Showing papers in "Journal of Engineering for Industry in 1986"

Effect of Hardness on the Surface Integrity of AISI 4340 Steel

Abstract: The effect of hardness on the residual stress in the machined surface of AISI 4340 steel was studied. Chips produced during the machining also were examined and the surface structure was investigated using optical microscope and scanning transmission microscope. Reflection electron diffraction study revealed the existence of austenite in the white layer of the machined surface together with untempered martensite. The residual stress near the machined surface or hardened steel is a compressive stress, and it changes to tensile stress as the hardness decreases. Chip segmentation was observed when steel with hardness of over Rc 50 was machined.

Extensive Analysis and Development of Straightness Measurement by Sequential-Two-Points Method

Abstract: Analyse detaillee et mise au point d'une methode de mesure de la linearite (Methode sequentielle utilisant deux capteurs)

Formation and Ejection of EDM Debris

Abstract: This paper presents a theoretical and experimental investigation into the debris formation and ejection mechanism. An expression for the size of a debris particle is derived using the drop formation energy and the kinetic energy of the ejected debris particle. The velocity of the ejected particle is obtained from expressions derived on the basis of the analysis of hydrodynamic propagation of shock waves generated due to electrical breakdown in dielectric. The debris particles were collected by machining AISI 1020 steel under various operating conditions. The projected areas were measured by a microscope following the standard procedure of particle size measurement. The particle size has been found to be log normally distributed. The experimental values of debris size compare well with the theoretical estimation indicating the validity of the proposed analysis.

Geometric Representation of Translational Swept Volumes and its Applications

Abstract: This paper presents a method for representing the geometries of translational swept volumes of three-dimensional objects which can be constructed by the union of three types of primitive objects: blocks, cylinders, and spheres. The representation method involves three major steps. First, the swept volume of each primitive object is modeled by a boundary representation. Second, based on ray-casting and scan-rendering methods, the boundary representation is converted into a ray in–out classification, which represents the rays entering and exiting from the primitive swept volume. Third, the ray in–out classifications for various primitive swept volumes are combined to represent the swept volume of an object constructed from the primitive objects. Examples are given to illustrate how swept-volume representations can be useful in the context of off-line NC and robot program verifications.

Optimal Point-to-Point Motion Control of Robots With Redundant Degrees of Freedom

Abstract: Control of a kinematically redundant robot arm requires an optimization procedure to determine the motion of the end effector. The criterion for optimization can be minimum motion time, minimum joint displacement increments or a combined merit function specified according to the requirements of the user. Three different methods may be used to perform the computations and obtain the joint coordinate increments for the point-to-point motion control of the robot. The methods are the ''direct,'' the ''pseudoinverse'' and the ''generalized inverse'' methods. These methods are described in detail in this paper, and results obtained with the three methods are compared on the basis of performing simulated tasks. It is concluded that the generalized inverse method is the most suitable, general method for point-to-point control of robots with more than six degrees-of-freedom.

Measurement of Grinding Temperature Using Infrared Radiation Pyrometer With Optical Fiber

Abstract: The heat pulses produced by cutting grains in a workpiece were measured using an infrared radiation pyrometer connected by means of an optical fiber. The results obtained were compared with those from a thermocouple to investigate the effect of differences in response speed on the output. The I.R.P., using an InAs cell as a detector which has a response time in the order of μs, can detect heat pulses with great accuracy and its signal trace versus time has many sharp peaks. The thermocouple formed by spot welding is inferior in response speed, and less accurate in registering heat pulses.

An Integrated Quality Systems Approach to Quality and Productivity Improvement in Continuous Manufacturing Processes

Abstract: An integrated quality systems methodology is presented as a framework within which the concepts of process control can be used to improve quality and productivity. The process is mathematically described by stochastic time series models which statistically describe how inputs and outputs interact. Several different methods for fault identification, including autocorrelation checks of the model residuals, forecasting prediction intervals, and the cusum chart are compared in terms of relative performance. A helix cable manufacturing process is simulated and analyzed by the methodology and faults are identified and suggestions are made for process improvement. Through the simulation these time series control chart methods are shown to be much more effective than conventional methods such as Shewhart control charts.