チップソーの摩耗経過 : 単一鋸歯によるパーティクルボードの断続切削

Abstract

チップソーから切り取った単一の鋸歯で, パーティクルボードを積層した直方体状のブロックを断続切削し, その際の超硬チップの摩耗状態, 刃先の摩耗量, 切削力を調べた。刃先は切削初期に急激に摩耗し, その後は緩やかに摩耗を続けたが, 逃げ面側での摩耗がすくい面側に比較して大きく, 逃げ面側に広い摩耗帯が形成された。摩耗面の状態は逃げ面, 刃先線近傍, すくい面で異なっていることが観察された。切削力の3分力は, 切削距離と共に次第に大きくなったが, 切削初期の増加が顕著であった。特に背分力は最も広範囲に変化したが, これと逃げ面摩耗帯幅の間には相関が見出された。摩耗量や摩耗状態に関する本実験の結果は, 実際にチップソーを用いた場合と大差なく, 本切削方法によってもチップソーの摩耗実験を行ない得る見通しを得た。

In order to examine the wearing process of tungsten carbide saw tips, a laminated experimental block of particleboard was interruptedly turned with a single saw tooth, which was cut out of a tungsten carbide tipped circular saw (Figs. 1 and 2). At several cutting lengths the wear of the tool was observed using a metallographic and a scanning electron microscope, and the three cutting force components (Fig. 2) were also measured. The cutting edge retracted very rapidly at the beginning and then continued to retract more slowly. The clearance (back) face of the tool wore more than the rake (front) face as the edge wear proceeded, and a wide wear land was formed on the clearance face (Figs. 3, 4 and 8). Scanning electron micrographs showed that the extreme worn edge had a smoother appearance than the other wear surface; and that striations and grooves developed in the cutting direction on the back wear land while a few shallow depressions were often formed on the rake face (Figs. 5, 6 and 7). The values of the three cutting force components increased with the cutting length. In particular, the perpendicular component (F2) started at a relatively low value and increased very rapidly at the beginning (Fig. 9). This force, F2, was found to have a constant relationship with the width of back wear land, Wb (Fig. 10). The wearing process of the carbide saw tip used in this study was almost the same as the results when a carbide tipped circular saw had been actually used, so that the present cutting method could simulate a cicular sawing, to some extent, concerning the wear phenomena.