A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All
Mohan Kumar, G. C.
- A Digital Design Approach and Implementation for Thermal Error Compensation in Machine Tools by Precision Positioning and Feedback Signal Manipulation
Authors
1 National Institute of Technology, Karnataka, Surathkal, IN
2 Mechanical Dept., National Institute of Technology, Karnataka, Surathkal, IN
3 Central Manufacturing Technology Institute, Bengaluru, IN
Source
Reason-A Technical Journal (Formerly Reason-A Technical Magazine), Vol 12 (2013), Pagination: 87-92Abstract
The proposed paper aims at designing a real time precision positioning control circuitry for a numerical control device used to control a machine tool with encoder type feedback. More particularly it is intended to design a digital compensating circuit for modifying a position control signal to effect a correction for repeatable linear errors such as the dimensional changes in the machine structure due to changes induced into the structure by operating temperature ranges. The error correction is performed by modifying encoder type position feedback signals supplied to the machine tool controller. This provides real time compensation for thermal errors in positioning of computer numerically controlled machine tools, coordinate measuring machines (CMMs), robots, assembly systems, and the like.
The error correction being accomplished by the Error Correction Circuit(ECC), which adds or subtracts a predetermined number of pulses to the pulses coming from a feedback device such as encoder to compensate for over shoot or under shoot of the machine tool respectively.
Keywords
Elongation of Ball Screw, Encoder Feedback Pulses, Pulse Addition and Subtraction, Thermally Induced Errors.Full Text
- Through Focus Signature Analysis for Nano Features
Authors
1 Central Manufacturing Technology Institute, Tumkur Road, Bangalore, IN
2 NITK, Suratkal, Mangalore, IN
Source
Manufacturing Technology Today, Vol 13, No 7 (2014), Pagination: 20-25Abstract
Semiconductor device fabrication process is the most sophisticated and complex manufacturing process. Advances in the manufacturing processes has brought down the feature size of gate to as low as 22 nm. Hence there is a great demand for process control of feature dimension below the resolution limit of visible wavelength microscopy. Lot of research has been focused on increasing the resolution of the metrology tools. We have adopted a novel optical technique that shows nanoscale measurement sensitivity using conventional optical microscopes. Here through-focus images are acquired at different focus positions. These focused and defocused images are used to build an intensity map whose signature reflects the target pattern. This technique is used to identify relative nanoscale change in dimension between two targets by finding the change in the signature of the intensity map.Keywords
Through Focus Imaging, Focus Metric, Through Focus Signature, CD Metrology, Nano Metrology, Diffraction Limit.
- Optimization of Manufacturing Process to Improve Casting Yield
Authors
1 J N N College of Engineering, Shimoga, Karnataka, IN
2 Bapuji Institute of Engg. and Technology, Davangere, Karnataka, IN
Source
Manufacturing Technology Today, Vol 7, No 1 (2008), Pagination: 16-21Abstract
Numerical simulation and animation is widely used and accepted in manufacturing to reduce hardware prototyping and to improve the parts design and manufacturing processes. Using casting simulation and animation systems it is possible to define the temperature fields in the mould and the cast parts quantitatively. Through the temperature field analyses, the thermal induced stresses and plastic displacements occurring in the material during the cooling process can be analyzed. The manufacturing tolerance can be controlled in the development phase and time necessary for product design can be optimized.
ProCAST software is used in the present work to organize around a manager, which calls the four different modules. MeshCAST, PreCAST, DataCAST and ViewCAST. First casting geometry, in the form of CAD model is loaded into MeshCAST, to generate a FEM mesh. Then the calculation is configured in PreCAST, the pre-processor, PreCAST is linked to Thermodynamic Databases for the automatic determination of the material properties form thermodynamic databases. Before the solver ProCAST is launched, a data conditioner named DataCAST is run. Finally, the results are viewed and presented in this paper.