Device for centrifugal machine test stand

Abstract

The invention relates to a device for a centrifuge test stand (1), comprising a shaft (4), which can be connected to a drive (3) in a rotationally fixed manner via a bearing element (5), and a clamping receptacle (6), which is provided for receiving a rotor (2) to be tested and can be connected to the shaft (4) in a rotationally fixed manner, between the drive (3) and the shaft (4) and between the shaft (4) and the rotor (2), a flexurally elastic spring element (8) is provided. By means of this design, bending forces exerted on the shaft (4) and / or the clamping receptacle (6) as a result of vibrations of the rotor (2) are compensated.

Description

Technical Field

[0001] The invention relates to a device for a centrifuge test bench in which a rotor to be tested is driven in rotation on a flexible shaft. Background Art

[0002] Rotationally symmetrical components are usually subjected to a test process to investigate their fatigue strength, which is carried out on a centrifuge test bench in which the test body is accelerated to a breaking speed or another predetermined speed. In addition, the rotor may be subjected to, for example, periodic speed changes or temperature fluctuations. Such a test bench is known from DE 1 125 206 A.

[0003] In this case, the rotor can be fastened, for example, by its journals, on a thin elastic shaft and accelerated. The rotor then rotates about its inertial axis rather than about its geometric axis, so that the rotor moves almost unaffected by unbalanced forces. Since the elastic natural frequency of the shaft is usually experienced and large deflections can occur in this case, vibration dampers are usually used to limit the deflection of the shaft, so that the amplitude of the centrifugal oscillations can be limited.

[0004] A vibration damping system is known, for example, from DE 102 06 950 A1, which discloses a vertically arranged high-speed rotating test device in which the shaft is supported both on the drive side and on the component side and is connected to the vibration damping system on the component side.

[0005] Document DE 10 2011 087 909 B3 describes a device for a component test bench, which comprises a shaft for transmitting a torque from a rotary drive to a component to be tested, wherein the shaft is rotatably supported in bearings on the component side and the drive side. The component-side bearing is connected to a vibration damping system in a six-leg parallel mechanism, thereby damping vibrations caused by imbalance.

[0006] Furthermore, document DE 28 35 962 A discloses a separator for a centrifuge drum with a vertically extending rotary shaft. The rotary shaft is rotatably held on both sides in fixed bearings and is braced on one side of the centrifuge drum by means of an annular rubber spring. In this way, the resonance level of the centrifuge drum caused by residual imbalance is shifted into a range that is harmless in the operating state by means of yielding bracing.

[0007] Document DE 693 08 430 T2 discloses a centrifuge having a rotor drive shaft, which consists of a flexible shaft surrounded by a sleeve, wherein the shaft and the sleeve are connected to each other in a rotationally fixed manner at one end thereof, while the other end of the flexible shaft projects beyond the other end of the sleeve and has a head for accommodating the rotor of the centrifuge. Means are provided for internal vibration damping and for compensating for possible axis deviations due to assembly errors. This dampens radial movements of the shaft relative to the rotating sleeve. However, this does not produce any external vibration damping for the fixed housing. In addition, the centrifuge comprises an elastic coupling device, which comprises a tubular element made of silicone, into which a pin extends, in order to connect the motor shaft of the drive device to the shaft in a rotationally fixed manner.

[0008] A device for damping rotor vibrations is known from DE 694 04 161 T2.

[0009] In some cases, the component to be tested, for example a rotor, must be centrifugally rotated at a high speed (up to about 30,000 revolutions per minute) at the end of the manufacturing process, so that the individual rotor parts are mounted on each other under the action of centrifugal forces. After this mounting process, a final balancing process is carried out, in which any imbalances in the rotor are compensated. However, if the rotor already has too high an imbalance before the mounting process, damage to the centrifuge test stand may occur due to the imbalance. In order to exclude this, an imbalance compensation can be carried out before the mounting process, but this does not mean that it is superfluous to carry out an imbalance compensation after the actual mounting process.

[0010] The problem with components to be tested with high imbalance is that damage may occur due to stresses and forces in the shaft or the component receptacle. Another disadvantage of the prior art is that rotors with high imbalances must be compensated before the assembly process and therefore multiple complex work steps must be performed. Summary of the invention

[0011] The object of the present invention is to provide a possibility by which, on the one hand, damage to shafts or other components, in particular in the case of high imbalances, can be prevented and, on the other hand, the need for imbalance compensation prior to the assembly process can be eliminated.

[0012] This object is achieved by the features of claim 1. Preferred embodiments are described in the dependent claims.

[0013] The technical problem is solved according to the invention by a device for a centrifuge test bench, the device having a shaft and a clamping receptacle, the shaft being connectable to a drive device in a rotationally fixed manner via a bearing element, the clamping receptacle being provided for receiving a rotor to be tested and being connectable to the shaft in a rotationally fixed manner, characterized in that a flexurally elastic spring element is provided between the drive device and the shaft and between the shaft and the rotor, respectively, the spring element being designed to compensate for bending forces exerted on the shaft and / or the clamping receptacle due to vibrations of the rotor. Forces and stresses that could damage the shaft or the clamping receptacle can be absorbed by the shaping of the spring element. As a result, even rotors with a high degree of imbalance can be tested on a centrifuge test bench without prior balancing, and additional work steps for assembling rotor components during centrifugal rotation are omitted.

