圆锯安全罩升降自动控制

圆锯上安装安全罩是行之有效的安全防护措施。长文着重介绍了如何利用单位控制电路的原理,实现多位控制。从而达到安全罩自动升降,实现安全生产的目的。     

基于预测控制的连续平压机热压板升降系统同步控制

【目的】针对连续平压机热压板升降系统被控对象多且具有非线性、强耦合性等特点,提出基于广义预测控制的环形耦合同步控制方法,以降低热压板升降系统在上升和下降过程中各路液压缸的同步运动误差,确保热压板在升降过程中保持在同一水平面上,减小因不同步对热压板及相关元器件的损害。【方法】建立热压板升降系统同步控制模型,采用广义预测控制算法对每路液压缸的控制量进行优化,构建包含同步误差影响的热压板升降系统优化性能指标函数,导出各子系统基于预测控制的环形耦合同步控制规律。为降低计算复杂性,将优化函数进行分解,在各路液压缸的优化控制性能指标中引入该液压缸和相邻一侧液压缸同步误差的影响,对控制参数在线滚动优化,抑制扰动和随机噪声,采用环形耦合方式对各路液压缸进行同步控制。在系统控制模型基础上进行Matlab仿真试验,并与基于PID的主从控制方式进行对比,分析2种控制方式的位置跟踪、同步误差和抗扰动能力。【结果】环形耦合同步控制方法可保证单路液压缸的跟踪精度,使相邻液压缸之间的同步跟踪误差趋于零,能够实现各路液压缸之间的同步控制,解决某路液压缸受扰动时无法与其他液压缸精确同步的问题。Matlab仿真试验结果表明,与常规主从控制方法相比,基于预测控制的环形耦合同步控制方法具有更好的位置跟踪精度、同步性能、抗扰动能力和响应速度,对于升降过程中的系统扰动和参数突变,系统能迅速恢复稳定,体现出算法的鲁棒性和适应性。【结论】环形耦合同步控制方法更适用于被控对象多的系统,且系统的复杂程度不随被控对象增多而增加,预测控制算法与环形耦合同步控制的结合可实现连续平压机热压板升降系统中对液压缸较高的位置跟踪和同步控制精度,有利于减小因液压缸不同步造成的对设备的损害。     

一种微型林间作业机械升降系统的设计

介绍了一种微型林间作业机械升降系统的设计.该升降系统采用液压装置使平台实现升降运动,其结构形式简单,升降平稳,操作方便,体积小,质量轻,是一种理想的林间作业机械.     

ArcGIS在林业有害生物飞防设计中的应用

以武冈市2018年第一代马尾松毛虫直升机防治为例,详细阐述了利用ArcGIS软件对第一代马尾松毛虫发生区进行飞机防治规划设计的方法和步骤,同时结合GPS的精确定位、飞行控制以及历史航迹等评估防治效果的方法,可进一步提高飞机防治在林业有害生物防治应用中的精度和效率。     

断层扫描技术在木材无损检测中的应用

为实现木材缺陷的自动、高效检测,提高木材利用率,应用自主研发的CT设备扫描原木木段横切面,并重建其二维图像和三切面视图。结果表明:通过二维图像可观察横切面年轮、节子和裂纹等信息;结合三视图和透视图可精确定位缺陷位置。为无损检测木材内部结构特征,及木材分等提供依据。     

组合式木工机械

组合式木工机械一种具有脚踏升降垂直钻孔功能的组合式木工机械。其平压刨、锯磨机和垂直钻孔机构可以组合拼装在机架上。垂直钻孔机构是以立柱和套筒为主结构，用脚踏升降装置控制其升降，并以变距传动装置驱动钻头总成。本实用新型与现有技术相比较，具有结构简单，组合...     

