EP1347095A1 - Indexsystem für die Walzendeckel einer Schuhpresse - Google Patents

Indexsystem für die Walzendeckel einer Schuhpresse Download PDF

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Publication number
EP1347095A1
EP1347095A1 EP02252072A EP02252072A EP1347095A1 EP 1347095 A1 EP1347095 A1 EP 1347095A1 EP 02252072 A EP02252072 A EP 02252072A EP 02252072 A EP02252072 A EP 02252072A EP 1347095 A1 EP1347095 A1 EP 1347095A1
Authority
EP
European Patent Office
Prior art keywords
blanket
heads
press
shoe
backing roll
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02252072A
Other languages
English (en)
French (fr)
Inventor
Mark Anthony Porter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sandusky Walmsley Ltd
Original Assignee
Sandusky Walmsley Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sandusky Walmsley Ltd filed Critical Sandusky Walmsley Ltd
Priority to EP02252072A priority Critical patent/EP1347095A1/de
Publication of EP1347095A1 publication Critical patent/EP1347095A1/de
Withdrawn legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F3/00—Press section of machines for making continuous webs of paper
    • D21F3/02—Wet presses
    • D21F3/0209—Wet presses with extended press nip
    • D21F3/0218—Shoe presses

Definitions

  • This invention concerns a system for applying axial tension to a blanket in a shoe press of a papermaking machine.
  • an elongate shoe having a concave surface forms a nip with a backing roll. This lengthens the duration of contact with a paper web passing through the nip to allow more water to pass from the web into one or more supporting felts, as required in modern high speed presses where the paper web may be travelling at something in the order of 15m/sec.
  • a blanket in the form of a seamless tube is passed over the shoe.
  • the blanket is lubricated and cooled by a supply of oil or other lubricant which is forced between the blanket and the shoe.
  • the blanket is sealed at each end to a respective head.
  • the heads referred to as front and back heads, each have an outer portion (termed an outer head) which is circular and is mounted for rotation on a journal of a support beam, which also supports the shoe and a hydraulic piston which urges the shoe towards the backing roll.
  • the blanket As the blanket is caused to move through the nip, by virtue of frictional engagement with the paper web, any supporting felt, and the backing roll, it assumes a dimpled shape (rather like an apple) in cross section in conformity with the concave shoe. However, the blanket extends beyond each end of the shoe to attach to the circular outer heads. The transition from the dimpled shape to the circular shape means that in the region adjacent each end the blanket undergoes repeated changes in curvature, resulting in wear and eventual failure. This can be a significant source of maintenance down time and contributor to the cost of the papermaking process.
  • the motion of the blanket through the nip also results in gradual lengthening of the blanket in the cross machine direction owing to its continual compression. In this respect, over a period of about 6 months, it can stretch or lengthen by something of the order of 15 to 20cm. To some extent this can be accommodated by an indexing system comprising hydraulic piston and cylinder assemblies which are mounted between the support beam and each head to apply tension to the heads. Periodically, however, the blanket has to be trimmed, which involves releasing it from the heads and refixing. This may result in 6 to 8 hours downtime.
  • the indexing system serves the further purpose, of course, of keeping the blanket shape stable as it rotates during operation of the press, preventing creasing and twisting as it passes through the nip.
  • An object of the invention is to provide an alternative, improved system of head indexing in a shoe press of the type described above, whereby the life of the blanket may be increased.
  • the invention provides a method of applying axial tension to a blanket in a shoe press of a papermaking machine which is characterised in that both heads are permanently floating and axial pressure applied thereto is controlled such that the blanket maintains a substantially central position on the press and elongation of the blanket during operation of the press is taken up substantially equally by the first and second heads.
  • the apparatus of the shoe press includes respective fluid actuated piston and cylinder assemblies mounted inside the blanket and operative to apply axial pressure to the first and second heads, thereby to tension the blanket, characterised in that the respective fluid assemblies include respective displacement sensors whereby the positions of the heads, and thereby of the blanket, relative to the press can be determined and monitored, and in that means are provided whereby automatic adjustments are then made to the positions of the heads to maintain the blanket in a substantially central position on the press.
  • the heads are limited in travel by the stroke of their respective cylinders. No other mechanical means of limiting the travel of the heads needs to be provided.
  • front and back heads 10, 12 are mounted onto press journals 14, 16 in such a way as to allow them to slide along the axis of the press approximately 10cm each.
  • Hydraulic cylinders 11, 13 are mounted to the heads 10, 12 to control axial movement of the heads.
  • the cylinders 11, 13 are mounted by way of brackets onto a central support beam (17) for an elongate shoe 15 having a concave surface.
  • the blanket which encircles the shoe 15 and its support beam and is, in use, sealingly clamped between the respective heads 10, 12 is not shown for the sake of clarity.
  • the cylinders 11, 13 are enclosed within the blanket, but are supplied with fluid via lines 20, 22 which are shown schematically in Figure 1, but in practice they would extend through the heads 10, 12. These lines 20, 22 connect via respective proportional control valves 21, 23, to a common hydraulic unit 24.
  • the cylinders 11, 13 are fitted with integral electronic displacement transducers which enable the exact extension of their respective pistons to be measured by the electronic control system 26 of the machine.
  • the machine control system 26 is shown schematically in Figure 1 along with electrical connections therefrom 31, 32 to transducers and 33, 34 to the proportional control valves 21, 23.
  • both sets of cylinders 11, 13 simultaneously, with fluid pressure to each cylinder being controlled by the machine control system 26 to maintain a substantially constant predetermined tension on the blanket.
  • Both heads 10, 12 will be permanently floating (i.e. not fixed in position by any external mechanical means) and the stretch of the blanket will be taken up equally at the front and back heads 10, 12.
  • the axial displacement of the respective heads 10, 12 will be limited only by the stroke of the respective cylinder pistons, which will be similar to the maximum possible sliding adjustment of the heads (i.e. about 10cm each, as mentioned).
  • the machine control system 26 will, by way of connections 31, 32, continuously monitor the amount of extension of the blanket at the front and back side of the press. With this information it is possible to determine the position of the blanket relative to the press by a simple calculation within the machine control system 26. Once the position of the blanket is known to the control system, the system can automatically adjust pressure, via signals to the control valves 21, 23, to either the front or back cylinders 11, 13 to move the blanket in an axial direction to centralize it in relation to the press. In this way, it is possible in accordance with the invention to maintain the centre line of the blanket in line with the centre line of the press. It is not intended to force any oscillation of the blanket in the axial direction. However the nature of this system will result in a small oscillation as the system tries to maintain the blanket position.

