David Shirley

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Cheltenham, GB

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Patents Grantslast 30 patents

Information Patent Grant
Rotary drill bits
- Patent number 4,720,371
- Issue date Jan 19, 1988
- NL Petroleum Products Limited
- David Shirley
- B22 - CASTING POWDER METALLURGY
Information Patent Grant
Rotary drill bits
- Patent number 4,700,790
- Issue date Oct 20, 1987
- NL Petroleum Products Limited
- David Shirley
- E21 - EARTH DRILLING MINING