Academic literature on the topic 'Hirth coupling'
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Journal articles on the topic "Hirth coupling"
1
Croccolo, Dario, Massimiliano De Agostinis, Stefano Fini, Giorgio Olmi, Francesco Robusto, and Nicolò Vincenzi. "On Hirth Ring Couplings: Design Principles Including the Effect of Friction." Actuators 7, no. 4 (November 21, 2018): 79. http://dx.doi.org/10.3390/act7040079.
Full textAbstract:
Rings with Hirth couplings are primarily used for the accurate positioning of axial-symmetric components in the machine tool industry and, generally, in mechanical components. It is also possible to use Hirth rings as connection tools. Specific industries with special milling and grinding machines are able to manufacture both tailor made and standard Hirth rings available on stock. Unfortunately, no international standard (for instance ISO, DIN or AGMA) is available for the production and the design of such components. In the best-case scenario, it is possible to find simplified design formulae in the catalogue of the suppliers. The aim of this work is to provide some accurate formulae and computational methods for design to provide better awareness on the limitations and the potential of this type of connection. The work consists of five parts: (i) a review of the base calculation derived mainly from the catalogues of manufacturers; (ii) an improved calculation based on a new analytical method including the friction phenomenon; (iii) an experimentation run for validating the method; (iv) a case study applied to a machine tool; and, (v) a closed form formulation to determine an upper threshold for friction, thus ensuring the Hirth coupling regular performance.
2
Du, Chao, Jun Zhang, Dun Lu, Huijie Zhang, and Wanhua Zhao. "A parametric modeling method for the pose-dependent dynamics of bi-rotary milling head." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 232, no. 5 (July 6, 2016): 797–815. http://dx.doi.org/10.1177/0954405416654599.
Full textAbstract:
Bi-rotary milling head is one of the core components of five-axis machining center, and its dynamic characteristics directly affect the machining stability and accuracy. During the sculptured surface machining, the bi-rotary milling head exhibits varying dynamics in various machining postures. To facilitate rapid evaluation of the dynamic behavior of the bi-rotary milling head within the whole workspace, this article presents a method for parametrically establishing dynamic equation at different postures. The rotating and swing shafts are treated as rigid bodies. The varying stiffness of the flexible joints (such as bearings and hirth coupling) affected by gravity and cutting force at different swing angles is analyzed and then a multi-rigid-body dynamic model of the bi-rotary milling head considering the pose-varying joint stiffness is established. The Lagrangian method is employed to deduce the parametric dynamic equation with posture parameters. The static stiffness, natural frequencies and frequency response functions at different postures are simulated using the parametric equation and verified by the impact testing experiments. The theoretical and experimental results show that the dynamics of the bi-rotary milling head vary with the machining postures, and the proposed method can be used for efficient and accurate evaluation of the pose-dependent dynamics at the design stage.
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Kim, Baik Jin, Joseph Oh, and Alan Palazzolo. "Test and Theory for a Refined Structural Model of a Hirth Coupling." Journal of Engineering for Gas Turbines and Power, August 10, 2021. http://dx.doi.org/10.1115/1.4052088.
Full textAbstract:
Abstract Hirth coupling transmits high torques in the rotating assemblies of compressors and turbines. Their mating surface contacts cause local changes in lateral shaft stiffness. This is affected by the teeth geometry, contact surface area, coupling preload, and surface finish at the contact faces. Industry practice ignores localized lateral flexibility from the Hirth coupling, or is guided by limited experience-based rules of thumb. The authors provide a novel modeling approach utilizing 3D solid finite elements which accounts for contact deformations, intricate interface teeth geometries, stress concentration, and surface finish. This provides an increased accuracy localized stiffness model for the Hirth coupling, to improve rotordynamic response predictions. Free-free natural frequencies of a test rotor including a Hirth coupling are experimentally measured. The rotor is instrumented with strain gauges for preload force measurements, and the Hirth coupling contacting surface profiles are measured with a stylus type surface profiler. A GW contact model is obtained from the measured surface profiles. An iterative computation algorithm is utilized to calculate Hirth coupling contact stiffness and contact pressure at the complex-shaped contact surfaces. Predicted and measured natural frequencies are compared vs. preload.
