EP0130868A1 - Device for decelerating printed products in the folder of a rotary printing machine - Google Patents

Abstract

The invention relates to a device for slowing down copies in a folding angle of a known type. According to the invention, vacuum generating means (21-22) each have at least one series of holes (23) arranged in the direction of advance of the copy to be closed by it one after the other until '' the closing of all the holes in the series of holes, which corresponds to a maximum depression and therefore to a maximum deceleration of the specimen. The invention applies to the last stage of the bending machines used in connection with the rotary presses.

Description

knife square folds which are used as the final stage of the folding machines used in connection with rotary presses.

• - Pli triangle ou, parfois, coupe longitudinale en deux rubans ou plus, avec utilisation de barres de retournement en vue de superposer ces rubans ;
• - Perforation longitudinale et/ou transversale ou marquage à la molette pour préparer les plis suivants ;
• - Coupe entre deux cylindres dont l'un est équipé d'une scie suivant l'une au moins de ses génératrices ;
• - Réalisation du premier pli, qui est perpendiculaire au sens de déplacement de la bande à l'aide d'une lame engageante, montée sur l'un des cylindres et introduisant les exemplaires dans une mâchoire portée par le cylindre voisin ;
• - Prendre les exemplaires dans des cordons entraînés, à la périphérie du cylindre plieur (à l'aide de 4 ou plus de 4 cordons entraînés parallèles entre eux) de façon à les amener au pli d'équerre ;
• - Réalisation du pli d'équerre (parallèle au pli triangle et à la direction de déplacement du papier). C'est en cet endroit que se situe l'invention ;
• - Ralentissement de l'exemplaire dans des raquettes ou araignées qui le déposent sur le tapis de réception.

Specialists in this technique know that these folders perform a variety of folds and operations listed below:

• - Triangle fold or, sometimes, longitudinal cut into two or more ribbons, with the use of turning bars in order to superimpose these ribbons;
• - Longitudinal and / or transverse perforation or marking with a hand wheel to prepare the following folds;
• - Cut between two cylinders, one of which is equipped with a saw along at least one of its generators;
• - Realization of the first fold, which is perpendicular to the direction of movement of the strip using an engaging blade, mounted on one of the cylinders and introducing the specimens in a jaw carried by the neighboring cylinder;
• - Take the specimens in entrained cords, at the periphery of the folding cylinder (using 4 or more of 4 entrained cords parallel to each other) so as to bring them to the square fold;
• - Realization of the square fold (parallel to the triangle fold and to the direction of movement of the paper). This is where the invention is located;
• - Slowdown of the item in rackets or spiders which deposit it on the receiving mat.

In a conventional square fold (see Figures 1 to 3 of the accompanying drawings) whose invention constitutes an improvement, the specimens 1 are taken from the folding cylinder 2 by a plurality of cords 3 and 4, to be led to the square bend itself 30.

On the folding cylinder, which rotates, for example anticlockwise, there are a certain number of folding couples made up of fixed jaws 5 or "beak bars", machined in the cylinder proper (c 'is a notch parallel to a generator of the cylinder) and a movable blade or "gripping blade 6, which cooperates with 5. While the cylinder 2 rotates, in the direction of the arrow, a cam opens the blade 6, while a set of fixed strippers 7, mounted in a plurality of circular grooves machined in the cylinder 2, takes off the specimen from the jaw.

A loop of cords 3, supported above the copy by a deflection pulley 8 and driven at the speed of the press by a drive roller 9, keeps the copies in a straight line.

Another loop of driven cords 4, installed under example 1, drives the latter towards the square bend. This loop is installed between a mad return pulley 10, mounted near the strippers and is driven by a controlled roller 11.

In fact, the specimen 1, detached from the jaw 5 and 6, is pinched between the cords 3 and 4, to be drawn towards the square fold.

Generally, there are four upper cords 3 and four lower cords 4 arranged side by side on each side. Over a certain length greater than that of the example, a square fold table 12 extends under the lower cords. This table is open, in its center by a slot 13, parallel to the direction of movement of the copies.

