Intermediate roller for joining water and ink in printing machine

The utility model discloses a middle roller used to connection water and chinese ink at a printer, including a major axis component, a roll form covered on the major axis component, and a left shaft centre component, an inner gear component, a gear assembly, a connector component, a cam pack, a shaft sleeve component, a right shaft centre component furnished on the major axis of the major axis component in the roll, as well as a left and a right countercheck piece mounted separately at the two terminals of the roll and presses the inner gear component and the shaft sleeve modular, respectively, characterized in that: the core axises of the left and the right shaft centre component are provided with sheaths between the left countercheck piece and the inner gear, and between the shaft sleeve component and the right countercheck piece seperately via bearing. The utility model has the advantages of small radial jump, equilibrious connection of water and Chinese ink and symmetrical inking, and can satisfy the request of printing with higher quality.