4
Du, Chao, Jun Zhang, Dun Lu, Huijie Zhang, and Wanhua Zhao. "Coupled Model of Rotary-Tilting Spindle Head for Pose-Dependent Prediction of Dynamics." Journal of Manufacturing Science and Engineering 140, no. 8 (June 1, 2018). http://dx.doi.org/10.1115/1.4040155.
Full textAbstract:
Five-axis machine with rotary-tilting spindle head (RTSH) is always used for sculptured surface machining, and the tool-tip dynamics in various machining postures along the tool path directly affect the machining accuracy and stability. To rapidly evaluate the tool-tip dynamics at different postures during the structural design of tool-spindle-spindle head (TSSH) assembly, this paper proposes a coupled dynamic model of tool-spindle-bearing system (TSBS) and RTSH. The model is a rigid-flexible multibody dynamic model with 36 degrees-of-freedom (DOFs), where in the rotary shaft, swivel shaft and housing are treated as rigid bodies; the tool, tool holder, and spindle shaft are modeled by reduced beams; the bearings and flexible joints are modeled as spring-damping elements. The fully Cartesian coordinates and Lagrangian method are employed to deduce a general parametric dynamic equation. The analytical method for calculating the contact stiffness of bearings and flexible joints is systematically presented, including tool-holder joint, holder-spindle joint, spindle bearings, hirth coupling, and the bearings and locking joints of rotary and swivel shafts. The model is verified by the frequency response functions (FRFs) testing and modal testing at different postures. The experimental results show that the proposed model can be used for accurate and efficient evaluation of the tool-tip FRFs, natural frequencies and mode shapes of TSSH at an arbitrary posture.
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Rimpel, Aaron M., and Matthew Leopard. "Simple Contact Stiffness Model Validation for Tie Bolt Rotor Design With Butt Joints and Pilot Fits." Journal of Engineering for Gas Turbines and Power 142, no. 1 (December 5, 2019). http://dx.doi.org/10.1115/1.4045102.
Full textAbstract:
Abstract Tie bolt rotors for centrifugal compressors comprise multiple shaft components that are held together by a single tie bolt. The axial connections of these rotors—including butt joints, Hirth couplings, and Curvic couplings—exhibit a contact stiffness effect, which tends to lower the shaft bending frequencies compared to geometrically identical monolithic shafts. If not accounted for in the design stage, shaft bending critical speed margins can be compromised after a rotor is built. A previous paper had investigated the effect of tie bolt force on the bending stiffness of stacked rotor assemblies with butt joint interfaces, both with and without pilot fits. This previous work derived an empirical contact stiffness model and developed a practical finite element modeling approach for simulating the axial contact surfaces, which was validated by predicting natural frequencies for several test rotor configurations. The present work built on these previous results by implementing the same contact stiffness modeling approach on a real tie bolt rotor system designed for a high pressure centrifugal compressor application. Each joint location included two axial contact faces, with contact pressures up to five times higher than previously modeled, and a locating pilot fit. The free-free natural frequencies for different amounts of tie bolt preload force were measured, and the frequencies exhibited the expected stiffening behavior with increasing preload. However, a discontinuity in the data trend indicated a step-change increase in the contact stiffness. It was shown that this was likely due to one or more of the contact faces becoming fully engaged only after sufficient tie bolt force was applied. Finally, a design calculation was presented that can be used to estimate whether contact stiffness effects may be ignored, which could simplify rotor analyses if adequate contact pressure is used.
Dissertations / Theses on the topic "Hirth coupling"
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Vazovan, Ľubomír. "Vřeteník a naklápěcí hlava frézovacího multifunkčního obráběcího centra s vodorovnou osou vřetena." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-402637.
