棉秆重组方材的机械加工性能

Machining properties of reconstituted square lumber made from cotton stalk

棉秆重组方材是一种新型人造生物质材料,它是棉秆材料化利用的一个新方向,其制备过程主要包括棉秆的疏解、干燥、施胶、组坯、四面加压以及后期处理。为了探明棉秆重组方材机械加工性能,为其高附加值加工利用提供技术依据,该研究参照美国材料与试验协会标准ASTM D1666-87和新西兰林业科学研究院制定的评价标准,分别对其刨削、砂光、铣削成型、钻孔、榫眼加工、车削及横截等7种机械加工性能进行测试和综合评价,并对各项机械加工缺陷进行分类,参照中国林业行业标准LY/T 2054-2012对棉秆重组方材进行综合评分。结果表明:棉秆重组方材的砂光、钻孔和铣削成型3项加工性能的质量等级均为优秀,其质量等级值分别为4.37、4.43和4.37。刨削、榫眼加工和车削的质量等级为良好,质量等级值分别为3.47、3.87和3.07。横截性能表现中等,质量等级值是2.63;在满分50分的机械加工性能综合评分中,棉秆重组方材得分为39.5;当刨削厚度一定时,每英寸刀痕数对刨削质量有较大影响,当每英寸刀痕数由25增加到48时,棉秆重组方材刨削性能明显提高。砂光处理可明显改善刨削加工后的缺陷,也是棉秆重组方材刨削后必要的加工工序;棉秆重组方材在机械加工过程中出现的主要缺陷有削片沟痕、毛刺沟痕、毛刺和撕裂等,在实际产品加工应用时,需充分考虑其加工特性,选择合理加工方式和参数,以期提高加工质量和效率。该研究结果有助于充分认识和开发棉秆重组方材的利用潜能,对优化棉秆重组方材性能、提高其加工利用水平具有重要意义。

Reconstituted square lumber made from cotton stalk is a new type of man-made composite material and has a promising future, which is a new direction of material utilization of cotton stalk. Its preparation process mainly includes cotton stalk combing, drying, glue blending, lay-up, pressing in four surfaces, and after-treatment. In order to find out and comprehensively evaluate the machining properties of reconstituted square lumber made from cotton stalk, and provide technical evidences for its high value-added utilization, seven mechanical processing items which contain planing, sanding, shaping, boring, mortising, turning, and cross cutting were studied in this paper. Tests on planing, sanding, shaping, boring, mortising, and turning were based on the standard of American society for testing and materials（ASTM D1666-87）, and the test on cross cutting was referred to the method established by the New Zealand Forest Research Institute. Various machining defects were classified on the basis of a series of experimental results. The comprehensive evaluation score of the machining properties of reconstituted square lumber made from cotton stalk was conducted according to the Chinese forestry-industrial standard（LY/T 2054-2012）. The results showed that quality grades of machining properties of reconstituted square lumber made from cotton stalk were excellent in the items of sanding, boring and shaping. According to the weighted integration method, the quality grade values of the three items were 4.37, 4.43, and 4.37, respectively. The quality grades of the machining properties of planing, mortising, and turning were good. The quality grade values of planing, mortising, and turning were 3.47, 3.84, and 3.07, respectively. The quality grade of the machining property of cross cutting was poorer than others, which was in the middle grade and the quality grade value was 2.63. Reconstituted square lumber made from cotton stalk scored a 39.5 out of 50 in the comprehensive evaluation score of machining properties. When the machining thickness of planing was 1.6mm and constant, knife marks per inch had a significant impact on quality. When knife marks per inch increased from 25 to 48, the planing machining property of reconstituted square lumber made from cotton stalk had a significant improvement. Sanding did significantly improve the processing defects of planing. Sanding was the necessary process of reconstituted square lumber made from cotton stalk after planing. During the machining processing, the main defects in planing were chipped grain and torn grain. The main defects in sanding were surface fuzzy and fuzzy grain. Shaping defects were mainly fuzzy grain and torn grain. The main defects in mortising, cross cutting, boring, and turning were fuzzy grain and torn fiber in varying degrees. In order to improve the processing quality and efficiency, we should take into full account the machining properties and select a reasonable processing methods and parameters when reconstituted square lumber made from cotton stalk is in processing and application. The study results are beneficial to fully recognize and exploit the application potential of reconstituted square lumber made from cotton stalk. The results also have significance for optimizing the properties of reconstituted square lumber made from cotton stalk and improving its processing and utilizing levels.