JP3114830B2 - Laser welding control method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding control apparatus, and more particularly to a control technique for monitoring a laser welding state by an AE sensor and performing welding under optimum conditions.

[0002]

2. Description of the Related Art Conventionally, as a control technique such as laser welding, a technique has been proposed in which an AE (acoustic emission) generated during welding is detected, and a welding state is monitored and controlled from a detection signal.

In the working condition monitoring method disclosed in, for example, Japanese Patent Application Laid-Open No. 60-22657, taking ultrasonic welding as an example, the quality of welding is determined by the AE waveform, energy, frequency spectrum, etc. generated during the welding. Focusing on the relationship with the physical quantity, processing the information of the AE wave to monitor the welding work state, and based on this, control the current and voltage of the welding power source, Techniques for controlling the positioning of the cradle have been proposed.

Other similar control methods include, for example,
As disclosed in JP-A-64-40192, an AE signal accompanying laser processing of a workpiece is detected through one or more AE sensors fixed to the workpiece, and the AE signal is calculated. A processing control method for real-time control while processing and monitoring a laser processing state has been proposed. Further, as disclosed in JP-A-1-210185, the quality of a product is determined based on an AE signal generated at the time of welding. State monitoring devices and the like have been proposed.

[0005]

The welding conditions required for laser welding include laser beam output, welding speed,
The distance between the focal position of the laser beam and the workpiece, the flow rate of the shielding gas, and the flow rate of the assist gas are listed. That is, if any one of these conditions changes more than the allowable value, it may affect the quality of welding.

Specifically, when the actual output value of the laser beam is higher than the set value, irregularities and undercuts are likely to occur in the welding beam. Conversely, if it is lower than the set value, the penetration depth becomes shallower.

If the distance between the focal position of the laser beam and the workpiece is shorter than the set value, irregularities and undercuts of the welding beam are likely to occur. Conversely, if the distance is longer, the penetration depth becomes shallower.

When the flow rate of the shielding gas and the flow rate of the assist gas are small, blow holes are likely to occur.
Even when the flow rate is large, irregularities are likely to occur in the blow holes and weld beads.

However, the laser processing control and the laser processing monitoring and control method using the conventional AE sensor described above do not take measures to address all of these problems, but merely provide an AE signal and a welding power source (a welding power source). ), And when a welding abnormality is detected from the AE signal, it merely controls the output current or voltage of the welding power source or controls the position of the workpiece. If the cause, for example, the flow rate of the shield gas, the flow rate of the assist gas, or the like is abnormal, it cannot be dealt with. Therefore, sufficient laser welding control cannot be performed, and practical use has been difficult.

[0010] Further, at the site where laser welding control is performed,
In an environment where various work noises are generated, the AE sensor detects noises other than welding, and there is a high possibility that erroneous recognition occurs in monitoring the welding state.

The present invention has been made in view of the above points, and a purpose thereof is to specifically diagnose what the above-mentioned welding conditions correspond to when the abnormality of the laser welding is detected by the AE sensor. Another object of the present invention is to provide a laser welding control device that enables optimal control of laser welding based on the diagnosis result.

Another object of the present invention is to provide a laser welding monitoring and control device capable of accurately performing laser welding monitoring and control based on an AE signal without being affected by noise.

[0013]

In order to achieve the above object, the following laser welding control system is basically proposed.

One of them is that when performing laser welding, a sound generated at the time of laser welding is detected by an AE sensor, and this AE signal is previously stored in reference data (this reference data is generated when the welding is performed under appropriate welding conditions). If the actual AE signal is equal to or larger than the reference data, the AE signal is compared with the AE signal pattern of various unsuitable welding conditions (this AE signal is obtained by storing the AE signal in advance). The signal pattern is obtained by preliminarily examining and storing an AE signal pattern at the time of welding that is generated when various welding conditions such as laser output, laser beam focus positioning, shield gas flow rate, assist gas flow rate, and the like are out of an allowable range.) If the AE signal is similar to any one of the AE signal patterns, the welding condition corresponding to the pattern is corrected (this is referred to as the first method). And control system).

