Process for manufacturing a circular saw blade and circular saw blade made thereby

A process for the manufacture of a circular saw blade by gluing together at least two congruent metal blades of an iron-based alloy, comprising, in the given order:

• providing at least two circular-saw-shaped metal blades cut thermally from heat-treated sheet material of iron-based alloy which comprises, besides iron and incidental impurities, at least 0.18 weight percent C and at least 0.20 weight percent Cr, each metal blade having an outer lateral surface and an inner lateral surface;
• subjecting the metal blades to a tempering treatment at a temperature ranging from 380° C. to 480° C.;
• partially plastically deforming the metal blades all around in the area of their half radius by roller-burnishing;
• treating the inner lateral surfaces of the metal blades by at least one of brush polishing and circular polishing to provide them with a roughness according to EN ISO 4287 and EN ISO 4288 (DIN 4762) represented by a maximum profile height RZ of 7.0 to 7.0 μm and an arithmetic mean roughness index Ra of 0.30 to 0.75 μm;
• applying an adhesive onto the inner lateral surface of at least one of the metal blades at a thickness of from 0.03 to 0.06 mm, measured from a center line of a roughness profile of the inner lateral surface;
• congruently combining the metal blades with their inner lateral surfaces facing each other to form a sandwich structure;
• thermally hardening the adhesive comprising, in a first hardening stage, heating at a temperature ranging from 50° C. to 70° C. and a pressure ranging from 1 to 3 kg/cm2 for a period of 10 to 16 minutes, cooling to ambient temperature, and heating, in a second hardening stage, at a temperature ranging from 140° C. to 160° C. to complete the hardening of the adhesive;
• and
• treating the outer lateral surfaces of the metal blades by at least one of brush polishing and circular polishing to provide them with a surface roughness represented by a maximum profile height RZ of 5 to 10 μm.

A circular saw blade obtainable by a process comprising:

• providing at least two circular-saw-shaped metal blades made from heat-treated sheet material of iron-based alloy, each metal blade having an outer lateral surface and an inner lateral surface;
• partially plastically deforming the metal blades all around in the area of their half radius;
• treating the inner lateral surfaces of the metal blades to provide them with a roughness according to EN ISO 4287 and EN ISO 4288 (DIN 4267) represented by a maximum profile height RZ of 3.0 to 7.0 μm and an arithmetic mean roughness index Ra of 0.30 to 0.75 μm;
• applying an adhesive onto the inner lateral surface of at least one of the metal blades;
• combining the metal blades with their inner lateral surfaces facing each other to form a sandwich structure;
• thermally hardening the adhesive while applying pressure to the sandwich structure;
• and
• treating the outer lateral surfaces of the metal blades to provide them with a surface roughness represented by a maximum profile height RZ of 5 to 10 μm.