JPS6134903B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for detecting welding speed when manually moving a welding holder or a welding torch.

Normally, the amount of welding heat input to the weld zone is an important factor that affects the welding result. Generally, the arc voltage is E ₁
(volt), welding current I ₁ (A), welding speed V ₁ (cm/se
c) If the electrical input to the workpiece is P [KW], the heat input per unit length is Q [Kilo-Joule], and the constant is K ₁ , then Q = K ₁ P ₁ /V ₁ = K ₁ E ₁ I ₁ /V ₁ ...(1) holds true. This equation (1) can be expressed even more simply in some cases. For example, when manual welding is performed using a welding power source with constant current characteristics, the welding current I ₁ (A) has a substantially constant value, so if the constant is K ₂ , then Q = K ₂ E ₁ /V ₁ ...(2) holds true. In addition, when performing semi-automatic welding using a welding power source with constant voltage characteristics, the arc voltage E ₁
(volt) is a substantially constant value, so if the constant is K ₃ , then Q=K ₃ I ₁ /V ₁ (3) holds true.

Conventionally, in the automatic arc welding method, it is possible to easily obtain the signal V corresponding to the welding speed by detecting the traveling speed of the automatic traveling trolley, so heat input measurement in automatic welding machines and control based on the measured value have already been carried out. Proposed. However, in manual welding and semi-automatic welding methods, there is no automatic traveling trolley,
The welding speed V ₁ cannot be detected because the welding torch is artificially moved along the welding line. Therefore, conventionally, in manual welding or semi-automatic welding methods, it has not been possible to put into practical use a method or a device for simply, quickly and accurately detecting the welding speed, measuring welding heat input, and managing heat input such as controlling the output of a welding machine. I was late.

In the manual welding or semi-automatic welding method, the present invention provides an arc photodetector that can move approximately along the welding line, and uses a signal of the difference between the output signal of the detector and a preset reference signal to The present invention proposes to control the moving speed of the arc photodetector so that the detector follows the movement of the arc, and to obtain a signal V corresponding to the moving speed of the detector, that is, the welding speed. Once such a signal V is obtained, P/V can be measured from this signal V and a signal P corresponding to the power supplied to the workpiece and the welding electrode to measure the welding heat input, or to measure the welding heat input. By controlling the welding heat input by controlling current, arc voltage, etc., heat input management can be performed easily and quickly even in manual or semi-automatic welding.

Embodiments of the welding speed detection method and detection device of the present invention will be described in detail below with reference to FIG.

In Fig. 1, 1 is a workpiece having a welding line 1a, 2 is a welding electrode, and 3 is a welding electrode 2 and a workpiece 1.
This is an arc photodetector that receives arc light a generated between the two and outputs a signal corresponding to the position relative to the arc light. In the illustrated example, the arc photodetector 3 consists of a lens 4 and an optical potentiometer 5. The optical potentiometer 5 has a photoconductive cell 5c arranged between a metal film resistor 5a and an electrode 5b, and the lens 4 has a metal film resistor 5a.
An arc image b is formed on top of the arc image b. Metal film resistor 5
When an arc image is formed on a, the photoconductive cell 5c becomes conductive at the position where this image is formed, and the electrode 5b is connected to the metal film resistor 5a at this position. Since a constant voltage S is applied to both ends of the resistor 5a, the output terminals t _{1 and} t 1 of the optical potentiometer 5
During _t2 , a signal voltage F corresponding to the position of the arc image b, that is, the relative position between the detector 3 and the arc light a is obtained. For example, when the arc image b is at the illustrated position L ₀ (approximately the center position), the output voltage F of the optical potentiometer is approximately 1/2S. When the arc image b is at the position L ₁ shown in the figure, the output voltage F of the optical potentiometer is the minimum (approximately zero), and conversely, when the arc image b is at the position L ₂ shown, the output voltage F becomes the maximum (abbreviated S). Optical potentiometer 5
The output voltage F is output from the amplifier 6 along with the reference signal voltage R.
is input. The amplifier 6 amplifies a signal corresponding to the difference voltage between the output voltage F of the optical potentiometer and the reference voltage R, and outputs a signal voltage G. This signal G
is supplied to a drive source such as an electric motor 7. The reference signal voltage R is used to set the reference position _L0 of the arc image, and this position _L0 is usually set approximately at the center of the potentiometer 5, but it does not necessarily have to be set at the center. There isn't.

