The Compressive Wafering of Grass Hay (II)

Wafering of Italian-Ryegrass by Roller-Die Method (I)

Abstract

The roller-die type apparatus reported in preceding paper was modified. The compressive characteristics on chopped hay of Italian-ryegrass were investigated under various moisture contents and die temperatures for five different wafer dies and two different cube dies. The important conclusions of this investigation were as follows:
1. When hay was chopped at about 3cm in length, wafer was hard to be stratified and sometimes extruded, being divided lengthways into two or three.
2. The senses of sight and of touch could be a good index for the valuation of durability of wafer.
3. Wafer formation index I's were I 100°C>I 80°C>I 25°C, and I 20%>I 25%≥I 12%>I 30%>I 40%>I 50%, with the variation of die temperatunes and moisture contents of hay, respectively. The wafer formation index of rehydrated hay by spraying was considerably lower than that of ground-dried hay when the moisture content was the same. This phenomenon might be caused by water acted as a lubricant on the dies.
4. When moisture content of hay was higher than 20%, temperature of wafers did not rise above 105°C even if die was heated to 105°C or higher. When the moisture content of hay was 20% and die temperature was 20°C, wafers were not extruded in any dies.
5. Vertical compressive force V on roller shaft and horizontal tractive force H of die at dried hay of 20%m. c. increased rapidly with the increase of length of die, while the waferability increased little, and the wafer clogged in the die chamber frequently. For the wet hay of 40-50%m. c., on the other hand, long wafer die's resistance forces were nearly equal to those of short dies but waferability was advanced remarkably with the increase of the length of die. Therefore, the length of die had a significant effect on waferability at high moisture contents.
6. The waferability of tapered dies (No. 4 and 7) with smaller V and larger H, in which the width was 15% shorter than the straight dies (No. 1 and 6), was one rank lower at 20%m. c. but one rank higher at wet hay, probably due to transudation of some water.
7. The die (No. 5) inclining at an angle of 15° had smooth feeding of hay, required comparatively short passing time t through die chamber, and formed stratified wafers. At 20%m. c. its V value was very small but its waferability was equal to or slightly less than that of straight die. With the hay of high moisture content, its H value became large and its waferability was one rank lower than that of straight die.
8. Cube dies (No. 6 and 7) had bad feeding rate of hay and large t value as compared with wafer dies, and cubes were not extruded at 20%m. c. even when heated. The V and H values and waferabilities of cube dies were almost the same as those on wafer dies above 20%m. c.
9. V and H values decreared rapidly when m. c. increased and the maximum values were obtained at about 20%m. c.
10. The difference between vertical forces (or horizontal forces) by the shapes of die was increased with the decrease of moisture contents.
11. Passing times for tapered dies, increased at high moisture contents but passing time for other dies increased and their feeding rates of hay decreased generally with the decrease of moisture contents.
12. In case of the roller die passing time and feeding rate of hay varied with the experimental conditions, and the feeding rate had to be improved.