DE2454457B1

DE2454457B1 - Brazed joint using grooves on a mating surface - esp. for assembling turbine blades on rotors

Info

Publication number: DE2454457B1
Application number: DE2454457A
Authority: DE
Inventors: Karl Fetzer
Original assignee: Voith Getriebe KG
Current assignee: Voith Getriebe KG
Priority date: 1974-11-16
Filing date: 1974-11-16
Publication date: 1975-06-19

Abstract

The joint is made using a flux and a brazing temp. of 610-710 degrees C., where the two parts have a large joint surface and a prescribed gap width of 0.05-0.2mm. The novelty is that at least one of the parts is provided with grooves on its joint face, the grooves possessing sides which are perpendicular to the joint face and having a min. width (b) of 0.6mm and min. depth (a) of 0.4mm. The pref. dimensions are (a) 0.5-0.7mm; and (b) 0.8-1.0mm and the end face of one component may be recessed to provide the gap-width of 0.05-2mm. This process is esp. for brazing drawn or precision-cast turbine blades onto rotors.

Description

Der Erfinder beschreitet demgegenüber einen anderen Weg, indem er durch eine ausreichende Bemessung der erfindungsgemäß vorgesehenen Rillen dafür sorgt, daß sich diese nicht völlig mit Lot füllen, sondern daß dort das Lot zusätzliche Hohlkehlen-Lötnähte bildet und daß sich der verbleibende Rest der Rillen mit Flußmittel füllen kann. Es kommt also wesentlich darauf an, daß die Seitenwände der Rillen wenigstens angenähert senkrecht zur Lötfläche angeordnet sind. Hierdurch und durch die im Anspruch 1 angegebenen Mindestabmessungen unterscheiden sich die Rillen grundsätzlich von den Rillen der bekannten Lötverbindung gemäß dem Buch von L ü d e r. Dort unterliegen nämlich die Rillen infolge ihrer sehr kleinen Querschnittsabmessungen der Kapillarwirkung und sind somit stets völlig mit Lot ausgefüllt. Sie sind dadurch nicht in der Lage, Hohlkehlen-Lötnähte zu bilden und etwa vorhandenem Flußmittel, das nicht mehr nach außen entweichen kann, Platz zu bieten. In contrast, the inventor takes a different approach by by adequately dimensioning the grooves provided according to the invention for this purpose ensures that this is not completely filled with solder, but that there is additional solder Fillet welded seams are formed and the remainder of the grooves is covered with flux can fill. So it is essential that the side walls of the grooves are arranged at least approximately perpendicular to the soldering surface. Through this and the minimum dimensions specified in claim 1 differ Grooves basically from the grooves of the known solder joint according to the book of Lü d e r. There the grooves are subject to their very small cross-sectional dimensions the capillary action and are therefore always completely filled with solder. You are through it unable to form fillet soldered seams and any flux present, that can no longer escape to the outside, to offer space.

Im Ergebnis bietet somit die Erfindung den Vorteil, daß der Füllungsgrad des Lötspaltes mit Lot beträchtlich erhöht wird oder daß jedenfalls mit größerer Sicherheit ein hoher Füllungsgrad erreicht wird, und zwar ohne besonderes Zutun der ausführenden Person; d. h., die Lötverbindung kann auch serienmäßig in weitgehend selbsttätig arbeitenden Lötvorrichtungen hergestellt werden. Einerseits durch den höheren Füllungsgrad im Lötspalt und andererseits durch die zusätzlich gebildeten Hohlkehlen-Lötnähte wird eine beträchtliche Steigerung der Festigkeit der Lötverbindung, insbesondere der Biegewechselfestigkeit, erreicht. As a result, the invention offers the advantage that the degree of filling of the soldering gap is considerably increased with solder, or at least with a larger one Safety a high degree of filling is achieved, without any special action the person carrying out the work; d. This means that the soldered connection can also be largely produced as standard automatic soldering devices are produced. On the one hand through the higher degree of filling in the soldering gap and, on the other hand, by the additionally formed Fillet soldered seams will significantly increase the strength of the soldered joint, especially the flexural fatigue strength.

