JP2022157957A - Arc stud welding device and arc stud welding method - Google Patents

Abstract

To provide an arc stud welding device that is able to improve the quality of welding.SOLUTION: An arc stud welding device includes: a welding gun that pushes and pulls a stud relative to a base material; a power supply device capable of supplying power to the welding gun; a voltage sensor that detects a voltage applied to the welding gun; and a control device that controls the power supply device and the welding gun in a pilot arc period for generating a pilot arc and a main arc period for generating a main arc. When a voltage value obtained from the voltage sensor during the pilot arc period is larger than a first threshold value determined in advance, the control device makes first correction that changes a processing condition for welding in the main arc period, the first correction for suppressing a quantity of heat generated in the base material and the stud, and performs the welding using the processing condition changed by the first correction.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to arc stud welding equipment and arc stud welding methods.

2. Description of the Related Art In an arc stud welding apparatus, there is known a technique of measuring a welding current supplied to an arc stud welding gun and performing feedback control to bring the welding current closer to a target current value (for example, Patent Literature 1). In the conventional technology, feedback control is used to suppress the deterioration of welding quality by eliminating the occurrence of fluctuations in the welding current when it rises and the jumping of the welding current at the plunge point.

JP-A-5-31581

Arc stud welding equipment is required to improve welding quality.

The present disclosure can be implemented as the following forms.

(1) According to one aspect of the present disclosure, an arc stud welding device is provided. This arc stud welding apparatus includes a welding gun that pushes and pulls a stud into and out of a base material, a power supply that can supply power to the welding gun, and a voltage sensor that detects the voltage applied to the welding gun. a pilot arc period for supplying pilot power to the welding gun for generating a pilot arc on the base metal and the stud; and supplying main power to the welding gun for generating a main arc on the base metal and the stud. a control device for controlling the power supply device and the welding gun in a main arc period for supplying a main arc period and a main arc period in which a current larger than the current flowing in the welding gun during the pilot arc period is passed through the welding gun; Prepare. The control device performs a first correction for changing welding processing conditions during the main arc period when a voltage value acquired from the voltage sensor during the pilot arc period is greater than a predetermined first threshold value. , a first correction is performed to suppress the amount of heat generated in the base material and the stud, and welding is performed using the processing conditions changed by the first correction.
According to the arc stud welding device of this form, it is determined whether the voltage value acquired during the pilot arc period is greater than the first threshold value, and the welding processing conditions during the main arc period are changed by the first correction. , the amount of heat generated during welding of the base metal and the stud can be suppressed. Therefore, it is possible to reduce or prevent the application of excessive heat to the base metal and the stud during welding, thereby improving the welding quality.
(2) In the arc stud welding device of the above aspect, the control device may perform the first correction to advance timing of transition to the main arc period.
According to this aspect of the arc stud welding apparatus, by advancing the transition timing to the main arc period, it is possible to shorten the period during which excessive voltage is applied to the stud and the base material during the pilot arc period. As a result, application of excessive heat to the base metal and the stud can be reduced or prevented, and welding quality can be improved.
(3) In the arc stud welding device of the above aspect, the control device may perform the first correction to reduce the target current value of the main electric power.
According to the arc stud welding device of this form, the amount of heat corresponding to the excessive amount of heat given to the stud and the base metal by the voltage higher than the first threshold already applied at the time when the control device acquires the voltage value The main arc period can be reduced and the welding quality can be improved.
(4) In the arc stud welding apparatus of the above aspect, the control device further includes a voltage value in the pilot arc period that is obtained is a predetermined second threshold value that is greater than the first threshold value. If it is greater than or equal to two thresholds, welding of the stud may be stopped.
According to the arc stud welding device of this form, unnecessary processing can be reduced or prevented.
(5) The arc stud welding device of the above aspect may further include a displacement sensor that detects the amount of displacement of the stud with respect to the base material. The control device adjusts welding processing conditions during the main arc period when a difference between the displacement amount and a predetermined reference value is not within a predetermined first range during the pilot arc period. A second correction for changing the heat quantity may be performed.
According to the arc stud welding device of this form, during the pilot arc period, by using the distance between the stud and the base metal to change the processing conditions during the main arc period, excess or deficiency of the amount of heat during welding occurs. can be reduced or prevented.
(6) In the arc stud welding device of the above aspect, when the displacement amount is larger than the reference value in a case where the displacement is not included in the first range, the target current value of the main electric power is set to , the second correction may be performed to change the current value to be smaller than the target current value of the main electric power when the difference between the displacement amount and the reference value is within the first range; If the displacement amount is smaller than the reference value when not included in the range, the difference between the displacement amount and the reference value is included in the first range. The second correction may be performed to change the current value to be larger than the target current value of the main power in the case.
According to the arc stud welding device of this aspect, it is possible to compensate for the excess or deficiency of the amount of heat generated during welding in accordance with the deviation of the amount of displacement of the stud by changing the target current value.
(7) In the arc stud welding device of the above aspect, the control device further includes a predetermined second range in which the difference between the displacement amount and the reference value is wider than the first range. If not within the second range, welding of the stud may be stopped.
According to the arc stud welding device of this form, unnecessary processing can be reduced or prevented.
The present disclosure can also be embodied in various forms other than arc stud welding equipment. For example, it can be realized in the form of an arc stud welding method, a control method of an arc stud welding apparatus, a computer program for realizing the control method, a non-temporary recording medium recording the computer program, or the like.

