Over the years a number of patents for processing industrial hemp have been designed. The earliest we've found was 1740 with a wide array of variations and designs since then. Given the state of the industry, one might conclude that the hemp sector has missed the industrial revolution.
This is a collection of some of the patents done since 1906: 1919 1941 1949 1956 up to 2006. A few new patents have turned up.
1919 Schlichten Patent.
This was one of the few decorticators to make it to commercial use. The inventor, George Schlichten died four years later. Designs from Russian, Germany and Ireland came into the market. You can still find old Schlichten units in France and Russia from the 1960's that are still working.
Designs done over the years tend to be somewhat similar. From field designs for processing green stalk to large scale systems to process up to 10 tons per hour.
Hemp Patents 1906 - 1956
This concept came from large scale hammer mill design studies showing a different method of processing stalk. Based partly on design work done over the previous 100 years.
Hammer Mill Design
D-8 Decorticator Patent 2006