Paper delivery for web offset printing press

Abstract: A snubber (10) is provided with a guide member (25) which is capable of gradually peeling paper from an upper high-speed belt (6) to completely drop the rear end of paper onto the low-speed belt (7), thereby enabling good paper dodging.

Description: Background of the Invention This invention relates to a paper delivery for a web offset printing press of a type which discharges paper by shiftedly stacking paper by retardation on a low-speed belt, like a sheeter. A rolled web offset printing press is provided with a folder which cuts the web, which is printed, dried and cooled, to a predetermined length, or folds it in the cross or longitudinal direction of the web into so called "signatures". Heretofore, in this type of folder, the completed signature which is intermittently fed has been dropped one by one between blades of a fan wheel, rotated, and dropped on a delivery conveyor to be discharged in a shiftedly stacked state. However, in a paper delivery using a fan wheel, because space (paper delivery pitch) between signatures must be set large to put the signatures into the wheel and in turn the transportation speed of the belt must be increased, a high-speed machine has had a problem in that it is difficult to stably drop the signatures between the fan wheel blades. Furthermore, as the machine speed increases, the retardation ratio before the signature enters the fan wheel becomes large, which tends to cause flaws and scratches on the signatures. If the diameter of the fan wheel is increased to decrease the difference between the peripheral speed of the wheel and the feed speed of the signatures in order to prevent the above problem, the device tends to become larger in size. The inventors formerly invented a paper delivery which utilizes a sheeter to cut the web into cut sheets and stack them, thereby increasing the speed of the folder. Since, in the above-described paper delivery, signatures are shiftedly stacked or shingled by retardation on a low-speed belt and discharged, above the low-speed belt are disposed a snubber for regulating the vertical relative positions of the foregoing signature and following signature to make paper dodging and retarding the signature by snapping the rear end of the signature between the snubber and the low-speed belt, and a braking roller for retarding the signature down to the speed of the low-speed belt to shiftedly stack the signatures. Furthermore, the outlet side of an upper one of a pair of high-speed belts overlaps the inlet side of the low-speed belt. Therefore, as the machine speed increases, the signature tends to strongly hit the braking roller resulting in a damage at the front edge, or the signature tends to be strongly nipped instantaneously between the snubber and the low-speed belt resulting in scratch marks at the rear end of the signature. When, to prevent the signature from strongly hitting the braking roller, the braking roller is moved towards the paper delivery direction, paper dodging between signatures becomes impossible resulting in paper jamming, or, when the rear end of the signature is caused not to be nipped in order to eliminate scratching with the snubber, the unretarded signature hits the braking roller resulting in increased damages to the front edge. Consequently, the signatures can be handled at a rate of no more than 600 units per minute even if a best condition is set where no flaws or damages are caused on the signatures. Furthermore, because of the difference in height between the low-speed belt and the upper high-speed belt with increasing machine speed, even if the rear end of the signature is pushed down by the snubber to deflect the signature down onto the low-speed belt, the signature tends to move down only partly due to the inertia in association with the high speed, which causes unstable dodging between signatures resulting in paper jamming. EP-A-0 244 650 discloses a sheet diverting and delivery system which comprises the features listed in the preamble of claim 1. Its guide member is formed by two snubber wheels which are mounted on a snubber support plate. The wheels snub the sheets against flat belts slightly before the lowest point of their rotation, thereby decelerating the sheets. By this snubbing action the rear end of the paper is rapidly pushed down, whereas the other part is still left up so that the next following signature may hit the upstanding part and paper jamming may occur. Object of the Invention Therefore, it is a primary object of the present invention to provide a paper delivery for a web offset