WO2008013142A1 - Method of preventing twisting off of wire in reinforcement bar binder - Google Patents

Abstract

In a reinforcement bar binder for binding reinforcement bars (a) by a wire (1), a method of preventing twisting off of the wire includes the following steps: (I) Measuring, with the use of a drive current of the motor (6), drive torque of a motor (6) for driving a hook (9) that holds the wire (1) for binding the reinforcement bars (a), and when the rate (Ad) of change in the measured drive torque is less than a predetermined rate(Ae) of change, stopping the motor (6) to stop twisting and fastening of the wire performed by a twisting device (4). (II) Performing the measurement by starting monitoring of the rate (Ad) of change of the drive torque at either or both of a time point when a predetermined time period (T) has passed after the start of twisting and a time point when the drive torque is greater than or equal to a predetermined value (Ma).

Description

 Specification

 Method for preventing wire thread breakage in reinforcing bar binding machine

 Technical field

 [0001] The present invention relates to a wire thread breakage prevention method in a reinforcing bar binding machine.

 Background art

 [0002] When constructing reinforced concrete in a building or a structure, the reinforcing bars that are crossed vertically and horizontally are bound by a shear, and then the concrete is placed. Reinforcing bars with wires is done with 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 has been proposed by the present applicant (for example, Patent Document 1). In this reinforcing bar binding machine, the drive torque after the motor that rotates the hook that grips the wire rotates is measured every unit time by the drive current, and the rate of change of the drive torque switches from increasing to decreasing. At that time, the torsional tightening by the twisting device is finished.

 Patent Document 1: Japanese Patent No. 3227693

[0003] In the above-described conventional reinforcing bar binding, the fact that the rate of change in driving torque changes from increasing to decreasing means that the torsion of the wire has reached its peak. For this reason, there was a problem that even if the motor was stopped at that time, there was an inertia and the binding proceeded and the wire was broken.

 Disclosure of the invention

 [0004] One or more embodiments of the present invention monitor the twisting state of a wire and automatically terminate the twisting before the wire breakage occurs, causing the wire to break. A method for preventing wire breakage in a reinforcing bar binding machine that can reliably perform binding without any problems is provided.

 [0005] According to one or more embodiments of the present invention, in the first aspect of the present invention, the wire thread breakage prevention method in the reinforcing bar binding machine includes the following steps.

(I) When the drive torque of the motor that rotates the hook that holds the wire that binds the reinforcing bars is measured by the drive current, and the rate of change of the drive torque becomes smaller than the specified rate of change End the torsional tightening by the torsion device at the point

 (II) Monitor the rate of change of the drive torque by measuring either one or both of the force that starts after a predetermined time has elapsed from the start of torsion, and the drive torque that starts when the drive torque exceeds a predetermined value.

 [0006] In the second aspect of the present invention, the drive torque of the motor is measured every unit time, and based on the torque measured every unit time and the torque measured a predetermined number of times before! Alternatively, the change rate of the drive torque may be monitored, and the tightening by the torsion device may be terminated when the monitored change rate becomes smaller than a predetermined change rate.

 [0007] Further, in the third aspect of the present invention, the drive torque of the motor is measured every unit time, and the torque measured every unit time and the torque measured before the first predetermined number of times The first change rate of the driving torque is monitored based on the second torque, and 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. Thus, when the first rate of change becomes smaller than the predetermined rate of change or when the second rate of change becomes negative, the torsional tightening by the twisting device may be terminated.

 [0008] According to the first aspect described above, the ability to realize a method for preventing wire breakage in a rebar binding machine that can reliably perform rebar bundling with wires without causing wire breakage. Touch with S.

 [0009] According to the second aspect, the time interval for calculating the rate of change in the driving torque of the motor is calculated while being shifted by a time shorter than this time interval, and therefore changes at regular time intervals. Compared with the case of calculating the rate, the rate of change of torque can be closely monitored, and the binding can be surely performed without causing the thread to break.

 [0010] According to the third aspect, the first change rate of the torque is calculated at a relatively long first time interval, and the short second time set at the end of the first time interval is calculated. Since the second rate of change in torque is calculated at intervals, the binding status is monitored based on the first rate of change and the second rate of change, and the binding is terminated when the binding is sufficient. Therefore, it is possible to realize a method for preventing wire thread breakage in a reinforcing bar binding machine that makes binding stronger and does not cause wire thread breakage.

