Start here to design, analyze, or dimension a gear set.
In response to the gear market’s need for optimization software, which has been lacking many years, Excel Gear Inc, Roscoe, Ill., has developed Excel-Lent gear/gearbox design and analysis software. This program is written in Visual Basics.Net by engineers who also design and manufacture gears for their own use, according to company president N.K. “Chinn” Chinnusamy.
“Although commercial software has long been available in the gear industry, it has been too expensive or complicated for use by engineers without specialized gear design knowledge,” says Chinnusamy. “Our software is specifically designed with a user-friendly interactive input screen providing defaults and options in accordance with the AGMA 2001 standard.” Users of Excel-Lent software can easily navigate through the input screens to edit, analyze, and produce reports on optimum gear and gearbox design for various industrial and other applications.
Many gear uses
“This software is not designed for any specific industry,” continues Chinnusamy. It can be used for machine tools, heavy materials handling equipment, and even the wind-turbine industry. For the wind-turbine industry, designers need a full understanding of all the operating loads on the gear members to arrive at the required power rating.
One input screen lets users select the type of gear, a material, and allowable stress levels. Some results appear in the green boxes.
Key calculations include the AGMA (American Gear Manufacturers Association) power rating and load calculations, including bending strength geometry factor (J) and pitting resistance geometry factors (I). Output from the software is a single page of data printed in a format that is easy to read and interpret. Other commercial software typically prints five or six pages of information, which may be confusing to most design engineers unless they are gear experts, Chinnusamy further observed.
The users of Excel-Lent need not be familiar with AGMA standards to use this software. Those who are not gear engineers can also benefit from the gear engineering knowledge embedded in the software package.
The software contains three sections: design, analysis, and gear dimensions. Any of the sections can be used individually to run calculations. On a typical job, according to Excel Gear, hundreds of hours typically spent doing the calculations can be saved.
A closer look at each section
DESIGN: This section calculates gears sizes based on minimal user input. The user must specify only the input rotational speed, gear ratio, power to be transmitted, and the material and heat treatments selected from material tables of commonly used materials in the industry.
Key values calculated are the diameter and face width of the pinion required for the surface-fatigue power rating and optimized DP or module (based on the calculated diameter) required for the bending fatigue power rating. The data are automatically exported to the analysis program. Results are the power ratings for 5,000 to 100,000 hours of B1 life (A reliability factor of 1).
When required, other values such as face width or center distance may be entered but Excel Gear recommends leaving the face width and center distance values blank for an optimized gear design. Design and analysis programs are used to design one gear stage in sequence on an external or internal spur and helical gear mesh.
ANALYSIS: This program calculates the power rating of a gear set for 5,000, 10,000, 25,000, 50,000 and 100,000 hours of B1 life, a reliability factor of 1. Reliability factors of 1, 1.25, or 1.5 can be selected as required. The user must input a mesh type (spur, helical, internal and external), pressure angle, helix angle (if applicable), pinion speed, number of teeth in pinion and gear, material (from the list provided in the software), face width, DP or module and quality required. Crown and/or profile shift, if used, can also be entered. The program calculates the power rating of the gear set and shows HP or KW capability along with torque, tangential force, and static capacity. Static capacity is based on yield strength and, if bending stress exceeds yield strength, permanent deformation or even tooth breakage may occur. If results are satisfactory, the user can print the single page results or, optionally, print all the AGMA factors used in making the calculations.
Most commercially available gear software will generate five or six pages of output along with required bending and surface fatigue strength of the gear set. Therefore, the user needs knowledge of metallurgy to select proper material and heat treatment or must consult a metallurgist.
By contrast, the Excel-Lent software program lists commonly used gear material for the user to select. When results are not as required, the user can select another material or change design criteria as required for needed results. If a special material is required, its yield, bending and contact stress numbers are easily entered. If any of the required input data are missing, the program prompts the user to supply the missing information. Metric or inch units are selected with just one click.
DIMENSIONS: In the opinion of the manufacturer, Excel-Lent gear dimension software is the most versatile program available. The program calculates manufacturing dimensions for a new pinion and gear, or calculates the dimension of a pinion or gear to mate with an existing pinion or gear. This can be done for external gears, internal gears, or a gear rack. Users need only to enter the type of mesh (spur or helical, internal, of external), pressure angle, helix angle (if helical gears), number of teeth in pinion and mating gear, DP or module and the quality of the gears.
An output sheet list the particular for a design.
The program then calculates the center distance, dimension over pins, span measurement, form diameter, roll angles and all gear tolerances to match the quality required (AGMA, DIN, or ISO). The program calculates the helix angle required to match a specified center distance when the user chooses that option.
The program displays plain English error messages when inputs are questionable or in error. For example, if the center distance is incorrect, the program will flash error messages such as, “Center distance specified is too large/small.”
The program calculates optimized profile shifts for a pinion and gear operating at a non-standard center distance, when the operating center distance is specified. If the profile shift required to operate is large and makes the top land narrow, the program will flash warning messages and display the proper profile shift amount to avoid narrow top land.
Excel-Lent software further provides users the option to balance beam strength or specific sliding of gear and pinion, if required. This is key for wind turbine gears. The program will also calculate gear blank tolerances to produce the required quality level, when shaft and bore diameters are entered.
For further information or a test demo, available on CD or onsite, contact:
Excel Gear Inc.
excelgear.com
Filed Under: Gearboxes, News, Software
