Wheel Feed Research Articles

Experimental analysis of chemical removal effect in RISA grinding of optical glass

In the large-aperture lens manufacturing, not only high surface quality but also high productivity is required. From this perspective, Reaction-Induced-Slurry-Assisted grinding (RISA grinding), in which cerium oxide slurry is supplied instead of using general grinding fluid, has been developed to achieve high surface quality at high removal rate. However, the surface profile error becomes large due to chemical removal effect of the cerium oxide slurry. Therefore, the purpose of this study is to experimentally investigate the influence of the chemical removal effect on the surface profile error using AE signals and servo current signals in RISA grinding. First, relation between dwell time and removal depth is analyzed by conducting a basic grinding test without the workpiece rotation. The result shows that the actual removal depth increases with increase of dwell time despite applying the constant depth of cut. Then, zero-cut RISA grinding test is conducted. It is found that the removal process proceeds even though zero-cut grinding, and its removal rate varies according to the wheel feed rate. Furthermore, the amount of cerium oxide abrasives adhered to the grinding wheel can be estimated from the AE signals and servo current signals.

Toward an Improved Understanding for Design of Material Extrusion Additive Manufacturing Process‐Based 3D Printers—a Computational Study

AbstractUnderstanding and improving 3D printing process models are very important for designing building defect‐free 3D printers. Most studies have failed to present detailed process design and modeling of material extrusion (MatEx)‐based additive manufacturing (AM) in a systematic approach that considers all process parameters such as nozzle diameter, nozzle angle, and velocity. It is studied that the accuracy and consistency of a MatEx 3D fabricated product depend on the pressure drop across various nozzle zones. This paper identifies the constraints affecting the performance of the MatEx AM process and presents mathematical modeling related to various process parameters. Also, the paper shows expressions for pinch wheel feed mechanism, liquefier, and nozzle geometry of the MatEx process in terms of independent variables, such as liquefier temperature, nozzle geometry, and feed rate. This will be helpful in computing the precise design parameters of MatEx‐based 3D printers. The complex mathematical expressions developed are pivotal for the effective regulation of the 3D printing process. It not only provides new and better designs for MatEx machines with precise operation and better resolution but also opens the scope for further scientific development to expand the capability of proposed approach for both specific applications and the field.

Diagnosis of two-axis cylindrical grinder machining error

This paper attempts to develop a machining error diagnosis method for classifying the error sources on the external/internal contour surfaces which are fabricated using a two-axis cylindrical grinding machine. A derivation of the contour profile to grinding wheel motion trajectory and also the grinding wheel motion trajectory to the contour profile equations has been performed. Due to the contours having a sinusoidal polynomial polar curve instead of a rose curve, the grinding wheel motion trajectory equation is then used to generate the NC code for the machining. The grinding wheel motion trajectory equation is needed for the synthesis of the profile error caused by the motion error as well as the variation of the grinding wheel diameter. The two-axis motion equation is obtained by transforming the non-circular contour equation through the coordinates of the grinding wheel and workpiece. The influence of different machining parameters such as grinding wheel outer diameter error, grinding wheel feed rate, and workpiece rotation speed on the external/internal contour profile is being studied and analyzed. The diagnosis method is based on the least square method to assemble the components of the profile error due to each individual error sources. The actual machining with probe system is used to verify the diagnosis result.

Experimental study on the macerals enrichment of low-rank coal by rotary triboelectric separator

The improvement of vitrinite content in low-rank coal can enhance liquefaction efficiency. In this work, an innovative rotary triboelectric separator (RTS) was used to enrich the macerals of low-rank coal. The effects of friction wheel speed (A), separation voltage (B), and feed rate (C) of RTS on the macerals enrichment were investigated, and the interactions of the three factors were explored via the response surface method. By the established model, all the three factors have significant effects on the vitrinite recovery R v, and the interaction between AC is stronger than AB and BC. Taking the maximum value of R v as the optimization target, the optimal prediction index was obtained and validated based on laboratory experiments. Under the optimum operating conditions, a maximum R v value of 74.48% was achieved at a friction wheel speed of 3220.14 rpm, a separation voltage of 30.18 kV, and a feed rate of 1.44 g/s. The average vitrinite content and R v of the verification experiments were 65.45% and 74.71%, respectively.

