Yan Zhao

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Hubei Province, CN

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Patents Grantslast 30 patents

Information Patent Grant
Roller bit with a journal pin offset from the central axis thereof
- Patent number 7,299,887
- Issue date Nov 27, 2007
- Kingdream Public Ltd. Co.
- Xuezhong Liu
- E21 - EARTH DRILLING MINING

Patents Applicationslast 30 patents

Information Patent Application
Roller bit with a journal pin offset from the central axis thereof
- Publication number 20050252692
- Publication date Nov 17, 2005
- Xuezhong Liu
- E21 - EARTH DRILLING MINING