Papers by Keyword: Drilling

Abstract: Accurately grasping the distribution of different rocks can achieve the minimum explosive consumption and meet with the requirements of blasting quality; Not only reduces the cost of blasting, but also improves the safety and controllability of blasting. By utilizing the physical reactions to different rocks in the rigs process, the manual assisted learning process of the rig and the two stages of automatic drilling are proposed; After the automatic drilling, the lithology distribution of the borehole can be obtained in real time. The automatic drilling is the key to achieving fine blasting. Combined with the research of specific rigs and data processing methods. A KNN recognition model is established to construct the relationship between various indicators and lithology under certain confidence conditions, and this method can achieve automatic real-time adjustment and control of drilling parameters.

Abstract: Adaptive feed-rate controlled (AFC) drilling has been proposed as a high-quality and highly efficient drilling method for thermoplastic resins. The feed rate of the drill tool is controlled by the load in the thrust direction during AFC drilling. In the early stages of AFC drilling, the drill feed rate is extremely low, followed by a sudden increase in the drill feed rate. Experimental investigations revealed that the temperature near the drilling point had a dominant effect on the position at which the drill feed rate transitioned from low to high. The feed-rate transition temperature was approximately 150 °C for PA6. Therefore, the feed-rate transition position accelerated as the spindle speed increased, which significantly affected the cutting temperature. After the feed rate transitioned to a higher speed, drilling progressed at a constant rate. Additionally, the temperature of the drilled hole was generally constant regardless of the hole depth. One of the applications in which AFC drilling is expected to be superior is the drilling of different stacked materials. The effectiveness of AFC drilling was examined and compared with general constant-feed drilling for a stacked material of PA6 and carbon-fiber-reinforced thermoplastics. When the drilling efficiency was aligned, the maximum thrust force during AFC drilling was suppressed to less than 50% of that during general constant-feed drilling. Furthermore, the finished inner surface of the drilled hole was better after AFC drilling.

Abstract: A mechanical work piece created industrially frequently contains more than one machining process. Furthermore, it is a common activity of programmers, who make this selection every time a milling and drilling operation is conducted. Tool wear and borehole quality are two essential challenges for high precision drilling procedures, with Al 356 alloy being employed in experimental planning. Drilling specifications will be assessed in this work to get optimal parameters in minimizing the influence of drilling damage on alloy using a swarm-based optimization model. The drilling parameters are optimized using the Bacterial Foraging Optimization (BFO) method, which includes three control factors: depth, feed rate, and spindle speed. Each parameter is designed in three levels, with multiple performance characteristics such as thrust force, surface roughness, and delamination factor. This investigation was carried out in order to obtain the proper optimization. The feed rate, next to the spindle speed, was discovered to be the essential element inducing lamination in drilling, with this phenomenon occurring in each diameter of the drill bit. The results reveal that the feed rate and drill type are the most important parameters influencing the drilling process, and that employing this strategy can successfully improve drilling process outcomes.

Abstract: Drilling equipment is the main asset of mining companies; therefore, a decrease in the operability and availability of such equipment can generate negative impacts on organizations, such as the generation of extra expenses due to the hiring of third parties for the performance of activities and contractual projects. According to statistics from previous studies, the availability of equipment in the sector should be 95% to be considered optimal for use in mining operations. Equipment downtime can be avoided by establishing and following a preventive maintenance schedule and having spare parts and hydraulic components readily available for maintenance. The purpose of this work is the implementation and follow-up of a maintenance management plan based on a failure mode analysis and autonomous maintenance and preventive maintenance with the purpose of keeping the equipment in optimal conditions, maintaining an adequate level of availability and extending the useful life of the assets. With the simulation of the Arena program, a possible availability of 95% was evidenced, which corresponds to being adequate for the optimal operation of the equipment and the continuity of the projects.

Abstract: One of the most important issues in the procurement of parts and products by the process of metallurgy is the design of the details of the press-mold. The design should be carried out in such a way that the additional mechanical processing of the purchased parts and products is minimal. The tooling and technological scheme of the press-mold should be selected as might it be economically viable and the mechanical processing stakes are small. For these purposes, in this present study, the valve part of the high-pressure drilling pump НП-720х105, which is widely used in the oil and gas complex, was selected for theoretical and experimental investigations. With the help of the software, in order to ensure equal distribution of residual porosity in the samples, the optimal size and configuration of the samples were determined, and the inner and outer conical walls of the asymmetric samples were subjected to dynamic hot pressing. "Valve seat" and "valve tray" of the НП-720х105 high-pressure three-plunger pump were used for the experimental studies. From the conducted tests, it became clear that during the preparation of abrasive steels with high impact-abrasive corrosion resistance, it is necessary to thoroughly study the chemical and granulometric composition, structure, and strengthening process. Theoretical and experimental results show that the technology of manufacturing parts resistant to impact-abrasive corrosion allows the obtained parts to work in conditions of high impact-hydroabrasive corrosion.

