JPH1110334A - Method for controlling input heat during pushing in stud welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the welded quality by pushing a stud after generating arc between welding materials, comparing a welding current average value or an electric resistance average value at the time of conducting in the short circuit and the setting reference value and executing the inlet heat control. SOLUTION: A welding voltage detecting circuit VC and a welding current detecting circuit IC, between the terminals in a welding current output circuit 15 of a welding current electric source device 1, or a CPU in a welding control device 3, are arranged to enable the treatments of the detected voltage and the current values. At the time of executing the inlet heat control, firstly, the stud 18 as a reference is pulled up after abutting on the welding material 14, and after generating the arc between the welding materials 14, the stud 18 is pushed for a prescribed time and the welding voltage average value V2a and the welding current average value I2a during conducting in the short circuit are detected, and the electric resistance value Rav= V2a/I2a is calculated and made to the reference value. During the actual operation, the welding voltage average value V2e and the welding current average value I2c are detected with the same method, and the electric resistance value Rav2 is calculated by these values and compared with the reference electric resistance value Rav to control the inlet heat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for generating an arc by pulling up a stud in a stud welding, pressing the stud against a material to be welded after a predetermined time to short-circuit, and detecting an average welding voltage during a short-circuit current. The present invention relates to a method for managing heat input during a stud pressing period.

[0002]

2. Description of the Related Art As a method of judging the quality of a finished appearance, penetration amount, and the like of stud welding, a worker has performed a visual inspection of a stud welded by a worker, and a bending test of hitting with a hammer has been performed. We have judged the quality of welded joints, but we cannot judge the quality of welded joints accurately by visual inspection alone, and the bending test that strikes studs welded with a hammer requires not only excessive labor but also destruction The following quality judgment methods have been proposed as conventional techniques for improving these tests because they are tests.

[0004] In order to ensure welding quality, it is important to obtain required heat input. If welding conditions are not appropriate and the required heat input cannot be obtained, for example, the welding current may be lower than an appropriate value. If the pulling distance is short, or if the welding position is poor, the molten surface of the stud contacts the molten pool of the material to be welded during arcing, causing a short circuit. If this short-circuit frequently occurs, the arc voltage does not continue sufficiently, resulting in insufficient heat input, making it impossible to push the required amount of pushing during pushing, resulting in poor welding. Therefore, in order to check whether the required heat input is obtained, the welding current and the welding voltage during the stud holding period must be constantly monitored.

In the technique of Japanese Patent Application Laid-Open No. 61-242766, quality is determined by measuring and recording a welding current and a welding voltage, particularly a short-circuit current during indentation at the end of welding, using an electromagnetic oscillograph.

As a method for monitoring the welding voltage, there is a method in which the detected welding voltage waveform and welding current waveform are constantly monitored by a monitor device or the like, but the operator must constantly monitor the waveform. Since the monitor device itself is large, when the welding position at a construction site or the like frequently moves, it must be moved in accordance with the welding position, thereby reducing workability. Also, the monitor device is expensive, and if it moves frequently, it may cause a failure.

[0012] As an application of stud welding, a steel plate is disposed on a structure in which steel frames such as H-shaped steel and I-shaped steel are assembled in a building work, a construction work, and the like, and the steel plate (deck plate) is fixed on the steel frame by stud welding. There is thin plate penetration welding. Figure 1 shows that when a steel plate is placed on a steel frame,
It is a steel-frame and steel plate positional relationship figure which shows the state which has produced the clearance gap (clearance) between a steel frame and a steel plate. In the figure, when the steel plate 22 is disposed on the steel frame 21 and the thickness Dp of the steel plate is a thin plate such as 1.2 [mm], for example,
The steel plate 22 undulates, and a gap (clearance) Dc is generated between the steel frame 21 and the steel plate 22.

[0014]

FIG. 2 is a steel plate / stud positional relationship diagram showing the positional relationship between the steel plate and the stud tip when there is a gap between the steel frame and the steel plate. Figure (A)
Is a welding start positional relationship diagram showing a state in which the tip of the stud 18 is in contact with the steel plate 22 immediately after the start of the stud welding, and the position where the tip of the stud 18 is in contact with the steel plate 22 is defined as a reference point P. FIG. 6B is an arcing positional relationship diagram showing a state in which an arc is generated by pulling up the tip of the stud. The tip of the stud has been pulled up from the reference point P in FIG. In position.

FIG. 2C is a short-circuit position relation diagram showing a state in which a command to push in the stud is issued after a preset time has elapsed from the start of welding and the tip of the stud is pushed in to short-circuit. The tip of the stud is located at a position pushed in by a pushing distance Dd from the reference point P in FIG. FIG. 4D is a diagram showing a time course of the tip position of the stud 18 from the start of welding to the end of welding.
The vertical axis indicates the movement amount M of the stud tip, the symbol P indicates the position of the reference point in FIG. 7A, the symbol 〓 indicates the position of 〓 at the stud tip in FIG. The position of 〓 at the tip of the stud in FIG. (B) is shown, and the symbol 〓 indicates the position of 〓 at the tip of the stud in FIG.

FIG. 1E is a diagram showing the time course of the load voltage V0 from the start of welding to the end of welding. In FIG. 9 (E), time ts0 is a short-circuiting point during normal welding that is not such penetration welding, time ts1 is a short-circuiting point during such penetration welding, and the stud tip is a steel plate. This is the time required to move by the thickness Dp and the gap Dc, and becomes large later than the time ts0. Further, at time ts2
Is the point of short circuit when the tip of the stud is pushed into the steel frame at the time of such penetration welding, and the gap (clearance) Dc between the steel frame 21 and the steel plate 22 is indefinite, so the delay from time ts0 to time ts2 Time varies.

