JPH0718501Y2 - Forgetting to prevent screw tightening - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a device for preventing forgetting to tighten a screw when a screw is tightened at a plurality of positions of a single work by using a screw tightener.

<Prior art> This type of screw tightening prevention device conventionally measures the time from the first screw tightening to the last screw tightening, compares this measured time with a preset reference time, and measures the measured time. If the time exceeds the reference time, it is judged that the screwing has been forgotten and a warning such as a buzzer or lamp is issued.

<Problems to be solved by the invention> However, in the structure of such a conventional device for preventing screw tightening, the screw tightening is judged based on the time from the first screw tightening to the last screw tightening. Since the Kiju time is set according to the time when all screw tightening is completed, it takes a long time to know the judgment result.

For example, when tightening the screws at 5 points on a single workpiece, if you tighten the screws only at 1 point and forget to tighten the other 4 points, you must wait for a preset long reference time. The judgment result is not notified.

Further, even if some trouble occurs during the screw tightening and the measurement time becomes long, there is a possibility that the screw may be forgotten to be erroneously determined.

In view of the above-mentioned conventional problems, the present invention aims to shorten the determination time and prevent erroneous determination by improving the method of setting the reference time for determining whether the screw is forgotten to be tightened. An object is to provide a device for preventing forgetting to tighten.

<Means for Solving the Problems> For this reason, the device for forgetting to tighten screws according to the present invention, as shown in FIG. 1, uses a screw tightener to tighten screws at a plurality of positions on a single work. A device for preventing a user from forgetting to tighten the screw, in which the screw tightening interval measuring means individually measures the screw tightening interval of the time between the torque-up signals output from the screw tightener, and the previous reference time and the current measurement. The sum of the set screw tightening interval is divided by 2 to set the reference time for the next time, and the reference time is set when the start signal output from the screw tightener is input during screw tightening. Extension reference time setting means for setting a reference time extended by adding a predetermined time, comparison means for comparing the actual screw tightening interval with the reference time or the extension reference time, and a comparison result by the comparison means. Based And a determination means for determining whether the screw is forgotten to be tightened.

<Operation> In the above configuration, the torque-up signal output from the screw tightener is input to the measuring means, and the time from the torque-up signal of the first screw to the torque-up signal of the second screw is measured by the measuring means. The time from the torque-up signal of the second screw to the torque-up signal of the third screw is measured, and the measured time is compared with the preset reference time each time.

Then, the reference time is set as the next reference time by dividing the sum of the previous reference time and the currently measured screw tightening interval by 2.

Then, when the start signal is input from the torque driver during the screw tightening, that is, between the torque-up signal and the next torque-up signal, the reference time is extended by adding a predetermined time to the reference time.

This can be judged to be a trouble occurrence when the torque up signal is not output despite starting the torque driver,
At this time, since the torque driver is restarted again,
It becomes clear that trouble has occurred.

At this time, the screw tightening interval inevitably becomes long, so the reference time is extended as described above.

According to this structure, the screw tightening interval is individually measured and compared with the reference time set each time to determine whether the screw is forgotten to be tightened. If you tighten the screws only in one place and forget to tighten the screws in the other four places when you tighten the screws, the judgment result will be notified without waiting a long time.
The determination time can be shortened.

In addition, the reference time is set so as to be biased each time by dividing the sum of the previous reference time and the screw tightening interval measured this time by 2, so that the reference time is set to the individual difference and the fatigue. It can be set to a time that takes into account the variation in work time due to.

In addition, if some trouble occurs during screw tightening, the reference time is added to the reference time to extend the reference time. It will not be judged that you have forgotten to tighten,
Misjudgment can be prevented.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows the hardware configuration.

In the figure, a microcomputer is also incorporated in the control unit 1 as a control unit of the device for preventing the screw tightening forgetting. A torque driver 2 as a screw tightener outputs a start signal and a torque-up signal, and these signals are input to a microcomputer. The control panel section of the device is equipped with a tightening number setting switch 3, a defective tightening number display switch 4, an OK buzzer 5, an NG buzzer 6, and two LED indicators 7 and 8. A signal from the tightening number setting switch 3 is input to the microcomputer to set the screw tightening number n. A signal from the display switch 4 is input to the microcomputer, and the microcomputer inputs a command to stop the buzzer 6 and a defective tightening number display on the one LED display 7 by this signal input. Both buzzers 5,
The output signal from the microcomputer is input to 6, and the NG buzzer 6 functions as a warning means for outputting the judgment result of forgetting to tighten the screws. The OK buzzer 5 does not forget to tighten all the screws in the work. It functions as a notification means when it is hit. One of the LED indicators 7 receives the output signal from the microcomputer and displays the number of tightened screws and the number of defective tightened screws. Further, the other LED indicator 8 receives the output signal from the microcomputer and displays the number of OK works without forgetting to tighten the screws.

Here, the microcomputer has a screw tightening interval measuring means for individually measuring a time between torque up signals output from the torque driver 2 as a screw tightening interval, and a previous reference time and a currently measured screw tightening time. Reference time setting means for dividing the sum of the intervals by 2 and setting it as the next reference time, and a predetermined time for the reference time when a start signal output from the screw tightener is input during screw tightening. Extension reference time setting means for adding and setting the extended reference time, comparing means for comparing the actual screw tightening interval with the reference time or the extension reference time, and for the screw based on the comparison result by the comparing means. It also serves as a determination means for determining whether the user forgets to tighten.

Next, the function of such a microcomputer will be described based on the flowchart of FIG. 3, the block diagram of FIG. 4, and the time chart of FIG.

