Internal Cylindrical Grinding Research Articles

Application of TOPSIS Method for Determination of the Best Dressing Parameters in Internal Cylindrical Grinding

Application of TOPSIS Method for Determination of the Best Dressing Parameters in Internal Cylindrical Grinding

Modeling of the material removal rate in internal cylindrical plunge electrochemical grinding

The material removal rate (MRR) in the internal cylindrical plunge electrochemical grinding (ICPECG) is hard to assess because it involves two feed motions: workpiece circumferential rotation and grinding wheel motion in the radial direction. This study attempts to model the MRR and electrochemical overcut in the stable grinding stage of ICPECG by using an equivalent plane electrochemical grinding model with a single feed motion. The differential equation of the interelectrode gap (IEG) in the machining area in the stable grinding stage of ICPECG is derived. Then, based on Faraday's electrolytic law, MRR models of electrochemical anode dissolution (EAD), abrasive mechanical grinding, and electrochemical overcut depth are established and numerically simulated by a variable replacement under different machining parameters. The numerical results indicate that the grinding wheel's radial feed rate most significantly influences the EAD share in the total MRR. In contrast, the power supply voltage mainly controls the electrochemical overcut depth. The proposed model's feasibility and revealed correlations are experimentally verified.

Structural Design of a Special Machine Tool for Internal Cylindrical Ultrasonic-Assisted Electrochemical Grinding.

During the process of internal cylindrical ultrasonic-assisted electrochemical grinding (ICUAECG), both the workpiece and the conductive grinding wheel are rotating, the machining space is closed and narrow, the electrolyte is difficult to spray into the machining area, and the insulation between the workpiece and the machine bed is challenging. According to the machining characteristics of ICUAECG, the structure of a special machine tool was designed to mitigate these problems. In particular, the rotation, electrolyte supply, electric connection, and insulation modes of the workpiece clamping parts were studied, yielding a novel workpiece clamping- and rotating-device design. This structure can fully use the internal space of the hollow spindle of the machine tool, effectively reduce the external moving parts, and achieve the appropriate liquid injection angle of the electrolyte. The ultrasonic vibration system and its installation mechanism, the dressing device of the conductive grinding wheel, and the electric grinding spindle-mounting and -fixing device were analyzed in detail. Then, a special machine tool for ICUAECG was designed, the operability and feasibility of which were verified by experiments involving conductive grinding wheel dressing and ICUAECG.

Experimental study on plunge-cut internal cylindrical electrolysis grinding processing of bearing ring

Experimental study on plunge-cut internal cylindrical electrolysis grinding processing of bearing ring

Experimental study on plunge-cut internal cylindrical electrolysis grinding processing of bearing ring

Experimental study on plunge-cut internal cylindrical electrolysis grinding processing of bearing ring

Studying the Influence of Dressing Parameters on the Surface Roughness when Conducting the External Grinding of SKD11 Steel

This study presents the results of a study on multi-objective optimization of internal cylindrical grinding of hardened SKD11 steel in order to find one objective function which satisfy minimum surface roughness, Ra. By this procedure, an optimum set of dressing parameters such as coarse dressing depth, number of coarse dressing, fine dressing depth, number of fine dressing, non-feeding dressing, and dressing feed speed will be found. Taguchi design methodology is accepted to find the optimum set of dressing parameters which can lead a condition of objective function as above mentioned. ANOVA is conducted based on experimental results to find the significance of each input parameter on the responses. The results reveal that the optimum value of surface roughness is 0.111 μm when using the optimum dressing parameters such as fine dressing depth at level of 2, number of fine dressing at level of 3, number of non-feeding dressing at level of 4, number of coarse dressing at level of 3, coarse dressing depth at level of 2, and dressing feed rate at level of 1.

Simulation Studies on Centrifugal MQL-CCA Method of Applying Coolant during Internal Cylindrical Grinding Process.

