JP2003266328A - Method for confirming completion of screw tightening of electric screwdriver and device for confirming completion of screw tightening of electric screwdriver - Google Patents

Abstract

(57) [Summary] [Problem] To provide a method for confirming the completion of screw tightening of an electric screwdriver and a device for confirming the completion of screw tightening of an electric screwdriver which can confirm the completion of screw tightening without modifying an electric screwdriver currently on the market. provide. SOLUTION: When tightening a screw with an electric screwdriver, a change in the current value at the time of starting and locking of an alternating current flowing through the electric screwdriver is detected, and a screw tightening completion signal is taken out to complete the screw tightening. Make sure that

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for confirming completion of screw tightening of an electric screwdriver and a device for confirming completion of screw tightening of an electric screwdriver, and particularly to a confirmation method and a small size and lightweight of a small and light AC electric screwdriver. The present invention relates to a device for confirming completion of screw tightening of an AC electric screwdriver.

[0002]

2. Description of the Related Art Generally, commercially available electric screwdrivers are
It has a built-in control circuit to stop the motor when the screw tightening torque reaches a certain value. When checking the screw tightening, it is judged that the operator has completed the screw tightening because the motor of the electric screwdriver has stopped.

Conventionally, as an electric driver, for example, a device such as an electric driver described in Japanese Utility Model Laid-Open No. 05-080670 has been known. This device counts the amount of rotation of the tightening member rotated by the DC motor with an encoder and a pulse counter that counts its output pulses, and feedback-controls the DC motor so that this count value is the amount of rotation set by the setting circuit. As a result, the screwing amount of the tightened member rotated by the tightening member is automatically adjusted to a predetermined value.

[0004]

However, when the screw tightening is left to the operator's discretion, the screw is stopped before the tightening torque reaches a certain value, or the screw slips (the screw thread is damaged). There was a mistake in work such as deciding that the tightening was completed in this state, or forgetting to tighten the screws when tightening multiple screws. In order to detect such an error in screw tightening work, it is necessary to be able to output a signal indicating that screw tightening has been completed.

In this respect, as a means for taking out a signal indicating the completion of screw tightening, a method of incorporating a torque sensor in the electric driver or taking out a signal of clutch actuation can be considered. However, it is not suitable for an electric screwdriver that requires a small size and light weight due to its complicated structure.

The above problems cannot be overcome even by a device such as an electric driver described in Japanese Utility Model Laid-Open No. 05-080670.

Therefore, the present invention is a method for confirming the completion of screw tightening of an electric screwdriver, by extracting a screw tightening completion signal without modifying the electric screwdriver currently on the market. Another object of the present invention is to provide a confirmation device of screw tightening completion of an electric screwdriver.

[0008]

According to a first aspect of the present invention, there is provided a method for confirming completion of screw tightening of an electric screwdriver in a method of tightening a screw with an electric screwdriver, when an alternating current flowing through the electric screwdriver is started. It is characterized by detecting a change in current value at the time of locking and confirming that screw tightening is completed.

According to the second aspect of the invention, the method for confirming the completion of screw tightening of the electric screwdriver is to confirm the screw tightening by the method of claim 1 and set the number of continuous tightening in advance to compare. It is characterized by making a judgment and confirming tightening.

According to the third aspect of the present invention, the device for confirming the completion of screw tightening of the electric driver is provided with a current converter in the commercial power supply circuit for driving the electric driver, and counts the number of times the peak value appears within a certain period of time. It is characterized in that it has a counter for setting and comparing the number of fastenings within a fixed cycle.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a method for confirming completion of screw tightening of an electric screwdriver and a device for confirming completion of screw tightening of an electric screwdriver according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a graph showing changes in the value of the current flowing through the electric driver. The magnitude of the current instantaneously increases because the starting current flows at the time of startup, a constant current flows during screwing, and the current value increases again when locked.
The current converter 1 which shows these two peak values in FIG.
It was detected by. In this way, when tightening the screw with a commercially available electric screwdriver, the completion of screw tightening can be confirmed without improving the electric screwdriver by detecting the change in the current value when the AC current flowing through the electric screwdriver is started and locked. can do.

FIG. 2 is a block diagram showing the configuration of a circuit for taking out the change in the value of the current flowing through the electric driver.

First, the current converter 1 detects the current flowing through the electric driver. The current signal detected here is sent to the current settling circuit 2 where the effective value component is extracted.

Next, in the peak value detection circuit 3, the slash level is set at a predetermined current value, for example, 0.3 mA, and the peak value is fixed by performing a comparison operation with the detected current value.

With the appearance of this peak value as a trigger, the next time setting circuit 4 sets a predetermined time, for example, 0.5 se.
c. When the next peak value appears within the range, it is sent to the next tightening frequency setting circuit 5 and counted up.

The tightening frequency setting circuit 5 is provided with a function of setting the tightening frequency in advance, the set tightening frequency and the actual tightening frequency are compared and judged, and the result is the next tightening frequency display circuit 6. To be displayed. In this way, the number of continuous tightening is set in advance, and the tightening is confirmed by comparing and judging.

In the time setting circuit 4, for example, 0.5 sec. If the next peak value does not appear within the range, the next tightening failure display circuit 7 displays the value.

A current converter is provided in a commercial power supply circuit for driving an electric screwdriver to count the number of times a peak value appears within a certain period of time, and a counter for setting and comparing the number of tightening screws within a certain cycle is attached to complete screw tightening of the electric screwdriver. A circuit for determining is provided.

[0020]

According to the invention as set forth in any one of claims 1 to 3, the operation of the electric screwdriver is known by AC current without knowing the operation of the electric screwdriver, and the screw tightening is completed. By detecting, it is possible to confirm the completion of screw tightening.

Further, according to the invention described in any one of claims 1 to 3, since the current sensor does not drop the voltage of the circuit due to its nature, it does not affect the performance of the electric driver at all. There is.

According to the second or third aspect of the present invention, the operation of the electric screwdriver can be detected by an alternating current without knowing the movement of the electric screwdriver, the completion of tightening the screws can be detected, and the number of tightening screws can be further determined. You can check the tightening of screws more accurately because you can count accurately.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a method for confirming completion of screw tightening of an electric screwdriver and a confirmation device for completion of screw tightening of an electric screwdriver according to the present invention.

FIG. 2 is a block diagram showing a configuration of a circuit in an embodiment of a method for confirming completion of screw tightening of an electric screwdriver and an apparatus for confirming completion of screw tightening of an electric screwdriver according to the present invention.

[Explanation of symbols]

1 Current converter 2 current control circuit 3 Peak value detection circuit 4-hour setting circuit 5 Tightening frequency setting circuit 6 Tightening frequency display circuit 7 Tightening failure display circuit

Claims (3)

[Claims] 1. A method of tightening a screw with an electric screwdriver, wherein a change in a current value at the time of starting and locking an alternating current flowing through the electric screwdriver is detected to confirm that the screw tightening is completed. How to confirm the completion of screw tightening of the electric screwdriver. 2. The screw tightening of an electric screwdriver, wherein the screw tightening is confirmed by the method according to claim 1, the number of continuous tightening is set in advance, and the tightening is confirmed by comparing and judging. How to confirm completion. 3. A commercial power supply circuit for driving an electric driver is provided with a current converter, which has a counter for counting the number of times a peak value appears within a certain period of time and for setting and comparing the number of tightening screws within a certain cycle. Confirmation device for screw tightening of electric screwdriver