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Application principle of spring contact finger


Release time:

2022-07-25

Compared with traditional mechanical switches, electrical sensors that use spring contact fingers to build capacitive sensors are a more robust alternative plan. Some things cannot be directly provided with a printed circuit board under the cover, nor can the printed circuit board be connected to the device housing. This use includes home appliances such as stoves, washing machines, refrigerators, and microwave ovens, as well as various vehicle electronic equipment such as radios, TV tuners, control panels, and seat occupant detection systems, so, let's understand the application principle of the spring touch finger together!

Application principle of spring contact finger

Compared with traditional mechanical switches, electrical sensors that use spring contact fingers to build capacitive sensors are a more robust alternative plan. Some things cannot be directly provided with a printed circuit board under the cover, nor can the printed circuit board be connected to the device housing. This use includes home appliances such as stoves, washing machines, refrigerators, and microwave ovens, as well as various vehicle electronic equipment such as radios, TV tuners, control panels, and seat occupant detection systems, so, let's understand the application principle of the spring touch finger together!

弹簧触指

Spring contact finger sensor-can replace the solid conductivity sensor. This allows the PCB to be oriented away from the cover, providing a reliable sensor connection under operating conditions of high vibration or sharp temperature changes. In addition, the spring can also provide backlighting, mechanical and capacitor button fusion, and other functions.


Product Materials


Qin carbon steel wire, low carbon steel wire, high carbon steel wire, manganese steel wire, nickel wire, 60SizMNA, spring stainless steel wire and other materials.


Appearance plating


Nickel, nickel-free white k plating, directly above gold, bottom gold, silver, bronze, silver, etc.


Selection specifications


Spring touch button products provide the following parameters: 1. Diameter of round metal contact piece. 2. Spring wire diameter. 3. Spring height. 4. Number of spring coils. 5. Outer diameter of spring. f. Hollow contact button when required to provide inner circle diameter.


The principle of spring contact finger is as follows:


There are many contacts, and each coil is a contact. That is, many circuits are connected in parallel. The more contact points, the more turns, the smaller the contact resistance, the more shunts, and the smaller the current flowing through each turn. The number of turns is large, the current distribution is uniform, the heat dissipation is good, the contact force value range is large, and the contact force value range is wide. Under the vibration environment, the contact with a resistor can be kept basically constant. Based on the original spring contact finger, there are different shapes of touch fingers, single-sided contact, double-sided contact, round surface contact, etc. The contact resistance of each coil spring is 4-5 micro ohms, take 50 coil contacts as an example, the resistance is 0.1 micro-ohms, the resistance is small, and the heating loss is also small.


Beryllium bronze is hard and powerful, the strength of zirconium and copper is more suitable, the contact friction is less than half of the friction of the plum contact, especially the high-current contact 3150/4000a contacts 82 contacts, the pressure is large, the circuit breaker swings and The jitter torque is large and difficult, but the spring contact does not require a lot of operating force, the spring contact finger is silver-plated, due to the large contact pressure and frequent contact, the wear and peeling of the silver plating layer will quickly corrode the anode copper, lose excellent conductivity, and threaten the safety of power grid operation. The existing new technology is to apply the corrosion behavior of the contact substrate copper under current to prepare the silver-graphene composite coating to improve the corrosion resistance and wear resistance of the contact material, because of high hardness, excellent wear resistance and corrosion resistance, and high cost.


With a spring contact finger, due to low working pressure, many contact knowledge points, small contact wear and 10000 back swings, in addition, small outer diameter, large current carrying capacity, strong short-circuit calculation ability and uniform electric field distribution of contact system, many people are worried about the application of spring contact finger in withdrawable circuit breakers, but in fact, by improving accuracy, the positioning of positioning pins is accelerated, it can fully ensure the requirement of spring contact finger/-1mm, the spring does not have to be round, and other shapes can be used for many purposes, such as rectangular contacts for circuit breakers, single-sided contacts for low-voltage lead-out, etc.


Scope of application


Induction cooker, light stove, electric heater, disinfection cabinet, range hood, water heater, heater, vegetable washing machine, cash counter, massager, electric oven, electronic wine cabinet, water dispenser and other series are suitable for contact with small household appliances.


Precautions


Spring products are commonly used hardware parts in various professions. Screws and nuts that are different from screws and nut mechanical parts are sold in all hardware stores, but there are few springs. For example, in the two manufacturers, the appearance of the product is slightly different, but the required spring size, compression elasticity, tension and torsion are completely different. So springs don't have a lot of stock.


The above introduction is the application principle of spring touch finger, if you need to know more, you can contact us at any time!


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