JP2008025252A - Method of preventing twisting-off of wire in reinforcement binding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of preventing twisting-off of a wire in a reinforcement binding machine which can monitor a twisting state of the wire, automatically terminates twist-fastening before the wire is twisted off, and positively binds reinforcements without twisting off the wire. <P>SOLUTION: The method of preventing twisting-off of the wire in the reinforcement binding machine which functions to bind the reinforcements a with the wire 1, is characterized by provision of the following requirements. (A) A driving torque of a motor 6 for rotationally driving a hook 9 for gripping the wire 1 that binds the reinforcements a is measured by a driving current, and when a measured rate of change Ad of the driving torque becomes smaller than a predetermined rate of change Ae, the motor 6 is stopped to terminate the twist-fastening of the wire by a twisting device 4. (B) The measurement is carried out either by starting monitoring of the rate of change Ad of the driving torque when a predetermined time period T has elapsed since the start of the twisting, or when the driving torque has reached a predetermined value Ma or more. Alternatively the measurement is carried out by starting the monitoring, based on both factors taken into consideration. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wire thread breakage prevention method in a reinforcing bar binding machine.

Conventionally, when constructing reinforced concrete in a building or a structure, concrete is placed after binding reinforcing bars crossed vertically and horizontally with wires, but binding of reinforcing bars with wires is performed by a reinforcing bar binding machine. Wire binding by this reinforcing bar binding machine requires that the reinforcing bars be securely bound while preventing thread breakage of the wire, and a method for preventing wire thread breakage for this purpose has been proposed by the present applicant (for example, Patent Document 1). This rebar binding machine measures the drive torque after the motor that rotates the hook that grips the wire rotates by the drive current every unit time, and when the change rate of the drive torque switches from increase to decrease, The torsional tightening by the twisting device is terminated.
Japanese Patent No. 3227693

  The problem to be solved by the present invention is that the change rate of the drive torque changes from increase to decrease means that the twist of the wire has reached the peak, and there is inertia even if the motor is stopped at that time There was a problem that the bundling progressed and the wire was broken.

  The present invention solves the above-mentioned problems, monitors the twisting state of the wire, automatically ends the twisting before the wire breakage occurs, and does not cause the wire breakage. It is an object of the present invention to provide a method for preventing wire breakage in a reinforcing bar binding machine that can reliably perform binding.

In order to solve the above-mentioned problems, a method for preventing wire breakage in a reinforcing bar binding machine according to the present invention is characterized in that the reinforcing bar binding machine for binding reinforcing bars with a wire has the following requirements.
(A) The driving torque of the motor that rotationally drives the hook that holds the wire that binds the reinforcing bars is measured by the driving current, and when the change rate of the driving torque becomes smaller than the predetermined change rate, the twisting by the twisting device is performed. End of tightening (b) Either the monitoring of the change rate of the driving torque is started after a predetermined time has elapsed from the start of twisting, or is started after the driving torque exceeds a predetermined value, or Note that the drive torque of the motor is measured every unit time, and the rate of change of the drive torque is monitored based on the torque measured every unit time and the torque measured a predetermined number of times ago. The torsional tightening by the torsion device may be terminated when the monitored change rate becomes smaller than a predetermined change rate.

  In addition, the drive torque of the motor is measured every unit time, and the first change rate of the drive torque is monitored based on the torque measured every unit time and the torque measured before the first predetermined number of times. Then, the second change rate of the driving torque is monitored based on the torque measured before the second predetermined number of times less than the first predetermined number of times, and the first change rate is smaller than the predetermined change rate. The torsional tightening by the twisting device may be terminated when the second change rate becomes negative.

  According to the first aspect of the present invention, it is possible to realize a method for preventing wire breakage in a reinforcing bar binding machine that can reliably bind wires by a wire without causing thread breakage of the wire.

  According to the invention of claim 2, since the time interval for calculating the rate of change of the driving torque of the motor is calculated while being shifted by a time shorter than this time interval, the rate of change is calculated at regular time intervals. Compared to the above, the rate of change in torque can be closely monitored, and the wire can be bound without failing without causing wire breakage.

