考虑齿顶修缘的斜齿轮传动振动响应分析

渐开线斜齿轮进行适当修形后,可以有效地改善其啮合性能,降低噪音和延长齿轮的使用寿命。利用建立未修缘以及含不同齿廓修缘量的斜齿轮有限元模型,通过轮齿承载接触分析得到不同修缘量斜齿轮的静态传递误差和啮合刚度;在考虑齿顶修缘影响的基础上,建立了具有12个自由度的平行轴系斜齿轮转子系统动力学模型,将得到的时变啮合刚度应用于系统动力学模型中,研究不同修缘量对斜齿轮传动振动响应的影响规律。研究结果表明：在一定范围内,随着修缘量的增加,斜齿轮系统的径向振动和啮合力幅值明显降低,但当修缘量达到21 μm后其幅值有增大趋势。研究结果对确定斜齿轮的最优修形量和分析修形斜齿轮的振动特性具有重要意义。     

弹齿滚筒式捡拾器捡拾油菜试验研究

为了降低油菜分段收获作业中捡拾损失率,将弹齿滚筒式捡拾装置安装于室内土槽台车上,模拟田间作业环境设计制作了弹齿滚筒式油菜捡拾试验台,进行了台架试验和响应面分析。得到捡拾辊转速、机具前进速度和弹齿伸入留茬深度三因素对捡拾损失率影响的回归方程的数学模型;确定了三因素中按影响捡拾损失的因素显著性顺序从大到小为：捡拾装置转速、机具前进速度、弹齿伸入留茬深度。当捡拾辊转速为90 r/min,机具前进速度为0.7 m/s,弹齿伸入留茬深度为250 mm时,捡拾性能指标达到最优。     

显齿蛇葡萄种子脂肪酸GC-MS分析

目的:研究显齿蛇葡萄种子的脂肪酸含量,并与其他采收部位的脂肪酸含量进行对比.方法:以二氯甲烷为抽提剂,利用索氏提取法提取显齿蛇葡萄种子中的脂肪酸,经甲酯化处理后,采用气相色谱-质谱(GC-MS)联用技术对显齿蛇葡萄种子的脂肪酸成分进行分析和鉴定.结果:显齿蛇葡萄种核和种皮中油酸、亚油酸含量较高,棕榈酸、油酸、硬脂酸相对含量由低到高的顺序为种核、种皮、茎和叶,而亚油酸含量则正好相反.结论:显齿蛇葡萄种子中不饱和脂肪酸的含量较高,具有很好的开发利用价值.     

秦岭锐齿栎上一种新腐朽病害

报道了秦岭林区锐齿栎树上一种新的腐朽病害, 其病原菌为钩针纤孔菌Inonotus hamusetulus。根据采集的病原标本材料对该病原菌进行了详细描述,并根据野外调查对此新病害的症状和危害进行了报道。     

储粮害虫网翅鳞虫齿的形态与DNA条形码鉴定

采用形态学特征与DNA条形码相结合的方法,鉴定了采自北京市昌平区粮库准低温稻谷仓的啮虫样品.该样品的形态学特征被详细描述,且与网翅鳞虫齿的形态学描述相符.同时,其mtDNA COI作为DNA条形码被测序并分析,结果显示该样品序列与已知网翅鳞虫齿的mtDNA COI序列相似度为97.26％～99.24％;基于邻接法(NJ...     

进境原木上截获的白云杉齿小蠹及其风险分析

本文描述了从美国阿拉斯加进口原木中截获白云杉齿小蠹(Ips perturbattts Eichhoff)的形态特征、地理分布、寄主植物、生物学特性及危害等,并对其检疫重要性进行了分析.     