Explanatory drawing which shows the arc stud welding apparatus as 1st Embodiment. FIG. 4 is a flowchart showing a control routine executed by the control device; FIG. 10 is a flowchart showing a control routine for second correction; The graph which shows typically the target electric current value changed by 2nd correction|amendment. FIG. 4 is a flowchart showing a control routine for first correction; 4 is a graph conceptually showing the target current value changed by the first correction and the shortened pilot arc period; A graph showing a change in voltage during welding by a conventional arc stud welding apparatus as a comparative example. 4 is a graph showing changes in voltage during welding by the arc stud welding apparatus of the present embodiment; FIG. 4 is an explanatory view showing the state of a stud and a base material after welding by a conventional arc stud welding apparatus as a comparative example; Explanatory drawing which shows the state of the stud after welding by the arc stud welding apparatus of this embodiment, and a base material.

A. First embodiment:
FIG. 1 is an explanatory diagram showing an arc stud welding device 100 as a first embodiment of the present disclosure. The arc stud welding device 100 is, for example, a short cycle type welding device. Arc stud welding apparatus 100 includes welder 50 including power supply 54 and controller 52 , and welding gun 70 . The arc stud welding apparatus 100 generates an arc between a base material 90 such as a steel plate or a steel pipe and the stud 80 by attaching a stud 80 such as a bolt or a pin to the welding gun 70 and applying an electric current. . A contact portion between the stud 80 and the base material 90 is melted by an arc, and the melted stud 80 and the base material 90 are welded by being pressurized. Various metal materials such as mild steel, SUS, aluminum, and aluminum alloys can be used as the base material 90 . Arc stud welding apparatus 100 may be a power arc welding apparatus that uses a ferrule.

The control device 52 is a microcomputer that controls the arc stud welding device 100 in an integrated manner, and includes memories such as RAM and ROM, and a CPU. The controller 52 also has a timer (not shown) for measuring time. The control device 52 controls the operation of the welding gun 70, the magnitude of the current applied to the welding gun 70, the energization time, and the like. The memory stores various programs, welding processing conditions, and the like for realizing the functions provided in this embodiment. The welding processing conditions include, for example, a target current value to be applied to the welding gun 70, a target voltage value to be applied to the welding gun 70, an energization period of the pilot arc and the main arc, and a first threshold value, a second threshold value, and a first threshold value, which will be described later. It means one range, second range, and so on. The CPU reads various programs from the memory, develops them on the RAM, and executes them. Some or all of the functions of arc stud welding apparatus 100 may be realized by hardware circuits. The controller 52 may be provided separately from the welder 50 .

The power supply device 54 includes a three-phase AC power supply (not shown) and a rectifier for converting AC to DC. The power supply device 54 and the welding gun 70 are connected by a power supply line CA1, and the power supply device 54 and the base material 90 are connected by a power supply line CA2. Under the control of the control device 52, the power supply device 54 generates pilot electric power for generating a pilot arc on the base material 90 and the stud 80, and main electric power for generating a main arc on the base material 90 and the stud 80. is supplied to the welding gun 70 .

Welding gun 70 pushes stud 80 into and out of base material 90 . The welding gun 70 includes a shaft (not shown) for fixing the stud 80 and a driving mechanism (not shown) for driving the shaft in a direction perpendicular to the base material 90 . Welding gun 70 pulls stud 80 away from base material 90 as indicated by arrow D1 in FIG. 1, and brings stud 80 closer to base material 90 as indicated by arrow D2 in FIG. You can push in any direction. As the drive mechanism, for example, an electromagnetic solenoid type including a spring that biases the shaft toward the base material 90 and a solenoid coil may be used, or a motor drive type in which the shaft is driven by a servomotor or a linear motor may be used. good.

In this embodiment, the arc stud welding device 100 includes a current sensor 56 , a voltage sensor 58 and a displacement sensor 60 . The current sensor 56 is provided on the power supply line CA1. Voltage sensor 58 is provided between power supply line CA1 and power supply line CA2. Current sensor 56 detects the value of current flowing through welding gun 70 , and voltage sensor 58 detects the value of voltage applied to welding gun 70 . A displacement amount sensor 60 is provided in the welding gun 70 and detects the amount of displacement of the stud 80 . The amount of displacement of stud 80 corresponds to the separation distance of stud 80 from base material 90 . In this embodiment, the displacement amount sensor 60 uses a laser displacement meter, and detects the amount of displacement of the stud 80 with a laser beam. The displacement sensor 60 is not limited to a laser displacement meter, and may be a magnetic sensor or the like, or may be various linear encoders such as optical and magnetic linear encoders. Detection results of the current sensor 56 , the voltage sensor 58 , and the displacement sensor 60 are output to the control device 52 .

FIG. 2 is a flow diagram showing a control routine executed by the controller 52. As shown in FIG. The flow shown in FIG. 2 is started by, for example, attaching the base material 90 and the stud 80 to the arc stud welding apparatus 100 and pulling a trigger provided on the welding gun 70 by the worker. This flow is for welding one stud 80 to the base material 90 . For example, when welding the studs 80 to a plurality of positions on the base material 90, this flow is repeated for each position where the studs 80 are to be welded. This flow may be started by pressing the start switch of the arc stud welding apparatus 100 with the base material 90 and the stud 80 attached.

