JPH07253302A - Thickness measuring apparatus for sheetlike material - Google Patents

Abstract

PURPOSE:To prevent breakage during the measuring of the thickness of a thin sheet by arranging a flow regulating valve between a three-way changeover valve and a tank cap to act as resistor of an flow rate of air in the introduction thereof and as non-resistor in the discharging thereof. CONSTITUTION:A flow regulating valve 30 is so arranged between a three-way solenoid valve 12 and a tank cap 2 to have an air flow choking mechanism E and a one-way passage mechanism F which is adapted to close to the flow of air from one way and pose no resistance to the flow of air from the opposite way. In the measurement of the thickness of a sheetlike matter (paper) C thick relatively (about 40-50mum), the mechanism E is opened fully to accelerate the speed of a conductor target 7 when contacting the paper C, for example, to 0.1sec. By the contrary, in the measurement of the thickness (about 20mum) thin relatively, the mechanism E is throttled to slow the lowering speed of the target 7 to about 0.5sec. by regulating the amount of the air flowing into the cap 2. When the paper C is separated from the target 7, the solenoid valve 12 is turned OFF to make the air in the cap 2 flow out to the discharge side (k) of the valve 12 from the mechanism F.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the thickness of a sheet material on-line, and for preventing the damage to a thin sheet mainly when measuring the thickness of a relatively thick sheet to a relatively thin sheet. The present invention relates to a thickness measuring device for a sheet material.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view of a conventional apparatus having a structure in which air is introduced into a tank cap to bring a target into contact with a sheet (eg, paper). In the figure, A is an upper detection head, in which a tank cap 2 is mounted on a base 1, and a shaft 6 hermetically sealed by a bellows 5 is arranged perpendicularly to a sheet C in the tank cap 2. Has been done. A coil-shaped spring 8 is wound around the shaft 6, and one end (the side in contact with the sheet) penetrates the base 1 and a conductor target 7 is attached.

A predetermined air pressure is introduced into the tank cap 2 from an air source (not shown) through the pressure reducing valve 11 and the three-way solenoid valve 12. Reference numeral 14 is an air-electric converter that detects the air pressure in the tank cap 2 and converts it into an electric signal, and monitors the contact pressure between the target 7 and the seat.

A lower detection head B has a body 21 mounted on a base 20. A diaphragm 23 is attached to the periphery of an opening 22 provided in the base 20, and a sensor and a sensor are provided at the central opening of the diaphragm 23.
A storage container 25 that stores the coil 24 is attached. Numeral 26 is a cylinder which introduces air by an electromagnetic valve 27 and arranges the storage container 25 so as to have a predetermined reference surface via a shaft 28. Reference numeral 29 is a displacement voltage converter for converting the displacement of the sensor coil into a voltage.

With such a structure, when the sheet C is fed in the direction of the arrow D ₁ , the upper detection head A and the lower detection head B follow the guide (not shown) on the frame and the width of the sheet C. It is reciprocally driven in the direction (perpendicular to the paper surface). To measure the thickness, the sheet C is sandwiched between the detection heads A and B, and air is supplied to the tank cap 2 via the three-way solenoid valve 12 to increase the internal pressure.

As a result, the bellows 5 contracts downward against the force of the spring 8 and brings the target 4 fixed to the tip of the shaft 6 closer to the sensor coil 24 via the sheet C.
The storage container 25 to which the sensor coil 24 is fixed is moved upward by the cylinder 26, but is fixed at a predetermined position with respect to the base 20 by a mechanical stopper (not shown), and serves as a reference plane for measuring the thickness of the sheet C. Becomes

Sensor coil 2 in the lower detection head B
A high-frequency current is passed through 4 and a magnetic flux is generated. The target 7 arranged so as to face the sensor coil 24 is a good conductor, and an eddy current is generated in this portion. The eddy current reduces the magnetic flux of the sensor coil 24 and changes the coil impedance. This impedance change is proportional to the distance between the target 7 and the sensor coil 24, and this distance becomes the thickness of the sheet C. Therefore, if the impedance change is detected by a bridge circuit or the like (not shown), the sheet C is detected. Thickness can be measured online.

[0008]

By the way, in the measuring device having the above-described structure, the target 7 is the spring 8 in the non-measuring state.
It is pulled up by and the distance from the sheet C is 5
It is about 6 mm. And, for example, 40 to 50 μ
When measuring a paper thickness of about m, the pressure of the pressure reducing valve 11 is adjusted so that the contact pressure with the target 7 is several tens of g. In that case, when the three-way solenoid valve 12 is opened, the speed until the bellows 5 contracts and the target 7 comes into contact with the paper is about 0.1 seconds.

