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Fastener High Productivity
Jul 10, 2017

Fastener products include bolts, Fastener screws, studs or nuts, washers, etc., Fastener part of the choice of black process, both to meet the appearance of fasteners, rust requirements, and low cost, Fastener high production efficiency; So that can reduce the quenching stress, Fastener so that fasteners in the stress conditions are not easy to break. Black technology is simple, but still have technical content

The fastener to be black-processed was heated and oxidized in sodium hydroxide (NaOH) and sodium nitrite (NaNO2) oxidizing agent in solution tank (145 ± 5 ° C) to form a layer of metal fastener Magnetic iron oxide (Fe3O4) film, Fastener the thickness is generally 0.6 ~ 0.8μm was black or blue-black.

The most important meaning of fastener hardness is resistance to friction during assembly and / or in mechanical applications. For thread forming and thread cutting tapping screws, Fastener since it uses extruded or tapped from the mating holes With the internal thread,Fastener so it is clear that its hardness must be higher than the hardness of the assembly. If this is not the case, Fastener then the assembly of the tapping thread will be deformed or damaged, and lead to spin does not go in. Two different hardness Of the material can be clearly divided, such as clay and steel, if you want to wire the tapping screw into the clay, Fastener because the clay is soft and easy to deformation, of course, very easy to spin into the Down, if you want to do the thread to do the screw thread tapping screws screwed into the steel, Fastener so the thread forming tapping screws must be harder than with the workpiece.

In some cases, the fasteners will also be used to bear the face, especially some of the screws with the shoulder, the hardness is only a few important bearing parts work but it is very important to these bearing surface must have sufficient hardness Take on the rapid increase in assembly and will accumulate the excess friction to ensure the function of the assembly and reduce the amount of maintenance.When we take clay and steel as an example, because the steel is harder than clay, so as the moving fastener steel than Clay used for a long time

By grinding the rivet head, use a grinder, Fastener a punch and a different grade of drill to remove the rivet. Grind the rivet head as much as possible during the grinding process (Figure 1), and pay attention to control the grinding attitude and the amount of grinding, Fastener can not damage the surrounding rivets and structural parts surface. Fastener Using the punch and the hammer in the polished surface has been polished to play the punch point (Figure 2), Fastener the main role is to break the direction of the drill when the direction of guidance. Select the drill bit to be smaller than the diameter of the rivet and drill a part of the remaining rivet pin (Figure 3) to ensure that the drilled hole is completely centered on the rivet rod so that the drilled hole does not expand But also for the next level of drilling to provide a guiding role. Fastener And finally replaced with a rivet diameter of a drill bit carefully drilled rivet rod

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