基于DSP芯片的斜齿轮插齿数控加工技术研究

国内斜齿轮加工一般采用滚齿机或者进口插齿机,由于产品体积过大和机床价格昂贵而受到限制.文章对采用DSP芯片的数控插齿加工技术进行了研究,提出了虚拟轴插补技术以及用软件实现电子齿轮差动技术,利用DSP芯片的高速处理能力进行跟踪插补,经初步试验证明该方法理论上可行,实际中可以运用.     

几种常用的二指平动抓手的结构和特点

机械手在工业生产中应用广泛,抓手是机械手抓取物体的执行机构.文章介绍了常用的楔式结构和双气缸结构的二指平动抓手,分析了这二类抓手的性能特点,阐述了选择抓手时要考虑的问题.     

Hardness and fracture toughness of moissanite

Disparities prevail among the reported hardness and fracture toughness values for hard and brittle materials. A better understanding of the physical nature of hardness and fracture toughness and a standardized technique for reliable measurements of these quantities is urgently needed. We strongly recommend the use of the measured hardness after the bend in the hardness versus load (H−F_Load) curve, when the hardness approaches its asymptotic value. The present work reports a systematic study of hardness and fracture toughness on moissanite (single crystal hexagonal silicon carbide, 6H-SiC) samples. The measurements were performed over a broad load range from 0.49 to 294 N with the direct indentation method. Asymptotic values of Knoop hardness of H_K = 19 GPa and Vickers hardness of H_V = 22 GPa were reached at a high load between 50 N and 100 N. A consistent fracture toughness of K_IC = 1.8 MPa·m^1/2 was obtained across the entire load range. Our study presents experimental results for the hardness and fracture toughness of moissanite in the asymptotic-hardness region, and it raises concern regarding the application of moissanite single crystals as anvil material under shear/fracture conditions.     

Catalytic behavior of potassium containing compounds for diesel soot combustion

Alkali doped oxides were synthesized and tested as catalysts for diesel soot combustion using a combinatorial method. It has been found that potassium shows better promotion of the catalytic activity than other alkali elements, and most of the potassium-rich oxides showed similar catalytic behaviors when catalysts and soot were mixed in a slurry. The influence of different mixing methods, including loose contact, tight contact and slurry (wet) mixing with different soot suspensions, on the catalytic behavior of some transition metal oxides, alkali metal carbonates and potassium-containing oxides were studied through thermogravimetry and XRD. The high activity of potassium-containing catalysts is found to be due to the intimate contact between soot and potassium cations caused by polar solvents. Potassium containing catalysts degraded after repeated thermal cycles due to the loss of potassium. It was also found that the addition of transition elements can inhibit the loss of potassium.     

一种基于TL494芯片的电动车电机控制器

他励直流电动机驱动系统结构简单、性能可靠、成本低,适合在小型电动车上运行,有效的降低了电动汽车的价格,有利于电动汽车的普及。本文在分析电动车用他励直流电机工作原理的基础上,论述电机驱动系统的整体方案,并设计3KW/36V他励有刷直流电机控制器。该控制器主要通过TL494控制,包括36V铅酸蓄电池欠压保护,控制器的过热保护等功能。经实验证实该控制器达到设计指标,工作稳定可靠,满足电动车的各种运行情况,保护功能完善并具有能量回馈等功能。     

Estimation of Vehicle Speed Based on Wheel Speeds from ASR System in Four-Wheel Drive Vehicles

Three major methods currently in the use of determining vehicle speed based on wheel speeds,the minimum wheel speed,minimum wheel speed corrected by slope method and the Kalman filter method,are analyzed,with merits and defects of each approach stated. Through simulations,the Kalman filter method based on minimum wheel speed shows improved accuracy,in addition to better adaptivity to vehicle reference speed. It also can be used to acceleration ship regulation (ASR) in part-time four-wheel drive vehicles.     

基于过程知识的设计过程重用

为提高产品设计过程的效率,从＂产品设计过程亦是产品＂的观点出发,提出了基于设计过程知识的设计过程重用方法,设计了基于过程知识的设计过程重用的流程;给出了过程重用系统的模块组成及其结构.并以某重型汽车变速箱设计过程为实例,实证了该方法与流程能有效地提高变速箱设计过程的效率,进而缩短了变速箱的上市周期,提高了变速箱的质量.     

电控柴油机分缸均衡控制算法及试验

柴油机各个气缸的进气量、喷油量、燃烧等存在差异,导致气缸间存在做功差异,直接影响柴油机转速的平稳性以及排放性能等。针对位置式电控柴油机,采用PI闭环控制,通过瞬时转速信号识别并计算各缸的工作差异,利用分缸均衡控制算法对油量进行补偿修正。试验结果显示低转速稳态工况转速波动由7 r/min降至3 r/min,各缸工作不均匀度由±5 r/min降至±2 r/min,在瞬态过程和高转速3 400 r/min时该算法仍然适用有效。     

边界元法在汽车室内噪声建模中的应用

为探讨汽车室内噪声建模的方法,应用边界元法描述汽车车身室内的噪声水平。首先基于Hypermesh有限元软件建立汽车车室空腔有限元模型,然后以NASTRAN的格式导入到SYSNOISE环境中构建单区域边界元计算模型。引进车内座椅吸音材料对室内声场的影响,重新构建包含座椅的汽车室内多区域边界元计算模型。通过在车身室内安置一个点声源进行激励,分别采用单一和多区域边界元法模拟车身室内声场响应,获得在频率0~1 000 Hz范围内车身室内声场的频响函数。经试验验证,通过对比分析可知多区域边界元法计算结论与试验结果较好吻合,这表明多区域法比单区域法具有更高的精度。     

基于NX的摩托车车身曲面逆向设计

以摩托车车身曲面逆向设计为背景,从点云数据处理、复杂曲面重构以及曲面质量检测三方面,探讨了NX在逆向工程中的应用.研究表明,NX强大的点云处理功能、高级曲面设计及检测功能使得逆向设计变的更为方便,并在保证产品质量的前提下,大大缩短产品的开发周期.