Grinding Head Research Articles

Grinding performance evaluation of a novel 3D-printed double-layer diamond grinding head in cemented carbide grinding

Grinding performance evaluation of a novel 3D-printed double-layer diamond grinding head in cemented carbide grinding

Research on the effect of grinding force on the axial ultrasonic vibration-assisted grinding of Ti-6Al-4V with multi-grain conical grinding head

A multi-grain conical grinding head capable of performing both peripheral and end-face grinding was created in Abaqus to simulate conventional grinding (CG) and axial ultrasonic-assisted vibration grinding (AUVAG) on Ti-6Al-4V alloy. A comparative analysis was conducted to examine the effects of key grinding parameters on the fluctuation amplitude and mean value of grinding forces in CG and AUVAG. The mechanism of ultrasonic vibration’s influence on grinding forces was analyzed, and a theoretical model for normal and tangential grinding forces in peripheral grinding of Ti-6Al-4V was established. Additionally, the surface morphology of CG and AUVAG was analyzed. The study found that the fluctuation amplitude of grinding forces in both AUVAG and CG increases with the axial grinding depth, feed rate, ultrasonic amplitude, and ultrasonic frequency, while it decreases with increasing spindle speed. However, the fluctuation amplitude in AUVAG is greater than that in CG. The average grinding forces in both CG and AUVAG increase with the grinding depth and feed rate, and decrease with the spindle speed. Compared to CG, the mean F x ([Formula: see text]) and F y ([Formula: see text]) are lower in AUVAG, while the mean F z ([Formula: see text]) is higher. Under different axial grinding depths, the maximum reduction in [Formula: see text] and [Formula: see text] for AUVAG is 4.70% and 5.18%, respectively, while the maximum increase in [Formula: see text] is 77.48%. At different feed rates, the maximum reduction in [Formula: see text] and [Formula: see text] for AUVAG is 3.02% and 21.01%, respectively, while the maximum increase in [Formula: see text] is 81.67%. Under different spindle speeds, the maximum reduction in [Formula: see text] and [Formula: see text] is 7.20% and 17.82%, respectively, and the maximum increase in [Formula: see text] is 281%. As the ultrasonic amplitude and frequency increase, [Formula: see text] significantly rises, but the effect on [Formula: see text] and [Formula: see text] is weak. AUVAG improves the surface quality of the specimen.

Vibration modal analysis of adaptive grinding and polishing tools

Abstract Adaptive grinding and polishing tools have a compact structure, fast response, and stable performance, and they can improve the efficiency of polishing and grinding large welded parts. The vibration frequency of the AGP600 adaptive grinding and polishing tool is abnormal after switching from the blade grinding head to the nylon grinding head, and the vibration is noticeable when the rotational speed is more significant than 4, 000 r/min, which seriously affects the quality of grinding. To analyze the cause of its vibration, this paper adopts HyperWorks to analyze the modal frequency of AGP600, carries out the vibration modal test, and analyses the reasons for the different vibration harmonic frequencies of AGP600. Finally, improvement measures for AGP600 are proposed, through which the vibration of AGP600 grinding tools can be reduced.

Piezoelectric Ultrasonic Local Resonant Ultra-Precision Grinding for Hard-Brittle Materials.

Hard-brittle materials are widely used in the optics, electronics, and aviation industries, but their high hardness and brittleness make it challenging for traditional processing methods to achieve high efficiency and superior surface quality. This study aims to investigate the application of ultrasonic local resonant grinding to sapphire to improve the efficiency and meet the requirements for the optical window in the surface roughness of the material. The resonant frequency of a piezoelectric ultrasonic vibration system and the vibration amplitude of a grinding head's working face were simulated and tested, respectively. The results of ultrasonic grinding experiments showed that the local resonant system reduced the surface roughness parameter (Ra) of sapphire to 14 nm and improved its surface flatness to 44.2 nm, thus meeting the requirements for the ultra-precision grinding of sapphire. Compared with a conventional resonant system, the surface roughness of the sapphire ground with the local resonant system was reduced by 90.79%, its surface flatness was improved by 81.58%, and the material removal rate was increased by 31.35%. These experimental results showed that ultrasonic local resonant grinding has better effects than those of conventional ultrasonic grinding in improving surface quality and increasing the material removal rate.

