JPH08229684A - Gas shield consumable electrode type arc welding method - Google Patents

Abstract

(57) [Abstract] [Purpose] Using a CO ₂ gas mixed with a gas with a relatively small potential gradient (for example, Ar) and changing the mixing ratio of the gas prevents the occurrence of arcing defects at the start of arc welding and reduces gas costs. In addition, a good bead appearance is obtained at the welding start point and the welding end point. [Structure] At the start of welding, an arc try is performed using a shield gas having a smaller potential gradient than that of CO ₂ gas, and after confirmation of arc generation, the mixing ratio of CO ₂ gas is gradually increased at a preset gradual increase ratio, and CO ₂ welding is performed. , And immediately before the end of welding,
The mixing ratio of the shield gas having a small potential gradient is gradually increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas shield consumable electrode type arc welding method in arc welding, and more particularly to a welding method at the start of welding and at the end of welding.

[0002]

2. Description of the Related Art Conventionally, in a gas shield consumable electrode type arc welding method, a shield gas having a constant mixing ratio is used from the start of welding to the end of welding mainly for the purpose of protecting the welded portion from the surrounding atmosphere. In particular, CO ₂ : 100% gas is used in welding where importance is placed on penetration, and since CO ₂ gas is cheaper than Ar gas, CO ₂ gas is generally used. On the other hand, in Japanese Examined Patent Publication No. 60-35230 (p4), carbon dioxide gas and a mixed gas of carbon dioxide gas and argon gas are alternately supplied to alternately change the arc voltage to divide the molten pool into small areas. Welding is disclosed.

[0003]

However, in the conventional method, when a shield gas having a relatively large potential gradient, such as CO ₂ welding, is used, an arcing defect is likely to occur at the welding start point, and the welding start There was a problem that it was difficult to obtain a good bead appearance at the welding point and the welding end point. Further, the problem of bead appearance can be solved by a welding method such as MAG welding in which a gas having a relatively small potential gradient is mixed, but since a gas having a small potential gradient such as Ar is used from the start to the end of welding, the cost of the gas itself is reduced. There was a problem that became large. Further, the technique of Japanese Patent Publication No. 60-35230 cannot be applied at the start of welding and the end of welding. Therefore, the present invention is
By using a gas (for example, Ar gas) having a relatively small potential gradient only as a shield gas for a preset increasing time after the arc is generated, it is possible to prevent an arc generation defect at the start of arc welding and reduce the gas cost. _It is an object of the present invention to provide an arc welding method using _two gases and using a gas having a small potential gradient again at the end of welding to obtain a good bead appearance and at the same time reduce gas costs.

[0004]

In order to solve the above problems, the present invention performs arc try using a shield gas having a potential gradient smaller than that of CO ₂ gas at the start of welding,
After confirming the occurrence of an arc, the mixture ratio of CO ₂ gas is gradually increased at a preset gradually increasing ratio to shift to CO ₂ welding, and the mixture ratio of shield gas having a small potential gradient to CO ₂ is gradually increased immediately before the end of welding. Is.

[0005]

[Operation] Since a shield gas having a smaller potential gradient than CO ₂ gas is used at the start of welding, an arc is easily generated,
When an arc occurs, the mixing ratio of CO ₂ gas is increased,
Shift to CO ₂ welding with low gas cost. Since a shield gas having a smaller potential gradient than CO ₂ gas is used at the end of welding, the arc is extinguished gently, and a good bead appearance can be obtained at the end of welding.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a flow chart of the present invention, FIG. 2 is an explanatory view of a method of changing a mixing ratio of shield gas at the start of welding, and FIG. 3 is a schematic view of an apparatus for carrying out an embodiment of the present invention. First, an outline of an apparatus for carrying out an embodiment of the present invention will be described with reference to FIG. The welding machine 1 uses the torch 4 for welding current,
The welding voltage is supplied, the wire feeding speed command is output to the wire feeding device 3 that feeds the wire 2 to the torch 4, and the solenoid valves 5 and 6 are further controlled. The solenoid valve 5 is a solenoid valve that adjusts the flow rate of the Ar gas 7, and the solenoid valve 6 is the CO ₂ gas 8
Is a solenoid valve for adjusting the flow rate of.

