| 摘要 |
Circular saws (Fig 1), band saws (Fig. 2) or frame saws (Fig. 3) are intended for sawing straight as well as curved timber with knots and other irregularities which tend to direct the saw blade so that the kerf deviates from the desired kerf. It is known to design saw blades as a pack of at least two blades close to each other (1, 2). According to the invention the two saw blades are driven with intentionally variable relative speeds, each of them having their row of teeth (3, 4) which cannot interfere with the other row. Deviations from a wanted kerf are indicated by means of the deflections of the saw blade pack when it goes through the object to be sawn. The deviation controls the relative speeds of the saw blade halves. The saw blade which at a certain moment goes faster cuts a void towards which the pack is forced by the pressure from the teeth of the other saw blade. The method can be used on one hand to guide the saw to produce a straight kerf, on the other hand to guide the saw manually, and further to guide the saw according to a program for example to obtain planks with constant thickness from curved logs and also for joineries. It is also possible to produce chips with long fibres cheaper for fibreboard production. |
