Articoli di riviste: "Freeformer"

1

Fateri, Miranda, João Falcão Carneiro, Constantin Schuler, João Bravo Pinto, Fernando Gomes de Almeida, Udo Grabmeier, Tobias Walcher e Michael Salinas. "Impact of 3D Printing Technique and TPE Material on the Endurance of Pneumatic Linear Peristaltic Actuators". Micromachines 13, n. 3 (28 febbraio 2022): 392. http://dx.doi.org/10.3390/mi13030392.

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In this paper, additive manufacturing was used in order to produce hose prototypes for peristaltic linear pneumatic actuators. In order to optimise the endurance of the actuator, we 3D printed different thermoplastic polyurethane elastomers with different shore hardness levels using ARBURG Plastic Freeforming technology. Furthermore, effects of the hose geometries on the lifetime of the actuator were investigated. Experimental evidence showed that the lifetime of the actuator was dependent on the combination of the hose design and on the material used to manufacture the hose. Moreover, experimental tests showed that the use of the Aurburg-Freeformer 3D printing technology led to a much higher hose endurance than the one reported by using the fused layer manufacturing technique.

2

Ceskova, Martina, e Petr Lenfeld. "POLYMER CAVITY MADE BY FREEFORMER® 3D PRINTER: AN INFLUENCE ON INJECTION MOULDED PARTS". MM Science Journal 12, n. 2018 (12 dicembre 2018): 2710–14. http://dx.doi.org/10.17973/mmsj.2018_12_2018125.

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Giacoppo, Giuliano A., Julia Hötzel e Peter P. Pott. "Additively Manufactured Porous Filling Pneumatic Network Actuator". Actuators 12, n. 11 (7 novembre 2023): 414. http://dx.doi.org/10.3390/act12110414.

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This research project investigated the additive manufacturing of pneumatic actuators based on the principle of droplet dosing using an Arburg Freeformer 300-3X 3D printer. The developed structure consists of a porous inner filling and a dense, airtight chamber. By selectively varying the filling densities of the porous inner filling, different membrane deflections of the actuator were achieved. By linking the actuators, a pneumatic network actuator was developed that could be used in endorobotics. To describe the membrane deflection of an additively manufactured pneumatic actuator, a mathematical model was developed that takes into account the influence of additive manufacturing and porous filling. Using a dedicated test rig, the predicted behavior of the pneumatic actuators was shown to be qualitatively consistent. In addition, a pneumatic network actuator (PneuNet) with a diameter of 17 mm and a height of 76 mm, consisting of nine chambers with different filling densities, could be bent through 82° under a pressure of 8 bar. Our study shows that the variation of filling densities during production leads to different membrane deflections. The mathematical model developed provides satisfactory predictions, although the influence of additive manufacturing needs to be determined experimentally. Post-processing is still a necessary step to realize the full bending potential of these actuators, although challenges regarding air-tightness remain. Future research approaches include studying the deflection behavior of the chambers in multiple directions, investigating alternative materials, and optimizing the printing process to improve mechanical properties and reliability.

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Liu, Junfeng, Yuqian Zhao, Kexian Liu, Linfeng Wang e Fei Li. "Compensation machining of freeform based on fast tool servo system". PLOS ONE 18, n. 3 (16 marzo 2023): e0282752. http://dx.doi.org/10.1371/journal.pone.0282752.

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With the advantages of large field of view, low cost and simple structure, the freeform optical system has extensive requirements in space exploration and other fields. However, the current machining methods for freeform are difficult to meet the requirements of optical use. Based on a developed fast servo tool (FTS) device, this paper proposes an error compensation turning method for freeforms. Firstly, the Zernike polynomial fitting method is used to reconstruct the freeform surface shape error obtained from off-line measurement, and the offset compensation is used to correct the tool path. Then, the compensation processing physical system is built to simulate the off-line compensation processing of the workpiece to verify the feasibility of compensation processing. Finally, the turning compensation processing of convex freeform aluminum mirror is carried out, and the surface accuracy of the workpiece meets the requirements of visible band. The research results have important practical significance for realizing the fast response machining of free-form surface mirror.

5

Horii, T., M. Ishikawa, Soshu Kirihara, Yoshinari Miyamoto e Nobu Yamanaka. "Development of Freeform Fabrication of Metals by Three Diminsional Micro-Welding". Solid State Phenomena 127 (settembre 2007): 189–94. http://dx.doi.org/10.4028/www.scientific.net/ssp.127.189.

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A newly developed freeform fabrication process named 3D Micro-Welding, which is a combined system of a micro-TIG welding and a layered manufacturing method, is demonstrated. Various refractory alloys such as Inconel, stainless steel, and Invar can be freeformed besides elemental metals like titanium. Small metal beads of ~1mm in diameter are formed by emitting micro arc to the top of a thin metal wire of 0.2mm diameter. A fused bead is welded to a metal substrate or previously formed beads. By continuing this process and building up beads layer by layer under the control of CAD/CAM system, 3D objects were produced. In this study, optimization of micro-welding parameters such as the waveform of pulsed arc current and electrode materials were investigated and simple 3D objects of Inconel 600, SUS 304, Invar 42 were formed. The interfaces between adjacent beads were joined well and no crack or pore existed in the formed objects. The density and Vickers hardness of Inconel 600 objects showed comparable values to the commercial Inconel alloy, however the yield strength and Young’s modulus was about 80% and 70% of that alloy, respectively.

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Frank, Samson, Maria Reichenbächer, Michael Seiler, Thomas Arnold e Jens Bliedtner. "Investigation on Subsurface Damage Patterns in Ultrashort Pulse Laser Machining of Glass using Optical Coherence Tomography". EPJ Web of Conferences 287 (2023): 05024. http://dx.doi.org/10.1051/epjconf/202328705024.

