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A novel principle of cup wheel grinding of rotating concave quadric surface was proposed. The mathematical model of machining process was established to prove the feasibility of precision grinding of rotating concave paraboloid based on the introduced principle. The conditions of non-interference grinding of concave paraboloid were mathematically derived. The processing range and its influence factors were discussed. The trajectory equation of abrasive particle was concluded. Finally, the math expressions of numerical controlled parameters was put forward in the process of grinding of the concave paraboloid.

High hardness surface coating sphere components are widely used in metal sealing ball valves. The spherical surface grinding texture influences the valve’s tribological performances such as friction, lubrication and wear of interacting surfaces. It can be used to develop the index of grinding parameter optimization. In this paper, based on the discussion of sphere generating grinding methods, the surface grinding texture is quantitatively analyzed. The space trajectory of abrasive particles during sphere grinding is studied. The trajectory mathematical models are built based on two kinds of sphere grinding manners and are verified by comparing the theoretical results against experimental measurements. The influence of grinding parameters on the texture is analyzed. Texture density are defined to quantitatively describe the surface texture. The relationship between grinding texture and ball valve performance is finally discussed. The conclusions can help to optimize the spherical surface grinding process.

In this paper, the birch flour was the raw material with its particle size less than 100μm and the polyester hot-melt adhesive was used as binder with its particle size less than 60μm. The birch flour was dried using high speed mixer with heating function. The birch flour/polyester composite were prepared using the physical mixing method. The surface of the specimen and fracture surface of specimen were analyzed through the micrographs of scanning electron microscopy. In order to study the characteristics of laser sintering, the preheating temperature of the powder bed of laser sintering machine and the processing parameters of the birch flour/polyester composite were determined using single layer sintering method and empirical method. The tensile, flexural and impact specimens were built in the two scanning laser ways of subarea scan and progressive scan. The testing results show that the mechanical properties using subarea scan method are superior to those of progressive scan method and the mechanical properties of the specimens increase as the laser scan speed decreases. The best mechanical properties of SLS specimens of brich flour/polyester composite powder were obtained with the following parameters: the laser power was 11W, layer scan speed was 1800mm/s; layer thickness was 0.1mm; laser scan spacing was 0.1mm and the average tensile, flexural and impact strength of specimens were 1.35MPa, 3.69Mpa and 0.73KJ/m2 respectively.

Bamboo flour is a kind of a cheap reproducible natural plant powder. The polyamide hot melt adhesive (polyamide) is good bamboo adhesives. The bamboo flour/polyamide blend is prepared through mechanical mixing method. The powder bed preheating temperature of the laser sintering processing and the processing parameters of bamboo flour/polyamide blend are determined through the differential scanning calorimetry method (DSC method) and single layer sintering experiment. The mechanical testing parts are successfully fabricated by selective laser sintering using the bamboo flour/polyamide blend of 25/75 (wt/wt). In this series of experiments, the average tensile strength, flexural strength and impact strength of 5.9Mpa、11.5Mpa and 4.5KJ/m2 are obtained when the laser power is 11W, scan spacing is 0.1mm, the thickness of a layer is 0.1mm and scanning speed is 2000mm/s. The tensile strength and flexural strength of the SLS specimens are improved through wax infiltrating process, while the average impact strength of the wax-infiltrated specimens decreases compared with the SLS specimens processed under the same set of parameters. Bamboo flour/polyamide composite powder is new laser sintering with good forming property and low cost.

In order to study the kinematic characteristics of the tree transplanter and the hydraulic cylinder, this paper established the model of the tree transplanter with the Cero2.0 software and analyzed kinematic characteristics of the hydraulic cylinder and the tree spade when the tree spade was driven by the hydraulic cylinder with the analytical method. The dynamic simulation curves of the angular velocity and the angular acceleration of the hydraulic cylinder can be obtained with the Matlab software. Then the appropriate format model file was imported into Adams software, and the angular velocity and the angular acceleration of the hydraulic cylinder were analyzed and simulated in Adams. The obtained curves in Adams software were compared with the curves obtained with the Matlab using the analytical method. The result revealed that the trends of the two ways simulation curves were consistent. The comparison showed the analytical method of kinematic characteristics of the tree transplanter and hydraulic cylinder was correct.

