Structural–kinematic synthesis of a long-dwell, allowable transmission angle two-rod mechanism for a knuckle joint press

The main advantage of the proposed knuckle joint press mechanism over traditional crank presses is the extended dwell time, which enables better control over the stamping process. This allows for precise deformation, improving product quality. Additionally, the optimized force transmission in the proposed design reduces mechanical losses, leading to improved energy efficiency. These improvements make the press more suitable for high-demand applications where precision and durability are essential, thus providing a significant advantage over existing crank presses. This study focuses on the synthesis of a knuckle joint press utilizing mechanisms with unevenly distributed rods, which belong to the category of variable contour mechanisms. The objective is to develop a systematic method for synthesizing such a mechanism, specifically targeting the task of maintaining the stability of the working link with predetermined parameters. The synthesis approach involves reducing the mechanism’s class and implementing a step-by-step kinematic synthesis method. The reduction in class is based on the original double-rod mechanism of the fourth class, while the kinematic synthesis of the third-class mechanism is performed in two stages: optimal synthesis of the closed kinematic chain and interpolative synthesis of the kinematic linkage. By following this methodology, a third-class mechanism with a prolonged dwell time is successfully synthesized, and a two-rod crank press with similar kinematic characteristics is designed based on its scheme. Additionally, algorithms and programs for kinematic analysis of the synthesized mechanisms are developed, demonstrating the reliability of the results in achieving the desired kinematic characteristics for the crank press. The obtained results have practical significance and can be applied in the development of high-precision presses for metal forming, ensuring improved product quality and energy efficiency in industrial applications.