Device for folding sheets

Abstract: Pairs of prefolding and pressure rollers (3, 4 and 8, 9, respectively) of identical diameters are successively arranged for rotation in a machine frame (1). A first pressure roller (8) is stationarily mounted to machine frame (1) for rotation whereas the first prefolding roller (3) associated with this side is rotatably mounted on spring-biased support members (10) which are slidable normal to the folding direction (A). The second prefolding roller (4) is mounted for rotation in bearings (14) provided at the two ends of the roller, said bearings being installed in lever arms (15) pivotally mounted to machine frame (1). Connecting arms (21) are hinged to the bearings (14) to support the second pressure roller (9) for rotation in bearings (13). The connecting arms (21) are biased by springs (18) such that during feed-in of a prefolded stack into the nip of pressure rollers (8, 9) the springs (18) are biased by pivoting the connecting arms (21) in a way that the pressure of the second prefolding roller (4) is increased and, thus, the frictional forces exerted on the stack are enhanced.

Description: The present invention relates to a device for folding at least one sheet, said device comprising driven prefolding and pressure rollers as well as a folding bar pushing the sheet into the nip of the prefolding rollers by deforming it in the folding station to take a V-shape . In a known device of this type (DE-PS 365 688 or US-A-3954258) a sheet to be folded is moved into the nip of prefolding rollers by means of a striker, said rollers feeding the sheet when prefolded to pressure rollers for completing the folding process. If a stack of sheets consisting of a plurality of sheets is to be folded, the pressure rollers which for thickness compensation must be spring-biased against each other offer the prefolded stack of sheets considerable resistance which may damage the sheets or cause malfunctions. It is the object of the invention to provide a device of the generic type such that both a single sheet and a plurality of sheets forming a stack can be folded without causing any malfunctions . The above object is attained in that the prefolding rollers and the pressure rollers are arranged in pairs parallel to each other and successively in folding direction and are rotatably mounted, a first pressure roller of the pair of pressure rollers is rotatably supported by a stationary bearing, the first rotatable prefolding roller arranged on the same side of the folding path as the first pressure roller is stationarily mounted relative to the folding direction and, biased by a spring, movably mounted normal thereto, the second prefolding roller and the second pressure roller are rotatably mounted on connecting arms, the second prefolding roller is stationarily rotatable and moveable substantially normal to the folding direction, and springs arranged between the second prefolding roller and the second pressure roller and urging them towards the first prefolding roller and the first pressure roller, respectively, engage the connecting arms such that the pressure force of the second prefolding roller is increased by tensioning the springs when sheets to be folded move into the nip of the pressure rollers . In an advantageous embodiment of the invention, the second prefolding roller is supported by the free ends of stationarily and pivotally mounted lever arms . This arrangement enables the first prefolding roller and the first pressure roller to be moved away from each other to the extent that a possible malfunction can easily be eliminated by pivoting the lever arms . The design of the folding device according to the invention effects the pressure force of the second prefolding roller to be increased as soon as the prefolded stack of sheets moves into the nip of the pressure rollers. The sheets are hereby compressed in a way so as not to slip on one another, which effects a reliable folding process. Further features and advantages are referred to in the description of an embodiment of the invention shown in the drawing and in the subclaims. In the drawing (schematic representation) Fig. 1 shows a lateral view of the device and Fig. 2 is a partial view of the device according to Fig. 1 in a cross-section along line E-E. The device according to the invention for folding sheets is arranged on a finishing unit of a known type (not illustrated) in which individually supplied sheets, in particular copy sheets produced by a copier, are collected in a collecting station to form a stack 17. As far as the finishing unit is concerned which is attached to a copier not illustrated in the drawing, only the components necessary for understanding the invention are shown. The finishing unit may be provided with a known stapling device not illustrated in which the sheets are first collected and stapled and then moved to the folding position shown in Fig. 1. According to Fig. 1, the folding device features prefolding rollers 3, 4 and pressure rollers 8, 9 having identical diameters and being arranged in pairs parallel to each other, said rollers being rotatably mounted in bearings 2, 12, 13 and 14 in a machine frame 1 arranged in parallel and rigidly interconnected by means not illustrated. Via traction gears having chains 19, 20, the prefolding and pressure rollers 3, 4 and 8, 9 are driven by a common drive motor (not illustrated) in the folding direction "A". With its bearings 2, the first pressure roller 8 is stationarily mounted to machine frame 1 for rotation . The bearings 12 of the shaft of the rotatable prefolding roller 3 are mounted on support members 10 which are slidingly guided in respective slots (not illustrated) of machine frame 1 normal to the folding direction "A" by means of guide elements 10a. Support members 10 are biased by springs 11 in sliding direction. The bearings 14 of the shaft of the second rotatable prefolding roller 4 are mounted on the free ends 15a of lever arms 15 arranged on machine frame 1 to pivot about stationary bearings 16. On shaft ends 14 at both ends of prefolding roller 4 supported by bearings 15a connecting arms 21 are hinged (see Fig . 2) on whose other ends the second pressure roller 9 is mounted for rotation about bearings 13. The connecting arms 21 are biased by springs 18 (see Fig. 1) urging the second prefolding roller 4 and the second pressure roller 9 towards the opposite prefolding and pressure rollers 3 and 8, respectively. The connecting arms 21 and the sections of the lever arms 15 extending between the bearings 13 and 14 are arranged parallel to the folding direction "A". Above the prefolding rollers 3, 4, a known folding bar 5 is arranged which by means of a drive mechanism 6, 7 can be pushed between said rollers in the folding direction "A". According to Fig. 2, the prefolding rollers 3, 4 are provided in a known way with ring-shaped recesses 4a of a minor diameter which are arranged at intervals and into which penetrate projections 5a of a comb-shaped folding bar in a known manner. In this way, the sheets to be folded can be deeply moved into the nip of the prefolding rollers 3, 4 without exerting a great force so that they can be reliably engaged. The device operates as follows: The folding device is suitable both for folding an individual sheet and a plurality of sheets collected in the form of a stack, and in the latter case for stapled or unstapled sheet stacks 17. The sheet stack 17 is moved in the direction of the arrow "B" and positioned at a stop means (not illustrated) such that the folding line is located beneath the folding bar 5 . By starting the drive mechanism 6, 7, the folding bar 5 is moved in direction "A", deforms the sheet stack 17 to take a V-shape as indicated in Fig. 1 in dash-doted lines, and is pushed into the nip of the prefolding rollers 3, 4. The nip of the prefolding rollers 3, 4 widens by tensioning the springs 11, 18 until the prefolded stack of sheets is engaged by the rollers and transported in the direction "A". Folding bar 5 is then withdrawn opposite to the direction of arrow "A" by the drive mechanism 6, 7. When the nip of the prefolding rollers 3, 4 widens, the second prefolding roller 4 is pivoted in the direction of arrow "C" and, thus, springs 18 are biased. The springs 11 arranged on the opposite side are biased by sliding the support members 10, both pairs of springs 11 and 18 permitting the folding bar 5 to centrally penetrate into the nip of the prefolding rollers 3 and 4 and, thus, producing a correctly positioned fold irrespective of the number of sheets to be folded. The prefolded stack of sheets is transported from the prefolding rollers 3, 4 to the pressure rollers 8, 9 and urges the second pressure roller 9 and thus the connecting arms 21 aside in the direction of arrow "D" by further biasing springs 18. The now increased bias of springs 18 enhances - via connecting arms 21 - the pressure of the second prefolding roller 4 against the first prefolding roller 3 so that the prefolded stack advanced therebetween is transported at an increased pressure. This increases the frictional forces exerted on the prefolded stack which is then advanced into the nip of the pressure rollers 8, 9 without having the possibility of avoiding them. At an increased pressure of the biased springs 18, the pressure rollers 8, 9 complete the fold of the prefolded stack and advance it to a collecting bin (not illustrated). As can be seen in Fig. 1, springs 18 engage the connecting arms 21 approximately in the middle between the two roller bearings 13 and 14. The pressure force of the second prefolding roller 4 can be adjusted or altered by changing the engaging point of springs 18, e. g. by means of a setting device (not illustrated). For example, the pressure force becomes greater the closer the springs 18 are positioned at bearings 14. Deviating from the arrangement of the lever arms 15 shown in the drawing, they can be stationarily supported in a different appropriate place of machine frame 1 or a component connected therewith. It is also possible not to hinge the connecting arms 21 on stationarily pivoting lever arms 15 as illustrated but to mount them directly at the machine frame 1. For this purpose, it will then be necessary to design the bearings 14 of the second prefolding roller 4 to which the connecting arms 21 are still hinged such that they are movable in the direction of the arrow "C" but are stationarily positioned in the direction of the arrow "A" (not illustrated). Due to the otherwise similar design and arrangement of the connecting arms 21 and springs 18, the operation of the pressure enhancement is the same as described above.

