JPS58111702A - Strain detector - Google Patents

Abstract

PURPOSE:To facilitate attachment and to make it possible to perform accurate measurement, by holding a thin strain generating plate, to which strain gages are attached, by two reinforcing plates having through holes, fixing tham by fixing members having attaching parts to a material to be measured, and applying a hard filler on the outer surface and curring it. CONSTITUTION:The reinforcing plate 2 has the through holes 2a and 2b and reinforcing ribs 2c on one side. The strain gages SG are bonded to the upper and bottom sides of the center of a narrow strain generating part 1a of the strain generating part 1. The surfaces of two reinforcing plates 2 having no reinforcing ribs 2c are contacted with both surfaces of the strain generating plate 1. The cylinder part of a flanged cylinder body of the fixing members 3 is inserted into the through hole 2b of the reinforcing plate 2 and a through hole 1b of the strain generating plate 1. A ring body 3b is coupled with the protruded cylinder part, and thereafter they are fixed by caulking so as to form a unitary body. The filler such as epoxy is applied to the same height as the reinforcing ribs 2c on the outer surface of the reinforcing plate 2 and cured and a molded body 4 is formed. The strain detector can be readily bolted to the material to be measured through a round hole 3c of the fixing member 3. Since the molded body 4 is provided, buckling does not occur, and the accurate amount of compression strain is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hustle detector that provides an electrical output signal.

For example, when a compressive strain is detected by this type of strain detector and measured by a strain measuring device, a buckling phenomenon may occur in the strain-generating plate, particularly in the strain-generating portion, and accurate strain measurement may not be possible.゛Therefore, in some conventional strain detectors, the strain-generating part (sensing part) of the strain-generating plate is formed into a hollow thick-walled cylinder or a square cross-section to increase the cross-sectional shape. Some are designed to prevent buckling.

However, in such conventional strain detectors, the cross section of the strain-generating part is large, so if there are irregularities on the mounting surface of the object to be measured (for example, a rough surface such as the so-called black surface of a casting), strain detection becomes difficult. When the strain detector is installed, bending force acts on the strain detector, and the output due to the bending force is considerably reduced, making it impossible to accurately measure the tensile strain or compressive strain of the object to be measured. Not only was this not possible, but in extreme cases, the measurement range could be significantly exceeded during the installation stage, making measurements impossible.

In order to avoid this situation, in the past, the mounting surface of the strain detector on the object to be measured was finished to be a smooth flat surface, and the bolt holes or screw holes were precisely finished using reamers or precision taps for mounting. This kind of work requires special jigs and tools, and takes a lot of time.
This was a contributing factor to the increase in jig and tool costs and labor costs.

In addition, the conventional strain detectors described above have a large cross section of the sensing part to prevent buckling, which increases the rigidity of the object to be measured. It has been difficult to accurately detect distortion because the distortion is supported by the rigidity of the story itself. Furthermore, in manufacturing the above-mentioned conventional strain detector,
Since the strain-generating portions have to be formed by cutting round rods or square pieces, processing costs have inevitably increased.

The present invention was developed in view of the above circumstances, and is easy to manufacture and attach to an object to be measured, has low rigidity against compression and tension, does not buckle under compression, and has almost no effect on bending. The purpose of the present invention is to provide a strain detector that does not suffer from any damage.

An object of the present invention is to provide a thin strain-generating plate having a strain-generating part formed narrowly in the center and having a strain gauge attached thereto; Two thin plate-shaped reinforcing plates are formed with through holes and reinforcing ribs are formed on both sides to prevent buckling, and are stacked so as to sandwich the strain plate from both sides. a fixing member that fixes the plate together at both ends thereof and has a mounting part for the object to be measured in the fixing part; at least the outer plate surface of the two reinforcing plates fixed by the fixing member and the fixing member. This is achieved by constructing a molded body for preventing buckling, which is formed by filling and solidifying a hard filler in the periphery of the mold.

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

1 to 5 each show the configuration of an embodiment of the present invention, FIG. 1 is an exploded perspective view, FIG. 2 is a plan view,
3 is a cross-sectional view taken along the line A--A in FIG. 2, FIG. 4 is a front view, and FIG. 5 is a cross-sectional view taken along the line B--B in FIG.

