DIFF Subgroup
B21H 3/08 internal screw-threads
Introduced: September 1968
Full Title
Full titles differ between systems:
IPC:
Making helical bodies or bodies having parts of helical shape > internal screw-threads
CPC:
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
No child classifications to compare. This is a leaf node in both IPC and CPC.