Robotic Solutions Applied to Production and Measurement of Marine Propellers

2012 ◽  
Author(s):  
Javier Cavada ◽  
Fernando Fadón
Keyword(s):  
Industrial Robots ◽  
Cell Alignment ◽  
Marine Propellers ◽  
Tool Positioning ◽  
Cad Cam ◽  
Principal Factors ◽  
Propeller Blades ◽  
The Individual ◽  
Accuracy And Repeatability ◽  
Individual Design

Over the past decades, robots have emerged as a valuable technological solution for multiple highly complex industrial processes, and the manufacture of marine propellers has not been an exception. Majority of the propellers being produced worldwide are custom-designed products aiming to satisfy each ship’s propulsion requirements. Such geometrical diversity is a considerable challenge when traditionally manual manufacturing processes like hand-grinding and polishing need to be automated. In several market-leading propeller manufacturers within Europe and Asia, industrial robots are being applied for widely diverse operations such as milling polystyrene blocks to make moulding patterns, grinding out the excess material in the blade surfaces, or polishing the complete propellers’ surface before their final verification. Propeller blades are customized products, formed by curved and warped surfaces, requiring minimum 5 axes to be smoothly polished, and this can be easily achieved with a robot cell where the CAD/CAM data coming from the individual design are directly translated into robotic parameters. While this solution has demonstrated to be perfectly capable to comply with the marine propellers finishing tolerances, which are internationally defined by ISO 484 standard rules [6], robotic solutions for propeller measurement have not been successfully implemented within this specific industry due to reasons like lack of accuracy and repeatability. This paper analyses the root causes behind this problem, identifying the calibration process, the cell alignment method and the tool positioning as the principal factors resulting in this low measuring repeatability. Findings explained by the authors are the outcome of several practical measuring tests made on real marine propellers within ABB and Fanuc robot cells. This paper concludes offering solutions to reduce the inaccuracies caused by the mentioned factors, and recommending what type of marine propellers are more suitable to be measured with industrial robots, on the basis of ISO 484 requirements for each customized design. Moreover, suggestions for further research on this specific measuring application are provided in the concluding chapter.

Improving Efficiency in Robot Assisted Belt Grinding of High Performance Materials

2014 ◽  
Vol 907 ◽  
pp. 139-149 ◽  
Author(s):  
Eckart Uhlmann ◽  
Florian Heitmüller
Keyword(s):  
Gas Turbines ◽  
High Performance ◽  
Scale Effects ◽  
Turbine Blades ◽  
Repair Process ◽  
Industrial Robots ◽  
Robot Assisted ◽  
Belt Grinding ◽  
Economy Of Scale ◽  
The Individual

In gas turbines and turbo jet engines, high performance materials such as nickel-based alloys are widely used for blades and vanes. In the case of repair, finishing of complex turbine blades made of high performance materials is carried out predominantly manually. The repair process is therefore quite time consuming. And the costs of presently available repair strategies, especially for integrated parts, are high, due to the individual process planning and great amount of manually performed work steps. Moreover, there are severe risks of partial damage during manually conducted repair. All that leads to the fact that economy of scale effects remain widely unused for repair tasks, although the piece number of components to be repaired is increasing significantly. In the future, a persistent automation of the repair process chain should be achieved by developing adaptive robot assisted finishing strategies. The goal of this research is to use the automation potential for repair tasks by developing a technology that enables industrial robots to re-contour turbine blades via force controlled belt grinding.

scholarly journals Characterisation of the Filler Fraction in CAD/CAM Resin-Based Composites

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1986
Author(s):  
Andreas Koenig ◽  
Julius Schmidtke ◽  
Leonie Schmohl ◽  
Sibylle Schneider-Feyrer ◽  
Martin Rosentritt ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Point Of View ◽  
Specific Information ◽  
Dental Resin ◽  
X Ray ◽  
Computer Aided ◽  
Cad Cam ◽  
Filler Fraction ◽  
The Individual ◽  
Aided Design

