Abstract: A hand held electric pulse tool performs tightening operations in which torque is delivered in pulses to tighten a screw joint. The tool includes an output shaft and a sensor to determine a parameter value associated with tightening of the screw joint. The tool is operative to provide torque pulses on the output shaft in a tightening direction until a first parameter value associated with the tightening of the screw joint is reached, then pause the tightening during a first time interval, and then provide torque pulses on the output shaft in a loosening direction until a second parameter value is reached. Next the electrical pulse tool is operative to pause the tightening during a second time interval and provide torque pulses on the output shaft in the tightening direction until a third parameter value is reached.

Abstract: A method and a device for detecting the oil level in a hydraulic pulse unit at an impulse type power wrench, wherein the pulse unit comprises an oil filled pulse chamber, a motor driven inertia drive member, and a kinetic energy receiving member connected to an output shaft and intermittently coupled to the inertia drive member via an oil cushion to receive kinetic energy from the inertia drive member during repeated energy transfer phases. The rotation speed of the inertia drive member is measured both at the start of a pulse generating phase and at the end of that phase, wherein the two measured speeds are compared to each other, and when the speed at the end of the pulse generating phase exceeds the speed at the end of that phase by a certain percentage a faulty signal is emitted indicating a too low oil level in the pulse unit.

Abstract: An electric tool adapted to perform tightening operations where torque is delivered in pulses to tighten a screw joint. The electric tool including an electric motor drivingly connected to an output shaft. A processor and a memory storing software instructions that, when executed by the processor cause the electrical tool, retrieve a first power level parameter p1 indicating a first power level to be used for torque pulses up to a torque threshold. And retrieve a second power level parameter p2 indicating a second power level to be used for torque pulses above the torque threshold. Then control the speed of the electric motor, so that the electric tool provide torque pulses on the output shaft with the first power level p1 until the torque threshold is reached. And control the speed of the electric motor, so that the electric tool provide torque pulses on the output shaft with the second power level p2.

Abstract: An electric tool adapted to perform tightening operations where torque is delivered in pulses to tighten a screw joint. The electric tool including an electric motor drivingly connected to an output shaft. A processor and a memory storing software instructions that, when executed by the processor cause the electrical tool, retrieve a first power level parameter p1 indicating a first power level to be used for torque pulses up to a torque threshold. And retrieve a second power level parameter p2 indicating a second power level to be used for torque pulses above the torque threshold. Then control the speed of the electric motor, so that the electric tool provide torque pulses on the output shaft with the first power level p1 until the torque threshold is reached. And control the speed of the electric motor, so that the electric tool provide torque pulses on the output shaft with the second power level p2.

Abstract: An electric pulse tool performs a tightening operation in which torque is delivered in pulses to tighten a screw joint. The electric pulse tool includes an output shaft, a torque sensor to determine a torque value associated with tightening of the screw joint, and an angle sensor to determine an angular displacement of the screw joint. The tool provides low torque pulses of a torque value of less than 15 percent of an electric pulse tool max torque value on the output shaft until a low threshold torque value is reached. Next the tool starts measuring an angular displacement of an element of the screw joint and provides tightening torque pulses of a torque value of more than 15 percent of the electric pulse tool max torque value on the output shaft. The tool stops providing torque pulses on the output shaft when a target parameter is reached.

Abstract: An electric pulse tool for performing tightening operations, where torque is delivered in pulses to tighten a screw joint, includes an output shaft, a sensor arranged to determine a parameter value associated with the tightening of the screw joint, a processor, and a memory containing instructions executable by the processor. The electrical pulse tool operates to provide torque pulses on the output shaft in a first direction until the determined parameter value associated with the tightening of the screw joint reaches within or above a predetermined first interval including a target parameter value. The electrical pulse tool also operates to provide at least one torque pulse on the output shaft in a second direction that is opposite to the first direction in case the determined parameter value exceeds the target parameter value within a predetermined second interval.

