JP3572773B2 - Energization control system for multiple welding machines - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an energization control system for a plurality of welding machines that integrally controls welding timings of the plurality of welding machines by controlling a plurality of switches with one welding timer.
[0002]
[Prior art]
For example, when a plurality of welding machines (for example, welding robots) are arranged on one stage to weld an object to be welded in the stage, conventionally, as shown in FIG. 8, each robot 1 (# 1 to # 4) ), A set of welding timers 2 and contactors (switches) 3 were individually connected.
[0003]
The primary circuit of each robot 1 contains a contactor 3 of a welding power supply (main power supply). While the contactor 3 is closed, a main current is supplied from the same power supply to the welding transformer via the lead-in wire 4, A welding current flows through the secondary circuit. ON / OFF of the welding current, that is, control of the energization time (including control of energization start) is performed by controlling the contactor 3 according to a command from the timer 2. Note that, in the figure, reference numeral "5" is a robot controller.
[0004]
[Problems to be solved by the invention]
However, in such a conventional energization control system, it is necessary to provide one set of the welding timer 2 and the contactor 3 for one welding machine 1, so that not only is the equipment itself costly, but also the equipment is expensive. It takes man-hours and costs to maintain the equipment. In other words, an increase in equipment-related costs is inevitable.
[0005]
Further, in the above-described conventional power supply control system, since each welding machine 1 performs welding independently without mutual connection, there is a possibility of simultaneous power supply depending on the timing of a welding request. When a plurality of welding machines 1 are energized at the same time, the power supply voltage decreases, the current becomes insufficient, and the welding quality may deteriorate.
[0006]
In order to avoid this problem, the welding timing should be shifted. However, the adjustment requires a review of the welding program (for example, a robot program) (re-doing the teaching). Become.
[0007]
The present invention has been made by paying attention to the above-described problem in energization control in a welding system including a plurality of welding machines, and aims to reduce equipment-related costs and always ensure a constant welding quality. It is an object of the present invention to provide a power supply control system.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is provided in each of the plurality of welding machines in a current control system for controlling a plurality of welding machines connected to the same power supply. The current switching means and the energization requests from the plurality of welding machines are input and the welding timing of each welding machine is intensively monitored.If there are a plurality of energization requests, the corresponding plurality of welding machines are energized simultaneously. Even if the fluctuation of the power supply voltage falls within a predetermined allowable range, and if it falls within the allowable range, the current switching means is controlled so that the corresponding plurality of welding machines are simultaneously energized, In a case where the current does not fall within the allowable range, a common control unit that controls the current switching unit so that the energization timings of the plurality of welding machines correspond to each other is provided.
[0011]
According to the present invention, a single control unit inputs energization requests from a plurality of welding machines and intensively monitors the welding timing of each welding machine. Controls the current switching means of the machine. That is, the welding timing of a plurality of welding machines is adjusted by one control means. The control means adjusts the welding timing of the plurality of welding machines. As a result, each welding machine performs welding while cooperating with each other, such as shifting the welding timing. In particular, the control means determines whether or not the fluctuation of the power supply voltage when a plurality of welding machines corresponding to the energization request are energized at the same time is within a predetermined allowable range. Prevent fluctuation of power supply voltage from exceeding an allowable range.
[0012]
According to a second aspect of the present invention, in the power supply control system for a plurality of welding machines according to the first aspect , the power supply system further includes a voltage measuring unit for measuring a power supply voltage, wherein the control unit detects an abnormality in the power supply voltage by the voltage measuring unit. The current supply is stopped when is detected.
[0013]
According to a third aspect of the present invention, there is provided the power supply control system for a plurality of welding machines according to the second aspect , further comprising an alarm unit that outputs an alarm when the abnormality of the power supply voltage does not recover within a set time. .
