FI64442B - FOERFARANDE FOER FRAMSTAELLNING AV EN FOER HOEGA PERIPERIHASTIGHETER LAEMPLIG AXEL ELLER TRUMMA - Google Patents

Description

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Patent · och registerstyreleen 'Ansekan utitfd och uti.skrift «n pubiicermd 29.07.83 (32) (33) (31) Pyydetty« Tuoilwu * - Begird prlorltet 10.05.68

Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) P 1750523.6 (71) Maschinenfabrik Augsburg-Nlirriberg Aktiengesellschaft, Katzwanger Strasse 101, 85ΟΟ Nurriberg, Federal Republic of Germany-Förbundsrepubliken Tyskland (DE), (72) Friedrich La La ) (YU) Oy Koister Ab (5U) Method for manufacturing a shaft or drum suitable for high circumferential speeds - Förfarande för framställning av en för höga peripherihastigheter warmplel Axel eller trumma (62) Divided by application 1203/69 - is a method of manufacturing a high circumferential shaft or drum consisting of a hollow, fiber-reinforced synthetic cylinder having a low specific modulus of elasticity (stiffness) and a concentric metal cylinder having a high specific modulus of elasticity therein.

Such cylindrical combinations, i.e. rotors, are widely used in all fields of technology. For example, to improve the tensile strength and corrosion resistance of a printing roll, it is known to surround an inner metal cylinder with a fiber-reinforced, wrapped, or lingo-coated synthetic sheath, as disclosed in U.S. Patent 2,120,875 and German Utility Models 1,914,133 and 1,888,451. Although in these drums the specific modulus of elasticity (specific stiffness), i.e. the ratio of the modulus of elasticity to the thickness, which is generally smaller on the outside than on the inside, is not suitable for fast rotating centrifugal drums, e.g.

U.S. Pat. No. 3,363,479 further discloses a method of manufacturing a rotor having a jacket formed of a material incorporating fibrous particles. The circumferential speed of the rotating body is limited in its magnitude because the substance deforms unimpeded under the influence of centrifugal forces during rotation.

The permissible circumferential speed of the rotor is determined by its structure and the material used. A clean drum rotor, which is essentially formed by a thin-walled cylinder, receives all the centrifugal forces as it rotates in the form of a system formed by tangential stresses.

If these tangential stresses at too high a rotational speed exceed the allowable stresses in the material, the rotor will first become unbalanced due to uncontrolled plastic deformations of the material or will be damaged when the breaking limit is reached locally.

In addition to the permissible stress on the material, the density of the material used is also important for achieving high circumferential speeds. Ingredients with a high elongation limit but low density can reach higher body velocities than substances with a higher density. It is known that fiber-reinforced synthetic materials (e.g., glass-fiber-reinforced synthetic materials) allow stresses comparable to steels and titanium. However, because they have approximately four times lower density, higher circumferential speeds can be achieved. However, rotors with a fiber-reinforced material have significant drawbacks which have hitherto limited their use. The lower modulus of elasticity of the fiber-reinforced synthetic material causes such rotors to be very flexurally elastic and, in addition, to expand too strongly as they rotate.

Attempts have been made in the past to provide rotors for high circumferential speeds. U.S. Pat. No. 3,296,886 discloses a flywheel rotor for generating high torque at high circumferential speeds and having to be low in volume or mass. This rotor consists of a plurality of 3 64442 thin concentric layers made of various, preferably fiber-reinforced materials, the elastic modulus as well as the specific elastic modulus in each case increasing from the inside to the outside. Because the rotor is made of plates, the requirement for flexural strength is omitted. The individual concentric layers are connected to each other by welding or connecting layers. During the initial rotation, of course, the outer layer expands, whereby the next inner layer becomes drawn according to what primarily depends on the quality of the interconnecting layer. As the rotation continues, the inner layers settle against the outer layers because their modulus of elasticity is lower. When the rotor is released from the load, the inner layers rise out of the outer layers, so that in some cases the connecting layer is damaged. This rotor structure acting as an energy accumulator has the disadvantage that it is not suitable for very high circumferential speeds, because the layers are heavier in weight at the outer than at the inside. In addition, since the rotor must not be loaded above the yield point of the innermost, low-resilience layer so that the transverse dimensions do not change substantially, the circumferential speed or operating speed is limited in magnitude. In addition, when the rotor is braked, the layers return to their original dimensions, in which case the layers must be fastened to their original position by means of a connecting layer. In addition, this interconnecting layer can be damaged by alternating stresses, so that the interconnection of the individual layers is lost.