Prediction model of grinding roughness for worm with complicated space tooth surface

Optimum grinding parameters are crucial for achieving high-quality grinding of helical tooth surfaces for worm drives. The complex coupling motion relationship and formation mechanism between the worm blank and the grinding head make it difficult to predict the effect of grinding parameters on tooth surface roughness. Therefore, we developed a prediction model for the worm tooth surface roughness under conjugate grinding and applied it to the Roller Enveloping Worm Reducer (REWR). The forming process of the theoretical worm tooth surface during the grinding process was modeled by using the conjugate meshing principle. Considering the plowing and cutting effects of grinding particles on the tooth surface at different design parameters, feed speeds, and rotational speeds of the grinding head, the roughness prediction equation was established based on the theory of the maximum depth of valley bottom. Through the coupling analysis of the theoretical tooth surface model and the roughness prediction model, the prediction of the worm tooth surface roughness is realized. Based on the validated model, the influences of grinding parameters on the worm tooth surface roughness of REWR were quantitatively discussed. This study is of great significance for optimizing process parameters in the grinding of complex spatial surface transmissions.

Bidirectional long-short term memory predictor for material removal rate in computer-controlled optical surfacing

In Computer-Controlled Optical Surfacing technology, the precision of the removal function directly affects the accuracy of computer-aided processing software predictions, which in turn influences subsequent polishing machine processing. A key parameter for constructing the removal function is the material removal rate, which is often challenging to obtain accurately. Currently, the Preston equation is widely used to describe the principles of material removal. However, as a linear equation that omits many factors, it struggles to accurately model the removal function in complex machining scenarios. Therefore, this paper proposes a hybrid neural network model combining Convolutional Neural Networks and Bidirectional Long Short-Term Memory to predict the material removal rate. The model's parameters are optimized using an improved Grey Wolf Optimization algorithm, ultimately establishing a removal function closely consistent with an actual removal function. We first tested our method on the PHM2016 Data Challenge dataset, achieving a mean squared error of 6.19 and an R2 of 0.9949, outperforming other mainstream neural network prediction models developed in recent years. Additionally, we further validated the performance of the neural network using a small grinding head polishing dataset, achieving MSE and R2 values of 1.9035 and 0.99902, respectively. Finally, we applied this method to construct the removal function on an actual small grinding head production line. Compared to the traditional Preston equation-based removal function, the predicted residual surface's PV and RMS errors were reduced from 28.24 % to 35.58 %–4.563 % and 4.86 %, respectively. These validation results demonstrate that the proposed method not only facilitates easier acquisition of the removal function model but also significantly enhances the accuracy of computer-aided processing software predictions, thereby better guiding ultra-precision machining processes.

Effects of different tooth grinding procedures on the occurrence of tooth injuries, skin lesions, performance and behaviour of suckling piglets

