JPH0438250Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a thickness measuring device for online measuring the thickness of a sheet material such as paper.

<Prior Art> Conventionally, an upper detection head floating above a sheet material with a certain gap by air blowing and a lower detection head contacting the lower side of the sheet material are connected to the sheet material. Place the substance between them,
A device is known that measures the thickness of a sheet material from the distance between the upper detection head and the lower detection head, which varies depending on the thickness of the sheet material.

FIG. 5 shows a cross section of such a conventional device. In the figure, A is an upper detection head, and a tank cap 2 is attached to a base 1, and a diaphragm 5 is fixed to the periphery of an opening 3 provided in the base 1 via a retainer ring 4.

A conductive target 6 is attached to the center of the diaphragm, and has a chamber 6a inside and a plurality of air blowing holes 6b on its surface. 7 is a tube that guides air to the target 6.

Reference numeral 8 denotes a coil spring fixed to the diaphragm 5 on the opposite side of the target 6, and the other end of this spring is fixed to a support part provided on the base 1 inside the tank cap 2.

B is the lower detection head with body 10 attached to base 9.
is attached to the opening 11 provided in the base 9.
A diaphragm 12 is attached to the periphery of the diaphragm, and a sensor coil 13 is attached to the central opening of this diaphragm.

C is a sheet material sandwiched between these detection heads, and is fed in the _d1 direction.

To measure the thickness, increase the internal pressure of the tank cap 2 and body 10, and
Bring the coil 13 close to the sheet material C.

At this time, air is supplied to the target 6 through the tube 7, and the target's own weight, the restoring force of the coil spring 8, the pressing force of the diaphragm 5, and the levitation force due to air blowing are balanced and the target 6 is shaped into a sheet. Target 6 is balanced from material C by a certain amount (0.1 mm) from sheet material C.
degree) to float. A high frequency radio wave is flowing through the sensor coil 13 in the lower detection head B, and a magnetic flux is generated. The target 6 placed opposite the sensor coil 13 is a good conductor, and the eddy current generated in this portion reduces the magnetic flux of the sensor coil 13 and changes the coil impedance.
This change corresponds to the distance between the target 6 and the sensor coil 13, and since this distance is expressed as the sum of the thickness of the sheet material C and the constant flying height, the change in impedance is detected by a bridge circuit or the like. Then, the thickness of the sheet material C can be measured.

However, in such a device, measurement errors occur unless the flying height of the target 6 is kept constant; however, the flying height fluctuates under the influence of the sheet material C, causing measurement errors. Further, if there is a foreign object in the sheet material C that exceeds the gap between the target 6 and the sheet material C, this foreign material collides with the front end of the target 6, and the foreign object is separated from the sheet material C and becomes a sheet. There have been accidents where holes have been made in the sheet and the sheet has been torn.

Contact measuring devices disclosed in Japanese Patent Application Laid-open No. 53-134467 and Japanese Utility Model Application No. 58-60208 are effective methods for avoiding such drawbacks.

FIG. 6 shows the main parts of the conventional device.

In the figure, A' is the upper detection head, B' is the lower detection head, and C' is the sheet-like material fed in the direction of arrow _d2 . The upper sensing head A' has a base plate 14, a support plate 15 hinged to this base plate, a bellows 16 mounted on the base plate 14 perpendicular to the sheet material C', and a forwardly inclined The support plate 15 and the bellows 1
6 and a target 17 connected to the target 6. The lower detection head B' has the same structure,
It is composed of a base plate 14', a support plate 15', a bellows 16', and a target 17'. In addition, the thickness detection means is
For example, it is provided in the targets 17, 17'.

According to such a configuration, the targets 17,1
7' is in contact with the sheet-like material C', and is not affected by the sheet-like material C' during measurement, and the whole can move in the direction perpendicular to the sheet-like material C'. Since the sheet material C' has an inclined surface, even if there is a foreign object in the sheet material C', it can be overcome, thereby preventing breakage accidents.

However, in the case of such a conventional device, the bellows 16 is attached around the target 17, and when the target 17 goes over a foreign object, the front part does not lift up momentarily and there is a risk of a breakage accident. Of course, it is also possible to reduce the thickness of the bellows 16 in order to make instantaneous movement.
Rubber is usually used for the bellows 16, and from the viewpoint of durability, the bellows cannot be made too thin. Therefore, in the conventional apparatus, the movement of the target 17 was not sufficient and it was not possible to completely prevent the accidental breakage of the sheet-like material.

<Problem to be solved by the invention> The technical problem to be solved by the invention is to develop a contact-type sheet-like thickness measuring device in which the target can follow instantaneous movements and prevent breakage accidents caused by foreign objects. It's about doing.

<Means for solving the problem> The configuration of the present invention is such that a pair of detection heads are brought into contact with a sheet material fed in one direction from above and below, and the detection heads provided on these detection heads are In the apparatus for measuring the thickness of the sheet material, the upper detection head is connected to a target having an inclined surface at the front and a flat surface contacting the sheet material at the rear, and a center of the target. a pressing means for pressing the sheet-like material in a state in which the target contacts the sheet-like material in a microscopic area at a portion thereof and is movable in a direction perpendicular to the sheet-like material; The front end is rotatably supported on a rotating shaft provided in the section and perpendicular to the feeding direction of the sheet-like material, and the rear end is perpendicular to the feeding direction of the sheet-like material provided in the front part of the target. The link is rotatably supported on a rotating shaft and has degrees of freedom at two points.

