Thermal measuring and testing – Thermal testing of a nonthermal quantity – Expansion or contraction characteristics
Patent
1992-02-14
1993-05-11
Yasich, Daniel M.
Thermal measuring and testing
Thermal testing of a nonthermal quantity
Expansion or contraction characteristics
374130, G01N 2516
Patent
active
052095690
DESCRIPTION:
BRIEF SUMMARY
INDUSTRIAL FIELD OF THE INVENTION
This invention relates to an apparatus for the precise and automatic measuring of thermal dimensional change [such as thermal linear expansion coefficient (hereinafter referred to as thermal expansion coefficient) or creep deformation rate] mainly of ceramics and the like under high temperature by using a laser measuring instrument and in non-contact type.
PRIOR ART
The thermal expansion coefficient of fine ceramics, refractories, pottery and porcelain, glass or ceramics of composite materials thereof with metal, or a variety of metals is one of the most important properties, which guides the determination of expansion joint of the lining refractories of furnace used in the hot state. Conventionally there are known, as prior art, Japanese Patent Kokai No. 39,540/85 relating to "Apparatus for Measuring Thermal Expansion Coefficient", Japanese Patent Kokai No. 7,452/86 relating to "Apparatus for Measuring Thermal Dimensional Change of Ceramics or the Like", and Japanese Patent Kokai No. 172,041/86 relating to "Apparatus for Measuring Thermal Dimensional change of Ceramics or the like".
As an example of the known techniques Patent Kokai No. 39,540/85 which is concerned with an apparatus for measuring thermal expansion coefficient is illustrated in FIG. 6. This apparatus is to automatically measure the thermal dimensional change of a specimen by combining two pairs each of a dimensional change measuring apparatus consisting of cameras 22 combined with lens systems 21 each internally housing a solid scanning photo diode elements and consisting of camera control units 23, and of an illumination means 24. The dimensional change of a specimen 8 within a heating furnace 1 is measured in such a way that the specimen is illuminated by the illumination means 24 from the right angular direction to the axis of the specimen, and the dark portion for which light has been shielded by the specimen and the light portion for the light has reached directly are magnifyingly projected on the surface of the solid scanning photo diode elements by the telephoto lens 21 thereby relying on the ratio of the light portion to the dark portion. In such a case the outputs of the two camera control units 23 are added and the output is made by the digital output signal according to the dimensional change.
The output thus produced and the digital output signal of a digital thermometer 13 are input into a computer 15 through an interface 14 when a storage operation is effected, and the relation between the temperature and the thermal expansion coefficient is graphed by a digital plotter 16.
According to this method, however, the measuring range by one camera 22 is only about 3 mm in the case of 1 .mu.m measuring resolution. Further, in case two cameras 22 are used in parallel to increase the measuring precision there is an 80 mm space between the two cameras, so that only specimens having a dimension not smaller than 80 mm can be measured.
These days, as fine ceramics and the like have been developed a measurement for small-size specimens is desired. To meet such requirement specimens having a dimension of not greater than 80 mm are measured either by fixing a prism 25 at the end of each camera 22 as shown in FIG. 7 or by positioning two cameras 22 oppositely as described in Japanese Patent Kokai No. 172,041/86 which relates to "Apparatus for Measuring Thermal Dimensional Change of Ceramics or the Like". However, the resolution of the solid scanning photo diode element camera 22 is limited to 1 .mu.m, and since the expansion rate is small in the case of small-size specimens a resolution in the sub-micron order is required these days.
Further, the measuring range of one camera 22 unit using the solid scanning photo diode element is about 3 mm, so that there arises a problem that it is impossible to measure abnormally expanding specimens or greatly shrinking specimens.
DISCLOSURE OF THE INVENTION
The present invention relates to an apparatus for measuring thermal dimensional change of ceramics or the lik
REFERENCES:
patent: 3930730 (1976-01-01), Laurens et al.
patent: 5121987 (1992-06-01), Berg
Fujiwara Teiichi
Hisanari Toshiaki
Mimura Toshisada
Shinagawa Refractories Co. Ltd.
Yasich Daniel M.
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