Service HotlineThe first person to describe the spiral was the Greek scientist Archimedes (c. 287 BC - 212 BC). An Archimedes screw is a huge spiral contained in a wooden cylinder that is used to irrigate fields by raising water from one level to another. The real inventor may not be Archimedes himself. Maybe he was just describing something that already existed. It may have been designed by the skilled craftsmen of ancient Egypt for irrigation on both sides of the Nile. In the Middle Ages, carpenters used wooden or metal nails to attach furniture to wooden structures. In the 16th century, nail makers began producing nails with a helical thread, which were used to connect things more securely. That's a small step from these kinds of nails to screws. Around 1550 AD, the metal nuts and bolts that first appeared in Europe as fasteners were all made by hand on a simple wooden lathe. Screwdrivers (screw chisels) appeared in London around 1780. Carpenters have found that tightening a screw with a screwdriver holds things in place better than hitting with a hammer, especially with fine-grained screws. In 1797, Maudsley invented the all-metal precision screw lathe in London. The following year, Wilkinson built a nut and bolt making machine in the United States. Both machines produce universal nuts and bolts. Screws were quite popular as fixings because an inexpensive method of production had been found at that time. In 1836, Henry M. Philips applied for a patent for a screw with a cross recessed head, which marked a major advance in screw base technology. Unlike traditional slotted head screws, Phillips head screws have the edge of the head of the Phillips head screw. This design makes the screwdriver self-centered and not easy to slip out, so it is very popular. Universal nuts and bolts can connect metal parts together, so by the 19th century, the wood used to make machines to build houses could be replaced by metal bolts and nuts. Now the function of the screw is mainly to connect the two workpieces together and play the role of fastening. The screw is used in general equipment, such as mobile phones, computers, automobiles, bicycles, various machine tools and equipment, and almost all machines. need to use screws. Screws are indispensable industrial necessities in daily life: extremely small screws used in cameras, glasses, clocks, electronics, etc.; general screws for televisions, electrical products, musical instruments, furniture, etc.
A rivet is a part that uses its own deformation or interference to connect the riveted parts in riveting. With the continuous progress and development of science, rivets have been used in many occasions because of their convenient use and reliable connection. The rivet includes a nail head and a stem. The traditional processing mold for the rivet head includes a base, and a nail head forming part is arranged on the base. However, due to the limited service life of the mold, the processing mold of this structure is replaced. It needs to be replaced together with the base, which is a waste of material, which increases the production cost, and the rivet itself is relatively cheap, so this reduces the profit of the enterprise.
Self-tapping screws were introduced into the industry in large numbers in 1914. The earliest design (essentially imitating a wood screw) was a thread-forming screw made of hardened steel with an A-ended end, mainly used to connect sheet metal channels for heating and ventilation systems. Therefore, it is also called: sheet metal screw. By the end of the 1920s, with the widening of the market and new applications, emphasizing new designs, its application performance was widely improved. The following introduces the four different stages of the development of self-tapping screws in 40 years: thread 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 (thread forming self-tapping screws) Ordinary self-tapping screws are a direct product of early sheet metal screws. The principle is: when screwing it into a prefabricated hole, the internal thread connected to the screw is formed by the displacement of the material around the hole and the material is pushed into the space between the threads. 2. Self-cutting self-tapping screws (thread cutting self-tapping screws) Because ordinary self-tapping screws are formed only in very thin threads. And it can be easily realized on materials with good toughness. Develop and expand the use of self-tapping screws to thicker sections and harder, brittle and other materials with poor deformability. In this way, the self-cutting self-tapping screw is developed: a cutting groove or cutting edge is machined at the end of the screw shank. When this kind of screw is screwed into the prefabricated hole, the screw acts as a tap and actually cuts out the thread that connects with itself. 3. Self-Extrusion Self-Tapping Screws (Thread Rolled Self-Tapping Screws) In the early 1950s, fastener engineers began to recognize the potential advantages of self-tapping screws as structural rather than just lightly loaded attachments. This has led to the development of a new self-tapping screw thread rolling self-tapping screw (self-extrusion self-tapping screw). According to the design principle of cold forging taps, the thread and end are specially designed for this kind of screw, so that the screw can be formed by applying intermittent and periodic pressure on the crest of its thread instead of on the side of the entire thread. Internal thread for connection. By concentrating and limiting the forming pressure, the pressurized material next to the hole is made to flow more easily and to better fill (squeeze) into the flanks and roots of the thread of the self-tapping screw. Since the frictional resistance of screwing in is much lower than that of ordinary self-tapping screws, threaded rolling self-tapping screws (self-extrusion self-tapping screws) can be screwed into thicker sections. At the same time, it has better screw control and tightening torque, and greatly improves the connection strength and overall firmness. The engineering standard of this kind of self-tapping screw stipulates that the selection of materials, the mechanical properties of heat treatment and the working performance should be strictly controlled. 4. Self-drilling and self-tapping screws (self-drilling screws) People have done statistics: Among the ten expenses that constitute the total assembly cost, the highest one includes the processing of holes. In practical applications of self-tapping screws, prefabricated holes need to be processed. Moreover, in order to make the prefabricated holes have good effect in practical application, the size of these holes must be controlled within a fairly strict range. In the early 1960s, self-drilling and self-tapping screws appeared. A major step forward in reducing assembly costs by eliminating the need to machine prefabricated holes. In general, self-drilling and self-tapping screws realize drilling, tapping and tightening in one operation. These are the four main stages of self-tapping screw design and development. In addition, two newly developed products are also worthy of introduction. Both are screws with a special thread type. One is designed for plastic and other low-strength materials; the other is used in the construction industry to connect cement wall panels, so it is also called wall panel self-tapping screws.
Existing wood screws are composed of a threaded portion with a tapered angle and arranged along a tapered stem and a screw head. The head of the screw can be a countersunk head, hemispherical, or other shapes, and the head of the screw has a groove that fits with the tool, a word groove, and a concave cross groove. The taper angle of existing wood screws is either 45 degrees or 60 degrees, and the front end of the taper angle is a pointed point formed by a rotating thread. The existing wood screws have the following three deficiencies in use. Because the taper angle is 45 degrees or 60 degrees, and the thread angle is 64 degrees, the resistance when entering the material is relatively large, so the existing wood screws are manually screwed. It is difficult to screw in, especially when it is used for hardwood materials, and it often happens that the groove of the screw head is screwed out; A large lateral moment will be formed when the screw is screwed, which is prone to the problem of deviation from the position; in addition, because the existing screw is tapered, it will be subjected to both radial force and axial force when entering the material, and its stress state It is more complicated, so it is easy to cause the cracked wood material to burst, and even cause the material to have longitudinal cracks and be unusable.
drilling and tapping screw, more specifically, refers to a drilling and tapping screw that can be closely connected to an object without clearance. Screws usually use a screw design to achieve the purpose of tightening, or adjusting distance, or moving or transmitting power. Among them, it is the most common for tightening, and the screws generally used for tightening also usually have The combined function of self-drilling, tapping and locking can achieve the purpose of its tight fit. Known drilling and tapping screws are such as
We have many years of experience in the production and sales of screws, nuts, flat washers, etc. The main products are: knurled copper column copper screws and nuts, Q194 small square head bolts, accessories solid wood connection through embedded nuts, round gaskets and other products, we can Provide you with the right fastener solution for you.
