Stiffness model of machine tool supports using contact stiffness

Abstract

The stiffness of machine tool supports should be properly designed for reducing both the ground disturbance vibration and the drive disturbance vibration. However, the stiffness cannot be easily calculated from the geometry and material properties of the support. In this paper, a 3D stiffness model of a machine tool support is proposed using contact stiffness. The stiffness in each direction is assumed to be determined by the contact stiffness at the interfaces and the bulk stiffnesses of the supports and the floor. The contact stiffness model proposed by Shimizu et al. is expanded to determine the contact stiffness in the normal and tangential directions of an interface. In the proposed model, the contact stiffness is obtained by multiplying the unit contact stiffness by the real contact area. The contact stiffness of concrete is experimentally investigated to estimate the stiffness between machine tool supports and the floor, and it was observed to be the primary determinant of the stiffness of interfaces between metal and concrete. Moreover, the unit contact stiffness of concrete is discovered to be less than 1/10 of those of the metals that were used for the study. The natural frequency and vibration mode shape of a model machine tool bed are also experimentally measured and used to verify the proposed stiffness model. The comparison of the results obtained from the two procedures shows that the natural frequency and vibration mode shape of a machine tool bed can be predicted using the proposed stiffness model.

Analytical models for machine tool motion behavior assessment bench mark subjected to great earthquake

“…For the hardest earthquake situation, a metal-metal interface foundation was chosen to analyze the structure motion during seismic activity. It must be highlighted that a metalconcrete interface shown a 1/10 of the support stiffness of a metal-metal interface in previous studies [13]. On the other hand, Fig.…”

“…In addition, some leading organizations standardized the machine tool anchoring for resisting earthquake disaster by avoiding moving, rotating or falling [11] [12]. however, it was viewed that although anchoring approach considerably safe for preventing machine tool motion during seismic activity, the manufacture production area could be affected [13]. meanwhile, the deformation of machine tool due to large earthquake acceleration out of clearance range and its prevention strategies have not been discussed [14].…”

Risk Assessment Criteria for Machine Tools Subjected to Large Earthquake Hazards: A Proposal

“…The selected foundation, a metal-metal interface, was meant to analyze the harshest foundation conditions during an earthquake that could lead to movement of the structure. Here, it must be noted that a metal-concrete interface exhibited a 1/10 of the support stiffness of a metal-metal interface in previous researches [16]. On the other hand, the friction coefficient of the different foundation conditions, shown in Fig.…”

“…However, given that the usage of fixed mounts or concrete anchoring on machine tools reduces the flexibility of the production area, screw jacks and leveling jacks are common even in seismic prone areas, and research regarding the role of these mounts in machine tools has been explored in recent years [16]. This research proposes risk assessment criteria that contribute to the selection of proper anchoring.…”

A method for stiffness tuning of machine tool supports considering contact stiffness

“…To address this problem, a model based on the contact stiffness of machine tool supports has been developed in one of our previous studies [19]. In this paper, a method for tuning the stiffness of supports is proposed using the developed model.…”