The die 60 consists of two halves a

The die 60 consists of two halves a and b as will be seen in the cross-sectional view in Fig. 19. The half a is provided with a threaded opening 61 which leads to a duct or chamber 62 which. in turn, communicates with a second chamber 63. Between the said chambers 62 and 63 there is a constriction 64 which serves a very important purpose. The object of restricting the space through which the material may flow is to insure absolutely uniformity of the material before it is allowed to extrude through the orifice 65. The width of the constriction 64 is so chosen that approximately as much material may pass between it as will be extruded from the lower chamber 63. It will readily be understood that by reason of the highly insulating qualities of the dough passing through the heating tubes 53 the center of the moving mass of plastic dough will not be quite as hot as those portions that are in close proximity to the sides of the said tubes. As the material enters the crown or dome 55 from the tubes 53, a certain amount of mixing will take place. but this will not be quite sufficient for perfect operation.