EP0306987A2 - Forme cylinder for a rotary printing machine - Google Patents

Abstract

The printing cylinder has a thin outer shell (12), to which the printing plate is attached. The printing plate is claimed to the cylinder ends and contains peripheral chambers with a non-compressible liq. as well as a liq. displacement system. The displacement is carried out by a threaded fin (21) screwed in a line (23) coupled to the liq. chambers. At one fin end is a retainer (26), coupled to a head-shaped part (25) of a piston (20). The piston at the end has annular grooves for sealing rings.

Description

The above invention relates to a printing cylinder for a rotary printing machine, in which the printing plate is clamped in the form of a cylindrical winding plate on the outer surface of the printing cylinder by expanding a tubular, elastic, thin jacket. The cylinder diameter is increased by acting on the jacket from the inside of a non-compressible liquid which can be controlled by means of displacement devices of the liquid.

Cylinders for clamping tubular printing plates rotary printing machines have already become known, e.g. Gravure printing plates, matrices for flexographic printing or for other bodies of a rotary printing machine, such as rubber-like sleeves for pressure cylinders, cylinder-shaped pressure plates for anilox cylinders, coverings for drive cylinders and similar devices.

The known displacement device, which leads to an increase in the pressure in the liquid and to the expansion of the outer jacket of the cylinder are used, have an actuating screw to generate a compressive force which acts directly on the fluid, in the manner of a piston, often through the intermediate storage of a spring. Due to the machining tolerances of the screw or the threaded pin, as well as the threaded hole in the pressure line, pressure loss can occur, which lead to a change in the fluid pressure and thus cause a change in the outer circumference of the jacket. Furthermore, the disadvantage can arise that the compression is not carried out directly in the axial direction, which leads to further sealing losses and / or greater wear of the components. The use of a spring, together with a separately provided piston, requires the installation of three components, the above-mentioned disadvantages not being eliminated.

It is also necessary that the pressure plate or possibly the sleeve-like, tubular casing on the pressure cylinder must be arranged with high accuracy in the axial direction of the cylinder before the cylinder is expanded, in order to avoid undesired displacements in the transverse direction. Furthermore, it must be taken into account that the edge areas of the known printing plate have sharp edges or edges angled by 90 °, which would adversely affect the operation of a doctor blade, i.e. that component which is provided in order to remove the excess ink and which moves with a reciprocating movement in the longitudinal direction of the printing cylinder.

Especially when the printing plate is made from a flat plate it is always difficult to avoid sharp edges on the plate edges. As a result, the doctor blade is not only impaired in its oscillating movement and in its mode of operation, but it is also subject to greater wear.

When a known printing cylinder is used in combination with a printing plate which consists of a flat metal plate coated with photosensitive material and is wound in such a way that the printing plate takes on a cylindrical shape, a further disadvantage occurs. Since the joint between the ends of the pressure plate has a certain thickness, even if this thickening can be partially weakened, it is not possible to remove it completely.

If a cylinder was used which had an enlarged diameter, which was done in a conventional manner, a bead or a longitudinally extending elevation would result at the abutment point of the pressure plate, which would lead to considerable difficulties when using this type of plate.

Alternatively, in order to avoid such thickening at the abutment point of the pressure plate, it has already been proposed to propose a different type of cylinder and a pressure plate suitable therefor, the edges to be connected having a mutually complementary shape which leads to a particularly complex formation of the edges, which is not entirely without restrictions.

The use of this known type of plate is particularly advantageous in terms of the manufacturing costs of the plate, both in terms of the necessary devices as well as the time required for galvanic treatment and the etching of these plates. However, the known advantages cannot be fully used, since a thickening forms at the connection joint, on the inside of the cylindrical printing plate, due to the technical circumstances described, which occur due to the mutual connection of the plate edges of these printing plates.

The object of the above invention is to avoid the disadvantages of the prior art and the associated restrictions.

The object according to the invention is achieved in that a printing cylinder for a rotary printing press is used which has a tubular, elastic, thin jacket which is firmly and tightly connected to the ends of the cylinder body and has peripheral chambers in which a non-compressible liquid is provided and with devices for displacing the liquid, in order to bring about an enlargement of the outer circumference of the pressure cylinder and the printing cylinder is characterized in that the displacement device consists of a threaded pin which is screwed into a line which is operatively connected to the liquid chambers and which The grub screw has a receptacle at its end, which is operatively connected to a head-like thickening of a piston, and the piston has ring grooves at its other end for receiving sealing rings.

