DE2528008A1 - ROTARY PRINTING MACHINE - Google Patents

Description

ROCKWELL INTERNATIONAL CORPORATION, Pittsburgh, Pennsylvania 15219, V.St.A.

Rotary printing press

The invention relates to a rotary printing press with a plate cylinder and a cooperating therewith Cylinder, a printing gap formed between the cylinders, a number of fastened on the printing cylinder Sets of printing plates, between those at regular intervals around the circumference of the plate cylinder Longitudinal slots run, and a number of the individual plate sets attaching to the plate cylinder Panel mounting assembly, wherein the panel mounting assembly for one of the plate sets in the circumferential direction of the plate cylinder relative to the plate fastening

509883/0731

Bremen office: Bremen accounts: Munich office:

D-2800 Bremen 1 Bremer Bank, Bremen D-8000 Munich 90

P.O. Box 786, Feldstrasse 24 (BLZ 29080010) 1001449 Schlotthauer Strasse 3

Tel-jf.in: (0421) * 74044 Telephone: (089) 652321

Telex: 244958 bopatd PSchA Hamburg

BOEHMERT & BOEHMERT

supply arrangement for another of the plate sets such is offset that the longitudinal gaps in the plate sets are offset from one another in the circumferential direction by a staggering angle.

In conventional rotary printing machines, such as those used in newspaper printing for printing paper webs is a number of semi-cylindrical clichés or printing plates around the circumference of the respective plate cylinder so arranged that there are longitudinal gaps or longitudinal gaps between the front and rear edges of the panels develop. In a press for double-format printing, for example, the plate cylinders carry four Plates in the transverse direction and two plates in the circumferential direction, so that at least two such gaps, with a spacing of 180 °, can be formed in each set of four plates. If this column is like that are aligned with one another so that there are continuous gaps along the entire length of the plate cylinder, heavy impacts are exerted on the plate cylinder and the printing cylinder that interacts with it, which occur every time a gap passes through the pressure gap between the cylinders. the The resulting oscillations or vibrations have a disadvantageous effect on the print quality. When producing half-size pages or tabloid formats there are two additional gaps in each set of plates, eliminating the vibration problems to be further strengthened.

To the size of the push & and thus also the resulting It takes a long time to reduce vibrations

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At that time it was customary to stagger the plates around the circumference of the plate cylinder. With other words that Plates are arranged so that the gaps that swipe the four-plate set at one end of the plate cylinder, angularly relative to the gaps formed by the set of four plates at the other end of the plate cylinder be angularly offset. As a result, each gap extends only half the length of the plate cylinder. So the gaps pass through the printing gap with staggered intervals in each printing cycle, so that the abrupt pressure changes between the plate cylinder and the impression cylinder are substantial be reduced.

Although this staggering of the plates has resulted in the severity of the impacts exerted on the cylinders could be reduced, this does not solve the streak problems caused by the gap-induced vibrations are caused and especially at normal operating speeds prevalence. It has been found that this is due to the fact that the previously used Stagger angles necessarily produce pulses at normal operating speeds, which occur at intervals that are equal to or equal to the natural or natural period of the cylinders are an integral multiple of this eigenperiod. Accordingly, the cylinders vibrate with amplitudes which are considerably larger than they would be if the pulses occurred at different intervals.

509883/0731

BOEHMERT & BOEHMERT

The invention is based on the object of a rotary printing press of the type mentioned to create with a plate cylinder, in which the pulses or Disturbances caused by the longitudinal gaps between the printing plates, not with the natural period of the cylinder or a fraction of this period are synchronous, thereby eliminating the Schlieren problem to fix.

According to the invention this object is achieved in that the graduation angle is 4-8 to 57 °.

Thus, according to the invention, the panel mounting assemblies arranged at irregular intervals around the circumference of the plate cylinder, so that then, if a full plate assembly is provided on the plate cylinder, which is provided by a plate set gaps formed angularly relative to the gaps formed by an adjacent set of plates are offset or staggered by an angle that is not a straight divider of 560. As a result, they are Fissure periods are unequal and can never combine in such a way that disturbances are repeated in phase occur with the natural period of the system.

