Monitoring Grinding Wheel Redress-life Using Support Vector Machines

Condition monitoring is a very important aspect in automated manufacturing processes. Any malfunction of a machining process will deteriorate production quality and efficiency. This paper presents an application of support vector machines in grinding process monitoring. The paper starts with an overview of grinding behaviour. Grinding force is analysed through a Short Time Fourier Transform （STFT） to identify features for condition monitoring. The Support Vector Machine （SVM） methodology is introduced as a powerful tool for the classification of different wheel wear situations. After training with available signal data, the SVM is able to identify the state of a grinding process. The requirement and strategy for using SVM for grinding process monitoring is discussed, while the result of the example illustrates how effective SVMs can be in determining wheel redress-life.

RESEARCH ON MODELING AND CHARACTERISTICS OF THE SPINDLE DYNAMIC COUPLING ABSORBERING SYSTEM OF A SUPER-PRECISION SURFACE GRINDING MACHINE

The bearing is described by constrain matrix, and the spindle system of a NCsurface grinding machine is simplified as elastic-coupling beam, then modal synthesis method is usedto establish the dynamic model of beam. Moreover, the response of the end of rotor is analyzed, andthe natural frequency, principle mode and other dynamic characteristics of the coupling system arestudied, the law of bearing stiffness to coupling frequency and amplitude of rotor is also found.Finally, according to the actual condition, a dynamic absorber is designed. The simulation andexperimental results show that the amplitude of spindle can be declined effectively when the dynamicabsorber is attached.

Development of CAD/CAM system and profile measuring device for CNC grinding machine to obtain an optimal grinding speed

Cam mechanics is one of the most popular devices for generating irregular motions and is widely used in automatic equipment,such as textile machines,internal combustion engines,and other automatic devices.In order to obtain a positive motion from the follower using a rotating cam,its shape should be correctly designed and manufactured.The development of an adequate CAD/CAM system for a cam profile CNC grinding machine is necessary to manufacture high-precision cams.The purpose of this study is the development of a CAD/CAM system and profile measuring device for a CNC grinding machine to obtain an optimal grinding speed with a constant surface roughness.Three types of disk cams were manufactured using the proposed algorithm and procedures to verify effectiveness of the developed CAD/CAM system.

Theoretical Study on Non-transmission High Efficient Parallel Camber Grinding Machine

Be directed against the development trend of modern CNC grinding machine towards high precision and high efficiency, some general weaknesses of existing camber grinding machine are analyzed in detail. In order to develop new type CNC camber grinding machine that can grind complex die, and genuinely achieved accurate feed and high efficient grinding, a new type camber grinding machine is put forward, called non-transmission virtual-shaft CNC camber grinding machine. Its feed system is a parallel mechanism that is directly driven by linear step motor. Therefore, traditional transmission types, such as the ball lead-screw mechanisms, the gears, the hydraulic transmission system, etc. are cancelled, and the feed system of new type CNC camber grinding machine can truly possess non-creep, good accuracy retentiveness a wide range of feed-speed change, high kinematical accuracy and positioning precision, etc. In order to realize that the cutting motion is provided with high grinding speed, step-less speed variation, high rotational accuracy, good dynamic performance, and non-transmission, the driving technology of hollow rotor motor is applied to drive the spindle of new type grinding machine,thus leading to the elimination of the transmission parts of cutting motion. The principle structure model of new type camber grinding machine is advanced. The selection, control gist and driving circuit line of the linear step motor are expounded. The main technology characteristics and application advantages of non-transmission virtual-shaft CNC camber grinding machine are introduced.

YK 7425 GEAR GRINDING MACHINE

This is a newly developed product,CNC gear grinding machine basedon original Y 7125 A large planargear grinding machine, produced by theQinchuan Machine Tool Works. It is chieflyused for grinding the involute tooth profilesof gear-shaping cutters, gear-shaving cuttersand master gears, and is also used for grindinghigh precision spur and helical gears. It issuitable for the departments of the automobiles,tractors, aircraft, machine tools and toolmanufacturing industries.

MODELM1432C——UNIVERSAL CYLINDRICAL GRINDING MACHINE

The new machine features high precision,excellent rigidity and practical structure.It is made by the Beijing No.2 MachineTool Works with 40 years of experience inproducing high-precision cylindrical grindingmachines.It is already close to the standardof high precision machine tools in terms ofmachining accuracy,therefore its variousfeatures are distinctly better than previousmodels.Since being put on the market,it hasbeen well received by users. The machine is used in machineprocessing shops,tool shops and repair shopsto grind internal and external cylindricalsurfaces of cylinders and tapers.

YM7132A——GEAR GRINDING MACHINE WITH CONICAL GRINDING WHEEL

The YM7132A gear grindingmachine with a conical grindingwheel is used for grindingcylindrical spur and helical involutegears,especially for hardenedprecision gears of small andmedium sizes.

