The combination screw is actually a kind of screw, but it is special. It is generally a three-component or a two-component, but at least it can be called a combination screw. The main difference from ordinary screws is that they are equipped with one more spring washer or one more flat washer than ordinary screws. This is the main difference between the appearance of combination screws and ordinary screws. In addition to the obvious difference in appearance between combination screws and ordinary screws, the main difference is the difference in mechanical properties and uses. The combination screw is a three-component or two-component with a flat washer. Of course, it is equipped with a flat washer by an ordinary screw. When the spring flat pad is attached, the spring flat pad will not fall off. Fastened to form an assembly. In terms of mechanical performance, the combination screw is composed of three accessories, and in terms of performance, three fasteners must be used together. The mechanical properties of the combined screw are stronger when used. More convenient, the biggest advantage of the combined screw is that the production line can be operated conveniently and quickly, and the work efficiency can be improved. The difference between the use of combination screws and ordinary screws is mainly in the breadth of use. The use of ordinary screws is more extensive than that of combination screws. Basically, ordinary screws are used in industrial products, and combination screws! It is only useful for specific product materials. When the screw needs to be used with a spring washer and a flat washer, the combination screw can be used at this time.
The existing open-type blind rivets are widely used, usually composed of an iron rivet shell and an iron or stainless steel mandrel. During the riveting process, the open-type rivets are often unstable and biased due to the unsteady breaking force of the mandrel. When the foam is riveted, the nail head is directly pulled into the foam layer to damage the product structure. And there may be safety hazards such as scratching the operator during the installation process due to the exposed nail core. At the same time, due to the expansion of the rivet shell hole, the nail head will be loose inside.
The advantage of wood screws is that the consolidation ability is stronger than that of nails, and they can be removed and replaced, which is more convenient to use without damaging the wood surface. This is a kind of nail specially designed for wood, and after entering the wood, it will be embedded in it very firmly. If the wood is not damaged, it is impossible to pull it out, and even if it is pulled out forcibly, it will bring out the nearby wood. Another point to note is that the wood screws must be screwed in with a screwdriver. Never knock them in with a hammer, as it will damage the surrounding wood. A screwdriver is a tool for loading and unloading wood screws. The shape matches the groove shape of the wood screw head, and there are two types: one-word and cross-shaped. In addition, there is a special screwdriver installed on the bow drill, which is suitable for loading and unloading large wood screws. Convenient and labor-saving. [2]
Most of the blind hole installation rivets have the characteristics of light weight, reliable connection, high strength, and convenient and quick installation. For example, blind rivets have been widely used in various aerospace vehicles.
The standard specifies hexagon head bolts with thread specifications of M3~M64, grades A and B. Grade A is used for bolts with D<=24 and L<=10D or L<=150mm (whichever is smaller); grade B is used for bolts D > 24 or L > 10 D or L > 150 (according to the smaller value) bolt size specification mark: thread specification D = M12, nominal length L = 80mm, performance level is 8.8, the table is the same as oxidation, A level Hexagon head bolt tag example bolt GB / T5782-86-M12 × 80 national standard common hex bolt head on the side size and cooperation national standard wrench thread diameter \ pair of edge sidewalls Skin wrench Wrench Double-ended open-end wrench Double-ended Torx wrench. The outer hexagon bolt is the most frequently used type of bolts. The main function of the external thread it has is to cooperate with the nut. Using this threaded connection method, the two parts are integrated. Grade C hexagon bolts are mainly used in steel structure machinery and equipment with relatively rough surface and low precision requirements. Grade A and Grade B hexagon bolts are mainly used in machinery and equipment with smooth surface and high precision requirements. Most of the stainless steel outer hexagon screws are full-tooth and hexagonal head full-tooth bolts. Standard: DIN933, GB5783, ISO4017, ANSIB18. 2.1, JISB1180; non-full thread bolt standards DIN931, GB5782, ISO4014, ANSIB18.2.1, JISB1180.
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