Redesign of an Assembly Line Stop Mechanism for an Automated Palletized Transport System 980745
A description is provided detailing the results of the quality function deployment process used to identify customer needs and requirements. Through this process two primary project goals were developed consisting of integrating an electrical-solenoid actuated device into existing space constraints and providing cost reduction alternatives.
A static and dynamic analysis was initially required to find the boundary conditions of the external forces imposed on the existing pneumatic device while being subjected to multiple pallets impacting the stop block assembly. Further static analysis was conducted to find the internal forces imposed on the stop arm subassembly in order to properly size the electrical solenoid. Subsequent research into various solenoids led to two solenoid manufacturers evaluated by means of a design evaluation matrix. Size and cost constraints placed on the design team precluded consideration of larger solenoids that produced comparable performance capabilities and unrealistic manufacturing plant electrical power requirements.
Three experimental laboratory tests of the existing design were conducted to better understand the performance of the existing design. The first laboratory test showed that the frictional characteristics of the stop arm pallet interface were much higher than allowable for conventional solenoids integrated into the existing stop block assembly. A second test revealed the kinematic motion of existing stop block geometry that produced undesirable motions resulting in higher frictional forces. The final test was conducted to find the ultimate strength and fracture mode of the stop block assembly. Results revealed a potential critical fracture area in the stop arm within a radius area near a highly stressed region.