Application of the Controllable Quenching Technology to the Quenching and tempering Workpieces

In order to obtain the desired mechanical properties of quenching and tempering workpieces, as well as reduce the cracking tendency and distortion, a program of controllable quenching was established. Furthermore, a computer-aided quenching system (CAQ) was also developed. The application samples of the CAQ system showed satisfactory results.

THE INTEGRAL OF THE INVERSE FUNCTION OF φ FOR AN ANALYTICAL SOLUTION TO THE COMPRESSION OF A THIN WORKPIECE

An analytical solution of the unit pressure on a thin workpiece under compression has been obtained by using the inverse function of φ to the integral integral from 0 to x φ dx. Its result is basically the same as the prevailing numerical formula integral from 0 to x φdx=∑√1-Δx1. However, the new integral is simpler and more convenient to use.

Hot spinning of cylindrical workpieces of TA15 titanium alloy

In order to form large-diameter thin-wall cylindrical workpieces of TA15 titanium alloy,tube hot spinning experiments of the alloy were conducted on a CNC hot spinning machine.The causes of some forming defects occuring in hot spinning,such as crack,pileup,bulge and corrugation,were analyzed and the corresponding measures were put forward to avoid spinning defects,based on which a proper process scheme of hot spinning of TA15 alloy was obtained and the large-diameter and thin-walled cylindrical workpieces were formed with good quality.The results show that spinning temperature has distinct influence on forming quality of spun workpieces.The range of spinning temperature determines the spinnability of titanium alloy and the ununiformity of temperature distribution near the deformation zone leads to the formation of bulge.The reasonable heating method is that the deforming region is heated to the optimum temperature range of 600-700 ℃,the deformed region is heated continuously and a certain length of undeformed region is preheated.With the thickness-to-diameter ratio(t/D) of spun workpiece reducing to certain value(t/D<1%),surface bulge and corrugation is rather easier to come into being,which could be controlled through restraining diameter growth and employing smaller reduction rate and lower temperature in the optimum spinning temperature range.

DEVELOPMENT OF A 3-DOF MICRO-POSITIONING WORKPIECE TABLE

In order to achieve active grinding control,a novel numerical control micropositioning workpiece table with a resolution of 6 nm has been developed.The table is driven by three piezoelectric actuators mounted on the base.An elastic structure with three half-notch flexure hinges is designed to apply preload to the piezoelectric actuators.The position of flexure hinges is also elaborately designed with consideration to reduce the bending deformation of the moving part.Three capacitive sensors are used to form close loop control system.Considering the table as a damped 3-DOF mass-spring system,the models of static and dynamic stiffness and error owing to the action of external forces have been established.In order to make the table have high resolution and positioning accuracy,an error compensation algorithm is implemented by using the established models.The experimental testing has been carried out to verify the performance of the workpiece table and the established models of the micropositioning workpieee table.

Automatic Method for Synchronizing Workpiece Frames in Twin-robot Nondestructive Testing System

The workpiece frames relative to each robot base frame should be known in advance for the proper operation of twin-robot nondestructive testing system. However, when two robots are separated from the workpieces, the twin robots cannot reach the same point to complete the process of workpiece frame positioning. Thus, a new method is proposed to solve the problem of coincidence between workpiece frames. Transformation between two robot base frames is initiated by measuring the coordinate values of three non-collinear calibration points. The relationship between the workpiece frame and that of the slave robot base frame is then determined according to the known transformation of two robot base frames, as well as the relationship between the workpiece frame and that of the master robot base frame. Only one robot is required to actually measure the coordinate values of the calibration points on the workpiece. This requirement is beneficial when one of the robots cannot reach and measure the calibration points. The coordinate values of the calibration points are derived by driving the robot hand to the points and recording the values of top center point(TCP) coordinates. The translation and rotation matrices relate either the two robot base frames or the workpiece and master robot. The coordinated are solved using the measured values of the calibration points according to the Cartesian transformation principle. An optimal method is developed based on exponential mapping of Lie algebra to ensure that the rotation matrix is orthogonal. Experimental results show that this method involves fewer steps, offers significant advantages in terms of operation and time-saving. A method used to synchronize workpiece frames in twin-robot system automatically is presented.

