| 摘要 |
PROBLEM TO BE SOLVED: To eliminate problems such as generation of unpleasant noise or injury to a panel cover by providing a damper means for decelerating and controlling rotation of the panel cover for opening and closing a space in an upper portion of a machine frame when a locking means is released and the panel cover is biased from a closing position to an opening position by a spring force. SOLUTION: In a structure for blocking a space in an upper portion of a machine frame 12 by a freely opening and closing panel cover 22, the panel cover 22 is rotatably supported by means of bearing a shaft 24, which is fixed to one side of the panel cover 22, to a blanket. A coil spring 50 for biasing the panel cover 22 towards an opening direction is wound on the shaft 24. Further, a base end of an arm 40 is fixed to one end of the shaft 24, and a pinion 44 is rotatably mounted to a protrusion 42 formed at a tip portion of the arm 40. Then, the pinion 44 is engaged with an circular arc rack 46 greased with a viscous material, thus forming a damping means for decelerating and controlling the rotation in the opening direction of the panel cover 22 by the coil spring 50.
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