JPS6255090B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a film-like packing that can detect pressure.

[Conventional technology]

Conventional gaskets only had the function of being deformable.

Therefore, when tightening an object that is tightened through a gasket using a bolt and nut, it is important to check whether the tightening pressure obtained with a wrench represents the true tightening pressure.
Or, it is sometimes unclear whether this indicates the tightening pressure between the bolt and nut due to poor engagement between the threads and grooves of the bolt and nut. Uneven tightening pressure due to the presence of defective bolts or nuts can lead to problems such as breakage of the object when the object being tightened is easily broken, such as glass. When used as a boundary wall, it caused problems such as fluid leakage.

[Purpose of the invention]

An object of the present invention is to provide a packing that makes it possible to measure the stress applied to the packing itself, and to eliminate the drawbacks of the prior art described above.

[Summary of the invention]

The gist of the present invention is that a film-like packing is made of a polymer piezoelectric element, and that it is possible to control the tightening by measuring the piezoelectricity generated in the conductive parts on both sides of the polymer piezoelectric element film as it is tightened. The pressure can be detected on the gasket.

〔Example〕

Embodiments of the present invention will be described in detail below based on the drawings.

Figures 1, 3, and 4 show the case where object 1 and object 2 are tightened with bolt 6, bolt 6 and object 1.
A polymer piezoelectric element film 3 having electrodes 4, 4' on both sides and an insulating washer 7 are interposed between the electrodes 4, 4', and a lead wire 5 is taken out from the electrodes 4, 4' and guided to a measuring circuit (not shown), and the tightening pressure is measured. This is an example of controlling tightening while measuring.

When the object 1 is easily damaged when subjected to non-uniform external force, such as glass or polymethyl methacrylate, the polymer piezoelectric element film 3 must be interposed between the insulating washer 7 and the object 1. Object 1 subjected to non-uniform external force is likely to be damaged.

On the other hand, as shown in FIG. 1, by interposing the polymer piezoelectric element film 3 and applying the load while measuring it with the polymer piezoelectric element film 3, it is possible to apply a uniform external force to the object 1. prevents damage. Furthermore, the polymer piezoelectric element film 3 can also function as a packing as it is.

As other embodiments, in FIGS. 2, 5, and 6, a polymer piezoelectric film 3 functioning as a gasket is interposed between an object 1 and a glass 2, and bolts 6,
In this example, the nut 6' is tightened, and the lead wire 5 is taken out from the electrodes 4, 4' and led to a measuring circuit (not shown) to control the tightening while measuring the tightening pressure.

As shown in FIG. 5, the polymer piezoelectric element film 3
Since it has an electrode divided into four parts, it is possible to measure the stress distribution of each bolt tightening part and control the tightening.

8 each indicate a tightening bolt hole.

FIG. 7 shows an example of application to a gland packing for a polymerization can, in which a gland packing 7' is interposed between an object 1 and a packing holder 2, and a polymer piezoelectric element film 3 functioning as a packing is interposed thereon.
The bolts 6'', 6'' are tightened, and the lead wires 5 are taken out from the electrodes 4, 4' and led to a measuring circuit (not shown) to control the tightening while measuring the tightening pressure.
9 indicates a shaft.

FIG. 8 shows an example of a circuit configuration diagram for measuring tightening pressure, in which one 4 of the conductive parts 4, 4' on both sides of the polymer piezoelectric element film 3 functioning as a packing is grounded, and the other 4 is grounded. ' is connected to the switch 12, the integrating capacitor 10 and the operational amplifier 11, and the integrated and amplified electricity is connected to the indicator 13 and displayed as the tightening pressure.

The polymer piezoelectric element film used in the present invention is preferably a polymer film or sheet (hereinafter simply referred to as a film) that itself has piezoelectricity due to orientation polarization treatment, from the viewpoint of moldability and flexibility.
Also used is a non-piezoelectric polymer film or sheet (hereinafter simply referred to as film) in which piezoelectric objects such as ceramic ferroelectric materials are dispersed.

Examples of the former include polyvinylidene fluoride resin,
Examples include polyvinyl fluoride resin, polyacrylonitrile resin, polyvinyl chloride resin, and the like. Among these, films obtained by oriented and polarized polyvinylidene fluoride resins are particularly excellent, and composite piezoelectric films prepared by dispersing piezoelectric objects in these piezoelectric films are preferably used. Note that the polyvinylidene fluoride resin refers to a vinylidene fluoride homopolymer, a copolymer containing vinylidene fluoride as a main component, a composition material containing any of these as a main component, and the like.