建兰花叶病毒和齿兰环斑病毒的检测技术及脱毒方法研究进展

为了弄清目前建兰花叶病毒(CymMV)和齿兰环斑病毒(ORSV)病毒检测和脱毒的研究概况,本研究详细阐述了2种病毒的检测方法、采用的脱毒技术和脱毒效率,分析比较了不同技术存在的弊端,指出现有的脱毒方法已不能满足兰科植物脱毒研究的需要。在此基础上,进一步提出应采用安全、可靠的新型脱毒技术来解决目前兰科植物产业瓶颈问题。超低温脱毒技术是近年来发展迅速的脱毒技术,具有独特优势,目前已在多种植物上成功应用,该方法的应用有望解决2种病毒脱毒方面存在的问题。     

不同失稳判据下边坡稳定性的规律性

以塑性区贯通、位移增量突变、计算不收敛3种边坡失稳判据为依据,采用强度折减有限元法和重度增加有限元法对简单边坡进行了分析。结果表明：以边坡潜在滑动面上某点位移增量突变作为边坡失稳判据是准确的;对于不同土体强度参数下,以位移增量关系曲线突变为判据得到的边坡的安全系数较另外两种方法稳定;对应于塑性区贯通、位移增量曲线突变和计算不收敛的3种判据,边坡潜在滑动面依次向深层发展,边坡的安全系数依次增加。     

绿色制造剃齿切削油液选择模型及应用

切削液的合理选择是提高切削加工绿色化程度的重要途径之一。根据绿色制造原理,在首先满足加工质量的前提下,建立了一种综合考虑时间、质量、成本、资源消耗和环境影响5个因素的切削液评价体系。采用油基切削液和不同类型的水基切削液进行剃齿加工对比试验,从工件质量、刀具寿命、成本和资源环境影响几个方面进行对比分析。结合试验结果,利用模糊综合评价方法对加工结果进行了评价,并据此提出了用于剃齿加工的切削液综合选择模型,通过剃齿加工实例验证了该模型的可行性。试验证明：采用水基切削液进行剃齿加工仍能满足质量要求,与传统油基切削液相比,水基能有效降低生产成本,同时减少对环境的污染。     

水平与竖向加速度-时程曲线叠加效应下边坡永久位移计算的极限上限分析

实际边坡动力稳定性受地震竖向与水平方向效应共同作用,传统边坡地震永久位移计算方法较少考虑竖向地震波影响,采用实际地震的竖向与水平方向加速度-时程曲线共同效应更符合工程实际。基于极限分析上限法和Newmark刚塑性滑块模型,提出一种基于实际水平向与竖向地震加速度-时程曲线的边坡永久位移计算改进方法,以3个工程边坡为例,探讨了两组具有代表性实测典型水平和竖向地震地面运动记录对边坡地震永久位移计算的影响。研究结果表明:不考虑竖向地震加速度时程曲线时,本文方法可蜕化为与前人方法兼容;不同地震波的竖向与水平地震动时程曲线的叠加效应不同,竖向地震对边坡永久位移的影响不可忽略。     

Worm wheel grinding method of convex pitch line non-circular gear

To overcome the precision machining difficulty of non-circular gear, a convex pitch curve of non-circular gear and worm grinding method is presented. Firstly, worm wheel is reduced to rack cutter and a rack machining convex pitch curves of non-circular gears sport model is set up. Then based on the structure of CNC worm wheel grinding machine tools and machining principle, electronic gear box of machine tools is designed and active and following axes are planned. At the mean time, the synchronous coefficient of machine tools between synchronization is deduced by machining principle of equal arc-length, and interaction models of grinding are established. At last, the worm wheel manual presetting cutter methods with non-circular gear are given and worm grinding wheel mounting angle, axial position and axial location parameter can be adjusted along the gear.     

Accurate mathematical models for relief grinding of gear hob cutters

A mathematical model for accurate relief grinding of gear hob cutters along radial directions is presented based on the analysis of grinding geometry. Both the design and manufacturing models of gear hob cutters are carefully derived and presented. By employing the plane envelope theory, the reference contour of the grinding wheel is determined in order to attain the design tool profile precisely. The tooth profile error model after regrinding is also given to confirm the grinding parameters. The model provides accurate solutions for both the tool profile and the sectional contour of the grinding wheel. It is simple and straightforward and can be used to produce high precision hob cutters systematically. Two numerical examples are presented to illustrate the effectiveness of the proposed method. The model computing results indicate that the proposed method is practical, precise and reliable. The method provides valuable reference for the design and machining of hob cutters.     

New Technology of Profile Grindng for Tow Teeth Difference Cyclodal Gear

Two teeth diffenence cyclodal gears are the key parts in cyclodal reducer. The plate abrasive wheel method which is widely used at home has very low precision and productivity. So it' s the common problem to be immediately solved. The profile grinding technology discussed in this paper has been proved by practical production to be an efficient and economical cycodal gear manufacturing method.     

