On Satisfaction of the Fifth Necessary Condition of Proper Part Surface Generation in Design of Plunge Shaving Cutter for Finishing of Precision Involute Gears

2006 ◽  
Vol 129 (9) ◽  
pp. 969-980 ◽  
Author(s):  
Stephen P. Radzevich

In this paper, a novel modified scheme and effective computer representation for design of a plunge shaving cutter is presented. The paper aims to develop a novel design of shaving cutter for plunge shaving of precision involute gears. The study is carried out on the premise of satisfaction of the fifth necessary condition of proper part surface generation (PSG) when designing the plunge shaving cutter. In the current study, the author’s earlier developed DG/K method of surface generation is used together with the principal elements of analytical mechanics of gears. (The DG/K method is based on fundamental results obtained in differential geometry of surfaces, and on kinematics of multi-parametric motion of a rigid body in the E3 space. The interested reader may wish to go for details to the monograph: Radzevich, S.P., Fundamentals of Surface Generation, Monograph, Kiev, Rastan, 2001, 592 pp., and to: Radzevich, S.P., Sculptured Surface Machining on Multi-Axis NC Machine, Monograph, Kiev, Vishcha Schola, 1991, 192 pp.) In the particular case under consideration, the method employs (a) an analytical description of the gear tooth surface to be machined, (b) configuration of the plunge shaving cutter relative to the involute gear, (c) analytical representation of the coordinate systems transformations, and (d) the fifth condition of proper PSG that is adapted to finishing of precision involute gears. The fifth condition of proper PSG is investigated in the paper. On the premise of the obtained results of the investigation, a novel design of plunge shaving cutter for finishing of precision involute gears is proposed. The developed novel design of plunge shaving cutter can be used on shaving machines available on the market, e.g. on Gleason’s new Genesis™ 130SV computer numerical control (CNC) shaving machine.

2006 ◽  
Vol 129 (3) ◽  
pp. 334-345 ◽  
Author(s):  
Stephen P. Radzevich

This paper aims at development of a novel design of precision gear hob for machining involute gear on a conventional gear-hobbing machine. The reported research is based on use of fundamental results obtained in analytical mechanics of gearing. For solving the problem, both the descriptive-geometry-based (DGB) methods together with pure analytical methods have been employed. The use of DGB methods is insightful for solving most of the principal problems, which consequently were analytically solved. The analytical methods used provide an example of application of the DG∕K-method of surface generation developed earlier by the author. For interpretation of the results of research, several computer codes in the commercial software MathCAD∕Scientific were composed. Ultimately, a method of computation of parameters of design of a hob with straight-line lateral cutting edges for machining of precision involute gears is developed in the paper. Coincidence of the straight-line lateral cutting edges of the hob with the straight-line characteristics of it generating surface eliminates the major source of deviations of the hobbed involute gears. The relationships between major principal design parameters that affect the gear hob performance are investigated with the use of vector algebra, matrix calculus, and elements of differential geometry. Gear hobs of the proposed design yield elimination of the principal and major source of deviation of the desired hob tooth profile from the actual hob tooth profile. The reported results of this research are ready to put in practice.


Author(s):  
J Hedlund ◽  
A Lehtovaara

Gear analysis is typically performed using calculation based on gear standards. Standards provide a good basis in gear geometry calculation for involute gears, but these are unsatisfactory for handling geometry deviations such as tooth flank modifications. The efficient utilization of finite-element calculation also requires the geometry generation to be parameterized. A parameterized numerical approach was developed to create discrete helical gear geometry and contact line by simulating the gear manufacturing, i.e. the hobbing process. This method is based on coordinate transformations and a wide set of numerical calculation points and their synchronization, which permits deviations from common involute geometry. As an example, the model is applied to protuberance tool profile and grinding with tip relief. A fairly low number of calculation points are needed to create tooth flank profiles where error is <1 μm.


