EP0380527B1 - Process for manufacturing particle boards and similar, and suitable twin-belt presses - Google Patents

Abstract

In a twin-belt press or similar, the pressure on the mat (10) entering the machine is increased rapidly, once the latter comes in contact with the heat-transmitting surfaces (1, 2), so that the high pressure causes the outer regions of the mat to harden before the heat penetrates to the interior of the mat (10). The quality of the surface of the board (P) is thereby enhanced. For this purpose, a nip (17) for example can be provided before the run-in gap (13).

Description

The invention relates to a method of the type corresponding to the preamble of claim 1 and corresponding double belt presses.

The wood particles are flat chips, but also other particles created by chopping wood, e.g. by planing, chopping, sawing, grinding or defibrating, which are provided with a binder in the form of a thermosetting synthetic resin and are piled up or sprinkled into a mat or a fleece. The mat is pressed between the surfaces to form a plate-like or similar shaped part, the surfaces being heated and heat being transferred from the surfaces to the mat in order to raise the temperature, to bring the binder to harden and to form the mat into a compact plate or to solidify. The "surfaces" are the pressing plates or sheets in a multi-tier press and the two belts in a double belt press. Instead of flat surfaces as in the two aforementioned cases, there are also presses with a large drum and a steel band wrapped around it for the production of thin plates.

In the production of chipboard and similar materials, the pressure and temperature curve in the initial phase of the pressing is of crucial importance for the properties of the finished board. In conventional continuous presses, this compression takes place in the area of the inlet gap of the support structure, and it is already known to make the inlet gap adjustable and to control the adjustment even depending on the product (DE-PS 31 33 792, DE-AS 23 43 427), in order to be able to influence the formation of the plate properties in a suitable manner.

The plasticization, which the wood fibers or chips experience under the combined effects of pressure, heat and the carefully controlled moisture present in the mat, plays an important role in the failure of the product.

DE-OS 35 38 531, which deals with a so-called calender press of this type with a heated press drum spanned on part of its circumference by a steel belt running over guide and pressure rollers, has already described that the nonwoven preferably at the beginning of the press nip compressed to a value in the range above or below the nominal thickness of the finished plate and then enclosed between the heated press drum and the steel belt while being transported further until the particles are continuously converted into their plastic state and the binder has been brought to the required curing temperature. The measures described are intended to achieve a good board surface by means of a single pressing operation and, at the same time, due to the increased compression at the beginning of the pressing, better heat transfer in the chip layer and faster penetration the heat can be achieved in the outer areas of the compressed chip layer. Details of the pressure and temperature control are not apparent from DE-OS 35 38 531.

This also applies to the double belt press according to DE-PS 21 57 746, which is otherwise the basis of the preamble of claim 1. This double belt press has a flat part of the support structure which is adjustable by pivoting about a transverse axis and delimits the inlet section. A particularly quick and strong compression of the mat cannot be achieved here. The press has an adjustable first part of the support plate, but if the steepness of the position were sufficient to achieve the desired rapid compression, the forces that would occur would be so great that they endangered the press and would no longer transmit the necessary propulsive force from the forming belts could be, not to mention the sharp kink between the steep first part of the press plate and the press plate in the main press section, which would destroy the forming belts.

The invention has for its object to design the generic double belt press so that wood chips and similar panels of different structure can be produced on it with tolerable load.

This object is achieved by the invention reproduced in claim 1.

The tray can ensure that the mat comes into contact with the two forming tapes substantially simultaneously. The tray initially keeps the mat away from the forming belt underneath and only releases it onto the lower forming belt at a desired point in time. As a result, not only is the achievement of the desired surface improvement itself promoted because the mat is not preheated for a long time from below (as in the exemplary embodiment of DE-PS 21 57 746), but also the substantially uniform formation of the top and bottom of the plate possible.

In the double belt press according to the invention, no roll gap is provided at the inlet, but the inlet gap is delimited by the protruding support plates, the form belts conforming to the curvature of the support plates and striving apart at the inlet so that the mat only comes into contact with the form belts in the inlet is coming.