Since the gap Dc is indefinite, the arc length Da becomes Du + (Dp + Dc), which is (Dp + D
c) and the variation occurs. further,
In the case of such penetration welding, the actual plunging amount De into which the tip of the stud is pushed into the steel frame is Dd− (Dp + D
c), which is reduced by (Dp + Dc) and the variation is larger than in the case of ordinary welding which is not such penetration welding.

To secure welding quality, it is important to obtain required heat input. The heat input of stud welding is defined as the time integral value of the welding voltage value and welding current value during arc generation by pulling up the stud from the workpiece, and the welding voltage value during short-circuit current conduction by pushing the stud into the workpiece. It is the sum of the welding current value and the time integral value.

If the welding conditions are not appropriate and the required heat input cannot be obtained, for example, if the welding current is larger than the appropriate value, if the pulling distance is short, or if the welding posture is poor, the arc will be increased. During this time, the molten surface of the stud contacts the molten pool of the material to be welded, causing a short circuit. If this short-circuit occurs frequently, the arc does not continue sufficiently, resulting in insufficient heat input, making it impossible to push in a required amount during the pushing, resulting in poor welding. The applicant has separately filed a method for detecting and managing the case where the heat input is insufficient due to the insufficient continuation of the arc.

Even if the short circuit does not occur during the arc generation and the heat input during the arc generation is appropriate, it is later than a predetermined time t21 after the command to push the stud into the workpiece is issued. When a short circuit occurs, the heat input becomes excessive. The present invention solves this problem.

[0051]

According to a first aspect of the present invention, in the method for controlling heat input of stud welding, a stud to be determined is pulled up from a material to be welded to generate an arc, and then the stud is pushed into the material to be welded. The average welding voltage V2c is detected while the short-circuit current is flowing when the short circuit occurs.
A method for comparing the value corresponding to 2c with a predetermined value and displaying a comparison result, a stud welding press-in period heat input management method used for warning, quality judgment, heat input control, and the like.

In the method for controlling heat input of stud welding according to a second aspect of the present invention, after a stud to be a reference is pulled up from a material to be welded to generate an arc, a command to push the stud into the material to be welded is issued, The welding voltage average value V2a and welding current average value I2a are detected during short-circuit current conduction when short-circuiting occurs by the predetermined time t21, and the indentation voltage value based on the welding voltage average value V2a is used as a reference. After raising the stud you want from the material to be welded to generate an arc,
Pressing the stud into the work piece and detecting the welding voltage average value V2c when the same welding current average value I2a as described above is applied during short-circuit current conduction, and determining the welding voltage average value V2c. The indentation period heat input management method for stud welding used for display, alarm, quality judgment, heat input control, etc., by comparing the indentation voltage value V2c to be determined with the indentation voltage value V2a to be used as a reference.

According to a third aspect of the present invention, in the method for controlling heat input of stud welding, after a stud to be a reference is pulled up from a material to be welded to generate an arc, a command to push the stud into the material to be welded is issued, After detecting the welding voltage average value V2a and the welding current average value I2a during the short-circuit current conduction when short-circuiting occurs by the predetermined time t21, the welding voltage average value V2a detected during the short-circuit current conduction is changed to the welding current average value I2a. The resistance value calculation process is used as a reference for calculating the resistance value Rav = V2a / I2a by dividing by the following formula. After the stud to be determined is pulled up from the workpiece to generate an arc, the stud is pushed into the workpiece and the short-circuit current After the average welding voltage V2c and the average welding current I2c are detected during energization, the average welding voltage V2c detected during short-circuit current energization is divided by the average welding current I2c to obtain a resistance value Rav2 = V2c / I2c. Arithmetic And a resistance value comparison process of comparing the resistance value Rav2 to be determined with the reference resistance value Rav. The comparison result is used for display, alarm, quality judgment, heat input control, and the like. This is a method for controlling heat input during the indentation period of stud welding.

According to a fourth aspect of the present invention, in the method for controlling heat input of stud welding, the reference stud is pulled up from the material to be welded, an arc is generated, and a welding voltage average value V1a and a welding current that do not cause a short circuit during the arc are generated. The average welding voltage V2a and the welding current average I2a are detected during the short-circuit current conduction when the average value I1a is detected, and then a command is issued to push the stud into the material to be welded and short-circuited by a predetermined time t21. Is detected, the welding voltage average value V2a detected during short-circuit current
Is divided by the average welding current value I2a to obtain a resistance value Rav = V2a / I
2a, a reference voltage drop calculating process of calculating a voltage drop Vr = Rav × I1a of a product of the average welding voltage V1a, the average welding current I1a, and the resistance Rav so that a short circuit does not occur during arcing; An arc is generated by lifting the stud to be welded from the material to be welded, and then the stud is pushed into the material to be welded to detect the welding voltage average value V2c and the welding current average value I2c during short-circuit current conduction, and then to conduct the short-circuit current conduction. Is divided by the average welding current value I2c to obtain the resistance value R.
av2 = V2c / I2c is calculated, and the voltage drop Vr2 of the product of the average welding current value I1a detected during the arc generation and the resistance value Rav2 is calculated.
= Rav2 × I1a, and a voltage drop comparing step of comparing the voltage drop Vr2 to be determined with the reference voltage drop Vr. The results of the comparison are displayed, alarmed, quality judged, and entered. This is a method for controlling heat input during the indentation period of stud welding used for heat control and the like.

