Precision tubes for mechanical machining – HPZ type
Standards and steel grades.
Precision tubes for mechanical machining are produced by the cold drawn process. The rolled seamless tubes are used as the semi-finished product. HPZ type precision tubes are used as the semi-finished product to produce the hydraulic cylinders. They are destined to have the inside surface machined by honing or stripping and subsequent rolling. Precision tubes for mechanical machining are manufactured from carbon and alloyed steel. Overview of dimensional standards and technical and delivery conditions for mechanical tubes are presented in a separate overview.
a separate overview . Steel is produced in the electric arc furnace and it is fully killed. Other steel grades may be delivered upon agreement.
Condition of delivery and thermal treatment of hydraulic cylinder tubesThe tubes are delivered as cold drawn and annealed to relieve the stress BKS (+SR). Other delivery conditions are possible upon agreement. Overview of other conditions may be found here.
Length of hydraulic cylinder tubes- manufactured length of precision tubes in the range of 3 to 6 meters
- maximum precise length 6 meters
Tolerances of hydraulic cylinder tubesTolerances of the outside diameter (OD) HPZ tubes meet the appropriate dimensional table standards. Tolerances values of the inside diameter (ID) are presented in the table. Tolerance of the wall thickness is -/+ 7.5% of the wall thickness. HPZ tubes eccentricity is included in the wall thickness tolerance.
Straightness of hydraulic cylinder tubes1 mm / m (1 : 1 000) measured on the outside surface.
Condition of the precision tube surface for mechanical machiningAccording to the EN 10305-1 directives the precision tubes have the outside surface smooth.
Ends of the hydraulic cylinder tubesEnds of the tubes are square to the longitudinal axis of the tubes. Upon agreement the tubes may be capped with plastic caps.
Marking of the hydraulic cylinder tubesThe tubes are marked along the length of the tube where the following pieces of information are used: manufacturers’ logo, dimension (OD x ID), steel, heat number and the number of standard or other data as per the customers’ request.
Surface protection of the hydraulic cylinder tubesThe surface of the tubes is oiled.
Testing of precision tubes for mechanical machiningSelection of the tests is either according to standards or upon agreement with customer: chemical analysis, tensile test, dimensional test, visual inspection and nondestructive testing (eddy current). Other tests are possible upon agreement.
Certificates for hydraulic cylinder tubesAccording to standards: EN 10 204 - 3.1 or DIN 50049 - 3.1.B