Algorithms and methods for controlling threading of pipe

A method for forming threads in a workpiece using a tool including a tool head having at least one threading die, an electric motor rotatably powering the tool head, a sensor for measuring electrical current consumed by the motor, a controller for controlling operation of the motor, a counter of motor rotations, and memory provisions for saving motor-rotation counts, wherein the method comprises:

• rotating the tool head that includes at least one threading die, by use of the motor;
• measuring electrical current consumed by the motor, by use of the sensor;
• comparing the measured electrical current to a first threshold value, whereby if the first threshold value has not been met, the measuring and comparing operations are repeated;
• if the first threshold value has been met, incrementing the counter of motor rotations to produce a cumulative motor rotation count;
• performing a second comparison of the cumulative motor rotation count to a second threshold value, whereby if the second threshold value has not been met, the incrementing and second comparing operations are repeated;
• if the second threshold value has been met, reversing a direction of rotation of the tool head;
• performing another measurement of electrical current consumed by the motor, by use of the sensor;
• performing a third comparison of the measured electrical current after reversing the direction of rotation of the tool head to a no-load current value, whereby if the no-load current value has not been met, the performing another measurement of electrical current consumed and third comparing operations are repeated;
• if the no-load current value has been met, discontinuing tool operation or braking tool rotation.

A method for forming threads in a workpiece using a tool including a tool head having at least one threading die, an electric motor rotatably powering the tool head, a sensor for measuring angular velocity, an angular velocity counter, a timer for measuring a time step, a controller, and memory provisions, the method comprising:

• setting the angular counter to zero;
• rotating the tool head that includes the at least one threading die, by use of the motor;
• measuring angular velocity, by use of the sensor;
• comparing the measured angular velocity to a first threshold value, whereby if the first threshold value has not been met, the setting, measuring, and comparing operations are repeated;
• if the first threshold value has been met, multiplying the measured angular velocity and the time step to produce an angle value;
• summing the angle value to produce an angular counter value;
• performing a second comparison of the angular counter value to a second threshold value, whereby if the second threshold value has not been met, the measuring, comparing, multiplying, summing, and second comparing operations are repeated;
• if the second threshold value has been met, discontinuing tool operation or braking tool rotation.

A method for forming threads in a workpiece using a tool including a tool head having at least one threading die, an electric motor rotatably powering the tool head, a controller for controlling operation of the motor, a counter of motor rotations, and memory provisions for saving motor-rotation counts, wherein the method comprises:

• rotating the tool head that includes at least one threading die, by use of the motor;
• incrementing the counter of motor rotations to produce a cumulative motor rotation count;
• and
• performing a first comparison of the cumulative motor rotation count to a first threshold value, whereby if the first threshold value has not been met, the incrementing and first comparing operations are repeated.