JPH0369622B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a control device for a welding machine that is capable of obtaining an actual output value that matches an output value set in an output setting circuit.

<Prior art> Welding equipment is generally configured to set the output current value, voltage value, welding speed, etc., and then feedback the output value to the set value to form a closed loop to obtain the desired value. ing.

In the consumable electrode arc welding method using a power source with normal constant voltage characteristics, the electrode wire is fed at a substantially constant speed, and the welding current value is set because the welding current value is approximately proportional to this wire feeding speed. Specify the wire feed speed as a signal. By keeping this wire feeding speed at the set value, a welding current value that satisfies "wire feeding amount=wire melting amount" flows.

<Problem to be solved by the invention> In this way, the welding current value is determined by the wire feed rate, so if the wire material or diameter changes, the current required for the same amount of melting will naturally change. Therefore, completely different currents will flow even for the same amount of feed.

Furthermore, if the arc length changes for the same arc voltage due to a change in the shielding gas and its potential gradient, the length of the wire protruding from the welding torch will change, resulting in a change in the potential gradient. When the amount of resistance heat generated by the current flowing through the wire increases or decreases, and the amount of wire melting relative to the welding current increases or decreases, the ratio between the wire feeding speed and the welding current at that time will also change. Become.

Furthermore, even if these external factors are the same,
Welding power sources, wire feeding devices, etc. have varying output fluctuation rates depending on the magnitude of their output values, so if the output voltage value differs, the welding current value will vary even for the same wire feeding speed. I become confused.

The above-mentioned phenomenon of different values is caused by using a feedback control system that controls the wire feeding speed based on the difference between the actual output current value and the set output value, instead of keeping the wire feeding speed at a constant value. It seems possible to solve this problem by configuring the following. However, in actual arc welding using a welding power source with constant voltage characteristics, the welding current changes extremely rapidly, so this welding current value is detected and fed back to the wire feeding speed to stabilize it. Very difficult to control. In order to stabilize this, it is possible to slow down the response speed of the feedback signal system so that the control system operates based on the average value, but this means that the necessary response speed cannot be obtained. , the result is unsatisfactory.

On the other hand, when performing open-loop control without any feedback on the output, sufficient response speed and stability can be ensured, but there is a large difference between the output value determined by the output setting value and the actual output value. Therefore, even if a scale is provided on the setting device, it is only a guide.

Therefore, in such an open-loop control system, if the applied welding method, welding equipment, material, etc. change, the actual output value will change variously for the same setting position of the output setting device, and the same Because of this, it was not possible to attach a correct direct reading scale to the output setting device.

Furthermore, when the output setting signal is supplied from another device such as a large welding device or a welding robot where the output setting device and the welding machine body such as a welding power source and wire feeder are installed separately, It is necessary that the command value of the output signal of the setting device and the command value of the signals that can be accepted by the welding machine body, which is the controlled object, completely match, and of course, if the types of these signals are different, Even if the types are the same, if the command values differ due to differences in rated capacity, etc., an output different from the command value of the output signal of the setting device will be generated. For this reason, these large welding devices and welding robots
The welding power source, wire feeding device, etc. that are combined with these are limited to equipment with specific characteristics,
There was almost no freedom in combining equipment.

<Means for Solving the Problems> The present invention provides one or more welding conditions that occur during welding, the value of an output setting signal that sets the output of a welding machine, and the output control corresponding to the setting signal under the same conditions as that condition. When the value of the output setting signal under a certain welding condition is specified, the control reference signal corresponding to the setting signal under the same conditions is stored as a set of data. When the output value is determined by reading and the output value is obtained based on the value of this reference signal, if the specified set output value and the actual output value do not match, the direction in which the difference between the two decreases By repeating the process of correcting the value of the reference signal and obtaining the output using the reference signal with this corrected value, the actual output value approaches the set output value, and the actual output value approaches the set output value. The present invention proposes a welding machine control device in which the value of the reference signal when the values become equal is rewritten with the value of the reference signal previously stored. change,
Regardless of the welding machine used in combination, it is possible to always obtain an actual output value that matches the output value set in the output setting circuit.

