JPH0225772Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a device for detecting longitudinal tearing of a belt caused by driving a belt conveyor while a foreign object is stuck in the belt.

Conventional technology When transporting earth, sand, ore, etc. using a belt conveyor, conventionally, the chute section at the start end of the belt conveyor or at the intersection of belt conveyors is generally
If objects to be conveyed, such as earth and sand, are falling, and heavy objects with sharp or sharp edges are mixed in, this may pierce the conveyor belt. In this case, if the belt conveyor continues to operate, the stuck heavy object will move with the belt to some extent, but the heavy object will hit the rollers that support the belt and prevent its movement, resulting in vertical tears in the belt. It will happen.

Conventionally, as a method of detecting the occurrence of such a situation, a method has been proposed, for example, of embedding a suitable sensor in the conveyor belt.
According to the No. 1 issue, a sensor consisting of a push contact formation switch is connected to a delay timer, and when the sensor operates for a certain period of time, it is determined that a vertical tear accident has occurred, and a device is installed that prevents malfunctions caused by temporary shocks, etc. Proposed.

Problems that the invention aims to solve: However, although it may be possible to reliably detect vertical tears with a belt embedded with the sensor described above, the belt itself is expensive, and even if there is a slight vertical tear, it will be difficult to detect. Because the sensor was embedded, there was a high risk that it would be difficult to repair it.

Furthermore, the device described in the above-mentioned Japanese Utility Model Publication No. 51-54225 may be able to prevent malfunctions caused by temporary impacts, but the forces acting on the belt at the chute section are diverse, and the device described in the above-mentioned publication is In a sensor such as a switch that can be pressed at any location, malfunctions cannot necessarily be prevented even if a delay timer is installed.

Therefore, in order to accurately detect the situation at the chute, the inventors of the present invention conducted extensive research into adopting a mechanism that includes a wire and a switch that operates by the tensile force acting on the wire, and found the following. It turned out that there was a problem. In other words, in order to perform reliable detection, if the wire is brought as close as possible to the underside of the belt, the tensile force on the wire will temporarily increase due to the impact force applied to the belt when a heavy object falls. , the switch may malfunction. On the other hand, if the wire is moved away from the underside of the belt to avoid malfunctions, even if a foreign object sticks into the belt, the foreign object will not reach the wire, resulting in a situation where vertical tearing of the belt cannot be detected. Furthermore, in a configuration in which the wire is brought close to the underside of the belt and a delay timer is used to prevent malfunctions caused by this, if a foreign object pierces the belt and the wire breaks at the same time, there is a delay timer even if the switch is turned on. The on signal is not detected, and as a result, the vertical tear cannot be detected.

In this way, with a configuration that detects longitudinal tears in the belt by the tensile force acting on the wire, malfunctions or detection may not be possible.Therefore, in this invention, we have developed a system that accurately responds to the various situations described above and prevents malfunctions. It is an object of the present invention to provide a device that can reliably detect longitudinal tears in a belt without causing any damage.

Means for Solving the Problems In order to achieve the above-mentioned object, this invention uses a wire stretched on the underside of the conveyor belt in a direction crossing the running direction of the conveyor belt, and a first detector that outputs a signal based on a displacement associated with an increase in the tension of the wire; a second detector that outputs a signal based on a displacement associated with a decrease in the tension of the wire; first timer means for outputting an alarm signal when the signal is continuously output for a period of time or more;
a second timer means that is turned on by the output signal from the first detector and continues to output the signal for a preset time even after the output signal stops;
The apparatus is characterized by comprising an alarm signal output means for outputting an alarm signal based on both the output signal from the second detector and the output signal from the second timer means.

Function: Therefore, in the device of this invention, when a heavy object pierces the belt, the heavy object travels with the belt and gets caught on the wire, and as a result, the wire is pulled and displaced, so that the first detector is detected. outputs a signal, and since that state continues, the first timer means outputs an alarm signal. In addition, if the tension applied to the wire becomes excessive and the wire breaks at the same time as a heavy object pierces the belt, the output signal of the first detector will not continue for the preset time, so the first timer means will output an alarm signal. However, even if the first detector once outputs a signal and then stops outputting the signal, the second timer means outputs the signal for a preset time, and the tension decreases due to the wire cutting and the accompanying Since the second detector outputs a signal due to the displacement, the alarm signal output means outputs an alarm signal. Furthermore, if the wire is bent by a large impact force or vibration, and the tension increases temporarily, only the first detector will temporarily output a signal, but that output will continue for more than a preset time. Therefore, the first timer means does not output an alarm signal. In this case, naturally, the alarm signal output means also does not output an alarm signal. Also, if the wire becomes loose due to long-term use or repeated loads, the second detector may output a signal due to the displacement due to the decrease in wire tension, but the alarm signal Since the output means does not operate solely by the signal from the second detector, no alarm signal is output. That is, depending on the manner in which tension is applied to the wire, it is possible to determine whether a heavy object is stuck into the belt or other conditions.

