Document Type and Number:
Japanese Patent JPH0144617
Kind Code:
Y2
Application Number:
JP10703484U
Publication Date:
December 22, 1989
Filing Date:
July 13, 1984
Export Citation:
International Classes:
E21B1/26; E21B1/00; E21B21/00; (IPC1-7): E21C3/20; E21C7/02
Next Patent: JPH0144618