Excessive output power
Because of the limitation of small diameter HFW welded pipe diameter, the section area of magnetic rod will be limited by the internal cutter rod, resulting in low welding speed and excessive output power.
1 The magnetic rods with larger diameters should be chosen as far as possible when space permits;
2 the end of the magnetic rod is aligned with the center of the squeeze roller;
3 The gap between the magnetic bar and the tube is as small as possible, and the control is between 5-15 mm;
4 select a magnetic bar with a high Curie point temperature;
5 using an external magnetic bar;
6 magnetic bar increases the pressure of the cooling water to lower the temperature;
7 Reasonably select the length of the magnetic bar and the number of turns of the induction coil (generally 2 to 5 cycles);
8 Reasonable selection of the opening angle, the smaller the opening angle, the stronger the adjacent effect and the skin effect;
9 Reasonably choose the distance between the induction coil and the center of the squeeze roller (the closer the better), the smaller the gap between the induction coil and the tube, the better, preferably 5 ~ 8 mm;
10 Reasonably choose the frequency of solid high frequency; the cooling water should not be directly poured into the weld; the weld is preferably cooled by inert gas.
Weld seam welding tumor
When producing steel pipe with wall thickness of 6~14 mm, due to low welding speed and slow melting of steel strip section, the sharp edge of the strip edge will melt first and the middle will not melt, resulting in a step temperature. The high-temperature molten metal at the sharp edge of the strip edge flows to the center of the extrusion roller at the end of the magnetic rod to instantaneously produce a weld.
1 Increase the pressure of the cooling rod of the magnetic rod by 1 MPa, and wash away the magnetic rod end welding tumor;
2 add a horizontal compressed air tube to the welding rod at the end of the magnetic rod;
3 The end of the magnetic rod should not be placed in the center of the squeeze roller, and the position should be removed by 20~30 mm;
After the operation of the 4th unit, after the vehicle speed and welding temperature are stable, the shank is raised to start to remove the internal burrs;
5 using semi-melting welding to reduce the production of molten metal slag;
6 using solid-state high frequency and low frequency welding to provide stable frequency and output power;
7 Appropriately increase the opening angle to widen the width of the guiding piece, reduce the melting metal to meet before the center of the pressing roll, so that the strip is close to the pressing roller;
8 Appropriately increase the gap between the magnetic bar and the tube, and keep it at 15-20 mm;
9 Increase the welding speed, reduce metal splash and avoid the formation of welding.
Inner burr ring cutter tipping
The inner burr ring cutter has an optimum working temperature of 650-900 °C, but the inner burr ring cutter tips for various reasons. The following are some common situations.
(1) Over-striped joints are tipped. The welded joint of the strip butt weld will be deformed when it is formed, and a chipping will occur when passing through the squeeze roll.
1 When large diameter pipe passes through the butt welded joint of strip steel, the cutter rod is lowered in time, and then the cutter rod is raised after the butt welded joint of strip steel;
2 For pipes with a small diameter of less than 89mm, the butt welded joint of strip steel must be ground flat to reduce tool collapse.
(2) The edge of the strip is bulged, and the edge of the strip is defective.
1 The edge of the steel strip appears when the drum wall is thin, the molding machine is not adjusted, and the molding machine can be adjusted to eliminate the drum package;
2 The defective part of the strip edge is illegible.
(3) It is easy to tip when producing small diameter pipes smaller than 76mm. Because the small diameter tube is filled with cooling water, the rapid cooling of the weld seam is likely to cause the chipping.
1 Reasonably control the cooling water to avoid rapid cooling of the weld;
2 Add a blowing pipe inside the welding area to isolate the cooling water from the welding zone, increase the flow rate of the cooling water, increase the speed of the machine, and reduce the tipping.
(4) When starting the machine, it is easy to produce a tipping because the knife speed is too fast.
Adjust the pressure reducing valve to take the time within 5s (ie slower starting), the falling time is 2s (ie fast falling knife).
Post time: May-10-2019