Air cushion guide and method of adjusting a flotation height

In a delivery system of a sheet-fed offset printing press, an air cushion guide for sheet or web-formed material, comprising:

• at least one guide member formed with nozzle openings through which air is blown between said guide member and the guided material for supporting the guided material on a supporting air cushion located above said guide member;
• said guide member formed with at least two chambers extending side by side along a direction of travel of the guided material;
• said nozzle openings including a first group of nozzle openings characterizable by a first characteristic curve and communicating with a first one of said chambers, said first characteristic curve relating volumetric air flow emerging from said first group of nozzles to a pressure in said first one of said chambers;
• said nozzle openings including a second group of nozzle openings characterizable by a second characteristic curve and communicating with a second one of said chambers, said second characteristic curve relating volumetric air flow emerging from said second group of nozzles to a pressure in said second one of said chambers;
• said second characteristic curve being different from said first characteristic curve;
• and wherein:
• at least one of two variables consisting of volumetric air flow emerging from the nozzles and flow speed of the air between the guide member and the guided material are adjustable independently of one another.

In a region wherein one of a sheet transfer device and a sheet turning device is located between two impression cylinders of a sheet-fed offset printing press, an air cushion guide for sheet or web-formed material, comprising:

• at least one guide member formed with nozzle openings through which air is blown between said guide member and the guided material for supporting the guided material on a supporting air cushion located above said guide member;
• said guide member formed with at least two chambers extending side by side along a direction of travel of the guided material;
• said nozzle openings including a first group of nozzle openings characterizable by a first characteristic curve and communicating with a first one of said chambers, said first characteristic curve relating volumetric air flow emerging from said first group of nozzles to a pressure in said first one of said chambers;
• said nozzle openings including a second group of nozzle openings characterizable by a second characteristic curve and communicating with a second one of said chambers, said second characteristic curve relating volumetric air flow emerging from said second group of nozzles to a pressure in said second one of said chambers;
• said second characteristic curve being different from said first characteristic curve;
• and wherein:
• at least one of two variables consisting of volumetric air flow emerging from the nozzles and flow speed of the air between the guide member and the guided material are adjustable independently of one another.

A method for adjusting a flotation height of sheet or web material guided in an air cushion guide, which comprises:

• providing at least one guide member formed with nozzle openings;
• providing the guide member with a first chamber communicating with a first group of the nozzle openings and a second chamber communicating with a second group of the nozzle openings, the first chamber and the second chamber extending side by side along a direction of travel of guided material;
• configuring the first group of nozzle openings and configuring the second group of nozzle openings such that a first characteristic curve, relating volumetric air flow emerging from the first group of nozzles to a pressure in the first chamber, is different than a second characteristic curve, relating volumetric air flow emerging from the second group of nozzles to a pressure in the second chamber;
• supporting the guide material on a supporting air cushion via the guide member;
• blowing air beneath the guide material via nozzles in the guide member;
• and
• varying a quotient between volumetric air flow blown in through the nozzles and flow speed of the air between the guide member and the guide material.

An air cushion guide for sheet or web-formed material, comprising:

• at least one guide member formed with nozzle openings through which air is blown between said guide member and the guided material for supporting the guided material on a supporting air cushion located above said guide member;
• said guide member formed with at least two chambers extending side by side along a direction of travel of the guided material;
• said nozzle openings including a first group of nozzle openings characterizable by a first characteristic curve and communicating with a first one of said chambers, said first characteristic curve relating volumetric air flow emerging from said first group of nozzles to a pressure in said first one of said chambers;
• said nozzle openings including a second group of nozzle openings characterizable by a second characteristic curve and communicating with a second one of said chambers, said second characteristic curve relating volumetric air flow emerging from said second group of nozzles to a pressure in said second one of said chambers;
• said second characteristic curve being different from said first characteristic curve;
• said first group of nozzle openings supplied by blown air at a pressure that is regulatable independently from a pressure that is supplied to said second group of nozzle openings.

A method for adjusting a flotation height of sheet or web material guided in an air cushion guide, which comprises:

• providing at least one guide member formed with nozzle openings;
• providing the guide member with a first chamber communicating with a first group of the nozzle openings and a second chamber communicating with a second group of the nozzle openings, the first chamber and the second chamber extending side by side along a direction of travel of guided material;
• configuring the first group of nozzle openings and configuring the second group of nozzle openings such that a first characteristic curve, relating volumetric air flow emerging from the first group of nozzles to a pressure in the first chamber, is different than a second characteristic
• curve, relating volumetric air flow emerging from the second group of nozzles to a pressure in the second chamber;
• supporting the guide material on a supporting air cushion via the guide member;
• blowing air beneath the guide material via nozzles in the guide member;
• and
• varying a ratio of pressure of blowing air supplied to the first group of nozzle openings and pressure of blowing air supplied to the second group of nozzle openings.