Precision tubes for production of bearings
Standards and steel grades,
Precision tubes for production of bearings use the cold drawing process. Rolled seamless tubes are used as the semi-finished product. Overview of dimensional standards and technical-delivery conditions of the tubes for hydraulic and pneumatic circles are presented in a separate overview .
separate overview. Upon agreement it is possible to deliver other types of steel.
Delivery condition and thermal treatment of precision tubes for bearing productionBearing tubes are delivered are delivered in the GKZ + K +G condition, i.e. annealed to globular carbides – cold drawn – soft annealed. Overview of other thermal treatment conditions may be found here.
Length of bearing tubeslength 3 000 mm with tolerance +/- 500 mm
Tolerances of tubes for bearing production
|outside diameter||D < 50 mm||0|
|outside diameter||D > 50 mm||0|
|wall thickness||-/+ 7,5 % (after agreement 5 -/+ %) of the wall thickness|
Straightness of precision tubes for bearing production1 mm / m (1 : 1 000) measured on the outside surface, maximum 2.5 mm / 3000 mm.
Ends of the bearing tubesTubes have its ends smooth, plain square cut ends, one beveled 0.5 to 4 00 x 45°.
Testing of bearing tubesTesting is done according to DIN 17 230.
Marking of bearing tubesBundles of tubes are marked with label.
Surface protection of bearing tubesSurface of the tubes is oiled.
Certificates for bearing tubesAccording to DIN 50049 - EN 10204 - 3.1.B.
Steel hardness for bearing tubesAfter the soft annealing the hardness ranges is 174 – 220 HB. Hardness value dispersion along the length of the tube is 15 HB maximum. Minimum hardness according to the hardness test is 61 HRc.
Surface condition of bearing tubesTubes are delivered with after its surface was soft annealed. Maximum depth of defects is 0,25 mm and it includes decarbonizing.
Microstructure of bearing tubesTesting procedures according to SEP 1520: carbide sizes 2.1 – 2.3, lamellar pearlite 3.0, carbide net 5.2, carbide line spacing (max 6.3 – continuous, max 7.3 – released).
MicropurityTested according to DIN 50602. Total value of oxide and sulphur micropurity K3 <= 10.
DemagnetizingResidual magnetism 10 Oe maximum.
The tubes also may be delivered as hot rolled. It is also possible to deliver bearing tubes according to STN EN ISO 683-17. It is annealed and automated steel that it is destined for hot treatment, part 17: steel for roller bearings.