[0060]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Even if a short circuit does not occur during the arc generation and the heat input during the arc generation is appropriate, a predetermined time t21 is determined after a command to push the stud into the workpiece is issued. If a short circuit occurs later than this, the heat input will be excessive, so the method of the present invention indicates, displays an alarm,
This is a method for controlling heat input during the indentation period of stud welding used for quality judgment, heat input control, and the like. The method of managing heat input by determining excessive heat input according to the present invention is to raise the stud from the material to be welded, generate an arc, melt the stud tip and the material to be welded, and then weld the stud to the welded material. In a method of stud welding a stud to a material to be welded by pushing it into a material, for example, as shown in FIG.
Is wavy, a gap (clearance) Dc is generated between the steel frame 21 and the steel plate 22. When the gap becomes larger than an assumed value and the pushing period becomes longer, a stud to be a reference is set. After detecting the welding voltage average value V2a and welding current average value I2a during short-circuit current conduction when short-circuiting is performed by a predetermined time t21 after instructing the material to be welded and then detecting during short-circuit current conduction. A reference resistance value calculating step of calculating the resistance value Rav = V2a / I2a to be a reference by dividing the welding voltage average value V2a by the welding current average value I2a;
The stud to be determined is pushed into the material to be welded, and the welding voltage average value V2c and the welding current average value I2c are detected during short-circuit current conduction, and then the welding voltage average value V detected during short-circuit current conduction.
Resistance value R to be determined by dividing 2c by welding current average value I2c
av2 = V2c / I2c, a determination resistance value calculation process, and a resistance value comparison process of comparing a resistance value Rav2 to be determined with a reference resistance value Rav. The comparison result is displayed.
This is a method for controlling heat input during the indentation period of stud welding used for warning, quality judgment, heat input control, and the like.

Here, some of the terms used in the present application will be described. The term “while the short-circuit current is flowing” refers to a period during which a steady short-circuit current flows in the above-described “short-circuit current period Ts” or the “press-in detection period T2” described later. The stud to be determined is a stud which uses the detection or calculation data of the stud to be welded now for heat input management. The reference stud is a stud that collects detection or calculation data when normal welding is performed before welding the stud to be determined, and controls the heat input of the stud to be determined later based on the collected data. A stud used for The stud used as the reference may be a stud when a normal welding is performed.
The stud is not limited to the purpose of collecting data, but may be any stud that is welded before the stud that is currently being determined and that is to be determined.

[0070]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation will be described below with reference to the drawings. FIG.
(A) shows an output current I when a short circuit occurs by a predetermined time t21 after a command for pushing a stud into a workpiece is given.
FIG. 8B is an output current waveform diagram showing a waveform o, and FIG. 9B shows an output terminal voltage Vd waveform when the stud is short-circuited by a predetermined time t21 after a command to push the stud into the workpiece is given. It is a terminal voltage waveform diagram.

In the figure, welding is started in the following order. When the output current Io is supplied and the stud 18 is pulled up, an arc is generated from the electrode at the tip of the stud in contact with the workpiece 14, and at time t0, the pilot current Ip
Flows. Next, from this time t0, a preset time t
When it becomes 1, the pilot current Ip is switched to the main arc current Ia. Subsequently, the output terminal voltage Vd is detected for a preset detection period T1 during the pulling-up from time t11 when a sufficient time elapses until the main arc current Ia is stabilized. The welding voltage V1 (t) and the welding current I1 (t) during the raising of the time t are detected and integrated by the arithmetic processing circuit CPU.

Next, a first method of calculating the resistance value Rav will be described. During the detection period T1 during the raising, the welding voltage V1 (t) during the raising at the time t is integrated to detect the detection period T1.
The welding voltage average value V1a and welding current I1
(t) is integrated and calculated by dividing by the detection period T1, and the welding current average value I1a is calculated by Expressions 1 and 2, respectively.

(Equation 1)

(Equation 2) When the welding power supply has a constant current characteristic, there is no need to integrate the welding current I1 (t).
(t) may be the welding current average value I1a.

Next, at time t12, a command is issued to push the stud 18 into the workpiece 14, and the stud 18 is pushed into the molten pool and short-circuited. After the short circuit, the detection is started at a sufficient time t21 when the peak current is reduced, and the detection is started at the time t21.
, The welding voltage V2 (t) and the welding current I2 during the pushing at the time t during the detection period T2 during the pushing from the time t22 to the time t22.
(t) is detected, and the resistance value R (t) at the time t is calculated by the equation (3). R (t) = V2 (t) / I2 (t) (Equation 3)

The resistance value R (t) at time t is integrated by the arithmetic processing circuit CPU during the detection period T2 during the pressing, and the average value of the resistance during the detection period T2 during the pressing (hereinafter referred to as the resistance value). ) Calculate Rav by equation (4).

(Equation 4) The resistance value Rav in the detection period T2 during the pushing is the resistance value of the secondary cable 17 and the workpiece 14.

The resistance value Rav is multiplied by the welding current average value I1a in the detection period T1 during the pulling-up of the above-described equation (2), and
The voltage drop Rav · I1a based on the resistance value is calculated.

