Abstract:
A plurality of substantially identical, thermally and/or atmospherically isolated modules can be employed to effect a treatment process. Each module can include a thermal system and/or atmospheric control system to effect a step of a treatment process, such as a heat treatment process for metal articles, particularly heat treatment and/or welding of parts made from so-called “super allows.” The module control systems can communicate and/or cooperate to carry out a process.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of currently pending U.S. patent application Ser. No. 13/561,778 filed on Jul. 30, 2012. The application identified above is incorporated herein by reference in its entirety for all that it contains in order to provide continuity of disclosure. 
    
    
     BACKGROUND OF THE INVENTION 
     The disclosure relates generally to welding furnaces, and more particularly to welding furnaces allowing special handling of work pieces made from superalloys. 
     Components of apparatus that are exposed to high temperatures and/or high stress environments, such as rotor blades in a gas turbine engine, for example, are generally made of high performance alloys. In particular, so-called “superalloys” have come into wide use for such applications. These superalloys typically are based on nickel and/or cobalt and are generally used to form articles by casting. However, circumstances arise in which components must be welded. For example, because superalloys are expensive, it has become desirable to repair or restore parts made from superalloys rather than outright replace such parts. While articles of relatively simple geometries may be welded in currently-available welding apparatus with success, articles of more complex geometries may not enjoy as successful or high quality welding in such apparatus, particularly where such articles are processed at elevated temperatures. In addition, superalloy parts tend to oxidize in ambient atmosphere at such elevated temperatures, which contributes to failure or poor quality of welds. 
     Some superalloy components require thermal stress relief prior to welding so that residual stresses in the components may be removed or relieved. For example, if a component has been removed from service in a gas turbine, such as for reconditioning or repair, stresses may remain in the component as a result of its service. Welding and/or cooling after welding may also induce stresses in components requiring additional stress relief, such as with heat treatment. As is known, heat treatment follows specific processes including ramping rates, soak temperatures, hold times, and cooling rates that improve the likelihood of achieving desired qualities in the final article or component. Deviation from these processes may result in flaws or undesired characteristics of the final article or component. As a result, it is recognized that a high degree of control over the environment in which an article is processed is desirable. 
     Heat treatment of articles in the past generally employed large-scale blast furnaces and the like in which large numbers of articles were treated at the same time. However, such large-scale solutions typically have long heat treatment times due to several factors. For example, a large blast furnace as a large mass to heat, and the typically large number of parts being heat treated in a batch adds additional mass. Additionally, long queuing times may occur while batches are assembled as individual components are repaired. Therefore, batch furnace pre-weld and post-weld stress relief heat treatments may cause delay in a welding line. Further, such large—scale blast furnaces typically have no control over the atmospheric composition to which the parts are exposed, thus exposing superalloy parts to potentially oxidizing ambient atmosphere. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Embodiments of the invention disclosed herein may take the form of a welding apparatus having a first enclosure arranged to receive an article to be processed and a heating system arranged to heat the article to be processed in the first enclosure. A first enclosure door into the first enclosure may be arranged to selectively allow access to the first enclosure through a first side of the first enclosure, and an atmosphere control system may be arranged to provide a substantially inert atmosphere in at least the first enclosure. The atmosphere control system may include a sealing system arranged to retain a desired atmosphere in each enclosure under control of the atmosphere control system. A viewport assembly may be arranged on a second side of the first enclosure and may include a window made of a high-temperature-resistant, substantially transparent material arranged to allow viewing of the first enclosure from outside the first enclosure. 
     Another embodiment may include a viewport assembly for a welding apparatus having a neck extending from an attachment end to a viewing end. The attachment end may include an attachment arrangement arranged to attach the viewport assembly to a welding apparatus, and the neck may form a passage from the attachment end to the viewing end. The neck may have an end wall of the neck at the viewing end and a window made from a high-temperature-resistant, substantially transparent material may be mounted in the end wall. 
