Device for reducing the emission of noise in buckle folding machines

A device for reducing the emission of noise in buckle folding units provided with noise control enclosures, comprising a noise control hood 5 essentially completely enclosing the upper 41 and lower folding pockets 42 and the folding rolls 7, said noise control hood 5 being at least partially slidingly displaceable, tiltable and/or removable and being provided with a slot for the passage of the sheet in the associated hood section, which slot is aligned with the nip of the pair of intake and discharge rolls, respectively, is improved by further reducing the noise emission in the sheet discharge area without influencing dependable function and easy access to this area. This is obtained by the fact that the hood section associated with the pair of discharge rolls 71, 72 comprises a cover plate 10 having a vertical first section 12 secured to the hood and a second section 11 held on the first section 12 pivotably between an inclined closed position adjoining to the hood and an opened position above the folding rolls 7, wherein the longitudinal edges, being parallel to the roll axes, of the discharge slot 15 provided in the vertical section 12 are arranged such as to form noise emission sealing sites in cooperation with the peripheral surfaces of the pair of discharge rolls 71, 72.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a device for reducing the emission of 
noise in buckle folding units provided with sound-proofing enclosures, 
comprising a noise control hood essentially completely enclosing the upper 
and lower folding pockets and the folding rolls, said noise control hood 
being at least partially slidingly displaceable, pivotable and/or 
removable and being provided with a slot for the passage of the sheet in 
the associated hood section, which slot is aligned with the nip of the 
pair of intake and discharge rolls, respectively. 
2. Brief Description of the Prior Art 
It has already been known to reduce the noise emitted by buckle folding 
machines by enclosing the whole folding unit or the noise-emitting part 
thereof, particularly the upper and lower folding pockets, in a noise 
control hood which, in order to make its interior accessible, is provided 
with silding, tilting and/or removable parts and which is lined with 
noise-absorbing and/or noise-reflecting material. However, it is necessary 
to provide in the associated hood section a slot in alignment with the nip 
of the intake and discharge rolls, respectively (East German Pat. No. 
118,588; "Der Polygraph", Part 20, 1978, pages 1705, 1706). 
In view of the fact that trouble frequently arises in the discharge section 
of the folding unit, such trouble requiring direct access for correction, 
it has been customary to provide a relatively large aperture on the 
discharge end. Attempts to dispose part of the noise control hood at the 
smallest possible distance from the last folding rolls to be passed by the 
sheets have shown that this remedy makes it very difficult to install and 
adjust the knives on the knife shafts which are in many cases disposed 
downstream of the last pair of folding rolls. Particularly in cases in 
which a plurality of buckle folding units are arranged in series or in 
which a buckle folding unit is combined with a plurality of knife folding 
units disposed downstream thereof it may become impossible to dismantle 
the knife shafts and to remove them from the machine. Also the removal of 
sheet material which has become jammed in the machine is difficult because 
such material is not readily accessible. 
This disadvantage is found also in the case of a well-known buckle folding 
machine (West German provisionally laid out print DE-OS No. 23 61 803), 
the sheet deflectors of which are held to absorb sound conducted through 
solids. As the noise can be transferred by the rotation of the folding 
rolls, particularly by the little grooves thereof, sound absorbing or 
sound dampening bodies are provided between the last two folding rolls and 
a pair of further shafts which may be installed stationarily. The 
discharge slot defined by these bodies converges in the direction toward 
the further shafts. An integration of these bodies in a noise emission 
control hood is not shown. 
OBJECT OF THE INVENTION 
Therefore, it is an object of this invention to modify the device of the 
type described initially in such a manner that it is possible to attain in 
the area of the discharge slot an enhanced reduction in the emission of 
noise of the folding unit with very simple means, maintaining the 
possibility of easy access to the sheet discharge area. 
SUMMARY OF THE INVENTION 
Taking a device of the type indicated as a starting point, this object is 
attained according to the invention in that the hood section associated 
with the pair of discharge rolls comprises a cover plate having a vertical 
first section secured to the hood and a second section held on the first 
section pivotably between an inclined closed position adjoining to the 
hood and an opened oposition above the folding rolls, wherein the 
longitudinal edges, being parallel to the roll axes, of the slot provided 
in the vertical section are arranged such as to form noise emission 
sealing sites in cooperation with the peripheral surfaces of the pair of 
discharge rolls. 
