Grinding System Research Articles

Effect of Assembly Errors on Ground Tooth Surface Deviations for Large-Scale CNC Gear Profile Grinding Machines

Assembling plays a significant role in the performance of large-scale CNC gear profile grinding machines. An approach in the deviation evaluation of ground tooth surfaces taking into account assembly errors is proposed in this paper. Based on the error transmission chain of the profile grinding system and the conjugate motion relationship between the grinding wheel and the workpiece, the ground tooth surface model including assembly errors was established using the surface envelope method. Then, the effect of assembly errors on deviations of the profile grinding tooth surface was quantitatively analyzed. The optimized distribution of assembly errors and machining verifications were performed on large-scale CNC gear profile grinding machines. The results show that the proposed method is effective at ensuring ground tooth surface deviations for large-scale CNC gear profile grinding machines.

Development of Remote-controlled Robot System for Grinding

Development of Remote-controlled Robot System for Grinding

Region-Based Force Control Strategy for Improving Profile Accuracy of Blade on 7-Axis Linkage Robotic Grinding System

Region-Based Force Control Strategy for Improving Profile Accuracy of Blade on 7-Axis Linkage Robotic Grinding System

Енергоефективність системи подрібнення твердих рослинних відходів для виробництва біопаливних пелет

The production of biofuel pellets requires significant energy consumption during their production. At the primary technological stage of production: grinding of solid vegetable waste (SVW), electricity costs can be, depending on the physical and mechanical characteristics of SVW, 40… 60% of the total electricity consumed for the production of pellets. Significant losses of electric energy are observed during grinding due to uneven loading of the shredder and operation of the electric motor of its drive in constantly changing modes. This is especially true for small productions when downloading is done manually. This paper proposes a method and algorithm for determining the maximum values of the energy efficiency of the SRW grinding system for the production of biofuel pellets as a function of the load factor of the electric motor of the working machine at different values of applied voltage. As a result of research of an asynchronous electric motor with a nominal power of 4 kW SVW shredder during its operation according to the loading schedule during the eight-hour work shift provided by the farm, it was determined that control of applied voltage at variable loads will reduce energy consumption and increase the energy efficiency of the shredder by 4…6%. According to the results of research, it is proposed to develop a device for controlling the magnitude of the applied voltage at variable loads, the implementation of which will reduce energy consumption by the shredder drive. The proposed technique can also be used in the diagnosis of the electric motor of the shredder, which is in the process of operation of the technological line of production of pellets.

Production and Characterization of Cellulose Nanofiber Slurries and Sheets for Biomedical Applications

Cellulose nanomaterials are produced employing a multitude of methodologies including electrospinning, bacterial generation, acid digestion, and a variety of mechanical defibrillation techniques; the morphology of the nanomaterial produced is specific to the production process. Feedstocks range from various forms of woody biomass, to fungi, and have a great impact on the resulting product. The mechanical defibrillation technique, such as that employed in the present work, continuously breaks down cellulose fibers suspended in water via segmentation and defibrillation through grinding and refining. The process is typically operated until a desired level of fines is achieved in the resultant slurry of cellulose nanofiber (CNF), alternatively known as cellulose nanofibril. Mechanical defibrillation processes can be built to produce several liters in a small batch system or up to tons per day in a continuous pilot scale refiner system. In the present work a continuous system was developed with the capacity to produce 14 L of cellulose nanofiber slurry with consistent specifications and in a manner compliant with GMP/GLP protocols in order to be amenable to biomedical applications. The system was constructed within an ISO class 7 cleanroom and refining was performed on bleached softwood pulp suspension in purified water. This manuscript details the continuous grinding system, the processes employed to produce cellulose nanofiber, and characterizes the resultant cellulose nanofiber slurry and sheets formed from the slurry.

Rigid–flexible coupling dynamics analysis with joint clearance for a 5-DOF hybrid polishing robot

SUMMARYConsidering the polishing requirements for high-precision aspherical optical mirrors, a hybrid polishing robot composed of a serial–parallel manipulator and a dual rotor grinding system is proposed. Firstly, based on the kinematics of serial components, the equivalent load model for the parallel manipulator is established. Then, the elastodynamic model of kinematic branched-chains of the parallel manipulator is established by using the spatial beam element, and the rigid–flexible coupling dynamic model of the polishing robot is obtained with Kineto-elasto dynamics theory. Further, considering the dynamic properties of the joint clearance, the rigid–flexible coupling dynamic model with the joint clearance for the polishing robot is established. Finally, the equivalent load distribution of the parallel manipulator is analyzed, and the effect of the branched-chain elasticity and joint clearance on the motion error of the polishing robot is studied. This article provides a theoretical basis for improving the motion accuracy and dynamic performance of the hybrid polishing robot.

