JPS6233068A - Control device for welding robot - Google Patents

Abstract

PURPOSE:To improve the welding operability, etc., by storing a data for indicating a correspondence relation of a welding current and a welding voltage, also deriving each command value to a current and a voltage of a designated welding, from the stored data, and controlling a welder. CONSTITUTION:A microcomputer 11 provided with a CPU 12 and a memory 13 is provided on a control device 10, and also it is connected to a welder 5 through D/A converters 4a, 4b. First of all, a mode changeover switch SW is set to a characteristic data generating mode, and a reference characteristic data by a test piece, etc. related to a welding current I and a welding voltage V is stored in the memory 13. Subsequently, by retrieving this reference characteristic data, command values SI, SV of the corresponding welding current and voltage are derived, respectively, and outputted to the welding machine 5. Also, the command values SI, SV are corrected and varied through a current sensor 19 and a voltage sensor 22. In this way, the operability of welding is improved, and it can be executed quickly to cope with a characteristic variation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a control method for welding current and welding voltage in a control device for a welding robot.

(Conventional technology and its problems) When welding workpieces using a welding robot, it is necessary to appropriately select the welding current and welding voltage depending on the type, posture, groove shape, etc. of the workpiece. . For this reason, a control device for a welding robot is usually configured to be able to select these welding currents and welding voltages.

The general configuration of such a control device is shown in FIG. In the figure, this control device 1 is a welding machine (welding power supply device)
5 and a servo system (not shown) of the welding robot.

This microcomputer 3 outputs a welding voltage command signal SV and a welding current command signal S1 according to welding conditions manually entered from the remote control panel 2 in a manner described later.
These are given to the welding machine 5 after being D/A converted by D/A converters 4a and 4b, respectively.

The welding machine 5 is configured to supply electric power to the torch 6 and the workpiece W according to these command values to provide a welding voltage V and a welding current I.

In the configuration shown in FIG. 7, there are two methods for specifying welding current and welding voltage from the keyboard 2 as follows. One is the desired welding current ■ and welding voltage ■
In this method, several to several dozen suitable combinations are prepared in advance, and a set of a welding current command (ias) and a welding voltage command value Sv corresponding to each is specified by a menu number.

In creating this menu, we need to determine the following: ■ Correspondence between welding N flow command value S■ and welding current I, and ■ Welding voltage command value S, as shown in FIG.

It is necessary to obtain in advance characteristic data (characteristic curves) that express the correspondence between the welding voltage and the welding voltage ■.

However, in this method, the command value S1. Since S is selected, the actual welding current I and welding voltage ■ cannot be directly specified, and it cannot be used in numerically controlled robots using CAD or CAM.
Since the number of menus is limited, there is a problem in that it is not always possible to specify optimal welding conditions.

On the other hand, in the second method, the characteristic data of the second and fourth quadrants of FIG. 8 are stored in a ROM in the microcomputer 3 of FIG. It is specified directly from 2. Then, welding current command value S1 and welding voltage command value SV corresponding to the designated welding current I and welding voltage V are determined from the characteristic data in the ROM and output to the welding machine 5. Therefore, in this case, control will be performed by combining the logical conversion of "actual value → command value" by the ROM and the conversion of "command value → actual value" in the actual welding machine 5. .

However, as is well known, the actual welding current I and welding voltage V are not uniquely determined by the command values from the control device, but are also determined by the characteristics of the welding machine itself, as well as the workpiece and torch during welding. It changes depending on the position of the body, the wire extension, and other factors. For this reason, the actual welding characteristics differ depending on the work object and work environment, and in the second method above, the RO
There is a problem that M must be replaced.

(Objective of the Invention) This invention is intended to overcome the above-mentioned problems, and allows the welding current and welding voltage to be directly specified to improve operational control and to respond accurately and quickly to changes in welding characteristics. The purpose is to provide a control device for a welding robot that can

(Means for Achieving the Object) In order to achieve the above-mentioned object, the welding robot control device according to the present invention detects welding current and welding voltage while causing the welding robot to perform welding. A characteristic data creation means is provided for creating characteristic data expressing the correspondence between the welding current command value and welding voltage command value given to the welding machine from the device and the actual welding current and welding voltage, and the characteristic data is converted into desired values. The welding current command value and the welding voltage command value corresponding to the specified welding current and welding voltage are stored as characteristic data in the storage means and are created at any time and stored in the storage means. It is then output to the welding machine.