A study on tangential ultrasonic-assisted mirror grinding of zirconia ceramic curved surfaces

Zirconia ceramics have been used in the field of smartphone manufacturing, especially for the phone shells. To improve the machining efficiency and simultaneously obtain a mirror-surface quality on the curved surface made by zirconia ceramics, the tangential ultrasonic-assisted grinding (TUAG) was proposed, in which the ultrasonic vibrations of the grinding wheel are always in the direction tangential to the work surface at the grinding point. To reveal the fundamental grinding characteristics of the TUAG on the zirconia ceramic curved surface, the processing principle and according experimental setups were given out at first. The effects of the proposed method on the surface morphology and surface roughness were investigated experimentally and analyzed numerically under different process parameters for plane workpieces. Finally, a curved surface was successfully processed by the novel method with the optimized experimental conditions. The obtained results demonstrated that (1) typical sinusoidal cutting traces appeared on the work surface, which implied that the surface morphology was affected significantly by the ultrasonic vibrations; (2) the surface roughness was distinctly affected by the amplitude of the grinding wheel, and a higher efficiency was attained on the surface quality enhancement when the larger amplitude was applied, e.g., Ra was reduced by 58.3% when an amplitude of Ap–p = 4.66 μm was imposed; and (3) the Ra value in the direction vertical to the wheel feed direction on the curved surface decreased to 39.5 nm, implying that a mirror curved surface can be obtained by TUAG with the appropriate process conditions.

Wear of a Diamond Wheel during Grinding of Ceramic Balls Made of Silicon Carbide

The results of an experimental study of the effect of the mode of processing on the wear of the diamond wheel surface and on the accuracy of batch processing during diamond grinding of ceramic balls made of silicon carbide are discussed. The grinding pattern and the frequency of wheel strokes have a statistically significant effect on the maintaining of the original flat shape of the wheel, while the discrete feeding of the wheel has no direct effect on its uneven wear. The condition for minimizing the difference in the diameter of the balls within a batch and maintaining the original flat shape of the wheel will be the choice of grinding pattern with the trajectory of the balls tangent from the inside to the outer edge of the wheel, as well as minimizing the discrete feed of the wheel in the investigated range when grinding and a simultaneous increase in the wheel feed frequency to the maximum. However, the variance of the ball diameter within a batch under these conditions does not reach the minimum possible value.

Numerical investigation on roll forming of straight bevel gear

Gear is an important power transmission part, which has been widely used in aviation, aerospace, vehicles, instruments, mining machinery, and other industries. The gear teeth are formed with two methods of chip removal processing and precision plastic forming. The plastic forming method overcomes the defects of chip forming; the internal metal flow line is continuous, the material utilization ratio is high, and the production efficiency is high. In order to avoid the defects of rabbit ear in gear roll forming, the forming process of rolling bevel gear is studied in this paper. Studies have shown below. In the process of forming the bevel gear, the defects of the rabbit ears will be generated, and finally, the defects of the folding are formed in the forging. The defects of the rabbit ears must be eliminated during the forming process. When the friction shear factor is 0.1, 0.3, 0.5, 0.7, and 1.0, the maximum increment of rabbit ear is about 0.51 mm. The left profile first forms the top of the tooth, and the tooth top of the left tooth profile forms the left rabbit ear under the extrusion of the convex tool. The right-hand contour of the tooth blank is finally formed, and the rabbit ear of the right tooth profile is formed by the bending extrusion of the convex tool. In the multi-pass roll forming method, the occurrence of rabbit ear defects in roll forming process is effectively suppressed when the big end tooth height of bevel gear is 3.2 mm, 6.5 mm, 9.8 mm, and 13.1 mm and rolling wheel feed is 1.9 mm, 3.5 mm, 5.2 mm, and 6.9 mm, respectively.

