JPH0639553A - Controller for stud welding machine - Google Patents

Abstract

PURPOSE:To provide the stud welding machine provided with the controller to control a welding current supplied to a welding gun in accordance with timing of pressure welding of a stud. CONSTITUTION:The welding machine is constituted of the welding gun 4, a power source 5 and the controller 6 and a voltage detector 7 between the stud 3 and base metal 2, a setting device 10 of a main arc duration time and an alarm device 25 are provided on the controller. The controller 6 controls so as to supply electric power to form a pilot arc and a main arc to the welding gun 4, controls the welding gun 4 so as to weld the stud 3 to the base metal 2 with pressure in the specified time and stops the supply of electric power according to a pressure welding signal from the voltage detector 7. The controller 6 controls the power source so as to lower electric power gradually after the lapse of a main arc duration time by the setting device 10 and surely controls timing when the welding gun 4 welds the stud 3 to the base metal 2 with pressure while the current is dropped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stud welder, and more particularly, to a device for appropriately controlling the timing at which a welding gun presses a stud against a base metal and the timing at which current is supplied to the welder.

[0002]

2. Description of the Related Art A welding gun that holds a stud so that a welding tip can contact the base metal, a power supply connected to the welding gun so as to supply a predetermined electric power between the stud and the base metal, and a power supply. Connected to the welding gun and controlling the electric power that forms the pilot arc and the subsequent main arc between the stud and the base metal to be supplied from the power supply to the welding gun. A stud welder consisting of a control device for controlling a welding gun so as to press-contact at a predetermined time is well known, and this stud welder is used for welding a stud to a vehicle body or the like, and an insulating material or the like is used for the stud. It can be attached to the vehicle body using a clip that locks to.

[0003]

In such a stud welding machine, the timing at which the welding gun presses the stud against the base metal and the timing at which the electric current is supplied to the welding machine are sometimes not properly controlled. As a power source for supplying electric power to a welding gun of a conventional stud welding machine, a capacitor discharge type power source and a transformer rectification type power source are known. In the capacitor discharge type power supply, the magnitude and time of the power supplied to the welding gun are determined by the capacity and impedance of the capacitor, and it is impossible to adjust the timing of welding of the stud and the welding current waveform in synchronization. Even in the transformer rectification type power supply, the power is determined by the capacity and impedance of the transformer and the phase control of the thyristor for rectification. Even in this power supply, the timing of the stud pressure contact and the welding current waveform could not be adjusted in synchronization. .

As is well known, in a stud welding machine using a capacitor discharge type power source, the stud is a base metal at a portion descending from the peak of the welding current waveform and up to about 1/3 of that portion. It is preferable to press it against. Further, in the stud welding machine using the transformer rectification type power source, it is preferable to press-contact at a portion which is descended from the apex of the last welding current waveform and is about a half thereof. However, since these timings are determined by the power supply method as described above, the characteristics differ from device to device. In addition, the timing may shift due to changes over time, and it is necessary to adjust the welding current and the timing of the pressure welding of the stud to the base metal for each machine. Could not be maintained properly.

Accordingly, it is an object of the present invention to provide a stud welding machine provided with a control device for controlling the welding current supplied to the welding gun in accordance with the timing of stud pressure welding.

[0006]

In order to achieve such an object, according to the present invention, a welding gun for holding a stud so that a welding tip can be brought into contact with a base material, and a predetermined gap between the stud and the base material. A power source connected to the welding gun to supply the power of the welding power source and a power source connected to the power source and the welding gun to form a pilot arc and a subsequent main arc between the stud and the base metal. A stud welding machine comprising a control device for controlling the welding gun so that the stud is supplied to the gun and pressed against the base material at a predetermined time. Detecting means for detecting a voltage between the stud and the base material and outputting a signal indicating that the stud is pressed against the base material, and the control device receives a pressure contact signal from the detecting means and then welds from a power source. Moth Stud welding machine, wherein there is provided to stop the supply of power to. This allows
After confirming that the stud is pressed against the base material, the current is cut off, so that the timing difference between the pressure contact and the current supply can be prevented.

Further, according to the present invention, in the above-mentioned stud welding machine, the controller provided with means for setting the duration of the main arc supplies the electric current to the welding gun after the duration. The power supply is controlled so that the welding gun gradually presses the stud against the base metal. It is also possible to appropriately control the timing of stud pressure contact.

