SHOE PRESS FOR PAPER OR BOARD MACHINES

Abstract: A shoe press for paper or board machines comprises a press shoe (200); a counter roll (312); the press shoe and the counter roll forming between themselves an extended nip (N) for a paper or cardboard web (W) and a circulated flexible belt (311); and hydraulic loading cylinders (210) for pressing the press shoe against the counter roll. First and/or second hydrostatic compartments (101; 201) are arranged in the side of the press shoe facing the counter roll and between the opposite side of the press shoe and the loading cylinders, respectively, and are adapted to be supplied with hydraulic fluid. At least one pipe (103; 203) for said hydraulic fluid supply is releasably attached to one side (104) of the press shoe in the longitudinal direction thereof, and said pipe has through holes (108; 208) in its wall, which holes each communicate with a duct (102; 202) at one end thereof, the ducts being formed in the press shoe. Said ducts open at their other end into a working chamber (201) in the loading cylinder and/or into said first hydrostatic compartment and/or into said second hydrostatic compartment.

Description: SHOE PRESS FOR PAPER OR BOARD MACHINES The present invention relates to a shoe press for paper/board machines. Shoe presses generally comprise a press shoe and a counter roll, which components form an extended nip between themselves for treating, e.g. dewatering in the press section of the paper machine, a paper or cardboard web, which together with a circulated flexible belt, in the press section of the paper machine in most cases referred to as press belt, runs through the extended nip. Shoe presses generally also comprise pressure-actuatable piston-and-cylinder units which are distributed along the press shoe (in one or more rows in the longitudinal direction of the press shoe) and adapted to press the press shoe against the counter roll (below referred to as load- ing cylinders), see e.g. EP 345 501 B2 ; DE-195 15 832 Cl and DE-44 09 316 Cl. Sometimes shoe presses also comprise compartments arranged in the press shoe surface facing the counter roll and, in operation, containing fluid under hydro- static pressure for lubricating the belt, see e.g. EP-345 501 B2. Moreover shoe presses may comprise a compartment or pressure chamber between each loading cylinder and the press shoe, which may be open towards the press shoe and in operation contains fluid under hydrostatic pressure. The pressure chamber acts to transmit the pressure of the loading cylinder to the press shoe for pressurising thereof and to form a hydraulic fluid pad, see e.g. DE-195 15 832 Cl. The above-mentioned loading cylinders, compartments/ chambers thus require access to hydraulic fluid. The compartment for hydrostatic pressure according to EP-345 501 B2 is pressurised by hydraulic fluid through a duct which is common to all the pockets and is horizon- tally bored in the frame system of the shoe press in the longitudinal direction of the shoe press, and bored ducts with a throttle between these and each compartment. The throttle serves the purpose of making the pressure condi- tion of each compartment essentially independent of the pressure conditions of the other compartments. According to EP-345 501 B2, also the loading cylinders are pressurised by hydraulic fluid via ducts bored in the frame system of the shoe press. According to DE-195 15 832 Cl, use is also made of ducts bored in the frame system of the shoe press and intended for pressurising the loading cylinders by hydraulic fluid as well as for pressurising the pressure chamber between the press shoe and the loading cylinder by hydraulic fluid, via a throttle. Boring the frame system, in most cases consisting of steel beams, in a shoe press for pressurising by hydraulic fluid is a complicateα and expensive procedure. The ducts formed are also invariable. There is a need of simplifying and making the supply of hydraulic fluid to the compartments/chambers and the loading cylinders less expensive. This need is satisfied by the invention, according to which hydraulic fluid is supplied to the loading cylinders, the compartments/chambers via prefabricated pipes which are releasably attached to the press shoe, in the longitudinal direction thereof (cross-direction of the paper machine) . More specifically, the shoe press according to the invention has the characteristic features of claim 1 and the advantageous features of the dependent claims: Among essential advantages of the invention, the following should be mentioned: - Low cost: pipes can be made in a less expensive fashion than precision-bored ducts in frame parts. - It is easy and inexpensive to modify a shoe press provided with such a pipe/such pipes: for instance for changing the diameter/throttle dimension. - The pipe material is optional. Various requirements may be taken into consideration, e.g. thermal expansion, duct machining accuracy. In many cases the press shoe is made of aluminium. Also the pipe can be made