JPH11118464A - Thickness measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a precise non-contact thickness measurement free from error by arranging reference horizontal objects on both upper and lower sides of a sheet like matter, and arranging a range finder and a non-contact range finger between the sheet like matter and the reference horizontal objects. SOLUTION: Reference horizontal objects 4A, 4B are arranged above and under a sheet like matter 1 to be measured. Range finders 5A, 5B are firmly fixed to non-contact range finders 3A, 3B, and arranged between the sheet 1 and the reference horizontal objects 4A, 4B. The reference horizontal, objects 4A, 4B are formed of liquids put in vessels, and the levels opposed to the range fingers 5A, 5B are horizontal face and mutually parallel flat face. The range finder 5A and the non-contact range finder 3A, and the range finder 5B and the non-contact range finder 3B are self-traveled on guide rails 6A, 6B, respectively, and the self-traveling speeds and self-traveling distances of the two sets are mutually synchronized. By use of the measured values by the range finders 5A, 5B in the part of a reference calibration body 2 having a known thickness, the precise measured value of the sheet like matter in an optional position is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the thickness of a sheet without contact.

[0002]

2. Description of the Related Art In the non-contact thickness measurement of running paper sheets, vinyl sheets, metal foils, etc., for example, infrared rays, beta rays, X rays, etc. are irradiated, and the irradiated rays are absorbed by the sheet material to be measured. The amount of the amount to be measured is measured and converted into a thickness.
That is, the measured value of the absorbed amount is converted into a thickness by using the phenomenon that a thicker one absorbs more irradiation light and a thinner one absorbs less irradiation light.

[0003]

The above-mentioned prior art measures a large or small irradiation dose absorbed by a sheet material to be measured and converts it into a thickness, and directly measures the thickness. Instead, various conversion errors occur.

[0004] One example of the conversion error is that the absorbed amount of the irradiation dose is determined by the thickness of the sheet material due to contamination of the sheet material during the manufacturing process, changes in the ambient temperature of the thickness gauge, changes in the ambient humidity, and the like. Is inaccurate in the conversion factor, and thus the accurate thickness cannot be measured.

An object of the present invention is to provide a method for directly measuring the thickness in a non-contact manner, instead of the indirect absorption method which may inevitably cause an error as described above.

[0006]

In order to achieve the above object, a thickness measuring method according to the present invention comprises the steps of: disposing a reference horizontal object on both upper and lower sides of a sheet to be measured; At least one set of a range finder and a non-contact type range finder is provided between and a reference horizontal object.

[0007]

In FIG. 2, the thickness T of the sheet material 1 is T = C
-AB. Here, C is the distance between the upper non-contact distance meter 3A and the lower non-contact distance meter 3B. A
Is the distance between the upper non-contact distance meter and the upper surface of the sheet, and B is the distance between the lower non-contact distance meter and the lower surface of the sheet.

Here, the distance C is determined, for example, as follows. That is, in FIG. 2, a reference calibrator 2 having a known thickness is disposed outside the sheet-like material 1, the non-contact distance meter 3 is moved to the reference calibrator, and the aforementioned T = CA. −
The relational expression of B is applied.

The thickness T of the reference calibrator is known, while A and B are measured values, so C is determined. This C is assumed to be C = Co.

Here, the non-contact distance meter is moved again onto the sheet-like object to be measured and returned. It is desired to apply the above-mentioned relational expression T = CAB in order to measure the thickness T of the sheet-shaped material, but here, difficulty arises. That is, since the non-contact distance meter is moved on the sheet-like object, C at this position does not become Co.

The reason why C does not become Co is that the movement of the non-contact distance meter causes backlash, weight deflection, thermal expansion, etc. of the supporting bracket or hanging bracket, and therefore C is an undefined value. Thus, only A and B can be measured for T = CAB, but since C is indefinite, T
Is also undefined.

In FIG. 1, reference horizontal objects 4A and 4B are arranged above and below a sheet-like material 1 to be measured. Further, the distance meters 5A and 5B are firmly fixed to the non-contact distance meters 3A and 3B. In this case, since the above-mentioned backlash and weight deflection of the support bracket are measured by measuring the distance from the reference horizontal object by the distance meters 5A and 5B, the above-mentioned C becomes a definite value without being uncertain, and accordingly, T is measured. Will be possible.

Here, the reference horizontal object is required to have a more complete horizontal plane, and as shown in FIG.
Since the surface of 4B is a perfect horizontal plane, it is effective as a reference horizontal object.

The glass surface has a smooth surface and is effective as a reference horizontal object when supported horizontally. In addition, since the weight deflection (deviation from the horizontal) to be supported can be calculated from the calculated value of the mechanical deflection, the glass surface whose deflection is corrected by calculation correction or the like is effective as a reference horizontal object. It is.

