Ultrasonic tool confirmation sensor

#The present invention relates generally to a method and a system for detecting the presence of a tool in a cutting machine.

#Mass production assembly lines and unmanned machining assembly lines require simple, reliable, and automatic tool breakage detection systems. The ability to detect tool breakage is important to produce high quality parts at a high rate of speed. The breakage of a cutting tool, which is a relatively frequent occurrence, can be very disruptive to an assembly line if not detected immediately.

#Most current tool breakage detection systems rely on some form of contact with the tool or require complex equipment. In addition, many of these detection systems are sensitive to debris from the cutting operation and thus require a clean operating environment. A clean environment can be difficult to maintain on an assembly line.

#Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

#FIG. 1 is a schematic view illustrating a tool detection system;

#FIG. 2 is a schematic diagram of a control unit circuit.

#Referring to FIG. 1, a tool detection system 10 is associated with tool drive unit 12 mounted on a tool and a sensor carriage 14. Carriage 14 moves in both a horizontal and a vertical direction to enable it to be positioned over a workpiece 16 and upon sufficient vertical downward movement to drive a tool 18 into the workpiece 16. A shaft (not shown) from the tool drive unit 12 engages a tool chuck 20 which, in conjunction with the tool drive unit 12, rotates the tool 18. A control unit 22 is also mounted adjacent carriage 14. A sensor nozzle 24 is attached to move with carriage 14, as shown schematically at 26. The tool 18 and carriage 14 may move vertically relate to nozzle 24.

#An ultrasonic transducer 28 is mounted within the sensor nozzle 24, and an electric cable 30 couples the control unit 22 to the ultrasonic transducer 28. A stream of fluid 32 enters the sensor nozzle 24 through a fluid inlet 34, passes out through a set of fluid holes 36, and exits the sensor nozzle 24 through a sensor nozzle outlet 38 in a stream of fluid 32 to impinge on the tool 18. The fluid stream 32 has a laminar flow and may be the known coolant or cleaning fluid which is directed at the tool 18 as it cuts the workpiece 16. An ultrasonic wave 40 is generated by the ultrasonic transducer 28 and exits the sensor nozzle 24. Wave 40 is propagated through the stream of fluid 32 and directed at tool 18. An echo wave 42 is reflected from the tool 18 back through the stream of fluid 32 into the sensor nozzle 24 and is detected by the ultrasonic transducer 28. Thus, the ultrasonic transducer 28 functions both as a generator of the ultrasonic wave 40 and a detector of the echo wave 42. Such transducers are known in the art and its structure forms no portion of this invention. A signal from the detected echo wave 42 is sent to the control unit 22 via the electric cable 30.

#The transducer is provided by a piezoelectric element 44 mounted in the ultrasonic transducer 28. The diameter of the piezoelectric element 44 is similar in size to the diameter of the sensor nozzle outlet 38.