Search Results (4)

The instability (in processing time) in the flow-drill screwing process is undesired but inescapable due to variations in material property, gauge, and process parameters. A substantial number of materials and lab labor need to be used to test and control the variability of the real manufacturing joining process. To enhance the stability and efficiency of the screwing process, this study seeks multi-disciplinary collaboration by applying linear-regression modeling. Six hundred and forty-eight data points were collected and split into an 80% training set for model building and a 20% test set for model validation. A multiple linear-regression model was built. The results indicated that, compared to variable base level (6000 rpm rotational speed and 1100 N downforce), higher rotational speed (8000 rpm, 7000 rpm), greater downforce (1200 N, 1300 N), and their interaction were significantly associated with passage (processing) time, while the switch point did not significantly affect passage time. The interaction plot and effect size were adopted to provide measurements of the effect magnitude on processing time. The coefficient of determination indicated that 86% of the variability in the passage time can be explained by this model. Statistical analysis, such as data visualization, statistical modeling, and other data-driven analysis methods, can be used to detect underlying relationships between variables, investigate variations, and make predictions in the manufacturing process. The outcomes from the data-driven analysis can benefit from improving the economical manufacturing system, refining the processing setting, and reducing test material costs, labor, and lead time. Full article

Currently, screw conveyors and negative pressure vacuum screens with negative pressure vibration units are used for handling drilling cuttings both domestically and internationally. However, there is currently no effective solution to address the high liquid content of drilling cuttings during their conveyance by screw conveyors. In this paper, a novel design scheme for a negative pressure spiral separation and reduction device is proposed based on an extensive literature survey. This device aims to effectively reduce the liquid content of drilling cuttings during their conveyance by screw conveyors, thereby minimizing the overall liquid content throughout the drilling process. The structural design of the negative pressure spiral separation and reduction device is conducted using theoretical analysis and 3D solid modeling methods, while strength analysis of the negative pressure suction unit is performed using a finite element method. Additionally, theoretical research on relevant process parameters is carried out, and an online real-time testing system for experiments is designed. An analysis of experimental results demonstrates that within 151 s, the liquid suction rate of the device can reach 51%, with an average flow speed of approximately 0.008 m/s, thus achieving the desired target for drilling cutting separation and reduction. By designing this new negative pressure spiral separation and reduction device, its feasibility has been verified through acceptable engineering results obtained from experimentation; furthermore, it aims to achieve an optimal liquid suction effect for drilling cuttings in order to enhance solid–liquid separation efficiency, as well as to improve drilling fluid recovery efficiency by conserving mud materials and reducing overall drilling costs. Full article

Biotribology is applied to study the friction, wear, and lubrication of biological systems or natural phenomena under relative motion in the human body. It is a multidisciplinary field and tribological processes impact all aspects of our daily life. Tribological processes may occur after the implantation of an artificial device in the human body with a wide variety of sliding and frictional interfaces. Blood is a natural bio-lubricant experiencing laminar flow at the lower screw velocities associated with drilling implants into bone, being a viscoelastic fluid with viscous and fluid characteristics. The viscosity comes from the blood plasma, while the elastic properties are from the deformation of red blood cells. In this study, drilling parameters according to material properties obtained by Finite Element Analysis are given. The influence of blood on the resulting friction between the surfaces is demonstrated and correlated with mechanical and biological consequences, identifying an innovative approach to obtaining a new lubricant parameter for bone drilling analysis. The lubrication parameter (HN) found within the limitations of conditions used in this study is 10.7 × 10⁻⁷ for both cortical bone (D1) and spongy bone (D4). A thermal-structural analysis of the densities of the soft bone (D4) and hard bone (D1) shows differences in only the equivalent stress values due to the differences in respective Young moduli. The natural occurrences of blood as a lubricant in bone-screw perforations are poorly investigated in the literature and its effects are fundamental in osseointegration. This work aims to elucidate the relevance of the study of blood as a lubricant in drilling and screwing implants into bone at lower speeds. Full article

The implementation of a printed circuit board (PCB) drilling machine using recyclable materials and computer-aided control is presented. A mechanical system using a DC motor for movement on the X and Y axes, and a transmission mechanism by belts, pulleys, and a worm screw was made. For the Z axis, a mechanism based on a worm screw, nuts, and a stepper motor was implemented. The main board has two microcontrollers communicating in a master-slave configuration via a serial protocol. A real-time operating system (OSA) was implemented to optimize the data flow to the computer using the USB protocol, for communication with the slave microcontroller, positioning the Cartesian axes, and control the motors. The slave is responsible for monitoring the status of the encoders and limit switches, as well as the information delivery to the master. A Matlab-based user interface was developed to determine the coordinates of the holes to be drilled by processing a jpg image. This also allows the user to control the DC motors using PWM signals via configurable parameters of PID controllers. The end result is a drilling machine which able to operate both manually and via a computer, for drilling PCBs of a maximum size of 24 × 40 cm. Full article