GB2267276A

GB2267276A - Folding signatures

Info

Publication number: GB2267276A
Application number: GB9310432A
Authority: GB
Inventors: Richard Burkhard Mack
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 1992-05-29
Filing date: 1993-05-20
Publication date: 1993-12-01
Also published as: GB9310432D0; DE4217815A1

Abstract

A stream of signatures which have been transversely folded by rotary folders (figure 1) is divided into two streams, the first passing beneath folding table 16 and the second passing over folding table 25. A single folding blade 18 reciprocates vertically to cooperate alternately with the tables 16 and 25 to make longitudinal folds in sheets of the first and second streams respectively. The folded signatures of the first and second streams are fed by conveyers 28 and 31 respectively to pockets in a wheel 27, which deposits a single shingled stream on delivery conveyer 35. <IMAGE>

Description

2267276 Device for longitudinally folding signature in folding apparatus

The invention relates to a device for longitudinally folding signatures in folding apparatus designed for high-speed rotary printing presses.

In the state of the art, the Japanese Patent, published under No. 59185650 (A)., discloses a longitudinal-fold device for the second longitudinal fold wherein two complete longitudinal-fold units with a separate drive for each are arranged in superposition. The part of the product stream processed in the upper longitudinal-fold unit is led via a conveyor belt system to a fan wheel arranged below the lower longitudinalfold unit. Leading the longitudinally folded products below the upper longitudinal-fold unit requires a long stretch of conveyor belts which has to lead around the lower longitudinal-fold unit, in order to ensure the conveyance of the products into a fan wheel provided for both longitudinal-fold units. Therefore.. this train of conveyor belts necessitates tensioning devices, so that any elongations of the belts caused by speed variations can be compensated. Consequently, the construction of this longitudinal-fold device is rather extensive in width, even though the two longitudinal-fold units are arranged in superposition. Considering, that the drive of the longitudinal-fold blade is not illustrated. the space requirement for this device is even greater. The arms, being pivotally mounted at the respective folding table. cause the folding blades fastened to said arms to describe a circular arc while they are dipped into the gap between the folding rollers. Thereby, it can occur that the second longitudinal fold is not precisely formed in place; this can be a reason for customer complaints.

Therefore, it is the object of this invention to improve a device for longitudinally folding signatures in such a way that, while it uses up less construction space, it ensures a longitudinal fold to be formed precisely in place, even at highest production speeds.

According to the invention, this object is solved by a longitudinal-fold device having the following features: a continuous signature stream is split up behind a signature-carrying cylinder to be transportet in different conveyor belt systems; to the conveyor belt systems there is assigned a respective further conveying system; between two folding tables there is arranged a folding blade having a drive; and the folding blade cooperates alternatingly with folding elements disposed above the drive and with folding elements disposed below the drive.

This solution offers the advantage that with a folding blade operating between two folding tables a second folding blade and a second drive can be eliminated., thereby enabling a reduction in construction space and cost. Since with the device according to the invention longitudinal folding takes place alternatingly, considerably more time is available for the individual performance of a fold. The time period available for the slow-down of the signature stream, for the feed-in and the pull- through of the individual signature is a considerably longer one, i.e. twice as long; the speed of impact of the folding blade on the signature can be cut in half. The folding blade, now, does not fold only with its downward movement but with its downward and upward movement. Thus, two signatures in place of one are folded per working cycle of the device for longitudinally folding according to the invention. This will be the basis for doubling production s p e e d.

3 in another embodiment of the invention the folding blade is formed with two cutting edges at its ends. These cutting edges move onto the folding tables above and below the drive. Furthermore, the folding blade is urged by gear wheels and other drive elements in the drive mechanism to perform a rectilinear, vertical stroke. Thereby,,an optimal folding accuracy, subject to a tolerance of only 0.5 mm, can be achieved. Furthermore, the folding elements are designed as folding rollers which serve as deviation stations for the conveying belts of conveying systems. This ensures a reliable signature guidance at highest production speeds as well as a timed signature guidance into the adjoining delivery devices. The paths of the conveying systems lead to the circumference of the fan wheel assigned to both conveying systems, so that by insertion.of the individual signatures into successive fan wheel pockets a continuous delivery of the product stream is achieved.

On the signature-carrying cylinder there is arranged a controllable deflection tongue dividing and directing the continuous signature stream into an upper and a lower conveyor belt system. Also, the signatures in the upper conveyor belt system pass a signature deflection unit positioned in front of the folding elements. Thereby, the signatures in the upper conveyor belt system can be longitudinally folded in the same manner as those in the lower conveyor belt system. The device for longitudinal folding according to the invention, thus, is especially adapted to production in rotary printing presses with single-size plate cylinder circumferences.

