Reverse Design and Test of Non-circular Gear & Crank-Rocker & Gear Trains Weft Insertion Mechanism

For the purpose of obtaining satisfactory performance of the non-circular gear & crank-rocker & gear trains (NCCRG) weft insertion mechanism which was proposed in this paper, the ideal kinematic curve of this weft insertion mechanism was given, and the reverse solution models of this mechanism were established. A reverse design and simulation software was compiled based on Visual Basic 6.0 to obtain the mechanism parameters, including the pitch curves and tooth profiles of the non-circular gears. A test-bed of this mechanism was developed according to these parameters. The kinematic performance of this weft insertion mechanism was tested by high-speed video tape recorder with its corresponding video analytical software Blaster's MAS. And the test results were identical with the theoretical calculation. Compared with the conjugate cam weft insertion mechanism which is applied on TT96 rapier loom, under the condition of same weft insertion rate, the variation of acceleration of this mechanism is smaller. This novel weft insertion mechanism can meet the requirements of weft insertion on rapier looms with smooth and steady motion.

Investigation into precision engineering design and development of the next-generation brake discs using Al/SiC metal matrix composites

Substantially lightweight brake discs with high wear resistance are highly desirable in the automotive industry.This paper presents an investigation of the precision-engineering design and development of automotive brake discs using nonhomogeneous Al/SiC metal-matrixcomposite materials.The design and development are based on modeling and analysis following stringent precision-engineering principles,i.e.,brake-disc systems that operate repeatably and stably over time as enabled by precision-engineering design.The design and development are further supported by tribological experimental testing and finite-element simulations.The results show the industrial feasibility of the innovative design approach and the application merits of using advanced metal-matrix-composite materials for next-generation automotive and electric vehicles.

Reverse design and tests of vegetable plug seedling pick-up mechanism of planetary gear train with non-circular gears

In the previous research,the seedling pick-up mechanism of the planetary gear train with incomplete eccentric circular gear and non-circular gears for vegetable plug seedlings still has two shortcomings.One is that not enough seedling pick-up depth leads to a low success ratio of seedling pick-up at high rotation speeds,the other is that the smaller seedling pushing angle results in poor seedling pushing effect.Therefore,the reverse design of the seedling pick-up mechanism based on its motion trajectory was carried out.The local trajectory of seedling pick-up and seedling pushing sections was adjusted to obtain the theoretical motion trajectory of the seedling pick-up mechanism.The cubic non-uniform B-spline curve was used to fit the adjusted trajectory.A novel seedling pick-up mechanism of the planetary gear train with non-circular gears was proposed,including three combined non-circular gears,four non-circular gears,one planetary carrier,and two seedling pick-up arms.The reverse design model of the mechanism was established.The analysis and design software of the mechanism was developed to obtain the mechanism parameters meeting design requirements.The virtual prototype of the mechanism was established and its physical prototype was manufactured.Through the virtual motion simulation and high-speed photographic kinematics bench tests of the mechanism,the kinematic model and results of reverse design of the mechanism were verified,with the kinematic performances of the mechanism prototype studied.The seedling pick-up tests of the mechanism were conducted in the laboratory.The success ratios of seedling pick-up were 94.2%,95.6% and 90.2% while the seedling pick-up efficiencies of the mechanism were 60,80 and 100 plants per minute per row,respectively.Besides,the seedling pushing effect was improved mush because of the greater seedling pushing angle.The seedling pick-up mechanism through revise design is of high value to be applied in the practical vegetable plug seedling transplanters.

