HK1015426A - Textile fabric comprising bundles of machined metal filaments - Google Patents

Description

Fabric comprising a bundle of machined metal filaments

The invention relates to a fabric comprising a bundle of metal filaments obtained by cutting or skiving.

From us patent 4,930,199 a method is known for machining thin metal filaments by cutting, scraping or cutting off the end faces of thin metal sheets wound in a disc around a mandrel. This produces a nearly parallel bundle of filaments of predominantly quadrilateral cross-section. The equivalent cross-section is between 15 and 150 μm, depending on the thickness of the foil and the cutting speed of the cutting and scraping tool. Equivalent diameter refers to the diameter of a circle having an equivalent surface area to the quadrilateral cross-section of the filament.

Such machined filaments are typically drawn at a lower strength and are not straight as compared to drawn filaments. They are difficult to process at normal speeds into long filament yarns.

The object of the present invention is to provide a fabric comprising metal filaments or metal fiber bundles obtained by a cutting process, which are only lightly twisted together. The term "fabric" as used herein refers to a structure comprised of a mesh or openings and a bundle of filaments forming the boundaries of the mesh, such as a woven, knitted, knotted, interwoven or tufted structure.

Further, it is an object of the present invention to provide a method of processing a fabric with said filaments or bundles of fibres without twisting said elongate filaments or bundles of fibres. A considerable number of nearly parallel filament bundles are processed by cutting devices and therefore require additional densification or compaction for subsequent processing into fabrics by knitting, weaving, braiding, knotting or tufting.

Moreover, the initial bulk properties of the cutting bundles used in the fabric may need to be restored in later fabrics. The effect of this compaction and compaction process can be at least partially recovered. For certain applications, obtaining or maintaining a relative volume property in the fabric is a definite purpose, e.g. to obtain a certain flexibility of the fabric.

The invention also provides a fabric comprising a bundle of metallic filaments, wherein the filaments are cut and have an equivalent diameter of between 15 and 150 μm and are arranged approximately parallel in the bundle. The term "filament" as used herein refers to both continuous filaments and staple fibers.

The method of processing a fabric provided in accordance with the present invention comprises combining the cut filaments or bundles of filaments with an adhesive and processing the combined bundles of filaments or bundles into a fabric by, for example, weaving, knitting or braiding. If desired, this binder can be removed subsequently in succession in order to restore at least part of the initial bulk properties of the strands, by which is meant on the one hand a self-supporting filament-shaped or band-shaped object, for example, in a spiral around the filament or fiber strand, which can be wrapped up. On the other hand, glue that enables the bundle to be covered or wrapped. Depending on its composition, the binder can be eliminated, for example, by dissolving, melting, evaporating, freezing, oxidizing or burning, by pyrolysis, carbonization, or by other chemical reactions.

The invention also relates to the metal filaments or fibre bundles themselves obtained by the cutting process and can be combined with a binder and used, for example, in a method for processing textiles. The fabric according to the invention can be used in a wide range of applications, each being selected according to the composition, structure and characteristics of the metal filaments, in respect of the final structure of the binder and the fabric.

The metal filaments in the bundle can be copper, brass, titanium, different types of stainless steel, nickel alloys and other special steels, such as steels containing chromium, aluminum and/or nickel and 0.05 to 0.3% by weight of yttrium, cerium, lanthanum or titanium. This steel is very resistant to high temperatures (ferrochrome, nichrome, chromel alloy) and is therefore used, for example, in burner diaphragms, as will be explained below. If the sheet metal of the coil used for processing the filaments is coated with layers of different compositions on its surface, the cutting power is enhanced and the filaments are obtained as single or multicomponent filaments by the cutting process described above.