Claims: Device for folding at least one sheet, said device comprising driven prefolding and pressure rollers as well as a folding bar pushing the sheet into the nip of the prefolding rollers by deforming it in the folding station to take a V-shape, wherein the prefolding rollers (3, 4) and the pressure rollers (8, 9) are arranged in pairs parallel to each other and successively in folding direction (A) and are rotatably mounted, a first pressure roller (8) of the pair of pressure rollers (8, 9) is rotatably supported by a stationary bearing (2), the first rotatable prefolding roller (3) arranged on the same side of the folding path as the first pressure roller (8) is stationarily mount d relative to the folding direction (A) and, biased by a spring (11), movably mounted normal thereto, the second prefolding roller (4) and the second pressure roller (9) are rotatably mounted on connecting arms (21), the second prefolding roller (4) is stationarily rotatable and movable substantially normal to the folding direction (A), and springs (18) arranged between the second prefolding roller (4) and the second pressure roller (9) and urging them towards the first prefolding roller (3) and the first pressure roller (8), respectively, engage the connecting arms (21) such that the pressure force of the second prefolding roller (4) is increased by tensioning the springs (18) when sheets to be folded move into the nip of the pressure rollers (8, 9). Device according to claim 1, characterized in that the second prefolding roller (4) is supported by the free ends (15a) of stationarily and pivotally mounted lever arms (15). Device according to claim 1 or 2, characterized in that the first prefolding roller (3) is rotatably mounted on slidingly guided and spring-biased support members (10, 10a).

Inventors: RIES JUERGEN C O KODAK AKTIENG, SCHERR BRUNO C O KODAK AKTIENG, RIES, JUERGEN, C/O KODAK AKTIENGESELLSCHAFT, SCHERR, BRUNO, C/O KODAK AKTIENGESELLSCHAFT, Ries, Jürgen, c/o Kodak Aktiengesellschaft
Applicants: EASTMAN KODAK CO, KODAK AG, EASTMAN KODAK COMPANY, KODAK AKTIENGESELLSCHAFT
Application year: 1992
Main classification: B65H45
IPC codes: B65H45