JP4132161B2 - Electric tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric tool for fastening a bolt or the like with a motor.
[0002]
[Prior art]
As an example, a series motor (hereinafter referred to as a motor) is used for an electric tool that uses the rotational torque of a motor, such as a bolt fastening machine, and 100 V or 200 V is used as a power supply voltage for driving the motor. . In actual use, the power outlet is often separated from the work place, and an extension cable is used.
[0003]
[Problems to be solved by the invention]
At this time, if the extension cable is too long, the voltage drop due to the extension cable may be insignificant in the operation of the power tool. In this case, the motor of the electric tool becomes insufficient in torque or defective in rotation, resulting in a problem that the quality of work using the electric tool is lowered. In addition, the conventional power tool does not employ a configuration for notifying the operator of such a low voltage state, and even if the tightening state is poor due to a power supply voltage drop or the like, the operator recognizes the state. There is a bug that you can not.
[0004]
The present invention has been made in order to solve the above-described problems, and its object is to provide a power supply voltage lower than the specification to an electric power tool having a predetermined power supply voltage specification so that the low voltage state can be determined by an operator. Provide a power tool that can improve the quality of work and provide a power tool with significantly improved usability by allowing the operator to easily recognize the low voltage state of the power supply voltage. That is.
[0005]
[Means for Solving the Problems]
In the electric tool according to the first aspect of the present invention, a motor that generates rotational torque, a motor drive unit that drives the motor, a voltage detection unit that detects a power supply voltage applied to the electric tool via a power cable, and a display And a control unit to which the notification unit is connected. In the electric tool, the voltage detection unit has a first voltage that is the power supply voltage immediately before starting the motor, and a tightening torque has a predetermined torque value. And detecting the second voltage that is the power supply voltage when the work is completed, and the control unit stores the first voltage and the second voltage detected by the voltage detection unit, and after the work is completed, the second voltage is detected. One voltage and the second voltage are alternately displayed on the display unit, and the voltage difference between the first voltage and the second voltage detected by the voltage detection unit or the second voltage is predetermined. If it is outside the voltage range, Characterized in that to perform intellectual operation.
In the invention of claim 2, in addition to the invention of claim 1, the control section can select whether or not to display the first voltage and the second voltage on the display section after the work is completed. It is characterized by.
Therefore, according to the first aspect of the present invention, when the power tool is used, the power supply voltage when the current flows is lower than the power supply voltage before the current for driving the motor flows by using an extension cable or the like. Even when the resulting voltage drop is not negligible for the operation of the electric tool, the operator can recognize the degree of the voltage drop by the alternate display of the first voltage and the second voltage, thereby improving the work quality. be able to.
[0006]
In addition , when the voltage drop described above is not negligible in the work quality of the power tool, the power tool notifies the worker of this, so the worker can easily recognize the low voltage state of the power supply voltage, and the usability is improved. Greatly improved.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to examples.
[0008]
1 to 4 show an embodiment of the present invention. FIG. 1 is a block diagram showing an electrical configuration of a bolt and nut fastening machine (hereinafter referred to as a fastening machine) 1 according to an embodiment of the present invention, FIG. 2 is a perspective view of the fastening machine 1, and FIG. FIG. 4 is a flowchart for explaining the operation of another embodiment of the present invention. Hereinafter, the configuration of the fastening machine 1 will be described with reference to FIG.
[0009]
The fastening machine 1 includes a substantially cylindrical main body 2, a fastener 3 attached to one end of the main body 2, and a grip 4 formed integrally with the other end of the main body 2. . A motor such as a universal motor and a speed conversion mechanism (both not shown) are built in the main body 2. The grip portion 4 is formed so that an operator can hold it with a hand, and a trigger-like power switch 5 is disposed at a position where a finger is positioned in the holding state. In the vicinity of the power switch 5, a lock switch 6 is provided for fixing a state where the trigger-shaped power switch 5 is pulled. In the vicinity of the grip portion 4 of the main body 2, a changeover switch 7 for switching the rotation of the motor, and hence the rotation of the fastener 3, between a predetermined forward rotation and a reverse rotation is disposed. An input dial 8 for inputting a tightening condition value such as a maximum torque value and a maximum rotation angle at the time of bolt tightening is provided on the top of the main body 2, and is set near the input dial 8. A display unit 9 is provided for displaying input conditions such as a maximum torque value and a maximum rotation angle, or displaying a power supply voltage as described later. A power cable 10 is connected to the tip of the grip portion 4.
[0010]
Hereinafter, the electrical configuration of the fastening machine 1 will be described with reference to FIG. Fastening device 1 comprises a control power supply unit 13 connected via a power supply switch 5 from the commercial AC power source 12 and the power supply line 19 in the fastening device 1, the driving voltage is supplied from the control power supply unit 13, the fastening device 1 As a control unit , a microcomputer (hereinafter referred to as a microcomputer) 15 having a built-in memory 11 is provided. A voltage detector 14 is connected to the power line 19 and detects a power supply voltage supplied via the power cable 10. An output from the microcomputer 15 for driving the motor 16 is output to the power unit 18 via an interface circuit (hereinafter referred to as I / F circuit) 17. The power unit 18 is interposed in the power supply line 19 and includes a triac or the like, and is based on a drive control signal that is phase-modulated at a phase angle corresponding to a preset motor rotational speed as an example from the I / F circuit 17. Then, the stator (not shown) of the motor 16 is turned on / off. The motor 16 is rotationally driven at a predetermined rotational speed by the on / off operation of the power unit 18.
