JP2984392B2 - Stud welding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stud welding machine, and more particularly to a stud welding machine, in which a stud is optimally lifted from a base material to generate an arc discharge, and thereafter, the stud is pressed against the base material in an optimal manner, so that a constantly stable welding is performed. A workable stud welding machine.

[0002]

2. Description of the Related Art A welding gun having a collet for holding a stud so that a welding surface can be brought into contact with a base material, and a power supply connected to the welding gun so as to supply a predetermined electric power between the stud and the base material. A control device that controls a power supply so as to form a pilot arc and a subsequent main arc between the stud and the base material, and controls a welding gun so as to press the stud against the base material at a predetermined time. Stud welders consisting of are well known. This stud welding machine is often used to weld studs to the car body, etc.
A clip or the like is attached to the welded stud, and a heat insulating material or the like is attached to the vehicle body or the like by the clip.

In a conventional stud welding machine, a spring for pressing a collet downward to press a stud against a base material is provided on a welding gun. A solenoid (that is, an electromagnet) having a force that overcomes the force of the spring is provided on the welding gun, and the solenoid is biased to lift the stud by a predetermined height so as to generate a pilot arc and a main arc. After the stud and base material are melted by the main arc, when the solenoid is deenergized,
The stud is pressed against the base material by the force of the spring, so that the molten stud and the base material portion are welded to each other.

[0004]

In such a conventional stud welding machine, the spring force is constant, and the lift force and stroke length of the solenoid are also constant. However, there is a disadvantage that the height of the lift and the timing of the pressure contact change. Further, when the welding gun is perpendicular to the base material and when the welding gun is inclined, the welding strength and the timing of the welding change, and the change cannot be accommodated. Furthermore, it was not possible to cope with the secular change of the spring force and the change of the resistance of the sliding portion due to the vertical movement of the collet. For this reason, due to these changes, sufficient arc discharge has not been performed, or the timing and pressure contact force have not been adjusted, resulting in poor welding.

Accordingly, an object of the present invention is to control the timing of lift of the stud of the welding gun, the height of the stud, the timing of the pressure welding, and the strength thereof in accordance with the base material, the stud, the posture of the welding gun, and the like. An object of the present invention is to provide a stud welding machine in which appropriate control is maintained even by using a stud.

[0006]

According to the present invention, there is provided, in accordance with the present invention, a welding gun having a collet for holding a stud so that a welding surface can be brought into contact with a base material; A power source connected to the welding gun so as to supply a predetermined power therebetween, and a power source is controlled so as to form a pilot arc and a subsequent main arc between the stud and the base material, and the stud is connected to the base material. And a control device for controlling the welding gun so as to press the stud against the base material at a predetermined time, wherein the welding gun is provided with a collet so as to lift the stud or press the stud against the base material. A motor for moving up and down, first sensor means for detecting a lift height and a lift time of the stud moved by the motor, and a stud held by a collet. Second sensor means for detecting the strength of pressing against the material is provided, and the control device receives signals from the first sensor means and the second sensor means and drives the motor so as to drive the motor. The timing of the lift of the stud forming the pilot arc and the subsequent main arc and the lift height are determined by a motor that has received a drive signal from a control device whose preset value has been selected in advance, The timing of the pressing and the pressing strength to the base material at the time of pressing are also determined by a motor which receives a drive signal from a control device in which another set value is previously selected, and the pressing strength of the stud is determined by the second sensor means. A stud welding machine is provided wherein the motor is biased to a predetermined strength upon detection.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of a stud welding machine of the present invention. The figures of (A), (B), (C) and (D) in FIG.
(A) shows the current waveform to the welding gun, (B) shows the pattern of the lift height of the stud, (C) shows the moving speed of the stud up and down, and (D) shows the time when the stud goes up and down. It shows acceleration.

First, in FIG. 1, a stud welding machine 1 according to the present invention comprises a welding gun 2 and an operation circuit 3 for operating the welding gun. At the tip of the housing 4 of the welding gun 2, a cylindrical shield 5 for inert gas or the like is provided, and a collet 6 for holding a stud is provided inside the shield. In the figure, a stud 7 is held by a collet 6. The tip of the shield 5 is applied to a predetermined location of the base material 8. A tube 9 for feeding the stud 7 is provided above the collet 6 so that the stud 7 can be automatically supplied to the collet 6. Further, a cable tube 10 for supplying electric power to the welding gun 2 and controlling the operation of the welding gun 2 is provided at an upper portion of the housing.

In the present invention, the housing 4 is provided with a motor 12 as a driving means for moving the collet 6 up and down so as to lift the stud 7 and press the stud against the base material 8. . When this motor 12 is energized, it is sufficient that the collet 6 can be moved up and down.
Electric motors such as linear motors (preferable because of a small number of parts and easy control) and rotary motors (requiring gear means for converting a rotary motion into a linear motion so that a collet can be moved up and down) are used. It is typical,
It goes without saying that any other motor such as an air motor or an ultrasonic motor can be used. Further, from the viewpoint of control, a servomotor is preferred. In the present invention, a sensor box 13 for housing two sensors is provided inside the housing 4. The first sensor emits a signal indicating the height of the collet 6 at the time moved by the motor. This first sensor emits a signal indicating the height and time of the upper and lower sides of the collet, and thus serves as a sensor for detecting the height and time of the lift of the stud 7. The first sensor can be composed of, for example, a mechanical encoder, an optical encoder, or the like, and a converter that converts a detection output of the encoder into an electric signal. The sensor box 13 is provided with a second sensor for detecting the strength of the stud held by the collet against the base material.

