EP2845731A1 - Impression roller - Google Patents

Abstract

Impression roller of a rotary printing machine with a cylinder which is more or less electrically conductive in at least one region, - Means for rotatably supporting the cylinder about its cylinder axis and at least one device for supplying an electrical voltage to the electrically conductive region, - An electrically conductive, coaxial to the cylinder shaft or axis and - Has at least one coaxial to the cylinder sliding ring of electrically conductive and flexible material which is slidably seated on the shaft or axle, wherein either the electrically conductive shaft is rotatably connected to the cylinder and is electrically connected to the electrically conductive region of the cylinder, the sliding ring is arranged stationary and can be connected to an electrical power supply, - Or the slip ring is rotatably connected to the cylinder and is electrically connected to the electrically conductive region and the axis is arranged stationary and can be connected to an electrical power supply.

Description

The invention relates to a impression roller of a rotary printing press.

In rotary printing, the sheet-shaped or sheet-shaped printing material (e.g., paper, cardboard, or plastic sheets) is passed at high speed between a pressure roller and a pressing roller. Particularly high speeds are achieved in commercial printing. The printing cylinder picks up ink from a paint pan in cells in its surface. The surplus is usually shaken off. In order to transfer the ink as far as possible from the cups of the printing cylinder lying electrically to ground onto the printing material, a more or less electrically conductive region of a cylindrical impression roller with a rubber-elastic outer layer is supplied with a high voltage. The electrically conductive region is e.g. around a semiconductor layer deposited on the circumference of a solid or hollow cylindrical body. As a result, an electric field forms between the electrically conductive region and the printing cylinder, which exerts a force on the ink in the cells, which intensifies the transition of the ink to the printing material and increases the print quality.

It is known to supply the impression roller with the electrical charge via a needle electrode (also called a "spray electrode"), which is spaced from the impression roller by an air gap. Furthermore, it is known to supply the impression roller with the electrical voltage via laterally arranged electrodes, brush grinding contacts or via the bearings.

From the EP 0 556 463 B1 For example, there is known an axleed impression roller having a limited conductive coating over a steel jacket. The coating is the electrical charges on the axis, a ball bearing between the axis and steel jacket and the steel jacket supplied. Furthermore, from this publication, a impression roller with a shaft and a limited conductive coating on a steel jacket known. The covering the electric charges are supplied via a arranged on the front side of the shaft ball bearing, the shaft and the steel shell.

The voltage supply via electrodes and brush grinding contacts is unreliable because of soiling and wear. The supply of ball bearings can be affected by the wear of the bearings, which can be accelerated by the supply of voltage.

From the EP 1 780 011 A1 For example, a pressure roller with a more reliable device for supplying an electrical voltage is known, which has a rotor connected to the cylinder and concentric with the cylinder axis and a stator spaced from the rotor concentric with the cylinder axis and a cavity between rotor and stator. A rotor electrode facing the cavity is connected to the electrically conductive region of the cylinder, and a stator electrode facing the cavity can be connected to an electrical power supply. In the cavity, an electrically conductive fluid is arranged. Means for preventing leakage of the electrically conductive fluid from the cavity are present. According to one embodiment, this is a sealing element which laterally delimits the cavity between the stator and the rotor, which may be designed in particular as a simmer ring.

The DE 20 2007 002 726 U1 describes a further impression roller with a more reliable device for supplying an electrical voltage, comprising an electrically conductive contact element in a device for guiding and a spring element for pressing the electrically conductive contact element against the Scope of the shaft or axle identifies. According to one embodiment, the contact element is a contact pin. According to a further embodiment, the means for supplying an electrical voltage comprises a stator, a rotor, a cavity between the stator and the rotor, in which the means for guiding with the contact element is arranged, an electrically conductive fluid in the cavity and means for preventing the outflow of the electrically conductive fluid from the cavity. The electrical voltage is transmitted from the electrically conductive contact element to the shaft or from the axis to the electrically conductive contact element. In addition, a voltage transfer between the stator and the rotor can be effected by the electrically conductive fluid. This is particularly advantageous when the electrically conductive contact element fails. Conversely, the electrically conductive contact element can transmit the electrical voltage when the voltage transmission is interrupted by the electrically conductive fluid.

Based on this, the present invention seeks to provide a impression roller with a device for supplying an electrical voltage, which works reliably with little effort.

The object is achieved by a impression roller with the features of claim 1.

