JPS6247156B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a bolt tightening alarm device.

Bolts are used in all types of equipment, equipment, and appliances, including industrial machinery and transportation machinery, and it is an extremely important issue to appropriately select the tightening value for bolts. Inappropriate tightening of bolts can cause accidents, so in recent years, the management of bolt tightening has become particularly important, and alarm devices have been proposed that issue an alarm when bolt tightening is not at an appropriate value. For example, in Japanese Patent Application No. 50-67853, a bolt tightening control circuit is provided, and an alarm device is configured to receive a shear failure signal and a trigger switch signal from this control circuit to notify abnormality in bolt tightening. Disclosed.

However, as exemplified by the above-mentioned alarm device, conventional alarm devices determine abnormal tightening by receiving the shear breakage signal and trigger switch signal from the control circuit, so the circuit configuration of the device itself is complicated. Moreover, since there was a difference between the actual tightening torque and the timing at which the alarm device activated, the timing at which the alarm was issued was inaccurate.

The present invention solves these drawbacks of conventional alarm devices, and there is no signal exchange between the bolt tightening device and the alarm device, such as a break signal or a trigger switch signal, and any tightening abnormalities are not recorded on the record paper. It can be determined and is configured to issue an alarm in the event of this tightening abnormality.

The basic configuration of the alarm device of the present invention includes an upper limit torque setter and a lower limit torque setter for respectively setting the upper limit torque level, lower limit torque level, and boundary torque level determined in the tightening torque waveform of the bottle tightening machine. and a boundary torque setting device, a timer setting device for setting a period in which the tightening torque exceeds the boundary torque level in the tightening torque waveform, a torque detector for detecting the tightening torque of the bolt tightening machine, and the torque detector. an upper limit torque comparator, a lower limit torque comparator, and a boundary torque comparator that compare the output of the upper limit torque level, the lower limit torque level, and the boundary torque level, respectively; and a tightening torque is determined in response to the output of the boundary torque comparator. and a timer for measuring the time during which the torque exceeds the boundary torque level, and when the upper limit torque comparator has an output,
or an alarm that issues an alarm when there is no output to the lower limit torque comparator within the time measured by the timer or when the time measured by the timer is not within the time set by the timer setting device. A recording section can be installed as needed.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

There are two methods for recording bolt tightening torque: a motor current waveform recording method and a method for recording signals converted by a torque converter such as a strain gauge, and the following explanation will focus on the latter.

Figure 1 shows the bolt tightening control circuit, in which the torque setting device 1 is set to a predetermined level, and the starting switch 2 is turned on.
When turned on, current flows from the power source 3 to the thyristor circuit 4, field coil 5, armature 6, and current detector 7, causing the motor to rotate. This rotates the socket 10', which is detachably attached to the tip of the output shaft of the bolt tightening machine 10, and tightens the bolt (see FIG. 2). As a result, the current flowing through the armature 6 increases, approaches the set level of the torque setting device 1, and when it reaches a value corresponding to the set torque level, the phase control circuit 8 sends a shear break signal to the shear break signal generator 9. output, thereby thyristor circuit 4
turns off, the motor stops, and tightening is completed. The change in tightening torque during this period is caused by the reaction force receiver 11
The torque is detected by a torque detector 12 attached to and recorded on a recorder 13.

FIG. 3 shows the change in tightening torque with respect to time from the start to the completion of bolt tightening, with the horizontal axis representing the tightening time and the vertical axis representing the tightening torque. In the figure, time t _E is the time when bolt tightening is completed, and torque value T _E corresponds to the torque value when bolt tightening is completed.

By the way, as shown in Fig. 3, the torque value T _E at the time of completion of tightening is within the range of the upper limit setting value UCL and the lower limit setting value LCL, and the time t _E required to complete tightening is within the upper limit time t _U and the lower limit time t _L. , i.e. (T _E .t
If _E ) is within the diagonal line, there is no problem, but if it is not within this range, there is some kind of abnormality.

Now, FIG. 4 is a block diagram of a control circuit of the alarm device in which the alarm device according to the present invention is applied to an electric bolt tightening machine. In the figure, B1 is an alarm circuit section, and B2 is a recording section. First, in the alarm circuit section B1, the upper limit torque setter 15 generates a signal indicating the upper limit value UCL of allowable torque at the time of completion of bolt tightening, and the lower limit torque setter 16 indicates the lower limit value LCL of allowable torque at the time of completion of bolt tightening. The boundary torque setting device 17 generates a signal, which is the start level of the timer, and detects that actual tightening has been performed and the bolt tightening machine is in a loaded operation state, and is not in a no-load operation or other state. This is to distinguish it from disturbances and emits a signal indicating the boundary value TSL. This boundary value, as explained below
No alarm will be issued even if torque below TSL is detected.

