Friends all welcome. To our weld joint has turned out as expected, smoothly and without displacement of welded parts, we need to put in front of the main welding tack welding. And today we discuss this topic, and why it is so important in tack welding.
Generally what is tack-welding is a short weld to 20 mm or welded point which serves for rigid fixation of the welded components. Subsequently tack fused with the main seam, so it is necessary to do a height and a width of 0.5-0.7 main seam. And now let's look at the examples of the importance of tack welding.
In this example, I will use the strip 40 of plate, cut to 50mm. Grab and we welded to the bottom sheet metal piece 3mm thick.
To begin, we have done wrong, I picked up on the left to the bottom plate with one hand, and on the right welded one side completely without tack. Let's see what kind of defect in this case is impossible.
Opposing edges of the plates in both our cases away from the base plane, forming a gap. This is a good example of the small details, but let's imagine that in their place will be more volumetric and overall things only then will a big problem that needs to be corrected, and to avoid this it is better to do it right.
Why did it happen? When we did, or tack weld then this point molten metal began to rapidly cool and This greatly reduced in volume, so we have the opposite edge of the plate began to rise from base. Always remember it-stitch or tack cools, while reducing in volume and thereby causing mechanical force in the binding details. And how to put a tack? Let's investigate.
Tack you need to put on the diagonals of the plate, but not on most angles, and moving away from them by 5-10 millimeters, so that later they are welded to the main seam. And yet, when we catch small parts, as in our example, after the first tack to keep the item pressed fingers in the base-Kragh, hammer, etc., until such time until put the second, and after a pair of second hold seconds.
We see that correctly taking a plate, it fits snugly without gaps to the ground. Now you can make the main welding, starting from any edge of the plate, but starting from a place where no tack and moving to the most tack at the end of the seam it is fused. Here is an example with small details, enough for two tacks on diagonals, but with bigger better bet more tack-4 and more, all on the situation.
When welding larger components need to use all sorts of devices for rigid fixing-clamps, homemade prizhimuhi crocodiles, karkalygi and so on. After fixing and tacking stamped and welded parts.