Patent Publication Number: US-10767241-B2

Title: Support fixture for heat treating sheets having complex shapes

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit, in accordance with 35 U.S.C. § 119(e), of U.S. Provisional Patent Application Ser. No. 62/264,615; filed on Dec. 8, 2015, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention is directed to support fixtures for holding sheets having complex three dimensional shapes during heat treatment of the sheets, and more particularly for fixtures having flow channels for facilitating uniform and accelerated heating and cooling of the sheets and mitigating thermally induced distortion of the sheets. 
     BACKGROUND 
     Sheets having a complex shape have numerous uses in many fields. For example, turbines (such as those of, e.g., a jet engine) generally employ one or more such sheets for various purposes, e.g., to generate thrust. It is required of sheets having a complex shape that the sheets be manufactured precisely, accurately, and with uniformity, at least in order to ensure predictability in the sheet&#39;s application. However, due to practical aspects intrinsic in manufacturing processes of the prior art, it is difficult to manufacture sheets having complex shapes with the requisite precision, accuracy, and uniformity. 
     In addition, such sheets are typically heat treated and quenched to impart predetermined properties. However, sheets having the complex shapes tend to warp and distort during heating and quenching. Some fixtures used to hold the sheets during heat treatment and quenching do not eliminate the warping and distortion and can worsen it. 
     There is an unfulfilled need for fixtures for holding sheets having complex shapes during heat treating. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present invention is directed to a fixture for holding sheets having complex shapes during heat treating, the fixture comprising: a base having at least one central opening extending there through, the base defining a peripheral foundation; a support structure extending inwardly and upwardly from the base and across the central opening, the support structure having a plurality of first axial and traverse openings extending there through; a sheet engagement structure secured to the support structure, the sheet engagement structure having a plurality of second axial openings extending there through, the sheet engagement structure having a peripheral section and at least one connecting leg extending between portions of the peripheral section; a sheet securing ring removably secured to the sheet engagement structure for slidingly securing a sheet between the sheet securing ring and the sheet engagement structure; and the at least one central opening, plurality of first axial and traverse openings and the plurality of second axial openings cooperating to create a uniform and accelerated flow of fluid through the fixture. 
     In another aspect, the present invention is directed to a fixture for holding sheets having complex shapes during heat treating, the fixture comprising: a base having at least one central opening extending there through, the base defining a peripheral foundation; a support structure extending inwardly and upwardly from the base and across the central opening, the support structure having a plurality of first axial and traverse openings extending there through; a sheet engagement structure secured to the support structure, the sheet engagement structure having a peripheral section and a second axial opening extending there through; a gap defined between the peripheral section and the sheet engagement structure; a first plurality of tabs extending from the sheet engagement structure configured to engage one or more edge mounted tabs formed on the sheets; and the at least one central opening, plurality of first axial and traverse openings and the second axial opening cooperating to create a uniform and accelerated flow through the fixture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a heat-treating fixture of the present invention used for heating and quenching of sheets having complex shapes; 
         FIG. 2  is a top view of the heat treating fixture of  FIG. 1 ; 
         FIG. 3  is a front view of the heat treating fixture of  FIG. 1 ; 
         FIG. 4  is a back view of the heat treating fixture of  FIG. 1 ; 
         FIG. 5  is a right side view of the heat treating fixture of  FIG. 1 ; 
         FIG. 6  is a left side view of the heat-treating fixture of  FIG. 1 ; 
         FIG. 7  is a detail view of a portion of the heat-treating fixture of  FIG. 4 ; 
         FIG. 8  is a top view of the heat-treating fixture of  FIG. 1  wherein a sheet engagement structure includes tabs extending therefrom; 
         FIG. 9  is a detail view of a portion of the heat-treating fixture of  FIG. 8 ; 
         FIG. 10  is a front view of the heat-treating fixture of  FIG. 1  and a sheet securing ring with spacers attached thereto; 
         FIG. 11  is a front view of the heat-treating fixture of  FIG. 10  where the sheet securing ring with spacers is attached to the heat-treating fixture; 
         FIG. 12A  is a detail view of a portion of the heat-treating fixture of  FIG. 11 ; 
         FIG. 12B  is detail view of a portion of the heat-treating fixture of  FIG. 11  having a sheet positioned therein; 
         FIG. 12C  is a cross-sectional view of the portion of the heat-treating fixture of  FIG. 11  having a sheet positioned therein taken along line C-C of  FIG. 12B . 
         FIG. 13  is a top view of the sheet securing ring and spacers of  FIG. 10 ; 
         FIG. 14  is a detail view of a portion of the sheet securing ring and spacers of  FIG. 13 ; 
         FIG. 15  is a bottom view of the sheet securing ring and spacers of  FIG. 10 ; 
         FIG. 16  is a detail view of a portion of the sheet securing ring and spacers of  FIG. 15 ; 
         FIG. 17  is a left side view of another heat-treating fixture of the present invention used for holding a stack of sheets for aging of the sheets; 
         FIG. 18  is a right-side view of the heat-treating fixture of  FIG. 17 ; 
         FIG. 19  is a top view of the heat-treating fixture of  FIG. 17 ; 
         FIG. 20  is a top view of a portion of the heat-treating fixture of  FIG. 17 ; 
         FIG. 21  is a top view of a portion of the heat-treating fixture of  FIG. 17 ; 
         FIG. 22  is a left side view of the heat-treating fixture of  FIG. 17  holding a stack of sheets for aging of the sheets; 
         FIG. 23  is a right-side view of the heat-treating fixture of  FIG. 22 ; 
         FIG. 24  is a top view of a portion of the heat-treating fixture of  FIG. 22 ; 
         FIG. 25  is a top view of a portion of the heat-treating fixture of  FIGS. 23 ; and 
         FIG. 26  is a back view of the heat-treating fixture of  FIG. 22 . 
     
