EP0630725B1 - Device for the continuous production of particle boards, fibre boards or the like - Google Patents

Description

The invention relates to a device for continuous Production of chipboard, fiberboard or Like. from a machined or frayed, with a pressure and / or thermosetting binders mixed, Starting material containing lignocellulose or cellulose with a heatable press drum and a endless, metallic over guide rollers Press belt, which the press drum on a part of its scope, forming a press section for the to be compressed, over the curing temperature of the Binder heated material, one the press belt in terms of area with a certain press pressure pressurizing device provided is, according to the earlier patent application No. 93810458.5.

Such arrangements are for example from EP 195 128, EP 324 070, DE 25 49 560 or DE 38 00 513 are known. she serve in large quantities of waste material, such as wood waste, sugarcane bagasse, cotton stalks or the like. to chipboard or fiberboard or the like. For use in the construction or furniture industry to process. This is the lignocellulosic or cellulosic starting material machined or in Fibers dissolved and in cleaned and largely dried Form with a suitable binder transferred. As particularly suitable for binding Cellulose fibers and to form solid chipboard (Medium Density Fiber Board) for example Copolymers of sodium lignosulphonate, melamine and Formaldehyde proven at a temperature of Gradually harden at around 130 ° C.

This is used to form the chipboard or fiberboard starting material mixed with binder on the Belt in the press section between the belt and the inserted synchronously with this rotating press drum, where they are under pressure and temperature is compacted and gradually hardens before being removed removed from the press drum and into the desired one Plate size is cut.

In the known arrangements, the input side, i.e. at the inlet of the starting material into the press zone Press roll provided, which is an almost line-like Press force with a press pressure of well over 100 bar on the tape. Subsequent to this on the input side press roller follows a zone in which the pressing pressure is generated only by the belt tension and then another press roller with also almost linear force. In the Usually three to four rollers are provided, whereby the last roller in the shaping of the plates produced shortly before the end of the setting process. Disadvantageous of these previously known methods is that as a result of sudden pressure stress and subsequent zones low pressure due to the multiple spring back of the Fibers insufficient strength, an undesirable Density profile and an unfavorable hardness distribution over the Thickness of the plate results and the amount of binder must be chosen unnecessarily large.

Another disadvantage is that with the known Arrangements the press drum and the pressure rollers not are sufficiently heated to provide enough heat to the Transfer material, with the result that the tape with additional heaters to the required Temperature must be brought.

A particular disadvantage is that in the known Arrangements considerable forces on the press drum bearings may occur. This requires the assignment of the individual press rolls in such a way that the bearing forces of the Press drum are at least partially compensated for by adapting to other operating conditions Balance of forces would be disturbed. Continue is disadvantageous that the press rolls the press drum like this strongly deform that no adherence to tight tolerances is possible. To the deflection with the big forces Keeping the press drum as small as possible is one considerable wall thickness of the press drum in the decimeter range required what is a weight of the press drum brings over 100 t with it. Nevertheless, this is also the case here Deflection of the press drum so large that the Thickness of the chipboard produced across the width varies inadmissibly and their shape is curved, i.e. from deviates from one level.

WO 92/19809 describes a roller with a non-rotatable one Carrier and a drum jacket rotatable around this known to have a hydrostatic inner bearing Support elements is mounted to the deflection of a Reduce press drum. The support elements are with Pressure medium supplied such that the supporting force is individually adjustable.

The invention has for its object the above mentioned disadvantages of the known arrangements avoid and in particular a facility for continuous production of chipboard, Fiberboard or the like. To create the constructive is simply constructed. With this facility, a more uniform thickness across the width of the produced Chipboard or fiberboard or a desired one Thickness profile achieved as well as a flat shape, and around a greater strength and a more homogeneous density and Hardness distribution over the thickness of the chipboard or Fiberboard will be reached, the material in the Press section in a simple way over the Curing temperature of the binder is heated, and whereby extreme bearing forces are avoided.

According to the invention, this object is achieved with the characterizing features of claim 1 solved.

The pressing device is advantageously at least on the Entry side into the press section through a pressure shoe formed with hydraulic bearing surface, which with the Press drum a gradually narrowing inlet zone and a subsequent, to a certain extent with the pressing drum area approximately uniform pressing pressure and / or distance from the press drum forms, which ensures the uniformity of the Chipboard is further improved.

In an advantageous development of the invention directly to the pressure shoe on the input side hydraulic pressure shoes are provided, which a gradually decreasing pressure on the Apply press tape. Subsequently, at the Exit side of the plates with a shaping roller the width of controllable line force can be provided to just before the end of the curing process the desired one Thickness profile or an intended surface shape to reach.

The invention is based on the in the accompanying figure illustrated embodiment of a system for Production of chipboard, fiberboard or the like described in more detail.