Next, a second method of calculating the resistance value Rav will be described. If there is no change in the welding current at the time of the short circuit, the arithmetic processing circuit CPU integrates the welding voltage V2 (t) and the welding current I2 (t) during the pushing at the time t, and welds during the welding period T2 during the pushing. The average voltage value V2a and the average welding current value I2a are calculated by Equations 5 and 6, respectively.

(Equation 5)

(Equation 6)

The resistance value Rav is calculated by the equation (7). Rav = V2a / I2a (Equation 7)

FIG. 4A is a load current waveform diagram showing a waveform of the output current Io when a short circuit occurs after a predetermined time t21 after a command for pushing the stud to be determined into the workpiece is issued. FIG. 3B shows the output terminal voltage Vd of the welding power supply device when a short circuit occurs after a command to push the stud to be determined into the workpiece to be welded and later than a predetermined short-circuited welding voltage detection start time t21. FIG. 6 is an output terminal voltage waveform diagram showing the waveform of FIG.

The detection period T during pulling up shown in FIG.
1 and the welding voltage average value V1a detected in FIG.
Are the same as the welding voltage average value V1a and the welding current average value I1a detected in the detection period T1 during pulling shown in FIG. 3B. At a time t12 when the detection of the welding voltage during the arc is completed at the end of the detection period T1 during the pulling shown in FIG. 3B, a predetermined time elapses after the command to push the stud into the workpiece is passed. A short circuit occurs before the welding voltage detection start time t21 during the short circuit, and the average welding current value I2a and the average welding voltage value V2a are detected while the short-circuit current is flowing.

However, at the time t12 at which the welding voltage detection during the arc is completed at the end of the pulling-up detection period T1 shown in FIG. 4B, a command to push the stud into the workpiece is set in advance. No detection occurs during the welding voltage detection start time t21 during the short-circuiting after the elapse of time, and the detection period T2 during the push-in operation despite the arc is still maintained.
Has started. The short-circuit occurs only at the time t2c when the short-circuiting is started later than the welding voltage detection start time t21 during the short-circuiting at the start of the detection period T2 during the indentation. An average welding voltage V2c when current is supplied is detected.

The welding voltage average value V2a detected during the pressing-in detection period T2 shown in FIG. 3B and the welding voltage average value V detected in the pressing-in detection period T2 shown in FIG.
Compare with 2c. In the detection period T2 during pushing shown in FIG. 3 (B), the welding voltage is averaged during the short-circuit current conduction when a short-circuit is caused by a command to push the reference stud into the work to be welded before a predetermined time t21. The value V2a and the welding current average value I2a are detected and the welding voltage average value V2a is detected.
Press-in voltage value based on 2a. Hereinafter, a comparison is made for each claim.

According to the method of claim 1, in the detection period T1 during pulling shown in FIG. 4B, after the stud to be determined is pulled up from the material to be welded to generate an arc, the stud is pushed into the material to be welded. The welding voltage average value V2c at the time of the short circuit is detected, the value corresponding to the welding voltage average value is compared with a predetermined value, and the comparison result is used for display, alarm, quality judgment, and heat input control. As the value corresponding to the welding voltage average value and the predetermined value, the pressing voltage value V2c to be determined by the method of claim 2 and the pressing voltage value V2a as a reference,
A resistance value Rav2 to be determined by the method of claim 3 and a resistance value Rav to be a reference or a voltage drop V to be determined by the method of claim 4.
In addition to r2 and the reference voltage drop Vr, these values and the output characteristics of the welding power supply, physical or chemical factors of the stud, physical or chemical factors of the material to be welded, welding posture, state of the power supply , A value obtained by combining with a work environment such as a secondary cable and other factors.

The method of claim 2 is as follows. In the detection period T1 during pulling shown in FIG. 4 (B), the stud to be determined is pushed into the material to be welded, and the same welding current average value I2a as described above is applied during the short-circuit current application, and the welding voltage average value is applied. V2c is detected, and the welding voltage average value V2c is set as the indentation voltage value to be determined. Comparing the above-described push-in voltage value V2c to be determined with the push-in voltage value V2a to be used as a reference, the push-in voltage value V2c shown in FIG. 4B is larger than the push-in voltage value V2a to be used as a reference shown in FIG. Is also large. Therefore, the heat input during the detection period T2 during the pushing shown in FIG. 4B is larger than the pushing voltage value V2a to be the reference shown in FIG.
Used for display, alarm, quality judgment, heat input control, etc., to control the heat input during the indentation period of stud welding.

According to the method of the second aspect, when the pressing voltage value V2c to be determined during the passage of the short-circuit current and the pressing voltage value V2a to be used as the reference are detected, the same welding current average value I2 is used.
There is a restriction that the current of 2a must be supplied. On the other hand, according to the method of claim 3, the push-in voltage value V2c to be determined while the short-circuit current is flowing and the push-in voltage value V2a to be the reference
Is detected, there is no restriction that a current having a different average value of welding current must be supplied.

The method of claim 3 is as follows. (1) Reference resistance calculation process In the detection period T2 during pushing shown in FIG. 3 (B), short-circuiting was performed by a predetermined time t21 after a command to push the reference stud into the workpiece was issued. During the short circuit, the average welding voltage V2a and the average welding current I2a are detected. The resistance value Rav = V2a / I2a is calculated by dividing the welding voltage average value V2a detected during the short-circuit current conduction by the welding current average value I2a. (2) Calculation process of resistance value to be judged A tod to be judged is pushed into a material to be welded, and an average welding voltage value V2c and an average welding current value I2c are detected during short-circuit current application. The average welding voltage V2c detected during the short-circuit current is divided by the average welding current I2c to obtain a resistance value Rav2 = V2c / I.
Calculate 2c.