The performance of dental resin-based composites (RBCs) heavily depends on the characteristic properties of the individual filler fraction. As specific information regarding the properties of the filler fraction is often missing, the current study aims to characterize the filler fractions of several contemporary computer-aided design/computer-aided manufacturing (CAD/CAM) RBCs from a material science point of view. The filler fractions of seven commercially available CAD/CAM RBCs featuring different translucency variants were analysed using Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS), Micro-X-ray Computed Tomography (µXCT), Thermogravimetric Analysis (TG) and X-ray Diffractometry (XRD). All CAD/CAM RBCs investigated included midifill hybrid type filler fractions, and the size of the individual particles was clearly larger than the individual specifications of the manufacturer. The fillers in Shofu Block HC featured a sphericity of ≈0.8, while it was <0.7 in all other RBCs. All RBCs featured only X-ray amorphous phases. However, in Lava Ultimate, zircon crystals with low crystallinity were detected. In some CAD/CAM RBCs, inhomogeneities (X-ray opaque fillers or pores) with a size <80 µm were identified, but the effects were minor in relation to the total volume (<0.01 vol.%). The characteristic parameters of the filler fraction in RBCs are essential for the interpretation of the individual material’s mechanical and optical properties.

Surface Roughness of Two CAD/CAM Restorative Materials as Affected by Chewing Simulation v1

2022 ◽  
Author(s):  
eaeldwakhly not provided
Keyword(s):  
Surface Roughness ◽  
Computer Aided Design ◽  
Surface Characteristics ◽  
Ceramic Materials ◽  
Study Groups ◽  
Significance Level ◽  
Chewing Simulation ◽  
Computer Aided ◽  
Cad Cam ◽  
The Individual

This study was conducted to assess the surface characteristics in terms of roughness of two CAD/CAM (Computer-Aided-Design/Computer-Aided Manufacturing)restorative material spre and post chewing simulation exposure. Methods: Specimens were prepared from two CAD/CAM ceramic materials: Cerec Blocs C and IPS e-max ZirCAD. A total of 10 disks were prepared for each study group. 3D optical noncontact surface profiler was used to test the surface roughness (ContourGT, Bruker, Campbell, CA, USA). A silicone mold was used to fix the individual samples using a self-curing resin. Surface roughness (SR) was examined pre and post exposure to chewing simulation. 480,000 simulated chewing cycles were conducted to mimic roughly two years of intraoral clinical service. The results data was first tested for normality and equal variance (Levene’s test >0.05) then examined with paired and independent sample t-test at a significance level of (p < 0.05). Results:The two CAD-CAM materials tested exhibited increased surface roughness from baseline. The highest mean surface roughness was observed in Cerec blocs C group after chewing simulation (2.34 µm± 0.62 µm). Whereas the lowest surface roughness was observed in IPS e.max ZirCAD group before chewing simulation (0.42 µm± 0.16 µm). Both study groups exhibited significantly different surface roughness values (p< 0.05). There was a statistically higher surface roughness values after the chewing simulation in Cerec blocs C when compared to IPS e.max ZirCAD groups (p = 0.000).Conclusion:Even though both tested CAD/CAM materials differ in recorded surface roughness values, results were within clinically accepted values.

Numerical Study on Multiple-Blade-Rate Unsteady Propeller Forces for Underwater Vehicles

2021 ◽  
pp. 1-20
Author(s):  
Kenshiro Takahashi ◽  
Jun Arai ◽  
Takayuki Mori
Keyword(s):  
Numerical Study ◽  
Underwater Vehicles ◽  
Marine Propellers ◽  
Defense Systems ◽  
Detection Technology ◽  
Acoustic Signature ◽  
Océanographic Survey ◽  
Propeller Blades ◽  
Marine Vessels ◽  
Blade Loads

The unsteady propeller forces of an underwater vehicle were numerically simulated using computational fluid dynamics to investigate the effects of the axial location of the stern planes. A benchmark study was undertaken using a three-bladed propeller; experimental results of the nominal inflow wake profile were analyzed and the unsteady propeller forces were measured. The numerical method was applied to predict the unsteady propeller forces in the SUBOFF model’s wake by varying the axial locations of the stern planes. Several remarks were made on the primary harmonics of the hull’s wakes and blade-rate propeller forces. Introduction The hydroacoustic noise, which matches multiples of the number of propeller blades and its rotational speed, known as “blade-rate (BR) noise,” has been increasingly used to manage hydroacoustics for naval vessels. BR noise can be caused by alternating blade loads owing to fluctuations in the angle of attack of the blades because marine propellers are operated in the nonuniform wake of ships’ hulls. The unsteady blade load produces unsteady propeller forces that are transmitted via the propeller shaft and bearing, thus producing undesirable vibration and noise. Although the resultant BR noise is a common issue for marine vessels, in particular, submarines and other underwater vehicles deployed for undersea defense systems and oceanographic survey systems require strict specifications for the acoustic signature. Therefore, the unsteady propeller forces must be improved for reduced detectability, because the vehicles should be able to operate without being discovered while sonar detection technology continues to improve.