According to the above bundle, the binding filaments, as described above, the single or multiple filaments or yarns can be joined together under the binding filaments parallel to the metal bundles, if desired, in order to improve the performance of the finished fabric, in order to achieve the specific functions required for the non-uniform bundle, and thus and/or to obtain the final fabric. By incorporating other yarn structures in the fabric in addition to (and independently of) the merged bundle of metal filaments, it is also possible to process a non-uniform fabric. Regardless of the different types of application of the yarns and/or bundles of metal filaments, the fabric can present non-uniform characteristics, according to the limited area of the structuring which differs from one another throughout the thickness and/or the surface of the fabric. These substructures may differ from each other in terms of elasticity, compressibility, density, degree of hair, smoothness, toughness, etc. Such a structure can be connected by, for example, CMS 440 manufactured by Stoll corporation (Germany) or MC7 flat knitting machine manufactured by general-purpose corporation

Bundling is a material that can be used as warp and/or weft in all types of weaving processes. In circular knitting machines, flat knitting machines, and warp knitting machines, including raschel machines, they may be interwoven in mesh fabrics, tufted fabrics, or knitted warp, weft fabrics. The weight of the fabric can be between 300 and 4000g/m and is specified to be lower than 2500g/m². According to a preferred embodiment, the bundle is made of a metalA double layer flat knit structure or a circular knit structure can be incorporated to resist curling on the fabric edges.

The invention relates in particular to a fabric made of metal filaments or fibres, which is resistant to high temperatures and surprisingly effective for use in gas burners, i.e. surface radiation systems (100 kw/m)²Or higher) and blue flame systems (up to 10,000 kw/m)²) The membrane has a remarkable effect.

All this, as far as the knitted fabric can be used, is explained on the basis of several possible embodiments, for example for the burner membrane.

The filament bundle having a metric count (Nm) of between 0.2 and 0.4 is processed according to the cutting process described in us patent 4,930,199, wherein yttrium is present in the ferrochrome alloy in an amount of 0.1% by weight. The use of such alloy metal fibers obtained by known bundle drawing in burner diaphragms is well known, as in the european patent 0,390,255 application. The cut filaments have an equivalent diameter of between 25 and 50 μm, e.g. approximately 36 μm, and the bundles are connected to each other and drawn apart into a sliver at the draw frame. The slivers are then connected to one another again and, after a further drawing operation, are combined by winding in a so-called winding device to obtain a virtually parallel bundle of filaments, for example a continuous synthetic filament (e.g. binder) at a winding speed of 200 to 500 revolutions per minute. Before winding, a fiber core can be inserted between the slivers on the draft frame, if desired. The ratio of metals in the bundle is between 0.5 and 5, preferably between 1.5 and 5.

The bundle was processed on a flat knitting machine (gauge 5 to 7) to form a double-layer knit structure to better resist subsequent upward curling of the fabric edges. The fabric may have 800 to 2,000g/m²A weight of between, e.g., about 1,200g/m². Heavier fabrics have a longer life. The knitted fabric preferably has a thickness of approximately 2mm and a thickness of 800 to 1,500g/m²The weight of (c). The composition of the knitted structure is rather simple (e.g., 7 gauge interlock and circular jersey). The supporting threads of synthetic fibres may be incorporated during weavingTo facilitate the knitting process. The binder (and other non-metallic strands, if any) are removed by burning, leaving the fabric with a portion of its original volume of the chopped strands recovered. After the binder is removed, the fabric may also be rolled or uniformly compressed to obtain a fabric of uniform permeability.

These braids are then fixed to the premix gas burner frame as flat or cylindrical diaphragms in the flame plane. Gas burners as described in the WO P93/18342 application, etc. The furnace is fed with a usual propane/air mixture (with chemical mixing ratio and corresponding excess air). The long periods of time and duration of operation range from surface radiation systems to blue flame systems, including sudden interruptions in the period. The clear result is that the gas permeability of the fabric results in a uniform burning front of the gas at high flow rates, without flame flashback and squeaking. Thus, this is a good indicator of the temperature differentiation between the inlet side and the outlet side of the gas passing through the membrane. In summary, the emissions of CO and NOx remain low during operation. It may be recommended to use a punched or rolled diaphragm fabric if desired.

