Grinding Machine Tool Research Articles

A practical postprocessor with compensation of tool clamping errors for five-axis tool grinding machine

The runout of the cutting edge significantly affects the cutting force, wear, and the process stability. Generally, the postprocessor of five-axis tool grinding machine ignores the clamping error of blank. Hence, this paper developed a postprocessor method with compensation of tool clamping errors to minimize runout of cutting edge for tool grinding machine. This method includes the kinematic model and the measurement model of clamping error for the tool grinding machine. This kinematic model converts CL data into NC data and converts NC data into CL data. The measurement model for measuring and calculating the clamping error of blank. The clamping error was inputted into the kinematic model of machine to compensate the clamping error. The solution strategy of the kinematic model was built, and is suitable for five-axis tool grinding machine. A postprocessor was subsequently developed according to the algorithm presented. Finally, the effectiveness of postprocessor was confirmed by the grinding experiment.

An on-machine measurement technique with sub-micron accuracy on a low-precision grinding machine tool

The on-machine measurement system can effectively improve the machining efficiency and accuracy of the optics in the grinding stage, but the common grinding machine has large geometric errors and ambient temperature errors, which are the key factors restricting the accuracy of on-machine measurement. In this paper, a high-precision error separation technique including geometric error separation and temperature error separation is proposed to achieve sub-micron level measurement accuracy in the grinding stage. The on-machine measurement system is built based on the color confocal sensor. A sensitive error model is established based on Abbe's principle and multi-body dynamics, and the geometric error separation with zero Abbe's error is achieved by a high-precision reference mirror. Then the temperature error influence model is established based on the scanning path, and the temperature error separation method based on the auxiliary profile line is proposed according to the temperature error model. Finally, it is verified through experiments that after error separation, the measurement accuracy of the on-machine measurement system is improved from tens of micron to sub-micron, which exceeds the measurement accuracy of ordinary coordinate measurement machines (CMMs), and can effectively improve the machining accuracy and efficiency in the grinding stage.

Applying the MIMO BP Neural Network and Cloud-Based Monitoring of Thermal Behavior for High-Speed Motorized Spindle Units

Understanding the temperature–working condition relationship is crucial for optimizing machining processes to ensure dimensional accuracy, surface finish quality, and overall spindle longevity. Monitoring and controlling spindle temperature through appropriate cooling systems and operational parameters are essential for efficient and reliable machining operations. This paper presents an in-depth analysis of the thermal equilibrium and deformation characteristics of a high-speed motorized spindle unit utilized in grinding machine tools. Through a series of thermal equilibrium experiments and meticulous data acquisition, the study investigates the nuanced influence of various working conditions, including spindle speeds, coolant types, and coolant flow rates, on spindle temperatures and thermal deformations. Leveraging the power of Artificial Neural Networks (ANNs), predictive models are meticulously developed to accurately forecast spindle behavior. Subsequently, the models are seamlessly transitioned to a cloud computing infrastructure to ensure remote accessibility and scalability, facilitating real-time monitoring and forecasting of spindle performance. The validity and reliability of the predictive models are rigorously assessed through comparison with experimental data, demonstrating excellent agreement and high accuracy in forecasting spindle thermal behavior. Furthermore, the study underscores the critical role of key working condition variables as precise predictors of spindle temperature and thermal deformation, emphasizing their significance in optimizing overall spindle efficiency and performance. This comprehensive analysis offers valuable insights and practical implications for enhancing spindle operation and advancing the field of grinding machine tools.

Ultra-precision time-controlled grinding for flat mechanical parts with weak stiffness

High-precision flat mechanical parts are widely used, such as in aerostatic bearing, which requires a rather high machining precision. Due to large size, low stiffness and other machining problems, traditional ultra-precision grinding machine tool cannot directly achieve the final precision, so manual grinding is necessary to meet the manufacturing requirements, resulting in low efficiency. Based on the computer-controlled optical surfacing (CCOS) method and the flexible grinding process, the time-controlled grinding method (TCG) is proposed to achieve quantitative material removal at each position on the workpiece. Combined with the material removal mechanism, the removal function with good linearity and stability is extracted by controlling corresponding parameters. By applying a novel measuring and processing method of surface data with high precision and high efficiency, the flatness error and parallelism error are accurately obtained and used as grinding reference to carry out the time-controlled grinding experiment on one spacer ring with a diameter of 190 mm. The final flatness error converges from 1.5–2 μm to 0.6–0.7 μm and parallelism error converges from ~2 μm to ~0.6 μm, while the roughness converges from 273 nm Ra to 65 nm Ra, achieving the goal of ultra-precision digital machining of submicron level. The machining precision is better than traditional ultra-precision grinding machine tool, and the potential for time-controlled grinding method of ultra-precision machining in flat mechanical parts especially with low stiffness is verified.