Effect of Testing Conditions on Performance and Durability of Stabilisers in Plastics

2003 ◽  
Vol 11 (2) ◽  
pp. 81-90 ◽  
Author(s):  
J. Pospíšil ◽  
Z. Horák ◽  
J. Pilař ◽  
S. Nešpurek ◽  
N. C. Billingham ◽  
...  
Keyword(s):  
Thermal Aging ◽  
Material Properties ◽  
Activation Energies ◽  
Physical Processes ◽  
Factors Affecting ◽  
Testing Conditions ◽  
Testing Method ◽  
Principal Factors ◽  
The Individual ◽  
Accelerated Thermal Aging

The accelerated thermal aging and weathering of stabilised plastics provides information on stabiliser efficiency and polymer durability more quickly than natural testing. This allows the monitoring of the material properties of plastics in the foreseen application environment and the development of new stabilisation formulations. The harshness of the testing method affects the individual processes involved regarding their activation energies and mechanisms, the physical relations in the polymer – stabiliser system, and the chemical and physical processes accounting for the consumption of stabilisers. The principal factors affecting any comparison of accelerated results with natural testing are outlined.

scholarly journals INVESTIGATION OF FIT OF THE INDIVIDUAL ABUTMENT TO THE VARIOUS PLATFORMS OF IMPLANTS ON SAGITTAL SECTION

2019 ◽  
Vol 15 (2) ◽  
pp. 106-109
Author(s):  
Константин Саркисян ◽  
Konstantin Sarkisyan ◽  
Мария Стрижакова ◽  
Maria Strizhakova ◽  
В. Стрижаков ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Three Dimensional ◽  
Marginal Fit ◽  
Different Types ◽  
Volumetric Images ◽  
Cad Cam ◽  
Inflammatory Processes ◽  
Sagittal Slice ◽  
Grinding Machine ◽  
The Individual

Introduction. Modern implant systems have different types of connections between the implant and the abutment, in the area of which a microgap can be constructively formed, as a result of which dentists are faced with a loss of bone tissue and inflammatory processes in the area of dental implants. Objectives ― assessment of the accuracy of the marginal fit of an individual abutment to the implant platform on a sagittal slice. Methods. Two groups were formed according to the type of connection between the implant and the abutment (conical and planar). Individual abutments for all systems were made using CAD-CAM technology. Using the grinding machine Metaserv 25, sagittal sections of the abutment and implant were obtained. The study and cutting the compound was carried out on a TESCAN MIRA 3 autoemission electron microscope. Results. Using an electron microscope TESCAN MIRA 3, we obtained images of the surface of the connection of the abutment and the implant on a sagittal slice. When three-dimensional scanning of the studied samples were obtained volumetric images. Measurements of the microgap of the implant compound and abutment on the sagittal split showed that with an increase of x8000 in the first group with a conical connection, the figure varied from 0.27-3.46 microns. In the second group with a planar compound, the index varied from 6.50-9.70 microns. Conclusions. The ratio of the abutment to the implant with conical connections showed the best results in comparison with planar connections. Using CAD-CAM technology allows you to create prostheses with good marginal fit of the connection between the implant and the abutment.

