US 3566661 A
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March 2, 1911 G. P. ETAL 3,566,661
METAL FORMING Fild July 29', 1968 K1 1. (Prior ark) I ---%Bi l X INVENTORS. Gerald M Caflerfy. Fredenck Rudolphlr. BY Harry [2 Sch on wmu, R. VLJLI;
AGENT v United States Patent Office Patented Mar. 2, 1971 3,566,661 METAL FORMING Gerald P. McCalferty, Churchville, Pa., Frederick Rudolph, Jr., Cherry Hill, N.J., and Harry P. Schane,
Lafayette Hill, Pa., assignors to The Budd Company,
Filed July 29, 1968, Ser. No. 748,444 Int. Cl. B21b 1/00; B21c 37/02; B23p 17/00 US. Cl. 72--365 3 Claims ABSTRACT OF THE DISCLOSURE A method of metal forming, as by rolling, a thin sheet metal part such as titanium in pack fashion whereby the part to be formed is sandwiched between inner and outer cover sheets of sufficient strength to provide support for the thin part. The cover sheets are mechanically restrained from slippage by edge welding.
The forming of sheet metal parts which have non planar shapes and which are composed of a low elongation material such as titanium has generally been formed by a step expansion process. An expansion process whether mechanical or hydraulic is limited to a safe percentage of elongation of the material before stress relieving and reexpanding. As a result, if a part contains radical bend radii or shapes requiring large percentages (IO-20%) of stretch, multiple and costly operations must be performed to complete the part formation.
It is an object of this invention, therefore, to provide an improved method of metal forming which avoids one or more of the disadvantages of the prior-art methods and which has improved efficiency.
It is still another object of this invention to provide an improved method as by a rolling process of forming an object of non-planar shaped cross sectional contour, which circumvents the multiple and costly operations previously used in forming such parts.
For a better understanding of the present invention together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.
In the drawings FIG. 1 is a view of one form of a prior-art arrangement showing an elevational view of a support form and a cooperable roller element for rolling a bead in a thin walled titanium blank;
FIG. 2 is an elevational view of a support form and roller apparatus and embodying the method of the present invention;
FIG. 3 is an elevational view of the metal forming apparatus of FIG. 2 showing the metal blank pack being subjected to radical bend radii;
FIG. 4 is a view similar to FIG. 2 and illustrating a modified form of the invention.
This invention is useful in avoiding multiple stretching and intermediate stress relieving operations. With certain types of titanium the total amount of stretch forming may be extended as high as 11%. Expansion, however, being generally limited to 2 to3 percent per stretching operation as for example with 6AL, 4V titanium alloy, leads to multiple operations with stress relieving steps therebetween.
As a proposed solution to this problem it has been suggested to perform preliminary forming operations before endeavoring to obtain the final size of an object on an expansion machine. Such forming operation may be accomplished by rolling or beading the end bend radii inward thereby removing the major amount of percentage expansion required and allowing a single sizing operation in the order of 2 percent stretch.
Referring to FIG. 1 a thin sheet of material 10, such as titanium is shown contacting a cylindrical support 11. The support form includes an encircling groove 12 adjacent one end thereof and terminates in a stepped shoulder 13 which enables the support form 11 to be gripped for rotation as for example in a lath chuck, not shown. A roller 15 mounted for rotation about axis 17 may be moved toward and away from the titanium work piece 10 in in-line relationship with groove 12 as indicated by arrow A. The latter groove 12 includes outer radial surfaces 18. It has been found that upon advancing the feed of the roller 15 inwardly to engage the titanium blank while rotating the support form 11 about its axis, the results were unsatisfactory. The thin titanium sheet buckled and wrinkled badly over both radii portions as at 18 of the groove 12. It is believed that the buckling was due to lack of support over the area indicated as at 20 between the radii marginal edges 18 of groove 12 and the outermost peripheral tangent edge 21 of roller 15.
