JPH09155546A - Welding tip change warning device of assembly line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the welding tip change warning device of assembly line capable of eliminating unnecessary tip change work and warning tip change work excellent in work efficiency and reliability. SOLUTION: A spotting number of each welding robot is monitored in a production control device 16 and life control of a welding tip is executed, further, a number of works between each process is grasped by tracking control with ID and a possible line stopping time is calculated. By comparing the line stopping time and a time required for tip change for each process, right/wrong of line stopping is discriminated and a process to execute tip change, further, stopping time of the welding robot/line are displayed by a terminal equipment 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembly which can efficiently and reliably warn the replacement of welding tips of a welding robot or an automatic welding machine installed in each work step of an assembly line. A welding tip replacement warning device for a line.

[0002]

2. Description of the Related Art For example, a body assembly factory is equipped with a large number of welding means (welding robots, automatic welding machines, etc.), and the body is mainly assembled by spot welding. The welding means for performing spot welding has a welding tip (hereinafter, also simply referred to as a tip) that serves as an electrode. Generally, a welding tip has a service life according to welding conditions, and the service life tip needs to be replaced to ensure welding accuracy. In the past, such welding tips were replaced all at once during the shift, or the tips were checked one by one using the line stop time, and as a result of the check, the state of the tips may deteriorate. For example, the tip is replaced.

[0003]

However, in such a conventional tip exchanging method, in the former case, since the tips of all the welding means are changed all at once, they are changed in terms of life. Even a welding tip that does not need to be replaced may include useless work. In the latter case, the replacement time is not clear and it is necessary to determine the time while checking the operating status of the line. In addition, it is necessary to check all of them, which causes a problem in work efficiency. However, the judgment of replacement is a visual check, which is a so-called guess, so there is a problem in terms of reliability.

The present invention has been made by paying attention to the above problems in exchanging the tips of the welding means installed in each process in the assembly line. The wasteful tip exchanging work is eliminated and the work efficiency and reliability are excellent. Another object of the present invention is to provide a welding tip replacement warning device for an assembly line, which can warn the operator of tip replacement work.

[0005]

In order to achieve the above object, the present invention according to claim 1 is an assembly line in which a plurality of work steps including welding means having welding tips are connected by a conveying means. A welding tip replacement warning device, which monitors the number of welding points of the welding tip, compares the number of welding points up to the present time with preset replacement timing data, and extracts a welding tip that has entered the replacement timing. With the preset replacement work time data,
First calculating means for calculating the time required for exchanging the welding tips extracted by the extracting means for each operation step,
Lines for each work process can be stopped based on detection means for detecting the number of works seated in the transport means located between each work process and data on the number of work seats between each work process detected by the detection means. Second calculating means for calculating time,
A deciding means for deciding a work process for terminating the line by comparing the replacement work required time calculated by the first calculating means with the line stoppable time calculated by the second calculating means, and the deciding means. Output means for issuing a warning of welding tip replacement to the performed work process.

In the present invention having such a configuration,
The extracting means monitors the number of welding points of the welding tip of each welding means, compares the number of welding points up to the present time with preset exchange time data, extracts the welding tip having entered the exchange time, and first calculating means. Calculates the time required for the replacement work of the welding tip extracted by the extracting means for each work process based on the preset replacement work time data.
On the other hand, the detecting means detects the number of works present in the conveying means located between the respective work processes, and the second calculating means uses the work presence number data between the respective work processes detected by the detecting means. , Calculate the line stoppable time of each work process. Then, the determining unit compares the required replacement work time calculated by the first calculating unit with the line stoppable time calculated by the second calculating unit, and determines a work process for stopping the line. The output means issues a warning of welding tip replacement to the work process determined by the determination means.

According to a second aspect of the present invention, in the above-mentioned first aspect, the second calculating means calculates the line stoppable time only for the work process which is the advancing process.

