JP2558109Y2 - 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 for performing a pushing operation of a stud reinforcing bar or a steel rod (hereinafter referred to as a "stud reinforcing bar") into a molten pool in two stages, high speed and low speed.

[0002]

2. Description of the Related Art In a two-stage push-in stud welding method disclosed in Japanese Patent Application Laid-Open No. 3-258462, a ferrule made of heat-resistant porcelain is first fitted to the front end of a stud reinforcing bar. It is brought into contact with the surface of the welding partner. In this state, the welding power is turned on,
An arc is generated from the tip projection of the stud reinforcing bar. Simultaneously with or immediately after the arc is generated, the stud reinforcing bar is moved backward by a predetermined distance (for example, 2 to 3 mm) from the welding partner. Then, the arc is maintained for a required time (for example, 0.7 to 0.9 seconds) set according to the diameter of the stud reinforcing bar, the ambient temperature, and the like, and the front end portion of the stud reinforcing bar and the surface portion of the welding partner are melted. .

[0005] Immediately before the arc is cut, the stud reinforcing bar is moved forward toward the welding partner. The forward movement speed is high (for example, 300 mm / sec) until the front end of the stud rebar reaches the pool surface of the molten metal, but is low after the front end of the stud rebar reaches the pool surface of the molten metal. (For example, 30 mm / sec). During this welding process, the ferrule prevents the molten pool from dripping and, at the same time, eliminates air by arc pressure to shield the molten metal from air. After welding is completed, the ferrule is broken and removed.

As described above, in the above-mentioned stud welding method, in a state where an arc is generated from the front end of the stud reinforcing bar, the stud reinforcing bar is moved forward at a high speed until it reaches the pool surface of the molten metal, and then the stud reinforcing bar is moved at a low speed. The forward movement allows the stud rebar to be advanced to a predetermined position without disturbing the pool before the molten metal hardens, thereby enabling high-quality stud welding with a uniform margin over the entire circumference. However, in order to perform this with good reproducibility, it is necessary that the stud reinforcing bar is properly and precisely moved at a predetermined timing and speed in relation to the generation and cutting of the arc.

In a conventional stud welding machine, an air cylinder is used as a driving means for moving the stud reinforcing bar forward and backward.
Speed control and position control are performed by adjusting the air pressure and the speed control valve. In such an air drive system, the response speed of the air cylinder changes depending on the length and thickness of the air hose. Therefore, it is difficult to stably perform high-quality stud welding with a two-stage press-in method requiring high control. In addition, the overall weight of the stud reinforcing bar has become heavy due to the recent demand for a large diameter, but such an increase in the weight changes the speed curve and further reduces the reproducibility.

[0006]

[Problems to be solved by the invention] Therefore, the purpose of the invention is to obtain a 2
An object of the present invention is to provide a stud welding machine in which stud welding of a step-in type always takes the same speed curve and can be reliably performed.

[0007]

The stud welding machine according to the present invention will be described with reference to the accompanying drawings.
An arc detector 3 for detecting the occurrence of an arc between the welding partner 1 and the stud reinforcing bar 2 is provided. The arc detector 3 receives the arc detection signal and moves the stud reinforcing bar 2 by a predetermined distance from the welding partner 1 at a predetermined speed. And outputs a first-stage pushing operation signal for causing the stud reinforcing bar 2 to advance at a predetermined speed to the pool surface of the molten metal immediately before the arc sustained for the required time is cut, and then a first-stage pushing. An arithmetic processing unit 4 for outputting a second-stage push-in operation signal for moving the stud reinforcing bar 2 to a required depth beyond the pool surface of the molten metal at a speed slower than the time is connected.

[0008] Each operation signal from the arithmetic processing unit 4 is input to an encoder 6 of a servo motor 7 mounted on the machine frame 5, and a screw rod 10 is connected to an output shaft 8 of the servo motor 7. Reference numeral 10 is rotatably supported by a bearing 9 provided on the machine frame 5. Screw rod 10 blocked from moving in the axial direction
A nut body 14 is screwed into the nut body 14, and a base 13 of a clamp 12 that advances and retreats with respect to the welding counterpart 1 along the rail 11 provided on the machine frame 5 is fixed to the nut body 14.

[0009]

After fitting the ferrule 15 to the front end of the stud reinforcing bar 2 and loading the ferrule 15 into the ferrule holder 16 and loading the stud reinforcing bar 2 into the clamp 12, the tip projection of the stud reinforcing bar 2 and the ferrule 15 are removed. It is brought into contact with the surface of the welding partner 1. The contact between the stud reinforcing bar 2 and the welding partner 1 is detected by a known touch sensor,
The welding power source 17 is turned on. Tip protrusion 2 of stud reinforcing bar 2
The voltage / current value of the arc generated from a is measured, and an arc detection signal output from the arc detector 3 is input to the arithmetic processing device 4 when the measured value reaches a predetermined level.