A New Type of Waveguide Distribution for the Accelerator Module Test Facility of the European XFEL

The European XFEL, which has been constructed at DESY in Hamburg, Germany, is an X-ray-Free Electron Laser, which provides X-ray light of unprecedented properties for different experiments in physics, chemistry, biology and technology [1]. The XFEL is based on superconducting cavity technology, which is required to accelerate an electron beam up to 17.5 GeV. The facility is installed about 20 m underground in a 3.4 km long tunnel of 5.2 m diameter. High power RF systems are required to accelerate the beam to the required energy. Each RF station provides RF power to 4 accelerator modules with 8 superconducting cavities by a waveguide RF distribution system [2, 3]. Besides electrical and RF properties, mechanical properties are of high importance, since the waveguide distribution system and its components have to be manufactured, assembled and aligned with high precision. In order to test 100 superconducting accelerator modules within two years three test benches have been created in the AMTF （accelerator module test facility） to achieve the rate of one superconducting module per week. Each RF station of the test facility consists ofa 5 MW RF station at 1.3 GHz, 1.37 ms pulse width and 10 Hz repetition rate, with a waveguide distribution system. Each waveguide distribution supplies RF power to eight cavities, four times a pair of cavities. The distribution allows for a maximum power of 1 MW per cavity when the distribution is switched to a mode supplying power to only four cavities. A new type of 1 MW isolator and a new compact 5 MW power divider have been developed to achieve that goal. We present the waveguide distribution for this test stand and describe the performance of the different elements.

新型钢管混凝土梁柱节点力学性能试验研究

为研究内加强环式圆钢管混凝土柱与矩形钢管混凝土梁这种新型连接节点的力学性能,设计了缩尺钢管混凝土梁柱节点试件,开展了相同梁柱节点试件的静力加载试验和低周往复加载试验。通过研究该节点试件的破坏模式、荷载-位移曲线以及拟静力加载试验的骨架曲线、核心区剪切变形等,分析了节点试件的承载能力、延性和耗能能力,全面考察了同一梁柱节点在静力加载和低周往复加载两种工况下的受力性能和破坏模式。结果表明:钢管混凝土梁柱节点试件核心区强度较强,破坏模式主要为梁端破坏,低周往复加载试验时试件梁柱连接处附近的梁端钢板发生拉裂破坏和钢板鼓曲,静力加载试验时试件梁端焊缝发生拉裂破坏;试件延性较好,加载过程中经历了弹性、弹塑性和塑性发展阶段。最后提出了该类钢管混凝土梁柱节点核心区的抗剪强度计算公式。

4行气吸式马铃薯原原种精量播种机设计

马铃薯原原种的繁育最早由人工种植,其生产成本高,不利于规模化生产。基于原原种的种植农艺要求、种子物理性状和耕作种床条件等情况,进行了4行气吸式马铃薯原原种精量播种机的研究设计。通过台架和田间试验得到,该播种机的操作性能、播种精度和质量都满足种植的农艺要求,实现了马铃薯原原种机械化精量播种作业。

气辅成型工艺参数正交精准设计优化

“双碳”目标下,气辅成型技术为塑料成型实现降低碳排放提供了有效途径。为精准规划气辅成型参数,提升气辅成型质量和效率,有效降低碳排放,采用三维数值模拟和成型实验,研究参数交互作用下气辅成型工艺正交优化。结果表明,参数交互作用对气体穿透长度影响小,而对气指缺陷的影响显著。极差分析的基础上,获得了优选参数组:熔体温度240℃,注气压力3 MPa,延迟时间4 s,模具温度40℃。经数值模拟和成型实验验证,优选参数组下得到气辅塑件的气体穿透长度及气指指标优良,可用于气辅成型实际生产。

