Thermal measuring and testing – Temperature measurement – Combined with diverse art device
Patent
1994-03-02
1997-01-07
Gutierrez, Diego F. F.
Thermal measuring and testing
Temperature measurement
Combined with diverse art device
374183, 73160, 219 6917, 36447404, G01K 114, G01K 1300, G01K 716, B23H 500
Patent
active
055909647
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a wire temperature measuring method for a wire electric discharge machine, and more particularly, to a wire temperature measuring method for measuring the temperature distribution of a wire in a wire electric discharge machine.
BACKGROUND ART
The machining speed of a wire electric discharge machine is greatly affected by wire disconnection. Namely, precise machining cannot be effected under conditions in which the frequency of wire cut is high, and accordingly, a machining operation has to be carried out under conditions (low cutting speed, low discharge current)less severe than such machining conditions.
Generally, wire disconnection is considered to be caused because the wire temperature locally rises and thus the wire strength lowers there, as a result of concentrated electric discharge during the machining operation, and it has been confirmed that after concentrated electric discharge actually occurs at a portion of a wire, the wire is disconnected at that portion. Therefore, efforts have been made to avoid concentrated electric discharge, for example, to control the on-off time of a machining power supply.
The most important factor in the phenomenon of wire disconnection is considered to be the wire temperature and the temperature distribution during a machining operation. Specifically, if the local temperature rise of the wire is moderate during machining operation, then it is necessary that the entire wire be cooled more intensely. Conversely, if the local temperature rise of the wire is extremely high, it is necessary to distribute the electric discharge. In any event, it is at present difficult to directly measure the wire temperature, and effective measures still remain unfound.
A first method currently implemented for measuring the wire temperature is a method in which the wire temperature is estimated based on the temperature-strength characteristic of the wire. When the wire is disconnected under certain conditions, the temperature of the disconnected portion of the wire is estimated from the tension then acting on the wire.
A second method is a method based on analysis, wherein the wire temperature is calculated based on an assumed random heating of the wire along the length thereof and an assumed heat transfer coefficient of a wire surface.
According to the first method, however, only the temperature of the disconnected portion of the wire is estimated, and it is not possible to find the temperature of the entire wire or the temperature distribution.
The second method does not take account of the effect produced by the flow of cooling water in the machining groove, which provides a dominant wire cooling effect. Thus, estimation of the heat transfer coefficient is not as effective as expected, and actual wire temperature cannot be calculated with high accuracy.
DISCLOSURE OF THE INVENTION
The present invention has been made in view of the above circumstances, and an object thereof is to provide a wire temperature measuring method for a wire electric discharge machine by which accurate measurement of wire temperature can be permitted.
Another object of the present invention is to provide a wire temperature measuring method for a wire electric discharge machine by which temperature distribution can be accurately measured.
To achieve the above objects, the present invention provides a method of measuring the temperature of a wire during a machining operation of a wire electric discharge machine, wherein a resistance value of the wire is obtained based on a loop current flowing after cutoff of a discharge voltage, and the temperature of the wire is obtained based on the resistance value.
The present invention also provides a method of measuring the temperature of a wire during a machining operation of a wire electric discharge machine, wherein an electric discharge position is detected based on upper and lower currents flowing, respectively, from upper and lower electrodes during electric discharge, a resistance value between the electric di
REFERENCES:
patent: 4427870 (1984-01-01), Inoue
patent: 4474825 (1984-10-01), Schmidt
patent: 4675491 (1987-06-01), Marendaz
patent: 4801779 (1989-01-01), Obara
patent: 4825030 (1989-04-01), Demellayer
Patent Abstracts of Japan, vol. 16, No. 203, 14 May 1992, (JP-A-04 030 916, published Feb. 3, 1992) Only abstract considered.
Ito Masaya
Kita Yuki
Obara Haruki
Fanuc Ltd
Gutierrez Diego F. F.
LandOfFree
Wire temperature measuring method for a wire electric discharge does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Wire temperature measuring method for a wire electric discharge , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wire temperature measuring method for a wire electric discharge will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1759489