TECHNICAL FIELD
[0001] The invention relates generally to a device for de-husking finger millet and more specifically to a continuous device capable of de-husking large amounts of ragi.
BACKGROUND
[0002] Ragi is main food grain for many people around the world, especially in the tropical countries, and even in high altitude regions. For example, ragi constitutes over 25% of the food grains grown in India, and is the staple food grain for those living in rural areas. Processing of Ragi involves two processes namely ‘threshing’ and ‘de-husking’. The dry stalks are threshed by passing heavy rollers over them. The de-husking of ragi is currently done manually and is highly labour intensive, which takes about 4 hours to de-husk 5 Kg of Ragi. Typical steps involved in post harvesting of ragi include: matured ragi plants are cut and dried in the farm land itself for period of a week depending on the weather to reduce moisture content; the dried ear heads of Ragi plant are collected and stored for around 15 days; then heavy objects are used to roll over or beat the ear heads rollers are run over them to separate grain from straw, referred to as ‘threshing’; de-husk is achieved manually by rubbing in hands which is very laborious and time consuming; then the ragi and husk are separated by allowing free fall of ragi and husk from a height of around 10 feet, wherein due to the blowing of wind, husk gets separated and flies along with it.
[0003] In some instances, rice de-husking machines are being used for ragi de-husking, which requires at least 10 laborers. It runs on roller concept and the efficiency is found to be less than 60%.
[0004] De-husking for a variety of other crops and grains are known and equipment designed for that specific purpose are available today. US2358961 describes a machine for husking corn by slitting knife for the separation of corn with roller provision for feeding corn ears one after another in the direction of their length into the machine. US5167580 provides a device for husking corns by removing the husks and silks with minimum damage to the kernels. The device consists of two rollers having adjustable rotation mechanism and selected direction and in sequence. This device also has provision for the cutting the butt end off the ear and positioning the ear closely between the spaced rotating rollers in opposite directions to remove the husks.
[0005] US5678477 includes a paddy husking machine, which consists of supplier of the husking material in layers, two rollers with adjustable clearance and rotating in opposite directions with differential speeds and with minimum damage to the husking material.
[0006] US2010/0018177A1 describes a combined apparatus for threshing of corn kernels from cobs and de-husking of cobs, cleaning other crops residues or materials from the kernels, collection of cleaned material. The de-husking machine could include modified type of husking bed with provision for flow of grain, cobs and residues from threshing machine as well as for the disposal of material to the field separately or with other residues.
[0007] Jarimopas et al (Bundit Jarimopas, Suttiporn Niamhom, Anupun Terdwongworakul; Biosystems Engineering 2009, Vol. 102, pp. 83-89) have described a husking machine for dry betel nut (Areca Catechu Linn). The design concept used is to tear-off the husk of the dry betel nut by exerting differing dynamic friction forces on opposite sides of the nut via normal pressure. The prototype fabricated consisted of a hopper into which dry betel nuts could be fed, a husking mechanism as well as a power drive. The husking mechanism consisted of two identical husking wheels mounted in series and provided with a rubber tyre and a concave sieve. The machine has the provision for the nut to pass through the first wheel, while the combined compression and friction force crushes the nut husk and loosens the nut. Then both the husk and nut could be separated by repeating the operation with a second tyre.
[0008] Despite the advances in de-husking of such a wide variety of crops and grains, and though ragi is a very important crop used so widely as food and other applications in a wide geographic regions, there is no readily available solution for any de-husking of husked ragi.
BRIEF DESCRIPTION
[0009] In one aspect, the invention provides a device for de-husking ragi that comprises a hopper to enable feeding husked ragi; a conveyor belt attached to a motor to transport the husked ragi; a spring loaded sheet at least partially in contact with the conveyor belt; a guiding sheet to guide the de-husked ragi; and a blower to blow the separated out husk.
[0010] In another aspect, the invention provides a ragi processing unit that comprises a ragi threshing unit and the device for de-husking ragi of the invention.
DRAWINGS
[0011] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
[0012] FIG. 1 is a schematic of the device for de-husking ragi.
DETAILED DESCRIPTION
[0013] As used herein and in the claims, the singular forms "a," "an," and "the" include the plural reference unless the context clearly indicates otherwise.
[0014] As used herein, the term "Ragi" is a cereal from the plant Eleusine Coracana. Ragi is also known as Finger Millet, or by a variety of other names in different languages, such as African Millet in some parts of the world, Kezhvaragu in Tamil, and so on.
[0015] As used herein, the term "Husk" means the outer covering of ragi grain. It may also be sometimes referred to as hull. The process of removal of the husks to reveal the grain inside is called "De-Husking," also referred to as simply husking, or de-hulling, or hulling, or chaffing.
[0016] As noted herein, in one aspect the invention provides a device for de-husking ragi. Fig. 1 shows a schematic of the device, which is generally represented by the numeral 10. The device comprises a hopper 12 through which husked ragi is fed. The hopper may be a gravity-based hopper where the feeding rate is dependent on gravity. Alternately, the hopper may comprise a motorized feeding chute through which the rate of feed is controlled. The hopper may further comprise hatches to control feed. The size of the opening and the other dimensions associated with the hopper will depend on various factors, such as, but not limited to, size of husked ragi, number of husked ragi being fed at any given time period, and the like, and may be arrived at without undue experimentation by one skilled in the art. Other variations will become obvious to one of ordinary skill in the art.
