What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Sometimes, the iron screws are often seen broken, and sometimes, the stainless steel screws are also seen broken. But generally speaking, stainless steel screws rarely break. Because the stainless steel screw wire itself is relatively hard. But under certain circumstances, stainless steel screws can still break. So what are the main reasons for stainless steel screws to break? The reasons for the fracture of stainless steel screws are as follows: 1. The quality of raw materials used for stainless steel screws is poor, and the quality of stainless steel screws is not good. There are many impurities, impure, resulting in insufficient hardness of stainless steel screws. 2. The production process of stainless steel screws. For example, stainless steel screws with eccentric head and eccentricity, and the Q value is too deep and the R position design is too small during the down punching operation during production. 3. The customer uses too much force when using stainless steel screws. Generally, you do a torque test to see how much the minimum breaking force is, and then adjust the torque. Of course, stainless steel screws must be broken for more than three reasons. But the above three reasons are the main reasons for the fracture of stainless steel screws. When the stainless steel screw is found to be broken, it can be checked step by step. Find out what's causing it.
Lock washers feature easy installation. 1. Just place the helical tooth surfaces on the inner side of the two washers against each other and place them between the nut and the connecting material; 2. After the nut is tightened, the radially convex surface on the outer side of the lock washer and the contact surfaces at both ends are in an engaged state, and The angle of the slope angle of the helical tooth surface on the inner side of the washer is greater than the thread angle of the bolt; 3. When the bolt is elongated due to mechanical vibration, the nut will rotate and loosen accordingly. Because the frictional force of the outer radial convex surface of the lock washer is greater than the frictional force between the inner helical tooth surfaces. In this state, only the relative dislocation between the inner helical tooth surfaces is allowed to generate a certain lifting tension; 4. When the bolt shrinks, the helical tooth surface of the washer will make the nut return to its original position. So as to achieve 100% anti-loose and tightening effect; 5. Washers are suitable for relatively flat and smooth surfaces; 6. If the connecting material is non-metallic material, a metal plate can be fixed on the connecting material, so that the Use the lock washer; 7. There is no need to use a torque wrench when installing the lock washer; 8. You can choose to use an air tool when installing or removing the lock washer.
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.
In another embodiment of Guangdong Yueluo Hardware Industrial Co., Ltd., the conveying device 3 includes a motor 31 and a circular rotating disk 34, the motor 31 drives the circular rotating disk 34 to rotate, and the circular rotating disk 34 is evenly provided with screws in the circumferential direction. The matching screw accommodating hole 35, the screw enters the screw accommodating hole 35, the motor 31 drives the circular rotating plate 34 to rotate, so that the screw is first slotted by the cutting wheel 42, and then polished by the fixing wheel 48, and the screw is in the screw accommodating hole 35. It is fixed, which is more secure and reliable during the slotting process. Preferably, the circular rotating disk 34 includes a circular rotating disk 32 and a sector-shaped fixed disk 33. The circular rotating disk 32 is evenly provided with screw receiving recesses matching the screws in the circumferential direction, and the recesses and the sector-shaped fixed disk 33 are formed with the screws The matching screw receiving holes face the cutting wheel 42 and the fixing wheel 51 .
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