The other is that a sound generated during laser welding is detected by an AE sensor, and this AE signal is compared with reference data similar to the above-mentioned first control method. In the following cases, laser output, laser beam focus positioning, shielding gas flow rate,
The welding conditions such as the assist gas flow rate are prioritized, and the welding conditions are slightly changed according to the order. The AE signal after the minute change is compared with the reference data to calculate the difference between the reference data and the AE signal. If the welding conditions become smaller, the welding conditions that have been slightly changed are corrected by further changing them (this change is a change in the same direction as the direction that has been changed slightly). If the AE signal difference becomes large, the welding condition is returned to the original, the welding condition of the next rank is minutely changed, and the AE signal after the minute change is compared with the reference data as in the previous order. A control method for correcting welding conditions is proposed (this is referred to as a second control method).

This second control method can be adopted as a part of the first control method.

For example, in the first control method, when there is one of the various welding conditions in which the AE signal pattern of the inappropriate welding condition is indistinguishable (for example, of the welding conditions, Taking the welding conditions of the laser output value and the laser focus position as an example, when the laser beam output is lower than the allowable range and when the laser focus position is out of the proper range, the AE signal patterns generated together The details are described in the examples), and the welding conditions to be processed are prioritized.
The same correction is performed as in the control method (the third control method).

In connection with these control methods, an AE signal detected from the AE sensor is a detection signal in a transitional state at the start and end of laser welding and a sound other than a welding sound from a work site. A method is proposed in which noise is reduced and compared with the reference data.

[0019]

According to the first control method, A generated at the time of welding is used.
By comparing the E signal with the reference data, it is known that the welding condition is not appropriate. Further, by comparing the AE signal with the AE signal pattern of various unsuitable welding conditions, the inappropriate welding condition is determined by various welding conditions ( For example, it is possible to determine which one among the laser output, the focus position of the laser beam, the shielding gas, the assist gas flow rate, etc.), and it is possible to correct the welding conditions obtained from various welding conditions. Therefore, while monitoring the state of laser welding in real time, appropriate welding control is enabled.

According to the second control method, it is possible to correct the welding conditions to obtain a target without creating an AE signal pattern of various inappropriate welding conditions as in the first control method.

That is, in the present method, when it is determined that the welding condition is abnormal by comparing the AE signal with the reference data, the laser output, the focus positioning of the laser beam, the shield gas flow rate, the assist gas flow rate and the like are determined. Various welding conditions are slightly changed in the direction of increase or decrease in accordance with the setting order, and if the difference between the AE signal and the reference data after the change in welding becomes small, the welding conditions to be subjected to the minute change are currently in an inappropriate state. Thus, a so-called diagnosing operation of welding conditions is performed.

If the welding conditions determined to be unsuitable are further changed in a direction in which the difference between the AE signal and the reference data becomes smaller, the AE signal falls within the range of the reference data and the welding conditions can be restored to the optimum. .

On the other hand, if the difference between the reference data and the AE signal becomes large due to a slight (increase / decrease) change in the welding condition, the welding condition is not in an inappropriate state. The welding conditions are slightly changed, and diagnosis is performed by slightly changing each welding condition until an inappropriate welding condition is found. Even if the above diagnosis is performed for each welding condition, if the welding state is not improved, if the operation is stopped by issuing an alarm or the like, the reliability of the welding monitoring control is further improved.

The third control method compensates for a part of the first control method, that is, even when there is one in which the AE signal patterns of the unsuitable welding conditions cannot be distinguished in common. Since it is possible to diagnose and correct which welding conditions are inappropriate, the function for improving the welding conditions in real time is further enhanced.

[0025]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 is a system diagram of a laser welding control apparatus according to one embodiment of the present invention.

As shown in FIG. 1, a laser beam 2 output from a laser oscillator 1 is transmitted to a laser welding head 4 via an optical system 3, and the beam 2 is focused and emitted by the laser welding head 4. A workpiece 5 is arranged near the focal point.

An AE sensor 6 is fixed to the laser welding head 4, and a sound during welding is detected by the AE sensor 6 in a wide frequency range. The analog signal output from the AE sensor 6 is input to the preamplifier 7 and amplified. The amplified analog signal is converted into a digital signal by the D / A conversion circuit 11, and the CPU which is the center of the welding control device is converted.
(Microprocessor) 9. Further, a signal detected by the AE sensor 6 before welding (a noise detection signal outside the welding at the work site) is also stored in the background noise data memory 8 as background noise.

Reference numeral 10a denotes a reference data memory (reference data storage means) connected to the CPU 9, in which an AE signal level at the time of optimum welding is stored as reference data for comparing and discriminating signals from the AE sensor 6.