[0014] Another advantage of the invention is that a centrifuge test stand of complex and rigid design is not required, since no high unbalance forces are generated. The solution also prevents vibrations generated by an unbalanced rotor from being transmitted to the surroundings in the form of structure-borne sound.

[0015] The spring element is advantageously designed such that it can deform in the direction of the applied bending forces, thereby absorbing and compensating the bending forces acting on the shaft or the clamping receptacle, thereby in particular preventing the shaft or the clamping receptacle from being damaged.

[0016] In one embodiment, it is provided that the clamping receptacle is designed at least partially to be flexibly elastic. Depending on the application, it is advantageous to design the clamping receptacle itself at least partially as a flexibly elastic spring element. This can be achieved, for example, in that the clamping receptacle has a structural component which is connected to the shaft in a force-transmitting manner and has a groove, a recess or a similar flexibly elastic element which absorbs the bending forces acting on the shaft or the clamping receptacle. A similar arrangement can also be made for the support element so that the support element is designed at least partially to be flexibly elastic and comprises a groove or a recess.

[0017] Alternatively, it can be provided that a spring element designed to be flexurally elastic can be connected to the clamping receptacle and the support element, respectively. This means that in this preferred embodiment, it is not a structural component of the clamping receptacle or the support element, but a separate and correspondingly designed component which has the desired physical properties and can be reversibly or irreversibly connected to the support element and the clamping receptacle, respectively.

[0018] The bearing element and the clamping receptacle as well as the spring element preferably have connecting means which enable a structural, in particular force-transmitting, connection to the spring element produced as a separate component.

[0019] The spring element can be designed, for example, as a sleeve-shaped element, which is arranged in a force-transmitting manner between the clamping receptacle and the shaft or between the shaft and the bearing element, wherein the sleeve is designed to be flexurally elastic or at least has a flexurally elastic region. This can be achieved, for example, by a recess, a groove or an integrated spring, which serves to absorb the bending forces acting on the shaft, the clamping receptacle or the bearing element.

[0020] In one embodiment, the support element and / or the clamping receptacle each comprise a spring element designed to be flexurally elastic in the axial direction, which is connected to the shaft force transmittingly and extends radially from the axis of the shaft. The spring element can be designed, for example, as a circular and in particular radially extending diaphragm having a central sleeve-shaped shaft through-hole. The diaphragm is in particular made of a flexurally elastic metal.

[0021] The invention also relates to a centrifuge test bench for testing a rotor, which comprises the aforementioned device. The above advantages and designs also apply to the centrifuge test bench. The advantageous design of the centrifuge test bench enables centrifugal rotation of rotors with a high degree of imbalance. In the context of the invention, the centrifuge test bench can also be referred to as a component test bench. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be described in detail below with reference to the embodiments of the present invention shown in the accompanying drawings. In the accompanying drawings:

[0023] Figure 1 A schematic diagram of a centrifuge test bench according to the prior art is shown,

[0024] Figure 2 The embodiment of the device according to the invention in a centrifuge test bench is schematically shown.

[0025] Figure 3 A sectional view showing a configuration of the device with further components,

[0026] Figure 4 A sectional view showing a design of a support element, and

[0027] Figure 5 A perspective view of the clamping receptacle is shown. DETAILED DESCRIPTION

[0028] Figure 1A schematic diagram of a vertical centrifuge test bench 1 according to the prior art is shown, by which a rotor 2 can be rotated as a test object in order to test its durability under rotational load, etc. The centrifuge test bench 1 includes a drive device 3 for inputting torque in addition to a housing (not shown). The drive device 3 can be designed as an electric motor, for example. The torque of the drive device 3 is transmitted to the vertically extending shaft 4 by connecting the shaft 4 to the drive side in a torque-transmitting manner with a support element 5. The support element 5 can be designed, for example, as a bearing, a coupling device or the like, into which the journal of the shaft 4 engages.

[0029] The rotor-side end of the shaft 4, which is opposite the drive 3, is connected to the rotor 2 in a torque-transmitting manner. The rotor 2 is received and torque-proof clamped in a clamping receptacle 6. The clamping receptacle 6 can be designed differently depending on the shape and structure of the rotor 2. A replaceable clamping receptacle 6 is advantageous here, so that the clamping receptacle 6 can be replaced depending on the test object. The clamping receptacle 6 can be connected to the shaft 4 in a torque-proof manner via a flange connection.

[0030] A vibration damping system 7 is arranged between the bearing element 5 and the clamping receptacle 6 on the shaft 4 and is operatively connected to the shaft 4 by being fixed to the housing. The rotation of the rotor 2 causes an oscillating exciting motion to be damped to be applied to the shaft 4, which causes the shaft 4 to vibrate in the direction of the rotation radius. These vibrations can be damped by the vibration damping system 7.