This paper describes simulation studies regarding the application of the centrifugal minimum quantity lubrication (MQL) method simultaneously with the delivery of a compressed cooled air (CCA) stream in the internal cylindrical grinding process. The idea of a new hybrid cooling and lubrication method connecting centrifugal (through a grinding wheel) lubrication by MQL with a CCA stream is described. The methodology of computational fluid dynamics (CFD) simulation studies, as well as the results of numerical simulations, are presented in detail. The aim of the simulations was to determine the most favourable geometrical and kinematic parameters of the system in the context of air-oil aerosol and CCA flow, as well as heat exchange. In the simulation, the variables were the grinding arbor geometrical parameters, the angle of CCA supply line outlets, and the grinding wheel and workpiece peripheral speed. As a result of the simulation studies, the most favourable geometrical parameters were designated, determining the orientation of the ends of the two CCA supply line outlets before and after the grinding zone, the number of openings in the drilled-out grinding arbor, and the influence of the grinding speed on the parameters of the coolant flow and temperature of objects in the grinding zone. In addition, the results of simulation tests made it possible to visualise the velocity vectors of the two-phase coolant flow in a complex system of air-oil aerosol delivery centrifugally through an open structure of a very fast rotating porous layer (grinding wheel), with an additional supply of CCA using an external cold air gun (CAG).

Experimental Studies on the Centrifugal MQL-CCA Method of Applying Coolant during the Internal Cylindrical Grinding Process.

This paper presents the results of experimental research concerning the possibility of supporting the cooling function during internal cylindrical grinding using the minimum quantity lubrication (MQL) method by additional delivery of a compressed cooled air (CCL) stream. The article presents a description of a hybrid method of cooling and lubrication of the grinding zone integrating centrifugal (through a grinding wheel) lubrication with the minimum quantity of lubricant and cooling with a compressed cooled air stream generated by a cold air gun (CAG). The methodology and results of experimental studies are also presented in detail, with the aim of determining the influence of the application of the hybrid method of cooling and lubrication of the machining zone on the course and results of the internal cylindrical grinding process of 100Cr6 steel in comparison with other methods of cooling and lubrication, as well as compared with dry grinding. The research results obtained using the described hybrid method of cooling and lubrication of the grinding zone are related to the results obtained under the conditions of centrifugal MQL method, cooling with a stream of CCA, cooling and lubrication with a stream of oil-in-water emulsion delivered using the flood method, and dry grinding. The efficiency of the grinding process is evaluated (based on the average grinding power Pav, grinding wheel volumetric wear Vs, material removal Vw, and grinding ratio G), along with the thermal conditions of the process (based on the analysis of thermograms recorded by infrared thermal imaging method), the textures of machined surfaces (based on microtopography measured by contact profilometry), the state of residual stress in the surface layers of workpieces (determined by X-ray diffraction method), and the state of the grinding wheels’ active surfaces after grinding (based on microtopography measured by laser triangulation and images recorded with a digital measuring microscope). The obtained results of the analyses show that the application of the hybrid method allows for the longest wheel life among the five compared grinding methods, which is about 2.7 times the life of grinding wheels working under the flood cooling and centrifugal MQL methods, and as much as 8 times the life of grinding wheels working under the conditions of CCA only and dry grinding.

New approach for cooling and lubrication in dry machining on the example of internal cylindrical grinding of bearing rings

This paper describes a new method of hybrid cooling and lubrication of the machining zone conducted in dry conditions on the example of internal cylindrical grinding of bearing rings. The idea of the method consists in simultaneous application of a cooling agent in the form of compressed cooled air generated by the cold air gun (CAG) nozzle and a solid antiadhesive and lubricating agent fed to the grinding zone in the form of an impregnate in grinding wheel. Hexagonal boron nitride hBN was used as impregnate. The method of hybrid supply of cooling and lubricating agents configured in such a way allows for dry machining process (without the use of liquid coolants), simultaneously performing the cooling and lubricating functions of liquid coolants in a different, more environmentally friendly form. The article presents the characteristics of a new hybrid method of cooling and lubrication of the machining zone, the results of simulation studies on the flow of compressed cooled air (CCA) and heat exchange in the grinding zone, as well as the results of experimental studies on the process of internal cylindrical grinding of 100Cr6 steel bearing rings using the described method. The conducted simulation tests made it possible to determine the most advantageous conditions of feeding the CCA stream into the grinding zone by means of a two outlet supply line for effective cooling of the grinding zone. The most important result of the experimental research was to demonstrate the possibility of five times longer wheel life in the dry grinding process by using the proposed hybrid method of cooling and lubricating in relation to grinding with a non-impregnated wheel without the application of cooling and lubricating agents. The application of the proposed hybrid method of cooling and lubrication significantly reduced the grinding wheel volumetric wear Vs and made it possible to carry out the machining in stable conditions with more than 4 times higher value of grinding ratio G. Proposed method show its advantages also in relation to workpiece and grinding wheel temperature as well as reduction of grinding wheel cloggings.

