Search

In this paper, through the construction simulation of the installation and jacking of a large steel grid project, ANSYS software is used to select the corresponding finite element module, and by analyzing the construction models of different modes and different load conditions, the analysis results and structural models are displayed. The 12 supporting hydraulic jacks can meet the overall steel structure hoisting requirements on site. At the same time, the calculation model takes into account the deformation of the overall grid during the unloading process. After testing, the maximum displacement is 7mm, which meets the requirements of national regulations. This method better supports the construction guidance, and also achieved good benefits during the on-site implementation process. The installation plan and jacking technology are worthy of reference.

In cam grinding process, the grinding force changes with the change of cam contour, and its change leads to create the error of X-C linkage servo-tracking position, all of the factors reduce the cam the contour accuracy. To improve the accuracy of the cam profile, and research the effect of X-C axis servo tracking, the key vector of grinding force to the position is proposed, in which the factors have been considered including the grinding depth, curvature change, cam width, length and other effects. According to the mechanical analysis of cam and grinding wheel, a cam grinding XC-axis grinding force model is established. With the flat-bottomed follower cam as an example, the grinding force of X axis and C axis is calculated. The cam grinding experiment was conducted in the grinding machine, the tangential grinding force and normal grinding force were obtained and the model was verified. The grinding force mathematical model of X-C linkage provides the theoretical basis for the servo tracking position of X-C linkage grinding.

An off-line decoupling compensation method for Noncircular Grinding contour error is presented in this paper. The contribution of the axis deviation to the non-circular contour error was analyzed by the projection of the axis deviation to the normal direction, the decoupling method of X_C axis independent compensation is given. The off-line compensation experiment shows that the contour error is suppressed and the decoupling method is effective.

In order to obtain higher cam quality, the research on the cam contour error is studied. The cam is machined in the way of X-C biaxial linkage motions. The linear motor drives the grinding wheel mechanism to get the motion of X axis, and the motion of C axis is the rotating of cam driven by the torque motor. Because of the servo-system-lag of the two axes, the cam contour error is formed in the X-C biaxial linkage motions. Moreover, the following position error of X axis and C axis is not same as the cam contour error. The relationship between axis following position error and cam contour error is studied. The mathematical model of cam contour error is constructed, the relationship between the cam contour error and the following position error are obtained. At last, the conclusion which the cam contour error can be controlled is made, although the following position error exists at the same time. To design the contour error controller for higher quality cam is based on the above conclusion.

The structure of a precision high speed spindle system is described. The shaft and bearing finite element models of the spindle system are constructed by using the Timoshenko beam element and the spring-damper unit. The static mechanical properties of spindle system and modal analysis are studied with different spring element arrangement forms. The results showed that the rotary speed designed was far lower than the critical rotary speed which matched with the low-order modal natural frequency of the spindle,so resonance vibration could be effectively avoided.

The research on the dynamics modeling in theory and experiment for the rolling bearing-motorized spindle system including bearing modeling and spindle-bearing system modeling is reviewed. The main factors influencing the motorized spindle system dynamics are analyzed combined with the pratical engineering, which include thermal characteristics, high-speed effects and electromechanical coupling. The methods for dynamics modeling including the transfer matrix method and finite element method are related. Finally, the research directions on the dynamics of rolling-bearing motorized spindle system are forecasted.

Composite grinding machine for non-circular shaft parts, on the workpiece servo spindle high requirements.In order to overcome the vector control coordinate calculation of complex, slow response speed and other defects, this paper adopts the direct torque control scheme of asynchronous motor spindle servo control research.Using the Matlab/Simulink module library provides the basic module, built asynchronous electric spindle direct torque control system model.Coordinate transformation process were established, flux adjust step, flux observation, link and loop PID position control module, and the use of subsystem package technology package.The current loop, speed loop, ring in position and torque simulation test, the results show that, the method of direct torque control of asynchronous motor spindle control drive control system can obtain good static and dynamic response characteristics and the closed-loop response performance.

In order to improve accuracy of measuring motor speed in precision motor control systems, a method of precise measurement of speed with CPLD is proposed, which measures the truncated parts of the measured pulse on the basis of measuring raster count pulse within the equal period, and takes them as compensation, thus improving accuracy of measuring the raster pulse. In this paper, a speed measuring formula is given. Measuring system is provided with parallel and serial communication interfaces for output of measurement results.

