Agricultural Engineering

Transcription

1 Agricultural Engineering AN AUGER HARVESTING SYSTEM ITOR RECUMBENT SUGARCANE Joe E. Clayton USIIA Belle Glade, Florida ABSTRACT Sugarcane which has fallen and intergrown is very difficult to harvest with machines. The heavy growth and the inability to top the cane have caused chokages and large hp consumption. An experimental harvesting system was designed which eliminates gathering chains and provides slowly revolving components for handling the cane. The cane is chopped into short lengths immediately as it is cut to enable proper conveying. Two 20-in. diameter augers with 12-in. core and 12-in. flight pitch are mounted on the side of a tractor. A conventional 36-in. diameter rotating disc with segments cut the cane at the ground. The auger flights on the 6-ft wide pickup system lay any standing cane toward the uncut field as 1 row is harvested. Fingers on the lower auger lift the cut cane from the ground, and it is fed between the 2 augers. The intermeshing flights of the 2 augers cut the cane into short pieces as it passes between the augers. These flights are sharpened and hardened for operation in sugarcane. With the 12-in. auger flight pitch, about 75% of the cane pieces are between 12 and 24 in. in length. These auger harvesting devices demonstrate that recumbent sugarcane can be harvested with slowly revolving components. Little trash wrappage occurs with the large diameter augers. Pickup efficiency is good on flat cultivation, but additional pickup assistance would be needed for ridges or furrows. INTRODUCTION Sugarcane that is tangled or recumbent has resisted efficient and economical mechanical harvesting for many years. When the recumbent growth is combined with muck or wet soil and possible hurricanes, the problem seems insurmountable. In many areas the harvested product is being compared with hand-cut cane, which makes results seem poor. Measurements in a recumbent field in Florida, after burning, showed that 81.6y0 of the cane was below 1 ft above ground (Table 1.) This was calculated by weight in a field yielding 27.6 tonslacre. A similar experiment in tangled cane in Louisiana indicated 55y0 of the weight of 1 variety was below 1 ft, with 5 other yarieties averaging 14.1% below 1 foot (Table 2). When the cane is intergrown, it is impossible to erect without uprooting or breaking the stalk. If the stalks cannot be erected for topping, the trash content of the cane is increased drastically. Attempts to harvest recumbent cane were made before the turn of the century. Several harvesters were operated in Florida about 1930, and some were tried in Hawaii also. These harvesters encountered chokages, had many mechanical problems and were abandoned. In addition to the problem of topping recumbent cane, properly chopping

2 68 AGRICULTURAL ENGINEERING Table 1. Amount of cane in I-ft increments above ground, Belle Glade, Florida, March 20, Amount in increment Area (in.) % Tonslacre Above Table 2. Percentage of cane at intervals above top of row for 6 varieties, Houma, Louisiaila area, October-November, Variety Segmeilt CP CP CP (ill.) Above CP NCo CP the mat of crooked stalks is difficult. The long pieces of cane are more difficult to convey and they reduce the load density. PROCEDURE Preliminary investigation showed that' Florida cane could not be erected without uprooting or breaking the stalks. It was estimated that only about 25% of the stalks were erect so that they could be topped. A mat-type pickup system was needed that would lift the cane and cut it at the ground and at the side. The cane should be gathered at the same time as it is cut from the ground. Primary emphasis was on a simple, slow-moving, durable pickup system that had a low power requirement. A harvesting system using two horizontal augers was designed and constructed to harvest 1 row of cane (Fig. 1). The augers were positioned across the row, with the lower auger lifting the cane. The flights on the upper auger knocked any standing cane across the row, and the overlapping end discs cut the row being harvested apart from the field. The fingers on the lower auger lifted the cane from the base cutter, and it was cut into short pieces by the sharpened flights of the meshing augers. The pickup fingers were bolted to the augers so that experiments could be made to determine the proper spacing. The 2 augers were of 20-in. diameter with 12-in. flight spacing and 12-in. core. The pickup system was 6 ft wide, and the augers turned at rpm. They were driven hydraulically for variable speed, easy power measurement and reversing. The harvesting unit was side-mounted on a 4-wheel drive tractor and equipped with conveyors.

