Benefits for your Students • Access to ASME student competitions/E-Fests, scholarships, internships and more • Exposure to the engineering community and real world situations, in and out of the classroom • Technical information & interactive tools to help with coursework and research • Mentoring by an experienced professional • Networking in person & online, locally & worldwide • Valuable relationships that can last a lifetime • Easy application process with no additional costs Benefits for your School • Supplements your curriculum and coursework • Provides targeted and relevant experiences beyond the classroom • Keeps you connected to the latest trends and industry developments • Offers exposure to international issues & perspectives • Exemplifies your exceptional commitment to your program and your students • Easy program administration, and the convenience of making a single payment

American Society of Mechanical Engineers (ASME)

Machine tools play a pivotal role in the manufacturing world since their performance significantly affects the product quality and production efficiency. In the era of Industry 4.0, machine tools a...

Digitalisation and servitisation of machine tools in the era of Industry 4.0: a review

How to make a controller robust and stable to reject the disturbance of uncertainty is an inevitable challenge. Aiming at addressing the lateral control problem for an autonomous road sweeper, a heading-error-based first order linear active disturbance rejective controller (HFO-LADRC) is proposed in this paper. To eliminate the lateral error and the heading error at the same time, a new model, called the heading-error-based model, is proposed for lateral motion, and the Lyapunov function was employed to explore the convergence ability of the heading error and lateral error. Since the heading-error-based model is first order, the ADRC is designed as first order and linear, and each module of the HFO-LADRC has been devised in detail. To ensure solution accuracy, the fourth order Runge-Kutta method was adopted as the differential system solver, and a typical ring scenario and a double lane-changing scenario were designed referencing the standard. Considering the obvious influence, wheelbase uncertainty, steering ratio uncertainty and Gaussian white noise disturbance were taken into account for the tests. The results illustrate that, in the case of both wheelbase uncertainty and steer ratio uncertainty, the HFO-LADRC has strong robustness and stability compared with a typical pure pursuit controller and classical SO-LADRC.

HFO-LADRC Lateral Motion Controller for Autonomous Road Sweeper.

The cylindricity and coaxiality of the stepped shaft are important parameters reflecting the vibration characteristics of the rotating machines system. In order to evaluate the cylindricity and coaxiality of the stepped shaft accurately, the paper proposes a cylindrical profile measurement model, which takes into account five kinds of systematic errors and analyzes the combined effects of five systematic errors on cylindrical profile measurement results. Based on the proposed measurement model, the distribution of sample angle deviation caused by five systematic errors is studied. A non-uniform spline filter is designed, and the effect of uniform and non-uniform spline filter methods on the cylindricity and coaxiality of stepped shaft are analyzed. In order to verify the effectiveness of the cylindrical profile measurement model with five systematic errors and the spline filter method proposed in the paper, a rotary measuring instrument with high precision is built. The experimental results show that compared with the traditional measurement method, the measurement accuracy of cylindricity and coaxiality can be improved by 11.43 μm and 8.99 μm for stepped shaft with large radius on the proposed method, respectively. The proposed method is suitable for small probe radius and large eccentricity error, probe offset error, workpiece tilt error, and guide rail tilt error, especially for stepped shaft with large radius, such as aerospace engine, gas turbine, and machine tools.

A cylindrical profile measurement method for cylindricity and coaxiality of stepped shaft

During five-axis CNC machining, the dynamic tracking error caused by imperfect servo dynamic performance is becoming the major factor affecting the accuracy during high-speed and high-precision manufacturing. The double ballbar (DBB) test is one of the commonly used dynamic performance tests, but existing DBB test methods do not have satisfactory test capability for the requirement of complex freeform surface machining. In this paper, on the basis of summarized of dynamic tracking error’s mechanism and characteristics, an improved dynamic performance test based on DBB, which is named the circle-8 test, is proposed. In this test, a provenly efficient RTCP test trajectory is used to rebuild the DBB test process, which includes complex movements of all the five motion axes. To exhibit the improvement of the circle-8 test, this test and the BK3 test of ISO standard, which is considered as a comparison, are conducted in a five-axis machine tool with a tilting rotary table. According to the simulation and experiment results, for common dynamic inaccuracy situations, the circle-8 test always has better sensitivity of dynamic performance test than BK3 test. The above-improved dynamic performance test can be applied to provide effective data for the research of modeling and error reduction of five-axis machine tools.