The arithmetic processing unit 4 sends a retreat operation signal of the stud reinforcing bar 2 to the servomotor 7, so that the servomotor 7 rotates in a specific direction. The rotational movement of the output shaft 8 of the servomotor 7 is performed by a movement conversion mechanism composed of a screw rod 10 whose axial movement is restricted and a nut body 14 whose rotation is restricted. Is converted into a linear motion of the base 13. Therefore, the clamp 12
The stud reinforcing bar 2 held backward is moved backward by a predetermined distance from the welding partner 1 at a predetermined speed.

The arc is maintained for a time set by a well-known timer means even after the stud reinforcing bar 2 is moved backward. The arithmetic processing unit 4 sends a first-stage push-in operation signal to the servomotor 7 immediately before the arc is cut off. Therefore, the servo motor 7 rotates in the opposite direction, and the base 13 of the clamp 12 moves forward toward the welding partner 1. The moving amount and moving speed of the servomotor are detected by the encoder 6 and controlled by the arithmetic processing unit. As a result, the front end of the stud reinforcing bar 2 advances at a predetermined speed to the molten metal pool surface in the ferrule 15. Next, the arithmetic processing unit 4 sends a second-stage push-in operation signal to the servomotor 7.

Therefore, the servo motor 7 rotates at a reduced speed in the same direction, and the front end of the stud reinforcing bar 2 moves forward at a low speed to a required depth in the molten metal beyond the pool surface. After the entire stud welding process is completed in this manner, the clamp 1
2 releases the stud reinforcement. The ferrule 15 is broken down and removed, revealing a weld which is overfilled to the required height and width.

[0013]

As described above, in the stud welding machine of the present invention, the nut body 14 is fixed to the base 13 of the clamp 12 which advances and retreats with respect to the welding counterpart 1 along the rail 11 to prevent movement in the axial direction. The nut body 14 is screwed onto the screw rod 10 supported by the bearing body 9 to connect the arc detector 3 to output a retreating signal, a first-stage pushing operation signal, and a first-stage pushing operation signal. Since the device 4 is connected to the encoder 6 of the servo motor 7 and the output shaft 8 of the servo motor 7 is connected to the screw rod 10, the drive circuit system for moving the stud rebar 2 forward and backward is all electrically configured and operated. Because of its excellent responsiveness, the forward and backward movement of the stud rebar 2 is performed properly and precisely at a predetermined timing and speed related to arc generation and cutting, and is affected by differences in weight, welding posture, and the like. To reliably perform stud welding two stages push scheme always take the same speed curve.

[0014]

In the illustrated embodiment, the diameter of the stud reinforcing bar 2 is 22 mm and the welding current is set to 1850A. The distance of the backward movement of the stud reinforcing bar 2 is 2 mm, and the speed of the backward movement is 100 mm / sec. The duration of the arc is 0.8 sec, the distance of the first stage pushing operation of the stud reinforcing bar 2 is 3.0 mm, and the forward speed is 200 mm / sec.
It is. The distance of the second-stage pushing operation of the stud reinforcing bar 2 is 3.5 mm, and the forward speed is 30 mm / sec.

The output shaft 8 of the servomotor 7 and the screw rod 10 are connected by a coupler 18. A ferrule holder 16 is provided at the tip of an arm 19 projecting from the front of the machine frame 5. An electromagnet unit 20 for adsorbing and fixing to the contact partner 1 is provided.

[Brief description of the drawings]

FIG. 1 is a schematic right side view of a stud welding machine according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between movement of a stud reinforcing bar and a welding arc in the stud welding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Welding partner 2 Stud reinforcing bar 3 Arc detector 4 Arithmetic processing unit 5 Machine frame 6 Encoder 7 Servo motor 8 Output shaft of servo motor 9 Bearing body 10 Screw rod 11 Rail 12 Clamp 13 Base of clamp 14 Nut body 15 Ferrule 16 Ferrule holder 17 Welding power source 18 Coupler 19 Arm 20 Electromagnet unit

Claims (1)

(57) [Scope of request for utility model registration] An arc detector for detecting the occurrence of an arc between a welding partner and a stud reinforcing bar; receiving an arc detection signal and outputting a retreat operation signal for retracting the stud reinforcing bar by a predetermined distance from the welding partner at a predetermined speed. Then, immediately before the arc sustained for the required time is cut, a first-stage pushing operation signal for causing the stud reinforcing bar to advance at a predetermined speed to the pool surface of the molten metal is output, and then the stud reinforcing bar is driven at a slower speed than at the time of the first stage pushing. An arithmetic processing unit for outputting a second-stage push-in operation signal for advancing to a required depth beyond the pool surface of the molten metal; a servomotor with an encoder fixed to the machine frame and receiving each operation signal from the arithmetic processing unit; A screw rod connected to the output shaft of the servomotor, rotatably supported by a bearing body provided on the machine frame, and prevented from moving in the axial direction; and provided on the machine frame. A stud welding machine comprising a nut body fixed to a base of a clamp that advances and retreats with respect to a welding partner along a rail, and is screwed to the screw bar.