Camshaft modification and production technology

Camshaft modification and production technology
Refit
In order to improve the power of the engine, some refit shops have refitted the camshaft of the engine. Among them, the high-angle camshaft camshaft (Hi-CAM) is a common modification method. This modification operation is not complicated, but because some modification personnel have insufficient understanding of the working angle and working principle of the cam on the camshaft, the effect of the modification is not obvious and even the performance of the engine is deteriorated.
The high-angle camshaft is relative to the normal camshaft's cam working angle of about 240°. The cam working angle of the high-angle camshaft can usually reach more than 280°. The large-angle camshaft can extend the opening time of the valve, increase the lift of the valve, enable the intake valve and exhaust valve to open early and close late, and allow more air to enter the cylinder to increase the power of the engine at medium and high speeds. Output. For civilian vehicles, a camshaft with a cam working angle below 278° should be selected when refitting, because a camshaft with a working angle greater than 278° will greatly increase the valve overlap angle and increase the power of the engine at high speeds. However, the engine At low speeds, due to poor air tightness of the cylinders, severe idling jitter or even flameout will occur. Such vehicles cannot adapt to daily use and can only be used for competition purposes.
Production technology
The camshaft is one of the key parts of the engine. The hardness and the depth of the white mouth layer of the camshaft are the key technical indicators that determine the service life of the camshaft and the efficiency of the engine. On the premise of ensuring that the cam has a sufficiently high hardness and a fairly deep white mouth layer, it should also be considered that there is no higher carbide in the journal, so that it has better cutting performance.
The main methods of producing camshafts at home and abroad are: after the steel forging blank is cut, the top part of the cam is high-frequency quenched to form a martensite layer. At the end of the 1970s, Germany and France successively developed a new argon arc remelting process for camshafts; there are also hardenable cast iron camshafts mainly in the United States; chilled cast iron camshafts mainly in Japan and France; and cams The production process of casting surface alloying with Cr-Mn-Mo alloy coating for parts.