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

• the present invention relates to a shoe press for a paper or board machine, comprising a press shoe and a counter roll, which between themselves form an extended nip for a paper or cardboard web and a circulated flex- ible belt, a plurality of hydraulic loading cylinders which are arranged between a horizontal beam included in the frame system of the shoe press and the press shoe and adapted to press the press shoe against the counter roll, the respective pistons of said loading cylinders being fixedly connected to the horizontal beam, the respective working chambers of the loading cylinders, being, for supplying the loading cylinders with hydraulic fluid, connected by means of a vertical duct formed in the piston of the loading cylinders, to a horizontal feeding duct extending in the shoe press in the machine direction and being common to all the working chambers.
• Such shoe presses are disclosed in, for instance, EP-345 501 B2; DE-195 15 832 Cl and DE-44 09 316 Cl.
• the working chamber in the loading cylinders in these prior-art shoe presses are pressurised by hydraulic fluid via ducts bored in the frame system of the shoe press. Boring the frame system, in most cases consisting of steel beams, in a shoe press for pressurising by hydraulic fluid is a complicated and expensive proce- dure and causes weakening of the beam, such that this is deflected more easily, which results in, inter alia, deformation of the duct.
• the shoe press described by way of introduction has the inventive features that the hori- zontal duct extends through the piston of the loading cylinders .
• Boring the pistons of the loading cylinders is essentially easier than boring the frame system of the shoe press, and moreover the frame of the shoe press need not be formed with weakening ducts for supplying the loading cylinders with hydraulic fluid.
• the additional advantage is obtained that the feeding duct can be manufactured in a particularly simple manner, for instance by extruding aluminium.
• Extrusion of aluminium allows the manufacture of bars in optional lengths for supplying an arbitrary number of loading cylinders.
• Such a bar also allows simple, easily accessible and easily releasable connection of the loading cylinders to the horizontal beam.
• the bar with the horizontal duct and the loading cylinders constitute a movable unit. According to claim 6, this idea is used to move the loading cylinders in the machine direction of the paper machine, thereby making it possible to vary the pressure profile on the paper/cardboard web in the nip, said variation in turn allowing optimum pressing of different paper/cardboard qualities.
• a particularly simple eccentric arrange- ment is stated in claim 7.
• a special advantage of this arrangement is that it allows freedom of choice for connecting the hydraulic fluid source to the horizontal duct, more precisely in one of the pipes connecting the bores, which connection can be easily carried out by means of conventional coupling elements.
• a special simple connection of the bores of the pistons and the pipes is achieved, according to claim 5, by easy insertion of the pipe ends, provided with seals in the bores. This results in a certain amount of flexibility in the connection and independence of heat expansion and deflection of horizontal beam of the frame.
• Fig. 1 is a cross-sectional view of a non-limiting embodiment of the invention in the machine direction
• Fig. 2 is a cross-sectional view of another embodiment in the cross-direction
• Fig. 3 is a cross-sectional view of the second embodiment in the cross-direction
• Fig. 4 is a top plan view of an eccentric plate, section IV-IV in Fig. 2.
• the press shoe is made in one piece, while the loading cylinders which are several in number, are distributed in the longitudinal direction of the press shoe (in the cross-direction) in one row or in several rows spaced from each other in the machine direction.
• the Figure shows a shoe press for the press section of a paper or board machine, said machine comprising the conventional shoe press components press shoe 1, counter roll 2 having the direction of rotation R, which between themselves form an extended nip N, in which a paper or cardboard web which is to be dewatered runs together with a circulated flexible press belt 3 and one or two press felts F, of which one is shown.
• a horizontal beam 4 associated with the frame system 5 of the shoe press has, between its side facing the press shoe and its side facing away from the press shoe, a plurality of loading cylinders 6 arranged in a row in the longitudinal direc- tion of the press shoe and having a cylinder part 7 and a piston 8, the latter being fixed to the beam 4 in a manner that will be described in more detail below.
• the press shoe 1 is in this case loosely arranged on the loading cylinder part 7, which can have, in a manner known per se, a hydrostatic compartment in its surface facing the press shoe for floatingly supporting the press shoe.
• a horizontal duct 9 which is formed in the longitudinal direction of the shoe (cross-direction) and adapted to supply the working chamber 10 of the loading cylinders with hydraulic fluid, e.g. oil, via a vertical duct 11 in the piston 8, the duct 9 being common to the working chamber of all loading cylinders, while there is a vertical duct 11 for each working chamber, connecting the common duct 9 with the working chamber.
• An O-seal 12 seals between the piston 8 and the cylinder part 7. Reference is once more made to Fig. 1.
• the common duct 9 is formed in a separate horizontal bar 14, and the vertical ducts 11 consist of two vertical duct parts 11' and 11", the duct part 11' being bored through the wall of the bar to the duct 9 in the bar, and the duct part 11" is bored in the piston 8.
• vertical ducts 11' can be bored in advance in the bar 14 and be sealed to be use later, if, for instance, further loading cylinders 6 are to be mounted, or be bored only on such occasions.
