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Device for tightening threaded joints

  • US 5,245,747 A
  • Filed: 02/04/1992
  • Issued: 09/21/1993
  • Est. Priority Date: 09/22/1989
  • Status: Expired due to Term
First Claim
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1. Apparatus for tightening a threaded joint in two subsequent tightening steps, namely a first tightening step up to a torque snug level and a second tightening step up to a predetermined pretension level, comprising:

  • a power tool (10) comprising an electric brushless motor for providing a variable speed output;

    a variable output, controllable, power supply means (11) coupled to said power tool (10) for supplying an electrical output power to said power tool; and

    control means (12) coupled to said power supply means (11) for controlling the electrical output power of said power supply means (11), said control means (12) including a programmable unit which is arranged to cause said power supply means (11) to provide a gradual change, in relation to time, of a speed related parameter so as to cause the speed of said power tool output to gradually accelerate during substantially the entire second tightening step.

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