RU2574175C2 - Press-pad for hydraulic pad - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of multiply and flexible printed boards and coated wood materials. Claimed press-pad comprises interconnected the first and second plies impermeable for fluids. The first ply comprises elastomer and fibres bonded therewith and has channels made at the side facing the second ply. Said channels accommodate the fluid material kept at least at the press operating temperature. The channels are closed by at least the second ply to make them impermeable for fluids.

EFFECT: adjustable elasticity of press-pad.

16 cl, 6 dwg

Description

The invention relates to a press pad for a hydraulic press comprising a first fluid impermeable layer that contains an elastomeric material and fibers connected thereto, and a second layer connected to the first layer, which is also impervious to fluids.

Such a press pad is known from EP 0235582 A2. The already known press pad should serve, in particular, in the manufacture of multilayer and flexible printed circuit boards for printed electronic circuits in the so-called high-pressure presses. Press pads for the production of materials for electronic printed circuit boards are manufactured using high pressures (up to about 1000 N / cm ² or 100 bar) and at the same time high temperatures (up to about 220 ° C) through a lamination process. Sandwich press pads contain a reinforcing layer of fibers, for example, in the form of a fiberglass fabric located in the middle, to reduce deformation both during operation of the press and when removing the finished pressed material, as well as picking a new billet for pressing, and thereby increase the service life press pillows. In addition, mold release pads for printed circuit boards often have release layers on their surface, for example, in the form of a film of polytetrafluoroethylene (PTFE). In addition, it is important during the operation of such high-pressure press pads to prevent abrasion of the fibers or particles of the press pads, since such abrasion would contaminate the material of the printed circuit board and, thereby, lead to a deterioration in its quality or even technical unsuitability.

In addition, press pillows are also very often used in the manufacture of wood-coated surface materials. Such laminates are used primarily in the field of furniture production and as floor materials. For example, on wood-fiber boards (“particle boards” or MDF boards - medium-density fiber boards), decorative layers are applied in the form of wear-resistant polymer films with a variety of decors (wood, ceramic tile, stone, etc.). ) The connection between the decorative layer and of the fiber board substrate is usually carried out using a melamine resin which is under pressure and the influence of temperature (compaction pressure up to 50 bar or 500 N / cm ² and pressing temperature 220 ° C) is brought to the curing press for lamination.

As with the use of press pillows in the field of production of printed circuit boards, and when applying decorative layers to the fibrous materials, press pillows perform the task of compensating for the tolerances of the thickness or, accordingly, the height in the area of the hydraulic press. Such thickness or height tolerances arise due to dimensional deviations in the area of the material being pressed (fiber board or decorative film or, respectively, the starting materials for the printed circuit boards), however, primarily in the area of the press itself. Thus, the dimensions of heated upsetting plates of press plants are usually several meters, so that, along with manufacturing tolerances during operation of the press, there are also problems with warping of plates due to different temperature distributions. Even so-called press gaskets, which come into contact with the material to be pressed on both sides, dimensional tolerances can occur. Thus, the first important property of the press pads is to compensate for such dimensional tolerances in the area of the system “heated plate - press pad - pressed material - press pad - heated plate”. In order to be able to carry out such a compensation of the thickness for a long time without damaging the press pad, the press pad must have sufficient elastic, i.e. springing properties, which, once the pressure is relieved, again return it to its original shape. Typically, in known press cushions, elastomeric materials are used to obtain the desired spring properties. In particular, silicone elastomers, or fluoroelastomers, or fluorosilicon elastomers are often used in press cushions due to their good heat resistance and resistance to various chemical substances.

Since press cushions must have good thermal conductivity, which only generally provides the necessary fast heat flow from the heated plate through the press cushion and press gasket into the pressed material, press cushions regularly include components of well heat-conducting materials, in particular metals. Often for this purpose copper and / or brass and / or stainless steel and / or other metal alloys are used.