The basic principle of the present invention will be described with reference to FIG. As shown in the figure, for example, in the assembly line following the process A, the process B, the process C, ..., The line stoppable condition of the process B is basically the conveyance means a and b positioned before and after the process B. It is determined by the number of works (work presence). That is, the transport means a, b
The current number of workpieces present in the machine is Na, Nb, and the number of workpieces present in the conveying means a, b when the process B is in the equilibrium state is NA, Nb.
B, the maximum number of workpieces that can be transported by the transporting means a and b is NAmax, NBmax, and the number of workpieces at the delay limit of the transporting means a and b is NAmin and NBmin (FIGS. 1A and 1B). ), For example, firstly, if Na and NA are approximately equal and Nb and NB are approximately equal (where Na = NA and N
Abbreviated as b = NB. ) That is, when the process B is in an equilibrium state, it is desirable to maintain the current state of the process B without stopping the line, because the number of workpieces before and after the process B is appropriate. Second, when Na is larger than NA to some extent and Nb is smaller than NB to some extent (abbreviated as Na> NA and Nb <NB).
As for the process B, since the process B is a delayed process, it is preferable to stop the line as little as possible. Thirdly, when Na is smaller than NA to some extent and Nb is larger than NB to some extent (this is abbreviated as Na <NA and Nb> NB), the step B is the advanced step. Even if it is stopped, it does not affect other processes so much, and the line can be stopped in principle.

Therefore, in the invention according to claim 1, the maximum number of seats of the transporting means 1 is set as will be described later in order to give a unified common criterion while considering the above three cases. By calculating the line stoptable time of the process B in consideration of NAmax and the delay limit seating number NBmin of the conveying means 2 and comparing the obtained line stoppable time with the welding tip replacement work time in the process B, For the process B, it is determined whether or not the line can be stopped for chip replacement.

According to the second aspect of the present invention, the line stop possible time is calculated only in the third case (in which the process B is the advanced process) in which the line stop can be performed by further narrowing down the conditions. , The time required to replace the welding tip is compared. That is, in the first case (when the process B is in the equilibrium state) and the second case (when the process B is a delayed process) in which the line stop is not preferable, the line should not be stopped for chip replacement. There is.

According to a third aspect of the present invention, in the above-mentioned first or second aspect, the detecting means is an ID storing means which is attached to the work and stores an ID code of the work, and an entrance and an exit of each work process. Which are respectively arranged in
ID reading means for reading the ID code of the work from the D storage means, and I read by the ID reading means
The present invention is characterized by including a tracking means for tracking the location area of the work by the D code, and a counting means for counting the number of work seats in the area between the respective work processes based on the result of the tracking means. That is, the location of the work is managed using the ID assigned to each work, and the number of seats is detected based on this.

The invention according to claim 4 is the above-mentioned claim 1,
2 or 3, the output means displays a work process for stopping the line, a line stop time, and a welding means for replacing the welding tip.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing a general structure of a vehicle body assembly line. As shown in the figure, the body assembly line is roughly divided into four assembly processes (work processes), that is, an engine compartment process 1 for assembling an engine compartment, a front floor, a rear floor & members, and a body assembly line. The floor main process 2 to assemble the base floor, and the body side and roof etc.
Body main process 3 to make the skeleton of the body, and metal line process 4 to attach doors and hoods to the main body
It consists of In order to carry the work between the respective processes, the respective processes are connected by a carrying means (for example, an overhead conveyor). That is, an overhead conveyor 5 is provided between the engine compartment process 1 and the floor main process 2, an overhead conveyor 6 is provided between the floor main process 2 and the body main process 3, and an overhead conveyor is provided between the body main process 3 and the metal line process 4. Each conveyor 7 is installed.

FIG. 3 is a schematic diagram showing an embodiment of a welding tip replacement warning device of the present invention. In each assembling process (engine compartment process 1, floor main process 2, body main process 3, metal line process 4), as a welding means, for example, a welding robot group 8, 9, 10, 11 composed of a predetermined appropriate number of units. Are installed respectively. Each welding robot in each welding robot group 8-11 corresponds to the corresponding robot controller group 12, 13, 14, 15
It is controlled by a dedicated robot controller inside.
Each of the robot controller groups 12 to 15 is connected to a production management device 16 that manages a process in the vehicle body assembly line. The production management device 16 is composed of, for example, a computer and has a function (monitoring function) of monitoring the number of welding times of each welding robot. Therefore, the data of the number of welding points of each welding robot is given from the robot controller to the production management device 16. With such a monitoring function, the life of the tip of each welding robot is managed.

