Crop threshing or separating – Threshing – With bar
Reexamination Certificate
1999-08-16
2001-07-24
Will, Thomas B. (Department: 3671)
Crop threshing or separating
Threshing
With bar
Reexamination Certificate
active
06264553
ABSTRACT:
FIELD OF THE INVENTION
The invention relates in general to agricultural combines. It relates particularly to the threshing element and rotor assembly in an axial flow combine.
BACKGROUND OF THE INVENTION
In an axial flow combine, threshing takes place between an elongated rotor assembly and a cylindrical housing which encases the rotor assembly. The rotor assembly includes a cylindrical rotor drum having a plurality of threshing elements radiating from it. The threshing elements are mounted on the outer skin of the rotor.
The threshing elements may take the form of rasp bars. Rasp bars are typically arranged in a helical path around the rotor, and are fastened to the outer skin of the rotor on suitably configured brackets. Each bracket is attached to the rotor by welding, for example. Each rasp bar is removably fastened to a corresponding bracket with a fastening bolt.
During threshing, the rotor is rotatably driven at different speeds for different crops and different crop conditions. Crop material received from the combine's header passes between the rotor assembly and the cylindrical housing and is threshed by the action of the rasp bars on the crop material in that confined space. As it does so, the impact of the crop materials on the rasp bars sometimes damages the grain product being harvested. The impact of the axially moving crop material against the rotating rasp bars can abrade the crop material and the grain product, depending upon the type of crop and the rotor speed.
At the same time, the crop material and foreign objects such as pebbles and soil pieces and the like have an abrasive effect on the rasp bars. For example, rice and edible bean crops cause more wear. The rasp bar material normally becomes chipped, pitted and undercut. Uneven wear patterns frequently occur on the rasp bars. This, in turn leads to more crop damage and inefficient threshing.
Chipped, pitted and worn rasp bars may damage the grain product severely. They have to be replaced frequently to minimize damage to the grain product. Whether it is because they frequently cause damage to the grain product, or because the cost of replacing rasp bars is high, presently known rasp bar constructions leave much to be desired.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved threshing element for an axial flow, agricultural combine.
It is another object to provide an improved threshing element comprising a rasp bar made of a chrome-moly white cast iron.
It is still another object to provide a rasp bar made of chrome-moly white cast iron and having an improved shape and threshing surface configuration, as well as improved wear resistance.
It is a further object to provide a rasp bar made of a chrome-moly white cast iron having a chrome content of between 18% and 23% and a shallower face angle than known rasp bars.
It is still a further object to provide a chrome-moly white cast iron rasp bar having a threshing surface with a leading face angle or slope which is approximately 50% less than that of known rasp bars whereby grain product and rasp bar damage is minimized.
It is another object to provide a rasp bar having a leading face slope which is 60° or less.
It is yet another object to provide a rasp bar which has a leading face wall thickness nearly two times that of conventional cast iron bars and affords the rasp bar increased resistance to damage from impact.
The foregoing and other objects are realized in accord with the present invention by providing a rasp bar which is chrome-moly white cast iron. The rasp bar has a wall thickness nearly twice that of conventional cast iron bars. The angle or slope of the leading face on the rasp bar is approximately 50% less than that of any prior art rasp bar configurations. The angle or slope is preferably about 52.5° and, in any event, less than 65° and more than 45°. This configuration results in higher resistance to rasp bar impact damage and, in addition, less crop material damage.
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Case Corporation Drawing No. 1309336C1, dated Mar. 21, 1982.
Case Corporation Drawing No. 1309175C1, dated Jun. 6, 1984.
Neumann Corey
Rahe Edward N. A.
Sponzilli John T.
Brinks Hofer Gilson & Lione
Case Corporation
Lione Richard G.
Mammen Nathan
Will Thomas B.
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