  According to the invention of claim 3, the first rate of change of torque is calculated at a relatively long first time interval, and the torque is calculated at a short second time interval set at the end of the first time interval. Since the second rate of change is calculated, the binding status can be monitored with the first rate of change and the second rate of change, and the binding can be terminated when the binding is sufficient. It is possible to realize a method for preventing wire breakage in a reinforcing bar binding machine that is stronger and does not cause wire breakage.

  FIG. 1 shows a main part of an example of a reinforcing bar binding machine according to the present invention. The reinforcing bar binding machine has a wire feeding device 2 that feeds a wire 1 wound around a spool 7 forward, and a sent wire 1. A guide arm 3 for winding the wire 1 in a loop, a twisting device 4 for gripping and twisting a part of the wound wire 1, and a cutting device 5 for dividing the wire loop from the original wire 1. The wire feeding device 2, the twisting device 4, and the cutting device 5 are provided in the binding machine body and are operated by the motor 6.

  In this reinforcing bar binding machine, the main switch 14 is inserted, and when the reinforcing bar a is bound, the trigger lever 8 is pulled and the trigger switch 12 is turned on, whereby the wire 1 is sent out from the spool 7 by the wire feeder 2 and the guide arm After the wire 3 is wound around the reinforcing bar a in a loop shape, the twisting device 4 is actuated, and a part of the wire loop 1a is gripped by the hook 9 and twisted and rotated to bind the reinforcing bar a, and the cutting device 5 The wire loop 1a is cut from the original wire 1 and divided.

  By the way, in this reinforcing bar binding machine, the measuring means 10 for measuring the torque of the motor 6 of the torsion device 4 and the control for judging the binding end timing from the torque measured by the measuring means and stopping the motor 6 to end the binding. Means 11 are provided.

  FIG. 2 shows a block diagram of a reinforcing bar binding machine, wherein reference numeral 10 is a measuring means, 11 is a control means, 12 is a trigger switch, 13 is a battery pack, 14 is a main switch, and 15 is a control for the voltage supplied from the battery pack. Fig. 2 shows a DC-DC converter which converts the voltage to actuate the means.

  The measuring means 10 is connected in series to the motor 6 and measures the driving current of the motor 6, and the change in torque of the motor 6 can be monitored by measuring the driving current. The measuring means 10 is composed of a resistance element, and the drive current flowing through the circuit is obtained from the terminal voltage of the resistance element. The measuring means 10 may use a Hall element type current sensor or the like that obtains a driving current by measuring a magnetic flux generated by a current flowing through the circuit. A measurement result d measured by the measuring means 10 is input to the control means 11.

  The control means 11 is composed of a microprocessor, and monitors a change in torque of the motor 6 based on a control program resident in a built-in memory, and controls a switching element (for example, a voltage applied to the stator coil of the motor). The power transistors 16a to 16d are configured to control the drive signals e1 to e4 to control the rotational speed, operation, and stop of the motor 6.

  Based on the timer signal t from the timer circuit 17, the control means 11 measures the change in the current flowing through the motor 6 and the past (the unit time T1 is several). The rate of change in torque is monitored from the drive current value measured retroactively.

  This control means 11 monitors that the torque of the motor 6 for twisting the wire increases as the torsional tightening of the reinforcing bar by the wire becomes harder. In this monitoring, the drive current value is measured every unit time T1, and the change rate of the torque (drive current value) is monitored from the previously measured drive current value, and the change rate becomes smaller than the predetermined change rate. Thus, it is determined that the reinforcing bars are sufficiently bound, and the motor 6 is stopped by switching the drive signals e1 to e4 of the motor 6.

  As shown in the motor drive current characteristic curve of FIG. 3, the criterion for determining that the binding is sufficient is that when the wire starts to break, the characteristic curve becomes gentle and the motor 6 is rotated as it is. If the wire continues to be twisted, the wire will eventually be broken, and if the wire is broken, the load on the motor 6 will disappear and the drive current will decrease rapidly, so the rate of change immediately before the rate of change of the drive current becomes zero. May be set as a predetermined rate of change.

  It should be noted that if the user decides that it is better not to cause the thread to break even if the rebar binding is somewhat weak, and that it is better to have stronger rebar bundling even if some of the wires break off. Since there may be cases where it is not possible to determine this rate of change in a general manner, it is possible to change the size of the rate of change with a setting dial (not shown). The change rate may be changed by turning the setting dial.

