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0ANALYSIS OF EXPERIMENTAL TESTING OF GENERATOR DRIVE GEARBOX AT THE KAKHOVKA DEPOT OF ODESSA RAILWAY
Boryak K.
Doctor of Technical Sciences, Associate Professor Odessa State Academy of Technical Regulation and quality
Department of Metrology and Metrological Support Odessa State Academy of Technical Regulation and quality
Peretyaka N. Competitor
Department of Metrology and Metrological Support Odessa State Academy of Technical Regulation and quality
ABSTRACT
The results of experimental testing of the type EUK-160-1M gearbox included in the generator's gearbox and cardan shaft drive of the passenger car are analyzed. The threshold value of gearbox heating rate which reveals a satisfactory technical state of the mechanism is determined. It is offered to use it as a crucial parameter of diagnosing, which will reduce the time of bench testing and electricity expenditure to 6 times. Keywords: testing, gearbox, heating temperature, heating rate.
1. Introduction
According to UNSS ISO 9001: 2009 [1], an organization should inspect and measure the characteristics of its products to check whether they meet the technical requirements, in order to detect in time and remove those products that do not meet the requirements, to prevent its unintended supply to the consumer. In compliance with UNSS ISO 9003-95 [2] the status of products according to the results of inspection and testing should be marked by relevant means, which indicate products' compliance or non-compliance. Identification of the products' status according to the results of inspection and testing should be carried out regularly in agreement with the quality program and (or) documented procedures to ensure such an order in which only the products that passed all the necessary kinds of finished product inspection and its testing can be shipped.
Improving the reliability and efficiency of operation of various industries' objects throughout the required period of service is an important national economic problem. It is solved only with the help of complex diagnosing of the objects that carry the potential for the creation of an emergency case resulting in financial and even human losses. The problem of the equipment reliability is closely followed by the tasks of providing energy and environmental security [3].
2. Analysis of literary data and the formulation of the problem
In passenger sleeping cars, dining cars and service cars they set the current from the middle part of wheel axle generator drive, which is able to transmit the power of 28 kW and more. They are reliable in operation, do not load an axle hub, but have a significant drawback - the complexity of maintenance and repair, especially in case of full dismantling [4].
During the car exploitation, large dynamic loads are applied to the drive, which causes excess deformation of the parts and components, their operating life is reduced which requires their restoring during passenger cars' periodic repairs and technical servicing. There
are two types of drive repair: with replacement or without replacement of critical parts. After repairing the drive has to be tested on break stands, which must be certified, and measuring equipment should be previously examined [5].
The crucial parameter for diagnosing the technical condition of the gearbox according to the thermal method is the temperature of oil heating in the gearbox's crankcase and bearings. Gearbox's operational suitability according to the thermal method is estimated by comparing the values obtained when measuring the gearbox case's temperature in control points with normed critical value of heating temperature (<70 ° C) [6].
3. Purpose and objectives of the study
The objective of the study is to find an energy-efficient method of gearbox bench testing to reduce power consumption for testing one gearbox.
The problem to be solved is to improve the process of gearboxes' bench testing considering modern requirements for energy efficiency.
Testing of the type EUK-160-1M gearboxes is conducted in accordance with the industry requirements [7]. The mode of running, in line with which gearbox testing after repair with replacement of critical parts is carried out, consists of four stages: a 30-minute test without loading in one direction (rightwards) and the same in the opposite (leftwards) direction, then 60 minutes of test with a load of 40 kW in one direction (rightwards) and the same in the opposite (leftwards) direction. When loading smooth regulation of increase in the number of rotations of the wheel set from 0 to 900 rev / min. After each phase of testing operator measures temperature in control points of the gearbox case, and by comparing the data with the permissible values makes decision about its further operational suitability.
