Статті в журналах: "Surface ball"

1

Kida, Katsuyuki, Junnosuke Koga, Edson Costa Santos, and Takashi Honda. "Effect of Frequency on Fatigue Cracks of Silicon Nitride Balls under Cyclic Loads." Advanced Materials Research 217-218 (March 2011): 874–79. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.874.

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In the previous work, we found that the tensile stress occurring around the equator of the ball caused fatigue of the ball itself. Four groups of pre-cracks, whose surface lengths were 140μm, 220μm, 550μm and 700μm, were initiated on ball surfaces and the strength of these pre-cracked balls was measured. The static strengths and fatigue limits of all pre-cracked balls decreased with crack sizes. We concluded that the fatigue caused by a pre-crack located on the equator of the ball surface was important for understanding fatigue of silicon nitride balls. In the present work, carrying out fatigue tests of pre-cracked balls with 220μm cracks at three frequencies (5Hz, 20Hz and 35Hz) we found that the frequency had effect on speeds of the crack growths.

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2

Klinkov, S. V., V. F. Kosarev, A. E. Chesnokov, A. V. Smirnov, and T. M. Vidyuk. "Investigation of Influence of Input Energy during Ball Milling of Aluminum Powder." Solid State Phenomena 313 (January 2021): 143–51. http://dx.doi.org/10.4028/www.scientific.net/ssp.313.143.

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Influence of the rate at which energy is applied to aluminum powder during its ball milling is investigated. Rolling granulation is a main process due to which treated particles achieve their unique morphology and microstructure. Drastic temperature rise at rapid ball milling leads to increase in plasticity and local melting of treated powder particles that result in their adherence to the surfaces of milling balls and mill cylinder walls. Mass of aluminum powder adhered to the ball surface is proportional to the total surface area of all balls loaded in mill.

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3

Klinkov, S. V., V. F. Kosarev, A. E. Chesnokov, A. V. Smirnov, and T. M. Vidyuk. "Investigation of Influence of Input Energy during Ball Milling of Aluminum Powder." Solid State Phenomena 313 (January 2021): 143–51. http://dx.doi.org/10.4028/www.scientific.net/ssp.313.143.

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Influence of the rate at which energy is applied to aluminum powder during its ball milling is investigated. Rolling granulation is a main process due to which treated particles achieve their unique morphology and microstructure. Drastic temperature rise at rapid ball milling leads to increase in plasticity and local melting of treated powder particles that result in their adherence to the surfaces of milling balls and mill cylinder walls. Mass of aluminum powder adhered to the ball surface is proportional to the total surface area of all balls loaded in mill.

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4

Hong, Sungchan, and Takeshi Asai. "Effect of Surface Groove Structure on the Aerodynamics of Soccer Balls." Applied Sciences 10, no. 17 (August 25, 2020): 5877. http://dx.doi.org/10.3390/app10175877.

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Soccer balls have undergone dramatic changes in their surface structure that can affect their aerodynamics. The properties of the soccer ball surface such as the panel shape, panel orientation, seam characteristics, and surface roughness have a significant impact on its aerodynamics and flight trajectory. In this study, we performed wind-tunnel tests to investigate how the introduction of grooves on the surface of a soccer ball affects the flight stability and aerodynamic forces on the ball. Our results show that for soccer balls without grooves, changing the panel orientation of the ball causes a significant change in the drag coefficient. Soccer balls with grooves exhibited a smaller change in air resistance (Cd) in the supercritical region (20 to 30 m/s; 3.0 × 105 ≤ Re ≤ 4.7 × 105), compared to the ungrooved ball where only the panel orientation was changed. Furthermore, at power-shot speeds (25 m/s), the grooved ball exhibited smaller variations in lift force and side force than the ungrooved ball. These results suggest that a long groove structure on the surface of the soccer ball has a significant impact on the air flow around the ball in the supercritical region, and has the effect of keeping the air flow separation line constant.

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5

Zhang, B., and A. Nakajima. "Spherical surface generation mechanism in the grinding of balls for ultraprecision ball bearings." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 214, no. 4 (April 1, 2000): 351–57. http://dx.doi.org/10.1243/1350650001543241.

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Ultraprecision ball bearings are necessary for high-precision machines and/or high-speed machines since the vibration caused by ball bearings determines the precision of machines as a whole and may make high-speed machines fail to work. To produce ultraprecision ball bearings, it is necessary to clarify spherical surface generation mechanism in the grinding of balls. This paper is the first attempt to investigate the contact trace distribution on the ball surface, which is crucial to spherical surface generation. The kinematic analysis of the contact trace shows that the contact trace is a fixed circle on the ball surface and the contact points are not uniformly distributed on the ball surface. Experimental observation of the contact trace was also carried out. The observation is in good agreement with the analysis. Suggestions on how to distribute the contact trace over the whole ball surface and therefore to improve the precision of balls are given.

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6

Kanai, H., M. Abe, and K. Kido. "Estimation of the Surface Roughness on the Race or Balls of Ball Bearings by Vibration Analysis." Journal of Vibration and Acoustics 109, no. 1 (January 1, 1987): 60–68. http://dx.doi.org/10.1115/1.3269396.

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This paper describes a vibration-based diagnostic method by estimating the surface roughness on the rotating ring or balls in ball bearings. The surface roughness has been measured by a stylus that directly traverses the surface of the ring or balls obtained by taking apart the ball bearing. We developed a new method to estimate accurately the surface roughness by analyzing the short-length vibration signal that is excited when balls encounter flaws on the rotating ring or when races encounter flaws on the balls in a ball bearing. Our experimental results confirm that the roughness estimated by the proposed method agrees with that measured directly by using a stylus even in the case of crack μm wide. We applied this new method to the diagnosis of surface roughness in small-sized ball bearings and inferior samples were detected with a 95.3 percent accuracy rate.

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7

Georgeson, J. D., and D. K. Lieu. "Inspection of Roller Bearing Surfaces with Laser Doppler Vibrometry." Journal of Engineering for Industry 114, no. 1 (February 1, 1992): 123–25. http://dx.doi.org/10.1115/1.2899750.

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Laser Doppler Vibrometry is presented as an effective method of measuring surface profiles of rolling contact bearing balls. An experimental setup and signal processing algorithm are used to obtain digitized surface profiles and statistical measurements of ball surfaces. Tests are made on two different grades of high precision balls and the results are compared. Measurements are presented that match lobed ball frequency results with a resolution of 0.025 microns. The method is well suited for a manufacturing environment because of its durability, simplicity, and high speed.

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8

Kang, J., and M. Hadfield. "The effects of lapping load in finishing advanced ceramic balls on a novel eccentric lapping machine." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 219, no. 7 (July 1, 2005): 505–13. http://dx.doi.org/10.1243/095440505x32427.