Next, when trying to measure a thin sheet (for example, a paper of about 20 μm used for making a capacitor) by using the same device, the paper is thin, so that the paper is damaged if the speed of the target in contact with the paper is high. There was a problem. The present invention has been made in view of the drawbacks of the conventional example, and an object thereof is to limit the speed of a target at the time of contact with a sheet, thereby making it possible to reduce the thickness of a thin sheet. An object of the present invention is to provide a device for measuring the thickness of a sheet-like material which is not likely to be damaged.

[0010]

In order to solve the above-mentioned problems, the present invention is directed to a pair of detection heads arranged to face each other with a sheet-like substance interposed therebetween, and a detection head on one side of the pair of detection heads. A sensor coil, a tank cap provided on the other detection head of the pair of detection heads, and a conductor target arranged in the tank cap and driven to the sheet-like substance side by air pressure,
From a pressure reducing valve for introducing air into the tank cap and a three-way switching valve, and a change in the impedance of the sensor coil that changes in relation to the thickness of the sheet when the conductor target comes into contact with the sheet-like substance side. In a device for measuring the thickness of the sheet-like substance, when air is introduced into the tank cap between the three-way switching valve and the tank cap, it serves as a resistor for the air flow rate and removes air from the tank cap. In this case, a flow control valve that is a non-resistor is arranged.

[0011]

When the air is introduced into the tank cap, the flow rate control valve acts as a resistor for the air flow rate, so that the amount of air flowing into the tank cap is limited, and the speed at which the target contacts the paper becomes slow. When the air is removed from the tank cap, the flow rate control valve becomes a non-resistor, so it quickly separates.

[0012]

Embodiments will be described in detail below with reference to the drawings. 1 is an explanatory view of a main part of an embodiment of the present invention. In the figure, the same parts as those in FIG. In the figure, the difference from the conventional example shown in FIG.
The flow control valve 30 is provided between the tank cap 2 and the tank cap 2. The flow rate control valve 30 includes an air flow rate restricting mechanism E,
It has a one-way mechanism F that is closed to the flow from one side and has no air resistance to the flow from the opposite direction.

In the above construction, the paper thickness is relatively thick (4
In the case of 0 to 50 μm), the diaphragm mechanism E is fully opened, and the speed at which the target comes into contact with the paper is kept as usual (for example, 0.1
Seconds). Next relatively thin paper thickness (about 20 μm)
In the case of, the throttle mechanism is throttled to limit the amount of air flowing into the tank cap 2. When the target is removed from the paper, the three-way solenoid valve 12 is turned off, and the air in the tank 2 passes through the one-way mechanism F side and flows out to the discharge side (direction of arrow k) of the three-way solenoid valve 12. As a result of an experiment conducted by the present inventor using a commercially available flow rate control valve, good results were obtained by slowing down the target descending speed to about 0.5 seconds.

[0014]

As described above in detail with reference to the embodiments, according to the present invention, in a device for measuring the thickness of a sheet-like substance, air is stored between the three-way switching valve and the tank cap. Since a flow control valve that functions as a resistor for air flow when introduced into the cap and a non-resistor when removing air from the tank cap, it is possible to limit the descent speed of the target according to the paper thickness. , It is possible to realize a device for measuring the thickness of a sheet-like substance that does not damage the paper at the time of contact.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of essential parts showing an embodiment of a thickness measuring device for a sheet-like substance of the present invention.

FIG. 2 is a cross-sectional configuration diagram of a main part of a conventional device. A Upper detection head B Lower detection head C Sheet material 1,20 Base 2 Tank cap 5 Bellows 6 Shaft 7 Target 11 Pressure reducing valve 12 3-way solenoid valve 24 Sensor coil 25 Storage container 30 Flow control valve

Claims (1)

[Claims] 1. A pair of detection heads arranged to face each other with a sheet-like substance interposed therebetween, a sensor coil provided on the detection head on one side of the pair of detection heads, and a pair of the detection heads. A tank cap provided on the detection head on the other side, a conductor target arranged in the tank cap and driven to the sheet-like substance side by air pressure, a pressure reducing valve for introducing air into the tank cap, and a three-way switching A valve and an apparatus adapted to measure the thickness of the sheet-like material from a change in impedance of the sensor coil, which is brought into contact with the sheet-like material side of the valve and changes in relation to the thickness of the sheet. , Said 3
It is characterized by arranging a flow control valve between the one-way switching valve and the tank cap that functions as an air flow resistance element when air is introduced into the tank cap and a non-resistance element when bleeding air from the tank cap. Sheet thickness measuring device.