JP2013036868A - Jig for distortion gauge installation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a jig for distortion gauge installation that enables a distortion gauge to be easily installed in a mold for fabricating a hardened cement object and, moreover, the installed distortion gauge to accurately measure any distortion of the hardened cement object.SOLUTION: A jig for distortion gauge installation for use in installing a long distortion gauge in a cylindrical mold comprises a cylindrical through part in which a through hole to allow, in a state of being used in the mold, the distortion gauge to penetrate in the cylinder axis direction of the mold, and a plurality of supporting extending parts extending from the through part as far outward as to come into contact with the inner face of the mold to support the through part. The jig is so configured that the center axis of the mold is positioned in the through hole of the through part.

Description

  The present invention relates to a strain gauge installation jig.

  Conventionally, for example, in order to measure the strain of a hardened cement obtained by hydration of cement, a long strain gauge is embedded in the hardened cement and the strain of the hardened cement is measured by the strain gauge. It has been broken. By performing such measurement, it is possible to grasp the shrinkage characteristics of the hardened cement body over time.

  Specifically, as a method for measuring the strain of the hardened cement body, for example, a strain gauge is installed along the central axis of the cylindrical mold, and then the hardened cement body is produced in the mold. Thus, it is known that the shrinkage with time of a hardened cement body in which a strain gauge is embedded is measured by the strain gauge (Patent Documents 1 and 2). When the strain gauge is installed along the central axis of the cylindrical formwork, the strain gauge is embedded along the central axis of the hardened cement body, and the force generated by the strain of the hardened cement body Since the strain gauge is applied more evenly, strain measurement can be performed with relatively high accuracy.

JP2007-057493A JP 2001-324302 A

However, in the method described in the above-mentioned patent document, the lead wire attached to the strain gauge is fixed to a mold frame or the like, and the strain gauge is suspended from the fixed lead wire to be installed at a predetermined position in the mold frame. It is necessary. Therefore, there is a problem that it is relatively difficult to install a strain gauge at a predetermined position in the mold. In addition, there is a problem in that the accuracy of measurement is not always sufficient because the strain gauge is difficult to install and the strain gauge cannot always be arranged accurately along the central axis of the mold.
Therefore, a strain gauge for measuring strain on hardened cement can be easily installed in the mold, and the strain gauge installation treatment can accurately measure strain on hardened cement using the installed strain gauge. Tools are required.

  In view of the above-mentioned problems and demands, the present invention is a strain gauge installation for which a strain gauge can be easily installed in a cylindrical formwork and strain measurement can be performed with sufficient accuracy by the installed strain gauge. It is an object to provide a jig.

In order to solve the above problems, a strain gauge installation jig according to the present invention is a strain gauge installation jig used for installing a long strain gauge in a cylindrical mold,
In a state of use in the mold, a cylindrical through part in which a through hole that penetrates the strain gauge is formed along the cylinder axis direction of the mold, and from the through part to support the through part A plurality of support extending portions extending outwardly until inscribed in the inner surface of the mold, and configured such that the central axis of the mold is located in the through hole of the through portion. It is characterized by.

  According to the strain gauge installation jig having the above-described configuration, in a state where the strain gauge is used in the mold, the plurality of support extending parts are in contact with the inner surface of the mold and support the penetrating part from the outside. In addition, the through portion is arranged in the mold so that the central axis of the mold is located in the through hole of the through portion. Therefore, the strain gauge can be easily installed along the central axis of the mold by passing through the through hole and arranging the strain gauge in the mold.

  As described above, the strain gauge installation jig according to the present invention has an effect that the strain gauge can be easily installed in the cylindrical formwork. Further, since the strain gauge can be installed along the center axis of the mold, there is an effect that the strain measurement can be performed with sufficient accuracy by the installed strain gauge.

The figure showing the mode after installing a strain gauge in a formwork using the jig for strain gauge installation. The schematic diagram which represented the jig | tool for installation of a strain gauge typically. The figure showing the formwork and strain gauge which were used in the comparative example. The graph which shows the result of distortion measurement of a cement hardening body.

  Hereinafter, embodiments of a strain gauge installation jig according to the present invention will be described with reference to the drawings.

FIG. 1A shows a state after the mold 10 is installed so that the cylinder axis direction is the vertical direction, the jig 1 is installed in the mold 10, and the strain gauge 8 is further arranged. It is the longitudinal cross-sectional view cut | disconnected along the cylinder axial direction so that the central axis A of a frame may be passed. Moreover, FIG.1 (b) is the perspective view which looked at said state from the downward side.
FIG. 2 is a longitudinal sectional view and a bottom view of the two jigs 1 installed in the mold 10.

