JP6339783B2 - Wire feeder - Google Patents

Description

  The present invention relates to a wire feeding device for feeding a welding wire.

  Conventionally, a welding wire is mechanically short-circuited by repeating advancing (inching) and retreating (retracting) a welding wire with respect to a base material at high speed to realize welding with less spatter. Such a technique is described in Patent Document 1, for example.

  In addition, in the wire feeder which feeds a welding wire, two or more wire feeding mechanisms may be used. When the above inching and retracting are repeated in such a wire feeding device, there is a problem that the welding wire cannot be fed as instructed when the wire feeding in both feeding mechanisms is not synchronized. . For example, in the two wire feeding mechanisms, when torque acts in the direction in which the welding wires are pulled, the torques of the two wire feeding mechanisms cancel each other, and the welding wires may not be fed. . Conversely, if a torque acts in the direction in which the welding wires are pressed against each other, the welding wires may be buckled.

  Therefore, for example, Patent Document 2 describes a wire buffer mechanism that is used to solve the synchronization problem that occurs when two wire feeding mechanisms are used. By providing the wire buffer mechanism between the two wire feeding mechanisms, it is possible to absorb the difference in the welding wire feeding between the two feeding mechanisms. For example, Patent Document 3 describes a method of preventing interference between motors by cutting off a command to the motor of the auxiliary feeding mechanism at the time of retracting. For example, Patent Document 4 describes a method of stably feeding a welding wire by increasing a command torque of a push-side motor in accordance with an increase in a current value of a pull-side motor. Yes.

Special table 2008-542027 gazette Special table 2007-518568 gazette JP 2008-105035 A Japanese Patent Publication No.57-33099

  However, by providing the wire buffer mechanism described in Patent Document 2, there is a problem that the cost of the wire feeding device increases. In addition, the method of Patent Document 3 has a problem in that the motor of the auxiliary feeding mechanism is stopped at the time of retraction, so that it cannot cope with high-speed inching and retraction. Further, in the repetition of high-speed inching and retraction, the torque required for the rotation of the feeding roller changes greatly. Therefore, as in the method of Patent Document 4, the push-side is increased according to the increase in the current value of the pull-side motor. However, there is a problem that it is not possible to cope only by increasing the command torque of the motor.

  The present invention has been made in order to solve the above-described problems. Even when two or more motors are used to feed a welding wire, the present invention can cooperate with each other without canceling the torque of each motor. An object of the present invention is to provide a wire feeding device that can realize inching and retracting.

In order to achieve the above object, a wire feeding device according to the present invention includes a first feeding roller that feeds a welding wire, a first motor that drives the first feeding roller, and a first feeding. A second feed roller that feeds the welding wire on the upstream side of the roller, a second motor that drives the second feed roller, and a motor speed command value that is a speed command value of the first motor. A motor speed command generator to be generated, a speed acquisition unit that acquires the actual speed of the first motor, and a first current that is a current command value of the first motor according to the motor speed command value and the actual speed A first current command generator that generates a command value; a current value acquisition unit that acquires an actual current value of the first motor; and a second current command value that is a current command value of the second motor. A second current command generator, a first mode corresponding to the actual current value and the motor speed command value; And a current command correction unit that corrects the second current command value so that the second motor follows the first motor using the current value of the current value, and according to the first current command value The first motor is driven, and the second motor is driven in accordance with the second current command value corrected by the current command correction unit.
With such a configuration, the second current command value can be corrected so that the second motor follows the first motor. Therefore, the first and second motors supply the welding wire in a coordinated manner. Will do. Moreover, since correction is performed using the actual current value of the first motor and the current value of the first motor corresponding to the motor speed command value, correction using the command and the result corresponding to the command is performed. It becomes possible, and faster tracking is possible.

The wire feeding device according to the present invention further includes a wire speed command generator that generates a wire speed command value that is a speed command value of the welding wire, and the motor speed command generator generates a motor according to the wire speed command value. The speed command value is generated, and the second current command generator may generate the second current command value according to the wire speed command value.
With such a configuration, the first and second motors can be driven using the first and second current command values corresponding to the wire speed command value.

Moreover, in the wire feeding device according to the present invention, the wire speed command generator may generate a wire speed command value in accordance with repetition of forward advancement and retraction of the welding wire.
With such a configuration, the welding wire can be periodically inched and retracted while the two motors are coordinated.

The wire feeder according to the present invention further includes a current value estimating unit that acquires an estimated current value that is a current command value of the first motor estimated from the motor speed command value, and the current command correcting unit includes the motor speed The second current command value may be corrected using an estimated current value that is a current value of the first motor according to the command value.
With such a configuration, an estimated current value estimated from an actual motor speed command value can be used, and correction with high accuracy can be possible. Further, it is possible to cope with the case where the motor speed command value changes depending on the situation.

In the wire feeder according to the present invention, the current command correction unit may correct the second current command value according to the difference between the actual current value and the estimated current value.
With such a configuration, the second current command value can be corrected in real time, and the followability of the second motor to the first motor can be improved.

In the wire feeder according to the present invention, the second current command generator periodically outputs a current value pattern which is a pattern of one cycle of a predetermined current value, The correction unit may perform correction related to at least one of the amplitude of the current value pattern and the offset of the current value.
With such a configuration, correction can be performed in units of current value patterns, and stable control is possible. As a result, it is possible to prevent the welding wire feeding from becoming unstable due to the correction of the second current command value.

  According to the wire feeding device of the present invention, even when two or more motors are used to feed the welding wire, the feeding wire feeding by each motor does not compete and high-speed inching is performed in a coordinated manner. Retract can be realized.