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Hot isostatically pressed silicon nitride ball blanks were lapped from a diameter of 13.255 mm to a diameter of 12.7 mm by a novel eccentric lapping machine. A maximum material removal rate of 68 μm/h has been achieved under a nominal lapping load of 43 N per ball. It was found that the material removal rate increased almost linearly with the lapping load within this load range. When the lapping load was higher than 43 N per ball, the material removal rate started to drop and the lapped ball roundness error started to increase. At the highest nominal lapping load of 107 N per ball, surface damage and subsurface damage were found on the lapped balls. Because of the eccentric loading effect, the actual load on an individual ball could be 25–28 per cent higher than the nominal lapping load. The surface residual stresses of lapped balls under different lapping loads were measured, and it was found that the lapping load had less effect than the previous hot isostatic pressing process. Rolling contact fatigue tests were conducted on balls lapped at nominal loads of 43 and 107 N per ball. No failure occurred on the ball lapped at 43 N per ball after 138 × 106 stress cycles. The ball lapped at 107 N per ball failed after 13.3 x 106 stress cycles with a shallow spall with a flat bottom inside. This research suggests that the lapping load for advanced ceramic balls in conventional concentric lapping could be doubled from 20 to 40 N per ball without degrading the surface quality of lapped balls.

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9

Chen, Yi Ji, Jhy Cherng Tsai, and Ya Chen Hsu. "Automatic Inspection System for Surface Defect of Precision Steel Ball." Applied Mechanics and Materials 685 (October 2014): 405–9. http://dx.doi.org/10.4028/www.scientific.net/amm.685.405.

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Precision steel ball is one of the most critical components for rolling transmission. As precision ball affects the performance of precision transmission system, fully inspection of these balls is an urgent need for the industry. This paper is to develop a real-time inspection system for surface defects of precision steel ball with fast and robust method and mechanism. The developed system consists of an optical measurement module as well as a mechanism module for full surface inspecting of the steel ball. The minimum defect and area can be detected by the developed system are 0.1mm and 0.01 mm2 respectively. The developed system has been testified against the designed specifications at speed higher than 3pc/sec and less than 0.5% missing rate. It verified the resolution, accuracy and robustness of the developed system which is capable for final defect inspection of steel balls for grade 100 bearing.

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10

Hong, Sungchan, John Eric Goff, and Takeshi Asai. "Effect of a soccer ball’s surface texture on its aerodynamics and trajectory." Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology 233, no. 1 (October 9, 2018): 67–74. http://dx.doi.org/10.1177/1754337118794561.

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The effect of a soccer ball’s surface texture on its aerodynamics and flight trajectory is not definitively known. For this study, five soccer balls were used, each having 32 panels with different surface textures. Their aerodynamics were examined via wind-tunnel experiments and then several non-spin trajectories were calculated for each ball. The results showed that the aerodynamic forces acting on a soccer ball change significantly depending on the surface texture of the ball, which in turn influences flight trajectories. The study contributes to an understanding of how a soccer ball’s surface influences the aerodynamics, which may impact the future design and development of soccer balls.

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11

Lv, Xun, Ju Long Yuan, Dong Hui Wen, Qian Fa Deng, and Fei Yan Lou. "Study on Ultra-Precision Ball Surface Floating Polishing Kinematics Mechanism." Materials Science Forum 532-533 (December 2006): 109–12. http://dx.doi.org/10.4028/www.scientific.net/msf.532-533.109.

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The high precision balls are requested in national defense, astronautics and high-tech commercial domain urgently. Conventional precision machining methods are sensitive to uniformity of abrasives and machining environment. After precision machining, there are easily to produce thick damaged layer on the ball surface because of machining stress and chemical conversion. On the basis of the floating polishing mechanism, a new scatheless ultra-precision polishing method of ball surface can solve the problems of abrasives uniformity effectively and damaged layer. In order to ensure that the new polishing method polishes ball surface equally, the appropriate angular velocities of the ball should be selected. This paper sets up the mathematical model about the motion of ball. By analyzing and simulating the relationship of the angular velocities, the best processing parameters are acquired.

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12

Lin, Qun, and J. G. Rokne. "Intersection test and blossoming perturbation for disk parametric curves and ball parametric surfaces." Mathematical Problems in Engineering 2006 (2006): 1–28. http://dx.doi.org/10.1155/mpe/2006/29643.

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Errors in curve and surface representation due to inaccuracies in the data are considered and accounted for by introducing disk parametric curves and ball parametric surfaces. Intersection test algorithms and interval extensions using blossoming are discussed for each of the three cases of Bézier curves, tensor product surfaces, and triangular patches. A stability analysis is also performed for each of the three cases. It is shown that under certain restrictions disk Bézier curves and triangular ball Bézier patches are stable with respect to perturbations of the control disks (balls); whereas tensor product ball Bézier surfaces are in general not.

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13

Goff, John Eric, Sungchan Hong, and Takeshi Asai. "Influence of Surface Properties on Soccer Ball Trajectories." Proceedings 49, no. 1 (June 15, 2020): 143. http://dx.doi.org/10.3390/proceedings2020049143.

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In this paper, we summarize our recent research work on soccer balls. Employing wind tunnels and analyses of simulated trajectories, we have gained an understanding of how various surface features influence soccer ball aerodynamics. Wind tunnels provide aerodynamic coefficients for non-spinning soccer balls. The coefficients then help determine the trajectories of various simulated kicked balls. Surface features include panel texturing, seam width, and seam depth. We have determined that small changes in surface texturing can lead to hard-kicked soccer balls experiencing lateral deflections as large as 10%–20% of their horizontal ranges. We have also found that the critical Reynolds number for soccer balls is more strongly correlated with seam width than with seam depth.

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14

Feng, Kai Ping, Zhao Zhong Zhou, Bing Hai Lv, and Ju Long Yuan. "Study on Dual-Plane Ball Polishing Method for Finishing Ceramics Ball." Advanced Materials Research 797 (September 2013): 444–49. http://dx.doi.org/10.4028/www.scientific.net/amr.797.444.

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This paper represents a dual-plane polishing method for ceramics ball. Compared with traditional ball polishing method, its upper and lower plate are all flat and easy to use soft pad to polish, so it can largely reduce the surface mechanical damage and obtain high quality processing surface. This paper analyzes surface polishing trajectory by calculation and simulation to test the polishing trajectory uniformity. A mathematics model of polishing process is established to disintegrate the process of a balls movement. Experiment is operated in dual-plane planetary polishing machine. The result shows that perfect polishing surface and spherical error can be obtained under the proper process parameters, the surface roughness achieves 4nm and the spherical error can reach 0.217μm.