(Embodiment) Overall configuration of the embodiment FIG. 1 is a block diagram of a control device for a welding robot which is an embodiment of the present invention. In the figure, this control device 10 has a microcomputer 11 including a CPU 12 and a memory 13, and this memory 13 includes a RAM 14 that stores characteristic data, which will be described later, in a readable and writable manner.

Moreover, the pass line BL of this microcomputer 11
A remote control panel 15 for input/output is connected to. The remote control panel 15 includes a mode changeover switch SM for switching modes such as manual mode, auto mode, and characteristic data creation mode, and a manual operation snap switch group SW for manually moving the torch 6. In addition, there is a start switch ST for instructing data acquisition and start of operation.
A, numeric keypad 16 for inputting various numerical values, and LE
A D display 17 and the like are provided.

Furthermore, a robot servo system 18 including a mechanical power M and an encoder E of the welding robot is connected to the pass line BL, and the microcomputer 11 provides a drive command output S8 to this system, and It is adapted to take in the encode signal SE. Note that the mechanical configuration of the welding robot, such as the servo system 18, can utilize the configuration of a conventional welding robot, so detailed explanation will be omitted.

On the other hand, the welding voltage command signal Sv and welding voltage command value @S1 from the microcomputer 11 are provided to the welding machine 5 after being converted into analog signals by D/A converters 4a and 4b, respectively. Welding power PW supplied from the welding machine 5 in response to these input signals is applied to the consumable electrode 20 via the current sensor 19. This consumable electrode 20 is wound around a spool 21, and one end thereof extends to the torch 6, and can be fed out by a feed roller (not shown).

Furthermore, the welding voltage ■ and the welding current I during actual welding are detected by the voltage sensor 22 and the current sensor 19 inserted between the consumable electrode 20 side and the work W side, respectively, and the voltmeter 23 is displayed on the ammeter 24, and the A/D converter 25a, 25b performs an A/D
The data is converted into D and taken into the microcomputer 11.

Next, among the operations of this control device, creation and storage of characteristic data will be explained with reference to FIG.

This operation is performed at a desired time, for example, before the start of a day's welding work, or whenever the task or work environment changes.

First, after operating the mode changeover switch SM in FIG. 1 to set the characteristic data creation mode, in step S1, welding current! For each of the welding voltage V and the welding voltage V, input one value from the numeric keypad 16 as a target value. Criteria for selecting these target values will be described later.

In the next step S2, the CPLJ12
3. Search the standard characteristic curve data stored in advance in 3, and check the input welding current value I and welding voltage V.
Welding is performed by determining a welding current command value S1 and a welding voltage command value Sv respectively corresponding to and outputting these to the welding machine 5. This "reference characteristic curve" data is characteristic data created in advance using a test piece or the like, and an example thereof is shown by C0 in FIG.

That is, in step S2, when the input welding current value is IA, the welding current command value SA is determined based on this reference characteristic curve C6, and this command value SA is output to the welding machine 5.

Although FIG. 3 only shows the welding current (2) and does not show the welding voltage V, the welding voltage V is also treated in the same way. In addition, although the description below will focus on current, it should be understood that the same process is performed for voltage as well.

In step S3, the CPU 12 takes in the detected values from the current sensor 19 and voltage sensor 22 in FIG. 1, and changes the commands ms, sv so that the welding current (2) and the welding voltage V each match the target values.

That is, the standard characteristic curve C8 in FIG. 3 is fixed data that has been prepared in advance, and when the welding conditions change, the command value S1. Even if Sv is output, the welding current/welding voltage value N11i cannot actually be obtained as is, so the command value is corrected to actually obtain the target value. for example,
The command l11 [SA was output for the target value ■ in Fig. 3, but the actual characteristic curve is C1, and when the current ■B is detected as the welding current ■, the command value is changed from SA to S.
By correcting it to 8, the target value IA is achieved.

