JPH02121776A - Welding wire feeder - Google Patents

Abstract

PURPOSE:To stably feed a welding wire even if the welding position is changed by constituting a wire driving part of a driving device using piezoelectric elements. CONSTITUTION:When the AC voltage with the phase difference is applied on the respective piezoelectric elements 16 and 16', a wire contact part 18 carries out elliptical motion in the arrow direction. When the welding wire 7 is sandwiched between the contact part 18 and a freely rotatable pressing roller 2, the contact part 18 carries out elliptical motion by expansion and contraction of the piezoelectric elements 16 and 16', by which the welding wire 7 is fed toward a nozzle part.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a welding wire feeding device, and particularly to a welding wire feeding device for a welding robot suitable for stably feeding a welding wire even when the welding posture changes. The present invention relates to a welding wire feeding device.

[Conventional technology]

Regarding conventional welding wire feeding methods, for example, supervised by Keizo Tezuka, [Welding Work Manual], Sankaido, 1968
Various mechanisms are described in Pages 34 to 36 published in November 2013.

The welding wire is fed within the welding cable from the wire reel to the tip of the welding torch by a wire feed motor and a feed roller connected to the wire feed motor.

FIG. 8 is a configuration diagram showing a conventional welding wire feeding system.
The feeding methods are classified according to the position where the feeding motor 21 for feeding the welding wire is placed, and (a) is the bushing method, (b) is the pull method, and (c) is the bushing-pull method. This is what is shown.

The welding wire 7 pulled out from the wire reel 22 passes through a feeding roller 32 and a pressure roller 33 connected to a feeding motor 21.
The welding torch 25 is held in the conduit cable 24 and fed to the nozzle part 31 of the welding torch 25. Although FIG. 6 shows a method for semi-automatic welding, each method is applied depending on the application.

Arc welding robots often use a semi-automatic welding method.

FIG. 9 is a configuration diagram of a welding wire feeding device for a welding robot on a boat.

As shown in FIG. 9, the wire reel 22 is provided separately from the feed motor 21 mounted on the robot arm 26, and the welding wire 7 is pulled out from the wire reel 22 by the motor and welded. It is fed to the tip of the torch 25. This method corresponds to the Bush method shown in FIG. 8(a).

Furthermore, in some cases, only the welding torch 25 is attached to the robot's wrist in order to reduce the load on the robot arm 26, as in the example described in Japanese Utility Model Application Publication No. 63-53369.

In the welding method using these welding wires 7, a welding power source with so-called constant current characteristics, in which the amount of change in welding voltage is small with respect to changes in welding current, is generally used. Accordingly, welding wire 7 is also fed continuously at a constant speed.

In addition, in the case of special welding methods such as pulsed arc welding, it is necessary to feed the welding wire intermittently according to changes in the welding current, and for this purpose, the feeding motor 21 is repeatedly rotated and stopped as appropriate. Compatible.

[Problem to be solved by the invention]

A conventional wire feeding device for a welding robot is constructed as shown in FIG. Therefore, the following problems occurred during welding or teaching.

Welding wire 7 is fed to the tip of welding torch 25 through conduit cable 24 by feeding motor 21 .

During welding, there is no problem if the position of the welding torch 25 changes little, but if the welding position or posture changes, the conduit cable 24 through which the welding wire 7 passes will be swung greatly, and the feed motor 21 will rotate at the same time. Even if the welding wire 7 is sent out at a constant speed by rotating several times, the welding wire 7 coming out from the tip of the welding torch 25 changes irregularly.
As a result, welding cannot be maintained stably, and the arc becomes unstable, causing welding defects such as spatter and bead irregularities.

In addition, in the case of pulsed arc welding, it is necessary to feed the wire intermittently according to the welding current waveform, but the distance between the feed motor and welding torch is long, making it difficult to make fine adjustments. was there.

The feed motor 21 is stopped during teaching.

The welding part is taught while the amount of protrusion from the tip of the welding torch 25 is kept constant. At this time.

Since the amount of wire protruding from the welding torch 25 changes depending on the condition of the conduit cable, accurate position teaching will be hindered.

Further, in the teaching method using wire touch sensing, the position of the wire tip changes every time the wire tip comes into contact with a welding workpiece (not shown), and there is a problem that accurate position detection cannot be performed.