Benefit Evaluation for Manufacturing of Marine Propellers

2008 ◽  
Author(s):  
Der-Min Tsay ◽  
Hsin-Pao Chen ◽  
Sa´ndor Vajna ◽  
Michael Schabacker
Keyword(s):  
Cost Model ◽  
Cost Savings ◽  
Machining Efficiency ◽  
Machining Time ◽  
Marine Propellers ◽  
Tool Paths ◽  
Benefit Evaluation ◽  
Cad Cam ◽  
Increase Productivity ◽  
The Cost

To increase productivity of marine propellers by raising machining efficiency, this paper presents the zigzag/spiral tool paths generation algorithm based on the arc base curve approach for three-axis machining of curved surfaces of propellers. By considering the shapes of selected cutters with different types of tool paths generated by the proposed procedure, machining efficiency can be calculated and simulated. To verify the accuracy and effectiveness of the developed approach, numerical and experimental results of machining of propeller surfaces are compared. It was proved that the machining time can be cut down up to 19% by using zigzag tool paths with a toroidal cutter. In addition, the machining knowledge revealed here can be accumulated for benefit evaluation in the manufacturing process with existing CAD/CAM systems. From the cost model, design, and process views, the overall cost savings after 5 years are investigated, and the expected benefit yield is about 45%.

Design Features of MAN B&W Medium Speed Diesel Engines Optimizing Life Cycle Costs

2001 ◽  
Author(s):  
Georg Wachtmeister ◽  
Horst W. Koehler
Keyword(s):  
Life Cycle ◽  
Diesel Engines ◽  
Life Cycle Costs ◽  
Medium Speed ◽  
Fuel Oils ◽  
Heavy Fuel Oils ◽  
Main Components ◽  
The Individual ◽  
Exhaust Gas Emissions ◽  
Individual Design

Abstract It is not only fuel and lube oil costs which determine life cycle costs of a diesel engine, but also maintenance costs and costs for replacements of wear components. All these costs are linked to the individual design of the engine and its capability to burn a variety of fuels, including low-priced heavy fuel oils. As an example, the paper describes several main components of MAN B&W medium-speed diesel engines (engine block, liner, piston) and how they contribute to lower life cycle costs by easier maintenance procedures, longer TBOs and longer life times. To achieve this is a challenging task for the engine manufacturer, since other strong market requirements such as reduced exhaust gas emissions or high power density have to be fulfilled simultaneously.

High Technology in Shipbuilding

1987 ◽  
Vol 201 (2) ◽  
pp. 59-72 ◽  
Author(s):  
P A Milne
Keyword(s):  
Computer Program ◽  
High Technology ◽  
Industrial Robots ◽  
Shipbuilding Industry ◽  
Delivery Times ◽  
Cad Cam ◽  
Computer Based ◽  
Reduced Costs ◽  
Engine Construction

Following a review of market developments and their dramatic effects on shipbuilders, the paper makes a case for a continuing shipbuilding industry in Europe, and reviews the investment in high technology equipment in merchant shipyards. The introduction of computer-based systems in the industry and the extensive use of CAD/CAM in shipyards are described. The use and potential of industrial robots and lasers are covered. Advances in engine construction and ship production resulting in shorter delivery times and reduced costs are illustrated. Engine selection by computer program is described and the paper concludes with a view on future changes in merchant shipbuilding.

scholarly journals A Comparison of Physical and Numerical Modeling of Homogenous Isotropic Propeller Blades

2020 ◽  
Vol 8 (1) ◽  
pp. 21 ◽  
Author(s):  
Luca Savio ◽  
Lucia Sileo ◽  
Sigmund Kyrre Ås
Keyword(s):  
Numerical Modeling ◽  
Open Water ◽  
Computational Approach ◽  
Experimental Setup ◽  
Fluid Structure ◽  
Towing Tank ◽  
Design Procedures ◽  
Structure Interaction ◽  
Marine Propellers ◽  
Propeller Blades

Results of the fluid-structure co-simulations that were carried out as part of the FleksProp project are presented. The FleksProp project aims to establish better design procedures that take into account the hydroelastic behavior of marine propellers and thrusters. Part of the project is devoted to establishing good validation cases for fluid-structure interaction (FSI) simulations. More specifically, this paper describes the comparison of the numerical computations carried out on three propeller designs that were produced in both a metal and resin variant. The metal version could practically be considered rigid in model scale, while the resin variant would show measurable deformations. Both variants were then tested in open water condition at SINTEF Ocean’s towing tank. The tests were carried out at different propeller rotational speeds, advance coefficients, and pitch settings. The computations were carried out using the commercial software STAR-CCM+ and Abaqus. This paper describes briefly the experimental setup and focuses on the numerical setup and the discussion of the results. The simulations agreed well with the experiments; hence, the computational approach has been validated.

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