Reference numeral 10b denotes a diagnostic data memory (AE pattern storage means) connected to the CPU 9, in which various welding conditions (for example, laser output, laser beam focus positioning, seal gas flow rate, assist gas flow rate, etc.) are inappropriate (permissible range). In the case where the above is performed, the diagnostic data for determining which welding condition this is is stored. The diagnostic data is obtained by previously examining and storing the pattern of the AE signal generated when various welding conditions such as laser output, laser focal length, shield gas, assist gas, and the like are not appropriate.

The CPU 9 reads the background noise data from the background noise data memory 8 at the time of welding according to the control program 22a, and at the same time, inputs the digital signal (AE signal) output from the D / A conversion circuit 11 and Is calculated to obtain a signal from which background noise has been removed. Further, the actual AE signal is compared with the data read from the reference data memory 10. As a result of this comparison operation, if the actual AE signal is within the range of the reference data,
Welding is performed under the current welding conditions.

Here, the welding head positioning control device 12 connected to the CPU 9 is controlled by the control program 22a to give a control command to the servomotor 13, rotate the screw shaft 23 connected to the servomotor 13, and The laser welding head 4 connected to the shaft 23 is moved up and down. The encoder 14 fixed to the axis of the servomotor 14 feeds back the position signal of the laser welding head 4 to the welding head positioning control device 12.

The laser output control device 15 connected to the CPU 9 is also controlled by the control program 22a, and gives a control command to the laser oscillator 1 to increase or decrease the output of the laser beam.

The assist gas flow controller 16 connected to the CPU 9 is also controlled by the control program 22a, and gives a control command to the assist gas flow controller 18 to increase or decrease the flow rate of the assist gas. Assist gas supply cylinder 21
Is supplied to the laser welding head 4 via the assist gas flow controller 18 and supplied near the focal point of the laser beam.

Similarly, the shield gas flow controller 17 connected to the CPU 9 is also controlled by the control program 22a, and gives a control command to the shield gas flow controller 19,
Increase or decrease the flow rate of the shielding gas. The shielding gas filled in the shielding gas supply cylinder 20 is supplied to the laser welding head 4 via the shielding gas flow controller 19 and supplied near the focal position of the laser beam.

On the other hand, if the result of the comparison between the AE signal and the reference data 22 indicates that the AE signal is equal to or greater than the reference data, the CPU 9 determines that welding is being performed under inappropriate welding conditions and corrects the correction. Diagnosis and correction of welding conditions are executed by the program 22b. That is, the CPU 9 also functions as a welding condition correction unit.

Prior to the description of the diagnosis and correction, the relationship between welding and the signal of the AE sensor will be described with reference to FIGS.

FIG. 2 shows the state from the start to the end of laser welding.
5 shows a detection signal of the AE sensor 6. From the start of welding 0 to the time t ₁ and from the time t ₂ to the end of welding t ₃ , a unique phenomenon that is transient and unstable is observed. For this reason, the reference data read by the CPU 9 is set excluding this transitional data. Thereby, the reliability of the reference data at the time of steady welding is improved.

FIG. 3 is a graph showing the relationship between the detection signal level of the AE sensor 6 during welding and time.

The time from the time 0 to the time t ₁ at the start of welding and the time t ₂ to the time t ₃ at the end of welding are excluded from the control range for the above reason.

W ₀ is a detection signal of the AE sensor 6 when uniform and high-quality laser welding is performed, and the average value of the detection signal levels of the AE sensor 6 from time t ₁ to time t ₂ is represented by S _Set to ₀ . Here, in order to carry out uniform and high-quality welding, the upper limit detection signal level of the AE sensor 6 as the central value of the S ₀ between the time t ₁ of time t ₂ S ₀
+ ΔS, and the lower limit value needs to be between them as S ₀ + ΔS. In other words, S ₀ ± ΔS is the reference data for normal welding.

For example, the waveform W ₁ changes from time t ₁ to time t ₂
, There is a time zone exceeding the upper limit value S ₀ + ΔS, and the waveform W ₂
Is less than the lower limit S ₀ -ΔS, so that uniform and high quality welding cannot be obtained. For this reason,
In order to perform uniform and high-quality welding, it is necessary to control the optimum welding conditions, that is, to control the laser beam output, laser beam focal position, shield gas flow rate, and assist gas flow rate to optimal values. is there.

