US3036370A - Fabrication of hollow articles - Google Patents

Description

May 29, 1962 D. K. BLElKAMP ETAL 3,036,370

FABRICATION OF HOLLOW ARTICLES Filed Dec. l0, 1956 United States Patent O 3,03,370 FABRECATIN E HGLLOW ARTICLES Donaid K. Bleiiramp, Berkeley, Mo., and William V. Wenger, Wood River, lll., assignors to Olin Mathieson Chemical Corporation, East Alton, lli., a corporation of Virginia Filed Dec. it), 1956, Ser. No. 627,432 8 Claims. (Cl. 29-157.3)

This invention relates to the fabrication of hollow articles, more particularly to an improved apparatus and method for forming the hollows in such articles.

The invention is more particularly directed to an apparatus and method for expanding hollows in panels of the type disclosed in U.S. Patent 2,690,002, although the blank from which the hollow panel is formed may be fabricated by other methods. Certain features of the aforementioned patent will be described to facilitate a clear understanding of the invention. The panels described in the aforementioned patent are fabricated by applying a pattern of weld-inhibiting material to a sheet of metal, superimposing a second sheet of metal on the first sheet with the pattern of weld-inhibiting material sandwiched between the sheets, and welding the two sheets together in their entire adjacent areas not separated by the weld-inhibiting material by rolling. The resultant panel is elongated in the direction of rolling and the adjacent faces of these sheets are welded together throughout their entire area not separated by the pattern of weld-inhibiting material. A fluid pressure is then injected into the unjoined portion of the panel to outwardly distend the sheets in the area of the weld-inhibiting material to form a hollow panel. The panel is posi--v tioned between rigid spaced apart pressure pads and a fluid pressure is then injected into the unjoined portion o f the blank to outwardly distend the sheets into rrn engagement with the pads thereby providing the hollows with ilat outer surfaces. Hollow panels of this type often require relatively large hollows which serve as tubes or conduits for conveying a fluid. An example of such a panel may be found in an evaporator panel for refrigerators, in which is combined either a circuitous tube design in conjunction with a large boiler or accumulator. The expansion of large hollows of this nature have presented many problems, such as rupturing of the walls of lthe large hollow where it joins the solid web of the panel, and warping of the web and tube portion of the panel because of the strain resulting from the expansion of the large hollow. The tendency of the large hollow to rupture can be retarded by permitting the web portion of the panel to pull in, or draw in toward the large hollow thereby permitting a greater outward expansion of the large hollow. However, such drawing in of the panel inevitably results in warping the web and tube portion of the panel. If the web portion of the panel is iirmly clamped during expansion of the large hollow, such warping is not likely to occur, but under these circumstances, the web and tube portion of the panel cannot.

draw in towards the large hollow and the walls of the large hollow are therefore more likely to rupture.

In expanding such large hollows the present invention comprehends positioning the blank between pressure pads spaced iapart just slightly more than the thickness of the blank, the pads having a cut-out portion adjacent the unjoined inner portion of the blank which is to form the large hollow. When the panel has been initially expanded -to provide hollows having outer surfaces, the aforementioned difficulties can be overcome by further expanding thedesired 4large hollows as follows. The initially expanded panel is positioned between rigid pressure pads having a cut-out portion to permit additional expansion of the desired large hollow while preventing ICC warping of the web and tube portion of the panel. 'I'he web and tube portion of the panel should not be tightly clamped between the pads because it is desired that the web and tubes be permitted to draw in toward the large 5 hollow. Large expenses of web devoid of expanded tubes may be restrained against warping by the provision of blocks between the pads and the web, or by protrusions on the pads. Preferably the pads are spaced apart a distance slightly greater than the outwardly expanded dimensions of the tubes to prevent crushing the tubes as the pads are brought together. Under these circumstances, upon injection of a fluid pressure into the previously expanded hollows, the tubes are expanded slightly into engagement with the pads and the large hollow will be free to expand a much greater amount than the tubes, thereby providing a hollow portion of substantially greater volume than was obtained during the` initial expansion.

It is therefore an object of this invention to provide an improved method and apparatus for forming relatively large hollows in hollow panels.

Another object of this invention is to provide an mproved hollow panel.

Additional objects and advantages will become apparent from the following description and drawings from which:

FIGURE 1 is a perspective view of a sheet of metal havin-g a pattern of weld-inhibiting material applied to a surface thereof.

FIGURE 2 is a schematic perspective view of the sheet as shown in FIGURE l having superimposed thereon a second sheet of metal with the pattern of weld-inhibiting material sandwiched between the sheets and showing the sheets being welded together While passing through a pair of mill rolls.

FIGURE 3 is a schematic sectional view of the resultant blank of FIGURE 2 positioned between a pair of rigid spaced apart pressure pads and expanded to form a hollow panel, the portion of the pattern of weld-inhibiting material forming these hollows being indicated by the line 3 3 in FIGURE l.