The block diagram which shows the structure of the wire feeding apparatus by embodiment of this invention. The figure which shows the feed mechanism of the welding wire in the embodiment The flowchart which shows an example of operation | movement of the wire feeder by the same embodiment The figure which shows an example of relations, such as command value and current value in the embodiment The flowchart which shows an example of operation | movement of the wire feeder by the same embodiment

  Hereinafter, a wire feeding device according to the present invention will be described using embodiments. In the following embodiments, components and steps denoted by the same reference numerals are the same or equivalent, and repetitive description may be omitted.

  A wire feeding device according to an embodiment of the present invention will be described with reference to the drawings. The wire feeding device 1 according to the present embodiment feeds a welding wire by two motors so that the front side (push side) motor follows the rear side (pull side) motor. It corrects the current command value of the motor on the front side.

  FIG. 1 is a block diagram showing a configuration of a wire feeding device 1 according to the present embodiment. FIG. 2 is a view for explaining a feeding mechanism of the welding wire 5 in the wire feeding device 1. The wire feeding device 1 according to the present embodiment includes a first feeding roller 6a, a second feeding roller 7a, a first motor 11, a second motor 12, and a current value acquisition unit 13. A speed acquisition unit 14, a wire speed command generator 15, a motor speed command generator 16, a first current command generator 17, a current value estimation unit 18, a second current command generator 19, A current command correction unit 20. The feeding of the welding wire 5 by the wire feeding device 1 may be, for example, feeding of the welding wire 5 in a welding robot or feeding of the welding wire 5 in other devices.

  As shown in FIG. 2, the welding wire 5 wound around the wire reel 2 is fed to the welding torch 3 by the second feeding roller 7a and the first feeding roller 6a. The welding wire 5 passes through the conduit cable 9 between the first feeding roller 6a and the second feeding roller 7a. The first feeding roller 6a and the second feeding roller 7a are respectively a first pressure roller 6b for urging the welding wire 5 toward the first feeding roller 6a and the second feeding roller 7a, and It faces the second pressure roller 7b. The first and second feeding rollers 6a and 7a feed the welding wire 5 by cooperating with the first and second pressure rollers 6b and 7b, respectively. That is, the first and second motors 11 and 12 respectively feed the welding wire 5 according to inching and retracting. The second feeding roller 7a and the second pressure roller 7b feed with the welding wire 5 sandwiched between the first feeding roller 6a and the first pressure roller 6b. Here, the pre-stage side means an upstream side in feeding the welding wire 5 and is a side close to the wire reel 2. Therefore, the first feeding roller 6a is a welding-side feeding roller (pull-side feeding roller), and the second feeding roller 7a is a feeding-side feeding roller (push-side feeding roller). ).

  The first motor 11 drives the first feeding roller 6a, and the second motor 12 drives the second feeding roller 7a. The first and second motors 11 and 12 can drive the first and second feeding rollers 6a and 7a in the direction in which the welding wire 5 is advanced and the direction in which the welding wire 5 is moved backward, respectively. Here, the direction in which the welding wire 5 moves forward is the direction in which the welding wire 5 moves toward the welding torch 3, and the direction in which the welding wire 5 moves backward refers to the direction in which the welding wire 5 moves toward the wire reel 2. It is. Moreover, the method by which a rotational force is transmitted from the 1st and 2nd motors 11 and 12 with respect to the 1st and 2nd feed rollers 6a and 7a does not ask | require. For example, a reduction gear or the like may exist between the two.

  The current value acquisition unit 13 acquires the actual current value of the first motor 11. The current value acquisition unit 13 may be, for example, a current detector that detects a current flowing through the first motor 11. Further, the current value acquisition unit 13 may receive the actual current value of the first motor 11 from, for example, a current detector (not shown) that acquires the actual current value of the first motor 11. The acquired actual current value may be stored in a recording medium (not shown). Further, the current value acquisition unit 13 passes the acquired actual current value to the current command correction unit 20.

  The speed acquisition unit 14 acquires the actual speed of the first motor 11. The actual speed is usually an angular speed. The method by which the speed acquisition unit 14 acquires the actual speed of the first motor 11 does not matter. For example, the speed acquisition unit 14 may include an encoder that measures the angle of the first motor 11, and may measure the actual speed of the first motor 11 by differentiating the angle of the encoder with respect to time. Further, the speed acquisition unit 14 acquires the angle of the first motor 11 from the encoder of the first motor 11 and measures the actual speed of the first motor 11 by time-differentiating the angle, for example. Good. Further, the speed acquisition unit 14 may receive the actual speed of the first motor 11 from, for example, a speed measurement unit (not shown) that acquires the angular speed of the first motor 11. The acquired actual speed may be stored in a recording medium (not shown). The speed acquisition unit 14 passes the acquired actual speed to the first current command generator 17.

  The wire speed command generator 15 generates a wire speed command value that is a speed command value of the welding wire 5. The wire speed command value may be, for example, a predetermined command or a command calculated according to actual feeding of the welding wire 5 (for example, a command determined by feedback control or the like). Good. Therefore, in the former case, the wire speed command generator 15 may read and output a predetermined command. In that case, the wire speed command generator 15 may generate a wire speed command value corresponding to the repeated forward and backward movements of the welding wire 5. The wire speed command value is a speed command value in which a unit period having a period in which the speed of the welding wire 5 from the welding torch 3 toward the base material is a positive value and a period in which the speed is a negative value is repeated. There may be. The period is usually constant. The wire speed command value is passed to the motor speed command generator 16 and the second current command generator 19.