FIGS. 4 and 5 show specific examples of the waveform of the detection signal of the AE sensor 6 obtained when these welding conditions are out of the appropriate ranges.

[0044] In FIG 4, the waveform W _41, when the output value of the laser beam is low relative to the optimum range, or a waveform that occurs when the focal position of the laser beam is not in the optimum range. Waveform W ₄₂ is a waveform when the output of the laser beam is high relative to the optimum range. Each of the waveforms W ₄₁ and W ₄₂ has a characteristic that the frequency is low and the irregularities of the waveform are relatively small.

[0045] In FIG. 5, the waveform W _50, the flow rate of shielding gas is not in the optimal range, even if the flow rate is high, a waveform appearing in the case small. When the flow rate of the assist gas is large, a waveform similar to the waveform ₅₀ appears.
The feature is that the detection signal level of the AE sensor 6 has irregularities.

The waveform W ₆₀ represents a waveform obtained when the flow rate of the assist gas is less than the optimal range, the detection signal level is high abnormally high frequencies is characterized. This is due to the metal plasma generated when the flow rate of the assist gas is small.

In order to perform uniform and stable welding, it is necessary to constantly monitor the welding state and control each welding condition in real time so as to fall within an appropriate range. Here, the welding state is detected by one AE sensor 6,
The procedure for controlling each welding condition based on the correction program 22b will be described below.

FIG. 6 shows a control flow of the laser welding conditions executed by the correction program 22b. (A)-(k)
Are the steps in the flow.

First, in (a), it is determined whether or not the detection signal level of the AE sensor 6 is within an appropriate range (within the reference data). When the detection signal level is equal to or less than the lower limit S ₀ -ΔS or equal to or greater than the upper limit S ₀ + ΔS,
(B) The subsequent welding conditions are corrected. If the detection signal level is within the proper range, the process returns to (k), and it is checked again at (a) whether the detection signal level is within the proper range.

[0050] In (b), when the waveform of the detection signal is similar to W ₄₁ or W ₄₂ in FIG. 4, or the focal position of the laser beam is out of the proper range, or the output value of the laser beam Is either out of the proper range,
In this case, priorities are set, and first, in (e), the positioning control of the laser welding head is performed, and the focus position of the laser beam is determined and the optimal control is performed. The optimal control of the focus position will be described later in detail.

At (f), it is checked again whether the detection signal is within the proper range. If the detection signal falls within the proper range, the process is terminated, and the process returns to (k). If it is out of the proper range,
Since there is a cause other than the focal length, the output value of the laser beam is controlled so as to fall within an appropriate range in (g). Here, when the detection signal level is equal to or higher than the upper limit value S ₀ + ΔS of the appropriate range, the output value of the laser beam is reduced. When the detection signal level is equal to or lower than the lower limit value S ₀ −ΔS of the appropriate range, the output value of the laser beam is increased. Control so that it falls within the appropriate range.

[0052] (b), the waveform of the detection signal if neither W ₄₁ and W _42, advances (c), the waveform of the detection signal to check whether similar to waveform ₅₀ of FIG. If similar to the waveform W _50, to flow the proper value of the shielding gas, is also for both cases it is less and often, also, in some cases the flow rate of the assist gas is large. Here, to determine which of these three,
First, prioritize the flow of shielding gas by a small amount. At this time, if the detection signal waveform is improved, the flow rate is further reduced, and the process proceeds to the optimum waveform (k). Conversely, if the detection signal waveform becomes worse when the flow rate of the shield gas is reduced, the flow rate of the shield gas is returned to the original flow rate. Next, the flow rate of the shielding gas is slightly increased. If the detection signal waveform at this time is improved, the flow rate is further increased, and the process proceeds to the optimum waveform (k).

Conversely, if the detected waveform becomes worse when the flow rate of the shield gas is increased, the flow rate of the shield gas is returned to the original flow rate. If the welding conditions are improved by adjusting the shielding gas, then the flow rate of the assist gas is reduced by a very small amount. At this time, if the detection signal waveform is improved, the flow rate is further reduced, and the process proceeds to (k), which is closer to the optimum waveform.

If the detection signal becomes worse when the flow rate of the assist gas is increased, the flow rate of the assist gas is returned to the original flow rate, and the process proceeds to (k).