(3) Resistance value comparison process The resistance value Rav2 to be determined and the reference resistance value Rav
4B, the push-in voltage value V2c to be determined shown in FIG. 4B is larger than the push-in voltage value V2a used as the reference shown in FIG. While it is larger than the reference indentation voltage value V2a,
The heat input during the detection period T2 during the pressing shown in FIG. At this time, since the resistance value Rav2 to be determined is larger than the reference resistance value Rav, it is used for display, alarm, quality determination, heat input control, and the like to manage the heat input during the indentation period of the stud welding.

According to the method of claim 4, in addition to the effect of the method of claim 3, the comparison result is converted into a voltage value so as to be easily used for heat input control. (1) Calculation process of reference voltage drop In the detection period T1 during pulling shown in FIG. 3B, a welding voltage at which a reference stud is pulled up from the material to be welded to generate an arc and a short circuit does not occur during the generation of the arc. The average value V1a and the welding current average value I1a are detected. The welding current average value I1a is referred to as the welding voltage average value V1a at which no short circuit occurs during the arc generation. The average welding voltage value V2a and the average welding current value I2a are detected during the short-circuit current application when the stud to be the reference is pushed into the material to be welded and short-circuited by the predetermined time t21. The resistance value Rav = V2a / I2a is calculated by dividing the welding voltage average value V2a detected during the short-circuit current conduction by the welding current average value I2a. A voltage drop Vr = Rav × I1a, which is a product of the average welding current value I1a and the resistance value Rav, is used as a reference.

(2) Calculation of judgment voltage drop After the stud to be judged is pulled up from the material to be welded and an arc is generated, the stud is pushed into the material to be welded and the welding voltage average value V2c and the welding current average value are supplied during short-circuit current conduction. I2c is detected. Average welding voltage V detected during short-circuit current
2c divided by the average welding current value I2c to obtain a resistance value Rav2 = V2c.
/ I2c is calculated. The voltage drop Vr2 = Rav2 × I1a, which is the product of the average welding current value I1a and the resistance value Rav2, is used as a reference.

(3) Voltage Drop Comparison Process When the voltage drop Vr2 to be determined is compared with the reference voltage drop Vr, the push-in voltage value V2c to be determined shown in FIG. 4B is shown in FIG. 3B. Since the pushing voltage value V2a is larger than the reference pushing voltage value V2a, the heat input during the detection period T2 during pushing shown in FIG. 4B becomes larger than the heat input in FIG. 3B. At this time, since the voltage drop Vr2 to be determined is larger than the reference voltage drop Vr, it is used for display, alarm, quality judgment, heat input control, and the like, and the heat input during the indentation period of the stud welding is managed.

FIG. 5 shows a stud welding method according to a third aspect of the present invention.
9 is a flowchart of a stud welding intrusion period heat input management method for comparing a resistance value Rav2 to be determined with a reference resistance value Rav. In the figure, step ST1 is
During the short-circuit current conduction during the short-circuit current conduction when a short-circuit is conducted by a predetermined time t21 after the command to push the stud to be the reference into the material to be welded, the short-circuit current conduction detecting the welding voltage average value V2a and the welding current average value I2a Is a detection step. In step ST2, the welding voltage average value V detected during the short-circuit current is supplied.
2a divided by the average welding current value I2a and the resistance value Rav = V2a /
This is the step of calculating I2a, and the steps 1 and 2 are the resistance value calculation steps to be used as references.

Step ST11 is a detection step in which the stud to be determined is pushed into the material to be welded to detect the welding voltage average value V2c and the welding current average value I2c while the short-circuit current is flowing. Step ST12 is a step of calculating the resistance value Rav2 = V2c / I2c by dividing the welding voltage average value V2c detected during the short-circuit current conduction by the welding current average value I2c, and includes steps ST11 and ST1.
Reference numeral 2 denotes a resistance value calculation process to be determined.

In step ST20, the resistance value R to be determined is determined.
This is a resistance value comparison step of comparing av2 with a reference resistance value Rav.

FIG. 6 shows a stud welding method according to a fourth aspect of the present invention.
It is a flowchart of the push-in period heat input management method of the stud welding which compares the voltage drop Vr2 to be determined with the voltage drop Vr to be a reference. Referring to FIG.
Is a detection step during energization of an arc current for detecting an average welding voltage value V1a and an average welding current value I1a in which an arc is generated by raising a reference stud from a material to be welded and a short circuit does not occur during arc generation. . This welding current average value I
1a is the welding current average value I1a used as the reference.

In step ST2, the average welding voltage V2a and the average welding current I2a are detected during the short-circuit current conduction when the stud is short-circuited by a predetermined time t21 after the command for pushing the stud into the workpiece is issued. This is a detection step during the passage of the short-circuit current. Step ST3 is a resistance value calculation step of calculating the resistance value Rav = V2a / I2a by dividing the welding voltage average value V2a detected during the short-circuit current conduction by the welding current average value I2a. In step ST4, a voltage drop Vr = Rav × I1a of a product of the reference welding current average value I1a and the resistance value Rav.
Is a reference voltage drop calculating step of calculating

In step ST11, after the stud to be determined is pulled up from the material to be welded and an arc is generated, the stud is pushed into the material to be welded, and the average welding voltage V2c and the average welding current I2c are detected during short-circuit current application. This is a detection step during the application of the short-circuit current.