  The motor speed command generator 16 generates a motor speed command value that is a speed command value of the first motor 11 in accordance with the wire speed command value generated by the wire speed command generator 15. Since the wire speed command value is a command value of the speed of the welding wire 5, the motor speed command generator 16 has the radius of the first feed roller 6a, the first motor 11 and the first feed roller 6a. The speed of the welding wire 5 is converted into the speed of the first motor 11 in consideration of the reduction ratio of the reduction gear existing between the two. Normally, the motor speed command value can be generated by multiplying the wire speed command value by a constant. The motor speed command is passed to the first current command generator 17 and the current value estimation unit 18.

  The first current command generator 17 generates a first current command value that is a current command value of the first motor 11 according to the motor speed command value and the actual speed. The first current command value is generated so that the actual speed approaches the motor speed command value. This feedback control is a normal speed loop in motor control, and detailed description thereof is omitted. Further, the first motor 11 is driven according to the first current command value. That is, the current indicated by the first current command value is controlled to flow to the first motor 11. Therefore, the first current command value that is the output of the first current command generator 17 is input to a torque command generator (not shown), and the torque command generator has the actual current value of the first motor 11 as The torque of the first motor 11 may be controlled so as to approach the first current command value. The actual current value may be acquired by the current value acquisition unit 13. Such torque control of the motor according to the current command value is already known, and detailed description thereof is omitted.

  The current value estimation unit 18 acquires an estimated current value that is a current command value of the first motor 11 estimated from the motor speed command value generated by the motor speed command generator 16. This estimated current value is a current value of the first motor 11 corresponding to the motor speed command value. That is, an ideal current value corresponding to the motor speed command value is the estimated current value. Therefore, if the estimated current value is passed through the first motor 11, the first motor 11 rotates at the speed of the motor speed command value. A method for obtaining the estimated current value will be described later. The estimated current value is passed to the current command correction unit 20.

  The second current command generator 19 generates a second current command value that is a current command value of the second motor 12 in accordance with the wire speed command value generated by the wire speed command generator 15. The second current command value generated in accordance with the wire speed command value is similar to the first current command value, and the motor speed command value generated by the wire speed command value and the second motor 12 It may be a current command value generated using the actual speed. In that case, the second current command generator 19 generates a motor speed command value of the second motor 12 from the wire speed command value, a motor speed command value generated by the generation unit, You may have the production | generation means which produces | generates a 2nd electric current command value using the actual speed of the 2nd motor 12. FIG. These processes are the same processes as the motor speed command generator 16 and the first current command generator 17. When the actual speed of the second motor 12 is used for generating the second current command value, the wire feeding device 1 has a speed acquisition unit that acquires the actual speed of the second motor 12. May be. In the present embodiment, the second current command generator 19 generates a motor speed command value using the wire speed command value, and uses the motor speed command value and the actual speed of the second motor 12 to The case where 2 current command values are generated will be mainly described.

  The current command correction unit 20 uses the actual current value and the current value of the first motor 11 corresponding to the motor speed command value so that the second motor 12 follows the first motor 11. Correct the current command value of 2. In the present embodiment, the current command correction unit 20 uses the estimated current value acquired by the current value estimation unit 18 as the current value of the first motor 11 corresponding to the motor speed command value. The case of correcting the value will be mainly described. By performing this correction, the second motor 12 follows the first motor 11, and the first and second motors 11 and 12 are driven in cooperation. This correction may be to change the second current command value output from the second current command generator 19, and the second current command value is output so as to output the corrected second current command value. The current command generator 19 may be controlled. In the former case, the second current command value before correction is output, but in the latter case, the second current command value before correction is not output. Moreover, the current command correction unit 20 may correct the second current command value according to the difference between the actual current value and the estimated current value, for example. That is, the current command correction unit 20 determines that the difference between the actual current value and the estimated current value is zero or the ratio between the two according to the ratio between the actual current value and the estimated current value. The second current command value may be modified so that becomes 1: 1. Further, the correction of the second current command value according to the difference between the actual current value and the estimated current value may be performed as a real-time process. A method for correcting the second current command value in real time will be described later.

  The second motor 12 is driven in accordance with the second current command value corrected by the current command correction unit 20. In other words, the current indicated by the second current command value is controlled to flow to the second motor 12. This control method is the same as the control method in which the first motor 11 is driven in accordance with the first current command value, and the description thereof is omitted. For this control, the wire feeding device 1 uses a torque command generator (not shown) that controls the torque of the second motor 12 according to the second current command value, or the actual current value of the second motor 12. A current value acquisition unit (not shown) that acquires

[Method of obtaining estimated current value]
A method for obtaining the estimated current value by the current value estimating unit 18 will be described. First, the relationship between the torque τ _{p, k} at the time k of the first motor 11, the estimated current value i _{i, k at} the time _k , and the torque constant K _p of the first motor 11 is as follows: Become.
τ _{p, k} = i _{i, k} · K _p
Further, the motor shaft conversion inertia of the first motor 11 and J _p, when the motor speed value at time k of the first motor 11 and omega _k, the relationship between them and the torque tau _{p, k,} the following equation become that way. Note that Δt is the difference between time k and time k−1.
τ _{p, k} = J _p · (ω _k −ω _k−1 ) / Δt

Therefore, assuming that K _T = K _p · Δt, the current value estimation unit 18 uses the estimated current value i _{i, k} at time k as the motor speed command value ω _{k at} time k, k−1 as shown in the following equation. , and omega _k-1, can be calculated using the inertia _{J p,} and _{K T.} In order to calculate the following equation, the current value estimation unit 18 may store at least the latest two ω _k and ω _k−1 of the speed command values in a recording medium (not shown). Further, the current value estimation unit 18 may read J _p / K _T stored in a recording medium (not shown) and use it for calculating the following equation.
_{i i, k = J p ·} (ω k -ω k-1) / K T

