浅谈绳索取芯钻进及其应用

绳索取芯钻进方法已经普及并已被广泛的应用于工程施工,特别是在水文工程地质勘察、地质勘探等多种采取岩心的钻进工程中,解决了工程设计中的很多难题。本文结合多年来在生产实践中的经验,论述了应用绳索取芯钻进方法的一点体会。     

关于立式绕线机拉力与单饼式线圈尺寸关系的分析

文章着重分析了立式绕线机的拉力设定与变压器单饼式线圈绕制后外型尺寸、导线线规变化情况以及线圈紧密度的关系。通过适当调整立式绕线机的拉力,从而调整线圈B端尺寸,解决现今线圈B端尺寸存在的问题。     

啤酒花摘花机构的试验研究

设计并试验了３种啤酒花摘花机构，带梳齿的两排滚筒梳刷机构，有３排梳齿的对称连杆直移梳刷机构，钢丝抽打摘花机构。针对试验中出现的问题提出了相应的解决方法，分析对比了３种摘花机构的特点。     

Design calculation and finite element simulation analysis of stranded wire helical springs

The spatial structure of single wire is analyzed based on the forming process of stranded wire helical springs. Additionally,three parameters are derived from the existing foundation,including distribution circle radius of strand,spiral parameter of single wire and track scanning parameter. The aided design method of stranded wire helical springs based on feature scanning is put forward in which the centerline model of single wire can be obtained through one scanning step and the modeling method is given based on PROE code. The simulation analysis for spring in loading is performed by using ABAQUS code based on the calculation results. The finite element analysis results show the stress-strain ability of wire and the stress distribution of the section. The affects of loading rate on vibration of coils is also found.The results can make up for the deficiency of existing methods and give more beneficial assistance for production processing and performance test of the stranded wire helical springs.     

快走丝线切割机床断丝故障分析与对策

对快走丝线切割机床断丝故障发生的原因进行了全面分析,并根据不同的断丝原因提出了相应的预防对策。     

基于DF2204无级变速拖拉机的农机无人驾驶系统研制

针对农机无人化作业需求,该研究基于DF2204无级变速拖拉机和机器人操作系统（Robot Operating System,ROS）,研发了一种适于田间作业的农机无人驾驶自主作业系统。系统由控制、规划、安全和总线通信等模块组成。对DF2204无级变速拖拉机进行硬件改造与集成,设计满足农机无人驾驶要求的控制器局域网（Controller Area Network,CAN）总线协议和ROS与CAN总线通信的消息结构,包括5类控制帧和2类状态帧;设计了基于比例-积分-微分（Proportion Integration Differentiation,PID）控制器的横向跟踪与纵向速度控制算法。在北京密云试验田开展田间小麦播种实际作业试验。试验结果表明,消息结构满足50 Hz通信负载,横向跟踪平均绝对误差为2.96 cm,纵向速度平均绝对误差0.19 m/s。研究结果可为无级变速拖拉机的无人化升级改造提供参考,提高农机智能化水平和作业效率。     

轴向射水减弱尾水管低频压力脉动试验

设计了一种从蜗壳引水通过泄水锥向尾水管内进行轴向射水的结构,实现减弱尾水管内低频压力脉动.对轴向射水和无射水情况下混流式水轮机内部压力脉动进行了模型试验研究.分析了4种部分负荷工况轴向射水和无射水时水轮机内部压力脉动幅值特性和频率特性,研究了轴向射水减弱尾水管低频压力脉动的效果.研究表明,在部分负荷工况下尾水管中存在螺旋涡带并引起尾水管壁处强烈的低频压力脉动,其频率约是1/5转频,该低频压力脉动是引起水轮机不稳定运行的主要原因;实施轴向射水后,在各部分负荷工况尾水管中低频压力脉动幅值都有明显减弱,但涡带频率基本保持不变.轴向射水使涡带向下游移动并对双涡带结构起到抑制作用.     

A comparison of the withdrawal resistance load of nails using experimental and interference approaches

Abstract

The objective of this study was to determine and predict the withdrawal resistance or pull-out load of common wire nails embedded in radial, tangential and cross-sectional grain orientation of Douglas fir (Presudotsuga menziesii) and sugar maple (Acer sacharum) samples. Four lead-hole diameters of 1.5, 2.0, 2.5 and 3.0 mm were used to create various interference fits. Nails with a diameter of 3.38 mm were driven into the samples to a depth of 10 mm for the experiments. The overall withdrawal resistance of Douglas fir samples was found to be lower than that of maple samples. Strength values of each sample increased with decreasing lead-hole diameters. No significant difference was found between withdrawal resistance values from radial and tangential sections in either species. However, significantly lower values were obtained for the cross-sections of the samples than for the two other sections. Ratios between predicted pull-out load values of the nails from both species based on the finite element numerical interference approach were very close to experimental measurements, with ratios ranging from 0.93 to 1.09. The results provide better understanding of the behaviour and performance of pull-out resistance for building systems.     

基于种子带模式小区精密播种装备的研制

摘要：为了提高小区播种的精确性和均匀性,研制了一套可适用于多种作物的基于种子带模式的精确播种装备。该套装备由种绳编织机和种绳播种机组成。种绳编织机采用气吸式排种器将种子播在种子带上并编制成种绳,排种器可通过更换带有不同尺寸和不同数量吸孔的吸种辊筒来适应多种作物的种子不同株距和不同播种量要求。种绳播种机可以实现起垄、垄定型、开沟、铺设种绳、覆土和镇压等功能。以胡萝卜为对象进行了机器播种性能试验,种绳编织机2.7%的漏播率和96.3%的株距合格率表明排种器具有很好的排种均匀性。92.3%的播深合格率以及95.7%的种子发芽率表明种绳播种机能够很好地满足农业作业要求。     

水稻精播绳制造设备的设计及大田试验

水稻种植机械化是一个尚未完全解决的难题,为此设计一种水稻直播用精播绳制造机械设备。该设备主要由送纸机构、排种机构、加捻机构和种绳卷绕成形机构等组成。在工厂内该设备将水稻种子以精确的穴距和每穴粒数卷在4~7 cm宽的纸带内并捻制成种绳,供大田播放;对该设备生产的种绳进行大田栽培试验。结果表明:该设备工作性能稳定,种绳直播水稻用种量为常规机械直播的1/2~1/3,产量超过10 t/hm2,高于对照的常规方式直播水稻约1 t/hm2。