Step ST12 is a step of calculating the resistance value Rav2 = V2c / I2c by dividing the welding voltage average value V2c detected during the short-circuit current application by the welding current average value I2c. In step ST13, the welding current average I
The voltage drop Vr2 of the product of 1a and the resistance value Rav2 = Rav2 × I1a
Is a calculation step of calculating a determination voltage drop.

Step ST20 is a resistance value comparison step of comparing the voltage drop Vr2 to be determined with the reference voltage drop Vr.

FIG. 7 is a view showing an embodiment of a stud welding apparatus for carrying out the method of the present invention. The stud welding apparatus shown in FIG. 1 includes a welding power supply device 1, a welding gun 2, and a welding control device 3.
And formed from This welding power supply device 1 includes a welding gun 2
A current command output circuit 5 that outputs an output current Io including a pilot current Ip and a main arc current Ia, and controls the output current Io in accordance with an analog signal output from a welding control device 3 described later. A welding current output circuit 15 comprising a semiconductor switching element such as a thyristor for controlling an output current Io based on a command, and a secondary cable 17
A welding current detection circuit IC for detecting an output current Io output to a stud 18 mounted on the welding gun 2 through the sensor and outputting a welding current detection signal Ic, and a welding voltage detection signal for detecting an output terminal voltage Vd. And a welding voltage detection circuit VC that outputs Vc.

The welding control device 3 receives the welding current detection signal Ic
A / D converter 7 which converts a welding voltage detection signal Idd into a digital welding current detection signal Idd and outputs it to the arithmetic processing circuit CPU, and an A / D converter 7 which converts the welding voltage detection signal Vc into a digital welding voltage detection signal Vdd and outputs it to the arithmetic processing circuit CPU. A / D converter 8, an arithmetic processing circuit CPU which receives a digital welding current detection signal Idd and a digital welding voltage detection signal Vdd, and outputs a digital output signal to be described later, and converts a digital output signal Iod of the arithmetic processing circuit CPU into an analog signal. The D / A converter 6 converts the output signal Ioa to the current command output circuit 5 and outputs it to the current command output circuit 5, a storage circuit 11 for storing welding result data, and a display circuit 12 such as a digital panel for displaying the welding result. . The D / A converter 6, the A / D converter 7, and the A / D converter 8 may be built in the arithmetic processing circuit CPU.

Hereinafter, the operation of the stud welding apparatus according to the embodiment shown in FIG. 7 will be described. When the tip of the stud is pressed to the position where it comes into contact with the workpiece 14 and the start switch 13 arranged on the welding gun 2 is pressed, the stud 18 at the contact position is pulled up to a preset position, Subsequently, a preset pilot current Ip is supplied. When the arc is generated by raising the stud, the pilot current Ip is switched to the main arc current Ia after a preset time. When a predetermined time elapses after the required welding current value has been reached from the start of the supply of the pilot current Ip or the main arc current Ia, the stud 18 is pushed toward the workpiece 14. On the way, the stud 18 is short-circuited to the workpiece 14 and the short-circuit current Is flows for the short-circuit time. During the sampling time T1 and T2 described later in this series of welding operations, the arithmetic processing circuit CPU detects the welding current and the welding voltage.

The output voltage detected by the welding voltage detection circuit VC connected to the output terminal of the welding power supply device 1 indicates the welding state during arcing and short-circuiting and the voltage between the secondary cable 17 and the workpiece 14. The voltage calculated as the average value is not a constant value because it changes greatly depending on the resistance value. Further, the output current detected by the welding current detection circuit IC connected to the output circuit of the welding power supply device 1 changes during arcing and short-circuiting when the welding power supply 1 has a drooping characteristic. The current value calculated as the average value is not a constant value. Therefore, the welding gun 2 is pulled up, and the average value V1a of the welding voltage (hereinafter, referred to as the welding voltage average value during the pulling) and the welding current of the welding current detected during a certain period T1 (hereinafter, referred to as a detection period during the pulling) during the arc generation. The average value I2a of the welding voltage between the average value I1a (hereinafter referred to as the average welding current during pulling) and the short circuit period T2 during pushing (hereinafter referred to as the detection period during pushing) (hereinafter, the welding voltage during pushing). Average value) and an average value I2a of the welding current (hereinafter, referred to as an average welding current value during pushing).

The arithmetic processing circuit CPU is an arithmetic processing circuit which executes the above-described function of FIG. 5 or FIG. 6 by a digital signal. The voltage detection signal Vdd and the digital welding current detection signal Idd are input, and the welding voltage average value V1a for a sampling time T1 described later is input.
Then, the digital welding voltage detection signal Vdd and the digital welding current detection signal Idd detected during the short-circuit current application by inputting the stud into the workpiece and inputting the digital welding current detection signal Idd will be described later. Sampling time T
After detecting the welding voltage average value V2a and the welding current average value I2a, the welding voltage average value V detected during the short-circuit current is supplied.
2a is divided by the average welding current value I2a to calculate the resistance value Rav. Then, the reference welding current average value I1a and the resistance value Rav are calculated.
, And a digital output signal of the resistance value Rav, a digital output signal of the voltage drop Vr, and the like are stored in the storage circuit 11.

Similarly, the stud to be determined also calculates the voltage drop Rav2 · I1a of the product of the welding current average value I1a and the resistance value Rav2 of the stud used as the reference, and calculates the resistance value Rav2.
And the digital output signal of the voltage drop Vr2 are stored in the storage circuit 11.

