What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Pedicle screws can be divided into four types: one-way short-tail screw, one-way long-tail screw, universal short-tail screw and universal long-tail screw. Pedicle screws can effectively complete the three-column fixation of the spine and are clinical The most widely used internal fixation method for the treatment of spine-related diseases. Due to the different types of pedicle screws, four different screwdrivers are required to complete the screw insertion. However, the implantation of pedicle screws is performed in a complex three-dimensional space, which has high difficulty and risk. Mis-implantation of screws may cause instability of the internal fixation frame in the early stage, and may cause false joint formation in the later stage. Therefore, in the process of spinal internal fixation, it is necessary to ensure the accurate implantation of pedicle screws is the key to the success of the entire spinal internal fixation, and the selected implanted instruments are particularly important.
For hexagonal nuts, the commonly used standards are: GB52, GB6170, GB6172 and DIN934. The main differences between them are: the thickness of GB6170 is thicker than that of GB52, GB6172 and DIN934, commonly known as thick nuts. The other is the difference between the opposite sides, the opposite sides of DIN934, GB6170 and GB6172 in the M8 nut series are 13MM smaller than the opposite side 14MM of GB52, and the opposite sides of M10 nuts, DIN934 and GB52 are 17MM. The opposite side of GB6170 and GB6172 should be 1MM larger, M12 nut, DIN934, GB52's opposite side is 19MM larger than GB6170 and GB6172's opposite side 18MM is 1MM larger. For M14 nuts, the opposite side of DIN934 and GB52 is 22MM, which is 1MM larger than the opposite side of GB6170 and GB6172, which is 21MM. The other is the M22 nut. The opposite side of DIN934 and GB52 is 32MM, which is 2MM smaller than the opposite side of GB6170 and GB6172, which is 34MM. (Besides the thickness of GB6170 and GB6172 are the same, the width of the opposite side is exactly the same) The rest of the specifications can be used in general without considering the thickness.
Countersunk rivet is a kind of part that uses its own deformation or interference connection to connect and position two objects in riveting. It is widely used in automobiles, vehicles, electromechanical products, aerospace products and other fields. When the countersunk head rivet is used, the head of the rivet sinks into the connected parts in whole or in part. This structure is mostly used for parts that require a smooth and smooth appearance. The standard structure of countersunk head rivets is specified in the national aviation standard, national standard and national standard, and the countersunk head rivets involved in these standards are all standard rotary structures.
Bolts refer specifically to screws with larger diameters and may also have no heads, such as stud bolts. In general, it is not called a stud bolt but a stud stud. The most common form of stud is threaded at both ends and a polished rod in the middle. The most typical use: anchor bolts, or places similar to anchor bolts, thicker connections, when ordinary bolts cannot be used.
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