Influence of Setting Error of Tool on Tooth Profile and Contact Point of Face Gear Drive

In order to analyze the influence of setting error of tool on both tooth profile and contact characteristic of orthogonal face gear drive,the coordinate systems with and without setting error are established.Moreover,the equations of tooth profile and contact points of face gear drive are derived by envelope principle.According to the equations,the change of tooth profile and the contact points position on face gear are analyzed.The tooth surface and contact points are obtained by numerical simulation.Results show that the tooth profile and contact characteristic of face gear drive are not sensitive to the setting error of tool.

Generation Principle of Helix Tooth Profile in Hypocycloid Pinw heel Transmission and Its Contact Characteristics

The transmission characteristics of gear drive can be improved with the use of novel tooth profiles.A theoretical study on tooth profile of the hypocycloid pinwheel transmission and contact analysis of gear pair based on finite element method(FEM) are carried out,respectively.The line contact between mated tooth surfaces becomes point contact according to a plus movement.Through loaded tooth contact analysis(LTCA),the contact stress and load distributions for the proposed hypocycloid pinwheel transmission and the traditional one are discussed.The analysis results show that the developed tooth surfaces have anticipatory point contact characteristics under loads and contact fatigue dangerous area locates around the ultimate contact position.

Geometrical design of variable ratio tooth profile based on Boolean subtraction operation and a novel modification method

Variable transmission ratio racks show great potential in rice transplanters as a key component of variable transmission ratio steering to balance steering portability and sensitivity.The objective of this study was to develop a novel geometrical design method to achieve quick,high-quality modeling of the free curvilinear tooth profile of a variable transmission ratio rack.First,a discrete envelope motion 3D model was established between the pinion-sector and the variable transmission ratio rack blank based on the mapping relationship between the rotation angle of the pinion-sector and the displacement of the rack,according to the variable transmission ratio function.Based on the loop Boolean subtraction operation,which removed the pinion-sector from the rack blank during all moments of the discrete motion process,the final complex changing tooth shape of the variable transmission ratio rack was enveloped.Then,since Boolean cutting residues made the variable ratio tooth surface fluctuant and eventually affected the precision of the model,this study proposed a modification method for establishing a smooth and continuous tooth profile.First,a novel fitting algorithm used approximate variable ratio tooth profile points extracted from the Boolean cutting marks and generated a series of variable ratio tooth profiles by utilizing B-spline with different orders.Next,based on a transmission stability simulation,the variable ratio tooth profile with optimal dynamic performance was selected as the final design.Finally,tests contrasting the transmission stability of the machining samples of the initial variable ratio tooth profile and the final variable ratio tooth profile were conducted.The results indicated that the final variable ratio tooth profile is more effective than the initial variable ratio tooth profile.Therefore,the proposed variable ratio tooth profile modeling and modification method for eliminating Boolean cutting residues and improving surface accuracy is proved to be feasible.

Design of Linear Functional Noncircular Gear with High Contact Ratio Used in Continuously Variable Transmission

Continuously variable transmission(CVT)of noncircular gear has the technical advantages of large bearing capacity and high transmission efficiency.The key technology of CVT with noncircular gear has been broken through some countries,and is in the stage of deep application research.Although the characteristics and design methods of noncircular gear pairs have been continuously studied in China,the noncircular gear CVT is still in the preliminary exploration and research stage.The linear functional noncircular gear pair,whose transmission ratio is a linear function in the working section,to realize continuously variable transmission was the research object in this paper.According to the required transmission ratio in the working section,the transmission ratio function in the non-working section was constructed by using a polynomial.And then the influence of pitch curve parameters in the working section on which in the non-working section was also analyzed to obtain the pitch curve suitable for transmission of this gear pair.In addition,for improving the stability and bearing capacity of gear transmission,the noncircular gear pair transmission with high contact ratio was designed.Furthermore,the accurate value of the contact tooth length was calculated based on the gear principle and the characteristics of the involute tooth profile,from this the contact tooth length error was calculated by comparing the accurate value with its actual value obtained by the rolling experiment.Finally,an indirect method to verify the contact ratio by detecting the contact length error of the tooth profile was proposed.

Non-undercutting condition and parameter optimization for cycloid ball planetary transmission

The transmission performance of cycloid ball planetary transmission(CBPT) is affected by cycloid tooth undercutting directly, and the design of CBPT can be optimized by the non-undercutting condition. Firstly, the theoretical equation of cycloid tooth is given, and the curvature radius of cycloid tooth profile is derived. Secondly, according to the relationship between the curvature radius and the distribution circle of balls, the non-undercutting condition of cycloid tooth profile is established, and the non-undercutting critical condition is deduced. Finally, the validity of the non-undercutting critical condition is verified by simulation. The result shows that the non-undercutting critical condition can be used to optimize the design of CBPT.

Modeling and experiment of grinding wheel axial profiles based on gear hobs

Hobbing is one of the crucial gear manufacturing processes with high precision and high efficiency.In order to improve the accuracy of hobbing and hob relief grinding,more precise grinding wheels are demanded for relief grinding in the production of gear hobs.In this paper,a new and accurate mathematical method for calculating the axial profile of grinding wheel based on the corresponding gear hob to be ground is proposed.Considering that most researches have been conducted to focus on the optimization of hob geometric feature and only can be applied to a specific type of hand of helix and rake angle of gear hobs.The method in this paper can be served as a general algorithm for generating axial profile of grinding wheels on the basis of the spatial envelope theory,the principle of coordinate system transformation,and studies on normal profile of single-tooth.The accuracy of grinding hobs is based on applying the approach in practical manufacturing.Taking two typical different kinds of pre-grinding gear hobs as examples for calculation and experiment,the results of tooth profile errors strengthen the position that the validity and feasibility of this method,it can be employed for gear hob design and grinding processing.

Method for generating non-circular gear with addendum modification and its application in transplanting mechanism

With a focus on the design of tooth profiles of non-circular gears with addendum modifications that conform to the given complex transmission ratio curves and based on a series of discrete point sets on the pitch curves,the criteria for tooth profile distortion and undercut in non-circular gears were proposed.With the constraint of no tooth profile distortion and undercut,the addendum modification coefficient was introduced into the calculation of the distorted and undercut segments of the tooth profile of a non-circular gear,and the addendum modification coefficient of each contact point of the non-circular gear was obtained.Based on the generating principle for gear shaping with gear cutters,a theoretical model for calculating the tooth profile of non-circular gears with addendum modification was derived.The cutting and radial feeding motions of the pinion cutter were ignored,and only the meshing motion was considered.The involute tooth profiles of the pinion cutter enveloped the tooth profile of the non-circular gear.3D automatic non-circular gear model generation software was developed,which was a secondary development product of the software UG.A non-circular gear in a rice potted seedling transplanting mechanism was designed,and the transplanter was developed and tested.The test results showed that the designed tooth profile of non-circular gear achieved the variable transmission ratios required by the transplanting mechanism.When the transplanting efficiencies were 140 plants/min,160 plants/min and 180 plants/min,the transplanter completed the rice potted seedling transplanting operation with high quality.