As a means to solve these problems, welding torch 2
Although it is effective to provide the feed motor 21 near the welding wire 5, in the conventional drive system, the weight of the drive device becomes large in order to feed the necessary welding wire 7, and this places a burden on the wrist of the welding robot. This resulted in an economical problem as it was necessary to prepare a welding robot with a large load capacity.

Further, the welding wire 7 to be fed has its kinks corrected before and after the feed motor attached to the feed motor 21. The welding wire 7 is bent because it is wound around the wire reel 22.

In the feeding system shown in FIG. 9, the welding wire 7 fed out from the welding nozzle 7 depends on the condition of the conduit cable that reaches the welding torch 25 even if the bending is straightened by the feeding motor 21.
The bending condition of the wire is not uniform, which causes errors in the position of the wire tip during teaching and welding, making it difficult to perform accurate welding.

The present invention has been made in order to solve the problems of the prior art described above, and is a welding wire supply device for a welding robot that incorporates a drive device in a welding torch that can eliminate changes in the welding wire protrusion length. Its purpose is to provide a device.

[Means to solve the problem]

In order to achieve the above object, the welding wire feeding device according to the present invention basically includes a plurality of wire drive parts between a wire reel and a welding torch, and at least one
The wire driving section is constructed by a driving device using a piezoelectric element.

Furthermore, in a robot body that is equipped with at least one of a wire feeding device that sends welding wire to a welding torch and a welding torch, the wire drive unit is configured with a piezoelectric element, and the wire drive unit is installed inside the welding torch body. It is prepared for.

[Operation] According to the above technical means, since the driving part of the welding wire feeding device is constructed with a piezoelectric element, the feeding device is small and lightweight, and can be installed inside the welding torch body, so that welding of the welding wire can be performed easily. The protrusion length from the torch tip is not affected by the condition of the conduit cable.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 is a longitudinal sectional view of a welding torch section of a welding wire feeding device according to an embodiment of the present invention, FIG. 2 is an enlarged view showing the wire drive section of FIG. 1, and FIG. FIG. 2 is a sectional view taken along line AA' in FIG. 2;

As shown in FIG. 1, the welding wire 7 is
A conduit cable 8 consisting of a signal cable and a current carrying section (not shown) passes through the wire drive section 1 consisting of a piezoelectric element 16, 16' and a contact section 18, and a pressure lever 4. Pressure roller 2° spring 5. Pressure adjustment nut 6
It is held between a wire pressurizing section constituted by a wire pressurizing section, and is fed to a nozzle section (not shown) via a wire guide 9.

On the other hand, the current for welding passes through the conductive part in the conduit cable 8 and the welding torch body 3, and passes through the curved guide 10.
It reaches a power supply tip (not shown) provided in the nozzle portion, and is supplied with power to the welding wire 7. 13 is a shielding gas inlet, which is a gas inlet that protects the arc during welding from the atmospheric atmosphere; 14 is a mounting jig for attaching the welding torch 25 to the robot wrist (not shown); 12 is an insulating coating, and 12 is a bearing.

The piezoelectric elements 16 and 16' are of a laminated type, and have the characteristic that their dimensions expand in the laminated direction when a voltage is applied to them, return to their original size when removed, and contract when a voltage of opposite polarity is applied. The piezoelectric elements 16, 16' are arranged facing each other at an arbitrary angle, and are orthogonally arranged in this embodiment, but when an AC voltage with a phase difference is applied to each piezoelectric element 16, 16', the wire contact portion 18 Then, it makes an elliptical motion in the direction of the arrow shown in FIG. When the welding wire 7 is held between this and the rotatable pressure roller 2, the contact portion 18 moves in an elliptical manner due to the expansion and contraction of the piezoelectric elements 16, 16', so that the welding wire 7 is moved toward the nozzle portion. will be sent.

The welding wire 7 is fed i (feeding speed) according to the welding current value.
In the present invention, this can be achieved by changing the frequency of the applied voltage value or by changing the applied voltage value at a constant frequency.

As shown in detail in FIG. 2, the piezoelectric elements 16°16' are
Since one end is fixed by the base 15, elongation due to voltage application appears only at the other end. As mentioned above, since the wire contact part 18 makes an elliptical movement, the connection part 17 is structured to be rigid in the stacking direction of the piezoelectric elements 16, 16' and flexible against lateral forces, so that the piezoelectric elements 16. No lateral force is applied to 16'.