The part of the support plate adjoining the bulge of the inlet gap can be pivoted together with the bulged part in order to form a variable inlet. This is particularly important in practice because it allows different plate structures to be produced with the same machine. If the essentially flat part of the support plate is set parallel or essentially parallel to the opposite support plate, the compression takes place rapidly in the area of the bulging part and the caliber is then held, as is the case in the important application of producing thin MDF (Medium Density) Fiber Board) boards with smooth and particularly tensile surface layer is desired. These are fibreboards from 2.5 to 5 mm thick with a specific weight of 600 to 900 kg / m³, which can be used in the furniture industry without surface grinding, for example for cabinet heating and drawer bottoms, but also for painting and as a base for Laminates.

The features of the invention work together in the manufacture of MDF panels in that the mat provided with the binder is compressed very rapidly under the influence of the setting temperature which is transferred from the surfaces to the outer layers of the mat, and so quickly that when the full compression is reached, the inner zones of the mat are not yet on higher Temperatures have been warmed. The outer layers are already plasticized and compliant and cling to the surfaces with compression and formation of a smooth surface, while the inner zones are not yet plasticized and offer a correspondingly high compression resistance. With this compression, the outer layers are subject to a peak pressure that is higher than if the mat was continuously at a high temperature and then compressed to the same final thickness. The compression must therefore be reached before the inner zone of the mat warms up. The plasticization and hardening, which then initially only takes place on the outside, not only increases the smoothness, but also the hardness and tensile strength of the surface layer. As the action of pressure and heat continues, the latter also penetrates into the inner zone and there leads to plasticization of the wood particles. Since the caliber, that is to say the existence between the surfaces, is then essentially kept, there is no progressive compression on the inside, but instead hardens the mass at an essentially constant, lower density. So there is no continuously maximally compacted plate, but one with at least one side, but usually both sides, of an extremely dense, smooth and tensile surface layer, but the inside has a somewhat loose structure, so that there is a kind of sandwich effect which leads to very rigid panels that do not require any surface reworking, as is desired in the furniture industry.

If, however, the essentially flat part of the pivotable support plate is swung open so that it forms an inlet gap which narrows steadily in the running direction with the opposite support plate, then none occurs abrupt compaction with subsequently held caliber, but a gradual compaction as the warming of the inner zones of the mat progresses. In this way, a plate can be produced which is essentially constant in its properties over the thickness. Such panels are used in the furniture industry for cabinet doors or cabinet side surfaces in a thickness of the order of approximately 20 mm, and are often subjected to subsequent milling to produce folds or decorative surface reliefs. In order for the milled surface to have properties that are as constant as possible, the milling cutter must find the same material properties at all milling depths. So homogeneous properties of the chipboard are in demand here. The double belt press in question meets both of these requirements without having to make any changes other than simply adjusting the infeed area. Here, the position of the transverse axis relative to the opposite support surface can also be adjusted in order to be able to adapt the transition to the actual pressing section as required.

Embodiments of double belt presses with variable infeed are known from DE-OS 24 48 794 and DE-ASen 10 09 797 and 23 43 427, although in the latter case the support plate, in contrast to the invention, should be just elastically deformable.

Since the heat transfer from the "surfaces" to the outermost layers of the mat is a transport problem, it takes a certain amount of time. For this reason, the time from reaching the setting temperature in the outer layers to reaching the highest compression, which essentially corresponds to the final thickness of the plates, is also decisive for the invention.

It has been found that this time must be approximately 0.1 to 2 seconds (claim 2) in order to achieve the desired To achieve board structure, with thin MDF boards 0.15 to 0.5 seconds. According to the invention, the compression of the mat should be carried out in one go within the abovementioned short time to practically the final thickness of the plate.

The running distance, which corresponds to the aforementioned time and within which the highest compression must be reached, depends on the advance speed of the forming belts, which can vary considerably in individual cases, for example 30 m / min for plates of 3 mm thickness and 10 m / min for panels 16 mm thick.

The design of the protrusion in detail is a compromise between the requirements of the process and the technical possibilities of a double belt press. The process for the production of MDF boards requires a quick compression of the mat in order to achieve the preferred compression in the board surface. This is opposed to the fact that the forming tapes, which provide the advance of the mat under the pressing pressure through the pressing section, are under considerable longitudinal tensile stress, which is still superimposed on the bending stresses when the forming tapes bend. So that the yield stress range is not reached, especially at elevated temperatures, there is a lower limit of the permissible radii. A rule of thumb is that a radius of 400 mm must not be exceeded per millimeter of strip thickness. Since the form tapes used in practice have a thickness of about 1.5 to 2.0 mm, the smallest radius is in the range of 600 to 800 mm, from which the diameter of the deflection drums of about 1500 mm which is usually used is derived from that of smallest occurring radius of the bulge should be substantially the same (claim 3).

