STONES OPEN FORUM Aberdeen 2009-12-06. © World Curling Federation2 | STONES 4A= 64+2stones WCF 24001? to WCF 24066? 4B= 64+2 stones WCF 24101? to WCF

STONES

OPEN FORUMAberdeen 2009-12-06

© World Curling Federation2 |

STONES

4A= 64+2stones WCF 24001? to WCF 24066?

4B= 64+2 stones WCF 24101? to WCF 24166?

5A= 80+2 stones WCF 25001A to WCF 25082A

5B= 80+2 stones WCF 25101? to WCF 25182?

6A= 96+2 stones WCF 26001? to WCF 26098?

New WCF stone consignments(384 stones + 10 spares)

All these stones have been printed and measured and the differences in measurements demand adjustments to the running bands


STONES

running band inside diameterrunning band widthrunning band areaweight

80+2 stonesNew stone consignment 5A

4.5mm (120.6 to 125.1)1.96mm (5.36 to 7.32)8.46cm2 (21.54 to 30.00) 0.44kg (18.35 to 18.79)

1.4mm (122.4 to 123.8)0.15mm (5.53 to 5.68)0.62cm2 (22.35 to 23.00) 0.22kg (18.20 to 18.42)

Important measurements

for good stone quality

Old stone numbers were WCF 30xx, 32xx and 35xx (Blue Hone inserts)

New stone numbers are WCF 25001 to 25082

Old consignment New consignmentDifferences in:

The “real” running band and the roughness are not yet possible to measure in a safe way


R&D STONES

Today


R&D STONES


R&D STONES

Leif ÖhmanLeif Öhman

Tomorrow(today)


Ny curlingsten Uppsala

R&D STONES



R&D STONES


Running band roughness


R&D STONES

Testing roughness meter


R&D STONES

Stone standing on hard surface (maybe hard ice)



R&D STONES

Stone standing on softer surface (maybe soft ice)



R&D STONE

Stone standing on even softer surface


© World Curling Federation13 |Leif ÖhmanLeif Öhman

R&D STONES

Stone standing on very soft surface

Similar result as using rolling pin, but is this the stone surface towards the ice?


R&D STONES

We need to develop a method to compare running bands and how they stands on ice

We also need to find a method to measure the surface structure (scratches)

When we know that we don’t need to match stones on ice any more

The knowledge about the different parts involved is not sufficient yet



STONES

Matching stones


STONES

Stone thrower 8 stones (example)

To throw stones on ice is still the best matching method


R&D STONES

Other matching methods possible, but not developed

–Camera to see the stone movement (X;Y)

–Using total station to see the movement in x;y direction

–Measure the speed in two positions and calculate the friction coefficient to match the speed


Using cameras for matching the curling stones

R&D a camera method


Camera

R&D a camera method


R&D a camera method

•Automatic stone tracking•Records the position of the stones in the image•Translates to real world coordinates (X;Y)

Camera


(x,y)

R&D a camera method


Fitted according to eq(7)+eq(13)

0

0.05

0.1

0.15

0.2

0.25

0.3

16 18 20 22 24 26 28 30

Good precision

Far away, precision 3 cm

Estimated lambda = 2.49


R&D automatic total station

Automatically measuring the stone movement with total station


R&D Automatic total station

Result of the measuring


STONES

Rubbing the running band?

Greenacres Curling Rink has played more than 3000 games with their stones and the movement is still 4 feet and 24 seconds without rubbing

“Crystal Ice” for high level competitions demands special running band rubbing

Should normal club stones be rubbed?


R&D STONES

What happens in the long term when rubbing the stones?

A scratch in Granite

A scratch in Calcite


Hair

A hair is approx. 50 um thick = 500-50 000 ggr thicker than the water film

On the top of all ice crystals there is an extreme thin water-like film

As colder as thinner

Ice Crystal

Thin watery film app. 0,002-0,1 um

R&D ICE

This gives wet friction


R&D ICE

Wet friction is a prerequisite to have a curling stone to curl.

But why will a curling stone curl?


R&D ICE

On wet friction surfaces the friction coefficient changes with the speed and the temperature


Sto

ne

spee

d

Curl

Sto

ne

curl

Sto

ne

curl

Sto

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spee

d

R&D STONE CURL


Res

ult

ing

Sto

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Sp

eed

Curl

Sto

ne

curl

R&D STONE CURL

Res

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ing

Sto

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Sp

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Sto

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curl

Documents

STONES OPEN FORUM Aberdeen 2009-12-06. © World Curling Federation2 | STONES 4A= 64+2stones WCF 24001? to WCF 24066? 4B= 64+2 stones WCF 24101? to WCF