Abstract: An electric pulse tool performs a tightening operation in which torque is delivered in pulses to tighten a screw joint. The electric pulse tool includes an output shaft, a torque sensor to determine a torque value associated with tightening of the screw joint, and an angle sensor to determine an angular displacement of the screw joint. The tool provides low torque pulses of a torque value of less than 15 percent of an electric pulse tool max torque value on the output shaft until a low threshold torque value is reached. Next the tool starts measuring an angular displacement of an element of the screw joint and provides tightening torque pulses of a torque value of more than 15 percent of the electric pulse tool max torque value on the output shaft. The tool stops providing torque pulses on the output shaft when a target parameter is reached.

Abstract: A method and a device for detecting the oil level in a hydraulic pulse unit at an impulse type power wrench, wherein the pulse unit comprises an oil filled pulse chamber, a motor driven inertia drive member, and a kinetic energy receiving member connected to an output shaft and intermittently coupled to the inertia drive member via an oil cushion to receive kinetic energy from the inertia drive member during repeated energy transfer phases. The rotation speed of the inertia drive member is measured both at the start of a pulse generating phase and at the end of that phase, wherein the two measured speeds are compared to each other, and when the speed at the end of the pulse generating phase exceeds the speed at the end of that phase by a certain percentage a faulty signal is emitted indicating a too low oil level in the pulse unit.

Abstract: A hand held electric pulse tool performs tightening operations in which torque is delivered in pulses to tighten a screw joint. The tool includes an output shaft and a sensor to determine a parameter value associated with tightening of the screw joint. The tool is operative to provide torque pulses on the output shaft in a tightening direction until a first parameter value associated with the tightening of the screw joint is reached, then pause the tightening during a first time interval, and then provide torque pulses on the output shaft in a loosening direction until a second parameter value is reached. Next the electrical pulse tool is operative to pause the tightening during a second time interval and provide torque pulses on the output shaft in the tightening direction until a third parameter value is reached.

Abstract: A method for detecting deviations between an actual angular displacement in a screw joint being tightened by an impulse type power wrench and an angular displacement measured between a power wrench housing and an impulse unit of the power wrench, includes determining a first angular interval (??1) between an end point (AE) of a first delivered impulse (A) and an end point (BE) of a succeeding second delivered impulse (B), determining a second angular interval (??2) between a start point (BS) of the second delivered impulse (B) and a start point (CS) of a succeeding third delivered impulse (C), comparing (??1) with (??2) to determine a difference between the intervals, and determining that a deviation exists between the actual angular displacement in the screw joint and the angular displacement measured between the power wrench housing and the impulse unit based on the determined difference between the intervals (??1 and ??2).

Abstract: An electric pulse tool for performing tightening operations, where torque is delivered in pulses to tighten a screw joint, includes an output shaft, a sensor arranged to determine a parameter value associated with the tightening of the screw joint, a processor, and a memory containing instructions executable by the processor. The electrical pulse tool operates to provide torque pulses on the output shaft in a first direction until the determined parameter value associated with the tightening of the screw joint reaches within or above a predetermined first interval including a target parameter value. The electrical pulse tool also operates to provide at least one torque pulse on the output shaft in a second direction that is opposite to the first direction in case the determined parameter value exceeds the target parameter value within a predetermined second interval.

Abstract: A method for detecting deviations between an actual angular displacement in a screw joint being tightened by an impulse type power wrench and an angular displacement measured between a power wrench housing and an impulse unit of the power wrench, includes determining a first angular interval (??1) between an end point (AE) of a first delivered impulse (A) and an end point (BE) of a succeeding second delivered impulse (B), determining a second angular interval (??2) between a start point (Bs) of the second delivered impulse (B) and a start point (CS) of a succeeding third delivered impulse (C), comparing (??1) with (??2) to determine a difference between the intervals, and determining that a deviation exists between the actual angular displacement in the screw joint and the angular displacement measured between the power wrench housing and the impulse unit based on the determined difference between the intervals (??1 and ??2).

Abstract: A portable power tool having a housing with a rotation motor for powering a working implement, wherein sensors are provided to indicate the motor speed and the power supply, and a programmable evaluation unit is arranged to compare indicated speed and pressure values with stored limit values, and to accumulate the total operation time of the power tool and compare that with preset time limits for tool service intervals, and an optical information unit is provided on the housing to indicate whether those stored limit values have been reached.

