EP2189276A1 - Plate press and pressed sheet-pressed cushion unit - Google Patents

Abstract

The plate press (1) has a heating plate (2), a pressing plate (5) and a press pad arranged between the pressing plate and the heating plate. The press pad has a liquid cushion layer (4) at the operating temperature of the plate press, which is bounded on one side by a fluid-tight membrane (3). The membrane comprises a flexible polymer material, particularly an elastomer material such as silicone-, fluorine- or silicone-fluorine-blend elastomer or a fluorine tetra polymer. The membrane is connected with the pressing plate. An independent claim is included for a press plate-press pad unit.

Description

The invention relates to a plate press, in particular a one-floor or multi-day cycle press, with at least one hot plate, at least one press plate and at least one arranged between the press plate and the hot plate press pad having a liquid at least at the operating temperature of the plate press cushion layer on a Side is bounded by a fluid-tight membrane, which is connected to the heating plate and / or with the press plate.

Such plate presses are used in particular for coating wood-based panels with amino resins in the form of phenolic, urea, melamine, or melamine / urea mixed resins. In the pressed material or so-called compact, for example, are HDF (High Density Fibreboards), which are coated for use in the floor area (as a so-called "laminate") with melamine resins, decorative surfaces of different design can be realized. In order to achieve a high surface quality in such coating operations, a uniform pressure distribution over the entire plate press, which can have a working surface of up to 20 m ² , is of crucial importance.

Here, the functionality of the arranged between hot plate and press plate press pad is of great importance, since otherwise due to manufacturing tolerances to eventual subsequent distortion in the press and thickness tolerances in the pressed material a uniform pressure load over the entire compact would not be achieved. Press pads must therefore have sufficient elasticity, i. Compliance, possess, in order to compensate for the thickness tolerances in the pressing process. In addition, they must have a good recovery after pressure relief, as without a replacement of the press pads as large a number of press cycles should be possible. Another important feature of the press pads is their heat resistance and thermal conductivity.

The aminoplast resins mentioned above are thermosetting plastics in which the crosslinking process takes place by way of polycondensation. This means that water vapor and excess formaldehyde in vapor form are released during the pressing process becomes. The resulting vapor bubbles must during the pressing process, which runs under a pressure of about 150 N / cm ² to 600 N / cm ² and a temperature of 140 ° C to 220 ° C, in the material to be coated, ie, for example, the HDF plate , diffuse. In this context, a different pressure distribution over the press surface can lead to diffusion problems, which are manifested in errors in the surface quality of the finished product.

State of the art

While press cushions initially consisted mostly of several layers of kraft paper, today's state of the art technology is formed by a wide variety of types of textile press cushions. Due to the textile structure and the imperfectly homogeneous surface structure in principle, differences in the pressure acting effectively on the pressed material over the entire surface of the platen press can not be avoided in practice.

In addition to plate presses with textile or mat-shaped press pads and press constructions are already known in which the problem of non-uniform pressure distribution to be solved with press pads, which have a liquid cushion layer:

So is in the DE 199 37 694 A1 discloses a platen press, wherein below the press plate, a membrane is arranged in the form of a metallic plate, which is circumferentially welded to the heating plate. In a closed space between the metallic membrane plate and the heating plate, a liquid cushion layer is arranged. This padding layer consists of a lead-tin alloy, which is characterized by a good thermal conductivity. In the cold state of the press, the material of the pressure pad is cured. In order to achieve a positive connection of the metallic membrane plate with the heating plate and still allow a predetermined movement of the membrane plate relative to the heating plate, T-shaped anchoring heads are present on the underside of the membrane plate, which engage in corresponding anchoring grooves in the top of the heating plate.

A disadvantage occurs in such a press design in appearance that the production of the heating plates with the aforementioned undercut grooves is expensive, and also the membrane plate is built complicated with their anchoring heads. The change process is hampered by the positive connection between the aforementioned components.

In addition, the describes DE 10 2005 020 468 A1 a cycle press, in which also a liquid cushion layer between the press plate and the heating plate is present. In one of the in the DE 10 2005 020 486 A1 shown embodiments of a plate press adjacent to the liquid cushion layer on the one hand directly to the back of the press plate. On the other hand, the liquid cushioning layer is directly connected to the heating plate. Movable, introduced into grooves in the heating plate seals are arranged circumferentially on the edge of the heating plate, whereas the attachment of the press plate takes place on protruding edges where fasteners are located, which cooperate with frontally attached to the heating plate mounting brackets.