[0011] Other features and advantages will be apparent from the description of the examples and the appended claims. Brief Description of Drawings

 FIG. 1 is a side view of a reinforcing bar binding machine to which a wire thread breakage preventing method according to an exemplary embodiment of the present invention is applied.

 [Fig. 2] Block diagram for explaining the electrical configuration of the reinforcing bar binding machine

 [Fig.3] Drive current vs. time drive current characteristic diagram showing changes in motor drive current

 FIG. 4 is a flowchart for explaining a method for preventing a wire from being broken.

 FIG. 5 is a flowchart for explaining another example of a wire thread breakage prevention method.

 [Fig. 6A] Time chart illustrating the case where the rate of change of torque is simply measured for each elapsed time

 FIG. 6B is a time chart for explaining the relationship between unit time and elapsed time in the wire thread breakage prevention method according to the flowchart of FIG.

 FIG. 6C is a time chart illustrating the relationship between unit time and elapsed time in the wire thread breakage prevention method according to the flowchart of FIG.

 Explanation of symbols

[0013] 1 wire

 4 Twisting device

 6 Motor

 10 Measuring means

 11 Control means

 Ad Measured change rate of Tonolek

 Ae Rate of change of the specified torque

 T1 unit time

 T2 elapsed time

 BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows a main part of a reinforcing bar binding machine according to an exemplary embodiment of the present invention. This rebar binding machine consists of a wire feeder 2 that feeds the wire 1 wound around the spool 7 forward, a guide arm 3 that winds the fed wire 1 in a loop, and a part of the wound wire 1 A torsion device 4 for gripping and tightening, and a cutting device 5 for separating the wire loop from the original wire 1 and Is provided. 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.

 [0015] In this reinforcing bar binding machine, the main switch 14 is inserted, the trigger lever 8 is pulled and the trigger switch 12 is turned on, so that the wire feeder 2 feeds the wire 1 from the spool 7, and the guide After the arm 3 is wound around the reinforcing bar a in a loop, the twisting device 4 is actuated, and a part of the wire loop la is gripped by the hook 9 and twisted and rotated to bind the reinforcing bar a, and the cutting device 5 Cut the wire loop la from the original wire 1 and divide it.

 [0016] 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 timing of the end of binding are determined from the torque measured by the measuring means, and the motor 6 is stopped for binding. Control means 11 for ending is provided!

 [0017] Fig. 2 shows a block diagram of a reinforcing bar binding machine. Reference numeral 10 is a measurement 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 voltage supplied from the battery pack. Shows a DC-DC converter that converts the voltage into a voltage for operating the control means.

 [0018] The measurement means 10 is connected in series to the motor 6 and measures the drive current of the motor 6. Therefore, the change in torque of the motor 6 can be monitored by measuring the drive current. This measuring means 10 is composed of a resistance element, and the driving current flowing through the circuit is obtained from the terminal voltage of this 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. The measurement result d measured by the measuring means 10 is input to the control means 11.

 [0019] The control means 11 is composed of a microprocessor, and monitors changes in the torque of the motor 6 and controls the voltage applied to the stator coil of the motor based on a control program residing in the built-in memory! The switching elements (for example, power transistors) 16a to 16d are controlled so as to control the drive signals e1 to e4 to control the rotational speed, operation and stop of the motor 6.

[0020] Based on the timer signal t from the timer circuit 17, the control means 11 determines the change in the current flowing through the motor 6 and the past (unit) measured drive time value every time the unit time T1 elapses. The torque change rate is monitored from the drive current value measured back to several times (time T1). [0021] 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. However, 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 this change rate is the predetermined change rate. When it becomes smaller, it is determined that the reinforcing bars are sufficiently bound, and the motor 6 is stopped by switching the drive signals el to e4 of the motor 6.

 [0022] As shown in the motor drive current characteristic curve of FIG. 3, the criterion for judging that the binding is sufficient is that the characteristic curve becomes gentle when the wire begins to twist, and the motor 6 If you continue to twist the wire by rotating the wire, the wire will eventually be twisted, and if the wire is twisted, the load on the motor 6 will disappear and the drive current will decrease rapidly, so the rate of change in the drive current will increase. What is necessary is just to set the rate of change just before becoming zero as a predetermined rate of change.