Further, the production control device 16 has a function (tracking function) of tracking (tracking) the location of the work flowing through the line. This tracking function is performed using the ID system. That is, for example, an ID plate (ID storage means) (not shown) storing the ID code of the work is attached to the work and allowed to flow in the line, and antennas # 1 to # 8 are installed at the inlet and the outlet of each of the assembling steps 1 to 4, respectively. The ID code is read by 17 (ID reading means). The ID code read by each antenna 17 is sent to the antenna 1 via the ID controller 18.
It is sent to the production control device 16 together with the number (#) of 7. The unique information of the work (manufacturing number, specifications, etc.) is stored in a predetermined area of the memory in the production management device 16 using the ID code as a key.

The work tracking result is, for example,
The file structure as shown in FIG. 4 is stored in a predetermined area of the memory in the production control device 16. That is, as shown in FIG. 3, seven zones are set as the work location areas,
A number is assigned to each zone, and the ID code of the work present in each zone is stored in association with the number of the present zone. If the work moves and the location area changes, the ID code movement processing is performed. The number of works present in each zone (the number of works present) is obtained by counting the number of ID codes included in each zone. The specific operation of tracking management will be described later in detail.

The production control device 16 includes an extraction means, a first calculation means, a tracking means (detection means), a counting means (detection means),
On the other hand, the welding robot that functions as the second calculating unit and the determining unit, and on the other hand, extracts the welding robot that needs the tip replacement by the above monitoring function, and calculates the time required for the tip replacement work in each assembly process, On the other hand, by the above tracking function, the number of seats on the overhead conveyors 5 to 7 (zones 2, 4, and 6) between the assembly steps is grasped, and the line stoppable time of each assembly step 1 to 4 is calculated. . Then, in each of the assembling steps 1 to 4, the line stoppable time is compared with the chip exchanging work required time to determine whether the line can be stopped for chip exchanging.

More specifically, whether or not the line can be stopped in each of the assembling steps 1 to 4 is determined as follows. In the case of the engine compartment process 1, the line stoppable time is calculated from the number of work seats on the overhead conveyor 5 and the delay limit seating count (see FIG. 1; the same applies hereinafter). That is,
Time T required for the number of work seats on the overhead conveyor 5 to decrease from the current value Nr to the delay limit seat count Nrmin when the engine compartment process 1 is stopped
r is calculated (see FIG. 5B), and the calculated time Tr is set as the line stoppable time of the engine compartment process 1. Then, assuming that the time required for the tip replacement work in the process is Tc (the same applies to the following), it is determined that the engine compartment process 1 can stop the line when the following formula Tr> Tc is satisfied.

In the case of the floor main process 2, the number of work seats and the maximum number of seats on the overhead conveyor 5 (see FIG. 1; the same applies hereinafter) and the number of work seats on the overhead conveyor 6 and the delay limit seating number are used to determine the lines. The stoptable time is calculated, and in the case of the body main process 3, the line stoptable time is calculated from the number of work seats on the overhead conveyor 6 and the maximum number of seats, and the number of work seats on the overhead conveyor 7 and the delay limit seating count. calculate. That is, when the assembly process 2 (3) is stopped, the time Tf required for the number of work seats on the overhead conveyor 5 (6) before the process to increase from the current value Nf to the maximum seat number Nfmax (see FIG. 5 (A)) and the time Tr required for the number of work seats on the overhead conveyor 6 (7) after the process to decrease from the current value Nr to the delay limit seat count Nrmin.
(See FIG. 5B), and these times Tf and Tr are calculated.
Is the line stop possible time of the floor main process 2 (body main process 3). Then, when the following expressions (Tf> Tc) and (Tr> Tc) are satisfied, it is determined that the floor main process 2 (body main process 3) can stop the line.

In the case of the metal line process 4, the line stoptable time is calculated from the number of seats on the overhead conveyor 7 and the maximum number of seats. That is, when the metal line process 4 is stopped, the time Tf (see FIG. 5 (A)) required to increase the number of seated work on the overhead conveyor 7 from the current value Nf to the maximum seated number Nfmax is obtained and calculated. The time Tf is set as the line stop time of the metal line process 4. Then, when the following expression Tf> Tc is satisfied, it is determined that the metal line process 4 can stop the line.

A terminal device 19 as output means is connected to the production control device 16. When the production control device 16 determines the assembly process for stopping the line for chip replacement, the terminal device 19 issues a chip replacement warning. Here, the terminal device 19 displays, as the content of the warning, an assembly process for stopping the line, a line stop time, and a welding robot that replaces the welding tip on the screen.
The line stop time is set to, for example, the calculated time Tc required for the tip replacement work in the process.