It is important to note, that in most folding machines of this type, the copies move at machine speed (if no slowdown of the copy has been achieved before this stage) and that the copies have been folded in two (first fold) and therefore are twice as short as the machine cut.

Consequently, in this case, two backs of notebooks are separated by one section, while the length of these notebooks is only half a section.

This means that there is a paperless space equal to the length of a folded copy, between two copies.

The proportions described above of the paperless space in relation to the length of the copy can be variable (in particular if there is a slowdown in the folder, or if the fold made upstream of the square fold is different from a simple fold in 2, or "1st fold") without thereby departing from the scope of the invention.

The copies 1, pinched between the cords 3 and 4 then arrive at a stop 14, which is perpendicular to the direction of movement of the paper (see FIG. 3).

This stop, pressed against the table of the square fold 12 is machined and carries notches 15 to allow passage to the upper and lower cords 3 and 4. The purpose of this head stop is to temporarily maintain the item when the he succeeded, pushed by cords 3 and 4.

Under the slot 13, two fold rollers 16 and 17, rotating in opposite directions are driven at the desired speed. The roller 16 rotates clockwise, shown in Figure 2, while the roller 17 rotates counterclockwise. A blade 30. or knife, suitably articulated to the frame by the axis 18 and moved from top to bottom by the crank pin 19 and the connecting rod 20 introduces the copy 1 between the folding rollers 16 and 17 to fold it (see FIG. 2 ). The crankpin 19 is linked to the machine drive to perform a revolution each time a copy is sent to the square fold. The folding rollers 16, 17 are also linked to the driving of the machine so that the folding speed is sufficient to fold one copy completely before the next arrives.

The phase of the blade of the square fold knife, with respect to the introduction of the copies by the cylinder 2, is such that the blade 30 touches the copy approximately when the latter reaches the head stop.

In high-speed bending machines, the copy driven by the two sets of cords reaches the head stop 14 very quickly and tears or twists permanently.

The sudden stop on the back of the copy book, from full machine speed, to complete stop gives rise to problems such as: torn pieces of paper or folds at random or deflected randomly, rebounds on the stopper at the time of contact and before the blade has touched the paper.

All this leads to the imprecision of the fold.

Several systems are used to slow down the paper before it comes into contact with the stop and absorb part of its kinetic energy, such as fixed brushes pressed against the table 12 so as to increase the frictional forces in the last part of the race.

Systems slowing down the copy by its rear edge are better because they tend to straighten the sheet, but they have the disadvantage of being more complex.

It is one of the objects of the invention to slow down the copy when it is heading towards the stop; and one of the advantages of the invention, which will be better understood later on, is that it slows down the copy not only by its back, forwards but also by a large part of its surface.

Another object of the invention is to avoid unwanted folds and the horns at the last moment of folding, as will be explained below and also the rebound on head stop.

According to the invention, a device for slowing down the copies in a knife angle fold of a known type comprises means for producing vacuum. or depression acting on each copy to slow it down gradually, as it approaches the stop placed perpendicular to the direction of movement of the copies, and to avoid the rebound of the copy on this stop and to avoid the production of false folds and horns by aerodynamic effect in the last time of folding by producing a tension of the paper at the tail of the copies being folded then by placing in the sudden atmosphere of the means of producing vacuum.

The vacuum generating means each have at least one series of holes arranged in the direction of advancement of the copy to be closed by it one after the other until all the holes in the series are closed. of holes, which corresponds to a maximum depression and therefore to a maximum deceleration of the specimen.

• - la figure 1 est une vue de face et partiellement en coupe d'un pli d'équerre à couteau conventionnel ;
• - la figure 2 est une vue en coupe suivant la ligne II-II de la figure 1 ;
• - la figure 3 est une vue en coupe suivant la ligne III-III de la figure 1 ;
• - la figure 4 est une vue en coupe d'un pli d'équerre à couteau muni de boîtes à dépression suivant l'invention ;
• - la figure 5 est une vue en coupe de l'une de ces boîtes selon un plan perpendiculaire au plan de lecture de la figure 4 ;
• - la figure 6 est un diagramme de la dépression, en fonction du temps ; et
• - la figure 7 est une vue en coupe montrant des boîtes à air surpressé au lieu de boîtes à dépression.