  The strain gauge installation jig of the present embodiment is a strain gauge installation jig 1 used for installing a long strain gauge 8 in a cylindrical mold 10, and is provided in the mold 10. In the state to be used, the cylindrical penetrating portion 2 formed with a through hole 2a penetrating the strain gauge 1 along the cylinder axis direction of the mold 10 and the penetrating portion to support the penetrating portion 2 2 and a plurality of support extending portions 3 extending outward from the inner surface of the mold 10 so that the center axis A of the mold 10 is located in the through hole 2a of the through portion 2. It is comprised so that it may do.

As shown in FIG. 1, the strain gauge installation jig 1 is usually used in a hollow cylindrical mold frame arranged so that the cylinder axis direction is the vertical direction.
Further, the jig 1 is used to install the strain gauge 8 in the mold 10, and as shown in FIG. 1, for example, two are arranged apart from each other in the cylinder axis direction in the mold. Is done. After the strain gauge 8 is installed, for example, a cement fluid before hardening is poured into the mold 10 to produce a hardened cement body.

As shown in FIG. 1, when the jig 1 is used in the mold 10, the through-hole 2 a having a through-hole 2 a that penetrates the strain gauge 8 along the cylinder axis direction of the mold 10 is formed. It has. The through portion 2 is arranged in the mold 10 so that the central axis A of the mold 10 is located in the through hole 2a.
Further, as shown in FIG. 1, the jig 1 includes a plurality of support extending portions 3 that extend outward from the penetrating portion 2 in the radial direction of the mold and in contact with the inner surface of the mold. The supporting extension part 3 supports the penetrating part 2 from the outside while working together in the mold 10.

  Specifically, as shown in FIG. 2, the jig 1 includes the penetrating portion 2 and two supporting extending portions extending from the penetrating portion 2 in the radial direction of the mold 10 and in opposite directions. 3 is provided.

As shown in FIG. 1, the jig 1 is configured to be fixed at a predetermined position of the mold 10 by abutting each end of the supporting extension 3 with the inner surface of the mold 10. Has been. That is, the jig 1 has a length from the end of one support extension 3 to the end of the other support extension 3 that is the same as the inner diameter of the mold 10. And it is comprised so that there may be no clearance gap between the inner surface of the formwork 10, and the edge part of each supporting extension part 3. FIG.
With such a configuration, the jig 1 is restricted from moving at a predetermined position in the mold 10 by the frictional force between the inner wall of the mold 10 and the outer end of each supporting extension 3. .

  The supporting extension 3 is formed of an elastic material and is arranged in the mold 10 while being compressed in the extending direction, thereby pressing the inner surface of the mold 10 by elasticity. You may be comprised so that the penetration part 2 may be supported from the circumference | surroundings of the penetration part 2. FIG.

Furthermore, when the jig 1 is arranged in the mold 10, the center axis A of the mold 10 is positioned in the through hole 2 a of the through portion 2 as shown in FIG. 1. ing. Specifically, the two support extending portions 3 are formed in the same shape, and are attached to the penetrating portion 2 so that the directions are opposite in the radial direction of the mold. Further, the two support extending portions 3 support the penetrating portion 2 from opposite directions, so that the two supporting extending portions 3 have the center axis A of the mold 10 that is the through hole 2 a of the penetrating portion 2. The penetrating part 2 is arranged in the mold 10 so as to be located inside.
Therefore, the strain gauge installation jig 1 arranged in the mold 10 can install the strain gauge 8 along the central axis A of the mold 10.

  The penetrating portion 2 is formed in a cylindrical shape, and a long strain gauge 8 is provided in the penetrating portion 2 in a state where the jig 1 is used in the mold 10. A through hole 2a penetrating in the direction is formed. The through hole 2a is not particularly limited in size and shape as long as it is formed so that the strain gauge 8 can penetrate therethrough.

  The supporting extension 3 preferably extends radially from the penetrating part 2 so as to form the same angle with each other in that the penetrating part 2 can be supported from the outer side with a more uniform force. Specifically, when the supporting extension 3 is provided in the jig 1, the four supporting extensions 3 extend radially from the penetrating part 2 at an angular interval of 90 degrees. In the case where the jig 1 is provided with three supporting extension portions 3, the three supporting extension portions 3 may extend radially from the penetration portion 2 at an angular interval of 120 degrees. preferable. Further, when the jig 1 is provided with two supporting extension portions 3, as shown in FIGS. 1 and 2, the two supporting extension portions 3 are arranged in opposite directions from the penetrating portion 2. Preferably it extends.

