Using electrical furnace to heat and stretch the optical fiber preform or core rods

it is difficult to control the diameter during the start and finish period

and influence the stretching accuracy and use ratio. In this paper

from the point of view of heating and softening of the rod

it is pointed out that different parts of the rod in the axial direction during heating and stretching have different degrees of heat absorption and accumulation

due to factors such as space

time and material differences. The cone shape of the rod body is changed due to the viscosity change

which makes it difficult to control the extended outer diameter. In this paper

the influence principle of heat accumulation phenomenon is analyzed

and the corresponding technical scheme of outer diameter control is put forward.