The upper limit torque comparator 18 issues a logic "1" signal when the torque value detected by the torque detector 12 is greater than the torque upper limit value UCL, and issues a logic "0" signal when it is less than the upper limit value UCL. The lower limit torque comparator 19 issues a logic "1" signal when the detected torque value is greater than or equal to the lower limit value LCL, and issues a logic "0" signal when it is smaller than the lower limit value LCL. The boundary torque comparator 20 generates a logical "1" signal when the detected torque value is greater than or equal to the boundary value TSL, and generates a logical "0" signal when it is smaller than the boundary value TSL. The output of the upper limit torque comparator 18 is input to an OR circuit 22. The output of the lower limit torque comparator 19 is output from the flip-flop 23.
The output of the boundary torque comparator 20 is input to the NAND circuit 24 via the flip-flop 25.
The signal is input to the AND circuit 26 , and is also input to the AND circuit 26 via the inverter circuit 27 . Also, the output of the boundary torque comparator 20 is the output of the flip-flop 2.
8 and is input to the timer 29 for measuring the lower limit time and the timer 30 for measuring the upper limit time. Furthermore, the output of the boundary torque comparator 20 is transferred to the inverter circuit 31.
A part of the output of the boundary torque comparator 20 is input to the AND circuit 32 through the AND circuit 32.
3. The lower limit time measurement timer 29 receives a signal from the lower limit time measurement timer time setter 34 and inputs its output to the AND circuit 32 . The upper limit time measurement timer 30 receives a signal from the upper limit time measurement timer time setter 35 and sends its output to the AND circuit 3 via an inverter circuit 36.
Enter to 3. The outputs of these AND circuits 32 and 33 are input to an OR circuit 22.

The output of the AND circuit 26 is input to the NAND circuit 24 and also to the timer 37. The output of the timer 37 is output from each flip-flop 23, 2.
5 and 28 are respectively input to a reset circuit 38 which resets them after the set time of a timer 37.
The output of the AND circuit 26 is input to the AND circuit 39, and the output of the NAND circuit 24 is also input to the AND circuit 39.
The output of the AND circuit 39 is input to the OR circuit 22. The output of the OF circuit 22 is input to an alarm device 40 to issue an alarm.

The output of the torque detector 12 is strain up 4
1 and then input to comparators 18, 19, and 20.

In the recording section B2, an upper limit torque setter 15,
Lower limit torque setter 16 and boundary torque setter 1
The value 7 is recorded on the recorder 13 only when the changeover switch 42 is changed and the changeover button 43 is pressed.Other than that, the output of the torque detector 12 is recorded on the recorder 13 via the strain amplifier 41. Ru.

Next, the operation of the control circuit shown in FIG. 4 will be explained with reference to FIG. In the figure, an arrow X indicates the point in time when abnormality in bolt tightening is determined.

The upper limit value of allowable torque (upper cut level UCL) is set by the upper limit torque setting device 15,
The lower limit torque setting device 16 sets the lower limit of allowable torque (low cut level LCL), and the boundary torque setting device 17 sets the boundary torque value (TSL) that determines whether the bolt tightening machine is under no load or under load. be done.

When the torque value of the bolt tightening machine is input from the torque detector 12 to the boundary torque comparator 20 via the strain amplifier 41, it is compared with a boundary torque value (TSL). When the torque value exceeds the TSL, the output of the boundary torque comparator 20 is transferred to the flip-flop 28.
The lower limit time measurement timer 29 and the upper limit time measurement timer 30 keep the logic "1" only during the time set by the lower limit time measurement timer time setter 34 and the upper limit time measurement timer time setter 35, respectively. Output. The output of the timer 29 is input to an AND circuit 32. If the bolts are properly tightened, the relationships will be as shown in FIGS. 5A and 5B. When the logic “1” level output from the boundary torque comparator 20 is shorter than the set time of the lower limit time measurement timer time setter 34
The AND circuit 32 supplies a logic signal "1" to the OR circuit 22, which activates the alarm 40 and issues an alarm. This is the case when a bolt that has been tightened once is tightened again (double tightening) (see Figure 5E). Conversely, when the logic "1" level output from the comparator 20 is longer than the set time of the timer time setter 35 for measuring the upper limit time, it means that auto-cutting is not performed, and in this case, the logic is output from the AND circuit 33. “1”
A signal is applied to the OR circuit 22 which also outputs the alarm 40.
is activated and issues an alarm. This indicates that the tightening time has taken too long and indicates a tightening machine rotation or bolt abnormality (see Figure 5F).

When the torque value of the bolt tightening machine supplied from the torque detector 12 via the strain amplifier 41 exceeds the upper cut level UCL set by the upper limit torque setting device 15, the upper limit torque comparator 18
The output of
reference).

