Rotary hemming device

In a press having a reciprocating ram opposing a bed on which a bendable sheet material having an upset skirt is placed, a rotary hemming tool comprising:

• a saddle attached to the ram facing the bed, said saddle having a surface penetratingly extending between saddle longitudinal ends which defines a hemi-cylindrical groove cut along its length;
• rotatably disposed in said saddle groove, a generally cylindrical rocker having its cylindrical surface altered by a single flat surface portion extending its length and by lobes at the transition from said flat surface portion to said cylindrical surface, said rocker lobes of lesser radius than the circumference of said rocker;
• means for radially positioning said rocker so that said flat surface portion is initially positioned at a predetermined angle with respect to the direction of ram travel;
• means for preventing reverse rotation of said rocker beyond its initial radial position;
• an anvil having a flat outer surface, said anvil positioned and attached to the press bed in an opposing relationship to said rocker, the interaction of said anvil and said rocker forming a line of contact between said anvil flat outer surface along the length of said rocker initially on one of said lobes and transitioning to a portion of said flat surface portion as the distance between said rocker and said anvil diminishes with the downstroke of the ram and the contact between said rocker and said anvil causes said rocker to rotate in said saddle;
• means for limiting forward rotation of said rocker beyond a predetermined angle of radial rotation.

A method for hemming flat sheet material comprising the steps of:

• placing the sheet material in a press having a reciprocating ram and a bed and having attached to said press bed an anvil having a sidewall and having attached to said ram a rotary bender saddle having a surface defining a hemi-cylindrical groove along its length in which resides a generally cylindrical rocker, said rocker having a notch defined by two side walls with lobes of lesser radius than the circumference of said rocker at the transition between said side walls and said circumference of said rocker, said notch and said anvil having a complementary sidewall relief of less than ninety degrees;
• causing said ram to stroke toward said bed;
• contacting one said notch lobe against a portion of the sheet material supported by the bed to clamp the sheet material in place;
• continuing the stroke of the ram to rotate said rocker to convert a portion of the linear movement of said ram to rotational movement of said rocker such that the other said notch lobe moves against the unsupported portion of the sheet material causing the sheet material to bend about said anvil and against said sidewall to form a skirt on the sheet material having an obtuse angle with respect to the sheet material;
• transferring the sheet material with the upset skirt to a second press having a reciprocating ram and a bed and having attached to said ram a rotary bender saddle having a surface defining a hemi-cyclindrical groove along its length in which resides a generally cylindrical rocker, and attached to said press bed an anvil, said rocker having a flat along its length and further having a lobe at each transition between the circumference of the rocker and the flat, said two lobes having a radius less than the radius of said rocker, said anvil having a flat outer surface the plane of which is approximately perpendicular to the direction of ram stroke, said rocker and said anvil positioned for their line of interaction to initially occur at one said lobe and to transition to said flat as said rocker is rotated by the downward stroke of said ram;
• causing said press ram at this said station to downstroke;
• contacting the upset skirt with said rocker flat causing said flat to bend the skirt toward the sheet material;
• contacting said anvil with said rocker on one said lobe causing said rocker to rotate and said line of interaction between said rocker and said anvil to transition to said flat, said flat thereby positioned substantially perpendicular to the direction of ram stroke and pressed against the skirt to coin the skirt against the sheet material to produce a controlled, gentle bend between the skirt and the parent material without spring back and without marring of the sheet material.

In a press having a reciprocating ram opposing a bed on which a bendable sheet material having an upset skirt is placed, a rotary hemming tool comprising:

• a saddle attached to the ram facing the bed, said saddle having a surface penetratingly extending between saddle longitudinal ends which defines a hemi-cylindrical groove cut along its length facing the bed;
• rotatably disposed in said saddle groove, a generally cylindrical rocker having its cylindrical surface altered by a flat extending its length and by lobes at the transition from said flat to said cylindrical surface, said rocker lobes of lesser radius than the circumference of said rocker;
• an anvil having a flat outer surface, said anvil attached to the press bed in an opposing relationship to said rocker;
• a portion of said rocker extending beyond at least one said saddle longitudinal end, said rocker end portion having a surface which defines two generally flat ledges parallel to the axis of said rocker and set at a predetermined angle with respect to one another and with respect to said rocker flat;
• a kicker block attached to said saddle end beyond which said rocker extends having a generally flat stop surface in interactive relationship with one said ledge at a predetermined forward rotation of said rocker in said saddle and with the other said ledge at a predetermined reverse rotation of said rocker in said saddle to limit the rotation of said rocker in said saddle between a predetermined initial position and a predetermined final position to thereby control the initial and final position of said flat and said lobes with respect to said anvil and with respect to the bendable sheet material.

In a press having a reciprocating ram opposing a bed on which a bendable sheet material having an upset skirt is placed, a rotary hemming tool comprising:

• a saddle attached to the ram facing the bed, said saddle having a surface penetrating extending between saddle longitudinal ends which defines a hemi-cylindrical groove cut along its length;
• rotatably disposed in said saddle groove, a generally cylindrical rocker having its cylindrical surface altered by a flat extending its length and by lobes at the transition from said flat to said cylindrical surface, said rocker lobes of lesser radius than the circumference of said rocker;
• a portion of said rocker extending beyond at least one said saddle longitudinal end, said rocker end portion having a surface which defines a generally flat first ledge parallel to the axis of said rocker and at a predetermined angle with respect to said flat portion of said rocker;
• a kicker block attached to said saddle end adjacent said saddle groove having a generally flat stop surface in interactive relationship with said first ledge at a predetermined forward rotation of said rocker in said saddle;
• means for preventing reverse rotation of said rocker beyond its initial radial position.