WO2021100403A1

WO2021100403A1 - Work system

Info

Publication number: WO2021100403A1
Application number: PCT/JP2020/039728
Authority: WO
Inventors: 匡隆池尻
Original assignee: 日本電産株式会社
Priority date: 2019-11-20
Filing date: 2020-10-22
Publication date: 2021-05-27
Also published as: CN114728380A; CN114728380B; JPWO2021100403A1

Abstract

[Problem] To provide a work system with which both an improvement in work efficiency and suppression of a deterioration in work accuracy can be achieved simultaneously. [Solution] A work system 1 is provided with seven jigs 21 to 27, a workpiece position detection camera 30, a welding torch 40, a control unit 60, and a storage unit 70. The storage unit 70 stores an expected amount of deviation of a placed workpiece W1 from a reference placement position, for each jig 21 to 27. The workpiece position detection camera 30 detects the actual placement position of the workpiece W1 placed in each jig 21 to 27. The control unit 60 controls the welding torch 40 on the basis of the expected amount of deviation if welding work is to be performed with a good jig from among the jigs 21 to 27. The control unit 60 controls the welding torch 40 on the basis of the actual amount of deviation of the actual placement position from the reference placement position, detected by the workpiece position detection camera 30, if welding work is to be performed with a defective jig from among the jigs 21 to 27.

Description

Work system

The present invention relates to a work system.

Conventionally, a so-called free flow type or index type in which a predetermined work is performed on a work object (hereinafter referred to as "work") placed on a plurality of jigs that continuously circulate a predetermined path, etc. Work system is known. Predetermined operations include, for example, various operations such as assembly, assembly, welding, length measurement, and various types of processing.

Work on the work is performed based on the reference placement position of the work on each jig. However, since the work is positioned with respect to the jig by a method such as pressing the work against a predetermined portion of the jig, the actual mounting position of the work tends to deviate from the reference mounting position. Not only that, the actual amount of deviation of the actual mounting position from the reference mounting position differs for each jig. Therefore, it is necessary to grasp the actual mounting position of the work for each jig.

Here, it is conceivable to detect the actual mounting position of the work with a camera or the like before performing the work on the work, and correct the work position based on the actual deviation amount of the work. However, if the actual mounting position of the work is detected every time the work is performed on the work, the work efficiency is lowered.

Therefore, as described in Patent Document 1, the expected deviation amount expected from the actual deviation amount measured for each jig in advance is stored, and the work is placed when the work is performed on the work. Correcting the work position based on the amount of misalignment associated with the jig is effective in improving work efficiency.

Japanese Publication: Japanese Patent Application Laid-Open No. 2004-516480

However, if a defect occurs in the jig itself and the work position is continuously corrected based on the estimated deviation amount, the defective jig will continue to produce a finished product with low work accuracy.

An object of the present invention is to provide a work system capable of both improving work efficiency and suppressing deterioration of work accuracy.

The work system according to one aspect of the present invention includes a plurality of jigs, a work unit, a control unit, a storage unit, and a detection unit. The working unit works on the work object placed on each of the plurality of jigs. The control unit controls the work unit. The storage unit stores the estimated deviation amount of the work object to be mounted from the reference mounting position for each of the plurality of jigs. The detection unit detects the actual mounting position of the work object mounted on each of the plurality of jigs. When the work is performed on at least one good jig that is determined to have a good evaluation of the work among the plurality of jigs, the control unit controls the work unit based on the estimated deviation amount. When work is performed on a defective jig that is determined to have a poor work evaluation among a plurality of jigs, the control unit actually deviates from the reference mounting position of the actual mounting position detected by the detection unit. Control the work area based on the quantity.

The present invention can provide, for example, a work system capable of both improving work efficiency and suppressing a decrease in work accuracy.

FIG. 1 is a side view schematically showing a work system according to an embodiment. FIG. 2 is a flow chart for explaining the control operation by the control unit during the learning period. FIG. 3 is a flow chart for explaining the control operation by the control unit during the operation period. FIG. 4 is a flow chart for explaining the cause analysis operation of the work defect by the control unit.

