JPH06103232B2 - Pressure sensitive foil - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to measurement of contact pressure and its distribution at the interface between solids and solids, or between solids and fluids, and particularly to high pressure of 50 MPa or more such as plastic working. The present invention relates to a pressure sensitive foil suitable for measurement.

(Prior Art) One metal plate (thickness: 0.5 mm) has a continuous comb-shaped protrusion parallel to the 0.5 mm pitch on one side, and it is interposed between solids and the protrusion when vertical force is applied. Attempts to measure the contact pressure by measuring the contact width have been reported [Shigeo Matsubara, Takashi Yoshimura, Hideaki Kudo, Proceedings of the 24th Joint Symposium on Plastic Working, (1973) p.397-400].

(Problems to be Solved by the Invention) In this conventional method for measuring contact pressure using a metal veneer, since the uneven surface of the metal veneer directly contacts the surface of the object to be measured, the surface of the object to be measured is The effects of surface properties such as roughness and hardness appear directly. Further, since the metal plate has a large thickness, it has a problem that it cannot be measured without preparing another tool capable of accommodating the metal plate, and has not been widely used.

(Means for Solving the Problem) The above problem is that the first thin film having an uneven surface that causes plastic deformation, and the relatively hard second opposed to the uneven surface are used instead of using the metal single plate. It is solved by using a pressure sensitive foil composed of a thin film.

The second thin film is effective if it is smoother than the object to be measured, but it is desirable that it is extremely smooth.

In addition, if a third thin film for lubrication is interposed between the first thin film and the second thin film, it is possible that the measurement result fluctuates due to the effect of friction at the interface between the first thin film and the second thin film. Can be avoided. As the third thin film, an oil film, a polymer film or the like can be used.

Further, the first thin film may be sandwiched by the relatively hard second thin films from both sides, and the third thin film for lubrication may be interposed at each interface. With this configuration, the pressure measurement can be performed with higher accuracy.

This pressure-sensitive foil is 1/5 of the pressure-sensitive element made of a conventional metal plate.
The application range can be greatly expanded by forming the thin film with a thickness equal to or less than that.

(Operation) Since the uneven surface that causes the plastic deformation of the first thin film contacts the object to be measured through the relatively hard second thin film, pressure measurement can be performed without being affected by the surface properties of the object to be measured. It becomes possible to do.

The method of contact pressure measurement is to insert this pressure sensitive foil in advance at the interface between the target object and the object, and load it to a predetermined state,
The pressure sensitive foil is taken out, and the deformed state of the surface irregularities of the first thin film is measured by various measuring instruments. The contact pressure and its distribution are obtained by comparing and measuring the measured value and the calibration curve obtained from the measured value of the deformation state of the pressure sensitive foil under a known contact pressure.

(Effects of the Invention) According to the present invention, it is possible to accurately measure a high pressure of about 50 MPa-500 MPa acting on the interface between solids and solids, and solids and fluids. By using a surface roughness meter or the like, it is possible to easily measure the pressure distribution in a fine portion.

Further, since it is a thin film, it is possible to perform accurate measurement without being greatly affected by bending stress or the like even on the stage portion of the measured object.

As a similar commercially available pressure-sensitive element, there is a pressure-sensitive paper (trade name, prescale) manufactured by Fuji Photo Film Co., Ltd., which applies pressure by releasing the color-forming agent contained in the microcapsules to the outside. Is displayed as the color density, and has a different function from the pressure-sensitive foil of the present invention. In addition, the pressure-sensitive paper can only measure a low pressure of 70 MPa or less.

(Example) FIG. 1 is an example of a cross-sectional view of a pressure-sensitive foil according to the present invention.
In this pressure-sensitive foil, a first thin film 1 having a pressure-sensitive function having an uneven surface that causes plastic deformation is sandwiched between second thin films 2 and 3 which are relatively hard and have high flatness. The second thin films 4 and 5 for lubrication are provided between the two. The pressure-sensitive foil of FIG. 1 is sandwiched between two objects that are in arbitrary contact, a load or pressure is applied, the load is removed for a certain period of time, and then the load is removed. The first thin film 1 having a pressure-sensitive function is taken out by peeling off the second and third parts. The fine surface shape of the pressure-sensitive element is measured with a commercially available stylus-type surface roughness meter, and the degree of collapse of fine irregularities is evaluated by Rmax, the change in the thickness of the first thin film, and other parameters. The magnitude and distribution of the contact pressure can be obtained by comparing the value with the measurement result under the known contact pressure.

FIG. 2 is a graph showing stress-strain curves of the first thin film material having surface irregularities for the work-hardened material and the non-work-hardened material. The solid line corresponds to the non-work hardening material, and the dotted line corresponds to the work hardening material. On the graph, in the case of the work-hardened material, contrary to the work-hardened material, the gradient of the stress-strain curve is small and the development of strain is large with the increase of the load. That is, it can be seen that the unevenness of the surface of the thin film increases as the applied pressure increases, which is effective as the first thin film of the present invention. Further, FIG. 3 shows the structure of the pressure sensitive foil shown in FIG.
3 is a graph showing changes in surface roughness Rmax when crushed using the work-hardened material and the non-work-hardened material shown in FIG. 2 as the thin film of FIG. 2 against the average contact pressure / yield stress. The first thin film used had an initial thickness of 56 μm (Fig. 4A), surface roughness Rmax ₀ 1.4 μm (Fig. 4B), pitch 14
μm (FIG. 4C). Both the surface roughness Rmax decreases almost linearly as the contact pressure increases. Therefore, even if the work hardening characteristics are different, both of the
Although it can be used as a material of the thin film of, the non-work hardening material has a larger amount of crushing against a change in stress than the work hardening material, and therefore has excellent pressure sensitivity. Advantageous to use.

The first thin film having a pressure-sensitive function used in the present invention can be produced with high precision by a known processing method such as pressing or knurling during roll forming, and is suitable as a hard second thin film. Is already on the market with good surface accuracy. If the third thin film for lubrication has adhesiveness and the first pressure-sensitive thin film and the second hard thin film have mild adhesiveness, a three-layer structure as shown in FIG. 1 can be easily created. In addition to being capable of being peeled off, it can be easily peeled off from other layers after use.

FIG. 5 is a sectional view of a pressure-sensitive foil having a closed structure, and has a structure in which a hard second thin film 2 encloses a first thin film 1 having a pressure-sensitive function. When such a pressure-sensitive foil having an airtight structure is used, seawater pressure and the like can be directly measured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view in the thickness direction of a pressure-sensitive foil of the present invention, FIG. 2 is a graph showing the equivalent stress-equivalent plastic strain relationship of a metal material having surface irregularities, FIG. 3 is a graph showing a change in surface roughness Rmax of the first thin film constituting the pressure-sensitive foil of the present invention due to pressurization, and FIG. 4 is an uneven shape and dimension example of the first thin film surface of the present invention. FIG. 5 is a sectional view showing the pressure-sensitive foil of the present invention having an airtight structure. (Explanation of reference numerals) 1 ... first thin film having pressure-sensitive function, 2,3 ... hard second thin film, 4,5 ... third thin film for lubrication.

Claims (3)

[Claims] 1. A pressure-sensitive foil comprising a first thin film having an uneven surface that causes plastic deformation, and a relatively hard second thin film facing the uneven surface. 2. The first thin film has unevenness on only one side, and the relatively hard second thin film is also provided on the side of the first thin film having no uneven surface. The pressure-sensitive foil according to claim (1), characterized in that 3. A third thin film for lubrication is interposed between the first thin film and the second thin film, and the third (1) or (2) claim. ) The pressure-sensitive foil described in the item.