• einen Zylinder, der zumindest in einem Bereich mehr oder weniger elektrisch leitfähig ist,
• Mittel zum drehbaren Lagern des Zylinders um seine Zylinderachse und
• mindestens eine Einrichtung zum Zuführen einer elektrischen Spannung an den elektrisch leitfähigen Bereich,
• die eine elektrisch leitfähige, zum Zylinder koaxiale Welle oder Achse und
• mindestens einen zum Zylinder koaxialen Gleitring aus elektrisch leitfähigem sowie flexiblem Material aufweist, der auf der Welle oder Achse gleitend aufsitzt,
• wobei die elektrisch leitfähige Welle drehfest mit dem Zylinder verbunden ist und elektrisch mit dem elektrisch leitfähigen Bereich des Zylinders verbunden ist, der Gleitring ortsfest angeordnet ist und mit einer elektrischen Spannungsversorgung verbindbar ist
• oder der Gleitring drehfest mit dem Zylinder verbunden ist und elektrisch mit dem elektrisch leitfähigen Bereich verbunden ist und die Achse ortsfest angeordnet ist und mit einer elektrischen Spannungsversorgung verbindbar ist.

The impression roller according to the invention has a rotary printing press

• a cylinder which is more or less electrically conductive in at least one region,
• Means for rotatably supporting the cylinder about its cylinder axis and
• at least one device for supplying an electrical voltage to the electrically conductive region,
• the one electrically conductive, coaxial to the cylinder shaft or axis and
• has at least one sliding ring of electrically conductive and flexible material, which is coaxial with the cylinder and slidably rests on the shaft or axle;
• wherein the electrically conductive shaft is rotatably connected to the cylinder and is electrically connected to the electrically conductive region of the cylinder, the sliding ring is arranged stationary and can be connected to an electrical power supply
• or the slip ring is rotatably connected to the cylinder and is electrically connected to the electrically conductive region and the axis is arranged stationary and can be connected to an electrical power supply.

In the impression roller according to the invention, the electrical voltage is supplied via at least one means for supplying an electrical voltage having an electrically conductive, coaxial to the cylinder shaft or axis and at least one coaxial to the cylinder sliding ring of electrically conductive and flexible material on the shaft or Axis slidably seated. If the impression roller has a shaft, this is non-rotatably connected to the cylinder and electrically connected to the electrically conductive region of the cylinder. The sliding ring is arranged stationary in this variant of the invention and connectable to an electrical power supply. The electrical voltage passes from the sliding ring on the rotating shaft and from the shaft to the electrically conductive material of the cylinder to form an electric field between impression roller and impression cylinder. If the impression roller has a stationary axis, the sliding ring is non-rotatably connected to the cylinder and electrically connected to the electrically conductive area. At this Invention variant, the stationary axis with the electrical power supply can be connected. Via the axis, the electrical voltage passes through the sliding ring rotating with the cylinder to the electrically conductive area on the circumference of the cylinder, so that the electric field is formed between impression roller and impression cylinder. This voltage supply is particularly inexpensive and works very reliable. In particular, the wear of the seal ring can be kept low because it can have a line contact or surface contact with the shaft or axis. If the sliding ring also serves as a seal for a fluid, its wear is also reduced by the lubricating effect of the fluid. In addition, the sliding ring can be realized by means of inexpensive standard components. Furthermore, the sliding ring can have self-adjusting properties, in particular if it consists of an elastic material. As a result, the sliding ring can compensate for wear. The means for rotatably supporting the cylinder are preferably insulated from the cylinder or from a frame or frame made of metal, so that the charge does not flow from the cylinder to the mass.

According to one embodiment, the sliding ring sits on the periphery and / or the end face of the shaft or axis. In particular, it can press in the radial direction against the circumference of the shaft or axis or press in the axial direction against the end face of the shaft or axis. The chosen construction can be made dependent on the structural conditions of the impression roller to be equipped with the device for supplying an electrical voltage.

The slip ring may be a complete circumferential ring or consist of one or more ring segments. When executed from one or more segments, it may also be referred to as a "segment ring".

The shaft or axle according to one embodiment is made of steel or another metal.

According to a further embodiment, the shaft or axle is polished at least in the region on which the sliding ring rests. As a result, the wear of the seal ring is reduced and improves the contact between the seal ring and shaft or axis.