This woven structure has the following advantages compared to the conventional flexible sintered thin membrane. The problem of expansion of the rigid diaphragm sintered plate is avoided. In addition, the braid can provide a large surface in the form of an upward roll, so that the purpose of keeping the loss small can be achieved by cutting the braid. If a woven raschel fabric is used, the mesh will remain between 0.5 and 5 mm. In particular membrane surface areas, the mesh density can be made different from the adjacent surface areas in order to create different self-combustion systems within the membrane, depending on the gas flow rates used.

The braided structure also has the advantage of heating very quickly compared to sintered metal fiber burner membranes. Very strong heat pulses, such as pulses of less than one second, can be generated with the fabric of the present invention. This interesting feature of the fabric of the invention makes it possible to use it as a section of a burner for bending glass sheets. Such a furnace may comprise zones with different heat, as disclosed in european patent 0,659,697.

Within the framework of the invention it is also possible to use the woven Bekitherm fabric of the present application (e.g. knc1.knc3 type) as burner membrane. These fabrics are made of metal fibers (for example of ferrochromium) obtained by drawing bundles whose equivalent diameter is between 4 and 50 μm, as described in us patent 3,379,000. The parallel metal filament bundle is obtained after leaching treatment of the bundle components and can be spun into yarn. However, according to the method of the invention, the bundles can also be wound with binding filaments before weaving. If desired, two or more yarns or wrapped bundles may be twisted together for braiding or weaving to achieve a desired standard yarn denier. The yarn or wound bundle is made of drawn metal fibers in the form of a bundle, but may of course also be processed in a double layer structure on a flat knitting machine, as described above for bundles made of cut fibers. Other metallic starting materials than burner membranes can of course also be used in this way.

The fabric of the present invention can also be used in a filter card clothing to separate coarse particles from a hot gas stream. They can also act as thermal shields or shields when entering and exiting the tunnel oven.

The fabric can also be used to polish, for example, stainless steel surfaces. The cylindrical braid can be fitted over a bar or rod or tube, the outer surface of which is polished by a rubbing process.

When covered with a catalytic activator, the fabric can act as a support plate for the catalyst in the reactor. The fabric also acts as a support layer for the air bag filter.

Claims (15)

1. A fabric comprises a bundle of metallic filaments obtained by a cutting process, the equivalent diameter of which is between 15 and 150 μm, and the filaments in the bundle are arranged approximately in parallel.

2. A fabric according to claim 1, which is woven and has a weight of from 300 to 4,000g/m²In the meantime.

3. A fabric according to claim 1, which is pressed by rolling or by uniform pressing.

4. A fabric according to claim 2, having a double layer flat or circular knit construction.

5. Jersey fabric according to claim 4, characterized in that the equivalent filament diameter is between 25 and 50 μm and the ratio of metal in the bundles is between Nm0.5 and 5.

6. A fabric according to claim 5, having a weight of from 800 to 2,000g/m²In the meantime.

7. A fabric according to claim 1, comprising bundles of stainless steel filaments.

8. A fabric according to claim 1 which comprises bundles of titanium filaments.

9. A fabric according to claim 1, comprising filaments composed of an iron alloy containing chromium, aluminium and 0.05 to 0.3% by weight of yttrium.

10. A method of processing a fabric as claimed in claim 1, including processing the bundle into a fabric by combining and weaving, knitting or braiding the bundle of filaments with an adhesive.

11. A method according to claim 10, wherein the binder is removed in a subsequent process step.

12. The method of claim 10, wherein the metal fiber bundles are combined with a binder.

13. The bundle is wrapped with an adhesive and consists of nearly parallel metal filaments with an equivalent diameter between 25 and 50 μm and a ratio of metal in the bundle between nm0.5 and 5.

14. Use of a fabric according to claim 9 as a gas burner membrane.

15. Use of a fabric according to claim 6 wherein the filaments used as a gas burner membrane consist of an iron alloy containing chromium, aluminium and 0.05 to 0.3% by weight of yttrium.