PRINTING PRESS

1 . A printing press comprising a plate replacing apparatus, wherein the plate replacing apparatus includes

a new-plate holding unit that holds a surface of a new plate in a width direction on a new-plate insertion path;

a movement constraining unit that constrains the new-plate holding unit to move in a direction of inserting the new plate between the new-plate holding unit and a frame in which the new-plate holding unit is mounted, with a margin in the width direction of the new plate;

a pressing unit that presses the new-plate holding unit in a direction in which the new-plate holding unit is constrained with a constant force by a distance equivalent to a moving distance of the new plate held by the new-plate holding unit to be inserted towards a plate cylinder; and

a position returning unit that presses the new-plate holding unit to be returned from a position where the new-plate holding unit is pressed to a position where the new-plate holding unit is located before being pressed.

2 . A printing press comprising a plate replacing apparatus, wherein the plate replacing apparatus includes

a new-plate holding unit that holds a surface of a new plate in a width direction on a new-plate insertion path;

a movement constraining unit that constrains the new-plate holding unit to move in a direction of inserting the new plate by fitting a columnar lug protruded from the new-plate holding unit in the width direction of the new plate in a groove provided on a frame in which the new-plate holding unit is mounted; and

a plate-introduction rotating unit that is an approximately horseshoe-shaped rotating unit, the plate-introduction rotating unit holding the columnar lug protruded from the new-plate holding unit on its lower jaw before the new plate is inserted towards the plate cylinder, releasing the columnar lug protruded from the new-plate holding unit in the direction in which the new plate is inserted by rotating downwards when the new plate is inserted towards the plate cylinder, and defining an angle when the plate-introduction rotating unit stops rotating as an angle when the columnar lug contacts neither an upper jaw nor the lower jaw in a state that a notch provided at a tip of the new plate is fitted in a pin of the plate cylinder, and also when the columnar lug is pressed by the upper jaw in a state that the notch is located short of a position where the notch is fitted in the pin.

3 . A printing press comprising a plate replacing apparatus, wherein the plate replacing apparatus includes

a new-plate holding unit that holds a surface of a new plate in a width direction on a new-plate insertion path;

a movement constraining unit that constrains the new-plate holding unit to move in a direction of inserting the new plate by fitting a columnar lug protruded from the new-plate holding unit in the width direction of the new plate in a groove provided on a frame in which the new-plate holding unit is contained, with a margin in the width direction of the new plate; and

a plate-introduction rotating unit that is an approximately horseshoe-shaped rotating unit, the plate-introduction rotating unit holding the columnar lug protruded from the new-plate holding unit on its lower jaw before the new plate is inserted towards the plate cylinder, releasing the columnar lug protruded from the new-plate holding unit in the direction in which the new plate is inserted by rotating downwards when the new plate is inserted towards the plate cylinder, and defining an angle when the plate-introduction rotating unit stops rotating as an angle when the columnar lug contacts neither an upper jaw nor the lower jaw in a state that a notch provided at a tip of the new plate is fitted in a pin of the plate cylinder, and also when the columnar lug is pressed by the upper jaw in a state that the notch is located short of a position where the notch is fitted in the pin.

4 . A printing press comprising a plate replacing apparatus, wherein the plate replacing apparatus includes

a new-plate holding unit that holds a surface of a new plate in a width direction on a new-plate insertion path; and

a roller guide that exposes the surface of the new plate held by the new-plate holding unit, the roller guide including a torque limiter.

5 . A printing press comprising a plate replacing apparatus that includes a mechanism for removing an old plate wound around a plate cylinder, wherein

the mechanism includes plate-holding guide rollers for holding the old plate, and

a one-way clutch is provided on at least one of the plate-holding guide rollers.