Mold making process

A process for making from a mold blank a metal mold having a contoured surface corresponding to the outer surface of a product to be molded and having a plurality of finished projections on the contoured surface having sides extending from the contoured surface, comprising the steps of,

• generating a three-dimensional representation of the contoured surface and the finished projections,
• machining an electrode for electric discharge machining apparatus having slots of greater dimensions than the finished projections for forming initial projections of greater dimensions than the finished projections,
• mounting the electrode and the mold blank in the electric discharge machining apparatus,
• generating an electric discharge between the electrode and the mold blank,
• effecting relative motion between the electrode and the mold blank to achieve machining engagement therebetween for forming the initial projections, and
• relatively orbiting the electrode and the mold segment blank for machining the initial projections to the orientation and configuration of the finished projections and effecting finishing on the surfaces thereof.

A process for making from a mold segment blank a metal tire mold having a tread contour surface corresponding to the outer circumference of a tire to be molded and having a plurality of finished projections on the tire tread contour surface having sides oriented substantially normal to the tire tread contour thereat and arranged in a plurality of individual subsystems having geometries that repeat over the outer circumference of the tire, comprising the steps of,

• generating a three-dimensional representation of the tread contour surface and the finished projections,
• determining an electrode geometry for the individual subsystems which when machined in an electrode for electric discharge machining apparatus forms the individual subsystems on the surfaces of the mold segment blank substantially within preselected surface dimensional tolerances for each individual subsystem,
• determining an orbit pattern for the individual subsystems in which the electrode and the mold blank are moved relative to each other during machining,
• combining the electrode geometry for selected of the individual subsystems into a combination electrode geometry,
• determining an electrode geometry for the combination of selected individual subsystems which when machined in the electrode for electric discharge machining apparatus forms the individual subsystems on the surfaces of the mold segment blank substantially within the preselected surface dimensional tolerances for each selected individual subsystem,
• determining an orbit pattern for the combination of selected individual subsystems with which the electrode and the mold blank are moved relative to each other during machining,
• machining an electrode having the electrode geometry determined for the combination of selected individual subsystems,
• mounting the electrode and the mold segment blank in the electric discharge machining apparatus,
• generating an electric discharge between the electrode and the mold segment blank, and
• relatively orbiting the electrode and the mold segment blank in said orbit pattern for said combination of selected individual subsystems for forming the finished projections and effecting finishing on the surfaces thereof substantially within said preselected surface dimensional tolerances for each individual subsystem.

A process for making an electrode for electric discharge machining of a mold segment blank into a metal tire mold having a tread contour surface corresponding to the outer circumference of a tire to be molded and having a plurality of finished projections on the tire tread contour surface arranged in a plurality of individual subsystems having geometries that repeat over the outer circumference of the tire, comprising the steps of,

• generating a three-dimensional representation of the tread contour surface and the finished projections,
• determining an electrode geometry for the individual subsystems which when machined in an electrode for electric discharge machining forms the individual subsystems on the surfaces of the mold segment blank substantially within preselected surface dimensional tolerances for each individual subsystem,
• determining an orbit pattern for the individual subsystems in which the electrode and the mold blank are moved relative to each other during machining,
• combining the electrode geometry for selected of the individual subsystems into a combination electrode geometry,
• determining an electrode geometry for the combination of selected individual subsystems which when machined in the electrode for electric discharge machining forms the individual subsystems on the surfaces of the mold segment blank substantially within the preselected surface dimensional tolerances for each selected individual subsystem,
• determining an orbit pattern for the combination of selected individual subsystems with which the electrode and the mold blank are moved relative to each other during machining,
• machining an electrode having the electrode geometry determined for the combination of selected individual subsystems, and
• relatively orbiting the electrode and the mold segment blank in the orbit pattern determined for the combination of selected individual subsystems for forming the finished projections and effecting finishing on the surfaces thereof substantially within the preselected surface dimensional tolerances for each individual subsystem.