TIP PLATE AND CORRESPONDING BUSHING

Abstract

The invention relates to a tip plate for a bushing for receiving a high temperature melt, which tip plate comprises several sections of different type, while the invention further includes a corresponding bushing to produce glass fibres.

Claims

1. Tip plate (TP) for a bushing (BU) for receiving a high-temperature melt (GM), comprising—in its operational position—an upper surface (US), which extends in an x-y-direction of the coordinate system, a lower surface (LS) at a distance (d) to the upper surface (US) and a body (BO) in between, as well as a multiplicity of nozzle like through-openings (NO), extending at least between the upper surface (US) and the lower surface (LS), through which the melt (GM) may leave the bushing (BU) in a z-direction of the coordinate system, wherein at least two sections (A-B, B-C, C-D, D-E, F-G, G-H, H-J) of the tip plate (TP), adjoining each other in the x-y-direction of the coordinate system, have different physical properties, different chemical composition or both.

2. Tip plate (TP) according to claim 1, wherein at least one section (A . . . J) is produced by additive manufacturing.

3. Tip plate (TP) according to claim 2, with at least 50% of its volume produced by additive manufacturing.

4. Tip plate (TP) according to claim 1, wherein the upper surface (US) is a closed surface with the exception of the areas of the through openings (NO).

5. Tip plate (TP) according to claim 1, wherein at least one depression (DE) extends from the lower surface (LS) of at least one section (F) into the body (BO).

6. Tip plate (TP) according to claim 1, wherein at least one section (A, B, D, E, G, H) below the upper surface (US) features at least one hollow space (CP).

7. Tip plate (TP) according to claim 1, wherein at least one section (F) below the upper surface (US) features a lattice structure.

8. Tip plate (TP) according to claim 1, wherein the distance (dJ) between the upper surface (US) and the lower surface (LS) of at least one section (J) is different to the distance (dH) between the upper surface (US) and the lower surface (LS) of at least one adjoining section (H).

9. Tip plate (TP) according to claim 1, wherein at least two adjoining sections are made of different metal alloys.

10. Tip plate (TP) according to claim 1, comprising at least ninety mass percent of a PtRh alloy.

11. Bushing (BU) for receiving a high-temperature melt (GM), comprising a tip plate (TP) according to claim 1 and at least one wall (W1,2), extending from said tip plate (TP) into the z-direction.

12. Bushing (BU) according to claim 11, wherein the tip plate (TP) has a rectangular shape in a top view and four wall segments (W1, W2) extending therefrom in the same direction, thus limiting a cuboid space for the melt (GM), wherein the wall segments (W1, W2) are tightly connected to the tip plate (TP).

13. Bushing (BU) according to claim 11, with at least two wall segments (W1, W2) being arranged at a distance to each other and connected to an electric power supply (F1, F2).

14. Bushing (BU) according to claim 10, wherein at least one section (A . . . J) of the tip plate (TP) is produced by additive manufacturing.

15. Bushing (BU) according to claim 10 with a tip plate (TP) produced by additive manufacturing.

Description

[0061] The invention will now be described in more detail by reference to the attached schematic drawing, featuring the following:

[0062] FIG. 2: a vertical cross section of a bushing according to the invention, including embodiments F-J of a tip plate according to invention

[0063] FIG. 3: side and top views according to FIG. 1 of a tip plate according to the invention

[0064] FIG. 4: a further embodiment of a tip plate according to the invention in a cross sectional presentation.

[0065] In the Figures the same parts or parts of substantially equivalent function or behavior are characterized by the same numerals.

[0066] FIG. 2 displays a bushing BU which comprises a rectangular (bottom) tip plate TP with an upper surface US and a lower surface LS, between which the tip plate TP defines a body BO and through holes designed as corresponding nozzles NO, as well as four side walls, two of which (W1, W2) are displayed, together defining a space for a glass melt GM, present on the upper surface US and extracted therefrom via said nozzles NO (the flow—by gravity—and the flow direction substantially correspond to the z-direction, see attached coordinate system).

[0067] Side wall W1, W2 and tip plate TP are made of a PtRh alloy (90 m % Pt, 10 m % Rh) and welded to each other.

[0068] Tip plate TP was designed by additive manufacturing, i.e. in a 3D laser printer, by forming one thin layer of a fine alloy powder (particles<100 μm] on top of the other in successive manufacturing steps and melting the powder material by laser beams according to a predefined pattern until the final design has been reached.

[0069] FIG. 2 schematically displays four embodiments of possible designs for the tip plate TP, named F to J, which can be realized individually or in arbitrary combinations, depending on the specific glass melt, electric power and overall sizes of the bushing.

