Patent Publication Number: US-2012024465-A1

Title: Systems and methods for stator bar press tooling

Description:
RELATED APPLICATIONS 
     This application is related to application Ser. No. ______, filed concurrently with the present application on ______, entitled: “Systems and Methods for Stator Bar Shape Tooling,” the content of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention generally relates to tooling, and in particular, to stator bar press tooling. 
     BACKGROUND OF THE INVENTION 
     A stator is a stationary part of an electric machine, such as a generator or motor. In a generator, current can be induced in the stator coils by the influence of the rotor&#39;s rotating field coils. A stator coil in a small electric machine can be made from wire coils that are wrapped in an arrangement to form a cylindrical frame for surrounding the rotor. The wire is usually coated with an insulating lacquer so that adjacent coil windings do not short circuit with one another. In large industrial generators, however, the stator winding must carry a large amount of current, and are therefore, usually made from elongated bars of copper, for example. The stator bars are bent or formed into specific, complex shapes, and multiple pairs of approximately mirror-imaged stator bars usually are arranged in a cylindrical array and electrically connected to create loops for which the rotor field coil can induce currents. One of the challenges in building or refurbishing an electrical generator is the bending or forming of the stator bars into the correct shape so that the array can be assembled quickly, and so that the correct spacing tolerance is maintained between each of the stator bars. 
     Stator bars can be subject to high voltage potentials during the operation of the electric machine, and may arc under certain conditions. Arcing is a particular problem in certain sections of the stator bar, particularly where the stator bar is bent and where high electric field strengths are present. Insulation material can be utilized to wrap or coat the stator bars to allow the stator to be run at higher potentials without arcing. However, small gaps, bubbles, and/or imperfections in the insulation can reduce the effective dielectric constant of the insulation and lead to arcing, damage, and failure of the stator bar and electrical machinery. 
     BRIEF SUMMARY OF THE INVENTION 
     Some or all of the above needs may be addressed by certain embodiments of the invention. Certain embodiments of the invention may include systems and methods for providing stator bar press tooling. 
     According to an example embodiment of the invention, a method is provided for pressing and curing insulation material on a shaped element. The method can include providing tooling. The tooling can include an inner press and an outer press, wherein at least an inner press surface associated with the inner press and an outer press surface associated with the outer press are fabricated at least in part by sintering. The method can include applying at least one of pressure or heat to insulation material in contact with a shaped element with the tooling, wherein the inner press surface and the outer press surface of the tooling conform to least an external portion of the shaped element. 
     According to another example embodiment, a system is provided for pressing and curing insulation material on a shaped element. The system can include an inner press and an outer press, wherein at least an inner press surface associated with the inner press, and an outer press surface associated with the outer press, are fabricated at least in part by sintering. 
     According to another example embodiment, a method is provided for manufacturing press tooling. The method includes fabricating an inner press and an outer press, wherein fabricating at least an inner press surface associated with the inner press, and an outer press surface associated with the outer press, is facilitated at least in part by sintering. 
     Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. Other embodiments and aspects can be understood with reference to the following detailed description, accompanying drawings, and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Reference will now be made to the accompanying tables and drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  is a pictorial diagram of illustrative shape tooling according to an example embodiment of the invention. 
         FIG. 2  is a pictorial diagram of illustrative press tooling according to an example embodiment of the invention. 
         FIG. 3  is a flow diagram of an example method according to an example embodiment of the invention. 
         FIG. 4  is a flow diagram of another example method according to an example embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. 
     Certain embodiments of the inventions may enable tooling to be made for pressing, heating, and/or curing materials such as coatings or insulation. According to certain example embodiments, the tooling may include pressing surfaces having shapes designed and manufactured using rapid prototyping methods, including laser sintering based on three-dimensional computer modeling. In certain example embodiments of the invention, custom pressing surfaces may be produced with accuracy, repeatability, and speed. In certain example embodiments, the pressing surfaces may provide a surface for pressing, heating, and/or curing insulation material (for example, mica tape) surrounding a stator bar. In certain example embodiments of the invention, the press surface may include complex curvature that corresponds to the curvature of the stator bar so that uniform pressure can be applied to the coatings or insulation. 
