As One Of The Essential Parts Of Daily Life, How Are Screws Made?

The screw production process is divided into 7 steps, respectively, annealing, pickling, drawing, molding, grinding, heat treatment grade surface treatment.

 

Annealing process: the first treated product is placed in the furnace and then closed with the furnace cover. One furnace can process 8.4 tons at a time. Then slowly increase the temperature to the specified temperature, this step takes 3-4 hours. The temperature is then slowly reduced to 550 degrees for 3-4 hours, allowing the product to cool naturally to room temperature. This process can adjust the crystalline structure, reduce the hardness, improve the normal temperature workability of the wire.

 

Pickling process: The purpose of acid washing is to remove the oxide film of the wire, and the whole disk is now invaded into three salt tanks at normal temperature with a concentration of 20-35 for a few minutes. Then clear the hydrochloric acid corrosion on the surface of the wire with water. In order to make the skin film produced in the following process more compact, oxalic acid is used to increase the activity of the metal. After the disc is penetrated into phosphate, the steel surface is in contact with the formation liquid, so that the treatment liquid and the steel dissolve to form a compound, which is attached to the screw surface to form a skin film. Then use clean water to remove the surface residue. Then use lubricating oil to increase its lubricity.

 

Drawing process: Use fine drawing and coarse drawing for some products to cold draw the disk element to the required wire diameter. This process is suitable for large screws, nuts, thread used.

 

Forming process: There are two kinds of forming of hexagonal bolts: one is four die four punch or three die three punch, but three die three punch. The screws are two strokes in one die. The heat score is divided into three steps. The first step is to put the product into the heating equipment and set the heating time and temperature according to the product specifications. The second step, after heating, the product is moved to the molding machine to mold it. Then it is squeezed by a beam machine to shrink the rod.

 

Grinding process: By grinding or tapping the semi-finished product has been formed to the required thread.

 

Heat treatment process: In order to improve the mechanical properties of the material, eliminate residual stress and improve the machinability of the metal require heat treatment of the product. According to the needs of the product, two ways can be selected: preliminary heat treatment and final treatment.

 

Surface treatment process: through electroplating, hot dip galvanizing, mechanical galvanizing to form a covering layer on the surface of the product, so that the product surface beautiful, anti-corrosion effect.