JPS62259783A - Bolt screwing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a bolt tightening machine that controls a motor by feeding back tightening torque, tightening angle, etc. to a motor control device.

(Background of the Invention) There has conventionally been a bolt tightening machine that detects tightening torque and tightening angle and controls a motor so that these detection results are constant. In this case, conventional devices are equipped with one torque detector, one angle detector, and one rain detector, so if one detector malfunctions, normal operation is impossible. It was something that would become.

In addition to detecting the tightening torque and tightening angle, if an electric motor is used, a motor current limiting circuit is installed, and a timer is installed to monitor the tightening time. There is also a conventional method that detects an abnormality in the attached time. However, in this case, if a tightening abnormality occurs, it is difficult to detect it, and it is also very difficult to know where the abnormality is.

In this way, with conventional equipment, normal operation is no longer possible if an abnormality occurs in one part such as the detector, and the MTEF
There was a problem that the mean time between failures (mean time between failures) became extremely short. Furthermore, since it is difficult to discover abnormalities, the time required for repair, ie, MTTR (Mean Time to Repair), becomes longer, and there is also the problem that the operating rate of the port tightening machine decreases.

(Object of the invention) The present invention has been made in view of the above circumstances, and includes:
To provide a port tightening machine that does not cause the entire operation to become disabled or abnormal even if a failure occurs in a few places, and can increase the operating rate by increasing the MTBF and shortening the MTTR. The purpose is to

(Structure of the Invention) According to the present invention, the object is to feed back a signal indicating the tightening state of at least one of the tightening torque and the tightening angle to the motor control device to control the motor. , a plurality of tightening state detectors for detecting the tightening state, a deviation detector for detecting a deviation of the output signal of each of these tightening state detectors, and a deviation detector for detecting whether or not this deviation is within a tolerance value. a deviation discriminator that discriminates, a plurality of first discriminators that discriminate whether the output signal of each of the tightening state detectors is out of a set range, and an abnormality based on the output of the deviation discriminator and each of the first discriminators. and a selection circuit that sends one of the signals indicating the tightening state to the control device,
The discriminator is achieved by a port tightening machine characterized in that it controls the selection circuit so as to send the output of the tightening state detector in which there is no abnormality to the control device.

(Example) FIG. 1 is a block diagram of an embodiment of the present invention.

In this figure, reference numeral 10 is an AC power supply, 12 is a control device, 14 is an electric motor, 16 is a transmission device such as a reducer, 1
8 is a socket. The socket 18 engages a nut screwed into the pole 20. In this embodiment, the tightening torque is fed back to the motor 14 as a signal indicating the tightening state. In other words, the transmission device 16 is provided with two torque sensors 22a and 22b such as strain gauges as tightening state detectors.
Torque signal Ta or Tb, which is the output of
4 and fed back to the control device 12. Control device 1
2 controls the motor 14 based on the selected torque signal Ta or Tb. For example, when using the torque method, tightening is stopped when the torque signal Ta or Tb reaches a constant value.

26 is the deviation between the torque signals Ta and ``rb ('ra-Tb)
A deviation detector 28 calculates the absolute value lTa Tb
Absolute value circuit for calculating l, 30 is this absolute value IT, -Tb
A deviation discriminator 32 which determines whether l is within the allowable value Δτ is a setter for this allowable value ΔT. Therefore, this deviation discriminator 30 outputs a deviation signal a of logic O1 if the deviation (T a T b ) is within the allowable value ΔT, and outputs a deviation signal a of logic 1 if it is not within the tolerance value ΔT.

34a and 34b are first discriminators made of window comparators, and each first discriminator 34a.

34b are the torque signals "ra, 'rb are V, , v, respectively.
It outputs a torque level signal S, c which becomes a logic 0 if it is within the range of the upper and lower limits indicated by L, and becomes a logic 1 if it is outside this range.

A second discriminator 36 discriminates whether or not there is an abnormality based on the deviation signal a and the torque level signals S and C. For example, if there is an abnormality in one of the torque sensors 22a and 22b,
The switching circuit 24 is controlled so that the torque signal Ta or TIl from one of the normal torque sensors 22a or 22b is input to the control device 12. This switching circuit 24 has analog switches 24a and 24b that are selectively closed by the outputs e and f of this second discriminator 36. The second discrimination circuit 36 displays the presence or absence of an abnormality and the type of abnormality on a display device 38.
to be displayed.