of aluminium and be manufactured in a simple manner by extrusion, in which case the pipe can be manufactured with fixing means or be profiled in some other manner. Embodiments of the invention will now be described in more detail with reference to the accompanying draw- ings, in which Fig. 1 illustrates the inventive idea applied to a hydrostatic compartment between a press shoe and a circulated flexible belt; to a loading cylinder; and to a hydrostatic compartment or pressure chamber between the loading cylinder and the shoe press frame, Fig. 2 illustrates the inventive idea applied to a pressure chamber between the press shoe and the loading cylinder, Fig. 3 illustrates the inventive idea applied to a pressure chamber between the loading cylinder and the press shoe; and to a hydrostatic compartment between the press shoe and the circulated flexible belt, and Fig. 4 illustrates the inventive idea applied to a hydrostatic compartment between the press shoe and the circulated flexible belt (press belt) ; to a pressure chamber between the loading cylinder and the press shoe; and to a loading cylinder. All Figures are cross-sectional views of the shoe press parts which are essential to the understanding of the invention, it being understood that the press -shoe is a single piece extending in the cross direction, whereas the loading cylinders, compartments, pressure chambers are preferably several, distributed in the longitudinal direction of the press shoe. Reference is first made to Fig. 1. The hydrostatic compartments 101 which are per se known and arranged in a row in the upper side of the press shoe 200 are each by means of a duct 102 bored in the press shoe 200 connected to a sectional pipe 103 which is releasably attached to one longitudinal side edge 104 (in this case, the inlet side) of the press shoe by means of screws 105 which engage in threaded holes 105' in the press shoe. The duct of the sectional pipe 103 which is intended for hydraulic fluid supply, is designated 106, and the attachment of the sectional pipe to the press shoe is carried out by means of sectional pipe flanges 107. The duct 106 is con- nected to the ducts 102 by means of a throttle 108 each, which is formed of a hole in the wall of the sectional pipe 103. The screws 105 thus permit removal of the sectional pipe 103 from the press shoe 200, and mounting of a dif- ferent sectional pipe 103 on the press shoe 200, having a different throttle 108/diameter or made of a different material, thus is possible. According to Fig. 1, the working chamber 201 of the loading cylinders 210 is also supplied with hydraulic fluid from a sectional pipe 203 containing a duct 206, which is connected with ducts 202, which are bored in the press shoe 200 and which extend to their working chambers 201. The sectional pipe 203 is releasably attached to one longitudinal side edge 204 (in this case, the outlet side) of the press shoe 200 by means of screws 205. The wall of the sectional pipe 203 has a bored hole (throttle) 208 for each duct 202. Also in this case, the screws 205 are screwed into sectional pipe flanges 207 and mating threaded holes 205' in the press shoe. The counter roll, the paper/cardboard web and the circulated belt are designated 312, and 311, respectively, and the shoe press frame is designated 309. N designates the extended nip of the shoe press, and F designates a press felt, which is present if the shoe press is to be inserted in the press section of the paper machine. According to the embodiment in Fig. 1, there is also a hydrostatic compartment or pressure chamber 211 between the frame 309 and the loading cylinder 210, more specifically between the piston 210A of the loading cylinder and the frame. This pressure chamber 211 communicates with the working chamber 201 via a duct 212 with a throttle 213. Thus, the duct 206 supplies also the pressure chamber 211 with hydraulic fluid. A sealing O-ring between the piston 210A and the cylinder of the loading cylinder, formed of a recess 210B in the underside of the press shoe, is designated 214. Fig. 2 illustrates the inventive principle applied to the supplying of hydraulic fluid to a pressure chamber 301 between a loading cylinder 310 and the press shoe 300. A throttle from the hydraulic fluid conducting duct 306 in the sectional pipe 303, attached to one longitudinal side edge 304 of the press shoe, is designated 308, and a duct 302 with the duct parts 302' and 302" bored in the press shoe 300 connects the duct 306 and the hydrau- lie fluid chamber 301 with each other via the throttle 308. The releasable connection between the sectional pipe 303 and the press shoe 300 is illustrated by the screw/ screw hole joints 305, 305'. Moreover, reference numerals 325; 326; 327; 330; 340; 340'; 350; 309 and 380 relate to the working chamber of the loading cylinder 310; the hydraulic fluid supply of this chamber (a common horizontal duct 326 and separate vertical ducts 327); the piston in the loading cylinder 310; the cylinder part in the loading