High Speed Feed Research Articles

Mixing effects of high-speed jets in gas-solid riser and downer reactors

For the high-temperature and short-contact time gas-solid reaction process, riser and downer are considered appropriate reactors. To realize an intensive and complete mixing of reactants with catalysts, the feed raw is always introduced in the form of high-speed jets. In this study, in order to investigate the mixing effects of different types of high-speed jets in riser and downer, traceable ozone is injected with the high-speed feed jets to react with catalyst particles. By detecting the decomposition of ozone, the gas-solid mixing and reaction in riser and downer under the influence of both co-current and counter-current injections are analyzed. The relative ozone concentration is used to reflect the location reaction extent and its radial nonuniformity index is proposed to compare the results in riser and downer. It is found that the jet influence zone in downer provides a relatively better environment for the mixing of feed jets with catalysts. In the riser, introduction of counter-current injections could improve the uniformity of gas-solid mixing in the initial contact region of feed with catalysts.

Ultrasonic-Assisted Grinding of Microholes Using Ultrasmall-Diameter Cemented WC Tools

Although grinding is a widely employed method for hard and brittle materials, drilling microholes requires the use of an ultrasmall-diameter grinding wheel that is difficult to fabricate and breaks easily when grinding force is applied, resulting in a high tool cost. To solve this problem, cemented WC micropins were fabricated by electrical discharge machining, and microholes were drilled using them as micro-grinding tools with the assistance of ultrasonic oscillation. The micropin tools can be employed in grinding because the convex parts of the electrical discharge craters formed on their surfaces serve as cutting edges of abrasive grains in grinding wheels. To clarify the drilling conditions necessary for ultrasmall-diameter tools to drill holes with a diameter less than 5 µm, the relationships between drilling conditions and drilling characteristics were investigated. The drilling conditions included the tool rotation speed, tool feed speed, ultrasonic oscillation amplitude, and use of grinding fluid. The drilling characteristics included the hole diameter and grinding force evolution. The investigation showed that a high tool rotation speed prevented the increase in the grinding force because of the faster grinding speed. A low tool feed speed was favorable to lower grinding force. At a high tool feed speed, most likely, the tool was fed before the workpiece material was sufficiently removed, thereby exhibiting a large grinding force. The ultrasonic oscillation amplitude had no noticeable effect on the grinding force. The hole diameter was not affected by the tool rotation speed, tool feed speed, or ultrasonic oscillation amplitude. Although the use of grinding fluid reduced the grinding force, the hole diameter increased, probably because enhanced lubrication caused the tool to slip on the workpiece surface at the beginning of drilling, resulting in an increased rotational runout. Under the favorable conditions obtained, a hole of 3.2 µm in diameter was successfully drilled in crown glass.

The effect of staged process parameters for flow drill screws on the strength of the connection between carbon fiber-reinforced plastic and aluminum alloy

This article applies flow drill screws (FDS) technology to the connection of dissimilar materials, carbon fiber-reinforced plastic (CFRP) and 6061-T6 aluminum alloy (AA6061-T6), and proposes a method to study the influence of FDS process parameters on the strength of the connection in stages. Based on this method, the optimal process parameters for the connection of this type of plate are explored. Firstly, the mathematical analysis of the process in each stage is conducted, and then the different process parameters in different stages are grouped and tested for the strength of the joint. The optimal process parameters obtained from the previous stage are input into the next stage for further testing, resulting in the highest shear connection strength of 5.98 kN for the FDS connection of CFRP and AA6061-T6 plates. The experimental results show that the influence of different process parameters on the strength of the joint varies in different stages. To improve the connection strength, high speed and low feed force should be selected in the second stage, low speed and low feed force should be selected in the third stage, and the tightening torque should be reasonably selected in the fourth stage.