[0031] The axis of rotation of the rotor 2 to be tested is not determined by the design of the centrifuge test bench 1. The rotor 2 can be moved by means of a substantially freely suspended mounting in such a way that the rotor can freely select the axis of rotation. This means that the unbalanced rotor 2 rotates about its inertia axis and not about a geometric axis, whereby substantially no unbalance forces are generated. Greater unbalances can lead to damage due to stresses and forces in the shaft 4 and the clamping receptacle 6.

[0032] Figure 2 and Figure 3 The design scheme of the present invention is shown, wherein: Figure 4 and Figure 5 A detailed view of the support element and the clamping receptacle is shown. The centrifuge test bench 1 shown here also does not have a housing and the components are shown schematically. According to the invention, Figure 1The known rotor dynamic model shown is extended by two flexurally elastic spring elements 8, which are located between the drive device 3 and the shaft 4 on the drive side and between the shaft 4 and the rotor 2 on the component side or rotor side. The flexurally elastic spring element 8 on the drive side can be arranged in the support element 5 as a diaphragm 9 composed of metal. The diaphragm 9 can be designed in a disc shape and extend radially from the axis of the shaft. The diaphragm 9 transitions into a sleeve-shaped area 10, which is axially against the shaft 4 along the axis of the shaft in a force-transmitting manner. The diaphragm 9 can be flange-connected to the support element 5, for example. That is, the spring element 8 can be fixed to the support element 5 by a flange connection. Deformations caused by the strong imbalance of the rotor 2 and transmitted from the shaft 4 to the support element 5 are intentionally allowed, so as to achieve low loads acting on the support element 5.

[0033] A similar or identical design can be selected between the rotor 2 and the shaft 4 , ie on the rotor side. The spring element 8 can also be designed as a membrane and fastened to the clamping receptacle 6 by means of a flange connection or the like.

[0034] However, it can also be provided that the spring element 8 is designed as a component of the support element 5 or the clamping receptacle 6. For example, the clamping receptacle 6 for receiving the rotor 2 can itself be designed to be flexurally elastic at least in regions and thus be provided as a spring element 8. Here, for example, a recess or groove 11 extending transversely to the axis of the shaft is provided, which can be integrated, for example, in the outer surface of the clamping receptacle 6 and imparts flexurally elastic properties to the clamping receptacle 6. Alternatively, the clamping receptacle 6 can be reversibly or irreversibly connected to the flexurally elastic spring element 8.

[0035] The flexurally elastic spring element 8 is advantageously structurally and force-transmittingly connected to the shaft 4 and absorbs the bending forces acting on the shaft 4. It is advantageous to specify the stiffness of the spring element 8. The use of the spring element 8 according to the invention makes it possible, in particular, to centrifugally rotate the rotor 2 with a large imbalance without the internal stresses and forces generated in the flexible shaft 2 and / or the clamping receptacle 6 reaching unacceptable values ​​and causing damage to them. The spring element 8 does not have vibration-damping properties. Instead, the deformation of the rotor 2 is yielded by the spring element 8 according to the invention and its positioning, since the rotor is oriented about its center of gravity axis. For this purpose, it is advantageous if the system is designed to be sufficiently soft to achieve low loads in the bearing element 5 and the clamping receptacle 6.

Claims

1. A device for a centrifuge test bench (1), comprising a shaft (4) which can be connected to a drive device (3) in a rotationally fixed manner via a bearing element (5), and a clamping receptacle (6), which is provided for receiving a rotor (2) to be tested and can be connected to the shaft (4) in a rotationally fixed manner, characterized in that: A flexurally elastic spring element (8) is provided between the drive device (3) and the shaft (4) and between the shaft (4) and the rotor (2), respectively, and is designed to compensate for bending forces exerted on the shaft (4) and / or the clamping receptacle (6) due to vibrations of the rotor (2).

2. The device according to claim 1, characterized in that A spring element (8) designed to be flexurally elastic can be connected to the clamping receptacle (6).

3. The device according to claim 1, characterized in that The support element (5) can be connected to a spring element (8) which is designed to be flexurally elastic.

4. The device according to claim 1, characterized in that The support element (5) is designed to be flexurally elastic at least in regions.

5. The device according to claim 1, characterized in that The clamping receptacle (6) is designed at least in regions to be flexurally elastic.

6. The device according to any one of claims 1 to 3, characterized in that The bearing element (5) and / or the clamping receptacle (6) each comprises a spring element (8) which is designed to be flexurally elastic in the axial direction, is connected to the shaft (4) in a force-transmitting manner and extends radially from the axis of the shaft.

7. The device according to claim 6, characterized in that The spring element (8) is arranged in the support element (5) as a circular diaphragm which has a central, sleeve-shaped shaft passage opening.

8. The device according to claim 7, characterized in that The diaphragm consists of a flexurally elastic metal.

9. The device according to claim 5, characterized in that The flexurally elastic region of the clamping receptacle (6) comprises a recess or groove (11) extending transversely to the axis of the shaft.

10. The device according to any of the preceding claims, characterized in that The spring element (8) is designed such that it can be deformed in the direction of an acting bending force.

11. A centrifuge test rig for testing rotors, comprising a device according to one of the preceding claims.

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