The inlet gap does not have to have a purely circular longitudinal section, but can also be one of the Circular shape have slightly different, steady shape. The only important thing is that the permissible smallest radius is not fallen below at any point and the desired rapid compression is nevertheless achieved at a given working speed.

It may be advisable to heat the forming tapes before they run in between the support plates (claim 4).

However, if the form tapes can be heated sufficiently high by the deflecting drums, a heat shield may also be necessary, for example in the area before the inlet where the hot form tape faces the unprotected surface of the mat and the precautions could be taken to prematurely start the hardening without precautions (claim 5).

If the plates are to be symmetrical in their construction, one can proceed according to claim 6.

So that the contact points of the mat on the lower or upper forming belt can be adjusted in their position, an adjustability of the front edge of the tray according to claim 7 is recommended, which can be realized structurally in the manner specified in claims 8 and 9.

• Fig. 1 zeigt einen vertikalen Teillängsschnitt durch den Einlaufbereich einer erfindungsgemäßen Doppelbandpresse;
• Fig. 2 zeigt eine vergrößerte Darstellung des in Fig. 1 strichpunktierten Bereichs;
• Fig. 3 und 4 zeigen Ausschnitte der Kompressionszone aus Fig. 1 in vergrößertem Maßstab;
• Fig. 5 und 6 zeigen Teillängsschntite durch die zwischen den Formbändern eingesperrte Matte bzw. fertige Plattenbahn;
• Fig. 7 zeigt eine Seitenansicht der Presse, Fig. 7a und 7b den Kaliberverlauf bei unterschiedlichen Einstellungen der Presse.

In the drawing, an embodiment of the invention is shown schematically.

• Fig. 1 shows a vertical partial longitudinal section through the inlet area of a double belt press according to the invention;
• FIG. 2 shows an enlarged illustration of the region shown in broken lines in FIG. 1;
• 3 and 4 show sections of the compression zone from FIG. 1 on an enlarged scale;
• 5 and 6 show partial longitudinal sections through the mat or finished sheet web locked between the forming belts;
• Fig. 7 shows a side view of the press, Fig. 7a and 7b the caliber course with different settings of the press.

The double belt press designated as a whole in FIG. 1 with 400 comprises a lower forming belt 1 and an upper forming belt 2 made of sheet steel of approximately 1.5 mm thickness, which endlessly rotate one above the other in a vertical plane. The shaping belts 1, 2 are deflected via deflecting drums 3, 4 which correspond to two further deflecting drums (not shown) on the right outside of FIG. 1 and whose bearing points are displaceable for the purpose of tensioning the shaping strips. The upper run of the lower forming belt 1 and the lower run of the upper forming belt 2 lie one above the other at a short distance and form pressing surfaces between which the mat 10 is pressed together according to a certain time program. The forming belts 1, 2 run in a horizontal, essentially flat pressing section 38, 5 at the same speed in the same direction indicated by the arrow 18. In the pressing section 38.5, a mat 10 of wood chips provided with binding agent, which is located between the shaping belts 1, 2, is exposed to the action of pressure and heat and cured to form a coherent plate web P (FIG. 6). The form belts 1, 2 are driven via the deflection drums. The deflection drums 3, 4 shown are heated and have a heat-conducting surface, so that the heat is transferred to the forming strips 1, 2. The heating is dimensioned in such a way that the shaping tapes 1, 2 reach a temperature during one revolution around the deflecting rollers 3, 4, which is sufficient to harden the layers 10 of the mat 10 locked between the shaping tapes 1, 2 adjacent to the shaping tapes 1,2.