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15

Yuan, Ju Long, Yong Liang Hu, Bing Hai Lv, Qian Fa Deng, and Xin Ma. "Modeling and Simulation of Rotated Dual-Plates Ball-Lapping." Applied Mechanics and Materials 37-38 (November 2010): 679–83. http://dx.doi.org/10.4028/www.scientific.net/amm.37-38.679.

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Different spherical shape models of precision ball-lapping are presented and discussed in this paper. A selective analysis of spherical surface morphology model of rotated dual-plates (RDP) ball-lapping is presented. With combined shape errors of three contact points, the spherical surface morphology is more close to the real surface of precision ball. Simulations show that the spherical surface morphology model of RDP method can well express the shape errors of precision balls. The wear rate is easily obtainable as an empirical function of the contact forces, velocities and material properties of the surfaces in contact. The expansion of the net material removal rate gives the rate of the spherical harmonics. The modeling method can capture the change of single point in the process of lapping. Then the parameters, such as lapping speed, preload, and entry point orientation can be studied using this model in the subsequent research.

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16

Song, Ruo Feng, Qian Qian Wu, and Qian Ming Yang. "Design of Microcontroller System for Surface Scanning of Micro-Steel Ball." Advanced Materials Research 655-657 (January 2013): 740–43. http://dx.doi.org/10.4028/www.scientific.net/amr.655-657.740.

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Based on the detection requirements of surface and sub-surface of micro steel ball, control system of defect scanning is studied, aiming at the problem of unfolded surface of steel ball, STC89S52 microcontroller is considered as the control core, then the feasible method of speed and direction control of step motor that driven by detection device, and hardware interface circuit and design of software solutions of the system are put forward, principles of unfolded surface of steel ball and control system of defect scanning and signal about defect scanning are analyzed, then the result are verified valid through the experiment. The results indicate that unfolded mechanics could be driven and flawed steel balls could be detected by the system of surface scanning of micro steel ball, which meet the design requirements.

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17

Dzierwa, Pawlus, and Zelasko. "The Influence of Disc Surface Topography after Vapor Blasting on Wear of Sliding Pairs under Dry Sliding Conditions." Coatings 10, no. 2 (January 23, 2020): 102. http://dx.doi.org/10.3390/coatings10020102.

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Wear tests were performed using a ball-on-disc tribological tester. In this study, 42CrMo4 steel disc of hardness 40 HRC co-acted with 100Cr6 steel ball with hardness of 60 HRC. Disc surfaces were created using vapor blasting to obtain values of the Sq parameter close to 5 µm. However, other disc surface topography parameters varied. Dry friction tests were carried out. Wear levels of discs and balls were measured using a white light interferometer Talysurf CCI Lite. It was found that the surface topography had a significant impact on tribological properties under dry sliding conditions. The research also allowed to identify significant dependencies between surface topography parameters and wear.

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18

Yu, Kehang, Chen Yang, Jun Wang, Jiabo Yu, and Yi Yang. "Study on the strength of diameter-reducing solder balls by shear and pull tests." Soldering & Surface Mount Technology 31, no. 4 (September 2, 2019): 240–49. http://dx.doi.org/10.1108/ssmt-09-2018-0032.

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Purpose The purpose of this paper is to study the variation of the mechanical strength and failure modes of solder balls with reducing diameters under conditions of multiple reflows. Design/methodology/approach The solder balls with diameters from 250 to 760 µm were mounted on the copper-clad laminate by 1-5 reflows. The strength of the solder balls was tested by the single ball shear test and pull test, respectively. The failure modes of tested samples were identified by combing morphologies of fracture surfaces and force-displacement curves. The stresses were revealed and the failure explanations were assisted by the finite element analysis for the shear test of single solder ball. Findings The average strength of a smaller solder ball (e.g. 250 µm in diameter) is higher than that of a larger one (e.g. 760 µm in diameter). The strength of smaller solder balls is more highly variable with multiple reflows than larger diameters balls, where the strength increased mostly with the number of reflows. According to load-displacement curves or fracture surface morphologies, the failure modes of solder ball in the shear and pull tests can be categorized into three kinds. Originality/value The strength of solder balls will not deteriorate when the diameter of solder ball is decreased with a reflow, but a smaller solder ball has a higher failure risk after multiple reflows. The failure modes for shear and pull tests can be identified quickly by the combination of force-displacement curves and the morphologies of fracture surfaces.

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19

Saknararak, Komate, Phaireepinas Phimpisan, and Chatchapol Chungchoo. "Wear Monitoring of Steel Ball of a CNC Machining Centre by Using Surface Roughness of Finished Test Pieces." Key Engineering Materials 656-657 (July 2015): 410–15. http://dx.doi.org/10.4028/www.scientific.net/kem.656-657.410.

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Currently, there are several methods for indicating wear of the steel ball and screw shaft components of CNC machining centres. These include wear prediction of the steel ball and screw shaft of the ball screw by using the value of backlash. This value, generally, has to be determined using expensive equipment such as a laser interferometer or a ball bar. In order to reduce the monitoring cost of ball screw wear, especially steel ball wear, a new monitoring technique is introduced. This technique was developed from a correlation between steel ball wear and the surface roughness of the machined surface of a test piece. In this research, the balls were subjected to artificial wear which were achieved by using a barrel tumbling process. Experimental results indicated that ball wear causes increase in surface roughness of a machined test piece. Employing these results, an equation for estimating steel ball wear was developed. Research results also showed that this new technique can reduce monitoring cost significantly compared with the cost of conventional methods.

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20

Herbudiman, Bernardinus, Erma Desmaliana, and Andhi Muhammad Irawan. "Mechanical properties of concrete with substitution of coated styrofoam balls on coarse aggregate." MATEC Web of Conferences 276 (2019): 01028. http://dx.doi.org/10.1051/matecconf/201927601028.

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Substitution of Styrofoam balls on coarse aggregates reduced concrete self-weight. Coating on Styrofoam ball surface makes ball has shell on its surface and could increase the adhesive strength between ball surfaces and cement paste. The coating materials made by mixing of Portland cement and RCC-15 (Residual Catalytic Cracker-15) as pozzolanic material. 20 mm diameter Styrofoam balls are used. Coarse aggregates substituted by 5%, 15%, and 20% Styrofoam balls. The test specimens used three 10x20cm cylinders for each variant. Beam specimens of 15x15x60cm used for bending strength test by third point loading method. The testing of mechanical properties were 7, 14, and 28 days compressive strengths, 28 days split-tensile strengths and 28 days flexural strengths. The experimental results of concrete with various Styrofoam ball substitutions of 5%, 15%, and 20% at 28 days show the average compressive strengths are 27.6 MPa, 24.3 MPa, and 20.3 MPa, the splittensile strengths are 2.5 MPa, 2.2 MPa, and 1.7 MPa, and the flexural strengths are 5 MPa, 4.5 MPa, and 3.8 MPa, respectively. The compression strength could be predicted by density ratio method and air content method. The experimental results show that all of the variants of Styrofoam ball coarse aggregates concrete are adequate to achieve structural strength, and have nearly compressive strengths compared with the prediction by density ratio method and air content method. Styrofoam balls substitution content could be increased to make the concrete density below 1,900 kg/m3 and compressive strength above 17.5 MPa to reach structural lightweight concrete performance.