[Second Current Command Value Correction Method]
A method for correcting the second current command value by the current command correcting unit 20 will be described. First, the actual current value of the first motor 11 is i _p , the torque constant is K _p , the torque is τ _p , the radius of the first feeding roller 6 a is r _p , and the first feeding from the first motor 11 is performed. When the speed ratio (reciprocal of the reduction ratio) to the roller 6a is g _p and the force applied to the welding wire 5 according to the torque τ _p is F _p , the following expression is obtained.
i _p · K _p = τ _p = r _p · F _p / g _p

The actual current value of the second motor 12 is i _q , the torque constant is K _q , the torque is τ _q , the radius of the second feed roller 7 a is r _q , and the second feed from the second motor 12 is second feed. When the speed ratio to the roller 7a is g _q and the force applied to the welding wire 5 according to the torque τ _q is F _q , the following equation is obtained.
i _q · K _q = τ _q = r _q · F _q / g _q
Here, when the above two equations are used as F _p = F _q , the following equation is obtained.
i _q = i _p · K _p g _p r _q / K _{q q} g _q r _p

Therefore, in order to be generating a longitudinal force of the welding wire 5 according to the actual current i _p of the first motor 11 in the second motor 12, actual current i _q of the second motor 12, It can be seen that i _p · K _p g _p r _q / K _q g _{q q} r _p is sufficient. Therefore, the current command correction unit 20, the second electric current command value i _c, by modifying the following equation may acquire the second current command value i _m of the corrected.
_{i m = α (i a -i} i) · K p g p r q / K q g q r p + i c
Here, α is a correction gain, i _a is an actual current value acquired by the current value acquisition unit 13, and i _i is an estimated current value acquired by the current value estimation unit 18. Note that “i _a -i _i ” is the current value of the first motor 11 that is not sufficient for the motor speed command value. Then, those obtained by converting the current value to the second motor _12, the _{(i a -i i) · K} p g p r q / K q g q r p. Of these, since the product multiplied by the correction gain α is supported on the second motor 12 side, α is usually a positive real number less than 1. The correction gain α may be appropriately determined by, for example, an operator or a designer of the wire feeding device 1.

Further, the above formula is an example, and for example, the current command correction unit 20 may correct the second current command value _ic as in the following formula. Β is a positive coefficient that is set as appropriate so that the second motor 12 can provide support according to the difference between the actual current value and the estimated current value of the first motor 11.
_{i m = i c (1 +} β (i a -i i))

  Next, operation | movement of the wire feeder 1 is demonstrated using the flowchart of FIG. In this flowchart, the acquisition of the actual current value by the current value acquisition unit 13 and the acquisition of the actual speed by the speed acquisition unit 14 are not particularly specified, but are performed respectively. It is also assumed that the actual speed and actual current value of the second motor 12 have been acquired.

  (Step S101) The wire speed command generator 15 determines whether or not to generate a wire speed command value. If the wire speed command value is to be generated, the process proceeds to step S102. If not, the process of step S101 is repeated until it is determined that the wire speed command value is to be generated. Note that the wire speed command generator 15 may periodically determine to generate a wire speed command value, for example.

  (Step S102) The wire speed command generator 15 generates a wire speed command value. The generated wire speed command value may be stored in a recording medium (not shown).

  (Step S103) The motor speed command generator 16 generates a motor speed command value according to the generated wire speed command value. The generated motor speed command value may be stored in a recording medium (not shown).

  (Step S104) The first current command generator 17 generates a first current command value using the motor speed command value and the actual speed acquired by the speed acquisition unit 14. The generated first current command value may be stored in a recording medium (not shown). In accordance with the first current command value, the first motor 11 drives the first feeding roller 6a.

  (Step S105) The current value estimation unit 18 acquires an estimated current value according to the motor speed command value. Strictly speaking, the estimated current value is calculated according to the time change (time differentiation) of the motor speed command value. The acquired estimated current value may be stored in a recording medium (not shown).

  (Step S106) The second current command generator 19 generates a motor speed command value for the second motor 12 in accordance with the generated wire speed command value, and the motor speed command value for the second motor 12 Then, the second current command value is generated using the actual speed of the second motor 12. The generated second current command value may be stored in a recording medium (not shown).

(Step S107) The current command correction unit 20 corrects the second current command value using the estimated current value and the actual current value. Processing of the modification, for example, may be a modified using the above equations for i _m. The corrected second current command value may be stored in a recording medium (not shown). The second motor 12 drives the second feeding roller 7a in accordance with the corrected second current command value. Then, the process returns to step S101.

  The process of acquiring the estimated current value in step S105 is performed after the process of generating the motor speed command value (step S103) and before the process of correcting the second current command value (step S107). If it is, the timing does not matter. Further, in the flowchart of FIG. 3, in place of steps S106 and S107, the second current command generator 19 generates a corrected second current command value according to the correction control by the current command correction unit 20. May be provided. Further, in the flowchart of FIG. 3, the process is ended by powering off or interruption for aborting the process.

