series of nuts are known in the prior art, generally comprising an internal thread which can be threaded onto the external thread of a screw of corresponding design, or a threaded bolt. Nuts of the described type are used, for example, as nuts for fastening screw-like cable connections in conduits of sheet metal housings. Sheet metal housings of this type typically have walls so thin that they cannot be threaded, so a threaded connection of this type is required to complete the installation.
As a special kind of rivet parts, the rivets for shrinking brake pads are used in the accessories of the automobile industry. The original brake pad rivets do not have a chamfered structure, so the materials cannot be normally fed during assembly, or there are burrs, which lead to unqualified batches. When improving this structure, many manufacturers in the same industry often solve the problem by machining chamfering, but for brake pad rivets with thin thickness, it is impossible to achieve the problem of beating and bad material after chamfering processing.
The pretreatment process is a key process that determines the quality of nickel-phosphorus plating on high-strength bolts. The purpose of this process is to remove the passivation layer on the surface of the bolt and prevent the regeneration of the passivation film. The execution of this process directly determines the degree of bonding between the substrate and the coating. Most of the quality accidents in production are caused by poor pretreatment of bolts. Before plating, the oil, rust and oxide scale attached to the surface of the bolt must be carefully removed; the difference with electroplating is that it should be inspected more carefully, and plating is absolutely not allowed on unclean bolts. ① Inspection of bolts: Visual inspection of the surface quality of bolts requires that any burrs left by processing must be removed, and sharp edges and corners must be rounded. ② Manual degreasing; ensure that the surface of the substrate is free of oil stains. ③ Soak and remove oil; boil the bolts in alkaline water to remove the surface oil. ④ Pickling: In order to prevent the alkaline degreasing solution from contaminating the flash nickel plating tank, electro-activation treatment is carried out with pickling solution before flash nickel plating. ⑤ Electro-activation; electro-activation treatment with acid solution. ⑥ Flash nickel plating; flash nickel plating should be used for low alloy steel to increase the bonding strength between the coating and the substrate.
The product structure in the known technology includes a T-shaped bolt with a longitudinal section, and a polygonal nut matched with the bolt. The bolt is divided into two parts: the screw and the screw head. The screw head is placed at one end of the screw to form an integral part. The radial length of the tightening surface of the screw head is greater than the radial length of the screw, and its axial length is less than the axial length of the screw; The solid surface is a polygon, and now a hexagon is commonly used. The periphery of the base of the nut and the screw head has a number of elastic surfaces corresponding to the polygon; the periphery of the axial screw is provided with an external thread matching the internal thread of the nut. In actual use, the fastener of this structure can be tightened by using a conventional screw, such as a wrench. Therefore, its anti-theft performance is poor and it is not suitable for occasions with special requirements.
Now people often use spring washers to lock nuts and bolts, spring washers, generally stainless steel and carbon steel non-closed spiral washers, under the nut, above the flat washer, increase the friction between the nut and the bolt, used to prevent The nut is loose to prevent vibration from loosening
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