With the development of auto industry, the cam quality requirements higher and higher. In order to illustrate the effect of servo lag upon cam Contour error, X-C servo axis Trajectory coordinates have been acquired in real-time with dual-channel mode during cam grinding. By comparing the Trajectory coordinates detected and the interpolation contour, the errors caused by servo feed lags were verified, and the mechanism that how axis feed acceleration impact on cam Contour errors was proposed. Based on data acquisition and product test, the error compensation method based on servo lag is proved reasonable.

The double channel function of Siemens 840d numerical control system collected the input data needed by BP neural network model. Combined with detection lift error in actual process of machining CAM, the detecting lift error is predicted with using of BP neural network model designed by the neural network toolbox and the train of neural network. The test results of this method are proved to achieve the predicted effect, which means that can be used in the CAM processing lift error prediction.

With the development of auto industry and aviation industry,the cam quality requirements higher and higher. The NURBS curve has excellent natures that can smooth the cam grinding path and improve its processing quality. Combined with existing CAD software and CNC systems, respectively, from reverse and forward two aspects of NURBS curve to illustrate the non-uniform B-spline principle and given the relevant formulas. Choosing X-C coordinates points of the cam grinding as the research object, adopt reverse and forward NURBS curve interpolation to fit the cam grinding path. Analysed the fitting error caused by line segment fit NURBS curve and cam lift error caused by NURBS interpolation. Summarized the advantages and disadvantages of two ways Nurbs interpolation discussed the method to improve NURBS interpolation for cam grinding.

With constant development of machine tools toward the direction of high speed, high precision, high efficiency and high compound rapidly. The performance of high-speed machine tools is affected by the dynamic characteristic of machine tools in the very great degree. More and more attention is played to them and higher and higher demands are proposed. Finite element method is a kind of fast and efficient auxiliary tools in modern engineering analysis and design. Three-dimensional finite element model of spindle box is established in this paper based on large finite element analysis software ANSYS. Through modal analysis, the first five order natural frequency, vibration mode and various order vibrating modal characteristics are obtained. These results are verified by using the method of experimental modal. Harmonic response analysis is carried after doing modal analysis on spindle box. Response and stress under different frequency are obtained. Continuous dynamic characteristics are forecasted.

Used fixed equal step cubic spline interpolation in non-circular machining, the influence of acceleration may be too strong to cause burns and vibration. To suppress the acceleration influence of feed axis, take cam grinding as an illustration, first derived acceleration and its change from the cubic spline function, then adopting the method of off-line fuzzy model logical reasoning combined with five points of three power smooth, obtained the modified variable interpolation time steps. The experiment results that the feed axis acceleration stability used fuzzy step cubic spline interpolations is much better than equal step spline in cam grinding under the same processing efficiency.

With the production system of modern manufactures complexity increasing, it is very difficult to establish a practical model to satisfy the current trend by means of traditional methods and theories of modeling. According to IDEF0 modeling method, this paper presents a functional model of the production line object model framework. Based on this, an object-oriented abstraction mechanism is considered to solve the camshaft production line complexity practical situation and an object-oriented Petri nets (OPNs) modeling is proposed. Simulation models are established by using Witness 2008 simulation software based on camshaft production line to analyze the layout and bottleneck of production line, to check the design programs, and to optimize configuration and layout of the production line furthermore. The manufacturing capacity of the line is also discussed in this paper. Finally the corresponding solutions to avoid the existing bottleneck of the line are also discussed in detail.

As the key parts of cars, camshafts influences a lot on the quality and durability of cars. Their processing is complicated, time and place consuming and the quality is difficult to guarantee. The turning-grinding composite machine tool (TGCM) for camshafts is studied on basis of ‘process integration with one setup’ theory in this paper. It presents the structure of the turning-grinding composite machine tool by the analysis of the function of TGCM. The revolving working table is used to transfer the turning and grinding function. It also discusses the constant grinding removal rate mathematic model of the cam contour machining. The opened-CNC system for this machine tool is developed by using the VC++6.0 based on PC and UMAC controller. The constant grinding rate model of the cam contour is verified by the experiment results.