Assessing the Maximum Permissible Friction Coefficient in Bolted Joints of the ITER Blanket Modules

The standard method for determining the torque in tightening and unscrewing connections was used to calculate the maximum permissible friction coefficients in threads of three bolt connections of the ITER blanket modules (M24?3, M52?4, M64?4) at different values of the proportionality coefficient (0.45...1. 00). Influence of the friction coefficient at the bolt head supporting end was taken into account. Existing equations for assessing the torque in tightening and unscrewing the bolted connections were systematized. Equations were obtained to determine the friction coefficient in a thread taking into account the friction force at the end of the bolt for a nut with metric and self-locking threads of the SpiraLock system. Significant excess in the established maximum permissible torque in tightening and unscrewing ITER blanket modules on the robot manipulator was revealed at standard values of the thread friction coefficients (0.11...0.23) and at the ends (0.07...0.12) for the M52x4 bolts and M64?4 bolts with the solid lubricant coating/material based on molybdenum disulfide in the threads and on the bolt head supporting end. Obtained values of the maximum permissible friction coefficients in the thread make it possible to conclude that it is necessary to reduce the maximum force in tightening the M52?4 and M64?4 bolted joints, and/or increase the maximum permissible torque on the robot manipulator.

References

[1] Berezin S.Ya., Karpov A.R. Energy principle evaluation locking properties of screw joints with wavy surface one of the parts. Sborka v mashinostroenii, priborostroenii [Assembling in Mechanical Engineering and Instrument-Making], 2016, no. 10, pp. 31–35. (In Russ.).

[2] Berezin S.Ya. History of self-locking threads. Sborka v mashinostroenii, priborostroenii [Assembling in Mechanical Engineering and Instrument-Making], 2018, no. 4, pp. 186–191. (In Russ.).

[3] Lozovan A.A., Betsofen S.Y., Lyakhovetskiy M.A. et al. Study of the ion assisted sputtering process parameters influence on the structure and morphology of TiPb coatings. J. Phys.: Conf. Ser., 2019, vol. 1396, art. 012029, doi: https://doi.org/10.1088/1742-6596/1396/1/012029

[4] Lozovan A.A., Betsofen S.Y., Savushkina S.V. et al. Influence of sputtering geometry and conditions on the structure and properties of the TiN–Pb solid lubricating coatings fabricated by magnetron co-sputtering of two separate targets. Russ. Metall., 2022, vol. 2022, no. 11, pp. 1441–1448, doi: https://doi.org/10.1134/S0036029522110155

[5] Belikov A.I., Syomochkin A.I., Phyo K.Z. et al. Magnetron deposition of MoS2 ultrathin films in conditions of magnetic field. Proc. SPIE, 2021, vol. 121571F, doi: https://doi.org/10.1117/12.2624496

[6] Belikov A.I., Phyo K.Z., Guk M.M. AFM study of the MoS2 thin films deposited by magnetron sputtering growth initial stage. Proc. SPIE, 2021, vol. 121571G, doi: https://doi.org/10.1117/12.2622386

[7] Torskaya E.V., Morozov A.V., Malyshev V.N. et al. Processing and tribological properties of PEO coatings on AlZn5.5MgCu aluminium alloy with incorporated Al-Cu-Fe quasicrystals. Ceramics, 2023, vol. 6, no. 2, pp. 858–871, doi: https://doi.org/10.3390/ceramics6020049

[8] Toma F.L., Meyer A., Kunze O. et al. Microstructural characterization and oscillating sliding wear investigations of the aqueous suspension sprayed HVOF WC-12Co coatings. J. Therm. Spray Tech., 2023, vol. 32, no. 2, pp. 456–472, doi: https://doi.org/10.1007/s11666-023-01529-x

[9] Torkashvand K., Gupta M., Björklund S. et al. Tribological performance of thin HVAF-sprayed WC-CoCr coatings fabricated employing fine powder feedstock. J. Therm. Spray Tech., 2023, vol. 32, no. 4, pp. 1033–1046, doi: https://doi.org/10.1007/s11666-022-01506-w

[10] Tesa T., Musalek R., Medricky J. et al. Development of suspension plasma sprayed alumina coatings with high enthalpy plasma torch. Surf. Coat. Technol., 2017, vol. 325, pp. 277–288, doi: https://doi.org/10.1016/j.surfcoat.2017.06.039

[11] Kononenko A.S., Ignatkin I.Y., Drozdov A.V. Recovering a reducing-gear shaft neck by reinforced-bush adhesion. Polym. Sci. Ser. D, 2022, vol. 15, no. 2, pp. 137–142, doi: https://doi.org/10.1134/S1995421222020113

[12] Yang Y., Luan H., Guo S. et al. Tribological behaviors of Inconel 718–tungsten carbide friction pair with sulfur additive lubrication. Metals, 2022, vol. 12, no. 11, art. 1841, doi: https://doi.org/10.3390/met12111841

[13] Morozov A.V. Experimental estimate of tribological characteristics of epilam-coated materials that operate in threaded joints under dry friction. Trenie i iznos, 2014, vol. 35, no. 3, pp. 236–243. (In Russ.). (Eng. version: J. Frict. Wear, 2014, vol. 35, no. 3, pp. 170–176, doi: https://doi.org/10.3103/S106836661403009X)

[14] Dragunov Yu.G., Leshukov A.Yu., Strebkov Yu.S. et al. Development of design, manufacture and experimental proof of operational availability of ITER blanket components. VANT. Ser. Termoyadernyy sintez [Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion], 2016, vol. 39, no. 4, pp. 13–26, doi: https://doi.org/10.21517/0202-3822-2016-39-2-29-43 (in Russ.).