  According to the wire thread breakage prevention method in the above-described reinforcing bar binding machine, a part of the wire loop 1a wound around the reinforcing bar crossing portion is gripped by the hook 9, and the hook 9 is rotated and twisted by rotating the motor 6. When monitoring, the timing at which the rate of change in torque (drive current) of the motor 6 becomes smaller than the predetermined rate of change is monitored, and the motor 6 is stopped at this point to bind the wires in a sufficiently twisted and tightened state. This can not only ensure that the torsional tightening is performed, but also terminate the binding before the wire is threaded.

  Since the torque change rate does not always change smoothly depending on the thickness of the reinforcing bar or the number of wires, there is a possibility that a plurality of the same change rate V may occur, and even if the predetermined change rate is reached, the binding is surely performed. Since there are cases where this is not done, the time to start monitoring the rate of change is set separately. As shown in FIG. 3, the monitoring start time starts from the time when the condition of either one or both of the time T when the torsion progresses and the torque change rate is determined to be large and the torque Ma is cleared. Monitoring is started.

  As a result, since the curve begins to wind gradually and the torsion progresses and the torque increases, the change in the curve increases, and as the bundling progresses, the curve changes gently again. The binding is not terminated only by looking at the rate of change A, and if the rate of change A after the torque exceeds the predetermined value Ma is seen and the binding is terminated, the wire is incompletely tightened. In such a case, the bundling will not end.

  Next, the wire thread breakage prevention method of the above-described reinforcing bar binding machine will be described based on the flowchart in FIG. 4 and the time chart in FIG.

  The trigger button is pulled to rotate the motor, measure the torque every unit time, and monitor the elapsed time from the start of rotation (step ST1). It is determined whether the torque exceeds a predetermined value Ma or a predetermined time has passed (step ST2), and if it exceeds the set threshold value, the process proceeds to step ST3 and monitoring of the torque change rate is started.

  Torque is measured every unit time T1 (for example, 10 ms), and from the measured current torque M (n) and x (for example, five and the elapsed time T2 is 50 ms) before the torque M (nx). A torque change rate Ad is calculated (step ST4). In step ST5, the rate of change Ad is determined. If the rate of change Ad is smaller than the predetermined rate of change Ae, it is determined that twisting is sufficient, and the motor is stopped to stop twisting (step ST7).

  If the calculated rate of change Ad is greater than the set rate of change Ae, it is determined that the torsion is insufficient, and in step ST6, the counter is counted up, the process returns to step ST3, and after the next unit time T1 has elapsed. The torque M (n) is measured, the torque change rate Ad is calculated again in step ST4, and steps ST3 to ST6 are repeated until the torque change rate Ad is equal to or smaller than the predetermined change rate Ae.

  In the above-described thread breakage prevention method, the torque measurement time is sequentially shifted by unit time T1 (for example, 10 ms), and the torque measured for each unit time T1 and the unit time T1 are x (for example, five). The change rate of the torque is calculated with reference to the torque before the elapsed time T2 is 50 ms).

  That is, when calculating the torque change rate at the elapsed time T2 (for example, 50 ms), the torque change rate at the elapsed time T2 is calculated while shifting the elapsed time T2 by unit time T1 (for example, 10 ms). As shown in FIG. 6A, if the rate of change of torque is simply measured every elapsed time T2 (50 ms) as shown in FIG. 6A, the wire may be broken before the next measurement. However, by monitoring the change rate while gradually shifting the elapsed time T2, it is possible to recognize the predetermined change rate before the wire breakage occurs. Moreover, by setting the elapsed time to be larger than the unit time, it is possible to ignore the noise of torque change and lose the timing to capture the thread break in the time period until the next torque change rate is measured. This can be avoided. The unit time T1 described above is not limited to 10 ms, but may be set arbitrarily, such as 2 ms or 3 ms. The elapsed time T2 is not limited to five times the unit time T1, and may be set arbitrarily. That's fine.

  In the above-described twist-off prevention method, the torque change rate in the elapsed time is calculated while shifting the unit time. However, the change rate for each elapsed time and the change rate in a short time within the elapsed time are two. A method for monitoring one change rate and preventing twisting will be described with reference to the flowchart of FIG. 5 and the time chart of FIG.

