曲柄(導(dǎo)桿)滑塊機(jī)構(gòu)設(shè)計(jì)分析外文翻譯-其他專業(yè)(編輯修改稿)
2025-02-24 12:21 本頁(yè)面
【文章內(nèi)容簡(jiǎn)介】 ing in no uncertain terms, and the mechanism will only move because the rigid links flex and twist, producing loads in the bearings. If the axes are nearly parallel, the mechanism operates because of the looseness of the running fits of the bearings or flexibility of the links. A mon way of pensating for small no parallelism is to connect the links with selfaligning bearings, actually spherical joints allowing threedimensional rotation. Such a planar linkage is thus a lowgrade spatial linkage. Degrees of Freedom A threebar linkage (containing three bars linked together) is obviously a rigid frame。 no relative motion between the links is possible. To describe the relative positions of the links in a fourbar linkage it is necessary only to know the angle between any two of the links. This linkage is said to have one degree of freedom. Two angles are required to specify the relative positions of the links in a fivebar linkage。 it has two degrees of freedom. Linkages with one degree of freedom have constrained motion。 i. e., all points on all of the links have paths on the other links that are fixed and determinate. The paths are most easily obtained or visualized by assuming that, the link on which the paths are required is fixed, and then moving the other links in a manner patible with the constraints. FourBar Mechanisms When one of the members of a constrained linkage is fixed, the linkage bees a mechanism capable of performing a useful mechanical function in a machine. On pinconnected linkages the input (driver) and output (follower) links are usually pivotally connected to the fixed link。 the connecting links (couplers) are usually neither inputs nor outputs. Since any of the links can be fixed, if the links are of different lengths, four mechanisms, each with a different inputoutput relationship, can be obtained with a fourbar linkage. These four mechanisms are said to be inversions of the basic linkage. SliderCrank Inversions When one of the pin connections in a fourbar linkage is replaced by a sliding joint, a number of useful mechanisms can be obtained from the resulting in Fig. 1 (top) the connection between links 1 and 4 is a sliding joint that permits block 4 to slide in the slot in link 1. It would make no difference, kinematically, if link 1 were sliding in a hole or slot in link 4. If link 1 in Fig. 1 (top) is fixed, the resulting slidercrank mechanism is shown in Fig
高考資料相關(guān)推薦
鄂ICP備17016276號(hào)-1