A lower support plate 6 is arranged in the pressing section 38, 5 below the upper run of the forming belt 1 and an upper support plate 7 above the lower run of the upper forming belt 2. In the longitudinal channels of the support plates 6.7 run endless roller chains, not shown, which support the dreams of the conveyor belts 1, 2 in the pressing section. The support plates 6, 7, in turn, are supported on support structures designated as a whole by 8 or 9, which consist of I-beams 11, which successively follow one another in the running direction and extend across the width of the shaping strips 1, 2, one of which is above and one above the other is vertically opposite below the pressing section 38.5 and is laterally connected to the outside of the forming belts 1, 2. The pressure is applied by hydraulic pressure elements 12 arranged between the support structure 8 and the lower support plate 6, by means of which the caliber, ie the distance between the mutually facing strands of the shaping belts 1, 2 in the pressing section 38, 5, can also be controlled. The press section 5 can be 10 to 20 m long; 1, a whole number of carrier pairs 11, 11 follow to the right. At the left end according to FIG. 1, the support plates 6, 7 form an inlet gap 13 which narrows in the running direction of the forming bands 1, 2. The deflection drums 3, 4 have moved as close as possible to the inlet gap 3.

The mat 10 is not deposited by the spreading device, as usual, on the upper run of the lower forming belt 1, which would then be brought out much further to the left. Rather, the formation of the mat takes place in another way, and the mat 10 is brought up via a tray 30 which extends in the running direction 18 into the inlet gap 13. The mat 10 slides from the tray 30 over its front edge 31 onto the lower forming belt 1 and is then carried along on it.

The actual pressing section 5, in which the forming belts 1, 2 run essentially parallel, is preceded by an inlet section 37, which is considerably shorter than the pressing section 5 and, in the exemplary embodiment shown, a part 38 with flat support plates 6, 7 extends over a length of six pairs of beams 11, 11, and includes an upstream inlet section 50 which extends only over the length of a pair of beams 11˝, 11˝ and in which the support plates 6, 7 are bent apart so that the outermost, ie 1 and 2 left ends of the convex against the incoming into the inlet gap 13 mat 10 bulging parts 6 ', 7' with the plane of the mat 5 include angles of about 40 °. In the exemplary embodiment shown, the curved parts 6 ', 7' are evenly bulged against the mat 10, ie they form partial cylinder surfaces with a radius which corresponds approximately to the radius of the deflection drums 3 and 4, respectively. The support plates 6.6 'and 7.7' are in one piece or in any case connected to one another to form a rigid unit. The form belts 1.2 do not run approximately parallel, but obliquely from above and below into the inlet gap 13 and nestle from the ends of the bulging parts 6 ', 7' of the support plates 6.7 to them, so that they are from the beginning are in thermal contact with the heated support plates 6,6 'and 7,7' and are already at the required temperature when they come into contact with the mat 10, as is the case at points 34, 35. (Fig. 2)

In order to additionally heat the shaping tapes 1, 2 before they come into contact with the mat 10, additional heating elements 39 are provided, which are indicated by dashed lines in FIG. 1. The deflection drums 3, 4 can also be heated. If the deflection drum 4 takes over the sole heating of the forming belt 2 and the forming belt 2 is heated up correspondingly high, a heat shield 41 can be attached over the incoming area of the mat 10, so that the mat 10 does not prematurely open on its upper side due to the radiant heat of the forming belt 2 Temperatures are brought at which the curing begins. At point 43, the inlet section 50 merges continuously into section 38, in which the support plates 6, 7 are essentially flat.

The transfer and feed zone is drawn out again enlarged in FIG. 3. The front edge 31 of the tray 30 is formed by a cutting-like pivoting member 33 which can be pivoted about a transverse axis 32 at its end remote from the front edge forming the cutting edge. 3, the underside of the mat comes into contact with the hot lower shaping belt 1 at approximately the point 34, while the top of the mat 10 comes into contact with the upper shaping belt resting against the upper support plate 7 at approximately 35 2 starts. The locations 34 and 35 are therefore the locations at which the outermost layers of the mat 10 experience the setting temperature.

In the exemplary embodiment shown, the locations 34, 35 are not at the same height. By pivoting the pivot member 33 in the position shown in dashed lines down, the mat 10 lowers earlier, so that the point 34 moves to the left and the point 35 to the right and thus the position of the contact points can be changed. If the plate to be produced from the mat 10 is to be made the same on both sides, care will be taken to ensure that the locations 34, 35 are approximately at the same height, viewed in the direction of travel of the mat 10.

In Fig. 4, a tray 30 'is indicated, the front edge 31 can be adjusted by shifting in the direction of the arrow. In the exemplary embodiment shown, the points 34, 35 of the contact of the mat 10 with the hot forming tapes 1, 2 are approximately at the same height.