Spinning Process Test and Optical Topography Measurement Technology for the Shell with Longitudinal and Latitudinal Inner Ribs

The paper studies the complicated problem in the spinning process of the shell with longitudinal and latitudinal inner ribs. The finite element software ABAQUS is used to establish the finite element model of the cylindrical shell with the longitudinal and latitudinal inner ribs. The numerical simulation of the spinning process is carried out. The stress distribution and strain distribution of the inner and outer surfaces during the spin-forming process are determined, and the orthogonal test method is used to determine the optimization process test parameters. The influence of the main process parameters on the wall thickness difference of the inner rib shell is obtained by the range analysis: wall thickness reduction rate > rotary wheel feed speed > rotor working angle (arranging according to their influences). And then the corresponding process parameters recommended by the spinning test are given. The measurement problem of inner ribs is solved by building of the robot shape measurement system which helps detect the three-dimensional shape of the inner ribs, and the precision of the spun sample was detected by the point cloud deviation comparison.

The Influence of Machining Conditions on Performance of Diamond Grinding of Silicon Carbide Ceramic Balls

The paper presents some results of an experimental investigation of the influence of machining conditions on the process of diamond grinding of silicon carbide ceramic balls. The process performance parameters are the rate of the ball diameter reduction, the rate of change (decreasing/increasing) of the deviation from spherical form, and the rate of change of the variation of ball lot diameter. To separate the portion due to solely the influence of the machining conditions, the authors have applied a method of graphical approximation of the time behavior of mean value of ball accuracy characteristics per batch. It has been found out that the separated portions can change upwards or downwards depending on the values of the machining conditions, namely: diamond wheel infeed, wheel feed rate, and ball-holder table rotational speed. The full factorial experiments of type 23 have revealed the most effective (for correcting the ball shape) combination of the factors studied, which is different for each of the three ranges of such deviation: above 300 μm, within 150–300 μm, and below 150 μm.

Research on influence of spinning process parameters based on simulation and experiment

In this paper, we focus on the need for the process of spinning manufacturing, the spinning manufacturing simulation of INCONEL718 cylinder part was finished, the scheme consists of two-pass and three wheels spinning, three wheels offset. The FEM (finite element analysis) was used to finish the spinning manufacturing simulation, the stress-strain cloud picture was attained, it takes the wall thickness difference as analysis object, the influence law of spinning wheel feed rate and spinning wheel working angle was analyzed, the spinning manufacturing experiment was done based on the parameters attained by simulation, experimental result coincides with the simulation result. The experimental result shows that the simulation methods and parameters are beneficial to the actual spinning manufacturing.

Experimental Study on Grinding Force of Zirconia Ceramics in Dry/Wet Grinding Environment

The impacts of different linear speed of grinding wheel, grinding depth and workpiece feed speed with or without grinding fluid on grinding force were studied by plane grinding machining of zirconia ceramics. The impacts of different machining environment and grinding parameter on normal and tangential grinding forceswere studied by testing the grinding force during grinding with a force measuring device. The studies showed that the normal and tangential grinding forces decrease with the increase of the linear speed of grinding wheel and increase with the improvement of grinding depth and workpiece feed speed. The grinding depth has the greatest impacts on the normal and tangential grinding forces in dry grinding environment; while in wet grinding environment, the grinding depth exerts the greatest impacts on the normal grinding force and the linear speed of grinding wheel imposes the greatest impacts on the tangential grinding force. In addition, it was found that the normal grinding force in dry grinding is minor than that in wet grinding, that the tangential grinding force in dry grinding is greater than that in wet grinding, and that the grinding force ratio in dry grinding is lower than that in wet grinding.