Next, the operation of this embodiment will be explained. The second discriminator 36 uses the external condition d1. d2, etc. are input, and the presence or absence of an abnormality and the location of the abnormality are determined from these and the states of the respective signals a, b, and c. For example, as condition d1, a signal that is logic 1 while the motor 14 is rotating and logic O when it is stopped is input, and as condition d2, a signal that is required for normal tightening after starting the motor 14 (starting the tightening operation) is input. A signal is input which becomes logic 01 only during time t and becomes logic 1 after time t. Further, when everything is normal, this second discriminator 36 closes the analog switch 24a and transmits the torque signal T to the control device 12.
Contains a priority circuit that inputs to

For example, before starting the motor 14, the condition d1 is logical 0;
At this time, if either of the torque signals S and C is logic 1, the torque sensor 22a or 2 of the system that outputs logic 1
If 2b is abnormal and both signals S and C are logical 1, both torque sensors 22a and 22b are abnormal or the transmission device 16 or socket IB is mechanically locked. The second discriminator 36 displays this abnormal location on the display device 38 and sends a signal to input the torque signal Ta or Tb of the logic O (normal) system to the control device 12 if one of the signals S and C is logic 1. Turn on either e or f.

If the motor 14 is started (condition d1 is 1), within the predetermined time t (condition d2 is O), and the signal a is 0, the deviation is within the allowable range Δτ, so tightening is normal. If c is in progress and signaled within a predetermined time, it is normal. However, if the signal c never reaches l within a predetermined period of time, it is determined that the target torque has not been reached or the bolts are rotating together, and that an abnormality has occurred. signal,
If only one of c becomes 1, it is determined that there is an abnormality in the circuit of one system.

If the signal a becomes 1 within a predetermined time (the deviation is large) and the signals S and C both become 1, the torque sensor 22
There is an abnormality in a, 22b or the torque signal transmission path.

Even if the signal a is 1 after the predetermined time t has elapsed, proper tightening is possible if one of the torque signal systems is normal, but if the system is abnormal, a message to that effect is displayed.

Although the electric motor 14 is used in the embodiment, the present invention also includes a motor using an air motor or a hydraulic motor.

Further, in this embodiment, the torque sensor 22a.

Although the tightening state detector 22b is used, the present invention may also include two or more torque sensors and two or more first discriminators.

In addition, when tightening is performed using the rotation angle method, two or more tightening angle sensors may be used as tightening state detectors, or both torque and tightening angle can be measured using two or more torque sensors and two or more tightening angle sensors. It may be detected and tightened using the torque/rotation angle method, for example.

(Effects of the Invention) As described above, the present invention has multiple systems for detecting tightening torque and tightening angle, so if a failure occurs, tighten using the system that does not have the failure! The MTBF of the entire device becomes longer. For example, if the failure rate of one system is P (0<P<1), the overall failure rate, that is, the probability that tightening becomes impossible, is P2, which significantly reduces the failure rate.

Also, if you monitor the temporal changes in signals a, b, and c,
Failure locations can be predicted to some extent. Therefore, the average repair time MTTR becomes shorter.

This increases the operating rate of the device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention. 12... Control device, 14... Motor, 22a, 22b... Torque sensor as a tightening state detector, 24... Switching circuit, 26... Deviation detector, 30... Deviation determination device, 3.4 a, 34 b--・first discriminator, 36...
・Second discriminator.

Claims (1)

[Claims] In a bolt tightening machine that controls a motor by feeding back a signal indicating a tightening condition of at least one of tightening torque and tightening angle to a motor control device, a plurality of tightening conditions are detected. a detector, a deviation detector that detects a deviation in the output signal of each of these tightening state detectors, a deviation discriminator that determines whether or not this deviation is within a tolerance value, and each of the above-mentioned tightening state detectors. a plurality of first discriminators that determine whether the output signal of the first discriminator deviates from a set range; a second discriminator that determines whether there is an abnormality based on the output of the deviation discriminator and each first discriminator;
a selection circuit that sends one of the signals indicative of the tightening state to the control device; A bolt tightening machine characterized by control.