Basically, among the known press pillows, press pillows, which are flat-shaped textile products, and press pillows, which include a continuous layer of material, should be distinguished. A press pad including a continuous layer of material is known, for example, from DE 2319593 A or EP 1300235 A. In order to ensure their integrity for a long time also at high pressing pressures, as well as during handling of the press pads, Support fabric, for example, made of bronze threads, is introduced into the used silicone elastomer. In order to increase thermal conductivity, a press part according to EP 1300235 A has a surface portion of a metal supporting fabric protruding above the elastomeric material. To further increase thermal conductivity, particles with high thermal conductivity (metal powder, quartz powder) can also be introduced into the elastomeric material. As already indicated, in addition, many press pillows are textile products of a flat shape, which, in particular, can be made in the form of fabric, knitwear or non-woven material. Thus, only due to the geometry of the press cushion or, accordingly, the fibers incorporated into it, is a good shape-changing ability and therefore good thickness compensation. This is true, first of all, when the filaments have high intrinsic elasticity in the direction transverse to their longitudinal axis, in particular, consist of an elastomeric material or, accordingly, include a tensile core thread (metal or polymer fiber) that is coated sheath made of elastomeric material. Such press pads are known, for example, from EP 0735949 A, EP 1136248 A and EP 1779999 A in the form of woven press pads. Knitted press pads are described in particular in EP 1033237 A, EP 1040910 A and EP 1040909 A. In order to give the press pad a particularly good point elasticity, the alternating use of threads equipped with an elastomer sheath is known from EP 1386723 A, whose elasticity across the longitudinal axis of the thread is alternately higher or, accordingly, lower. In addition, press pillows or, respectively, press pillow-press gasket combinations are known in which the interconnected cavity of the press pillow or combination is filled with fluid material at press operating temperature (EP 2189276).

A disadvantage of press pillows made in the form of mats, known from DE 2319593 A, is their relatively high stiffness and insufficient point elasticity. In contrast, press pillows, which are made in the form of textile products of a flat shape, are relatively expensive to manufacture. This is true, in particular, when sheathed filaments are used, possibly of various kinds, for which, in the first step, the core filament material must be provided with an elastomeric sheath material during the extrusion process. The textile technical processing (textile or knitting) carried out in the second step also requires high costs, since the processed elastomeric threads or, accordingly, metal threads, in contrast to classical textile materials, are more difficult to process and at a lower speed.

The basis of the invention is to propose a press pad, which is characterized by good point elasticity while at the same time simple manufacturing capabilities.

Based on the press cushion of the aforementioned kind, the problem underlying the invention is solved due to the fact that the first layer on its side facing the second layer is provided with a plurality of channels in which there is a fluid material at least at the operating temperature of the press and which are closed at least the second layer is impervious to fluids.

By means of the location and size of the channels, individual and simple regulation of the elastic properties of the press pad over its area is possible. Also, due to the elastic properties of the elastomeric material, on the one hand, and fluid at the operating temperature of the press material in the channels, on the other hand, it is possible to vary the properties of the press cushion in accordance with the invention in a very wide range. In addition, it is possible to easily realize various effective elastic properties in different zones of the press pad.

According to one preferred embodiment, in addition to the first and second layers, a third layer is provided which is connected to it on the side of the first layer facing away from the second layer and is also impermeable to fluids. In this case, either the first layer is also provided with another set of channels on its side facing the third layer, or the third layer is provided with another set of channels on its side facing the first layer. In the latter case, the third layer, like the first layer, includes an elastomeric material and fibers connected to it. In each case, another plurality of channels is closed by the connection between the first layer and the third layer, which is impervious to fluids.

Thus, in the above-described manner, two levels of channels are formed, due to which the possibilities of configuring the distribution of elasticity as well as the characteristic of elasticity are further increased.

Typically, a press pad according to the invention, modeled on existing press systems, is rectangular and at least in one edge region, preferably in all edge regions in a circumferential direction, has no channels. The width, depending on the corresponding format of the heated plate, of at least one edge region is preferably from 1 cm to 20 cm. In the above-mentioned edge regions, it is possible in a simple way to create a full-surface continuous connection between the first layer and the second layer or, respectively, between the first layer and the third layer, since contact over a relatively large area can be realized. Therefore, the edge regions are suitable, in particular, for closing the channels in their end direction, in order to achieve fluid tightness in this direction as well.

It is particularly preferred that the first layer and the second layer and / or the first layer and the third layer are glued or welded to each other, in particular, laser welding or ultrasonic welding is also preferably possible.