Experimental study of surface performance of monocrystalline 6H-SiC substrates in plane grinding with a metal-bonded diamond wheel

Monocrystalline SiC has long been recognised as an ideal third-generation semiconductor material for application in situations where there is high frequency, high power and high voltage. Because of the hardness, stiffness and strength of monocrystalline SiC, these materials are extremely difficult to machine in order to produce the extremely flat, smooth and damage-free surfaces required in many industrial applications. This paper presents the results of plane grinding experiments which were carried out using a metal-bonded diamond wheel. The process parameters of these have demonstrated a significant influence on surface roughness. Surface quality improved and roughness decreased as the wheel feed rate decreased. On the substrate surfaces, the particle trajectory density increased closer to the centre, producing better surface quality. At large feed rates, the material removed is mainly brittle fracture, and the plough scratch widths and gully depths on the ground surface are greater. At small feed rates, plastic removal predominates, becoming more significant closer to the centre and giving a smoother surface. Median and transverse cracks occur in the subsurface damaged layer, and the crack depths are consistent with the surface roughness Rz and gully morphology. Then, the critical grit depth of cut and the maximum undeformed substrate thickness values under different grinding conditions were calculated in order to analyse the characteristics of the subsurface damage and the material removal mechanism. Finally, an optimised process was achieved using orthogonal experiments, with processing parameters for rough, half-fine and fine grinding. This process gives flat substrates with surface roughness Ra 0.012 μm, SSD < 4 μm and TTV < 3 μm, which achieves the same level of precision as lapping.

Sphere forming mechanisms in vibration-assisted ball centreless grinding

This paper aims to clarify the sphere forming mechanisms in vibration-assisted ball centreless grinding, a new technique for effectively processing balls using ultrasonic vibrations. Based on a comprehensive analysis of the ball rotation motion, geometrical arrangement and stiffness of the whole grinding system, a reliable mechanics model was successfully developed for predicting the sphere forming process. Relevant experiments conducted showed that the model had captured the mechanics and the major sphere forming mechanisms in ball centreless grinding. It was found that the ball whole surface can be well ground with a high accuracy, while efficiency is much enhanced compared with that in the traditional methods. The ball rotational speed which is controlled by the ultrasonic regulator has a great impact on final sphericity, and the speed controlled by the ultrasonic shoe dominates the whole processing time. To achieve a stable and high precision grinding, the ball needs to rotate rhythmically, and the wheel feed per step and the ball location angle should be controlled in a critical range.

RETRACTED: A pure thermal model to evaluate heat-affected zone when milling E-glass fiber-reinforced polyester composites

This paper aims at investigating the resistance-to-vitrification of glass fiber-reinforced plastics when milling. A three-dimensional thermal model using volumetric heat source with Gaussian distributed cylindrical flux was developed as DFLUX subroutine and implemented into Abaqus/Standard code. The wheel feed was simulated by the source motion at 250 mm min−1 with spindle speeds of 11,460, 15,280, and 19,100 rpm. Milling tests using abrasive wheel with 10 mm in diameter were conducted on the composite specimens of dimensions 100 × 25 × 4 mm3 with fibers oriented both parallel and perpendicular to the milling direction. Four equidistant thermocouples were embedded within the medium plane of the specimen in order to measure the temperature histories. Each series of tests was repeated four times under identical conditions. Predictions confronted to measurements demonstrated the validity of the proposed model. Cutting perpendicular to fibers was found favoring in-depth heat dissipation. However, the fibers a...

Experimental Study of Machining Parameters in Cylindrical Components using Abrasive based Finishing Process

Resent advancement in manufacturing sectors to make extremely precise products using diverse technical aspects of machining, an unconventional (non-traditional) machining process. Nano-polishing technique is an ultra-fine surface finishing process applied for advanced engineering applications like bearing, biometric piston, piston rings and medical components. Present work is mainly concentrated on micro machining to nano level machining with the aid of abrasive particles SiC and CIPs particles and silicone oil. In this experimental study, magneto rheological cylindrical finishing (MRCF) process is developed for finishing stainless steel (AISI 304 L) of 200mm diameter and length is 175mm. The permeability test was conducted to find permeability number based on size of abrasives in the MR fluid. Before we estimated permeability number for fine metal removal of harden material, also considered magnetic flux density, forces acting on the workpiece, carrier wheel speed, feed rate, and working gap. Tests were carried out based on central composite design matrix to estimate the effects of machining parameters such as working gap, wheel speed, carrier wheel speed and feed rate.