The device for supplying an electrical voltage can be designed such that it contacts the shaft or axis solely via at least one sliding ring. According to a preferred embodiment, the means for supplying an electrical voltage comprises a stator or rotor arranged concentrically with the cylinder axis at a distance from the shaft or axis, a cavity between the shaft and the stator or the axis and the rotor, an electrically conductive fluid into the cavity and the at least one sliding ring seals the cavity on at least one side. This embodiment comprises a device for supplying an electrical voltage to a fluid transmission system, as for example in the DE 20 2005 016 974 U1 or the EP 1 780 011 A1 is described. The electrically conductive fluid is for example an oil or fat. A suitable electrically conductive roller bearing grease is offered, for example, by Klüber Lubrication München KG, Geisenhauerstrasse 7, 8379 Munich, Germany, under the trade name Klüberlektrik B42-72. The slip ring ensures the supply of electrical voltage, if the transmission by means of the electrically conductive fluid is ineffective, for example, because the fluid has leaked out of the cavity.

The stator is preferably circular-cylindrical, if the voltage is transmitted via the electrically conductive fluid to the circumference of the shaft. Accordingly is the rotor is preferably circular cylindrical when the voltage is transmitted to the circumference of the axis. In these cases, the cavity between the stator and the rotor is preferably sealed by sliding rings at both ends of the cavity. If the voltage is transmitted to a circular disk-shaped end face of the shaft, the stator is preferably likewise circular disk-shaped. If the voltage is transmitted to a circular disk-shaped end face of the axle, so also the rotor is preferably designed circular disk-shaped. In these cases, the cavity between shaft or axle and stator or rotor may be sealed externally by a single slip ring. In all the cases mentioned, a plurality of sliding rings can also be arranged directly next to one another in order to seal the cavity on one side several times, to ensure the supply of the electrical voltage in order to reduce the contact resistance.

According to a preferred embodiment, the sliding ring is a Simmerring of electrically conductive and flexible material. Simmerrings with the aforementioned properties are available. They are formed for example of Teflon or other plastic with graphite, carbon fiber or soot deposits. Suitable Simmerringe are for example offered by the company ... under the trade name ....

According to another embodiment, the sliding ring is a stuffing box ring made of an electrically conductive and flexible material. Stuffing box rings with the mentioned properties are available. These are, for example, stuffing box rings of Teflon or another plastic with deposits of graphite, carbon fibers or carbon black.

According to a preferred embodiment, the sliding ring consists of an elastic material, so that it has self-adjusting properties.

In a stuffing box ring readjustment can also be effected by a spring element which permanently presses the stuffing box ring against the shaft or axle. Accordingly, an adjustment by a spring element can be effected even with a Simmerring.

According to one embodiment, the shaft, on which the sliding ring is seated, supports the impression roller in a stationary pivot bearing. The shaft for supporting the impression roller is then used at the same time as a contact element for the sliding ring. In this The pivot bearing is arranged according to an embodiment in a frame or frame electrically isolated.

According to another embodiment, the shaft on which the sliding ring is seated, a non-rotatably connected to the end face of the cylinder shaft which is arranged concentrically to a shaft or axis for supporting the cylinder. This arrangement can be selected in a press roller with a shaft for supporting the impression roller, if for structural reasons, the slide ring can not be placed on the shaft for supporting the impression roller. Furthermore, the shaft rotatably connected to the end face of the cylinder can be provided when the impression roller is mounted on an axle. For this purpose, pivot bearings are arranged between cylinder and axle. Preferably, the pivot bearing relative to the axis or the axis with respect to a frame or frame for storing the impression are insulated so that the charge does not flow from the cylinder to ground.

According to a further embodiment, the sliding ring is embedded on the circumference in a retaining ring or clamped between a stop on one side and a mounting ring on the other side or between the mounting ring on both sides. As a result, the sliding ring can be fixed with a defined preload. According to one embodiment, a plurality of juxtaposed seal rings sitting on the shaft or axis. As a result, the risk of failure of the voltage supply can be avoided, since a multiple security for the voltage transmission is achieved. In addition, this can reduce the contact resistance and improve the charge supply.

According to a further embodiment, the shaft, on which the sliding ring is seated, is hollow cylindrical. This embodiment can be selected, for example, when a shaft rotatably connected to the end face of the cylinder is arranged concentrically to a shaft or axis for supporting the cylinder. Furthermore, according to a further embodiment, a rotary feedthrough for compressed air can be extended through the hollow cylindrical shaft. Herein, the hollow cylindrical shaft can be arranged on the end face of a shaft for supporting the cylinder. The rotary feedthrough in a sleeve system is used to inflate the sheath of the impression roller by means of compressed air in order to exchange it for another sheath.

