Papers by Keyword: Creep Feed Grinding

Abstract: Single abrasive-grain cutting is the key research point in grinding process. Because of the narrow space and quick velocity, modeling and simulation method is an approach way to study the single grain cutting. This paper studied the distribution of flow stress and plastic strain, the temperature field near cutting grain. Then experiment was conducted to measure the cutting forces in single grain cutting test. The validation shows good correctness and accuracy of FEA model. Then orthogonal simulation test was carried out to research the influence factors for the grinding forces and temperature distribution. It is found that creep feed grinding has a large grinding forces than high speed grinding in the grain scales. But the maximum temperature value is affected both by depth and speed distinctly.

Abstract: This article studies the performance of ceramic grinding wheel made of micro-crystalline alumina in the creep feed grinding of nickel-based superalloy Inconel 718. The effects of abrasives and specific pore volume on the performance of wheels are experimentally discussed. Grinding force and temperature were measured and analyzed during grinding tests. The surface roughness was used to describe the quality of ground surfaces. The results indicate that the micro-crystalline alumina SG abrasive wheel with large specific volume has good grinding properties when grinding Inconel 718 in comparison of the wheels with PA abrasives or SG abrasives of small specific pore volume.

Abstract: Creep feed grinding can obtain an excellent grinding performance for its creep feed with high depth of cutting. However the large contact length and large feed result in large amount of heat accumulating in working zone and cause burn on workpiece surface. A series of grinding tests are performed to obtain burn variation with grinding parameters using different grinding wheel and workpiece in this paper. Grinding energy is also recorded and used to evaluate the influence of grinding parameter on burn.

Abstract: In this paper, grinding forces of titanium alloy Ti-6Al-4V are measured during creep feed grinding with brazed cubic boron nitride (CBN) wheels. The effects of process parameters on grinding force, force ratio and specific grinding energy are investigated in detail. The grinding force is low and force ratio is about 1.5, and the specific grinding energy of titanium alloys Ti-6Al-4V is about 65J/mm3. Also, CBN wheels brazed with composite filler of Ag-Cu-Ti and 0.5wt.% lanthanum show better grinding performance than the counterpart brazed with Ag-Cu-Ti filler in this investigation.

Abstract: High efficiency and high surface integrity grinding of fused silica lens used in the ultraviolet (UV) laser transmission equipments is highly demanded. It is necessary to decrease the undeformed chip thickness for producing better surface integrity. We conducted creep feed grinding (CFG) and conventional shallow cut grinding (SCG) experiments of fused silica with a resin bond diamond wheel. Experiment results shows that owing to thinner undeformed chip thickness, the normal grinding force, radial wheel wear and P-V value of surface roughness of CFG are smaller than those of SCG at the same MRR. At the same table speed, surface roughness decreased with the increase of MRR in both CFG and SCG as a result of decreased undeformed chip thickness which is attributed to the elasticity of resin bond.

Abstract: Force and specific energy are important factors in all abrasive machining operations especially in creep-feed grinding of hard materials. They have a high influence on the wheel wear, grinding accuracy, grinding temperature and surface integrity. This paper investigates the effect of grinding technological parameters on grinding force and specific energy in up-cut creep-feed grinding of cemented tungsten carbide with 20% cobalt using a resin-bonded nickel-coated diamond wheel. It was observed that increase of feed rate resulted in grinding force increase and specific energy decrease. Increased wheel-peripheral speed resulted in minor decrease of grinding force and specific energy increase.

Abstract: Recent advances in materials science have necessitated the development and understanding of manufacturing processes for safe and repeatable utilization. Grinding is shown to be a promising material removal process especially for brittle and hard to cut materials such as superalloys. Grinding has always been associated with analysis and modeling complications regarding its nature which has limited its extension and reliability of use. The first step in analysis of grinding is considering the action of a single abrasive grit on workpiece surface. In this work the action of a single CBN abrasive grit in creep-feed grinding process of Inconel 718 superalloy is modeled and analyzed using a 3D FEM software, DEFORM. Thermal and mechanical characteristics of the mutual interaction between grit and workpiece surface, and different chip formation phases are defined which can further be used to analyze the whole process.

Abstract: Generally in the grinding of modern aviation materials such as nickel-based superalloys, problems frequently occur in terms of burr formation, profile loss of the wheel, high heat generation in the contact zone, high grinding forces as well as low process reliability. A recent and promising method to overcome these technological constraints is the use of ultrasonic assistance, where high-frequency and low amplitude vibrations are superimposed on the movement of the workpiece. This paper presents the design of an ultrasonically vibrated block sonotrode and the experimental investigation of ultrasonically assisted profile grinding of Inconel 718. The profile wear, radial wear of the wheel, grinding forces and surface roughness by ultrasonic-assisted and conventional profile grinding were measured and compared. The obtained results show that the application of ultrasonic vibration can decrease the radial wear of the wheel, profile wear, grinding forces and surface roughness considerably.

Abstract: Creep-Feed Grinding(CFG) is one of the none-traditional machining in which form grinding to full depth is performed in limited number of passes. One of the most significant criteria which is taken into account to display valid machining parameters, is surface integrity. Surface integrity in CFG process is influenced by four main factors including surface roughness, superficial micro-crack, burning and changes in micro-hardness. According to prior investigations in CFG process, depth of cut plays an important role in surface integrity. In this study, the influence of cutting depth on workpiece surface integrity of cast nickel-based superalloy with alummina wheels, was investigated. During this study, a sample part was machined with variable depth of cut while the other parameters were Constant. After machining, surface roughness of each specimen was measured and in order to investigate existence and dimensional situation of surface micro-cracks, Chemical Etch + FPI and Thermal shock + FPI were performed. For determining micro-structural changes in ground specimens as a clarifier criteria in measuring the level of residual stress, a set of recrystallization processes were carried out on them and average grain size were measured. The results show, however, changing in depth of cut hasn't influenced on micro-cracks, quality of surface roughness has descended in terms of increasing the cutting depth.

Abstract: Technology of NC-contour evolution ultrasonic assisted creep feed grinding (NC-CEUACFG) blade surface was put forward to solve the difficult problem of machining ceramic blade surface. The static load on the grinding wheel and the influence of the rigidity of the grinding wheel on the surface precision were studied combined with the movement analysis between the blade and grinding wheel in the process of NC-CEUACFG ceramic blade surface, and the physical model of static load may explain the decrease of grinding force and increase of the relative rigidity of the grinding wheel in NC-CEUACFG in theory. The primary experiment of NC-CEUACFG blade surface was carried out according to the experimental results of previous optimized process parameters, and the integral impeller was machined directly in the blank material of Al2O3 ceramic, which indicated the application prospect of such technology.