Anchor bolts can be divided into fixed anchor bolts, movable anchor bolts, expansion anchor anchor bolts and adhesive anchor bolts. According to the different shapes, it is divided into: L-shaped embedded bolts, 9-shaped embedded bolts, U-shaped embedded bolts, welded embedded bolts, and bottom plate embedded bolts.
The profile of the American National thread (60 profile angle and H/8 flatness) is different from the Wyeth thread profile (55 profile angle and H/6 flattening height). American National Thread is widely used in regions and industries that are influenced by American industry. In World War II, due to the inconsistent thread standards used by the Allies, the logistical supply difficulties caused serious economic losses and casualties to the Allies. Immediately after the end of World War II, the United States, the United Kingdom, Canada and other allies immediately began to formulate a unified thread standard among allied countries, and promulgated a unified thread standard in 1948. Because the economic strength and military strength of the United States dominated the Allied forces at that time, the unified thread was mainly formulated according to the national thread standard of the United States. Unity; the latter letter N is derived from the N designation for American National Threads. Since then, the unified thread began to squeeze the original use market of the British Whitworth thread.
At the beginning of the quality inspection process broadcast, we ordered the cross recessed screw and screw wire material into our production screw industry. For manufacturers in the screw industry, we must first detect the wire diameter of the screw wire and the material of the screw. Generally, the wire diameter of the screw is measured by a caliper and a measuring wire. Diameter size, whether it is the same as the size ordered by yourself. After testing these, it is the testing in the production process, starting from the head of the screw, to determine the size of the head, the opposite side of the head, the diagonal angle, the depth of the cross groove, the tolerance range of the screw, and so on. These are checked with calipers. In the inspection of all aspects when rolling teeth, the main thing is whether the thread can pass the pass and stop gauge, and whether the screw thread can pass the gauge and stop. Next is the electroplating measurement problem. After electroplating, whether it meets the requirements of environmental protection and whether it can pass the time required by the salt spray. Tools include environmental testing machines and salt spray testing machines. In short, in the production and sales process of cross recessed screws, there must be necessary tools to detect the quality of screws. The summary should be summarized as follows: calipers, hardness testers, salt spray machines, environmental testing machines, pass and stop gauges, etc. .
The screw refers to the screw (foreign name: Screw), which is a tool that uses the physical and mathematical principles of the oblique circular rotation of the object and the frictional force to gradually fasten the utensils and parts. A screw is a common term for fasteners, an everyday colloquial language. Metric threads are measured in MM (millimeters) and have a cusp angle of 60 degrees. Both US and Imperial threads are measured in inches. The cusp angle of the American thread is also 60 degrees, while the cusp angle of the imperial thread is 55 degrees.
Standard parts are commonly used parts, which are widely used in various mechanical structures. Among them, the T-track bolt is a common standard part. The existing T-shaped track bolts, especially those used in high-speed railways, are often installed in pre-buried tracks, and the T-shaped track bolts are not easy to install, which may easily cause positional deviation.
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