Next, the operation of the present apparatus configured as described above will be described using a flow chart. FIG. 6 is a flowchart of tracking management. Production control device 16
When the ID code is read by one of the antennas 17 (step S1), the antenna 17 that has received the ID code from the input signal from the ID controller 18
Number (#) and its ID code are extracted (step S
2), the antenna number (#) is determined (step S3,
Step S4).

If the antenna number (#) is 1, it means that the work has entered the engine compartment process 1, so that the ID code is newly added to the storage area of the zone 1 of the memory in the production control device 16. (Step S
5) If the antenna number (#) is 2 to 7, the work location area will change due to the movement of the work. Therefore, the zone (# -1) to the zone # of the memory in the production control device 16 are changed. When the ID code is moved to the storage area (step S6) and the antenna number (#) is 8, it means that the work has been carried out from the metal line process 4, so the zone of the memory in the production control device 16 The ID code is deleted from the storage area 7 (step S
7) (see FIG. 4 above).

After that, by counting the number of ID codes stored in each zone by this file, the number of works (the number of works) present in each assembling process, that is, in each overhead conveyor 5-7. Is counted (step S8). As described above, this counting result is used to determine whether the line can be stopped in each of the assembling steps 1 to 4.

The above series of processes is repeated until the end signal is input (step S9) when the entire assembly line is stopped.

FIG. 7 is a flowchart of the chip replacement warning process.

The production control device 16 inputs the data of the number of welding points of the corresponding welding robot from each robot controller in each robot controller group 12 to 15,
The number of hit points of each welding robot is monitored (step S11), and the welding robot that has entered the tip replacement time is selected (step S12). Whether or not the chip replacement time has come is determined by comparing the number of hit points up to the present time with preset chip replacement time data.
Since the welding condition differs depending on the welding location and therefore the life of the tip also varies depending on the welding location, the tip replacement timing should be set appropriately in advance according to the welding location by experiments.

Thereafter, for the welding robot extracted in step S12, the time required for the tip replacement work is calculated for each assembly process (step S13). Here, since the tip replacement work is performed simultaneously in units of each assembly process, the work time required for each welding robot for chip replacement required in each assembly process is added to calculate the time required for the entire assembly process. . The data of the work time required for the tip exchange of each welding robot is set appropriately in advance in consideration of, for example, the type of the welding robot and the installation location.

Then, in the next step S14, a correspondence table is created between the welding robot extracted in step S12 and the time required for the chip replacement work for each assembly process calculated in step S13. Stored in a predetermined area of.

Then, the result of tracking management (see FIG. 6)
Step S8) of each of the assembling steps 1 to 4 as described in detail above from the data of the number of seats of the overhead conveyors 5 to 7 (zones 2, 4, 6) between the assembling steps. Of the line stoptable time Tf and / or Tr is calculated (step S15), and the line stoppable time obtained in step S15 is compared with the chip replacement work required time obtained in step S13 for each of the assembling steps 1 to 4. Then, it is determined whether or not the line can be stopped for chip replacement based on the above-mentioned criteria (step S16).

YES as a result of the determination in step S16
If so, that is, if there is an assembly process capable of stopping the line, the chip replacement is performed in the assembly process (if there are a plurality, one selected according to a predetermined appropriate standard) by referring to the correspondence table created in step S14. A welding robot to carry out is determined (step S17), and a warning of tip replacement is issued through the terminal device 19 (step S18). The tip replacement warning is given by displaying on the screen the assembly process that stops the line, the line stop time, and the welding robot that performs the tip replacement. Note that step S16
If the result of the determination is NO, that is, if there is no assembly process capable of stopping the line, immediately step S19.
Proceed to.

Then, until the end signal is input when the entire assembly line is stopped (step S1)
9), the above series of processing is repeated.

Therefore, according to the present embodiment, the welding robot life is controlled by monitoring the number of welding points of the welding robot, and the tip replacement warning is issued only for the welding robot that has entered the tip replacement period. Further, it is possible to eliminate useless tip exchange work, and reduce work time and cost. Further, since the tip replacement is objectively judged based on the life management, reliability is also improved.

Further, the work is tracked and managed by the ID, and the result is used to judge whether the line can be stopped or not, and the assembly process for chip replacement is automatically selected. It is not necessary for each person to make a judgment by looking at the operating status of the line one by one, which improves work efficiency.

