ROLLER SCALE AND CONTINUOUS PRESS

Description

[0001] The invention relates to a roller bar as a rolling element assembly for a continuous press with endlessly circulating press belts (in particular steel belts), which are supported against (heatable) press plates of the continuous press by means of the roller bars, wherein the roller bar is cylindrical and made of, for example, steel (with a predetermined length and diameter) with a cylindrical shell and end faces. Preferably, bearing bores are arranged in the end faces, into which roller bar bearing pins can be inserted or are inserted.

[0002] These rollers are therefore used as rolling element assemblies in a continuously operating press. Such a continuously operating press is preferably used within the scope of the invention for the production of wood-based panels. Wood-based panels refer in particular to fiberboard, particleboard, or OSB panels. Alternatively, the invention also relates to the production of composite panels or composite components. Composite panels or composite components refer in particular to those made of a fiber-reinforced composite material, e.g., SMC (sheet molding compounds) or organosheets.

[0003] A continuous press has an upper heated press plate (upper heating plate) in the press upper section and a lower heated press plate (lower heating plate) in the press lower section, as well as optionally projecting inlet plates. Endless circulating press belts, e.g., steel press belts, are guided in the press upper and lower sections and supported against the press plates / heating plates by means of roller bars. The roller bars are connected to roller bar chains or circulating chains, which are designed, for example, as link chains, by means of end-mounted roller bar bearing pins. The diameter of the roller bars is typically 15 mm to 25 mm. The roller bar length is, for example, between 2 m and 2.5 m.

[0004] Continuous presses of this type using rolling bars have long been established in practice. The material to be pressed is compressed in the press gap between the circulating steel belts using pressure and heat. The circulating steel belts are supported on the heated press plates by the interposed rolling bars, allowing the rolling bars to roll along the press plates as rolling element assemblies. Due to typical manufacturing tolerances or minimal deviations of the rolling bar shape from a perfect cylinder, differences in displacement or length can occur at the two outer ends of the rolling bars during the rolling motion. These differences are compensated for by "micro-slip." Therefore, it is common practice and necessary to lubricate the rolling bars and their cylindrical surfaces with a liquid lubricant. Such a lubricant is used, for example, in...The lubricants are sprayed onto the rollers using nozzles in the inlet area or during roller bar circulation. These measures have proven effective in practice, but the use of such lubricants involves corresponding operating costs. Furthermore, the operating range of these lubricants is limited with regard to temperature. This is where the invention comes in.

[0005] The invention is based on the objective of creating a roller bar which enables particularly economical operation of a continuously operating press and is especially suitable for higher application temperatures.

[0006] To solve this problem, the invention teaches, in the case of a generic rolling rod of the type described above, that at least the cylindrical surface is provided with a self-lubricating (and consequently friction-reducing) coating over its entire length and circumference. Additionally, one or both end faces can also be provided with such a self-lubricating coating, at least partially, and optionally completely. The coating according to the invention is made of tungsten carbide. Alternatively, a coating of molybdenum disulfide is also used.

[0007] The invention is based on the understanding that the use of liquid or free-flowing lubricants in the area of ​​the rollers of a continuously operating press can be completely eliminated if the rollers are self-lubricating with a (dry-lubricating) coating and thus exhibit inherent lubrication. Such coatings, e.g., tungsten carbide (WCH) coatings or molybdenum disulfide (MoD) coatings, are generally known. They are characterized by very low coefficients of friction and low adhesion tendencies combined with good wear resistance. Tungsten carbide-based coating systems with lamellar, dry-lubricating graphitic inclusions have become established, for example, in components of the automotive industry and in the field of gears.

[0008] While DE 10 2005 009 298 B4 already proposed the use of carbon-based coatings, such as WCH coatings, in the area of ​​the spherical bearings of cylinder-piston assemblies in a continuous press, the present invention focuses on optimizing the roller bars in a continuous press, which are subject to particularly high loads and potentially high temperatures during continuous operation. This is because the pressing pressure is generated by the press cylinders typically used in a continuous press, with the aid of the upper or lower heating plate. This pressure is then transmitted to the workpiece via the press plates, with the roller bars and steel belts interposed, during the rolling motion of the roller bars under high load between the respective steel belt and the respective heating plate, and at high temperatures.Document DE 10 2009 013773 discloses a rotationally symmetrical component for rolling mills in the metallurgical industry, which is coated with a nickel-phosphorus dispersion coating containing tungsten carbide particles.

[0009] By using the self-lubricating coating according to the invention, the use of conventional free-flowing lubricants can initially be dispensed with (or at least reduced), thus enabling particularly economical operation of the continuous press.

[0010] A further advantage of the solution according to the invention is the fact that a self-lubricating coating, such as a WCH coating or molybdenum disulfide coating, is very temperature-resistant, making the press suitable for higher temperatures and, if necessary, high-temperature applications. Consequently, the roller bars according to the invention can be used not only in presses for the production of wood-based panels, which are typically operated with heating platen temperatures of around 200°C, but alternatively, the roller bars according to the invention can also be used in continuous presses for the production of composite components that are pressed at higher temperatures. These can be, for example, fiber-reinforced composites and, particularly preferably, SMC (Sheet Molding Compounds).