<Example> FIG. 1 is a configuration diagram showing an example of implementing the present invention regarding setting of a welding current value. In the figure, 1 is an output setting circuit, which sets the output current setting value Is, which is determined by control signals such as voltage value, number of pulses, and frequency, based on other conditions such as output voltage value, type of consumable electrode wire, and shielding gas. The type and type of welding torch used are set in the output setting circuit, and a setting signal is output. Of course, if the conditions of these wires, gas, etc. are constant, the value of the output signal of this output setting circuit may be simply a combination with the output voltage value. Reference numeral 2 denotes a memory circuit that stores the value of the output current control reference signal (hereinafter referred to as reference signal value) Ir for each set value of the output setting circuit 1; 3 indicates the output setting circuit 1 for the memory circuit 2; A reference signal search circuit 4 searches for and reads out a reference signal value corresponding to a set value from the reference signal search circuit _. 5 is a reference signal correction circuit for correcting in a direction to reduce the difference between the two when they do not match, and 5 is a welding output control circuit for controlling the welding current value according to the output value of the reference signal correction circuit 4. be. This welding output control circuit 5 is, for example, a welding power source in a welding machine that uses a power source with constant current characteristics, and is used for arc welding that feeds the consumable electrode wire at a predetermined constant speed using a power source with constant voltage characteristics. In the machine, it is a wire feed speed control device. 6 is a load such as a welding arc or wire feeding mechanism, and 7 is a power source. Also, 8
is the actual output value I ₀ and the output setting value of output setting circuit 1
Is, and supplies the result to the reference signal correction circuit 4. Based on this result, the reference signal correction circuit 4 adds or subtracts a certain amount Δi from the reference signal value Ir to create a new standard. It is supplied to the welding output control circuit 5 as a signal value Ir'.

The operation of the embodiment shown in FIG. 1 will be explained according to the flowchart shown in FIG. 2. In the output setting circuit 1,
When the output current setting value Is is specified together with other welding conditions that occur during welding, the search circuit 3 reads out the reference signal value Ir corresponding to the output current setting value Is that meets these conditions from the storage circuit 2, The signal is supplied to the reference signal correction circuit 4. Since the output current value has not yet been detected in the reference signal correction circuit 4, the read reference signal value Ir is transmitted as is to the welding output control circuit 5. In the welding output control circuit 5, the power of the power source 7 is adjusted according to the reference signal value Ir, and is supplied to the load 6. The load 6 is driven by the output of the welding output control circuit 5, and the actual output current value _I0 at that time is detected, fed back to the comparison circuit 8, and compared with the output setting value Is of the output setting circuit 1. Here, if Is=I ₀ , the reference signal correction circuit 4 continues to supply the original value to the welding output control circuit 5 without changing the reference signal value Ir at that time. When the actual output current value is insufficient and I ₀ < Is, the reference signal correction circuit 4 adds a certain increment Δi to the reference signal value Ir, and calculates Ir′=Ir+Δi
It is corrected and supplied to the welding output control circuit 5. Conversely, when the actual output current value is excessive and I ₀ > Is,
The reference signal correction circuit 4 supplies a value Ir' = Ir - Δi, which is obtained by subtracting a certain amount Δi from the original reference signal value Ir, to the welding output control circuit 5 as a new reference signal value.
When the welding output control circuit uses a thyristor to phase control the output of the power source 7 and supply it to the load 6, the timing for correcting this reference signal value is synchronized with the AC voltage phase of the power source 7. That's fine. Further, when the welding output control circuit 5 performs analog control such as a transistor, a clock oscillator is provided in the reference signal correction circuit 4 so that the welding output control circuit 5 performs the welding output control circuit 5 at a constant cycle. By repeating such correction operations, the actual output value I ₀ will eventually match the output setting value Is. When this state in which the actual output value I ₀ matches the output setting value Is continues for a certain period of time, the storage circuit 2 takes in the output Ir' of the reference signal correction circuit 4 at that time and updates the stored contents. As a result, the actual output current value is self-learned and stored so that it becomes the output current value of the output setting value correctly. Therefore, from the next time onwards, when the same combination of output current value and other welding conditions is specified, the optimal set value will be output as the reference signal from the beginning. In addition,
As can be seen from the above operation, the reference signal value initially stored in the memory circuit 2 may be zero, and in this case, the output current value also starts from zero, and naturally I ₀
<Is, so the reference signal values are sequentially corrected in the increasing direction to reach the output setting value.

Therefore, unlike ordinary data storage/reproduction type devices, the device of the present invention does not require any data input work at the time of device manufacture, and can be self-learning by following the above-mentioned procedures at the site of use. Bye.

