Produse – Țevi pentru pistoane

ARTROM STEEL TUBES, it is a producer of steel tubes and pipes with 30 years of experience in producing and selling worldwide tubes mainly for industrial applications. The tubes production is integrated with our steel melting and billet casting from Resita performed under a common integrated management system and using up-to date technology the oldest steel producer from Romania.

Focused in production of seamless hot and cold finished tubes for mechanical applications, ARTROM STEEL TUBES has over 20 years of experience in production of Cold precision tubes suitable for Inside Skiving and Roller Burnishing (HPZ), being a major supplier for companies performing skiving operation as well for important companies producing Hydraulic Cylinders and Equipment.

Volumes for cold precision tubes for hydraulic cylinders have today a significant share in the total output of our cold finished production capacity.

ARTROM STEEL TUBES decides to develop cold finished product range in order to be closer to hydrau-lic cylinders producers by adding to the offer Inside Skived and Roller Burnished (SRB) tubes in lengths till 12 m. The state-of-the-art equipment special developed for this application and the partnership with one of the world most experienced producer for SRB tools is the premise for a high commitment for quality and flexibility.

The advantages ARTROM STEEL TUBES is offering to the customers are:

• Fully integrated and controlled process from steel melting till final machining of the tubes
• High expertise in offering and developing steel grades with characteristics for most demanding applications
• Quick response, flexibility and full customer care and services  Better cost control and optimization

• Production of hydraulic cylinders.

Hydra ArtH xxx OD x ID / Hydra ArtH xxx OD x ID –IFR

Hydra is the Artrom Steel Tubes classification of Cold drawn inside skived and roller burnished (SRB) tubes.
Art H xxx is the grade identification, xxx being the minimum granted yield point in Mpa.
OD, ID are outside and inside diameters nominal values.
IFR – Improved Fatigue Resistance – is an optional finishing which increase the Fatigue resistance on cycling stress specific for hydraulic cylinders use.

• Manufactured from steel billets produced by EAF process using fine grain practice and advanced cleaning procedures.
• Seamless hot rolled hollows are obtained with controlled concentricity on an ASSEL rolling line and then drawn to precision tubes with significant cross-section reduction improving the geometry and strengthens of the tubes. The cold deformed tubes are then Inside skived and roller burnished (SRB) using state of the art equipment and tools supplied by well-known producers with extensive expertise for these processes.
• Tubes with IFR (Improved Fatigue Resistance) are tested with high sensitivity ultrasonic meth-ods and additionally machined on outside surface using a center-less grinding process in order to remove any surface imperfection which can be potential fatigue cracking sources.
• Adequate steel chemistry as well as suitable heat treatments performed before and after cold working are used in order to obtain the mechanical properties for HYDRA ART grades described in Paragraph 6.
• The last heat treatment before delivery is listed for each grade:
  • +SR – Stress relieved
  • +N – Normalized
• Selection of the tests for HYDRA ART precision tubes:
  • Mandatory according to standards: Chemical analysis, Charpy test, Tensile test, Dimen-sional inspection, Visual inspection, Roughness measurement, NDT as per Paragraph 8;
  • Upon agreement with customer: NDT for other grades than standard offered, Flattening test or drift expanding test.

Size program according to Tab. 1. Other sizes can be produced by agreement but this can be subject of minimum ordered quantities or other commitments.

Size tolerances:

• Outside Diameter (OD) in accordance with EN 10305-1.
• Inside Diameter (ID) in accordance with ISO H8 – EN ISO 286-2, Ra – 0.3 µm or better (please see Tab. 1).

Note: On request, OD can be supplied only on agreed positive tolerances suitable for future machining (for example for telescopic cylinders). For such purpose the tubes can be pre-machined using a centerless grinding process, the final OD value and OD variation being necessary to be agreed.

Straightness: max 0.5 mm/1000 mm.

• Total deviation for tubes with length 6 m: max. 3.5 mm/length.
• Total deviation for tubes with length > 6 m: for each meter over 6 m the tolerance must be increased by 0.5 mm.

Roundness and eccentricity:

• OD and ID roundness deviation shall be within the limits of the OD and ID tolerances.
• Eccentricity shall be maximum 5%.
• Eccentricity calculated by formula:
  

Where Wt max, Wt min are maximum and minimum measured wall thickness in same crosssection.

The tubes are cold drawn having OD machined by center-less grinding to final piston rod size plus an agreed small over metal suitable for last grinding operation before chroming.

Final surface finish, Ra: 0.40 µm or better.
Straightness: max 0.35 mm/1000mm.
The tubes are suitable for chroming.

Note:

1. For grade showing sulfur content up to 0.020%, the sulfur can be added at manufacturer discretion to support machinability. The sulfur will be controlled added after a deep desulfurization.
2. Ceq is calculated by formula : Ceq= C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15
3. For grades ART H460, ART H620, ART H690 at manufacturer’s discretion the elements Nb, Ti and V can be added in order to obtain fine grain structure. The sum of these elements will be maximum 0.20%.
4. Steel grade ART H460 is fully comply also with EN 10216-3- P460NH.
5. Other chemical elements such Cr, Mo, Ni, Al, Cu not included here will be reported in MTR.

*Transversal impact test is possible for the sizes where standard test specimens can be machined from nominal wall.

Impact test values are the minimum granted average absorbed energy for 10×10 mm specimen with Vnotch.

The following impact test options can be provided:

• Option 1 – Longitudinal impact test: 40J and 27J transversal at – 40˚C
• Option 2 – Transversal impact test: 27J at – 20˚C
• Option 3 – Longitudinal impact test: 40J at – 50˚C

Upon request other values/temperatures for impact test can be agreed.

SRB tubes (before ID machining) and Piston Rod tubes (before OD grinding) are Non-destructive tested as follows:

• SRB tubes, grades ART H355, ART H450, ART H460, ART H525, ART H560 and all grades for piston rods tubes are UT tested, if Option 4 is selected.
• All IFR (Improved Fatigue Resistance) SRB tubes and all grades ART H620, ART H690 are full length Ultrasonic tested, using as reference standard notch disposed in longitudinal and transversal direction, on both External and Internal surface, 3 % Wt depth (with a minimum 0.20 mm), notch length maximum 25 mm, notch width maximum 0.50 mm.

Option 4 – full length Ultrasonic testing, using as reference standard notch disposed in longitudinal and transversal direction, on both External and Internal surface, 3 % Wt depth (with a minimum 0.20 mm), notch length maximum 25 mm, notch width maximum 0.50 mm.

The SRB or Piston Rod tubes having indications over the acceptance level are dressed and re-inspected.  The dressed area shall conform to specifications tolerances, contrary the tubes are rejected.

• Square cut to the longitudinal axis of the tubes with a slight bevel on outside surface.
• Protected with plastic caps.

• Minimum and maximum manufacturing lengths according to Table 1. Usually, the tubes shall be supplied in random lengths within 2 m variation.
• As an option fix lengths or multiple of fix length are available with cutting tolerance of -0/100 mm as well as cut to length pieces in range 0.4 – 4 m, cutting tolerance of -0/+3 mm.

SRB Tubes:
Inside and outside surface oiled by immersion in corrosion preventive oil in order to ensure temporary protection against corrosion during about 6 months storage in covered area, out of excessive humidity and/or direct water contact.

Piston Rods Tubes:
Unprotected for last grinding operation before chroming

Continuous marking along the length of the tube with following information: manufacturer’s logo, dimension (OD x ID), steel grade, heat number and the number of standard or other data as per the customers’ request.

Mill test reports are issued to customer requirements. Usually it comply with EN 10204 – 3.1