JPH0367791B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a welding wire delivery device that is delivered to a weld as a consumable electrode or filler metal. In the arc welding method, in order to stably feed the welding wire to the welding area, it is necessary to make the distance from the wire feeding device to the welding area, that is, the welding torch, as short as possible. On the other hand, from the viewpoint of workability, it is desirable that the wire feeding device, which is large in weight and shape, be located away from the welding torch. Due to these conflicting demands, the distance is usually limited to about 6 m, and in order to feed the welding wire over a longer distance, it is necessary to install multiple wire feeding devices in the welding wire feeding path and send the welding wire over a long distance. A push-pull feeding method is used to smooth the feeding by compensating for the increase in feeding resistance along the feeding path.

In such a push-pull type welding wire feeding device, usually only a specific wire feeding motor, for example, the motor closest to the welding torch, that is, the motor on the pull side, is operated at various constant speeds determined by the welding conditions. The wire feeding motor close to the wire sending side of the feeding path, that is, the pusher side, is configured to be controlled at a constant torque so as to operate at a constant torque. Generally, the motor that is subject to constant torque control is controlled so that the generated torque is kept approximately constant regardless of changes in rotational speed by feeding back the armature current and keeping it constant. On the other hand, the inventor investigated the relationship between the wire feeding speed and the required motor torque using a device that is close to practical, and obtained the results shown in FIG. In Figure 1, the horizontal axis is the feeding speed v
, the vertical axis shows the motor torque T, and the required torque with respect to the speed is shown by the curve A. As can be seen from the figure, the motor torque required for feeding increases approximately in proportion to the square of the speed. Although the reason for this is not clear, it is thought that the component that is a function of speed occupies a relatively large area among the various frictional forces in the feed path. With respect to the required torque that changes in this way, if the push side motor is controlled at a constant torque as shown in Figure B, the generated torque required for the pull side motor, which is controlled at a constant speed, will be as shown in curves A and B. The torque corresponds to the difference, and increases rapidly as the speed increases. On the other hand, since the output of the motor is proportional to the product of the generated torque and the number of rotations, the rated output required of the pull-side motor that is controlled at a constant speed is the maximum value of the difference between curves A and B in Figure 1 and the speed. It is necessary to select a large value corresponding to the product of . For this reason, the wire feeding device on the pull side becomes large in size, which is not only inconvenient to operate and move, but also inevitably results in a deterioration in response speed due to the use of a large motor.

For such conventional devices, in order to equalize the load sharing of each motor on the push side and pull side according to changes in the load on the feed path, for example,
As seen in Japanese Patent Publication No. 49-38421, the push-side and pull-side motors are both driven by the same power source or a power source controlled by the same control signal, or as shown in Japanese Patent Publication No. 46-43971. ,
As seen in JP-A-54-112755 and JP-A-56-30082, the load condition of the motor that is controlled at constant speed is detected as the armature current of the motor that is controlled at constant speed. A method has been proposed that controls the generated torque of a motor that is subjected to constant torque control in accordance with a detected load state. However, in the former case where the same power source or the same control signal is used, each motor is controlled at a substantially constant speed or a motor whose speed decreases less as the torque increases, so both motors influence each other. There was a drawback that sufficient constant speed feeding could not be obtained. The latter method detects the armature current of the constant speed motor,
Theoretically, it should be possible to obtain good feeding, but the stability was poor and it was not practical. In other words, push
In welding machines that feed welding wire using the pull method, there is generally a long distance between the push side motor and the pull side motor of 10 m or more, sometimes over 30 m, and there is no wire between them in the feeding path. There is slack and temporary changes in frictional resistance, large fluctuations in the motor armature current, and the pull-side motor current does not necessarily correspond to the feeding speed, making the feedback control system extremely unstable. It wasn't practical.

The first aspect of the present invention is to control the feed speed by controlling the pull side motor at a constant speed and controlling the generated torque of the push side motor to a torque including a component corresponding to the feed speed of the electrode wire. This structure compensates for changes in the required torque of the feed path that occur due to changes in the torque by mainly changing the torque generated by the pusher motor.
It is possible to reduce the capacity and weight of the pull-side motor as much as possible, and it is easy to operate and move, and it is possible to perform extremely stable feeding. In addition to the first aspect, the second aspect of the present invention improves transient characteristics by adding the speed fluctuation signal of the pull side motor to the torque setting signal of the push side motor.

