Piston working conditions

Dongyi is here to let everyone know how harsh the working environment of the piston is. The main function of the piston is to withstand gas pressure and transmit it to the connecting rod through the piston pin to drive the crankshaft to rotate. The top of the piston is also a component of the compression chamber.

Working conditions

The piston can work under the conditions of high temperature, high pressure, high speed and poor lubrication. It can be said that the working conditions of the piston are very bad. The piston is in direct contact with the high-temperature gas, which leads to serious heating, and because the piston's heat dissipation conditions are extremely poor, the rapid heat dissipation is not achieved when the piston is working, which makes the temperature very high, the top is as high as 600~700K, and the temperature distribution is very uneven; The top of the piston bears great gas pressure, especially the maximum working stroke pressure, which makes the piston produce an impact and bear the effect of side pressure; the piston reciprocates at a high speed (8~12m/s) in the cylinder, and The speed is constantly changing, which produces a large inertial force, which makes the piston subject to a large additional load. Pistons working under such harsh conditions will deform and accelerate wear, as well as additional load and thermal stress.

Require

(1) It must have sufficient rigidity and strength, and reliable force transmission.
(2) Good thermal conductivity, high pressure resistance, high temperature resistance, and wear resistance.
(3) The mass is small and the weight is light, and the reciprocating inertia force is minimized as much as possible. Aluminum alloy materials basically meet the above requirements. Therefore, pistons generally use high-strength aluminum alloys, but high-grade cast iron, heat-resistant steel, and 3Cr13 are used in some high-pressure compressors.

Material requirements

(1) The piston body is generally made of high-strength aluminum alloy, high-grade cast iron, heat-resistant steel, and 3Cr13. Be applicable 
(2) Piston compression nuts are generally made of copper, No. 45 steel, 38CrMoALA, 41CrMoALA. Can be good
(3) Piston rods and piston pins are generally made of No. 45 steel and 3Cr13 through high frequency quenching treatment: 38CrMoALA and 41CrMoALA through low temperature nitriding treatment. PT