1、 What are the stress relief annealing equipment?
(1) Continuous hot air tempering electric furnace. The electric furnace is widely used in the spring manufacturing industry in recent years. Its advantage is that it can accurately control the temperature and time and save power. If the electric furnace is arranged in front of the coil spring machine, the automatic production line of coil spring and stress relief annealing can be realized.
(2) Hot air circulating tempering electric furnace and box type electric furnace. The furnace temperature is relatively uniform, but the holding time is much longer than that of the nitrate furnace.
(3) Nitrate tempering furnace. The furnace is generally manufactured by the spring manufacturer. The advantages of nitrate furnace are fast heating speed and shorter holding time than other furnaces. The disadvantage is that the temperature is not uniform, and the liquid in the furnace tends to invade the spring surface, which is especially unfavorable to the oil quenched and tempered spring steel wire. The springs treated by the nitrate furnace shall be cleaned by water cooling, and then immersed in antirust water for several minutes to prevent rusting. When electric furnace is used for stress relief annealing, the holding time shall be appropriately longer than that of nitrate furnace. The springs shall be arranged neatly when heated in the furnace. The springs with special shape or easily deformed shall be equipped with corresponding auxiliary tools.
2、 What is the purpose of stress relief annealing?
(1) Eliminate the internal stress of wire cold drawing and spring cold coil forming;
(2) To stabilize the spring size, the spring without stress relief annealing will cause the outer diameter increase and size instability in the subsequent process processing and use;
(3) Improve the tensile strength and elastic limit of the wire;
(4) The spring size is controlled by stress relief annealing. If the spring is installed on the fixture for stress relief annealing, it can adjust the height of the spring
