JP4962229B2 - How to detect the number of workpieces on the stock conveyor - Google Patents

Description

  The present invention relates to a technique for detecting the number of workpieces on a stock conveyor. Specifically, it is a technique for grasping the number of workpieces on a stock conveyor without increasing the number of sensors.

In a production line, stocking workpieces on a conveyor has been performed for a long time. The length of the conveyor is basically determined by the distance between the facilities. However, when the equipment is in operation, it may be necessary to replace the tool due to wear of the tool or to perform maintenance. In this case, if the stock conveyor is long, the workpiece is stocked on the conveyor. Therefore, if the equipment is restored in a short time, there is an advantage that it is not necessary to stop other equipment.
However, since lengthening the conveyor means increasing the installation area of the production line, it is not necessary to lengthen the conveyor to unnecessarily stock workpieces.

As methods for counting the number of workpieces on the conveyor, methods such as Patent Literature 1 and Patent Literature 2 are disclosed.
Patent Document 1 is a technique for an in-room management system using an optoelectronic sensor, and recognizes the number of people and objects in the room from the number of people and objects entering and leaving the room using a photoelectric tube. The system is disclosed. By providing two sensors at the doorway, the direction of movement of a person or an object can be specified based on the detection timing of the two sensors, so that the number of persons or objects can be accurately counted.

  Patent Document 2 is a technique regarding a tracking method for a tubular steel material conveyance line, and pipe counters CT1 and CT2 are arranged. These counters are cleared when there is no steel pipe in the conveyance line, and are simply counted by passing through the steel pipe. It continues to increase, and returns to 0 when it overflows due to a match with the preset value. At this time, the overflowed number is preset in the counter of the next zone, and is also preset in the counter of the next zone. By doing so, continuous operation is possible even when one of the pipe preset counters is broken, and the location of the failure counter can be specified.

JP 2002-319013 A JP-A-5-8838

However, Patent Literature 1 and Patent Literature 2 are considered to have the following problems.
In Patent Document 1, it is assumed that people and objects enter and exit in a closed space. Therefore, there is a problem that the number of workpieces is deviated in a system in which workpieces may be extracted halfway, such as workpiece conveyors.
Similarly, since Patent Document 2 is not premised on being extracted on the way, there is a problem that the actual number is shifted from the number grasped by the system.

However, in an actual production line, the work on the conveyor is pulled out or returned later for convenience such as quality inspection of products or elimination of NG products. Then, the number of workpieces grasped by the machine and the actual number of workpieces change, and errors are accumulated.
In order to accurately grasp the number of workpieces on the conveyor where such workpiece extraction or the like occurs, conventionally, there has been no choice but to prepare sensors for the number of workpieces that can be loaded on the conveyor. However, increasing the number of sensors leads to an increase in cost, which is not preferable.

The advantage of always accurately grasping the number of workpieces on a plurality of conveyors on the production line is to increase the efficiency of the production line.
By knowing the number of workpieces on multiple conveyors, for example, it is possible to stop the equipment in the downstream process of conveyors with a small number of stocked workpieces for a short time, and perform tool replacement or maintenance. Thus, if the equipment is operated before the work has accumulated on the conveyor, the production line can be operated substantially without being stopped.

  Accordingly, an object of the present invention is to provide a method for detecting the number of workpieces on a stock conveyor capable of accurately grasping the number of workpieces on the stock conveyor in order to solve such a problem.

In order to achieve the above object, the method for detecting the number of workpieces on a stock conveyor according to the present invention has the following characteristics.
(1) In a method for detecting the number of workpieces on a stock conveyor, comprising: a conveyor that conveys workpieces; a first detection sensor that is provided on the conveyor and detects a workpiece-free state; and a second detection sensor that detects a workpiece full state. ,
A workpiece counter that counts the number of workpieces, a first timer that moves in conjunction with the first detection sensor, and a second timer that moves in conjunction with the second detection sensor, wherein the first detection sensor The first timer is triggered by the fact that the workpiece is no longer detected, and when the first timer exceeds a specified time, the count of the workpiece counter is set to 0, and the second detection sensor When the workpiece is detected, the second timer is activated, and when the second timer exceeds a specified time, the count value of the workpiece counter is set to a specified value.