[0011]
The power line 19 is provided with a motor current detection circuit 20 such as a current transformer as an example, detects the current flowing through the motor 16, and the detected current value is input to the microcomputer 15. By detecting the motor current with the motor current detection circuit 20, the magnitude of the load of the motor 16, that is, the torque of the motor 16 can be detected. Further, the rotation of the motor 16 is detected by a rotation angle detecting element such as a pulse generator, for example, and the detected rotation angle data is input to the microcomputer 15, and the microcomputer 15 determines the motor 16 based on the rotation angle data. The rotation is controlled at the rotation speed. Further, the microcomputer 1 5 and the memory 11 are provided, a plurality of types of data to be described later is stored. Further, the microcomputer 1 5, setting unit 21 is connected. The setting unit 21 is data input means including the change-over switch 7 and the input dial 8, and the operation state of the fastening machine 1 is set to a normal normal operation mode for tightening and a voltage display mode for checking a power supply voltage. Switching input to switch between is also performed. Further, the buzzer 22 is connected to the microcomputer 15 as a notification means for notifying the worker when the power supply voltage is low as described later. However, the notification means is not limited to the buzzer 22.
[0012]
Hereinafter, the operation of the fastening machine 1 according to the present embodiment will be described with reference to FIG. In the following description, when tightening the bolt, a desired tightening torque value is input using the input dial 8. When the bolt is tightened, the fastening machine 1 is first tightened until the set torque value is reached. The operator sets a predetermined power supply voltage value to be used prior to the operation of tightening the bolt. When the power switch 5 of the fastening machine 1 is operated to switch from the off state to the on state, the voltage detection unit 14 sets the power supply voltage from the connected power supply 12 to the first before the rotation of the motor 16 in step a1. The voltage is read and stored in the memory 11 of the microcomputer 15.
[0013]
In step a2, the motor 16 is rotationally driven. In step a3, it is determined whether or not the motor current detected by the motor current detection circuit 20 has reached a predetermined current value, and until the predetermined current value is reached, that is, until the bolt or nut has a predetermined torque value. Tightening is performed. When the tightening torque reaches a predetermined torque value in step a3, the voltage detection unit 14 reads the power supply voltage at that time as the second voltage in step a4 and stores it in the memory 11 of the microcomputer 15. Next, in step a5, the control of the power unit 18 is stopped, and the motor 16 is stopped.
[0014]
In step a6, the microcomputer 15 reads the first voltage and the second voltage from the memory 11, and alternately displays them on the display unit 9. By confirming this display, the operator compares the first voltage, which is the power supply voltage in a state in which no driving current flows through the fastening machine 1, with the second voltage in a state in which the driving current flows through the fastening machine 1. can do. The data of the first voltage and the second voltage used for such alternate display may be erased from the memory 11 when the alternate display ends after the alternate display is continued for a predetermined period, or the alternate display Regardless of the presence or absence, the next tightening operation may be started and stored in the memory 11 until the first voltage is read by the microcomputer 15.
[0015]
In this embodiment, when supplying the power supply voltage to the fastening machine 1, an extension cable is used when the power outlet is located away from the work place. However, if this extension cable is long, a voltage drop occurs. This voltage drop can be confirmed as a difference between the first voltage and the second voltage. Therefore, the operator can easily determine whether the voltage drop amount or the value of the second voltage, which is a voltage in a state where the voltage has dropped, is within the range of appropriate use conditions set in the fastening machine 1 in advance. Can be judged. As a result, even if the tightening work is inappropriate due to the use of an extension cable that is too long or the power supply voltage of the AC power supply 12 being lowered, etc. It can be interrupted to deal with power supply voltage drop, change the extension cable to a short cable, or retighten tightened bolts and nuts, etc., and improve workability, tightening work quality and usability. Can be significantly improved.
[0016]
As another embodiment of the present invention, an appropriate voltage range that is the appropriate use condition is set in the microcomputer 15 in advance, or an operator sets the setting unit 21 in the fastening machine 1 before use. An example in which an appropriate voltage range is set in the microcomputer 15 can be employed. At this time, the microcomputer 15 compares the voltage difference between the first voltage and the second voltage, or the second voltage itself, with the appropriate voltage range at the stage where the processing proceeds from the steps a1 to a4. If the microcomputer 15 determines that the voltage difference or the second voltage is outside the appropriate voltage range, the microcomputer 15 sounds the buzzer 22. As a result, the operator can recognize the decrease in the power supply voltage and the decrease in the drive voltage due to the use of the extension cable that is too long, even during the tightening operation, and the various types as described in the first embodiment. The measures can be taken promptly, and the workability, tightening work quality and usability are greatly improved.