Embodiments Hereinafter, embodiments of this invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing an embodiment of this invention, in which a wire 2 forming a part of a sensor is installed on the lower surface side of the belt 1 of the receiving conveyor at the intersection chute of the belt conveyor. It is stretched along the direction that intersects the direction. That is, the belt 1 is supported by a roller (not shown) so that the middle part in the width direction is slightly depressed, and the wire 2 has one end connected to a tension detector 3 as a first detector. The other end is fixed to a predetermined fixed part 4 such as a bracket or frame through the second end.
The wire is stretched by being fixed to the fixed part 4 via a wire breakage detector 5, which is a detector, and the metal wire is attached to the support metal 6 so that the middle part of the wire 2 is almost parallel to the lower surface of the belt 1. It has been lowered by 7.

The tension detector 3 operates and outputs a signal when a tension above a certain level is applied to the wire 2, and an example thereof is shown in FIG. 2. That is, the rod 8 to which one end of the wire 2 is attached is inserted and held in the bracket 9 so as to be movable back and forth.
A dog plate 10 is attached to the middle part of the rod 8, and a compression spring 12 is arranged between the dog plate 10 and the front plate 11 of the bracket 9.
A limit switch 13 that is turned on by a dog plate 10 is attached to the switch.
Therefore, tension is applied to wire 2 and rod 8
As the limit switch 13 moves forward against the compression spring 12, the limit switch 13 moves against the dog plate 10.
It is designed to be turned on by the switch.
If a normally closed contact switch is used instead of the limit switch 13, the normally closed contact switch is attached to the rear plate 14 of the bracket 9, and the normally closed contact switch is normally pressed by the dog plate 10. Then, when tension is applied to the wire 2 and the dog plate 10 moves forward together with the rod 8, the contact of the normally closed contact switch may be closed.

On the other hand, the wire breakage detector 5 operates and outputs a signal when the tension of the wire 2 is reduced, such as when the wire 2 is broken, and an example thereof is shown in FIG.
That is, the wire breakage detector 5 shown here is configured to turn on when tension is no longer applied to the wire 2, contrary to the tension detector 3 described above, and when the rod 15 to which the other end of the wire 2 is attached is turned on. It is inserted and held in the bracket 16 so as to be movable back and forth.
A dog plate 17 is fixed to the middle part of the rod 15, and the rod 15 is fixed between the dog plate 17 and the front plate 18 of the bracket 16.
A compression spring 19 is disposed which acts to retract the bracket 16, and a limit switch 21 which is turned on by the dog plate 17 is attached to the rear plate 20 of the bracket 16. Therefore, the wire breakage detector 5 detects when the wire 2 is broken.
By retracting the dog plate 17 together with the rod 15 by the compression spring 19,
The dog plate 17 is configured to press the limit switch 21 to turn it on. Note that when a normally closed contact switch is used in place of the limit switch 21, it is only necessary to make changes such as attaching the normally closed contact switch to the front plate 18 of the bracket 16, as described for the tension detector 3 above. It is similar to

Limit switches 13 and 21 in each of the detectors 3 and 5 are connected to a controller 22 that determines longitudinal tearing of the belt 2 based on the on-state of the limit switches. FIG. 4 is a circuit diagram showing an example of the controller 22, in which the limit switch (hereinafter referred to as the first switch) 13 of the tension detector ₃ is turned on when a predetermined set time T1 has elapsed. A time-limited operation timer 23, which is a first timer means that outputs an ON signal, and an instantaneous operation timer 23, which is a second timer means that outputs an ON signal after maintaining the ON state for a predetermined set time _T2 even after the OFF operation. It is connected in parallel with the recovery timer 24. Further, the output end of the instantaneous operation time limit return timer 24 and the limit switch (hereinafter referred to as a second switch) 21 of the disconnection detector 5 are connected to an AND circuit 25 which is an alarm signal output means, and the AND circuit 25 output terminal and the time-limited operation timer 2
3 is connected to the OR circuit 26,
The output end of the OR circuit 26 is connected via a self-holding circuit 27 to appropriate longitudinal tear alarm means (not shown).

Further, the first switch 13 is the timer 2
Self-holding circuit 28 placed in parallel with 3 and 24
Through the wire press down occurrence indicator (not shown)
The second switch 21 is further connected to a wire breakage indicator (not shown) via another self-holding circuit 29.

