Conveyor and method for changing the pitch of printed products
A printing press is provided. The printing press includes a print unit printing a stream of printed products, the printed products having a first pitch. The printing press also includes a pitch changing device. The pitch changing device includes an upper roller mounted on an upper axle, a lower roller mounted on a lower axle, the upper and lower rollers forming a roller nip, and a motor driving the upper and lower rollers in opposite directions. The nip receives the stream of printed products. The motor varies the velocity of the nip and the printed products using an electronic cam velocity profile so as to alter the first pitch. A method is also provided.
1 . A printing press comprising:
a print unit printing a stream of printed products, the printed products having a first pitch; and
a pitch changing device including;
an upper roller mounted on an upper axle;
a lower roller mounted on a lower axle, the upper and lower rollers forming a roller nip; and
at least one motor driving the upper and lower rollers in opposite directions;
the nip receiving the stream of printed products;
the at least one motor varying the velocity of the nip and the printed products using an electronic cam velocity profile so as to alter the first pitch.
2 . The device as recited in claim 1 further comprising a belt for rotating the upper and lower axles.
3 . The device as recited in claim 1 further comprising a further upper roller on the upper axle and a further lower roller on the lower axle forming a further roller nip.
4 . The device as recited in claim 1 further comprising a further motor for driving the upper and lower rollers, the at least one motor driving the upper roller and the further motor driving the lower roller.
5 . The device as recited in claim 1 further comprising a controller connected to the at least one motor for varying the velocity of the nip and the printed products using an electronic cam velocity profile.
6 . The device as recited in claim 1 further comprising a second pitch changing device.
7 . The device as recited in claim 1 wherein the printed product stream is split into a plurality of streams before entering the roller nip.
8 . The device as recited in claim 1 wherein the electronic cam velocity profile is sinusoidal.
9 . The device as recited in claim 1 wherein the electronic cam velocity profile is asymmetrical.
10 . The device as recited in claim 1 wherein the electronic cam velocity profile is symmetrical.
11 . The device as recited in claim 1 wherein the pitch changing device shingles the printed products.
12 . A method for changing the velocity of printed products in a product stream comprising the steps of:
moving printed products at a first velocity and a first pitch;
rotating a nip of two rollers at the first velocity;
receiving the printed products at the roller nip; and
changing the first velocity of the roller nip and printed products to a second velocity that is different from the first velocity using an electronic cam velocity profile so as to alter the first pitch.
13 . The method as recited in claim 12 wherein the first velocity is greater than the second velocity.
14 . The method as recited in claim 12 wherein the first velocity is less than the second velocity.
15 . The method as recited in claim 12 further comprising releasing the printed product at the second velocity approximately halfway through a cycle of the electronic cam velocity profile.
16 . The method as recited in claim 12 further comprising returning the roller nip from the second velocity to the first velocity over a longer period of a cycle of the electronic cam velocity profile than changing the first velocity to a second velocity.
17 . The method as recited in claim 16 further comprising releasing the printed product at a second velocity during a first quarter of the cycle.
18 . The method as recited in claim 12 further comprising the step of shingling the printed products.
19 . The method as recited in claim 12 further comprising the step of splitting a printed product stream before receiving the printed product at the roller nip.