If you perform self-learning as described above for each setting value,
In the memory circuit 2, a reference signal with a value suitable for each case is stored, and during subsequent use, such a correction operation is hardly performed, and the output value correctly matches the output setting value from the start of welding. A reference signal of a value from which an actual output value is obtained is obtained. At this time, since the reference signal value is a value that provides an approximately correct set output value, there is no need to perform the correction operation of the reference signal value itself very quickly, and the control should focus on stability rather than responsiveness. It can be carried out.
As a result, the comparison circuit 8 and the reference signal correction circuit 4
The response speed of the output can be set to be sufficiently slow to perform corrective action according to the average value over a relatively long period of output changes, allowing extremely stable control without hunting even in arc welding with rapid changes. It becomes possible. Moreover, the control of welding output itself is
Since the correction operation of the reference signal value is slow, it becomes almost open-loop control in the transient state, so in the conventional closed-loop control method that performs feedback control, the response speed is slowed down to stabilize the control system. The delay at the rise of the output as in the case is almost eliminated.

In the embodiment shown in FIG. 1, each value of the reference signal is stored in correspondence with each value of the output setting value, but in this way, even if the output setting value changes slightly, , the user will go through a self-learning process again to obtain the correct reference signal value. For this reason, when a new output setting value is specified, the reference signal value increases from zero, resulting in a slow response and a slow rise, which may be inconvenient in practice. Furthermore, the number of combinations of welding condition data to be stored is extremely large, which not only requires a large storage capacity, but also requires a long time to search and read the reference signal value corresponding to the set value, and If you change the output setting value, it will not be able to respond. Therefore, as the welding condition data to be stored, only the data for each interval of change values of a certain welding condition is stored, and when the output value is set, 2
Read the data of two welding conditions, calculate the approximate reference signal value from this approximate data by proportional calculation, use this result as the reference signal value, and then make corrections as explained in the example of Fig. 1. The circuit may be configured to correct the value to a value that provides a correct actual output value.

FIG. 3 shows an example in which this is done. In the figure, numeral 9 denotes a closest binary search circuit that receives a signal from the output setting circuit 1 and reads out two reference signal values close to the output setting value from the storage circuit 2; This is a proportional calculation circuit that calculates a reference signal value adapted to the output of the output setting circuit 1 from the two reference signal values obtained by proportional calculation, and this nearest binary value search circuit 9
The proportional calculation circuit 10 corresponds to the reference signal search circuit 3 of the embodiment shown in FIG. The other parts of FIG. 3 are as follows in the embodiment shown in FIG.
It has the same function as the circuit with the same symbol.

The operation of the embodiment shown in FIG. 1 will be described with respect to control of the output current value in the same manner as the embodiment shown in FIG. In the figure, when the output setting value Is is output from the output setting circuit 1, the nearest binary search circuit 9 searches the storage circuit 2 using this output setting signal Is, and searches the storage circuit 2 for each condition stored previously. From the data of combinations of output setting values and reference signal values corresponding to each of those conditions, two output setting values that are close to the output setting value Is under the specified conditions and the same output as the specified conditions. Read out the reference signal value corresponding to the set value. These two sets of read data are supplied to the proportional calculation circuit 10 together with the output setting value Is. The proportional calculation circuit 10 performs proportional calculation on the reference signal value for the designated output setting value Is, assuming that it is on a straight line connecting these two sets of data, to obtain the reference signal value Ir. Now, the two sets of data read for the output setting value Is are (Is1, Ir1) and (Is
2, Ir2), the reference signal value Ir adapted to the output setting value Is obtained from this is:
In the diagram in Figure 4, with the output setting value Is on the horizontal axis and the reference signal value Ir on the vertical axis, the point (Is1, Ir
1) and the point (Is2, Ir2).

