What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
At present, shaft retaining rings are mainly divided into three categories: elastic retaining rings for shafts, flattened wire retaining rings for shafts, and wire retaining rings for shafts. Among them, the spring retaining ring for the shaft is generally installed with circlip pliers, and the flattening wire retaining ring for the shaft and the wire retaining ring for the shaft are generally installed with a sharp screwdriver or needle-nose pliers. The defects and deficiencies of these two methods will be discussed in detail below: First, the above two installation methods require the operator to use a large force to open the retaining ring, which is more laborious; For the installation of the flattened steel wire retaining ring for the shaft and the steel wire retaining ring for the shaft, because the wire retaining ring has low elasticity and has no force point, it is very easy to cause the retaining ring to break or the installation tool to slip during the installation process. Higher skills and experience can be competent for the installation of wire retaining rings.
Procurement and sales in the testing process know that the quality of screws is manufactured, not detected, but in manufacturing, we must try our best to make them as good as possible. But it is unlikely to be completely error-free and error-free. We all know that errors are unavoidable and can only be approached infinitely. Therefore, at this time, the quality inspection of the screw is required to improve the quality of the screw. At the beginning of ordering from screw wire material into the production of screw industry manufacturers, you must first check the wire diameter of the screw wire and the material of the screw. Generally, the wire diameter of the screw is measured with a caliper to measure the size of the wire diameter, whether it is suitable for self-ordering. Same size. After testing these, it is the testing in the production process, starting from the head of the screw, to determine the size of the head, the opposite side of the head, the diagonal angle, the depth of the cross groove, the tolerance range of the screw, and so on. These are checked with calipers. In the inspection of all aspects when rolling teeth, the main thing is whether the thread can pass the pass and stop gauge, and whether the screw thread can pass the gauge and stop. Next is the electroplating measurement problem. After electroplating, whether it meets the requirements of environmental protection and whether it can pass the time required by the salt spray. Tools include environmental testing machines and salt spray testing machines. In short, in the process of screw production and sales, there must be necessary tools to detect the quality of screws. The summary should be summarized as follows: calipers, hardness testers, salt spray machines, environmental testing machines, pass and stop gauges, etc. When producing and selling screws, there will be a screw specification and screw model. With the screw specification and screw model, we can understand what specification screw and what size screw the customer needs. Many screw specifications and screw models are based on national standard specifications and models. Generally, such screws are called ordinary screws, which are generally available on the market. There are some non-standard screws, which are not based on the national standard specifications, models and sizes, but are customized according to the standards required by the product materials. There is no stock in the general market at all. In this way, it is necessary to make drawings and samples.
Countersunk head screw, also called countersunk head screw, also known as flat machine screw, is a kind of construction part. The head is a 90-degree cone, similar to common wood screws. The head has tool tightening grooves, such as a zigzag, cross, inner hexagon, plum blossom, pentagon, etc. Screws are all connectors used to connect two objects. Generally, the head of the screw will protrude above the surface of the object to be connected, so that the surface will lose its smoothness. Countersunk head screws can be sunk under the surface to make the surface flat. For hard objects, countersunk holes need to be drilled in the corresponding positions of the countersunk head. In short, the countersunk head is the head of the screw that can keep the surface flat after installation.
At present, many manufacturers do not want the product to be disassembled by the user, so they set the anti-disassembly mark on the product. The common method is to apply red or blue anti-disassembly paint on the fastener, such as the nut, once the user disassembles it by himself. , the paint at the connection will fall off, and it can no longer be aligned, so that the manufacturer can judge and identify it and provide a basis for warranty. However, it is inconvenient to paint some joints, and the use of tamper-evident paint is not healthy and environmentally friendly.
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