Treating Cereal Grains And Seeds

Abstract

Seeds and grains are dehulled in an apparatus comprising a drum rotating in a casing. The seeds are first treated in a radial gap between an end face of the drum and the casing and then between a peripheral face of the drum and a surrounding part of the casing.

Description

The present invention relates to the dehulling and cleaning of cereal grains and other seeds so as to be ready for milling. More particularly the invention relates to the dehulling and cleaning of grains such as barley to remove spikes, woody fiber layers, and foreign bodies, in which all harmful bacteria and insects are removed. In accordance with the invention the germ may either be removed or retained.

Dehulling machines are known which are conventionally provided with a stationary hollow cylinder, whose inner face is provided with a rough lining of abrasive material arranged to cooperate with an internal blade arrangement. In this machine the cereal grain is thrown against the casing surface and hull parts are drawn off by a powerful air current. An improved version of such machines is constituted by multi-chamber dehulling machines with adjustable intermittent loading, whose throughput and efficiency are better than the first type of the dehulling machine mentioned. Furthermore brush or polishing machines are known in various forms which remove loose hull parts on the grains.

In previously known grain cleaning methods the cereal grains was purified and cleaned to remove all foreign bodies which accumulated in the course of harvesting in numereous various cleaning machines, and milled. Such machines include not only the dehulling but also sifting machines, sieving machines, sorting machines, washing machines and impact mills for destroying insects.

One object of the invention is to provide a method and a device which not only perform the dehulling operation but also carry out other cleaning functions for which to date several separate pieces of equipment were required.

A further object of the invention is the provision of a relatively simple and reliable machine which by the replacement and setting of various relatively moving parts can be adapted to the particular type of cereal grain or seed to be treated. Furthermore the machine should also be able to clean seeds such as soya beans, peas and other leguminous products.

A still further object of the invention is the provision of a machine which while having a compact construction and, more particularly a short axial length, guarantees satisfactory cleaning.

In accordance with the invention a method for cleaning grains and seeds for the removal of spikes on the tip of the grain or seed and woody fibrous layers is carried out in such a manner that the grain is supplied to the radially inner section of the outer end face of rotating drum and from this position is conveyed by centrifugal force to a gap which narrows in an outward direction, and after this the material to be cleaned is caused to move in a direction parallel to the axis of rotation and is passed into an annular gap delimited on the inner side by the casing of the drum and from this position the material to be cleaned is passed towards the other end face of the drum and removed in an axial direction. On the path extending from the direction parallel to the axis residue such as husks can be removed radially in an outward direction into an annular face by sieve arrangements from whence they can be drawn off.

The material emerging at the end face is freed of foreign bodies by sifting and cyclones. The cleaning method can be carried out in one stage though, if necessary, it is possible to provide several stages arranged in series, the construction of the machine in the individual stages being identical and it being possible to carry out necessary modifications of the cleaning procedures by setting parts of the machines.

An apparatus or a machine for carrying out the method can comprise a drum, which is for take up of the material arranged to leave a gap between an end face on it and a fixed radial wall, the drum also being arranged to leave a radial gap between a peripheral face on it and a housing part, a connection such as a curved connection being provided between the two gaps.

The drum is preferably made so that it can easily be removed and on its side adjacent to the inlet gap is provided with a coating for instance of hard rubber which is arranged to cooperate with a corresponding coating on the stationary housing so as to form with it a gap which narrows in the outward direction. The drive shaft carrying the drum can be provided with axial biasing means so that the material to be cleaned in the gap which extends in the radial direction is subjected to a pre-set axial pressure.

By the cooperation of the individual parts in the manner described below the advantages of the invention are obtained, as appears more particularly from the description of the specific embodiment. Such a specific embodiment is now described with reference to the accompanying drawings.

FIG. 1 is a diagrammatic view of two stages connected in series, each stage comprising a cleaning machine or device constructed in accordance with the invention.

FIG. 2 is an axial section of the cleaning or dehulling machine in accordance with the invention.

FIG. 3 shows, on a larger scale, the charging part of the machine shown in FIG. 2.

FIG. 4 is a section, perpendicular to the axis of rotation, of the end face of the drum.

FIG. 5 is a partial view of a housing part surrounding the drum with a clearance.

FIG. 6 is a section of the housing in accordance with a slightly modified embodiment of the invention, in a view corresponding to FIG. 5.

FIGS. 7 and 8 show various slightly modified embodiments of the frictional or cleaning coatings or claddings mounted on the end face of the drum.

FIG. 9 is a radial section of the drum or rotor.