[1000]

The effects of the present invention are as follows.

(1) In the present invention, a welding voltage detecting circuit VC for detecting a voltage between output terminals of a welding power source and a welding current detecting circuit IC for detecting a welding current are provided. Even when the secondary cable is extended, the quality can be managed by comparing the indentation voltage value V2c to be determined with the indentation voltage value V2a to be determined.

(2) In the present invention, a short-circuit does not occur during the generation of an arc, and a pressing voltage value V2a or a pressing voltage value which is used as a reference when a short-circuit occurs immediately after a command for pressing a stud into a material to be welded is issued. When the reference resistance value Rav or the reference voltage drop Vr is input in advance to the arithmetic processing circuit CPU, the indentation voltage value V2c to be determined and the indentation voltage value V2a to be obtained obtained for each welding of each stud are obtained.
Can be compared with the resistance value Rav2 to be compared or determined with the reference resistance value Rav, and the voltage drop Vr2 to be compared or determined with the reference voltage drop Vr. If this comparison deviates from the acceptable range that affects weld quality,
The worker can be informed by an alarm or the like, and the defective portion can be re-welded again to secure the strength of the member, so that the heat input during the indentation period of arc stud welding is appropriately and easily managed. be able to.

(3) In the present invention, data obtained for each welding of each stud is stored for each welding of each stud, and an arithmetic processing circuit CPU or this data is input to an external storage circuit, for example, a memory card or a personal computer. Then, it can be processed by a personal computer to create and evaluate a histogram or the like, so that it is possible to easily confirm the heat input management during the indentation period of each stud welding.

(4) In the present invention, in the case of stud welding in the field, a cable having a diameter smaller than a specified cable diameter is often used in order to improve workability such as transportation and routing. When a current is supplied frequently, the heat generated in the contact portion, the deteriorated portion, etc. is greatly accelerated and burns out. In the present invention, when the voltage drop Vr at the time of short circuit exceeds a predetermined allowable value, an abnormal signal is output.
It can be checked whether the cable or connector is normal, and measures such as early replacement can be made. Also, it can be confirmed even when the usable cable length is exceeded.

(5) In the present invention, since a waveform monitor is not particularly required, workability is not impaired since there is no need to install or move a management device in field work.

(6) In the present invention, by using the push-in voltage value V2c, push-in resistance value Rav2, or push-in voltage drop Vr2 to be determined, the data amount can be reduced as compared with the conventional method of managing waveform data by a monitor. A large amount of welding result data can be managed with a small amount.

(7) In the present invention, the stud is pulled up from the material to be welded by using the resistance value Rav2 to be determined and the reference resistance value Rav or the voltage drop Vr2 to be determined and the reference voltage drop Vr. Even if the average value of the welding current when the arc is generated and the average value of the welding current when the stud is pushed into the workpiece are changed, no error occurs.

[Brief description of the drawings]

FIG. 1 is a diagram showing a positional relationship between a steel plate and a steel plate in a case where a steel plate is wavy and a gap (clearance) is generated between the steel plate and the steel plate when the steel plate is disposed on the steel plate.

FIG. 2 is a steel plate / stud positional relationship diagram showing a positional relationship between a steel plate and a stud tip when there is a gap between a steel frame and a steel plate.

FIG. 3A is an output current waveform diagram showing a waveform of an output current Io when a short circuit occurs by a predetermined time t21 after a command for pushing a stud to be a reference into a workpiece to be welded. FIG. 3B is an output terminal voltage waveform diagram showing a waveform of the output terminal voltage Vd when a short circuit is caused by a predetermined time t21 after a command to push a stud to be a reference into a workpiece is set.

FIG. 4A is a load current waveform diagram showing a waveform of an output current Io when a short circuit occurs after a predetermined time t21 after a command for pushing a stud to be determined into a workpiece is issued. FIG. 6B shows the waveform of the output terminal voltage Vd when a short circuit is caused after a command to push the stud to be determined into the workpiece to be welded and later than the predetermined welding voltage detection start time t21 during the short circuit. FIG. 7 is a diagram showing output terminal voltage waveforms.

FIG. 5 is a diagram showing a resistance value Rav to be determined for stud welding;
4 is a flowchart of a stud welding indentation period heat input management method for comparing 2 with a reference resistance value Rav.

FIG. 6 shows a voltage drop V to be determined for stud welding.
It is a flowchart of the pushing-in period heat input management method of the stud welding which compares r2 with the voltage drop Vr used as a reference.

