| Method for providing turbulation on the inner surface of holes in an article, and related articles -> Monitor Keywords |
|
|
 
Method for providing turbulation on the inner surface of holes in an article, and related articlesRelated Patent Categories: Metal Fusion Bonding, ProcessMethod for providing turbulation on the inner surface of holes in an article, and related articles description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060138195, Method for providing turbulation on the inner surface of holes in an article, and related articles. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] In a broad sense, this invention relates to methods for enhancing cooling efficiency in high temperature components. In some of the more specific embodiments, the invention is directed to providing roughness on the internal surfaces of cooling holes within turbine engine components. [0002] A number of techniques are currently available for maintaining the temperature of turbine engine components below critical levels. As an example, coolant air from the engine compressor is often directed through the component, along one or more component surfaces. Moreover, relatively long radial cooling holes are often drilled through turbine blades, to serve as conduits for coolant air. [0003] The radial cooling holes are often formed by a process known as Shaped Tube Electrolytic Machining, or "STEM drilling". The STEM process is an electrochemical machining technique which is especially useful for drilling small holes with large depth-to-diameter ratios. A very important advantage of this process is that it can be used to provide roughness to the inner surface of the cooling holes. The roughness greatly enhances heat transfer through the holes. STEM drilling is mentioned in various references, such as U.S. Pat. Nos. 5,927,946 and 5,820,744. [0004] In brief, STEM systems often utilize one or more negatively-charged titanium tubes, an acid electrolyte, and a positively-charged substrate or work-piece. The electrolyte is pumped into the substrate, dissolving the metal in the pre-selected path of the cooling hole. In order to produce roughness within the holes, the injection of the electrolyte is intermittently stopped as the depth of the hole is being increased. This intermittent action results in the formation of protrusions along the length of the cooling holes. The protrusions provide the roughness and surface area required for the enhanced heat transfer. [0005] While STEM drilling is a useful technique in many instances, it has some disadvantages also. For example, the process is very slow. Thus, when a significant number of holes have to be drilled, the considerable time required can result in high processing cost. The equipment required can also be quite expensive. Moreover, STEM drilling can produce etching debris which can decrease heat transfer efficiency in the hole, if not removed properly. Furthermore, STEM drilling sometimes results in inconsistent roughness patterns on the passage hole surface, which also can adversely affect heat transfer efficiency. [0006] Thus, new methods for providing turbulation to the surface of passage holes in an article would be welcome in the art. The methods should be capable of securing the turbulation to any selected area of the hole wall. Moreover, the methods should allow one to change the shape, size, and pattern of the desired turbulation, as well as its composition. The methods should also be compatible with any other processes being used in conjunction with the article, and should not add excessive costs to the fabrication thereof. SUMMARY OF THE INVENTION [0007] One embodiment of the present invention calls for a method of providing turbulation on the inner surface of at least one passage hole. The passage hole can be located in a variety of different articles. One important example is a pattern of cooling holes for some portion of a turbine engine component, e.g., radial cooling holes which extend through a turbine blade. (As used herein the term "hole" is meant to embrace a variety of internal regions or cavities in an article, including indentations and hollow regions.). The turbine engine component is usually formed of a nickel- or cobalt-based superalloy material. [0008] The turbulation is first applied to a substrate which can eventually be inserted into the passage hole. In many embodiments, the substrate, or "mandrel", is a bar or rod, formed of a sacrificial material, as described below. (The bar can be solid or hollow, and in the latter instance, is sometimes referred to as a "tube"). Turbulation material, often comprising a nickel- or cobalt-based metal alloy, can be applied to the substrate in various forms. For example, it can be applied freely as a powder, or as part of a slurry, metal foil, or tape (e.g., a green braze tape). [0009] After the turbulation is applied to the substrate, the substrate can be inserted into the passage hole. The substrate is inserted to an extent sufficient to position the turbulation adjacent to a selected area of the inner surface of the hole. The turbulation material is then fused to the inner surface, using a number of heating techniques described below. The sacrificial substrate can then be removed from the hole by various techniques. [0010] Other methods for applying turbulation to the substrate also constitute part of this invention. For example, the surface of the substrate can be provided with indentations which have dimensions corresponding to the turbulation desired for the passage hole. The indentations are filled with a bonding agent-turbulation composition, and the substrate is then inserted into the passage hole. Following the fusing step and the elimination of the substrate, the turbulation remains attached to the hole surface, via the bonding agent. [0011] As another alternative, a relatively thin substrate (usually a bar or rod) can be used as the support for a number of rings. The rings encircle the bar, and are each formed of a bonding agent-turbulation composition. Rings formed of a sacrificial material can be alternated with the bonding agent-turbulation rings, along the length of the substrate. After insertion of the substrate-ring assembly into the passage hole, the substrate can be withdrawn, and the turbulation-containing rings can be fused to the wall of the hole. The sacrificial rings can be removed from the passage hole, as described below. [0012] As another alternative, the substrate itself can be a metal foil, formed of the bonding agent material. Turbulation can be applied to the foil, and the foil can be cut to a size sufficient for fitting into the passage hole. The foil can then be rolled into a tube, with the turbulation disposed on its inner surface. The tube is then inserted into the passage hole, and fused thereto, so that the turbulation is bonded to the wall of the hole. [0013] Yet another embodiment is directed to an article, comprising: [0014] (I) a substrate containing at least one passage hole, wherein the passage hole includes an inner surface; and [0015] (II) turbulation material bonded to the inner surface of the passage hole by a bonding agent. As described herein, the article is often a turbine engine component, containing a number of radial cooling holes which include the turbulation. [0016] Further details regarding the various features of this invention are found in the remainder of the specification. BRIEF DESCRIPTION OF THE DRAWINGS [0017] FIG. 1 is an illustration of a cylindrical, metal mandrel on which turbulation has been applied. [0018] FIG. 2 is a cross-sectional view (end-view) of the cylindrical mandrel of FIG. 1, after application of a bonding agent. [0019] FIG. 3 is a side-elevational view of an indented cylindrical mandrel. [0020] FIG. 4 is a right side-view of the mandrel of FIG. 3. [0021] FIG. 5 is an illustration of the mandrel of FIG. 3, after the indentations have been filled with a metal-binder material. [0022] FIG. 6 is an illustration of the mandrel of FIG. 5, while being inserted into a passage hole. [0023] FIG. 7 illustrates the passage hole of FIG. 6, after removal of the mandrel. Continue reading about Method for providing turbulation on the inner surface of holes in an article, and related articles... Full patent description for Method for providing turbulation on the inner surface of holes in an article, and related articles Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method for providing turbulation on the inner surface of holes in an article, and related articles patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Method for providing turbulation on the inner surface of holes in an article, and related articles or other areas of interest. ### Previous Patent Application: Method for producing connecting ends on metal hoses and hose piece comprising such connecting ends Next Patent Application: Friction stirring-welding method Industry Class: Metal fusion bonding ### FreshPatents.com Support Thank you for viewing the Method for providing turbulation on the inner surface of holes in an article, and related articles patent info. IP-related news and info Results in 0.7726 seconds Other interesting Feshpatents.com categories: Software: Finance , AI , Databases , Development , Document , Navigation , Error 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