[0055] (c), the case the waveform of the detection signal, if not similar to the waveform W _50, which proceeds (d), the waveform of the detection signal is similar to the waveform W ₆₀ in FIG. 5, Since the flow rate of the assist gas is smaller than the appropriate range, the flow rate is increased so that the detection signal waveform falls within the appropriate range.

As described above, when the detection signal does not fall within the appropriate range even after controlling the respective welding conditions, the welding is stopped halfway as abnormal.

Here, the optimal control of the focal position of the laser beam performed in FIG. 6E will be described with reference to FIGS.

In FIG. 7A, the laser beam is condensed by the parabolic mirror 30 into a laser beam 2. The focal length f ₀ of this laser beam is determined by the physical dimensions of the parabolic mirror. When performing laser welding, it is optimal that the focus of the laser beam is on the surface of the butted portion of the workpieces 5a and 5b.

However, the workpiece 5a or 5b is often deformed except for the machined one, and it is necessary to always control the laser welding head appropriately. FIG. 7 (2) shows a case where the focal position is above the surface of the workpiece, and FIG. 7 (3) shows a case where the focal position is within the workpiece.

A method of detecting these three focal position states by the AE sensor 6 and performing optimal control will be described below.

FIG. 8A shows a case where the focal position is on the surface of the workpiece, and the detection signal waveform of the AE sensor 6 at this time is the waveform W ₀ of FIG. 8A. .

FIG. 8 (2) shows that the laser welding head is
mm are those which represent an elevated state, the detection signal waveform at this time, a W ₁₁ (2 ') in FIG. 8, the average signal level S ₀ -DerutaP _11, and becomes lower than the optimum value S ₀ .

FIG. 8C shows that the laser welding head is Δl
mm and a representation of the descent is allowed state, the detection signal waveform at this time, a W ₁₂ (3 ') in FIG. 8, the average signal level, S ₀ -DerutaP ₁₂ next, than the optimum value S ₀ Lower.

FIG. 9 (1 ') shows a case where the focal point is located above the workpiece, and the detection signal waveform of the AE sensor 6 at this time is a waveform ₂₀ of FIG. The signal level is S ₀ −ΔP ₂₀ , which is lower than the optimum value S ₀ .

FIG. 9 (2 ') shows a state in which the laser welding head is further raised by .DELTA.l mm from that of FIG. 9 (1'), and the detection signal waveform at this time is (2 ') in FIG. ) is a waveform W ₂₁ of the average signal level (S ₀ -ΔP ₂₀₎ -Δ
Next P _21, further detection signal level decreases.

FIG. 9 (3 ') shows a state in which the laser welding head is further lowered by .DELTA.l mm from that of FIG. 9 (1'), and the detection signal waveform at this time is shown in FIG. 9 (3). a waveform W _22, the average signal level (S ₀ -ΔP ₂₀₎ + ΔP
₂₂ and the detection signal level rises.

[0067] (1 ') in FIG. 10, when the focal position is in the object to be welded, the detection signal waveform of the AE sensor 6 at this time, the waveform W ₃₀ (1) in FIG. 10, the average signal level S ₀ -ΔP _30, and becomes lower than the optimum value S _0.

FIG. 10 (2 ') shows a state where the laser welding head is raised by .DELTA.l mm from that of FIG. 1 (1'). At this time, the detection signal waveform is the waveform shown in FIG. 10 (2). W
₃₁ and the average signal level is (S ₀ −ΔP ₃₀ ) + ΔP ₃₁
And the detection signal level rises.

FIG. 10 (3 ′) shows a state where the laser welding head is lowered by Δl mm from FIG. 10 (1 ′), and the detection signal waveform at this time is the waveform of FIG. 10 (3). W
₃₂ , and the average signal level is (S ₀ −ΔP ₃₀ ) −ΔP ₃₂
And the detection signal level decreases.

FIG. 11 shows a control flow for controlling the laser welding head and setting the focal position of the laser beam at an optimum position.

According to the present embodiment, the state of laser welding is constantly monitored on-line, and if any of various laser welding conditions is inappropriate, it is detected in real time and corrected. A stable and high quality laser welded product can be manufactured.