Performance Analysis of Cylindrical Grinding Process Parameters Using Grey Relational Technique&lt;sup&gt;&lt;/sup&gt;

The present research work involves investigating the cylindrical grinding process parameters of Al/SiC metal matrix composites during machining. The effect of grinding process parameters on grinding force, surface roughness and grinding temperature were investigated experimentally using L27 orthogonal array. Grinding process was carried out using different combination of wheel velocity, workpiece velocity, feed rate and depth of cut. The significant grinding process parameters have been determined by using ANOVA. The grey grades identify the optimum level grinding process parameters. From the grey relational grade, low wheel velocity, medium workpiece velocity, medium feed rate and medium depth of cut gives the best results.

머시닝센터를 이용한 내면 스러스트 연삭가공에 관한 연구

In this paper, the grinding characteristics of internal thrust grinding were studied with vitreous CBN wheels using a machining center. Grinding experiments were performed according to grinding conditions, such as wheel feed speed and depth of cut, workpiece speed, and rate of grinding width. Additionally, the grinding force and grinding ratio were investigated though these experiments. Based on the experimental results, the grinding characteristics of internal thrust grinding were discussed.

Simulation of powder flow in a lab-scale tablet press feed frame: Effects of design and operating parameters on measures of tablet quality

The feed frame of a pharmaceutical tablet press is an important process component critical in defining both the total tablet mass and the amount of the active pharmaceutical ingredient (API) within the tablets. In addition to these quantities, the mechanical agitation of the feeder can cause attrition or over-lubrication of the powder blend or granulation flowing through the device. In order to better understand these effects, the discrete element method is used to model powder flow in a single paddle wheel feed frame of a laboratory-scale tablet press with varying particle, process, and equipment parameters. Results show that widely varying particle flow patterns and residence time distributions are achieved for varying paddle wheel shape, rotation direction, and rotation speed. Faster paddle wheel speeds generally lead to more uniform tablet masses whereas slower paddle wheel speeds perform less work on the particles (a surrogate for attrition) and move the particles a smaller distance (a surrogate for the extent of lubrication) in the feed frame before they enter a die and are compressed into a tablet. Finally, the effects of paddle wheel design and powder cohesion are also described.

On the Profile and Microstructure Variations of Grinding-Induced Hardening Layer in A Cylindrical Workpiece

Grinding-hardening is a thermo-mechanical process capable of simultaneous material removal and surface enhancement. However, there are difficulties in dealing with cylindrical workpieces, because of the complex 3D-helical movement of the grinding-induced heat source. This paper investigates the effects of some key grinding parameters on the profile and microstructure variations of the hardened layer generated by a traverse cylindrical grinding, both experimentally and numerically. It was found that the ratio of the longitudinal wheel feed to the rotational speed of the workpieceRis most influential on the hardened layer profile. A largerRresults in a thicker hardened layer but a more pronounced discontinuity of two adjacent hardening zones. Although a smallerRyields a relatively thinner hardened layer, the non-uniformity could be minimised by the overlapping of the grinding heating. The microstructure of the hardened layer can be altered by the tempering in subsequent grinding heating. A thermal analysis with the aid of the finite element method in conjunction with an experimental microstructural examination showed that the temperature distribution in the tempered region would lead to a variation of the precipitated carbide, and that a higher tempering temperature could result in a higher degree of the carbide precipitation and a more significant reduction of hardness.

Optimization Method of Workpiece Rotation Shaft Speed of CNC Camshaft Grinding Machine

Based on the constant removal rate method, the mathematical model of the cam grinding is built. Through analyzing the cam's grinding model, the constraints of cam's driver, some system's parameters are obtained, such as the slow-down ratio of workpiece, and the maximal speed, the maximal acceleration and the maximal differential acceleration of the wheel's horizontal feed. A control method of the grinding wheel's feed speed is proposed. The forward and reverse interpolation point can be dynamic solved to meet the maximum wheel's feed speed, and the optimal interpolation is achieved. Finally, the algorithm is simulated by Matlab, and it is applied to YTMK-CNC8336-16, which is a CNC camshaft grinding machine. The experimental results indicate that the camshaft lifting error is less than 0.015 mm, the surface roughness is less than 0.25 μm, and the grinding efficiency is increased by 30%.