基于性能化设计的RC框架结构破坏机制试验研究

为验证广东省标准DBJ/T 15-92—2021《高层建筑混凝土结构技术规程》“二水准、二阶段”抗震性能化设计方法的合理性、可靠性和容错性,设计两批相同的3榀抗震构造等级分别为一级、二级、三级的1∶4缩尺平面RC框架结构试件,加载时各层楼板上布置铁质配重模拟分布荷载,考虑楼板及楼板荷载对框架结构破坏机制的影响。试验采用位移控制单点加载,加载点位于三层楼面梁标高处,在柱纵向钢筋达到屈服应变前为单循环加载,屈服后采用三循环加载。通过拟静力试验,考察结构的抗震破坏形态和破坏机制,分析滞回曲线、延性、刚度、耗能等抗震性能指标的演化规律。试验结果表明:试件损伤破坏的塑性铰发展路径基本相同,符合梁端塑性铰延性机构的破坏机制;试件没有明显剪切破坏特征,承载力利用系数ξ能实现“强剪弱弯”抗震设计要求;6榀框架结构试件的滞回曲线饱满,抗震延性系数范围为4.36~6.10,等效粘滞阻尼系数最大值范围为0.125~0.165,展现了良好的抗震耗能性能;楼板提高框架梁的刚度和承载力,对试件抗震破坏机制有明显影响,试件保持了“强柱弱梁”抗震破坏特征,构件重要性系数η能保证“强柱弱梁”的抗震设计要求;试件破坏特征有随机性,但破坏机制整体规律性较强,不同抗震构造等级试件的梯度特征明显。

“机械精度设计”课程思政教学研究与实践

根据“机械精度设计”课程的教学特点,分别从课程思政探索的思路与目标、设计与实施、特色与创新、反思与分析四个模块出发,探讨课程思政融入的方式方法以及努力的方向。基于知识—能力—人格“三位一体”的人才培养模式,在课程教学中把马克思主义立场观点方法的教育与科学精神的培养结合起来,注重强化学生工程伦理教育,培养学生精益求精的大国工匠精神,激发学生科技报国的家国情怀和使命担当,丰富了铸牢中华民族共同体意识的形式。

星载高精度偏振扫描仪热控设计与验证

偏振扫描仪安装于卫星对地板,周围有其他载荷的遮挡,热环境复杂,是卫星热控设计的难点。文章根据扫描仪不同部组件的控温要求设计热控方案,包括:主光学组件与框架隔热并包覆多层隔热组件;红外探测器热沉、头部电路盒分别设计独立的散热路径,通过外贴热管连接辅助散热板散热;结合电加热主动控温;在主要部位安装隔热垫。该热控方案已通过热平衡试验在地面的考核验证,在轨遥测数据显示:主光学组件温度控制在(16±1)℃,头部电路盒温度控制在6~8℃,红外探测器热沉温度控制在(-22±1)℃,满足扫描仪各项温度指标要求。以上表明该热控方案合理有效,对同类型光学载荷的热控设计及优化具有借鉴意义。

基于AIGC的智能绘图机器人高精度路径规划与实验研究

随着人工智能技术的不断发展,人工智能生成内容(AIGC)在各个领域展现出巨大潜力。文章从高精度路径规划角度出发,设计并实现了一种基于人工智能生成内容技术的高精度智能绘图机器人系统。通过引入生成对抗网络(GAN)、路径规划算法(A*算法)以及多种高性能传感器,该系统能够在复杂多变的环境中进行高精度、高速度的绘图操作。实验结果表明,所设计的智能绘图机器人在路径规划、绘图精度和传感器性能方面表现优异,特别是在动态环境中的实时响应能力和极端条件下的稳定性表现突出。

特高压直流输电系统可控自恢复消能装置用慢速机械开关研制

慢速机械开关是特高压直流输电系统可控自恢复消能装置中重要的开关设备,在装置中起到控制和保护用,其必须具备短时间快速合闸、可靠开断避雷器残余直流持续电流的能力。介绍了慢速机械开关的方案设计、核心部件设计和校核以及型式试验,最终研制成功了慢速机械开关。

