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Vasenin Valery Ivanovich, Perm National Research Polytechnic University, Associate professor, Candidate of technical sciences, Department of «Materials, technologies and machine design»
E-mail: [email protected] Bogomyagkov Aleksey Vasilievich, Assistant Sharov Konstantin Vladimirovich, Assistant
Research of the filling of a casting mould with liquid metal through step gate
Abstract: The description of laboratory step gate system is provided. Results of theoretical and experimental determination of velocity, consumption and time of the filling of a mould with aluminum alloy depending on the number of simultaneously operating feeders and their location throughout the height of the mould are set forth. A good correlation of calculated and experimental data is obtained. The possibility of application of the Bernoulli equation to the cross section of the stream with different consumption, i. e. for the gate systems with a number of feeders more than one, is proved on the example of liquid metal.
Keywords: sprue, collector, feeder, flow velocity, consumption of liquid.
Step gate systems (GS) were analyzed theoretically periments on water are apparently not sufficient to check
and experimentally (on water) in the articles [1-3] depending on the number of operating feeders and their sizes. The difference between the calculated and experimental values of velocities, consumptions and pressures was several percent. The Bernoulli equation (BE) was used in the calculations for the flow with variable consumption (and mass). Although, it was developed for the liquid flow with permanent consumption (mass) — in the absence of flow distribution to feeders [4, p. 205; 5, p. 10], i. e. for the GS with one feeder. The possibility to use the BE for the calculations of the GS with the liquid consumption ranging from maximal value to zero along the length of the collector (sludge chamber) was theoretically not proved. Why the BE works is not clear. The ex-
the proposed method of the GS calculation. Experiments on liquid metal are required. Aluminum alloy was used in the present work.
The analysis of the filling of the mould with the alloy through the step gate system was conducted in 2 stages; the top discharge of the metal from the feeders to the buckets (Fig. 1) and filling of the mould to the flooded level (Fig. 2). This was done to enhance the accuracy of the measurements. Moreover, during the top discharge from the feeders to buckets, one can define the velocity and consumption of liquid in every feeder but not a total consumption of metal in the system. This is important for the check of the method of calculation of velocity and consumption of liquid in every feeder of the GS.
Fig. 1. Gate system for the top filling of the mould with the metal from the feeders
Research of the filling of a casting mould with liquid metal through step gate
Fig. 2. Gate system for the filling of the mould with
The gate system consists of a funnel, sprue, collector, return sprue and three identical feeders I—III. The level of liquid H — distance in vertical direction from section 1-1 in the funnel till the longitudinal axis of the collector — was maintained constant: H = 375 mm. The sprue diameter was 24,1 mm; the diameter of the return sprue was 16,0 mm. The sizes of the cross section of the collector were 16,1x10,8x15,0 mm and the feeder diameter was 9,0 mm. In the figure, the section of the collector is shown in the form of a rectangle. The distance in the vertical direction from the horizontal axis of the collector to the horizontal axis of the first bottom feeder was 27,5 mm; the distance between the feeders was 75,0 mm. The liquid is discharged from top from the feeders to buckets. Aluminum-silicon alloy AS12 was used under the pouring temperature of720 °C. The sand-clay mould contained 5% of clay and 5% of water.
The internal diameter of the mould cavity (Fig. 2) was 108 mm; the height of the moulding from the longitudinal axis of the collector was 205 mm. The time of the filling of the mould with the metal was measured with points A and B, the distance between which was 180 mm. The calculation of the filling of the mould with the metal to the flood level and experiments on water are set forth in the article [6].
Table 1 presents the results of the determination of velocities of the feeders I, II, III, I and II, II and III, I and III, I—III at the top-to-bottom discharge to the bucket. Experimental values of the velocities in the feeders were lower than the calculated ones by 2,3-9,5%. At the operation of all three feeders, the total consumption in the calculation was 226,9 cm 3/s; in the experiment — 246,2 cm 3/s — the calculated consumption is lower than the experimental one by 7,8%.
the metal from bottom to top to the flooded level
Table 2 shows the results of the time of the filling of the mould with the metal to the flooded level at different number of the operating feeders. The experimental values were lower than the calculated ones by 8,0-11,1%, i. e. the velocities of discharge from the feeders were higher than the calculated ones, unlike the top-to-bottom discharge, where the experimental values of the velocities were lower than the calculated ones by 2,3-9,5%. It's not clear how to explain it. Perhaps, the discharge of liquid from the feeders and the filling of the mould to the level are different processes, although, it is implied that they are identical.
Table 1. - Characteristics of the system at the top-to-bottom discharge of the liquid metal to the mould
Operating feeders vii viii
I 1,908 1,85
II 1,678 1,62
III 1,415 1,35
I, II 1,645 1,55 1,422 1,39
II, III 1,457 1,4 1,168 1,09
I, III 1,723 1,59 1,124 1,06
I-III 1,439 1,32 1,251 1,16 0,854 0,78
but were taken from the article [7] for steel collectors and feeders of round cross-section in the experiments on water.
The Bernoulli equation for the liquid flow with constant consumption, i. e. at the operation of only one feeder in the GS, is deduced. The attempts to prove the application of the BE for the flows with variable consumption have been made for long. The review of these works is presented in the monograph of [5] 1986. After 30 years of the release of the book, there are still now advances in the solution of this seemingly simple task.
Thus, the early described theory about the calculation of L-shaped, branched, combined, step, horizontal and vertical ring systems, based on the usage of the Bernoulli equation to the cross section of the flow with different consumptions and tested in thousands of experiments on water, is also proved at the discharge of liquid metals. Apparently, one can consider the possibility of usage of the Bernoulli equation for the calculation of multi-feeding gate systems proved.
References:
1. Vasenin V. I., Bogomyagkov A. V., Sharov K. V. Investigation into a step gate system//Eastern European Scientific Journal. - 2014. - № 4. - P. 122-137.
2. Vasenin V. I., Sharov K. V. Determination of the liquid flow rates and pressures of the fluid in the step gate system//5th International conference on Science and Technology. - London: Scieuro, 2015. - P. 47-69.
3. Vasenin V. I., Bogomyagkov A. V., Sharov K. V. Investigation of the work of step gate system//Austrian Journal of Technical and Natural Sciences. - 2015. - № 9-10. - P. 21-30.
4. Chugaev R. R. Hydraulics. - M.: Bastet, 2008. - 672 p.
5. Meerovich I. G., Muchnik G. F. Hydrodynamics of collector systems. - M.: Nauka, 1986. - 144 p.
6. Vasenin V. I., Bogomyagkov A. V., Sharov K. V. Research of the mould filling with metal under the flooding level through the step gate system//4nd International conference on the political, technological, economic and social processes. - London: Scieuro, 2014. - P. 26-49.
7. Vasenin V. I., Vasenin D. V., Bogomyagkov A. V., Sharov K. V. Study of local resistances of the gate system//Herald of the Perm national research poly-technical university. Machine building, material studies. - 2012. - V. 14. -№ 2. - P. 46-53.
Table 2. - Time of the filling of the mould to the flooded level
Operating feeders T calc , C T exp Tcak Texp _100% T exp
I 15,9 14,6 8,9
I, II 94 8,7 8,0
I, III 10,0 9,3 7,5
I — III 8,0 7,2 11,1
As it is seen, the obtained results are barely different from the calculated ones. Although, the coefficients of resistance of the turn from the sprue to the collector, from the collector to the return sprue and from the return sprue to the feeder were not defined specially for the sand-clay mould and trapezoid section of the collector,