  The material constituting the support extension 3 is preferably a material having an appropriate rigidity, for example, it is difficult to change the quality in a hardened cement body and, for example, a fluid before the cement is hardened is placed. A resin such as an acrylic resin or a vinyl chloride resin is more preferable in that it is difficult to break.

  As shown in FIGS. 1 and 2, the supporting extension 3 extends from the penetrating part 2 to the outer side and extends from the outer side to support the penetrating part 2 and the extending part main body 3a. And an inscribed member 3b formed so as to be in contact with the inner surface of the mold 10.

The extension part main body 3a is formed in a rod shape with such a strength that it will not be damaged by an impact when a cement fluid before hardening is placed in the mold 10. In addition, the occupied volume in the mold 10 is made as small as possible so as not to prevent the force generated by the distortion of the hardened cement body from being transmitted to the strain gauge 8.
Specifically, the extension body 3a is formed in a rod shape having a thickness of 3 to 5 mm when the mold 10 is formed in a cylindrical shape of φ100 mm (opening inner diameter) × 200 mm (cylinder axis length). It is preferable.

  The inscribed member 3b is formed so as to be in contact with the inner surface of the mold 10, and when the mold 10 is cylindrical, as shown in FIG. It is formed to draw the same arc as the inner surface of.

  As shown in FIG. 1, a plurality of jigs 1 are preferably arranged in a mold 10 for use. That is, it is preferable to use a jig set configured such that a plurality of jigs 1 are arranged along the cylinder axis direction of the mold 10 in the mold 10. By using such a jig set, at least two points separated from each other in the longitudinal direction of the strain gauge 8 pass through the central axis A of the mold 10, and the strain gauge 8 can be more securely connected to the center of the mold 10. It can be arranged along the axis A.

  Specifically, as shown in FIGS. 1 and 2, the jig set preferably includes two upper jigs and lower jigs as the jig 1. By providing the two jigs 1, the strain gauges 8 can be more reliably arranged along the center axis A of the mold 10, and three jigs 1 are used for measuring strain of a cemented body or the like. The occupied volume of the jig 1 in the cured body is smaller than that in the above case, and there is an advantage that the adverse effect on the strain measurement by the jig 1 can be suppressed.

  The jig set is mounted on the lower side of the penetrating portion 2 of the lowermost jig 1 with the strain gauge 8 installed in the mold 10 and serves as a base 5 that supports the lower end of the strain gauge 8. It is preferable to provide. By providing the pedestal 5, the strain gauge 8 can be installed in the mold 10 in a state where the strain gauge 8 is separated from the bottom plate 11. Therefore, the strain gauge 8 can be reliably installed in the inner space of the mold 10, and the strain gauge 8 can be reliably embedded in the hardened cement body or the like. When such a pedestal 5 is used, the strain gauge is installed in the mold by penetrating at least one through hole of the plurality of jigs, for example, the through hole of the upper jig.

  The material constituting the strain gauge installation jig 1 is not particularly limited, but a resin such as an acrylic resin or a vinyl chloride resin is preferable for the same reason as the material in the above-described supporting extension portion 3.

  Next, the mold 10 capable of accommodating the strain gauge installation jig 1 in an internal space will be described.

  As shown in FIG. 1, the mold 10 is formed in a cylindrical shape, for example. A disk-shaped bottom plate 11 that closes the lower opening of the mold 10 is attached to the lower side of the mold 10.

  As shown in FIG. 1, the mold 10 is usually installed so that the cylinder axis extends in the vertical direction when producing a hardened cement body or the like. Further, the strain gauge installation jig 1 is inserted into the hollow interior from above, and fluid cement and the like before curing are poured. The mold 10 does not necessarily have to be arranged so that the cylinder axis extends in the vertical direction, and may be arranged so that the cylinder axis extends in the horizontal direction.

  The mold 10 in which the hardened cement body or the like is manufactured in the internal space has a more accurate shrinkage measurement of the hardened cement body or the like because the hardened cement body or the like manufactured in the mold 10 contracts more evenly. In that respect, it is preferably formed in a cylindrical shape as shown in FIG.

The center axis A of the mold 10 is an axis that connects the centers of the circles in the circles drawn by the respective openings at both ends of the mold 10 if the shape of the mold 10 is cylindrical as shown in FIG. It is.
Further, if the shape of the mold 10 is a shape other than a cylindrical shape such as a quadrangular prism, the center axis A of the mold 10 has the same length in the cylinder axis direction and is the maximum inscribed in the mold 10. In the cylindrical body, the axis is defined in the same manner as the cylindrical formwork.

