Now showing 1 - 10 of 20
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    New approach for evaluating form errors of engineering surfaces
    (01-01-1987)
    Manufactured features generally deviate in size, form and relations with respect to other features from the features desired by the designer. Designers specify certain limits for these deviations that depend on functional requirements. The specification of different form errors is dealt with by the International Organization for Standardization (ISO). ISO also specifies that an ideal geometric feature must be established from the actual measurements such that the maximum deviation between it and the actual feature concerned is the least possible value. In practice, the least squares (LS) method is sometimes used for establishing the ideal feature, as this method is based on sound mathematical principles. However, the least squares procedure does not yield a minimum value. Therefore some attempts have been made to arrive at a form error based on the minimum deviation (MD) principles. A stray peak or valley on the actual feature introduces considerable variation in the results obtained by the minimum deviation method. This paper suggests a new approach based on the minimum average deviation (MAD). In this method, the ideal feature is established by using a search technique for different geometric features such as straight lines, circles, planes, cylinders and spheres. Using simple numerical examples, the values obtained by this approach are compared with the values obtained by the least squares and minimum deviation methods. © 1987.
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    Minimisation of error on the effective profile of pinion type gear shaping cutters
    (01-01-1988)
    Sankaranarayanasamy, K.
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    Gear shaping cutters are provided with top-relief and rake angles to facilitate effective cutting. Due to this, the profile representing the cutting edge (effective profile) is altered. This paper outlines a method of obtaining the effective profile and its deviations from the theoretical involute form required. This paper also deals with a method that modifies the pressure angle, while maintaining zero deviation at the reference circle, so that the effective profile closer to the theoretical form is obtained after grinding the rake face. The Golden section optimization method is used to get the optimum value of the modified pressure angle. The effect of regrinding on the profile error of the cutting edge is also brought out. The method suggested in this paper will be useful to the designers and manufacturers of gear shaping cutters. © 1988, All rights reserved.
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    Minimum achievable quality of involute gears in generation processes
    (01-01-1988)
    Sankaranarayanasamy, K.
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    In gear generation processes, the involute profile of the gear is obtained as an envelope of the successive cuts made by the flank of the generating tool. The irregularities of the profile thus generated limit the quality of the gear. This paper reports the minimum achievable quality based on the maximum theoretical height of the irregularity for the involute spur gears. © 1988, All rights reserved.
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    Limiting conditions in gear shaping for corrected involute gears
    (01-01-1983)
    Srinivasan, N.
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    The technique most commonly used to produce cylindrical gears, both external and internal, is gear shaping with a pinion-type cutter which generates gear flanks with rotating motion and removes chips by reciprocating action. Though the gear shaping cutter of a specific module can be used to cut gears with a wide range of teeth of the same module, in practice the inherent errors limit the number of teeth that can be cut on the gear. This paper analyses such inherent errors for both external and internal gears, taking into account the effect of a tip-relief angle and considering both "corrected" and "uncorrected" gear forms. © 1983.
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    Profile deviations in internal gear shaping
    (01-01-1982)
    During the shaping process, the profile generated on the internal gear deviates from the theoretical profile even when the difference between the number of teeth on the gear and the cutter is large. This paper describes a method for simulating the shaping process while cutting the internal gear. For the first time, quantitative evaluation of profile deviation has been made possible by this approach. The results are adequately verified by experiments. A thorough analysis has been carried out on the simulated profiles and suggestions are made to reduce the deviation from the theoretical profile. © 1982.
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    Optimizing workpiece position in centreless grinding by roundness profile analysis
    (01-01-1987)
    Subramanya Udupa, N. G.
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    Radhakrishnan, V.
    Selection of optimum setting in centreless grinding is based on the roundness error obtained. However, the roundness profile can be characterized in many ways, including mean line average height and harmonic analysis. In this paper, an approach based on a detailed analysis of the roundness profile is suggested. Theoretical and experimental results are presented. © 1987.
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    Assessment of errors in geometrical relationships
    (01-12-1988)
    For functional reasons, the relationships between geometrical features of engineering components must be specified and controlled during manufacture, as must their geometrical form. This paper describes the concepts involved in the measurement and evaluation of geometrical relationships and explains the application of the least-squares technique with simple numerical examples. © 1988.
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    PROCESS MONITORING IN CENTRELESS GRINDING FOR OUT-OF-ROUNDNESS AND SURFACE FINISH CRITERIA.
    (01-12-1986)
    Udupa, N. G.Subramanya
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    Radhakrishnan, V.
    Selection of optimum conditions in centreless grinding is based on the roundness error and surface finish which are post-process measurements. In-process measurement of the roundness error and surface finish, because of its complexity, has hardly been attempted in centreless grinding. But monitoring of some of the process parameters during grinding can be done to control the quality of the ground parts. In this paper, the influence of some of the process parameters on the quality of the ground parts is brought out and how monitoring of these parameters can lead to the optimum conditions is discussed. Experimental work carried out in this connection is reported.
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    WORKPIECE MOVEMENT IN CENTERLESS GRINDING AND ITS INFLUENCE ON QUALITY OF THE GROUND PART.
    (01-01-1988)
    Subramanya Udupa, N. G.
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    Radhakrishnan, V.
    The grinding action and the rounding mechanism are highly complex in centerless grinding. The process geometry and the dynamic stability of the workpiece are critical factors affecting the quality of the ground parts. The workpiece, because of floating condition, has an inherent tendency to become unstable during grinding. This is particularly true in the case of hollow workpieces like bearing races, bushes, cylinder liners, etc. In this paper, an attempt has been made to investigate the dynamic instability of the workpiece and to identify its effects on the quality of ground parts in infeed grinding. The details of the experimental investigations carried out to measure the horizontal and vertical movements of the workpiece directly on the machine are included. Some measures to minimize the vertical movement of the workpiece and to improve the quality of the ground part are also discussed.
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    Effect of top-relief and rake angles on the gear shaping cutter profile
    (01-01-1983)
    Srinivasan, N.
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    Gear shaping cutters are provided with top-relief and rake angles. As a result of this, the profile representing the cutting edge is modified. This paper deals with the method of obtaining the effective profile on the rack-type and pinion-type cutters for spur gears. Analysis of the effective profile shows that the effective profile of the rack-type cutter is actually a straight-sided tooth form with different pressure angle and tooth thickness at the reference (pitch) line. In the case of the pinion-type cutter, tooth thinning takes place and the effective profile could not be identified with any involute form. This paper also deals with the methods of correcting the cutter profile form so that profile close to the theoretical form can be obtained on grinding the rake face. This approach would be quite useful to the designers and manufacturers of the shaping cutters. © 1983, Institution of Mechanical Engineers. All rights reserved.