This invention relates to a folding machine for folding sheet material in concertina fashion according to the first portion of claim 1.
Italian Patent specification No. 906.210 and 911.967 discloses such folding machines.
The Italian Patent No. 906.210 (=GB-A-1349 558) relates to a folding machine comprising three contiguous rollers, the central lower roller being simultaneously in constant contact with both the two lateral upper rollers. All the rollers rotate in both the directions, alternatively, in order to produce zig-zag or concertina-like folds in a paper material; the central roller cooperates alternatively with one of the two lateral rollers, acting as a folding roller.
The Italian Patent No. 911.967 relates to a folding machine which comprises, as the above mentioned machine, three rollers.
The central lower roller is on contact, alternatively, with only one of the two upper rollers in turn and for this reason the lower roller is moved towards the right and towards the left, alternately.
It is also known from the specification DE-A-2227582 Meteor a zig-zag paper folder in which the folding elements are constituted by two pairs of rollers 4―6 and 3-5; the rollers 5 and 6 must be able to be moved away from the rollers 3 and 4 in order to receive between each pair a plurality of layers of folded sheets. Two sets of belts, interposed to each other, are mounted on said rollers to retain the paper; they have a rectilinear speed equal to the peripheral speed of the folding rollers which support them.
EP-A-0037650 HARPER provides two pairs of folding rolls 5-7 and 4―6. The incoming papers, which rests on a stationary plate 14, is addressed, by a swinging or rotating deflecting element 16 or 13, towards the right or towards the left. The present machine is intended to enable sheet material such as paper to be folded in concertina fashion whilst being responsive to different kinds and thickness of paper sheets by utilizing the capabilities of electronic microprocessors.
For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:
The general construction of the machine will first be described.
A horizontal table TA is provided for feeding longitudinal sheets FO (Figure 4) of material such as paper to be concertina folded to an inlet location and a feed means is provided in the form of a unidirectionally driving inlet roller RM1 co-operating with associated idler rollers (or balls) RF' and RF2, these rollers serving to feed the sheets to an entry path or track CE.
NA1 and NA2 are sets of strongly tensioned endless bands extending around driving rollers RM2 and RM3 and around idler rollers RF2 and RF3 respectively, these bands being arranged at the folding station according to a specular symmetry about the plane of the intended direction of feed of the sheet material along the inlet path CE. Respective working runs of the bands NA1 and NA2 are arranged tangentially with respect to idler rollers RF4 and RF5, these rollers RF4 and RF5 having respective tapered portions PE1 and PE2 and toroidal guide grooves SC1 and SC2 to accommodate endless belts CN wound around a pair of lower rollers RM4 and RF6. The roller RM4 is driven and its direction of rotation can be reversed and the roller RF6 is an idler roller. Accordingly, the rollers RM2 and RM3 drive respectively the rollers RF4 and RF5 via the bands NA1 and NA2.
Another roller RO is arranged to be driven in a direction which depends on the direction of rotation of the driving rollers RM2, RM3 and RM4 and is shiftable in said plane from an upper position (Figure 1) at the beginning of the operating cycle in order to direct the sheet material towards the band NA and a lower position, which is achieved after the beginning of the cycle, whilst continuing to rotate in the same direction as the roller RM4, in order not to hinder the formation of folds in the sheet material (Figures 2 and 3).
Detecting means in the form of photoelectric cells CF1 and CF2 control the directions of rotation of the driving rollers RM2, RM3 and RM4. In addition, a photoelectric cell CF3 is located adjacent to the entry path CE.
In operation, starting from the Figure 1 position, the driving roller RM' feeds the sheet FO towards the entry path CE until the sheet drops to the folding station to meet the rotating roller RO (which is in its upper position) so that the sheet is directed between the lower, working run of the band NA and the roller RF5 and consequently the sheet is positively carried towards the photoelectric cell CF'. As soon as the leading edge of the sheet breaks the light beam directed towards the photoelectric cell, a servocontrol causes the direction of rotation of the driving rollers RM3 and RM4 to be reversed, whilst the driving roller RM1 continues to rotate always in the same initial direction. As can be seen from Figure 2, this has the effect of drawing the sheet material such as paper to form a loop to provide a first fold therein. The photoelectric cell CF3 mounted in the -entry path CE is instrumental in initiating the rotation of the rollers RM2, RM3, RM4 and RO.
The same cycle is then repeated but in the opposite direction as soon as the next leading (folded) edge of the sheet reaches the photoelectric cell CF2. The folding cycles are repeated till the exhaustion of the length of sheet matrerial being fed in, so that it becomes folded in concertina fashion (Figure 4). Provision may be made for microprocessors co-operating with the photoelectric cells CF', CF2 in order to survey and regulate the folding of the sheets. Comparing Figures 1 and 2, after the first fold has been made, the roller RO is shifted into its lower position and remains in that position as a result of a control impulse given by the photoelectric cell F4. The roller RO is driven in synchronism with the roller RM4 and this achieves a rolling support for the sheet to be folded.
It will be appreciated that the present folding machine does not have stationary channels between which the pack of folded sheet material can slide during the folding operation as with a known machine; on the contrary, the "channels" are movable and consist of the belts CN and bands NA', NA2 which accompany the material during the reciprocating movement whereby movement of the material is not hindered thereby inhibiting consequent jamming of the machine.
Furthermore, the utilisation of one or more bands NA', NA2 in lieu of a rigid roller in order to carry out the deflection of the fold against the rollers RF4, RF5 permits a better performance to be obtained than that obtained with known folding machines, since the surfaces of the bands between the rollers can yield and permit the passage of folded paper packets presenting a significant thickness. The choice of a second folding roller as provided in known folding machines for small sheets would force the second roller to lose its initial parallelism if a sheet is folded which presents a width less than that of the second roller. Consequently the pressure upon the paper would not be uniform and the operation would not be correct. In a preferred embodiment of the present machine, it is possible to fold sheets having a number of different lengths and widths up to 10 meters.
Itwill be further appreciated that the provision of the roller RO performs the important job of orientating correctly the leading border of the paper, so as to orientate the latter according to the required inlet or feed direction, without sensing the initial pre-bending that the paper may present in the opposite direction.
The arrangement of two folding sets as shown in Figure 1 permits a pyramid effect to be eliminated, this effect being present in the known roller type folding machine. This effect is usually present when relatively long sheets have to be folded since, if the number of folded portions is increased, the latter results always in that each succeeding sheet folded is a little shorter than the preceding folded layers, so that the paper concertina folded packet so produced will present a pyramid shape.