The “no workpiece state” here means a state in which the workpieces stocked on the conveyor no longer exist. In many cases, a sensor for detecting a state in which a workpiece is lost is attached to the exit side of the conveyor. That is, in many cases, the workpiece is detected at the front end portion in the conveyance direction of the workpiece, and if the workpiece cannot be detected, it is determined that there is no workpiece.
In addition, the “work full state” here refers to a state where the maximum number of stocks on the conveyor is reached. In many cases, a sensor that detects a state in which the workpiece is full is attached to the entrance side of the conveyor. That is, in many cases, the workpiece is detected at the rear end portion with respect to the workpiece conveyance direction, and if the workpiece is detected, the “work full state” is determined.

(2) In the method for detecting the number of workpieces on the stock conveyor described in (1),
A production line including a plurality of conveyors includes a display device that receives data from the workpiece counter and displays the number of workpieces, and the display device displays the number of workpieces stocked on the conveyor in real time. It is characterized by.

By the method for detecting the number of workpieces on the stock conveyor according to the present invention having such characteristics, the following operations and effects can be obtained.
First, the invention described in (1) includes a conveyor that conveys a workpiece, a first detection sensor that is provided on the conveyor and detects a workpiece-free state, and a second detection sensor that detects a workpiece full state. In the method for detecting the number of workpieces on a stock conveyor, a workpiece counter for counting the number of workpieces, a first timer that moves in conjunction with the first detection sensor, and a second timer that moves in conjunction with the second detection sensor, When the first detection sensor stops detecting the workpiece, the first timer is activated, and when the first timer exceeds the specified time, the count of the workpiece counter is set to 0, and the second detection sensor When the second timer is triggered by the detection of, and when the second timer exceeds the specified time, the count value of the work counter is set to the specified value. It is possible to accurately grasp the number of work on bare. This is due to the action described below.

As described above, in a conveyor that conveys workpieces, it is relatively frequent in a production line that a workpiece in the middle of conveyance is extracted or the extracted workpiece is returned to the conveyor. This is in order to perform sampling for checking non-defective workpieces and to remove defective products. Therefore, it is desirable to periodically correct the number of workpieces to the correct number.
The first detection sensor is a sensor that detects a “work-free state”, and the second detection sensor is a sensor that detects a “work-full state”. The number of workpieces is counted and corrected using this sensor.

The number of workpieces is counted by detecting a workpiece passing through the second detection sensor, counting up, and detecting a workpiece passing through the first detection sensor. In this way, the number of workpieces can be counted. Further, when the second detection sensor has detected a workpiece exceeding the specified time of the second timer, it is determined as a “work full state” and the number of workpieces is corrected. Further, when the first detection sensor does not detect the work exceeding the specified time of the first timer, it is determined that there is no work, and the number of works is corrected.
The “no workpiece state” or “work full state” occurs many times a day in relation to the previous process and the subsequent process. Therefore, the work counter that counts the number of workpieces on the conveyor is corrected many times a day, so that the number of workpieces on the conveyor can be grasped almost accurately even if it is extracted or increased during the process. It becomes.

The invention described in (2) is a display device for receiving data from a work counter and displaying the number of workpieces in a production line including a plurality of conveyors in the method for detecting the number of workpieces on a stock conveyor described in (1). And the display device displays the number of workpieces stocked on the conveyor in real time, so that it is possible to check how many workpieces are stocked on each conveyor by the display device.
Since the number of workpieces stocked on each conveyor is displayed on the display device, for example, the post-process of the conveyor with a small number of workpiece stocks can be stopped and the blades of the equipment can be replaced.
Since it is not necessary to stop the pre-process of the conveyor as long as the conveyor stock is possible, the time for stopping the production line can be shortened and the productivity of the workpiece can be improved.

