Ultrasonic testing apparatus for turbine forks and method thereof

An ultrasonic testing apparatus for a turbine fork of a turbine blade joined to a turbine disc, comprising:

• an ultrasonic testing sensor for sending ultrasonic waves and receiving reflected waves of the ultrasonic waves;
• a sensor mounting apparatus for mounting said ultrasonic testing sensor on a flat portion of a side surface of said turbine fork with said turbine blade joined to said turbine disc;
• an ultrasonic testing equipment for inspecting internal and external surfaces of said turbine fork by using the reflected waves, which are received by said ultrasonic testing sensor, from the internal surface of said turbine fork;
• wherein first graduations exist on a surface of said arm member along the longitudinal direction of the through-groove beside the through-groove;
• and second graduations exist on a surface of one end of said first rotating member;
• and third graduations exist on a surface of one end of said second rotating member.

An ultrasonic testing for a turbine fork with a turbine blade joined to a turbine disc, comprising:

• an ultrasonic testing sensor for sending ultrasonic waves and receiving reflected waves of the ultrasonic waves;
• a pair of fixing pawls and a magnet holder for setting said ultrasonic testing sensor on a flat portion, which is perpendicular to an axial direction of a turbine disc, parallel with a radial direction of said turbine disc, and parallel with a longitudinal direction of a turbine blade joined to said turbine disc, on a side surface of said turbine fork with said turbine blade;
• a first rotating member attached to said magnet holder;
• an arm member, in which a through-groove is formed in a longitudinal direction of itself, turned around said first rotating member;
• a second rotating member, by which said ultrasonic testing sensor is moved along the longitudinal direction of said arm member, installed to said arm member in such a way that it passes through the through-groove;
• an ultrasonic testing sensor mounting tool having graduations and installed to said first rotating member, said arm member and said second rotating member;
• and
• an ultrasonic testing equipment connected electrically to said ultrasonic testing sensor.

An ultrasonic testing method for a turbine fork of a turbine blade joined to a turbine disc, comprising the steps of:

• obtaining at least one reference signal by performing ultrasonic testing for a reference test object having no defect and of the same size as a test object part of said turbine fork by an ultrasonic testing apparatus, comprising:
• an ultrasonic testing sensor for sending ultrasonic waves and receiving reflected waves of the ultrasonic waves;
• a pair of fixing pawls and a magnet holder for setting said ultrasonic testing sensor on a flat portion, which is perpendicular to an axial direction of a turbine disc, parallel with a radial direction of said turbine disc, and parallel with a longitudinal direction of a turbine blade joined to said turbine disc, of a side surface of said turbine fork with said turbine blade;
• a first rotating member attached to said magnet holder;
• an arm member, in which a through-groove is formed in a longitudinal direction of itself, turned around said first rotating member;
• a second rotating member, by which said ultrasonic testing sensor is moved along the longitudinal direction of said arm member, installed to said arm member in such a way that it passes through the through-groove;
• an ultrasonic testing sensor mounting tool having graduations installed to said first rotating member, said arm member and said second rotating member;
• and
• an ultrasonic testing equipment connected electrically to said ultrasonic testing sensor,
• setting said ultrasonic testing sensor on said flat portion on the side surface of said turbine fork with said turbine blade joined to said turbine disc by using said sensor mounting apparatus;
• obtaining ultrasonic testing signals by performing ultrasonic testing for said test object part of said turbine fork by said set ultrasonic testing sensor;
• and
• determining whether a defect is present by comparing the ultrasonic testing signals with the reference signals.

An ultrasonic testing method for a turbine fork of a turbine blade joined to a turbine disc, comprising the steps of:

• obtaining reference signals by performing ultrasonic testing for a reference test object having no defect and of the same size as a test object part of said turbine fork by an ultrasonic testing apparatus, comprising:
• an ultrasonic testing sensor for sending ultrasonic waves and receiving reflected waves of the ultrasonic waves;
• a sensor mounting apparatus for mounting said ultrasonic testing sensor on a flat portion of a side surface of said turbine fork with said turbine blade joined to said turbine disc;
• and
• an ultrasonic testing equipment for inspecting internal and external surfaces of said turbine fork by using the reflected waves, which is received by said ultrasonic testing sensor, from the internal surface of said turbine fork;
• wherein said sensor mounting apparatus has a pair of fixing pawls set to said turbine blade, a magnet holder being fixed on said turbine disc by magnetic force, a first rotating member attached to said magnet holder, an arm member, in which a through-groove is formed in a longitudinal direction of itself, turned around said first rotating member, a second rotating member, by which said ultrasonic testing sensor is moved along the longitudinal direction of said arm member, installed to said arm member in such a way that it passes through the through-groove, and a spring pressing said ultrasonic testing sensor against said flat portion of said side surface of said turbine fork together with said arm member, and surrounding said first rotating member,
• setting said ultrasonic testing sensor on said flat portion of said side surface of said turbine fork with said turbine blade joined to said turbine disc by using said sensor mounting apparatus;
• obtaining ultrasonic testing signals by performing ultrasonic testing for said test object part of said turbine fork by said set ultrasonic testing sensor;
• and
• determining whether a defect is present by comparing the ultrasonic testing signals with the reference signals.