The welding wire 7 is fed in the direction of the welding nozzle as shown by arrow a in FIG. 2, but the welding tip is replaced.

There are cases where the wire is exchanged, etc. and the wire is fed in the opposite direction (arrow b). In such a case, it is sufficient to reverse the phase of the voltage applied to the piezoelectric elements 16 and 16', which can be easily done by adjusting the phase or by switching the voltage applied to the piezoelectric elements 16 and 16'. It can be achieved.

As shown in FIG. 3, the welding wire 7 usually has a circular cross section, and in order to maintain a stable contact state with the contact part 18 and to provide the correct feeding direction of the welding wire 7, the welding wire 7 is welded. A groove having an arcuate cross section that matches the diameter of the wire 7 is formed in the wire contact portion 18. Since the wire contact portion 18 is constantly in contact with the welding wire 7, it is conceivable that wear may occur, or it can be ignored because the pressing force is applied by the pressure roller 2 provided opposite to the wire contact portion 18. However, if you use it for a long time, you may not be able to ignore it. In that case,
Use wear-resistant materials or even contact parts 18
The structure may be such that it is possible to exchange the parts.

In this embodiment, a groove is provided in the contact portion 18, but the pressure roller 2
A similar groove may be configured in the.

During welding, stable feeding of the welding wire 7 is the first condition for stably maintaining the welding arc. In particular, when the welding current value is in a relatively low range of about 100 A, stability in feeding the welding wire 7 is strictly required. As a means for realizing stable feeding of the welding wire 7 according to this embodiment, a roller shaft 19 supporting the pressure roller 2 is configured to rotate at the same time as the pressure roller 2, and the roller shaft 19 is provided with a rotation detection device. device (e.g. encoder or tacho generator)
is attached, and the piezoelectric element 16 is activated by the output signal of the rotation detector.
．． The method of changing the applied voltage value at a constant frequency can be realized by feeding back the voltage applied to the voltage regulator 16' to a frequency regulator (not shown).

According to this embodiment, since the portion for feeding the welding wire is constituted by a piezoelectric element, the following effects can be achieved.

Since a piezoelectric element is used in the drive section of the feeding device, it can be made small and lightweight, and the feeding device can be integrated with the welding torch. Therefore, even if the conduit cable moves violently due to the operation of the welding robot, the welding wire can be fed without any change, the arc is always maintained constant, and welding defects can be eliminated. Furthermore, configuring the wire feeding device within the welding torch can significantly improve the accuracy of wire touch sensing during teaching.

Next, FIG. 4 is a schematic configuration diagram of a welding wire feeding device according to another embodiment of the present invention.

As shown in FIG. 4, the welding wire 7 is attached to the pail pack 4
2, and is fed to, for example, a welding torch 41 as described above in FIG. Normally, the pail pack 42 is often installed apart from the welding torch 41. In such a case, it is possible to feed the welding wire 7 more stably by using a plurality of feed motors such as the wire pull-out motor 43 and the intermediate feed motor 44. In this case, it is desirable that the feed motors 43 and 44 have constant torque characteristics, and the welding torch 41 as in the previous embodiment serves as the final feed section.
apply. Since the feeding device provided in the welding torch 41 has constant speed characteristics,? [The combination of constant torque characteristics and constant speed characteristics is convenient for a wire feeding device using a feeding motor system. The same applies when it is necessary to feed over a longer distance, and stable feeding is possible by using the feeding method of the previous embodiment in the final stage of a plurality of constant torque characteristic feeding motors.

Next, FIG. 5 is an enlarged view of a wire driving section according to still another embodiment of the present invention. In the figure, the same reference numerals as in FIG. 2 indicate the same parts as in the embodiments shown in FIGS. 1 and 2 above. Further, the wire drive section shown in FIG. 5 is installed within the welding torch main body as shown in FIG.

The wire drive section shown in FIG. 5 includes a pair of wire drive sections 1 and 1' facing each other with respect to the welding wire 7.

If voltages of different frequencies are applied to the respective wire drive parts 1 and 1', or if different voltages are applied at the same frequency, there will be a difference in the movement of the wire contact parts 18 and 18' that clamp the welding wire 7. The welding wire 7 is bent and fed in the direction of arrow C or C'. Therefore, it is possible to easily impart a bend to the welding wire 7 by simply observing the bend in the wire sent out from the welding nozzle section and changing the voltage frequency or voltage value applied to the drive section.