At step S<b>10 , the control device 52 reads setting values corresponding to the types of the stud 80 and the base material 90 . The set values are processing conditions for welding prestored in the memory. Processing conditions for welding include, for example, an energization period during which a pilot arc is generated (hereinafter also referred to as a "pilot arc period"), and a current (hereinafter also referred to as a "pilot current") to be passed during the pilot arc period. , the target voltage value of the voltage applied during the pilot arc period (hereinafter also referred to as "pilot voltage"), and the period for generating the main arc (hereinafter also referred to as "main arc period"). energization period, the target current value of the current flowing during the main arc period (hereinafter also referred to as "main current"), and the target voltage of the voltage applied during the main arc period (hereinafter also referred to as "main voltage") value and . The pilot current is on the order of 10-50 A for sustaining the arc column between stud 80 and base metal 90 . The main current is about 200-2000 A for generating a main arc between stud 80 and base material 90 .

In step S<b>20 , controller 52 controls power supply 54 to apply a pilot current to stud 80 and base material 90 . Specifically, controller 52 controls the drive mechanism of welding gun 70 to press the tip of stud 80 attached to welding gun 70 against the surface of base material 90 . When the stud 80 is pressed against the base material 90, the control device 52 controls the power supply device 54 to apply the pilot current to the stud 80 and the base material 90 according to the target current value of the pilot current. Controller 52 drives the drive mechanism of welding gun 70 to pull stud 80 up from base material 90 , thereby generating a pilot arc between stud 80 and base material 90 .

In step S<b>30 , the control device 52 acquires the displacement amount La of the stud 80 from the displacement amount sensor 60 . The amount of displacement La of stud 80 corresponds to the distance by which stud 80 is lifted from base material 90 in step S20.

In step S40, the control device 52 confirms the amount of deviation of the lifted distance of the stud 80. As shown in FIG. Specifically, the control device 52 determines whether the difference between the obtained displacement amount La and the reference displacement Lm as a predetermined reference value is included in the first range, and whether the difference is included in the second range. Check whether or not The reference displacement Lm, the first range, and the second range are pre-stored in the memory of the controller 52 . The reference displacement Lm is a target value for the amount of displacement of the stud 80 during welding, and corresponds to a target value for the lifting distance of the stud 80 from the base material 90 . A deviation in the lift amount of the stud 80 may occur due to, for example, a mechanical error caused by the welding gun 70 or the like.

The first range can be set, for example, in the range of -L1 or more and L1 or less. The second range can be set, for example, within a range of -L2 or more and L2 or less. The second range is a range wider than the first range and satisfies L2>L1. The first range and the second range, that is, L1 and L2, are set values that are set in advance so that sufficient welding quality can be obtained by the main arc after the second correction, which will be described later. L1 is the lower limit as the absolute value of the deviation of the amount of pulling up the stud 80 that is allowed to obtain sufficient welding quality by the main arc after the second correction, and L2 is the upper limit as the absolute value of the deviation. value. If the absolute value of the difference in the amount of pulling up the stud 80 is greater than L1 and equal to or less than L2, sufficient welding quality can be obtained by the main arc after the second correction. Even with the main arc, sufficient welding quality may not be obtained. L1 and L2 can be obtained experimentally in advance by using the corresponding relationship between the magnitude of the main current for each displacement amount La and the welding quality after the main arc. In this embodiment, L1 is set at 0.5 mm and L2 is set at 1.0 mm. In the present embodiment, the upper limit of the first range is L1, the lower limit is -L1, the absolute values are both L1, and the absolute values of the upper limit and the lower limit of the second range are Although both are identical at L2, the upper limit value and the lower limit value of the first range may be set to different values, and the upper limit value and the lower limit value of the second range may be set to different values. .

If the difference between the obtained displacement amount La and the reference displacement Lm is within the first range, the control device 52 proceeds to step S60, and if it is not within the first range but within the second range, goes to step S50, and if not included in the second range, goes to step S120. In step S120, control device 52 determines that there is an abnormality, controls power supply device 54 to stop output, and ends welding. In step S130, the control device 52 uses, for example, a display device, a speaker, or the like of the arc stud welding device 100 to notify the operator of the determination result of the presence of abnormality, and ends this flow.

In step S50, the control device 52 performs a second correction. In the second correction, as will be described later, the welding processing conditions are changed during the main arc period. In this embodiment, the second correction changes the target current value of the main current and the target voltage value of the pilot voltage. After performing the second correction, the control device 52 proceeds to step S60.

At step S60, the controller 52 acquires the voltage value during the pilot arc period from the voltage sensor 58. FIG. In the present embodiment, the control device 52 uses the voltage values acquired from the voltage sensor 58 to calculate the average value of the voltage per unit time such as 1 millisecond, and acquires it as the voltage value Va. The voltage sensor 58 may calculate the average value of the voltage per unit time and output it to the control device 52 .

In step S70, the control device 52 confirms the amount of deviation of the effective voltage from the target voltage value. Specifically, the control device 52 determines whether the difference between the acquired voltage value Va and the target voltage value Vm of the pilot voltage in the pilot arc period is equal to or less than the first threshold value V1, and determines whether or not the difference is less than the second threshold value V2. It is determined whether or not. The second threshold V2 is a voltage value higher than the first threshold V1, where V2>V1. The target voltage value Vm, the first threshold value V1, and the second threshold value V2 are stored in advance in the memory of the controller 52. FIG.