Referring now to FIG. 2 and in accordance with the present invention, a thin titanium blank 10 is shown engaged by an inner cover sheet 25 and an outer cover sheet 27. The cover sheets 25 and 27 are larger in area than the blank 10 and extend beyond the right hand edge 10a of the blank as seen in FIG. 2. In order to prevent relative slippage of the inner cover sheet 25 relative to the outer cover sheet 27, the marginal edges of the sheets may be welded as at 30, 31. When so secured together the titanium sheet 10, and cover sheets 25, 27 constitute a sandwich pack 32. Thereafter die set means 33 including a support form 34 and roller means 35 is provided. The support form 34 includes a groove 36 extending inwardly from its external surface 37. The support form may include a chuck land 37 of smaller diameter than that defined by external surface 37 to enable the support form to be rotated about its longitudinal axis by lathe means not shown. The roller means 35 are of smaller width than groove 36 and are in addition suitably mounted for rotation about axis XX parallel to that of the axis of support 34. The roller means 35 are adapted to be moved normal to the axis XX as indicated by the arrow B. The sandwich pack 32 is placed upon the support form so that the inner cover sheet 25 coacts with the external surface 37 of the support form to span groove 36 and thereafter the roller means 35 are bodily moved toward the groove 36 to coact with the external cover sheet 27. Upon exerting sulficient mechanical pressure inwardly while rotating the support form 34, the outer cover sheet 27, the blank 10 and the inner cover sheet are deformed and caused to enter the groove 36 as seen in FIG. 3. Thereafter the roller may be removed out of engagement with the sandwich pack. The inner and outer cover sheets may then be out along the lines Y-Y to remove the edge weld fastening 30. The top cover sheet 27 is then suitably removed from engagement with the blank 10 and the latter in turn removed from contact with the inner cover sheet 27.
With reference now to FIG. 4 there is shown a modified form of the invention. The roller means 35 and the support form means 34 provided may be identical to those shown in FIGS. 2 and 3. A sandwich pack 42 is provided and consists of an inner cover sheet 43, outer cover sheet 45 and a thin blank of titanium 10 sandwiched therebetween. The inner cover sheet 43 is of greater thickness than the outer cover sheet 45 and both cover sheets 43, 45 are edge welded as at 46 to prevent slippage relative each other 10. The latter blank 10 is of smaller area than the cover sheets and includes an edge 10a offset from the edge weld 46. As previously stated relative to FIGS. 2 and 3 the roller means 35 may be moved inwardly to compress the material of the sandwich pack into the groove 36. Upon withdrawing the roller means the edge weld of the pack may be suitably removed as by cutting along line Y-Y and the inner and outer cover sheets removed from the thin titanium blank 10. It has been found that increases as to the width of the groove 36 or the radii 47 of the groove, may be more easily accommodated as a result of increasing the support for the blank by the provision of increasing the thickness of the bottom cover sheet 43.
While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from this invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.
What is claimed is:
1. A method of forming a metal sheet blank into an object of non-planar shaped cross sectional contour, comprising providing inner and outer metal sheets of an area exceeding that of said blank, said inner and outer metal member comprising a rigid support form having a surface portion defining a groove and said second die set member comprising a roller, disposing said sandwich pack in a position between said die set members with said inner sheet in a position to first enter said groove, and thereafter providing relative movement between said roller and said support to cause a portion of said sandwich pack to enter said groove to deform said blank whereby said blank is enable to slip relative to said inner and outer cover sheets to preclude thinning out of said blank during said deformation.
2. In the method as set forth in claim 1 wherein said inner metal sheet is of greater strength than said outer metal sheet.
3. In the method as set forth in claim 2 wherein said inner metal sheet is of greater thickness than said outer sheet.
References Cited UNITED STATES PATENTS 2,837,817 6/1958 Kelley 29--424 3,063,142 11/ 1962 Kroon 29-424 3,263,319 8/1966 Tifft et a1 29-423 3,460,367 8/ 1969 Subovici 72-365 1,648,046 11/ 1927 Fulton 138-121 3,143,794 8/1964 Martin-Hurst 29-454 CHARLES W. LANHAM, Primary Examiner R. M. ROGERS, Assistant Examiner U.S. Cl. X.R. 29-423; 72-379