The rolling of threads and the cold working of the coat of round pieces.
A thread is created by shaping a work piece under tremendous force between the two rotating tools roller. With the penetration of the profiles of the roller tool in the surface of the work piece, the material is cold-pressed in the bottom of the rollers tools and is then wound until it reaches the nominal size.
Advantages of rolling of fillets are:
- significant increase of strength due to cold forming
- outstanding values of roughness on the thread flanks and bottom radius
- reduced notch sensitivity
- no interruption of the fibre direction as is the case in fillets cut
- high dimensional accuracy
- rational and rapid production
- extremely advantageous especially on large quantities
They can be used all the materials that:
- have at least one expansion of 6% and with tensile strength not exceeding 1300 N/mm2
- high-alloy steel, corrosion and acid-resistant
- special aluminium alloys.
- copper alloys
Can not be rolled materials:
- extremely fragile as MS58, cast gray iron, etc..
- extremely soft as lead