已阅读5页,还剩2页未读, 继续免费阅读
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
NOVEL METHOD OF REALIZING THE OPTIMAL TRANSMISSION OF THE CRANK-AND-ROCKER MECHANISM DESIGN Abstract: A novel method of realizing the optimal transmission of the crank-and-rocker mechanism is presented. The optimal combination design is made by finding the related optimal transmission parameters. The diagram of the optimal transmission is drawn. In the diagram, the relation among minimum transmission angle, the coefficient of travel speed variation, the oscillating angle of the rocker and the length of the bars is shown, concisely, conveniently and directly. The method possesses the main characteristic. That it is to achieve the optimal transmission parameters under the transmission angle by directly choosing in the diagram, according to the given requirements. The characteristics of the mechanical transmission can be improved to gain the optimal transmission effect by the method. Especially, the method is simple and convenient in practical use. Keywords:Crank-and-rocker mechanism, Optimal transmission angle, Coefficient of travel speed variation INTRODUCTION By conventional method of the crank-and-rocker design, it is very difficult to realize the optimal combination between the various parameters for optimal transmission. The figure-table design method introduced in this paper can help achieve this goal. With given conditions, we can, by only consulting the designing figures and tables, get the relations between every parameter and another of the designed crank-and-rocker mechanism. Thus the optimal transmission can be realized. The concerned designing theory and method, as well as the real cases of its application will be introduced later respectively. 1. ESTABLISHMENT OF DIAGRAM FOR OPTIMAL TRANSMISSION DESIGN It is always one of the most important indexes that designers pursue to improve the efficiency and property of the transmission. The crank-and-rocker mechanism is widely used in the mechanical transmission. How to improve work ability and reduce unnecessary power losses is directly related to the coefficient of travel speed variation, the oscillating angle of the rocker and the ratio of the crank and rocker. The reasonable combination of these parameters takes an important effect on the efficiency and property of the mechanism, which mainly indicates in the evaluation of the minimum transmission angle. The aim realizing the optimal transmission of the mechanism is how to find the maximum of the minimum transmission angle. The design parameters are reasonably combined by the method of lessening constraints gradually and optimizing separately. Consequently, the complete constraint field realizing the optimal transmission is established. The following steps are taken in the usual design method. Firstly, the initial values of the length of rocker 3l and the oscillating angle of rocker are given. Then the value of the coefficient of travel speed variation K is chosen in the permitted range. Meanwhile, the coordinate of the fixed hinge of crank Apossibly realized is calculated corresponding to value K. 1.1 Length of bars of crank and rocker mechanism As shown in Fig.1, left arc GC2 is the permitted field of point A. The coordinates of point A are chosen by small step from point 2C to point G. The coordinates of point A are 02hyycA (1) 22 A AyRx (2) where 0 h, the step, is increased by small increment within range(0,H). If the smaller the chosen step is, the higher the computational precision will be. R is the radius of the design circle. d is the distance from 2 C to G. 2 c o s) 2 c o s (2 2 c o s 33 lRld (3) Calculating the length of arc 1 AC and 2 AC, the length of the bars of the mechanism corresponding to point A is obtained1,2. 