Although the shape of the polymer piezoelectric element film is arbitrary, the thickness of the film is generally preferably in the range of 1 μm to 200 μm, depending on the application.

The polymer piezoelectric element film 3 is attached to the interface between the objects 1 and 2 to be clamped or to the objects 6 and 6' to be clamped.
It is inserted into at least one of the interfaces to be tightened, such as the interface between the object 1 and 2 (see the attached drawings) and the objects 1 and 2 to be tightened.

The polymer piezoelectric element film 3 is manufactured by a known method, and may or may not have electrodes on the surface of the element. In the case of a polymer piezoelectric film 3 that does not have a conductive part such as a vapor-deposited electrode on its surface, at least most of the interface with the element is in contact with both surfaces of the polymer piezoelectric film 3. must be a conductive material.

The piezoelectricity generated in the conductive parts on both sides of the polymer piezoelectric element film 3 does not need to be amplified at all depending on the stress, but it is amplified if necessary, and after being integrated if necessary, it is displayed by an appropriate known method. be done. Since the polymer piezoelectric element film is a differential type transducer,
As it is, it is not possible to sustainably hold a charge against static clamping pressure, so an integral circuit is used to convert the output from the differential converter into an electrical signal corresponding to the clamping pressure. Tightening pressure can be easily specified.

Further, the tightening may be controlled by looking at the momentary tightening stress without using an integral circuit. It is often inconvenient to simply provide a lead wire from the conductive part to the measurement circuit.

For example, if there is a lead wire at the interface between a polymer piezoelectric element film and an object that is in contact with one of its surfaces and is being tightened, if the contact surfaces slide against each other due to tightening, the lead wire will touch the electrode surface provided by vapor deposition. Damage may occur, or tightening of the object may cause leakage of fluid that should originally be shut off. In such cases, it is recommended to provide a groove for taking out the lead wire in a part of the interface, make the conductive part larger than the interface and use the part that does not form the interface as the lead wire exit, or create a part that does not move even when tightened. Efforts are taken to make at least the surface conductive and connect lead wires and conductive parts.
Further, when an object in contact with the polymer piezoelectric element film 3 moves due to tightening, it is desirable that an electrode protector be laminated or covered so as not to damage the electrode surface.

〔Effect of the invention〕

The pressure sensitive gasket of the present invention can be tightened while displaying the tightening pressure. Therefore, even when an object that comes into direct contact with the packing is easily damaged, the damage can be significantly reduced compared to the conventional method. In addition, if it is a conventional gasket, whether true tightening pressure is applied to the gasket, or whether there is a defective bolt or
It was not clear whether the true tightening pressure was not being applied to the packing by the nut, but with the pressure-detectable packing of the present invention, the tightening pressure applied to the packing can be displayed, so problems caused by the above-mentioned unclearness can occur. It has become possible to prevent this from happening. For example, television cathode ray tubes, spy glasses,
The packing of the present invention is particularly preferably used for controlling the tightening of glass or ceramics and other objects used under pressure such as pressure-resistant glass or under reduced pressure, and for manufacturing small precision equipment, high-pressure equipment, vacuum equipment, etc. .

[Brief explanation of the drawing]

1, 2, and 7 are cross-sectional views of examples of tightening control using the pressure-sensable packing of the present invention, and FIGS. It is a top view of a piezoelectric element film, and the fourth
Figure 6 is A- of Figure 3 and Figure 5, respectively.
It is an A' sectional view. FIG. 8 is an example of a circuit configuration for controlling tightening. 1, 2... Object to be tightened, 3... Polymer piezoelectric element film, 4, 4'... Electrode, 5... Lead wire,
6, 6', 6''...Object to be tightened, 7... Washer,
10... Integrating capacitor, 11... Arithmetic amplifier, 1
2...Switch, 13...Indicator.

Claims (1)

[Scope of Claims] 1. Consisting of a polymer piezoelectric element film with a film thickness of 1 μm to 2000 μm, it has a shape that functions as a seal between fastening members and derives piezoelectricity generated on both sides of the polymer piezoelectric element film. It has a conductive part structure, and measures the piezoelectricity derived from the conductive part on both sides of the polymer piezoelectric element film as it is tightened,
Pressure-sensable seal that allows you to control tightening. 2. The pressure-sensable gasket according to claim 1, wherein the conductive portion comprises an electrode divided into a plurality of parts and adhered to the surface of a polymer piezoelectric element film.