The first threshold value V1 is a setting value for obtaining sufficient welding quality by the main arc under normal processing conditions, and the second threshold value V2 is a setting value for obtaining sufficient welding quality by the main arc under processing conditions after the first correction, which will be described later. This is the set value for obtaining a sufficient value. If the voltage value Va is larger than the first threshold value V1 and smaller than the second threshold value V2, the main arc can obtain sufficient welding quality by performing the first correction, and if the voltage value Va exceeds the second threshold value V2, Even with the main arc after the first correction, sufficient welding quality may not be obtained. For example, if foreign matter such as oil is present on the surface of base material 90, electrical resistance between base material 90 and stud 80 may increase. Control device 52 increases the power supplied from power supply device 54 in order to raise the pilot current to the target current value. As a result, the pilot voltage can be raised. In this embodiment, the first threshold V1 and the second threshold V2 function as thresholds for detecting foreign matter on the surface of the base material 90 using the pilot voltage. The first threshold value V1 and the second threshold value V2 can be experimentally obtained in advance by obtaining the correspondence relationship between the pilot voltage and the welding quality after the main arc, for example, using the base material 90 having foreign matter on the surface. can be done. The first threshold value V1 and the second threshold value V2 may be obtained using the correspondence relationship between the amount of foreign matter adhering to the surface of the base material 90 and the pilot voltage. In this embodiment, the first threshold V1 is set at 5V, and the second threshold V2 is set at 10V. The first threshold V1 is not limited to 5V, and may be set at 2.5V, 3V, 4V, or any other voltage such as 6V, 7.5V, 10V, or 15V. The second threshold V2 is not limited to 10V, and may be set to 5V, 6V, 7.5V, 15V, 20V, or the like, and may be set to any voltage that satisfies V2>V1. When the difference between the acquired voltage value Va and the target voltage value Vm is equal to or less than the first threshold value V1, the control device 52 proceeds to step S100, where the difference is greater than the first threshold value V1 and less than the second threshold value V2. If so, the process moves to step S80, and if it is equal to or greater than the second threshold value V2, the process moves to step S120.

In step S100, the control device 52 starts the main arc with the lapse of the energization period in the preset pilot arc period as a start condition. Specifically, controller 52 controls power supply 54 to apply a main current to stud 80 and base material 90 to start a main arc. When the second correction is performed in step S50 described above, the control device 52 starts the main arc by causing the main current to flow based on the target setting value after the change by the second correction. The tip of the stud 80 and the base material 90 where the arc discharge is performed are melted by the heat of the arc discharge. After a predetermined period of time has elapsed from the start of the arc discharge, the controller 52 controls the drive mechanism of the welding gun 70 to push the stud 80 into the surface of the base material 90, thereby joining the stud 80 and the base material 90 together. be In step S110, the control device 52 controls the power supply device 54 to stop the output and finish the welding when the energization period of the predetermined main arc period elapses.

In step S80, the control device 52 confirms whether or not the amount of deviation of the lifting distance of the stud 80 is within the first range. In this embodiment, the control device 52 uses the determination result in step S40 to check whether the difference between the displacement amount La and the reference displacement Lm is included in the first range. If the difference between the displacement amount La and the reference displacement Lm is within the first range, that is, if the determination result of step S40 is |La−Lm|≦L1, the process proceeds to step S90.

In step S80, if the difference between the displacement amount La and the reference displacement Lm is not included in the first range, that is, if the determination result in step S40 is L1<|La−Lm|≦L2, The process proceeds to step S120 to finish welding. Here, in step S80, when the difference between the displacement amount La and the reference displacement Lm is not included in the first range, the voltage value Va of the execution voltage exceeds the first threshold value V1 and the stud 80 is not included in the first range. In this embodiment, in this case, processing to end welding is performed in consideration of the possibility that sufficient welding quality cannot be obtained by the main arc. That is, in the present embodiment, both the second correction in step S50 and the first correction in step S90, which will be described later, are not performed. However, if the arc stud welding apparatus 100 can obtain sufficient welding quality by the main arc after the first correction even under this condition, step S80 is omitted and step S70 is directly transferred to step S90. good too.

In step S90, the control device 52 performs a first correction. In the first correction, as will be described later, the target current value of the main current is changed and the energization period in the pilot arc period is shortened. In step S102, the control device 52 controls the power supply device 54 to start the main arc based on the target current value after the first correction. In this embodiment, as will be described later, the control device 52 starts the main arc immediately after the process of step S90. After a predetermined energization period has passed since the start of the main arc, the controller 52 controls the driving mechanism of the welding gun 70 to join the stud 80 and the base material 90 together. In step S112, the power supply unit 54 is controlled to stop the output and the welding is finished as the predetermined energization period in the main arc period elapses.

Details of the second correction will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 is a flow chart showing a control routine for the second correction. At step S52, the controller 52 changes the target current value of the main current. In this embodiment, the target current value Im2 after change by the second correction is calculated using the following formula (1).
Im2=Im1·{1−k1·(La−Lm)/L1} Expression (1)
Im1: Target current value of the main current in normal operation k1: Coefficient The target current value Im1 corresponds to the current value supplied to the welding gun 70 when the difference between the displacement amount La and the reference displacement Lm is included in the first range. do. The coefficient k1 is a coefficient that defines the correction amount of the target current value of the main current. The coefficient k1 can be obtained experimentally using, for example, the correspondence between the current value of the main current for each amount of displacement of the stud 80 and the welding quality after the main arc. In this embodiment, k1 is set to 0.05. The coefficient k1 is not limited to 0.05, and may be set to any numerical value such as 0.01, 0.025, 0.1, 0.15, 0.2.

