Early in the 90’s I developed two variations of re-configurable dies or molds. While the idea of re-configurable tooling was certainly not new, these concepts provided a unique approach.
Advances in this technology are ongoing even today. A relevant example being the DYNAPIXEL product developed by CIKONI GmbH. I have spoken at length with Dr. Farbod Nezami, Co-Founder and Managing Director at CIKONI, and am impressed with their application.
An excellent resource for those interested is the 2007 paper entitled “Reconfigurable Pin-Type Tooling: A Survey of Prior Art and Reduction to Practice” by Associate Professor Daniel Walczyk and Research Assistant Chris Munro in the Department of Mechanical, Aerospace & Nuclear Engineering at Rensselaer Polytechnic Institute – Troy, NY. (Professor Walczyk, Ph.D, PE is now Director of the Center of Automation Technologies and Systems at Rensselaer.) I have found this paper to contain extremely comprehensive research on the topic and have referred to it many times.
*Note: Differing core and cavity shapes shown in above image.
I designed and manufactured these tools for use in the rapid iteration of sheet metal parts, 5052 aluminum in this particular instance. The two die halves would be configured as cavity and core and used in a press (Ref. Fig. 1).
Fig. 1
In the scenario offering the greatest member density and thus highest surface resolution, the tools were composed of oval pointed set screws held in a hexagonal matrix. The common pitch of the screws allowed the adjacent neighbors of any individual to act as a nut.
Offsetting the cavity matrix from that of the core such that individual members align only with the void area of their counterpart, produced a smooth finish as the material yielded (Ref. Fig. 2).
Fig. 2
Additionally, press shut height was set such that material thickness was never pinched between cavity and core eliminating dimpling.
Shape generation of die surfaces was accomplished via a conventional CNC machining center. In each half, members were displaced (screwed) individually with the spindle using a hex key in a floating tap holder (Ref. Fig. 3 & 4). All controlled through standard G&M code programming generated from a matrix algorithm. The return to a flat surface accomplished by reversal of the program readies the tool for the next shape. Moderate surface geometries could be rendered in as little as 5 minutes on this particular tool.
Fig. 3
Fig. 4
In an alternative configuration, hydraulics were employed. Instead of screw threads, cylindrical shaft members with full radius ends were arranged in the same hexagonal matrix. Actuation of individual members occurred via small hydraulic cylinders attached to each. As a feedback loop for every cylinder was cost prohibitive, I came up with a system that used only one. Member cylinders were all plumbed to a single master cylinder containing the feedback loop thus forming a closed hydraulic system. As the master cylinder was displaced, valves for each cylinder in the matrix were closed based on the volumetric displacement required for their specific positioning (Ref. Fig. 5). As a result, the surface shape would “grow” from a flat surface in a single stroke of the master cylinder.
Fig. 5