(Working system 1)
FIG. 1 is a side view schematically showing the work system 1 according to the embodiment.

The work system 1 is a so-called free flow type work system. In the work system 1, welding work (an example of "predetermined work") is performed on the work object (hereinafter referred to as "work") W1 placed on the seven jigs 21 to 27 to complete the finished product. W2 is produced.

The work system 1 includes a free-flow conveyor 10, seven jigs 21 to 27 (an example of "plurality of jigs"), a work position detection camera 30 (an example of a "detection unit"), and a welding torch 40 ("work unit"). An example), an inspection camera 50, a control unit 60, and a storage unit 70. In this embodiment, seven jigs 21 to 27 are used, but the number of jigs is not limited.

The free flow conveyor 10 continuously conveys each jig 21 to 27. The jigs 21 to 27 are arranged in order on the free flow conveyor 10 at predetermined intervals. Each jig 21 to 27 is attached to the free flow conveyor 10 in a positioned state.

The free flow conveyor 10 includes a transport path 11 and a return path 12. Each jig 21 to 27 moves on the transport path 11 in a predetermined transport direction, and then moves on the return path 12 in a predetermined return direction. The jigs 21 to 27 move on the return path 12 in a predetermined return direction, and then are returned to the transfer path 11.

The loading station ST1, the standby station ST2, the working station ST3, the inspection station ST4, and the discharging station ST5 are sequentially provided in the transport path 11 from the upstream side to the downstream side in the transport direction. The transport path 11 is intermittently driven so that the jigs 21 to 27 are temporarily stopped at the stations ST1 to ST7. The distance that the transport path 11 moves in one drive is the same as the distance between the stations ST1 to ST7. Therefore, the jigs 21 to 27 move from the upstream side to the downstream side along the transport direction while sequentially stopping at the stations ST1 to ST7.

At the mounting station ST1, the work W1 is mounted on each jig 21 to 27. At this time, the work W1 is positioned by being pressed against a predetermined portion of each jig 21 to 27.

At the standby station ST2, the work W1 is temporarily put on standby until each of the jigs 21 to 27 on which the work W1 is placed moves to the work station ST3. A work position detection camera 30 is installed above the standby station ST2. The work position detection camera 30 can detect the actual mounting position of the work W1 on the jigs 21 to 27 by photographing the work W1 mounted on the jigs 21 to 27. The work position detection camera 30 is controlled by the control unit 60.

At the work station ST3, welding work is performed on the work W1 placed on the jigs 21 to 27. A welding torch 40 is arranged at the work station ST3. When the welding torch 40 performs welding work on the work W1, the finished product W2 is produced. In FIG. 1, a case where welding work is performed at four locations of the work W1 is shown, but the position and size of the welding work are not particularly limited. The welding torch 40 is controlled by the control unit 60.

At the inspection station ST4, the welding position (an example of the working position) of the finished product W2 placed on each jig 21 to 27 is inspected. An inspection camera 50 is installed above the inspection station ST4. The inspection camera 50 detects the welding position in the finished product W2 by taking an image of the finished product W2 placed on each of the jigs 21 to 27. The inspection camera 50 is controlled by the control unit 60.

At the discharge station ST5, the finished product W2 is discharged to the outside from each of the jigs 21 to 27. After the finished product W2 is discharged, the jigs 21 to 27 move to the return path 12.

The control unit 60 appropriately controls the work position detection camera 30, the welding torch 40, and the inspection camera 50. The storage unit 70 stores information about each of the jigs 21 to 27. The control unit 60 is connected to the storage unit 70.

Hereinafter, the control by the control unit 60 will be described.

(Control by the control unit 60 during the learning period)
FIG. 2 is a flow chart for explaining a control operation by the control unit 60 in a predetermined period (hereinafter, referred to as “learning period”) from the start of operation of the work system 1.

