人人文库网 > 毕业设计 > 文献翻译 > 机械类外文翻译【FY192】凸轮形状设计的混合方法和一般的盘形凸轮轮廓加工的机制【PDF+WORD】【中文3000字】
机械类外文翻译【FY192】凸轮形状设计的混合方法和一般的盘形凸轮轮廓加工的机制【PDF+WORD】【中文3000字】
收藏
资源目录
压缩包内文档预览：
编号：446499
类型：共享资源
大小：932.85KB
格式：ZIP
上传时间：2015-07-03
上传人：棒***
认证信息
个人认证
康**（实名认证）
湖北
IP属地：湖北
12
积分
- 关 键 词：
-
机械类
外文
翻译
fy192
凸轮
形状
设计
混合
方法
法子
以及
一般
轮廓
加工
机制
pdf
word
中文
- 资源描述：
-
机械类外文翻译【FY192】凸轮形状设计的混合方法和一般的盘形凸轮轮廓加工的机制【PDF+WORD】【中文3000字】,机械类,外文,翻译,fy192,凸轮,形状,设计,混合,方法,法子,以及,一般,轮廓,加工,机制,pdf,word,中文
- 内容简介：
-
INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 11, No. 3, pp. 419-427 JUNE 2010 / 419DOI: 10.1007/s12541-010-0048-6 1. Introduction Plate cam mechanism is a widely used machine component with the continuous contact motion of cam and follower, and can easily produce any functional motion of follower due to the rotation of cam. Cam mechanism has the diverse types by the combination of different shape of cam and motion of follower; plate or cylindrical cam, roller or flat-faced follower, and reciprocating or oscillating motion. In spite of the advantages of a few number of links, simple structure, positive motion, and compact size, cam mechanisms require the accurate shape design and precise machining procedures for satisfying the mechanical requirements. Under the low leveled design and manufacturing, cam mechanisms give the heavy effects on vibration, noise, separation, and overloading to an overall system. To avoid these effects, cam mechanism must be well designed accurately and machined precisely. Actually, a hybrid CAD/CAM approach may be the best solution that the shape data from the design process are directly combined to the machining data for the manufacturing process. Line interpolation and circular interpolation are commonly used in construction of the machining data from the profile data of cam. Line interpolation has the low accuracy and circular interpolation can not keep the accuracy because of the disconnective radii of curvatures or the discontinuous slopes at the connected point by two circular arcs as presented in Shin et al.1-3Recently, parameteric interpolation using B-spline and NURBS curve are suggested in Jung et al.5and Yang et al.6Also biarc interpolation is widely used and deeply dependent on the direction angle toward centers of biarc curves. Bolton7described a biarc curve based on the tangential angles at two points, Parkinson and Moreton8made a biarc curve based on a quadratic equation at three points, Meek and Walton9used spline types for constuction of biarc curve. Schonherr10introduced an approach to minimize the radii of biarc curves. Commonly these interpolation methods make the machining points increasing and then the excessive data for machining a curved shape make the machining errors increased. Thus, the precise machining process requires minimization of the machining points to keep the accuracy under a given machining tolerance. This paper introduces 3 steps of a hybrid CAD/CAM A Hybrid Approach for Cam Shape Design and Profile Machining of General Plate Cam Mechanisms Joong-Ho Shin1, Soon-Man Kwon1and Hyoungchul Nam1,#1 Department of Mechanical Design & Manufacturing, Changwon National University, #9, Sarim-dong, Changwon, Kyungnam, South Korea, 641-773# Corresponding Author / E-mail: nhchulchangwon.ac.kr, TEL: +82-55-267-1106, FAX: +82-55-267-1106KEYWORDS: Plate cam mechanism, Cam, Follower, Shape design, Profile machining, Contact point, NC data, Instant velocity center, Biarc curve fittingPlate cam mechanism can easily produce the positive and functional motions in contact of cam and follower. Generally cam mechanism is used in many fields of mechanical control, automation, and industrial machinery. To obtain the accurate motion of follower, the profile of cam must be designed and machined precisely. This paper proposes an instant velocity center method for the profile design and a biarc fitting method for the profile machining to 4 different types of plate cam mechanisms with reciprocating or oscillating motion and roller or flat-faced followers. The key of this paper is the introduction of a hybrid system combined the design procedures and the manufacturing procedures. The main idea is that the minimum machining data are built by the accurate biarc curves fitted directly from the design parameters. The radial direction angles toward biarc centers for the accurate biarc curve fitting can be defined directly by the contact angle of cam and follower given in the design procedures. An application of the proposed approach is verified the