Full textAbstract:
The thesis contains of draft, calculations, CAD model and drawing documentation of the moltifunctional machining center with horizontal axis of spindle. This thesis is one of the four parts with which connection ensue the machine-tool. In the first part of my work, there is a constructional draft of the headstock which will enable milling, turning and drilling. In the introduction of this part is headstock research which is solving the most important parts of the headstock of machine . Consequently, technical calculations are acoomplished. Based on these calculations, a specific constructional draft of the headstock is crafted. In the next part of my work, I do research in the area of removable paring milling heads. After this part, there are technical calculations and the specific constructional draft. In the entire work, there is emphasis put on simplicity and functionality.
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Navrátil, Lukáš. "Konstrukce revolverové hlavy pro CNC soustruh." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400930.
Full textAbstract:
This thesis deals with mechanical design of tool turret for CNC lathe. The first part of the thesis is dedicated to research of automatic tool exchange and current trends in design of tool turrets with drive of rotary tools. The second part is focused to design of tool turret, which is based on the findings of the research part of the thesis. The design includes calculations of machining loads, spindle deformation, bearings, gears and spindle startup. Furthermore, 3D models and selected drawings are included.
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Horák, Vítězslav. "Konstrukce frézovací hlavy pro CNC soustruh s nastavitelným sklonem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417456.
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This thesis deals with design of CNC lathe milling head with B axis. Thesis includes research in CNC turning machines, their tool systems and overview of manufacturers of milling B axis. It also includes calculation of machining forces, design of spindle and design of B axis including necessary calculations. Part of this thesis is also 3D model and assembly drawing, 2 manufacturing drawings and list of items.
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Dadfar, Seyed Mohammad Mahdi [Verfasser], and M. [Akademischer Betreuer] Hirtz. "Coupling Chemistry for Surface Immobilization in Scanning Probe Lithography / Seyed Mohammad Mahdi Dadfar ; Betreuer: M. Hirtz." Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1196208794/34.
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Mareček, Vojtěch. "Otočný polohovací stůl." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-264921.
Full textAbstract:
This diploma thesis deals with projection and general design of rotary indexing table for dedicated machine tools. The major attention is given to substitution of hydraulic drive table by table driven by servomotor, namely double axis its positions in vertical and horizontal directions. The total configuration of rotary table is solved as a construction kit, user can used any servomotor and additive gearbox. The work is concentrated to the optimization of table construction for this new designed conception. The positioning and fixing of table plate is solved by couple of Hirth couplings with central hydraulic motor. The computational part of work includes calculations of dynamic of rotary motion of the table and hydraulic system. All important screw connection, gear wheels and Hirth couplings were verified by calculations. Also working lifetime of bearings and strength deformation of major constructional sections of rotary table verification were controlled. Inherent part of work is security analysis, economics analysis, patent search and analysis of construction identity. Presented work contains three-dimensional model, drawing documentation of both variants of configurations and production drawing of major section parts of rotary table.
Conference papers on the topic "Hirth coupling"
1
Kim, Baik Jin, Joseph Oh, and Alan Palazzolo. "Test and Theory for a Refined Structural Model of a Hirth Coupling." In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-59970.
Full textAbstract:
Abstract Hirth coupling transmits high torques in the rotating assemblies of compressors and turbines. Their mating surface contacts cause local changes in lateral shaft stiffness. This is affected by the teeth geometry, contact surface area, coupling preload, and surface finish at the contact faces. Industry practice ignores localized lateral flexibility from the Hirth coupling, or is guided by limited experience-based rules of thumb. The authors provide a novel modeling approach utilizing 3D solid finite elements which accounts for contact deformations, intricate interface teeth geometries, stress concentration, and surface finish. This provides an increased accuracy localized stiffness model for the Hirth coupling, to improve rotordynamic response predictions. Free-free natural frequencies of a test rotor including a Hirth coupling are experimentally measured. The rotor is instrumented with strain gauges for preload force measurements, and the Hirth coupling contacting surface profiles are measured with a stylus type surface profiler. A GW contact model is obtained from the measured surface profiles. An iterative computation algorithm is utilized to calculate Hirth coupling contact stiffness and contact pressure at the complex-shaped contact surfaces. Predicted and measured natural frequencies are compared vs. preload.
