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In accordance with the vibration characteristics of ball screw feed systems, a hybrid modeling method is proposed to study its dynamic behavior. Partially, the ball screw is modeled as a continuous body, and the remaining components are considered lumped masses, allowing for a realistic description of the dynamics of the feed system. The axial, torsional, transverse, and bending vibration models of a ball screw carriage system are established via the Rayleigh-Ritz series method based on the Timoshenko beam assumption. The established model that added the Timoshenko beam assumption obtains the coupling vibration displacement between the transverse and bending vibrations of the lead screw, which is close to real situations. Numerical simulations are conducted to investigate the changes of the natural frequency and modal shapes of ball screw systems with carriage positions. Results show that the carriage position has significant influence on the amplitude and direction of axial and transverse vibrations, substantial influence on the direction of the bending vibration, and minimal influence on the amplitude and direction of torsional vibration. These results indicate that the proposed hybrid model performs well to predict the vibration characteristics of the feed system. Moreover, the carriage position and carriage load also have a remarkable effect on the frequency response of the feed system. These results, along with the modeling approach, provide an important basis for the further study of in-machining monitoring and vibration controller design.

This paper proposes a novel comprehensive modeling method for deformation errors of different types of rolling joints in machine tools to improving the analysis efficiency. This method comprehensively considers the deformation of three types of rolling joints, i.e., linear guideway, ball screw and bearing, firstly from the perspective of analytical modeling. Two comprehensive models for deformation errors of all rolling joints in two types of motion systems of machine tools are established respectively with the method. The nonlinear interfacial characteristics at rolling joints and the geometric and stiffness coupling characteristics are considered. In order to study characteristics of the synthetical deformation error of rolling joints, a synthetical error model for a five-axis machine tool is developed. Several results and optimizations of the joints are carried out. The proposed method in this paper can effectively avoid the tedious finite element modeling in the traditional analysis process and improve the efficiency.

The static stiffness of machine tools plays an important role in ensuring the performance of machine tools and improving the machining accuracy. In the design stage, stiffness matching provides a theoretical basis for determining the stiffness of each component. This study proposed a stiffness matching design method for machine tools. First, the deformation model of machine tools is established on the basis of the state space model. Through force analysis, the relationships between the deformations and stiffness of each part are determined. Second, the stiffness model of the machine tool is established by combining these relationships with the deformation model. Third, the objective function is determined by performing sensitivity analysis after obtaining the stiffness range. The stiffness matching design results are obtained through multi-objective linear programming. Lastly, the stiffness simulations, theoretical model, and experimental results are analyzed. The maximum errors among the experimental, simulation, and theoretical results (18.8 % and 19.9 %) are within the acceptable range. In conclusion, the proposed method is suitable for designing ball screw feed drive systems that requires rigidity.

We propose a comprehensive modeling approach to investigate the rigid-flexible coupling vibration of a Ball-screw-drive spindle system (BSDSS). Taking into account the rigid-flexible coupling between the ball screw and rigid components, a hybrid dynamic model for the BSDSS is established. The ball screw shaft was modeled by a flexible beam with axial, torsional, and transverse deformations, and the Ritz series expansion was used to approximate the continuous deformations. The motion equations were obtained using the Lagrange method. The analytical solution was derived and verified. According to the proposed model, the dynamic behavior of the system for various operating conditions was simulated and discussed. The numerical simulation result is useful for the controller design or tuning and the stiffness matching design of ball screw drives.

The dynamic behavior of a double-nut ball screw was investigated by means of ABAQUS 6.13© simulations based on a threedimensional model. The validity of the numerical model was demonstrated by comparing the simulation results obtained for the reaction force and torque acting on the flange of the nut with the experimental results. We found that the two sets of results deviated by no more than 5.87% given a screw rotating speed of 100 rpm. Simulations were performed to investigate the effects of the spacer width, screw rotating speed, steel ball radius and axial force on the torque acting on the nut flange. The results show that the torque increases with an increasing spacer width due to an increasing preload force. Moreover, the torque increases as the screw rotating speed increases to 700 rpm, but decreases at higher rotating speeds due to a greater centrifugal force. Ball wear prompts a reduction in the preload force and thus reduces disproportionately the torque acting on the flange following extended operation. For higher axial loads (> 100 N), the torque remains approximately constant during run-in (0.025~0.2 s). However, for lower loads, notable fluctuations in the torque occur.

Most safety inspections of large piping structures are performed by humans. However, this approach requires considerable time and money and does not guarantee the safety of the inspectors. The proposed pipe-climbing robot is designed to move on the outside of large pipe structures and perform non-destructive inspection in place of human inspectors. Required to negotiate external obstacles such as fixtures, flanges, and valves, as well as pipe components such as elbow and T-branch joints, the proposed pipe-climbing robot comprises two driving modules and an actuated connecting arm. By working together, the two driving modules overcome the various obstacle components in a pipeline network. The wheel-driven locomotion mechanisms of the system also enable it to move quickly along the pipeline. A strain gauge is attached to the climbing arm to confirm the grasping state of the robot on the pipe. The robot is designed to attach stably to a pipe, which features a very low backlash, by means of worm drive and ball screw mechanisms. Experiments show the ability of the robot to grasp stably on a pipeline and climb the pipeline at a speed of 18 cm/s.

