Investigation of Drilling Process Parameters of Palmyra Based Composite

The drilling process is the most essential in the final assembly of the mechanical parts. Natural fiber based composites replace traditional materials due to their advantages, such as strength to weight ratio, availability, and environmental hazards. In this work, an attempt has been made to find the minimum thrust force produced by the drill tool at specified drilling process parameters. The drilling process parameters used for the investigation are rotational speed, tool feed, and resins. The spindle speed and feed rate are selected with three levels. Three resin materials were used, namely, epoxy, polyester, and vinyl ester. Taguchi’s L27 orthogonal array was implemented. The result shows that the candlestick drill bit generated lesser thrust force at the specified drilling process parameters, followed by the twist and step cone drill bits.

Kinetic criteria for evaluating the performance of roller-cone drill bits

Research objective is to work out a method of evaluating the performance of roller-cone drill bits by kinetic criteria. Introduction. It is difficult to determine the absolute criteria for the performance of rock cutting tools. Therefore, the relative values of wear resistance of the cutting structure of roller-cone bits and their relative mechanical rates of drilling are adopted as process criteria. Methods of research. The calculation and analysis of kinetic criteria for evaluating the performance of drill bits have significant differences. Taking them into account is important when studying various modifications of rock cutting tools. The set of kinetic criteria gives a picture of the relative performance of the bit using the model of the well bottom close to the real one. The set of kinetic characteristics (criteria) is conventionally called the kinetic datasheet of the drill bit. The key points of constructing an analytical model of the drill bit operation on the deformable well bottom have been considered. Scope of results. This technique provides for a comparative evaluation of roller-cone drill bits of various modifications, allows for finding feedback, i.e. searching for the appropriate combination of geometrical parameters of the rock cutting tool according to given kinetic characteristics. The versatile approach intended for use in the study of the performance of rock cutting tools allows the most complete and accurate evaluation of the influence of one factor or another on the final result.

Can NFL Combine Results be Used to Estimate NFL Defensive Players Longevity?

The National Football League Scouting Combine is an annual event held to evaluate football players. The results of the combine are used to identify talent and player potential. Our study aims to examine the relationship between combine drill performance (e.g., speed, power, agility, explosiveness) and career longevity. We performed a retrospective review of The National Football League combine test results for all defensive players from 2005–2015 to determine the association of each player’s combine test results with career longevity. The position that had the most significant associations for 1-year status was linebackers, with weight, 10-yard dash, 20-yard dash, 40-yard dash, broad jump, 3-cone drill, and shuttle being significantly associated with 1-year roster status. The position that had the most significant associations for 5-year status was cornerbacks, with weight, 10-yard dash, 20-yard dash, 40-yard dash, 3-cone drill, and shuttle being significantly associated with 1-year roster status. The least number of significant associations was found for safeties, with no drill being associated with 1-year roster status and only height and shuttle time significantly associated with 5-year career longevity. Our study demonstrates the utility of the combine results to help estimate the career longevity of NFL defensive players.

Characterisation of the Wear of the Roller Cone Drill Bit Caused by Improperly Chosen Drilling Regime

The rapid drop in the penetration rate or failure of the drill bit during the drilling process delays the drilling process. In our investigation, the ‘in situ’ drilling parameters were monitored during the drilling process along with the roller cone drill bit, which is suitable for drilling in soft rock formations (IADC 136). The drill bit was thoroughly examined to determine its damage and wear occurred during drilling along with decreasing penetration rate. The modern and standardised investigation methods were used to analyse the rock materials and the micro- and macro-structure of the materials of the roller cone bit. The analyses were performed by means of optical and electron microscopes, simultaneous thermal analysis of the steel materials, analysis of the chemical composition of the materials of the drill bit and determination of the geomechanical parameters of the drilled rock. The resulting wear, localised fractures and cracks were quantitatively and qualitatively defined and the parameters were correlated to the drilling regime and the rock material. The results of our investigation of the material of the roller cone bit can serve as a good basis for the development of new steel alloys that can withstand higher temperatures and allow effective drilling without structural changes of the steel material.

Loading of bearing retaining pin of tricone drill bit

Improvement of cone drill bit design is an engineering challenge as it is connected with considerable energy to be transferred via the drill to well bottom in the limited well space. In such conditions, it is difficult to create a full-size bearing assembly, including bearings and lubricating devices, as well as the sufficiently efficient cutting structure of the bits. Moreover, the condition of equal lives of the cutting structure and the bearing assembly is to be fulfilled. The operating practice of tricone drill bits in shothole drilling reveals their low serviceability. The life of a bit ranges from a few hours to a few days subject to physical and mechanical properties of rocks. The main cause of bit failure is damage of the retaining pin shoulder rivet under high contact stresses. Aimed at improvement of cone drill bit design and justification of engineering changes, the stress–strain analysis of the bearing retaining pint is performed, and it is found that the pin shoulder rivet experiences essential contact stresses and bending loads. It is proposed to equip cone drill bits with circulation lubrication system for the bearing assembly. Lubrication improvement can ensure reduction in loading of the bearing assembly components and, consequently, provide higher durability and wear resistance of these parts. The study was supported by the Ministry of Education and Science of Russia according to the state contract with the Ural State Mining University, Contract No. 0833-2020-0007.