Other characteristics and advantages of the present invention will emerge from the description which follows, given with reference to the appended drawings in which:

• - Figure 1 is a front view and partially in section of a conventional knife square fold;
• - Figure 2 is a sectional view along line II-II of Figure 1;
• - Figure 3 is a sectional view along line III-III of Figure 1;
• - Figure 4 is a sectional view of a knife edge fold provided with vacuum boxes according to the invention;
• - Figure 5 is a sectional view of one of these boxes along a plane perpendicular to the reading plane of Figure 4;
• - Figure 6 is a diagram of the depression, as a function of time; and
• - Figure 7 is a sectional view showing compressed air boxes instead of vacuum boxes.

The present invention essentially consists in adding to a conventional square knife fold, as described above, two vacuum boxes 21 and 22 extending longitudinally and parallel to the fold rollers 16 and 17 and placed outside the passage of the cords 3 and 4. The vacuum boxes are preferably located between two sets of cords, on each side of the slot 13 and symmetrically by compared to it.

The vacuum boxes consist of a U-shaped iron, plugged at both ends by a welded sheet and fixed under the square fold table 12 in an airtight manner.

Above these boxes, the table 12 is pierced by a plurality of holes 23 extending over the length of the box and placed so that the hole closest to the stop is drilled at a distance between 50 and 75 mm from the stop, while the hole furthest from it is. at a distance less than the length of the copy arriving at the right angle.

Four holes have been shown in Figure 5 but it is obvious that any number of holes can be drilled without departing from the scope of the invention.

The holes can have a diameter between 10 and 20 mm, or any other suitable diameter.

A tube 24, welded to the box 21 allows a partial vacuum to be produced in this box. Similarly, a tube 25 fixed to the box 22 is also used for this purpose. The pipes 24 and 25 are connected by a flexible hose to a T-junction, 26, so that the two sides of the flexible hose 27 have the same shape and the same length.

From the T-connector, 26, the air is evacuated to a blower 28 by a hose 27. This blower is driven by an electric motor in a manner known per se.

A typical diameter of pipes and hoses is

The blower can be provided to give a vacuum of 2 meters of water, when the flow is ² 00 m ³ / h.

A butterfly valve 29 is arranged in by-pass on the hose 27, to allow air to enter the blower 28 directly instead of coming from boxes 21 and 22. This valve is actuated in a known manner by a telemotor depending on the speed of the press. The throttle valve is open at low speeds and closed at high speeds.

• Quand un exemplaire, sur son chemin sur la butée de tête, entraîné par les courroies, passe au-dessus des trous 23a, 23b, 23c et 23d, il obture successivement ces trous.

The operating principle is as follows:

• When a specimen, on its way on the head stop, driven by the belts, passes over the holes 23a, 23b, 23c and 23d, it successively closes these holes.

When all the holes are closed, the depression in the boxes 21 and 22 reaches a higher value and the copy is then pressed against the table 12 by the pressure difference between the pressure prevailing in the boxes 21 and 22 and the atmospheric pressure . There is friction between the item and the table, which causes the item to slow down.

In slowing down, the back or fold of the item is not the only one to receive efforts, but friction is exerted on a large part of the item.

While the copy is stopped on the stop, it is folded by the blade 30 which introduces it between the two rollers 16 and 17 which cooperate in the folding.

Meanwhile, the next item 1 continues on its way to the head stop.

The blade 30 and the fold rollers pull the copy towards the center of the table where the slot 13 is located, in which it disappears under the table 12.

On its way to the center, the copy clears the row of holes 23, suddenly which lowers the depression in the two boxes.

Figure 6 is a diagram of the law of depression in boxes, as a function of time. The depression increases progressively, as new holes are closed by the advance of the specimen, then suddenly drops to atmospheric pressure, as soon as the specimen being folded clears all the holes simultaneously.

