Over the years a number of patents for processing industrial hemp have been designed. The earliest we've found was 1840 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 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.
Hemp Patent 1956 Planetary Design
D-8 Decorticator Patent 2006