It is essential in the production of MDF boards that the maximum compression in the apex 43 is reached from the locations 34, 35 in a short time of 0.1 to 2 seconds.

In a specific exemplary embodiment, the diameter of the deflection drum 4 is approximately 150 cm and the distance shown in FIG. 3 from the area of the contact points 34, 35 to the apex of the roll gap is approximately 25 cm. At a working speed of the double belt press 100 of 15 m / min, 1.0 seconds are required to pass the distance 36.

It is understood that in the case of points 34, 35 which are not at the same height, the point furthest from the apex 43 of the inlet gap 13 (35 in FIG. 3) must satisfy the condition that the running time should be 0.1 to 2 seconds. If the running time in contact with the hot forming tapes becomes too long, the mat is thoroughly heated and the effect illustrated in FIG. 5 cannot be achieved.

Fig. 5 indicates the situation in the inlet gap 13. The mat 10 has only been in contact for a short time of 0.1 to 2 seconds with the strands 1 ', 2' of the shaping belts 1, 2 and experiences a strong compression in the inlet gap 13 , while the heat from the strands 1 ', 2' transferred only into the outermost layers 10 'and the middle zone 10' of the mat 10 is still cold. So you oppose the compression a much greater resistance than the chips in the outer layers 10 ', which are already plastic and are highly compressed, which is characterized by the greater density of the lines indicating the chips in the zones 10'. At the same time, however, due to the increased temperature present in the zones 10 ', the binder sets, which is represented by the cross hatching.

In this state, ie with compressed and tied outermost layers 10 'and not tied inner zone 10 ", the mat 10 runs between the runs 1' and 2 'in the inlet gap 13 and the pressing section 5, where they act over a longer period of time of pressure and heat is exposed, which leads to the fact that the heat penetrates into the inner zone 10 ″ and the hardening also takes place there, which is to be indicated schematically by the somewhat coarser cross hatching in FIG. 6.

Although preferred, it is not necessary that the surface quality improvement be sought on both sides of the plate P. If, for example, primarily the upper side of the mat 10 according to FIG. 1 is to be compressed, the lower deflection drum 3 need not be heated.

As indicated by dash-dotted lines in Fig. 1, the lower support plate 6,6 'is as a rigid unit by a right according to Fig. 1, i.e. the pressing section 5 facing the end of section 38 located transverse axis 42 downward by a few degrees from the upper support plate 7,7 '. This is done by corresponding actuation of the pressure elements 12. It is not absolutely necessary for the transverse axis 42 to be formed by a transverse pin attached to the support plate 6, 6 '. It can be an imaginary axis. The inclination of the support plate 6,6 'results from the setting of the pressure elements 12. This also makes it possible to shift the transverse axis 42 from the upper support plate 7,7' away according to FIG. 1 somewhat further downward, so that a results not only in the angle, but also in the clear width variable inlet area 37. It is understood that instead of the lower support plate 6,6 ', the upper support plate 7,7' could be pivoted and that both support plates 6,6 'and 7,7' can be pivoted.

The importance of this construction is explained again with reference to FIGS. 7, 7a and 7b. The overall view of FIG. 7 reveals the convexly curved inlet section 50, the subsequent flat section 38 and the actual pressing section 5, which is also essentially flat.

7a and 7b the course of the support surfaces through the entire double belt press 400 is indicated.

400 thin MDF boards with a thickness of 2.5 to 5 mm and a specific weight of 600 to 900 kg / m³ are to be produced on the double belt press, as are used for rear walls of cupboards and for drawer bottoms and which have a particularly solid and smooth top layer should have, the support plate 6,6 'according to FIG. 7a is set so that it is parallel in section 38 of the support plate 7. The rapid compression has ended at the end of the inlet section approximately at point 43, at which inlet section 50 merges into section 38. From then on, the caliber is essentially maintained, i.e. the support surfaces S₁, S₂ are parallel to each other at a distance which corresponds to the final thickness. The embodiment shown in FIG. 7a is concerned with the production of a thin plate 2.5 mm thick. The caliber "2.5" is held from point 43 to the end of the pressing section 5, as indicated by the corresponding numbers in Fig. 7a.

