What are the requirements for springs in the hardware mold industry?
1. Cold extrusion die
Cold extrusion is divided into forward extrusion, reverse extrusion and compound extrusion. The cold extrusion punch bears a large dynamic load. In order to prevent early fatigue failure of the die, excessive stress concentration should be avoided, and attention should be paid to the punch Stability, the length-to-diameter ratio (L:D) of the punch should not be too large, when extruding steel parts, L:D≤3:1, extruding copper and its alloy L:D≤5:1, extruding aluminum and The alloy L:D≤10:1. When the stress of the die exceeds σ0.2/2 of the material, the die needs to add a prestressed ring, and the taper (0.5°~1°) can be used between the die and the prestressed ring. ) Fit or hot press fit (red sleeve). Hardware spring
The cold extrusion die of low and medium carbon steel requires high hardness (59~66HRC), high compressive yield strength and appropriate toughness. Commonly used die materials include Cr12MoV, Cr12Mo1V1, W6Mo5Cr4V2 steel and base steel, etc., internal prestress The ring is usually made of 4Cr5MoVSi, 4Cr5MoV1Si steel (46~48HRC), and the outer prestressed ring is usually made of 4Cr5MoVSi, 5CrNiMo and other steels.
2. Cold heading mold
Cold heading is a cold forging process, which relies on the upsetting die to process part of the blank metal into a specific cross-sectional shape under one or more impacts. The blank is mainly wire or bar. Cold heading is widely used in the production of fastening Parts, such as screws and rivets. Materials suitable for cold heading include low-carbon steel wire or bar (75~78HRB), copper and copper alloys, aluminum and aluminum alloys, stainless steel and medium-carbon steel wires with a carbon content of less than 0.44% ( Spheroidizing annealing). The cold heading mold is divided into a punch (or hammer) and a concave mold. The concave mold is divided into an integral concave mold and an open concave mold. The overall concave mold can be made of one material or two Two kinds of materials, the center cavity part is made of different materials to make the concave mold insert. The open concave mold is composed of two modules with grooves on the surface, and the two modules are combined to form a cavity. Slots on different surfaces of the module, and then Multiple new slots can be formed by turning the module.
The surface of the cold heading mold requires high hardness (≥60HRC), and the cold heading mold of hard materials should be hardened as a whole to prevent collapse; under the premise of ensuring no collapse, in order to make the mold have sufficient toughness and prevent cracking, cold heading The hardness of the core of the mold is preferably 40~50HRC.
Commonly used cold heading die steels are T10A, 9SiCr, 9Cr2, Cr12MoV, etc., and the concave mold inserts can be made of Cr12MoV, W6Mo5Cr4V2, WC (containing 13%~25% Co), W18Cr4V steel, and punches with complex shapes and large impact can be used. Impact resistant steel 5CrW2Si, 60Si2Mn and base steel.
3. Aluminum alloy cold extrusion die can be made of T7A, T10A, Cr12, Cr12MoV, GCr15, 9SiCr and CrWMn steel.
Molds with excellent material, correct structural design, good cold and hot processing, and reasonable heat treatment may still fail early during service due to improper adjustment and use of the machine tool. Machine adjustment and operating factors include the accuracy, rigidity, clearance adjustment, and positioning of the machine tool Inaccurate and accidental overload, etc. Taking these factors seriously will help to find the real cause of mold failure. Large fluctuations in mold life in production are often related to machine tool adjustment and use operation factors, and sufficient attention must be paid.