  As described above, according to the wire feeding device 1 according to the present embodiment, the first and second current command values are corrected so that the second motor 12 follows the first motor 11. Both the motors 11 and 12 feed the welding wire 5 in a coordinated manner without the competition of the feeding of the welding wire 5 by the second motors 11 and 12. Moreover, since the correction is performed using the actual current value and the estimated current value, the welding wire 5 can be moved forward and backward at high speed. That is, since the correction is performed also using the command value (estimated current value), higher followability can be obtained than when only the actual current value is used. In addition, the current command correction unit 20 corrects the second current command value in real time according to the difference between the actual current value and the estimated current value, so that the second motor 12 is changed to the first motor 11 at high speed. Can be made to follow.

  Note that the method by which the second current command generator 19 generates the second current command value is not limited to the above. For example, as described in Patent Document 4, the second current command generator 19 uses the torque of the first motor 11 and the torque of the second motor 12 to generate the torque of the second motor 12. A second current command value for approaching the torque of the first motor 11 may be generated. Further, the second current command generator 19 may generate a second current command value for driving the second motor 12 with a constant torque.

  In the present embodiment, the case where the current command correction unit 20 corrects the second current command value according to the difference between the actual current value and the estimated current value has been described, but this need not be the case. . When the second current command value is a repetition of a predetermined pattern, the current command correction unit 20 determines the second current command value according to the difference between the actual current value and the estimated current value in pattern units. The pattern may be modified. In such a case, for example, the wire speed command value generated by the wire speed command generator 15 may be periodic in which the welding wire 5 is repeatedly advanced and retracted. In addition, the second current command generator 19 may periodically output a current value pattern that is a pattern of one cycle of a predetermined current value. This period may be the same as the unit period described above. For example, the second current command generator 19 may read the current value pattern and output it periodically even if stored in a recording medium (not shown). In addition, when the wire speed command value generated by the wire speed command generator 15 is a command value corresponding to repeated forward and backward movements of the welding wire 5, the second current command generator 19 The wire speed command value may be used to output a current value pattern so as to be synchronized with the wire speed command value. Therefore, when the second current command generator 19 generates the second current command value according to the wire speed command value, the second current command generator 19 is synchronized with the wire speed command value. The current value pattern that is the current command value of 2 may be output periodically.

  When the second current command generator 19 generates the second current command value by periodically outputting the current value pattern and outputting the current value pattern, the current command correction unit 20 determines the amplitude of the current value pattern. , And at least one of current value offsets may be corrected. In that case, the current command correction unit 20 corrects the second current command value in units of current value patterns.

Such correction of the second current command value will be specifically described with reference to the waveform of FIG. The motor speed command value generated by the motor speed command generator 16 in accordance with the periodic wire speed command value generated by the wire speed command generator 15 is, for example, as shown in FIG. In FIG. 4A, the period is t _P , and for example, time t _{0 to} t ₀ + t _P is one period (unit period). In addition, the frequency according to the period may be 1 Hz to 150 Hz, for example, and may be other frequencies. The frequency may be 50 Hz to 130 Hz. When the motor speed command value is shown in FIG. 4A, for example, the estimated current value acquired by the current value estimation unit 18 is shown by a broken line in FIG. 4B. Since the motor speed command value has the same pattern for each cycle, the estimated current value also has the same pattern for each cycle. On the other hand, the actual current value acquired by the current value acquiring unit 13 can be different from the estimated current value (ideal current value) as shown by the solid line in FIG. For example, in the period from the time t ₀ ~t _{0 +} t _P, the actual current value, the amplitude is larger than the estimated current value. In addition, during the period from time t ₀ + t _{P to} t ₀ + 2t _P , the actual current value is shifted to the larger current value as a whole than the estimated current value.

When the wire speed command value generated by the wire speed command generator 15 is periodic, the second current command generator 19 is a second current command value according to the wire speed command value. A current value pattern may be generated. The generation of the current value pattern may be to output a current value pattern in synchronization with the wire speed command value as described above. For example, in the wire speed command value, the second current command generator 19 may start outputting the current value pattern at a timing at which the speed command value changes from negative to positive. The power value pattern output in this way is as shown by the broken line in FIG. Then, the current command correction unit 20 may correct the amplitude or offset of one cycle of the second current command value that is a repetition of the current value pattern. Specifically, as shown in the period between time t ₀ ~t _{0 +} t _P in FIG. 4 (b), when the amplitude of the pattern of the actual current value is greater than the amplitude of the pattern of the estimated current value, The current command correction unit 20 has a reference current command in which the amplitude of the second current command value after the correction from time t ₀ + t _{P to} t ₀ + 2t _P shown by the solid line in FIG. It may be made larger than the amplitude of the value (current value pattern). Therefore, for example, the current command correction unit 20 may multiply the second current command value output from the second current command generator 19 by an amplitude coefficient, or outputs a pattern obtained by multiplying the current value pattern by the amplitude coefficient. As described above, the second current command generator 19 may be controlled. Further, as shown in the period from time t ₀ + t _{P to} t ₀ + 2t _P in FIG. 4B, the actual current value pattern is shifted to the larger current value with respect to the estimated current value pattern. In this case, the current command correction unit 20 indicates that the second current command value after the correction at the time t ₀ + 2t _{P to} t ₀ + 3t _P indicated by the solid line in FIG. You may make it have an offset in the one where a current value is larger than a current command value. Therefore, for example, the current command correction unit 20 may add an offset value to the second current command value output from the second current command generator 19, or a pattern obtained by adding the offset value to the current value pattern. The second current command generator 19 may be controlled to output. Note that, as described above, the current command correction unit 20 compares the actual current value with the estimated current value in the period (unit period) from time t ₀ + n × t _{P to} t ₀ + (n + 1) × t _P. According to the result, the pattern of the second current command value in the period from time t ₀ + (n + 1) × t _{P to} t ₀ + (n + 2) × t _P is corrected. n is an arbitrary integer. The correction may be correction related to the amplitude of the current value pattern, correction related to the offset of the current value of the current value pattern, or correction of both. When correcting the amplitude of the current value pattern, the current command correcting unit 20 may calculate an amplitude coefficient to be multiplied by the amplitude of the current value pattern. Further, in the case of performing correction related to the offset of the current value pattern, the current command correction unit 20 may calculate an offset value to be added to the current value pattern. Then, the current command correction unit 20 may correct the current value pattern using the calculated amplitude coefficient and offset value.