Dynamic performance test under complicated motion states for five-axis machine tools based on double ballbar

The evaluation of contouring error is important for multi-axis CNC machines because the tolerance specifications of manufactured parts are directly affected by contouring error. One of the fundamental quality inspections to verify that a manufactured part meets the expected tolerance is via form error evaluations. However, the existing estimation methods of contouring error are based on the position tolerance requirements. To meet the form tolerance requirements for the parts, this paper focuses on developing a high-accuracy estimation method of contouring error that is not related to a datum (ND-contouring error). In the proposed estimation method, at first, the minimum zone tolerance (MZT) method is used to transform the ideal tool tip path to match the actual one. Subsequently, by comparing the position and orientation between the actual point and the nearest point on the transformed ideal tool path, the ND-contouring error and orientation contouring error of the tool can be estimated, respectively. In addition, the difference between the proposed estimation method and previous evaluation methods is comparatively analyzed. Finally, simulations and experiments are conducted by applying the S-shaped and B-shaped machining trajectories, respectively, and the results all verify the estimation accuracy of the ND-contouring error estimation method. By adoption of compensation based on the ND-contouring error estimation, the contouring error could be significantly reduced, which will improve the quality of parts.

A new contouring error estimation for the high form accuracy of a multi-axis CNC machine tool

During five-axis CNC machining, the dynamic performance is the core factor to decide the efficiency and accuracy during high-speed and high-precision manufacturing. As a common method to detect dynamic performance of five-axis machine tools, measurement by using RTCP (Rotation Tool Centre Point) is always known as a better way than others with the advantages of high detection accuracy, variable detection trajectory and little interference. The key to effective detecting with RTCP function is the suitable trajectory, and in previous research, the 8-shape trajectory is proposed as an effective RTCP trajectory. In this paper, the 8-shape trajectory is adapted to machine tools with different rotary axes. The effects of the servo position gains, initial setup position, feed rate and on five-axis machine are shown in the simulation model, and the geometry and symmetry of the tool center point error trajectories are summarized to provide a guide to the improvement of dynamic performance.

RTCP Detection for Five-Axis CNC Machine Tool Dynamic Performance Based on 8-shape Trajectory

Nowadays the five-axis machine tool is one of the most important foundations of manufacturing industry. To guarantee the accuracy of the complex surface machining, multi-axis linkage performance detection and compensation of five-axis machine tools is necessary. RTCP (Rotation Tool Center Point) is one of the basic essential functions for the five-axis machine tools, which can keep the tool center with the machining trajectory when five axes move synchronously. On the basis of RTCP function, a way to detect multi-axes linkage performance of five-axis machine tools is briefly introduced, and linkage error model is built in accordance with the topological structure of machine tool. Based on the feature of the linkage errors of the five-axis machine tool, the error tracing and compensation method is proposed. Some simulations and experiments that verify the error tracing method could locate the linkage error category are established. Therefore, a new attempt to detect and compensate the linkage error of the five-axis machine tool is provided in this paper.

An Attempt of Error Tracing and Compensation Method of the Linkage Error of Five-Axis CNC Machine Tool

During five-axis CNC machining, the dynamic tracking error of the five-axis machine tool caused by imperfect servo dynamic performance is the major factor affecting the accuracy during high-speed a...

https://journals.sagepub.com/doi/pdf/10.1177/1687814020967573

Qicheng Ding

Papers

A new contouring error estimation for the high form accuracy of a multi-axis CNC machine tool

Dynamic performance test under complicated motion states for five-axis machine tools based on double ballbar

RTCP Detection for Five-Axis CNC Machine Tool Dynamic Performance Based on 8-shape Trajectory

An Attempt of Error Tracing and Compensation Method of the Linkage Error of Five-Axis CNC Machine Tool

An attempt to relate dynamic tracking error to occurring situation based on additional rectilinear motion for five-axis machine tools: