The positioning weld can be welded in only one place, located at the 6 o’clock position of the clock, ensuring that the gap there is 2mm. Weld two layers and two passes. The tilt angle of the welding gun and the arc centering position are shown in Figure-Small diameter pipe horizontal rotation butt welding gun tilt angle and arc centering position.
Before welding, place the positioning weld at the 6 o’clock position of the clock, and ensure that the gap at the 0 o’clock position of the clock is 1.5mm.
The arc is ignited at the 0 o’clock position of the clock. The pipe does not move at first and no wire is added. After the groove of the pipe melts and a bright molten pool and molten hole are formed, the pipe starts to rotate and the welding wire is added.
During the welding process, the welding arc is always kept at the 0 o’clock position of the clock, always aligned with the gap, and can swing slightly laterally. The rotation speed of the pipe should be consistent with the welding speed. During the welding process, the filler wire is intermittently fed into the front of the molten pool in the arc in a reciprocating motion, and is added in droplets. The welding wire must be fed regularly and not too fast or too slowly, so as to ensure a beautiful weld. During the welding process, the test tube should be kept at a certain distance from the welding wire and nozzle to prevent the welding wire from disturbing the air flow and touching the tungsten electrode. The end of the welding wire must not leave the argon gas protection zone to prevent the end from being oxidized.
When welding reaches the positioning weld, welding should be suspended. When closing the arc, first pull the welding wire away from the arc area, but do not leave the argon gas protection zone, and at the same time cut off the control switch. At this time, the welding current attenuates and the molten pool shrinks accordingly. When the arc is extinguished, the argon gas is delayed and cut off. The welding gun can be moved away.
After grinding off the tack weld and grinding the closing arc into a slope and cleaning it, the pipe stops rotating and the welding wire is added, and the arc is ignited on the slope. When the weld begins to melt, the wire joint is added, and the welding gun returns to clock 12 The pipe at the point position continues to rotate until the base layer weld is completed.
Before the bottom weld bead is closed, stop feeding the welding wire and rotating it. When the head of the original weld begins to melt, add a wire joint to fill the arc crater and then break the arc.
When welding the cover bead, the other operations are the same as when welding the base layer, except that the lateral swing of the welding gun is slightly larger.
The positioning weld can only be welded in one place, ensuring that the gap there is 2mm, and the gap 180° away from it is 1.5mm. Fix the axis of the pipe in a vertical position, and the side with the smaller gap is on the right. Weld two layers and three passes, and weld the top and bottom layers in two passes.
The tilt angle of the welding gun and the arc centering position are shown in Figure -The tilt angle of the welding gun and the arc centering position for welding the bottom bead.
When welding, strike the arc at the smallest gap on the right side. Do not add welding wire first. After the root of the groove melts to form a molten pool hole, feed the welding wire. When the end of the welding wire melts to form a droplet, gently push the welding wire into the molten pool. Push and swing into the tube to send the molten iron to the root of the groove to ensure the height of the back seam. While filling the welding wire, the welding gun makes a small horizontal swing and moves evenly to the left.
During the welding process, the filler wire is intermittently fed into the front of the molten pool in the arc in a reciprocating motion, and is added in droplets in front of the molten pool. The welding wire must be fed regularly and not too fast or too slowly, so as to ensure a beautiful weld. When the welder wants to move the position to pause welding, he should operate according to the key points of arc closing. When the welder is welding again, he should grind the closing arc of the weld into a slope shape and clean it before welding. Start the arc on the slope and move it to 8~10mm away from the joint. The welding gun should not move. When a bright and clear molten pool is obtained, After that, you can add welding wire and continue welding from right to left.
When welding small diameter pipes with vertically fixed base layers, the heat of the molten pool should be concentrated in the lower part of the groove to prevent the upper groove from overheating, excessive melting of the base metal, and the occurrence of undercuts or a drop in reinforcement on the back of the weld.
The cover layer weld is composed of upper and lower passes. The lower pass is welded first, and then the upper pass is welded. The tilt angle of the welding gun and the arc centering position are shown in Figure-The tilt angle of the welding gun and the arc centering position of the cover layer weld bead.