     Another embodiment may take the form of a modular heat treatment system comprising a retort chamber arranged to receive an article to be welded and a retort chamber heating system arranged to heat the retort chamber to a first predefined temperature. A retort portion of an article transport arrangement may extend into the retort chamber from a first side of the retort chamber. A retort door at the first side of the retort chamber may selectively provide access to the interior of the retort chamber through the first side. A first thermal chamber may be attached to the first side of the retort chamber and may include a first portion of the article transport arrangement arranged to be connected to the retort portion of the article transport arrangement to allow transport of an article from the first thermal chamber into the retort chamber. The first thermal chamber may also include a first thermal system arranged to place an interior of the first thermal chamber at a second predefined temperature, the first thermal system being at least one of a heating system and a cooling system. A first chamber door may be provided in a side of the first thermal chamber other than a side at which the first thermal chamber is attached to the retort chamber to selectively allow access to an interior of the first thermal chamber. 
     Other aspects of the invention provide methods, systems, program products, and methods of using and generating each, which include and/or implement some or all of the actions described herein. The illustrative aspects of the invention are designed to solve one or more of the problems herein described and/or one or more other problems not discussed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       These and other features of the disclosure will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various aspects of the invention. 
         FIG. 1  shows a schematic diagram of a welding apparatus according to embodiments of the invention disclosed herein viewed from a side. 
         FIG. 2  shows a schematic diagram of a viewport of a welding apparatus according to embodiments of the invention disclosed herein viewed from an end. 
         FIG. 3  shows a schematic diagram of a welding apparatus according to embodiments of the invention disclosed herein. 
     
    
    
     It is noted that the drawings may not be to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings. 
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     As indicated above, aspects of the invention provide a welding apparatus and method. With reference to  FIGS. 1 and 2 , embodiments of the invention disclosed herein may include a welding apparatus  100  including a first enclosure  102  arranged to receive an article to be processed  104 . A heating system  106  may be arranged in first enclosure  102  to heat the article to be processed  104 . For example, heating system  106  may include a plurality of radiant heating elements, though other heat sources may be employed in embodiments. A first enclosure door  108  may selectively allow access to first enclosure  102  through a first side  110  of first enclosure  102 . An actuator  112  may be included to open and close first enclosure door  108  as may be desired. Any suitable actuator and door may be used, though embodiments may employ a guillotine-style door of a material that may withstand extreme heat, such as a ceramic material. A suitable material should be selected to withstand temperatures required for processing the article  104 , such as at least 1800 degrees Fahrenheit where an article to be processed is made from a superalloy. 
     In embodiments, an atmosphere control system  114  may be configured to provide a substantially inert atmosphere in first enclosure  102 . For example, atmospheric control system  114  may supply argon, hydrogen, nitrogen, or another gas that will have little or no chemical interaction with the article to be processed  104 . Atmospheric control system  114  may additionally induce a positive pressure in first enclosure  102  so as to prevent entry of ambient air into first enclosure  102  from the exterior of first enclosure  102 . A sealing system  116  may be arranged to retain atmosphere in first enclosure  102  and/or to prevent entry of external atmosphere into first enclosure  102 . Sealing system  116  may include, for example, gaskets, toothed seals, labyrinth seals, or other seals as may be appropriate. 
     A viewport assembly  118  on a second side  120  of first enclosure  102  may allow a user to view the interior of first enclosure  102 . A window  122  made of a high-temperature-resistant, substantially transparent material may be mounted in viewport assembly  118 . For example, window  122  may be made from sapphire, which may remain transparent and withstand temperatures of 1800 degrees Fahrenheit without significant damage, though other materials might be employed as suitable and/or desired. Window  122  may be mounted in an end wall  124  of a neck  126  of viewport assembly  118  attached to second side  120  of first enclosure  102  via an attachment point  128 . A viewport door  130  may be provided at the attachment arrangement end of neck  126  and may selectively be closed to reduce or eliminate heat from entering neck  126  and/or to strike window  122 , such as with a viewport door actuator  132 . In addition, at least one access port  134  may be included in viewport assembly  118 , such as in end wall  124 . Access port  134  may be used, for example, to allow a user selective access to first enclosure  102 , such as to use a welding device  103  to weld the article to be processed  104 . Attachment point  128 , access port  134 , window  122 , and/or other portions of viewport assembly  118  may include seals compatible with sealing system  116  of first enclosure  102  so as to preserve atmospheric integrity within first enclosure  102  and in viewport assembly  118  as controlled by atmosphere control system  114 . 
