Second guarantee welding, how is the second guarantee welding vertical welding

Key points: pay attention to the combination of current and voltage, do not pull welding, should push welding, so as to increase the tensile strength.

Second, welding operation technology and precautions:

1. Due to the special manufacturing process of flux-cored welding wire, the appearance of the welding wire is easy to rust, and the powder is easy to absorb moisture, so it is necessary to pay attention to proper storage and storage. Before using the welding wire, carefully check whether there is rust on the surface of the welding wire, and confirm that the welding wire without rust can be used.

250 300°C drying, but drying the wire has certain difficulties. If you use a corroded or moisture-absorbing wire for welding, it is easy to appear porosity on the surface of the weld.

2. The flux-cored wire has small spatter, stable arc and a large range of parameter matching, but it takes a certain amount of time to adjust in order to obtain the most ideal parameter matching. When the parameters are not properly matched, there will be a non-axial excess of large melt droplets, resulting in large metal sputters and occasionally a rotating arc. When the parameters are well matched, the arc is soft and stable, and the spatter is small.

3. Single-sided welding and double-sided forming technology has extremely high requirements for the steel plate assembly gap and assembly misalignment, so the blunt edge grinding should be carefully done before welding, and the assembly clearance and assembly misalignment should be strictly controlled, and the amount of assembly misalignment should not be sloppy.

Fourth, the current should be adjusted on the arc test plate in advance, and the test welding should not be adjusted directly on the test plate. The left-hand welding method is used for welding.

5. It is more difficult to use flux-cored wire for single-sided welding and double-sided forming than to use solid-core wire for single-sided welding and double-sided forming, but the use of flux-cored wire for single-sided welding and double-sided forming, the back of the weld is smooth and the forming is beautiful. The operation method adopts the method of combining arc extinguishing welding and arc welding to ensure welding penetration and avoid welding penetration; Because the bottom of the flat welding position cannot be judged only by the size of the melt hole to judge the residual height of the back, in many cases the size of the melt hole remains the same, but there is already a large welding tumor on the back. Generally, the brightness of the weld pool is used to judge the residual height of the back of the weld.

1) CO2 semi-automatic gas shielded welding process This process is suitable for low-carbon steel and low-alloy high-strength steel welding of various large-scale steel structure engineering, its welding productivity is high, the crack resistance is good, the welding deformation is small, the deformation range is large, and the welding of thin plates and medium and heavy plates can be carried out. One. Welding Preparation 1

Before welding, joint cleaning requires that burrs, oil, rust, dirt, and oxide scale that affect the quality of the weld within 30mm on both sides of the groove must be cleaned. 2.When the construction environment temperature is lower than zero or the carbon equivalent of the steel is greater than that, and the structural rigidity is too large, and the object is thicker, preheating measures should be adopted when the object is thicker, the preheating temperature is 80 100, the preheating range is 5 times the thickness of the plate, but not less than when the thickness of the workpiece is greater than 6mm, in order to ensure the welding penetration strength, the butt edge of the plate should be cut V-shaped or X-shaped, the groove angle is 60 °, the blunt edge p is 0 1mm, and the assembly clearance B is 0 1mm; When the plate thickness difference is 4.

It depends on your welding position If it is a full-position weld, the current is between 100 and 200 if the plate is not thick. Voltage in 18 to 25It mainly depends on the performance of your welder and the welding wire used.

2) How to adjust the welding current of the second welding technology. The arc striking position of the second protection welding: generally the arc is triggered at 15-20mm at the beginning of the welding end, and the normal welding is from the end, which is designed according to the distance of the thermal ionization of gas ionization, because the higher the temperature, the easier it is to be thermally ionized, and the arc is easy to generate.

It's called: preheating arc starting. Rendering.

Generally, the current is coarse and fine, and the coarse adjustment is 1 gear, 2 gears, and the fine adjustment has 10 gears that are proportional to the wire feeding speed, the more crisp the welding sound, the better the welding effect, and the specific current adjustment has a formula. It depends on the thickness of the welding base metal and adjusts, the voltage is proportional to the current, the voltage is too high and the spatter will be more, and if it is too low, the welding wire and the base metal will not melt. 3) How to operate the technology of two-guarantee welding Left welding, current and voltage are well matched, the arc is stably burned, and there is a small molten ball at the end of the wire that is slightly larger than the diameter of the wire.

As for how thick the base metal is and how much current to use, you can only master it in practice. Second, the welding torch is lowered and the protective gas is opened larger, generally using the left and right swing or forward and backward swing mode, and the welding is pushed forward. Keep your hands steady.

The principle of the second welding is that the welding wire and the weldment are used as two electrodes to generate an electric arc, and the heat of the arc is used to melt the metal, and carbon dioxide gas is used as the shielding gas to protect the arc and the molten pool, so as to obtain a good welding joint.

1. The full name of the second protection welding is: carbon dioxide gas shielded welding, which is a welding method.

2. This welding method has become one of the most important welding methods for ferrous metal materials.

3. Features: 1) Low welding cost. Its cost is only 40 50% of submerged arc welding and electrode arc welding.

2) High production efficiency. Its productivity is 1 4 times that of electrode arc welding.

3) Easy to operate. Open arc, no limit to the thickness of the workpiece, can be welded in all positions and can be welded downward.

4) High crack resistance of welds. The weld is low in hydrogen and also has less nitrogen.

5) The deformation after welding is small. The angular deformation is 5 thousandths, and the unevenness is only three thousandths.

6) Small welding spatter. Welding spatter can be reduced when ultra-low carbon alloy or flux-cored wires are used, or AR is added to CO2.

