MECHANICAL EXPANDER CONE

• Main Authors: AOKI HIROMICHI, ONO KEIICHIRO
• Format: Patent
• Language: English
• Published: 04.12.1989
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; PERFORMING OPERATIONS; PUNCHING METAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TRANSPORTING; WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS ORPROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL

PURPOSE:To improve seizure resistance and impact resistance by forming a hardened layer of a specified depth through nitriding treatment on a surface layer after steel is formed as a base material. CONSTITUTION:The steel used as a base material for an expander cone is drastically excellent in strength and is not broken down though the draft force in expanding a tube increases remarkably. On one hand, a hardened layer of 0.15-1.5mm depth is formed by nitriding treatment to elevate its hardness and give lubricating properties. Consequently, seizure resistance and wear resistance are improved and, further, low friction characteristics, too, are secured. Besides, since compressive residual stress remains on the nitride layer, a fatigue strength of about 1.1 times that of the base material can be obtained.