In the gearbox, because of the complexity of mechanical construction and a number of friction a complex thermal heating process takes place. To optimize the timing technological bench testing of generator
drive gearbox of the middle part of the axle of the passenger car's wheel set, the study of the character of case's heating temperature, determination of the phases of heating in time, to find out the rate of the case heating for different phases and dependence of heating rate on technical condition of the gearbox, we conducted experimental studies of one type of EUK-160-1M gearbox heating in mode of running on the test stand, which is operated in the production unit of the "Train depot of
Kakhovka station" branch.
of "Odessa railway" regional
4. Materials and methods of research
In April, 2014, three EUK-160-1M gearboxes which came from the repair shop for repairs quality control underwent experimental study on the certified working stand for the gearboxes with drives of the mid-die part of the passenger car's wheel pair axle (Fig. 1).
a b
Fig. 1. Stand for running gearboxes of the middle part of the passenger car's wheel set axle which is operated
in the Kakhovka station depot: a - stand, b - equipment panel
Before testing gearboxes were checked for compliance with technical specifications that were within acceptable limits. Conditions of the testing were the following: the power supply voltage - U = 380 V; power supply frequency - f = 50 Hz; electric drive power - Ned = 32 kW; the noise level in the room - Dnl = 48 dB; envoriment temperature at the beginning of the experiment Temb = 12oC.
During the tests the outside air temperature, the temperature of the crankcase and bearings were recorded. To conduct the experiment, temperature measurements were taken every 1,8 minute. Gearbox's temperature measurement was taken with the help of digital thermoelectric thermometer TT-TS016 TU UZ.48-
04850451-057-98 with temperature measurement error of ± 2°C. The results of measurements were recorded on the tape by the recorder pen.
5. Research results
Experimental results are presented in form of graphs. The highest temperature values were recorded in the point of bearings localization in the part of gearbox's output shaft, so the control point was considered crucial.
Fig. 2 demonstrates the temperature and heating rate function of the time when testing without a load with the wheelset rotation direction 'rightwards'.
a
Trials with no load
«-i cn m r- ooi^i-vo oi h m ^ n oo o
„ „ „ „ „ oi fv) fv) (N m
Time, minutes
'reducer № 1-reducer № 2 reducer № 3.........polinomial
b
Fig. 2. Obtained results: a - gearbox's heating temperature; b - gearbox's heating rate
The graph (Fig. 2a) shows that when tested without a load the dependence of temperature on time does not have linear character and is authentically described with a second-degree polynomial. Fluctuations in the rate of temperature change are of aperiodic character related to the heat exchange persistence and heterogeneity of technical condition of parts and components of complex mechanical system. The maximum heating temperature increase accounts for a range of 4 to 25 minutes. The absolute basic temperature increase of gearbox was ATI = 12oC, AT2 = 9oC, AT3 = 8,5oC.
The graph (Fig. 2b) shows that the temperature change rate ranged from 0,1 to 1,1 ° C / min. Heating speed increases since the 5th minute and decreases in a suitable gearbox on the 10th minute. The maximum heating rate of the unsuitable gearbox is the 16th minute, then temperature rate increase stops.
The value of heating rate Rhs was calculated using the formula:
Rhs —
AT.
a ch
AT
(1)
where ATach - an absolute chain increase of control temperature measurements, °C;
At - the time interval between control measurements of gearbox's temperature, min.
When calculating, the ambient temperature increase by 2 degrees due to its insignificance was not taken into account.
Fig. 3 demonstrates functional dependence of temperature and heating rate on the time when tested with a load of wheelset rotation direction "rightwards". When running without a load in the opposite direction of the "leftwards" rotation, temperature dependence on time has linear character, therefore, the graph is not presented here.
u
b
Fig. 3. Obtained results: a - gearbox's heating temperature; b - gearbox's heating rate
The graph (Fig. 3 a) shows that the temperature of the gearbox №1 has exceeded the maximum heating temperature of 70 ° C. Testing of this gearbox was stopped. Gearboxes № 2 and № 3 underwent further testing with a load of leftwards direction of wheelset rotation. At this stage of testing, the temperature was increasing linearly and did not exceed the maximum norm.
