Chapter 4 - Design for dynamic stiffness
Chapter 10 - Design for manufacturability

Parcel Sorting System – PosiSorter concept



A parcel sorting system consists of a conveyor system for transport and a sorting mechanism to direct the parcels to intended locations.


The PosiSorter consists of a conveyor with moving profiles that transports parcels along a number of sorting destinations. A sorting mechanism with a switch can direct sliding blocks sideways to guide a parcel to the required destination aside of the conveyor. In each of the moving profiles a sliding block is integrated. Multiple sliding blocks are used to push a parcel off the conveyor to one side or the other. The siding blocks have a vertical pin beneath them in order to direct them by a stationary switch mechanism and a rail underneath the moving profiles. A certain stiffness of pin, block guidance, rail and switch are required to make the blocks follow the intended profile. The passive sliding blocks and the stationary switch and rail create a high dynamic stiffness which is required for the high speed switching, which in turn is required for allowing a high moving velocity of the conveyor. In practice however the pins can collide with the switch, if the pin is not following the swich profile from the beginning. This can be caused by play in which case some compliance is advantageous to keep the collision forces within bounds. The complexity of the moving parts is kept to a minimum. The profiles have pretensioned sliding linear guidances. Lifetime reducing vibrations of a moving actuation mechanism, with power and signal cables are avoided.


High dynamic stiffness at low complexity is achieved by a relatively simple mechanism that moves with the conveyor, while the actuated switching mechanism is on the non-moving static frame.

Figure 1.  The PosiSorter working principle, sorting out parcels by shifting multiple blocks on individual sliding rails to one side or the other to.

Figure 2.  A switch directs the pin of a sorting block on a linear guide sideways. The switch is mounted on a static frame on the non-moving world (in orange). The frame guides the block.

Figure 3.  Multiple blocks direct a parcel to its destination.

Developed by Vanderlande

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Design principles