FIG. 10 is a view of one beating knife mounted on the outer side of the rotor or drum.

FIG. 11 is a section on the line XI--XI of FIG. 10.

FIG. 12 is a view of the beating knife looking in the direction of the arrow XII in accordance with FIG. 10.

Referring now to the drawings and more particularly to FIG. 2, it will be seen that the machine comprises a horizontally arranged shaft 10 which carries a drum 12 or rotor. The part of the shaft 10 extending to the right in terms of FIG. 2 is carried in the housing by means of bearings 14 and 16 and at its other, rear end, is carried in a bearing 18 arranged in a housing lid 20. A helical spring 22 arranged on the shaft urges the shaft in the left hand direction in terms of FIG. 2. At its right hand end the spring 22 abuts against a housing 24 fixed in the housing while its left hand end abuts against a ring 26 which can be shifted axially in a recess in the housing. The ring 26 is connected by means of a thrust bearing 14 with a ring 28 fixed on the shaft 10.

The axial position of the shaft 10 and thus of the drum 12 or rotor in relation to the housing can thus be set by means of the spring loading device which is shown in the right hand part of FIG. 2. A ring 30 mounted on the shaft 10 bears against the bearing 16 which in turn is held in position by means of a setting sleeve 32 in an axial direction. This limits displacement of the shaft 10 by the spring 22 to the left. This sleeve 32 can be fixed in various axial positions, for example by means of a handwheel 34. Adjustment can then be carried out by means of the flange 36 extending beyond the end face of the housing. This is carried out by setting adjustment screws 38 arranged around the periphery. The shaft 10 is driven from the end 40.

The housing has a feeding opening 42 for the material to be cleaned and this opening can be closed by means of a shifting regulating flap 46 which is actuated by means of a hand lever 44. The charging opening 42 leads into an annular space 48 surrounding the shaft. This spaces open towards the end face of the drum 12 or rotor. The annular face 50 of the housing facing the end face 49 of the drum is provided with a rubber coating 52 or lining which cooperates with a corresponding rubber lining 54 on the end face 49 of the drum 12 in forming an annular radially extending gap 56 which tapers or narrows in an outward direction leading towards the outer periphery. At the same level as the annular space 48 the rotor or drum is provided with impellor or blower blades 58 which convey the material supplied through the inlet opening 42 out of the annular space 48 in a radial direction.

The left hand side of the drum 12 is closed by a cover 66 and adjacent to the end of the drum there is a conically shaped annular outlet 68 which opens into the collecting chamber 70.

The cylinder housing wall 64 is surrounded by an annular chamber 72, into which dehulled particles can pass through perforations in the cylinder 64 and which are then drawn downwards via the funnel 74. The space 70 opens into a container 78 as shown in FIG. 1, from which the cleaned cereal passes into a funnel 79 which passes it for further processing to a further suitable machine or allows it to pass from the last stage for further processing by milling. In the separator 78 there opens the suction duct 80 of an air separator 82 of the cyclone type, in which centrifugal force serves to separate solid particles from the air current, so that the air current after cleaning, free of dust and solid particles passes into the space.

FIG. 3 clearly shows the construction of the wall delimiting the gap 56. As can be seen the annular rubber disc or lining 54 is supported on a foam rubber layer 84 so that particularly satisfactory processing conditions are attained.

The outer delimitation of the gap 60 serving for changing the direction movement of the material is formed by a ring 86 which is screwed on to the fixed housing part and is preferably made of stainless steel. This ring is important for avoiding blockages and clumping together of the material. It has been found that the cause of such clumping together and blocking may be the presence of electrostatic charges if for these parts of the lining electrical insulating material is used. By the use of a ring of stainless steel such charging phenomena can be avoided reliably. Instead of a ring of stainless steel it is also possible to use a different ring which in the same manner avoids the build up of electrostatic charges.

The periphery of the drum 12 is provided with beating knives 88 and 89 in the form of strips which are screwed on the periphery of the drum. The beating knives 88 only extend over the outer peripheral part of the drum or rotor while the beating knives 89 are provided with bent end sections 90 which are fitted so as to extend over the end face of the drum. A preferred construction of these beating knives is shown in FIGS. 10 to 12. It can be seen from these figures that the knives slope upwards towards the leading edges 92 and that they are chamfered so that the trailing edges are lower than the leading edges as is indicated by reference numeral 94. The drum rotates in the direction of arrow A as indicated in FIG. 4.

The beating knives 88 and 89 can be arranged so as to be parallel to the axis on the peripheral parts of the drum, though it is also possible to arrange them obliquely or helically on the outer part of the drum.