Author(s):  
Alessio Artoni ◽  
Massimo Guiggiani

The teeth of ordinary spur and helical gears are generated by a (virtual) rack provided with planar generating surfaces. The resulting tooth surface shapes are a circle-involute cylinder in the case of spur gears, and a circle-involute helicoid for helical gears. Advantages associated with involute geometry are well known: in particular, the motion transmission function is insensitive to center distance variations, and contact lines (or points, when a corrective surface mismatch is applied) evolve along a fixed plane of action, thereby reducing vibrations and noise emission. As a result, involute gears are easier to manufacture and assemble than non-involute gears, and silent to operate. A peculiarity of their generation process is that the motion of the generating planar surface, seen from the fixed space, is a rectilinear translation (while the gear blank is rotated about a fixed axis): the component of such translation that is orthogonal to the generating plane is the one that ultimately dictates the shape of the generated, envelope surface. Starting from this basic fact, we set out to investigate this type of generation-by-envelope process and to profitably use it to explore new potential design layouts. In particular, with some similarity to the basic principles underlying conical involute (or Beveloid) gears, but within a broader scope, we propose a generalization of these concepts to the case of involute surfaces for motion transmission between skew axes (and intersecting axes as a special case). Analytical derivations demonstrate the theoretical possibility of involute profiles transmitting motion between skew axes through line contact and, perihaps more importantly, they lead to apparently novel geometric designs featuring insensitivity of transmission ratio to all misalignments within relatively large limits. The theoretical developments are confirmed by various numerical examples.


Author(s):  
K. Y. Yoon ◽  
S. S. Rao

Abstract A new method is proposed for reducing vibration and noise of involute gears. The method is based on the use of cubic spline curves for gear tooth profile modification. The tooth profile is constrained to assume an involute shape during the loaded operation. Thus the new gear profile assures conjugate motion at all points along the line of action. The new profile is found to result in a more uniform static transmission error compared to standard involute profile thereby contributing to the improvement of vibration and noise characteristics of the gear.


2005 ◽  
Vol 128 (4) ◽  
pp. 803-811 ◽  
Author(s):  
Stephen P. Radzevich

In this paper a novel modified scheme and effective computer representation for hobbing operation of precision involute gears is presented. The specific goals of the paper are as follows: (a) to provide a comprehensive understanding of the principal features of addendum modification of an involute gear hob tooth, (b) to come up with a novel approach for the computation of parameters of modification of the hob tooth addendum, (c) to determine the applicability and advantages of the application of the developed approach. The key concept in this paper is satisfaction of the necessary conditions of proper part surface generation (Radzevich, S. P., 2002, Computer Aided Design, 34, pp. 727–740) in gear hobbing operation. The research is performed with the application of the novel DG∕K approach of surface machining earlier developed by the author. The DG∕K approach of surface generation is based on fundamental results obtained in differential geometry of surfaces, and in kinematics of multiparametric motion of a rigid body in E3 space. The interested reader may wish to go to the monographs (Radzevich, S. P., 2001, Monograph Kiev, Rastan; 1991, Monograph, Kiev, Vishcha Shkola Publishing) for details. Both of the monographs are available from The Library of Congress. A novel approach for the computation of constraints on the actual values of addendum modification of an involute hob is reported in this paper. The advantages of the developed approach are threefold. It yields the computation: (a) of the minimum and the maximum allowed value of the normal pressure angle; (b) of the maximum allowed value of addendum modification of an involute hob, and (c) of the maximum allowed reduction of addendum of a gear hob. In the way of implementation is also described.


2006 ◽  
Vol 129 (1) ◽  
pp. 31-37 ◽  
Author(s):  
Qi Fan

Modeling of tooth surface generation and simulation of contact is an important part of computerized design and manufacturing of spiral bevel and hypoid gears. This paper presents new developments in this subject. Specifically, the paper covers: (i) development of a generic model of tooth surface generation for spiral bevel and hypoid gears produced by face-milling and face-hobbing processes conducted on free-form computer numerical control (CNC) hypoid gear generators which are incorporated with the Universal Motions Concept (UMC); (ii) a modified algorithm of tooth contact simulation with reduced number of equations of the nonlinear iterations and stabilized iteration convergence; and (iii) an algorithm of numerical determination of contact lines that form the contact patterns. The enhanced approach of contact simulation can be generally applied to other forms of gearings. Two examples, a face-hobbing design and a face-milling design, are illustrated to verify the implementation of the developed algorithms.


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