Internal Cylindrical Grinding Process of INCONEL® Alloy 600 Using Grinding Wheels with Sol-Gel Alumina and a Synthetic Organosilicon Polymer-Based Impregnate.

The development of modern jet engines would not be possible without dynamically developed nickel–chromium-based superalloys, such as INCONEL® The effective abrasive machining of above materials brings with it many problems and challenges, such as intensive clogging of the grinding wheel active surface (GWAS). This extremely unfavorable effect causes a reduction in the cutting ability of the abrasive tool as well as increase to grinding forces and friction in the whole process. The authors of this work demonstrate that introduction of a synthetic organosilicon polymer-based impregnating substance to the GWAS can significantly improve the effects of carrying out the abrasive process of hard-to-cut materials. Experimental studies were carried out on a set of a silicon-treated small-sized sol–gel alumina 1-35×10×10-SG/F46G10VTO grinding wheels. The set contained abrasive tools after the internal cylindrical grinding process of INCONEL® alloy 600 rings and reference abrasive tools. The condition of the GWAS after the impregnation process was studied, including imaging and measurements of its microgeometry using confocal laser scanning microscopy (CLSM), microanalysis of its elemental distribution using energy dispersive X-ray fluorescence (EDXRF), and the influence of impregnation process on the grinding temperature using infrared thermography (IRT). The obtained results confirmed the correctness of introduction of the impregnating substance into the grinding wheel structure, and it was possible to obtain an abrasive tool with a recommended characteristic. The main favorable features of treated grinding wheel concerning the reduction of adhesion between the GWAS and grinding process products (limitation of the clogging phenomenon) as well as reduction of friction in the grinding process, which has a positive effect on the thermal conditions in the grinding zone.

Geometric Error Modeling and Sensitivity Analysis of CNC Internal Circular Compound Grinding Machine

In order to improve the machining accuracy and efficiency of the hole and sleeve parts, it is necessary to improve the overall grinding accuracy of the CNC (Computer Numerical Control) internal cylindrical compound grinding machine more accurately and efficiently. First of all, it is necessary to clarify the degree of influence of each error parameter on the grinding accuracy, and compensate each error according to the different degree of influence. In this paper, modeling calculation analysis is carried out for a certain type of CNC internal cylindrical compound grinding machine. Firstly, based on the theory of multi-body system dynamics, the topological structure of the CNC internal cylindrical compound grinder is established. According to the topological structure, the position, motion matrix and error matrix of the moving parts of the grinder are written. After data processing, the numerical control internal cylindrical compound grinder is calculated. Use this model to derivate each error parameter to obtain the sensitivity expression of each error parameter. After the actual structure parameters of the grinder are brought into the expression, the sensitivity coefficient of each error parameter can be determined by normalization treatment. The key error parameter with larger sensitivity coefficient is the key error parameter. Finally, several error parameters which have the greatest impact on the overall grinding accuracy of the grinder are obtained. This method provides the basis for the improvement of the grinding accuracy of the subsequent grinder, and creates conditions for the improvement of the machining accuracy of sleeve parts.

Experimental Studies on MoS2-Treated Grinding Wheel Active Surface Condition after High-Efficiency Internal Cylindrical Grinding Process of INCONEL® Alloy 718.

This work demonstrates that molybdenum disulfide can be successfully used as an impregnating substance that is introduced in the abrasive tool structure for improving its cutting properties and favorably affecting the effects of the abrasive process. For the experimental studies, a set of MoS2-treated small-sized grinding wheels with a technical designation 1-35×10×10×109A5X60L10VE0 PI-50 before and after the reciprocating internal cylindrical grinding process of rings made from INCONEL® alloy 718 was prepared. The condition of grinding wheel active surface was analyzed using an advanced observation measurement system based on stylus/optical profilometry, as well as confocal and electron microscopy. The obtained results confirmed the correctness of introduction of the impregnating substance into the grinding wheel structure, and it was possible to obtain an abrasive tool with a given characteristic.

A Study on Coolant Parameters in Internal Grinding of 9CrSi Steel

This paper aims to analysis the effect of coolant parameters on surface roughness in internal cylindrical grinding of annealed 9CrSi steel. The concentration and flow rate of the coolant are investigated in thirteen experiments by central composite design and response surface method. The effect of each parameter and their interaction on the surface roughness are analyzed by their regression model. From that model, optimal parameters are determined to obtain the minimum surface roughness. The measured roughness matches with the predicted roughness from the regression model. This proposed is proven and it can be further applied for optimizing other machining processes.

