Tool and method for the manufacture of cans

摘要

For the manufacture of can bodies as they are needed for the manufacture of aerosol cans or beverage cans, a special tool 2 is provided which combines the manufacture of the cup as well as the transformation of the cup into a can body into a single tool 3. The process is based on preferably round metal sheets which are first drawn in a first draw-stretching step of the tool 2 into cups and then are draw-stretched in a second draw-stretch process, the further draw- and slide-down-stretch to form can bodies. The drawing arrangements are the same in both operating steps. The tools required therefore are simple sturdy tools providing for a simple sturdy manufacturing process.

主权项

1. A tool (2) for the manufacture of a can body carried by a transformation machine (1) comprising:
a lower tool part (3) operably affixed to and supported by the transformation machine (1), an upper tool part (4) operably supported to be linearly movable toward, and away from the lower tool part (3), the upper tool part (4) including a servo drive arrangement (5), the upper tool part (4) comprising a first extrusion punch (7) in operable arrangement with the servo drive arrangement (5), the upper tool part (4) operably arranged concentric to a center axis (6), a first downholder (9) in operable arrangement with the first extrusion punch (7), the upper tool part (4) comprising a second extrusion punch (8) operably arranged in the interior of the first extrusion punch (7) so as to be movable along the center axis (6), the lower tool part (3) having a planar surface (17) for supporting a planar metal sheet (18) to be formed finally into the can body, the lower tool part (3) having a stepped through-passage (19) therein concentric with the center axis (6), the stepped through-passage (19) including an annular step (20), the first extrusion punch (7) for operatively passing within the stepped through-passage (19) above the annular step (20), the second extrusion punch (8) for operatively passing within the stepped through-passage (19) below the annular step (20), the first downholder (9) in operative arrangement with the first extrusion punch (7) for initially applying a controlled force to the planar sheet (18) for forming a pre-can body cup from the planar metal sheet (18), the servo drive arrangement (5) which is operable selectively electronically switchable between a first operating mode and a second operating mode, the first operating mode of the servo drive arrangement (5) is a position controlled operation for detecting the position of the extrusion punch (7) and moving the extrusion punch (7) based on feedback of the detected position of the extrusion punch (7) in accordance with a predetermined travel distance-time curve for moving the first extrusion punch (7) in a coordinated manner with the second extrusion punch (8) above the annular step (20) until the first extrusion punch (7) reaches the annular step (20) and the second operating mode is a force controlled operation for controlling electronically the force applied by the first extrusion punch (7) to the pre-can body cup between the first extrusion punch (7) and the annular step (20) in a downhold function by detecting the force applied by the first extrusion punch (7) to the pre-can body cup for ensuring correspondence to a predetermined force or a predetermined force graph, the switching of the servo drive arrangement (5) from the first operating mode to the second operating mode is executed when the first extrusion punch (7) changes its function from a draw function to the downhold function at the annular step (20), the second extrusion punch (8) arranged coaxially with the first extrusion punch (7) for further drawing and stretching the pre-can body cup below the annular step (20) for forming the can body, and, the first extrusion punch (7) and the second extrusion punch (8) are driven to run in the same direction.