JP7637576B2 - Wire feeding system and wire feeding method - Google Patents

Description

The present invention relates to a wire feeding system and a wire feeding method.

When arc welding is performed, slag is generated and may adhere to the end of the welding wire or the base material. If slag adheres to the end of the welding wire, an arc cannot be generated between the welding wire and the base material, which can cause delays in the welding process.

The following Patent Document 1 discloses a welding method that performs a slag removal process in which the welding wire is repeatedly moved back and forth at high speed toward the base material, the workpiece, to remove the slag. In this welding method, the slag removal process is performed by moving the welding wire back and forth at high speed at a constant frequency.

Patent No. 5230600

In the welding method described in Patent Document 1, the welding wire is moved back and forth at high speed at a constant frequency, so depending on the frequency set, the slag may not be completely destroyed, which can lead to an increase in tact time. In addition, depending on the frequency set, the base material may be scratched, which can lead to reduced welding quality.

Therefore, one of the objectives of the present invention is to provide a wire feeding system and a wire feeding method that can shorten the tact time and improve welding quality.

The wire feeding system according to one aspect of the present invention includes a wire feeding unit that feeds a welding wire, and a wire feeding control unit that controls the wire feeding unit to perform forward and reverse feeding that alternately repeats forward feeding, in which the welding wire is fed in a forward direction, and reverse feeding, in which the welding wire is fed in a reverse direction. The wire feeding control unit controls the wire feeding unit to feed the welding wire forward and reverse during the slow-down feeding process at the start of an arc while a voltage for generating an arc is continuously applied, and at least to increase the peak speed during forward feeding and reverse feeding, and to lengthen the duration of each of the alternating forward and reverse feeding.

According to this aspect, during the slow-down feed process at the start of the arc, the welding wire is fed in both forward and reverse directions, and the peak speed during forward feed and reverse feed can be gradually increased, or the duration of each of the forward feed and reverse feed can be gradually increased. Therefore, even if slag is present between the welding wire and the base material, for example, the slag can be destroyed or removed during the slow-down feed process.

In the above aspect, a memory unit may be further provided that stores an arc history regarding the success or failure of the arc for each section of arc welding, and the wire feed control unit may change at least either the degree to which the peak speed is increased or the degree to which the duration is extended based on the stored arc history.

According to this aspect, it is possible to identify sections of arc welding where arc generation has failed in the past, and to change the degree to which the peak speed is increased during forward feed and reverse feed, and the degree to which the duration of forward feed and reverse feed is increased, depending on the severity of the failure. Therefore, it is possible to identify welding sections where slag is likely to be present, and perform different forward and reverse feeds for each identified welding section, making it possible to efficiently destroy and remove slag.

In the above aspect, the arc history includes the number of times an arc fails to be generated or the percentage of times an arc fails to be generated, and when the number of times exceeds a predetermined number or the percentage exceeds a predetermined percentage, the wire feed control unit may at least either increase the peak speed to a degree greater than the currently set degree and increase the duration to a degree greater than the currently set degree in the peak speed and duration in the slow-down feed process of the corresponding arc welding section.

According to this aspect, different forward and reverse feed can be performed for each section of the arc welding depending on the number and proportion of arc generation failures, which can further increase the efficiency of slag destruction and removal.

In the above aspect, the predetermined number of times and the predetermined ratio may be set and changed for each section of arc welding.

According to this aspect, the threshold number of times and the threshold ratio can be set and changed for each section of arc welding, making it possible to flexibly respond to sections where slag is likely to be present.

A wire feeding method according to another aspect of the present invention is a wire feeding method executed in a wire feeding system that feeds welding wire, and includes a feeding step of feeding the welding wire, and a control step of controlling the feeding of the welding wire in the feeding step so as to perform forward and reverse feeding in which forward feeding of the welding wire in a forward direction and reverse feeding of the welding wire in a reverse direction are alternately repeated, and the control step controls the feeding of the welding wire in the feeding step so as to feed the welding wire in forward and reverse directions while a voltage for generating an arc is continuously applied during the slow-down feeding process at the start of an arc, and at least so as to increase the peak speed during forward feeding and reverse feeding, and to lengthen the duration of each of the alternately repeated forward and reverse feedings.

