Abstract: In an electric driver configured such that a driver bit is coupled to a drive output shaft of an electric motor via a clutch mechanism to perform screw tightening operations, an automatic screw tightening control method and a device are provided such that an appropriate screw tightened state in a screw tightening operation can be confirmed and determined, simply and reliably. In a screw tightening operation by an electric driver, at start of a predetermined screw tightening operation, a rotation amount of an electric motor at a clutch operation time by a clutch mechanism is detected, this rotation amount is set to be a target rotation amount and in the subsequent screw tightening operations, a rotation amount of the electric motor at the clutch operation time is detected and compared with the target rotation amount, respectively, so that acceptability of the respective screw tightened states is determined.

Abstract: In an electric driver configured such that a driver bit is coupled to a drive output shaft of an electric motor via a clutch mechanism to perform screw tightening operations, an automatic screw tightening control method and a device are provided such that an appropriate screw tightened state in a screw tightening operation can be confirmed and determined, simply and reliably. In a screw tightening operation by an electric driver, at start of a predetermined screw tightening operation, a rotation amount of an electric motor at a clutch operation time by a clutch mechanism is detected, this rotation amount is set to be a target rotation amount and in the subsequent screw tightening operations, a rotation amount of the electric motor at the clutch operation time is detected and compared with the target rotation amount, respectively, so that acceptability of the respective screw tightened states is determined.

Abstract: In an electric driver configured such that a driver bit is coupled to a drive output shaft of an electric motor via a clutch mechanism to perform screw tightening operations, an automatic screw tightening control method and a device are provided such that an appropriate screw tightened state in a screw tightening operation can be confirmed and determined, simply and reliably. In a screw tightening operation by an electric driver, at start of a predetermined screw tightening operation, a rotation amount of an electric motor at a clutch operation time by a clutch mechanism is detected, this rotation amount is set to be a target rotation amount and in the subsequent screw tightening operations, a rotation amount of the electric motor at the clutch operation time is detected and compared with the target rotation amount, respectively, so that acceptability of the respective screw tightened states is determined.

Abstract: In an electric driver configured such that a driver bit is coupled to a drive output shaft of an electric motor via a clutch mechanism to perform screw tightening operations, an automatic screw tightening control method and a device are provided such that an appropriate screw tightened state in a screw tightening operation can be confirmed and determined, simply and reliably. In a screw tightening operation by an electric driver, at start of a predetermined screw tightening operation, a rotation amount of an electric motor at a clutch operation time by a clutch mechanism is detected, this rotation amount is set to be a target rotation amount and in the subsequent screw tightening operations, a rotation amount of the electric motor at the clutch operation time is detected and compared with the target rotation amount, respectively, so that acceptability of the respective screw tightened states is determined.

Abstract: In an electric driver configured such that a driver bit is coupled to a drive output shaft of an electric motor via a clutch mechanism to perform screw tightening operations, an automatic screw tightening control method and a device in which setting is performed such that an appropriate screw tightened state and various inappropriate screw tightened states in a screw tightening operation can be confirmed and determined, simply and reliably are provided.

Abstract: In an electric driver configured such that a driver bit is coupled to a drive output shaft of an electric motor via a clutch mechanism to perform screw tightening operations, an automatic screw tightening control method and a device in which setting is performed such that an appropriate screw tightened state and various inappropriate screw tightened states in a screw tightening operation can be confirmed and determined, simply and reliably are provided.

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 screwdriver bit configured in such a way that when the tip of the screwdriver bit is to be fitted into a bit fitting groove of a screw, said bit fitting groove being formed on the top surface of the head of the screw, then damage is prevented from occurring on the top surface of the head of the screw, and proper fitting of the tip of said bit into the bit fitting groove is promptly and smoothly accomplished, with the result that the efficiency and safety of screw tightening work are significantly enhanced. This driver bit (30) is provided with a cross-shaped tip edge which is to be fitted into the bit fitting groove provided on the top surface of the head of the screw, said bit fitting groove consisting of a cross-shaped groove. In this driver bit (30), the tip surface of said tip edge (31) is formed as a whole into a spherical surface shape (34) by means of planishing.

Abstract: A screw which can be manufactured at a low cost with a relatively simple constitution by performing precise machining suitable for tightening a screw without employing a tapping thread structure as a threaded portion shape and machining only the distal end of the threaded portion to have a shape projecting spherically, and which can ensure smooth and quick screw tightening work without causing such problems as heat generation or molding powder at all at screw tightening. The screw includes a head (12) provided with a bit fitting groove (13) at one end, and a threaded portion (14) which is machined precisely with substantially equal circular diameter over a full length, wherein the distal end (20) of the threaded portion (14) is shaped to have a spherical projection varying in a plurality of stages.

Abstract: A screw having stabilized strength, combination with a driver bit that best fits the screw, and a header punch for producing the screw. The screw having stabilized strength has letter Y-shaped bit-fitting grooves formed in the head portion of the screw. Forming the grooves makes fitting of a corresponding driver to the screw easy, prevents occurrence of a cam-out phenomenon to enhance work efficiency, makes torque transmission to be made smoothly and sufficiently, and stabilizes strength. The bit-fitting grooves are formed in a letter Y shape that is substantially equally divided into three sections in the circumferential direction, the grooves being formed at positions required distances away from the central portion of the screw head.

Abstract: To provide a rotary tool driven by a brushless motor with which constant torque tightening work for screws or the like can always be performed properly and efficiently, in which overall downsizing and improved torque control precision enhancement can easily be achieved, and with which it is possible to eliminate occurrences of switch contact-induced sparking and wear and of the damage imparted to the peripheral electronic equipment and electronic circuitry as occurred in drive switches or torque detection mechanisms that use a conventional mechanical switch mechanism, so that the constituting parts are able to have a reduced size and an extended life.

Abstract: A screw which can be manufactured at a low cost with a relatively simple constitution by performing precise machining suitable for tightening a screw without employing a tapping thread structure as a threaded portion shape and machining only the distal end of the threaded portion to have a shape projecting spherically, and which can ensure smooth and quick screw tightening work without causing such problems as heat generation or molding powder at all at screw tightening. The screw includes a head (12) provided with a bit fitting groove (13) at one end, and a threaded portion (14) which is machined precisely with substantially equal circular diameter over a full length, wherein the distal end (20) of the threaded portion (14) is shaped to have a spherical projection varying in a plurality of stages.