JP2009083044A - Impact tightening tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an impact tightening tool which protects an operator from abnormal striking vibrations. <P>SOLUTION: An impact tightening tool includes a drive source motor 1, a driving part 2 for receiving an output from the motor 1 and applying rotational striking vibrations to an output shaft 3, a vibration sensor 8 for detecting striking vibrations, and a motor control part 6 for determining abnormal vibrations based on the vibrations detected by the vibration sensor and stopping the motor when determining that there are abnormal vibrations. The motor is stopped if there are abnormal vibrations. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an impact tightening tool such as an impact driver or an impact wrench.

  Impact tightening tools widely used in construction sites and assembly factories due to the high workability of high rotation and high torque tighten by applying rotational impact vibration. Will be transmitted. In order to mitigate this vibration, a buffer material made of an elastomer resin or the like is disposed on the outer surface of the tool to absorb the vibration applied to the user's hand and reduce the burden.

  Here, the cushioning material is usually provided so as to effectively absorb the vibration in the frequency band assuming the vibration when the impact tightening tool is operating normally. When vibration occurs, the cushioning material does not work effectively.

Moreover, in the impact tightening tool, the actual situation is that the management of the impact vibration considering the protection of the user's health is not performed.
JP 2006-218583 A

  The present invention has been invented in view of the above-described conventional problems, and an object of the present invention is to provide an impact fastening tool that protects a user from abnormal impact vibration.

  In order to solve the above problems, an impact tightening tool according to the present invention is an impact tightening tool including a motor that is a drive source and a drive unit that receives the output of the motor and applies rotational impact vibration to an output shaft. A vibration sensor that detects the impact vibration, and a motor control unit that determines whether there is abnormal vibration based on the vibration detected by the vibration sensor and stops the motor when it is determined that there is abnormal vibration. It has characteristics. When there is abnormal vibration, the motor is stopped.

  If the motor control unit determines whether or not the vibration is abnormal based on the vibration stability based on the detected vibration peak value, amplitude, and vibration period, it can deal with a wider range of abnormal vibration. Will be able to.

  According to the present invention, since the motor stops if there is abnormal vibration, the state in which abnormal vibration is applied to the hand of the user holding the tool does not continue, and the health of the user is protected. be able to. In addition, abnormal vibration may occur when the workpiece to be tightened is not properly used, and thus urges the user to use normally.

  Hereinafter, the present invention will be described based on an embodiment shown in the accompanying drawings. FIG. 2 shows an outline of an impact tightening tool according to the present invention. The motor 1 as a driving source and the rotational force of the motor 1 are hammered. (Not shown) and a striking mechanism 2 that transmits to the output shaft 3 as well as striking (not shown). The striking mechanism 2 is not specifically shown, but is driven to rotate by the motor 1 via a speed reducer. A shaft, a hammer that is engaged with the drive shaft and rotationally driven, an anvil that is engaged with the hammer and rotationally driven, and a cam that retracts the hammer when a certain load is applied to the anvil A mechanism and a spring that engages the hammer with the anvil again after being disengaged from the anvil due to the retraction of the hammer, and the output shaft 3 including the chuck 4 is driven to rotate integrally with the anvil. Things A. In the figure, 5 is a trigger switch that adjusts the rotation speed of the motor 1, that is, the rotation speed of the hammer and the output shaft 3 according to the amount of pull-in, and 6 is a motor control unit, which is set by the trigger switch 5 using the battery 7 as a power source. The applied voltage is output to the motor 1.

  In addition, the impact fastening tool includes a vibration sensor (acceleration sensor) 8. The vibration sensor 8 may be disposed inside the housing of the tool or disposed on the outer surface of the housing.

  The output of the vibration sensor 8 is sent to the motor control unit 6, and if there is an abnormality in the vibration detected by the vibration sensor 8, the motor control unit 6 stops the motor 1 to the hand of the user holding the tool. Prevents the condition of abnormal vibration load from persisting.

  FIG. 1 is a flowchart regarding an example of abnormal vibration detection in the motor control unit 6. When tightening by impact is started, vibration obtained from the vibration sensor 6 is monitored in real time to obtain a vibration waveform (see FIG. 3). Further, the amplitude ΔA is obtained from the maximum value Amax and the minimum value (minus side maximum value) Amin, and if the amplitude ΔA is equal to or greater than the amplitude a slightly exceeding the amplitude when normally tightened, the number of times is counted. If the abnormality detection count number N exceeds the threshold value b, it is determined that the vibration stability is low and the motor 1 is stopped.

  For this reason, if abnormal vibration with an unusually large amplitude ΔA continues, the tightening operation is stopped by stopping the motor 1, so that a large burden is not placed on the user's hand holding the tool.

  Further, FIG. 1 shows only a portion where it is determined whether or not there is an abnormality from the magnitude of the amplitude ΔA, but the motor is also used when the peak values Amax and Amin greatly exceed the values during normal tightening. 1 is stopped.

  In addition, when the amplitude ΔA is too small as shown in FIG. 4 (a), when the vibration amplitude ΔA is not uniform and changes greatly as shown in FIG. 4 (b), the vibration is positive and negative. The motor 1 is stopped because there is an abnormality in different cases, or when the vibration period Δt shown in FIG. 4 (d) deviates greatly from the period during normal tightening, or the vibration period Δt is Even in the case of a large change, it is assumed that there is an abnormality and the motor 1 is stopped. That is, it is preferable to use the stability of vibration as a criterion for determining whether or not to stop the motor 1.

It is a flowchart which shows the operation | movement in an example of embodiment of this invention. It is a schematic diagram same as the above. It is a time chart which shows a vibration waveform same as the above. (a)-(d) is a time chart which shows the abnormal vibration waveform same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 Drive part 3 Output shaft 6 Motor control part 8 Vibration sensor

Claims (2)

  A vibration sensor for detecting impact vibration and vibration detected by the vibration sensor in an impact tightening tool including a motor as a drive source and a drive unit that receives the output of the motor and applies rotational impact vibration to an output shaft. An impact tightening tool comprising: a motor control unit that stops a motor when it is determined whether or not there is abnormal vibration based on whether or not there is abnormal vibration.   2. The impact according to claim 1, wherein the motor control unit determines whether or not the vibration is abnormal based on the stability of the vibration based on the detected peak value, amplitude and vibration period of the vibration. Tightening tool.

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