When the state corresponding to the target value is achieved in this way,
In the next step S4, the command values S, S,
etc., are taken in by the CPU 12 and stored in the corresponding area in the RAM 14. Note that selection of a storage area when obtaining a plurality of types of characteristic data under different conditions will be described later.

In the next step S5, it is determined whether all target values have been input. If not, the process returns to step S1 and repeats the same operation. In other words, to find the characteristic curve,
It is necessary to sequentially input the target values of the credit unions and obtain (corrected) command values for them, but in this example, the number of sets is 10, and for example, as shown in Fig. 5, which will be explained later. , target values I , I , ..., 11o
be input in sequence. Then, the command value S corresponding to these
1°S2. ..., S10 is found and stored.

There is no particular limitation on how to determine this target value, but the characteristic curve is as shown in FIG. 3 or the above-mentioned FIG.
Since the center part is almost a straight line, and the end parts often have a large curvature, it is desirable to set them sparsely at the center and densely at the ends.

Returning to FIG. 3, when the data acquisition for all target values is completed, the process moves to step S5, and based on the acquired data, welding current I, welding voltage ■, and their respective correction command values are determined. New characteristic curve data is created based on the correspondence between them, and stored in the corresponding area in the RAM 14, completing the characteristic data creation and storage process.

However, when measuring characteristic data, the method is not limited to this method. For example, as shown in FIG.
The command value according to the standard characteristic curve for A is SA, and when this command value SA is actually given, IB is the welding current.
is detected, IA is corrected to ■, and this I,
The value may be stored as a corrected current value.

1211111% By the way, in this example, only 10 sets of values are used as target values, so it is not possible to directly obtain characteristic data for all welding current values ■ and welding voltage values V using only the raw data. isn't it. For example, if welding current value I and welding voltage value V can each be input in 8 bits (=256 levels), data regarding values other than the target values will be required during actual welding work.

Therefore, in this embodiment, by interpolating the data obtained for the target values, it is possible to input all welding currents I and welding voltages (2) in 8-bit representation.

This interpolation may be performed in step S6 of FIG. 3 above, and the data including this supplement am may be stored in the RAM 14, or only the 10 sets of measured values may be stored as the characteristic data. In addition, during actual welding work, interpolation calculations may be performed based on the data read out from the RAM 14, but this interpolation method will be explained here.

As shown in Figure 5, (S, I2), (82°12
), ·, (S , I ) (7) When 10 sets of note data are obtained, in this embodiment, linear interpolation is performed between two adjacent sets of data, and the maximum value S of the command value S is
1 between (-255) and 810
For the 18X interval and the 1n interval between the minimum value S ・(-〇) and $1, 59=810 reading and Sl, respectively.
Data is obtained by performing linear extrapolation using the data of S2. This is because linear interpolation is the simplest and requires less processing time, and also because most parts of the characteristic curve are originally linear, so linear interpolation results in a highly viscous approximation. expose. However, since the curvature may be relatively large near the end of the characteristic curve, it is also effective to employ circular interpolation or the like.

The broken line obtained in this way is shown as a broken line in FIG. 5, and it can be seen that the characteristic curve can be reproduced fairly faithfully by this interpolation.

c,, ri Once new characteristic data is obtained as described above during operation, actual welding work can be carried out. Next, this operation will be explained with reference to FIG. 6.

First, in step 810, the values of welding current ■ and welding voltage V for each welding section are specified in teaching data for the playback method, and in data prepared in advance for the numerical control method, and then the welding robot Set to play mode. Next step 81
1, the CPU 12 searches the characteristic data in the RAM 14 and issues commands 1as1.1 for the welding current l and welding voltage V in the first welding section. Read and set S. Note that when the above-mentioned interpolation is performed at the time of reading, the interpolation process is performed in this step to obtain the command value.

In the next step S12, these command values SI.

S, is output to the welding 115 to perform welding in that section. At this time, of course, the servo system 18 is also being controlled. Then, in step S13, it is determined whether or not all the welding sections have been welded. If there are welding sections remaining, the process returns to step S11 and the same process is repeated. , complete the process.

