Types of commonly used threaded
fasteners
A) Bolt
The bolt consists of two parts: a bolt head and a bolt rod. Hexagonal head shapes are the most widely used. The commonly used grades are A and B. At the same time, there are full threads, partial threads, and thick and thin rods. The size of the bolt specification is determined by the nominal diameter d of the bolt and the length l of the bolt. After a bolt is selected, the dimensions of other parts can be checked according to the relevant national standards.
B) Double-ended stud
Double-ended studs are threaded at both ends, one end is screwed into the prefabricated screw hole of the connected part, called the screw-in end; the other end is screwed with the nut to fasten the other connected part, called the fastening end. In terms of structure, it is divided into two types: A-level and B-level. Grade A should be marked with "A" in front of the specification, while grade B can be omitted. The screw-in end length bm of the double-ended stud is related to the material of the connected parts with screw holes:
(1) Bronze and steel, take bm=d
(2) Cast iron, take bm=1.25d
(3) Aluminum alloy, take bm=1.5d
(4) For non-metallic materials, take bm=2d
The size that determines the specifications of the double-headed stud is the stud diameter d and the length of the fastening end l. After a type of double-headed stud is selected, the dimensions of other parts can be found according to the relevant standards.
C) Screw
According to the nature of use, screws can be divided into two types: connecting screws and set screws. The former is used for connection, depending on the shape of the head, there are slotted cylinder head screws, slotted countersunk head screws, slotted pan head screws, etc. The latter is mainly used to prevent relative movement between two matching parts. There are slotted flat end set screws, slotted cone end set screws, hexagon socket flat end set screws, etc. The size that determines the screw specification is the screw diameter d and the length l. The dimensions of other parts can be found according to relevant standards.
D) Nut
Nuts are used in conjunction with bolts or studs to connect. There are hexagonal, round, square, etc.
nuts in the form of nuts, and the most common application is hexagonal head nuts. Round nuts are often used for axial fixation of parts on shafts. Hexagon head nuts are divided into types I, II, A, B, and C, as well as thickness and thickness. The size that determines the
nut specification is the nominal thread diameter D. After a nut is selected, the dimensions of other parts can be found according to the relevant standards.
E) Washer
The washer is installed between the nut and the connected piece, and its purpose is to increase the contact area between the nut and the connected piece and protect the surface of the connected piece from being scratched when the nut is tightened. In addition to flat washers, there are spring washers and stop washers, etc., which can prevent the nut from loosening due to vibration.