    
    
     DETAILED DESCRIPTION 
     A fixture  100  in accordance with the present invention is configured for holding one or more sheets having complex three-dimensional shapes, such as for example, a sheet having a predetermined shape as being produced by a hot-forming process. In one embodiment, the fixture  100  holds the sheet during one or more heat treating processes, such as for example heating up to about 1000 degrees Fahrenheit and quenching to 70 to 90 degrees Fahrenheit. In one embodiment, the fixture  100  is configured to hold one sheet having a complex three-dimensional shape. In one embodiment, the fixture  100  is configured to hold a plurality of production sheets wherein each sheet has the same complex three-dimensional shape. 
     As shown in  FIGS. 1-7 , one embodiment of the fixture  100  includes a base  102  having at least one central opening  104  extending there through. The base  102  defines a peripheral foundation  103 . A support structure  106  having walls  107  extending inwardly and upwardly from the base and across the central opening  104 . The support structure  106  has a plurality of first axial openings  108  and traverse openings  110  extending there through. The fixture  100  includes a sheet engagement structure  120  secured to the support structure  106 . 
     The sheet engagement structure  120 , having an upper engagement surface  120 A, is configured to conform to the complex three-dimensional shape of the sheet. The sheet engagement structure  120  has a plurality of second axial openings  122  extending there through. The sheet engagement structure  120  has a peripheral section  124  and at least one connecting leg  126  extending between portions of the peripheral section  124 . The central opening  104 , the plurality of first axial openings  108 , the traverse openings  110  and the plurality of second axial openings  122  cooperate to create a uniform and accelerated flow of fluid through the fixture  100 , for example an atmosphere in a furnace during heating or a cooling medium such as glycol (e.g., 37 to 40 percent concentration) during quenching. 
     As shown in  FIGS. 10 and 11 , the fixture  100  includes a sheet securing ring  130  removably secured to the sheet engagement structure  120  for slidingly securing a sheet between the sheet securing ring  130  and the upper engagement surface  120 A of the sheet engagement structure  120 . In one embodiment, as shown in  FIGS. 13-16 , the sheet securing section  100  includes a plurality of spacers  132  secured thereto. The spacers  132  are of a predetermined thickness greater than that of the sheet (e.g., greater than 1 mm or 0.04 inches) to allow the sheet to slide between the sheet securing ring  130  and the sheet engagement structure  120  during heating and cooling. In one embodiment, the spacers  132  are secured to the sheet securing ring  130  prior to attaching the sheet securing ring  130  to the sheet engagement structure  120 . 
     As shown in  FIGS. 11 and 12A-12C , a channel  125  is formed between the peripheral section  124  of the sheet engagement structure  120  and the sheet securing ring  130 . A sheet  10  is positioned within the channel  125  wherein the sheet  10 , during a heat-treating process, may expand and/or contract, or float, in one or more of an X direction, a Y direction and a Z direction, resulting from such heat-treating process. As a result, the sheet  10  further conforms to the predetermined shape being produced by the hot-forming process. 
     In one embodiment, as further shown in  FIGS. 8 and 9 , the base  102 , the support structure  106  and/or the sheet engagement structure  120  has a plurality of tabs  140 A extending therefrom for engagement with a corresponding plurality of tabs  140 B extending through the sheet securing ring  130  (the plurality of tabs  140 A and the plurality of tabs  140 B collectively referred to herein as tabs  140 ). The sheet securing ring  130  and/or the sheet engagement structure  120  has a sliding enhancement coating  141 ,  142  applied respectively thereto. In one non-limiting embodiment, the sliding enhancement coating  141 ,  142  is boron nitride. 
     The base  102 , support structure  106 , sheet engagement structure  120 , the sheet securing ring  130  and the spacers  132  are manufactured from a suitable metal such as but not limited stainless steel. The base  102 , support structure  106 , sheet engagement structure  120 , the sheet securing ring  130  and the spacers  132  are secured to one another via suitable method including but not limited to welding. 
     As shown in  FIGS. 17-21 , a fixture  200  in accordance with the present invention is configured for holding a stack of sheets  300  having complex shapes for aging the sheets as shown in  FIGS. 22-26 . The fixture  200  is similar to the fixture  100  and has a base  202 , a support structure  206  and sheet engagement structure  220  having a peripheral section  224 , but no connecting legs. Instead, there is a gap  221  between the peripheral section  224  and the sheet engagement structure  220  to allow the sheets  300  to sag as needed. 
     The sheet engagement structure  220  has a plurality of tabs  240 A and/or  240 B extending therefrom for engagement with one or more edge mounted tabs  340 A and/or  340 B integrally formed on the sheets  300 . The tabs  240 A are secured to the tabs  340 B in a suitable number of locations (e.g., two locations shown) with suitable fasteners  250 . In one embodiment, the stack includes 5 to 20 sheets. 
     Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those of skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of the appended claims.