The condition monitoring techniques like acoustic emission, vibration analysis, and infrared thermography, used for the failure diagnosis of bearings, require longer processing time, as they have to ...perform acoustical measurement followed by signal processing and further analysis using special software. However, for any bearing, its period of usage can be easily determined within an hour, by measuring the bearing sound, using sound level meter (SLM). In this paper the acoustical analysis of the spindle bearing of a radial drilling machine was performed using SLM, by measuring the sound pressure level of the bearing in decibels, for different frequencies, while muting all the other noises. Then using an experimental set up, two database readings were taken, one for new bearing and the other for completely damaged bearing, both are SKF6207, which itself is the spindle bearing. From these three sets of sound pressure level readings, the period of usage of the spindle bearing, was calculated using an interpolation equation, by substituting the life of the bearing from the manufacturer’s catalogue. Therefore, for any machine with a SKF6207 bearing, its usage time can be estimated using the database readings and one measurement on that machine, all with the same speed.
Drilling, as the initial stage of exploitation in open-pit mining, has a significant effect on subsequent mining stages. Any failure in a drilling machine stops the drilling operation and, as a ...result, all following operational phases come to a halt. The drilling system is the most important part of the drilling operation. This study selected two new rotary-type drilling machines (A and B) in Sarcheshmeh Copper Mine in Iran as a case study to perform a reliability and availability analysis of their drilling systems. The drilling system was divided into three independent subsystems; drill string, rotary head, and mast. The reliability modeling used a reliability block diagram and Monte Carlo simulation. Reliability and availability were evaluated, and the importance of each subsystem estimated. A preventive maintenance schedule was proposed using weighed reliability allocation to achieve the reliability target. The results show the mast is the most reliable subsystem. Importance measure analysis indicates the drill string and rotary head are the most critical subsystems of machines A and B, respectively. Finally, under the proposed maintenance policy, the reliability of the drilling systems of machines A and B is improved.
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.
Underground mining is a difficult area for miners to work. Miners must go to the working faces by walking, which is not only time consuming but also physically demanding. In mines, a man-rider chair ...lift system (MRCL) has been developed to alleviate the strain stresses caused by walking lengthy and uneven distances up to the working faces. All parameters, including horizontal and vertical distances, variation and inclination of underground mines, slope forces considering the weight of persons and chair, forces acting towards return and drive unit, curves angles, power to operate, and rope safety factor, are calculated mathematically while modelling a man-rider chair lift system for both the installation and extension phases. We analyzed the analytical approach in conjunction with practical installation of the man-rider chair lift system to establish if the installation and extension of MRCL is genuinely feasible in the current scenario. We also created a simulation model of steel wire rope in Creo 8.0 for analyzing the various stresses on it with the Ansys R 16.2 software. In both phase I and phase II, the factor of safety is above that recommended, and the system is a hundred percent reliable, risk-free, and safe for operation.
Rotary drilling machines are the most common machines used for drilling the blast holes in mining and constructions activities. The vital role of drilling operation in mining activities reveals that, ...the performance analysis of drilling machines and their failure and repair behaviors are essential. Therefore, the present study focuses on the reliability, availability and maintainability (RAM) of drilling machines. In this paper, four rotary drilling machines at Sarcheshmeh Copper Mine in Iran are considered for repair and failure data collection. RAM analysis of drilling machines is done using Markov Approach. Results show that the reliability of drilling fleet is decreased by 0.67% in per hour drilling. The hydraulic system is the main unavailability reason of all machines. Moreover, the most failures of the two newest machines are completely repaired in 25 hours.
Inverse kinematics solutions are the basis for position and orientation control of automated machines in their Cartesian workspace. This paper presents an efficient and robust inverse kinematics ...algorithm for a new circumferential drilling machine for aircraft fuselage assembly. After a brief introduction to the circumferential drilling machine and its forward kinematics, the paper discusses the nonlinear optimization method for solving inverse kinematics problems. The objective function is defined as a weighted combination of a position error function and an orientation error function. By representing orientation error as the geodesic distance between two points on a unit sphere, the paper proposes to define the orientation error function by using faithful geodesic distance functions, which are accurate approximations to the geodesic distance when it is small. For increased efficiency, robustness, and easy setting of initial values, the inverse kinematics problem is decomposed into two subproblems. The revolute joint coordinates are obtained by nonlinear optimization, and the prismatic joint coordinates are calculated with closed-form formulas. Numerical experiments show that the objective function defined with faithful geodesic distance functions is effective, and the proposed algorithm is efficient, robust, and accurate. The algorithm has been successfully integrated into the control system of the circumferential drilling machine. Preliminary drilling experiments show that the position accuracy of drilled holes is within ±0.5 mm, which is acceptable for the assembly of large aircrafts.
This article analyzes the application of electrical automation technology based on computer technology in the rocker drill press. The process transformation of the electric control system of the ...radial drilling machine through the electric automation technology not only improves the reliability and anti-interference ability of the electric control system of the radial drilling machine, but also reduces the probability of occurrence of failure of the radial drilling machine and the maintenance workload. The introduction of control technology into the electrical control system of the radial drilling machine can further realize the intelligence and automation of production. The following article aims at the electrical control requirements of radial drilling machines, and then introduces the transformation system based on automation control technology.
Laser micro drilling is a non-traditional machining process for producing micro hole of various sizes and different angle in many modern industrial application, such as aerospace gas turbine, ...automobile industry, electronics field etc. Laser drilling is extremely high speed with high aspect ratio. However, the quality and accuracy of the holes can be excellent, if the optimal process parameter has set. It is difficult to achieve exact size of hole as per suggested by the equipment manufacturer without any consideration. So this paper addressed to investigate influence of process parameter on drilling characteristics of 304 stainless steel of 1.5 mm thickness material using Nd:YAG laser drilling through desirability function optimization technique. The effect of process parameter taken during machining operation is average power, nozzle stand-off, nitrogen gas pressure to obtain requisite hole quality. The output responses are entry circularity, exit circularity and taper angle were considered performance criteria for the experimentation. Analysis of variance (ANOVA) has been performed to find out the significant process parameter during the micro drilling process. It is found that nitrogen gas pressure is highly influencing factor on the overall response characteristics, which is about 54.62% and nozzle standoff is 2nd highest influencing parameter, which is about 27.69%.
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