[0014]
According to a fourth aspect of the present invention, in the current supply control system for a plurality of welding machines according to the first to third aspects, the control means determines whether or not the fluctuation of the power supply voltage falls within the allowable range. When the power supply voltage is within a range from a predetermined lower limit to an upper limit, or when the number of the welding machines that are simultaneously energized is equal to or less than a predetermined number, it is determined that the power supply voltage falls within the allowable range. I do.
[0017]
【The invention's effect】
According to the first aspect of the invention, since adjusting the welding timings of a plurality of welding machines by a single control unit, with reduction by reducing the capital costs associated number is achieved in the control unit, the power supply voltage too low Therefore, constant welding quality is always ensured.
[0018]
According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, when the abnormality of the power supply voltage is detected, the energization is stopped, so that the welding current can be stabilized also from this point. A certain welding quality is ensured.
[0019]
According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, an alarm is output when the abnormality of the power supply voltage does not recover within the set time, so that the operator can easily recognize the abnormality of the power supply. You can know.
[0020]
According to the invention described in claim 5, the control means, when the power supply voltage is within a range from a predetermined lower limit to an upper limit, or when the number of the welding machines to be energized simultaneously is less than or equal to a predetermined number, Since it is determined that the current falls within the allowable range, the energization timing is shifted in other cases. Therefore, the power supply voltage is not excessively reduced, and a constant welding quality is always ensured.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a power supply control system for a plurality of welding machines according to an embodiment of the present invention. Note that the same parts as those in FIG. 8 are denoted by the same reference numerals.
A plurality (four in this example) of welding robots 1 (hereinafter, simply referred to as robots) are arranged on the welding stage as welding machines. The workpiece in the stage is welded by these four robots 1 (# 1 to # 4).
[0022]
Each robot 1 is provided with a welding gun, a welding transformer, and the like (not shown). The primary side of the welding transformer of each robot 1 has a common welding power source (main power source) via a contactor 3, a welding electric trunk 6, and a drop-in wire 4. ) And connected. A contactor 3 connected to the primary side of the welding transformer of each robot 1 is a switch of a main power supply and functions as a current switch. While the contactor 3 is closed, the main current is supplied from the power supply to the welding transformer, and the welding current flows through the secondary circuit. The contactor 3 includes one configured by using two thyristors and the like, and one configured by an inverter.
[0023]
The contactors 3 of the robots 1 in the same stage are connected to a common centralized management timer 7. The centralized management timer 7 functions as a control means, and is obtained by integrating welding timers (see FIG. 8) provided separately for each contactor 3 in the related art. ON / OFF of the welding current in each robot 1, that is, control of the energization time (including control of energization start) is performed by controlling the contactor 3 of each robot 1 according to a command from the central management timer 7. . The centralized management timer 7 has a built-in microcomputer (microcomputer timer), as described later, and has a function of uniformly controlling the energization time of each robot 1 and appropriately adjusting their welding timing.
[0024]
A monitor 8 is connected to each central control timer 7. The monitor 8 has a function of displaying on a screen the welding state of each robot 1 in the same stage under the control of the centralized management timer 7 to which the monitor 8 is connected, and has a function of issuing an alarm in a predetermined case as alarm means. . The alarm is issued, for example, when the abnormality of the power supply voltage continues beyond the set time.
[0025]
The welding electric trunk 6 is provided with a voltage measuring device 9 as voltage measuring means for measuring a mains voltage (power supply voltage). The voltage measuring device 9 is connected to each central control timer 7 via the information network 10, and the data of the power supply voltage measured by the voltage measuring device 9 is sent to each central control timer 7 and monitored there.
[0026]
A robot controller 5 is connected to each of the robots 1, and the operation of the robot body is controlled by the robot controller 5. The robot controller 5 of each robot 1 is connected to a centralized management timer 7, which synchronizes the operation of the robot 1 with the welding timing. That is, upon receiving the power supply request from the robot controller 5, the centralized management timer 7 issues a power supply command to each contactor 3. The operation of each robot 1 including the welding timing has been previously taught. Here, the learned welding information (order of welding points, energizing time, etc.) is also stored in the central control timer 7 for each robot 1. In addition, the centralized management timer 7 teaches the priority of each welding part.