In step S1, when the jigs 21 to 27 stop at the standby station ST2, the control unit 60 operates the work position detection camera 30 to actually mount the work W1 on the jigs 21 to 27. Detect the mounting position.

In step S2, the control unit 60 acquires an actual deviation amount indicating the distance from the reference mounting position of the actual mounting position of the work W1 mounted on each jig 21 to 27. The actual displacement amount is represented by the magnitude of the positional deviation of the actual mounting position on the XY plane set in the plan view of the work W1 from the reference mounting position and the vector amount indicating the direction thereof. The actual deviation amount can be obtained, for example, by comparing the captured image of the work W1 with the master image of the reference mounting position.

In step S3, the control unit 60 is at a position where welding work is performed on the work W1 mounted on the jig stopped at the standby station ST2 based on the actual deviation amount acquired in step S2 (hereinafter, "welding work position"). ".) Is decided.

In step S4, when each jig 21 to 27 stops at the work station ST3, the control unit 60 controls each jig 21 to 27 based on the welding work position determined in step S3. Welding work is performed on the work W1 placed on the torch. In this way, during the learning period, welding work is performed on all the jigs 21 to 27 based on the actual displacement amount.

In step S5, when the jigs 21 to 27 stop at the inspection station ST4, the control unit 60 operates the inspection camera 50 to position the finished product W2 mounted on the jigs 21 to 27 at the welding position. Is detected.

In step S6, the control unit 60 determines whether the welding work of the jigs 21 to 27 is good or bad based on the detected welding position of the finished product W2. Specifically, the control unit 60 determines whether or not the welding position of the finished product W2 placed on the jigs 21 to 27 is within a predetermined range. When the welding position of the finished product W2 is within a predetermined range, the control unit 60 determines that the evaluation of the welding work is "good", and determines that the jig on which the finished product W2 is placed is "Ryoji". Certified as "jig". If the welding position of the finished product W2 is not within the predetermined range, the control unit 60 determines that the evaluation of the welding work is "defective", and determines that the jig on which the finished product W2 is placed is "defective". Certified as "jig".

In step S7, the control unit 60 stores each jig 21 to 27 in the storage unit 70 in association with the identification number whether it is a good jig or a bad jig.

In step S8, the control unit 60 is estimated from the reference mounting position of the work W1 mounted on each jig 21 to 27 based on the actual deviation amount of 1 or more acquired for each jig 21 to 27. Get the amount of deviation. The expected deviation amount is the deviation amount that is expected to occur when the work W1 is placed on the jigs 21 to 27. As the expected deviation amount, for example, a vector amount obtained by averaging a vector amount indicating a plurality of actual deviation amounts can be used.

In step S9, the control unit 60 is a distance from the reference mounting position of the work W1 mounted on each jig 21 to 27 based on the actual deviation amount of 1 or more acquired for each jig 21 to 27. Obtain the expected variability that indicates the variability of. The degree of expected variation is represented by an absolute value indicating the degree of variation in the actual amount of deviation. As the degree of expected variation, for example, a predetermined range determined based on the standard deviation σ calculated from a plurality of actual deviation amounts, a maximum value of a plurality of actual deviation amounts, and the like can be used.

In step S10, the control unit 60 stores the expected deviation amount and the expected variation degree in the storage unit 70 in association with the identification number for each of the jigs 21 to 27.

In step S11, the control unit 60 determines whether or not the learning period has ended. If the learning period has not ended, the process returns to step S1. When the learning period ends, the process ends.

(Control by the control unit 60 during the operation period)
FIG. 3 is a flow chart for explaining the control operation by the control unit 60 in the period after the learning period (hereinafter, referred to as “operation period”).

In step S20, the control unit 60 refers to the storage unit 70 and determines whether or not the jig stopped at the standby station ST2 is a good jig.

If it is determined in step S20 that the jig stopped at the standby station ST2 is a good jig, the process proceeds to steps S21 to S24.

In step S21, the control unit 60 deactivates the work position detection camera 30 when the good jig stops at the standby station ST2. That is, the control unit 60 does not detect the actual mounting position of the work W1 mounted on the good jig.