  The trigger button is pulled to rotate the motor, measure the torque every unit time, and monitor the elapsed time from the start of rotation (step ST11). It is determined whether the torque threshold exceeds a predetermined value Ma or a predetermined time has elapsed (step ST12). If the threshold and the predetermined time have elapsed, monitoring of the torque change rate is started (step ST13).

  Torque is measured every unit time T1 (for example, 10 ms). From the measured torque M (n) and the torque M (nx) before the unit time is x (for example, five and the elapsed time is 50 ms). A torque change rate (first change rate) Ad1 when the first elapsed time T2 has passed is calculated (step ST14), and further y units (for example, 1 unit is 10 ms) before the unit time. A torque change rate (second change rate) Ad2 when the second elapsed time T3 has elapsed from the torque M (ny) is calculated (step ST15). In step ST16, the first change rate Ad1 is calculated. Is smaller than the predetermined change rate Ae or the second change rate Ad2 is negative, the motor is stopped and the torsion is stopped (step ST18).

  If the calculated first rate of change Ad1 is greater than the set rate of change Ae or the second rate of change Ad2 is not negative, it is determined that torsion is still incomplete, and the counter is incremented in step ST17. Returning to ST13, the torque M (n) after the elapse of the next unit time T1 is measured, the torque change rate is calculated again in steps ST14 and 15, and the torque change rate becomes a predetermined change rate. Steps ST13 to ST17 are repeated.

  In the above-described twist-off prevention method, the torque change rate is the second change rate shorter than the first change rate Ad1 in the first elapsed time T2 and the first elapsed time T2 set at the end of the first elapsed time. And the second rate of change Ad2 at the elapsed time T3, and the time when the first rate of change Ad1 becomes smaller than the predetermined rate of change Ae, or the second rate of change Ad2 When the rate of change Ad2 becomes negative, the motor is stopped to stop torsion.

  As a result, it can be seen that the twisting of the wire has reached its peak, and the motor can be stopped before all the wires are twisted, thus realizing a reinforcing bar binding machine capable of further binding. be able to. In the above-described reinforcing bar binding machine, the torque change rate has been described in terms of elapsed time, but it may be a twist angle instead of time. By doing so, there is an effect that is not affected by variations in performance of the battery and the motor.

Side view of a reinforcing bar binding machine to which the wire thread breakage prevention method according to the present invention is applied. Block diagram for explaining the electrical configuration of the reinforcing bar binding machine Drive current vs. time drive current characteristic diagram showing changes in motor drive current Flowchart for explaining a method for preventing wire thread breakage The flowchart figure explaining the other example of the thread breakage prevention method of a wire (A)-(c) is a time chart figure explaining the relationship between unit time and elapsed time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wire 4 Torsion apparatus 6 Motor 10 Measuring means 11 Control means Ad Rate of change of measured torque Ae Rate of change of predetermined torque T1 Unit time T2 Elapsed time

Claims (3)

In the reinforcing bar binding machine which binds a reinforcing bar with a wire, it has the following requirements, The wire threading prevention method in the reinforcing bar binding machine characterized by the above-mentioned.
(A) The driving torque of the motor that rotationally drives the hook that holds the wire that binds the reinforcing bars is measured by the driving current, and when the change rate of the driving torque becomes smaller than the predetermined change rate, the twisting by the twisting device is performed. End of tightening (b) Either the monitoring of the change rate of the driving torque is started after a predetermined time has elapsed from the start of twisting, or is started after the driving torque exceeds a predetermined value, or Measuring with both   The drive torque of the motor is measured every unit time, the change rate of the drive torque is monitored based on the torque measured every unit time and the torque measured a predetermined number of times before, and the change rate to be monitored is predetermined. The method of preventing thread breakage of a wire in a reinforcing bar binding machine according to claim 1, wherein the torsional tightening by the twisting device is terminated when the change rate becomes smaller than the change rate. The drive torque of the motor is measured every unit time, and the first change rate of the drive torque is monitored based on the torque measured every unit time and the torque measured before the first predetermined number of times, The second change rate of the drive torque is monitored based on the torque measured before the second predetermined number of times less than the first predetermined number of times, and the first change rate becomes smaller than the predetermined change rate. The method of preventing thread breakage of a wire in a reinforcing bar binding machine according to claim 1, wherein the torsional tightening by the twisting device is terminated at the time or when the second rate of change becomes negative.

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