Study And Manufacture Of PM Inserted Rocker Arm For JQ Engine

In a gas outfit of an automobile, the rocker arm insert and the valve rod form frictional mates that move back and forth, so their working conditions are complicated and bad. Having analyzed the failure-free working possibility of the main frictional mates in gas outfits of automobiles, it is the life of the said frictional mates that directly affects the reliability of the whole engine. As the rolling speed and compressing ration of engines increase, the working conditions of rocker arm insert get worse, thus the materials must be excellently wear-resistant and stable. Now, the PM inserts are widely used overseas. Using PM inserts can save energy and material. Moreover, they have many special properties that are very important to lowering noise, improving lubrication status and advancing the performance of the engine. However, we cannot produce this PM insert at home up to now. So, we do this work to help the domestic production of PM rocker arm inserts in our country and reduce their costs. In this paper, systemic experiments are performed on the compositions, processes, microstructures and properties of some high quality PM inserts. Main procedures such as mixing, compaction, sintering, re-compaction, re-sintering, heat-treatment, properties detection and mould design and so on are included in these experiments. After carefully compared and analyzed the results, the optimal composition is determined to be M2 plus 0.2%C and a 3-stage sintering process is selected ,which are 1050℃×1h, 1200℃×1.5h and 1240℃×0.25h respectively. The resulted microstructure is Ld'+A'+MC+ M6C, density not less than 8.0g/cm3 and hardness not less than HRC50. The effects of alloying elements, sintering process, microstructure and liquid phase sintering on properties of PM inserts are discussed too. The researching objects in the present work are those PM products with high strength, high density and high wear-resistance, so the conclusions are worthwhile for the development of high quality PM structural products in our country. Now, the achievement has been used in Chongqing Huafu Industry Co. One million and two hundred thousand PM inserts are produced each year in this company. These high quality inserts are sold to Ha'erbin Dongan Sanling Co. and Chongqing Changan Co. etc, and make RMB 18 million yuan a year for Huafu Co.