Measuring thermal expansion and the thermal crown of rolls
Systems and methods for measuring the thermal crown of rolls in-situ (e.g., at high temperature) either inside or outside the rolling mill can include sensors that measure propagation times of mechanical waves through the rolls. In some embodiments, one or more sensors are used to measure the propagation times of ultrasonic waves traveling inside the roll and normal to the roll's axis. These measurements can be taken when the roll is still hot and can be used to determine in real-time the thermal expansion at various points along the roll.
1. A method for measuring thermal expansion of a roll having a diameter and a surface comprising:
determining a reference propagation time of a reference mechanical wave propagating along at least one of the diameter or a chord of the roll and through the roll at a reference temperature of the roll, wherein the reference mechanical wave is transmitted through a coupling positioned between a sensor and the roll in a direction that lies within a plane that is normal to an axis of rotation of the roll and wherein the reference propagation time of the reference mechanical wave depends on the reference temperature of the roll;
transmitting an in situ mechanical wave at a first location on the surface and across at least one of the diameter or the chord and through the roll at an in situ temperature of the roll, the roll rotating about an axis of rotation, wherein the in situ mechanical wave is transmitted through the coupling in a direction that lies within a plane that is normal the axis of rotation during rotation of the roll;
measuring an in situ propagation time of the in situ mechanical wave through the roll at a second location, wherein the in situ propagation time of the in situ mechanical wave depends on the in situ temperature of the roll; and
determining an amount of thermal expansion of the roll, through which the reference mechanical wave and the in situ mechanical wave pass, between the reference temperature and the in situ temperature by comparing the in situ propagation time with the reference propagation time.
2. The method of claim 1 , wherein:
the in situ mechanical wave is transmitted by a transmitter and measured by a receiver; and
the reference mechanical wave is transmitted by the transmitter and measured by the receiver.
3. The method of claim 1 , wherein the body is a roll for metalworking.
4. The method of claim 3 , wherein each of the in situ mechanical wave and the reference mechanical wave propagates along the diameter of the roll.
5. The method of claim 3 , wherein each of the in situ mechanical wave and the reference mechanical wave propagates along the chord of the roll.
6. The method of claim 3 , additionally comprising:
transmitting a second in situ mechanical wave through the roll at the in situ temperature;
measuring a second in situ propagation time of the second in situ mechanical wave through the roll at a second location spaced apart from the first location; and
comparing the second in situ propagation time with the reference propagation time to determine a second amount of thermal expansion of the roll between the reference temperature and the in situ temperature.
7. The method of claim 6 , wherein the measuring the in situ propagation time and the measuring the second in situ propagation time are performed by a single sensor operable to move with respect to the roll.
8. The method of claim 1 , additionally comprising adjusting temperature control of the roll based on the amount of thermal expansion.
9. The method of claim 1 , additionally comprising:
comparing the in situ propagation time with the reference propagation time to determine an average temperature of the roll at the in situ temperature.
10. The method of claim 1 , further comprising measuring the reference temperature of the roll.
11. The method of claim 10 , wherein comparing the in situ propagation time with the reference propagation time to determine the amount of thermal expansion of the roll includes using the reference temperature of the roll.
12. The method of claim 11 , further comprising determining a speed of sound through the roll at the reference temperature, wherein comparing the in situ propagation time with the reference propagation time to determine the amount of thermal expansion of the roll includes using the speed of sound through the roll at the reference temperature.