DEVELOPMENT OF AUTOMATIC TRANSPORTATION SYSTEM FOR RICE SEEDLING PRODUCTION

Transcription

1 DEVELOPMENT OF AUTOMATIC TRANSPORTATION SYSTEM FOR RICE SEEDLING PRODUCTION Yi-Chich Chiu 1 ; Din-Sue Fon 2 1 Biomechatronic Engineering Department, National I-Lan Institute of Technology, Taiwan; of corresponding author: yichiu@mail.ilantech.edu.tw 2 Bio-industrial Mechatronics Engineering Department, National Taiwan University, Taiwan; dsfong@ccms.ntu.edu.tw ABSTRACT The objectives of this research were to develop an automatic tray transportation system for rice seedling production including input and output operations. For trays transportation inside the hardening field, a low-cost but compact transport gantry was developed to convey the seedlings and trays in and out of the field. In input operations, an automatic transportation system was constructed by linking the automatic pallet loading/unloading machine for seedling trays, tray de-stacking machine and tray loading/unloading machine. The seeded trays can be automatically transported from stacking area in seeding room to hardening field and arranged in rows on the field for hardening. The experimental result showed that the system capacity is about 1,300 trays/h. This system also works well for 3-tray piles placements in rows on the field. In output operations, the system automatically transports the seedling trays with rolled-up seedling mats for further truck transporting. Keywords: Rice seedling, Automatic transportation, input operations, output operations. INTRODUCTION Rice is a staple crop in Taiwan. Traditional rice cultivation is to transplant rice seedlings to the paddy field by transplanter. There are about 900 rice seedling centers providing almost all of the rice seedlings to the farmers. Producing seedlings is an important stage in rice production process. The work of rice seedling nursery mainly consists of four parts: seeding, input operations, seedling growth, and output operations. The seeding operations include supplying trays, soil filling, water spraying, sowing, pesticide spraying, and soil covering. The seeded trays are stacked in a conditioning room for about three days to speed up sprouting and then moved to the field for acclimatisation and further growth, which concludes the input operations. The seedlings will eventually grow with their roots matting in the tray and, at the completing stage, they can be rolled into a cylindrical shape for transportation and later transplanting. The output operations include rolling the seedling mats, collecting the rolled mats from trays, conveying, and stacking them on the truck for transportation.

2 The work involved in the nursery operations is seasonal, labour-intensive and time-consuming. At present in Taiwan, lack of farm labour has increased the cost of operation and has necessitated the mechanisation of the process. Thus, the objectives of this research were to construct the automatic tray transportation systems for rice seedling production for seeding, input and output operations. MATERIALS AND METHODS 1. Transport gantry The transport gantry is mainly an inverted-triangular truss on which two parallel V-belts are equipped to convey the seedling trays(figure 1). Each truss is about 25 m long and can be extended to more than 100 m in length by connecting to one another if necessary. The gantry moves on and is also supported by two parallel rails embedded in concrete foundations, with a cross-section of 0.4 m in height and 0.6 m in width. The specifications of gantry member was shown in Table 1. It is constructed of 4 types of commercial pipes, all made of S45C steel. Figure 1. Main structure of transport gantry Table 1 Specifications of the structure members Member Square pipe Circular pipe 1 Circular pipe 2 Circular pipe 3 Description Construction steel Construction steel Construction steel Construction steel Dimension, mm pipe, pipe, Do60.5 pipe, Do42.7 pipe, Do34.0 Thickness, mm Weight, kg f /m Area of Cross-section, cm Moment of Inertia, cm Yield Stress, kg f /mm 2 Tensile Stress, kg f /mm

3 2. Tray loading/unloading machine Riding on the top of transport gantry, an automatic tray loading/unloading machine has been developed to pick the trays from conveyor and arrange them in order onto the field for hardening. Using the same machine, the process can be reversed by picking grown seedling trays from field orderly and placing them back onto the gantry conveyor. To the truck, the seedlings are ready for transplanting. This machine is driven by motors, with a programmable logic controller (PLC) to process the sequential controls. For saving the tray conveying time, the speed of conveyor is controlled by changing its frequency through a programmable converter. The detailed description of this machine could refer to Chiu and Fon (2002). 3. Seedling-mat rolling machine The seedling-mat rolling machine enrolls the seedling mat from a 30 by 60 cm tray into a shape like a cylinder. The motion of rolling includes three functions: pulling, rolling, and forming. Three French curve plates, the seedling-mat pulling plate, the seedling-mat rolling plate and the seedling-mat forming plate are the main components that accomplish the actions. All plates are pneumatic activated with a programmable logic controller. 4. Seedling-roll relocating machine The seedling-roll relocating machine that can collect three seedling-mat rolls at a time into a tray is the one that we hope to replace the conventional labour. The machine is composed of two sets of grippers that temporarily hold the seedling rolls. At the beginning, the first gripper set holds the first roll coming from the seedling-mat rolling machine, and then the second holds another. After the third roll set in its position, the grippers lower the first and second ones onto the tray that contains the third roll and finalize three seedling rolls in a tray. Two pneumatic cylinders drive the gripper sets, one for the vertical motion of the grippers and the other controls the jaws of the gripper. 5. Seedling diverter and seedling collector In output operations, three seedling-mat rolling machines were arranged in parallel to meet the system capacity. For this purpose, a diverter and a collector were designed at both ends to adjsut the tray flows. The diverter located at front of parallel flows will switch the one-way flow into three in sequence using a PLC controlling unit (Figure 2). The collector at the end of three flows functions as a queuing apparatus that arranges the finished rolls back in line and moves them forwoard for further relocating (Figure 3). Both diverter and collector shape like, in which each consists of 4 sectional conveyors, driven by a 1/4 horsepower motor. Limit switches are installed for each line to detect the tray comings by processing the sequential controls.