As shown in equation (1), in the present embodiment, the coefficient k1 is further multiplied by the equation (La-Lm)/L1 to calculate the second correction value. The formula (La−Lm)/L1 is a coefficient based on the deviation amount of the displacement amount La. When the deviation amount of the displacement amount La is large with respect to the reference displacement Lm, the correction amount of the second correction value is set to be larger than when the deviation amount of the displacement amount La is small. With this configuration, it is possible to set the target current value Im2 of the main current corresponding to the magnitude of the detected deviation amount of the displacement La of the stud 80, thereby further improving the welding quality by the main arc. can.

At step S54, the controller 52 changes the target voltage value during the pilot arc. In this embodiment, the target voltage value Vp2 after the change by the second correction is calculated using the following formula (2).
Vp2=Vp1+k2·(La−Lm) Expression (2)
Vp1: target voltage value of pilot voltage in normal operation k2: coefficient The target voltage value Vp1 corresponds to the voltage value applied when the difference between the displacement amount La and the reference displacement Lm is included in the first range. The coefficient k2 is a coefficient that defines the correction amount of the target voltage value of the pilot voltage. The coefficient k2 can be obtained experimentally using, for example, the correspondence between the amount of displacement of the stud 80 and the voltage value of the pilot voltage. In this embodiment, k2 is set to 3.8. The coefficient k2 is not limited to 3.8, and may be set to any numerical value such as 2.0, 3.0, 4.0, 5.0.

If the stud 80 is further from the base material 90, the power output from the power supply 54 may be greater, and if the stud 80 is closer to the base material 90, the power output from the power supply 54 may be less. Therefore, in the present embodiment, by changing the target voltage value of the pilot voltage according to the deviation amount of the displacement amount of the stud 80, the output voltage after the change based on the deviation amount of the displacement amount of the stud 80 is detected as an abnormal value. to be suppressed.

Details of the process of changing the target current value of the main current executed in step S52 will be described with reference to FIG. FIG. 4 is a graph schematically showing the target current value changed by the second correction. FIG. 4 shows a graph conceptually showing target current values in the pilot arc period and the main arc period. The horizontal axis of the graph in FIG. 4 represents time (milliseconds), and the vertical axis represents current value (A). Note that the horizontal time axis is also common in FIGS. 6 to 8 described later. The period from time T1 to time T2 is the pilot arc period, and the current value Ip is the target current value of the pilot current. The period from time T2 to time T3 is the main arc period, and the current value Im1 is the target current value of the main current during normal operation, that is, the target current value of the main current when the second correction is not performed. A solid line G1 shows an example of a change in the target current value of the main current during normal operation. A dashed line G2 and a dashed line G3 respectively indicate an example of the target current value when executing the second correction. The current values Im21 and Im22 are examples of the target current value Im2 after the second correction. Specifically, the current value Im21 indicates an example of the minimum value of the target current value Im2 after the second correction, and the current value Im22 indicates an example of the maximum value of the target current value Im2 after the second correction. . Note that the graphs of FIGS. 4 and 6 conceptually show changes in current values for easy understanding of the technology, and do not accurately show the absolute values of each current value.

A dashed line G2 conceptually shows an example of a change in the main current due to the second correction executed when the difference between the displacement amount La of the stud 80 and the reference displacement Lm is positive. The case where the difference between the displacement amount La and the reference displacement Lm is positive is when the displacement amount La is larger than the reference displacement Lm, that is, when the stud 80 is positioned farther from the base material 90 than normal. corresponds to In the present embodiment, when the difference between the displacement amount La and the reference displacement Lm is positive, the target current value under normal conditions is set to the target current value Im21 shown in FIG. Correction is made so that the target current value becomes smaller than Im1. Here, when the stud 80 is farther from the base material 90 than usual, the main current can be lower than usual. Therefore, the output power from the power supply device 54 can be larger than normal in order to raise the current value to the target current value. As a result, the main voltage rises, and the amount of heat generated during welding can be excessive. In this embodiment, when the difference between the displacement amount La and the reference displacement Lm is positive, the second correction is performed to reduce the target current value of the main current, thereby preventing the amount of heat generated during welding from becoming excessive. reduce or prevent

A dashed line G3 conceptually shows an example of a change in the main current due to the second correction executed when the difference between the displacement amount La of the stud 80 and the reference displacement Lm becomes negative. The case where the difference between the displacement amount La and the reference displacement Lm is negative corresponds to the case where the displacement amount La is smaller than the reference displacement Lm, that is, the case where the position of the stud 80 is closer to the base material 90 than normal. do. In the present embodiment, when the difference between the displacement amount La and the reference displacement Lm is negative, the target current value under normal conditions is set to the target current value Im22 shown in FIG. The target current value is corrected to be larger than Im1. Here, when the stud 80 is closer to the base material 90 than normal, the main current may increase more than normal. Therefore, the output power from the power supply device 54 can be smaller than normal in order to reduce the current value to the target current value. As a result, the main voltage is reduced, and the amount of heat during welding can be lower than usual. In this embodiment, when the difference between the displacement amount La and the reference displacement Lm is negative, the second correction is performed to increase the target current value of the main current, thereby preventing the shortage of heat during welding. reduced or prevented.