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Ultrashort pulse (USP) laser ablation is gaining popularity as a novel manufacturing technique for brittle materials, enabling the creation of complex freeform shapes that are challenging to produce with conventional optics manufacturing techniques. Freeforms have revolutionized optics manufacturing by providing designers with increased degrees of freedom using non-rotational symmetric components. However, this evolution presents new challenges for manufacturing processes, calling for innovative solutions such as USP ablation. To ensure the industrial viability of areal USP laser machining, it is crucial to not only consider material removal rates but also surface quality and subsurface damage (SSD). Especially for optical applications, harsh quality requirements must be met. This study investigates the SSD patterns of fused silica (FS) and borosilicate glass N-BK7 (BK) processed under different laser wavelengths, beam geometries and processing parameters using high-resolution optical coherence tomography (OCT). It is shown that OCT as non-destructive and 3D evaluation method is well-suited for analysing USP processes. The discovered differences in defect morphology between FS and BK emphasize the importance of selecting appropriate processes and process parameters when working with different materials. Compared to previous studies, for the parameter sets analysed here using OCT, much higher defects depths of up to 441 µm were revealed.

7

Zhu, Z., B. Peng, J. Yuan e X. Xu. "Design method of double freeform surface lens with diffuse reflection". Lighting Research & Technology 52, n. 2 (4 febbraio 2019): 247–56. http://dx.doi.org/10.1177/1477153519825875.

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The design method of a double freeform surface lens is being widely applied in non-imaging optical systems. In this paper, a diffuse reflection freeform surface is introduced into the design of a double freeform surface lens. Different from the universal double freeform surface lens, this double freeform surface lens is divided into a small-angle freeform surface and a large-angle diffuse reflection freeform surface. The small-angle freeform surface firstly limits and forms the lighting area. Then, the large-angle freeform surface is designed to improve the efficiency of lighting the area. And this front light diffuse reflection effectively avoids the influence of light source projection onto the lighting effects. Based on this design method, the double freeform surface lens is obtained. The results show that the efficiency of a circular lighting area reaches 81% and the uniformity of the irradiance distribution reaches 91%. And this design is also suitable for forming different shapes of lighting areas while maintaining a better lighting effect.

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Wang, Xuchu, Qingshun Bai, Siyu Gao, Liang Zhao e Kai Cheng. "A Toolpath Planning Method for Optical Freeform Surface Ultra-Precision Turning Based on NURBS Surface Curvature". Machines 11, n. 11 (9 novembre 2023): 1017. http://dx.doi.org/10.3390/machines11111017.

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As the applications for freeform optical surfaces continue to grow, the need for high-precision machining methods is becoming more and more of a necessity. Different toolpath strategies for the ultra-high precision turning of freeform surfaces can have a significant impact on the quality of the machined surfaces. This paper presents a novel toolpath planning method for ultra-precision slow tool servo diamond turning based on the curvature of freeform surfaces. The method analyzes the differential geometric properties of freeform surfaces by reconstructing NURBS freeform surfaces. A mathematical model is constructed based on the parameters of different positions of the freeform surface, toolpath parameters, and tool residual height. Appropriate toolpath parameters can be calculated to generate the optical freeform ultra-precision slow tool servo diamond turning toolpath. Compared with the toolpaths generated by the traditional Archimedes spiral method, the ultra-precision slow tool servo diamond turning toolpath planning method proposed in this paper can generate more uniform toolpaths on the freeform surfaces and keep the residual tool height within a small range.

9

Kong, Lingbao, Yingao Ma, Mingjun Ren, Min Xu e Chifai Cheung. "Generation and characterization of ultra-precision compound freeform surfaces". Science Progress 103, n. 1 (10 ottobre 2019): 003685041988011. http://dx.doi.org/10.1177/0036850419880112.

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Compound freeform surfaces are widely used in bionic and optical applications. The manufacturing and measurement of such surfaces are challenging due to the complex geometry with multi-scale features in a high precision level with sub-micrometer form accuracy and nanometer surface finish. This article presents a study of ultra-precision machining and characterization of compound freeform surfaces. A hybrid machining process by combining slow slide servo and fast tool servo is proposed to machine compound freeform surfaces. The machining process for this hybrid tool servo is explained, and tool path generation is presented. Then, a normal template-based matching and characterization method is proposed to evaluate such compound freeform surfaces. Experimental studies are undertaken to machine a compound freeform surface using the proposed method based on a four-axis ultra-precision machine tool. The machined compound freeform surface is also measured and characterized by the proposed analysis and characterization method. The experimental results are presented, and the machining errors for compound freeform surfaces are also discussed.

10

Li, Hua, Suet To, Ling Bao Kong, Chi Fai Cheung e Wing Bun Lee. "Inspection Technology for F-Theta Lens: Practices and Discussions". Key Engineering Materials 364-366 (dicembre 2007): 1191–96. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.1191.

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This paper presents the inspection technology for a freeform surface component which is named F-theta lens. F-theta lens is widely used in laser scanners, printers, etc. Freeform characterization is one of the main approaches to verify the manufacturing precision of freeform surface. At present, there is still a lack of techniques for the characterization of freeform surfaces. This study aimed to explore some approaches to inspect freeform surfaces. Two types of measurement methods, namely contact and non-contact measurement methods, are employed to measure the F-theta lens surface. The pros and cons, the existing problems, different applications and areas for improvement of the two methods are discussed. A series of advanced measuring instruments are used in the measurement process. A brief description of measurement mechanisms of these instruments is also presented. As a whole, this paper contributes to the development of the precision measurement technology for optical freeform surfaces.

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Zhang, Yilan, Haodong Shi e Huilin Jiang. "Analysis of polarization characteristics of freeform surface optical system". ITM Web of Conferences 45 (2022): 01053. http://dx.doi.org/10.1051/itmconf/20224501053.

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Freeform surfaces are widely used in off-axis optical systems with large aperture, large field of view, and long focal length. The polarization effect caused by the non-rotationally symmetrical shape has an impact on the system’s polarization imaging quality and measurement accuracy. Based on Jones’ notation, this paper proposes a polarization aberration analysis method for fringed Zernike polynomial freeform optical systems and constructs a full-field polarisation aberration analysis model of non-rotationally symmetric freeform reflective optical systems. The light propagation vector k is added on the basis of the two-dimensional ray tracing algorithm. By tracing the full-field polarized light of the off-axis optical system in the field of view, the Jones pupil diagram is obtained. The phase aberration, diattenuation and retardance are separated by Pauli decomposition and SVD decomposition. The off-axis freeform surface optical system is designed. The analysis results show that the phase aberration of the off-axis freeform surface optical system is directly related to the surface shape of the freeform surface. The changes of the freeform surface to the diattenuation and retardance are both 56% of the diattenuation and retardance of the sistem. For deep-space telescopes and lithography systems, it is of great significance for improving system accuracy to master this change.