printing press, which does not cause flaws or scratches to paper and enables good paper dodging even when the machine speed is increased. Summary of the Invention According to the present invention, the invention provides a paper delivery for a web offset printing press as claimed in claim 1. With the above arrangement, since paper is peeled gradually and entirely from the upper high-speed belt by the guide member of the snubber, the rear end of paper is completely moved down onto the low-speed belt. Brief Description of the Drawings Fig.1 is a schematic side cross sectional view of a folder showing an embodiment of the present invention. Fig.2 is a schematic enlarged side view showing part of Fig.1. Fig.3 is a schematic cross sectional view of Fig.2. Fig.4 is a schematic side view of a snubber used in this embodiment. Fig.5 is a schematic side view of a slowdown pulley used in this embodiment. Figs.6(A) through 6(F) are schematic views showing operations of the snubber in this embodiment. Fig.7 is a schematic side cross sectional view of a snubber of another embodiment of the present invention. Detailed Description of the Preferred Embodiments As shown in Fig.1 showing a folder to which the present invention is applied, between right and left main frames 1 of a folder are arranged nipping rollers 2, 2', lead-in rollers 3, 3' a cut-off cylinder 4, a bearing cylinder 5, a high-speed belt (acceleration belt) 6, and a low-speed belt 7 in this order along the signature flow direction. As shown in Fig.2 and Fig.3, a plurality of the low-speed belts 7 is disposed between the right and left main frames 1, 1, and the discharge side of an upper high-speed belt 6a of the pair of high-speed belts 6 overlaps the feed side of the low-speed belts 7 over a predetermined length. A snubber 10 for maintaining the vertical relation between the preceding paper and the next paper is disposed above the feed side of the low-speed belt 7. The snubber 10, as shown in Fig.4, is mounted with wheels 13 through an arm 12 at symmetrical positions on the outer periphery of a rotary shaft 11, and guide plates 14 having arc-formed outer peripheral surfaces are mounted at both ends of the arm 12 and in front of the wheels 13 with respect to the rotational direction. Centers P 1 and P 2 of arc of the guide plates 14 are slightly offset from a center O of rotation of the snubber 10, so that the outer peripheral surface of the guide plates 14 gradually withdraws inside from the rotational locus C of the largest-diameter portion of the snubber 10 towards the front side of the rotational direction. In addition, the peripheral speed of the largest-diameter portion of the snubber 10 is set a little smaller than the speed of the signature. Furthermore, above the discharge side of the low-speed belt 7, a braking roller 15 for retarding the signature and shiftedly stacking or shingling them on the low-speed belt 7 is disposed between the right and left main frames 1, 1'. Moreover, above the low-speed belt 7 located between the snubber 10 and the braking roller 15, a slowdown pulley 16 for retarding the signature within a section prior to the braking roller 15, together with a paper guide 17, is disposed above the low-speed belt 7 located between the snubber 10 and the braking roller 15. The slowdown pulley 16, as shown in Fig.5, comprises semicircular rings 19a and 19b placed opposite one another with an offset in the radial direction of the rotary shaft 18, and the protruded portions form claws 20a and 20b. The paper guide 17 comprises a plurality of elongate rectangular plates supported by a supporting plate 21 disposed between the right and left main frames 1. The paper guide 17 is disposed so as to guide the signature to the slowdown pulley 16 and to the braking roller 15. Furthermore, a deflection roller 22 and first and second conveyor tables 23a and 23 b as guide means to urge the low-speed belt 7 towards the slowdown pulley 16 side are disposed at the opposite side of the slowdown pulley 16 across the low-speed belt 7. With the above arrangement, former-folded web passes through the nipping rollers 2, 2 and cut by the cut-off cylinder 4 to a predetermined length to form signatures, and the signatures are transported by the high-speed belts 6 with a predetermined pitch to be supplied onto the low-speed belt 7. On the low-speed belt 7, as shown in Fig.6(A) to Fig.6(F), a signature A 1 is gradually bent down onto the low-speed belt 7 (Fig.6(A) and Fig.6(B)), the leading edge of the signature A 1 is guided by the paper guide 17 and the low-speed belt 7 to contact against the slowdown pulley 