Since the hardened cement body or the like for measuring the strain is manufactured in the mold 10, the outer surface shape of the hardened cement body or the like corresponds to the inner surface shape of the mold frame 10. That is, as shown in FIG. 1, if the mold 10 is formed in a hollow cylindrical shape, the produced cemented body or the like has a solid cylindrical shape. Therefore, the central axis A of the mold 10 coincides with the central axis of the cemented hardened body or the like produced in the mold.
When the cement hardened body shrinks, the cement hardened body is distorted along with the shrinkage. The magnitude of the force generated by the distortion varies depending on each part of the cured body. For example, in the horizontal section of the cured body produced in the mold shown in FIG. Is the largest in the central axis of the, and becomes smaller toward the outer side. Also, the force generated by the distortion works more uniformly on the central axis, but can work more unevenly on the outer side. For this reason, it is necessary to measure the strain at the central axis of the cured body in order to accurately measure the strain of the cylindrical cement cured body.

  The material of the mold 10 is not particularly limited, and examples of the material of the mold 10 include metals and resins.

Although the size of the mold 10 is not particularly limited, the length in the cylinder axis direction is preferably 150 to 400 mm, and the inner diameter is 40 in that it is easy to measure strain of a cemented body or the like. It is preferable that it is -150mm. Specifically, for example, a hollow cylindrical shape having a length of 200 mm in the cylinder axis direction and an inner diameter of 100 mm can be used as the mold 10.
The thickness of the mold 10 is not particularly limited, but is usually 1 to 10 mm.

Next, a method of using the strain gauge installation jig 1 will be described.
The strain gauge installation jig 1 can be used to install the strain gauge 8 in the mold 10. Thereafter, for example, a hardened cement body is prepared in the mold 10 and the strain gauge 8 is embedded in the hardened cement body, and the strain of the hardened cement body can be measured by the embedded gauge.
Specifically, the jig 1 can be used as follows, for example.

First, the cylindrical mold 10 is arranged such that the cylinder axis direction of the mold 10 is the vertical direction. In addition, the bottom plate 11 is attached to the lower side of the mold 10 so as to close the lower opening of the mold 10.
On the other hand, the two jigs 1 (upper jig and lower jig) formed of resin are prepared. As shown in FIGS. 1 and 2, the pedestal 5 described above is attached to the penetrating portion 2 of the lower jig disposed on the lower side of the mold 10.
Next, the lower jig is put into the mold 10 until the pedestal 5 attached to the lower jig becomes the lower side and the pedestal 5 comes into contact with the bottom plate 11. Further, the upper jig is placed in the mold 10 so that the distance between the upper jig and the lower jig is shorter than the length of the strain gauge 8. Each jig 1 placed in the mold 10 is restricted from moving in the mold 10 by the frictional force with the inner wall of the mold 10. Further, the penetrating portion 2 is arranged so that the central axis A of the mold 10 is positioned in the through holes 2 a of the two jigs 1.
Then, the long strain gauge 8 is passed through the through hole 2 a of the penetrating portion 2 of the upper jig disposed in the mold 10, and the strain gauge 8 is installed in the mold 10. Thereby, the strain gauge 8 can be disposed in the mold 10 along the central axis A of the cylindrical mold 10. The strain gauge 8 is provided with a lead wire 9 for transmitting a change in electric resistance value due to strain, and the lead wire 9 can be connected to a detector outside the mold 10.

Thereafter, the fluid before the hardened cement body is cured can be poured into the mold 10 from above and placed.
Furthermore, the hardened cement hardening body can be obtained by curing for a predetermined period.
Subsequently, the strain of the hardened cement body is measured by leaving the hardened cement body under a predetermined condition and detecting the strain of the strain gauge 8 embedded in the hardened body in the hardened body of a predetermined age. Can do. Note that the measurement of strain may be performed after the mold 10 is removed, or may be performed in a state where there is a hardened cement body in the mold 10.

  As the strain gauge 8, a conventionally known general one can be used, and specifically, for example, one formed in a plate shape, a rod shape, a film shape or the like can be mentioned. As shown in FIG. 1, the strain gauge 8 is usually provided with a lead wire 9 for transmitting a change in electric resistance value due to strain to an external detector.