According to another feature of the invention there is arranged, in the infeed area of the lower conveyor belt system, an infeed roll having an enlarged diameter, said infeed roll serving to eliminate effects of relative shifts longitudinal fold is performed therein. Thereby, optimal folding accuracy is achieved, since the leafs of the signature have come to lie in exact superposition. The Lengths and the conveying speed of the conveying belts is calculated such that the full length of a respective signature faces the full length of a respective cutting edge of the folding blade before it impacts on the signature.

The present invention wilt be best understood from the following description of specific embodiments when read in connection with the accompanying drawings., in which

Fig. 1 is a side view of the device for longitudinal folding, including signature-carrying cylinders arranged in front of the device; Fig. 2 is a view of the device in parallel with the folding blade and of the paths of the conveyor belts of the conveying systems.

Fig. 1 shows the device for longitudinal folding, with the signaturecarrying cylinders 1, 2 and 3 being arranged in front of said device for carrying out the cross-fold. A collecting cylinder 1 is followed by a jaw cylinder 2 which is provided with circular grooves 4 as well as with folding blades 5 and folding jaws 6 on its outer cylindrical surface. Behind the jaw cylinder 2 there is arranged a gripper cylinder 3 which also is provided with circular grooves, and signature-stripping tongues dip into said grooves, thereby effecting the entry of the signatures into a lower conveyor belt system. Also, the gripper cylinder 3 comprises folding jaws 6, grippers 7, gripper bars 8 and gripper shafts 9, said grippers 7 cooperating with said gripper bars 8 while being actuated through said gripper shafts 9. In order to prevent collisions, the heads of the grippers 7 move in the circular grooves of the adjacent folding jaw cylinder 2.

The take-off of the cross-folded signatures from the circumference of the gripper cylinder 3 takes place through a time-controlled deflection tongue 10 which directs the signatures into an upper conveyor belt system 11 and via a stripping tongue into a lower conveyor belt system 21. The upper conveyor belt system consists of a top belt 12 and a bottom belt 13 which, respectively, pass over deflecting rollers 14. Parallel to the transport direction of the signatures there are provided,, above the top belt 12, folding rollers 15 below which there extends an upper folding table 16. A folding blade 18 is disposed below the bottom belt 13 in the area of a lower folding table 25. Through gear whee ls 19 and further drive elements in a drive mechanism 20 the folding blade 18 is urged to perform a very precise vertical up-and-down movement; in place of a spur wheel between the gear wheels 19 there could also be used a cogged belt drive.

In the upper conveyor belt system 11 there is arranged, in front of the folding elements 15, 16, a signature turning unit 17 in which the signatures lead by the time-controlled deflection tongue 10 from the gripper cylinder 3 into the upper conveyor belt system 11 are turned. Thereby,, the signatures in the upper conveyor belt system 11 and the signatures in the lower conveyor belt system 21 can be folded in the same manner. With production in machines having single-size plate cylinders the signature turning unit 17 is activated, and with production in machines having double-size plate cylinders the signature turning unit 17 can be switched of f.

Above the upper conveyor belt system 11 there is arranged a conveying system 28 in which the signatures being transported 6 - in the upper conveyor belt system and subsequently being longitudinally folded are transported into the fan wheel 27.

When the time-controlled deflection tongue 10 is being disengaged from the circumference of the gripper cylinder 3, the signature on the gripper circumference following next is led by the strippers into the lower conveyor belt system 21. In order to prevent relative movements of individual leafs in the multi-leaf, cross-folded signatures, there is provided, in the entry region of the conveyor belt system 21 an infeed roll 26 which prevents an abrupt deflection of the signatures. The lower conveyor belt system 21 comprises a top belt 22 and a bottom belt 23, and folding rollers 24 and a folding table are located therebelow. Besides, the folding rollers 15 of the upper conveyor belt system 11 and the folding rollers 24 of the lower conveyor belt system 21 also serve as deflectors for conveying belts of the conveying systems 28 and 31 which transport the signatures to the pockets of the fan wheel 27.

Fig. 2 shows the device for longitudinally folding as viewed in parallel to the folding blade, so that the path of the conveyor belt trains becomes apparent.

