US 5,451,056 · Granted 1995-09-19
The Foam-Filled Golf Club Head That Made Off-Center Hits Count
Imagine a hollow metal golf club head packed with foam that's engineered so you get a good shot even when you don't hit the sweet spot dead-center. The design creates invisible zones on the clubface where the ball responds almost the same way no matter where it lands, making golf more forgiving for everyday players.
The plain-English version
What it protects
The claim covers a hollow metal golf club head filled with foam material, where the weight distribution is precisely calculated to create an expanded 'sweet spot' at the geometric center of the face. What's protected here is the specific geometry and foam-filling method that produces multiple elliptical force zones on the striking face—meaning balls hit anywhere within those zones deliver nearly identical impact forces and results.
Why it matters
This patent represented a major shift in golf club design toward 'game improvement' clubs that reward casual players. By engineering a larger effective sweet spot through foam filling and weight distribution, manufacturers could make clubs that deliver consistent performance on mishits. This approach became industry standard and helped drive the modern golf equipment market toward accessibility, directly competing with tour-grade clubs that only rewarded perfect strikes.
Real-world use
When you pick up a modern metal wood at a golf range, the hollow core you hear when you tap it and the consistent distance you get even on off-center swings are direct results of this patent's technology.
Original USPTO abstract
A metal wood type golf club head has a substantially hollow metallic body defining a bottom sole extending between a toe and heel, a top wall or crown, a ball striking face having parallel horizontal grooves, and a hosel formed at the heel to receive a shaft. The interior of the hollow body is filled with a foam material. The weight of the metallic body is distributed to establish an optimum impact point or sweet spot at substantially the geometric center of the ball striking face, and further establishes a plurality of substantially elliptical force lines on the face concentric with the sweet spot. Each elliptical force line represents a locus of points operative to impart substantially equal impact forces to a ball struck at a point on the corresponding elliptical force line, the major axis of the concentric elliptical force lines passing generally through the sweet spot substantially parallel to the grooves. Golf club heads in accordance with the present invention effectively provide larger sweet spots on the hitting faces of the heads so as to produce results from off-center shots that more closely approach the results produced when balls are struck at the sweet spot on the club head face.
Patent details
- Publication number
- US 5,451,056
- Filing date
- 1994-08-11
- Grant date
- 1995-09-19
- Assignee
- Hillerich And Bradsby Co., Inc.
- Inventor(s)
- MANNING; GEORGE E.
- CPC class
- A63B53/04
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