FIGURE 4 is a schematic perspective view of an embodiment of restraining pads and blocks for use in subsequent expansion of the hollow panel shown in FIG- URE 3.

FIGURE 5 is a schematic sectional view of the panel shown in FIGURE 3 positioned on the pad and blocks shown in FIGURE 4, with another embodiment of a similar pad positioned atop the panel, the section of the lower pad and block assembly being indicated by the line 5 5 in FIGURE 4, and the section of the panel being the same as in FIGURE 3.

FIGURE 6 is a schematic sectional view similar to FIGURE 5 after the hollow panel has been further expanded.

Referring to the drawings, FIGURE l illustrates a sheet of metal l having applied to a clean surface 2 a pattern of weld-inhibiting material 3. The pattern of weld-inhibiting material includes a strip 4 terminating at an edge of the sheet, a plurality of interconnected strips 5 and a relatively large area 6 interconnected with the strips 5. FIGURE 2 shows the sheet l having superimposed thereon a second sheet 9 with the pattern of weld-inhibiting material 3` sandwiched between the sheets. The sheets 1 and 9 are tacked together as by spot-welds l0 to prevent relative slippage between the sheets as they are subsequently welded together by passing through a pair of mill rolls 11 to form a blank 12. It is normally necessary that the sheets l and 9 be heated prior to passing through the mill rolls to assure that they weld to each other in keeping with techniques well known in the rolling art. The sheets il scesero Referring to FIGURE 3, the resultant blank 12 is positioned between'a pair of spaced apart pressure pads 16. The pressure pads i6 are on relatively movable jaws i A nozzle is inserted into the inlet 4 and l 17 of a press. the unjoined portion of the blank is expanded into firm engagement with the rigid pressurepads 16 resulting in hollows 18 throughout the blank. These hollows all have flat outer surfaces 19 through engagement with the pads 16. The strips of the weld-inhibiting pattern 3, shown in FIGURE l, form tubes 20 and theV area 6 forms the large hollow 2,1. The hollows are separated from each other by solid webs 22. Circumscribing the tubes is a solid flange 23. The iluid pressure within the hollow 18 is now released into pressure pads 16 and press jaws 17 spaced apart a greater distance to permit removal of the hollow panel 24.

The large hollow 21 is now expanded" a greater amount by positioning the panel 24 between the restraining means shown-in FIGURE 5. -The .lower restraining means 2.7 is shown in perspective in FIGURE 4 and includes a rigid restraining pad 28 having a cut-out portion 29. Bositioned onftop surface 3i) of the pad 28 are a number of blocks 31, 32, 33, and'34. These blocks are slightly thinner than half the total loutwardly expanded dimension of the hollows 13, less half the thickness of the web 22.0f the expanded panel 24. In other words, the blocks are slightly less than half` the spacing between-the pads16, shown in FIGURE 3, less half the thickness of the panel web 22. The upper restraining means 35 is similar to the lower restraining means 27 except that ,the blocks 31-34 lare replaced by integral protrusions such as 36 and 37. The large-hollow 21 is positioned on the lower restraining means 27 adjacent the cut-out 29. The blocks 31-engage the web 22 and the blocks 32-34 engage a portionof the solid flange 23. All edgesof the 'blocks SL34, and the protrusions such as 36 and 37 should be rounded olf adjacent the panel 24 to prevent mari-ing the surface of the panel. The web 22 should be firmly held inthe press, but should not be tightly clamped between the` restraining means 27 and 35. The tubes 20 or other hollows should be slightly spacedfrom the adjacent portions of the restrain- The blocks 31 or the protrusions 36 should be so positioned 4that any large expanse of web which is devoid of tubes 20 or other hollows, is restrained against warping. It is also desirable thatV the panel flange 23 be prevented from warping by use of similar blocks 32-34 or protrusions as 37. Portions of the flange which are -to be trimmed from the iinished panel need not be restrained Y against warping or buckling as this warped portion may be trimmed from the panel.

The restraining means 27 and 35 may be interchanged but if blocks are used in conjunction with the upper restraining means 27 and 35 they will have to be either individually positioned on the panel 24 after it has been placed Yin the press, or alternately they will have to be permanently secured to the pad 28. If only a few panels are to be fabricated, it will be more economical to position the blocks 31-34 on the pad 28 and then properly position the panel 24 on the pad and blocks. Subsequently, additional blocks are positioned appropriately on the upper surface of the panel 24. When the panel has received an initial expansion, the positioning of the blocks is a relatively simple matter. When a larger number of panels is to be fabrica-ted, it will be more economical to use a preformed restraining means such as 35, in which event the ing means 27 and 35 as will occur if the blocks or protr'usions-are of the proper thickness as previously described. Such blocks or protrusions are only necessary to prevent distortion of relatively large areas of web, that is, areas devoid of tubes or other hollows. The restrainingmeans 27 and 35 may very lightly engage the tubes 20- but it is preferable that they be spaced therefrom to assure that the tubes will not be crushed when the re-V straining means arebrou'ght together.V WithV the panel 24 positioned between restraining means 27 and 35 las shownin FIGURE 5, and lwith the nozzle secured in the inlet, a duid pressure is'injected into the hollows to further expand the panel to the condition shown in FIGURE 6.

