By the end of the 1920s, with the expansion of the market and new applications, the new design was emphasized, and its application performance was widely improved. Next, Jinmeizi introduced the four different stages of the development of self-tapping screws in 40 years. Forming self-tapping screws, thread cutting self-tapping screws, thread rolling self-tapping screws and self-drilling self-tapping screws.
1.Ordinary self-tapping screws
Ordinary self-tapping screws are a direct product of early thin-tipped metal screws. The principle is that when it is screwed into a pre-made hole, it is formed by the displacement of the material close to the hole, and the material is pushed into the space before the thread. The internal thread connected to the screw.
2.Self-cutting and self-tapping screws
Since the thread forming of ordinary self-tapping screws can only be easily realized on materials that are relatively thin and have good toughness, the development of self-tapping screws has been expanded to thicker sections and harder, more brittle and other materials with poor deformation ability. In this way, a self-cutting and self-tapping screw has been developed, and a cutting groove or cutting edge is machined at the end of the screw rod. When the screw is screwed into a pre-made hole, the screw plays the role of silk. Self-connected thread.
3. Self-extruding and self-tapping screws. In the 1950s, screw fastener engineers began to realize the potential advantages of self-tapping screws with "structural" rather than just attachments that bear light loads. This led to the development of a kind of New self-tapping screws-thread rolling self-tapping screws (self-extruding self-tapping screws). According to the design principle of cold forged taps, people have specially designed threads and ends for this type of screw, so that the screw can pass through the thread of its thread. On top, not on the sides of the entire thread. Intermittent, cyclic pressure is applied to form the internal thread of the connection by focusing and limiting forming pressure. Make the pressed material close to the hole easier to flow and better fill the flanks and bottoms of the self-tapping screw threads. Because the frictional resistance is much lower than ordinary self-tapping screws. Therefore, thread-rolled self-tapping screws (self-extruding self-tapping screws) can be screwed into thicker sections. At the same time, it has better screw-in control and tightening torque, and greatly improves the connection strength and overall firmness. The engineering standards for such self-tapping screws stipulate the choice of materials, and the heat treatment mechanical properties and work performance must be strictly controlled. These requirements far exceed the corresponding requirements for ordinary self-tapping screws and self-cutting self-tapping screws. Therefore, c, self-extrusion Self-tapping screws (thread-rolled self-tapping screws) are indeed one: structural "fasteners."
4.Self-drilling and self-tapping screws
People have done statistics. Among the several costs that constitute the total assembly cost, the highest includes hole processing. In actual applications, self-tapping screws need to process prefabricated holes, and in order to make prefabricated holes play a good role in practical applications As a result, the size of these holes must be controlled within a fairly strict range. In the early 1960s, self-drilling and self-tapping screws appeared. Since there is no need to process prefabricated holes, a major step forward has been taken to reduce low assembly costs. In a nutshell, self-drilling and self-tapping screws realize one operation of drilling, tapping and tightening.
Self Tapping Screw
5.Other self tapping screws
In the four main stages of the design and development of self-tapping screws, two other newly developed products are also worth introducing. Two are screws with a special thread form. One is used for plastic and other low strength materials. One is used in the construction industry to connect cement concrete panels, also known as wall panel self-tapping screws.
With the development of the times and the continuous improvement of human technology, many self-tapping screws can be used better and achieve a higher tightening effect. So far, great improvements have been made. According to the needs of different enterprises, different specifications and threaded self-tapping screws can be customized. It also emphasizes the application performance of self-tapping screws.
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