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21

Pinto, Gustavo, Andresa Baptista, Francisco Silva, Jacobo Porteiro, José Míguez, and Ricardo Alexandre. "Study on the Influence of the Ball Material on Abrasive Particles’ Dynamics in Ball-Cratering Thin Coatings Wear Tests." Materials 14, no. 3 (February 1, 2021): 668. http://dx.doi.org/10.3390/ma14030668.

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Micro-abrasion remains a test configuration hugely used, mainly for thin coatings. Several studies have been carried out investigating the parameters around this configuration. Recently, a new study was launched studying the behavior of different ball materials in abrasive particles’ dynamics in the contact area. This study intends to extend that study, investigating new ball materials never used so far in this test configuration. Thus, commercial balls of American Iron and Steel Institute (AISI) 52100 steel, Stainless Steel (SS) (AISI) 304 steel and Polytetrafluoroethylene (PTFE) were used under different test conditions and abrasive particles, using always the same coating for reference. Craters generated on the coated samples’ surface and tracks on the balls’ surface were carefully observed by Scanning Electron Microscopy (SEM) and 3D microscopy in order to understand the abrasive particles’ dynamics. As a softer material, more abrasive particles were entrapped on the PTFE ball’s surface, generating grooving wear on the samples. SS AISI 304 balls, being softer than the abrasive particles (diamond), also allowed particle entrapment, originating from grooving wear. AISI 52100 steel balls presented particle dynamics that are already known. Thus, this study extends the knowledge already existing, allowing to better select the ball material to be used in ball-cratering tests.

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22

Zhang, Weiguang, Jusang Lee, Hyung Jun Ahn, Qiqi Le, Meng Wu, Haoran Zhu, and Jing Zhang. "Field Investigation of Clay Balls in Full-Depth Asphalt Pavement." Materials 12, no. 18 (September 6, 2019): 2879. http://dx.doi.org/10.3390/ma12182879.

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Clay ball is a pavement surface defect which refers to a clump in which clay or dirt is mixed with hot asphalt mixture. Clay ball is typically caused by a combination of aggregate contamination of clay or soil, high aggregate moisture, and low production temperature at the asphalt plant. It usually appears a few weeks or months after paving under traffic load, after being liquefied and knocked from the pavement surface. Clay balls can be the source of potholing, raveling, and other issues such as moisture infiltration and reduced ride quality. This paper presents an investigation of the clay balls on US-31 one winter after construction in Hamilton County, Indiana. In order to understand the pavement condition, their severity was measured using both visual observation and infrared image collection system. In addition, a clay ball amount, its distribution pattern, and cores condition were evaluated. A precipitation effect on clay ball formation was investigated for finding a cause of the clay balls. The investigation found that infrared image collection system was appropriate in detecting the clay balls. The clay balls were elliptic in shape with 2.5 cm to 10 cm in diameter, and the maximum clay ball depth was almost penetrating the entire surface course. It was also found that the asphalt paving on the raining days or right after raining could increase the potential of clay balls. Monitoring of aggregate moisture during construction on or after raining days should be able to reduce the risk of clay balls.

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23

Kang, J., and M. Hadfield. "The polishing process of advanced ceramic balls using a novel eccentric lapping machine." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 219, no. 7 (July 1, 2005): 493–503. http://dx.doi.org/10.1243/095440505x32382.

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The finishing process of advanced ceramic balls can be divided into two steps. The first step is lapping in which most of the stock from the ball is removed at a higher material removal rate. The second step is polishing in which the required ball surface roughness, roundness, and dimensional and geometric accuracy are achieved. In polishing, the abrasive particle size is 1 μm, and the load and speed are lower than lapping. A novel eccentric lapping machine is used for polishing hot isostatically pressed (HIPed) silicon nitride balls. In the initial polishing stage, the polishing load is demonstrated as being most influential in the reduction of surface roughness value Ra. However, in the later polishing stages, the erosive process played a major role in the further reduction of Ra, although the high roughness peaks cannot be removed by erosive process alone. Experimental results also show that, in order to achieve desired surface roughness value, the initial surface quality of the upper plate should be reasonably high, and deep scratches on the ball surface from previous lapping processes should be avoided. The best polishing results achieved were surface roughness values of Ra of 0.003 μm and r.m.s. ( Rq) of 0.004 μm, ball roundness of 0.08–0.09 μm. This proves that the novel eccentric lapping machine is also suitable for polishing advanced ceramic balls.

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24

Ishii, Takaaki, Hiroki Yamawaki, and Hidetoshi Ohuchi. "An Ultrasonic Motor Using Thrust Bearing with Dimple Structure on the Friction Surface." Key Engineering Materials 649 (June 2015): 54–59. http://dx.doi.org/10.4028/www.scientific.net/kem.649.54.

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An ultrasonic motor using thrust ball bearing with dimple structure on the friction surface has been proposed. The bearing balls are rotated by the friction force caused by the ultrasonic vibration of the stator, and transfer torque to the rotor. The dimple structure on the sliding surface can hold the ball position and rotate the balls and the rotor without a retainer. The newly proposed motor can avoid the friction loss between balls and the retainer. The balls of 2.4 mm in radius are used and the radii of the curvature of the dimples of 2.0 mm and 3.0 mm are used in this research. The radius difference changes the contact condition between the balls and the dimple structure. Fundamental motor characteristics are measured and discussed.

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25

Berdeni, Y., A. Champneys, and R. Szalai. "The two-ball bounce problem." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, no. 2179 (July 2015): 20150286. http://dx.doi.org/10.1098/rspa.2015.0286.

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A popular classroom demonstration is revisited in which a light ball and a much larger heavier ball are vertically aligned and dropped together onto a hard surface. Careful experimental data obtained using a high-speed camera is compared to a lumped-mass Newtonian restitution model. Good macroscopic agreement is found, provided there is sufficient separation between the two balls as they are dropped. An alternative continuum model based on elastic membrane theory is developed to explain the limit in which the balls are initially touching. The model assumes the lower ball deforms to a truncated sphere upon its impact with the floor, exciting an elastic wave which subsequently launches the upper ball like a particle on a trampoline, before the lower ball leaves the ground. A favourable comparison with experimental data is found for the case of negligible initial separation between the balls.

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26

McElwaine, J., and K. Nishimura. "Ping-pong ball avalanche experiments." Annals of Glaciology 32 (2001): 241–50. http://dx.doi.org/10.3189/172756401781819526.