A disadvantage of the platen press described above is the fact that a pressure plate change can only take place after the liquid cushion layer has been more or less completely removed from the space between the press plate and the heating plate. This is done by means of a special vacuum chamber, which is connected via an emptying channel with the pressure pad chamber. The discharge operation before the removal of the press plate and the filling process, which is required after the installation of a new press plate by a separate filling channel out of a pressure chamber out again, each requires time, whereby the downtime of the press can be increased. In addition, the pressure pad space can never be completely emptied, so that inevitably certain residual amounts of the material of the liquid pressure pad still adhere to the pressure plate to be removed even after the emptying process.

From another in the DE 10 2005 020 486 A1 disclosed embodiment, it is known to form the pressure pad chamber by means of a fully enclosed enclosure. The press plate is thus on the side facing away from the pressed material with the sheath in direct contact. On the other side of the pressure pad, the wrapper rests against the heating plate. On this side, the envelope is in the area of a breakthrough with a channel located on the heating plate in connection through which the pressure pad can be filled from the outside and emptied. A disadvantage of this design is the difficulty of producing a closed, pressure-tight pressure pad from metallic material.

task

The invention has for its object to provide a platen press, which is characterized by an isobaric pressure distribution over the entire plate surface and in which the sealing of the space which is filled with the material of the liquid cushion layer, is easy to accomplish, wherein the Membrane characterized by low production costs.

solution

Based on a platen press of the type described above, the underlying object is achieved in that the membrane has a flexible polymer material, in particular an Elastomermatieral, preferably a silicone, fluorine or a silicone-fluorine blended elastomer or a fluorine-tetrapolymer.

The invention thus dispenses with the hitherto practiced alone use of metallic membranes for sealing liquid cushioning layers and is based on the approach that flexible polymer materials meet the requirements for pressing pressure and temperature as well as metallic materials, however, are cheaper to manufacture and handle. Another advantage of the flexible polymer material is that the membrane very intimately adapts to the heating plate or the press plate and thus avoids insulating air gaps, as they are not ruled out in much stiffer metallic membranes. The heat transfer from the heating plate through the press pad and subsequently the press plate onto the pressed material can therefore reach an excellent level even with the membrane according to the invention containing a flexible polymer material.

According to a preferred embodiment of the platen press according to the invention the liquid cushion layer is bounded on one of the membrane opposite side of the press plate. In this case, press plate and membrane thus form a unit which allows a quick change of press plate including press pad. In this case, the space between the press plate and the press pad can be permanently closed, so that when changing the press pad is replaced with the liquid cushion layer or there is a closable connection to the room, which before removing the press pad removal of the liquid cushion layer forming material allowed. In the latter case is too During the pressing process via the connection an influence of the pressure in the cushion layer possible. By connecting the press plate and press pad to a functional unit, the hot plate itself remain unchanged from known types of presses, so that in a simple way a change from textile press pads on a liquid cushion is possible.

An advantageous development of the press plate-press pad unit is that the membrane and the press plate in edge strips, each projecting over an outline of the heating plate, circumferentially fluid-tightly connected to each other, in particular glued or pressed. As the adhesive, it is preferable to use a condensation-crosslinked silicone adhesive which is capable of bonding the silicone elastomer-made membrane to the steel material of the press plate in a durable and temperature-resistant manner.

In order to obtain a circumferentially sufficiently large connection force between the membrane and press plate, circumferential clamping strips can be provided on the edge strips of the press plate, the edge strips of the membrane between them and the press plate clamped fluid-tight. In this case, along the edge strips circumferentially distributed arranged connecting elements, in particular in the form of screws, bolts, rivets or staples each exert a clamping force on the diaphragm, press plate and possibly intervening adhesive and / or sealant edge seal.

An alternative embodiment of the platen press according to the invention is that the liquid cushion layer is delimited on a side opposite to the membrane of the heating plate. In this case, the heating plate and membrane and the liquid cushion layer located in the intermediate space thus form a structural unit. The press plate in this embodiment may be unchanged from the prior art embodiments. This means that no special design is necessary in the frequently due to a corundum content in the surface coating of the compact sheets to be replaced, but that the press plates in the embodiment, as is common in known presses, can be maintained. As a result, the pressing process is facilitated and shortens the downtime of the press because the press plate change can be done as in known presses.

A connection of the membrane to the heating plate of the press can be carried out according to the latter embodiment, characterized in that the membrane with edge strips which protrude beyond the contour of the heating plate, connected to the hot plate, in particular glued or pressed. In this case, the edge strips can be angled relative to a plane defined by a surface of the heating plate and connected circumferentially with end faces of the heating plate.