     In another embodiment of the invention disclosed herein, as seen in  FIG. 3 , a modular heat treatment system  300  may include a retort chamber  302  arranged to receive an article to be welded  304 . A retort chamber heating system  306  may be arranged to heat retort chamber  302  to a first predefined temperature, and a retort portion  308  of an article transport arrangement  310  may extend into retort chamber  302  from a first side  312  of retort chamber  302 . A retort door  314  at first side  312  of retort chamber  302  may selectively provide access to the interior of retort chamber  302  through first side  312 , such as by being opened and closed by an actuator  316 . An atmospheric control system  318  may maintain an atmosphere within retort chamber  302 , such as by maintaining an atmosphere of a gas that is substantially inert with respect to the article to be processed. For example, argon, hydrogen, nitrogen, or another gas that is substantially non-reactive with superalloys used in turbine blades may be used. 
     A first thermal chamber  320  attached to first side  312  of retort chamber  302  may include a first portion  322  of article transport arrangement  310  and may be arranged to be connected to retort portion  308  of article transport arrangement  310  to allow transport of an article from first thermal chamber  320  into retort chamber  302  and vice versa. First thermal chamber  320  may include a first thermal system  324  arranged to place an interior of first thermal chamber  320  at a second predefined temperature. In embodiments, first thermal system  324  may be a heating system, while in other embodiments, first thermal system  324  may be a cooling system, depending on the particular processes sought to be performed with modular heat treatment system  300 . First thermal chamber  320  may further include a first chamber door  326  in a side  328  of first thermal chamber  320  other than a side  330  at which first thermal chamber  320  is attached to retort chamber  302 . Like retort door  314 , first chamber door  326  may selectively allow access to an interior of first thermal chamber  302 , such as by being opened and closed with actuator  332 . Both retort door  314  and first chamber door  326  may be made from heat-resistant materials selected to withstand and/or insulate against temperatures retort  302  and/or first thermal chamber  320  may experience. First thermal chamber  320  may additionally include an atmospheric control system  334  arranged to maintain a desired atmosphere within first thermal chamber  320  and/or retort chamber  302 , like atmospheric control system  318  of retort chamber  320 . Atmospheric control systems  318 ,  334  may coordinate in embodiments, or may operate independently, or one may become a portion of the other as suitable and/or desired. 
     In embodiments, a second thermal chamber  338  may be attached to retort chamber  302  or first thermal chamber  320 . Second thermal chamber  338  may be substantially structurally identical to first thermal chamber  320  and/or retort chamber  302 , and may include a second thermal system  340 , a respective portion  342  of article transport arrangement  310 , and/or a respective atmospheric control system  344  that may coordinate with and/or become part of retort atmospheric control system  318  and/or first thermal chamber atmospheric control system  334  to maintain a substantially inert atmosphere in retort  302 , first thermal chamber  320 , and/or second thermal chamber  338 . Second thermal chamber  338  may also include a second chamber door  346  operated by an actuator  348  to provide access between second thermal chamber  338  and retort chamber  302 . Where second thermal chamber  338  is the last thermal chamber, it may also include an end door  350  operated by a respective actuator  352 . 
     By providing such substantially structurally identical thermal chambers, a heat treatment system may be assembled that may perform any heat treatment cycle desired. For example, in the example shown, first thermal chamber  320  may be a pre-heat chamber in which an article may be heated to a first temperature for a first period in preparation for entry into retort chamber  302 , and second thermal chamber  338  may be a cooling chamber. Additional chambers could be connected to either end of the assembly to accommodate whatever additional steps might be performed, each chamber including a suitable heating or cooling system as its thermal system. 
     A viewport assembly  354  may be attached to a second side  348  of retort chamber  302  and arranged to allow viewing of an interior of retort chamber  302  from an exterior of retort chamber  302 . Viewport assembly  354  may, for example, be provided as described with respect to  FIGS. 1 and 2  above. Additional such viewport assemblies may be attached to any of first or second thermal chamber  320 ,  338 , and/or any additional thermal chambers of modular heat treatment system  300  as may be provided. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.