Symmetric Workpiece Localization Algorithms: Convergence and Improvements

Symmetric workpiece localization algorithms combine alternating optimization and linearization. The iterative variables are partitioned into two groups. Then simple optimization approaches can be employed for each subset of variables, where optimization of configuration variables is simplified as a linear least-squares problem (LSP). Convergence of current symmetric localization algorithms is discussed firstly. It is shown that simply taking the solution of the LSP as start of the next iteration may result in divergence or incorrect convergence. Therefore in our enhanced algorithms, line search is performed along the solution of the LSP in order to find a better point reducing the value of objective function. We choose this point as start of the next iteration. Better convergence is verified by numerical simulation. Besides, imposing boundary constraints on the LSP proves to be another efficient way.

Milling Parameters Optimization of Al-Li Alloy Thin-Wall Workpieces Using Response Surface Methodology and Particle Swarm Optimization

To improve the milling surface quality of the Al-Li alloy thin-wall workpieces and reduce the cutting energy consumption.Experimental research on the milling processing of AA2195 Al-Li alloy thin-wall workpieces based on Response Surface Methodology was carried out.The single factor and interaction of milling parameters on surface roughness and specific cutting energy were analyzed,and the multi-objective optimization model was constructed.The Multiobjective Particle Swarm Optimization algorithm introducing the Chaos Local Search algorithm and the adaptive inertial weight was applied to determine the optimal combination of milling parameters.It was observed that surface roughness was mainly influenced by feed per tooth,and specific cutting energy was negatively correlated with feed per tooth,radial cutting depth and axial cutting depth,while cutting speed has a non-significant influence on specific cutting energy.The optimal combination of milling parameters with different priorities was obtained.The experimental results showed that the maximum relative error of measured and predicted values was 8.05%,and the model had high reliability,which ensured the low surface roughness and cutting energy consumption.It was of great guiding significance for the success of Al-Li alloy thin-wall milling with a high precision and energy efficiency.

Self-calibration and Compensation of Setting Errors for Surface Profile Measurement of a Microstructured Roll Workpiece

Microstructured roll workpieces have been widely used as functional components in the precision industries.Current researches on quality control have focused on surface profile measurement of microstructured roll workpieces,and types of measurement systems and measurement methods have been developed.However,low measurement efficiency and low measurement accuracy caused by setting errors are the common disadvantages for surface profile measurement of microstructured roll workpieces.In order to shorten the measurement time and enhance the measurement accuracy,a method for self-calibration and compensation of setting errors is proposed for surface profile measurement of microstructured roll workpieces.A measurement system is constructed for the measurement,in which a precision spindle is employed to rotate the roll workpiece and an air-bearing displacement sensor with a micro-stylus probe is employed to scan the microstructured surface of the roll workpiece.The resolution of the displacement sensor is0.14 nm and that of the rotary encoder of the spindle was 0.15.Geometrical and mathematical models are established for analyzing the influences of the setting errors of the roll workpiece and the displacement sensor with respect to the axis of the spindle,including the eccentric error of the roll workpiece,the offset error of the sensor axis and the zero point error of the sensor output.Measurement experiments are carried out on a roll workpiece on which periodic microstructures are a period of 133μm along the circumferential direction.Experimental results demonstrate the feasibility of the self-compensation method.The proposed method can be used to detect and compensate the setting errors without using any additional accurate artifact.

THE PROBLEM OF PARAMETRIC INTEGRATION TO THE SLIP LINE FIELD IN THE COMPRESSION OF THICK WORKPIECE

An integration depending on a parameter to the compression of a thick workpiece has been obtained.For the conventional prevailing numerical formulaa definite functional relationship betweenφand y is found.Therefore a parametric integration can be used to get an analytical solution.Take the slip line field for1/h=0.121 as an example,the analytical solution is basically the same as the prevailing numerical one.It is justified theoretically that for the slip line field a parametric integration is perfectly possible for a satisfactory analytical solution.