Pivotal errors identification of the face gear worm grinding machine tool with a piecewise sensitivity analysis

As one of the main error sources, geometric errors greatly affect the machining accuracy of the face gear worm grinding machine tool. To reveal the mapping rules between the geometric errors and the tooth surface errors (TSEs) of face gear, the tool comprehensive error model (TCEM) and the tooth surface error model (TSEM) were successively established. The TCEM expressed the relationship between 41 geometric errors of the machine tool and 6 tool comprehensive errors (TCEs) of the tool while the TSEM expressed the relationship between 6 TCEs and 3 TSEs. Then, using the improved Sobol method, a piecewise sensitivity analysis was carried out by calculating the sensitivity indexes of the input of the TCEM and TSEM individually. Finally, the joint sensitivity indexes were calculated and the pivotal geometric errors were identified. By modifying the pivotal geometric errors in each TSE direction separately, all the main error reduction rates (ERR) are greater than 70%. Besides, by modifying all the pivotal geometric errors, the maximum values of 3 TSEs are reduced by 73.7%, 74.7% and 86.96%, respectively, and the minimum values are reduced by 57.1%, 71.79% and 76.19%, respectively, confirming the validity of the identified results.

Machines to Manufacture a Spectrum of Parts

T&G Engineering invests in the latest technology to power growth; Punch and die manufacturer AW Precision Ltd finds the ideal grinding machine; new hybrid milling and grinding machine tool solution reduces process times; plus, Studer unveils the S100

Cutting edge preparation with elastic bonded diamond grinding wheels: Influence of the interaction of metalworking fluid and grinding wheel on the grinding wheel properties and preparation result

The cutting edge preparation with elastic bonded superabrasive grinding wheels enables the accurate manufacture of customized cutting edges. This process necessitates highest accuracies of the machine and the kinematics. Up to now, no systematic investigations on the interaction of the metalworking fluid and the grinding wheel were done; those could alter the properties of the grinding wheel, and as a consequence the result of cutting edge preparation. The influence of this interaction on cutting edge preparation is investigated in this study using two different experimental setups. One setup where the grinding wheels interacted with the metalworking fluid in an aging chamber to speed up the aging process and one setup directly in a tool grinding machine, in which the grinding wheels were also applied for cutting edge preparation at different stages of aging. In the aging chamber, the interaction takes place under elevated metalworking fluid temperatures to accelerate possible interaction effects. The results revealed an increase in the diameter, width and weight of the grinding wheels and a reduction in hardness. These changes were more pronounced under the elevated temperatures in the aging chamber. This in turn resulted in a significant alteration in the geometry of the prepared cutting edges, which was not observed when the grinding wheels interacted with the metalworking fluid in the tool grinding machine. As a general result, to keep the properties of the grinding wheels approximately constant, continuous dressing cycles should be carried out. In addition, the grinding wheels should be stored in dry conditions when not using them. In this way, specific cutting edge geometries can be manufactured reproducibly.

Process-related characteristic–based topography evaluation of wear conditions on grinding wheels

Non-productive auxiliary processes affect the single part and small badge production of milling tools. The key production process grinding is inevitably linked to the auxiliary conditioning process. The time demand of those process steps decreases the overall productivity of the manufacturing process. However, today the machine operator decides on conditioning cycles individually by the use of experience. Until today, there is no objective data based approach available that supports the initiation of these conditioning processes or the adaption of the grinding process itself in order to improve its process efficiency. For this purpose, a process-related topography evaluation method of the grinding wheel surface is developed within this study. For the measurement, an optical method based on laser triangulation is used. The measurement system is implemented into a common tool grinding machine tool. In addition, characteristic topography values are defined that show the wear conditions of the grinding tool. Moreover, the data is summarized in a database of wear conditions. The developed measurement method can save grinding and dressing tool resources, process times and minimizes scrap parts. In addition, an adaptation of the process and a targeted launch of auxiliary processes can be enabled. The novel characteristic-based topography measurement creates the opportunity to enhance the tool life of the grinding wheels up to 30% without losing productivity.

Kinematic Planning and In-Situ Measurement of Seven-Axis Five-Linkage Grinding and Polishing Machine Tool for Complex Curved Surface

An integrated polishing and in-situ measurement machine tool with seven-axis and five-linkage is developed for manufacturing and measuring the complex curved surface such as blisk. Firstly, this paper introduces the structure and configuration of the machine tool. Then, the kinematic analyses of the polishing side and measuring side of the machine tool are carried out respectively and the inverse kinematic solutions of them are derived. The motion of each axis can be calculated based on the tool location of the complex curved surface through the inverse kinematic solution. Aiming at the in-situ measurement of parts with complex curved surfaces, the forward kinematic solution, the processing of measured data of blade surface and the calculation algorithm of the machining allowance are developed in the paper. Finally, the above algorithms are verified by polishing the experimental stainless-steel sample.

