Related terms for screws
1. The difference between screws, nuts, nuts, bolts, screws, and studs: the standard saying is that there are no screws and nuts. Screws are a common name, and those with external threads can be called "screws". The shape of the nut is usually hexagonal, and the inner hole is an internal thread, which is used to cooperate with the bolt and tighten the related parts. Nut is a common name, and the standard should be called "nut".
The head of the bolt is generally hexagonal, and the shank has an external thread. The screw is small, the head has a flat head, a cross head, etc., and the shank has an external thread. Studs should actually be called "double-ended studs". Both ends have external threads, and the middle is usually a polished rod. The long end of the thread is used to connect with the deep hole, and the short end is connected with the nut.
2. Common English representation: Screw / Bolt / Fastener (screw/screw) (bolt) (fastener)
3. Definition of thread: thread is a shape with uniform helical protrusions on the outer or inner surface of a solid.
Thread action
1. Fastening and connecting function: suitable for most screw products at this stage.
2. Transmission effect (displacement effect): such as the micrometer used by QC to check the size.
3. Sealing function: such as the connection sealing of pipelines.
History of thread development
Machine thread: When assembling, first drill and tap the assembly, the internal thread to be tapped is the same as the external thread of the screw, and assembled with a small torque.
Self-tapping thread: When assembling, drill holes on the assembly first, without tapping the inner thread, and use a larger torque for assembly.
Self-drilling thread: It is used directly on the assembly, and the screw is drilled and tapped at one time.
Screw processing method
1. Turning (Turning)
Make the material into the desired shape by removing the material
Advantages: high machining accuracy, no mold restrictions
Disadvantages: high production cost, slow processing speed
2. Forging
Deform the material by extruding it to achieve the desired shape
Advantages: fast production speed, low cost, suitable for mass production
Insufficient: Forming is limited by the mold, and the mold cost for complex products is high
3. Cold heading
It is the process of extruding and deforming the metal wire with the help of external force under the condition that the metal wire is not heated. The cold heading process is only a kind of forging process.
Introduction to the basic configuration of screws
To understand screws and bolts, you must first know their types, characteristics and functions:
A: drive system
B: head
C: The junction of the teeth
D: Import and attack department
Machine screw
self tapping screw
Triangular tooth screw
screw head type
screw profile
Screw process
The general flow chart is as follows:
Disk unit process
Refers to the original wire rod purchased by the raw material manufacturer. A coil unit mainly includes the following parameters:
A. Brand
B. Product name
C. Specifications
D. Material
E. Furnace number or batch number
F. Quantity or weight.
The main chemical components of carbon steel disk elements are: C, Mn, P, S, Si, Cu, Al, and the lower the content of Cu and Al, the better.
Drawing process
In order to achieve the wire diameter we need (such as to 3.5mm draw wire).
Cold heading (heading) process
Through the interaction between the moulds, it is formed. Firstly, the wire is cut off, and then upset into a screw blank to form the head, cross groove (or other head shape) thread blank diameter and rod length, and rounded corners under the head, etc.
Explanation: It can be designed according to the needs of customers. Commonly used head types are P head, B head, F head, T head, etc. Commonly used groove types include cross groove, slotted groove, plum blossom groove, hexagonal groove, etc.
Tooth rubbing process
The cold-headed blank is twisted out of the thread, and the tooth pattern is formed through the interaction of the movable tooth plate and the fixed tooth plate.
picture
Changes before and after tooth rubbing
tooth rubbing machine
Rub board (template)
heat treatment process
1. Purpose: To make the screw get higher hardness and strength after cold heading.
2. Function: Realize the self-tapping locking of metal, improve the mechanical properties of metal parts, such as torsion resistance, tensile resistance and wear resistance.
3. Classification: A. Annealing: (700°C x 4hr): elongated structure - regular polygon.
cold working structure
B. Carburizing heat treatment (adding carbon elements to metal parts to improve their surface hardness, for metal materials with low carbon content).
C. Quenching and tempering heat treatment (do not add elements to the metal, change the internal structure of the metal by changing the temperature to obtain better mechanical properties).
Electroplating process
The surface of the product after electroplating can present the required color effect and surface anti-oxidation coating effect.
