Model of contact between rollers and sprockets in chain-drive systems

Abstract

A model of a roller-chain drive is developed and applied to the simulation and analysis of roller-chain drives of large marine diesel engines. Two different ways of modelling the contact between the rollers and sprockets are presented; one using a circular shaped tooth profile and the other using the shape of a real tooth profile. The main components of the roller-chain drive model include the sprockets with different sizes and the chain made of rollers and links, which are represented by rigid bodies, mass particles and spring-damper assemblies, respectively. The contact between the rollers and the sprockets are represented by a continuous contact force. The models proposed effectively represent the polygonal effect always present in this type of drive. The numerical results from the simulations are compared with analytical results, for simplified models. The model with a real tooth profile proves superior to the model with a circular tooth profile. IntroductionThe work presented is a further development of the methods used in [11]. The purpose is to suggest a model that improves the simulation-based prediction of roller-chain forces. In particular, the model should improve numerical stability, link engagement with sprockets and the contact forces between rollers and sprockets.The dynamics of the roller-chain drives are characterized by a complex behavior with impacts between the chain links and sprockets, and by discontinuities in the system components' velocities giving rise to transversal and longitudinal vibrations of the spans of the chain. These events are the factors responsible for part of the noise presented by mechanical devices that use roller chains and ultimately by the wear of the roller-chain drives. Though roller chains have been used for a long time as a reliable mechanical component to transmit power and to handle materials mechanically, most studies of their dynamical behavior were done in the last decades, see e.g. [4,5,12,14,17,18]. For earlier work, see e.g. [2,9]. The main reason for this situation is that the dynamic behavior is very complex, making it impossible to find general analytical procedures able to describe the problem thoroughly. With the development of fast computers, some recent efforts have been put forward in order to better understand different aspects of these mechanical components, see e.g. [17]. In a review of the state-of-the-art in [18], many of the investigations that have been carried out are summarized and it states that integrated models describing the full dynamics of the system are necessary, in order to accurately describe the interrelation between the different elements in the chain drive system.The major difficulties in the study of the roller-chain drives are related to the roller-chain wrapping around the sprockets, which forms a polygon. This effect, called polygon action, together with the impact between rollers and sprockets are responsible for the noise andThe applications represent the ongoing work that resulted from many fruitful discussions with Per ...

Kinematics of roller chain drives — Exact and approximate analysis

“…multibody simulations are carried out using the program described in [11,12]. In the multibody model the mass of the chain is lumped at the roller center locations, and springs and viscous dampers with constant stiffness-and damping coefficients model the chain links.…”

“…Numerical analysis of roller chain drive systems has been developed using a multibody modeling approach by Pedersen et al [11], which can take into account non-linear dynamic coupling, exact tooth geometry and impact phenonema [12]. A general methodology for planar models of multibody chain drives has been suggested by Pereira et al [13].…”

Kinematic and dynamic modeling and approximate analysis of a roller chain drive

“…In order to access the potential similarity with chain drives in operation, the kinematic results are compared with results from multibody simulations, which includes both greater detail of the chain drive geometry and dynamic effects. The multibody simulations are carried out using a simulation program developed by Pedersen et al [8], which includes a detailed modeling of the tooth geometry and the flexible contact between teeth and chain rollers [9].…”

“…Simulation results are obtained using a simulation program which include dynamic effects, flexible contact, and the exact geometry of the sprocket teeth [8,9]. These results demonstrate that a real roller chain drive must include compliant components for a tensioned chain to wrap around rotating sprockets, as the sprockets are effectively eccentric.…”

Enhanced chain dynamics in loop-sorting-systems by means of layout optimization and a kinematic model of the polygon action

“…A chain drive model is presented in Pedersen (2005) and Pedersen et al (2004). Assuming each link of the chain to be lumped masses the chain is modeled using a force element approach.…”