You're basically talking about extra-large switchblades (of the folding, rather than spring-out, variety), which is both good and bad. These weapons are practical at the smaller scale, but I see three potential problems with scaling them up.
One is that it will wreak havoc with your internal balance. The weight of the spring mechanisms on the blade, combined with hollowing out the hilt to make room for the folded blade, will move the center of balance forward. Slashing swords tend to have their point of balance way back in the hilt, for greater control; moving it forward makes it more of a chopping weapon like an axe, which requires a different fighting style. A stabbing sword might actually be more practical here, since it doesn't care as much about balance.
The second issue is that the hinges themselves are weak points, in that they can both be broken relatively easily and have the potential to fold up in combat. This is especially bad since your balance problem, as mentioned above, is biasing your weapon towards big power strokes. The best way to solve this is to minimize the number of hinges, but that makes your whole package longer. Having a 50cm "hilt" on a sword isn't inherently bad, but it will mean extra practice to get used to it.
The third issue is the raw force of the spring(s). Switchblades are small, but the mainspring can still put out a surprising amount of force when triggered. You're talking about a blade 10x as long, probably several times thicker in cross-section, with a proportionate increase in the amount of force it takes to swing it out. You'd have to be careful not to drop them just from the sudden torque.