MXPA03011424A

MXPA03011424A - Anvil for friction stir welding high temperature materials.

Info

Publication number: MXPA03011424A
Application number: MXPA03011424A
Authority: MX
Inventors: D Sorensen Carl
Original assignee: Univ Brigham Young
Priority date: 2001-06-12
Filing date: 2002-06-12
Publication date: 2005-04-19
Also published as: JP2004528990A; EP1399286A4; CN1304160C; EP1399286A1; WO2002100586A1; CA2449972C; JP4322664B2; CN1516634A; CA2449972A1

Abstract

A friction stir welding anvil (14) and method of producing a friction stir welding anvil (14) that precludes diffusion or mechanical bonding of the anvil (14) to the work pieces (10A, 10B) are provided. The alternatives for producing such an anvil (14) comprise coating the anvil (14) with diffusion barriers such as oxides, nitrides, intermetallics, and/or refractory metals; manufacturing an anvil (14) either completely or partially from the same; or placing a coating (26) of such materials in the form of a thin sheet or a powder between the anvil (14) and the work pieces (10A, 10B). The anvil (14) disclosed herein exhibits high strength and hardness even at elevated temperatures, such as those greater than 800 °C, so as to prevent the anvil (14) from mechanically or diffusion bonding to the work pieces (10A, 10B) and so as to minimize, or eliminate altogether, anvil deformation.

Description

YUNQUE FOR HIGH TEMPERATURE MATERIALS OF ACTIVATION SOLVING BY RUBBING 1. Field of the Invention This invention relates to friction activation welding, and more particularly to an anvil used in friction activation welding processes which is coated with or made from a substance capable of resisting the deformation of the anvil and avoid bonding by diffusion or mechanical bonding between the anvil and the friction activation welding tool or the work piece when using high temperature welding materials for friction activation or work pieces. 2. Background and Related Technique The friction welding has been used for years in the welding industry. For example, when the ends of two tubes are pressed together, and simultaneously turned in opposite directions between them, heat is generated and causes the ends of the tubes to plasticize and bond. The rotation that quickly stops the tubes causes the two tubes to fuse together. Spray activation welding, on the other hand, is a relatively new technique, and was first described in U.S. Patent No. 5,460,317, filed October 24, 1995. Pneumatic activation welding involves pressing an activating welding tool. by rubbing not consumable with one end probed, profiled against two pieces of work at the point where they come in contact with each other. The cyclic movement of the probed end of the tool generates heat as it is pressed against the two work pieces. The probed end of the tool enters or pushes on the two workpieces in a plasticized region created by the friction of the probed end. The probed end can then move slowly to a region where the two pieces splice together, thereby allowing the area between the two pieces, which is under the probed end, to solidify together. There are a number of advantages for friction activation welding. These include the fact that during the friction activation welding, the heated material is not exposed to the combustion products. This reduces the chemical changes in the two work pieces due to the interconnection of the work pieces with the tool and its by-products. Another advantage of friction activation welding is that the temperature of the workpieces even in the heated region tends not to be as high as the temperature resulting from conventional welding processes. This reduced temperature reduces the oxidation of the workpieces due to the ambient atmosphere, thereby reducing the need to provide an inert atmosphere at the welding location. The friction activation solder has traditionally been limited to soldering of the low melting temperature material such as aluminum alloy, copper alloys, lead and magnesium alloys, due to wear at the probed end. These materials are effectively joined using standard steel base supports or anvils. However, recent advances in technology allow the activation welding by rubbing harder materials, previously unwelded. In order to join the so-called "high temperature materials", such as steels, stainless steels, nickel alloy or titanium alloys, it is necessary to use increased temperatures and forces. These increased temperatures and forces present new problems. For example, high temperature materials can lead to diffusion or mechanical bonding of the work pieces in the anvil. In addition, the activation welding by friction of high temperature workpieces can cause the unwanted and aggregate deformation of the anvil. The current trend in the art when joining high temperature materials is to avoid full penetration with the end plumbed to reduce the likelihood that diffusion of the mechanical bond of the work pieces will occur on the anvil. Unfortunately, if the probed end penetrates only a small amount into the joint, only a portion of the joint is heated and joined, and the weld is not as strong as when the weld is fully penetrated through the joint region. In addition, the material is not completely plasticized throughout the welded seam, causing a portion of the apparently welded region to be in the form of an overlap weld, which is a region where the material of one of the work pieces overlaps on , but does not completely link with, the material of the adjacent workpieces. The weakness of the weld is not always obvious or at least visible with the precursor inspection. Recent trends in the technique attempt to achieve full penetration welding. The number of inventions deal with adding a bevel or a notch for the anvil or the work pieces. (See US Patent Nos. 5,611,439 and 5,769,306). Additionally, a number of patents focus on using a feedback control system to control the depth of the rod, thereby controlling the level of penetration. (See US Patent Nos. 6,168,066 and 6,173,880). U.S. Patent No. 6,168,066 incorporates a ceramic sensor plate for detecting magnetic fields and currents to control the depth of the magnetic friction activation welding tool in milder non-magnetic materials. Accordingly, it may be an improvement in technique to increase or even replace current techniques with other techniques.

