The top relief surfaces of an hourglass worm gear hob are ground manually in the traditional manufacturing process,which cannot ensure the width of the land surfaces of the hob.Moreover,each geometric feature of the h...The top relief surfaces of an hourglass worm gear hob are ground manually in the traditional manufacturing process,which cannot ensure the width of the land surfaces of the hob.Moreover,each geometric feature of the hob has been produced through different manufacturing techniques and machine tools,which results in low efficiency.To solve this problem,we propose a semi-automatic computer aided design(CAD)method for hobs.The point clouds of each feature surface of a hob are calculated by combing mathematical equations of the top relief surfaces built by the proposed method with other existing equations of hob surfaces.According to the point clouds,the method can achieve the automatic modeling for the hob in three-dimensional(3D)software by classifying and extracting the parameter information of the feature-hierarchical knowledge of the hob.Based on the generated 3D model,the entire surfaces of the hob can be manufactured on a four-axis computer numerical control(CNC)milling machine through only twice clamping.Verification of the width of the land surface of the hob manufactured by semi-automatic CAD method on a measuring projector proved the precision of the designed width can be ensured.The edge of the contact area on the worm wheel in a meshing experiment is clear and distinct,which means the worm gear drive is meshed well and the hob manufactured by the proposed method has improved machinability.The method simplifies the processing technique,and improves the design efficiency and production accuracy.展开更多
Two case studies,referring to historic Italian buildings housing city halls,provide an opportunity to investigate the design of non-standard elements aimed at protecting masonry vaults,with particular reference to the...Two case studies,referring to historic Italian buildings housing city halls,provide an opportunity to investigate the design of non-standard elements aimed at protecting masonry vaults,with particular reference to the preliminary works prior to the actual structural restoration work.There is in fact a phase in which it is a priority to secure the vault to avert possible risks to the users of that portion of the building.This phase is temporarily intermediate between the detection and aggravation of injuries and the renovation and consolidation project.Although these are provisional works,they are intended for buildings that are often public and therefore intended for a wide range of users,such as schools,offices or monumental buildings.In analyzing traditional techniques and systems used in similar cases,the possibility of developing evolutionary aspects with respect to,above all,simple shoring techniques emerged.In these areas,hybrids between a structural and architectural project,it is possible to reconcile static requirements with architectural techniques of space management,attentive to the quality of the interior and the integration of the provisional work with the reference context.展开更多
基金supported by The Development of Design and Manufacturing Technology of Double-Enveloping Worm Pair in High-precision with Little Centre Distance(No.69190135)We would like to thank the Professor Workstation of China Agricultural University in Hebei Baoding Laibo Transmission Machinery Manufacturing Co.LTD(No.20200901).
文摘The top relief surfaces of an hourglass worm gear hob are ground manually in the traditional manufacturing process,which cannot ensure the width of the land surfaces of the hob.Moreover,each geometric feature of the hob has been produced through different manufacturing techniques and machine tools,which results in low efficiency.To solve this problem,we propose a semi-automatic computer aided design(CAD)method for hobs.The point clouds of each feature surface of a hob are calculated by combing mathematical equations of the top relief surfaces built by the proposed method with other existing equations of hob surfaces.According to the point clouds,the method can achieve the automatic modeling for the hob in three-dimensional(3D)software by classifying and extracting the parameter information of the feature-hierarchical knowledge of the hob.Based on the generated 3D model,the entire surfaces of the hob can be manufactured on a four-axis computer numerical control(CNC)milling machine through only twice clamping.Verification of the width of the land surface of the hob manufactured by semi-automatic CAD method on a measuring projector proved the precision of the designed width can be ensured.The edge of the contact area on the worm wheel in a meshing experiment is clear and distinct,which means the worm gear drive is meshed well and the hob manufactured by the proposed method has improved machinability.The method simplifies the processing technique,and improves the design efficiency and production accuracy.
文摘Two case studies,referring to historic Italian buildings housing city halls,provide an opportunity to investigate the design of non-standard elements aimed at protecting masonry vaults,with particular reference to the preliminary works prior to the actual structural restoration work.There is in fact a phase in which it is a priority to secure the vault to avert possible risks to the users of that portion of the building.This phase is temporarily intermediate between the detection and aggravation of injuries and the renovation and consolidation project.Although these are provisional works,they are intended for buildings that are often public and therefore intended for a wide range of users,such as schools,offices or monumental buildings.In analyzing traditional techniques and systems used in similar cases,the possibility of developing evolutionary aspects with respect to,above all,simple shoring techniques emerged.In these areas,hybrids between a structural and architectural project,it is possible to reconcile static requirements with architectural techniques of space management,attentive to the quality of the interior and the integration of the provisional work with the reference context.
