Tool orientation effects on the geometry of 5-axis ball-end milling

5-axis ball-end milling has found application in various industries especially for machining of parts with complex surfaces. Additional two degree of freedoms, namely, lead and tilt angles make it possible to machine complex parts by providing extra flexibility in cutting tool orientation. However, they also complicate the geometry of the process. Knowledge of the process geometry is important for understanding of 5-axis ball-end milling operations. Although there are considerable amount of work done in 3-axis milling, the literature on 5-axis ball-end milling is limited. Some of the terminology used in 3-axis milling is not directly applicable to 5-axis ball end-milling. Hence some new process parameters and coordinate systems are defined to represent a 5-axis ball end-milling process completely. The engagement zone between the cutting tool and the workpiece is more involved due to the effects of lead and tilt angles. In this paper, effects of these angles on the process geometry are explained by presenting CAD models and analytical calculations

Modeling dynamics of parallel milling processes in time-domain

The use of parallel milling processes is increasing in various industries due to several advantages of these machine tools. Parallel milling processes are the processes where more than one milling tool simultaneously cut a workpiece. Due to the increased number of cutting tools, they have the potential for considerable increase in productivity as a result of higher material removal rate (MRR). However, dynamic interactions between milling tools may reduce stability limits. Generally, direct dynamic coupling between two milling tools on such a machine is weak since they are located on different spindles. However, there can be a strong dynamic coupling in case of milling a flexible workpiece. In this case, the vibrations caused by one of the tools may have regenerative effects on the other one. In order to address this problem, a stability model that works in time domain has been developed. The model is capable of simulating cases where two flexible milling tools are cutting a flexible workpiece. Several example cases are simulated with the model and results are presented

Modeling dynamics of parallel turning operations

Parallel turning operations are advantageous in terms of productivity since there are more than one cutting tools in operation. However, the dynamic interaction between these parallel tools may create additional stability problems and the advantage of parallel turning may not be utilized to full extent. For that reason, dynamics and stability of parallel turning processes need to be modeled. In this paper, dynamics of two different parallel turning operations where two turning tools cut a common workpiece are modeled. In the first case, the tools are directly coupled to each other whereas in the other case the coupling occurs through the vibration waves left on the workpiece. For these two cases, stability models in frequency and time domain have been developed. The frequency and time-domain solution results are compared and a reasonable agreement is observed. The predicted stability limits are also compared with experimental results where good agreement is demonstrated

Disconnected Skeleton: Shape at its Absolute Scale

We present a new skeletal representation along with a matching framework to address the deformable shape recognition problem. The disconnectedness arises as a result of excessive regularization that we use to describe a shape at an attainably coarse scale. Our motivation is to rely on the stable properties of the shape instead of inaccurately measured secondary details. The new representation does not suffer from the common instability problems of traditional connected skeletons, and the matching process gives quite successful results on a diverse database of 2D shapes. An important difference of our approach from the conventional use of the skeleton is that we replace the local coordinate frame with a global Euclidean frame supported by additional mechanisms to handle articulations and local boundary deformations. As a result, we can produce descriptions that are sensitive to any combination of changes in scale, position, orientation and articulation, as well as invariant ones.Comment: The work excluding {\S}V and {\S}VI has first appeared in 2005 ICCV: Aslan, C., Tari, S.: An Axis-Based Representation for Recognition. In ICCV(2005) 1339- 1346.; Aslan, C., : Disconnected Skeletons for Shape Recognition. Masters thesis, Department of Computer Engineering, Middle East Technical University, May 200

Birefringent and dichroic behaviour of plasmonic nano-antennas

Birefringence and dichroism of plasmonic nano-antennas are investigated. We demonstrate that birefringent and dichroic behaviour of a cross-dipole nanoantenna is due to a length difference, and a relative plasmonic enhancement of the antenna particles, respectively

Single scale factor for the universe from the creation of radiation and matter till the present

A scheme for incorporating the creation of radiation and matter into the cosmological evolution is introduced so that it becomes possible to merge the times before and after the creation of radiation and matter in a single scale factor in Robertson-Walker metric. This scheme is illustrated through a toy model that has the prospect of constituting a basis for a realistic model.Comment: Minor typos are corrected, an acknowledgment is added, to be published in The European Physical Journal

Manipulating Attributes of Natural Scenes via Hallucination

In this study, we explore building a two-stage framework for enabling users to directly manipulate high-level attributes of a natural scene. The key to our approach is a deep generative network which can hallucinate images of a scene as if they were taken at a different season (e.g. during winter), weather condition (e.g. in a cloudy day) or time of the day (e.g. at sunset). Once the scene is hallucinated with the given attributes, the corresponding look is then transferred to the input image while preserving the semantic details intact, giving a photo-realistic manipulation result. As the proposed framework hallucinates what the scene will look like, it does not require any reference style image as commonly utilized in most of the appearance or style transfer approaches. Moreover, it allows to simultaneously manipulate a given scene according to a diverse set of transient attributes within a single model, eliminating the need of training multiple networks per each translation task. Our comprehensive set of qualitative and quantitative results demonstrate the effectiveness of our approach against the competing methods.Comment: Accepted for publication in ACM Transactions on Graphic