基于CFD茶叶烘干机的优化设计与试验

针对目前6CH型自动链板式茶叶烘干机存在结构设计欠合理、温度分布不均匀性等问题,对6CH型自动链板式茶叶烘干机进行优化设计与试验。将导流板的布置进行优化设计,对优化后的茶叶烘干机采用计算流体力学软件CFD建立干燥机部件的稳态温度场仿真模型,通过截面温度、速度云图,分析得到3组工况下(进风速度20 m·s^(-1)温度130℃、进风速度25 m·s^(-1)温度140℃、进风速度30 m·s^(-1)温度150℃),干燥室内部均能满足所需高温环境,并且能满足物料快速烘干再掉落至下一层的要求。采用三因素三水平正交试验,确定实际工况下的最优参数组合,试验结果表明,当进风温度为144.81℃、鼓风机风速为20.62 m·s^(-1)、输送速度为1.78 m·s^(-1),基于此组合下的降水幅度为40.75%,碎茶率为2.07%,均满足且超过农艺要求,该研究为茶叶烘干与烘干机关键参数优化提供参考。

精密铸铝件一体化设计及在车身轻量化中的应用

铝合金一体化精密铸造技术是实现汽车轻量化的重要方式之一。本文首先采用轻质铝合金材料、熔模真空吸铸工艺以及拓扑优化对白车身前副车架及仪表板横梁进行“材料-工艺-结构”一体化设计;其次对比一体化铝合金结构件的质量、研发成本、研制周期,较原钢制件大幅度降低;最后对加装一体化精密铸铝件的白车身进行刚度与模态的有限元仿真分析及台架试验。结果表明,一体化设计后,前副车架及仪表板横梁分别轻量36.6%、30.8%,同时白车身性能均满足设计要求。

丘陵山地桑叶采收机取袋机构优化设计与试验

针对丘陵山地桑叶采收机收集装置自动取袋过程实现困难的问题,通过桑叶取袋装袋过程运动学分析,对取袋机构进行了优化设计与试验.首先通过分析整机结构与取袋机构工作原理,建立了取袋机构运动学分析模型;以最大横向取袋距离和取袋瞬间角度为目标,建立了优化设计模型,并开发了辅助分析设计软件,确定了取袋机构参数的取值范围;采用带基因策略的非支配排序遗传算法(NSGA-II)对模型求解,获得最优设计参数.其次根据最优设计参数建立了三维模型,利用ANSYS进行运动学仿真分析,结果表明取袋机构末端执行器位移图像和速度曲线与设计要求一致,可满足取袋机构设计要求.最后研制出桑叶采收机与取袋机构样机,对取袋机构样机开展高速摄像试验,验证了取袋机构运动轨迹与理论仿真结果基本一致.以曲柄转速、吨口袋种类、磁吸石外圆尺寸为试验因素,取袋开袋成功率为指标开展桑叶取袋开袋正交试验,并根据最优组合进行验证试验.试验结果表明:曲柄转速为0.1 r/s、吨口袋形状与尺寸为方体550 mm、磁吸石外圆尺寸为20 mm时,取袋开袋成功率为97.50%,表明该机构能完成取袋作业,可实现桑叶采收机的取袋开袋功能.

超声滚挤压执行器的机床精密调高装置研究

为解决超声滚挤压装置在超声加工时,由于执行刀具在机床垂直高度方向上,挤压头总是无法与工件中心轴线处于同一水平线,导致加工准备工作耗时长、高度调节难的问题,文章提出一种既能满足超声滚挤压执行器高度调节而且使用时不受机床局限的精密调高装置的机械设计方法。利用蜗轮蜗杆机构,实现高度方向调节,同时由楔块承重,可以承受在刀架夹紧情况下的巨大载荷,保护内部零件、螺母和弹簧片稳固构件,确保该装置在作业时避免出现移动,增加稳定性。最后通过试验对比得出:利用该装置后滚压头的调高时间缩短到30 s以内,测得工件粗糙度降低了7%左右,直径偏差降低了50%~67%。满足超声加工时在不同工况下,对刀具高度调节实现精准把控,极大程度地解决了超声滚挤压执行器在不同机床工作时高度调节的需求。