The arc photodetector 3, amplifier 6 and electric motor 7 are mounted on the same tracking truck 8 with wheels 8a and 8b. The output shaft of the electric motor 7 is a reduction gear 9, 1
The electric motor is connected to the driving side wheels 8a of the truck through the electric motor 0, and the truck 8 is driven by this electric motor. The trolley 8 is guided by appropriate guide means such as rails so as to travel in a direction substantially parallel to the welding direction. A speed detector 11 is also attached to the output shaft of the electric motor 7, and a signal V corresponding to the running speed of the tracking cart 8 can be obtained by this sensor.

In Fig. 1, 12 is a welding power source, and 13 is a welding power source.
is the signal E corresponding to the arc voltage and the current transformer 13a.
This is a power detection circuit which inputs a signal I corresponding to a welding current detected by the above method and outputs a signal P corresponding to instantaneous power E×I.

In the above device, the reference signal voltage R is set to zero before the arc a is generated, and the reference signal voltage R is applied at the same time as the arc a is generated. Now, suppose that when the arc a first occurs, the arc image b is exactly connected to the illustrated L ₀ set by the reference signal R. In this case, the difference between the output voltage F of the potentiometer and the reference voltage R is Since it is zero, amplifier 6 produces no output and therefore motor 7 remains stopped. Next, when the arc a is moved in the Z direction, the arc image b moves from the L ₀ position to the L ₁ position, so a difference occurs between the reference signal voltage R and the output voltage F of the potentiometer. , amplifier 6
An output is generated from the motor 7 and the electric motor 7 is started. As a result, the tracking cart 8 also moves in the X direction. In this case, the arc image b is a signal corresponding to the moving speed of the arc,
That is, it attempts to settle at a position corresponding to the difference between the reference signal R and the output signal F of the optical potentiometer 5, and the carriage 8 follows the arc a. Note that if the gain of the amplifier 6 is sufficiently large, the arc image b returns to the position L ₀ set by the reference signal R. When the moving speed of the arc a becomes slower than the moving speed of the cart 8, the arc image b will be connected to the _L2 side rather than the _L0 shown in the figure, so the resistor 5a and the electrode 5b will be connected at a position close to _L2 . and the output voltage F of the optical potentiometer 5
becomes larger than the reference signal voltage R. At this time,
When the amplifier 6 is configured to amplify only positive input signals, the output G of this amplifier becomes zero, and when the amplifier 6 is configured to amplify positive and negative input signals, the output G changes from positive to negative. Invert. Output G of amplifier 6
When becomes zero or negative, the electric motor 7 is decelerated and the speed of the truck 8 is reduced. Therefore, the arc image b tends to settle at a position corresponding to the moving speed of the arc and the difference between the signal, that is, the reference signal voltage R and the output signal F of the optical potentiometer, and the cart 8 follows the arc a. . If the gain of the amplifier 6 is sufficiently large, the arc image b returns to the position _L0 . In this way, in the above device, the arc photodetector 3 follows the movement of the arc a and moves at the same speed as the arc. The signal V obtained from the speed detector 11 therefore corresponds to the moving speed of the arc a. The signal V obtained in this way is, for example, the power detection circuit 1
It is used for the purpose of calculating the welding heat input together with the signal P corresponding to the electric power detected by No. 3.

As the speed detector 11, any arbitrary device such as a speed generator that generates a voltage proportional to the speed or a detector that generates a pulse corresponding to the speed can be used.

