单板缺陷自动化修补技术研究进展

Research Advance in Automatic Patching Technology for Veneer Defects

单板是制造胶合板的基本单元,但存在着死节、活节、空洞、裂缝等多种缺陷,直接影响着胶合板的质量和性能。通过单板修补能去除单板缺陷,提高单板等级、质量和利用率,从而提升胶合板的质量和性能。文中介绍了单板缺陷修补工艺从“先挖后补”到“同步一体化挖补”的发展过程,阐述了2种工艺的技术原理及特点;指出后者在生产效率和挖补质量方面具有明显的优势,已得到普遍应用;着重概述了基于机器视觉的单板缺陷自动化检测技术和基于数控技术的相关自动化修补设备的研究进展和应用现状。目前单板缺陷的检测、识别、定位已逐步实现计算机化,切除缺陷、切取补片和嵌入补片已实现机械化和自动化,单板的进给已实现数控化。对以下几个方面的研究进行了展望:单板缺陷检测算法在复杂工业环境下的鲁棒性和针对不同树种单板缺陷的泛化能力,单板数控进给路径的最优规划,挖补冲头刃口角度和耐用度,以及单板挖补残料的资源化利用。

Veneer is the basic material for plywood manufacturing.There are many defects on veneer,such as dead knots,live knots,holes,cracks,etc.,all of which directly affect the quality and performance of plywood.With veneer patching,these defects can be removed,and the grade,quality and utilization rate of veneer can thus be improved,ensuring the quality and performance of plywood.The paper introduces the development and transformation of veneer patching from“patch after defect removal”to“patch at the same time of defect removal”,expounds the principle and characteristics of the two types of veneer patching and argues that the latter,which has been widely applied,enjoys obvious advantages in terms of production efficiency and patching quality.The research progress and the application state of automatic detection of veneer defects based on machine vision and related automatic patching equipment based on CNC technology are the focus in the elaboration.The detection,identification and positioning of veneer defects have been gradually computerized,the removal of defects,cutting and embedding of patches mechanized and automated,and the feed of veneers numerically controlled.Several research prospects are discussed,i.e.,the robustness of the veneer defect detection algorithm in complex industrial environments and in the generalization ability of veneer defects of different tree species,the optimal planning of the CNC veneer feed path,the cutting angle and durability of the punch,and the utilization of the residuals generated during the veneer patching.