In step S22, the control unit 60 refers to the storage unit 70 and acquires the expected deviation amount of the good jig stopped at the standby station ST2.

In step S23, the control unit 60 determines the welding work position in the work W1 placed on the good jig stopped at the standby station ST2 based on the estimated deviation amount acquired from the storage unit 70.

In step S24, when the good jig stops at the work station ST3, the control unit 60 controls the welding torch 40 based on the welding work position determined in step S23, thereby causing the work W1 mounted on the good jig to control the welding torch 40. Welding work is performed on the surface. After that, the process proceeds to step S31.

On the other hand, if it is determined in step S20 that the jig stopped at the standby station ST2 is not a good jig (that is, it is a defective jig), the process proceeds from step S20 to steps S25 to S30.

In step S25, when the defective jig stops at the standby station ST2, the control unit 60 detects the actual mounting position of the work W1 mounted on the defective jig by operating the work position detection camera 30. ..

In step S26, the control unit 60 acquires an actual deviation amount indicating the distance from the reference mounting position of the actual mounting position of the work W1 mounted on the defective jig.

In step S27, the control unit 60 determines the variation in distance from the reference mounting position of the work W1 mounted on the defective jig based on the actual deviation amount of 1 or more acquired during the operation period of the defective jig. Acquire the actual degree of variation shown. The degree of actual variation is represented by an absolute value indicating the degree of variation in the amount of actual deviation. As the actual variation degree, for example, a predetermined range determined based on the standard deviation σ calculated from the plurality of actual deviation amounts, the maximum value of the plurality of actual deviation amounts, and the like can be used.

In step S28, the control unit 60 stores the defective jig in the storage unit 70 in association with the actual variation degree acquired in step S27 in association with the identification number.

In step S29, the control unit 60 determines the welding work position in the work W1 placed on the defective jig stopped at the standby station ST2 based on the actual deviation amount acquired in step S26.

In step S30, when the defective jig stops at the work station ST3, the control unit 60 controls the welding torch 40 based on the welding work position determined in step S29. As a result, welding work is performed on the work W1 placed on the defective jig. After that, the process proceeds to step S31.

In step S31, when the jigs 21 to 27 (including both good jigs and bad jigs) stop at the inspection station ST4, the control unit 60 operates the inspection camera 50 to operate the jigs 21 to 27. The welding position of the finished product W2 placed on the 27 is detected.

In step S32, the control unit 60 determines whether the welding work of the jigs 21 to 27 is good or bad based on the detected welding position of the finished product W2. Then, as described in step S6 (see FIG. 2), the control unit 60 recertifies the good jig and the bad jig for each of the jigs 21 to 27.

In step S33, the control unit 60 stores each jig 21 to 27 in the storage unit 70 in association with the identification number whether it is a good jig or a bad jig. After that, the process returns to step S20.

As described above, when the welding work is performed on the good jigs 21 to 27 among the jigs 21 to 27 which are judged to have a good evaluation of the welding work, the control unit 60 uses the welding torch 40 based on the estimated deviation amount. Control. On the other hand, when the welding work is performed on the defective jig that is determined to have a poor evaluation of the welding work among the jigs 21 to 27, the control unit 60 actually mounts the work position detected by the work position detection camera 30. The welding torch 40 is controlled based on the actual deviation amount from the reference mounting position of the mounting position.

Therefore, with a good jig, the work efficiency can be improved by performing the welding work using the expected deviation amount without operating the work position detection camera 30. Further, with a defective jig, a decrease in work accuracy can be suppressed by operating the work position detection camera 30 and performing welding work using the actual deviation amount.

(Root cause analysis control of work failure by control unit 60)
FIG. 4 is a flow chart for explaining an operation in which the control unit 60 analyzes the cause of the work defect when a work defect occurs in step S32 (see FIG. 3) during the operation period.

