The breakage of customized graphite electrode connector products is partly due to operation and control, but the quality problem of electrode itself is also the decisive factor for the breakage of customized graphite electrode connector.

Internal quality reasons of customized graphite electrode connector products

(1) The reason why the connector of customized graphite electrode is broken is that the connector plays a key role in electrode steelmaking. The quality of the connector is directly related to the use of the electrode in electric furnace steelmaking. The connection area formed by graphite electrode and joint is not only the part with large and complex electrical, thermal and mechanical loads, but also the part with common fracture. According to relevant data, in electric furnace steelmaking, more than 80% of electrode use accidents are caused by joint breaking or loosening tripping. As far as the quality of the joint itself is concerned, there are mainly the following reasons for the fracture: if the bulk density of the joint is low, the strength is generally low, and it is easy to break when in use; The resistivity is high, and the temperature at the joint increases rapidly when powered on, which will cause large thermal stress at the joint at the electrode connection and increase the probability of fracture; The bending strength of the joint is not enough; The internal crack joint is mixed into the finished joint to form a major hidden danger; There is no reasonable matching between the machining accuracy index of the joint and the electrode, and it is also easy to break.

(2) The reasons for the breakage of customized graphite electrode connector products are usually that the probability of electrode breakage is low. The main reasons for the breakage of custom-made graphite electrode connector are as follows: the electrode screw hole has quality defects; The bulk density and strength of the electrode are not enough; The electrode does not match with the joint index and machining accuracy; The deep crack at the end of the electrode is caused by the poor thermal shock resistance of the electrode; In addition, the electrode with internal transverse crack is mixed into the finished product and is not detected, so there is a great risk of breaking.

Preventive measures and operation suggestions for customized graphite electrode connector products

1. Preventive measures against breakage of customized graphite electrode connector products in smelting operation

(1) Reasonable distribution structure: the distribution of various scrap steel in the material basket and the condition of adding into the furnace shall be reasonably configured to avoid the light and thin steel materials forming a group on the top of the furnace and difficult to go down, and to avoid the electrode broken by the collapse of large scrap steel.

(2) During smelting, especially when it is close to melting, carefully observe the distribution of unmelted furnace materials. If the bridge structure has been formed, the furnace charge should be allowed to collapse under the condition of power failure and the electrode has been raised to a high level by means of oxygen blowing or physical swing or shaking, so as to avoid the electrode being broken by material collapse.

(3) The graphite electrode connector products shall adopt the strength suitable for the process requirements. The connecting electrode shall adopt nuts with appropriate strength, be cleaned, and use special clamping tools. Before replacing the electrode and lifting, the lifting ring must be fastened to ensure that the lifting ring is in close contact with the electrode. In order to ensure the cleanness of the interface, it is required to keep the protective end cap of the new electrode until the lifting ring is installed.

(4) The electrode holder shall avoid being caught in the white line between the electrode connections. The electrode connection shall not be above the electrode holder. The electrode holder shall not be clamped on the open socket or the socket with lifting ring.

2 preventive measures for customized graphite electrode connector in control process

(1) After high-voltage power transmission, observe whether the no-load voltage of the secondary short network is balanced (determined by the insulation resistance of the three-phase short network to the ground, and the unbalanced voltage should be within 10%).

(2) Before the automatic lowering of the electrode, confirm that there is no non-conductive object in the scrap layer directly below the electrode.

(3) After the first phase electrode contacts the scrap, observe whether the secondary voltage of the phase electrode drops immediately.

(4) When an arc occurs at a phase electrode, whether the secondary current display of the phase electrode can be seen (the pointer of the ammeter swings greatly).

(5) Regularly check whether the braking force and system delay coefficient of electrode hydraulic driving mechanism change.

In terms of internal quality of electrode, the influence of key technical indexes of electrode (joint) on electrode fracture in smelting process has been studied in detail by many scholars. It is worth noting that the China Carbon Industry Association has conducted random inspection on the product quality of member enterprises, and compared the test indicators of product random inspection with the national standards and the enterprise standards of foreign well-known enterprises. From the inspection indicators, most of the indicators of all tested products meet the yb-2000 standard, and some indicators have reached or close to the enterprise standards of foreign companies. However, the actual smelting effect of domestic ultra-high power graphite electrode is obviously different from that of foreign products of the same specification. Therefore, there is a certain one sidedness in judging the quality of electrode (joint) only by the physical and chemical indexes of electrode (joint). The matching of our products with the smelting process, furnace structure, smelting steel grade and other comprehensive factors of different customers should be fully considered, Establish a set of scientific and reasonable electrode production and technical application scheme.

conclusion

(1) The electrode of electric furnace can be broken due to material collapse, resonance, non-standard clamping operation, abnormal condition of electrode regulator and hydraulic driving mechanism of electrode regulator, improper control measures of electrode internal quality and other factors.

(2) By taking corresponding technical and management measures for the factors such as distribution structure, electrode clamping, no-load voltage of secondary short network, non-conductive object, secondary current, braking force of electrode hydraulic driving mechanism and system delay coefficient, the phenomenon of electrode breaking can be significantly improved.

(3) Based on the scientific matching of electrode type and smelting process, the quality of electrode type and smelting furnace should be fully considered.