Roller mill
A roller mill is a grinding machine ( grinding mill ), in which the material to be ground is broken and crushed between rotating rolls. This type of mill is now the most widely used in industrial mills.
Apart from the use in mills roll mills are used in calendering.
Operation
The milling in the modern mill comprises two processing operations that are repeated several times: crushing and screening. The roller mill grinding done. Here, the endosperm is achieved in several steps gently from the shell parts. The resulting mixture is passed to a plan sifter for separation. The coarse particles that are not yet flour are passed back to the roller mill by means of pneumatic or mechanical modes. A passage through the rolling chair and plan sifter is called "Passage". The " crushing " the grains are broken up by corrugated rolls, separated the " dissolving " ( by burnishing ) the flour and shell parts from each other and the " grinding a " the last flour particles are detached from the shell. The grain passes through eight to twelve passages before the flour is dissolved from the shell.
In a closed housing the grain falls into the upper end of the roller mill. There, a feed roller feeds it, while ensuring a constant flow rate to the grinding gap. This is formed by two horizontally or diagonally arranged rollers ( like gears ) are in opposite directions.
The Miller case has different settings:
- Distance between the rolls ( mill gap )
- Differential speed (leading with fluted rollers 1:2.5 and 1:1.25 burnishing )
- Number of Riffel
- Riffel angle ( twist )
- Position of the bumps each other (back: back, back: Cutting, Cutting: Cutting, Cutting edge: back)
Roll mills are now controlled and monitored electronically.
Modern roller mills in a flour mill
Historical roll mill
Supply
In a modern roller mill, the speed of the feed roller is regulated according to the information of a weight sensor in Vordepot. In older versions a plate controls in Vordepot the supply, by acting on a mechanical system. The speed of the feed roller is fixed to a lever by the miller. The speed of the feed roller and the opening of the power supply is very important for the grinding and the downstream machine, since these can be overloaded with too high impingement.