In one preferred embodiment of the invention, the plurality of channels includes a first group of channels that run parallel to each other, preferably a second group of channels that, in turn, runs parallel to each other and perpendicular to the channels of the first group. In this case, it is possible that the channels of both groups communicate with each other or not. In the first of these cases, there arises, therefore, a system of channels crossing and connected to each other. Then these channels are distributed preferably in the same plane or, accordingly, form a single "layer of channels". If these two groups do not communicate with each other, they, when viewed in the direction of the thickness of the press pad, are preferably spaced apart, so that two separate “layer of channels” are obtained. In crossing channel groups, a particularly homogeneous distribution of the channels over the area of the press pad is achieved, so that the local deviations in the elasticity of the press pad can be small.

As for the manufacture of the press pad according to the invention, the channels can be made in the corresponding layer according to the prototyping technology, in particular by casting or doctor blade into the appropriate form, or by the processing technology, in particular by embossing, stamping or cutting, or with material removal , in particular by laser processing or milling. In order to obtain a particularly well-calculated characteristic of the elasticity of the press pad over its entire area, a certain number of channels or, accordingly, all channels must be completely filled with fluid material at the operating temperature of the press. By “fluid flowing at the operating temperature of the press material” is meant any fluid, that is, both a compressible fluid (gas) and any incompressible fluid (liquid). The material may be at temperatures below the operating temperature also in the solid state of aggregation. As the fluids for the press-cushion according to the invention, in particular, air or other (inert) gases, or oils (mineral or synthetic oils or mixtures thereof), or (inert) liquids, or metals with a low melting point are considered. This is, in particular, lead or tin, or alloys that contain at least one of the above elements, and which at room temperature may be in a solid state of aggregation.

While many channels can also partially be located both in the first and second layers, and in the first and third layers due to a simpler manufacturing ability, it is especially preferred if the second layer and / or third layer is a film with a thickness of 10 μm to 1000 μm and includes a polymer or consists of a polymer, preferably, for example, polytetrafluoroethylene (PTFE) or fluororubber, or silicone or fluorosilicon elastomers. In order to ensure the integrity of the press pad for a long time, even under high constantly changing pressure loads, the first layer and / or second layer and / or third layer may include a backing fabric that is embedded in an elastomeric material, preferably a silicone elastomer, or a fluoroelastomer, or a fluorosilicon elastomer, or a composite elastomer containing at least two of the above elastomers. A measure that enhances the stability of the press pad may be that the fibers contained in at least the first layer are high-temperature polymer fibers, in particular fibers of aramid, Kevlar, polyester, melamine resin, carbon fiber, glass, or metal wire, in particular wire made of brass, copper, stainless steel. Moreover, these fibers can be in the form of monofilament or multifilament yarns, and preferably the fibers are in the form of individual staple fibers with a length of 1 mm to 50 mm and / or in the form of a textile product of a flat shape, in particular fabric, knitwear, knitted fabric, non-woven material or mesh cloth.

Since elastomeric materials are inherently more likely to have moderate thermal conductivity, the elastomeric material of the first layer and / or third layer and / or fluid at the operating temperature of the press may contain particles with high thermal conductivity, in particular metal powder or silica powder. Thus, in particular, for press plants that are operated with a short cycle time, it is possible to accelerate the transfer of heat to the material being pressed, due to which, in turn, a lower temperature of the heated plates can be selected.

Typically, the proportion of the area of the channels relative to the total area of the press pad is preferably from 5% to 50%, preferably from 10% to 20%. If channels are located in several “channel layers”, it is necessary to consider channels in all layers. If the channels are located congruently on top of each other in several layers, when calculating the above fraction of the area, only the channels of one single layer should be taken into account.

While the distribution of channels in the area of heated plates or, respectively, press linings for “unproblematic” press systems is most often uniform, for problematic press systems with different pressure distributions, uneven channel distribution can be deliberately provided. This unevenness may be such that in certain areas of the press pad, the distance between adjacent channels is greater or less than in other areas of the press pad, and / or in certain areas of the press pad, the dimensions of the channels, in particular their width and / or depth more or less than other areas of the press pad.