The arc light detector 3 may be of any type as long as it outputs a signal corresponding to the relative position with respect to the arc light, and is not limited to the example shown in FIG. 1. For example, in Figure 1, the light-receiving area of the photoconductor is uniform along the moving direction of the arc, but the light-receiving area of the photoconductor is shaped to gradually decrease or increase along the arc moving direction to correspond to the position of the arc light. It is also possible to use one adapted to obtain a signal. Figure 2 shows such an arc photodetector 3.
In the figure, 14 is a photoelectric conversion element (for example, CdS) whose light-receiving area gradually decreases along the moving direction of the arc.
Reference numeral 15 denotes a semicylindrical lens that focuses the light of the arc a onto the photoelectric conversion element 14. The light of the arc a generated at the welding part is transmitted to the conversion element 1 by the lens 15.
The light is focused in a rod shape on the light receiving surface 4, and a rod shaped arc image b is formed on this light receiving surface. Photoelectric conversion element 1
A power supply 17 is connected to both ends of the resistor 16 via a resistor 16, and an output F is taken out from both ends _t1 and _t2 of the resistor 16.

In the detector shown in FIG. 2, if the arc image b moves to the right in the drawing, the amount of light received by the photoelectric conversion element 14 decreases, so the resistance value of this conversion element increases. Therefore, a signal F corresponding to the relative position with respect to the arc light is obtained at both ends of the resistor 16. Since this signal F changes in the same way as signal F in Fig. 1,
By inputting the difference between the output F of the detector 3 in FIG. 3 and the reference signal R to the amplifier 6 in FIG. 1, the same operation as described above can be performed.

Figure 3 shows a case where two photoelectric conversion elements similar to those in Figure 2 are used, and the two photoelectric conversion elements 14, 14' are used.
are arranged side by side so that their directions are different, one photoelectric conversion element has a light-receiving area that gradually decreases along the X direction, and the other photoelectric conversion element 14' has a light-receiving area that gradually increases along the X direction. There is. These photoelectric conversion elements constitute a bridge circuit together with resistors 18 and 19, and a power supply 17 is connected between the power supply terminals of this bridge circuit. Note that this bridge circuit is adjusted so that it is balanced when the arc image b is located approximately at the center. In the case of this configuration, it is naturally unnecessary to use the reference signal R, and by inputting the output voltage _e0 of the bridge as it is to the amplifier 6 in FIG. 1, it is possible to perform the same tracking operation as described above. can.

FIG. 4 shows still another example of the structure of the arc photodetector 3. In the figure, 20 is a large number of photoelectric conversion elements such as phototransistors and small photoconductive elements (phototransistors in the illustrated example) A ₁ ,
A photosensitive element having A _{2 ,} . Diodes D ₁ to D _o and resistors r ₁₁ to _{r 1o} are connected in series to each element A ₁ to A _o of the photosensitive element 20, respectively, and these series circuits are connected to both ends of the power supply 17 via a resistor r _f . connected in parallel. When the photosensitive element 20 in FIG. 4 is irradiated with arc light, the conversion element irradiated with the arc light becomes conductive (or its resistance decreases) and a current flows, and this current causes a voltage F to be generated across the resistor r _f . arise. Therefore, by making the voltage F different depending on the irradiation position of the arc light by sequentially decreasing the resistance values of the resistors r ₁₁ to r _1o , the voltage F can be made to correspond to the relative position of the detector with respect to the arc. be able to. By inputting this voltage F together with the reference signal voltage R to the amplifier 6 shown in FIG. 1, it is possible to perform the operation exactly the same as that shown in FIG.

FIG. 5 shows an example of an application using the signal V corresponding to the speed of manual or semi-automatic welding detected by the present invention. In the figure, 12 is a welding power source, 13 is a power detection circuit, and the power detection circuit 13 includes, for example, a welding current detection circuit 131 that inputs the output of a current transformer 13a and outputs a signal I corresponding to the welding current, and a welding machine. A multiplier 132 receives the signal E corresponding to the output voltage or arc voltage of the above-mentioned signal I and outputs a signal P=EI corresponding to the electric power supplied to the welding electrode 2 and the workpiece 1. . 21 is a divider which inputs the above signal P and the signal V corresponding to the welding speed explained in FIG. 1 and outputs a signal EI/V corresponding to the welding heat input; 22 corresponds to the above signal EI/V. This is an indicator that displays signals. With this configuration, the display 22 shows the welding heat input per unit length of welding [Kilo-
Joule/cm] is displayed.