The annular lining 54 on the end face of the drum or rotor can have a smooth outer surface, though for some applications it is convenient to provide this lining with radially extending grooves 96. It is also possible as an alternative or an addition to provide the lining with tufts of bristles or brushes 98 as is shown in FIGS. 7 and 8.

In accordance with the embodiment of the invention shown in FIGS. 2 and 3 the cylinder or casing 64 surrounding the drum can be in the form of a perforated sheet metal screen, the perforations or holes preferably being oval or elliptical. The main axes of these openings can be angularly offset between one row of perforations or holes and the next row.

In accordance with the embodiment of the invention shown in FIG. 4 the perforated casing 64 extends only for 180.degree. about the lower part of the periphery of the drum while the upper part of the periphery, also extending for 180.degree., is enclosed by a cylinder casing 100, which is internally lined with a rubber lining 102, which delimits the axially extending annular gap 62. In accordance with the embodiment of the invention as shown in FIG. 4 this lining 102 has a grooved surface 104. Instead of this in accordance with FIG. 5 it is also possible to place tufts of bristles or brushes 106 in the lining. Finally in accordance with FIG. 6 it is possible to provide a smooth rubber lining 108. The choice of the construction of the limiting faces of the annular gap is determined by the nature of the material to be cleaned. All frictional faces and other parts are mounted so as to be capable of being readily replaced having regard to the material to be treated.

The rotor or drum itself is also made so that it can easily be replaced together with the part associated with it. In order to facilitate removal the housing has openings 110 and 112 (see FIG. 2) for the insertion of suitable tools.

The setting of the axial breadth of the gap 56 is carried out in accordance with the type of material to be cleaned and also the lining material can be replaced in accordance with the material. In this respect it is also possible to construct the radial frictional lining 54 and 52 so that they present different features over various angular ranges. Thus the lining material can in part comprise a smooth annular rubber segment which is adjacent to undulating grooved or ridged material in segments. Furthermore brushes may be provided in the segments. The size of the effective annular gap 62 can be varied by replacing the beating knives with knives having a greater or lesser radial dimension.

Furthermore, instead of making alterations in this manner, the drum or rotor can be replaced by another rotor as a whole.

The dimensions of the cleaning device in accordance with the invention can be kept comparatively small. For instance for a preferred embodiment of the invention the length of the rotor is about 400 mm while its diameter is about 520 mm.

A significant feature of the invention is that the material to be cleaned is borne by an air current during the whole of its travel during the cleaning process, this ensuring an even flow without blockages or the like.

The method in accordance with the invention can be carried out on dry material or grain material which has been wetted by treatment with water in accordance with the percentage of hulls to be removed. The treatment of the grains in the device in accordance with the invention ensures good results both on grain intended for seed purposes and as regards grain intended for food purposes.

The device in accordance with the invention also ensures a very high throughput. For example with the machine in accordance with the invention 300 kilograms to 10,000 kilograms can be cleaned per hour, in accordance with the percentage of the hulls to be removed.

In the initial period of cleaning, that is to say while the grains are moved radially outwards between the stationary part and the rotating drum or annular disc, there is a dehulling, it being possible to set the gap during operation. The lining discs can if necessary have a carborundum facing.

During the second phase of the treatment, that is to say during movement of the cereal grains in an axial direction over the periphery of the drum or rotor, the beating knives or ribs continuously rotate the material and it is fed to the outlet, the hulls of the material being rubbed off by the slotted or perforated screen surrounding the drum.

In this manner a complete removal of husks or hulls can be carried out without the material which is to be milled is in any way damaged and it is nutritive value is fully preserved.

There are now described some examples of procedures in accordance with the invention using the apparatus described.

A. raw barley

Dehulling must be carried out very gently in order to ensure maximum germination for industrial use or for seed purposes. For this method an amount of water equal to 6 to 7 percent by weight is added, the wetting procedure taking place in the period of time equal to 30 to 40 minutes. Dehulling is carried out in two stages, the drum being surrounded by slotted steel screens. Six to 8 percent of the overall weight of the material is removed as hulls. The germination remains at 97 to 98 percent.

In the case of a three-stage operation removing 10 to 12 percent of the material by weight as hulls the germination amounts to 91 to 93 percent.

B. raw barley for producing of barley meal or groats

The production for brewing purposes, as animal fodder and the like is carried out in a dry process in a single stage. As a screen use is made of a combination of abrasive material and a slotted material.

C. malting barley for brewing

In this case the same treatment as "A" above is carried out but in one stage only.

D. seed oats

A single stage treatment is carried out in accordance with "A" above.

