Pressure ring assembly for contact shoes in an electrode system

1. A pressure ring assembly for contact shoes in an electrode system of an electric arc furnace provided with at least one electrode column assembly, the lower part of which electrode column assembly comprises a contact shoe ring formed of a plurality of contact shoe elements, a pressure ring formed of a plurality of pressure blocks connected to each other to form an annular ring surrounding the contact shoe ring, the pressure blocks of said pressure ring being provided with hydraulic bellows by which the contact shoe ring is pressed against the steel mantle of the electrode, and a heat shield located above the pressure ring in the axial direction of the electrode column assembly, said heat shield formed of a plurality of heat shield segments connected to each other, wherein an elongated groove is formed on both substantially vertical side edges of each pressure block, so that in two adjacent pressure blocks said grooves are facing and opening towards each other, said grooves being wider at the bottom of the grooves than at the side edges of the pressure blocks, that an elongated lock bar is placed in the grooves of two adjacent pressure blocks to join said pressure blocks with each other, each lock bar being transverse to its longitudinal direction thicker at its both sides than in the middle, so that the form of the lock bar essentially matches to the form of the grooves of said two adjacent pressure blocks, and that each lock bar is locked in place in the grooves by fastening bolts through holes in the pressure blocks, wherein both the lock bars and the grooves are provided with bezels matching each other to form a dove-tail like joint between them, wherein the fastening bolts extend from the outer surface of each pressure block to the lock bar into which said fastening bolts are threaded.

2. The pressure ring assembly as claimed in claim 1 , wherein the matching bezels are pressed against each other when the fastening bolts are tightened, so that in the joint formed thereby forces are transmitted through the bezels to the lock bar.

3. The pressure ring assembly as claimed in claim 1 , wherein the grooves in the side edges of the pressure blocks extend from the upper end of each pressure block downwards near to the bottom end of the same where said grooves are closed by a shoulder.

4. The pressure ring assembly as claimed in claim 1 , wherein the lock bar is made of antimagnetic material.

5. The pressure ring assembly as claimed in claim 4 , wherein the material of the lock bar is austenitic steel.

6. The pressure ring assembly as claimed in claim 1 , wherein the fastening bolts and the holes made for them in the pressure blocks are covered with caps.