Abstract: A method for controlling a three-phase AC motor, wherein the three-phase AC motor has a rotatably mounted rotor and a stator including a first group of coils and a second group of coils. Each of the coils generates an oscillating magnetic field upon actuation using an alternating current. The phases of the alternating currents are selected such that the superposition of the magnetic fields of the first group of coils generates a magnetic rotating field that rotates with a direction of rotation and the superposition of the magnetic fields of the second group of coils generates a magnetic rotating field that rotates counter to the direction of rotation. A system composed of a three-phase AC motor and an inverter for carrying out the control method is also described.

Abstract: A method for controlling a three-phase AC motor, wherein the three-phase AC motor has a rotatably mounted rotor and a stator including a first group of coils and a second group of coils. Each of the coils generates an oscillating magnetic field upon actuation using an alternating current. The phases of the alternating currents are selected such that the superposition of the magnetic fields of the first group of coils generates a magnetic rotating field that rotates with a direction of rotation and the superposition of the magnetic fields of the second group of coils generates a magnetic rotating field that rotates counter to the direction of rotation. A system composed of a three-phase AC motor and an inverter for carrying out the control method is also described.

Abstract: A screw locking control system includes a host, a control unit controlled by the host, an electric screw driver and a holder. The control unit includes a processor, a voltage detecting module, a power outlet for providing electricity to the electric screw driver, and a lighting signal control module electrically connected to a plurality of indicator lamps of the holder. As a result, the control unit can turn on the indicator lamps sequentially via the light signal control module, guiding operators to carry out each screw locking operation and detecting a voltage variance of the electric screw driver to determine whether each screw locking operation is qualified. Thus, the quality of the manufacturing process is consistently maintained.

Abstract: A control device for a machine tool including a feed shaft motor for driving a feed shaft and a main shaft motor for driving a main shaft is provided with: a determination unit determining whether an operation of the feed shaft motor satisfies a predetermined determination condition; and an excitation command unit outputting an excitation current command to output excitation current larger than excitation current instructed by a master control unit to the main shaft motor, when the determination unit determines that the predetermined determination condition is satisfied.

Abstract: A pneumatic motor unit includes a housing with an air inlet passage, an exhaust air outlet passage, and a rotation motor which generates a pulsating exhaust air outlet flow. The motor unit further includes a voltage depending device which communicates signals in response to at least one of an actual motor condition and operation parameter values, and a voltage generating section which is connected to the voltage depending device and which includes a piezoelectric element provided in the exhaust air outlet passage and arranged to be activated by pressure pulses of the pulsating exhaust air outlet flow from the motor. The piezoelectric element is tongue shaped and rigidly secured at one end, and is arranged to be swung in a two-way movement relative to a central rest position to thereby generate an alternating current voltage.

Abstract: The invention relates to a power tool, in particular an electrically operable hand-held power tool, having at least one tool drive shaft for direct or indirect rotary drive of an insert bit, with the insert bit being accommodated in a tool holder that is connected or detachably connected to the tool drive shaft, particularly in a replaceable fashion. At least one drive device and at least one clutch device that couples the at least one drive device to the at least one tool drive shaft is provided which has at least two different, user-selectable, limit torques. An actuating device is provided that makes it possible, with a replacement of the insert bit and/or a replacement of the tool holder, to reset the clutch device to a lower limit torque, preferably to the lowest possible limit torque.

Abstract: An arrangement and a method for controlling at least one drill parameter when drilling in rock with a rock drill, comprising an impulse-generating device arranged to induce shock waves in a tool acting against the rock with a percussive force generated via a shock wave-generating pressure. The arrangement and method comprises a control system for determining a first parameter value representing the damping pressure, determining a second parameter value representing the rotation pressure of a drill bit, determining a deviation between the second parameter value and a rotation pressure reference value, determining a parameter reference value depending on the deviation, and regulating the percussion pressure based on a function of the deviation and the parameter reference value.

Abstract: A cordless power tool (300) has a transmission (12) having multiple speed ranges In the light torque range, the speed of a motor (8) of the cordless power tool is held constant to hold an output speed of the transmission (12) constant until motor power reaches a predetermined percentage of the maximum watts out of the motor.

Abstract: A method of operating a rotary tool driven by a brushless motor including a DC brushless motor for rotationally driving a rotary bit, a torque setting clutch mechanism, a drive switch for drive-controlling a drive control circuit of the brushless motor, and a control means to rotationally drive the brushless motor by an operation of the drive switch and wherein the method includes a first step for stop-controlling of the drive control circuit, a second step for rotating forward or in reverse the brushless motor through the control and a third step for control-operating a semiconductor of an inverter circuit provided in the drive control circuit to short-circuit the magnetizing windings of the brushless motor, thus braking the rotor of the brushless motor and stopping the brushless motor.

