Development of a Two-Speed Planetary Gearbox for an Oceanographic Winch in Arctic Conditions
Kaipainen, Paulus (2017)
2017
Konetekniikka
Teknisten tieteiden tiedekunta - Faculty of Engineering Sciences
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Hyväksymispäivämäärä
2017-12-07
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201711222222
https://urn.fi/URN:NBN:fi:tty-201711222222
Tiivistelmä
Arctic conditions are challenging on any machine component. Issues to take into account are, for example, ductile-to-brittle transition of materials, increased lubricant viscosity, ice accretion and strong temperature gradient. A growing number of research vessels, cargo vessels and vessels seeking natural re-sources are operating in the Arctic. The winches on the decks of those ships must withstand the harsh conditions. The purpose of this thesis is to develop a planetary gearbox that is used in a deck winch of a research vessel and satisfies the requirements set by the conditions and the winch. Among the conditions, the most significant requirements are dual speed, electric speed shift, heave compensation and integration of the control logic on the gearbox.
Theoretical examination focuses on the micro- and macro level phenomena caused by low temperature predominantly from the viewpoint of the embrittlement of alloyed steels. The objective was to understand the phenomenon and to find steel grades that are suitable for gear wheels and shafts and have their ductile-to-brittle transition temperature below the design temperature limit of -55 °C. Choosing the correct material for the cast housing is also important since many cast iron grades become extremely brittle due to their high carbon con-tent. Equations were derived for the loads induced by the winch. Based on the resulting mathematical model, the main components of the gearbox were dimensioned. The behavior of the lubricant, cooling of the gearbox, control and electric speed shift were discussed theoretically while keeping the practice in mind. In the practical design work, the results of the theoretical investigation were applied.
The main theoretical result of this thesis is profound research of the ductile-to-brittle transition phenomenon. Based on it, the suitability of almost any case hardening steel grade may be assessed. The most important practical outcome of this thesis is a completely designed two-speed planetary gearbox with a novel, integrated electromagnetic shift mechanism. Another important outcome is a generic graphical calculation program to comprehensively analyze basically any winch. The program includes the dynamic aspects of a heave compensation system and uses over 40 freely selectable input variables. A prototype of the developed concept will be manufactured and tested to verify the conformity of the gearbox. That is not, however, part of this thesis.
Theoretical examination focuses on the micro- and macro level phenomena caused by low temperature predominantly from the viewpoint of the embrittlement of alloyed steels. The objective was to understand the phenomenon and to find steel grades that are suitable for gear wheels and shafts and have their ductile-to-brittle transition temperature below the design temperature limit of -55 °C. Choosing the correct material for the cast housing is also important since many cast iron grades become extremely brittle due to their high carbon con-tent. Equations were derived for the loads induced by the winch. Based on the resulting mathematical model, the main components of the gearbox were dimensioned. The behavior of the lubricant, cooling of the gearbox, control and electric speed shift were discussed theoretically while keeping the practice in mind. In the practical design work, the results of the theoretical investigation were applied.
The main theoretical result of this thesis is profound research of the ductile-to-brittle transition phenomenon. Based on it, the suitability of almost any case hardening steel grade may be assessed. The most important practical outcome of this thesis is a completely designed two-speed planetary gearbox with a novel, integrated electromagnetic shift mechanism. Another important outcome is a generic graphical calculation program to comprehensively analyze basically any winch. The program includes the dynamic aspects of a heave compensation system and uses over 40 freely selectable input variables. A prototype of the developed concept will be manufactured and tested to verify the conformity of the gearbox. That is not, however, part of this thesis.