Agricultural Machines

[brian6953]

Does anyone know how to calculate ideal tip speed, cutter angle,blade thickness and torque required for a rotary grass cutting blade driven by a battery powered electric motor.

 

[dwt]

You have a lot of items listed that are going to affect each other and they will all depend on the type of grass and the conditions (moisture content,amount of foreign debris, etc) you are cutting in.
Start off by benchmarking existing or similar units in the market. What are they using for tip speed, blade thickness and cutter angle. Check with OPEI (Outdoor Power Equipment Institute) regarding standards and best practises. ANSI/OPEI B71.4 Safety Specifications for Commercial Turf Care Equipment specifies a maximum tip speed of 19,000 ft/min.
Is your electric motor your limiter? Then work from there as to your maximum torque available and tip speed, etc.

 

[okeng]

dwt is right about benchmarking existing machines. I think that performance in cutting goes up with tip speed (just gut feel based on running a variety of machines) but your horsepower requirements go up a lot because of the aerodynamic resistance. I'm not sure where the sweet spot is.

You might also benchmark disc swathers--they seem to have a lot of research behind them, and everyone in the industry seems to have landed in about the same place.

Jess Davis
Davis Precision Design

 

[reheological]

you need to read more reviews on grrasses and their engineering/ physical properties.