JPH0417749B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) Welding that has a wire feeding mechanism that feeds a welding wire at a constant speed, and performs welding while moving a welding torch so as to maintain a constant wire protrusion length. The present invention relates to a method and apparatus for automatically controlling welding conditions for an automatic welding machine having a speed control mechanism.

(Prior art) An automatic welding machine has a wire feeding mechanism that feeds a welding wire at a constant speed, and a welding speed control mechanism that moves the welding torch while keeping the wire protrusion length constant. The welding method used is
The electroslag welding method and its equipment proposed in Japanese Patent Application Laid-open No. 156884, 1982, "Performance of Wire Vibration Type Electrogas Welding Parts" presented at the 1981 Welding Society Spring Conference - Wire Vibration Type Electrogas Welding Method Welding methods such as the vertical electrogas welding method introduced in the study (2nd report) and the narrow gap horizontal automatic welding method proposed in JP-A No. 54-23049 are generally known. It is being

As an example, a vertical electrogas welding method will be explained. FIG. 6A is a side view of the welding method seen from the side, and FIG. 6B is a plan view seen from above.

In FIG. 6, reference numeral 1 indicates a base material, 2 indicates a fixed backing material that is in contact with the back surface of the groove, and 3 indicates a sliding copper pad with a shield gas nozzle that is in contact with the surface of the groove. The welding wire 4 is inserted through the tip 5 into the space formed by these, and the tip of the welding wire is swung in the direction of the plate thickness, that is, in the direction of arrow A in FIG.
is formed, and the groove is welded by -pass-run.

At this time, the change in the distance P between the tip 5 and the molten metal surface 7 of the weld metal 6 shown in FIG. 6A is as follows, since the wire is fed at a constant speed. It appears as a change in welding current. Therefore, the welding cart (not shown) on which the sliding copper butt 3 and the tip 5 are mounted is designed to keep the welding current constant, that is, the wire protrusion length defined by the distance P between the tip and the metal surface. The vehicle is controlled to maintain a constant temperature and runs automatically. The welding traveling trolley's traveling method is that if the wire protrusion length is longer than the set standard value, the welding current will be lower than the reference value, so this will be detected and the vehicle will run at a low speed, and the wire protrusion length will be set. If it is shorter than the specified reference value,
Since the welding current becomes higher than the standard value, this is detected and the machine runs at high speed to keep the length of the wire protruding constant.

In this welding method, welding metal is cast into the groove and welded, so when the wire feeding speed is constant, the welding speed varies depending on the variation in the cross-sectional area of the groove. In addition, with this welding method, if the welding speed is too high, there is a risk of weld cracking, and if the welding speed is slow, the work efficiency and the toughness of the heat-affected zone will be reduced, so the operator must always be careful during welding work. Measure the groove width, calculate the groove cross-sectional area from the measured value, and adjust the wire feeding speed to a value determined in advance by experiment to obtain the appropriate welding speed based on the calculation result. Welding conditions such as welding current and welding voltage are set to suit the wire feeding speed determined through experiments. Therefore, when welding long pieces, a great burden is placed on the operator.

(Problems to be Solved by the Invention) The present invention solves the above problems, uses the welding speed as a parameter, and automatically adjusts the welding conditions accordingly, thereby obtaining stable welding results. The object of the present invention is to provide a method and device for automatically controlling welding conditions that reduce the burden on workers.

(Means for Solving Problems) The gist of the present invention is as follows: (1) A wire feeding mechanism that feeds a welding wire at a constant speed is provided, and the welding is performed so that the wire protrusion length is kept constant. A welding method using an automatic welding machine having a welding speed control mechanism that performs welding while moving a torch, characterized by detecting a welding speed and automatically controlling welding conditions based on the detected value of the welding speed. and (2) a wire feeding mechanism that feeds the welding wire at a constant speed, and a welding speed control mechanism that welds while moving the welding torch so as to keep the wire protrusion length constant. In an automatic welding machine, a welding speed detector used as a means for detecting the welding speed, a converter that converts the output signal of the welding speed detector into an average welding speed, and a converter based on the average welding speed converted by the converter The automatic welding condition control device is characterized in that it is equipped with either a comparator or a calculator having the function of determining welding conditions by comparing the welding conditions with a reference value set in advance.

The present invention will be explained in detail below.

