JPS6451901A - Automatic box nailing machine - Google Patents

Abstract

PURPOSE: To control cylinder pressure under piston not to become negative and make it easy for the piston to completely return to the upper dead point by putting a valve near the lower dead point of the piston or at a part of gas storage chamber for return. CONSTITUTION: Loosely fit between hammering rod 6 and lower damper 11 that absorbs hammering force of piston is an annular valve 7, which has usually been pushed upward by a valve spring 10 to let the interior of cylinder 4 communicate with outer air. When piston 3 starts moving down caused by hammering, inner pressure under the piston 3 increases, the valve 7 makes close contact with valve seal surface 14, and most of gas under the piston is stored in gas storage chamber 5 for return. In the process of piston return, the valve 7 opens to take outer air through gas passages 12 and 13 immediately before the inner pressure of the cylinder is about to become negative by losing the inner pressure. Caused by the above, the inner pressure of the cylinder under the piston never becomes negative in any state.