cylinder 310; an annular boundary surface on the cylinder part 340 for the pressure chamber 301; screws for attaching the piston to a horizontal supporting beam associated with the frame system of the shoe press and an O-ring seal between the cylinder part 340 and the piston 330 of the loading cylinder. Reference numeral 336 designates a gap between the side of the press shoe 300 facing the cylinder part 340 of the loading cylinder 310 and the opposing side of the cylinder part 340, to which gap, in operation of the press shoe, hydraulic fluid can be supplied via the duct 302, the sectional pipe 303 and the hydrostatic compart- ment 301, such that the press shoe 300 is floatingly suspended, which prevents jamming. This is illustrated by arrows . In Fig. 3, one and same sectional pipe 403 which like in the embodiments above is attached to one longitu- dinal side edge 404 (in this case, the inlet side) of the press shoe 400 by means of screws/screw hole joints 405, 405', supplies hydraulic fluid both to hydrostatic compartments 401 between a circulated flexible belt (press belt) and a press shoe 400, and to pressure chambers 301 between loading cylinders 410 and a press shoe 400. In addition to the throttles 408 in the wall of the pipe 403, which are mainly intended for the hydrostatic compartment 401, there is formed in the part 402" of the ducts 402 bored in the press shoe 400 a throttle 402A opening into the pressure chamber 301, and the ducts 402 in the press shoe have a branch 402' to the hydrostatic compartment 401. The supply of hydraulic fluid to the working chamber 425 of the loading cylinders 410 is carried out by means of a horizontal duct 426 (which is com- mon to all loading cylinders) formed in the piston 410B of the these cylinders, and a vertical duct 427 extending from the horizontal duct 426. The cylinder part of the loading cylinders is designated 410A. The piston is attached to the supporting beam by means of screws 450. An O-seal between the cylinder 410A and the piston 410B is designated 480. An O-seal for the pressure chamber 301 is designated 430. While in the examples according Figs 1-3 above, sectional pipes for supplying hydraulic fluid are releasably attached to one or both longitudinal side edges of the press shoe, a sectional pipe 503 for supplying hydraulic fluid is, in the embodiment of the invention according to Fig. 4, releasably attached in a recess 520 in the side of the press shoe 500 facing the loading cylinder. The sectional pipe 503 contains two ducts or bores 506, 506', the duct 506 extending, via a throttle 508 in the sec- tional pipe 503 and a duct 502 in the press shoe 500, to a hydrostatic compartment 501 in the side of the press shoe facing the counter roll 312, while the other duct 506' extends to a pressure chamber 511 between the press shoe 500 and the loading cylinder 510, via a throttle 508'. The pressure chamber 511 communicates with the working chamber 521 of the loading cylinder 510 via an opening 512 in a sleeve 510C connected to the cylinder part 510A (in which the piston 510B of the loading cylinder is received) of the loading cylinder 510, a screw 513 being fixed in the piston 510B. The screw has a head 514 which throttles the opening 512 when the loading cylinder has reached its maximum stroke. Also in this case, the sectional pipe 503 has flanges 507, by means of which it is releasably screwed (screw 505, screw hole 505') into the press shoe 500. The supply of hydraulic fluid to the sectional pipe/ pipes 103, 203, 403, 503 can be effected via one end or both ends thereof. The sectional pipes 103, 203, 403, 503 are preferably made of the same material as the press shoe, preferably aluminium (alloy) , the sectional pipes advantageously being extruded. A hydraulic fluid feed pipe to the sectional pipe 403 in Fig. 3 is designated 411. It will be appreciated that the sectional pipes need not be fixed to the press shoe by means of screw joints, as described above. The fixing methods/means may vary within the scope of the invention; for instance, flanges in the sectional pipe may engage in grooves formed in the press shoe. A different fixing arrangement consists of screws which together with a washer are screwed into the press shoe outside the pipe flanges, e.g. 207, such that the screw head clamps, via the washer, the pipe flanges against the press shoe. The arrangement is advantageous since it allows a certain relative motion of pipe and press shoe, which may be necessary if, for instance, the pipe is selected to be made of a material other than that of the press shoe (temperature aspects) . It will also be appreciated that the straight sectional pipes described above are common to all hydrostatic compartments/pressure chambers and loading cylinders, if more than one, i.e. the sectional pipes supply the compartments/pressure chambers/loading cylinders with hydraulic fluid via a bore/throttle/duct each. The inventive shoe press is applicable also to calendering operations in a paper or board machine.