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AbstractPing-pong ball avalanche experiments have been carried out for the last 3 years at the Miyanomori ski jump in Sapporo, Japan, to study three-dimensional granular flows. Up to 550 000 balls were released near the top of the landing slope. The balls then flowed past video cameras positioned close to the flow, which measured individual ball velocities in three dimensions, and air-pressure tubes at different heights. The flows developed a complicated three-dimensional structure with a distinct head and tail, lobes and “eyes”. “Eyes” have been observed in laboratory granular flow experiments, and the other features are similar not only to snow avalanches” but also to other large-scale geophysical flows. The velocities attained showed a remarkable increase with the number of released balls. A power law for this relation is derived by similarity arguments. The air-pressure data are used to deduce the structure of the airflow around the avalanche and, in conjunction with the kinetic theory of granular matter, to estimate the balance of forces in the avalanche head.

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Li, Cheng Nan, Ye Yan, Yu Hong Gai, Bao Min Li, Wei Du, and Mu Sen Li. "Failure Analysis of GCr15 Steel Balls in Ball Screw Pair." Applied Mechanics and Materials 651-653 (September 2014): 24–28. http://dx.doi.org/10.4028/www.scientific.net/amm.651-653.24.

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Based on macro morphology, metallographic microstructure, field emission scanning electron microscope observations and microhardness testing, failure analysis of the GCr15 steel balls in the ball screw pair was dealt with in this paper. The experimental results showed that small scratches and pits were evenly distributed on the surface of the A steel ball which showed features of wear failure. Characteristics of the B steel ball surface morphology were contacted to fatigue failure. Microstructure observation on the cross-section of the B steel ball showed that martensite and carbides were uneven distributed which were caused by the uneven elements distribution in the raw materials. It was the main cause of this abnormal failure. Therefore, the quality of the raw materials needed to be strictly controlled and the reasonable heat treatment process should be adopted to ensure the quality of the steel balls.

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28

Hong, Sungchan, and Takeshi Asai. "Aerodynamic Differences between New and Used Soccer Balls." Applied Sciences 11, no. 16 (August 4, 2021): 7204. http://dx.doi.org/10.3390/app11167204.

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The surface structure of soccer balls, such as the number and shapes of the ball panels, has recently changed, and research on the aerodynamics and flight trajectories of new soccer balls is actively proceeding. However, these studies are focused on new soccer balls, whereas the used soccer balls were never studied. In this study, the aerodynamic characteristics of soccer balls kicked 1000 times by a robot were investigated through wind tunnel tests. The results were compared with those obtained using new soccer balls. Regarding the aerodynamic characteristics of the soccer balls, it was found that the critical Reynold number, Recrit, changes with usage. This is related to the transition from laminar to turbulent flow of airflow around the ball. The comparison of the drag coefficients of the balls at Recrit showed that the drag coefficients of the new and used Telstar18 balls were 0.15 (Re = 2.5 × 105) and 0.14 (Re = 2.2 × 105), respectively; those of the new and used Merlin were 0.13 (Re = 2.8 × 105) and 0.13 (Re = 2.2 × 105), respectively; and finally, those of the new and used Derbystar were 0.14 (Re = 2.1 × 105) and 0.14 (Re = 2.1 × 105), respectively. The surface conditions of a soccer ball, such as the surface roughness and surface damages, are essential factors to determine the aerodynamics of the soccer balls.

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Fan, Na, Liqiang Chai, Peng Wang, and Jun Liang. "The effect of ceramic friction pairs on the tribocorrosion behavior of AISI 304 stainless steel in seawater." Industrial Lubrication and Tribology 71, no. 6 (August 12, 2019): 779–86. http://dx.doi.org/10.1108/ilt-10-2018-0377.

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Purpose This paper aims to study the tribocorrosion behavior of 304 stainless steel (SS) sliding against SiC and Si3N4 counterparts in artificial seawater. Design/methodology/approach The tribocorrosion behavior of 304SS sliding against SiC and Si3N4 balls in artificial seawater has been investigated. The tests were conducted using a ball-on-disk rig equipped with an electrochemical workstation. The friction coefficient, surface morphology, wear volume and current density were determined. Findings When 304SS sliding against SiC ball, a smooth surface with a silica layer was formed on the top, which led to the low friction coefficient, current density and small wear volume. For 304SS-Si3N4 tribo-pair, a lot of metal debris was scattered on contact surfaces leading to high friction coefficient, current density and big wear volume. Research limitations/implications This research suggests that the lubrication effect of silicon-based ceramics is related to counterpart specimen in artificial seawater. Practical implications The results may help us to choose the appropriate ceramic ball under seawater environment. Originality/value The main originality of the work is to reveal the tribocorrosion behavior of 304SS sliding against SiC and Si3N4 balls, which help us to realize that the Si3N4 ball as water-lubricated ceramics could not exhibit lubrication effect when coupled with 304SS in artificial seawater.

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30

LENART, Agnieszka, Paweł PAWLUS, Andrzej DZIERWA, and Mirosław TUPAJ. "THE EFFECT OF SURFACE TEXTURE OF STEEL DISC ON FRICTION AND FRETTING WEAR." Tribologia 280, no. 4 (August 1, 2018): 39–48. http://dx.doi.org/10.5604/01.3001.0012.7527.

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Fretting tests were performed using an Optimol SRV5 tribotester in a ball-on-flat scheme. Balls from 100Cr6 steel of 60 HRC hardness and diameters of 10 mm co-acted with discs from 42CrMo4 steel of 47 HRC hardness under dry gross fretting conditions. Tests were performed at 300C and 25–35% relative humidity, and the number of cycles was 18000. During each test, the normal load was kept constant. Six sets of experiments were conducted. Discs had different surface textures as the result of machining. It was found that the lowest coefficients of friction were obtained for anisotropic surfaces when ball movements were perpendicular to main disc texture directions.

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Loh, N. H., S. C. Tam, and S. Miyazawa. "Surface hardening by ball burnishing." Tribology International 23, no. 6 (December 1990): 413–17. http://dx.doi.org/10.1016/0301-679x(90)90057-v.

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32

Zhao, Yang, Heng Liu, and Bowen Fan. "Traction effects on the dynamics of ball bearings." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 235, no. 4 (October 7, 2021): 641–52. http://dx.doi.org/10.1177/14644193211047385.

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In the paper, a combined model of traction and ball bearings dynamics is established, considering the interaction among the cage, races, and balls. A curve-fitted traction model, which can be used to analyze the effect of the geometry of the bearing and parameters of the lubricant, is applied. The traction that is affected by certain parameters is analyzed; then, the effect of the traction on ball bearings is investigated. The displacements of balls and contact angles are different under different surface roughness. The changes in displacements of balls and contact angles are obtained with different roughness, load, and velocities. The amplitudes of axial displacement of balls are bigger with the roughness being higher. The amplitudes of ball-inner contact angles increase with greater roughness, and the amplitudes of ball-outer race contact angles decrease with greater roughness. The simulated vibration results of ball bearings under different levels agree with the actual by the model.

