Studies on Hay Conditioning by a Pair of Rollers (I)

Effects of Roller Design and Roller Material

Abstract

The effects of the set of rollers design and material in a hay conditioning process was investigated. In laboratory scale tests the upper rollers position was fixed, while the lower rollers were mounted on a pivoted support which allowed to apply a force directly on upper rollers by the hydraulic system. Both rollers could operate independently. Six sets of rollers combination, with 220-240mm in diameter and 100mm in length, were designed as presented in Table 1. The loading force of the rollers was 23-90kg while the speed was 30-120rpm. After running the samples through the conditioning rollers, samples were placed in the drying chamber (30°C, RH 65%) to obtain the results of the drying test. Freshly cut Orchard grass and Red clover were used in the tests. The results were as follows:
1) Mechanical dewatering response of the conditioning rollers was affected by the rollers material (steel and or rubber). For the first cut the set of steel rollers gave maximum drying for Orchard grass and Red clover, while a combination of steel and rubber rollers provided minimum drying for both forage crops.
2) Dewatering response had a trend to increase by an increase of the rollers loading. However the moisture loss was low, hence often could be neglected.
3) The rollers treated grass had a higher rate of drying than that of untreated grass. The relation of moisture content to drying time was a linear response, from the initial to a given moisuture level, when it was plotted on a semi-logarithmic graph and expressed by a variant exponential equation.
4) In case of a set of smooth rollers the highest rate of drying was achieved by a combination of steel and rubber rollers for Orchard grass and by a set of steel rollers for Red clover, while a set of rubber rollers provided the lowest rate of drying for both forage crops.
5) A combination of ribbed steel and smooth rollers of steel or rubber, or a set of corrugated rubber rollers provided a high drying rate only by the use of corrugated rubber rollers for the first cut of the Orchard grass and Red clover, while for the second cut the drying rate was only slightly affected by the choice of the rollers.
6) The rate of drying was only slightly affected by the number of the ribs and corrugation of the rollers applied.