YK7232——GEAR GRINDING MACHINE WITH WORM GRINDING WHEEL

The machine is used for precisiongrinding of hardened cylindricalgears with medium module inbatches for the industries ofaircraft,automobile,machine tool,gear box and various transmissiondevices.

YK7250 Gear Grinding Machine With Worm-Grinding Wheel

The YK7250 gear grinding machine with worm grinding wheel is manufactured by the Qinchuan Machine Tool Group Co., Ltd. in Baoji City, Shaanxi Province.

Fault Diagnosis of Cylindrical Grinding Machine

Based on experiment modal analysis(EMA) and operation modal analysis(OMA), the dynamic characteristics of cylindrical grinding machine were measured and provided a basis for further failure analysis.The influences of grinding parameters on dynamic characteristics were studied by analyzing the diagnostic signals extracted from racing and grinding experiments.The significant frequency of 38 Hz related to grinding wheel spindle speed of 2 307 r/min showed that the wheel spindle system was in a state of imbalance.And wheel rotating frequency of 38.45 Hz in grinding process was close to the first natural frequency of 38 Hz, which resulted in resonance.Moreover, the main excitation at 147 Hz in grinding process together with resonance led to the deterioration of workpiece.Roundness measurement of workpiece shows good agreement with the vibration responses obtained from dynamic experiments.The fault diagnosis method was also applicable to similar machining systems.

Experimental Study of Machinability in Millgrinding of SiCp/Al Composites

An attempt was made to investigate the machinability of Si Cp/Al composites based on the experimental study using mill-grinding processing method. The experiments were carried out on a high-speed CNC machining center using integrated abrasive cutting tool. The effects of combined machining parameters, e g, cutting speed（vs）, feed rate（vf）, and depth of cut（ap）, with the same change of material removal rate（MRR） on the mill-grinding force and surface roughness（Ra） were investigated. The formation mechanism of typical machined surface defects was analyzed by SEM. The experimental results reveal that with the same change of material removal rate, lower mill-grinding force values can be gained by increasing depth of cut and feed rate simultaneously at higher cutting speed. With the same change of MRR value, lower surface roughness values can be gained by increasing the feed rate at higher cutting speed, rather than just increasing the depth of cut, or increasing the feed rate and depth of cut simultaneously. The machined surface of Si Cp/Al composites reveals typical defects which can influence surface integrity.

Study of CNC Grinding Machining Method About Isometric Polygon Profile

The formed principle and CNC grinding machining method of isometric polygonal profile are studied deeply and systematically. Equation about section curve of isometric polygon profile is set up by means of geometric principle. With the use of differential geometry theory, the curve is proved to be with geometric feature of convex curve. It is referred to as Isometric Polygonal Curve (IPC), because that is a kind of convex curve on which the distance between any parallel tangent lines is equal. Isometric Polygonal Profile (IPP) or Isometric Polygonal Cone Profile (IPCP) or Isometric Polygonal Topless Cone (IPTC) is formed with the IPC and straight line as generating curve. But the machining and measuring of the IPCP are so inconvenient that it has little value. Keeping in mind the characteristic of the IPP and IPTC, this paper puts forward the program method of CNC grinding machining. Isometric polygonal profile connection is a kind of polygonal profile connection. It has the superiority over keys (prismatic key & spline etc), and can be suit for the situations such as high rotative velocity, large torque, high precision, and small fixed room and vibration. Nowadays, some countries such as America, Russia, German and Switzerland applied CNC machining to the machining of polygon surface coupling parts, which makes their applications in machine productions such as motor engine, heavy machine increase day by day. But reports about concrete machining technology of isometric polygonal profile and programming of CNC machining program are very few. CNC grinding of the IPP and IPTC is one kind of the precision machining technology. It is of great importance to the popularization of the IPP and IPTC connection. From the forming mechanism, we can see that the machining and measuring of the IPP and IPTC are convenient, and therefore they have the value of the popularization. But the machining and measuring of the IPCP are so inconvenient that it has little value. In the programming the CNC grinding of the IPP and IPTC, it is more reasonable to calculate the coordinate of node according to the approaching method of equal error arc. According to the method of CNC grinding mentioned above to design the grinding machine, the structure is simple and of economical and practical.

Thermo-mechanical properties of bowl-shaped grinding wheel and machining error compensation for grinding indexable inserts

In order to meet the technical requirements of grinding the circumferential cutting edge of indexable inserts, thermo-mechanical properties of bowl-shaped grinding wheel in high speed grinding process and the influence of dimension variations of the grinding wheel on machining accuracy were investigated. Firstly, the variation trends of the dimension due to centrifugal force generated in different wheel speeds were studied and the effect of stress stiffening and spin softening was presented. Triangular heat flux distribution model was adopted to determine temperature distribution in grinding process. Temperature field cloud pictures were obtained by the finite element software. Then, dimension variation trends of wheel structure were acquired by considering the thermo-mechanical characteristic under combined action of centrifugal force and grinding heat at different speeds. A method of online dynamic monitoring and automatic compensation for dimension error of indexable insert was proposed. By experimental verification, the precision of the inserts satisfies the requirement of processing.

