IMPROVING DYNAMIC REGIME OF ROLLING FOR INCREASING DURABILITY OF BALL-ROLLING MILL ROLLS

One  of  the  important  reasons  for  the  downtime  of  ball  rolling  mills  is  replacement  of  rolls  due  to  their  wear  and  tear.  The  degree  and  zones  of  critical  wear  of  ball  rolling  rolls  are  investigated  in  the  article, where the greatest wear is observed over the flanges in zone of billet  capture.  Conditions  necessary  to  capture  the  blank  and  to  perform  rolling  process  are  analytically  determined.  Variable  frequency  method  of  roll  rotations  is  proposed  as  a  progressive  technology  for  blank supply. The results of tests for its variations in accordance with  linear  and  quadratic  law  are  presented.  Known  formulas  determining  average  strain  rate  at  rolls  rotational  speed  change  are  converted  for  linear and quadratic dependences. Experimental studies have been carried  out  in  conditions  of  EVRAZ  Nizhnetagilsky  Metallurgical  Plant  ball rolling mills during rolling of 60mm ball made of Sh-3G steel. Experiments  were  performed  for  given  parameters  of  manual  change  in  rolls rotation speed at blank capture by rollers. The results have shown  a  significant  effect  of  change  in  rotational  speed  on  average  specific  pressure during blank capture. Evaluation of torque-time and average  contact  pressure  for  calculated  and  experimental  data  are  presented.  Empirical characteristics are also described at variable rotational speed  of rolls according to linear and quadratic law. Acceptable convergence  of results of calculated and empirical characteristics is determined. Engineering solution has been proposed for that task. It consists in installation of a thyristor converter. This solution allows reduction of rolls  speed before blank capture. Also, this solution will increase frequency  to  the  nominal  value  according  to  the  given  law  after  blank  capture.  As an obtained result, there is uniform distribution of average contact  pressure over the entire length of the roll under different operating conditions  of  mill  in  automatic  mode. Application  of  this  technique  will  reduce wear degree of the rolling tool. At the same time, productivity  of ball rolling mill will be maintained. Rolls consumption and number  of rolls change will decrease due to rolls wear.

screw gauge, flange, blank capture, blank rotation condition, rolling force, mean contact pressure, speed, linear law, square law

1. Kotenok V.I. Razvitie teorii formoobrazovaniya profilei v vintovykh kalibrakh i sozdanie vysokoeffektivnykh protsessov i oborudova­ niya dlya prokatki detalei mashin: Avtoref. dis... doktora tekh. nauk [Development of theory of profiles forming in helical roll passes and creation of high effective processes and equipment for rolling of machines parts: Extended Abstract of Dr. Sci. Diss.]. Moscow, 2005, 37 p. (In Russ.).

2. Artes A.E., Tret’yukhin V.V. Enhancement of grinding balls production. Quality and innovations. Kompetentnost’. 2014, no. 3 (114), pp. 50–53. (In Russ.).

3. Skoblo T.S., Avtukhov A.K., Klimanchuk V.V. Causes and characteristics of break-down of hot rolling mills rolls. Metallurgiya ma­ shinostroeniya. 2014, no. 3, pp. 14–17.

4. Teterin P.K. Teoriya poperechnoi i vintovoi prokatki [Theory of cross and screw rolling]. Moscow: Metallurgiya, 1983, 270 p. (In Russ.).

5. Bystrov V.A., D’yakov P.K., Umanets A.G. Operating conditions and wear of hot metal mill rolls. Izvestiya VUZov. Chernaya metallurgiya = Izvestiya. Ferrous Metallurgy. 2014, no. 5, pp. 24–29. (In Russ.).

6. Sinnave M. New grades of mill rollers and development of their production . Stal’. 2003, no. 7, pp. 48–52. (In Russ.).

7. Romantsev B.A., Aleshchenko A.S., Tsyutsyura V.Yu., Lube I.I. Features of wear of working rolls of TPA 159-426 piercing mill at rolling continuous cast billets of large diameter. Proizvodstvo prokata. 2016, no 6, pp. 20–27. (In Russ.).

8. Romantsev B.A., Aleshchenko A.S., Tsyutsyura V.Yu., Tyshchuk I.N., Lube I.I. Features of piercing mill TPA 50-200 working roll wear during rolling continuously-cast and hot-rolled billets. Metallurgist. 2017, no. 9-10, pp. 1062–1069.