新型直线电机驱动式地铁受电弓

介绍了新型直线电机驱动式地铁受电弓的技术参数、结构、工作原理及设计特点。该新型地铁受电弓采用升弓弹簧装置升弓,直线电机驱动克服升弓弹簧力矩实现降弓,采用蓄电池供电方式,无需供风风源。电机集成了升降弓限位模块,当受电弓完全升弓到位时和降弓到位时,电机都能停转,保证了受电弓正常升降弓。     

中密度纤维板铺装成型技术与装备研究进展

铺装成型是中密度纤维板工业化生产的重要工序。针对中密度纤维板工业化铺装成型的机械结构与质量控制,分析纤维计量仓、机械式铺装头、均平与扫平装置、成型皮带、铺装质量控制、连续预压致密与预压高度同步升降控制、速度同步性控制等方面的技术特点和现存问题,提出工业化铺装成型技术进一步的研究方向,为中密度纤维板铺装成型技术研究和创新设计提供参考。     

变频调速调节器

变频调速调节器ＷＶＤＴ系列变频调速调节器是控制电弧炉炼钢中机电传动式电极自动升降的电气设备。主要由电气控制柜、电机和减速器组成。与普遍采用的调压调速调节器比较，该调速器的技术特点是：保留了目前调压调速技术的阻抗控制、解耦控制、双重双模控制等优点；完善...     

一种基于Wi-Fi的井下人员精确定位算法研究

简单分析了基于RFID的人员定位技术、基于到达时间差TDOA的定位技术以及基于接受信号强度RSSI的定位技术。在此基础上针对煤矿井下巷道的特殊环境,提出了一种基于两点定位的井下人员精确定位算法。通过实地模拟实验得出该算法的定位误差基本控制在2~3 m之内。     

磨削参数对木材砂带磨削能耗的影响

磨削加工是木质材料加工中非常重要的环节,直接影响产品加工精度和表面质量。目前关于木材磨削加工的理论研究不足,磨削工艺参数和动力配置不合理,导致磨削加工能耗较高。采用5因素5水平正交试验,考察了磨削深度(T_s)、砂带磨料粒度(G)、砂带速度(V)和进给速度(U) 4个磨削参数,以及磨削方向与木材纹理的夹角(λ)对砂带磨削杨木和红松时的空转功率(P_i)、有功功率(P_a)、磨削功率(P_s)、磨削力做功功率(P_sf)及功率利用率(μ)的影响。采用BP(back propagation)神经网络系统建立木质材料砂带磨削P_sf和μ的仿真模型,最后用功率利用率的直观分析法对磨削工艺参数进行优化。结果表明:磨削参数对Psf的影响顺序为U>T_s>V>G,且都为高度显著影响因素;对μ的影响顺序为T_s>G>V>U,T_s为高度显著影响因素,G和V为显著影响因素。最佳功率利用率(高磨削效率)的磨削方案为:磨削深度0.1 mm,砂带速度10.74 m/s,进给速度5.16 m/min,磨料粒度60目,杨木横纹磨削,红松斜纹磨削。平均功率利用率45%,最大功率利用率78%,最小功率利用率21%。     

木门异形表面砂光粗糙度分析

选取水曲柳、黑胡桃、樱桃木三种常用树种的薄木贴面木门为试验对象,分别对素门、涂饰1道底漆和2道底漆后的木门进行砂光,检测各道砂光工序后木门的表面粗糙度,并分析其变化规律,为木门机械化异形砂光提供量化评价数据,生产企业砂光工艺的优化和质量控制提供参考。     

人造板砂光工序的降耗措施

影响人造板砂光工序成本的主要因素有:砂带类型、砂粒粒度、砂光机选型、进料速度及管理方法等。本文结合生产实际情况,提出了降低人造板砂光成本的措施.结果表明,成本下降幅度可达65.1％.     

实木门表面砂光机工作头的研究与设计

为了提高实木门的砂光效率和质量,根据我国实木门的结构特点,设计一款专门用于砂光实木门表面的砂光机。本文主要对实木门表面砂光机工作头进行了研究与设计,并对各部件的功能及整体结构进行介绍。该设计对国内门面砂光机功能的进一步改善具有一定的指导作用。     

Evaluation of two surfacing methods on black spruce wood in relation to gluing performance

Surface quality and gluing performance of black spruce samples prepared by peripheral straight-edge knife planing and sanding were studied. Four wavelengths (1.5, 1.9, 3.1, and 6.5 mm) and four rake angles (15°, 20°, 25°, and 30°) were tested for peripheral planing. Three feed speeds (4, 10.5, and 17 m/min) and three grit size sandpapers (80, 100, and 120) were studied for sanding. The resulting surfaces were glued with an isocyanate adhesive and tested to evaluate their gluing performance (shear strength and percent wood failure). Results revealed that planing with a rake angle of 20° and wavelengths of up to 3.1 mm produced wood surfaces with adequate glueline shear strength. Sanding with 80-grit sandpaper produced the best glueline shear strength, regardless of feed speed. After accelerated aging, the loss of gluing performance was lower for the sanded samples compared with that of planed samples. In general, sanding process produced better wood surfaces for bonding with the adhesive studied.     

