| 摘要 |
A system for changing the speed of conveyed sheets (10) while maintaining the sheets in register including a speed changing belt (18) operating at a constant speed to present a radial outer surface portion (24) which travels over a cylindrical guide (48) and into tangent contact with the surface of the sheet (10) traveling at a speed equal to the velocity of the incoming sheets. A portion of the speed changing belt includes an acceleration lobe (30) positioned to engage the trailing portion of the sheet and to provide a continuously increasing radius at the tangent contact portion as the belt travels around the radial outer surface portion (48) whereby the outer surface velocity of the lobe (30) and the sheet (10) in contact therewith continuously increase from the incoming speed to a desired second speed. The constant velocity speed changing belt (18) requires only a simple constant speed drive and the speed change lobe (30) attached to the belt (18) requires only a relatively small increase in the effective radius of the belt around the cylindrical guide (48) such that unacceptable vertical displacements of the sheet from the plane of travel are obviated. Only the mass of the sheet or other product being conveyed (and an upper holddown idler roll (25) if used) is subject to acceleration (or deceleration) forces as all the machine drive components run at constant velocity during the speed change, thereby minimizing the overall inertial effects. |
