What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Since the sub-industrial revolution, electricity has been widely used in people's lives. The application and development of electric power liberates the social productive forces and improves the social production efficiency. It is indispensable to the progress of the society. As a necessary constituent element of electric equipment, screws play an important role in the field of electric equipment. Existing screws are composed of screw heads and studs, which require specific tools to be tightened. However, during the maintenance of electrical equipment, some high-altitude workers need to carry extra screws in order to tighten the screws. the tightening tool, the staff caused great inconvenience.
At present, with the continuous improvement of microwave plasma chemical vapor deposition technology, researchers hope to obtain more excellent products by increasing the microwave power. During the use of the three screws, it is necessary to continuously adjust the length of the pins extending into the rectangular waveguide to make the reflected power of the system reach the minimum value and improve the stability of the system. Since the length of the three screws extending into the waveguide needs to be continuously adjusted with the change of the input power, and the adjustment state of the three screws cannot be recorded after the adjustment is completed, repeated adjustment is still required in the subsequent work, resulting in a time-consuming adjustment process. long and low work efficiency. Especially under high power conditions, the traditional three-screw dispenser has a high risk of microwave leakage. When manually adjusting, the human body is exposed to microwaves for a long time, which has certain potential safety hazards.
Generally, the most commonly used material on the market is iron. The iron one is known as carbon steel. It is punched out or turned. After being manufactured, it is in its natural color. In order to prevent rusting, it is necessary to Electroplated. The stainless steel rivet nuts do not need electroplating. In the case of iron, the color of electroplating is generally determined by the customer, and the color of the electroplating depends on what color the customer needs. There are also some requirements for salt spray time. Some electroplating colors have a higher salt spray time, and some electroplating, less rust in a few hours. Another point is to see whether the customer needs to export the product. Generally, the export needs to be environmentally friendly, and some domestic ones also need it, but most of them are not needed.
1. For low strength (below 500 N/mm2 or below 60000 psi) bolts use general soft steel, generally use SAE 1008 or JIS SWRM 8 (or SWRCH 8). 2. Lower strength (600 N/mm2 or 74000 psi) ) bolts use general soft steel, but limited carbon content grade, generally use SAE 1010 - 1015 or JIS SWRM 10 - 15 (or SWRCH 10 - 15). .3. Higher strength ( 800 N/mm2 or 125000 psi ) bolts of medium carbon steel, low carbon boron steel plus quenching and tempering, generally use SAE 1035 - 1040 or SWRCH 35K - 40K. 4. High strength (900 N/mm2 or more or 150000 psi or more) bolts use medium carbon Alloy steel or low carbon boron steel, in terms of application, if the metric Class 10.9 uses low carbon boron steel, the imprint should be added under the series imprint to become 10.9, and the imprint of the inch 8.2 grade is also used with the general Grade 8 bolts The imprint is different for easy identification. High-strength bolts made of low carbon boron steel cannot be used in high temperature conditions. The design strength exceeds Class 12.9 or ASTM A574 ultra-high strength bolts are limited to medium carbon alloy steel plus quenching and tempering. The performance grades of bolts for steel structure connection are divided into more than 10 grades such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, etc. Among them, the bolts of grade 8.8 and above are made of low-carbon alloy steel or medium-carbon steel and are heat-treated (quenching, tempering), commonly known as high-strength bolts, the rest are commonly known as ordinary bolts. The bolt performance grade label consists of two parts of numbers, which represent the nominal tensile strength value and yield ratio of the bolt material respectively. For example, a bolt with a performance level of 4.6 means: 1. The nominal tensile strength of the bolt material is 400MPa; 2. The yield ratio of the bolt material is 0.6; 3. The nominal yield strength of the bolt material is 400×0.6=240Mpa . Performance level 10.9 high-strength bolts, after heat treatment, can achieve: 1. The nominal tensile strength of the bolt material is 1000MPa; 2. The yield ratio of the bolt material is 0.9; High-strength bolts, processing and manufacturing problems are compared Small, general fastener manufacturing companies can master the manufacturing process; but problems are prone to occur in material selection and heat treatment. Material selection is the primary link. Various alloying elements have a great influence on the properties of the material, and the material must be subjected to spectral composition analysis; secondly, the fracture problem and the choice of heat treatment process have a great influence and are very important. Dealers and traders must control the inspection and performance testing links; automotive fasteners have high requirements and must carefully control the quality.
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