The above welding control method is generated when various welding conditions such as laser output, laser beam focus positioning, shield gas flow rate, assist gas flow rate, etc., are out of an allowable range as diagnostic data of welding conditions. A during welding
The E signal pattern is used, but without using such diagnostic data, these various types of welding conditions are prioritized, and each welding condition is slightly changed until the welding is improved, and the change in the welding condition is AE. Which welding condition should be corrected may be diagnosed based on the comparison between the signal and the reference data.

[0073]

As described above, according to the present invention, when an abnormality in laser welding is detected by the AE sensor, it is specifically diagnosed to what the above-mentioned welding conditions correspond to the abnormality, and the diagnosis is made. Enables optimal control of laser welding based on the results.

In addition, by taking measures against noise such as on-site noise, erroneous control can be prevented and reliability can be improved.

[Brief description of the drawings]

FIG. 1 shows a system of a laser welding control apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram showing detection signals of an AE sensor from the start to the end of laser welding.

FIG. 3 shows a relationship between a detection signal level of an AE sensor during welding and time.

FIG. 4 is an explanatory diagram of a waveform of a detection signal of an AE sensor obtained when welding conditions are out of appropriate ranges.

FIG. 5 is an explanatory diagram of a waveform of a detection signal of an AE sensor obtained when welding conditions are out of appropriate ranges.

FIG. 6 is a flowchart in the case of correcting welding conditions at the time of welding.

FIG. 7 is an explanatory diagram of optimal control of a focal position of a laser beam.

FIG. 8 is an explanatory diagram of optimal control of a focal position of a laser beam.

FIG. 9 is an explanatory diagram of optimal control of a focal position of a laser beam.

FIG. 10 is an explanatory diagram of optimal control of a focal position of a laser beam.

FIG. 11 is a flowchart of optimal control of a focal position of a laser beam.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser oscillator, 2 ... Laser beam, 4 ... Laser welding head, 5 ... Workpiece, 6 ... AE sensor, 8 ... Background noise data memory, 9 ... CPU (welding condition correction means), 10a
... Reference data memory, 10b ... Diagnostic data memory (AE
Pattern data memory), 12 ... welding head positioning control device (laser beam focus positioning control device), 15 ...
Laser output control device, 16: assist gas flow control device, 17: shield gas flow control device, 22a: control program, 22b: correction program.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigetaka Takeuchi 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside the Kokubu Plant of Hitachi, Ltd. (72) Inventor Osamu Matsushima 1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture No. 1 Inside Hitachi Kokubu Plant, Hitachi, Ltd. (72) Inventor Osamu Isshiki 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside Kokubu Plant, Hitachi, Ltd. (72) Inventor Teruyoshi Yoshiike Hitachi, Ibaraki 2-9-1, Aisecho Inside Hitachi Equipment Engineering Co., Ltd. (56) References JP-A-50-58698 (JP, A) JP-A-58-9983 (JP, A) JP-A-4-313473 (JP) JP-A-4-75817 (JP, A) JP-A-52-88993 (JP, A) JP-A-59-220294 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B23K 26/00 G01N 29/14

Claims (9)

