Thermal Deformation Of Ball Screw Research Articles

Optimization of nano coating to reduce the thermal deformation of ball screws

Abstract To reduce the thermal deformation of ball screws, the process of nano coating preparation for coating on ball screws to reduce temperature rise and thereby thermal deformation was discussed in this article. Simultaneously, the cooling mechanism was presented. The thermal channels and the relatively even distribution of graphene in the nano coating were observed in scanning electron microscopic images. In terms of the preparation of nano coating, optimization design was carried out to obtain the optimized material ratio and nozzle flow through orthogonal experiment. The influence of design parameters of nano coating on reducing thermal deformation was also discussed. The experimental results show that the maximum temperature rise, thermal deformation, and time to reach thermal balance decreased by 12.5, 69.1, and 46.3%, respectively. The effectiveness of nano coating in reducing thermal deformation was validated experimentally.

Thermally stimulated artificial muscles: Bio-inspired approach to reduce thermal deformation of ball screws based on inner-embedded CFRP

Abstract Ball screws are the indispensable machine tool components and, as such, influence the positional accuracy of machine tools. The accuracy stability of machine tools is affected by thermal deformation of ball screws resulting from the increase in temperature. Inspired by the distinctive artificial muscle heat behavior, a bio-inspired ball screw was proposed. The proposed ball screw was based on the inner-embedded carbon fiber-reinforced plastic (CFRP), which restrains the axial expansion through the thermal contraction of CFRP. Additionally, a thermal conductor was mounted between the screw shaft and CFRP to improve the thermal conduction condition. Furthermore, both the simulation analysis and comparative experiments were carried out to compare the bio-inspired ball screw with the standard one. Two working conditions were considered to evaluate the effectiveness of the novel design, primarily in terms of reducing thermal deformation. Both results show that the proposed approach is effective and can be applied to reduce the thermal deformation of ball screws.

Bio-inspired graphene-coated ball screws: Novel approach to reduce the thermal deformation of ball screws

To reduce the thermal deformation of ball screws, a novel approach inspired by silver ants is proposed. The Saharan silver ant maintains low body temperatures in one of the hottest terrestrial environments by radiating heat to the surrounding environment. Inspired by this, bio-inspired graphene-coated ball screws, which can enhance heat dissipation due to radiative heat dissipation of graphene coating, are designed to reduce the temperature and thermal deformation further. Finite element analysis is conducted to validate the excellent performance of the proposed bionic design in reducing thermal deformation. In order to verify the advantage of this method, comparative experiments between graphene-coated ball screws and the ordinary one are carried out on a self-designed test bed as well. The result shows that the bio-inspired design obviously reduced the temperature rise, thermal deformation, and temperature balance time. This bio-inspired approach will provide a new idea to solve the thermal issue of machine tools.

Further study on thermal deformation reduction for CFRP-based improved ball screws

To determine the thermal deformation of ball screw in actual working condition, a novel method for determining thermal deformation of ball screws in complicated working condition is proposed based on G-code and finite-element (FE) method. In the complicated working condition, it is difficult to obtain and import the nut movement into FE model due to the complex nut movement. In this research, the nut movement is directly determined from G-code by MATLAB code programming. The nut location is recorded with time in a file. The thermal parameters can be determined according to the nut speed with time as well. In the implicit FE analysis, the nut location is read from the input file instead of nut location calculation before every time step. And then, the effect of factors, such as working condition and materials, on thermal deformation reduction of ball screw is studied. The thermal deformation reduction of ball screws under different rotational speed, actual working condition, and different axial elastic modulus of composites is discussed, which can provide the guidelines to evaluate the thermal deformation reduction and design the composite in improved ball screws.

Adaptive Method to Reduce Thermal Deformation of Ball Screws Based on Carbon Fiber Reinforced Plastics.

In high-speed precision machining, thermal deformation caused by temperature rise affects the accuracy stability of the machine tool to a significant extent. In order to reduce the thermal deformation of ball screws and improve the accuracy, a new adaptive method based on carbon fiber reinforced plastics (CFRP) was proposed in this study and the thermal deformation of ball screws was determined. By using the sequential coupling method, the thermal–structural coupling analysis of a ball screw was conducted based on the finite element method (FEM). The analysis results were verified through a comparison with the experimental results. Based on the verification, an FE model of the improved ball screw was established to study its thermal characteristics. The key design parameters of the improved ball screw were optimized based on the Kriging model and genetic algorithm (GA). The thermal reduction effect of the improved ball screw was validated through the experimental results. The results indicate that the adaptive method proposed in this research is effective in reducing the thermal deformation of ball screws.

