Patent Application
20050277504
The present invention relates to controlling the motion of moving webs of indefinite length, and more particularly to a device for changing the direction or inverting such webs.
Numerous commercial products incorporate material that has undergone processing in the form of a web of indefinite length material during some stage of its manufacture. When such webs are being processed, it is frequently desirable to divert the web to a different direction, or to invert the web so the opposite side of the web is facing upwards to receive, e.g., the application of a coating. For many applications it is conventional to wrap the web partially around one or more non-rotating air flotation devices called “air bars” or “air turns” in order to divert or invert the web. However, in some circumstances the use of an air bar is inconvenient. For example the web may be too heavy, too porous, or too textured for the needed air cushion to develop. In such circumstances, it is known that apparatuses that have, e.g., guide rotors disposed in spiral curves may be employed. However, these alternatives are bulky and complicated to construct.
Co-pending and coassigned U.S. patent application Ser. No. 10/676,188, “Apparatus For Deflecting or Inverting Moving Webs,” discloses a slat roller with a roller body having a longitudinal axis. A plurality of slats are mounted on a circumference of the roller body in such a fashion that the slats may translate from a first position in a direction parallel to the longitudinal axis of the roller body. While this is effective for diverting or inverting webs that cannot use an air turn, the slats on this slat roller must reverse direction twice per revolution to travel from a starting position to a translated position, then return. This requirement places a practical limit on the ultimate web speed that the roll can deal with. Further, this slat roller operates best when the wrap angle of the web with respect to the roller is 180 degrees or less.
The present invention provides a diverting roller for controlling the movement of moving web of indefinite length material. Such a diverting roller has a roller body having a longitudinal axis. A plurality of pairs of pulleys are rotatably mounted on the roller body adjacent a circumference of the roller body. An endless belt is looped around each of the pairs of pulleys in such a fashion that each belt has substantial portion oriented in a direction parallel to the longitudinal axis of the roller body. The travel of belts around their respective pulleys permits a non-normal angle of incidence of the web to the longitudinal axis. A non-normal angle of incidence to the longitudinal axis indicates that the centerline of the web is not at about 90 degrees with the longitudinal axis of the roller as the web makes contact with the endless belts of the diverting roller.
In another aspect the present invention provides a system for inverting a moving web of indefinite length material, the heart of which is a pair of diverting rollers. Each diverting roller has a roller body having a longitudinal axis. A plurality of pairs of pulleys are rotatably mounted adjacent the circumference of the roller body. An endless belt is looped around each of the pairs of pulleys in such a fashion that each belt has substantial portion oriented in a direction parallel to the longitudinal axis of the roller body. In a preferred embodiment, the system also has a first and a second roller for conveying the moving web between the first and the second diverting rollers, such that when the moving web, starting in a first orientation, is directed around the first diverting roller, the first and second idler rollers and the second diverting roller, it emerges in a second orientation which is inverted from the first orientation.
In a most preferred embodiment of the system the two diverting rollers are rotatably mounted with their longitudinal axes generally perpendicular to each other. Also, in most convenient embodiments, the roller body is rotated and the endless belts are caused to travel around their respective pulleys in a passive manner in contact with the moving web. The travel of the belts permits a non-normal angle of incidence of the web to the longitudinal axis of the diverting roller.
In the several figures of the attached drawing, like parts bear like reference numerals, and:
Referring now to
The non-normal angle of incidence of the web to the longitudinal axis of the diverting roller is suitable for either inverting a web or changing the orientation, or direction, of the web. The non-normal angle of incidence and the travel of the belts around their respective pulleys permit the axial movement of the web when the web is in contact with belts of the diverting roller. In general, the contact surface between the web and the belts is a greater distance from the roller axis than the outer surfaces of the roller body such that the web will contact the belts and not the roller body.
Referring now to
Referring now to
The depicted embodiment of diverting roller 20 includes nine pulley pairs 42 each supporting one endless belt 44. At least two belts 44 must be provided, but it is frequently desirable to provide more, particularly when the system 10 is operating with the diverting rollers 20 and 22 being passively driven by contact with the moving web 12. It will be appreciated that although providing more belts 44 and pulley pairs 42 will increase the cost and complexity of a diverting roller 20, the greater number of belts reduces the force applied by the web to an individual belt. The diameter of the roller body 40 and its length will also be seen to be variables affecting the amount of force the web 12 imparts to the belts 44 to cause them to travel around their respective pair of pulleys 42. It is contemplated that properly constructed diverting rollers 20 according to the present invention may be operated in connections with very high web speeds, up to or above 1000 fpm.
The preferred embodiment of the present invention has been described utilizing the moving web as the primary driving force for imparting motion to the endless belts and for imparting rotation of the roller or rollers. Those skilled in the art recognize that driven rollers and/or belts may be desirable for certain webs or web processing environments. Various modifications and alterations of the present invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not limited to the illustrative embodiments set forth herein.