In FIGS. 1 to 5, reference numeral 1 denotes a strain plate made of a thin plate material. The strain plate 1 is provided with a strain part 1a formed narrowly in the center, and the strain plate 1 is provided with a strain part 1a formed narrowly in the center. There are circular through holes 1b near both ends in the load direction).

1b, and two strain gauges are attached to each of the front and back sides of the strain-generating portion 1a by means of adhesive or the like.

Reference numeral 2 denotes a reinforcing plate, and a rectangular through hole 2a larger than the attachment area of the strain gauge SG attached to the strain-generating plate 1 is bored in the center of the reinforcing plate 2. Near both ends in the longitudinal direction, circular holes 2b are bored at the same distance and with the same diameter as the two through holes 1b provided in the strain plate 1. A reinforcing lip 2c for preventing buckling is provided on both ends of the rim (in the direction of bending), which is bent at 90 degrees to the same side. The reinforcing plate 2 is made of a thin plate material, and the through holes 2a and 2b are punched out using a press machine, for example, and the reinforcing lips 2c are bent and formed.

3 is a fixing member, which includes a cylindrical body 3a with a flange having a circular hole 3C in the center, and a ring having an inner diameter that fits into the cylindrical portion of the cylindrical body 3a with a flange and the same outer diameter as the flange. The body 3b serves to fix the strain plate 1 and the reinforcing plate 2 together as described below. In FIGS. 3 and 5, 4 is a molded body for buckling prevention made by hardening a hard filler such as epoxy resin or synthetic rubber, and the elastic modulus is, for example, the strain plate 1.
Those with a value of 1/10 or less are selected.

The strain detector 5 having such a configuration is assembled as follows.

First, as can be inferred from what is shown in FIG. 2, the surfaces of the two reinforcing plates 2 opposite to the surfaces with the reinforcing ribs 2C are brought into contact with the strain-generating plate 1, and the strain-generating plate 1 is The cylindrical portion of the flanged cylindrical body 3, which is one of the fixing members 3, is fitted into the through hole 2b of the reinforcing plate 2 and the through hole 1b of the strain plate 1,
The reinforcing plate 2 on the opposite side is made to protrude outward, and then the ring body 3b
6- After fitting into the protruding cylindrical portion, the cylindrical portion is caulked, and the strain plate 1 and the two reinforcing plates 2 are fixed together near both ends thereof to be integrated.

Filler material such as the epoxy resin is placed on the surface of the two reinforcing plates 2 of the integrated strain detector 5 on which the reinforcing ribs 2C are provided, at a height that is approximately the same as the height of the reinforcing ribs 2c. The mold body 4 is filled by filling it to the extent that it is solid and solidifying it.
form. At this time, the filler is the strain-generating portion 1 of the strain-generating plate 1.
a, it also flows into the surrounding areas of the strain gauge SG and the fixing member 30, so that these are integrated via the molded body 5, so to speak. This state is shown in FIGS. 2 to 5.

To explain the operation of the present invention configured in this way, first, a hole or screw hole for a bolt (not shown) for attaching the strain detector 5 to the object to be measured is formed, and the bolt is attached to the fixing member. The strain detector 5 is attached to the object to be measured by inserting it into the oval hole 3c provided in the object to be measured and screwing it into, for example, the screw hole provided in the object to be measured.

If a compressive load is applied to this object to be measured,
Mounting bolt (not shown), fixing member 3 of strain detector 5
The strain plate 1, two reinforcing plates 2 and the molded body 4 are
These are compressed in the longitudinal direction (load direction)
It contracts in the width direction (direction perpendicular to the load direction). As a result, the two strain gauges SG attached to the front and back surfaces of the strain-generating portion 1a of the strain-generating plate 1 also deform in accordance with the contraction or expansion of the strain-generating portion 1a. Generally, the strain gauges SG are attached to the front and back surfaces of the strain-generating portion 1a in a direction perpendicular to the load direction stop, and these four strain gauges constitute a Wheatstone bridge. Therefore,
The output end of this bridge sends out an output signal corresponding to the strain (compressive strain in this case) in the strain-generating section 1a, so the amount of strain can be measured using a strain measuring device (not shown). . When this compressive strain is detected by the strain detector 5 according to the above embodiment,
Since the structure is such that the reinforcing plate 2 also receives the compressive force applied to the strain detector 5, buckling can be prevented by the reinforcing ribs 2c of the reinforcing plate 2. Moreover, since the molded body 4 forms a large compression and tension cross section of the strain detector 5, this molded body 4 also effectively acts against buckling. Therefore, even when a large compressive strain occurs, there is no buckling, and the amount of compressive strain can be accurately detected.

