Rapid prototyping uses layered manufacturing technology to produce functional parts directly from 3D computer-aided design model without involving any tools and human intervention. Due to layer by layer deposition, volumetric error remains in the part which is basically the volumetric difference between computer-aided design model and the fabricated part. This volumetric error causes poor dimensional accuracy and surface finish, which has limited the widespread applications of rapid prototyping. Although rapid prototyping is able to produce functional parts in less build time with less material wastage, today many industries are looking for better surface quality associated with these parts. Literature discloses that the part quality can be improved by selecting proper build orientation that corresponds to minimum volumetric error. In support of this, current study presents a computer-aided design-based novel methodology to precisely measure the volumetric error in layered manufacturing process, in particular fused deposition modeling process. The proposed method accepts computer-aided design model of the part in .CAT format and automatically calculates volumetric error for different build orientations. An Excel function is integrated with it to determine optimum build orientation based on minimum volumetric error. Several simple and complex examples verified the robustness of our proposed methodology. We anticipate that the current invention will help future rapid prototyping users in producing high-quality products through an intelligent process planning.
Handling of objects with irregular shapes and that of flexible/soft objects by ordinary robot grippers is difficult. Multi fingered gripper may be a solution to such handling tasks. However, dexterous grippers will be the appropriate solution to such problems. Although it is possible to develop robotic hands which can be very closely mapped to human hands, it is sometimes not to be done due to control, manufacturing and economic reasons. The present work aims at designing and developing a dexterous robotic hand for manipulation of objects.
This work describes welding of the sheets with different thickness values and then characterizing the mechanical and microstructural properties for two different types of welding i.e. GMAW and SMAW. The joints are devised in such pattern that the effect of sheet thickness and welding current on these properties can be easily assessed. Initial microstructural studies are carried out with high-resolution optical microscopy and SEM. These images are then processed in ImageJ software to analyze various properties of different phases involved. Mechanical properties like the tensile strength, microhardness, impact energy or toughness are also measured and correlated with the microstructures and welding parameters. The main aim of this project is to design new set of welding parameters for structural steels that are used widely in different construction works and industries. Optimizing the results and choosing the best possible way to get superior properties are the key points.
The growing demand for advanced manufacturing processes calls for reduction in manufacturing cost and manufacturing time. Fused Deposition Modelling (FDM) is one of the rapidly developing rapid Prototyping (RP) process. In this work an effort has made to make FDM process cost effective by replacing solid model with shelled model in-filled with user-defined parametric cellular structures. This approach helps in keeping a balance between material usages, build time and mechanical properties. The proposed method is implemented on a few specimens and results signify that 20-30% expensive build material as well as build time can be saved by this approach. The whole algorithm is based on .STL format, and is coded in MATLAB providing a versatile and widely acceptable platform.
Welding has been done by taking mild steel as work piece material in shielded metal arc welding (SMAW) process. Material thickness and current were considered as input parameters. Joining of metals has been completed in two ways. In first process double pass welding has been done in which 1st pass was in reverse polarity and the second pass was in straight polarity and in the 2nd process both the passes of welding were completed with straight polarity. The comparison of microstructure and impact toughness has been investigated. It was found that more amount of heat was generated in the 2nd process as compared to the 1st process. Therefore, growths of grains in heat affected zone occurred and maximum growth occurred in 2nd than 1st process. Impact strength increased with decrease in current value and increase in material thickness respectively. The impact strength values for 1st process welding were relatively less as compared to 2nd process.
Purpose The purpose of this paper is to develop an efficient hybrid method that can collectively address assembly sequence generation (ASG) and exploded view generation (EVG) problem effectively. ASG is an act of finding feasible collision free movement of components of a mechanical product in accordance with the assembly design. Although the execution of ASG is complex and time-consuming in calculation, it is highly essential for efficient manufacturing process. Because of numerous limitations of the ASG algorithms, a definite method is still unavailable in the computer-aided design (CAD) software, and therefore the explosion of the product is not found to be in accordance with any feasible disassembly sequence (disassembly sequence is reverse progression of assembly sequence). The existing EVG algorithms in the CAD software result in visualization of the entire constituent parts of the product over single screen without taking into consideration the feasible order of assembly operations; thus, it becomes necessary to formulate an algorithm which effectively solves ASG and EVG problem in conjugation. This requirement has also been documented as standard in the “General Information Concerning Patents: 1.84 Standards for drawings” in the United States Patent and Trademark office (2005) which states that the exploded view created for any product should show the relationship or order of assembly of various parts that are permissible. Design/methodology/approach In this paper, a unique ASG method has been proposed and is further extended for EVG. The ASG follows a deterministic approach to avoid redundant data collection and calculation. The proposed method is effectively applied on products which require such feasible paths of disassembly other than canonical directions. Findings The method is capable of organizing the assembly operations as linear or parallel progression of assembly such that the assembly task is completed in minimum number of stages. This result is further taken for EVG and is found to be proven effective. Originality/value Assembly sequence planning (ASP) is performed most of the times considering the geometric feasibility along canonical axes without considering parallel possibility of assembly operations. In this paper, the proposed method is robust to address this issue. Exploded view generation considering feasible ASP is also one of the novel approaches illustrated in this paper.
In product assembly, optimized sequence is a prerequisite for automated systems. The assembly process can be optimized through appropriate selection and allocation of the given tasks in a multi-device framework. These two discrete tasks need to be integrated to produce the optimum result and a cost effective system to cope with the needs of the system, the present work attempts to generate an automatic assembly sequence and seeks for optimal allocation of tasks amongst the available robots. Further, an effective task allocation approach considers the capabilities of the deployable robots. This paper presents an integrated approach for assembly sequence generation and task allocation for multi-robot systems by considering their capability in terms of time and space. An example of a 21 part drive assembly is given to illustrate the concept and procedure of the proposed methodology.
With the advent of new control techniques and development of microactuators, manipulator designers have gained inpetus todevelop manipulators and the related devicesthat is more flexible, responsive, smart and anthropomorphic.Taking cue from the work of a number of researchersover a couple of decades, the present work is a systematic attempt to develop a five fingered anthropomorphic robotic hand with 25 DoFs. The hand closely follows the anatomy of a typical human hand. The paper presents the structure of the proposed hand and its model for kinematic analysis. The kinematic analysis has been carried out using conventional method using MATLab software. The result obtained through the analysis confirmed that the robot hand conforms to the objective. DOI: http://dx.doi.org/10.11591/ijra.v1i2.360 Full Text: PDF
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