NOVEL COMPOUND-SPHERE-JOINT AND ITS

APPLICATION IN PARALLEL MACHINE TOOL

Zhang Lijie  Li Yongquan  Huang Zhen

(School of Mechanical Engineering, Yanshan University, Qinhuangdao 066004)

Abstract: A novel parallel machine-tool mechanism based on the compound-sphere-joint is presented. The parallel machine tool consists of a moving spindle system and a fix base connected by 5-SPS serial chains. The moving spindle system is made up of two compound-sphere-joints, one of them is a three-layer sphere-joint connecting three SPS serial chains; the other is a two-layer sphere-joint connecting two SPS serial chains. The two-sphere-joints spindle system replaces the general moving platform and the main axis of the parallel machine tool is collinear with the centerline of two sphere-joints. Compared with Stewart platform, the novel 5-SPS parallel machine tool has the same necessary degree-of-freedom, and its structure will be simple and has decoupling of the position and orientation. In addition, inverse position resolution is convenient, and its control is easier. The novel structure of the parallel machine tool is proposed, and the structure of the compound-sphere-joint is analyzed. Inverse position resolution is obtained. Posing reachable workspace is also analyzed and calculated. The novel parallel mechanism machine tool has a wide prospective outlook in three-dimension surface manufacturing fields. 

Key words: Compound-sphere-joint  Parallel mechanism  Inverse position resolution  Reachable workspace

CLC No: TP242  TG659

河北省自然科学基金资助项目(E2004000230). Received 20050218, received in revised form 20050725