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US 4,722,216 AGranted
Radial forging method
AssigneeGrotnes Metalforming Systems, Inc.
InventorVernon R. Fencl
Life of this patent
Estimating the term…
Abstract
A tubular metal workpiece undergoes radial forging employing shrink forming. A multiplicity of dies are arranged circumferentially around the workpiece and urged radially inwardly in a first shrink forming pass to decrease the diameter of the workpiece. The dies are retracted, the workpiece is rotated slightly and another shrink forming pass is performed. The workpiece is then advanced axially, and the procedure described above is repeated. Procedures are employed to prevent torsional deformation and radially outward extrusion of metal in the gaps between adjacent dies.
Claims21
A method for radially forging by shrink forming a tubular workpiece having a circular cross-section, said method comprising the steps of:
- surrounding the circumference of said workpiece with a multiplicity of closely spaced dies having die faces and positioned at a first predetermined axial location on the workpiece;
- the annular spacing between the centers of adjacent dies being no more than about 60.degree.;
- urging said multiplicity of dies radially inwardly on said workpiece without swaging, in a first pass, to squeeze the workpiece and decrease the outside diameter thereof at said first predetermined axial location;
- engaging, with each of said die faces during said urging step, a respective one of a first group of circumferential parts of the workpiece, there being a second group of circumferential parts located between die faces during said first pass;
- the dimension, in a circumferential direction, of each circumferential part in said second group being less than the dimension in a circumferential direction of each die face adjacent said circumferential part;
- retracting said dies radially outwardly after said first pass;
- rotating one of (a) said multiplicity of dies or (b) said workpiece, in relation to the other, in a first sense, until said second group of circumferential parts, which were located between die faces on said first pass, are substantially centered under said die faces;
- the position of said dies at said first predetermined axial location being maintained during said rotating step;
- urging said multipicity of dies radially inwardly on said workpiece without swaging, in a second pass, to compress the second group of circumferential parts at said first predetermined axial location;
- each circumferential part of said workpiece being engaged by a die face during at least one of said first and second passes at said first predetermined axial location;
- and subjecting said workpiece to deformation during said passes without forming a radially outwardly extending extrusion at any of said second group of circumferential parts.
8 more elements
A method for radially forging by shrink forming a tubular workpiece having a circular cross-section and inside and outside surfaces, said method comprising the steps of:
- contacting the outside surface of said workpiece with a multiplicity of closely spaced dies surrounding said workpiece and positioned at a first predetermined axial location on the workpiece;
- the angular spacing between centers of adjacent dies being no more than about 60.degree.;
- locating inside said tubular workpiece a mandrel having an outer surface portion axially aligned with said first predetermined axial location;
- urging said multiplicity of dies radially inwardly on said workpiece, without swaging, initially to squeeze the workpiece and to decrease the outside diameter and increase the thickness of the workpiece at said first predetermined axial location, until the inside surface of the tubular workpiece contacts said outer surface portion of the mandrel;
- urging said dies radially inwardly without swaging, after the inside surface of the workpiece has contact said outer surface portion of the mandrel, to further squeeze the workpiece and decrease simultaneously both the outside diameter and the wall thickness of the workpiece;
- allowing axial expansion of said workpiece to accomodate the totality of the workpiece material displaced as a result of the decrease in both said outside diameter and said wall thickness;
- and restricting the area of contact, at said first predetermined axial location, between said dies and the outside surface of the workpiece, to decrease the friction in an axial direction between the outside surface of the workpiece and said dies and between the inside surface of the workpiece and said outer surface portion of the mandrel;
- the dimension of said area of contact in a direction transverse to the circumference of the workpiece, during the totality of said two urging steps, being relatively small compared to the axial dimension of the workpiece and to the inside diameter thereof when the inner surface of the workpiece contacts the outer surface portion of the mandrel;
- the totality of the movement of said dies during the squeezing of said workpiece being in a radial direction.
6 more elements
Dependencies are inferred from the claim text.