(19)
(11) EP 0 220 147 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
17.11.1988 Bulletin 1988/46

(43) Date of publication A2:
29.04.1987 Bulletin 1987/18

(21) Application number: 86850341

(22) Date of filing: 08.10.1986
(84) Designated Contracting States:
AT DE FR GB SE

(30) Priority: 17.10.1985 SE 8504842

(71) Applicant: Santrade Ltd.
 ()

(72) Inventor:
  • Liljekvist, Sören
     ()

   


(54) Thread coupling for percussion drilling


(57) A thread coupling for drill rods for percussion rock drilling comprising a male thread (15) and a co-operating female thread (12). The threads (12, 15) are designed internally in such a way that an essentially unchanged contact surface is maintained between the contact shoulders (16) of the threads adjacent to the thread clearance of the female thread (12) or the thread outlet of the male thread (15).






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