In step S41, the control unit 60 refers to the storage unit 70 and acquires the actual variation degree of the defective jig acquired in step S27 (see FIG. 3) during the operation period.

In step S42, the control unit 60 refers to the storage unit 70 and has a probability variation of the defective jig from the probability variation degrees of the jigs 21 to 27 acquired in step S9 (see FIG. 2) during the learning period. Select and get the degree.

In step S43, the control unit 60 arbitrarily selects one good jig (hereinafter, referred to as "specified good jig") from at least one good jig among the jigs 21 to 27.

In step S44, when the specified good jig stops at the standby station ST2, the control unit 60 detects the actual mounting position of the work W1 mounted on the specified good jig by operating the work position detecting camera 30. ..

In step S45, the control unit 60 acquires an actual deviation amount indicating the distance from the reference mounting position of the actual mounting position of the work W1 mounted on the specified good jig.

In step S46, the control unit 60 determines the variation in the distance from the reference mounting position of the work W1 mounted on the specified good jig based on the actual deviation amount of 1 or more acquired during the operation period of the specified good jig. Acquire the actual degree of variation shown.

In step S47, the control unit 60 refers to the storage unit 70 and has a prospective variation of the specified good jig from the prospective variations of the jigs 21 to 27 acquired in step S9 (see FIG. 2) during the learning period. Select and get the degree.

In step S48, the control unit 60 compares the actual variation degree and the expected variation degree of the defective jig, and also compares the actual variation degree and the expected variation degree of the specified good jig. Specifically, the control unit 60 determines whether or not the difference Δ1 between the actual variation degree and the expected variation degree of the defective jig is larger than the first reference value TH1, and also determines the actual variation degree and the expected variation degree of the specified good jig. It is determined whether or not the degree difference Δ2 is larger than the first reference value TH2.

In step S48, when the difference Δ1 for the defective jig is larger than the first reference value TH1 and the difference Δ2 for the specified good jig is equal to or less than the second reference value TH2, a work defect occurs in the defective jig. .. This is because the defective jig cannot accurately position the work W1. Therefore, in step S49, the control unit 60 stops the welding work on the defective jig. In this case, the defective jig may be left attached to the free flow conveyor 10 or may be removed from the free flow conveyor 10 for repair. Even in this case, when the welding work is performed on a good jig other than the defective jig, the control unit has a misunderstanding as described in steps S21 to S24 (see FIG. 3) during the operation period. The welding torch 40 is controlled based on the amount.

In step S48, when the difference Δ1 for the defective jig is larger than the first reference value TH1 and the difference Δ2 for the specified good jig is larger than the second reference value TH2, a work defect occurs in the defective jig. This is not because the defective jig itself is defective, but because another factor on the system has occurred. Therefore, in step S50, when the welding work is performed on the jigs 21 to 27, the control unit 60 is based on the actual deviation amount as described in steps S25 to S30 (see FIG. 3) during the operation period. Controls the welding torch 40.

In step S48, when the difference Δ1 for the defective jig is the first reference value TH1 or less and the difference Δ2 for the specified good jig is the second reference value TH2 or less, a work defect occurs in the defective jig. To do. This is not because the defective jig itself has a defect, but because some sudden and temporary defect has occurred. Therefore, in step S51, when the welding work is performed on the jigs 21 to 27, the control unit 60 is based on the estimated deviation amount as described in steps S21 to S24 (see FIG. 3) during the operation period. Controls the welding torch 40.

As described above, based on the comparison result of the actual variation degree and the expected variation degree of the defective jig, it is possible to easily analyze whether or not the cause of the work defect in the defective jig is the defect of the defective jig itself. ..

In addition, by combining the comparison result of the actual variation and the expected variation of the specified good jig with the comparison result of the actual variation and the expected variation of the defective jig, the cause of the work defect in the defective jig is the defective jig. It is possible to more accurately analyze whether or not there is a problem with itself.