According to a further feature of the invention, the ends of the tubular jacket surface have material thickenings, in order thereby to create a seat or a recess for the arrangement of the pressure plate, the thickness of the thickening being equal to the thickness of the pressure plate, and the outer edges of the thickening are also included round off.

According to a further feature of the invention, the jacket surface of the cylinder has at least one longitudinal groove or a longitudinal seat in order to form a receptacle and holder for the connecting joint of the pressure plate, which consists of a wound plate that is joined at the end.

Further features and advantages of the invention can be found in the following description of some exemplary embodiments, which are not to be regarded as restrictive solutions, and in the accompanying drawings.

• Fig. 1 teilweise im Schnitt einen Druckzylinder gemaess der vorstehenden Erfindung;
• Fig. 2 im Schnitt ein Detail des Druckzylinders, bei dem die Verdraengungsvorrichtung sowie die Aufnahme fuer die Druckplatte gezeigt sind;
• Figur 3 und 4 im Detail den Gewindestift zur Betaetigung des Kolbens;
• Fig. 4a den Sitz fuer die Aufnahme des Kopfstueckes des Kolbens;
• Fig. 5 ein Detail einer weiteren Ausfuehrungsform des Aufnahmesitzes; und
• Fig. 6 - 10 teilweise im Schnitt verschiedene Ausfuehrungsformen des Zylindermantels mit schlitzartigen Ausnehmungen zur Aufnahme des Verbindungsstosses der Druckplatte.

The drawings show:

• Fig. 1 partially in section a pressure cylinder according to the above invention;
• 2 shows in section a detail of the printing cylinder, in which the displacement device and the receptacle for the printing plate are shown;
• Figures 3 and 4 in detail the threaded pin for actuating the piston;
• 4a the seat for receiving the head piece of the piston;
• 5 shows a detail of a further embodiment of the receiving seat; and
• Fig. 6 - 10 partly in section different embodiments of the cylinder jacket with slot-like recesses for receiving the connection joint of the pressure plate.

The printing cylinder according to the invention, which is shown in its basic features in FIG. 1 and is identified by the reference symbol 1, has two lateral bearing journals 2 and 3 for storage in the rotary printing press.

In the circumferential surface of the cylinder body 4 circumferential chambers 5 are incorporated, which are relatively flat. These chambers 5 are filled with a non-compressible liquid 11 and connected to the outside of the cylinder via a line 7. In the line 7, from the outside 8 of the cylinder, displacement devices are inserted, which are schematically identified by 9 and are described in more detail below. In the case of pressure cylinders with a short length, it may be sufficient to provide a single circumferential chamber 5.

The body 4 of the cylinder is covered by a cylindrical, tubular, thin jacket 12 which e.g. consists of spring steel or is made of plastic or other suitable materials. This elastic jacket 12 is fixed and sealed to the ends of the cylinder 1, e.g. by welding connection or other suitable connection possibilities, which are marked with 13.

The pressure plate, not shown in FIG. 1, is pushed over the mantal 12. This pressure plate can freely on the tubular jacket be moved when the liquid 11 is not under pressure. Once the tubular pressure plate is positioned on the cylinder 1, the liquid 11 is pressurized via the displacement device 9, and the outer diameter of the cylinder increases due to the elasticity of the casing 11. The pressure plate is thus uniformly distributed over the entire cylinder surface in a predetermined position curious; excited.

The construction of the printing cylinder described so far is essentially already known and is therefore no longer explained in more detail.

The displacement device 9 of the invention will now be described in more detail with reference to FIGS. 2-4a.

The displacement device 9 consists of a movable piston 20 which is displaceably mounted in the longitudinal direction in the line 7 and has a head 25 at one end and is provided at the other end with annular grooves 28 for receiving sealing rings 24. The piston 20 is operatively connected to a drive part 21, advantageously a grub screw 21, but is not rigidly connected to it. The setscrew 21 has a shape 22 for the insertion of a key. Furthermore, the pin has a thread 29 which is operatively connected to a thread 23 towards the outward exit of the line 7.

The receiving seat 26 (FIGS. 4 - 4a) of the threaded pin 20 is suitable for receiving the head 25 of the piston 20. The head is over one Taper 27 of the piston is guided in a tapered receptacle 30 of the threaded pin 21. As can be clearly seen, the head 25 of the piston is arranged in the seat 26 with a certain play. This compensates for forces that do not occur exactly in the axial direction.

Thus, by functionally separating the piston chamber from the thread chamber, the displacement device becomes particularly precise and efficient in its operation. Any tolerances that occur during the production of the threaded pin 21 or the thread in the line 7 do not influence the sealing effect of the device. Furthermore, no loads will occur due to an axial deviation of the components, since there is no rigid connection between the piston head 25 and the threaded pin 21. The proposed design is particularly simple. The parts can be easily assembled and there is the possibility of easily replacing individual components.

