Fastener is a common connecting part in our life. It has a wide range of applications, ranging from screws on watches to large mechanical parts or aircraft bolt and nut connections. However, despite its simple structure, there are many things to pay attention to in the process of use. Next, Xiao Rui will take you through an inventory of the most common wrong operations in the use of fasteners, hoping to help you.
Replace fine teeth with coarse teeth
There are many important connections on the machine, such as transmission shaft, etc. most of the bolts are fine thread. In case of missing parts during maintenance, some maintenance personnel will be lazy to use coarse tooth bolts instead, which should not be.
Because the inside diameter of fine tooth bolt is large, the pitch and external angle are small, the strength is high, the self-locking performance is good, and the ability to withstand impact, vibration and exchange load is also strong. Once the coarse tooth bolt is used as a substitute, it is easy to loosen, fall off, disassemble and even cause serious mechanical accidents, so this should be noted.
2. pore mismatch
The bolts on the machine that bear transverse load and shear force, such as transmission shaft bolts and flywheel bolts, are fitted with bolt holes in a transitional way. The assembly should be firm and reliable and can bear lateral force. Some workers do not pay attention to inspection during assembly, and continue to install when there is a large gap between the bolt and the bolt hole, which is prone to bolt loosening or cutting accidents.
3. thicken the nut to increase the connection reliability
Some people mistakenly believe that thickening the nut can increase the number of working turns of the thread and improve the reliability of the coupling. But in fact, the thicker the nut is, the more uneven the load distribution among the threads is, and the coupling is easier to loosen.
4. one female with multiple pads
After installation, sometimes the bolts are too long. Some workers will install additional spring washers on the bolts. In this case, the spring washers will be broken due to uneven stress during the consolidation process, which will reduce the pre tightening force of the bolts, and may also produce eccentric loads, reducing the reliability of the bolt connection.
5. tighten it tightly
Many staff members have such misconceptions: they think that the bolts should be "rather tight than loose", so they deliberately increase the tightening torque, resulting in bolt slippage. In addition, some important bolts that need to be tightened with torque, but some people use adjustable wrenches to tighten them because they are trying to save time. As a result, the torque is insufficient, resulting in bolt looseness and even mechanical failure.
6. the washer is too large
In case of lack of washers of appropriate size, some workers will replace them with washers with larger inner diameter. In this case, the contact area between the bolt head and the washer is small, which will reduce the bearing pressure or locking force of the washer. If there is vibration and impact in the working environment, the bolt is easy to loosen.
7. improper locking
Important bolts shall be locked with locking devices after assembly, which are described in four cases. If the split pin is used for locking, it is not allowed to lock with too thin open lock or half open lock; If the spring washer is used for locking, it is not allowed to use the one with too small staggered distance of washer opening; If the locking plate is used for locking, the locking plate shall not be locked at the edges and corners of the nut; If double nuts are used for locking, thinner nuts shall not be installed outside.
8. false firmness
If the bolts, nuts or threads are rusted, or there are impurities such as scale and iron filings, they must be cleaned before assembly; Burrs, sediment and other impurities on the joint surface of the connector shall also be removed. Otherwise, when the bolt is tightened, it seems that it is tightened on the surface, but in fact, the connector is not really compacted due to the obstruction of these foreign matters. Under such false firmness, the bolt will quickly loosen in case of vibration, load impact and temperature change.
Display of some products of Jinrui
Jiangsu Jinrui metal products Co., Ltd. is the production base of Shanghai Jinrui standard parts. The factory covers an area of more than 20000 square meters, with a registered capital of 50million yuan, a total investment of more than 100million yuan, and an annual output of more than 20000 tons. Its products are exported to more than 40 countries overseas.
Since its establishment in 2001, Jinrui company has developed into a new layout with Jiangsu Haian as its production base and Shanghai Baoshan and Henan Nanyang as its sales centers after more than 20 years of unremitting efforts.
At present, Jinrui's main products include the following six categories:
1. the main bolt products include: metric and American round head oval neck bolts (also known as fishtail bolts), inner and outer hexagon bolts, hexagon flange bolts, carriage bolts, hub bolts, etc
2. stud products: full thread thread thread, double head studs, etc
3. nut products: Hexagon nuts, flange nuts, heavy nuts, square nuts, butterfly nuts, etc
4. screw products: self tapping screws, self tapping and self drilling screws, wood screws, various machine screws, etc
5. washer products: flat washer, spring washer, square washer, locking washer, etc
6. fastener related non-standard products
Jinrui's wire drawing plant also provides processing services such as fine drawing, coarse drawing and spheroidization of wire rods, and supplies finished wire rods of various domestic big brand steel mills.
Based on the business philosophy of "pioneering innovation and pursuing excellence", Jinrui has successively introduced multiple models of heading and forming machines, threading machines, nut machines, hot heading and rolling machines, lathes, large hot heading machines and their supporting testing equipment, such as magnetic particle flaw detectors, metallographic analyzers, salt spray testing machines, direct reading spectrometers and optical screening machines, tensile machines, Vickers hardness testers, Rockwell hardness testers, etc., and has established an independent R & D department, It can produce various high-quality fasteners such as GB, DIN, ANSI, JIS and ISO international standards. The products are widely used in the fields of petroleum, chemical industry, boiler, wind power generation, highway guardrail, elevator guide rail, machinery manufacturing, construction sites, auto parts and medical devices.
Since its establishment, Jinrui has developed vigorously. It integrates the advantages of each company, carefully designs and strictly selects materials to make the products more durable and highly praised by the majority of users. Jinrui won the ISO9001:2000 international quality system certification in 2001, the special equipment manufacturing license in 2010, and the TS16949 automobile quality management system certification in 2012. The people's Insurance Company of China underwrites the "global product liability insurance" to ensure that every screw should be used with confidence, firmness and peace of mind!
No matter now or in the future, Jinrui will always grasp the core service concept of "quality first, invigorating the enterprise through science and technology, putting users first and providing considerate service", and sincerely provide you with high-quality services and high-quality products. Jinrui will also become your most loyal and long-term partner.
