bolt Archives - EB Castworld

16May, 2023

Bolt Introduction And Application Analysis

Bolt

Introduction

Bolt: A mechanical part, a cylindrical threaded fastener with a nut. A type of fastener consisting of a head and a screw (a cylinder with external threads), which needs to be matched with a nut to fasten two parts with through holes. This connection form is called bolt connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolt connection is a detachable connection.

Related categories

According to the way of connection force: divided into ordinary and hinged holes.
According to the shape of the head: there are hexagonal head, round head, square head, countersunk head and so on. Among them, the hexagonal head is the most commonly used. Generally, countersunk heads are used where connections are required.
The English name of the riding bolt is U-bolt. It is a non-standard part. It is U-shaped, so it is also called a U-bolt. There are threads at both ends that can be combined with a nut. It is mainly used to fix tubular objects such as water pipes or sheet objects such as automobile plates. The spring is called a riding bolt because the way it fixes an object is like a person riding on a horse.
According to the thread length, it is divided into two types: full thread and non-full thread.
According to the tooth type of the thread, it is divided into two types: coarse tooth and fine tooth, and the coarse tooth type is not displayed in the logo of the bolt.

Bolts are divided into eight grades

Of 3.6, 4.8, 5.6, 5.8, 8.8, 9.8, 10.9, and 12.9 according to their performance grades. Among them, the bolts above grade 8.8 (including grade 8.8) are made of low-carbon alloy steel or medium carbon steel and have been heat-treated (quenched). + tempering), commonly known as high-strength bolts, and below grade 8.8 (excluding grade 8.8) are commonly referred to as ordinary bolts.
Ordinary bolts can be divided into three grades of A, B, and C according to the manufacturing accuracy. Grades A and B are refined bolts, and Grade C is rough bolts. For connecting bolts for steel structures, unless otherwise specified, they are generally ordinary rough grade C bolts.
There are differences in the processing methods of different levels, and the corresponding processing methods are usually as follows:
The bolt rods of A and B bolts are processed by lathes, with smooth surfaces and precise dimensions. The material performance grade is 8.8. The production and installation are complicated, the price is high, and they are rarely used;
Grade C bolts are made of unprocessed round steel, the size is not accurate enough, and its material performance grade is 4.6 or 4.8.
The deformation is large during the shear connection, but the installation is convenient and the production cost is low. It is mostly used for tensile connection or temporary fixation during installation.

Practical application

Bolt has a lot of call, and everyone call may be different, and someone is into screw, and someone is into bolt nail, and someone is into fastening member, and someone is into securing member. Although there are so many names, the meaning is the same, they are all bolts. A bolt is a general term for a fastener. Bolt is the physical and mathematical principle of using the oblique circular rotation and friction of the object to tighten the device parts step by step.
Bolt, be can’t do without when neutralizing in the middle of commercial production manufacture at daily life, and bolt is also referred to as the rice of industry. The utilization of visible bolt is extensively.
The operation strategies of bolt has: electronic product, engineering goods, digital product, power equipment, dynamo-electric engineering goods. Ships and ships, vehicles, hydraulic engineering, even also use bolt in chemical experiment.
Anyway it is that super many places are useful bolt.
The special precision bolt used above such as digital product. Miniature bolts used in DVD, cameras, glasses, clocks, electronics, etc.;
General bolts for television, electrical products, musical instruments, furniture, etc.;
As for engineering, construction and bridges, large bolts and nuts are used;
Vehicles, airplanes, trams, automobiles, etc. are used in combination with large and small bolts.
Vital task industrially born by bolt, as long as there is industry on the earth, then the function of bolt will be the most important.

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28Apr, 2020

Specification for High-Strength Bolts and Nuts

High-Strength Bolts and Nuts installation for Specification requirements

When we assemble a high-strength bolt connection pair, the side of the nut with a round table should face the chamfered side of the gasket. In general, when assembling a high-strength bolt connection pair with a large hexagon head, the chamfered side of the lower gasket of the bolt head should face the bolt head.
When installing high-strength bolts, the construction personnel should strictly prohibit the forced penetration of the bolts (in this case, such as hammering). If you cannot pass freely, you should use a reamer to trim the hole. The maximum diameter of the hole should be less than twice the diameter of the bolt after completion. When repairing holes, in order to prevent iron filings from falling into the seam of the board, tighten all bolts around the hole before reaming and check whether they are firm, so that the steel plate can be tilted tightly before operation. One of the places that need special attention is that gas cutting is strictly prohibited to enlarge the hole. The use of gas cutting and reaming is more likely to occur on site and requires special inspection.