accurate profiles of a designed cam and a machining cam using the minimum NC data within a given machining tolerance. Manuscript received: July 16, 2009 / Accepted: February 18, 2010 KSPE and Springer 2010 nts420 / JUNE 2010 INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 11, No. 3approach11for 4 different types of plate cam mechanisms. Firstly, the shape of cam is determined by the kinematic constraints at instant velocity centers and the contact angle at the contact point between cam and follower. The second step is to transform the contact angles into the center direction angles and then to calculate the radii of biarc curve. Finally, the machining data are minimized through expanding or contracting the biarc section whether the cam profile points are located inside or outside the range of a given machining tolerance. 2. Clarification of Accuracy on Biarc Fitting1-3Only the profile data of cam shape are defined in common design process of a plate cam. Then, the machining data must be developed by any curve fitting for NC (Numerical control) process. The circular fitting, which is most widely used in machining, has unreliability as shown in Fig. 1. A circle developed by three points 1(,P2,P3)P has a radius 1R and the other by points 2(,P3,P4)P has 2.R In the views of circular fitting two circles pass the profile points 1(,P2,P3,P4),P but the discontinuous slopes are made at these points and also the disconnective radii at points in mid-span. These defects make the fitted curve in low accuracy and then higher vibration in high speed operation of cam mechanism. P4P3P2P1O2O1R1R2S1S2SSlope 1Slope 2Fig. 1 Defects on circular fitting 3231R4R2P4P3O4O3S3S2R3S1P2O2O1P1R121112212Fig. 2 Continuous fitting by biarc Fig. 2 shows a continuous curve fitted by biarcs, which passes the profile points 1(,P2,P3,P4).P The biarc curve has 4 radii in this case. Radius 1R passes 1P to 1,S 2R for 1S to 2.S 3R for 2S to 3,S and 4R for 3S to4.P The slopes of the biarc curve are continuous and unique at every point. Also mid-points 1(,S2,S3)S are continuous without jump in radii. Thus, the biarc curve can keep the higher level of accuracy. As shown in Fig. 2, biarc fitting is highly dependent on radial direction angles (). The common design process of cam mechanism defines only the profile data and then machining process must use the angles from the circular fitting. This process gives the lower accuracy because of the incorrect angles. But the proposed approach in this paper can define the correct angles, which are given directly by design process of cam profile, and then keep the higher accuracy for the machining data. 3. Shape Design of Plate Cam 3.1 Displacement characteristics of cam mechanism For a plate cam mechanism with reciprocating roller follower shown in Fig. 3, the kinematic properties of follower motion can be defined as linear displacement ,Y first derivative ,Y and second derivative Y to the rotational angle c of cam. And the properties are given as angular displacement in case of oscillating follower. The instant velocity center method given in this paper uses the displacements and the 1st derivatives for determining the cam shape. CamFollowerContact point coordinateCam shape coordinatecCRSyxFig. 3 Plate cam mechanism with reciprocating roller follower 3.2 Shape design based on instant velocity centers4As shown in Fig. 4, Point Q is defined by a line through contact point C from roller center and a horizontal line and then it becomes instant velocity center. The velocity at point Q is proportional to a rotating speed of cam as in Eq.(1) and the velocity of roller at point R is defined in Eq.(2) as the linear velocity of follower. cQQdVLdt= (1) cRcdY dY dVdt d dt= (2) ntsINTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 11, No. 3 JUNE 2010 / 421By the kinematic characteristics of cam mechanism, the velocity at the instant velocity center ,QV is same as the velocity of follower .RV Thus, the velocity condition gives the location of the instant velocity center in Eq.(3). QcdYL Yd= (3) QR(Rx, Ry)LQVQVRcRrYxyC(Cx, Cy)Fig. 4 Contact position of cam and follower The contact angle shown in Fig. 4 is defined in Eq.(4) by a angle between a sliding velocity line and a normal line at a contact point of follower roller. The coordinates of the contact point are given in Eq.(5) where the coordinates of a roller center (,xR )yR can be calculated from the displacement ()Y and the geometric conditions (prime circle and eccentricity) of a given cam mechanism, and where rR is the radius of roller. Finally, the contact point (xC and )yC is given in Eq.