When welding the lower cover layer bead, align the arc with the lower edge of the base layer weld bead, so that the lower edge of the molten pool exceeds the edge of the pipe groove by 0.5~1.5mm, and the upper edge of the molten pool is 1/2~2/3 of the base layer weld bead. at. When welding the upper cover bead, align the arc with the upper edge of the base layer weld bead, so that the upper edge of the molten chi exceeds the pipe groove by 0.5 ~ 1.5mm, and the lower edge smoothly transitions to the lower weld bead. The welding speed should be appropriately accelerated, and the wire feeding Increase the frequency and appropriately reduce the amount of wire feed to prevent the weld seam from falling.
In order to facilitate welding, when welding small-diameter pipes, divide the pipe weld into left and right half circles according to the clock position. The positioning weld can only be welded in one place, located at the 0 o’clock position of the clock, ensuring that the gap there is 2mm and the gap at 6 o’clock is 1.5 mm or so. Weld two layers and two passes. The tilt angle of the welding gun and the centering position of the arc are as shown in Figure-Welding gun tilt angle and arc centering position for all-position welding of small diameter pipes.
Hold the pipe in a horizontal position with the tack weld at the 0 o’clock position and the end with the smaller gap at the 6 o’clock position. Strike the arc 10mm to the left at the 6 o’clock position of the overhead welding part, and proceed in the counterclockwise direction. When welding the base bead, the positions of the tungsten electrode, nozzle and weld seam must be strictly controlled, that is, the tungsten electrode should be perpendicular to the axis of the pipe, and the distance from the nozzle to the two pipes must be equal. After igniting the arc, the welding gun remains stationary at the arc ignition point. Only when a bright and clear molten pool of a certain size is obtained can the welding wire be filled into the molten pool. The welding wire is fed into the front of the molten pool at an angle of 15° to the tangent line passing through the molten pool. After the welding wire is sent to the molten pool along the top of the groove, the welding wire should be gently pushed into the molten pool and swung into the pipe, thereby improving the welding quality. The height of the back side of the seam should be adjusted to avoid pits and incomplete penetration. While filling the wire, the welding gun should move counterclockwise at a constant speed.
During the welding process, the moving speed of the filler wire and the welding gun must be uniform to ensure a beautiful weld.
When welding reaches the 0 o’clock position of the clock, welding should be stopped temporarily. When closing the arc, first pull the welding wire away from the arc area, but do not leave the protected area, and then cut off the control switch. At this time, the welding current gradually decays, and the molten pool also decreases accordingly. When the arc is extinguished, the argon gas is cut off after a delay. The welding gun can be moved away.
After welding one side of the horizontally fixed small-diameter pipe, the welder moves to the other side of the pipe. Before welding, the positioning weld should be removed first, and the arc closing point (0 o’clock position) and arc starting point (6 o’clock position) should be ground into a slope shape and cleaned, and then the arc closing position (0 o’clock position) and arc starting position (6 o’clock position) should be ground into a slope shape, and then the 6 o’clock slope should be Move the arc to the left side 8~10mm away from the joint. Keep the welding gun still. When a bright and clear molten pool is obtained, add the welding wire and weld clockwise to 0 o’clock. Connect the last joint and finish welding the bottom layer. road.
When welding the surface bead of the cover, except that the lateral swing of the welding gun is slightly larger and the welding speed is slightly slower, the rest is the same as when welding the bottom bead.
This position is more difficult to weld than horizontal fixed small diameter pipe butt joints. In addition to mastering the horizontally fixed small-diameter pipe welding technology, welders must also move horizontally with the position of the welding pool when welding the inclination angle of the welding gun, the wire adding position and the arc position.
In order to facilitate welding, the pipe weld is divided into left and right half circles according to the clock position during welding. The positioning welds are evenly distributed in three places, located at the 7 o’clock position, ensuring that the gap is 3mm at the 6 o’clock position and 4mm at the 0 o’clock position. The axis of the pipe and the horizontal plane are fixed at an angle of 45°.
The inclination angle of the welding gun, the wire adding position and the arc centering position for welding the bottom bead and cover bead are shown in Figure 5-47. Note: During the welding process, in addition to maintaining the same relative relationship, the inclination angle of the welding gun, wire adding position, and arc centering position must also move horizontally following the centerline of the groove. The welding steps and requirements are the same as those for butt welding of horizontally fixed small diameter pipes.
15+ Years Industry Practice Experience. JINAN APES is one leading exporter and manufacturer in the field of welding machines.