BackgroundImmediately after birth, newborn piglets fight to establish a teat order. During this process, lesions appear on the piglets’ faces and on the sows’ teats, which is why tooth resection is carried out on many farms in Germany even though it is known that this procedure is frequently resulting in pulp openings. The opening of a pulp cave is suspected to cause painful tooth alterations and may be an entrance for infectious agents. The purpose of this study was to analyse the effect of tooth resection on skin lesions, development of bodyweight and behaviour in suckling piglets. Four days prepartum, 110 sows in farrow-to-finish production were assigned to one of three treatments. Litters had their teeth left intact (control group, CG), ground with a tea-cup roller head (Tea-cup head grinder group, TCG, Wilofa Diamant, D-56,133 Fachbach, Germany) or ground with a diamond rolling head (rolling head grinder group, RG, IBS/E Company Proxxon GmbH, 54,343 Föhren, Germany). The number of pulp openings in the RG and TCG was examined using a random sample. Piglet body weight and skin lesion scores were recorded within the first 24 h after birth and during each week of the suckling period. Each sow’s udder was examined before farrowing, in the second week of lactation and at weaning. The behaviour of the litters from nine sows was video-recorded throughout the suckling period. The aim of this study was to investigate the effects of tooth grinding by a tea-cup head (compared to grinding by a diamond roller head and no grinding [control group]) on the behaviour and average daily gain of piglets as well as on skin lesions on sow udder.ResultsThe number of dental injuries was significantly greater in the RG than in the TCG (p < 0.01). Head lesions on piglets were significantly more common in the CG than in the RG (p = 0. 02). Compared to CG piglets, TCG piglets had a significantly greater weight at the end of the suckling period (p = 0.02). No significant difference between treatments was found in the sows’ udder (parenchyma, skin, or teat) or in the behaviour of the litters.ConclusionAs tooth grinding is frequently inducing pulp openings, the necessity of the procedure should be carefully and critically scrutinised. In case tooth resection seems inevitable until the underlying management problems have been solved, the Tea-cup grinding head should be used due to significantly fewer pulp openings.

Effect of the Axial Profile of a Ceramic Grinding Wheel on Selected Roughness Parameters of Shaped Surfaces Obtained in the Grinding Process with a Dual-Tool Grinding Head.

The use of CNC equipment that integrates several machining operations eliminates downtime due to changes in setup and clamping of workpieces in more than one machining device. A review of CNC equipment and tools known from the literature and from manufacturers' offerings indicates that new technical solutions are being developed to integrate two or more technological operations. However, these examples have numerous limitations and are mostly not suitable for machining surfaces with complex shapes. An example of such solutions is the use of a dual-tool grinding head, which integrates the process of rough grinding with a ceramic grinding wheel and finish grinding with a flexible grinding wheel. Unfortunately, it has the disadvantage of being limited by the angular shape of the ceramic grinding wheel, making it unable to adapt to the complex geometries of the shaped surfaces being ground. The need to overcome this limitation became the motivation for the research work described in this article. By means of experimental research, it was verified what effect the radial outline on the periphery of a ceramic grinding wheel realized by rough grinding would have on the surface roughness parameters obtained in the process of grinding shaped surfaces. For this purpose, grinding processes using a ceramic wheel with a conical and radial outline were compared. The result of the study was a summary of the surface roughness parameters Sa, St, Sq, Spk, Str, and Sds obtained after two-stage machining (rough and finish grinding). The obtained analysis results showed that changing the axial outline of the ceramic grinding wheel makes it possible to significantly expand the range of applications of the dual-tool head without negatively affecting the quality of the machined surface. Thus, such an improvement will make it possible to increase the applicability of the head by grinding shaped surfaces with a radial profile of curvature.

Effects of Two Different Methods of Teeth Grinding on Dental Injuries, Skin Lesions, Growth and Behaviour of Suckling Piglets Compared to a Non-Treated Control Group.

Teeth grinding in suckling piglets is performed on many farms to protect the piglets' littermates and the sow's udder from injuries caused by the piglets' canines and third incisors. In this study, the effects of two teeth-grinding methods on the piglets' dental health and welfare were investigated. The piglets of a litter were evenly assigned to a treatment: one-third of littermates were ground with a roller grinding head (RG), one-third with a teacup grinding head (TCG), and one-third were not ground at all (CG). A random sample of 100 animals each from the RG and TCG treatment was examined for tooth injuries, i.e., dental pulp openings. Additionally, behavioural analysis was performed (n = 650 piglets), and skin lesions, growth and mortality were determined (n = 1565 piglets). TCG piglets had a lower risk (p < 0.001) of pulp opening than RG piglets (0.08 ± 0.31 vs. 2.67 ± 1.67 opened pulps per piglet). Mortality, growth, skin lesions and behaviour of piglets were not influenced by treatment (p > 0.05). This study showed that both teeth-grinding methods led to pulp openings. If teeth grinding cannot be avoided on a farm, using the teacup grinding head is recommended concerning animal health and welfare.