According to the embodiment shown in FIG. 5, the same effects as those of the embodiments shown in FIGS. be.

Moreover, FIG. 6 is an enlarged view of a wire drive unit according to still another embodiment of the present invention. In the drawings, the same numbers as in Fig. 2 indicate the same parts as the embodiments shown in Figs. 1 and 2. This embodiment has the function of driving the wire only in one direction (direction a). and the arrangement angle θ of the piezoelectric element with respect to the wire
is set between 30 degrees and 60 degrees. In this case, the a-direction component of the vibration amplitude generated by the piezoelectric element can be used as a driving force source, and the wire can be fed in one direction with a simple configuration.

Furthermore, FIG. 7 is an enlarged view of a wire driving section according to still another embodiment of the present invention, and is arranged at a predetermined angle (90 degrees The elastic support portion 40 is provided so that the elastic support portion 40 has an elastic support portion (preferably around 100 degrees). Note that the arrangement angle θ of the piezoelectric element with respect to the wire is preferably set between 30 degrees and 60 degrees as in the previous embodiment. According to this embodiment, the elastic support portion 40 prevents the vibration of the piezoelectric 16. Moreover, since it is possible to stop receiving the pressing force from the pressure roller 2, it is possible to prevent excessive bending stress from being applied to the piezoelectric element 16, and it is possible to improve the durability of the device.

〔Effect of the invention〕

As described above, according to the present invention, in the welding torch,
It is possible to provide a welding wire feeding device for a welding robot that incorporates a drive device that can eliminate changes in welding wire protrusion length.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a welding torch section of a welding wire feeding device according to an embodiment of the present invention, FIG. 2 is an enlarged view showing the wire drive section of FIG. 1, and FIG. 2 is a sectional view taken along line AA' in FIG. 2, and FIG. 4 is a schematic configuration diagram of a welding wire feeding device according to another embodiment of the present invention. FIGS. 5, 6, and 7 are enlarged views of a wire drive unit according to still another embodiment of the present invention, and FIG. 8 is an enlarged view of a wire drive unit according to another embodiment of the present invention. A configuration diagram showing a conventional welding wire feeding system, FIG. 9, is -
FIG. 2 is a configuration diagram of a welding wire feeding device for a boat-based welding robot. 1.1'...Wire drive unit, 2...Pressure roller, 3
... Welding torch body, 7... Welding wire, 16.1
6'... Piezoelectric element, 17... Connection part, 18.18'
Wire contact part, /par＼

Claims (1)

[Claims] 1. Welding characterized by having a plurality of wire drive sections between a wire reel and a welding torch, and at least one wire drive section being configured with a drive device using a piezoelectric element. Wire feeding device. 2. In a robot body equipped with at least one of a wire feeding device that sends welding wire to a welding torch and a welding torch, the wire drive unit is configured with a piezoelectric element, and the wire drive unit is installed inside the welding torch body. A welding wire feeding device for a welding robot, which is characterized by being equipped with. 3. In a robot body equipped with at least one of a wire feeding device for feeding a welding wire to a welding torch and a welding torch, a pressure roller and a wire contacting part of a laminated piezoelectric element constituting a wire drive part. 1. A welding wire feeding device for a welding robot, characterized in that a welding wire is held between the rollers and a wire guide groove is provided in either the wire contact portion or the pressure roller. 4. A robot body equipped with at least one of a wire feeding device for feeding a welding wire to a welding torch and a welding torch, comprising a pair of wire drive units facing each other with respect to the welding wire, and the wire drive unit A welding wire feeding device for a welding robot, characterized in that a wire is held at a wire contact portion of a laminated piezoelectric element that constitutes a welding robot. 5. The device according to claim 3, comprising a rotation detector for detecting the number of rotations of the pressure roller and a frequency adjuster for controlling the frequency of the voltage applied to the piezoelectric element. The wire feeding speed is maintained at a predetermined speed by controlling the frequency of the voltage applied to the piezoelectric element based on the detection signal, or by keeping the frequency constant and controlling the applied voltage value. Welding wire feeding device for welding robots. 6. In the device described in claim 4, voltages of different frequencies are applied to the pair of wire drive units provided to face each other, or voltages of different voltage values are applied while keeping the frequency constant. 1. A welding wire feeding device for a welding robot, characterized in that a control circuit is configured to impart bending to the feeding wire by applying a voltage to the wire and changing the amount of change in the wire contact portion.