JPS58141861A - Arc welding method - Google Patents

Abstract

PURPOSE:To form good beads having uniform height at all times by controlling a welding current by detecting arc light penetrated to the back of a material to be welded and at the same time, controlling the controlled welding current to form surface beads of specified height. CONSTITUTION:The amount of arc light and the amount of radiant light from a preceding electrode welding wire 4 are detected by a photocell 5 provided on a backing strap 2, converted to a voltage value, added by an adder 7, and the differential voltage between the set voltage value of a back bead width setting device 8 is obtained by a comparator 9. This differential voltage is inputted to a welding current controller 10, and the welding current of a welding wire 4 is controlled to make the differential voltage to zero and back beads of specified shape are formed. This controlled welding current value is detected by a welding current detector 12, and compared with the set value of a surface bead height setting device 12'. The welding speed is controlled by a welding speed controller 17, the welding speed of succeeding electrode is controlled by a succeeding current controller 19 and the wire projection length is controlled by wire projection length controllers 20, 20' to make the differential voltage to zero.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a single-sided automatic welding method that can always obtain a predetermined surface bead shape regardless of variations in the groove condition.

Single-sided automatic welding is often used for welding large steel plates such as shipbuilding materials because sufficient penetration can be obtained by welding from one side without reversing the material to be welded, and a good bead can be formed. ing.

By the way, in order to form a good bead, the shape of the groove in the material to be welded must always be constant, but because the end face of the material to be welded is thermally deformed, for example, when it is cut, the shape of the groove is not necessarily constant. As a result, there was a problem in that the bead shape after welding was irregular.

The present inventors have conducted extensive research in order to solve the above-mentioned problems and develop a single-sided automatic welding method that can always form a good bead with a uniform height even if the groove condition fluctuates. .

The present inventors previously provided a light amount detector consisting of a plurality of photoelectric light-receiving elements on the side of the backing metal that comes into contact with the backing material in single-sided automatic welding, and used the photoelectric light-receiving elements to detect the welding material during welding. A method of receiving arc light penetrating the back surface and radiant light from the red-hot welding part, converting it into an electrical signal, and controlling the movement speed and horizontal position of the backing metal, as well as current, voltage, welding speed, etc. We have developed a method to control the welding parameters and control the back bead shape and arc drilling force by controlling heat input.

Fig. 1 is a vertical cross-sectional view of a single-sided automatic welding part showing an example of the above method, and Fig. 2 is a plan view of the backing metal, where ■ is a steel plate that is the material to be welded, 2 is the backing metal, and 3 is a plan view of the backing metal. A translucent backing material such as a glass fiber tape is interposed between the steel plate 1 and the backing metal 2, 4 is a welding wire, and the arrow indicates the welding direction.

A light amount detector consisting of a light receiving element 5 such as a photodiode, a phototransistor, or a CDS is embedded in the side of the backing plate 2 that is in contact with the backing material 3.

As shown in FIG. 2, four light-receiving elements 5 are embedded in the backing metal 2 at predetermined intervals on the right and left sides of the front and rear sides of the welding wire, respectively, from just below the welding wire in the direction of welding progress. The moving speed and horizontal position of the backing metal 2 are controlled so that the center of the arc generation position 6 is located near the center of the four light receiving elements 5.

The present inventors have proposed that the above-mentioned one or more light receiving elements 5
By controlling the welding current so that the amount of light received is constant, the width of the back bead can be made constant regardless of the groove condition. It was found that there is a proportional relationship with the surface bead height. In other words, even if the groove condition changes, if welding is performed so that the welding current is controlled to a predetermined current value depending on the thickness of the material to be welded, a surface bead with a constant height can be obtained. become.

This invention was made based on the above knowledge, and includes a light amount detector that detects the amount of arc light and radiation light of the welded part on the back side of the welded material, and In an arc welding method in which a welding material is welded with a welding electrode provided in a welding machine while a welding machine and the light intensity detector are moved synchronously along the welding machine, the arc light penetrating the back surface of the welding material and radiant light, or both, are received by the light amount detector, the amount of light is detected, and the welding current of the welding electrode is controlled based on the detected amount of light, and the value of the controlled welding current is detected. When there is only one welding electrode, at least one of the welding speed and the wire protrusion length of the welding electrode is adjusted so that the welding current value matches the set reference current value for forming a surface bead of a predetermined height. In addition, when there is a plurality of welding electrodes, the method is characterized in that at least one of the welding speed, the wire protrusion length of the welding electrodes, the welding type, and the current value of the welding electrodes whose flow is not controlled is controlled. It is something.

