Arrangement for a spin test bench

Abstract

In an arrangement for a spin test bench (1) with a shaft (4) that is able to be connected in a rotationally fixed manner to a drive (3) via a bearing element (5) and with a clamping holder (6) that is intended for receiving a rotor (2) to be tested and able to be connected in a rotationally fixed manner to the shaft (4), the invention proposes that a flexible spring element (8) is provided between the drive (3) and shaft (4), and between the shaft (4) and rotor (2). The design compensates bending forces acting on the shaft (4) and / or clamping holder (6) caused by vibration of the rotor (2).

Description

[0001] ARRANGEMENT FOR A SPIN TEST BENCH

[0002] The invention relates to an arrangement for a spin test bench in which a rotor to be tested is driven in rotation on a flexible shaft.

[0003] To determine their fatigue strength, rotationally symmetrical components are typically subjected to a test procedure performed on a spin test rig, where the test specimens are spun to burst speed or another predefined speed. In addition, the rotor can be subjected to cyclic speed changes or temperature fluctuations, for example. Such a test rig is known from DE 1 125206 A.

[0004] The rotor can be suspended from a thin, elastic shaft, for example, via its shaft journal, and accelerated. The rotor then rotates around its mass axis of inertia instead of its geometric axis, so that the rotor moves virtually free of imbalance forces. Since the shaft's elastic natural frequencies are usually passed through, and large deflections can occur, dampers are often used to limit the shaft deflection, thus limiting the amplitudes of the spin waves.

[0005] Damping systems are known, for example, from DE 102 06 950 A1, which discloses a vertically arranged high-speed rotation test device in which the shaft is mounted on both the drive and component sides and is connected to a damping system on the component side.

[0006] DE 10 2011 087 909 B3 describes an arrangement for a component test bench, comprising a shaft for transmitting torque from a rotary drive to a component under test. The shaft is rotatably mounted in a bearing on both the component and drive sides. The component-side bearing is connected to a damping system in a hexapod arrangement, so that vibrations generated by imbalance are damped.

[0007] Furthermore, DE 28 35 962 A discloses a separator with a vertically extending rotating shaft for a centrifuge drum. The rotating shaft is rotatably mounted on both sides in fixed bearings and is held under tension on the centrifuge drum side by means of an annular rubber spring. In this way, the resilient tension shifts the resonance position of the centrifuge drum due to residual imbalance into a range that is harmless during operation.

[0008] DE 693 08 430 T2 discloses a centrifuge with a rotor drive shaft formed by a flexible shaft surrounded by a sleeve. The shaft and the sleeve are connected to one another in a rotationally fixed manner at one end, while the other end of the flexible shaft projects beyond the other end of the sleeve and carries a head that serves to accommodate the centrifuge's rotor. Means are provided for internal damping and to compensate for any axial misalignment caused by assembly errors. This dampens radial movement of the shaft relative to the rotating sleeve. However, this does not create any external damping relative to the stationary housing. The centrifuge also includes an elastic coupling containing tubular elements made of silicone into which pins protrude to connect the motor shaft of the drive to the shaft in a rotationally fixed manner.

[0009] A device for damping rotor vibrations is known from DE 694 04 161 T2.

[0010] In some cases, components to be tested, such as rotors, must be centrifuged at high speeds (up to approximately 30,000 rpm) at the end of the manufacturing process so that the individual rotor components are seated together due to centrifugal force. Following this seating process, a final balancing process takes place to correct any existing rotor imbalance. However, if the rotors are already excessively unbalanced prior to the seating process, the imbalance may cause damage to the spin test rig. To prevent this, unbalance correction can be performed prior to the seating process, although this does not eliminate the need for unbalance correction after the actual seating process.

[0011] Particularly problematic for components to be tested that exhibit high levels of imbalance is that damage can occur due to stresses and forces in the shaft or component mount. Another disadvantage of the current state of the art is that rotors with high levels of imbalance must be balanced before the setting process, thus requiring several complex work steps.

[0012] The invention is based on the object of providing a possibility by which, on the one hand, damage to the shaft or other components can be prevented, especially in the case of high imbalances, and, on the other hand, an unbalance compensation before the setting process becomes unnecessary.

[0013] The problem is solved by the features of claim 1. Preferred embodiments are described in the dependent claims.

[0014] The object is achieved according to the invention in that an arrangement for a spin test bench is provided, with a shaft which can be connected in a rotationally fixed manner to a drive via a bearing element and a clamping fixture which is provided for receiving a rotor to be tested and which can be connected in a rotationally fixed manner to the shaft, characterized in that a flexurally elastic spring element is present between the drive and the shaft and between the shaft and the rotor, which is designed in such a way that bending forces exerted on the shaft and / or clamping fixture by vibration of the rotor are compensated. The design of the spring elements absorbs forces and stresses which could potentially lead to damage to the shaft or the clamping fixture. This means that even rotors with high imbalances can be tested in the spin test bench without prior compensation and the additional work step during the spinning process for setting the rotor components is eliminated.