In FIG. 5, a power detection circuit 13 outputs a welding current detection circuit 131 which outputs a signal I corresponding to a welding current, and a signal corresponding to the product of a signal E corresponding to an arc voltage or a power supply voltage and a signal I. Although the power detection circuit is configured with a multiplier 132 for outputting power, the configuration of this power detection circuit can be changed as appropriate.
For example, when manual welding is performed using a welding power source with constant current characteristics, the signal I corresponding to the welding current value is approximately constant, so the signal P corresponding to the instantaneous power value is the signal corresponding to the arc voltage. It becomes E. In addition, when the welding power source 5 has a welding current setting device,
A signal corresponding to the output signal of this setting device may be used as the signal I corresponding to the welding current. Conversely, when performing semi-automatic welding using a welding power source with constant voltage characteristics, the signal E corresponding to the arc voltage value is approximately constant, so the signal P corresponding to the instantaneous power value varies depending on the welding current. A corresponding signal I is obtained. Furthermore, when an arc voltage setting device is present in the welding power source 5, a signal corresponding to the output signal of this setting device may be used as the signal E corresponding to the arc voltage.

Moreover, as the signal P corresponding to the instantaneous power value,
It is possible to detect leakage magnetic flux in the vicinity of the welding current carrying circuit with a coil and use its output signal, or to detect Joule heat generated in the welding circuit with a thermocouple and use its output signal. If the signal E corresponding to the arc voltage is not constant, the signal P corresponding to the instantaneous power can be obtained by combining these signals with the signal corresponding to the arc voltage or the output signal of the arc voltage setting device. Obtainable.

As the display 22 shown in FIG. 5, in addition to a meter using the principle of a voltmeter, a digital display having an A/D converter, a printer, or the like can be used. Further, as the indicator 22, a buzzer that issues an alarm when EI/V exceeds a preset value, a blinking indicator light, or the like may be used.

Furthermore, as shown by a broken line or a dashed-dotted line in FIG. The welding heat input can also be managed by controlling the output voltage, output current, etc. of the welding power source 12 by comparing it with the output of a setting device such as a welding current and welding voltage (not shown).

As described above, according to the present invention, there is an advantage that the welding speed of manual welding or semi-automatic welding can be quickly and easily measured.

It goes without saying that the present invention can be applied not only to manual or semi-automatic welding but also to automatic welding.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a welding speed detection device for implementing the method of the present invention, and FIGS. 2 to 4 are block diagrams showing different configuration examples of an arc photodetector used in the present invention, respectively. FIG. 5 shows an application example in which the signal V corresponding to the welding speed obtained by the welding speed detection method and device of the present invention is used to perform heat input management such as displaying welding heat input or controlling welding heat input. FIG. 1... Workpiece to be welded, 1a... Welding line, 2... Workpiece to be welded, 3... Arc light detector, 7... Drive source, 1
1...Speed detector.

Claims (1)

[Claims] 1. A welding speed detection method for manual or semi-automatic arc welding in which welding is performed while moving an arc generated from a welding electrode along a welding line of a workpiece, in which a signal corresponding to a relative position with respect to arc light is detected. An output arc photodetector is provided so as to be movable approximately along the welding line, and the moving speed of the arc photodetector is controlled by the output signal of the arc photodetector to cause the arc photodetector to move along the welding line. A welding speed detection method for detecting a welding speed by following the movement of the arc photodetector and obtaining a signal V corresponding to the movement speed of the arc photodetector. 2. In a welding speed detection device for manual or semi-automatic arc welding, which performs welding while moving the arc generated from the welding electrode along the welding line of the workpiece, the device is installed to move approximately along the welding line and is set relative to the arc light. an arc photodetector that outputs a signal corresponding to a position; and a drive source that changes the moving speed of the arc photodetector to follow the movement of the arc based on the output signal of the arc photodetector. and a speed detector that outputs a signal V corresponding to the moving speed of the arc photodetector that moves to follow the arc.