Further, the comparison result between the difference Δ1 between the actual variation and the expected variation of the defective jig and the first reference value TH1, and the difference Δ2 between the actual variation and the expected variation of the specified good jig and the second reference value TH2. By combining with the comparison results, the cause of the occurrence of work defects can be analyzed more accurately and concretely.

(Modified example of the embodiment)
In the above embodiment, the work system 1 is a free flow type, but it may be a so-called index type or the like.

In the above embodiment, in the work system 1, welding work is performed as an example of the work. For example, assembling parts, assembling parts, measuring the length of a predetermined place, and various kinds of processing (cutting processing and surface processing). Etc.).

In the above embodiment, the work system 1 is provided with the welding torch 40 as an example of the work unit, but the work unit is appropriately changed according to the work performed in the work system 1.

In the above embodiment, the work system 1 is provided with the work position detection camera 30 as an example of the detection unit, but the detection unit may be any one capable of detecting the position of the work W1, for example, an infrared imager. There may be.

In the above embodiment, in the work system 1, the welding position (an example of the work position) is inspected by using the inspection camera 50, but the work position may be inspected visually or the like.

10 Free-flow conveyor 21-27 Jig 30 Work position detection camera (an example of "detection unit")
40 Welding torch (an example of "working part")
50 Inspection camera 60 Control unit 70 Storage unit W1 Work object (work)
W2 Finished product ST1 Mounting station ST2 Standby station ST3 Work station ST4 Inspection station ST5 Discharge station

Claims

With multiple jigs
A work unit that performs work on a work object placed on each of the plurality of jigs,
A control unit that controls the work unit and
For each of the plurality of jigs, a storage unit that stores the amount of expected deviation from the reference mounting position of the work object to be mounted, and a storage unit.
A detection unit capable of detecting the actual mounting position of the work object on each of the plurality of jigs, and a detection unit.
With
When the work is performed on at least one good jig determined to have a good evaluation of the work among the plurality of jigs, the control unit controls the work unit based on the expected deviation amount. When the work is performed on the defective jig that is determined to be defective in the evaluation of the work among the plurality of jigs, the reference mounting position of the actual mounting position detected by the detection unit is used. The work unit is controlled based on the actual deviation amount of
Working system.
The storage unit stores whether each of the plurality of jigs is the good jig or the bad jig.
The work system according to claim 1.
The storage unit stores, for each of the plurality of jigs, the degree of expected variation indicating the variation in the distance of the work object to be mounted from the reference mounting position.
When the work is performed on the defective jig, the control unit controls the work unit based on the actual deviation amount of the actual mounting position detected by the detection unit from the reference mounting position. For the defective jig, the expected variation degree is compared with the actual variation degree indicating the variation in the distance of the actual mounting position from the reference mounting position.
The working system according to claim 1 or 2.
The detection unit detects the actual mounting position of the work object mounted on one good jig arbitrarily selected from the at least one good jig.
The control unit compares the expected variation degree with the actual variation degree, which is the distance of the actual mounting position from the reference mounting position, with respect to the one good jig.
The work system according to claim 3.
In the control unit, the difference between the actual variation degree and the expected variation degree of the defective jig is larger than the first reference value, and the difference between the actual variation degree and the expected variation degree of the one good jig. When is equal to or less than the second reference value, the work in the defective jig is stopped.
The work system according to claim 4.
When the work is performed on the at least one good jig, the control unit controls the work unit based on the expected deviation amount.
The work system according to claim 5.
In the control unit, the difference between the actual variation degree and the expected variation degree of the defective jig is larger than the first reference value, and the difference between the actual variation degree and the expected variation degree of the one good jig. Is larger than the second reference value, and when the work is performed on each of the plurality of jigs, the work unit is controlled based on the deviation amount.
The work system according to claim 4.
In the control unit, the difference between the actual variation degree of the defective jig and the expected variation degree is equal to or less than the first reference value, and the actual variation degree and the expected variation degree of the one good jig When the difference is equal to or less than the second reference value and the work is performed on each of the plurality of jigs, the work unit is controlled based on the expected deviation amount.
The work system according to claim 4.