12

Hu, Zhang Fang, Jian Wei Mao e Yuan Luo. "Research on LED Lighting Secondary Light Distribution by Using a Freeform Lens". Applied Mechanics and Materials 103 (settembre 2011): 138–41. http://dx.doi.org/10.4028/www.scientific.net/amm.103.138.

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Application of semiconductor lighting is widespread, so its secondary light distribution design of the LED for lighting plays an important role. For LED road lighting applications, its uniformity of illumination need to meet certain requirements, a freeform surface using freeform optical lens was designed, in the secondary light distribution. Because of the application of freeform lens, LED lighting illumination uniformity has been improved. Lighting simulation and analysis, results indicate that based on freeform lens, LED lighting has good illumination uniformity, and has well research, development and application prospects.

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Liu, Xinyu, e Jun Zhu. "Design Method of Freeform Off-Axis Multi-Mirror Optical Systems". Photonics 9, n. 8 (30 luglio 2022): 534. http://dx.doi.org/10.3390/photonics9080534.

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A data point calculation method that does not require the use of Fermat′s principle and a simple and general design method of starting points of freeform off-axis multi-mirror optical systems are proposed in this paper, which aim to promote the realization of high-performance reflective systems containing freeform surfaces. Taking a planar system and the required parameters as the input, a good starting point for a freeform off-axis multi-mirror system can be automatically obtained using the proposed method. The design of a freeform off-axis five-mirror system with a low F-number is taken as an example to show the effectiveness of the proposed method. The method can also be used for the design of freeform reflective systems with other numbers of mirrors.

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Luo, D., P. Ge, D. Liu e H. Wang. "A combined lens design for an LED low-beam motorcycle headlight". Lighting Research & Technology 50, n. 3 (6 marzo 2017): 456–66. http://dx.doi.org/10.1177/1477153517697370.

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A conventional low-beam projector headlight design for a motorcycle conventionally uses a combination of an elliptical reflector and a baffle plate. A clear cut-off line is formed by the baffle plate. Since only one freeform surface is used, the dispersion phenomena will occur with a white LED light source because the blue and yellow light is mixed unevenly. This leads to a high colour temperature. Another method uses a micro-lens array to solve the colour temperature problems. Without using the baffle plate, it is difficult to form a clear cut-off line. What’s more, the freeform surface of the lens is complex and difficult to fabricate. We propose a combined lens, which uses a double freeform surface lens combined with a single freeform surface lens. In the combined lens, the double freeform surface lens is designed to solve the colour temperature drift and the single freeform surface lens is designed to solve the problem of the cut-off line. The simulation results can meet the ECE Regulation R113 revision 2(Class B) of the motorcycle low-beam.

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Burada, Dali Ramu, Kamal K. Pant, Vinod Mishra, Mohamed Bichra, Gufran Sayeed Khan, Stefan Sinzinger e Chandra Shakher. "Development of a metrology technique suitable for in situ measurement and corrective manufacturing of freeform optics". Advanced Optical Technologies 8, n. 3-4 (26 giugno 2019): 203–15. http://dx.doi.org/10.1515/aot-2018-0072.

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Abstract The applications of freeform optical surfaces in modern optical systems are providing unique solutions over rotationally symmetric surfaces. These surfaces offer higher degrees of freedom to the designer to enhance the high-end performance of the optical system. The precise metrology of freeform optics is one of the major bottlenecks for its use in imaging applications. Modern optical fabrication methods (i.e. fast or slow tool servo configuration) are, in principle, capable to meet the challenges to generate complex freeform surfaces if supported by precise metrology feedback for error compensation. In the present work, we have developed a Shack-Hartmann sensor-based metrology technique that can be used for quantitative in situ measurement of freeform optics. The sensor head is used to measure freeform optics in the reflection mode by following the CNC tool path in the offline mode. The measurements are used as feedback for corrective machining. Quantitative analysis is also performed to estimate the error budget of the metrology system. Further, the proposed in situ metrology scheme is validated by measuring freeform surface using a coherence correlation interferometric optical profiler.

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Sieber, Ingo, Allen Yi e Ulrich Gengenbach. "Metrology Data-Based Simulation of Freeform Optics". Applied Sciences 8, n. 12 (22 novembre 2018): 2338. http://dx.doi.org/10.3390/app8122338.

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This paper describes the approach to use measurement data to enhance the simulation model for designing freeform optics. Design for manufacturing of freeform optics is still challenging, since the classical tolerancing procedures cannot be applied. In the case of spherical optics manufacturing, tolerances are more or less isotropic, and this relationship is lost in case of freeform surfaces. Hence, an accurate performance prediction of the manufactured optics cannot be made. To make the modeling approach as accurate as possible, integration of measured surface data of fabricated freeform optics in the modeling environment is proposed. This approach enables performance prediction of the real manufactured freeform surfaces as well as optimization of the manufacturing process. In our case study this approach is used on the design of an Alvarez-optics manufactured using a microinjection molding (µIM) process. The parameters of the µIM process are optimized on the basis of simulation analysis resulting in optics, with a performance very close to the nominal design. Measurement of the freeform surfaces is conducted using a tactile surface measurement tool.

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Wang, Su Juan, Su Et To, Xin Chen e Jian Qun Liu. "Development of Cutting Strategy in Ultra-Precision Raster Milling of Freeform Surface". Applied Mechanics and Materials 633-634 (settembre 2014): 615–19. http://dx.doi.org/10.4028/www.scientific.net/amm.633-634.615.

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This paper studies the development of cutting strategy in the fabrication of freeform surface in ultra-precision raster milling (UPRM). The tasks of developing cutting strategy in freeform machining involve in the selection of cutting parameters and the planning of tool paths. An integrated system is built in this study to develop the cutting strategy, automatically generate NC program, simulate the tool paths and machining process, as well as make predictions for the machining time and the surface quality of the raster milled freeform surface. Experiment is conducted to verify the developed system and the experimental results show that the system is applicable for the machining of freeform surface in UPRM. This study therefore contributes to avoiding the need to conduct expensive and time consuming trial cutting tests to ensure the product quality in the freeform machining.

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Lee, Dongyoun, e Junho Hong. "Development of an Adaptive Slicing Algorithm of Laminated Object Manufacturing Based 3D Printing for Freeform Formwork". Buildings 12, n. 9 (30 agosto 2022): 1335. http://dx.doi.org/10.3390/buildings12091335.