Tehnologija izrade profilnih koturastih glodala 3+2 osnim brušenjem na horizontalnom obradnom centru

The paper presents the technology of making brazed shaper milling cutters and with special reference to 5-axis grinding process (making of profile blades) on CNC grinding machine tool. Based on the analysis of the kinematics of the 5-axis grinding process, a new concept of profile milling tool production by a 3+2 axis grinding process on horizontal milling center was established. By Applying new concept, one tooth of profile tool was machined by grinding process. By obtained results, new approach for manufacturing of profile milling tools was verified.

Experimental study on the reliability and the precision maintenance of the ultra-precision grinding machine based on the key subsystem platforms

The development of high-reliability, high-precision large-scale CNC ultra-precision grinding machines is essential for the efficient processing and manufacturing of large-diameter optical components. In this paper, we studied the reliability and the precision-maintenance of the ultra-precision grinding machine tool experimentally. First, the subsystems with poor performance were identified based on former operating data, which turned out to be the hydrostatic spindle subsystem and the feed subsystem. Then, we set up specific experimental platforms for these two subsystems to study the thermal deformation and thermal characteristics. The temperature difference between the inflow and outflow oils of the hydrostatic systems is used as the key parameter to model the accuracy evolution. Our results may provide a method to reveal the relationship between the thermal characteristics and the operating parameters of the subsystems, and therefore compensate the thermal error of the whole ultra-precision grinding machine.

Investigation of cycle time behavior in the robotic grinding process

The production of power transmission components such as gears and bearing rings involves precision finishing of highly specialized and dedicated precision grinding machine tools. Six degree-of-freedom (6-dof) articulated arm industrial robots are less expensive and more versatile than precision grinding machines because they can be readily reconfigured for a variety of production tasks including precision grinding of free-form surfaces. However, the high compliance of such robots poses a challenge in high-precision operations, particularly as it relates to the overall cycle time of the process. The paper presents an analysis of the effects of robot compliance and grinding parameters on the cycle time of a precision grinding process. Specifically, a process model for robot-workpiece interaction and grinding process cycle time is developed. This model is used to analyze the behavior of a face grinding process cycle. The results show that for a given robot stiffness, minimizing the face grinding cycle time requires the process to be operated at the highest achievable wheel speed and infeed rate with a wheel of higher hardness. The paper also shows that a 6-dof robot offers the flexibility of modifying the Cartesian stiffness at the end effector by varying the robot pose, which is difficult to achieve in conventional grinding machines. This capability, along with the process cycle time model, permits optimization of process cycle times for precision grinding of surfaces, including free-form surfaces, using 6-dof robots.

An optimized algorithm and the verification methods for improving the volumetric error modeling accuracy of precision machine tools

Referring to the error modeling technology used in precision machine tools, it is difficult for machine tool builders to understand the effects of the theoretical modeling accuracy on the precision machining in the designing stages, where error components are represented by parameters. Therefore, this study is proposed to overcome certain theoretical calculation errors for a parametric form of volumetric error modeling and to examine verification method for judging the modeling precision. Based on the mathematical theory, a novel optimized algorithm is presented, as well as its verification methods. With the two new methods, it is effective to identify theoretical calculation errors and verify the accuracy of error modeling. Meanwhile, the proposed algorithm, with a form grinding machine tool being as an illustration example, is tested and validated by means of numerical simulations in the Matlab. The results reveal that the modeling accuracy of the error characteristic matrix is improved and enhanced by the algorithm, and the two verification methods can check the veracity of parametric modeling precision in different ways. Especially, the second method can check and isolate quantitatively the theoretical calculation errors. At the same time, it is a theoretical guidance for choosing a suitable treatment to meet the accuracy of an error model represented by parametric variables during iterations of the characteristic matrices. These two prediction veracity and uncertainty of the modeling precision can be evaluated. Furthermore, the algorithm and checking methods can be extended to ultra-precision multi-axis machine tools.

Virtual reality training platform for a computer numerically controlled grinding machine tool

Virtual reality training platform for a computer numerically controlled grinding machine tool

Study of Complex Helical Drill with a “S” Type Chisel Edge Tip Orient to Carbon Fiber Reinforced Plastics

In this paper, a complex helicoids’ drill tip of “S” type chisel edge grinded with a three‐parallel universal CNC grinding machine tool is carefully studied to obtain the optimum drill bit tip geometry parameters. The effects of experimental parameters, such as apex angle, chisel edge incline angle, and structure circumference rear angle, on the quality of the drilling hole and the machining force were studied from the orthogonal experiment compared with the ordinary drill bit. The range of technological parameters are confirmed which should be used during the drilling process of carbon fiber reinforced plastics (CFRP) in order to realize the reduction of cutting defects such as cutting force and spurs. The effect of spindle speed and feed on the drilling behaviour of the experiment using optimum complex helicoids’ drill tip is also analyzed. It is found that the feed has a great influence on the drilling axial force and the spindle speed has little influence on axial force, but great influence on torque.

