DE2118848C3 - Rotationally symmetric, hollow composite body and process for its manufacture - Google Patents

Description

b) Are layer consists of a fiber material, in particular made of tungsten, beryllium, steel, boron, carbon or silicon carbide fibers, as wound continuous fibers, as staple fibers or as fiber mats are arranged, the joints between the individual fibers with one of the below (a) said metals are cast, c) the coefficient of thermal expansion of the pure Metal of the inner layer, st equal to or greater than that of the Matr.xmetalls the fiber reinforced outer layer.

2. A method for producing a rotationally symmetrical composite body according to claim 1 by centrifugal casting, wherein the metal to be cast with the help of a rotating or stationary, lying in the axis of a rotating mold casting device on the Kok. Endless fibers, staple fibers or fiber mats lying on the inner wall is poured and then a second layer is applied to the fiber-reinforced layer impregnated with the Matnxmetall. Layer of a metal is poured on, which has an equal or greater thermal expansion coefficient than the Matnxmetall be-SS, characterized in that the rotation ₊ o of the mold is maintained until the metal of the inner layer has solidified.

material

g £} "_ium> Boron, Koh as a fiber material _{Ver ^ matrix} metals on Nik-

Serve VTtan or aluminum base

I ₉₇₀ , 20, pp. 1390 to 1392).

^ "its fiber-reinforced material

As a result, there is a _load in fiber

high _{strength in} fiber direction

^ ί / _Γ ^ the strength values of its Matnxma _ter ials' and with tensile load perpendicular to the fiber

_{ih einma} , this achieved, ^w " ^e ™ ^ * ⁰ ^ material tager ^ lit W ^

The necessary alternating voltages

_take n., _u " _{WVSrner mii} , _m

_{A beautiful} nell rotating hollow body "" _{fibers in} tangentialerR.chtung run urn d, _Fliehkrafl resuH ^ Governing Jangentialen _def train _nts record, it act as ^"e ™ _T ^P _ransver ^B _sa i _sc hwingungen <ff ^e ^. perpendicular to the grain; of this is the

_Necessary to meet the rabbits.

V on one another and is against "mg ^ utee- _D · _Druckspa retr so absorbed _by Fasenverkstoff from Matnxmatena _and. ^ In other heg

the case at ^^ "sderstretched, so that the * ^er öanci aer ^ _{between the bevel} rn

Tension can only be _{perceived rial}

f ^ lichai ^ ai ^^ stay tension-free,

came. <aa α _{f the chamfer} rn completely ver ^Man 7 ^ß _e ^e _rri material by axially parallel warp Χ fatigue fractures accepted.

_rota tion symmetrical composite ^ glass staple fibers, glass mats _{"n 'ei} ne rotating spinner o _g _{this Faserwer} kstoff in

The use of a liquid plastic ^bc " ^ie " °. f "" _fBec ker, Schmitz, Weber: ^> ggJJ « ^k ^ plastics«, C.Hansa »° as» chleuae g _58bis71) .

V he lay JMuncn _{ . _{ndun is dunes} ^ _ro t _a tionssym-

Yih to find hollow bodies, the material of which

The invention relates to a rotationally symmetrical ^ SST ^ S.

metric, hollow composite body, consisting of gungen ^^ Object is according to the invention

two also rotationally symmetrical in each other ^ " ^r J ^ nation of the following features are proposed:

arranged seamlessly merging ₅ o the combination te, _wesentl g i _c h _s from

Sn vTn gas centrifuge systems are subject to ver-sden-like Stresses. First of all, there is a high centrifugal force in the wall on Gadder of the machine part has a high tensile stress, the taneential occurs in the plane of rotation. This static tension borrowed in the we-Sn is replaced by further oscillating Tensions superimposed from bending vibrations follow along the axis of the body. The resulting oscillating stresses result Alternating stresses that lead to fatigue failure in the near future.

If the centrifugal forces that occur are very high, the quotient of tensile strength to density must in the material of the machine part should be as high as possible. It is known that the

_{b) The exterior} layer consists of a fiber _who kstoff, in particular from tungsten, ΒβηΛ- _Hunv> steel, boron, Kohkntoff oderStonr karbidfasern, as ψ ^ ^^ Τ Ά. _{a, s} staple fibers or fiber mats angeord _{net sin} ^ ei _wove the joints are sealed between * n "niel · _{nen fibers with} one of said (a) metal.

_{The coefficient of thermal expansion of} the pure _{MetaHg of the inner layer is} equal to or greater than that of the matrix metal of the fiber-reinforced

s _Secretary kth outer layer.