[0027]
FIG. 2 is a block diagram showing the configuration of the centralized management timer 7.
As shown in FIG. 1, the centralized management timer 7 includes an input processing unit 11 for inputting a signal from the outside, a memory 12 for storing an operation program of the centralized management timer 7 and various registration data, and data relating to an energization request. And a CPU 14 for performing various arithmetic processing described later, and an output processing unit 15 for performing processing for outputting processing results of the CPU 14 to the outside.
[0028]
The voltage measurement device 9 and the robot controller 5 of each robot 1 are connected to the input processing unit 11. The power supply voltage data measured by the voltage measuring device 9 and the energization request signal from the robot controller 5 are taken into the centralized management timer 7 via the input processing unit 11.
[0029]
The memory 12 is composed of, for example, a ROM, in which the operation program of the centralized management timer 7 and various registration data are stored in advance, as described above. The registration data includes, for example, an allowable range of power supply voltage (for example, an upper limit value and a lower limit value) that can guarantee quality, welding information using a robot # as a key (weld point order, energizing time, priority order, etc.), welding Reference data for timing adjustment (relationship between energization and power supply voltage drop) and the like.
[0030]
The energization request buffer 13 temporarily stores data relating to the energization request, as described above. When storing the energization requests, the energization requests are stored in the order in which the energization requests are received, and the energization is normally performed in this order. In particular, when a plurality of energization requests are received simultaneously or within a time interval set so as to be regarded as simultaneous, the respective energization requests are stored so as to be energized according to their welding priorities.
[0031]
The CPU 14 has a function of inputting a measured value of the voltage measuring device 9 to monitor the power supply voltage, a function of inputting an energization request from each robot controller 5 and centrally managing the welding timing of each robot 1, and the like. are doing. In centrally managing the welding timing of each robot 1, the energization timing is adjusted so that the fluctuation of the power supply voltage falls within a predetermined allowable range. As described above, the allowable range of the power supply voltage is defined by the upper limit and the lower limit. For example, when the reference value of the welding power source is 200 V, the upper limit is set to 220 V and the lower limit is set to 180 V. How to set the allowable range of the power supply voltage is a matter of operation, and may be appropriately set as long as welding quality can be ensured.
[0032]
The output processing unit 15 is connected to the contactor 3 of each robot 1 in addition to the monitor 8. The monitoring state (power supply voltage, welding timing, welding result) and an alarm (alarm) signal in the CPU 14 are output to the monitor 8 via the output processing unit 15. An energization command to the energizable robot 1 selected by the CPU 14 is also output to each contactor 3 via the output processing unit 15.
[0033]
Next, the operation of the present system configured as described above will be described with reference to the flowcharts of FIGS. FIG. 7 is referred to as appropriate. 7A and 7B are diagrams showing an example of the energization timing. FIG. 7A shows a case where the energization timing is not adjusted, and FIG. 7B shows a case where the energization timing is adjusted according to the present invention. .
[0034]
FIG. 3 is a main flowchart showing the operation of the central management timer 7.
The operation of the centralized management timer 7 is as shown in the figure. First, measurement data is taken in from the voltage measuring device 9 to monitor the mains voltage (step S1). Here, how the mains voltage fluctuates as time (t) elapses (see FIG. 7). Then, based on the monitoring result, it is determined whether the mains voltage is normal, that is, whether the mains voltage is within a range in which quality can be guaranteed (between a lower limit value of 180 V and an upper limit value of 220 V) (step S2), and NO is determined. If so, a predetermined abnormality process is performed (step S3), and the process returns to step S1. If YES, management of the energization request (step S4) and energization timing process (step S5) are performed until the welding operation is completed (step S6). )repeat. All of these processes are performed by multitasking.
