PTAB

IPR2018-01415

Berkenhoff GmbH v. Seong Ki Chul

Log In
Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Electrode Wire for Electro-Discharge Machining and Method for Manufacturing the Same
  • Brief Description: The ’872 patent discloses an electrode wire for electro-discharge machining (EDM) and a method for its manufacture. The invention describes a wire with a metal core, a first alloy layer, and a second alloy layer, where cracks and grains are formed on the surface by "forcibly curving or twisting" the wire to erupt core material and improve machining performance.

3. Grounds for Unpatentability

Ground 1: Obviousness over Tomalin and Nishioka - Claims 1-13 and 15 are obvious over Tomalin in view of Nishioka.

  • Prior Art Relied Upon: Tomalin (Patent 5,945,010) and Nishioka (Patent 3,326,025).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Tomalin disclosed all elements of the challenged claims except for the specific step of forming cracks by "twisting the wire with a plurality of rollers." Tomalin taught an EDM wire with a core, a first (gamma phase) and second (epsilon phase) alloy layer formed through diffusion, and cracks in these layers that allow core material to erupt and form grains on the surface. Petitioner asserted that Nishioka supplied the missing element by teaching a wire drawing apparatus that uses "zig-zag bending" via a plurality of parallel rollers, which it contended was a form of twisting well-known in the art.
    • Motivation to Combine: A POSITA would combine these references as a matter of routine practice. Tomalin taught creating cracks by drawing a wire but was silent on the specific drawing technique. Nishioka disclosed a well-known technique for drawing wire using a bending/twisting motion with rollers. Therefore, a POSITA would have been motivated to use the known drawing technique from Nishioka to manufacture the wire disclosed in Tomalin, as it was a simple substitution of one known method for another to achieve the predictable result of creating cracks.
    • Expectation of Success: A POSITA would have had a high expectation of success. It was known that the brittle, high-zinc-content alloy layers described in Tomalin would crack when subjected to the mechanical stress of a bending process like that taught by Nishioka. The combination would predictably yield a wire with the desired surface cracks.

Ground 2: Obviousness over Tomalin, Groos, and Grandy - Claims 1-13 and 15 are obvious over Tomalin in view of Groos and Grandy.

  • Prior Art Relied Upon: Tomalin (Patent 5,945,010), Groos (Patent 4,766,280), and Grandy (Patent 3,677,309).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground was presented as an alternative to Ground 1, addressing a potential interpretation that the claimed "twisting" requires a rotational or torsional motion, rather than Nishioka’s bending. Petitioner again relied on Tomalin for the base wire structure with its core and cracked alloy layers. Groos was cited for teaching the benefits of torsionally twisting an EDM wire to create helical edges that improve flushing of eroded material. While Groos taught twisting by clamping one end and rotating the other, Grandy was cited for disclosing a method of twisting wire continuously using rollers.
    • Motivation to Combine: A POSITA would combine these references to solve the known problem of improving flushing efficiency in EDM processes. Tomalin taught that its cracked surface achieved "enhanced flushing." Groos taught that its twisted wire with helical edges was "suited to quickly and safely remove the eroded material." A POSITA would be motivated to apply the twisting technique of Groos to the cracked-surface wire of Tomalin to combine their respective flushing benefits. Furthermore, a POSITA would substitute Grandy's roller-based twisting method for Groos's clamp-based method to enable a more efficient, continuous manufacturing process.
    • Expectation of Success: The outcome of the combination was predictable. Applying a known twisting process (Groos, implemented with Grandy's rollers) to a known EDM wire structure (Tomalin) would be expected to produce a wire having both a cracked surface and helical edges, thereby predictably enhancing performance.

  • Additional Grounds: Petitioner asserted additional obviousness challenges (Grounds 2 and 4) that added the ASM Handbook to the primary combinations to explicitly teach the tensile strength and elongation properties recited in method claims 9-13 and 15. The Handbook was cited as a standard industry reference providing known material properties for the brass alloys used in the primary references.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-13 and 15 of the ’872 patent as unpatentable.