According to this aspect, during the slow-down feed process at the start of the arc, the welding wire is fed in both forward and reverse directions, and the peak speed during forward feed and reverse feed can be gradually increased, or the duration of each of the forward feed and reverse feed can be gradually increased. Therefore, even if slag is present between the welding wire and the base material, for example, the slag can be destroyed or removed during the slow-down feed process.

The present invention provides a wire feeding system and a wire feeding method that can shorten the tact time and improve welding quality.

1 is a block diagram illustrating a schematic configuration of a wire feeding system according to an embodiment; 11 is a timing chart for explaining an example of changing peak speeds and durations in forward feed and reverse feed. 4 is a flowchart for explaining an example of a wire feeding method according to the embodiment.

A preferred embodiment of the present invention will be described with reference to the attached drawings. In each drawing, the same reference numerals are used to denote the same or similar configurations.

FIG. 1 is a block diagram illustrating a schematic configuration of a wire feeding system according to the present invention. The wire feeding system 1 is a system that feeds a welding wire 4 wound around a wire reel 2 to a welding torch 3 that performs arc welding. The wire feeding system 1 includes, for example, a wire feeding unit 10, a control unit 15, and a memory unit 18. Note that the wire feeding unit 10, the control unit 15, and the memory unit 18 do not need to be included in the same device. For example, they may be distributed among a wire feeding device including the wire feeding unit 10, a control device including the control unit 15, and a storage device including the memory unit 18. The memory unit 18 stores, for example, arc history information 19. The arc history information 19 stores, for example, history information related to arc welding.

The wire feeder 10 includes a first wire feeder 11, a wire buffer 12, and a second wire feeder 13. Each part of the wire feeder 10 is described in detail below.

The first wire feeder 11 feeds the welding wire 4 wound on the wire reel 2 toward the welding torch 3. The first wire feeder 11 has, for example, a roller (not shown) that moves the welding wire 4 forward or backward, a motor (not shown) that rotates the roller, and an encoder (not shown) that detects the rotational position of the motor, etc. The forward movement of the welding wire 4 means that the welding wire 4 moves in the direction of the welding torch 3 (hereinafter also referred to as the "forward direction"), and the backward movement of the welding wire 4 means that the welding wire 4 moves in the direction of the wire reel 2 (hereinafter also referred to as the "reverse direction").

The motor of the first wire feeder 11 rotates the roller so that the welding wire 4 moves in the forward or reverse direction according to instructions from the control unit 15. Illustratively, when welding, the first wire feeder 11 feeds the welding wire 4 in the forward direction according to instructions from the control unit 15.

The second wire feeder 13 feeds the welding wire 4 stored in the wire buffer 12 (described later) to the welding torch 3. The second wire feeder 13 has, for example, a roller, a motor, and an encoder, similar to the first wire feeder 11 described above. These rollers, motor, and encoder are similar to those of the first wire feeder 11, so a description of them will be omitted here.

For example, when welding, the second wire feeder 13 follows instructions from the control unit 15 to feed the welding wire 4 to the welding torch 3 by alternately and quickly repeating forward and reverse feeding, which feeds the welding wire 4 in the forward direction and reverse feeding, which feeds the welding wire 4 in the reverse direction.

The wire buffer 12 is provided between the first wire feeder 11 and the second wire feeder 13. The wire buffer 12 stores the welding wire 4 fed by the first wire feeder 11 and passes the stored welding wire 4 to the second wire feeder 13. The amount of welding wire 4 stored in the wire buffer 12 (hereinafter also referred to as the "buffer amount") varies based on the amount of welding wire 4 fed in the forward direction by the first wire feeder 11 and the amount of welding wire 4 fed in the forward direction by the second wire feeder 13.

For example, when the amount of welding wire 4 fed in the forward direction by the first wire feeder 11 is greater than the amount of welding wire 4 fed in the forward direction by the second wire feeder 13, the buffer amount increases. On the other hand, when the amount of welding wire 4 fed in the forward direction by the first wire feeder 11 is less than the amount of welding wire 4 fed in the forward direction by the second wire feeder 13, the buffer amount decreases.

By converting this increase or decrease in the buffer amount into the length of the welding wire 4 and adding or subtracting it from the reference length, the buffer amount can be expressed as the length of the welding wire 4 contained in the wire buffer 12.