The torque value of the bolt tightening machine supplied from the torque detector 12 via the strain amplifier 41 reaches the lower cut level LCL set by the lower limit torque setting device 16 within the logic “1” period of the boundary torque comparator 20. If that doesn't work, use OR circuit 2
2 is given an alarm signal, which in turn activates the alarm device 40 to issue an alarm. This indicates that the bolt is insufficiently tightened (see Figure 5D).

As described above, in the present invention, an abnormality in bolt tightening can be determined and an alarm is issued only from the torque value waveform of the bolt tightening machine, so the circuit configuration is simpler compared to conventional alarm devices. Since there is no lag between the tightening torque and the timing at which the alarm device operates, the timing at which the alarm is issued is accurate. It is very advantageous both in terms of production and operation.

[Brief explanation of the drawing]

Figure 1 of the accompanying drawings is a block diagram of a conventionally known bolt tightening control circuit, Figure 2 is a tightening torque recording device for a bolt tightening machine, and Figure 3 shows changes in the tightening torque of the bolt tightening machine over time. Explanatory diagram,
FIG. 4 is a control circuit block diagram of the bolt tightening alarm device according to the present invention, and FIG. 5 is an explanatory diagram showing torque curves in various modes of abnormal bolt tightening in relation to respective set values. 1...Torque setting device, 2...Start switch, 3
... Power supply, 4 ... Thyristor circuit, 5 ... Field coil, 6 ... Armature, 7 ... Current detector, 8 ...
Phase control circuit, 9... Shrinkage signal generator, 10...
... Bolt tightening machine, 11 ... Reaction force receiver, 12 ... Torque detector, 13 ... Recorder, 15 ... Upper limit torque setting device, 16 ... Lower limit torque setting device, 17 ...
... Boundary torque setter, 18 ... Upper limit torque comparator, 19 ... Lower limit torque comparator, 20 ... Boundary torque comparator, 22 ... OR circuit, 23, 25, 2
8...Flip-flop, 24...NAND circuit,
26, 32, 33, 39...AND circuit, 27,
31, 36, 41... Inverter circuit, 29...
Timer for lower limit time measurement, 30...Timer for upper limit time measurement.

Claims (1)

[Scope of Claims] 1. An upper limit torque setting device and a lower limit torque setting device that respectively set the upper limit torque level and lower limit torque level when tightening bolts by a bolt tightening machine, and detecting the actual tightening torque of the bolt tightening machine. a torque detector that sets a boundary torque level for detecting the load operating state of a bolt tightening machine; a boundary torque setter that sets a boundary torque level for detecting the load operating state of a bolt tightening machine; When the outputs of the upper limit torque comparator, lower limit torque comparator, and boundary torque comparator that are compared, and the torque detector exceed the boundary torque level,
An upper limit time measurement timer and a lower limit time measurement timer operate using the signal output from the boundary torque comparator, and an alarm is generated by the signal output from the upper limit torque comparator when the output of the torque detector exceeds the upper limit torque level. When the period of the signal output from the boundary torque comparator is shorter than the lower limit time set on the lower limit time measurement timer and longer than the upper limit time set on the upper limit time measurement timer. If the output of the torque detector has not reached the lower limit torque level within the period of the signal output from the boundary torque comparator, the alarm is activated by the signal output from the lower limit torque comparator. A bolt tightening alarm device consisting of a logic circuit that activates an alarm. 2. An upper limit torque setter and a lower limit torque setter that respectively set an upper limit torque level and a lower limit torque level when tightening bolts with a bolt tightening machine, and a torque detector that detects the actual tightening torque of the bolt tightening machine; A boundary torque setting device that sets a boundary torque level for detecting the load operating state of a bolt tightening machine, and an upper limit torque comparison that compares the output of a torque detector with an upper limit torque level, a lower limit torque level, and a boundary torque level, respectively. When the outputs of the detector, lower limit torque comparator, boundary torque comparator, and torque detector exceed the boundary torque level,
An upper limit time measurement timer and a lower limit time measurement timer are activated by the signal output from the boundary torque comparator, and an alarm is generated by the signal output from the upper limit torque comparator when the output of the torque detector exceeds the upper limit torque level. When the period of the signal output from the boundary torque comparator is shorter than the lower limit time set on the lower limit time measurement timer and longer than the upper limit time set on the upper limit time measurement timer. If the output of the torque detector has not reached the lower limit torque level within the period of the signal output from the boundary torque comparator, the alarm is activated by the signal output from the lower limit torque comparator. A logic circuit that activates the alarm and a recording section that allows the recorder to record the output of the torque detector, or the output of the upper limit torque setter, lower limit torque setter, and boundary torque setter while the bolt tightening machine is in operation. A bolt tightening device consisting of.