The system has a press drum 1 and a endless metallic press belt 2, for example a Steel strip, which covers part of the circumference of the Press drum 1 and over several deflecting rollers 3 continuously is guided so that it is over the looping part the press drum 1 with this one Press section P forms. The press drum 1 and that Press belt 2 move synchronously in the press section P. together.

A chute 4 is machined or fiberized lignocellulosic or cellulosic, with material mixed with a thermosetting binder 5 by means of a guided over pulleys 30 Conveyor belt 29 on a guide surface 28 on the Top of the horizontal press belt 2 with a certain intended basis weight heaped up and runs on the press belt 2 in the Entrance zone E of the press line P. In the press line P, the material introduced is a pressing pressure exposed and at the same time above the curing temperature of the binder heated. During the run through the press section P, the material is on the desired density is compressed and during the Lead time almost hardened. At the end F of the press section P shortly before the outlet A is formed Plate by means of a form roller 6 of a final pressure subjected and receives the desired thickness profile or the required surface quality or structure. The Endless chipboard emerging from outlet zone A. or fiberboard 7 is in a cutting device 8 cut to the desired format and deposited on a stack 9.

The press drum 1 is non-rotatable with one clamped carrier 19 rotatable drum jacket 20 provided which with at least one support device 21 is supported against the carrier 19. Because there are no journal bearings are present and the forces on the clamping of the carrier 19 are derived, this is omitted Problem of compensating the bearing forces in this Arrangement complete. The support devices 21 can in a known manner as a trailing hydrostatic, via lines 22 with pressure controllable pressure Supplied support elements are formed, which a exert adjustable supporting force on the jacket 20 and an almost frictionless bearing of the rotating Ensure drum jacket 20, or as others known support elements or as rolling elements. The Support elements 21 can be used as a continuous support bar or as arranged side by side in the axial direction, individually controllable support elements be. Also in the circumferential direction can be next to each other several support strips or rows of support elements 21 be provided. The sides of the press drum 1 are with Advantage through flexible e.g. bellows-type seals completed. Instead, it can be used as a support but also the entire one facing the press section P. Half space between carrier 19 and drum jacket 10 or a partial space can be filled with pressurized fluid. The pressure medium the support elements 21 is advantageous to one such temperature is heated so that the drum shell heated above the curing temperature of the binder and thus a sufficiently intense heating of the Material 5 in the press section P is guaranteed. In addition, the wall thickness of the Jacket 20 of the press drum 1 significantly reduced e.g. in the order of 5 cm, and that Weight of the press drum of well over 100 t to less than 50 t. In addition, the reduction the wall thickness improves the heat transport and the Reduced energy consumption. Through the targeted setting the pressure of the pressure shoes 10, 13, 14, 15 and the support elements 21 can be avoided that the drum jacket 20 under the enormous pressing forces deflects so that the thickness constancy of the Chipboard 7 significantly improved and the wear of the press belt 2 is reduced.

To form the press section P between press drum 1 and press belt 2, as well as to exercise the necessary Press pressure and for heating the press belt 2 and the material layer 5 transported thereon is on Entrance E into the press section P is a pressure shoe 10 intended. Whose surface facing the press belt 2 is shaped so that at the entrance E into the press zone P a gradually narrowing funnel-shaped Gap formed between press belt 2 and press drum 1 is, while in the subsequent press section P. almost uniform distance between press belt 2 and Press drum 1 is formed. This arises at the entrance E an initially increasing pressure, which in the subsequent press zone P almost on a certain one specified pressure value during the entire cycle time is held over the pressure shoe 10.

Compared to arrangements with an input side Press roll, which the press drum 1 essentially touched almost linearly and thus only for a short time Pressure peak at the entrance to the press nip generated, after which the pressure returned to a low Value drops and springback of the fibers enables, is in the arrangement described Pressure in the press section P over a substantial for a long time without unwanted pressure peaks and Maintain interruptions, with the result that the in this way chipboard produced a clearly better homogeneity with regard to their density and hardness distribution and show better fiber cohesion with reduced binder content and need.

The surface of the pressure shoe facing the press belt 2 10 is advantageous with one or more hydrostatic bearing pockets 11, which about Pressure lines 12 with a lubricant under certain pressure, for example sufficient temperature-resistant pressure oil are fed. This is the press belt 2 on the surface of the pressure shoe 10 hydrostatically supported and almost frictionless to slide over the pressure shoe surface. About the in the storage pockets 11 set pressure can be simultaneously the pressing pressure required in the press section P. can be set. It is also an advantage that supplied pressure oil to a temperature above the Curing temperature of the binder e.g. on over 150 ° C, so that the press belt 2 when sliding over the bearing pockets 11 and that transported material 5 above the curing temperature is held. A previous heating of the press belt 2 takes place in that the front 25 of the pressure shoe 10 has a preheating zone C, over which the belt 2 slides in front of the entry zone E, where these also with hydrostatic, over Lines 27 with hot pressurized oil bearing pockets 26 is provided.

