Apparatus and method for ultrasonic particle detection in molten metal

A process for ultrasonically inspecting a molten body, said process comprising:

• (a) fixedly placing an apparatus in contact with said molten body;
• (b) generating ultrasonic waves with a pulser/receiver system of the apparatus;
• (c) transmitting said waves and receiving resultant signals with a piezoelectric element through a buffer rod, said rod acting as a coupling medium between said piezoelectric element and said molten body, said rod having an upper end shaped to influence flow of a coolant about the rod and integral opposite lower end for contacting said molten body, said rod being made substantially of the same material as said molten body;
• (d) controlling the amount of cooling to prevent substantial meltback of said rod and to prevent substantial buildup of molten body material on said rod such that said lower end of said rod extends approximately 1/4-inch into said molten body beyond said housing when said apparatus is partially immersed in said body and when said rod and said body reach thermal equilibrium;
• and
• (e) interpreting the resultant signals with the pulser/receiver system.

An apparatus for sensing particles in a molten body, said apparatus comprising:

• (a) a first ultrasonic piezoelectric element;
• (b) a second ultrasonic piezoelectric element;
• (c) a first buffer rod for transmitting acoustic energy between said first piezoelectric element and said molten body, said first rod having a cavity for holding said first piezoelectric element, an upper end shaped to influence flow of coolant about the first rod and an integral opposite lower end for contacting said molten body;
• (d) a second buffer rod for receiving acoustic energy between said second piezoelectric element and said molten body, said second rod having a cavity for holding said second piezoelectric element, said second rod having an upper end shaped to influence flow of said coolant about the second rod and an integral opposite lower end for contacting said molten body, said first and second buffer rods being made substantially of the same material as said molten body;
• (e) a housing located around said piezoelectric elements and rods for shielding said piezoelectric elements and said rods from the molten body, said housing having openings in which said lower ends of the rods are disposed to contact the molten body;
• (f) a first shroud around said upper end of said first rod and serially connected to a first sleeve disposed around said first rod and said first piezoelectric element, said first shroud and said first sleeve providing an internal first cooling means for circulation of said coolant about said first rod, said first cooling means controlling the amount of cooling sufficient to prevent substantial meltback of said first rod and to prevent substantial buildup of molten body material on said first rod such that said lower end of said first rod extends approximately 1/4-inch into said molten body beyond said housing when said apparatus is partially immersed in said body and when said first rod and said body reach thermal equilibrium;
• (g) a second shroud around said upper end of said second rod and serially connected to a second sleeve disposed around said second rod and said second piezoelectric element, said second shroud and said second sleeve providing an internal second cooling means for circulation of said coolant about said second rod, said second cooling means controlling the amount of cooling sufficient to prevent substantial meltback of said second rod and to prevent substantial buildup of molten body material on said second rod such that said lower end of said second rod extends approximately 1/4-inch into said molten body beyond said housing when said apparatus is partially immersed in said body and when said second rod and said body reach thermal equilibrium;
• and
• (h) means for directing the coolant between said shrouds and the upper ends of said rods.

An apparatus for sensing particles in a molten aluminum, said apparatus comprising:

• (a) a first ultrasonic piezoelectric element;
• (b) a second ultrasonic piezoelectric element;
• (c) an aluminum or aluminum alloy first buffer rod for transmitting acoustic energy between said first piezoelectric element and said molten aluminum, said first rod having a cavity for holding said first piezoelectric element;
• (d) an aluminum or aluminum alloy second buffer rod for receiving acoustic energy between said second piezoelectric element and said molten aluminum, said second rod having a cavity for holding said second piezoelectric element, each of said first rod and said second rod having a cone-shaped upper end to influence flow of air about the rods and an integral opposite lower end for contacting said molten aluminum, said cavity of each rod located between 3 and 6 inches from said opposite lower end of each said rod, each of said rods having a diameter between each said cone-shaped upper end and each said opposite lower end of approximately two inches and a diameter of each said opposite lower end of approximately one inch;
• (e) a first shroud around said upper end of said first rod and serially connected to a first sleeve disposed around said first rod and said first piezoelectric element, said first shroud and said first sleeve providing an internal first cooling means for circulation of said air about said first rod, said first cooling means cooling said lower end of said first rod such that said apparatus reaches and maintains thermal equilibrium with said molten aluminum with substantially little melting of said first rod in the molten aluminum when said apparatus is partially immersed in said molten aluminum;
• (f) a second shroud around said upper end of said second rod and serially connected to a second sleeve disposed around said second rod and said second piezoelectric element, said second shroud and said second sleeve providing an internal second cooling means for circulation of said air about said second rod, said second cooling means cooling said lower end of said second rod such that said apparatus reaches and maintains thermal equilibrium with said molten aluminum with substantially little melting of said second rod in the molten aluminum when said apparatus is partially immersed in said molten aluminum;
• (g) means for directing the air between said shrouds and the upper ends of said rods;
• (h) a housing located around said piezoelectric elements and rods for shielding said piezoelectric elements and said rods from the molten aluminum, said housing having openings in which said lower ends of the rods are disposed to contact the molten aluminum, said first and second cooling means controlling the amount of cooling sufficient to prevent substantial meltback of said rods and to prevent substantial buildup of molten aluminum on said rods such that said lower end of said rods extends approximately 1/4-inch into said molten aluminum beyond said housing when said apparatus is partially immersed in said molten aluminum and when said rods and said molten aluminum reach thermal equilibrium;
• and
• (i) a pulser/receiver system for operating said piezoelectric elements, said system adapted to generate;
• receive and interpret signals between said piezoelectric elements and the molten aluminum.