The device according to the invention has the advantage that the noise 
emission of the known folding units can be reduced by 3 dB or more in 
addition to the noise control provided by the noise control hood. Although 
noise emission sealing sites are provided, the dependable function of the 
folding rolls is permitted even under the viewpoint of thermal expansion 
and of the change of the position of the folding rolls caused by different 
sheet thicknesses. Further the servicing and trouble correcting operations 
can be performed on the machine parts at the discharge end of the folding 
machine without any impediment. Usually the sections of the cover plate 
are lined with a noise-absorbing and/or noise reflecting material. Since 
the pivotable second section can be tilted, the knife shafts remain 
accessible from above so that, with the folding pockets withdrawn or 
removed, the knife shafts may be easily adjusted or dismantled in an 
upward direction and that trouble correcting operations can be easily 
performed even in cases in which a plurality of buckle folding units are 
arranged in series or combined with folding knife units. Moreover, the 
movable section, when tilted out of its closed position, protects the 
folding rolls from damage, particularly during removal of the knife shafts 
carrying cutting, perforating or scoring tools. Moreover, the operating 
personnel is protected from the drawing-in slots of the folding roll in 
the event the machine is inadvertently started during assembly operations. 
As regards the provision of noise emission seals of the type just 
described, it has been found convenient to provide additional guide 
members on the upper and/or lower edge of the discharge slot. Such guide 
members end immediately adjacent to the pair of rolls associated 
therewith. This means that the end faces of the guide members which define 
the discharge slot for the folded sheets are disposed at so small a 
distance from the last pair of folding rolls that the functon of the pair 
of rolls is not jeopardized, with the distance, however, being so narrow 
that the desired noise emission site or line or surface is provided.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
The buckle folding unit 1 shown in FIG. 1 is supplied with sheets to be 
folded via an aligning table 2 in the conveying direction indicated by 
arrow 3. The buckle folding machine includes upper folding pockets 41 and 
lower folding pockets 42 which are provided with stop members and which 
are almost completely enclosed in a noise control hood 5, with the bottom 
52 of the upper part of noise control hood 5 being provided with a 
pivotable noise control flap 55 disposed in the vicinity of the folding 
rolls 7. The cover 51 and the bottom 52 of the upper part of noise control 
hood 5 are adapted to be slidably displaced or tilted and/or removed. The 
lower part of noise control hood 5 comprises an upper section 53 and a 
lower section 54, the two sections enclosing the lower folding pocket 42 
and being adapted to be opened partially or completely. Disposed between 
lower section 54 and the folding rolls 7 is a cross member 6 in the form 
of an angular section. The last folding roll pair 71, 72 transfers the 
folded sheets to a knife shaft pair 81, 82 downstream of which (referring 
to arrow 3 indicating the conveying direction) a ribbon roll 9 is 
disposed. A cover plate 10 serving to reduce the emission of noise is 
disposed on the discharge side of the folding rolls 7. 
As shown in FIG. 2, cover plate 10 is provided with a base portion 17 by 
means of which the cover plate is secured to the angle section transverse 
member 6. In addition, cover plate 10 comprises, as an integral part of 
base section 17, an essentially vertically disposed section 12 which, on 
the side facing the folding unit, is provided with a lining 13 consisting 
of a noise absorbing and/or reflecting material. The vertically extending 
section 12 of cover plate 10 is provided with a discharge slot 15 for the 
folding sheets, slot 15 being disposed in such a manner that its center 
line is essentially aligned with the gap defined by conveyor rolls 71 and 
72, these rolls being disposed at the smallest possible distance from the 
noise absorbing and/or noise reflecting lining 13 of cover plate section 
12 as is compatible with an unimpeded function of folding rolls 71 and 72 
with due consideration being given to expansion phenomena resulting from 
the structure of the machine and caused by thermal effects as well as to 
axis displacements resulting from the passage of sheets of varying 
thickness. Between the longitudinal edges parallel to the folding roll 
axes of the discharge slot 15 and the peripheral faces of the folding 
rolls 71 and 72 noise emission sealing sites are formed which serve to 
provide the desired additional sound-proofing of 3 dB and more. The height 
of discharge slot 15 is smaller than the vertical spacing of the folding 
roll axes, but it is sufficient to ensure trouble-free passage of the 
folded sheets toward knife shafts 81 and 82. 
