DE2343885A1 - Construction element of two connected tubes of different matls. - by welding, cutting, deforming and finishing tubular workpieces - Google Patents

Abstract

A construction element is made by explosively welding together two tubes of different metals, (the thickness of the metal tubes being related to their elastic moduli) and then dividing the pipes into composite rings which are deformed to obtain parallelogram cross-section are finished by a swarf removing operation. Construction elements for aircraft and spacecraft made e.g. of titanium alloy and steel.

Description

Fraunhofer Society 2343885

to promote applied

Forsohung e.V., based in Munich,

8 Münohen 19, Leonrodstr. 54 72/7322

Construction element for connecting two pipes of different materials Ξ ** Α Verfa hrenz u se i n it creation H

The invention "relates to a structural element for connection two pipes made of different materials and a method for its economical production.

In the aerospace industry "there is a need to Create constructions with low weight. That is why high-strength materials are used. your connection often causes difficulties. Fusion welding process are often not possible at all or often reduce the strength of the base material in the heat-affected Zone down. Robust and riveted connections have a high notch effect and thus reduce fatigue strength erheblioh.

In many cases the connections must be made from different metals such as litan and Stole. In the fusion welding process, brittle intermetallics are created in the weld seam Phases, so that these are completely different as a joining technique, unless remedial action is taken through suitable intermediate layers kaia η.

In particular, there are usually the following requirements for connections, which the known methods at least ζ.ΐ. do not do justice:

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1. The connection must have a steady transition in stiffness.

2. With small wall diagrams and large component dimensions high strength is required.

3. The notch effect should be low and thus the permanent f be great.

4. The outer, in many cases also the inner contour, should be smooth.

5. The connection should be economically feasible.

In the following, a construction element and a method for efficient production is described that the identified deficiencies are eliminated and the stated requirements are met. The construction element can E.g. through electron beam welding between two ! rush to be welded. It is used to connect cylindrical or elliptical constructions.

According to the invention, the construction element is designed so that the metals I and II are explosivversohweißt in the transition part III in a stocked version and that the dioks d-j- and djj of metals I and II preferably behave like their moduli of elasticity Ej to Ejj.

The starting point of the process is explosive welding, which is known in its basics. That's how it is Use of explosive welding to clad large steel plates with corrosion-resistant metals known for chemical apparatus engineering. For the same purpose, pipes with corrosion-resistant metals can also be used on the outer and / or inner surface with e.g.

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be provided with a! Ditan coating. Also are procedures ■ known to perform explosive welding of pipes (possibly for pipelines) to connect with each other.

In the case of load-bearing structures, the following is a method for producing a connecting element E.g. between the two metals steel (high strength) and the titanium alloy! DiAlV 64 (also high strength), which allows several parts to be produced in one operation.

First of all the construction element itself:

Fig. 1 shows its cross section again. In order to be able to meet the requirements outlined at the beginning, the welding is carried out in a jointed design. The requirement of a constant transition of the stiffness from one metal to another is achieved according to the invention by the fact that the thicknesses dj and d ^ j of the different metals I and II, explosively welded in the transitional part III, behave _{like their moduli of elasticity E 1} and E ₁₁ .
The manufacture can be done in different ways.

The starting point for the production of such an element is an inside or outside clad tube like Duroh Explosive plating is manufacturable and commercially available. Rings are peeled off the tube. The Rings are deformed into conical rings. The shaping can preferably be done by explosive deformation or with the help of a press. The construction element is turned out of the conical ring by machining.

Fig. 2 shows thematically the individual steps a) through d) again, a) shows a clad tube that is in b) is divided into rings, from which naoh o) conical rings are formed, from which in turn naoh d) construction

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elements are rotated as they are in Pig. 1 are shown on an enlarged scale.

According to a modified method, the starting point is again a clad pipe, as in Pig. 3, a). The tube is explosively formed into a tube with axial fluctuations in diameter (Zick-Zaok, see Pig. 3, b). Then the pig taper rings are removed. 3, ο).

In contrast to the procedures outlined, a Simplification can be made in such a way that the reshaping and demounting are carried out in one step will. A die with a sawtooth tooth is used for this purpose Porm (Pig. 4). It should also be noted that instead of water as the transmission medium and one in the center arranged rod-shaped explosive charge (Pig. 4) auoh with a directly on the inside of the tube in a suitable Layer thickness applied explosive charge can be worked.

To remove the conical rings, the Porm must either be divided axially once or several times in the transverse plane.

A further simplification of the process consists in the fact that all processes, namely those of plating, of forming and the Irennens combined in one process will. This is done in Pig. 5 arrangement shown. The explosives are directly on the inside of the in a distance to the outer tube attached inner tube attached. To remove the tapered rings must also here the porm (die) can be divided either once in the longitudinal direction or several times in transverse planes perpendicular to it. To avoid welding the conical rings with the Porm, the latter is covered with a thin ceramic compound to coat.

Another method only includes plating and the reshaping. Purely this procedure results in the one in Pig. 6 reproduced arrangement.

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Claims (6)

Fraunhofer Society ** for the Promotion of Applied Research e.V., Munich headquarters, Münohen 18, Leonrodstr. 54 72/7322 claims 1. Construction element for connecting two pipes made of different materials, characterized, that the metals I and II are explosively welded in the jointed design in the transition part III and that the thicknesses dj and djj of the metals I and II are preferably related to their moduli of elasticity E ₁ to E ₁₁ . 2. A method for producing the device according to Claim 1, characterized, that rings are first cut from an explosive clad tube and then deformed into conical rings and finally brought into the final shape by machining. 3. Method of manufacturing the device naoh the Claims 1 and 2 marked daduroh, that the tube initially to such a ziokzag form occurring in the axial Riohtung linear durometer fluctuations is formed, from which tapered rings are machined and turned. -2- 509812/0469 4. Method according to claim 3 »
characterized, that the reshaping and the removal in one step is carried out by means of a sawtooth-shaped, divisible die or male die. 5. Method according to claim 3,
characterized, that the plating of the tube, the forming and running into conical rings in one operation the way that the explosives are made on the inside (outside) of the spaced to the outer (inner) pipe attached inner (outer) pipe is attached, while inside in turn a sawtooth-shaped split die (male die) is arranged. 6. The method according to claims 4 and 5, characterized in that that the die is coated with a thin ceramic compound. 509812/0469 Le e rs e ite