Virtual reality training platform for a computer numerically controlled grinding machine tool

In-depth training of machine tool (MT) operators is crucial to avoid machine damage due to faulty operation. However, machine-hours are costly and during the training, the MT is unavailable for regular production purposes. Here, virtual real-size models offer a solution by providing basic operation principles to future operators. In this context, it is yet unknown whether a virtual teaching enhanced by real walking is similar to a real teaching scenario regarding the learning efficiency and long-term memory retention. This paper describes a study comparing the learning efficiency of a virtual training session with traditional instructions on a real MT. The learning success of both training groups is objectively and subjectively assessed on a real MT a week later. In this assessment, the task completion time and the number of errors are recorded. We observed that the virtually taught group slightly outperformed trainees taught in reality regarding both objective measurements.

Effect of the cutting conditions on surface roughness during 5-axis grinding of Maraging steel MS1

This work deals with the effect of the cutting conditions and the spindle tilt on the surface roughness when grinding complex shaped surfaces of Maraging steel MS1 on an ANCA MX7 5-axis tool grinding machine. It is necessary to grind complex shaped surfaces where high surface quality is important and requested. For this experiment was selected a component with a complex shaped surface which was printed on the 3D printer machine from maraging steel MS1. Since grinding of complex surfaces is being investigated, it is necessary to use CAM software for creat-ing an NC program. The aim of this work is to study the effects of the cutting conditions on the grinding of a com-plex shaped surface in relation to the resulting surface roughness. To do this, it was necessary to design an experi-ment with the appropriate grinding technology, create a clamp, and create NC data in NX CAM software for grinding the complex shape surfaces on the part.

An efficient generation grinding method for spur face gear along contact trace using disk CBN wheel

In order to further improve the grinding efficiency of face gear, this paper presents a novel method for grinding face gear along contact trace using disk CBN wheel. Firstly, the grinding principle of face gear is studied, and the tooth surface equations of rack and gear shaper cutter are derived, thus formulating the tooth surface equation of disk CBN wheel. Secondly, considering the structure of the face gear grinding machine tool and the impact of the grinding wheel parameters on the face gear tooth surface, the disk CBN wheel configuration is proposed, and the calculation method of the tool position of the face gear grinding is established. Thirdly, according to the structural characteristics of the grinding wheel, the tooth surface contact trace of the face gear is designed, and the face gear development grinding processing method along the tooth surface contact traces is presented. Finally, a test of grinding spur face gear with disk CBN wheel is carried out on a laboratory-made five-axis face gear processing machine. The test results verified the correctness of the face gear grinding. Compared with the dish wheel for grinding face gear, the grinding method proposed in this paper can further improve the grinding efficiency of face gear. This method will break new ground for the engineering application of the face gear.

Energy Consumption Prediction Model of SiCp/Al Composite in Grinding Based on PSO-BP Neural Network

As the typical particle-reinforced aluminum matrix composite, SiCp/Al composite has low density, high elastic modulus and high thermal conductivity, and is one of the most competitive metal matrix composites. Grinding is the main processing technique of SiCp/Al composite, energy consumption of the grinding process provides guidance for the energy saving, which is the aim of green manufacturing. In this paper, grinding experiments were designed and conducted to obtain the energy consumption of the grinding machine tool. The Particle Swarm Optimization (PSO) BP neural network prediction model was applied in the energy consumption prediction model of SiCp/Al composite in grinding. It showed that the Particle Swarm Optimization (PSO) BP neural network prediction model has high prediction accuracy. The prediction model of energy consumption based on PSO-BP neural network is helpful in energy saving, which contributes to greening manufacturing.

Development of an oscillating grinding machine tool based on error analysis

Oscillating grinding machine tool is the core equipment when machining crankshaft pin journal, which directly determines the final quality. This paper describes the development of an oscillating grinding machine tool based on error analysis. First, the error analysis of oscillating grinding for crankshaft pin journal is carried out, including the effect on machining accuracy caused by each error and corresponding error sensitivity. The results show that the tracking error of X-axis has the greatest influence on the grinding accuracy of pin journal, thus, the grinding carriage feed system is the critical component of an oscillating grinding machine tool, which should be given priority during the development process. Next, the development of an oscillating grinding machine tool is described. The whole structure is given, and the grinding carriage feed system is emphatically presented involving drive mode and assembly method. Other components of the oscillating grinding machine tool are also introduced. Finally, some grinding experiments are performed on the prototype, and the results show that all workpieces are qualified under different conditions, which verify the performance of the developed oscillating grinding machine tool.