What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Currently, a screw generally includes a shank body, a threaded portion formed on the outer edge of the shank body, and a conical head formed at the rear end of the shank body. When the current thread is in use, since the thread part is cylindrical, the thread part and the workpiece are vertical, so it is relatively laborious when in use, and it is difficult to locate, lock and unlock.
Generally, the countersunk head is used in places where the surface is required to be smooth without protrusions, because the countersunk head can be screwed into the part. Round heads can also be screwed into parts. The tightening force of the square head can be larger, but the size is large. In addition, in order to meet the needs of locking after installation, there are holes in the head and holes in the rod. These holes can prevent the bolts from loosening when they are vibrated. Some bolts without threads should be made thin, called thin-waisted bolts. This kind of bolt is beneficial to the connection under variable force. There are special high-strength bolts on the steel structure, the head will be larger, and the size will also change. In addition, there are special uses: for T-slot bolts, which are most used on machine tool fixtures, with special shapes, and both sides of the head should be cut off. Anchor bolts, used for machine and ground connection and fixing, come in many shapes. U-bolts, as previously described. and many more. There are also special studs for welding. One end has a thread and the other end is not. It can be welded to the part, and the other side can directly screw the nut.
An elastic cylindrical pin loading and unloading tool, comprising a rectangular base on which a hollow cylindrical tooling station is arranged for fixing a tooling and installing a cylindrical pin on the tooling for shear force testing, the The tooling includes an outer cylinder and an inner cylinder that are assembled together, the outer cylinder and the inner cylinder are in clearance fit, and the base is further provided with a counterbore for taking out the inner cylinder after the tooling test is completed.
Currently, the method of fixing objects on cement is with cement nails or expansion screws. Cement nails are objects made of hard alloy steel that look like iron nails, which are composed of nail tips and nail bodies. Cement nails are hammered into the cement. Cement nails are easy to drive in, but not removable. The expansion screw is composed of a large end screw, a slotted sleeve, a gasket, a spring washer, and a nut. When using, first drill a hole in the cement with an electric hammer, put in the expansion screw, and tighten the nut to make the slotted sleeve expand at the tail of the big tail screw, so as to fix the expansion screw on the cement. At this time, unscrew the nut to install a fixed object on the expansion screw. Although this method can be disassembled, an electric hammer is required for the first installation, which is inconvenient.
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