What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Hexagon nuts are divided into three types: I type, II type and thin type according to the nominal thickness. Nuts above grade 8 are divided into two types: type 1 and type II. Type I hexagon nuts are the most widely used. Type 1 nuts are divided into three grades: A, B, and C. Among them, grade A and grade B nuts are suitable for machines, equipment and structures with small surface roughness and high precision requirements. Class C nuts are used on machines, equipment or structures with rough surfaces and low precision requirements.
The purpose of Yueluo is to provide a stamping process for screws. Before stamping, a sticky protective layer is coated on the pressure surface of the screw blank. The sticky protective layer can play a buffering role during stamping and prevent the screw head from being damaged. In order to achieve the above purpose, the technical solution of Yueluo is to design a screw stamping process, which uses a stamping die to stamp the screw blank and punch out the screw head; and before stamping, the pressure surface of the screw blank is coated with adhesive protection. layer.
Some heavy equipment such as large motors, large reducers, etc., in order to facilitate the installation and adjustment of equipment and the need for maintenance space, a certain position needs to be moved during equipment installation and maintenance. Usually, a steel base or platform is set under the equipment, and the base or The platform is provided with an oblong bolt installation slot, commonly known as an oblong slot, as shown in Figure 1--Figure 4. When using common hexagon head bolts or common T-bolts with the long circular groove in Figures 1 and 2, auxiliary fixing bolts or welding stoppers are required on the back of the long circular groove to prevent the bolt from rotating when the nut is tightened. In Fig. 3 and Fig. 4, the long circular groove itself has a clamping groove to prevent the rotation of the bolt, but this structure greatly increases the processing cost of the long circular groove.
spring washer is installed under the nut to prevent the nut from loosening. It is stated in the national standard. Hexagonal slotted nuts are specially designed for use with bolts with holes at the end of the screw, so that the cotter pin can be inserted into the hole of the screw from the groove of the nut to prevent the nut from automatically loosening. It is mainly used for vibration loads or alternating loads. . The methods to prevent the nut (or bolt) from automatically loosening in the mechanical design and production are as follows: 1. Add a spring washer; (simple and easy to do) 2. Use a hexagonal slotted nut + a split pin; (increase the processing process) 3 . Pad the stop washer; (increase the processing process compared with the same period of last year) 4. Insert the steel wire into the hexagon head opening of the hexagon bolt. (Increased processing steps compared to the same period of last year) Spring washers are used to prevent loosening. For example, the bolts connecting the motor and the machine base generally need to add spring washers, because the motor vibrates without the spring washers, and the nuts will loosen. Generally, the fasteners on the equipment with vibration There is a spring gasket on it, and there is generally no need to add a gasket on the flange! Whether the spring gasket is added to the flange is related to the medium circulating in the pipeline. If it is easy to generate pulses, it is best to add spring gaskets, as well as high-speed fluid, and the caliber changes frequently. Do not generalize. On some valves, the stuffing box gland All flanges need to be added with spring gaskets. The automatic selection of spring gaskets is included.
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