US 6,077,171 · Granted 2000-06-20
The Tungsten Weight Patent That Let Golfers Fine-Tune Their Swing
Yonex figured out how to make iron golf club heads lighter by using titanium, then stuffed heavy tungsten weights into precise holes to move the club's sweet spot exactly where each golfer needs it. It's like tuning a musical instrument, but for your golf game.
The plain-English version
What it protects
The claim covers an iron golf club head made from lightweight titanium with a cavity in the back and strategically placed holes drilled parallel to the club's sole. What's protected here is the specific method of inserting heavy tungsten or tungsten-alloy weight members into those holes to adjust where the club's center of gravity sits, with the total weight of those inserts capped at 40 percent of the head's total weight.
Why it matters
This patent gives Yonex a way to offer golfers precise control over their club's performance characteristics without making the head heavier overall. By combining a light titanium body with strategic tungsten placement, manufacturers can dial in the exact center-of-gravity location that suits different swing styles—something competitors can't easily copy without infringing on the specific geometry and material combination protected here.
Real-world use
Every time a golfer picks up a modern iron club and feels the subtle weight distribution that makes their swing feel 'right,' they're often experiencing a geometry engineered around principles like these tungsten-weight adjustments.
Original USPTO abstract
An iron golf club head comprised of a head body 10 made of light metal such as titanium and containing a plurality of weight members 16. The head body 10 includes a front surface 13, a rear surface 13a, a cavity 12 disposed at the rear surface 13a, and a plurality of holes 15 disposed in the head body 10 at the rear surface 13a between a lower side wall 12b of the cavity 12 and a sole 14 of the head body 10 at predetermined intervals between a toe part 17 and a heel part 18. The center axis of each hole 15 is oriented substantially parallel to the sole 14 of the head body 10. The weight members 16 are press-inserted into the holes 15 in a direction going toward the front surface 13 of the head body 10 to a predetermined depth. Each weight member 16 is made of a material having a heavier specific weight than the light metal used for the aforesaid head body 10. Tungsten or tungsten alloy can be used as the material for the weight members 16. The combined weight of the weight members 16 does not exceed forty percent of the weight of the entire head.
Patent details
- Publication number
- US 6,077,171
- Filing date
- 1998-11-23
- Grant date
- 2000-06-20
- Assignee
- Yonex Kabushiki Kaisha
- Inventor(s)
- YONEYAMA; MINORU
- CPC class
- A63B53/04
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