Abstract: A power tool includes a brushless DC motor housed inside a tool housing, an input unit, and a control unit. The motor includes a rotor, a stator, and at least one sensor positioned to sense a state of the rotational position of the rotor inside the stator. A control unit controls commutation of the motor through a series of power switches coupled to the power supply. The control unit receives a current sensor state from the sensor and a user-selected speed from the input unit and determines whether the motor has reversed direction using the user-selected speed and the current sensor state. The control unit disables commutation of the motor if the motor has reversed direction until a proper current sensor state is received from the sensor.

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: An electric assembly device for tightening of fastener includes a housing and a rotation. motor which is drivingly connected to an output shaft. The output shaft has a forward portion extending out of the housing, and is adapted to carry a coupling device for releasable coupling with a fastener during tightening, which is to be performed along a first rotation axis. The device is adapted to determine an angular displacement of the housing with respect to the first rotation axis during tightening of the fastener, and to control the rotation speed of the motor during tightening based on the determined angular displacement of the housing.

Abstract: A torque system of a power tool includes a combination of a first body and a second body, in which a toothed ring is assembled; and a mode selecting assembly, a torque adjusting module and control pins disposed on the second body. The torque system further includes restricting mechanisms formed on the second body, and the control pins are respectively disposed in the restricting mechanisms. One side of the control pin has a stopper block, and the restricting mechanism includes a first stopper, a second stopper and a through hole. When the control pin is driven to rotate and the stopper block faces the first stopper or the through hole, the object of switching each operation mode is achieved.

Abstract: A torque sensing unit for a power tool arranged to generate a torque responsive signal by sensing the reaction torque transferred from a ring gear of a planetary reduction gearing to the tool housing. The torque sensing unit includes an annular torque transferring element disposed perpendicularly to the geometric axis of the ring gear and being formed with a first pair of external engagement portions for connecting the torque transferring element to the housing, a second pair of external engagement portions for connecting the torque transferring element to the ring gear, and at least one pair of weak elastically deformable zones located between the engagement portions and provided with sensors for delivering signals in response to the transferred reaction torque.

Abstract: A power tool, in particular a hand-held power tool, preferably embodied as a cordless screwdriver, is equipped with a torque limiting unit in which the release torque is settable by way of a locking brace that is equipped with a spring brace for locking elements that abut axially against parts of a planetary drive, in particular the ring gear thereof or the planet carrier thereof as a last gear stage, the spring elements of the spring brace and the locking elements being located with a radial offset from one another.

Abstract: A device has a torque-limiting unit of a power drill, wherein torque-limiting unit is intended to limit a screwdriving moment in a screwdriving function; and a power drill is provided with the new torque-limiting unit.

Abstract: An electric power tool includes a motor, a reduction mechanism, a driving unit, a bearing unit, a housing, a speed changing unit, a power switch, and an operation detecting unit which detects a reduction ratio changing operation performed by the speed changing unit to control electric power supplied to the motor. The reduction mechanism transfers the rotating power of the motor, and the driving unit transfers the rotating power of the reduction mechanism to a tip end tool. The bearing unit rotatably supports the driving unit, and the housing accommodates the motor, the reduction mechanism, the driving unit and the bearing unit. The speed changing unit changes a reduction ratio of the reduction mechanism, a power switch for turning on and off a power source of the motor.

Abstract: A drilling device prevents recurrence of an overload condition after occurrence of the overload condition, thereby improving operability and safety in the drilling device. A motor for rotating a drill is connected to an AC power source through a motor control unit, a current detector, and a power switch. A magnet is also connected to the AC power source through the power switch and a full-wave rectifier. The motor control unit rotationally drives the motor on the basis of a signal sent from a main control unit according to a state in which a motor start switch is on. The main control unit controls the motor control unit to gradually reduce a supply voltage to the motor when the motor becomes overloaded, to gradually increase the voltage to the normal power supply condition when the overload condition is vanished, and to stop power supply to the motor if the overload condition continues for a predetermined period.

Abstract: A screw fastener includes a first screwdriver including a first bit configured to fasten a first screw by engaging with a recess of the first screw, and a first motor configured to rotate the first bit, a second screwdriver including a second bit configured to fasten a first screw by engaging with a recess of the second screw, and a second motor configured to rotate the second bit, an elevator unit configured to simultaneously ascend and descend both the first screwdriver and the second screwdriver, and a controller configured to control the first motor and the second motor so that seating of the first screw can start after torquing-up of the second screw starts.