The control unit 15 shown in FIG. 1 is physically configured, for example, by a control unit including a processor, a memory (storage device), and a communication interface. The control unit 15 realizes the function of, for example, the wire feed control unit 16 shown in FIG. 1 by the processor executing a predetermined program stored in the memory.

The wire feed control unit 16 controls the first wire feed unit 11 and the second wire feed unit 13. Specifically, the wire feed control unit 16 outputs a feed command value to the first wire feed unit 11 and the second wire feed unit 13. The feed command value may include, for example, a feed speed, or may include a value for calculating the feed speed. The first wire feed unit 11 and the second wire feed unit 13 perform forward feed or forward/reverse feed at a feed speed corresponding to the feed command value.

The wire feed control unit 16 controls, for example, the execution of a slow-down feed process. The slow-down feed process is a process included in the arc start process executed before starting the welding process. Specifically, after a welding start command, the welding wire 4 is fed at a slow-down feed speed slower than the feed speed during steady welding, with a predetermined time as the upper limit, to generate an arc. In the slow-down feed process in this embodiment, for example, the welding wire 4 is fed while being fed forward and backward. The forward and reverse feed executed in the slow-down feed process is executed in a state in which a voltage for generating an arc is continuously applied. The voltage for generating an arc is output by, for example, a welding power source unit (not shown) that may be included in the wire feed system 1. The welding power source unit may be provided separately and distributed as a welding power source device. The upper limit time and the slow-down feed speed for executing the slow-down feed process can be set in advance as welding conditions.

The slow-down feed process ends when an arc occurs, or when the upper limit time for executing the slow-down feed process has elapsed without an arc occurring. Whether an arc has occurred can be determined by monitoring the welding current. This is because an arc occurs when the welding wire 4 fed toward the base metal is short-circuited with the base metal and a welding current flows.

By performing the slow-down feed process while feeding the welding wire 4 forward and backward, even if there is a foreign object, such as slag, between the welding wire 4 and the base material that prevents the generation of an arc, it is possible to destroy the slag during the slow-down feed process. If the slag can be destroyed or removed, an arc can be generated between the welding wire 4 and the base material, and welding can be started.

Here, the presence of slag between the welding wire 4 and the base material corresponds to, for example, the case where slag is attached to the end of the welding wire 4 or the case where slag is attached to the surface of the base material. There are various situations in which slag is attached, for example, depending on the degree of attachment and the size of the slag. Under such a situation, if forward and reverse feeding is performed at a constant frequency as in Patent Document 1, depending on the frequency set, the slag may not be completely destroyed or the base material may be damaged. Therefore, in the wire feeding system 1 according to this embodiment, it has been decided to vary the forward and reverse feeding movement performed in the slow-down feeding process.

When feeding the welding wire 4 forward and backward in the slow-down feeding process, the wire feed control unit 16 performs at least one of the following (1) and (2).

(1) The wire feed unit 10 is controlled so that the peak speed during forward feed and reverse feed increases during the above-mentioned period. The peak speeds do not necessarily have to be greater than the previous peak speeds during forward feed and reverse feed, and may remain the same, but it is desirable for the peak speeds to gradually increase throughout the above-mentioned period.

(2) The wire feed unit 10 is controlled so that the duration of each of the alternating forward and reverse feeds is lengthened during the above period. The duration does not necessarily have to be longer than the duration of each of the previous forward and reverse feeds, and may remain the same, but it is desirable for the duration to gradually increase throughout the above period.

In this way, by gradually increasing or lengthening the peak speed and duration of forward and reverse feed, the accuracy of destroying and removing slag, etc. can be improved. Therefore, it is possible to reduce the number of areas that are not welded due to the presence of slag, etc., and shorten the tact time.

In addition, at the start of the slow-down feed process, forward and reverse feed is performed with the peak speed and duration suppressed, and if the state in which slag, etc. is not removed and no arc is generated continues thereafter, the peak speed can be gradually increased and the duration gradually lengthened. Therefore, the impact on the base material caused by forward and reverse feed can be suppressed, making it possible to improve welding quality.

Next, referring to Figure 2, an example of changing the peak speed and duration in forward and reverse feed will be described.