Laser rapid forming is a kind of new developed technology combining laser surface modification and rapid prototyping technology. It provides a powerful tool for the manufacturing and repairing of metal components. Laser rapid forming repairing experiments of 45 and 2Cr12 steel have been carried out with 316L stainless steel powder. Microstructure and properties of the repaired components are analyzed and tested with optical microscopy (OM), scanning electron microscopy (SEM) and electronic tensile experimental machine etc. Repaired components of different materials have been metallurgically bonded with the deposited layers, with fine microstructure, better mechanical properties and free of defects.

This paper presented a new technique, which was the online wear evaluation of wheel in grinding WC-Co coating by using wavelet packet decomposition. Based on the measurement method, theory of online wear evaluation of wheel was introduced. The selection principle of characteristic signals was brought up, and the grinding acceleration signal was the best choice among many characteristic signals. The time domain signal analysis method of wavelet packet decomposition was analyzed. Lastly, experiments on the wear of wheel were performed, and experimental results showed the validity of the method.

To investigate the effect of micro-topography on the wear properties of the cold roller, rough surface was characterized with fractal geometry, and the profile of laser-textured surface was measured based on the analysis of surface profile self-similarity, feasibility of fractal characterization of the surface was studied with power law method. Results show that Isotropic surfaces tend to be fractal and surfaces processed under definite technological conditions can be characterized with fractal geometry. On this basis, effects of surface fractal parameters on the wear rate of the roller were analyzed with fractal geometry model for wear prediction. Condition of achieving optimal fractal dimension was presented and the expression of the optimal fractal dimension was derived for the minimum normalized wear rate. It shows that normalized wear rate is mainly determined by fractal dimension besides the material properties and an optimal fractal dimension existed for the engineering surface is affected by the plastic index, normalized true contact area and scale coefficient. The results will provide bases for the studies of friction and lubrication of the textured steel sheet and guidance for the actual processing.

The surface texture of sheet steel plays an important role for automotive applications. To achieve appropriate surface topographies and press-forming behaviour, a new laser coating texturing (LCT) technique aimed at texturing steel work-rolls was proposed. The laser texturing process was realized by applying laser pulses at very high repetition rates to produce innumerable micro-craters with the required shape profile on the surface of the rolls. Moreover, the surface alloying of the dimples was carried out on the substrates of bearing steel GCr15. The submicron WC-Co alloy metal powder was melted into the micro-craters by high laser energy. The effects of processing parameters on the properties of the laser textured samples were investigated. The dimpled surfaces were examined by a 3-dimensional surface profilometer. Microstructures of the coating layers were assessed by optical and scanning electron microscopy. The experimental investigations show that the laser-dimpled hard-coated surfaces exhibit compatible metallurgical interfaces with the substrates. The laser coating textured roll is demonstrated to have excellent abrasion resistance and a much longer service life. The abrasive wear resistance was 5 times higher than that of the substrates. The average surface microhardness values were as high as 700HV.

The processing parameters of laser texturing are linked with the wear property of roller surface based on the relationship between the fractal parameters and surface roughness. The influence of laser power density, scanning speed and pulse width on the roughness is analyzed though experiments. The effect of fractal parameters on the wear rate of the roller is analyzed with fractal geometry model for wear prediction. Condition of achieving engineering surface with optimal fractal dimension is presented and the expression of the optimal fractal dimension is derived. It shows that the roughness of laser textured surface and normalized wear rate are mainly determined by laser power density and fractal dimension, respectively. Moreover, to get the textured surface with smallest nominal wear rate, processing parameters of laser texturing, especially the laser power density, should be controlled properly besides the material properties of the roller. The result will provide guidance for the processing.

Spindle thermal deformation is the main error source of many precision profile grinders. In this paper, the relationship between spindle temperature and either radial or axial thermal deformation is studied based on experiments. The placement and amount of temperature sensors are optimized. Then a kind of thermal error modeling method based on support vector machine is presented and applied in the modeling of thermal error of profile grinding. The result shows the model is robust and the on-line accurate prediction of grinding thermal error is realized based on monitoring of temperature rise of spindle. Finally, the error compensation strategy is discussed for further application of thermal error modeling.

This paper deals with an application to automatic compensation of grinding wheel wear by an image processing based real-time measurement method in dry curve grinding. An online image measurement system was schemed out and its principle was introduced in detail. Real time image of workpiece and grinding wheel is grabbed by CCD camera during grinding process. For the purpose of increasing the measurement precision, a new sub-pixel level accuracy edge detection approach combining Zernike moments operator with Sobel operator is proposed for locating the edge of the machined workpiece, which has advantages of fast processing speed and high edge locating accuracy. The wear amount of the grinding wheel is calculated by the image processing software, and is compensated automatically by NC controller. Finally, this method is applied to a new type CNC curve grinding machine MD9040. The experimental results show that the measurement and compensation method proposed in this paper is effective, and the contour error of the workpiece with real-time compensation is less than the feeding resolution for a compensation of 2μm.