Next, the flow of the present invention will be described step by step with reference to FIG. (STEP1) Confirm the arc generation at the welding start point. (STEP2) STEP1 If you can not see arcing _{in, Ar: 80%, CO 2} : 20% of consisting mixing ratio MAG gas, or performs arc trie with Ar gas. (STEP3) When the arc generation is confirmed in STEP1, in order to shift to CO ₂ welding as shown in FIG. 2A, the solenoid valve of CO ₂ gas is opened and the solenoid valve of Ar gas is closed to start welding. Then, the series of processing of is ended. (STEP 4) It is confirmed that the welding time (t) is equal to or longer than the time (T−ΔT) before the welding end time (T) by the set time (ΔT). (T ≧ T−ΔT) (STEP5) When t ≧ T−ΔT cannot be confirmed in STEP4, CO ₂ welding is continued (STEP6) When t ≧ T−ΔT is confirmed in STEP4, it is shown in FIG. 2 (b). In order to shift to such MAG welding, the electromagnetic valve for MAG gas is opened and the electromagnetic valve for CO ₂ gas is closed to end the series of processes at the start of welding.

In the above embodiment, the predetermined welding time is stored in advance and the actual welding time is compared to grasp the time immediately before the end of welding. However, it is not the time but the position or distance data. It may be possible to grasp the time immediately before the end of welding. Therefore, a memory for storing time (or position or distance), means for detecting actual welding time (or position or distance), and comparison means are provided in the welding machine 1. Further, in the above embodiment, the welding is completed after the mixing ratio is completely stabilized at the end of the welding, but it may be ended during the change of the mixing ratio. Further, in the present embodiment, the welding machine 1 issues each control command as described above,
When the present invention is implemented using a welding robot, the welding robot control device may have a function of issuing such a control command.

[0009]

As described above, according to the present invention, paying attention to the difference in the potential gradient of the shield gas, the gas having a small potential gradient is mainly used when the arc is generated, and the potential gradient is not confirmed after the arc confirmation. Since CO ₂ welding, which is large but has low gas cost, is switched to welding that mainly uses gas with a small potential gradient when extinguishing arc, it is possible to prevent arcing defects and reduce gas cost, and a good bead appearance at the end of welding. It is possible to achieve the above and reduce gas costs.

[Brief description of the figure]

FIG. 1 is a flowchart of an embodiment of the present invention.

2A and 2B are explanatory views of the operation of the present invention, in which FIG. 2A is an explanatory view at the start of welding and FIG.

FIG. 3 is a schematic diagram of an apparatus for carrying out an embodiment of the present invention.

[Explanation of symbols]

1 Welder 2 Wire 3 Wire feeder 4 Torch 5 Solenoid valve 6 Solenoid valve 7 Ar or MAG gas cylinder 8 CO ₂ gas cylinder

Front page continued (72) Inventor Hajime Fujii Hajime Kurosaki No. 2 No. 1 Yasukawa Electric Co., Ltd., Hachiman Nishi Ward, Kitakyushu, Fukuoka (72) Inventor Nobuharu Okumura No. 2 No. 1 Kurosaki Joishi, Hachiman Nishi Ward, Kitakyushu, Fukuoka Yaskawa Co., Ltd. Inside the electric machine

Claims (3)

[Claims] 1. In a CO ₂ gas shield consumable electrode type arc welding method, an arc try is performed at the start of welding using a shield gas having a smaller potential gradient than CO ₂ gas,
A CO ₂ gas shield consumable electrode type arc welding method, which comprises gradually increasing a mixing ratio of CO ₂ gas at a preset increasing ratio after confirming the occurrence of an arc, and shifting to CO ₂ welding. 2. A CO ₂ gas shielded consumable electrode arc welding method, CO ₂ gas shielded consumable electrode, characterized in that for increasing the mixing ratio of the small shield gas of potential gradient than in the CO ₂ gas to the welding end just before Arc welding method. 3. In a CO ₂ gas shield consumable electrode type arc welding method, an arc try is carried out at the start of welding using a shield gas having a smaller potential gradient than CO ₂ gas,
After confirming the occurrence of arc, gradually increase the mixing ratio of CO ₂ gas at a preset increasing ratio, and shift to CO ₂ welding.
A CO ₂ gas shield consumable electrode type arc welding method characterized in that the mixing ratio of the shielding gas having a small potential gradient is gradually increased immediately before the end of welding.