JP3582333B2 - Brake mechanism of wire reel in rebar binding machine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a brake mechanism for stopping the rotation of a wire reel after sending out a binding wire of a predetermined length in a rebar binding machine.
[0002]
[Prior art]
In general, a reinforcing bar binding machine winds a binding wire of a predetermined length around a crossed rebar and twists the wire with a torsion hook to bind the wire. The wire is wound around a wire reel attached to the rear part of the binding machine main body. At the time of wire feeding, the wire is sent forward by wire feeding means. At this time, the wire reel rotates and the wire is unwound. The feed amount of the wire is precisely controlled, and when a predetermined length of wire is fed, the wire feed stops suddenly.
[0003]
[Problems to be solved by the invention]
However, according to the wire feed mechanism, when the feed of a predetermined length is performed, the feed of the wire is suddenly stopped, but the wire reel continues to rotate excessively due to inertia, so that the wire on the wire reel 20 as shown in FIG. Since the diameter of the wire 21 is expanded, the wire 21 is entangled and cannot be smoothly unwound, which may hinder the next wire feeding.
[0004]
As a countermeasure against this, it is conceivable to always apply a brake to the wire reel with a leaf spring or the like to prevent the coasting rotation of the wire reel, but in this case, the load of feeding increases, so the current consumption increases, The motor generates heat, causing problems such as a reduction in speed.
[0005]
SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a wire reel brake mechanism in a rebar tying machine capable of applying a brake to the rotation of the wire reel almost immediately after a predetermined wire feed is completed.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, a brake mechanism of a wire reel in a reinforcing bar binding machine according to the present invention includes a binding device that drives a binding wire by a feeding unit driven by a feeding motor from a wire reel rotatably provided at a rear portion of the binding machine body. In a wire reel brake mechanism of a rebar tying machine that wraps around a crossed rebar by sending out in front of the tying machine body,
At the center of the side surface of the wire reel, a concave portion having an inner peripheral surface formed in a polygonal shape is formed, and a brake shaft having an outer peripheral surface formed in a polygonal shape is engaged with this concave portion, and the brake shaft is connected to a brake motor. A fixed circuit fixed to the output shaft and a capacitor connected in series to this motor is provided, and a switch for switching the polarity of the motor and the capacitor is provided in this closed circuit,
At the time of wire feeding, the motor is connected to the closed circuit, and at the end of the wire feeding, the polarity of the motor is switched by the changeover switch, so that a reverse voltage is applied to the motor by the electric power stored in the capacitor at the time of wire feeding. And
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and 2 are a side view and a plan view, respectively, showing the outline of a reinforcing bar binding machine. In the figures, reference numeral 1 denotes a binding machine main body, and 2 denotes a wire reel rotatably provided at a rear portion of the binding machine main body 1. A passage (not shown) for the wire 3 is formed in the binding machine main body 1, a feeding means 5 for sending the wire 3 forward is arranged in the passage, and the wire 3 is formed in a loop shape at a front portion of the binding machine main body 1. A guide 6 is provided to guide the user to bend. Further, the binding machine body 1 is formed with a torsion hook 8 that engages with the wire 3 wound around the crossed reinforcing bar 7 and twists. The torsion hook 8 is configured to be driven by a motor 9. ing. The feeding means 5 is also driven by another motor (not shown).
[0008]
The rebar tying machine sends out a wire 3 of a predetermined length from the wire reel 2 by the feeding means 5 and winds the wire 3 around the crossed rebar 7, and the torsion motor 9 is operated based on a signal from the feeding means 5. It operates to drive the torsion hook 8 to twist and bind the wire 3.
[0009]
The wire reel 2 includes a drum 2a and a flange 2b, and is removably stored in a storage unit 10 formed on one rear side of the binding machine main body 1. The wire reel 2 is provided with the following brake mechanism. That is, as shown in FIG. 2, a recess 11 having an inner peripheral surface formed in a polygonal shape is formed at the center of the side surface of the wire reel 2, and a brake having an outer peripheral surface formed in a polygonal shape in this concave portion 11. The shaft 12 is engaged. The brake shaft 12 is fixed to an output shaft of the brake motor 13. Thereby, the motor 13 and the wire reel 2 are operatively connected.
[0010]
Next, as shown in FIG. 3, the brake motor 13 is provided with a closed circuit in which a capacitor C is connected in series, and the closed circuit is provided with a changeover switch sw for switching the polarity of the motor and the capacitor C. .
[0011]
In the above configuration, at the time of wire feeding, the motor is connected to a closed circuit by the switch sw as shown in FIG. When the wire 3 is fed by the wire feeding means 5, the brake shaft 12 also rotates because the wire reel 2 rotates, and the brake motor 13 is forcibly rotated in the same direction. The forcibly rotated brake motor 13 becomes a generator, and the generated power is stored in the capacitor C.
[0012]
When the feeding of a predetermined length of wire is completed, the CPU (Central Processing Unit) of the computer detects this and outputs a signal, and switches the switch sw based on this signal as shown in FIG. Since the polarity of the motor 13 is changed by this switching operation, a reverse voltage is applied to the motor 13 by the electric power stored in the capacitor C at the time of wire feeding, and the rotation of the wire reel 2 is braked to stop suddenly.
[0013]
As described above, almost simultaneously with the completion of the feeding of the wire 3 having the predetermined length, the brake means is operated to apply a brake to the wire reel 2 and the rotation thereof is suddenly stopped. The diameter of the wire 3 does not expand, and the wire 3 can always be smoothly fed, so that inconveniences such as an increase in current consumption, heat generation of the motor, and a decrease in speed in the conventional brake mechanism can be favorably prevented.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a side surface showing an outline of a reinforcing bar binding machine. FIG. 2 is a cross-sectional view of a plane showing an outline of the reinforcing bar binding machine. FIG. 3 is a closed circuit diagram of a motor constituting the brake mechanism. FIG. 5 is a circuit diagram showing a state in which the closed circuit is switched.
C capacitor sw switch 2 wire reel 3 binding wire 12 brake shaft 13 brake motor

Claims (1)

In a reinforcing bar binding machine that sends a binding wire forward from the binding machine body by a feeding means driven by a feeding motor from a wire reel rotatably provided at a rear portion of the binding machine body, and winds the binding wire around a crossed reinforcing bar to bind . In the wire reel brake mechanism ,
At the center of the side surface of the wire reel, a concave portion having an inner peripheral surface formed in a polygonal shape is formed, and a brake shaft having an outer peripheral surface formed in a polygonal shape is engaged with this concave portion, and the brake shaft is connected to a brake motor. A fixed circuit fixed to the output shaft and a capacitor connected in series to this motor is provided, and a switch for switching the polarity of the motor and the capacitor is provided in this closed circuit,
At the time of wire feeding, the motor is connected to the closed circuit, and at the end of wire feeding, by switching the polarity of the motor by the changeover switch, a reverse voltage is applied to the motor by the electric power stored in the capacitor at the time of wire feeding. > A brake mechanism for a wire reel in a reinforcing bar binding machine.

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