Impact wrench

Apparatus for tightening a joint assembly including a fastener, to a predetermined tightened condition said apparatus comprising:

• wrench means having a pulsed output for periodically applying a tightening moment to the fastener;
• first means for determining the forward rotation angle of the fastener being tightened and producing an output signal indicative thereof;
• second means receiving said first means output signal for providing an output signal representative of time over a fixed interval of said forward rotation angle;
• and
• third means receiving said first and second means output signals for developing a control signal when the predetermined tightened condition is reached.

Apparatus for tightening a joint assembly including a fastener, to a predetermined tightened condition said apparatus comprising:

• wrench means having a pulsed output for periodically applying a tightening moment to the fastener;
• first means for determining the forward rotation angle of the fastener being tightened and producing an output signal indicative thereof;
• second means receiving said first means output signal for providing an output signal representative of time over a fixed interval of said forward rotation angle;
• third means receiving said first and second means output signals for developing a control signal when the predetermined tightened condition is reached;
• and
• filter means interposed between said second and third means receiving said second means output signal for filtering spurious noise from said signal and outputting a filtered signal to said third means for use in developing said control signal when the predetermined tightened condition is reached;
• and wherein said second, third and filter means comprise programmed microprocessor means.

In an impact wrench including a hammer impacting with an anvil to rotate an output shaft operative to tighten as assembly including a fastener to its yield point by applying a tightening moment thereto, a control system comprising:

• first means for determining the forward rotation angle of the fastener being tightened and producing an output signal indicative thereof;
• second means receiving said first means output signal for providing a signal representative of time over a fixed interval of said forward rotation angle;
• and
• third means receiving said first and second means output signals for developing a control signal when the predetermined tightened condition is reached.

In an impact wrench including a hammer impacting with an anvil to rotate an output shaft operative to tighten an assembly including a fastener to its yield point by applying a tightening moment thereto, a control system comprising:

• first means for determining the forward rotation angle of the fastener being tightened and producing an output signal indicative thereof;
• second means receiving said first means output signal for providing a signal representative of time over a fixed interval of said forward rotation angle;
• third means receiving said first and second means output signals for developing a control signal when the predetermined tightened condition is reached;
• and
• filter means interposed between said second and third means receiving said second means output signal for filtering spurious noise from said signal and outputting a filtered signal to said third means for use in developing said control signal when the predetermined tightened condition is reached;
• and wherein said second, third and filter means comprise programmed microprocessor means.

An impact wrench for tightening an assembly including a fastener comprising:

• a motor;
• a hammer assembly adapted to be driven by said motor;
• an anvil adapted to be rotatingly impacted by said hammer assembly;
• wrenching means operatively attached to said anvil and adapted to drive the fastener by applying torque thereto;
• first means for determining the forward rotation angle of the fastener being tightened and producing an output signal indicative thereof;
• second means receiving said first means output signal for providing a signal representative of time over a fixed interval of said forward rotation angle;
• and
• third means receiving said first and second means output signals for developing a control signal when the predetermined tightened condition is reached.

An impact wrench for tightening an assembly including a fastener comprising:

• a motor;
• a hammer assembly adapted to be driven by said motor;
• an anvil adapted to be rotatingly impacted by said hammer assembly;
• wrenching means operatively attached to said anvil and adapted to drive the fastener by applying torque thereto;
• first means for determining the forward rotation angle of the fastener being tightened and producing an output signal indicative thereof;
• second means receiving said first means output signal for providing a signal representative of time over a fixed interval of said forward rotation angle;
• third means receiving said first and second means output signals for developing a control signal when the predetermined tightened condition is reached;
• and
• filter means interposed between said second and third means receiving said second means output signal for filtering spurious noise from said signal and outputting a filtered signal to said third means for use in developing said control signal when the predetermined tightened condition is reached,
• and wherein said second, third and filter means comprise programmed microprocessor means.

A method of tightening an assembly including a fastener to a predetermined tightened condition by periodically applying a tightening moment to the fastener with wrench means having a pulsed output, comprising the steps of:

• determining the forward rotation angle of the fastener being tightened and producing a first output signal indicative thereof;
• providing from said first output signal a second output signal representative of time over a fixed interval of said forward rotation angle;
• and
• developing from saif first and second output signals a control signal when the predetermined tightened condition is reached.

A method of tightening an assembly including a fastener to a predetermined tightened condition by periodically applying a tightening moment to the fastener with wrench means having a pulsed output, comprising the steps of:

• determining the forward rotation angle of the fastener being tightened and producing a first output signal indicative thereof;
• providing from said first output signal a second output signal representative of time over a fixed interval of said forward rotation angle;
• filtering said second output signal to remove spurious noise therefrom;
• and
• developing from said first output signal and said filtered second output signal said control signal when the predetermined tightened condition is reached;
• and wherein the steps of providing said second output signal, filtering said second output signal to remove spurious noise therefrom and developing said control signal are accomplished by programmed microprocessor means.

Apparatus for tightening a joint assembly including a fastener, to a predetermined tightened condition said apparatus comprising:

• wrench means having a pulsed output for periodically applying a tigthened moment to the fastener;
• first means for determining the forward rotation angle of the fastener being tightened and producing an output signal indicative thereof;
• second means receiving said first means output signal for providing an output signal representative of time over a fixed interval of said forward rotation angle;
• third means receiving said first and second means output signals for developing a control signal when the predetermined tightened condition is reached;
• and
• a digital filter means interposed between said second and third means receiving said second means output signal for filtering spurious noise from said signal and outputting a filtered signal to said third means for use in developing said control signal when the predetermined tightened condition is reached.

In an impact wrench including a hammer impacting with an anvil to rotate an output shaft operative to tighten an assembly including a fastener to its yield point by applying a tightening moment thereto, a control system comprising:

• first means for determining the forward rotation angle of the fastener being tightened and producing an output signal indicative thereof;
• second means receiving said first means output signal for providing a signal representative of time over a fixed interval of said forward rotation angle;
• third means receiving said first and second means output signals for developing a control signal when the predetermined tightened condition is reached;
• and
• a digital filter means interposed between said second and third means receiving said second means output signal for filtering spurious noise from said signal and outputting a filtered signal to said third means for use in developing said control signal when the predetermined tightened condition is reached.

An impact wrench for tightening an assembly including a fastener comprising:

• a motor;
• a hammer assembly adapted to be driven by said motor;
• an anvil adapted to be rotatingly impacted by said hammer assembly;
• wrenching means operatively attached to said anvil and adapted to drive the fastener by applying torque thereto;
• first means for determining the forward rotation angle of the fastener being tightened and producing an output signal indicative thereof;
• second means receiving said first means output signal for providing a signal representative of time over a fixed interval of said forward rotation angle;
• third means receiving said first and second means output signals for developing a control signal when the predetermined tightened condition is reached;
• and
• a digital filter means interposed between said second and third means receiving said second means output signal for filtering spurious noise from said signal and outputting a filtered signal to said third means for use in developing said control signal when the predetermined tightened condition is reached.

A method of tightening an assembly including a fastener to a predetermined tightened condition by periodically applying a tightening moment to the fastener with wrench means having a pulsed output, comprising the steps of:

• determining the forward rotation angle of the fastener being tightened and producing a first output signal indicative thereof;
• providing from said first output signal a second output signal representative of time over a fixed interval of said forward rotation angle;
• and
• digitally filtering said second output signal to remove spurious noise therefrom;
• and developing from said first output signal and said digitally filtered second output signal said control signal when the predetermined tightened condition is reached.