(Function) First, FIG. 1 shows a schematic diagram of a welding apparatus equipped with an automatic welding condition control device of the present invention. 1 is a base material, 2 is a fixed backing material, and 3 is a sliding copper pad. A chip 5 is positioned at the center of the groove surrounded by these, and a welding wire 4 is opened through the chip 5. It has been sent to Sakiuchi and welding is being carried out. At the same time, a welding cart 8 carrying a sliding copper dowel 3 and a chip 5 is automatically traveling on a rail 9 as welding progresses. At this time, a welding speed detector 10 attached to the welding cart 8 and arranged so as to be in contact with the rail 9 outputs a traveling signal for the welding cart 8. As explained above, the welding cart 8 is running at high or low speeds that change moment by moment so as to keep the protruding length of the wire constant, so the running signal output from the welding speed detector 10 also corresponds to this. becomes.

The running signal is converted into a signal representing the average welding speed through a converter 11, and the signal is input to a comparator or calculator 12. In the case where 12 is a comparator, the signal is compared with a reference value previously determined and set by experiment, and appropriate welding conditions such as wire feeding speed, welding current, welding voltage, etc. are selected.

Note that 13 is a welding power source, and 14 is a wire feeder. In addition, when 12 is a computing unit, the signal is compared with a reference value determined and set in advance through experiments, and the difference between the reference value and the signal is processed, and the appropriate wire feeding speed and welding are determined. Determine welding conditions such as current and welding voltage.

With this method, appropriate welding conditions can be automatically determined from the welding speed.

Next, the apparatus of the present invention will be explained.

A generator can be used as the welding speed detector 10 in FIG. When welding is performed using this device under welding conditions A1, which is a set of wire feeding speed _W1 (unit: m/min), welding current _I1 (unit A), and welding voltage _E1 (unit V ₎ , the generator The output signal is generally a voltage signal E as shown in Figure 2, since the welding cart is running at high speed or low speed while changing moment by moment so as to keep the length of the wire protruding constant as described above. It's giving out _S0 .

The voltage signal E _S0 is input to the converter 11. In this case, it is possible to use the circuit shown in FIG. 3, which is comprised of a resistor 15 and a capacitor 16, which are generally used as an integrating circuit. converter 11
, the voltage signal E _S0 is smoothed and becomes the voltage signal E _S1 shown in FIG. The voltage signal E _S1 is a voltage signal indicating the average welding speed.

The voltage signal E _S1 is input to the comparator 12. In the comparator 12, the voltage signal E _S1 is used as a reference value and compared with a high reference value E _sn and a low reference value E _so, which have been determined in advance through experiments. Voltage signal E _s1
is between the high standard value E _sn and the low standard value E _so , the welding condition A ₁ remains unchanged. At this time, as shown in Fig. 1, the groove width B becomes narrower, the cross-sectional area of the welding groove decreases, and the welding speed increases, and if the voltage signal E _s1 , which is the welding speed signal, exceeds the high standard value E _sn , the adjustment is made in advance. Then, welding is continued by selecting welding condition A ₀ , which is a set of wire feeding speed W ₀ , welding current I ₀ , and welding voltage E ₀ that have already been set.

In addition, as the groove width B becomes wider, the welding groove cross-sectional area increases and the welding speed becomes slower, and when the voltage signal E _s1 , which is the welding speed signal, falls below the low reference value E _so , the pre-adjusted and set Then, welding is continued by selecting welding condition _A2 , which is a set of wire feeding speed _W2 , welding current _I2 , and welding voltage _E2 .

At this time, the welding conditions that have been adjusted and set in advance are increased in addition to A ₀ , A ₁ , and A ₂ .
By setting A ₀ , A ₁ , A ₂ , A ₃ , …A _o ,
Welding conditions can be changed more precisely, and welding can be performed more smoothly.

Also, set the reference values E _sn and E _so to different values: a value corresponding to welding condition A ₀ , a value corresponding to welding condition A ₁ , and a value corresponding to A ₂ , A ₃ , ... A _o . According to
Appropriate welding speed and welding conditions under welding condition A ₀
It is also possible to set the appropriate welding speed separately, such as the appropriate welding speed for A ₁ , the appropriate welding speed for A ₂ , A ₃ , ... A _o , and the appropriate welding speed is a function of welding speed, welding current, and welding voltage. The expressed welding heat input can also be controlled.

In other words, when a welding current I _o for a certain welding condition A _o , a welding current I _n higher than the welding voltage E _o , and a welding condition A _n for the welding voltage E _n are selected, the welding speed is higher than the welding speed corresponding to the welding condition A _o . Since the welding speed can be set, when the welding speed is constant, the increase in welding heat input, which increases in proportion to the product of welding current and welding voltage, can be suppressed by increasing the welding speed. It is possible.

