GB2106478A - Sheet folding apparatus - Google Patents

Abstract

Sheet folding apparatus comprises folding rollers (4, 5) and blade shafts which are arranged in pairs to move a sheet to be folded and are mounted to be displaceable in respect of their spacing each from the other. Any desired folding roller or blade shaft, preferably a folding roller disposed lowermost, is arranged firmly in the apparatus frame (1) and connected directly with a drive (23). A gear transmission (7) is arranged in a closed casing (8) and provides output shafts (10, 11) for the displaceable folding rollers (4, 5) and blade shafts; preferably the folding gap (14) is settable by vertical displacement of roller (4). <IMAGE>

Description

SPECIFICATION Sheet folding apparatus The present invention relates to sheet folding apparatus and has particular reference to a drive for folding rollers and blade shafts of a folding mechanism.

It is known to firmly mount in the machine frame a driven folding roller of a roller pair arranged uppermost in the folding mechanism and to mount the remaining folding rollers of the folding mechanism to be pivotable at levers and pressable by springs one against the other in such a manner that toothed gear wheels thereof mesh with a toothed gear wheel of the driven folding roller either directly or through the toothed gear wheel of a pivotably mounted roller. In that case, individual levers are so constructed that the spacing between the pivot point of the lever in the machine frame and the rotational centre of the folding roller is settable or variable.

It is disadvantageous in this case that a roller of the uppermost pair must be selected as driven roller firmly mounted in the machine frame because the folding rollers, driven by toothed gear wheels and mounted in levers, must be driven according to a certain sequence. This measure is obliged by the influence of the force component which is derived from the circumferential force through the engagement angle of the gear wheels and which, during the starting and running, acts as a constant, uncontrollable relief force on the folding roller spring.In the case of a folding roller pair disposed beiow in the known staircase-like stepping of the folding roller pairs, if one roller thereof were to be chosen to be the firmly mounted and driven roller, the force-locking in the folding roller system would be cancelled sporadically and the folding gap would change, with the consequence of an inaccurate folding.

Counteracting measures, for example reinforcement of the folding roller springs, would lead to higher material expenditures and greater wear of the folding rollers and make the operation more difficult.

It is also disadvantageous in this known drive arrangement for rollers that the gear wheels in consequence of their variable axial spacing do not mesh with each other in the rolling circle and can even come out of interengagement in the case of stoppages through excessively thick products to be folded. An appreciable generation of noise and substantial wear of the gears wheels is connected therewith. Gear wheels not meshing exactly in the rolling circle can also exert an influence on the accuracy of folding when greater play is present. A further disadvantage is in that a high maintenance effort is required for lubrication of the drives.

It is also known to drive the gear wheels of the individual folding rollers, which are pivotably mounted in the machine frame by means of a lever, through a gear wheel which is mounted in a lever pivot point fast with the frame and in its turn is driven with the remaining central wheels fast with the frame. In this drive arrangement, the axial spacing of the meshing gear wheels is always constant.

It is disadvantageous in this case that the required effort is inordinately high and the noise generation due to the multiplicity of meshing gear wheels is practically the same as for the simpler arrangement with variable axial spacing of the gear wheels. The multiplicity of gear wheels also requires continuous maintenance and lubrication.

It is also known, according to DD-PS 114 385, to mount the drive wheel of each folding roller overhung locally fixed, all displaceable folding rollers being coupled with respectively associated drive wheel through a respective equalising coupling.

In this construction, the gear wheels of each folding roller pair always mesh in the rolling circle and the changing axial spacing of the folding rollers in certain regions has no influence on the correct engagement of the gear wheels. It is particularly disadvantageous in this construction that the manufacturing effort is very high, the manufacture of the overhung-mounted drive wheels entails problems and, due to the sliding drive transmission onto the equalising coupling and the constantly present paper dust, the gear wheels are subject to considerable wear.

There is accordingly a need for a folding mechanism drive which increases the utility value of the folding apparatus and reduces wear and maintenance effort. Preferably, such a drive should require fewer gear wheels than necessary in the case of the known drives and the drive wheels of each roller and shaft of the folding mechanism should always mesh in the rolling circle independently of the size of the set folding gap, while the life duration of the wheels should be substantially increased and the noises emanating therefrom reduced.

According to the invention, there is provided sheet folding apparatus comprising a plurality of sheet folding rollers and blade shafts arranged in pairs and mounted to be relatively displaceable to vary the spacing thereof, any one of said plurality of rollers and shafts being mounted in a fixed position in frame means of the apparatus, drive means directly connected to said one roller or shaft, and transmission means drivingly coupled to the individual rollers and shafts and disposed in a closed casing.

In a preferred embodiment, the rollers and shafts are associated in pairs and are mounted to be displaceable in respect of their spacing each from the other, wherein each roller pair in engagement one with the other through toothed wheels and each roller and shaft is driven by a drive device. A roller or shaft selected as desired is each time structured as an element firmly mounted in the apparatus frame and driving the folding mechanism. Preferably, the selected roller or shaft is a folding roller of a lowermost roller pair. All other folding rollers may be mounted to be pivotable against spring force.A gear transmission means for the drive of the individual folding rollers and blade shafts is accommodated in an enclosed casing and the output shafts of the transmission means are connected through flexible elements, preferably respective articulated shafts, with the individual folding rollers or blade shafts. The casing is fastened to the frame of the apparatus through components, for example silent bushes, which damp oscillations and interrupt sound conducted by solids.