The Development in Finish Machining of Hardened Gear

This article summeried the methtods in finish machining of hardened gear and mainly introduced the development of the form grinding technique in grinding wheel dressing and grinding technology. The technique, which makes use of CBN tools, of hardened gear finish machining is also briefed.     

SOME NEW MACHINING METHODS WITH THE AID OF COMPOUND MOTIONS

The paper describes a new theory and methods for designing hyperbola, degenerate circles, involute and roulette curves which have been applied in grinding convex involute gears, cutting special profiles on a gear shaper, grinding the race-way of ball thrust bearings, form grinding and grinding cyclo-cycloidal gears with an abrasive belt. All these applications have been used in industruy with considerable benefits. The curves are produced by different combinations of straight line and circle motions, Given the curve parameters of the workpieces to be machined, the best approximate curve can be obtained from a computer program designed for this purpose.     

Pitch error measurement of high-order oval bevel gear on three dimensional measuring machine

Based on the prototype workpiece which is manufactured according to the high-order oval gear envelope method,a measurement method of high-order oval bevel gear is proposed in order to verify the correctness of design and manufacture method for this gear pair. The mathematical model of measurement and evaluation is established according to the spatial gear engagement theory. Then the coordinate point set obtained from three-dimensional measuring machine is analyzed and filtered based on the actual measurement on prototype workpiece. Therefore,the ideal element is available. And then the aberration curve of pitch curve,individual circular pitch error and accumulated error can be obtained after analyzing the point set. Finally,the conclusion that the high-order oval bevel gear pitch error evaluation method is feasible can be obtained because the measurement and analysis result dovetailed basically with the theoretic calculation result.     

Rapid Manufacturing of Grinding Wheel Based on Stereo Lithography Principle

Applying a photopolymer resin instead of thermopolymer resin as a bonding material,a rapid manufacturing of grinding wheel is realized on the basis of rapid prototyping.The new grinding wheel could be enhanced by compounded with silica powder.The research shows a thin dicing blade could be solidified within tens of second or a grinding wheel within several minutes.A series of grinding and dicing experiments on silicon indicate that the photopolymer resin grinding wheel has the same ability of working precision as the thermopolymer resin grinding wheel.     

APPROXIMATION OF INVOLUTE PROFILE BY PEACH-SHAPED RING SECTION

By using the least pth min-max method, we find the best approximation of involute ptofile by peach-shaped ring section. The error of approximation is less than that of [ 1 ] and [2]. Thus we provide a new direction for dressing of a wheel for involute gear forming-grinding. In order to simplify calculation, we define the error function according to implicit equation of curve and as a result its rationalization is proved.     

Transmission model of higher-order elliptical bevel gearing and motion simulation for interference checking

Higher-order elliptical bevel gear is a typical form of the noncircular bevel gear transmission.Space spherical coordinate system of the bevel gear meshing is set up based on the meshing theory of space transmission.The varying relationship among the pitch curve,tooth profile and mesh lines are analyzed,and the equation of the gear tooth surface is developed with matrix method based on space coordinate transformation.The basic parameters of the noncircular bevel gear such as transmission ratio,modulus and the number of teeth are designed,and detailed analysis of the influence of the eccentricity on the relevant parameters is carried out as well.By using discrete numerical method and three-dimensional software,the mathematical model of the tooth profile and virtual physical model of the noncircular bevel gear are established,and then simulation on its motion and interference checking are performed.Finally,the approach for design,calculation and generation of the tooth profile is obtained and its correction has been verified by experiment.     

Tool path planning and geometry simulation for multi axis CNC belt grinding

Belt grinding machine with multi axis computer number control(CNC) system can effectively process parts with complex moulding surfaces.In this paper,iso parametric and iso planar tool path planning strategies customized for this kind of machine are proposed.The tool path generation methods are designed based on the analysis of the belt grinding process.By using least square method,optimized cross section normal is computed in the iso planar method.To improve the design efficiency of path planning,reduce experiments and increase economical benefit,the geometric simulation program based on linear grinding model is developed.Experiment on a turbine blade profile shows that the proposed algorithms work satisfyingly.