JPS5913302B2 - Arc welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a manual or semi-automatic arc welding method in which heat input to a workpiece is increased or decreased in accordance with the moving speed of a manual welding holder or welding torch.

Conventionally, in manual or semi-automatic arc welding equipment, the welding holder 10 is operated while generating an arc between the tip of the welding rod held in the welding holder or the tip of the consumable electrode fed from the welding torch and the workpiece. Alternatively, the welding torch is moved manually, but in order to keep this moving speed at a constant value and increase or decrease the moving speed in response to fluctuations in the welding current or power supply voltage, it requires a high degree of skill on the part of the welding operator. and require excessive concentration of nerves.

Therefore, it is difficult for a worker with a low level of skill or a worker who does not have sufficient concentration of nerve to maintain the moving speed of the welding holder or welding torch at a constant value without any discrimination criteria. Furthermore, even if a skilled worker concentrates, it is difficult to adjust the moving speed of the welding holder according to fluctuations in the welding current or power supply voltage20, and there is a drawback that a constant welding result cannot always be obtained. . Therefore, a welding speed indicating device has been proposed in which a movable body that provides a desired moving speed is attached with an indicator needle or a light source that the welding operator can identify during welding. During welding, the welding speed indicator mentioned above was often overlooked because the welding point was carefully observed.

Moreover, when this indicating device is brought close to the line to be welded, it will be overheated by arc heat, and conversely, if it is moved away from it, the error 30 will increase depending on the position where the operator looks. In view of the above, the present invention proposes a manual or semi-automatic arc welding method that keeps the heat input per unit length of the workpiece substantially constant regardless of fluctuations in the moving speed of the welding holder or welding torch. That's 35.

The present invention &A A manual or semi-automatic arc welding method for welding a workpiece while moving an arc along a welding line, in which first and second detection detect arc light or high temperature of the arc or molten part. The first detector is moved in advance by an electric motor whose speed is determined by a motor control circuit, and the device is moved approximately along the welding line at a preset speed or at a speed approximately proportional to the power supply voltage, welding current, or welding voltage. move it.

When the moving speed of the arc becomes greater than the moving speed of the first and second detectors and the preceding first detector detects arc light or high concentration, the first detector detects arc light or high concentration.
increasing the heat input to the workpiece by increasing the output current, output voltage, or electrode feeding speed of the welding machine by a welding machine output control means that receives the output signal generated by the detector; Further, when the moving speed of the arc becomes smaller than the moving speed and the following second detector detects arc light or high temperature, the second detector receives an output signal generated by the second detector as input. By reducing the output current, output voltage, or electrode feeding speed of the welding machine by the welding machine output control means, the heat input to the workpiece is reduced. Hereinafter, the arc welding method of the present invention will be explained in detail with reference to the drawings. FIG. 1A shows an example of an apparatus used when carrying out the arc welding method of the present invention by aligning the objects to be welded 1 and 1 horizontally and manually moving the welding holder 3 connected to the welding machine 2. As shown, one output terminal 2a of the welding machine 2 is connected to the workpieces 1, 1 directly or through a welding current detector 9, and the other output terminal 2b is connected to the welding holder 3.
It is connected to the.

A threaded rod 4a is arranged along the weld line 1a of the object 1 to be welded. One end of this threaded rod is connected to the output shaft of the electric motor 4b, and the other end is supported by a bearing 4c. Electric motor 4b
By attaching a magnet to the bearing 4c, these can be easily fixed to the object to be melted. The screw rod 4a has the first
The female screws provided on the movable base 4d supporting the second detectors 51 and 52 are screwed together, and the screw rod 4a is screwed together by the electric motor 4b.
By rotating the detector, the first and second detectors 51 and 52 are moved along the welding line. The screw rod 4a, the electric motor 4b, the bearing 4c, and the movable base 4d constitute a driving device 4 for the first and second detectors.
The first and second detectors 51 and 52 are detectors that detect the arc light or the high temperature of the arc or the molten part, and these detectors are arranged so that the first detector 51 precedes the welding direction. They are arranged at regular intervals in the direction of the weld line. The outputs of the first and second detectors 51 and 52 are supplied to first and second welding machine output control circuits 61 and 62 of the welding machine output control means 6, respectively. The first welding machine output control circuit 61 increases the output of the welding machine by a set value when the first detector detects arc light or high temperature of the molten part to increase heat input to the workpiece. . In addition, the second welding machine output control circuit 62 reduces the output of the welding machine by a set value when the second detector 52 detects arc light or high temperature of the molten part to prevent heat input to the workpiece. reduce
Here, "output of the welding machine" refers to the output current of the welding machine,
Refers to the output voltage or electrode feeding speed. The electric motor 4b is controlled by a motor control circuit 8.