[0011] However, significant advantages can also be achieved with the roller bars according to the invention during the production of wood-based panels (e.g., particleboard, fiberboard, or OSB panels). A substantial reduction in costs is achieved through a significantly reduced or even eliminated consumption of lubricants or oil. Furthermore, it is also possible to increase the operating temperature of the press plates / heating plates when manufacturing wood-based panels, so that the material is pressed at higher temperatures, thus reducing the heating time factor. This, in turn, leads to higher output and therefore greater efficiency with the same press length. For example, wood-based panels can be pressed with heating plate temperatures exceeding 230°C, e.g., more than 250°C.

[0012] The invention also relates to a continuous press with the rollers according to the invention, as well as a method for pressing mats or similar materials in a continuous press of the type described, wherein, according to the invention, rollers are used that are provided with a self-lubricating coating, so that the method according to the invention particularly preferably eliminates the need for liquid lubricants in the area of ​​the rollers. This method is suitable, for example, for the production of wood-based panels at particularly high temperatures, e.g., heating plate temperatures of more than 230°C, e.g., more than 250°C. According to the invention, the method is also suitable for the production of components made of composite materials, e.g., fiber-reinforced composites, at heating plate temperatures of more than 300°C.

[0013] The self-lubricating coating according to the invention is preferably applied by deposition from the vapor phase or from the plasma phase. Consequently, a plasma-assisted physical vapor deposition (PVD) process is used for the coating. This is a vacuum coating process in which the starting materials are converted from the solid phase to the gas phase or ionized by the input of thermal or kinetic energy. The coating is thereby introduced intergranularly into the surface of the rolling bars (which are preferably made of steel).

[0014] Preferably, the guide rollers for the circulating chains are provided with roller bearing pins on their end faces, which engage in corresponding recesses in the chains. Preferably, the rollers have bearing bores in their end faces into which the roller bearing pins can be inserted or are inserted. However, the invention also includes other designs that enable rotatable guidance within the chains.

[0015] The invention will now be explained in more detail with reference to a drawing that illustrates only one embodiment. The drawing shows... Fig. 1 shows a continuously operating press in a simplified representation and Fig. 2 shows a roller bar for a continuous press according to Fig. 1 .

[0016] In Fig. 1 Figure 2 shows a continuously operating press suitable, for example, for pressing mats of material into panels during the production of particleboard, fiberboard, or other wood-based panels. The basic structure of the continuous press 2 comprises an upper press section with an upper, heated press platen and a lower press section with a lower, heated press platen 4. The press plates 4 are also referred to as heating plates. In both the upper and lower press sections, endlessly circulating press belts 3 (e.g., made of steel) are guided, forming a press gap 5. The steel press belts 3 are supported against the press plates 4 by means of roller bars. The roller bars 1 are guided by means of roller bar bearing pins on endlessly circulating roller bar chains, which are not shown in the figures.The roller bar 1 itself is cylindrical and made of steel with a predetermined length L and diameter D. It has a cylindrical shell 6a and end faces 6b. In this embodiment, bearing bores 7 are provided in the end faces 6b of the roller bar 1. Roller bar bearing pins can be inserted into these bearing bores 7, or are already inserted, but these are not shown in the figures. The roller bars 1 are guided in the continuous press 2 by these roller bar bearing pins, which are designed, for example, as link chains.

[0017] According to the invention, at least the cylindrical shell 6a of the roller bars 1 is provided over its entire length and circumference with a self-lubricating coating, which can be a tungsten carbide coating or a molybdenum disulfide coating. Such a coating can be applied to the roller bar surface, for example, by a plasma process. The coating 8 is in Fig. 2 This is only a simplified description. Such a coating 8 provides inherent lubrication of the rollers, thus reducing the need for conventional free-flowing lubricants. Preferably, free-flowing lubricants are completely eliminated.

[0018] The layer thicknesses of the coatings 8 can, for example, be 1µm to 15µm within the scope of the invention.

Claims

1. Roller rod (1) as a roller body assembly for a continuously operating press (2) with continuously circulating press belts (3), wherein the roller rod (1), e.g. made of steel, is designed cylindrically with a cylinder jacket (6a) and end faces (6b), characterised in that at least the cylinder jacket (6a) is provided over the entire length (L) and the entire circumference of the roller rod with a self-lubricating coating (8) of tungsten carbide or molybdenum disulphide.

2. Roller rod according to claim 1, characterised in that one or both end faces (6b) at least in parts are provided with a self-lubricating coating.

3. Roller rod according to claim 1 or 2, characterised in that the coating is applied through deposition from the vapour phase or plasma phase.

4. Roller rod according to any one of claims 1 to 3, characterised in that bearing holes (7) are arranged in the end faces (6b) into which roller rod bearing bolts are insertable or inserted.

5. Continuous press (2), more particularly for the manufacturing of wood based boards, composite boards or composite components, with an upper heatable press plate (4) and a lower heatable press plate (4) with continuously circulating press belts (3) which with the interposition of roller rods (1) according to any one of claims 1 to 4, are supported on the press plates (4), and wherein the roller rods (1) are bilaterally guided on roller rod chains.

6. Method for the pressing of pressing material mats or similar pressing materials in a continuous press according to claim 5, more particularly for the manufacturing of wood based boards, characterised in that within the continuous press, roller rods with a self-lubricating coating according to any of claims 1 to 4 are used.

7. Method according to claim 6, characterised in that the pressing material mats are pressed into wood based boards at a press plate temperature of greater than 230° C, preferably greater than 250° C.