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This invention relates to apparatus for comm inuting,
separating or de-husking plant material such as grains and seeds.

Existing machines for this purpose (known in the industry as impact grinders) typically comprise a rotor which is mounted on a herizontal axle in a fixed casing. The casing has an inlet above the rotor and an outlet below and
material which is fed into the machine is processed by the rotor impacting it against the internal surface of the casing. An example of this type of machine is describec and illustrated in Australian Patent 521100. One disadvantage with such existing apparatus however is that the outer faces of the striker bars on the rotor which propel the material against the casing become worn due to abrasion from said material. This eventually reduces the efficiency of the mill to the point where it has to be dismantled and the bars either rotated or replaced.

It is therefore an object of this invention to ameliorate the aforementioned disadvantages and accordingly this
invention discloses an impact grinder having a casing with a rotor disposed therein on a preferably horizontal axis, an inlet in said casing located above the rotor and an outlet below, wherein said rotor comprises a housing with a plurality of striker bars rotatably mounted thereon so that wear on said striker bars is evenly distributed over their circumferential surface.

One perferred embodiment of this invention will now be describee with ref erence to the attached drawings in which:

Figure 1 shows a perspective view of an impact
grinder according to this invention,

Figure 2 is a view similar to figure 1 but with
the front plate of the grinder housing cut away
to show the seed material passing therethrough,

Figure 3 is a perspective view of the rotor for
this grinder, and

Figure 4 is a cross-sectional view along the lines
A-A of figure 3.

Referring first to figures 1 and 2 the apparatus basically comprises a housing 1 with ribbed internal surfaces 2 and a rotor 3 which is turned on a axle 4 by any suitable type of engine (not shown). The plant material to be processed enters through the hopper inlet 5 and is impacted against the internal ribbed surface 2 by the striker bars 6 of the rotor whereby it is comminuted, separated or de-husked as the case may be. After processing in this manner the material is then passed out through outlet 7. As best illustrated by figure 2 a feed control mechanism may also be incorporated into the inlet chute 5. This may comprise a transverse motor driven impeller 7A which is located between upper and lower baffle plates 7B and 7C. The material in the hopper is cnannelled onto the impeller fror the upper oaffle as shown and the preselected rotational speed of said impeller serves to meter tne flow of seed across the lower baffle 7C and into the grinder.

Preferably the rotor 3 is of a squirrel cage design (see figures 3 and 4) and comprises thirty-two striker bars 6 disposed in a staggered arrangement around the periphery of support plates 8 and 9. There, are four such plates mounted along the length of the axle 4 and secured thereto by means of flanges 9A and bolts 10. As best shown in figure 4 each of the striker bars extends completely through bores 11 in the centre two plates 8 and the ends seat in caveties 12 in the outer plates. In accordance with this invention the bores 11 and cavities 12 are dimensioned so that the striker bars while being held firmly against any significant radial or axial displacement are nevertheless freely rotatable with respect to the support plates.

Such a construction ensures that the wear which in prior art machines occurs primarily on the outer surface 13 of each bar is now evenly distributed over its circumference. Such distribution occurs by virtue of the fact that as the outer surface 13 wears away the mass of the bar becomes asymmetric and the centrifugal force generated by the rotation of the rotor tends to turn the bar so that the heavier and hitherto unworn inner surface 14 moves out toward the periphery of the support plates.

By virtue of this automatic adjustment of the strike bars it is envisagedthat the service lifre and efficiency of these machines between overhauls can be greatly increased.

It is to be understood however that the particular embodiment described is only the currently preferred form of this invention and a wide variety of modifications may be made which would be apparent to a man skilled in the art. For example the number, spacing and relative size of the striker bars and support plates as well as the material from which they are constructed could all be varied according to application or design preference. Also while the striker bars shown are hollow to reduce wieght the invention also extends to the use of solid bars and/or bars of other cross-sectional shapes.