外文翻譯--切削刃的幾何形狀工件的硬度的影響進給速度和切削速度對表面粗糙度和力量完成硬化aisi h13鋼的車削 英文版

1、<p>　　EFFECTS OF CUTTING EDGE GEOMETRY,WORKPIECE HARDNESS, FEED RATE AND CUTTING SPEED ON SURFACE ROUGHNESS AND FORCES IN FINISH TURNING OF HARDENED AISI H13 STEEL</p><p>　　Tugrul Özel, Tsu-Kong Hs

2、u, Erol Zeren </p><p>　　Department of Industrial and Systems Engineering Rutgers, The State University of New Jersey, New Jersey 08854 USA</p><p><b>　　Abstract</b></p><p&g

3、t;　　In this study, effects of cutting edge geometry, workpiece hardness, feed rate and cutting speed on surface roughness and resultant forces in the finish hard turning of AISI H13 steel were experimentally investigated

4、. Cubic boron nitrite inserts with two distinct edge preparations and through-hardened AISI H-13 steel bars were used. Four factor (hardness, edge geometry, feed rate and cutting speed)- two level fractional experiments

5、were conducted and statistical analysis of variance was performe</p><h2>　　1. INTRODUCTION </h2><p>　　Hard turning, machining ferrous metal parts that are hardened usually between 45-70 HRC, can

6、 be performed dry using polycrystalline cubic boron nitride (PCBN, commonly CBN) cutting tools as extensively reported in literature [1-8]. Research results in the literature concerning mechanism of serrated chip formati

7、on in order to relate process characteristics and stability of cutting to the chip shapes during hard turning [9-19]. Other research concerning with composition, temperatures and wear char</p><p>　　Cutting t

8、ool geometry and material properties</p><p>　　Hard turning with CBN cutting tools demands prudent design of tool geometry. CBN cutting tools have lower toughness than other common tool materials, thus chippi

9、ng ismore likely [2]. Therefore, a nose radius and proper edge preparation are essential to increase the strength of cutting edge and attain favorable surface characteristics on finished metal components [23]. CBN cuttin

10、g tools designed for hard turning feature negative rake geometry and edge preparation (a chamfer or a hone, or even bot</p><p>　　Fig. 1. A flow chart illustrating relationships of factors in hard turning.<

11、;/p><p>　　Theile et al. [24, 25], presented research results of an experimental investigation of effects of cutting edge geometry and workpiece hardness on residual stresses in finish hard turning of AISI 52100

12、 steel. They indicated that both factors are significant for the surface integrity of finish hard turned components. Specifically, they showed that large hone radius tools produce more compressive stresses, but also leav

13、e “white-layers”. Özel [26] investigated the influence of edge geometry in CBN t</p><p>　　Fig. 2. Type of edge preparations for CBN cutting tools.</p><h4>　　1.2 Workpiece hardness </h2&g

14、t;<p>　　Due to the changes in properties of hardened workpiece material, basic shearing process and formation of chips differ in hard turning [5]. Prior research showed that workpiece hardness has a profound effec

15、t on the performance of the CBN tools [1,2,8] and also integrity of finish machined surfaces [23,25]. Matsumoto et al. [23] and Thiele et al. [25] studied the effect of workpiece hardness on residual stresses. In a recen

16、t study, Guo and Liu [27] investigated material properties of hardened AISI</p><h4>　　1.3 Cutting speed, feed rate and depth of cut </h2><p>　　Performance of CBN cutting tools is highly dependen

17、t on the cutting conditions i.e. cutting speed, feed, feed-rate, and depth of cut [7]. Especially cutting speed and depth of cut significantly influence tool life [22]. Increased cutting speed and depth of cut result in

18、increased temperatures at the cutting zone. Since CBN is a ceramic material, at elevated temperatures chemical wear becomes a leading wear mechanism and often accelerates weakening of cutting edge, resulting in premature

19、 tool fai</p><h4>　　1.4 Surface integrity, residual stresses and tool wear </h2><p>　　In general, residual stresses become more compressive as workpiece hardness increases. The hardness and frac

20、ture toughness of CBN tools decrease with reduced CBN content [8]. Owing to ceramic binder phase, CBN-L tools have a lower thermal conductivity, which causes increasing temperatures of cutting edge during hard turning. C