Connected to the vertically extending section 12 of cover plate 10 by means 
of a hinge 14 is an inclined section 11 of the cover plate which 
co-operates at 16 with the bottom 52 of the upper section of noise control 
hood 5 and which is also provided with a lining 13 consisting of a noise 
absorbing and/or noise reflecting material. After the folding pockets 41 
have been withdrawn or removed, the inclined section 11 may be tilted in 
the direction of arrow 20 towards the folding rolls 7 so as to provide 
free access to knife shafts 81 and 82 with section 11 at the same time 
constituting a cover protecting the folding rolls 7. 
In the embodiment shown in FIG. 3, the height of discharge slot 15 is 
slightly smaller than twice the distance between the axes of the 
sheet-discharging folding rolls 71, 72. The longitudinal edges defining 
the discharge slot 15 of the vertically extending section 12 of cover 
plate 10 are disposed in the direct vicinity of the peripheral surfaces of 
said rolls so as to provide the desired additional noise control effect 
described earlier. 
FIGS. 4 to 8 show a number of further embodiments illustrating the large 
number of possibilities of employing guide members 21 and 22 in order to 
dispose the above-mentioned noise emission control seals in the desired 
manner and/or to reduce the tendency of the folded sheets to deviate from 
the desired direction of feed as well as to limit elastic flexing of the 
folded sheets. The narrowing of the discharge slot resulting from the 
converging arrangement of guide members 21 and 22 also tends to reduce the 
emission of noise. 
In the embodiment shown in FIG. 4, the guide members 21 and 22 are disposed 
on the associated longitudinal edge of the discharge slot 15 in such a 
manner that they project beyond the discharge slot on both sides thereof 
and that they converge in the direction of sheet travel indicated by arrow 
3. The edges of the guide members 21, 22 facing the folding rolls 71, 72 
are disposed in the immediate vicinity of the peripheral surfaces of these 
rolls, this arrangement resulting in the formation of noise emission seals 
without the function of rolls 71, 72 being impaired. The other edges of 
the guide members 21, 22 are disposed in the immediate vicinity of knife 
rolls 81, 82. 
In the embodiment shown in FIG. 5, the guide members 21, 22 resembling 
those emloyed in the embodiment of FIG. 5 are displaced in the direction 
of sheet travel (arrow 3) to such an extent that their front edges are 
aligned with the surface of the vertical cover plate section 12 facing 
folding rolls 71, 72. In this embodiment, the noise emisson seals proper 
are disposed between the peripheral surfaces of rolls 71, 72 on the one 
hand and the longitudinal edges of the discharge slot 15 in the area of 
the vertical cover plate section 12 on the other hand. 
In the embodiment shown in FIG. 6, the guide members 21, 22 extend 
convergingly towards the discharge slot between folding rolls 71, 72, the 
result being that the noise emission sealing zones are disposed at a 
smaller distance from the center line of discharge slot 15. 
In the embodiment shown in FIG. 7, the guide members 21, 22 are formed by 
angulated terminal portions on the side of the discharge slot 15 of the 
vertical section 12 of cover plate 10, the folded edges being disposed in 
the immediate vicinity of folding rolls 71, 72 for the purpose of forming 
a plurality of noise emission seals. 
In the embodiment shown in FIG. 8, only the lower longitudinal edge of 
discharge slot 15 is provided with a guide member 21, the end faces of 
which are disposed in the immediate vicinity of lower folding roll 21 and 
lower knife shaft 81, respectively. The upper edge is formed by a curved 
portion of the cover plate section 12 which follows the curvature of the 
peripheral surface of upper folding roll 72 for the purpose of 
constituting a noise emission sealing surface.