Abstract: A number of pre-production calibration tightenings are performed at a screw joint identical to a screw joint used in production and using the same impulse wrench as to be used in production tightening. The value of one or more tightening related parameters are registered at the attainment of the desired pre-tension level, and those parameter values are used to statistically form a basis for a reference set-up. The tightening parameter values registered during production tightening are compared to the reference set-up, and an indication is obtained as to discrepancies between the reference set-up and the actually registered parameter values to get an indication as to whether the impulse wrench is malfunctioning and/or the screw joint is faulty.

Abstract: A portable power tool having a housing with a rotation motor for powering a working implement, wherein sensors are provided to indicate the motor speed and the power supply, and a programmable evaluation unit is arranged to compare indicated speed and pressure values with stored limit values, and to accumulate the total operation time of the power tool and compare that with preset time limits for tool service intervals, and an optical information unit is provided on the housing to indicate whether those stored limit values have been reached.

Abstract: A method and a power tool system are provided for performing screw joint tightening using a pneumatic torque impulse power tool that is controlled by a control unit. A torque magnitude and a torque growth are calculated based on signals delivered by an angle sensor, and pressurized air is supplied to the power tool via a flow regulating valve which is successively adjustable between zero and full power flow. The flow regulating valve is controlled by the control unit to deliver a reduced power air flow to the power tool before and during a first delivered impulse, and then to deliver full power flow until a certain torque magnitude or a percentage of a target torque level is reached, whereafter the air supply flow is again reduced until the target torque level is reached, and when the target torque level is reached the air flow is shut off.

Abstract: In an impulse wrench there is provided an impulse unit with a motor driven inertia drive member, and a movement detecting device arranged to detect an angular movement of the inertia drive member. The movement detecting device includes a rotating disc rigidly connected to and co-rotating with the inertia drive member. The impulse wrench also includes a sensing device including four Hall-element type sensors, and the disc has a rim portion which is magnetised to provide a number of magnetic poles for activating the sensors at rotation of the inertia drive member. The sensors are arranged in pairs such that the delivered signals from the sensors in each pair has a relative phase lag of 180 degrees, and the sensors of one of the pairs are arranged to deliver signals with a phase lag of 90 degrees relative to the sensor signals from the other pair.

Abstract: A method for determining the angular displacement of the output shaft (?0) of an impulse nut runner at tightening a screw joint to a predetermined final torque level (Tf) by an impulse nut runner having a motor driven impulse unit (23) with an inertia drive member (27), an output shaft (24) to be coupled to the screw joint to be tightened and an angle sensing device (35, 38) associated with the drive member (27) and arranged to deliver signals in response to the rotational movement of the drive member (27), wherein the total angular displacement of the output shaft (24) in relation to a threshold torque level (Tt) is calculated as a difference between the total angular displacement (?Dtot) of the drive member (27) as a result of a total number of delivered impulses (Ntot) and the angle of the total number of full revolutions minus one full revolution ? (Ntot?1)·360).

Abstract: A number of pre-production calibration tightenings are performed at a screw joint identical to a screw joint used in production and using the same impulse wrench as to be used in production tightening. The value of one or more tightening related parameters are registered at the attainment of the desired pre-tension level, and those parameter values are used to statistically form a basis for a reference set-up. The tightening parameter values registered during production tightening are compared to the reference set-up, and an indication is obtained as to discrepancies between the reference set-up and the actually registered parameter values to get an indication as to whether the impulse wrench is malfunctioning and/or the screw joint is faulty.

Abstract: A method for determining the angular displacement of the output shaft (?o) of an impulse nut runner at tightening a screw joint to a predetermined final torque level (Tf) by means of an impulse nut runner having a motor driven impulse unit (23) with an inertia drive member (27), an output shaft (24) to be coupled to the screw joint to be tightened and an angle sensing device (35, 38) associated with the drive member (27) and arranged to deliver signals in response to the rotational movement of the drive member (27), wherein the total angular displacement of the output shaft (24) in relation to a threshold torque level (Tt) is calculated as a difference between the total angular displacement (?Dtot) of the drive member (27) as a result of a total number of delivered impulses (Ntot ) and the angle of the total number of full revolutions minus one full revolution [ (Ntot?1) . 360).