During Ithe second expansion the tubes 20 are again expanded into irm engagement with lthe restraining means 27 and 35 and the large hollow 21 is expanded into the opening 29 in the lower means 27 and into a Vsimilar opening in the restraining means 35. The panel is lfree to be drawn in toward the-large hollow. 2l because it is not tightly clamped between the restraining means 27 and 35. However, warping or buckling of the panel is prevented by the restraining means 27 and 35 because of the very small clearance between the restraining means and the panel. The ability of the panel to draw in is increased by applying a lubricant to the restraining means 27 and 35. The fluid pressure within vthe panel is' released and the jaws 17 of the press are spaced apart permitting removal of the finished panel 40. The nished panel may then be trimmed as so desired. v f

protrusions such as 36 and 37 and the cnt-out corresponding to the cut-out 29 in the restraining means 27 should be placed close to the large hollow 21 as manufacturing tolerances will allow.

Although this invention has been described with particulai reference to certain embodiments, details, and techniques, various changes will be apparent to one skilled in lthe art, and the inventionis therefore not to be limited to such embodiments, details, and techniques except as set forth in the claims.

We claim:

l. The method of expanding a panel formed of super'- imposed Isheelts having selected portions of their adjacent surfacesY joined together to deti-nebetween said sheets a pattern of internally unjoinedV portions distended outwardly a iirst amount to bulge out of said panel in a correspending desired configuration of internal hollows adapted to coniine a liuid with said hollows comprising a first hollow portion and a second hollow portion, and with said first hollow portion placed in intercommunca tion with s-aid second hollow portion, said lmethod cornprising positioning said panel between rigid restraining pads disposed opposite said hollows, at least one of said pads having a void encompassing said first hollow portion with Ithe remainder of said one pad having surfaces disposed ladjacent the portion of said panel opposite said second hollow portion to limit disten'tion of said second hollow portion during subsequent expansion, and injecting fluid pressure into said hollows to further distend by expansion said rst hollow portion into said void suiiiciently to bulge said iirst hollow portion out of said panel to a degree greater than said given iirst amount 4and to a degree greater than that of said second hollow pontion while simultaneously permitting said panel :to freely draw in towards said first hollow portion in 'the plane of said panel during said expansion. t

2. In -a pressure Welded element having a distended internalV inter-connected fluid passageway system contained therein comprised of a first hollow pontion and a second hollow pontion with both said portions distended a tirst amount and with said first hollow portion placed in intercommunication with saidV second hollow portion, a method for further dis-tending said rst hollow portion of said passageway system comprising a further distention by expansion of said passageway system with said panel disposed between rigid Vrestraining pads positioned op-v said second hollow portion to limit distention of said second hollow portion during said expansion with said expansion comprising injecting .into said system of passageways a fluid pressure to further expand said first hollow portion encompas-sed by said voids sufficiently to bulge lsaid rst hollow portion out of said panel to a degree greater than the safid given amount and to a degree greater than said second hollow portion while simultane- -ously permitting the remainder of said panel to freely draw-in in its plane between said pads towards said expanding first hollow portion.

3. A method of forming a relatively large passageway in a pressure welded panel having an internal interconnected uid passageway system adapted to confine a fluid formed therein and comprised of a first hollow portion anda second hollow portion with both said first and second hollow portions distended a first amount to bulge out of said panel, said method comprising an expansion of said passageway system with the portion of said panel opposite said second hollow portion restrained against distention lbetween a pair of opposed restraining pads disposed adjacent said panel, said pads having surfaces disposed opposite said second hollow portion and including protrusions on said surfaces disposed adjacent the pressure welded web surrounding the inter-connected passageway system with said pads having a void opposite said first hollow portion to permit further distention thereof to a degree greater than said first amount, said expansion comprising injecting into said passageway system a fluid pressure to obtain said further `distention of said first hollow portion outwardly of said panel into said void with said further distention being sufficient to distend said first hollow portion outwardly of said panel to a degree greater than that of said second hollow portion while simultaneously permitting the remainder of said panel to freely draw-in in its plane between Said pads toward said first hollow portion during said further distention whereby said panel is prevented from distorting out of its plane in which said draw-in occurs.

