【導(dǎo)讀】：Ⅰ軸和Ⅱ軸嚙合齒輪的計算²²²²²²²²²²²²²²²²²²²²²17. :軸的選用及強(qiáng)度計算和校核²²²²²²²²²²²²²²²²²²²²²²22. 就是在近代的浸出法制油中隊高含。螺旋榨油機(jī)的結(jié)構(gòu)直接影響到油脂生產(chǎn)的數(shù)量和質(zhì)量。而榨油機(jī)的工作部。分是螺旋軸和榨籠構(gòu)成，料胚經(jīng)過螺旋軸和榨籠之間的空間——炸膛，而受到壓榨。油機(jī)的“心臟”，它們的結(jié)構(gòu)直接影響到榨油機(jī)的性能。本文通過了解壓榨機(jī)的資料，然后比對壓榨。旋桿的設(shè)計過程，本文的傳動采用兩級減速傳動，使機(jī)器運(yùn)作穩(wěn)定。通過對整機(jī)功率，轉(zhuǎn)矩，最后。還要對整個設(shè)計重要部件做出校核，能夠讓機(jī)器正常運(yùn)作。在我國，榨油機(jī)的發(fā)展已二十多年，從傳統(tǒng)的榨油設(shè)備，到現(xiàn)在先進(jìn)的榨油機(jī)器，

　　

【正文】 new possible robots. These manipulators respond to the increasing demand of fast working rhythms in modern production at a low cost and are suited for any kind of pick and place jobs like sorting, arranging on palettes, packing and assembly. Keywords: Kinematics, Parallel Robot. Introduction The mathematical theory of groups can be applied to the set of displacements. If we can call {D} the set of all possible displacements, it is proved, according to this theory, that {D} have a group structure. The most remarkable movements of a rigid body are then represented by subgroups of {D}. This method leads to a classification of mechanism [1]. The main step for establishing such a classification is the derivation of an exhaustive inventory of the subgroups of the displacement group. This can be done by a direct reasoning by examining all the kinds of products of rotations and translations [2]. However, a much more effective method consists in using Lie Group Theory [3] , [4]. Lie Groups are defined by analytical transformations depending on a finite number of real parameters. The displacement group {D} is a special case of a Lie Group of dimension six. Lie’s Theory Within the framework of Lie’ Theory, we associate infinitesimal transformations making up a Lie algebra with finite operations which are obtained from the previous ones by exponentiation. Continuous analytical groups are described by the exponential of differential operators which correspond to the infinitesimal transformations of the group. Furthermore, group properties are interpreted by the algebraic structure of Lie algebra of the differential operators and conversely. We recall the main definition axiom of a Lie algebra: a Lie algebra is a vector space endowed with a bilinear skew symmetric closed product. It is 38 well know [5] , that the set of screw velocity fields is a vector space of dimension six for the natural operations at a given point N. By following the steps indicated in [3] we can produce the exhaustive list of the Lie subgroup of Euclidean displacements {D} (see synoptical list 1). This is done by first defining a differential operator associated with the velocity field. Then, by exponentiation, we derive the formal Lie expression of finite displacements which are shown to be equivalent to affine direct orthonormal transformations. Lie subalgebras of screw velocity fields lead to the description of the displacement subgroups. The {X (w)} subgroup In order to generate spatial translation with parallel mechanisms, we are led to look for displacements subgroups the intersection of which is the spatial translation subgroup {T}.We will consider only the cases for which the intersection subgroup is strictly included in the two “parallel” subgroups. The most important case of this sort is the parallel association of two {X (w)} subgroups with two distinct vector directions w and w’. It is easy to prove: {X(w)}? {X(w’)}={T},w≠ w’ The subgroup {X (w)} plays a prominent role in mechanism design. This subgroup bines spatial translation with rotation about a movable axis which remains parallel to given direction w , well defined by the unit vector w. Physical implementations of {X(w)} mechanical liaisons can be obtained by ordering in series kinematics pairs represented by subgroups of {X(w)}. Practically only prismatic pair and a revolute pair P, R, H are use to build robots (the cylindric pair C bines in a pact way a prismatic pair and a revolute pair). A plete list of all possible binations of these kinematics pairs generating the {X (w)} subgroup is given in [6]. Two geometrical conditions have to be satisfied in the series: the rotation axes and the screw axes are parallel to the given vector w。 there is no passive mobility. The displacement operator for the {X {w}} subgroup, acting on point M is: M → N + ａ u + bv + cw +exp(hw^) N M ^ is the symbol of the vector product. Point N and the vectors u, v, w make up an orthogonal frame of reference in the space and a, b, c, h are the four parameters of the subgroup which has the dimension 4. Parallel robots for spatial translation To produce spatial translation it is sufficient to place two mechanical generators of the subgroups {X(w)} and {X(w’)},w≠ w’, in parallel, between a mobile platform and a fixed motors then three generators of the three subgroups {X(w)},{X(w’)},{X(w’’)},w≠ w’, is needed. Any series of P, R or H pairs which constitute a mechanical generator of the {X (w)} subgroup can be implemented. Morever, these three mechanical generators may be different or the same depending on the desired kinematics results. This wide range of binations 39 gives rise to an entire family of robots capable of spatial translation. Simulation of the most interesting architectures can easily be achieved and the choice of the robot to be constructed can therefore meet the needs of the missioner. Clavel’s Delta robot belongs to this family as it is based on the same kinematics principles [7]. The parallel manipulator YSTAR STAR [16] is made up by three cooperating arms which generate the subgroups {X (u)}, {X (u’)}, {X(u’’)}, (fig 1). The three arms are identical and each one generates a subgroup {X(u)} by the series RHPaR where Pa represents the circular translation liaison determined by the two opposite bars of a planar hinged parallelogram. The axes of the two revolute pairs and of the screw pair must be parallel in order to generate a {X (u)}, subgroup. For each arm, the first two pairs, . the coaxial revolute pair and the screw pair, constitute the fixed part of the robot and form at the same time the mechanical structure of an axes lie on the same plane and divide it into three identical parts thus forming a Y shape. Hence the angle between any two axes is always 2? /3. The mobile part of the robot is made up by three PaR series that all converge