Manufacturing features represent area of interest on the machinable surface of a part, which can provide a unique set of removable volumes from part. Feature description in standard for exchange of product(STEP) AP224...Manufacturing features represent area of interest on the machinable surface of a part, which can provide a unique set of removable volumes from part. Feature description in standard for exchange of product(STEP) AP224 is an efficient neutral format for the development of feature based process planning. Process planning information of features can be converted to numerical control(NC)code to have complete manufacturing information of part. STEP-NC code provides an efficient manufacturing information model compared to G-M codes. In this work, an interface is developed for extraction of feature information available in AP224(AIM) format and the ruled-based approach is used to select different process planning parameters. A graphical user interface(GUI) is developed for the interface for displaying features information as represented in AP224 file. Furthermore, the interface generates STEP-NC code in AP238 format. The developed interface has three modules. 1) Module I: Reading interface for STEP AP224 file and development of GUI. 2)Module II: Selection of feature based process planning parameters. 3) Module III: Writing interface for STEP-NC(AP238). The developed interface has been implemented in Java through Java standard data access interface(JSDAITM). The generated STEP-NC AP238 code for the test part has been successfully simulated on STEP-NC Machine TM, an AP238 simulator. This article also provides an in-depth view of application interpreted model(AIM) representation format of STEP for AP224 and AP238.展开更多
Fixture design and planning is one of the most important manufacturing activities, playing a pivotal role in deciding the lead time for product development. Fixture design, which affects the part-quality in terms of g...Fixture design and planning is one of the most important manufacturing activities, playing a pivotal role in deciding the lead time for product development. Fixture design, which affects the part-quality in terms of geometric accuracy and surface finish, can be enhanced by using the product manufacturing information(PMI) stored in the neutral standard for the exchange of product model data(STEP) file, thereby integrating design and manufacturing. The present paper proposes a unique fixture design approach, to extract the geometry information from STEP application protocol(AP) 242 files of computer aided design(CAD) models, for providing automatic suggestions of locator positions and clamping surfaces. Automatic feature extraction software "FiXplan", developed using the programming language C#, is used to extract the part feature, dimension and geometry information. The information from the STEP AP 242 file is deduced using geometric reasoning techniques, which in turn is utilized for fixture planning. The developed software is observed to be adept in identifying the primary, secondary, and tertiary locating faces and locator position configurations of prismatic components. Structural analysis of the prismatic part under different locator positions was performed using commercial finite element method software, ABAQUS, and the optimized locator position was identified on the basis of minimum deformation of the workpiece.The area-ratio(base locator enclosed area(%)/work piece base area(%)) for the ideal locator configuration was observed as 33%. Experiments were conducted on a prismatic workpiece using a specially designed fixture, for different locator configurations. The surface roughness and waviness of the machined surfaces were analysed using an Alicona non-contact optical profilometer. The best surface characteristics were obtained for the surface machined under the ideal locator positions having an area-ratio of 33%, thus validating the predicted numerical results. The efficiency, capability and applicability of the developed software is demonstrated for the finishing operation of a sensor cover – a typical prismatic component having applications in the naval industry, under different locator configurations.The best results were obtained under the proposed ideal locator configuration of area-ratio 33%.展开更多
文摘Manufacturing features represent area of interest on the machinable surface of a part, which can provide a unique set of removable volumes from part. Feature description in standard for exchange of product(STEP) AP224 is an efficient neutral format for the development of feature based process planning. Process planning information of features can be converted to numerical control(NC)code to have complete manufacturing information of part. STEP-NC code provides an efficient manufacturing information model compared to G-M codes. In this work, an interface is developed for extraction of feature information available in AP224(AIM) format and the ruled-based approach is used to select different process planning parameters. A graphical user interface(GUI) is developed for the interface for displaying features information as represented in AP224 file. Furthermore, the interface generates STEP-NC code in AP238 format. The developed interface has three modules. 1) Module I: Reading interface for STEP AP224 file and development of GUI. 2)Module II: Selection of feature based process planning parameters. 3) Module III: Writing interface for STEP-NC(AP238). The developed interface has been implemented in Java through Java standard data access interface(JSDAITM). The generated STEP-NC AP238 code for the test part has been successfully simulated on STEP-NC Machine TM, an AP238 simulator. This article also provides an in-depth view of application interpreted model(AIM) representation format of STEP for AP224 and AP238.
基金Department of Science and Technology,Government of India for providing financial support under the scheme FIST(No.SR/FST/ETI-388/2015)。
文摘Fixture design and planning is one of the most important manufacturing activities, playing a pivotal role in deciding the lead time for product development. Fixture design, which affects the part-quality in terms of geometric accuracy and surface finish, can be enhanced by using the product manufacturing information(PMI) stored in the neutral standard for the exchange of product model data(STEP) file, thereby integrating design and manufacturing. The present paper proposes a unique fixture design approach, to extract the geometry information from STEP application protocol(AP) 242 files of computer aided design(CAD) models, for providing automatic suggestions of locator positions and clamping surfaces. Automatic feature extraction software "FiXplan", developed using the programming language C#, is used to extract the part feature, dimension and geometry information. The information from the STEP AP 242 file is deduced using geometric reasoning techniques, which in turn is utilized for fixture planning. The developed software is observed to be adept in identifying the primary, secondary, and tertiary locating faces and locator position configurations of prismatic components. Structural analysis of the prismatic part under different locator positions was performed using commercial finite element method software, ABAQUS, and the optimized locator position was identified on the basis of minimum deformation of the workpiece.The area-ratio(base locator enclosed area(%)/work piece base area(%)) for the ideal locator configuration was observed as 33%. Experiments were conducted on a prismatic workpiece using a specially designed fixture, for different locator configurations. The surface roughness and waviness of the machined surfaces were analysed using an Alicona non-contact optical profilometer. The best surface characteristics were obtained for the surface machined under the ideal locator positions having an area-ratio of 33%, thus validating the predicted numerical results. The efficiency, capability and applicability of the developed software is demonstrated for the finishing operation of a sensor cover – a typical prismatic component having applications in the naval industry, under different locator configurations.The best results were obtained under the proposed ideal locator configuration of area-ratio 33%.
