Oil Film Stiffness of Double Involute Gears Based on Thermal EHL Theory

Lubrication failure is one of the main failure forms of gear failure.Time varying meshing stiffness is an important factor affecting the dynamic behavior of gears.However,the influence of oil film stiffness is usually ignored in the research process.In this paper,according to the meshing characteristics of double involute gears,based on the non-Newtonian thermal EHL theory,a new calculation method of normal and tangential oil film stiffness for double involute gears is established by the idea of subsection method.The oil film stiffness difference between double involute gears and common involute gears is analyzed,and the influence of tooth waist order parameters,working conditions,and thermal effect on the oil film stiffness are studied.The results reveal that there are some differences between normal and tangential oil film stiffness between double involute gears and common involute gears,but there is little difference.Compared with the torque,rotation speed and initial viscosity of the lubricating oil,the tooth waist order parameters have less influence on the oil film stiffness.Thermal effect has a certain influence on normal and tangential oil film stiffness,which indicates that the influence of thermal effect on the oil film can not be ignored.This research proposes a calculation method of normal and tangential oil film stiffness suitable for double involute gears,which provides a theoretical basis for improving the stability of the transmission.

EFFECT OF GEAR WIDTH AND HELIX ANGLE ON FACTOR OF DYNAMIC LOAD OF DOUBLE CIRCULAR ARC HELICAL GEARING

Based on theory of mechanical dynamics, meshing characteristic as well as thedynamic model of double circular arc helical gearing, an analysis approach and a computer programhave been developed for studying the state of dynamic load and factor of dynamic load of thegearing, the changing situation of dynamic load and dynamic load factor vs some affecting factorssuch as gear width, helix angle and accuracy grade etc are investigated. A series of conclusions areobtained: ①With the increasing in the values of gear width, the dynamic load factor appears slowdecreasing tendency in most region of gear width. ②When the accuracy grades of the gearing areimproved, the values of dynamic load factor decrease. ③The value of dynamic load factor appears adecreasing tendency with the increasing of value of helix angle at the same ratio of criticalrotational speed.

THEORETICAL INVESTIGATION ON STATE OF LOAD DISTRIBUTION AMONG CONTACT BEARINGS OF DOUBLE CIRCULAR ARC HELICAL GEARS

A dynamic analysis approcach to investigate the state of load distribution among contact bearings of double circular are belical gears is proposed and a computer program is developed for calculating the factor of iced distribution based on the theory of W-N gears. The changing situations of load distribution among contact bearings of the gears influenced by main issues are analyzed by a series of parametric studies.

Research on Design Method of Non-Circular Gear Pair with Double Generating Angles

In order to enhance the bearing capacity of non-circular gear pair, the non-circular gear pair with double generating angles is proposed based on the design idea of unsymmetrical gear with double pressure angles. The tooth profile is designed by generating cutting theory, the pure rolling mathematic model that the center line of unsymmetrical rack roll along non-circular pitch curve is built, the digital model of non-circular gear with double generating angles is created through the second development method of CAD software, and then the drive characteristic and tooth strength are analyzed. The results show that the design method for double generating angles non-circular gear proposed in this paper is feasible, which is significant to improve the bearing capacity of non-circular gear pair.

EXPERIMENTAL STUDY ON LUBRICATION BEHAVIOR OF DOUBLE ENVELOPING HOUK GLASSWOKM GEARING

The lubrication behavior of double enveloping hourglass worm gearing is studied experimently. The effects of rotational speed of the worm and load on the formation of the fluid film between engagement tooth surfaces are investigated in detail. and working angle of this worm gearing is also analyzed. Some beneficial results are obtained。

Design and experiment of double planet carrier planetary gear flower transplanting mechanism

At present,there is a lack of miniaturized and highly reliable plug seedling transplanting mechanism in flowerpots planting operation,in order to meet the needs of large displacement and high vertical uprightness for flower transplanting,the paper combined the transmission characteristics of the non-circular gear planetary gear train with the swing flexibility of the cam gear and proposed a double planet carrier planetary gear transplanting mechanism.The linkage of the mechanism performs variable speed rotation relative to the first planet carrier,the linkage serves as the second planet carrier,and the transplanting arm performs variable speed swing relative to the linkage.A mathematical model of a single planetary carrier mechanism was first established using the method of open linkage group solution domain synthesis,then established the kinematic equations of the second planet carrier and the transplanting arm.The two parts are combined to form the mathematical solution model of the proposed mechanism.The initial trajectory was planned according to the trajectory requirements of seedlings planting operation,the non-circular gear pitch curve in the first planet carrier was obtained and the length of the first planet carrier is 120 mm.Then using the key points’angular deviation between the initial trajectory and the improved trajectory to obtain the cam parameters which driving the transplant arm,consequently determined the length of the second planet carrier is 69.25 mm and the length of the transplant arm is 112.4 mm.Finally,the prototype of the mechanism was manufactured,and the test verified the correctness of the design method of the double planet carrier planetary gear flower potting transplanting mechanism.The transplanting success rate of this mechanism reached 94.43%,and the plug seedlings planted in flowerpots had high uprightness.This research can provide a reference for the automatic development of research on flower transplanting machines.