The assembly camshaft is a new type of internal combustion engine parts developed in the past 20 years, which adapts to the development trend of light weight, high performance, low emission and low cost of the automobile industry. At present, more and more car manufacturers in the world will be equipped with camshaft for high-performance engine, the improvement of its production process to promote the continuous development of China's auto industry has important practical significance.
Process of Traditional Integral Camshaft and Its Disadvantages
The traditional integral camshaft is cast or forged rough cutting finished products, individual direct use of bar processing into parts. In order to ensure the accuracy of parts processing, the overall casting or forging camshaft blanks must be supplemented by a large number of cutting (using cars, milling, grinding, polishing) and surface hardening, carburizing, nitriding and other intensive treatment.
The main drawbacks of traditional integral camshaft machining are as follows:
(1) the engine work process, the cam requires wear resistance, resistance to stamping, pitting resistance; journal requirements sliding performance; mandrel requires rigidity, bending, reverse performance. The overall camshaft is difficult to meet the above requirements at the same time, its material utilization is also unreasonable.
(2) it is difficult to create a cam profile, compact camshaft.
(3) need a lot of processing processes, machine tools, knives, fixtures and personnel, long hours, covers an area of large, high cost.
(4) on the cam surface wear and tear treatment is easy to deformation and need to straighten.
(5) rough cam profile is large and uneven, difficult processing, affecting the quality of parts processing.
(6) make a lot of material into waste, and difficult to reduce product costs.
(7) low production efficiency, material and energy consumption, production automation level is low.
Assembly camshaft technology advantage
The assembly camshaft is also called composite axle, which consists of steel pipe (mandrel), journal (bearing ring), cam, pump peach, plug and tail pieces and other parts, respectively, material optimization and lean processing, And then assembled into camshaft.
The assembly camshaft mandrel is generally made of cold drawn seamless steel pipe, the cam is made of carbon steel or powder sintered material, carbon steel cam can be precision plastic forming, and high frequency quenching or carburizing treatment.
The cam assembly accuracy of the mounted camshaft (Cmk = 1.67) generally achieves the following levels:
Angle: ± 0.5 ° (rough forging cam), ± 0.25 ° (machined cam).
Axial size: ± 0.1mm.
Load: torque> 150N · m, axial load> 10kN.
After the assembly connection, the parts are finished according to the product requirements.
The assembled camshaft has the following technical advantages over traditional camshafts:
(1) can achieve flexible design, flexible production and agile manufacturing. In the assembly process, can achieve cam phase angle and axial position of the free adjustment and correction, is conducive to the design and manufacture of new products, shorten the R & D and manufacturing cycle.
(2) is conducive to material separation optimization and camshaft structure selection. According to the valve body on the cam shaft of the various parts of the performance requirements are different, a reasonable choice of cam, journal and mandrel material to ensure its quality requirements.
(3) the use of nearly net forming process forming cam, can significantly reduce manufacturing costs. According to the material and shape requirements, the use of cold precision plastic forming, powder metallurgy sintering, precision casting and other process forming cam, reducing the cam cutting process, saving time and reduce costs.
(4) hollow tube mandrel, cam material optimization and precision forming technology applications, can reduce the overall quality of the camshaft by 20% to 40%, saving more than 30% of the material.
(5) can be used for different parts of the most appropriate heat treatment technology and surface strengthening technology, thereby greatly improving the camshaft manufacturing accuracy, product quality and service life.
(6) All parts of the camshaft are machined and assembled to reduce assembly costs and assembly costs.
(7) to improve the overall stiffness of the camshaft. Its dynamic torque up to 800 ~ 1 000N · m, and can reduce the friction, to withstand the higher impact of the valve load.
(8) cam working surface according to product performance requirements, any design choice. Near net forming technology can be used for different curvature of the cam processing, is conducive to the development of new engine applications.
(9) can significantly save camshaft metal processing equipment and working hours, split parts and equipment miniaturization also reduces the equipment investment and site area.
(10) The arrangement of the cams on the mandrel can be made more compact and is superior to the machining of the multi-valve
(11) parts of the processing, can greatly improve the production automation and intensive degree.