柔化辊和光滑压辊对单板质量及旋切参数的影响

为了比较柔化辊和光滑辊对旋切单板质量的影响,对加拿大Forintek研究所的一台小型旋切机进行了改造,安装了数字控制装置并配置了两种压辊.按照L9(34)正交试验组织试验,每组变量设定值重复实验2次,共旋切了45段云杉木段.在其他参数设置相同的情况下,考查了旋刀倾角(PA)、垂直间隙(VG)和水平间隙(HG)3个变量对单板旋切质量的影响,并比较了压辊形式对单板质量的影响.结果表明:采用柔化辊旋切的单板的湿单板卷曲率比光滑压辊下降了60%,单板厚度较均匀,厚度偏差较小;柔化辊与光滑压辊的最佳旋切设置完全不同.柔化辊的最佳旋切设置为:旋刀倾角90.5°,垂直间隙9.84 mm,水平间隙2.79 mm;光滑压辊的最佳旋切设置为:旋切倾角88.5°,垂直间隙11.75 mm,水平间隙2.54 mm.

Veneer Quality and Lathe Parameter Setting Comparison Between Peeling with Incisor Bar and Smooth Roller Bar

In order to compare the effect of peeling with incisor bar and with smooth roller bar on veneer quality, a mini-lathe in Forintek's laboratory was significantly upgraded by installing digit control system and two kinds of bars. Forty-five spruce blocks were peeled with incisor bar and smooth roller bar respectively so as to investigate the effect of three controllable variables, pitch angle (PA), vertical gap (VG), and horizontal gap (HG), with three level configurations and duplication twice for each controllable peeling parameters setting, on veneer quality while other parameters were fixed. The effect of bar type on veneer curl-up and thickness variation was compared. The test results demonstrated that the peeling with incisor bar could reduce green veneer curl-up ratio over 60% compared with the smooth roller bar, and generate more even veneer thickness and less veneer thickness variation than the smooth roller bar. The optimum lathe settings for incisor bar and for smooth roller bar were quite different, which indicate that the lathe settings have to be adjusted after changing bar from one to another. The optimum lathe settings for incisor bar were PA 90.5°, VG 9.84 mm,and HG 2.79 mm. In contrast, the optimum lathe settings for smooth roller bar were PA 88.5°, VG 11.75 mm,and HG 2.54 mm in this experiment.