4. A method of distending a panel formed of superimposed sheets having selected portions of their adjacent surfaces joined together to define between said sheets a pattern of internally unjoined areas corresponding to a desired configuration of uid passageways adapted to confine a fluid with said unjoined areas comprising a first unjoined area and a second unjoined area with said rst unjoined area placed in intercommunication with said second unjoined area, said method comprising distending said unjoined areas -a first amount, and further distending by expansion said first unjoined area sufficiently to distend it a second amount outwardly of said panel to a degree greater than said first amount while hunting the distention of said second unjoined area outwardly of said panel to restrain the distention of said second tmjoined area `below said second amount, `and simultaneously with said expansion permitting said panel to freely draw-in in its plane whereby transverse distortion of said panel is restrained.

5. A method of distending a panel formed of superimposed sheets having `selected portions of their adjacent surfaces joined together to define between said sheets a pattern of internally unjoined areas corresponding to a desired configuration of fluid passageways adapted to confine a uid and with said areas comprising a first unjoined area and a second unjoined area with said first unjoined area placed in intercommunication with said second unjoined area, said method comprising distending said unjoined areas to the first amount desired in the portion of said fluid passageways corresponding to said first unjoined area, and expanding said first unjoined area to distend it outwardly of said panel an additional amount desired in the portion of said `fluid passageways corresponding to said first unjoined area While simultaneously limiting distention of said second unjoined area out of said panel below said additional amount and while simultaneously permitting free movement of said panel in its plane during said additional expansion whereby said panel is restrained against transverse distortion during said additional expansion.

6. The method of preventing distortion during the distention of a panel formed of superimposed sheets having selected portions of their adjacent surfaces joined together to ldefine between said sheets a pattern of unjoined portions corresponding to a desired system of internal fluid passageways with said unjoined portions initially distended a first amount to bulge out of said panel to form an intermediate configuration of said system of fluid passageways with said distended hollows comprising a first hollow portion and a second hollow portion with said first hollow portion placed in intercommunication with said second hollow portion, said method comprising distending by expansion said first hollow portion to bulge out of said panel an amount greater than said first amount and an amount greater than said second hollow portion and simultaneously limiting distention of said second hollow portion out of said panel `below the second said amount while simultaneously permitting free movement of said panel in its plane whereby said panel is restrained against transverse distortion.

7. The method of distending a panel `formed of superimposed sheets having selected portions of their adjacent surfaces joined together to define between said sheets a pattern of internally unjoined portions corresponding to a desired system of internal tubular hollows adapted to confine a fluid within said panel with said unjoined portions being distended a first amount to bulge out of said panel into an intermediate configuration of said corresponding system of internal tubular hollows wherein said tubular hollows comprise a first tubular hollow portion and a second tubular hollow portion with said first tubular hollow portion placed in intercommunication with said second tubular hollow portion, said method comprising positioning said panel between rigid restraining pads spaced apart an amount slightly greater than the initial first amount of distention of said hollows, said pads having a void opposite to and encompassing portions of said faces opposite said first hollow portion to permit additional distention of said first hollow portion to the degree desired in corresponding portions of said system of internal tubular hollows with the remainder of said pads having surfaces disposed adjacent the portion of said panel opposite said second hollow portion to, both, limit distention of said second hollow portion in a direction normal to said panel and to permit movement of said panel within its plane between said pads, injecting into said hollows a distending Huid pressure to distend said second hollow portion into firm engagement with adjacent portions of said pads and to further distend said first hollow portion into said void to a degree greater than said first amount and greater than the distention of said second hollow portion while simultaneously permitting said panel to freely draw-in in its plane.

8. The method of expanding a panel formed of superimposed sheets having selected portions of their adjacent surfaces joined together to define between said sheets a pattern of distended unjoined areas adapted to confine a fluid and corresponding to a configuration of hollows desired internally within said panel with said unjoined areas comprising a first unjoined area and a second unjoined area with said first unjoined area placed in intercommunication with said second unjoined area, said method comprising expanding said rst unjoined area to obtain in said first unjoined area an additional amount of distention out of the plane of said panel desired in the corresponding portion of said hollows while simultaneously restraining distention of said second unjoined area outwardly of said panel below said additional amount and while simultaneously permitting free movement of said panel in its plane during said expansion whereby said 7k panelv is restrained against distortion transverse the plane of said panel during said expansion.

References Cited in he le of this patent UNITED STATES PATENTS 2,243,809 Wendel May 27, 1941 2,498,275 Johnson V Feb. 21, 1950 2,582,358 Schoellerman Jan. 15, 19,52

8 Kranenberg Aug. 18, 1953 Long Dec. 15, 1953 Grenell Sept. 28, 1954 Simmons Q--- Apr. 3, 1956 Watter Aug. 19, 1958 Adams Nov. 11, 1958 Rieppei Apr. 21, 1959 Simms Aug. 11, 1959

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