Conversely, under certain welding conditions _Ao , welding current _Io , welding current _Ip lower than welding voltage Eo, welding voltage _{Ep ,} welding conditions
Even when A _p is selected, it is possible to set a welding speed lower than the welding speed corresponding to welding condition A _o , and it is possible to suppress the decrease in welding heat input to a low level.

Next, a case where 12 in FIG. 1 is an arithmetic unit will be explained.

When 12 is an arithmetic unit, the voltage signal E _s1 output from the converter 11 is compared with a preset reference value E _sk and the difference between E _sk and E _s1 is determined experimentally. The wire feed speed W ₁ , welding current I ₁ , and welding voltage E ₁ set under welding condition A ₁ are calculated using the following calculation formula.
It is possible to determine the increase or decrease of

In this case as well, the increase/decrease in the reference value E _sk is adjusted by arithmetic processing with respect to the increase/decrease in the wire feed speed _{W 1 ,} welding current I ₁ , and welding voltage E ₁ set in the welding condition A 1 By doing this, it is possible to set separate appropriate welding speeds for each welding condition, and as described above, it is also possible to control the welding heat input.

Next, a case where an encoder is used as the welding speed detector 10 in FIG. 1 will be described.

In this device, the wire feeding speed W ₁ (unit: m/
min), welding current I ₁ (unit A), and welding voltage E ₁ (unit V) as a set. When welding is performed under welding conditions A ₁ ,
The output signal of the encoder is generally as shown in Fig. 5, since the welding cart is running at high or low speed while changing every moment to keep the length of the wire protruding constant as described above. It outputs pulse signals with temporal differences in pulse signal density. The pulse signal is input to the converter 11. In this case, the converter 11 may be an integrator that integrates the pulse signals. converter 11
Then, the pulse signal is integrated per unit time. This integrated value _K1 indicates the average welding speed per unit time. The unit time for integration is 10 seconds ~
200sec is appropriate. If it is shorter than 10sec,
Affected by temporal differences in pulse signal density,
The integrated value _K1 , which indicates the average welding speed, fluctuates greatly,
This is undesirable because welding conditions constantly change. or
If it is longer than 200 seconds, the timing of changing the welding conditions will be delayed by the cumulative time, and if the groove width B in Figure 1 changes suddenly and the welding speed changes suddenly, the welding conditions will not be changed. Unable to follow and undesirable. Next, the integrated value K ₁ is input to the comparator 12 . In the comparator 12, the integrated value _K1 is used as a reference value and compared with a high reference value _Kn , which has been determined and set in advance through experiments, and a low reference value _Ko .

At this time, the integrated value K ₁ is the high reference value K _n and the low reference value
If it is between K _o , welding condition _A1 remains unchanged.
At this time, in Fig. 1, the groove width B becomes narrower, the cross-sectional area of the welding groove decreases, and the welding speed increases.
When the integrated value K ₁ , which is the welding speed signal, exceeds the high standard value K _n , the wire feeding speed W ₀ , welding current I ₀ , welding voltage
Select welding condition A ₀ with E ₀ as one set and continue welding.

In addition, as the groove width B becomes wider, the welding groove cross-sectional area increases and the welding speed becomes slower, and when the integrated value _K1 , which is a signal of the average welding speed, falls below the low reference value K _o , it is adjusted in advance, Welding condition A 2 is selected, which is a set of wire feeding speed W ₂ , welding current I ₂ , and welding voltage E _{2 that} have already been set, and welding is continued.

At this time, the welding conditions that have been adjusted and set in advance as described above are not only A ₀ , A ₁ , A ₂ but also increased in number and set to A ₀ , A ₁ , A ₂ , A ₃ , ...A _o This allows for more detailed changes in welding conditions and smoother welding.

Also, as above, the reference values K _n and K _o are set to welding conditions A ₀
The value corresponding to the welding condition A ₁ , the value corresponding to A ₂ ,
By setting values corresponding to A ₃ , ... A _o and separate values, the appropriate welding speed under welding condition A ₀ , the appropriate welding speed under welding condition A ₁ , A ₂ ,
A ₃ ,...A suitable welding speed at A _o , etc.
Appropriate welding speeds can be set separately, and welding heat input, which is a function of welding speed, welding current, and welding voltage, can also be controlled.

Next, a case where 12 in FIG. 1 is an arithmetic unit will be explained.