Modelling and compensation of thermal deformation for machine tool based on the real-time data of the CNC system

As one of the main issue affecting the precision and stability of the machine tool, thermal deformation is determined by the environmental temperature as well as the heat generated in the working process of machine tool. Currently, research work on the modelling of thermal deformation mostly rely on the data retrieved from temperature sensors embedded or amount on the machine tool, where the thermal deformation is modelled as function of temperature field in the machine tool. Thermal deformation thus modelled is normally impractical in the thermal compensation process because of the high cost and low stability it may incur when a set of temperature sensors are utilized. In this paper, a novel approach for modelling and predicting the thermal deformation of ball screw is proposed. Instead of relying on the data from temperature sensors, the real-time data of the CNC system, e.g., current and velocity of driving motor, and displacement of axis, is utilized directly to derive the thermal deformation model. With such data, a model is firstly built with considering the heat generated from friction motion as well as the heat dissipation with the machining environment; the parameters of the proposed model were then identified by a multiple linear regression method. Based on the proposed model, the thermal deformation of ball screw can be precisely estimated in both the warming up and cooling down state of the machine tool, as validated by experiments on a ball screw of a small size machine tool.

고속 고정밀 볼 스크류 구동에 따른 강제 냉각방식의 효과에 관한 연구

Ball screw system is widely used as a precision mechanical linear actuator that translates rotational motion to linear motion for its high efficiency, great stiffness and long life. Recently, according to the requirements of high accuracy and stiffness, the pre-load on the ball screw which means of remove the backlash in the ball screw is usually used. Because of the preload which means the frictional resistance between the screw and nut, becomes a dominating heat source and it generates thermal deformation of ball screw which is the reason for low accuracy of the positioning decision. There are several methods to solve the problem that includes temperature control, thermal stable design and error compensation. In the past years, researchers focused on the error compensation technique for its ability to correct ball screw error effectively rather than the capabilities of careful machine design and manufacturing. Significant amounts of researches have been done to realtime error compensation. But in this paper, we developed a series of cooling methods to get thermal equilibrium in the ball screw system. So we find the optimum cooling type for improving positioning error which caused by thermal deformation in the ball screw system.

Research on Thermal Error Compensation Technique of the Screw

In the system of the machine tool, the position error is directly affected by the thermal deformation of ball screw. Screw system is a complex thermal system, which is affected by the processing conditions, the processing cycle, the use of cooling fluid, and the surrounding environment. Due to non-linear and interaction of the thermal error, a RBF network thermal error model is proposed in the paper and the model is tested in XHFA2420 large machining center.

Theory analysis and system identification methods on thermal dynamics characteristics of ballscrews

Empirical model of machine tools on thermal error has been widely researched, which can compensate for thermal error to some extent but not suitable for thermal dynamic errors produced by dynamic heat sources. The thermoelastic phenomenon of unidimensional heat transfer of ballscrews influenced by changeable heat sources is analyzed based on the theory of heat transfer. Two methods for system identification (the least square system identification and BP artificial neural network (ANN) system identification) are put forward to establish a dynamic characteristic model of thermal deformation of ballscrews. The model of thermal error of the X axis in a feed system of DM4600 vertical miller is established with a fine identification effect. Comparing the results of the two identification methods, the BP ANN system identification is more precise than the least square system identification.

A Study to Suppress Machining Error due to Thermal Deformation of Ball Screw of Machine Tools

In order to compensate the thermal deformation of the ball screws due to the heat generated during operation, the ball screws are generally given tension load when the machine tools are assembled and shipped. Although this empirical practice has been widely adopted, the effect of tension load given to the ball screws is not clarified quantitatively. The present paper deals with theoretical and experimental analyses of the effect of the tension load on the thermal deformation of the ball screw and the deviation of the position of the nut. It has been clarified that there exists a position of the nut along the ball screw where its deviation is zero despite the thermal deformation of the ball screw, and this position is determined by the ratio of the rigidities of both supporting brackets. A practical method is also presented to reduce the machining error due to the thermal deformation of the ball screw.