That is, Ir=Ir2−Ir1/Is2−Is1·(Is−Is1)+Ir1 is calculated. The reference signal value Ir thus obtained is supplied to the welding output control circuit 5 via the reference signal correction circuit 4, and the actual output value for the load 6 is controlled. This actual output value is equal to the output setting value
Is is compared with the comparison circuit 8, and if there is a difference, the reference signal correction circuit 4 changes the reference signal value.
Ir is corrected by a predetermined amount so that Ir=Ir±Δi, which is again supplied to the welding output control circuit 5, and the same correction operation as explained in FIG. 1 is repeated one after another. In this way, the correction operation is performed until the actual output value I ₀ matches the output setting value Is, and when the period of Is = I ₀ continues for a certain period of time, the reference signal value Ir at this time is changed to the output setting value Is. It is also written into the memory circuit 2. In this way, each time a new output setting value is specified, a temporary reference signal value is calculated from the two most recent sets of data, and this is repeatedly revised while being compared with the actual output value. Data is accumulated in the circuit. In this case, output values are specified in advance at regular intervals, data for the entire range of output values is accumulated, and the memory circuit is rewritten only when the data for these specific output values is modified. When another intermediate output value is specified, the capacity of the memory circuit 2 can be reduced by only calculating and modifying the reference signal value and not writing to the memory circuit. . In addition, in the initial stage of data accumulation,
Since the memory content of the memory circuit 2 is zero, the reference signal value obtained by the calculation will also be zero, but in this case as well, the output value only starts from zero and will not reach the final value. Eventually, the output will reach the set value.

In each of the above embodiments, in order to simplify the explanation, the case where the present invention is implemented is explained regarding control of only the actual welding output value _I0 .
In actual welding, in addition to the output current, there are other welding conditions such as output voltage and welding speed, so by doing the same as above, it is possible to obtain optimal reference signal values for each of these conditions.

In a welding machine that uses a power supply with constant voltage characteristics to supply the consumable electrode wire at a substantially constant speed, as mentioned above, the welding voltage value is determined by the output voltage value of the welding power source, and the welding current value is approximately proportional to the wire feeding speed, the reference signal value of the welding voltage is the output voltage value of the welding power source, and the reference signal value of the welding current is the wire feeding speed. On the other hand, in a welding machine that uses a power supply with constant current characteristics and controls the arc voltage by the feeding speed of the consumable electrode wire, the reference signal value of the welding voltage is the wire feeding speed, and the welding current The reference signal value is the output current value of the welding power source. In addition, in non-consumable electrode arc welding that uses a tungsten electrode as an electrode, a power source with constant current characteristics is used, so the reference signal value of the welding current is similarly the output current value of the welding power source, and the reference signal value of the welding voltage is the arc It is the distance between the electrode and the workpiece that determines the arc length for controlling the voltage. Furthermore, when controlling the heat input per unit length of the welding wire, it is sufficient to maintain the relationship between the product of the welding current and welding voltage and the welding speed at a predetermined value, so the welding current and welding voltage can be specified. When this happens, the speed reference signal value is read out from the welding speed corresponding to these products, and the same correction as described above is applied to determine the appropriate value.

In the above explanation, the reference signal correction circuit 4 operates immediately after welding is started, but in arc welding, when welding is started, short circuits and fusing between the electrode and the welded object occur. Since transient phenomena such as opening and opening occur, there are periods when both the welding voltage and welding current are unstable. For this reason, if the reference signal correction circuit 4 is operated immediately after the start of welding, unnecessary corrections may be made, which may even make the control system unstable. Such instability can be reduced by slowing down the response speed of the reference signal correction circuit 4, but there is a limit to slowing down the response speed too much because the correction operation during steady state will also become slow. Therefore, the function of the reference signal correction circuit 4 is stopped for a certain period of time from the start of welding when unstable phenomena are likely to occur, and after the unstable period has elapsed, the reference signal correction circuit 4 is operated and the output set value is set. By modifying the reference signal value by
The invention can be practiced. Similarly, at the end of welding, the correction operation is first stopped by the end command, and then the welding output value is reduced and stopped.

<Effects of the present invention> As described above, in the present invention, the output setting value supplied to the control circuit of the welding machine body is adjusted until the set value output value of the output setting device matches the actual output value. Since the reference signal value is corrected sequentially,
The output value determined by the setting value of the setting circuit now matches the actual output value, and the scale of the setting circuit can be unilaterally determined to provide a direct reading scale, regardless of the sensitivity of the control circuit of the combined welding machine body. It can be done.

Moreover, once the welding machine bodies to be combined are determined, they will not be changed much thereafter, so once the relationship between the output setting value and the reference signal value is memorized for this combined machine through self-learning, From then on, the optimal reference signal value will be output from the beginning, and the control system will become close to an open-loop control system, making it possible to provide extremely fast response that cannot be achieved with a normal feedback control system. .