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Recently, as “Freeform buildings” have increased in number, studies on ways to increase productivity in the construction of freeform buildings are increasing. In the case of 3D printing in construction, many studies are being conducted using the material extrusion method; among the 3D printing methods, manufacturing freeform forms using laminated object manufacturing (LOM) can overcome the limitation presented above. However, there is a lack of cases used in LOM construction sites, so it is necessary to increase the productivity of construction work and study the slicing method suitable for construction. Therefore, in this paper, we propose using study criteria and adaptive slicing methods to combine both the shape error and the manufacturing time of freeform construction. A case study was conducted to verify the results of this study; the freeform concrete form manufacturing with the algorithm that proposed this study could save 66.1% of the manufacturing time compared with CNC milling, and it needs 19.8% less manufacturing time than the existing uniform slicing method. This is a result of the production of one freeform form, and it can be expected to have a greater effect if applied to many freeform forms used in construction sites. In addition, the results of this study can be used as a decision-making tool that can determine the shape and manufacturing time of production according to the on-site situation.

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Chen, Xun. "Corrective Abrasive Polishing Processes for Freeform Surface". Key Engineering Materials 404 (gennaio 2009): 103–12. http://dx.doi.org/10.4028/www.scientific.net/kem.404.103.

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Traditionally, abrasive finishing process only focused on producing excellent surface finish on regular form shapes. Ever increasing demands in freeform features in aerospace, energy and medicine applications require abrasive finishing technology not only provides excellent surface finish but also is capable to correct the errors on freeform surfaces. The paper presents current development of corrective polishing technology for freeform surfaces.

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Lee, Hyun, Tae-Sik Jang, Ginam Han, Hae-Won Kim e Hyun-Do Jung. "Freeform 3D printing of vascularized tissues: Challenges and strategies". Journal of Tissue Engineering 12 (gennaio 2021): 204173142110572. http://dx.doi.org/10.1177/20417314211057236.

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In recent years, freeform three-dimensional (3D) printing has led to significant advances in the fabrication of artificial tissues with vascularized structures. This technique utilizes a supporting matrix that holds the extruded printing ink and ensures shape maintenance of the printed 3D constructs within the prescribed spatial precision. Since the printing nozzle can be translated omnidirectionally within the supporting matrix, freeform 3D printing is potentially applicable for the fabrication of complex 3D objects, incorporating curved, and irregular shaped vascular networks. To optimize freeform 3D printing quality and performance, the rheological properties of the printing ink and supporting matrix, and the material matching between them are of paramount importance. In this review, we shall compare conventional 3D printing and freeform 3D printing technologies for the fabrication of vascular constructs, and critically discuss their working principles and their advantages and disadvantages. We also provide the detailed material information of emerging printing inks and supporting matrices in recent freeform 3D printing studies. The accompanying challenges are further discussed, aiming to guide freeform 3D printing by the effective design and selection of the most appropriate materials/processes for the development of full-scale functional vascularized artificial tissues.

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Nagdeve, Leeladhar, V. K. Jain e J. Ramkumar. "Nanofinishing of freeform/sculptured surfaces: state-of-the-art". Manufacturing Review 5 (2018): 6. http://dx.doi.org/10.1051/mfreview/2018005.

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Freeform surfaces are being used in a multiplicity of applications in different kinds of industries related to Bio-medical (Bio-implants), micro channels in micro fluidics, automotives, turbine blades, impellers of artificial heart pumps, automobiles etc. Different parts in these industries need nano-level surface finish as their functional inevitability. It is very difficult and challenging to achieve high level of surface finish, especially on the components having freeform (or sculptured) surfaces, complex shapes, and 3-D features. Surface finish is a significant factor, which affects life and functionality of a product. Many traditional and advanced finishing processes have been developed for finishing of freeform/sculptured surfaces but still it has not been possible to achieve uniform nano level surface finish specially in case of freeform surfaces. To overcome the limitations of the existing nanofinishing processes, researchers are developing new processes for uniform nanofinishing of freeform surfaces. In this article, an attempt has been made to review different nanofinishing processes employed for freeform surfaces useful in different types of applications. In addition, experimental work, theoretical analysis and existing challenges of the finishing processes have been identified to fill the research gap.

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Mishra, Vinod, Dali R. Burada, Vinod Karar, Alakesh Manna, Sunil Jha e Gufran Sayeed Khan. "Investigations on flexible pad polishing for nano-finishing of freeform optics mold". Journal of Micromanufacturing 3, n. 2 (30 settembre 2020): 99–112. http://dx.doi.org/10.1177/2516598420939740.

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The need for freeform surfaces are widely recognized in the optical, aerospace, biomedical, and automotive industries. However, the fabrication of freeform surfaces is very difficult and expensive because of the involvement of advanced, multi-axis, dedicated machining processes. In many applications, the machining surface needs further polishing to reduce the surface roughness. The main aim of this work is to investigate the flexible pad polishing process for the finishing of the freeform surface. To achieve this, a flexible pad polishing setup is developed in two-axis configuration that can be integrated with a diamond turning machine or any other computer numerical control (CNC) machine and capable to polish the conventional rotationally symmetric surfaces as well as freeform surfaces. The polishing parameters for the developed polishing head are optimized for the nano-finishing of the freeform mold surface of Stavax ESR steel. The effectiveness of the current polishing setup is demonstrated by measuring the improvement in surface roughness height and profile. Test results reveal that the improvement on the freeform surface is significant, that is, surface roughness ( Ra) reduces from 220 nm to 25 nm while keeping the profile within the desired tolerance.

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Wang, Su Juan, Chi Fai Cheung, Sandy To e Wing Bun Lee. "Fabrication of Freeform Optics in Ultra-Precision Raster Milling". Key Engineering Materials 339 (maggio 2007): 412–16. http://dx.doi.org/10.4028/www.scientific.net/kem.339.412.

