Wyniki wyszukiwania - BazTech

1

Stand for tests of pipes and their joints under conditions of a programmable internal pressure value and variable temperature

Boroński Dariusz, Maćkowiak Paweł, Płaczek Dominika, Kotyk Maciej

Journal of Machine Construction and Maintenance - Problemy Eksploatacji

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2019

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no. 1

85--92

EN

Producers of hydraulic elements introduce new structural solutions and new materials. The aim of these activities is to increase the quality, reduce the costs, and shorten the assembly time of hydraulic elements. Consistently, with the requirements provided by the standards and technical specifications, the manufactured elements need to undergo tests of the resistance to variable temperatures and internal pressure loads. To reduce the time of tests and provide safety, the pressure applied to tested elements is higher than the load that they are exposed to while in regular operation. Additionally, the increased frequency of temperature changes is applied for the fluid, which flows through the system as well as a difference between the temperature of warm and cold fluid higher than in regular operation. Such tests are supposed to confirm the reliability of the tested structural solutions used in pipes and fittings and reveal problems connected with the impact of different types of materials and their combinations on hydraulic element systems. Commonly used tests stands are characterized by a large size and high energy needs. The aim of this study is to present the design and operation of a simple stand for tests of hydraulic elements and specimens whose internal surfaces are affected by the flow of fluid with higher pressures and variable temperatures. The analysed system is featured by smaller size, higher energy efficiency, and it needs less fluid for tests. Moreover, it enables the control of the test parameters in compliance with safety requirements.

PL

Producenci elementów hydraulicznych wprowadzają nowe rozwiązania konstrukcyjne i materiały. Celem tych działań jest zwiększenie jakości, zmniejszenie kosztów oraz skrócenie czasu montażu elementów hydraulicznych. Zgodnie z zaleceniami norm oraz wymaganymi aprobatami technicznymi produkowane elementy muszą przejść badania odporności na zmienne temperatury i obciążenia wewnętrznym ciśnieniem. W celu skrócenia czasu trwania testów i zapewnienia bezpieczeństwa elementy poddawane są obciążeniu większym ciśnieniem niż podczas normalnej eksploatacji. Dodatkowo stosuje się zwiększoną częstotliwość zmian temperatury przepływającej cieczy przez układ oraz większą różnicę pomiędzy temperaturą cieczy ciepłej i zimnej, niż ma to miejsce w docelowych instalacjach. Tak prowadzone badania mają na celu potwierdzić niezawodność stosowanych rozwiązań konstrukcyjnych złączek oraz problemy związane z zastosowaniem różnych typów materiałów i ich kombinacji na elementy układów hydraulicznych. Obecnie stosowane stanowiska badawcze posiadają znaczne gabaryty i charakteryzują się dużym zużyciem energii. Celem pracy jest przedstawienie budowy i sposobu działania prostego w budowie stanowiska do badań elementów hydraulicznych i próbek poddawanych od wewnętrznej strony przepływowi cieczy o podwyższonym ciśnieniu i zmiennej temperaturze. Przedstawiony układ cechuje się mniejszymi gabarytami, mniejszym zapotrzebowaniem na energię i ciecz wykorzystywaną podczas badania. Ponadto umożliwia kontrolę parametrów badania przy zachowaniu wymogów bezpieczeństwa.

2

Problems of the starting and operating of hydraulic components and systems in low ambient temperature (Part V) methods ensuring correct start-up of hydraulic components of ship’s onboard devices in low ambient temperatures

Jasiński R.

Polish Maritime Research

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2017

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nr 4

47--56

EN

A large number of hydraulic devices and systems are started in low ambient temperatures. A good example of such a device is the hoisting winch on the ship. Starting hydraulic drive units in thermal shock conditions (rapid supply of hot oil to the cold unit) may lead to incorrect operation of the actuating system, for instance, due to the loss of clearance between cooperating elements. The article presents methods to prevent the disappearance of effective clearance in a hydraulic motor started in thermal shock conditions. For this reason, the structure of the hydraulic satellite motor was complemented by elements creating special channels through which hot oil could flow and additionally heat fixed parts of the motor. This solution ensures faster heating of motor housing, thus decreasing the temperature difference between the housing and the satellites during motor start-up in thermal shock conditions.

