A thread welded integral forged steel piston

Abstract

The invention provides an engine piston, comprising a forged piston head and a forged piston skirt, the piston head and the piston skirt are fixedly connected together, and a closed cooling oil is formed between the piston head and the piston skirt The cooling oil cavity is communicated with the outside through the oil inlet and outlet holes. The ring grooves of the piston are all set on the piston skirt, including two air ring grooves above and one oil ring groove below; On the piston skirt, the upper end of the pin seat and the lower end of the piston head are connected together by threads; part or all of the outer circle of the upper end of the piston head forms an interference fit with the inner cavity of the upper end of the fire land of the piston skirt; The top surface has a single-sided weld.

Description

technical field [0001] The invention relates to a piston, in particular to a thread welded integral forged steel piston. Background technique [0002] The piston is the "heart" of the automobile engine, which bears alternating mechanical loads and thermal loads, and is one of the key components in the engine with the worst working conditions. The function of the piston is to withstand the gas pressure and transmit it to the connecting rod through the piston pin to drive the crankshaft to rotate. [0003] In the past ten years, engine design and manufacturing technology have been rapidly improved, especially diesel engines are developing towards high power and high load, the degree of strengthening has been continuously improved, and the explosive power has exceeded 20MPa. Although the piston has the advantage of light weight, the aluminum alloy material can only work stably at 350°C. Although various strengthening measures have been taken, such as: the first ring groove is ...

AI Technical Summary

Problems solved by technology

To improve the crack resistance of the combustion chamber, but the aluminum piston is still difficult to meet the engine requirements of Euro IV and Euro V standards

So now many companies are choosing steel materials to replace aluminum alloy materials, especially the development of forged steel piston materials has indicated the current direction of piston development, so aluminum materials have gradually been unable to meet the requirements of high power, high strength, and low emissions of engines.

For this reason, domestic and foreign piston design manufacturers are committed to the design and development of new pistons with high reliability and meeting the economical and emission requirements, such as liquid die forging ceramic fiber structure pistons, pendulum hinged pistons with steel top and aluminum skirt structures, cast iron Pistons, etc., the above structures have certain shortcomings, such as liquid forged ceramic fiber structure aluminum pistons have high requirements for blank forming technology, especially ceramic fiber structures, which must be formed under high pressure; the piston head of the pendulum hinge structure piston and the piston The skirt is processed and manufactured separately. Due to the large difference in wall thickness of the piston skirt, the casting rejection rate is high, which increases the cost, and it is difficult to form a closed oil cavity, and the cooling effect of the piston is poor. At the same time, because a longer piston pin is required for connection, the overall The weight has also increased, the cast iron piston pollutes the environment during the manufacturing process, the structure of the internal cooling oil chamber is difficult to realize, and the weight of the piston is difficult to control

[0004] In the existing technology, the forged piston head and the forged piston skirt are welded together by friction welding to manufacture the piston. This manufacturing method causes the weld seam inside the closed oil chamber to be unable to be cleaned. There are hard particles falling off, which increases the risk of engine scuffing

Welding defects are prone to occur when friction welding the piston head and piston skirt, which will lead to the separation of the piston head and piston skirt during use, resulting in engine damage or even the scrapping of the entire locomotive

In addition, the investment of friction welding is huge, which wastes energy

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