The operating circuit 3 includes a power supply 16 connected to the welding gun via a line 15 so as to supply a predetermined power between the stud 7 held by the collet 6 of the welding gun 2 and the base material 8. It has. Further, a control device 17 is provided in the operation circuit section 3, and the power supply 16 is controlled by the control device 17 so as to form a pilot arc and a subsequent main arc between the stud and the base material.

In the present invention, the control device 17 not only controls the power source 16 but also controls the welding gun 2 via the line 18.
Of the motor 12 is controlled. When the motor 12 is actuated, the stud 7 can move up and down, and by this movement the first sensor of the sensor box 13 emits a signal indicating the height and time of the collet up and down, and this signal is sent via line 19 to the control unit 17. In response to the feedback signal, the control device 17 controls the energization of the motor in accordance with a preset value, forms a pilot arc and a main arc between the stud and the base material, and then sets the stud to the base material. The stud welding is optimally performed while maintaining the optimum pressing strength by receiving the pressing strength signal from the second sensor. This control device can be easily realized by using a microcomputer or the like. Although not shown, the control device 17 is provided with a button switch or the like that can arbitrarily set the time of the pilot arc and the time of the main arc, and a display that displays a set value.

Hereinafter, the operation of the control device according to the present invention will be described with reference to FIG. First, the control device 17
Supplies a small current for the pilot arc from the power supply 16 to the welding gun 2 (see the waveform (A) in FIG. 2). At substantially the same time, the stud 7 in contact with the base material 8 is lifted by driving the motor 12 (see the pattern in FIG. 2B). When the stud 7 is lifted from the base material 8 by a certain height, a large current is supplied from the power source 16, a main arc is generated between the stud and the base material, and the welding surface of the stud and the base material are heated. It is gradually melted. When the stud welding surface and base metal are properly melted,
The motor 12 is gradually reversed or deenergized, and the stud 7 is pressed against the base material 8. At the time of this pressing, the stud 7 is welded to the base material 8 by maintaining the pressing strength at a predetermined strength by the second sensor. The lift pattern shown in FIG. 2B generally has a trapezoidal shape as shown in the figure, but may have a triangular shape. At the moment of pressing, the stud welding surface softly lands on the base material surface. Such a pattern may be used (preferably, such a soft landing is performed because there is no scattering of a molten portion and welding is performed appropriately).

In the present invention, it is the motor 12 that raises and lowers the stud, so that the height of the lift, the time of the lift, and the speed and speed of the lift as shown in FIGS. The acceleration can be set arbitrarily,
The time of the pilot arc, the time of the main arc, the timing of the pressure welding, and the mode of the pressure welding at the time of the pressure welding can be arbitrarily set. For example, the height of the lift and the time of the lift can be confirmed by the signal from the first sensor. The speed can be calculated by differentiating the lift height signal from the first sensor by the lift time. It is obtained by differentiation, and such calculation is performed by a control device (microcomputer). Also, after the welding surface of the stud and the base material are melted by arc discharge, when the stud is pressed against the base material, the stud softly lands on the base material (ideally, the stud comes into contact with the base material at zero speed). Speed (acceleration) can be easily controlled. Further, the strength of the press contact after the stud has been brought into contact with the base material can be detected by receiving a signal from the second sensor, and the motor 12 is energized to maintain the press contact strength at an appropriate value.

[0014]

Therefore, according to the present invention, the stud can be moved up and down only by the motor without the need for a spring, the construction of the welding gun is simplified, and the height and timing of the lift are always set to appropriate values. And eliminates the need for springs and solenoids.This prevents welding failure due to variations in mechanical properties and aging of the springs, and eliminates the problem of scattered molten parts during pressure welding. The servo control is performed by the sensor and the sensor, so that the welding conditions can be controlled very accurately, and the stud lift and pressure welding can be performed with appropriate strength, so that welding defects can be minimized. The time, speed and acceleration of stud lift and crimping can be properly adjusted, preventing welding defects in this regard as well, and adjusting the crimping strength and lift pattern when crimping. Therefore it is possible to arbitrarily not only prevents spatter scatter, allowing the welding of the clean and powerful finish.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a stud welding machine according to the present invention.

FIG. 2 is a diagram showing a current waveform, a lift pattern, a speed pattern, and an acceleration pattern during operation of the stud welding machine of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stud welding machine 2 Welding gun 3 Operating circuit part 4 Housing 5 Shield 6 Collet 7 Stud 8 Base material 9 Stud feeding tube 12 Motor 13 Sensor box 16 Power supply 17 Control device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23K 9/20 B23K 9/073

Claims (1)

(57) [Claims] 1. A welding gun having a collet for holding a stud so that a welding surface can be brought into contact with a base material, and a power supply connected to the welding gun so as to supply a predetermined power between the stud and the base material. A control device that controls a power supply so as to form a pilot arc and a subsequent main arc between the stud and the base material, and controls a welding gun so as to press the stud against the base material at a predetermined time. In the stud welding machine, the collet is moved up and down on the welding gun so as to lift the stud and press the stud against the base material.
A motor ; first sensor means for detecting a lift height and a lift time of the stud moved by the motor ; and a stud held by a collet pressed against a base material.
Second sensor means for detecting the strength is provided, and the control device is configured to detect the intensity from the first sensor means and the second sensor means.
And drive the motor
Connected to the welding gun, the pilot arc and then
The main arc and the stud lift time forming
The lifting height and its lift height are controlled in advance by setting
Determined by the motor that receives the drive signal from the
The timing of the welding and the strength of the welding to the base material during the welding
Also, the drive signal from the control device for which another set value is selected in advance
Is determined by the motor that has received the
Is a predetermined strength detected by the second sensor means.
A stud welding machine characterized in that the motor is biased to the stud.