Page 30 - MetalForming July 2011

Tooling Technology
Better Die Life for
Stamper
T15 tungsten-vanadium powder-metallurgy tool steels traditionally gain favor for
high-speed high-performance cutting tools. Here, a wiper- blade manufacturer engages the PM tool steel for stamping prehardened spring steel.
BY BRAD F. KUVIN, EDITOR
I’ve noticed them, and maybe you have too—what the automotive industry refers to as “beam blades,” relatively newly designed
steel-blade wipers that distribute all of the force on the wiper arm to the middle of the unit. The curved spring-steel blade, says manufac- turer Trico Products, is bonded to the length of the rubber wiping blade. The design creates
infinite pressure points and continuous pres- sure across the length of the wiper. Compared to the conventional wiper design most of us grew up with (a pivoting U-shaped shaft accompanied by smaller pivoting shafts that held the rubber blade via two springy steel strips), windshield cleaning and durability is
Trico Products rollforms and stamps blades for its beam-style windshield wipers from prehardened spring steel.
A pair of small-bed stamping presses pierces and cuts-to-length rollformed shapes to fabricate the spring-steel beam blades. Tooling (shown here) is of Erasteel ASP 2015 powdered-metal high-speed steel, machined from 2.5-in.-thick blocks, heattreat- ed to Rc 63-64 and wire-cut to final dimensions.
vastly improved.
All of this benefit to the consumer does not come easy at
Trico Products, however. To achieve the properties needed in the beam blade, the firm must fabricate the blades from pre- hardened spring steel—no simple task. Typically, spring steels are supplied in the annealed condition for forming; hardened strip is more suitable for flat components.
28 MetalForming/July 2011
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Spring-Steel