Further features and advantages of the invention emerge from the claims and from the following description, in which an exemplary embodiment is explained in detail with reference to the drawing. It shows

Fig. 1 in a schematic side view a

conventional newspaper rotary press;

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FIG. 2 shows a pair of printing cylinders in FIG. 1

machine shown in perspective view;

Figure 3 is a section taken substantially along line 3-3 of Figure 2;

Fig. 4-7 graphical representations of the relationship between the gap-induced vibrations and the natural frequencies of the printing cylinders at different angles;

Fig. 8

and Fig. 9 graphs the differences in deflection amplitudes in staggered wraps between 30 and 60 and a staggering angle of 51 speeds over the normal range of Druckpressenge; and

10 shows a graph of the vibration properties versus those used in practice Range of graduation angles.

The following is an embodiment of the invention described with reference to the drawing, which, as carried out, the invention in newspaper eotation printing machines (printing press type) shows. Such Eotatxonsdruckmaschinen have printing cylinders, which six in the transverse direction Can accommodate printing plates (halftone clichés) and two printing plates in the circumferential direction. Such printing machines or presses are commonly called 6x2 presses in contrast to the more common 4 x 2 presses. The invention is particularly useful with presses This size is advantageous because longer cylinders naturally involve greater oscillations or vibrations can.

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The invention can, but also advantageously Use smaller 4 χ 2 presses, also with lithographic presses Offset newspaper rotation printing machines comparable size. Also the use in such modified, modified embodiments of Printing machines or presses is within the scope of the invention, as expressed in the description and in the claims.

For example, it is clear to anyone skilled in the art that in the relief printing process the paper web passes through a gap which is formed between the plate and the printing cylinders. In the lithographic offset printing process the paper web runs through the gap between the printing felt cylinder and the Printing cylinder or between two printing felt or dampening cylinders. Nevertheless, they form Plate> and the printing felt cylinder one under considerable Pressure force standing gap, so that the grooves or gaps that are provided in these cylinders, around the fastening devices for the printing plate record, cause vibrations in all printing cylinders. The angular arrangement of these gaps is therefore just as important as the arrangement of the gaps between There are printing plates in relief printing machines.

In Fig. 1 of the drawing, the invention is shown in a typical newspaper rotary printing press, which having mutually spaced side frame parts 10. The plate cylinder 11 and the cooperating therewith Printing cylinder 12 of a first pair of printing cylinders are rotatably mounted in the side parts 10.

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These cylinders form a first pressure gap at I3 for printing one side of a paper web 14. A second pair of impression cylinders is through a plate cylinder 16 and a pressure cylinder 17 cooperating therewith is formed. These cylinders are also in the Side frame parts rotatably mounted and form a second pressure gap 18 through which the other side of the Paper web 14 is printed.

From a reservoir, not shown, the printing plates printing ink or ink are supplied to the printing cylinder 11 by means of a dampening unit. The dampening system 21 consists of a number of distributor rollers 22, ink rollers 23 and two or more form ink rollers 24, which come into contact with the plates on the cylinder 11. Similarly, the panels get on the Plate cylinder 16 color from a zx ^ eiten, not shown Reservoir, via a dampening system, generally designated 26, which also has ink distribution rollers 27, ink rollers 28 and form ink rollers 29.

The plate cylinder 11, 16 and the co-operating pressure cylinder 12, I7 are adjusted so that maintain considerable pressure between the cooperating surfaces in the pressure nips 13,18 will. Typically a compression of about 0.2 mm (0.008 ") is used for adequate transfer of ink or printing ink from the plates onto the paper web. While the paper web 14 therefore runs forward in the direction indicated in FIG. 1, a plurality of color imprints is made on this from the plate cylinder 11 when passing through

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applied through the pressure gap I3. After that, the Paper web passed through the nip 18, where a corresponding number of imprints on the opposite Page is applied by means of the plate cylinder 16. When leaving the press, the The printed paper web is then cut, folded, merged with other paper webs and finally shipped as a finished newspaper, with all of these operations run at high speed.