A further feature of the invention is always described with reference to FIG. 2.

As can be seen from this illustration, the outer surface 35 of the casing 12 has a thickening at one end or at both ends 32 (only the left end piece is shown in the figure) compared to the remaining material of the casing 12. This creates a seat or a seat for the pressure plate. The receptacle consists of the jacket 35 and stops 31, which are formed by the thickening 32.

the depth of the seat or the seat is equal to the thickness of the pressure plate to be used, which was not shown in the drawing for reasons of clarity. This ensures that when a printing plate is mounted on the cylinder 1, in accordance with the receiving seat, the outer edge zone of the printing plate comes to lie flush with the outer surface 32 of the thickening.

Furthermore, the outer edges of the thickening 32 have roundings 33. The receptacle for the printing plate, not shown in FIG. 2, was produced by mechanical processing of the casing 12 and has a circumferential groove 34, which, however, has no effect on the function of the cylinder. Alternatively, the material could also be removed chemically or electrochemically.

In this way, the squeegee for the removal of the excess printing ink, which moves back and forth and parallel to the cylinder 1, does not detect any interruption in the cylinder surface. In particular, the squeegee no longer hits an edge that is sharply deflected by 90 °, which is unavoidable with conventional winding plates.

Alternatively, as shown in Fig. 5, the seat can also be formed from two laterally arranged thickenings 40 which have covering parts 42 which rest on the cylinder end, which has a smaller diameter, in order to form a projection with respect to the surface 45 of the casing , which corresponds to the thickness of the printing plate.

The outer edge 43 is also rounded here, and the component 40 can be attached to the jacket by means of screws, adhesive connection, welding or similar connecting means.

Other alternative embodiments are also possible, e.g. the provision of the thickening on only one side of the cylinder jacket.

In a preferred manner, if the receiving seat is achieved via lateral thickenings, these thickenings are made of a material whose characteristics are similar to the characteristics of the photosensitive coating material which forms the outer surface of the printing plate. Features that should be similar relate to the coefficient of friction and hardness of the material to avoid any interruption in the continuity of the squeegee movement.

Thanks to the feature described above, to provide a circumferential recess for receiving the pressure plate, in which the entire wall thickness of the pressure plate is to be accommodated and, by providing rounded edges, an outer diameter is achieved over the entire width of the cylinder, which ensures continuity over the entire cylinder length, which is what the squeegee process significantly simplified. In an alternative solution it can be provided that only one end of the cylinder has a thickening.

In the case in which the pressure plate is designed as a closed sleeve or as an assembled sleeve with a continuous profile, both in the circumferential direction and in the radial direction, the surface (35, 45) of the jacket appears continuously.

In the case in which a pressure plate is used which is in the form of an assembled sleeve in order to achieve a continuous winding plate in which the butt joint forms an internal bend, according to the invention the jacket 12 of the cylinder has at least one recess or longitudinal groove, such as this is shown in different execution examples in FIGS. 6-10. The recess 50 shown in FIG. 6 extends in the longitudinal direction along a surface line of the surface 12 and has a depth that is greater than its width. This recess is kept somewhat wider than the width dimension of the bend, so that it is easy to insert into the recess. The groove-like recess extends in the radial direction.

Alternatively, the groove 50 could also extend inclined to the surface line of the surface 12, in the event that the butt joint of the pressure plate would be provided inclined relative to the surface, usually along a slightly inclined angle in order to reduce the usable area for the surface too much Have to put up with the printing process.

In the embodiment shown in FIG. 7, the slit-like opening 51 has a small depth, but its width is considerably larger than its depth. This type of recess is suitable for receiving and fixing a pressure plate in which the butt joint has been bent over, so as to limit the thickness of the butt joint to a minimum. With this groove, the depth is less Admission required and thus there is a very slight weakening of the jacket.

Fig. 8 shows an embodiment in which the groove-like recess 52 is angled with respect to the radial direction of the cylinder and corresponds to an abutment point in which the plate joints are not arranged at 90 ° relative to the pressure plate surface and have not been completely bent. In this way, a depth for the recess is achieved which is less than the actual height of the butt joint, without having to resort to a complete bending of the butt joints. The choice of groove type depends on various factors, including from the thickness of the cylinder jacket, thickness that can reach up to 10 mm.