Further, according to the present invention, in the above stud welding machine, the control device is provided with means for issuing an alarm when the time for pressing the stud against the base material exceeds a predetermined time length. When the alarm is generated, the stud that controls the power supply to stop the power supply from the power supply after a certain period of time after the duration of the main arc has elapsed, apart from the alarm generation. A welding machine is provided to prevent defects such as punching of the base metal due to excessive melting. In this case, if the time during which the stud is pressed against the base metal does not reach the predetermined time, the control device activates the alarm generating means to generate an alarm to prevent welding failure due to insufficient heating. I can announce.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a circuit diagram of the stud welder of the present invention. Further, in FIG. 2, A shows a current waveform, B shows a lifted (raised) state of the stud, C shows a temperature state of the welded portion, and D shows time. First, referring to FIG. 1, a stud welding machine 1 according to the present invention includes a welding gun 4 that holds a stud 3 so that a welded portion can come into contact with a base material 2, and a predetermined gap between the stud 3 and the base material 2. A power source 5 connected to the welding gun to supply electrical power. Then, the power source 5 and the welding gun 4 are connected to each other, and electric power for forming a pilot arc and a subsequent main arc between the stud 3 and the base material 2 is generated from the power source as shown by a current waveform of FIG. 2A. And a control device 6 for controlling the welding gun so that the stud is pressed against the base material at a predetermined time.

The control device 6 detects the voltage between the stud and the base metal and outputs a signal indicating that the stud is in pressure contact with the base metal, and the power supply 5 to the welding gun 4. A current detection device 8 for detecting the supplied welding current,
A power supply control device 9 for controlling the power supply 5 in response to these detection signals is provided. The power source 5 is a chopper type high frequency power source, and the power source 5 is PWM controlled. Therefore, the power supply 5 is controlled so that its current is suitable for generating the pilot arc and the subsequent main arc while always maintaining a constant voltage. That is, the current is controlled to be small during the pilot arc, and a large current is controlled to flow during the main arc.

Further, the control device 6 is provided with a time setting device 10 for setting the duration of the main arc (the time indicated by 11 in D of FIG. 2). In addition to the control, the lift device of the welding gun 4 is controlled so that the stud 3 held by the welding gun 4 starts to be lifted (raised) at the start of the set time and the lift is finished after a predetermined time has elapsed. .

In the stud welding machine 1 having the above structure,
A constant voltage and a current 13 of the magnitude shown in the waveform of FIG.
Electric power consisting of 14 and 15 is supplied from the power supply 5 to the welding gun 4. The electric current first generates a pilot arc, so that a small electric current 13 is supplied from the power source 5 between the stud 3 held by the welding gun 4 and the base material 2. As shown by the inclined portion 17 of the waveform B in FIG. 2, the stud 3 is gradually lifted from the base material 2 by a predetermined height lift device from the start of the pilot arc. As shown by the portion 18 of the waveform B in FIG. 2 showing the lifted state of the stud, a large current 14 for generating a main arc is supplied from the power source 5 after being pulled up to a predetermined height.

Due to the generation of the main arc, the tip portion of the stud and the welded portion of the base material are gradually heated, and as shown by the portion 21 of C in FIG. When heated for a time, the temperature is raised to an appropriate temperature in the range of the lower limit level 22 and the upper limit level 23. Then, the main arc current should be limited to a small value so that this temperature is within the proper range (in other words, the temperature does not exceed the upper limit level 23).

For this reason, the control device 6 includes the time setting device 1
Said duration defined by 0 (time 1 in D of FIG. 2)
After the lapse of 1), the power supply 5 is set so that the current supplied to the welding gun gradually decreases as shown by the waveform 15 in FIG.
Are in control. If the stud is pressed against the base material during this descent, both the welded part of the stud and the base material part are properly melted, so that the welding is performed well. Therefore, the control device 6 stops the drive of the lift device of the welding gun 4 and brings the stud 3 into pressure contact with the base material 2 while the current is decreasing (the portion of the waveform 15 in FIG. 2A). This allows the stud 3
Is properly welded to the base material 2 at that position.

In the present invention, when the stud 3 is pressed against the base material 2, the voltage between the two members becomes zero, so that the voltage detecting device 7 outputs the pressing signal as it is. Voltage detector 7
When the pressure contact signal from the power supply 5 is received, the voltage control device 9 of the control device 6 sends a control signal to the power supply 5 to stop the power supply from the power supply 5. That is, in the present invention, the current is cut off after confirming that the stud 3 is pressed against the base material 2, and thus the timing difference between the pressure contact and the power supply can be reliably prevented.