There are two methods for establishing the pretension of high-strength bolts and nuts:

Torque method generally uses pointer torque (force) wrench or preset torque (constant force) wrench. At present, electric torque wrenches are more commonly used. The torque method controls the pre-tightening force by controlling the tightening torque. The tightening torque can be determined through experiments, and the pre-tightening force controlled during construction should be 1.1 times the pre-tightening force. When using electric torque to move the hand, the required construction torque tf is: where, pf is the construction preload force, which is 1 / 0.9 times of the preload force; k-the pre-construction retest torque given by the supplier Unified value of coefficient; D- diameter of high-strength bolt and nut.
In order to overcome the deformation of the plate and the washer, when installing high-strength bolts and nuts, the gap between the plate and the plate is eliminated, and the tightening torque coefficient has a good linearity, thereby improving the accuracy of the construction control preload value. First tighten with 50% tightening torque, then tighten with 100% tightening torque. After the initial tightening of the large joint, it should be tightened again according to the initial tightening torque, and then the final tightening.
Torque method is simple in strength, easy to implement and low in cost. However, due to the difference in the appearance of the connector and the joint and the tightening speed of the joint, the measured preload value is large and deformed, and the error is usually ± 25%.
Turning angle method is first tightened with a universal wrench to make the connection plate fit tightly. Then, starting from the initial tightening direction, use a long wrench or pneumatic wrench to turn the nut and tighten it to the viewpoint value. The tension of the bolt reaches the pre-tension of construction control.

Installation Method of Anchor Bolt

1. One-time embedding method: When pouring concrete, embed anchor bolts. When the tower is controlled by overturning, the anchor bolts should be buried once.
2. The reserved hole method: the equipment is in place, the holes are cleaned, the anchor bolts are placed in the holes, and the equipment is positioned and corrected, and then poured with non-shrinking fine stone concrete one level higher than the original foundation for tamping and compaction . The distance between the center of the anchor bolt and the edge of the foundation should not be less than 2d (d is the diameter of the anchor bolt), and should not be less than 15mm (d≤20 should not be less than 10mm), and not less than half the width of the anchor plate Add 50mm, when the above requirements cannot be met, appropriate measures should be taken to strengthen. The diameter of the anchor bolt used for the structure should not be less than 20mm. When subjected to earthquake action, double nuts should be used for fixing, or other effective measures to prevent loosening should be adopted, but the anchor length of anchor bolts should be increased by 5d compared to the non-seismic anchor length.
Planning the installation of anchor bolts. Handling of anchor bolts loose in the foundation. When tightening the anchor bolts, the bolts may be pulled out. At this time, the bolts should be adjusted to the original position, and the foundation around the bolts should be shoveled out of sufficient positions. Then, weld two U-shaped steel bars in the vertical and horizontal directions on the bolts, and finally clean and grouting the pit with water, wait for the concrete to solidify to the design strength, and then tighten the deviation of the live anchor bolts. The treatment method of the deviation of the live anchor bolts is roughly the same as dead. The method of anchor bolt is the same, except that the anchor bolt can be pulled out. If the bolt is too long, a section of thread can be cut off on the machine; if the bolt is too short, it can be extended by hot forging; if the position does not match, use the bending method to correct it.
Application industry is suitable for various equipment fixing, steel structure foundation embedded parts, street lamps, traffic signs, pumps, boiler installation, heavy equipment embedded fixing, etc.

The company sells: anchor bolts, stud bolts, tower bolts, embedded plates, hot-dip galvanized bolts, high-strength bolts and nuts, highway accessories, construction accessories and other products. The products are widely used in the construction engineering industry, sold well in the construction market all over the country, and exported to many places. The product quality is stable and reliable for a long time, and the service is professional and perfect.