<Operation> The above technical means operates as follows. That is,
In a steady state, the target is pressed at its center by a pressing means having a minute area, and moves parallel to the surface of the sheet-like material. When a foreign object hits the front part of the target, the target rotates around the contact point between the pressing means and the target, and the front part of the target instantly rides on the foreign object. The entire target is pressed against the sheet of material so that it can move in a direction perpendicular to the sheet material, and once the front part of the target rides on the foreign object, it can pass over the object.

<Examples> Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part of an apparatus according to an embodiment of the present invention, and FIG. 2 is a plan view of a main part of an apparatus according to an embodiment of the present invention. In the figure, the same elements as those in FIGS. 5 and 6 are denoted by the same reference numerals, and explanations thereof will be omitted.
18 is a conductive target placed on the upper side of the sheet-like material C, and an inclined surface 18a is formed in the front part.
A flat surface 18b is provided in the portion that contacts the sheet material C.
is formed. Reference numeral 19 denotes a pressing means for pressing the target 18, which includes a bellows 19a arranged in an air chamber 21 provided on the substrate 20 of the upper detection head A, one end of which is attached to the bellows, and the other end of which presses the center of the target 18. It is composed of a slide shaft 19a that presses against a small area.

22 has its front end rotatably supported on a rotation shaft 22a provided at the front of the substrate 20 of the upper detection slide A and perpendicular to the feeding direction of the sheet material C, and its rear end is attached to the front of the target 18. It is a link that is rotatably supported by a rotary shaft 22b that is perpendicular to the feeding direction of the sheet-like material C and has degrees of freedom at two points.

Note that the bearing portion of the slide shaft 19a is clogged with paper powder etc. from the sheet material C, and the slide shaft 19b
It may make the movement worse. In such a case, an air purge mechanism as shown in FIG. 3 is used.
In this figure, 19c is a slide surface into which the slide shaft 19b is fitted. Reference numeral 19d denotes a sealing plate made of, for example, rubber, and is fixed to the base plate 20 by a presser metal fitting 19e so as to close the opening of a portion with a larger diameter that is connected to the sliding surface 19c. 19f
is a passage through which air to be purged is guided.

With this configuration, the air supplied from the passage 19f is discharged in the direction of the arrow, thereby preventing paper dust from the sheet material C shown by E from clogging the bearing portion of the slide shaft 19b.

In the operating state of the device according to the embodiment of the present invention, the air chamber 21
Air is guided to contract the bellows 19a, and the center of the target 18 is pressed by the tip of the slide shaft 19a. The strength of the pressure depends on the target 1.
The strength is such that the entire target 18 can be lifted up freely when the target 8 lands on a foreign object.

The tip of the slide shaft 19b is in contact with the center of the target 18 over a small area, and the front part of the target 18 is connected to the link 22 so that it can be lifted freely, as shown in FIG. When the foreign object 23 hits the target 18, the front part of the target instantly rides on the foreign object 23. The entire target 18 is pressed so that it can move perpendicularly to the sheet-like material C, and once the front part of the target rides on the foreign object 23, the sheet-like material C can be passed over the foreign object, and the sheet-like material C can be moved. It won't break.

<Effects of the Invention> According to the present invention, in the above-mentioned contact type sheet-like thickness measuring device, the target can follow instantaneous movements, and breakage accidents caused by foreign objects can be prevented.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the main parts of the device according to the present invention;
3 is a sectional view showing a specific example of the bearing portion of the slide shaft in the device according to the present invention, FIG. 4 is an explanatory diagram of the operation of the device according to the present invention, Figure 5 is a sectional view of the conventional device, Figure 6
The figure is a side view of main parts of another conventional device. A, B...detection head, C...sheet-like material,
18...Target, 18a...Slope, 18b
... Flat surface, 19 ... Pressing means, 19a ... Bellows, 19b ... Slide shaft, 22 ... Link.

Claims (1)

[Scope of utility model registration request] In an apparatus for measuring the thickness of a sheet-like material by bringing a pair of detection heads into contact with a sheet-like material fed in one direction from above and below, and using detection means provided on these detection heads, The upper detection head is brought into contact with a target having an inclined surface at the front and a flat surface at the rear that contacts the sheet-like material in a small area at the center of the target, so that the target contacts the sheet-like material. a pressing means that presses against the sheet-like material in a vertically movable state; and a pressing means that is perpendicular to the feeding direction of the sheet-like material, provided on the front part of the substrate facing the sheet-like material of the upper detection head. degrees of freedom at two points: the front end is rotatably supported on a rotating shaft, and the rear end is rotatably supported on a rotating shaft provided at the front of the target and perpendicular to the feeding direction of the sheet material. In a steady state, the target is moved parallel to the surface of the sheet-like material, and when a foreign object hits the front part of the target, the pressing means and the target are moved. 1. An apparatus for measuring the thickness of a sheet-like material, characterized in that the target is rotated around a contact point of the target to cause the front part of the target to ride on the foreign object.