Optimizing the input parameters setting for least hole defects while drilling CFRP laminates by multi-objective optimization on the basis of ratio analysis (MOORA) method

Carbon fiber reinforced plastic laminates have been kept under the category of hard-to-machine materials despite having some unmatchable properties like high strength, stiffness, corrosion resistance, etc. The heterogeneous nature of the material makes the essential secondary machining process a challenging task to perform. Drilling is always considered the effective way to drill holes necessary for the assembling purpose in structure building. Though, drilling the CFRP laminates critically affected by the abrasiveness of the reinforcing fibers eventually produces various defects. In this particular experimental analysis, a decision-making model associated with the Multi-objective optimization of ratio analysis (MOORA) method has been used in selecting the best possible parameter setting for minimizing defects. The results suggested that this method is found to be effective in solving the real-world problem of selecting the optimized parameter setting in drilling CFRPs. The best possible combination of low point angle, high speed, and low feed rate produces the least drilled hole defects.

Various HFCVD diamond coatings synergistically tuned using CH4 gas flow and working pressure and key merit evaluation of their coated tools

Diamond-coated tools can meet the service requirements of high precision, high efficiency and long life with multi-element coupling, but the milling characteristics of graphite materials with high spindle speed, feed speed and high force may require tools with a high number of micro-edges and good adhesion strength. In the present study, microcrystalline diamond (MCD), nanocrystalline diamond (NCD) and gradient composite diamond (GCD) coatings were deposited on commercial end mills subjected to distinct CH4 gas flows and working pressure by hot filament chemical vapor deposition. The adhesion strength, erosion resistance and milling performance of the diamond coatings in milling graphite materials were evaluated. Besides, the effect of CH4 gas flows and working pressure on the growth model of diamond coatings and the mechanism of crack propagation when subjected to stress concentration were studied. The results show that the combination of high CH4 gas flows and low working pressure achieves the re-nucleation of diamond particles, the smaller grain, more graphite/amorphous carbon in the boundaries and larger residual stresses lead to continuous crack propagation, causing poor adhesion strength, erosion resistance and milling performance in NCD and GCD coatings. Conversely, the low CH4 gas flows to ensure the epitaxial growth required for MCD coating, the larger grain, higher diamond purity, columnar structure and smaller residual stresses allow the pinning effect between coating and substrate, altering and increasing the path of crack propagation, making it suitable for milling conditions with high speed and high force. This study provides significant insights into the links between diamond morphology, structure, grain size, boundaries, and phase composition and the mechanical properties of adhesion strength, erosion resistance, and milling properties by synergistically tuning or alternating the CH4 gas flows and working pressure.

Research on look ahead control of contour error for casting sand mold with five-axis linkage high speed machining

Casting sand mold with five-axis linkage high speed machining has the characteristics of high feeding speed, small milling force, fast tool axis swing speed and big contour error. The coupling relationships among tool axis swing, following error and contour error were analyzed, the computing method of axis movement speed for five-axis linkage machining was proposed, and a rapid linear estimation model of contour error for casting sand mold with five-axis linkage machining was established. On this basis, according to the relationships between rotary axis speed and tool axis swing speed, a look ahead self-adaptive control method of contour error for casting sand mold with five-axis linkage high speed machining was proposed, and an experiment of impeller sand mold with five-axis linkage machining was carried out. The results show that the contour error formed by tool tip can be estimated rapidly according to the tool axis swing speed in the process of casting sand mold with five-axis linkage high speed machining, and the proposed look ahead control of the rotary axis speed is an effective method for contour precision of casting sand mold with five-axis linkage high speed machining.

Study on molten pool dynamics and hump formation mechanism in laser wire feeding additive manufacturing

The mechanism of the hump formation during the laser wire feeding process has been investigated in this paper. A numerical model was established to analyze the heat transfer and melt flow of molten pool during process with or without hump formation. And effects of laser power, traverse speed, and wire feeding speed on hump formation were also investigated through such a numerical model. The results showed that, under the condition with high wire feeding speed, the molten metal flowed rapidly to the tail of the molten pool due to the impact force of droplet and the metal vapor recoil pressure. Simultaneously, due to the high speed of laser movement, the thin channel of the trough solidified prematurely under the effect of surface tension, which isolated the heat transfer of the molten pool, and then formed periodic humps. By comparative analysis, the numerical simulation results were in good agreement with the experimental results.

