Quantitative feeding assembly

An upper valve plate, a valve element and a lower valve plate are sequentially arranged in a material barrel from top to bottom, the valve element is provided with at least four material preparation channels, the at least four material preparation channels are circumferentially and evenly distributed around the axis of the valve element, the material preparation channels penetrate through the upper end and the lower end of the valve element, the upper valve plate is provided with a feeding notch, and the lower valve plate is provided with a discharging notch. A feeding notch is formed in the upper valve block and smaller than an upper port of each material preparing channel, a discharging notch is formed in the lower valve block and smaller than a lower port of each material preparing channel, and at least one material preparing channel is arranged between the material preparing channel corresponding to the feeding notch and the material preparing channel corresponding to the discharging notch. The upper port