The advantage of these vacuum boxes is to slow the copy, on its way to the stop and also to keep the paper taut during the folding of the copy, thus reducing the problems of tearing and wrinkling of the paper on the knife of the square fold.

Another interesting means of carrying out the invention is to drive the blower at the speed of the press, instead of driving it at constant speed by an electric motor.

The purpose of the butterfly valve 29 in the description above is to reduce the vacuum at low press speeds.

The reason for this is that the kinetic energy contained in a copy is proportional to the square of the speed of this copy, therefore to the square of the speed of the press.

At low speeds, this kinetic energy is very low and the depression stops the specimen too early, in its path towards the stop; the fold is made before the stop and bending jams result.

The vacuum of a conventional blower is roughly proportional to the square of its drive speed, which means that by driving the blower at machine speed, the vacuum is always appropriate and proportional to the kinetic energy contained in the copy . In this case, the butterfly 29 would only be used to take into account the quality of the folded paper, its grammage and its coefficient of friction on the table, but more than the speed of the press.

The angle fold described in the present application is only one possibility. People who know the printing press know of other ways of introducing paper between the two fold rolls such as the well-known "Rotary" or "hypocycloidal" model, in which the tip of the blade describes a straight line instead of of an arc.

It is obvious that this type of square fold or other similar models can be used without going out within the scope of the invention, the type of movement of the blade having only been described for information.

Other variations may also include larger vacuum boxes extending more widely under the table, from the side to the center of the table.

A blowing of compressed air above the table, produced by overpressure boxes (31) located above the copy and provided with holes (32), opposite corresponding holes (33) drilled in the table (see Figure 7) also constitutes an application of the invention, each copy being able to slide in a passage (34) formed between these overpressure boxes and the table.

It is understood that the present invention has only been described and shown as a preferred example and that it is possible to provide equivalences in its constituent elements without, however, departing from the scope of the invention.

Claims (7)

1. Device for slowing down the copies to be folded in a square fold of known type, comprising a table (12) having a slot (13) parallel to the direction of movement of the copies, a stop (14) perpendicular to this direction, two fold rollers (16 and 17) arranged under the slot (13) and a blade (30) pulling with said fold rolls each copy considered towards the center of the table where said slot is located and in which it disappears, characterized in it further comprises, vacuum generating means or depression (21, 22) acting on each copy to be folded for the slow pro ^g res- sively, gradually as it approaches said abutment (14) the braking force being applied in a way, on the one hand, to avoid the rebound of the copy on this stop (14) and, on the other hand, to produce a tension of the copy until a sudden release of vacuum means. 2. Device according to claim 1 characterized in that the vacuum generating means (21-22) each have at least one series of holes (23) arranged in the direction of advance of the item to be folded to be closed by him one after the other until all the holes in the series of holes are closed, which corresponds to a maximum depression and therefore to a maximum deceleration of the specimen. 3. Device according to any one of claims 1 and 2 characterized in that each means of producing vacuum is constituted by a box fixed under said table and whose series of holes (23) is drilled in the table. 4. Device according to claim 3 characterized in that it comprises two vacuum boxes arranged under the table (12) on either side of the slot (13) and therefore rolls of folds (16-17). 5. Device according to any one of claims 1 and 2 characterized in that the means of progressive slowdown of the copy on the table are constituted by pressure relief boxes arranged above the table, the pressure varying by successive obturations by the copy passing between the boxes and the table of cooperating holes (32-33) in the boxes and in the table. 6. Device according to any one of claims 1 to 5 characterized in that it comprises a fan driven at constant speed (28) to obtain the vacuum, a throttling means (29) allowing the pressure to be adjusted as a function various parameters, machine speed, paper weight and friction coefficient. 7. Device according to any one of claims 1 to 5 characterized in that it comprises a blower (28) driven by the press to obtain a depression roughly proportional to the kinetic energy contained in the copy, a means of throttle (29) mounted as a "by-pass" used to compensate for the grammage and the coefficient of friction.

Images