The details of the first correction will be described with reference to FIGS. 5 to 8. FIG. FIG. 5 is a flow chart showing the control routine for the first correction. In step S92, the controller 52 changes the target current value of the main current. In this embodiment, the target current value Im3 after correction by the first correction is calculated using the following formula (3).
Im3=k3·Im1 Expression (3)
k3: Coefficient The coefficient k3 is a coefficient for adjusting the amount of heat given to the stud 80 and the base material 90 . Here, when an excessive voltage exceeding the first threshold value V1 is applied during the pilot arc period, the stud 80 and the base material 90 are given a larger amount of heat than normal. The current value of the main current is reduced by using the coefficient k3 in order to reduce the amount of heat corresponding to the excessive amount of heat given to the base material 90 and the stud 80 . The coefficient k3 uses, for example, the correspondence between the current value of the main current when an effective voltage greater than the first threshold value V1 is applied to the base metal 90 and the stud 80 during the pilot arc period, and the welding quality after the main arc. can be obtained experimentally in advance. In this embodiment, k3 is set to 0.95. The coefficient k3 is not limited to 0.95, and may be set to any numerical value such as 0.975, 0.925, 0.90, 0.85, 0.80, 0.70. Even if the measured voltage exceeds the first threshold value V1 during the pilot arc period, if sufficient welding quality can be obtained by performing only the processing of step S94 described later, step S92 is omitted. can do.

In step S94, the control device 52 shortens the pilot arc period more than the normal time, and advances the transition timing to the main arc period. The earlier the transition timing to the main arc period, the better. In this embodiment, after performing the process of changing the target current value in step S92, the control device 52 immediately shifts to the main arc period regardless of the timing result of the pilot arc period. Even if the measured voltage exceeds the first threshold value V1 during the pilot arc period, if sufficient welding quality can be obtained without shortening the pilot arc period, only step S92 is executed. and step S94 can be omitted.

FIG. 6 is a graph conceptually showing the target current value changed by the first correction and the pilot arc period shortened by the first correction. The horizontal axis of the graph in FIG. 6 represents time (milliseconds), and the vertical axis represents current value (A). A solid line G1 indicates an example of the target current value at normal times, that is, the target current value when the first correction is not performed. A dashed line G4 indicates an example of the target current value after the first correction. The current value Im1 is the target current value of the main current during normal operation.

A current value Im3 indicates a target current value of the main current after the first correction. The target current value Im3 is set smaller than the normal target current value Im1 according to the above equation (3). In this embodiment, the target current value Im3 is 5% smaller than the normal target current value Im1.

Time T4 indicates the start timing of the main arc period after the first correction, and time T2 indicates the start timing of the normal main arc period. As shown in FIG. 6, time T4 is closer to time T1, which is the start timing of the pilot arc period, than time T2, and the start timing of the main arc period is shorter than normal. The length of the main arc period before the first correction and the length of the main arc period after the first correction are substantially the same. Therefore, time T5, which is the end timing of the main arc period after the second correction, is earlier than time T3, which is the end timing of the main arc period in the normal state, by the difference between time T4 and time T2.

FIG. 7 is a graph showing changes in voltage during welding by a conventional arc stud welding apparatus as a comparative example. In FIG. 7, a solid line G5 indicates an example of the target voltage value, and a broken line GR indicates an example of the actual voltage value obtained by the voltage sensor 58. In FIG. More specifically, the dashed line GR is an example of a case where the measured voltage exceeds the first threshold V1 during the pilot arc period. A dashed line GR corresponds to an example of a voltage value when processing a base material 90 having foreign matter attached to its surface. Note that the displacement amount La of the stud 80 is included in the first range. As indicated by the dashed line GR, the measured voltage VR at time T7 exceeds the first threshold V1. As shown in FIG. 7, in the conventional arc stud welding apparatus, the measured voltage indicated by the dashed line GR continues to be higher than the target voltage value Vm until time T2 when the main arc period shifts. This is based on the fact that the control device 52 executes constant current control during the pilot arc period and the target current value is not changed during the pilot arc period.

FIG. 8 is a graph showing changes in voltage during welding by the arc stud welding apparatus 100 of this embodiment. In FIG. 8, a solid line G5 indicates an example of the target voltage value, and a broken line G6 indicates an example of the actual voltage value obtained by the voltage sensor 58. In FIG. More specifically, the dashed line G6 is an example of the case where the measured value of the voltage exceeds the first threshold value V1 during the pilot arc period, and is an example of the case of processing the base material 90 with foreign matter adhering to the surface. Equivalent to. Note that the displacement amount La of the stud 80 is included in the first range.

As indicated by the dashed line G6, the measured voltage Va1 at time T8 exceeds the first threshold value V1. Therefore, the control device 52 immediately shifts to the main arc period after performing the process of changing the target current value Im1 of the main current to the target current value Im3. Therefore, as shown in FIG. 8, time T4, which is the transition timing to the main arc period, is timing immediately after time T8. In the arc stud welding apparatus 100 of the present embodiment, in order to immediately shift to the main arc period, compared to the conventional example indicated by the broken line GR in FIG. can be shortened.

The effect produced by the arc stud welding device 100 of this embodiment will be described with reference to FIGS. 9 and 10. FIG. FIG. 9 is an explanatory diagram showing the state of a stud 80 and a base material 90 after welding by a conventional arc stud welding apparatus as a comparative example. FIG. 10 is an explanatory diagram showing the state of the stud 80 and the base material 90 after welding by the arc stud welding apparatus 100 of this embodiment.

According to the conventional arc stud welding apparatus, for example, as indicated by the dashed line GR in FIG. applied. Therefore, the amount of heat applied to stud 80 and base material 90 increases. As a result, as shown in FIG. 9, the volume of the melted portion 82 melted during welding can be larger than usual. As a result, as shown in FIG. 9 as a protruding portion F1, the melted portion 82 penetrates the back surface of the base material 90, which is a so-called strike-through problem.

