Poppet valve with a formed seat, and method of making

A poppet valve comprised of a stem and a valve head formed at one end thereof,

• said valve head being provided with a rounded cladded part by welding so that a valve seat with a valve seat surface having a predetermined aperture angle is formed thereon, wherein
• the outer circumference of the valve head being cut into a predetermined dimension, and
• the surface of the cladded part being cut to form a smooth surface thereon to be forged by applying a uniform contact pressure at a temperature range possible for cold or warm forging while being less than the recrystallization temperature.

A poppet valve comprised of a stem and a valve head formed at one end thereof,

• said valve head being provided with a rounded cladded part by welding so that a valve seat with a valve seat surface having a predetermined aperture angle is formed thereon, wherein
• the surface of the cladded part being cut to form a smooth surface thereon to be applied plastic working by applying a uniform contact pressure at a temperature range possible for cold or warm forging while being less than the recrystallization temperature onto the region from the rounded cladded part to the inner circumference thereof, so that a second smooth surface is formed in the same way as the first smooth surface is formed, said second smooth surface being integral with the first smooth surface to form an enlarged valve seat surface while having an aperture angle which is larger than the aperture angle of the first smooth surface.