Takaaki Nagao

Development of an intelligent machining center incorporating active compensation for thermal distortion

An intelligent machining center that employs thermal actuators to actively compensate for thermal deformation has been designed, constructed and tested. The machining center also incorporates an intelligent controller, force and deformation sensors and fail-safe mechanism to protect against catastrophic failure of the system. Both matrix control techniques and neural network approaches to the control of the thermal deformation of the machine structure have been tested. In both cases, the measured maximum thermal deformation was controlled to a level of 10 micrometers, approximately 1/3 the level of the uncontrolled machine.

Development of tele-operated micro-handling/machining system based on information transformation

Describes the construction of a tele-operated handling/machining system which operates in the micrometer to millimeter range. The system is equipped with a pair of three dimensional force sensors and can be controlled remotely using a three dimensional joystick. The paper presents a transformation method for converting multi-axis force information to auditory information. Such a transformation conveys a realistic sense of the state of the operation and allows high operability of the system. Experimental results are presented which demonstrate the effectiveness of the implemented system.

Investigation into Drilling Laminated Printed Circuit Board Using a Torque-Thrust-Temperature Sensor

A tool-holder type FM-transmitting torque-thrust-temperature sensor TTT-1 has been newly developed and tested to pursue the optimum condition for drilling of laminated printed circuit board for large scale computers. The torque, thrust and temperature at the drilling point were measured. Consequently it has been found that temperature rises in proportion to the square root of time at the drilling point, and the increased thickness of work raises it and causes smear or breakage of drill. There is the optimum range of drilling condition with respect to the thickness of work, feed, cutting speed, etc.,

Real-Time Machining State Detection Using Multiaxis Force Sensing

Abstract To realize fully-automated, intelligent machining. it is necessary to develop a method for judging the machining state in real-time. A method for determining the machining state in milling is described. The technique utilizes the “force vector locus” determined from the measured force data. The variance in the distance from the center of gravity to each sample point is used to distinguish between normal cutting and chatter conditions. Because the variance depends on the cutting conditions, as well as on the cutting state. the threshold variance is set relative to the ideal variance calculated from the Kronenbers cutting force model. Experiments have demonstrated the utility of the technique in actual milling operations.

A tele-micro machining system with operational environment transmission under a stereo-SEM

This paper describes a tele-micro machining system which works under a stereo SEM and has operational environment transmission capability. The system includes a 3-axis force sensing table, the signal from which is converted into auditory information to enhance the operability of the system. Furthermore, the cutting state in micro-cutting is reflected as force feedback to the master joystick using a newly introduced index which represents the cutting state. Finally, the cutting force in the micro-world is analyzed and compared with that in the macro-world.

Networked Manufacturing with Reality Sensation for Technology Transfer

Abstract This paper describes a networked remote manufacturing system with reality transmission capability for simultaneous technology transfer. The technologies presented in the paper can be used to establish a remote operation and monitoring function as an advanced user interface. The system consists of an open-architecture CNC controller, sensors to monitor the machining state, mechanical fuses to prevent overloads, apparatuses to present visual, auditory, force and tactile information to the user interface, and an input device to operate a machine tool. In the experiment, visual, force, auditory and tactile information were successfully presented to operate the system remotely using multi-axis force information.

Development of a Fail-safe System for NC Machining Centers

24 hour, unmanned operation of CIM systems requires the development of techniques for the highly reliable operation of machine tools. One possible approach is the development of fail-safe devices, which prevent damage to the machine tool when system faults occur. The authors Lave developed a system which has high stiffness under normal cutting conditions but retracts the cutting tool from the cut when a preset threshold force level is exceeded. The system has been did on a full-sized NC machining center and its performance has been measured.

Development of a Force Controlled Automatic Grinding System for Actual NC Machining Centers

Abstract The authors have developed an automatic grinding system which is constructed on actual NC machining center. A ring-shape 6-axis force sensor, a fail safe structure and a compliance device are newly invented for this purpose. By these devices and automatic force control theory, the movement direction of the grinder is automatically decided and the grinding force is maintained constant. In such a way, the cut surface is ground automatically without any information about surface configuration.

Actual Conceptual Design Process for an Intelligent Machining Center

Abstract The conceptual process in design proceeds in the order “Performance → Mechanism → Structure,” and advances through “Application and Evaluation” in what may be thought of as a conceptual development spiral. In actual designs, these spirals are repeated and the process proceeds in the order “Conceptual sketch → Plan drawing → Final plan drawing.” Progress in the conceptual process corresponds to equivalent progress in the detail design operation. “Eight design principles for machines” and “Six design principles for intelligent manufacturing systems” are proposed. By using these principles, a fundamental structure for intelligent manufacturing systems is established and applied to the design of an intelligent machining center that has been built and tested. Testing and evaluation of the machining center that was developed verified the validity and the effectiveness of the proposed concepts.

In-process prediction and prevention of the breakage of small diameter drills based on theoretical analysis

The in-process prediction and prevention of the breakage of small diameter drills has been investigated. A series of drilling tests has been carried out with newly developed torque-thrust sensors. It has been determined that it is possible to predict and prevent drill breakage by monitoring the torque and the thrust, since these force components rise suddenly and exceed threshold values just before the breakage. To determine the appropriate threshold values, the stress due to the torque, the stability of drill motion and the temperature rise at the drill tip have been analyzed theoretically. From these calculations, the maximum shear stress in the drill, the combinations of angular velocity and thrust values which lead to instability and an expression for the temperature rise at the drill tip have been obtained.