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Expired Canadian patentCanada

Elliptical thread design

CA 1316301 C · Owner: Chuang, Jo-Yu · Inventors: Chuang, Jo-Yu

CIPO record

Overview

Drawings and full text

Its claims, description and drawings are in the Canadian Patents Database.

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Abstract From the Canadian patent

A screw structure (10) is provided for male and female threads (14) having at least one thread (14) extending helically along a cylindrical support (12) member in spaced thread turns. A root portion (22) extends between adjacent thread (14) turns and has a curvature defined by a portion of an ellipse (24) for providing improved stress reduction during periods of severe loading.

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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.

Why it's free to use

  • Granted April 20, 1993. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended April 20, 2010.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledJanuary 10, 1989
GrantedApril 20, 1993
Term endedApril 20, 2010
Patent numberCA 1316301 C
Classification (IPC)E21B17/04 +2 more

Timeline

Timeline From CIPO dates

1990199319961999200220052008Application filedJan 10, 1989Patent grantedApril 20, 1993Term endedApril 20, 2010

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.