Image analysis was used to evaluate the curve grinding process. The measurement system organization and its principle of operation were introduced. Some key technologies that influence the system precision were also studied in details. Real-time image of work piece and wheel grinding can be gathered while using CCD camera. For image de-noising, a kind of wavelet threshold function was presented to calculate the new wavelet coefficients. Local threshold algorithm was used to compute different scale threshold, another threshold is suggested when MSE is minimum. Image signals are reconstructed through invert discrete wavelet transformation with the new wavelet coefficients. For the purpose of increasing the measurement precision, a closed mathematical model of sub-pixel edge detection operator was founded according to the gray moment operator’s invariant characteristics and Tabatabai’s first three sample gray moments. An application of system validity and the comparison results of work piece were also given. From experiments it can be said that the proposed method in this paper is effective, and its detection precision and results are reasonable.

This research is to investigate the dynamic characteristics of the grinding process. A kind of robust grinding wheel reciprocating arrangement is schemed out, which realizes the precise point-grinding machining. The grinding wheel reciprocating movement is driven by a linear motor to replace the traditional crank or hydraulic pressure drive device. Based on the time series method, the modal experimental analysis technique has been adopted in this paper. By acquiring acceleration signals of multiple positions of the grinding wheel slide, the dynamic characteristics are analyzed and the modal parameters of the structure are identified by virtual analysis program. The boundary condition of the finite element model is adjusted for optimizing its dynamic characteristic. The equivalent substructure is created and modified in order to improve the surface grinding quality. This study has got satisfying results. The grinding wheel movement realizes the self-regulation control and reduces the surface waviness and roughness during high speed point-grinding operation.

Experimental study on the laser direct fabrication (LDF) of stainless steel powder is carried out. Microstructure and properties of the deposited components are analyzed and tested with optical microscopy (OM), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) etc. Cracking generation mechanisms of this material are investigated, corresponding cracking control strategies have been proposed. Finally, fully dense stainless steel components free of defects and with perfect comprehensive mechanical properties have been produced.

Both diamond wheel and CBN wheel belong to super-abrasive wheels. Diamond wheels have superior grinding performance. The metal-bonded diamond wheel can grind hard brittle material component with a complicated shape precisely and efficiently. Because dielectric liquid is forbidden on numerical control optical profile grinder, the information on profile truing and dressing diamond wheel mounted on numerical control optical profile grinder is not readily available. In this paper, a novel truing and dressing method, namely dry electrical discharge (dry-ECD) assisted truing and dressing, is proposed. The experiments of dry-ECD assisted profile truing and dressing of diamond wheel are done by the authors. The experimental results show that both geometrical accuracy and surface topography of diamond wheel have attained technical requirement under appropriate truing and dressing conditions. There is not much difference in grinding abilities of new diamond wheel and dry-ECD assisted truing and dressing diamond wheel.

Rolling cutter curve-edge is a complex spatial curve. This paper states the present method of tool radius compensation for grinding it by 4-axis gang control grinding center, analyzes the existence of processing error due to this method, and proves the error can not be neglected. To avoid the error, a new method of tool radius compensation based on vector decoupling is raised. From a comparative experiment, it shows that the new method can promote processing precision and enlarge work-life of rolling cutter evidently.

Chatter marks that limit ground surface finish have been observed in accurate grinding by using optical curve grinder. To reveal the mechanism of chatter marks, the relationships between grinding parameters and chatter marks are experimentally studied. The profile of the ground surface is analyzed through microscope as well as FFT method. It is found the dynamic characteristics of grinder and the vibration test are efficient tools for this study. Modeling of grinding chatter marks is proved effective for the result of simulation showing consistent with that of experiments. The results of study point out the way to eliminate chatter marks and establish the basis for detection and prediction of the marks.

A CCD on-line image measurement system for curve grinding was schemed out according to the working process. Real-time images of work piece and wheel grinding can be gathered while using synchronal control and outer trigger technology. For the purpose of increasing the measurement precision, we presented a new method for locating edges in digital images to sub-pixel values based on local interpolation and spline fitting. An application of its validity and the comparison results of grinding wheel wear are also given. Experiments show that the proposed method in this paper is effective, and its detection precision and results are reasonable.