The timing chart shown in FIG. 2 shows the change over time in the feed speed in the second wire feeder 13. The vertical axis shows the feed speed, and the horizontal axis shows time.

At time t0, the slow-down feed process at the start of the arc begins, and the welding wire 4 is fed forward and backward toward the base material W. Then, at time t13, an arc is generated, the slow-down feed process ends, and the welding process begins. In both the slow-down feed process and the subsequent welding process, forward and backward feed is performed, but the peak speeds and durations are different. The respective peak speeds and durations can be set in advance as welding conditions.

Of the slow-down feeding process shown in FIG. 2, normal feeding is performed in the periods t0 to t1, t2 to t3, t4 to t5, t6 to t7, t8 to t9, t10 to t11, and t12 to t13. The length of time corresponding to each period is the duration of each normal feeding, and the maximum speed (normal) in each period is the peak speed during each normal feeding.

Similarly, in the slow-down feeding process, reverse feeding is performed in the period from time t1 to t2, the period from time t3 to t4, the period from time t5 to t6, the period from time t7 to t8, the period from time t9 to t10, the period from time t11 to t12, and the period from time t13 to t14. The length of time corresponding to each period is the duration of each reverse feeding, and the maximum speed (negative) in each period is the peak speed during each reverse feeding.

In the figure, the peak speeds during forward feeding from time t0 to time t3 are set to the same magnitude, the peak speeds during forward feeding from time t4 to time t7 are set to be greater than the previous period and to be the same magnitude, and the peak speeds during forward feeding from time t8 to time t13 are set to be greater than the previous period and to be the same magnitude. In other words, the peak speed during forward feeding is set to gradually increase throughout the period of the slowdown feeding process. The peak speed during reverse feeding is also set to be the same as the peak speed during forward feeding.

The duration of each forward feed from time t0 to time t9 is set to the same length, and the duration of each forward feed from time t10 to t13 is set to be longer than the previous period and to be the same length. In other words, the duration of each repeated forward feed is set to gradually become longer throughout the period of the slow-down feed process. The duration of each reverse feed is also set to the same length as the duration of each forward feed.

Next, an example of the procedure in the wire feeding method according to the embodiment will be described with reference to FIG. 3. This procedure begins, for example, when the slow-down feeding process is started in the arc start process.

First, the wire feed control unit 16 outputs a feed command value to the second wire feed unit 13 to feed the welding wire 4 forward and backward at a slow-down feed speed (step S101).

Then, the wire feed control unit 16 controls the second wire feed unit 13 so that the peak speed during forward feed and reverse feed gradually increases and the duration of each of the alternating forward feed and reverse feed gradually increases, for example based on preset welding conditions (step S102).

Next, the control unit 15 determines whether an arc has occurred (step S103). If the determination is NO (step S103; NO), the control unit 15 returns the process to step S101.

If it is determined in step S103 that an arc has occurred (step S103; YES), the control unit 15 performs arc welding (step S104) and ends this procedure.

This procedure also ends if the maximum time for performing the slow-down feed process has elapsed without an arc occurring.

As described above, according to the wire feeding system 1 in the embodiment, during the period when the slow-down feeding process is being performed at the start of the arc, the welding wire 4 can be fed forward and backward, and the peak speed during forward feeding and reverse feeding can be gradually increased, or the duration of each of the forward feeding and reverse feeding can be gradually increased. Therefore, even if slag S or the like is present between the welding wire 4 and the base material W, it is possible to destroy or remove the slag S during the slow-down feeding process.

This reduces the number of areas that are left unwelded due to the presence of slag S, etc., and makes it possible to suppress the impact on the base material W caused by forward and reverse feed.

Therefore, the wire feeding system 1 in this embodiment makes it possible to shorten the tact time and improve welding quality.

[Variations]
The above-described embodiment is intended to facilitate understanding of the present invention, and is not intended to limit the present invention. The elements of the embodiment, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those exemplified, and may be modified as appropriate. For example, the following modifications 1 and 2 may be made.