Crushing characteristics of different minerals by cylindrical ball mill in cascading motion state

During the grinding process of the impact and abrasion actions synchronously coexist and continuously occur, the two actions may exert forces in different areas and transform to each other periodically. So it is difficult to characterize the respective crushing characteristics of the impact and abrasion actions. Based on the kinematics theory of grinding media, to ensure the grinding medium to be in cascading motion state in which minerals are crushed by only abrasion action of medium, to investigate the crushing characteristics of three kinds of minerals of quartz, pyrrhotite, and pyrite. Moreover, the difference in the ability to resist the crushing in the grinding process and the influence of feed sizes on the crushing were investigated by analyzing and comparing the breakage rate of the different minerals and the yield of specific product size - t 10 value under different test conditions. The research results indicated that the grinding resistance of quartz is the strongest, followed by pyrite and pyrrhotite. Besides, a smaller feed size resulted in a more grinding and crushing effect on the minerals. Therefore, during production, the grinding system should be adjusted according to the change in the material property to prevent over-grinding.

Active Compliant PID Learning Control for Grinding Robots

This article proposes a Proportional, Integral, and Derivative (PID) learning controller for rigid robotic disk grinding mechanism. It has been observed that the stiffness of the robotic arm for a grinder has a direct correlation with the sensitivity of the grinding forces. It is also drastically influenced by the end-effector path tracking error resulting in limited accuracy of the robot. The error in robot’s accuracy is also increased by external interferences, such as surface imperfections and voids in the subject material. These errors can be mitigated via efficient feedback. In the proposed methodology, the controller gain is tuned by implementing a learning-based methodology to PID controllers. The learning control for the robotic grinding system helps by progressively decreasing error between the actual grinded paths and required trace. Experimental results demonstrate that as the grinder machines the required path iteratively, its grinding accuracy improves due to the learning algorithm.

Prediction of Surface Roughness of Abrasive Belt Grinding of Superalloy Material Based on RLSOM-RBF.

It is difficult to accurately predict the surface roughness of belt grinding with superalloy materials due to the uneven material distribution and complex material processing. In this paper, a radial basis neural network is proposed to predict surface roughness. Firstly, the grinding system of the superalloy belt is introduced. The effects of the material removal process and grinding parameters on the surface roughness in belt grinding were analyzed. Secondly, an RBF neural network is trained by reinforcement learning of a self-organizing mapping method. Finally, the prediction accuracy and simulation results of the proposed method and the traditional prediction method are analyzed using the ten-fold cross method. The results show that the relative error of the improved RLSOM-RBF neural network prediction model is 1.72%, and the R-value of the RLSOM-RBF fitting result is 0.996.

Research on Influence of the Internal Parameters of V-Type Separator on the Separation Efficiency

The performance of the grinding system is affected by the performance of the separator. It is significant to study the efficiency of the milling system for reducing the energy consumption of the whole grinding system. By changing the baffle plate parameters, the Distribution Law of the flow field inside the separator was analyzed, and the most reasonable structure parameters of the separator were obtained. By using the gas-solid two-phase model and the DPM discrete phase model, the classification efficiency and the total efficiency of the separator are calculated. It is verified that the parameters of the baffle plate are important factors to improve the efficiency of powder separation.

Accurate estimation of workpiece dimension in plunge grinding without sizing gauge

In the cylindrical grinding process, the residual grinding allowance is left owing to the rubbing of the abrasive grains and the elastic deformation of the grinding system caused by the large normal grinding force. Therefore, a sizing gauge is generally used to monitor the workpiece diameter during the process. However, the sizing gauge disturbs the grinding operations, such as loading and unloading the workpiece. In this study, a new method for estimating the grinding stock of a ground workpiece is proposed. In the proposed method, the grinding stock can be estimated without a sizing gauge. The removed volume of the workpiece can be calculated from the power consumption of the wheel motor, which is easily measured. Before the grinding experiments, the specific grinding energy is determined from several grinding results. During the grinding process, the grinding stock of the ground workpiece was estimated using the determined specific grinding energy. It was confirmed that the grinding stock could be accurately estimated under several grinding conditions.