The number of pages printed by each plate cylinder appears to depend on the size of the cylinder and the number of plates placed on it. In the present example, each plate cylinder can print 12 full-size double pages per revolution. As can be seen in Fig. 2, namely twelve cliché or printing plates 3I are arranged on its peripheral surface. The printing plates are preferably arranged in sets of four printing plates each, the printing plates 3I at the left end of the cylinder 11, seen in FIG , are in fact called 3I ^'a ls "medium" set the middle.

The printing plates are known to have semi-cylindrical ones Shape so that they can be quickly removed and replaced if necessary. When the printing plates so be mounted on the plate cylinder between the - in the circumferential direction - front and rear end of each plate pair column 32 formed. These gaps are 180 ° apart and fall

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with the upper or lower edge of the double sheet together. If pages are to be printed in fabloid format, so each printing plate naturally has an artificial printing gap, as denoted by 32a in FIG. 2 is. This artificial pressure gap 32a is opposite the natural pressure gaps 32 offset by 90 °, so it is located in the middle between them. In in such a case, each plate set has 4 x longitudinal gaps in total. Every plate cylinder creates then 24 tabloid pages per revolution.

In order to support the paper web 14 in a suitable manner as it passes through the printing nip 13, it is customary to provide the printing cylinder 12 with a resilient printing felt 33. Preferably, the pressure felt consists of three sections 33, 33 'and 33' ¹ ·> of which each section one two. Plates covered a wide area of the printing cylinder. The printing felts are completely wrapped around the circumference of the cylinder. The respective ends of the printing cylinders are held in their position by clamping devices not shown. The clamping devices or fastening means are located within grooves or slots 34-> 3 ^ ^f , 34- "which are provided for this purpose in the circumferential surface of the printing cylinder. Only one such groove is required for each printing felt section.
The rods are angularly arranged on the printing cylinder so that they coincide with a gap 32 in the associated printing plate set.

The printing plates are in their position on the
Plate cylinder by means of resilient locking

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directions held as shown in FIG. This is done in such a way that the leading edge of a printing plate is adjacent to the rear edge of the other panel, whereby the gaps 32 are formed. As can be seen from Fig. 3, the front edges of two panels of the "front" Plate set in place by a plurality of aligned, relatively fixed fingers 36 held by the peripheral surface of the cylinder protrude from and engage slots 37 milled into the inner surface of the panels. The rear The ends of each plate of the "front" plate set are in turn maintained by a constant tension Means held in position in the form of a number of fingers 38 which are pivotable in blocks 39 which are formed on an operating parts 41 are attached. When the operating shaft 41 clockwise is rotated, the fingers 38 are withdrawn under the cylinder surface, whereby the Attaching and removing the pressure plates is made possible or facilitated. If the shaft 41 against the Is rotated clockwise, the fingers 38 engage in the milled slots 42 in the plate and lock them in their position. During the final movement of the operating shaft 41 in In a clockwise direction, keys 43 provided on each of the fingers 38 press on compression springs 44 which are located in recesses 46 are arranged, which are formed in the shaft 41, whereby locked onto the plate in the Constant tension is exerted. The "middle" plate set is secured by a separate plate clamp assembly ^ which are designated as a whole with 5I

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is locked and held in position. The elements are identical to those of the clamping or fastening means for the "front" Ρ, -attsatz identical and have similar reference numerals, but in each case the letter "a" is added. The only difference is that the actuating shaft 4-1 a is an extension has in such a way that it is manually between the locking and the release division of the "front" End of the cylinder can be moved out.

The respective actuating shaft can be actuated by collar and knee linkage, as shown schematically are shown below in Fig. 3. Since these components are not essential to the invention, however they are not described in detail. Rather, it is used for a complete description of the entire locking assembly Reference is made to U.S. Patent 2,900,903.

