Impact rotary tool, torque estimation method, and non-transitory recording medium

1 . An impact rotary tool comprising:

a driver configured to perform a turning operation;

a drive shaft configured to be turned by the driver;

a hammer configured to be fitted to an outer perimeter of the drive shaft such that the hammer is movable in an axial direction of the drive shaft and rotatable in a turning direction in which the drive shaft turns;

an anvil configured to receive impact applied by the hammer in the turning direction;

a travel distance measuring device configured to measure a parameter relating to a hammer travel distance through which on application of the impact to the anvil by the hammer, the hammer moves away from the anvil along the axial direction from a location of the application of the impact to the anvil by the hammer;

a torque estimator configured to estimate, based on at least the parameter, a torque value generated by the impact, and

a controller configured to control the driver in accordance with vector control, wherein

the driver is configured to be supplied with a torque current in accordance with the vector control performed by the controller, and

the travel distance measuring device is configured to

measure a variation amount of the torque current in a period from when the hammer applies impact to the anvil to when the hammer next applies impact to the anvil and measure, as the parameter, the hammer travel distance itself, the hammer travel distance being measured based on the variation amount.

2 . The impact rotary tool of claim 1 , further comprising a rotational velocity measuring device configured to measure a rotational velocity of at least one of the drive shaft or the hammer, wherein

the torque estimator is configured to estimate the torque value on a basis of the parameter relating to the hammer travel distance and the rotational velocity.

3 . The impact rotary tool of claim 1 , wherein

the travel distance measuring device is configured to

perform a plurality of number of times of measurements of the variation amount in one machining work task and

measure the hammer travel distance when the variation amount shows an increasing tendency in the plurality of number of times of measurements.

4 . The impact rotary tool of claim 3 , wherein

the travel distance measuring device is configured to, when the variation amount successively increases a predetermined number of times in the plurality of number of times of measurements, determine that the variation amount shows the increasing tendency.

5 . The impact rotary tool of claim 1 , wherein

the travel distance measuring device is configured to measure the hammer travel distance after the hammer applies impact to the anvil a predetermined number of times in one machining work task.

6 . A torque estimation method of estimating a torque value generated by an impact rotary tool including: a driver configured to perform a turning operation; a drive shaft configured to be turned by the driver; a hammer configured to be fitted to an outer perimeter of the drive shaft such that the hammer is movable in an axial direction of the drive shaft and rotatable in a turning direction in which the drive shaft turns; an anvil configured to receive impact applied by the hammer in the turning direction, the torque value being produced by the impact; and a controller configured to control the driver in accordance with vector control, the torque estimation method comprising:

a travel distance measurement step of measuring a parameter relating to a hammer travel distance through which on application of the impact to the anvil by the hammer, the hammer moves away from the anvil along the axial direction from a location of the application of the impact to the anvil by the hammer; and

a torque estimation step of estimating, based on at least the parameter, a torque value generated by the impact, wherein

the driver is configured to be supplied with a torque current in accordance with the vector control performed by the controller, and

the travel distance measurement step includes

measuring a variation amount of the torque current in a period from when the hammer applies impact to the anvil to when the hammer next applies impact to the anvil and

measuring, as the parameter, the hammer travel distance itself, the hammer travel distance being measured based on the variation amount.

7 . A non-transitory recording medium recording a program configured to cause a computer system to execute the torque estimation method of claim 6 .