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Recently, the high quality and high productivity in fabrication of freeform optics has been of primary interest in manufacturing industries, such as die and mould manufacturing, aerospace part manufacturing, and so forth. However, the fabrication of freeform optics is currently expensive and vastly complex. Ultra-precision raster milling can produce non-rotational symmetric surfaces with sub-micrometric form accuracy and nanometric surface finish without the need for any subsequent post polishing. While, there is little research work focus on this kind of machining method. This paper presents a framework of a tool path generation system for freeform surface ultra-precision raster milling. This system includes model of freeform optics, tool path generator, interference monitor and an optimization model of machining parameters. The tool path generation system can generate interference free and optimal tool path for machining freeform surfaces. Some simulation results have been presented to illustrate the performance of the system.

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Henkel, Sebastian, Christian Schulze, Samson Frank, Christoph Letsch, Jens Bliedtner, Thomas Arnold, Heike Müller e Edda Rädlein. "Investigations on a novel process chain for manufacturing of freeform surfaces". EPJ Web of Conferences 266 (2022): 03010. http://dx.doi.org/10.1051/epjconf/202226603010.

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Freeform optical surfaces have become increasingly important in recent years, as they can be used to construct optical assemblies with a reduced number of optical surfaces compared to systems without freeform surfaces, and thus optical systems can get more compact and lighter. However, the flexible and efficient production of precise optical freeform surfaces poses a major problem. This manifests itself in insufficient precision of the optics, long delivery times and high prices. It is shown, that ultrasonic grinding processes, combined with an ultra-fine grinding process and subsequent plasma jet polishing, are very well suited for the production of freeform optics and have a high technical and economic potential. Therefore, the aim is to validate an industrially suitable process chain based on this combination, in order to produce freeform optics of high accuracy (shape deviations <100 nm RMS) that can be manufactured in significantly fewer steps than before.

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Jiang, W., Bill Tse, Roy Louie e Frankie Chan. "Diamond Turning Freeform Optics". Key Engineering Materials 364-366 (dicembre 2007): 1–6. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.1.

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Freeform optics fabrication has become one of the hottest topics in optics industry in recent years. Although it still remains a challenge, many have tried different ways of manufacturing it. Some have achieved degrees of success. By means of a Nanotech 350-FG five axis diamond turning machine, we too have successfully produced some prototype freeform optics and lens arrays with Slow Tool Servo and Milling method. The produced freeform optics are mainly for automobile LED headlamps and the lens arrays are for LED illumination. In order to produce the freeform optics, we developed our own DT Slow Tool Servo program which is capable of generating a DT program for diamond turning a universal/general 3D freeform surface. Slow Tool Servo technique and Diamond Milling technique were mainly employed to produce these freeform surfaces. The manufacturing process and machining parameter details will be given in the paper. The two main methods we used will be compared and discussed as well. In measuring the freeform surface, a 3D white light interferometer was used to scan and obtain the surface coordinates. The software made by ourselves enabled us to compare the measure results of the work piece with that of the design drawings. The deviation of our finished forms is within 5 um from that of the nominal. The surface quality Rq is about 10 nm. Measuring equipment and methodology will also be discussed in the paper.

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Li, H. F., Chi Fai Cheung, Ling Bao Kong, Wing Bun Lee e Sandy To. "A Study of Measurement Technology for Ultra-Precision Freeform Surfaces". Key Engineering Materials 339 (maggio 2007): 417–21. http://dx.doi.org/10.4028/www.scientific.net/kem.339.417.

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Ultra-precision freeform surfaces have become widely used in advanced optics manufacture. Although these surfaces can be fabricated by ultra-precision freeform machining technology with sub-micrometer form accuracy and surface finish in nanometer range, our current understanding on the evaluation of surface quality of these surfaces is still far from perfect. In this paper, a study of measurement technology for ultra-precision freeform surfaces is presented.

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Liu, Qi Tong, Jian Ming Zhan e Jian Hua Mao. "Study on Profile-Adaptive Tool System for Small Robots in Large Freeform Surface Polishing". Applied Mechanics and Materials 37-38 (novembre 2010): 1327–31. http://dx.doi.org/10.4028/www.scientific.net/amm.37-38.1327.

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An adaptive tool system of polishing robots for large freeform surface which is installed discoid tool is proposed. To improve processing efficiency, the mechanical of adaptive tool system adjust to curvature changing of large freeform surface is designed. Adaptability of the processing is analyzed and simulated, and kinematic equation of tool system is established. The polishing process of large freeform surfaces with tool system is analyzed.

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Zhang, Shen, Jian Jun Wu e Liang Cai Deng. "Springback Prediction and Compensation for Thick Freeform Surface Parts Forming". Applied Mechanics and Materials 271-272 (dicembre 2012): 498–503. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.498.

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The springback phenomenon of thick freeform surface steel plate forming occurs consequentially after unloading, which reduces the accuracy of the parts manufacturing and the processing efficiency. This paper developed a numerical simulation solution to the springback of thick freeform surface parts forming process using PAM-STAMP 2G at 20°C, 200°C, 400°C, 600°C, 700°C and 800°C, respectively. The maximum springback value of freeform surface parts decreases with increasing temperature, at 600°C, the minimum extreme value, and then the value with increasing temperature continues to rise higher. PAM-STAMP 2G offers a Die Compensation module, which is used to modify the die surface of thick freeform surface steel plate forming focused on springback defects. The approach based on iteratively comparing a target part shape with a numerical simulated part shape following forming and springback can be effective in reducing springback error. With it, the new tooling shapes will ensure the geometric accuracy of the thick freeform surface parts.

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Song, Y., J. S. M. Vergeest e W. F. Bronsvoort. "Fitting and Manipulating Freeform Shapes Using Templates". Journal of Computing and Information Science in Engineering 5, n. 2 (27 dicembre 2004): 86–94. http://dx.doi.org/10.1115/1.1875592.

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Finding effective and efficient tools for complex freeform shape modification continues to be a challenging problem in computer graphics and computer-aided design. Although current approaches give reasonable results, their computation time and complexity often prevent their further development in more complex cases, especially in reusing an existing design. In this paper, for a better control of existing freeform shapes, deformable freeform feature templates are introduced. By the advantage of a small number of intrinsic parameters, a given freeform shape can be quickly approximated by one of the deformable templates. The deformable templates are further developed to track and match complex freeform shapes, resulting in extendable templates. With mappings, the original shape and the approximated template are associated. Thus, further shape manipulations can be conducted effectively using high-level intrinsic shape parameters. Experiments were carried out to verify the proposed algorithms. It is also described how the matching and manipulating techniques can be applied in computer graphics and computer-aided design applications.

