Atlas Copco Aktiebolag

Atlas Copco Industrial Technique Ab

Atlas Copco Industrial Technique Aktiebolag

Atlas Copco Tools Ab

Carl-Gustaf Carlin

Stefan M Skyllermark

Erik Vilhelm Persson

Tobias Axel Lindback

Jarl-Olof Huldén

Erik Thomas Bergkvist

Lars Rickard Eriksson

Tobias Lindbäck

Bo Lennart Hellmark

The invention relates to a method of measuring elongation of a fastener by means of minimum peak side lobe (MPS) coded ultrasonic signals, and a power tool configured to performing the method. MPS coded signals with different base frequencies are transmitted into the fastener and a corresponding set of reflected signals are received from the fastener. Each reflected signal is cross-correlated with the corresponding transmitted signal, and a quality attribute of each transmitted signal is determined from the cross-correlated signals. Based on the quality attributes at least one parameter of an ultrasonic measurement signal is determined and the measurement is performed by transmitting the ultrasonic measurement signal into the fastener, and receiving a reflected ultrasonic measurement signal.

Method of measuring elongation of a fastener with ultrasound, performed by a power tool, and a power tool

An improved transformer () for use in a power tool () is disclosed, where the power tool () comprises a stationary body () and a shaft () being movable in relation to said body (). The transformer () comprises a stator () being fixed in relation to said body (110) and including one or more stator windings (). The transformer () also comprises a rotor () being movable with said shaft and including one or more rotor windings (). A magnetic field B is shared by said one or more stator and rotor windings (,) and is used for creating a contactless signal connection between said body and at least one sensor of said shaft. According to the present invention, the stator () and the rotor () are arranged for forming a mutual geometrical relationship such that said contactless signal connection is provided for different positions in both an axial direction A and a rotational direction R of said shaft. FIG.

Transformer including a contactless signal connection

A method for determining the quality of a screw joint tightening process performed by means of a torque impulse wrench, comprising clamp load determination via calculation of the time of flight for ultra sonic waves induced into the screw joint, and comparing of a total rotation movement of the screw joint with predetermined angle limit values as a target axial load level has been indicated by the time of flight of ultra sonic waves induced in the screw joint. Occurring discrepancies between the obtained total rotation movement of the screw joint and the angle limit values would indicate a faulty screw joint and/or a malfunctioning ultra sonic wave flight time measurement, which means an unacceptable tightening process quality.

Method for determining the quality of a screw joint tightening process performed by an impulse wrench

An ultrasonic measurement device and method in which an ultrasonic transducer is acoustically coupled to an object to be measured by a resilient material contact layer. The transducer transmits a plurality of consecutive ultrasonic transmit signals into the object being measured, the transmit frequency of each of the plurality of transmit signals being distinct from the frequency of the other transmit signals of the plurality of transmit signals. Signal echoes of the transmitted signals are received, and based on the received signal echoes, at least one transmit frequency to be used for ultrasonic measurement of the object is selected.

Method and device for ultrasonic measurements

A screw fastener testing method for verifying the status of a previously tightened screw fastener with respect to installed torque and actual torque growth per angle of rotation properties includes applying an increasing tightening torque on the fastener, measuring the torque magnitude at the start of rotation, of the fastener, measuring the rotational movement of the fastener after the start of rotation, calculating the torque growth per angle of rotation for a certain predetermined test interval of rotation from the start of rotation, comparing the torque magnitude indicated during rotation and the calculated torque growth per angle of rotation during the test interval of rotation with predetermined reference values (T, KR) or (TE, KP), respectively, characteristic for the actual fastener when tightened to a desired target torque level, and approving or disapproving the fastener status in view of the reference values.

Test method and tool for testing fastened fasteners

A method for quality assurance of screw joint tightening results when tightening a screw joint to a needed pretension condition (F) by means of a torque delivering power tool, wherein one or more simulation procedures of a screw joint tightening process via a specific algorithm aiming at the needed pretension condition (F) by using programmed data relating to the screw joint geometry, expected frictional conditions, power tool characteristics, a tightening strategy and suitable tightening parameter values, thereby arriving at a simulated pretension condition (F) which is compared to the resultant pretension condition (F) of a practically performed tightening process performed via the same specific algorithm, and evaluating the outcome of the comparison for quality acceptance or refusal.

Method for quality assurance of screw joint tightening

A method and apparatus for inspection and control of threaded joint tightening processes by registering over the main part of the tightening process the momentary values of the torque delivered to the joint and the angular displacement of the joint and by comparing these values in a control unit with limit values of a narrow check range and a wider control range. Indicating lamps are arranged to be initiated in response to the check and control range limits being passed. In addition to the indicating lamps being initiated an output signal from the control unit may be used for discontinuing the tightening process as the control range limits are passed. By utilizing a computer for supervising the tightening process it is possible not only to store torque and rotation values registered during the process and make a later comparison with the predetermined limits but also to arrange those limits in non linear control and check ranges for use in plastic deformation tightening applications.

Method and apparatus for inspection and fail-safe control of threaded

A method and apparatus for tightening a screw joint to a predetermined axial load F.sub.p providing the spring constant k=F/.phi. of the joint is known, wherein the joint stiffness or torque/rotation radient dM/d.phi. is calculated during the tightening process and the torque application on the joint is interrupted as a torque level M.sub.s is obtained that according to the spring constant or axial load/rotation relationship F/.phi. and the calculated joint stiffness dM/d.phi. corresponds to the predetermined axial load F.sub.p.

Method and apparatus for pretensioning screw joints

A method and apparatus for tightening a screw joint to a predetermined axial load F.sub.p providing the spring constant k=(F/.phi.) of the joint is known, wherein the torque/rotation relationship M (.phi.) is determined during the linear, elastic deformation part of the tightening process by calculating the joint stiffness (dM/d.phi.) at an arbitrarily chosen torque level M.sub.2. A theoretical, tensionless angular position .phi..sub.0 of the joint is calculated by extrapolating the determined torque/rotation relationship M (.phi.), and the tightening process is interrupted as an angular interval .DELTA..phi. from said theoretical, tensionless position .phi..sub.0 has been passed, which interval according to the spring constant k of the joint corresponds to the predetermined axial load F.sub.p.

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Tyresö, Sweden

Carl-Gustaf Carlin