A specific process in which the current command correction unit 20 calculates such an amplitude coefficient and offset value will be described. When the current command correction unit 20 receives the actual current value and the estimated current value in the period from time t ₀ + n × t _{P to} t ₀ + (n + 1) × t _P , the average of the actual current values in the one period And the average of the estimated current values. Then, the current command correction unit 20 determines that: | average of actual current value−average of estimated current value | <ε1
Offset value = 0
When | average of actual current value−average of estimated current value | ≧ ε1,
Offset value = alpha (average of the actual current value - average of the estimated current _{value) · K p g p r q} / K q g q r p
May be set. Note that α, K _p , g _p , r _p , K _q , g _q , and r _q are the same as described above. Also, ε1 is a positive value, and is a value that is so small that the average of both current values can be identified when | average of actual current value−average of estimated current value | <ε1. Then, the current command correction unit 20 calculates the offset value calculated as the second current command value (current value pattern) in the period from time t ₀ + (n + 1) × t _{P to} t ₀ + (n + 2) × t _P. Is added.

In addition, the current command correction unit 20 is configured to calculate the maximum value of the actual current value of the period from time t ₀ + n × t _{P to} t ₀ + (n + 1) × t _P− (average of actual current value−average of estimated current value) and The minimum value (which will be referred to as the actual maximum value and the actual minimum value) is compared with the maximum value and minimum value of the estimated current value (which will be referred to as the estimated maximum value and the estimated minimum value). Then, the current command correction unit 20 determines that (1−ε2) <| actual maximum value / estimated maximum value | <(1 + ε2) or (1−ε2) <| actual minimum value / estimated minimum value | < If (1 + ε2),
Amplitude coefficient = 1
If | actual maximum value / estimated maximum value | ≦ (1-ε2) and | actual minimum value / estimated minimum value | ≦ (1-ε2), or (1 + ε2) ≦ | actual maximum value / If the estimated maximum value | and (1 + ε2) ≦ | actual minimum value / estimated minimum value |
Amplitude coefficient = γ (| actual maximum value / estimated maximum value | + | actual minimum value / estimated minimum value |) / 2
May be set. Normally, | real maximum value / estimated maximum value | ≦ (1-ε2) and (1 + ε2) ≦ | actual minimum value / estimated minimum value |, or | actual minimum value / estimated minimum value | ≦ (1- It is considered that ε2) and (1 + ε2) ≦ | actual maximum value / estimated maximum value |. However, if there is such a case, amplitude coefficient = 1 may be set. Also, ε2 is a positive value, and (1−ε2) <| actual maximum value / estimated maximum value | <(1 + ε2) or (1−ε2) <| actual minimum value / estimated minimum value | <(1 + ε2) In this case, the actual maximum value and the estimated maximum value, or the actual minimum value and the estimated minimum value are so small that they can be identified. Further, γ is a positive value that is set as appropriate so that the second motor 12 can provide support according to the difference between the amplitude of the actual current value of the first motor 11 and the amplitude of the estimated current value. It is a coefficient. Usually, γ is a value close to 1.

  Although an example of calculating the offset value and the amplitude coefficient has been described here, the offset value and the amplitude coefficient may be calculated by other methods. Further, the current command correction unit 20 may correct other than the offset and amplitude of the current value pattern. For example, the current command correction unit 20 compares the time within one cycle when the actual current value becomes the maximum value or the minimum value with the time within one cycle when the estimated current value becomes the maximum value or the minimum value. You may adjust the output timing of a current value pattern so that it may correspond. That is, the current value pattern may be moved in the time direction.

It is preferable that the current command correction unit 20 appropriately connects the corrected second current command value at the boundary of each unit period. This is to prevent a gap from occurring in the corrected second current command value.
FIG. 4 is provided for convenience of explanation, and the relationship between the motor speed command value and the estimated current value corresponding to the motor speed command value is not necessarily accurate.

  FIG. 5 is a flowchart showing the operation of the wire feeding device 1 when the second current command generator 19 outputs a current value pattern and the current command correction unit 20 corrects the amplitude or the like of the current value pattern. . Note that the processing in steps S101 to S105 is the same as that in the flowchart of FIG.

  (Step S201) The current command correction unit 20 stores the estimated current value acquired by the current value estimation unit 18 and the actual current value at that time in a recording medium (not shown). At the time of the accumulation, the current command correction unit 20 may accumulate in association with the time at that time.

  (Step S202) The second current command generator 19 generates a second current command value. This generation may be performed by reading and outputting a value at a time corresponding to the current time from a current value pattern stored in a recording medium (not shown) in advance.

(Step S203) The current command correction unit 20 corrects the second current command value output from the second current command generator 19 by using the offset value or amplitude coefficient set at that time. Specifically, the second current command value may be corrected as in the following equation.
Second current command value after correction = amplitude coefficient × second current command value before correction + offset value

(Step S204) The current command correction unit 20 determines whether it is time to calculate an offset value or the like. If it is the timing, the process proceeds to step S205. If not, the process returns to step S101. Note that the current command correction unit 20 determines that it is time to calculate an offset value or the like at the time when the unit period ends (in the above description, the time becomes t ₀ + n × t _P ). Good.

