DE661009C - Process for electrical resistance welding of the longitudinal edges of thick-walled hollow bodies - Google Patents

Description

£ Q

ISSUED AIW
June 9, 1938

It is known that in the production of thin-walled hollow bodies from sheet metal, the sheet metal edges, blunt, as shown in Fig. 1, or with insert material, as shown in Fig. 2, to be welded together by electrical resistance welding. These expire however, have the following disadvantage:

As is well known, the low-voltage welding current has the tendency to take the shortest path and therefore runs for the most part in the aforementioned form in resistance welding near the edge of the sheet, i.e. in the upper sheet phase. The consequence of this is that the part less traversed by the StiOm, ie the lower blank phase, is not sufficiently heated and is therefore also imperfectly welded. If one tries to counteract this problem by also attaching electrodes to the lower phase of the sheet, on both sides of the sheet metal edges to be welded, an even amount of current flows in the upper and lower sheet phases; however, the middle sheet metal phase is not sufficiently passed through by the welding current and is consequently heated to a lesser extent. The consequence of this disadvantage of the previously known resistance welding for welding hollow bodies is therefore that they can only be used up to a certain sheet metal thickness, up to about 5 mm. can be applied.

It has also become known for the production of circumferential seams, overlaps to be used that are designed so that the parting line is mainly horizontal or is inclined. However, this arrangement cannot be used for longitudinal seams of thick-walled hollow bodies because the the production of these welded joints used pressure electrodes in the below Their kneading action would weaken the seams.

According to the invention, the disadvantages of the known methods are eliminated and Connections are formed which allow the use of resistance welding for longitudinal seams even with considerable wall thicknesses enable in an impeccable manner. For this purpose, the edges of the to be welded Sheets in such a way, and expediently by planing with cutting tools, formed that a Parting line arises, the main part of which runs horizontally or with a slight incline and at the ends of which there are vertically or steeply extending approaches. Included the wall thicknesses remaining after planing are chosen so that the total 6 < > The thickness of the sheet at the joint is greater than the wall thickness of the Sheet, but still remains significantly behind twice the wall thickness of the sheet.

* i The Palenlsncher has given as the inventor:

Dr.-lng. Karl ll'a / hiiann in Düsseldorf.

Claims (1)

COl In this way it is possible to have an even To achieve distribution of Slromverkiufs and at the same time under the Influence of the pressure action of the electrodes in progress kneading process as much material to have available that after the end of Schwcißung the wall thickness of the The weld seam is essentially the same as that of the sheet metal. During the weld itself ίο the abutting metal sheets have a good grip, as they are not facing each other can move, but held by the steep parts of the joint will. The finishing of the edges also has the advantage of great simplicity and is in particular much more advantageous than flanging a long sheet metal edge, as it would be necessary if the ends of the sheets in a known manner to Formation of twice the wall thickness would have to be superimposed. aside from that would be the welding point when using such a method on thick sheet metal get such a strength that a very large pressing pressure and considerable heating work would be necessary to press them down to the thickness of the simple sheet metal. Figs. 3 to 6 illustrate different 3u dene embodiments of the invention, and although show Fig. 3 and 4 two different views of an example and the Fig. 5 and 6 other types of sheet metal. edging. After the two electrode rollers have been placed in place, the overlapped sheet metal edges are heated uniformly over the entire surface to be welded and, even after the welding temperature has been reached, they are welded by pressure from the electrode rollers. As the wall thickness increases, the resistance to the welding current is increased overall; However, there is no pre-welded joint that experiences an increasing preference for the passage of current with increasing wall thickness, as is clearly visible in the above-mentioned methods (cf. Figs. 1 and 2). With the new method, the current runs through the overlap to be welded, completely uniformly and in a straight line, and there is no longer a preferred path for the current to pass through. The space between the Sioükanteii α and /; is filled and welded by the liquid metal which is pressed out at the point of overlap by the pressure of the electrode rollers protruding laterally beyond the overlap. The overlap is done like this. So that the thickness of the same is greater than the thickness of the wall, but much less than twice the sheet metal thickness, so that there is enough material for an intimate welding and for filling the spaces 6g at the abutting edges. With very large wall thicknesses and large cavities between the abutting edges these are filled in by means of electric arc welding and additional material. the tensile forces in the wall of the high-quality on the finished hollow body overlapped resistance weld should be included while the arc weld is primarily used for filling. The electrode rolls can protrude laterally over the overlap, so that after Compression of the overlap to sheet metal thickness, the protruding part of the electrode rollers touches the sheet metal wall on the side of the abutting edges and causes heating and any welding material pressed out between the abutting edges onto the Wall thickness of the hollow body is printed flat. 'Ί'λτ KN τA.xsi'κ im π: A method for electric Widerstaiulsschweißung of the longitudinal edges of thick-walled yo hollow body, such as boiler drum, in which the edges are joined with an overlap, characterized in that, in the overlap, a parting line is formed, the horizontal its main part in ^l J5 or low skew and at the ends perpendicular or steep, and that the overlap is given a thickness before welding, which is greater than that of the sheet, but significantly less than twice the normal thickness. 1 sheet of drawings number in ηκιι μκ π; |) Μί: κκκη