[0035]
FIG. 4 is a flowchart showing the contents of the abnormality processing in FIG.
When the abnormality of the mains voltage is detected in step S2, more specifically, when the mains voltage abnormally rises and exceeds the upper limit value (220V) (see section a in FIG. 7B), or When the mains voltage drops abnormally and exceeds the lower limit value (180 V) (in the present invention, the voltage does not drop abnormally during energization, so it is limited to a case where it drops for some reason other than during energization). Is not in a power supply state in which quality can be guaranteed, so the system is immediately stopped to end all welding work (step S11). At this time, the reception of the energization request is also stopped. Thereafter, it is determined whether or not the set time has elapsed from the time when the abnormality of the mains voltage is detected (step S12). If YES, an alarm (alarm) for notifying the power supply abnormality is output from the monitor 8 (step S13). ) Return, if NO, return immediately. That is, when the mains voltage is restored and becomes normal within the set time, the power supply is resumed without issuing an alarm, and an alarm is output only when the mains voltage is not restored within the set time.
[0036]
FIG. 5 is a flowchart showing the contents of the energization request management process in FIG.
If it is determined in step S2 that the mains voltage is normal, the energization request can be received (step S21), and it is determined whether or not an energization request has been received from the robot controller 5 (step S22). If YES, the following series of processing is performed.
[0037]
That is, when there is an energization request, the number (#) of the robot 1 that has issued the energization request is acquired (step S23), and the registered welding data in the memory 12 is accessed by using the robot # as a key to obtain the number. The energization time is grasped (step S24), and the result is stored and accumulated in the energization request buffer 13 together with the robot # (step S25). As described above, the energization requests are stored in the buffer 13 in such a manner that the energization requests are stored in the order in which the energization requests are received, and within a time interval set so that a plurality of energization requests are considered simultaneously or simultaneously. If accepted, they are stored according to the priority order.
[0038]
FIG. 6 is a flowchart showing the contents of the energization timing process in FIG.
As described above, this processing is executed by the multitask in parallel with the energization request management processing in step S4 and the power supply voltage monitoring processing in steps S1 to S3. Here, first, it is determined whether or not there is power supply request data in the power supply request buffer 13 (step S31). If NO, the process immediately returns and waits, and if YES, the next series of processes is performed.
[0039]
That is, the robot 1 at the head of the energization request buffer 14 is selected (step S32), and it is first determined whether or not the other robot 1 is currently energized (step S33). Therefore, the process immediately proceeds to step S35 to output an energization command to the contactor 3 of the robot 1.
[0040]
On the other hand, if the result of determination in step S33 is YES, simultaneous energization is performed, so it is determined whether simultaneous energization in this case is possible from the viewpoint of quality assurance (step S34). This determination is made by looking up the registered reference data (the relationship between the energization and the drop in the power supply voltage) in the memory 12 and energizing the robot 1 so that the power supply voltage falls below the lower limit (180 V) which is an allowable range. It depends on whether there is a possibility. It should be noted that in this determination, it is also possible to simply regulate by the number of simultaneous energization, instead of regulating by the degree of voltage drop as in the present invention. Further, it is also possible to regulate the degree of the voltage drop and the number of simultaneously energized devices.
[0041]
If the result of the determination in step S34 is NO, the quality may not be ensured due to the simultaneous energization. Therefore, the process returns to step S33 to delay the energization of the robot 1 and shift the timing. For example, as shown in FIG. 7A, in section b, the energization to four robots 1 (# 1 to # 4) is concentrated, and the power supply voltage falls below the lower limit (180 V). By delaying the energization timing of the robot # 4 as in the present invention, the fluctuation of the power supply voltage can be suppressed within an allowable range.
