Dynamic modeling and experimental investigation of hole making accuracy in the helical milling process

Helical milling is one of the novel hole-making methods to create a hole with high accuracy and quality. In this study, the helical milling process is dynamically modeled using a set of second-order differential equations. In this modeling, the tool is considered a cantilever beam with a degree of freedom in all three directions of x, y, and z. Experimental tests were conducted to investigate the validity of the obtained theoretical relations and the effects of different parameters such as material, diameter, and rotational speed of the cutting tool on the precision of the created hole. The error of the theoretical relations in predicting the hole diameter is 2.7%, indicating the high precision of the accomplished modeling. Theoretical relations show that the error of the chip removal path decreases by increasing each of the parameters, namely, tool stiffness, the rotational speed of the tool, tool diameter, and tangential feed per tooth. In contrast, the error of the chip removal path increases by increasing each of the parameters, namely, the speed of the tool in the helical path and axial feed per tooth. It has been shown that improving the cutting tool material in terms of strength or increasing the rotational speed of the tool and the cutting tool diameter causes a reduction in the diametrical error. It has been shown that the diametrical error rate is 0.9% with the change of the cutting tool from HSS-E to carbide, and it has reduced to 0.6% by increasing the rotational speed of the tool from 900 r/min to 2100 r/min.

An Experimental Study on Electrosparking of Tool Electrode Forced Cooling Based on Micro Heat Pipe Bundle

An electrosparking experiment of ASP30 powder metallurgical steel was carried out through tool electrode forced cooling based on micro heat pipe bundle by using the semiconductor encapsulation mould. Results demonstrate that the micro groove formed among sintered copper fibers based on wick of micro heat pipe and the unique composite structure of the surface chopped morphology can not only increase capillary pressure of the wick, but also strengthen evaporation/condensation process at two ends of the micro heat pipe, and improve cooling effect of micro heat pipe to tool electrode significantly. Compared with traditional electrosparking, electrosparking of tool electrode forced cooling based on micro heat pipe bundle increases the inter-electrode cooling, chip removal and deionization of electrosparking and further lowers tool electrode loss by strengthening heat dissipation of tool electrode. Hence, it can improve stability of electrosparking, increase pulse utilization and increase the processing speed and processing surface quality significantly.

Numerical Calculation of Grinding Wheel Wear for Spiral Groove Grinding

Due to its good cutting performance in titanium alloy machining, integral end mills are more and more used in machining aero-engine impeller blades. The tool spiral groove plays the role of chip acceptor and chip removal, and the accuracy of its parameters has an important effect on the cutting performance. In the grinding process of the spiral groove, the grinding wheel's external grinding is mainly involved in the grinding task. The grinding wheel's wear degree is related to the grinding time and grinding times of the grinding wheel, and the wear of the grinding wheel will lead to the change of the parameters of the spiral groove. To achieve the accurate solution of the grinding wheel surface wear profile, image processing technology was used to extract the spiral groove end section contour coordinates of the grinding wheel and fit them. The worn sand profile was solved based on the contact line principle, and the grinding wheel wear amount was obtained. The traditional reconstruction method was used to verify the algorithm. The results show that the accuracy of the reverse algorithm for the wear profile of the grinding wheel is relatively high.

Research on variation law of geophysical drill-bit downhole flow field under the interaction of multiple hydraulic factors

Mountain geophysical prospecting operations play an important role in the entire petroleum exploration field. Geophysical drill-bit is the main tool for mountain geophysical prospecting operations. Its hydraulic structure directly affects the downhole flow field and then affects the chip removal efficiency and drilling efficiency of the bit. At present, most of the scholars’ research is focused on Poly Diamond Crystalline bit, roller bit, etc., and the research on geophysical drill-bit is less, and most of them study the downhole flow field based on the change of single hydraulic structure. The primary objective of this research is to study the variation law of the downhole flow field under the interaction of multiple hydraulic structure factors. The drilling time and cuttings size of two geophysical drill-bits with different hydraulic structures are compared, and the key hydraulic structure factors are selected for analysis. Using numerical simulation software, take different levels of key hydraulic structure parameters and carry out orthogonal experiments. Under the interaction of various factors, study the flow field distribution in the flow channel, the downhole, and the annulus area of the shaft lining. The hydraulic structure of the geophysical drill-bit is closely related to the drilling speed and chip removal efficiency. When multiple hydraulic factors are changed, the diameter of the flow channel is the best when it is 10–12.5 mm, the inclination of the flow channel should be set as close as possible to the center of the downhole, and the length of the chip groove increases, the movement of cuttings is more stable. Variation law of downhole flow field under the interaction of multiple hydraulic factors is studied. This study provides a basis for the hydraulic structure design and optimization of the geophysical drill-bit.

Design of Internal Flow Passage of Internal Chip Removal Drill for Suction Type Internal Chip Removal System

Aiming at the current problem that the cutting chips cannot be automatically recovered in the hole-making process of carbon fiber reinforced resin matrix composites, This article first introduces a new type of drilling chip removal technology system-suction type internal chip removal system, which can timely and effectively discharge the powdery chips generated in CFRP hole processing during cutting; Secondly, in view of the problem of the internal runner design of the internal chip removal drill used in the system, this article conducted the following research: 1) Based on cutting experiments and statistical methods, classify the chips produced in CFRP hole making, and give the chip distribution rules; 2) Secondly, on the basis of fluid mechanics, using FLUENT simulation method, on the basis of defining the center distance and center angle of the inner runner for the design of the internal chip removal drill bit, the center distance and the center angle of the inner runner are given. The influence law of the chip removal center angle and the cross-sectional shape of the internal runner on the chip removal effect of the tool internal runner; 2) Based on fluid mechanics, using FLUENT simulation method, on the basis of defining the center distance of the inner runner and the center angle of the inner runner, the center distance of the inner runner, the center angle and the cross-sectional shape of the inner runner are given to the tool The influence law of the chip removal effect of the internal runner; Finally, a suction type internal chip removal system was built, and the experimental method was used to verify the correctness of the internal runner design of the internal chip removal tool.

Experimental Investigation and Optimization of Delamination Factors in the Drilling of Jute Fiber Reinforced Polymer Biocomposites with Multiple Estimators

Currently, the manufacture of composite structures often requires material removal operations using a cutting tool. Indeed, since biocomposites are generally materials that do not conduct electricity, electro-erosion cannot be utilized. As a result, the processes that can be used are limited to conventional machining, called chip removal machining, such as drilling. Delamination factors are widely recognized for controlling the damaged area (delamination) induced by drilling in industry. As discussed in the literature, several approaches are available to evaluate and quantify the delamination surrounding a hole. In this context, the objective of this study is to compare the three Fd evaluation methods that have been most frequently used in previous investigations. To this end, three rotational and feed speeds and three BSD tool diameters were selected (L27) for drilling 155 g/m2 density jute fabric reinforced polyester biocomposites. The response surface methodology (RSM) and artificial neural networks (ANNs) were applied to validate the results obtained experimentally as well as to predict the behavior of the structure depending on the cutting conditions.