In addition, each device or circuit until the reference signal value is input can be manufactured independently of the welding output control circuit of the welding machine main body, so for example, when combining a welding power source and wire feeder with a welding robot, By providing a circuit that generates a reference signal value to which the present invention is applied to the control circuit of a robot, it is possible to use various devices with different rated capacities, output fluctuation rates, specifications, etc. in combination. Become. As a result, the range of application of combined equipment such as a power source and wire feeding device to the welding robot is extremely wide, resulting in a highly flexible device. Moreover,
For this combination target, if the type of reference signal is the same, the signal value, that is, the sensitivity, is automatically compensated by modification and storage, so even if the manufacturers of welding machines are different, special There is no need to match the ratings and specifications of the welding machine. Usually, this reference signal value is often supplied by a direct current voltage, making it possible to freely combine most current devices.

When these devices are combined, the optimal reference signal value for the set value is sequentially accumulated through self-learning, so there is no need to perform any adjustment or inspection between each device, and it can be done at the site of use. Even if you temporarily combine a welding machine on hand, you can obtain a sufficiently correct output.

It is also possible to incorporate these functions into a welding power source, wire feeding device, etc. In this case,
Regardless of the signal value required for the welding output control circuit, it is possible to set the output setting circuit to a convenient signal value range for setting, and it is completely the same even for many models with different output ratings. Since it is possible to use a control system, the control system from the output setting circuit to the reference signal control circuit can be used in common for all ratings, making it possible to standardize control devices and improve production. It has excellent effects on properties, uniformity of quality, etc.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flowchart for explaining the operation of the embodiment of FIG. 1, and FIG. 3 is a block diagram showing another embodiment of the present invention. FIG. 4 is a diagram for explaining the operation of the proportional calculation circuit used in the embodiment of FIG. 3. 1... Output setting circuit, 2... Memory circuit, 3...
Reference signal search circuit, 4...Reference signal correction circuit, 5
... Welding output control circuit, 6 ... Load, 8 ... Comparison circuit, 9 ... Proximity binary search circuit, 10 ... Proportional calculation circuit, Is ... Output (current) setting signal or output (current) setting value , Ir...Reference signal or reference signal value for output control, _I0 ...Actual output value.

Claims (1)

[Scope of Claims] 1. An output setting circuit that sets an output value of a welding machine together with one or more welding conditions that occur during welding, and an output setting value under the one or more welding conditions and an output control circuit corresponding to the output setting value. a storage circuit that stores a reference signal value as a set of data; and a reference signal of the same set of data as the output setting value from the storage circuit by specifying an output setting value of the welding machine together with the one or more welding conditions. a reference signal search circuit that reads out the value of the reference signal; and a reference signal search circuit that compares the set output value of the output setter with the actual output value, and increases the reference signal value stepwise at predetermined intervals until the set output value and the actual output value match. A welding machine control device comprising: a reference signal correction circuit that corrects the value of the reference signal; and a welding output control circuit that controls an output value of the welding machine based on the value of the corrected reference signal. 2. The welding machine according to claim 1, wherein the memory circuit is a circuit that takes in the value and rewrites the stored value when the output of the reference signal correction circuit does not change continuously for a certain period of time. Control device. 3. The storage circuit is a storage circuit that simultaneously stores one or more welding conditions that occur during welding as well as an applied welding method as one set of data, and the reference signal search circuit stores the output of the output setting circuit. Claim 1 or 2, which is a search circuit that searches for a reference signal corresponding to a combination of a signal and the welding method from data stored in the storage circuit and supplies it to the welding output control circuit. The welding machine control device according to any one of the above. 4. The memory circuit is a memory circuit that simultaneously stores one or more welding conditions that occur during welding as well as the characteristics of the applied welding machine as one set of data, and the reference signal search circuit stores other search conditions. and the characteristics of the welding machine, the circuit searches the data stored in the storage circuit for a reference signal and supplies the welding output control circuit to the welding output control circuit. The welding machine control device according to any one of the above. 5. The reference signal search circuit has an arithmetic function that reads out two sets of data having values close to the set value of the output setting circuit, calculates the value of the reference signal corresponding to the set value from the read data by proportional calculation, and outputs the result. A welding machine control device according to any one of claims 1 to 4, which is a circuit having: