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EP-4400315-B1 - SEALING SYSTEM

EP4400315B1EP 4400315 B1EP4400315 B1EP 4400315B1EP-4400315-B1

Inventors

  • RUDOLPH, FRANK

Dates

Publication Date
20260506
Application Date
20230110

Claims (11)

  1. A sealing system, the sealing system comprising two first sealing members (62) which are each disposed at opposite lateral ends (56) of a doctor blade chamber (48) which in operational mode is adapted to partially receive a rotatable roller (46) for applying ink from the doctor blade chamber (48) onto the roller (46), and two second sealing members (64) which are each disposed at opposite lateral ends (60) of the rotatable roller (46) which in operational mode is configured to extend partially into the doctor blade chamber (48) for receiving ink from the doctor blade chamber (48), wherein in operational mode, each of the two first sealing members (62) is in rotating contact with each of the two second sealing members (64) such that a leakage of ink at the opposite lateral ends (56) of the doctor blade chamber (48) is prevented.
  2. The sealing system according to claim 1, wherein each of the two first sealing members (62) is formed as a semicircle shaped bearing, each bearing has a curvature which corresponds to a curvature of a perimeter (58) of the rotatable roller (46).
  3. The sealing system according to claim 1 or 2, wherein each of the two first sealing members (62) is a lip seal.
  4. The sealing system according to any one of the preceding claims, wherein each of two second sealing members (64) is ring-shaped and extends continuously around the perimeter (58) of the rotatable roller (46).
  5. The sealing system according to any one of the preceding claims, wherein each of the two second sealing members (64) is made from a harder material as each of the two first sealing members (62).
  6. The sealing system according to any one of claims 1 to 4, wherein each of the two first sealing members (62) is made from a harder material as each of the two second sealing members (64).
  7. The sealing system according to any one of the preceding claims, wherein each of two the first sealing members (62) is made from a material which is selected from the group consisting of ethylene propylene diene monomer rubber, polyvinylidene fluoride, fleece, polished steel or an alloy, thermoplastic polymer and a combination thereof.
  8. The sealing system according to any one of the preceding claims, wherein the system further comprises a lubrication unit (66) which is adapted to lubricate a contact surface between each of the two first sealing members (62) and each the two second sealing members (64) with a lubricant.
  9. The sealing system according to claim 10, wherein the lubrication unit (66) has a reservoir unit (68) in which a lubricant is stored which is selected from the group consisting of mineral oil and synthetic oil, wherein the lubrication unit (66) further comprises a pump (70) assigned to the reservoir unit (68), the reservoir unit (68) being fluidly connected to at least one lubrication channel (72), the at least one lubrication channel (72) extending from the reservoir unit (68) towards a dispenser unit (74) which is assigned to the contact surface (76) of each of the two first sealing members (62) and each of the two second sealing members (64).
  10. The sealing system according to claim 10, wherein the lubrication unit (66) has a compressed gas unit (78) in which pressurized gas is stored, wherein the lubrication unit (66) further comprises a gas channel (80) and a nozzle (82) which are fluidly connected to each other, and wherein the compressed gas unit (78) is adapted to provide a gaseous lubricant between each of the two first sealing members (62) and each the two second sealing members (64) such that in operation mode each of the two first sealing members (62) and each the two second sealing members (64) are separated by a layer of gas.
  11. The sealing system according to claim 10 wherein the gaseous lubricant is selected from the group of argon, air, nitrogen and mixtures thereof.

Description

The invention relates to a sealing system for a doctor blade assembly of a rotary printing press. A typical doctor blade assembly used in a conventional rotary printing press accommodates a rotatable roller which picks up ink from a reservoir and deposits the ink onto another surface located opposite to the reservoir. Typically, the other surface is an anilox cylinder which subsequently transfers the ink to a plate cylinder on which a flexo plate is fixedly mounted. From the flexo plate, the ink is finally transferred to a substrate which is partially in contact with the perimeter of the plate cylinder. Such an assembly is also known as a printing unit. In a conventional rotary printing press, a plurality of printing units is arranged around a perimeter of a central cylinder and around which a substrate in the form of a long web is guided along a substrate handling path. The substrate is printed with ink while being moved along the printing handling path from an unwinder to a winder station. Hereby, the doctor blade assembly plays a crucial role in transferring ink from the reservoir to the rotatable roller. In order to prevent a leakage of ink between the reservoir filled with ink and the rotatable rotating roller, it is essential to provide a sealing to seal the opposite ends of the reservoir from the rotating roller. There are different attempts known in the prior art to seal a doctor blade assembly. For example, EP 2 425 972 B1 describes an end seal for removable attachment to a doctor blade assembly which inhibits seal failure due to unintended seal movement. In detail, a pair of seals is exclusively attached to the housing of the doctor blade. Another sealing is known from the DE 202 01 901 U1, the sealing for a doctor blade assembly is a rubber which is held at the opposite ends of the doctor blade chamber. A further sealing is known from EP 2 821 228 B1. The document discloses a seal for a doctor blade device rotary printing press comprising a doctor blade contacting section with a front side engaged with a doctor blade of the doctor blade device and a rear side that is softer, more elastic or more resilient than the front side. Another sealing is known from DE 20 2009 013643 U1. The document discloses a sealing element for front-side sealing of an inner chamber of a chambered doctor blade system in a color deck of a flexographic printing machine, having sealing part formed as insert that is made of hard material with self-lubricating effect. However, sealings used in doctor blade assemblies are subject to uncontrolled deformation and severe wear since the sealing is during the operational mode of the press always in rotating contact with the rotatable roller. Thus, existing doctor blade assemblies often suffer from unintended ink leakage due to severe wear of the sealings. Furthermore, there are a myriad of sealing systems available on the market, so that not every sealing of a doctor blade chamber is suitable for each and every roller. It is therefore an object of the present invention to provide a sealing system for a doctor blade assembly that overcomes at least one of the aforementioned disadvantages of the prior art. This objective is achieved by a sealing system according to claim 1, the sealing system comprising two first sealing members which are disposed at opposite lateral ends of a doctor blade chamber which in operational mode is adapted to partially receive a rotatable roller for applying ink from the doctor blade chamber onto the roller. The sealing system further comprises two second sealing members which are each disposed at opposite lateral ends of the rotatable roller, which in operational mode is configured to extend partially into the doctor blade for receiving ink from the doctor blade chamber. In an operational mode, each of the two first sealing members is in rotating contact with each of the two second sealing members such that a leakage of ink at opposite lateral ends of the doctor blade chamber is prevented. The basic idea of the invention is to provide two separate sealings instead of one single sealing, as known in the prior art. Typically, sealing systems for doctor blade assemblies are using merely a single sealing which is either disposed on the rotating roller or disposed on the doctor blade chamber. This often leads to an undesired severe wear of the single sealing. This issue is solved by the invention by using a two-part system, in which one part of the sealing is assigned to a doctor blade assembly and the other corresponding part of the sealing is assigned to the rotatable roller. By using two sealings, improved sealing properties of the doctor blade assembly can be achieved. Furthermore, the wear of the sealings is distributed between the two sealings such that the wear is reduced in general. As a result, a doctor blade assembly having a sealing system according to the invention has a longer running time compared to doctor blade assembles with prior art sealing