Corn concave destination:

The segment  concave  together with a threshing drum is intended for the preliminary thresh of grain weight, and direct sifting of grain with a small amount of impurity. One of its functions is to break in case of hit in a zone of the thresh of foreign subjects such as large stones or metal details.

Structure of concave;

The concave consists from sidewalls,  rigidity edges with C-form and cross levels with openings. In openings the bars forming a trellised surface are established. Also instead of levels can use the punched leaf. The concave can have the various size and a form of holes. It allows fast combine settings for collection of a specific crop.