Provides a code of practice dealing with inspection relevant to tangential element and composite deviations of cylindrical involute gears measurements referred to single flank contact. ISBN: Pages: Your Alert Profile lists the documents that will be monitored. If the document is revised or amended, you will be notified by email. You may delete a document from your Alert Profile at any time.
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Any person who refers to any AGMA technical publication should be sure that the publication is the latest available from the Association on the subject matter.
Published by. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior written permission of the publisher. Notation and numbering for external gear. Effect of contact transfer on the profile component in a tangential composite deviation diagram spur gears. Symbols and definitions. This document was approved by the Inspection Handbook Committee on January 31, Suggestions for improvement of this document will be welcome.
Consultant Profile Engineering, Inc. Gear Metrology, Inc. Caterpillar, Inc. Atlas Copco Comptec, Inc. Consultant R. Luetkemeier D. Mitsubishi Gear Technology Ctr. Nippon Gear Company, Ltd. Brad Foote Gear Works, Inc. Hamilton Sundstrand Aero. Fairfield Manufacturing Co.
Columbia Gear Corporation. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this document are encouraged to investigate the possibility of applying the most recent editions of the standards indicated.
In all cases, the first time that each symbol is introduced, it is defined and discussed in detail. See table 1. The user should not assume that familiar symbols can be used without a careful study of their definitions.
Definition1 Facewidth Design pitch diameter Design base diameter Reference diameter Effective base diameter Tolerance diameter Total helix deviation. Where first used Figure 24 Eq 4 Eq 3 Eq 24 6. Where first used 9. Table 1 concluded Symbols R r s z zM z1 z2 Tt n n eff t t eff.
Definition1 Right flank Right hand helix Undulation measurement bar length Number of teeth Number of teeth in master indexing worm wheel Driving gear Driven gear Transverse pressure angle at the tolerance diameter Normal pressure angle Effective normal pressure angle Design transverse pressure angle Effective transverse pressure angle Helix angle Design base helix angle Effective helix angle at the standard pitch diameter Effective helix angle at the tolerance diameter Total contact ratio Undulation wave length Axial wavelength of undulation Involute roll angle Reference face Non--reference face.
Units -- -mm -- -degrees degrees degrees degrees degrees degrees degrees degrees degrees -- -mm mm degrees -- Where first used 5.
NOTE: 1 Symbols used for deviations of individual element measurements from specified values are composed of lower case letters f with subscripts exceptions include fe, f1 and f2 whereas symbols used for cumulative or total deviations, which represent combinations of several individual element deviations,are composed of capital letters F also with subscripts.
It is necessary to qualify some deviations with an algebraic sign. A deviation is positive when e. Certain elements may not significantly influence the function of the gear under consideration.
Some measurements can be substituted for others. Stable manufacturing processes allow a relatively small number of samples to be measured and still ensure that the required quality level is maintained. It is recommended that specific measuring plans be negotiated between purchaser and supplier. The information required will vary depending on the type of measurement s required.
Most measurement. Certain measuring tasks require additional information. For example, to measure profile, the profile control diameter and start of tip break must be provided. With mechanical measuring equipment, additional information may be required: base circle diameter radius , base helix angle, sine bar setting, etc. The design engineer or engineering department should be responsible for supplying this minimum required inspection information to those performing the measurements.
Some measurements may be. For example single flank composite measurement may be substituted for pitch measurement, or radial composite measurement may replace runout measurement. A number of factors should be considered when selecting the measurements, including the quality level required, size of the gear, manufacturing cost and most important the application of the product gear. When the process used is proven capable of producing the required accuracy level using statistical methods, sampling inspection may be utilized.
Many factors may influence the sample size and frequency, foremost among these should be the assurance that the required accuracy level of the parts is met. Ideally the surfaces used to construct the datum axis, the surfaces used to locate the gear for manufacturing, and the functional surfaces that define the gear axis of rotation in its final assembly would all be the same.
