摘要活塞是发动机中的重要零件之一。活塞组由活塞、活塞环及活塞销组成，活塞组在连杆的带动下，在气缸内作着往复运动，形成不断变化的气缸容积，在气阀的等部件的配合下，实现制冷剂气体的吸入、压缩、排出与膨胀过程。它在工作时承受发动机气缸内高温气体的压力，并通过活塞销、连杆将压力传给曲轴。因此活塞是在高温、高压和连续变负载下工作的。46940

本文主要论述了活塞的加工工艺及其夹具设计。活塞的尺寸精度、形状精度以及位置精度的要求都非常高，发动机活塞的材料为铝合金，它的导热性好、重量轻、惯性力小，并且有较好的切削加工性。铝活塞的毛坯采用金属模浇铸，毛坯的精度较高，活塞销孔也能铸出，因此机械加工余量可以相应地减少。根据活塞工作条件、结构特点以及技术要求等因素，我设计了两套工艺方案，选择最好的方式制定了活塞加工的工艺规程，并设计了两套关键工序中专用设备所使用的专用夹具。

毕业论文关键词   活塞；工艺；夹具；工序卡；精度

Abstract

The connecting rod is one of the main driving medium of diesel engine, its status is obvious in engine. It is the main accessory of movement which can transmit the engine’s power. It can do the complex movement in the plane, the small connecting rod run the up and down with the piston；the big connecting rod is rolling in high speed with crankshaft; the connecting rod’s do the complex swing with the big and small connecting rod’s movement. Beside it is stood by the reciprocating inertia force, also under great pressure and gas pressure, the gas pressure and inertia synthesis alternating load, formed under the requires connecting rod fatigue resistance, impact resistance, and possess enough intensity, stiffness and good toughness. 

This paper mainly discusses the processing technology and fixture design of piston.Piston dimension precision, the accuracy requirement of the shape and position precision is very high, engine piston material is aluminium alloy, its thermal conductivity, light weight, small inertia force, and has better cutting processability . Aluminium piston blank by metal mould casting, the precision of the blank is higher, the piston pin hole can be cast out, so the machining allowance can be reduced accordingly. According to the working conditions of the piston, structure features and technical requirements, design the two sets of process scheme, selection of the best ways to make the piston machining process planning, key process and designed two sets of special equipment used by special fixture.

Key words :  Piston;  process;  fixture;  operation flow chart;  precision

目  录

1. 绪 论       6

1.1 课题研究背景、目的、意义  

1.1.1 汽车发动机活塞研究的背景和意义  

1.1.2   汽车发动机活塞研究的意义 

   1.2 国内外活塞加工工艺的发展、现状及趋势 

1.1.3 活塞加工工艺的发展 

1.1.4 活塞加工工艺的现状 

1.1.5 活塞加工工艺的趋势 

1.1.6 活塞加工工艺存在的问题 

2. 被加工零件的工艺特点 ... 2

2.1  活塞的作用 . 2

2.2  活塞的特点 . 2

2.3  活塞的主要技术条件分析 3

   2.3.1  活塞裙部外圆与气缸的配合