What is the mutual opening rate of the key?

There is a concept of "interoperability rate" in the production of locks. The mutual opening rate has corresponding national standards according to the use of locks. The difference between safety requirements is from a few percent to a few thousandths, a few thousandths or even more. There are.

When the anti-theft door lock is produced, according to the processing precision and the number of beads, the manufacturer knows the maximum number of combinations in advance, and according to this arrangement, the continuous cycle production is combined with the mutual opening rate. The mutual opening ratio refers to the ratio of the number of locks that are opened to each other (the percentage of the number of times that the number of openings is compared with the total number of trials) in the same batch of locks.

The less the lock that a key opens, the stronger the safety and reliability of the lock. The strength of well-known lock brands is strong, and the mutual opening rate of locks is only tens of thousands of parts. However, some manufacturers with irregular and incompetent strengths may reach a fraction of one-tenth, which means that these manufacturers may only have dozens of sets. A mold that produces locks.

At present, the country divides the security door lock cylinder into three levels: Class A, Class B and Class B. According to the corresponding national standards, the mutual opening rate of A-class locks should be ≤0.03%, the three locks of 10,000 locks are the same; the mutual opening rate of B-class locks is ≤0.01%; the mutual opening rate of super-B locks is lower. About ≤0.0004%, that is, 4 out of a million locks are the same.

How is the mutual opening rate of locks determined? You can take a look at the structure of the most common marble locks:

The principle is actually very simple. The lock in the above picture has five pairs of marbles (ie, five upper marbles and five lower marbles), which can slide up and down in the corresponding marble holes. When the correct key is inserted, the five upper marbles are retracted from the lock cylinder to the lock body, just in line with the contact surface of the lock cylinder and the lock body, and the key can be unlocked by rotating the lock cylinder. If the keys don't match, the marbles will get stuck at the seams of the two, and the keys won't open.

The number of teeth of the same group of locks corresponding to the key is determined by two factors, one is the number of marble holes, and the other is the number of marbles. The number of marble holes has been said above. The number of marbles means that there are several types of marbles (the sum of the lengths of the upper and lower marbles is determined), and the length is not arbitrary, but has a certain level difference. So the key has several different tooth counts and it's easy to calculate.

For example, when the number of marble holes is 4 and the number of marbles is 5, the number of teeth is 5^4=625; when the number of holes is 6, and the number of marbles is 5, the number of teeth is 5^6=15625. (The actual number of teeth in the production is less than the theoretical value, because some special teeth are removed).

The more the number of teeth, the lower the rate of mutual opening.