Threading method, rolling head, apparatus, module and production line for pipe thread, and products thereof

A method for rolling an external pipe thread, wherein the method is to perform thread forming rolling process on the outer surface of a hollow blank which have been rolled through a pre-forming rolling,

• wherein the pre-forming rolling refers to a process of rolling the outer surface of the hollow blank into a threaded cylindrical or a threaded conical surface or a threaded cylindrical conical mixing surface by a first rolling wheel group, and the first rolling wheel group comprises at least three circumferentially arranged first rolling wheels with pre-formed thread outer surfaces, and the external pipe thread forming rolling is performed by a second rolling wheel group including at least two circumferentially arranged second rolling wheels whose outer surface having an external pipe thread forming portion, and
• wherein a number of the first rolling wheels in the first rolling wheel group and a number of the second rolling wheels in the second rolling wheel group is odd-even different;
• and
• the pitch of the pre-formed thread is equal to the pitch of the thread on the external pipe thread forming portion, and the depth of the pre-formed thread is smaller than the depth of the thread on the external thread forming portion.

A process module for rolling an external pipe thread, comprising a first rolling head and a second rolling head, wherein the first rolling head comprises at least three circumferentially arranged first rolling wheels;

• the first rolling wheels are rolling wheels with pre-formed thread outer surfaces;
• and
• the second rolling head comprises at least two circumferentially arranged second rolling wheels having an external pipe thread forming portion;
• the second rolling wheels are rolling wheels with pre-formed thread outer surfaces;
• and
• a number of the first rolling wheels in the first rolling wheel group and a number of the second rolling wheels in the second rolling wheel group is odd-even different;
• and
• the pitch of the first rolling wheel thread is equal to the pitch of the thread on the second rolling wheel thread, and the depth of the first rolling wheel thread is smaller than the depth of the second rolling wheel thread.