21、hou and Barash [9] reported that CBN-L tools are more suitable for finish turning of hardened steel. At low cutting speeds, tool life of CBN-L is superior to CBN-H, whereas</p><h4>　　1.5 Accuracy and rigidit

22、y of the machine tool </h2><p>　　Another parameter that is often ignored is tool vibration. In order to reduce tool vibration it is necessary provide sufficiently rigid tool and workpiece fixtures. Assuring

23、that there is minimal tool vibration is an easy way to improve surface roughness. It is also necessary that the tooling system be extremely rigid to withstand the immense cutting forces. It is well known that the radial

24、force is the largest among force components during hard turning. Many researchers indicated that extremely</p><p>　　To improve the overall efficiency of finish hard turning, it is necessary to have a complet

25、e process understanding. To this end, a great deal of research has been performed in order to quantify the effect of various hard turning process parameters to surface quality. In order to gain a greater understanding of

26、 the hard turning process it is necessary to understand the impact of each of these variables, but also the interactions between them. It is impossible to find all of the variables that imp</p><h2>　　2. EXPE

27、RIMENTAL PROCEDURE </h2><h4>　　2.1 Workpiece material </h2><p>　　The workpiece material used in this study was AISI H13 hot work tool steel, which is used for high demand tooling. The cylindrica

28、l bar AISI H13 specimen that are utilized in this experiments had a diameter of 1.25 inches and length of 2 feet. The bar specimens were heat treated (through-hardened) at in-house heat treatment facility in order to obt

29、ain the desired hardness values of 50 and 55 HRC. However, the subsequent hardness tests by using Future Tech Rockwell type hardness tester revealed th</p><h4>　　2.2 Tooling and edge geometry </h2>&l

30、t;p>　　CBN inserts with two distinct representative types of edge preparations were investigated in this study. These edge preparations include: a) “chamfered” (T-land) edges and b) “honed” edges as illustrated in Fig.

31、2. Solid top CBN inserts (TNM-433 and GE Superabrasives BZN 8100 grade) inserts were used with a Kennametal DTGNR-124B right hand tool holder with 00 lead and –50 rake angles. Honed and chamfered insert edge geometry wer

32、e measured in coordinated measurement machine with three replications</p><h4>　　2.3 Experimental design </h2><p>　　A four factor – two level factorial design was used to determine the effects of

33、 the cutting edge geometry, workpiece hardness, feed rate and cutting speed on surface roughness and resultant forces in the finish hard turning of AISI H 13 steel. The factors and factor levels are summarized in Table 1

34、. These factor levels results in a total of 16 unique factor level combinations. Sixteen replications of each factor level combinations were conducted resulting in a total of 256 tests. Each replicatio</p><p&g

35、t;　　Longitudinal turning was conducted on a rigid, high-precision CNC lathe (Romi Centur 35E) at a constant depth of cut at 0.254 mm. The bar workpieces were held in the machine with a collet to minimize run-out and maxi

36、mize rigidity. The length of cut for each test was 25.4 mm in the axial direction. Due to availability constraints, each insert were used for one factor level combination, which consisted of 16 replications. (A total of

37、three honed and three chamfer inserts were available). In this m</p><h4>　　2.4 Cutting force measurements </h2><p>　　The cutting forces were measured with a three-component force dynamometer (Ki

38、stler Type 9121) mount on the turret disk of the CNC lathe via a custom designed turret adapter (Kistler type 9121) for the toolholder creating a very rigid tooling fixture. The charge signal generated at the dynamometer

39、 was amplified using charge amplifiers (Kistler Type 5814B1). The amplified signal is acquired and sampled by using data acquisition PCMCIA card and Kistler DyanoWare software on a laptop computer at a s</p><p

40、>　　Fig. 3. Measured cutting-force components.</p><p>　　3. RESULTS AND DISCUSSION </p><p>　　An analysis of variance (ANOVA) was conducted to identify statistically significant trends in the me

41、asured surface roughness and cutting force data. Separate ANOVA analyses were conducted for Ra surface roughness values and for each component of the cutting force i.e. axial (feed), radial (thrust), and tangential (cutt

42、ing) forces. Additionally, plots of significant factors corresponding to each ANOVA analysis were constructed. These plots provide a more in-depth analysis of the significant facto</p><p>　　3.1 ANOVA results

43、 </p><p>　　ANOVA tables for Ra surface roughness parameters are given in Table 2. In addition to degree of freedom (DF), mean square (MS) and F values (F) the table shows the P-values (P²) associate wit