Material Removal Mechanism and Force Modeling in Ultrasonic Vibration-Assisted Micro-Grinding Biological Bone

Micro-grinding with a spherical grinding head has been deemed an indispensable method in high-risk surgeries, such as neurosurgery and spine surgery, where bone grinding has long been plagued by the technical bottleneck of mechanical stress-induced crack damage. In response to this challenge, the ultrasound-assisted biological bone micro-grinding novel process with a spherical grinding head has been proposed by researchers. Force modeling is a prerequisite for process parameter determination in orthopedic surgery, and the difficulty in establishing and accurately predicting bone micro-grinding force prediction models is due to the geometric distribution of abrasive grains and the dynamic changes in geometry and kinematics during the cutting process. In addressing these critical needs and technical problems, the shape and protrusion heights of the wear particle of the spherical grinding head were first studied, and the gradual rule of the contact arc length under the action of high-speed rotating ultrasonic vibration was proposed. Second, the mathematical model of the maximum thickness of undeformed chips under ultrasonic vibration of the spherical grinding head was established. Results showed that ultrasonic vibration can reduce the maximum thickness of undeformed chips and increase the range of ductile and bone meal removals, revealing the mechanism of reducing grinding force. Further, the dynamic grinding behavior of different layers of abrasive particles under different instantaneous interaction states was studied. Finally, a prediction model of micro-grinding force was established in accordance with the relationship between grinding force and cutting depth, revealing the mechanism of micro-grinding force transfer under ultrasonic vibration. The theoretical model’s average deviations are 10.37% in x-axis direction, 6.85% in y-axis direction, and 7.81% in z-axis direction compared with the experimental results. This study provides theoretical guidance and technical support for clinical bone micro-grinding.

Feasibility Study of Integrated Precision Abrasive Machining of Shaped Surfaces

The use of CNC equipment that integrates several machining operations allows the elimination of downtime resulting from setup changeovers and the clamping of workpieces in several different machine tools. More and more CNC machines and tools that allow the integration of several machining operations are appearing on the market, but there are only a few examples of these and many solutions that allow such integration for more complex operations are still missing. The aforementioned factors motivated the research work described in this paper. The purpose of the present study was to develop an innovative grinding head with different functional features for use in the process of shaped surfaces face grinding, the use of which will enable complete abrasive machining in a single mounting. The conducted tests of the grinding process showed a reduction in the values of the roughness parameters Sa (5.30, 1.12, 0.63 μm), St (31.8, 14.4, 6.72 μm), Sq (6.39, 1.46, 0.81 μm) and Spk (6.16, 0.77, 0.33 μm) and an increase in the value of the parameter Sds (393, 563, 1203 pks/mm2) on the surface after machining in two stages, first for rough grinding and then for finishing relative to the surface after the shaped milling process.

A new force-depth model for robotic abrasive belt grinding and confirmation by grinding of the Inconel 718 alloy

• A new force-depth model for robotic abrasive belt grinding is proposed considering the deformation of the contact wheel. • The mapping relationship between the grinding force and the grinding depth is obtained. • When the grinding depress depth is large, the feed force and the normal force appear obvious secondary pressure peaks. • The grinding force ratio of downgrinding (average 0.668) is smaller than that of upgrinding (average 0.724). Robotic abrasive belt grinding has been successfully applied to the grinding and polishing of aerospace parts. However, due to the flexible characteristics of robotic abrasive belt grinding and the time-varying characteristics of the polishing contact force, as well as the plastic and difficult-to-machine material properties of Inconel 718 alloy, it is very difficult to control the actual removal depth and force of the polished surface, which brings great challenges to robot automatic polishing. Therefore, the relationship between the grinding force and the grinding depth in the robotic abrasive belt grinding is analyzed in detail, the robot machining pose error model considering the deformation of the grinding head is established, and the Inconel 718 alloy machining experiment of the robotic abrasive belt grinding is designed. The mapping relationship between the grinding force and the grinding depth is obtained, and the grinding force ratio in the downgrinding and upgrinding mode is discussed. The experimental and theoretical comparisons results show that with the increase of the grinding depress depth, both the grinding depth and the grinding force show an irregular increasing trend, and the increasing trend of the grinding force (increases by about 344.44%–445.45%) is obviously greater than that of the grinding depth (increases by about 52.94%). When the grinding depress depth is large (greater than 3 mm), the feed direction force and the normal force appear obvious secondary pressure peaks at the beginning and end of grinding, which has not been seen in previous studies. In addition, regardless of whether it is downgrinding or upgrinding, the grinding force ratio decreases with the increase of the depress depth, and the grinding force ratio of downgrinding (average 0.668) is smaller than that of upgrinding (average 0.724). This study provides a reference for robotic abrasive belt grinding, and the surface quality of Inconel 718 alloy of robotic abrasive belt grinding can be further improved through the optimization of force and depth.