Next, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, the schematic diagram of the conveyance conveyor 10 is shown.
The conveyor 10 includes a stock conveyor 20 that connects the pre-process 15 and the post-process 16, and a first detection sensor 31, a second detection sensor 32, an input sensor 33, and a standby sensor 34 that are arranged on the stock conveyor 20.
The stock conveyor 20 may be of any conveying system such as a roller conveyor or a belt conveyor, but in this embodiment, the roller conveyor system is used. With this stock conveyor 20, the workpiece 11 discharged from the previous process 15 can be conveyed to the subsequent process 16.
The workpiece 11 is conveyed in contact with the stock conveyor 20 on the lower surface, and is carried to the post-process 16 in a pressed state. Since a stopper (not shown) is provided at the front end side of the stock conveyor 20, if the workpiece 11 is stopped by the stopper (not shown), the workpiece 11 is pushed by the next workpiece 11 and arranged on the stock conveyor 20.

Up to seven workpieces 11 indicated by broken lines can be stocked on the stock conveyor 20. The workpiece 11 is assumed to be a metal part.
The workpiece 11 on the conveyor 10 is detected by the first detection sensor 31, the second detection sensor 32, the closing sensor 33, and the standby sensor 34. There are no particular limitations on the type of sensor, but it is preferable to use it properly depending on the environment in which it is used, such as proximity sensors, limit switches, and phototubes. In this embodiment, since the workpiece 11 is made of metal, a proximity sensor is used for detection.

The first detection sensor 31 is a sensor that detects the workpiece 11 on the stock conveyor 20, and is disposed at the tip of the stock conveyor 20. While the first detection sensor 31 is detecting the workpiece 11, it means that the workpiece 11 is stocked on the stock conveyor 20. Therefore, when the first detection sensor 31 cannot detect the workpiece 11 for a predetermined time or more, it means that the workpiece 11 is not stocked on the stock conveyor 20. That is, it is a “no work state”.
The second detection sensor 32 is a sensor that detects the workpiece 11 on the stock conveyor 20, and is disposed at the rear part of the stock conveyor 20. If the second detection sensor 32 continues to detect the workpiece 11 for a certain time or more, it means that the workpiece 11 can no longer be stocked on the stock conveyor 20. That is, the “work full state”.
The first detection sensor 31 and the second detection sensor 32 are provided as standard if the stock conveyor 20 performs general workpiece conveyance.
The input sensor 33 and the standby sensor 34 are provided in the pre-process 15 and the post-process 16, respectively, and can detect the workpiece 11 in the same manner as the first detection sensor 31 and the second detection sensor 32.

In FIG. 2, the screen of ANDON 40 showing the state of the production line 50 is shown.
The ANDON 40 is a display device that shows the operating status of the production line 50, and is used by an operator to grasp the state of the production line 50.
The ANDON 40 displays a rough layout of the production line 50 and the number of workpieces 11 stocked on the first stock conveyor 21, the second stock conveyor 22, the third stock conveyor 23, and the fourth stock conveyor 24. ing. The configuration of the first stock conveyor 21 to the fourth stock conveyor 24 is substantially the same as that of the stock conveyor 20 shown in FIG. However, the length and shape of the stock conveyor 20 differ depending on the arrangement of the pre-process 15 and the post-process 16.
In addition to this, the ANDON 40 connected to an ANDON control device (not shown) indicates the operating status of the facilities of the production line 50 and the like.

Since the production line 50 of the present embodiment has such a configuration, the following operation is demonstrated.
In FIG. 3, the main flow of the conveyance conveyor 10 is shown. 4 and 5 show a subroutine flow of the transfer conveyor 10. The contents will be described below.
In S1, the work counter is reset. A control panel (not shown) for controlling the stock conveyor 20 is provided with a sequencer in which a data link is formed with ANDON 40, and the work 11 is counted therein. The work counter of this embodiment has a minimum value of 0 and a maximum value of 7. Then, the process proceeds to S2.
In S2, a subroutine for checking the first detection sensor 31 is executed. This subroutine will be described later with reference to FIG. Then, the process proceeds to S3.