[15] Sviridenko M.N., Leshukov A.Yu., Tomilov S.N. et al. Optimization of mechanical attachment system of ITER first wall. VANT. Ser. Termoyadernyy sintez [Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion], 2020, vol. 43, no. 4, pp. 15–26, doi: https://doi.org/10.21517/0202-3822-2020-43-4-15-26 (in Russ.).

[16] Sviridenko M.N., Leshukov A.Yu., Razmerov A.V. et al. Mechanical attachment system of the first wall panels in ITER blanket. VANT. Ser. Termoyadernyy sintez [Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion], 2016, vol. 39, no. 2, pp. 29–43, doi: https://doi.org/10.21517/0202-3822-2016-39-2-29-43 (in Russ.).

[17] Khripunov B.I., Koidan V.S., Ryazanov A.I. et al. Impact of deuterium plasma flux on fusion reactor material: radiation damage, surface modification, erosion. . VANT. Ser. Termoyadernyy sintez [Problems of Atomic Science and Technology, Ser. Thermonuclear Fusion], 2020, vol. 1, no. 43, pp. 46–54, doi: https://doi.org/10.21517/0202-3822-2020-43-1-46-54 (in Russ.).

[18] Tremsin A.S., Yau T.Y., Kockelmann W. Non-destructive examination of loads in regular and self-locking Spiralock® threads through energy-resolved neutron imaging. Strain, 2016, vol. 52, no. 6, pp. 548–558, doi: https://doi.org/10.1111/str.12201

[19] Spiralock®. stanleyengineeredfastening.com: website. URL: (https://www.stanleyengineeredfastening.com/brands/optia/spiralock (accessed: 10.04.2023).

[20] Emuge. SelfLock. Intergrated thread locking tools. URL: https://www.emuge.com/sites/default/files/EMUGE_SELF-LOCK-v7.pdf (accessed: 10.04.2023).

[21] Boettcher A. Ramp breaks common thread of fastener failures. machinedesign.com: website. URL: https://www.machinedesign.com/archive/article/21816697/ramp-breaks-common-thread-of-fastener-failures (accessed: 10.04.2023).

[22] Brans P. What will the blanket teach us? iter.org: website. URL: https://www.iter.org/newsline/-/3323 (accessed: 10.04.2023).

[23] Vaughan Thompson, Russell Eaton, Rene Raffray et al. Properties of low friction anti-seize coatings for fusion applications. Fusion Eng. Des., 2019, vol. 146, Part A, pp. 345–348, doi: https://doi.org/10.1016/j.fusengdes.2018.12.064

[24] Choi C.H., Shi S., Yokoyama T. et al. Concept of operation of the remote handling system for the ITER vacuum vessel pressure suppression system. Fusion Eng. Des., 2021, vol. 173, art. 112875, doi: https://doi.org/10.1016/j.fusengdes.2021.112875

[25] Ryakhovskiy O.A., Syromyatnikov V.S. The experimental determination of the coefficients of friction in bolted joints. Izvestiya vysshikh uchebnykh zavedeniy. Mashinostroenie [BMSTU Journal of Mechanical Engineering], 2016, no. 10, pp. 18–25, doi: https://doi.org/10.18698/0536-1044-2016-10-18-25 (in Russ.).

[26] Kasparova M., Zahalka S., Houdkova F. Evaluation of the bond strength of the thermally sprayed coatings. Roznov pod Radhostem, 2010.

[27] Lubrication solutions for threaded conncections. MOLYKOTE. dge-europe.com: website. URL: https://dge-europe.com/lubrication-solutions-threaded-connections/ (accessed: 22.12.2023).

[28] Nord-lock. nord-lock.com: website. URL: https://www.nord-lock.com/nord-lock/torque-guidelines (accessed: 10.04.2023).

[29] Kotov I.V. Sovershenstvovanie tekhnologii izgotovleniya vysokonagruzhennykh rezbovykh soedineniy atomnykh energoustanovok tipa BN-800, BN-1200. Disc. kand. tekh. nauk [Improvement of manufacturing technology of highly loaded threaded joints of BN-800 and BN-1200 nuclear power units. Kand. tech. sci. diss.]. Podolsk, TsNIITMASh Publ., 2015. 165 p. (In Russ.).