In consideration of the bearing stiffness, the contact deformation between the ball screw and the worktable, and the contact deformation between the worktable and the guide, lateral, axial and torsional vibrations of the pre-tension screw and the vibration of the worktable were studied. A dynamic model of the ball screw drive system of machines was established by using the Lagrange equation. The model was analyzed by the mode superposition and Runge-Kutta method to calculate the transient response of the system. Effects of system’s parameters on the whirl speed of the screw, the axial vibration of the cutter’s work point, and also the stability of the system are discussed. The present work supplies a base for designing the drive system.

Pneumatic systems offer a number of advantages: typically they are fast, simple to maintain and inexpensive. However, the high compressibility of air makes control of the actuator very difficult. The purpose of this paper is to analyze the behaviors of a ball screw table powered by a vane-type air motor and then to design a robust sliding mode controller for position control. Due to the compressibility of the air and friction in the mechanism, the overall system is nonlinear. A robust sliding mode control is developed to overcome the effects of the uncertainty. Experimental results are given to validate the proposed position control strategy.

A nano positioning control is developed using the ultra-precision positioning apparatus such as actuator, sensor, guide, power transmission element with an appropriate control method. Using established procedures, a single plane X-Y stage with ultra-precision positioning is manufactured. A global stage for materialization with robust system is combined by using an AC servo motor with a ball screw and rolling guide. An ultra-precision positioning system is developed using a micro stage with an elastic hinge and piezo element. Global and micro servos for positioning with nanometer accuracy are controlled simultaneously using an incremental encoder and a laser interferometer to measure displacement. Using established procedures, an ultra-precision positioning system (100 mm stroke and ±10 nm positioning accuracy) with a single plane X-Y stage is fabricated. Its performance is evaluated through simulation using Matlab. After analyzing previous control algorithms and adapting modern control theory, a dual servo algorithm is developed for a minimum order observer to secure the stability and priority on the controller. The simulations and experiments on the ultra precision positioning and the stability of the ultra-precision positioning system with single plane X-Y stage and the priority of the control algorithm are secured by using Matlab with Simulink and ControlDesk made in dSPACE.

The machine tool joint is a very important factor in the overall machine tool dynamic analysis, and it has great effects on the machining performance of a machine tool. As a very important operation parameter, preload greatly influences the stiffness and the damping of a machine tool joint. This paper presents the effect of preload on the dynamic stiffness of the spindle nose of a horizontal machining center. By discussing types and distribution of machine tool joints, studies on the joints of ball screws, linear guides and bolts are carried out. The influence of preload on the axial stiffness of a ball screw is calculated based on Hertzian contact theory and the effect of pretightening moment on pressure of bolt joint is discussed, while the dynamic stiffness and the damping of a linear guide are identified by an optimum algorithm with the simulated and experimental results. A finite element model (FEM) of the whole machine tool structure considering the effects of different joints is created and verified against the test results, and then the influence of preloads on ball screws and linear guides is predicted. Results indicate that preloads on machine tool joints have significant effects on the dynamic stiffness of the spindle nose.

Air motors are often applied in the automation industry in areas with special requirements, such as in spark-prohibited environments, the mining industry, chemical manufacturing plants, and similar locations. The purpose of this study is to analyze the behaviors of a ball screw table powered by a vane-type air motor and to design a robust sliding mode controller for the inlet pressure. The rotational speed of the air motor is closely related to the pressure and flow rate of the compressed air. Furthermore, the compressibility of the air and the friction in the mechanism mean that the overall system is nonlinear, with fluctuating input. A robust sliding mode control is developed to overcome the effects of variations in the inlet pressure and air leakage problems. The experimental results validate the robustness of the proposed position control strategy.

To compensate for the motion errors in hydrostatic tables, a method to actively control the clearance of a bearing corresponding to the amount of error using actively controlled capillaries is introduced in this paper. The design method for an actively controlled capillary that considers the output rate of a piezo actuator and the amount of error that must be corrected is described. The basic characteristics of such a system were tested, such as the maximum controllable range of the error, micro-step response, and available dynamic bandwidth when the capillary was installed in a hydrostatic table. The tests demonstrated that the maximum controllable range was 2.4 /im, the resolution was 27 nm, and the frequency bandwidth was 5.5 Hz. Simultaneous compensation of the linear and angular motion errors using two actively controlled capillaries was also performed for a hydrostatic table driven by a ballscrew and a DC servomotor. An iterative compensation method was applied to improve the compensation characteristics. Experimental results showed that the linear and angular motion errors were improved to 0.12 µm and 0.20 arcsec, which were about 1/15th and l/6th of the initial motion errors, respectively. These results confirmed that the proposed compensation method improves the motion accuracy of hydrostatic tables very effectively.