  (Step S205) The current command correction unit 20 calculates the offset value as described above, for example, using the actual current value and the estimated current value in the latest unit period. This calculated offset value may be stored in a recording medium (not shown).

  (Step S206) The current command correction unit 20 calculates the amplitude coefficient as described above, for example, using the actual current value and the estimated current value in the latest unit period. This calculated amplitude coefficient may be stored in a recording medium (not shown). Then, the process returns to step S101. In the correction of the second current command value in the subsequent unit period, correction using the calculated offset value and amplitude coefficient is performed.

  Also in the flowchart of FIG. 5, instead of steps S202 and S203, the second current command generator 19 generates a corrected second current command value in accordance with the correction control by the current command correction unit 20. Steps may be provided. Further, in the flowchart of FIG. 5, the processing is ended by powering off or interruption of processing end.

  As described above, the current command correcting unit 20 corrects the offset and amplitude of the current value pattern, thereby enabling stable control. That is, when feedback control is performed using the corrected second current command value, the possibility of vibration and divergence can be reduced. In addition, since the correction by the current command correction unit 20 is limited to a change in offset, amplitude, etc., it is possible to include both the forward period and the reverse period in one cycle by providing a restriction on the offset amount. , Inching and retract can be realized properly. The advance period is a period in which the welding wire 5 advances, and the retreat period is a period in which the welding wire 5 moves backward. In addition, when the correction according to the pattern is performed as described above, the current value is corrected for each cycle, and therefore, the current command value for each cycle is sent in a feedforward manner. Therefore, the synchronization performance is improved.

In the description with reference to FIG. 4, although the period of such time t ₀ ~t _{0 +} t _P is to be one period or not. For example, the duration of time _t 0 _~t 0 + 2t _P may be one cycle. That is, one set or more of forward and backward may be repeated in one cycle.

  Moreover, although the case where the wire feeding device 1 has two feeding mechanisms has been described in the present embodiment, the wire feeding device 1 may have three or more feeding mechanisms. In that case, for example, the current command values of two or more motors in the preceding stage may be corrected using the actual current value and the estimated current value relating to the last stage motor, respectively. Or, for example, the current of the motor immediately preceding the first motor (referred to as the second motor) using the actual current value related to the last motor (referred to as the first motor) and the estimated current value. The command value is corrected, and the current command value of the immediately preceding motor of the second motor is corrected using the actual current value related to the second motor and the estimated current value. It may be repeated up to the motor.

  Moreover, although this Embodiment demonstrated the case where the wire feeder 1 was provided with the electric current value estimation part 18, it may not be so. When the estimated current value is not acquired, the wire feeding device 1 may not include the current value estimating unit 18. When the current value estimating unit 18 is not provided, the current command correcting unit 20 uses the current value of the first motor 11 corresponding to the motor speed command value instead of the estimated current value to set the second current command value. Corrections may be made. For example, as shown in FIG. 4, when the motor speed command value is a periodic command value, the current value of the first motor 11 corresponding to the motor speed command value corresponding to the one cycle (that is, (The estimated current value for one cycle) is stored in a recording medium (not shown), and the current command correction unit 20 is the current of the first motor 11 corresponding to the motor speed command value that is the stored current value. The second current command value may be corrected using the value and the actual current value.

  Moreover, although the case where the wire feeding device 1 includes the wire speed command generator 15 has been described in the present embodiment, this need not be the case. When the generation of the wire speed command is not performed, the wire feeding device 1 may not include the wire speed command generator 15. When the wire speed command generator 15 is not provided, the motor speed command generator 16 holds a periodic motor speed command as shown in FIG. 4A in advance, for example. You may output repeatedly. Further, as described above, the second current command generator 19 may output the current value pattern repeatedly. The motor speed command generator 16 and the second current command generator 19 are configured to output while matching their timing so that the motor speed command value and the second current command value are synchronized. Also good.

  In the above embodiment, each process or each function may be realized by centralized processing by a single device or a single system, or may be distributedly processed by a plurality of devices or a plurality of systems. It may be realized by doing.

  In the above embodiment, the information exchange between the components is performed by one component when, for example, the two components that exchange the information are physically different from each other. It may be performed by outputting information and receiving information by the other component, or when two components that exchange information are physically the same, one component May be performed by moving from the phase of the process corresponding to to the phase of the process corresponding to the other component.

  In the above embodiment, information related to processing executed by each component, for example, information received, acquired, selected, generated, transmitted, or received by each component In addition, information such as threshold values, mathematical formulas, setting values, etc. used by each component in the processing is temporarily or over a long period of time on a recording medium (not shown), even if not specified in the above description. Also good. Further, the storage of information in the recording medium (not shown) may be performed by each component or a storage unit (not shown). Further, reading of information from the recording medium (not shown) may be performed by each component or a reading unit (not shown).

  In the above embodiment, when information used by each component, for example, information such as a threshold value, a mathematical expression, and various setting values used by each component may be changed by the user Even if not specified in the above description, the user may be able to change the information as appropriate, or may not be so. If the information can be changed by the user, the change is realized by, for example, a not-shown receiving unit that receives a change instruction from the user and a changing unit (not shown) that changes the information in accordance with the change instruction. May be. The change instruction received by the receiving unit (not shown) may be received from an input device, information received via a communication line, or information read from a predetermined recording medium, for example. .