That is, in the flowchart of FIG. 3, in step (hereinafter, referred to as S in the same way as the drawing) 1, it is determined whether or not the display switch is turned on. If not, the process proceeds to S2 and is measured by the timer. The time between the torque-up signals of the work output from the torque driver 2, that is, the screw tightening interval T and a reference time preset as described later.
Comparing the T _n-1 + a or b, if T _n-1 + a or b <T, because there was Nagy forgetting to fasten a MG, the process proceeds to S3, and 1 up NG counter, Proceed to S4, NG buzzer 6
Turn on. If T _n-1 + a or b <T in S2, it is OK because you have not forgotten to tighten the screws, so proceed to S5 and increase the number of screw tightening of LED display 7 by 1 to S6. Proceed to determine whether the total number of screw tightening has reached n, and if it reaches n, the screw tightening of this work is complete. Therefore, proceed to S7, and count the number of works for which screw tightening has been completed. Increments the OK counter that counts, goes to S8, and sets the OK buzzer 5
Turn on. If the total number of screw tightening does not reach n in S6, screw tightening of this work is not completed.
The process proceeds to S1 and the same determination and execution as described above are performed in the subsequent steps. After S4 and S8, the process returns to S1 and the screw tightening forgetting judgment for the next work is performed.

Here, after the NG buzzer 6 is turned on, the screw is forgotten to be tightened, so the display switch 4 in FIG.
Turn on and stop the operation of the buzzer 6. LED indicator 7 by combination of tightening number set switch 3 and switch 4
You can also display the number of defective fasteners.

Next, the functions of the reference time setting means, the extended reference time setting means, the comparing means, and the judging means will be described with reference to FIGS. 4 and 5.

For example, when the total number of screws is 5, the torque-up signal output from the torque driver 2 is input to the timer, and the timer changes the torque-up signal from the first screw to the torque-up signal of the second screw. The time from the torque-up signal of the second screw to the torque-up signal of the third screw is measured, and each time the measurement time T is set in advance as a reference time T ₁ + b, T ₂ +
b, ...

Here, b added to the above T ₁ , T ₂ , ... Is a short time for allowing the reference time to have some width, and is set to, for example, 3 seconds.

Then, T _1, T ₂ · · · in the reference time, the determination result for each of the OK, as shown in the following equation, is the last reference time T _1, T ₂ ··· and the current measurement The sum of the screw tightening interval T is divided by 2 and set as the next reference time.

Then, as shown in FIG. 5, for example, when a start signal is input from the torque driver 2 during the screw tightening, that is, between the torque-up signal and the next torque-up signal, the reference time T ₃ is a predetermined time a. Is added to extend the reference time as T ₃ + a. The above-mentioned a is set to, for example, 10 seconds.

This is, despite starting the torque driver 2,
When the torque-up signal is not output, it can be determined that a trouble has occurred, and at this time, the torque driver 2 is restarted again, so that the trouble occurs. And at this time,
Since the screw tightening interval inevitably becomes long, the reference time as described above is extended.

Therefore, even if a trouble occurs and the measurement time T becomes long, it is not determined that the screwing has been forgotten.

In the example shown in FIG. 5, it is not forgotten to tighten the first to fourth screws, so the measurement time T is the reference time T ₁ + b,
It falls within T ₂ + b and T ₃ + a, but the measurement time T corresponding to the 5th screw does not fall within the reference time T ₄ + b used for determining the 5th screw, and the fifth screw is left unfastened. You can judge.

According to this structure, the screw tightening interval is individually measured and compared with the reference time set each time to determine whether the screw is forgotten to be tightened. If you tighten the screws only in one place and forget to tighten the screws in the other four places when you tighten the screws, the judgment result will be notified without waiting a long time.
The determination time can be shortened.

Also, the reference time is changed and set each time by dividing the sum of the previous reference time and the screw tightening interval measured this time by 2, so that the reference time is set to the individual difference and fatigue. It can be set to a time that takes into account the variation in work time due to.

If some trouble occurs during screw tightening, the reference time is added to the reference time to extend the reference time. It is possible to prevent erroneous determination without making a forgetting decision.

In addition, in the conventional device, the buzzer simply gives a warning when forgetting to tighten the screw, so it is not possible to grasp the number of screws left to be tightened or the number of defective works in each work, and feedback to improve the screw tightening process. However, in the present embodiment, the number of defective fastenings, the number of fastenings, and the number of good works are displayed, so that there is an advantage that feedback to the improvement of the screw fastening process can be performed. .

<Effect of Device> As described above, according to the present invention, by improving the method of setting the reference time for determining whether the user forgets to tighten the screw,
This is a great practical effect that can shorten the determination time and prevent erroneous determination.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a functional block diagram showing the configuration of a screw forgetting prevention device according to the present invention, FIG. 2 is a system diagram showing an embodiment of the same device, and FIG. 3 is control content. 4 is a similar block diagram, and FIG. 5 is a similar time chart. 1 ... Control unit, 2 ... Torque driver, 3
… Tightening number set switch, 4… Display switch, 5… OK buzzer, 6… NG buzzer, 7, 8… LED indicator

Claims (1)

[Scope of utility model registration request] 1. A device for preventing forgetting to tighten a screw when screwing a plurality of screws of a single work by using the screw tightener, the time between torque-up signals output from the screw tightener. And a reference time setting means for dividing the sum of the last reference time and the currently measured screw tightening interval by 2 and setting it as the next reference time. And an extension reference time setting means for setting an extended reference time by adding a predetermined time to the reference time when a start signal output from the screw tightener is input during screw tightening, and an actual screw tightening A screw tightening forgetting prevention device configured to include a comparing means for comparing an interval with the reference time or the extension reference time, and a judging means for judging whether the screw is forgotten to be tightened based on the comparison result by the comparing means.