2
Liu, Yang, Qi Yuan, and Zuo Zhou. "Contact Status Analysis of Rod-Fastened Rotors With Hirth Coupling in Gas Turbines." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42816.
Full textAbstract:
The aim of this paper is to provide some basis for the design and assembly of a rod-fastened rotor with Hirth coupling. The rod-fastened rotor is comprised of a series of discs clamped together by a central tie rod or several tie rods on the pitch circle diameter. The key difference between a rod-fastened rotor and an integrated one is the existence of contact interfaces. The contact status of contact interface in the rod-fastened rotor is the key concern for accurate rotor dynamic analysis. Therefore, the method of accurately describing the slippage status and contact status is presented in this paper. The approach of eliminating the slippage and making the radial contact pressure distribution more uniform is also presented. According to the characteristics of Hirth coupling, one model of a turbine end rotor with Hirth coupling of a heavy duty gas turbine was built. The three-dimensional finite element contact method and non-linear behaviors such as friction were also taken into account. The effect of pre-tightening forces, centrifugal forces and overhung rim lengths on the radial slippage including initial radial slippage usi and dynamic radial slippage usd of contact interface was determined. A dimensionless coefficient cr was also defined to describe the radial contact pressure distribution of contact interface which was influenced by the values of pre-tightening forces, centrifugal forces and wheel rim lengths respectively. The results of Hirth coupling indicate that the initial radial slippage increases with the pre-tightening forces, and for a fixed pre-tightening force, usi decreased with the increase of overhung rim length. In addition, there is an optimum rim length to eliminate the dynamic radial slippage usd produced by the change of the centrifugal force. Through the analysis of contact pressure distribution, we know that the reasonable design of the load relief trough processed in the overhung rim makes the contact pressure distribution more uniform. Finally, the effect of temperature load on the radial slippage and contact pressure distribution was investigated.
3
Liu, Xin, Qi Yuan, Yang Liu, and Jin Gao. "Analysis of the Stiffness of Hirth Couplings in Rod-Fastened Rotors Based on Experimental Modal Parameter Identification." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26448.
Full textAbstract:
Hirth couplings are widely used to transport torque between discs in turbine machinery for the advantages of precise centering, reliable positioning and excellent structural stability. However, the stiffness of the rotor segment with Hirth couplings is less than that of the integrated structure because it is weaken in the discontinuous structure. For the rotor segment with Hirth couplings, there are two types of contact status depending on the relationship between the separate stress and the compression stress. The first type is that the whole zone of Hirth couplings is in contact, where all of the Hirth couplings make contribution to the stiffness of the rotor segment. The second type of contact status is that some zones of the Hirth couplings are separated, where the equivalent stiffness of the rotor segment is only determined by the zones which are in contact. Obtaining accurate stiffness of Hirth couplings is of great significance in rotor dynamic performance analysis. In this study, the flexural stiffness of Hirth couplings of a gas turbine was calculated by three dimensional (3D) nonlinear contact Finite Element Method (FEM), and based on which the natural frequencies of a rod-fastened rotor were investigated. The stiffness modifying method which modifies the elasticity modulus of the material in the connection segment was used to conduct modal analysis in order to evaluate the effect of the stiffness weakening of the Hirth couplings. One experimental rotor with Hirth couplings and a central tie rod was designed to verify the theoretical and numerical analysis results. According to the results, the stiffness coefficient is constant when the load factor γ is less than 1.0, which means the stiffness of the Hirth couplings segment is almost constant when the pre-tightening force is large enough to keep the whole zone of the Hirth couplings in contact. The stiffness coefficient constant is about 0.32 (specific for the investigated model). And the stiffness coefficient drops dramatically when the load factor γ exceeds 1.0, which indicates that the stiffness of the Hirth couplings segment decreases dramatically since the pre-tightening force is insufficient and the Hirth couplings are separated. The Hirth couplings segment stiffness obtained by experimental modal parameter identification turned out to be consistent with the calculated results by FEM. The modified stiffness of the Hirth couplings segment were applied on the dynamic performance analysis of a real gas turbine rotor and the accuracy of calculating results was improved.