It should also be noted that the plates of the "rear" pressure plate set are arranged so that they can be secured in position by identical clamping arrangements. The locking finger and the operating shafts of the "rear" set of plates are connected to the corresponding elements of the Klemmanordjiung the "front" set a / usge ^ ieSifcetSund may be by linkages are .vegt ^i, the "rear" end of the plate cylinder are arranged.

From the above description it is clear that in a press of the type described in FIG. 1 at paper web speeds of approximately 610 mpm (200Q fpm)

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the plate and impression cylinders were subjected to severe impacts when the gaps 32 pass through the printing gap, especially if the column 32 runs along the entire length Width of the cylinders are aligned with each other. This would be confessed because of the proportion high pressure between the cylinders would be abruptly interrupted. The effect would be made worse that the printing felts on the printing cylinder are resilient and elastic are trained. To reduce the size of the bumps, it has long been the practice to stagger the plate clamping assemblies by an angle X as shown in FIG. 3 so that the Columns of a plate set angularly relative to the columns in an adjacent set or in adjacent ones Sets of printing plates are staggered. This reduces the pressure between the interacting Cylinders are not completely eliminated at any point in the circle, resulting in improved results can be achieved. But shocks or pressure pulses are still on the printing cylinder in such a way Measure applied that arise in these vibrations or oscillations, which are easily called so-called "Schlieren" appear in the printed matter.

It has now been found that the streak problem is mainly due to those previously used Stagger angle is due and that the operating condition can be drastically improved by the appropriate angle is chosen.

So far it has been customary to provide cylinders with stagger angles of either 4-5 °, 60 ° or 90 °. Of the

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An angle of 90 ° is used when printing double-page certificates widely used, but it is impractical for large tabloid products. If tabloid size products, half-format products would have to be printed, so would the artificial gaps in one set of plates obviously aligned with the natural crevices of an adjacent set of plates, thereby preventing the purpose of staggering by 90 °.

Stagger angles of 4-5 ° and 60 ° have so far been the most common. Since the gap joints or gap impulses, which are generated by these angles, but integral multiples of the natural or natural period the cylinder at normal operating speeds, as has been shown, remained the Streaking continues to be a serious problem.

The effects produced by conventional stagger angles can be better understood by reference to understand Figs. 4-7. Referring to Fig. 4-, there is shown the condition which occurs when each of the three Plate sets is staggered at an angle of 30 ° relative to the adjacent set. This arrangement will not actually used, but it is used to show an extreme operating condition.

As shown, the natural or eigen period is of the system 0.0093 see. For this reason, a press speed causes the a rotation of 30 ° in 0.003 seconds. results, gap-induced pulses with exactly the same period. To the-

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According to this, the magnitude of the vibrations is kept at a maximum value, creating serious streak problems would occur.

One could now think of the fact that by such an arrangement of the staggering angle that the column on the Ends of the cylinders aligned and 30 with respect to the central gap are staggered, the resonance condition could be alleviated, because every third Shock would be missing. However, because of the impulsive nature of the disturbance, this is not the case. Fig. 5 shows an example this operating condition, from which it follows that only a very slight reduction in amplitude can be achieved in the oscillation cycle.

It could also be thought that a sufficiently large distance between the columns, in namely, that the nip period equals the natural period of the system only at one press speed above the operating speed range would avoid the resonance-like condition could lead. Because of the impulsive nature of the disturbance, however, the resonance-like condition becomes always reached if the split period is any integer multiple of the natural period of the system amounts to. So if the self-period condition is moved out of the normal speed range a partial period condition is introduced.

This can be seen from the illustration in FIG. 6, where the gaps are staggered by 4-5 °. In this case the period between disturbances is equal to that

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Double the natural period, reducing the movement of the Cylinder is amplified every other cycle and still large cylinder movements occur. From this It can be seen clearly that there is no uniform spacing between the columns at a useful rate s area leads in which the gap impulses and the natural period or multiples thereof are not coincide.