Abstract: A pneumatically striking hand-held power tool is controlled by the following steps. An acceleration (a) along a striking axis (8) of the hand-held power tool (1) is detected. A driving power is reduced if the detected acceleration (a) is greater than a threshold value (A), the threshold value (A) being selected to be greater than maximum acceleration values (a1, a2) that occur on a workpiece during the striking operation of the hand-held power tool (1).

Abstract: The present invention relates to a method and an arrangement for controlling drilling parameters when rock drilling. The arrangement is arranged such that a drill tool is connectable to a drilling machine by means of one or more drill string components, wherein the arrangement comprises means for rotating the drill tool during rock drilling and for providing a tightening torque for tightening joints between one or more from the group: drill tool, one or more drill string components and drilling machine. The arrangement is arranged to control the rotational speed of the drill tool based on available tightening torque.

Abstract: It is an object of the invention to provide an effective technique for avoiding the influence of reaction during tightening operation in the rotary fastening tool.

Abstract: A control system is provided for use in a power tool. The control system includes: a rotational rate sensor having a resonating mass and a controller electrically connected to the rotational rate sensor. The rotational rate sensor detects lateral displacement of the resonating mass and generates a signal indicative of the detected lateral displacement, such that the lateral displacement is directly proportional to a rotational speed at which the power tool rotates about an axis of the rotary shaft. Based on the generated signal, the controller initiates a protective operation to avoid further undesirable rotation of the power tool. The controller may opt to reduce the torque applied to shaft to a non-zero value that enables the operator to regain control of the tool.

Abstract: A method for controlling rock drilling and a rock drilling arrangement having at least one feed channel of a feed actuator provided with a restrictor, which causes a pressure drop if the penetration rate increases and, consequently, a flow through the restrictor increases. A pressure difference and an increase in the penetration rate can be detected by sensing the pressure before the restrictor and after the restrictor. When the feed rate increases, a hydraulic system is arranged to decrease percussion pressure.

Abstract: A method of activating a drive system with a portable power source includes performing at least two actions between the power source and the drive system to effect activation. Performing any one of the two actions without the other of the two actions will not activate the drive system. The power source is preferably a hand-held power drill or a power pack.

Abstract: A safety coupling in a percussion hammer and/or drill hammer, comprising a basic sleeve, a driven toothed wheel that is rotatably mounted on the basic sleeve and can be driven by a drive unit, a closing ring which is fastened to the basic sleeve, and a locking ring located between the driven toothed wheel and the closing ring. Said locking ring is fixed in a torsion-proof manner relative to the closing ring while being movable relative to the closing ring in an axial direction, counter to the effect of a spring mechanism. The locking ring is axially displaced while the driven toothed wheel remains in the axial position thereof when a threshold torque is exceeded.

Abstract: The invention relates to an electric power tool having a control and/or regulating device for an electric motor. It is provided that the control and/or regulating device (4) is assigned an electronic memory element (5) for at least one operating state of the electric motor (1).

Abstract: Threaded member assembling can be performed using a rotational/axial-movement-transmitting unit including an upper frame; a motor held by the upper frame; a female threaded member secured to the upper frame; a male threaded member assembled in the female threaded member, the male threaded member having a rotational/axial-movement-transmitting end at one end, and having a driven rotary end at the other end; and a joint member connecting an output terminal of the motor to the driven rotary end for transmitting rotation torque from the output terminal to the driven rotary end and for allowing axial movement of the male threaded member relative to the motor.

Abstract: An eletrical device derives power from an incoming power source to produce output plower to drive the device. The device includes circuitry that determines at lehst one characteristic of the incoming power source, and adjusts the output power used to drive the device based on the characteristic or characteristics of the incoming power source.

Abstract: A power tool such as an electric drill typically contains a gear train that couples the output spindle of the motor to the tool bit-receiving chuck. The control circuit for the power tool is operable in a ratcheting or pulse mode that causes the output spindle to rotate in discrete incremental amounts. Corresponding methods for controlling the operation of the electric motor of a power tool are also disclosed.

Abstract: The present invention is directed towards a method and an apparatus for accurately estimating the tension or clamp force in a bolted joint. An installed fastener is rotated and the torque necessary to rotate the fastener and the angle through which the fastener is rotated are measured. The angle and torque values are plotted against one another such that the angle values are plotted on an angle axis and the torque values are plotted on a torque axis. A tangent is extended from the plot towards the angle axis. The point at which the tangent crosses the angle axis is defined as zero degrees and is called the “elastic origin”. The known angle through which the fastener rotates is used to scale the angle axis. The angle from the elastic origin to the point at which the tangent was drawn is defined as the M-alpha angle and is directly proportional to the clamp force created by the bolted joint or tension in the fastener.