In S3, a subroutine for checking the second detection sensor 32 is executed. This subroutine will be described later with reference to FIG. Then, the process proceeds to S4.
In S4, it is confirmed whether the stock conveyor 20 complete | finishes a process. If the process is to be ended (S4: Yes), the flow is ended. If the process is to be continued (S4: No), the process proceeds to S1.
Substantially, the process ends in S4 when the equipment is stopped, and therefore the first detection sensor 31 and the second detection sensor 32 are repeatedly checked.
In addition, regarding operation | movement of the stock conveyor 20, although another operation | movement, such as a conveyance stop of the stock conveyor 20, may be required, it is not considered in this embodiment.

Next, a subroutine for checking the first detection sensor 31 shown in FIG. 4 will be described.
In S10, it is checked whether or not the first detection sensor 31 is OFF. If the first detection sensor 31 is detecting the workpiece 11 (S10: No), the flow is terminated and the process returns to the main flow. If the first detection sensor 31 does not detect the workpiece 11 (S10: Yes), the process proceeds to S11.
In S11, the first timer is reset. The first timer is a timer that works in conjunction with the first detection sensor 31. Then, the process proceeds to S12.
In S12, the first timer starts counting. Then, the process proceeds to S13.
In S13, it is checked whether the value of the first timer exceeds the set value. The setting value here is a setting value for determining the “no-work state”, and is referred to as a first setting value for distinction. If the value of the first timer exceeds the first set value (S13: Yes), the process proceeds to S16. If the value of the first timer does not exceed the first set value (S13: No), the process proceeds to S14.

The first timer starts counting in S12 when the first detection sensor 31 does not detect the workpiece 11 in S10. Here, the behavior of the workpiece 11 on the stock conveyor 20 detected by the first detection sensor 31 can be considered as two patterns. One is a pattern in which there is no work 11 stocked on the stock conveyor 20 and the first detection sensor 31 cannot detect the work 11. The other is a pattern in which the workpiece 11 is stocked on the stock conveyor 20 and the gap between the workpiece 11 and the next workpiece 11 is detected when the workpiece 11 moves to the subsequent process 16.
When the state in which the first detection sensor 31 does not detect the workpiece 11 continues, it can be determined that the “no workpiece state”. The first timer and the first set value are provided for determining the threshold value. The first set value depends on the speed of the stock conveyor 20 and the like, and should be appropriately selected.

In S14, it is checked whether or not the first detection sensor 31 is turned on. If the first detection sensor 31 detects the workpiece 11 and turns on (S14: Yes), the process proceeds to S15. If not ON (S14: No), the process proceeds to S13.
Here, the fact that the first detection sensor 31 detects the workpiece 11 and is turned on indicates that the value of the first timer is equal to or less than the first set value in S13, and thus the workpiece 11 is placed on the stock conveyor 20. Is stocked and the workpiece 11 is passing.
In S15, the work counter is counted down. Then, the flow ends and the process returns to the main flow. Passing through S15 means that one or more workpieces 11 have been stocked on the stock conveyor 20, so the workpiece 11 has passed the position of the first detection sensor 31, and the stock on the stock conveyor 20 has decreased by one. To do. Therefore, it is only necessary to simply count down the work counter.

In S16, the work counter is cleared. Then, the flow ends and the process returns to the main flow. Passing through S16 means that the stock conveyor 20 is in the “no workpiece state”. The number of the work counter should be 0 when in the “no work state”. Therefore, the work counter value is cleared. At this time, if the value of the work counter is not 0, the value of the work counter is corrected.
In this way, the sensor check of the first detection sensor 31 shown in FIG. 4 is performed, and it is confirmed that the “work-free state” is confirmed and the work counter value is cleared. It becomes possible to correct at the timing.

Next, a subroutine for checking the second detection sensor 32 shown in FIG. 5 will be described.
In S20, it is checked whether or not the second detection sensor 32 has detected the workpiece 11. If the second detection sensor 32 is detecting the workpiece 11 (S20: Yes), the process proceeds to S21. If the 2nd detection sensor 32 does not detect the workpiece | work 11 (S20: No), a flow will be complete | finished and it will return to a main flow.
In S21, the second timer is reset. The second timer is a timer that is linked to the second detection sensor 32. Then, the process proceeds to S22.
In S22, the second timer starts counting. Then, the process proceeds to S23.
In S23, it is checked whether or not the value of the second timer exceeds the set value. The set value here is a set value for determining the “work full state”, and is referred to as a second set value for distinction. If the value of the second timer exceeds the second set value (S23: Yes), the process proceeds to S26. If the value of the second timer does not exceed the second set value (S23: No), the process proceeds to S24.

