CPC Subgroup
B21H 3/08 internal screw-threads
Full Title
Making helical bodies or bodies having parts of helical shape (helical gears B21H5/00; forming tubes or tube walls into helical shape B21D11/06, B21D15/04) > internal screw-threads
B21H 3/08 Making helical bodies or bodies having parts of helical shape (helical gears B21H5/00; forming tubes or tube walls into helical shape B21D11/06, B21D15/04) > internal screw-threads