1. Basic introduction
Crimping is an important process in which raw materials (terminals, wires and sealing rings) are combined with copper wires and terminals through the jaws of crimping die to produce wiring harness components (circuits). Crimping is a process in which pressure is applied to the contact area of the conductor and terminal to make it form and achieve tight connection.
Crimping is cold pressing technology, the earliest origin can be traced back to around 1940. The principle is to complete the crimping of metal wires and pins with the help of wire pliers or wire tools. Good air tightness, corrosion resistance, very reliable. Reliable data, signal and power transmission.
2. Purpose of crimping terminals
Provide non-detachable, long time reliable electrical and mechanical connections between crimping terminals and conductors. Crimping connection has the advantages of compact structure, strong connection, reliable seismic operation through special tools. Crimping provides the maximum possible connection density, i.e. the maximum number of connections per unit area, compared to normal screw connections. Pressing should be convenient for production and processing.
In the process of wire crimping, the crimping of core wire part and insulation part, core wire crimping and insulation skin crimping have certain differences, core wire crimping to ensure a good connection between the terminal and the wire, insulation skin crimping is to reduce vibration and move the core wire.
Crimping is divided into single - wire crimping, double - wire crimping, multi - wire crimping.
In the process of crimping, the conductor is squeezed by the casing and deformed in both longitude and latitude directions, forming cold welding. The original oxide film on the surface of the conductor and the casing is deformed and broken, and the pure metal surface of the conductor and the terminal casing is fully in close contact. During the extrusion and deformation, the micro movement of the metal surface can be observed under the microscope to integrate and adhere to each other.
Common term for crimping
Terminal crimping tool
Check the crimping quality of terminals
The quality of terminal crimping is judged from the following aspects: appearance inspection, crimping height measurement, crimping profile analysis and crimping holding force measurement. Now we mainly look at the requirements of appearance inspection.
Appearance check mainly includes four aspects, namely conductor layer, insulation layer, crimping bell and terminal material head position. Requirements for each section are as follows:
Conductor end requirements:
A. The conductor end should be flush with the top of the conductor crimping area, no more than 1mm above the top of the crimping area (area A in the figure)
B. The part of the conductor that exceeds the conductor crimping area must not impede the matching and locking function of the terminal
C. If the terminal pair is equipped with a family SEAL (preassembled in the connector), the length of the conductor at the top of the conductor crimping area is not greater than 0.5mm
Insulation layer top requirements:
The top of the insulation layer must be visible in the area between the conductor crimping area and the insulation crimping area (area B in the figure).
Requirements for crimping bell mouth at both ends:
A. The rear end of the conductor crimping area shall be provided with a bell-shaped structure. The length and size of the bell-shaped structure shall be determined according to the wire diameter.
B. The maximum allowable value of the front end of the conductor crimping area is the same as that of the back end.
End cutting protrusion (material head) Requirements:
A. The material end must be visible to ensure that the terminal is not damaged.
B. The material head should not affect the normal insertion and matching of terminals into plastic cases.
C. The maximum length of the head should not exceed 0.5mm. For connectors using family SEAL, the maximum length of the head should not exceed 0.3mm. The head should not damage the sealing ring.
Good crimping:
1. Crimping should ensure that the terminal can press at least 1/2 of the circumference of the insulation skin of the wire.
2. After crimping, the terminal claws should support each other and contact each other at least.
3. The terminal claw can Pierce the insulator but cannot Pierce the insulation skin and contact the conductor.