Abstract: A more reliable and fool-proof method and apparatus for assembling an article of assembly (e.g. with predetermined screw torque requirements) in which the article of assembly has multiple fastening locations. The method comprises holding the article of assembly fixed while providing at least two different types of targets fixed relative to the article of assembly that correspond to the individual fastening locations. Fasteners are fastened into the article of assembly at the fastening locations. When fastening is occurring at one of the fastening locations, one of the targets is being sensed. Based on the target sensed, a target output is generated that differentiates between different types of targets thereby indicating fastening location of the fastening tool. The electronic target output is used for electronic control such as for stopping a conveyor to keep the article of assembly at an assembly station until the fastening operations have been completed.

Abstract: A trigger controller for an electric power tool including a motor and a pull-trigger movable along a path having a foremost home position comprises a mechanical switch and a solid-state switch connected in series to the motor, wherein the mechanical switch includes a first moving contact, and the controller includes a second moving contact wherein the first and second moving contacts are movable to operate the mechanical and solid-state switches respectively at different predetermined travelling positions of the pull-trigger from the home position such that the two switches are caused to be initially closed at different times.

Abstract: In a method of regulating the feed force of a drilling device having a hydrostatic bore hole motor at the end of a linkage provided with a rotary and a feed drive, the feed of the linkage is set as a function of the pressure of the drive fluid for the bore hole motor in such a way that the liquid pressure remains in a predefined range or else remains constant. If the bore hole motor is equipped with an eccentricity for directional boring, for example with an angled housing, then, in addition or else independently of the feed control, directional deviations normally resulting from the linkage torsion can be compensated for by the eccentricity or the linkage being set to a corrected path angle.

Abstract: A hand-held power tool includes a torque cut-off device (2) for presetting a torque of the driving shaft (3) of the hand-held power tool and formed as a control device (4) having a rotatable control sleeve (5) including a control cam (6) having at least two cam sections (6a, 6b), and a control element (7) secured in the housing (1) of the power tool without a possibility of rotation but with a possibility of an axial displacement relative to a rotational axis (D) of the control sleeve (5) and having at least two probing sections (8a, 8b) cooperating with respective cam sections (6a, 6b) for presetting the torque.

Abstract: A method for improving the accuracy and repeatability of torque applied by discrete energy tools subjected to a wide variety of joint conditions. The method includes relating air pressure to output torque and compensating for temperature and aging variations. Additionally, the method may include a process for detecting previously tightened fasteners.

Abstract: An air cylinder is connected to a centrifugal mesh clutch mechanism connected to an air motor. A driver bit is mounted to a front face of a piston of the air cylinder. A hexagonal shaft is mounted to a rear face thereof and the hexagonal shaft is fitted to a hexagonal hole formed at an anvil of the centrifugal mesh clutch mechanism. A hole having a diameter larger than that of the hexagonal shaft is formed at center of a rotor of the air motor to thereby enable to freely lift the piston and the driver bit in the air cylinder. By simultaneously driving the air motor and the air cylinder by pressurized air, the hexagonal shaft, the piston and the driver bit advance while rotating integrally to thereby fasten a screw.

Abstract: Disclosed is a low reaction oscillating mass-based torquing tool wherein an oscillating mass is excited into near resonant oscillation by reversing pulses resulting in increased energy stored in oscillation about a dual stiffness spring which develops a higher torque output with the stiffer spring action in the tightening direction and hence tightens the fastener.

Abstract: Disclosed is a low reaction oscillating mass-based torquing tool wherein an oscillating mass is excited into near resonant oscillation by reversing pulses resulting in increased oscillation about a torsion spring to the point where the torque associated with the energy stored in the torsion spring exceeds the torque required to further tighten a fastener and the torque released from the torsion spring tightens the fastener while a biasing torque assures application of the released torque in the tightening direction only.

Abstract: A method and apparatus for correcting torque overshoot in power tools wherein torque per angle rate is sensed on each rundown and the speed of the tool is automatically adjusted to maintain torque accuracy on higher torque rate joints while maintaining speed on lower torque rate joints, automatically minimizing tool heating and maximizing job rate. In the setting of threaded fasteners, joint rates are defined as high (hard), medium or low (soft). Two torque points are defined, a first torque point and a second torque point, which are percentages of the target torque, for example 25% and 50% respectively. Two angle values are defined corresponding to the number of degrees of tool spindle rotation measured along the portion of the torque/angle curve between the first torque point and the second torque point on typical linear hard and medium joints.