By the way, if one welding robot performs welding with only a single posture or a single groove shape, it is sufficient to create only one type of characteristic data. However, conditions such as posture may differ between sections,
Furthermore, when different types of workpieces must be alternately welded, it is desirable to use different characteristic curves for each section or type of workpiece.

In such a case, create the above-mentioned characteristic data separately for each condition, and store multiple characteristic data in RAM.
14 in different areas, and during welding work, the corresponding area can be accessed and necessary characteristic data can be retrieved for each condition.

Therefore, in this case, when creating the characteristic data, enter the conditions as parameters from the numeric keypad 16, and store in steps 84 and 86 in FIG. 2 and read in step 811 in FIG. The configuration is configured so that it is performed for the designated area. By doing so, characteristic data corresponding to each condition can be prepared and used, thereby further utilizing the advantages of the present invention.

1 star 3 By the way, this invention is not limited to the above embodiment, and for example, the following modifications are also possible.

■ In the above embodiment, the detection values of welding current ■ and welding voltage V are taken in and judged when creating the characteristic data as shown in Fig. 1 (7).
A/D: CPCI via l inverters 25a, 25b
2 is carried out, but if the operator is an expert, he or she can visually observe the actual welding arc condition and change the command value using a switch installed on a remote control panel, etc.
The detected value may be taken in by pressing the start switch STA or the like when it is determined that the state is stable. In this case, the A/D converters 258, 25b, etc. are unnecessary, and by doing so, it is possible to reduce the cost of the device.

■Target value setting for creating characteristic data does not have to be done manually; for example, target values can be set automatically in fixed value increments from predetermined 'R current/voltage values. It is also possible.

■In the above embodiment, interpolation processing is performed to shorten the data acquisition processing time for creating characteristic data, but when particularly high accuracy is required, all targets depending on the resolution It is also possible to take in data on values or command values to further refine the characteristic data.

■When creating characteristic data, new data is obtained by correcting the standard characteristic curve prepared in advance, but instead of the standard characteristic curve, the characteristic data previously created and stored in RAM is corrected. Alternatively, instead of correction, characteristic data may be created directly.

■If you want to create and save characteristic data for each of many types of conditions, use R in the microcomputer.
This is not limited to AM, but may be stored in an external storage device such as a cassette tape or bubble memory. In particular, when correcting the previously created characteristic data to obtain new characteristic data, as in (■) above, make sure that the characteristic data at that point does not disappear when the power is turned off when the work is completed. It is necessary and such a modification is effective.

(Effects of the Invention) As explained above, according to the present invention, operability is improved by directly specifying the welding current and the welding current, and the characteristic data can be updated with new ones as necessary. Therefore, it is possible to obtain a control device for a welding robot that can accurately and quickly respond to changes in welding characteristics.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a control device that is an embodiment of the present invention, Figs. 2 and 6 are flowcharts showing the operation of the embodiment, and Figs. 3 and 4 are the principle of creating characteristic data and its modifications. FIG. 5 is a diagram showing an example of interpolation, FIG. 7 is a block diagram showing the general configuration of a conventional device,
FIG. 8 is a diagram illustrating welding characteristics. 1.10... Control device 3.11... Microcomputer 2.15... Remote control panel, 5... Welding machine 6...
・Torch, W...Work Figure 5 Figure 6

Claims (3)

[Claims] (1) In a welding robot control device for causing the welding robot to perform a welding operation on a workpiece, the welding A characteristic data creation means is provided for creating characteristic data expressing the correspondence between the welding current command value and welding voltage command value given to the welding current and the actual welding current and welding voltage, respectively, and the characteristic data is generated at any desired time. It is created and stored in the storage means, and when performing welding work, the welding current command value and the welding voltage command value corresponding to the specified welding current and welding voltage are generated from the characteristic data in the storage means. A control device for a welding robot, characterized in that the control device calculates the output value and outputs it to the welding machine. (2) Control of the welding robot according to claim 1, wherein the characteristic data creation means is a means for creating new characteristic data by correcting other characteristic data given in advance. Device. (3) The characteristic data creation means is means for determining the correspondence relationship for a specified number of welding current values and welding voltage values, and creating new characteristic data based on the correspondence relationship, and the control device 3. The welding robot control device according to claim 2, further comprising an interpolation means for interpolating the characteristic data.