| 摘要 |
PROBLEM TO BE SOLVED: To obtain crushed stones mixed with sand at a constant ratio in a dam filter material producing method, even if the load of a crusher is fluctuated. SOLUTION: In a dam filter material producing method, when the load of a crusher 6 is fluctuated, a conveyed amount of a first belt conveyor 15 for conveying crushed stone obtained by the crusher and a conveyed amount of a second belt conveyor 18 for conveying purchased sand are detected, and signals indicative of the detected values are supplied to a fuzzy controller to calculate a mixture ratio. Then, the thus calculated mixture ratio is compared with a proper constant mixture ratio of sand and crushed stones, which has been set beforehand, and speed-varying control is carried out by issuing a speed command to a discharging vibrational feeder 17 of a sand bottle 16 where the purchased sand is stored, in order to eliminate the difference between the mixture ratios, to thereby discharge the purchased sand so as to correspond to the amount of the conveyed crushed stones conveyed by the first belt conveyor. The purchased sand is conveyed by the second belt conveyor to be discharged on the first belt conveyor, on which the sand is mixed with the crushed stones at the proper constant ratio.
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