.

Preferably, the spreader defines a continuous slot through which the split stalk is to pass. It may have a generally V-shaped transverse cross section. The angle subtended by the V-shaped slot is small adjacent the point at which the stalk enters the slot. The angle subtended by the V-shaped slot increases with the longitudinal length of the spreader means so that the stalk is substantially flat as it issues from the slot. Typically the elements defining the slot may be spring mounted and as such can be set to a predetermined width "1 (eg 4mm) but still cope with variations in the size of the stalk.

Preferably, the decorticator is a wheel having radial teeth extending from it. The wheel defines a space with the path such that as the flattened stalk passes through it, substantially the entire core is initially indented. A second similar wheel may be provided downstream of the first wheel but offset from the first wheel so that the flattened and indented stalk issuing from the first wheel is bent downward and fed into the gap defined between the second wheel and the path. The second wheel strips from the fibrous layer the core indented by the first wheel.

Description of the Drawings The invention will now be further explained and illustrated by reference to the accompanying drawings in which: Figure 1 is a plan view of a decortication machine according to one form of the invention; Figure 2 is a side view of the decortication machine of Figure 1; Figure 3 is a cut away perspective view of the decortication machine of Figure 1; Figure 4 is a cross sectional view along A-A of the decortication machine of Figure 1.

In the drawings, the decortication machine 10 is shown from various aspects and includes a linear decortication path 11 upon which various elements are located.

In the sense shown in Figures 1 and 2, the stalk is fed to the machine 10 from the right and moves towards the left. Initially, the stalk encounters a guiding roller 12. This guiding roller 12 has two barrel sections 13 and intermediate tapered sections 14. The two intermediate sections 14 define an opening 15 with the path 11 through which the stalk passes. That opening 15 may be varied in size to cope with varying sizes of stalk and portions of the stalk by spring mountings. Typically, the root end of the stalk is about 16mm in diameter whilst the small end is about 3mm diameter. The guiding roller 12 aligns or centres the stalk so that it issues in a predetermined direction.

S Downstream of the guiding roller 12 is a further guide 16 made up of two guide posts 17.

These two posts 17 define an opening of about the width of the stalk and as such guide the stalk to the splitter 18 situated downstream.

Splitter 18 is a cutter wheel 19 mounted on and free to turn about an axle 20. Axle 20 is mounted in journal 21. The cutter wheel 19 defines an opening 22 with path 11. That opening is of a height equal to or greater than the thickness of the fibrous layer. As such, as the cutter wheel 19 engages the compressed stalk, the stalk is slit longitudinally down towards the fibrous layer. The lower fibrous layer is maintained substantially uncut.

Longitudinally aligned with the splitter 18 is spreader 23. The shape and components of spreader 23 are more clearly shown in Figure 3, in which a part of the spreader has been removed for illustrative purposes only, and in Figure 4.

Spreader 23 has a boat hull shape 24 which is interposed between two corresponding side bodies 25 and 26. As the split stalk encounters the nose 27, it is spread or flattened as it traverses the diverging V-shaped slot 28 defined between the boat hull shape 24 and side 7 bodies 25 and 26. Side body 26 has been removed from Figure 3 to better illustrate the boat hull shaped portion 24 of the spreader 23. These components are spring mounted and therefore whilst the thickness of the slot 28 is usually preset at 4mm, they can move to cope with variations in each stalk and between stalks. The slope of V-shaped slot 28 decreases in a downstream direction. Accordingly, the stalk issuing from the rear of the spreader 23 has been flattened so the fibrous layer is underneath the opened core.

This flattened stalk is then fed between a flattening roller 29 to further flatten and reduce the resilience still present in the stalk and to prepare the stalk in the correct form for processing by decortication devices 30 and 31.

The decortication devices 30 and 31 each have radially positioned teeth 32 and, as viewed in Figure 2, rotate in a clockwise direction. The teeth 32 in decortication device 30 indent the core from the stalk. Decortication device 31 is offset longitudinally from the path 11 I s15 and defines a gap 33. The first indented stalk issuing from the decortication device passes through the gap 33 and is then subjected to stripping. This leaves essentially only the fibrous layer after this process which is then able to be further processed by conventional means to produce hemp.

It will be appreciated that the machine according to the invention is small and easy to transport. It is relatively simple to manufacture and therefore relatively inexpensive.

Accordingly, it is possible to produce hemp on a large scale more economically than hitherto known.

Modifications and improvements to the invention will be readily apparent to those skilled in the art. Such modifications and improvements are intended to be within the scope of this invention.

It will be also understood that where the word "comprise", and variations such as "comprises" and "comprising", are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features.

Claims (16)

1. A decortication machine for a stalk having a core and a surrounding fibrous layer, the machine comprising: a substantially linear decortication path; a guide located on the path to receive the stalk and to guide the stalk in a predetermined direction; a splitter located on the path downstream of the guide to partially split the stalk; a spreader located on the path downstream of the splitter to open the stalk along the **split and flatten the stalk so that the fibrous layer is beneath the core; and a decorticator located on the path downstream of the spreader to separate the core and the fibrous layer.

2. A machine according to claim 1 wherein the decortication path is a substantially S 15 horizontal planar surface.

3. A machine according to claim 1 or 2 wherein the guide is a roller mounted transversely of the path for rotational movement in the longitudinal direction of that path.

4. A machine according to claim 3 wherein the roller includes a pair of convergent surfaces which together define an opening through which the stalk passes.

5. A machine according to claim 3 or 4 wherein the roller is spring mounted to the path to allow it to adjust a gap therebetween to permit the root end of the stalk to pass as well as the small end of the stalk.

6. A machine according to any one of the previous claims wherein the splitter is a cutter wheel mounted transversely of the path for rotational movement in the longitudinal direction of the path.

7. A machine according to claim 6 wherein the cutter wheel is spaced from the path a distance which is substantially the thickness of the fibrous layer.

8. A machine according to any one of the previous claims wherein the spreader defines a continuous slot through which the split stalk is to pass.

9. A machine according to claim 8 wherein the continuous slot is a generally V-shaped transverse cross section.

A machine according to claim 9 wherein the angle subtended by the V-shaped slot is small adjacent the point at which the stalk enters the slot.

11. A machine according to claim 9 wherein the angle subtended by the V-shaped slot increases with the longitudinal length of the spreader so that the stalk is substantially flat as it issues from the slot.

12. A machine according to any one of claims 9 to 1 1 wherein the generally V-shaped slot is defined by spring loaded elements.

13. A machine according to any one of the previous claims wherein the decorticator comprises a wheel having radial teeth extending from it.

14. A machine according to claim 13 wherein the wheel defines a space with the path such that as the flattened stalk passes through it, substantially the entire core is initially indented.

15. A machine according to claim 13 or 14 further including a second similar wheel .i downstream of the first wheel but offset from the space between the path and the first S 15 wheel so that the flattened and indented stalk issuing from the first wheel is bent downward and fed into a gap defined between the second wheel and the path.

16. A method of decorticating for a stalk having a core and a surrounding fibrous layer, the method including the steps of: feeding the stalk to a substantially linear decortication path; oo o guiding the stalk in a predetermined direction; partially splitting the stalk; spreading the stalk along the split to flatten the stalk so that the fibrous layer is beneath the core; and decorticating the flattened stalk to separate the core and the fibrous layer. Dated this 15th day of March 2000 John Holroyd and Narelle Pattison by their patent attorney Norman Morcom