| 摘要 |
PURPOSE:To reduce the shaking speed of a belt in the width direction by obtaining the corrected value of the siding speed of a belt, determining the quantity of deviation to determine the deviating position, and judging the deviating position abnormal when it is beyond a defined range. CONSTITUTION:When a photosensor S1 is turned on due to the first zigzag movement of a belt 1, a control part makes a zigzag-movement correcting roller deviate in a direction to be corrected, by a define quantity. Then, as a photosensor S2 is turned on, the roller is made deviate by twice the defined quantity in the opposite direction, and the trend of deviation is obtained from the difference in siding speed between both deviations, to carry out initial stage setting for the quantity and position of deviation. After that, the quantity of deviation is corrected in such a way that the siding speed to right and left is made equal while that the quantity of deviation is gradually reduced. In this case, it the deviating position of the zigzag-movement correcting roller is beyond a proper range, it is judged abnormal and the unit is shut down. Due to this construction, the shaking speed of the belt in the width direction can be suppressed small while preventing the damage of the belt due to an abnormal deviation. |
