水稻钵苗对辊式拔秧机构

针对我国水稻钵苗移栽技术对栽植机械的要求，在分析现有机型特点的基础上，提出了用于水稻钵苗拔秧的对辊式拔秧机构的设计方案，并介绍了该机构工作原理；通过拔秧机构的运动和拔秧过程分析，确定了拔秧机构工作参数的选取原则和取值范围，完成了对辊式拔秧机构的设计、试制及试验．试验结果表明，采用对辊式拔秧机构实现了水稻钵苗的自动输秧和拔秧，具有结构简单、秧苗损伤小、工作可靠等优点，为水稻钵苗有序成行栽植机械的设计奠定了基础．     

水稻钵苗行栽机试验

介绍了研制成功的水稻钵苗行栽机的构造和工作原理，以及样机的性能指标检测和生产试验．试验结果表明：该机的检测项目均达到或超过设计指标，满足水稻生产要求；采用水稻钵苗行栽机作业与人工抛秧相比具有生产效率高、秧苗分布均匀、直立度好等特点；与插秧相比具有栽植深度适宜、植伤轻、缓苗快的优点，作业质量显著提高；每公顷可增产558kg，增产幅度达到10．0％，具有明显的增产效果．水稻钵苗行栽机是目前较为理想的一种水稻移栽机械．     

A METHOD OF ANALYSIS OF MACHINE TOOL TRANSMISSION CHAIN ERROR

The indexing transmission chain error of gear cutting machines is an obviously periodic timefunction. If data are acquired properly while surveying and analyzing the error with grating typeinstrument attached to a micro-computer, the analysis will be easier and quicker. In this paper,such a system is introduced; a data acquiring interface is designed. Therefore, real-time samplingcan be performed. The results obtained from the indexing tramsmission chain error of several gearhobbing and shaping machines with this system were satisfactory.     

A COMPUTATIONAL APPROACH FOR PRESSURE DISTRIBUTION AND ROTORDYNAMIC COEFFICIENTS OF JOURNAL BEARINGS WITH COMBINED RADIAL AND MISALIGNMENT MOTIONS

A computational approach is presented to handle an enlarged linear rotordynamic model whichsimultaneously includes both radial and misalignment motions.The interactive force and momentbetween the rotating and non-rotating members are modeled using an adaptation of the classicalReynolds lubrication equation for incompressible laminar isoviscous films.First,the governingequation is derived and the method of solution is introduced based on a 2-dimension,9-point cen-tral difference.Second,force and moment components are computed by numerical integration ofthe film pressure distribution.Finally,the rotordynamic coefficients are yielded according to thegeneralized force gradients.     

A DYNAMIC ANALYSIS OF THE SPINDLE SYSTEM FOR UNIVERSAL MILLING MACHINES

In this paper,the Riccati transfer matrix method and the modal parameter identification tech-nique are applied to the dynamic analysis of the spindle system of a machine tool,the X62Wknee-type universal milling machine.With-the help of a computer,the lowest three critical speedsare calculated and these are compared with the values measured by a 7T17S analyzer,showing afairly good agreement.