Quality evaluation of internal cylindrical grinding process with multiple quality characteristics for gear products

Gears are among the most crucial components in the transmission systems of machine tools. Gear manufacturing includes a number of processing procedures. The grinding process is an important procedure involving high precision and fairly small grinding surfaces. For this reason, this study aimed at developing a quality assessment model for the internal cylindrical grinding process of gears. The Six Sigma quality indices (SSQIs) were used to directly assess the quality of the internal cylindrical grinding process due to their ability to directly reflect quality level and process yield. Since the process may include nominal-the-best (NTB), larger-the-better (LTB) and smaller-the-better (STB) quality characteristics, so we used the variable transformation method to normalise the specifications of each quality characteristic for the convenient and effective management and analysis of process performance for multiple quality characteristics. We then constructed a multi-characteristic process quality analysis chart (MPQAC) to simultaneously assess the quality levels of various quality characteristics. Furthermore, the MPQAC can provide references for process improvement. This ensures the quality of internal cylindrical grinding and enhances the quality of gear and machine tool products. Finally, a real-world application and numerical experiments demonstrate the effectiveness and practical applicability of the proposed method.

Multi-objective Optimization of Dressing Parameters of Internal Cylindrical Grinding for 9CrSi Aloy Steel Using Taguchi Method and Grey Relational Analysis

Abstract This study has been done to optimize the dressing parameters in internal cylindrical grinding process for 9CrSi tool steel to minimize surface roughness and maximize material removal rate (MRR) using Taguchi method and Grey Relational Analysis (GRA). This multi-objective optimization is obtained by optimizing five three-level and one six-level dressing parameters in eightteen experiments based on an orthogonal array L18(35×16). The results show that the optimal dressing parameters to obtain the minimal roughness average and maximal MRR are the coarse dressing depth of 0.02 mm, the coarse dressing times of 1 time, the fine dressing depth of 0.005 mm, the fine dressing times of 3 times, the non-feeding dressing of 5 times and the dressing feed rate of 1.4 m/min, respectively. The differences of the roughness average and MRR from the experiments and the predict model are small. Thus, the proposed method has been proven and it can be further applied in other studies.

Experimental studies using minimum quantity cooling (MQC) with molybdenum disulfide and graphite-based microfluids in grinding of Inconel\xae alloy 718

In the paper, the results of experimental studies related with determination of the influence of the supply of a grinding fluid (GF) doped with powdered graphite and MoS2 into the machining zone with the minimum quantity cooling (MQC) method on the course and results of the reciprocating internal cylindrical grinding of rings made from Inconel® alloy 718 have been presented. As a grinding fluid, water aerosols were used. The aerosols delivered the following into the grinding zone: water slurry MoS2 with a concentration of 30 g/dm3, water slurry of graphite with a concentration of 30 g/dm3, 5% water solution of Syntilo RHS oil and pure demineralized water. The obtained results of carried out experiments showed that the most favorable conditions of grinding wheel operation were obtained when MQC-based delivering an aerosol of water slurry made from demineralized water doped with MoS2 and graphite with a minimum flow rate and when delivering an aerosol of 5% water slurry of Syntilo RHS oil. It was proved that doping GF with powdered MoS2 and graphite, with delivery in the form of an aerosol with a minimum flow rate, has a substantial influence on the intensity of clogging grinding wheel active surface (GWAS). Additionally, it has been demonstrated that the solid grease MoS2 and graphite particles reached the area of contact of the GWAS and the machined surface effectively, actively influencing its tribological conditions of the grinding process.

Construction and technical modification of grinding wheels for internal cylindrical grinding using scamper method of creative innovation design

This article describes a case study of an application of the method of creating innovations called SCAMPER for the development of new abrasive tools designed for machining of hard-to-cut materials. The SCAMPER method is used for innovative transformations of existing products, aimed at a modernization of their design, a construction and an extension of functions. This method was used in the procedure of modifying abrasive tools and it permitted a generation of a set of innovative solutions in this field. The methodology made it also possible to logically organize individual creative activities supported by the previously accumulated theoretical and experimental knowledge.

