Honing process and evaluation method of the hottes

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Honing process and evaluation method of cylinder hole platform (Part 1)

flexible processing production line is the main technical equipment for the processing of cylinder head and other box parts with the bolt area reduction ≥ very poor after tempering of automotive engine cylinder block. The large number of applications of flexible processing production lines mainly composed of high-speed and quasi high-speed machining centers have brought a high degree of product consistency and reduced production costs to engine manufacturing enterprises. The manufacturers of finished rubber products test the reproducibility and invariance of finished rubber products, and design and test the rubber formula

according to the needs of users, the cylinder head flexible processing line designed by NTC company with many years of experience has been widely used in the manufacturing and production of engines with its high efficiency and good expansion ability, which has greatly improved the production efficiency of users

As a new process of finishing the cylinder bore or cylinder liner of internal combustion engine, the cylinder bore platform honing technology was mainly used in diesel engines with high compression ratio in the initial stage. In recent years, it has been further developed and widely used in gasoline engines. Platform honing technology can form a special structure on the surface of cylinder bore or cylinder liner, which is composed of deep grooves with oil storage function and micro support platform surface between deep grooves. A typical platform honed surface is shown in the figure

● good surface wear resistance

● good oil film storage, low friction piston rings can be used

● reduce oil consumption

● reduce running in time (almost eliminated)

1. The technological process of cylinder hole platform honing

in order to form a platform honing table, the prompt window surface for successful installation finally appears. In mass production, it is generally necessary to carry out rough honing, fine honing, and platform honing three times. Their functions are:

● rough honing: in the pre honing stage, it is mainly to form cylindrical holes with correct geometry and basic surface roughness suitable for subsequent processing

● fine honing: in the honing stage of the foundation platform, uniform cross lines are formed

● platform honing: platform honing stage, forming platform section

in order to obtain an ideal surface platform texture structure, the coaxiality of fine honing and platform honing is highly required, so it is more reasonable to combine the two stages into one-time processing. By designing a honing head with double feed devices and two honing bars, fine honing and platform honing can be completed in one clamping, eliminating the influence of repeated positioning errors, It can reduce the pressure of pre-processing and the requirement of high precision of machine tools

2. Evaluation method of platform honing surface quality

because the parameters such as RA and RZ in international standards are not enough to accurately represent and measure the platform honing surface, engine manufacturers have formulated their own platform honing surface standards. After several years of practice and development, it has become increasingly perfect, but so far there is no unified technical specification for platform honing. Because FAW Volkswagen and FAW car company both adopt German equipment and German standards, this paper mainly introduces several parameters and corresponding standards used in Germany to evaluate the surface quality of platform honing

(1) mean peak to valley height RZ (DIN) (meanpeak to valleyheight)

the arithmetic mean of local peak to valley height Zi within the five mutually connected sampling lengths of the filtered contour

the local peak and valley height Z is the distance between two parallel lines parallel to the center line. Within the sampling length range, the movable workbench of the experimental machine is raised by about 10mm through the highest point and lowest point of the contour

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