CN1186161C

CN1186161C - Arc stricking method for metal gas arc welding

Info

Publication number: CN1186161C
Application number: CNB021122636A
Authority: CN
Inventors: 华学明; 吴毅雄; 张勇; 蔡艳; 付延安; 石忠贤; 于乾波
Original assignee: Shanghai Jiao Tong University
Current assignee: Shanghai Jiao Tong University
Priority date: 2002-06-27
Filing date: 2002-06-27
Publication date: 2005-01-26
Anticipated expiration: 2022-06-27
Also published as: CN1385272A

Abstract

The present invention relates to a method for striking arcs of gas shielded arc welding with consumable electrodes, which belongs to the technical field of welding. The method comprises the following steps: in a primary slow wire feed stage, a welding wire is fed firstly at a speed which is 1/2 to 3/4 of a normally set wire feed speed, and the primary slow wire feed can be stopped when the end of the welding wire is in contact with a work piece; in a wire feed stopping stage, the welding wire can be fed continuously for a slight distance because of the inertia of a wire feed motor to ensure a reliable short circuit between the welding wire and the work piece, and the welding wire is fed downwards at a speed lower than the normal wire feed speed after a wire feed driving circuit is instantly switched on when electric arcs are judged by a welding power source to be formed; a secondary slow wire feed stage which follows after the electric arcs are stricken at the wire feed stopping stage is controlled in a period of 1 to 20 ms, and the process of striking is finished after stabilizing the electric arcs at the secondary slow wire feed stage; and after the electric arcs are stricken successfully, the secondary slow wire feed stage is switched to a stage at a wire feed speed set for normal welding. The method has high successful rate of striking, greatly reduces the possibility of exploding and breaking the welding wire, and realizes soft striking without splashing for the gas shielded arc welding with consumable electrodes.

Description

The striking method of molten electrode protected by gas arc welding

Technical field

What the present invention relates to is a kind of striking method of arc welding, and particularly a kind of striking method of molten electrode protected by gas arc welding belongs to welding technology field.

Background technology

The molten electrode protected by gas arc welding is after the work of welding starting switch, and the time of leading to a segment protect gas earlier in advance, welding wire is down sent to then, behind the contact workpiece, relies on short circuit current that welding wire and workpiece contact portion instant melting are produced electric arc.Find by literature search; Han Debin is in " Tohoku Electric Power technology "; write articles " arcing initiation success rate that improves welding machine " on 1994 (8); the molten electrode protected by gas arc welding striking technology that adopts in this article is when the beginning striking; wire feed rate is sent to downwards with slower speed by the circuit that designs, and rises to the wire feed rate that sets again behind the electric arc of waiting to ignite.Molten electrode protected by gas arc welder on the domestic market mostly adopts this kind to be referred to as the striking method of slow wire feed.But this method is to be under the prerequisite that welding wire sends to continuously, rely on the short circuit current filler wire to contact the end with workpiece and realize striking, when electrode extension longer, since welding wire when contacting with workpiece still at wire feed, the effect of wire feeding force makes welding wire extend bending outward, welding wire extends the middle part sectional area outward and diminishes and cause heat to concentrate to cause that welding wire becomes section quick-fried disconnected, simultaneously because the contact resistance of the effect welding wire of wire feeding force and workpiece is less, the heat fused that is unfavorable for the welding wire end, thereby be unfavorable for the striking success, this striking still is difficult to avoid quick-fried disconnected phenomenon and causes the striking failure.

Summary of the invention

The present invention is directed to the deficiencies in the prior art and defective; a kind of striking method of molten electrode protected by gas arc welding is provided; the slow wire feed of elder generation that the present invention adopts-stop wire feed-slow again wire feed changes the striking method of the wire feed rate that sets over to, quick-fried disconnected phenomenon when having solved striking then.

Description of drawings

Fig. 1 arc process schematic diagram

The earlier slow wire feed rate of Fig. 2 changes schematic diagram greater than the arc process wire feed rate of slow wire feed again

The earlier slow wire feed rate of Fig. 3 changes schematic diagram less than the arc process wire feed rate of slow wire feed again

The arc process wire feed rate that the slow again wire feed rate of Fig. 4 increases progressively continuously changes schematic diagram

The specific embodiment

As shown in Figure 1, Figure 2, Figure 3 and Figure 4, method of the present invention is specific as follows: behind the operating switch of the molten electrode protected by gas arc welding of closing, supply gas in advance, enter arc process then:

Step 1: earlier slow wire feed stage, 1/2～3/4 speed of the wire feed rate that the beginning feed rate of welding wire sets with normal welding is sent to downwards, be in the earlier slow wire feed stage, this moment, the source of welding current constantly detected weldingvoltage, welding current signal, according to weldingvoltage, welding current signal judges whether the welding wire end contacts with workpiece, and the source of welding current sends signal and stops earlier slow wire feed when the welding wire end contacts with workpiece;

Step 2: earlier the slow wire feed stage enters after finishing and stops the wire feed stage, this moment, welding wire was because the inertia of wire feeding motor also continues to send to slight distance, it is more reliable that the welding wire end is contacted with workpiece, the reliable short circuit of welding wire and workpiece simultaneously, the end that the rapid filler wire of the short circuit current that welding machine provides contacts with workpiece, because this moment, welding wire stopped to send to, the equilibrium problem of burn-off rate and wire feed rate does not take place, welding wire end moment of having melted produces the gap and forms arc space, when the weldingvoltage of the source of welding current by detecting, after welding current signal judges that electric arc has formed, moment is connected the wire feed drive circuit, welding wire is sent to downwards with the little speed of wire feed rate that sets than normal welding again, promptly is in the slow wire feed stage again;

Step 3: stop to enter after the wire feed stage, electric arc ignited again the slow wire feed stage, slow again wire feed of this stage is to set for the stable electric arc of just having set up that ignites, this section period is controlled between 1～20ms, for stablizing the slow again wire feed stage that the electric arc that just ignited is set, its slow wire feed pattern can be two kinds, a kind of is permanent slow wire feed, a kind of wire feed that increases progressively continuously, when adopting perseverance wire feed pattern at a slow speed, the wire feed rate in slow wire feed stage can be faster than the wire feed rate in elder generation's slow wire feed stage again, also can be slower, when employing increases progressively the wire feed pattern continuously, wire feed rate is to be increased to the wire feed rate that normal welding sets gradually continuously from zero, and striking finishes behind slow wire feed stage arc stability again;

Step 4: when above-mentioned steps 1, step 2, after the successful striking of step 3, slow again wire feed phase transition is to the normal wire feed stage.

The present invention has substantive distinguishing features and marked improvement; adopt the slow wire feed of elder generation of the present invention-stop wire feed-slow again wire feed; change the striking method of the wire feed rate that sets then over to; through a large amount of tests; the success rate of striking is high; significantly reduce the quick-fried disconnected possibility of welding wire, realized that the molten electrode protected by gas arc welding do not have the soft striking of splashing.

Claims

1. An arc striking method for melting gas shielded arc welding, which is characterized in that the method is as follows: after closing the working switch of melting gas shielded arc welding, gas is supplied in advance, and then enters the arc starting process:

Step 1: In the slow wire feeding stage first, the wire feeding speed starts to feed downward at a speed of 1/2~3/4 of the wire feeding speed set for normal welding. At this time, the welding power supply continuously detects the welding voltage, welding current Signal, according to the welding voltage and welding current signal, judge whether the end of the welding wire is in contact with the workpiece. When the end of the welding wire is in contact with the workpiece, the welding power supply sends a signal to stop and feed the wire slowly;

Step 2: After the end of the slow wire feeding stage, enter the stop wire feeding stage. Due to the inertia of the wire feeding motor, the welding wire continues to be fed for a small distance. At this time, the welding wire has stopped feeding, and a gap is formed at the end of the melted welding wire to form an arc space. When the welding power supply passes the detected welding voltage and the welding current signal judges that the arc has been formed, the wire feeding drive is turned on instantly. circuit, the welding wire is fed downward at a speed lower than the wire feeding speed set by normal welding, that is, it is in the slow wire feeding stage;

Step 3: Stop the wire feeding stage and enter the slow wire feeding stage after the arc is ignited. This period of time is controlled between 1 and 20ms, and its slow wire feeding mode can be divided into two types, one is constant slow wire feeding, and the other is continuous Incremental wire feeding, when the constant slow wire feeding mode is adopted, the wire feeding speed in the second slow wire feeding stage can be faster or slower than that in the first slow wire feeding stage, when the continuous incremental wire feeding mode is adopted, the wire feeding speed The wire speed is gradually and continuously increased from zero to the wire feeding speed set for normal welding. When the arc is stable in the slow wire feeding stage, the arc ignition ends;

Step 4: After the above step 1, step 2, and step 3 are successfully ignited, the slow wire feeding stage is switched to the normal wire feeding stage.