数字化技术在机械制造中的应用

随着数字化技术的不断发展,传统的机械制造方式正在迎来革命性的变革,计算机辅助设计(CAD)、计算机辅助制造(CAM)、计算机辅助工程(CAE)等为机械制造行业带来了巨大的变革,推动了制造业向智能、高效、可持续的方向发展。该文以机械制造过程中的数字化生产线、精密制造技术及数字化机床仿真技术为案例,深入探讨了数字化技术在机械制造中的应用,重点分析数字化生产线的建设及精密制造技术在数字化时代的发展趋势,最后聚焦于数字化机床仿真技术的研究。数字化技术为精密制造提供了更精准的工艺控制和质量监测手段,通过数字化仿真,制造企业可以在实际生产之前对机床性能进行精准评估,提高了设备的利用率和产品质量,为制造过程的优化提供了有力支持。

压缩机机壳用低温高强韧铸钢材料研究

通过对材料合金成分及热处理工艺参数进行的实验室研究,确定了压缩机机壳低温高强韧钢材料的内控成分及热处理工艺参数,经造型、熔炼、浇注、清理、热处理、精整后,制造出符合用户图纸、技术要求的铸件。

66kV湿式轻型海缆特殊试验研究

为了模拟66kV湿式轻型海底电缆在全寿命周期中可能承受的压溃、拉伸、弯曲、冲击、扭转等多种机械载荷,根据机械载荷类型的不同搭建了不同的试验平台,针对压溃载荷,利用摩擦试验平台模拟海底电缆的短期受压情况,利用重物长期堆叠模拟海底电缆的长期受压情况;利用疲劳试验机、弯曲刚度试验机搭建拉伸弯曲试验平台,模拟还原海底电缆运行过程中承受的拉伸、弯曲载荷;利用冲击试验机模拟海底电缆在实际过程中承受的冲击载荷;搭建扭转试验平台,利用角度传感器、力传感器测量海底电缆承受的扭转载荷。通过对66kV湿式轻型海底电缆进行以上特殊机械试验,对试验数据进行相应的分析从而得到电缆允许的压溃载荷、侧压力、抗冲击能力、刚度、允许扭转角度等工程相关信息,为海底电缆的生产、导缆、运输、敷设、施工作业以及后期运维提供试验数据的支持。

Design and experiment of a Chinese chive harvester

Recognizing the labor intensity of current domestic Chinese chive harvesting and the need for its mechanized harvesting,a self-propelled electric Chinese chive harvester is designed.The machine is composed of a control system,supporting mechanism,cutting parts,conveying and clamping mechanisms,frame,and collection system.It can complete Chinese chive feeding,cutting,transmission,and binning operations at one time.It has a cutting width of 0.25 m and wheelbases of 260 mm and 460 mm.Two 12 V,42 Ah lead-acid batteries were used in series as the power supply.The mechanical properties of Chinese chive were analyzed,and shear and compression tests were carried out to determine that the average value of the maximum shear force on the chives is 129 N.Up to a compressive force of 225 N,Chinese chives are not damaged.According to the physical characteristics of Chinese chives and the requirements of the harvesting operations,design and calculation of the key components of the harvester’s transmission mechanism and the strength of the whole machine frame were completed.An embedded control system and Cortex-M3 microprocessor were used to control the harvester and realize its functions of rolling and harvesting while regulating its speed and protecting its motor.Using the Box-Behnken test design method,the machine’s operating speed,cutter speed,and cutter height were selected as influencing factors,and the lodging rate and loss rate were evaluated as a test.A mathematical regression model of influencing factors and evaluation indexes was established to analyze the influence of these factors and indexes and optimize test parameters.The optimal parameter combination is determined to be:operating speed,1.1 km/h;cutter speed,220 r/min;cutter height 2.0 cm.The parameters were verified from field tests and the results showed that under the optimized parameter combination,the average lodging rate was 3.96% and the average loss rate was 3.23%,indicating that the Chinese chive harvester meets the agronomic requirements of Chinese chive harvesting.This harvester could be modified to harvest other crops such as chrysanthemums and Mongolian Chinese chive.