Patent Application
20120047986
1. Technical Field
This application relates to a sheet metal forming die having a rotary cam that is used to form complex shapes.
2. Background Art
Sheet metal panels are formed on die sets that form a sheet metal blank into a desired shape in a series of steps including dies for drawing, trimming, flanging, piercing and other operations in a series of steps. Traditionally, such die sets included an upper die that is reciprocated relative to a fixed lower die to perform a desired operation on a sheet metal panel or blank. Forming cams may be carried by the upper die to form various surfaces that may not be easily formed with a die that moves in a vertical reciprocating motion. Rotary cams are used to support or back up portions of panels that define undercuts or other complex shapes. Rotary cams are cylindrical in shape and are pivoted between a forming position and a retracted position. Rotary cams are pivoted to the retracted, or unload, position to permit the panel to be removed from a die after forming around an undercut or complex area.
To form complex shapes on some panels, it was previously necessary to provide multiple dies for flanging complex curve shapes. Using multiple dies for flanging increases dimensional variation and may adversely affect the appearance of the finished panel due to variation in part to die locations. Conventional rotary cams when used in flange dies may not be capable of directly flanging the part due to the die/part interference when the rotary cam is retracted to unload the part. This is an inherent limitation of conventional rotary cam designs and may result in flange bypass locations on complex parts. Flange bypass locations are areas where there are gaps between flanging surfaces on a die used to form a flange. Flange bypass locations may also adversely affect flange appearance in the finished panel.
The tooling approach developed by Applicants addresses the above problems and others that will be apparent to one of ordinary skill in the art.
The die set developed by Applicants includes a rotary cam that is assembled within a cradle in a lower die. A die insert is cantilevered over the rotary cam on at least one end of the rotary cam that has a reduced diameter. The die insert rests on the top of the reduced diameter portion of the rotor to provide support for the cantilevered die insert during a flanging operation. The die insert and reduced diameter end of the rotary cam are machined to a matching frustoconical or spherical shape that defines a common radius as viewed normal to the rotor center line. The radius may vary over the length of the insert. Every section is a true radius to permit rotation of the rotary cam including the reduced diameter section about the pivot access of the rotary cam. The rotary cam has an outer surface that is cylindrical in shape and has a cylindrical radius. A radius of the bullet nose, or reduced diameter section, is between zero and the radius of the cylindrical body portion of the rotor.
The insert and reduced radius portion of the rotary cam permits direct flanging over areas of a panel that are back angled to the direction that the rotor retracts. The increased flexibility provided by the cantilevered die insert and reduced radius portion of the rotary cam can be used to reduce the number of flange bypass locations on a panel. The cantilevered die insert facilitates providing a variable diameter rotor in a critical location.
According to one aspect of the disclosure, a die set is provided for forming a panel in a press. The die set includes an upper die that is adapted to be set in the press. A lower die is also adapted to be set in the press to cooperate with the upper die. A rotary fill cam is assembled to the lower die. The rotary fill cam is pivoted about an axis and includes a cylindrical portion and a reduced diameter portion on at least one end. A cantilevered flange die insert is secured to the lower die to extend over the reduced diameter portion of the rotary fill cam. The cantilevered flange die insert fills the space between the upper die and the reduced diameter portion of the rotary fill cam.
According to another aspect of the disclosure, a rotary fill cam is operatively assembled to a die. The rotary fill cam includes a body portion that is assembled to the die to pivot within the die. A bullet nose portion is provided on one end of the body portion that pivots with the body portion. The die has a cantilevered flange die insert that overhangs the bullet nose portion of the rotary fill cam and is supported by the bullet nose portion in a forming operation.
According to yet another aspect of the disclosure, a die assembly is provided that is used to form a panel. The die defines a cavity in which a rotary cam is received. The rotary cam has a cylindrical portion and a re-entrant portion. A cantilever extension is attached to the die and extends into the re-entrant portion. A first forming surface is provided on the extension and a second forming surface is provided on the rotary cam that is rotated to a position adjacent to the first forming surface to form a portion of the panel.
According to other aspects of the disclosure, the re-entrant portion may have a partially spherical convex surface and the extrusion may have a partially spherical concave surface that are assembled together. A second die may be provided that includes a third forming surface that engages the panel on the opposite side of the panel from the first and second forming surfaces when they are adjacent to each other. The rotary cam rotates the second forming surface to a position that is not adjacent to the first forming surface to facilitate removal of the panel from the first die.
These and other features and aspects of the disclosure will be better understood in view of the attached drawings and the following detailed description of the illustrated embodiment.
Referring to
Referring to
The panel 30 may also be formed against an undercut forming surface 32 that is also provided on the nose portion 20 of the rotary cam 12. An undercut forming surface 32 may also be provided on the nose portion 20. The panel 30 may be formed against the undercut forming surface 32 when the panel 30 is formed.
An upper die 36 reciprocates relative to the lower die (not shown in
Referring to
Referring to
Although embodiments of the invention have been disclosed, it will be apparent to persons skilled in the art that modifications may be made without departing from the scope of the invention. All such modifications and equivalents thereof are intended to be defined by the following claims.