(5) 1tanQxyL RR= (4) sinsinxxryyrCRRCRR=+=(5) QLQVQVfcYxC(Cx, Cy)F(Fx, Fy)Fig. 5 Plate cam with reciprocating flat-faced follower Fig. 5 shows a cam mechanism with reciprocating flat-faced follower. Instant velocity center Q is located on the horizontal line and defined in Eq.(6) based on the velocity conditions at instant velocity centers. Then, the contact point is defined in Eq.(7) QcdYLd= (6) x Qy yCLCF=(7) For a mechanism with oscillating roller follower as in Fig. 6, the distance of instant velocity center from cam center becomes in Eq.(8). The contact angle between cam and roller is expressed in Eq.(9) and then the contact point is defined in Eq.(10). Here, Zxyis the distance to a pivot from cam center. 1fxycQfcdZdLdd=+(8) 1tanQxyL RR= (9) sinsinxxryyrCRRCRR=+=(10) fQLQVQVRRZLZxycR(Rx, Ry)xyC(Cx, Cy)RrFig. 6 Plate cam with oscillating roller follower In a case of cam mechanism with oscillating flat-faced follower as shown in Fig. 7, the location of instant velocity center is formulated as in Eq.(11) and the contact point is given in Eq.(12) 1fxycQfcdZdLdd=+(11) ( )()2coscos sinx xy xy Q fy xy Q f fCZ Z LCZL= =(12) nts422 / JUNE 2010 INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 11, No. 3fQLQVQVfVfZLZxycxyC(Cx, Cy)F(Fx, Fy)Fig. 7 Plate cam with oscillating flat-faced follower Finally, the profile of cam shape can be determined by transforming the contact point with the reverse angle of cam rotation as in Eq.(13), where xS and yS are the coordinates of cam profile. cos sinsin cosxx cy cy xcy cSC CSC C=+= +(13) 3.3 Internal normal angle at contact point The normal line at each contact point is shown in Figs. 4-7 for 4 different cases of the plate cam mechanisms. In this paper an internal normal angle () is defined as an angle between lines connected to cam center and to instant velocity center from contact point as shown in Fig. 8. Because tool centers for machining and biarc centers for curve fitting are located on the normal direction line through contact point, the internal normal angle must be transferred to the machining data process in order to guarantee the precise shape of cam. The position angle ()c of contact point shown in Fig. 8 is easily defined as in Eq.(14). Also the normal line angle ()f at contact point for cam mechanism with roller follower in Fig. 8(a) and Fig. 8(c) is same as in Eq.(15). The normal line angles are defined in Eq.(16) for reciprocating flat-faced follower (Fig. 8(b) and in Eq.(17) for oscillating flat-faced follower (Fig. 8(d), respectively. 1tanycxCC=(14) 1tanyyfxxR CR C=(15) 90fface slope angle = (16) 1tan 90yyfxxCZCZ=(17) Finally, the internal normal angle at contact point on cam profile can be expressed in Eq.(18) for plate cam mechanisms as shown in Fig. 8. f c = (18) CamFollowerfcRollercoordinateContact pointcoordinateCRyxairplane(a) Reciprocating roller follower CamFollowercfface slope angleContact pointcoordinateCyxQ(b) Reciprocating flat-faced follower CamFollowerfcRollercoordinateContact pointcoordinateCRyxQ(c) Oscillating roller follower CamFollowerfcContact pointcoordinatePivotcoordinateCZx, ZyyxQ(d) Oscillating flat-faced follower Fig. 8 Internal normal angles of plate cam mechanism ntsINTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 11, No. 3 JUNE 2010 / 4234. Biarc Interpolation74.1 Characteristics of biarc curve Biarc interpolation is to connect the two circular arcs inside of a span connected by 2 points, where the biarc must have one tangential component at each point. Thus, all of points on a biarc interpolated curve have the unique slope and also have the unique direction angle toward the biarc center (It is called by radial direction angle in this paper). The radial direction angles 1( and 2) in Fig. 9 can be defined angles between a radial line to a center and a connected line on a span. Biarc interpolation is deeply dependent on the radial direction angle in a view of accuracy. Biarc curve can be categorized into 4 different types by combination of radial direction angles in a span as shown in Fig. 9, i.e. Fig. 9(a) is case 1 1(0 Fig. 9(b) is case 2 1(0 and 20) and 20). Here, centers of a biarc curve in case 1 and case 2 are located in the same plane and biarc curve becomes continuous smoothly. Centers in case 3 and case 4 are positioned in the cross plane and a inflection point must be existed on biarc curve as shown in Fig. 9. 