To make sure that the graphite electrode can be used continuously in electric arc furnace, threaded nipple is adopted to connect two or more electrodes. However, it needs to avoid the graphite electrode break caused by improper nipples connection.
Graphite electrode nipple production process
The manufacturing process of graphite electrode nipple is the same as that of graphite electrode, forming the nipple shape in the last step machining. Because of the high-quality demands, need three or four impregnations to improve the density and flexure strength, so its production cycle is longer than graphite electrode.
Graphite electrode nipple standard
Graphite electrodes for electric arc furnaces - Dimensions and designation
Specifies the dimensions of turned and threaded cylindrical graphite arc furnace electrodes and graphite electrode pins for use as full graphite electrode columns on arc furnaces.
Graphite electrode nipple specifications
Graphite electrode nipples are divided to T3 and T4 according to the number of threads, 3 threads per inch and 4 threads per inch. The flank angle is 60°, and the taper is 1:3 (that is, the half cone angle is 9.46°)
Dimensions of Pins and Sockets
Tolerances for Sockets and Pins
Source: International Electrotechnical Commission (IEC). If there are special specification requirements, both sides consult supply and demand.
Special gauge for graphite electrode thread measurement
Use tools to measure the taper, the pitch diameter, the coaxially of the outer circle of the electrode thread.
- The reference working ring gauge RA, the big-end working ring gauge RC, and the small-end working ring gauge RB are used to detect the external thread of the graphite electrode nipple. When measuring the thread of the nipple, the taper value and the pitch diameter of the thread can be directly given.
- The large-end working gauge PB and the small-end working gauge PA are used to detect the internal thread of the graphite electrode. When measuring the electrode thread, it can be directly given the taper value of the pitch diameter, the pitch diameter and the coaxial deviation between the outer circle of the electrode and the thread.
The above is the advanced graphite electrode treads measuring tool manufactured by China, there is another type of graphite electrode thread special gauge is produced by Germany.
The post-processing inspection of the graphite electrode thread is remarkable important, as the threads are used to connect, need to withstand strong currents, especially the high-power and ultra- high-power electric arc furnace steelmaking, strong electromagnetic force, intense vibration, and inadequate contact of the nipples will cause electrode breaks.