Screw tightening system, controller, and non-transitory storage medium
AssigneeOMRON Corporation
InventorsShu Biwaki, Zhiqiang Liu, Masahiro Murai, Yuki Tsuchihashi
Life of this patent
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Abstract
A screw tightening system includes an actuator including a driver bit that rotationally drives a screw and a motor coupled with driver bit, and a controller that controls actuator. Controller includes an acquirer that acquires torque values of a torque generated in a motor, a calculator that calculates a standard deviation of the torque values in a temporary tightening period, and a determiner that determines that there is an abnormality when a ratio of the standard deviation to a reference standard deviation exceeds a first threshold value.
Claims11
A screw tightening system comprising:
- an actuator including a driver bit configured to rotationally drive a screw, a motor coupled with the driver bit, a driver configured to drive the motor, and a load sensor configured to detect an axial load on the driver bit;
- and
- a controller configured to control the actuator,
- wherein:
- the driver is configured to calculate a torque value of a torque generated in the motor,
- the controller includes:
- an acquirer configured to acquire torque values of the torque from the driver,
- a calculator configured to calculate a standard deviation of the torque values acquired in a temporary tightening period from when the screw engages with a screw hole until when the screw is seated in the screw hole, and
- a determiner configured to determine that there is an abnormality when a ratio of the standard deviation to a reference standard deviation exceeds a first threshold value, and
- the determiner is configured to determine that there is an abnormality when the ratio does not exceed the first threshold value and the axial load detected by the load sensor exceeds a second threshold value.
A controller configured to control an actuator including a driver bit configured to rotationally drive a screw, a motor coupled with the driver bit, and a driver configured to drive the motor and calculate a torque value of a torque generated in the motor, the controller comprising:
- an acquirer configured to acquire torque values of the torque from the driver;
- a calculator configured to calculate a standard deviation of the torque values acquired in a temporary tightening period from when the screw engages with a screw hole until when the screw is seated in the screw hole;
- and
- a determiner configured to determine that there is an abnormality when a ratio of the standard deviation to a reference standard deviation exceeds a first threshold value,
- wherein:
- the actuator includes a load sensor configured to detect an axial load on the driver bit and
- the determiner is configured to determine that there is an abnormality when the ratio does not exceed the first threshold value and the axial load detected by the load sensor exceeds a second threshold value.
A non-transitory storage medium configured to store a control program which when accessed and executed by one or more processors of a computer that is connected to an actuator including a driver bit configured to rotationally drive a screw, a motor coupled with the driver bit, a driver configured to drive the motor and calculate a torque value of a torque generated in the motor, and a load sensor configured to detect an axial load on the driver bit, is configured to cause the one or more processors to:
- acquire torque values of the torque from the driver,
- calculate a standard deviation of the torque values acquired in a temporary tightening period from when the screw engages with a screw hole until when the screw is seated in the screw hole,
- determine that there is an abnormality when a ratio of the standard deviation to a reference standard deviation exceeds a first threshold value, and
- determine that there is an abnormality when the ratio does not exceed the first threshold value and the axial load detected by the load sensor exceeds a second threshold value.
Dependencies are inferred from the claim text.