Power Rating of Single and Double Helical Gearing for Rolling Mill Service
The AGMA Mill Gearing Committee recently completed the development of a new standard, ANSI/AGMA 6015-A13 “Power Rating of Single and Double Helical Gearing for Rolling Mill Service”.
The purpose of ANSI/AGMA 6015-A13 is to provide a method for determining the power rating of gear sets used in main mill drives, pinion stands, and combination units for metal rolling mills. This standard has been developed to address the fundamental differences between typical enclosed drive applications and rolling mill applications. The new standard has its roots in ANSI/AGMA 2001-D04 and ANSI/AGMA 6005-B89. Some of the main elements of this new standard include;
- A method to compare different gear tooth designs at the extended life cycles typical for these applications,
- Face widths in excess of the 40 inches limitation contained within previous standards are also accommodated
- A calculation method for load distribution factor, Km, at these extended face widths.
The standard also addresses the range of load spectra experienced by these drives and defines load sharing for two and three high mill pinion stands.
Furthermore, the stress cycle factor for pitting resistance, ZNR, consists of a single curve above 107 cycles, and its value has been modified based on current practice. The stress cycle factor for bending strength YNR, consists of two curves above 107 cycles, one for gears with shot peened roots, and the other for gears with untreated roots. Below 107 cycles, both ZNR and YNR are assigned a value of unity. In addition, the surface condition factor for pitting resistance, CfR, is assigned values other than 1.00 depending on the composite surface finish of the tooth flanks of both mating elements, and a new surface condition factor for tooth root bending, KTRF, has been created and is assigned values depending on the surface finish for the tooth root fillets of the gear in question.
Finally, annexes are included in this standard to give guidance on such subjects as service factors, shaft design, and blank configuration.
The new ANSI/AGMA 6015-A13, and its metric edition ANSI/AGMA 6115-A13, are available for purchase, in electronic format, on the AGMA website at http://www.agma.org; click on the “STANDARDS” button.
The AGMA Mill Gearing Committee wishes to thank all participants for their valuable contributions during the development of these new standards.
To find out how you can get involved with any of the AGMA committees which actively serve the industry, contact Headquarters at tech@agma.org for details.
