I have two Acer 6312, one in bad condition. These are hammer on membrane keyboards. One spring pushes the hammer down onto the membrane and the key up after that. The other flat one makes the click. Not sure if I understood the mechanism completely.
I wonder whether they licensed the interface from Alps. The stem looks very similar and the caps are interchangeable.
These are dishwasher keyboards. With the 'board disassembled the switches are open and can dry quickly. I didn't put the membrane and the pcb in back then, but would today. Avoid the dry cycle.
Yours looks like a different construction than the Acer. The keys appear to be snapped into the upper half of the housing. That's a good idea actually.
You can remove the switches from the top without disassembling the keyboard. For ex. to exchange a broken key.