According to the arc stud welding apparatus 100 of the present embodiment, for example, as indicated by the broken line G6 in FIG. 8, when the measured voltage Va1 higher than the first threshold value V1 is detected in the pilot arc period, immediately Transition to the main arc period. As a result, the period during which the voltage higher than the first threshold value V1 is applied to the stud 80 and the base material 90 is shortened. Therefore, for example, even when the stud 80 is welded to the base material 90 having foreign matter on its surface, it is possible to reduce or suppress the application of excessive heat to the stud 80 and the base material 90 during the pilot arc period. can. As a result, as shown in FIG. 10, the volume of the fusion zone 82 can be reduced compared to the volume of the fusion zone 82 that occurs in conventional arc stud welding equipment, reducing or preventing deterioration in weld quality. be able to.

Further, according to the arc stud welding apparatus 100 of the present embodiment, the target current value Im3 in the main arc period is further reduced to the target current value Im1 in the normal time by the first correction, as indicated by the dashed line G4 in FIG. 6, for example. is changed to a smaller current value than As a result, the amount of heat applied to the stud 80 and the base material 90 by the high measured voltage Va1 already applied during the period from when the control device 52 obtains the measured voltage Va1 to the transition to the main arc period corresponds to the excessive amount of heat. The amount of heat can be reduced during the main arc period. For example, by making the total amount of heat during welding after the first correction substantially equal to the total amount of heat under normal conditions, the volume of the fusion zone 82 can be substantially equal to that under normal conditions. As a result, as shown in FIG. 10, the volume of the melted portion 82 becomes substantially the same as that in normal operation, which is smaller than the volume of the melted portion 82 generated in the conventional arc stud welding apparatus, and the welding quality deteriorates. can be reduced or prevented.

As described above, according to the arc stud welding apparatus 100 of the present embodiment, the control device 52 acquires the voltage value Va of the pilot voltage from the voltage sensor 58 during the pilot arc period, and the voltage of the acquired pilot voltage When the value Va is greater than a predetermined first threshold value V1, the amount of heat generated during welding of the base material 90 and the stud 80 is suppressed by the first correction that corrects the processing conditions during the main arc period. Whether or not the voltage value Va in the pilot arc period is greater than the first threshold value V1 determines whether or not there is an abnormality in the base material 90 before shifting to the main arc period, and corrects the machining conditions in the main arc period. Therefore, it is possible to reduce or prevent the application of excessive heat to the base material 90 and the stud 80 during welding. Therefore, it is possible to reduce or prevent the occurrence of problems such as strike-through of the base material 90 and improve the welding quality.

According to the arc stud welding apparatus 100 of the present embodiment, when a voltage higher than the first threshold value V1 is detected during the pilot arc period, the control device 52 executes the first correction to shift to the main arc period. Accelerate transition timing. By advancing the transition timing to the main arc period, the period in which the voltage higher than the first threshold value V1 is applied to the stud 80 and the base material 90 can be shortened, and the base material 90 and the stud 80 are heated excessively. Weld quality can be improved by reducing or preventing the application of heat.

According to the arc stud welding apparatus 100 of the present embodiment, when a voltage higher than the first threshold value V1 is detected in the pilot arc period, the control device 52 performs the first correction to set the target current of the main current. Decrease value. The amount of heat corresponding to the excessive amount of heat given to the stud 80 and the base material 90 by the high actual voltage Va1 already applied during the period from when the control device 52 obtains the actual voltage Va1 to the transition to the main arc period is reduced to the main arc period. can be reduced during the arc period. Therefore, for example, by making the total amount of heat during welding substantially equal to that during normal welding, it is possible to reduce or prevent the deterioration of welding quality.

According to the arc stud welding apparatus 100 of the present embodiment, the control device 52 further controls the welding of the stud 80 when the voltage value Va of the pilot power is equal to or greater than the second threshold value V2 larger than the first threshold value V1. to stop During the pilot arc period, if it is determined that the surface of the base material 90 does not achieve welding quality even after the first correction, welding can be stopped to reduce or prevent unnecessary processing.

According to the arc stud welding apparatus 100 of the present embodiment, the control device 52 determines that the difference between the displacement amount La and the predetermined reference displacement Lm is not included in the predetermined first range during the pilot arc period. In some cases, the amount of heat given to the stud 80 and the base material 90 is adjusted by a second correction that changes the machining conditions during the main arc period. Using the amount of displacement of the stud 80, estimate the excess or deficiency of the amount of heat generated during welding according to the distance between the stud 80 and the base material 90 during the pilot arc period, and change the processing conditions during the main arc period. Thus, it is possible to reduce or prevent the occurrence of excess or deficiency of the amount of heat during welding.

According to the arc stud welding apparatus 100 of the present embodiment, the control device 52 determines that the difference between the displacement amount La and the predetermined reference displacement Lm is not included in the predetermined first range during the pilot arc period. , when the displacement amount La is greater than the reference displacement Lm, the second correction changes the target current value Im1 of the main electric power to a target current value Im21 smaller than the target current value Im1 of the main electric power under normal conditions. I do. If the displacement amount La is smaller than the reference value, a second correction is performed to change the target current value Im1 of the main electric power to a target current value Im22 that is larger than the target current value Im1 under normal conditions. Therefore, it is possible to compensate for the excess or deficiency of the amount of heat generated during welding according to the deviation of the amount of displacement of the stud 80 by changing the target current value Im1.