[0017]
As still another embodiment of the present invention, when performing the tightening operation instead of the operation of alternately displaying the first voltage and the second voltage at the end of the normal tightening operation as described above, When the normal operation mode is set using the setting unit 21 in FIG. 1 to perform tightening and the power supply voltage such as the first voltage or the second voltage is displayed, the voltage display mode is set using the setting unit 21. An example using a configuration for setting and displaying is possible. Such a configuration provides setting means such as a switch for selectively setting the normal operation mode and the voltage display mode, and temporarily stores the data of the first voltage and the second voltage stored in the memory 11. As described above, until the next tightening operation is started, when the voltage display mode is set, the microcomputer 15 stores the memory 11 in the memory 11 as described in the first embodiment. It implement | achieves by performing the control which reads the 1st voltage and 2nd voltage which are memorize | stored alternately, and displays on the display part 9 alternately.
[0018]
The operation is shown in the flowchart of FIG. Hereinafter, the present embodiment will be described with reference to FIGS. 1 and 2 together. In this embodiment, in order to perform the tightening operation, the setting unit 21 shown in FIG. 1 sets the operation mode of the fastening machine 1 to the normal tightening operation including the operation of the first embodiment or the second embodiment. Set the normal operation mode to be performed. At this time, the microcomputer 15 determines whether or not the voltage display mode is selected by the setting unit 21 in step b6 at the stage where the processing is advanced to steps b1 to b5 similar to steps a1 to a5. When the voltage display mode is set in step b6, the first voltage and the second voltage as described above are alternately displayed in step b7, and then the process ends. If the voltage display mode is not set in step b6, the process ends without performing the alternate display of the voltage.
[0019]
In such an embodiment, in addition to the effects described in the first embodiment, by setting the voltage display mode, not only at the end of the tightening operation but also until the next tightening operation is performed. Can be displayed at any timing. Therefore, when the operator needs to repeatedly check the degree of decrease in the power supply voltage supplied to the fastening machine 1, or as an example, an operation explanation person of the manufacturer of such a fastening machine 1 It can be suitably used when explaining an environmental condition such as a power supply voltage at a site where 1 is newly used to an actual worker. Therefore, usability is further improved.
[0020]
In addition, it is obvious that the present invention includes embodiments in which the above embodiments are combined.
[0021]
The power tool of the present invention is not limited to the fastening machine 1 of each of the embodiments described above, and is widely implemented for a wide variety of power tools that use the rotational torque of the motor.
[0022]
The configurations and operations of the above-described embodiments are examples of the present invention and do not limit the present invention. The present invention includes wide variations without departing from the spirit of the present invention.
[0023]
【The invention's effect】
As described above, in the first aspect of the present invention, the voltage detection unit detects the first voltage immediately before starting the motor of the power supply voltage applied to the motor and the second voltage at the completion of the work. The control unit stores each voltage detected by the voltage detection unit and causes the display unit to alternately display the first voltage and the second voltage when the operation is completed.
[0024]
Therefore, when using the power tool, the voltage drop of the power tool when the current flows becomes lower than the power voltage before the current for driving the motor, such as by using an extension cable. Even when the operation cannot be ignored, the operator can recognize the degree of the voltage drop by the alternate display of the first voltage and the second voltage, and the work quality can be improved.
[0025]
The electric power tool includes a notification unit connected to the control unit. The control unit causes the notification unit to perform a notification operation when at least one of the first voltage or the second voltage detected by the voltage detection unit is lower than a predetermined reference voltage.
[0026]
As a result, when the voltage drop described above is not negligible in the work quality of the power tool, the power tool notifies the worker of this, so the worker can easily recognize the low voltage state of the power supply voltage, and the usability Is greatly improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an electrical configuration of a fastening machine 1 according to an embodiment of the present invention.
FIG. 2 is a perspective view of the fastening machine 1;
FIG. 3 is a flowchart showing an operation example of the fastening machine 1;
FIG. 4 is a flowchart showing another example of operation of the fastening machine 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fastening machine 9 Display part 10 Power cable 11 Memory 12 Commercial alternating current power supply 13 Control power supply part 14 Voltage detection part 15 Microcomputer 16 Motor 20 Motor current detection circuit 21 Setting part 22 Buzzer

Claims (2)

A motor that generates rotational torque;
A motor drive unit for driving the motor;
A voltage detector that detects a power supply voltage applied to the electric tool via the power cable;
A control unit to which the display unit and the notification unit are connected;
In the electric tool with
The voltage detection unit detects a first voltage that is the power supply voltage immediately before the start of the motor and a second voltage that is the power supply voltage at the completion of the operation in which the tightening torque becomes a predetermined torque value,
The control unit stores the first voltage and the second voltage detected by the voltage detection unit, and alternately displays the first voltage and the second voltage on the display unit after completion of work,
When the voltage difference between the first voltage and the second voltage detected by the voltage detection unit or the second voltage is outside a predetermined voltage range, the notification unit is caused to perform a notification operation. An electric tool characterized by   2. The electric tool according to claim 1, wherein the control unit can select whether or not to display the first voltage and the second voltage on the display unit after the work is completed.

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