E. feeding oats

A one stage treatment is carried out which is otherwise similar to the treatment "B" above.

F. rice

Complete dehulling of short rice grains is carried out by two-stage treatment on a dry basis though the rice should not be excessively dried. The screen should be made of rubber with grooves and the discs should have the same construction.

G. rice (long rice)

The discs are opened to leave a wide gap between them, that is to say as far as possible and the speed is reduced. A two-stage dehulling treatment is carried out on the dry basis, the linear speed being reduced to at least 600 meter per minute.

H. excessively dry and brittle rice

The rice is wetted with hot water or with steam not more than 5 minutes. Dehulling is carried out in one stage and the discs are constructed as mentioned above. The speed of rotation is also decreased.

I. maize

In the dehulling of maize various points of view must be taken into account and the treatment must be made to suit the individual application. Before hulling is started, the material is cleaned mechanically or by means of air current. Dehulling is carried out of three stages with three different combinations of screens, that is to say rubber, bristles and slotted screens. In the third stage a rubber bristle arrangement extending over 180.degree. is provided while the rest of the drum is surrounded by a slotted screen. In this manner breakage of the grain is prevented and all hulls etc. are removed reliably.

J. wheat

All impurities and hairs and most bacteria together with the epidermis are removed together with insect larvae. Partial dehulling is carried out using a dry method or with addition of only 1 percent water, the maximum moisture in the wheat amounting to 13 to 14 percent. The removal of a part of the hull, up to 4 percent of the weight of the material, can be carried out without damaging the interior part of the grain to be used for flower production. The casing is as in "A" above and the method is carried out in two stages.

K. further cleaning of wheat

For the casing a combination of rubber, bristles and slotted metal being used. The material is wetted with 2 to 2 1/2 percent water so as to give a water content not exceeding 15 percent. The moistening time is 15 minutes and should not exceed 30 minutes.

L. further cleaning of wheat

A further moistening treatment is carried out lasting 30 minutes until a moisture content of 16 percent is attained. The casing is constructed as in "B" above. For hard wheats a two-to three-stage process is necessary and after two stages the second moistening operation is carried out which can last for 3 to 5 hours.

M. rye

The moisture content is increased to 14.5 percent and moistening is carried out for 20 minutes. A casing as described above under B is used and the method is carried out in one stage.

N. hard wheat for starch production

The moisture content is increased to 18 to 20 percent and a three-stage dehulling is carried out using a casing for the drum or rotor as described in B above. The material is then moistened for 5 hours so as to achieve a moisture content of 16 percent and there then follows a single stage dehulling operation. The discs are rubber discs and the casing is of the type as described above under "A."

O. soya beans

Preliminary treatment is carried out by hot water in sprayed form and after one minute cold water is sprayed in while a material is continuously moved. The maximum amount of water added should amount to 2 percent. Dehulling is then carried out in two stages and a rubber casing in combination with a slotted casing is used. The same method can be used for other types of beans. However, in the case of harder bean hulls or husks more hot water is required.

P. rape seed

This seed which has a high enzyme activity and rapidly becomes toxic requires dry cleaning from neutralization. During dehulling the temperature must be increased to 70.degree. to 80.degree. C. In this case use is made of a rubber bristle casing and the discs delimiting the radial gaps are provided with inserted brushes. Dehulling is carried out in two stages.

Q. sun flower seed

A dry dehulling is carried out using coarse abrasive on the screen and a screen part with slots. The discs are made of rubber and dehulling is carried out in two stages.

R. sesame seed

In a first stage wetting must be carried out at room temperature in 5 to 8 hours to 30 percent by weight of the seed. After the moistening the seed is mixed with cold water and the material is then past to the cleaning device in a liquid form. The discs of the cleaning device are made of rubber and the casing is rubber with inserted brushes. Dehulling is carried out by two stages and after it the seed is dried using hot air. Cleaning is carried out in an air separator. An important point in this dehulling process is that no salt water is used and that the seed after dehulling still possesses the natural while color.

The above examples are only intended to provide general indications and do not limit the method in accordance with the invention.

Claims

We claim:

1. An apparatus for the dehulling of grain material, comprising:

an outer casing; an axially extending drum positioned in said casing;

said drum having an axis about which it rotates; said drum including an outwardly extending wall; said casing including a first wall facing toward and spaced away from said drum outwardly extending wall; said outwardly extending and said first wall being shaped and oriented to define a radially extending gap between said drum outwardly extending wall and the said facing casing first wall;

said drum including an axially extending wall intersecting its said outwardly extending wall; said casing including an axial wall facing toward and spaced away from said drum axially extending wall, thereby defining an annular gap between said drum axially extending wall and said casing axial wall;

said annular gap intersecting said radially extending gap;

said casing having a grain material inlet adjacent said drum axis and leading into said radially extending gap;

impeller blower means located near said drum axis and in said radially extending gap for blowing grain material through both said radially extending and said annular gaps.

