What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
At present, there are mainly the following methods for classifying screws of different lengths mixed together: First, visual identification and manual sorting. This method is time-consuming, labor-intensive and inefficient. Second, the screws are centrifuged and screened according to the quality and size of the screws. However, the quality of screws of the same length is not necessarily the same when the materials of the screws are different. Third, sorting is carried out using a screening device with sieve holes, but the sieve holes are generally simple geometric shapes, which can only roughly distinguish the length of the screws. Moreover, the specific position where the screw falls into the screen hole will also affect the degree of screening. It can be seen that the above-mentioned methods for classifying screws all have the problem of poor effect.
The more complex inlaid embedded copper nut copper insert nut specification is M8, this copper insert nut is embedded in the injection molded part of the car, 5 twill embossing, 4 left twill embossing, 1 right twill embossing Knurling. Since there are multiple rolling patterns, double tool rests + double embossing rests are used, and 5 grooves and 2 chamfers are inserted at one time by a widening forming knife. The hot-pressed copper insert nut contains Reticulated and straight lines, the outer circle is conical, in the process of hot pressing to facilitate smooth introduction into the plastic hole.
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.
Screws can be divided into machine screws, self-tapping screws, drill-tail screws, wallboard screws, fiberboard screws, wood screws, hexagonal wood screws, non-prolapse screws, combination screws, miniature screws, furniture screws, and electronic screws. Divided into 1. Hexagon head (hexagon head) 2. Hexagon head with flange (hexagon head with flange) 3. Square head (square head) 4. T head (hammer head) 5. Oblate head mushroom head ( truss head) 6. cylindrical head (cheese head) 7. round head (round head) 8. pan head (pan head) 9. countersunk head (flat head) 10. raised countersunk head (oval according to the groove type) Can be divided into 1. Philip 2. Ten / one word 3. One word 4. Inner triangle 5. Inner corner square 6. Cross 7. Rice word 8. Flower shape 9. Plum shape 10. Flower shape one word 11. Special shape 12. Inside Hexagon
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