SEM-EDS-based analysis of the amorphous carbon-treated grinding wheel active surface after reciprocal internal cylindrical grinding of Titanium Grade 2\xae alloy

In this article, we described a detailed analysis of the composition of elements remaining on the amorphous carbon-treated grinding wheel active surface (GWAS) after reciprocal internal cylindrical grinding of Titanium Grade 2® alloy. For this purpose, the scanning electron microscope (SEM) combined with energy-dispersive X-ray spectroscope (EDS) techniques were used. The SEM imaging and observation of selected fragments of active surface of 1–35 × 10 × 10-SG/F46G10VTO grinding wheel was mainly carried out by use of two advanced microscopy systems: JSM-5500LV (JEOL Ltd., Tokyo, Japan) and Auriga® (Carl Zeiss Microscopy GmbH, Jena, Germany). During EDS measurements, the Octane plus (EDAX, Inc., Mahwah, NJ, USA)—a high-accuracy silicon drift detector (SSI) was used. Conducted SEM-EDS analysis shows that applied impregnation method ensure the presence of impregnate in a grinding wheel body, also in subsequent work cycles of tool. Observed Ti cloggings on the GWAS appear solely on dulled vertices of active abrasive grains, which demonstrates the limited impact of the impregnate in the zone of direct contact between abrasive grains and machined workpiece surface. However, lack of extensive cloggings of the intergranular spaces indicating an effective removal of long ductile chips of Ti from grinding zone aided by the introduction of an amorphous carbon.

Estimation of the active grains load in different kinematic variations of the internal cylindrical grinding process

This article presents indexes referred to in literature and used when describing the working conditions of abrasive grains in internal cylindrical grinding processes: equivalent chip thickness heq, material removal rate Qw and the proper grinding material removal rate Q′w, as well as the average cross-section of the cut layer AD. From consideration of these indexes, it became apparent that there was a need to develop a new index which would synthetically combine all of the key grinding parameters, as well as the geometric structure of the grinding wheel active surface. A new index was defined, marked as SIQ (synthetic index of single abrasive grain material removal rate), in which the material removal rate Qw was related to the number of active grains on the grinding wheel surface and the converse speed ratio q = vs/vw. The work presents example calculations and charts detailing the changes within the SIQ index values for the following kinematic variations of internal cylindrical grinding processes: traverse grinding, reciprocating grinding, plunge grinding and plunge grinding with grinding wheel oscillations. The work includes an analytical and experimental example of how the SIQ index can be used to determine the grinding parameters within which the grain load remained at a similar level in various kinematic variations of the grinding process. The analyses performed show that application of the proposed index allows for: a comparison of various kinematic variations of internal cylindrical grinding, the selection of machining parameters in instances where the grinding kinematics may need to be altered, the necessity for maintaining the active grains load at the same level, determination of the changes of the active cutting vertexes load during the functioning of select machining parameters, and the comparison of grinding wheels with a variety of active surface geometric structures.

The effect of sulfurization on the grinding wheel cutting ability in the internal cylindrical grinding of nickel superalloys

One possible way of preventing excessive growth of smearings/loads on the grinding wheel active surface is the introduction of compounds such as sulfur, graphite, or wax into the grinding wheel volume which exerts an active influence on adhesion during the process of impregnation. Limiting the formation of smearings/loads on the grinding wheel active surface is of crucial importance to achieve effective grinding of hard-to-cut materials (such as nickel superalloys) which are characterized by considerable ductility and a strong chemical affinity to abrasive grains, among other things. This article presents the results of experimental tests performed on plunge grinding and the influence of sulfur impregnation of grinding wheels on the smearing/load intensity on the grinding wheel active surface during the process of internal cylindrical plunge grinding of openings made from Inconel® alloy 600 and Incoloy® alloy 800HT®. Bearing steel 100Cr6 was included in the tests as a reference material. Grinding wheels were impregnated with a new method of gravitational sulfurization combined with centrifuging. The experiments carried out show that the adhesive properties of sulfur allowed for considerable limitation of smearing/loading of the grinding wheel active surface with machined material. This mainly concerned limiting the formation of the largest and most technologically undesirable smearings/loads of the intergranular spaces. The presence of sulfur in the grinding wheel volume had a minor influence on the intensity of smearings/loads in the microareas of the active abrasive grains’ apexes. The tests also showed an increase of 32%–49% in the value of parameter Sa in the surfaces ground with grinding wheels impregnated with sulfur for all the examined materials.