外文翻譯--在高速磨削中冷卻液速度的分析與實驗研究（英文版）

1、International Journal of Machine Tools received in revised form 16 February 2004; accepted 26 February 2004AbstractUse of water-base coolant is a pre-requisite in an high speed grinding process to avoid thermal damage a

2、nd to achieve better surface integrity as well as higher grinding ratio. However, the presence of hazardous chemical additives in the coolant causes environmental problems. As a result, stringent government legislation i

3、s being practiced for the coolant use and disposal, which consumes 7–17% of the total machining cost. This paper reports the coolant flux minimization through controlled jet impinge- ment so as to prolong the coolant rep

4、lenishment cycle. Control of coolant flux was achieved through development of a ‘‘metered quantity coolant’’ (MQC) nozzle which supplies the required amount of coolant to the grinding zone. Also, this investigation has s

5、hown that coolant velocity has a significant influence on the high speed grinding performance. When the coolant velocity is inadequate, coolant could not penetrate into the grinding zone. The increase in coolant velocity

6、 was realized with reduction in nozzle opening area and does not use a large quantity of coolant. This is of significance to reduce environmental pollution and machining costs through extended coolant replenishment perio

7、d. # 2004 Elsevier Ltd. All rights reserved.Keywords: High speed grinding; Coolant flux; Coolant1. IntroductionThe high speed grinding process consumes five to six times higher grinding energy and therefore use of copi-

8、ous coolant to avoid thermal damage, to achieve better surface integrity and higher tool life through friction reduction as well as cooling is commonly seen [1]. However, the presence of chemical substances like sulfur,

9、phosphorous, chlorine or any other extreme pressure additives in the coolant introduces health hazard to the operator [2]. It is well documented that 7–17% of machining cost of a work-piece is due to coolant-lubricant de

10、ployment [3]. The disposal of used chemical coolants involves incineration and partially contributes to global warming [4]. Also, use of flood coolants does not inhibit the air boundary layer and a protocol was made for

11、further investigation of coolantflow mechanism [5]. In view of this, ecological machin- ing has gained its significance through introduction of: (i) dry machining (ii) effective and prolonged usage of coolant through opt

12、imization and nozzle design. This paper reports the coolant flux minimization and the related grinding characteristics through controlled jet impingement.2. AnalysisThe interaction between wheel and work-piece generates

13、thermal energy due to friction and plastic deformation. The generated heat is transferred to work-piece, grinding swarf, coolant and wheel (see Fig. 1). Previously developed models quantify the actual grinding temperatur

14、e rise and the cooling effect with emphasis to the physical properties of coolant [6,7]. In this analysis, the role of coolant exit velocity in disseminating the heat generated in high speed grinding process was analyzed

15、. Grinding wheel was considered to be a solid disk with a thin abrasive layer where irregular shaped? Corresponding author. Tel.: +65-9627-5884; fax: +65-6793-5774. E-mail addresses: ramesh@pmail.ntu.edu.sg (K. Ramesh),

16、rkup- puswamy@simtech.a-star.edu.sg (K. Ramesh).0890-6955/$ - see front matter # 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijmachtools.2004.02.017This equation suggests that pressure drop and the ratio of noz

17、zle exit to inlet is of significance for admin- istrating the coolant velocity parameter.3. Coolant supply methodIn contrast to the normal coolant setup that supplies copious amount of coolant to the grinding zone, a noz

18、zle that supplies metered amount of coolant was developed. As shown in Fig. 3, this system consists of a flow meter, a pressure gage, a manifold and changeable nozzles. Three different nozzles with cross-sectional area 1

19、5.14–50.26 mm2 were included in this design. The nozzle characteristics in terms of flow, pressure and velocity are given in Table 1. Shown in Fig. 4 is the photo of the developed nozzle arrangement with flow meter and p

20、ressure gage, integrated to the wheel head.4. Experimental conditionsFor each nozzle, a series of grinding tests were per- formed on SS304 at a pre-fixed grinding condition. Coolant flow rate and pressure were adjusted t

21、o vary the coolant velocity (vc) for investigating the grindingperformance. During the process both normal (Fn) andtangential (Ft) grinding forces were measured using a9265B Kistler dynamometer for computing the forcerat

22、io (Ft/Fn), power-flux (Q) and grinding energy (E).The onset of burn in grinding was quantitativelyexpressed in terms of power-flux using Eq. (7) as [10],Power-flux ðQÞ ¼ FtVb ffiffiffiffiffiffiffiffiffiff

23、iffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi DD½1 þ v=V? p ð7Þwhere Ft is the tangential force (N), V is the wheelspeed (m/s), v is the table feed rate (m/s), b is thewheel width (mm), D is t

24、he wheel diameter (mm) andD is the depth of cut (mm). Eq. (7) suggests thatpower-flux is likely to increase upon increase of wheelspeed, tangential grinding force but reduces withincrease of contact area. The specific en

25、ergy for cutting, which is that portionof the specific grinding energy remaining after subtract-ing the contribution due to sliding was computed fromthe relationship shown in Eq. (8).E ¼ ftVvD ð8Þwhere V i

26、s the wheel speed, v is the Table feed, D is thedepth of cut and ft is the specific grinding force in tan-gential direction of grinding wheel. Ground samples were examined using a scanningelectron microscope at a magnifi

27、cation ? 1000 and ?50to characterize the surface integrity. Also, a 3D surfacemicrograph was taken using optical interference pro-filer (Wyko NT 3300) for examination of the coolantvelocity related surface changes. Table

28、 2 lists the grind-ing conditions used for the experiments.Fig. 3. Schematic layout of grinding with coolant penetration.Table 1 Characteristics of nozzleNozzle cross-sectional area (mm2) Coolant pressure (bar) Coolant f