  As cement which comprises the said cement hardening body, the cement prescribed | regulated by JISR5210-5213 can be used, for example. Specifically, for example, normal Portland cement, early-strength Portland cement, Portland cement such as low heat Portland cement (JIS R5210), blast furnace cement containing blast furnace slag (JIS R5211), silica cement containing silka (JIS R5212), fly Fly ash cement containing ash (JIS R5213) or the like can be used.

  The cement hardened body is not particularly limited as long as the cement is hardened by a hydration reaction, and for example, a cement containing at least cement and an aggregate can be used. Specifically, for example, hardened mortar containing cement and fine aggregate, hardened concrete containing cement, fine aggregate, and coarse aggregate can be used.

  The cement hardened body is prepared in the mold 10 after being mixed with at least the cement and water, poured into the mold 10 and cured by curing for a predetermined period of time.

  The jig 1 is usually discarded together with the hardened cement body and the like without being used again after performing a strain test.

The present invention is not limited to the above illustrated strain gauge installation jig.
Moreover, the various aspects used in the general jig | tool for a strain gauge installation are employable in the range which does not impair the effect of this invention.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

(Example)
First, a tin summit can (manufactured by Sumisho Cement Co., Ltd.) having an inner diameter φ100 mm × height 200 mm was prepared. The summit can is configured such that a bottom plate that closes the opening is attached to one opening of a cylindrical mold, and the bottom plate is disposed on the lower side. Moreover, the strain gauge installation jig shown in FIG. 2 to be arranged on the upper side and the lower side inside the summit can was prepared. A columnar pedestal having a diameter of 10 mm and a height of 10 mm was attached to the lower side of the lower jig disposed on the lower side.
The size of the through hole in each jig was 13.5 mm × 5.5 mm so that a long plate-shaped strain gauge (cross section 13 mm × 5 mm, length 180 mm) could penetrate.
Next, jigs were respectively arranged on the upper side and the lower side in the mold. The distance between the two jigs in the vertical direction was set to be shorter than the length in the extending direction of a long strain gauge to be installed in the mold later. Then, a strain gauge having a lead wire attached on the upper side was placed in the mold, and the strain gauge was installed in the mold so as to penetrate the through hole of the upper jig.
On the other hand, in order to produce hardened concrete as a hardened cement body, 14.8 parts by weight of ordinary Portland cement, 7.4 parts by weight of water, 34.4 parts by weight of fine aggregate, and 43.4 parts by weight of coarse aggregate Were mixed according to a conventional method.
Subsequently, the mixture mixed as described above was placed in a mold. After placing, the mixture was left in a wet state at 18 to 22 ° C. for 24 hours while the mixture was put in the mold. Thereafter, the mold was removed, and the cured product was cured in water at 18 to 22 ° C. until the age of the material reached 7 days.
And the specimen (hardened concrete) on the age of 7 days is left to stand under the conditions of 18 to 22 ° C. and humidity of 55 to 65%, and the distortion of the hardened concrete in 28 days by the strain gauge embedded in the hardened concrete. Was measured.

(Comparative example)
The strain of the hardened concrete was measured in the same manner as in the example except that the strain gauge was not installed in the mold and was not used as described below.
That is, as shown in FIG. 3, the strain gauge was placed in the mold so that the lead wire attached to the strain gauge was placed above the strain gauge. Further, a bar Z having a length exceeding the inner diameter was disposed on the summit can in the horizontal direction, and a lead wire was bonded to the bar. On the other hand, a hole was made in the lower end of the strain gauge and the center of the circle of the bottom plate, a thread was passed through both holes, and the yarn was fixed to the bottom plate while pulling the thread downward. Thus, the strain gauge was installed in the mold so as to be along the central axis of the cylindrical mold.

  FIG. 4 shows the measurement results of strain in the examples and comparative examples. As shown in FIG. 4, in the example and the comparative example, equivalent strain measurement results were obtained. That is, in the example, the distortion could be measured with high accuracy.

1: Strain gauge installation jig 2: Through part, 2a: Through hole 3: Supporting extension part, 3a: Extension part main body, 3b: Inscribed member 5: Base 8: Strain gauge 9: Lead wire 10: Formwork, 11: Bottom plate A: Center axis

Claims (1)

A strain gauge installation jig used to install a long strain gauge in a tubular mold,
In a state of use in the mold, a cylindrical through part in which a through hole that penetrates the strain gauge is formed along the cylinder axis direction of the mold, and from the through part to support the through part A plurality of supporting extension portions extending outwardly until inscribed in the inner surface of the mold, and the strain is configured such that the central axis of the mold is located in the through hole of the through portion Gauge installation jig.

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