JPH0661467U - Electric driver control device - Google Patents

Abstract

(57) [Abstract] [Purpose] Even when the switch operation is set to low torque, it is possible to effectively prevent the motor operation from stopping due to a malfunction at startup. [Structure] A comparison circuit 3 compares the signal values output from the triangular wave generation circuit 1 and the slow start circuit 2, respectively.
Then, when the signal value output from the triangular wave generation circuit 1 is smaller than the signal value output from the slow start circuit 2, a predetermined constant voltage is output from the comparison circuit 3. When the signal output from the comparison circuit 3 and the signal output from the brake circuit 4 when the limit switch S ₂ is off are input at the same time, a predetermined signal whose output time gradually increases is output to the motor 7. As a result, the drive time to the motor 7 gradually increases, whereby the rising speed of the motor 7 gradually increases, and the increase in inertia (reaction force) at the time of startup is suppressed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an automatic screw tightener that rotates a bit by the driving force of a motor and tightens a screw by the rotating force of the bit. Particularly, the screw tightening that suppresses the rotation of the motor to a low level immediately after the driving is started (started) is performed. The present invention relates to a control device for an electric driver that is enabled.

[0002]

[Prior art]

 In an automatic screw tightener that tightens the screw with the driving force of the motor, the completion of the screw tightening operation is detected by detecting the reaction that occurs when the screw is completely tightened, and the motor is stopped. Therefore, the allowable torque is set. Therefore, when a torque exceeding this is applied, the limit switch is activated to stop the power supply to the motor, thereby protecting the motor.

By the way, in such an automatic screw tightening machine, along with downsizing and precision of various devices in recent years, downsizing of screws to be used and drastic reduction of set value of tightening torque are demanded. As a result, a torque control value that is kept low has been studied and developed.

[0004]

[Problems to be solved by the device]

 However, in such an automatic screw tightener, when the internal structure, for example, the thrust load receiving mechanism, the bit holder, and the rotating mechanism such as the bit have a large mass, the inertial force in the rotating direction of the bit also increases accordingly. Become. As a result, if the motor start-up speed is high, the set torque will be reached at startup, and the limit brake will operate, causing the motor to automatically stop, which is a problem.

Therefore, for example, it is considered to reduce the weight of the rotating mechanism in order to suppress the inertial force at the time of startup, but there is a limit in consideration of strength and the like, and it is not an effective solution. .

Therefore, in view of the above-mentioned circumstances, the present invention effectively prevents the motor from stopping due to a malfunction at the time of start-up, even when the limit switch is set to operate at a low torque. It is an object of the present invention to provide a control device for an electric driver capable of performing the above.

[0007]

[Means for Solving the Problems]

 That is, the present invention has a triangular wave generating circuit which outputs a predetermined triangular wave, a slow start circuit which outputs a linear primary signal wave, and an output voltage value V from the triangular wave generating circuit. ₁ And the output voltage value V of the slow start circuit₂Compare with₁Is V₂When a limit circuit that turns on the comparator circuit that outputs a predetermined voltage and an external force that exceeds the set torque is applied to the bit within the following time and detects this when the bit and drive motor are turned on, It is equipped with a brake circuit that outputs the signal from the AND circuit, and an AND circuit that outputs the signal to the motor when the signal from this brake circuit and the signal from the comparison circuit are output at the same time. It is configured to output to the driving motor.

[0008]

[Action]

 In this invention, the comparison circuit compares the signal values output from the triangular wave generation circuit and the slow start circuit, respectively. Then, when the signal value output from the triangular wave generation circuit is smaller than the signal value output from the slow start circuit, a predetermined constant voltage is output from the comparison circuit. If the signal output from this comparison circuit and the signal output from the brake circuit when the limit switch is off are input at the same time, a predetermined signal with a gradually increasing output time is output to the motor to drive it. The time gradually increases, which gradually increases the motor start-up speed and suppresses the increase in torque at startup.

[0009]

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an electric driver control device according to the present invention. This control device includes a triangular wave generation circuit 1, a slow start circuit 2, a comparison circuit 3, a brake circuit 4, and an AND circuit 5. , Switch means 6.

In the figure, reference numeral 7 is a bit (not shown) driving motor, 8 is a brake resistor for dynamic braking, 9 is a diode for giving a flywheel effect to the bit, and 10 is dynamic braking. It shows a thyristor for.

