They're only an inch long, Keith, so more likely to be the bolt used to join kitchen cabinets to one another. The ones that go through the pre-drilled holes in the side panels. They're about 5mm diameter.
Can't find an illustration for them. Got millions spare in the workshop so may have to take a photgraph and post it, although that ain't gonna help the OP in naming them!
Think it's this (and suggest asking for a source for them on a kitchen fitter's forum?)...