(57) [Claims] 1. Occurs when performed under appropriate welding conditions
Check the AE signal in advance and store it as reference data,
In addition, laser output, laser beam focus positioning,
Allows various welding conditions such as flow gas flow and assist gas flow.
AE signal pattern during welding that occurs when it is out of range
AE signal patterns for various unsuitable welding conditions
When performing laser welding, a sound generated at the time of laser welding is detected by an AE sensor.
The E signal by comparing with the reference data, when the actual AE signals of the reference data or or less, the AE signal compared to AE signal pattern of the various non-appropriate welding conditions, the AE signal A laser welding control method comprising: correcting a welding condition corresponding to one of the AE signal patterns if the pattern is similar to the AE signal pattern. Wherein when the AE signal pattern of the non-appropriate welding conditions in the prior SL various welding conditions are present which indistinguishable in common, prioritize the welding conditions to be the subject, The welding condition is slightly changed in accordance with the order, and the AE signal after the minute change is compared with the reference data. If the difference between the reference data and the AE signal becomes small, the welding condition after the minute change is further changed in the same direction. corrected by making variable ized in, whereas, the larger the reference data · AE signal difference by trace changes in the welding conditions and pull the welding conditions based on, and the welding condition of the next rank is trace changes, claim 1 to perform the preceding rank similar correction of the the AE signal after trace changes reference data comparison operation on the welding conditions
The laser welding control method according to the above. 3. Occurs when performed under appropriate welding conditions.
Check the AE signal in advance and store it as reference data,
When performing laser welding, the sound generated during laser welding is detected by an AE sensor, and this AE signal is used as a reference data in advance.
When the actual AE signal is equal to or greater than the reference data, the welding conditions such as laser output, laser beam focus positioning, shield gas flow rate, assist gas flow rate, etc. are prioritized. The welding conditions are minutely changed according to the order, and the AE signal after the minute change is compared with the reference data, and if the difference between the reference data and the AE signal becomes small, the welding condition with the minute change is further changed.
Corrected by making variable ized in the same direction, whereas, the larger the reference data · AE signal difference by trace changes in the welding conditions and pull the welding conditions based on the welding condition of the next rank is trace changed A laser welding control method characterized in that the welding condition is corrected by comparing and calculating the AE signal after the minute change and the reference data in the same manner as the previous ranking. 4. AE signal detected from the previous SL AE sensor, mosquitoes <br/> Tsu noise other than welding sound from the detection signal and the worksite in a transitional state at the end welding at the start of laser welding are reports open compared with the reference data is to so that set
The laser welding control method according to claim 1 . 5. A even if the correction of each species welding conditions, when the AE signal does not fall within the scope of the reference data were to stop the welding operation by an alarm 請
The laser welding control method according to claim 1 . 6. An AE sensor for detecting a sound generated by laser welding, (b) a laser output control means,
(C) laser beam focus position control means for controlling the laser beam focus position with respect to the workpiece, (d) shield gas flow rate control means, (e) assist gas flow rate control means, and (f) under appropriate welding conditions. A that occurs when done
A reference data storage means for storing the E signal as previously examined reference data, (g) Le chromatography The output, the focus position of the laser beam, the shielding gas flow rate, if the various welding conditions of the assist gas flow rate, etc. was out of tolerance The AE signal pattern at the time of welding that occurs during welding is checked in advance and the A
AE signal pattern storage means for storing as an E signal pattern; and (h) comparing an actual AE signal at the time of welding detected by the AE sensor with the reference data, and determining whether the AE signal is equal to or greater than the reference data. In that case, the AE
The signal is compared with the AE signal patterns of the various unsuitable welding conditions, and it is determined whether the AE signal is similar to the AE signal pattern. If the AE signal is similar to any of the AE signal patterns, A laser welding control device comprising: welding condition correcting means for correcting a corresponding welding condition. 7. An AE sensor for detecting a sound generated by laser welding, (b) a laser output control means,
(C) laser beam focus position control means for controlling the laser beam focus position with respect to the workpiece, (d) shield gas flow rate control means, (e) assist gas flow rate control means, and (f) under appropriate welding conditions. A that occurs when done
A reference data storage means for storing the E signal as previously examined reference data, (g) Le chromatography The output, the focus position of the laser beam, the shielding gas flow rate, if the various welding conditions of the assist gas flow rate, etc. was out of tolerance The AE signal pattern at the time of welding that occurs during welding is checked in advance and the A
AE signal pattern storage means for storing as an E signal pattern; and (h) comparing an actual AE signal at the time of welding detected by the AE sensor with the reference data, and determining whether the AE signal is equal to or greater than the reference data. case, predetermined correction program namely laser output, the focus position of the laser beam, the shielding gas flow rate, to various welding conditions follow have fine amount changes previously assigned priority to the assist gas flow rate, etc.,
The AE signal after the minute change is compared with the reference data, and when the difference between the reference data and the AE signal becomes small, the welding condition that has been minutely changed is corrected by further changing in the same direction . If the difference between the reference data and the AE signal becomes large due to the slight change in the welding condition, the welding condition is returned to the original, the welding condition of the next rank is slightly changed, and the AE signal after the minute change in the same manner as the previous rank. And comparing the reference data with the reference data to correct the welding conditions.
A laser welding control device comprising: a correction unit that executes a program . 8. Of the prior Symbol AE signals that will be detected from the sensor, mosquito <br/> noise other than welding sound from the detection signal and the worksite in a transitional state at the end welding at the start of laser welding The laser welding control device according to claim 6 or 7, further comprising a cutting means. If 9. not improved welding by the correction of the previous SL various welding conditions, any one of claim 6 through claim 8 comprising means for automatically stopping the welding outputs an alarm
The laser welding control device according to any one of the preceding claims.