【Summary】The first is the punching of the head, where the head of the screw is punched out of the wire and the wire is cut. The second is thread rolling, where two files are used to thwart the threads on top of the previous process.
The first is the punching of the head, where the head of the screw is punched out of the wire and the wire is cut. The second is thread rolling, where two files are used to thwart the threads on top of the previous process.
The equipment used is the same as the name of the process: the punching machine and the thread rolling machine.
As for the technical aspects, the main thing is to choose a die for the punching part that meets the criteria for use, such as T10, etc., and to consider the length of the threaded part when cutting it off. The thread threads are adjusted by the distance between the two files. This basically covers the geometric requirements of the screw.
Most screws are finished with a surface treatment, heat treatment, etc. Finally, the outer diameter of the head is fully inspected using a full inspection machine.
Take for example one of our small screws, the basic size of which is T10, M3. The process: punching - thread rolling - heat treatment - plating. The punch is used to form the head, which is the small cross-shaped or monogrammed recess used for screwing. Thread rolling is to form the threaded part. Heat treatment is used to harden the product and remove stress. Electroplating is to prevent the product from rusting.
As for some other processes. Milling: this process is generally used for smaller or more demanding screws, as the thread rolling process is done by extruding the metal material to produce plastic deformation, and the last turn of the thread may be deformed due to the lack of subsequent support, which may affect the flatness of the screw interface. In addition to electroplating and oxidation, blackening and so on, the purpose of this process is to prevent the product from rusting, generally this process is selected through the salt spray test, under the specified experimental environment and requirements, can pass the test, and the lowest cost program is the best choice.
Disc - annealing - pickling - wire drawing - tapping - rolling the teeth - heat treatment - plating - packaging
This is the complete process of a bolt production.
Coil: refers to the wire you buy
Annealing: the hardening of the wire itself. (This process is also important, nowadays high temperature spheroidal annealing furnaces are used)
Pickling: This is the process of washing away rust, impurities and so on from the surface of the wire.
Drawing: This is the process of drawing the wire to the diameter you need to produce the bolt.
Headed: the head of the bolt is extruded from the cold heading. (If the bolt is above M20, it needs to be red-beaten, that is, the head needs to be heated and then beaten, but the surface of the bolt is not very beautiful because of the oxide)
Thread rolling: the required pitch and shape of the teeth
Heat treatment: this process is important to determine the performance level of the bolt
Electroplating: the surface is treated to the required colour
Introduction to bolt strength classes
Strength grades are classified according to mechanical properties. According to the relevant standards, the bolt performance grade is divided into 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9 and more than 10 grades, of which 8.8 and above bolts made of low-carbon alloy steel or medium carbon steel and heat treatment (quenching, tempering), commonly known as high-strength bolts, the rest are commonly known as ordinary bolts. The bolt performance grade number has two parts consisting of numbers, which indicate the nominal tensile strength value of the bolt material and the flexural strength ratio. For example.MORE +
The first is the punching of the head, where the head of the screw is punched out of the wire and the wire is cut. The second is thread rolling, where two files are used to thwart the threads on top of the previous process.MORE +
Performance grades for hexagonal flange bolts
The bolt performance grade is composed of two numerical parts, which indicate the nominal tensile strength value and the flexural strength ratio of the bolt material.MORE +
What are the common automotive fasteners
Generally we use most of the fasteners belong to the type of general-purpose parts, its standard type is still quite high, the common fastener parts are the following 12 kinds:MORE +