[Variation 1]
In the above-described embodiment, forward and reverse feeding is performed in the slow-down feeding process, but the present invention is not limited to this. The welding wire 4 may be forward fed at the start of the slow-down feeding process, and forward and reverse feeding may be performed when it is detected that no arc is generated. For example, a situation in which it is detected that no arc is generated corresponds to a situation in which slag or the like is interposed between the welding wire 4 and the base material. For example, the following (1) to (3) can be used as conditions for determining that slag or the like is interposed between the welding wire 4 and the base material.

(1) The load current of the motor of the second wire feeder 13 exceeds a predetermined current value.
(2) The error between the feed command to the second wire feeder 13 and the response value in the second wire feeder 13 exceeds a predetermined threshold value.
(3) The amount of data stored in the wire buffer 12 exceeds a predetermined amount.

[Variation 2]
In the above embodiment, the peak speed and duration in the slow-down feed process are changed based on the preset welding conditions, but the method of changing them is not limited to this. For example, the degree to which the peak speed is increased and the degree to which the duration is extended may be changed based on the arc history information 19 stored in the memory unit 18.

Arc history information 19 stores history information related to arc welding for each section of arc welding. History information related to arc welding includes, for example, the number of times an arc failed to generate and the percentage of times an arc failed to generate.

When the number of times an arc fails to be generated exceeds a predetermined number, or when the rate at which an arc fails to be generated exceeds a predetermined rate, the wire feed control unit 16 implements at least one of the following (1) and (2) for the peak speed and duration in the slow-down feed process for the corresponding arc welding section.

(1) Increase the peak speed by a degree greater than the currently set degree.
(2) Increase the duration by a degree greater than the currently set degree.

The predetermined number of times and the predetermined ratio can be set for each section of arc welding and can be changed. The predetermined number of times and the predetermined ratio may be set in multiple stages.

1...Wire feeding system, 2...Wire reel, 3...Welding torch, 4...Welding wire, 10...Wire feeding unit, 11...First wire feeding unit, 12...Wire buffer, 13...Second wire feeding unit, 15...Control unit, 16...Wire feeding control unit, 18...Memory unit, 19...Arc history information

Claims (5)

a wire feeder that feeds a welding wire;
a wire feed control unit that controls the wire feed unit so as to perform forward and reverse feeding that alternately repeats forward feeding in which the welding wire is fed in a forward direction and reverse feeding in which the welding wire is fed in a reverse direction;
Equipped with
the wire feed control unit controls the wire feed unit in such a manner that, during a period of a slow-down feed process at the time of an arc start, the welding wire is fed in the forward and reverse directions while a voltage for generating an arc is continuously applied, and at least a peak speed during the forward feed and a peak speed during the reverse feed are increased over time, and a duration of each of the alternately repeated forward feed and reverse feed is increased over time.
Wire feeding system. A memory unit that stores an arc history regarding the success or failure of an arc for each section of arc welding,
the wire feed control unit changes at least one of a degree of increasing the peak speed and a degree of increasing the duration based on the stored arc history.
The wire feeding system of claim 1 . The arc history includes a number of failures to strike an arc or a percentage of failures to strike an arc,
When the number of times exceeds a predetermined number of times or when the ratio exceeds a predetermined ratio, the wire feed control unit at least performs one of the following with respect to the peak speed and the duration in the slow-down feed process of the corresponding arc welding section: increasing the degree of increase of the peak speed to a value greater than a currently set value and increasing the degree of increase of the duration to a value greater than a currently set value.
The wire feeding system of claim 2. The predetermined number of times and the predetermined ratio are set and changeable for each section of the arc welding.
The wire feeding system of claim 3. 1. A wire feeding method performed in a wire feeding system for feeding a welding wire, comprising:
a feeding step of feeding the welding wire;
a control step of controlling feeding of the welding wire in the feeding step so as to perform forward and reverse feeding, which alternately repeats forward feeding in which the welding wire is fed in a forward direction and reverse feeding in which the welding wire is fed in a reverse direction;
Including,
the control step controls the feeding of the welding wire in the feeding step in such a way that, during a period of a slow-down feeding process at the time of an arc start, the welding wire is fed in the forward and reverse directions while a voltage for generating an arc is continuously applied, and at least a peak speed during the forward feeding and a peak speed during the reverse feeding are increased over time , and a duration of each of the alternately repeated forward feeding and reverse feeding is increased over time.
Wire feeding method.