Individual toothed gear wheels for the drive of the folding rollers or blade shafts may be firmly arranged in the casing, that is to say the displacement of the rollers for setting of the required folding gap does not produce a positional change of the associated gear wheels. It is thus ensured that the gear wheels always mesh one with the other in due order.

This setting of the folding gap, which is to be adapted to the thickness of the sheet to be folded, requires a horizontal compensation for the vertical change in spacing of the folding rollers. For this purpose, the aforesaid articulated shafts may be constructed to be telescopic or the output shafts arranged in the gear casing may be splined. When other flexible elements are used for the drive transmission, this compensation can also result from the inherent flexibility of the element.

Such a construction of the folding roller drive necessitates use of fewer gear wheels than before, ensures a longer life for the gear wheels, and reduces the amount of noise that is generated.

An embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a schematic partly sectional elevation of a folding mechanism drive system in folding apparatus according to the said embodiments; Fig. 2 is a side elevation of folding rollers pivotably mounted on levers and of a folding roller mounted fast in a frame of the apparatus; Fig. 3 is a side elevation of a known drive component in which toothed gear wheels, influenced by the paper thickness to be folded, mesh externally of their rolling circle, and Fig. 4 is a side elevation of folding rollers and blade shafts of the folding mechanism of the apparatus of Fig. 1, showing the displaceability of the rollers and shafts.

Referring now to the drawings there is shown part of sheet folding apparatus comprising a plurality of folding rollers and blade shafts mounted in a frame 1 of the apparatus, the rollers and shafts being arranged as shown in Fig. 4. The lowermost folding roller 1 7 is firmly mounted in the frame 1 and connected directly with a folding mechanism drive 23. All other displaceable folding rollers 2, 4, 5, 1 5 and 1 6 and the blade shafts 18 and 1 9 are fastened in the frame 1 at a variable spacing from the associated counter-roller through levers 6 (Figs. 1 and 2) pivotable against the force of a spring 3.

A gear transmission 7 for the drive of the individual displaceable folding rollers and blade shafts is accommodated in a closed casing 8, which is connected to the frame 1 through elements 9 damping oscillation and interrupting sound conducted by solids. Output shafts 10 and 11 of the transmission 8 are connected through articulated shafts 12 and 1 3 with the rollers 4 and 5 and thus make possible an uncomplicated setting of a folding gap 14 according to the thickness of a paper sheet to be folded without requiring a change in the position of toothed gear wheels 20 and 21 connected to the rollers.

The setting of the gap 14 takes place, as indicated in Fig. 1, through vertical displacement of the roller 4. The travel change in that case taking place in horizontal direction is made possible by the construction of the articulated shafts 12 and 1 3 as telescopic shafts or construction of the output shafts 10 and 11 as, for example, splined shafts.

The change in spacing, required by the setting of the gap 14, of the displaceable folding rollers and blade shafts takes place without influencing the interengagement of the gear wheels associated with the individual rollers and shafts. It is thereby ensured that, for example, the gear wheels 20 and 21 always run in the rolling circle without displacement relative to each other.

At the same time, the arrangement of the transmission 7 in a closed casing 8 creates the prerequisite that the transmission can run in an oil bath and that a constant uniform lubrication of the transmission is achieved as a result. Through the use of seals 22, escape of the lubricant is avoided and pollution of the rollers 4 and 5 is avoided.

The running noise of the gear wheels 20 and 21 and of the other gear wheels (not shown) is minimized by virtue of the facts that constant meshing of the gear wheels in the rolling circle is ensured and that the transmission as a whole is accommodated in a casing 8 which is connected with the frame 1 through elements 9 that damp oscillation and interrupt conduction of sound.

Claims (8)

1. Sheet folding apparatus comprising a plurality of sheet folding rollers and blade shafts arranged in pairs and mounted to be relatively displaceable to vary the spacing thereof, any one of said plurality of rollers and shafts being mounted in a fixed position in frame means of the apparatus, drive means directly connected to said one roller or shaft, and transmission means drivingly coupled to the individual rollers and shafts and disposed in a closed casing.

2. Apparatus as claimed in claim 1, wherein said one roller or shaft is a lowermost one of said rollers and shafts.

3. Apparatus as claimed in either claim 1 or claim 2, comprising a respective flexible coupling element coupling each displaceably mounted one of the rollers and shafts to the transmission means, the transmission means being drivably coupled to the drive means.

4. Apparatus as claimed in claim 3, wherein each of the coupling elements comprises an articulated shaft.

5. Apparatus as claimed in claim 4, wherein each of the articulated shafts is telescopic and is coupled to a respective output shaft of the transmission means, each output shaft being keyed to a respective gear wheel.

6. Apparatus as claimed in claim 4, wherein each of the articulated shafts is slidably coupled to a respective output shaft of the transmission means by splined coupling means.

7. Apparatus as claimed in any one of the preceding claims, wherein the casing is connected to the frame means by sound and vibration damping elements.

8. Sheet folding apparatus substantially as hereinbefore described with reference to the accompanying drawings.