44、h each factor level and interaction. A low P-value indicates an indication of statistical significange for the source on the response. Table 2 show that the main effects of edge geometry, cutting speed and feed rate exce

45、pt hardness, interactions between edge geometry and hardness, feed rate, and cutting spee</p><p>　　The radial force is usually the largest, tangential force is the middle and the axial (feed) force is the sm

46、allest in finish hard turning. In general, cutting force components are influences by cutting speed, edge geometry and feed rate. Tables 3-5 are ANOVA tables corresponding to the radial, axial (feed force) and tangential

47、 components of the cutting force, respectively. These tables show that the main effects of workpiece hardness, the edge geometry, cutting speed and feed rate (except for ax</p><p>　　Table 3 shows that the ma

48、in effects of the edge geometry, cutting speed, hardness and the interactions between edge geometry and hardness, cutting speed, feed rate are significant with respect to the forces in the axial (feed) direction. Axial (

49、feed) force is not much influence by the change in feed rate. </p><p>　　Table 4 shows that the main effects of the edge geometry, cutting speed, hardness and only the interactions between edge geometry and c

50、utting speed, feed rate are significant with respect to the forces in the radial direction.</p><p>　　Table 5 shows that the main effects of the edge geometry, cutting speed, hardness, feed and only the inter

51、actions between edge geometry and hardness, cutting speed, feed rate are significant with respect to the forces in the tangential direction.</p><p>　　3.2 Effect of feed rate and edge preparation on surface r

52、oughness </p><p>　　Graphs of Ra surface roughness parameters are shown in Figures 4 and 5. These figures have been constructed to illustrate the main effects of edge geometry and feed rate parameters on the

53、surface roughness. Based on the previous analysis, the main effect of the interaction between edge geometry and feed rate are found to be statistically significant on surface roughness Ra. Fig. 4 shows the effect of edge

54、 geometry and feed rate on the Ra surface roughness parameter for 54.7 HRC, cutting speed 20</p><p>　　Fig. 4. Effect of cutting edge geometry and feed rate on surface roughness (high levels).</p><

55、p>　　Fig. 5. Effect of cutting edge geometry and feed on surface roughness (low levels).</p><p>　　These two figures show that all edge preparations are confounded at the lowest feed rate (0.05mm/rev). Howe

56、ver, the large edge radius resulted in better surface roughness when higher hardness and cutting speed selected, whereas it is the opposite when lower hardness and cutting speed selected. Finally, it should be noted that

57、 the main effect due to feed is readily apparent for each edge preparation. Specifically, the surface roughness increases as the feed rate increases as the surface roughness</p><h4>　　3. 3 Effect of surface

58、hardness and edge preparation on surface roughness </h2><p>　　Fig. 6 is constructed to illustrate the main effects of edge geometry and surface hardness parameters on the surface roughness with cutting speed

59、 200 m/min, feed rate 0.2 mm/rev and cutting length 406.4 mm. Based on the previous analysis, the main effect of the interaction between edge geometry and workpiece surface hardness are statistically significant to surfa

60、ce roughness Ra parameters. The figure shows that small edge radius and lower workpiece surface hardness resulted in better surface rou</p><p>　　Fig. 6. Effect of cutting edge geometry and hardness on surfac

61、e roughness.</p><h4>　　3.4 Effect of surface hardness and edge preparation on tangential, radial and axial (feed) forces </h2><p>　　Graphs of the force components as functions of edge geometry a

62、nd workpiece surface hardness are shown in Figs. 7-9. These figures show that chamfered edge geometry and higher workpiece surface hardness result in higher tangential and radial forces but not in axial (feed) force. Add

63、itionally, small honed radius edge geometry results in higher forces in the axial (feed) directions. </p><p>　　Fig. 7: Effect of cutting edge geometry and surface hardness on tangential force.</p><

64、;p>　　Fig. 8: Effect of cutting edge geometry and surface hardness on radial force.</p><p>　　Fig. 9: Effect of cutting edge geometry and surface hardness on axial force.</p><h4>　　3.5 Effect o

65、f cutting speed and cutting edge geometry on tangential force </h2><p>　　Fig. 10 is obtained to illustrate the main effects of edge geometry and cutting speed parameters on tangential force. Based on the pre

