Doctoral Dissertations

Date of Award

3-1979

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Biosystems Engineering

Major Professor

Bobby L. Bledsoe

Committee Members

John I. Sewell, Ray Holland, Zachary A. Henry, Fred D. Tompkins

Abstract

A large quantity of soybeans have been lost each year due to shatter caused by the cutterbar and other combine header components. A band blade cutting device was designed, constructed, and tested for effectiveness in reducing these shatter losses. The electrically driven band ran in a rectangular path around four 20.3 cm (8.0 in) diameter wheels. The blade thickness was limited to 0.05 cm (0.020 in) or less due to the stresses induced when traveling around the wheels. The blade return path precluded the use of a conventional reel. A reel having bats carried by chains was devised. The new header was attached to and powered by a Chain Machine Company SP-50 plot combine.

Laboratory tests were performed in which a plant carriage system was used to feed erect plants into the stationary headers of both the conventional and the experimental machine. An abrasive "Grit-edge" blade was used. The band-blade header was compared to the conventional cutterbar header on the bases of percent shatter loss, uncut (lodged and stubble) loss and total loss. Four levels of band blade speed between 460 and 910 m/min (1500 and 3000 ft/min) were used. Simulated ground speeds were set at four levels between 3.2 and 6.4 km/hr (2 and 4 mi/hr) while testing the band blade header. The conventional header was tested at 330 cycles/min and a simulated ground speed of 6.4 km/hr (4 mi/hr). Response surfaces of shatter, uncut, and total losses as a function of blade speed and ground speed of the band blade header were developed. Blade speeds of 910 m/min (3000 ft/min) reduced shatter below the levels found in the conventional header for all ground speeds. However, the uncut and total losses were not lower for the band blade header.

Five high speed cinema films were taken as part of the laboratory tests. The author concluded from the shatter tests and film studies that the abrasive blade did not cut rapidly enough. The abrasive surface did not positively engage the plant fibers. A high force normal to the cutting edge was required to aid the cutting action. The plants were excessively disturbed.

A toothed blade was selected for field tests after consideration of the laboratory results. A spring steel blade having a tooth pitch of 5.1 mm (5 teech per inch) was selected. Shatter, stalk, lodged, and stubble losses were collected from a 137- x 91-cm (54- x 36-in) area after the combine header had passed. Five blade speeds between 610 and 1830 m/min (2000 and 6000 ft/min) were used. Ground speeds were set at five levels between 1.6 and 4.8 km/hr (1.0 and 3.0 mi/hr). Moisture and maturity of the beans were monitored. The field tests were not sensitive enough to measure all effects adequately due to insufficient replication. The linear component of ground speed was found to significantly effect shatter at the 90 percent level of probability. Comparison of means between the band-blade header and the conventional header showed that shatter, lodged, and total losses were not different, but stalk and stubble losses were lower for the band blade header. The cutting action was smooth. Little plant disturbance was observed during operation in the field.

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