 [0023] It should be noted that even if the rebar binding is somewhat weak by the user, it is better not to cause the thread to break, and even if a twisted wire appears among the multiple wires, the rebar binding is stronger. Since there may be cases where it is judged good, it is not possible to determine the rate of change in general! /, Because there are cases where it is not shown! /, The setting dial can be used to change the size of the rate of change, Try to actually change the rate of change by turning the setting dial from the bundling situation.

 [0024] According to the wire thread breakage prevention method in the above-described reinforcing bar binding machine, a part of the wire loop la wound around the reinforcing bar crossing is gripped by the hook 9, and the motor 9 is rotated to rotate the hook 9. When tightening, monitor the timing when the torque (drive current) change rate of the motor 6 becomes smaller than the predetermined change rate, and stop the motor 6 at this point to fully twist the wire. In this state, the binding can be terminated, and the binding can be terminated before the wire to be threaded is cut by simply performing the torsional tightening.

[0025] Since the torque change rate does not always change smoothly depending on the thickness of the reinforcing bar and the number of wires, a plurality of the same change rates V may occur, and even if the predetermined change rate is reached. Since there is a case where the unity is surely performed! /, N! /, There is a separate timing for monitoring the rate of change. As shown in Fig. 3, this monitoring start time is the time T when it is determined that the torsion has progressed and the change rate of the torque has increased, and / or the torque Ma. The monitoring is started from the time when the condition is cleared.

 [0026] Because of this, when the winding starts, the curve is gentle and the torsion proceeds and the torque increases, so the change in the curve increases, and when the binding progresses, the curve becomes gentle again, so the same rate of change A occurs in the initial stage. Therefore, it is not possible to end the binding only by looking at the change rate A, and if the binding is terminated by looking at the change rate A after the torque reaches the predetermined value Ma or higher, the wire is tightened. There is no longer a situation where the binding is terminated in an incomplete state.

 Next, a method for preventing wire thread breakage of the above-described reinforcing bar binding machine will be described based on the flowchart in FIG. 4 and the time chart in FIG. 6B.

 [0028] By pulling the trigger button to rotate the motor, the torque is measured every unit time, and the elapsed time from the start of rotation is monitored (step ST1). It is determined whether the torque exceeds a predetermined value Ma or a predetermined time has passed (step ST2). If the set threshold value is exceeded, the process proceeds to step ST3 and monitoring of the torque change rate is started.

 [0029] The torque is measured every unit time T1 (for example, 10 ms), and the measured current torque M (n) and the torque M (n—X before x) (for example, 5 times the elapsed time T2 is 50 ms). ) To calculate the torque change rate Ad (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 the twisting is sufficient, and the motor is stopped to stop the twisting (step ST7).

 [0030] 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 incremented, and the flow returns to step ST3 to return to the next unit time T1. Measure the torque M (n) after elapse of time, calculate the torque change rate Ad again in step ST4, and step ST3 until the torque change rate Ad becomes the same force as the predetermined change rate Ae. Repeat ~ ST6.

 [0031] The above-described thread breakage prevention method shifts the time for measuring torque by unit time T1 (for example, 10ms) sequentially, and measures the torque measured every unit time T1 and X unit times T1 (for example, For example, the change rate of the torque is calculated by referring to the torque of five pieces before the elapsed time T2 is 50 ms).

That is, when calculating the rate of change of torque at the elapsed time T2 (for example, 50 ms), the elapsed time T2 is shifted to the elapsed time T2 while shifting the elapsed time T2 by unit time T1 (for example, 10 ms). The rate of change in torque is calculated. As shown in Fig. 6A, if the rate of change of torque is simply measured every elapsed time T2 (50ms), the wire may be broken before the next measurement. However, as shown in Fig. 6B, by monitoring the rate of change while shifting the elapsed time T2 little by little (by unit time T1), the predetermined rate of change can be recognized before the wire breakage occurs. Can do. Moreover, by setting the elapsed time to be larger than the unit time, the noise of torque change can be ignored, and the timing to capture the thread break in the time period until the next torque change rate is measured. You can avoid losing your power. The unit time T1 described above is not limited to 10 ms, but can be set arbitrarily, such as 2 ms or 3 ms. The elapsed time T2 can also be set to any value that is not limited to five times the unit time T1. Good.