Speed estimation of the spindle motor of the grinding head for a high-speed precision roll grinder based on the extended Kalman filter

ABSTRACT Since installing speed sensors on the grinding head for high-speed precision roll grinders is not feasible, it is necessary to use direct torque control (DTC) without speed sensors, and its control system requires high estimation accuracy. In this paper, speed estimation methods using extended Kalman filter (EKF) and model reference adaptive system (MRAS) have been used to realise speed estimation in the DTC system of the spindle motor of the grinding head for a high-speed precision roll grinder. The simulation results showed that the EKF method has relatively high accuracy and a fast convergence speed for the estimation speed of the spindle motor of the grinding head for a high-speed precision roll grinder by comparison with the MRAS method. Moreover, the EKF method was also able to overcome the nonlinear and parameter uncertainty of the operating system of the motor and strongly immune to the noise interference of the system. Finally, the speed estimation accuracy of the motor using the EKF method had better than the MRAS method. Therefore, this work provides a general approach to applying the DTC without speed sensors for the motor and further lays a solid foundation for developing high-speed precision roll grinders.

New planetary grinding heads for restoring the surface of the thrust centers of rolling machines

A simplified technology for restoring the contact surface of the thrust centers of roll-cutting machines using planetary grinding heads is considered. The designs and schemes of planetary grinding heads with mechanical and electric feed boxes, as well as a double design are given. Keywords: grinding head, roll-cutting machine, thrust center, motor-spindle, feed box. Yakov_Liberman@List.ru, LN Gorbunova@sfu-kras.ru

Cutting performance and tool wear in laser-assisted grinding of SiCf/SiC ceramic matrix composites

Ceramic matrix composites have high hardness, so their machining requires high grinding forces that cause severe wear of the grinding head. To investigate this problem, the present study investigated the cutting performance of conventional grinding (CG) and laser-assisted grinding (LAG) of SiCf/SiC ceramic matrix composites using electroplated diamond grinding heads. Firstly, a three-dimensional transient heat transfer model based on a Gaussian heat source was developed to observe the surface and internal temperature field distributions of SiCf/SiC ceramic matrix composites subjected to laser irradiation. Secondly, the effects of laser heating temperature on the workpiece surface on the grinding forces were analysed. It was found that the axial and feed grinding forces were more than 40% lower under LAG than CG due to the removal mechanism of the SiC matrix changing from brittle fracture to ductile fracture and the oxidation reactions occurred in the SiCf/SiC ceramic matrix composites. Thirdly, the material removal mechanism was analysed by observing the morphology of machined surfaces, which showed that ductile removal from the SiC matrix occurs during LAG. Finally, it is also founded that the mean height of exposed abrasive grains from machined surface was reduced by 1.02 μm, 12.52 μm in LAG and CG respectively. The forms of wear caused by abrasive grains were studied. Under CG, the abrasive grains mainly exhibit cleavage fractures; while under LAG, micro-abrasion is the main wear form.

