Cold billet preheating and feeding device for production of steel bar with diameter of 18-40mm

The utility model discloses a cold billet preheating feeding device for production of steel bars with the diameter of 18-40 mm. The cold billet preheating feeding device comprises a circulating oil storage tank, a heating furnace body, a smoke exhaust pipe and a heat preservation bin, a feeding port is formed in the first end face of the heating furnace body, and a furnace entering roller way is arranged on the feeding port; the other end of the furnace feeding roller way is communicated with a discharge hole of the heat preservation bin; a smoke exhaust pipe is arranged on the second end face of the heating furnace body; a heat preservation bin is arranged at the feeding end of a furnace entering roller way, a circulating tube nest is embedded in a flue tube bank of a heating furnace, the circulating tube nest is communicated with a circulating oil storage tank pipeline, tail gas with the temperature of about 900 DEG C is used for heating circulating oil through heat exchange, and the circulating oil is intr