FIG. 2 is a connection diagram showing an embodiment of the first invention of the present invention. In the figure, 1 is a wire reel in which a welding wire 2 is wound into a coil and fed out one after another, and 3 is a pusher motor installed near the wire reel side of the feed path, which is mechanically connected to the wire reel. The wire is sent out by the feed roll 301.
Reference numeral 4 denotes a pull-side motor provided on the welding torch 5 side of the feed path, which pulls out the welding wire by a feed roll 401 and supplies it to the welding torch 5. A flexible conduit 6 serving as a guide is provided between the feed roll 301, the feed roll 401, and the welding torch 5, respectively. 7 is a feed speed setter, 8 is a comparator, 9 is an amplifier, and 10 is a speed detector for detecting the rotational speed of the pull-side motor 4. Further, numeral 11 is a minimum torque setting device for setting the minimum torque of the push side motor, but it can be omitted if the speed range does not extend to low speeds. 12 is an adder, 13 is a comparator, 14 is an amplifier, and 15 is a torque detector, which is a current detector for detecting the armature current of the push side motor 3. 16 is a coefficient unit which applies a coefficient k (k≠0) to the output of the feed speed setting unit 7.
, and then supplies the result to the adder 12. In the example shown in the figure, the pull-side motor 4 compares the output V _r of the feed speed setting device 7 with the output of the speed detector 10, for example, the armature voltage V _f of the pull-side motor 4, and generates a difference signal.
The speed is controlled by the amplified V _r −V _f by the amplifier 9 to the speed set by the feed speed setting device 7 . On the other hand, the output V _r of the feed speed setting device 7 is multiplied by the coefficient k in the coefficient unit 16 and added to the output T _n of the minimum torque setting device 11 in the adder 12 to obtain a torque setting signal T _r =T _n +kV _r becomes. This torque setting signal T _r is compared with the output T _f of the output torque detector 15 of the pusher motor 3 by a comparator 13, and a difference signal is calculated, which passes through an amplifier 14 and becomes a reference signal for driving the pusher motor 3. Here, the coefficient k is the length and structure of the conduit 6, the shape of the welding wire,
Select the material appropriately. FIG. 3 is a diagram showing the relationship between torque T and feeding speed v when the present invention is carried out, and similarly to the diagram shown in FIG. 1, curve A shows the torque required for feeding. With respect to the required torque that changes as shown by curve A, the torque generated by the pusher motor 3 is generated using (T _n + kV _r ) as the torque setting signal and includes a component directly proportional to the feeding speed, as shown in Figure C. Then, the torque required for the pull side motor 4 is only the torque equal to I-H as shown in curve D, and even if the feeding speed increases, the torque required for the pull side motor 4 does not increase much. Become something. At this time, the torque actually required for the pull side motor 4 is the loss caused by the motor and reduction gear itself added to this, but even if these are added, the output required for the pull side motor 4 is small. It turns out.

In the embodiment shown in FIG. 2, the coefficient multiplier 16 is one that multiplies the output V _r of the feed speed setter 7 by k, but the coefficient k is not limited to a constant; It may be a variable proportional to the output V _r of No. 7. In this case, the torque generated by the push side motor 3 has a shape similar to the change characteristic of the required torque corresponding to the welding wire feeding speed, as shown by the broken line C' in FIG. The output torque of the motor 4 can be independent of the feeding speed or torque that is inversely proportional to the feeding speed, as shown by the broken line D' in Figure 3, and the output of the pull-side motor can always be constant. .

When using the embodiment shown in Fig. 2, the push motor can bear the increase in torque required for increasing the welding wire feeding speed, so that the intended purpose can be achieved in an equilibrium state. can be reached. However, even without changing the set value of the feed speed, the feed resistance may change due to external factors such as temporary changes in the feed path conditions such as changes in the curvature of the flexible conduit. The feeding power also changes. Therefore, in the embodiment shown in FIG. 2 in which the speed component is added to the torque setting signal, this necessary change in feeding force is not compensated for by the push side motor, but is entirely transferred to the pull side motor. Therefore, you will have to bear the burden. The load on the pull-side motor is reduced even when the wire feeding speed is accelerated or decelerated due to temporary changes such as this or when the setting value of the feeding speed is changed. The second invention is a device that can be used as a device, and a connection diagram of this embodiment is shown in FIG. In this figure, parts having the same functions as those in FIG. 2 are given the same reference numerals. 16 and 17 are coefficients k ₁ and _{k 2 ( k 1 ≠ 0} ,
₁₈ is an adder that adds the output T _n of the torque setting unit 11, the output k ₁ V _r of the coefficient unit 16, and the output k ₂ v of the coefficient unit 17.
In the device shown in the figure, the operation of the pull side motor 4 is as follows.
Since it is the same as the embodiment shown in the figure, the explanation will be omitted. The pusher motor 3 is configured to generate a predetermined torque determined by the output of the adder 18, T _r =T _n +k ₁ V _r +k ₂ v = T _n +k ₁ V _r +k ₂ (V _r −V _f ). Controlled by torque detector 15 and comparator 13. Therefore, in addition to the feed speed component, the push side motor 3 has a speed error v=V _r in the pull side motor when the resistance of the feed path 6 changes or the set speed changes.
Even when −V _f occurs, the generated torque changes in a direction to compensate for this, and operates to completely compensate for the change in the required torque required for the feed path. In the embodiment shown in FIG. 4, the adder 18 and the comparator 1
3, but using a set of operational amplifiers (T _n +
k ₁ V _r +k ₂ v−T _f ) may be calculated. Furthermore, although analog comparators 9 and 14 are used in the embodiments of FIGS. 2 and 4, it is also possible to use ones that control the output by chopper control according to the input signal. . Furthermore, when a plurality of push side motors are provided in the welding wire feed path, an adder 13 calculates the total torque generated by all the push side motors.
Alternatively, each motor may be controlled so as to control the torque according to the output signal 18. Also, amplifier 1
When a device that generates a constant current output according to an input signal is used as the torque detector 15 and the comparator 13, the torque detector 15 and the comparator 13 can be omitted.