STUDY OF THE INFLUENCE OF THE WORKING LIQUID TEMPERATURE IN THE SPINDLE BEARINGS OF A CYLINDRICAL GRINDING MACHINE ON THE ERRORS OF ITS POSITION RELATIVE TO THE PART BEING MACHINED

The article presents the results of measurements of the ambient temperature around the working cylindrical grinding machines during the working day. The analysis of the behavior of the grinding head spindle of different cylindrical grinding machines during the work shift is performed, namely the results of experimental studies of the displacement of the front and rear ends of the grinding head spindle of cylindrical grinding machines are presented. The analysis of influence of temperature of working fluids in spindle bearings on its displacement is carried out. Possible changes in the geometric shape, namely, conicity, of parts machined on cylindrical grinding machines have been established.

Research on the Visual Guidance System of Zoning Casting Grinding Based on Feature Points

Compared to traditional rough casting grinding (RCG), the individualization of castings is very different, which makes it difficult to realize the automation of casting grinding. At this stage, the primary method is manual grinding. In this study, the regional casting grinding system based on feature points is adopted to achieve the personalized grinding of castings and improve the grinding efficiency and the automation level of the manufacturing process. After preprocessing the point cloud, the fast point feature histogram (FPFH) descriptor is used to describe the features of each region and construct the local template. The position of the local region is obtained by template matching. The random sample consensus (RANSAC) algorithm is used to calculate the plane and fit the point cloud to obtain the contact point trajectory of the grinding head. Then, according to different polishing methods, different polishing poses are generated. The simulation experimental results show that the system has good adaptability, and the consistency of finished products is good.

EXPERIMENTAL STUDIES OF WORKING FLUID TEMPERATURE IN SPINDLE BEARINGS OF CYLINDRICAL GRINDING MACHINES

Experimental studies of the temperature of the working fluid in the spindle bearings of the grinding head of circular grinding machines of different models have been performed. The conditions of the performed experimental researches are described. The influence of ambient temperature and design parameters of grinding head parts on the change of working fluid temperature in the front and rear spindle bearings is considered. It is experimentally proven that the difference in fluid temperatures in the front and rear bearings depends on the operating time of the machine. The time interval of machine operation when thermal equilibrium occurs is set.

Flow field characteristics and experimental research on inner-jet electrochemical face grinding of SUS420J2 stainless steel

Electrochemical grinding (ECG) is processed by the combination of dissolution and grinding. It is very suitable for the processing of difficult-to-cut stainless steel, but its processing performance is restricted by the matching effect of dissolution and grinding. In this work, the processing of the torus surfaces of the stainless steel shaver cap was taken as the research object. A flow field model including the through-hole structure and the rotation of the grinding head was proposed to optimize the flow field distribution and promote the uniform dissolution of materials. The flow field simulation results showed that the rotational flow formed by the high-speed rotation prolonged the electrolyte flow path and was not conducive to the discharge of electrolytic products, and the reasonable selection of the diameter and distribution of the through-hole could reduce the velocity difference. The effects of rotational speed, feed rate, and inlet pressure on the flatness and surface roughness of the torus surfaces were experimentally investigated, and a better matching effect of dissolution and grinding was obtained. Moreover, the experimental results showed that the inner-jet ECG had a good prospect in the batch processing of high-hardness stainless steel parts.

A Compliant Force Control Scheme for Industrial Robot Interactive Operation

To meet the enormous demand for smart manufacturing, industrial robots are playing an increasingly important role. For industrial operations such as grinding 3C products, numerous demands are placed on the compliant interaction ability of industrial robots to interact in a compliant manner. In this article, an adaptive compliant control framework for robot interaction is proposed. The reference trajectory is obtained by single-point demonstration and DMP generalization. The adaptive feedforward and impedance force controller is derived in terms of position errors, and they are input into an admittance controller to obtain the updated amount of position deviation. The compliant interaction effect is achieved, which is shown that the grinding head fits on the curved surface of a computer mouse, and the interaction force is within a certain expected range in the grinding experiment based on the performance an Elite robot. A comparative experiment was conducted to demonstrate the effectiveness of the proposed framework in a more intuitive way.