Abstract

The purpose of this project was to analyze a vise-grip clamping device and determine the relationship between the input force and the output (clamping) force. A skeleton diagram was created for the mechanism, which is a coupler-driven four-bar mechanism. Equilibrium equations were derived from free body diagrams, and the system of equations was solved for the mathematical relation between input and output. It was found that maximum, in fact infinite, mechanical advantage is gained when the coupler is in-line with the ground link. This configuration forms the basis of the mechanism’s clamping ability: when the mechanism is “over center,” in this configuration, only a minimal amount of force is needed to maintain clamping pressure. Finally, it was determined that the adjustable sliding joint is useful in obtaining a wide range of clamping angles.

A vise-grip clamping tool was analyzed in this project. A vise-grip is an example of a couplerdriven four-bar mechanism. In order to analyze the relationship between the input force and the clamping force, a skeleton diagram was first constructed to study the kinematics of the mechanism. Second, a force-balance analysis was conducted on the links of the vise-grip in order to derive a mathematical equation relating input force and clamping force.

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