Also in this case, it is advisable to achieve sufficiently large forces to provide terminal strips on the edge strips of the membrane over the entire circumference of the membrane or the heating plate. By means of these terminal strips edge strips of the membrane between the terminal strips and the heating plate are clamped fluid-tight, wherein if necessary, an adhesive and / or sealing means can be arranged therebetween.

In order to avoid a lateral deflection of the press pad under the pressing pressure, the terminal strips can substantially completely close a gap region between the heating plate and the press plate, as this is given in the pressing operation and thus laterally support end sides of the membrane.

In order to withstand the stresses prevailing in the press operation, the membrane should consist of a foil material with a thickness of between 0.1 mm and 10 mm, preferably between 1 mm and 3 mm. To increase the strength of the membrane may be provided with a reinforcing insert, in particular with a fabric or an alternative textile fabric of metallic and / or polymeric threads, wherein the reinforcing insert should be completely embedded in the film material to the smoothest possible surface of the membrane to reach. A smooth surface with low roughness is important in order to obtain a large contact surface to the press plate or to the heating plate, whereby the heat transfer is favored. The membrane can also be made so that the polymeric material is doctored onto the reinforcing insert, whereby the insert can be embedded more or less completely.

To further increase the heat transfer through the press pad, the film material of the membrane with heat-conducting inorganic additives, in particular with metal powder and / or quartz powder, be enriched. In such a heat conductivity-increasing substances may be, for example, alumina, boron nitride or Act of quartz flour. The proportion of additives must not exceed a certain extent, in particular approximately 40%, if possible, so that the elasticity and flexibility of the membrane is maintained.

In view of the required working temperatures of the plate presses in question, the material may be added to the liquid cushioning layer of long and / or cyclic hydrocarbons, in particular hydraulic oil, to which the thermal conductivity enhancing additives may be added, or to liquid metal or a metal alloy, in particular a lead, at the operating temperature of the platen press and / or tin and / or bismuth-containing alloy.

In order to be able to change the pressure and / or the temperature within the press pad during the pressing operation over the space filled with the liquid cushion layer, a channel for the supply and removal of the material of the liquid cushion layer may be provided, wherein the channel is the heating plate and / or penetrates the membrane and / or the press plate and is alternately closed and opened.

Finally, the object of the invention is also achieved by a press plate-press pad unit consisting of a metallic press plate and a membrane consisting of a flexible polymer material, the membrane and the press plate in respective edge strips fluid-tightly interconnected, in particular glued and / or jammed and and / or pressed, and wherein the press plate and the membrane define between them a closed space which is filled or fillable with a material which forms a liquid cushion layer at the operating temperature of a platen press. As stated above, such a press plate press pad unit can be used in existing plate presses, if the principle of textile press pad to the principle of a liquid cushion to be changed.

embodiments

The invention will be explained in more detail with reference to two embodiments of plate presses, which are shown schematically in the drawing.

Fig. 1:

Einen Querschnitt durch eine erste Ausführungsform einer Plattenpresse mit einer Pressblech-Presspolster-Einheit,

Fig. 1b:

einen vergrößerten Ausschnitt des Randverbunds der Plattenpresse gemäß Figur 1,

Fig. 2:

wie Figur 1, jedoch einer zweiten Ausführungsform mit einer mit einer Heizplatte verbundenen Membran und

Fig. 2a:

einen vergrößerten Ausschnitt der Randbefestigung der Membran gemäß Figur 2.

It shows:

Fig. 1:

1 is a cross-sectional view of a first embodiment of a platen press with a press plate press pad unit;

Fig. 1b:

an enlarged section of the edge composite of the platen press according to FIG. 1 .

Fig. 2:

as FIG. 1 but a second embodiment with a membrane connected to a heating plate and

Fig. 2a:

an enlarged section of the edge attachment of the membrane according to FIG. 2 ,

An in FIG. 1 only partially and schematically illustrated platen press 1, which is equipped in a known manner with a plurality of arranged in the press longitudinal direction press frame with upper struts and lower struts and with supported on the upper struts or Unterholmen hydraulic cylinders in addition to the components shown, moreover, a heating plate 2, a membrane 3, a cushion layer 4 made of a liquid material, a press plate 5 and a compact 6 on. In a one-day press, the structure of the same is symmetrical to a plane of symmetry 7, which is also the median plane of the compact 6. In multi-floor presses, a lower heating plate, not shown, is adjoined in turn by a third press pad followed by a second compact. The structure may continue over a plurality of floors in the same way. For the sake of simplicity, only the arrangement above the plane of symmetry 7 will be discussed in the following description.