The triangular wave generation circuit 1 is composed of a start switch S ₁ operated by a worker with a button at the start of work, an oscillation circuit 11 using an astable multivibrator, and an integration circuit 12. The rectangular wave (or square wave) output from the oscillation circuit 11 is input to the integration circuit 12, and the triangular wave (sawtooth wave) signal V ₁ shown in FIG. 3 is generated. The output terminal of the triangular wave generating circuit 1 is connected to one input terminal of the comparator 3.

[0012] Slow start circuit 2, a variable resistor R _1, a capacitor C, is composed of a variable resistor R ₂ Metropolitan of dividing, which exponent signal (hereinafter showing a waveform as shown in FIG. 2 V _{2 (} which is called a function waveform) is generated. The exponential waveform V ₂ of the Surosuta over preparative circuit 2, the curve shown in the graph of V ₂ -2 when when a large capacitance of the capacitor C the graph of V ₂ -1, also a small capacitance value of the capacitor C As shown in FIG. 3, when the capacitance value of the capacitor C exceeds a certain value and is large, it changes substantially linearly (linearly first order). The variable resistor R ₁ is adapted to initialize the rising angle θ of the exponential function waveform, and the variable resistor R ₂ divides the voltage output to the other terminal of the comparison circuit 3 to divide the voltage of the motor 7. It is designed to adjust the maximum speed.

As shown in FIG. 3, the comparison circuit 3 outputs a predetermined voltage V ₃ when the output voltage value V ₁ from the triangular wave generation circuit ₁ is smaller than the output voltage value V ₂ of the slow start circuit 2. The output time of this output voltage signal gradually increases. As a result, the output time of the signal output to the motor 7 via the AND circuit 5 and the switch means 6 gradually increases, and the slow start operation in which the rising speed of the motor 7 also gradually increases is realized. There is.

The brake circuit 4 is connected to a limit switch S ₂ having a mechanical structure that detects when an external force exceeding the set torque acts on the bit and stops the power supply to the motor 7. The output signal when the limit switch S ₂ is turned on (set operation) is configured so that Q is H and [outer 1] is L.

[0015]

[Outer 1]

The AND circuit 5 has an input terminal connected to the output terminal of the comparison circuit 3 and an output terminal of the brake circuit 4, and an output terminal connected to the base electrode (B) of the transistor which is the switch means 6. Therefore, when output signals from both sides are input, a predetermined signal is output.

In the transistor that is the switch means 6, the collector electrode (c) is connected to the cathode of the SCR 10, the anode terminal of the diode 9 and one end of the motor 7, and the emitter electrode (E) is grounded. .

Therefore, according to this embodiment, when the start switch S ₁ is turned on, the output time to the motor 7 is gradually increased. A start can be realized. As a result, there is no risk of a sudden load being applied to the rotary system of the bit at startup, and even if the allowable torque setting value is greatly reduced, the limit switch will operate and the drive operation of the motor 7 will stop. Can be effectively prevented.

[0019]

[Effect of device]

 As described above, according to this invention, the comparison circuit compares the signal values output from the triangular wave generation circuit and the slow start circuit, respectively. Then, when the signal value output from the triangular wave generation circuit is smaller than the signal value output from the slow start circuit, a predetermined constant voltage is output from the comparison circuit.

When the signal output from this comparison circuit and the signal output from the brake circuit when the limit switch is off are input at the same time, a predetermined signal whose output time gradually increases is output to the motor, The drive time to the motor gradually increases, which gradually increases the motor start-up speed and suppresses the increase in torque at startup.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing a control device according to the present invention.

FIG. 2 is a graph showing an output waveform from a slow start circuit.

FIG. 3 is a graph showing an output state of a voltage signal output from a comparison circuit.

[Explanation of symbols]

1 triangular wave generation circuit 2 slow start circuit 3 comparison circuit 4 brake circuit 5 AND circuit 6 switch means S ₂ limit switch

Claims (1)

[Scope of utility model registration request] 1. A triangular wave generating circuit for outputting a predetermined triangular wave, a slow start circuit for outputting a linear first-order signal wave, the output voltage value of the output voltage value V ₁ and the slow-start circuit from the triangular wave generating circuit V ₂ And a comparison circuit that outputs a predetermined voltage within the time when V ₁ is V ₂ or less, and when an external force exceeding the set torque acts on the bit, this is detected to supply power to the bit and the driving motor. When a limit switch for stopping the is turned on, a brake circuit that outputs a predetermined signal, and an AND circuit that outputs a signal to the motor when a signal from the brake circuit and a signal from the comparison circuit are simultaneously output, An electric driver control device characterized in that an output signal from the AND circuit is output to a bit driving motor.