Das günstige Ergebnis wird offensichtlich auch dadurch erzielt, daß sich das flüssige Lot entlang der inneren (von den Rillen gebildeten) Hohlkehlen genau so rasch ausbreitet wie entlang der äußeren Hohlkehlen, und daß somit zumindest ein Teil des Flußmittels rascher aus dem Lötspalt verdrängt wird als beim Nichtvorhandensein von Rillen, oder bei der Verwendung von Rillen mit der aus dem Buch von L ü d e r bekannten Querschnittsform und -größe. Mit anderen Worten: Durch die Erfindung wird dafür gesorgt, daß bis zur vollständigen Ausbreitung von flüssigem Lot entlang der äußeren Hohlkehle, solange also ein Ausgang für entweichendes Flußmittel offensteht, eine größere Teilmenge des Flußmittels aus dem Lötspalt verdrängt wird. The favorable result is obviously also achieved in that the liquid solder along the inner fillets (formed by the grooves) spreads just as quickly as along the outer flutes, and that at least a part of the flux is displaced from the soldering gap more quickly than in the absence of it of grooves, or when using grooves with the one from the book by Lü d e r known cross-sectional shape and size. In other words: through the invention It is ensured that until the complete spread of liquid solder along the outer groove, as long as an exit for escaping flux is open, a larger portion of the flux is displaced from the soldering gap.

Im Anspruch 2 sind Querschnittsabmessungen für die Rillen angegeben, die sich bei Versuchen als besonders günstig erwiesen haben. Durch die Ausbildung der Lötfläche des einen Bauteiles gemäß Anspruch 3 wird das genaue Positionieren der Bauteile zueinander erleichtert. Man wird hierbei zweckmäßig das eine Bauteil vor dem eigentlichen Lötvorgang auf das andere Bauteil aufsetzen, gegebenenfalls unter Einsatz einer die genaue Lage des einen Bauteils bestimmenden Hilfseinrichtung. Durch das Vorsehen der »am anderen Bauteil anliegenden Flächenteile« erübrigt sich einerseits eine Halteeinrichtung zum Einstellen der geforderten Lötspaltweite. Andererseits kann auch auf ein gegenseiti- ges Anpressen der beiden Bauteile verzichtet werden, so daß flüssiges Lot auch in den Teil des Lötspaltes eindringen kann, in dem die beiden Bauteile aneinander anliegen. In claim 2 cross-sectional dimensions for the grooves are given, which have proven to be particularly favorable in tests. Through training the soldering surface of a component according to claim 3 is the exact positioning of the components to each other. One component is expediently used here Put it on the other component before the actual soldering process, if necessary using an auxiliary device that determines the exact position of a component. The provision of the "surface parts resting on the other component" is unnecessary on the one hand a holding device for setting the required soldering gap width. on the other hand can also rely on a mutual there is no need to press the two components, so that liquid solder can penetrate into the part of the soldering gap in which the both components are in contact with each other.

Ein Ausführungsbeispiel der Erfindung ist nachfolgend an Hand der Zeichnung erläutert. Darin zeigt F i g. 1 einen Längsschnitt durch ein Turbinenschaufelrad eines hydrodynamischen Drehmomentwandlers, Fig.2 eine Ansicht auf die Stirnflächen zweier Schaufeln des Schaufelrades in Richtung der Pfeile II-II der Fig. 1, F i g. 3 einen stark vergrößerten Querschnitt durch die Lötverbindung zwischen einer Schaufel und dem Schaufelkörper nach Linie III-III der F i g. 2, F i g. 4 eine Ansicht auf eine der Schaufeln in Richtung des Pfeiles IV der F i g. 2 im Zustand vor dem Lötvorgang. An embodiment of the invention is shown below with reference to the Drawing explained. In it, F i g. 1 shows a longitudinal section through a turbine blade wheel of a hydrodynamic torque converter, FIG. 2 a view of the end faces two blades of the impeller in the direction of arrows II-II of FIG. 1, F i G. 3 shows a greatly enlarged cross section through the soldered connection between a Blade and the blade body according to line III-III of FIG. 2, fig. 4 is a view onto one of the blades in the direction of arrow IV in FIG. 2 in the state before Soldering process.