The Damping Effect of Particle-Filled Hollow Sphere Structures and their Application in Machine Tool Components

High speed feed axes are a key for increasing the productivity of machine tools. It requires high acceleration and causes jerk, which excites the machine structure and negatively affects the process quality. One approach to reduce those machine vibrations are passive dampers such as particle-filled hollow spheres (PHS). PHSs dissipate vibration energy through relative motion and friction between particles among themselves and the sphere. Compounds of PHS as core of sandwich materials allow structure-integrated damping of machine tool components and for maintaining a high specific stiffness at the same time. The complex interactions within each sphere lead to nonlinear damping. As of today, precise predictions on how PHSs influence the overall machine behavior are not possible. This prognosis is essential for establishing the material in any machine structure. The paper investigates the damping properties of PHSs in a spindle box of a machine tool. The experimental and numeric analysis demonstrates the nonlinear behavior and shows the reaction of the spindle box under external excitation. The result shows that the damping of the spindle box with PHSs is frequency and amplitude dependent. The damping of PHSs is domain with increased parts of them deformed during vibration.

Intelligent computational of Experimental Study of Intermittent Feed High-speed Grinding Method utilising PSO basis FEM Solver

ABSTRACT The high-speed grinding and polishing machine can not only significantly increase the performance of grinding but also improve the consistency of processing effectively. It is one of the most significant guidelines for the advancement of grinding technology today. Since the high-speed grinding technology has been booming these days, this study develops intermittent high-speed grinding technique for feed which has been under the basic high-speed grinding process. Using a simple list of a straight line, a piece of work can be easily retreated and fed. By affordable arrangement distance of feed-in single grinding, time of action on grinding work piece and grinding wheel has been reduced, it will affect the process of grinding heat sending that does not get fixed sate, it was decreasing grinding temperature at the time of single grinding, the surface temperature was freezer to the closed room temperature throughout the room. The lower grinding temperature was achieved according to this path. The simulation study and experiment were performed on TC4 titanium alloy materials in intermittent high-speed feed grinding, and critics of grinding elements considered grinding temperature along with grinding force have been implemented as end production using finite element analysis of the particle swarm optimization (PSO) basis.

Study on droplet transition behavior, bead geometric characteristics and formability of wire + arc additively manufactured Inconel 718 alloy by using CMT MIX+ Synchropulse process

In this paper, the droplet transfer behavior, geometric characteristics of weld bead and formability of CMT MIX + Synchropulse (CSP) wire + arc additively manufactured Inconel 718 alloy under high wire feeding speed are studied. The results show that a CSP cycle is composed of a CSP high-frequency pulse stage (CSP–HFP) and CSP-CMT stage, and the periods ratio is about 1.7:1. The high frequency and large average welding current of CSP-HFP increase the arc force, which further increases the droplet impact force on the molten pool. The molten pool is significantly deformed, resulting in the penetration depth of the CSP weld bead (1.8 mm) apparently higher than that of CMT (0.5 mm). The surface of the CMT-WAAM sample is more rough and irregular. The large penetration depth provides sufficient support for the molten pool, which promotes the overall stability of the molten pool. The increase of the droplet impact and arc forces enhance the convections in the molten pool, which finally suppresses the overflow phenomenon.

Using HSM Technology in Machining of Thin-Walled Aircraft Structures

Abstract Subtracting manufacturing technologies have entered that realm of production possibilities which, even a few years ago, could not be directly adapted to direct production conditions. The current machines, i.e. heavy, rigid cutting machines using high spindle speed and high feed speed, allow for manufacturing very thin and relatively long parts for use in the automotive or aerospace industry. In addition, the introduction and implementation of new 70XX aluminium alloys with high strength parameters, as well as monolithic diamond cutting tools for special machining, have had a significant impact on the introduction of high-speed machining (HSM) technologies. The main advantage of the applied manufacturing method is obtaining a very good smoothness and surface roughness, reaching even Sz = 6–10 μm and Sa <3 μm, and about four times faster and more efficient machining compared to conventional machining (for the beam part). Moreover, fixed and repeatable milling process of the HSM method, reduction of operational control, easy assembly of components and increase in the finishing efficiency compared to other methods of plastic processing (forming) are other benefits. The authors present a method using HSM for the manufacturing of aircraft parts, such as the chassis beam at the front of a commuter aircraft. The chassis beam assembly is made of two parts, front and rear, which – through a bolted connection – form a complete element replacing the previous part made using traditional technology, i.e., cavity machining, bending and plastic forming. The implementation of HSM technology eliminates many operations related to the construction of components, assembling the components (riveting) and additional controls during construction and assembly.