Fig. 1

einen Presseur mit einer Welle, einem Drehlager und einer Einrichtung zum Zuführen einer elektrischen Spannung mit einem die Welle umgebenden Stator und auf dem Umfang der Welle sitzenden Simmeringen eines Fluidübertragungssystems im teilweisen Längsschnitt;

Fig. 2

einen Presseur mit einer Welle und einer Einrichtung zum Zuführen einer elektrischen Spannung mit einer die Welle umgebenden Stator und einem auf dem Umfang der Welle aufsitzenden Simmerring im teilweisen Längsschnitt;

Fig. 3

einen Presseur mit einer Welle und einer Einrichtung zum Zuführen einer elektrischen Spannung mit einem die Welle umgebenden Stator und einer Gruppe auf dem Umfang der Welle aufsitzenden Simmerringen im teilweisen Längsschnitt;

Fig. 4

einen Presseur mit einer Welle und einer Einrichtung zum Zuführen einer elektrischen Spannung mit einem an der Stirnseite der Welle befestigten Rotor, einem den Rotor umgebenden Stator und einem auf dem Umfang des Rotors aufsitzendem Simmerring und einer Drehdurchführung für Druckluft im teilweisen Längsschnitt;

Fig. 5

einen Presseur mit einer Welle und einer Einrichtung zum Zuführen einer elektrischen Spannung mit einem an der Stirnseite der Welle befestigten Rotor, einem diesen umgebenden Stator und auf dem Rotor aufsitzenden Simmerringen und einem elektrisch leitfähigen Fluid im teilweisen Längsschnitt.

The invention will be explained in more detail with reference to the accompanying drawings of exemplary embodiments. In the drawings show:

Fig. 1

a impression roller with a shaft, a pivot bearing and a device for supplying an electrical voltage with a stator surrounding the shaft and seated on the circumference of the shaft Simmeringen a fluid transmission system in partial longitudinal section;

Fig. 2

a impression roller with a shaft and a device for supplying an electrical voltage with a stator surrounding the shaft and a Simmerring seated on the circumference of the shaft in partial longitudinal section;

Fig. 3

a Pressur with a shaft and means for supplying an electrical voltage with a stator surrounding the shaft and a group on the circumference of the shaft seated Simmerringen in partial longitudinal section;

Fig. 4

a Pressur with a shaft and means for supplying an electrical voltage with a rotor attached to the end of the shaft, a stator surrounding the rotor and a seated on the periphery of the rotor Simmerring and a rotary feedthrough for compressed air in the partial longitudinal section;

Fig. 5

a impression roller with a shaft and means for supplying an electrical voltage with a rotor attached to the end face of the shaft, a stator surrounding it and Simmerringen seated on the rotor and an electrically conductive fluid in the partial longitudinal section.

In the following explanation of various exemplary embodiments, matching or essentially matching components are designated by the same reference numerals, differences being characterized by a following point and different numbers behind the point.

According to Fig. 1 has a impression roller 1.1 a cylinder 2, which has a metallic cylinder core 3 and a rubber-elastic, electrically semiconducting layer 4 on the outer circumference. The layer 4 consists for example of rubber with embedded carbon black, carbon fiber or graphite particles. Further, the impression roller 1 has a fixed to the cylinder core 3 shaft 5 made of steel, which is mounted on both sides in pivot bearings in the form of radial ball bearings 6. The ball bearings 6 are supported on the one hand on a radial shoulder of the shaft 5 and on the other hand secured to a snap ring inserted into a groove of the shaft against axial displacement. The ball bearings 6 are mounted outside in bearing shells 7 of electrically insulating material and the bearing shells 7 in a bearing shell support 8, which is connected to a machine frame, not shown. The bearing shells 7 have a flange 7.1 at one end of a cylindrical section 7.2.

The circumference of the shaft 5 is associated with a device for supplying an electrical voltage 9.1. This has an inside circular cylindrical stator 10 which is fixed on the side of the cylinder core 3 by means not shown screws on the bearing shell carrier 8. Inside, the stator 10 has two circular-cylindrical sections 10.1, 10.2, between which a diameter jump 10.3 is present. The section 10.2 has a larger diameter than the section 10.1 and in between a diameter jump 10.3 is present.