Das in der Zeichnung dargestellte Turbinenschaufelrad umfaßt einen Schaufelradkörper 10 mit einer Nabe 11, mehrere aus gezogenem Profilmaterial hergestellte Schaufeln 12 und eine Deckscheibe 13. Die Schaufeln 12 sind durch Hartlöten unter Verwendung eines Flußmittels bei einer Löttemperatur zwischen 610 und 7100C mit dem Radkörper 10 einerseits und der Deckscheibe 13 andererseits verbunden. The turbine blade wheel shown in the drawing comprises a Impeller body 10 with a hub 11, several made of drawn profile material Blades 12 and a cover plate 13. The blades 12 are brazed below Use of a flux at a soldering temperature between 610 and 7100C the wheel body 10 on the one hand and the cover plate 13 on the other hand.

In F i g. 3 ist ein Lötspalt zwischen einer der Schaufeln 12 und dem Radkörper 10 mit 20 bezeichnet; seine Spaltweite s beträgt 0,05 bis 0,1 mm. Diese Spaltweite wird dadurch genau eingehalten, daß in jeder Schaufelstirnseite an jedem Schaufelende eine Erhebung 21, 22 von der Höhe der Spaltweite vorgesehen ist (F i g. 4). In Fig. 3 is a soldering gap between one of the blades 12 and 12 the wheel body 10 denoted by 20; its gap width s is 0.05 to 0.1 mm. This gap width is precisely adhered to in that in each blade face an elevation 21, 22 at the height of the gap width is provided at each blade end is (Fig. 4).

Diese Erhebungen bilden somit direkt am Radkörper 10 bzw. an der Deckscheibe 13 anliegende Flächenteile der Lötfläche der Schaufel 12, während der übrige Teil 23 der Lötfläche sich in einem Abstand der genannten Spaltweite s vom Radkörper bzw. der Deckscheibe befindet. Dieser Abstand ist in F i g. 4 übertrieben groß dargestellt.These elevations thus form directly on the wheel body 10 or on the cover disk 13 adjacent surface parts of the soldering surface of the blade 12, while the remaining part 23 of the soldering surface is at a distance of the mentioned gap width s from the wheel body or the cover plate is located. This distance is shown in FIG. 4 shown exaggerated.

Die Lötflächen jeder Schaufel weisen einige längsgerichtete Rillen 25 auf, deren Seitenwände 26 senkrecht zur Lötfläche stehen. Die Tiefe a dieser Rillen beträgt 0,5 bis 0,7 mm und die Breite b 0,8 bis 1,0 mm. The soldering surfaces of each blade have some longitudinal grooves 25, the side walls 26 of which are perpendicular to the soldering surface. The depth of this Grooves is 0.5 to 0.7 mm and the width b is 0.8 to 1.0 mm.

Wie aus F i g. 3 ersichtlich, bildet das gestrichelt schraffierte Lot die üblichen äußeren Hohlkehlen-Lotnähte 30 und gemäß der Erfindung zusätzlich in jeder Rille 25 zwei innere Hohlkehlen-Lotnähte 31, die je nach der Rillenbreite b in der Mitte der Rille mehr oder weniger ineinanderlaufen. Soweit die Rillen 25 nicht vom Lot ausgefüllt sind, kann sich darin mehr oder weniger das im Lötspalt verbleibende Flußmittel 32 ansammeln. As shown in FIG. 3 can be seen, forms the hatched dashed line Solder the usual outer fillet solder seams 30 and additionally according to the invention in each groove 25 two inner fillet solder seams 31, depending on the groove width b run into each other more or less in the middle of the groove. As far as the grooves 25 are not filled by the solder, there can be more or less that in the soldering gap accumulate remaining flux 32.

Claims

Claims: 1. Brazed and using a flux connection between two components made at soldering temperatures of 610 to 7100C, which have a large soldering gap between them with a definable gap width (S = 0.05 to 0.2 mm), with the solder both at least parts of the soldering gap as also fills the fillets formed by the two components, marked thereby e t that the soldering surface forming the soldering gap (20) of at least one component (12) Grooves (25 #) with side surfaces at least approximately perpendicular to the soldering surface (26), the minimum depth (a) of the grooves (25) 0.4 mm and the minimum width (b) is 0.6 mm.