Characterization of Thrust Force, Temperature, Chip Morphology and Power in Ultrasonic-assisted Drilling of Aluminium 6061

In this study, a special resolution V design and response surface methodology (RSM) were used to characterize the ultrasonic-assisted drilling (UAD) process of aluminum 6061. This characterization was done through developing mathematical models to study the effect of ultrasonic and drilling parameters including spindle speed, feed rate, and amplitude on thrust force, temperature, chip morphology, and power. The tests were done using an industrially hardened non-rotating UAD system mounted in a CNC turning center. The analysis of variance (ANOVA) was used to find significant parameters of thrust force, temperature, chip morphology and power. Then, for all responses, the optimum drilling parameters that provide desired solutions for all responses were obtained. This was followed by out-of-sample testing to verify the accuracy of the developed models. The results of this study showed that in UAD of aluminum, the minimum values of thrust force and chip size were obtained at low spindle speed, low feed rate and high amplitude. The results also showed that amplitude was not a significant parameter affecting the tool temperature and cannot be used to analyze the effect of ultrasonic vibrations on generated heat during UAD. Instead, the interaction of amplitude and feed rate was significant and should be considered in the analysis. Finally, minimum consumed power, specially at higher amplitudes, can be obtained using high spindle speed and low feed rate.

Study on cutting force of reaming porcine bone and substitute bone.

Accurate mechanical feedback systems are critical to the successful implementation of virtual and robotic surgical assistant systems. Experimental measurements of reaming force could further our understanding of the cancellous bone reaming process during hip arthroplasty to help develop surgical simulators with realistic force effects and improve the protection mechanism of robot-assisted surgical systems. In this study, reaming experiments with natural bone (porcine femur) and a bone substitute (polyurethane blocks) were performed on a CNC lathe. This paper proposes using the maximum reaming force of the steady reaming stage to represent the force characteristic. The reaming force is biased to one side in the overlap direction and the maximum reaming force will vary when the reamer is not coincident with the long axis of the bone. The diameter of the reamer has the greatest influence on reaming force, which clearly increases with increasing reamer diameter. During operation, a medium rotation speed and high feed speed can reduce the reaming force. After cutting, the morphology of the cut surface is not flat, but arc-shaped, which will have a significant impact on implantation of the femoral prosthesis. In in vitro cutting experiments, polyurethane blocks can be used as a substitute for cancellous bone.

A Bat Optimized Reliable Elm (Bore) For an Efficient Throughput of Cap-VLC System

Indoor Visible light communication (VLC) is considered one of the most famous communication technologies in today’s industrial life, showing importance in data broadcasting and glowing instantly with the cost-effective source of light-emitting diode (LED). This kind of high-speed network’s properties is controlled by the source device’s shortened bandwidth (LED). Therefore, it is considering highly efficient modulation technique and extreme adaptive demodulation technique for better data rate in visible light communication. Carrier less amplitude-phase (CAP) modulation is an eminent modulation scheme that increases implementation ease and places good position inefficiency. Somehow, the CAP-VLC system’s impact is signal jamming, poor sensitivity, scattering, and noise issues. To overrule this problem, it witnesses the implementation of VLC system with CAP modulation using advanced neural network system of High-Speed Feed Forward Neural Network, which works based on the principle of Extreme Learning Machine (ELM). The same is adopted and extended using the BAT algorithm. Along with this, algorithm optimization technique has been integrated to enhance the entire CAP-VLC system’s performance. Altogether, it can be named as bat-optimized reliable ELM (BORE). The proposed new learning-based algorithm for CAP-VLC has shown better performance in received power distribution of 90.6% at various modulation indexes, better BER of about 97.6% in the voltage level of 3V, and different distances between transceivers, respectively.