Finally, in accordance with the invention, it is also provided that the channel width is from 5 mm to 20 mm, and / or the channel depth, measured in the direction perpendicular to the surface of the press pad, is from 1 mm to 5 mm, and / or the distance to the light between adjacent parallel channels is from 1 mm to 50 mm.

Below the invention is explained in more detail using several examples of the implementation of the press pillows, which are shown in the drawings.

Shown:

figure 1: a vertical section of a press with heated plates,

figure 2: a vertical section of a first embodiment of a press pad in an exploded view,

figure 3: vertical section of a second variant of implementation of the press pillows

4: a vertical section of a third embodiment of a press pad,

FIG. 5: a perspective view of a first layer of a press pad shown in FIG. 3, and

Fig.6: top view of the angular region of the first layer of the press pillow shown in Fig.3.

Schematically depicted in figure 1, the press 1 has a mirror-symmetric design with respect to the horizontal central plane 2 and includes two heated plates 4 provided with a plurality of heating channels 3, as well as two metal press gaskets 5, which are facing each other, in particular engraved , surfaces facing the center of the pressed material. The pressed material is, for example, intended for coating an MDF plate, coated on both sides with a decorative film, which must be connected to the MDF plate by means of melamine resin under the influence of pressure and temperature.

To compensate for the thickness tolerances in the pressed material 6, as well as other height differences, both in the press pads 5 and in the heated plates 4 (for example, due to warping), there is a press pad 7 between each press pad 5 and the corresponding heated plate 4. The press pad is issued by the edge regions 8 on all sides for a rectangular heated plate 4 and a press pad 5 having the same size, which serves for fastening purposes.

The design of the press cushion 7 is shown in more detail in a vertical section in figure 2. The press pad 7 is shown in a kind of exploded view in which the central first layer 9 and the upper second layer 10, as well as the lower third layer 11 are located for distance from each other for clarity. However, in reality, the above-mentioned three layers 9, 10, 11 are firmly and, in particular, impervious to fluids connected to each other, which will also be explained in more detail below.

The press cushion 7, as well as the first layer 9, are symmetrical with respect to the central plane 2. In the central plane 2, inside the first layer 9, there is inserted into its elastomeric material, in particular silicone elastomer, the plain fabric 12, from which the wave-like main thread and the trimmed weft threads are visible. Above the upper side 13 of the first layer 9 and under the lower side 14 of the first layer 9 are the second layer 10 and the third layer 11.

An essential feature of the invention of the press pad 7 is the presence of a first plurality of channels 15 in the upper side 13 of the first layer 9 and, in the case of the present embodiment, also a second plurality of channels 16 in the lower side 14 of the first layer 9. Both channels 15 and channels 16 pass respectively inside their "group", but also with respect to the channels 15, 16 of both groups parallel to each other, and are equidistant relative to each other. The channels 15 in the upper side 13 of the first layer 9 are located with an offset of half the distance to each of the adjacent channels 15, 16, so that a characteristic arrangement is obtained “in a checkerboard pattern”.

In order to obtain channels 15, 16 closed by fluid tightness, the upper side 13 of the first layer 9 is glued or welded to the second layer 10. A possible adhesive layer of known adhesive is not shown in the drawings, for simplicity's sake. The second layer 10 is a film, for example, of silicone elastomer. The same, with reference to the lower side of the press pad 7, is true for connecting the third layer 11 to the lower side 14 of the first layer 9. As will be described later in more detail with reference to another embodiment of the invention, the edge regions of the press pad 7 in circumferential direction do not have channels 15, 16, so that the latter are also closed from the end side impervious to fluids. In the present case, the press pillows 7 channels 15, 16 are filled with air. But it is also possible to fill with any other gas, as well as filling with any liquids, or metal, or, respectively, a metal alloy, which, or, respectively, which is in a liquid state at a press operating temperature (equal to approximately 80 to 220 ° C).

In contrast to the three-layer structure, in accordance with FIG. 2, the press pad 17 shown in FIG. 2 has only a two-layer structure. There is a fluid tight connection between the first layer 19 and the second layer 20. Starting from the upper side 21 of the first layer 19, channels 22 are located in the first layer 19. The channels 22 extend parallel and equidistantly at a distance of 23 from each other in a direction measured in parallel upper side 21 of the press pad 17.