9. Stan CKBMM 44 dlya prokatki sharov 40­80. Tekhnicheskii proekt [TSKBMM 44 mill for rolling the balls 40-80. Technical project] Moscow: TsNIITMASh, 1955. (In Russ.).

10. Peretyat’ko V.N., Klimov A.S., Filippova M.V. Calibration of rolls of a ball-rolling mill. Part 1. Izvestiya VUZov. Chernaya metallurgiya = Izvestiya. Ferrous Metallurgy. 2013, no. 4, pp. 27–30. (In Russ.).

11. Filippova M.V., Smetanin S.V., Peretyat’ko V.N. Computer modeling of rolling balls in screw gage. In: Modelirovanie i naukoemkie informatsionnye tekhnologii v tekhnicheskikh i sotsial’no­-ekonomicheskikh sistemakh. Trudy IV Vserossiiskoi nauchno­prakticheskoi konferentsii s mezhdunarodnym uchastiem [Modeling and high-tech information technologies in technical and socio-economic systems. Proceedings of the 4th All-Russian Sci. and Pract. Conf. with Int. Participation]. Novokuznetsk: izd. SibGIU, 2016, pp. 290–294. (In Russ.).

12. Filippova M.V., Peretyat’ko V.N., Smetanin S.V. Stresses and strains during rolling of the ball. Izvestiya VUZov. Chernaya metallurgiya = Izvestiya. Ferrous Metallurgy. 2016, no. 8, pp. 587–588. (In Russ.).

13. Tselikov A.I., Barbarich M.V. Spetsial’nye prokatnye stany [Special rolling mills] Moscow: Metallurgiya, 1971, 336 p. (In Russ.).

14. Tselikov A.I. Teoriya rascheta usilii v prokatnykh stanakh [Theory of efforts calculation for rolling mills] Moscow: Metallurgiya, 1962, 496 p. (In Russ.).

15. Grudeev A.P. Vneshnee trenie pri prokatke [External friction during rolling]. Moscow: Metallurgiya, 1973, 228 p. (In Russ.).

16. Gulyaev Yu.G., Shifrin E.I., Lube I.I., Garmashev D.Yu., Nikolaenko Yu.N. Geometry of the deforming region in rotary-rolling mills. Steel in Translation. 2013, vol. 43, no. 11, pp. 758–761.

17. Krasnevskii S.M., Makushok E.M., Shchukin V.Ya. Razrushenie metallov pri plasticheskoi deformatsii [Metals fracture by plastic deformation] Minsk: Nauka i tekhnika, 1983, 173 p. (In Russ.).

18. Novik F.S., Arsov Ya.B. Optimizatsiya protsessov tekhnologii metallov metodami planirovaniya eksperimentov [Optimization of metals processing technology by methods of experiments design] Moscow: Mashinostroenie; Sofiya: Tekhnika, 1980, 304 p. (In Russ.).

19. Belov V.I., Razgulin I.A. Estimation of average values of degree and rate of deformation using Deform 3D software at hot rolling. Mo­ delirovanie i razvitie protsessov OMD. 2014, no. 20, pp. 153–157. (In Russ.).

20. Peretyat’ko V.N., Klimov A.S., Filippova M.V., Fedorov A.A. Calib ration of rolls of a ball-rolling mill. In: Metallurgiya, tekhnologiya, upravlenie, innovatsii, kachestvo [Metallurgy, technology, management, innovations, quality]. Novokuznetsk: izd. SibGIU, 2010, pp. 258–265. (In Russ.).

21. Pater Zbigniew. Analysis of helical rolling process of balls formed from a head of a scrapper rail. Advances in Science and Technology Research Journal. 2016, vol. 10, no. 30, pp. 110–114.

22. Pater Z., Tomczak J., Bartnicki J., Lovell M.R., Menezes P.L. Experimental and numerical analysis of helical-wedge rolling process for producing steel balls. International Journal of Machine Tools and Manufacture. 2013, vol. 67, pp. 1–7.

23. Chila P., Pater Z., Tomczak J., Chila P. Numerical analysis of rolling process for producing steel balls using helical rolls. Archives of Metallurgy and Materials. 2016, vol. 61, no. 2, pp. 485–492.

24. Pater Z. FEM analysis of the multi-wedge helical rolling process for a workholding bolt. MATEC Web of Conferences. 2016, vol. 80, pp. 130, 131.