UG之WORKPIECE功能在模具型腔编程中的使用技巧

用UG软件对注塑模具的型腔加工进行编程时常遇到两个问题,一是提供的坯料是实心料,二是提供的坯料常为由线切割切去一部分的空心料。对于两种不同的坯料,在编程时,如利用UG软件的WORKPIECE功能进行相应的设置,会得到与坯料类型相适应的加工效率。

Dynamics and Control of Grinding Machine with Micropositioning Workpiece Table

为了改进表面的用机器制造的精确磨擦，用机器制造，有高效的 amicropositioning 细工品桌子被用作辅助在喂机制实现纳米水平放和动态赔偿。为了更好理解磨擦机器的特征，与微放调制了细工品桌子，磨擦系统的动态模型与形式的合成和 Lagrange 被建立“ s 方程方法。磨擦系统被划分成五个分系统。为每个分系统，概括运动学并且势能被获得。因此，磨擦系统的动态模型在形式的域被给。磨擦过程的起浪基于车轮和细工品颤动被完成。有微分追踪者的一个非线性的比例的不可分的衍生物(PID ) 控制器被开发认识到动态控制。模拟结果证明细工品的用机器制造的精确性能被利用微放细工品桌子实现动态赔偿有效地改进。试验性的测试被执行验证建议方法，并且细工品的起浪能从 0.46 下午被归结为 0.10 亩 m。

Uncalibrated Workpiece Positioning Method for Peg-in-hole Assembly Using an Industrial Robot

This paper proposes an uncalibrated workpiece positioning method for peg-in-hole assembly of a device using an industrial robot.Depth images are used to identify and locate the workpieces when a peg-in-hole assembly task is carried out by an industrial robot in a flexible production system.First,the depth image is thresholded according to the depth data of the workpiece surface so as to filter out the background interference.Second,a series of image processing and the feature recognition algorithms are executed to extract the outer contour features and locate the center point position.This image information,fed by the vision system,will drive the robot to achieve the positioning,approximately.Finally,the Hough circle detection algorithm is used to extract the features and the relevant parameters of the circular hole where the assembly would be done,on the color image,for accurate positioning.The experimental result shows that the positioning accuracy of this method is between 0.6-1.2 mm,in the used experimental system.The entire positioning process need not require complicated calibration,and the method is highly flexible.It is suitable for the automatic assembly tasks with multi-specification or in small batches,in a flexible production system.

Modifying the Traditional Analyzing Method of Cylindrical Workpieces’ Deep Drawing Process by Using a Novel Loop Material Theory Method

In this paper, the traditional empirical coefficient method and a novel loop material analytical method presented by the authors have been compared and discussed by analyzing several practical cylindrical workpieces’ deep drawing projects. Also, some conclusions about how to modify the traditional analyzing method of cylindrical workpieces’ deep drawing process could be concluded and the necessity of this modification could be proved.

A MODEL FOR SIMULATION OF FRICTION PHENOMENON BETWEEN DIES AND WORKPIECE

Based on the interaction of asperities and upperbound approach a mathematical model for simulation of friction phenomenon between dies and workpiece is proposed.Optimizing the mathematical model with respect to several variables it is found that in addition to adhering, tearing, ploughing, etc., asperities workpiece can move wave-like along the surface layer and under certain circumstances they may disappear. If the asperities wavily move along the surface layer the friction coefficient depends on the geometry of asperities. However,the bonding strength of asperities has no significant influence on friction coefficient. The depth of the plastic deformation layer is related to the geometry of asperities, too.The soundness of the prerequisite of the proposed model and some analytical results were verified by experiments.