Research on CNC Turning System of Aspheric Machining Grinding Wheel

The technology of machining aspheric surface with high precision is the premise for the application of aspheric surface. The grinding machining with error compensation is a commonly used method to machine aspheric surface, which will directly influence the quality of aspheric workpiece surface. Multifunctional CNC grinding wheel truing system is a four-axis CNC truing system which can be applied to grinding wheel truing. In this system, DSP-based multi-axes motion control card is adopted as the controller, and visual C++ is used as development tool. When the design of hardware and software is completed, the system can implement truing of various grinding wheel with high precision aspheric machining such as plane grinding wheel, arc grinding one, and sphere grinding one.

RESEARCH ON PARALLEL GRINDING METHOD OF NON-AXISYMMETRIC ASPHERIC LENS

In order to resolve the problems of machining non-axisymmetric aspheric lens,which is short of flexibility in mould grinding and needs high accuracy CNC machine center in globediamond wheel grinding, a new parallel grinding method that utilizes common arc diamond wheel isput forward. Base on the approach calculation of machining locus, the advantages of parallelgrinding that machines non-axisymmetric aspheric lens by 2.5-axis CNC machine center have beenobtained. The results of grinding experiment show the new method can meet the need of grinding highaccuracy non-axisymmetric aspheric lens.

Application and Analysis of Force Control Strategies to Deburring and Grinding

This paper aims to give an insight into the development and evaluation of force controlled machining processes with a commercially available setup. We will focus on a deburring and a grinding scenario, representing the major applications in today’s robot machining. Whereas the deburring use-case implements a force dependent feed-rate control, the grinding use-case implements an orthogonal force (pressure) control. Both strategies will be evaluated and the influence of general machining and robot specific parameters will be discussed.

Nanostructured grinding wheels for ultra-precision engineering applications

Manufacturers face challenges when dealing with abrasives that lose roundness,wear excessively,and suffer from pitting of the surface of the grinding wheel that needs rectification using dressing techniques.Nanostructured abrasive grits manufactured by hybrid fusion processes and by sintering/extrusion/printing processes are found to reduce pitting quite significantly.The phenomenon of wheel collapse is increasing and cycle times developed during the grinding of aerospace alloys are much smaller compared to using conventional materials.This paper reviews the phenomenon of wheel collapse induced by pitting and takes a critical look at the production and analysis of hybrid fused and printed/sintered abrasives.A mathematical analysis is carried out of the diffusion of primary and secondary phases due to mechanical and ultrasonic agitation with the aim of producing abrasive grits with improved strength and retention.Current developments in extruded,printed,and sintered grits for use in precision grinding applications are critically reviewed.The paper concludes by explaining how such abrasives are used in practice by industrial manufacturers of high-precision products.

Design of Five-Axis Ultrasonic Assistant Compound Machine Tool

A compound machine tool was designed, which combined rotary ultrasonic assisted grinding, electrical discharge machining(EDM) and multi-axis milling. Experimental results indicated that its positioning accuracy was less than 5.6 μm and its repetitive positioning accuracy was less than 1.8 μm; the vibration amplitude of ultrasonic grinding system was uniform and stable, and the EDM system worked well and stably.A smooth surface of K9 optical glass component was achieved by the grinding method.

FEM Simulation of Single-Grit Grinding on a 2.5D Woven Composite

Single-grit grinding of a 2.5D woven composite was investigated by the finite-element method(FEM) using a unit-cell model. According to our hypotheses, the axis of the warp yarn was a sinusoidal curve and the cross section of the weft yarn was shaped like a biconvex lens. AVUMAT subroutine was used to construct the constitutive model of the 2.5D woven composite. The grinding process of the composite was analyzed using an FEM simulation with the ABAQUS/Explicit software. A validation experiment was also carried out. The simulation results showed that a grinding crack was well simulated. Furthermore, the junctions between the warp yarn and weft yarn were found to be seriously damaged and cracks were observed to extend outward along the warp fiber during grinding, in good agreement with the experimental results. In addition,the strain of weft yarns was obviously greater than that of warp yarns when the grinding direction was perpendicular to the weft yarns and parallel to the axis of the warp yarns.These results demonstrate that the mesostructure strongly influences the grinding damage inflicted on woven composites.

Study on the New Grinding Fluids of Oils on Water

To fulfill a zero-emission in the process of grinding and thoroughly eliminate the influences of the conventional grinding fluids on the eco-environment as well as save up electric energy and reduce in production costs, the new grinding fluids of botanic oils on water were developed, in which a lot of tiny water droplets attached with micro oil films were blown to the machining area by a compressing air-jet so good as to produce lubricating and cooling roles.In this study, grinding performances of the new fluids were investigated by comparison to the conventional ones such as emulsion on the plane NC grinder.