When tested under load maximum heating temperature increase falls on 7th - 39th minutes. The absolute basic temperature increase of each gearbox was ATI = 49,9 °C, AT2 = 27,9 ° C and AT3 = 42,1 ° C.
The graph (Fig. 3b) shows that the rate of gearbox's temperature change in satisfactory condition was to 1,1 ° C / min. Since the 24th minute temperature speed increase stops. Heating speed of unsuitable gearbox was 1,6 ° C / min. The maximum was observed on the 21st minute.
Three phases of case's heating can be found on the graphs (Fig. 2a and 3 a): before the 5th minute there is the first phase of irregular heating, the second phase -since the 6th to 32nd minute corresponds with regular heating, and the third phase starting with the 32nd minute is heating stabilization. The graphs (Fig. 2b and
3b) show that intensive increase of heating rate takes place at the second phase (regular heating), so it is clear that it is this phase suitable for diagnosing. The authors suggest diagnosing the technical condition of the gearbox according to the thermal method with additional option - according to the value of gearbox's case heating rate in intermediate control points of the experiment time, on the 20th and 30th minutes. If the value of gearbox's case heating rate in control points exceeds 1,1 ° C / min., further tests stop. This will enable to reduce the testing time to 6 times if the gearbox is not suitable for further use.
It was found out experimentally, that the temperature values of technically suitable gearbox on a 20th minute of testing under load should not exceed 50 ° C, and the value of heating rate in the same control point should not exceed 1,1 ° C / min.
6. Discussion of results
1. The highest temperature values were recorded in the place of bearings location in the gearbox output shaft.
2. Dependence of temperature change over a period of time is not linear and is authentically described with a second-degree polynomial. Fluctuations of the value of temperature change rate are of an aperiodic character. The values of temperature change rate over a period of time in case of technically suitable gearboxes can reach 1,1 ° C / min, which is offered to be considered crucial for the suitable gearbox.
3. Among the three phases the most significant fluctuations of the values of heating rate (up to 1,6 ° C / min) were recorded at the second phase (from the12th to 30th minutes). Therefore, when thermal method of nondestructive gearbox testing diagnostics should be carried out at the phase of regular heating.
4. A further perspective is seen in improving existing method of gearbox bench testing, based on thermal method of diagnosing of technical condition, on ac-
count of the introduction of additional diagnostic parameter - the rate of gearbox's case heating rate, that would significantly (up to 6 times) reduce overall technological time and save electrical energy to power the test stand.
7. Conclusions
Scientific innovation conducted by the authors of studies seen in the improved method of bench testing of mechanical components, which differs from the current introduction of additional diagnostic parameters -temperature gradient that allows significantly (6 times) to reduce the technological time needed expert to determine the technical condition of the mechanical unit. For example, generator gear drive from the middle of the wheelset axles of passenger cars may reduce the time of testing from 180 to 24 minutes.
References
1. DSTU ISO 9001: 2009. Quality Management Systems. Requirements.
2. DSTU ISO 9003-95. Model for quality assurance in final inspection and test
3. Abramova, E. V.; Diagnostic the thermal control system: an integrated approach, Technical diagnostics and non-destructive testing, No. 2 (2011) 34-39.
4. Bykov, B. V.: Construction and repair of drive undercar generators, Route, Moscow, 2005.
5. Reshetov, D. N. (ed.): Machinery and stands for testing of details, Mechanical Engineering, Moscow, 1979.
6. DSTU 2796-94 (GOST 29285-95). Mechanical actuators. Test methods.
7. The State Administration of Railway of Transport of Ukraine. Instruction on repair reducers -the cardan drives passenger carriages, The State Administration of Railway of Transport of Ukraine. Ukr-zaliznytsia. The main passenger management, Kyiv, 2010.
