Threaded Closure Process with Force Output Graphs

Here we see a dynamic simulation of an assembly process involving the capping of a bottle.  Of primary interest is the torque and thrust loading developed on the system as the cap is spun onto the bottle.

The components of this simulation include capper equipment head, the bottle cap with female threads, and the bottle neck with the male threads.  The model is fully three dimensional including a free floating cap that is constrained by contact with the capper head and  bottle neck.  The bottle neck is fixed at its base and the capper head is controlled to move axially and rotate to effect the closure.

The capper head is modeled with a hyperelastic rubber material while the bottle components are elastic-plastic materials.  The bottle cap and bottle neck are modeled with elastic-plastic materials.  This allows for any localized plasticity in the threads.  The friction of the cap to head and cap to neck are controlled seperately to reflect the rubber to plastic and plastic on plastic interaction.  The inclusion of friction and plasticity allows the sources of work to be properly differentiated and the efficiency of the system can be reviewed.

A plot of the torque (red curve) and axial force (blue curve) shows their time variation as the cap is assembled onto the bottle neck.  This video shows the stress distribution in the components with the capper head and bottle cap sectioned for visibility.  Other results are available such as the contact pressure between the bottle cap and neck as well as any permanent plastic strain that occurs.