[0015] A further advantage of the invention is that complex, fixed spin test stands are not required, since high imbalance forces are eliminated. Furthermore, the solution prevents vibrations from the unbalanced rotor from being radiated into the environment in the form of structure-borne noise.

[0016] The spring elements are advantageously designed to allow deformation of the spring elements in the direction of an applied bending force. This allows bending forces acting on the shaft or clamping fixture to be absorbed and compensated, thereby preventing damage to the shaft or clamping fixture.

[0017] In one embodiment, the clamping receptacle is designed to be flexurally elastic, at least in some regions. Depending on the application, it may be advantageous for the clamping receptacle itself to be designed, at least in some regions, as a flexurally elastic spring element. This can be achieved, for example, by the clamping receptacle having a structural component that is connected to the shaft in a force-transmitting manner and has slots, recesses, or similar flexurally elastic elements that absorb bending forces acting on the shaft or the clamping receptacle. A similar design can be provided for the bearing element, so that the bearing element is designed to be flexurally elastic, at least in some regions, and comprises slots or recesses.

[0018] Alternatively, it can be provided that a flexible spring element can be connected to the clamping receptacle and the bearing element. This means that in this preferred embodiment, it is not a structural component of the clamping receptacle or the bearing element, but rather a separate and appropriately designed component that has the desired physical properties and can be reversibly or irreversibly connected to the bearing element and clamping receptacle.

[0019] Preferably, the bearing element and clamping receptacle as well as the spring elements have connecting means which enable a structural, in particular force-transmitting, connection with the spring element manufactured as a separate component.

[0020] The spring elements can, for example, be designed as sleeve-like elements that transmit force between the clamping fixture and the shaft, or between the shaft and the bearing element. The sleeves are designed to be flexible or at least have flexible areas. This can be achieved, for example, through recesses, slots, or integrated springs that absorb the bending forces acting on the shaft, clamping fixture, or bearing element.

[0021] In one embodiment, the bearing element and / or the clamping receptacle each comprise a spring element that is axially flexible and elastically connected to the shaft in a force-transmitting manner and extends radially from the shaft axis. The spring element can be provided, for example, as a circular and, in particular, radially extending membrane with a central sleeve-shaped shaft passage. The membrane is formed, in particular, from a flexible metal.

[0022] The invention also relates to a spin test bench for testing a rotor, comprising a previously described arrangement. The explained advantages and configurations are analogously applicable to the spin test bench. The advantageous design of the spin test bench allows for the spin testing of rotors with high imbalances. A spin test bench can also be referred to as a component test bench within the meaning of the invention.

[0023] The invention will be explained in more detail below with reference to an embodiment of the invention, which is illustrated in the drawing.

[0024] Figure 1 is a schematic representation of a spin test bench according to the state of the art,

[0025] Figure 2 shows an embodiment of the arrangement according to the invention in a schematically illustrated spin test bench,

[0026] Figure 3 is a sectional view of an embodiment of the arrangement with further components,

[0027] Figure 4 is a sectional view of an embodiment of a bearing element and Figure 5 is a perspective view of a clamping receptacle.

[0028] Figure 1 shows a schematic representation of a vertical spin test rig 1 according to the prior art, with which a rotor 2 as a test object can be set in rotation in order to test its durability or the like under rotational load. A spin test rig 1 comprises, in addition to a housing (not shown), a drive 3 for supplying torque. The drive 3 can be designed, for example, as an electric motor. The torque of the drive 3 is transmitted to a vertically extending shaft 4 by connecting the shaft 4 on the drive side to the drive 3 via a bearing element 5 in a torque-transmitting manner. The bearing element 5 can be designed, for example, as a bearing, coupling, or the like, into which the shaft journal of the shaft 4 engages.

[0029] The rotor-side end of shaft 4 opposite drive 3 is connected to rotor 2 for torque transmission. Rotor 2 is accommodated in a clamping fixture 6 and clamped in a rotationally fixed manner. The clamping fixture 6 can be constructed differently depending on the shape and structure of rotor 2. An interchangeable clamping fixture 6 is advantageous here, so that the clamping fixture 6 can be changed depending on the test object. The clamping fixture 6 can be connected to shaft 4 in a rotationally fixed manner via a flange connection.

[0030] A damping system 7 is arranged on the shaft 4 between the bearing element 5 and the clamping fixture 6. It is operatively connected to the shaft 4 by means of a housing. Rotation of the rotor 2 imparts an oscillating excitation movement to the shaft 4, which is to be damped, leading to vibrations of the shaft 4 in the direction of the rotation radius. These vibrations can be damped by the damping system 7.