• the bar 14 forms part of all pistons 8, screws 15 providing for connection of the piston parts.
• the bar is made of aluminium (alloy) which can be extruded to obtain the desired section of the bar 14 and the desired diameter of the common duct 9.
• a space for an O-seal 11'" is formed in the end of these ducts 11'.
• the duct 9 is supplied with hydraulic fluid from a source (not shown) at one of its ends.
• FIG. 2 and 3 A further possibility of commonly supplying a plurality of loading cylinders 6 is shown in Figs 2 and 3, where a shoe press with a plurality of loading cylinders 6 arranged in a row is indicated, two being shown.
• the common horizontal duct 9 is formed of bores 9' in the pistons 8 and of duct components 9", which extends between the loading cylinders 6 which mutually connect the bores 9'.
• the duct component 9'" is a T piece, whose leg, indicated by a dash-dot line, serves to connect the duct 9 to a hydraulic fluid source.
• the ends of the duct components 9" are simply inserted in the bores, which have widened ends 9a with an abutment 9b and an O-ring 9c for sealing.
• This embodiment allows in an advantageous manner connection of the hydraulic fluid source in the duct 9 between two optional neighbouring loading cylinders 6 and also allows in an advantageous manner absorption of forces caused by heat deformation.
• the same reference numerals as in Fig. 1 are used for equivalent shoe press components.
• the securing of the pistons 8 on the beam 4 is preferably carried out in such a manner that the loading cylinders 6 can, if desired, be moved relative to the press shoe 1 in the machine direction, for moving the centre lines Cl of the loading cylinder 6 relative to the centre line C2 of the shoe press.
• Such a desideratum can be of interest for reasons described above.
• the securing device consists, in the illustrated embodiments, of a suitable number of screws 16 and screw plates 18 on opposite sides, in the machine direction, of each piston 8, and of a groove 19 formed in the piston on each said piston side.
• the hole 18' of the plates 18 lets the screws 16 through which are screwed in the beam 4, and the plates 18 engage in the grooves 19 in the sides of the pistons 8, such that when tightening the screws at the screw heads 16', the latter clamp the plates 18 between themselves and the beam 4, thereby fixedly securing the piston 8 on the beam 4.
• the plates 18 are polygonal in the same way and, as shown, eccentric.
• the centre line Cl of the loading cylinders 6 can thus be moved relative to the centre line C2 of the shoe press, if desired, by loosening the screws 16 at their heads 16' and rotating the plates around the screws 16 for permitting the desired displacement of the loading cylinder 6 in the desired direction of movement (machine direction) .
• the loading cylinder 6 in Fig. 1 is, for instance, to be moved in the direction of travel of the web W
• the right plate 18 is rotated such that an edge thereof positioned further away from the centre axis of the screw 16 engages in the right groove 19
• the left plate 18 is rotated such that an edge thereof positioned correspondingly closer to the centre axis of the screw 16 engages in the left groove 19.
• a single eccentrically flanged sectional rod or bar can be arranged on the respective sides of the loading cylinders engaging in the grooves 19 of the pistons 8 by means of a flange and screwed in the beam 4 by means of another flange, the desired movement of the loading cylinders being accomplishable by rotating, after loosening the screws, the rods about their longitudinal axis.
• a common duct 9 for feeding the work- ing chambers 10, it is achieved in an advantageous manner that the beam 4 is not weakened by a corresponding bore.
• the compartments 21 are supplied with hydraulic fluid by means of a pipe 22, whose hydraulic fluid conducting bore 22" (the hydraulic fluid source is not shown) is connected to each compartment by means of a duct 23 formed in the press shoe and a through hole 22" which can be formed in the wall of the pipe 22 and which can be formed as a throttle.
• the pipe 22 is attached to one side of the press shoe, in this case the upstream side, by means of pipe flanges 24 and screws 25.
• the pipe 22 can be common to all compartments 21 (Fig. 1) or can be separate for each compartment 21 (Fig. 2), the separate pipes 22 communicating with each other via pipe components 22a like the duct components 9", thereby making it possible to absorb heat-conditioned deformation forces applied to the pipe 22.
• the pipe 22 or the pipes 22 and the joint pipes 22a can feed hydrostatic compartments 26 between the press shoe and the opposing side of the loading cylinders 6 via ducts 27 (indicated by dashed lines) formed in the press shoe and holes formed in the pipe/ pipes, or another pipe or several other pipes with joint pipes can be arranged on the opposite longitudinal side edge of the press shoe for this purpose.
• the inventive shoe press is applicable also to calendering operations in a paper or board machine.

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• 1997
  • 1997-11-19 SE SE9704236A patent/SE510610C2/sv not_active IP Right Cessation
• 1998
  • 1998-09-30 EP EP98946771A patent/EP1027489A1/de not_active Withdrawn
  • 1998-09-30 WO PCT/SE1998/001760 patent/WO1999016969A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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