Countersunk flat head screw, cross recessed bolt, step screw, stainless steel 304

Spring mattresses and spring seat cushions are commonly used and high-performance furniture items in modern times, and their cushion cores are composed of springs. It fully utilizes the advantages of good spring elasticity, good support, strong breathability, and durability. Traditional spring mattresses are made by connecting thick coils of springs with steel wires, which have a high hardness. The resulting mattress has a strong sleeping sensation and good support, but its elasticity is not obvious and it is easy to be pulled. Most of the older generation often use a connected spring bed, but if they sleep in a fixed position for a long time, sit by the bedside and corners, or flip the mattress irregularly, it can easily become concave and elastic fatigue.

The process of removing iron oxide plates from cold heading steel wire rods involves stripping and dephosphorization, which can be achieved through two methods: mechanical dephosphorization and chemical pickling. Replacing the chemical pickling process of wire rods with mechanical phosphorus removal not only improves productivity but also reduces environmental pollution. This phosphorus removal process includes bending method (commonly using circular wheels with triangular grooves to repeatedly bend wire rods), spray nine method, etc. The phosphorus removal effect is good, but it cannot remove residual iron and phosphorus (the removal rate of oxide scale is 97%), especially when the adhesion of oxide scale is strong. Therefore, mechanical phosphorus removal is affected by the thickness, structure, and stress state of the iron sheet, and is used for low strength fasteners (less than or equal to grade 6.8) made of carbon steel wire rods. High strength bolts (greater than or equal to grade 8.8) are treated with wire rods after mechanical phosphorus removal to remove all oxide scales, and then undergo a chemical acid washing process to achieve composite phosphorus removal. For low-carbon steel wire rods, the residual iron sheet from mechanical phosphorus removal can easily cause uneven wear and tear during grain drawing. When the grain drawing hole adheres to the iron sheet due to the friction of the wire rod at external temperature, longitudinal grain marks are generated on the surface of the wire rod. When the wire rod is cold upset with flange bolts or cylindrical head screws, micro cracks appear on the head, and more than 95% of them are caused by scratches on the wire surface during the drawing process. Therefore, the mechanical phosphorus removal method is not suitable for high-speed drawing.

Screw, also known as "Screw" (screw) or "screw" (screw rod). In fact, screws are a general term, while screws and screw rods are different from each other. Screws are generally called wooden screws; It is the type with a pointed front end and a larger pitch, commonly used for fastening wooden and plastic parts. A screw rod is a machine screw (mechanical screw) with a flat front end, a small and uniform pitch, and is generally used to fasten metal and machine components.

"A: Metric screw B: American screw C: English screw
A: Metric mechanical screws: Metric
Ex: M3 x 6-P P P B: M3 mechanical screw, 6mm long, cross shaped, round flat head, black plated
Finish Code: Appearance Treatment Specification
Head Code: Head shape.
Screw head shape. Cylindrical head. Half countersunk head. Sink head. Spherical cylindrical head. Pan head. Half round head. Hexagonal head"