The depth of 24 channels 22 (measured from the upper side 21 of the first layer 19) is approximately 1 mm. Measured perpendicular to depth 24, width 25 is 2 mm. The thickness 26a of the first layer 19 is 2 mm, in contrast to which the thickness 26b of the second layer 20 is approximately 1 mm.

From the view shown in FIG. 5, it is understood that the press pad 17 shown in FIG. 3 includes not only the first group of channels 22 parallel to each other, but also the second group extending perpendicular to them, within the second group passing parallel and equidistant channels 28. Thus, a kind of checkered pattern is formed on the upper side 21 of the first layer 19.

Figure 6 clearly shows that the peripheral edge regions 30 of the press pad 17 do not have channels. The edge regions 29, 30 have a width of 31, 32 of approximately 1 cm. The edge regions 29, 30 preferably extend beyond the heated plates 4 and press pads 5 of the press 1 on the sides and, thus, in contrast to the central part provided with channels 22, 28 the press pads 17 are not in the area of transmission of pressure forces during the operation of the press. Due to the presence of edge regions 29, 30, the channels 22, 28 end in front of the edges 33, 34 of the press pad 17 and thus provide a fluid tight channel closure of the channels 22, 28 from the front side.

One of the alternative embodiments of the press cushion 27 is shown in vertical section in figure 4. The press pad 27 consists of a first layer 39 and is impervious to fluids of a second layer 40 adhered thereto, which both consist of an elastomeric material, in particular a silicone elastomer, and both have the same thickness 35 of approximately 1 mm.

The passing channels 36 of the press pillow 27 equidistantly and parallel to each other in cross section are round in shape and respectively made half in the first layer 39 and the second layer 40. In each layer 39, 40 there are, therefore, half channels that are semicircular in cross section, which when combined with the identical construction of the first and second layers 39, 40 into a full channel 36 complement each other, forming a circular cross section. Therefore, in the manufacture of the press pad 27, on the one hand, it is important that the distance 38 between adjacent channels 36 is exactly the same and that the fluid tight connection of the first and second layers 39, 40 is made exactly so that the channels 36 form a circular cross section. The diameter of the 37 channels 36 is 1.5 mm, which, with a total thickness 41 of the press pad equal to 3.5 mm, corresponds to a fraction (length) of approximately 43%.

The elastomeric materials of all of the above-mentioned press pads 7, 17, 27 can be provided with particles of a heat-conducting material, in particular a metal powder, to increase thermal conductivity. The same is true also for the material with which the channels 15, 16, 22, 28 are filled, presumably representing a liquid, such as, for example, oil.

Item Specification

1 Press

2 Center plane

3 Heating channel

4 Heated stove

5 Press pad

6 Pressable material

7 Press cushion

8 Marginal area

9 first layer

10 second layer

11 Third layer

12 Support fabric

13 Upper side

14 Bottom side

15 Channel

16 Channel

17 Press cushion

18a Thickness

18b Thickness

19 Layer

20 layer

21 Upper side

22 channel

23 Distance

24 Depth

25 Width

26a Thickness

26b Thickness

27 Press cushion

28 channel

29 Regional area

30 Regional area

31 Width

32 Width

33 edge

34 edge

35 Thickness

36 Channel

37 Diameter

38 Distance

39 First layer

40 second layer

41 Thickness

Claims (16)