Abstract: Recently, the use of carbon fiber-reinforced plastic (CFRP) has been picking up in aerospace and automotive industries. However, machining of CFRP produces fine cutting chips, which disperse in the machining environment and can be hazardous to workers and machine tools. Therefore, a cutting-chip disposal technology is required to address this problem. This study investigated the chip dispersal behavior during the drilling of CFRP to identify the factors that affect the dispersal of cutting chips. The focus of this study was the airflow field generated by drill rotation. Therefore, a simulation analysis for around the drill edge was used. The results of the drill edge simulation and chip discharge behavior during CFRP drilling were validated experimentally. The results suggested that the airflow field around the drill edge caused by drill rotation did not significantly affected chip dispersal.

Abstract: The application of basalt fiber reinforced composites has increased in recent years. However, its behavior during machining processes remains to be studied in depth, as drilling operations. The objective of this paper is to analyze the circularity of the holes at the exit of the drill in these composites. The laminates were obtained through basalt fiber fabrics and epoxy resin, with application of pressure and heat to achieve the final prepregs. These basalt fiber-epoxy laminates were used in experimental tests and drilled under different cutting conditions and three types of drill bits. The quality of the holes was measured through the outlet diameters, and thus determining the circularity of the holes. A three coordinate measuring machine was used in this process. Moreover a General Linear Model has been estimated, obtaining a coefficient of determination of 86.5%. The results have indicated that the drill bit type and its rotation speed are significant factors. Moreover, the outcomes have allowed to select a suitable type of drill bit, to limit the cutting conditions, and to identify the influential points, conditions that have provide undersized and oversized diameters.

Abstract: Composite structures, such as glass fiber reinforced polyether-ether-ketone (PEEK) and polyamide (PA66), usually undergo drilling operations for subsequent assembly. A typical problem with these composites is damage around the drilled surface due to a possible non-homogeneous cutting of the fibers. In this context, the delamination is evaluated after a cryogenic drilling. Thus, the objective of this paper is to determine the feasibility of cryogenic drilling considering surface damage after cryogenic machining, at hole the entry and exit. Experimental test were carried out in a machining center at a temperature close to -130 °C using liquid nitrogen, LN₂, as cooling environment. The diameter of the drill is 6 mm and the drill tip is polycrystalline diamond (PCD). The plate material is PEEK-GF30 and PA66-GF30. The delamination factor was obtained using a three-dimensional measurement device with an optical sensor and a focus-variation device. The results obtained are favorable regarding the potential use of cryogenic machining.

Abstract: The use of advanced materials in new fields of applications is usually related with specific properties and great advantages. However, it may become an important technological challenge for the manufacturing and joining of these materials. Carbon Fiber Reinforced Plastic (CFRP) is widely used in aerospace or automotive industry, but currently is starting to be used as structural component in the building industry. In contrast to the thin parts developed for aircraft. the elements for construction are characterized by high thicknesses. This fact increases the abrasive effect of carbon fibre on cutting tools when it is machined by conventional processes. For this reason, non-conventional technologies. as Abrasive Water Jet Machining (AWJM), could be a suitable technology for this purpose. An operation of great interest for these materials is drilling. The industry demands the drilling of a wide range of increasingly large diameters. This, in combination with large thicknesses in CFRP, makes the machining process more difficult. Technologies such as orbital drilling are limited by the range of diameters that can be obtained and the abrasive wear between the material and the cutting-tool. Therefore, the use of abrasive waterjet cutting is proposed as an alternative technology capable of machining diameters in a wide range. One of the main limitations for the use of AWJM on large thickness parts of CFRP comes from the surface finish of the machined surfaces. where high values of roughness can be found. In this research, the effects of water jet cutting parameters have been evaluated for the machining of 17 mm thickness CFRP specimens. By variations on the traverse speed. abrasive mass flow rate and hydraulic pressure. differences in the performance and micro-geometrical characteristics of the machined surfaces were obtained, allowing to identify most significant affecting parameters of the process.

Abstract: Drilling of metal alloys is an operation that is still performed today in many industrial sectors such as aeronautics, automotive or civil engineering. This is mainly due to the high number of mechanical joints that must be made in structural elements. However, it is known that conventional drilling operations can generate defects on the machined surface mainly due to the effect of temperature on the tool and the material. For this reason, a non conventional process such as abrasive water jet machining (AWJM) is ideal for this type of operation. The decrease in temperature along the process minimizes the defects generated while keeping a high surface finish on the machined part. Therefore, this research has been carried out, where a 2 mm thick S275JR steel has been drilled by abrasive water jet. An experimental methodology has been developed to carry out the drilling. The input parameters include hydraulic pressure (P), stand of distance (SOD), abrasive flow rate (AMF) and traverse speed of the tool head (TS). In order to carry out the experiment satisfactorily, micro-drilling trials have been carried out leaving the TS parameter fixed in order to know the behavior of the material against the kinetic energy presented by the water jet equipment. These holes have been analyzed by means of the geometrical defects obtained in the form of diameter and kerf taper angle. Finally, the most relevant conclusions of the research have been developed, where it is emphasized that kerf taper (KT) angle increases drastically with the increase in SOD, giving greater results in area and with a greater amount of deformations and projections.