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4 70 AGRICULTURAL ENGINEERING A conventional circular blade was used for cutting the cane at the ground. Preliminary research had resulted in recommendations for increasing the speed and equipping circular l?lades with sections. The system was operated in cane of tonslacre and was satisfactory for cane grown with flat row profiles. With the 12-in. flight pitch, 73.4% of the cane pieces were less than 24 in. long (Table 3). Some pieces were less than 6 in. long, and some were 3-5 ft long due to the Table 3. Lengths of cane harvested with auger components in field experiments, Belle Glade, Florida, February 15, Measured lengths Harvested cane (in.) (%) position of the mat. This cane had an average density of 15.6 lb/cu ft when loaded into a wagon. The augers consumed only 6-8 hp to harvest 1 I-ow of cane, but 40 hp was available. Each base cutter used hp, with the arrangement using diameter discs. The capacity of this system was tdnslhr in burned cane. Field tests were usually conducted at 2-3 mph, although a top speed of 5.75 mph was reached. The faster speeds helped to lift the mat into the machine. A 2nd unit, using a 30-in. diameter upper auger and an 18-in. diameter lower auger, was designed and tested (Fig. 2). The clearance between the augers was 11 in., and they were 6 ft wide with the same features as the other unit. The lengths of cane pieces cut with the 30-in. diameter system averaged 21 in., with pieces ranging from 8-57 in. Similar results with the 20-in. diameter augers indicated an average length of 14.6 in., with a range of 4-48 in. The upper auger was pitched forward so that the flights contacted the erect stalks to lay them over before they were cut from the ground. The pickup efficiency and capacity of this unit was greater than the 20-in. diameter augers. The capacity was never reached in burned cane, but it was estimated to be 120 tons/hr., The requirement was 18 hp in average operation with 40 hp available for overloads. The single 36-in. diameter base cutter used 16 hp. This system was operated in unburned cane with satisfactory results. The auger core should be 6 in. in diameter or larger to prevent wrapping of trash. The type of cut with the overlapping auger flights was highly satisfactory. The blades sheared the cane from each side, and the cut pieces were free to move away from the mat. There was no material taken out of the cut, and there was little mashing of the ends. Sections were riveted to 1 of the parting blades at the end of the auger to positively move the cane through the blades. DISCUSSION The design of the auger harvesting system demonstrated that recumbent sugarcane could be harvested with simple, slowly revolving components. The

5 JOE E. CLAYTON AUGER fume Fig. 2. Auger harvesting system using 30-in. diameter upper auger and 18-in, diameter lower auger, side view. :ir,

6 72 AGRICULTURAL ENGINEERING cane was positioned, cut at the ground, side-cut, harvested and chopped with a minimum of handling. There were no chains or sprockets to choke and wear. Horsepower required to harvest and chop was in the range of 6-18 for the I-row system. The augers were designed with +-in. clearance between the overlapping cutting edges. Results indicated that the fibrous cane stalk could be cut with +$-in. clearance, but some leaves would not be cut. The augers were durable, were not vulnerable to rock damage and dropped some unwanted materials such as clods and suckers. There was no pretopper operated with this harvest system since only 25y0 of the stalks were erect enough to top. A pretopper could be used but the harvesting system being planned used bulk cleaning of the short pieces. The base cutting disc, auger feeding system, chopping system and cane discharge were evaluated with a high-speed motion picture camera. With camera speeds of pictures/sec, the action of the components was slowed for observation and motion analysis. Changes were made as a result of this analysis. REFERENCES Falkiner Cane Harvester International Sugar J., p Duncan, R. A Developmelit of a sugarcane harvester. Agri. Engineering, 31 (2). Duncan, R. A Sugarcane harvester development in Hawaii. Proc. ISSCT, 11: Clayton, J. E Research on systems for harvesting and cleaning recumbent sugarcane. Sugar y Azucar. July.