Sawing characteristics of diamond wire cutting sapphire crystal based on tool life cycle

Diamond wire saw cutting technology has been widely used in the slicing of sapphire crystal. The ultra-high hardness of sapphire makes the sawing characteristics of diamond saw wire constantly change. At present, there is a lack of in-depth understanding about the influence of sawing characteristics on the quality of sapphire as-sawn wafer, which leads to the unreasonable matching between the process parameters and the sawing characteristics of the saw wire, and reduces the as-sawn wafer quality and the saw wire life. In this paper, the slicing sapphire crystal experiment was carried out with constant process parameters and the variation of saw wire bow angle, nominal diameter and saw kerf loss, surface morphology and surface roughness of the as-sawn wafer during the whole life cycle of the saw wire from initial cutting to breakage was studied. The evolution mechanism of wear and sawing characteristics in the whole life cycle of saw wire was explored, and a reasonable processing scheme which can match the sawing characteristics was put forward. The research results show that in the whole life cycle of the saw wire, the abrasives emerge from the plating layer in turn, then the cutting edge are blunted, and finally the abrasives are greatly flattened and a small amount of falling off. Saw wire has experienced initial wear, stable wear and sever wear, and the proportion of three stages in the whole life cycle is about 0.3: 0.6: 0.1. Compared with the initial stage of wear and the late stage of rapid wear, the saw wire has higher sawing characteristics and better as-sawn wafer quality in the middle stable wear period. The sawing characteristics of new saw wire is relatively weak at the beginning of cutting, so the feed speed of workpiece should be increased gradually from low to high; When most of the abrasives finish sharpening edge, a relatively stable and high feed speed can be adopted; When the abrasives are obviously flattened or fall off, the feed speed should be decreased to accommodate the significantly reduced. cutting performance of diamond saw wire.

Effect of Surface Finishing on Microstructure and Corrosion Behavior of Friction Stir Welded Joints For Dissimilar Aluminum Alloys (AA2024-T3 with AA6061-T6)

The aim of this work is to study the possibility of joining two plates from aluminum alloys, AA2024-T3 with AA6061-T6, using friction stir welding (FSW) technique. In this study, the plates were prepared by cutting with dimensions (100 x 50 x 5) mm by CNC milling machine with cutting speed of 1200 rpm and variable feeding speed of (25, 30, 35 & 40 mm/min). The FSW was operated by a vertical milling machine at a rotary speed of 930 rpm and linear welding speed of 30 mm/min to obtain welding joints of dissimilar plates. Microstructure, surface roughness and micro-hardness were examined. Corrosion test was also carried out by electrochemical methods for all specimens in 3.5wt % NaCl solution, and the corrosion rate was calculated by Tafel extrapolation method. The obtained results demonstrated that the feeding speed has a significant effect in decreasing the corrosion rate comparing with the base metal due to the plastic deformation that occurs at high feed speed. The decrease in surface roughness provided more connected between the two contact surfaces that contributed in the refinement of the microstructure. The sample welded at feed speed 40 mm/min offered the optimum results.

Surface texture generation using high-feed milling with spindle speed modulation

This paper presents a new surface texturing technique using ball-end milling with high feed speed and spindle speed modulation. The ratio between feed-rate and cutting tool radius is in the range of 0.2–0.4, which is much larger than the ratio in conventional milling. Sinusoidal modulation signal is added, so the spindle speed becomes time-varying in order to generate different texture profiles. The cutting tool kinematics are modeled considering the tool-tip run-out and deflection due to cutting forces. The effects of amplitude and frequency of the modulation signal on tool-tip trajectories and surface textures are simulated and analyzed. The relationship between the micro features of the surface texture and the process parameters are investigated. Surface texturing experiments are conducted based on the proposed technique, and tribology tests are performed on the textured surface. It is shown that the textured surfaces present frictional anisotropy, which depends on the process conditions and modulation parameters. The proposed technique is able to achieve fast generation of various surface textures without additional instrumentation, and the final texture geometry is controllable based on the presented kinematics model.