The second timer starts counting in S22 when the second detection sensor 32 detects the workpiece 11 in S20. Here, the behavior of the workpiece 11 on the stock conveyor 20 detected by the second detection sensor 32 can be considered as two patterns. One is a pattern in which the work 11 on the stock conveyor 20 is fully loaded, and the second detection sensor 32 continues to detect the work 11. The other is a pattern in which the work 11 is few on the stock conveyor 20 and the work 11 immediately passes through the detection position of the second detection sensor 32.
When the second detection sensor 32 continues to detect the workpiece 11, it can be determined that the state is the “full workpiece state”. A second timer and a second set value are provided for determining the threshold. The second set value depends on the speed of the stock conveyor 20 and the like, and should be appropriately selected.

In S24, it is checked whether or not the second detection sensor 32 is turned off. If the second detection sensor 32 does not detect the workpiece 11 and is turned OFF (S24: Yes), the process proceeds to S25. If not OFF (S24: No), the process proceeds to S23.
Here, the fact that the second detection sensor 32 does not detect the workpiece 11 and is turned OFF means that the value of the second timer is less than or equal to the second set value in S23, so that the workpiece 11 is placed on the stock conveyor 20. Means not full.
In S25, the work counter is counted up. Then, the flow ends and the process returns to the main flow. The passage through S25 means that the workpiece 11 can still be stocked on the stock conveyor 20, the workpiece 11 has passed the position of the second detection sensor 32, and the workpiece 11 has been added to the stock conveyor 20 by one. Therefore, the work counter is simply counted up.

In S26, the work counter value is corrected. Then, the flow ends and the process returns to the main flow. Passing through S26 means that the stock conveyor 20 is in the “work full state”. Since the maximum number of workpieces is set to 7 in the stock conveyor 20 of the present embodiment, the number of the workpiece counter should be 7 when in the “work full state”. Therefore, the value of the work counter is set to 7. At this time, if the value of the work counter is not 7, the value of the work counter is corrected.
Thus, if the sensor check of the second detection sensor 32 shown in FIG. 5 is performed to confirm that the “work full state” is confirmed and the work counter value is corrected, the work counter value is changed to “work full state”. It becomes possible to correct at the timing.

In this way, the work 11 of the stock conveyor 20 is confirmed by the work counter and corrected at the timing shown in FIG. 4 or FIG. The numbers are displayed on the ANDON 40 as shown in FIG. 2 in real time.
Therefore, the number of workpieces 11 on the first stock conveyor 21, the second stock conveyor 22, the third stock conveyor 23, and the fourth stock conveyor 24 is displayed on the ANDON 40, and the operator views the ANDON 40. The operating status of the production line 50 can be confirmed.
Needless to say, whether or not each line, which is a general function of the ANDON 40, is in operation is also displayed.

Since the production line 50 of this embodiment has the above-described configuration and exhibits the above-described operation, the following effects can be obtained.
The first effect is that the number of workpieces 11 on the stock conveyor 20 can be accurately grasped.
Stock comprising a stock conveyor 20 that conveys the workpiece 11, a first detection sensor 31 that is provided on the stock conveyor 20 and that detects a "no workpiece state", and a second detection sensor 32 that detects a "work full state". In the method of detecting the number of workpieces on the conveyor, a workpiece counter that counts the number of workpieces 11, a first timer that moves in conjunction with the first detection sensor 31, and a second timer that moves in conjunction with the second detection sensor 32. The first timer is triggered when the first detection sensor 31 no longer detects the workpiece 11, and when the first timer exceeds the first set value, the count of the workpiece counter is set to 0 ( (S16), triggered by the detection of the workpiece 11 by the second detection sensor 32, the second timer is activated and the second timer exceeds the second set value. At the time the, since the count of the work counter a specified value (carried out at S26), it is possible to accurately grasp the number of work on the stock conveyor 20.