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Zhu, Jiang, Keisuke Nomura, Tomohisa Tanaka e Yoshio Saito. "Tool Path Planning Assist System for Freeform Surface Machining". Key Engineering Materials 447-448 (settembre 2010): 321–25. http://dx.doi.org/10.4028/www.scientific.net/kem.447-448.321.

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With the rapid development of CG technology and 3D scanning technology, it is easy to design the freeform surface more complexly, but it also makes it difficult to machine such complex freeform surface rapidly and accurately. In this paper, a tool path planning assist system for freeform surface machining is presented. Differing from general CAM systems, in this developed tool path planning assist system, the tool path is generated based on the features of the CAD model, and focus on the applicability of material removal process. New machining strategies for both rough cutting process and finish cutting process are presented. With the assisting of this developed system, freeform surface could be machined efficiently and accurately.

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Meinzer, Nina. "Freeform fabrication". Nature Physics 18, n. 1 (gennaio 2022): 9. http://dx.doi.org/10.1038/s41567-021-01497-5.

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Prautzsch, Hartmut. "Freeform splines". Computer Aided Geometric Design 14, n. 3 (aprile 1997): 201–6. http://dx.doi.org/10.1016/s0167-8396(96)00029-5.

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Huang, Ya, Ri Hong Zhu, Jun Ma e Hua Shen. "Asphericity and Discrete Phase Calculation for Optical Freeform Surface Test with Computer Generated Holograms". Advanced Materials Research 718-720 (luglio 2013): 1797–803. http://dx.doi.org/10.4028/www.scientific.net/amr.718-720.1797.

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Optical freeform surfaces are complex surfaces with non-rotational symmetry that break through the limitations of conventional optical element, and are widely used in advanced optics application for system configuration simplifying and performance enhancing. Interferometric test with computer generated holograms (CGH) has been widely used in the aspherical surfaces testing for their unique wavefront transformation, as well as the freeform surfaces testing with high precision. As an important parameter, it is different at the definition of asphericity in freeform surfaces manufacture and test. Asphericity for interferometric test which verifies the testing ability of the CGH and determines testing system initial configuration was calculated with minimum maximum angle deviation. Reverse ray tracing could get the optimal solution of CGH local phase at certain location in the CGH design. For the non-rotational symmetry of freeform surfaces, the phase of sample point in CGH surface should be calculated in three-dimensional coordinate system. The calculation method of discrete phase was deduced by ray tracing, as well as the phase distribution on freeform surface were proven by calculating in such way. The results were compared with simulation by optical design software. It shows that the method is right and high accuracy to be used in the CGH design for the freeform surfaces.

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Kong, Ling Bao, Chi Fai Cheung, Wing Bun Lee e Sandy To. "A Framework of an Integrated Platform for Modelling and Measurement of Freeform Surface Generation in Ultra-Precision Raster Milling". Key Engineering Materials 339 (maggio 2007): 422–26. http://dx.doi.org/10.4028/www.scientific.net/kem.339.422.

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This paper presents an integrated platform for modelling and measurement of freeform surface generation in ultra-precision raster milling. It is composed of several components which are optics design component, tool path generator, modelling system, measurement system, evaluation component, compensation component and optimization component, respectively. The research emphasizes on modelling and simulation of freeform surface generation, the prediction of the cutting performance and hence the optimization of cutting strategy in the ultra-precision raster milling of freeform surfaces. A measurement system is also proposed to carry out a fast and efficient measurement plan of freeform surfaces. Non-uniform Rational B-Spline (NURBS) will be employed for the development of the integrated platform which will meet Standard for the Exchange of Product model data (STEP).

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Xiong, Juan, e Li Na Han. "Application of CAD/CAM Technology on the Modeling of Freeform Surface Parts". Applied Mechanics and Materials 121-126 (ottobre 2011): 3160–64. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.3160.

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To improve the design of complex curved parts and the shortage of reading two-dimensional drawings. This paper explicitly discussed modeling the bottom of a bottle by enhanced modeling and rendering techniques of CAD/CAM. Established the bottom with freeform surfaces in UG to solve the problem of design a part with freeform surfaces, and rendered the bottom of the bottle to express the result of three-dimensional stereoscopic of a part with freeform surfaces. Rendering is setting the material and texture for the model, and then adding lights and setting the background, etc to help solving the problem of identifying a part with freeform surfaces. Finally, we got the features of UG, the advancement, applicability of CAD/CAM and the necessity of expanding it.

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Geyl, Roland, François Houbre, Yan Cornil, Thierry Lepine e Yvan Sortais. "Optiques freeforms : défis et perspectives". Photoniques, n. 106 (gennaio 2021): 17–21. http://dx.doi.org/10.1051/photon/202110617.

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Les optiques freeforms sont les optiques de demain. Elles inondent déjà notre quotidien dans de nombreux domaines et répondent à une attente profonde du marché. La révolution des optiques freeforms est en marche, une opportunité pour qui saura concevoir ces objets, les fabriquer, les mesurer et les intégrer.

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Dai, Yi Dan, En Shi Qu, Li Yong Ren, Xin Chao Du e Hai Juan Ju. "The Design of Freeform Surface Fresnel Lens Used for LED Uniform Illumination". Applied Mechanics and Materials 571-572 (giugno 2014): 976–79. http://dx.doi.org/10.4028/www.scientific.net/amm.571-572.976.

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This paper presents a new kind of light emitting diode(LED) secondary light distribution lens which adopts the type of Fresnel lens surface. The research purpose of this paper is to improve the LED heat dissipation efficiency of the secondary light distribution lens and the light efficiency, so as to prolong the service life of the LED. In this paper, we use the numerical method for solving the partial differential equation to establish a freeform surface lens which could produce uniform illumination, then the innovative method of combine the Fresnel lens structure with freeform surface lens was proposed. The design of freeform surface Fresnel lens allows dramatically cut the thickness of the lens (as well as the weight and volume) , it can solve the problem of difficulty in heat dissipation. By comparing the ray tracing simulation results of original freeform surface lens and freeform surface Fresnel lens in optical simulation software, experiments show that the latter not only shows the same degree of illumination uniformity, but also greatly reduced the thickness of the lens.