Designed a Passive Grinding Test Machine to Simulate Passive Grinding Process

Passive grinding is a high-speed rail grinding maintenance strategy, which is completely different from the conventional rail active grinding system. In contrast to active grinding, there is no power to drive the grinding wheel to rotate actively in passive grinding. The passive grinding process is realized only by the cooperation of grinding pressure, relative motion, and deflection angle. Grinding tests for passive grinding can help to improve the passive grinding process specifications and be used for the development of passive grinding wheels. However, most of the known grinding methods are active grinding, while the passive grinding machines and processes are rarely studied. Therefore, a passive grinding test machine was designed to simulate passive grinding in this study. This paper gives a detailed description and explanation of the structure and function of the passive grinding tester. Moreover, the characteristics of the grinding process and parameter settings of the testing machine were discussed based on the passive grinding principle. The design of a passive grinding test machine provides experimental equipment support for investigating passive grinding behavior and grinding process.

Robot welding seam online grinding system based on laser vision guidance

Robot welding seam online grinding system based on laser vision guidance

Research on the method of skateboard edge grinding by combination of robot and pneumatic constant force grinding device

The paper presents a method of robot skateboard edging grinding based on pneumatic constant force device. To solve the problem of modeling and complex algorithm of robot end active compliance control during the grinding process, a hybrid position/force control is proposed by controlling position and force separately. That is, a kind of 2 degrees of freedom pneumatic constant force grinding device is designed to realize the constant force control in the horizontal and vertical directions, while a robot is used only for position control. Then a fuzzy PID control algorithm is proposed for smooth grinding based on the dynamic modeling of the grinding device. Experiments show that the use of fuzzy PID can effectively improve the dynamic adjustment performance of the pneumatic constant force grinding system and reduce the steady-state error. Compared with normal PID, fuzzy PID reduces the step response adjustment time of the grinding system from 400ms to within 200ms. In addition, when the constant force control is disturbed, the response adjustment time is less than 100ms and there is no oscillation, and the standard deviation of the grinding force is within 1N, which has good robustness and fulfills the requirements of edging control.

MECHATRONIC TECHNOLOGICAL SYSTEM INFORMATION SUPPORT

The article focuses on a new way to solve the problem of cutting processing due to the appearance of a wide range of super-hard and hard-to-machine structural materials for aircraft, automobile, ship and engine construction, as well as for spacecraft, medi-cine (orthopedics, dentistry), nuclear and military equipment. Such materials have an organized regular structure, high strength, super hardness. As a result, there is a problem of defect-free machining of these materials without damaging their balanced structure. The article describes a new approach and formulates innovative principles for creating a new class of mechatronic technological systems for precision machining of parts made of these materials using the example of drilling small diameter deep holes. The core of the mechatronic technological systemis a mechatronic parametric stabilizer of the power load on the cutting tool. The mechatronic tech-nological systemprovidesa program task, automatic stabilization and maintenance in the tracking mode of the power load on the cutting tool with “disturbance control”. For example, in the technological cycle of drilling smalldiameter holes, such a system pro-tects the drillbits frombreakage. An integrated technological system is proposed with the following three levels of control: intelli-gent (upper), adaptive (middle) and robust (lower). The basis of the multi-level system is a high-speed robust automatic control sys-tem “by thedisturbance”. The disturbance is the load torque, which is either automatically stabilized, or tracked whensetting a pro-gram from a computer, or changes according to the program that sets the mechatronic technological systemthe functioning(opera-tion)algorithm. This algorithm can vary widely with different methods of machining parts by cutting(grinding), including shaping free 3D surfaces according to their digital models. The mechatronic technological systemproposedis easily integrated into the cut-ting (grinding) system of CNC machines, expanding their capabilities by transferring the standard control program of the CNC to a higher level of the control hierarchy. This allows machining any complex-shaped parts, including “double curvature”parts, namely impellers, turbine blades, rowing screws, etc.