4.2 Definition of equation for biarc curve Fig. 10 shows biarc curves with same planar centers, where a radius 1R consists of an arc from point 1 to *S at a center 1O and a radius 2R makes an arc from *S to point 2 at a center 2.O The point *S is located on the common radial line. By connected two circular arcs continuously, all points on biarc curve have the continuous tangential components on the span with point 1 and 2. Biarc curve with the same planar centers in Fig. 10 have a convex or concave curve. By rearrangement of the radial direction angles 1( and 2), radii of arcs 1(R and 2)R and length of span (),L the equation for biarc curve with the same planar centers can be defined as in Eq.(19). ( )()12 1 2 1 2211222coscossinsin12cos cos 0RRLR R L +=(19) 1 2O1O2S*R1R2211 2O1O2R1R2S*21(a) Case 1 (b) Case 2 Fig. 10 Biarc with same planar centers 12O1O2R1R2S*2112O1O2R1R2S*21(a) Case 3 (b) Case 4 Fig. 11 Biarc with cross planar centers Fig. 11 shows biarc curves with cross planar centers, where a center 1O makes a circular arc with radius 1R in one plane and the other center 2O builds a circular arc with radius 2R in the opposite plane. Thus, a inflection point *S must be satisfied the conditions 12t1 t2n1 n21 2(a) Case 1 12t1t2n1 n21 2(b) Case 2 12t1t2n1n212(c) Case 3 12t1t2n1n212(d) Case 4 Fig. 9 Cases of biarc curves nts424 / JUNE 2010 INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 11, No. 3of 3 points 1(,O2O and *)S located on the same line and the continuity of the tangential components of 2 circular arcs at *.S The equation for biarc curve with cross planar centers is defined in Eq.(20). ( )()12 1 2 1 2211222coscossinsin12cos cos 0RRLR R L +=(20) 5. Profile Machining Based on Biarc Curve 5.1 Radial direction angle for biarc curve On the profile of plate cam contoured by the contact points, any two consecutive points build a biarc span and can be connected by a biarc curve as shown in Fig. 12. Effectiveness of biarc interpolation depends on the accuracy of radial direction angle () at each point, because the centers of biarc curve are located on the lines defined by the radial direction angle at span points. 1XYP2P1n1211n222Fig. 12 Position angles, slope angle and length Arbitrary span on cam profile can be positioned at two points (1 and 2) by rotation of cam as shown in Fig. 12. Here, is the slope angle of a connected line between point 1 and point 2 and is the internal normal angle at each point defined in section 2.3. Position angles at span points 1(p and 2)p can be easily defined by the coordinates of the points from cam center. Thus, the radial direction angles at span points on biarc span are arranged as in Eq.(21). 11 122 2180pp =+ =+ (21) 5.2 Radius of curvature for biarc curve In the case of biarc curve with same planar centers shown in Fig. 13, the biarc equation of Eq.(19) can be rearranged as the following. 11212cos cos sin sin 1Z =+ (22) ( )2121 1 1 2 222coscos 0RRZ L R R L+= (23) The optimization of biarc curve requires the minimum difference of radii 1(R and 2).R The minimum difference is defined as in Eq.(24) and the radius of 2R is reformed as in Eq.(25). The differentiation of to 1R 1(/ 0)ddR= from Eq.(24) and Eq.(25) gives a quadratic equation as in Eq.(26) and also the radii of arcs 1(R and 2)R can be calculated in Eq.(27) and Eq.(25). ()212R R= (24) ()211211 22cososLRLRZR L=(25) ()2211 1 21221 2124cos2cos cos cos 0ZR LZ RLZ + + =(26) ()2 12111cos 1 cos2LRZ + = (27) In the case of biarc curve with cross planar center as shown in Fig. 14, the biarc equation of Eq.(20) is arranged as in Eq.(28) and Eq.(29). 2 12 12cos cos sin sin 1Z =+ (28) ( )2122 1 1 2 222coscos 0RRZ L R R L+= (29) 12RC1(XC1, YC1)R1R2RC2(XC2, YC2)L12S*Fig. 14 Radii on cross planar centers 12R1R212RC1RC2L(XC2, YC2)(XC1, YC1)S*Fig. 13 Radii on same planar centers ntsINTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 11, No. 3 JUNE 2010 / 425Here, it is assumed that the radii of arcs are proportional to the radial direction angles on biarc span as given in Eq.(31). By solving Eq.(29) and Eq.(30), the radius of 1R is defined as in Eq.(31) and 2R can be calculated in Eq.(30). 1 222112 1;RRR R = (30) ()2111cos cosL AABRB+ + = (31) where 122cos ,A= 1222B Z= 5.3 Reduction of machining points Because the excessive machining points on cam profile can go down the accuracy and efficiency in the machining procedures, the reduction of machini
- 温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。
|
2:不支持迅雷下载,请使用浏览器下载
3:不支持QQ浏览器下载,请用其他浏览器
4:下载后的文档和图纸-无水印
5:文档经过压缩，下载后原文更清晰
|
川公网安备: 51019002004831号