Next, an embodiment in which the present invention is applied to a single-sided welding method using two-electrode submerged arc welding will be described based on the block diagram of FIG. 3.

In the drawings, 4 is a welding wire of a leading electrode, 4' is a welding wire of a trailing electrode, 13 is a leading electrode nozzle, 13' is a trailing electrode nozzle, and the arrow indicates the welding direction.

11.11' is a welding power source whose one end is connected to the steel plate 1, and the leading electrode nozzle 13 is connected to the welding power source 11 by a conductor 15.
Furthermore, the trailing electrode nozzles 13' are respectively connected to the welding power source 11' by conductive wires 15'. Leading electrode nozzle 13
A welding current detector 12 is provided in the middle of a conducting wire 15 connecting the welding power source 11 and the welding power source 11 .

The leading electrode nozzle 13 can be moved vertically by an electrode nozzle driving motor 14, and the trailing electrode nozzle 13' can be moved vertically by an electrode nozzle driving motor 14', thereby controlling the protruding length of the welding wires 4, 4'. can do. 2 is a backing metal, 5 is four light-receiving elements that are light quantity detectors provided on the backing metal 2, and 3 is a transparent backing material.

In this invention, four light receiving elements 5 provided on the backing metal 2 detect the amount of arc light emitted from the welding wire 4 of the preceding electrode and the amount of radiant light from the red-hot part of the welding,
The detected amount of radiant light is photoelectrically converted into a voltage value, which is added by an adder 7, and then compared by a comparator 9 with a voltage value for achieving a predetermined back bead width preset by a back bead width setting device 8. Obtain the differential voltage. Next, this differential voltage is input to the welding current controller 10, and the welding current of the welding wire 4 of the preceding electrode is controlled so that the differential voltage becomes zero.

In this way, a back bead having a predetermined shape is formed.

Then, the welding wire 4 of the preceding electrode controlled as described above
The welding current value is detected by the welding current detector 12. As shown in the block diagram of FIG. 4, the detected current value detected by the welding current detector 12 is compared with the set current value set by the front bead height setting device 12' by a comparator 16 to determine the difference voltage. The differential voltage is controlled to be zero by one or more of the following means.

(1) The welding speed controller 17 controls the drive of the welding cart drive motor 18, that is, the welding speed.

(2) The trailing current controller 19 controls the welding power source 11' of the trailing electrode nozzle, that is, the welding current of the trailing electrode.

(3) The driving of the preceding electrode nozzle drive motor 14, that is, the protruding length of the welding wire of the preceding electrode is controlled by the preceding electrode wire+protrusion length controller 2o.

(4) The trailing electrode wire protrusion length controller 20' drives the trailing electrode nozzle drive motor 14', that is, controls the protrusion length of the welding wire of the trailing electrode.

The above control is performed in the 19th order. That is, if the detected current value detected by the welding current detector 12 is smaller than the set current value of the front bead height setting device 12',
Since the amount of deposited metal on the front bead is insufficient, either reduce the welding speed, or increase the current value of the trailing electrode or the length of the welding wire protruding from each electrode. On the other hand, if the detected current value is larger than the set current value, the amount of weld metal deposited on the front bead is excessive, so either increase the welding speed or increase the current value of the trailing electrode or the welding wire protrusion of each electrode. Reduce length. Furthermore, if the set current value and the detected current value are the same, it means that the amount of welded metal on the front bead is in an appropriate state.
Welding is performed while maintaining the welding speed, current value of the trailing electrode, and wire protrusion length at the current values.

Next, specific examples of the present invention will be described.

A steel plate having a thickness of 16 mm was welded by two-electrode submerged arc welding under the following conditions, with the groove shape being a V-groove of 50°.

(1) Wire diameter 4.8 m* 96 x 2 (
2) Leading electrode voltage: 36V (3) Trailing electrode voltage: 44V The back bead width was set to 15 to 16 mm using the back bead width setting device 8, and the current value of the leading electrode was controlled.

At the same time, the controlled current value is detected, and the welding speed and trailing electrode are adjusted so that the current value becomes 820A, which is the current value that can form an optimal surface bead when welding a steel plate with a thickness of 16 mm. The current value was controlled.