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  • Paper (AREA)
EP02252072A 2002-03-22 2002-03-22 Indexsystem für die Walzendeckel einer Schuhpresse Withdrawn EP1347095A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP02252072A EP1347095A1 (de) 2002-03-22 2002-03-22 Indexsystem für die Walzendeckel einer Schuhpresse

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP02252072A EP1347095A1 (de) 2002-03-22 2002-03-22 Indexsystem für die Walzendeckel einer Schuhpresse

Publications (1)

Publication Number Publication Date
EP1347095A1 true EP1347095A1 (de) 2003-09-24

Family

ID=27771952

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02252072A Withdrawn EP1347095A1 (de) 2002-03-22 2002-03-22 Indexsystem für die Walzendeckel einer Schuhpresse

Country Status (1)

Country Link
EP (1) EP1347095A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106481653A (zh) * 2015-08-25 2017-03-08 丰光机械株式会社 柔性加压辊

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5643416A (en) * 1996-06-07 1997-07-01 Beloit Technologies, Inc. Extended nip press with oscillating blanket for extended wear
US5775564A (en) * 1996-10-25 1998-07-07 Valmet Corporation Method and apparatus for reducing wear of a belt mantle of an extended-nip roll

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5643416A (en) * 1996-06-07 1997-07-01 Beloit Technologies, Inc. Extended nip press with oscillating blanket for extended wear
US5775564A (en) * 1996-10-25 1998-07-07 Valmet Corporation Method and apparatus for reducing wear of a belt mantle of an extended-nip roll

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106481653A (zh) * 2015-08-25 2017-03-08 丰光机械株式会社 柔性加压辊

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