[0031] Due to the design of the spin test rig 1, the rotational axis of the rotor 2 being tested is not fixed. Due to the essentially freely suspended bearings, the rotor 2 can move in such a way that it can freely choose its rotational axis. This means that unbalanced rotors 2 rotate around their mass axis of inertia instead of their geometric axis, which essentially results in no unbalance forces. Larger imbalances can lead to damage due to stresses and forces in the shaft 4 and the clamping fixture 6.

[0032] Figures 2 and 3 show embodiments of the invention, with Figures 4 and 5 showing detailed views of the bearing element and the clamping fixture. The spin test bench 1 is also shown without a housing here, and the components are shown schematically. The known rotordynamic model shown in Figure 1 is expanded according to the invention by two flexurally elastic spring elements 8, which are located on the drive side between the drive 3 and the shaft 4 and on the component side, or rotor side, between the shaft 4 and the rotor 2. The drive-side flexurally elastic spring element 8 can be provided as a metal membrane 9 in the bearing element 5. The membrane 9 can be plate-shaped and extend radially from the shaft axis. The membrane 9 merges into a sleeve-shaped region 10, which bears axially against the shaft 4 along the shaft axis in a force-transmitting manner. The membrane 9 can, for example, be flange-mounted on the bearing element 5.This means that the spring element 8 can be attached to the bearing element 5 via a flange connection. Deformations resulting from a significant imbalance of the rotor 2 and transmitted from the shaft 4 to the bearing element 5 are deliberately allowed, so that a low load on the bearing element 5 is achieved.

[0033] A similar or identical design can be selected between rotor 2 and shaft 4, i.e., on the rotor side. Here, the spring element 8 can also be designed as a membrane and attached to the clamping fixture 6 via a flange connection or the like.

[0034] However, it can also be provided that the spring elements 8 are designed as a component of the bearing element 5 or the clamping holder 6.

[0035] For example, the clamping fixture 6 for holding the rotor 2 can be designed to be flexurally elastic, at least in some areas, and thus be provided as a spring element 8. Examples include recesses or slots 11 running transversely to the shaft axis, which can be integrated, for example, into the casing of the clamping fixture 6 and impart flexurally elastic properties to the clamping fixture 6. Alternatively, the clamping fixture 6 can be reversibly or irreversibly connected to a flexurally elastic spring element 8.

[0036] The flexurally elastic spring elements 8 are advantageously structurally and force-transmittingly connected to the shaft 4 and absorb bending forces acting on the shaft 4. A defined stiffness of the spring elements 8 is advantageous. The use of the spring elements 8 according to the invention enables, in particular, the spinning of rotors 2 with large imbalances without the occurring internal stresses and forces in the flexible shaft 2 and / or the clamping fixture 6 reaching unacceptable values ​​and resulting in damage. The spring elements 8 have no damping properties. Rather, the spring elements 8 according to the invention and their positioning ensure that deformations of the rotor 2 are accommodated, as the rotor 2 aligns itself around its center of gravity. For this purpose, it is advantageous if the system is designed to be soft enough to achieve low loads in the bearing element 5 and the clamping fixture 6.

Claims

PATENT CLAIMS Arrangement for a centrifuge test stand (1) with a shaft (4) that can be connected in a rotationally fixed manner to a drive (3) via a bearing element (5), and with a clamping receptacle (6) provided for receiving a rotor (2) to be tested and that can be connected in a rotationally fixed manner to the shaft (4), characterized in that a flexurally elastic spring element (8) is present between the drive (3) and the shaft (4) and between the shaft (4) and the rotor (2), which is designed such that bending forces exerted on the shaft (4) and / or the clamping receptacle (6) by vibration of the rotor (2) are compensated. Arrangement according to claim 1, characterized in that a flexurally elastic spring element (8) can be connected to the clamping receptacle (6). Arrangement according to claim 1, characterized in that the bearing element (5) can be connected to a flexurally elastic spring element (8).Arrangement according to claim 1, characterized in that the bearing element (5) is designed to be flexurally elastic at least in some regions. Arrangement according to claim 1, characterized in that the clamping receptacle (6) is designed to be flexurally elastic at least in some regions. Arrangement according to one of the preceding claims 1 to 3, characterized in that the bearing element (5) and / or the clamping receptacle (6) each have a force-transmitting connection to the shaft (4). connected and extending radially from the shaft axis, an axially flexurally elastic spring element (8). Arrangement according to claim 6, characterized in that the spring element (8) is provided in the bearing element (5) as a circular membrane with a central sleeve-shaped shaft passage. Arrangement according to claim 7, characterized in that the membrane is formed from a flexurally elastic metal. Arrangement according to claim 5, characterized in that the flexurally elastic regions of the clamping receptacle (6) comprise recesses or slots (11) running transversely to the shaft axis. Arrangement according to one of the preceding claims, characterized in that the spring elements (8) are designed such that deformation of the spring elements (8) in the direction of an acting bending force is possible. Spin test bench for testing a rotor, comprising an arrangement according to one of the preceding claims.

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