The production process of the screw is divided into 7 steps, namely, annealing, pickling, drawing, forming, rolling, heat treatment grade surface treatment.
Annealing process: The first processed product is placed in a furnace and then closed with a furnace lid. One furnace can handle 8.4 tons at the same time. Then slowly raise the temperature to the specified temperature, this step takes 3-4 hours. Then take the temperature slowly to 550 degrees for 3-4 hours and allow the product to cool naturally to room temperature. This process can adjust the crystalline structure, reduce the hardness and improve the normal temperature processing of the wire.
Pickling process: The purpose of the acid wash is to remove the oxide film from the wire. Now the entire disk is invaded at room temperature and the three hydrochloric acid tanks with a concentration of 20-35 minutes are used. Then use clear water to clarify the hydrochloric acid corrosion on the surface of the wire. In order to make the film produced in one process more compact, oxalic acid is used to increase the activity of the metal. The disc was infiltrated with phosphate, and the surface of the steel was contacted with a chemical conversion treatment solution. The treatment solution and steel were dissolved to form a compound, which was attached to the screw surface to form a film. Then use clean water to remove the surface residue. Then use the lubricating oil to increase its lubricity.
Drawing line process: Use the fine drawing and rough drawing of some products to pull the plate element to the required wire diameter. This procedure is applicable to the wires used in large screws, nuts, and tooth bars.
Forming process: There are two types of hexagon bolts: one is four-mode four-stroke or three-mode three-stroke, but three-mode three-stroke. The screw is a two punch. Then hot, hot is divided into three steps, the first step in the product into the heating device according to product specifications set the heating time and temperature. In the second step, after heating, the product is moved into a mold for molding. Then use a beamer to squeeze it down.
Milling process: The semi-finished product that has been formed is screwed or tapped to the required thread.
Heat treatment process: In order to improve the mechanical properties of the material, eliminate residual stress and improve the metal cutting process requires the heat treatment of the product. According to the needs of the product, you can use both pre-heat treatment and final treatment.
Surface treatment process: Through electroplating, hot-invasion galvanization, mechanical galvanization to form a coating on the surface of the product, so that the product surface appearance, anti-corrosion effect.