Stretch Forming Processes
Stretch Forming routings include the following processes:
• 3-Roll Bending (from the Sheet Metal process group): stock is temporarily coiled in order to enable more efficient use of space during heat treatment and cold storage (see below).
• Solution (from the Heat Treatment process group): the coiled stock is annealed in order to decrease its tensile yield strength and ultimate tensile strength, in preparation for stretching.
• Cold Storage: the coiled stock is cooled in order to maintain the post-annealed material properties.
• Stretch Form: this process includes operations associated with the stretch forming machine, including cleaning and lubricating the tool, loading the blank onto the machine (and unloading it from the machine), inspecting the blank, pre-stretching it if necessary, and performing either transverse or longitudinal stretching (see
Transverse and Longitudinal Stretch Forming).
• Shear (from the Sheet Metal process group): the formed part is trimmed in order to remove the addenda, which are added to the blank in order to provide material for the machine jaws to grip.
• Bench Operation: this process includes manual operations that are performed after the part is removed from the stretch forming machine. The operations are performed in a separate work area. They include cleaning and inspection, as well as hand forming of any curved bends.
• Router: near-net-shape trimming is performed using a hand router and a template.
• Machining: the part is routed to the 5-Axis Mill in the Machining process group for final-shape profile trimming (as well as hole creation, if necessary). Parts can also be manually routed to Chemical Milling for selective thickness reduction--in the Routing Selection dialog, expand the Machining node, and select Chemical Milling.
The sequence of processes consisting of Solution, Cold Storage, and Stretch Form can be performed one or more times before moving on to the Shear process. A setup option controls the number of occurrences of the sequence on a part by part basis. A cost model variable controls the default number of occurrences (1 in starting point VPEs).