2. An apparatus in accordance with claim 1, wherein said impeller blowing means is secured to said drum and rotates therewith.

3. A method for dehulling seed material as the seed material moves between an input and an output location, comprising the steps of:

a. guiding the seed material along a path and in a first direction toward the input location;

b. imparting a propelling force for abruptly urging the seed material along a substantially straight path extending radially outward and substantially perpendicular to said first direction as the seed material passes said first location, said propelling force being the only force utilized for moving said seed material between the input and output locations;

c. imparting a circular motion to said seed material as it moves radially outward toward a second location;

d. abruptly guiding the seed material in a direction substantially perpendicular to said radial direction as the seed material passes said second location and urging said seed material to move in a circular manner as it moves linearly toward a third location;

e. confining said seed material to an annular passage space as it moves between said second and third locations;

f. abruptly urging the seed material radially outward, as it passes said third location toward the output location for collection thereof;

g. abrading the seed material as it passes between the first and third locations to remove the coverings therefrom;

h. gradually reducing the width of the path along which the seed material moves as it passes between the first and second locations to increase the abrading action; and

i. extracting the removed coverings from the annular-shaped passage space as the dehulled seed material moves toward the third location.

4. An apparatus in accordance with claim 1 in which the radially extending gap narrows conically in an outward direction.

5. An apparatus in accordance with claim 1 comprising spring means for axially loading the shaft.

6. An apparatus in accordance with claim 1 comprising rubber-like lining material on the drum and on the casing so as to line the radial gap.

7. An apparatus in accordance with claim 6 in which the lining material on the drum comprises a supporting foam elastomer layer.

8. An apparatus in accordance with claim 1 in which the radial gap merges gradually, in a curved manner with the axial gap.

9. An apparatus in accordance with claim 8 comprising a ring of a material which avoids build up of electrostatic charge and which defines the curved transition between the radial gap and the axial gap.

10. An apparatus in accordance with claim 1 comprising a perforated piece of sheet metal forming part of the casing and externally defining the axial gap, the casing further comprising means defining an annular chamber around this perforated sheet metal.

11. An apparatus in accordance with claim 1 comprising a frictional lining which bounds the axial gap over at least part of its periphery, the remaining part of the gap being outwardly delimited by means provided with holes to act as a sieve.

12. An apparatus in accordance with claim 11 in which the frictional lining extends for the upper half of the gap while the sieve lining extends for the bottom part of it.

13. An apparatus in accordance with claim 11 in which the frictional lining is of an elastomeric material.

14. An apparatus in accordance with claim 12 in which the elastomeric lining is provided with grooves parallel to the axis of the drum.

15. An apparatus in accordance with claim 12 comprising brushes inserted in the frictional lining.

16. An apparatus in accordance with claim 12 in which the frictional lining is provided with brushes, smooth material and grooved material.

17. An apparatus in accordance with claim 1 comprising beating knives arranged on the outer periphery of the drum and substantially parallel to the axis of the drum.

18. An apparatus in accordance with claim 17 in which some of the knives extend only along the outer peripheral face of the drum in a direction parallel to the axis of the drum while other knives extend additionally radially inwards over the radial end face of the drum.

19. An apparatus in accordance with claim 17 in which the beating knives are helically arranged.

20. An apparatus in accordance with claim 18 in which the radially extending parts of the beating knives so lying in a plane radial in relation to the axis of the drum are directed to points removed from the axis.

21. An apparatus in accordance with claim 20 in which downstream ends of the beating knives are higher than upstream ends of the knife.

22. An apparatus in accordance with claim 21 comprising an elastomeric lining with radially extending grooves on the end face of the drum so as to line the radial gap.

23. An apparatus in accordance with claim 1 in which the drum is provided on its radial face with a lining provided with sections with brushes.

24. An apparatus in accordance with claim 5 in which the spring means comprises a helical spring urging the drum in a direction leading to an enlargement of the radial gap.

25. An apparatus in accordance with claim 24 comprising an axially adjustable abutment for limiting displacement of the drum by the spring.

26. An apparatus in accordance with claim 1 comprising a metering flap for regulating the supply of grain to be dehulled in the apparatus, and a handlever for operating the metering flap.