What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The production of stud bolts requires fixed equipment and machine tool processing. Of course, the processing procedure is relatively simple. There are mainly the following procedures: first, the material needs to be pulled out. After this process, the next process can be carried out. The next process is to use a cutting machine to cut the straight and long material into the length required by the customer according to the customer's requirements. This completes the second process. The third process is Put the cut short material on the thread rolling machine and roll out the thread; the ordinary stud bolts are processed here, of course, if other requirements are required, other processes are required. [1] The commonly known bolt refers to the screw with a larger diameter. According to this statement, the diameter of the screw is much smaller than that of the bolt. Stud bolts do not have a head, and some are called studs. Both ends of the stud are threaded, with no thread in the middle and a smooth rod in the middle. Studs are used on large equipment such as gear racks. In actual use, the external load will have vibration and the influence of temperature will reduce the frictional force, and the threaded connection will loosen and fail over time. Therefore, it is necessary to do a good job in the maintenance of the stud bolts at ordinary times. Stud bolts or anchor bolts will have problems under the action of mechanical friction for a long time. When problems occur, the engine oil pan should be removed, and the use of the engine bearing bushes should be carefully checked, and the clearance between the bearing bushes should be checked. Whether it is too large, if the gap is too large, it should be replaced in time. When replacing the stud bolts, also replace the connecting rod bolts. When some large equipment such as nail making machines are in normal operation, if they find that the engine is not running very stable or there is abnormal noise, they should stop and check in time to avoid bigger problems. [1] In each maintenance, the newly replaced stud bolts and other accessories should be inspected. During the inspection, the focus should be on the head and guide part of the stud bolt. Whether there are cracks or dents in each part, and also check whether the tooth shape of the stud bolt has changed. Is there any abnormality in the thread pitch? If there is any abnormality, it must not be used again. A torque wrench should be used when installing the connecting rod cover. It must be tightened according to the specified standards, the torque should not be too large or too small, and attention should be paid to selecting the stud bolts and studs of the supporting manufacturer.
At present, during assembly of many pin installation mechanisms, the pins need to be installed into the holes or arranged in an orderly manner, and there are many problems in this assembly method. First of all, during assembly, if the hole diameter of the hole product is large, when the pin enters the hole of the hole product, part of the pin entering the hole of the hole product is not fixed, which often leads to slight deviation. In addition, this assembly method is usually only suitable for parts with large apertures and small depths, and when installing multiple pins, it is impossible to automatically install all pins in place due to space constraints. Special tools need to be made for installation operations, and it is easy to cause pins. damage.
In many national standards, there will be a division of intensity levels. Combination screws are no exception. The strength grade of the combined screw is divided according to the material of the screw wire and the hardness index of the screw wire. General combination screw materials are divided into stainless steel and iron, stainless steel is divided into stainless steel 201, stainless steel 304 and stainless steel 316 and so on. Iron is divided into three types: low carbon steel, medium carbon steel, and high carbon steel. Carbon steel combination screws refer to iron combination screws. Generally, iron combination screws are classified into grades 4.8, 8.8, 10.9, and 12.9. However, the combination screws of grade 10.9 and grade 12.9 are rarely used in the market, so we will not talk about them here. And the combination screws on the market are more commonly used combination screws of grade 4.8 and 8.8. 4.8 grade combination screws are generally made of 1010A screw wire rods. After the screw wire rods are beaten into screws, they are combined with spring flat washers. After production, this 4.8 grade combination screw does not need to be hardened. Its hardness can reach 4.8. 8.8 grade combination screws are generally made of screw wire 10B21 piers. After the screw and wire piers are made into screws, they are equipped with spring washers and flat washers. They can pass through the automatic elastic flat washer machine to rub the three pieces together. Fasten the spring-flat washer combination on the screw, and the spring-flat washer will not fall off. After the combination screw is produced, it needs to be hardened to make the hardness reach 8.8. After the hardness reaches 8.8, we need to take it for electroplating. In order to prevent hydrogen embrittlement of the spring washer in the 8.8-level combination screw with added hardness, it is easy to break. In this way, we have to perform hydrogen removal treatment on the hardened combined screws, and only after the hydrogen removal can be plated. In short, there are many kinds of standard grades of combined screw strength, but generally only two types are used in the market, one is the 4.8-level combined screw strength, and the other is the 8.8-level combined screw strength. 4.8-level combination screws are the most used in the market and customer needs, and have a wide range of applications. As for the standard strength of 8.8-level combination screws, we generally refer to 8.8-level hexagon socket head combination screws, 8.8-level pan head combination screws, and 8.8-level external hexagon combination screws. These three are more commonly used.
The screw is a fairly common structure in the technical field of machine parts assembly, and it mainly uses the mutual engagement characteristics of male and female threads to achieve the purpose of pressing the workpiece. At present, there are many kinds of screws on the market, and their functions are also very different. However, a stud and a rotating part by which the stud is rotated are the same basic structure.
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