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33

Neilson, P. J., and R. Jones. "An exact method for the sphericity measurement of soccer balls." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 217, no. 5 (May 1, 2003): 715–19. http://dx.doi.org/10.1243/095440503322011452.

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The most popular games in the world are ball sports. Generally, ball properties such as weight, circumference and sphericity are specified in the rules and determine the ball quality. The current method of sphericity measurement employed by the Federation International Football Association (FIFA) is to measure the ball diameter at 16 points and then calculate the mean average. The sphericity of the ball is inferred from the diametric measurements. Unfortunately, diameter measurement does not guarantee sphericity, and a new technique has been developed to measure ball sphericity using a coordinate measuring machine (CMM). In this method a representative sample of the ball surface is probed/measured to give three-dimensional coordinates of defined points, nominally the ball panel centres. Computer software is then used to fit a least-squares sphere approximation to the ball data, giving a unique value for ball sphericity. Measurements were taken of six different brand type balls, with a sample of four balls of each brand; all balls were inflated to the same pressure. The results show that the new method of sphericity measurement suggested here gives a unique assessment of sphericity. The errors obtained from the new method are such that the FIFA error specification may need reconsideration.

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34

Lv, Bing Hai, Ju Long Yuan, F. Cheng, and Fan Yang. "Influence of Supporting Characteristics on Sphericity of Ceramic Balls in Rotated Dual-Plates Lapping Process." Advanced Materials Research 69-70 (May 2009): 69–73. http://dx.doi.org/10.4028/www.scientific.net/amr.69-70.69.

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Ceramic balls have become an important component in advanced bearings, and the sphericity of balls is a key qualification focused in lapping process. An investigation on the effect of dynamic behavior of ball support system on the performance of ball lapping in rotated dual-plates lapping method is carried out. Sinusoidal waveform in terms of Fourier analysis is employed to express the shape error of the ball surface, and a dynamic model for support is setup. It is found with numerical calculation that the variation of lapping load lags behind the variation of the shape error for the damping of support. A lower natural frequency of the support system, higher spin speed of balls and a larger value of spin angle in RDP lapping are better to rectify the shape error of balls and reduce the lagged effect. It is concluded that dynamics of lapping system must be taken into consideration in order to understand comprehensively the spherical surface generation mechanism.

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35

Wu, Yong Bo, Wei Xing Xu, M. Fujimoto, and T. Tachibana. "Ceramic Balls Machining by Centerless Grinding Using a Surface Grinder." Advanced Materials Research 325 (August 2011): 103–9. http://dx.doi.org/10.4028/www.scientific.net/amr.325.103.

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This paper proposes a novel method for machining ceramic balls by centerless grinding technique performed on a surface grinder. In this method, a compact unit consisting mainly of an ultrasonic shoe, an ultrasonic regulator, a relay controller, a blade, a stopper and their respective holders is installed on the worktable of a surface grinder to conduct centerless grinding operations of ceramic balls. The ultrasonic shoe and regulator are produced by bonding a piezoelectric ceramic device (PZT) onto a metal elastic body, and when two phases of AC voltage are applied to the PZT an elliptic motion occurs on their end-faces which can be used to control the ball rotational motion in the radial and axial direction of the wheel, respectively. The function of the relay controller is to regulate the alternating current “on” and “off” time which is applied on the regulator for achieving the whole spherical surface grinding process. A grinding unit was actually constructed and it was experimentally confirmed that the ball rotational speed can be controlled well by the shoe or regulator. Grinding tests were subsequently carried out and the obtained results indicated that the constructed grinding unit performed well on actual ball centerless grinding operations.

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36

Dohotaru, Ion, and Maxim Casian. "Geometric Aspects and Particularities in the Functioning of a Reductor with Balls." Applied Mechanics and Materials 657 (October 2014): 500–503. http://dx.doi.org/10.4028/www.scientific.net/amm.657.500.

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Benefits of mechanism with balls are to promote their interests in different aspects in different fields of modern technology. May be remarked considerable success in screws with balls, guides, couplings etc. Are in the ascendancy searches for optimal solutions in speed-reducers with balls. One of the possible contributions to the research for technical solutions in this area is presented below. It shows the geometric particularities and configuration of a spherical ball transmission, constructive modeling and simulation of function. On an outside spherical surface of one wheel there is a sine wave path ball race. The second wheel has on an internal surface longitudinal inclined channels in which the balls are located.

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37

LIN, ZICHAO, FANGHONG SUN, and BIN SHEN. "FRICTION PROPERTIES OF POLISHED CVD DIAMOND FILMS SLIDING AGAINST DIFFERENT METALS." Surface Review and Letters 23, no. 02 (February 29, 2016): 1550096. http://dx.doi.org/10.1142/s0218625x15500961.

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Owing to their excellent mechanical and tribological properties, like the well-known extreme hardness, low coefficient of friction and high chemical inertness, chemical vapor deposition (CVD) diamond films have found applications as a hard coating for drawing dies. The surface roughness of the diamond films is one of the most important attributes to the drawing dies. In this paper, the effects of different surface roughnesses on the friction properties of diamond films have been experimentally studied. Diamond films were fabricated using hot filament CVD. The WC-Co (Co 6[Formula: see text]wt.%) drawing dies were used as substrates. A gas mixture of acetone and hydrogen gas was used as the feedstock gas. The CVD diamond films were polished using mechanical polishing. Polished diamond films with three different surface roughnesses, as well as the unpolished diamond film, were fabricated in order to study the tribological performance between the CVD diamond films and different metals with oil lubrication. The unpolished and polished CVD diamond films are characterized with scanning electron microscope (SEM), atomic force microscope (AFM), surface profilometer, Raman spectrum and X-ray diffraction (XRD). The friction examinations were carried out by using a ball-on-plate type reciprocating friction tester. Low carbide steel, stainless steel, copper and aluminum materials were used as counterpart balls. Based on this study, the results presented the friction coefficients between the polished CVD films and different metals. The friction tests demonstrate that the smooth surface finish of CVD diamond films is beneficial for reducing their friction coefficients. The diamond films exhibit low friction coefficients when slid against the stainless steel balls and low carbide steel ball, lower than that slid against copper ball and aluminum ball, attributed to the higher ductility of copper and aluminum causing larger amount of wear debris adhering to the sliding interface and higher adhesive strength between the contacting surfaces.

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38

Shiou, Fang-Jung, and Assefa Asmare Tsegaw. "Ultra Precision Surface Finishing Processes." International Journal of Automation Technology 13, no. 2 (March 5, 2019): 174–84. http://dx.doi.org/10.20965/ijat.2019.p0174.