FIG. 9 shows a further embodiment, in which at least one slot 53 for receiving the connection point and a further number of slots or incisions 54, which are distributed over the outer surface of the jacket 12, are provided. These latter slots have a compensating function and serve mainly to avoid the formation of an oval circumference and / or to reduce peak loads. The incisions can be covered by elastic sleeves made of steel or plastic as required. A further embodiment is shown in FIG. 10, in which the groove for receiving the connecting joint is identified by 56.

Another notch 57 is arranged in an inclined position with respect to the first groove and a third groove 58 is in the opposite one Side provided on the inside of the jacket 12. With this embodiment, a so-called clamping effect is achieved across the edges of the groove due to its expansion, expansion which the jacket experiences when the liquid in the chambers 5 is pressurized. An advantageous clamping effect for the pressure plate on the jacket 12 is obtained in this way.

As has already been described for the embodiment according to FIG. 6, a plurality of grooves can also be provided for receiving the connection joint of the pressure plate, and the groove or the grooves can be arranged inclined with respect to the surface lines of the peripheral shell if the connection point of the pressure plate is arranged inclined.

The object described is achieved with the invention. Providing a separately arranged piston, which is operatively connected to a threaded pin, essentially creates the possibility of leakage losses and pressure losses, due to machining tolerance and lack of alignment of the threaded line and the chamber receiving the piston. The provision of a recess or a seat in the circumferential direction of the printing plate makes it possible to create a smooth printing surface without interruptions, which considerably simplifies the doctoring process, also thanks to the rounding of the outer edges. Finally, the provision of one or more longitudinal grooves creates the possibility of also using pressure plates which are designed as winding plates, in which the thickness of the butt joint is not to be neglected.

Claims (16)

1. Printing cylinder for rotary printing press, consisting of a tubular, elastic, thin jacket, which is firmly and tightly connected to the ends of the pressure cylinder and has circumferential chambers that have an incompressible liquid, and with means for displacing this liquid, so that the outer To enlarge the diameter of the pressure cylinder, characterized in that the displacement devices consist of a threaded pin (21) which is screwed into a line (23) which is connected to liquid chambers (5), that the threaded pin (21) has one at its end Has receptacle (26) and is operatively connected to a head-like thickening (25) of a piston (20) and the piston (20) has ring grooves (28) at its other end for receiving sealing rings (24). 2. Printing cylinder, according to claim 1, characterized in that the ends of the tubular jacket surface (12) have partial pieces that form thickenings (32, 40) and form a seat (35, 45) or a receptacle for the printing plate and that Thickenings (32, 40) are equal to the thickness of the pressure plate and the outer edges (33, 34) of these thickenings are rounded. 3. Printing cylinder, according to claim 2, characterized in that the two thickenings (32, 40) are achieved by machining the peripheral jacket (12). 4. Printing cylinder, according to claim 2, characterized in that the thickenings (32, 40) are achieved by applying material. 5. Printing cylinder, according to claim 4, characterized in that the material of the thickenings (32, 40) have coefficients of friction and abrasion resistance, which are similar to the material properties of the printing plate. 6. Printing cylinder, according to claim 4, characterized in that the material of the thickenings (32, 40) consists of the same photosensitive material which is applied to the printing plate. 7. Printing cylinder, according to one or more of claims 1-6, characterized in that the surface of the jacket (12) is continuous. 8. Printing cylinder, according to one or more of claims 1-6, characterized in that the surface of the jacket (12) has at least one longitudinal recess (50, 51, 52) or a longitudinal slot for receiving and fixing the connection joint of the printing plate. 9. Printing cylinder, according to claim 8, characterized in that the recess (50, 51, 52) extends along a surface line of the tubular shell (12). 10. Printing cylinder, according to claim 8, characterized in that the slot (50, 51, 52) is arranged inclined with respect to the surface line of the tubular shell (12). 11. Printing cylinder, according to claim 8 or 9, characterized in that the longitudinal slot (50) is arranged in the radial direction of the cylinder. 12. Printing cylinder, according to claim 11, characterized in that the depth of the slot (50, 52) is greater than its width. 13. Printing cylinder, according to claim 11, characterized in that the depth of the slot (51) is smaller than its width. 14. Printing cylinder, according to claim 11, characterized in that the slot (52) is inclined with respect to the radial direction of the casing (12). 15. Printing cylinder, according to one of the claims 1-14, characterized in that the jacket has additional slots (53, 54) of less depth than the slots for receiving the connecting joint. 16. Printing cylinder, according to claim 15, characterized in that also on the inner surface of the jacket (12) slots (58) are incorporated, which with the slots (56, 57) on the outer surface of the jacket (12) for bracing the foot joint Working together to widen the jacket (12).

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