COMPENDIUM OF THE INVENTION Some embodiments of the present invention provide a friction activation welding anvil that forms a diffusion barrier between the work pieces and the anvil when friction activation welding is used. Some embodiments of the present invention provide an improved friction activation welding anvil that allows the welding of materials and workpieces normally considered 'rigid' and difficult to weld with conventional friction activation welding anvils. In addition, some embodiments of the present invention provide an improved friction activation welding anvil which allows complete penetration welding of materials currently difficult for frictional engagement welding with conventional friction activation welding anvils. Some embodiments of the present invention provide an improved friction activation welding anvil that resists the usual deformation attributable to the anvil when workpieces and materials of high friction activation welding temperature are used. Some embodiments of the present invention provide a friction activation welding anvil which prevents the diffusion bond between the work pieces and the anvil when friction activation welding is used. Also, some embodiments of the present invention provide a friction activation welding anvil that prevents mechanical bonding between the work pieces and the anvil when friction activation welding is used. Some embodiments of the present invention provide a friction activation welding anvil that is either coated with or made from at least one chemically inert material that allows a diffusion barrier to be formed between the work pieces and the workpiece. anvil In addition, some embodiments of the present invention provide a number of materials that can be used to coat an anvil or from which an anvil can be made to allow performance greater than that available with the current friction activation welding anvils. Additional features and advantages of the invention will become apparent to those skilled in the art from a consideration of the following detailed description taken in conjunction with the accompanying drawings. In a preferred embodiment, a system is provided by which a friction activation welding anvil is made from a chemically inert material such as an Oxide, Nitride, Carbide, or Silicate. In the embodiment, the anvil is generally a flat plate or rotating wheel that supports the work pieces while using friction activation welding. Alternatively, instead of the anvil which is comprised of the aforementioned materials, the chemically inert material is used to coat the anvil. The following are alternatives for the method of application or processing of the anvil using the aforementioned materials. In one embodiment, the anvil is created by directly spraying the metallic anvil with the chemically inert material. Alternatively, the anvil coated with the chemically inert material by chemical or vapor deposition. The anvil can also be coated with the chemically inert material through anodization or can be coated with the chemically inert material through sintering of ion beams. In addition, the anvil may be a complete insert comprised of the chemically inert material or the anvil may be coated with a powder form of the chemically inert material. In addition, the anvil can be coated with a powder form of the chemically inert material by suspension. Alternatively, the anvil can be coated with the chemically inert material by creating and bonding the chemically inert material simultaneously by reaction or transformation. In accordance with embodiments of the present invention, the geometry or shape of the anvil may vary to achieve more specific objectives, as long as the anvil is at least partially covered or is comprised of the chemically inert material. Additionally, any chemically inert coating that includes a metal combined with Oxygen, Nitrogen, Carbon or Silicon as a second or third component to respectively form an Oxide, a Nitride, a Carbide or a Silicate improves the performance of the anvil according to the embodiments of the present invention. In addition, any chemically inert coating that includes a chemically inert material, such as, but not limited to diamonds, improves anvil performance in accordance with embodiments of the present invention. The principles of the embodiments of the present invention allow complete penetration during welding of friction activation of traditionally conductive solder materials without friction, such as steel, titanium and other high temperature materials because the tool is not it sticks to the anvil or the work pieces and an improved welding is achieved. These and other features and advantages of the present invention will be established or become more fully apparent in the following description and the appended claims. The features and advantages can be realized and obtained by means of instruments and combinations particularly indicated in the appended claims. In addition, the features and advantages of the invention can be learned by practicing the invention or will become obvious from the description, as set forth in the following.

BRIEF DESCRIPTION OF THE DRAWINGS In order to obtain the form in which the characteristics previously observed and other advantages of the present invention, a more particular description of the invention will be made by reference to the specific modalities thereof, which are illustrated in the attached drawings. The understanding that the drawings represent only typical embodiments of the present invention and therefore, will not be considered as limiting the scope of the invention, the present invention will be described and explained with additional specificity and detail through the use and accompanying drawings. in which: Figure 1 is a cross-sectional view illustrating the face to be welded, wherein the illustration includes the line joining the work pieces and the supporting anvil; Figure 2 is another cross-sectional illustration of the face to be welded and showing the friction activation welding tool operating within the work pieces. Figure 3 represents a cross-sectional view of the face after welding with conventional anvils; Figure 4 represents a cross-sectional view of the face after welding with the embodiments of the present invention as described herein; Figure 5 illustrates a cross-sectional view representing the face to be welded and further represents a diffusion barrier coated on the anvil; and Figure 6 is yet another cross-sectional view illustrating the face to be welded and anvil which is comprised of an inert diffusion barrier.

