1、 Eccentric shaft heat treatment and mechanical properties research Abstract This paper focuses on the eccentric shaft material 20Cr heat treatment (carburizing, quenching, a tempering, and second tempering) process and its main mechanical properties, high hardness is main properties. Analysis how Ca
2、rburizing temperature ,time an, cooling method ,direct quenching ,a quenching, secondary quenching and other factors defect on the mechanical properties and organization from the theory. After confirmed 20Crs eccentric shafts best heat treatment process parameters and the best carburizing quench way
3、 (salt bath, direct quenching, low temperature tempering), analysis and detect the infiltration depth of the carburized, microstructure and mechanical parts. Key words: eccentric shaft, heat treatment, carburizing, carburizing temperature, cooling method, carburized layer Chapter The introduction 1.
4、1 Preface The role of the eccentric shaft is to adjust the center distance between convenient, eccentric shaft is usually used in the V-belt drive in the planar linkage. Normal shaft can only drive the work piece, but the eccentric shaft, not only can pass the rotation, also can pass the revolution.
5、 Now the U.S. compressor giant Copeland is using eccentric shaft to drive the vortex of revolution and efficient compression formulations fast. Eccentric shaft is an important transmission part of electric tool electricity hammer. Install the eccentric shaft and let it running to dead spots position
6、 will not produce locks by inertia effect. The most common example is: household sewing machine feet moving wheel of the operation. Rotating eccentric shaft driven machine is the indispensable machinery parts. Schematic diagram of the eccentric shaft 1.2 The purpose of the eccentric shaft and perfor
7、mance requirements Eccentric shaft is widely used in mining, electromechanical, water conservancy, etc. With the increase in the production of these products, and consumer groups asked the continuous improvement of the quality of the eccentric shaft is imminent, exported 400 million air-conditioning
8、 compressor units by 2008, air exports increased by 27% than in 2005. Air conditioning compressor is exported to South East Asia mainly. Because the eccentric shaft under enormous impact load at work, and the hammer of the working conditions, many dust, parts wear easily. Therefore, the surface of t
9、he eccentric shaft required high hardness, wear resistance and fatigue strength, while the core part has a certain strength and good plasticity, toughness and other special properties. 1.3 The situation at home and abroad 1.3.1 Domestic Research Trends Heat treatment has a long history in China, wit
10、h other scientific and technological development, heat treatment technology develop the rapidly . (1) Namely, the continuous improvement of experimental methods and techniques. Understanding the relationship between the changes in the organization of metal rules and microstructure, develop new heat
11、treatment process. (2) In the basic theoretical aspects continuously make achievements. (3) The research of surface chemistry, develop all kinds of surface protective heat treatment and surface strengthening heat treatment. (4) Other new energy, new technology development, make heat treatment proces
12、s become complex process. Recent sessions of the International Conference on Materials and Heat Treatment predicts the development of ancient and modern metal heat treatment process and heating equipment t, the basic view is: (1) heating equipment In the heating device to more development of electri
13、c furnace, especially the development of induction furnace, reducing fuel furnace. Most of the furnace and heat treatment equipment to achieve automation and digital control, not only can reduce the labor force, but the premise is to improve the quality of heat treatment. (2) Heat treatment process
14、a. Improved conventional heating process. Air heating will be vacuum heated, controlled atmosphere or protective atmosphere heating, as well as vacuum and controlled atmosphere heating joint will replace air heating. With the vacuum technology progress, vacuum heat treatment towards furnace temperat
15、ure increased and the automation. Induction heating treatment, tend to increasing power and frequency range direction. b. expansion of the surface heat treatment and various types of chemical treatment instead of the whole heat treatment. 1.3.2 Heat treatment equipment and heat treatment technology
16、abroad status ( ) in the early 1970s, American Society for Metals (ASM), British Wolf Morrison heat treatment center (Wolfson Heat Treatment Center) and the former Yugoslavia (now Croatia) have established the material and Heat Treatment, did it may, according to the database of mechanical performan
17、ce requirements after heat-treatment of computer-aided material selection, or known material and Heat Treatment process foresee the organization and performance last. Then Europe, Japan and other advanced industrial countries to develop computer auto-calculating on all kinds of heat treatment proces
18、s control technology, began the process parameters under computer control, and analog control technology in production gained in application. The international well-known anufacturers of many successive and cycle type heat treatment line adopted by programmable Controller (Programable) or microproce
19、ssor Controller of single control or group control. Foreign heat treatment factory attaches great importance to the cooling heating process. According to the product technology and process requirement, can undertake rapid cooling, oil quenching cooling, disposable gas quenching cooling, etc. By gas
20、quenching way before the quenching cooling nitrogen and helium gas, and now the use of air jet, the strong in fast speed, quenching cooling after only extremely thin surface oxidation, are pale, parts, and still beautiful color saved a great deal of nitrogen and inert gas, so that treatment costs wi
21、ll decline further. Vacuum low-pressure carburizing combined with high-pressure gas quenching is an advanced carburizing today, it has carburizing speed, excellent carbide organization ,quenching cracking and little deformation, saving energy and carburizing agent raw materials, carburized parts sur
22、face quality is good, be helpful for environmental protection etc. ( ) heat treatment equipment: The trend of foreign heat treatment furnace development: (1) stove based on the power is increasing, oil for heat treatment furnace ratio decreasing. (2) To product surface quality request more strictly
23、controlled atmosphere heat treatment furnace, this occupies an important position still. (3) Lining tends to use of lightweight materials, the application in resistance furnace with heat-resistant component and nonmetallic furnace the proportion of heating elements increase gradually. (4) The microc
24、omputer and PLC accelerates the development of heat, and have with the other automation line of automatic heat treatment process of trend. 1.4 eccentric shaft failure forms and preventing measures Shaft loading: fatigue, impact, tensile, compression, bending, twisting, cutting, wear, surface changes
25、, size changes, etching, corrosion and other failure modes. (1) eccentric shaft under heavy load at work, subject to bending stress, wear and tear in the neck, by the main have occurred wear fracture and axial crack two circumstances parts (2) axial crack, axial crack is eccentric shaft parts common
26、 failure form, this crack except material adverse outside, main is caused by excessive heat surface tension stress caused by its quench-hardening ability, due to merger part weeks than axial tensile stress surface , and material surface tensile stress of lateral performance under longitudinal, preve
27、nt such hardening layer, and promptly tempering. (3) Axis failure form: There are insufficient due to fatigue resulting fatigue fracture, static strength due to lack of plastic deformation or brittle fracture, wear, and exceed the allowable range of deformation and vibration. (4) axial fracture is mainly reverse fatigue fracture.