As described above, in the present invention, the output torque of the pusher side motor that controls constant torque is determined according to the feeding speed of the welding wire, so the feeding force changes according to the change in the feeding speed. can be completely compensated by the output torque of the push side motor, so the pull side motor can have a small capacity, and the pull side wire feeder can be made smaller and lighter. A device with excellent operability and mobility can be obtained.
In particular, in the second aspect of the present invention, the torque of the push side motor is controlled in a direction that compensates for transient speed changes, so it is possible to obtain a device with extremely excellent responsiveness.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the relationship between feeding speed and required torque, Fig. 2 is a connection diagram showing an example when implementing the first invention of the present invention, and Fig. 3 is a diagram when implementing the present invention. FIG. 4 is a diagram showing the relationship between torque and feeding speed, and FIG. 4 is a connection diagram showing an example of implementing the second invention of the present invention. 3...Push side motor, 4...Pull side motor, 7...Feeding speed setter, 8, 13...Comparator, 9, 14...Amplifier, 10...Speed detector,
11... Minimum torque setter, 12, 18... Adder, 15... Torque detector, 16, 17... Coefficient unit.

Claims (1)

[Scope of Claims] 1. Welding wire is sent out by one or more push side motors provided on the supply side or in the middle of the welding wire feed path, and a pull side motor provided on the welding torch side of the feed path. A pusher that feeds the welding wire to the welding torch while drawing out the welding wire.
In a pull type welding wire feeding device, a welding wire feeding speed setting device, a pull side motor control circuit that controls the rotational speed of the pull side motor in response to an output signal of the welding wire feeding speed setting device; A torque setting device that sets the minimum value of the torque generated by the pusher side motor, and an input signal that is the sum of the output signal of the torque setting device and the signal corresponding to the output signal of the welding wire feed speed setting device. A welding wire feeding device comprising a pusher motor control circuit that drives the pusher motor with a torque corresponding to the torque. 2. A plurality of the pusher side motors are provided in the wire feeding path, and the total torque generated by all the pusher side motors is determined as a signal corresponding to the output signal of the torque setting device and the output signal of the welding wire feeding speed setting device. The welding wire feeding device according to claim 1, wherein the welding wire feeding device controls the torque according to the sum of the following. 3. The welding wire is sent out by one or more push side motors provided on the supply side or in the middle of the welding wire feed path, and the welding wire is sent out by the pull side motor provided on the welding torch side of the feed path. In a push-pull type welding wire feeding device that feeds the welding wire to the welding torch while being pulled out, the welding wire feeding speed setting device, the welding wire feeding speed detector,
a subtractor that calculates a difference between the output signal of the welding wire feed speed setting device and the output signal of the welding wire feed speed detector; and a rotation speed of the pull side motor according to the output signal of the subtractor. A pull-side motor control circuit to control, a torque setting device to set the minimum value of the generated torque of the push-side motor, an output signal of the torque setting device, an output signal of the subtracter, and a welding wire feed speed setting signal. A welding wire feeding device comprising: a push side motor control circuit which receives as input the sum of a signal corresponding to the input signal and drives the push side motor with a torque corresponding to the input signal. 4. When a plurality of the push side motors are provided in the wire feeding path, the total amount of torque generated by all the push side motors is calculated as the output signal of the torque setting device, the output signal of the subtracter, and the welding wire feeding speed setting. The welding wire feeding device according to claim 3, wherein the welding wire feeding device controls the torque according to the sum of the output signal of the welding wire and the signal corresponding to the output signal of the welding wire.