The circular saw blade body modification by elastic material layer effecting circular saws sound pressure level when idling and cutting

The cutting of wood is proceeded at high feed speed of material and high cutting speed of the circular saw blades. The cicular saw blades teeth rotate in outer ambient and thus are source of noise with unadvisable effects on working environment. The paper presents the results of the measurement of the noise level of three structuraly different circular saw blades. The types of the circular saw blades are: without slots, with six compensating slots in radial direction and with six compensating slots in tangential direction and with compensating slots in conjunction with RAL 9006 paint. The diameters of the circular saw blades were 350 mm. The measurements of the noise level were performed when cutting boards of thickness h = 25 mm (Picea excelsa L.) using the standard equipments. The clamping flanges used had an outside diameter Ø dp = 110 mm. Feed speeds of cut material were vf1 = 12 m/min and vf2 = 17 m/min. The speed of the circular saw shaft for experimental noise level measurements was n1 = 4050 rpm; n2 = 4075 rpm and n3 = 4100 rpm. The different modification of the circular saw blades body when idling only occurred in low differences in equivalent sound pressure levels LAeq ≈ 1 dB. The circular saw blades with compensating slots emit a higher noise level than the corresponding hygiene regulations, but their noise level was of (4 ÷ 6) dB lower than the circular saw blade noise level without slots. The noise level of the circular saw blade with compensating slots in conjunction with RAL 9006 paint was the lowest. Decreasing the value of logarithmic decrement δ of the circular saw blade causes the decreasing the value of the equivalent sound pressure level LAeq of the circular saw at the same design during idling.

Influence of cutting conditions in drilling of CFRP/Al stacked composites

Composite laminates are gorgeous for several applications such as aerospace and aircraft structural components due to their excellent properties. Typically, mechanical drilling has been important machining operation for components made of composite laminates. Nevertheless, laminated composites are considered as hard-to-machine material which results in low drilling efficiency and drilling-induced delamination which is undesirable. This paper reviews the experiments during drilling of CFRP/Al stacked and sandwich composites. The machinability facets of these material stacks has been generally used in aerospace applications, it has been studied based on impact of drill material, drill geometries, and drilling process parameters such as speed and feed. Composite material requires high spindle speed and low feed rate, whereas drilling aluminum requires stability between speedsto feed rate. The review reports essential results and gap in the collected literature for CFRP/Al stacked and sandwich composites. A compromise between several parameters is required during drilling of multi-material stacks. The problems and solutions allied to drilling of multi-material stacks are deliberated and the directions in which the research on drilling of multi-materials may be carried out are suggested in this paper. It is intended to assist readers to acquire a thorough view on mechanical drilling of laminated composite.

Study of dynamic vibration characteristics and suppression of CNC machine tool during operation

The rapid development of aerospace, automobile, national defense and other manufacturing industries has continuously improved the performance requirements of high speed and high positioning accuracy of the CNC machine tool feed system. As the thermal deformation error increases, the system structural rigidity decreases, the vibration increases, and accuracy of machine tool reduces. Existing research mainly focuses on the properties of mechanical and single thermal feed system, and less considers the dynamic performance under the action of thermal-mechanical coupling. For the improvement of feed system performance, it is very beneficiary. This paper takes the high-speed tool of CNC feed system as objective, combined with the actual working conditions to analyze the thermal characteristics, dynamic characteristics and vibration characteristics of the system under the effect of thermal-mechanical coupling. The thermal resistance and convective heat transfer of the key joint surface, the application of moving thermal loads, and the establishment of a simulation model to complete the steady-state temperature field, transient temperature field and thermal-structure coupling analysis. The results show that the maximum temperature rise of the feed system is 21.08 °C, The maximum thermal deformation is 17.264 um. The study found that the parameters such as flow rate and airflow temperature have a significant impact on the cooling effect, so the cooling device was further optimized. This paper proposes a control method for cutting chatter of CNC machine tools based on coupling of characteristics of thermal and mechanical. The thermal characteristic of the feed system and the thermal-mechanical coupling vibration characteristic test provides the maximum temperature error of 3.2 %, verifying the correctness of the theoretical method and analysis model. The highest temperature obtained by the test is 39.7 °C, indicating that the high-speed feed system has a large thermal effect. The relative error of the vibration amplitude of the test and simulation is 12.5 %, which verifies coupling in terms of thermal-mechanical. The accuracy of the vibration analysis method; the experiment depicts that the vibration amplitude increases by 19.7 % under the coupling effect of thermal and mechanical, indicating the effectiveness of dynamic characteristics of the high-speed feed system considering the thermal-mechanical coupling effect.