DETAILED DESCRIPTION OF THE INVENTION Reference will now be made to the drawings in which various elements of the present invention will be given numerical designations in which the invention will be discussed to enable one skilled in the art to make and use the invention. It will be understood that the following description is only exemplary of the principles of the present invention, and should not be seen as narrowing the claims that follow. Some embodiments of the invention described herein provide full or partial penetration during the activation of friction activation of high temperature materials such as stainless steels. With the new advances in the tools used in devices and processes of friction activation welding, different materials with materials with higher fusion than those used in the past are now capable of successful friction activation solders. The high temperatures and pressures required to join high temperature materials or workpieces makes it necessary to have a diffusion barrier between the work pieces and the support to avoid the fusion bond between the work pieces and to avoid deformation of the anvil. Experimentation reveals that bonding by diffusion, mechanical bonding and deformation occurs between the workpieces and the anvil of conventional or standard steel when joining higher temperature materials of friction activation welding. In this way, the present embodiments written in the present avoid such anvil linkage to the work pieces during the friction activation welding process and decrease, if not altogether, the deformation of the anvil. In the specification and claims, the term "higher temperature materials" refers to those compositions or workpieces that are not easily welded by friction activation using traditional friction activating welding tools.These compositions are exemplified by, but not limited to steels, stainless steels, nickel alloys and titanium alloys When welding by friction activation the aforementioned materials, temperatures exceeding 1300 degrees centigrade and pressures exceeding 10 tons of force are typical. demonstrates a cross-sectional view through the face to be welded, showing two work pieces and an anvil 14 of support. The view shows the welding plates 10A and 10B which are joined together at the junction 12. Figure 2 shows a friction activation welding tool 22 and the welding plates 10A and 10B. The rod 16 frictionally laminates the material and welds the plate. When joining high temperature materials, the state of the art is to avoid the complete penetration that leaves a section not joined. Such lack of penetration, however, results in a weld having a cross section 24, as illustrated in Figure 3, where the bottom portion of the weld 18 is difficult with simple examination to determine whether or not it is welded and if it is not complete. Figure 4 shows a cross section 24 of a weld joining according to the principles of the embodiments of the present invention. A coated anvil 14 is illustrated which allows full penetration without the risk of diffusion or mechanical bonding of the workpieces in the anvil. The anvil can be coated, with an inert material that resists bonding by diffusion. In one embodiment, a flat rectangular anvil that is spray coated is used. Figure 5 shows a cross-sectional view of a coated anvil. The illustrated anvil includes a conventional steel core 28, which is sprayed with an inert coating 26 to resist diffusion bonding. According to the present invention, chemical vapor deposition is an alternative method for depositing materials on the conventional steel core. These materials include, for example, and not by way of limitation, carbides, nitrides, oxides and silicates. The inert coating shown in Figure 5 can be applied to the conventional steel core through, for example, a powder coating process. An inert powder is sprayed onto the existing steel anvil before placing the workpieces in a position ready for friction activation welding. When the work pieces move through the anvil, the powder coats the bottom of the work pieces and resists the bond. The coating in Figure 5 can alternatively be applied through anodization. Accordingly, the anvil is suspended in an electrolytic bath as an anode, and a current is passed through it. This process produces oxygen at the surface of the anode that reacts with the metal to form an oxide layer. Figure 6 illustrates an anvil that consists entirely of inert material 26. The modalities cover the use of the anvil as an insertion. An alternative embodiment for an anvil includes, but is not limited to, a cylinder or horizontal rotating roller. These and other geometries are intended to be included within the scope of the embodiments of the present invention. The proportion of an anvil that is coated with or includes inert chemicals is taught from traditional techniques due to the high cost of friction activation welding bits and economic pressures, which do not allow much attempt to complete penetration with high-grade materials. temperature. Although the lining typically can not prevent deformation of the anvil when the anvil is comprised of all types of materials, a liner typically prevents diffusion bonding in anvils constructed of most types of materials. In addition, prevention of bonding by diffusion and deformation occurs in anvils that are formed of materials that are highly resistant to heat deformation and that are coated in accordance with the teachings of the embodiments of the present invention. Subsequent welds in a deformed board or anvil typically cause severe problems with the surface location, however, the embodiments of the present invention include coated and uncoated solid anvil materials that maintain their elastic coefficients at elevated temperatures and will not be welded by diffusion (ie above 30 million psi for steel). Some of these materials are made of diffusion barrier materials discussed in the above. The modalities also include the use of marble and / or granite. The cooling of the anvil liquid or the table in which the work pieces are located regulate the heat flow, which can be used as a control parameter for the quality of the weld and maintain the coefficients of the board during the activation welding by rubbing. The solid ceramic materials may be used according to embodiments of the present invention to control heat flow based on their thermal conductivity. Solid ceramic materials can also be used as anvils and typically do not allow bonding by diffusion or deformation. Those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the teachings and advantages provided herein. Accordingly, all modifications are intended to be included within the scope of the embodiments of the present invention. Thus, as discussed herein, the embodiments of the present invention encompass friction activation welding and, more particularly, an anvil used in friction activation welding processes and, more particularly, an anvil used in process processes. friction activation welding that is either coated with or made from a substance capable of resisting anvil deformation and avoiding diffusion bonding or mechanical bonding between the anvil and the friction activation or welding tool Workpiece when materials or workpieces are used for high temperature welding by friction activation. The present invention can be represented in other specific forms without departing from its spirit or essential characteristics. The described modalities are also considered in all respects only as illustrative and not restrictive. The scope of the invention is therefore indicated by the appended claims rather than by the foregoing description. All changes that fall within the meaning and scope of equivalency of the claims will be encompassed within its scope.