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Wang, Tsung-Hsien, Olivia Espinosa Trujillo, Wen-Shao Chang e Bailin Deng. "Encoding bamboo’s nature for freeform structure design". International Journal of Architectural Computing 15, n. 2 (giugno 2017): 169–82. http://dx.doi.org/10.1177/1478077117714943.

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Bamboo is a construction material that is renewable, environmentally friendly and widely available. It has long been used in various projects, ranging from temporary, easily assembled and rectilinear structures to complex freeform pavilions. Design with bamboo has never been easy to architects and engineers due to its irregular shape and round section. This prompts the need to develop a new design process that can accommodate those properties that hinder bamboo to be used by designers. In this article, we take a close look at freeform structure design and specifically demonstrate how systematically and algorithmically parametric modelling can be used to tackle bamboo material irregularities and bamboo jointing challenges. A two-stage optimization process is proposed to support a fabricable freeform structure design through encoding material properties and freeform shape optimization. The approach approximates the given freeform shape using a finite set of unique bamboo elements while maintaining the aesthetic design intention. By limiting the number of bamboo elements, it will provide insight to both designers and engineers on the efficiency and cost benefits of producing required structure elements for the final assembly.

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Ji, Shijun, Huijuan Yu e Ji Zhao. "An Improved Method for Generating Cutter Points Based on Required Form Accuracy of the Machining Surface". Mathematical Problems in Engineering 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/940643.

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Recently, freeform surfaces are widely used in optical field. Fabrication of freeform surface optics needs high machining accuracy and high efficiency simultaneously. Using the present ultraprecision manufacturing technologies, the form accuracy of freeform surfaces can reach submicrometric or even nanometer range but at the cost of low efficiency; moreover, the form accuracy cannot be predicted; the number and the position of cutter points cannot be accurately controlled before practical machining. A novel strategy of cutter points distribution is proposed in the paper, which is based on the required accuracy of the freeform surface and the machining efficiency can be improved by eliminating redundant cutter points on the processing trajectory. The new idea is detailed, simulations are conducted, and experiments are done to verify the feasibility of the proposed method in fabricating two sinusoidal ring surfaces.

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Li, Jing Yuan, Ren Ping Xu, Kun Qian Wang e Rui Bo Hu. "The Development and Innovation of Yunnan Clay Handicraft Base on the FreeForm System". Advanced Materials Research 230-232 (maggio 2011): 206–11. http://dx.doi.org/10.4028/www.scientific.net/amr.230-232.206.

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Yunnan Clay handicraft is one of the treasures in Chinese ethnic cultural heritage. It is of great value to inherit and innovate the study. This article first introduces the basic principles and application methods of FreeForm, then takes Tile cat for instance to present the detail designing process using FreeForm, next discusses the how to resolve the peculiarity of developing Yunnan Clay handicraft, such as nationality, artistic quality, personalization of consumer, and last demostrates the great role FreeForm plays in the Yunnan Clay handicraft’s advance.

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Lai, J., X. Li e P. Ge. "Designing double freeform surfaces for point source and extended sources using a construction, iteration and optimization process". Lighting Research & Technology 51, n. 7 (22 ottobre 2018): 1118–27. http://dx.doi.org/10.1177/1477153518807507.

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In this paper, a construction-iteration-optimization method is developed to design a double freeform surface lens for point sources as well as extended sources to achieve uniform illuminance. In the construction process, the initial double freeform surfaces are first calculated by the variable separation method with preset source-target ray mapping to obtain the maximum utilization ratio with Fresnel loss. Then, the double freeform surfaces are fitted into a fourth-order XY polynomial surface considering both the coordinates and surface normals of the data points, which ensures the smoothness of freeform surfaces. To reduce the relative standard deviation of the illuminance distribution, an iteration process is required to reconstruct the two freeform surfaces by turns, and this process can be repeated several times to further decrease the deviation of the rays. The system after the construction-iteration process can be taken as a good starting point for further optimization with optical design software. Although the construction-iteration-optimization process is for a point source at first, with the advantage of multi-parameter representation of freeform surfaces we can further optimize the parameters for an extended source by replacing the point source. Simulation results for illuminance uniformity are demonstrated to verify the effectiveness of this method. The energy utilization ratios are above 86.5% and 82.3% with Fresnel loss, while the relative standard deviations of the illuminance distribution are less than 0.036 and 0.063 for a point source and an extended source, respectively.

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Wei, Yi, Peng Zhai, Xiaoyi Chen e Lei He. "Study on Design and Diamond Turning of Optical Freeform Surface for Progressive Addition Lenses". Mathematical Problems in Engineering 2020 (22 febbraio 2020): 1–9. http://dx.doi.org/10.1155/2020/2850606.

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Optical freeform surface components have attracted much attention due to their high degree of design freedom and small size. However, the design and processing difficulty of such components limit its wide application in optics industry. In recent years, diamond turning has been considered an efficient method for processing optical freeform surfaces, but the research on tool path generation of this processing method is not systematic. Progressive addition lens (PAL) is a typical optical freeform surface and is widely used to correct people’s vision problems. Firstly, this paper introduces a method of designing PAL. Then, an optimized tool path generation method for diamond turning of the optical freeform surface is proposed, the equal angle method is used to select the discrete points, and a tool nose radius compensation method suitable for both slow slide servo (SSS) and fast tool servo (FTS) is adopted. Finally, the turning experiment is carried out with a single point diamond lathe, and a PAL surface with a roughness of 0.087 μm was obtained. The power and astigmatism distributions were measured using a Rotlex freeform verifier to verify the rationality of the optical design.

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Langerak, Thomas R. "Local parameterization of freeform shapes using freeform feature recognition". Computer-Aided Design 42, n. 8 (agosto 2010): 682–92. http://dx.doi.org/10.1016/j.cad.2010.02.004.

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Du, Xu, Jie Huang, Li-Min Zhu e Han Ding. "Third-order chord error estimation for freeform contour in computer-aided manufacturing and computer numerical control systems". Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 233, n. 3 (21 febbraio 2018): 863–74. http://dx.doi.org/10.1177/0954405418757266.

