Service HotlineEach self-tapping screw is composed of three parts: the head, the shank and the end of the shank. The composition of each self-tapping screw has four major elements: head shape, wrenching method, thread type, and end form. 1. Head Shapes There are various head shapes. There are round head (semi-round head), flat round head, round head flange (with pad), flat round head flange (with pad), pan head, pan head flange (with pad), countersunk head, semi-countersunk head, Cylinder head, spherical cylinder head, horn head, hexagonal head, hexagonal flange head, hexagonal flange (with pad) head, etc. 2. Wrenching method The wrenching method refers to the way of twisting the head of the screw when installing and tightening the screw. There are two basic methods: external wrench and internal wrench. Generally speaking, external wrenching will allow more torque than any form of internal wrench (internal groove). External wrench: hexagon, hexagonal flange surface, hexagonal flange, hexagonal flower shape, etc.; internal wrench: flat groove, cross groove H type, cross groove Z type, cross groove F type, square groove, compound groove, inner flower Key, inner hexagon flower, inner triangle, inner hexagon, inner 12 corner, clutch slot, six-blade slot, high torque cross slot, etc. 3. There are many types of threads, including self-tapping threads (wide thread), machine threads (ordinary threads), drywall screw threads, fiberboard screw threads, and some other special threads. In addition, threads can be divided into single-lead (single-end), double-lead (double-end), multi-lead (multiple-end) and high-low thread double-end threads. 4. Terminal form There are two main types of terminal form: tapered end and flat end. However, according to the needs of use, at the screw-in part of the end, grooves, grooves, incisions or parts with a similar drill shape can be processed with cutting function. In some standards, it is also a tapered end or a flat end, and there are different forms such as a rounded end.
However, although the above-mentioned screw belt (2) can achieve the expected effect, it is also found in its actual implementation. Although this structure has multiple grooves on both sides of the main body for the driving and turning of the locking screw tool, However, the groove is only used for driving the screw belt drive, and since the screw will swing on the screw belt, it is impossible to stably align the screw on the screw belt with the point where the screw is to be set. , which leads to great inconvenience in operation and use, and also affects the efficiency of screw and screw installation, so that there is still room for improvement in the overall structural composition.
The material of the round head three combination screw is divided into iron and stainless steel. The iron ones are made of different iron screw wires. Generally, the wire of the combination screw is 1010, 1018, 10B21 and so on. 10B21 is used to make 8.8 grade combination screws. Like 8.8-grade socket head cap screws, 10B21 wires are often used to make them. When done, go to heat treatment. After heat treatment, remove hydrogen and electroplating. This is to prevent the spring washer of the socket head cap screw from breaking. Stainless steel combination screws, in the combination screw market, generally refer to stainless steel SUS304 combination screws. 201 combination screws generally do very little. Few manufacturers of round head three combination screws produce 201 combination screws. Because the hardness of the screw wire of stainless steel 201 is not well controlled, it is easy to produce cracks. Introduction to the basic knowledge of electroplating round head combination screw electroplating generally refers to the de-plating of iron combination screws. Electroplating is divided into environmental protection and non-environmental protection. Commonly used combination screw electroplating colors include green color zinc, green blue zinc, green white zinc, green nickel, red color, white zinc, white nickel, etc. Cross recessed combination screws, hexagon combination bolts and self-tapping combination screws are used in the same way as the corresponding cross recessed screws, hexagon head bolts and self-tapping screws. The main feature of these combination screws is that they are equipped with corresponding washers, which are very convenient to use.
Usually, the car wheel is fixed on the axle sleeve with positioning pins and pins, and the tire hub and the sleeve are fastened on the axle with locking nuts, lock washers, and adjusting nuts. This structure can operate normally within a certain period of time when the vehicle speed is low and the vibration is small. However, when the car runs for a long time, especially when the road surface is uneven and the load changes sharply, the axle sleeve bears a great impact. Once the shear force generated is too large, the pin will break, and the nut will be loosened. Affected, the wheel and hub will be loose. If the maintenance is not timely, or the driver is inexperienced, the car will have an accident in which the tire falls off with the wheel hub. This is extremely dangerous. So people are looking for ways to prevent wheels and hubs from falling off
The process factors that affect the quality of high-strength fasteners include steel design, spheroidizing annealing, peeling and dephosphorization, drawing, cold heading, thread processing, heat treatment, etc., and sometimes the superposition of various factors.
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