[0042]
If the result of determination in step S34 is YES, since simultaneous energization does not affect the quality, an energization command is output to the contactor 3 of the robot 1 (step S35). The contactor 3 is closed while receiving the command, whereby the main current is supplied from the power supply to the welding transformer, the welding current flows to the secondary side, and the welding is actually performed.
[0043]
The energization command from the centralized management timer 7 to the contactor 3 is continuously output until the energization time at the welding point ends, and stops when the energization time elapses, and the energization ends (steps S36 and S37).
[0044]
When the energization is completed, the energization request data in the energization request buffer 13 is deleted (step S38), and the process returns.
[0045]
Therefore, according to the present embodiment, the welding timer provided separately for each contactor 3 in the past is integrated and the centralized timer 7 is used to centrally manage the welding timing of each robot 1. And equipment costs are reduced, and the man-hours and costs for equipment maintenance are also reduced.
[0046]
Further, when the welding timing of each robot 1 is centrally managed by the central control timer 7, the welding timing of each robot 1 is adjusted so that the fluctuation of the power supply voltage falls within the allowable range (180 V to 220 V). In addition, the power supply voltage does not excessively decrease due to the simultaneous energization, and a constant welding quality is always ensured.
[0047]
As a result, it is not necessary to review the program (re-teaching) for the purpose of adjusting the welding timing, and the review work of the program can be minimized, so that such work is greatly reduced.
[0048]
In addition, since the welding timing is automatically adjusted to always maintain a constant welding quality, it is not necessary to easily increase the trunk line capacity even when the number of welding machines increases, and there is also a cost advantage from this point. .
[0049]
In the present embodiment, the welding robot 1 has been described as an example of a welding machine, but it is a matter of course that the present invention is not limited to this.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an energization control system for a plurality of welding machines according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of a centralized management timer. FIG. 4 is a flowchart showing the contents of the abnormality processing in FIG. 3; FIG. 5 is a flowchart showing the contents of the power supply request management processing in FIG. 3; FIG. 6 is a flowchart showing the contents of the power supply timing processing in FIG. FIG. 8 shows an example of energization timing. FIG. 8 shows a conventional example.
1 ... Welding robot (welding machine)
3. Contactor (current switch, current switch, switch)
4: Lead-in wire 5: Robot controller 6: Electric trunk line 7 for welding 7: Centralized management timer (welding timer, control means)
8 Monitor (alarm means)
9 Voltage measuring device (voltage measuring means)
10. Information Network

Claims (4)

In a power supply control system for a plurality of welding machines that controls power supply to a plurality of welding machines connected to the same power supply,
Current switching means provided for each of the plurality of welding machines,
Input of energization requests from the plurality of welding machines to intensively monitor the welding timing of each welding machine, and when there are a plurality of energization requests, fluctuations in the power supply voltage even if the corresponding plurality of welding machines are energized simultaneously. Is determined to be within a predetermined allowable range, and if it is within the allowable range, the current switching means is controlled so that the plurality of corresponding welding machines are energized simultaneously, and the current does not fall within the allowable range. In the case, common control means for controlling the current switching means so that the energization timing of the corresponding plurality of welding machines is shifted ,
A power supply control system for a plurality of welding machines, comprising: 2. The current supply control of a plurality of welding machines according to claim 1 , further comprising voltage measurement means for measuring a power supply voltage, wherein the control means stops the current supply when the voltage measurement means detects an abnormality in the power supply voltage. system. 3. The current supply control system for a plurality of welding machines according to claim 2, further comprising an alarm unit that outputs an alarm when the abnormality of the power supply voltage is not recovered within a set time . The control means, when judging whether the fluctuation of the power supply voltage falls within the allowable range, when the power supply voltage is within a range from a predetermined lower limit to an upper limit, or when the welding is performed simultaneously. The energization control system according to any one of claims 1 to 3, wherein it is determined that the number falls within the allowable range when the number of machines is equal to or less than a predetermined number.

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