What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
rivet is a metal rod-shaped part with a cap at one end. During riveting, the rivet uses its own deformation or interference to connect the riveted parts. Commonly used rivets are semi-circular head, flat head, semi-hollow rivets, solid rivets, countersunk head rivets, blind rivets, hollow rivets, etc. At present, rivets are widely used in various backplane products and other stamping products. Since rivets are responsible for the functions of locking, positioning and bearing lateral force in the product, the degree of riveting and vertical have higher requirements. However, in actual production, there are often problems such as the failure of the rivet torsion to meet the requirements, the rivet being skewed by the rivet, the surface of the rivet being cut, the rivet placement being inaccurate and requiring manual repositioning, etc. Very high and very inefficient.
The main categories of screws include ordinary screws, machine screws, self-tapping screws and expansion screws. Cap screws used to be limited to full-thread fasteners. Hex cap screw and Hex bolt Hex bolt As the name suggests, it is a male threaded fastener with a hexagonal head, designed to be turned with a wrench. According to the ASME B18.2.1 standard, the head height and shank length tolerance of the hexagon head screw (Hex cap screw) is smaller than that of the general hex bolt (Hex bolt), so the ASME B18.2.1 hexagon screw is suitable for installation in all hexagon bolts that can be used. places, also including places where the large hex bolts are too large to be used. Socket cap screw (also known as socket head screw or) is a screw with a hexagonal inner hole on the head, which can be tightened or loosened only after a hexagonal ruler (hex key, Allen wrench or Allen key) is inserted into the inner hole. The most commonly used hexagon socket head screws are cylindrical head screws with a head diameter of about 1.5 times the main diameter of the thread (1960 series). Countersunk head cap screw. The counterbore design allows the screw head to rotate without being exposed on the surface of the fixed object, so it is mostly used in places where the surface is small and traditional wrenches are inconvenient to use. Machine screw is generally a screw (4#~12#) with a diameter less than ¼ inches, usually full teeth and rotated by a screwdriver, such as slotted, cross or hexagon socket. Wood screws, machine screws; but can be divided into many categories according to different uses; machine screws can be divided into longitudinal tightening screws and horizontal expansion screws; according to the thread can also be divided into: A: Triangular thread (60 degrees ) : combined/locked/expanded B: triangular thread for pipe (55 degrees): combined/locked 3) C: trapezoidal thread (30 or 29 degrees): power transmission D: square thread (90 degrees): power transmission stainless steel screw Stainless Steel Anti-Drop ScrewsStainless Steel Anti-Drop Screws Machine (Treadmill) Screws And Shafts For Motorcycle Or Bicycle Needle Car Screws, Axes Screws And Shafts For Sewing Macing Socket Set Screws Stainless Steel Wide Thread ScrewsStainless Steel Coarse Thread Screws Stainless Steel High-Low Thread Screws Stainless Steel Machine Screws Stainless Steel Self Drilling Screws Stainless Steel Self Tapping Screws Stainless Steel Self Tapping Screws Stainless Steel Thread Cutting Screws Stainless Steel Triangle Stainless Steel Tri-Lobular Thread Screws Model Description P refers to the head type is PAN head; A refers to the pointed tail teeth, B refers to the flat tail teeth, namely PA round head pointed steel teeth, PB round head flat mouth steel teeth. Self-tapping type: ◆Round head self-tapping screw PA ◆Round head flat tail self-tapping screw PB ◆Round head cutting tail self-tapping screw PT ◆Round head belt self-tapping screw PWA ◆Round head belt and flat tail self-tapping PWB ◆Round head belt Jiecut tail self-tapping PWT ◆Countersunk head self-tapping screw KA ◆Countersunk head flat tail self-tapping screw KB ◆Countersunk head cut-tail self-tapping screw KT ◆Semi-countersunk head self-tapping screw OA ◆Big head self-tapping screw BA ◆Big head flat tail self-tapping screw BB ◆Large flat head self-tapping screw TA ◆Large flat head flat tail self-tapping screw TB ◆Large flat head cutting tail self-tapping screw TT ◆Thin head self-tapping screw CA ◆Thin head flat tail self-tapping screw CB ◆Cup head hexagon socket self-tapping HA ◆Drywall/Wallboard/Fiber Nails Machine Wires: ◆Round Head Machine Screw PM ◆Round Head Machine Screw PWM ◆Large Flat Head Machine Screw TM ◆Countersunk Head Machine Screw KM ◆Half Countersunk Head machine screw OM ◆Large head machine screw BM ◆Thin head machine screw CM ◆Cup head machine screw HM
1. Correctly select the product a. Before use, confirm whether the mechanical properties of the product can meet the needs of use, such as the tensile strength of the screw and the guaranteed load of the nut. The length of the screw should be selected appropriately, and the 1-2 pitch of the nut will be exposed after tightening. b. Before use, check whether the threads are rough, and whether there is iron filings or dirt between the threads, which often lead to locking. c. The fasteners can be lubricated before use. It is recommended to use butter, molybdenum disulfide, mica, graphite or talc for lubrication. Generally, dipping wax is used for lubrication and anti-locking. [1] 2. Pay attention to the use method when using it. a. The speed and force of screwing in should be appropriate, not too fast or too large. Use a torque wrench or socket wrench as much as possible, and avoid using an adjustable wrench or an electric wrench. Excessive speed will cause the temperature to rise rapidly and cause lock-up. b. In the direction of force, the nut must be screwed in perpendicular to the axis of the screw. c. The use of washers can effectively prevent the problem of over-tightening.
The working principle of the nut is to use the friction between the nut and the bolt for self-locking. However, the reliability of this self-locking is reduced under dynamic loads. In some important occasions, we will take some anti-loosening measures to ensure the reliability of the nut locking. Among them, the use of lock nuts is one of the anti-loosening measures. There are also two types of locking nuts. One is to use two identical nuts to screw on the same bolt, and a tightening torque is added between the two nuts to make the bolt connection reliable. The other is a special lock nut, which needs to be used together with a lock washer. As shown in FIG. 1, a plastic gasket 2 is arranged in the center of the nut 1 to play a locking effect, but the process is complicated and the production is inconvenient. One is to drill through threaded holes from the outer surface of the nut to the inner thread surface (usually 2, distributed at 90 on the outer surface), which are used to screw in small-diameter countersunk head screws. The purpose is to apply a thread to the thread. A centripetal force prevents the lock nut from loosening. At present, the lock nut with better quality on the market is inlaid with small copper pieces that are consistent with the thread of the lock nut on the inner surface of the nut, which is used to prevent the radial jacking screw from directly contacting the locked thread and being damaged. By. This kind of lock nut is gradually applied in the shaft end locking of rotating motion parts, such as the anti-looseness of the bearing at the mounting end of the ball screw. The process is equally complex.
The above content is uploaded by Yueluo or the Internet. If there is any copyright issue, please contact [email protected].