In the present embodiment, the welding robot has been described as an example of the welding means, but the welding means is not limited to this. For example, an automatic welding machine other than the welding robot may be used, or a system in which the welding robot and the automatic welding machine are mixed may be used.

Further, in this embodiment, four work steps are performed.
Although the description has been made by taking one vehicle body assembly process as an example, it goes without saying that the present invention is not limited to this.

Further, in the present embodiment, whether or not the line can be stopped in the assembling process is determined by simply comparing the time when the line can be stopped with the time required for the chip replacement work, but the present invention is not limited to this. Do not mean. For example, it is possible to make the above determination only in the case of the advanced process.

[0038]

As described above, according to the first aspect of the present invention, the life of the welding tips is controlled by the monitoring function, and the tip replacement warning is issued only for the welding tips that have reached the replacement time. It is possible not only to eliminate the need for chip replacement work, to reduce the working time and cost, but also to improve the reliability because the chip replacement can be objectively judged based on the life management. In addition, the line stop possible time is calculated by the number of seats in each work process, and the time required for the chip replacement work is compared to determine whether the line can be stopped or not. Since the selection is done automatically, it is not necessary for the workers on site to judge by looking at the operating status of the line one by one, thus improving work efficiency.

According to the second aspect of the present invention, in addition to the effect of the first aspect of the invention, since the line stoppable time is calculated only for the work process which is the advancing process, the chip is stopped when the line stop is not preferable. The line will not be stopped for replacement.

According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, it is possible to easily perform tracking management of the work by using the existing ID system.

According to the invention described in claim 4, claim 1,
In addition to the effects of the invention described in 2 or 3, not only the step of performing tip replacement and the welding means but also the line stop time are presented, so it is not necessary to see the line status.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the basic principle of the present invention.

FIG. 2 is a diagram showing a general configuration of a vehicle body assembly line.

FIG. 3 is a schematic configuration diagram showing an embodiment of a welding tip replacement warning device of the present invention.

FIG. 4 is an image diagram showing the structure of a tracking file.

FIG. 5 is a diagram used to explain criteria for determining whether or not a line can be stopped in each process.

FIG. 6 Flowchart of tracking management

FIG. 7 is a flowchart of a tip replacement warning process.

[Explanation of symbols]

1, 2, 3, 4 ... Assembly process (working process) 5, 6, 7 ... Overhead conveyor (conveying means) 8, 9, 10, 11 ... Welding robot group 12, 13, 14, 15 ... Robot controller group 16 ... Production management device (extracting means, first calculating means, tracking means, counting means, second calculating means, determining means) 17 ... Antenna (ID reading means) 18 ... ID controller 19 ... Terminal device (output means)

Claims (4)

[Claims] 1. A replacement warning device for the welding tip in an assembly line, in which a plurality of work steps including welding means having a welding tip are connected by a conveying means, the number of welding points of the welding tip is monitored, Compare the number of hit points up to now with the preset replacement time data,
Extraction means for extracting a welding tip that has entered the replacement period and first calculation means for calculating the required replacement operation time of the welding tip extracted by the extraction means for each work process based on preset replacement work time data And a detection means for detecting the number of works present in the transport means located between the work steps, and the work attendance line data between the work steps detected by the detection means, the line of each work step is detected. Second calculation means for calculating a stoppable time, and a work step for stopping the line by comparing the replacement work required time calculated by the first calculation means with the line stoppable time calculated by the second calculation means And a outputting means for issuing a warning of welding tip replacement for the work process determined by the determining means. Welding tip replacement warning device assembly line. 2. The welding tip replacement warning device for an assembly line according to claim 1, wherein the second calculation means calculates the line stoppable time only for a work process which is a leading process. 3. The detection means is an ID storage means that is attached to a work and stores a work ID code, and an ID reading unit that is arranged at the entrance and the exit of each work process to read the work ID code from the ID storage means. Means and
And a tracking means for tracking the location area of the work by the ID code read by the ID reading means, and a counting means for counting the number of the work seats in the area between the respective work processes based on the result of the tracking means. Claim 1 characterized by
Alternatively, the welding tip replacement warning device of the assembly line described in 2. 4. The output means displays a work process for stopping the line, a line stop time, and a welding means for exchanging welding tips.
Or the welding tip replacement warning device of the assembly line described in 3.