On the other hand, when detecting tensile strain, 1- can be measured in the same manner (although buckling is irrelevant).

Furthermore, the strain-generating portion 1a is formed narrowly, and the reinforcing plate 2 is made of a thin plate material, and a through-hole 2a is formed in the center (although this through-hole 2a can separate the reinforcing plate 2 and the strain-generating plate 1). The molded body 4 has a much smaller elastic modulus than the strain-generating plate 1 (for example, 1/10 (Below) Since the strain detector 5 is made of a filling material that is different from the material, the rigidity of the strain detector 5 as a whole is small. Therefore, it is possible to detect the compressive strain of objects to be measured with low rigidity such as thin plates and plastics. − is.

Furthermore, when installing the strain detector 5 on the object to be measured, if the mounting surface is rough to some extent, or if the two bolt mounting holes provided in the object to be measured are not properly drilled in parallel. When bending is applied to the strain detector 5, the strain plate 1 is also bent, but the strain gauge SG is attached to the strain part 1a at the center of the strain plate 1, and the strain plate 1 is The two reinforcing plates 2, 2 are stacked in a sandwich-like manner, and the molded body 4 is also formed symmetrically on both sides (bottom side in the figure). Even if bending is applied, the bending stress is close to zero, so almost no bending output is sent out from the strain gauge SG. The detector can be mounted directly, making installation extremely easy.

Moreover, since the strain gauge SG is covered by the molded body 4, it is isolated from the outside air and can prevent insulation from deteriorating due to moisture absorption.

10-1 Furthermore, the strain plate I and the reinforcing plate 2 are made by punching a thin plate material,
Since it is only necessary to bend and form, it can be easily processed using a press machine and manufacturing costs can be reduced.

Note that the present invention is not limited to the above-described embodiments, but can be implemented with various modifications.

For example, the shape of the reinforcing ribs of the reinforcing plate, the fixing member, etc. can be changed as appropriate.

Further, the strain detector 5 itself can be used by being housed in a case 6 made of plastic, for example, as shown in FIGS. 6 and 7. In this case, the case 6 is sized to accommodate the strain detector 5 with plenty of room, and is provided with a circular through hole 6a through which a part of the fixing member 3 can protrude, and one end of the case 6 is provided with a circular through hole 6a through which a part of the fixing member 3 can protrude. Derive the output,
A cable 7 is connected to transmit the strain to the strain measuring instrument.

As detailed above, according to the present invention, it is easy to manufacture and attach to the object to be measured, and the rigidity against compression and tension is small, and buckling does not occur under compression, so compressive strain can be detected. It is possible to provide a strain detector that has a large range and can suppress the influence on bending to a negligible extent.

[Brief explanation of the drawing]

Figures 1 to 5 all show the configuration of an embodiment of the present invention, where Figure 1 is an exploded perspective view, Figure 2 is a plan view, and Figure 3 is taken along line A-A in Figure 2. 4 is a front view, FIG. 5 is a sectional view taken along line B-B in FIG. 2, and FIGS. 6 and 7 show the strain detector according to the present invention housed in a case. FIG.

Claims (1)

[Claims] +11 - A thin plate-shaped strain-generating plate having a strain-generating part formed narrowly in the center and having a strain gauge attached thereto, and a through hole larger than at least the area to which the strain gauge is attached is formed in each center part, and both sides thereof. two thin reinforcing plates stacked on top of each other so as to sandwich the strain plate from both sides, and reinforcing ribs to prevent buckling are formed on the parts, and these two reinforcing plates and the strain plate are attached to both ends thereof. a fixing member that is fixed together and has an attachment part to the object to be measured in the fixed part, and a hard filler on at least the outer plate surface of the two reinforcing plates fixed by this fixing member and the periphery of the fixing member. A strain detector comprising: a mold body for preventing buckling formed by filling and solidifying a mold body for preventing buckling.