The object of the invention is to provide a shaft or drum whose circumferential speed can be high while the deformation remains small.

This object is solved by the manufacturing method according to the invention, which is characterized in that after assembling the cylinders, the cylinder assembly is loaded radially outwards from the inside over the yield point of the metal cylinder and then the loading is stopped.

Preferably, the prestressing is generated by the first rotation of the cylindrical assembly. Here, the Bauschinger effect in metals is exploited, in which the metal cylinder is loaded beyond its yield point.

There is thus provided a cylinder assembly, i.e. a rotor, the wall thickness of which consists partly of metal, e.g. steel, aluminum or titanium, and partly of fiber-reinforced synthetic material. If this drum rotor is rotated at high speeds, stresses and deformations are created in the metal and the artificial material, which are directly interdependent. According to the high modulus of elasticity of the metal, the stresses increase more rapidly in the metal cylinder than the stresses in the fiber-reinforced active material. At a given speed, the stresses in the metal part reach the yield point. As the speed continues to increase, the inner metal cylinder now undergoes plastic deformation, while the outer fiber-reinforced synthetic cylinder withstands higher elastic stresses. Thus, a shaft or drum is provided, the deformation of which is small even at high circumferential speeds. due to the specific stress state between the individual parts, no interconnecting layer or the like is required.

The dependencies described above are illustrated approximately in Figure 2 for the rotating body of Figure 1 and are explained below using conventional symbols.

According to Figure 1, the rotating body has a metal wall part 1 and a wall part 2 made of fiber-reinforced synthetic material. Figure 2 shows the one-dimensional stresses and strains of a typical metallic material (curve M) and a typical fiber-reinforced synthetic material (curve F). The metallic material, e.g. cast steel, should most preferably have a plastic behavior. The curve = <^ (E) folds horizontally after reaching the yield point. According to the lower modulus of elasticity, the curve F runs substantially more gently than the part O ... o of the curve.

When the cylindrical rotor is rotated at a speed n as described, its angular velocity is ^ = ^ 11/30. Then 3 2 2 = Ϋ * r - lo.

"" * 2 2 The circumferential elongation is Cn = j5 * r - uo. When these simple equations are still used to follow the course of the increase in speed described above, it is observed that, depending on the ratio? N, different tangential elongations and thus radial expansions occur. This situation applies until the yield point is reached in the inner metal cylinder. In this case, it can also happen that the metal cylinder expands less strongly than the GFK joint and thus a momentary detachment of both cylinders takes place. After a certain speed, the yield point is exceeded in the inner metal cylinder. The higher centrifugal forces now caused by the increase in speed must be received by GFK joints. It is clear that the metal cylinder now presses against the artificial cylinder. The radial deformations and circumferential elongations of both cylinders are now similar to each other. If we now assume that a given number of revolutions n ^ corresponds to a common circumferential elongation ^. In addition, if it is assumed that the connecting cylinder is released from the load from this speed, the curve M 'depicts the stress-strain relationship of the metal cylinder (Bauschinger effect). After the artificial joint has still been loaded in a straight line in the resilient region, a connection between the elongations and stresses follows as the speed decreases along the curve F. At a speed of 0, a specific stress state prevails, which causes compressive stresses in the metal cylinder and tensile stresses in the fiber-reinforced synthetic cylinder. The thicknesses of both cylinders and the parameters of their components leave a permanent elongation throughout the cylinder ^ 2 * The tensile stresses of the synthetic cylinder can be and the compressive stresses of the metal cylinder

When the connecting cylinder is reloaded by rotating the rising tensile stresses in the active component from point II along the curve F. The corresponding stresses in the metal part increase from point III along the curve M '. In this case, the compressive stresses first disappear in the metal and tensile stresses are formed in it as the operation continues.

Due to the bias, the connecting rotor behaves quite differently when the rotor is rotated at high revs for the first time. The total radial expansion in both the resilient and plastic case is proportional to the tangential slope of the cylinder, i. during the first phase of rotation, the total expansion of the connecting cylinder is proportional to the distance 0 ... The second load, which occurs at the same speed, has the radial expansion now present proportional to the distance £ 2 ··· £ - | · The deformable coupling rotor thus behaves in the same way as a metal rotor with a higher yield point.

However, due to the lower total thickness of the rotor, substantially higher circumferential speeds can be used than with metal rotors alone.