The heating plate 2 formed as a metallic cast plate has a plurality of these passing through heating channels 8, in which circulates liquid thermal oil, which has been heated to the required operating temperature or to a certain extent beyond. An underside of the heating plate 9 is in surface, heat-conducting contact with the consisting of a silicone elastomer, flexible and a certain elasticity having membrane 3. Inside the membrane of a membrane material 3 is a complete Embedded in the silicone material reinforcing insert in the form of a fabric consisting of aramid threads.

The membrane 3, together with the press plate 5, which is made of sheet steel with a chromium layer facing the compact 6, forms a press plate press pad unit 10, which is fastened to the heating plate 2 during the pressing operation by means of fasteners not shown, but is very easily detachable therefrom without having to cancel the unit. The press pad itself consists of the above the press plate 5 arranged liquid cushion layer 4, which consists in the present case of a lead-tin alloy having a melting point of about 70 ° C to 80 ° C and the cushion layer 4 above the press plate 5 enclosing Membrane 3.

As can be seen in particular FIG. 1a results, the sealing of a space 11, in which the liquid cushion layer 4 is located in circumferentially around the heating plate 2 arranged around edge strips 12, which project beyond an outline 13 of the heating plate to the outside. In the edge strips 12 3 circumferential clamping strips 14 are also arranged above the membrane, which are braced by means of screws 15 with the press plate 5 and clamp in this way the interposed mem brane 3 and thus close the space 11 fluid-tight. The clamping strips 14 may be shaped such that they essentially close a gap region 16 extending perpendicularly to the plane of symmetry 7 between the press plate 5 and the underside 9 of the heating plate 2, so that in the operating state of the press the membrane abuts in the region of the edge strips 12 can support the sufficiently stiff terminal block 14, so that an excessive expansion of the membrane in the otherwise unprotected gap regions 16 is prevented. In FIG. 1 However, the terminal block 14 is shown as a flat rectangular cross-section which is parallel to the press plate 5, shown. In the region of the clamping strips 14 is located between the membrane 3 and the press plate 5, an adhesive layer K, which also causes a greater tightness in addition to an increased strength of the edge seal.

In the gap regions 16 of the membrane 3, a connection 17 for a line for filling the space 11 with the material of the liquid cushion layer 4 may be arranged. By means of a hydraulic pump 19, the pressure within the liquid cushioning layer 4 during the pressing operation or previously set.

An in FIG. 2 illustrated alternative plates press 1 'differs from the in FIG. 1 illustrated variant, as in the case now described, the membrane 3 'is connected to the heating plate 2', whereas there is no connection between the membrane 3 'and the press plate 5 here. This makes it possible to perform a very simple pressing plate change, and this is common in presses according to the prior art. Not shown are for reasons of clarity fasteners with which the press plate 5 is attached to the heating plate 2 '.

The membrane 3 'in the present case again consists of a silicone elastomer. Inside the silicone elastomer, which is designed as a film material, there is a reinforcing fabric made of aramid threads.

Out FIG. 2a can be seen that at end faces 20 of the heating plate 2 'circumferentially fastening strips 23 are attached. On each inner side 22 of the fastening strips 23, the membrane 3 'is supported in its edge regions. There it is circumferentially pressed by means of circumferential clamping strips 21 between the fastening strips 23 and the clamping bars 21 fluid-tight. The terminal strips 21 and the fastening strips 23 are clamped together with screws 15 which are screwed into threaded holes in the heating plate 2 '. Optionally, to improve the tightness or homogenization of the force absorption, an adhesive / sealant layer K 'between the membrane 3' and the terminal block 21 and the fastening strip 23 may be arranged. The clamping strip 21 can extend almost as far beyond the underside 9 of the heating plate 2 'that it can support the membrane with its inner side 22 almost over the entire height of the gap region 16 between the heating plate 2' and the compact 6. Due to the internal pressure in the interior 11, the medium of the liquid cushion layer 4 strives to displace the membrane 3 'in the gap region 16 to the outside. In FIG. 2 Both the terminal strips 21 and the fastening strips 23 are flush with the lower edge of the heating plate 2 '.

Within the heating plate 2 'is a channel 24, to which in turn a line 18 is connected, which leads to a hydraulic pump 19. In this way, during the pressing operation or before or after influence on the pressure within the room 4 exercise.

