Purge and Archive process is very complicated which purges the work objects based on some criteria like Resolved, Aged and belongs to selected class groups. It also purges dependent objects associated to work objects like Links, Attachments, History, Child cases.
If your requirement is to Purge and Archive the un-resolved work objects then you need to be very careful in your implementation as it is going to delete the work objects with proper archive of complete data.
If your requirement is just to archive the un-resolved work objects without Purge/Delete then you can create a Rule-Admin-Product rule through which you can archive the un-resolved work objects using "Class instances to include" section with Listview filter and When filter. Using these filters you can perform the archive of the un-resolved work objects.