Basically, the workpiece 11 stocked on the stock conveyor 20 is supplied from the pre-process 15 and conveyed to the post-process 16. However, there are not a few cases in which the workpiece 11 is extracted except for detection of defective products of the workpiece 11 and sampling of the workpiece 11.
Further, the work 11 may still be returned to the stock conveyor 20.
Therefore, simply using a work counter, counting down when passing the first detection sensor 31, counting up when passing the second detection sensor 32, the number of workpieces 11 stocked on the actual stock conveyor 20, The number of the work counter displayed on ANDON 40 is different.

However, if efficiency of the production line 50 is considered, the line stop time needs to be kept to a minimum. Therefore, the work counter is corrected in the two states of “no work state” and “work full state”. In the “no workpiece state” and “work full state”, the number of each workpiece is determined.
In the “no workpiece state”, there should be no workpiece 11 stocked on the stock conveyor 20.
In the “work full state”, the number of works 11 stocked on the stock conveyor 20 should be seven.
In each state, the work 11 stocked on the stock conveyor 20 is determined, and by correcting to the number, the work counter number can hold the correct value.

It has been confirmed by the applicant that the “work full state” and the “no workpiece state” occur relatively well in the actual production line 50 due to the relationship between the previous process and the subsequent process. Therefore, the work counter is periodically corrected, and the number displayed on the ANDON 40 maintains a substantially correct value, so that there is no significant difference from the number of the work 11 actually stocked.
By performing such control, the number of workpieces 11 on the stock conveyor 20 can be correctly grasped even in a remote place.

As a second effect, the production line 50 provided with a plurality of stock conveyors 20 is provided with ANDON 40 that receives data from the work counter and displays the number of workpieces 11. Since the number of 11 is displayed in real time, it is possible to grasp the state of the production line 50 even in a remote place.
The ANDON 40 was originally developed as a means for knowing the operating state of the production line 50. This is for improving the productivity of the production line 50. If an abnormality occurs, the production line 50 is stopped and the abnormal part is immediately corrected.
By doing so, it is possible to prevent the work 11 from being defective, and as a result, the productivity of the production line 50 can be improved.
In this embodiment, the function of the ANDON 40 is expanded, and the number of workpieces 11 stocked on the first stock conveyor 21 to the fourth stock conveyor 24 is displayed on the ANDON 40. The time can be shortened.

In maintaining the production line 50, it is necessary to periodically perform maintenance of a processing machine or the like installed in a pre-process or a post-process of the stock conveyor 20. For example, if the machine uses a blade such as a cutting machine, the blade must be replaced.
As described above, it is desirable that the work necessary for maintaining the production line 50 is completed in a relatively short time without stopping the production line 50 as much as possible.
If the number of the workpiece | work 11 stocked by the 1st stock conveyor 21 thru | or the 4th stock conveyor 24 by ANDON 40 is shown, it can use as a standard which performs such an operation | work.

For example, if the first stock conveyor 21 is in the “work full state”, the subsequent process of the first stock conveyor 21 is performed on the first stock conveyor 21 even if the previous process of the first stock conveyor 21 is stopped. The production of the workpieces 11 can be continued for a time obtained by multiplying the number of workpieces 11 stocked by the tact time of the subsequent process. If the tact time of the post-process is 1 minute and the number of workpieces 11 stocked on the first stock conveyor 21 is 7, it is not necessary to stop the pre-process for 7 minutes.
Further, for example, if the third stock conveyor 23 is in the “no workpiece state”, even if the work is stopped after the third stock conveyor 23 is stopped, the previous process of the third stock conveyor 23 is the third stock conveyor 23. The production of the workpieces 11 can be continued during the time obtained by multiplying the number of workpieces 11 that can be stocked by the tact time of the previous process.

Conventionally, in such work, an operator walks through the inside of the production line 50, and the worker comprehensively determines the state of the production line 50 and determines a part to be maintained. This is the know-how of an experienced worker, and if the worker's judgment is appropriate, the productivity of the production line 50 is not lowered.
The ANDON 40 of the present embodiment helps such a determination, and at least the time for the operator to walk around the factory in order to grasp the state of the production line 50 can be shortened. As a result, it contributes to further improving the productivity of the production line 50.