In the circular cylindrical section 10.1 with the large diameter sits another insulating bearing shell 11, which extends partially into the adjacent bearing shell 7 inside. The further bearing shell 11 rests with a further flange 11.1 on the diameter jump 10.3. The flange 11.1 is arranged at the end of a cylindrical portion 11.2.

On the inner circumference of the cylindrical portion 11.2 are a Simmerring 12 of electrically conductive material, which is seated inside the circumference of the shaft 5, an electrically conductive ring 13, e.g. made of metal, which has a small distance from the shaft, and another Simmerring 14 of electrically conductive material, which rests on the inside of the circumference of the shaft 5, arranged. This arrangement is supported on the other side on a coaxial to the shaft 5, circular cylindrical support portion 15.1 on the side of a support plate 15.2, which is supported on the other side on the pivot bearing 6. By screwing the stator with the bearing cup carrier, the shaft bearing and the Simmerringe and the metal ring are secured in the positions shown.

Between the electrically conductive ring 13, the Simmerringen 12, 14 and the circumference of the shaft 5, a cavity 16 is present, which is filled with an electrically conductive grease.

The stator 10 has a radial insertion hole 17 for an electrical connector 18 of an electrical power supply. The further bearing shell 11 and the ring 13 thus have aligned insertion holes 19, 20. The insertion holes 19, 20 of the further bearing shell 11 and the ring 13 are dimensioned so that an end-side pin 21 of the connector 18 is clamped inserted. The pin 21 can be equipped for good contact with resilient segments.

From the electrical power supply, an electrical voltage is supplied to the ring 13 of electrically conductive material via the connector 18. From the ring 13, the voltage passes through the Simmerringe 12, 14 and the electrically conductive grease to the circumference of the shaft 5. By the shaft 5, the voltage on the cylinder core 3 is forwarded to the layer 4 of the impression roller 1.1.

The execution of Fig. 2 differs from the above-described in that the means for supplying an electrical voltage 9.2 only has a Simmerring 14. Thus, the applied by means of the connector 18 to the ring 13 voltage of a power supply is transmitted through the electrically conductive Simmerring 14 on the circumference of the shaft 5 and from there via the cylinder core 3 on the outer layer 4 of the impression 1.2. This embodiment has no cavity with an electrically conductive fluid.

The impression roller 1.3 of Fig. 3 differs from the above-described characterized in that the means for supplying an electrical voltage 9.3 three juxtaposed Simmerringe 14.1, 14.2, 14.3 made of electrically conductive material. Between adjacent Simmerrings 14.1, 14.2, 14.3 spacer rings 22.1, 22.2 are arranged. The spacers 22.1, 22.2 are also made of metal or other electrically conductive material.

An introduced by means of the connector 18 of a high voltage power supply and the ring 13 voltage is transmitted via the spacers 22.1, 22.2 and Simmerringe 14.1, 14.2, 14.3 to the circumference of the shaft 5 and passes from there via the cylinder core 3 to the shell 4 of the impression 1.3. Optionally, the cavities 16.1, 16.2 can be filled between the Simmerrings with an electrically conductive fluid. In this way, if appropriate, the life of the Simmerringe 14.1, 14.2, 14.3 be increased because the fluid causes lubrication, which can reduce the wear of the Simmerringe.

In the execution of Fig. 4 the shaft 5 of a impression roller 1.4 is mounted in radial ball bearings 6, which are supported via an insulating bearing shell 7 in a machine frame, not shown. The shaft 5 has a central Tapped hole 24 for supplying compressed air for the purpose of replacing a sleeve sleeve on the casing of the impression roller 1.4.

A rotary feedthrough 25 for supplying compressed air is screwed into the threaded bore 24 in the end face of the shaft 5.

Further, a rotor 26 is screwed with a hollow cylindrical portion 26.1 and a flange 26.2 at one end by means of screws 27 to the end face of the shaft 5. The rotor 26 is made of an electrically conductive material, in particular of steel.

The hollow cylindrical section 26. 1 of the rotor 26 is surrounded by a substantially circular cylindrical stator 10. The stator 10 is made of an electrically insulating material. It is fixed by screws 27 on a machine frame fixed mounting plate.

In the stator 10, a metallic ring 13 is used, which is fixed on the inner circumference of the stator 10 by means not shown. The stator 10 and the ring 13 have aligned insertion holes 17, 20 into which a connector 18 is inserted with a contact pin 21.