Claims

CLAIMS 1. An anvil that is configured for use in friction activation welding, the anvil comprises: a core configured to support materials that are welded together by a friction activation welding process; and a chemically inert material that is included in one of: (i) the core; and (ii) a coating applied on at least a portion of the core. An anvil as set forth in claim 1, wherein the coating comprises one of: (i) an element selected from group IIIA of the periodic table of the elements; (ii) an element selected from the IVA group of the periodic table of the elements; (iii) an element selected from group IIIB of the periodic table of the elements; and (iv) an element selected from group IVB of the periodic table of the elements. An anvil as mentioned in claim 1, wherein the coating comprises one of. * (I) a diamond; (ii) an intermetallic; and (iii) a refractory metal. An anvil as set forth in claim 1, wherein the anvil forms a diffusion barrier between the materials that are welded together and an anvil surface when a friction activation welding process is performed. An anvil as set forth in claim 1, wherein the anvil allows full penetration to weld the materials. An anvil as set forth in claim 1, wherein the anvil resists deformation during the friction activation welding process. An anvil as set forth in claim 1, wherein the anvil avoids the mechanical bond between the materials and the anvil. An anvil as set forth in claim 1, wherein the chemically inert material comprises one of: (i) an oxide; (ii) a nitride; (iii) a carbide; and (iv) a silicate. An anvil as set forth in claim 1, wherein the core is one of: (i) a plate; and (ii) a rotating wheel. 10. A method for making a friction activation welding anvil which is capable of using high temperature friction activation welding materials, the method comprises the steps of: providing an anvil core that is configured to support materials that are welded together by a process of friction activation welding; and using a chemically inert material to provide one of: (i) the core of the anvil; and (ii) a coating on at least a portion of the core. A method as recited in claim 10, wherein the step for using a chemically inert material comprises one of the steps for: (i) using a spray coating process; (ii) use a deposition process; (iii) use an anodization process; (iv) use an ion beam sintering process (v) use a suspension process; and (vi) use a chemical reaction process. A method as recited in claim 10, wherein the step to use comprises the step to coat at least a portion of the core using a powder coating process, and wherein the chemically inert material is in powder form. . 13. A method as claimed in claim 10, wherein the chemically inert material comprises a metal and an oxygen. 14. A method as claimed in claim 10, wherein the chemically inert material comprises a metal and nitrogen. 15. A method as named in the claim 10, wherein the chemically inert material comprises a metal and carbon. 16. A method as claimed in claim 10, wherein the chemically inert material comprises a metal and silicon. 17. A method as set forth in claim 10, further comprising the step of forming the core into one of: (i) a flat plate; and (iii) a rotating wheel. 18. A method for providing an anvil for use in friction activation welding, the method comprising the steps for: providing an anvil having a core; place materials that will be soldered for activation by rubbing on the anvil; welding by activation by rubbing the materials; and monitor the temperature of the weld. 19. A method as named in the claim 18, wherein the step to provide includes the steps to: form a core cavity; and joining a conduit to the cavity. 20. A method as named in the claim 19, wherein the step for monitoring the temperature of the weld comprises the step for circulating a fluid through the cavity to regulate the temperature of the anvil.