LIST OF REFERENCE NUMBERS

1, 1 '

platen press

2, 2 '

heating plate

3, 3 '

membrane

4

cushion layer

5

press plate

6

compact

7

plane of symmetry

8th

heating duct

9

bottom

10

Press plate-press cushion unit

11

room

12

edge strips

13

outline

14

terminal block

15

screw

16

gap region

17

connection

18

management

19

hydraulic pump

20

front

21

terminal block

22

inside

23

mounting strip

24

channel

K

adhesive layer

K '

Adhesive / sealant layer

Claims (13)

Plate press (1, 1 '), in particular a one-day or multi-day cycle press, with at least one heating plate (2, 2'), at least one press plate (5) and at least one between the press plate (5) and the heating plate (2, 2 ' ) arranged press pad, which has a at least at the operating temperature of the platen press (1, 1 ') liquid pad layer (4) which is bounded on one side by a fluid-tight membrane (3, 3') with the heating plate (2, 2 ' ) and / or with the press plate (5), characterized in that the membrane (3, 3 ') is a flexible polymer material, in particular an elastomeric material, preferably a silicone, fluorine or a silicone-fluorine blended elastomer, or a Having fluorine tetrapolymer. Plate press (1) according to claim 1, characterized in that the liquid cushion layer (4) on one of the membrane (3) opposite side of the press plate (5) is limited. Plate press (1) according to claim 1 or 2, characterized in that the membrane (3) and the press plate (5) in edge strips (12), each projecting over an outline (13) of the heating plate (2) circumferentially fluid-tightly interconnected , in particular glued or pressed, are. Plate press (1) according to claim 3, characterized by peripheral strips (14) arranged on the edge strips (12) of the pressing plate (5), which clamp edge strips (12) of the membrane (3) in a fluid-tight manner between themselves and the press plate (5) along the edge strips (12) distributed circumferentially arranged connecting elements, in particular in the form of screws (15), bolts, rivets or clamps, each exert a clamping force on the edge bond. Plate press (1 ') according to claim 1, characterized in that the liquid cushion layer (4) on one of the membrane (3') opposite side of the heating plate (2 ') is limited. Plate press (1 ') according to claim 5, characterized in that the membrane (3') with edge strips (12) projecting beyond the outline (13) of the heating plate (2 ') connected to the heating plate (2'), in particular glued or pressed, is, with the Edge strips (12) are angled relative to a through a surface of the heating plate (2 ') defined plane and circumferentially connected to end faces of the heating plate. Plate press (1 ') according to claim 5 or 6, characterized by edge strips (12) of the membrane (3') arranged clamping strips (14), the edge strips (12) of the membrane (3 ') between them and the heating plate clamped fluid-tight. Plate press (1, 1 ') according to claim 4 or 7, characterized in that the clamping strips (12) circumferentially a gap region (16) between the heating plate (2, 2') and the press plate (5), as this given in the pressing operation is substantially completely close and thus end sides of the membrane (3, 3 ') circumferentially laterally supported. Plate press according to one of claims 1 to 8, characterized in that the membrane (3, 3 ') consists of a sheet material having a thickness between 0.1 mm and 10 mm, preferably between 1 mm and 3 mm and with a reinforcing insert, in particular a fabric of metallic and / or polymeric threads is provided, wherein the reinforcing insert is completely embedded in the film material. Plate press according to claim 9, characterized in that the film material with heat-conducting, inorganic additives, in particular with metal powder and / or quartz powder is provided. Plate press according to one of claims 1 to 10, characterized in that the liquid cushion layer (4) of long-chain and / or cyclic hydrocarbons, in particular hydraulic oil, the heat conductivity increasing additives are added, or from a at the operating temperature of the platen press (1, 1 ') liquid metal or a metal alloy, in particular a lead and / or tin and / or bismuth-containing alloy exists. Platen press according to one of claims 1 to 11, characterized by a heating plate (2, 2 ') and / or the membrane (3, 3') and / or the press plate (5) penetrating and closable and openable channel (24) for the Supply and removal of the material of the liquid cushion layer (4). Press plate press pad unit (10), consisting of a metallic press plate (5) and a membrane consisting of a flexible polymer material (3), wherein the membrane (3) and the press plate (5) in respective edge strips (12) fluid-tightly interconnected , in particular glued and / or clamped and / or pressed, and wherein the press plate (5) and the membrane (3) define therebetween a closed space which is filled or filled with a material which, at least at the operating temperature of a platen press forms a liquid cushion layer (4).

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