| 摘要 |
<p>Frame saw for sawing of essentially horizontally fed timber comprising a plurality of spaced apart saw blades placed substantially perpendicular to the direction of feed of the timber, i.e. without overhand. A crankshaft is connected to a sash in which the said saw blades are clamped to impart to the sash a reciprocating upward and downward motion with upper and lower turning points in relation to and controlled by a system of guides which by the said crankshaft via one or several guide connecting rods and via one or several controlled guide links is arranged to be moved or phase-displaced in the direction of feed of the timber before the sash is moved. The guide system and the guide connecting rods are designed with fulcrums in or in relation to the said guide links, which are pivotably disposed. The fulcrums of the guide system are so located in relation to the fulcrums of the guide connecting rod that the fulcrums of the guide system move along a circular arc with a shorter radius than do the fulcrums of the guide connecting rod. This arrangement imparts to the guide system and thus to the saw blades a movement with such a horizontal component as to cause the guide system to be displaced against the feed direction of the timber when the sash and thus the saw blades are in the vicinity of the said upper turning point and during the downward movement, and in such a complementary horizontal movement in the feed direction of the timber when the sash and thus the saw blades are in the vicinity of the said lower turning point and on their way up. Thus, the cutting engagement of the saw blades with the timber becommes more or less constant during the greater part of the cutting period.</p> |