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Surfaces of different complex shapes are aspirated part of many scientific measuring devices, medical, astronomical, and other precision activity utilizations. Components at miniaturized level should meet required surface roughness for the intended applications. Surface finishing of freeform and miniaturized components are always difficult and need to look for a new way out. In this study, an attempt was made to improve surfaces roughness of selected, most frequently used, engineering materials using different innovative processes, which can be integrated with CNC machine centers. An advanced automated surface finishing tools such as ball burnishing embedded with load cell, vibration assisted polishing, and self-propelled abrasive multi-jet polishing tools are proposed. Ball burnishing is advantageous for pre-machining process of ball polishing. Using the polishing device embedded with load cell, the constant force polishing is achieved. To reduce the volumetric wear of a polishing ball, vibration assisted polishing device is also integrated. Moreover, self-propelled abrasive multi-jet polishing tool, which achieves 93.33% improvement of surface roughness for lapped optical glass of BK7 has been subjugated from Ra 0.300 μm to 0.020 μm. These tools can be miniaturized and applicable in small micro CNC machining centers.

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Mukhtar, N. Z. F., M. Z. Borhan, Mohamad Rusop, and Saifollah Abdullah. "Effect of Milling Time on Particle Size and Surface Morphology of Commercial Zeolite by Planetary Ball Mill." Advanced Materials Research 795 (September 2013): 711–15. http://dx.doi.org/10.4028/www.scientific.net/amr.795.711.

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Ball milling is a top down approach and a method to reduce size of particle while Zeolite is a valuable inorganic materials having wide variety of applications. In this paper, ball milling of commercial synthetic Zeolite powder was studied with their time varied. Wet ball milling was selected as a potential means to decrease the particle size of Zeolite over dry grinding. The parameters that included in this study were rotational speed, balls to powder ratio, water to powder ratio and milling time. These nanozeolite were characterized via Zeta-sizer nanoseries of particle sizer, FESEM, and also FTIR. Results showed that commercial synthetic Zeolite powder with particle size larger than 45 μm may be reduced into the size range between 0.2 0.3 μm by planetary ball mill.

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40

Fadli, Ahmad, Silvia Reni Yenti, Agung Prabowo, Siska Priscillia Aledya, Rawdatul Fadila, and Reno Susanto. "The Synthesis of Hydroxyapatite Powder Using Shaker Mill Technique." Journal of Southwest Jiaotong University 56, no. 2 (April 30, 2021): 22–31. http://dx.doi.org/10.35741/issn.0258-2724.56.2.3.

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Hydroxyapatite is a material that has the same structure and composition as the main minerals of human teeth and bones. This study's purpose was hydroxyapatite synthesis and determining the effect of variations in the ball sizes, the ratio of a mass of precursors to balls size, milling time, and ball size ratio of crystals and particles, surface area and morphology of hydroxyapatite produced by the mechanochemical method. Two different ball sizes (3mm and 6mm) and three different powder to ball ratio of 1:1.44; 1:2.88; and 1:4.32 were milled for 6 hours. Furthermore, the ball size ratio between the small ball (3 mm) and large ball (6 mm) was 1:1, 1:3, and 3:1 were milled for 2, 4, and 6 hours. The synthesized powder was analyzed by X-ray diffraction, Particle Size Analysis, Brunauer-Emmet-Teller analysis, and Scanning Electron Microscopy to confirm hydroxyapatite structure formation with nanocrystallite size and morphology in all variables. The crystallite size increased as the powder to ball ratio increased. The surface area at powder to ball ratio of 1:2.88 and ball size of 3 mm was 19.51 m2/g, while at ball size ratio of 1:1, it was 18.82 m2/g. The morphology of hydroxyapatite was uniform to granular with mol ratio Ca/P 1.81 for powder to ball ratio and ball size variation.

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41

Xie, Feng Qin, Lin Jing Xiao, Ya Peng Lu, and Hua Yu Zhang. "Design of the Eddy Current Sensor of Steel Ball Nondestructive Detection." Applied Mechanics and Materials 271-272 (December 2012): 842–46. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.842.

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The ball surface and sub-surface defects can be test by the eddy current nondestructive method. The core part of the eddy current system is the sensor’s design, including the coil and the process of induction signals. At the end, through experiment of detecting a set of defect ball, with a better result. It’s shows that the amplitude of the detection signal is proportional to the depth of the steel balls crack.

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42

Supancic, Peter, Robert Danzer, Walter Harrer, Zhong Hua Wang, Stefan Witschnig, and Oskar Schöppl. "Strength Tests on Silicon Nitride Balls." Key Engineering Materials 409 (March 2009): 193–200. http://dx.doi.org/10.4028/www.scientific.net/kem.409.193.

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For some years ceramic bearing balls based on silicon nitride have been routinely used in technical practice. An important property of bearing balls is their strength, but appropriate testing methods are still missing. In this paper four different methods for strength testing are applied to commercial bearing balls. Each of the tests needs a different type of specimen, their preparation needs a very different effort, and the stress state applied to the specimens is also very different. This causes pros and cons, which are discussed in detail. The conventional 4-point bending test characterises the material in the interior of the balls. The applied stress state is uniaxial. The machining of the bending bars out of the balls is time intensive and costly. The ball on three balls test also characterises interior of the balls. The stress state is biaxial. The machining of the disc shaped specimens out of the balls is less expensive than the production of bending bars, but the finish of the tensile loaded surface needs special care. The data of both types of tests can be converted into each other using Weibull theory. The specimens in the triple ball crush test are as-received bearing balls, which are squeezed together. This causes some kind of contact loading, as will also occur in service. Failure is caused by the creation and growth of contact cracks, followed by a collapse of the compressed and cracked material. A detailed analysis of test results is complicated. It can be speculated that the component’s behaviour is mainly influenced by the toughness of the material and that the flaws in the material or at the component’s surface are of less significance. In the newly developed notched ball test the highest stressed region is a part of the original surface of the balls. Machining of the notch is straightforward. The stress state is almost uniaxial. The strength depends on size of flaws in the surface region. Therefore the notched ball test is a relevant measure to characterize the quality of the bearing balls.

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43

Lane, Ben, Paul Sherratt, Hu Xiao, and Andy Harland. "Characterisation of ball impact conditions in professional tennis: Matches played on hard court." Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology 230, no. 4 (August 1, 2016): 236–45. http://dx.doi.org/10.1177/1754337115617580.

