Pure dry goods! Ultra-detailed screw knowledge map

Pure dry goods! Ultra-detailed screw knowledge map

Terms relating to screws 

1. The difference between screws, nuts, nuts, bolts, screws, and studs: The standard statement is that there are no screws and nuts. Screws are commonly known, and those with external threads can be called "screws". The shape of the nut is usually hexagonal, and the inner hole is internally threaded, which is used to cooperate with the bolt to tighten the relevant parts. Nut is commonly known, the standard should be called "nut".

The head of the bolt is generally hexagonal and the shank is externally threaded. The screw is small, the head has a flat head, crosshead, etc., and the rod has an external thread. The stud should actually be called "double-headed stud", both ends have external threads, and the middle is generally a smooth rod. The long end of the thread is used to connect with the deep hole, and the short section is connected with the nut.

2. Common English expression: Screw / Bolt / Fastener (screw/screw) (bolt) (fastener)

3.Definition of thread:A thread is a shape that has a uniform spiral protrusion on the outer or inner surface of a solid.

Thread effect

1. Fastening and connection function: suitable for most screw products at this stage.

2. Transmission function (displacement function): For example, the micrometer used for QC inspection.

3. Sealing function: such as pipeline connection seal.

The history of the development of thread

  

Machine thread: during assembly, drill holes and tap teeth on the assembly. the tapped inner teeth are consistent with the outer teeth of the screw, and assembly is carried out with a small torque.

 

 

 

 

 

 

 

 

 

Self-tapping thread: during assembly, drill holes on the assembly first, and use large torque to assemble without tapping internal teeth.

 

 

 

 

 

 

 

 

 

Self-drilling thread: used directly on the assembly, screw drilling and tapping at one time.

 

 

 

 

 

 

 

 

 

Screw processing method

  

1.turning machining(Turning)    

To bring the material to its desired shape by removing the material

Advantages: high machining accuracy, no mold restrictions

Insufficient: high production cost and slow processing speed

2.Forging processing(Forging)    

The material is deformed by external force to achieve the desired shape.

Advantages: fast production speed, low cost, suitable for mass production

Inadequacy: Forming is limited by the mold, the mold cost of complex products is high.

 

3.cold heading

Is in the metal wire is not heated in the state, the use of mold with external force on its extrusion deformation process, cold heading process is only a kind of forging process.

Introduction of basic screw configuration

  

To understand screws and bolts, first know their types, features and functions:

A: Drive system

B: Head

C: joint part of tooth shape part

D: import and attack department

 

Mechanical tooth screw

 

 

 

 

 

 

 

 

Self-tapping screw

 

Triangle screw

 

 

 

 

 

 

 

 

 

 

 

Screw head type

Screw profile

Screw process flow

 

 

The general flow chart is as follows:

 

Disk element process

Refers to the original wire rod purchased by the raw material manufacturer. A wire rod mainly includes the following parameters: A, brand B, product name C, specification D, material E, furnace number or batch number F, quantity or weight. The main chemical components of carbon steel plate are: C, Mn, P, S, Si, Cu, Al, in which the lower the content of Cu and Al, the better.

 

 

 

 

 

 

 

 

Wire drawing process

In order to achieve the wire diameter we need (e. g. to 3.5mm draw wire).

 

 

 

 

 

 

 

 

Cold heading (heading) process

Through the interaction between the mold, to shape, first cut the wire, upsetting into screw blanks, forming the head, cross groove (or other head type) thread blank diameter and rod length, head rounded corners, etc.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

English Version (Can be designed according to customer needs, commonly used head type is P head, B head, F head, T head and other commonly used slot type has cross slot, slot, plum blossom slot, hexagon socket, etc.).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Teeth rubbing process

The cold-headed blank is rubbed out of the thread, and the tooth pattern is shaped by the interaction between the movable tooth plate and the fixed tooth plate.

 

 

 

 

 

 

 

 

 

Changes before and after rubbing teeth

 

 

 

 

 

 

 

 

Tooth rubbing machine

 

 

 

 

 

 

 

 

Tooth rubbing board (template)

 

 

 

 

 

 

 

 

Heat treatment process

1. Objective: To make the screw get higher hardness and strength after cold heading processing.

2. Function: realize the self-tapping and locking of metal, and improve the mechanical properties of metal parts, such as torsion resistance, tensile resistance and wear resistance. 3. Classification: A. Annealing:(700 ℃ x 4hr): Elongated tissue-regular polygon.

 

 

 

 

 

 

 

 

Cold working tissue morphology B. Carburizing heat treatment (adding carbon to metal parts to improve its surface hardness, for metal materials with low carbon content).

C. quenching and tempering heat treatment (no elements are added to the metal, and the internal structure of the metal is changed by the change of temperature to obtain better mechanical properties).

 

 

 

 

 

 

 

 

 

Plating process

The surface of the product after electroplating can present the desired color effect and surface oxidation resistance coating effect.