4 To roller 3 To roller 2 To roller 1 Seedling enter Figure 2. Design of seedling diverter From roller 1 From roller 2 From roller 3 Seedling rolls out Figure 3. Design of seedling collector RESULTS AND DISCUSSIONS 1. Automatic input operations In input operations, the seeded trays are transported from stacking area of seeding room, via conveyors, to the tray loading/unloading machine. This machine then automatically picks up the trays in sequence and set them on the nursery field in rows, with no space between trays (Figure 4). As working in one-way direction, the tray-unloading machine must return to the end of gantry first to start the next row. The experimental result shows that the whole system can be run automatically in an open field for seedling preparation with a system capacity of about 1,300 trays/h. For some large rice seedling centers that require pile placements, this system also work well for 3-tray piles in rows on the field. Workers can then distribute the piles on the field in three-row width. Working on this mode, the system capacity can reach about 3,900

5 tray/h, if accompanied by two placement workers. Figure 5 shows the results for the tray loading/unloading machine that has arranged three-tray piles in lows on the nursery field. Figure 4 also shows transport gantry that was developed in this study. It consists of trusses on which two parallel V-belts are equipped to convey the trays. The gantry moves longitudinally on top of two parallel rails. The tray loading/unloading machine sets on the gantry and moves along. The gantry used the off-the-shelf standard steel pipes as its structure members, only weighing about 26 kg f /m. The transport gantry features cost-effective, compact and easy for maintenance in comparison with the conventional one. Figure 4. Automatic input operations. Figure 5. Arranging three-tray piles in lows on the nursery field by a tray loading/unloading machine. 2. Automatic output operations Figure 6 shows the schematic of seedling enrolling system. The whole trays with grown seedling-mat in the nursery field were picked up by the tray loading-unloading machine (Figure 7), and then conveyed to a diverter which converts the tray flows into three channels (Figure 8). The diverter automatic switches the incoming trays to one of the three parallel rolling machines where the seedling mats were enrolled into cylindrical shapes (Figure 9). The finished rolls were then put back into order through a collecting section (Figure 10). The relocating machine sits at end of line flow will then put the finished rolls by three in a tray (Figure 11), which were transported to a waiting truck through slant conveyor. On the truck, workers handle the seedling-rolls for further transportation. Experimental results showed that the tray loading/unloading machine worked satisfactorily at 1,500 trays an hour, while the relocating machine 1,200 seedling-rolls an hour. Unfortunately, each seedling-mat rolling machine only works at a rate of 362 seedling rolls per hour, one third of the capacities the relocating owns. For the present system, three sets of rolling machines are used, merely reaching 1,000 rolls/h. The whole automatic seedling output system consists of transporter gantry, conveyor sets, tray loading/unloading machine, seedling diverter, seedling rolling machine sets, relocating machine, etc. It is a heavy investment so far as a farm business like nursery center is concerned. An easy way by compromise is that the accompanying workers enroll and collect the seedling-mats, three rolls in a tray, on the field first and the tray loading/unloading machine is

6 then called to pick them up onto the conveyor of transport gantry (Figure 12). This arrangement will enhance the system rate high above 3,900 rolls/hr. Figure 6. Schematic of Automatic enrolling system for rice seedlings. Figure 7.Automatic tray loading operations. Figure 8.Seedling diverter and three parallel rolling machines. Figure 9. Seedling-mat rolling operations. Figure 10. Seedling collector and relocating machine.

7 Figure 11. Seedling relocating machine places three seedling-rolls in a tray. Figure 12. Tray loading/unloading machine collects the trays with three seedling-rolls onto the transport gantry. CONCLUSIONS The automatic transportation systems for rice seedlings have been successfully developed for tray input and output operations. For input operations, the tray loading/unloading machine, riding on a newly designed transport gantry and acting as a loading device, can automatically transport and arrange the seeded trays in rows in the nursery field at a rate of more than 1,300 trays/h. The working capacity of the same machine, if only used for tray-pile loading with the tray arrangement done by workers, will increase to 3,900 tray/h. For output operations that combine the equipment including transporter gantry, conveyor sets, tray loading/unloading machine, seedling diverter, seedling rolling machine sets, and relocating machine, the system throughput will reach about 1,000 seedling-rolls/h. ACKNOWLEDGEMENTS The authors wish to acknowledge The Council of Agriculture of the Republic of China on Taiwan for its finical supports. Thanks are also extended to Dr G. J. Wu, Mr. C. S. Wang for their assistance. REFERENCES 1. Fon D S and Chiu Y C. Automation on seedling production for rice nursery centres. Project report. Department of Agricultural Machinery Engineering, 1997, National Taiwan University, Taipei. 2. Chiu Y C and Fon D S. An analysis on the transportation operational system for rice nursery centre in Taiwan. J ournal ofagricultural Machinery, 1998, 7(1), Chiu Y C, Fon D S and Chen L H. A simulation model of a seeding system for rice nurseries. J ournal of Agricultural Engineering Research, 1998, 69, Chiu Y C, Fon D S and Chen L H. Predicting the production schedule of paddy-rice nursery. Transactions of the ASAE, 1999, 42(2), Chiu Y C, Fon D S and Chen L H. Simulation of conveyor transport operations using a gantry system. J ournal of Agricultural Engineering Research, 2000, 75,

8 Chiu Y C and Fon D S. Development of an automatic rolling system for rice seedlings. J ournal of Agricultural Engineering Research, 2000, 76, Chiu Y C and Fon D S. Simulation of automatic tray-unloading operations for rice seedlings. Biosystems Engineering, 2002, 81(2), Chiu Y C and Fon D S. Simulation of automatic output operations for rice seedlings. ASAE paper , 2002, J oseph, MI.