 [0033] In the above-described twist-off prevention method, the rate of change in torque during the elapsed time is calculated while shifting by unit time, but the rate of change for each elapsed time and the rate of change within a short time within the elapsed time. A method for monitoring the two change rates and preventing twisting will be described based on the flowchart of FIG. 5 and the time chart of FIG. 6C.

 [0034] The trigger button is pulled to rotate the motor, and the torque is measured every unit time, and the elapsed time from the start of rotation is monitored (step ST11). It is determined whether a force for which the torque threshold exceeds a predetermined value Ma and a predetermined time have elapsed (step ST12). If the threshold and the predetermined time have elapsed, monitoring of the torque change rate is started (step ST13).

 [0035] The torque is measured every unit time T1 (for example, 10 ms), and the measured torque M (n) and the torque M (n—x) before the unit time force (for example, 5 units and the elapsed time is 50 ms). Calculate the torque change rate (first change rate) Adl when the first elapsed time T2 has elapsed from step 1 (step ST14). Calculate the torque change rate (second change rate) Ad2 when the second elapsed time T3 has elapsed from the previous Tonlek M (n−y) (step ST15). If the change rate Adl force S, the force smaller than the predetermined change rate Ae, and the second change rate Ad2 are negative, the motor is stopped and the torsion is stopped (step ST18).

[0036] If the calculated first change rate Adl is greater than the set change rate Ae or the second change rate Ad2 is not negative, it is determined that the torsion is still incomplete, and the counter is turned on in step ST17. Return to step ST13, measure the torque M (n) after the next unit time T1, and calculate the torque change rate again in steps ST14 and 15, so that the torque change rate is Repeat steps ST13 to ST17 until the rate of change is reached.

[0037] In the above-described twist-off prevention method, the rate of change in torque is greater than the first rate of change Adl at the first elapsed time T2 and the first elapsed time T2 set at the end of the first elapsed time. The second change rate in the short second elapsed time T3 is determined based on the two change rates with Ad2, and when the first change rate Adl becomes smaller than the predetermined change rate Ae, or When the second rate of change Ad2 becomes negative, the motor is stopped and the torsion is stopped.

 [0038] By this, it can be seen that the twisting of the wire has reached a peak, and the motor can be stopped before all the wires are threaded, so that the binding can be performed more reliably. Can be realized. In the above-described reinforcing bar binding machine, the rate of change in torque 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 the performance of the battery or the motor.

 [0039] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. It is.

 [0040] This application is based on a Japanese patent application filed on July 24, 2006 (Japanese Patent Application No. 2006-200396), the contents of which are incorporated herein by reference.

 Industrial applicability

[0041] The present invention is applicable to a reinforcing bar binding machine.

Claims

The scope of the claims  [1] Measure the drive torque of the motor that rotates the hook that holds the wire that binds the reinforcing bars with the drive current,  When the change rate of the driving torque becomes smaller than the predetermined change rate, the torsional tightening by the motor is finished,  Monitoring the rate of change of the drive torque is measured by either or both of the force that starts after a predetermined time has elapsed from the start of twisting, the drive torque that starts after the drive torque reaches a predetermined value, or both.  A method for preventing wire breakage in a reinforcing bar binding machine.  [2] The drive torque of the motor is measured every unit time,  Monitoring the rate of change of drive torque based on the torque measured per unit time and the torque measured a predetermined number of times before;  The method for preventing thread breakage of a wire according to claim 1. [3] The driving torque of the motor is measured every unit time,  Monitoring the first rate of change of the driving torque based on the torque measured per unit time and the torque measured before the first predetermined number of times;  Monitoring the second rate of change of the drive torque based on the torque measured before the second predetermined number of times less than the first predetermined number of times,  When the first rate of change becomes smaller than the predetermined rate of change or when the second rate of change becomes negative, the torsional tightening by the motor is terminated.  The method for preventing thread breakage of a wire according to claim 1.