It has now been found, through very thorough and careful study, that by arranging the gaps of one set of plates so that they are spaced from the gaps of an adjacent set by an angle which is not an even divisor of J60 ^o , a considerable reduction is achieved the amplitude of the vibrations can be achieved. In this case, there is no possibility that resonance-like pulses from one gap will be exactly in phase with the pulses caused by the other gap, as was the case with the examples discussed above. Rather, the vibrations caused by one gap will tend towards that of others. Counteract generated oscillations or vibrations.

In Fig. 7 the movements are shown, which are exactly the same with a gap distance of 5I Press speed as in Fig. 5 occur. From this it follows that instead of mutual reinforcement, which was achieved in the previous example, the disturbance of one gap tends to be has · caused by the previous gap

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To dampen movements. Accordingly, the vibrating The cylinder amplitudes are reduced.

The entire effect over the operating speed range of the rotary printing press can be seen from FIGS. 8 and 9, in which the maximum peak-to-peak deflections of the plate and impression cylinders as a function of the press speed for the in connection with Fig. 5 and 7 discussed gap angle plotted are. From these graphs it can be seen that over most of the operating speed range there are only minor differences between the two arrangements. At the speed at which the resonance-like condition would have to occur, however, provides the staggering angle from 5> 1 much smaller distractions. To the combined To determine the effect of maximum deflection and press speed, a "uniformity index" use the following form:

η X ₁ + In j η 2 1 ^e m i - 1 ^e η. η

PI =

2 "

Here, x ^ means the maximum peak-to-peak deflection of cylinder 1 at speed i and x _? the maximum peak- _to- peak deflection of the cylinder 2 at the speed i, the summation being carried out over η speeds in the operating speed range.

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If this "uniformity index" is applied to gap distances of 30 to 60 °, the representation shown in FIG. 10 results. These data clearly show that a kinimum of the deflection amplitude is reached at gap angles between 30 and 45 ° and between 45 and 60, the optimal spacing for the natural gap being 51 °. The optimal gap distance between the natural gap and the next artificial gap when printing tabloid formats is 39 ° · Since the direction in which the
Angle is measured is arbitrary and the total angle of interest is 90 °, these two minima are effectively equivalent. That is, the larger angle is equal to 90 minus the smaller angle.

From this it follows that by a distance of the natural gaps of a set of plates of 43 to 57 °, preferably 5 ^ »from the natural gaps of the
adjacent set or sets of plates
significantly improved results compared to the previous ones
used gap stagger angle can be achieved
can.

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Claims (3)

BOEHMERT & BOEHMERT 252S008 R 846 CLAIMS 1.! Rotary printing press with a plate cylinder and m cooperating cylinder, a pressure gap formed between the cylinders, a number of sets of printing plates mounted on the printing cylinder, between them at regular intervals around the circumference The plate cylinder has longitudinal slots, and a number of the individual plate sets on the plate cylinder mounting plate mounting assemblies, the plate mounting assembly for one of the Plate sets in the circumferential direction of the plate cylinder is offset relative to the plate mounting arrangement for another of the plate sets such that the Longitudinal gaps in the plate sets are offset from one another in the circumferential direction by a staggering angle, 509883/0731 BOEHMLRT & BCEtIiMERT 252 * 008 characterized in that the stagger angle 48 to 57 °. 2. Rotary printing machine according to claim 1, characterized in that o indicates that the staggering angle is 5 ^ ". 3. Rotary printing machine according to claim 1 or 2, characterized in that the with the plate cylinder (11, 16) interacting pressure cylinders (12, 17) its circumference a number of printing felts (33, 33% 33 ") having; in that the printing felts are secured on the cylinder by a plurality of clamping devices; that in the circumferential surface of the cylinder a number of longitudinal grooves (34, 3 ^ ', 34 ") to accommodate the clamping devices is provided; and that the groove for one of the gill devices in the circumferential direction relative to the Groove for another of the clamping devices is offset by an angle equal to the stagger angle between the gaps (32) on the plate cylinder (11, 16) is.