Joint structure between the wall elements of a magnetically shielded room
The present invention discloses a joint structure between the wall elements of a light-weight magnetically shielded room. In the joint structure, the end of the aluminum plate of the element is stepped and its surface roughened. In addition to this, the aluminum plate is coated, for example, with tin to improve the electrical contact. The joint includes μ metal plates which are used to make a magnetic contact between the μ metal plates of the elements. The compression force achieved by means of bolts is transmitted to the joint by means of an aluminum moulding. The non-continuous compression force is balanced over the entire joint area by using presser rubbers. The joint structure is protected by means of supporting profiles which are used to electrically couple the thinner aluminum plate of the sandwich type wall element to the thinner aluminum plate of an adjacent element. The thinner aluminum plate and the supporting profile can also be coated, for example, with tin to improve the contact.
1. A joint structure operatively connected between a first wall element and a second wall element of a magnetically shielded room, wherein both wall elements operatively connected in order from inside of the shielded room to the outside of the shielded room, comprising:
a first μ metal plate;
a first aluminum plate;
a second μ metal plate;
a second aluminum plate;
wherein the joint structure further comprises, operatively connected in order from inside of the shielded room to the outside of the shielded room:
a bolt;
a first supporting profile;
a first presser rubber for balancing a compression force in the joint over an entire joint area;
a first μ metal molding for making a magnetic contact between the first μ metal plates;
a first perforated aluminum molding;
the wall elements, wherein there is a first notch on an edge of the first aluminum plate of the first wall element, and a second notch on an edge of the first aluminum plate of the second wall element, a roughened surface and a first coating on a contact surface of the first aluminum plates, so that the first aluminum plates of the elements match, thereby forming a tongue-and-groove joint, the first aluminum plates being disposed on a same plane;
a second perforated aluminum molding;
a second μ metal molding for making a magnetic contact between the second μ metal plates;
a second presser rubber for balancing the compression force in the joint over the entire joint area;
a second supporting profile for strengthening the joint structure and making an electrical contact between the second aluminum plates; and
an opposing piece for the bolt,for pressing the joint structure together.
2. The joint structure as defined in claim 1 , wherein the first coating is made of tin.
3. The joint structure as defined in claim 1 , wherein the joint structure further comprises:
a second coating on a surface of the second aluminum plates to improve the electrical contact.
4. The joint structure as defined in claim 3 , wherein the joint structure further comprises:
a third coating on a surface of the supporting profile to improve the electrical contact.
5. The joint structure as defined in claim 4 , wherein the third coating is made of tin.
6. The joint structure as defined in claim 3 , wherein the second coating is made of tin.
7. The joint structure as defined in claim 1 , wherein the opposing piece is a threaded moulding or a combination of a nut and a base plate.
8. The joint structure as defined in claim 1 , wherein the first and second presser rubbers have a wavy cross section at least on one side thereof.