Further, if the glass material is quartz glass, deviations from the horizontal such as expansion, deflection and distortion due to temperature changes such as temperature fluctuations are minimized. That is, the thermal expansion coefficient of quartz glass is the smallest among the glass materials.

Further, as shown in FIG. 3, a plurality of sets of distance meters 5A are provided.
A set of non-contact distance meters 3A1 to 3B4 is arranged at an equal pitch (pitch distance = P), and reciprocates over the equal pitch (slide bracket 6A disposed substantially parallel to reference horizontal objects 4A and 4B). , 6B in the direction of arrow ST), the thickness of the same point of the sheet-like material 1 to be measured can be measured by two separate sets of non-contact distance meters. Therefore, mutual calibration of the adjacent non-contact distance meters can be realized, and various errors that can occur can be reduced to zero or minimum by the mutual calibration.

The various errors that can occur here are, besides weight deflection, thermal expansion errors due to, for example, temperature fluctuations of the connection fitting 7A in FIG. 1, and further, thermal expansion errors inherent in the non-contact distance meter itself. And so on.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, reference horizontal objects 4A and 4B are liquids placed in containers, and the surfaces facing the distance meters 5A and 5B are horizontal planes and parallel planes to each other. The distance meter 5A and the non-contact distance meter 3A are fixed to each other, and the guide rail 6A
Run on the top. The distance meter 5B and the non-contact distance meter 3B are fixed to each other, and run on the guide rail 6B by themselves.

This self-running is synchronized vertically. That is, the self-running speed and the self-propelled distance of the set of the distance meter 5A and the non-contact distance meter 3A (the upper set of the sheet-like object to be measured) are the same as the set of the distance meter 5B and the non-contact distance meter 3B (the It is synchronized with the self-propelled speed and self-propelled distance of the lower pair.

In the pair of the distance meter and the non-contact distance meter, the above-mentioned Co value is determined by the reference calibrator 2 having a known thickness (thickness = To). That is, since the thickness of the reference calibrator 2 is known, Co = Ao + Bo + To. Ao and Bo are measured values, and Co is determined.

Next, if the measured values at arbitrary places where the rangefinder is self-propelled are A 'and B', the thickness T 'of the sheet-like object at that place is T' = C'-A '-B'. Here, C ′ is obtained by correcting various fluctuations (deflection, backlash, temperature expansion, etc.) from Co, and C ′ + D ′ + E ′ = Co + Do
+ Eo, C ′ = Co + Do + Eo−D′−E ′
It is. Here, Do and Eo are the measured values of the rangefinders 5A and 5B at the reference calibrator 2 portion, and D 'and E' are the measured values of the rangefinders 5A and 5B at the measured portion of the sheet.

In FIG. 1, the reference horizontal object is a liquid,
Desirably, a non-evaporable viscous liquid such as silicone oil is used practically (to prevent the liquid from decreasing due to evaporation and to prevent the liquid surface from waving due to external vibration). As a distance meter and a non-contact distance meter, a laser displacement meter is typically used.

[0023]

As described above, in the thickness measuring method according to the present invention, since the thickness can be measured directly instead of the thickness conversion by the absorption function of the irradiation radiation, various methods caused by the absorption amount conversion can be obtained. Accurate non-contact thickness measurement without errors is possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention. The reference horizontal object is an example of a liquid.

FIG. 2 illustrates a method for calibrating thickness measurements.

FIG. 3 is a diagram showing another application example of the present invention. It is a figure which arranges two or more sets of a distance meter and a non-contact distance meter at equal pitch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sheet-shaped object 2 ... Reference calibration body 3 ... Non-contact distance meter 4 ... Reference horizontal object 5 ... Distance meter 6 ... Slide fitting 7 ... Connection fitting

Claims (5)

[Claims] An object to be measured, wherein a reference horizontal object is provided on both upper and lower sides of a sheet-like object, and a distance meter and a non-contact type distance meter are provided between the sheet-like object and the reference horizontal object. Characteristic thickness measurement method. 2. The method according to claim 1, wherein the reference horizontal object is a liquid. 3. The thickness measuring method according to claim 1, wherein the reference horizontal object is glass, and deflection caused by suspension and support is corrected. 4. A thickness measuring method according to claim 3, wherein the glass is quartz glass. 5. A non-contact distance meter according to claim 1, wherein a plurality of pairs of the distance meter and the non-contact distance meter are arranged at equal pitches, and reciprocate at equal pitches or more. A thickness measurement method comprising mutually calibrating measured values of the thickness.