Thread rolling machines traditionally have no way of monitoring for die failure. During long-term use, die failure can develop as small imperfections in the surface of the die such as fissures, cracks, or fish tails in the die surface. These features produce very minimal force signatures or vibration. With vibration or acoustic based approaches, it is almost impossible to monitor when the thread is rolled on small diameter stud bolts, or other small threaded product. Our approach is unique in that it non-invasively monitors the force transfer through the die packing with extreme sensitivity. We are resolving forces related to minute failures on the die surface, measuring sub Newton force on top of 10,000-20,000 lb static roll force.
The product that is being rolled on this Waterbury #20 machine is small diameter thread products for titanium and Inconel bolts for aerospace applications. In small diameter threads, the existence of dye imperfections are failures, and can lead to product rejection, folds in the threads, or other features that are unacceptable to the end user. The ability to monitor the force in the die packing is a unique approach to being able to predict and prevent the use of worn and failed dies without operator intervention. This saves time, and saves the operating company money by preventing the manufacturing of scrap product.