In principle, a single one is often sufficient Pressure shoe 10. Advantageously, however, the input side Pressure shoe 10 in the press section P downstream further analog pressure shoes 13, 14 and 15 can be provided, which are against each other connect practically without interruption. The storage bags this downstream press shoes 13, 14 and 15 can with pressure oil of different pressure be fed so that a successive gradual reducing pressure, e.g. at the input pressure shoe 10 a pressing pressure of 30 - 50 bar, which in the downstream Pressure shoes gradually decrease to 2 - 3 bar. By the distribution of the press pressure over the entire press section, instead of less linear loads, is an annoying bowl-shaped deformation of the Circumferential pressing drum avoided.

The pressure shoes 10 and 13, 14, 15 can with respect the press drum 1 in a fixed position be arranged at a predetermined distance, or by means of Adjustment devices 23 against the press drum 1 to adjust the gap in the press section P in Pressing direction adjustable, e.g. manually using Spindles or automatically by means of electrical, magnetic, pneumatic or hydraulic Control. In the latter case, you can hydraulic pressure adjustable with pressure medium supplied pressure rooms can be movable, also the same pressure medium can be used as for the Supply of storage bags 11.

At the end of the press section P, a shaping roller 6 be provided which of the already largely cured Chipboard 7 by exerting a higher pressure than that of the last pressure shoe 15 definitely gives and conditions the desired shape, for example the desired thickness profile. It is an advantage this form roller with a non-rotatably clamped Carrier 16 equipped rotatable jacket 17, which with one or more support elements 18 adjustable supporting force in the pressing direction against the Support 16 is supported. The support element 18 can be a continuous support bar or it can be in the axial direction several support elements are provided side by side with which a certain thickness profile is produced can be. The support elements 18 in a manner known per se as trailing hydrostatic Support elements with individually controllable pressing force be trained or in any other known manner, or the entire press-side half space h is as through Sealing strips 24 closed pressure chamber formed. The shaping roller 6 can be adjusted in the drum circumferential direction to vary the curing distance. However, the last pressure shoe can also be used as a shaped element serve, provided that this one sufficient for shaping Exerts pressure, without a forming roller. Through the formation of the press drum and the Forming roller as a so-called deflection compensation roller can achieve a uniform and level press nip and therefore a uniform thickness and a flat shape of the chipboard produced.

Claims (8)

1. An equipment for the continuous production of chipboard, fibreboard or the like from comminuted lignocellulose- or cellulose-containing raw material (5) which is mixed with a pressure-setting and/or thermo-setting binder, the said equipment having a heatable pressure-drum (1) and an endless metallic pressure-belt (2) which is led over guiderolls and encloses the pressure-drum (1) over part of its circumference to form a pressure section (P) for the material to be compressed, which is heated above the setting temperature of the binder, at least one pressure equipment (10, 13, 14, 15) being provided, to act with a certain superficial pressure upon the pressure belt (1), characterized in that the pressure-drum (1) exhibits a non-rotating bearer (19) and a jacket (20) rotatable with respect to the latter and supported by at least one supporting element (21) with adjustable supporting force, the supporting equipment being a hydrostatic bearing zone (H) which is filled with pressure liquid and arranged at the pressure side of the pressure-drum and formed as a segment of the annular space between the inner surface of the drum (20) and the bearer (19).
2. An equipment as in Claim 1, characterized in that the pressure equipment is created at least at the side of entry into the pressure section, by a pressure-shoe (10) having a hydraulic bearing area (11) and forming with the pressure-drum (1) a gradually narrowing entry zone (E) and a succeeding region extending as the pressure section (P) over a certain arc of the pressure-drum (1) at approximately uniform pressure and/or distance from the pressure-drum.
3. An equipment as in Claim 2, characterized in that in the pressure section (P) directly adjacent to the pressure-shoe (13, 14, 15) is arranged, having a hydraulic bearing area with adjustable pressure.
4. An equipment as in one of the Claims 1 to 3, characterized in that in the pressure section (P) after the last pressure-shoe (15) a shaper-roll (16) is arranged, which exerts upon the pressure-belt (2) a higher pressure than the last pressure-shoe (15).
5. An equipment as in Claim 4, characterized in that the shaper-roll (6) exhibits a non-rotating bearer (16) and a jacket (17) rotatable with respect to the latter and supported by at least one supporting equipment (18) with adjustable supporting force.
6. An equipment as in Claim 5, characterized in that the shaper-roll (6) exhibits a number of supporting elements (18) arranged side by side in the axial direction and having individually adjustable supporting force.
7. An equipment as in Claim 5, characterized in that the shaper-roll (6) is adjustable in the direction of motion of the pressure-belt (2).
8. An equipment as in one of the Claims 1 to 4, characterized in that the shaper-roll (6) exhibits at its pressure side a part-space, especially a half-space (h) which is sealed by sealing strips (24) and may be filled with pressure fluid.

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