2. solder connection according to claim 1, characterized in that the The depth (a) of the grooves (25) is 0.5 to 0.7 mm and the width (b) is 0.8 to 1.0 mm.

3. Soldered connection according to claim 1 or 2, characterized in that that the soldering surface of one component (12) is divided into directly on the other component (10, 13) adjacent surface parts (21, 22) and in such surface parts (23) which from the other component at a distance (s) equal to the size of the specified soldering gap are located.

4. Impeller for a turbomachine, its individual blades are made of drawn profile material or by precision casting, characterized in that that the connection between the blades (12) and the wheel body (10, 13) according to one of claims 1 to 3 is formed.

From the VDI reports, Vol. 9, 1956, pp. 79 to 82, it is known a brazed connection between two components using a flux at soldering temperatures between 610 and 7100C, whereby the components have a Form a large solder gap (a butt joint or an overlap gap) of definable Size, namely between 0.05 and 0.2 mm. The two components have a common soldering gap is always bounded by a fillet formed by both components. It is known (Fig. 9 of the cited publication) that the liquid solder spreads faster along the fillet than within the soldering gap. The finished soldered connection therefore usually has a well-formed soldered seam along it the fillet, while the inside of the soldering gap often only to a small extent is filled by solder and on the other part of residual flux, which is no longer could escape from the soldering gap. But now there is the strength of a soldered joint crucially depends on what proportion of the solder gap area is fulfilled by the solder. The high strength of a soldered joint is particularly important, e.g. B. in a highly stressed Impeller of a turbomachine, the blades of which are soldered to the impeller body are connected.

In order to achieve high-strength soldered connections, it is made of the above Document also known to solder large-area soldering gaps from the inside out, d. H. create a »solder depot« inside the soldering gap; this solder depot owns the Shape of a wire or sheet metal section, the thickness of which is greater than that of the soldering gap is. During the soldering process, the components are then pressed together so that the liquid Solder can drive the flux in front of it and the components eventually into their final position to get to each other. However, this method cannot then be used if it, such as B. with the said paddle wheel, on an exact positioning of the two components to each other. In such a paddle wheel are namely the blades to be soldered in a certain cross-sectional shape, which is required by the Flow deflection is set, already finally completed, z. B. by By casting or by drawing, and it is now a matter of soldering a predetermined one Position of the blade on the impeller body, in particular also while maintaining a given tolerance of the distance between the various blades, if possible to achieve exactly.

It is also known (Lüder, "Handbuch der Löttechnik", Verlag Technik Berlin 1952, 5. 306 to 315), for components that were riveted before soldering or connected to one another by a press fit, with an optimal soldering gap between 0.05 and 0.2 mm is not adjustable, in the soldering surface of one of the two Components have to be worked in with a fine groove, which makes it easier for the solder to flow in shall be. The grooves have a triangular cross-section with a depth of 0.2 mm and 0.3 mm of greatest width (Fig. 335). Otherwise it is a soldering process »With copper as solder, dispensing with any flux«; # the soldering process takes place instead of under protective gas in a continuous furnace at about 11200 C, so that this known method for components made of such steels that are exposed to temperatures above 7500C Suffer a decrease in strength, is not applicable.

The present invention therefore proceeds from one with ## flux and at soldering temperatures of only 610 to 7100C, where the parts to be connected have a soldering gap of a definable size (0.05 to 0.2 mm) form. The invention is based on the object of such a soldered connection to improve that the soldering gap with security to the largest possible part of Lot is fulfilled.

This task is accomplished through the application of the distinguishing features of claim 1 solved. The invention is based on the recognition that the disadvantage the well-known soldered connections (VDI reports), according to which the soldering gap usually only closes an insufficient part is filled with solder, the result is that the part of the Flux that could no longer escape from the soldering gap, inevitably Solder blocks access to the soldering gap. It is true with so-called blind hole soldering known to install an "emergency exit" for the flux, provided this is in terms of strength is permissible. However, this requires additional manufacturing costs for manufacture suitable channels for this purpose. There is also the risk that some of the liquid Solder escapes through the "emergency exit" and that means there is no solder in the coves Sufficient solder seams are formed; # these fillet solder seams are a prerequisite for good fatigue strength of the soldered joint.