When 12 is an arithmetic unit, the integrated value K ₁ output from the converter 11 is compared with a preset reference value K _k , and the difference between K _k and K ₁ is determined experimentally. By performing arithmetic processing using the calculation formula, it is possible to determine the increase/decrease in the wire feed speed W ₁ , welding current I ₁ , and welding voltage E ₁ set under welding condition A ₁ , and always perform appropriate welding. Conditions can be set. In this case, wire feeding speed W ₁ set under welding condition A ₁ ,
By adjusting the increase/decrease in the reference value K _k through calculation processing with respect to the increase/decrease in the welding current I ₁ and the welding voltage E ₁ , it is possible to set separate appropriate welding speeds for each welding condition, and as described above. Welding heat input can also be controlled.

As explained above, according to the present invention, suitable welding conditions can be automatically determined.

In addition, as a welding speed detector, a generator,
The sensor is not limited to an encoder, but may be any device that can detect the welding speed, and may be a detector using an optical sensor or a detector using an ultrasonic sensor.

Furthermore, the mounting position of the welding speed detector is not limited to the position where it is attached to the welding trolley and is in contact with the rail, but may be mounted at any position as long as it can detect the traveling speed of the welding trolley.

Next, the present invention will be explained based on examples.

(Example) Using the welding equipment of the present invention, using a flux-cored wire with a wire diameter of 1.6 mm, a plate thickness of 20 mm, a groove angle of 34 degrees, and a surface groove width of 16 mm, welding conditions were changed as welding speed reference values. , a high standard value of 14 cm/min and a low standard value of 10 cm/min are set, and the welding conditions are: wire feeding speed 13 m/min, welding current 350 A,
Welding condition A ₀ is welding voltage 38V, welding condition A ₁ is wire feeding speed 15m/min, welding current 380A, welding voltage 40V, welding condition A ₂ is wire feeding speed 17m/min, welding current 410A, welding voltage 42V. , set in advance as, and at the start of welding, select welding condition A ₁ , shielding gas:
When vertical electrogas welding was started with CO ₂ 30/min and DC reverse polarity, the average welding speed was 11.7 cm/min at the beginning, and welding condition A ₁ remained unchanged. As welding progresses, the surface groove width decreases by 2mm near the welding center, and at the point when it reaches 14mm, the average welding speed exceeds the high standard value of 14cm/min, and welding condition A ₀ is automatically selected. The welding speed at this time was 12.2 cm/min. Next, as it approaches the end, the groove width widens, and when the surface groove width returns to the original 16 mm, the average welding speed is the low standard value 10
cm/min, welding condition _A1 was automatically selected. As welding progresses further and the surface groove width widens by 2 mm to 18 mm, the average welding speed again falls below the low standard value of 10 cm/min, and welding condition A ₂ is automatically selected, increasing the average welding speed to 11.2 cm. /min, welding is completed and the target welding speed is within the range (10cm/min).
min ~ 14cm/min), welding could be carried out smoothly.

(Effects of the Invention) As explained above, according to the present invention, welding conditions can be automatically controlled, the burden on the worker can be greatly reduced, and stable welding can be performed. The value is high.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an outline of the welding device of the present invention, FIG. 2 is a waveform diagram showing a signal of a welding speed detector, and FIG. 3 is a circuit diagram showing an embodiment of a converter.
Figure 4 is a diagram showing the average welding speed signal, Figure 5 is a diagram showing the signal of the welding speed detector, Figure 6A is a side view showing the vertical electrogas welding method, and Figure 6B is a diagram showing the signal of the welding speed detector. is its plan view. 1... Base material, 2... Fixed backing material, 3... Sliding copper backing material,
4... Welding wire, 5... Chip, 6... Welding metal,
7... Hot water surface, 8... Welding trolley, 9... Rail, 10...
Welding speed detector, 11... Converter, 12... Comparator or calculator, 13... Welding power source, 14... Wire feeder, 15... Resistor, 16... Capacitor, P... Wire protrusion length, B... Surface bevel width.

Claims (1)

[Scope of Claims] 1 Automatic welding that has a wire feeding mechanism that feeds a welding wire at a constant speed, and a welding speed control mechanism that performs welding while moving a welding torch so as to keep the wire protrusion length constant. 1. A method for automatically controlling welding conditions, which comprises detecting a welding speed in a welding method using a welding machine, and automatically controlling welding conditions based on the detected value of the welding speed. 2. In an automatic welding machine that has a wire feeding mechanism that feeds the welding wire at a constant speed and a welding speed control mechanism that welds while moving the welding torch so that the wire protrusion length is kept constant, A welding speed detector used as a detection means, a converter for converting the output signal of the welding speed detector into an average welding speed, and a reference value set in advance based on the average welding speed converted by the converter. 1. An automatic welding condition control device comprising either a comparator or a calculator having a function of comparing and determining welding conditions.