Further, in the present invention, as described above, the control device 6 is provided with the time setting device 10 for arbitrarily setting the duration 11 of the main arc.
However, after the lapse of the duration, the power supply is controlled so that the current supplied to the welding gun is gradually decreased. And
The time setting device 10 controls the welding gun so that the stud 3 is pressed against the base material 2 while the current is dropping. Therefore, it is possible to prevent excessive melting even when the timing of pressing the stud 3 is longer than a predetermined time.

Further, in the present invention, there is provided a device 25 for issuing an alarm when the time during which the stud 3 is pressed against the base material 2 exceeds a predetermined time length. In other words, when the melting temperature of the welded portion of the stud 3 and the base material 2 deviates from an appropriate range, welding is not properly performed even if pressure welding is performed. Therefore, the alarm device 25 issues the warning. The alarm device 25 does not give an alarm while the temperature of the welded portion (see the graph of C in FIG. 2) is within a certain range with reference to the time point 26 determined by the duration 11 shown in D of FIG. If the temperature of the welded portion is too low, or if the base material 2 is excessively melted and a hole is formed in the base material 2, an alarm is issued. This time range is shown with respect to the time point 26 in FIG. 2D, the front time 27 and the rear time 28, and when these time 27 and 28 are exceeded, the alarm device 25 activates the audible alarm. Or it issues a visual alarm. Therefore, when the time when the stud is pressed against the base metal does not reach the predetermined time, the alarm generation means is activated to generate an alarm, which can notify the welding defect due to insufficient heating and excessive melting. Welding failure due to

Further, the voltage control device 9 includes an alarm device 2
In addition to the supply of the operation signal to the power source 5, the power source 5 is supplied after a fixed time (28) after the duration (11) of the main arc.
Has a function of stopping the supply of electric power to the welding gun 4. This function can prevent accidents such as punching of the base material due to excessive melting.

[0019]

According to the present invention, means for outputting a signal indicating that the stud is pressed against the base metal is provided, and the power supply from the power supply to the welding gun is stopped after receiving the pressure contact signal. After the stud is pressed against the base material, the current is cut off, and the timing difference between the pressure contact and the current supply can be prevented. Further, the controller provided with means for setting the duration of the main arc controls the power supply so that the current supplied to the welding gun is gradually decreased after the duration has elapsed. Timing can also be controlled appropriately. In addition, when the time to press the stud against the base metal exceeds a predetermined time length, an alarm is provided so as to prevent defects such as punching of the base metal due to excessive melting, and the press-contact time to the predetermined time. Even if it does not reach the limit, an alarm is generated to notify of welding failure due to insufficient heating.

[Brief description of drawings]

FIG. 1 is a block diagram of a control device for a stud welder according to the present invention.

FIG. 2 is a waveform diagram of each part of the control device of FIG.

[Explanation of symbols]

 1 Stud Welder 2 Base Material 3 Stud 4 Welding Gun 5 Power Supply (PWM Chopper Type Power Supply) 6 Control Device 7 Voltage Detection Device 8 Current Detection Device 9 Power Supply Control Device 10 Time Setting Device 11 Duration 13 Pilot Arc Current 14 Main Arc Current for use 15 Current drop 18 Stud upper limit position 21 Stud melting temperature

Claims (4)

[Claims] 1. A welding gun for holding a stud so that a welding tip can contact the base material, a power source connected to the welding gun for supplying a predetermined electric power between the stud and the base material, and a power source. Connected to the welding gun and controlling the electric power that forms the pilot arc and the subsequent main arc between the stud and the base metal to be supplied from the power supply to the welding gun. A stud welding machine comprising a control device for controlling a welding gun so as to press-contact at a predetermined time, wherein the control device detects a voltage between the stud and the base metal, and the stud is pressure-contacted with the base metal. Stud welding, characterized in that detection means is provided for outputting a signal indicating that the control device stops the supply of electric power from the power supply to the welding gun after receiving the pressure welding signal from the detection means. . 2. The control device is provided with means for setting the duration of the main arc, and the control device is configured to gradually reduce the current supplied to the welding gun after the duration has elapsed. The stud welder according to claim 1, wherein the welding gun is controlled so that the welding gun presses the stud against the base metal so that the welding gun is controlled so that the current is decreasing. 3. The control device is provided with means for issuing an alarm when the time during which the stud is pressed against the base material exceeds a predetermined time length, and when the alarm is issued, the control device outputs the alarm. The stud welding according to claim 1 or 2, wherein, apart from the generation, the power supply is controlled so that the power supply from the power supply is stopped after a fixed time after the duration of the main arc has elapsed. Machine. 4. The control device activates the alarm generating means to generate an alarm when the time for pressing the stud against the base material does not reach a predetermined time. The stud welder according to any one of to 3.