Second, the welding adopts downward vertical welding or upward vertical welding. The former is mainly used for thin sheets, while the latter is used for workpieces with a thickness greater than 6mm.

1. Downward vertical welding.

In order to maintain the weld pool, the welding torch should be pointed diagonally downward towards the weld pool and maintained at the angle shown in Figure 4-20. The arc should always be aligned in front of the melt pool, as shown in Figure 4-21a.

Otherwise, once the molten iron flows to the front of the arc, welding nodules and impenetrable welding will occur, as shown in Figure 4-21b. At this time, the movement of the welding torch should be accelerated, and the forward angle of the welding torch should be increased, and the molten pool metal should be pushed up by the arc force.

Turn left|Turn right.

2.Vertical welding upwards.

The position of the welding torch is very important when welding upwards, as shown in Figure 4-22. The welding torch should be roughly perpendicular to the workpiece. In the case of linear welding, the weld bead is easy to be convex, and the appearance of the weld bead is poor and easy to undercut.

In the case of multi-layer welding, the filler weld bead behind is easy to produce impermeable welding, so it is generally not used, so the upward vertical welding is usually oscillated, and the swing mode is a small oscillation as shown in Figure 4-23a. Because the heat is concentrated at this time, the weld bead is easy to bulge, so in the case of uniform oscillation, it should move upwards quickly.

If a large leg is required, the crescent swing shown in Figure 4-23b should be used to move quickly in the center of the weld bead and stay a little on both sides to prevent undercuts. However, care should be taken not to use a downward curved crescent swing, as shown in Figure 4-23c.

When multi-layer welding, the first layer adopts a small oscillation, while the second layer should adopt the crescent oscillation method as shown in Figure 4-23b. If a large number of welding legs are required, the first layer can also be oscillated in a triangle, as shown in Figure 4-24. At this time, all three points should be stopped, and it should be moved down evenly.

The "inductor" knob on the second welding machine is used:

The first step is to adjust the current knob to the minimum, adjust the voltage knob to the maximum, test welding, do not move the voltage knob at this time, gradually increase the current, and stop it until it can be welded normally;

The second step, in turn, is to adjust the current knob to the maximum first, and then adjust the voltage knob to the minimum, test welding, do not move the current knob, gradually increase the voltage, until it can be welded normally and stop; At this point, you should already feel the action of the current and voltage.

The third step is to minimize the current and voltage knobs, and gradually increase the voltage and current (you need to adjust it repeatedly in the process) until you find a match that you think is the best weld formed, the softest sound, and you can control it. Found a way. The current and voltage corresponding to various welding positions of vertical welding, flat welding, horizontal welding, and vertical welding can be adjusted.

The second shielded welding (full name carbon dioxide gas shielded welding) process is suitable for low-carbon steel and low-alloy high-strength steel various large-scale steel structure engineering welding, its welding productivity is high, the crack resistance is good, the welding deformation is small, the deformation range is large, and the welding of thin plates and medium and heavy plates can be carried out.

Welding materials. 1. CO2 gas purity requirements; The water content does not exceed; The carbon content does not exceed.

2. Copper plating on the surface of the welding wire is not allowed to have rust spots.

The full name of the second shielding welding: metal melting pole carbon dioxide gas shielded welding, that is, the electrode is a meltable welding wire (compared with argon arc welding, the electrode of argon arc welding cannot be melted), and the shielding gas is carbon dioxide gas with oxidizing properties). This is a welding method that uses arc heat to melt filler metal and carbon dioxide to protect the molten pool, which is mainly used for welding carbon steel, and has a higher welding efficiency than electric electrodes due to the wire feeding mechanism.

The second shielded welding is the abbreviation of carbon dioxide gas shielded welding. There are specialized certification bodies.

CO2 gas shielded welding operation.

1 Arc. (1) Keep the dry elongation unchanged.

2) Backward arc striking method, arc striking at the front end of the weld bead 10-20mm.

3) The joint is thinned to prevent the joint from not melting.

2 Arc closing. (1) Keep the dry elongation unchanged.

2) Arc closing at the edge of the melt pool.

Although the arc starting and closing process of CO2 is simple, it is necessary to master the standardized operation process if it meets certain quality requirements.

Arc starting process: Before arcing, press the welding torch switch when maintaining a certain distance between the end of the welding wire and the base metal. During arcing, keep the dry extension length stable.

Due to the low temperature of the workpiece at the arc starting, and the arc cannot be elongated and preheated like manual welding, the backward arc approach method should be used to fully melt the weld bead.

Arc closing process: When CO2 welding arc receiving, the dry elongation length should be kept unchanged, and the burning point should be pulled to the edge of the molten pool to stop the arc, and the welding machine will complete the arc closing process of reburning, ball elimination and delayed gas protection.

3 How to Operate.

1) Left welding method (right left): the residual height is small, the width is large, the spatter is small, it is easy to observe the weld, the welding process is stable, and the gas protection effect is good (non-ferrous metals must use the left welding method), but the depth of dissolution is shallow.

2) Right welding method (left and right): the residual height is large, the width is small, and the spatter is large, which is convenient for observing the molten pool and deep melting.

3) Gun transport method: zigzag swing grab.

4) Flat fillet welding does not swing or swings slightly.

5) Vertical angle upward welding, using triangular gun transport.

6) Welding torch transition: stay on both sides of the molten pool, and transition in 1 3 places before the molten pool.

7) Gun angle: perpendicular to the weld bead, at an angle of 80-90° along the direction of the gun.

8) Test board: gap, the starting point is slightly smaller than the closing point. No blunt edges, reverse deformation 1°.

9) Prevent defects:

Anti-angle non-melt - burn through the included angle. Anti-interlayer non-melting – pay attention to the angle of the gun.