TECHNOLOGICAL FIXTURES FOR MACHINING LARGE-SIZED THIN-WALLED SHELLS OF COMPLEX PROFILE

The paper analyzes the structure of technological fixtures for the positioning and fixing of large-sized thin-walled pyroceram shells as a factor affecting the dynamic characteristics of the grinding system. The solution to the problem of ensuring the dynamic stability of the «mandrel-workpiece» subsystem is necessary to increase the efficiency of shell machining in present conditions. Studying the vibrations frequency spectrum of the technological system during grinding has made it possible to determine their sources. The magnitude and frequency of vibrations depend on the mandrel structure - the clamping fixture. The study results are the requirements for a new mandrel structure, considering the dynamic stability of the technological system.

A study on intelligent grinding systems with industrial perspective

The digitization thrust on high-value manufacturing and services opens up new opportunities for ensuring total system uptime, reliability, and efficiency particularly for mission-critical high-value assets. The digitization process evolves intelligent manufacturing systems (IMS) which transforms maintenance into predictive reliability for achieving consistent quality throughout manufacturing process. This article unveils the intelligent grinding systems (IGS) for challenging grinding applications. In order to provide a better chance for value addition, previous work has been scrutinized extensively in the following aspects: grinding models, process design algorithms, and process monitoring. This then leads into an analysis of various previously designed IGS. The main focus, especially in the early 2000s, was mainly database development and parameter selection, which then shifted to process monitoring and control as particular technology advances were made. In the various goals that were investigated, it was evident that researchers were aiming for an online real-time system. This notion was driven by the advances in artificial intelligence and improved monitoring sensors, for example, acoustic emission sensors and even other unusual sensors like microphones for more economical and improved data collection and analysis. Although tremendous strides have been made, a substantial amount of work is still required in achieving a full-fledged real-time intelligent grinding system. The comprehensive findings on IGS system concludes that the real-time process update has been improved from few hours to milliseconds.

The hybrid force/position anti-disturbance control strategy for robot abrasive belt grinding of aviation blade base on fuzzy PID control

The high-quality grinding of the aviation blade components with the industry robot presents tremendous challenges because of the complexity of blade surface. The hybrid force/position anti-disturbance control strategy is developed base on fuzzy PID control to improve the quality of grinding aviation blades. Firstly, according to gravity compensation technology, the perception of contact force is discussed to solve the contact force between the blades and abrasive belt machine. Then, the hybrid force/position anti-disturbance control strategy is designed to ensure the stability of robot automatic grinding system. The speed gain loop and the dual fuzzy PID control are introduced to enhance the anti-disturbance ability of the control system. Meanwhile, the analysis of stability and steady-state error for force control loop are performed to prove the validation of the feasibility of control system. Eventually, the simulation and experiments are carried out on the robot automatic grinding system. The experimental results reveal that the proposed control strategy can achieve better control effect and grinding quality compared with the traditional PID control.

Research on double-rotor dynamic grinding model and simulation algorithm for crankshaft main journal

Crankshaft is a core part of automobile engine to bear impact load and transmit power. Precision grinding is the most important machining method to achieve high precision of crankshaft main journal. Although many scholars have established various simulation models in the field of cylindrical grinding, it is difficult to carry out effective quantitative simulation for a given crankshaft main journal grinding system. Aiming at the shortcomings of the existing models, a double-rotor dynamic model is proposed, which considers the interaction between the grinding wheel and the main journal, and iterative algorithm is adopted to simulate material removal and roundness change in the grinding process of the main journal. The normal force between grinding wheel and the main journal is defined in detail in the algorithm, which is closer to the actual grinding process. For a given crankshaft grinding system, different grinding strategies of the main journal are quantitatively simulated by using the model. The proposed model and algorithm are validated by experiments, which can provide a basic model for the further study of the crankshaft cylindrical grinding system.

Food Safety and Halal Risk Mitigation in Fish Crackers Supply Chain with FMECA and AHP

With the development of the times, people are increasingly aware that food is safe for consumption. Throughout the food supply chain process, there are many risks of food safety from being safe to being unsafe. This study aims to analyze food safety and halal risk mitigation in the supply chain, which consists of identifying food safety risks throughout the supply chain process, measuring food safety risks in the supply chain, determining the most critical value for risks that arise in food safety, and determining food safety risk mitigation measures. The object used is the supply chain of fish cracker companies in the Buduran area, Sidoarjo. Data processing was performed using FMECA and AHP methods. The results showed that the most critical risk lies in the management of the meat grinding system with a value of 0.60494 where the influencing factors are the absence of halal certification on the product and not implementing food safety standards, so that mitigation measures are carried out, namely evaluating and fostering manpower planning and job analytic.