However, if, as in the exemplary embodiment in FIG. 7b, a plate with a thickness of 20 mm is to be produced, in which a structure that is as homogeneous as possible is present over the thickness, then the lower support plate 6 is swung open somewhat and removed from the support plate 7, 7 'in total so that there is a course in which at the beginning of the support plate 7 a mutual distance of the support gaps 6,7 of 90 mm, at the end of the support plate 7 a mutual distance of the support plates 6,7 of 25 mm. By appropriate actuation of the pressure elements in the pressing section 5, a wedge-shaped course is also brought about up to approximately the position 44 in the first half of the same, the initial width with the width matches at the end of the support plate 7. From the point 44 to the end of the pressing section 5 on the right-hand side according to the drawing, the distance between the supporting surfaces S 1, S 2 remains constant.

With this setting of the machine, the compression does not end right at the beginning, as is the case at point 43 in the setting according to FIG. 7a, but takes place more slowly up to point 44 inside the pressing section 5. As a result, the wood particles are warmed into the interior of the mat and there is a more even compaction and hardening over the plate thickness without density and tensile strength peaks on the surface.

Claims (9)

1. A twin-belt press for the continuous production of chipboards and similar board materials consisting of wood particles held together by a binder which sets under pressure and heat,
   comprising two metal forming belts which revolve endlessly over reversing drums, advance at the same speed one above the other in a flat pressing zone, and bear against a support structure, the mat formed from the particles entering between said forming belts at a heated entry portion of the support structure which narrows at right angles to the mat plane in the direction of mat movement, the mat being compressible between said forming belts under the action of pressure and heat in the substantially flat pressing zone,
   comprising a feed means through the agency of which the mat is formed and is adapted to be fed to the entry gap between the forming belts,
   characterised in that the feed means comprises a tray (30̸) which is provided above and close to the top run (1′) of the bottom forming belt (1) and extends to close to the top reversing drum (4), over which tray the mat (10̸) is introduced between the forming belts (1, 2),
   in that at least one of the support plates (6, 7) of the support structure (8, 9) which define the entry gap (13) and which support the forming belt there with the transmission of pressure and heat, has a convex anterior curvature towards the mat (10̸) in the vertical longitudinal plane of the twin-belt press (40̸0̸),
   in that the forming belt there adapts to the anterior curvature, the anterior curvature and the heat transmission being so designed that the distance (36) between the point (34, 35) of first contact between the forming belt (1, 2) and the mat (10̸), and the transition (43) to the adjoining flat portion of the support plates, is traversed in a period of time in which the heat transmitted by the forming belt (1, 2) has not yet reached the inner zone (10̸˝) of the mat (10̸),
   in that adjoining the entry portion (50̸) of the support plates having the anterior curvature there is disposed, in the direction of movement of the mat (10̸), a substantially flat portion (38) of the support plates which, together with the entry portion (50̸) having the anterior curvature, forms a separate rigid unit which precedes the pressing zone (5) and which is pivotable about a transverse axis (42) situated in the zone of the support plate at the end situated in the direction of movement of the mat (10̸),
   and in that the vertical distance between the transverse axis (42) and the opposite support plate (7), is adjustable.

2. A twin-belt press according to claim 1, characterised in that the time is from 0̸.1 to 2 seconds.

3. A twin-belt press according to claim 1 or 2, characterised in that the smallest radius of the anterior curvature is substantially equal to the radius of the associated reversing drums (3, 4).

4. A twin-belt press according to any one of claims 1 to 3, characterised in that a heating element (39) is associated with at least one forming belt (1, 2) whereby the latter is heatable directly before the entry into the entry portion (50̸).

5. A twin-belt press according to any one of claims 1 to 4, characterised in that a heat shield (41) is associated with a forming belt (2) immediately opposite the mat (10̸) and keeps heat radiation from the forming belt (2) away from the mat (10̸) before the contact of the latter with the forming belt (2).

6. A twin-belt press according to any one of claims 1 to 5, characterised in that the mat (10̸) is so guided by means of the tray (30̸) as to come into contact with both forming belts (1, 2) simultaneously.

7. A twin-belt press according to any one of claims 1 to 6, characterised in that the front edge (31) of the tray (30̸, 30̸′) facing the top reversing drum (4) is adjustable in respect of its position.

8. A twin-belt press according to claim 7, characterised in that the front edge (31) is pivotable up and down about a transverse axis (32).

9. A twin-belt press according to claim 7, characterised in that the front edge (31) is adapted to be advanced and withdrawn parallel to the direction of movement of the forming belts (1, 2).

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