Effects of abrasive mineral, grit size and feed speed on the quality of sanded surfaces of sugar maple wood

Sanding is a common practice required in order to prepare wood surfaces for coating. Little literature is available regarding the effect of sanding parameters on the quality of surfaces. Sugar maple wood surfaces were evaluated in samples that had been sanded using two types of abrasive minerals, three grit sizes and four feed speeds. Roughness, wetting properties and cell damage were used to assess surface quality. Both abrasives decreased roughness and cell damage from 100- to 120-grit sanding stage. Addition of a 150-grit stage did not further reduce the roughness, whereas the cell damage continued to decrease. Increasing feed speed led to rougher surfaces due to higher fibrillation. Surfaces produced by silicon carbide were smoother and less damaged than those obtained with aluminum oxide. However, the surfaces sanded with aluminum oxide were more wettable and showed no significant difference in wetting time as a function of grit size. For these surfaces, the wetting time was reduced as feed speed increased.An erratum to this article is available at .An erratum to this article can be found at     

Microstructural study of sanded and polished wood by replication

Replicas of sanded and polished specimens of wood, mainly of pine and spruce, have been made to study microstructure and the development of drying cracks. Three surfaces, the radial surface, the tangential surface and the cross section, have been studied. Replication has also been carried out on knots, finger joints and complex surfaces where dimensional changes occur. It has been shown that sanding and polishing is a useful means of exposing microstructure of wood. The exposed microstructure can be successfully transferred to a replica to be investigated by light optical or environmental scanning electron microscopes. Microstructural characteristics, drying cracks, knots, finger joints and complex geometry have been observed and analysed. Problems associated with sanding and replication are discussed.This work was carried out in the Department of Wood Technology and Processing, Royal Institute of Technology (KTH). Financial support from KTH is gratefully acknowledged.     

酚醛树脂密实化杨木的机械加工性能研究

以水溶性低分子量酚醛树脂处理人工林杨木板材,参考ASTM标准,并结合国内实木地板的生产工艺,对处理前后板材的横截、刨切、榫槽加工和砂光性能进行评价.结果表明:经过处理后,杨木板材的各项加工性能均得到明显改善,加工缺陷明显减少,表面光洁度和平整度明显好于未处理材,适合用于制造实木地板.     

Method for evaluating the influence of wood machining conditions on the objective characterization and subjective perception of a finished surface

A method for evaluating the influence of the operating parameters of wood machining (planing, sanding) on the quality of a finished surface was established. The influence of each of the operations involved was studied using different strategies. For the planing operation, three levels were established (Level 1, 2 and 3) by determining different values for each of the major process parameters (tool rotation speed, feed speed, depth of cut). For both, surface preparation and polishing, two levels were established with a fixed setup. Finally, as finishing products, two different transparent coatings were selected (water-borne and solvent-borne). The quantitative evaluation of the state of the surface was assessed by means of an artificial vision system for the determination of the pseudo-roughness of wood surfaces. A filtering method based on fast Fourier transforms was applied and it was possible to derive three criteria for evaluating the resulting profile.     

Wettability and adherence of acrylic paints on long and short rotation teaks

ABSTRACT

The quality of finished wood products depends on the quality of its coating layer. An important indicator for evaluating the quality is Adherence of the paint on the wood surface. The purpose of this research was to analyze the effect of wood surface roughness and the viscosity of acrylic paints (pure acrylic and acrylic copolymer) to the wettability and Adherence for long and short rotation teaks. Wood surface with various degrees of roughness was prepared by sanding with abrasive papers of P120, P240, and P360 grits. Different viscosity of the acrylic paints was prepared composition between paint and water (w/w) of 100:0, 90:10, 80:20, and 70:30. The wettability of the acrylic paints on teak wood surfaces was measured using a sessile drop contact angle method with the S/G model. Adherence of the coating layer was measured using a crosscut test. The results showed that the increase in the roughness (Ra) and the decrease in the viscosity of the paints resulted in the increase in the wettability which leads to better Adherence of acrylic paints on the surface of teak woods. The pure acrylic paint generated better wettability and Adherence compared to the acrylic copolymer.