1. What surface defects often occur in automobile springs
(1) Cracks in automobile springs are mainly caused by the material manufacturing process. The cracks extend in the drawing direction, the depth can be from a few millimeters to more than 1 millimeter, and are distributed longitudinally. Cracked materials cannot be used to make springs.
(2) Impurities on oxide scales or material blanks will feel rough and uneven if touched by hand with improper removal of the material surface, sometimes spikes will pierce fingers, and slight oxide scale may not be seen when touched by hand, but the spring rolls in After the spring, you will find that the spring surface is peeled or wrinkled. Materials with serious scaling phenomena cannot be used to make springs. After rolling into the local scaly spring, it must be removed, and slight materials can be removed by shot blasting. For materials with local scale phenomena, unimportant springs can be considered.
(3) Scratches and wire drawing of automobile springs are mainly caused by uneven or poor lubrication of the die holes during the drawing process. The rough surfaces of tools such as rollers, wire guides, and push rods will form a wire on the spring surface when the spring is rolled. The stretching direction of the raw materials is generally distributed. For springs with scratches and drawing depths that do not exceed the specified tolerance of the wire, it is not suitable to manufacture springs with high fatigue performance, such as valve springs, plunger springs, etc.
(4) Most of the pits are impurities or scale attached to the surface of the steel wire during drawing, and then fall off to form pits. For materials with pits in some parts, springs with pits on the surface should be removed after rolling into springs. Materials with a wide range of pits should not be used to make springs.
(5) The cause of the corrosion of automobile springs is the bad corrosion of the materials before leaving the factory, and the other may be caused by improper storage. Slightly rusty materials can be removed by sanding. If there is no obvious corrosion pit, it can be used. If there are corrosion pits, it should not be used to manufacture springs.
(6) Hairline, also known as hairline, has shallow depth and severe cracks. There are filaments on the surface of the material, which can be removed by hand. Hairline materials should not be used to make springs.
(7) This kind of steel wire can be touched by hand, which can obviously feel the uneven thickness, similar to a bamboo joint. Most of these defects are generated during the wire drawing process, of which thin steel wire is the most common. The spring wire affects the technological performance of the coil spring, resulting in unstable control of the inner and outer diameters of the coil spring and affecting the spring load. Therefore, for springs with high inner and outer diameters and load requirements, bamboo wire cannot be used. Springs with lower inner and outer diameter requirements and no load requirements can be considered.