Belt tension/drive for pinch roller system

#The technical field of this disclosure is belt driven power transfer devices, particularly, a belt tension/drive for a pinch roller system.

#Pinch roller systems are used with machines that handle sheets of material, such as a paper folder. Paper folders are able to take sheets of paper or other material and fold them into various patterns for stuffing in envelopes or mass mailings. To accomplish the folding, the paper folder feeds paper between a pinch roller and a capstan roller. The paper path is blocked, so that the travel of the paper is stopped and the paper buckles. A second path is provided where the buckles occurs, so the blocked paper follows the second path. As the paper travels into this second path, it is grabbed by a second pinch roller and the original capstan roller, which creases the paper at the point of buckling, and drives the paper through any remaining fold processes. The blocking, grabbing, and creasing process can be repeated to form multiple folds.

#The pinch rollers must be urged toward the capstan roller, while having sufficient freedom of movement to allow for single and multiple sheets of paper of various weights to pass between the pinch rollers and the capstan roller. It is very important that all of the rollers continually driver the paper through the folder. Large degrees of paper slippage cannot be tolerated, as this will cause a bad fold and/or a paper jam. Therefore, not only do the pinch rollers have to be urged toward the capstan roller, they must all be driven simultaneously at the same surface speed. Pinch roller systems typically provide separate means to perform the functions of urging the pinch rollers toward the capstan roller and driving the pinch rollers.

#FIG. 1 shows a schematic diagram of a Single Spring Method.

#FIG. 2 shows a schematic diagram of a Multi-Spring Method.

#FIG. 3 shows a schematic diagram of Gear Driven Pinch Rollers.

#The belt tension/drive for a pinch roller system of the present invention combines means for urging a plurality of pinch rollers toward a capstan roller with means for driving pinch rollers when a pinch roller is not in contact with the capstan roller. The capstan roller is surrounded by and aligned with a plurality of pinch rollers. A resilient belt disposed about the plurality of pinch rollers urges the pinch rollers toward the capstan roller and drives any pinch roller not in contact with the capstan roller, assuring that all pinch rollers maintain the same surface speed as the capstan roller.

#FIG. 5 shows schematic diagram of a belt tension/drive for a pinch roller system made in accordance with the present invention. The bearings and bushings used to support and guide the pinch rollers and capstan roller have been omitted from the figures for clarity. A resilient belt 100 wraps around a plurality of pinch rollers 102, urging the plurality of pinch rollers 102 toward capstan roller 104. The frictional contact between the pinch rollers 102 and the capstan roller 104 drives the pinch rollers 102 to rotate when the capstan roller 104 rotates. When one of the pinch rollers 102 is not in contact with the capstan roller 104 because paper is passing between the pinch roller 102 and the capstan roller 104 and displaces the pinch roller 102, the displaced pinch roller 102 continues to be driven at the same surface speed by the travel of the belt 100 driven by the pinch rollers 102 which remain in contact with the capstan roller 104.

#The resilient belt 100 both provides pressure to the pinch rollers 102 as required to hold the pinch rollers 102 in contact with the capstan roller 104 and provides a means by which drive energy can be of transferred to one or more pinch rollers not in contact with the capstan roller 104. The resilient belt 100 can be made of any resilient, compliant material with sufficient elasticity to urge the pinch rollers 102 toward the capstan roller 104 while allowing the pinch roller 102 to move when paper is present between the pinch roller 102 and the capstan roller 104. In addition, the resilient belt 100 can have a large enough friction coefficient or sticky surface to transmit the driving force from one pinch roller to the other without substantial slippage. In one embodiment, the resilient belt 100 can be made of a polymer, such as polyurethane, although those skilled in the art will recognize that other materials are suitable for the application. Typically, the resilient belt 100 can have a durometer hardness of about 85A, but can be in the range between about 20A and 110A. A lower durometer reading, indicating a softer, more pliable polymer, is desirable for use with thicker sheets or a greater number of sheets, so the pinch rollers 102 can move away from the capstan roller 104 more easily. With proper material selection, the portion of the pinch roller 102 where the resilient belt 100 rides can be fabricated without any special treatment or surface finish and still provide good frictional contact.