Modeling the Static and Dynamic Behaviors of a Large Heavy-Duty Lathe Machine under Rated Loads

Abstract

The static and dynamic performances of a machine tool structure are considered to constitute the primary factors affecting the load-carrying capacity, geometric accuracy and surface precision of the workpiece. The machining performance of a large machine tool under stable conditions is effectively determined by its dynamic response to the cutting force at low-frequency excitation. This study, therefore, investigated the static and dynamic characteristics of a large heavy-duty lathe machine tool in which the headstock and tailstock comprised critical component modules supporting a large workpiece during low-speed machining. Using a finite element model, the influences of the structural modules on the static and dynamic characteristics of the lathe were analyzed, considering the effects of the workpiece load. The results indicated that the fundamental vibration modes of the lathe were primarily dominated by headstock, tailstock, and workpiece behaviors. The maximum compliances of the lathe under the rated load were found to occur at relatively low frequencies (22, 40.7, and 82.7 Hz) and increase with the reduction in workpiece weight. Notably, these modal frequencies were significantly higher than the maximum rotational speed of the spindle (450 rpm). In addition, the dynamic rigidity corresponding to the rated speed was higher than that induced at the natural frequency. These results indicate that the subject lathe possesses sufficient capacity to sustain the cutting load during stable turning machining. This study can, therefore, help designers improve the performance of machine tools for future fabrication.

Case study of vibration in a mobile milling machine

“…However, the amplitude of the FRF is noticeably higher than that of modern Computer Numerical Control (CNC) machines. Indeed, references [9]- [11] all present machines with tool-point FRFs that have maximums lower than 0.17 µm/N. The present machine resembles another mobile machine tool presented in [1], [2] which has a flexibility value of 0.3 µm/N.…”

“…However, the amplitude of the FRF is noticeably higher than that of modern Computer Numerical Control (CNC) machines. Indeed, references[9]-[11] all present machines with tool-point FRFs…”

Analysis of Dual-Driven Feed System Vibration Characteristics Based on Computer Numerical Control Machine Tools: A Systematic Review

“…When subjected to complicated external dynamic loads, joint component substructures are prone to micro-vibration with multi-directional degrees of freedom (DOFs). The joints will be able to show off the crucial characteristic of flexible connections by storing and dissipating energy and demonstrating elasticity and damping [57][58][59]. Statistics indicated that joint factors like damping and stiffness account for 30% to 50% of stiffness and 90% of the CNCMT's dynamic performance damping.…”

Modelling and Analysis of Dynamic Servo Error of Heavy Vertical Machining Centre Considering Nonlinear Factors

“…When there is no tracking error in the servo axes, the multi-axis servo system will not exhibit a contour error. This is due to the fact that the tracking error is mainly affected by the closed-loop control and the hardware/machining conditions such as the static stiffness and the dynamic behaviour of the servo system [6]. In order to study the dynamic servo error of a machine tool, it is first necessary to develop a model of the servo feed system for each motion axis, primarily by modelling the servo drive system and the mechanical transmission system, and then to analyse the resulting characteristics of the servo axis with different factors, and the contour error in multi-axis coordinated motion.…”