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Janssen, Manfred J., and John S. Joyce. "35-Year Old Splined-Disc Rotor Design for Large Gas Turbines." In ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-523.
Full textAbstract:
The design principles of the splined-disc-type rotor with Hirth-serration couplings used in all Siemens heavy-duty gas turbines since 1960 are explained. The benefits of this rotor construction are elaborated against the operational requirements imposed on rotors by present-day large advanced gas turbines for electric power generation. Details of the stress assessment, analysis and testing underlying the design, as well as a description of the assembly of the rotor are also presented, using mostly the 170 MW-class 3600 rpm Model V84.3A gas turbine to illustrate the most recent technology.
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Rimpel, Aaron M., and Matthew Leopard. "Simple Contact Stiffness Model Validation for Tie Bolt Rotor Design With Butt Joints and Pilot Fits." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90396.
Full textAbstract:
Abstract Tie bolt rotors for centrifugal compressors comprise multiple shaft components that are held together by a single tie bolt. The axial connections of these rotors — including butt joints, Hirth couplings, and Curvic couplings — exhibit a contact stiffness effect, which tends to lower the shaft bending frequencies compared to geometrically identical monolithic shafts. If not accounted for in the design stage, shaft bending critical speed margins can be compromised after a rotor is built. A previous paper had investigated the effect of tie bolt force on the bending stiffness of stacked rotor assemblies with butt joint interfaces, both with and without pilot fits. This previous work derived an empirical contact stiffness model and developed a practical finite element modeling approach for simulating the axial contact surfaces, which was validated by predicting natural frequencies for several test rotor configurations. The present work built on these previous results by implementing the same contact stiffness modeling approach on a real tie bolt rotor system designed for a high pressure centrifugal compressor application. Each joint location included two axial contact faces, with contact pressures up to five times higher than previously modeled, and a locating pilot fit. The free-free natural frequencies for different amounts of tie bolt preload force were measured, and the frequencies exhibited the expected stiffening behavior with increasing preload. However, a discontinuity in the data trend indicated a step-change increase in the contact stiffness. It was shown that this was likely due to one or more of the contact faces becoming fully engaged only after sufficient tie bolt force was applied. Finally, a design calculation was presented that can be used to estimate whether contact stiffness effects may be ignored, which could simplify rotor analyses if adequate contact pressure is used.
6
Vannini, Giuseppe. "Rotordynamic Validation of an Ultra High Speed Multistage Centrifugal Compressor Stacked Rotor." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-27339.
Full textAbstract:
The author’s company is currently developing some centrifugal compressor prototypes where the traditional rotor design based on shrunk on wheels and spacers is not suitable due to the specific service requirements (e.g. high peripheral speed or high temperature). For instance the development of a new centrifugal compressor technology aimed to reduce the number of compressor units needed to fulfill a given service is ongoing. In order to accomplish this challenging target a very high rotational speed is required together with special “high pressure ratio” centrifugal stages. The rotor mechanical configuration which has been selected here is a stacked configuration where each centrifugal wheel is integral with the relevant shaft portion. The several shaft portions are mated together through high precision toothed connections (Hirth couplings) and the assembly is secured through a pre-stretched tie-rod. This rotor stacked configuration is not typical for the most of the industrial centrifugal compressors (a solid shaft with shrink fitted impellers is the common solution, as anticipated) but it is allowed by API standards [1], and it is referenced in Turbomachinery technical literature [2]. The rotordynamics of this special prototype is very challenging since it deals with a seven piece stacked rotor running supercritical. An extensive validation program was required in addition to careful design. This is the specific subject of the present paper which will cover the main following items: validation of the “rotor alone” rotordynamic modelization through comparison with the relevant ping test results, selection of special high speed journal bearings, and overview of the low and high speed balancing process. All these steps together finally allowed the author’s company to fully demonstrate the soundness of this stacked rotor technology for application in High Pressure Ratio Compression service.