Between the ring 13 and the mounting plate 28, a Simmerring 14 is clamped from electrically conductive material. The Simmerring 14 has a rigid, L-shaped base 29.1, wherein on the leg perpendicular to the shaft of the base an elastically deformable portion 29.2 of the Simmerringes 14 is fixed in acute-angled alignment with this leg. The cavity 16 between the ring 13 and the Simmerring 14 may also be filled with an electrically conductive fluid.

A supplied by a connector 18 from a high voltage supply voltage is introduced into the metallic ring 13 and passes through the Simmerring 14 and optionally the electrically conductive fluid on the mantle of the cylindrical portion 26.1 of the rotor 26th

From the rotor 26, the voltage passes through the shaft 5 and the cylinder core to the jacket of the impression roller 1.4.

The impressioner 1.5 of Fig. 5 differs from the above-described characterized in that on the inner circumference of the stator 10 on the two sides of the ring 13 each have a Simmerring 29 is arranged made of electrically conductive material. The additional Simmerring 29 is supported on the one hand on the flange of the stator 10 and on the other hand on the ring 13 from.

Claims (14)

Impression roller of a rotary printing machine with a cylinder (2) which is more or less electrically conductive in at least one region (4), - Means for rotatably supporting (6) of the cylinder about its cylinder axis and at least one device for supplying an electrical voltage (9) to the electrically conductive region (4), - An electrically conductive, the cylinder (2) coaxial shaft (5) or axis and - Has at least one to the cylinder (2) coaxial sliding ring (12, 14, 29) of electrically conductive and flexible material which is slidably mounted on the shaft (5) or axis, - Wherein either the electrically conductive shaft (5) rotatably connected to the cylinder (2) and is electrically connected to the electrically conductive portion of the cylinder (2), the sliding ring (12, 14, 29) is arranged stationary and with an electrical Power supply is connectable, - Or the slide ring (12, 14, 29) rotatably connected to the cylinder (2) and is electrically connected to the electrically conductive region (4) and the axis is arranged stationary and can be connected to an electrical power supply. A blank according to claim 1, wherein the sliding ring (12, 14, 29) rests on the circumference and / or the end face of the shaft (5) or axle. A blank according to claim 1 or 2, wherein the shaft (5) or axle is made of steel. A compression spring according to any one of claims 1 to 3, wherein the shaft (5) or axle is polished at least in the region against which the sliding ring (12, 14, 29) rests. A blank according to any one of claims 1 to 4, wherein the means for supplying an electric voltage (9) comprises a stator (10) or rotor (26) arranged at a distance from the shaft (5) or axis concentric to the cylinder axis and a cavity (16 ) between the shaft (5) and the stator (10) or the axis and the rotor (26), an electrically conductive fluid in the cavity (16) and the at least one sliding ring (12, 24, 29) the cavity ( 26) on at least one side seals. A compression spring according to any one of claims 1 to 5, wherein the sliding ring (12, 14, 29) is a Simmerring of electrically conductive and flexible material. A blank according to any one of claims 1 to 5, wherein the sliding ring is a stuffing box ring made of an electrically conductive and flexible material. A blank according to any one of claims 1 to 7, wherein the sliding ring (12, 14, 29) consists of an elastic material. Pressurizer according to one of claims 1 to 8, in which the shaft (5) on which the sliding ring (12, 14, 29) is seated, supports the impression roller in a stationary rotary bearing (6). Compression blanket according to one of Claims 1 to 8, in which the shaft on which the sliding ring (12, 14, 29) is seated is a shaft which is non-rotatably connected to the end face of the cylinder (2) and which is concentric with a shaft (5) or Axle is arranged for supporting the cylinder. A blank according to any one of claims 1 to 10, wherein the sliding ring (12, 14, 29) is embedded in a retaining ring circumferentially or between a stop on one side and a mounting ring on the other side or between mounting rings (22) on both sides is clamped. A blank according to any one of claims 1 to 11, wherein a plurality of juxtaposed sliding rings (12, 14, 29) rest on the shaft (5) or axle. A blank according to any one of claims 1 to 12, wherein the shaft on which the sliding ring (12, 14, 29) is seated is hollow cylindrical. A compression spring according to claim 14, in which a rotary feedthrough (25) for compressed air is passed through the hollow cylindrical shaft (5).

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