What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
In the riveting operation, the rivet used is composed of a mandrel and a deformed collar. When in use, a through hole is drilled on the two components to be connected, and then the head of the rivet is passed through the through hole and clamped by a rivet. The tail of the rivet will break the rivet, the head of the rivet and the deformed collar remain in the through hole, and the whole riveting process is completed. The existing pull rivets have the following shortcomings: first, the parts where the pull rivet and the two components are connected cannot be completely and tightly fitted, which meets the requirements of non-sealing for parts that have waterproof and leak-proof requirements; second, the existing pull rivets The separation groove of the rivet mandrel is close to its head. When the mandrel is broken by the rivet during the riveting process, basically only the head of the mandrel remains in the deformation collar, and the connection of the two components depends on the deformation of the collar. Under the action of compressive stress, the inside of the deformed collar becomes hollow due to the breaking of the mandrel, and cannot bear large shear stress.
1. The expansion phenomenon of the spring washer is generally not the problem of the spring washer itself. 2. The spring washer with the expansion ring must be subjected to a radial external tension. The external tension is derived from the tightening axial force generated by the tightening torque. The chamfer creates a radial component of the axial clamping force, which expands the opening of the spring washer. The smaller the chamfer diameter, the greater the possibility of ring expansion. 4. Adding a flat washer between the nut and the spring washer helps to slow down or prevent the expansion of the ring, but the flat washer is too thin or too soft. Prevent ring expansion 5. The reason for the hydrogen embrittlement fracture of spring washers is generally due to unreasonable heat treatment process and the failure of hydrogen removal treatment after electro-galvanizing. A large number of tests and long-term practical experience have confirmed the above analysis.
At present, in the production workshop, there is no special tool for removing rivets such as skew, wrong rivets, and multiple rivets. When removing these rivets, workers use homemade rivet removal tools, use a sledgehammer to remove the rivet head, and then use a sharp tool to remove the rivet rod. eject. During the removal operation, sometimes the rivet head will fly out, the speed is high, the danger is extremely high, and the labor intensity is high, which has caused many industrial accidents.
Large, countersunk, and thin rivet nuts can be produced according to different die angles. Then the cold forged rivet nut is degreasing, cleaned and annealed, and then extruded and tapped and surface electroplated. Since the rivet nut is formed by cold extrusion of low carbon steel, it has high mechanical properties. Specifically, the tensile strength of M3 is 250Kg, the shear strength is 140Kg; the tensile strength of M4 is 700Kg, the shear strength is 220Kg; the tensile strength of M5 1100Kg, shear force 380Kg; M6 tensile force 1750Kg, shear force 450Kg; M8 tensile force 2650Kg, shear force 660Kg.
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