1.2 Minimum transmission angle min Minimum transmission angle min (see Fig.2) is determined by the equations3 32 2 14 2 3 2 2 m i n 2 )( c o s ll llll (4) 32 2 14 2 3 2 2 m a x 2 )( c o s ll llll (5) m a xm i n 180 (6) where 1 lLength of crank(mm) 2 lLength of connecting bar(mm) 3 lLength of rocker(mm) 4 lLength of machine frame(mm) Firstly, we choose minimum comparing min with min . And then we record all values of min greater than or equal to 40 and choose the maximum of them. Secondly, we find the maximum of min corresponding to any oscillating angle which is chosen by small step in the permitted range (maximum of min is different oscillating angle and the coefficient of travel speed variation K). Finally, we change the length of rocker 3 l by small step similarly. Thus we may obtain the maximum of min corresponding to the different length of bars, different oscillating angle and the coefficient of travel speed variation K. Fig.3 is accomplished from Table for the purpose of diagram design. It is worth pointing out that whatever the length of rocker 3 l is evaluated, the location that the maximum of min arises is only related to the ratio of the length of rocker and the length of machine frame 3 l/ 4 l, while independent of 3 l. 2. DESIGN METHOD 2.1 Realizing the optimal transmission design given the coefficient of travel speed variation and the maximum oscillating angle of the rocker The design procedure is as follows. (1) According to given K and , taken account to the formula the extreme included angle is found. The corresponding ratio of the length of bars 3 l/ 4 l is obtained consulting Fig.3. 180 1 1 K K (7) (2) Choose the length of rocker 3 l according to the work requirement, the length of the machine frame is obtained from the ratio 3 l/ 4 l. (3) Choose the centre of fixed hinge D as the vertex arbitrarily, and plot an isosceles triangle, the side of which is equal to the length of rocker 3 l(see Fig.4), and 21DC C. Then plot 212 CCMC, draw NC1, and make angle 90 12 NCC. Thus the point of intersection of MC2 and NC1 is gained. Finally, draw the circumcircle of triangle 21C PC. (4) Plot an arc with point D as the centre of the circle, 4 l as the radius. The arc intersections arc GC2 at point A. Point A is just the centre of the fixed hinge of the crank. Therefore, from the length of the crank 2/ )( 211 ACACl (8) and the length of the connecting bar 112 lACl (9) we will obtain the crank and rocker mechanism consisted of 1 l, 2 l, 3 l, and 4 l.Thus the optimal transmission property is realized under given conditions. 2.2 Realizing the optimal transmission design given the length of the rocker (or the length of the machine frame) and the coefficient of travel speed variation We take the following steps. (1) The appropriate ratio of the bars 3 l/ 4 l can be chosen according to given K. Furthermore, we find the length of machine frame 4 l(the length of rocker 3 l). (2) The corresponding oscillating angle of the rocker can be obtained consulting Fig.3. And we calculate the extreme included angle . Then repeat (3) and (4) in section 2.1 3. DESIGN EXAMPLE The known conditions are that the coefficient of travel speed variation 1818. 1K and maximum oscillating angle 40. The crankandrocker mechanism realizing the optimal transmission is designed by the diagram solution method presented above. First, with Eq.(7), we can calculate the extreme included angle 15. Then, we find 93. 0/ 43 ll consulting Fig.3 according to the values of and . If
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。
最新文档
- 智慧旅游与乡村振兴的融合
- 腹痛拒按的生物标记物探索与临床应用
- 前阴微环境与宫内感染
- 企业关系维护与拓展服务合同
- 企业信息技术项目物联网服务合同
- 人工智能辅助金融风险评估系统合同
- 分销品牌在线声誉管理
- 人工智能安全监控系统开发合同
- 损耗及保鲜技术提升
- 2024-2030年中国工业机器人仿真软件(OLP)行业现状态势与前景趋势预测研究报告
- 小学、初中英语语法比较级和最高级的用法
- 中药学电子版教材
- 山景系列产品包发布1入门和选型ap8264p2数据手册prelimiary v
- 柱承载力计算表格
- 人教版PEP小学英语四年级上册Unit1-单元测试卷及答案共4套
- GB/T 38315-2019社会单位灭火和应急疏散预案编制及实施导则
- 2022年08月四川省绵阳市绵投置地有限责任公司公开招聘员工的21黑钻模拟题3套1000题含答案详解
- 如何提高成本意识 课件
- GB 18447.1-2008拖拉机安全要求第1部分:轮式拖拉机
- 锂离子电池粘结剂总结ATLCATL课件
- 中级美容师理论知识考试试题含答案
评论
0/150
提交评论