Fastener threads play a vital role in the fastening of parts.For the Railway Fastening System Manufacturer, many people may have various parts of fasteners, such as: screws, nuts, bolts and rivets. What do you know, and how much do you know about the thread? In the use of fastener threads, the choice of fine and coarse teeth is the most difficult to make a decision. China Screw Spike Supplier's understanding of fastener threads, come Share the introduction about threads and the selection of related fine and coarse threads.
Definition of fastener threads
Thread is a shape with a uniform spiral line on the outer or inner surface of a solid.
Fastener thread action
1. Fastening and connection: suitable for most screw products at this stage.
2. Transmission effect: such as a micrometer used for QC inspection.
3. Sealing effect: such as sealing the connection of the pipeline.
Development history of fastener threads
Machine thread: During assembly, drill and tap on the assembly first. The inner teeth and the outer teeth of the screw have the same specifications. Use a smaller torque for assembly.
Self-tapping threads: first drill holes in the assembly when assembling, without tapping the internal teeth, using a larger torque for assembly.
Self-drilling thread: used directly on the assembly, screw drilling and tapping once.
What is fine thread? What is coarse thread? How to choose coarse and fine thread?
To what extent can a fine thread be called a fine thread? We may wish to define it this way. The so-called coarse thread can be defined as a standard thread; while the fine thread is relatively coarse, at the same nominal diameter, The number of teeth per inch is different, that is, the pitch is different, the pitch of coarse teeth is large, and the pitch of fine teeth is small. That is to say, for 1 / 2-13 and 1 / 2-20 specifications, the former is coarse teeth and the latter is fine teeth.
Since there are two different thread specifications for the same nominal diameter, how to choose coarse and fine threads?
Definition: The so-called coarse tooth actually refers to the standard thread. Without special instructions, the fasteners such as stainless steel screws that we generally buy are coarse teeth.
The characteristics of coarse thread: it has high strength, good interchangeability, and there are standards to be compared. Generally speaking, coarse teeth should be the best choice;
Compared with fine-threaded threads: due to the large pitch, the thread rising angle is also large, and the self-locking performance is poor. Anti-loose washers and self-locking devices need to be installed in the vibration environment; the advantage is that it is easy to disassemble and complete with standard accessories Easy to interchange;
Definition: Fine teeth and coarse teeth are just the opposite.They are specified to supplement the special use requirements that coarse threads cannot meet. Fine threads also have a pitch series, and the pitch of fine teeth is smaller.
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