  In the above embodiment, each component may be configured by dedicated hardware, or a component that can be realized by software may be realized by executing a program. For example, each component can be realized by a program execution unit such as a CPU reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory. At the time of execution, the program execution unit may execute the program while accessing the storage unit or the recording medium. The program may be executed by being downloaded from a server or the like, or may be executed by reading a program recorded on a predetermined recording medium (for example, an optical disk, a magnetic disk, a semiconductor memory, or the like). Good. Further, this program may be used as a program constituting a program product. Further, the computer that executes the program may be singular or plural. That is, centralized processing may be performed, or distributed processing may be performed.

  Further, the present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these are also included in the scope of the present invention.

  As described above, according to the wire feeding device according to the present invention, even when the welding wire is fed using two or more motors, high-speed inching is achieved in cooperation without canceling the torque of each motor. The effect that the retract can be realized is obtained, and it is useful as a device for feeding the welding wire.

DESCRIPTION OF SYMBOLS 1 Wire feeder 5 Welding wire 6a 1st feed roller 6b 1st pressure roller 7a 2nd feed roller 7b 2nd pressure roller 11 1st motor 12 2nd motor 13 Current value acquisition Unit 14 speed acquisition unit 15 wire speed command generator 16 motor speed command generator 17 first current command generator 18 current value estimation unit 19 second current command generator 20 current command correction unit

Claims (4)

A first feed roller for feeding a welding wire;
A first motor for driving the first feeding roller;
A second feeding roller that feeds the welding wire on the front side of the first feeding roller;
A second motor for driving the second feeding roller;
A wire speed command generator for generating a wire speed command value which is a speed command value of the welding wire;
A motor speed command generator that generates a motor speed command value that is a speed command value of the first motor in accordance with the wire speed command value;
A speed acquisition unit for acquiring an actual speed of the first motor;
A first current command generator that generates a first current command value that is a current command value of the first motor according to the motor speed command value and the actual speed;
A current value acquisition unit for acquiring an actual current value of the first motor;
A second current command generator that generates a second current command value that is a current command value of the second motor according to the wire speed command value;
Using the actual current value and the current value of the first motor according to the motor speed command value, the second current command value so that the second motor follows the first motor. A current command correction unit for correcting
The wire speed command generator generates a wire speed command value corresponding to repetition of periodic advancement and retraction of the welding wire,
The first motor is driven in accordance with the first current command value;
The second current command generator outputs a current value pattern that is a pattern of one cycle of a predetermined current value periodically and outputs,
In the current command correction unit, an absolute value of a difference between an average of the actual current values in a certain cycle and an average of the current values of the first motor according to the motor speed command value is equal to or greater than a first threshold value. If the current value offset of the current pattern of the next period is corrected,
The first threshold is a positive value;
A wire feeding device in which the second motor is driven in accordance with a second current command value corrected by the current command correction unit. The current command correction unit is configured to subtract the average of the actual current values from the actual current value and add the average of the current values of the first motor according to the motor speed command value in a certain cycle. An actual maximum value and an actual minimum value that are values and a minimum value, and an estimated maximum value and an estimated minimum value that are the maximum value and the minimum value of the current value of the first motor according to the motor speed command value in the cycle. When the ratio between the actual maximum value and the estimated maximum value and the ratio between the actual minimum value and the estimated minimum value are both smaller than 1 by a second threshold or larger than 1, the ratio is larger than the second threshold. , Modify the amplitude of the current pattern of the next cycle,
The wire feeding device according to claim 1, wherein the second threshold value is a positive value. A first feed roller for feeding a welding wire;
A first motor for driving the first feeding roller;
A second feeding roller that feeds the welding wire on the front side of the first feeding roller;
A second motor for driving the second feeding roller;
A wire speed command generator for generating a wire speed command value which is a speed command value of the welding wire;
A motor speed command generator that generates a motor speed command value that is a speed command value of the first motor in accordance with the wire speed command value;
A speed acquisition unit for acquiring an actual speed of the first motor;
A first current command generator that generates a first current command value that is a current command value of the first motor according to the motor speed command value and the actual speed;
A current value acquisition unit for acquiring an actual current value of the first motor;
A second current command generator that generates a second current command value that is a current command value of the second motor according to the wire speed command value;
Using the actual current value and the current value of the first motor according to the motor speed command value, the second current command value so that the second motor follows the first motor. A current command correction unit for correcting
The wire speed command generator generates a wire speed command value corresponding to repetition of periodic advancement and retraction of the welding wire,
The first motor is driven in accordance with the first current command value;
The second current command generator outputs a current value pattern that is a pattern of one cycle of a predetermined current value periodically and outputs,
The current command correction unit is configured to subtract the average of the actual current values from the actual current value and add the average of the current values of the first motor according to the motor speed command value in a certain cycle. An actual maximum value and an actual minimum value that are values and a minimum value, and an estimated maximum value and an estimated minimum value that are the maximum value and the minimum value of the current value of the first motor according to the motor speed command value in the cycle. When the ratio between the actual maximum value and the estimated maximum value and the ratio between the actual minimum value and the estimated minimum value are both smaller than 1 or more than the threshold or larger than 1 than the threshold, the current of the next period Make corrections regarding the amplitude of the value pattern,
The threshold is a positive value,
A wire feeding device in which the second motor is driven in accordance with a second current command value corrected by the current command correction unit. A current value estimating unit that obtains an estimated current value that is a current command value of the first motor estimated from the motor speed command value;
The current command correction unit corrects the second current command value by using the estimated current value is a current value of said first motor in accordance with the motor speed command value, claims 1 to 3 The wire feeding device according to any one of the above.

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