Invention are that a

JJ « _d ^v ^ _{her quotient} ^{6 of} _the tensile strength to the particularly

Density is present in the outer part of the body of revolution that is particularly stressed by centrifugal force; this is achieved in that a composite material, as already mentioned above, forms the outer layer.

This outer part of the composite body has a second, inner part that is seamlessly incorporated pure metal and can therefore absorb considerably higher axial tensile stresses than the Layer of composite material, the fibers of which must run essentially in a tangential direction. Here, at high speed, the fibers take on the centrifugal load of the inner layer, which is caused by this closely to the outer and therefore with flexural vibrations the outer layer supports. In the case of axial tensile stresses, the inner layer supports the outer one and prevents them from stretching beyond the limit of damage, whereby due to the close concern of the a secure connection between them is guaranteed between the two layers.

Lm but also at low speeds a verse ^ To prevent chopping the inner layer against the outer, it is advisable to keep between the two Providing radial prestress to layers; d. H. to shrink the outer layer onto the inner one. Since this is usually used thermal Verahi en, the invention continues to provide for the inner layer to use a metal whose coefficient of thermal expansion is equal to or greater is than that of the matrix metal of the outer layer. It comes from bringing the two hollow-cylindrical layers to a heat balance, then the inner one becomes when it cools down Shorten the layer no less than the outer one, so it becomes a damaging axial one from the start Pre-tensioning the outer layer prevented. A decrease in the radial pretensioning occurs here balanced even at low speed by the pressure force resulting from the centrifugal force.

The material used for the inner layer is one of the metals as it is used as the matrix for the outer layer. This, but especially when using the same material for the Martix and inner layer, results the advantage that, in particular by thermal treatment, an intimate connection between outer and inner layer is produced, whereby delamination phenomena are prevented.

In a further embodiment of the invention, the composite body according to the invention is through Centrifugal casting produced, whereby the metal to be cast is made with the help of a rotating or stationary, Lying in the axis of a rotating mold casting device on the inside wall of the mold lying endless fibers, staple fibers or fiber mats is poured and then the fiber-reinforced layer impregnated with the matrix metal also has a second layer made of a metal is poured on, which has an equal or greater coefficient of thermal expansion ak that Matrix metal by maintaining the rotation of the mold until the metal is

solidified inner layer. It enables this process to optimize the fibers in the casting drum Way to arrange and then subsequently the matrix metal void-free and with more uniform Apply a layer thickness to the fibers.

ίο While the metal is applied to the inner layer is, the matrix metal has already solidified to such an extent that a diffusion zone is still formed between the two layers, but the pressure of the cooling and shortening inner layers Layer withstands, so that there is a high compressive stress in the axial direction in the outer layer, in the inner layer forms a high tensile stress. The magnitude of this tension is of Casting speed, type of melts, materia!

so depends on the mold wall and its thickness and can be controlled using these influencing variables in such a way that such a large preload is selected can be that in the case of transverse deflections of the finished cast body in the outer layer

Pressure-threshold stresses, in the inner layer only allows tensile-threshold stresses to arise. It is This not only prevents damaging tensile stress from being reached in the outer layer, it is also eliminated in addition, the particularly fast to permanent damage

the leading alternating stress, in both shifts. To get radial biases in cheaper Direction is obtained by the rapid rotation of the mold until the inner mold has finally cooled down Shift continued, with this shift in force

solidified in the direction, i.e. plastically deformed radially outwards and pressed against the outer layer, so that after cooling in the radial direction a state of tension is created, as it would otherwise only at a higher speed of the finished cast body

would hire. This not only prevents the detachment phenomena caused by e.g. torsional vibrations would occur, but also invaginations with transverse deflections of the slowly rotating cast body and converting all occurring radial alternating voltages.

When using the method mentioned, it is advantageous to insert it into the casting drum before casting to introduce a framework covered with fiber material and consisting of matrix material. This allows the fibers arranged in the later stress curve corresponding patterns and during the . Approaching the casting drum held in its position until centrifugal force and liquid matrix material prevent the fibers from slipping; the supporting structure then becomes homogeneous with the matrix material merged.

Claims (1)

Patent claims: 1 rotationally symmetrical, hollow composite body, consisting of two rotationally symmetrical, layers arranged one inside the other, seamlessly merging into one another, marked by combining the following features: a) The inner layer consists essentially of metal, in particular of alloys based on nickel, titanium, cobalt or aluminum, "" - sen requirements
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