Further, as a third effect, even if the control of the present embodiment is added to the conventional production line 50, there is a point that almost no cost is incurred.
Conventionally, a first detection sensor 31 and a second detection sensor 32 are prepared in the stock conveyor 20 installed in the first stock conveyor 21 to the fourth stock conveyor 24 in the past.
This is because it is necessary to control the pre-process 15 and the post-process 16. In order to control the stock conveyor 20, a control panel (not shown) having a sequencer is prepared, and a timer and counter function are provided. Communication between the control panel (not shown) and ANDON 40 is also performed.

Therefore, it can be realized by incorporating a program for controlling the number of workpieces on the stock conveyor 20 of this embodiment into the control panel for controlling the ANDON 40 or the sequencer of the control panel for controlling the stock conveyor 20. . In other words, it is not necessary to process equipment or add a sensor with only the number of steps for adding a program.
As another method for detecting the number of workpieces 11 stocked on the stock conveyor 20, a method of providing the same number of detection sensors as the stockable workpieces 11 on the stock conveyor 20 as described above can be considered.

If an error in the number of workpieces 11 is not always allowed, there is an advantage of preparing detection sensors as many as the number of workpieces 11 that can be stocked. However, it is not necessary to strictly grasp the number of workpieces 11 as long as it is an application for grasping the outline of the production status of the production line 50.
In some cases, an expensive detection sensor is used depending on the use environment. Moreover, if there are many stocks of the workpiece | work 11 on the stock conveyor 20, there also exists a problem that cost will increase by that much. As the number of sensors increases, the maintenance effort also increases.
Therefore, according to the work 11 detection method on the stock conveyor 20 of this embodiment, since the number of the works 11 on the stock conveyor 20 can be grasped by a simple method, the cost merit is high.

Although the invention has been described according to the present embodiment, the invention is not limited to the embodiment, and by appropriately changing a part of the configuration without departing from the spirit of the invention. It can also be implemented.
For example, the flow shown in FIGS. 3 to 5 of the present embodiment is merely an example, and does not prevent adding processing or changing the order as appropriate.
Further, the screen of ANDON 40 shown in FIG. 2 is also an example, and is not limited to this.

The schematic diagram of the conveyance conveyor 10 of this embodiment is shown. The screen of ANDON 40 showing the state of the production line 50 of this embodiment is shown. The main flow of the conveyance conveyor 10 of this embodiment is shown. The subroutine which performs the check of the 1st detection sensor 31 of this embodiment is shown. The subroutine which checks the 2nd detection sensor 32 of this embodiment is shown.

Explanation of symbols

10 Conveyor 11 Work 15 Pre-process 16 Post-process 20 Stock conveyor 21 First stock conveyor 22 Second stock conveyor 23 Third stock conveyor 24 Fourth stock conveyor 31 First detection sensor 32 Second detection sensor 33 Input sensor 34 Standby sensor 40 ANDON 50 production line

Claims (2)

In a method for detecting the number of workpieces on a stock conveyor, comprising: a conveyor that conveys workpieces; a first detection sensor that is provided on the conveyor and detects a workpiece-free state; and a second detection sensor that detects a workpiece full state.
A work counter for counting the number of the workpieces;
A first timer that moves in conjunction with the first detection sensor;
A second timer that moves in conjunction with the second detection sensor,
When the first detection sensor no longer detects the workpiece, the first timer is activated, and when the first timer exceeds a specified time, the count of the workpiece counter is set to 0,
Triggered by the detection of the workpiece by the second detection sensor, when the second timer is activated and the second timer exceeds a specified time, the count value of the workpiece counter is set to a specified value. A method for detecting the number of workpieces on a stock conveyor. In the method of detecting the number of workpieces on a stock conveyor according to claim 1,
A production line including a plurality of the conveyors includes a display device that receives data from the work counter and displays the number of works.
A method for detecting the number of workpieces on a stock conveyor, wherein the display device displays the number of workpieces stocked on the conveyor in real time.

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