What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
As we all know, when installing the outdoor unit of the air conditioner, most of the installers need to hang it on the outer wall. When tightening the machine foot screws, they all need to lean out of the window or climb out the whole person, and use a wrench to tighten it. . Therefore, it is difficult for the installer to operate, and it is easy to drop the installation materials such as screws and nuts, which is not only a waste of materials, but also easy to hurt personnel. The purpose of Guangdong Yueluo Hardware Industry Co., Ltd. is to solve the above problems, and provide a safe and labor-saving air conditioner outdoor unit machine foot screw installer that the installer does not have to lean out of the window or climb out of the room, and the installation materials are not easy to fall.
Several concepts about high-strength bolts 1. According to the specified performance level of bolts above 8.8, they are called high-strength bolts. The current national standard only lists M39. For large-size specifications, especially those with a length greater than 10 to 15 times High-strength bolts, domestic production is still short-term. The difference between high-strength bolts and ordinary bolts: High-strength bolts can withstand larger loads than ordinary bolts of the same specification. High-strength outer hexagon bolts High-strength outer hexagon bolts are made of Q235 (ie A3). The material of high-strength bolts is 35# steel or other high-quality materials, which are heat-treated after being made to improve the strength. The difference between the two is the difference in material strength. From raw materials: High-strength bolts are made of high-strength materials. The screws, nuts and washers of high-strength bolts are all made of high-strength steel, such as No. 45 steel, 40 boron steel, 20 manganese titanium boron steel, 35CrMoA, etc. Ordinary bolts are usually made of Q235 (equivalent to A3 in the past) steel. In terms of strength grades: high-strength bolts are increasingly used. Two strength grades are commonly used, 8.8s and 10.9s, of which 10.9 is the majority. The strength level of ordinary bolts is lower, generally 4.4, 4.8, 5.6 and 8.8. High-strength bolts High-strength bolts are viewed from the force characteristics: high-strength bolts apply pretension and transmit external forces by friction. Ordinary bolt connection relies on the shear resistance of the bolt and the bearing of the hole wall to transmit the shear force. When the nut is tightened, the pre-pressure is very small, and its influence can be ignored. In addition to its high material strength, high-strength bolts also exert a large amount of pressure on the bolts. The pre-pressure generates extrusion force between the connecting components, so that there is a large friction force perpendicular to the direction of the screw, and the pre-pressure, anti-slip coefficient and steel type directly affect the bearing capacity of high-strength bolts. According to the force characteristics, it is divided into pressure type and friction type. The calculation methods of the two are different. The minimum specification of high-strength bolts is M12, and M16~M30 are commonly used. The performance of super-large bolts is unstable and should be used with caution in design.
Knurled copper nut, the specification is M5X8X12, the outer circle is 8.0MM, and the height is 12MM. Material: C3604 (ROHS PASS) brass. The thread still guarantees 6H accuracy. This knurled copper nut is used in power tools. Unlike other knurled copper nuts, the diamond pattern of this knurled copper nut is located in the middle of the product, and the diamond-shaped mesh knurled wheel edge The large outer circular step surface is rolled out of diamond-shaped flowers.
The following standards contain provisions which, through reference in this standard, constitute provisions of this standard, and at the time of publication of this standard, the editions indicated were valid. All standards are subject to revision and parties using this standard should explore the possibility of using the latest edition of the following standards. GB/T90-1985 Fasteners Acceptance Inspection, Marking and Packaging -1985 Cross recessed screws GB/T1237-2000 Fastener marking method GB/T3098.1-2000 Mechanical properties of fasteners Bolts, screws and studs GB/T3098.6-2000 Mechanical properties of fasteners, stainless steel bolts, Screws and studs GB/T3098.10-1993 Mechanical properties of fasteners Bolts, screws, studs and nuts made of non-ferrous metals GB/T3103.1-1982 Fastener tolerances Bolts, screws and nuts GB/T3106-1982 Bolts , The nominal length of screws and studs and the thread length of ordinary bolts -2000 Fastener surface defect bolts, screws and studs, general requirements GB/T16938-1997 Fastener bolts, screws. Studs and nuts general technical conditions
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