FIG. 7 is a diagram showing an embodiment of a stud welding apparatus for performing the method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Welding power supply device 2 Welding gun 3 Welding control device 5 Current command output circuit 6 D / A converter 7, 8 A / D converter 11 Storage circuit 12 Display circuit 13 Start switch 14 Workpiece material 15 Welding current output circuit 16 Control Cable 17 Secondary cable 18 Stud 21 Steel frame 22 Steel plate CPU Arithmetic processing circuit Da Arc length Dc Gap (clearance) between steel frame 21 and steel plate 22 Dd Push distance De Actual stud tip during penetration welding is pushed into steel frame Penetration amount Dp Thickness of steel sheet Du Pulling distance Ia Main arc current I1a Detection period T during pulling when no short circuit occurs
1 welding current average value / reference welding current average value I2a Detected welding current average value I2c (of studs to be determined) during press-in detection period T2 detection of press-in detection period T2 (of studs to be determined) Welding current average value I1 (t) welding current during raising at time t I2 (t) welding current during pushing at time t IC welding current detection circuit Ic welding current detection signal Io output current / welding current Ip pilot current Is short circuit Current M Movement amount of stud tip P Reference point R (t) Resistance value at time t R (t) Rav Resistance value obtained by dividing welding voltage average value V2a by welding current average value I2a / reference resistance value Rav2 welding voltage average Resistance value obtained by dividing value V2b by welding current average value I2b / resistance value of judgment T1 Detection period during raising T2 Detection period during pushing t0 Pilot current energization start time t1 Main arc current Power supply start time t2c Short-circuiting after welding voltage detection start time t21 during short-circuiting Short-circuiting time t11 Welding voltage detection start time during arcing t12 Welding voltage detection end time during arcing t21 Starting welding voltage detection during short-circuit Time / predetermined time after commanding to push stud into workpiece to be welded t22 Time to end detection of welding voltage during short circuit ts0 Short circuit time during normal welding other than through welding ts1 Short circuit time during through welding; Time during which the tip of the stud moves by the thickness Dp and the gap Dc of the steel sheet ts2 Short-circuit point at which the tip of the stud is pushed into the steel frame at the time of penetration welding V1 (t) Welding voltage during raising of time t V2 (t) Pushing of time t Medium welding voltage V1a Average welding voltage during raising (average welding voltage during detection period T1 when short circuit does not occur (during normal operation)) V2a Average welding voltage during push-in ( The average welding voltage in the detection period T2 during normal operation) / the reference indentation voltage value V2c The average welding voltage value in the detection period T2 when the short circuit occurs after the welding voltage detection start time t21 during the short circuit / the indentation to be determined Voltage value VC Welding voltage detection circuit Vc Welding voltage detection signal Vd Output terminal voltage Vo Load voltage between welding gun and workpiece near welding point Vr Product of welding current average value I1a detected during arc generation and resistance value Rav Voltage drop / reference voltage drop Vr2 Voltage drop of product of welding current average value I1a detected during arc generation and resistance value Rav2 / Voltage drop to be determined

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shoji Harada 1-1-29 Minamimori-cho, Kita-ku, Osaka Inside Daihen Stud Co., Ltd.

Claims (4)

[Claims] In a method for controlling heat input of stud welding,
After raising the stud to be judged from the material to be welded and generating an arc, the stud was pushed into the material to be welded, and the welding voltage average value was detected during short-circuit current conduction when a short circuit occurred, corresponding to the welding voltage average value. A method for controlling heat input during the indentation period of stud welding, in which a value is compared with a predetermined value. 2. A method for controlling heat input of stud welding, comprising:
The first welding voltage is applied during a short-circuit current conduction when a stud to be a reference is pulled up from the material to be welded and an arc is generated, and then the stud is short-circuited by a predetermined time after a command to push the stud into the material to be welded. An average value and a welding current average value are detected, and the first welding voltage average value is set as a reference indentation voltage value. Next, a stud to be determined is pushed into a workpiece to be welded, and the first stud is applied during short-circuit current conduction. The second welding voltage average value is detected when the current having the same average value as the welding current average value is applied, and the second welding voltage average value is determined as the pressing voltage value to be determined. A method for controlling the heat input during the indentation period of stud welding, which compares it with the indentation voltage value used as a reference. 3. The method for controlling heat input of stud welding,
The first welding voltage is applied during a short-circuit current conduction when a stud to be a reference is pulled up from the material to be welded and an arc is generated, and then the stud is short-circuited by a predetermined time after a command to push the stud into the material to be welded. After detecting the average value and the welding current average value, dividing the first welding voltage average value detected during the short-circuit current conduction by the welding current average value to calculate a reference resistance value calculating process. After raising the stud to be determined from the workpiece and generating an arc, the stud is pushed into the workpiece and the second welding voltage average value and the welding current average value are detected during short-circuit current conduction, A determination resistance value calculating step of calculating a resistance value to be determined by dividing the second welding voltage average value detected during the short-circuit current conduction by the welding current average value, and the resistance value to be determined and the reference resistance value Compare with Push period heat input control method for stud welding consisting of resistance value comparison process. 4. A method for controlling heat input of stud welding, comprising:
A command to pull up a stud to be a reference from a material to be welded, detect an average value of a first welding voltage and a mean value of a welding current at which an arc is generated and a short circuit does not occur during occurrence of the arc, and then the stud is pushed into the material to be welded. After the second welding voltage average value and the welding current average value are detected during short-circuit current conduction when short-circuiting occurs by a predetermined time after performing the second welding voltage detection during short-circuit current conduction, A reference voltage drop for calculating a resistance value to be a reference by dividing the average value by a welding current average value, and calculating a voltage drop to be a reference for a product of the resistance value to be the reference and the first welding current average value. In the calculation process, the stud to be determined is pulled up from the material to be welded to generate an arc, and then the stud is pushed into the material to be welded and the third stud is made during the short-circuit current conduction.
After detecting the welding voltage average value and the welding current average value, the third welding voltage average value detected during the short-circuit current conduction is divided by the welding current average value to calculate a resistance value to be determined, and arc generation is performed. A determination voltage drop calculation step of calculating a voltage drop to be determined of a product of the first welding current average value detected during the resistance value and a resistance value to be determined, and a voltage drop to be determined and a voltage drop to be the reference. A method for controlling heat input during the indentation period of stud welding, comprising a voltage drop comparing step of comparing.