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The chord error employed in computer-aided manufacturing and computer numerical control systems is a crucial index to evaluate the machining accuracy of machined parts. It is usually estimated by the second-order method, that is, the osculating circle method. The second-order estimation only takes the curvature of the curve into account, which will bring about great estimation error when applying to freeform curves. In this article, a third-order method that estimates the chord error using conical helices is proposed. By investigating the geometric properties of the conical helix, it is found that there exists a conical helix that has third-order contact with the freeform curve. With the aid of this conical helix, a third-order model for estimating the chord error of freeform curves is developed. Numerical examples of three freeform curves are provided to verify the effectiveness of the proposed estimation model.

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Elber, Gershon. "Multiresolution Curve Editing With Linear Constraints*". Journal of Computing and Information Science in Engineering 1, n. 4 (1 ottobre 2001): 347–55. http://dx.doi.org/10.1115/1.1430679.

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The use of multiresolution control toward the editing of freeform curves and surfaces has already been recognized as a valuable modeling tool [1–3]. Similarly, in contemporary computer aided geometric design, the use of constraints to precisely prescribe freeform shape is considered an essential capability [4,5]. This paper presents a scheme that combines multiresolution control with linear constraints into one framework, allowing one to perform multiresolution manipulation of nonuniform B-spline curves, while specifying and satisfying various linear constraints on the curves. Positional, tangential, and orthogonality constraints are all linear and can be easily incorporated into a multiresolution freeform curve editing environment, as will be shown. Moreover, we also show that the symmetry as well as the area constraints can be reformulated as linear constraints and similarly incorporated. The presented framework is extendible and we also portray this same framework in the context of freeform surfaces.

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Xiong, Juan, e Lan Feng Sun. "Three-Dimensional Modeling and Analysis for Runner Blades of Turbine". Applied Mechanics and Materials 121-126 (ottobre 2011): 1521–25. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.1521.

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In order to improve the design and the two-dimensional drawing identifying technology of freeform surface for the complicated components, such as turbine runner blades, based on the strong modeling technology of CAD/CAM and the software UG of CAD/CAM, detailed analyses three-dimensional modeling of turbine runner, then explain the design difficulties and three-dimensional effect of freeform surface, in order to resolve part of the design difficulties of freeform surface. Provide the original database for computer auxiliary fabricating and explain the practicability of CAD/CAM by analyses three-dimensional modeling of turbine runner.

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Van, Quy Hoang, e Tuyen Bui Ngoc. "Effect of Feed Rate, Tool-Path and Step over on Geometric Accuracy of Freeform Surfaces when 3 Axis CNC Milling". Applied Mechanics and Materials 889 (marzo 2019): 107–14. http://dx.doi.org/10.4028/www.scientific.net/amm.889.107.

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The use of freeform (sculptured) surfaces in the product design process is accelerating at an exponential rate driven by functional as well as esthetics demands. CAD/CAM software is a must in their design are relatively well-covered, issues still remain when it comes to the actual manufacture of freeform surfaces. The major issues are related to the chosen feed rate, toolpaths and step over that would assure the required surface quality, the minimization of the total machining time, etc. This research presents an experimental study to define the effects of machining’s parameters (including: feed rate; toolpath and step over) for CNC 3-axis ball end milling process. The result shows a model for cutting is formulated and incorporated into the parameters of machining that is compatible with all CAD/CAM systems. This result can be used to choose parameters of optimum including federate, toolpath and step over when machining of other freeform surfaces. Keywords: Freeform surface; tool path; ball end milling

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KIM, JUNG SU, DONG SOO KIM, MIN CHEOL LEE e WON HEE LEE. "A METHOD OF 3D FREEFORM FABRICATION USING A CURING OF PHOTOPOLYMER RESIN". International Journal of Modern Physics B 22, n. 09n11 (30 aprile 2008): 1839–45. http://dx.doi.org/10.1142/s021797920804750x.

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Recently, Study of 3D freeform fabrication method was working in the various applications. For example, in the powder base, it's laminated using a binding method or laser sintering method. However, the demerits of these methods are to take long time for post process and not enough to keep high strength of manufacturing part. The binding method needs the post process and the time for post process needs longer time than a manufacturing time. The sintering method has huge size of system with module of the laser. In this paper, we introduce a method of 3D freeform fabrication using a curing of photopolymer resin. A photopolymer curing method has simply fabrication process and high strength of manufacturing part. So, we are configuration the system with compact type module for the office environment and experiment a UV curing test with photopolymer resin in the 3D freeform fabrication method. In the conclusion, we fabricate the 3D freeform part, which is suitable to the office environment using a photopolymer curing method.

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Ren, Ming Jun, Chi Fai Cheung e Ling Bao Kong. "A Study of Fiducial Aided Precision Positioning of Ultra-Precision Freeform Surfaces". Key Engineering Materials 679 (febbraio 2016): 167–71. http://dx.doi.org/10.4028/www.scientific.net/kem.679.167.

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The fabrication of ultra-precision freeform surfaces possessing non-rotationally symmetric geometry and sub-micrometre form accuracy requires an efficient positioning method for precisely locating the position of the workpiece on the machine with high repeatability during the manufacturing cycle. This paper presents an initial attempt to develop a fiducial aided positioning (FAP) method for precisely locating the freeform workpiece on multi-axis machine tools in order to improve the accuracy and efficiency in the manufacturing of ultra-precision freeform surfaces. The FAP method makes use of fiducials to establish intrinsic surface features of the freeform workpiece which are used to determine the coordinate transformation between the coordinate frame of the workpiece and the machine in the machining process and the measurement process. A preliminary simulation experiment was conducted to verify the technical feasibility of the proposed FAP method. The results show that the FAP method is technically feasible to establish a link between the machining and measurement process so as to improve machining accuracy.

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Ge, Q. J., e M. Sirchia. "Computer Aided Geometric Design of Two-Parameter Freeform Motions". Journal of Mechanical Design 121, n. 4 (1 dicembre 1999): 502–6. http://dx.doi.org/10.1115/1.2829489.

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This paper brings together the notion of analytically defined two-parameter motion in Theoretical Kinematics and the notion of freeform surfaces in Computer Aided Geometric Design (CAGD) to develop methods for computer aided design of two-parameter freeform motions. In particular, a rational Be´zier representation for two-parameter freeform motions is developed. It has been shown that the trajectory surface of such a motion is a tensor-product rational Be´zier surface and that such a kinematically generated surface has a geometric as well as a kinematic control structure. The results have not only theoretical interest in CAGD and kinematics but also applications in CAD/CAM and Robotics.

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