[0070] Section F is characterized as follows:

[0071] Below the “closed” upper surface US is a section featuring a lattice structure, defined by thin partition walls PW arranged in a zig zag pattern and substantially “open” downwardly, i.e. in this embodiment the lower surface LS of the tip plate is defined by an imaginary surface IS, (generally parallel to the upper surface US), from which depressions extend upwardly, in the z-direction, towards the upper surface US.

[0072] Section F requires ca. 30% less alloy material compared with a solid section, although its mechanical strength is very high. The thermal behavior is such that section F achieves a higher temperature compared with a solid plate construction.

[0073] This design may, for example, be used in the hot spot area (C) of a tip plate TP similar to that of FIG. 1.

[0074] Section G differs from section F by a substantially closed lower surface LS, so that a thickness dG may be defined between upper and lower surface US, LS. The body material of section G is characterized by closed pores CP, which lower the density and weight of this section G compared to a throughout solid body material as used in prior art (FIG. 1). The number and size of said pores is only schematic and may be selected according to the local requirements.

[0075] Section H is similar to section G (thickness of section H=dG) but its structure features pores merging into each other, thus giving this section a sponge like structure.

[0076] Section J starts from a solid tip plate design, but is of substantially reduced thickness (dJ=0.7 dG), allowing a 30% material reduction and cost reduction as well as an increase in temperature compared with a solid tip plate section of a thickness dG.

[0077] All sections of the tip plate of FIG. 2 can be produced by additive manufacturing, either separately or in one common manufacturing process.

[0078] Generally: sections of different properties can follow each other not only in the x-direction as displayed, but alternatively or additionally also in the y-direction.

[0079] FIG. 3 displays the tip plate TP of generally same outer dimensions as that of FIG. 1, but the tip plate of FIG. 3 was produced by additive manufacturing (3D laser printing) and with different structural features in different sections (A-E).

[0080] As illustrated in FIG. 3a, sections A and E have been modified and now feature relatively large pores to lower the density and thus increase the temperature in that section (under the proviso of same electrical power as according to the embodiment of FIG. 1). The overall (closed) porosity of these sections A, E is around 20% by volume.

[0081] Adjoining sections B, D in FIG. 3 again differ from sections B, D of FIG. 1 by inner pores, but less than and smaller ones compared to sections A, E, so that the total (closed) porosity of sections B, D being around 10% by volume.

[0082] The center section C hasn't been changed between the embodiments of FIGS. 1 and 3.

[0083] The different structural features of the tip plate TP of FIG. 3, compared with that of FIG. 1, shows, that the tip plate TP of FIG. 3 features a substantially constant temperature profile (symbolized in FIG. 3c as T.A-E) between ends E1 and E2 (walls W1, W2), namely a temperature similar to that of section C in FIG. 1.

[0084] To lower this temperature (if required) and thus to increase the life time of the tip plate of FIG. 3, the power supply can now be reduced, which again saves costs.

[0085] FIG. 4a displays a very basic improvement over prior art according to FIG. 1 in that just the thickness of the tip plate TP is varied between opposite ends at W1,W2. While the shape of the upper surface US of the tip plate corresponds to that according to FIG. 1, the lower surface LS of the embodiment in FIG. 4 is designed in a curved way. Thickness dA in section A is the lowest and increases substantially continuously towards section C, which thickness dC being the largest in that embodiment (dC being ca. 1.5 dA) and then decreases again towards sections D and E, with dD being slightly larger (ca. 15%) than dA. Just by these means, which can be realized by additive manufacturing in a bespoke way without problems, the temperature distribution within the tip plate TP can be homogenized as displayed in FIG. 4b.

[0086] Generally spoken this embodiment is represented by a convex shape (curved, arched, cambered shape) of the lower surface and/or the upper surface of the tip plate in any/all direction(s) of the coordinate system. In other words: The tip plate may also feature a curved upper surface in the y-direction (and not only in the x-direction as shown). A smooth surface without steps is preferred to achieve a most homogeneous temperature distribution and strength within a tip plate of this embodiment defined by variations in its thickness. Further features of the invention as disclosed in connection with FIG. 2,3 may also be integrated into this embodiment.

[0087] Nozzles NO in all Figures have been displayed in a highly schematic way for better illustration. Typically up to 8000 nozzles (tips) are arranged within one tip plate.

[0088] The advantages of the new design are as follows: [0089] it requires much less material and thus is much cheaper [0090] it leads to a substantially homogeneous temperature distribution over the complete surface area [0091] it is much more precise in its dimensions [0092] the nozzles NO can be formed in situ during additive manufacturing and with higher precision, therefore also [0093] a larger number of nozzles per surface area may be integrated, leading to a higher production rate per surface area [0094] the mechanical strength of the tip plate has increased and thus replacement of the bushing is only required after an extended service time [0095] a constant quality.