16, thereby achieving primary retardation and leading edge registration of the signature A 1 . In this section, the rear end of the signature is dodged with the next signature A 2 (Fig.6(C) and Fig.6(D)). Then, the signature A 1 which is primary-retarded within a predetermined section indicated by an angle  is guided by the paper guide 17 to the braking roller 15, where it is finally retarded to the transportation speed of the low-speed belt 7 (Fig.6(E) and Fig.6(F). This procedure is continued to shiftedly stack a predetermined number of signatures on the low-speed belt 7, which are discharged. Since, in this embodiment, the signature is primary-retarded by the slowdown pulley 16 prior to the braking roller 15, impact of the leading edge of the signature to the braking roller 15 is reduced, thereby preventing the leading edge of the signature from being damaged. Furthermore, with such two-step retardation, it is not necessary to retard the signature by nipping the rear end of the signature between the wheel 13 of the snubber 10 and the low-speed belt 7, and a clearance can always be set between the snubber 10 and the low-speed belt 7, thereby preventing the rear end of the signature from being scratched by the snubber 10. Furthermore, in this embodiment, since the guide plate 14 of the snubber 10 gradually protrudes from the upper high-speed belt 6a to begin peeling the signature from the upper high-speed belt 6a (Fig.6(B)) and the outer peripheral surface of the guide plate 14 is arc-formed, the signature is smoothly peeled off from the upper high-speed belt and dropped down onto the low-speed belt 7. Thus, the rear end of the signature is also completely bent down onto the low-speed belt, thereby allowing good dodging with the front end of the next signature (Fig.6(E)). Consequently, this enables smooth paper delivery at a high rotational speed, and signatures can be handled at a rate of exceeding 2,000 units per minute, compared to the prior art devices which are able to handle signatures at a rate of no higher than 600 units per minute. Fig.7 shows another embodiment of the present invention. In this embodiment, in place of the wheels 13 of the snubber 10 and the guide plate 14 in the previous embodiment, a plurality of rollers 25 are supported by adequate means at both ends of the arm 12, so that the centers P 3 and P 4 of circumcircles of the rollers 25 are slightly offset of the rotational center O of the snubber 10. With this arrangement, the same functions and effects as of the previous embodiment can be obtained. The present invention is described above using a folder as a delivery. However, it is needless to say that the present invention can also be applied to sheeters having the similar arrangement which make merely cutting without folding, to obtain the same functions and effects.

Claims: A paper delivery suitable to be used with a web offset printing press and comprising a low-speed belt (7) for transporting paper, a pair of upper and lower high speed belts (6, 6a) with the outlet side of said upper high speed belt (6a) overlapped above the inlet side of the low-speed belt (7) for supplying paper to said low-speed belt (7) and a snubber (10) disposed above the inlet side of said low-speed belt (7) for maintaining a constant relation between the preceding paper and the next paper, said snubber having a rotary shaft (11) rotating in synchronisation with said web offset printing press and a guide member (13, 14) disposed at the outer periphery of said rotary shaft (11) and capable of gradually peeling the paper (A 1 , A 2 ) from said upper high-speed belt (6a), said guide member (13, 14) comprising wheels (13) mounted on an arm (12) at symmetrical positions (13) on said rotary shaft (11); characterized by: guide plates (14) having arc-formed outer peripheral surfaces disposed at both ends of said arm (12) and in front of said wheels (13) with respect to the rotational direction. The paper delivery of Claim 1 wherein the guide plates are formed by a plurality of wheels (25) supported by adequate means at both ends of the arm (12). Use of the paper delivery as claimed in Claim 1 or 2 for delivering signatures (A 1 )

Inventors: KANETA TOMOO, KIYOTA HIROTAKA, KURIHARA MASAKAZU, NAKAJIMA MASAAKI, KANETA, TOMOO, KIYOTA, HIROTAKA, KURIHARA, MASAKAZU, NAKAJIMA, MASAAKI, KANETA, TOMOO, C/O KOMORI CORPORATION, KIYOTA, HIROTAKA, C/O KOMORI CORPORATION, KURIHARA, MASAKAZU, C/O KOMORI CORPORATION, NAKAJIMA, MASAAKI, C/O KOMORI CORPORATION
Applicants: KOMORI PRINTING MACH, KOMORI CORPORATION
Application year: 1990
Main classification: B65H29
IPC codes: B65H29