3

Problems of the starting and operating of hydraulic components and systems in low ambient temperature (Part IV) Modelling the heating process and determining the serviceability of hydraulic components during the starting-up in low ambient temperature

Jasiński R.

Polish Maritime Research

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2017

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nr 3

45--57

EN

Designers of hydraulically driven machines and devices are obliged to ensure during design process their high service life with taking into account their operational conditions. Some of the machines may be started in low ambient temperature and even in thermal shock conditions (due to delivering hot working medium to cold components). In order to put such devices into operation appropriate investigations, including experimental ones - usually very expensive and time-consuming, are carried out. For this reason numerical calculations can be used to determine serviceability of a hydraulic component or system operating in thermal shock conditions. Application of numerical calculation methods is much less expensive in comparison to experimental ones. This paper presents a numerical calculation method which makes it possible to solve issues of heat exchange in elements of investigated hydraulic components by using finite elements method. For performing the simulations the following data are necessary: ambient temperature, oil temperature, heat transfer coefficient between oil and surfaces of elements, as well as areas of surfaces being in contact with oil. By means of computer simulation method values of clearance between cooperating elements as well as ranges of parameters of correct and incorrect operation of hydraulic components have been determined. In this paper results of computer simulation of some experimentally tested hydraulic components such as axial piston pump and proportional spool valve, are presented. The computer simulation results were compared with the experimental ones and high conformity was obtained.

4

Badania doświadczalne zminiaturyzowanych elementów hydraulicznych

Kudźma Z., Stosiak M.

Napędy i Sterowanie

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2016

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R. 18, nr 10

112--118

PL

W artykule przedstawiono wybrane przykłady zminiaturyzowanych elementów hydraulicznych. Zaprezentowano wyniki prac własnych dotyczących przepływów w mikroelementach hydraulicznych (mikrozaworze wzniosowym, mikroprzewodzie hydraulicznym) oraz wydzielenia obszaru pracy stabilnej mikrozaworu hydraulicznego. Zwrócono uwagę na hałaśliwość pracy układów mikrohydraulicznych, poddając, jako przykład, analizie mikrozasilacz hydrauliczny.

EN

In the paper some selected examples of miniaturized hydraulic components were presented. Some results of tests of flow in hydraulic microcomponents (lift microvalve, hydraulic micropipe) and creating of stable work of hydraulic microvalve were discussed. Special attention was focused on noise problem of microhydraulic systems. This problem was considered in example of microhydraulic power unit.

5

Analiza produktów i usług prezentowanych na targach branżowych

Partyka M. A., Piłot T., Deptuła A.

Hydraulika i Pneumatyka

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2011

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nr 5

22-27

6

Modelowanie zjawisk przepływowych w blokach zaworowych górniczych obudów zmechanizowanych

Rosikowski P.

Hydraulika i Pneumatyka

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2010

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nr 6

22-25

7

Condition-based preventive maintenance of machine tools

Neugebauer R., Fischer J.

Journal of Machine Engineering

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2009

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Vol. 9, No. 3

64--76

EN

Machine tools are expected to be highly available. Unintended failure incurs high costs for repairs and through production losses. Maintenance is a major cost factor and is still mostly reactive today, as a result of failures. Maintenance plans by manufacturers that require preventive maintenance based on running hours are often not implemented consistently. It would be ideal to perform condition-dependent preventive maintenance of the most critical and cost-intensive assemblies of a machine tool. This would make it possible to move repair times into non-productive periods and to procure any spare parts at the right time. Eventually, this would lead to cost savings. This article describes the design of a condition monitoring system for machine tools and shows ways of monitoring the most critical machine tool assemblies.