Next, the operation of the above device will be explained for each assumed case. First, when a large impact occurs due to a heavy object falling and the wire 2 is temporarily pushed up, the tension applied to the wire 2 increases temporarily, so that the dog plate 10 of the tension detector 3 is pushed up against the rod 8. move forward and turn the first switch 13
is temporarily turned on, but the time-limited operation timer 23 does not output an on signal because the first switch 13 is turned off before the set time _T1 elapses. In addition, the instantaneous operation time limit return timer 24
switches to the on state with the on operation of the first switch 13, and remains on for the set time _T2 after the first switch 13 is turned off, but since the wire 2 is not cut, the second switch 21
is off, the AND circuit 25 does not output a signal. That is, since no signal is input to the OR circuit 26 from either the time-limited operation timer 23 or the AND circuit 25, no signal is output from the OR circuit 26 to the vertical tear occurrence alarm means. Therefore, in this case, a signal is outputted only to the wire push-down occurrence indicator via the self-holding circuit 28.

Also, a fallen heavy object pierces belt 1,
When this moves together with the belt 1 and applies a tensile force to the wire 2, the first switch 13 remains on, so the time-limited operation timer 23 outputs an on signal after the set time elapses, and as a result , the OR circuit 26 outputs a signal to the vertical tear occurrence alarm means, and the output state is maintained by the self-holding circuit 27.

If a fallen heavy object pierces the belt 1 and the wire 2 breaks at the same time, the first switch 13 will temporarily turn on, but will immediately return to the off state when the wire 2 is cut, so it will operate for a limited time. The timer 23 does not output an on signal. On the other hand, the instantaneous operation time-limited return timer 24 maintains the on state and continues outputting the signal for the set time _T2 after the first switch 13 is turned on. Furthermore, in the wire breakage detector 5, since the force that pulls the rod 15 to the forward position is no longer applied due to the wire 2 being cut, the dog plate 17 is pushed back together with the rod 15 by the compression spring 19, and the second The switch 21 is pressed by the dog plate 17 and turned on. Therefore, the AND circuit 25 outputs a signal based on the input signals from the instantaneous operation time limit return timer 24 and the second switch 21, and as a result, the OR circuit 26 outputs a signal to the vertical tear occurrence alarm means, and the output thereof A self-holding circuit 27 maintains the state.

Furthermore, if the wire 2 is cut or loosened due to vibration or the like, the tension applied to the wire 2 does not particularly increase, so the first switch 13 remains in the OFF state, whereas the second switch 21 The ON operation occurs when the tension applied to 2 is removed. Therefore, only the second switch 21 operates, its output signal is sent to the wire breakage indicator, and its output state is transmitted to the self-holding circuit 2.
Maintained by 9.

As mentioned above, when the wire 2 is pulled due to a heavy object piercing the belt 1 and is cut immediately after the tension, a signal is output to the vertical tear warning means, and other wires 2 are temporarily depressed. Or in the case of a simple cut, no signal is output to the vertical tear occurrence warning means, so that the vertical tear can be reliably detected without causing any malfunction.

Effects of the invention As is clear from the above explanation, the device of this invention has first and second detectors for detecting tension and relaxation of the wire, and a continuous state of signal output from these detectors. first and second timer means for outputting a signal based on the
Since the alarm signal output means is provided which is activated by the signal from the detector and the second timer means, it is possible to clearly distinguish between situations that cause longitudinal tearing of the belt and other situations. Vertical tearing of a belt can be reliably detected without causing malfunction.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing one embodiment of this invention, Fig. 2 is a sectional view showing an example of the tensile detector, and Fig. 3 is a schematic diagram showing an example of this device.
The figure is a sectional view showing an example of a disconnection detector, and FIG. 4 is a circuit diagram showing an example of a controller. 1... Belt, 2... Wire, 3... Tension detector, 5... Disconnection detector, 8, 15... Rod,
10, 17... Dog plate, 13, 21...
Limit switch, 22... Controller, 23... Time-limited operation timer, 24... Instantaneous action time-limited return timer, 25... AND circuit, 26... OR circuit.

Claims (1)

[Scope of utility model registration request] a wire stretched across the lower surface of the conveyor belt in a direction crossing the running direction of the conveyor belt; a first detector that outputs a signal based on displacement of the wire as the tension increases; a second detector that outputs a signal in response to a displacement caused by a decrease in tension; and a second detector that outputs an alarm signal when a signal is continuously output from the first detector for a preset time or more. a first timer means that is turned on by the output signal from the first detector and continues to output the signal for a preset time even after the output signal stops; A longitudinal belt tear detection device comprising: alarm signal output means for outputting an alarm signal based on both the output signal from the detector and the output signal from the second timer means.