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`WHAT IS CLAIMED IS
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`1. A rotary impact tool comprising:
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`a rotary driving mechanism including a motor for rotating a
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`driving shaft;
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`a hammer engaged with the driving shaft;
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`an output shaft to which a driving force is applied by impact
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`blow of the hammer;
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`a main switch operated by a user for controlling fastening
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`operation;
`a torque setting switch used by a user for setting a fastening
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`torque;
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`a torque calculator for calculating a fastening torque; and
`a controller for controlling on and ofi‘ of the motor based on
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`switching on and off of the main switch, an output of the torque '
`calculator and the fastening torque set in the torque setting switch,
`and having a normal fastening mode and a tight fastening mode;
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`wherein
`a tight fastening mode setting switch used for setting the tight
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`fastening mode is further comprised; and
`when the tight fastening mode setting switch is switched on,
`the controller continuously drives the rotary driving mechanism so as
`to perform tight fastening operation continuously.
`2. The rotary impact tool in accordance with claim 1 further
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`comprising:
`a rotation angle sensor for sensing rotation angle of the output
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`FROM liaya&ftssoci§tes 06-6244-5972
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`20055 55118(1)13:34/Efil3:23/Sz§§%5306128450 P 16
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`shaft to which rotation force due to impact blow of the hammer is
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`applied or a rotation angle of a shaft of the motor; wherein
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`the torque calculator calculates the fastening torque based on
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`an output of the rotation angle sensor; and
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`the controller stops driving of the motor when the rotation
`angle obtained from an output of the rotation angle sensdr becomes
`equal to or larger than a predetermined reference value in the tight
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`fastening mode.
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`3.- The rotary impact tool in accordance with claim 2 further
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`comprising:
`a tight fastening angle setting switch used for setting or
`varying the predetermined reference value set in the tight fastening
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`mode.
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`4. The rotary impact tool in accordance with claim 1,
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`wherein
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`the controller stops driving of the motor when a quantity of
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`impact blows of the hammer corresponding to the fastening torque set
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`in the torque setting switch.
`5. The rotary impact tool in accordance with claim 1,
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`wherein
`the controller increases a level of phase of the fastening torque
`set in the torque setting switch by one, when a number of tight
`fastening operations reaches to a predetermined times.
`6. The rotary impact tool in accordance with claim 2,
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`wherein
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`the controller increases a level of phase of the fastening
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`torque set in the torque setting switch by one, when a number of tight
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`fastening operations reaches to a predetermined times.
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`7. The rotary impact tool in accordance with claim 3,
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`wherein
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`the controller increases a level of phase of the fastening torque
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`set in the torque setting switch by one, when a number of tight
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`fastening operations reaches to a predetermined times.
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`8. The rotary impact tool in accordance with claim 4,
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`wherein
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`the controller increases a level of phase of the fastening torque
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`set in the torque setting switch by one, when a number of tight
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`fastening operations reaches to a predetermined times.
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