The folding blade 18, having cutting edges at its ends, is cyclically moved up and down above the compact drive 20; thus, two signatures are folded per moving cycle, one being present on the upper folding table 16 and one being present on the lower folding table 24. The strictly straight-lined up and down movement of the folding blade 18 ensures that the cutting edges of the folding blade impact on the signatures in full length, so that the folding spine is formed simultaneously over the entire length of the signature between the upper folding rollers 15 as well as the signature between the lower folding rollers 24. The conveying speed and the conveying path of the signatures in the upper and tower conveyor belt systems 11 and 21 are calculated in such a way that the signatures in their entire lengths are present above the respective recess of the respective folding tables 16 and 25 in time before the impact of the respective cutting edges on the respective signatures. An adjustment of the phase relationship of the folding blade 18 with respect to the signatures can be performed at the drive 20.

The signatures longitudinally folded on the upper folding table 16 are gripped by the two folding rollers 15, and the folding spine of the signatures is subsequently formed between them. The conveyor belts 29 of the upper conveying system 28 transport the signatures provided with the second longitudinal fold into the pockets 33 of the fan wheel 27. The precisely positioned transport of the signatures in the upper conveying system 28 is aided by the provision a large-diameter roller 30 in their conveying path. This roller 30 ensures that multipleleaf signatures are transported and deflected without their leafs shifting with respect to one another. The deviation of the conveyor belts 29 takes place - aside from the roller 30 - essentially through idler rollers 14 on which the conveyor belts 29 rotate. Approximately the same conveying speed exists in the upper and in the lower conveying systems 28 and 31. Thereby can be achieved a cyclic insertion of the signatures into the individual pockets 33 of the fan wheel 27. In the lower conveying system 31 the signatures are transported by the conveyor belts 32 into the fan wheel pockets 33 after they have passed through the gap between the lower folding rollers 24.

Since in this manner each pocket 33 of the fan wheel 27 has been provided with a signature, a continuous shingled-stream delivery on the delivery belt 35 can now be realized. A doubling of the production output can thus be achieved by dividing a continuous signature stream for transport in two conveyor belt systems 11, 21 and with a folding blade 18 acting on both sides. There is more time available for infeeding and passing the individual signature to be folded through the respective folding rollers 15 and 24. Furthermore, the speed of impact of the respective cutting edge of the folding blade 18 on the individual signature prevailing in conventional systems for the second longitudinal fold can be lowered to facilitate thin types of paper.

Thus, the potential for doubling the production speed of a rotary printing press disposed in front of a folding apparatus I i es in the uti I izati on the complete stroke motion of the folding blade - i.e., one fold with a down-stroke and one fold with an up-stroke -, as longer time spans of signature processing in the device for longitudinally folding according to the invention, in turn, enable an increase in rotary speed of the press.

It will of course be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.

9

Claims

CLAIMS:

1. A device for longitudinally folding signatures, comprising a signaturecarrying cylinder, means to split up a continuous signature stream behind the signature-carrying cylinder so that the signatures are transported in two different conveyor belt systems, a respective further conveying system assigned to each of said conveyor belt systems, two folding tables between which there is arranged a folding blade, a drive for the blade, and said folding blade co-operating alternatingly with folding elements disposed above said drive and with folding elements disposed below said drive.

2. A device according to claim 1, wherein the ends of the folding blade are formed with cutting edges.

3. A device according to claim 1 or 2, wherein the drive urges the folding blade to perform a straight-lined vertical up-and-down movement through gear wheels and further drive elements.

4. A device according to claim 1, 2 or 3, wherein the folding elements are designed as folding rollers which serve as deviation stations for conveyor belts of the further conveying systems.

5. A device according to claim 4, wherein the transport paths of the further conveying systems lead to the circumference of a mutual fan wheel.

6. A device according to any one of claims 1-5, wherein said means to split the signature stream comprises a controllable deflection tongue on the s ignature- carrying cylinder which divides the stream to an upper conveyor belt system and a lower conveyor belt system.

7. A device according to claim 6, wherein the signatures in the upper conveyor belt system pass a signature-turning unit disposed in front of the folding tables.

8. A device according to claim 6 or 7, wherein, in the entry region of the lower conveyor belt system, there is an 5 infeed roll having an enlarged diameter.

9. A device according to any one of claims 3-8 when dependent on claim 2, wherein the length and the conveying speed of the conveyor belts is such that the full length of a respective signature faces the full length of a respective cutting edge of the folding blade before the impact of said folding blade on said signature takes place.

10. A device for longitudinally folding signatures, substantially as hereinbefore described with reference to the accompanying drawings.