66、vious analysis, the main effect of the edge geometry and cutting speed are statistically significant to tangential force. Fig. 10 shows that higher cutting speed and smaller edge radius resulted in lower tangential force

67、. </p><h4>　　3.6 Effect of cutting speed and feed rate on tangential force </h2><p>　　Fig. 11 is obtained to illustrate the main effects of cutting speed and feed rate parameters on tangential f

68、orce. Based on the previous analysis, the interaction of cutting speed and feed rate are statistically significant to tangential force. Fig. 11 shows that lower cutting speed and lower feed rate resulted in lower tangent

69、ial force.</p><p>　　Fig. 10 Effect of cutting speed and cutting edge geometry on tangential force.</p><p>　　Fig. 11. Effect of cutting speed and feed rate on tangential force.</p><h2&

70、gt;　　4. CONCLUSIONS </h2><p>　　In this study, a detailed experimental investigation is presented for the effects of cutting edge preparation geometry, workpiece surface hardness and cutting conditions on the

71、 surface roughness and cutting forces in the finish hard turning of AISI H13 steel. The results have indicated that the effect of cutting edge geometry on the surface roughness is remarkably significant. The cutting forc

72、es are influenced by not only cutting conditions but also the cutting edge geometry and workpiece surfac</p><p>　　This study shows that the effects of workpiece hardness, cutting edge geometry, feed rate and

73、 cutting speed on surface roughness are statistically significant. The effects of two-factor interactions of the edge geometry and the workpiece hardness, the edge geometry and the feed rate, and the cutting speed and fe

74、ed rate are also appeared to be important. Especially, small edge radius and lower workpiece surface hardness resulted in better surface roughness. Cutting edge geometry, workpiece hardne</p><p>　　5.ACKNOWLE

75、DGMENTS </p><p>　　Authors would like to acknowledge Mr. Joseph Lippencott and Talat Khaireddin for their assistance in conducting experiments.</p><h2>　　REFERENCES </h2><p>　　1. N.

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86、n”, Journal of Materials Processing and Technology, Vol. 71, 1997, pp. 247-257.</p><p>　　High Productivity —A Question of Shearer Loader Cutting Sequences</p><p>　　K. Nienhaus, A. K. Bayer &

87、 H. Haut, Aachen University of Technology, GER</p><p><b>　　Abstract</b></p><p>　　Recently, the focus in underground longwall coal mining has been on increasing the installed motor po

88、wer of shearer loaders and armoured face conveyors (AFC), more sophisticated support control systems and longer face length, in order to reduce costs and achieve higher productivity. These efforts have resulted in higher

89、 output and previously unseen face advance rates. The trend towards “bigger and better” equipment and layout schemes, however, is rapidly nearing the limitations of technical and </p><p>　　1 Introductions<

90、;/p><p>　　Traditionally, in underground longwall mining operations, shearer loaders produce coal using either one of the following cutting sequences: uni-directional or bi-directional cycles. Besides these pre-

91、dominant methods, alternative mining cycles have also been developed and successfully applied in underground hard coal mines all over the world. The half-web cutting cycle as e.g. utilized in RAG Coal International’s Twe

92、ntymile Mine in Colorado, USA, and the “Opti-Cycle” of Matla’s South African sho</p><p>　　Whereas the mentioned mines are applying the alternative cutting methods according to their spe-cific conditions, –e.

93、g. seam height or equipment used, –this paper looks systematically at the differ-ent methods from a generalised point of view. A detailed description of the mining cycle for each cutting technique, including the illustra

94、tion of productive and non-productive cycle times, will be followed by a brief presentation of the performed production capacity calculation and a summary of the t</p><p>　　2 State-of-the-art of shearer load

95、er cutting sequences</p><p>　　The question “Why are different cutting sequences applied in longwall mining?” has to be an-swered, before discussing the significant characteristics in terms of operational pro

96、cedures. The major constraints and reasons for or against a special cutting method are the seam height and hard-ness of the coal, the geotechnical parameters of the coal seam and the geological setting of the mine influe

97、ncing the caving properties as well as the subsidence and especially the length of the longwall face. F</p><p>　　A categorization of shearer loader cutting sequences is realised by four major parameters . Fi

98、rstly, one can separate between mining methods, which mine coal in two directions – meaning from the head to the tailgate and on the return run as well – or in one direction only. Secondly, the way the mining sequence de