What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Round head three-combination screws are also called pan-head three-combination screws, which are divided into large pan-head three-combination screws and small pan-head three-combination screws. The materials are divided into stainless steel and iron. The stainless steel round head three-combination screws include stainless steel small pan head three-combination screws and stainless steel large pan-head three-combination screws. The national standards are respectively expressed as GB9074.8 and GB9074.4.
The bolt thread is generally cold worked, so that the thread blank within a certain diameter range passes through the rubbing (rolling) wire plate (die), and the thread is formed by the pressure of the wire plate (rolling die). The plastic streamline of the threaded part is not cut off, the strength is increased, the precision is high, and the quality is uniform, so it is widely used. In order to make the outer diameter of the thread of the final product, the required thread blank diameter is different, because it is limited by factors such as thread accuracy and whether the material is coated or not. Rolling (rubbing) thread is a processing method that uses plastic deformation to form thread teeth. It uses a rolling (screwing plate) die with the same pitch and tooth shape as the thread to be processed, while extruding the cylindrical screw blank, while rotating the screw blank, and finally transferring the tooth shape on the rolling die to the On the screw blank, the thread is formed. The common point of rolling (rubbing) thread processing is that the number of rolling revolutions does not need to be too much. If it is too much, the efficiency will be low, and the surface of the thread teeth will easily cause separation or random buckle. On the contrary, if the number of revolutions is too small, the diameter of the thread is easy to be out of round, and the pressure at the initial stage of rolling increases abnormally, resulting in a shortening of the life of the die. Common defects of rolled threads: cracks or scratches on the surface of the thread part; random buckles; out of roundness of the thread part. If these defects occur in large numbers, they will be discovered during the processing stage. If the number of occurrences is small, the production process does not notice these defects and then circulates to users, causing trouble. Therefore, the key issues of processing conditions should be summarized, and these key factors should be controlled in the production process.
The inch thread is the thread size marked in inch. According to the shape, it is divided into two types: cylindrical and conical; according to the tooth angle, it is divided into two types: 55° and 60°. The 1/4, 1/2, 1/8 marks in the thread refer to the diameter of the thread size in inches. One inch equals 8 cents, 1/4 inch equals 2 cents, and so on.
The existing spring screw includes a screw rod, a spring connecting sleeve, a spring, a fixed connecting sleeve, a nut and a nut sleeve, wherein the screw rod includes a screw cap, a connecting section without threads and a threaded connecting section with threads, and the connecting section is located in the screw cap and the thread. A shaft shoulder is arranged between the connecting sections and between the connecting section and the threaded connecting section, the connecting section of the screw is sleeved with a spring connecting sleeve, a spring and a fixed connecting sleeve, the spring connecting sleeve is close to the screw cap, and the connecting sleeve is connected between the spring connecting sleeve and the fixed connecting sleeve The connection spring is connected with a threaded nut on the threaded connection section of the screw, and the nut sleeve is connected to the nut sleeve. The fixed connection sleeve is fixedly connected to the upper die of the steel mold through bolts, and the nut sleeve is welded to the lower mold of the steel mold. When clamping the mold, a professional is required to turn the screw from the lower mold to the upper mold or hook it to the upper mold with a foot and then tighten it with the wind, which is inconvenient to install, has low work efficiency, and has potential safety hazards. Contents of the utility model Yueluo Guangdong Yueluo Hardware Industry Co., Ltd. aims to provide a spring screw that is easy to operate. In order to solve the problems existing in the background technology, Guangdong Yueluo Hardware Industry Co., Ltd. adopts the following technical scheme: a spring screw, including a screw rod, an upper compression spring washer, a spring, a fixed sleeve, a lower compression spring washer, Base and fixing nut. The screw rod includes a screw cap, a connecting section without threads and a threaded connecting section with threads, the connecting section is located between the screw cap and the threaded connecting section, and a shaft shoulder is arranged between the connecting section and the threaded connecting section. The connecting section of the screw rod is sleeved with an upper compression spring washer, a spring, a fixing sleeve, a lower compression spring washer and a base, and the threaded connection section is connected with a fixing nut. A fixed sleeve is sleeved between the connection section and the threaded connection section, and the fixed sleeve is sleeved with a lower pressure spring washer and a base. The upper compression spring washer is close to the screw cap, the lower compression spring washer is fixed on the base by four screws, the spring is placed between the upper compression spring washer and the lower compression spring washer, and one end of the spring is sleeved with the upper compression spring washer , and the other end is sleeved with a fixed sleeve. For Yueluo, the diameter of the spring screw is between T20-T27. In this preferred solution, the use performance of the spring is high, which is beneficial to prolong the service life of the spring screw. For Yueluo, preferably, the thread connecting section of the screw adopts T-shaped thread. In this preferred solution, the fixing nut is tightly matched with the threaded connection section, so that the steel mold is clamped tightly. Yueluo is preferably made of 40Cr material for the fixing nut and screw. In this preferred solution, the rigidity of the fixing nut and the screw rod is high, which is beneficial to improve the usability of the spring screw. Yueluo is preferred, the spring screw parts except the fixing nut and the screw rod are made of 47# steel material. In this preferred solution, the production cost is low. In summary, Guangdong Yueluo Hardware Industry Co., Ltd. brings the beneficial effects: when the spring screw is used, it is only necessary to use a wrench to move the fixed nut, which is convenient for installation, disassembly and replacement, improving work efficiency and reducing production costs.
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