 1. A press pad (7, 17, 27) of a hydraulic press (1) containing a first fluid tight layer (9, 19, 39) that contains an elastomeric material and fibers connected thereto, and connected to said first layer ( 9, 19, 39) a second fluid-tight layer (10, 20, 40), characterized in that the first layer (9, 19, 39) is made with channels (15, 22, 28, 36) facing the second layer (10, 20, 40) to the side in which the material, at least at the operating temperature of the press (1), is located, said channels being closed by at least measure of the second layer (10, 20, 40) with the provision of impermeability to fluids. 2. A press pad according to claim 1, characterized in that it comprises a third layer (11) that is connected to the first layer (9) on its side facing away from the second layer (10) and is impermeable to fluids, the first layer being (9) on its side facing the third layer (11) is made with other channels (16), and / or the third layer on its side facing the first layer is made with other channels and contains elastomeric material and fibers connected to it, while the channels (16) are closed by the connection between the first layer (9) and the third layer (11) with impermeability to fluids. 3. A press pad according to claim 1, characterized in that it is rectangular, with at least one edge region (29, 30), preferably all edge regions (29, 30) of the press pad (7, 17, 27 ) in the circumferential direction, made without channels (15, 16, 22, 28, 36), and the width (31, 32) of at least one edge region (29, 30) is preferably from 1 to 20 cm. 4. A press pad according to claim 1 or 2, characterized in that the first layer (9, 19, 39) and the second layer (10, 20, 40) and / or the first layer (9) and the third layer (11) are glued or welded together. 5. A press pad according to claim 1, characterized in that the channels (22, 28) include a first group of channels (22) that are parallel to each other, and preferably a second group of channels (28) that are parallel to each other and perpendicular channels (22) of the first group. 6. A press pad according to claim 1 or 2, characterized in that the channels (15, 16, 22, 28, 36) are made in the corresponding layer according to the technology of prototyping by casting or doctor blade method in the corresponding form, or by technology of pressure processing by the method embossing, stamping or cutting, or with the removal of material by laser processing or milling. 7. Press cushion according to claim 1 or 2, characterized in that part of the channels or all channels (15, 16, 22, 28, 36) are completely filled with material flowing at the operating temperature of the press (1). 8. A press pad according to claim 1 or 2, characterized in that a gas, in particular air or an inert gas, or a liquid, in particular oil, is used as the fluid material located in the channels (15, 16, 22, 28, 36). or an inert liquid, or metal, which is solid at room temperature and at press operating temperature (1) in an aggregate liquid state, in particular lead, tin or an alloy containing lead and tin. 9. A press pad according to claim 1 or 2, characterized in that the second layer (10, 20, 40) and / or the third layer (11) is made in the form of a film with a thickness of 10 μm to 1000 μm and contains a polymer, for example silicone elastomer. 10. A press pad according to claim 1 or 2, characterized in that the first layer (9, 19, 39), and / or the second layer, and / or the third layer (11) contains a supporting fabric (12), which is introduced into an elastomeric material, preferably a silicone elastomer, or a fluoroelastomer, or a fluorosilicon elastomer, or a composite elastomer containing at least two of the above elastomers. 11. A press pad according to claim 1, characterized in that the fibers contained in the first layer (9, 19, 39) are high-temperature-resistant polymer fibers, in particular fibers from aramid, melamine resin, nomex, kevlar, carbon fiber, glass, or metal wire, in particular wire of brass, copper, stainless steel, aluminum. 12. The press pad according to claim 1, characterized in that the fibers contained in the first layer (9, 19, 39) are made in the form of monofilament or multifilament yarns, preferably in the form of individual staple fibers with a length of 1 to 50 mm, and / or in the form of a textile product of a flat shape, in particular fabric, knitwear, knitted fabric, nonwoven fabric or mesh fabric. 13. A press cushion according to claim 1 or 2, characterized in that the elastomeric material of the first layer (9, 19, 39) and / or the third layer (11) and / or fluid at the operating temperature of the press (1) contains materials particles with high thermal conductivity, in particular metal powder or silica powder. 14. The press pad according to claim 1 or 2, characterized in that the proportion of the area of the channels (15, 16, 22, 28, 36) relative to the total area of the press pad (7, 17, 27) is from 5 to 50%, preferably from 10 to 30%. 15. The press pad according to claim 1, characterized in that the channels are distributed unevenly over its area, while the press pad is made with areas in which the distance between adjacent channels is larger or smaller than in other areas, and / or the dimensions of the channels in particular, their width or depth is greater or less than in other areas. 16. The press pad according to claim 1 or 2, characterized in that the width (25, 37) of the channels (15, 16, 22, 28, 36) is from 5 to 20 mm and / or the depth (24) of the channels (15 , 16, 22, 28, 36), measured in the direction perpendicular to the surface of the press pad, is from 1 to 5 mm, and / or the distance (38) between adjacent parallel channels (36) is from 1 to 50 mm.

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