     According to example embodiments of the inventions, various tooling for shaping an element or for pressing an insulating material onto a shaped element will now be described with reference to the accompanying figures. 
       FIG. 1  illustrates an example pictorial diagram of shape tooling  100  according to an example embodiment of the invention. The shape tooling  100  may be utilized for shaping an element  102  (such as stock material) into a formed element  104  such as a stator bar. According to an example embodiment, the element  102  may be a metal such as copper, nickel, steel, or a metallic alloy. According to an example embodiment, the shape tooling  100  may include one or more curved sections  108 ,  109  to facilitate the bending or shaping of the element  102 . In an example embodiment, the shape tooling  100  may include a first curved section  108  having a first constraining surface  106 . In an example embodiment, the shape tooling  100  may include a second curved section  109  having a second constraining surface  116 . According to an embodiment of the invention, a shaping hammer  110  made of rubber, wood, metal or other suitable material may be utilized to shape, deform, or define the element  102  to have one or more curved element sections  112 ,  114  corresponding to the shape of the constraining surfaces  106 ,  116 . In an example embodiment, the element  102  may be deformed with at least one constraining surface  106 ,  116  to define at least an external shape of a formed element  104 . 
     In certain example embodiments, at least the constraining surfaces  106 ,  116  of the curved sections  108 ,  109  may be fabricated using rapid prototyping techniques such as selective laser sintering. For example, selective laser sintering may include fusing together a material by laser scanning cross-sections of powdered material (metal powder and/or a polymer binder) in a pattern generated from a three dimensional digital representation of the at least one constraining surface  106 ,  116 . In certain example embodiments, some or all of the curved sections  108 ,  109  may be fabricated using rapid prototyping techniques. According to example embodiments of the invention, elements  102  may be shaped with at least a curved element section  112 ,  114  corresponding to at least a portion of the at least one constraining surface  106 ,  116 . The constraining surface  106 ,  116  may correspond to a pattern generated, for example, from a three dimensional digital representation of the at least one constraining surface  106 ,  116 . 
     According to an example embodiment, the element  102  may be shaped or formed with at least a first curved element section  112  and a second curved element section  114 . The first curved element section  112  may correspond to at least a portion of the at least one constraining surface  106 , and the second curved element section  114  may correspond to at least a portion of a second constraining surface  116 . In an example embodiment of the invention, a first constraining surface  106  and a second constraining surface  116  correspond to respective patterns generated from, for instance, three-dimensional digital representations of the first constraining surface  106  and the second constraining surface  116 . 
     According to example embodiments of the invention, the tooling curved sections  108 ,  109  and constraining surfaces  106 ,  116  are operable for shaping an element  102  into a formed element  104  associated with a generator. The formed element  104  may include at least one of a stator bar, a stator coil, a buss bar, or a connection ring. In certain example embodiments, the element is made of copper  102 . In an example embodiment, at least the constraining surface  106 ,  116  or the curved section  108 ,  109  of the tooling are operable for mounting to a tooling frame. According to an example embodiment, the constraining surface  106 ,  116  is operable to retain its shape while forcing and deforming the element  102  against the tooling. 
       FIG. 2  is a pictorial diagram of illustrative press tooling  200  according to an example embodiment of the invention. According to an example embodiment of the invention, the press tooling  200  may include an inner press  204  and an outer press  206 . In an example embodiment, the inner press may include an associated inner press surface  205  having a curvature that corresponds to the curvature of a shaped element  202 . Likewise, the outer press  206  may include an outer press surface  207  having a curvature that corresponds to the curvature of the shaped element  202 . In an example embodiment of the invention, the shaped element  202  may be a stator bar, a stator coil, a buss bar, or a connection ring. 
