Friction-reduced hydrodynamic sliding linear bearing with diminished inclination of tilting to increase the sliding velocity by means of optimal design of the sliding surfaces

• Applicant: Professor Dr.-Ing. Martin Dix, since 4/2021
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering ; Engineering Design, Machine Elements, Product Development ; Production Systems, Operations Management, Quality Management and Factory Planning
• Term: from 2016 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 285064832

• Final Report Year: 2025

Final Report Abstract

Modeling the hydrodynamic effect of plain bearings using the Reynolds differential equation is state of the art. However, the established numerical methods based on these equations reach their limits in terms of modeling quality when calculating the system-inherent transient floating of the linear guides of machine tools with their typical reversing and inconstant movements. In the solution approach of funding period 1, various calculation approaches were combined to capture the real boundary conditions. However, only with the implementation of two correction factors, which were determined with the help of experimental parameter identification, a relatively accurate prediction of the floating was possible. However, even small changes in the usually constant test conditions and cycles required a new identification of the above-mentioned factors. In particular, the change in the lubrication condition at the start of the stroke changes the behavior. Consequently, the aim of funding period 2 was to develop a pressure measurement system in order to avoid permanent parameter adjustment. It consists of small holes in the guideway, which are positioned in a line at right angles to the feed direction and lead to an oil reservoir inside the rail, where a pressure sensor is placed to measure the very low hydrodynamic pressure in the lubrication gap. In particular, the flow behaviour of the oil in the very small holes was simulated and their diameter optimized. For experimental tests, the existing test stand was equipped on one side with a slide bar and guiding rail, each made of Plexiglas. The guiding rail was provided with seven pressure-measuring positions. After successful static and dynamic verification, the preferred variant was fitted with a steel guiding rail at seven points and tested again. Each measuring point consists of nine boreholes with which an average pressure value can be measured. The measurements show good qualitative agreement between the seven measurement curves, which react very sensitively to changes in the lubrication gap. In future, the pressure measurement could be used to draw conclusions about the actual lubrication conditions.

Publications

• Geometrische Gestaltung hydrodynamischer Gleitflächen für Geschwindigkeiten bis 100 m/min – Berechnung und Experiment. Gleit- und Wälzlagerungen 2017, 367-372. VDI Verlag.
  Zhang, Y.; Gläser, M.; Wittstock, V. & Putz, M.
  
• Anwendung der Reynolds’schen Differentialgleichung zur Simulation des instabilen Aufschwimmverhaltens der hydrodynamischen Linearführungen bei hohen Geschwindigkeiten. 59. Tribologie- Fachtagung, 24.-26. September 2018, Göttingen.
  Zhang, Y., Wittstock, V., Regel, J. & Putz, M.
  
• Real Time Simulation Using Reynold’s Equation for Instable Floating of Hydrodynamic Guides at High Speed. Advances in Production Research, 500-509. Springer International Publishing.
  Zhang, Yingying; Wittstock, Volker; Regel, Joachim & Putz, Matthias
  
• SIMULATION FOR INSTABLE FLOATING OF HYDRODYNAMIC GUIDES DURING ACCELERATION AND AT CONSTANT VELOCITY. Journal of Machine Engineering, 18(3), 5–15.
  ZHANG, Yingying; WITTSTOCK, Volker & PUTZ, Matthias
  
• Modellierung des Aufschwimmverhaltens hydrodynamischer Linearführungen bei konstanter Geschwindigkeit. Forschung im Ingenieurwesen, 83(2), 267-272.
  Zhang, Yingying; Wittstock, Volker & Putz, Matthias
  
• Development of Pressure Sensors Integration Method to Measure Oil Film Pressure for Hydrodynamic Linear Guides. Lecture Notes in Production Engineering, 276-287. Springer International Publishing.
  Ibrar, B.; Wittstock, V.; Regel, J. & Dix, M.
  
• Experimentelle Verifizierung des hydrodynamischen Drucks in Gleitführungen zur Kontrolle der Schmierung bei hohen Geschwindigkeiten. Gleit- und Wälzlagerungen 2023, 211-220. VDI Verlag.
  Wittstock, V.; Ibrar, B. & Dix, M.
  
• Integration and Verification of Miniature Fluid Film Pressure Sensors in Hydrodynamic Linear Guides. Journal of Machine Engineering.
  Ibrar, Burhan; Wittstock, Volker; Regel, Joachim & Dix, Martin
  
• Influence of Lubrication Cycle Parameters on Hydrodynamic Linear Guides through Simultaneous Monitoring of Oil Film Pressure and Floating Heights. Lubricants, 12(8), 287.
  Ibrar, Burhan; Wittstock, Volker; Regel, Joachim & Dix, Martin
  
• Beitrag zur Modellierung des Aufschwimmverhaltens hydrodynamischer Gleitführungen. Ph.D. Thesis, TU Chemnitz, Verlag Wissenschaftliche Scripten, Auerbach, Germany, 2025.
  Zhang, Yinying
  
• Highly Sensitive Measuring System for Rail Width and Point-Related Hydrodynamic Pressure in Linear Sliding Guideways of Machine Tools. Machines 2026, 14, 609.
  Wittstock, Volker; Ibrar, Burhan & Dix, Martin