Investigation and improvement in peak failure load of hot staked joints in starter motor armatures using complementing problem-solving tools

摘要

Hot staking is the preferred process for conductor-commutator joints in the DC motor armatures as it is versatile and cost effective. But however its application is limited by the peak failure load of the joint which depends only on the mechanical contact as there is no amalgamation or diffusion of metals in the faying surface. This study investigates the mechanical joint strength and found its variation has a positional pattern which is significantly related to similar pattern in electrode heat. A hypothesis for the similarity is reasoned and validated, which enabled evolution of a feasible solution to have differential input of energy compensating the variation in heat. This resulted in overcoming the limitation of joint strength in introduction of hot staked armatures to new applications. The use of Shainin clue generating tool, Relations diagram and visualizing the physical mechanism complemented the problem solving approach in causal clue exploration, hypothesis reasoning and solution development.