According to the arc stud welding apparatus 100 of the present embodiment, the control device 52 further controls the difference between the displacement amount La and the predetermined reference value when it is not included in the second range wider than the first range. stops the welding of stud 80. During the pilot arc period, when it is determined that the surface of the base material 90 cannot be welded to the desired welding quality even after the second correction, welding can be stopped to reduce or prevent unnecessary processing.

B. Other embodiments:
(B1) In the first embodiment, the control device 52 performs both the first correction and the second correction. On the other hand, for example, when the mechanical error of the stud 80 due to the drive mechanism of the welding gun 70 is sufficiently small, or when the distance between the stud 80 and the base material 90 has a sufficiently small effect on welding quality, For example, steps S40 and S50 may be omitted, and only the first correction may be performed without performing the second correction. In this case, the controller 52 may proceed to step S60 after executing step S30. Further, step S80 may be omitted while omitting the second correction.

(B2) In the first embodiment, the controller 52 stops welding the stud 80 when the difference between the obtained displacement amount La and the reference displacement Lm is not within the second range in step S40. Let On the other hand, even if the difference between the displacement amount La and the reference displacement Lm is not included in the second range, the welding quality after the main arc is sufficient, such as by performing additional machining after the main arc. It is not necessary to stop the welding of the stud 80 if it is possible to do so. The same applies to step S80.

The present disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from the scope of the present disclosure. For example, the technical features of the embodiments corresponding to the technical features in each form described in the outline of the invention are used to solve some or all of the above problems, or Alternatively, replacements and combinations can be made as appropriate to achieve all. Also, if the technical features are not described as essential in this specification, they can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 50... Welding machine, 52... Control device, 54... Power supply device, 56... Current sensor, 58... Voltage sensor, 60... Displacement amount sensor, 70... Welding gun, 80... Stud, 82... Fusion zone, 90... Base metal, 100... Arc stud welding device, CA1, CA2... Power supply line, F1... Protruding part, Im1, Im2, Im21, Im22, Im3, Ip... Target current value, La... Displacement amount, Lm... Reference displacement, V1... First Threshold, V2... Second threshold, Va1, VR... Measured voltage, Va... Voltage value, Vm... Target voltage value, Vp1, Vp2... Target voltage value

Claims (8)

An arc stud welding device,
a welding gun for pushing and pulling the stud against the base material;
a power supply device capable of supplying power to the welding gun;
a voltage sensor for detecting the voltage applied to the welding gun;
a pilot arc period for supplying the welding gun with a pilot electric power for generating a pilot arc on the base material and the stud; and supplying the welding gun with main electric power for generating a main arc on the base material and the stud. a control device for controlling the power supply device and the welding gun during a main arc period in which a current larger than the current flowing in the welding gun during the pilot arc period is passed through the welding gun; prepared,
The control device is
When the voltage value obtained from the voltage sensor during the pilot arc period is greater than a predetermined first threshold,
A first correction for changing the welding processing conditions during the main arc period, the first correction for suppressing the amount of heat generated in the base metal and the stud,
Welding using the processing conditions changed by the first correction,
Arc stud welding equipment. The arc stud welding device according to claim 1,
The control device performs the first correction to advance the timing of transition to the main arc period.
Arc stud welding equipment. The arc stud welding device according to claim 1 or 2,
The control device performs the first correction to reduce the target current value of the main power.
Arc stud welding equipment. The arc stud welding device according to any one of claims 1 to 3,
Further, when the obtained voltage value during the pilot arc period is equal to or greater than a second threshold value that is a predetermined second threshold value that is larger than the first threshold value, the stud is to stop welding,
Arc stud welding equipment. The arc stud welding device according to any one of claims 1 to 4,
Furthermore, a displacement amount sensor that detects the amount of displacement of the stud with respect to the base material,
The control device is
In the pilot arc period, when the difference between the displacement amount and a predetermined reference value is not included in a predetermined first range,
A second correction for changing the welding processing conditions during the main arc period, wherein the second correction is performed for adjusting the heat quantity,
Arc stud welding equipment. The arc stud welding device according to claim 5,
The control device is
When not included in the first range, when the displacement amount is greater than the reference value, the target current value of the main electric power is set to the difference between the displacement amount and the reference value within the first range. Perform the second correction to change the current value to a smaller current value than the target current value of the main power in the case included in
When not included in the first range, if the displacement amount is smaller than the reference value, the target current value of the main electric power is set so that the difference between the displacement amount and the reference value is within the first range. Perform the second correction to change the current value to a current value larger than the target current value of the main power in the case included in
Arc stud welding equipment. The arc stud welding device according to claim 5 or claim 6,
If the difference between the displacement amount and the reference value is not included in a predetermined second range that is wider than the first range, the control device further controls the to stop the welding of studs,
Arc stud welding equipment. An arc stud welding method comprising:
obtaining the voltage value of the pilot power supplied to the base metal and the stud during a pilot arc period for supplying the base metal and the stud with the pilot power for generating the pilot arc in the base metal and the stud;
When the obtained voltage value is greater than a predetermined first threshold,
A main arc period for supplying main electric power to the base metal and the stud for generating a main arc in the base metal and the stud, the current being larger than the current flowing through the base metal and the stud during the pilot arc period A first correction for changing the welding processing conditions during the main arc period in which the current is passed through the base metal and the stud, the first correction for suppressing the amount of heat generated when the base metal and the stud are welded. ,
Welding using the processing conditions changed by the first correction,
Arc stud welding method.

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