机械加工机械类外文翻译中英文翻译Word格式文档下载.docx

1、The fluid characteristics and condition of use determine the coolant action of the cutting fluid, which improves the heat transfer at the shear zone between the cutting edge, work piece, and cutting fluid. The properties of the coolant in this case must include a high heat capacity to carry away hea

2、t and good thermal conductivity to absorb the heat from the cutting region. The water-based coolant emulsion with its excellent high heat capacity is able to reduce tool wear 44.Cutting Fluid as a Lubricant:The purpose is to reduce friction between the cutting edge, rake face and the work piece mate

3、rial or reducing the cutting forces （tangential component）. As the friction drops the heat generated isdropped. As a result, the cutting tool wear rate is reduced and the surface finish is improved.Cutting Fluid PropertiesFree of perceivable odorPreserve clarity throughout lifeKind and unirritated t

4、o skin and eyes.Corrosion protection to the machine parts and work piece.Cost effective in terms off tool life, safety, dilution ratio, and fluid life. 15.1.1 Cutting Fluid TypesThere are two major categories of cutting fluidsNeat Cutting OilsNeat cutting oils are poor in their coolant characteristi

5、cs but have an excellent lubricity. They are applied by flooding the work area by a pump and re-circulated through a filter, tank and nozzles. This type is not diluted by water, and may contain lubricity and extreme-pressure additives to enhance their cutting performance properties. The usage of thi

6、s type has been declining for their poor cooling ability, causing fire risk, proven to cause health and safety risk to the operator 1. Water Based or Water Soluble Cutting FluidsThis group is subdivided into three categories:1. Emulsion mineral soluble white-milky color as a result of emulsion of oi

7、l in water. Contain from 40%-80% mineral oil and an emulsifying agent beside corrosion inhibitors, beside biocide to inhibit the bacteria growth.2. Micro emulsion semi-synthetic invented in 1980s, has less oil concentration and/or higher emulsifier ratio 10%-40% oil. Due to the high levels of emulsi

8、fier the oil droplet size in the fluid are smaller which make the fluid more translucent and easy to see the work piece during operation. Other important benefit is in its ability to emulsify any leakage of oil from the machine parts in the cutting fluid, a corrosion inhibitors, and bacteria control

9、.3. Mineral oil free synthetic is a mix of chemicals, water, bacteria control, corrosion inhibitors, and dyes. Does not contain any mineral oils, and provides good visibility.23 to the work piece. bare in mind that the lack of mineral oil in this type of cuttingfluid needs to take more attention to

10、machine parts lubrication since it should not leave an oily film on the machine parts, and might cause seals degradation due the lack of protection.5.1.2 Cutting Fluid SelectionMany factors influence the selection of cutting fluid; mainly work piece material, type of machining operation, machine too

11、l parts, paints, and seals. Table 5-1 prepared at the machine tool industry research association 2 provides suggestions on the type of fluid to be used.5.1.3 Coolant ManagementTo achieve a high level of cutting fluids performance and cost effectiveness, a coolant recycling system should be installed

12、 in the factory. This system will reduce the amount of new purchased coolant concentrate and coolant disposable, which will reduce manufacturing cost. It either done by the company itself or be rented out, depends on the budget and management policy of the company 1. Table 5-1 Guide to the selection

13、 of cutting fluids for general workshop applications.MachiningoperationWorkpiece materialFree machiningand low -carbon steelsMedium-Carbon steelsHigh Carbonand alloy steelsStainless andheat treatedresistantalloysGrindingClear type soluble oil, semi synthetic or chemical grinding fluidTurningGeneral

14、purpose, soluble oil, semisynthetic or synthetic fluidExtreme-pressure soluble oil,semi-synthetic or syntheticfluidMillingGeneralpurpose,soluble oil,semi syntheticor syntheticExtreme-pressure solubleoil, semi-synthetic orsynthetic fluidfluid（neat cutting oils may benecessary）DrillingExtremeoil, semi

15、Gear Shappingsemi-synthetic or synthetic fluidNeat-cutting oils preferableHobbingExtreme-pressure soluble oil, semi-synthetic orsynthetic fluid （neat cutting oils may be preferable）Neat-cuttingoilspreferableBratchingExtreme-pressure soluble oil, semi-synthetic or synthetic fluid （neatcutting oils ma

16、y be preferable）Tappingsynthetic fluid（neat cutting oils may be necessary）Note: some entreis deliberately extend over two or more columns, indicating a wide range of possible applications. Other entries are confined to a specific class of work material.Adopted from Edward and Wright 25.2 Wear Mechan

17、isms Under Wet High Speed MachiningIt is a common belief that coolant usage in metal cutting reduces cutting temperature and extends tools life. However, this research showed that this is not necessarily true to be generalized over cutting inserts materials. Similar research was carried out on diffe

18、rent cutting inserts materials and cutting conditions supporting our results. Gu et al 36 have recorded a difference in tool wear mechanisms between dry and wet cutting of C5 milling inserts. Tonshoff et al 44 also exhibited different wear mechanisms on AL2O3/TiC inserts in machining ASTM 5115, when

19、 using coolants emulsions compared to dry cutting. In addition, Avila and Abrao 20 experienced difference in wear mechanisms activated at the flank side, when using different coolants in testing AL2O3lTiC tools in machining AISI4340 steel. The wear mechanisms and the behavior of the cutting inserts

20、studied in this research under wet high speed-machining （WHSM） condition is not fully understood. Therefore, it was the attempt of this research to focus on the contributions in coating development and coating techniques of newly developed materials in order to upgrade their performance at tough mac

21、hining conditions. This valuable research provides insight into production timesavings and increase in profitability. Cost reductions are essential in the competitive global economy; thus protecting local markets and consisting in the search of new ones.5.3 Experimental Observations on Wear Mechanis

22、ms of Un-Coated Cemented Carbide Cutting Inserts in High Speed Wet MachiningIn this section, the observed wear mechanisms are presented of uncoated cemented carbide tool （KC313） in machining ASTM 4140 steel under wet condition. The overall performance of cemented carbide under using emulsion coolant

23、 has been improved in terms of extending tool life and reducing machining cost. Different types of wear mechanisms were activated at flank side of cutting inserts as a result of using coolant emulsion during machining processes. This was due to the effect of coolant in reducing the average temperatu

24、re of the cutting tool edge and shear zone during machining. As a result abrasive wear was reduced leading longer tool life. The materials of cutting tools behave differently to coolant because of their varied resistance to thermal shock. The following observations recorded the behavior of cemented

25、carbide during high speed machining under wet cutting.Figure 5-1 shows the flank side of cutting inserts used at a cutting speed of 180m/min. The SEM images were recorded after 7 minutes of machining. It shows micro-abrasion wear, which identified by the narrow grooves along the flank side in the di

26、rection of metal flow, supported with similar observations documented by Barnes and Pashby 41 in testing through-coolant-drilling inserts of aluminum/SiC metal matrix composite. Since the cutting edge is the weakest part of the cutting insert geometry, edge fracture started first due to the early non-smooth engagement between the tool and the work piece material. Also, this is due to stress concentrations that might lead to a cohesive failure on the transient filleted flank cutting wedge region 51, 52. The same image of m