HF (Excessive-Frequency) welding is a really efficient high-speed welding course of used extensively in metallic tube and pipe manufacturing. Whereas it’s effectively suited to excessive quantity, large-to-small diameter variations of primarily thicker walled tubing, it’s nonetheless a course of with a lot of variations that every one need to be managed correctly for the absolute best welding course of to happen.
As the 2 strip edges come collectively and transfer by means of the induction coil previous to welding, measuring the temperature within the neighborhood of the “V” can present fabricators with a wealth of details about how effectively the tube is being shaped and the precision and general stability of the welding course of.
For instance, measuring the temperature profile alongside every strip edge (A, proven under) of the tube main as much as the Apex can present a sign of how effectively every strip edge is heating as much as the purpose of becoming a member of.
Fig. 1: The “V” on an HF Tube Mill and its Associated Options (Xiris)
Heating up the tube too shortly or too gradually might create potential weld defects comparable to freeze line, sunken welds or trigger extra materials to be squeezed out throughout welding. Measuring the temperature profile throughout the tube (B) from one strip edge to a different can decide instantaneous heating ranges after the tube passes by means of the weld coil.
Evaluation of those temperature profiles can indicate how constant each strip edges are being warmthed.
Temperature differentials from one strip edge to the opposite might be brought on by impeder points or the way in which the working HF inductor coil was arrange. Monitoring these temperatures might be helpful to point out potential welding defects comparable to mismatch or undercut.
As soon as the tube strip edges come collectively, measuring the temperature cooling fee from the Apex to the SqueezePoint alongside the Weld Size (C) can be fairly helpful.
On this area, there isn’t a additional heating that happens as a result of there isn’t a inductive present flowing, so the warmth dissipates quickly due to the excessive temperature gradient between the strip edges and the remainder of the tube. If the tube weld cools too shortly on this zone, the weld could not type correctly when stress from the rollers is utilized.
Measuring numerous spot temperatures after the Apex will also be helpful. By detecting and measuring the weld scorching spot, or the utmost temperature on the weld bead after the Apex (D), fabricators can get an instantaneous indication of how constant the heating of the strip edges is previous to welding.
Typically, the utmost temperature level might be noticed transferring ahead and aft because the stress modifications on the weld seam throughout common tube manufacturing.
Trying on the temperature profile throughout the tube close to the squeeze rollers (E) can point out the place the height temperature is situated throughout the weld. The height temperature normally happens on the middle of the weld bead.
Nevertheless, its precise location can point out if the weld seam is transferring in any respect on account of tube twisting (tube rolling). As well as, the height temperature at this level may point out the well being of the weld by measuring the completed weld bead temperature at some extent simply after the weld bead has been
Determine 2: Fig 2: Thermal Picture Exhibiting V-Angle, Apex, Scorching Spot and Different “V” Options with Beneficial Temperature Measurement Factors (Xiris)
Implementing a thermal measurement system on a tube mill can present new types of info that may be of nice use to the producer. Xiris has developed the Pre-Weld HF Inspection system utilizing a SWIR thermal digital camera in a sturdy housing that is ready to stand up to the cruel surroundings within the neighborhood of the weld head. Utilizing such a instrument will permit fabricators to amass thermal knowledge that may assist them higher management their welding course of main to higher high quality welds.