In practice this is often not the case. For example, shaft type parts are often manufactured and inspected using female centers to define the datum axis. The gear being measured should be oriented so that its datum axis is coincident with the axis of rotation of the measuring instrument. In the case of mounting the gear between centers, care must be taken to assure that the mounting arbor, if used, is in good condition, and the female centers are clean and concentric with the datum surfaces of the gear.
In the case of computer controlled measuring instruments, it may be possible to mount the gear with significant deviation to the instruments axis of rotation. In that case, the measuring program must be capable of mathematically correcting the errors resulting from this off axis mounting condition.
In the following, conventions are described which enable positive determination of the location of deviations. It is defined by specification of datum surfaces. The datum axis determines tooth geometry, thereby being the reference for measurements and associated tolerances. The location and orientation of the tolerance diameter circle are determined by the datum axis.
It is convenient to choose one face of the gear as the reference face and to mark it with the letter I. The other non--reference face might be termed face II.
For an observer looking at the reference face, so that the tooth is seen with its tip uppermost, the right flank is on the right and the left flank is on the left. Right and left flanks are denoted by the letters R and L respectively.
The hand of helix is denoted by the letters r and l respectively. The helix is right hand left hand if, when looking from one face, the transverse profiles show successive clockwise counter--clockwise displacement with increasing distance from an observer. The tooth number is followed by the letter R or L,.
The numbering of individual pitches is related to tooth numbering as follows: pitch number N lies between the corresponding flanks of teeth numbers N and N; with a letter R or L it is indicated whether the pitch lies between right or left flanks. For example Pitch 2 L, see figures 1 and 2. In practice, a number is substituted for k, for example Fp3 indicates that a given cumulative pitch deviation refers to three pitches. Index, single pitch fpt , and total cumulative pitch Fp are elemental parameters relating to the accuracy of tooth locations around a gear.
The following is a description of the measuring methods and a guide to the interpretation of data generated by the measuring devices.
Measurements made at different diameters or in other directions must be adjusted so that they are equivalent to measurements at the tolerance diameter and in the tolerance direction.
This adjustment must be made before comparison of test results to tolerances. Measurements of sector pitch deviation are also expected to conform to the above specified requirements. Pitch should be measured on both left and right flanks. However, if the specific operating direction of the gear is known, only the loaded flanks need to be measured. The indexing single probe device determines the location of each tooth around a gear, relative to a datum tooth the index.
The pitch comparator two probe device compares the distances between adjacent tooth flanks to the distance. The various pitch parameters can all be determined by either measuring device with the application of suitable calculations.
The indexing method is usually preferred because of its accuracy and simplicity. However, for large diameter gears, use of the pitch comparator method may be preferable. Coordinate measuring machines without a rotating table can also be used for measurements of pitch parameters by probe movements that correspond to the principle of the indexing method.
The degree of its precision must be consistent with the quality grade and diameter of the gear. It is common practice to complete this series of measurements by taking a final measurement on the initial reference tooth, thereby closing the circle. Ideally, this would produce a second measurement value of zero for the first tooth, as was set at the beginning of the process.
Excessive deviation of this second measurement value from zero indicates a problem with the measurement. Left flank single probe measurement values must be multiplied by 1 to produce plus and minus index values. Other pitch parameters may then be calculated from that data. If a graphical recorder is used, data gathered by the single probe measurement device will appear in the form shown in figure 4.
This figure shows the measurement value of the initial measured tooth set to zero, thereby establishing it as the reference. The measured values shown for all other teeth then represent the positional deviations of those teeth from the initial reference tooth. See Clause 5 for specified tooth numbering, pitch numbering, and flank naming conventions.
The number 1 single pitch deviation value is equal to the index value of the last tooth subtracted from the index value of the first tooth.
The number 2 single. Since the index value of the first tooth is set to zero, the number 2 single pitch deviation value is equal to the index value of the second tooth. The number 3 single pitch deviation value is equal to the index value of the second tooth subtracted from the index value of the third tooth, and so on. The single probe should be oriented to contact the tooth flanks at the tolerance diameter, dT, and to gather measurements in the specified measurement direction.
AGMA 915-1-A02 Gears Inspect