     In an example embodiment of the invention, the shaped element  202  may be covered or wrapped in an insulating material  208  such as mica tape. In an example embodiment, the insulating material  208  may include additional materials such as polyester, a glass backing for strength, mica for dielectric resistance, and epoxy or heat activated adhesive, that when heated, may flow between and around the insulating material  208  and the shaped element  202 . In certain example embodiments, the inner press  204  and outer press  206  may be utilized to apply pressure to the insulting material  208  surrounding the shaped element  212 . In certain example embodiments, the inner press  204  and/or the outer press  206  may include one or more heaters  216  in thermal communication with the press surfaces  205 ,  207  for heating and/or curing the insulation material  208  while applying pressure to the insulting material  208  and shaped element  212 . 
     According to an example embodiment, the inner press  204  and/or the outer press  206  may include an optional press lip  210  to constrain one or more edges of the shaped element  202  while aligning, pressing and/or heating the insulating material  208  against the shaped element  202 . In certain example embodiments of the invention, a press actuator  214  may be in contact with the outer press  206  and/or the inner press  204 , and may be utilized to apply pressure to the insulating material  208 . In an example embodiment, the insulating material may be pressed by pressing the shaped element  212  between the inner press  204  and the outer press  206 . In other example embodiments, one of the outer press  206  or the inner press  204  may be attached to a stationary frame while the other press is connected to the press actuator  211  so that only one press actuator is used. 
     According to example embodiments of the invention, at least an inner press surface  205  associated with the inner press  204  and an outer press surface  207  associated with the outer press  206  are fabricated at least in part by sintering. For example, selective laser sintering may include fusing together a material by laser scanning cross-sections of powdered material (metal powder and/or a polymer binder) in a pattern generated from a three dimensional digital representation of at least a portion of the press  204 ,  206  and/or press surface  205 ,  207 . 
     Certain embodiments of the invention include tooling for applying at least one of pressure or heat to insulation material  208  in contact with a shaped element  202 . For example, the inner press surface  205  and the outer press surface  207  of the tooling  204 ,  206  may conform to least an external portion of the shaped element  202 . According to example embodiments, the shaped element  202  may be associated with a generator and may include at least one of a stator bar, a stator coil, a buss bar, or a connection ring. In example embodiments, the inner press  204  and the outer press  206  may include at least a curved surface. 
     An example method  300  for shaping an element will now be described with reference to the flowchart of  FIG. 3 . The method  300  starts in block  302  and may include providing at least one constraining surface, where the at least one constraining surface is fabricated at least in part by selective laser sintering. In block  304 , the method  300  includes deforming an element with the at least one constraining surface to define at least an external shape of a formed element. The method  300  ends after block  304 . 
     An example method  400  for pressing and curing insulation material on a shaped element will now be described with reference to the flowchart of  FIG. 4 . The method  400  starts in block  402  and may include providing tooling including an inner press and an outer press, wherein at least an inner press surface associated with the inner press, and an outer press surface associated with the outer press, are fabricated at least in part by sintering. In block  404 , the method  400  includes applying at least one of pressure or heat to insulation material in contact with a shaped element with the tooling, wherein the inner press surface and the outer press surface of the tooling conform to least an external portion of the shaped element. The method  400  ends after block  404 . 
     Accordingly, example embodiments of the invention can provide the technical effects of creating certain systems and methods that provide rapid production of tools for pressing elements. Example embodiments of the invention can provide the further technical effects of providing systems and methods for providing accurate constraining and/or heating surfaces for pressing and curing insulation material on shaped elements, such mica tape on stator bars. 
     In example embodiments of the invention, the shape tooling  100  and the press tooling  200  may include additional hardware that can enable the manufacturing and use of the tooling. As desired, embodiments of the shape tooling  100  and the press tooling  200  may include more or less of the components illustrated in  FIGS. 1 and 2 . 
     The invention is described above with reference to block and flow diagrams of systems and methods, according to example embodiments of the invention. It will be understood that some blocks of the block diagrams and flow diagrams may not necessarily need to be performed in the order presented, or may not necessarily need to be performed at all, according to some embodiments of the invention. 
     While the invention has been described in connection with what is presently considered to be the most practical and various embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. 
     This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined in the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.