The motor control circuit 8 supplies voltage to the motor by detecting at least one of welding current, arc voltage, or a signal generated by generation of arc light or closing of a welding start pushbutton switch, and supplies voltage to the motor. It is configured to detect at least one of voltage, extinction of arc light, or a signal from a welding end push button switch to cut off the voltage supplied to the motor. The moving speed of the detectors 51 and 52 is increased or decreased according to the increase or decrease in heat input to the workpiece by the welding machine output control circuits 61 and 62, but this moving speed depends on the groove cross-sectional area, welding current value, etc. The control circuit 8 is set in advance so that the appropriate speed is determined accordingly. If there is little variation in the input voltage to the welding machine and motor control circuit, or if a power supply voltage fluctuation compensation device is attached and the welding current value and motor supply voltage value are approximately constant, no increase or decrease in heat input will occur. As far as possible, it is sufficient to move the detector at a predetermined constant value. However, if the power supply voltage fluctuates significantly or the welding current value fluctuates, the amount of deposited metal can be increased by increasing the power supply voltage, welding voltage, or welding current separately from speed control according to increases or decreases in heat input. In order to increase the moving speed of the detector in accordance with the power supply voltage, welding current, or welding voltage, the motor control circuit 8 is configured to move the detector at a speed substantially proportional to the power supply voltage, welding current, or welding voltage. The welding current detector 9 is a shunt, a current transformer, a DC current transformer, etc. that outputs signals for controlling the movement start, movement speed, movement stop, etc. of the detectors 51 and 52. and the workpiece 1 to be welded, and supplies a signal to the motor control circuit 8 while welding current is being applied. In addition, 10 is a welding machine 2, control circuits 8, 61 and 6.
This is an AC power source that provides power to 2. During welding, while moving the detectors 51 and 52 at an appropriate moving speed,
The operator manually moves the welding holder 3 to the welding line 1 while the arc is occurring.
Move it along a.