Abstract: In order to prevent a looseness of bolts after main clamping, a nut runner of the present invention comprises a torque sensor for detecting a clamping torque T of a clamping unit, and a torque comparison means for comparing the clamping torque T with a clamping completion torque ST. The nut runner further includes a torque control means which gradually reduces a rotational torque of the motor until a resilience such as a torsion accumulated in the clamping unit is entirely nullified when the clamping torque T reaches the clamping completion torque ST. This ensures an effective cancellation of an inverse torque arising from the resilience and acting in the direction loosening the bolt, thus preventing the bolt from loosening.

Abstract: A method and apparatus for recovering torque lost due to joint relaxation in threaded fastener assemblies or joints. The present invention is especially adapted for use with medium-to-short or gasketed joints. In the practice of an exemplary embodiment of the invention, the torque of an electric nutrunner is pulsed at the end of a fastener tightening cycle between programmed maximum and minimum torque values which have been selected to overcome the static to dynamic torque ratio of the joint while maintaining the motor and gearing of the nutrunner in a loaded condition to ensure maximum nutrunner durability.

Abstract: A method and apparatus for tightening or loosening screw-type connections, in which the screw bolt is stimulated to oscillate longitudinally, the natural frequency of the bolt is measured and the excitation frequency is made to follow the changing natural frequency during the bolting process with a minimum, necessary excitation energy, so that the screw bolt attains a permanent state of resonance.

Abstract: A rotation device for settling a pre-molded foundation pile into the earth by imparting axial loading thereto and by imparting torque of approximately equal magnitudes to both the upper- and lowermost portions of the foundation pile. A clutch assembly comprising upper and lower pawl members is disposed on the upper end of the foundation pile. A driving rod passes through the clutch mechanism and the premolded pile. Upper and lower driving blocks of the rotation rod are faceted for nonrotationally engaging, respectively, the clutch mechanism and the lowermost portion of the foundation pile. Torque is imparted from the driving rod to the lowermost portion of the foundation pile through the lower driving block. Torque also is imparted from the driving rod through the upper driving block, the pawls of the clutch mechanism and then to the uppermost portion of the foundation pile.

Abstract: A device for facilitating directional drilling of small diameter holes radially of a mine long hole comprising a segmented sleeve for movement through a guide channel in a main drill unit. A small bit is driven by a flexible shaft which passes through the segmented sleeve. The segmented sleeve remains partially in the guide channel and extends partially out of the guide channel in a straight line from the guide channel. The segments are joined in a manner permitting a 90.degree. turn in the guide channel but allowing no curvature in the portion of the segmented sleeve extending from the guide channel.

Abstract: A control system is provided for use in a power tool. The control system includes: a rotational rate sensor having a resonating mass and a controller electrically connected to the rotational rate sensor. The rotational rate sensor detects lateral displacement of the resonating mass and generates a signal indicative of the detected lateral displacement, such that the lateral displacement is directly proportional to a rotational speed at which the power tool rotates about an axis of the rotary shaft. Based on the generated signal, the controller initiates a protective operation to avoid further undesirable rotation of the power tool. The controller may opt to reduce the torque applied to shaft to a non-zero value that enables the operator to regain control of the tool.

Abstract: A control system is provided for use in a power tool. The control system includes: a rotational rate sensor having a resonating mass and a controller electrically connected to the rotational rate sensor. The rotational rate sensor detects lateral displacement of the resonating mass and generates a signal indicative of the detected lateral displacement, such that the lateral displacement is directly proportional to a rotational speed at which the power tool rotates about an axis of the rotary shaft. Based on the generated signal, the controller initiates a protective operation to avoid further undesirable rotation of the power tool. The controller may opt to reduce the torque applied to shaft to a non-zero value that enables the operator to regain control of the tool.

Abstract: A control system is provided for use in a power tool. The control system includes: a rotational rate sensor having a resonating mass and a controller electrically connected to the rotational rate sensor. The rotational rate sensor detects lateral displacement of the resonating mass and generates a signal indicative of the detected lateral displacement, such that the lateral displacement is directly proportional to a rotational speed at which the power tool rotates about an axis of the rotary shaft. Based on the generated signal, the controller initiates a protective operation to avoid further undesirable rotation of the power tool. The controller may opt to reduce the torque applied to shaft to a non-zero value that enables the operator to regain control of the tool.