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To assess ball performance for research and development purposes requires greater understanding of the impact conditions a tennis ball experiences in professional tournament play. Ball tracking information taken from three consecutive years of an ATP 250 tour event played on hard court was analysed. The frequency of first serves, second serves, racket impacts and surface impacts was assessed per game and extrapolated to show how many impacts a single ball is subjected to. Where applicable the pre- and post-impact velocities and angles were found, and the distribution of each was analysed. In total, data from 65 matches comprising 1505 games were analysed. On average, each game contained 70.26 (±16.23) impacts, of which 9.23%, 3.16%, 37.78% and 49.83% were first serves, second serves, racket impacts and surface impacts, respectively. As a result, assuming all balls in play are used evenly, a single ball is expected to be subjected to 105 (±24) impacts over the course of the nine games that it is in play. The results of the investigation could be used to design a wear protocol capable of artificially wearing tennis balls in a way that is representative of professional play.

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44

Upadhyay, Pankaj K., Pankaj Agarwal, A. R. Ansari, and Ravindra Mohan. "Mechanism of Ball Burnishing Process for Radius of Curvature for Elastic and Plastic Deformation between Ball and Hole." Material Science Research India 9, no. 1 (June 20, 2012): 133–38. http://dx.doi.org/10.13005/msri/090119.

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Ball burnishing (ballizing) chip less process which produces a smooth surface and surface hardness. The pressure generated by the ball exceeds a plastic deformation stage and create a new surfaces. The plastic deformation created by ball burnishing is a cold flows under pressure into the valleys surface is smooth, Ballizing is a technique for sizing and finishing holes in metal components. It is a rapid and relatively low cost process. A suitably oversized precision ball is pressed through an unfinished undersized hole, A simple tooling such as a hardened ball and a push rod is required for this process. However an intensive analysis is essential for analysing the mechanics of the process. The ball burnishing is very useful process to improve upon surface roughness and can be employed. It will help to impart compressive stress and fatigue life can be improved. The Al alloy is a difficult to machine material and burnishing is difficult process for this grade material. A low surface roughness and hardness was obtained in increasing the operating parameters. It may develop flaw and micro cracks on the surface.

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45

Ohara, Satoshi, Zhenquan Tan, and Hiroya Abe. "Novel Mechanochemical Synthesis of Carbon Nanomaterials by a High-Speed Ball-Milling." Advanced Materials Research 284-286 (July 2011): 755–58. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.755.

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A novel mechanochemical approach to produce sophisticated carbon nanomaterials is reported. It is demonstrated that carbon nanostructures such as carbon nanotubes and carbon onions are synthesized by high-speed ball-milling of steel balls. It is considered that the gas-phase reaction takes place around the surface of steel balls under local high temperatures induced by the collision energy in ball-milling process, which results in phase separated unique carbon nanomaterials.

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46

Cross, Rod. "Billiard ball vs rubber ball collisions." Physics Education 57, no. 3 (March 14, 2022): 033001. http://dx.doi.org/10.1088/1361-6552/ac5156.

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Abstract When two billiard balls collide head-on on a smooth, horizontal surface, momentum and kinetic energy are both conserved to a good approximation. If the experiment is repeated with two rubber balls, then kinetic energy is not conserved and neither is momentum. The latter result can be explained in terms of the external friction forces involved.

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47

Yang, S.-C., and C.-K. Chen. "The surface geometry of rollers with skew rolling of steel balls." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 215, no. 5 (May 1, 2001): 523–32. http://dx.doi.org/10.1243/0954406011520922.

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The ball shaping process is considered from a geometric viewpoint as a meshing pair of conjugate surfaces at the precise rolling stage. This viewpoint offers a simple method and procedure for determining the groove design of each forming roll in the skew rolling process of steel balls. Based on the envelope theory, a shape design of the forming roll is a composite of two helical grooves with constant pitch and variable pitch. Through this method, the mathematical model of the forming rolls for skew rolling, which can be used to design and manufacture a skew roller for manufacturing steel balls, can be derived and simulated. Finally, the required cutter path is provided for a spherical-end cutter in the manufacturing process. The size of the spherical-end cutter may be identical with or smaller than that of the steel ball.

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48

Singh, T., and V. K. Verma. "Tribological Studies on Bearing Balls of Different Composition Using Certain Heterocyclic Compounds as Potential E.P. Additives." Journal of Tribology 112, no. 4 (October 1, 1990): 614–17. http://dx.doi.org/10.1115/1.2920305.

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Tribological studies on 12.7 mm dia steel bearing ball specimens of different composition have been carried out in a “4-ball machine” using certain potentially active heterocyclic compounds-paraffin oil admixtures. EP efficiency of these additives has been compared to a commercial sulphur-phosphorus additive. 2-Phenyl-3-phenylimino-5-p-methoxyphenylimino-1,2,4-thiadiazolidine has been found to be quite effective in the lubrication of bearing balls of different compositions. The topography and surface chemistry of the used bearing ball specimens have been examined using Scanning Electron Microscopy and Scanning Auger Electron Spectroscopy techniques respectively. Employing a suitable additive, the costlier alloy steel balls can be replaced by cheaper low carbon and chromium balls.

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49

Chen, Cheng, Fangyu Wang, and Hui Lin. "Experimental Study on Dam-Break-Like Tsunami Surge Impacts on Small Balls Climbing on Different Slopes." Journal of Earthquake and Tsunami 14, no. 06 (August 6, 2020): 2050022. http://dx.doi.org/10.1142/s1793431120500220.

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An experimental study was carried out to investigate the tsunami surge impacts on small balls climbing on different slopes. Dam-break flows were generated in a flume to simulate tsunami surge. The water surface profiles at the sluice gate were observed, the tsunami inundation height and the surge velocity in the flume were measured, and the maximum climbing heights of small balls on different slopes were recorded. Results show that the dam-break speed and the tsunami surge strength increase with increasing reservoir water level. The increasing tsunami inundation height, the decreasing ball density, and the decreasing ball diameter have positive effects on the maximum ball climbing height. Based on the normalized experimental data, equations for estimating the maximum ball climbing heights on different slopes were proposed as functions of the inundation height, the ball diameter, and the ball density. The calculated values from the equation are generally within [Formula: see text]% of the measured values in the experimental ranges.

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50

Widodo, Teguh Dwi, Rudianto Raharjo, Sugiono, and Arif Wahyudiono. "Effect of Low Temperature Steel Ball Peening on the Hardness of SS 316L." Key Engineering Materials 791 (November 2018): 105–10. http://dx.doi.org/10.4028/www.scientific.net/kem.791.105.

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The aim of this research is to investigate the hardness of implant material Stainless Steel (SS) 316L due to ball peening at low temperature. In this paper, SS316L ball peening was conducted in various cryogenic temperature. The steel ball peening mechanism was bombarded on metal surface using peening ball. The shot peening treatment was performed for 10 minutes using steel balls with the size of 5 mm and 6 Bar compressed air flow. The treatment temperatures were carried out at-35°C, -45°C, and-55°C respectively. The results show that the hardness of SS316L after steel ball peening processes increasing as decreasing temperature treatment.

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