DESIGN AND PERFORMANCE EVALUATION OF A MOTORISED MELON SHELLING MACHINE

ABSTRACT
A melon sheller was designed and fabricated in the Department of Agricultural and Bio-Environmental Engineering Technology, Auchi Polytechnic, Auchi. The sheller was evaluated for its performance. Tests were carried out to determine the effects of shelling speed and feed rate on the measurements of the shelling parameters. Test results showed that the rate shelling increased as the speed was increased. The efficient at shelling speed of 1400rmp, 1077rmp and 933rpm at feed rate 1000gm were; shelling efficiency of 85%, 87% and 80% and breakage efficiencies at shelling speed of 1400rpm, 1077rpm and 933rpm at feed rate of 150 gm were: shelling efficiency of 85%, and 80% and breakage efficiency at shelling speed of 1400rpm, 1077rpm and 933rpm at feed of 200gmm were: sheling efficiency of 855, 87% and 80%. Breakage efficiency of 4.2%, 2% and 1% and through put capacity of 40.80kg/hr, 38.8 kg/hr and 32 kg/hr respectively.

Background of the Study
Melon is the name of fruit of several plants that belong to the family of cucurbit. The fruit, or melons, are round or somewhat egg-shaped. They range from linch (2.5cm) to 1ft (30cm) or more across. Melon seed is very popular condiment in Nigeria local soup. It is valuable sources of oil and protein. Traditionally, oil is expressed from the seed for edible purposes while the residual cake is usually consumed as a snack. The oil can also be used in the manufacture of Margarines, soap, Pomade, Lubricant and adhesive. However, shelling of the melon seeds and of separating the seeds from the husks remains a major problem to be mechanized in moist rural areas where melon are abundantly grown in Nigeria.

The traditional methods of shelling the melon seeds one by one with hand is commonly practiced in most home and locality. The method is time consuming, drudgery, energy wasted and inflicts injury to the fingers and very painful. The production output using the traditional methods is low that points towards using other methods. Most of the mechanical shelling machines available in the country today are imported ones which are unaffordable to buy due to their high cost complexity in design and operation. In other to meet the current high production level of melon in the country, there is the absolute need to design a simple and inexpensive manual or motorized shelling machine to make melon shelling very attractive and comfortable. The present study looks at the design and performance evaluation of a motorized melon shelling machine. Efforts have been made are still being made to overcome the limitations of the traditional method of shelling melon. Odigboh (1979) developed an industrial melon shelling machine with a capacity of 150kg/hr and shelling efficiency of 95%. National center for agricultural mechanization (1995) developed a kitchen model types, it has two concentric cylinders, the internal cylinder is stationary with serrated rough surface for abrasion. Makanjuola (1979) fabricated a centrifugal types melon sheller. It works by impact force to shell melon seeds. The performance evaluation carried out indicated higher shelling efficiency at higher speeds of operation, kuku (1981) reported that moisture content affect agricultural material during shelling. He reported further that the higher the moisture content the lower the rate of shelling and for maximum shelling to be achieved, the moisture content should 13%(wb). Sharmal and Devnani (1980) carried out threshing studies on soyabean and compea. Their shoed that threshing efficiency increased with the increase in shelling cylinder speed but decreased with the increased in feed rate and concave clearance. When grain is cleaned contaminants are removed by the use of special equipment that takes advantages of differences in physical properties of various components in the mixture, Chung et al(1994). They are added that the physical properties used in making separation are size, shape, density, surface texture, terminal velocity, electrical conductivity, color and resilience.