A Predictive Modeling Based on Regression and Artificial Neural Network Analysis of Laser Transformation Hardening for Cylindrical Steel Workpieces

Laser surface hardening is a very promising hardening process for ferrous alloys where transformations occur during cooling after laser heating in the solid state. The characteristics of the hardened surface depend on the physicochemical properties of the material as well as the heating system parameters. To exploit the benefits presented by the laser hardening process, it is necessary to develop an integrated strategy to control the process parameters in order to produce desired hardened surface attributes without being forced to use the traditional and fastidious trial and error procedures. This study presents a comprehensive modelling approach for predicting the hardened surface physical and geometrical attributes. The laser surface transformation hardening of cylindrical AISI 4340 steel workpieces is modeled using the conventional regression equation method as well as artificial neural network method. The process parameters included in the study are laser power, beam scanning speed, and the workpiece rotational speed. The upper and the lower limits for each parameter are chosen considering the start of the transformation hardening and the maximum hardened zone without surface melting. The resulting models are able to predict the depths representing the maximum hardness zone, the hardness drop zone, and the overheated zone without martensite transformation. Because of its ability to model highly nonlinear problems, the ANN based model presents the best modelling results and can predict the hardness profile with good accuracy.

Temperature distribution in the tool-chip-workpiece system during the orthogonal cutting process

The temperature distribution in the tool, chip and workpiece was studied during the orthogonal cuttingprocess Under several different cutting conditions. The temperature distribution is calculated by the finite differencemethod. and the variation of the material properties with temperature was taken was taken into account The results obtained arecoincident with both previous published results and experimental measurements.

APPLICATION OF CBN WHEEL IN CONSTRAINING WORKPIECE BURNING DURING CREEP FEED GRINDING OF TITANIUM AL

ＡＰＰＬＩＣＡＴＩＯＮＯＦＣＢＮＷＨＥＥＬＩＮＣＯＮＳＴＲＡＩＮＩＮＧＷＯＲＫＰＩＥＣＥＢＵＲＮＩＮＧＤＵＲＩＮＧＣＲＥＥＰＦＥＥＤＧＲＩＮＤＩＮＧＯＦＴＩＴＡＮＩＵＭＡＬＬＯＹＸｕＸｉｐｅｎｇＨｕａｑｉａｏＵｎｉｖｅｒｓｉｔｙＸｕＨｏｎｇｊｕｎＮａ...

3D RIGID－PLASTIC FINTEELEMENT ANALYSIS OF BACKWARD SPINNING OF CYLINDRICAL WORKPIECE

３ＤＲＩＧＩＤ－ＰＬＡＳＴＩＣＦＩＮＴＥＥＬＥＭＥＮＴＡＮＡＬＹＳＩＳＯＦＢＡＣＫＷＡＲＤＳＰＩＮＮＩＮＧＯＦＣＹＬＩＮＤＲＩＣＡＬＷＯＲＫＰＩＥＣＥ３ＤＲＩＧＩＤ－ＰＬＡＳＴＩＣＦＩＮＴＥＥＬＥＭＥＮＴＡＮＡＬＹＳＩＳＯＦＢＡＣＫＷＡＲＤＳＰＩＮＮ...

基于改进SSD的工件表面缺陷检测

工件的表面缺陷不仅影响外观而且直接影响产品的质量、寿命和性能,因此对工件进行实时表面缺陷检测很有必要。针对当前SSD算法不利于小目标检测易导致误检的情况,提出了一种基于单阶段多层检测器的改进SSD自动检测方法。采用了以ResNet替换SSD中原始的VGGNet的方法,研究了小目标检测的问题;采用了对深层特征进行反卷积且将深层特征与浅层特征融合的方法,研究了语义信息不足易误检的问题。结果表明,该方法较原SSD模型在工件的表面缺陷检测上m AP值提高了约4.6%,从而认为本方法可用于工件表面缺陷的实时自动检测。

数模联动的多特征工件加工能耗预测方法研究

在实际切削加工过程中材料去除率是不断变化的,现有将其视为恒量的能耗建模方法难以实现能耗准确预测。为了提高切削过程能耗预测精度,提出了一种基于材料去除率的数模联动加工能耗预测方法。首先,基于切削过程刀具与工件的接触关系分析了切入、完全切入和切出阶段材料去除率变化规律,并对相应的加工能耗特性进行了分析;其次,提出了数据驱动的刀具切入,切出阶段加工能耗预测方法,以及模型驱动的完全切入阶段加工能耗预测方法,实现加工过程能耗准确预测;最后,利用实验案例验证了所提模型及方法的有效性,为今后研究能耗预测精度奠定了基础。