Metal deforming – By relatively receding work-engaging tool-faces
Patent
1981-03-03
1983-08-09
Crane, Daniel C.
Metal deforming
By relatively receding work-engaging tool-faces
72293, 72370, 29252, 292835, 29523, B21D 4102, B23P 1100
Patent
active
043971733
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
Technical Field
This invention relates generally to a tube expander for extrudably expanding the walls of a tubular member into the bore of a flange, and more particularly to such a tube expander having an annular forming member moveably mounted on a mandrel.
Background Art
Devices for expanding tubular members are well known in the industry. Generally, such devices employ a plurality of forming members expandably mounted on a tapered mandrel. After clamping and insertion into a tube, the forming members are radially extended to a predetermined diameter, and the tube is expanded to a requisite dimension in a single, unidirectional stroke as the tool is withdrawn. In addition to various expandable member forming devices, solid punches are used to extrudably form the walls of tube in a single, unidirectional stroke as the punch enters the workpiece.
It is necessary that the tube be securely clamped or otherwise restrained during deformation to prevent slippage of the tube with respect to the expander. In particular, in punch forming the amount of clamping force applied to the tube must be limited to avoid crushing, marring, or otherwise damaging the tube or tube surface. The single stroke forming actions of the above-described prior art devices are therefore inherently limited in that the axial forces applied during the single deformation stroke must not exceed the clamping forces on the tube, which in turn, must not be so great, that the tube will be damaged, as set forth above.
The present invention provides a tube expander that is not limited to forming during a single stroke and is directed to overcoming one or more of the problems as set forth above.
Disclosure of the Invention
In accordance with one aspect of the present invention, a tube expander for extrudably expanding the walls of a tube includes an annular forming member moveably disposed on a mandrel. The annular forming member has a generally circular cross section and is moveable between a first position at which the annular forming member is at a skew angle with respect to the longitudinal axis of the mandrel and a second position at which the forming member is normal to the longitudinal axis of the mandrel.
Current tube expanders, by their construction, are generally limited to forming a tube during a single stroke. For example, a solid punch type expander will extrude the wall of the tube as the punch enters the tube. An expanding element forming tool, such as a rotary expander, extrudes the tube wall as a mandrel of the tool rotates and is drawn into the tube. Both of these constructions are limited by the magnitude of the nondestructive clamping force which are available to resist the axial component of the extrusion forces.
The present invention provides a tube expander for partially forming the tube during insertion of the expander into the tube and fully forming the remainder during withdrawal of the expander. Preferably, about 50% of the tube is formed during the insertion operation. By dividing the tube deformation into two strokes of the expander, insertion and withdrawal, the clamping forces required for a given total amount of tube deformation are greatly reduced. The resultant reduced clamping requirements greatly reduce the possibility of structural and surface damage to the tubes.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric view of an embodiment of the present invention with portions broken away to show details of the assembly.
FIG. 2 is a partial longitudinal section of an embodiment of the present invention with the mandrel disposed in a contracted position substantially within the housing.
FIG. 3 is a partial longitudinal section of an embodiment of the present invention with the mandrel disposed at an extended position.
FIG. 4 is a partial longitudinal section of an embodiment of the present invention with the mandrel extended and the annular forming member positioned normal to the longitudinal axis of the mandrel.
FIG. 5 is a cross section of an embodiment of the present invention taken
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patent: 4027522 (1977-06-01), Clavin
Eftefield Larry G.
Horton Edward R.
Caterpillar Tractor Co.
Crane Daniel C.
McFall Robert A.
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