Table 1 shows the bead shape when the welding speed and the current value of the trailing electrode are controlled by the groove gap using the method of the present invention, along with a conventional example in which such control is not performed. .

Table 1 As is clear from Table 1 above, by the method of this invention,
As a result of controlling the welding speed and trailing electrode current based on changes in the amount of back bead arc radiation light depending on the size of the groove gap, a more uniform front bead shape can be achieved compared to conventional examples that do not perform such control. The shape of the back bead was also uniform.

FIG. 5 shows 600 A using a 4.011 Da wire at a voltage of 32 V and a speed of 35 cIrL/min.

This figure shows the wire melting speed when welding with a welding current of 700 A and 800 A with different wire protrusion lengths; the larger the wire protrusion length, the higher the wire melting speed. Therefore, it can be seen that the desired surface bead shape can be obtained by changing the protruding length of the wire according to the change in the welding current of the preceding electrode according to the method of the present invention.

Although the above-described embodiments have been described with reference to two welding electrodes, the same method can be used even with one welding electrode. In addition, when there is only one welding electrode, the welding speed and the protrusion length of the welding electrode are used as control factors, and control is performed using at least one of them. Further, in the case of welding electrode force number, welding current control is normally performed for the preceding electrode based on the above-mentioned light amount.

In addition to the single-sided arc welding method for forming a uranami bead, this invention also provides a steel sheet 1.1
It can also be effectively applied to an arc welding method that does not form a back bead in the welded part, and can be widely applied not only to submersor arc welding but also to gas shielded arc welding using a consumable electrode and various other types of welding.

As described above, according to the method of the present invention, a constant back bead shape can be obtained in single-sided arc welding regardless of fluctuations in the groove condition, and at the same time, the height of the front bead can be automatically kept constant. In addition, in arc welding that does not form a uranami bead, a constant penetration depth and constant bead height can be obtained regardless of fluctuations in the groove condition, etc.
Excellent industrial effects are brought about.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a single-sided automatic welding part showing the control means using a photoelectric light receiving element, Fig. 2 is a plan view of the backing metal, and Fig. 3 is a plan view of the backing metal.
The figure is a block diagram when this invention is applied to a single-sided welding method using two-electrode submerged arc welding, Figure 4 is a block diagram of controlling the amount of welded metal on the front bead according to this invention, and Figure 5 is a diagram showing wire protrusion length and wire melting. FIG. 6, which is a diagram showing the relationship with speed, is a longitudinal cross-sectional view of a welded part where no back bead is formed. In the drawings, 1... steel plate, 2... backing metal, 3... backing material, 4,
4'... Welding wire, 5... Light receiving element, 6... Arc generation position, 7... Adder, 8... Back bead width setting device, 9... Comparator, 10...・Welding current controller, 1
1.11'... Welding power source, 12... Welding current detector, 12'... Front bead height setting device, 13.13'...
・Electrode nozzle, 14.14'...Electrode nozzle driving motor, 15,15'...Conducting wire, 16...Comparator, 1
7... Welding speed controller, 18... Welding cart drive motor, 19... Trailing current controller, 20.20'...
Wire protrusion length controller. Applicant: Nippon Steel Tube Co., Ltd. Agent: Keitabe Tsutsumi (1 person) -29 Wire protrusion length Cmm)

Claims (4)

[Claims] (1) A light intensity detector that detects the light intensity of the arc light and radiant light of the welded part is placed on the back side of the welded material, and the welding machine and the light intensity detector are placed along the groove of the welded material. In an arc welding method in which the material to be welded is welded by a welding electrode provided on a welding machine while moving the material synchronously, the arc light and/or the radiation light that penetrates the back surface of the material to be welded is A detector receives the light and detects the amount of light, controls the welding current of the welding electrode based on the detected amount of light, and detects the controlled welding current value so that the welding current value reaches a predetermined height. controlling at least one factor of welding speed, wire protrusion length of the welding electrode, and current value of the welding electrode in which the welding current is not controlled so as to match a set reference current value for forming a surface bead; An arc welding method characterized by: (2) Claim 1 (
The arc welding method described in item 1). (3) Claim (1), which is characterized in that the method mainly detects and controls the amount of radiant light from the molten pool of the material to be welded.
The arc welding method described in ). (4) The arc welding method according to claim (1), characterized in that the amount of radiation light from a weld bead of the welded material is mainly detected and controlled.