If the moving speed of the welding holder is predetermined based on the groove cross-sectional area, welding current value, etc., the welding holder is always positioned between the first and second detectors as shown in FIG. 1A. Therefore, both detectors 51 and 52 do not detect arc light or high temperature and do not output a signal, and the output of welding machine 2 maintains a preset value. However, if the moving speed of the welding holder is too fast and the corresponding positions of the arc light and the detectors 51 and 52 are shifted, and the detector 51 detects the arc light or high temperature as shown in FIG. 1B, the welding machine outputs The control circuit 61 outputs a signal to increase the output of the welding machine 2 by a set value to increase the heat input to the workpiece. For example, if a drooping special power source is used for manual welding, the output current of the welding machine can be increased; if a constant voltage power source is used for semi-automatic welding, the electrode feeding speed of the welding machine can be increased. The output voltage of the welding machine may be increased, or both may be increased. In this way, when the output of the welding machine, such as the output current, increases, the output of the motor control circuit 8 is also increased by the output of the welding current detector 9, and the output of the welding current detector 9 is increased.
Increases the movement speed of 2 by the set value. Further welding continues, and the moving speed of the welding holder 3 is detected by the detectors 51 and 52.
If the moving speed becomes slower than the moving speed of the detectors 51 and 52,
Both stop the output signals, and the output of the welding machine also returns to its original value. If welding continues from this state and the moving speed of the welding holder becomes still slower, the detector 52 detects arc light or high temperature as shown in FIG. 1C, and the welding machine output control circuit 62 outputs a signal. The output of the welding machine 2 is reduced by a set value to reduce the heat input to the workpiece. When the output of the welding machine decreases in this way, the welding current detector 9
The output of the motor control circuit 8 is also reduced by the output of , and the moving speed of the detectors 51 and 52 is reduced by a set value. In this way, the output of the welding machine is increased or decreased depending on the moving speed of the welding holder 3 to increase or decrease the heat input to the workpiece 1, and furthermore, the detection By increasing or decreasing the moving speed of the vessels 51 and 52, the fluctuation range of heat input per unit length of the workpiece can be reduced.
FIG. 2 shows a case where the arc welding method of the present invention is carried out by aligning the objects to be welded 1 and 1 vertically and manually moving the welding holder connected to the welding machine 2. In this case, the drive device 4 is constituted by a cart 4e that has a built-in electric motor 4b and moves the first and second detectors, and a flexible guide rail 4f. In this case as well, if magnets are attached to the wheels of the guide rail 4f and the trolley 4e,
These can be easily fixed to the object to be welded. Other configurations and operations are the same as those in FIG. 1. Note that the welding machine output control circuits 61 and 62 of the welding machine output control means 6 in FIGS. 1 and 2 have a time-limiting element for delay operation, and the arc may be temporarily interrupted by camera shake or rocking motion. Control circuits 61 and 62 do not operate when light is detected by the detector or when light is no longer detected.

According to the arc welding method of the present invention, unlike previously proposed welding methods, there is no need for the welder to pay attention to the movable body that moves at a set speed during welding, so Since the molten part can be observed closely and the variation range of heat input per unit length to the workpiece is automatically suppressed, uniform welding results can be obtained. Furthermore, in the arc welding method of the present invention, when the manual movement speed of the welding holder deviates from the planned value, unlike the method of simply indicating with an indicator light, buzzer, etc., the work place is outdoors in a very bright place. Even in a noisy place, there is no misidentification, and worker fatigue can be reduced, which is of great practical benefit.

[Brief explanation of drawings]

FIG. 1A is a schematic configuration diagram of an apparatus used in the first embodiment of the present invention in which welding is performed by horizontally abutting objects to be welded; FIGS. 1B and 1C are explanatory diagrams explaining the detection operation of the detector; FIG. 2 is a schematic diagram of an apparatus used in an embodiment in which objects to be welded are welded vertically butted against each other. 1... object to be welded, 1a... welding line, 3
...Welding holder or torch, 4...
・1 Drive device, 4a...screw rod, 4b...
...Electric motor, 4c...Bearing, 4d...
Movable platform, 4e... Cart, 4f... Guide rail, 51, 52... Photo detector or temperature detector, 61, 62... Welding machine Output control circuit.

Claims (1)

[Claims] 1. In manual or semi-automatic arc welding methods that weld while moving the arc along the welding line of the workpiece,
The first and second detectors for detecting the arc light or the high temperature of the arc or molten part are driven by a motor whose speed is determined by a motor control circuit, with the first detector being preceded by a preset speed or power source. The first detector is moved approximately along the welding line at a speed approximately proportional to the voltage, the welding current, or the welding voltage, and the arc moves ahead of the first and second detectors so that the moving speed of the arc becomes greater than the moving speed of the first and second detectors. When the detector detects arc light or high temperature, the output current, output voltage, or electrode feeding speed of the welding machine is controlled by a welding machine output control means that receives the output signal generated by the first detector as an input. By increasing the heat input to the workpiece, and when the moving speed of the arc becomes smaller than the moving speed and the following second detector detects arc light or high temperature. By reducing the output current, output voltage, or electrode feeding speed of the welding machine by the welding machine output control means which receives the output signal generated by the second detector as input, the input to the workpiece is reduced. Arc welding method to reduce heat.