[0017] The device 10 then comprises a conveyor belt 14 controlled by a motor 16. The conveyor belt is an endless belt known in the art. The speed at which the conveyor belt is operated is decided based on the feed rate of the husked ragi, the time taken for dehusking ragi, and the like. The motor may be any mechanical motor that is hand-operated or a powered motor that uses an appropriate fuel.
[0018] The device of the invention 10 comprises a spring loaded sheet 18 that is at least partially in contact with the conveyor belt. The device is configured in such a way that when the conveyor belt 16 transports the husked ragi along its length, the husked ragi comes into contact with the spring loaded sheet. The sheet raises high enough to allow the husked ragi to pass underneath it, however due to the spring action, some amount of pressure is applied onto the husked ragi. This pressure is sufficient to cause the husk to crack open to release the grain from within it. The thickness of the spring loaded sheet varies, and in one embodiment, is about 2 millimeters. However, other thicknesses useful in the invention may be arrived at by one skilled in the art without undue experimentation. In some embodiments, the spring loaded sheet 18 is completely in contact with the conveyor belt 16 such that the conveyor belt 16 rubs along one side of the spring loaded sheet during operation. In Fig. 1, one portion of the spring loaded sheet is shown to be raised to accommodate the presence of the hopper 12, after which it is shown to taper down uniformly to come into contact with the conveyor belt 16.
[0019] The spring loaded sheet is advantageously made of a suitable metal, such as steel, iron, aluminium, titanium, alloys like brass, bronze, and the like. Other useful materials for making the spring loaded sheet include wood, cardboard, plastic such as polypropylene, and the like, and combinations thereof.
[0020] The spring loading used in the invention is advantageously a compression loading mechanism, wherein in the normal state the spring is fully stretched, whereas during operation when it comes into contact with the husked ragi, it compresses to provide the pressure necessary for de-husking. In some embodiments, the pressure exerted by the spring loaded sheet is at least about 1.0 N/mm2, while in another embodiment, the pressure is at least about 2.5 N/mm2.
[0021] The dehusked ragi along with the empty husks are transported by the conveyor belt and at the end of the conveyor, it is allowed to fall under the effect of gravity. A guiding sheet 20 is provided at a distance from the conveyor belt. This allows for the empty husks and the ragi grain to be directed towards a particular location, such as a receptacle (not shown in Fig.).
[0022] The device 10 further comprises a blower 22 that blows air in a direction whose axis is approximately perpendicular to the axis of the plane of the falling grains and husks. A typical blower is a fan of suitable blade size and width with sufficient power to drive the air with a required velocity. In the configuration shown in Fig. 1, the fan is shown to be placed below the conveyor belt. The husks are extremely light weight, and they tend to float in the direction of any slight air movement. The grains being heavier require greater airspeed to make them move in the direction of the air flow. Thus, the grains may be separated from the husks by blowing air with a certain airspeed that blows the husks away while not affecting the grains path. The required airspeed may be easily arrived at by one of ordinary skill in the art. To achieve the separation, the direction of airflow is not particularly important, however, for ease of operation and to facilitate subsequent clean-up operations, the direction of airflow may be towards a particular area such as a waste area.
[0023] The device may further comprise receptacle to collect the grains as they fall. The receptacle may be o a suitable shape and size to receive the requisite amount of grain in a given production plant. Alternately, the receptacle may be a replaceable one wherein as soon as the first receptacle is filled, it is replaced with a second receptacle.
[0024] The device of the invention also comprises a frame 24 onto which all the various components are mounted suitably, as shown in Fig. 1.
[0025] The design of the device of the invention include, among other things, ease of fabrication, light weight, portability, cost effectiveness, affordability, ease of operation, fairly low cost of operation, labour non-intensive, time saving, simplicity of operation, possibility of operating manually in the absence of electricity. Further, the device of the invention may be configured to include a solar unit for powering any electrical parts. This device may also be attached to a ragi threshing unit to allow for a single Ragi processing unit. A drying unit may be included to process wet Ragi husk can be used. Other possibilities towards automation using the electronic components such as sensors etc. are also contemplated to be within the scope of the invention.
[0026] The device of the invention was used to de-husk 5 kg of ragi with husk. The husked ragi was manually poured into the hopper, and the de-husked ragi was collected in a tray at output section. Quality of ragi was good, it took around 15 minutes to complete operation including initial optimization. Manual operation in the machine took around 1 hour.
[0027] While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
We Claim:
1. A device for de-husking ragi, wherein the apparatus comprises:
a hopper to enable feeding husked ragi;
a conveyor belt attached to a motor to transport the husked ragi;
a spring loaded sheet at least partially in contact with the conveyor belt;
a guiding sheet to guide the de-husked ragi; and
a blower to blow the separated out husk.
2. The device of claim 1 wherein the spring loaded sheet is completely in contact with the conveyor belt.
3. The device of claim 1 wherein the spring loaded sheet has a thickness of about 2 millimeters.
4. The device of claim 1 further comprising a frame.
5. The device of claim 1 further comprising a receptacle.
6. The device of claim 1 further comprising a drying unit.
7. A ragi processing unit comprising:
a ragi threshing unit; and
a device for de-husking ragi,
wherein the device for de-husking ragi comprises a hopper to enable feeding husked ragi; a conveyor belt attached to a motor to transport the husked ragi; a spring loaded sheet at least partially in contact with the conveyor belt; a guiding sheet to guide the de-husked ragi; and a blower to blow the separated out husk.