Claims: CLAIMS 1. A shoe press for paper or board machines, com- prising - a press shoe (200; 300; 400; 500), - a counter roll (312), - the press shoe and the counter roll forming between themselves an extended nip (N) for a paper or cardboard web (W) and a circulated flexible belt (311) , - at least one hydraulic loading cylinder (210; 310; 410; 510) for pressing the press shoe against the counter roll, - first and/or second hydrostatic compartments (101; 201; 301; 401; 211; 501; 511) arranged in the side of the press shoe facing the counter roll and between the opposite side of the press shoe and the loading cylinders, respectively, and adapted to be supplied with hydraulic fluid, c h a r a c t e r i s e d in that - at least one pipe (103; 203; 303; 403; 503) for said hydraulic fluid supply is releasably attached to one side (104; 204; 304; 404) of the press shoe in the longitudinal direction thereof, - said pipe having through holes (108; 208; 308; 408; 508; 508') in its wall, - ducts (102; 202; 302; 402; 402'; 402"; 502) each communicating with a hole at their one end are formed in the press shoe, - said ducts at their other end each opening into a working chamber (201; 521) in the loading cylinder and/or into said first hydrostatic compartment and/or into said second hydrostatic compartment. 2. A shoe press as claimed in claim 1, c h a r a c t e r i s e d in that the pipe is releasably attach- ed to the shoe on one longitudinal side edge of the press shoe . 3. A shoe press as claimed in claim 1, c h a r a c t e r i s e d in that the pipe is releasably attached to the press shoe integrated into the press shoe side facing the loading cylinder. 4. A shoe press as claimed in any one of claims 1-3, c h a r a c t e r i s e d in that the holes of the pipe are in the form of throttles. 5. A shoe press as claimed in any one of claims 1-4, c h a r a c t e r i s e d in that the duct in the press shoe connects said holes of the pipe at least with a hydrostatic compartment in the side of the press shoe facing the counter roll. 6. A shoe press as claimed in any one of claims 1-5, c h a r a c t e r i s e d in that the duct in the press shoe connects said holes of the pipe at least with a hydrostatic pocket between the loading cylinders and the press shoe. 7. A shoe press as claimed in any one of claims 1-6, c h a r a c t e r i s e d in that the duct in the press shoe connects the holes of the pipe at least with the working chambers of the loading cylinders. 8. A shoe press as claimed in any one of claims 1-7, c h a r a c t e r i s e d in that the sectional pipe (503) has two ducts or bores (506; 506'), one communicating with hydrostatic compartments in the side of the press shoe facing the counter roll and the other communicating with hydrostatic compartments between loading cylinders and the press shoe, the pipe being integrated into the underside of the press shoe. 9. A shoe press as claimed in any one of claims 1-8, c h a r a c t e r i s e d in that the pipe is made of the same material as the press shoe, preferably aluminium (alloy) . 10. A shoe press as claimed in any one of claims 1-9, c h a r a c t e r i s e d in that the pipe has flanges for attaching the pipe to the press shoe by means of screws and threaded screw holes in the press shoe. 11. A shoe press as claimed in any one of claims 1-9, c h a r a c t e r i s e d in that the pipe has flanges for attaching the pipe to the press shoe by means of screws and washers, the screw holes in the press shoe being located outside the flanges, and the screw heads clamping, via the washers, the flanges against the press shoe .

Inventors: BROX ERIK, BROX, ERIK
Applicants: VALMET KARLSTAD AB, VALMET-KARLSTAD AB
Application year: 1998
Main classification: D21F3
IPC codes: D21F3