The Use of Segmented Dies for Plastic Forming the Heads of Bolts on Forging Machines

Abstract

Fasteners such as bolts constitute an important group of products in the metal industry. Owing to their wide industrial use, methods ensuring dimensional accuracy, process repeatability, and low manufacturing costs are crucial. Bolt heads are most commonly formed by cold forging. The aim of the article is to analyze the application of segmented dies for forming bolt heads with a concave–convex lateral surface in the cold forging process. The authors seek to demonstrate that the use of such tooling enables high dimensional accuracy to be achieved without the need for additional machining. The obtained results indicate that, the modular design of the dies makes it possible to obtain the required geometry within a five-operation process, which shortens the production cycle, reduces tool wear, and lowers manufacturing costs, while improving overall process efficiency. The shape of the head can be effectively controlled through strategic modifications of die geometry, careful sequencing of dies, and the implementation of supplementary radius smoothing during rolling. The presented approach constitutes a significant contribution to the development of cold forging technology, offering more economical and efficient methods for manufacturing fasteners with complex geometries.